Guide Specification for High Performance Concrete for Bridges

Michael A. Caldarone, Peter C. Taylor, Rachel J. Detwiler, Shrinivas B. Bhide Guide Specification for High-Performance Concrete for Bridges

FIRST EDITION

by Michael A. Caldarone, Peter C. Taylor, Rachel J. Detwiler, and Shrinivas B. Bhidé

Portland Cement Association 5420 Old Orchard Road Skokie, Illinois 60077-1083 847.966.6200 Fax 847.966.9781 www.cement.org

An organization of cement companies to improve and extend the uses of portland cement and concrete through market development, engineering, research, education, and public affairs work. Guide Specification for High-Performance Concrete for Bridges

KEYWORDS: AASHTO, abrasion resistance, admixtures, aggregates, air-entrained concrete, air void analyzer, alkali-carbonate reactivity, alkali-silica reactivity, ASR, ASTM, bridge, cement, cementitious materials, chemical admixtures, chloride ion penetration, cold weather, compressive strength, consistency, corrosion inhibitors, crack control, cracking, creep, curing, D-cracking, deck, durability, finishing, flowing concrete, footing, freeze/thaw durability, fly ash, girder, guide specification, high-performance concrete, hot weather, mass concrete, mixture proportioning, modulus of elasticity, pier, placing, portland cement concrete, performance, properties, quality assurance, quality control, ready mixed concrete, scaling resistance, SCC, self consolidating concrete, shrinkage, silica fume, slag cement, spacing factor, standards, structural concrete, sulfate resistance, supplementary cementitious materials, temperature control, tests, trial batches, volume changes, and water-cementitious materials ratio, w/cm.

ABSTRACT: This guide specification is intended to serve as a guide for developing specifications for all high performance concretes supplied for highway bridges, whether produced by a ready mix supplier, a general contractor, or in a permanent plant of a precast concrete manufacturer. For the purposes of this specification, high performance concrete (HPC) is considered as concrete engineered to meet specific needs of a project; including: mechanical, durability, or constructability properties. The document provides mandatory language that the specifier can cut and paste into project specifications. It also includes guidance on what characteristics should be specified in a given case, and what performance limit is needed to ensure satisfactory performance for a given element or environment.

REFERENCE: Michael A. Caldarone, Peter C. Taylor, Rachel J. Detwiler, and Shrinivas B. Bhidé; Guide Specification for High- Performance Concrete for Bridges, EB233, 1st edition, Portland Cement Association, Skokie, Illinois, USA, 2005, 64 pages.

Cover photo: Confederation Bridge, New Brunswick and Prince Edward Island, Canada, © 2005 Boily. © Portland Cement Association 2005 All rights reserved. PCA grants permission to include any or all parts of this document in specific project specifications.

ISBN 0-89312-245-9

WARNING: Contact with wet (unhardened) concrete, mortar, cement, or cement mixtures can cause SKIN IRRITATION, SEVERE CHEMICAL BURNS (THIRDDEGREE), or SERIOUS EYE DAMAGE. Frequent exposure may be associated with irri- tant and/or allergic contact dermatitis. Wear waterproof gloves, a long-sleeved shirt, full-length trousers, and proper eye protection when working with these materials. If you have to stand in wet concrete, use waterproof boots that are high enough to keep concrete from flowing into them. Wash wet concrete, mortar, cement, or cement mixtures from your skin immediately. Flush eyes with clean water immediately after contact. Indirect contact through clothing can be as serious as direct contact, so promptly rinse out wet concrete, mortar, cement, or cement mixtures from clothing. Seek immediate medical attention if you have persistent or severe discomfort.

Portland Cement Association ("PCA") is a not-for-profit organization and provides this publication solely for the continuing education of qualified professionals. THIS PUBLICATION SHOULD ONLY BE USED BY QUALIFIED PROFESSIONALS who possess all required license(s), who are competent to evaluate the significance and limitations of the information provided herein, and who accept total responsibility for the application of this information. OTHER READERS SHOULD OBTAIN ASSISTANCE FROM A QUALIFIED PROFESSIONAL BEFORE PROCEEDING.

PCA AND ITS MEMBERS MAKE NO EXPRESS OR IMPLIED WARRANTY WITH RESPECT TO THIS PUBLICATION OR ANY INFORMATION CONTAINED HEREIN. IN PARTICULAR, NO WARRANTY IS MADE OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. PCA AND ITS MEMBERS DISCLAIM ANY PRODUCT LIABILITY (INCLUDING WITHOUT LIMITATION ANY STRICT LIABILITY IN TORT) IN CONNECTION WITH THIS PUBLICATION OR ANY INFORMATION CONTAINED HEREIN.

Research Index No. 02-05 EB233 R&D Serial No. 2755 ii Table of Contents

Title Page ...... i Keywords, Abstract, and Reference ...... ii About the Authors ...... vi Acknowledgments ...... vi Introduction ...... 1 1.0 Scope...... 2 2.0 References ...... 2 2.1 American Association of State Highway and Transportation Officials (AASHTO) ...... 2 2.2 American Society for Testing and Materials International (ASTM International)...... 3 2.3 U.S. Department of Transportation, Federal Highway Administration ...... 4 2.4 American Concrete Institute (ACI) ...... 4 2.5 Portland Cement Association (PCA) ...... 5 2.6 Precast/Prestressed Concrete Institute (PCI)...... 5 2.7 National Ready Mixed Concrete Association (NRMCA) ...... 5 3.0 Definitions ...... 5 4.0 Performance Requirements...... 7 4.1 Abrasion Resistance ...... 7 4.2 Chloride Ion Penetration ...... 7 4.3 Compressive Strength ...... 7 4.4 Creep ...... 7 4.5 Modulus of Elasticity ...... 7 4.6 Freeze/Thaw Durability...... 7 4.7 Scaling Resistance ...... 7 4.8 Shrinkage ...... 7 4.9 Sulfate Resistance ...... 7 4.10 Consistency ...... 8 4.11 Alkali-Silica Reactivity...... 8 5.0 Materials ...... 8 5.1 Cementitious Materials ...... 8 5.2 Aggregates ...... 8 5.2.1 Grading and Impurities...... 8 5.2.2 Durability ...... 8 5.2.2.1 Alkali-Silica Reactivity ...... 9 5.2.2.2 Alkali-Carbonate Reactivity ...... 9 5.2.2.3 D-Cracking ...... 9 5.3 Water ...... 10

iii 5.4 Chemical Admixtures ...... 10 6.0 Submission and Design Requirements ...... 10 6.1 Concrete Mixture Proportioning...... 10 6.2 Concrete Production Facility Certification ...... 10 6.3 Concrete Materials...... 10 6.4 Temperature Control Methods ...... 10 6.5 Crack Control Methods ...... 10 6.6 Curing ...... 11 6.7 Quality Control Plan...... 11 7.0 Quality Management ...... 11 7.1 Quality Assurance ...... 11 7.2 Quality Control ...... 12 8.0 Production of Concrete ...... 12 8.1 General...... 12 8.2 Equipment ...... 13 8.2.1 Within-Batch Uniformity...... 13 8.2.2 Non-Agitating Equipment...... 13 8.2.3 Agitating Equipment ...... 13 8.3 Measurement of Materials ...... 13 8.4 Mixing ...... 13 8.5 Temperature Control...... 14 8.5.1 Cold Weather...... 14 8.5.2 Hot Weather ...... 14 8.5.3 Control of Temperature Differences ...... 14 8.6 Trial Batches and Mockups ...... 15 8.7 Site Addition of Materials ...... 15 8.8 Delivery Tickets ...... 15 C1.0 Scope ...... 17 C2.0 References ...... 17 C3.0 Definitions ...... 17 C4.0 Performance Requirements ...... 17 C4.1 Abrasion Resistance...... 21 C4.2 Chloride Ion Penetration ...... 21 C4.3 Compressive Strength...... 22 C4.4 Creep ...... 23 C4.5 Modulus of Elasticity ...... 24 C4.6 Freeze/Thaw Durability ...... 25 C4.7 Scaling Resistance ...... 27 C4.8 Shrinkage ...... 27 C4.8.1 Plastic Shrinkage ...... 28

iv C4.8.2 Autogenous Shrinkage...... 29 C4.8.3 Drying Shrinkage...... 30 C4.9 Sulfate Resistance ...... 30 C4.10 Consistency ...... 32 C4.11 Alkali-Silica Reactivity...... 35 C5.0 Materials ...... 36 C5.1 Cementitious Materials...... 36 C5.2 Aggregates ...... 36 C5.2.1 Grading and Impurities ...... 36 C5.2.2 Durability ...... 37 C5.2.2.1 Alkali-Silica Reactivity...... 37 C5.2.2.2 Alkali-Carbonate Reactivity ...... 38 C5.2.2.3 D-Cracking ...... 38 C5.3 Water ...... 40 C5.4 Chemical Admixtures...... 40 C6.0 Submission and Design Requirements ...... 41 C6.1 Concrete Mixture Proportioning ...... 41 C6.2 Concrete Production Facility Certification...... 42 C6.3 Concrete Materials ...... 42 C6.4 Temperature Control Methods...... 42 C6.5 Crack Control Methods ...... 42 C6.6 Curing...... 44 C7.0 Quality Management ...... 45 C7.1 Quality Assurance ...... 45 C7.2 Quality Control ...... 45 C8.0 Production of Concrete ...... 46 C8.1 General ...... 46 C8.2 Equipment...... 46 C8.3 Measurement of Materials...... 46 C8.4 Mixing ...... 46 C8.5 Temperature Control ...... 46 C8.5.1 Cold Weather ...... 47 C8.5.2 Hot Weather ...... 47 C8.5.3 Control of Temperatures ...... 49 C8.6 Trial Batches and Mockups ...... 50 C8.7 Site Addition of Materials ...... 51 C8.8 Delivery Tickets ...... 51

v ABOUT THE AUTHORS Michael A. Caldarone, P.E., is Principal Engineer, Materials Consulting for CTL Group, Skokie, Illinois. He received his B.S. in Civil Engineering from the University of Illinois at Chicago. He has more than 20 years of broad expertise in materials engineering, with extensive experience in the commercial development, production and utilization of high- performance concrete. He is a registered professional engineer in Illinois.

Peter C. Taylor, Ph.D., P.E., is Principal Engineer and Manager of Materials Consulting for CTL Group, Skokie, Illinois. He received his B.Sc. and Ph.D. in Civil Engineering from the University of Cape Town in South Africa. He has more than 20 years experience in consulting and research specializing in materials performance and concrete durability. He is a registered professional engineer in Illinois.

Rachel Detwiler, Ph.D., P.E., F.A.C.I., is Senior Engineer at Braun Intertec Corp. in Minneapolis, Minnesota. She received her B.S., M.S., and Ph.D. from the University of California at Berkeley. She has over 20 years’ experience in consulting, research and development, specializing in concrete materials, performance and durability. She is a registered professional engineer in Minnesota, Illinois, and Wisconsin. Shrinivas B. Bhidé, Ph.D., S.E., P.E., is Manager of the Bridge Program at the Portland Cement Association. He received his Bachelor of Technology in Civil Engineering from the Indian Institute of Technology, Bombay, and Master and Doctorate degrees in Structural Engineering from the University of Toronto. He has over 18 years of experience in the design of buildings and bridges and is a registered structural and professional engineer in several states.

ACKNOWLEDGMENTS This publication was prepared for the Engineered Structures Department of the Portland Cement Association, David N. Bilow, Director, with funding through PCA research project 02-05.

The authors wish to thank the following individuals and organizations without whose help this publication would not have been possible: Caron Johnsen and Dale McFarlane, Portland Cement Association; and Arlene Zapata, Cheryl Taylor, and Deborah Render, consultants for the word processing, cover design, desktop layout and copy editing.

A Special thanks to Ron Burg, Construction Technology Laboratories who provided extensive input during the initial phase of the publication. Additional thanks for technical assistance, references, and editorial reviews goes to: Bruce Blair, Lafarge North America, Inc.; Bruce Carter, Hanson Permanente Cement; Bill O’Brien, Essroc Cement Corp.; Bill Asselstine, St. Marys Cement Inc. (Canada); Jim Wamelink, Axim Italcementi Group; H. Celik Ozyildirim, Virginia Transportation Research Council; Bijan Khaleghi, Washington State Department of Transportation; Paul Fossier, Louisiana Department of Transportation and Development; Ghulam Mujtaba, Florida Department of Transportation; Mary Lou Ralls, Texas Department of Transpor- tation; Jerry Potter and Lou Triandafilou, Federal Highway Administration; Henry Russell, Consultant; Concrete Corrosion Inhibitors Association; Slag Cement Association; Silica Fume Association; National Ready Mixed Concrete Association; Precast/Prestressed Concrete Institute; Rico Fung, Cement Association of Canada; Beatrix Kerkhoff, Jamie Farny, Terry Collins, Steve Kosmatka, John Melander, David Bilow, Basile Rabbat, and Paul Tennis, Portland Cement Association. Thanks also goes The Concrete Society, England for the use of the illustrations on types of cracks; ASTM, AASHTO, Joseph A. Daczko, Master Builders Inc. for the illustration on concrete flow requirements; Casimir Bognacki, the Port Authority of New York and New Jersey and Colin Lobo, NRMCA for providing the photos of the microwave water content test; John Gajda, CTLGroup, for providing the photos of thermal cracking in mass concrete; and ACI for the use of their material and documents referenced throughout the book. The authors have tried to make this Guide Specification for High-Performance Concrete Bridges a concise and current reference on HPC technology. Readers are encouraged to submit comments to improve future printings and editions of this book. Introduction

his document is intended to serve as a guide for developing specifications for high performance concrete for individual projects in all 50 states. It is intended to apply to all high performance concretes supplied for Thighway bridges, whether produced by a ready mix supplier, a general contractor, or in a permanent plant of a precast concrete manufacturer. For the purposes of this specification, high performance concrete (HPC) is considered as concrete that attains mechanical, durability, or constructability properties exceeding those of normal concrete. The specific meaning of “high performance” depends on the concrete property or properties under consideration, which may or may not include strength. Examples of HPC applications in bridges include:

A bridge deck in a northern climate must resist the ment and allow the contractor to propose the use of self- ingress of chloride ions and deicer scaling. If there is consolidating concrete. concern about the potential for cracking, a low modulus of elasticity and/or high creep might be specified, in A massive bridge pier or foundation must be designed to which case very high compressive strength might be limit stresses and cracking due to thermal gradients. If incompatible with the desired properties. Thus the speci- high strength, particularly high early strength, is specified fication should require a chloride ion penetration and for this application, the concrete will be more vulnerable scaling resistance. It should require only the strength to cracking. In this case, high strength is not consistent determined by the Engineer to be necessary for structural with high performance. The specification should not re- or operational reasons (e.g., for opening to traffic by a quire high strength except at later ages (56 or 90 days), certain time). since to limit cracking the concrete most likely will include relatively high percentages of supplementary A post-tensioned bridge girder could benefit from a high cementitious materials. modulus of elasticity and low creep to minimize deflections and loss of prestress. It most likely will have The above examples illustrate different criteria that might high strength as a consequence of these properties, or be specified for different applications within the same the designer may specify high strength to allow a more structure. The designer must select the criteria that are efficient design, with fewer girders to support the same important for the specific application. Specifying addi- load. The specification would thus include criteria for tional criteria beyond what is needed is likely to increase modulus of elasticity, creep, and compressive strength as cost, make it more difficult to meet the criteria that truly dictated by the structural design. are important, or result in unanticipated problems. For example, high strength, particularly high early strength, A pretensioned, precast girder may be made of self- frequently is achieved through an increase in the cemen- consolidating concrete. The specification could then titious materials content. The resulting heat generated include a slump flow as well as the modulus of elasticity, may increase the probability of thermal cracking even for creep, and compressive strength requirements. Alterna- sections of moderate size. Or for a bridge deck, for tively, the specification could omit a consistency require- example, the high stiffness, low creep, and high paste

1 Guide Specification for High-Performance Concrete for Bridges

content that usually accompany high strength may result 2.1 American Association of State High- in cracking due to autogenous or drying shrinkage. If way and Transportation Officials (AASHTO) high strength was not necessary, or was needed only at (www.transportation.org/aashto) later ages, cracking could be limited by appropriate adjustments to the mix design. AASHTO M 6, Standard Specification for Fine Aggregate for Portland Cement Concrete Some criteria (such as chloride penetration) are intended to be used for prequalification of a given mixture, while AASHTO M 80, Standard Specification for Coarse others (such as compressive strength and air content) are Aggregate for Portland Cement Concrete appropriate for use in quality control and acceptance tests. The commentary indicates which of these applica- AASHTO M 85, Standard Specification for Portland tions each criterion falls into. Cement AASHTO M 154, Standard Specification for Air-Entraining The intended user of this specification is an engineer working either directly for a state or local highway Admixtures for Concrete authority or other bridge owner, or for a contractor to a AASHTO M 157, Standard Specification for Ready-Mixed state or local highway authority or bridge owner. The Concrete user should be familiar with the characteristics of local materials. The user also should be aware of local dura- AASHTO M 194, Standard Specification for Chemical bility concerns that may necessitate special measures to Admixtures for Concrete prevent premature deterioration of the concrete. This document is intended to be modified by the user to suit AASHTO M 240, Standard Specification for Blended local conditions by inserting relevant clauses into the Hydraulic Cement contract specification and by inserting numerical values where required. AASHTO M 295, Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use as a The specification is accompanied by a Commentary that Mineral Admixture in Concrete provides explanatory notes, examples and guidance for the engineer and contractor in achieving the desired AASHTO M 302, Standard Specification for Ground properties. Granulated Blast-Furnace Slag for Use in Concrete and Mortars Note: Throughout this specification, AASHTO standards are given as primary, with the corresponding ASTM stan- AASHTO M 307, Standard Specification for use of Silica dard in parentheses. The two types of standards are not Fume as a Mineral Admixture in Hydraulic-Cement directly equivalent in every case. The user must select one Concrete Mortar and Grout or the other. Where only one is given, there is no corre- AASHTO T 22, Standard Method of Test for Compressive sponding standard. Strength of Cylindrical Concrete Specimens

AASHTO T 23, Standard Method of Test for Making and 1.0 Scope Curing Concrete Test Specimens in the Field This Specification covers the requirements for materials; methods for proportioning, mixing, transporting, placing, AASHTO T 24, Standard Method of Test for Obtaining finishing, and curing; and quality control and assurance and Testing Drilled Cores and Sawed Beams of Concrete of high performance concrete bridge elements. AASHTO T 27, Standard Method of Test for Sieve Analysis of Fine and Coarse Aggregates

2.0 References AASHTO T 96, Standard Method of Test for Resistance to This specification and its accompanying Commentary Degradation of Small-Size Coarse Aggregate by Abrasion refer to the following standards, specifications, and and Impact in the Los Angeles Machine publications. Publication dates deliberately are omitted from this listing; the user should refer to the most current AASHTO T 119, Standard Method of Test for Slump of version. Hydraulic-Cement Concrete

2 Guide Specification for High-Performance Concrete for Bridges

AASTHO T 121, Standard Method of Test for Mass per ASTM C 94, Standard Specification for Ready-Mixed Cubic Meter (Cubic Foot), Yield, and Air Content Concrete (Gravimetric) of Concrete ASTM C 131, Standard Test Method for Resistance to AASHTO T 126, Standard Method of Test for Making and Degradation of Small-Size Coarse Aggregate by Abrasion Curing Concrete Test Specimens in the Laboratory and Impact in the Los Angeles Machine AASHTO T 141, Standard Method of Test for Sampling ASTM C 136, Standard Test Method for Sieve Analysis of Freshly Mixed Concrete Fine and Coarse Aggregates AASHTO T 152, Standard Method of Test for Air Content ASTM C 138, Standard Test Method for Density (Unit of Freshly Mixed Concrete by the Pressure Method Weight), Yield, and Air Content (Gravimetric) of Concrete AASHTO T 160, Standard Method of Test for Length Change of Hardened Hydraulic Cement Mortar and ASTM C 143, Standard Test Method for Slump of Concrete Hydraulic-Cement Concrete

AASHTO T 161, Standard Method of Test for Resistance ASTM C 150, Standard Specification for Portland Cement of Concrete to Rapid Freezing and Thawing ASTM C 157, Standard Test Method for Length Change AASHTO T 196, Standard Method of Test for Air Content of Hardened Hydraulic-Cement Mortar and Concrete of Freshly Mixed Concrete by the Volumetric Method ASTM C 172, Standard Practice for Sampling Freshly AASHTO T 277, Standard Method of Test for Electrical Mixed Concrete Indication of Concrete’s Ability to Resist Chloride Ion Penetration ASTM C 173, Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method AASHTO T 318-02, Standard Method of Test for Water Content of Freshly Mixed Concrete Using Microwave ASTM C 192, Standard Practice for Making and Curing Oven Drying Concrete Test Specimens in the Laboratory

AASHTO PP 34, Standard Practice for Estimating the ASTM C 231, Standard Test Method for Air Content of Cracking Tendency of Concrete Freshly Mixed Concrete by the Pressure Method AASHTO LRFD, Bridge Design Specifications, U.S. 3rd ASTM C 260, Standard Specification for Air-Entraining Edition, 2004 Admixtures for Concrete AASHTO Quality Assurance Guide Specification, 1996 ASTM C 295, Standard Guide for Petrographic 2.2 American Society for Testing and Examination of Aggregates for Concrete Materials International (ASTM International) ASTM C 403, Standard Test Method for Time of Setting (www.astm.org) of Concrete Mixtures by Penetration Resistance ASTM C 31, Standard Practice for Making and Curing Concrete Test Specimens in the Field ASTM C 441, Standard Test Method for Effectiveness of Pozzolans or Ground Blast-Furnace Slag in Preventing ASTM C 33, Standard Specification for Concrete Excessive Expansion of Concrete Due to the Alkali-Silica Aggregates Reaction

ASTM C 39, Standard Test Method for Compressive ASTM C 457, Standard Test Method for Microscopical Strength of Cylindrical Concrete Specimens Determination of Parameters of the Air-Void System in Hardened Concrete ASTM C 42, Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete

3 Guide Specification for High-Performance Concrete for Bridges

ASTM C 469, Standard Test Method for Static Modulus ASTM C 1202, Standard Test Method for Electrical of Elasticity and Poisson’s Ratio of Concrete in Indication of Concrete’s Ability to Resist Chloride Ion Compression Penetration

ASTM C 494, Standard Specification for Chemical ASTM C 1240, Standard Specification for Silica Fume Admixtures for Concrete Used in Cementitious Mixtures

ASTM C 512, Standard Test Method for Creep of ASTM C 1260, Standard Test Method for Potential Alkali Concrete in Compression Reactivity of Aggregate (Mortar-Bar Method)

ASTM C 595, Standard Specification for Blended ASTM C 1293, Standard Test Method for Determination Hydraulic Cements of Length Change of Concrete Due to Alkali-Silica Reaction ASTM C 618, Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete ASTM C 1567, Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of ASTM C 666, Standard Test Method for Resistance of Cementitious Materials and Aggregate (Accelerated Concrete to Rapid Freezing and Thawing Mortar-Bar Method)

ASTM C 672, Standard Test Method for Scaling ASTM C 1582, Standard Specification for Admixtures to Resistance of Concrete Surfaces Exposed to Deicing Inhibit Chloride-Induced Corrosion of Reinforcing Steel in Chemicals Concrete

ASTM C 779, Standard Test Method for Abrasion ASTM C 1602, Standard Specification for Mixing Water Resistance of Horizontal Concrete Surfaces Used in the Production of Hydraulic Cement Concrete ASTM C 856, Standard Practice for Petrographic 2.3 U.S. Department of Transportation, Examination of Hardened Concrete Federal Highway Administration (FHWA) ASTM C 944, Standard Test Method for Abrasion (www.fhwa.dot.gov) Resistance of Concrete or Mortar Surfaces by the FP-03, Standard Specifications for Construction of Roads Rotating-Cutter Method and Bridges on Federal Highway Projects

ASTM C 989, Standard Specification for Ground FHWA High Performance Concrete Tool Kit, U.S. Granulated Blast-Furnace Slag for Use in Concrete and Department of Transportation, Federal Highway Mortars Administration, Publication NO. FHWA-RD-97-097, 30 May 1997. ASTM C 1012, Standard Test Method for Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate 2.4 American Concrete Institute (ACI) Solution (www.aci-int.org) ASTM C 1017, Standard Specification for Chemical ACI 121R, Quality Assurance Systems for Concrete Admixtures for Use in Producing Flowing Concrete Construction

ASTM C 1064, Standard Test Method for Temperature of ACI 201.2R, Guide to Durable Concrete Freshly Mixed Portland Cement Concrete ACI 207.1R, Mass Concrete ASTM C 1074, Standard Practice for Estimating Concrete ACI 207.2R, Effect of Restraint, Volume Change, and Strength by the Maturity Method Reinforcement on Cracking of Mass Concrete ASTM C 1105, Standard Test Method for Length Change ACI 207.4R, Cooling and Insulating Systems for Mass of Concrete Due to Alkali-Carbonate Rock Reaction Concrete ASTM C 1157, Standard Performance Specification for Hydraulic Cement

4 Guide Specification for High-Performance Concrete for Bridges

ACI 209R, Prediction of Creep, Shrinkage, and 2.5 Portland Cement Association (PCA) Temperature Effects in Concrete Structures (www.cement.org) ACI 211.1, Standard Practice for Selecting Proportions for PCA EB001, Design and Control of Concrete Mixtures Normal, Heavyweight, and Mass Concrete PCA IS415, Guide Specification for Concrete Subject to ACI 211.2, Standard Practice for Selecting Proportions for Alkali-Silica Reactions Structural Lightweight Concrete 2.6 Precast/Prestressed Concrete Institute ACI 211.3R, Guide for Selecting Proportions of No-Slump (PCI) (www.pci.org) Concrete PCI MNL-116, Manual for Quality Control for Plants and Production of Structural Precast Concrete Products ACI 211.4R, Guide for Selecting Proportions for High- Strength Concrete with Portland Cement and Fly Ash PCI MNL-133, Bridge Design Manual

ACI 224R, Control of Cracking in Concrete Structures PCI TR-6-03, Interim Guidelines for the Use of Self- Consolidating Concrete in PCI Member Plants ACI 232.1R, Use of Raw or Processed Natural Pozzolans in Concrete PCI TM-103, Quality Control Technician/Inspector Level III Training Manual ACI 232.2R, Use of Fly Ash in Concrete

ACI 233R, Slag Cement in Concrete and Mortar 2.7 National Ready Mixed Concrete Association (NRMCA) (www.nrmca.org) ACI 234, Silica Fume in Concrete NRMCA Publication 190, Guideline Manual for Quality Assurance Quality Control ACI 301, Standard Specification for Structural Concrete NRMCA, Quality Control Manual ACI 302.1R, Guide for Concrete Floor and Slab Construction 3.0 Definitions ACI 304R, Guide for Measuring, Mixing, Transporting, and Placing Concrete Bridge: A structure including supports erected over a depression or an obstruction, such as water, highway, or ACI 305R, Hot Weather Concreting railway, and having a track or passageway for carrying traffic or other moving loads, and having an opening ACI 306R, Cold Weather Concreting measured along the center of the roadway of more than 20 ft (6.5 m) between undercopings of abutments or ACI 308, Standard Practice for Curing Concrete spring lines of arches, or extreme ends of openings for multiple boxes; it also may include multiple pipes, where ACI 308.1, Standard Specification for Curing Concrete the clear distance between openings is less than half of ACI 309R, Guide for Consolidation of Concrete the smaller contiguous opening.

ACI 318, Building Code Requirements for Structural Cementitious materials: Portland cements, blended Concrete cements, and supplementary cementitious materials (e.g., fly ash, slag cement, silica fume, and calcined clay) used ACI 345, Guide for Concrete Highway Bridge Deck in concrete and masonry construction. Construction Cold weather: A period when, for more than three ACI 363R, State of the Art Report on High-Strength consecutive days, the following conditions exist: (1) the Concrete average daily air temperature is less than 40°F (5°C) and (2) the air temperature is not greater than 50°F (10°C) ACI 363.2, Guide to Quality Control and Testing of High- for more than one-half of any 24-hr period. The average Strength Concrete

5 Guide Specification for High-Performance Concrete for Bridges

daily temperature is the mean of the highest and the Inspector: The Engineer’s or Owner’s authorized repre- lowest temperatures occurring during the period from sentative who is assigned to make detailed inspections of midnight to midnight. the quality and quantity of the work and its conformance to the provisions of the Contract. Consistency: The relative mobility or ability of freshly mixed concrete or mortar to flow; the usual measure- Mass concrete: A volume of concrete with dimensions ments are slump for concrete, flow for mortar or grout, large enough to require that measures be taken to cope and penetration resistance for neat cementitious paste. with the generation of heat and temperature gradients from hydration of the cementitious materials, and atten- Contract: The written agreement executed between the dant volume change. Owner and the Contractor that sets forth the obligations of the parties including but not limited to the perfor- Owner: The local, state, or federal highway agency or mance of the work, furnishing of materials and labor, other public or private entity that will take possession of and basis of payment. the bridge on completion or upon transfer.

Contractor: Any individual, partnership, corporation, or Quality assurance: The planned activities and system- joint venture with whom the Owner enters into agree- atic actions necessary to provide adequate confidence to ment for construction of the work under the contract the Owner and other parties that the products or services documents. will perform their intended functions. Quality assurance is a management tool. Creep: Time-dependent deformation due to sustained load. Quality control: Actions related to the physical characteristics of the materials, processes, and services which Curing: The maintenance of satisfactory moisture and provide a means to measure and control the characteris- temperature in concrete during its early stages so that tics to predetermined quantitative criteria. Quality control desired properties may develop. is a production tool.

Engineer: The registered engineer designated by the Self-consolidating concrete (SCC): Highly flow- Owner as the accepting authority responsible for issuing able, non-segregating concrete that can spread into the project specification or administering work under the place, fill the formwork, and encapsulate the reinforce- contract documents. ment under its own weight without any mechanical consolidation. Flowing concrete: Concrete that is characterized by a 1 slump greater than 7 ⁄2 in. (190 mm) while remaining Subcontractor: Any individual, partnership, corpora- cohesive. tion, or joint venture with whom the Contractor enters into agreement for construction of some portion of the High performance concrete (HPC): Concrete engi- work under the contract documents. neered to meet specific needs of a project; including: mechanical, durability, or constructability properties. Supplementary cementitious materials: Cementitious materials other than portland cements used Hot weather: A period when, for more than three in concrete and masonry construction (e.g., slag cement, consecutive days, the following conditions exist: (1) the fly ash, calcined clay, and silica fume). average daily air temperature is greater than 77°F (25°C) and (2) the air temperature for more than one-half of any Water-cementitious materials ratio (w/cm): The 24-hr period is not less than 85°F (30°C). The average ratio of the mass (or weight) of water to the mass (or daily temperature is the mean of the highest and the weight) of all cementitious materials in the concrete. lowest temperatures occurring during the period from midnight to midnight.

6 Guide Specification for High-Performance Concrete for Bridges

4.0 Performance Requirements 4.5 Modulus of Elasticity Laboratory tests conducted to ensure that the proposed The concrete shall meet the requirements for modulus of materials and the proposed mix proportions meet the elasticity as tested in accordance with ASTM C 469 and specified performance requirements shall be conducted shown in Table 1. Specimens may be either 4x8-in. by a laboratory accredited by AASHTO (or equivalent) for (100x200-mm) or 6x12-in. (150x300-mm) cylinders moist those tests (or in a PCI-certified plant for the compressive cured (100% RH at 73.4±3.0°F [23.0±1.7°C]) until age of strength and consistency tests). testing.

4.1 Abrasion Resistance Table 4.5-1 Required Minimum Modulus of Elasticity For bridge decks or surface courses, aggregates known Modulus of elasticity Age at test to polish shall not be used, or the coarse aggregate shall 28 days be tested according to AASHTO T 96 (ASTM C 131). The result shall not exceed______%. 56 days

4.2 Chloride Ion Penetration 4.6 Freeze/Thaw Durability 4x8-in. (100x200-mm) concrete cylinders shall be ______The concrete shall have a durability factor of at least cured to an age of ______and tested in accordance with _____% when tested in accordance with AASHTO T 161, AASHTO T 277 (ASTM C 1202). The charge passed in six Procedure A (ASTM C 666, Procedure A), except that the hours shall not exceed _____ coulombs. age at testing shall be 56 days. Specimens shall be prisms at least 3 in. (75 mm) but not more than 5 in. (125 mm) 4.3 Compressive Strength in width or depth and at least 11 in. (280 mm) but not The concrete shall meet all of the requirements given in more than 16 in. (400 mm) in length. Table 4.3-1 for compressive strength as tested in accordance with AASHTO T 22. Specimens may be either 4x8- 4.7 Scaling Resistance in. (100x200-mm) or 6x12-in. (150x300-mm) cylinders. The concrete shall have a visual rating not greater than __ when tested in accordance with ASTM C 672, except Table 4.3-1 Required Minimum Compressive Strengths that the specimens shall be ______cured to age ______Compressive Age at test for before commencement of the 14-day drying period. strength design strength Curing 4.8 Shrinkage The drying shrinkage of the concrete when tested in accordance with AASHTO T 160 (ASTM C 157) shall not exceed ______. Specimens shall be moist cured until the age of ______and shrinkage shall 4.4 Creep be monitored for 180 days thereafter. The baseline comparator measurement shall be taken at 24 hours The concrete shall meet the requirements for creep as after casting. tested in accordance with ASTM C 512. Specimens shall be 6x12-in. (150x300-mm) cylinders. Store at 50% RH at 4.9 Sulfate Resistance 73°F (23°C) until test. Age at loading, and maximum creep coefficient shall be as shown in Table 4.4-1. Load- The sulfate exposure for this Work has been determined ing shall continue for 180 days. to be ______. The combination of cementitious materials in the proportions proposed shall have Table 4.4-1 Maximum Creep Coefficient sulfate resistance at least equivalent to that of Type __ cement and the water-cementitious materials ratio shall Age at Creep not exceed ___. Curing loading coefficient Moist cure after de- molding until age 7 days

7 Guide Specification for High-Performance Concrete for Bridges

4.10 Consistency cluding supplementary cementitious materials incorpo- Concrete of conventional consistency — The rated in blended cement: concrete shall have a slump not less than ___ nor more • Fly ash or other pozzolans up to 25% by mass of than ___ as measured in accordance with AASHTO T 119 cementitious materials (ASTM C 143). • Slag cement up to 50% by mass of cementitious mate- Self-consolidating concrete (SCC)— The concrete rials shall be classified as self-consolidating concrete and shall • Silica fume up to 10% by mass of cementitious mate- be produced such that it can be placed and consolidated rials without vibration and without segregation. The slump • Mixtures of silica fume, fly ash or other pozzolans, and 1 flow shall be not less than ___ nor more than ___. slag cement up to 50% by mass of cementitious materials, with no more than 10% being silica fume and no 4.11 Alkali-Silica Reactivity more than 25% being fly ash The aggregates shall be evaluated for potentially delete- • Mixtures of fly ash or other pozzolans, and silica fume rious alkali-silica reactivity and mitigating measures taken up to 35% by mass of cementitious materials, with no if necessary, as described in Section 5.2.2.1. more than 10% being silica fume and no more than 25% being fly ash 5.0 Materials 5.2 Aggregates 5.1 Cementitious Materials 5.2.1 Grading and Impurities Portland cement shall conform to the requirements of Fine and coarse aggregates shall conform to the require- AASHTO M 85 (ASTM C 150) or ASTM C 1157 for the ments of AASHTO M 6 and M 80 (ASTM C 33), except specified type, including the optional requirement for that the soundness requirement shall be waived. early stiffening. Blended cement shall conform to the requirements of AASHTO M 240 (ASTM C 595) or ASTM 5.2.2 Durability C 1157 for the specified type, including the optional requirement for early stiffening. Supplementary cementi- Unless the performance history of the aggregate is tious materials not incorporated into the blended cement known, it shall be tested to determine its potential for: shall conform to the relevant standards as follows: • Alkali-silica reactivity • Fly ash and natural pozzolans shall conform to the re- • Alkali-carbonate reactivity quirements of AASHTO M 295 (ASTM C 618) for the • D-cracking specified class. • Slag cement shall conform to the requirements of An aggregate shall be considered to have an acceptable AASHTO M 302 (ASTM C 989) for the specified grade. performance history provided the field concrete made from it is at least 15 years old, the cementitious materials • Silica fume shall conform to the requirements of used are comparable (particularly with regard to alkali AASHTO M 307(ASTM C 1240). content and use of supplementary cementitious mate- For concrete exposed to sulfate attack, the proposed rials), and the exposure conditions are at least as severe combination of cementitious materials shall meet the as those in the proposed project. Petrographic examina- requirements of Section 4.9. tion of the field concrete by ASTM C 856 shall be conducted to verify satisfactory performance. A copy of the Concrete subject to applications of deicing salts shall be petrographer’s report shall be submitted to the Engineer. restricted to the following maximum limits on the total The aggregate shall be approved by the Engineer before quantity of supplementary cementitious materials, in- it is used in the project.

1 Aggoun, S., Kheirbek, A., Kadri, E.H., and Duval, R., Study of the Flow of Self-compacting Concretes, First North American Conference on the Design and Use of Self-Consolidating Concrete, 12-13 November 2002, Center for Advanced Cement-Based Materials, Northwestern University, Evanston, IL, pp. 259-265.

8 Guide Specification for High-Performance Concrete for Bridges

Test data for comparable aggregate from the same by ASTM C 1567 to limit the 14-day expansion to a quarry are acceptable for this purpose. maximum of 0.10%.

If any of these criteria cannot be met by an acceptable Data from past field performance and/or ASTM C 1293 field history, the aggregate must be tested as described tests using the same aggregate, if available, also may be in the following sections. used to demonstrate satisfactory performance.

5.2.2.1 Alkali-Silica Reactivity No substitution of any material in the concrete is If an acceptable field performance history is not available, permitted without testing to verify its performance with representative samples of siliceous fine and coarse aggre- regard to alkali-silica reaction. gates proposed for use on the project shall be evaluated petrographically in accordance with ASTM C 295 and by 5.2.2.2 Alkali-Carbonate Reactivity the mortar bar test, ASTM C 1260. Representative samples of fine and coarse aggregates comprised of calcitic dolomites or dolomitic limestones Aggregate evaluated in accordance with ASTM C 295 proposed for use on the project shall be evaluated petro- and determined to contain more than the following graphically in accordance with ASTM C 295. Aggregates quantities of reactive constituents, expressed as percent characterized by relatively large, rhombic crystals of by mass, shall be considered potentially reactive2: dolomite set in a finer-grained matrix of calcite, clay and • Optically strained, microfractured, or microcrystalline microcrystalline quartz shall be considered potentially quartz exceeding 5.0% reactive and shall be evaluated in accordance with ASTM C 1105 using the proposed cement-aggregate combina- • Chert or chalcedony exceeding 3.0% tions. Cement-aggregate combinations exhibiting mean • Tridymite or crystobalite exceeding 1.0% expansion values greater than 0.015% at 3 months, • Opal exceeding 0.5% 0.025% at 6 months, or 0.030% at 1 year shall be considered potentially reactive. • Natural volcanic glass in volcanic rocks exceeding 3.0% Aggregates found by the above measures to be Aggregate tested in accordance with ASTM C 1260 and potentially reactive may be used only when diluted with a exhibiting mean mortar bar expansions at 14 days greater nonreactive aggregate. The suitability of the mixture of than 0.10% shall be considered potentially reactive. aggregates shall be verified by ASTM C 1105 to result in Aggregates considered potentially reactive by either of mean expansions not greater than 0.015% at 3 months, the above methods may be further evaluated by ASTM C 0.025% at 6 months, or 0.030% at 1 year. 1293. Aggregates exhibiting expansions greater than 5.2.2.3 D-Cracking 0.04% at 1 year shall be considered potentially reactive. Aggregates exhibiting expansions no more than 0.04% For bridge decks that will be subject to freezing and and demonstrating no prior evidence of reactivity in the thawing, coarse aggregates shall be tested for field shall be considered innocuous. susceptibility to D-cracking unless their performance history is known. Test data or field performance data for If an aggregate is determined to be potentially reactive in comparable aggregates from the same quarry are accept- accordance with the above protocol, or if the field able for this purpose. Any of the following test methods performance of the aggregate indicates that it is reactive are acceptable: regardless of the results of any of the above tests, an • Washington Hydraulic Fracture test3 appropriate mitigation measure shall be specified. The effectiveness of the mitigation measure shall be verified

2 Guide Specification for Concrete Subjected to Alkali-Silica Reactions, Portland Cement Association, IS415, September 1998, 8 pages. 3 Janssen, Donald J. and Snyder, Mark B., Resistance of Concrete to Freezing and Thawing, SHRP-C-391, Washington, DC: Strategic Highway Research Program, National Research Council, 1994, 301 pp.

9 Guide Specification for High-Performance Concrete for Bridges

• AASHTO T 161 (ASTM C 666), extended to 350 cycles; The statement shall include the purchaser’s name, con- the durability factor is calculated from the expansion of tract number, concrete manufacturer’s name, mix design the specimens. number, primary and backup production facility locations, • Iowa Pore Index Test4,5 intended mix use, air content, and slump ranges for each intended use. Aggregates failing these tests shall not be used. 6.2 Concrete Production Facility 5.3 Water Certification Mixing water for concrete shall comply with ASTM C The manufacturer of the concrete shall submit a current 1602. certification of the concrete production facility, including the concrete production facility and delivery fleet as 5.4 Chemical Admixtures issued by the National Ready Mixed Concrete Association Chemical admixtures shall comply with AASHTO M 154 (NRMCA) for the plant(s) proposed for use. For concrete (ASTM C 260), AASHTO M 194 (ASTM C 494), or ASTM batched for or within a precast concrete plant, submit C 1017, as applicable. Corrosion inhibitors also shall be proof of current certification in the Precast/Prestressed tested in accordance with ASTM C 1582. Concrete Institute’s Plant Certification Program.

The manufacturer shall certify that all admixtures contain 6.3 Concrete Materials no purposefully added chlorides, and that the chloride Test data for all concrete-making materials shall be pro- ion content of the admixtures in the quantities proposed vided to the Engineer 60 days prior to the start of the is below the limits given by ACI 201.2 Guide to Durable Work. All materials shall be approved by the Engineer Concrete (0.01% by mass of cementitious materials). before being used in the Work. Samples of all concrete- making materials (aggregates, cementitious materials, water, and chemical admixtures) shall be provided when 6.0 Submission and Design requested by the Engineer prior to or during production Requirements of the concrete.

6.1 Concrete Mixture Proportioning 6.4 Temperature Control Methods The Contractor shall be responsible for concrete mixture During hot and cold weather, the methods to be used to proportioning. Concrete shall be proportioned to meet control the temperature of the concrete as placed and the performance requirements detailed in the contract the temperature of the in-place concrete during curing documents and Sections 4 and 5. shall be submitted to the Engineer by the Contractor. Methods to be used to control the core temperature and Concrete mixture proportions shall be designed in temperature gradients during curing shall be submitted conformance with ACI 211.1, 211.2, 211.3R, or 211.4R to the Engineer by the Contractor. Refer to Section 8.5 and verified by trial batches. for further details and to PCI MNL-116 for standard At least 30 days before delivery of the concrete, the procedures for precast concrete manufacturing plants. manufacturer of the concrete shall submit to the Engineer a statement detailing the materials, sources, 6.5 Crack Control Methods and proportions of materials to be used for each grade The method(s) to be used to control cracking due to of concrete to be supplied. No substitutions shall be shrinkage and/or thermal stresses shall be submitted to allowed without the approval of the Engineer, who may the Engineer. All concrete elements with smallest dimen- require a resubmission of test data. sion larger than 2 ft. (600 mm) shall require implementa- tion of method(s) to control thermal stresses.

4 Traylor, M.L., Efforts to Eliminate D-Cracking in Illinois, Transportation Research Record, No. 853, 1982, pp. 9-14. 5 Marks, V.J. and Dubberke, W., Durability of Concrete and the Iowa Pore Index Test, Transportation Research Record, No. 853, 1982, pp. 25-31.

10 Guide Specification for High-Performance Concrete for Bridges

The maximum acceptable crack width at the surface for shall be monitored by two recording thermometers structural elements, including decks, columns, beams, showing the time-temperature relationship per 200 ft (60 parapets, and abutments shall be ______in. (____mm). m) of bed. For girders, one thermometer shall be located at the center of gravity of the top flange and one at the The Contractor shall inspect unformed concrete surfaces center of gravity of the bottom flange. For piles, one and identify and record the width, depth, and density (in thermometer shall be located midway between the linear feet per square foot or linear meters per square outside corners of the pile and the nearest edge of the meter) of cracks after removal of burlap or curing tarpau- center void. If there is no void, only one thermometer lins. Results shall be reported to the Engineer. shall be provided at the center of gravity of the cross section. Initial application of heat to accelerate curing 6.6 Curing shall begin only after the concrete has reached its initial Curing shall be in accordance with FHWA FP-03, Stan- set as determined by ASTM C 403. When used, steam dard Specifications For Construction of Roads and Bridges shall be at 100% RH. Application of heat shall not be on Federal Highway Projects, Section 552.15, and ACI directly on concrete. Concrete temperature shall be in- 308R, Standard Practice for Curing Concrete. In the event creased at a rate not exceeding 40°F (22°C) per hour of a conflict between the two documents, FP-03 shall until the desired concrete temperature is reached. The take precedence over ACI 308. concrete temperature shall not exceed ___°F (___°C). The Contractor shall submit written descriptions of the Heat curing may continue until the concrete has reached method(s) to be used for the curing of all bridge ele- the release strength. The Contractor shall detension ments to the Engineer for review and approval. Hot- and strands before the internal concrete temperature has cold-weather curing practices shall be employed when decreased to 20°F (11°C) less than its maximum weather conditions warrant (see definitions of hot and temperature. cold weather). See Section 6.4 for temperature control requirements. In addition, if cracks appear on the surface 6.7 Quality Control Plan of the concrete during construction, placement shall be See Section 7.2 for the description of the Quality Control discontinued until corrective measures are implemented. Plan to be submitted by the Contractor to the Engineer.

Curing shall begin within 15 minutes or 6 ft (1.9 m) of final finishing. 7.0 Quality Management

For concrete to be used in the bridge decks, barrier rails, 7.1 Quality Assurance approach slabs, and barrier slabs, the Contractor shall comply with ACI 302.1R and ACI 308R. If silica fume, fly The Owner or Owner’s representative shall prepare and ash, or slag cement is used, the Contractor shall limit carry out a Quality Assurance Plan to assure that the final finishing operations to screeding, bull floating, and product will perform its intended function. The Quality grooving. Continuous fogging above the surface of the Assurance activities shall not relieve the Contractor of concrete shall be used during the finishing operation and Quality Control responsibilities under the terms of the maintained until the concrete surface can support wet Contract. The Quality Assurance Plan documents the burlap without deformation. Free-standing water shall not Owner’s quality objectives. At a minimum, the Quality be permitted on the surface of the concrete prior to final Assurance Plan shall include the following: set. As soon as the surface of the concrete will support • Owner’s policy statement wet burlap or cotton mats without deformation, the Contractor shall apply wet burlap or wet cotton mats to • Quality objectives the textured concrete surface. The concrete shall remain • Scope of work under the Quality Assurance Plan continuously wet with a fog nozzle system or soaker hoses for 7 days and until a compressive strength of 3200 • Organization and reporting relationships psi (22 MPa) is reached. The use of polyethylene sheeting • Authority and responsibilities of the various or plastic-coated burlap blankets shall not be permitted. organizations and contractors

For concrete intended for use in prestressed concrete or • Description of overall quality assurance system, includ- when strengths are in excess of 6000 psi, temperatures ing which organizations are required to establish and implement quality assurance programs

11 Guide Specification for High-Performance Concrete for Bridges

7.2 Quality Control ▲ Personnel qualifications Before the start of the work, the Contractor shall submit | Document the name, authority, relevant to the Engineer a written Quality Control Plan in accor- experience, and qualifications of person with dance with Section 153 of FHWA FP-03, “Standard Spe- overall responsibility for inspection system. cifications for Construction of Roads and Bridges on | Document the names, authority, and relevant Federal Highway Projects,” or for precast concrete manu- experience of all persons directly responsible for facturers certified under the PCI Plant Certification Pro- inspection and testing. gram, submit applicable sections of the plant Quality System Manual. The Quality Control Plan shall include : ▲ Subcontractors: Include the work of all subcontractors. Provide details of how each subcontractor will • Process control testing: fit into the overall organization of the project, in- ▲ Materials to be tested. cluding lines of communication and authority be- ▲ Tests to be conducted. tween contractor and subcontractors, and among subcontractors. ▲ Location of samples extracted. ▲ Frequency of testing. The plan may be implemented wholly or in part by a Subcontractor or an independent organization. However, • Inspection and control procedures: the administration of the program, including compliance ▲ Preparatory phase with the plan and its modifications, and the quality of | Review all contract requirements. the work, remain the responsibility of the Contractor. | Ensure compliance of component materials to The Contractor’s Quality Control program shall be well contract requirements. managed and the testing results shall be representative | Coordinate all submittals. of actual operations. All quality control tests, inspections and approvals shall be documented by the Contractor | Ensure capability of equipment and personnel to and shall be kept on site for the use of the Contractor’s comply with contract requirements. personnel and shall be immediately available to the | Ensure preliminary testing is accomplished. Owner’s personnel for quality assurance and audit pur- | Coordinate surveying and staking. poses. The Quality Control Plan shall contain sufficient detail to serve as a reference summary and schedule for ▲ Start-up phase all quality testing, inspection and approval processes | Review contract requirements with personnel carried out by the Contractor and its agents. who will perform the work. No portion of the work shall begin until after the Quality | Inspect start-up of work. Control Plan covering that portion of the work has been | Establish standards of workmanship. accepted by the Engineer. | Provide necessary training. | Establish detailed testing schedule based on 8.0 Production of Concrete production schedule. ▲ Production phase 8.1 General | Conduct inspection during construction to iden- The volume of material in the mixer shall not exceed the tify and correct deficiencies. rated mixing capacity of the drum.

| Inspect completed phases before Owner’s sched- Proper facilities shall be provided to enable inspection uled acceptance. of the quality and quantity of the materials and the | Provide feedback and system changes to prevent processes used in the manufacture and delivery of the repeated deficiencies. concrete. The inspector shall be provided with all reason- ▲ Description of records: List the records to be able facilities for securing samples to determine whether maintained.

12 Guide Specification for High-Performance Concrete for Bridges

the concrete and its component materials are being minutes after introduction of the mixing water to the supplied in conformance with the specification. cementitious materials and aggregates.

Mixers shall be emptied of wash water and returned 8.2.3 Agitating Equipment concrete before charging with a new batch of concrete. The entire contents of the mixer shall be discharged Concrete that is completely mixed in a stationary mixer before recharging. may be transported in agitator trucks or truck mixers. The equipment shall be operated at the speed of rotation 8.2 Equipment designated by the manufacturer of the truck as the agitating speed. The concrete shall be discharged at the The concrete production facility and transport equipment site, without segregation, in a thoroughly mixed and shall conform to the certification requirements of the uniform mass, so as to meet the uniformity requirements National Ready Mixed Concrete Association, the PCI Plant of AASHTO M 157 (ASTM C 94). Except as specified for Certification Program, or equivalent. Documentation of hot weather concrete, and unless approved by the the certification shall be provided to the Engineer on Engineer, discharge of the concrete shall be completed request. within 11⁄2 hours after introduction of the mixing water The concrete production facility shall have either radio or to the cement and aggregates. telephone communication with the placement operation personnel. 8.3 Measurement of Materials Measurement of all constituent concrete-making mate- All mixers shall be capable of combining the ingredients rials used shall be in accordance with AASHTO M 157 of the concrete into a thoroughly mixed and uniform (ASTM C 94). mass, and of discharging the concrete so that the within- batch uniformity requirements of AASHTO M 157 (ASTM When there is evidence of inaccurately produced batches C 94) are met. of concrete, recalibration of the scales and admixture dispensers may be required. 8.2.1 Within-Batch Uniformity When ice is used as part of the mixing water, the ice shall Mixing equipment used shall produce uniform concrete be measured by mass. in accordance with the requirements of AASHTO M 157 (ASTM C 94). 8.4 Mixing The minimum sample size for determination of within- Mixing equipment shall comply with AASHTO M 157 batch uniformity shall be 1 cu ft (30 liters). Samples for (ASTM C 94). uniformity determination shall be taken after discharge Mixers shall be rotated at the speed recommended by of approximately 15% and 85% of the batch. the manufacturer of the mixer.

8.2.2 Non-Agitating Equipment Mixing time shall be measured from the time that all con- Concrete that is completely mixed in a stationary mixer crete ingredients are in the mixing unit. The minimum may be transported in non-agitating equipment. The mixing time for concrete shall be as recommended by the bodies of such equipment shall be smooth water-tight equipment manufacturer or the minimum time required steel containers equipped with gates that permit control to produce concrete meeting the uniformity acceptance of the discharge of the concrete. Covers shall be used to criteria of AASHTO M 157 (ASTM C 94), whichever is protect the concrete during inclement weather. The con- greater. crete shall be discharged at the site, without segregation, in a thoroughly mixed and uniform mass so as to meet Unless otherwise indicated by the mixer manufacturer, the within-batch uniformity requirements of AASHTO M when a truck mixer is used for complete mixing and is 157 (ASTM C 94). Unless approved by the Engineer, charged to its maximum rated mixing capacity, each discharge of the concrete shall be completed within 30 batch of concrete shall be mixed for not less than 70 nor more than 100 revolutions of the drum.

13 Guide Specification for High-Performance Concrete for Bridges

After completion of mixing, the truck mixer drum shall heated to not more than 104°F (40°C). Provision must be be rotated at the designated agitating speed until made to ensure that the material is heated evenly before discharge of concrete commences. being placed in the mixer.

When a stationary mixer is used for partial mixing of 8.5.2 Hot Weather concrete prior to transferring to a truck mixer, the mixing time shall be no more than is required to intermingle the Hot weather (see Section 3.0 for definition) concreting ingredients. After transfer to a truck mixer, further mixing practices shall apply during hot weather (refer to defini- at the designated mixing speed shall be carried out. tion of “hot weather”). Precautions shall be employed when producing, placing, finishing, and curing the For concrete containing silica fume batched separately concrete to protect it from the effects of hot weather. from the cement (that is, not a component of blended Method(s) to be employed to control the concrete place- cement), the silica fume shall be added to the aggregate ment temperature shall be submitted to the Engineer by with the cement. Silica fume shall not be placed first in the Contractor. Method(s) to be used to monitor weather the mixer. Silica fume shall not be added to the mixer in conditions during concrete placement, control plastic pulpable bags. shrinkage cracking, and control the concrete temperature and temperature gradients during curing shall be 8.5 Temperature Control submitted to the Engineer by the Contractor. The concrete temperature at the time of discharge from When ice is added to the concrete, it shall be completely the truck shall be at or between 50°F (10°C) and 90°F melted by the time the concrete mixing is completed. (32°C). The temperature of the cementitious materials Unless approved by the Engineer, when the air tempera- shall be less than 150°F (65°C) immediately prior to ture exceeds 82°F (28°C) and the concrete temperature batching. During curing, the maximum concrete temper- exceeds 77°F (25°C), concrete delivered by means of ature shall not exceed _____°F (_____°C) and the mini- agitators or truck mixers shall be discharged within 1 hr mum temperature of concrete shall not fall below 50°F after the introduction of the mixing water. (10°C). Plastic shrinkage control procedures shall be employed 8.5.1 Cold Weather when the evaporation rate of the freshly placed concrete During cold weather (see Section 3.0 for definition), exceeds the bleeding rate. Method(s) to be used shall special precautions shall be employed when producing, effectively reduce the rate of moisture loss from the placing, finishing and curing the concrete to protect it concrete surface or replenish moisture to the surface lost from the effects of cold weather. Method(s) to be used to evaporation. Fog spraying, if used, shall be at a rate to control the concrete placement temperature shall be sufficient to maintain a sheen of moisture on the surface, submitted by the concrete supplier. Method(s) to be used but no ponding of water. Excess moisture shall not be to control the concrete temperature and temperature finished into the concrete. Allow the water to evaporate gradients during curing shall be submitted by the just prior to finishing. Contractor. 8.5.3 Control of Temperature Differences Water brought into direct contact with the cementitious materials shall have a temperature less than 104°F Unless it can be demonstrated by engineering analysis (40°C). The concrete production facility shall have a that it is not detrimental to the structure, the maximum water temperature indicator installed such that the batch temperature differential between the interior and exterior operator can ensure that the temperature restrictions are concrete shall be limited to 35°F (19°C). For precast prod- met for each batch. Provision shall be made for heating ucts that use the addition of heat to accelerate curing, aggregates in the concrete production facility storage the maximum cooling rate for products that have bins. Aggregates shall be free of ice, snow, and frozen achieved transfer or stripping strength is 50°F (28°C) lumps before being placed in the mixer. The temperature per hour. Standard practices should be followed for of concrete shall not be less than 50°F (10°C) at the time transferring products from forms to storage that have of placement. The mix water and/or aggregates may be demonstrated acceptable results.

14 Guide Specification for High-Performance Concrete for Bridges

8.6 Trial Batches and Mockups the load of concrete. Water shall not be added to the Laboratory trial batches shall be made as a condition of load of concrete at any time. final approval of the mix design. All specified properties OR: The amount of water added shall be recorded on the shall be verified in accordance with the test methods concrete delivery ticket. In no case shall the total amount prescribed in Section 4. of water in the concrete be such as to exceed the speci- In addition, the Contractor shall be responsible for fied water-cementitious materials ratio. conducting a field trial batch of the concrete. At least 60 Water-reducing admixture may be added to the concrete days prior to placing high performance concrete, a full- when the measured slump is less than that specified. size trial batch of concrete shall be produced and tested. Field trial batches of concrete shall originate from each Air-entraining admixture may be added to the concrete production facility that will be used to supply the con- prior to discharge to increase the air content to that spe- crete. Trial batches shall be delivered to the site of the cified. The use of air-detraining admixtures is expressly work as directed by the concrete purchaser. When the prohibited. concrete is delivered in a ready mixed concrete truck, the volume of the trial batch shall be the volume of concrete Site introduced admixtures shall be added to the batch normally supplied by the truck. Field mockups shall be by means of a pipe or wand that can introduce the constructed as required by the Engineer to verify all tech- product to the center of the drum using an automated niques to be used for transport, placement, consol- metering device. Only trained personnel shall be allowed idation, finishing, and curing of the concrete member. to introduce admixtures at the jobsite. A method statement by the contractor for the site addition of admix- When an approved ready mixed concrete operation is tures shall be submitted and a record of jobsite additions currently supplying or has supplied a class of concrete shall be maintained and available at the project site at within the last ____ months requiring comparable perfor- all times. mance, permission may be granted by the Engineer to use the concrete mixture proportions from that operation When any material is added to the concrete, the concrete without the need for the full range of laboratory or field batch shall be mixed for an additional 30 revolutions (or trial batches provided that: more if necessary) at the designated mixing speed so that • There is no change in the source of any material. the uniformity requirements of Annex 1 of AASHTO M 157 (ASTM C 94) are met. In this situation it is permis- • There has been no significant change in quality of the sible to exceed the maximum of 100 revolutions total. concrete-making materials. The uniformity shall be monitored before placement of • The proposed concrete mix design meets all specified the concrete. requirements. • The conditions of field placement are substantially the 8.8 Delivery Tickets same as for the previous job. With each batch of concrete, the concrete manufacturer shall provide to the Contractor a copy of the delivery • Documentation of all test data is submitted to the ticket, on which shall be printed, stamped, or written the Engineer. following information: The Engineer shall indicate in writing which tests are not • Name of concrete manufacturer, and name or number required. of concrete production facility 8.7 Site Addition of Materials • Serial number of delivery ticket When a truck mixer is used at agitating capacity no ad- • Date justment shall be made to the load of concrete. • Class or designation of the concrete • Truck number EITHER: When a truck mixer is used for mixing of the concrete, no water from the truck water system shall be • Name of Contractor added after the initial introduction of the mixing water to • Name and address of project

15 Guide Specification for High-Performance Concrete for Bridges

• Time of batching, or of first mixing of cementitious materials and aggregates • Time at which concrete discharge must be completed • Moisture corrections for aggregate moisture • Quantities of each mixture component • Total batch volume • Maximum water that may be added to the mix at the project • Quantities of materials added at the site, including water and admixtures, if any • Specified compressive strength (or other specified performance criterion)

16 Commentary on Guide Specification for High-Performance Concrete for Bridges

C1.0 Scope C2.0 References The Guide Specification provides appropriate wording to specify each of the following criteria for high performance C3.0 Definitions concrete: abrasion resistance, chloride ion penetration, compressive strength, creep, modulus of elasticity, freeze/ thaw durability, scaling resistance, shrinkage, sulfate resis- C4.0 Performance Requirements tance, consistency, and alkali-silica reactivity. For a given bridge element, it is anticipated that the specifier will Specify only the performance grade required for each select at most four criteria. The performance criteria are characteristic, as additional requirements add to the cost given in Sections 4.1-4.11 of the specification, with guid- of the material without necessarily providing additional ance in the corresponding sections of the Commentary performance benefits. In some cases, high performance for modifying these criteria to suit local conditions. by one criterion may even detract from the performance by another criterion. FHWA recommendations for the Table C1.1 summarizes how to select criteria for various application of HPC Grades are shown in Table C4.0 for bridge elements. Table C1.2 summarizes the test methods reference. In some cases these differ from the recom- and standards discussed in this guide specification. mendations of this guide specification.

Note that FHWA’s default age at test is 56 days. For certain jobs, other ages, or accelerated curing regimes, may be more appropriate to specify either in addition to or instead of 56 days. If so, they must be explicitly specified. Examples are given in the following sections.

17 Guide Specification for High-Performance Concrete for Bridges . y s o a n t - a s t g t t i ) m o s c s n r ( s d o e e e j o e f e n d t b g m g a s l e a l u a . e a i ) a l h r h s e s r i o t t y a ( r d l l l s u i u s r u n y t a m o q s i f s e a c a r i s r t e e o e c l e u ) r e a r s p t d e t f n h t t ( l x t a e a p s u e h t u e s ...... f t e s s m y a y y y y y y y f , o g r f f f f f f f h r b i i i i i i i s m o o t n u e c c c c c c c k t u t t g t e d s y e e e e e e e i r s a o t a n e d r i i t p p p p p p p s . u . t r e e s n s s s s s s s i g w i r g e s g e t n t t t t t t t t m y s i d n n v o n s n m f i i i o o o o o o o a . i n e r s p t e k z s i c e s n n n n n n n m h u e x c r o e e t c e m r g o e r c g a / i o o o o o o o e e r . o p r e o r u n f n s f w c i H f d c g F D D S D D D I D D i s t i a e m - i l m d r . g n y l n e t 7 n . o . i o i u i . h y l t 7 r e t g s i s . r g t s l o r t a n i e i a s 2 n a r e y b u n b i o n e e g i t f o r n a g i ) i m i o z l a T i k o i , r r s s e f o c r m e t r i ( i c c s c f e i n e w e , t a e t t o e O p r a e t o s r d o c v e p r e r s a l T e n g f m g t s e l s l e e c c l r y c o u l e y a a i a H a t w o a f , l h f f i n e o i n l i r S y o t r t t r m f y a e m a d o c l - s a n u a t p i e A i m e s t r d n c t r e s e g r m v s c i c o e a u m c a A r t c p p e r d n t s e e i a i e c e t s t l e u ) j S s / e i a e p m o r n s a s i l r t r f n h t m b o i t . ( g p l r l i t x o w t c l h a l s r u u n h a a u o t s n a . . f t o s e r t f t s s s e i d o y y y y r o o i e o l y i o g a f f f t m t h u i n s t b i i i m f s k o o m t i t n o n i d c c c a o a k t t . e b y y a l a c g e d s n t s b . o f f s e e e r t d ) i u r i i e i n n e . d d e c e e s r t l n r b p p p s c c r r d ( t p m e o e e e s n s s s l a o o o i e e i c r s r m o a e o e s s y i u s a s t l t t t t t t y s , p p i n e l u , y g , o o s m f a n r r s s s c a r f o o o s a i m a o i i e e r r i p p r i p i e o e e r r c e n n n c o r v h c l t e y y u x x b x t t e u r i c f r t e b g p e g t t a a r e e e a a a q c a e i o o o i e a e e p x g r c t a e p o e n f f f d i c p H s s d d f I M D P I S M D D I a m w m e r a v n e e i e r h - y m c l . f l g g a e a l 7 o p n n i i t e o 7 E o t l t l n r e n 2 y r o o o f e y d i i c r T t c p s t c d n . o s e n n n e c e a n l O i l p n e e o p a f b T s t t a b f t s c s - , r a e a i H a t o , s e e r s o S y w t s n t , w t d i n a o A o s d o l r l r o e l o y l l r n A t t p c o a o s i a s a a f t s t c r e n i t . t e c s s t d l m g o r s m s t e s h t e a l u d . . . . . t n u t n i a s s s i y y y y y g e l r o g e f f f f f s e m u s i e i i i i i m n i r o b t m i i t n i c c c c c t x . s m f l s p o c n n f e s e e e e e i a s e t e r o l e e l d o t t l n p p p p p e r o m f e e m m s r s a s s s s s o r t g m s i o e u t u t g r t t t t t t y y y t s l e n o s d f f f e n i c c l o o o o o e e i i i m u r a p i r o e a n c c c n n n n n E d l d c x g x r p c m e f e e e r t e e r o a g i e o o o o o e p f r p p p n o e a f g m d t t o o D S D D I G S p S D D m o t d c i a r h f y , w g t a l r B . o e r g o n r y o k l i y e h a s l n t h o f a r c t i t k i e c l c u A e u c l n a c f M i n e a a m w i s n a d t f h u e o T s f o h s a r ) n i o i e p S g d p o t r c y s s e h i r E i s ( e t s s t o W A c o a i h h k l e e , o r d t m i n s r r w t ; s s i d m i n g b l n t t f c b o r o o h l l n a o l a e e f c a t h o a a a t r e p p m g g w s s y r d g y . s u i u g f e u g f n o i w o n n e a b h l g g d i n i d f i t c e n i a o e . t i m r c r n n a r e i r k o o i i t ) t z n a 1 n e c x m c r g s p c c s s o o o n e i i 6 i o ( p a s n a u e T T i l e . i o v e e . . 1 r r r h n S r a r . . i c y y m t 7 a m c d f d m e g y y f f d e i u a T t o o g l i i f f 7 h y i g t s y i i r t h n o o o o i c c r r . e n u f i 2 f a a t c c t t t t i O v i c e e e k e b o a e e c r r T T m e c c m n e i c p p d d d l t e e p p t . o e , s s r m o H e e e s a s s c f a y i a p u g O h r s s s e d n S t u s t t s n t . t t i y t r T y b n a u o o o g a f i i i A c i o o a , f g e 2 o o t i e m i r i r r H t p p p k y i n k r c t n n c c t n A h 7 n n i c s x x x b e S x c a c s i t C u v e e t n n 6 r e r e e e a a s a i e r a r o o A o o a f l p r r o o t t p p o e f f f f h c s h s C A s e I f D S D D I I I D D m c r c s o c c i h s c i W e t c e n 1 y s f w v n i n - i a c o a o r I e e s o a c e 0 e y n i i h c c . s e s y l t n t c y g e e h i i t t T e n n m 1 t l t u i t a / s a o n i i r d c l r g e i a a s r - i v g e C c k i a i t i t t s t b p r a u p i n o l t s z t s s i n n a t r a e a f e e i o i l d s i a c f e s r l n r m i e l r r s l s a n e a k o r a s e a l b h o u o r b e e e h c u e l t h r e e r R r E P A C C C M F S S S C A P D S c R a T

18 Guide Specification for High-Performance Concrete for Bridges

Table C1.0-2. Test Methods and Standards Discussed in this Guide Specification

Application AASHTO ASTM Other Test methods Abrasion T 6 C 131, C 779, C 944 Chloride penetration T 277 C 1202 Compressive strength T22 C39 Cracking pp 34 Creep C 512 Modulus of elasticity C 469 Freeze thaw T 161 C 666 Salt scaling C 672 Shrinkage T 160 C 157 Sulfate resistance C 1012 ACI 201 Slump T 119 C 143 Slump flow, J-ring, column SCC consistency segregation C 1293, C 1260, C 1567, Alkali silica reaction C 295 Alkali carbonate reaction C 1105, C 295 Iowa Pore Index Test, D-cracking T 161 C 666 Washington, Hydraulic Fracture Test Air content C 231, C 457 Air void analyzer Water content T 318 Cement content C 1084 Materials specifications Water M 157 C 1602 Cement M 85, M 240 C 150, C 595, C 1157 Supplementary cementitious M 295, M 302, M 307 C 618, C 989, C 1240 materials Aggregates M 6, M 80 C33 Chemical admixtures M 194, M 154 C 494, C 260, C 1582 Ready-mixed concrete M 157 C94 Quality QA QC systems ACI 121, 363 AASHTO QAGS FHWA FP-03 NRMCA Publication 190 PCI MNL 116

19 Guide Specification for High-Performance Concrete for Bridges l l o a , t , y , t n t r i s i s t o c c i d h p t t u e s e d d n a i R l o o v l r e i a p d m d n i i e d n s F 8 ) e a b ) ) p r 3 0 ) 1 i . — m y a a u h a l 6 s s t t c 0 P P t P b - i m 0 a . p g c t / a s i n 1 > M G n M e x a i j f 0 k 0 0 1 / e x i x e r x o x t 0 * 1 7 8 1 2 0 ≤ t r h 4 . . . 4 n ≥ > s 6 9 4 3 P > ≥ r 2 a 0 0 7 0 1 n o u e % 0 0 ≥ > ≥ ≤ i 0 5 F ≤ ≤ ≥ ≤ > ≥ q g 0 . 0 0 . x y x x . 3 9 d ( ( 9 0 5 x x y x 4 x 1 ( x ( i n e e r e a g B d d c a a a t e t r t r a s e G e h g r s t t t c l h e a s i n ) t t c c i o i i n n t m n s m ) ) s C s r ) u o i a p a a p o r a e m / r f P P m e c P r o m 6 1 0 . t % i 7 n 0 r e c , 0 G M 2 M s 0 0 n 2 s 0 a i p . / 6 0 a o y 1 2 5 0 0 5 k 1 r 9 f e a 0 0 . . 8 6 7 m y a t 4 4 r r t d a * 3 0 1 4 9 4 > e h < 2 e o > a < r c ≥ 1 f 6 m x 7 ≥ p r > > < < c x x y t 5 < < 5 0 x e e s n x x x x x i ≥ t r < 1 1 C P ≤ l y x ≥ ≤ o . . e o > P r s x ≥ ≥ ≤ > ≤ f h 0 0 0 C ≤ ≤ 8 0 c e H g 0 % 0 l i d n ≤ 5 0 0 3 1 0 9 o ≤ ≤ a . . 0 0 0 . 0 5 e o H d 5 4 5 6 A r r c ( 2 1 x x 2 1 6 0 8 1 6 ( ( ( t u u I m c a t W . o c , t r H h i e f u c l F b r t i s p t a t h l S x m s u m e a e s h r x i . c i e t d o e s e ) l ) s R n ) n , r g p u a a p a a f / 0 o n a o o P P P o 6 8 F 0 o h t m % i m s i s 0 . M G 3 M r 5 0 n s ) 0 . / s r c e o o 1 1 0 0 i 1 0 6 e t 8 i e f k . 9 0 1 5 . t m t t 6 l s t r i e * 2 6 4 5 1 i a > m < t r 0 e r > m a u ≥ b c n l e x 1 6 ≥ P < > > < . x t u x n a 0 0 0 - u x s c n v x o x x x x ≥ < < i h 5 2 1 ≤ a ≥ , d c E . . r g > t 1 e x x ≥ ≤ ≤ ≥ > i 0 s 0 6 0 a r d d i 2 . % 0 0 h s ≥ u H o n o ≤ ≤ 5 0 5 4 0 5 ≤ ≥ ≤ c c e . 0 5 . 0 . . a o i r 5 7 3 x m r n ( ( 7 2 5 3 x x 8 8 ( 2 x 0 ( e g h o n o o c s f c i t o t e g t n i s a l t a e a a c h p t a c i t l i . m a m t i f m r i s c s d r p a i d c c o e r i o s . f r e e m t k e r A d r e s s p c e o i e h t e e t s r d e o t C e p c e h b e r h o p o r e , s t a i c . d c l u m l d r o c h l i e r K n e a d b t e a a r u r i . o p e u b e h s m g a c n c p i e M C h d d s e m o l i n d c , e t 2 r n h e u h s o l t 9 0 1 7 s t b c P a l t h o e o s 2 2 e 1 2 6 6 7 c a d r n h o h t d n e 0 7 4 2 1 1 9 2 6 3 a t 1 2 1 1 2 e T i s d f a i a t e 2 5 4 9 7 4 0 6 1 6 4 r a o . s m e T T T T T w T w r 1 1 9 3 6 4 1 4 5 6 1 m r p c t d G d i o r o s r o p t l d d i a f O O O O O f l d o f s C C C C C C C C C C C a e n i r f T T T T T 1 r n m r e a e e r d p 6 a u e H H H H H d v p , M M M M M M M M M M M e e t i n c 4 . , a S S S S S s s m c T T T T T T T T T T T P r e e a , s C o a n S S A A A S A S A S S S S S S S u t g c f b n e r l . h e l n o s A A A A A A S A A A A A A A A A A a t o a h i p H o a h t s t e t , y c r m a e m s s i b t a p r t o m d s r i s r s e e r d a o f m i e r e h r e e p t r o i t d ) 8 s c t l s n f l g t c e G i c i i e l a i u O f n i r y l n c f f a ) i a n r . t a d i c z r l ) e u r s ) , s e a t u d a n ) w u T p O s i d s p h c e n y t s s o % r o y , f t s e o u t o l c e c . i r a s e , f w o s g e o i p u c t d A r m u n e d y i t n h f m o d c r n s t p t . g n t o r n i e c o y o n s s s a p l a 6 R i g r r t e i i e f P m r e e d a i n ) o t e , 5 s p l e c i r h r b r o s e v m u c o m a t t e i l i e g n t e e t A t a p e a d % t l t n ) a s r h d / ) m r p a a e l c g a c o f e r i c s a r n a c a , ) W k v e n n r u ) t n n x n n t i o i i m y a e d o = s i i p n n n s l u M d r e s f s d a i a H t e a a e s n i d e e r s c c t r s o o t b y l o , m r r r n c a s e e i i F . e e s f y s t t D h u e c t r i e s s , e i r w . l e o y n r s s s c m p a g C y a . G m s r s t l v e a 1 n n p p d u i i c a p o o e P c e o a S e . l e - a i e n p l t . a a r r 0 m h r i i l r d r n h y g e H e h m i 0 t b H u c c a l t u m - o m p e p t 0 0 U . b t o i i l - s a o i s d 2 u , r c b g e i n v x x n i o o n - i , l 3 5 4 a l o e g e c k i t l s e a r p e t i r a v e c m s e c m m e o n o l e k z r A t C r r i r n ) e n t a a v f e r o l n i a s d i s f e e s r l e e e r s r l t e ======e e a s W f o k i a t t r r m g e l a s s l b h r f r e f h c l f u t r i u h H o x x x x x x x x x x x e e b ( a ( m ( ( ( a ( ( ( P F S A C A S W S ( E S C ( ( t d G R F T F A h a T 6 7 8 9 T

20 Guide Specification for High-Performance Concrete for Bridges

C4.1 Abrasion Resistance C4.2 Chloride Ion Penetration Abrasion resistance is significant for bridge decks that Resistance to chloride ion penetration is significant for will be subjected to the action of truck traffic or reinforced and prestressed concrete that will be exposed snowplows, and for bridge substructure elements that to chlorides. The most common sources of chlorides from will be in direct contact with ice floes, floating debris, the environment are deicing salts and seawater. Chlorides and boat or ship traffic. act as catalysts to the corrosion reactions.

In general, good abrasion resistance is achieved by the If the crack widths are controlled by providing crack use of high-strength concrete and a hard, abrasion-resis- control reinforcement as specified in the AASHTO LFRD tant aggregate. Proper finishing and curing of the Bridge Design Specifications, the ability of the concrete concrete surface are essential. Specifications are normally to protect the steel from corrosion depends on the based on requiring a given performance from the aggre- quality of the concrete and the cover thickness. gate and setting a minimum strength. Field tests of abrasion resistance are not commonly required except for A maximum limit of 1500 coulombs (ASTM C 1202) is troubleshooting and evaluation of rain-damaged appropriate for most bridge elements that will be surfaces. exposed to chlorides. Values of 1500 to 2500 coulombs would be appropriate for superstructure elements not Aggregates should be pre-qualified, either based on expected to receive chloride exposure on a continuing historical performance or by testing. ASTM C 33 imposes basis. However, note that if deck joints are located a limit of 50% mass loss in the Los Angeles Abrasion test directly over elements of the superstructure, eventually (AASHTO T 96) but this may be considered too high a the joints will leak and salt water will drain onto the value for high performance requirements. As indicated in superstructure. If possible, locate deck joints elsewhere. If Table C4.0, the FHWA provides criteria for field testing not, specify 1500-coulomb concrete throughout. This test according to ASTM C 944, which is similar to ASTM C is commonly used as an acceptance indicator. It should 779, Procedure B. It gives an indication of the relative be noted that the scatter on the test is large, therefore wear resistance of concrete. imposing a limit of less than 1500 coulombs may result in rejection of acceptable concrete

Figures C4.1-1. Los Angeles abrasion test (AASHTO T 96). Test measures degradation of aggregates resulting from a combination of abrasion, impact, and grinding in a rotating steel drum containing a specified number of steel spheres. As the drum rotates, a shelf plate picks up the sample and the steel spheres, carrying them around until they are dropped to the opposite side of the drum, creating an impact crushing effect. The contents then roll within the drum with an abrading and grinding action until the shelf plate picks up the sample and the steel spheres, and the cycle is repeated. After the prescribed number of revolutions, the contents are removed from the drum and the aggregate portion is sieved to measure the degradation as percent loss. (left: IMG16950, right: IMG16949)

21 Guide Specification for High-Performance Concrete for Bridges

Elevated curing temperatures increase the permeability and diffusivity of concrete even when they do not actually increase its porosity11. However, concretes containing supplementary cementitious materials are less sensitive to this effect than portland cement concretes12.

Virginia DOT has adopted an accelerated curing regime for use with mixtures containing supplementary cementing materials13. Specimens are moist cured for 7 days at room temperature, followed by 3 weeks moist at 100°F (38°C). This regime is Figure C4.2-1. Test setup for the rapid chloride permeability test reported to be equivalent to 6 months normal (RCPT), also called Coulomb or electrical resistance test (ASTM C temperature curing when tested in accordance 1202). This test method consists of monitoring the amount of electrical current passed through slices of cores or cylinders during a 6-h period. with ASTM C 1202. A potential difference of 60 V dc is maintained across the ends of the specimen, one of which is immersed in a sodium chloride solution, the C4.3 Compressive Strength other in a sodium hydroxide solution. The total charge passed, in coulombs, is related to the resistance of the specimen to chloride ion The required compressive strength(s) must be determined penetration. (IMG16975) by the Engineer to ensure that the structure is able to withstand the design load. If control of deflections and/or limitation of prestress losses is desired, explicitly specify Theoretically, cover thickness and concrete quality can be the modulus of elasticity and the creep. Do not use traded off against one another; however, most current strength as a surrogate for either of these properties. In models of service life for concrete structures do not in- particular, strength should never be used as a surro- clude all of the mechanisms by which chloride ions pene- gate for durability. Although the FHWA performance trate concrete10. Thus it would be prudent to maintain grades specify the age of 56 days at which the concrete the cover thicknesses given by the AASHTO LFRD Bridge is to be tested, it may be necessary to specify different Design Specifications and use high performance concrete ages for some tests, such as to allow for early opening to as needed to prolong the service life. traffic, or for de-tensioning the strand for precast pre- Class F fly ash, some Class C fly ashes, calcined clay, slag stressed elements. The Engineer should consider how a cement, and silica fume all improve concrete’s resistance given test age would affect the design calculations and to chloride ion penetration. However, all of these require the behavior of the structure. Compressive strength com- sufficient curing time to develop the favorable micro- monly is used for quality control and quality assurance. structure that is required. Reducing the water-cementitious In general, the use of supplementary cementitious mate- materials ratio improves the resistance to chloride ion rials reduces the early-age strength and increases the penetration for all types of concrete. For bridge decks, later-age strength of the concrete as compared with a latex-modified or other polymer-modified concrete portland cement-only concrete. However, highly reactive overlays are an acceptable alternative to lowering the pozzolans such as silica fume and calcined clay may w/cm ratio. produce comparable or even higher strengths at early ages. Class C fly ash may either increase or reduce early-

10 Hooton, R. D. and McGrath, P. F., “Issues Related to Recent Developments in Service Life Specifications for Concrete Structures,” Chloride Penetration into Concrete, RILEM, 1995, L.O. Nilsson and J.P. Olivier, Eds., pp. 388-397. 11 Detwiler, Rachel J.; Kjellsen, Knut O., and Gjørv, Odd E., “Resistance to Chloride Intrusion of Concrete Cured at Different Temperatures,” ACI Materials Journal, Vol. 88, No. 1, January-February 1991, pp. 19-24. 12 Campbell, Glen M. and Detwiler, Rachel J., “Development of Mix Designs for Strength and Durability of Steam-Cured Concrete,” Concrete International, Vol. 15, No. 7, pp. 37-39, 1993. 13 Ozyildirim, C., Permeability Specifications for High Performance Concrete Decks, Transportation Research Record 1610, Concrete in Construction, Transportation Research Board, 1998, pp. 1-5.

22 Guide Specification for High-Performance Concrete for Bridges

60 The choice of coarse aggregate type can limit the ulti- Moist-cured entire time 8 mate strength of high-strength concrete. If reductions in 50 the water-cementitious materials ratio do not result in In air after 28 days moist curing increased strength, use a different aggregate or reduce 6 40 In air after 7 days moist curing the maximum size of the same aggregate, with appropriate adjustments to the mixture proportions. In laboratory air entire time 30 4 C4.4 Creep Creep is the long-term deformation of concrete under 20

C sustained load. Where deflections must be limited or o C m o 2 p m prestress losses must be minimized, the Engineer should r p e 10 r s

e determine the allowable creep consistent with these s s i v s e i

v criteria. Where cracking must be minimized (as on a s e t r s e 0 0

t bridge deck subjected to deicing salts), higher creep is r n e g 0 7 28 91 365 n t h g Age at test, days desirable. Increasing strength and stiffness generally , t h 1 ,

0 decrease creep, although there is no direct relationship M 0

0 Figure C4.3-1. Compressive strength gain. P 14

a among them . Limits on creep may be imposed for p

s Concrete strength increases with age as long as moisture and a favor- i able temperature are present for hydration of cement. prequalification but are not commonly used for quality monitoring. The maximum limits for creep for each of the FHWA age strength, depending on its composition, fineness and grades are given in Table C4.0-1. These are based on curing conditions. loading at the age of 28 days, the age assumed in the Specify the latest age consistent with the requirements of CEB model. The Engineer may determine that some the project, as most supplementary cementitious mate- other age is of more interest. In that case, specify that rials usually take more time to develop the desired prop- age in addition to or instead of 28 days. Equations to erties. The later the specified age, the more flexibility the predict creep are given in ACI 209. Decreasing the concrete producer has to meet the requirements at a required creep coefficient will mean that compressive strengths will increase.

reasonable cost and without introducing other potential i a s P problems. p k r r e e p 1.5 p

10 s s h

Concrete strength, 28 MPa (4000 psi) t h t n n Ageo of loading i o l i l l i 28 days l i

m 1.0 m , , n i n i a 90 5 r a t r t s

s 28 (sealed) p 0.5 p

e 180 e e r e r C C

0 0 0 250 500 750 1000 1250 Age, days Figure C4.4-1 (left) Creep test. (IMG61175) (right) Relationship of time and age of loading to creep of two different strength concretes. Specimens were allowed to dry during loading, except for those labeled as sealed (Russell and Corley 1977).

14 Neville, A.M., Properties of Concrete, 4th Edition, 1996, New York: John Wiley & Sons, 844 pp.

23 Guide Specification for High-Performance Concrete for Bridges

C4.5 Modulus of Elasticity modulus of elasticity of the cement paste and strength of The required modulus of elasticity is determined by the the bond between paste and aggregate15. The strength Engineer. In general, it would not be specified at all ex- of the cement paste and the paste-aggregate bond are cept for members in which control of deflections is para- of major importance to the concrete strength, while the mount. A high modulus of elasticity is desirable in such strength of the aggregate matters only when it imposes applications as tall bridge piers and towers and for long an upper limit on the strength of the concrete. Stiff ag- spans where deflections must be minimized. A low mod- gregates such as basalt confer higher moduli than lime- ulus of elasticity is desirable when stresses (and cracking) stones, which in turn confer higher moduli than light- due to restraint of volume changes must be minimized. weight aggregates. Specifying the largest practical Limits on modulus may be imposed for prequalification maximum size of aggregate and a favorable grading can but are not commonly used for quality monitoring. increase the volume of coarse aggregate in a concrete mixture, which will tend to increase the modulus of elas- High modulus of elasticity usually accompanies high ticity when using an aggregate with a high modulus of compressive strength, although the two are not directly elasticity. However, increasing the coarse aggregate size proportional. The modulus of elasticity is dependent on may result in reduced strength in high-strength concrete the properties of the coarse aggregate and the propor- mixtures. tion of the aggregate in the concrete, as well as on the

f, MPa 1.664 4 8 10

2.76 10 20 40 60 80 100 50 7 f, MPa

1.5 ACI 318, Ec = 33 wc ˘ psi 6 Range for which ACI code 40 formula was derived 5

Ec (40,000 ˘ +1.0 x106) 145 1.5 -6 30 145 1.5 -3 E ( ) x10 1.5 E ( ) x10 c w 4 (wc /145) psi c w psi MPa

Martinez, Nilson & Slate Kluge, Sparks & Tuma 3 Light- Richart & Jensen weight Price & Cordon 20 concrete Hanson Hanson Shideler 2 Martinez, Nilson & Slate Carrasquillo, Nilson & Slate Kaar, Hanson & Capell Normal Perechio & Klieger weight Richart, Draffin, Olson & Heitman 10 concrete Pauw 1 Hanson Bower & Viesi f, psi Richart & Jensen 1000 2000 3000 4000 5000 60008000 10000 12000 14000 0 0 20 30 40 50 60 70 80 90 100 110 120 130 f, psi Note: f is the measured compressive strength of concrete.

Figure C4.5-1. Modulus of elasticity versus concrete strength (ACI 363, Figure 5.3)

15 Neville, A.M., Properties of Concrete, 4th Edition, 1996, New York: John Wiley & Sons, 844 pp.

24 %

, Guide Specification for High-Performance Concrete for Bridges % s , s s e s r t e s r t f s o f i o s

0.0125 p a attention to consolidation and curing practices. Recom- Load removed 0.08 P 0 mended total air contents as given in Table C4.6-1 may 0

0.0100 M 0 be used for quality assurance purposes; however, the r

Instantaneous recovery 0.06 1 e

r total air content should be correlated with the spacing

0.0075 p Creep recovery Creep strain e factor and specific surface as determined by ASTM C n p

i 0.04 a 0.0050 n 457, as it is not the total volume of air that confers dura- i r Irrecoverable creep t a bility. Consideration may be given to using the Air Void r S 0.02 0.0025 t Elastic strain Permanent set S Analyzer to monitor variability in the air void system in fresh concrete. 0 400 800 1200 1600 Time, days Tests such as AASHTO T 152 (ASTM C 231) and AASHTO T 196 (ASTM C 173) measure only the total air content Figure C4.5-2. Combined curve of elastic and creep strains showing amount of recovery. Specimens (cylinders) were loaded at 8 days of fresh concrete. The concrete should be tested at immediately after removal from fog curing room and then stored at the point of placement, as air can be lost during trans- 21°C (70°F) and 50% RH. The applied stress was 25% of the compres- portation (particularly pumping), placement, and sive strength at 8 days (Hansen and Mattock 1966). consolidation.

C4.6 Freeze/Thaw Durability Tests such as ASTM C 457 are used to determine parameters related to the quality of the air-void system, such Where concrete will be exposed to freezing and thawing as the spacing factor and specific surface in hardened under conditions of saturation or near-saturation, a dura- concrete. An air-void spacing factor of 0.008 in. (0.20 bility factor of 90% as determined by ASTM C 666 Pro- mm) or less and specific surface of 600 in2/in3 (24 mm2/ cedure A is recommended. Some authorities use limits mm3) or greater usually will result in satisfactory freeze/ between 80 and 95%. If concrete is not exposed to freez- thaw performance. The Air Void Analyzer may be consid- ing cycles, it is not necessary to specify a freeze/thaw ered for use in monitoring the variability of the air void durability grade. Limits on freeze/thaw durability may be system in fresh concrete, although its correlation with imposed for prequalification, but quality monitoring should C 457 tests is still to be proven. be based on measuring the air content of the mixture. It may be useful for purposes of control to determine the In general, freeze/thaw durability is conferred by the air content at the concrete plant. A correlation between presence of a finely distributed system of air voids air contents at the plant and the site may help prevent throughout the concrete, adequate strength, and proper rejection of loads or delays.

Figure C4.6-1. (left) Concrete beams (3x3x111⁄4 in.) in a freeze-thaw chamber. Specimens are repeatedly frozen and thawed in water and can be tested for changes in length, weight, and dynamic modulus of elasticity. ASTM C 666. Procedure A. (IMG2081) (right) ASTM C 457. Using a polished section of a concrete sample, the air-void system is documented by making measurements using a microscope. The information obtained from this test includes the volume of entrained and entrapped air, its specific surface (surface area of the air voids), the spacing factor, and the number of voids per linear distance. (IMG64241)

25 Guide Specification for High-Performance Concrete for Bridges

Table C4.6-1. Approximate Mixing Water and Air Content Requirements for Different Slumps and Nominal Maximum Sizes of Aggregates (ACI 211.1 Table 6.3.3).

Water, lb/yd3 of concrete for indicated nominal maximum sizes of aggregate

Slump, in. 3⁄8 in.* 1⁄2 in.* 3⁄4 in.* 1 in.* 11⁄2 in.* 2 in.*† 3 in.†‡ 6 in.†‡ Non air-entrained concrete 1 to 2 350 335 315 300 275 260 220 190 3 to 4 385 365 340 325 300 285 245 210 6 to 7 410 385 360 340 315 300 270 — More than 7* — — — — — — — — Approximate amount of entrapped air in non- 3 2.5 2 1.5 1 0.5 0.3 0.2 entrained concrete, percent Air-entrained concrete 1 to 2 305 295 280 270 250 240 205 180 3 to 4 340 325 305 295 275 265 225 200 6 to 7 365 345 325 310 290 280 260 — More than 7* — — — — — — — — Recommended average♦ total air content, percent for level of exposure: Mild exposure 4.5 4.0 3.5 3.0 2.5 2.0 1.5■★ 1.0■★ Moderate exposure 6.0 5.5 5.0 4.5 4.5 4.0 3.5■★ 3.0■★ Severe exposure** 7.5 7.0 6.0 6.0 5.5 5.0 4.5■★ 4.0■★

* The quantities of mixing water given for air-entrained concrete are based on typical total air content requirements as shown for “moderate exposure” in the table above. These quantities of mixing water are for use in computing cement contents for trial batches at 68 to 77ºF (20 to 25ºC). They are maximum for reasonably well-shaped angular aggregate graded within limits of accepted specifications. Rounded aggregate generally will require 30 lb (14 kg) less water for non-air-entrained and 25 lb (11 kg) less for air- entrained concretes. The use of water-reducing chemical admixtures, ASTM C 494, also may reduce mixing water by 5% or more. The volume of the liquid admixtures is included as part of the total volume of the mixing water. The slump values of more than 7 in. (175 mm) are obtained only through the use of water-reducing chemical admixture; they are for concrete containing nominal maximum size aggregate not larger than 1 in. (25 mm).

† The slump values for concrete containing aggregate larger than 11⁄2 in. (37.5 mm) are based on slump tests made after removal of particles larger than 11⁄2 in. (37.5 mm) by wet screening. ‡ These quantities of mixing water are for use in computing cement factors for trial batches when 3 in. (75 mm) or 6 in. (150 mm) nominal maximum size aggregate is used. They are average for reasonably well-shaped coarse aggregates, well-graded from coarse to fine.

♦ Additional recommendations for air-content and necessary tolerances on air content for control in the field are given in a number of ACI documents, including ACI 201, 345, 318, 301, and 302. ASTM C 94 for ready mixed concrete also gives air-content limits. The requirements in other documents may not always agree exactly, so in proportioning concrete consideration must be given to selecting an air content that will meet the needs of the job and also meet the applicable specifications.

■ For concrete containing large aggregates that will be wet screened over the 11⁄2 in. (37.5 mm) sieve prior to testing for air content, the percentage of air expected in the 11⁄2 in. minus material should be tabulated in the 11⁄2 in. (37.5 mm) column. However, initial proportioning calculations should include the air content as a percent of the whole. ★ When using large aggregate in low cement factor concrete, air entrainment need not be detrimental to strength. In most cases the mixing water requirement is reduced sufficiently to improve the water-cement ratio and to thus compensate for the strength-reducing effect of air-entrained concrete. Generally, therefore, for these large nominal maximum sizes of aggregate, air contents recommended for extreme exposure should be considered even though there may be little or no exposure to moisture and freezing. **These values are based on the criteria that 9% air is needed in the mortar phase of the concrete. If the mortar volume will be substantially different from that determined in the recommended practice, it may be desirable to calculate the needed air content by taking 9% of the actual mortar volume.

26 Guide Specification for High-Performance Concrete for Bridges

Care also should be taken to provide adequate drainage so that water does not remain on the surface of the concrete.

Figure C4.6-2. Bridge damaged by freeze-thaw attack. (IMG13301)

C4.7 Scaling Resistance Scaling resistance is necessary when the concrete will be subjected to deicing salts, in which case specify a visual rating of 1 or less as measured by ASTM C 672. If the Figure C4.7-1. Deicer-scaling specimens (3x6x15 in.) are frozen and concrete will not be exposed to de-icing salts, then no thawed with a salt solution on the surface. A mortar dike holds the specification for scaling resistance is necessary. Limits on solution in place. Specimens are rated by the degree of scaling (ASTM C 672). (IMG2082) scaling resistance may be imposed for prequalification tests, but acceptance monitoring should be based on measuring the air content of the mixture. C4.8 Shrinkage ASTM C 672 requires a moist curing period of 14 days Shrinkage of concrete, as described below, is related to before a 14-day drying period. It may be appropriate to moisture loss to the environment, or to consumption of specify a different curing period to reflect the curing water in the hydration process. These processes are anticipated in service. ASTM C 672 uses CaCl as the 2 cumulative; therefore reducing any one of them will deicing chemical unless a different chemical is specified. If the Owner routinely uses a different chemical for this reduce the total shrinkage of the system. purpose, the chemical used should be specified. There are no standard tests that measure total shrinkage Scaling resistance is obtained by a suitable air-void system from the time that the concrete is first mixed. AASHTO as described in Section C4.6, by limiting the water- T 160 (ASTM C 157) measures drying shrinkage after a cementitious materials ratio to a maximum of 0.45, by 28-day (or other specified period) moist cure. Typical incorporating a minimum of 564 lb/yd3 (335 kg/m3) of values are in the range 400 to 800 microstrain. Specifi- cementitious material, by limiting the proportion of sup- cations requiring lower values will be difficult to meet. plementary cementitious materials as discussed in Section This method does not include the effects of autogenous 5.1, and by proper attention to finishing and curing. Wait shrinkage or drying in the plastic stage, even though they until all bleeding has stopped before finishing the con- may be more significant causes of cracking in low water- crete so as to avoid trapping bleed water and creating a cementitious materials ratio concrete16. AASHTO provi- plane of weakness just under the finished surface. Avoid sional practice PP 34, “Practice for Estimating the Crack- over-finishing, which can remove air voids from the near- ing Tendency of Concrete,” (or ASTM C 1581) describes surface concrete where they are most needed. Avoid the a test method that indicates the cracking tendency from use of finishing aids, which consist primarily of water. the time of casting.

16 Holt, Erika E., “Where Did These Cracks Come From?” Concrete International, Vol. 22, No. 9, September 2000, pp. 57-60.

27 Guide Specification for High-Performance Concrete for Bridges

Total

Autogenous

Settlement Plastic Thermal Drying

Figure C4.8-1. Total shrinkage is a sum of the individual mechanisms. Minimizing any or all of the shrinkage mechanisms will reduce the risk of cracking.

cracking, the Engineer should rather specify the required curing procedures, inspection, and crack repair methods. In addition, the mix proportions of the concrete should be such as to maximize the aggregate content (since it is the paste that shrinks). Shrinkage-reducing admixtures (discussed in section C5.4) also may be used. The need to reduce paste content to reduce plastic and drying shrinkage, while increasing water cement ratio to reduce autogenous shrinkage, may be counter to the need for high strength and or low permeability of the system. “High performance” concrete is therefore likely to be at higher risk of cracking, meaning that greater care needs to be taken with detailing and workmanship. Figure C4.8-2. Ring shrinkage specimen marked where a crack has occurred. AASHTO PP 34 and ASTM C 1581 are restrained shrinkage C4.8.1 Plastic Shrinkage tests used to determine the effects of concrete variations on cracking Plastic shrinkage occurs when water evaporates from the tendency using concrete cast around steel. (IMG16976) surface faster than bleed water rises to the surface. Plastic shrinkage cracking therefore can be prevented by preventing the evaporation of water from the concrete. The best way to minimize both plastic shrinkage and In general, high performance concrete is particularly drying shrinkage is to reduce the paste content of the vulnerable to plastic shrinkage cracking because it mixture, and to pay proper attention to curing. A clause exhibits little or no bleeding. However, altering the mix limiting shrinkage determined using ASTM C 157 is proportions to encourage bleeding is not an appropriate included in the guide specification should the Engineer means to limit plastic shrinkage. require it for pre-qualification. However, to minimize

28 Guide Specification for High-Performance Concrete for Bridges

1. Measures to minimize the occurrence of plastic which the water-cementitious materials ratio is less than shrinkage include the following:Have sufficient about 0.4217. Shrinkage that takes place within the first personnel, equipment, and supplies available to place 24 hours of placement is of greatest concern because at and finish the concrete promptly. Cover the concrete these early ages the concrete has the lowest strain with wet burlap, polyethylene sheeting, or building capacity and is most vulnerable to cracking. paper, or use an evaporation retardant between finishing operations to prevent drying. Since no moisture loss is involved in autogenous shrinkage, efforts to prevent drying at the construction 2. Start curing the concrete as soon as possible. stage cannot prevent autogenous shrinkage. Concrete 3. Dampen the subgrade, formwork, and reinforcement mix proportions and ingredients will have the most signif- before placing concrete. icant influence. Measures to minimize autogenous 4. Use fog sprays, temporary windbreaks, and shrinkage include: sunshades as needed, especially under hot, dry, or 1. Minimizing the cementitious paste content (that is, windy conditions. maximizing the aggregate content). 5. Place concrete in the late afternoon or at night. 2. Increasing the water-cementitious materials ratio. 6. Synthetic fibers may help to control plastic shrinkage 3. Avoiding the use of large quantities of excessively fine cracking. cementitious materials.

4. Using cement with a lower C3A content.

Note that some of these measures may offset those needed to meet the strength and/or durability requirements.

Chemical shrinkage Subsidence Chemical Bleed water shrinkage Autogenous shrinkage Cumulative Water hydration voids Water Water

Figure C4.8.1-1. Typical plastic shrinkage cracks, caused by rapid loss Cement of mix water while the concrete is still plastic (IMG12267)

Cement Cement Hydrated C4.8.2 Autogenous Shrinkage cement

Autogenous shrinkage is the volume change that occurs Hydrated when there is no moisture loss to the surrounding cement environment. It takes place because the volume of the At casting At initial setting After hardening hydration products of cement is less than that of the Figure C4.8.2-1. Volumetric relationship between subsidence, bleed water, unhydrated cementitious material(s) and water from chemical shrinkage, and autogenous shrinkage. Only autogenous shrinkage which they form. It is most noticeable in concrete in after initial set is shown. Not to scale.

17 Holt, Erika E., Early Age Autogenous Shrinkage of Concrete, VTT Publication 446, Technical Research Center of Finland, Espoo, 2001, 194 pp. Also available through Portland Cement Association as LT257.

29 Guide Specification for High-Performance Concrete for Bridges

C4.8.3 Drying Shrinkage slender elements, drying affects long-term deformations Drying shrinkage occurs due to loss of moisture from the or prestress losses. However, the creep test (ASTM C 512) concrete after final set and continues to take place for includes the combined effects of drying and long-term weeks or months after placement. Concrete is particu- loading. larly vulnerable to the development of drying shrinkage Shrinkage reducing chemical admixtures are addressed in stresses immediately after formwork removal because its Section C5.4. tensile strength may be low and drying can be severe, particularly if the concrete temperature is greater than C4.9 Sulfate Resistance the ambient temperature. It is therefore important to ensure that concrete is prevented from rapid drying after Sulfate attack is particularly prevalent in arid regions formwork is removed, by means of applying curing where naturally occurring sulfate minerals present in soils compounds, fog sprays, wet burlap and/or shading. and ground waters are in contact with structures. In North America, these areas are located primarily in the Drying shrinkage is relevant to long-term deformations. It western United States and the prairie provinces of should be noted that massive elements such as piers dry Canada. The necessary conditions for sulfate attack are out very slowly, and that drying shrinkage therefore plays well established and preventive measures can be taken to an insignificant role in their long-term deformation. In provide the needed service life18.

Although the severity of sulfate attack generally is de- fined in terms of sulfate concentration in the soil or 0.1 groundwater, the cations present have a significant effect on the severity of attack, with magnesium sulfate the most aggressive, calcium sulfate the least aggressive, and 0.08 sodium sulfate of intermediate aggressiveness. %

, F) e (73° g C a 3° In sulfate-bearing soil or groundwater, use AASHTO M k 0.06 2 n

i 85 (ASTM C 150) Type II or Type V cement, AASHTO M r F)

h 0° (4 s 240 (ASTM C 595) Type IS or Type IP, ASTM C 1157 Type C

g 4°

n MS (moderate sulfate resistant) or Type HS (high sulfate i

y 0.04 r resistant) cement, or a combination of portland cement D Cement content with sufficient Class F fly ash, slag cement, and/or silica = 307 kg/m3 (517 lb/yd3) fume to provide the degree of sulfate resistance required 0.02 (ACI 201). In addition, limit the water-cementitious mate- ASTM C 157 rials ratio to the values shown in Table C4.9-1. This is a criterion that should be applied during pre-qualification. 0 0 8 16 24 32 40 48 56 64 There are no standard test methods to assess the sulfate Age, weeks resistance of concrete. ASTM C 1012 and ASTM C 452 Figure C4.8.3-1. Effect of initial curing on drying shrinkage of are methods used for testing cements. portland cement concrete prisms. Concrete with an initial 7-day moist cure at 4°C (40°F) had less shrinkage than concrete with an initial 7- day moist cure at 23°C (73°F). Similar results were found with concretes containing 25% fly ash as part of the cementing material (Gebler and Klieger 1986).

18 DePuy, “Chemical Resistance of Concrete,” Significance of Tests and Properties of Concrete and Concrete-Making Materials, STP 169C, Paul Klieger and Joseph F. Lamond, Editors, American Society for Testing and Materials, Philadelphia, PA, 1994, pp. 263-281.

30 Guide Specification for High-Performance Concrete for Bridges

1.0

Rating: 1.0 = no deterioration 5.0 = severe deterioration 2.0

ASTM Type I, A g n i

t ASTM Type II, a r 3.0 l ASTM Type V, a u s i V

4.0

Figure C4.9.1. Concrete deterioration due to sulfate attack. (IMG16953)

5.0 0.3 0.4 0.5 0.6 0.7 0.8 Water-cement ratio by mass Figure C4.9.2. Average 16-yr ratings of concrete beams in sulfate soils for three portland cements at various water-cement ratios (Stark 2002).

Table C4.9-1. Requirements for Concrete Exposed to Sulfates in Soil or Water

Maximum Sulfate (SO4) in Sulfate (SO4) in soil, % by mass water, ppm Cement type* w/cm- Sulfate ratio, exposure ASTM C 1580 ASTM C 150 ASTM C 595 ASTM C 1157 by mass Negligible Less than 0.10 Less than 150 No special type required —

IP(MS), IS(MS), Moderate P(MS), (includes 0.10 to 0.20 150 to 1500 II MS 0.50 I(PM)(MS), seawater) I(SM)(MS)

Severe 0.20 to 2.00 1500 to 10,000 V HS 0.45 Very severe Over 2.00 Over 10,000 V HS 0.40

* Pozzolans and slag that have been determined by test or service record to improve sulfate resistance may also be used. Adapted from ACI 318 (2005).

31 Guide Specification for High-Performance Concrete for Bridges

C4.10 Consistency Self-consolidating concrete (SCC) is not the same as conventional flowing concrete produced using a high- Monitoring consistency is a valuable tool for assessing range water-reducing admixture. A number of test the between-batch uniformity of concrete. It may be methods are under consideration by ASTM to charac- preferred to allow the contractors to choose a slump that terize the placement properties of SCC, including the is suitable for their equipment, and to impose a limit on “slump flow” test, “Column Segregation” test, and variability between batches. Consistency of normal con- “J-ring” test19. The slump flow test is conducted using crete is most commonly measured using the slump test.

Slump Flow Test is performed similar to the conventional slump test (ASTM C 143) using the Abrams cone (use of inverted cone possible). However, instead of measuring the slumping distance vertically, the mean spread of the resulting concrete patty is measured hori- zontally. This number is recorded as the slump flow. Measured characteristic: Filling ability (deformability) & stability.

J-Ring The J-Ring consists of a ring of reinforcing bar such that it will fit around the base of a standard slump cone. The slump flow with and without J-Ring is measured, and the difference calculated. Measured characteristic: Passing ability.

Column Segregation Test evaluates static stability of a concrete mixture by quantifying aggregate segregation. A column is filled with concrete and allowed to sit for awhile after placement. The column is then separated into three or four pieces. Each section is removed individually and the concrete from that section is washed over a No. 4 sieve and the retained aggregate weighed. A non-segregating mix will have a consistent aggregate mass distribution in each section. A segregating mix will have higher concentrations of aggregate in the lower sections. Measured characteristic: Stability.

Figure C4.10-1. QCQA tests for SCC. (IMG16973, IMG16972, IMG16971)

19 Assaad, J., Khayat, K.H. and Daczko, J., “Evaluation of Static Stability of Self-Consolidating Concrete,” ACI Materials Journal, Vol. 101, Issue No. 3, May-June 2004, pp. 207-215.

32 Guide Specification for High-Performance Concrete for Bridges

the slump cone as described in AASHTO T 119 (ASTM importance and must be controlled carefully for C 143); however, rather than measuring the vertical consistent results. subsidence or slump, the average diameter of the disk that spreads out on lifting the inverted cone is mea- The performance grade for consistency (Table C4.10-1) sured20. Typical flow values for SCC are in the range of should be specified as required to produce acceptable 20 to 30 in. (500 to 750 mm). consolidation. In most bridge members, it would be more appropriate to specify a slump of 3 to 4 in. Grades 2 and SCC mixtures usually contain a high-range water-reducing 3 are self-consolidating concrete, which may be appro- admixture either alone or in combination with a viscosity- priate for precast members or (for Grade 3) in repairs. It modifying admixture. To achieve desirable placement is recommended that the Engineer not specify a consis- properties, SCC mixtures may also incorporate higher tency performance grade but allow the Contractor to cementitious materials contents, low water-cementitious propose it if he desires. The Contractor must demon- materials ratios, and smaller sized aggregates. The aggre- strate adequate performance of the concrete as placed in gate grading and moisture content are of particular the trial batches and mockups.

Slump flow < 22" (550 mm) 22-26" (550-650 mm) > 26" (650 mm) Low Reinforcement level Medium High Low Element shape intricacy Medium High s c i

t Low s i r

e Surface finish importance Medium t c a

r High a h

c Low r e

b Element length Medium m

e High M Low Wall thickness Medium High Low Placement energy Medium High

= Not recommended; potential problem area.

= Recommended

Figure C4.10-2. Slump flow targets. Adapted from Constantiner and Daczko (2002)21.

20 Petersson, Orjan, et. al., Testing SCC, presented at First North American Conference on the Design and Use of Self-Consolidating Concrete, ACBM, Northwestern University, 2002. 21 Constantiner, D. and Daczko, J., “Not All Applications are Created Equal; Selecting the Appropriate SCC Performance Targets,” Conference Proceedings: First North American Conference on the Design and Use of Self-Consolidating Concrete, November 12-13, 2002.

33 Guide Specification for High-Performance Concrete for Bridges - r - . e n r , i e o e e . 7 a d f d r e 5 l h l p d 7 a e 2 s x u t e - g 9 . o t l a e o n 6 r 2 e o s o l g 2 c a e c p r . A l n n o a y 5 l M d r a g l h i i t i M l s a a d y r n l , 7 4 i t C T t 1 i n a f a n T C t l o s t P n n a i e e t w m 2 1 S a r r a S h t n a , e t n s c o o - r y a . n o e i i a C c o 2 i t e i o t t A c , i s l a e 7 p a 2 e u A t c x U l s v s r i s e . a s r . i m n s e d 2 o e e e d f t p C o . n m e t e i e . o m 3 e e s r d e c t n o , v v n s 2 a r r t o a t i f s i i p t p e s e t s 2 o , o o e r f o t a n t t i s . l n p k o p i i f s i a t n o s y e s b o r a h s C d . a a i l A e o , s s u c e x r o c l t d g d l o c e r t s p s e r s e n i n n c s 0 e i n o n t e b s — u e w o n i e l e r t y , r r d o A v r e A e r t r f l t c a v o 6 i a r y g e s r . o a i o a c g e e o e S r u t i a l . l e o c a s e g m t y p 2 l t t t n s u p l c d l k a c m n c s y s l l c s a r t l e s t C i c x n c n g o 1 n s o o o e u y p r u o a a r p a l n a r e e r l a r a e i U n f a e m a r n e c t n l y r t t m o d t . i r o c t t o o e a o g s s 4 C . g s l e o o i t c e f a e n c a a e r f s s f e o n g c m c e n c c t 2 n y a o , 3 n n r t c n i e r a s l a a i l g g l i r i o n r m e y m m e l a m s i 4 f f , i i 7 9 9 l p l e i a e u t a h e e n u a o r d n m l t t r a m r r u 7 9 c f t i r 2 8 2 p c i h r g d t p e y y a n t h c c m o t D m u c g g t e e q r r 9 n t 2 e 2 2 1 p s e d g e a a n o i e a a a i o m s o i s i o R o r r a e e e 9 i g g p o a p u e c h h h e e z n C s t S C p r s X c m t a w C s t a s G i C g U m g H S V R F r C U N V 1 , . n s o e - e - i s ; i , - t t g n h r o i r z e C e l f a t r a i - t l e i o % r l o s l f % i a c r t h o p i c i f i p t e a n t 0 u o i 4 s a t e i % c M t . o l f l a e p k e i o e 8 ; 0 l m s n u T % a 0 % e 3 a v e v . n u v w n s p , i n e a i e i S , q e v 5 2 a s 0 u , d t 0 - i a t t r u 8 . o A h y d t n 7 0 i h A a q c c m t e o g s y 9 . 1 l o s c w s t e n l c o e % a a r r t t s l i i n p f 9 d 0 f a o , o n n i n o t x i m e c 0 e a l l a i n d e v 1 o e f e n l . e i r r a o c e d e e ; u r p a t t t o e n l a f o r i o 3 o p i s i g n r e y y s y l i m f s t c n r a t t l y e x i m c e , s u , , l l s n a r e x i e n e . l s c e j r n o e i s e b h s y a n t v a e b u a n n a r C t i n i u o r a n k i i y u t % % i a s t o t n l m e o h r o c c o d l g o e s d i a r o d t 0 0 p u a e n p c o m — i o c o s e o a a i e s h t n t x c n t r 1 1 o e r N r , m t i s , r c c R i y . . n e s a p t a e i a e r c n n l r r n 1 l i d i n S 9 i o o c t a t c 0 0 • e p o t d e f f i r c a e o x a i n X 8 e r S p p x t ) A t ; i p l n m s d n n p u % r n n r e p i x 2 9 o e m , e x f e e a , O e a r l o q s r a a e x i 2 4 i t o e P e s i 5 % s v c d c a s e r e n i e . t h h o h l d C 0 e • 7 , s i 1 s 5 t e % . t t e s U p d e s u . c n y , o n t e 3 9 o : C t t c 4 n u l t i s 0 0 y . l r r l t n v a e e 0 s m 3 d 1 M n S 9 a m l a o o a a 2 a e i y a I e e a • i s i 2 o e u p e u i , . T m i i e 4 l t r 1 t t i o p 3 e g r l n t s t r d t , r t ; d i t g r y i S p S e c 0 a m a a o e e a 9 I n m t u n r r n c a t r n r e n r n m i t d e y e e s 1 , t A A s i t i p c 2 l a , e e o % r r n e e e u t n x k e s e g r i c 9 s s t 8 l t t i n r e r n n 1 t c p h a t 0 g g e a k d T O a w g a r n . l t e u e o 1 t x x e e o e o o o a a r a h e o f f i o c o t a e d t o C e m d r I C A P S P p 6 I P c m c f 5 l g • • i c t m o s c s a o s x d , n d h e e s K A n n n e o i g r R d d c i r i r a i s t o o y t e e d i i a h e o y r r ) p r r n P t t a l t s t n p a a e d o o o — u u a a n e a d h t t l l e t t g i l a C C c e e r r r n c g i r s s n m ° ° s o o n t p t f i y o o a m e p e e s s i a y 8 0 o a s s s a r ) ) t t a r n m ) n f r i C 3 6 g e F F m m u g e e a x c r m m a F c ° i ° g o v d e t t t g f f n n s s i e s ° s d a r i i w i i a e 6 s 6 — a a l l i o o r r m A 0 , n n F g c s r m 7 d 7 s e - a a y i r r r m a p p i 0 o g t l e e l i n n u 1 1 k k d p p e e a l l n ) t r ( ( 1 s t a v m a t t — e e o o h r n ( f t o o F b a a i i a u a t t s k o a a o s s a ( ) ° o c c l s s C C o r p e e e e n r r r s s C F a e n n l l P l i ° ° r r 4 f w w A d v a i i e t ° ° . e e i o o c c a a t r p , e 0 0 s e t r r r r f m r 8 0 0 s s s d s r n n u u p d 8 8 . p r r c c m m a e e o i a m o s s i i 4 0 e l n a o o o i i 7 f a l a v v c t x t y t l a t e o 1 1 m m i m a 3 r s o s b a e g b T V I m M I C V C a o o ( ( o p t r a c t a d n - s g e - o e a r r - l n l n - l l R c ( - - i s C a e o n u o e x a a t t t a t i n r s r f i i s a o y r t e d l d t t e n n n i e n o s s g e o c t i r r t a i o a r f s i e e e n n n c n l i o n n t g c i h i i g o n r a o v u e e e a i a a s t o o f m a S m m f m h i t t g i i i n e v c - i e s b n l t i t t i e t l e e e i l i p o o i u d e R r l — n l t l r l c i a a a s c c c a i a a i S p p n o m c u i e a s o b r t a m o n n r t t a f f - r i y e i i k o o e d m A i e l e e a t g c n n r f l s e h t n o o c c i b b e f r t x s l s e h h n a a o g A a e R i c c t t t e r t t e m n n e o a g u k s s o m m g y t i l o t n - o o r n a o t o c o o p r n o i e e e e o o c e i t a i i e r i i a l D c i a e o p r p c c f p t s s v n n n c i p a i e n n g c i i i i s , h b l g d i i t t n n . t e m n e k i e e e n n u p e e l g r c r a a a t t d n e m m m a s e h t H h S m l l a a o o o a r r r a n t a t a a e g e s - r i p p i i u c i r t a l l p e e e i t r m s n e f x x i s r t e e g g n t g t l o t t t g r j a r r t p m a e s e s e e n o u e e e a o e u e e t v a o o b e p v e e r r e u n e a e r f s o d t i e e r d o t d d t k c s R R u i e n t t m d d r g g r r l p l a r t S S S u e a f e f a a e o n g x g m o o o o o o o S i e n n A a o i t m p a e i o a t b A a h P T T T T T A d T T p g e , t r a e o k r ) - f ) t - s i n - f d c i l i t i 3 l a s e e o r s n a - t t a 9 l S - s a c c d e e o k s m i i m a a n k l f t F a 2 c t - a e l s s o r i i s C a d t h h g a l i a o B t 1 n n a e i e o h r i i l e a l p r e p p s n t m n G r K e m p x e b - a n g o a a o C s e i i e m e i t r r c f g l r e g t t e e r s ) r v d e m c r i a g g g o n n t e o d ) M e u d n e p t n a M o t r g k a o o a e ( e P s l v d c u o a t o o c T r r t i r e a i i g e h f s e t t a , e o d s t t , S e c h t o f ) r h i a f c . D e s t o e e t h a f t e n P o u A 3 o e t f f e a T P P , e r c A E t t t n h y , i o c 0 e . c o o g y t t , 3 0 , x f e , d e s c i 7 i i x m t 3 r e 1 e n n i g 6 9 6 5 e e 1 v m c r e 6 n n e - c i i r v u m e o d o m n 5 2 2 9 t i f T e 4 t i g r 5 o o 1 n i a m c t e e d t i i g d e e c 8 1 1 2 p ( 4 a g l 1 t 1 t t a c o m c d r b c a n a . O S J a - e e b i a c c a a a f a o a f l n C C C C r - t t t e T C r 4 C , e n e e r n n f r o a d o a e e y o n i i e n r r - m H C i r l a r r t d o o i ( n n e t i l t M M M M r s M S n M e c c e t c a m m r a e r v a c a t u T T T T T n T c o n l s o n c n n c a A a a r e s i o i a i i k s S S c S S S S l l o o r F G b x t l x l e o o i i i i e o e m A m a t s s c ( e t T A A A A A a A s A ( p r a c m e f a 2 3 T 2 2

34 Guide Specification for High-Performance Concrete for Bridges

C4.11 Alkali-Silica Reactivity to use on a job in most cases, materials suppliers or state There are currently two ASTM test methods that use the highway departments already may have data on the actual job materials in combination. In ASTM C 1567, the performance of the proposed job materials. If so, these aggregates are crushed and sieved to a specified grading data may be used in preference to data from ASTM and mortar bars made using the proposed dosages of C 1260. This is a prequalification criterion. the proposed cementitious materials. The mortar bars are The basic premise of ASTM C 441 is that low-alkali submerged in a NaOH solution at 100°F (38°C) and the cement provides adequate control of expansions due to expansion after 14 days’ exposure is the criterion for alkali-silica reaction. This is not true of all aggregates. determining the effectiveness of the control measures. In Thus, the test may be used to compare the relative effec- ASTM C 1293, concrete prisms are made from the job tiveness of different combinations of cementitious mate- materials using the aggregates sieved and recombined to rials, but not to evaluate the acceptability of a given the specified grading. The specimens are stored over combination of cementitious materials. ASTM C 1567 is water in a closed container at 100°F (38°C) for two the recommended test method for that purpose. years. While the duration of this test makes it impractical

Figure C4.11-1. Cracking of concrete from alkali-silica reactivity. (IMG12421, IMG13049)

35 Guide Specification for High-Performance Concrete for Bridges

C5.0 Materials Particle size grading, together with the particle shape, determines the packing characteristics of the aggregate, C5.1 Cementitious Materials that is, its ability to fill space. Any space not filled with Cementitious materials when used in combinations aggregate must be filled with cement paste, which is should be evaluated to determine their effect on those typically more expensive than aggregate and is prone to concrete properties which the Engineer has determined shrinkage and thermal cracking. The most efficient to be significant for the project, including water demand, packing is obtained with rounded, equidimensional parti- setting time, heat development, strength development, cles of uniform grading. Sieve analyses for both coarse shrinkage characteristics, and early stiffening24. and fine aggregates should be performed according to AASHTO T 27 (ASTM C 136). The aggregate should meet the requirements of AASHTO M 6 and M 80 (ASTM C 33) except as noted.

Figure C5.2.1-1 provides a guide for the grading of the combined coarse and fine aggregates. Zone I mixtures tend to segregate during placement. Zone II represents the desirable range with the position of the dot and the surrounding region bounded by the parallelogram being the optimum. Zone III is an extension of Zone II of aggregates 0.5 in. (13 mm) and finer. Zone IV concrete would have too much fine mortar. Zone V concrete would be too rocky25.

Clays and silts can increase water demand in fresh con- Figure C5.1-1. Supplementary cementitious materials. From left to crete, increase drying shrinkage, impair paste-to-aggre- right, fly ash (Class C), metakaolin (calcined clay), silica fume, fly ash gate bond, and cause disruptive swelling within the (Class F), slag, and calcined shale. (IMG16974) hardened concrete. Organic impurities can adversely affect setting times and strengths.

C5.2 Aggregates The grading of the fine aggregate fraction is also important for an additional reason: Too little fines make the C5.2.1 Grading and Impurities concrete difficult to extrude and finish as well as more Proper grading of the aggregates is key to good worka- prone to bleeding, too much increases the water demand bility, low water demand, and efficient filling of the of the concrete and the required dosage of air-entraining volume. Efficient filling of the volume by aggregates admixture. For slip form paving, the minimum limit for (with the consequent minimization of paste volume) is the fineness modulus (calculated according to AASHTO important for maximizing stiffness (modulus of elasticity), T 27 (ASTM C 136) is 2.3. The fine aggregate should minimizing creep and shrinkage, and minimizing the have no more than 45% passing any one sieve and generation of heat of hydration. retained on the next consecutive sieve.

24 Kosmatka, Steven H.; Kerkhoff, Beatrix; and Panarese, William C., Design and Control of Concrete Mixtures, EB001, Portland Cement Association, 2002, 372 pages. 25 Shilstone, James M. Sr. and Shilstone, James M. Jr., “Performance-Based Concrete Mixtures and Specifications for Today,” Concrete International, Vol. 24, No. 2, February 2002, pp. 80-83.

36 Guide Specification for High-Performance Concrete for Bridges

45 t n e

t IV n o c s

u 40 o s i t e i t t a n II III g e e m r e g c g r a o f d 35 e d n i e t b s u m j I o d c a

, R r

e A o

v B t e c D i N a 30 s f RE 8 y T t . i l i o

b V N a g k r n i o s s W a 25 p t n e c r e P

100 80 60 40 20 0 Coarseness factor, combined aggregates Percent retained on No. 8 sieve that is also retained on 3/8" sieve

Figure C5.2.1-1. A satisfactory aggregate grading falls within Zone II on this plot.22

C5.2.2 Durability with the list of reactive constituents and their allowable limits. C5.2.2.1 Alkali-Silica Reactivity These guidelines are adapted from PCA IS415. In developing a quarry, aggregate producers may have obtained ASTM C 1293 data for their aggregate with The tests for aggregate reactivity may be performed in combinations of local cementitious materials. Such data any order. In general, ASTM C 1260 is considered conser- would be acceptable in specifying concrete for a partic- vative in that it may identify seemingly innocuous aggre- ular job. Some slowly reactive aggregates produce a gates as reactive. ASTM C 1293 is considered more “borderline” expansion value according to ASTM C 1293. definitive but takes a full year to identify aggregates as In this situation it is helpful to plot the expansion versus reactive and two years to verify the effectiveness of miti- time. If the slope of this line at the end of the test period gation measures. ASTM C 441 is not recommended indicates that the expansion is not leveling off, it is pru- because it does not represent the actual aggregate to be dent to specify some mitigation measure. In the absence used and because the underlying assumption that low- of these data or sufficient time to develop them, the alkali cement produces an acceptable result with all prudent course would be to rely on ASTM C 1260 to aggregates is not valid. identify the aggregate as reactive and ASTM C 1567 to select an appropriate mitigation measure. A range of When requesting an evaluation of the aggregate by combinations of cementitious materials could be tested ASTM C 295, it is helpful to provide the petrographer simultaneously and all acceptable combinations included in the job specification.

37 Guide Specification for High-Performance Concrete for Bridges

Mitigation measures include the use of pozzolans and/or The following procedures offered the best protection slag cement, either as a component of blended cement against the formation of popouts when reactive sands or as a separate addition at the concrete production are used26. facility. In some cases, the quantity of supplementary 1. In the hot summer months, wet curing is essential. cementitious material in blended hydraulic cement is not Wet curing should be initiated as early as possible. sufficient to control expansions due to alkali-silica reaction. Additional supplementary cementitious material, 2. Fresh concrete should be protected from drying either of the same or different kind, may be added to the before final finishing. blended hydraulic cement if necessary. As a guideline, 3. Hard-troweling should be avoided, if possible. Class F fly ash may require 15% to 25% by mass of total cementitious materials to meet the expansion criterion, C5.2.2.2 Alkali-Carbonate Reactivity while slag cement may require 40% to 50% and calcined Alkali-carbonate reactive aggregates are problematic only clay approximately 15% to 20%. Class C fly ash is not in limited geographical areas. The most conservative generally recommended for this purpose, as it may actu- practice is to avoid the use of reactive aggregates by ally increase expansions at some dosages. Ternary combi- selective quarrying. Reactive aggregates may be nations (using two supplementary cementitious materials) identified by testing in accordance with ASTM C 1105. also can be very effective.

It is essential to avoid making substitutions of one material for another on the job without testing. Fly ashes meeting the requirements of AASHTO M 295 (ASTM C 618) for Class F fly ash may be considerably different with regard to their effectiveness in controlling expansions due to alkali-silica reaction because of their contents of lime and/or alkalis, or because of their reactivity (a function of particle size and composition). Likewise, cements meeting the requirements of AASHTO M 85 (ASTM C 150) for Type I cement may require different dosages of the same fly ash to produce acceptable results with the same aggregate. If supplies are uncertain and it is anticipated that substitutions may have to be made during the course of the job, combinations of various possible job materials can be tested simultaneously to Figure C5.2.2.2-1 Micrograph showing cracks due to alkali carbonate determine which ones produce acceptable results. Then reaction (ACR) caused by argillaceous (clay-rich) dolomitic limestone all acceptable combinations may be listed in the specifi- aggregates. (IMG16952) cation and the final selection left to the Contractor or concrete producer.

In scattered areas of the Northern Great Plains, the C5.2.2.3 D-Cracking glacial sands containing shale particles can be susceptible D-cracking may be a concern for concrete subjected to to popouts caused by alkali-silica reaction. Found most freezing and thawing under conditions of saturation. It on hard-troweled surfaces, these popouts are much may be of relevance for some bridge decks, but not for smaller and shallower than those caused by absorptive other bridge elements. Generally, the larger the particle coarse aggregates. The popouts are very unusual in that size, the more susceptible the aggregate is to D-cracking. they often appear a few hours after the concrete is Aggregate susceptible to D-cracking must be either finished and, in most cases, within the first few weeks.

26 Landgren, R., and Hadley, D. W., Surface Popouts Caused by Alkali-Aggregate Reaction, RD121, Portland Cement Association, 2002.

38 Guide Specification for High-Performance Concrete for Bridges

rejected or beneficiated so that the particles of suscep- Nearly all rock types susceptible to D-cracking are of sedi- tible size are removed. The resulting reduction in the mentary origin. If the performance history of a proposed maximum size of the aggregate requires a concomitant aggregate is unknown and the concrete will be subjected change in the concrete mix design so that the proportion to freezing, the aggregate must be tested. The Washing- of aggregate is reduced and the proportion of cementi- ton Hydraulic Fracture test27 is the most direct method. It tious material is increased. This may increase the cost of requires a special apparatus in which surface-sealed the concrete. More important, the increased paste aggregate is placed in water. The vessel is subjected to content results in greater vulnerability to cracking due to 10 cycles of pressurization. The aggregate particles are increased thermal stresses and autogenous, plastic, and counted to determine an index of susceptibility to D- drying shrinkage. If there is an aggregate available that is cracking. AASHTO T 161 (ASTM C 666) tests the dura- not susceptible to D-cracking, it is prudent to use it. bility of concrete under cycles of freezing and thawing in conditions likely to saturate the concrete. Modifications for the purpose of testing aggregate for susceptibility to D-cracking include increasing the number of cycles to 350 and calculating the durability index from the expansion of the specimens. In the Iowa Pore Index Test28,29 the aggregate is sealed into the pot of an AASHTO T 152 (ASTM C 231) air meter. Water is added to a certain level in the transparent tube at the top of the pot. Air pressure is applied to force the water into the pores of the aggregate. The decrease in the volume is called the pore index. A high pore index indicates a nondurable aggregate.

Figure C5.2.2.3-1. D-cracking along a transverse joint caused by failure of carbonate coarse aggregate. (IMG12314, IMG12315)

27 Janssen, Donald J. and Snyder, Mark B., Resistance of Concrete to Freezing and Thawing, SHRP-C-391, Washington, DC: Strategic Highway Research Program, National Research Council, 1994, 301 pp. 28 Traylor, M.L., “Efforts to Eliminate D-Cracking in Illinois,” Transportation Research Record, No. 853, 1982, pp. 9-14. 29 Marks, V.J. and Dubberke, W., “Durability of Concrete and the Iowa Pore Index Test,” Transportation Research Record, No. 853, 1982, pp. 25-31.

39 Guide Specification for High-Performance Concrete for Bridges

C5.3 Water result. AASHTO M 157 (ASTM C 1602) also provides Refer to PCA EB001, Design and Control of Concrete guidance on the acceptability and testing of water for Mixtures, for a complete discussion of water for use in use in concrete. concrete. In general, water suitable for drinking and with no perceptible taste or odor is suitable for making C5.4 Chemical Admixtures concrete. Some non-potable waters including recycled It is advisable to purchase all of the chemical admixtures wash waters, are also acceptable for use in concrete but to be used in the concrete from a single manufacturer. must be tested to verify that no harmful effects will Certain chemical admixtures are incompatible with one another, or with certain cementitious materials. Generally, manufacturers test their own admixtures in combinations with one another using the available cementitious materials and can advise the user of potential interactions.

Early stiffening may result when water-reducing admixtures containing lignosulfonate and/or triethanolamine (TEA) are used in combination with some cements and Class C fly ashes, particularly in hot weather. Trial batches should be conducted at working temperatures to assess the likelihood of incompatibility. Tests conducted on the trial batches should include monitoring slump loss, time of set, and the temperature of the mixture with time.

Figure C5.3-1. Water that is safe to drink is safe to use in concrete. ACI 201.2 reports that if chloride ions in an admixture (IMG12312) are less than 0.01% by mass of cementitious material, such contribution represents an insignificant amount and may be considered innocuous.

Figure C5.3-2. Microwave Water Content Test (AASHTO T 318). Freshly mixed concrete wrapped in a fiberglass cloth in a heat-resistant glass tray (Pyrex) is dried in a microwave oven using a minimum of three drying intervals. The water content of the test specimen is calculated based on loss in mass of the test specimen. The w/c ratio can then be determined by dividing the amount of water from the microwave tests by the amount of cement indicated on the batch ticket. (left: IMG17613, right: IMG17614).

40 Guide Specification for High-Performance Concrete for Bridges

C6.0 Submission and Design Requirements C6.1 Concrete Mixture Proportioning In times of high demand for concrete-making materials, it is recommended that alternate mix designs using alternate materials be submitted for approval simultaneously. If a material then becomes unavailable during the course of a job, the concrete producer may substitute another material and the appropriate mix design without delay. The concrete producer must inform the purchaser when substitutions are to be made, even when the materials Figure C5.4-1. Liquid admixtures, from left to right: antiwashout admixture, shrinkage reducer, water reducer, foaming agent, corrosion and mix designs already have been approved. inhibitor, and air-entraining admixture. (IMG12188) For mixture proportioning, refer to “Design and Con- trol31,” or ACI 211.1 for normal density concrete, ACI 211.2 for lightweight concrete, and ACI 211.4 for The surface tension of the water in partially filled pores in high-strength concrete containing fly ash. Recommen- concrete pulls inward on the walls of the pores, resulting dations for proportioning high-strength concrete also are in shrinkage of the concrete. Shrinkage-reducing admix- covered in Chapter 3 of ACI 363R. tures reduce the surface tension of the pore water, reducing both the shrinkage and the susceptibility to cracking under restrained conditions. Shrinkage-reducing admixtures are used conventionally in applications where a notable reduction in drying shrinkage is desired and also may benefit concrete mixtures susceptible to autogenous shrinkage30. Shrinkage-reducing admixtures may affect strength, resistance to chloride ion ingress, freeze/ thaw durability, modulus of elasticity, creep, and long- term shrinkage. They should never be used in lieu of proper curing.

Hydration-stabilizing admixtures may be useful in situations where a controlled extension of set time is desired, such as extended hauls and during large continuous placements. Unlike conventional set retarding admixtures, hydration-stabilizing admixtures are formulated to Figure C6.1-1. Testing concrete mixes in the lab is often more provide extended set time control. Depending on the convenient and economical than having to batch large quantities at a dosage used, set time extensions can range from a few concrete plant. It is important to recognize that project conditions are hours to over a day. vastly different than the controlled environment of a laboratory. Production variability and testing variability need to be considered Corrosion inhibiting admixtures may be added to concrete and understood when lab tests results are interpreted. (IMG16954) to reduce the risk of corrosion of steel embedded in concrete. These products must be used in conjunction with and not in lieu of good concrete materials and practice.

30 Tazawa, Ei-ichi, Ed., “Autogenous Shrinkage of Concrete,” Proceedings of the International Workshop Organized by the Japan Concrete Institute, E&FN Spon, 1999, p. 14. 31 Kosmatka, Steven H.; Kerkhoff, Beatrix; and Panarese, William C., Design and Control of Concrete Mixtures, EB001, Portland Cement Association, 2002, 372 pages.

41 Guide Specification for High-Performance Concrete for Bridges

Note that the end product of the ACI mix proportioning The Engineer and Contractor should work together to methods is not a prescriptive “recipe” for a concrete mix select the combination of crack control measures that design, but a starting point for laboratory trial batches. best meets the requirements of the project at a Such characteristics as the packing efficiency and water reasonable cost. demand of the aggregates will affect the actual quantity of cement paste required for the desired workability. The Crack control measures related to the selection of dosages of water reducing and air-entraining admixtures constituent ingredients and proportioning of the concrete also must be determined by trial batches using the mixture include: manufacturer’s recommended dosages as the starting point. In addition, all properties of the fresh and 1. Selection of a suitable cement. hardened concrete determined by the Engineer to be important to the project must be tested to ensure that 2. Replacement of some of the cement with a low- the mix design meets the project requirements. calcium (Class F) fly ash, or use a blended cement containing Class F fly ash. C6.2 Concrete Production Facility Certification 3. Minimization of the water content. This may be done by employing a water reducer and/or by selecting a The NRMCA truck and plant certification programs favorable aggregate size and grading. The use of a follow a checklist inspection process for components and compatible fly ash also may reduce water demand. systems in concrete plants and verify that they conform to the requirements of AASHTO M 157 (ASTM C 94) and 4. Selection of an aggregate with a low coefficient of pertinent standards of concrete production equipment. thermal expansion and a rough surface texture. Maximize the aggregate content by specifying the C6.3 Concrete Materials largest possible maximum size and a favorable When producing high-performance concrete, it is advis- particle size grading. able for the concrete producer to retain traceable grab samples of the constituent concrete-making materials 5. Use of a shrinkage-reducing admixture, possibly in from each day’s production. The retained samples allow combination with carbon or steel fibers. for later investigation of any problems with the concrete. A 5-gallon (20 liter) pail of each aggregate and cementitious material, representative of A J each day’s production with that ingredient, A is sufficient for this purpose. Samples B I should be retained for six months. I E C6.4 Temperature Control K C Methods Shear cracks F Recommended practices for controlling the r placement temperature and in-place icke of k temperature of concrete placed during hot H Top B weather and cold weather are detailed in G H B ACI 305R and 306R, respectively, and in PCI “Bad,” i.e. ineffective, joint Tension bending MNL-116 and TM-103. H L cracks Cracks at I kicker joints C6.5 Crack Control Methods D M Plus Cracks may be caused by any combination rust of stresses arising from restraint of autoge- stains nous, plastic, or drying shrinkage; thermal Figure C6.5-1. An illustration of nonstructural cracks that may occur in a hypothetical gradients; imposed loads; and stress concrete structure (Concrete Society, 1982). concentrations such that the tensile stress A to C—plastic settlement, D to F—plastic shrinkage, G to H—thermal effects, I—drying exceeds the tensile strength of the concrete. shrinkage, J to K—crazing, L to M—reinforcement corrosion, N—alkali silica reaction.

42 Guide Specification for High-Performance Concrete for Bridges

6. Reducing the modulus of elasticity (stiffness) by the 1. Minimization of strains likely to occur in structural entrainment of 4% to 6% air in the concrete even if elements. For example, to minimize cracking in a it is not necessary for frost resistance. bridge deck it may be necessary to limit the deflection of the supporting girders. 7. Use of an aggregate with an absorption of less than 1%, or ensuring that the aggregate moisture 2. Limiting the maximum dimensions of any structural condition is always at or above saturated surface dry. element by providing construction joints.

Crack control measures related to workmanship include: 3. Not specifying a higher strength than necessary, or if possible, specifying a 56- or 90-day strength rather 1. Control of the placement temperature. The concrete than an earlier age strength. should not be much cooler than the ambient temperature, however. In winter, it may be advantageous for 4. Minimization of the restraint to which the concrete is the concrete to be somewhat warmer than the subjected. ambient temperature. Depending on the importance of controlling cracking, a detailed analysis of thermal 5. Use of reinforcing steel to develop a greater number stresses may be necessary. of small cracks rather than a few large cracks.

2. Use of established procedures for hot-weather and 6. Use of a large number of small-diameter reinforcing cold-weather concreting to control concrete quality. bars at close spacing rather than a few large-diameter bars. (Note that the bar spacing must permit ade- 3. Appropriate construction management to have suffi- quate consolidation of the concrete.) cient personnel at the site to place, consolidate, and finish the concrete promptly. In evaluating the literature on the relationship between corrosion of uncoated reinforcement and cracks perpen- 4. Provision of fog sprays and windbreaks as necessary dicular to it, Oesterle32 concluded that for crack widths to prevent the surface of the concrete from drying. less than 0.016 in. (0.4 mm), crack width was of minor importance. The quality of the concrete and the depth of 5. Curing the concrete as soon as possible. cover over the reinforcement are the primary factors determining the service life of cracked concrete. He 6. Control of the temperature after placement. Allowing recommended limiting crack widths to a maximum of controlled evaporation of water from absorptive blan- 0.016 in. (0.4 mm) for corrosion protection. kets on the surface is an effective means of both cooling and moist curing. Mailvaganam et. al.33 recommended the following limits: 7. Adherence to established procedures for good con- • Maximum of 0.004 in. (0.1 mm) for the most severe creting practice. Consult the documents of American exposure (industrial or marine environment where Concrete Institute Committees 201, 207, 224, 232, watertightness is essential) 233, 234, 304, 305, 306, 308, 309, 345, and/or 363, • Maximum of 0.008 in. (0.2 mm) for normal exterior and PCI MNL–116 as appropriate. exposures or interior exposures of structural members in humid or aggressive atmosphere Crack control measures related to structural design and detailing include: • Maximum of 0.012 in. (0.3 mm) for internal and protected members

32 Oesterle, R.G., The Role of Concrete Cover in Crack Control Criteria and Corrosion Protection, Portland Cement Association R.& D. Serial No. 2054, 1997. 33 Mailvaganam, Noel P.; Grattan-Bellew, P.E.; and Perinca, Gerry, “Deterioration of Concrete: Symptoms, Causes, and Investigation,” National Research Council, Canada, Institute for Research in Construction, Ottawa, Canada, 2000.

43 Guide Specification for High-Performance Concrete for Bridges

C6.6 Curing The objective of curing is to maintain moisture and tem- Curing methods, materials and monitoring procedures perature conditions for sufficient time to allow for the are detailed in ACI 308R and in FHWA FP-03 for cast-in- hydration of cementitious materials and pozzolans. Good place concrete and PCI MNL-116 for precast concrete. curing is essential for the concrete to develop the desired Where it is practical, moist curing is preferable to the durability and strength, and to minimize cracking. De- application of a curing compound. For precast concrete, pending on the properties desired, HPC may have lower use curing described in PCI MNL-116. water-cementitious materials ratio, higher cementitious

Figure C6.6-1. Curing methods that maintain the presence of mixing water in the concrete during the early hardening period include ponding or immersion, spraying or fogging (top left photo), and saturated wet coverings (top right photo). Methods that reduce the loss of mixing water from the surface of the concrete include covering the concrete with impervious paper or plastic sheets, or by applying membrane-forming curing compounds (bottom photos). Curing often involves a series of different procedures used at a particular time as the concrete ages. For example, fog spraying or plastic covered wet burlap can precede application of a curing compound. (IMG16978, IMG16979, IMG16981, IMG16980)

44 Guide Specification for High-Performance Concrete for Bridges

materials content, and/or reduced bleeding as compared Temperature-matched curing uses data from the thermo- with conventional concretes. The higher the cement couples to control the curing temperature of companion content, the greater attention should be given to curing cylinders. The compressive strength (or other property) of methods to control the development of internal tempera- the cylinders is determined directly and closely matches ture differentials which could lead to cracking. In the that of the concrete in the structure at the same time. case of aggressively evaporative environments, i.e. low Temperature-matched curing is thus simpler to imple- humidity and/or windy conditions, use of fogging, sun- ment than the maturity method and provides more direct shades, windscreens, or enclosures may be necessary to information about the current properties of the in-situ prevent excessive surface drying. Curing must be initiated concrete, but does not predict properties. before the concrete starts to dry. If water curing is employed, it should be done on a con- C7.0 Quality Management tinuous basis throughout the specified curing period. The guide specification has been based on the presump- Intermittent water curing that allows concrete to under- tion that a given concrete mixture will be pre-qualified by go cycles of wetting and drying can be more detrimental specification and testing appropriate for the given ele- than no curing at all. ment and environment. Quality assurance and control are If steam curing is employed, care should be taken to pre- then based on confirming that every load of concrete vent the concrete temperature exceeding the tempera- used at the site is comparable to the pre-qualified mixture above which the risk of delayed ettringite formation ture. This means that it is not necessarily required to test may occur in mixtures containing materials prone to the every property of every load, but to confirm that the problem. In general, 158°F (70°C) is accepted as a materials and mix proportions are the same as those in reasonable upper limit. Higher temperatures may be ac- the pre-qualified mix, and that selected indicators of vari- ceptable for certain materials if proven by field perfor- ability (such as air content and consistency) remain within mance or test. suitable bounds.

Both maturity and temperature-matched curing are excel- C7.1 Quality Assurance lent methods of assessing the development of strength Refer to ACI 121R, PCI MNL-116, AASHTO Guide to or other properties of the concrete at early ages. Deci- Quality Control/Quality Assurance, and NRMCA Publi- sions such as when to re–move forms, release cation 190 for more detail on quality assurance systems. prestressing, or post-tension can be made more reliably with information from either of these methods. Both C7.2 Quality Control methods require the use of thermocouples to measure Recommended practices related to quality control and the temperature history of the concrete. testing of high-strength concrete are detailed in ACI 363.2, “Guide to Quality Control and Testing of High- The maturity method predicts the in-situ strength (or Strength Concrete,” PCI MNL-116, NRMCA Quality other properties) of the concrete at any time based on Control Manual, and NRMCA Publication 190. data developed from the trial batches. Thus it requires an investment in testing the development of the desired In principle, sufficient testing is required to ensure that properties using trial batches subjected to a range of the requirements of the specification are being complied curing conditions representing those anticipated on site. with, and that a uniform product is being produced. The ASTM C 1074 generates a maturity index based on the tests should be related to the parameters deemed impor- temperature history. tant in the specification. Some tests may be conducted at pre-qualification stage to assure that the mix design The maturity method normally is used to assess the cur- provides an adequate concrete, while production accep- rent strength of the concrete; however, it also can be tance testing may be done to demonstrate that the con- used to model different hypothetical situations, such as crete being delivered from batch to batch is equivalent to the length of time formwork should remain in place or the qualified mixture. whether it would be effective to use insulated forms or heated enclosures during cool weather to accelerate the construction schedule.

45 Guide Specification for High-Performance Concrete for Bridges

C8.0 Production of Concrete silica fume guarantees uniform mixing. The use of pulpable bags of silica fume is not advisable, as it may be C8.1 General difficult to achieve adequate mixing. The specifier may wish to consult the silica fume supplier for recom- C8.2 Equipment mendations. In situations where discharge of the concrete may not be C8.5 Temperature Control completed within the allowable time limitations, such as extended hauls, hydration-stabilizing admixtures may be Temperature of concrete is important for the development beneficial. Hydration-stabilizing admixtures are discussed of properties related to strength and durability. So long as in Section C5.4. the concrete is protected from freezing, low temperatures result in the development of favorable properties, but at a C8.3 Measurement of Materials significantly slower rate. Early-age freezing of concrete may disrupt the paste microstructure and permanently Consult the admixture manufacturer’s literature for guid- damage the concrete. Elevated temperatures result in ance as to the order in which admixtures should be accelerated setting and high early strengths but reduced added to the concrete, as this will affect their perfor- ultimate strengths, as well as higher permeability and mance. In general, admixtures should be introduced greater potential for delayed ettringite formation. The separately to the batch. exact temperature at which the concrete becomes vul- Materials quantities in freshly mixed or hardened con- nerable to delayed ettringite formation varies with the crete can be approximated using a number of tech- cementitious material(s) employed. niques. The water content of fresh concrete can be In general, 158°F (70°C) is accepted as a reasonable determined using the Microwave test (AASHTO T 318,) upper limit. Higher temperatures may be acceptable for except that allowance has to be made for the moisture certain materials if proven by field performance or test. state of the aggregate at the time of mixing. Cement The maximum temperature of 158°F (70°C) is specified content may be estimated using ASTM C 1084 for for two reasons: systems that do not contain supplementary cementitious 1. Delayed ettringite formation is possible under some materials. Monitoring unit weight will provide a means of circumstances when the temperature exceeds this flagging changes in mixture proportions. value. C8.4 Mixing 2. The higher the curing temperature, the more perme- It is essential to ensure thorough mixing, both for uni- able the concrete. form distribution of the concrete ingredients throughout Appropriate use of supplementary cementitious materials the batch and to entrain an adequate air-void system. will reduce or eliminate the possibility of delayed However, overmixing may remove entrained air from the ettringite formation34. concrete. In addition, with some synthetic air-entraining admixtures, retempering and extended mixing can result Some concrete ingredients and mix proportions are in excessive air and/or clustering of air voids. Trial batches better suited than others for extreme weather conditions. and mockups should be used to verify that the ingre- In hot weather, supplementary cementitious materials dients and procedures used would result in satisfactory such as Class F fly ash and slag cement, which generate air-void systems in the concrete as placed. less heat of hydration than cement, help keep the heat development of the concrete in the appropriate range, If silica fume is used, particular attention must be paid to thus minimizing the likelihood of thermal cracking. They the batching sequence and mixing procedure to ensure also can make the concrete less susceptible to premature uniform mixing. The use of a blended cement containing stiffening.

34 Miller, F.M., and Conway, T., “Use of Ground Granulated Blast Furnace Slag for Reduction of Expansion Due to Delayed Ettringite Formation,” Cement, Concrete and Aggregates, Vol. 25, Issue. 2, 2003, pp. 59-68.

46 Guide Specification for High-Performance Concrete for Bridges

C8.5.1 Cold Weather The primary concerns relating to cold weather are slow setting and slow strength gain, permanent damage to the concrete due to early freezing, and excessive thermal gradients that may lead to cracking.

When concrete is to be placed in cold weather, or at a time of year when cold weather is likely, plans to maintain the concrete at the appropriate temperature should be made well before the temperature is expected to drop below freezing.

Concrete mix designs developed for placement at cooler temperatures normally have somewhat higher cement contents than those for hot weather. The use of slag cement and fly ash may need to be reduced or elimi- Figure C8.5.1-1. Concrete being covered with a tarpaulin to retain heat nated unless they are required to control expansions due of hydration. (IMG15215) to alkali-silica reaction or to increase the resistance to sulfate attack or to reduce permeability. In that case, the total cementitious materials content may need to be freezing for the remainder of the curing period. If the increased, or Type III or Type HE cement may be used concrete is to be heated, it should be by a method that instead of Type I/II. The required dosage of air-entraining does not expose the concrete to CO2 gas. Note that admixture will be lower than at normal temperatures. corners and edges are the most vulnerable to freezing. The longer setting time of concrete in cold weather Concrete damaged by pre-mature freezing must be increases the window of vulnerability to plastic shrinkage completely removed and replaced. cracking. If the concrete is much warmer than the Note that in colder temperatures, concrete gains strength ambient air or the wind is blowing, the local reduction in more slowly. This effect is more pronounced for concrete relative humidity also can contribute to plastic shrinkage containing supplementary cementitious materials. Before cracking. Concrete surfaces must be protected from removing formwork or post-tensioning structural ele- drying with windbreaks, application of curing compound, ments, the adequacy of the in-place compressive etc. An accelerating admixture conforming to AASHTO M strength of the concrete must be verified by the maturity 194 (ASTM C 494) Type C or E may be used provided its method, temperature-matched curing, nondestructive performance previously has been verified by trial batch. testing, or tests of cores. Use of admixtures containing chlorides is not recom- Guidance and further details on cold weather concreting mended and in prestressed or post-tensioned concrete is practices are given in ACI 306R and PCI MNL-116. strictly prohibited.

Ideally, concrete should not be placed when the tempera- C8.5.2 Hot Weather tures of the air at the site or the surfaces on which the The primary concerns relating to hot-weather concreting concrete is to be placed are less than 40°F (5°C). If include increased water demand, premature stiffening, circumstances require that concrete be placed at these loss of workability, increased rate of setting, loss of temperatures, special provisions are required as detailed entrained air, plastic shrinkage cracking, decreased later- in ACI 306R and PCI MNL-116. Covering and/or other age strength, excessive hydration temperatures, and means of protecting the concrete should be available on excessive thermal gradients leading to cracking. High site before starting placement. The concrete temperature performance concrete may experience little or no should be maintained at 50°F (10°C) or above for at least bleeding; thus it is particularly sensitive to plastic 72 hours after placement and at a temperature above shrinkage cracking.

47 Guide Specification for High-Performance Concrete for Bridges

The concrete mix design used for hot weather should have been previously verified as appropriate using trial batches mixed and cast at temperatures representative of typical hot weather conditions at the site. The use of slag cement, Class F fly ash, and/or natural pozzolans in substitution for part of the cement is recommended. All of these materials hydrate more slowly and generate lower heats of hydration than cement, thus reducing problems with slump loss, premature stiffening, and thermal cracking. Class C fly ashes with high contents of Al2O3 may contribute to premature stiffening.

Reductions in air contents due to hot weather can be corrected by increasing the dosage of air-entraining Figure C8.5.2-1. Liquid nitrogen added directly into a truck mixer to admixture and/or by retempering with water-reducing reduce the concrete temperature. (IMG12357) admixture or water to restore the slump. Do not exceed the maximum allowable water-cementitious materials ratio or manufacturer’s maximum recommended dosage for any of the admixtures. Calcium sulfate in the form of gypsum and anhydrite is added to cement to control the hydration of aluminates, Retarding admixtures may be used if their performance preventing early stiffening. Elevated temperatures accel- previously has been verified by trial batches. erate the dissolution of the aluminates and retard the dissolution of the sulfates. Class C fly ashes with high Thermal cracking may be prevented by ensuring that the alumina contents can be problematic in hot weather if temperature of concrete at the time of placement is as they contribute more aluminates than soluble sulfates to low as practical, and in no case should it exceed 90°F the concrete. The use of some water-reducing admixtures (32°C) except in precast concrete plants that have also can contribute to early stiffening. This effect is more demonstrated successful use of a maximum temperature pronounced in hot weather because of the increased of 95°F (35°C). When possible, store aggregates out of water demand of the concrete (thus the tendency to use direct sunlight. Aggregates also may be cooled and higher dosages of water-reducing admixture).

Figure C8.5.2-2. Mass concrete footing where the insulation was removed much too soon and a large thermal gradient developed through the concrete by thermally shocking the surface. The footing was approximately 5 ft (1.5 m) thick, and the insulation was removed after ~2 days. The concrete cracked shortly thereafter. (left: IMG17801, right: IMG17802)

48 Guide Specification for High-Performance Concrete for Bridges

moistened by sprinkling with water. If possible, avoid the C8.5.3 Control of Temperatures use of hot cement or fly ash. Mixing water may be Traditionally, mass concrete members were considered to chilled, or chipped ice (batched by mass) may be used in be those with dimensions of 3 ft. (1 m) or more. How- substitution for some of the water. Be sure that all of the ever, high performance concrete may be more suscep- ice melts during mixing. Mixing and transporting equip- tible to cracking due to its higher cementitious materials ment may be painted white or a light color to minimize content and/or increased modulus of elasticity. Thus the heat absorbed from the sun. Depending on the heat special precautions may be required even for thinner HPC characteristics of the concrete, placements may be sched- members to minimize cracking. uled for late afternoon or nighttime to reduce thermal gradients. Delays in placement should be avoided. The The primary objective with mass concrete is to control use of a white curing compound will help reflect the the temperature gradient between the internal tempera- sun’s heat. ture and the surface. This can be accomplished by the following measures: Plastic shrinkage cracking results from loss of moisture 1. Minimizing the heat of hydration by appropriate from concrete before it has set. Aggregates should be selection of cementitious materials and limitation of batched as close to a saturated condition as possible to the cement content. Select the largest practicable avoid absorbing mix water. The concrete should be maximum size of aggregate and use supplementary protected from loss of moisture during mixing and place- cementitious materials known to reduce the heat. ment. Protection measures may include fog spraying and shelter from wind. Absorbent forms should be dampened 2. Minimizing the placement temperature of the con- before placement. The concrete should be placed and crete, for example by cooling the individual ingre- finished as rapidly as possible and curing compound (if dients, using ice for part of the mixing water, and/or used) applied as soon as possible. If there is any delay in injecting liquid nitrogen into the mixer. applying the curing compound, use a fog spray to keep 3. Cooling the concrete after placement by use of the surface from drying out. When the rate of evap- embedded cooling coils or pipes. oration is predicted from Figure C8.5.2-3 to be above 0.1 lb/ft2/hr (0.5 kg/m2/hr), provide wind screens and 4. Managing the construction procedures and sched- fog spraying as appropriate or stop placing concrete. uling to protect the concrete from excessive tempera- Note that high performance concrete is particularly ture differentials. For example, concreting may take vulnerable to plastic shrinkage cracking because it has place at night to prevent solar radiation from heating little or no bleeding. Take extra precautions to prevent the surface, or the surface may be insulated to mini- evaporation when placing silica fume concrete in hot mize the temperature difference between the surface weather. If plastic shrinkage cracking is observed, the and the interior. Contractor should provide wind screens and more fog spraying as needed. If these measures are not effective, Consult the publications of ACI 207.1R, 207.2R, and operations should stop until weather conditions improve.35 207.4R for further information and recommended practices. Guidance and further details on hot-weather concreting practices are given in ACI 305R and PCI MNL-116.

35 ACI 224R, Control of Cracking in Concrete Structures.

49 Guide Specification for High-Performance Concrete for Bridges

Relative humidity, percent Concrete temperature, °F 100 100

80 90

60 80

40 70

60 20 50 40 40 60 80 100 Air temperature, °F Wind velocity, mph

0.8 )

To use this chart: r h / t 2 f ( 0.6 25 b

1. Enter with air tempera- l ,

ture, move up to relative n o i

t 20

humidity a r o

2. Move right to concrete p 0.4 a 15 v

temperature e f

3. Move down to wind o e

t 10

velocity a 4. Move left; read approx. R 0.2 rate of evaporation 5 2 0 0

Figure C8.5.2-3. Effect of concrete and air temperatures, relative humidity, and wind velocity on rate of evaporation of surface moisture from concrete. Wind speed is the average horizontal air or wind speed in mph (km/h) measured at 20 in. (500 mm) above the evaporating surface. Air temperature and relative humidity should be measured at a level approximately 4 to 6 ft (1.2 to 1.8 m) above the evaporating surface and on the windward side shielded from the sun’s rays (Menzel 1954)36.

C8.6 Trial Batches and Mockups correlate early-age or accelerated-cure strengths with the Trial batches are essential to verify the performance char- corresponding specified design strength. acteristics of the concrete. Laboratory trial batches can be If a maturity method is to be used to monitor the used to calibrate field quality control measurements, for strength or other properties at early ages, the necessary example slump retention and the volume of air corre- data should be developed using trial batches. sponding with a satisfactory air-void system in the hardened concrete. Trial batches or mockups can be used to If the job is scheduled for a time of year when hot or cold weather is anticipated, trial batches should be cured

36 Menzel, Carl A., “Causes and Prevention of Crack Development in Plastic Concrete,” Proceedings of the Portland Cement Association, 1954, pp. 130 to 136.

50 Guide Specification for High-Performance Concrete for Bridges

at the anticipated job temperatures in addition to a stan- the addition of water at the site and permit the addition dard curing temperature of 23°C (73°F). The strength of a water reducing or high-range water-reducing admix- gain characteristics and effects on the development of ture at the site to achieve the required slump. the other specified properties could be determined.

Trial batches and mockups always should use concrete- making materials representative of those to be used through the course of the work. If material is to be supplied in bulk form, bagged materials should not be used in the trial batches or mockups.

Because of the time required to conduct trial batches and perform the required testing, it is advisable to conduct trial batches on a suite of concrete mix designs using the various materials under consideration for use. Then if substitution of a material is necessary during the course of the job, mix design already has been verified and the substitution can be made without delay.

Field trial batches and mockups verify that the batching, mixing, transport, placement, and finishing techniques to be used in the field with full-scale batches will produce satisfactory concrete. Pay special attention to any performance characteristics specified above Grade1. For example, if resistance to freezing and thawing and/or deicer scaling is specified, the air-void system of the concrete as placed is critical. Mixing, pumping (if used), consolidation, and finishing procedures all affect the air- void system. Cores should be taken from the mockup and examined according to ASTM C 457 to ensure that Figure C8.7-1. Admixture being added to concrete on-site. (IMG17641) the air-void spacing factor of the concrete near the top surface is acceptably low.

Permission may be granted to forgo some trial batch C8.8 Delivery Tickets testing if the supplier has supplied a similar material within the last 12 months. A shorter period may be Delivery tickets are an important form of quality selected, depending on the local conditions of material monitoring, because when things go wrong the tickets availability and variability, construction practices, and are the first source of information on what went into the contractor turnover. batch, and where in the structure the batch went. Such information can significantly reduce the amount of effort C8.7 Site Addition of Materials required in some forensic investigations. For high-performance concrete, the addition of water at the site should be avoided, particularly when high strengths or low chloride penetration values are specified. Late addition of water will compromise the microstructure and ultimate performance of the concrete, even such addition is to replace water apparently lost through evaporation or aggregate absorption. It is best to prohibit

51 Guide Specification for High-Performance Concrete for Bridges

Index

A Calcium sulfate, 30, 48 Abrasion, 2, 3, 4, 7, 17, 18, 19, 20, 21 Cement content, 19, 45, 46, 49 Resistance, 4, 7, 17, 18, 20, 21 Cement paste, 24, 36, 42 Admixtures, 2, 3, 4, 10, 15, 16, 19, 26, 28, 30, 34, 40, Cementitious materials, 1, 4, 5, 6, 7, 8, 10, 13, 14, 15, 41, 42, 46, 47, 48 16, 19, 22, 23, 27, 29, 30, 33, 34, 35, 36, 37, 38, Aggregates, 2, 3, 7, 8, 9, 10, 13, 14, 16, 18, 19, 21, 24, 40, 44, 46, 47, 48, 49 26, 33, 34, 35, 36, 37, 38, 42, 46, 48, 49 Chemical admixtures, 2, 4, 10, 19, 26, 30, 40 Agitating equipment, 13 Chloride(s), 10, 21, 47 Air content, 2, 3, 10, 15, 19, 25, 26, 27, 45 Chloride ion penetration, 1, 3, 4, 7, 17, 18, 21, 22 Air void analyzer, 19, 25 Chloride penetration, 2, 19, 20, 22, 51 Air-entraining admixture(s), 2, 3, 15, 36, 41, 42, 46, 47, Clay(s), 5, 6, 9, 22, 36, 38, 56 48 Coarse, 2, 3, 7, 8, 9, 23, 24, 26, 36, 38, 39 Air-void(s), 3, 25, 27, 46, 50, 51 Cold, 5, 10, 11, 14, 42, 43, 47, 50 Alkali carbonate reaction, 8, 9, 19, 38 Cold weather, 5, 10, 11, 14, 42, 47, 50 Alkali silica reaction, 3, 4, 8, 9, 17-20, 34, 35, 37-38, Composition, 23, 38 42, 47 Compressive strength, 1, 2, 3, 7, 11, 16, 17, 18, 19, 20, Aluminates, 48 22, 23, 24, 25, 45, 47 Ambient temperature, 30, 43 Consistency, 1, 6, 7, 8, 17, 18, 19, 32, 33, 45 Anhydrite, 48 Consolidation, 5, 6, 15, 18, 25, 33, 43, 51 Autogenous, 2, 28, 29, 39, 41, 42 Construction joints, 21, 43 Autogenous shrinkage, 27, 28, 29, 41 Construction management, 43 B Corrosion inhibiting admixtures, 41 Bleeding, 14, 27, 28, 36, 45, 47, 49 Corrosion inhibitors, 10 Blended cement(s), 5, 8, 14, 38, 42, 46 Cracking, 1, 2, 3, 4, 5, 8, 9, 10, 14, 18, 19, 23, 24, 27, 28, 29, 35, 36, 38, 39, 41, 43, 44, 45, 46, 47, 48, Blended hydraulic cement, 2, 38 49 Bridge deck, 1, 5, 23, 43 Creep, 1, 4, 5, 6, 7, 17, 18, 19, 20, 22, 23, 25, 30, 36, Bull floating, 11 41 Burlap, 11, 29, 30, 44 Curing, 2, 3, 5, 6, 7, 10, 11, 14, 15, 17, 21, 22, 23, 25, 27, 28, 29, 30, 38, 41, 43, 44, 45, 46, 47, 49, 51 C Cylindrical concrete specimens, 2, 3 Calcined clay, 5, 6, 22, 36, 38

53 Guide Specification for High-Performance Concrete for Bridges

D H D-cracking, 8, 9, 10, 19, 38, 39 Hard-troweling, 38 Deflections, 1, 18, 22, 23, 24 Heat development, 36, 46 Deicing salts, 8, 18, 21, 23, 27 Heat of hydration, 36, 46, 47, 49 Diffusivity, 22 High-strength concrete, 1, 2, 5, 21, 23, 24, 28, 41, 45 Drying shrinkage, 2, 7, 27, 28, 30, 36, 39, 41, 42 Hot, 5, 6, 10, 11, 13, 14, 29, 38, 40, 42, 43, 46, 47, 48, Durability, 1, 2, 6, 7, 8, 10, 17, 18, 20, 22, 25, 29, 37, 49, 50 39, 41, 44, 46 Hot weather, 5, 6, 13, 14, 40, 42, 46, 47, 48, 49 Hydration, 6, 23, 27, 29, 36, 41, 44, 46, 47, 48, 49 E Early stiffening, 8, 40, 48 I Early-age strength, 22 Ice floes, 18, 21 Elasticity, 1, 4, 7, 17, 18, 19, 20, 22, 24, 25, 36, 41, 43, Innocuous, 9, 37, 40 49 Iowa Pore Index Test, 10, 19, 39 Ettringite, 45, 46 J Evaporation, 14, 28, 29, 43, 49, 50, 51 J-ring, 19, 32 Expansion, 3, 9, 10, 20, 34, 35, 37, 38, 39, 42, 46 Jobsite, 15 Exposure, 7, 8, 18, 21, 26, 31, 35, 43 L F Lignosulfonate, 40 Federal Highway Administration, 4 Liquid nitrogen, 48, 49 FHWA, 4, 11, 12, 17, 19, 20, 21, 22, 23, 44 Low permeability, 28 Fine, 2, 3, 8, 9, 26, 29, 36 Low-alkali cement, 35, 37 Fineness, 23, 36 Finishing, 2, 11, 14, 15, 21, 27, 29, 38, 51 M Floating debris, 18, 21 Mailvaganam, 43 Fly ash, 2, 4, 5, 6, 8, 11, 22, 30, 36, 38, 41, 42, 46, 47, Masonry construction, 5, 6 48, 49 Microstructure, 22, 46, 51 Fog spray(s), 14, 29, 30, 43, 44, 49 Microwave, 3, 40, 46 Formwork, 6, 29, 30, 45, 47 Mixing, 2, 4, 5, 10, 12, 13, 14, 15, 16, 26, 44, 46, 49, Freeze thaw, 7, 18, 19, 25 51 Freeze/thaw durability, 7, 18, 25 Mixture, 2, 9, 10, 16, 23, 24, 25, 27, 28, 32, 40, 41, 42, Freezing, 3, 4, 9, 18, 25, 26, 38, 39, 46, 47, 51 45, 46 Fresh concrete, 25, 36, 38, 46 Modulus, 1, 4, 7, 17, 18, 19, 20, 22, 24, 25, 36, 41, 43, 49 G Modulus of elasticity, 1, 4, 7, 17, 18, 19, 20, 22, 24, 25, Grading, 8, 24, 33, 35, 36, 37, 42 36, 41, 43, 49 Gravimetric, 3 Moisture, 6, 14, 16, 23, 26, 27, 29, 30, 33, 43, 44, 46, Grooving, 11 49, 50 Groundwater, 18, 30 Mortar, 2, 3, 4, 5, 6, 9, 26, 27, 34, 35, 36 Grout, 2, 6 N Gypsum, 48 National Ready Mixed Concrete Association, 5, 10, 13 Non-agitating equipment, 13

54 Guide Specification for High-Performance Concrete for Bridges

Non-potable, 40 Silts, 36 NRMCA, 5, 10, 19, 42, 45 Slag, 2, 3, 4, 5, 6, 8, 11, 22, 30, 31, 36, 38, 46, 47, 48 Slump, 1, 2, 3, 6, 8, 10, 15, 19, 20, 26, 32, 33, 40, 48, P 50, 51 Paste content, 1, 28, 29, 39 Snowplows, 18, 21 Permeability, 22, 28, 46, 47 Sodium sulfate, 30 Petrographic, 3, 4, 8, 34, 37 Stiffness, 1, 23, 36, 43 Placement, 11, 13, 14, 15, 25, 29, 30, 32, 33, 36, 42, Stiffening, 8, 40, 46, 47, 48 43, 47, 48, 49, 51 Strength development, 36 Placing, 2, 5, 14, 15, 29, 49 Subgrade, 29 Plant certification, 10, 12, 13, 42 Sulfate attack, 8, 30, 31, 47 Plastic shrinkage, 14, 28, 29, 42, 47, 49 Sulfate resistance, 7, 17, 18, 19, 20, 30, 31 Popouts, 38 Supplementary cementitious material(s), 1, 5, 6, 8, 19, Pore index, 10, 19, 39 22, 23, 27, 36, 38, 46, 47, 49 Portland cement, 2, 3, 4, 5-6, 8, 9, 22, 29, 30-31, 34, Sustained load, 6, 23 36, 38, 41, 43, 50 Post-tension, 45 T Pozzolans, 3, 5, 8, 22, 31, 38, 44, 48 Tarpaulins, 11 Prestressed Concrete, 1, 5, 10, 11, 18, 21, 22, 23, 30 Temperature control, 10, 11, 14, 42, 46 Prestressing, 18, 45 Thawing, 3, 4, 9, 18, 25, 38, 39, 51 Preventive measures, 30 Thermal cracking, 1, 18, 36, 46, 48 Proportions, 5, 7, 10, 23, 28, 29, 45, 46 Thermal stresses, 10, 39, 43 Proportioning, 2, 10, 26, 41, 42 Transport, 13, 15, 18, 51 Pumping, 25, 51 Transporting, 2, 5, 49 Trial batch(es), 10, 15, 26, 33, 40, 42, 45, 46-48, 50, 51 R Triethanolamine (TEA), 40 Reactive, 9, 18, 22, 34, 37, 38 Truck traffic, 21 Ready-mixed concrete, 2, 3, 19 Reinforcing bars, 43 V Reinforcing steel, 4, 43 Volume, 4, 6, 12, 15, 16, 24, 25, 26, 29, 36, 39, 50

S W Salt scaling, 19 Washington Hydraulic Fracture Test, 9, 19, 39 Saturation, 25, 38 Water content, 3, 19, 40, 42, 46 Scaling resistance, 1, 4, 7, 17, 18, 20, 27 Water-cementitious materials ratio (w/cm), 6, 7, 15, 18, SCC, 6, 8, 19, 32, 33 22, 23, 27, 29, 30-31, 44, 48 Screeding, 11 Water-reducing admixture(s), 15, 32, 33, 40, 48, 51 Self-consolidating concrete (SCC), 1, 5, 6, 8, 32, 33 Windbreaks, 29, 43, 47 Setting time, 36, 47 Shale, 36, 38 Shrinkage, 2, 5, 7, 10, 14, 17, 18, 19, 20, 27, 28, 29, 30, 36, 39, 41, 42, 47, 49 Silica fume, 2, 4, 5, 6, 8, 11, 14, 22, 30, 36, 46, 49 Siliceous, 9

55 An organization of cement companies to improve and extend the uses of portland cement and concrete through market development, engineering, research, education and public affairs work. EB233