Economical and Crack-Free High-Performance Concrete for Pavement and Transportation Infrastructure Construction

Total Page:16

File Type:pdf, Size:1020Kb

Economical and Crack-Free High-Performance Concrete for Pavement and Transportation Infrastructure Construction Economical and Crack-Free High-Performance Concrete for Pavement and Transportation Infrastructure Construction Prepared by: Kamal H. Khayat, PhD, P.Eng. (principal investigator) Iman Mehdipour, PhD Candidate (student) Missouri University of Science and Technology Final Report Prepared for Missouri Department of Transportation May 2017 Project TR201503 Report cmr17-007 TECHNICAL REPORT DOCUMENTATION PAGE 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. cmr 17-007 4. Title and Subtitle 5. Report Date Economical and Crack-Free High-Performance Concrete for Pavement and June 30, 2016 Transportation Infrastructure Construction Published: May 2017 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Kamal H. Khayat, PhD, P.Eng. http://orcid.org/0000-0003-1431-0715 00047062 Iman Mehdipour, PhD Candidate http://orcid.org/0000-0002-6841-3907 9. Performing Organization Name and Address 10. Work Unit No. Center for Transportation Infrastructure and Safety/UTC program Missouri University of Science and Technology 11. Contract or Grant No. 220 Engineering Research Lab, Rolla, MO 65409 MoDOT project #TR2015-03 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Missouri Department of Transportation (SPR) Final Report (June 23, 2014-June 30, Construction and Materials Division 2016) P.O. Box 270, Jefferson City, MO 65102 14. Sponsoring Agency Code 15. Supplementary Notes Conducted in cooperation with the U.S. Department of Transportation, Federal Highway Administration. MoDOT research reports are available in the Innovation Library at http://www.modot.org/services/or/byDate.htm. This report is available at https://library.modot.mo.gov/RDT/reports/TR201503/cmr17-007.pdf 16. Abstract The main objective of this research is to develop and validate the behavior of a new class of environmentally friendly and cost- effective high-performance concrete (HPC) referred to herein as Eco-HPC. The proposed project aimed at developing two classes of Eco-HPC for the following applications: (i) HPC for pavement construction (Eco-Pave-Crete); and (ii) HPC for bridge infrastructure construction (Eco-Bridge-Crete). The binder contents for these construction materials were limited to 320 kg/m3 3 3 3 (540 lb/yd ) and 350 kg/m (590 lb/yd ), respectively, in order to reduce paste content, cost, CO2 emissions, and shrinkage. Both Eco-HPC types were optimized to develop high resistance to shrinkage cracking as well as to secure high durability. Given the relatively low binder content, the binder composition and aggregate proportion were optimized based on the packing density approach to reduce the paste required to the fill the voids among aggregate particles. The optimized concrete mixtures exhibited low autogenous and drying shrinkage given the low paste content and use of various shrinkage mitigating strategies. Such strategies included the use of CaO-based expansive agent (EX), saturated lightweight sand (LWS), as well as synthetic or recycled steel fibers. Proper substitution of cement by supplementary cementitious materials (SCMs) resulted in greater packing density of solid particles, lower water/superplasticizer demand, and improved rheological and hardened properties of cement-based materials. A statistical mix design method was proposed and was shown to be effective in optimizing the aggregate proportioning to achieve maximum packing density. The synergistic effect between EX with LWS resulted in lower autogenous and drying shrinkage. For a given fiber content, the use of steel fibers recovered from waste tires had twice the flexural toughness of similar mixture with synthetic fibers. The optimized Eco-HPC mixtures had lower drying shrinkage of 300 μstrain after 250 days. The risk of restrained shrinkage cracking was found to be low for the optimized concrete mixtures (no cracking even after 55 days of testing). The results of structural performance of large-scale reinforced concrete beams indicated that the optimized Eco-Bridge-Crete containing ternary combination of 35% fly ash and 20% slag replacements and recycled steel fibers developed significantly higher flexural toughness compared to the MoDOT reference mixture used for bridge infrastructure applications. 17. Key Words 18. Distribution Statement Bridge decks; Bridge members; Bridge piers; Cast in place No restrictions. This document is available through the structures; Concrete; Girders; High performance concrete; Paving. National Technical Information Service, Springfield, VA Crack-free; Early-age cracking; Eco-Crete; Packing density; 22161. Shrinkage mitigating strategies, Supplementary cementitious materials 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified. Unclassified. 218 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized M SSOURI Uni,iersit;r of L. c· l. .C ~ C 1 g)·' & ·.. l Economical and Crack-Free High-Performance Concrete for Pavement and Transportation Infrastructure Construction Project Number: TR2015-03 Final Report Kamal H. Khayat, PhD, P.Eng. Iman Mehdipour, PhD Candidate June 30, 2016 ABSTRACT The main objective of this research is to develop and validate the behavior of a new class of environmentally friendly and cost-effective high-performance concrete (HPC) referred to herein as Eco-HPC. The proposed project aimed at developing two classes of Eco-HPC for the following applications: (i) HPC for pavement construction (Eco-Pave-Crete); and (ii) HPC for bridge infrastructure construction (Eco-Bridge-Crete). The binder contents for these construction materials were limited to 320 kg/m3 (540 lb/yd3) and 350 kg/m3 (590 lb/yd3), respectively, in order to reduce paste content, cost, CO2 emissions, and shrinkage. Both Eco-HPC types were optimized to develop high resistance to shrinkage cracking as well as to secure high durability. Given the relatively low binder content, the binder composition and aggregate proportion were optimized based on the packing density approach to reduce the paste required to the fill the voids among aggregate particles. The optimized concrete mixtures exhibited low autogenous and drying shrinkage given the low paste content and use of various shrinkage mitigating strategies. Such strategies included the use of CaO-based expansive agent (EX), saturated lightweight sand (LWS), as well as synthetic or recycled steel fibers. Proper substitution of cement by supplementary cementitious materials (SCMs) resulted in greater packing density of solid particles, lower water/superplasticizer demand, and improved rheological and hardened properties of cement-based materials. A statistical mix design method was proposed and was shown to be effective in optimizing the aggregate proportioning to achieve maximum packing density. The synergistic effect between EX with LWS resulted in lower autogenous and drying shrinkage. For a given fiber content, the use of steel fibers recovered from waste tires had twice the flexural toughness of similar mixture with synthetic fibers. The optimized Eco-HPC mixtures had lower drying shrinkage of 300 μstrain after 250 days. The risk of restrained shrinkage cracking was found to be low for the optimized concrete mixtures (no cracking even after 55 days of testing). The results of structural performance of large-scale reinforced concrete beams indicated that the optimized Eco-Bridge-Crete containing ternary combination of 35% fly ash and 20% slag replacements and recycled steel fibers developed significantly higher flexural toughness compared to the MoDOT reference mixture used for bridge infrastructure applications. Keywords: Bridge; Crack-free concrete; Early-age cracking; Eco-Crete; Expansive admixture; Packing density; Pavement; Shrinkage, Supplementary cementitious materials. I ACKNOWLEDGEMENT The authors would like to acknowledge the many individuals and organizations that made this research project possible. First and foremost, the authors would like to acknowledge the financial support of Missouri Department of Transportation (MoDOT) as well as the RE-CAST (REsearch on Concrete Applications for Sustainable Transportation) Tier-1 University Transportation Center (UTC) at Missouri University of Science and Technology (Missouri S&T). The authors would also like to thank the companies that provided materials required for the successful completion of this project, including LafargeHolcim, BASF, Euclid Chemical, Buildex, and Capital Sand Company, as well as Granuband Macon. The cooperation and support from Abigayle Sherman and Gayle Spitzmiller of the Center for Infrastructure Engineering Studies (CIES) is greatly acknowledged, in particular the assistance of Dr. Soo-Duck Hwang, Lead Scientist, and Jason Cox, Senior Research Specialist is highly appreciated. Valuable technical support provided by technical staff of the Department of Civil, architectural, and Environmental Engineering at Missouri S&T is deeply appreciated, in particular Brian Smith, John Bullock, and Gary Abbott. II EXECUTIVE SUMMARY This research project was undertaken to develop a new class of environmentally friendly, cost- effective, and crack-free high-performance concrete (HPC) for use in pavement (Eco-Pave- Crete) and bridge infrastructure (Eco-Bridge-Crete) applications. The binder content of these novel materials were limited to 320 kg/m3 (540 lb/yd3) and 350 kg/m3 (590 lb/yd3), respectively, in order to reduce paste content, cost, CO2 emissions, and shrinkage. The rheological properties of the Eco-HPCs
Recommended publications
  • Guide to Concrete Floor
    GUIDE TO CONCRETE FLOOR Our know-how for your applications Guide to Concrete Floor Applications 2 Guide to Concrete Floor Applications Contents Concrete ........................................................ 4 Concrete Vibration ....................................... 6 Floors of Concrete ........................................ 9 Preliminary Planning ................................. 11 Laying Floors ............................................... 12 Sideforms and Screed Guides ............................................ 13 Track Rail System ....................................... 23 Fixed Rail Supports .................................... 24 Floors on Floors Structures Cast in Situ .................................................. 25 Cleaning, pre-moistening, etc. ................. 27 Conversion Tables ...................................... 41 Glossary ....................................................... 42 3 Guide to Concrete Floor Applications Concrete Concrete is a mixture of water, cement, sand and stone. The cement content affects concrete properties. A high Water content divided with cement gives w/c-ratio. The cement content gives a high strength whereas shrinkage water/cement-ratio is a theoretical average value and it unfortunately also will increase. may change during transport or vibration. What does concrete consist of? Cement W/C ratio Concrete is a mixture of water, cement, Cement and water are two important com- Water/cement-ratio means the ratio relation sand and stone. These four components ponents. water (kg) per cubic meter of concrete can be varied to a great extent and the Cement content means the amount of divided by cement content. It can be any- characteristics of the mix and the hard, cement by weight per cubic meter concrete thing from 0.80 to 0.30 at the mixing plant hydrated product itself can thereby be and can vary from 500 down to 250 kg per or in truck mixer. changed to a great extent. cubic meter. Many architects and engineers think that it is the only factor you have to worry about when you want quality concrete.
    [Show full text]
  • Alkali-Silica Reactivity: an Overview of Research
    SHRP-C-342 Alkali-Silica Reactivity: An Overview of Research Richard Helmuth Construction Technology Laboratories, Inc. With contributions by: David Stark Construction Technology Laboratories, Inc. Sidney Diamond Purdue University Micheline Moranville-Regourd Ecole Normale Superieure de Cachan Strategic Highway Research Program National Research Council Washington, DC 1993 Publication No. SHRP-C-342 ISBN 0-30cL05602-0 Contract C-202 Product No. 2010 Program Manager: Don M. Harriott Project Maxtager: Inam Jawed Program AIea Secretary: Carina Hreib Copyeditor: Katharyn L. Bine Brosseau May 1993 key words: additives aggregate alkali-silica reaction cracking expansion portland cement concrete standards Strategic Highway Research Program 2101 Consti!ution Avenue N.W. Washington, DC 20418 (202) 334-3774 The publicat:Lon of this report does not necessarily indicate approval or endorsement by the National Academy of Sciences, the United States Government, or the American Association of State Highway and Transportation Officials or its member states of the findings, opinions, conclusions, or recommendations either inferred or specifically expressed herein. ©1993 National Academy of Sciences 1.5M/NAP/593 Acknowledgments The research described herein was supported by the Strategic Highway Research Program (SHRP). SHRP is a unit of the National Research Council that was authorized by section 128 of the Surface Transportation and Uniform Relocation Assistance Act of 1987. This document has been written as a product of Strategic Highway Research Program (SHRP) Contract SHRP-87-C-202, "Eliminating or Minimizing Alkali-Silica Reactivity." The prime contractor for this project is Construction Technology Laboratories, with Purdue University, and Ecole Normale Superieure de Cachan, as subcontractors. Fundamental studies were initiated in Task A.
    [Show full text]
  • Reinforced Concrete Failure Mechanisms
    Reinforced Concrete Failure Mechanisms Best Practices in Dam and Levee Safety Risk Analyses Part E – Concrete Structures Chapter E-2 Last modified June 2017, Presented July 2019 Reinforced Concrete Failure Mechanisms OUTLINE: • Types of Structures • Spillway Piers • Navigation Lock Walls • Floodwalls • Slabs • Buttresses • Factors influencing strength and stability of reinforced concrete sections • National code requirements in the context of risk • Considerations when determining risk analysis failure probabilities based on structural analysis results • Typical event tree of the progression of failure 2 Reinforced Concrete Failure Mechanisms OBJECTIVES: • Get a broad overview of potential failure modes for different kinds of reinforced concrete structures • Understand the mechanisms that affect reinforced concrete failures • Understand how to construct an event tree to represent reinforced concrete failures • Understand how to estimate event probabilities and probability of breach Reinforced Concrete Failure Mechanisms SUMMARY OF KEY CONCEPTS: • Significant uncertainty for reinforced concrete failure mechanisms under seismic loading due to limited case histories • Concrete and reinforcement material properties can be determined with confidence for dams and floodwalls. • Type and duration of loading is important to understand – consider both static and earthquake loading • Ductile and Brittle Failure mechanisms • Seismic reinforcement details have changed dramatically over the past few decades; older concrete hydraulic structures may be
    [Show full text]
  • Slab on Grade Reinforcing Design
    PDHonline Course S132 (1 PDH) Slab on Grade Reinforcing Design Instructor: D. Matthew Stuart, P.E., S.E., F.ASCE, F.SEI, SECB, MgtEng 2013 PDH Online | PDH Center 5272 Meadow Estates Drive Fairfax, VA 22030-6658 Phone & Fax: 703-988-0088 www.PDHonline.org www.PDHcenter.com An Approved Continuing Education Provider www.PDHcenter.com www.PDHonline.org Materials: The most common reinforcement associated with slabs-on-grade is welded wire fabric. However, this is not the only means of reinforcing slabs. In some cases deformed bars are used in order to assure that the reinforcement is placed at the correct depth within the slab and not damaged during placement. In either case when using deformed bars or welded wire fabric, it is essential that adequate support of the steel is provided. Source: eHow.com Welded Wire Fabric: When using welded wire fabric, prefabricated sheets should be used in lieu of rolled fabric in order to help assure proper location of the steel within the concrete. In either case a minimum of one chair per 25 square feet of mesh should be used to adequately support the reinforcement above the sub-grade. The table provided in this slide lists common styles of welded wire fabric, including the “old” and "new" designations. Although the "new" designations are more than 20 years old, many engineers find this cross-reference helpful. Common Styles of Welded Wire Fabric Steel Area Style Designation Sq. in. per ft. Weight Lbs. per New Designation Old Designation Longitudinal Transverse 100 SF (by W-number) (by steel wire gauge) ROLLS 6x6-W1.4xW1.4 6x6-10x10 .028 .028 21 6x6-W2.0xW2.0 6x6-8x8* .040 .040 29 6x6-W2.9xW2.9 6x6-6x6 .058 .058 42 6x6-W4.0xW4.0 6x6-4x4 .080 .080 58 4x4-W1.4xW1.4 4x4-10x10 .042 .042 31 4x4-W2.0xW2.0 4x4-8x8* .060 .060 43 4x4-W2.9xW2.9 4x4-6x6 .087 .087 62 4x4-W4.0xW4.0 4x4-4x4 .120 .120 85 SHEETS 6x6-W2.9xW2.9 6x6-6x6 .058 .058 42 6x6-W4.0xW4.0 6x6-4x4 .080 .080 58 6x6-W5.5xW5.5 6x6-2x2** .110 .110 80 4x4-W4.0xW4.0 4x4-4x4 .120 .120 85 * Exact W-Number size for 8 gauge is W2.1.
    [Show full text]
  • SLAB FORMWORK DESIGN USING GENETIC ALGORITHM Formwork Design Using GA
    SLAB FORMWORK DESIGN USING GENETIC ALGORITHM Formwork design using GA H AL-TABTABAI, A.P. ALEX and R JAMES Department of Civil Engineering, College of Engineering and Petroleum, University of Kuwait, Safat, Kuwait Durability of Building Materials and Components 8. (1999) Edited by M.A. Lacasse and D.J. Vanier. Institute for Research in Construction, Ottawa ON, K1A 0R6, Canada, pp. 2407-2418. Ó National Research Council Canada 1999 Abstract A method to design cost-optimum slab formwork components is proposed in this paper. Genetic Algorithms (GAs), a technique based on the principles of natural selection and evolution, is applied to solve the optimisation problem. GAs search from a population of possible solutions limited by a set of constraints. The cost of form components and labor involved, were considered for the formulation of the objective function of the optimisation problem. The bending moment, shear, maximum deflection, imposed ACI code provisions, etc., were used as constraints for the optimisation problem. Application of GA to the formwork design problem provides optimum design parameters such as the optimum cross section for form members, optimum spacing of form members, etc., while minimising the total cost. Formwork made either from wood, wood-metal composite or metal alone can be designed using the proposed technique. The paper presents the case of general formwork design, however, the method as a whole readily applies to the design of formwok for elevated slabs and high rise concrete elements. Keywords: Formwork design, genetic algorithm, optimisation, construction cost 1 Introduction Slab formwork holds and provides support for freshly placed concrete through a framework of sheathing, joists, stringers and shores (Fig.
    [Show full text]
  • A Computational Study of the Shear Behavior of Reinforced Concrete Beams Affected from Alkali–Silica Reactivity Damage
    materials Article A Computational Study of the Shear Behavior of Reinforced Concrete Beams Affected from Alkali–Silica Reactivity Damage Bora Gencturk 1,* , Hadi Aryan 1, Mohammad Hanifehzadeh 1, Clotilde Chambreuil 2 and Jianqiang Wei 3 1 Sonny Astani Department of Civil and Environmental Engineering, University of Southern California, 3620 S. Vermont Avenue, KAP 210, Los Angeles, CA 90089-2531, USA; [email protected] (H.A.); [email protected] (M.H.) 2 LMT—Laboratoire de Mécanique et Technologie, University Paris-Saclay, ENS Paris-Saclay, CNRS, 91190 Gif-sur-Yvette, France; [email protected] 3 Department of Civil and Environmental Engineering, University of Massachusetts, Lowell, MA 01854-5104, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-(213)-821-1036; Fax: +1-(213)-744-1426 Abstract: In this study, an investigation of the shear behavior of full-scale reinforced concrete (RC) beams affected from alkali–silica reactivity damage is presented. A detailed finite element model (FEM) was developed and validated with data obtained from the experiments using several metrics, including a force–deformation curve, rebar strains, and crack maps and width. The validated FEM was used in a parametric study to investigate the potential impact of alkali–silica reactivity (ASR) degradation on the shear capacity of the beam. Degradations of concrete mechanical properties were correlated with ASR expansion using material test data and implemented in the FEM for Citation: Gencturk, B.; Aryan, H.; different expansions. The finite element (FE) analysis provided a better understanding of the failure Hanifehzadeh, M.; Chambreuil, C.; mechanism of ASR-affected RC beam and degradation in the capacity as a function of the ASR Wei, J.
    [Show full text]
  • How to Make Concrete More Sustainable Harald Justnes1
    Journal of Advanced Concrete Technology Vol. 13, 147-154, March 2015 / Copyright © 2015 Japan Concrete Institute 147 Scientific paper How to Make Concrete More Sustainable Harald Justnes1 A selected paper of ICCS13, Tokyo 2013. Received 12 November 2013, accepted 16 February 2015 doi:10.3151/jact.13.147 Abstract Production of cement is ranking 3rd in causes of man-made carbon dioxide emissions world-wide. Thus, in order to make concrete more sustainable one may work along one or more of the following routes; 1) Replacing cement in con- crete with larger amounts of supplementary cementing materials (SCMs) than usual, 2) Replacing cement in concrete with combinations of SCMs leading to synergic reactions enhancing strength, 3) Producing leaner concrete with less cement per cubic meter utilizing plasticizers and 4) Making concrete with local aggregate susceptible to alkali silica reaction (ASR) by using cement replacements, thus avoiding long transport of non-reactive aggregate. 1 Introduction SCMs, also uncommon ones like calcined marl 2. Replacing cement in concrete with combinations of The cement industry world-wide is calculated to bring SCMs leading to synergic reactions enhancing about 5-8% of the total global anthropogenic carbon strength dioxide (CO2) emissions. The general estimate is about 3. Producing leaner concrete with less cement per cubic 1 tonne of CO2 emission per tonne clinker produced, if meter utilizing plasticizers. fossil fuel is used and no measures are taken to reduce it. 4. Making concrete with local aggregate susceptible to The 3rd rank is not because cement is such a bad mate- alkali silica reaction (ASR) by using cement re- rial with respect to CO2 emissions, but owing to the fact placements, thus avoiding long transport of non- that it is so widely used to construct the infrastructure reactive aggregate and buildings of modern society as we know it.
    [Show full text]
  • Direct Design Method for Prestressed Concrete Slabs
    DIRECT DESIGN METHOD FOR PRESTRESSED CONCRETE SLABS Chen-Hwa Wang Associate Professor of Civil Engineering and Mechanics The Catholic University of America Washington, D.C. Although several methods such as with maximum bending moment moment-balancing( 1 , load-balanc- may be considered as the control ing( 2 ) and structural membrane section. However, a continuous slab theory (31 can be applied to design has several maximum moment peaks of slabs, none of these is a direct in the middle portion of spans and design method. At present, the load- over supports. Therefore, selection balancing method is widely applied of a control section which has the because it is simpler than the others. largest maximum moment may not It is a trial and analysis approach necessarily provide the optimum de- for obtaining the expected stresses sign. Conventional reinforcing steel and behavior in a slab by the proper or discontinuous tendons for resist- determination of slab thickness, bal- ing partial moment stress at several anced load, eccentricity, and applied sections with moments higher than prestressing. Since this approach is at the control section becomes more time consuming and difficult to a practical and economical. Hence, new design engineer in practice, the selection of the control section this paper presents a straightfor- really depends on the type of struc- ward method and procedures for de- ture and engineering judgment sign of slabs with consideration of whether or not to use mild steel re- the selection of control sections and inforcement or local prestressing in distribution of prestressing. Illustra- the design. In any case, the selection tive examples are also included for of a control section in each direction practical application.
    [Show full text]
  • Two-Way Joist (Waffle Slab) Concrete Floor System Analysis and Design
    Two-Way Joist Concrete Slab Floor (Waffle Slab) System Analysis and Design Version: May-18-2017 Two-Way Joist Concrete Slab Floor (Waffle Slab) System Analysis and Design Design the concrete floor slab system shown below for an intermediate floor with partition weight of 50 psf, and unfactored live load of 100 psf. The lateral loads are independently resisted by shear walls. A flat plate system will be considered first to illustrate the impact longer spans and heavier applied loads. A waffle slab system will be investigated since it is economical for longer spans with heavy loads. The dome voids reduce the dead load and electrical fixtures can be fixed in the voids. Waffle system provides an attractive ceiling that can be left exposed when possible producing savings in architectural finishes. The Equivalent Frame Method (EFM) shown in ACI 318 is used in this example. The hand solution from EFM is also used for a detailed comparison with the model results of spSlab engineering software program from StructurePoint. Figure 1 - Two-Way Flat Concrete Floor System Version: May-18-2017 Contents 1. Preliminary Member Sizing ..................................................................................................................................... 1 2. Flexural Analysis and Design................................................................................................................................. 13 2.1. Equivalent Frame Method (EFM) ..................................................................................................................
    [Show full text]
  • Formwork.Pdf
    Formwork INTRODUCTION ............................................................................................................................................................ 3 DESIGN REQUIREMENTS ............................................................................................................................................... 4 FACTORS RELATING TO FORMWORK ........................................................................................................................... 6 HIGH WALL FORMWORK .......................................................................................................................................... 6 Timber Framed Formwork. ....................................................................................................................................... 7 SHEATHING ............................................................................................................................................................... 8 WALL TYING SYSTEMS .............................................................................................................................................. 8 CONSTRUCTION JOINTS ............................................................................................................................................ 9 SLIPFORM ............................................................................................................................................................... 10 CLIMBING OR JUMP FORMS ..................................................................................................................................
    [Show full text]
  • Formation of Polymer Micro-Agglomerations in Ultralow-Binder-Content Composite Based on Lunar Soil Simulant
    Available online at www.sciencedirect.com ScienceDirect Advances in Space Research 61 (2018) 830–836 www.elsevier.com/locate/asr Formation of polymer micro-agglomerations in ultralow-binder-content composite based on lunar soil simulant Tzehan Chen a, Brian J. Chow b, Ying Zhong a, Meng Wang b, Rui Kou b, Yu Qiao a,b,⇑ a Program of Materials Science and Engineering, University of California – San Diego, La Jolla, CA 92093, USA b Department of Structural Engineering, University of California – San Diego, La Jolla, CA 92093-0085, USA Received 9 August 2017; received in revised form 25 October 2017; accepted 27 October 2017 Available online 6 November 2017 Abstract We report results from an experiment on high-pressure compaction of lunar soil simulant (LSS) mixed with 2–5 wt% polymer binder. The LSS grains can be strongly held together, forming an inorganic-organic monolith (IOM) with the flexural strength around 30–40 MPa. The compaction pressure, the number of loadings, the binder content, and the compaction duration are important factors. The LSS-based IOM remains strong from À200 °C to 130 °C, and is quite gas permeable. Ó 2017 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Binder content; Lunar regolith; Structural material; In-situ resource utilization 1. Introduction A major component of lunar soil is silica. While, once heated to above 1200 °C, silica grains can be fused In the next a few decades, building large-scale lunar together, the thermal processing consumes a large amount bases and/or research facilities on the Moon will probably of energy (Taylor and Meek, 2005).
    [Show full text]
  • Properties and Applications of Fiber Reinforced Concrete
    JKAU: Eng. Sci., Vol. 2, pp. 49-6~ (1410 A.H./19lJlI A.D.) Properties and Applications of Fiber Reinforced Concrete FAISAL FOUAD WAFA Associate Professor, Civil Engineering Department, Faculty ofEngineering, King Abdulaziz University, Jeddah, Saudi Arabia. ABSTRACT. Fiber reinforced concrete (FRC) is a new structural material which is gaining increasing importance. Addition of fiber reinforcement in discrete form improves many engineering properties of concrete. Currently, very little research work is being conducted within the King­ dom using this new material. This paper describes the different types of fib­ ers and the application of FRC in different areas. It also presents the result of research about the mechanical properties of FRC using straight as well as hooked steel fibers available in the region, Introduction Concrete is weak in tension and has a brittle character. The concept of using fibers to improve the characteristics of construction materials is very old. Early applications include addition of straw to mud bricks, horse hair to reinforce plaster and asbestos to reinforce pottery. Use of continuous reinforcement in concrete (reinforced con­ crete) increases strength and ductility, but requires careful placement and labour skill. Alternatively, introduction offibers in discrete form in plain or reinforced con­ crete may provide a better solution. The modern development of fiber reinforced concrete (FRC) started in the early sixties(1J. Addition of fibers to concrete makes it a homogeneous and isotropic material. When concrete cracks, the randomly oriented fibers start functioning, arrest crack formation and propagation, and thus improve strength and ductility. The failure modes of FRC are either bond failure be­ tween fiber and matrix or material failure.
    [Show full text]