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Consolidating Concrete NDOT Research Report Report No. 077-06-803 Prescriptive Mixture Design of Self- Consolidating Concrete April 2009 Nevada Department of Transportation 1263 South Stewart Street Carson City, NV 89712 Disclaimer This work was sponsored by the Nevada Department of Transportation. The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the State of Nevada at the time of publication. This report does not constitute a standard, specification, or regulation. Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. RDT 09-077 4. Title and Subtitle 5. Report Date Prescriptive Mixture Design of Self-Consolidating Concrete May 2008 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Nader Ghafoori, Hamidou Diawara 9. Performing Organization Name and Address 10. Work Unit No. University of Nevada, Las Vegas 11. Contract or Grant No. Civil and Environmental Engineering Department 4505 Maryland Parkway, Box 454015 P077-06-803 Las Vegas, Nevada 89154-4015 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Nevada Department of Transportation Final Report 1263 S. Stewart Street Carson City, Nevada 89712 14. Sponsoring Agency Code 15. Supplementary Notes 16. Abstract This research studied the influence of aggregate size, admixture source, hauling time, temperature and pumping on the fresh and hardened properties of three distinct groups of self-consolidating concretes (SCC.) The first phase of investigation compared dosages of admixtures and properties of the variants. The second phase evaluated the influence of hauling times, temperature and pumping on the concrete. 17. Key Words 18. Distribution Statement Concrete Aggregates, Self Compacting Concrete, Concrete Setting, No restrictions Atmospheric Temperature, Admixtures, Concrete Hardening 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 295 N/A Form DOT F 1700.7 (8-72) Reproduction of completed page authorized. PRESCRIPTIVE MIXTURE DESIGN OF SELF-CONSOLIDATING CONCRETE NDOT RESEARCH Agreement No: P077-06-803 Report Submitted to Nevada Department of Transportation Research Division ATTN: Dr. Tie He 1263 S. Stewart Street Carson City, NV 89712 By Nader Ghafoori, Ph.D., P.E., Professor and Chairman and Hamidou Diawara, MSc, Doctorate student and Research assistant University of Nevada, Las Vegas Civil and Environmental Engineering Department 4505 Maryland Parkway Box 454015 Las Vegas, Nevada 89154-4015 Phone: (702)895-3701 Fax: (702)895-3936 April 2009 (revised) ABSTRACT OF THE REPORT PRESCRIPTIVE MIXTURE DESIGN OF SELF-CONSOLIDATING CONCRETE The research investigation presented herein was intended to study the influence of parameters such as aggregate size, admixture source, hauling time, temperature and pumping on the fresh and hardened properties of three distinct groups of self- consolidating concretes (SCC). Within each group, the selected self-consolidating concretes were made with a constant water-to-cementitious materials ratio, a uniform cementitious materials (cement and fly ash) content, and a constant coarse-to-fine aggregate ratio that provided the optimum aggregate gradation. Three coarse aggregate sizes (ASTM C 33 #8, #7, and #67) obtained from two different quarries were investigated. Four sources of polycarboxylate-based high range water reducing admixtures (HRWRA), along with their corresponding viscosity modifying admixtures (VMA), were used. All raw materials were evaluated for their physico-chemical characteristics. The investigation presented herein was divided into two major phases. The first phase aimed at: (1) comparing the optimum dosage requirement of four different sources of polycarboxylate-based HRWRA and VMA in attaining the target slump flow of 20 inches (508 mm), 25 inches (635 mm), and 28 inches (711 mm), T50 of 2 seconds or more, and a visual stability index (VSI) of 0 (Highly stable concrete) or 1 (Stable concrete), (2) evaluating the flow ability/viscosity, the dynamic stability, the passing ability, the filling ability, and the static segregation resistance of trial self-consolidating concretes, and (3) examining the properties of the selected SCCs as related to air content, bleeding, time of setting, adiabatic temperature, demolded unit weight, compressive strength and modulus of elasticity. In the second phase, the influences of hauling time, temperature and pumping on fresh performances of the selected self-consolidating concretes were evaluated. Seven different temperatures 109, 96, 83, 70, 57, 44 and 31 oF (43, 36, 28, 21, 14, 7 and -0.5 oC) and nine different hauling times (10, 20, 30, 40, 50, 60, 70, 80 and 90 minutes) were used to determine the loss in unconfined workability, dynamic stability, and flowability rate of the designed matrices. The adverse influence of the above-mentioned variables was remediated by providing sufficient initial optimum admixture dosages (overdosing method) that resulted in achieving the intended fresh properties of the designed SCCs for different hauling times and temperatures. Moreover, the second phase of the study addressed the effect of pumping at various distances of 100, 200 and 300 ft (30, 60 and 90 m) on the flow ability, passing ability, stability, rheology (yield stress and plastic viscosity), air content and air void characteristics of the selected self-consolidating concretes. For the test results of this study the following conclusions can be drawn: • Irrespective of the self-consolidating concrete groups, the optimum dosages requirement of HRWRA in obtaining a uniform slump flow and visual stability index was highest for the source A, followed by the sources C, B, and D in descending order. On the other hand, the required VMA dosage was highest for the source A and remained uniform for the sources B, C, and D. With proper proportioning, self-consolidating concrete with acceptable flow ability, plastic viscosity, dynamic and static stabilities, passing ability, and filling ability can be achieved with any of the four selected admixture sources. • The fresh performance of self-consolidating concrete was affected by hauling time. The effects were manifested in the form of loss in flow ability, and gain in plastic viscosity and dynamic stability. A remediation technique consisting of admixture overdosing was able to produce SCCs with a similar flow ability, plastic viscosity, dynamic stability, and passing ability to those obtained at the control hauling time. • The fresh performance of self-consolidating concrete was affected by hot temperatures in the form of significant decrease in unconfined workability, substantial increase in flow rate or plastic viscosity per inference, and improvement in dynamic stability of the freshly-mixed SCCs. The cold temperature affected the fresh performance of the selected self-consolidating concretes by a marginal gain in flow ability, small variation in flow rate, and an increase in the resistance to segregation from VSI of 1 to 0 for the matrices only made with slump flow of 28 inches (711mm), when compared to those obtained under the control temperature. The VSI of the trial SCCs prepared with slump flows of 20 and 25 inches (508 and 635 mm) were unaffected by the selected cold temperatures. A remediation method by way of admixture overdosing was successful to reverse the change in fresh properties of the selected self-consolidating concretes in elevated temperatures. The selected self-consolidating concretes did not require any remediation in cold temperatures. • The pumping adversely affected the fresh performance of the self-consolidating concrete by decreasing the unconfined workability, flow rate, and passing ability; and by increasing the dynamic segregation resistance. The impact of pumping on the rheological properties of self-consolidating concrete was manifested by a moderate increase in relative yield stress and a significant decrease in relative plastic viscosity. In general, irrespective of the slump flow and pumping distance, the air content remained unaffected by the pumping action. However, the air voids characteristics were affected by the pumping without exceeding the recommend limits. The pumping generated larger sizes of the air bubbles (or lower specific area) accompanied with increases in the spacing factors. ACKNOWLEDGMENTS The authors would like to acknowledge the financial support of the Nevada Department of Transportation, Grant number P 077-06-803. Special thanks are extended to the NDOT research chief, Dr. Tie He, and the NDOT research panel for their valuable suggestions throughout the project. Thanks are also given to a number of admixture manufacturers and concrete suppliers who contributed materials and equipments used in this investigation. Their names are withheld to avoid any concern of commercialization or private interest. TABLE OF CONTENTS i Page No. LIST OF TABLES x LIST OF FIGURES xiii GLOSSARY xix RESEARCH OBJECTIVE xxi TASK 1: DEVELOPMENT OF SELF-CONSOLIDATING CONCRETE SPECIFICATIONS ACCEPTANCE CRITERIA AND TEST METHODS 1 1.1 DEVELOPMENT OF SELF-CONSOLIDATING CONCRETE SPECIFICATIONS ACCEPTANCE CRITERIA AND TEST METHODS 2 1.2 GENERAL BACKGROUND ON SELF-CONSOLIDATING CONCRETE 1.2.1 Aggregates 4 1.2.1.1 Grading 5 1.2.1.2 Shape and texture 5 1.2.1.3 Bulk density or unit weight 6 1.2.1.4 Specific
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