Miras Mamirov Thesis Defense
Optimization of Pavement Concrete Based on Theoretical and Experimental Particle Packing and Pavemen
3:00 pm
Peter Kiewit Institute Room: 100A
April 9
3:00 PM
PKI 100A
Advisor: Jiong Hu
The main objective of this study was to evaluate the effect of particle packing optimization and cement reduction in Nebraska slip-form pavement concrete performance. A literature review was conducted to examine different optimization tools, quality control tests, and historical data of Nebraska Department of Transportation (NDOT) mixtures. It was found that the Modified Toufar Model has good potential in optimizing particle packing and predict packing degrees. The combined void content test was found to be useful to justify optimized gradations experimentally. Two specific pavement concrete workability tests, Box test, and VKelly test, were used to evaluate the effect of cement reduction and optimized aggregate gradation on pavement concrete workability. The Box test ranking was modified to provide a more detailed and objective evaluation. As one of the goals of the study was to allow the maximum use of local materials, locally available cementitious materials and aggregates were selected. It was found that East and West Nebraska have some differences in aggregate sources. Therefore, aggregates from both regions were collected and used in the study. Aggregate system analysis has shown that experimental packing from the combined void content test has good correlation with estimated packing from the Modified Toufar Model. Results also demonstrated that the current aggregate combination is not the optimum gradation and can be improved. The experimental program included in this study consisted of three Phases. Phase 1 focused on obtaining promising aggregate blends by
maintaining the standard cement content (564 lb/yd3, 335 kg/m3). Fresh concrete properties were the main criteria to select promising blends. Phase 2 included evaluation of the performance of pavement concrete with cement content reduced by 0.5 sacks (47 lb/yd3, 28 kg/m3) step for other reference and optimized aggregate blends. Results justified that when optimum gradation is used, less cement is needed in the mixture. Phase 3 is the performance evaluation phase, which included testing reference mix and few promising mixes for setting time, modulus of elasticity, free shrinkage, restrained shrinkage, and freeze/thaw resistance. Finally, a mix design procedure incorporating theoretical and experimental particle packing, and using excess paste-to-aggregates ratio as the control parameter was proposed.
3:00 PM
PKI 100A
Advisor: Jiong Hu
The main objective of this study was to evaluate the effect of particle packing optimization and cement reduction in Nebraska slip-form pavement concrete performance. A literature review was conducted to examine different optimization tools, quality control tests, and historical data of Nebraska Department of Transportation (NDOT) mixtures. It was found that the Modified Toufar Model has good potential in optimizing particle packing and predict packing degrees. The combined void content test was found to be useful to justify optimized gradations experimentally. Two specific pavement concrete workability tests, Box test, and VKelly test, were used to evaluate the effect of cement reduction and optimized aggregate gradation on pavement concrete workability. The Box test ranking was modified to provide a more detailed and objective evaluation. As one of the goals of the study was to allow the maximum use of local materials, locally available cementitious materials and aggregates were selected. It was found that East and West Nebraska have some differences in aggregate sources. Therefore, aggregates from both regions were collected and used in the study. Aggregate system analysis has shown that experimental packing from the combined void content test has good correlation with estimated packing from the Modified Toufar Model. Results also demonstrated that the current aggregate combination is not the optimum gradation and can be improved. The experimental program included in this study consisted of three Phases. Phase 1 focused on obtaining promising aggregate blends by
maintaining the standard cement content (564 lb/yd3, 335 kg/m3). Fresh concrete properties were the main criteria to select promising blends. Phase 2 included evaluation of the performance of pavement concrete with cement content reduced by 0.5 sacks (47 lb/yd3, 28 kg/m3) step for other reference and optimized aggregate blends. Results justified that when optimum gradation is used, less cement is needed in the mixture. Phase 3 is the performance evaluation phase, which included testing reference mix and few promising mixes for setting time, modulus of elasticity, free shrinkage, restrained shrinkage, and freeze/thaw resistance. Finally, a mix design procedure incorporating theoretical and experimental particle packing, and using excess paste-to-aggregates ratio as the control parameter was proposed.
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