Performance-Related Specifications for Concrete Bridge Superstructures, Volume 2: High-Performance Concrete

Abstract

This is Volume 2 of the Final Report for the project titled “Performance-Related Specifications for Concrete-Bridge Superstructures” dealing with the topic of High-Performance Concrete (HPC). The investigation of high-performance concrete included the development of optimized concrete mixtures and identifying their performance characteristics related to durability for the purpose of using these characteristics in performance–related specifications in the state of Indiana. The research effort described in this report was divided in two phases. Phase I was focused on development of concrete mixtures optimized with respect to selected performance-related parameters. During this phase, ten optimum concrete mixes have been identified from 45 mixes in terms of compressive strength, Young’s modulus of elasticity, rapid chloride penetration and chloride conductivity using a statistical design procedure. Through surface response methodology, 27 statistical models were developed for each of four parameters. Based on the models developed, 81 contour maps were generated, which indicated how performance of concrete varied in response to the change of dosages of binders at constant water-binder ratio. Based on the overlaid contour maps and the threshold values chosen for the properties of concrete, optimum concrete mixtures including Portland cement and the combinations with fly ash, silica fume and slag were identified. In Phase II of this study, the ten optimum mixtures were further evaluated with respect to mechanical properties and durability characteristics. Several different tests related to the evaluation of the resistance of concrete to chloride permeability were used: rapid chloride permeability test, chloride conductivity test, test for the resistance of concrete under DC electrical field, ponding test for the determination of the resistance of concrete to chloride penetration, and rapid test for the determination of diffusion coefficient from chloride migration. Tests related to the resistance of concrete to freezing & thawing, and scaling were also investigated. Other tests such as, the determination of drying shrinkage, and test for curing effects on the properties of high performance concrete were also evaluated in this research. Special emphasis was placed on determining and quantifying these parameters that control the ingress of the chloride ions. Based on the results generated during this research, models have been developed that allow for prediction of certain mechanical and durability-related parameters related to the mixture composition. The parameters that can be predicted include strength, rapid chloride permeability (RCP) values, and chloride diffusion coefficient. Limited validation of these models was performed using field data provided by INDOT. The strength and