Developing Criteria for Performance-Based Concrete Specifications.

摘要

For more than 50 years now, concrete technology has advanced, but CDOT specifications for durability have remained mostly unchanged. The minimum cement content for a given strength is derived from mix design guidelines that were developed before water reducing admixtures were widely used and accepted. The minimum cement content generally controls the mix design process, with many mix designs exceeding the minimum strength requirements by 500 to 1,000 psi. Ready mix suppliers that supply to non-CDOT projects have developed mix designs that use less cement and more fly ash than CDOT mix designs and exceeded their strengths. They are able to accomplish this improvement through gradation optimization and admixture combinations. The proposed study tested current CDOT standard mix designs to determine minimum required performance criteria that will be used to develop performance-based concrete mix design criteria.