Chemistry of Alkali-Silica Reaction

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AbstractAlkali-silica reaction (ASR) is a major cause of concrete deterioration. The overall goal of this research project is to combine chemical and mechanical approaches tosubstantially advance fundamental understanding of ASR and to provide a basis for development of more effectiveaccelerated tests and for prevention of damage. The objectives are: 1) to understand the molecular and nanometer-scale structure of ASR gels and how the structure is affected by conditions of formation, 2) to understand themolecular and nanostructural processes that produce the gel, the chemical and structural controls on gelcomposition, and the kinetics of gel formation and subsequent transformations, 3) to understand the effects ofaggregate type on the composition and structure of ASR gel and on the kinetics of gel formation, 4) to understandthe chemical and structural aspects of gel that control swelling behavior, and 5) to understand the relationshipsbetween the macroscopic structural expansion of concrete undergoing ASR and the details of gel formation andswelling by developing a finite element model of concrete expansion that can be used to more effectively predictand evaluate the engineering effects of ASR.The proposed research will have intellectual impact in civil engineering, geological science, andmaterials science. It will provide a detailed understanding of the chemistry of an important concrete deteriorationmechanism, knowledge of the molecular structure of a class of hydrous silicates, ASR gel andestablish a link between molecular structure and swelling behavior. It will establish a microstructural-based modelthat links ASR chemistry and concrete expansion. Knowledge gained through this research will beincorporated into education in both civil engineering and geology. The project will enhance interactions betweenengineering and geology. And the proposed research will enhance minority education through participation Jackson State University, a historically black institution.