Expansion and deterioration of concrete due to ASR: Micromechanical modeling and analysis

A multi-scale micromechanics model is proposed to describe the expansion and deterioration of concrete due to Alkali-Silica Reaction (ASR). The mechanics of ASR induced deterioration of a Representative Elementary Volume (REV) of concrete is modeled through a synthesis of distributed microcracking and mean-field homogenization. At the microscale, ASR-gel-pressure induced microcrack growth in and around the reactive aggregates is modeled using the framework of linear elastic fracture mechanics. Mean-field homogenization across multiple scales is used to obtain the overall expansion and degradation of the material. By specifying the spatial distribution of the pressurizing gel, two different ASR mechanisms associated with “slowly” and “rapidly” reactive aggregates can be modeled. Experimental data for concrete degradation as a function of the macroscopic expansion is found to lie within the theoretical upper and lower bounds that characterize the distribution of the gel in the aggregate or the cement paste.