Diffusion-controlled and creep-mitigated ASR damage via microplane model: II. Material degra- dation, drying, and verification

Abstract

The theory for the material and structural damage due to the alkali-silica reaction (ASR) in concrete is calibrated and validated by finite element fitting of the main test results from the literature. The fracture mechanics aspects, and particularly the localization limiter, are handled by the crack band model. It is shown that the theory can capture the following features quite well: (1) the effects of various loading conditions and stress states on the ASR-induced expansion and its direction; (2) degradation of the mechanical properties of concrete, par- ticularly its tensile and compressive strength, and elastic modulus; (3) the effect of temperature on ASR-induced expansion; and (4) the effect of drying on the ASR, with or without simultaneous temperature effect. The finite element simulations use microplane model M7. The aging creep, embedded in M7, is found to mitigate the predicted ASR damage significantly. The crack band model is used to handle quasi-brittle fracture mechanics and serve as the localization limiter. The moisture diffusivity, both the global one for external drying and the local one for mortar near the aggregate, decreases by one to two orders of magnitude as the pore humidity drops. The fits of each experimenter’s data use the same material parameters. Close fits are achieved and the model appears ready for predicting the ASR effects in large structures.