Chemo-Mechanical Micromodel for Alkali-Silica Reaction

This paper presents a two-stage numerical model for alkali-silica reaction (ASR)/stress analysis in concrete. The coupled analytical chemo-mechanical model developed by Suwito et al. was modified to include the effects of internal moisture and ion concentration on the transport properties of concrete. A finite difference model was used to simulate the coupled diffusion of alkali into concrete and subsequent ASR gel into pores surrounding the aggregates. A finite element model was then subsequently used to perform a nonlinear analysis. This model is invoked from the master finite difference model, resulting in a coupled chemo-mechanical simulation of ASR-affected concrete with aggregates of different shapes and sizes. Throughout this analysis, the authors keep track of the vertical and lateral expansions of the concrete with time which, in turn, are transformed into equivalent anisotropic coefficients of ASR expansion. Finally, the accuracy of the model is assessed through comparison with simulated laboratory tests.