This study set out to investigate the effect of gel migration through micro-pores and cracks on concrete expansion caused by alkali-silica reaction (ASR). First, sensitivity analyses with permeation of produced silica gel were conducted by using a computational scheme of multi-scale poro-mechanics. Then, silica gel movements were found to substantially affect the ASR expansion of concrete with the possibility of its scale effect being rooted in the drugging force when the silica gel is in motion. With accelerated ASR tests of mortar, the predicted scale effects were experimentally verified and the permeation of gel was inversely identified in terms of multi-scale mechanics. Here, the effect of alkali ion leaching on the scale-dependency was also discussed in view of chemo-physics as well as mechanics of produced gel migration. The measured characteristic scale-dependency in the experiment can be also simulated by nonlinear analysis of smeared cracks coupled with gel generation, migration and alkali ion leaching.

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