Sensitivity of an alkali-silica reaction kinetics model to diffusion and reactive mechanisms parameters

Abstract

Alkali-silica reaction (ASR) expansion is due to a combination of chemo-mechanical mechanisms. To obtain realistic predictions, modelling developed at the material scale has to consider reactive transport and mechanical issues. Numerous input variables concerning aggregate and cement paste properties are thus necessary. The uncertainties that affect such variables make the prediction of the ASR phenomenon random and thus need to be considered in a probabilistic context. To reduce the stochastic dimension for a further probabilistic analysis, a sensitivity analysis using the Morris method is conducted here, at different dates, on an ASR model developed at the material scale. It is illustrated by a combined sensitivity analysis of both the total volume of ASR products formed over time and the corresponding expansion. The work shows the relative impact of transport and reactive mechanisms on ASR kinetics. Moreover, the most significant parameters are not the same for laboratory accelerated expansion tests as for real structures under low temperatures. This highlights the relative impact of ASR mechanisms according to temperature.