Damage Analyses of Concrete Dams Subject to Alkali-Silica Reaction

The durability of concrete can be reduced by several chemical phenomena, among them the alkali-silica reaction (ASR) plays a fundamental role. Such reaction can have a severe impact on structure safety and functioning. This work deals with the evaluation of the effects of ASR in existing concrete dams. To this purpose, a phenomenological two-phase isotropic damage model, describing the degradation of concrete, is presented and used to simulate the behaviour of concrete dams affected by ASR. This model takes into account the simultaneous influence of both humidity and temperature through two uncoupled diffusion analyses: the heat diffusion analysis and the moisture diffusion analysis. The role of the temperature and humidity fields variations on the development of the deleterious reactions is discussed in the case of an arch dam. The numerical analyses, performed with the proposed thermo-hydro-damage model, allowed to predict the structural behaviour both in terms of reaction extent and increase of crest displacements.