Simulating the Effect of ASR on the Performance of Concrete Structures

Concrete is a time-dependent and multi-scale composite. Alkalis in cement react with reactive silica in aggregate in the presence of water and forms a gel in what is known as alkali-silica reaction (ASR). When ASR gel absorbs water, it swells. Swelling of ASR gels can damage concrete and cause cracking which reflects on long-term structural performance. In this paper, the mechanical consequences of ASR on concrete are simulated using a discrete homogenization model. Representative volume element (RVE) of concrete is established as a cluster of cement paste and aggregate particles connected using an interfacial transition zone (ITZ), which includes contact and cracking mechanisms to consider particle interaction. The mechanical evolution of concrete subjected to ASR is achieved from microstructural behaviors: volume expansion of reactive elements induces internal stresses and cause debonding and cracking. The mechanical evolution of concrete characteristics due to continuous cement hydration is also considered. The constitutive model of concrete is attained via the homogenization approach. The proposed method allows considering the effect of ASR on performance of concrete structures. A case study, in the literature, is used to demonstrate the efficiency of the proposed meso-scale homogenization approach. The proposed model shows good agreement with experimental observations of concrete behavior with ASR.