Strong Coupling of Freeze-Thaw Cycles and Alkali Silica Reaction - Multi-scale Poro-mechanical Approach to Concrete Damages -

This paper aims to upgrade the poro-mechanical scheme to simulate concrete volume change and damages which are strongly coupled with both alkali silica reaction (ASR) and freeze-thaw cycles (FTC). The interaction of two impacts are modeled by considering ASR gel intrusion and ice formation in micro pores and crack gaps, gel movement and unfrozen water suction into entrained air, gel and water migration through cracks as well as equilibrium and mass conservation of both concrete skeleton and mixed pore substances. For the assessment how the proposed numerical scheme works, sequence of events on ASR and FTC is focused on. It shows that ASR can reduce the FTC expansion for nonair- entrained (non-AE) case, but increase the frost damage for air-entrained (AE) concrete. Similarly, the FTC damaged concrete will have a smaller ASR expansion for non-AE case, but a greater expansion when AE admixture agent is dosed. The simulated behaviors also agree well with past experiments of combined ASR and FTC. Finally, the analysis on short-term strength shows that the ASR damaged concrete has a higher residual compressive strength and ductility rather than FTC damaged one due to viscous ASR gel which stand for broken symmetry of damage fields.