A mesoscale discrete model for mechanical performance of concrete damaged by ASR/DEF
(This research is collaborating with Nagai lab from The University of Tokyo)
Durability issues arising from phenomena such as the alkali-silica reaction (ASR) and delayed ettringite formation (DEF) may threaten the serviceability and safety of concrete structures due to premature cracking. In many cases, these types of deterioration can even occur simultaneously and promote the development of others. Although they both show surface map cracking, the nature of the damage caused by each is different and the damage process varies also. To evaluate or predict the mechanical property degradation precisely, it is important to understand internal cracking behavior under the combined effects and numerical analysis is required for this since the information is difficult to obtain through experimentation.
In our research, a three-dimensional rigid body spring model (3D RBSM) is used to simulate the cracking and mechanical property degradation of concrete under coupled ASR and DEF. Concrete expansions induced by ASR and DEF are introduced in the model by applying initial strain on the springs of interfacial transition zone (ITZ) and mortar elements as damage history respectively. The effect of the percentage of reactive aggregate is studied in the cases of ASR damage, while different intensified expansion areas are considered in the case of DEF. Surface cracking and internal crack numbers were analyzed to correlate the mechanical reduction.
