Numerical simulation on damage behaviors of tile-mortar interface induced by mortar shrinkage and temperature cycles

In this study, the initiation and evolution of interfacial damage between tile and mortar induced by mortar shrinkage, temperature cycles and their coupling actions were investigated and compared based on a novel fatigue cohesive zone model for the first time. Firstly, the fatigue cohesive zone model was established by coupling a bi-linear cohesive zone model with a fatigue damage evolution model and verified by comparing with experimental values. Then, the de- formations and stresses at tile-mortar interface under various scenarios of mortar shrinkage and temperature cycles were calculated. Finally, the interfacial damage characteristics were system- atically studied in terms of three indices including damage degree, damage area and debonding area. Results showed that a larger shrinkage of mortar brought about a higher relative movement and stronger interfacial stress, thereby accelerating the propagation of interfacial damage from the rim to the center. In the case of considerably low mortar shrinkage, the interfacial relative deformations were too low to provoke any interfacial damage. The increases of temperature amplitudes promoted the accumulation and propagation of interfacial damage, causing an earlier appearance of debonding. The effects of cooling cycles were much greater than those of heating cycles. The damage degrees induced by cooling cycles were equivalent to those by mortar shrinkage in certain cases. Although considerably low shrinkage failed to initiate interfacial damage, its coupling with temperature cycles significantly aggravated interfacial damage, in particular for debonding area remarkably increased after 1000 cooling cycles.