Relationship between tile exfoliation and moisture content

In Japan, tile exfoliation from external walls is a serious problem that must be prevented.In our previous study, a tiled concrete sample was dried at a temperature of 105 °C for pre-conditioning. Then, tile exfoliation occurred. Since this seemed to indicate a relationship between tile exfoliation and moisture content, it was further pursued in this study.First, drying experiments on concrete samples just after tiling were carried out under different ambient air temperatures. The following results were obtained.• Tile exfoliation occurs even at the lower drying temperatures. • Tile exfoliation starts at corner tiles (seen in all experiments). • When the average moisture content of the tiled concrete sample becomes lower than a certain value, tile exfoliation occurs.Next, the experiments were analyzed using a three-dimensional model of simultaneous heat and moisture transport. The calculated moisture content agreed well with the measured results. By comparing the measurement and simulation results, it is considered that the tiles are exfoliated when the moisture content of the mortar on the back side of the tile becomes lower than a certain value.Therefore, the moisture content can serve as an index for evaluating the occurrence of the tile exfoliation.