Insights into the effects of the clay minerals and porosity on the durability of clay bricks subjected to wetting-drying process

Clay brick is a widely used construction material in buildings. Considering the presence of clay minerals in the clay brick, it is susceptible to deterioration due to wetting-drying (WD) process. Deterioration can lead to adverse changes in the strength characteristics of a brick and consequently, a reduction in its load-bearing capacity and the possibility of structural damage to the building. In the present study, the durability of clay bricks against WD was evaluated by measuring their uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and point load index (PLI). For this purpose, specimens prepared from the bricks were subjected to 50 cycles of WD, and after every 10 cycles their UCS, BTS, and PLI were determined. The regression equations were established based on the UCS, BTS, and PLI data measured during the various WD cycles. The results indicate a significant loss in the UCS, BTS, and PLI with increasing WD cycles. According to visual inspection, loss in the UCS, BTS, and PLI was due to development of microcracks in the bricks during WD cycles. The rates of loss (RL) of UCS, BTS, and PLI after the WD process were strongly affected by the clay mineral content and porosity of the bricks. Finally, regression equations have acceptable performance in predicting the UCS, BTS, and PLI of bricks in various WD cycles. These equations can be used as practical, fast, and low-cost tools for a preliminary assessment of the durability of clay bricks subjected to WD process. The durability behavior of the clay bricks subjected to the wetting-drying A significant loss in the strength characteristics during the wetting-drying cycles Pore space modification of the bricks due to deteroration effects of wetting-drying The integrity loss in the bricks was affected by clay mineral content and porosity Good performance of the regression equations to predicte the strength characteristics