Effect of fly ash on the self-healing capability of cementitious materials with crystalline admixture under different conditions

The self-healing capability of cracks plays an important role in improving the durability of concrete. This study investigated the the self-healing capability of mortar with crystalline admixture and fly ash under three conditions. The compressive strength, water absorption, and surface crack pattern were used to evaluate self-healing capability of mortar, and the composition of the healing products was analyzed by x-ray diffraction and scanning electron microscopy. The results indicated that the crystalline admixture could improve the self-healing capability of cementitious materials but caused a negative effect if adding too great an amount of fly ash (≥20%). The specimen that was immersed in water showed favorable self-healing capability of cracks. The healing products in cracks are mainly composed of CaCO3