Autogenous healing efficiency of calcium (OPC) and magnesium (MgO) binder-based strain-hardening cementitious composite (SHCC)

This study investigated the effects of hydrated phase composition [tailored using Portland cement (OPC) and reactive magnesia cement (RMC), water-to-binder (w/b) ratio, and curing age] on the autogenous self-healing behavior of strain-hardening cementitious composites (SHCC). The healing efficiency was characterized by stiffness recovery and crack width. The morphology of the cracked sections and chemical characterization of the matrix and healing products were carried out simultaneously to understand the characteristics of healing products and underlying mechanisms. The stiffness recovery reduced with increased curing age for OPC-based SHCCs, but the effect was insignificant in RMC-based SHCCs. The threshold crack width for complete healing was larger for OPC-based SHCCs than RMC-based SHCCs. A low w/b ratio is beneficial for robust self-healing in both OPC and RMC-based SHCCs due to increased unreacted cement content in the matrix. The possibility of early-age crack healing was higher in all the investigated SHCCs. The RMC-based SHCC with a low w/b ratio, maintained its autogenous healing capacity irrespective of the composite age.