Self-healing recovery and micro-structural properties of slag/fly-ash based engineered cementitious composites under chloride environment and tidal exposure

Self-healing behavior of Engineering Cementitious Composites (ECC) has received a lot of attention due to its influence on the durability and mechanical performance of composite structures exposed to marine environment. However, very few studies have reported mechanical recovery of self-healing ECC under marine environmental exposure conditions. This paper reportes an experimental study of self-healing induced mechanical recovery of pre-damaged slag/fly ash based ECC and chloride transport behavior in ECC exposed to simulated marine environmental for up to 120 days. The results show obvious regaining of tensile properties of pre-damaged slag/fly ash based ECC due to self-healing. At the micro-scale level, the presence of abundance fly ash particles facilitates the stress transfer between the fiber and the matrix after self-healing, leading to fiber-bridging strength recovery to roughly the same level as that of the control specimen. Furthermore, the ultimate tensile strength shows a slight recovery for all ECC specimens under tidal and submerged environmental conditions, as compared to the 28-day result. However, as the slag replacement level increases, some inconsistencies emerge. Because of high chloride content and oxygen content, as well as the action of tidal impact, concrete deterioration and corrosion are more intense in tidal and splash zones . • The presence of microcracks in the composite matrix is related to the resistance of hydration products and PE fiber to external stress. • The compressive strength of ECC increases with the increase in seawater exposure. • The ultimate tensile strength shows a slight strength recovery for all specimens under both environmental conditions.