187 / 2022-04-30 22:01:24

Recent Advances in self-healing performance of Engineered/Strain-Hardening Cementitious Composite (ECC/SHCC)

Engineered Cementitious Composites,Strain-Hardening Cementitious Composites,Self-healing properties,Self-healing mechanism

Concrete is the most widely used construction material in modern engineering. Its durability and long-term performance are of great significance to the safety and longevity of infrastructures. However, concrete is a type of brittle material with very low tensile strength, and cracks may occur at any stage during the life cycle of a structure. Therefore, it is urgent to find a cementitious material with reliable crack control ability and self-healing potential. Engineered/Strain-Hardening Cementitious Composites (ECC/SHCC) are a class of advanced fiber-reinforced cementitious materials that can enhance the safety and longevity of structures. Benefiting from its excellent crack control ability and low water/binder ratio, the autogenous self-healing potential of ECC has attracted extensive attention. Many scholars have investigated the self-healing performance of ECC with different binder compositions, pre-load levels, and curing conditions.



The main self-healing mechanism of ECC is the continuous hydration of un-hydrated cementing materials and the formation of calcium carbonate (Fig.1). The short random fibers in ECC can provide nucleation sites for healing products, which can promote the crystal deposition and recovery of fiber-bridging capacities (Fig.2). The tight crack width is conducive to self-healing progress, and the abundant un-hydrated components in the matrix provide the material basis.



The self-healing properties of ECC under different service conditions are mainly affected by the moisture condition as well as the concentration of calcium and carbonate ions. The condition with wet-dry cycles shows the best healing effects (Fig.3), followed by the water curing and air curing conditions. Likewise, ECC also show reliable self-healing performance under natural environment (Fig.4). Moreover, ECC can maintain satisfactory self-healing performance under harsh ionic environments (Fig.5) and extreme temperatures. In addition, different supplementary cementitious materials have their own contributions to the self-healing capacity (Fig.6), while the curing age and loading conditions also affect the self-healing performance. 



This article tries to summarize some recent advances in the self-healing performance of ECC, with particular focus on the self-healing mechanism and some key affecting factors (i.e., crack width, humidity, temperature, ionic environment, binder composition, and curing age). We try to provide a reference for the material design and practical application of high-performance fiber-reinforced cementitious composites with self-healing properties.