Self-healing behavior of high-strength strain-hardening cement-based composites (HS-SHCC) blended with limestone calcined clay cement (LC3)

Self-healing is an important characteristic of cement-based composites, which is highly related to the safety and service life of construction materials under load and variable environmental conditions. This study investigated the self-healing behavior of ordinary Portland cement-(as Ref) and Limestone Calcined Clay Cement (LC3)-based high-strength, strain-hardening cement-based composites (HS-SHCC) under different exposure conditions. Experimental results showed that wet-dry cycles were favorable for crack healing in both Ref and LC3 HS-SHCC due to the abundant moisture for cement rehydration. However, the new-formed hydration products were weak and fiber bridging in HS-SHCC was not re-built. Thus, the healed pre-cracks were easy to crack again during re-loading. Between Ref and LC3 HS-SHCC, Ref composites showed a favorable self-healing behavior in terms of flexural strength improvement after wet-dry cycles, whereas LC3 composites presented desirable self-healing performance after freeze-thaw cycles due to the discrepancy in reaction products and microstructure. In sum-mary, Ref and LC3 HS-SHCC presented desirable but different self-healing performances under various exposure conditions.