Self-Healing Performance of Concrete with Combined Incorporation of CCCW and Microcapsules

Crack-induced durability deterioration remains a critical challenge for concrete structures. Cementitious capillary crystalline waterproofing materials (CCCW) enable moisture-driven crystallization, while alginate/epoxy microcapsules provide stress-induced bonding. However, it remains unclear whether combining the two agents produces a complementary repair effect or only an additive one under different humidity conditions. This study investigates the self-healing properties of concrete containing CCCW and alginate/epoxy microcapsules. The results indicate that the healing performance of microcapsules depends little on moisture dependence and shows stable repair performance, while CCCW performs well in humid environments but is inhibited under dry conditions. At a fixed total dosage of 3%, the optimal hybrid system containing 2% microcapsule and 1% CCCW achieves higher recovery rates than any single-admixture group under all three curing conditions. This improvement is consistent with potentially complementary contributions from microcapsules and CCCW, although the detailed chemical nature and temporal evolution of the observed deposits require further investigation. This study provides a reference for the design and application of multi-component self-healing concrete in complex service environments.