Multiscale synergistic self-healing of ECC by curing film-assisted Ca(OH)₂ supply and crystalline admixture

Self-healing of engineered cementitious composites (ECC) is restricted under water-deficient exposure. This study proposes a self-healing curing strategy using a CF (CF) as a water-ion carrier, combined with Ca(OH)₂ (CH) solution and crystalline admixture (CA). The strategy was evaluated at both material and structural scales. Material-scale tests included water permeability, crack healing, and self-healing products analysis for ECC with various CA dosages under different curing regimes. The results indicate that CF imparts better crack self-healing and impermeability recovery than immersion curing, particularly combined with CH solution. With 8% CA, the CF pre-absorbed CH solution reduced the normalized permeability coefficient of ECC by 72.32% compared to water immersion, while the crack area healing ratio reached the highest value. At the structural scale, accelerated corrosion tests on cracked RC/ECC beams showed the combined use of CF and CH solution reduced the corrosion rate by 55.96% and the chloride content at 0–5 mm depth by 54.05%, with a crack area healing ratio of 87.24% for beams with 8% CA, relative to unhealed specimens. The consistent improvements at both material and structural scales confirms that the proposed self-healing curing system including a CF combined with CH solution and high-dosage CA can construct a suitable water-ion environment, providing a practical approach to solving the self-healing challenges of concrete structures in water-deficient conditions.