A full-depth self-healing strategy for cracks in cement-based materials under marine environment

The depth of crack self-healing is crucial in advancing self-healing technology in cement-based materials. An additional challenge arises in marine environments with the infiltration of corrosion ions into the cracks. A self-healing approach revolving around microbial mineralization and layered double metal hydroxides (LDHs) is proposed to address these dual challenges. The findings demonstrate a significant enhancement in the healing properties of the mortar when mixed with the healing agent, particularly in terms of ultrasonic speed and resistance to cross-cracking, which are indicative of internal self-healing effects. The depth of crack self-healing was greatly improved, with a wide distribution of healing products observed on the crack surface. This healing effect is attributed to the in-situ formation of LDHs within the cracks. LDHs immobilizes a substantial amount of hydroxide ions, chloride ions, sulfate ions, and water molecules, resulting in improved volume expansion performance and effective sealing of the cracks. Moreover, the physical and chemical conditions within the crack solution were optimized, enhancing the activity of microorganisms and thereby improving the healing rate of the crack opening area. This multi-modal synergy-based self-healing strategy holds promise as a potential solution for achieving efficient crack self-healing.