Self-Healing Behaviors of Core–Shell-Structured Microcapsules Cement-Based Materials Immobilized with Microbes by Expanded Perlite

Abstract

To improve the weather resistance of Bacillus mucilaginous L3 in cement-based materials, we used the expanded perlite as an immobilization carrier of B. mucilaginous L3, and prepared core–shell-structured microcapsules using a metakaolin-sodium silicate mixed solution as the coating shell. Such immobilization by microcapsules can ensure the high weather resistance of B. mucilaginous L3 in cement-based materials, and was characterized by relevant methods. The cement-based materials containing self-healing microcapsules demonstrated high weather resistance, and can heal the largest cracks width of 0.85 mm. The expanded perlite offered the microbes with attachment sites and a survival and protection space. The self-healing grains coated with high-activity metakaolin can contact well with the substrate in the concrete, which showed excellent integrity. The minerals separated out by the self-healing microbes were high-purity calcite-like calcium carbonate and exhibited high healing ability.