Cracks Repairing and Resistance to Water Penetration Properties of Microbial Self‐Healing Cement

This study focuses on applying microbial self-healing cement in repairing cracks in cement-based materials and enhancing its resistance to water penetration performance. Traditional cement is susceptible to environmental influences, leading to the formation of microcracks and a reduction in durability. This research used <i>Bacillus pseudofirmus</i> to prepare microcapsules through sodium alginate gelation technology. We mixed microcapsules into the cement. The results indicate that the microbial self-healing cement, with a 1% self-healing agent added, increased its resistance to water penetration ability by 29.2% after 28 days. This improvement rose to 39.3% after 84 days. Additionally, we used the embedded needle method to make mortar blocks through microcracks, mimicking the cracks found in real cement. The self-healing effect of the microcapsules was especially noticeable for cracks under 0.3 mm in diameter, compared to the commonly used commercial crystallization penetration technology. This is attributed to the crystalline bodies formed by the self-healing agent in the microcapsules blocking the cracks and preventing water penetration. This study provides an environmentally friendly solution for the repair of cracks in cement-based materials using microbial self-healing technology and lays the foundation for improving the repair efficiency and durability and exploring stability and reliability in the future. <i>Practical Application:</i> This study investigated the application of microbial self-healing cement in repairing cracks in cement-based materials and enhancing its resistance to water penetration properties. Cement, a material widely used in infrastructure, has low tensile strength and often forms microcracks. These microcracks reducing the durability of cement and posing risks to the economy and safety. Adding 1% self-healing agent to microbial self-healing cement significantly increases the resistance to water penetration pressure of the mortar blocks. Compared to the standard specimens, the resistance to water penetration ability increased by 29.2% at 28 days and further increased to 39.3% at 84 days. Microbial self-healing cement could effectively restore the resistance to water penetration performance of the mortar blocks after repairing cracks. The repairing results are significantly better than the methods of mixing or applying cement crystalline materials.