Semnan University Press Journal of Transportation Infrastructure Engineering 2423-5350 7 2 2021 08 23 Effect of bacteria on self-healing of bio-concrete by increasing compressive strength Effect of bacteria on self-healing of bio-concrete by increasing compressive strength 41 50 5133 10.22075/jtie.2021.21387.1480 FA Abolfazl Noori Shahrabadi Faculty of Civil and Environmental Engineering, Semnan University, Semnan, iran Abolfazl Hassani Professor, Faculty of Civil and Environmental Engineering, Tarbiat Modarres University, Tehran, Iran Bita Bakhshi Professor, Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Journal Article 2020 09 30 Concrete is one of the most used materials in the world. Cracking in concrete is a common problem that occurs due to its relatively low tensile strength. The cracks created in concrete are the main reason for the reduced durability and useful life of concrete structures. Proper and timely repair of primary cracking is necessary in order to prevent its expansion in concrete and reduce the high cost of maintenance. For this purpose, self-healing methods have been developed. Adding microorganisms to concrete mixing and bio-concrete production is an intelligent and environmentally friendly strategy for the repair of concrete cracks. Bacterial species resistant to hard and rough concrete environment such as bacillus, with the production of calcium carbonate precipitation, can be repaired in a continuous hydration process by filling freshly formed fine cracks. The aim of this study was to identify the effective bacterial species and its effect on the strength properties of concrete as a restorative agent.The results show that the changes in the strength properties of bio-concrete by adding Bacillus subtelius at a concentration of 〖10〗^8 (Cells⁄ml), increase the compressive strength by 24.24% and also improve the durability of concrete by bacterial self-healing process. Concrete is one of the most used materials in the world. Cracking in concrete is a common problem that occurs due to its relatively low tensile strength. The cracks created in concrete are the main reason for the reduced durability and useful life of concrete structures. Proper and timely repair of primary cracking is necessary in order to prevent its expansion in concrete and reduce the high cost of maintenance. For this purpose, self-healing methods have been developed. Adding microorganisms to concrete mixing and bio-concrete production is an intelligent and environmentally friendly strategy for the repair of concrete cracks. Bacterial species resistant to hard and rough concrete environment such as bacillus, with the production of calcium carbonate precipitation, can be repaired in a continuous hydration process by filling freshly formed fine cracks. The aim of this study was to identify the effective bacterial species and its effect on the strength properties of concrete as a restorative agent.The results show that the changes in the strength properties of bio-concrete by adding Bacillus subtelius at a concentration of 〖10〗^8 (Cells⁄ml), increase the compressive strength by 24.24% and also improve the durability of concrete by bacterial self-healing process. https://jtie.semnan.ac.ir/article_5133_d6dd188ad22869c7bd350dfe04969cbd.pdf