Semnan University Press Journal of Transportation Infrastructure Engineering 2423-5350 10 3 2024 11 21 Investigating and Comparing the Mechanical Resistance of Bacterial Self-healing Concretes Investigating and Comparing the Mechanical Resistance of Bacterial Self-healing Concretes 37 51 9079 10.22075/jtie.2024.34979.1682 FA Abolfazl Noori Shahr Abadi PhD Candidate of Road and Transportation, Faculty of Civil Engineering, Semnan University, Semnan, I.R. Iran. Gholamali Shafabakhsh Professor, Department of Road and Transportation, Faculty of Civil Engineering, Semnan University, Semnan, I.R. Iran. Bita Bakhshi Professor Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Journal Article 2024 08 07 Cracks are one of the main causes of concrete failure, facilitating the penetration of chemical solutions and negatively impacting the characteristics of concrete structures. To address this problem, various methods such as coatings and adhesives have been used. However, due to the high costs and issues like peeling, attention has shifted toward alternative methods, including self-healing concrete. One of these methods involves the use of microorganisms to repair cracks. In this study, Bacillus subtilis bacteria were used, which, unlike other bacteria, do not require microcapsules or nanomaterials, making it less expensive to produce. The use of this bacteria has significantly improved the compressive, flexural, and tensile strength of the concrete. The RB10 and RB12 samples showed the highest strength increases, with RB10 exhibiting a 100% increase in flexural strength and 76.5% in compressive strength. Additionally, the tensile strength of the concrete increased by up to 15% with the use of this bacteria. Cracks are one of the main causes of concrete failure, facilitating the penetration of chemical solutions and negatively impacting the characteristics of concrete structures. To address this problem, various methods such as coatings and adhesives have been used. However, due to the high costs and issues like peeling, attention has shifted toward alternative methods, including self-healing concrete. One of these methods involves the use of microorganisms to repair cracks. In this study, Bacillus subtilis bacteria were used, which, unlike other bacteria, do not require microcapsules or nanomaterials, making it less expensive to produce. The use of this bacteria has significantly improved the compressive, flexural, and tensile strength of the concrete. The RB10 and RB12 samples showed the highest strength increases, with RB10 exhibiting a 100% increase in flexural strength and 76.5% in compressive strength. Additionally, the tensile strength of the concrete increased by up to 15% with the use of this bacteria. https://jtie.semnan.ac.ir/article_9079_3bce7df15ef880d1d0f343c86dc061e3.pdf