Document Type : Original Article
Authors
1
Construction Engineering Department, Faulty of Engineering, Egyptian Russian University Badr City, Cairo 11829, Egypt.
2
Engineering Construction Dept. Faulty of Engineering, Egyptian Russian University Badr City, Egypt Postdoctoral Fellow, Civil and Environmental Engineering Dept., University of Missouri, United States.
3
Associate Professor, Civil Engineering Department, Faculty of Engineering, Helwan University, Al- Mattaria Branch.
4
Housing and Building National Research Center, Cairo, Egypt.
5
Microbial biotechnology department- biotechnology research institute- national research centre
6
Construction Engineering Department, Faculty of Engineering, Egyptian Russian University/President of the Egyp-tian Russian University, Badr City, Cairo-Suez Road, 11829, Cairo, Egypt
Abstract
The study investigates the impact of various microorganisms on concrete properties, focusing on enhancing compressive and tensile strength through microbial activity. A total of 48 bacterial and fungal isolates were sourced from soil samples in Egypt's El-Sharkia governorate, cultured, and identified using morphological and biochemical techniques. Concrete specimens were prepared in two phases: the first involved adding six microbial samples at 3% of the cement content, while the second phase tested selected microorganisms at 5%, 10%, and 15% concentrations. The research aims to explore microbial-induced calcium carbonate precipitation (MICP) as an innovative method for enhancing concrete performance. Concrete mixes were prepared using the British "DOE" method with varying proportions of microorganisms, particularly Bacillus subtilis and Aspergillus fumigatus, to assess their effects on mechanical properties. Compressive strength was evaluated over 7, 28, and 56 days. Bacillus subtilis-treated samples showed a 13.9% increase in compressive strength (29.83 MPa) compared to the control (26.23 MPa), while Aspergillus fumigatus-treated samples exhibited a 14.3% increase (29.96 MPa). Tensile strength tests revealed improvements of 12.8% and 21.1% for Bacillus subtilis and Aspergillus fumigatus samples, respectively, compared to the control. Scanning electron microscopy (SEM) analysis confirmed that Bacillus subtilis significantly enhanced calcium carbonate precipitation, improving pore-filling and crack-healing properties. These findings highlight the potential of MICP in advancing concrete technology, offering a promising approach to improving concrete's durability and structural integrity.
Keywords
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