Use of bacteria to repair cracks in concrete
ABSTRACT As synthetic polymers, currently used for concrete repair, may be harmful to the environment, the use of a biological repair technique is investigated in this study. Ureolytic bacteria such as Bacillus sphaericus are able to precipitate CaCO3 in their micro-environment by conversion of urea into ammonium and carbonate. The bacterial degradation of urea locally increases the pH and promotes the microbial deposition of carbonate as calcium carbonate in a calcium rich environment. These precipitated crystals can thus fill the cracks. The crack healing potential of bacteria and traditional repair techniques are compared in this research by means of water permeability tests, ultrasound transmission measurements and visual examination. Thermogravimetric analysis showed that bacteria were able to precipitate CaCO3 crystals inside the cracks. It was seen that pure bacteria cultures were not able to bridge the cracks. However, when bacteria were protected in silica gel, cracks were filled completely.
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ABSTRACT: An organic acid material, which can be manufactured by plants extraction, encourages microbe proliferation over time. Microbial activity, which is affected by organic acid, encourages accelerating consolidation with biochemical penetration; soil particles are compacted by microbes and pore water is dissipated quickly. Additionally, for cementation was made by proliferating microbes. Accordingly, tests were conducted to investigate the unconfined compressive strength and permeability of soil samples aged with and without an organic acid. In the 96 days of aging, the strength was generally 1.5~2.5 times greater than those without an organic acid material and permeability was definitely decreased to 74.2~93.1%. SEM analysis showed the change of pore structure and the change of the total bacteria counts revealed the activity of microbes reflecting the engineering characteristics and this material would be an environment-friendly for soil improvement.Journal of the Korean Geotechnical Society. 01/2013; 29(2).
- Journal of Structural Engineering. 01/2011;
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ABSTRACT: Biological self-healing concrete is a new idea to have concrete structures with more durability. Although, several papers have been published on biological self-healing concrete, a suitable instruction to conduct this type of studies is not reported. Aim of this paper is collecting comprehensive information about conducting a study on self-healing concretes based on previous studies. This paper present many new ideas that have not been completely study. Some idea such as application of fungi, thermopiles bacteria, mix culture of microorganisms or using of aerobic or anaerobic bacteria to design biological self-healing concrete are suggested in this paper. Ideas of this paper can help researchers to find a suitable and novel subject in biological self-healing area to conduct a strong research.Journal of Environmental Treatment Techniques. 01/2013; 1(2):62-68.