Author : Dr.Sadath Ali Khan Zai 1
Date of Publication :7th August 2016
Abstract: In reviewing technology advances through the centuries, it is evident that material development plays a key role, considerable efforts are still being made in every part of world to develop new construction materials, In the construction industry, concrete technology is heading towards entirely new era by way of using self healing bacterial concrete. Self-Healing Bacterial Concrete refers to a new generation of concrete in which selective cementation of porous media by microbiologically induced CaCO3 has been introduced for remediation of damaged structural formation or micro cracks. Which includes some widespread possibilities to close cracks in a cementations material, since strength and ductility are the two major important factors to be considered in the design of R.C.C structures? The main focus of the present research investigation is to obtain the performance of the concrete by the microbiologically induced special growth/filler. where bacteria is induced in the concrete to heal up the faults / cracks by using the bacteria Bacillus subtilis strain No.JC3. Calcite formation by Bacillus subtilis JC3 is a laboratory bacterium, which can produce calcite which precipitates on suitable media supplemented with a calcium source. The culture of bacteria from the soil sample at Microbiology and Biotechnology laboratories of Bangalore University, Bangalore and is maintained constantly on nutrient agar slants. A series of 150 mm cube specimen with design mix of M20 grade of concrete were casted by adding bacteria having 104 , 105 ,106 ,107 cells/ml-media of concentration for the optimization. The study showed a significant increase in the compressive strength due to the addition of bacteria for a cell concentration of 105 cells per ml . The investigation further extended to study the flexural behaviour of self healing bacterial reinforced concrete. A three point bending test is carried out on three test beam specimens with dimension 150mmx230mm and an effective length of 2200mm to obtain load deflection characteristics. By summarizing experimental results, it is observed that addition Bacillus subtilis JC3 ensures structural integrity in enhancement of ductility and energy absorption capabilities, this is due to the bio-mineralization of calcium carbonate in the concrete. Also Characterization studies were performed to confirm the calcite precipitation through X-ray Diffraction and Scanning Electron Microscope.
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