Author Description

Concrete is most predominantly used building material due to its high compressive strength and cheap availability of its components. However, the cracks in the concrete are inherent due its weak tensile nature and thus cannot be avoided whatever the grade of concrete is used. To repair the cracks at the initial stage, the concept of self-healing is used. In this research, silica gel immobilized bacteria “Bacillus sphearicus” has been used as self-healing agent. The bacterial specimens were kept under different curing conditions: wet-dry cycles and complete immersion. The samples were tested for strength re-gain, healing ratio, self-healing activity and water permeability. The test results showed that there was 70-80% strength regain under wet-dry cycles and crack widths up to 0.65mm were healed completely. The permeability of bacterial concrete samples showed a 20-25% reduction with 7.85x10-9 cm/second as coefficient of permeability compared to normal concrete having 9.9x10-9cm/second. The micro-structure analysis to determine the type and morphology of deposition material was carried through Scanning Electron Microscope (SEM), Electron Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD). The micro analysis showed the deposition material as calcite and peaks were obtained in XRD spectra.