DEVELOPMENT OF COMPRESSIVE STRENGTH AND ULTRASONIC PULSE VELOCITY RELATIONSHIP OF MICROBIAL CONCRETE USING BACILLUS SUBTILIS BACTERIA

Concrete,a multiscale composite in its natural state, is an absolutely essential element of infrastructure throughout the world. Concrete is able to carry high compressive load but very weak in case of tensile forces, for which steel bars are embedded in the concrete.Again, cracks in concrete are unavoidable. Corrosive elements can go into cracks once theyve formed and consequently deterioration of the structural concrete starts with the corrosion of embedded steel. This leads to the strength reductionand durability curtailment of concrete. So, crack minimization in reinforced concrete is a must for both strength and durability aspect as well as for economic reasons as crack repair is a costly process. The goal of this study is to compare the performance of traditional and bacterial concrete and to find a link between compressive strength and bacterial culture concentration, as well as to determine the optimal bacterial concentration in concrete. 100 mm cubical sizeconcrete specimens were cast and cured for different ages in plain water to study the strength aspect and ultrasonic pulse velocity (UPV) analysis of concrete using Bacillus subtilis bacteria.With different bacterial concentrations of 2.12 x 108 cells/ml, 2.12 x 107 cells/ml, 3.25 x 108 cells/ml, 3.25 x 107 cells/ml, 6.39 x 108 cells/ml, 6.39 x 107 cells/ml, 7.91 x 108 cells/ml and 7.91 x 107 cells/mlconcrete specimens have been studied. From the investigation it is found that concrete specimens containing bacterial species shows better performance than conventional concrete due to calcite precipitation. Among them, concrete specimens of bacterial concentration 6.39 x 108 cells/ml of bacterial water shows better result against strength deterioration and UPV analysis.