EXPERIMENTAL STUDY ON BACTERIAL RICE HUSK ASH CONCRETE BY INCORPORATING QUARRY DUST AS PARTIAL REPLACEMENT OF FINE AGGREGATE

Cracks in concrete leads to the seepage of salts and water causing damage to the structure. So there is a need to use microbial material which self heals the cracks present in the concrete. In the present study, bacillus subtilis was used as a microbial material for the preparation of bacterial concrete. Control concrete was prepared for comparison with bacterial concrete. Rice husk ash (RHA) and Quarry dust (QD) are used as a partial replacement of cement and fine aggregate in both control concrete and bacterial concrete. Cement was partially replaced with 5%, 10%, 15% RHA and fine aggregate was replaced with 45% QD. Bacillus subtilis was added in the amount of 105 cells/ml during the mixing of bacterial concrete. Bacillus subtilis releases calcium precipitate which combines with carbonates present in the concrete and forms calcium carbonate which fills up the internal voids present in the concrete. Tests were performed to determine the compressive strength, split tensile strength and flexural strength for 3,7 and 28 days. It is observed that bacterial concrete shows higher strength compared to control concrete due to internal filling of voids by calcium carbonate. Concrete with RHA and QD shows little less strength than the control concrete due to its less workability