An experimental study on effect of Bacillus sphaericus bacteria in crack filling and strength enhancement of concrete

Abstract

Abstract Objective of the present investigation is to develop a durable cement concrete by incorporating varying proportions of Bacillus Sphaericus bacteria in crack filling and strength enhancement through biomineralisation. Test samples were tested at different ages for cube compressive strength, split tension, flexural strength, modulus of elasticity and also for durability tests with Bacillus Sphaericus bacteria concentrations of 1000, 100,000, 107 cells per 1 ml, then verified by the reference test samples made without bacteria. The crack filling ability of bacteria are studied and found that at all the concentrations, the percentage loss of strength for cracked concrete specimen with bacteria was low compared to cracked concrete specimen without bacteria. For bacterial dosage of 100,000 cells/ml better results were noticed for strength and crack filling of specimens. But with further increasing the dosage of bacteria, the mechanical properties were decreased. Findings revealed that concrete with Bacillus sphaericus is much efficient for increasing the durability of concrete as percentage loss of compressive strength is low when exposed to acid attack. The development in the parameters tested for concrete with bacteria can be attributed to the precipitation of calcium carbonate which was found in SEM analysis. Incorporated bacterium into the concrete mixture do not harm in any way. Hence, it can be stated that the amalgamation of bacterium in concrete reduces the cracks there by adds durability to the concrete.