Keywords

Abstract

Bacillus species;


Crack healing;


Cell concentration;


Flexural strength;


Ultra-sonic pulse velocity

The main aim of this investigation is to determine the influence of Bacillus species on the crack healing ability and flexural strength of concrete. In this regard, four bacillus species, such as "Bacillus halodurans (BH), Bacillus cereus (BC), Bacillus licheniformis (BL), and Bacillus subtilis (BS), and two bacterial cell concentrations are selected (viz., 108 and 109 cells/ml of water), and the concrete specimens are cracked with a 65% stress level concentration. To identify the crack healing ability of selected bacillus species, three different curing conditions are adopted: calcium lactate, water, and ambient curing conditions. The ultrasonic pulse velocity test (UPV) has been conducted to identify the crack healing ability of the selected bacillus species. From the results, calcium lactate-based cured concrete specimens showed better UPV values and crack healing ability. whereas Bacillus halodurans (BH) effectively filled the crack with calcite precipitation, which is the reason for 90% of crack healing ability and the high flexural strength recovery compared to other selected bacillus species. There is not much difference observed between the bacteria with cell concentrations of 109 and 108; however, 109 has a high healing ability and recovers flexural strength.

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