Impact of ureolytic and nonureolytic bacteria on self healing of artificial cracks in biofortified concrete

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ABSTRACT

Two species of ureolytic bacteria (Bacillus sphaericus, Bacillus megaterium), and one non-ureolytic (Bacillus cohnii) were examined alone and in combination for their impact on crack repair and compressive strength in biofortified concrete. A combination of Bacillus cohnii and Bacillus megaterium achieved the maximum compressive strength (47.29 MPa) in 1 OD cells/ml after 28 days of curing in conventional 30 MPa strength of concrete. Further fly ash-blended (25%) concrete with Bacillus cohnii and Bacillus megateriume exhibited the compressive strength of 42.42 MPa at after 28 days of curing. The combination mix of Bacillus cohnii and Bacillus megaterium completely healed artificial cracks of 0.3 mm width by the formation of calcium carbonate. Further, XRD and SEM with EDS analysis confirmed that all three bacteria were able to make calcium carbonate precipitate in two phases of calcite and aragonite. The maximum amount of calcium carbonate mineral was deposited in the co-culture mix of bacteria Bacillus cohnii and Bacillus megaterium as confirmed by XRD test.

KEYWORDS:

• Biofortified concrete
• self healing
• ureolytic bacteria
• nonureolytic bacteria

Disclosure statement

No potential conflict of interest was reported by the author(s).