Characterization and Applications of Biocement Enchanced with Carbon Nanotubes for Improved Remediation on Cracked Concrete Structures

Abstract

A bacterial bio-sealant known as calcite is used to seal cracks and holes in buildings and monuments. We have attempted to enhance the production and application of carbon nano tubes with biosealant from Bacillus sphaericus with concrete cubes using mix design for the target compressive strength of 50 MPa by response surface methodology. The optimized media was further optimized for pH and nickel concentrations. The column designed for calcite production was packed with mixture of fine Norris sand, fly ash, urea, CaCl₂ and the immobilized bacterial species Bacillus sphaericus. After 7 days of a production cycle, the fly ash mixture containing CaCO₃ was applied to artificially induced cracked cubes. The cubes were examined for the variation in their compressive strength at 50 MPa and inferred that compressive strength of calcite applied cubes showed increase in strength compared with cement mortar application. Biocaulk with different ratios of carbon nano tubes such as 2, 4 and 8 g, respectively to improve the increase in strength was determined. Our results showed the strength was further strengthened to 37.5 % by adding 20 % of carbon nano tubes to the total sealant.