Calcite precipitation induced by polyurethane-immobilized Bacillus pasteurii

Polyurethane (PU) foam was used to immobilize the whole cell of Bacillus pasteurii. The immobilized cells exhibited the rates of calcite precipitation and ammonia production as high as those of the free cells. Scanning electron micrographs identified the cells embedded in calcite crystals throughout PU matrices. Calcite in PU showed little effect on the elastic modulus and tensile strength of the polymer, but increased the compressive strengths of concrete cubes, whose cracks were remediated with PU-immobilized cells. These observations led us to believe that the calcite might remain as a form of precipitation, not as a bonding material within the matrices.