Bio-cementation through controlled dissolution and recrystallization of calcium carbonate

We present an approach to bio-cementation of sand where the calcium source is prepared by dissolving powdered limestone (chalk) in lactic acid. Cementation is achieved through enzyme induced carbonate precipitation (EICP) with Jack Bean urease. The real-time nucleation and growth of crystals, crystal morphology and mechanical strength of consolidated samples was studied for dissolved chalk solution as well as calcium chloride (CaCl2) and calcium lactate solutions. Solutions containing lactate were found to yield spherical calcite crystals. The compressive strengths of consolidated samples ranged from 0.06 to 2.8 MPa, increasing with the amount of precipitated CaCO3.