Nanomechanical Characterization of Enzyme Induced Carbonate Precipitates

The mechanical properties of calcium carbonate minerals formed by enzyme-induced precipitation (EICP) were studied using nanoindentation. Two types precipitates considered: (i) a “baseline” precipitate, synthesized via urea hydrolysis in an aqueous solution urease enzyme, urea, and chloride; (ii) “modified” from similar solution, but with the inclusion nonfat dry milk. While both predominantly comprised calcite, X-ray diffraction Raman spectroscopy indicated broader peaks modified implying differences crystal structure two precipitates. Both polycrystalline had higher average indentation hardness (H) lower modulus (M) compared values for single calcite crystals reported literature. ductility was quantified ratio M/H. precipitate M/H, greater ductility. increased results resistance to crack propagation. In sands biocemented EICP addition preferential at interparticle contacts, may contribute relatively high unconfined compressive strengths low contents.