Permeable rock matrix sealed with microbially-induced calcium carbonate precipitation: Evolutions of mechanical behaviors and associated microstructure

Microbially-induced calcium carbonate precipitation (MICP) is a promising grouting material for subsurface remediation due to its water-like viscosity and excellent penetration. Current studies of MICP-grouting both rock fractures highly-permeable matrix focus on the spatio-temporal distribution precipitated bio-CaCO3 resulting reduction in permeability. Conversely, we improvement mechanical response following MICP-grouting. We contrast improved MICP-treated Berea sandstones with distinctly contrasting initial properties - associated pre- post-treatment microstructures various durations Results indicate that although CaCO3 mass time within these two types similar, significant differences exist evolution (UCS, Young's modulus brittleness). The low-strength sandstone (initial UCS 25.7 MPa) exhibits three phases: an slow increase, followed by rapid-increase then saturation asympotic response. After ten cycles MICP-grouting, UCS, elastic brittleness index increase 229%, 179% 177% compared before grouting. In contrast, high-strength 65.1 are not significantly enhanced, increasing only 22%, 14% 12%. Imaging scanning electron microscopy (SEM) indicates cementing minerals fill quartz framework but sparse sandstone. Sandstone clastic sedimentary consisting grains bonded minerals. For infused large minerals, crystals precipitate gaps between or adhere This capable relatively limited enhancement bio-bonding strength volume framework. fewer evenly distributed surfaces gains. bulk progressively increased ongoing bio-cementation Cementing mineral contents exert considerable control integral penetration sandstone, also have direct influence microscopic bio-accumulated CaCO3, controlling effectiveness incrementing properties.