Factors Affecting the Improvement of Sand Properties Treated with Microbially-Induced Calcite Precipitation: Fid-Bau Portal

Factors Affecting the Improvement of Sand Properties Treated with Microbially-Induced Calcite Precipitation

Amarakoon, G. G. N. N. / Kawasaki, S.

Bio-mineralization is an environment-friendly technology to improve soil engineering properties. One of common bio-mineralization processes is microbially induced calcite precipitation (MICP). A series of laboratory tests was conducted to produce solidification of the specimen having an estimated unconfined compressive strength (UCS) of more than several MPa, and investigate the influence of varies factors on soil properties treated with MICP. A solidification test was conducted using a syringe (30 mL) on different particle size of Mikawa sand (mean diameter: 0.6mm) and Toyoura sand (mean diameter: 0.2mm) using local ureolytic bacteria: Parahadobactor sp. isolated in Japan. The bacteria were grown up for 72 hours to increase the optical density (OD) of 600 nm (OD₆₀₀). The cementation media was added and the solidification test was conducted until 14 days. After that, needle penetration tests were conducted to obtain the estimated UCS value of the specimen. The results indicated that the estimated UCS value was exceeded 3 MPa for three Mikawa sand samples: (1) sample treated by 1.0g of bacteria re-injected bacterial solution after 7 days, (2) sample treated by 1.0g of bacteria without re-injection after 7 days, and (3) sample treated with 0.1g of bacteria with re-injection.