A biomediated deterioration mitigation method for cement-treated soil

Cement-treated soil is widely used in many countries and is sometimes applied in estuary and coastal region civil infrastructures such as embankments and port facilities. In some of these facilities, leachates and deterioration of strength have been detected after 20 years of service and therefore require maintenance work such as chemical injection and reconstruction. The reasons for these failures could be the elution of calcium ions from calcium chloride (CaCl₂) in cement-treated soil. The main objective of the present research project was to propose biobased deterioration mitigation techniques that can independently recrystallise calcium ion eluates to calcite in cement-treated soil and thereby maintain operational conditions and long-term use of infrastructures. The mechanisms of calcite recrystallisation focused on microbial-induced calcite precipitation (MICP) under high pH conditions (pH ≈ 9·0), which was confirmed in laboratory tests. The main outcome of this research is that application of the MICP process to cement-treated soil can maintain operational conditions and can mitigate deterioration by simple addition of chemicals during the mixing phase.