Strength Characteristics of Peat Stabilized with Enzyme-Induced Carbonate Precipitation and Inorganic Binders

Postconstruction problems—such as low foundation strength, postconstruction settlement, and extended settlement durations—must be addressed when building structures on peat foundations. In previous engineering practice, inorganic binders were used primarily to stabilize peat foundations. However, peat stabilized with inorganic binders exhibits relatively low strength and can result in substantial carbon emissions. Peat from the Dali region of the Yunnan Province was investigated in this study. Unconfined compressive strength (UCS) and calcium carbonate precipitation rate tests were conducted to examine the changes in UCS. The study focused on combining the environmentally friendly enzyme-induced carbonate precipitation (EICP) technique with various proportions of cement, gypsum, fly ash, and sand. The results were compared with the strength characteristics of peat stabilized using EICP alone or inorganic binders (such as cement, gypsum, and fly ash). The results showed that the combination of EICP with inorganic binders improved the UCS of stabilized peat considerably, with varying degrees of strength enhancement depending on the binder used. The combination of EICP with 10% (142 kg/m3) cement achieved the best results, yielding a UCS 12.5 times higher than that of peat stabilized with 10% (142 kg/m3) cement alone and 2.6 times higher than that of peat stabilized with EICP alone. The addition of sand was found to inhibit the strength development of stabilized peat. The calcium carbonate precipitation rate of peat stabilized using the EICP–inorganic binder combination was considerably higher than that of peat stabilized with EICP alone, indicating that inorganic binders could promote the urease reaction to generate calcium carbonate, thereby enhancing the strength of the stabilized peat. This study confirmed the superiority and feasibility of combining EICP with inorganic binders for peat stabilization, offering a new method for practical engineering applications in the field.