Experimental Study on Mass Stabilization of Soft Soil Foundation Based on MgO-CO₂ Carbonation Technology

Abstract

Mucky soft soil with weak properties was usually improved by the chemical stabilization owing to the high cost of the situ replacement, and the main chemical binder used was Portland cement (PC). However, with the needs of environmental protection, energy conservation and emissions reduction, the research of low-carbon and high-efficiency soft soil treatment technology will be the development trend of modern engineering construction. The combined binder of reactive magnesia (MgO) and carbon dioxide (CO₂) was regarded as a new curing agent instead of traditional PC, and the mass carbonation technology as an innovative idea was put forward to reinforce soft soil. In this view, the field mass stabilization was carried out and the single-point test was analyzed. Research results show that the temperature from the carbonation reaction is higher than that from the hydration reaction, and the temperature, strength and carbonation degree of the upper foundation soils increase significantly compared with the lower foundation soils, while the water content and pH value of the upper foundation soils are less than those of the lower foundation soils; the smaller the distance from the CO₂ gas supply is, the higher the carbonation temperature, resilience modulus, penetration resistance, strength and carbonation degree are; the pipe-cover mass carbonation–stabilization technology can realize the carbonation and reinforcement of the on-site weak soils, but it should be noted that the CO₂ should be injected at the bottom. The maximum ventilation radius should be 60 cm and the distance between the CO₂ pipes should be less than 1.2 m in practical application. The bearing capacities of all regions are above 200 kPa, and the resilient moduli are about 20 MPa. The experimental research of mass stabilization based on MgO-CO₂ carbonation technology has groundbreaking scientific significance and application prospects in the emission reduction and sustainable development of civil engineering.