The engineering characteristics of remediated soil are easily affected by CO₂ erosion in nature. However, there are limited investigations on the mechanical and microscopic properties of heavy metal-contaminated soil. This study introduces effect of accelerated carbonization on the mechanical and microscopic properties of nickel–copper-contaminated soil, and the soil has been treated with a novel curing agent, formed by mixing cement, fly ash and desulfurization gypsum (CFG). The objective of the study is to ascertain CO₂ erosion resistance of nickel–copper-contaminated soil solidified by CFG. Using unconfined compressive strength (UCS) tests, carbonization depth, X-ray diffraction, and scanning electron microscopy, the sample’s characteristics are investigated under different carbonization times and heavy metal ion concentrations. The results demonstrate that the UCS of samples of Ni0Cu0, Ni0.02, and Ni0.4 decrease with the increasing carbonization time, while that of Ni1, Cu1, and Ni1Cu1 increase initially and then decrease; in addition, when the concentration of heavy metals is lower, the effect of carbonization on UCS of samples is more significant. Moreover, the carbonization depth of samples increases with the increasing carbonization time, and the prediction model is given. Furthermore, the microscopic analysis demonstrates that calcium carbonate is the main carbonization product. The decomposition of hydrated calcium silicate gel leads to poor integrity of the structure and more pores produced in samples, which is the main reason for the decrease of the UCS in the process of carbonization. The outcomes of this investigation provide a reference for the durability in practical engineering of heavy metal-contaminated soil solidified by CFG.

修复土壤的工程特性很容易受到自然界中CO ₂侵蚀的影响。然而，对重金属污染土壤的力学和微观特性的研究有限。本研究介绍了加速碳化对镍铜污染土壤力学和微观特性的影响，土壤已用一种新型固化剂处理，该固化剂由水泥、粉煤灰和脱硫石膏 (CFG) 混合而成。该研究的目的是确定 CO ₂CFG固化的镍铜污染土壤的抗侵蚀性。使用无侧限抗压强度（UCS）测试、碳化深度、X射线衍射和扫描电子显微镜，研究了样品在不同碳化时间和重金属离子浓度下的特性。结果表明，Ni0Cu0、Ni0.02和Ni0.4样品的UCS随着碳化时间的增加而降低，而Ni1、Cu1和Ni1Cu1的UCS先升高后降低；此外，当重金属浓度较低时，碳化对样品UCS的影响更为显着。此外，样品的碳化深度随着碳化时间的增加而增加，并给出了预测模型。此外，显微分析表明碳酸钙是主要的碳化产物。水合硅酸钙凝胶的分解导致结构完整性差，样品产生更多的孔隙，这是碳化过程中UCS降低的主要原因。研究结果为CFG固化重金属污染土壤在实际工程中的耐久性提供参考。