水泥固化/稳定化场地污染土的效果分析

Performances of cement-stabilised/solidified contaminated site soils

针对目前原位固化/稳定化技术的长效性以及不同污染场地对固化/稳定化处理效果影响的不确定性,通过对比水泥-粉煤灰固化剂处理的污染土在不同固化剂配比下的强度、pH和重金属的浸出随时间的变化情况,研究对比了其在英国两个实际场地修复项目之间的处理效果。涉及的两个污染场地分别位于英国的密德萨斯地区和Castleford,Yorkshire地区,均不同程度地被重金属（Cu、Ni等）和有机物所污染。通过实测现场固化污染土不同时间点的无侧限抗压强度和两种标准（TCLP和BSEN 12457）下的浸出液污染物浓度,给出了两个项目中水泥-粉煤灰固化污染土的强度和pH随时间变化的曲线;计算得出了不同时间点Cu和Ni的固定效率。现场试验结果表明,两种重金属在所有水泥-粉煤灰固化污染土0.08~17 a间的时间点上的固定效率均超过99.4%;最后,通过比较两个项目中在不同时间点所测得的强度、浸出等数据,验证了水泥固化污染土在工程实例中长达17 a的有效性。

The effectiveness of cement-fly ash-treated contaminated soils in two remediation case studies in the UK is studied by comparing their time-related performances （e.g., strength, pH and leachate concentration of heavy metals）. This is because the long-term performances of in-situ stabilisation/solidification technology and the effects of this technology on different contaminated sites are uncertain. The sites involved in this research are the West Drayton in Middlesex and the Castleford, Yorkshire, each with a different range of organic and inorganic contaminants （Cu, Ni, etc.）. Field trial samples are subjected to unconfined compressive strength （UCS） and two batch leaching tests （TCLP and BSEN 12457） at different time points. The results detail the strength and pH relationship of similar mixes under different site conditions and different time scales, so as to validate the effectiveness of this remediation technique. The immobilization degrees of these two metals in different mixes under different time points （0.08-17 years） are calculated, the values of which are 〉99.4%. The 17 years＇ effectiveness of cement-fly ash-stabilised/solidified contaminated soils in these two case studies is confirmed by comparing their strengths and leachabilities at different curing time points.