固化铅污染土的干湿循环耐久性试验研究

Experimental research on durability of solidified lead-contaminated soils under wetting-drying cycles

在商用高岭土、膨润土与商业黄砂混合物中加入硝酸铅溶液,添加水泥和石灰两种固化剂,采用室内压实制样方法获得固化的铅污染土试样。进行干、湿循环试验,测试固化体的质量损失和无侧限抗压强度等参数随干、湿循环次数的变化规律,评价固化铅污染土的干、湿耐久性。测试结果表明,本试验8种配比的试样都满足干、湿循环的要求;黏土矿物为膨润土的试样干、湿循环耐久性比黏土矿物为高岭土的试样要差;水泥固化土的干、湿循环耐久性要略优于石灰固化土;加入8 000 mg/kg的铅可略增大土体的抗干、湿循环耐久性。水泥和石灰固化/稳定化重金属污染土时。

Kaolin and bentonite, two clay minerals are mixed with sand respectively, and then mixed with lead nitrate to produce artificial lead-contaminated soils. Cement and lime are used to solidify the artificial lead-contaminated soils respectively. The samples are made using the compaction method. The relative mass loss, cumulative mass loss rate and unconfined compression strength （UCS） of samples after wetting-drying cycle tests are recorded, in order to evaluate the wetting-drying cycles durability of the solidified lead-contaminated soil. The results show that the wetting-drying cycles durability of samples in this study all meet the requirement; wetting-drying cycles durability of bentonite mixed soil is worse than kaolin mixed soil; cement solidified soil performs better than lime solidified soil in terms of wetting-drying cycles durability; admixing 8 000 mg/kg lead slightly leads to an enhancement of wetting-drying durability of stabilized soils. Water content is a key parameter to immobilize heavy metal in cement or lime, and enough water should be available for hydration, hydrolysis, pozzolanic and carbonization reactions of cement or lime.