Strength and electrical conductivity characteristics of zinc contaminated soil carbonated/stabilized with GGBS-reactive MgO
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摘要: 采用工业废弃物粒化高炉矿渣（GGBS）-活性氧化镁（MgO）复合固化剂对锌（Zn）污染土进行碳化/稳定化处理,开展了碳化/稳定化Zn污染土的无侧限抗压试验和电导率测试试验,并与自然养护28 d的未碳化Zn污染土进行对比。研究了Zn2+浓度、固化剂掺和比对碳化/稳定化Zn污染土的无侧限抗压强度（qu）和孔隙液电导率特性的影响规律。试验结果表明：①当固化剂掺和比一定时,碳化固化Zn污染土的qu随Zn2+浓度的增加呈现先上升后降低趋势,而电导率呈持续上升趋势；②当Zn2+浓度一定时,碳化固化土的qu随复合固化剂中活性MgO含量的提高而上升,但其电导率却略有下降；③与自然养护28 d的未碳化Zn污染土相比,碳化后Zn污染土的qu更高,但电导率几乎不变。研究成果为工业废弃物和二氧化碳的再利用及其在重金属Zn污染土的绿色处理提供了新途径,对加速“碳达峰”具有重要的理论意义。Abstract: In this study, the compound binder of ground granulated blast furnace slag (GGBS)-reactive MgO is used for the carbonization/stabilization treatment of zinc (Zn)-contaminated soil. The unconfined compression and electrical conductivity tests on the carbonated/stabilized Zn-contaminated soil are conducted, and the uncarbonated Zn-contaminated soil after 28-day standard curing is used for comparison. The effects of Zn-ion concentration and binder mixing ratio on the unconfined compressive strength (qu) of the carbonated/stabilized soils and the conductivity of the pore fluid are investigated. The test results indicate that: (1) When the mixing ratio of curing agent is fixed, the qu of the carbonated Zn- contaminated soil first increases and then decreases with the increase of Zn ion concentration, while the conductivity increases. (2) When the content of Zn-ion concentration is fixed, the qu of the carbonated Zn-contaminated soil increases with the increase of reactive MgO content in the binder, but its conductivity decreases slightly. (3) The qu of the carbonated zinc contaminated soil is higher compared with that of the noncarbonated Zn- contaminated soil (28-day standard curing), but the conductivity is almost the same. This study will provide a new approach for the reuse of industrial wastes and carbon dioxide as well as the low-carbon treatment of Zn-contaminated soil, and be of important significance for accelerating the "carbon peak".
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表 1 试验土样的物理化学指标
Table 1 Physical and chemical indexes of soil samples
天然含水率/% 液限/% 塑限/% 最优含水率/% 最大干密度/(g·cm-3) 相对质量密度 pH值 26.1 33.8 22.9 14.2 1.64 2.71 8.78 
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表 2 不同条件影响下的试验方案
Table 2 Test schemes under different conditions
编号 重金属离子浓度/% 固化掺合比 是否碳化 0d-25:75 0.5/1.0/2.0 25∶75 √ 0d-50:50 0.5/1.0/2.0 50∶50 √ 0d-75:25 0.5/1.0/2.0 75∶25 √ 28d-25:75 0.5/1.0/2.0 25∶75 × 28d-50:50 0.5/1.0/2.0 50∶50 × 28d-75:25 0.5/1.0/2.0 75∶25 ×
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