Reactive magnesia (MgO)-activated ground granulated blast furnace slag (GGBS) is a newly developed binder for soil stabilization/solidification. It can be used as an alternative of conventional hydraulic binders for the stabilization/solidification of heavy metal-contaminated soils. Acid rain exposure has been found to weaken the heavy metal immobilization in solidified/stabilized soils in the long term. However, very limited studies have been conducted to investigate the effect of acid rain on the physical and strength properties of GGBS–MgO-stabilized heavy metal-contaminated soils. In this study, GGBS–MgO-stabilized lead (Pb)-contaminated soils are subjected to the semi-dynamic leaching test using the simulated acid rain (SAR) as leachant, which has pH values of 2.0, 3.0, 4.0, and 5.0. Deionized water (pH 7.0) is also used for comparison. Dry density, soil pH, needle penetration depth, and unconfined compressive strength (q_u) of the solidified/stabilized soils are measured after the leaching test. The results show that exposure to SAR yields reduction in q_u and soil pH, whereas the needle penetration depth increases and dry density changes only marginally. The q_u of the solidified/stabilized soils increases noticeably with increased GGBS–MgO content. It is also found that the stabilized Pb-contaminated soil exhibits lower q_u than its clean soil counterpart. Furthermore, a quantitative relationship is proposed to correlate the normalized needle penetration resistance with the normalized q_u. Finally, a multiple linear regression is performed to statistically reveal the dependence of soil strength on three independent variables, which are SAR pH, Pb concentration and binder content.

中文翻译：

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酸雨对GGBS–MgO固化/稳定的Pb污染黏土的物理，力学和化学性质的影响

活性氧化镁（MgO）活化的高炉矿渣（GGBS）是一种新开发的用于土壤稳定/固化的粘结剂。它可以用作常规水硬性粘结剂的替代品，以稳定/固化重金属污染的土壤。从长期来看，发现酸雨暴露会削弱重金属在固化/稳定化土壤中的固定。然而，进行了非常有限的研究来研究酸雨对GGBS–MgO稳定的重金属污染土壤的物理和强度特性的影响。在这项研究中，使用模拟酸雨（SAR）作为渗滤液，对GGBS–MgO稳定的铅（Pb）污染的土壤进行半动态浸出试验，其pH值为2.0、3.0、4.0和5.0。去离子水（pH 7.0）也用于比较。q _ù）的固化/稳定化的土壤的是在浸出试验后测得的。结果表明，暴露于SAR会降低q _u和土壤pH值，而针刺深度增加且干密度仅略有变化。的q _ü的固化/稳定化的土壤的增加显着增加矿粉-MgO含量。还发现，稳定的被Pb污染的土壤比其清洁的土壤具有更低的q _u。此外，提出了定量关系以将归一化的针头穿透阻力与归一化的q _{u相关联。}。最后，进行多元线性回归以统计地揭示土壤强度对三个独立变量的依赖性，这三个独立变量是SAR pH，Pb浓度和粘合剂含量。