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| Mine soil restoration is very important for ecological environment and residents life. This paper presents a study on mine soils, from the Baoshan, Hunan province, China, contaminated with heavy metals and stabilized by using a new phosphate-based binder (KMP) and ordinary portland cement (OPC). Aiming to explore the effects of binder type, binder content (%) and curing age of contaminated soils on environmental safety and strength properties of the soils contaminated with heavy metals in the mining area, toxicity characteristic leaching procedure (TCLP), acid-neutralizing capacity (ANC) test, sequential extraction procedure (BCR), unconfined compression test (UCT), X-ray diffraction (XRD) and scanning electron microscopic (SEM) procedures were carried out. Test results showed that as the curing age was increased from 0 d to 28 d, KMP and OPC stabilized contaminated soil underwent several changes: leaching of Zn and Pb gradually reduced, ANC (β) increased, exchangeable Zn and Pb decreased, residual contents increased and strength improved. When the binder content increases from 4% to 8% at the curing age of 28 d, the concentrations of leached Zn and Pb of KMP stabilized contaminated soil decreased by 64.2% and 60.05%, respectively; its ANC (β) increased by 2.97%; its residual Zn and Pb increased by 1.41 and 3.04 times, respectively; and its strength increased by 12.28%. Meanwhile, the concentrations of leached Zn and Pb of OPC stabilized contaminated soil decreased by 67.01% and 84.03%; its ANC (β) increased by 12.97%; its residual Zn and Pb increased by 1.84 and 1.25 times respectively and its strength increased by 24.05%. At the same curing conditions and binder content, KMP stabilized contaminated soil showed a lower leached Zn and Pb content than that by OPC, a higher ANC (β) by 1.65, more residual Zn and Pb by 41.5% and 89.01% respectively and an enhanced strength by 3.48-10.21%. (10 Points, Times New Roman) |
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| Keywords:phosphate-based binder; stabilization/solidification; heavy metal contaminated soils; mining area; environmental safety |
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