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چکیده
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The most significant environmental problem caused by landfills is the contamination of underground water sources with toxic and polluted substances. Natural clay (NC) is used in landfills to reduce permeability; however, in cold regions, the freeze-thaw (F-T) cycles increase permeability. The best solution is to use the waste materials deposited in landfills to stabilize the soil at the bottom of landfills. The waste materials selected in this study were waste glass powder (WGP = 0, 5, 10, 15, and 20%) and calcium carbide residue (CCR = 0, 3, 7, 10, and 13%), which are used as geopolymer for soil stabilization. Unconfined compressive strength, permeability, frost depth, volume change, direct shear, and microstructural tests (FESEM and BET) were conducted to investigate the effect of F-T cycles on permeability accurately. The results showed that the stabilized sample with 15% WGP and 7% CCR (CG15C7) had the lowest permeability and the highest resistance against F-T cycles. In the CG15C7 sample, in the condition without the F-T cycle and after 12 F-T cycles, 97% and 83% immobilization of lead (Pb) had occurred, respectively. For all samples, F-T cycles increased the soil pore volume, thereby increasing permeability; however, the soil pore diameter decreased while the pore number increased. For clay soils subjected to F-T cycles, the results of the present study will be particularly useful from an environmental standpoint
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