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A concrete material with waste coal gangue and fly ash used for farmland drainage in high groundwater level areas

Wang, Jinman, Qin, Qian, Hu, Sijia, Wu, Kening
Journal of cleaner production 2016 v.112 pp. 631-638
agricultural land, cement, coal, compression strength, concrete, drainage channels, fly ash, gravel, high water table, mining, mixing, permeability, solid wastes, subsidence, subsurface drainage
Because farmland drainage is difficult in coal mining subsidence areas with high groundwater level and the utilization rate of mine solid wastes (including coal gangue and fly ash) is low, this paper predominately discusses the permeability of the concretes composed of coal gangue and fly ash when applied in farmland drainage ditches. In this study, two experiments were designed. One experiment investigated the permeability and compressive strength of the concrete that used waste coal gangue and fly ash. The experiment consisted of five mixes: using waste coal gangue to replace 25% and 15% of the gravel, using fly ash to replace 10% and 15% of the ordinary Portland cement, and a blank control. The other experiment investigated the permeable rate of an indoor simulation drainage ditch lined with the material that had the mixing proportion of mix V from experiment one; this mixing proportion was found to have the largest permeability coefficient and also satisfied the compressive strength standard. The results of this study indicate that the concrete using waste coal gangue and fly ash had better water permeability than ordinary concrete. The concrete in this study had a high subsurface drainage modulus, making it feasible for application in coal mining subsidence areas with high groundwater levels. Moreover, partial replacement of ordinary Portland cement by fly ash and coarse aggregate by coal gangue can alleviate environmental problems.