Laboratory experimental study on red mud geopolymer used as road subgrade materials

Red mud is a strong alkaline waste discharged from the process of alumina extraction, which is harmful to the environment and its utilization rate is always low. One of the effective ways to utilize red mud is used as road subgrade material. In this paper, the industrial wastes including red mud, fly ash, slag, and desulfurized gypsum are used as basic raw materials to prepare subgrade filling materials. A series of laboratory tests, such as compaction test, California Bearing Ratio (CBR) test (soaked and non-soaked conditions) and permeability test, are carried out. The physical and mechanical properties, such as maximum dry density, optimum moisture content, CBR value, expansion, permeability coefficient and soaked strength loss rate, of the mixtures with different proportions, were studied. The results can provide reference for the selection of the best proportion scheme and promote the utilization of red mud in subgrade engineering.