Viscosity-temperature effects of petroleum-contaminated soil under synergistic solidification

Temperature affects the occurrence form of petroleum contaminants in the soil, which is a key factor causing the structural instability and secondary environmental contamination. The reasonable control of the viscosity change under temperatures is a scientific problem for the engineering reuse of the petroleum-contaminated soil. The method of viscosity index improvers combined with inorganic materials for solidifying the petroleum-contaminated soil is proposed in this study. The evolution of the viscosity index, viscosity coefficient and consistency index with the temperature is analyzed from the perspective of the petroleum and petroleum-contaminated soil. The viscosity-temperature effects are evaluated, and the relative regulation method is established. The results show that the viscosities of the petroleum and petroleum-contaminated soil are significantly affected by the temperature. The plastic index change rate of the petroleum-contaminated soil at 20℃ is as high as 31.83%, and the viscosity coefficient at 80℃ is 53.82% lower than that at 10℃. The viscosity index improver is helpful in increasing the viscosity index of the petroleum and improving its occurrence stability. As for the petroleum-contaminated soil solidified by 7% of T614 (ethylene propylene copolymer), 7% of T602HB (polymethyl methacrylate) and inorganic materials, the change rates of the viscosity coefficient and consistency index between adjacent temperatures are within 5%, and the overall change range from 10℃ to 80℃ is within 10%. The regulation rate under the synergistic solidification (85.42%) is higher than the accumulation of the single solidified method. The viscosity index improvers and inorganic materials complement each other in the regulation efficiency. The improver optimizes the petroleum distribution in the soil, which can improve the sufficiency of adsorption and solidified reaction. Meanwhile, the solidification of inorganic materials enhances the density of soil structure and strengthens the action of the viscosity index improvers and petroleum. The synergistic solidification of the viscosity index improvers and inorganic materials realizes the regulation of the petroleum-contaminated soil in a wide temperature range, which helps to improve the stability of the petroleum-contaminated soil in the process of engineering reuse.