Study on viscosity-temperature effect of petroleum-contaminated soil under synergistic solidification

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