Experimental Study on Mechanical Strength of Diesel-Contaminated Red Clay Solidified with Lime and Fly Ash

Diesel-polluted soil is unstable and easy to migrate with environmental changes and causes secondary pollution. In this paper, 0# diesel is used as the pollutant, and lime fly ash is selected as the solidifying material. This paper selects four curing ages of 7D, 14D, 21D, and 28D and four pollution concentrations of 0%, 5%, 10%, and 15%. 20%, 25%, 30%, and 35% four moisture content variables were used to conduct an unconfined compression test, direct shear test, and scanning electron microscope test on diesel-contaminated red clay. The results show that the curing age significantly affects the curing effect, and the curing age of 21D is the optimal age. The mechanical properties of the cured soil were the best at the optimum age and when the pollution concentration was 5%. The mechanical properties of the solidified soil with a moisture content of 30% are the best at the optimal age and the same pollution concentration. Additionally, the scanning electron microscope data indicate that when the pollution concentration increases, the cement created by the interaction of lime, fly ash, and pozzolan increasingly forms. The “oil film” generated by diesel oil seeping into the soil is bound and unable to fill the soil’s pores, hence reducing the soil’s strength.