Effect of Magnesia on Stabilization of Contaminated Clay Soil

Abstract

In this study, the effect of magnesia (MgO) on the stabilization of a clay soil contaminated with glycerol was investigated through a series of experiments. The tests were performed in two groups. In the first group, the natural soil was mixed with 5, 8, and 12% MgO. A set of tests, including unconfined compressive strength (UCS) tests, were conducted on samples prepared at curing times of 7, 14, and 28 days. In addition, a number of samples prepared with different percentages of MgO were subjected to CO2 under a pressure of 0.5 bar for periods of 4, 8, and 24 hours. In the second group, the soil was contaminated with 4, 8, and 12% glycerol and was then mixed with 5, 8, and 12% MgO. A group of tests, similar to the first group, were conducted on the contaminated samples. The results showed that adding MgO to the natural soil and the contaminated soil increases the strength of the soil, and the amount of increase in strength depends on the percentage of MgO and the curing time. During stabilization, the contaminated soil with 8 and 12% glycerol gained more strength than the natural soil. The results also indicated that forced carbonation can facilitate the stabilization of MgO-stabilized natural and contaminated soils in a few hours compared with conventional methods that take several days. Scanning electron microscopy (SEM) results showed that the gained strength for both groups resulted from the interaction between the soil and MgO.