Effect of forced carbonation on the behaviour of a magnesia-stabilised clay soil

Abstract

This paper presents an investigation into the behaviour of a clay soil stabilised with MgO under forced carbonation and comparison with conventional chemical stabilisation methods. The tests were conducted in two groups. In the first group the soil was mixed with 5, 10, 15 and 20% MgO or cement. Unconfined compressive strength (UCS) tests were performed on compacted samples from these mixtures at curing times of 7, 14 and 28 days. In the second group, samples prepared with different percents of MgO were subjected to CO2 under pressures of 0.5, 1.0 and 1.5 bar for periods of 4, 8, 12 and 24 h. The results showed that adding MgO increases the strength of the soil and, like other binders, the amount of increase in strength depends on the percent of MgO and curing time. It is also resulted that the effect of MgO is less than cement in increasing the strength. It was revealed that forced carbonation can facilitate the stabilisation of MgO-stabilised soil in a few hours compared with usual process that takes several days. XRD and SEM results showed that the gained strength is resulted from the interaction between the soil and the agents.