Experimental Study of Improvement of Loess-Like Sodium Sulfate Saline Soil Using the Consolid System

Abstract

Given the ineffectiveness of traditional curing agents such as lime and cement in treating salt expansion of loess-like sulfate saline soils, this study examined the impact of the environmentally friendly Consolid system on compaction, salt-frost heave, and dissolution of sulfate saline soils. The results indicate that as the salt content increased, the optimum water content of saline soil also increased, whereas the maximum dry density decreased. Additionally, the compaction properties of saline soil were greatly influenced by the Consolid system; at the same salt content, an increase in the Consolid system dosage led to an increase in the optimum water content of the solidified soil and a decrease in the maximum dry density. Salt-frost heave increased with the increase in salt content and the number of freeze-thaw cycles. When the salt content was 1% or more, there was obvious accumulative and residual salt-frost heave with freeze-thaw cycles, and both the accumulative and residual salt-frost heave were linearly and positively correlated with the number of freeze–thaw cycles. When the Consolid system dosage was 1%, 3%, and 10%, it significantly improved the salt-frost heave of saline soils with salt content of 0.5%, 1%, and 2%, respectively. However, when the salt content was 3%, even when the Consolid system dosage reaches 15%, there is a risk of salt expansion after several freeze–thaw cycles. Furthermore, the Consolid system failed to improve the salt-frost heave of saline soils with 5% salt content. The dissolution coefficient of saline soils gradually increased with the increase in salt content. The Consolid system has a significant effect on improving the dissolution of saline soils. The dissolution amount and coefficient of the solidified soil under a 200-kPa immersion load decreased significantly with an increase in Consolid system dosage. Saline soils with 3% and 5% salt content can be improved from medium dissolution to nondissolution at Consolid system dosages of 3% and 5%, respectively. Furthermore, it is important to record and monitor the accumulative salt-frost heave over an extended period to ensure the safety of the project.