Expansive Soil Treatment with Powder-Form Polymer Soil Stabilizer

The swell-shrink characteristic of expansive soil imposes a serious challenge that threatens the safety and durability of expansive soil slopes. This paper proposes a novel application of the powder-form polymer soil stabilizer (PA) to stabilize the expansive soil. The PA can interact with the active groups in expansive soil to form a flexible three-dimensional gel structure, so soil particles can be cemented by the PA to inhibit soil deformation. To assess the inhibitory effect of PA on the swelling and shrinkage behavior of expansive soil, a series of experiments including the limit moisture content test, the free swell ratio test, the one-dimensional swell test, and the linear shrinkage test were performed on treated soils with PA content of 0–8%. Meanwhile, the corresponding mechanism was investigated by microstructure observations. Results showed that the PA had a significant influence on the properties of expansive soil. With the increase of PA content, the index for swelling-shrinkage properties such as plasticity index, free swell ratio, one-dimensional swell ratio, and linear shrinkage ratio all showed a decreasing trend. This was explained by the excellent cohesive interfaces between PA and soil particles observed from the ESEM.