Experimental Study on Swelling-compression-shrinkage Behavior of Expansive Soil Treated with Polyetheramine
To address the engineering need for an efficient,rapid,and large-scale approach for treatment of expansive soils,polyetheramine-230 was successfully utilized as a water-soluble stabilizer for expansive soils in this study.Common compaction and filling techniques with varying moisture levels typically employed in the traditional road construction were emulated.The aim was to assess the impact of substituting water with a polyetheramine solution,following specific mixing ratios,on the treatment of expansive soils and its influence on soil properties.Swelling,consolidation,and shrinkage tests were conducted to compare the treatment effects on expansive soils,and different mass ratios of polyetheramine-treated expansive soils were analyzed.The swift adsorption capacity of polyetheramine effectively mitigates the expansion and shrinkage tendencies of expansive soils,bolstering the structural characteristics of the compacted treated soil.When the specimen is prepared with a dry density of 1.62 g·cm-3,the expansive soil can be effectively treated to exhibit a low expansivity,minimal shrinkage,and moderate compressibility.The treatment efficacy is primarily influenced by the dosage of polyetheramine,guided by adsorption mechanisms.However,there exists a treatment threshold,beyond which the complete suppression of expansive and shrinkage characteristics becomes unachievable.The key treatment mechanism was elucidated through an X-ray diffraction analysis of the clay fraction within the expansive soil and scanning electron microscopy images.The initial interlayer spacing of native clay of 1.49 nm decreases to 1.36 nm.This phenomenon can be elucidated by the intercalation effect of polyetheramine,which hinders the ion hydration within the interlayers of montmorillonite minerals.The polyetheramine monolayer uniformly adsorbs onto the montmorillonite mineral layers,impeding the hydration of interlayer calcium ions beyond two layers of water molecules and thereby contracting the interlayer spacing.Furthermore,the water sensitivity of treated soil particles experiences a substantial decrease.The microstructural analysis further elucidates the inhibitory effects on the hydration and strengthening of the soil structure by the adsorption of polyetheramine in the expansive soil.