Physicochemical and compressibility characteristics of dispersive clay under freeze-thaw cycles and soaking in northeastern China

Dispersive clay is a special soil, and the clay particles are easily dissolved in low-salinity water. In northeastern China, frost-heave cracks and subsidence have formed in the dispersive clay subgrades of newly constructed roads. The physicochemical and compressibility characteristics of the dispersive clays that underwent freeze-thaw (F-T) cycles and soaking changed. An experimental study on the physicochemical and compressibility characteristics of dispersive clays under F-T cycles and soaking was conducted to explore the effects of these processes on the state of the clay. The results reveal that after the F-T cycles and soaking, the sodium and potassium ions in the clays decreased by 91-95%. The pH value decreased from 9.24 to 7.47. The particle sizes of the silt and clay, including 0.075-0.005 mm and < 0.005 mm, the liquid limit, and specific gravity increased, and the plastic limit remained unchanged. The F-T cycles and soaking had significant effects on the compressibility characteristics of the dispersive clays. The void ratio and the vertical stress of the clay samples exhibited a linear relationship, and the compressive properties of the dispersive and non-dispersive clays were significantly different. The dispersive clay samples exhibited a completely flocculated structure after soaking for about 10 h. Without F-T cycles, a flocculent layer only formed on the surface of the clay samples. Based on the experimental results, a deformation formula that conforms to the compressibility characteristics of dispersive clays was obtained.