Water entrance-and-release capacity and contact angle of improved granite residual soil

Abstract

Water entrance-and-release capacity of granite residual soil is closely related to the special mechanical properties of softening and disintegration. Existing research on the improved soil focuses on the macro-mechanical properites and variation of micro-structure of soil, and ignores the influence of curing agent on the soil surface properties. To explore the water entrance-and-release capacity of granite residual soil improved by curing agent and the variation of three-phase antenna, the water drop infiltration test, contact angle measurement test, water inlet test and water entrance-and-release test were carried out. Combined with scanning electron microscopy and infrared spectroscopy, the influence mechanism of microstructure and chemical composition of granite residual soil under different curing agents on entrance-and-release of granite residual soil was analyzed qualitatively and quantitatively. The results show that (1) different contents of curing agent can affect the surface water repellency of granite residual soil to different degrees. With the increasing curing agent content, the surface water repellency of soil increases, the three-phase antenna becomes larger, and the water release capacity weakens. (2) The improvement effect of lime is stronger than that of cement and kaolin, and the change of water entrance-and-release capacity of modified soil is obviously correlated to the change of water repulsion and three-phase antenna. The change of water entrance-and-release capacity of improved granite residual soil is caused by the changes of soil internal structure and surface property. (3) Cement and lime mainly rely on ion exchange agglomeration, soil curing agent's wrapping effect on soil particles, hard coagulation reaction and carbonation to weaken the double electric layer and surface free energy on the surface of soil particles, so that the soil water repulsion and initial contact angle become larger. Kaolin mainly depends on its adsorption of water molecules, but it has little effect on the water repellency and contact angle of soil. The results can provide a scientific basis for the variation of contact angle caused by the change of soil surface properties by curing agent, and also provide a reference for the selection of improvement in practical engineering with different permeability requirements.

Keywords

• granite residual soil
• water entrance-and-release capacity
• microstructure
• contact angle
• curing mechanism