NMR–based experimental study on basic physicomechanical properties of saline clay

Abstract

In this paper, the effect of salts (Na₂SO₄,NaCl) on the physicomechanical properties of clay was investigated using the volumetric flask test,Atterberg limits test, and the triaxial shear test, based on the microscopic perspective of pore scale analysis of soil by nuclear magnetic resonance scanning (NMR) technology. The results show that in Na₂SO₄ solution and NaCl solution, the decrease of double layer thickness and the increase of PH value caused by the increase of cation concentration are the main reasons for the gradual decrease of soil Atterberg limits,adsorbed bound water (ABW) content and shear strength. In addition, when the cation concentration is the same, SO2- 4 has a greater barrier effect like semi-permeable film than Cl⁻, which makes the double layer thickness of Na₂SO₄ solution thinner than NaCl solution, the Atterberg limits and ABW content is further reduced; Meanwhile, SO2- 4 has greater intergranular repulsion on the particle surface compared to Cl⁻, forming a larger pore structure further deteriorating the soil structure and reducing the soil shear strength. It provides more support for studying the effect of salt on the physical and mechanical properties of clay.