Study on Strength Characteristics of Red Clay Modified by Polyvinyl Alcohol Hydrogel

Abstract:

Taking red clay as the research object and polyvinyl alcohol as the improved material, the effects of different polyrinyl alcohol (PVA) concentrations and curing ages on the strength of red clay were studied by direct shear and non-lateral compressive strength tests, and the microstructure of the improved soil was observed by scanning electron microscopy. The results show that under the same conditions of each curing age, the cohesion and unconfined compressive strength of red clay increase first and then decrease with the increase of PVA concentration. The internal friction angle does not show obvious variation with the increase of PVA concentration, but it is greater than the internal friction angle of red clay. The effect of improving the shear strength and unconfined compressive strength of red clay with 3% PVA is ideal. Microscopic tests show that PVA reacts with soil particles to form a three-dimensional mesh structure with high elasticity and high strength, which is lapped between pores. The network structure formed by low concentration of PVA is incomplete and the cohesive force is weak. With the increase of concentration, the network structure is gradually complete, which can effectively limit the movement of soil particles, so as to improve the shear and compressive strength of soil. However, the higher concentration of PVA leads to the increase of the viscosity of the hydrogel, which affects its uniform mixing with red clay, which is not conducive to the contact between PVA and soil particles, wea-kens the connection between the network structure and soil particles, and reduces the cohesion and unconfined compressive strength.