Experimental study on the effect of temperature-alkali interaction on the shear strength of compacted bentonite

Abstract

Abstract The influence of temperature and alkali solutions on shear strength were investigated by conducting undrained direct shear tests on compacted bentonite in a simulated thermal alkali environment. The micro-level changes in bentonite under thermal alkali conditions were analyzed using SEM tests. The study found that an increase in the concentration of alkali solution and temperature led to an improvement in the peak shear strength of bentonite and a delay in the corresponding peak shear displacement. An increase in the concentration of alkali solution also resulted in an improvement in the cohesion and internal friction angle of bentonite. Under the same conditions, the formation of K-linkage and cation exchange resulted in a stronger enhancement of the shear resistance of bentonite in KOH solution compared to NaOH solution. Furthermore, an increase in temperature caused interlayer dehydration under the same conditions, leading to shrinkage of the crystal layer. This strengthened the skeleton and promoted alkali erosion, increasing porosity and promoting the reaction between K + and bentonite, thus enhancing the shear strength of the specimen.