Effect of deep chemical mixing columns on properties of surrounding soft clay

Abstract

In the study reported in this paper, potassium hydroxide was used as a chemical additive to improve some engineering properties of low-plasticity clay. The experimental study was carried out in two stages. In the first stage, potassium hydroxide was added to dry clay at different ratios, and samples were prepared for unconfined compressive strength (UCS) testing. A scanning electron microscopic analysis was performed on some specimens to monitor the effect of the additive on the clay. The second stage involved using the additive to form deep-mixed columns in soft clay. Changes in the properties of the surrounding soft clay were measured at certain distances from the edges of the columns by carrying out undrained shear strength, pH, electrical conductivity (EC) and water content experiments. According to the test results, the maximum UCS of about 1173 kPa was obtained at a curing time of 28 d and with 15% additive. It was determined that the undrained shear strength, EC and pH values generally increased in all curing times in the area near the edge of the columns with potassium hydroxide, while the water content decreased.