Identification of the influence of electrokinetic soil improvement on the microstructure, physical and mechanical properties of expansive soil

Abstract

Clay is a soil with low permeability. Clay is considered a problematic soil besides peat soil. The main problem with clay is its mineralogy. Expansive clay soils contain the minerals kaolinite, illite, and montmorillonite. Montmorillonite has weak bonds between its layers. These weak bonds make the soil easily incorporated, one of which is water. Water approaching expansive soil will bond with it and cause swelling. Expansive soil improvement studies have been conducted. One of them is electrokinetic. Expansive soil from Karawang, Indonesia is one of the soils with a high swelling index. This is because montmorillonite is inside. The Karawang expansive soil will be improved by flowing several salt solutions with various voltages. The applied voltage will flow the solution from the cathode to the anode and fill the clay minerals. Four voltage variants will be applied with the same electrokinetic application time. The mineralogy of soil before and after electrokinetic improvement undergone changes. The changes can be seen from SEM and XRF testing. The improved soil changed its physical properties from clay with high plasticity to clay with low plasticity. Chemical elements from salt solution trap in montmorillonite then make positive changes in soil mineralogy, soil physical properties, and mechanical properties. The mechanical properties can be seen in a decrease in the C value and an increase in the soil angle of friction after electrokinetic improvement. After electrokinetic improvement using calcium chloride, the lowest soil cohesion value was 12.356 kg/cm2 at 12 V. After electrokinetic improvement with calcium dioxide, the lowest cohesion value at 12 V voltage is 19.22 kg/cm2. In barium sulfate solution, the lowest soil cohesion at 15 V is 12.16 kg/cm2. The soil swelling value decreased after improvement with calcium chloride to 0.008 % from 0.027 %. The research results in calcium chloride with 12 V give optimized results on soil improvement with electrokinetics