Effect of Calcium and Sodium Ions in Soft Clay Using Electrokinetic Stabilisation Technique

Abstract

Electrokinetic Stabilisation (EKS) technique is a combination process of electroosmosis and chemical grouting. This study involves the investigation on the EKS technique performances in stabilising soft clay soils. Stabilising agents will assist the EKS technique by inducing it to the soil under direct current and its movements which is governed by the principle of electrokinetic (EK). The objective of this research is to study the effectiveness of EKS technique in increasing the strength of soft clays. Two reactors were set up by using 1.0 M of calcium chloride (CaCl2), sodium silicate (Na2SiO3) as the electrolyte and stainless steel plates as the electrodes. EKS technique was being performed for 21 days period of time with a constant voltage gradient (50 V/m). This technique was carried out in two phases where the difference between them is a combination of the stabilising agent. The two combinations of stabilising agents in phase 1 and phase 2 were CaCl2 – distilled water (DW) and CaCl2 – Na2SiO3, respectively. The difference was, one was using distilled water while the other was using Na2SiO3. Results of the strength, liquid limit (LL), plastic limit (PL), plasticity index (PI), pH and ion concentration test towards untreated and treated soil were presented. Showing the strength of treated soil for both phases was increasing near the cathode section with 27.83 kPa and 27.67 kPa. LL and PI for treated soil showed the highest value which occurred near the cathode, while PL seems consistant with the values from untreated soil. The Calcium (Ca+) and sodium (Na+) concentrations in soil were increasing compared to the untreated soil, hence it has proven that the application of stabilisers in EK treatment is more effective in increasing the strength and the stability of soils.