No abstract

Abtract. 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 (CaCl 2 ), sodium silicate (Na 2 SiO 3 ) 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 CaCl 2 -distilled water (DW) and CaCl 2 -Na 2 SiO 3 , respectively. The difference was, one was using distilled water while the other was using Na 2 SiO 3. 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.

ABSTRACT:The disposal of dredged marine soils (DMS) into the ocean or on land are unsatisfactory in managing its large quantity which indicates a high demand on new ocean and land disposal. DMS are classified as contaminated waste that contain of organic matter and heavy metals. Contaminated DMS can harm aquatic organism, animals and human. It must be disposed safely to ensure the contaminants are not released. By reusing the DMS as geomaterial or fill for reclamation works, it will minimize the impact to environment. The treatment techniques towards DMS are an essential and necessary in enhancing its engineering properties and assuring the effectiveness for a long-term solution. This paper presents a preliminary study in solidifying the Kuala Perlis DMS (3.4 LL) with lowest dosage of cement (1 -10 %) at different curing period (3, 7, 14 and 28 days). It shows the undrained shear strength (cu) value of cement-solidified were increased compare to the raw DMS. The results for cement dosage above 7 % shows a good improvement in cu value and the strength development were found increased after 3 days of curing. It was explained that the lowest water-cement (w/c) ratio tend to have a higher cu value of the cement-solidified DMS.

Abstract. Recently, Stabilization/Solidification (S/S) method has been focusing on the usage of agricultural waste as an alternative towards environmental friendly and low cost material to substitute cement. The aim of this study is to determine the leachability of lead contaminated soil by using sugarcane bagasse as partial replacement of cement in S/S method. In this study, different percentages (2.5%, 5% and 7.5%) of treated and untreated sugarcane bagasse have been utilized as a partial replacement to cement. Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) have been conducted to determine the leachability of lead contaminated soil. The results indicate that with 7.5% of treated sugarcane bagasse replacement in cement resulted significant reduction of lead contaminant in soil up to 99 % after 28 days. As a conclusion, treated sugarcane bagasse could be an alternative low cost material in the S/S method as it can significantly reduce the remediation cost normally incurred by the usage of cement.

This paper outlines the monitoring and soil fabric results from an experimental study of electrokinetic stabilisation (EKS) technique. The monitoring results were important in assessing the efficiency of the technique towards Batu Pahat marine clay. Two reactors were set up; 1.0 M of calcium chloride (CaCl2) and sodium silicate (Na2SiO3) as the electrolyte and stainless steel plates as the electrodes. EKS technique was continued for 21 days with a constant voltage gradient (50 V/m). This technique was performed in two phases where the alteration of EKS was the combination of stabilizers used. The combinations of stabilizers in phase 1 and 2 were CaCl2 -distilled water (DW) and CaCl2 -Na2SiO3, respectively. The technique was monitored using electric current, total inflow and outflow of electrolytes and pH of electrolytes. It showed fluctuated profiles of electric current for both phases, attributed by the introduction of calcium ions from the anode compartment. The inflow and outflow of electrolytes results showed that electromigration and electroosmosis occurred during EKS and it indicated the movement of anion and cation to the opposite direction. The pH of electrolytes kept constant value and balanced by electrolysis process at the cathode. Image of soil fabric for untreated and treated clay were presented where most images shows a flaky particles. The observation of those images indirectly explained the effect of cementation behavior of treated clay.