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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.

Reusing the dredged marine sediment (DMS) that was spawned from maintenance dredging work will reduce its disposal effect towards the environment. Furthermore, reusing the DMS could optimize the storage capacity of existing confine disposal facilities (CDF) and can prolonging its lifespan. Treating the DMS with an adequate pre-treatment is the best way to manage this sediment in sustainable solution. The purpose of this research is to study the influence of moisture content (w), pH and liquid limit (LL) towards the DMS’s stability after treated with electrokinetic (EK) method. Stainless steel plate was used as the electrode, while distilled water (DW) and calcium chloride (CaCli) were applied as the enhancement agents. The aforementioned enhancement agents are electrically injected into the DMS which causing flow of the solutions through the pores in DMS under 50 V/m of applied direct current. The EK-treated DMS shows increment in strength and it was influenced by w, pH and LL. The dry zone area was created near the anode and wet zone was created near the cathode. The application of CaCh create a better result in physical properties of DMS compared to pure systems. The EK-treated DMS hence could be reuse as a geomaterial in construction activities. Largely, EK has significantly improve the quality of DMS even though the strength increase observed was not homogeneous throughout the specimen.

Nearshore’s facilities are often require frequent and regular maintenance dredging in maintaining appropriate water depths and enlarging the access channel and turning basin. A large amount of sediment was spawned from the dredging work. The dredged marine sediments (DMS) are not apt to be used in construction activities because of its poor geophysical properties. The purpose of this research is to study the improvement in moisture content and strength of DMS by using electrokinetic (EK) method. DMS are classified as a high plasticity silt (MH) with 240.74 % of its natural water content. Stainless steel plate was invoked as the electrode, while distilled water (DW), citric acid (CA) and calcium chloride (CaCl2) were applied as the stabilizing agents. The aforementioned stabilizers are electrically injected into the DMS which causing flow of the solutions through the pores in DMS under 50 V/m of applied direct current (DC). The results of treated DMS are presented in moisture content, undrained shear strength and SEM-EDX analysis. The EK treated DMS shows it increases in strength in the dry zone area after the 14 days treatment. The dry zone area was created near the anode and wet zone was made near the cathode. The application of calcium ions in the treatment had increased the strength and alters the pattern of the soil fabric. Largely, EK has significantly improved the quality of DMS even though the strength increase observed was not homogeneous throughout the specimen.

Contaminated soil is often a problem and typical concern in the developing countries due to the lack of clean soil for development, such as in Malaysia. The objective of this study is to investigate the performance of the available techniques for soil remediation contaminated with lead (Pb) through Stabilisation/Solidification (S/S) technique. In this study, cockle shell powders at different percentages (2.5%, 5% and 7.5%) were added as a partial replacement of cement. Toxicity Characteristics Leaching Procedure (TCLP) was conducted to determine the effectiveness of the S/S technique to treat the contaminated soil. The results showed a 99% reduction of Pb concentration after the contaminated clay soil was treated with S/S technique. The combination of cement and cockle shell powders is very effectively used in the remediation of lead contaminated soil and reducing the amount of cement usage for sustainability approaches.