Some mechanical and chemical properties of cement stabilized Malaysian soft clay

Soft clays are defined as cohesive soil whose water content is higher than its liquid limits. Materials such as these display extremely low yield stresses, high compressibility, low strength, low permeability and consequently low quality for construction. Thus, soil-cement mixing is adopted to improve the ground conditions by enhancing the strength and deformation characteristics of the soft clays. For the above mentioned reasons, a series oflaboratory tests were carried out to study some fundamental mechanical and chemical properties of cement stabilized soft clay. The test specimens were prepared by varying the portion of ordinary Portland cement to the soft clay sample retrieved from the test site of RECESS (Research Centre for Soft Soil) at UTHM. Comparisons were made for both mechanical and chemical properties by relating the effects of cement stabilized clay of homogeneous and columnar system specimens for 0,5 and 10 % cement and curing for 3, 28 and 56 days. The mechanical properties examined included one-dimensional compressibility and undrained shear strength, while the chemical properties included pH values and the percentage of oxide concentration. For the mechanical properties, both homogeneous and columnar system specimens were prepared to examine the effect of different cement contents and curing periods on the stabilized soil. The one�dimensional compressibility test was conducted using an oedometer, while a direct shear box was used for measuring the undrained shear strength. Chemical properties of the stabilized material were examined using the X-Ray Fluorescence (XRF) method to obtain the percentage of oxide concentration while a pH meter was used to determine the pH values. The chemical study was also to ascertain the extent of leaching effect from the stabilized column to the surrounding soils. The higher the value of cement content, the greater is the enhancement of the yield stress and the decrease of compression index. The value of cement content in a specimen is a more vi active parameter than the curing period. It can be proposed the following relationship for RECESS soft clay from this study: cry' = 1.5871 <. The chemical results showed that cement-stabilized column give environmental effects to the soil surrounding the column. The pH values for cement content of 5 % and 10 % in the soil-cement column specimens gradually decreases with the curing days for both consolidated and without consolidated specimens. Soil-cement column specimen with consolidation gave a higher pH compare to the specimens without consolidation. Major to minor relative values ofthe percentage of oxide concentrations are Si02 > Ah03> Fe203 > S03 > K20 > CaO

One Dimensional Compressibility Characteristics of Clay Stabilised with Cement-Rubber Chips

Pre-construction treatment of soft and weak deposits is necessary to ensure safety and stability of the building or infrastructure. A common treatment of such soft soils is the stabilization method, with cement and/ or lime addition to the soil to form stabilized column or platforms through mixing. This paper focuses on the 1-D compressibility characteristics of kaolin as base clay, admixed with cement as the binder and rubberchips as an additive. This approach in engineering application is also aimed at reducing the huge stockpile of the waste tyres and its potential impact on the environment. In the study, cylindrical stabilized clay specimens were prepared with various rubberchips contents and cement, and then aged for 28 days before being tested in an automated one-dimensional compressibility apparatus (i.e. Geocomp LoadTrac-II). Analysis was carried out by relating the effects of 0, 2 or 4 % cement as well as 0, 5, 10 and 15 % rubberchips addition to the base clay. The compressibility was found to decrease significantly with small quantities of cement-rubberchips addition, though the main contributor of strength came from the cement. Also, comparison of the gradient of the reloading curves for stress levels less than the preconsolidation stress and also beyond that stress is presented. The prediction of the yield stress or settlement with higher or lower cement or rubberchips content was also analyzed. Overall, the cement-rubberchips proved to effectively increase the1-D stiffness and therefore reduce the settlements.Keywords

Leachability and strength of kaolin stabilized with cement and rubber

Yearly, the disposal of used tyres is a major environmental problem for countries all over the world. This causes environmental hazards such as uncontrolled fire, consume landfill space, breeding ground for mosquitoes and contaminating the soil and vegetation. Hence, urgent steps were identified to produce new methods of recycling the waste tyres to solve this hazard. This study reviews the feasibility of using waste tyres in the form of rubber chips with cement to stabilize soft clay and the effect to the environment. The focus of this study was mainly the strength and leachability characteristics of kaolin as base clay, admixed with cement as the binder and rubber chips as an additive. Leaching test is used to evaluate the performance of cementitious materials for stabilization and solidification (S &amp; S) of hazardous materials such as waste or contaminated soil. In this study, cylindrical stabilized clay specimens were prepared with various rubber chips contents and cement, and then aged for 28 days. Cylindrical specimens were then subjected to unconfined compressive strength test (using Geocomp LoadTrac II) and the specimens were later dried in oven at 105&deg; before tested for leaching tests. These leaching methods are Acid Neutralization Capacity Test (ANC) and Synthetic Precipitation Leaching Procedure (SPLP). The solidified samples were checked on six different heavy metals, namely copper, chromium, cadmium, arsenic, zinc and plumbum. Analysis was carried out by relating the effects of 0, 2 or 4 % cement as well as 0, 5, 10 and 15 % rubber chips addition to the base clay and its leachability. As observed, the curing of specimen for 28 days was in a range of 66.24 to 249.4 kPa. Specimen with 4 % cement is able to produce ANC9 of about 0.13 meq HNO3/g specimen. However specimen with 0 % and 2 % cement for different rubberchips content shows that the specimen do not have the capacity to neutralize acid at pH 9. Therefore, more cement (&gt; 4 %) is needed to achieve ANC9. SPLP results showed that all six different heavy metals tested do not exceed the approved limit for drinking water by World Health Organization (WHO), United States Environmental Protection Agency (USEPA) and Ministry of Health in Malaysia

The Potential of Using Rubberchips as a Soft Clay Stabilizer Enhancing Agent

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