Crushed coconut shells as an additive for stabilization treatment of subgrade materials / Alif Akhmizan Mohd Jaya

Road pavement is one of the most important, reliable and widely used infrastructure in transportation system. It consists of base, subbase and subgrade course. Subgrade layer is the most essential in road pavement constructions as it will receive stresses from above pavement layers. However, soil settlement is commonly occurred in Malaysia road due to poorly stabilized subgrade layer. Therefore, it is important that subgrade layer have properly stabilized to withstand stresses applied from above to prevent from soil settlement frequently occurs as cost of repair and maintenance are expensive. The purpose of this study is to identify the improvement of subgrade material strength by integrating Crushed Coconut Shell into the Laterite Soil as a subgrade material. To find the possibility, a series of laboratory tests for Laterite Soil has been performed. This includes Particle Size Distribution, Hydrometer, Standard Proctor and California Bearing Ratio (CBR) Testing carried out at the Laboratory of Geotechnics in Faculty of Civil Engineering UiTM Penang. Crushed Coconut Shell with variations of 2%, 4%, 6% and 8% percentage inclusion are being mixed to Laterite Soil as a subgrade material. The CBR value which indicating soil strength parameter for these variations of soils then being compared and lastly, the outcomes from the laboratory testing then validated through comparison with data from previous researches having the same field of study. The highest CBR value of 27.5% where recorded at 4% of Crushed Coconut Shell being added as compared to initial CBR value of 9.06% for unsoaked soil. While for soaked soil, CBR value of 7% were recorded at initial Laterite Soil condition and improved to CBR value of 24.13% when the Laterite Soil was mixed with 4% of Crushed Coconut Shell.