EXPERIMENTAL INVESTIGATION ON CBR PERFORMANCE FOR REINFORCED PEAT – NYLON FIBRE WITH SILICA FUME AS ADDITIVE FOR SUBGRADE SOIL

Peat are can be generalised as organic soil consist of mineral matter, water and more than 65% of the organic content due to the accumulation on the decomposed material. Formation of peat has arising challenging in the development construction due to the high in compressibility, low in shear strength, low bearing capacity and expose to high water content. Thus, this study is conducted to describe the laboratory research on the peat stabilization through chemical stabilization and fiber reinforcement using Ordinary Portland Cement (OPC) as a binding agent and silica fume with nylon fiber as the additives. The basic properties test was conducted on the current peat from Kampung Meranek-Langsat, Kota Samarahan and is classified as Hemic, H5. California Bearing Ratio (CBR) test was performed to evaluate the strength development on the compacted stabilize peat at the optimum moisture content. The silica fume used in this study is aimed to increase the time reaction on hydration when mixed with cement as binding agent. The percentage on the silica fume and cement (10% and 5%) by the weight of dry peat are keep constant throughout this study. The addition of nylon fiber as the fiber reinforcement are varies 0.3%, 0.5% and 0.8%, respectively by the weight of dry peat. The test sample was conducted according to the curing period of 7, 14 and 28 days, respectively. The laboratory test results show that the CBR value obtained from the treated peat was increase to 39.5% through the mix design of cement (5%), silica fume (10%) and nylon fiber (0.8%). However, the addition of 0.5% of nylon fiber show the reduction of CBR value up to 16.67% after cured for 28 days as the targeted strength is 20% of the upper boundary on the subgrade design category. The analysis show that the performance on the CBR value of other design mix are achieving the minimum requirement of 5% CBR value for road subgrade category based on the JKR Standard Specification for Road Work. Thus, the experimental investigation on the CBR performance through the mix design cement (5%), silica fume (10%) and nylon fiber (0.8%) are found to be optimum design mix and also recommended to be used on the subgrade design for road subgrade category of SG 2 in stabilizing the road subgrade for low volume road