TENSILE STRENGTH AND DURABILITY OF OIL PALM EMPTY FRUIT BUNCH FIBER IN SOFT SOIL

Abstract

Natural fibers are already being used to stabilize the soil. However, the exact mechanism by which natural fibers improve the shear strength of soil is still not clear, and it varies according to the morphology of each fiber. Its durability in the soil is also an important issue in the use of natural fibers for soil stabilization. This study focused on the strength and durability of oil palm empty fruit bunch (OPEFB) fiber as a stabilizing material for soft clay. The durability was determined according to the changes in tensile strength and friction of the soil after a certain period. The clay was obtained from Banyu Hirang in South Kalimantan. The OPEFB fiber was obtained without further treatment from a palm oil processing plant. Tensile, soil-fiber friction, and unconfined compression tests were conducted for mixtures of fiber and soil. Preparations were made for each test with the same duration and conditions (1, 7, 14, 28, and 90 days) in closed and open conditions. The results showed that the average tensile strength of the fiber before use was 101 MPa. This value decreased sharply after 14 days in the soil, leaving a strength of 35.71 MPa in the open condition and 23.89% in the closed condition on the 90th day. The soil-fiber friction increased with increasing time, reaching 0.15 MPa in both conditions from the initial value of 0.06 MPa. The compressive strength of the soil-fiber mixture also increased with time. The corresponding scanning electron microscope results strengthened the findings of this study.