ANALYSIS OF LOCAL SANDED SOIL WITH COCONUT COIR FIBER REINFORCEMENT AS SUBGRADE ON STRUCTURAL PAVEMENT

Soil is the important material in a construction work as the basis for foundation, so it takes a soil that must have a high bearing capacity soil with a small decrease. This study was conducted to determine the effect of coconut (coir) fiber to the density of the soil , the California Bearing Ratio (CBR) value and the bearing capacity generated in locally sandy soil. Tests conducted on the soil involved testing the physical properties (sieve analysis test and specific gravity test) and mechanical properties (compaction test , unsoaked and soaked CBR test). The testing of coconut coir fibre are density test and tensile strength test . The length variation of coir fibre used are 1.5-2 cm and 2.5- 3 cm with the addition of coir fiber percentage of 0% , 0.5% , 1% and 1.5% . The result showed that the addition of coir fiber can be increase CBR value and bearing capacity of sanded soil. At unsoaked condition, the highest CBR value was about 51,87% and bearing capacity was 9,14 which are reached at 1,5% percentage of coir fiber and 1,5- 2 cm of coir fiber long. While in soaked condition, the highest CBR value was about 38,88% and bearing capacity was 8,59 which are reached at 0,5-1% percentage of coir fiber and 1,5-2 cm of coir fiber long. It is concluded that proportion of 0.78% coir fiber and 1,5-2 cm of length in a soil is optimum percentage of materials having maximum soaked CBR value. Hence, this proportion may be economically used in road pavement and embankments.