Effect of Different Kenaf Core Contents and Sizes as Filler on the Properties of Road

Kenaf core is less utilised due to its shorter fibre compared to kenaf bast and it is a waste to discard kenaf core fibre since it consists 60% dry weight of the stem. This study was conducted to investigate on the utilisation of kenaf core as alternative filler in hot melt asphalt (HMA) mixtures. HMA mixtures containing kenaf core at various percentages; 0.3%, 0.5%, and 0.7% and sizes; 75 μm and 150 μm were produced. Indirect Tensile Modulus Test was used to evaluate the properties of the sample blocks produced. Results show that 0.3% is the optimum percentage of kenaf core powder and fibre as filler content in HMA according to its value of resilient modulus compared to 0.5% and 0.7%. The more content of kenaf core were added into the mixtures would create higher air voids. This is because additional content or size of kenaf core in mixture was able to reduce adhesion between the aggregates with bitumen. Moreover, the more content of kenaf core added into mixture resulted in reduction of the value of resilient modulus at 25°C when the increasing traffic loads from 1000 N to 3000 N were applied to the produced sample blocks. The value of resilient modulus obtained which is lower than the Public Works Department (JKR) specification caused the road to be less rigid in sustaining stress and deformed road in a short period of time.