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Palm Kernel Shell as Partial Coarse Aggregate Replacement in Asphalt Mixture: Optimum Binder Content and Volumetric Properties Investigation

Pavement failures such as fatigue, rutting, cracking, bleeding, and stripping are typical pavement deterioration. Researchers have been experimenting with pavement modification to overcome these problems. This study determines the optimum binder content (OBC) for modifying an asphalt mixture with a partial replacement of coarse aggregate (5mm-14mm sieve size) with palm kernel shell (PKS). A 60/70 penetration grade bitumen was mixed with 10, 20 and 30% PKS at selected aggregate gradation following the Public Work Department of Malaysia (JKR/SPJ/2008-S4) specification. The preparation of 60 samples of unmodified and modified asphalt mixture employed the Marshall Method compacted with 75 blows. The OBC was determined based on five volumetric properties of asphalt mixture namely stability, flow, bulk density, void filled with asphalt, and void in total mix. The OBC and volumetric properties of the modified PKS asphalt mixture samples were compared with unmodified asphalt mixture samples in accordance to the specification. Results showed that the OBC sample with 30% aggregate replacement produced the highest OBC value of 5.53% relative to the control sample with 5.40% OBC. The trend for OBC with PKS replacement begins with 10% PKS with 5.30% OBC, 20% PKS with 5.32% OBC and 30% PKS. All volumetric properties of the PKS samples are within the specification limit. Thus, PKS has a promising potential as a coarse aggregate replacement in asphalt mixture.