The resilient modulus and ageing index of palm kernel shell asphalt mixture for medium traffic flow at different temperatures

The main problem with roads is pavement failures due to cracking, fatigue, and rutting. This study uses varying percentages of 10, 20 and 30% palm kernel shell (PKS) by weight of the total aggregates as a partial replacement for coarse aggregate in asphalt mixtures mixed with 60/70 penetration grade bitumen to enhance the pavement performance. The preparation of asphalt mixture samples uses the Marshall Mix Design Method, and the asphalt mixtures were compacted at 50 blows to simulate medium traffic flow and subjected to short-term ageing (STA) and long-term ageing (LTA) conditions. The resilient modulus (MR) test was conducted at 25 and 400C to assess the fatigue and rutting of the mix design samples and calculates the ageing index (Al) to evaluate the effect of PKS in delaying the ageing of asphalt mixtures. Results revealed that substituting the coarse aggregate with 10 and 20% PKS increased the asphalt mixtures' resistance to fatigue by 0.6% and 1.1% respectively for STA samples and 2.0% and 2.3% respectively for LTA samples. Results at high temperature and for all ageing conditions showed that only 10% PKS asphalt mixture was more resistant against rutting failure with higher MR value of 0.7% and 0.6% subjected to STA and LTA when compared to control sample. Replacing the coarse aggregate with 10% PKS lowered the Al value of the asphalt mixture which slower the oxidation process.