Filler has an important role in the HRS-WC mixture besides aggregates and asphalt due to its functions to fill the void in the asphalt mixture so that it could produce more friction resistance and high interlocking aggregate. The use of filler in the mixture is limited in number because too much filler will lead to the stiffer and easily cracked mixture. On the contrary, the lower values could lead to the easily deformed and too flexible mixture. Previous researchers have studied the use of the

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... waste of crude palm oil (CPO) ash as a filler. This research aims to study the performance of the HRS-WC mixture using CPO ash as a filler. The asphalt content used was 5.9%; 6.33%; 6.75%; 7.18% and 7.6%, while the proportion of CPO ash waste is 0%, 25%, 50%, 75% and 100%. The mixture gradation is made using a gap-graded and half gapgraded mixture. The results showed that the stability is higher when 25% of CPO ash proportion is used, but it is decreased again when the proportion is larger than 25%. The use of a small asphalt content will increase the value of VIM. The flow value decreases when 32% of CPO ash proportion is used and increases again over the use of 32%. The use of a large amount of CPO ash filler in the mixture will increase VMA. While the VFB will decrease if the larger amount of CPO ash is used. The immersion index of the mixture can still be maintained even when the use of CPO ash is increased. The use of CPO ash as a substitute for filler in the HRS mixture -WC must be balanced with the increasing of asphalt mixture.