Resilient modulus of double layer porous asphalt: application of alkali treated coconut shell and fiber as aggregate replacement

Abstract

Coconut shell and coconut fiber are the new waste that have been concerned in the highway asphalt pavement industry lately. This paper has studied about the effect of coconut shell and coconut fiber to the resilient modulus of double layer porous asphalt (DLPA). The coconut shell has been substitute to the double layer porous asphalt by 5%, 10% and 15 % of the aggregate with 5 mm size by weight while coconut fiber was added to the asphalt incorporating 0.3% and 0.5% by weight. Before mixing with others aggregate, coconut shell and coconut fiber was treated with 5%wt NaOH to reduce it water absorption ability. The samples were prepared by using Marshall Method. The result shows that DLPA with 10% has better resilient modulus under 25ºC temperature for unaged and aged samples. However, the sample with coconut fiber has lower resilient modulus as the amount of coconut fiber has increased. In general, the substitution of 10% coconut shell provided better resilient modulus among the percentages that have been chosen.