Utilization of Rice Husk Ash and Coconut Fibers to Enhance Pervious Concrete in Sustainable Pavement Systems

Abstract

This study examined the influence of rice husk ash and coconut fiber on the mechanical and durability performance of pervious concrete. The concrete mixes were prepared without fine aggregates to maintain high porosity, using a water-to-cement ratio of 0.30 and a coarse aggregate-to-cement ratio of 4.5:1. Rice husk ash replaced 10% or 12% of the cement by weight, while coconut fiber was added at 0.3% and 0.5% by volume. The results showed that both additives slightly reduced porosity and permeability, yet the compressive strength remained above the minimum threshold of 7 MPa. The mix containing 0.3% coconut fiber achieved the highest strength of 11.0 MPa. The most optimal mix combined 10% rice husk ash with 0.5% coconut fiber, producing a porosity of 21%, permeability of 3.8 mm/s, compressive strength of 10 MPa, and water absorption of 250 L/m³. Durability also improved in fiber-containing mixes, as observed from reduced damage under wet-dry cycles. The addition of these natural materials contributed to enhanced mechanical performance and resistance to water-related degradation, making the mix suitable for sustainable pavement systems. Overall, the findings confirmed that rice husk ash and coconut fiber can be effectively utilized as partial replacements in pervious concrete without compromising structural integrity.