Journal of Civil and Environmental Engineering

Enhancing Asphalt Concrete Performance with Scoria as Fine Aggregate and Recycled Waste Hollow Concrete Block as Fillers

Abstract

Ashenafi Tsega*, Tibebu Birega and Robeam Solomon

Asphalt concrete mix, comprising 4-6% asphalt bitumen and 90-96% aggregate, requires significant quantities of crushed aggregate, leading to material shortages and high costs. This study aims to enhance asphalt concrete performance by using scoria as fine aggregate and recycled Waste Hollow Concrete Block (WHCB) as fillers. Incremental scoria levels ranging from 10% to 40% were tested in the marshal mix, with 20% replacement meeting Ethiopian road authority specifications. Tests with 25%, 50%, and 75% waste hollow concrete block showed compliance up to 50%, with performance declining at 75%. The modified mix required slightly more bitumen than the control mix. Tensile Strength Ratio (TSR) and indirect tensile strength tests revealed that the unmodified hot mix asphalt outperformed the modified mix by 14.27% in wet and 7.87% in dry conditions. The TSR of the unmodified mix was 81.96%, while the modified mix achieved 76.34%, exceeding the 75% minimum requirement set by the Ethiopian Road Authority. The study concludes that using 25% waste hollow concrete block filler and 20% scoria fine aggregate in asphalt concrete production yields positive outcomes and meets specification requirements.