Laboratory research on evaluating the rutting resistance of natural asphalt concrete mixture

Abstract

The road network in Iraq, particularly in the central and southern regions, suffers from frequent rutting due to harsh conditions, high temperatures, and the limited resistance of Regular Asphalt (RA) mixtures to repeated loading. These deformations reduce the service life of the pavement and increase maintenance costs. This study investigates the potential of improving asphalt mixture performance by incorporating Natural Asphalt (NA) sourced from the Abu Al-Jeer springs in Anbar Governorate. RA is the petroleum asphalt, which was obtained from the Dora oil refinery. The NA underwent two forms of treatment: thermal processing and blending with RA at varying ratios (20 %, 40 %, 60 %, and 80 %). Repeated load tests were performed on six different mixtures at 40 °C, with an applied pressure of 0.138MPa for 6 000 loading cycles. The results showed that mixtures containing treated NA exhibited significantly greater resistance to permanent deformation and in the Resilient Modulus (Mr). Notably, the mix containing 80% of NA showed a 72% reduction in permanent microstrain compared to the mixes containing RA, indicating a significantly improved mechanical performance. These findings suggest that NA is a viable and eco-friendly alternative for improving asphalt mixture performance in hot climates such as Iraq.