Usage of two biomass ashes as filler in hot mix asphalt

Today, waste materials have been increasingly utilized as alternative raw materials in asphalt mixtures in order to decrease construction costs, conserve natural resources and reduce environmental problems. The main purpose of this research is to investigate the potential of using two biomass ashes, which are agricultural waste/byproducts namely rice husk ash (RHA) and date seed ash (DSA), as filler material in hot mix asphalt (HMA) by replacing conventional filler at different percentages. The percentages of DSA and RHA separately used in the mixtures were: 0%, 25%, 50%, 75% and 100%. The effects of DSA and RHA fillers on mechanical properties of asphalt mixtures were assessed using Marshall stability, MQ, indirect tensile stiffness modulus, wheel track and four point bending fatigue tests. Furthermore, the asphalt mastics were produced to evaluate the effect of fillers on mastic viscosity. Based on the results, asphalt mixtures with DSA and RHA fillers showed higher stability and stiffness modulus in comparison with the control mixture. Also, using biomass ashes improved the thermal sensitivity of mixtures and the adhesive force between asphalt and aggregates, which caused an enhancement in rutting resistance and fatigue life of HMA mixtures.