Evaluating the engineering properties of asphalt mixtures containing RAP aggregates incorporating different wastes as fillers and their effects on the ageing susceptibility

Abstract

Ageing of asphalt mixtures occurs by intrinsic variables (properties and quantity of the binder and air voids) and extrinsic variables (environmental factors) during production and service life. This topic has been studied extensively in the existing literature, but the potential of alternate filler on the ageing resistance of asphalt mixes and the influence of the interaction between filler and asphalt binder has not been thoroughly examined. The underlying objective of this study was to evaluate the ageing resistance potential of four waste fillers, Jarosite (JS), Hydrated Lime mud (HL), Fly Ash (FA) and Sugarcane Ash (SA), compared to conventional fillers, Stone Dust (SD) on the recycled mix. The recycled mixes were prepared with 50% Reclaimed Asphalt Pavement (RAP) material, locally available natural aggregate, VG-10 grade asphalt binder and studied fillers. The performance properties, including cracking resistance, moisture susceptibility, resilient modulus, rutting, and fatigue resistance of unaged and long-term aged recycled asphalt mix, were evaluated in this study. The results indicated that the ageing resistance of recycled mixtures was highly affected by filler type. HL possesses the highest ageing resistance potential, followed by JS, FA, SA, and SD. The results demonstrated that JS and HL filler significantly improved moisture, rutting, and crack resistance in unaged and long-term aged recycled mix, which are critical factors in extending the durability of pavement. JS and HL filler showed lower fatigue life of recycled mix while tested at higher strain levels due to their higher stiffness. In contrast, FA and SA fillers resulted in a mixed value of properties of the recycled mix compared to SD filler. SA filler showed the lowest cracking resistance (Indirect tensile strength value 1420 kPa for unaged mix and 1573 kPa for aged mix) and moisture resistance (Tensile strength ratio value 78% for unaged mix and 75% for aged mix) among all fillers. The recycled asphalt mix containing SA was found to be highly susceptible to moisture damage, cracking and ageing. The overall conclusions of this study ascertain that the ageing resistance potential of HL was highest among the studied waste fillers for all the studied properties due to its fineness, higher porosity, presence of calcite and increased asphalt film thickness of the mix. • Ageing resistance potential of hydrated lime mud was highest among the studied fillers due to its fineness and the presence of calcite. • Jarosite and hydrated lime mud filler significantly improved moisture, rutting, and crack resistance. • Hydrated lime mud possesses the highest ageing resistance potential among waste fillers, followed by jarosite, fly ash, and sugarcane ash. • Sugarcane ash filler showed the lowest cracking resistance and moisture resistance.