Effect of Softer Binder on Bituminous Mixture Containing Reclaimed Asphalt Pavement (RAP) Material

Abstract

AbstractBecause of the increasing cost of bitumen and aggregate, there is increasing interest for utilizing higher rates of Reclaimed Asphalt Pavement (RAP) material in new hot mix asphalt (HMA) as a result of the gainful effect on the climate, preservation of energy, and saving natural resources. Yet these RAP materials are highly stiff due to the aged binder present in it, making untimely damage to the pavement. To adjust the negative effect of the aged RAP binder, a softer binder is a reasonable choice that reestablishes the properties of the aged binder. This exploration focused on the impact of suitable grade softer binder on the HMA mixture containing RAP. All mixes were designed according to Superpave specification (Ninitial = 8, Ndesign = 100, and Nfinal = 160 gyrations) by considering the 12.5 mm nominal size of the aggregate. RAP utilized in HMA mixes at four varying percentages, such as 0%, 30%, 40%, and 50%. The suitable grade of the softer binder is controlled by the blending chart technique. Performance properties of these mixes were assessed by volumetric, indirect tensile strength (ITS), moisture sensitivity, and rutting. Later these outcomes constrated with the performance of the control mixture containing PG70-X binder. Results of the laboratory experiment show that ITS value increases, as RAP quantity increases. TSR of the mixes lies above the acceptance criteria of 80%. On the other hand, resistance to rutting increasing with RAP. In light of the results, it might be concluded that the softer binder has a significant effect on the RAP mixture, and RAP up to 50% may be used for the construction of bituminous pavement.KeywordsRAPSofter binderVolumetricMoisture sensitivity