Effects of Reclaimed Asphalt Pavement on Hot-mix Asphalt

Abstract

Abstract This study examined the effects of reclaimed asphalt pavement (RAP) on the structural properties and performance of hot-mix asphalt (HMA) and the rheological properties of asphalt binder in the laboratory. As a first step, dynamic modulus (|E*|) and indirect tensile strength (ITS) tests were conducted on a set of HMA samples prepared with RAP and a set of HMA samples without RAP. The moisture susceptibility of samples with and without RAP was evaluated based on the |E*| ratio of wet to dry conditioned samples. Bending beam rheometer tests and direct tension tests were conducted on virgin binder, extracted binder, and RAP and aggregate mastics (mixture of binder and RAP and aggregate passing #200 to #50 sieves) to evaluate the low-temperature cracking. The results show that RAP materials caused an increase in |E*| and a decrease in ITS and had a negligible effect on moisture susceptibility. The RAP samples produced 15 % less permanent strain in |E*| testing than samples without RAP, which means that the RAP mixes were less susceptible to rutting. However, RAP mixed binder was more susceptible to low-temperature cracking as measured by the m-value (slope of the curve of stiffness versus time) and brittleness.