Effect of recycled asphalt shingles on physical and chemical properties of virgin asphalt binders

Abstract

A laboratory study was conducted to evaluate the effect of recycled asphalt shingles (RAS) on the physical and chemical properties of virgin asphalt binders. A virgin asphalt binder meeting the Superpave specifications for PG 58-28 was mixed with varying percentages (0%, 5%, 7%, and 10%) of RAS binder recovered from post-manufactured asphalt shingles. The physical properties of the blended binders were measured using the rotational viscometer (RV), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) tests. The chemical properties of the binders were determined using the Fourier transform infrared spectrometry (FTIR) and gel-permeation chromatography (GPC) tests. The physical test results showed an improved resistance to permanent deformation (or rutting) with the addition of RAS, but higher susceptibility to early low-temperature (thermal) cracking. The results were inconclusive regarding the fatigue resistance of the RAS-containing asphalt binders. The chemical test results showed an increased level of aging due to the addition of RAS. Higher levels of aging were also observed following the use of the rolling thin film oven (RTFO) and the pressure aging vessel (PAV) tests. There was a modest increase in the level of aging in RTFO-aged binders due to the addition of RAS. However, significantly higher levels of aging were obtained for PAV-aged binders containing higher percentages of RAS, indicating that the addition of RAS will primarily impact the long-term performance of the asphalt binders.