Laboratory Performance of Asphalt Mixtures Containing Recycled Asphalt Shingles and Re-Refined Engine Oil Bottoms

AbstractThe use of recycled materials, such as recycled asphalt shingles (RAS), has received considerable attention for its potential to decrease production costs and enhance the sustainability of paving operations. The objective of this study was to characterize the laboratory performance of asphalt mixtures containing RAS with and without re-refined engine oil bottoms (REOB) used as a recycling agent (RA). The RAS type used in this study was postconsumer waste shingles (PCWS). Five 12.5-mm asphalt mixtures were designed to meet Superior Performing Asphalt Pavements (Superpave) design criteria, with two containing no REOB and three containing various amounts. A suite of laboratory tests was used to ascertain the mechanistic behavior of the mixtures against major distresses. Laboratory testing evaluated the high-, intermediate-, and low-temperature properties of laboratory-produced mixtures using the Hamburg loaded-wheel tester (LWT), the semicircular bend (SCB) test, and the thermal stress restrained specimen test (TSRST). For the mixtures evaluated, results indicated that the use of REOB increased the recycled binder ratio, which adversely affected intermediate-temperature fracture resistance. Although the inclusion of 5% RAS and 5% REOB did not adversely affect low-temperature performance; TSRST results showed that as the percentage of REOB increased, low-temperature fracture performance decreased. On the other hand, rutting performance was comparable for the control mixture and the mixtures containing RAS and REOB.