Laboratory Performance of Asphalt Mixtures Containing Re-Refined Engine Oil Bottoms Modified Asphalt Binders

Abstract

The increasing use of hardened oxidized asphalt binders in recycling materials such as recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) has increased the need to use re-refined engine oil bottoms (REOB) as a recycling agent. However, conflicting conclusions on the effect of REOB on mixture performance have been reported in the literature. The objective of this study was to characterize the laboratory performance of conventional asphalt mixtures and mixtures containing REOB modified asphalt binders. Four 12.5-mm asphalt mixtures, containing 0%, 5%, 10%, and 15% REOB modified asphalt binders, were designed to meet Superpave design criteria. A suite of laboratory tests was utilized to ascertain the mechanistic behavior of the mixtures considered. Mechanistic tests were performed to evaluate the high-, intermediate-, and low-temperature properties and moisture susceptibilities of laboratory produced mixtures using the Hamburg Loaded-Wheel Tester (LWT), the Semi-Circular Bending (SCB) test, and the Thermal Stress Restrained Specimen (TSRST), respectively. Results showed that the addition of REOB did not adversely affect the rutting and moisture susceptibility of the mixtures. Similar low-temperature mixture performance was observed with an REOB dosage up to 10%, while a mixture with 15% REOB showed significantly reduced low-temperature cracking performance. A decreasing trend in SCB Jc with an increasing REOB content was observed indicating a negative effect of REOB on intermediate-temperature cracking resistance.