Performance of Asphalt Binders Modified with Devulcanized and Enhanced-Devulcanized Waste Rubber

Abstract: The devulcanization of tire rubber occurs when the material undergoes a mechanical, chemical, or chemo-mechanical process that partially or entirely reverses vulcanization. This industrial process aims at breaking the sulfur-sulfur crosslinks without significantly compromising the polymeric structure of the rubber, making this material more suitable for reuse or recycling. Adding devulcanized rubber (DVR) to neat bitumen has been demonstrated to achieve enhanced performance. However, the level of devulcanization and the chemicals added during the devulcanization process have a significant effect on the properties of the modified asphalt binder. With recent advancements in devulcanization techniques, enhanced DVR products are now available, offering new options for producing high-performing asphalt binders. In this study, different DVR products were used to modify a single neat bitumen and compare their performance against a conventional Styrene-Butadiene-Styrene (SBS) modified binder. Binders were lab-produced through subsequent high and low-shear mixing stages at high temperatures. Performance grading tests were conducted, followed by advanced high-temperature characterization using the Multiple Stress Creep Recovery (MSCR) test and intermediate-temperature performance assessment using the Linear Amplitude Sweep (LAS) test. Additionally, the storage stability of the binders was assessed through cigar-tube testing. The results were analyzed to evaluate how potential modifications to the initial polymer may affect the performance of the modified asphalt binder, presenting a case where enhanced DVR-modified binders could potentially replace conventional SBS-modified binders.