Evaluation of Recycled Polymer as an Alternative for Highly Modified Bitumen

Abstract

This paper presents a laboratory study of highly modified bitumen (HiMB) incorporating styrene butadiene styrene (SBS) and low-density polyethylene (LDPE). Due to economic and environmental concerns, there is a demand for developing sustainable alternatives that include reclaimed polymers. Recycled LDPE plastomer was mixed with base bitumen and virgin SBS elastomer to produce the HiMB binders. The total polymer concentration was fixed at 7% by weight of the HiMB binder. The morphology of the HiMB binder was captured by optical microscopy while the physical behavior and the rheological properties were measured by the traditional asphalt tests and the multiple stress creep recovery (MSCR) test. The addition of reclaimed LDPE polymer increased the softening point and complex modulus, and reduced the phase angle and tenacity. The HiMB binders showed limited improvement in storage stability and elastic recovery when mixed with recycled LDPE. All HiMB binders met the specification requirement of non-recovery compliance for the E-grade asphalt and provided a satisfactory solution in the MSCR test. The HiMB binder was shown to derive its strength and elasticity from a three-dimensional SBS network. At the same time, reclaimed LDPE exhibited a rigid and tough system which could be resistant to deformation. Flexible and resilient HiMB binders could result when the combination of SBS and LDPE polymers was used for modifying base bitumen. Test results showed the potential of using recycled LDPE polymer as a promising alternative to commercial styrene-butadiene polymers as it improved the viscoelastic properties of the neat bitumen.