Analysis of the influence of using recycled polystyrene as a substitute for bitumen in the behaviour of asphalt concrete mixtures

Roads play a crucial role in transporting people and goods and providing access to services; however, their construction involve harmful environmental impacts due to the carbon emissions stemming from their bitumen content. Under this premise, this research aimed at adding three different types of polystyrene (PS) wastes to asphalt concrete to substitute bitumen: General Purpose Polystyrene (GPPS) also known as Crystal Polystyrene, High Impact Polystyrene (HIPS) and Polystyrene from hangers (HPS). Hence, a reference Asphalt Concrete mixture (AC 16 S, named REF in the article) was designed and dosed for comparing it with the experimental mixtures in which bitumen was reduced by different percentages and replaced by polymers. Every sample was tested separately for comparison purposes, so that the addition of residual polystyrene was found to modify several mixture properties: there was an increase in voids content and a significant decrease in plastic deformations, whilst other characteristics remained in the order of magnitude of conventional values. Once the mechanical properties of the modified mixtures were validated, a Life Cycle Assessment (LCA) was undertaken to compare their environmental performance with that of conventional asphalt mixtures. The results achieved suggested that substituting part of the bitumen by polymers might reduce the environmental impacts of asphalt mixtures, taking into account the expected increase in their lifecycle provided by the presence of plastics. (C) 2017 Elsevier Ltd. All rights reserved.