Benchmarking the embodied environmental impacts of the design parameters for asphalt mixtures

Abstract

For the full abatement of road construction emissions and the enhancement of green public procurement, the embodied environmental and social impacts of asphalt mixture typologies must be better understood. Therefore, the aim of this paper was to explore the environmental impact of five key asphalt mixtures classes (dense-graded, gap-graded, open-graded, porous and stone mastic) and the influence of their design parameters. This was achieved through carrying out 160 life-cycle assessment case study simulations to explore the upper and lower bounds for key design parameters, such as granulometric curve, filler and bitumen content, and filler and bitumen type. Results identified dense-graded (AC) and stone mastic (SMA) mixtures were the most impacting, per tonne, and gap-graded (BBTM A) and stone mastic to be the most impacting per unit depth. Porous mixtures had the largest impact range. Higher traffic classes also would experience an increase in emission levels, due to the need for better, or modified, binders. Future work would require the application of these results to case study projects, to better understand current mixture and construction impacts and the influence of durability.