Are recycled and low temperature asphalt mixtures more sustainable?

ABSTRACT Innovations are necessary to achieve reduction of both CO2 emissions and use of fossil materials during construction and maintenance of roads. In this research, life cycle costs and environmental product indicators were used to investigate the consequences of the strategic decision of the Dutch national road administration Rijkswaterstaat to use “green” porous asphalt top layers. Asphalt with recycled content turned out to have 4%–5% lower life cycle costs than the reference mixture and caused 12%–17% less CO₂ emissions. Low temperature mixes were estimated to cause 5%–10% less environmental impacts than the reference, but the costs increased with a few percent due to the addition of rejuvenators. Life time expectancy is relevant for the outcomes of the comparison: if the sustainable asphalt mixtures would have a two year shorter life time, the environmental and cost impacts would overshoot the reference impacts. Suggestions for further research are 1) to monitor lifetime of sustainable pavements, 2) to update this study when more information is available, and 3) to investigate cost and environmental assessment of other sustainable asphalt solutions.