Integration of life cycle assessment into a decision support system for selecting sustainable road asphalt pavement mixtures prepared with waste

Purpose. A challenge that the road paving sector is facing concerns the achievement of highly performing bituminous asphalt mixture solutions that do not negatively impact the environment. New environmentally sound asphalt production and recycling technologies are becoming more and more widespread, but their practical application is still hindered by the lack of appropriate decision-making strategies by the administrations. In this study, innovative asphalt mixtures were compared through a novel multi-criterion and sensitivity analysis framework for selecting the best solutions. Methods. A new decision support system has been implemented to choose the best paving alternative between nine asphalt mixtures containing different marginal materials for the binder and base layer of a flexible pavement. The methodological steps taken to reach the definition of the optimal solution concerned (1) mechanical analysis of the designed asphalt mixtures by laboratory investigation, (2) calculation of life cycle assessment indicators using the ReCiPe method, (3) application of the ELECTRE method for the identification of the optimal solution on the basis of both mechanical and environmental performance considering a traditional weight vector, and (4) sensitivity analysis based on 27 different configurations of weight vectors. Results and discussion. The results of this work revealed that the hot asphalt solutions for the binder layer utilizing jet grouting waste and fly ash in substitution of natural fillers reached the best engineering and environmental performance, respectively. Between the asphalt mixtures for the base layer, the cold recycled asphalt containing reclaimed asphalt pavement and jet grouting waste reached, at the same time, the best environmental performance, the minimum value of permanent deformation, and the highest stiffness at 40 °C. The ELECTRE method and sensitivity analysis demonstrated that the purpose of jet grouting for making both hot and cold solutions is the best-compromise solution of environmental and mechanical performance. Conclusions. The proposed framework allows the quantitative assessment of sustainable road asphalt pavement solutions and fits the needs of several engineering fields where a trade-of between the mechanical and environmental performance of multiple construction materials must be established. Future development of this framework could include cost indicators to address the sustainability of the solutions in detail.