Abstract: The objective of this study was to improve the mechanical, environmental and economic performance of a new asphalt concrete with residual aramid fibres and conventional binder, with the aim of matching or surpassing the performance of asphalt concrete with polymer-modified binder. To achieve this goal, this research was developed in five main chapters: firstly, the mechanical performance of the mixtures was evaluated in the circular road simulator; secondly, the abrasion resistance of asphalt mixtures was studied by means of the steel brush test; thirdly, the recyclability of the experimental mixture was assessed by replacing 50?% with RAP (with residual aramid fibres) using traditional laboratory tests such as Marshall, Water Sensitivity, Wheel Tracking, Modulus and Fatigue; fourthly, an environmental impact study was conducted from a cradle-to-grave perspective; and fifthly, a cost-benefit analysis of the experimental asphalt concrete was carried out. The results indicate that, in terms of surface wear evaluated in the circular road simulator, the experimental mixture, made with 50-70 binder and residual aramid fibres, performs better than reference mixture made with 50-70 binder without fibres (typically employed in Spain), but slightly worse than reference mixture with PMB modified binder without fibres. Then, with respect to the steel-brush test, abrasion resistance seems to depend mainly on the binder type, asphalt made with polymer modified binder showing the best results. At the same time, recyclability analysis suggests that the use of 50?% RAP is feasible, although the experimental mixture shows higher stiffness and lower fatigue performance. Finally, in environmental and economic terms, asphalt concrete with recycled aramid fibres improves on the reference asphalt concrete typically used in Spain, but is still inferior to asphalt concrete made with polymer-modified binder.
