Mechanical performance of asphalt base layers with high RAP content and recycling agents

With circularity in mind, adding reclaimed asphalt in new asphalt mixtures is a common practice. While aiming for higher recycling rates, the need for better control of the mixture performance increases. Recycling agents are often proposed to restore the properties of aged binders. This study investigates the mechanical performance of plant-produced hot mix asphalt for base layers with high reclaimed asphalt content and recycling agents. Two field test tracks, each containing a section with and without a recycling agent, were constructed to allow for long-term performance evaluation. Plant-produced asphalt mixture from all sections was sampled and compacted in the laboratory and subjected to various mechanical tests, including rutting, stiffness, fatigue, cracking and water sensitivity. Besides a lower indirect tensile strength, the overall results indicate a limited influence of the used recycling agents on the mechanical performance of the mixtures, particularly in terms of resistance to rutting and fatigue cracking.