UV curing study of semi-dense asphalt mixes with different sizes of copper slag – A sustainable rehabilitation and production strategy

Abstract

• Copper slag was used as a self-healing particle in asphalt mixes. • UV radiation by light bulbs was used as the healing process. • The copper slag showed self-healing rates of more than 40% • The slag size of 2 mm is presented as the optimum self-healing size. The environmental and service conditions exposed to asphalt pavements affect their rheological and performance properties, making them brittle material susceptible to cracking. One way to partially re-establish the mechanical properties of the cracked pavements is through binder runoff through the cracks in a capillary healing process. It is possible to incorporate conductive materials (electrical or thermal) in asphalt mixtures as additives or partial substitutes for the natural aggregate to maximize the efficiency of the self-healing process and induce a pseudo-Newtonian flow behavior in the binder. The present study evaluated the self-healing performance by UV radiation of asphalt mixtures incorporating copper slag (CS) in different sizes (2.00 mm, 0.25 mm, < 0.063 mm) as a conductive material (heat diffuser) in partial replacement of the natural aggregate. Likewise, the degree of ageing caused by the self-healing process was evaluated through the rheological characterization of the binder extracted after healing. All the CS mixes obtained self-healing rates in mechanical strength higher than 40 %, in particular, the 2.00 mm CS mixes with self-healing rates close to 60 %. The optimum self-healing temperatures for mixtures with CS sizes with higher thermal inertia are between 95 °C and 105 °C corresponding to 18000 s and 30000 s of healing, while for mixtures with CS sizes with lower thermal inertia the optimum self-healing temperatures are between 105° and110°C corresponding to self-healing times of 18000 s to 25000 s. It was not possible to determine an accelerated ageing effect in the asphalt mixtures due to the self-healing processes by UV radiation.