Mixed Design Optimization of Polymer-Modified Asphalt Mixtures (PMAs) Containing Carton Plastic Packaging Wastes

This study investigated the potential of reusing plastics derived from multilayered food carton recycling processes as a modifier for asphalt mixtures by dry process. Two types of plastics, one untreated and one pelletized, were added to a mixture containing neat asphalt binder using three different dry methods and in two different amounts (2 and 5% by weight of aggregates). The chemical and physical properties of the plastics were explored via differential scanning calorimetry (DSC) and laser diffraction granulometry. The fracture behavior of the polymer-modified asphalt (PMA) mixtures was evaluated via superpave indirect tensile (IDT) testing at 10 °C and comparative analysis with the reference and a mixture composed of the same aggregate curve and a traditional styrene–butadiene–styrene (SBS)-modified asphalt binder. The role of the plastic during crack initiation and propagation was investigated via microscopic analysis. The results show that plastics derived from carton recycling processes can be successfully used as an additive in asphalt mixtures via the dry method due to the compatibility between their melting and mixing temperatures. The shape of the plastics influences the cracking propagation and resistance of the mixture. Finally, the presence of plastics in the mixture reduces the proneness to accumulate deformation (about 50% less than the reference ones) and increases the failure resistance, leading to a better cracking response at intermediate temperatures.