Reusing Waste Food-packaging Plastic as Additive Modifier in Asphalt Mixtures

Packaging waste originated from the food-drinking sector is obtained through the maceration process, which allows the separation of aluminum foil, paper, and plastic. Due to this process, paper and aluminum foil can be reused, while plastic must be disposed. This paper aims to reuse the disposed plastic coming from this process as additive modifier to produce Polymer Modified Asphalt (PMA) mixtures. The research followed chemical and mechanical analyses. The chemical analysis evaluated whether the temperature of production of PMA was enough to melt the waste plastic and studied the chemical composition of the plastic used. Therefore, the melting points of the polymeric components were identified by the Differential Scanning Calorimetry (DSC), Fourier-transform infrared (FT-IR) spectroscopy, and X-Ray Diffraction (XRD) analysis assessed its composition. The mechanical analysis was performed by comparing the PMA mixtures, containing two percentages of reused plastic (5% and 10%), with two mixes prepared with 3.5% Styrene-Butadiene-Styrene (SBS) modified asphalt, using the SuperPave Indirect Tensile Test (IDT) at 10 °C. The DSC highlighted compatibility of the reused material in terms of melting temperatures. XRD and FT-IR results confirmed the waste plastic heterogeneity, presenting mainly Polyethylene (PE), High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Polypropylene (PP), Polyethylene terephthalate (PET), and Polystyrene (PS). The mechanical analysis showed that 5% plastic PMAs behave similarly to 3.5% linear SBS-modified mixes. However, 10% plastic content decreased PMA workability. In conclusion, it was possible to notice that a 10% increase of plastic in PMAs result in mixes prone to early failure and outside standard parameters.