Evaluation of High-Temperature Rheological and Aging Characteristics in Asphalt Binders Modified with Recycled High-Density Polyethylene and Recycled Polypropylene

Because of extreme global temperatures driven by climate change, the vulnerability of asphalt pavement to heat-induced damage has become a major concern given increasing traffic loads. Traditional asphalt binders oftentimes do not meet the demanding standards for withstanding this condition. As a result, the use of recycled plastics in asphalt road construction has gained popularity because of its potential performance improvement, sustainability, and cost-effectiveness. This study investigates the impact of recycled high-density polyethylene (rHDPE) and recycled polypropylene (rPP) on the high-temperature rheological properties of asphalt binder throughout its service life. A comprehensive evaluation was conducted to assess the rutting resistance, elastic response, deformability, stress sensitivity, and aging susceptibility of modified binders at high temperature. The findings reveal that the addition of rHDPE and rPP to asphalt binders enhances rutting resistance, as evidenced by improved rutting parameters and rutting failure temperatures. The analysis of nonrecoverable creep compliance and percent recovery also showed improvement in elasticity and resistance to permanent deformation of the modified asphalt. Although rHDPE and rPP-modified asphalt did not meet the criteria for elastomeric polymers, a trend toward improved elastic response was observed with aging. Additionally, the result of the aging index showed that though increased stiffness is observed as asphalt-aged, rPP-modified asphalt is more susceptible to short-term aging but exhibits more stable performance during service life compared with the rHDPE-modified asphalt.