Performance of Hot Mix Asphalt Concrete Modified with Plastic Waste from the Crushing Process of Polyethylene Terephthalate Bottles

Abstract

This study investigates the use of waste polyethylene terephthalate (PET) bottles to enhance the performance of asphalt concrete. The research is divided into two approaches. The first approach involves incorporating PET waste as an additive in the asphalt concrete mixture through the dry process at concentrations of 0.0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% by total aggregate weight. The second approach replaces a portion of the fine aggregate with PET waste in the asphalt concrete mixture at concentrations of 0.0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% by total aggregate weight. The studied PET waste is less than 2.36 mm. Asphalt concrete properties were tested following Thailand's Department of Highways (DOH) standards using the Marshall method. The performance of the asphalt concrete was evaluated through static testing (Indirect tensile strength, ITS) and dynamic testing (Indirect tensile resilient modulus, IT_MR). The results indicated that all mixtures met the Marshall property requirements of the DOH standards. Enhancing asphalt concrete with PET waste in both methods showed increased ITS and IT_MR, peaking at 0.6% PET content. In the first method, ITS improved by 19.70%, 28.05%, 45.21%, and 44.29% compared to unmodified asphalt concrete (0.0% PET) at testing temperatures of 25°C, 40°C, 50°C, and 60°C, respectively, while IT_MR increased by 156.83%. The second method demonstrated ITS enhancements of 13.39%, 19.87%, 29.10%, and 37.86% at testing temperatures of 25°C, 40°C, 50°C, and 60°C, respectively, with a 143.06% increase in IT_MR. These findings highlight the effectiveness of PET waste in both methods to improve asphalt concrete performance for high-performance pavement construction while addressing plastic waste reduction.