Performance Evaluation of Asphalt Concrete Incorporating Polyethylene Terephthalate-Coated Steel Slag Using Marshall Stability, Indirect Tensile Strength, and Moisture Susceptibility Tests

This study evaluates the performance of asphalt concrete incorporating steel slag aggregates coated with recycled polyethylene terephthalate (PET). The aim was to enhance adhesion between aggregate and binder while addressing environmental concerns related to waste management. Laboratory testing was carried out to assess Marshall stability, indirect tensile strength, and tensile strength ratio, which are commonly used indicators of strength and moisture resistance in asphalt mixtures. The results showed that PET coating enhanced binder-aggregate bonding, resulting in higher stability, which indicates an improved resistance to plastic deformation and moisture damage compared to uncoated slag mixtures. Among the tested combinations, the mixes containing 20% slag with 10% PET and 30% slag with 15% PET demonstrated the most balanced performance. These mixes achieved greater durability while maintaining satisfactory strength values, indicating that PET-coated slag can serve as an effective partial replacement for natural aggregates in asphalt concrete. The study also highlights that the approach can help reduce reliance on natural stone, lower construction costs, and promote recycling of industrial byproducts and plastic waste. This contributes to more sustainable pavement practices while addressing issues of waste disposal and environmental degradation. The findings suggest that PET-coated steel slag can be considered a practical and resource-efficient material for asphalt mixtures. The research not only adds technical evidence to the growing interest in waste-based construction materials but also provides guidance for adopting such methods in developing countries, where cost and sustainability are critical factors.