การปรับปรุงการออกแบบส่วนผสมแบบมาร์แชลล์สำหรับแอสฟัลต์ชนิดผสมร้อนที่ถูกผสมด้วยขยะพลาสติกโดยวิธีการผสมแบบแห้ง

Abstract

The growing issue of plastic waste is a problem faced by many countries worldwide, including Thailand. The Material Flow Analysis (MFA) Study of Plastic Wastes in Thailand in 2021 found that landfills in Thailand are one of the peroblem with approximately 1.5 million tons of plastic waste each year, most of which are disposable plastic products. These plastics can be categorized into four main types based on their polymer structure: polyethylene (PE), polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET). As thermoplastics, these materials melt and become liquid when exposed to heat and solidify again when cooled, similar to the properties of asphalt cement. This makes it possible to incorporate plastic waste into hot mixed asphalt concrete using a dry mixing method with substitution. Plastic waste can act as a binding material in the asphalt cement. This article aims to provide a guideline for designing hot mix asphalt with plastic waste and to assess the performance of asphalt concrete containing plastic waste compared to conventional asphalt concrete. The study found that the appropriate amount of plastic waste can be determined in term of the plastic to binder ratio (PBR%) by weight. Additionally, the use of plastic waste in asphalt concrete reduced the amount of asphalt cement used compared to conventional asphalt concrete by 7%. The performance tests of asphalt concrete containing plastic waste mixture compared to the conventional type showed improved indirect tensile strength ratio 24.69%, resilient modulus 49.37%, dynamic creep resistance 59.88%, and indirect tensile fatigue test 27.73%. However, the skid resistance test using the British Pendulum Tester (BPT) method gave similar results to those of conventional asphalt concrete.