Repurposed plastic waste as a sustainable aggregate in bituminous mixtures

In bituminous mixtures, aggregate constitutes nearly 95 % of the material by weight. However, the growing demand for aggregate due to extensive construction activities has led to a scarcity of natural resources, necessitating sustainable alternatives that maintain performance while preserving the environment. This study explores the possibility of using artificial aggregate (AA) moulded from repurposed plastic waste, consisting of Low-Density Polyethylene (LDPE), High-Density Polyethylene (HDPE), Polyethylene Terephthalate (PET), and other single use plastic to partially replace granite aggregate in the design of bituminous mixtures. The Marshall specimens were prepared by replacing 2.5 %, 5.0 %, 7.5 %, and 10 % of granite aggregate with AA by weight. The results indicated that only the mixtures containing 0 %, 2.5 %, and 5.0 % AA met all volumetric and strength requirements. Thereby, the mixture performance studies were restricted to these mixtures only. The Hamburg Wheel Tracking Test results showed that 2.5 % and 5.0 % AA mixtures exhibited 12 % and 24 % lower rut depths respectively than 0 % AA. Mixtures with AA showed higher fatigue life than conventional mixtures at both mixture as well as binder scale. Morphological analysis performed using microscopic measurements verified the structural integrity of AA mixtures while leaching studies confirmed the environmental safety of bitumen-coated AA. The study concluded that 2.5 % AA can effectively replace granite aggregate in highway pavements with heavy traffic, while 5.0 % AA is suitable for use on city roads, offering a sustainable solution for plastic waste disposal. • Developed artificial aggregate (AA) from different types of plastic waste. • Studied influence of replacing mineral aggregate in bituminous mix up to 10 %. • Satisfactory volumetric properties can be achieved only up to 5 % replacement. • Rut depth reduced by 12 % (2.5 % AA) and 24 % (5.0 % AA). • Environmental safety confirmed using leaching studies.