Upcycling of waste rubber using pelletized artificial geopolymer aggregate technology

The utilization of waste rubber as aggregates shows both environmentally friendly features and high cost-efficiency in construction, but may cause poor workability such as rubber flotation and agglomeration. To address the above issues, the pelletization method was adopted to produce rubberized artificial geopolymer aggregates (R-GPA), and the effects of different rubber modification methods and rubber contents were investigated through pelletization technologies, mechanical tests, X-ray computed tomography (XCT) and backscattered electron with energy-dispersive spectroscopy (BSE-EDS). Results showed that the combined modification with NaOH solution and silane coupling agent presented the most effective surface modification efficiency. According to microscopic analysis, rubber modification could effectively enhance the rubber-matrix interface. The produced R-GPA could thus possess an oven-dried particle density within 1500–1800 kg/m³, a water absorption of 7%–10.5%, and a pelletization efficiency over 98%, which provided a new insight into the value-added utilization of waste rubber and the promotion of artificial aggregate technologies.