Strength, durability, and impact behavior of recycled aggregate concrete with polypropylene aggregate

Abstract

Massive consumption and production of plastic is expected to have a significant environmental impact in the near future. Plastic waste from landfills can be refined and recycled as aggregates in concrete through subsequent processing. Several studies have already been conducted using plastic scraps as aggregate in concrete. However, more research is needed before it can be incorporated into structural concrete. Therefore, this study aims to investigate the static and dynamic behavior of concrete made with polypropylene plastic aggregate (PPA) obtained from waste plastic materials. Natural coarse aggregate (NCA) and recycled concrete aggregate (RCA) are partially replaced with PPA in this study and drop impact tests are performed after the samples are exposed to room and elevated temperatures (200 °C and 400 °C). PPA replacement percentages are 0, 5, 10, and 15 %. The drop impact test is performed on both cylinders (150 mm × 63.5 mm) and beams (100 × 100 × 500 mm) specimens. Different mechanical and durability tests are also investigated. The impact energy decreases by up to 68 percent as the PPA percentage increases at room temperature. Furthermore, when the specimens are heated to 200 °C or 400 °C, the impact blows are significantly reduced (6–13 no). After being heated to 200 °C and 400 °C, the 15 percent NCA replaced cylinder loses 87 percent and 91 percent of its impact energy, respectively. In terms of mass loss, the control cylinder has a higher loss than the PPA cylinders, indicating that the presence of PPA in concrete causes less damage. In terms of mechanical properties, the 5 percent PPA-based concrete outperforms the control. Depending on the concrete age and coarse aggregate types, a 5 % PPA content increases compressive strength by up to 11.6 percent. In terms of durability, the water absorption tendency increases with increasing PPA content, and all-natural PP concrete (NPC) and recycled PP concrete (RPC) exhibit moderate to very low chloride ion penetrability. Overall, it is proposed that 5 % PPA be used with NCA and RCA for structural applications.