Transforming e-waste into sustainable concrete: enhancing mechanical and durability properties with surface-treated plastic aggregates

Plastic aggregates (PAs) obtained from e-waste were investigated as sustainable replacements for natural coarse aggregates (NCA) in concrete. The characteristics and performance of concretes containing three types of PA – untreated plastic coarse aggregate (PCA), sand-treated plastic coarse aggregate (PSA) and plastic coarse aggregate treated with silica fume (PSFA) – were evaluated. In the concrete mixes, the levels of NCA replacement were 10%, 15% and 20%. Extensive experiments were conducted to determine the concretes’ densities, mechanical properties and durability. The concrete made with 20% PCA achieved superior workability and decreases in fresh and dry densities of up to 5.4% and 6.3%, respectively. The use of PSA and PSFA enhanced the compressive strength and split tensile strength of the concrete because of the improved adhesion of these treated aggregates with cement paste. The mix with 20% PCA demonstrated a 90% reduction in heat conductivity with enhanced thermal insulation. The mix with 20% PSFA resulted in a 17% increase in thermal resistivity and a 22% reduction in thermal conductivity 22%. Meanwhile, the mix with 20% PCA displayed the best sulfuric acid resistance with minimum weight loss. It was concluded that PSA and PSFA can be used as suitable substitutes for NCA in concrete, but further adjustment is needed to find the optimum balance between strength and sustainability.