Performance evaluation of concrete manufactured with precoated recycled fine aggregates using supplementary cementitious materials

Abstract

In this study, fly ash and ground granulated blast-furnace slag were applied over fine recycled aggregates in layers of 0.2 and 0.4 mm. We then evaluated the resulting concrete with regard to freshness, mechanical properties, and durability. The fine recycled aggregates (coated and uncoated) were used to replace 25% of the natural fine aggregates in two water–cement (w/ c) ratios of 0.4 and 0.6. The coating of recycled aggregates with fly ash was shown to improve the workability of the concrete, regardless of the w/c ratio. Coating recycled aggregates with slag was shown to slightly reduce the workability of the concrete. A fly ash coating was shown to slightly increase the compressive strength of concrete, whereas a slag coating markedly improved compressive strength beyond that of the original concrete. Our results indicate that coating recycled aggregates with furnace slag is an effective approach to enhance the mechanical properties and durability of recycled concrete.