Reduction of CO2 Emissions and Durability Assessment of Concrete Incorporating Recycled Aggregates, Steel Fibers, and Polycarboxylate Ether Nano-superplasticizers

Natural aggregates used in concrete are expensive, and their mining process is inherently disruptive to the environment. Additionally, the enormous volume of construction waste generated strains the ecosystems considerably. One promising alternative is addressing the challenges of concrete production and achieving environmental sustainability by producing recycled aggregates from leftover concrete. While Recycled Fine Aggregate (RFA) is rarely utilized in structural concrete, Recycled Coarse Aggregate (RCA) is increasingly recognized in structural applications and regulations. This research aims to replace the conventional fine and coarse particles in concrete with both RCA and RFA. To further enhance the performance of recycled aggregate concrete and promote sustainability, Polycarboxylate Ether (PCE) nano-superplasticizers were incorporated into the mix; they improve workability, reduce the water-cement ratio, and enhance particle dispersion, leading to improved strength and durability in concrete. The study specifically investigates the impacts of using 100% recycled coarse aggregate, 10% recycled fine aggregate, and steel fibers in place of natural aggregates. The results show increased slump value when recycled concrete aggregate (100% RCA and 10% RFA) replaces natural aggregate. Additionally, the combination of recycled materials (100% RCA with 10% RFA) and the addition of 2% steel fibers demonstrated superior durability properties compared to conventional concrete. This substitution not only enhances durability but also offers a more sustainable alternative to traditional construction practices.