Strength and Microstructural Behavior of Sustainable Concrete with Varied Proportions of Recycled Fine Aggregate from Construction and Demolition Waste

Recycled fine aggregates (RFAs) encompass inorganic particles derived from the crushing of building and demolition waste, constituting an environmentally sustainable source for the concrete industry. This study explores the integration of construction and demolition (C&D) waste-based RFAs in concrete, aiming to reduce carbon emissions and promote eco-friendly construction practices. The RFAs, obtained from aging concrete structures, contribute fines to the concrete mixture, and their viability is assessed in this research. The investigation encompasses strength and microstructural analyses of RFA-based concrete blends with varying replacement percentages (20%, 40%, 60%, 80%, and 100%). The comprehensive evaluation spans 7 and 28 days of water curing, with particularly promising outcomes observed up to a 40% replacement threshold. The optimal performance is identified at the 40% RFA replacement, justifying the applicability of RFAs as an alternative fine aggregate. Microstructural studies conducted through a secondary electron microscope (SEM) specifically for the 40% RFA replacement substantiate the particle packing effect and corroborate the experimental findings. The findings underscore the sustainable potential of incorporating RFAs in concrete formulations, offering a pathway toward environmentally conscious and resilient concrete structures.