Abstract:

The global construction industry stands as one of the most resource-intensive sectors, consuming vast quantities of raw materials, energy, and water. Among these, concrete remains the most extensively used man-made material, second only to water in global consumption. Its widespread application, however, comes at a significant environmental cost. The extraction of natural aggregates from quarries and riverbeds has led to large-scale depletion of non-renewable resources, land degradation, and ecological imbalance. Concurrently, the generation of construction and demolition waste (CDW) has escalated with rapid urbanization, resulting in severe waste management challenges and unsustainable landfill burdens. In this context, the utilization of recycled aggregates (RA) derived from processed demolition debris presents a promising pathway toward sustainable construction. Replacing natural coarse aggregates (NCA) with recycled coarse aggregates (RCA) in concrete not only reduces the strain on natural resources but also offers a practical solution for the effective reuse of CDW. This study, titled “Use of Recycled Aggregates in High-Strength Concrete: A Sustainable Approach for Modern Construction,” investigates the mechanical and durability performance of high-strength concrete (HSC) incorporating varying proportions of RCA. The experimental program was designed to evaluate the influence of RCA replacement levels (0%, 20%, 30%, and 50%) on compressive strength, chloride ion permeability, and overall durability. The concrete was mixed to achieve a characteristic compressive strength of M60 using Ordinary Portland Cement (OPC 53 Grade), natural river sand as fine aggregate, and RCA obtained from crushed M30-grade concrete waste. A constant water–cement ratio of 0.35 was maintained across all mixes. Tests were conducted at 7, 14, and 28 days to assess the development of mechanical strength, while the Rapid Chloride Penetration Test (RCPT) evaluated the permeability resistance of each mix after 28 days of curing. Results indicate that up to 30% replacement of NCA with RCA yields compressive strengths comparable to those of conventional concrete, with a marginal reduction of approximately 8–10%. Beyond this threshold, a noticeable decrease in strength and density was observed, primarily attributed to the higher porosity and weaker interfacial transition zone (ITZ) of the recycled aggregates. Durability assessments revealed that chloride ion permeability increased with RCA content; however, the RCPT results for 30% RCA mix remained within the “low permeability” category as per ASTM C1202 standards. From a sustainability standpoint, the inclusion of 30% RCA led to a 15–18% reduction in CO₂ emissions, 30% conservation of natural aggregate resources, and a measurable decline in embodied energy compared to traditional HSC. The study thus demonstrates that with appropriate quality control, surface treatment of RCA, and optimized mix design, recycled aggregates can be successfully incorporated into structural-grade high-strength concrete without compromising performance or longevity. Overall, this research underscores the vital role of recycled aggregates in achieving circular economy objectives within the construction sector. It provides evidence-based insights into the technical viability, environmental benefits, and potential policy implications of adopting RCA as a mainstream material for sustainable and resilient infrastructure development.

Keywords:

Recycled aggregates, high-strength concrete, sustainability, compressive strength, durability, chloride permeability, circular construction

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