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Ishir Sindhu
Independent Researcher
India
Abstract
Concrete production is one of the largest contributors to global CO2 emissions, primarily due to cement manufacture. Incorporating industrial by-products such as fly ash and recycled coarse aggregates into concrete can reduce environmental impact while maintaining structural performance. This manuscript presents sustainable concrete mixtures developed using Class F fly ash and recycled aggregates obtained from demolished concrete elements. Mixture proportions were optimized through trial batches to achieve adequate workability and compressive strength comparable to conventional mixes. Laboratory tests included slump, compressive strength at 7, 28, and 90 days, and durability indicators such as water absorption and chloride permeability. Results demonstrate that up to 30% cement replacement by fly ash and 50% replacement of natural coarse aggregates by recycled aggregates yield compressive strengths within 90% of control mixes at 28 days and improved long-term performance at 90 days. Two case studies illustrate field applications in low-rise building components and precast pavers. The findings support the viability of fly ash and recycled aggregate concrete in noncritical structural elements, contributing to circular economy principles in construction.
Keywords
sustainable concrete, fly ash, recycled aggregates, compressive strength, durability
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