DEVELOPMENTS IN MECHANICAL STRENGTH, ACID RESISTANCE, SORPTION RESISTANCE, CARBON PERFORMANCE AND MICROSTRUCTURE OF CONCRETE THROUGH SPATIAL VARIATIONS USING DIFFERENT GRADES OF NORMAL CONCRETE

Cement production significantly contributes to CO₂ emissions and climate change. To reduce cement use and enhance concrete efficiency, this study investigates graded concrete (GC), composed of two different concrete grades (M30 and M20) using Portland Slag Cement (PSC) and Portland Pozzolana Cement (PPC) in a 1:1 spatial variation. The study also examines the partial replacement of PSC (40–70%) in M30 with fly ash (FA) and lime to improve sustainability and performance. Mechanical properties were assessed through compressive and tensile strength tests at 7, 14, 28, 56, 91, and 182 days. Durability was evaluated via acid and sorption resistance, while the ecological aspect was assessed through embodied carbon analysis. Results showed that GC outperformed conventional M30 concrete, even with 50% cement replaced by 43% FA and 7% lime. GC demonstrated a 33% reduction in embodied carbon compared to M30. Microstructural validation through scanning electron microscopy confirmed the improved performance. Overall, the findings highlight the potential of GC as a sustainable and efficient construction material, promoting the beneficial use of industrial by-products like FA.