Utilizing construction and demolition waste in concrete as a sustainable cement substitute: A comprehensive study on behavior under short-term dynamic and static loads via laboratory and numerical analysis

This study explores the utilization of recycled concrete powder (RCP) as a sustainable alternative to conventional cement in concrete production, focusing on its impact on mechanical properties and impact resistance. Two series of concrete mixtures were prepared: one without and one with 0.5 % polypropylene fibers by RCP-replacing cement at varying proportions (0 %-50 %). Methodologically, the research involved both laboratory tests and predictive modeling using artificial neural networks (ANN) and fuzzy logic (FL). Laboratory evaluations assessed compressive, flexural, and tensile strengths under static loads, as well as impact resistance through repeated drop weight impact (RDWI) tests. Key findings reveal that RCP-incorporation of 15 % leads to negligible reductions in compressive, flexural, and tensile strengths, while higher replacements significantly decrease performance. The addition of polypropylene fibers notably improved mechanical properties across all RCP replacement levels, enhancing compressive strength by up to 23.65 % and flexural strength by 27.49 % at the upper limits of RCP substitution. Accurate predictions of 28-day compressive strength were achieved via the ANN model with an average prediction error less than 1 %. The study also validates that the Weibull distribution effectively describes the impact resistance of concrete mixtures, confirming the advantages of combining RCP with fiber reinforcement to achieve sustainable and high-performance concrete solutions.