Mechanical behavior of recycled concrete made with different construction waste aggregates

Purpose This paper aims to investigate the feasibility of using recycled aggregates from construction and demolition waste, specifically marble, brick and recycled concrete, as sustainable alternatives to natural aggregates (NA). The study quantifies the impact of these specific recycled materials at substitution ratios of 0%, 50% and 100% on the workability of fresh concrete and the mechanical properties (compressive and flexural strength) of hardened concrete. Design/methodology/approach An experimental approach was used to compare the mechanical behavior of ordinary concrete with concrete containing recycled aggregates. Seven concrete mixes were produced using varying ratios of natural aggregates (NA), marble aggregates (MA), brick aggregates (BA) and Recycled Concrete Aggregates (RCA). The mixes were batched in accordance with EN 206–1 using the Dreux-Gorisse method, maintaining a uniform particle size fraction (8 / 15 mm), a constant cement dosage of 350 kg/m3, and an effective water/cement ratio of 0.46. Workability was evaluated via slump testing, while compressive and flexural tensile strengths were determined using cubic and prismatic specimens at 7, 14 and 28 days. Findings The results indicate that marble aggregates enhance the mechanical performance of concrete, whereas complete substitution (100%) with RCA or BA significantly degrades strength. However, incorporating a 50% hybrid replacement blend markedly improves mechanical performance compared to full-replacement mixes, demonstrating a viable pathway for structural applications. Originality/value Unlike many studies that focus on a single type of recycled material, this study compares the mechanical behavior of four materials with different mineralogies under identical experimental conditions, as well as a hybrid system combining two types of aggregates. It also introduces a hybrid aggregate replacement strategy that substitutes natural aggregates with recycled aggregates to achieve the dual objectives of effective waste valorization and improved recycled concrete properties.