Eco-efficient roller-compacted concrete with recycled aggregates and fiber reinforcement

This study investigates the performance of sustainable roller-compacted concrete (RCC) mixtures incorporating varying proportions of fine and coarse recycled aggregates (f-CDW and c-CDW), waste concrete powder (CP), and polypropylene fibers (PPF). A total of sixteen mixtures were produced with zero-slump consistency, and water-to-binder (w/b) ratios ranged from 0.34 to 0.69 depending on recycled content and admixture levels. The control mixture without recycled inputs achieved the highest 90-day compressive and tensile strengths (48.98 MPa and 3.88 MPa), while recycled mixtures attained up to 37.22 MPa and above 3.0 MPa when ≤20 % CP and 0.25–0.50 % PPF were used. Increasing CDW and CP contents led to higher porosity (up to 4.33 %) and sorptivity (5.47 kg/m2), while oven-dry densities declined to as low as 2004 kg/m3. Durability was strongly influenced by composition: compressive strength losses ranged from 1.6 % to 28.2 % after magnesium sulfate exposure, 3 %–36 % in chloride cycles, and 20 %–71 % under 150 freeze–thaw cycles. Abrasion resistance varied from 0.94 % to 4.40 %, with optimal PPF levels improving surface performance and crack control. Excessive CP (≥40 %) and PPF (≥0.75 %) negatively impacted compactability and matrix integrity. From a sustainability perspective, using recycled aggregates and CP substantially reduced the environmental burden associated with cement and virgin aggregate use. Taguchi optimization helped identify eco-efficient mixtures that balanced mechanical performance with minimized environmental impact. The findings confirm that, with proper proportioning and material synergy, fiber-reinforced RCC incorporating recycled components can serve as a green, durable solution for infrastructure exposed to harsh conditions.