Optimizing mechanical properties of green concrete using recycled tire waste and pozzolanic additives: A sustainable approach for construction

The growing accumulation of waste tires and the high CO₂ emissions from cement production—nearly 8 % of global emissions—pose major environmental challenges. Billions of tires are discarded annually, and their non-biodegradable nature creates long-term pollution risks. This urges the construction industry to seek sustainable alternatives. This study develops eco-friendly concrete by integrating recycled tire rubber, steel fibers, polypropylene fibers, and micro-silica. These additions enhance performance while addressing waste and carbon footprint concerns. Rubber powder (3 %, 5 %, 7 % by weight), recycled steel fibers (0.1–0.5 % by volume), and polypropylene fibers (0.2 % by volume) are combined with micro-silica to improve mechanical properties. Results show that rubber reduces compressive strength by up to 89.7 % (R7: 6.83 MPa vs. control: 66.60 MPa). However, it increases ductility and energy absorption by 19.1 %, making it suitable for seismic-resistant applications. Micro-silica and steel fibers enhance matrix cohesion, with the S5 mix achieving 69.67 MPa, which is 4.6 % higher than the control. Genetic algorithms and artificial neural networks (RMSE = 2.36 MPa) aid in optimizing mix designs. An optimal blend contains 3.79 % rubber powder and 0.2 % polypropylene fibers. This formulation reaches 67.20 MPa at 115.92 USD/m³ —0.8 % lower than conventional concrete—while maintaining CO₂ emissions at 358.57 kg/m³ . This is comparable to standard concrete (356.35 kg/m³). The approach repurposes waste tires, reduces costs, and sustains performance. By combining recycled materials with computational modeling, the study offers a high-performance, eco-conscious concrete solution. The results support circular economy principles and provide a practical, sustainable alternative for resilient infrastructure development.