Mechanical and high-temperature behavior of lightweight concrete with Zeytindalı and Bayburt stone waste

This study investigates the mechanical and thermal performance of sustainable lightweight concrete incorporating Bayburt stone as a natural aggregate and Zeytindalı stone waste, a marble-based industrial by-product, as a partial replacement. Six mixtures were prepared by replacing fine and coarse aggregates with Zeytindalı stone waste at 15%, 30%, and 45% by weight. Mechanical properties were evaluated through compressive strength, ultrasonic pulse velocity, and unit weight tests, while thermal resistance was assessed at 200 °C, 400 °C, 600 °C, and 800 °C. The results showed that Zeytindalı stone waste improved all key performance metrics. A 45% replacement of fine aggregate increased compressive strength by 20%, and the same level of coarse aggregate replacement led to a 25% increase compared to the Bayburt stone-based reference mix. Ultrasonic pulse velocity rose from 4.75 km/s to 5.30 km/s, indicating improved microstructural integrity. Unit weight increased from 1740 kg/m³ to 1880 kg/m³ with the highest replacement. Under thermal exposure at 800 °C, the reference mixture lost about 60% of its strength. In contrast, mixtures with 45% Zeytindalı stone waste retained 40–48% more residual strength. Statistical analysis confirmed that the increase in compressive strength between 30% and 45% fine aggregate replacement was significant ( p < 0.05). These findings confirm the potential of Zeytindalı stone waste for enhancing compressive strength, thermal resistance, and structural integrity in lightweight concrete. The study supports its use in fire-resistant and eco-friendly construction and contributes to broader waste utilization in the concrete industry.