Durability Evaluation of Sustainable Concrete Overlay Reinforced with Recycled and Manufactured Steel Fibers

The durability of concrete pavement overlays is crucial for maintaining long-term performance. This study investigates the durability of concrete incorporating recycled steel fiber (RSF) and a hybrid combination of RSF and manufactured steel fibers (MSF) for pavement overlay applications. Five steel fiber-reinforced concrete mixtures with different combinations of RSF and MSF, along with a reference concrete, were tested for abrasion resistance, corrosion resistance, high-temperature resistance, drying shrinkage, and freeze-thaw resistance. The results indicate that concrete solely reinforced with hooked end MSF exhibited superior performance in most durability assessments. Concrete containing RSF showed marginally lower or comparable durability to concrete reinforced with either hooked end MSF or straight MSF. Compared with concrete with straight MSF, RSF-reinforced concrete demonstrated 8.5% lower mass loss, a 36% lower reduction in cracked specimen flexural strength (CSFS) after 24 weeks of corrosion exposure, 15.5% higher drying shrinkage, and a 2.3% lower freeze-thaw durability factor. The concrete reinforced with a hybrid combination of RSF and hooked end MSF achieved durability performance similar to concrete containing either hooked end MSF, straight MSF, or their hybrid combination. Compared with concrete reinforced with hooked end MSF, concrete incorporating a blend of RSF and hooked end MSF showed a 32% higher mass loss, a 52% higher reduction in CSFS after 24 weeks of corrosion exposure, 7.3% higher drying shrinkage, and a 2.6% lower freeze-thaw durability factor. In summary, the findings highlight that RSF, either used alone or in combination with hooked end MSF, offers a sustainable and economic reinforcement for pavement overlays.