Long-term performance of concrete reinforced with scrap tire steel fibers in hybrid and non-hybrid forms: Experimental behavior and practical applications

This study examines the potential impact of scrap tire steel fibers (SSFs) on concrete properties, focusing on longterm performance. The reuse of discarded tires in construction addresses the environmental challenge of tire disposal. While previous research has explored SSFs in concrete, long-term properties and practical implementation pathways of SSF-reinforced concrete are lacking. To address these gaps, this study assesses the influence of locally available SSFs from Bratislava, Slovakia, on concrete properties, specifically targeting the 120 day hardened properties. Locally sourced C20/25 concrete is used, incorporating SSFs in non-hybrid (single type of fibers) and hybrid forms (30% industrial hook end steel fibers "ISF"). SSF dosages range from 0.3% to 1.75% for non-hybrid fibers and 0.50% to 0.70% for hybrid fibers. Experimental properties, including elastic modulus (EM), compressive strength (CS), tensile splitting strength (SS), flexure strength (FS), residual flexure strength (RFS), linear shrinkage (LS), and water absorption (WA), are evaluated. The toughness and energy absorption capacity are demonstrated for SS and FS. The results indicate that the inclusion of SSFs enhances the EM and SS of SSF-reinforced concrete (SSFRC). Additionally, SSFRC exhibits reduced linear shrinkage compared to concrete without SSFs. Notably, the hybrid fiber concrete (HSFRC) shows superior performance, outperforming both ISF concrete and SSFRC in enhancing the considered properties. HSFRC exhibits promising potential for replacing ISF concrete in various civil engineering applications. However, further investigation is needed to evaluate the performance of HSFRC under extreme environmental conditions.