Mechanical Properties of High Strength SCC Made with Hybrid Steel Fibers from Discarded Bead Wires

Abstract

The tire manufacturing sector occupies a significant portion of the global economy. The production of vehicle tires requires the utilization of different raw and processed materials. Steel beads are one of these main ingredients, used to reinforce the treads and sidewalls of car tires. In this study, the effect of incorporating steel fibers cut from discarded bead wire (DBW) during the tire manufacturing process on the rheological, mechanical, and flexural toughness of high-strength self-compacting concrete (SCC) was investigated. Four SCC mixes were prepared with four discarded bead wires, at volume fractions of 0%, 0.3%, 0.6%, and 1%. Four lengths of the discarded bead wires were used in the term of hybridization: 10, 20, 30, and 35 mm. These were mixed together, with each length comprising 25% of the total. Investigations of fresh and hardened concrete properties were carried out. The results showed that discarded bead wires affected the rheological properties of the high-strength SCC adversely, causing a considerable reduction in slump flow and passing ability and an increase in T500 and V-funnel time, and enhancing segregation resistance. On the other hand, the mechanical properties, such as compressive strength and splitting tensile strength were improved significantly with the inclusion of the discarded bead wire. Moreover, investigations of flexural toughness based on ASTM requirements were conducted. Overall, the presence of different lengths of the discarded bead wire helped to transfer the load from the cementitious matrix to the short fibers, and then to the long ones, leading to the enhanced energy absorption capacity of high-strength SCC.