Characteristics of High-Strength Concrete Reinforced with Steel Fibers Recovered from Waste Tires
Authors: Elrefaei Ali E.M.M. , Alsaadawi Mostafa M. , Wagdy Wegdan 
Published: May 2023

A large quantum of vehicle waste is produced annually, of which tires pose the topmost hazard to the planet if not disposed of duly. only in Egypt, the approximately total number of tires generated annually could be about 10 million tires. Demand for tires is expected to increase each year, and in emerging economies, rising profits may increase the vehicles used and drive greater demand for tires. In 2017, approximately 287 million synthetic tires were produced in the United States and approximately 60 million tires were stored in warehouses . The disposal of those tires in landfills when they attain their end life and turn to waste is one of the essential difficult troubles inflicting numerous environmental problems . Therefore, some countries have passed laws to ban landfilling of tires and encourage the reuse of used tires for other purposes . Fiber Reinforced Concrete is a composite material composed primarily of concrete or mortar and randomly distributed with short, discontinuous, distinct fine fibers of defined geometry . The main fibers used in concrete include glass, rubber, steel, aramid and other synthetic fibers. The effectiveness of fiber-reinforced concrete depends on the nature and geometry of the fibers . One possible solution to recover waste steel fibers from the tire manufacturing process is to add them to concrete . In terms of various initiatives around the world to convert waste into new products, the purpose of this article is to quantify the steel fiber contribution of recycled tires used in the production of high-strength concrete. Steel fibers in recycled tires are extracted through mechanical recycling from used tires. In this process, rubber is crushed and granulated, iron is removed with a magnet, and cloth is removed with a vacuum. As a result, recycled tiers steel fibers are irregular in shape and come in a variety of lengths and diameters, but are highly resistant to bending because they are made of high-quality steel.. Recycled steel fibers can be used as cement reinforcing additives or reused as reclaimed steel. . However, fibers extracted from tires are contaminated with rubber particles (15-60% by weight), making them difficult to use directly for any purposeand a cleaning process is required. Also, due to its low density, it is expensive to transport. As a result, these textile fibers are often sent to landfills or incinerators. Adding steel fibers or other fibers to concrete can not only improve the toughness and ductility of concrete, but also improve the crack resistance and durability of concrete . Adding steel fibers to concrete can improve the concrete's deformation properties. Cracks in concrete develop slowly and the crack width is smaller than that of normal concrete. Concrete mixtures containing steel balls recovered from scrap tires had higher workability at less than 4%, and no significant decrease in compressive strength was observed at less than 2%. Although the effect of steel fibers on the compressive strength of concrete is negligible, the tensile and bending strengths increase significantly, but the resistance decreases when the fibers are mixed in an optimal ratio and increase slightly. There have been many studies on the use of waste tire steel fibers in conventional concrete. However, more research is needed on the effect of steel fibers from waste tires on high-strength concrete. In this study, the effect of steel fibers extracted from tires on high-strength concrete was investigated.