Hybrid Fiber–Reinforced Concrete with Unsorted Recycled-Tire Steel Fibers.

In modern waste-management systems, an advantage is given to waste recycling and reuse, rather than to disposal. In the perspective of various initiatives taken worldwide in an attempt to convert waste materials into new products, the objective of this paper is to quantify contribution of unsorted recycled steel fibers from waste tires (RTSF) for use in the concrete industry. An environmentally and financially sustainable hybrid fiber–reinforced concrete (SHFRC), obtained by combining traditional components [manufactured steel fibers (M)] and unsorted RTSF is developed. This paper for the first time, demonstrates that by determining the optimal amount and ratio of fibers (M and RTSF), sustainable hybrid fiber–reinforced concrete (SHFRC) with equal or better properties compared to ordinary fiber-reinforced concrete with only M fibers can be prepared. At the same time, it is also shown that in the optimum quantity and correct ratio, synergy between RTSF and M fibers can be used even for preparation of SHFRC with deflection-hardening behavior. A crack width–deflection model for SHFRC with unsorted RTSF under four-point loading is proposed. [ABSTRACT FROM AUTHOR]