Title: Evaluating the properties of concrete pavements containing crumb rubber and recycled steel fibers using response surface methodology

Abstract

Stockpiles of discarded tires are a global concern. Since tire incinerating results in severe air pollution, reusing tires as tire rubber particles can reduce environmental pollution. A recycled tire, including rubber and recycled steel fiber, can be introduced in cement concrete. This study aimed to investigate the effects of crumb rubber and recycled steel fiber on the conventional concrete pavement’s short- and long-term performance. The impact of crumb rubber (Cr) (0–20%) and recycled steel fiber (F) (0–0.5%) on the compressive, splitting, and flexural strength, as well as abrasion and freezing– thawing resistance of concrete, was evaluated through response surface methodology (RSM). The results indicated that fiber’s addition to the concrete mix had a remarkable influence on flexural strength in low content and enhanced post-cracking ductility of rubberized concrete. Furthermore, incorporating crumb rubber as fine aggregate led to a reduction in the abrasion resistance and increased sensitivity to freezing–thawing in the presence of saline solution. According to optimization results, the most appropriate way to benefit from the desirable characteristics of rubberized concrete while minimizing the crumb rubber inclusion’s adverse effects is through the addition of fibers into the concrete mixtures.