The concrete industry is one of the major consumers of natural resources. Sustainable development aims to find alternative resources that could decrease the concrete industry's adverse effects on the environment and contribute to preserving natural resources. Vast amounts of waste tires accumulated worldwide are recognized as a good supplement for natural aggregates in concrete [1]. Shredded rubber is generally used as a substitute for coarse aggregate, irregularly shaped crumb rubber is used as a fine aggregate, and powdered rubber can be used as a filler, binder, or fine sand in concrete [2]. Concrete with recycled rubber has many advantages over standard concrete, such as more excellent ductility, lower thermal conductivity, and better resistance to freezing and thawing [3]. However, mechanical strength is generally reduced when the natural aggregates in standard concrete are replaced by rubber.

This study aimed to design load-bearing concrete in which fine aggregate was partially replaced by crumb rubber in the 5-20 % range by volume. Workability, compressive strength, density, dynamic modulus of elasticity, freeze-thaw resistance, and induced volume changes were comprehensively evaluated. The consistency of the rubberized concrete and the strength loss in the hardened state was compensated by adding a superplasticizer and silica fume. The results show that the modified concrete maintains its compressive strength and provides better freeze-thaw protection than standard concrete.