Properties of concrete with untreated and treated crumb rubber – A review

Crumb rubber has been used since sometime to improve the impact and toughness of normally brittle concrete. As the failure due to fatigue and impact loadings is a problem in normal concrete; the flexibility of the rubber aggregates could be the key to solve it. Even though there is a marginal reduction in the mechanical properties of crumb rubber concrete, this can be overcome by appropriate treatment of the crumb rubber aggregates. Methods, such as mechanical, chemical, thermal and microwave treatment could be used to treat crumb rubber aggregates to enhance their adhesion with the cement mortar. This is desirable since a significant positive impact on the environment could be achieved by utilizing crumb rubber from scrap tires in concrete resulting in the solution of their disposal problems and conserving the depleting sources of natural aggregates. Even though some literature on the properties of crumb rubber concrete is available, there is a need to evaluate methods to overcome the deficiencies of crumb rubber concrete. This paper is a state-of-the-art review on the mechanical, durability, thermal, and acoustic properties of concrete incorporating untreated- and treated-crumb rubber. The beneficial treatment methods have been categorized. It is hoped that this review will encourage the use of crumb rubber concrete in the construction of infrastructure and form a basis for further research on this material. The use of crumb rubber concrete will lead to a sustainable utilization of a waste material, leading to environmental protection and conservation of depleting sources of natural aggregates.