Practical rubber pre-treatment approch for concrete use—an experimental study

Abstract

There is a lot of ongoing active research all over the world looking for various applications of used tyre rubber, to increase its utilisation rate. One of the common research applications is to incorporate rubber into concrete as a partial replacement for conventional aggregates. However, due to its poor bonding performance with cement paste, the utilisation of rubber in concrete has been hindered to date. A cost-effective and time-saving rubber pre-treatment method is of great interest, especially for the concrete industry. Out of all the various pre-treatment methods, soaking rubber particles in water is the most cost-effective and least complex method. In addition, sodium sulphate accelerates the hydration reaction of the cement composites. This study looks at the effect of soaking crumb rubber in tap water for short (2 h) and long (24 h) durations, and the optimised duration was then compared with soaking the crumb rubber in a 5% concentration of sodium sulphate solution. Compressive strength, bond behaviour, and rubber/cement interfacial transition zone (ITZ) were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The results demonstrate that a soaking duration of 2 h provides much better performance in both the strength and bond properties compared to 24-h soaking. A further improvement in the 7-day strength was achieved with the rubber soaked in 5% sodium sulphate solution for 2 h, providing a more practical and economical rubber pre-treatment method for concrete industry use.