Practical Rubber Pre-Treatment Approch for Concrete Use—An Experimental Study

Rajeev Roychand,Osama Youssf,Julie E Mills,Xing Ma,Rebecca J Gravina,Yan Zhuge

doi:10.3390/jcs5060143

Rajeev Roychand, Osama Youssf + Show 4 more

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https://doi.org/10.3390/jcs5060143

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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.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
7- and 28-day strength results of rubber concrete are attributed to the soft nature of the rubber particles and poor bond performance, as evident from a large gap in the interfacial transition zone between the cement paste and the rubber particles
This significant reduction in the compressive strength of rubber concrete is the key issue hindering its application in the construction industry

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. With extensive research spanning the last few decades, researchers have found various applications for increasing the utilisation rate of waste tyres, such as (i) tyre re-treading;. (ii) rubber-moulded products like flooring materials and shock absorbing playground mats; (iii) tyre pyrolysis to produce carbon black and oil/gas that can be used as a fuel;. (iv) geotechnical applications like sub-grade fill in roads and embankments [1,2,3,4]; (v) rubber modified asphalt pavements [5]; and (vi) in concrete, as a replacement for aggregates [6,7,8,9]

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