Reuse of Waste Tyre Fibres in Concrete—Fire-Spalling Mitigation

Abstract

This paper presents an experimental study investigating the effectiveness of reused tyre polymer fibres (RTPF) and reused tyre steel fibres (RTSF) in highstrength concrete to mitigate fire-induced spalling. Concrete is an inherently fire resistant material due to its low thermal conductivity and non-combustibility. Rapid advances have been made in the last few decades to improve the performance of concrete in large-scale structures (e.g. tunnels), which are driven mainly by factors (e.g. strength, cost and sustainability) other than fire safety. It has been found that modern high performance, high strength concrete is more vulnerable to fire-induced spalling. Many research have been carried out to improve the resistance of such concrete against fire-induced spalling, and the most common solution is the addition of polypropylene fibres (PPF). Each year in the EU, more than 3.5 million tonnes of tyres reach the end of their lives. These tyres comprise roughly 15% and 5% (by weight) steel and polymer fibre reinforcements, respectively. These fibres are then extracted during the tyre recycling process, but they are mostly landfilled or used as fuel since they are too agglomerated and contaminated by rubber to find alternative use. A series of concrete specimens with RTPF and RTSF were tested under thermo-mechanical loading. The results indicate the potential of replacing the manufactured fibres with these re-used ones to mitigate fire-induced spalling in concrete.