Including rubber

New WRAP (Waste & Resources Action Programme) funded research has demonstrated that crumb rubber from waste tyres can be successfully incorporated into retread compounds for road truck and earthmover tyres at much higher inclusion rates than was previously understood to be viable.

The research indicated that with crumb rubber incorporated at levels of up to 40 per cent, the tyres suffered no reduction in durability or performance when compared to the industry standard. In some cases the new compounds even showed an improvement in performance when compared to the control materials – they cured 20 per cent quicker and proved more durable.

Re-treading is considered to be one of the more preferable and effective methods of re-using worn tyres as the process effectively doubles the life of a tyre; reducing the numbers of new tyres needed and minimising waste. It is hoped these findings will encourage growth of the tyre reprocessing market, positively impacting on the 48 million waste tyres generated in the UK each year.

The study trialled both truck tyres that were fitted to dual-drive axle tipper lorries and earthmover tyres, with a diameter of 1.6 metres, that were fitted to dump trucks.

The report details how the process of surface polymerisation enables high rates of rubber from waste tyres to be successfully included in retread compounds - a process which had not been thought possible until now.

'The UK produces around 130,000 waste tyres every day so testing and developing new outlets for tyre-derived rubber material is a priority for the industry. This study provides reassurance for users that high percentages of rubber crumb can successfully be incorporated into retread compounds for truck and earthmover tyres without compromising the tyres’ performance. It is especially encouraging that some of the new compounds produced during this trial have been shown to offer benefits over the original compound,' said Steve Waite, Project Manager for Tyres at WRAP.

'A green sustainable solution now exists for the tyre industry; Surface Repolymerisation is the breakthrough that the waste tyre industry has always sought. This complete new approach now offers tyre companies a new ‘true green’ material that has both economic and environmental benefits in its future use,' added Robin Pegden, Managing Director of Envirogen Technologies, the company involved with the re-polymerisation technology used in the trial.

The full report on the trial and research findings is available free from the WRAP website and can be downloaded at www.wrap.org.uk/tyres.