Crumb rubber recovered from Australian off-the-road (OTR) tyres has been incorporated into asphalt on three Sunshine Coast roads, but a newly released life-cycle assessment shows that the environmental case will ultimately depend on how long those surfaces remain in service. Access the full report.
The National Transport Research Organisation (NTRO) assessment found that most of the crumb-rubber-modified treatments carried higher upfront greenhouse gas emissions than the conventional reference surfaces. Whole-of-life savings emerged only when the model assumed the modified surfaces would last longer and therefore require less frequent patching and resurfacing.
Depending on the site and treatment, the crumb-rubber asphalt required approximately 10% to 40% additional service life to reach emissions parity with its reference pavement. The trial roads, installed in 2024, have not yet operated long enough to demonstrate those extensions under real traffic and weather conditions.
That makes the report an important step in developing a potential market for Australia’s difficult-to-recover mining and agricultural tyres, but not the final verdict. The material has made it into the road. Its next task is to remain there long enough to deliver the modelled benefit.
From quarry tyres to local roads
The project brought together Tyre Stewardship Australia, Sunshine Coast Council, NTRO, Boral and several technical and industry partners. Large tyres from Boral’s quarry operations were processed into crumb rubber and used in asphalt treatments laid at Perlan Street, Railway Parade and Spalls Road on Queensland’s Sunshine Coast.
Across the three sites, NTRO examined eight pavement treatments, including conventional asphalt, polymer-modified asphalt and mixes using OTR-derived crumb rubber. The modified binders contained 18% crumb rubber, although this figure refers to the binder rather than the entire asphalt mix. In the complete mixes, crumb rubber represented approximately 1.4% to 1.9% of total asphalt mass.
The demonstration is significant because OTR tyres remain one of the most difficult parts of Australia’s end-of-life tyre challenge. Their size, weight and often remote location make collection and processing more complex than for passenger and truck tyres.
Road construction offers a potentially large domestic outlet. Local roads account for 77% of Australia’s road network by length, according to the Australian Local Government Association, including approximately 265,000 kilometres of sealed roads managed by councils. For tyre recyclers and the broader tyre industry, even selective use in suitable pavement programs could create demand for material that may otherwise be buried, stockpiled or disposed of in landfill.
The LCA, however, shows why using recovered rubber is not enough by itself to establish an environmental advantage.
A higher carbon cost at the start
NTRO calculated the greenhouse gas emissions generated by producing and transporting the materials, making the asphalt and laying each road surface. Material production was responsible for most of these upfront emissions.
Where the crumb-rubber and conventional surfaces were laid at a similar thickness, the crumb-rubber options generally started with higher emissions. This means they need to last longer before they can deliver a whole-of-life environmental benefit.
Some crumb-rubber treatments appeared more favourable because they used less asphalt. At Railway Parade, for example, the crumb-rubber surface produced lower upfront emissions than the reference surface, but it was also 15 mm thinner. A thinner treatment at Spalls Road produced a similar effect.
The study therefore does not show that adding OTR rubber by itself increases or reduces emissions. The treatments also differed in thickness, binder, aggregate, additives, production and construction. The clearest conclusion is that most of the crumb-rubber options carried a higher carbon cost when first laid, and their environmental case depends on whether they remain in service for longer.
Longer life changes the calculation
Road surfaces generate additional emissions every time they are repaired or replaced. NTRO therefore modelled what would happen if the crumb-rubber surfaces lasted longer and required less maintenance than the conventional alternatives.
Depending on the treatment, the crumb-rubber asphalt needed approximately 10 to 40 per cent additional service life to overcome its upfront emissions and reach parity with the reference pavement. Treatments using less asphalt reached that point sooner, but they were not direct like-for-like comparisons.
If the crumb-rubber surfaces last beyond those thresholds, the model indicates that they could produce lower whole-of-life emissions. If they do not, their higher starting emissions may not be recovered.
These results are projections, not measured performance. The report also contains conflicting figures for some parity points and maximum reductions, so its most favourable percentage should not be presented as a confirmed project result.
The durability gain has not been proven
The trial surfaces were laid in 2024 and have not been in service long enough to show whether they will last longer than conventional asphalt. The report’s service-life gains are assumptions used in the modelling, not results measured on the road.
Earlier laboratory testing produced encouraging signs that the crumb-rubber material may resist ageing, although it also identified handling issues that require suitable controls. Laboratory testing and early road performance cannot confirm how the surfaces will perform over several decades.
NTRO recommends continued monitoring and an updated assessment once long-term maintenance and service-life data become available. For councils, the conclusion is straightforward: the environmental benefit depends on the roads lasting longer and requiring less maintenance. If they do not, that benefit narrows or disappears.
What the trial does and does not prove
The trial proves that crumb rubber from large quarry tyres can be used in asphalt on council roads. It also shows how much longer the modified surfaces may need to last to overcome their higher starting emissions.
It does not provide a complete environmental or commercial assessment. The study focuses on greenhouse gas emissions and does not measure costs, other environmental impacts or the benefits of avoiding tyre burial and stockpiling, although these should be pretty obvious.
Location also matters. These tyres came from a quarry and were processed using infrastructure in South-East Queensland. Tyres recovered from remote mining and agricultural operations may require much longer transport distances, so the Sunshine Coast results cannot automatically be applied across Australia.
The long-term scientific results will undoubtedly be published when available, and continued monitoring will continue to determine whether the roads deliver the service-life gains assumed in the assessment. That uncertainty should not diminish the importance of the trial.
This project is a clear step in the right direction for OTR tyre recovery. It takes tyres that might otherwise be buried at mine sites and tests a circular pathway that turns them into useful infrastructure. If the roads achieve the expected durability, the environmental case will become stronger.
More broadly, the trial demonstrates a better direction for Australia: recovering, processing and reusing OTR tyres through traceable applications instead of leaving buried tyre stockpiles for future generations to manage. The roads still need to prove their long-term performance, but the objective is sound and the progress is real.
Sources
- National Transport Research Organisation, Life Cycle Assessment of Crumb Rubber Asphalt, version 3, 12 January 2026.
- Tyre Stewardship Australia, “New evidence strengthens the case for smarter roads”, 13 August 2026.
- Tyre Stewardship Australia, “Sunshine Coast’s Smarter Roads: OTR Crumb Rubber Results & LCA”, 22 April 2025.
- Tyre Stewardship Australia and Edge Impact, Life Cycle Assessment of Agriculture and Mining Off-the-Road Tyres, August 2024.
- Boral, “Big tyres making a big difference”, 20 September 2024.
- Boral, “Boral introduces Australia’s first crumbed rubber asphalt derived from OTR tyres”, 19 March 2025.
