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A flexible approach with Fulton Hogan

Fulton Hogan’s wet blended crumb rubber asphalt is set to be used in a variety of road infrastructure projects.

Fulton Hogan is pushing the envelope when it comes to including crumb rubber asphalt in infrastructure projects of varying scales nationally.

According to Tyre Stewardship Australia, 450,000 tonnes, or 56 million passenger tyres reach their end of life nationally, with some of these tyres often ending up in landfill.

Tyres can take centuries to decompose, meaning waste tyres pose a significant threat to the environment. This growing issue has resulted in tyres being listed as one of three priority waste streams by the Federal Government.

The use of recycled tyres in road construction has been a popular method internationally for decades, through the form of crumbed rubber asphalt and modified binders.

Fulton Hogan has developed crumb rubber products for more than 30 years.
Fulton Hogan has developed crumb rubber products for more than 30 years.

Crumbed rubber asphalt and binders feature varying percentages of tyre components, predominantly gathered from motor vehicles. 

The uses and variety of options for the market was previously limited. But thanks to collaboration and a push from both government and the private sector, including companies such as Fulton Hogan, has opened the door for a greater volume of crumb rubber asphalt use.

Fulton Hogan has more than three decades worth of experience in crumb rubber binder production, for both spray sealing and asphalt mixes.

Nick Canton, Regional Manager – Fulton Hogan Infrastructure Services – Southern Region, says the company has vast experience in the development and utilisation of crumb rubber modified binders. He says this knowledge has led to additional research into new blend types.

“We’ve been using crumb rubber to modify spray seal binders for number of years,” he says. “In doing so, we identified the value in the modified properties, and how this could be adopted into asphalt.”

“We are continuing to innovate and explore solutions to our clients and communities’ waste and environmental problems. We are constantly exploring how we can use repurposed materials to increase specific performance characteristics across all our product range.”

Fulton Hogan has invested heavily to develop suitable infrastructure and established markets for the production of sustainable asphalts and spray seals across Australia.

In 2021-22 alone, Fulton Hogan manufactured over 16,000 tonnes of crumb rubber asphalt, helping to divert over 10,000 used tyres away from landfill. These crumb rubber modified asphalt products were used in road projects for most State Road authorities and many Councils including the City of Greater Geelong, Mornington Peninsula Shire, City of Greater Dandenong, City of Stonington, Central Coast, City of Lake Macquarie, Cessnock, City of Gold Coast and Moreton Bay Councils to name a few. 

Community and collaboration were important considerations for Fulton Hogan and the development of its crumb rubber asphalt.
Community and collaboration were important considerations for Fulton Hogan and the development of its crumb rubber asphalt.

A new blend

Around 10 years ago, Fulton Hogan identified the opportunity to incorporate wet blended crumb rubber modified bitumen into asphalt.

Over the course of the last two years, development on these products have formed part of Fulton Hogan’s ‘TyrePhalt®’ banner, now a standard product in Fulton Hogan’s vast offerings in the crumb rubber binder and asphalt space.

Chris Lange, Technical Manager – Fulton Hogan Infrastructure Services – Northern Region, says the wet blend method can result in a product with vastly improved fatigue resistance properties.

“In the dry blend process, the crumbed rubber is added into a batch plant or the drum of a continuous mix to partially replace a portion of the fine aggregate. Whereas in the wet blend method the bitumen is modified by blending the crumbed rubber and bitumen in a specialised blending plant,” Lange says.   

“The wet blend method enables quality assurance due to enabling the sampling of the resultant rubber modified binder and testing to ensure compliance to aspects like the softening point, viscosity and torsional recovery.”

In addition to reducing the number of tyres in landfill, wet blended crumb rubber asphalt can increase the fatigue resistance, binder viscosity, film thickness on aggregate and improved elastomeric properties.

Throughout the development of the wet blend asphalt, as well as TyrePhalt® products, Lange adds that Fulton Hogan received a greater level of knowledge on the properties and applicable materials for inclusion in production. 

“We learned that the dense grade rubber modified asphalt is a better selection than currently used asphalt with Class or Multi Grade binder – due to its increased film thickness and binder content – resulting in better fatigue and durability properties,” he says.

 On-going trials are evaluating the performance of wet blended crumb rubber asphalt.
On-going trials are evaluating the performance of wet blended crumb rubber asphalt.

Nick Canton says Fulton Hogan is always looking to incorporate repurposed materials such as RAP (Reclaimed Asphalt Pavement) and recycled glass sand to reduce the dependency on finite virgin quarried materials.

“We have completed projects where we have incorporated recycled glass, slag, RAP and tyre rubber whilst utilising warm mix technologies which in its own right can reduce our carbon intensity through energy use by up to 30 per cent,” Canton says.

“We have dedicated and accredited technical teams across Australia and New Zealand, focusing on research and design who are constantly working with our clients to address emerging issues and problems.”

One such expert is Johannes van Heerden Technical Manager, Pavement and Materials Engineering – Fulton Hogan Infrastructure Services – Western Region.

“For the Australian market sustainability is a main focus in this point of time. It’s obviously extremely important. It’s also about performance,” van Heerden says.

“These products are more durable and are highly impermeable, because the more bitumen you put in there, the better the workability. The more impermeable the asset, the longer it’ll last. So these aspects are fantastic.”

van Heerden adds that these factors help to reduce the long-term costs for users.

“If you can actually increase your pavement structural depth, and the distribution of strains and stresses, which would be lower, you can improve the structural capacity as well. You can reduce rehabilitation or pavement preservation treatment,” he says.

“Ultimately over a period of time this can reduce costs, not only for the cost of the product, but also the cost of the contract.”

Pavement in partnership  

One of the major benefactors of the use and development of wet blended crumb rubber was Tyre Stewardship Australia (TSA), who provided financial support in the form of infrastructure grants.

“These grants have enabled the investment into and development of two Fulton Hogan PMB blending facilities in Australia that would not have gone ahead otherwise,” Canton says.

“Having this infrastructure ensures we are able to produce these products locally and deliver high performing products to the local community. It also helps to ensure an additional avenue for an end-of-life use for recycled tyres in these areas.”

Fulton Hogan’s wet blended crumb rubber asphalt incorporates end of life tyres from a variety of sources, including motor vehicles.
Fulton Hogan’s wet blended crumb rubber asphalt incorporates end of life tyres from a variety of sources, including motor vehicles.

Grants and guidance from Austroads, the Department of State Growth, TSA and the Australian Flexible Pavement Association have helped to establish product trials in Tasmania to evaluate the performance of the binder against conventional materials.

Chris Lange says these types of trials aimed to provide an insight into the performance of the product in primarily LGA roads, environments with reduced traffic flows and associated pressures than metropolitan highways. 

“The main purpose was to give local councils an opportunity to assess the products which are known to provide longer lasting, more durable and fatigue resistant road surfaces,” Lange says.

“These projects will also give the road asset owners experience and knowledge to assist them with developing specifications to utilise this product into the future.”

Lange hails the trials as a success, saying the performance exemplified the wet blend’s ability to extend the life of the pavement layer.

“The increased viscosity enables greater film thicknesses and binder content to be achieved in the various mix types where it is incorporated. This increases the product durability and ability to withstand stressed imposed on the product due traffic and pavement movement,” Lange says. 

“It significantly reduces the thickness of the treatment to avoid reflective cracking – thus providing a substantial cost saving.”

Community and collaboration

On top of significant sustainability and performance benefits, the use and production of Fulton Hogan’s crumb rubber asphalt can also provide a boost for the local economy as well.

Nick Canton says Fulton Hogan carefully considers the wants and desires of the local communities in which we operate. No matter the context or size of the work at hand.  

“When we look at things like sustainability, the local component and ensuring we do things right the first time cannot be over looked. Not only working with those local clients individually, but collaborating with local businesses. This is about making sure that we›re using local repurposed waste materials wherever possible and for that specific community, driving real value through sharing our technical support and knowledge,” Canton says. “There’s a heck of lot of work that goes into that.”

“We as contractors have an immense part to play in ensuring the most sustainable future for generations to come. This has to be achieved by people and through collaborative partnerships.”

“It›s going to be a combination of step change and incremental enhancements to get us to where need to be. We also need to enable our clients to realise shared value of these initiatives. We as contractors need to consider ourselves custodians of these assets and endeavour to leave them in a better condition than how we find them whilst extending their life cycles, it›s not just about a win for today, it’s about the longer term. Ensuring we take the right approach and contribute collectively to these environmental challenges”

Dedicated national NATA accredited labs, as well as Australasian Technical and Research and Design teams helped to develop wet blended crumb rubber asphalt.
Dedicated national NATA accredited labs, as well as Australasian Technical and Research and Design teams helped to develop wet blended crumb rubber asphalt.

Canton says the realisation and confirmation of crumb rubber asphalt’s benefits has led to an increased demand.

“The product has been adopted and approved by most State Road Authorities including TMR, DTP, Mainroads, TfNSW and DSG. We’ve also seen wider adoption by Local Government Authorities also,” he says.

He adds that the industry should “watch this space”, with further developments and improvements in discussion for the wet blended crumb rubber asphalt, as well as a slate of upcoming projects which will see the use of the material.

“Our clients have differing needs, our communities have unique environmental issues we need to help in resolving where we can. We understand there is no single product to solve all problems and are continuing to alter and fine tune our products and services,” Canton says.

“We also understand this is just the tip of the iceberg and we’ll keep challenging ourselves to strive for continuous improvement. It’s part and parcel of what we do.”  

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