Crumb rubber: spreading the message

Roads & Civil Works Magazine investigates the use of crumb rubber in pavement construction and maintenance in Australia, and the obstacles to its wider implementation.For the past two years, Tyre Stewardship Australia (TSA) has been driving change in how Australia utilises end-of-life tyres as a recycled product.

The organisation was formed under the National Product Stewardship Act to implement the national Tyre Product Stewardship Scheme, which aims to promote the development of viable markets for the significant number of discarded end-of-life tyres in Australia.

The scheme has been authorised by the Australian Competition and Consumer Commission and funded by a levy on the sales of new tyres sold by participating tyre manufacturers, which include Continental, Bridgestone, Goodyear-Dunlop, Michelin, Pirelli, Toyo and Yokohama.

According to the latest independent industry study, only 5 per cent of the 51 million end-of-life tyres discarded annually in Australia are recycled here. A large proportion of the other 95 per cent is burnt as a tyre-derived fuel in Asia, but, some are sent to landfill, stockpiled or illegally dumped.

Part of TSA’s goal is to provide an industry framework to reduce the environmental, health and safety impacts of this significant number of waste tyres each year.

Liam O’Keefe, Market Development Manager at TSA, says part of the goal in setting up TSA was to create a national body that could create a more direct industry approach to diverting these waste tyres from landfill. “It’s an issue that’s been chipping away for a long period of time, with comprehensive and concerted efforts to overcome the barriers,” he says.

“We have over 1200 accredited participants on board now, including the majority of Australian recyclers.” TSA’s membership is made up of all kinds of representatives across the waste tyre supply chain, including retailers, manufacturers and collectors, not just recyclers.

Turning these post-consumer tyres into material for reuse in road construction and maintenance is one area that TSA focused on, given it’s an established practice in Australia and in the likes of the United States. Tyre-derived crumb rubber (CR), for instance, has been used extensively in states such as Victoria in spray seals for the past few decades. However, TSA identified that it is a product not utilised to its full potential in nationwide road construction.

“Recycling of tyre crumb in roads is a major opportunity. It offers a significantly untapped market in Australia, particularly when compared with overseas,” says Mr. O’Keefe. “There hasn’t been a concerted effort to grow the market for CR as yet. However, there’s been more awareness and encouragement of using these waste products for positive outcomes.”

He says there is a hesitance to adopting such practice due to occupation health and safety risks, but also because of external industry factors. “A lot of bitumen suppliers also supply polymer-modified binders, and CR is essentially a modified binder,” he says, adding that little can be done to convince a company to not sell a particular product.

“The companies producing CR are pretty small in comparison,” he adds. The technical capacity is there for many of these firms, but the ability to produce the volume of product to meet market demand could be another obstacle. “Also, traditional CR road specifications in Victoria can require expensive and relatively complicated production methods.”

A major gap TSA is trying to fill is in the sharing of knowledge and experiences among states and territories. Mr. O’Keefe says a lot of the regions are working on different stages of implementation in regards to CR.

He says Victoria has led research into the use of CR in dense-graded mixtures, whereas Western Australia is developing work towards gap-graded specifications, and Queensland open-graded. “There has to be more extensive study of those practices within the environment and conditions of their state-specific use. This forms the basis for more extensive collaborations between states via organisations such as Austroads.

“Being a national organisation, we can work nationally to connect those dots. TSA is able to work collectively with all of those organisations across Australia to create a collaborative application of CR and support that work financially.”

With the allocation of research and development funding, TSA has partnered with ARRB, Sustainability Victoria, VicRoads, the Queensland Department of Transport and Main Roads, the Queensland Department of Environment and Heritage Protection and Australian Asphalt Pavement Association (AAPA), to undertake extensive research in this area. More specifically, the organisation is researching market barriers and finding ways to increase the use of tyre-derived products in the construction and maintenance of roads across the nation.

“CR definitely works, and it makes the roads stronger and better. If you can complete the circle – close the loop so that the tyres that have been used on the road are then used to make the road – then that is a positive.”

Mr. O’Keefe says there’s a lot of potential for the use of CR in wider pavement construction, but also in the rail industry. The material has been explored for use in the sub-base for the ballasts, which has proved effective in reducing vibrations and damage to the ballasts. “We’re also funding a project in Queensland with a company called Chip Tyre, BioAust Energy Pty Ltd and Sepuel Drill and Blast, which is looking at the benefits of using CR in the mining explosive industry, which could potentially consume tens of thousands of tonnes of Australian tyre-derived product.

“There is a history of CR on roads, so it’s easier to get traction in this area,” he adds.

Mr. O’Keefe says there is plenty of research to help support the use of tyre-derived CR in the construction and maintenance of Australia’s roads, but that information won’t be optimised until it’s put into practice and has an effect. The next stage is to engage and work with industry to overcome barriers to its use. “The research underpins the viability of the material, but if there are companies who can produce it more cheaply and safely then we’re interested in working with them.”

To help inform the industry and provide insight into the application and outcomes from CR in roads, TSA and AAPA have invited United States expert David Jones to talk about his experiences with the product at the 17th AAPA International Flexible Pavements Conference 2017, taking place in Melbourne this August.

Crumb rubber in action

For SprayLine Road Services, tyre-derived CR polymer spray seal has been the product of choice for a number of decades.

SprayLine is a VicRoads owned commercial provider of spray sealing and line marking services works across South-East Australia catering to contractors, municipal councils and state road authorities.

Trevor New, SprayLine State Operations Manager, has worked within the sector for more than 20 years and can’t recall ever not working with a CR-based polymer for spray sealing.

“CR has been used in Victoria in spray seals for years, well before I became involved. VicRoads and all the shires and councils allow for a tyre-derived product.”

He explains that the practice of using CR in spray seals has been the norm for Victoria and increasingly in other states.

“A large percentage of work done in Victoria would be CR rather than refinery blend,” he says.

Mr. New says refinery blend binders have been available for some time as an alternative product, but the past five years have seen industry in particular areas lean more towards CR.

SprayLine has been working consistently in South Australia with CR, aiming to help deliver the same benefits Victoria has seen with the tyre-derived binder.

“Costs differ for other states and companies, there are some special items of plant you need, such as blending facilities and some different technology in spray sealing, as well as the know-how and experience our guys have.”

He says some South Australian road contracts are beginning to call for CR spray seals.

“It’s better quality and better strength – SprayLine has consistently and successfully sprayed CR polymer for many years.

“We’re using 1000 tonnes of rubber that’s not going into landfills for a start. Many companies that don’t use it don’t see it as a user-friendly product, but we see it as really easy to work with, and it’s much better for reflective cracking.”

He says other companies may not use CR spray seal purely because they don’t know how to use it or they’ve had bad experiences using it.

“Because it’s different, there are companies, particularly through some states, that say it can’t be done. We’ve been doing it for 30 years and that’s the majority of what we do.”

Mr. New says the simplest answer may be to show those who aren’t familiar with the product, how it’s done. “The volume use of CR is relatively new to Queensland, but it’s been the binder of choice in NSW and Victoria for over two decades,” says Wayne Jupp, General Manager at NSW-based SRS Roads.

“It’s got a proven history in NSW and Victoria and It’s been widely used by us for years,” he says.

“It’s recycled, it’s really user friendly, it’s got far better elastic properties than conventional bitumen, it has superior crack mitigating properties, and it’s less susceptible to wet weather within a short placement time.

“It has a good shelf life and is easily transported, in fact we were carting 1500 kilometres for a job in March with no segregation when handled correctly.”

Mr. Jupp says there’s a perception that CR binders are not user friendly, however that is not the case, and it is the preferred modified binder of SRS Roads’ spray seal teams.

Part of the issue has been a gap in communication between states and territories on the subject of CR and its application, which TSA is increasingly filling.

“There is a real lack of technical transfer between the states,” says Mr. Jupp. “The fact is this is a wonderful product that’s great to use and a fantastic use of recycled tyres. You can incorporate 20 per cent recycled ground tyre and end up with a vastly superior binder.”

He adds that the granulated CR is comparable in cost to bitumen, which makes it cheaper than other modifiers.

SRS Roads has used the product for major projects such as the waterproofing of the Sydney Harbour Bridge for the first time in 80 years. Mr. Jupp says that this reconfirms Roads and Maritime Services’ confidence in CR.

“It’s the binder of choice for us from a management perspective, but it’s also the binder of choice for our guys on the road.”

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