ARRB reviews the use of vehicle tyres in bitumen

The Australian Road Research Board (ARRB) is recommending further research into the use of passenger vehicle tyres in bitumen production.

ARRB Senior Professional Leader Guy Hand said Victoria’s Transport Department, formerly VicRoads, engaged ARRB to undertake a literature review on the subject.

“Using more end-of-life tyres in road construction is a known way to curb significant environmental challenge for Australia. The question is, how do we make that happen?,” Mr Hand said.

“One possibility is to engage the use of end-of-life car tyres.”

Most crumb rubber repurposed into Australian road construction currently comes from end-of-life truck tyres.

According to Mr Hand, truck tyres are predominantly composed of natural rubber, whereas car tyres contain a high proportion of synthetic rubber, as well as a nylon component.

“It is not well understood whether synthetic rubber will behave in bitumen in the same nature that natural rubber does,” Mr Hand said.

“No data from an Australian context is available to establish the compatibility and performance of synthetic rubber in bitumen.”

Mr Hand said the key objective of the review is to understand the current specifications of crumb rubber sourced by other road agencies, and the market availability and processing requirements of passenger vehicle tyres.

ARRB were additionally asked to identify the benefits and limitations of using passenger vehicle tyre crumb rubber as a road material in asphalt and sprayed seals.

“There are also barriers for recycling car tyres to be considered, such as economic, environmental and processing challenges,” Mr Hand said.

“With the Victorian Government’s focus on increasing the use of recycled materials in road construction, this literature review will help inform all stakeholders on the issues associated with the use of passenger vehicle tyres in bitumen.”

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Trial funded to turn sawmill waste into diesel and bitumen

Sawmill scraps and sawdust could soon be turned into renewable diesel and bitumen as a result of a $1.2 million feasibility study, funded by the Federal Government and Boral Limited.

The Australian Renewable Energy Agency (ARENA) has agreed to grant Boral with $500,000 towards the study, with Boral providing the remainder.

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The study will trial a mechanical catalytic conversion technology, developed by Spanish-based Global Ecofuel Solutions SL, along with initial design works for the full-scale plant, exploration of the regulatory challenges and development of the business case.

Boral will explore the technical and financial viability of establishing a biorefinery using this technology near its Herons Creek hardwood sawmill, near Port Macquarie, NSW.

If successful, the proposed biorefinery would cost around $50 million and could convert up to 50,000 tonnes of waste sawmill residue produces each year into transport grade diesel and renewable bitumen.

Sawmill residue, which includes sawdust, remnant woodchips, shavings and offcuts, is currently used for lower value uses such as landscaping and boiler fuel.

Boral consumes a large amount of diesel and bitumen, using around 100 million litres of diesel a year to operate its business in Australia. The company estimates the volume of timber residues should create around 16 million litres of diesel and 8000 tonnes of bitumen.

Boral Building Products Executive General Manager Wayne Manners said if the study was successful, the diesel and bitumen produced at the potential new biorefinery could eventually account for up to 15 per cent of Boral’s annual needs.

“The application of this technology has the potential to transform the way we use low value hardwood sawmill residues into a resource that could be highly valuable, not just to Boral, but to the industry more generally,” he said.

ARENA CEO Ivor Frischknecht said the project further shows that big businesses are increasingly moving towards renewable energy solutions.

“If this ground-breaking technology is successful, we hope to see a transition to similar biorefineries by other companies which have a waste stream in forestry or agriculture,” Mr Frischknecht said.

“The transport sector is a significant user of energy in Australia, with liquid fuels a key long-term energy source for heavy-vehicle road and air transport since they cannot readily be electrified.

“Bioenergy comprises a growing proportion of Australia’s energy mix, and this new technology could see residue from the production process be used to reduce Boral’s reliance on diesel and bitumen derived from fossil fuels,” he said.

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