Recycled materials can cut costs, improve eco-credentials, and even prolong the life of local road networks, according to experts speaking at WALGA’s Transport and Roads Forum.

Speaking at the forum, Road Surfacing Solutions Owner Steve Halligan encouraged Local Governments to investigate use of crumb rubber in spray seals and asphalts.
 
Mr Halligan said crumb rubber was “low hanging fruit” when it came to improving environmental outcomes through diverting waste tyres that are difficult to deal with, to a useful product.  

“Crumb rubber in spray seals provides good bonding between the binder and stones, and avoids the stripping damage that otherwise occurs if rain falls in the first few days after the seal is completed,” he said.

“Spray seals including crumb rubber are less prone to flushing and have a longer life.”

He also spoke about Recycled Asphalt Pavement (RAP) as an effective way to reduce carbon emissions, noting most asphalt plants can include up to 15 per cent RAP in their mix.

Main Roads WA Materials Engineering Manager Les Marchant said the benefits of RAP needed to be pushed as contractors had not taken it up.

Crushed recycled concrete is another product available to road managers. 

“Currently more than 500,000 tonnes per year of crushed recycled concrete is available in WA,” Mr Marchant said.

“The State Government is keen to incentivise use with the aim of diverting 75 – 85 per cent of this away from landfill.”

Mr Marchant said emerging materials such as lithium mining by-product and incinerator bottom ash were being investigated for use in sub-base material and paving.

More than 1 million tonnes of lithium by-product is expected to become available as fine-grained material, possibly suitable for strengthening weak sub-base material.

The session wrapped up with a technical presentation from Civil Sciences and Engineering Principal Engineer Colin Leek, who described the substantial cost, time and environmental benefits of using in situ recycling. 

Foamed bitumen and emulsion stabilisation techniques are tried and tested recycling options.

Insitu recycling necessitates considerably shorter road closures during reconstructions, greatly reducing road user costs and construction related emissions, Mr Leek told the Forum.

View Les Marchant's Presentation here
View Steve Halligan's Presentation here
View Colin Leek's Presentation here