Asphalt production is not a silver bullet for Australia’s waste problems, says James Ng. But the Project Manager for State Asphalts NSW says that doesn’t mean it can’t be a part of the solution.
He says a new line installed at the company’s South Nowra asphalt manufacturing plant will enable the ongoing use of recycled crushed glass as a partial replacement of aggregates and sand in asphalt mixes.
“Asphalt is a large market,” James says. “Because it takes a mixture of liquids and solids we can use a lot of different materials, but we shouldn’t be competing with the highest end use for recovered materials.
“If you’ve got an amazing piece of clear glass, put it back into making a clear glass bottle. If you’ve got a quality piece of plastic pipe, make it back into a pipe.
“Asphalt production should be part of the solution to divert waste from landfill or as a secondary use.”
The State Asphalts NSW South Nowra project received more than $244,000 from the NSW Environment Protection Authority Civil Construction Market Program, which provides grants to organisations to divert construction and demolition waste from landfill, and post-consumer recyclate such as glass, paper and plastic through reuse, recycling, and industrial ecology projects in the New South Wales civil construction sector.
State Asphalts NSW has used recycled products including recycled asphalt pavement (RAP), rubber and plastics in its product designs for some time, and while James says RAP is now considered standard, many asphalt manufacturing plants are not designed to have multiple recycling lines.
He says State Asphalts NSW recognised a need to invest in plant equipment that would allow it to diversify the range of recycled products it could use in asphalt production. The company identified glass as one waste stream that didn’t have a good end market.
At the time, Shoalhaven City Council was commissioning its crushed glass recycling plant, established to deal with a mountain of stockpiled glass waste.
James says there was a synergy with what Shoalhaven and State Asphalts NSW were trying to achieve.
“Shoalhaven was the first in the recycled market to actually ask, what do you need?” he says.
“They went through several stages to get the size, cleanliness and wash lines right at their glass recycling plant to ensure a product that almost mirrored virgin excavated material.
“They’ve got the glass fines to a point that we’re confident it’s not going to negatively impact the asphalt.”
The amount of glass in asphalt mixes can be up to 2.5 per cent in wearing course mixes, and 10 per cent in lower course mixes. There are State and Federal trials with much higher glass percentages.
James says State Asphalts NSW is aiming to bring all of its asphalt products produced at South Nowra up to the regulatory maximum for recycled glass content.
He says that with the support of Shoalhaven, they have overcome two of the main obstacles to using recycled content – quality assurance and a regular supply.
“We’re selling an engineering material, it needs quality assurance,” he says. “It’s what the civil construction market demands.
“Construction materials need to be strong enough to do their thing. You can’t compromise the quality just because there’s a large supply of recycled material.
“Until now it’s been a critical point. If there are variances or changes in the raw material supply, we can’t continuously engineer our product around it.”
James says the first production trial of asphalt at State Asphalts NSW’s new glass line in September went without a hitch.
Buoyed by the success, the company, in partnership with Shoalhaven, aims to build on the variety of recycled materials it can use.
It is also leading a Commonwealth CRC-P partnership to look at how packaging waste can be developed into infrastructure materials.
James says the company is keen to continue its sustainability journey and engineer in-house facilities that minimise the environmental impact of its operations.
“Even if it’s a small part, it’s incredibly motivating for all our team to be part of a tangible recycling solution,” he says.
For more information, visit: www.stateasphalts.com.au
