Hopes a new eco-friendly concrete can rise from the ashes of coal power


Researchers are hoping a new concrete recipe that uses waste products will create jobs and a renewable industry for a town transitioning away from coal mining.

Key points:

• The cement’s main ingredient is fly ash, a by-product of coal-fired power stations
• The mix incorporates 80 to 90 per cent of recycled products and reduces carbon emissions by up to 80 per cent compared to standard concrete
• It’s hoped the new product could create jobs in Collie, in WA’s south west

A team from Murdoch University in Western Australia has developed the concrete and dubbed it, ‘Colliecrete’, as the recycled products hail from the regional WA town of Collie. Laboratory assistant Ramon Skane said the aim was to incorporate as much waste as possible.

“Colliecrete concrete can use up to 80 to 90 per cent of recycled material as its cement component,” he said. The main waste product is fly ash, a by-product from coal combustion, but the design can also sustain bauxite residue from alumina mining and recycled aggregate.

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Hendrik Gildenhuys and Ramon Skane have created a concrete mix from a range of recycled products.

“These materials are waste; they have no purpose,” said Mr Skane. “We’re giving it a whole complete new life. We’re converting a waste to a resource.”

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Fly ash is a by-product from coal combustion and the main ingredient of Colliecrete.

Recycling waste and reducing emissions

Concrete is one of the most used building products in the world, but it is also a large source of greenhouse gases. A study in 2018 by global think tank Chatham House estimated cement was accountable for about 8 per cent of the world’s emissions.

But this concrete can create up to 80 per cent less emissions.

“The reason conventional concrete is so carbon intensive is because the cement that is used; all the raw materials have to be heated up to 1000 plus degrees,” said Mr Skane. “The cement that we use can be made anywhere at room temperature.”

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Like other geopolymer cement, Colliecrete is less carbon intensive.

A bright future, with a few hurdles

Colliecrete is a form of geopolymer concrete – which commonly uses fly ash as a main ingredient in its cement.

Geopolymer concrete has been developed in other areas of Australia and has been used in projects from pavements to airports.

Professor Greg Morrison, from the Curtin University Sustainability Policy Institute said the use of alternative, environmentally friendly products is emerging in the building industry.

“There’s a big potential to use different types of mixes for concrete to reduce greenhouse gas emissions and, or, to use other types of building technologies instead of concrete,” he said.

Professor Morrison said while the future is bright for the development of geopolymer concrete, there are still hurdles. “The question is, will it go to scale,” he said.

“That’s always the issue when you have very large companies that produce cement and concrete at very low cost.

“So I think that’s the challenge, but I think it’s a wonderful idea.”

Eco-concrete is becoming more popular as people turn to sustainable building products.

A new industry born out of the ashes

Collie was chosen as a home for the new concrete due to its abundance of fly ash.

The town has been burning coal for almost 100 years, which has created a large stockpile of the waste product.

Bluewaters Power Station, a privately run coal-fired power station in Collie has provided the researchers with fly ash samples for their testing.

“We’ve also supplied them with the data from our ash analysis,” said the station’s Stephen Deonck. “They’ve used that to create their mix or their particular mix that works well with our fly ash.”

The power station produces about 600 tonnes of fly ash every day which is currently trucked back to the coal mine and buried. Mr Deonck said it was fantastic to see a use for the waste product.

“If we can use fly ash and lock it up into useful products, then it can only benefit the community going forward,” he said.

Like many towns across Australia, Collie has begun to transition away from coal as the energy grid becomes more reliant on renewable energy sources.

It means the region is looking for new job-creating industries, and, eventually, an end to fly ash production.

But Ramon Skane is not concerned. “Once the power stations close down we can use the fly ash that’s been stockpiled over 60 plus years in the pits,” he said.

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Every day about 600 tonnes of fly ash is trucked from the power station and buried.

Solid jobs for the future

So far the researchers have made smaller scale concrete pours, with the largest at one cubic metre. But Collie Shire President Sarah Stanley can see the potential.

“The Colliecrete project is exciting because it ticks all of the boxes for sustainability in terms of new jobs, new employment opportunities, environmentally friendly industries, and it’s also really great for our community,” she said.

Ms Stanley said a business case estimated the product could create between 30 to 80 jobs. “The potential is limited really only by our imagination,” she said.

While the Colliecrete team is slowly scaling up the pours to test larger blocks of concrete, Ramon Skane is already looking to the future.

“Eventually we can use this for any concrete application. Freeway barriers … it could be used for buildings,” he said. “It could be used for anything that concrete can be used for right now.”

From a story by Kate Stephens, ABC South West WA – Posted Sat 18 Sep 2021