Green360 expands concrete platform with silica fume replacement as coal plant closures bite

Green cement materials company Green360 Technologies (ASX: GT3) has unveiled a second commercial product designed to replace silica fume in high-strength concrete, positioning the company to capitalise on a widening supply gap as Australia's coal-fired power stations shut down and traditional steelmaking declines.

The new product, MKX Ultra Fine (MKX UF), is engineered as a direct 1:1 replacement for silica fume - a key supplementary cementitious material (SCM) used in concrete mixes above 60 MPa (megapascals) - and expands Green360's MKX platform beyond its first product, MKX Calcined Clay (MKX CC), which targets fly ash and slag replacement.

Green360 says independent testing by the University of Melbourne has confirmed MKX UF delivers comparable 28-day concrete strength to silica fume at 60–70 MPa mix designs, with 24-hour strength exceeding 20 MPa against the 15 MPa minimum required for precast de-moulding.

The results open a path into high-performance applications including precast panels, bridge infrastructure and shotcrete.

The latest announcement comes as Australia faces what Green360 describes as a "looming supply cliff" for the SCMs that underpin modern concrete performance.

Fly ash, a byproduct of coal combustion, and slag, a byproduct of blast furnace steelmaking, are both declining in domestic availability as coal-fired power stations close and steel production methods shift.

Silica fume, produced as a byproduct of silicon metal smelting, faces similar constraints with reduced domestic production.

The supply pressure is already prompting action across the sector.

The South Australian Government has approved a $12 million concessional loan to Hallett Group for a project at Port Augusta's former coal-fired power station, which closed in 2016, aimed at processing up to 20 million tonnes of legacy fly ash into cement products.

The project could deliver a 60 per cent carbon reduction compared with conventional cement production.

Green360 executive chairman Aaron Banks says MKX UF addresses a critical gap in the market as traditional SCM sources dry up.

"For decades, the concrete industry has quietly relied on a hidden ingredient that most people have never heard of: Supplementary Cementitious Materials, or SCMs," says Banks.

"Materials such as fly ash from coal-fired power stations, slag from steel manufacturing and silica fume from silicon metal production have become essential components in modern concrete.

"While they are often discussed for their ability to reduce carbon emissions by replacing a portion of Portland cement, their importance goes far beyond sustainability."

Banks says SCMs improve strength, reduce cracking, lower permeability and dramatically increase the lifespan of concrete exposed to harsh environments.

"In many of the world’s most durable bridges, tunnels, ports, dams, and high-rise buildings, SCMs are not optional extras - they are fundamental to performance.

"The problem is that the industries that produce these materials are disappearing.

"Coal-fired power stations are closing, reducing the supply of fly ash. Traditional blast furnace steelmaking is being replaced by cleaner technologies that produce little or no slag.

"The concrete industry now faces a looming supply cliff. Demand for durable, high-performance concrete continues to grow, yet the materials that have underpinned its performance for the last fifty years are becoming increasingly scarce."

Green36 Technologies has produced more than 600 tonnes of MKX CC to date through a toll-treatment arrangement with Calix Limited's Bacchus Marsh facility in Victoria.

That two-year binding agreement provides up to 30,000 tonnes per annum of calcination capacity, with about $300,000 in capital improvements completed.

Green360 also holds a non-binding memorandum of understanding with global building materials giant Holcim for up to 4,800 tonnes per annum of MKX CC over an initial 12-month period.

A binding supply agreement is targeted within 90 days of the MOU's execution on 12 May this year.

Banks says the dual-product platform - MKX CC for fly ash and slag replacement, MKX UF for silica fume replacement - gives Green360 a broader addressable market across both standard and high-strength concrete segments.

"Without adequate SCM supplies, concrete producers face higher costs, reduced durability, shorter asset life, and increased dependence on Portland cement," he says.

"The consequences extend well beyond carbon emissions; they strike at the very heart of infrastructure quality and resilience.

"This is why materials such as MKX have become strategically important. Unlike fly ash, slag and silica fume, which are by-products of other industries, metakaolin is purpose-made.

Green360 says it is advancing further testing of MKX UF across additional mix designs and applications, with commercial discussions under way alongside the existing Holcim engagement.