The role of calcined clay in lower-carbon cement
Calcined clay is a supplementary cementitious material (SCM) that can be used to partially replace conventional cement clinker to deliver two potential advantages. First, SCMs do not release process carbon dioxide emissions when made. Unlike clinker production, which unavoidably releases carbon dioxide from the raw material, clay calcination primarily produces water as a byproduct. Therefore, if an SCM such as calcined clay replaces a portion of carbon-intensive cement clinker, it commensurately reduces the carbon footprint of the final cement or concrete product. Second, SCMs have the potential to further reduce the cost and environmental footprint of the cement product, as they may reuse waste products and/or require lower temperatures to make.
As the cement and concrete industry seeks to reduce emissions and costs, interest in SCMs is increasing. The use of typical SCM materials, however, such as fly ash from coal power plants and slag from steel production, are expected to become increasing restricted as these industries transition to lower carbon intensity processes.
Clay offers a highly prospective alternative SCM material. It is widely available, particularly in regions with high cement demand but limited access to conventional SCMs, and can be processed at lower temperatures than conventional cement. The potential to utilise locally available clay resources as an SCM therefore offers a solution for regional cement markets to reduce their costs and emissions while maintaining supply chain resilience.
Beyond its use as a supplementary cementitious material in conventional cement blends, calcined clay also has the potential to support next-generation lower-carbon cement formulations. These include blended cements that utilise higher proportions of calcined clay to replace clinker, further reducing the carbon intensity of the cement product. While widespread adoption of next generation cements will depend on evolving standards, specifications and market acceptance, these formulations represent an additional mid- to long-term opportunity for calcined clay.
Benefits of the Calix technology for calcining clay
Calix’s platform technology is being applied to the production of calcined clays to support the development of lower-carbon cement and concrete products using locally available clay resources. Calix’s indirect heating technology aims to deliver multiple potential benefits for calcined clay production.
- Lower carbon-intensity and cost: The Calix technology enables full electrification of the energy requirement for clay calcination, including the potential for flexible operations compatible with variable renewable energy sources. Calix’s electric calcination technology can therefore avoid carbon emissions from energy use and unlock access to periods of low-cost electricity to further reduce the carbon intensity and cost of the product.
- Improved product quality: Control over the process environment enabled by Calix’s indirect heating approach can prevent oxidation, thereby providing control over the product colour.
- Improved production efficiency: For suitable clay deposits containing both kaolinite and carbonate phases, precise control of temperature and atmosphere may allow selective activation of the kaolinite while preserving carbonate minerals, with the potential to reduce energy consumption and improve product quality.
Commercial production with Green360 Technologies
In March 2026, Calix announced an agreement with Green360 Technologies (GT3) to produce commercial quantities of calcined clay at the Calix Technology Centre in Bacchus Marsh, Victoria.
Under the agreement, clay feedstock from GT3’s kaolin operation in Pittong, Victoria is toll processed using Calix’s CFC15k flash calciner. The arrangement is designed to support the commercial production of calcined clay products for use in lower-carbon cement and concrete applications.
Commercial concrete milestone with Boral and Smartcrete CRC
Further progress was achieved through a collaboration with Boral, which announced the successful completion of a field trial as part of the M1 Pacific Motorway extension in New South Wales, Australia. The trial involved a commercial concrete pour using a calcined clay cement blend. The milestone demonstrated the use of calcined clay produced by the Calix technology in a commercial concrete application and represented an important step in deploying the material for broader use within the Australian construction sector.
The trial built on successful product development and a collaborative R&D project involving Calix, Boral, UTS, Transport for NSW and the SmartCrete CRC to assess the application of calcined clay in cement and concrete products.
Continued progress in calcined clay
Together, the GT3 toll processing agreement and Boral / Smartcrete concrete trials demonstrate continued progress in the development and evaluation of calcined clay products for the construction sector.
The work forms part of Calix and Leilac’s efforts to develop multi-pronged and lowest cost solutions to future-proof cement making. Alongside enabling the production of calcined clay as an SCM, the core technology continues to be developed to reduce fuel emissions and costs, and to capture the remaining unavoidable carbon emissions in conventional cement production.
Calix and Leilac continue to provide material testing, engineering services and commercial production capabilities to support its partners to develop lower cost and lower carbon cement, including supporting growing demand for calcined clays as SCMs.
