Independent trials have shown AusPozz™ high-reactivity metakaolin can significantly reduce the associated CO₂ emissions of concrete, whilst delivering substantial performance advantages

AusPozz™ is a high-performance metakaolin for use in low-carbon concrete and as a manufactured pozzolan it is approved for use in Australian concrete standards as a Supplementary Cementitious Material (SCM).

AusPozz™ is produced from Zeotech’s high-purity Toondoon kaolin deposit in Queensland and designed to give excellent pozzolanic reactivity when used with Portland Cement and Geopolymers. It can significantly reduce the carbon footprint of concrete and other cementitious products while providing a range of performance advantages.

Background

Metakaolin is a semi-calcined kaolin (produced typically at temperatures between 650°C and 750°C). Pozzolanic materials, like AusPozz™, have been utilised in building and construction for their technical benefits for over 2000 years.

The recognised performance benefits from using pozzolans in concrete are:

• Elimination of alkali-silica reaction (concrete cancer)
• Increased durability and compressive strength
• Reduced water absorption
• Reduced chloride penetration
• Increased sulphide resistance
• Efflorescence control
• Increased flexural strength
• Increased abrasion resistance

The conventional manufacturing process for high-reactivity metakaolin is expensive and produces a relatively high-carbon product, restricting its use to high-performance concrete applications.  Calcined clay (low-reactivity metakaolin) is widely used in concrete globally to reduce embodied carbon, but its effectiveness and potential market are limited by its performance. Zeotech’s ultra-high purity Toondoon kaolin feedstock enables a lower-cost flow sheet to produce AusPozz™, which is specifically designed for:

• Low embodied carbon;
• Economic viability; and
• Maximum reactivity

The natural 80-90% kaolinite content of Toondoon kaolin feedstock and simplified processing give AusPozz™ a competitive advantage with respect to these three key properties and offer tremendous decarbonisation opportunities for the construction industry.

Use of SCM’s is the most viable alternative to mitigate carbon dioxide emissions of the cement and concrete industries in the short term, and metakaolin is increasingly regarded as the most promising pozzolanic material for the future.

The cement and concrete industry accounts for approximately 8% of global emissions, and studies have shown that metakaolin can reduce the associated carbon emissions of producing concrete by up to 40%.

The Australian cement and concrete industry has declared its commitment to Net Zero carbon concrete by 2050.