The use of fired clay in the form of metatone or metakaolin (MK) as a pozzolanic material for mortar and concrete has received considerable attention in recent years. The construction industry is facing the crucial challenge of significantly reducing CO2 emissions. Cement production is one of the main causes of this, with around 650 kg of CO2 per ton of cement. In view of the global climate targets, the search for more environmentally friendly alternatives is more urgent than ever. Dorfner has already developed promising approaches with its DORKACOM® 50 and DORKAPUR® 100 metakaolins, which not only reduce CO2 emissions but also offer many advantages for the construction industry.

What is metakaolin?

Metakaolin is a highly reactive pozzolan that is produced by the calcination of kaolinitic clay at temperatures of approx.  800 °C, e.g. in a rotary kiln. This process converts kaolin into an amorphous aluminum silicate. Metakaolin is generally used as a mineral additive in Portland cement systems to improve mechanical properties, durability and longevity due to the silica and alumina it contains. Metakaolin is considered to be twice as reactive as most other pozzolans, e.g. based on fly ash, and is therefore a valuable additive for concrete/cement applications.

Metakaolin

Metakaolins differ in color, particle size and reactivity. Reactivity is measured using the modified Chapelle test, for example. The amount of slaked lime that can be bound by the metakaolin is determined here.

Other methods of reactivity determination are, for example, the measurement of the heat of hydration according to ASTM C1897-20, the chemically bound water according to ASTM C1897-20 or the reactive SiO2 according to DIN EN 197-1.

In addition to its use as an additive for cements, metakaolin is used in the production of building materials such as plasters, fillers, tile adhesives, mortar   etc. In fire protection applications, metakaolin improves fire resistance.

A growing market is the use in geopolymers. This geopolymer concrete has a very high resistance to acids and sulphates. Due to these outstanding properties, geopolymers are used as an alternative to Portland cement composites in various special applications, for example for refractory coatings, fibre-reinforced composites and for waste immobilization. Other examples of applications in agriculture include biogas plants, fermentation silos, slurry tanks and in wastewater and sewer construction as components for sewage treatment plants as well as pipes and manholes.

With DORKACOM® 50 and DORKAPUR® 100, Dorfner offers two innovative metakaolins from its own production.

Metakaolin DORKACOM® 50 from Dorfner: This product can replace up to 40% of conventional Portland cement. This leads to a significant reduction in CO2 emissions, as DORKACOM® 50 has a CO2 equivalent of 200 kg CO2 per ton. In addition, DORKACOM® 50 is particularly suitable for aesthetic applications due to its high whiteness property.

Metakaolin DORKAPUR® 100 from Dorfner: As a high-quality metakaolin, DORKAPUR® 100 offers the ability to significantly reduce CO2 emissions in the building material, as DORKAPUR® 100 has a CO2 equivalent of 350 kg per ton. It reacts with calcium hydroxide and water to promote the formation of calcium silicate hydrate and calcium aluminum hydrate, which improves the strength and durability of the concrete.

DORKACOM® 50 and DORKAPUR® 100 are 2 very light-colored metakaolins with high reactivity and particularly suitable for white applications in construction chemistry.

The use of metakaolin in the construction industry offers numerous advantages.

Environmental friendliness

The use of DORKACOM® 50 and DORKAPUR® 100 in cement mixtures enables a significant reduction in the ecological footprint. By dispensing with cement-based products, the construction industry can drastically reduce its CO2 emissions. Geopolymer concrete produced with metakaolin is particularly environmentally friendly as it does not contain any CO2-intensive cement components.

Improvement of mechanical properties

Metakaolin significantly increases the compressive strength of concrete and improves its durability. Studies show that the compressive strength and resistance of concrete to chemical attack and abrasion are significantly increased by the addition of metakaolin. This is particularly important for construction projects that are exposed to extreme conditions.

Extended shelf life and improved processing

The products DORKACOM® 50 and DORKAPUR® 100 are characterized by a long storage stability of over 12 months, which increases flexibility in application.

The global market for metakaolin is forecast to grow to 1.26 billion US dollars by 2030. The European market is also showing growth, with sales of 152 million US dollars, which is expected to grow to 225 million US dollars by 2028. Demand for metakaolin is particularly strong in China. (Source: worldwide: Strategic Market Research; Europe: Business Market Insights)

Overall, DORKACOM® 50 and DORKAPUR® 100 from Dorfner represent a decisive step forward on the road to a more sustainable construction industry. Their environmentally friendly properties and the many benefits they offer the construction industry position them as attractive alternatives to conventional Portland cement. Dorfner goes one step further: with the help of artificial intelligence, Dorfner is the first company to develop optimized standard mortars to significantly reduce CO2 emissions.

With the increasing need to incorporate climate and environmental aspects into construction planning, the use of metakaolin will become more important. In view of the potential elimination of fly ash from coal combustion in Europe, the need for alternatives such as metakaolin will continue to grow. Dorfner is in an advantageous position to benefit from these developments due to its excellent supply capability, especially due to its proximity to our European customers, the availability of raw materials from our deposits and the short transportation routes, which also cause little CO2 emissions.

Continuously monitoring the market and recognizing new business areas are crucial to ensuring long-term success in the building materials industry. With innovative solutions such as Metakaolin, Dorfner will not only contribute to reducing CO2 emissions, but also help shape the future of the construction industry in a sustainable way.  

Metakaolin – a key to climate-friendly construction With DORKACOM® 50 and DORKAPUR® 100, Dorfner offers two metakaolin products that are ecologically and technically impressive. By integrating AI and digital formulation development, Dorfner is setting standards in sustainable building material innovation. Metakaolin thus becomes a central building block for CO₂-reduced construction – efficient.