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What is Metakaolin?

Definition of Metakaolin

Metakaolin is defined as an anhydrous calcined structure of the clay mineral kaolinite, used for centuries in the production of porcelain and more recently as a pozzolanic additive in concrete to improve resistance to chemical attack and enhance longevity and structural integrity. 

Metakaolin is an off-white manufactured pozzolanic mineral admixture that considerably increases the many functioning features of cement-based products. The particle size of metakaolin is significantly smaller than that of standard cement grains, providing a greater surface area for supplemental reactions to occur. R-E-D Industrial offers Dynapoz Metakaolin which is a refined kaolin clay that is calcined at precise temperatures ranging between 600 and 800 ℃ over an extended 12-hour time period. This heat-treatment process creates what is known as an amorphous alumina silicate. When used as a supplementary cementitious material (SCM) to cement and water, the aluminum silicate will react with the available calcium hydroxide present in the portlandite to produce additional binding materials such as calcium silicate hydrate in cement. 


Chemical Composition of Dynapoz Metakaolin

For a complete breakdown of the chemical analysis of the Dynapoz Metakaoling offered by R-E-D Industrial Products, please refer to the detailed product information sheet and safety sheet. The exact mineralogy of this product is 82.5% amorphous with the next largest percentage being Quartz at 12.8%. Below is a list of the specific chemistry of our metakaolin product and the exact percent of the makeup they compose. 

Compound

Percentage

SiO2

57.2%

Al2O3

36.7%

Fe2O3

1.78%

Cao

0.48%

MgO

0.36%

Na2O

0.08%

K2O

1.08%

TiO2

2.01%

P2O5

0.12%

SrO

0.04%

 

Specifications of Metakaolin

R-E-D Industrial Products metakaolin conforms to ASTM C618 Specifications for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Concrete, meets AASHTO M295-11 standards, and is classified as a Class N material. A brief description of each specification, guiding doctrine, or classification is listed below. 


  • ASTM C618: This specification covers a wide range of pozzolanic materials used in concrete including Coal Fly Ash and other raw or calcined natural pozzolans such as metakaolin. Any material falling under this scope must meet prescribed chemical composition and physical requirements. Additionally, the material is thoroughly tested for particle fineness, necessary water requirements, strength activity index, and other qualities that dictate final performance. 

  • AASHTO M295-11: The American Association of State Highway and Transportation Officials (AASHTO) M295-11 standards also cover Coal Fly Ash and other raw or calcined natural pozzolans used in concrete applications. M295-11 also provides a rigid list of chemical composition standards and testing requirements for SCMs such as metakaolin to ensure adequate performance in concrete applications. 

  • Class N Material: Metakaolin is a Class N material which designates it as a raw or calcined natural pozzoloan. Other Class N materials are diatomaceous earth, shales, and some clays or shales provided they require calcification to attain satisfactory properties. 


Environmental Benefits of Metakaolin on Concrete

The manufacturing process of Portland cement often creates a large amount of carbon dioxide emissions, a known greenhouse gas. By replacing just a portion of the Portland cement in the overall cement mixture with Metakaolin, companies are actively reducing the amount of CO2 emissions while adding several performance-enhancing benefits. When scaled up to the size and scope of infrastructure projects, the addition of metakaolin to cement or concrete significantly reduces the carbon footprint. Furthermore, the improved water and thermal resistance of metakaolin-enhanced concrete leads to reduced erosion and potential catastrophic defects that necessitate repairs or total replacement. 


Making concrete with metakaolin is a more proficient process as it diminishes the consumption of Portland cement as well as strengthens the desired properties of the concrete. Thanks to the added strength provided by metakaolin to concrete projects, fewer additional support structures may be required to achieve the same results. Additionally, considering the impact metakaolin has on the composition of concrete it becomes far less susceptible to chemical attack that leads to cracking. Ultimately creating a more efficient infrastructure that necessitates far less maintenance and leaching of material into the surrounding environment. Lastly, metakaolin differs from other SCMs as it is not an industrial by-product and is instead manufactured by heating the naturally occurring clay mineral kaolin. 


Applications of Metakaolin

Metakaolin is ideally suited for a wide variety of cementing applications due to it being a reactive amorphous pozzolanic material that contains latent hydraulic properties and an overall finer particle size than cement. The finer particle size is exceptionally useful in creating additional surface area for chemical reaction sites within the concrete mixture. An increased number of beneficial chemical changes creates concrete with improved structural integrity and greater resistance to the harsh environmental conditions infrastructure projects typically encounter. 

These properties provide good particle packing capabilities. Because these properties are particularly desired in the oil and gas industry, these companies will utilize metakaolin in their cementing mixture to increase the hardening strength of the cement to withstand compressive forces and reduce the loss of both liquids and gases to permeability. The use of metakaolin is not restricted to infrastructure projects and oil industry applications. Thanks to the impressive enhancements provided by metakaolin as a supplementary cementitious material it can be extremely beneficial to a variety of other unique applications.


Common Uses of Metakaolin

  • infrastructure projects - marinas, piers, and bridges

  • oil well cementing

  • precast & repetitive concrete products - cast stone, paving blocks, and bricks

  • decorative concrete floors

  • pavements - residential & commercial

  • mortar, stucco, and pool plaster

  • grout, decorative interior fixtures, and sculpting

  • residential, industrial, and commercial construction applications


Choose R-E-D as Your Metakaolin Supplier

With over 40 years of experience providing clients with the highest-quality SCMs, we are confident that our metakaolin will meet your budgetary requirements, performance specifications, and deadlines. Customers can order metakaolin from R-E-D in 40-pound bags with 50 bags to a pallet, in bulk 2,000-pound palletized bags, or bulk delivery via truck. You can contact us at any time to learn more about metakaolin or any of our other products and receive a quote. 




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