Metakaolin-enhanced concrete is a concrete mixture that uses a calcined aluminosilicate kaolinite clay (metakaolin). Metakaolin’s highly porous structure and mineralogy give a larger surface area and better opportunities for a pozzolanic reaction and improve structural integrity and durability. It is widely used in infrastructure projects, oil industry applications, and marine environments.
What is Metakaolin?
Metakaolin has a chemistry high in amorphous alumina and silicon dioxide content; these compounds are essential in a pozzolanic reaction within concrete. Metakaolin reacts with the calcium hydroxide in the cement during cement hydration, forming calcium silicate hydrate (C-S-H) or calcium alumina silicate hydrate (C-A-S-H). C-S-H and C-A-S-H are highly desirable binders in concrete that improve strength and durability. As other long-used supplementary cementitious materials (SCMs) like fly ash and slag have become increasingly difficult to source, many companies are exploring alternative additives from calcined clay, such as metakaolin.
How is Metakaolin Produced?
Kaolin clay forms through the chemical weathering of highly concentrated aluminosilicate minerals like feldspar. These Kaolin clay deposits are typically surface mined and calcined to between 400 and 800 ℃. During the heating process, the kaolin undergoes a dehydroxylation reaction, in which it loses water molecules and converts the kaolin to an amorphous, pozzolanic aluminosilicate called metakaolin. Finally, these newly formed chunks of metakaolin must be ground to a powder.
Why Use Metakaolin Concrete?
Considering the current industry demands, there are many reasons to use metakaolin in concrete. Metakaolin is used primarily for its pozzolanic reactivity, and the additional calcium silicate hydrates and calcium aluminosilicate hydrates it produces. These minerals provide cementitious properties that enhance the durability and strength of concrete. When we look at metakaolin's uses, there are three primary goals:
Performance: Metakaolin in concrete improves the structural integrity and compressive strength of the cured concrete and offers tremendous resistance to erosion, thermal fluctuations, environmental conditions, and chemical attacks from things like road salt. Metakaolin is one of the best supplementary cementitious materials for reducing concrete permeability, improving durability, and increasing compressive strengths, thus leading to much higher-performing concrete.
Cost: Reducing cost is a critical goal of any large-scale project, and adding metakaolin to concrete can have both upfront cost advantages and long-term benefits. The improved lifespan and durability reduce lifetime costs associated with the continual maintenance, repairs, or replacement of lower-quality cement. Metakaolin can often be a good alternative to more expensive performance-enhancing SCMs.
Sustainability: Using metakaolin in concrete has several sustainability benefits. As a relatively green product, substituting a percentage of concrete mixtures with metakaolin helps to reduce the CO2 emissions produced during manufacturing. The production of metakaolin uses half the energy of cement clinker, and as a cement replacement, it can lead to concrete with significant carbon output reductions.
What Are The Applications of Metakaolin Concrete?
Metakaolin in concrete can be used in various applications that require enhanced structural strength, durability, and lifespan. The predominant use of this product lies in large-scale infrastructure projects that experience significant and continual traffic, including industrial equipment and heavy machinery. It can also be utilized in specialty cases such as oil well cementing and even interior decorative concrete fixtures or sculpting. Additional applications of this product include but are not limited to:
Marine environment projects such as dams, bridges, piers, and other water retaining or off-shore structures
Structural and non-structural components of high-rise buildings, parking garages, interstates, and power plants
Industrial flooring for warehouses, manufacturing facilities, fabrication companies, and trucking depots
Concrete adhesives like cement-based grout and mortar
Precast or repetitive concrete products such as stone, blocks, bricks, and paving stones are used in both residential and commercial construction applications
R-E-D Metakaolin Concrete
R-E-D Industrial is one of the North American metakaolin suppliers that both produces and provides metakaolin for sale directly to consumers in the concrete and plastics industries. We stand behind our Dyanpoz Metakaolin product as an excellent material to meet the current demands of our rapidly growing & changing concrete industry. Our website offers additional resources and information about metakaolin and other supplementary cementitious materials we supply, like silica fume, ground glass pozzolan, and nano/colloidal silicas. To speak with a member of our team or receive a quote for metakaolin, please send us a message with more information about your project requirements.
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