Metacaolín

Metacaolín is a processed form of kaolin clay, a naturally occurring mineral. It is produced by heating kaolin to specific temperatures, typically between 600 and 900 degrees Celsius. This calcination process alters the structure of the kaolin, removing chemically bound water and transforming its crystalline structure into an amorphous, more reactive form. The resulting material, metacaolín, possesses pozzolanic properties.

Pozzolans are siliceous or silico-aluminous materials that, in the presence of moisture, will react chemically with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties. This reaction is particularly relevant in the construction industry. When metacaolín is added to cementitious mixtures, such as concrete or mortar, it reacts with the calcium hydroxide produced during cement hydration. This reaction forms additional calcium silicate hydrate (CSH) gel, a key binding component in concrete.

The incorporation of metacaolín into concrete can lead to several beneficial effects. It can improve the strength and durability of the hardened concrete, enhance its resistance to chemical attack, and reduce its permeability. Furthermore, metacaolín can also contribute to a reduction in the heat of hydration, which is beneficial in mass concrete applications. Its fine particle size can also improve the workability of fresh concrete. Due to its pozzolanic nature and desirable performance enhancements, metacaolín is utilized as a supplementary cementitious material in various construction applications.