Pozzolans

Metakaolins, like coal fly ash, are type II latent hydraulic (pozzolan) cement additives that can be used to replace part of the cement due to their hidden hydraulic properties. The raw material of metakaolin is kaolin, which belongs to the group of layered silicates and aluminosilicates. It is produced by heat treatment (calcination) between 500 and 800°C, during which the interlayer hydroxyl groups are removed from the system. Metakaolin can react with portlandite (calcium hydroxide) and forms calcium silicate hydrate (CSH) and calcium aluminum silicate hydrate (CASH), water-insoluble phases found in concrete. The average particle size (d50) characteristic of metakaolins is 3-5 µm, i.e. larger than microsilica, but an order of magnitude smaller than Portland cement. Its specific surface area (Blaine) is between 23,000 and 26,000 cm2/g.

Microsit type II latent hydraulic (pozzolanic) cement additives are purified and graded coal fly ash. Our offer includes the following types: Microsit 10 (d95 grain size 10 µm), Microsit 20 (d95 20 µm), Microsit 90 S (d95 90 µm). Microsit coal fly ash particles, due to their almost perfect spherical shape, improve the self-compacting process of concrete and reduce the amount of superplasticizer required. The high k-value of all Microsit type coal fly ash allows its use in CEM II and CEM III type cements. Due to their concrete pore volume reduction and pore distribution improvement effects, Microsit coal fly ash increases the resistance of concrete to dissolution and swelling corrosion caused by sulfates. The resulting denser matrix also significantly increases the surface abrasion resistance of concretes and mortars. Since Microsit coal fly ash "F" grade pozzolans contain more amorphous silica compared to "C" type fly ash.