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AMORPHOUS CALCIUM ALUMINATE

Amorphous Calcium Aluminate Cement (ACA) is on of the latest developments in cement chemistry. There is not a published on this subject so therefor this blog.

Main phase is C12A7 (mayenite) a most reactive phase in cement hydration.

Amorphous calcium aluminate can be used as an additive in cementitious compositions as an accelerating agent to Portlandcement.Other features are rapid drying and compensation of shrinkage through positive expansion.

Production Raw materials are completely molted in a furnace to form a liquid calcium aluminate clinker.

After completion of calcination the clinker is cooled rapidly to a temperature lower than its crystallization temperature to secure an amorphous calcium aluminate.

To further improve its solubility the glass like clinker is ground to a high surface area.

Cement mortar

Amorphous calcium aluminate dissolves most rapidly releasing aluminate ions into the pore structure giving, in combination with calcium sulphate, extreme fast formation of calcium            tri-sulpho-aluminate;

 3CaO,Al2O3.3CaSO4.32H2O

It is found that formation of crystalline C4A3Ŝ is practically instant and all sulphate consumed. 

Caltra offers two types differentiated by its chemical composition ; 

CALUMEX SC-A - at 10~20% replacement of Portlandcement gives instant set, high early strength, rapid drying at predominantly used in mortars like Postfix,Waterplug,Shotcrete etc.

CALUMEX XT-20 - at 10~20% replacement of Portlandcement gives a ~20 min. set, progressive increase of strength, rapid drying at predominantly used in mortars like Tile Adhesives, SLU, 3D printing etc.

Environment

Because of its high efficiency in production of cement mortars the use of amorphous calcium aluminate allows formulators to reduce the binder amount considerably in their formulations, 

up to 40 %!.,not only giving cost savings but also contributes to a lower CO2 emission.