Metakaolin is available in many different varieties and qualities.
The purity will define the binding capacity for free lime. Some of
them also provide special reactivity. 

 

Metakaolin is a valuable admixture for concrete and/or cement applications. Usually 8% - 20% (by weight) of portland cement 
replaced by metakaolin.  Such a concrete exhibits favorable
engineering properties.  The  pozzolanic reaction  starts  soon
and continues between 7 to 28 days.