Dear Raheem,

I suggest to participate at the next GP Camp in Saint Quentin en Picardie from 10 to 12th of July 23, what you are asking is one of the main topics treated every year.

Of course Metakaolin only if correctly calcined from 750°C (the best reactivity) to 1150°C (still usable but less reactive) is the most typical precursor powder useful for many applications.

If calcined at higher temperature becomes a calcined kaolin till a chamotte losing the most of its reactivity becoming not suitable to be used as precursor, but only as refractory partially reactive filler.

Due to the fineness and high BET (superficial area) of particles Metakaolin needs to be known. It has for sure an high reagent demand (alkaline silicate or proper acidic solution) so could be used even for concrete but isn’t a cheap system.

Concrete is very low tech material, usually Metakaolin should be used for more hi-tech materials ceramic like, at least this is my experience.

If you have a cheap grade of Metakaolin locally you have just to redesign the dosages between Geopolymer binder (precursor and reagent) and a balanced curve of aggregates, paying attention to the fine fillers distribution to avoid shrinkage with the hardening.

Geopolymerization isn’t hydraulic process like OPC and Alkali Activated Materials (AAM) so you must forget all the rules used to design a those kind of concretes. Specially water / binder ratio is non sense parameter at all, because nothing will react with water.

Inside the book of prof. Davidovits you can find all suggestions to work at best, selecting several different mineral systems, even for concrete application.

You can find at the shop area of the Geopolymer Institute site : www.geopolymer.org

All the best

Dr. Alex Reggiani