Dear ,

particles size distribution is key point of every technology. Fly ash I hope you are referring only to class F (Geopolymerization cannot occur using class C, for lack of amorphous alumina from minerals inside), is pure waste so the most important thing is to know its mineralogy, chemistry and of course particles size without forgetting amorphous content and calcination temperature of the fly ash F.

After that using this inconstant precursor only at room temperature you will have weak mechanical strength (even micronizing more…but keep attention on the analysis and use gas mask because normally there is inside also heavy metals like lead, it’s not a by product at least partially processed). Remember that GP aren’t Alkali Activated Materials so mix design is completely different.

Of course if you use heat curing like precast technology mechanical strength will be better. But basic Concrete in job site cannot be heated so if your project wants to become interesting shift you attention from particles size to the using the correct raw materials (fly ash F is not enough alone even If more fine) to obtain stable material like OPC based (even and in particular after 1 month of water curing) at room temperature.

For more informations I suggest to have a look at www.geopolymer.org and to participate at next GP Camp in France

Best regards

Alex Reggiani