Sometimes geopolymers are said to have N-A-S-H (sodium aluminium silicate hydrate in the cement chemist notation) gel as the binding phase. I was wondering what is the difference of N-A-S-H and zeolites if any? Zeolites are also frequently present geopolymers and they are also aluminium silicates with hydrated sodiums.
1) A zeolite is an aluminosilicate porous solid (natural or synthetic) that has a periodic porous structure, which is characteristic of each zeolite structure type; while N-A-S-H does not (usually) show a regular layout of pore systems.
2) Many zeolites do contain other cations, instead of Na(+). For instance K(+), Mg(2+) and so on; or even a mixture of them. In other words, zeolites are not necessarily sodium aluminosilicates.
Hope that helps.
Best wishes,
Carlos
I put more words, in addition to Carlos response. Zeolites are highly crystalline (mostly), whereas other aluminosilicate counterparts are amorphous in nature. Zeolites possess high Si to Al ratio compared to geopolymers (lower than 2-3). Zeolites are micro and mesoporous with higher SSA whereas pure geopolymers are low in SSA (mesoporous). Zeolites are more organised framework and cage and pore confinement. I share more ideas how to improve key properties of geopolymers which can be utilized similar way like zeolites.
Geopolymer is an amorphous N-A-S-H and Zeolite is a Crystaline N-A-S-H
The main difference between them is that zeolite is crystalline while geopolymer is amorphous. The growth of crystalline phases is facilitated by the high water content, high curing temperature, aging and also extended curing period. Zeolites are highly porous and have poor mechanical properties.
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