if you didn't use any air entrainments or foaming agent as the situation in cellular or foamed concrete, it could be normal air bubble generated accidentally when mixing or it is air entrapped in the original ingredients, so try to use vibrator and see what would happen.  

Those bubbles could be just air trapped in your mixture during mixing. Have you tried vibrating the mixture (similarly as making regular concrete) for couple of minutes before allowing it to consolidate? That should remove air bubbles.

Do one thing: Run GC on your gas or gaseous sample and see what is really coming off. Let me know what you do you observe. 

Ther are specifically two types of bubbles in a concrete mix: The micro bubbles that normally are generated by and admixture that added this kind of bubbles in the concrete, this microbubbles are specially important en concrete submitted to icing and deicing processes and the macrobubbles, well known as trapped air, that a considerable part of them are eliminated during the vibration of the concrete, but certain quantity is impossible to eliminate between 1 to 2,5% of the volumen of the concrete.

if you didn't use any air entrainments or foaming agent as the situation in cellular or foamed concrete, it could be normal air bubble generated accidentally when mixing or it is air entrapped in the original ingredients, so try to use vibrator and see what would happen.  

Yes, I used vibrator and the bubbles comes to the top but a new bubbles then is created. And I think this is not a air trapped air in mixing, because even when i mix manually still bubbles comes out. I think that is nitrogen trapped in nanoporosity in zeolite and when I dry the zeolite water inside of this nanochanels evaporate and nitrogen cover the vacant space. This chanels are around 0,7 nm in diameter.

In case you don't have access to expensive equipment, you could try narrowing down the possibilities using a method like the glowing splint test.

Sinan T. Erdogan, thank you for you answer. How can I perform the glowing splint test, Isn't it for oxygen recognition.

I am also curious how to collect the gas, I think it is not so much.

For a chemical perspective of the geopolymerization of inorganic polysialates you may want to check section 8 at: J. Šesták, C.A. Queiroz, B. Foller, Ch. 3 in: D. Křemenáková, R. Mishra, J. Militký, J. Šesták (Eds.), "Selected topics of textile and material science", Publishing House of West Bohemian University, Pilsen, 2011, pp. 53-75.

Chapter Some aspects of vitrification, amorphisation and idiosyncrat...