Can you elaborate self condensation? If you are referring to crystallization, solution may have become super saturated. Kindly refer the following link for generic information: http://www.reciprocalnet.org/edumodules/crystallization/index.html

Dear Vivek,

I agree with Sanchit Gupta, your solution is over saturated then precipitates. But the most common issue is about solubility of these ingredients that changes depending on temperature and pressure (higher temperature means more soluble and the result is less viscous liquid) but also on quality of sources. Sodium based are much more viscous than potassium based. At room temperature it’s difficult to obtain something stable for long time, it’s suggested for R&D trials or becomes mandatory , when you want to sell industrially, to use the correct equipment (autoclave). By the way your solution with that ratio is too much alkaline, so corrosive, take care about handling and use protective clothes and gloves.

Best,

Alex Reggiani

Hello

I agree with Sanchit Gupta

Dear Vivek,

Stability of activation solutions closely depends on the Na2O, SiO2 and H2O contents. It is strongly affected by temperature (low temperature accelerates their crystallization). Don't worry if your solution gets slightly self-condensed, most silicate solutions that are of high importance in geopolymers are partially crystalline.

Best regards,

Abdelilah ABOULAYT

I also expereince this problem, I used 12M NaOH solution and Na silicate and put it in a plastic sample holder. The solution turned to solid wax after i mix it for 5min. First I thought it was the container so changed it to a glass container. Still the same has happened. Abdelilah Aboulayt said temprature may have an effect. the solution I made was placed in a room at 20oc. I am doing some tests and will let you know if there are some changes.