my mix became extremely lumpy and had no workability (flow at all )all it had was lumps what could possibly be the problem ?
take note that water was added once the lumps were formed to try and solve the problem however there was no difference
Yusuf Dhooma there could be plenty of reasons from the wrong Si/Al and Si/Na ratio to inapplicability of this specific fly ash for geopolymer synthesis.
You should check the general steps of technology: amount of NaOH and sodium silicate, its ratio, amount of their mixture for your fly ash.
Dear Yusuf,
simply you are not doing any geopolymer material but only an over saturated and too much alkaline mud or something like that.
You need to know the fundamentals of geopolymerization that isn’t alkaline activation so doesn’t need so high amount of NaOH or your fly ash (what type? Only class F can be used for correct geopolymer reaction ) is useless.
You must study better what is a precursor and what is a reagent alkaline or acid, depending on the target of your work.
Precursor needs to be investigated about its mineralogy , chemistry and particles size distribution to know how to use.
Liquid reagent must be at the right molar ratio and precisely dosed to obtain a geopolymer binder.
After that you need to know how to mix both parts and when add the aggregates.
But even fly ash F isn’t the best precursor to use at room temperature and finally after hardening mechanical properties remain quite weak. Other thing if you cure at higher temperature but I suggest to check at the Geopolymer Institute site : www.geopolymer.org
Read all free technical papers and watch the videos where Prof. Davidovits explains the fundamentals of this technology.
Have a nice work.
Best regards
Alex ReggianI
Dear Yusuf,
I think you can use 10 - 12 M sodium hydroxide solution but as described above, you should learn more about the preparation of geopolymers before the experiments.
Best regards,
Attila Baranyi
2:1 NaSiO/NaOH and 10 mol are suitable. In addition, the water/binder ratio is 0.35
Hi,
Alex Reggiani's answer is the good one. You must learn the polymer chemistry, it is not a hydrate or an alcali activated dirt. Forget everything you know about OPC, it does not apply to geopolymers.
There is the book on geopolymer chemistry (5th edition + tutorials) too: https://www.geopolymer.org/shop/product/geopolymer-for-newcomers/
There is a 2.5 hours video on Geopolymer Processing. It reveals everything. This is the know-how you are looking for. It is a pragmatic approach for technicians and engineers. It details how to select raw materials, how to calculate a formula, and a description of the process method for optimal results. Chapter 21 of the book is also covering these issues.
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