posted 3 weeks ago
I have researched it a bit. Usually it's recommended to use the same amount wood ash as water glass by volume. So assuming we have the aforementioned 100 kg of ash (from one cord used for yearly heating) it would be volume of 60 l (assuming specific gravity of 1.6), so we would need 60 l of water glass (40%), which is around 16 gallons. I saw 1 gallon on amazon for $20, so it would need at least $320 of water glass to make equivalent of 4 bags of cement (worth $80).
If we purchased water glass cheaper (amazon includes shipping), let's say at $10 per gallon, it would still amount to $160. So only if water glass could be sourced very cheaply ($4 per Gal), it would be cheaper than cement. It's possible that if purchased in barrels (or tanker trucks) it would be quite cheap, after all it's a simple material made of most popular elements.
Of course wood ashes come in all flavors and they could react differently resulting in different final product.
It's an interesting topic. I need to experiment.