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Calcium Hydroxide question?
New process at work isnt going to well and I wondering if there was a chemical answer to the question
Basically Im mixing calcium hydroxide with water and making a paste. This paste goes hard about 50mins or so after it as been mixed.
Now the process calls for using some old waste paste, milling it down drying it out and replacing 5% of the fresh stuff with 5% of this old stuff. Now some reason the addition of this 5% makes the paste go hard in about 30mins instead of the usual 50 mins.
Anyone have any idea why? Any help would be appreciated
P.S.
We also add a hardening agent but its concentration doesnt change between the different mixes
1 Answer
- Facts MatterLv 71 decade agoFavorite Answer
The hardening of pastes is a very complicated process. I guess that may be the old hard paste mixed in with the new acts in something like the same kind of way as seed crystals do in a supersaturated solution, helping the individual calcium hydroxide particles line up.
There may be other possibilities involving the role of carbon dioxide.
So I don't know the answer to your question, beyond telling you that it is a very interesting one.
Source(s): Research on inorganic precipitates.
