Anyone ever tried adding citric acid to refactory cement?

[di11on]

Apparently it gives you more time to work with the mix... interesting article:

https://www.elkem.com/Global/ESM/support/technical-papers/refractories/36-Flow%20and%20Flow%20Decay%20of%20Refractory%20Castables.pdf

[wotavidone]

Re: Anyone ever tried adding citric acid to refactory cement?

Interesting. If the refractory manufacturers reckon it works - it works.
The other interesting bit is the difference in flow times depending on temperatures.
It appears the easiest and cheapest thing to do would be to use ice water to formulate the castable, as Davids recommends.
I imagine if you had a tub of water with big blocks of ice in it to use for your mix water, and picked a nice cool day to cast your refractory, you should not have any difficulty with rapid set.

[stonecutter]

Re: Anyone ever tried adding citric acid to refactory cement?

Old timers used sugar as a retardant for mortar. I've never tried it though.

[david s]

Re: Anyone ever tried adding citric acid to refactory cement?

Yes, I've heard that citric acid can be used, but you have to be extremely accurate with additions, also I have no idea how it might affect resulting strength so haven't tried it. I prefer to use chilled water. Sugar can work for retarding portland going off, but I'm not sure if it applies to calcium aluminate cements as well. Here in Australia I'm told the cement mixer drivers always carry a couple of kilos of sugar to dump in the load if they get stuck and can't unload it. Apparently it's enough to stop the reaction completely. Otherwise once it's gone hard you need jackhammers and dynamite to get it out