P2
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Posts: 13 
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Post by P2 on Jun 9, 2017 13:02:33 GMT -8
There are a lot of formulas for casting refractory parts to be found. I wish to ceep things simple and the most recepies contains 15-30% CA and grog. The grog may be divided in different particle size and/or material, but most commonly crushed fire brick and sand (sand, i dont know...cheaper?!). In a significant number of formulas, fire clay is also added in a total amout of roughly 20-30 %.
To what use is the fire clay if the mix harden chemically anyway? Dispersion? Incresed density/less remaiming pores after hardening, control mix viscosity or what?
Thanks
P2
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Post by Vortex on Jun 10, 2017 0:55:16 GMT -8
Not sure if this is correct, but the way I've understood it is the CA cement forms a chemical bond that is stable up to 1200*C, the clay when fired to a high temperature forms a mechanical bond effective at higher temperatures.
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P2
New Member
Posts: 13
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Post by P2 on Jun 10, 2017 20:42:04 GMT -8
Yes, that could be a reson.
Is it possible to reduce the amout of water added if the clay is ignored? If so, is it desireable or just a consequence?
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Post by Vortex on Jun 11, 2017 0:10:35 GMT -8
Not sure. The commercial CA+grog castable that I've used recommends 3-5 litres of water to 25Kg. I would experiment by adding it a little at a time until you get the correct consistency.
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P2
New Member
Posts: 13
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Post by P2 on Jun 12, 2017 11:52:26 GMT -8
Thanks, maybe the clay only is a heritage from the use of clay in mortar and people though it would be suitable in castings as well...
I'll try later. I have a lot of reading-up and planering to do.
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