NZ build

[JSeward]

Thanks David, but I am a little confused, is it ok to cast an unfired floor by myself or not ? It is sounding like I was sold a line by the guys who sold me the cement

Cheers

[david s]

I'm not clear on what they sold you. If it is just the calcium aluminate cement then it's probably Ciment Fondu, there are other brands. You may also have been sold a premixed castable (just add water) Contact your supplier to clarify exactly what it is that they sold you.

[JSeward]

Sorry I probably wasn't too clear. I have calcium alumina cement, they told me it's the cement they use in their fire bricks and refractory tiles. I was told a 4:1 ratio of sand -cement concrete would work in place of fire bricks. Cracking aside, I am a little concerned the surface will degrade faster than firebrick

[david s]

I use a proprietary castable refractory, but if I were making my own brew I'd add a little powdered clay in the mix to make it more workable and also add some fine polypropylene fibres which will disperse when mixed well and burn out at 160C leaving a network of fine pipes to assist water removal and reduce any steam spalling tendency. Ask your supplier if they have them or get them from specialist concrete supplies.

[JSeward]

Cheers for all the tips, I think I'll spend the cash on fire brick/ tiles, or maybe finish the cooking surface with tiles, 25mm ones are easy to get, with the refractory concrete beneath.

This wouldn't cause a heat break would it, i.e. due to two differing materials ?

[david s]

Provided the surface is smooth and flat you'll get good contact and heat flow by conduction.

[JSeward]

Thanks again, much appreciated