Refractory Mortar Help Needed - Please

[mpholland]

I am ready to start the dome and cannot get the ingredients I need to make the refractory mortar. No hydrated masonry lime (only granular garden type) is available locally and no 1:1 portland:lime mix can be found.

What I have found is Cement-Lime Type S mix from Holcim which I've determined is 2:1 portland:lime. Two questions. First, can I use this to make my mortar? Second, if I can (hope so!) should I mix it to yield 2:1:1 portland:lime:fireclay (plus the right volume of sand) or 2:1:2 portland:lime:fireclay (plus the right volume of sand)?

I know the mixture is suppose to be 1:1:1 but would it be better to have more portland (the 2:1:1 mix) or a little less lime (the 2:1:2 mix?)

Hopefully one of these approaches will work or I'm stuck.

Thanks.

[Les]

Re: Refractory Mortar Help Needed - Please

MP,

I see no reason why it wouldn't work. I would go the route of using less lime.

Les...

[david s]

Re: Refractory Mortar Help Needed - Please

Try the second brew (less lime) Portland cement doesn't like high heat so doubling its quantity might be asking for trouble. The extra fireclay could give you shrinkage problems. Try it and see.