refrectory cement for final plug

[harriott]

Having been working on my WFO for a few week now and I am getting close to closing the dome.
Dome constructed from tapered fire bricks cut to shape and mortared with blackite.
As we all know this is where things get a bit harder. Instead of cutting fire bricks for the final two rows I an interested to know if anyone has used a refractory cement cast over an internal sphere to plug the top of the dome.
This seems an easier option than trying to cut and support fire bricks.
As the new trend seem to be the use of precast domes over brick I would appreciate and comment on problems this type of closure would bring
Thanks

[wotavidone]

Re: refrectory cement for final plug

Can't see why it wouldn't work, but I reckon it wouldn't look so nice.
What is blackite?

[david s]

Re: refrectory cement for final plug

Having been working on my WFO for a few week now and I am getting close to closing the dome.
Dome constructed from tapered fire bricks cut to shape and mortared with blackite.
As we all know this is where things get a bit harder. Instead of cutting fire bricks for the final two rows I an interested to know if anyone has used a refractory cement cast over an internal sphere to plug the top of the dome.
This seems an easier option than trying to cut and support fire bricks.
As the new trend seem to be the use of precast domes over brick I would appreciate and comment on problems this type of closure would bring
Thanks

Your major drawback is that you'll have to buy a whole bag of the stuff which will cost you around $50/ 25 kg bag. Some suppliers will also have a minimum bag sale e.g. you may have to buy 12 bags of the stuff. The stuff also only has a shelf life of 12 months, less if stored in a moist atmosphere, so it will probably be useless by the time you want to use it again. Castable is also designed to be fired to around 1000C otherwise it will continually cycle through the 500 -650 C range at pretty fast rate especially as it's at the top of the dome it will see temperatures this high. Having said that complete ovens operate successfully using unfired cartable. It would certainly be easier and faster.

[boerwarrior]

Re: refrectory cement for final plug

I agree it could be done... but is it really hard to cut the bricks the right size for the top 2 rows? I actually found it easier the higher I went. You don't have to cut them very accurately and you can still use refractory cement to fill in the gaps. Personally I think that is easier than building the form to create the entire plug out of refractory.

If you do go this route, however, please post pictures!

[oasiscdm]

Re: refrectory cement for final plug

Hmmm

Cut the brick. I made a plaster mould for mine and it worked a treat cutting it. Just make sure you line the hole with something to get the plug out.

Got photos on my thread.

[harriott]

Re: refrectory cement for final plug

Can't see why it wouldn't work, but I reckon it wouldn't look so nice.
What is blackite?

Thanks for the comments Guys.
Think I will persist with using the fire bricks.
Blackite is a cement/glue used for firebricks. Sold by Thermal ceramics it is great to work with but can only be used for up to 3mm thick so you need to have cut bricks or use sparingly at the face and then backfill all joints with the normal 3:1:1:1 mortar mix. Costs $60.00/ 20ltr but used correctly will build a 900mm dome.
Cheers

[Lancer]

Re: refrectory cement for final plug

Reality check, might help. I'm sure some of the adhesion is due to the mortar not being refractory but still...

Impressively skilled brick layers, Vault contructi?n. - YouTube