Bricks and mortar.

[steve999]

Hi.
Can I use standard house bricks to construct the inner dome of my WFO, and with regards bonding them, can I use standard 4:1 soft sand - cement?

Cheers guys.
Steve.

[oblertone]

Yes you can, provided the bricks don't have holes in then. You can get away with indents, but not holes; if you can find them solid 'wire cut' bricks without indents are best of all, try a reclamation yard and remember you'll be splitting them so half bricks or damaged ones are worth haggling for.

As to the mix, bricklaying mortar relies on cement for binding, unfortunately at the temp you will reach in a wood fired oven (+500c) the cement will degrade and you'll be left with nothing but sand holding your bricks apart.

Experience by WFO builders has shown that a mix of 3-1-1-1 sand-cement-lime-clay (aka homebrew) will do the job, and remain stable at high temp.

[steve999]

Thank you Oblertone.

With regards the clay, is that the powder type? and can I buy it from Travis Perkins or Selco for instance?

Many thanks,
Steve.

[cobblerdave]

G'day
Powder clay is what's required. You can use fireclay if you wish but a lot more expensive and hard to get.
It acts as s plasticizer to the mortar. It allows a degree if 'stick' to the brick. It also allows the brick to be squished down and sideways when layed without loosing bond and requiring it to be relayed. In other words it makes the mortar a bit more friendly in the hands of of a novice like myself. It's still hard to lay bricks but easier with it in the mix.
It also contributes as a cementious part of the mix along with the Portland and lime.
Regards dave

[steve999]

Thank you Cobblerdave. Useful info there mate.