Making fire clay bricks

[Kevin horlyck]

I’m going to make my own fire clay bricks. I found a bunch of recipes online for bricks the best one I think is 1 part fire clay 1 part Portland cement three parts sharp sand and one part perlite. I’m hoping to find some people that have made their own bricks and get some good or bad feedback! This is my first attempt to build a brick pizza oven so please let me know what you think of this recipe thanks lost in Santa Cruz haha Kevin

[david s]

Good luck, but be aware that Portland cement is good for up to 300C then begins to break down, which is why hydrated lime is usually an ingredient because it is good for 500C (above our service temps), before it starts to fail. Also the addition of perlite to the mix reduces its strength and makes it more insulating and therefore more difficult to heat up because the conductivity is reduced by adding an insulator. The resulting reduction in thermal mass also reduces the capacity of the material to store heat. At temperatures below 527C (WFO service temperatures) the clay content will not be made permanent, so should be considered a very fine aggregate, so it therefore should not be considered as a cementious component.
It would also be advisable to add some burnout fibres in the mix 1% by volume, to reduce the risk of steam spalling.
Let us know how your experiments turn out so we can all learn from your experience.