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Non-Refractory Castable

An alternative to true refractory mortar is to make a non-refractory high-temperature mortar using a 3:1:1:1 ratio mixture (by volume, not weight) of fine mesh sand, Portland cement, fireclay and hydrated lime. While Portland cement starts to break down at temperatures as low as 400ºC (732ºF), temperatures that your pizza oven dome will experience every time it is fired, the fireclay and hydrated lime serve as backup binders, holding the material together over time as the Portland cement starts to degrade.

You can use this fireclay mortar, in a pinch, to cast a pizza oven dome. It will definitely crack and not last forever, but it’s easy to work with, and you can use it with a sand or cardboard pizza oven mold to build a very low-cost oven.