Technical - Castable Firebrick Floor

The castable firebrick matterial we use in JUCAs is generally rated for opeartion from 220°F to 2600°F temperature. The very hottest part of the flame of a wood fire is about 2300°F, so this material could withstand absolutely any fire circumstance that could possibly happen.

Generally, that hottest part of the fireis several inches above the floor, and its heat rises to go up. This situation makes it such that the castable firebrick NORMALLY never gets over about 900°F, well within its range, assuring very long life.

The castable firebrick material we use, was also selected for its abrasion resistance, to make sure that it will easily withstand the rubbing of an ash shovel or other tools on it.

The specifications of one brand of this material that we use is: Cured to 220°F, the cold modulus of rupture is 1050 psi, and cold crushing strength is 9100 psi. The material stays within 0.1% of its cold dimensions, thereby not causing self made stress cracks.

Cured to 1500°F, the cold modulus of rupture is 650 psi, and the cold crushing strength is 5500 psi. At this temperature, the overall dimensions get smaller by 0.1%. In a JUCA, this means that if the unit was used ferociously hard, such that the entire castable floor got to 1500°F, there would only be a 1/64 inch space appear around the edges of the firebox. This would NEVER allow ashes to ever get down to the metal below to do any deterioration.

The density of this material, when in the JUCA, is 131 pounds per cubic foot. The amount of water needed for casting is 11.4%.

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Its thermal conductivity is 4.9 Btu/hr/sqft/°F/ 500°F operating temperature.

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