How to Install Firebrick Mortar

Firebrick mortar, while being a subtype of standard construction mortar, is actually quite similar to standard mortar in how it is mixed and applied. Rather than using Portland cement for the mortar's cementing bond, firebrick mortar uses a compound called calcium aluminate in the mixture. Where Portland cement would eventually disintegrate due to the heat, calcium aluminate is heat resistant and will remain solid for decades.

Mixing container
Water
Trowel
Masonry pointer

Instructions

- 1
  Dump the bag of refractory mortar into the mixing container, then add enough water -- while mixing with the trowel -- to bring it to a peanut butter-like consistency.
- 2
  Apply 3/16 of an inch of mortar onto the brick or stone that you are laying. Firebrick mortar should be no thicker than 1/4 of an inch after it has set. Applying 3/16 of an inch to the brick allows for 1/16 of an inch of compression, to allow the brick or stone to settle into place.
- 3
  Set the brick or stone into place, pressing it slightly to obtain the necessary 1/4 of an inch or less of thickness.
- 4
  Smooth the mortar between the bricks using the masonry pointer. This will help remove any air bubbles and will smooth the joints between the bricks, to provide a uniform appearance.

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