Masonry Magazine December 2012 Page. 20
Refractory Mortar
Refractory mortar for masonry fireplace and chimney construction
By Jim Buckley and Bob Rucker
In recent years, we have seen vast changes regarding masons' preferred choices of mortar for firebrick (fireplace) and clay flue liner (chimney) installations. Jobsite prepared mortars that may have included fireclay and Portland cement are now out of favor. Factory prepared refractory mortar is now the most widely accepted standard.
Refractory mortars have become easier to use, safer, are more readily available, and meet all of the local and national building codes. Masons who resisted them at first, now accept them as a better, safer masonry product, offering their customers a higher quality installation. No more guesswork regarding homespun mortar formulations, liability issues, or concerns regarding code compliance. And, without getting into all of the detail about the fireclay mixes breaking down and losing strength as they pass through the temperature range of 600 to 800 degrees, they simply don't take the heat like refractory mortars do, nor do they have the strength or acid resistance.