Masonry Magazine September 2002 Page. 28
Mixing Mortar
MIXING MORTAR
FOR
PROPERTIES
The Prescription Mortar Method
BY TOM INGLESBY
Does any one unit fit all situations? Not likely. Since the units are highly variable, why couldn't the mortar be too? Matching unit and mortar is the answer and that's 'prescription mortar.'
It's a sticky topic, we know, but mortar is one of the most basic elements of masonry construction. Yes, you can build without it these days as dry-stack blocks are becoming more popular but when nature becomes pushy, you want that tall wall to withstand gale force winds and even earthquakes. That usually means mortar joints.
What is mortar? "Any of various bonding materials used in masonry, especially a plastic mixture of cement or lime, sand, and water that hardens in place and is used to bind together bricks or stones." At least, that's what the American Heritage Dictionary says.
The people who make the bricks, as represented by the Brick Institute of America (BIA), go into more depth, as you would expect. "Mortar is the bonding agent that integrates brick into a masonry wall. Mortar must be strong, durable, and capable of keeping the wall intact; it must help to create a water resistant barrier; and it must accommodate dimensional variations and physical properties of the brick when laid. These requirements are influenced by the composition, proportions and properties of the mortar."