9N85 Brown Tweed, Closure Size

9N85 Brown Tweed, Closure Size

9N85 Brown Tweed, Closure Size

1S79 New Used, Standard Size

1S79 New Used, Standard Size

1S79 New Used, Standard Size

1S39 Oxford, Standard Size

1S39 Oxford, Standard Size

1S39 Oxford, Standard Size

9S60 Standford, Closure Size

9S60 Standford, Closure Size

9S60 Standford, Closure Size

9N82 Soulard Tudor, Closure Size

9N82 Soulard Tudor, Closure Size

9N82 Soulard Tudor, Closure Size

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Efflorescence Prevention and Control

Wall with efflorescenceEfflorescence is a white, crystalline deposit on the surface of concrete or clay masonry that is comprised of water-soluble salts.  Efflorescence begins when soluble salts and other compounds are dissolved in water, which becomes a salt solution.  This salt solution migrates to the surface of masonry through the masonry units or the mortar.  The water evaporates and leaves the salts on the surface of the masonry.

Since efflorescence appears on the face of the brickwork, it is often erroneously assumed to originate from the brick itself.  Fired clay brick is rarely the source of efflorescing salts.  Instead, it is much more common for efflorescence to be caused by the transfer of soluble salt from cement-based mortar, grout or concrete masonry that is in direct contact with the clay brick used in the wall.  This is known because clay brick, unlike other building materials, can be tested to determine its potential to contribute to efflorescence.  This test, found in ASTM C67, rates a clay brick as "non-effloresced" when it does not exhibit efflorescence after partial immersion in distilled water for seven days.  When similar testing is conducted on a material containing cement, the material typically fails.  Non-efflorescing brick are readily available throughout the United States.

Efflorescence that occurs on brickwork less than a year old is often attributed to "new building bloom," as shown in the photo.  In most cases, new building bloom will dissipate over time if the brickwork is allowed to dry after completion and if environmental factors such as wind and rain are given sufficient time to naturally clean the brickwork.  Efflorescence that occurs a year or more after construction is complete is generally attributed to excessive water penetration or poor drainage.

This article was reprinted from the BIA's Brick Brief, Efflorescence Prevention & Control (PDF). Please click the above link to view the full brief.  For more information on how to deal with efflorescence, please see Technical Note 23A, "Efflorescence - Causes & Prevention.