Masonry Magazine August 1982 Page. 18
Corrections and Solutions
When the mechanisms of the efflorescing salts have been established and the source of salts or moisture identified (usually the latter), there comes the problem of making suitable corrections. Such solutions to efflorescence problems usually involve the prevention of entry of water into the masonry assembly and the removal of the efflorescence salts on the wall. Removal will be discussed later in this Technical Notes.
Recommendations for the correction of water penetration in the masonry walls are contained in Technical Notes 7, 7A, 7B, 7C and 7D (Ref. 3).
Silicones
A silicone application is among the solutions most often suggested for prevention of efflorescence. The application of silicone to a masonry wall may prevent recurrence of efflorescence. However, the application of silicone to a masonry wall that has the tendency to effloresce, without interrupting the mechanisms for the occurrence of that efflorescence, may lead to disintegration of the masonry.
As stated in Technical Notes 7, "Dampproofing and Waterproofing Masonry Walls": water gaining entrance into the masonry will still take soluble salts into solution. Then as the water travels toward the silicone treated surface, most of it will be stopped at the inner depth of the silicone penetration (usually 1/8 to 1/4 in. from the face). At this point the water will evaporate, passing through the silicone treated area as vapor and presenting no problem. However, the soluble salts contained will be deposited within the masonry at the point where the water evaporates. The crystalline growth, at that point, can develop tremendous pressures which may result in spalling of the brick. It is for this reason that silicone applications are not generally recommended as a treatment for efflorescence problems.
REMOVAL OF EFFLORESCENCE
As a general rule the removal of efflorescence salts from the face of masonry is a relatively easy operation as compared with some other stains. As stated, most efflorescing salts are water soluble and many will disappear of their own accord with normal weathering. This is especially true of "new-building bloom". For this reason, it is advisable to clean new buildings as long a time after their completion as is practical.
It is usually not advisable to wash efflorescence off of the brickwork except in warm, dry weather, since this entails the presence of considerable more moisture which may bring more salts to the surface. Many efflorescence salts can be removed by dry brushing.
For recommendations concerning the removal of the efflorescing salts and other stains on masonry walls, see Technical Notes 20, "Cleaning Clay Masonry". Special care should be exercised in the cleaning operation of new masonry, since improper procedures and errors can contribute to or cause efflorescence and other staining problems.
SUMMARY
As stated, the mechanisms for efflorescence require a chain of conditions, the presence of soluble salts and the presence of moisture. To prevent or stop the occurrence of efflorescence, the breaking of either link in the chain will suffice. Recommendations have been offered in this issue of Technical Notes for the proper selections of materials, wall sections and design details to reduce to a minimum the available salts and the opportunity for water penetration. A discussion of the sources of moisture and salts and the mechanisms of efflorescence are contained in Technical Notes 23, "Efflorescence Causes".
REFERENCES
1. W. E. Brownell, "The Causes and Control of Efflorescence on Brickwork", Research Report No. 15, SCPI, 1969.
2. "ASTM Standard Specifications for Structural Clay Products Units and Mortar", an Authorized Reprint, SCPI, 1968.
3. "Technical Notes on Brick and Tile Construction", SCPI
"Cold Weather Masonry Construction"
Construction and Protection Recommendations
Winter Building Techniques in Europe
Contemporary Bearing Wall Buildings
"Moisture Control in Brick and Tile Walls"
Dampproofing and Waterproofing Masonry Walls
Flashing Clay Masonry
Rain Penetration
Condensation
Condensation Analysis
"Mortars for Clay Masonry"
"Cleaning Clay Products Masonry
Efflorescence Causes"
IA
IB
IC
7
7A
7B
7C
7D
8
20
23
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