Protecting Your Walls, II by Barbara Jennings
Efflorescence Ruining Your Walls?, Part II
Some of the additional salts that vary in their significance are: chromium, molybdenum, vandium, chlorides, nitrates.
Vanadium, in particular, is known to produce a green efflorescence on white or buff burned clay walls. Most salts produce a white or gray deposit.
Sources of Efflorescence
There are some alkaline salts which are more water-soluble than others. They do come from many sources, however. A common problem is the movement
of ground water. It seeps into the foundation and wicks upward into the masonry, stucco or concrete causing spalling or efflorescence.
Precautions should be taken to prevent passage of sulfate-bearing water to your home wherever soil conditions indicate the presence
of water-soluble sulfates. A trained professional can give you recommendations for the prevention of water infiltration into your home's walls.
For the best overall insurance against efflorescence, seek to create the lowest absorption of moisture into your walls.
By making sure you have properly graded aggregates, a low water/cement ratio, good compaction and the proper curing techniques in place, you will go a long way to assuring that
your cement products of the maximum density and the lowest water absorption possible.
Most of the plants that produce rock, sand and gravel wash their materials so damage from these products will probably be negligible. However, sand and gravel in
their natural state may have already been exposed to salt-bearing water or soil.
A good professional will be careful to keep a low water-cement ratio formula and have good work practices to help reduce the possibility of the appearance of salts
from using water that may have been in contact with sulfate-bearing soil. Water is used for mortar, stucco and concrete.
You'll find that manufacturers of today add barium salt (barium carbonate) to their products to wash soluble salts from the base material. In the resultant reaction,
the products are two fairly insoluble compounds: barium sulfate and calcium carbonate. When produced this way, these products have little tendency to efflorese.
Important point: Masonry building products need to be stored in a dry place off the ground. This will prevent prevent absorption of moisture or dampness from soil,
which may contain efflorescent-developing salts.
Evaporation of the salt-bearing water usually occurs below the surface in stucco, concrete and other masonry products because they are so porrous.
Carbon dioxide from the air reacts with the hydroxides causing them to convert to alkali and calcium caronates. If the structure is surrounded by or exposed to salt bearing water
or soil, that's when efflorence appears. Spalling will occur on stucco.
Practically any building
material in direct contact with the earth is a potential for water-soluble
salts. This fact has been recognized by building materials producers and steps
have been taken to reduce their appearance to a substantial degree but it hasn't been discovered yet how to eradicate it permanently.
Remedies for Efflorescence
Let's turn now to some methods commonly used to remove efflorescence which might be helpful to you.
One method is to apply pressurized water. Another method is to apply acid followed by a washing. Two acids that have proven effective are phosphoric acid and muriatic acid.
Phosphoric acid tends to be less corrosive relative to fumes. Fumes from muriatic acid may attack the plated metal and destroy the plating. Diluting the acid with water
is necessary (usually about 5% of acid to water). We recommend hiring professionals as an improper use of acids can cause serious problems.
Go to Part III
Return to Part I
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