Protecting Your Walls, II by Barbara Jennings
Efflorescence Ruining Your Walls?, Part II Sources of 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 Go to Part III |
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