Efflorescence

The bloom, also called efflorescence, one of the structural damage and refers to the crystallization of salts on the structure surface.

Causes

If water penetrates into a building one (see Mauertrockenlegung ), it dissolves in mineral building materials (concrete, mortar, brick, clinker ) soluble salts out, especially potassium and sodium sulfate, and diffuses through the building. Dries then from the building, the dissolved salts remain on the building surface and crystallize there. Crystallization occurs an increase in volume, which leads to the "blooming" and blasting the plaster. The result is unsightly, usually white raised spots on the structure ( outside) envelope.

Another cause can crystallizing nitrates (so-called " saltpeter " ), such as calcium nitrate ( " Mauersalpeter " ) may be occurring by reaction of excrement ( for example, animals ) or ammonia from the air with mortar:

• In (former) livestock buildings
• When animals were held for times of famine in living rooms,
• In shelter use in emergency and wartime for the population, including livestock,
• In case of misuse of residential, storage or sacred spaces as an animal stable,
• After wintry together of the house and stable residents (cattle, pigs, goats, dogs and chickens, etc.) in heated rooms
• By backward splash, animals were kept as still ubiquitous on the street or the contents of the chamber pot was emptied onto the street,
• After a backpressure
• Due to contamination by curing salts and solutions ( brines )
• Use a laundry room ( in the basement) as a slaughterhouse or Gedärmreinigung
• In abortions

Because calcium nitrate significantly more soluble in water than lime mortar can lead to wash out the walls and to the destabilization of the masonry.

Today's malicious salt sources are:

• Cement, trass and silicate - containing construction materials
• Many Injektagematerialien
• The control of dry rot or mold
• Carbonate -silicate cycle and silicate weathering
• Propellant reactions of electric plaster with cement mortar

Through dissolved in water splash icing salt efflorescence may also occur.

Protection measures

In order to prevent efflorescence permanently, the moisture sensitive materials ( through active wall drainage, drainage channels and pit against unintentional slack water ) must be prevented. In addition, must be eliminated ( in the plaster by knocking off the plaster ) nitrate supplies.

For desalination of masonry exist several techniques:

• Auswaschtechnik,
• Kompressentechnik or victims brushing technique ( with salt receiving compresses, eg from cellulose compounds or bentonite - sand mixture ), with kapillaraktivem Luftkalkmörtel

With the help of impregnating the pores can be closed and the penetration of moisture is prevented, however, by other salts are introduced into the structure. Another protective measure is water-repellent. These are substances known to occupy the inner pore and capillary surfaces and thus make them water-repellent ( hydrophobic). Since the pores and capillaries are thus not closed, the diffusivity ( vapor permeability ) of the building material will remain virtually unchanged.

If you can not prevent the moisture, eliminates one efflorescence best by scraping or brushing. In many cases restoration plasters are applied to the previously cleaned from salt- permeated plaster surface.