CS248604B1 - The method of elimination of efflorescence on facade surfaces of buildings - Google Patents

Abstract

Efflorescence is removed by washing the facade with water with a low content of dissolved substances, preferably distilled, demineralized, deionized or boiler condensate, during the period when the perimeter structure does not contain liquid water and the temperature of the air and the structure is above the dew point, and subsequent hydropholising of the surface with a composition that creates a coating on the surface and just below the surface of the facade that is insoluble in water after drying. This is followed by the final surface treatment of the facade with a thin-layer treatment of water dispersion type on a polymer-cement, polymer or silicate basis, or solution type on a silicone or acrylic binder basis.

Description

The invention relates to a method for removing and preventing further formation of efflorescence of water-soluble efflorescence salts on the facade surface of building objects, respectively. on facade finishes of the external envelope of these objects.

The formation of efflorescence in water-soluble salts is one of the most serious defects in the external surface treatment of buildings. The cause of these efflorescences is usually the leaching of water-soluble efflorescence, often in a relatively small degree, when the liquid water permeates through the building envelope.

Liquid water enters the structure either by capillary action when the insulation of the perimeter structure against earth moisture is broken or during the formation of condensation zone in the structure, which results in condensation of water vapor diffusing structures during the year mainly in the direction out of the building.

In the first case, i.e. in the case of isolation failure, efflorescence is prevented primarily by repairing the defective insulation and drying the structure, respectively. another way of preventing ground moisture from rising into the structure, for example by the electrosmotic method or by chemical methods. However, the elimination of efflorescence due to condensing water vapor diffusing the structure is very difficult.

If there is a local occurrence of efflorescence that occurs when the efflorescence salt is stored in the structure inhomogeneously, eg in individual bricks, blocks or other elements of which the structure is built, protection is usually carried out by the place where the efflorescence they are provided on the facade with a waterproof coating, such as an asphaltolatex suspension, paint and car paint for structures, etc., through which a new surface treatment is subsequently carried out.

In this case, the efflorescence salt solution does not reach the facade surface through the waterproof barrier. The disadvantage of this method is that the diffusion resistance of the water-treatment complex is extremely increased and the condensed water remains practically enclosed in the structure and then dries very slowly. Therefore, this relatively simple method is not applicable on a large scale.

For large-scale efflorescence, in practice, the only effective way is to take a relatively cost-effective measure which leads to the elimination of the formation of a condensation zone, i. removal of the original surface treatment and its replacement by a surface treatment with significantly lower diffusion resistance for water spring, eg replacement of the spray treatment on a synthetic basis with scraped birch, etc., or by installing an external thermal insulation lining and thus increasing the temperature over the dew point during the whole year. The disadvantages of these measures can be eliminated by using the efflorescence elimination method of the present invention.

It is an object of the present invention to wash the efflorescence salt from the façade surface by washing with low dissolved water, preferably demineralized, distilled or soft, in a period where the perimeter structure is constantly above the dew point and no effluent condensation is condensed with water. the surface of the structure with a significant water-insoluble hydrophobizing agent after drying, which will further prevent liquid water from penetrating the surface of the structure, respectively. of a weak solution of efflorescence washed out of the structure.

The highly effective hydrophobicizing agent is a composition based on, for example, sodium methylsilanolate, mixed alkali metal alkylsilanolates, colloidal silicon dioxide dissolved in water if they provide a water-insoluble protective coating upon drying, or a similar hydrophobic including silicone resins or combinations thereof organic polymers such as silicone-butyl acrylate combinations soluble in organic solvents such as toluene, xylene, ethyl acetate, acetone and the like. The process for eliminating efflorescence according to the present invention is illustrated in the following examples. A highly hydrophobised surface is advantageous to provide a new surface to increase its life.

treatment, preferably 3 low diffusion resistance, eg silicate or polymersilicate paint.

It is also possible to combine the two operations by rinsing with an aqueous hydrophobic composition at least twice as much as is required for simple hydrophobization. In this process, the composition is sprayed on the facade in excess and flows down the surface.

Example!

During the winter season, efflorescence appeared on a prefabricated apartment building with a perimeter jacket made of switched gas-silicate elements, and chemical analysis revealed that these are alkaline sulphates, which got into the gas-silicate as an admixture of power plant fly ash.

The surface treatment of the switched porous concrete elements was carried out by spraying with synthetic resin based on the binder base of the aqueous dispersion of the styrene-acrylate copolymer. The surface finish defect was removed as follows:

The entire shield was rinsed with demineralized water using a conventional garden sprayer. After drying, the surface was hydrophobized by spraying with an aqueous hydrophobic, in this case sodium mefcylsilanolate solution. After this hydrophobic layer had dried, the repair was completed by spraying a dispersion spray paint facade on a binder-based aqueous dispersion of vinyl acetate acrylate copolymer. After this repair, efflorescence on the façade was no longer present for two winter seasons, although the presence of sulphates in the cladding construction was still noted.

Example 2

The older building of the sports hall was finished with a scratched birolite finish. After the reconstruction of the hall, the whole building was equipped with a unifying new surface treatment, spraying thin-layer plaster on the vinyl acetate-acrylate binder base. Shortly after the completion of the new surface treatment, white efflorescence appeared on the facade in the winter months.

The chemical analysis stated that it is efflorescence composed of a combination of alkali sulphates and chlorides, which apparently got into the surface of the original birolite plaster by deposition of flue gases from a nearby power plant. The following procedure was used to correct the fault:

The whole facade was washed and at the same time hydrophobised by rinsing the facade by pressure spraying with a solution of the following composition:

hydrophobic based on a mixture of sodium alkylsilanolates 1 part by weight of collagen solution 30% by weight of dry silica 1 part by weight water softened on an ion exchange filter in a Na ⁺ cycle 8 parts by weight

After the hydrophobized substrate had dried, the final surface treatment was sprayed with a synthetic polyaercement based binder.

Example 3

On the family house was found the formation of efflorescence of sulphate nature, which were caused by the use of poor quality bricks for construction. Surface treatment of the building was carried out by sprayed birolite plaster on the core plaster of the adjusted mortar. Removal of the defect was performed as follows:

The entire Dyxa façade was rinsed by double rinsing with a stream of boiler condensate using a paint sprayer. After drying the surface of the facade the surface was hydrophobized with a solution of methylsiloxane resins, in a mixture of white spirit + toluene and about 4% by weight of dry matter.

Due to the fact that the rinsing of the façade surface was completely removed by rinsing, no further finishing was used. Further efflorescence did not appear on the facade during the next two years, during which the family house was already properly occupied.

The method according to the invention can be used in the repair of all kinds of construction objects, it is simple and inexpensive to operate, wholly eliminating undesirable efflorescence.

Claims (2)

1. A method of eliminating efflorescence on facades of building objects, characterized in that the facade is washed with water with a low content of solutes, preferably distilled, demineralized, deionized or boiler condensate, at a time when the air and structure temperature is above the dew point; the perimeter structure is free of liquid water, followed by hydrophobization of the surface by a solvent solution composition with water or a suitable organic, eg aqueous alkylsilanolate solution, colloidal silica solution or a combination thereof, or a solution of methylsiloxane resins or silicone + acrylate copolymers in a suitable organic solvent creates a hydrophobic coating on the facade surface and in the pores just below the surface, and is preferably followed by a final coating treatment with a spray or thin film coating of the aqueous dispersion type to polymer-cement, polymer or of a silicate base or solution type with an organic solvent on a binder base of silicone, acrylate and the like or a combination thereof. 2. The method of claim 1, wherein the washing and removal of efflorescence is combined with hydrophobization of the surface such that rinsing of the facade is performed with an aqueous hydrophobizing composition at least twice as much as the composition, the aqueous hydrophobizing composition being sprayed on the facade in excess; flows down the facade surface.