CH684796A5 - Method of protection for ensuring the longevity of concrete structures - Google Patents

Abstract

A process for protection intended to ensure the longevity of structures made of concrete, by an economical impregnation system which is easy to produce, controllable and renewable, improving especially the hardness and the leaktightness of surface mortars with the aid of hydrofluoric acid salts or of alkali metal silicates etc.

Description

1

CH 684 796 A5

2

Description

The deterioration of reinforced concrete constructions often leads to very costly remediation.

Without speaking about the destructive effects of certain specific aggressive agents, the simple exposure to ordinary climatic agents is enough to cause corrosion phenomena of the reinforcements when these are not sufficiently protected. The basic cover of the original concrete can be reduced by carbonation. The free lime contained in ordinary portland cement then gradually disappears and, in the long term, the reinforcements are exposed to rust like any unprotected iron. Carbonated concrete also becomes more and more porous and, by the same token, more and more sensitive to attacks from the surrounding environment.

This phenomenon can be rapid if the concrete cover on the irons is weak, if the concrete is not very compact or if the stresses of the medium are very restrictive.

It is therefore important to ensure LONGEVITY in concrete construction. As one can practically often not guarantee the quality and the constancy of the execution in all points of the construction and as one is - most of the time - not master of the characteristics of the surrounding environment, one tends more and more more to protect the surface of the concrete by various plasters or paints, even by insulations or cladding.

Most of these methods are very expensive. Some of them are still poorly understood and their durability remains questionable. Others, by concealing the concrete facing, do not allow monitoring the condition of the structure itself.

The present invention makes it possible to appreciably improve the quality of the surface of concrete by creating a reinforced facing, much better resistant to attack by the external environment. It also offers the advantage:

- to be very economical

- to be easy to apply

- to allow constant monitoring of the treated surfaces left visible

- to be able to be renewed in the long term, when it becomes necessary (generally around ten years, under normal conditions, outside).

According to the present invention, after preparation of the support, a transparent impregnation is carried out, in several successive phases (3 in general), 24 hours apart if possible, from the concrete surface to be protected by a solution (1/3 approximately) of hydrofluoric acid salts or fluosilicic salts of magnesia MgSiF6 or of alkali silicates (water glass 38 ° Bé). The siding thus treated must be rinsed with clean water after the first applications and washed with plenty of water (but without pressure) after the last.

Professor Sarrasin's research and experience have shown that the combination of the recommended impregnation and mortars forms a surface layer of practically insoluble concrete, of great hardness and with very good resistance to common chemical attack.

This process is suitable for protecting exterior siding as for improving the waterproofness of concrete and the resistance to detergents, acids or oils, for example floor slabs. In the latter case, one can easily record the very low consumption of the impregnation product, which must be, for a support in good condition, from 0.12 to 0.25 liters per m2.

New concrete surfaces should be treated as soon as possible after setting the concrete. Old or dirty surfaces should be cleaned thoroughly, then rinsed in cold water and thoroughly dried before treatment.

Before impregnation, all the surfaces to be treated will be carefully brushed and washed with plenty of water to remove the dust which would prevent the penetration of the impregnation and adversely affect the adhesion between the solution and the concrete.

Impregnation can be easily carried out by careful personnel, but without any particular qualifications, using brushes or paintbrushes, for example. We can also consider other modes of application, using projection techniques, if the size of the surfaces to be treated justifies it.

During treatment, operators must wear protective clothing and in any case suitable glasses. Untreated windows or openings will be masked or coated with a greasy film allowing subsequent cleaning.

Claims (8)

Claims 1. A method of protecting concrete surfaces, improving sealing, surface hardness and resistance to climatic and chemical attack, characterized in that protection is obtained by impregnating the concrete with a solution of acid salts hydrofluoric. 2. Method according to claim 1, characterized in that the protection is obtained by impregnating the concrete with a solution of fluosilicon salts of magnesia of formula MgSiF6. 3. Method for protecting concrete surfaces, improving sealing, surface hardness and resistance to climatic and chemical attack, characterized in that protection is obtained by impregnating the concrete with a solution of alkali silicates, soluble glass 38 ° Be. 4. Method according to one of the preceding claims, characterized in that the impregnation is carried out in 2 or 3 successive phases, preferably 24 hours apart. 5. Method according to one of the preceding claims, characterized in that the impregnation is preceded by a preparation of the support by brushing, washing and drying. 6. Method according to one of the preceding claims, characterized in that the impregnation is followed by a rinsing to be carried out just before its complete drying. 7. Method according to one of the preceding claims - 5 10 15 20 25 30 35 40 45 50 55 60 65 2 3 CH 684 796 A5 teeth, characterized in that the solution is made in a proportion close to 1 (salts): 3 (water). 8. Method according to one of the preceding claims, characterized in that the amount of solution to be applied to a flat surface is 0.12 to 0.25 liters per m2, for each impregnation. 5 10 15 20 25 30 35 40 45 50 55 60 65 3