EP0612365A1

EP0612365A1 - Process and device for the elimination of humidity in the walls of a building

Info

Publication number: EP0612365A1
Application number: EP93913122A
Authority: EP
Inventors: Roger +Di Gallois
Original assignee: BONNAL Marie; ORTLIEB Mathieu
Current assignee: BONNAL Marie; ORTLIEB Mathieu
Priority date: 1992-06-15
Filing date: 1993-06-14
Publication date: 1994-08-31
Anticipated expiration: 2013-06-14
Also published as: DE69329965D1; WO1993025773A1; ATE199427T1; EP0612365B1

Abstract

Device for the elimination of humidity in the walls of a building, characterized by having a small number of electrodes (10, 48, 64) to be distributed in at least one wall (12, 50, 66) of said building (5, 60) at a height (h &cir& _-h &cir& _') of a few metres above ground level, a ground connection (16, 68) to be inserted in the ground and conducting wires (20, 22) for connecting each electrode (10, 48, 64) and the ground connection (16, 68) to connectors for a source of d.c. current (18), said electrodes and ground connection being respectively connected to pole (-) and to pole (+) of said source (18). The invention also concerns a process characterized in that a continuous electric circuit is established, with negative polarity being applied to the whole building (5, 60) and positive polarity being applied to a ground connection (16, 68).

Description

PROCESS AND DEVICE FOR ELT-MINING THE MOISTURE OF A CONSTRUCTION

The present invention relates to the removal of moisture from the walls of buildings, in particular in the case of old constructions. It relates more particularly to the fight against rising damp from the ground.

Rises in humidity in the walls are at the origin of numerous and important degradations such as the appearance of cracks, blackish spots or even the detachment of interior wall coverings, plaster or exterior restoration, etc.

This phenomenon obviously affects mainly old buildings which did not provide any preventive measure against this humidity. But it is also observed for more recent constructions in very humid regions.

To remedy this problem, the drying process of the walls of a building by electro-osmosis has long been known. This technique consists of implanting a series of electrodes in all the walls to be treated, in a horizontal plane and at a low height (about 30 centimeters) above ground level. These electrodes are connected to each other and also to one or more earth connections. By using specific materials for the wall electrodes and for the earth connections, an electric field of high intensity is created (several tens of millivolts per meter). Under the influence of this field, the water molecules which rose in the walls, due to a cracking or the porosity of the constituent elements of the walls, are then subjected to a downward movement and are therefore pushed back towards the ground. In parallel with this so-called "passive" method, there is also known a so-called "active" method which consists, as previously, in implanting in damp walls, a series of electrodes at a low height relative to the ground level, as well as earth connections in the ground. The difference lies in the fact that a direct current source is provided to supply the installation. Also, the wall electrodes are connected to the positive pole of the current source and the earth electrode (s) are connected to the negative pole of this source.

A variant of this method has been described in document FR-A-1 583 464. It consists in introducing into the walls to be dried, two sets of electrodes one above the other at predetermined distances, the electrodes being connected to each other by an electrical conductor for each of these series. The upper series is then connected to the positive pole of a direct current source and the lower series is connected to the negative pole. This variant eliminates the need for earth connections located in the ground.

Despite the high intensity field involved by these methods, the results obtained have been insufficient, all the more so since it takes several months to be able to observe the onset of drying.

Subsequently, with the aim of improving the efficiency of the electro-osmosis technique, the document FR-A-1 508 872 described the combination of the dewatering method by electro-osmosis with electrophoresis. . To do this, phoresis products are introduced into the recesses in the walls to implant the electrodes. Under the influence of the applied electric field and simultaneously with the phenomenon of electro-osmosis of the water molecules, the ions resulting from the phoresis products migrate in the direction of the displacement of the water. These products are therefore entrained in the capillaries of the walls which are thus closed. Various phoresis products have been described, in particular in document FR-A-2 603 318, in liquid and / or powder form.

However, although the results obtained by coupling electro-osmosis and electrophoresis are significantly better than with electro-osmosis alone, they are not entirely satisfactory and very often residual moisture remains .

In addition, these methods require the use of a very large number of electrodes, namely several hundred per wall, in order to create step by step and as best as possible, a high, continuous and uniform electric field, this that is, several hundred millivolts per meter on all the walls. This results in very high installation costs.

In addition, in most cases, you must wait several months (at least 3 or 4 months) to start observing the disappearance of humidity and the installations must be checked, not only during their installation but also in during operation because their efficiency, already average when the humidity is very high, is not constant. Indeed, it often happens that a certain number of electrodes must be quickly changed because they have become totally ineffective due to their oxidation or an accumulation of derivatives of phoresis products.

The object of the invention is to provide a method and a device for removing moisture from walls which is simple to install, inexpensive and effective quickly and steadily over time.

To this end, the subject of the invention is a method for combating the humidity of the walls of a building, characterized in that a continuous electrical circuit is established, the negative polarity of which is applied to the whole of the building. and whose positive polarity is applied to an earth connection. According to other characteristics of the invention:

- the negative polarity is applied at a height of the order of a few meters above ground level.

- the negative polarity is distributed in a small number of points in at least one wall of the construction.

- we apply the negative polarity at a single point of the construction.

- we apply negative polarity in a massive part of the construction. - we apply the negative polarity in a cross wall of the construction.

- we apply the negative polarity in the most conductive part of a building wall.

The invention also relates to a device for removing moisture from the walls of a building, characterized in that it comprises a small number of electrodes intended to be repatiated in at least one wall of said building at a height of the order of a few meters from the ground level, an earth plug intended to be planted in the ground and conducting wires which must connect on the one hand, each electrode and on the other hand, the earth plug, connectors for a direct current source, respectively at the pole (-) and the pole (+) of said source. According to other characteristics of the invention:

- it includes a single electrode.

- it includes an electrode placed in a cross wall of the construction.

- it includes an electrode in a massive part of the construction. for a wall made with building elements such as concrete blocks, bricks, stones or the like, said device comprises an electrode inserted in one of the joints connecting said building elements. - it includes an electrode inserted into the most conductive part of a building wall. it comprises an electrode placed in a recess having walls covered, at least partially, with a composition based on graphite powder. - the intensity of the electric field created is of the order of a millivolt per meter.

The invention is based on the surprising observation that the intensity of the electric field created is not a determining factor for the desired result, contrary to the teaching that can be drawn from all the methods known up to now.

Indeed, as indicated above, the known methods are based on the application of the most homogeneous electric field possible and the highest possible intensity, which implies the installation of a large number of electrodes for each wall of the same construction.

In addition, we have so far considered a building and the land on which it was built, as a whole and the methods developed have always sought to act on the walls of the building. We thought we could treat with electro-osmosis and / or

Electrophoresis, both construction and land.

However, it has been found that the creation of an electric field of low intensity and not necessarily homogeneous makes it possible to defuse the rising damp coming from the ground on which the building was constructed.

We have discovered, in fact, that it is necessary to differentiate on the one hand, the fine capillaries by which the soil water can rise very high in the walls but in small quantities and on the other hand, the large capillaries which have a higher flow but which are, in parallel, more difficult to initiate. In fact, the water supply to the large capillaries, once started, is maintained by pumping the adjacent fine capillaries. We thus realized that it was necessary to distinguish the "construction environment" from the "field environment" and create an interface between these two environments to act at this level. The invention therefore aims to defuse, as a priority, the lifts by the large capillaries.

Furthermore, not only is the weak field applied according to the invention sufficient, but it leads to reliable long-term and faster results compared to the electro-osmosis / electrophoresis technique, without requiring additional phoresis products and with a particularly limited number of electrodes.

The invention will be better understood with the aid of the description given below by way of illustrative and nonlimiting example as well as of the drawings in which: FIG. 1 is a schematic perspective view of a house equipped with the device according to the invention, showing the positioning of an electrode and the earth connection with respect to the entire construction and with respect to the ground;

- Figure 2 is a partial schematic sectional view of the wall of the house of Figure 1, showing the positioning of the electrode and the earth connection connected to a DC source; Figure 3 is an electrical diagram of a device according to the invention.

- Figures 4a. and 4b are partial schematic views, respectively from the front and in section, of an alternative embodiment of the invention, showing the positioning of the electrode in one of the joints connecting the constituent elements of the wall; Figure 5 is a schematic perspective view of a house comprising a device according to another embodiment of the invention;

- Figure 6 is a partial schematic sectional view of the wall of the house of Figure 5 comprising the electrode, showing the positioning of this electrode facing a cross wall;

- Figure 7 is a schematic sectional view of the house of Figure 5, to illustrate the distribution of the electric field.

The method according to the invention generally consists in subjecting the entire construction to be treated to the action of a low intensity electric field. To do this, a small number of electrodes distributed in the walls of the construction to be treated are used, as described below with reference to FIGS. 1 to 4.

The term “low number of electrodes” is understood to mean the implantation of a single electrode, or even two, three or four electrodes in the case of large buildings. In general, it is necessary to use a number of electrodes more or less large depending on the permeability of the walls and therefore according to the nature and the state of its constituent elements. Experience shows that a single electrode is generally enough to, in a way, transform the construction into a giant electrode. This is the case described below.

FIG. 1 illustrates a device according to the invention applied to an individual house 5 of medium size.

As can be seen in this figure, an electrode 10 is inserted into an exterior wall 12 of said house 5. According to the example shown schematically in Figure 1, the electrode 10 is introduced into an exterior wall on the side exterior to the construction but it is entirely possible to include it on the interior side and even in an interior wall such as a cross wall, as is explained below. In fact, the electrode is placed in order to obtain a good distribution of the electric field created over the entire construction. To set up the electrode 10, a recess 14 (see FIG. 2) is previously made in the wall 12 at the chosen location and the walls of this recess 14 are optionally covered with a conductive varnish based on graphite powder or any other product that improves contact.

The electrode 10 consists, for example, of an expansion bolt or other conductive material such as copper.

A reliable result can be obtained with a conductive electrode of about ten millimeters embedded over two thirds of the thickness of the wall by using a conductive varnish based on graphite powder as mentioned above.

The electrode 10 is placed at a height h. from ground level, about three meters. This height h is, in general, of the order of a few meters and this, unlike known techniques where the electrodes were placed a short distance above the ground, of the order of a few tens of centimeters.

Furthermore, an earth plug 16 is planted in the ground. Here, the earth electrode 16 is advantageously placed at a distance d _. relative to the foot of the wall 12, of the order of a few tens of centimeters. Finally, a direct current source 18 is provided.

(not shown in FIG. 1) to which the electrode 10 and the earth electrode 16 are connected, as shown in more detail in FIG. 2.

Referring now to FIG. 2, it can be seen more precisely that the electrode 10 is connected to the negative pole of the direct current source 18, by an electrical conductor 20 and the earth connection 16 to the positive pole. from this source 18, by another electrical conductor 22.

A closed electrical circuit is thus established between the electrode 10, the earth electrode 16, the direct current source 18 and the wall 12. It is noted that, according to the invention, the application of the polarities is reversed compared to the prior techniques. This is due to the fact that we consider the construction and the land on which it is built as two distinct environments; we create an interface between these two media and we act, by applying an electric field, at this interface. The basic principle of the invention is therefore completely contrary to that of the methods known up to now since, according to these, the construction and the land were considered to form a single medium and one acted exclusively on the walls. whether by electro-osmosis alone or combined with electrophoresis.

The choice of the type of DC source 18 is often influenced by both commercial and practical considerations.

It can be, for example, a mains supply with one or more rechargeable batteries, as indicated in Figure 3. If we refer to the electrical diagram of the figure

3, it can be seen that the device according to the invention is supplied by a high voltage alternating current source 30. An isolation transformer 32 and a rectifier bridge 34 are provided to obtain a low voltage direct current. In the case considered here, the device comprises a rechargeable battery 36 connected to an earth connection 38. Such a device can therefore operate in the following two ways:

- Channels VI and VI which constitute two parallel channels according to which the electrode 10 is supplied by a direct current source derived from a mains supply. According to channel VI, the electrode 10 is directly supplied by the low-voltage direct current coming from the rectifier bridge 34, via a diode 40. According to channel VI, the electrode 10 is supplied and the battery is charged. 36. In this case, a charge regulator 42 and a diode 44 are provided. - The channel V2 by which the electrode 10 is supplied by the battery 36, via the diode 44.

This device has the advantage of being able to operate on the mains or on the battery when there is an involuntary or voluntary power cut, for example for dwellings which are not regularly occupied.

In other cases, the DC source 18 consists, for example, of commercially available 1.5 volt batteries. For a medium-sized detached house, for example, two batteries are enough for an autonomy of at least six months.

It is also possible to replace the mains supply by the use of solar photo-batteries, in particular for buildings which are occupied only sporadically and not regularly. The primary power source in this case having a certain randomness and which may be subject to discontinuities, provision is advantageously made for the presence of a buffer storage battery.

The intensity of the current is chosen according to the importance of the construction to be treated and of the material of the walls. Indeed, the more compact the material constituting the walls, that is to say for example walls made of bricks or stones linked by a rich cement, the more a low current can be applied. On the contrary, if the walls are made of millstones assembled with a poor mortar, an electric current of higher intensity is applied because the fine capillaries are then more numerous than in the first case.

The vertical component of the established electric field is of the order of a millivolt per meter at the base of walls, whatever their nature. It should be noted that this vertical component is notably less than that of the electric fields applied according to the electro¬ osmosis and / or electrophoresis methods. In addition, the conductivity of the wall varies with its humidity level depending on the presence of underground sources, heavy rainfall, etc. , and there is therefore a self-regulation of the current whose intensity increases with an increase in the humidity rate and decreases when it also decreases, for a relatively constant field.

It should be noted that, given the specific positioning of the electrode at a height h_ of at least ten times greater than the height of the electrodes currently implanted, the influence of the electric field created is much more extensive than in the case of the techniques. anterior and it is the set of construction walls that is subjected to the action of said electric field. In addition, the electrode is placed in a part of a wall supposed to be the most conductive.

Figures 4a _. and 4b illustrate the case where the wall 50 having to receive the electrode 48 is made of concrete blocks, bricks, stones 52 or other building elements connected to each other by a mortar or a cement serving as joints to form the wall. The electrode 48 is then preferably placed in one of the seals 54 connecting the elements 52.

FIGS. 5 and 6 illustrate, for their part, the case of a construction 60 comprising a cross wall 62. An electrode 64 is then inserted, preferably in the immediate vicinity of this wall 62 or even in the cross wall itself. 'It has a thickness greater than that of the exterior walls in order to be placed in the most massive part of the construction. Here, the electrode 64 is introduced into an exterior wall 66 facing the cross wall 62. This further improves the diffusion and distribution of the electric field.

In Figure 5, we see that the electrode 64 is placed at a height &'of about three meters. In addition, an earth plug 68 is planted in the ground. It is advantageously placed at a point distant from a wall construction exterior. Finally, a direct current source (not shown) of the aforementioned type is provided to form a closed circuit with the wall 62, the electrode 64 and the earth electrode 68 similar to that shown diagrammatically in FIG. 2.

The vertical component of the electric field created is maximum below the electrode 64 (point A) and decreases as one moves away from it.

The values of the vertical component of the electric field created, at the different points indicated in Figure 7, are as follows:

Point A 2.5 mV / m

Point B 1.5 mV / m

Point C 1.1 mV / m Point D 0.7 mV / m

Point E 1 mV / m Point F 0.5 mV / m Point G 1.1 mV / m These measurements were taken approximately twenty centimeters above ground level and are expressed in millivolt per meter (mV / m).

It is thus observed that the small potential difference which exists at the base of the walls (including the floors in the absence of crawl space), that is to say at the wall / floor interface, is sufficient for reactions occur in this area. We can say in a way, that we transform into a huge electrode, on the one hand, the whole construction and on the other hand, the ground on which the construction is located. Also, the walls play the role of cathode. Everything seems to happen as if we had an in situ electrophoresis of components present in the soil and in particular a displacement of the gases occluded in the soil. The clogging of the cracks in the walls is thus observed very quickly thanks to the gaseous molecules, and a "defusing" of the phenomenon of rising in the walls, of moisture coming from the ground is then obtained. It can be noted that the basis of the invention and consequently, the device and the method which have just been described, are entirely contrary to the teaching of the prior art, because the latter advocated the application, step by step, of an electric field of high intensity, continuous and homogeneous on each of the walls to be dried, including the interior walls, which necessitated, consequently, the installation of a very large number of electrodes, on the order of several hundred. According to known methods, it was sort of implanting electrodes in a medium (construction and land) while according to the invention, each medium is transformed separately into a huge electrode (on the one hand, the construction and on the other hand, the field).

Claims

R E V E N D I C A T I O N S

1 / Method for combating the humidity of the walls of a building, characterized in that a continuous electrical circuit is established, the negative polarity of which is applied to the whole of the building (5-60) and the polarity of which positive is applied to a ground (16-68).

2 / A method according to claim 1, characterized in that σue is applied negative polarity at a height d _l -h ') of the order of a few meters above ground level.

3 / A method according to claim 1, characterized in that the negative polarity is distributed in a small number of points (10-48-64) in at least one wall (12-50-66) of the construction (5- 60).

4 / A method according to claim 3, characterized in that the negative polarity is applied at a single point (10-64) of the construction (5-60).

5 / A method according to claim 1, characterized in that the negative polarity is applied in a massive part of the construction (5-60).

6 / A method according to claim 1, characterized in that one applies the negative polarity in a cross wall (62) of the construction (60).

7 / A method according to claim 1, characterized in that one applies the negative polarity in the most conductive part of a wall (12-50-66) of the construction (5-60).

8 / Device for removing moisture from the walls of a building, characterized in that it comprises a small number of electrodes (10-48-64) intended to be distributed in at least one wall (12-50- 66) of said construction (5-60) at a height (h-h ') of the order of a few meters from the ground level, an earth plug (16-68) intended to be planted in the ground and conductive wires (20-22) to connect on the one hand, each electrode (10-48-64) and on the other hand, the earth connection (16-68), to connectors for a direct current source (18), respectively at the pole (-) and the pole (+) of said source (18).

9 / Device according to claim 8, characterized in that it comprises a single electrode (10-64).

10 / Device according to claim 8, characterized in that it comprises an electrode (64) placed in a cross wall (62) of the construction (60).

11 / Device according to claim 8, characterized in that it comprises an electrode (48) in a massive part of the construction (5-60).

12 / Device according to claim 11, characterized in that for a wall (50) made with building elements (52) such as concrete blocks, bricks, stones or the like, said device comprises an electrode (48) inserted in one of seals (54) connecting said construction elements (52).

13 / Device according to claim 8, characterized in that it comprises an electrode (10-48-64) inserted in the most conductive part of a wall (12-50- 66) of the construction (5-60) .

14 / Device according to claim 8, characterized in that it comprises an electrode (10) placed in a recess (14) having walls covered, at least partially, with a composition based on graphite powder.

15 / Device according to claim 8, characterized in that 1 • intensity of the electric field created is of the order of a millivolt per meter.