GB2147313A

GB2147313A - An electrode arrangement for the desalination and drying of masonry

Info

Publication number: GB2147313A
Application number: GB08424728A
Authority: GB
Inventors: Peter Friese; Hubertus Birkenhofer; Klaus Reckin; Karin Zacharzowsky
Original assignee: Bauakademie der DDR
Current assignee: Bauakademie der DDR
Priority date: 1983-10-04
Filing date: 1984-10-01
Publication date: 1985-05-09
Also published as: HUT40185A; GB2147313B; DK473784A; DK473784D0; GB8424728D0; BE900745A; DE3430449A1; IT8467984A0; AT383170B; NL8402689A; FR2552796A1; BG48633A1; HU192446B; ATA267284A; IT8467984A1; DD234997A3; IT1179140B; FR2552796B3

Abstract

An electrode arrangement for the electro-chemical desalination, followed by electro-kinetic drying, of masonry affected by rising damp, wherein an electrode system is used in which the anode inserted into the masonry comprises an iron bar 1 shaped to ensure that with sufficient mechanical stability an inherently stable layer 2 of calcium hydroxide, calcium carbonate and one or more binding agents can be applied to the bar in such a way that the electrode as a whole is of cylindrical shape, that part of the electrode which extends from the masonry being used for the provision of a contact, while the contact system is protected from discharged iron (III) chloride hydrates and calcium chloride hydrates by a plastic sleeve 3 mechanically connected by a resilient stem 4 with a channel 5 which is impermeable to liquid and by which the iron (III) chloride hydrates and calcium chloride hydrates which form electrochemically flow into a collecting vessel 7. The iron bar 1 may support a layer 2 of the cross-section shown in Figure 2. Alternatively the iron bar may have longitudinal and/or transverse grooves or it may be in the form of a spiral. <IMAGE>

Description

SPECIFICATION Electrode arrangement for the desalination and drying of masonry.

This invention relates to an electrode arrangement for the electro-chemical desalination followed by electro kinetic drying of masonry affected by rising damp. The invention is particularly suitable for the rapid desalination and drying of masonry under production conditions.

Electro-chemical processes for the desalination and drying of masonry exposed for a considerable period to rising damp have been known for some years (DDP 242 340). In such processes corrosionresistant anodes, which may consist of vitreous graphite or platinized titanium rods, are inserted in the masonry in such a manner that the electrodes are embedded in a mixture of calcium hydroxide and calcium carbonate, while a channel impermeable to liquid and serving two discharge the liquid and electro-chemically formed calcium chloride hydrates is provided underneath the electrodes. The calcium chloride hydrates occur as a result of the fact that the chloride ions in the electric field move to the anode. The calcium chloride forming in the anode space, being very hygroscopic, attract water from the surroundings and form calcium chloride hydrates.

In a variant of this process plastic bars with an iron plate as the anode are attached to the masonry from the outside and a damp porous layer with high proportions of calcium hydroxide and calcium are filled in between the masonry and the anode plate.

A great deal of manual labour is involved in the installation of desalination and drying equipment of this kind. With the use of corrosion-resisting anode bars, moreover, the material of which these are made are very expensive, and serious damage is liable to be caused by theft or by damage resulting from other building operations.

This invention seeks to provide an improved electrode arrangement for electro-chemical desalination and drying which can be inserted easily and rapidly into the masonry. An object of this invention is to construct a system of electrodes in such a way that it will operate with less expensive and more easily available materials and at the same time provide a higher desalination and drying speed as well as being usable under the conditions arising in production.

According to this invention there is provided an electrode arrangement for the electro-chemical desalination, followed by electro-kinetic drying, of masonry affected by rising damp, wherein an electrode system is used in which the anode inserted into the masonry comprises an iron bar shaped to ensure that with sufficient mechanical stability an inherently stable layer of calcium hydroxide, calcium carbonate and one or more binding agents can be applied to the bar in such a way that the electrode as a whole is of cylindrical shape, that part of the electrode which extends from the masonry being used for the prdvision of a contact, while the contact system is protected from discharged iron (lli) chloride hydrates and calcium chloride hydrates by a plastic sleeve mechanically connected by a resilient stem with a channel which is impermeable to liquid and by which the iron (III) chloride hydrates and calcium chloride hydrates which form electrochemically flow into a collecting vessel.

In this invention an iron electrode is so designed that an inherently stable layer with the maxuimum possible proportions of calcium hydroxide and calcium carbonate will form on the electrodes, a plastic channel for the discharge of the electrochemically formed calcium chloride hydrates and iron (III) chloride hydrates being directly connected to the electrode via a sleeve. The sleeve at the same time prevents the calcium chloride hydrates or iron (III) chloride hydrates from touching the contact system of the electrode and causing corrosion therein.

The advantage of the invention resides in the fact that the electrodes can be manufactured together with the sleeve and with the channel impermeable to liquid, so that for the installation of a desalination and drying plant it is only necessary to bore holes of the appropriate dimensions in the masonry in order to insert the electrodes. The electrodes cannot be used again, although this is possible in the case of the sleeve with the impermeable channel, provided suitable materials are employed.

An embodiment of the invention is shown by way of illustration in the accompanying drawings and described in conjunction with a practical examples. In the drawings: Figure 1 shows a section through masonry with an electrode structure therein, Figure 2 shows a section on line A-B of Figure 1, and Figure 3 shows a section on line C-D of Figure 1.

For the desalination and drying of a building which has been exposed to rising damp for a number of decades and in which the masonry contains comparatively high proportions of chlorides and soluble sulphates, a desalination and drying plant is installed using industrially prefabricated electrodes which are inserted as anodes into the masonry. The maximum possible direct voltages being applied to one or more earthing bars. The structure of an electrode is shown in the drawings.

The basic core comprises an iron bar 1 of which the upper part is profiled to enable a mixture of calcium hydroxide and calcium carbonate to be applied thereto using a binding agent 2 in such a way that the electrode as a whole is cylindrical in shape, providing adequate mechanical stability.

The drawing shows a possible variant. Other variants are iron bars 1 with longitudinal and/or transverse grooves as well as iron bars 1 which are spiral in shape. The longitudinal and/or transverse grooves and also the spirals are likewise filled with a mixture 2 of calcium hydroxide, calcium carbonate and binding agent, so that here again the electrode as a whole is of the shape of a cylinder. At the end of the electrode l,projecting from the ma sonry, is a plastic sleeve 3 bearing hard against the electrode 1. The sleeve 3 is connected via a resilient stem 4 with a plastic channel 5. The plastic channel 5 is inclined at an angle enabling the iron (III) chloride hydrates and calcium chloride hydrates to flow out. The external closure of the electrode 1 is formed by a cap 6 pressed firmly onto the electrode 1.The collecting vessel 7 for the iron (III) chloride hydrates and calcium chloride hydrates which are discharged is suspended between the cap 6 and the sleeve 3. To enable the electrode system to be introduced into the masonry 2 borings of different diameter are provided. The electrode system is then inserted in the masonry in such a manner that the upper part of the electrode bears hard against it and is held in this position by the stem 4. The electrodes 1 introduced into the masonry are conductively interconnected with the space between the sleeve 3 and the cap 6 being preferably utilized for the provision of the contact.

The sleeve 3 prevents the liquid iron (III) chloride hydrates and calcium chloride hydrates from flowing onto the contact system and destroying it. A direct voltage of about 50 V is applied between the electrode system and one or more earthing rods, the electrodes 1 inserted in the masonry being connected as anodes. After 6 to 12 weeks the masonry is desalinated and electro-kinetically dried: The electrodes 1 are then extracted from the masonry and the remaining holes filled with mortar.

To prevent a renewed rise of water the masonry has to be sealed by other methods, such as by electro-kinetic sealing or by injections of water-repellent substances.

Claims

1. Electrode arrangement for the electro-chemical desalination, followed by electro-kinetic drying, of masonry affected by rising damp, wherein an electrode system is used in which the anode inserted into the masonry comprises an iron bar shaped to ensure that with sufficient mechanical stability an inherently stable layer of calcium hydroxide, calcium carbonate and one or more binding agents can be applied to the bar in such a way that the electrode as a whole is of cylindrical shape, that part of the electrode which extends from the masonry being used for the provision of a contact, while the contact system is protected from discharged iron (III) chloride hydrates and calcium chloride hydrates by a plastic sleeve mechanically connected by a resilient stem with a channel which is impermeable to liquid and by which the iron (lil) chloride hydrates and calcium chloride hydrates which form electrochemically flow into a collecting vessel.

2. Electrode arrangement in accordance with Claim 1, wherein the applied voltage is approximately 50 V.

3. Electrode substantially as described herein and exemplified with reference to the drawings.

4. Method for the electro-chemical desalination and electro-kinetic drying of masonry as described herein and exemplified.