DE102015115297A1 - Method for laying an anode system for cathodic corrosion protection - Google Patents

Abstract

An anode system (8) for a cathodic protection against corrosion should be able to be laid in a particularly simple, fast and cost-effective manner. For this purpose, a method is specified with the following steps: laminar laying of a number of carbon fiber filaments (10); - Laying at least one primary anode belt (12), such that the primary anode belt (12) in a number of contact areas (18) with the carbon fiber filament (10) is electrically connected; - Connecting the primary anode bands (12) to a primary soda wire (26).

Description

The invention relates to a method for laying an anode system for a cathodic protection against corrosion and the use of a non-metallic tape anode in a two-dimensional anode system for cathodic corrosion protection.

Reinforced concrete structures are an integral part of the infrastructure in almost every country in the world. In addition to residential and working buildings, many busy structures made of reinforced concrete are built, e.g. Parking garages, garages, highways, bridges, tunnels etc. A large number of these structures will be used for 50 to 100 years (and sometimes even longer). However, apart from the mechanical stress, it is above all de-icing salts that are added to the reinforced concrete structures. The deicing salts are usually chloride-containing. Therefore, in combination with water, solutions are created which cause corrosion in the structures. For many structures, therefore, substantial, cost-intensive repair work on the reinforcement must be carried out after only 20-25 years.

For this purpose, the contaminated overlay concrete is usually removed, the reinforcing steel cleaned and provided with a new corrosion protection (for example on a polymer or cement basis). However, the repaired area often lasts only a few years (due to mechanical, thermal, and / or hygric incompatibilities), requiring prompt further repair, even when the cover concrete is heavily stressed. This causes high costs, represents a significant intervention in the structure and not least leads to usage restrictions during the repair

One possibility of suppressing corrosion and ideally preventing it is the cathodic corrosion protection (PPS) of buildings. As a largely non-destructive repair method, cathodic corrosion protection is gaining in importance as an economic repair process for corrosion-endangered or damaged components.

The principle of electrochemical protection (cathodic protection) is to electrically influence the corrosion process of unalloyed or low alloy steels (e.g., reinforcing steel) in an extended electrolyte (soils, seawater, when used in reinforced concrete: concrete) by introducing direct current. The application of this direct current (protection current) causes a shift of the electrochemical potential of the metal to be protected in the negative direction, whereby the metal surface is cathodically polarized and damaging corrosion is prevented.

To impress a protective current, a permanent and corrosion-resistant anode must first be coupled to the concrete and attached to the positive pole of a rectifier serving as a voltage source. The negative pole of the DC voltage is connected to the steel to be protected (with reinforced concrete to the reinforcement). After switching on the DC voltage to be protected steel is cathodically polarized and the steel corrosion largely prevented.

With the help of an inserted reference electrode, the condition of the building, the structure or the pipeline or the corrosion of the steel can be monitored remotely.

For the most uniform and safe corrosion protection, it is desirable that the anode system as large as possible in the vicinity of serving as a cathode steel element, for example, the reinforcing steel, is designed. However, this is hardly feasible with the anode systems used so far, for example when using rod anodes or titanium tape anodes, or it is very difficult to install, as for example when using a reticulated titanium anode. In particular, the application of a reticulated titanium anode to protect a reinforced concrete structure on the concrete is particularly laborious and time-consuming due to the inflexibility of the material.

The invention is therefore based on the object of specifying a method for laying an anode system for cathodic corrosion protection, which can be carried out in a particularly simple, fast and cost-effective manner.

• – flächige Verlegung eines einer Anzahl von Karbonfaserfilamenten;
• – Verlegung mindestens eines Primäranodenbandes, derart, dass das Primäranodenband in einer Anzahl von Kontaktbereichen mit dem Karbonfaserfilament elektrisch leitend verbunden ist;
• – Anschluss der Primäranodenbänder an einen Primäranodendraht.

This object is achieved according to the invention by the method comprising the following steps:

• - surface laying of one of a number of carbon fiber filaments;
• Laying at least one primary anode tape such that the primary anode tape is electrically connected in a number of contact areas with the carbon fiber filament;
• - Connection of the primary ribbons to a primary soda wire.

The invention is based on the consideration that a particularly simple and rapid installation of the anode system can be achieved if the inflexible titanium tapes or reticulated titanium anodes can be dispensed with as far as possible or if the tapes only have to be laid linearly. Since on a surface relocation of the Anodensystems not to be waived, is used in addition to the titanium tapes on a second material, which can be easily and flexibly laid. It was recognized that a carbon fiber filament or a bundle of several carbon fiber filaments, a so-called carbon fiber multifilament, both has sufficient flexibility for laying flat, as well as a sufficiently high electrical conductivity has to be considered as an anode system for cathodic protection. In addition, such a carbon fiber filament by the meter is inexpensive and easily available, whereby a significant cost savings in the construction of an anode system is possible.

To act on the surface laid carbon fiber filament with the protection current, this is electrically connected to a plurality of contact areas with a linearly laid titanium anode band, for example, and this primary anode band is connected to a primary anode wire. This primary anode wire can then be connected to the positive pole of a voltage source as already explained above.

In addition to the use of cathodic corrosion protection in steel structures (such as docks) or pipelines and pipelines, this can also be used in the context of reinforced concrete structures. It is subsequently to equip the reinforced concrete structures with a cathodic corrosion protection or to consider this directly in a new building.

Both for the refurbishment of reinforced concrete structures, when parts of the concrete layer are newly applied and also in the new building, for a particularly simple laying of the carbon fiber filament this is laid on or in the fresh concrete in a preferred embodiment. However, in order to avoid a short circuit between the carbon fiber filament as the anode and the reinforcing steel as the cathode, for example because the carbon fiber filament rests on the reinforcing steel, sufficient spacing of the carbon fiber filaments from the reinforcing steel is achieved by means of an insulating interlayer, for example a glass fiber composite reinforcement.

In particular, when retrofitting an existing reinforced concrete structure with a cathodic corrosion protection, slits are cut or milled in an advantageous embodiment in the concrete, in which the Karbonfaserfilament can be placed. Further increase or enlargement of the concrete layer to cover the anode system is thus avoided.

In alternative or additional preferred embodiment, the carbon fiber filament for fixing to the concrete can also be glued to this. For this purpose, a conductive adhesive can be used, with which the carbon fiber element is fixed in individual points or over the entire area on the concrete. This method can be used in particular in the renovation of old concrete surfaces. For a particularly good contact between the carbon fiber filament and the primary anode tape, the carbon fiber filament is wound in the contact regions around the primary anode tape in a particularly advantageous embodiment. This creates a large number of contacts in these areas, via which the current can be transferred from the primary anode band to the carbon filament.

In order to best protect the contact areas and at the same time to connect the carbon filament and the primary anode tape better electrically together, the contact areas are enclosed in a preferred embodiment with epoxy resin. Due to the shrinkage of the epoxy resin after application, the contact between the carbon filament and the primary anode tape is improved.

For a fixation of the entire anode system or even only parts of the reinforced concrete, this is advantageously covered with a conductive mortar. So it is best protected from external influences.

The carbon filament is designed meandering in an advantageous embodiment, so as to achieve a particularly uniform distribution and to allow a particularly simple contact with the primary anode belt via the meandering arches. Alternatively, however, other installation patterns can be used which are adapted to the place of use. For example, a laying in individual strips is possible, which are designed parallel to each other and connected to each other via the anode tape.

In addition to the use of such cathodic corrosion protection in reinforced concrete structures, it is also possible to protect the corrosion of steel structures, such as pipelines, port facilities.

The advantages achieved by the invention are in particular that a particularly simple and cost-effective application of an anode system is made possible by the use of a carbon fiber filament. The current continues to be passed through linearly laid primary sands, for example, titanium tape, and then over the Contact areas forwarded to the carbon fiber filament and thus distributed over a wide area.

An embodiment of the invention will be explained in more detail with reference to a drawing. Show:

1 a reinforced concrete section with a cathodic corrosion protection,

2 a cross section through the primary anode belt in a contact area in various embodiments,

3 Laying carbon fiber filaments with fiberglass composite reinforcement,

4 a schematic sequence of the method for laying an anode system.

Identical parts are provided with the same reference numerals in all figures.

In the embodiment according to 1 is a reinforced concrete structure 1 shown, wherein the steel reinforcement or reinforcing steel 2 by means of an applied voltage 4 protected against corrosion. Such cathodic corrosion protection becomes necessary because of the passivation of reinforcing steel due to various processes such as carbonation and, in particular, the action of chlorides 2 can be picked up locally. As a result, anodic areas that result in metal dissolution and cathodic areas in which O2 is formed result in overall formation of localized corrosive foci. In cathodic corrosion protection, an electrical voltage is applied between the corroding reinforcement and an anode connected to the component.

The primary protective effect is based on the polarization shifting the electrochemical reaction equilibria enough to suppress the material dissolution in the anodic regions in favor of the cathodic partial reaction.

Another primary protective effect is that even the passive areas of the corroding reinforcement are cathodically polarized, so that the driving force for the corrosion process is missing. While the primary protection effects are very fast, the secondary protective effects, such as the increase in the OH concentration at the reinforcement surface and the depletion of oxygen near the reinforcement, are due to the cathodic reaction and the migration of the negatively charged Cl ions in the direction of the anode, effective later, but then lead to a reduction of the protective current density.

In the embodiment according to 1 was on the existing concrete 6 with reinforcing steel 2 an anode system 8th applied. The anode system 8th includes a carbon fiber filament 10 meandering on the concrete 6 is arranged. In the edge area of this carbon fiber filament 10 , so in the meandering arches are two primary anode bands 12 arranged in the form of titanium tapes. The meandering arcs of the 14 Karbonfaserfilaments 10 wrap the titanium tapes 12 to allow an electrical connection. The titanium bands 12 are via a primary anode wire, not shown, with the positive pole of the voltage source 4 connected. This voltage can be controlled via a remote monitoring system, not shown, so that the state of the building or the reinforced concrete structure can be detected and continuously monitored. The anode system arranged on the concrete 8th is in the embodiment of a conductive mortar 16 covered to protect against external influences and access.

In the embodiments of the 2 is the primary anode band 12 a contact area 18 shown in different versions in cross section.

In the is the carbon fiber filament 10 wrapped primary anode tape 12 in a previously milled or cut slot 20 of the concrete 6 , This slot 20 is in a further step with a grout 16 filled so as to the primary anode belt and also the carbon fiber filament 10 to protect.

Also in This is the carbon fiber filament 10 wrapped primary anode tape 12 in a slot 20 arranged in concrete. In contrast to is the primary anode band 12 and the carbon fiber filament 10 however, in this embodiment of an epoxy resin 22 enclosed. In principle, the use of other resins or even mortar is possible. This protects the primary anode band 12 and the carbon fiber filament 10 in addition and provides due to the shrinkage of the epoxy resin 22 after application for a particularly close contact. To fill the slot and thus to fix the primary anode band 12 is also a grout here 16 used.

The carbon fiber filament 10 wrapped primary anode tape 12 in the is directly on the concrete 6 on. The anode system in this case is coated with a layer of conductive mortar 16 covered so that it is fixed on the concrete. In contrast to becomes the carbon fiber filament 10 wrapped primary anode tape 12 in the before it is covered by conductive mortar with a conductive adhesive 24 fixed to the concrete.

The attachment options for the primary anode belt shown here can also be transferred to the carbon fiber filament. Again, this can be cast in slots in the concrete, with epoxy resin, glued to the concrete or covered with a layer of conductive mortar.

When laying the filaments 10 Care must be taken in fresh concrete that the filaments 10 the steel reinforcement 2 Do not touch or lie too close to it, thus causing a short circuit between the filaments 10 as an anode and steel reinforcement 2 can be avoided as a cathode. In the embodiment of the 3 are therefore the filaments 10 on an insulating fiberglass composite reinforcement 28 arranged. First, the filaments 10 with binders 30 at this fiberglass composite reinforcement 28 attached and then the composite of filament and fiberglass composite reinforcement 28 with other binders 32 at the steel reinforcement 2 , Thus, even in fresh concrete, for example in Neubetonbauwerke, a sufficient spacing of the filaments 10 to the rebar 2 be ensured.

In 4 are schematic illustrations of the individual process steps in the application of an anode system 8th with a carbon fiber filament 10 shown.

Like in the can be seen on the concrete 6 the carbon fiber filament 10 meandered. For this purpose, it is possible that in an upstream step slits are cut or milled into the concrete, in which the carbon fiber filament can be inserted. When laying the carbon fiber filament 10 become the meandering arches 14 deliberately designed wide so that a loose loop of carbon fiber filament 10 arises. The slots can then be filled with grout in order to fix the carbon fiber filament on the concrete for the further steps 6 to have.

In a next step ( ) are the titanium tapes 12 as primary anode in the area of the meandering arches 14 laid. Due to the flat laid carbon fiber filament 10 , it is now possible the titanium tapes 12 linear design. So can on a complex and complicated deformation of the titanium tapes 12 be waived. Again, it is possible that previously appropriate slots in the concrete 6 be incorporated into the the titanium tapes 12 can be sunk.

Subsequently ( ) or even while laying the titanium tapes 12 the loops of the carbon fiber filament become in the area of the meandering arches 14 around the titanium bands 12 wound. This creates contact areas 18 in the area of the meandering arches 14 , about which an electrical connection between the titanium band 12 and the carbon filament 10 arises. These contact areas can now be enclosed, for example, with epoxy resin, so that on the one hand the contact areas 18 be protected and by the shrinkage of the epoxy resin, a higher and secure bond between the carbon fiber filament and the titanium strip 12 arises. Also the possibly existing slots of the titanium tapes 12 can then be filled with grout, making the anode system 8th on the concrete 6 is fixed.

Finally ( ), the titanium tapes are over a primary aeode wire 26 connected to the positive pole of a voltage source, not shown. In this way, a particularly simple, quick to install and cost-effective planar anode system for cathodic corrosion protection in reinforced concrete structures is achieved.

LIST OF REFERENCE NUMBERS

1

 reinforced concrete

2

 rebar

4

 voltage source

6

 concrete

8th

 anode system

10

 Karbonfaserfilament

12

 Primary anode tape

14

 meandering curve

16

 mortar

18

 contact areas

20

 slot

22

 epoxy resin

24

 Glue

26

 Primary anode wire

28

 Glass fiber composite reinforcement

30

 binder

32

 binder

Claims (10)

Method for laying an anode system ( 8th ) for cathodic corrosion protection, comprising the following steps: - laminating a number of carbon fiber filaments ( 10 ); - laying at least one primary anode tape ( 12 ), such that the primary anode band ( 12 ) in a number of contact areas ( 18 ) with the carbon fiber filament ( 10 ) is electrically connected; - Connection of primary anode bands ( 12 ) to a primary anode wire ( 26 ). Method for laying an anode system ( 8th ) according to claim 1, characterized in that in the case of the protection of reinforced concrete structures, the carbon fiber filament ( 10 ) is laid in prepared slots in the concrete. Method for laying an anode system ( 8th ) according to claims 1 to 2, characterized in that the carbon fiber filament ( 10 ) by means of an adhesive ( 24 ) is attached. Method for laying an anode system ( 8th ) according to claim 1, characterized in that in the case of the protection of reinforced concrete structures, the carbon fiber filament ( 10 ) is laid in fresh concrete or mortar. Method for laying an anode system ( 8th ) according to claims 1 to 4, characterized in that the carbon fiber filament ( 10 ) in the contact areas ( 18 ) at least partially around the primary anode band ( 12 ) is wound. Method for laying an anode system ( 8th ) according to claim 1 to 5, characterized in that for the connection of the carbon fiber filament ( 10 ) and the primary anode band ( 12 ) at the contact areas ( 18 ) Epoxy resin ( 22 ) is used. Method for laying an anode system ( 8th ) according to claims 1 to 6, characterized in that the carbon fiber filament ( 10 ) and / or the primary anode tape ( 12 ) with conductive mortar ( 16 ) is covered. Method for laying an anode system ( 8th ) according to claims 1 to 7, characterized in that the carbon fiber filament ( 10 ) is designed meandering. Use of a non-metallic band anode ( 10 ) in a planar anode system ( 8th ) for a cathodic corrosion protection ( 1 ). Use according to claim 9, characterized in that the band anode ( 10 ) comprises a carbonaceous filament.

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