METHOD FOR LAYING AN ANODE SYSTEM FOR CATHODIC CORROSION PROTECTION

Abstract

An anode system for cathodic corrosion protection should be able to be laid in a simple, quick and cost-effective manner. For this purpose, a method comprising the following steps is provided: laying a carbon fibre multifilaments in a planar and meandering or strip-shaped manner; laying at least two primary anode ribbons, which are arranged so as to be spaced apart from one another, such that the carbon fibre multifilament is arranged between the primary anode ribbons and the primary anode ribbons are connected to the carbon fibre multifilament in an electrically conductive manner in a number of contact regions.

Claims

1. Method for laying an anode system for cathodic corrosion protection, comprising the following steps: laying a carbon fibre multifilament in a planar manner; laying at least two primary anode ribbons, which are arranged so as to be spaced apart from one another, such that the carbon fibre multifilament is arranged between the primary anode ribbons and the primary anode ribbons are connected to the carbon fibre multifilament in an electrically conductive manner in a number of contact regions, characterised in that, the carbon fibre multifilament is arranged in a meandering configuration or in individual strips that are arranged in parallel with one another and that are interconnected by the anode ribbon.

2. Method for laying the anode system according to claim 1, further comprising connecting the primary anode ribbons to a primary anode wire.

3. Method for laying the anode system according to claim 2, characterised in that, in the case of protecting reinforced concrete structures, the carbon fibre multifilament is laid in prepared grooves in concrete.

4. Method for laying the anode system according to claim 3, characterised in that the carbon fibre multifilament is fastened by means of an adhesive.

5. Method for laying the anode system according to claim 1, characterised in that, in the case of protecting reinforced concrete structures, the carbon fibre multifilament is laid in fresh concrete or mortar.

6. Method for laying the anode system according to claim 5, characterised in that the carbon fibre multifilament is wound at least in part around the primary anode ribbon in the contact regions.

7. Method for laying the anode system according to claim 6, characterised in that epoxy resin is used to connect the carbon fibre multifilament and the primary anode ribbon in the contact regions.

8. Method for laying the anode system according to claim 7, characterised in that the carbon fibre multifilament and/or the primary anode ribbon is covered with a conductive mortar.

9-10. (canceled)

11. Method for laying the anode system according to claim 1, characterised in that, in the case of protecting reinforced concrete structures, the carbon fibre multifilament is laid in prepared grooves in concrete.

12. Method for laying the anode system according to claim 1, characterised in that the carbon fibre multifilament is fastened by means of an adhesive.

13. Method for laying the anode system according to claim 1, characterised in that the carbon fibre multifilament is wound at least in part around the primary anode ribbon in the contact regions.

14. Method for laying the anode system according to claim 1, characterised in that epoxy resin is used to connect the carbon fibre multifilament and the primary anode ribbon in the contact regions.

15. Method for laying the anode system according to claim 1, characterised in that the carbon fibre multifilament and/or the primary anode ribbon is covered with a conductive mortar.

16. Method for laying the anode system according to claim 1, characterised in that the carbon fibre multifilament is arranged in the meandering configuration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] An embodiment of the invention will be described in greater detail with reference to the drawings, in which:

[0030] FIG. 1 shows a detail of reinforced concrete comprising cathodic corrosion protection,

[0031] FIG. 2 is a cross-section through the primary anode ribbon in a contact region in various embodiment variants,

[0032] FIG. 3 shows carbon fibre multifilaments being laid with glass fibre composite reinforcement,

[0033] FIG. 4 schematically shows the sequence of the method for laying an anode system.

DETAILED DESCRIPTION

[0034] Identical parts are provided with the same reference signs in all figures.

[0035] In the embodiment according to FIG. 1, a reinforced concrete structure 1 is shown, the steel reinforcement or reinforcement steel 2 being protected from corrosion by means of an applied voltage 4. Cathodic corrosion protection of this kind is necessary, since, due to various processes, such as carbonation, and in particular due to the effect of chlorides, the passivation of the reinforcement steel 2 can locally be reversed. As a result, anodic regions, which result in metal dissolution, and cathodic regions, in which O2 is formed, are produced, which overall leads to the formation of local corrosion sites. During cathodic corrosion protection, an electrical voltage is applied between the corroding reinforcement and an anode connected to the component.

[0036] The primary protective effect is based on the electrochemical reaction equilibria being shifted on account of the polarisation until the material dissolution in the anodic regions is suppressed in favour of the cathodic partial reaction.

[0037] Another primary protective effect arises from the passive regions of the corroding reinforcement also being cathodically polarised, such that the driving force for the corrosion process is absent. While the primary protective effects materialise very quickly, the secondary protective effects, such as the rise in OH concentration on the reinforcement surface or the depletion of oxygen in the vicinity of the reinforcement as a result of the cathodic reaction and the migration of negatively charged Cl ions towards the anode, come into effect later, but then lead to a reduction in the protective current density.

[0038] In the embodiment according to FIG. 1, an anode system 8 is applied onto the existing concrete 6 comprising reinforcement steel 2. The anode system 8 in this case comprises a bundle of carbon fibre filaments, referred to as a carbon fibre multifilament 10, which is arranged in a meandering configuration on the concrete 6. In the edge region of said carbon fibre multifilament 10, i.e. in the region of the meanders, two primary anode ribbons 12 in the form of titanium ribbons are arranged. The meanders 14 of the carbon fibre multifilament 10 wind around the titanium ribbons 12 so as to make an electrical connection possible. The titanium ribbons 12 are connected to the positive terminal of the voltage source 4 via a primary anode wire (not shown). In this case, said voltage can be checked by a remote monitoring system (not shown), such that the state of the structure or reinforced concrete construction can be detected and continuously monitored. In the embodiment shown, the anode system 8 arranged on the concrete is covered by a conductive mortar 16 in order to protect it from external influences and access.

[0039] In the embodiments of FIG. 2, the primary anode ribbon 12 in a contact region 18 is shown in cross-section in a variety of embodiments.

[0040] In FIG. 2a, the primary anode ribbon 12 around which the carbon fibre multifilament 10 is wound is located in a previously milled or cut groove 20 in the concrete 6. Said groove 20 has been filled with a grouting mortar 16 in a further work step in order to protect the primary anode ribbon and also the carbon fibre multifilament 10.

[0041] In FIG. 2b, the primary anode ribbon 12 around which the carbon fibre multifilament 10 is wound is also arranged in a groove 20 in the concrete. However, in contrast with FIG. 2a, in this embodiment the primary anode ribbon 12 and the carbon fibre multifilament 10 are encased in an epoxy resin 22. However, in principle, the use of other resins or even mortar is also possible. This additionally protects the primary anode ribbon 12 and the carbon fibre multifilament 10 and produces particularly close contact on account of the shrinkage of the epoxy resin 22 after application. In order to fill the groove and to thus secure the primary anode ribbon 12, a grouting mortar 16 is also used in this case.

[0042] In FIG. 2c, however, the primary anode ribbon 12 around which the carbon fibre multifilament 10 is wound lies directly on the concrete 6. The anode system is in this case covered with a layer of conductive mortar 16 such that it is secured on the concrete. In contrast with FIG. 2c, in FIG. 2d, the primary anode ribbon 12 around which the carbon fibre multifilament 10 is wound is secured to the concrete by means of a conductive adhesive 24 before it is covered by the conductive mortar.

[0043] The fastening options for the primary anode ribbon shown here can also be applied to the carbon fibre multifilament. Said carbon fibre multifilament can also be inserted in grooves in the concrete, encased in epoxy resin, adhesively bonded to the concrete or covered in a layer of conductive mortar.

[0044] When laying the filaments 10 in fresh concrete, care must be taken to ensure that the filaments 10 do not touch the steel reinforcement 2 or lie too closely thereto, such that a short circuit between the filaments 10 as the anode and the steel reinforcement 2 as the cathode can be prevented. In the embodiment according to FIG. 3, the filaments 10 are thus arranged on an insulating glass fibre composite reinforcement 28. In this case, the filaments 10 are firstly fastened to said glass fibre composite reinforcement 28 using ties 30 and then the combination of filament and glass fibre composite reinforcement 28 is fastened to the steel reinforcement 2 using additional ties 32. In this way, sufficient spacing between the filaments 10 and the reinforcement steel 2 can also be ensured in fresh concrete, for example in new-concrete structures.

[0045] In FIG. 4, the individual method steps for applying an anode system 8 comprising a carbon fibre multifilament 10 are shown in schematic drawings.

[0046] As shown in FIG. 4a, the carbon fibre multifilament 10 is applied onto the concrete 6 in a meandering configuration. For this purpose, it is possible for grooves to be cut or milled into the concrete in a previous work step, into which grooves the carbon fibre multifilament 10 can be inserted. When laying the carbon fibre multifilament 10, the meanders 14 are intentionally broad, such that a loose loop of carbon fibre multifilament 10 is formed. The grooves can then be filled with grouting mortar in order for the carbon fibre multifilament to be secured to the concrete 6 for the additional work steps.

[0047] In a subsequent work step (FIG. 4b), the titanium ribbons 12, as the primary anode, are laid in the region of the meanders 14. On account of the planarly laid carbon fibre multifilament 10, it is possible to arrange the titanium ribbons 12 in a linear manner. In this way, costly and complicated shaping of the titanium ribbons 12 can be dispensed with. In this case, too, it is possible for grooves to be made in the concrete 6 beforehand, into which grooves the titanium ribbons 12 can be recessed.

[0048] Subsequently (FIG. 4c) or even while the titanium ribbons 12 are being laid, the loops of the carbon fibre multifilament are wound around the titanium ribbons 12 in the region of the meanders 14. This produces contact regions 18 in the region of the meanders 14 via which an electrical connection between the titanium ribbon 12 and the carbon fibre multifilament 10 is established. Said contact regions can, for example, be encased in epoxy resin such that the contact regions 18 are protected and such that, on account of the shrinkage of the epoxy resin, a stronger and more secure bond between the carbon fibre multifilament 10 and the titanium ribbon 12 is produced. If present, the grooves for the titanium ribbons 12 may subsequently also be filled with grouting mortar, as a result of which the anode system 8 is secured to the concrete 6.

[0049] Finally (FIG. 4d), the titanium ribbons are connected to the positive terminal of a voltage source (not shown) via a primary anode wire 26.

[0050] In this way, a particularly simple, quick-to-lay and cost-effective planar anode system for cathodic corrosion protection in reinforced concrete structures is achieved.

LIST OF REFERENCE SIGNS

[0051] 1 reinforced concrete [0052] 2 reinforcement steel [0053] 4 voltage source [0054] 6 concrete [0055] 8 anode system [0056] 10 bundle as carbon fibre filaments [0057] 12 primary anode ribbon [0058] 14 meander [0059] 16 mortar [0060] 18 contact regions [0061] 20 groove [0062] 22 epoxy resin [0063] 24 adhesive [0064] 26 primary anode wire [0065] 28 glass fibre composite reinforcement [0066] 30 tie [0067] 32 tie