U.S. patent application number 15/759141 was filed with the patent office on 2019-04-25 for method for laying an anode system for cathodic corrosion protection.
The applicant listed for this patent is Detlef Koch. Invention is credited to Detlef Koch, Majid Mahjoori.
Application Number | 20190119819 15/759141 |
Document ID | / |
Family ID | 56979530 |
Filed Date | 2019-04-25 |
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United States Patent
Application |
20190119819 |
Kind Code |
A1 |
Koch; Detlef ; et
al. |
April 25, 2019 |
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.
Inventors: |
Koch; Detlef; (Kreuztal,
DE) ; Mahjoori; Majid; (Siegen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Koch; Detlef |
Kreuztal |
|
DE |
|
|
Family ID: |
56979530 |
Appl. No.: |
15/759141 |
Filed: |
September 12, 2016 |
PCT Filed: |
September 12, 2016 |
PCT NO: |
PCT/EP2016/071458 |
371 Date: |
December 14, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23F 13/20 20130101;
C23F 13/16 20130101; C23F 13/10 20130101; C23F 13/06 20130101; C23F
2201/02 20130101 |
International
Class: |
C23F 13/10 20060101
C23F013/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2015 |
DE |
10 2015 115 297.5 |
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
RELATED APPLICATIONS
[0001] This patent application is a 35 U.S.C. .sctn. 371 national
phase filing of International Application No. PCT/EP2016/071458,
filed Sep. 12, 2016, which claims priority to German Patent
Application No. 10 2015 115 297.5, filed Sep. 10, 2015, the
disclosures of each of which are hereby incorporated herein by
reference in their entireties.
TECHNICAL FIELD
[0002] The invention relates to a method for laying an anode system
for cathodic corrosion protection and to the use of a non-metal
ribbon anode in a planar anode system for cathodic corrosion
protection.
BACKGROUND
[0003] Structures made of reinforced concrete are integral
components of the infrastructure in almost all countries in the
world. In addition to residential and work buildings, many
reinforced concrete structures that are driven on are also
constructed, e.g. multi-storey car parks, garages, motorways,
bridges, tunnels, etc. A large number of these structures have been
used for 50 to 100 years (and sometimes even longer). However, said
reinforced concrete structures are exposed not only to mechanical
stress but in particular to de-icing salts. De-icing salts
generally contain chloride, which, in conjunction with water,
produces solutions that trigger corrosion in the structures.
Substantial, cost-intensive repair work of the reinforcement must
therefore be carried out for many structures after only 20-25
years.
[0004] For this purpose, the contaminated covering concrete is
usually removed, the reinforcement steel is cleaned and provided
with new corrosion protection (e.g. based on a polymer or cement).
However, the repaired region often lasts only a few years (on
account of mechanical, thermal and/or hygric incompatibilities),
and therefore timely further repair is required precisely when the
covering concrete is put under heavy stress. This incurs high
costs, entails significant intervention in the structure and not
least results in usage restrictions during repair work.
[0005] One option for reducing, and ideally preventing, corrosion
is to use cathodic corrosion protection (CCP) in structures. As a
largely destruction-free repair method, cathodic corrosion
protection is gaining importance as an economical repair process
for components that are at risk of or have been damaged by
corrosion.
[0006] The principle of the electrochemical protection method
(cathodic corrosion protection) involves electrically influencing
the corrosion process in unalloyed or low-alloy steels (e.g.
concrete reinforcement steel) in an extensive electrolyte (floors,
seawater, when used in reinforced concrete: concrete) by
introducing a direct current. Applying said direct current
(protective current) causes a shift in the electrochemical
potential of the metal to be protected in the negative direction,
as a result of which the metal surface is cathodically polarised
and damaging corrosion is prevented.
[0007] In order to impress a protective current, a durable and
corrosion-resistant anode must firstly be coupled to the concrete
and fitted to the positive terminal of a rectifier that serves as
the voltage source. The negative pole of the direct current is
connected to the steel to be protected (in reinforced concrete, to
the reinforcement). After switching on the direct current, the
steel to be protected is cathodically polarised and steel corrosion
is largely prevented.
[0008] By using an incorporated reference electrode, the state of
the building, structure or piping and/or the corrosion of the steel
can furthermore be monitored remotely.
[0009] For corrosion protection that is as uniform as possible and
also safe, it is desirable for the anode system to be laid out over
as large an area as possible in the vicinity of the steel element
functioning as the cathode, for example the reinforcement steel.
However, this is hardly possible with anode systems used to date,
for example when using rod anodes or titanium ribbon anodes, or is
very hard to install, for example when using a reticular titanium
anode. In particular, applying a reticular titanium anode to the
concrete in order to protect a reinforced concrete structure is
particularly work-intensive and time-consuming on account of the
inflexibility of the material.
[0010] CCP-Systems are known from the publications WO 92/11399 A1,
WO 99/19540 A1, EP 1 318 247 A1 and US 2014/251793 A1, for
example.
[0011] The object of the invention is therefore to provide a method
for laying an anode system for cathodic corrosion protection that
can be carried out in a particularly simple, quick and
cost-effective manner.
SUMMARY
[0012] This object is achieved according to the invention in that
the method comprises the following steps: [0013] laying a carbon
fibre multifilaments in a planar manner; [0014] 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;
[0015] connecting the primary anode ribbons to a primary anode
wire.
[0016] The invention is based on the consideration that the anode
system can be laid in a particularly simple and rapid manner if the
inflexible titanium ribbons or reticular titanium anodes can be
largely dispensed with, or if the ribbons only need to be laid
linearly. Since the anode system should in any case be laid in a
planar manner, a second material that can be laid in a particularly
simple and flexible manner is used along with the titanium ribbons.
In this case, it was discovered that a linear bundle of a plurality
of carbon fibre filaments, referred to as carbon fibre
multifilament, is sufficiently flexible for planar laying and also
has sufficiently high electrical conductivity to qualify as an
anode system for cathodic corrosion protection. Additionally, a
carbon fibre multifilament of this kind can be obtained in a simple
and cost-effective manner by the yard, allowing significant cost
savings in the construction of an anode system.
[0017] 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 so
as to achieve a particularly uniform distribution and to allow
particularly simple contacting with the primary anode ribbon via
the meanders or the ends of the strips.
[0018] In order to apply the protective current to the planarly
laid bundle, said bundle is electrically connected to a (for
example linearly laid) titanium anode ribbon in a plurality of
contact regions and said primary anode ribbon is connected to a
primary anode wire. As already explained above, said primary anode
wire can be connected to the positive terminal of a voltage
source.
[0019] In addition to using cathodic corrosion protection in steel
constructions (for example port facilities) or piping and
pipelines, it can also be used in the context of reinforced
structures. In this case, the reinforced structures must be
retrofitted with cathodic corrosion protection or this should be
immediately considered for a new construction.
[0020] When restoring reinforced concrete structures, when portions
of the concrete layer are newly applied, and also in the case of
new constructions, in a preferred embodiment the carbon fibre
multifilament is laid on or in the fresh concrete in order to
achieve particularly simple laying. However, in order to prevent
short-circuiting between the carbon fibre multifilament as the
anode and the reinforcement steel as the cathode due to, for
example, the carbon fibre multifilament resting on the
reinforcement steel, a sufficient spacing between the carbon fibre
multifilament and the reinforcement steel is provided by means of
an insulating intermediate layer, for example a glass fibre
composite reinforcement.
[0021] In particular when retrofitting an existing reinforced
structure with cathodic corrosion protection, in an advantageous
embodiment, grooves are cut or milled into the concrete, into which
grooves the carbon fibre multifilament can be laid. Further raising
or enlargement of the concrete layer in order to cover the anode
system is thus avoided.
[0022] In an alternative or additional preferred embodiment, the
carbon fibre multifilament can be adhesively bonded to the concrete
in order to secure it thereto. A conductive adhesive can be used
for this purpose, by means of which the carbon fibre element is
secured to the concrete at individual points or over the entire
region. Said method can be used in particular for restoring old
concrete surfaces. The adhesive used in this case comprises, in a
particularly preferred embodiment, ionic additives and water in
order to itself electrolytically conduct.
[0023] In order to achieve particularly good contact between the
carbon fibre multifilament and the primary anode ribbon, in a
particularly advantageous embodiment the carbon fibre multifilament
is wound around the primary anode ribbon in the contact regions.
This produces a plurality of contact points in these regions, via
which contact points the current from the primary anode ribbon can
be transferred to the carbon fibre multifilament.
[0024] In order to protect the contact regions as effectively as
possible and at the same time better electrically interconnect the
carbon fibre multifilament and the primary anode ribbon, in a
preferred embodiment the contact regions are encased in epoxy
resin. On account of the shrinkage of the epoxy resin after
application, the contact between the carbon fibre multifilament and
the primary anode ribbon is improved even further. The shrinkage of
the epoxy resin is thus used in a targeted manner to enhance the
contact between the carbon fibre multifilament and the primary
anode ribbon. In the case of a metal primary anode, the anode is
preferably insulated such that it does not itself function as a
current-supplying anode. By means of the insulation, the current is
prevented from being fed directly into the electrolyte and too
little thereof ending up in the actual anode. In a preferred
embodiment, the epoxy resin used is therefore not conductive, i.e.
it is insulating.
[0025] Overall, connecting a carbon anode to a primary anode and
the following copper cabling have so far been very difficult to
implement and have represented a big problem. In contrast to other
anode materials, carbon cannot be welded or soldered to the primary
anode or to the copper cabling. However, by using linear and
flexible bundles of carbon fibres, it is possible to wind the
primary anode ribbon in order to increase the contact surface area.
Additionally, there is the possibility of mechanical connection or
adhesive bonding using a conductive adhesive.
[0026] In order to secure the entire anode system, or merely
portions thereof, to the reinforced concrete, said anode system is
advantageously covered with a conductive mortar. As a result, it is
optimally protected against external influences.
[0027] In addition to using cathodic corrosion protection of this
kind in reinforced concrete structures, it is also possible to
protect steel structures, such as piping and port facilities, from
corrosion.
[0028] The advantages achieved by this invention consist in
particular in allowing a particularly simple and cost-effective
planar application of an anode system by using a carbon fibre
multifilament. Use of a fabric that is less flexible during laying
or of a mat as the anode system can therefore be avoided. The
current is thereby fed through linearly laid primary anodes, for
example made of titanium ribbon, and then via the contact regions
into the carbon fibre multifilament and thus is planarly
distributed.
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
* * * * *