CA2316983C - Connector for use in cathodic protection and method of use - Google Patents
Connector for use in cathodic protection and method of use Download PDFInfo
- Publication number
- CA2316983C CA2316983C CA002316983A CA2316983A CA2316983C CA 2316983 C CA2316983 C CA 2316983C CA 002316983 A CA002316983 A CA 002316983A CA 2316983 A CA2316983 A CA 2316983A CA 2316983 C CA2316983 C CA 2316983C
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- Prior art keywords
- anode
- assembly
- connector
- around
- steel
- Prior art date
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- 238000004210 cathodic protection Methods 0.000 title claims abstract description 9
- 238000000034 method Methods 0.000 title claims description 17
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 30
- 239000010959 steel Substances 0.000 claims abstract description 30
- 230000002787 reinforcement Effects 0.000 claims abstract description 21
- 229910052751 metal Inorganic materials 0.000 claims abstract description 19
- 239000002184 metal Substances 0.000 claims abstract description 19
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 10
- 239000011150 reinforced concrete Substances 0.000 claims abstract description 9
- 239000004570 mortar (masonry) Substances 0.000 claims description 17
- 239000011148 porous material Substances 0.000 claims description 12
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 11
- 229910052725 zinc Inorganic materials 0.000 claims description 11
- 239000011701 zinc Substances 0.000 claims description 11
- 239000008151 electrolyte solution Substances 0.000 claims description 10
- 238000005266 casting Methods 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 5
- 239000004567 concrete Substances 0.000 claims description 5
- 238000005260 corrosion Methods 0.000 claims description 5
- 230000007797 corrosion Effects 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 238000004804 winding Methods 0.000 claims description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 3
- 229910001338 liquidmetal Inorganic materials 0.000 claims description 3
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- 239000010405 anode material Substances 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000002844 melting Methods 0.000 claims 1
- 230000008018 melting Effects 0.000 claims 1
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000003513 alkali Substances 0.000 description 6
- 238000010079 rubber tapping Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- ZPUCINDJVBIVPJ-LJISPDSOSA-N cocaine Chemical compound O([C@H]1C[C@@H]2CC[C@@H](N2C)[C@H]1C(=O)OC)C(=O)C1=CC=CC=C1 ZPUCINDJVBIVPJ-LJISPDSOSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 101100194706 Mus musculus Arhgap32 gene Proteins 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 235000002595 Solanum tuberosum Nutrition 0.000 description 1
- 244000061456 Solanum tuberosum Species 0.000 description 1
- 101100194707 Xenopus laevis arhgap32 gene Proteins 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 235000012015 potatoes Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
- C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
- C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
- C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
- C23F13/20—Conducting electric current to electrodes
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
- C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
- C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
- C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
- C23F13/16—Electrodes characterised by the combination of the structure and the material
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F2201/00—Type of materials to be protected by cathodic protection
- C23F2201/02—Concrete, e.g. reinforced
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Prevention Of Electric Corrosion (AREA)
- Non-Disconnectible Joints And Screw-Threaded Joints (AREA)
- Cable Accessories (AREA)
- Processing Of Terminals (AREA)
- Orthopedics, Nursing, And Contraception (AREA)
- Electrotherapy Devices (AREA)
Abstract
An assembly for use in the cathodic protection of steel reinforcement in reinforced concrete said assembly comprises: (i) an anode of a metal having a more negative electrode potential than steel and, in electrical contact therewith, (ii) an elongate electrical connector eg a wire made of a ductile metal capable of being wound around the steel reinforcing element to be protected. The anode may be in the form of a block cast around a portion of the length of the elongate connector and preferably the elongate connector comprises a plurality of wires twisted together over a portion of their length with the anode cast around the twisted portion.
Description
wo oon~9 rc~rics~ro3sm CONNECTOR FOR USE IN CATHODIC
PROTECTION AND METHOD OF USE.
Field of the Invention s This invention relates to the cathodic protection of steel in reinforced concrete employing a sacrificial anode, more particularly to an electrical connector for connecting the sacr~cial anode to the reinforcing steel it is intended to protect and to a method for the installation of the anode.
to Background of the Invention Sacrificial anodes are well known. To be effective the sacrificial anode is made of a metal which has a more negative electrode potential than the steel to be protected so that it will corrode in preference to the steel. Sacrificial anodes are described in European Patent No 0707667 and United States Patent No 5292411.
is Problem to be solved by the Invention To fulfil its purpose the sacrificial anode needs to be connected electrically to the steel to be protected. Metal conductors have been previously used for this purpose. Previously these metal conductors such as wires, have been attached to 2o the steel reinforcement by drilling a hole into which a self tapping screw is inserted. Alternative methods have involved the use of clips or clamps to secure the wire to the metal to be protected.
These methods have problems in that the drifting of holes and use of self tapping 2s screws is time consuming and there is always a risk that the clips and clamps may be dislodged.
The present invention provides a solution to these problems by the use of a ductile elongate connector that is connected to the steel reinforcing element by 3o winding the connector around the reinforcing element..
wo oons~9 rcrics~ro3s~ ~
PROTECTION AND METHOD OF USE.
Field of the Invention s This invention relates to the cathodic protection of steel in reinforced concrete employing a sacrificial anode, more particularly to an electrical connector for connecting the sacr~cial anode to the reinforcing steel it is intended to protect and to a method for the installation of the anode.
to Background of the Invention Sacrificial anodes are well known. To be effective the sacrificial anode is made of a metal which has a more negative electrode potential than the steel to be protected so that it will corrode in preference to the steel. Sacrificial anodes are described in European Patent No 0707667 and United States Patent No 5292411.
is Problem to be solved by the Invention To fulfil its purpose the sacrificial anode needs to be connected electrically to the steel to be protected. Metal conductors have been previously used for this purpose. Previously these metal conductors such as wires, have been attached to 2o the steel reinforcement by drilling a hole into which a self tapping screw is inserted. Alternative methods have involved the use of clips or clamps to secure the wire to the metal to be protected.
These methods have problems in that the drifting of holes and use of self tapping 2s screws is time consuming and there is always a risk that the clips and clamps may be dislodged.
The present invention provides a solution to these problems by the use of a ductile elongate connector that is connected to the steel reinforcing element by 3o winding the connector around the reinforcing element..
wo oons~9 rcrics~ro3s~ ~
Summary of the Invention According to the present invention there is provided an assembly for use in the catholic protection of steel reinforcement in reinforced concrete said assembly comprising:
s (i) an anode of a metal having a more negative electrode potential than steel and, in electrical contact therewith, (ii) an elongate electrical connector made of a ductile metal capable of being wound around the steel reinforcing element to be protected.
to Advantageous Effect of the Invention The connector can be installed in less time than the previously used methods involving the use of self tapping screws and is more secure than the clips or clamps:
~s Brief Description of the Drawings Fig 1 is a perspective view of one embodiment of the invention in which two wires are twisted together Fig 2 is a perspective view on a smaller scale than Fig 1 in which the anode has been cast around the wires of the connector and 20~ Fig 3 is a perspective view on the same scale as Fig 2 of another embodiment in which the anode is surrounded by a mortar which been cast around it.
Detail~d Description of the Invention.
The anode is preferably zinc but aluminium, cadmium or magnesium may be 2s used. References to these metals include alloys containing them.
The electrical contact between the connector and the anode is preferably provided by having the anode in the form of a block which has been cast (by cast we mean allowing the liquid metal to solidify to form the block) around a portion of the length 30 of the elongate connector. Alternatively the electrical contact may provided by the elongate connector being wound around the anode or by the connector being soldered or similarly attached to the anode.
The elongate connector is conveniently in the form of a wire, although other elongate forms may be used. The wire may conveniently be of steel, preferably a 3s mild steel.
Preferably the wire is as noble or more noble than the steel of the reinforcement.
wo oon~9 rcricB~ro3si ~
s (i) an anode of a metal having a more negative electrode potential than steel and, in electrical contact therewith, (ii) an elongate electrical connector made of a ductile metal capable of being wound around the steel reinforcing element to be protected.
to Advantageous Effect of the Invention The connector can be installed in less time than the previously used methods involving the use of self tapping screws and is more secure than the clips or clamps:
~s Brief Description of the Drawings Fig 1 is a perspective view of one embodiment of the invention in which two wires are twisted together Fig 2 is a perspective view on a smaller scale than Fig 1 in which the anode has been cast around the wires of the connector and 20~ Fig 3 is a perspective view on the same scale as Fig 2 of another embodiment in which the anode is surrounded by a mortar which been cast around it.
Detail~d Description of the Invention.
The anode is preferably zinc but aluminium, cadmium or magnesium may be 2s used. References to these metals include alloys containing them.
The electrical contact between the connector and the anode is preferably provided by having the anode in the form of a block which has been cast (by cast we mean allowing the liquid metal to solidify to form the block) around a portion of the length 30 of the elongate connector. Alternatively the electrical contact may provided by the elongate connector being wound around the anode or by the connector being soldered or similarly attached to the anode.
The elongate connector is conveniently in the form of a wire, although other elongate forms may be used. The wire may conveniently be of steel, preferably a 3s mild steel.
Preferably the wire is as noble or more noble than the steel of the reinforcement.
wo oon~9 rcricB~ro3si ~
The connector may comprise a plurality of wires twisted together over a portion of their length and the anode may be cast around the twisted portion. By the word twisted we mean to include folded or bent or crimped. The purpose of the twisted portion is to increase the surface area of the wire forming the interface with the s cast anode and thereby improve the electrical contact. The wires may be twisted together at a position which is intermediate their ends (for example near the middle of their lengths) so that lengths of wire extend on both sides of the cast anode.
io Patent Application No WO 94/29496 (European Patent Application No 0707667) describes a method of cathodic protection in which to maintain the cathodic protection over a sustained period of time the anode is surrounded by a material containing an electrolyte of high pH. To avoid passivation of the anode it recommends that in the case of a zinc anode the pH is at least about 14.
~s Suitable materials described in this patent are cementitious mortars which may be cast around the anode to form a unit. It is not essential that the mortar is cementitious although such mortars are more readily available. The mortar may be prepared from a cement that has an intrinsically high alkali content or additions!
2o alkali may be added to the mortar eg sodium hydroxide or lithium hydroxide, the latter being preferred.
The assembly of anode and - connector of the present invention may have a porous material eg a cementitious mortar cast around the anode. By cast we 2s mean forming a solid block from the liquid or semiliquid mortar. The casting is preferably carried out in a mold. The porous material is one that preferably contains a high pH electrolyte as described in European Patent Application No 0707667 ie one containing an electrolyte solution whose pH is sufficiently high to maintain corrosion of the anode and passive film formation on the anode to be 3o avoided when the anode is galvanically connected to the steel reinforcement. In the case of a cementitious mortar the electrolyte solution is the pore solution.
The mortar will preferably.have a content of alkali equivalent to at least 1 %
lithium hydroxide based on the dry weight of the ingredients used to make the mortar.
An 3s equivalent amount of sodium hydroxide is 2% by weight. Conveniently the amount of lithium hydroxide is greater than 2% or an equivalent amount of sodium hydroxide of 4%.
wo eons~9 rcrics~ro3sm Lithium hydroxide is the preferred alkali because lithium ions provide protection against alkali silica (or alkali aggregate) reactions in concrete. However mixtures of alkalis may be used for example mixtures of lithium hydroxide and sodium hydroxide.
s The anode, the porous material eg mortar and the casting may also be as described in European Patent Application No 0707667.
~o According to another aspect of the present invention there is provided a method of installing a sacrificial anode to protect the reinforcement of reinforced concrete which method comprises the following steps (a) and (b) in any order (a) making an electrical connection between an elongate connector and the anode i s and (b) making electrical contact with the steel reinforcement by winding the elongate connector around the steel reinforcement.
The step (a) may comprise casting the anode around a portion of the length of the 2o elongate connector.
A further step (c) may be carried out before or after step (b) which step (c) comprises casting around the anode a porous material containing an electrolyte solution having a pH suffcciently high for corrosion of the anode to occur and 2s passive film formation to be avoided.
Preferably the anode is zinc in which case the pH of the electrolyte solution is desirably at least about 14. When the anode is of another metal such as aluminium the pH may be lower, for example at least 13.3 or 13.5 3o The pH may be determined by measuring the hydroxyl ion concentration and applying the equation pH = 14 + log (OH-) after Sorensen.
The invention is applicable to the construction of new reinforced concrete 3s structures in which the anode assembly is connected to the reinforcement by means of the connector and a high pH porous material such as a mortar cast around the anode.
The invention is also applicable to the protection of existing concrete structures in which method a hole may be made in the concrete and (l) the anode inserted into the hole and (ii) the connector connected to the reinforcement and (iii) the high pH material cast around the anode. Steps (l), (ii) and (iii) may be carried out in any 3 order Referring to 1=ig 1 of the drawings two wires each being a 18 8WG (standard wire guage) mild steel wire are twisted together over part of their length at 6_ The length Of the twisted portion 6 is typically from about 38 to 42 mm. Four lengths of vo uvire in the form of arms 2, 4. 8 and 'I0 extend from the twisted portion 6. The length of the arcns 2, 4. 8 and I o is typically from about 148 to 152mm and at the end of each arm are loops 12, 13 'i4 and 5. The arms are each wound around the reinforaetllent. Usually one or two complete winds around the reinforcement is sufficient to make a satisfactory electrical contact. The diameter of the Poops is l s typically from about 9 to 1 t mm. The purpose of the loops is to facilitate the use of a toot of the type used to close paper sacks for potatoes and the tike. A
suitable too! iS a spring loaded watchet twisting tool known as the Stanley tying tool and is available from Direct Wtre Ties Limited. 8y means of the toot the arms which have been wound around the steel reinforcement (not shown) in reinforced concrete 2o may then be twisted together. This has the effect of tightening the wire around the reinforcement.
In Fig z a cylindrical zinc block 2t) of about 40 mm diameter and about 7mm thleKness has been cast around the twisted wires. tn the Figure the centre of the ~s cylindrical biook 20 has been omitted to show the wires. The top and bottom edges of the btOdc 20 have been rounded to prevent crack inducement.
The assembly shown in Fig 2 was made by first twisting the wires together neat the middle of their length and placing the twisted portion in a ceramic casting 30 mould. Molten zinc was then poured into the mould. After solidifying the product which was recroved from the mould. The wire arms 2, 4 8, and 1U extend on both sides of the anode and enable the anode to be connected to more than one reinforcing element if desired.
as !n Fig 3 a block of mortar 2~ has been cast around the zinc shown in Fig 2 to give a thickness of 10 mm all round the zinc.
wo oor~r~9 Pc~ricB~ro3sm The assembly shown in Fig 3 was made by positioning the assembly shown in Fig 2 in a previously vacuum formed plastic mould so as to locate the zinc centrally in the mould. A high pH cementitious mortar containing a pore solution of pH
greater than 14 was prepared by mixing a Portland cement powder (containing 2% by s weight of added lithium hydroxide based on the weight of the cement powder) with water and poured into the mould. This was allowed to harden for four hours and then removed from the mould to yield the product shown in Fig 3.
io Patent Application No WO 94/29496 (European Patent Application No 0707667) describes a method of cathodic protection in which to maintain the cathodic protection over a sustained period of time the anode is surrounded by a material containing an electrolyte of high pH. To avoid passivation of the anode it recommends that in the case of a zinc anode the pH is at least about 14.
~s Suitable materials described in this patent are cementitious mortars which may be cast around the anode to form a unit. It is not essential that the mortar is cementitious although such mortars are more readily available. The mortar may be prepared from a cement that has an intrinsically high alkali content or additions!
2o alkali may be added to the mortar eg sodium hydroxide or lithium hydroxide, the latter being preferred.
The assembly of anode and - connector of the present invention may have a porous material eg a cementitious mortar cast around the anode. By cast we 2s mean forming a solid block from the liquid or semiliquid mortar. The casting is preferably carried out in a mold. The porous material is one that preferably contains a high pH electrolyte as described in European Patent Application No 0707667 ie one containing an electrolyte solution whose pH is sufficiently high to maintain corrosion of the anode and passive film formation on the anode to be 3o avoided when the anode is galvanically connected to the steel reinforcement. In the case of a cementitious mortar the electrolyte solution is the pore solution.
The mortar will preferably.have a content of alkali equivalent to at least 1 %
lithium hydroxide based on the dry weight of the ingredients used to make the mortar.
An 3s equivalent amount of sodium hydroxide is 2% by weight. Conveniently the amount of lithium hydroxide is greater than 2% or an equivalent amount of sodium hydroxide of 4%.
wo eons~9 rcrics~ro3sm Lithium hydroxide is the preferred alkali because lithium ions provide protection against alkali silica (or alkali aggregate) reactions in concrete. However mixtures of alkalis may be used for example mixtures of lithium hydroxide and sodium hydroxide.
s The anode, the porous material eg mortar and the casting may also be as described in European Patent Application No 0707667.
~o According to another aspect of the present invention there is provided a method of installing a sacrificial anode to protect the reinforcement of reinforced concrete which method comprises the following steps (a) and (b) in any order (a) making an electrical connection between an elongate connector and the anode i s and (b) making electrical contact with the steel reinforcement by winding the elongate connector around the steel reinforcement.
The step (a) may comprise casting the anode around a portion of the length of the 2o elongate connector.
A further step (c) may be carried out before or after step (b) which step (c) comprises casting around the anode a porous material containing an electrolyte solution having a pH suffcciently high for corrosion of the anode to occur and 2s passive film formation to be avoided.
Preferably the anode is zinc in which case the pH of the electrolyte solution is desirably at least about 14. When the anode is of another metal such as aluminium the pH may be lower, for example at least 13.3 or 13.5 3o The pH may be determined by measuring the hydroxyl ion concentration and applying the equation pH = 14 + log (OH-) after Sorensen.
The invention is applicable to the construction of new reinforced concrete 3s structures in which the anode assembly is connected to the reinforcement by means of the connector and a high pH porous material such as a mortar cast around the anode.
The invention is also applicable to the protection of existing concrete structures in which method a hole may be made in the concrete and (l) the anode inserted into the hole and (ii) the connector connected to the reinforcement and (iii) the high pH material cast around the anode. Steps (l), (ii) and (iii) may be carried out in any 3 order Referring to 1=ig 1 of the drawings two wires each being a 18 8WG (standard wire guage) mild steel wire are twisted together over part of their length at 6_ The length Of the twisted portion 6 is typically from about 38 to 42 mm. Four lengths of vo uvire in the form of arms 2, 4. 8 and 'I0 extend from the twisted portion 6. The length of the arcns 2, 4. 8 and I o is typically from about 148 to 152mm and at the end of each arm are loops 12, 13 'i4 and 5. The arms are each wound around the reinforaetllent. Usually one or two complete winds around the reinforcement is sufficient to make a satisfactory electrical contact. The diameter of the Poops is l s typically from about 9 to 1 t mm. The purpose of the loops is to facilitate the use of a toot of the type used to close paper sacks for potatoes and the tike. A
suitable too! iS a spring loaded watchet twisting tool known as the Stanley tying tool and is available from Direct Wtre Ties Limited. 8y means of the toot the arms which have been wound around the steel reinforcement (not shown) in reinforced concrete 2o may then be twisted together. This has the effect of tightening the wire around the reinforcement.
In Fig z a cylindrical zinc block 2t) of about 40 mm diameter and about 7mm thleKness has been cast around the twisted wires. tn the Figure the centre of the ~s cylindrical biook 20 has been omitted to show the wires. The top and bottom edges of the btOdc 20 have been rounded to prevent crack inducement.
The assembly shown in Fig 2 was made by first twisting the wires together neat the middle of their length and placing the twisted portion in a ceramic casting 30 mould. Molten zinc was then poured into the mould. After solidifying the product which was recroved from the mould. The wire arms 2, 4 8, and 1U extend on both sides of the anode and enable the anode to be connected to more than one reinforcing element if desired.
as !n Fig 3 a block of mortar 2~ has been cast around the zinc shown in Fig 2 to give a thickness of 10 mm all round the zinc.
wo oor~r~9 Pc~ricB~ro3sm The assembly shown in Fig 3 was made by positioning the assembly shown in Fig 2 in a previously vacuum formed plastic mould so as to locate the zinc centrally in the mould. A high pH cementitious mortar containing a pore solution of pH
greater than 14 was prepared by mixing a Portland cement powder (containing 2% by s weight of added lithium hydroxide based on the weight of the cement powder) with water and poured into the mould. This was allowed to harden for four hours and then removed from the mould to yield the product shown in Fig 3.
Claims (18)
1. An assembly for use in the cathodic protection of steel reinforcement in reinforced concrete said assembly comprising:
(i) an anode of a metal having a more negative electrode potential than steel;
and (ii) an elongated electrical connector physically and electrically connected to said anode and made of a ductile metal; and wherein said anode is in the form of a block formed around a portion of the length of said elongated connector.
(i) an anode of a metal having a more negative electrode potential than steel;
and (ii) an elongated electrical connector physically and electrically connected to said anode and made of a ductile metal; and wherein said anode is in the form of a block formed around a portion of the length of said elongated connector.
2. An assembly as claimed in claim 1 wherein said elongated connector is in the form of at least one wire.
3. An assembly as claimed in claim 1 wherein said elongated connector comprises a plurality of wires twisted together over a portion of their length, and wherein said anode has been formed around said twisted portion.
4. An assembly as claimed in claim 3 wherein said wires are twisted together at a position intermediate their ends so that said wires extend outwardly from more than one side of said anode.
5. An assembly as claimed in claim 1 wherein said anode is enclosed in a porous material which has been cast around said anode, said porous material containing an electrolyte solution whose pH is sufficiently high for corrosion of said anode to occur and passive film formation on said anode to be avoided when the anode is galvanically connected to a concrete steel reinforcement.
6. An assembly as claimed in claim 5 wherein said anode is made of zinc and said porous material is a cementitious mortar containing an electrolyte solution of pH
at least about 14.
at least about 14.
7. An assembly as claimed in claim 1 in combination with a concrete steel reinforcing element; and wherein said assembly is connected to said reinforcing element by winding said elongated connector around said reinforcing element.
8. An assembly as claimed in claim 7 wherein said elongated connector comprises at least one wire of a material as noble or more noble than the steel of said steel reinforcing element.
9. An assembly as recited in claim 8 wherein said elongated connector comprises a plurality of wires twisted together over a portion of their length, and wherein said anode has been formed around said twisted portion.
10. An assembly as claimed in claim 9 wherein said wires are twisted together at a position intermediate their ends so that said wires extend outwardly from more than one side of said anode.
11. An assembly for use in the cathodic protection of concrete-reinforcing steel reinforcing elements, said assembly comprising:
at least first and second wires twisted together at a position intermediate their ends to form a twisted portion;
a block of anode material cast around said twisted portion, so that at least four wire arms extend outwardly from said block; and wherein said wires are of ductile metal.
at least first and second wires twisted together at a position intermediate their ends to form a twisted portion;
a block of anode material cast around said twisted portion, so that at least four wire arms extend outwardly from said block; and wherein said wires are of ductile metal.
12. An assembly as recited in claim 11 wherein said anode is made of zinc, and wherein said wires are mild steel, and wherein said anode is enclosed in a porous cementitious mortar containing an electrolyte solution of a pH at least about 14.
13. A method of making an assembly for use in the cathodic protection of steel reinforcement in reinforced concrete using an anode of a metal having a more negative electrode potential than steel, and an elongated electrical connector made of a ductile metal, said method comprising:
(a) melting the metal for the anode, so that it is in liquid form;
(b) placing a part of the length of the connector in a mold; and (c) casting the anode from the liquid metal in the mold to form a block of metal around a portion of the length of the elongated electrical connector.
(a) melting the metal for the anode, so that it is in liquid form;
(b) placing a part of the length of the connector in a mold; and (c) casting the anode from the liquid metal in the mold to form a block of metal around a portion of the length of the elongated electrical connector.
14. A method as claimed in claim 13 further comprising (d) producing a liquid or semi-liquid mixture of a porous material containing an electrolyte solution having a pH sufficiently high for corrosion of the anode to occur and passive film formation on the anode to be avoided when connected to a steel reinforcement; and (e) forming a solid block of the mixture around the anode from (c).
15. A method of installing a sacrificial anode to protect the steel reinforcement of reinforced concrete which method comprises in any order:
(a) making an electrical connection between the sacrificial anode and an elongated connector made of a ductile metal;
(b) making electrical contact between the elongated connector and the steel reinforcement by winding the elongated connector around the steel reinforcement;
and after (b) (c) tightening the electrical connector around the reinforcement by twisting the ends of the elongated connector together using a twisting tool.
(a) making an electrical connection between the sacrificial anode and an elongated connector made of a ductile metal;
(b) making electrical contact between the elongated connector and the steel reinforcement by winding the elongated connector around the steel reinforcement;
and after (b) (c) tightening the electrical connector around the reinforcement by twisting the ends of the elongated connector together using a twisting tool.
16. A method as claimed in claim 15 wherein (a) is practiced by casting the anode from a liquid metal in a mold containing part of the connector to form a block of metal around a portion of the length of the elongated connector.
17. A method as claimed in claim 16 further comprising, carried out before or after (b), (c) casting around the anode a porous material containing an electrolyte solution having a pH sufficiently high for corrosion of the anode to occur and passive film formation to be avoided.
18. A method as claimed in claim 17 wherein (a)-(c) are practiced using a zinc anode and using an electrolyte solution having a pH of at least about 14.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9823654.0 | 1998-10-29 | ||
| GBGB9823654.0A GB9823654D0 (en) | 1998-10-29 | 1998-10-29 | Connector for use in cathodic protection and method of use |
| US09/306,419 US6193857B1 (en) | 1998-10-29 | 1999-05-06 | Connector for use in cathodic protection and method of use |
| US09/306,419 | 1999-05-06 | ||
| PCT/GB1999/003517 WO2000026439A2 (en) | 1998-10-29 | 1999-10-28 | Connector for use in cathodic protection and method of use |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2316983A1 CA2316983A1 (en) | 2000-05-11 |
| CA2316983C true CA2316983C (en) | 2007-01-09 |
Family
ID=26314583
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002316983A Expired - Fee Related CA2316983C (en) | 1998-10-29 | 1999-10-28 | Connector for use in cathodic protection and method of use |
Country Status (18)
| Country | Link |
|---|---|
| EP (1) | EP1042535B1 (en) |
| JP (1) | JP4491139B2 (en) |
| CN (1) | CN1195897C (en) |
| AT (1) | ATE310110T1 (en) |
| AU (1) | AU752647B2 (en) |
| BR (1) | BR9907086B1 (en) |
| CA (1) | CA2316983C (en) |
| CZ (1) | CZ295912B6 (en) |
| DE (1) | DE69928373T2 (en) |
| ES (1) | ES2253931T3 (en) |
| HK (1) | HK1049503B (en) |
| ID (1) | ID26715A (en) |
| NO (1) | NO323184B1 (en) |
| NZ (1) | NZ505421A (en) |
| PL (1) | PL195262B1 (en) |
| TR (1) | TR200002510T1 (en) |
| TW (1) | TW581826B (en) |
| WO (1) | WO2000026439A2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10227698B2 (en) | 2012-07-30 | 2019-03-12 | Construction Research & Technology Gmbh | Galvanic anode and method of corrosion protection |
| US12188133B2 (en) | 2022-01-20 | 2025-01-07 | Bradley Anthony SIMPSON | Cable-to-pipe connector |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2425778B8 (en) | 2004-07-06 | 2019-05-01 | E Chem Tech Ltd | Protection of reinforcing steel |
| WO2006097770A2 (en) | 2005-03-16 | 2006-09-21 | Gareth Glass | Treatment process for concrete |
| JP2006336072A (en) * | 2005-06-02 | 2006-12-14 | Tokyo Electric Power Co Inc:The | Simple anti-corrosion equipment |
| AU2006348127B2 (en) * | 2006-09-11 | 2012-05-31 | Vsl International Ag | Method and sensor for determining the passivating properties of a mixture containing at least two components, which are cement and water |
| JP4772642B2 (en) * | 2006-10-20 | 2011-09-14 | 電気化学工業株式会社 | Electrochemical treatment of concrete floor slabs on asphalt paved roads |
| CN104532259B (en) * | 2014-12-26 | 2017-10-20 | 青岛双瑞海洋环境工程股份有限公司 | The composite electrochemical device protected for condenser pipe series cathode |
| CN110467378B (en) * | 2019-08-05 | 2021-11-09 | 西安建筑科技大学 | Concrete with structure and corrosion control function integrated |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3434222A1 (en) * | 1984-09-18 | 1986-03-20 | Roth, Manfred, Dipl.-Volksw., 3563 Dautphetal | Corrosion protection device for fuel oil tanks made of sheet steel |
| DE3826926A1 (en) * | 1988-08-09 | 1990-02-15 | Heraeus Elektroden | ANODE FOR CATHODIC CORROSION PROTECTION |
| GB9312431D0 (en) * | 1993-06-16 | 1993-07-28 | Aston Material Services Ltd | Improvements in and relating to protecting reinforced concrete |
-
1999
- 1999-10-28 PL PL99348189A patent/PL195262B1/en not_active IP Right Cessation
- 1999-10-28 WO PCT/GB1999/003517 patent/WO2000026439A2/en active IP Right Grant
- 1999-10-28 ES ES99971473T patent/ES2253931T3/en not_active Expired - Lifetime
- 1999-10-28 ID IDW20001266A patent/ID26715A/en unknown
- 1999-10-28 HK HK03101631.0A patent/HK1049503B/en not_active IP Right Cessation
- 1999-10-28 BR BRPI9907086-3A patent/BR9907086B1/en not_active IP Right Cessation
- 1999-10-28 DE DE69928373T patent/DE69928373T2/en not_active Expired - Lifetime
- 1999-10-28 CN CNB998034355A patent/CN1195897C/en not_active Expired - Fee Related
- 1999-10-28 JP JP2000579806A patent/JP4491139B2/en not_active Expired - Fee Related
- 1999-10-28 CA CA002316983A patent/CA2316983C/en not_active Expired - Fee Related
- 1999-10-28 EP EP99971473A patent/EP1042535B1/en not_active Expired - Lifetime
- 1999-10-28 TW TW088118633A patent/TW581826B/en not_active IP Right Cessation
- 1999-10-28 TR TR2000/02510T patent/TR200002510T1/en unknown
- 1999-10-28 CZ CZ20002437A patent/CZ295912B6/en not_active IP Right Cessation
- 1999-10-28 AU AU13938/00A patent/AU752647B2/en not_active Expired
- 1999-10-28 NZ NZ505421A patent/NZ505421A/en not_active IP Right Cessation
- 1999-10-28 AT AT99971473T patent/ATE310110T1/en not_active IP Right Cessation
-
2000
- 2000-06-28 NO NO20003386A patent/NO323184B1/en not_active IP Right Cessation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10227698B2 (en) | 2012-07-30 | 2019-03-12 | Construction Research & Technology Gmbh | Galvanic anode and method of corrosion protection |
| US12188133B2 (en) | 2022-01-20 | 2025-01-07 | Bradley Anthony SIMPSON | Cable-to-pipe connector |
Also Published As
| Publication number | Publication date |
|---|---|
| PL195262B1 (en) | 2007-08-31 |
| CZ20002437A3 (en) | 2001-07-11 |
| JP2002528647A (en) | 2002-09-03 |
| EP1042535A1 (en) | 2000-10-11 |
| WO2000026439A3 (en) | 2000-10-19 |
| NO20003386L (en) | 2000-08-24 |
| BR9907086B1 (en) | 2009-08-11 |
| JP4491139B2 (en) | 2010-06-30 |
| PL348189A1 (en) | 2002-05-06 |
| CN1195897C (en) | 2005-04-06 |
| AU1393800A (en) | 2000-05-22 |
| ATE310110T1 (en) | 2005-12-15 |
| CZ295912B6 (en) | 2005-11-16 |
| TR200002510T1 (en) | 2001-04-20 |
| HK1049503B (en) | 2005-11-18 |
| WO2000026439A2 (en) | 2000-05-11 |
| HK1049503A1 (en) | 2003-05-16 |
| DE69928373D1 (en) | 2005-12-22 |
| BR9907086A (en) | 2000-10-17 |
| NO323184B1 (en) | 2007-01-15 |
| CA2316983A1 (en) | 2000-05-11 |
| TW581826B (en) | 2004-04-01 |
| AU752647B2 (en) | 2002-09-26 |
| NZ505421A (en) | 2002-11-26 |
| EP1042535B1 (en) | 2005-11-16 |
| DE69928373T2 (en) | 2006-08-03 |
| ES2253931T3 (en) | 2006-06-01 |
| CN1376213A (en) | 2002-10-23 |
| ID26715A (en) | 2001-02-01 |
| NO20003386D0 (en) | 2000-06-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20191028 |