Method and apparatus for cathodic protection of reinforcing steel in a concrete structure located in an ionically conductive liquid

Abstract

Cathodic protection of rebar in concrete columns in seawater is simplified by providing a pre-assembled unit that includes a jacket surrounding the column, carrying a bulk sacrificial anode on the exterior of the jacket and an inner sacrificial anode with optional grout poured inside the jacket. The jacket can also include a pre-assembled connection box and couplings for connecting to the rebar. The jacket is attached to the surface of the column at the water line so that the bulk anode is located below the water level. The bulk anode can be made of aluminum for low toxicity in seawater. An activator is applied to the inside of the jacket as a wicking layer or chemically active material. The jacket can function solely as a formwork that is removed after the grout is poured.

Description

[Technical Field]

[0001] The present invention relates to a method for cathodic protection of reinforcing steel bars within concrete structures that are partly in contact with and partly above the wetting medium, such as pillars and piles in a saltwater environment. [Background technology]

[0002] Concrete structures such as pillars in saltwater tend to corrode above the saltwater in the intertidal zone where the pillars wet and dry, and in and above the splash zone where the concrete is occasionally exposed to saltwater.

[0003] One solution to this problem is to surround the column with a jacket containing a layer of grout, inside which sacrificial anodes, such as mesh, sheets, or strips, are buried or placed. This anode is electrically connected to the rebar in the column, and current flows through the connections, allowing ionic current to flow from the anode to the rebar through the electrolyte and concrete, tending to inhibit corrosion of the rebar in favor of corrosion of the sacrificial anode.

[0004] An example of this type of configuration is shown in commonly assigned U.S. Patent No. 9,447,506, issued September 20, 2016, and U.S. Patent No. 7,520,974, issued April 21, 2009. Further examples are shown in prior U.S. Patent No. 5,714,045 (Lasa), issued February 3, 1998, and U.S. Patent No. 4,692,066 (Clear), issued September 8, 1987, both of which are assigned to Alltrista Corporation.

[0005] For further details, reference can be made to the disclosures of the above-mentioned documents.

[0006] It is known that simply fastening an anode to a pillar below the water line will protect the submerged portion of the pillar. Because saltwater is highly conductive, most of the current generated is transferred to the rebar in the wetted portion of the pillar, and little of the current generated by galvanic action is transferred to the highly corroded areas at and above the wetted and dried water line. This issue is discussed in the above-referenced Clear patent.

[0007] In some cases, such as that shown in Lasa, supra, the above jacket and anode configuration is used in conjunction with an additional anode below the water surface, commonly known as a bulk anode, to prevent the lower portion of the mesh anode within the jacket, which is largely or entirely below the water surface, from corroding and being lost rapidly.

[0008] In other cases, a simple, inexpensive repair without cathodic protection involves a simple wrapping around the column at the waterline to mask the worst of the damage. While this configuration may provide a physical barrier, it does not, of course, provide cathodic protection through galvanic action, allowing corrosion of the underlying layers to progress. As discussed by Lasa above, this type of repair is considered merely cosmetic, masking the worst of the cracks and exposed rebar. However, this can result in an inexpensive repair with a short lifespan of protection. The wrapping can surround a layer of grout that covers the worst of the cracks and repairs holes, or the wrapping can be applied directly to the column. In some cases, it is filled with a non-cementitious material such as epoxy resin. Summary of the Invention

[0009] It is an object of the present invention to provide an apparatus or method for the cathodic protection of pillars, for example in seawater, where the applied structure can be easily and simply applied to the pillars and provides effective protection of both the rebar below the water line and the rebar at and above the water line in the wetted zone.

[0010] According to the present invention, there is provided a method for cathodic protection of reinforcing steel within a concrete structure located in an ionically conductive medium, wherein a first portion of the concrete structure is below the surface of the medium and in contact with the medium, a second portion of the concrete structure contiguous with the first portion is above the surface of the medium, and the concrete structure has reinforcing steel in both the first and second portions, the method comprising: providing a coating layer disposed over at least a portion of at least one exterior surface of the concrete structure, the interior surface of the coating layer being disposed adjacent to the at least one exterior surface; providing a bulk anode made of a sacrificial material for generating a galvanic current in a rebar inside the concrete structure, the bulk anode being positioned outside the coating layer and below the surface of the medium; carrying a bulk anode before being applied to at least a portion of said at least one outer surface of the concrete structure for coating by a coating layer; attaching the coating layer to the concrete structure so as to attach a bulk anode carried by the coating layer to the concrete structure; providing an electrical connection between the bulk anode and the rebar such that an ionic current flows between the bulk anode and the rebar to tend to inhibit corrosion of the rebar; Includes.

[0011] Preferably, an inner anode made of a sacrificial material is provided for generating a galvanic current in the rebar, the inner anode being positioned between the inner surface of the cladding material and the at least one outer surface of the concrete structure.

[0012] In one embodiment, the coating layer supports both the inner anode and the bulk anode, and is attached to the concrete structure before being applied to at least a portion of at least one outer surface of the concrete structure for coating. The inner anode(s) can be installed on the surface of the column, allowing wiring to be connected without the jacket getting in the way. The inner anode(s) can be individual strips or rods, or formed as a mesh or sheet. In some cases, the inner anode can be omitted, and all corrosion protection can be provided by the bulk anode.

[0013] Also in accordance with the present invention, there is provided an apparatus for the cathodic protection of reinforcing steel within a concrete structure located in an ionically conductive aqueous medium, whereby a first portion of the concrete structure is below the surface of the medium and in contact with the medium, a second portion of the concrete structure contiguous with the first portion is above the surface of the medium, the concrete structure having reinforcing steel in both the first and second portions, the apparatus comprising: a coating layer disposed to cover at least a portion of at least one outer surface of the concrete structure, the inner surface of the coating layer being disposed adjacent to the outer surface; an inner anode made of a sacrificial material for generating a galvanic current in the rebar, the inner anode being carried by the coating layer so as to be located between the inner surface of the coating and the outer surface of the concrete structure when the coating is attached to the concrete structure; a bulk anode made of a sacrificial material for generating a galvanic current in a reinforcing steel bar inside the concrete structure, the bulk anode being supported on the coating layer so as to be located outside the coating layer and below the surface of the medium when the coating material is attached to the concrete structure; an electrical connection from the inner anode for connection to rebar inside the concrete structure; an electrical connection from the bulk anode for connection to rebar within the concrete structure; Equipped with The coating layer carries both the inner anode and the bulk anode as a pre-assembled structure before being applied to said at least a portion of at least one outer surface of the concrete structure for coating.

[0014] The covering layer can be formed as a single component that wraps around the surface to be covered. Thus, for example, if the concrete structure forms a column, the covering layer can be formed into a jacket of the required cross section as a single piece, which can be opened along one side, wrapped around the column, and connected to form a complete perimeter jacket. The covering layer can also comprise a plurality of separate panels, in which case the method includes connecting the panels to form an assembly that engages at least two, typically all, faces of the concrete structure or column. For example, the covering layer can be formed in two sections that connect together along the side edges. As another example, the covering layer can be formed from a series of panels. In particular, in another example, the separate panels include a plurality of flat panels and a plurality of corner panels that connect together to engage multiple surfaces of the concrete structure.

[0015] In this configuration formed of different panels, preferably at least one of the panels carries at least a portion of the inner anode on its inner surface and at least one other panel carries a bulk anode on its outer surface. Alternatively, at least one panel carries at least a portion of the inner anode on its inner surface and a bulk anode on its outer surface. In some cases, the inner anode is provided as a separate component or components and is therefore not part of the assembled structure.

[0016] The arrangements herein are particularly suited to arrangements in which the concrete structure comprises columns or piles which may have a rectangular, square or circular cross section, and the covering layer, when installed, forms a jacket which completely surrounds the columns.

[0017] Preferably, the coating layer formed by the one or more coating components comprises the bulk anode and, optionally, the inner anode as a pre-assembled structure that can be transported, supplied, and simply applied to the concrete structure on-site as supplied. Preferably, the pre-assembled structure also includes electrical connections from the inner anode to connect to rebar inside the concrete structure, and electrical connections from the bulk anode to connect to rebar inside the concrete structure (if included), so that it can be pre-assembled, pre-attached, and laid in place inside the coating layer or jacket.

[0018] Preferably the pre-assembled structure also includes an electrical connection box containing connection terminals for connecting to the electrical connections from the bulk anode and optionally the electrical connections from the inner anode and electrical connections, which are preferably attached to the coating layer with connection wires in place and bonded to the connection box, in this way the structure can be easily installed on a concrete structure that has been supplied with the components already in place.

[0019] Preferably, the electrical junction box is mounted within the covering layer and is contained within the grout layer when introduced into the covering layer, but the electrical junction box may also be accessible from outside the covering layer, for example via a removable cover, so that terminals on the junction box can be accessed and disconnected as required, or probes from suitable instruments can be applied to perform current or voltage tests.

[0020] Because bulk anodes typically require 10 to 50 pounds of zinc to provide the long-term corrosion protection required for the entire steel below the waterline, they can be attached to the outside of the coating layer, with a connecting plate on the inside surface of the coating layer connecting the anode and plate with fasteners that penetrate the coating layer. This increases the strength of the coating layer, and the coating layer can be made of extruded plastic material or fiber-reinforced plastic. Connecting plates can be added on both the inside and outside for additional strength and rigidity. Preferably, supports are provided that extend from the bulk anode and / or connecting plate attached to the coating layer into the grout after it has hardened after pouring. This provides better support for the bulk anode.

[0021] Typically, the jacket defines a foam layer spaced from the surface of the concrete structure to define a cavity between the jacket and the surface of the concrete structure that is filled by receiving a grout layer, and therefore the jacket is typically impermeable to reduce water migration and oxygen passage to the rebar in the area under the jacket.

[0022] In a particularly preferred arrangement, the covering layer includes a bottom closure member to prevent leakage of grout from the bottom, so that grout can be filled from the top.

[0023] Preferably, the covering layer supports the bulk anode attached to the covering layer as a pre-assembled unit, so that when the covering layer is attached to the concrete structure, the bulk anode is attached to the concrete structure at a height below the seawater surface. Therefore, when the bulk anode is installed, it is supported relative to the concrete surface solely by its connection to the covering layer. This eliminates the need for a separate attachment of the bulk anode to the concrete structure. Because the bulk anode is typically attached to a below-waterline column using a separate, custom-made attachment, this often requires a diver to make the connection, significantly increasing the difficulty and cost. The bulk anode is supported at the bottom of the below-waterline jacket to provide corrosion protection for the below-waterline rebar despite the high conductivity of seawater.

[0024] The common structure including the covering layer may act as a form for a grout layer that is poured onto the surface of the concrete, or the common structure may be applied directly to the surface of the concrete.

[0025] Preferably, the sacrificial anode comprises an anode sheet, which may be a mesh material or other form of solid or perforated material for covering at least a portion of the concrete structure. Alternatively, the anode may be in the form of one or more separate pieces of suitable shape, such as rods or strips, with the covering layer extending along or surrounding the length of the anode rods or strips.

[0026] Preferably, at least one activator is provided at or adjacent to the sacrificial anode to promote corrosion of the anode. The activator can be of any type well known in the art.

[0027] According to a further aspect of the present invention, there is provided a method of cathodic protecting rebar within a concrete structure located in an ionically conductive medium, wherein a first portion of the concrete structure is below the surface of the medium and in contact with the medium, a second portion of the concrete structure contiguous with the first portion is above the surface of the medium, the concrete structure having rebar in both the first portion and the second portion, the method comprising: providing a coating layer disposed over at least a portion of at least one exterior surface of the concrete structure, the interior surface of the coating layer being disposed adjacent to the at least one exterior surface; providing an inner anode made of a sacrificial material for generating a galvanic current in the rebar, the inner anode being positioned so as to be located between an inner surface of the cladding material and the at least one outer surface of the concrete structure; providing a bulk anode made of a sacrificial material for generating a galvanic current in a rebar inside the concrete structure, the bulk anode being positioned outside the coating layer and below the surface of the medium; attaching the covering layer to the concrete structure; providing electrical connections between the inner anode and the rebar and between the bulk anode and the rebar so that ionic current flows between the inner anode and the bulk anode and the rebar to tend to inhibit corrosion of the rebar; Including, The bulk anode comprises aluminum.

[0028] The inner anode may comprise aluminum or zinc and is encapsulated to contain any toxicity.

[0029] The primary benefit of using aluminum bulk anodes is environmental. While aluminum is lighter than zinc and has a higher current per mole, its primary benefit is its low toxicity to certain marine organisms. Zinc is an essential element and is metabolized by mammals and fish. However, shellfish such as oysters are highly sensitive to zinc in water, which can be toxic to oyster farms, mussels, and other shellfish. For this reason, there is some hesitation in using zinc anodes that are unrestrictedly exposed to water. Zinc anodes embedded in jacket assemblies generally present no concern, as they may contain corrosion products, depending on the specific configuration. Aluminum in water is much less toxic to these organisms.

[0030] Where this specification refers to aluminum or zinc, it is not intended that this be limited to the pure metals, but of course it will be understood that the metals may be provided as alloys in which the predominate metal is defined, such that the defined metal provides the predominant role in cathodic protection.

[0031] To maintain the electrical activity of the anode against the rebar, an activator is preferably provided at or adjacent to the inner anode to maintain ionic current flow, thereby reducing the tendency for electrical activity to decrease over time.

[0032] In one optional method, the activator is provided by a layer of water transport medium, distinct from the concrete, which carries the ionically conductive medium to a location at or adjacent to the inner anode. That is, when used, the water transport medium layer is typically positioned so that its bottom contacts the ionically conductive medium and extends to a location above the level of the ionically conductive medium.

[0033] Alternatively, the activator may comprise a chemically activating or strengthening agent carried with the poured grout of the type well known in the art and described in the above-referenced patents. The activator may also be disposed within or around the anode, either incorporated within the anode itself or incorporated within materials surrounding the anode in a manner known in the art.

[0034] The cover layer or jacket defines a shape spaced apart from the surface to receive grout that is poured between the cover layer and the surface. In many embodiments, the jacket remains in place to provide corrosion protection, but alternatively, the cover layer can be removed after the grout is poured, leaving the inner anode and bulk anode in place and exposing the grout for visual inspection. [Brief explanation of the drawings]

[0035] An embodiment of the present invention will now be described with reference to the accompanying drawings.

[0036] [Figure 1] 1 is a front elevation view of a pillar to which the first embodiment method of corrosion prevention according to the present invention has been applied. FIG. [Figure 2] FIG. 2 is an enlarged view of the connection box of the embodiment of FIG. 1. [Figure 3] FIG. 2 is a rear elevational view of the jacket portion of the embodiment of FIG. 1. [Figure 4] FIG. 2 is an isometric view of the jacket portion of the embodiment of FIG. 1. [Figure 5] FIG. 2 is a top view of the jacket portion of the embodiment of FIG. 1. [Figure 6] FIG. 10 is a cross-sectional view of a pillar to which a second embodiment of corrosion prevention according to the present invention is applied. [Figure 7] FIG. 10 is a longitudinal cross-sectional view of a pillar to which a third embodiment of corrosion prevention according to the present invention is applied. [Figure 8] FIG. 10 is a longitudinal cross-sectional view of a pillar to which a further embodiment of corrosion protection according to the present invention is applied, including an activator to maintain the activity of the inner anode. [Figure 9]FIG. 4 is a longitudinal section of a pillar applying a further embodiment of corrosion protection according to the present invention, in which the grout contains an activator and a bulk anode 431 is attached to the pillar independently of the coating jacket material. [Figure 10] FIG. 10 is a longitudinal section of a column applying a further embodiment of corrosion protection according to the present invention, in which the jacketing acts as an initial formwork for the grout and is subsequently removed during operation, and a bulk anode is attached to the column independently of the jacketing. DETAILED DESCRIPTION OF THE INVENTION

[0037] FIG. 1 shows a conventional reinforced concrete pillar installed in water 9, with pillar 10 having a lower end, generally designated 11, attached to a suitable support in the water, and an upper end 12 positioned to support the structure supported by the pillar. A typical pillar of this type is formed of a concrete body 13 within which are reinforcing steel members, generally designated 14. These include vertical longitudinal members 15 and transverse or perimeter hoops or ties 16. The reinforcing steel is positioned inside the pillar just below the outer surface 17 of the pillar.

[0038] The pole is mounted so that part of its length lies in the intertidal zone generally indicated at 20, with the low tide line indicated at 21 and the high tide line indicated at 22. Above the high tide line is the splash zone. Of course, the tides change and the splash height varies, but generally the area between the low tide line 21 and the top of the splash zone is the area of ​​the pole that is subject to repeated wetting and drying at any one time, depending on the height of the water around the pole.

[0039] This zone, and the area of ​​the concrete column extending upward from this zone, is particularly susceptible to corrosion because the rebar is exposed to moisture, chlorides, and oxygen, which act to break down the rebar and form corrosion products. These corrosion products can cause the concrete to expand to the point where it cracks. In addition to this cracking, corrosion of the rebar can also result in a loss of structural performance.

[0040] The technique of the present invention is intended primarily as a column repair technique, but can also be used in new construction.

[0041] The structure of the present invention includes an impermeable layer or jacket 30 attached to the column at a location outside the column's exterior surface 17. The jacket 30 can be formed of an impermeable material such as resin, plastic, fiber-reinforced plastic, or stainless steel. The jacket may be reinforced to provide structural strength to help resist concrete movement, or the jacket may be fabric or a stretchable or flexible material without such structural reinforcement so that it simply moves with the concrete. If reinforced, it may be reinforced with fibers such as glass, plastic, carbon fiber, or other materials well known to those skilled in the art. In the embodiment shown in Figures 1-5, the impermeable layer or jacket 30 is formed of sections 30A and 30B connected at joint 30C. In one embodiment, the joint is a butt flange joint, where two protruding flanges of the two sections of the jacket butt together and are secured together by bolts or screws with a layer of sealant between the two butt flanges. This completely seals the jacket around the column at the joints between the jacket sections to form a sealed sleeve around the column from the jacket's top end 31 to the jacket's bottom end 32. Other methods of sealing the joints are possible, such as tongue and groove joints, lap splice joints, and self-locking mechanical connectors.

[0042] The inside of the jacket is filled with a cementitious or polymer-based grout or other filler 33, forming a band of material around the column within the jacket. In most cases, the jacket is used as a formwork for applying the grout to the column. Prior to application, damaged concrete material can be excavated or removed to repair cracked areas, and the finished jacket can be filled with material surrounding the column to fill any depressions, cracks, or excavations in the concrete column. The grout is typically Portland cement-based, which hardens and bonds to the column's exterior surface, acting as an effective filler. Other types of fillers, including other organic and inorganic-based materials, can also be used.

[0043] While the jacket is being filled, the lower end 32 of the jacket may be closed by a forming structure or platform 35 to hold the grout in place until it cures. After the grout has cured, the bottom form may be removed to expose the bottom surface 34 of the grout, although it may remain in place. After filling, the top 31 of the jacket will generally expose the top surface 305 of the grout.

[0044] The anode of the cathodic protection system comprises a sheet anode 42 surrounding the column beneath the jacket 30. The anode 42 is connected to the rebar within the column by a conductor or wire 45, as described below. Additional connections can be made to other sections of the rebar, if necessary, depending on the electrical conductivity of the rebar. The conductor wire 45 is brazed or soldered to the zinc mesh at 451 to provide an effective connection even after some corrosion has occurred. The conductor wire may be fed directly into the anode material. The conductor wire 45 is connected to a junction box 452. The junction box can also accept connection wires from other anode sections, for example, if the jacket is formed from separate pieces as described below.

[0045] Thus, the cathodic protection system includes a bulk anode 43 provided by the sacrificial anode material and optionally an inner anode 42, rebar 14, an electrical connection 45 from the anode to the rebar, and an ionic connection from the anode to the rebar through an ionically conductive material, which may include grout and concrete, to provide cathodic protection of the rebar while causing sacrificial corrosion of the anode.

[0046] The sacrificial anode may be provided as a sheet or layer extending around the entire perimeter of the column adjacent to the outer surface of the concrete so that ionic current flows through the grout layer and into the concrete. The sacrificial anode is preferably formed as a zinc mesh or other perforated sheet, typically expanded metal. Alternatively, the sacrificial anode may be provided in the form of a solid sheet, or as a rod, strip, or individual piece. Suitable known reinforcement may be provided in the anode as part of its structure or in the next adjacent layer, such as grout.

[0047] The sacrificial anode forms a sheet inside the jacket so as to include at least a portion located above the water line indicated by 91, i.e., the water surface, and a portion located below the water line 91.

[0048] To provide an efficient method of assembling a structure for carrying out the above method, the bulk anode and jacket 30, optionally together with the inner anode, form a pre-assembled structure for common application to a concrete structure. That is, the two layers can be provided together as a wrapping to engage around a column or to be applied to the surface of a concrete structure. This common assembly or pre-assembled structure can also include a connection box 452.

[0049] More preferably, the coating layer 30 and the sacrificial anode(s) all form a pre-assembled structure for common application as an assembled structure to a concrete structure with the coating layer covering the sacrificial anode. Thus, the outer jacket 30 has the sacrificial anode formed as a layer inside the outer jacket. In this way, the structure can be easily applied to a column as a tight wrapping or as a form for pouring grout into the jacket.

[0050] An impermeable sleeve 30 around the rebar within the jacket prevents moisture from escaping from the jacket while the concrete is exposed to air, and therefore would otherwise dry out. The sleeve also prevents oxygen from diffusing to the rebar.

[0051] Alternatively, the jacket may be formed as a single piece that is wrapped around the post to provide a single overlap seal.

[0052] The jacket can be wrapped around the column and applied directly to the outer surface of the concrete. Therefore, in this configuration, no additional grout is provided, except for grout that may be provided to fill cracks or holes in the column's concrete. Thus, in intertidal and splash zones, a simple sleeve is wrapped around the column. If no repair is required, the jacket 30 is attached directly to the column without the use of any grout. In this configuration, the jacket can be provided by a fiberglass layup process, formed in place by simply applying or wrapping fiberglass sheeting and resin onto the outer surface of the column.

[0053] Other suitable plastic, rubber, organic or inorganic materials can be used as the sheet.

[0054] A bulk anode 43 made of a sacrificial material such as zinc or a zinc-based alloy generates a galvanic current in the rebar within the concrete structure, and the bulk anode 43 is positioned outside the covering layer or jacket 30 at or adjacent the lower end 32 so as to be below the surface 91 of the water 9.

[0055] The jacket may also carry at least a portion of an inner anode 42 on its inner surface, and at least one panel of the jacket may carry a bulk anode 43 on its outer surface.

[0056] 1-4, when the jacket is formed as separate panels connected together, at least one panel, when provided as part of an assembly as shown, carries both at least a portion of the inner anode 42 on its inner surface and a bulk anode on its outer surface. In the illustrated embodiment, because both panels carry both the inner anode and the bulk anode, the combined amount of anode material from both panels can provide the required corrosion protection life.

[0057] The bulk anode 43 attached to the outside of the jacket comprises a metal portion which may have two end flanges 431 as shown in FIG. 5, which are fixed to an inner connecting plate 433 through the jacket by bolts 432 so as to effectively support the heavy bulk anode on the outside without tearing or distorting the jacket.

[0058] The pre-assembled structure further includes electrical connection wires or conductors 434 for connection from the bulk anode 43 to ultimately the rebar inside the concrete structure. The wires 434 are connected to a plate 433 inside the jacket and run to a connection box 452.

[0059] Thus, the pre-assembled structure further comprises an electrical connection box 452 having connection terminals 453 for connecting from the inner anode 42 to the electrical connection(s) 45, and terminals 454 for connecting from the bulk anode to the electrical connection(s).

[0060] An electrical connection box 452 is carried within the covering layer of the pre-assembled structure and is accessible from outside the covering layer by removing covering plate 456. This allows the terminals to be disconnected if required and also provides access to the terminals for measuring current and / or voltage with appropriate probes.

[0061] Thus, the present invention can be used in a method for cathodic protection of rebar within a concrete structure located in an ionically conductive medium, wherein a first portion of the concrete structure is below the surface of the medium and in contact with the medium, a second portion of the concrete structure contiguous with the first portion is above the surface of the medium, and the concrete structure has rebar in both the first and second portions. The method includes providing a coating layer or jacket 30 positioned to cover at least a portion of at least one outer surface of the concrete structure, such that an inner surface of the coating layer is positioned adjacent to at least one outer surface of the concrete structure.

[0062] The method optionally further includes providing an inner anode 42 made of a sacrificial material for generating a galvanic current in the rebar, the inner anode being positioned between the inner surface of the cladding 30 and the outer surface 13 of the concrete structure 11.

[0063] The jacket carries the bulk anode and, optionally, the inner anode as a pre-assembled structure before being attached to the structure, and is then attached to the concrete structure, thereby attaching both the bulk anode and the optional inner anode carried thereby to the concrete structure. Electrical connections between the inner anode and the rebar, and between the bulk anode and the rebar, are also easily and automatically made by connection to the junction box. In this way, a single connection from the junction box to the rebar can be provided. Alternatively, if the rebar is not sufficiently integrally connected, additional coupling wires can be connected from the junction box to selected locations on the rebar.

[0064] FIG. 6 shows very diagrammatically an arrangement in which the jacket is formed from a plurality of separate panels 311 and 312, the method comprising connecting the panels by suitable side connection arrangements 313 to form an assembly which engages at least two surfaces of the concrete structure and wraps around the concrete, typically in the form of a jacket.

[0065] The separate panels include a plurality of flat panels 312 and a plurality of corner panels 311 that are connected together to form a square or rectangular jacket. Separate flat panels can be provided, connected to each other, and bent to surround a circular column.

[0066] At least one component or panel 312 carries at least a portion of the bulk anode 43, and optionally at least one panel carries at least a portion of the inner anode 42 as a pre-assembled structure. The panels are then fastened together, and the competitive jacket carries the bulk anode, and optionally both the inner and bulk anodes.

[0067] As mentioned above, the covering layer or jacket may include a bottom closure member 35 at the lower end 32 to prevent leakage of the grout when poured into the mold defined by the jacket.

[0068] The lower portion of the jacket, when the cover layer is installed, carries and supports the bulk anode 43 below the water surface at or adjacent the lower end 32. In this manner, the bulk anode 43 is supported against the concrete surface solely by connecting the bulk anode to the cover layer, without the need to separately mount the bulk anode on a post below the water surface.

[0069] 5 may be attached directly or indirectly to the bulk anode or its connection plate to further reinforce and support the bulk anode within the grout once the grout has been poured and hardened. In this manner, the reinforcement member extends from the inner surface of the covering layer toward the surface of the concrete into which it will be embedded when the grout is poured.

[0070] The inner anode can be pre-attached. Alternatively, however, particularly for strip and rod anodes and modular jackets, the inner anode can be supplied separately. In this way, the inner anode can be installed on the surface of the column, the wiring can be connected, and then the jacket can be attached to the inner anode and column, so that the jacket is not in the way.

[0071] As mentioned above, the bulk anode 43 is preferably formed from aluminum or an aluminum-based alloy, but can also be formed from zinc or a zinc-based alloy if potential toxicity is not a concern.

[0072] Turning now to the configuration shown in Figure 8, an activator is provided at or adjacent to the inner anode to maintain the flow of ionic current. In this embodiment, the activator is provided by a layer 50 of a water transport medium, different from concrete, that transports an ionically conductive medium, i.e., seawater, to the location of or adjacent to the inner anode.

[0073] That is, within jacket 30, in addition to the concrete, grout, and anodes, is a layer 50 of water transport medium. This is disposed adjacent to the sacrificial anode layer and preferably extends from a position below water line 91 to a position above the water line so as to be in contact with the water. Thus, as shown, layer 50 extends from an exposed bottom portion 502 beyond the bottom of the jacket to an exposed top portion 502 above the top of the jacket. This layer acts to provide additional wetting with water from below the water line of the structure, at least in the concrete portion above the water line, to supply additional water into the grout, to the sacrificial anodes, and to the interior of the jacket to promote the generation of ionic current.

[0074] The water transport medium serves to provide an improved, low-resistance ionic conduction path between the sacrificial anode and the rebar. In situations where the water transport medium is exposed to saltwater, the improvement in ionic conduction is further enhanced. The resistance through the concrete between the sacrificial anode and the rebar decreases, increasing the current. As a result, the rebar closer to the anode is better protected, and the current sufficient to protect the rebar can travel a longer distance, increasing the area of ​​protection.

[0075] Further details of the water transport or wicking layer can be found in U.S. Patent No. 9,447,506, issued September 20, 2016 to inventor Whitmore, the disclosure of which may be referenced for further details.

[0076] Thus, the water transport medium layer 50 is positioned so that the bottom of the water transport medium layer is in contact with the ionically conductive medium and the water transport medium layer extends to a position above the level of the ionically conductive medium. The coating layer, inner anode structure, and water transport medium layer preferably form a pre-assembled structure for common application to the concrete structure. However, the elements of the structure can alternatively be applied separately. The location of the wicking layer 50 is preferably on one or both sides of the anode, and may be located on the jacket so as to be supported by the jacket.

[0077] The water transport layer or wicking material may also provide the advantage of potentially acting as a separator between the anode and the concrete or grout, an advantage that is not limited to above the water line.

[0078] Turning now to the configuration shown in Figure 9, in this configuration the activator or reinforcement comprises a chemically active substance 60 carried in grout or filler material 33 within a covering layer or jacket 30. That is, the jacket 30 defines a shape spaced from the surface of the column to receive grout material 33 poured between the jacket and the surface of the column, and the activator 60 is provided within the grout.

[0079] As described in the above-cited US Pat. No. 7,520,974, the anode and jacket may therefore carry reinforcement materials.

[0080] For example, the pH level and the presence of humectants enhance the maintenance of the current so that the current can be maintained for long periods of time, ranging from 5 to 20 years.

[0081] In addition to the above materials, a humectant or deliquescent substance is applied to the mortar or the anode body itself. Suitable substances include Ca(NO3)2, CaCl2, LiNO3, CaNO2, MgCl2, Na2SO4, and many others familiar to those skilled in the art. Such humectants are primarily in solid or powder form, but can also be dissolved to form an aqueous solution. Alkaline substances adjusted to maintain a pH greater than 12 can also be used. Further details of such substances and humectants are disclosed in other patents of Whitmore, the present inventor, or their assignees, including the present applicant.

[0082] The presence of the humectant acts to absorb sufficient moisture to maintain electrical conductivity around the anode, keeping the anode / filler interface electrochemically active, ensuring sufficient current output is maintained over the life of the anode. The presence of the humectant also increases the amount of current flow. Although the mortar 21 is embedded within the jacket and therefore not exposed to the atmosphere, and the humectant is fixedly bonded to the mortar, the absorption of moisture into the humectant has been found to be sufficient to enhance current output maintenance and prevent premature current output degradation during long-term operation and prior to anode depletion.

[0083] The bulk anode 43 generally does not provide or require such reinforcement because it is located within the aggressive action provided by seawater, both in terms of the high conductivity through seawater and the chlorides present, but such reinforcement or activator can be provided if desired.

[0084] For example, the active agent can be carried by the inner anode.

[0085] For example, the active agent includes a chemically active substance that can be carried with the coating layer.

[0086] As described above, the coating layer prior to application carries both the inner anode and the bulk anode, the coating layer is attached to the concrete structure so as to attach both the inner anode and the bulk anode carried by the coating layer to the concrete structure, and the coating layer defines a shape spaced from the surface to receive grout material poured between the coating layer and the surface.

[0087] Referring now to Figure 10, an alternative configuration is shown in which the covering layer or jacket 30 is removed after pouring, leaving the inner anode and poured grout in place to expose the grout material. In this case, the bulk anode 43 is separately attached to the column and remains in place after the grout material is poured and the jacket is removed. In this case, the inner anode 42 is preferably spaced apart from the outer surface of the case grout as the grout is poured, allowing the poured grout surface to be exposed and out of the way. This configuration may be preferred in some installations because it allows the outer surface to be exposed and visible rather than hidden under the jacket.

Claims

1. 1. A method for cathodic protection of reinforcing steel within a concrete structure located in an ionically conductive medium, the method comprising: a first portion of the concrete structure below a surface of the medium and in contact with the medium; a second portion of the concrete structure contiguous with the first portion and above the surface of the medium; and the concrete structure having the reinforcing steel in both the first portion and the second portion, providing a coating layer disposed over at least a portion of at least one exterior surface of the concrete structure, the interior surface of the coating layer being disposed adjacent to the at least one exterior surface; providing a bulk anode made of a sacrificial material for generating a galvanic current in the rebar within the concrete structure, the bulk anode being positioned outside the coating layer and below the surface of the medium; carrying the bulk anode with the coating layer before being applied to at least a portion of the at least one outer surface of the concrete structure for coating; attaching the coating layer to the concrete structure so as to attach the bulk anode supported on the coating layer to the concrete structure; providing an electrical connection between the bulk anode and the rebar such that an ionic current flows between the bulk anode and the rebar, tending to inhibit corrosion of the rebar; A method comprising:

2. 2. The method of claim 1, further comprising providing an inner anode made of a sacrificial material for generating a galvanic current in the rebar, the inner anode being positioned between the inner surface of the coating layer and the at least one outer surface of the concrete structure.

3. 3. The method of claim 2, wherein the coating layer is attached to the concrete structure before being applied to the at least a portion of the at least one outer surface of the concrete structure for coating, such that the coating layer carries both the inner anode and the bulk anode and both the inner anode and the bulk anode carried by the coating layer are attached to the concrete structure.

4. 3. The method of claim 2, wherein the covering layer comprises a plurality of separate panels, the method including connecting the panels to form an assembly that engages at least two surfaces of the concrete structure.

5. The method of claim 4 , wherein the separate panels include a plurality of flat panels and a plurality of corner panels for connecting together to engage a plurality of surfaces of the concrete structure.

6. 6. The method of claim 4 or 5, wherein at least one panel carries at least a portion of the inner anode on an inner surface and at least one panel carries the bulk anode on an outer surface.

7. 6. The method of claim 4 or 5, wherein at least one panel carries at least a portion of the inner anode on an inner surface and the bulk anode on an outer surface.

8. A method according to any one of claims 1 to 5, wherein the concrete structure comprises a pillar and the covering layer, when installed, forms a jacket surrounding the pillar.

9. 6. The method of any one of claims 1 to 5, wherein the concrete structure comprises a pillar, and the coating layer comprises a plurality of separate parts each surrounding a portion of the pillar, the plurality of separate parts being attached together to form a jacket surrounding the pillar, and at least one of the plurality of separate parts constituting at least part of the bulk anode as a pre-assembled structure.

10. The method according to any one of claims 1 to 5, wherein the coating layer constitutes at least one coating part together with the bulk anode as a pre-assembled structure.

11. 11. The method of claim 10, wherein the pre-assembled structure includes electrical connections from the bulk anodes to connect to the rebar within the concrete structure.

12. The method of claim 11 , wherein the pre-assembled structure comprises an electrical connection box including connection terminals for connecting to the electrical connections from the bulk anode.

13. 13. The method of claim 12, wherein the electrical connection box is carried by the coating layer and pre-connected to the electrical connections from the bulk anode.

14. The method of claim 13 , wherein the electrical junction box is mounted inside the cover layer and is accessible from outside the cover layer.

15. The method according to any one of claims 1 to 5, wherein the bulk anode is attached to the outside of the covering layer and a connecting plate is attached to the inside.

16. A method according to any preceding claim, wherein the covering layer defines a shape spaced apart from the surface to receive grout poured between the covering layer and the surface.

17. 17. The method of claim 16, further comprising providing a support member extending from the bulk anode attached to the cover layer into the grout to support the bulk anode when the grout has hardened after being poured.

18. A method according to any one of claims 1 to 5, wherein the bulk anode is supported against the surface of the concrete structure by connection of the bulk anode to the coating layer.

19. The method of any one of claims 1 to 5, wherein the bulk anode comprises aluminum.

20. The method of claim 2, wherein the inner anode comprises zinc.

21. 1. A method for cathodic protection of reinforcing steel within a concrete structure located in an ionically conductive medium, the method comprising: a first portion of the concrete structure below a surface of the medium and in contact with the medium; a second portion of the concrete structure contiguous with the first portion and above the surface of the medium; and the concrete structure having the reinforcing steel in both the first portion and the second portion, providing a coating layer disposed over at least a portion of at least one exterior surface of the concrete structure, the interior surface of the coating layer being disposed adjacent to the at least one exterior surface; providing an inner anode made of a sacrificial material for generating a galvanic current in the rebar, the inner anode being positioned between the inner surface of the coating layer and the at least one outer surface of the concrete structure; providing a bulk anode made of a sacrificial material for generating a galvanic current in the rebar within the concrete structure, the bulk anode being positioned outside the coating layer and below the surface of the medium; attaching the coating layer to the concrete structure; providing electrical connections between the inner anode and the rebar and between the bulk anode and the rebar so that ionic current flows between the inner anode and the rebar and between the bulk anode and the rebar, tending to inhibit corrosion of the rebar; Including, The method wherein the bulk anode comprises aluminum.

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