PROTECTED REINFORCED CONCRETE STRUCTURE

Abstract

A reinforced concrete structure comprising a hardened concrete containing at least one steel reinforcement, a plurality of anode cavities and interconnecting slots formed within the hardened concrete, with the interconnecting slots interconnecting adjacent anode cavities with one another. A discrete galvanic anode is installed within each of the anode cavities. At least one connector for connecting the plurality of discrete galvanic anodes with the at least one steel reinforcement. A plurality of interconnecting galvanic anodes which each comprises a metallic element which has an interconnecting connector extending from opposed ends thereof. Each of the interconnecting galvanic anodes is installed within a respective interconnecting slot. First and second ends of the interconnecting connector are respectively connected to adjacent first and second discrete galvanic anodes. Each interconnecting galvanic anode contains sufficient sacrificial metal to increase a total protection current delivered to the steel reinforcement.

Claims

1. A reinforced concrete structure comprising: a hardened concrete containing at least one steel reinforcement, a plurality of anode cavities being formed within the hardened concrete, a plurality of interconnecting slots being formed within the hardened concrete, and one of the plurality of interconnecting slots interconnecting two adjacent anode cavities with one another, a plurality of discrete galvanic anodes, and one of the plurality of discrete galvanic anodes being installed within a respective one of the plurality of anode cavities, and at least one connector for connecting the plurality of discrete galvanic anodes with the at least one steel reinforcement, wherein the reinforced concrete structure further includes a plurality of interconnecting galvanic anodes which each comprises galvanic metal element which has an interconnecting connector extending from both opposed ends thereof, each one of the plurality of interconnecting galvanic anodes is installed within a respective one of the interconnecting slots, a first end of the interconnecting connector is electrically connected to a first adjacent discrete galvanic anode and a second end of the interconnecting connector is electrically connected to a second adjacent discrete galvanic anode.

2. The reinforced concrete structure according to claim 1, wherein each of the metallic metal comprises a strip of metal which is folded around the interconnecting connector which has a length longer than a length of the strip of metal such that opposed ends of the interconnecting connector extend out from opposite ends of the strip of metal with the interconnecting connector being located along one edge of the strip of metal.

3. The reinforced concrete structure according to claim 1, wherein each interconnecting galvanic anode has a length and a thickness and the length of the interconnecting galvanic anodes is greater than a diameter of each of the plurality of the anode cavities and the thickness of the interconnecting galvanic anodes is less than a width of the interconnecting slot.

4. The reinforced concrete structure according to claim 1, wherein each of the discrete galvanic anodes is received within a respective anode cavity and embedded therein with a backfill, and each of the interconnecting galvanic anodes is received within a respective interconnecting slot and embedded therein with a backfill.

5. The reinforced concrete structure according to claim 1, wherein the plurality of discrete galvanic anodes and the plurality of interconnecting galvanic anodes are electrically connected together and with the reinforcing steel by the at least one connector to form an electrical circuit for protection of the steel reinforcement.

6. The reinforced concrete structure according to claim 1, wherein the plurality of discrete galvanic anodes and the plurality of interconnecting galvanic anodes each comprise a metal less noble than the steel reinforcement such that the discrete galvanic anodes and the interconnecting galvanic anodes each oxidize in order to protect the steel reinforcement.

7. The reinforced concrete structure according to claim 1, wherein each galvanic interconnecting anode has a minimum charge capacity of 30 kC (kilo coulombs).

8. The reinforced concrete structure according to claim 2, wherein the strip of metal is folded about and around the interconnecting connector so as to sandwich the interconnecting connector between overlapped sides of the strip of metal with the interconnecting connector extending adjacent and along the fold line of the strip of metal.

9. The reinforced concrete structure according to claim 1, wherein each electrical connection to the at least one steel reinforcement comprises a hole formed into the at least one steel reinforcement with the at least one connector connected to the at least one steel reinforcement via a rivet.

10. A method of protecting at least one steel reinforcement located within hardened concrete of a reinforced concrete structure, the method comprising: forming a plurality of anode cavities within the hardened concrete, forming a plurality of interconnecting slots within the hardened concrete, with each one of the plurality of interconnecting slots interconnecting two adjacent anode cavities with one another, providing a plurality of discrete galvanic anodes, and installing a respective one of the plurality of discrete galvanic anodes within a respective one of the plurality of anode cavities, providing at least one connector for connecting the plurality of discrete galvanic anodes with the at least one steel reinforcement, providing a plurality of interconnecting galvanic anodes, and each of the plurality of interconnecting galvanic anodes comprising a metallic element which has an interconnecting connector extending from both opposed ends thereof, and each of the plurality of interconnecting galvanic anodes containing a sufficient quantity of a sacrificial metal to increase a total protection current delivered to the steel reinforcement in the reinforced concrete structure, installing each one of the plurality of interconnecting galvanic anodes within a respective one of the interconnecting slots, electrically connecting a first end of the interconnecting connector to a first adjacent discrete galvanic anode and electrically connecting a second end of the interconnecting connector to a second adjacent discrete galvanic anode, and embedding each one of the plurality of interconnecting galvanic anodes and the plurality of discrete galvanic anodes in a backfill.

11. The method according to claim 10, further comprising using a strip of metal as the metallic metal, and folding the strip of metal around the interconnecting connector which has a length longer than a length of the strip of metal such that opposed ends of the interconnecting connector extend out from opposite ends of the strip of metal, with the interconnecting connector being located along one edge of the strip of metal.

12. The method according to claim 10, further comprising forming each interconnecting galvanic anode with a length and a thickness such that the length of the interconnecting galvanic anodes is greater than a diameter of each of the plurality of the anode cavities and the thickness of the interconnecting galvanic anodes is less than a width of the interconnecting slot.

13. The method according to claim 10, further comprising inserting the backfill within each of the respective anode cavities and then installing one of the plurality of discrete galvanic anodes therein such that the discrete galvanic anode is completely embedded within the backfill contained within the respective anode cavity, and inserting the backfill within each of the respective interconnecting slots and then installing one of the plurality of interconnecting galvanic anodes therein such that the interconnecting galvanic anode is completely embedded within the backfill contained within the respective interconnecting slot.

14. The method according to claim 10, further comprising electrically connecting the plurality of discrete galvanic anodes and the plurality of interconnecting galvanic anodes together and to the reinforcing steel by the at least one connector to form an electrical circuit for protection of the steel reinforcement.

15. The method according to claim 10, further comprising forming each of the plurality of discrete galvanic anodes and each of the plurality of interconnecting galvanic anodes from a metal less noble than the steel reinforcement such that the discrete galvanic anodes and the interconnecting galvanic anodes each oxidize in order to protect the steel reinforcement.

16. The method according to claim 10, further comprising designing each of the galvanic interconnecting anodes to have a minimum charge capacity of 30 kC (kilo coulombs).

17. The method according to claim 11, further comprising folding the strip of metal about and around the interconnecting connector so as to sandwich the interconnecting connector between overlapped sides of the strip of metal with the interconnecting connector extending adjacent and along the fold line of the strip of metal.

18. The method according to claim 17, further comprising forming each electrical connection to the at least one steel reinforcement via a hole formed into the at least one steel reinforcement with the at least one connector connected to the at least one steel reinforcement via a rivet.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] This invention is now illustrated further with reference by way of example to the drawings in which:

[0038] FIG. 1(a) diagrammatically shows a partially assembled interconnecting galvanic anode.

[0039] FIG. 1(b) diagrammatically shows an assembled and completed interconnecting galvanic anode.

[0040] FIG. 2 diagrammatically shows an arrangement of anode cavities and interconnecting slots formed in a concrete structure to commence installation of the anode system.

[0041] FIG. 3 diagrammatically shows a section of a reinforced concrete structure through a line of installed discrete galvanic anodes and interconnecting galvanic anodes of an installed anode system.

[0042] FIG. 4 shows, as a function of time, the integrated current (charge) off a discrete galvanic anode and an interconnecting galvanic anode.

[0043] It will be appreciated that the combinations of features shown in individual figures and described with reference to specific examples below are purely by way of exemplary. As those skilled in the art will readily understand, specific features of any of the examples described and shown may be used in combination with a feature, or a subset of features of any other specific examples to the extent that it is technically feasible.

EXAMPLE 1

[0044] As shown in FIGS. 1(a) and 1(b), a metallic strip 8, having a length measuring 250 mm (9.843 inches) and a width measuring 20 mm (0.787 inches), for example, is cut from a sheet of zinc having a thickness of 0.25 mm (0.0098 inches) or so. It is to be appreciated that the overall length, width and/or thickness of the metallic strip 8 can vary depending upon the particular application. The metallic strip 8 is then partially folded in half to produce an “L” shaped section having length of 250 mm (9.843 inches) with two equal sides or legs, each measuring 10 mm (0.394 inches) wide, as generally shown in FIG. 1(a)). Thereafter, a 400 mm (15.748 inches) long 1.2 mm (0.074 inches) diameter connector (e.g., a titanium wire) 9, for example, is placed inside of the “L” shaped section of the metallic strip 8, generally along the fold line, with about a 75 mm (2.953 inches) long section of the connector 9 extending out from each opposed end of the metallic strip 8. The metallic strip 8 is then completely folded about and around the connector 9 (FIG. 1(b)) so as to sandwich the connector 9 between the sides or legs of the metallic strip 8, with the connector 9 generally extending adjacent and along the fold line of the metallic strip 8. Next, the metallic strip 8 is rolled flat to produce a metallic (zinc) ribbon having a length of 250 mm (9.843 inches), a width of 10 mm (0.394 inches) and a maximum thickness of about 1.7 mm (0.067 inches), normally along the fold line where the connector 9 is sandwiched between the two sides or legs of the metallic (zinc) strip 8 and forced into good electrical contact with the metallic strip 8. As noted above, approximately a 75 mm (2.953 inches) section of the connector 9 extends from each opposed end of the metallic (zinc) ribbon to complete formation of the interconnecting galvanic anode 16. The metallic (zinc) strip generally lies and defines a plane of the interconnecting galvanic anode 16. This arrangement provides one example of the interconnecting galvanic anode 16 with a galvanic metal strip 8, and the connector 9 integrated into the anode such that opposed ends of the connector 9 extend from each end of the interconnecting galvanic anode 10. As described above, the width of the interconnecting galvanic anode 16 is at least 5 times the thickness of the interconnecting galvanic anode 16.

[0045] FIG. 2 shows a concrete surface 1, with drilled holes that form anode cavities 2 (only three of which are shown in this Figure) and cut slots that form interconnecting slots 3 (only four of which are shown in this Figure). The interconnecting slots 3 extend between and interconnect a pair of adjacent cavities 2 with one another. Each anode cavity 2 has a diameter 4 and each slot has a width 5. While all of the anode cavities 2 are generally shown as having the same diameter 4, it is to be appreciated that the diameter, shape and/or size of the anode cavities 2 can vary from one another without departing from the spirit and scope of the present disclosure. In addition, while all of the interconnecting slots 3 are shown as having the generally same width 5 and length, it is to be appreciated that the width, shape, depth and/or length of the cavities can vary from one another without departing from the spirit and scope of the present disclosure.

[0046] As shown for example in FIG. 2, the anode cavities 2 were drilled with a masonry drill bit to have a depth of 100 mm (3.937 inches) or so and have a diameter 4 of 30 mm (1.181 inches) or so. In addition, the interconnecting slots 3 were cut with an angle grinder and have a width of 6 mm (0.236 inches) or so and a depth of 25 mm (0.984 inches) or so. The concrete structure was an aged reinforced concrete slab measuring 1.2 m (47.24 inches) by 1.2 m (47.24 inches) by 0.18 m (7.09 inches) and the anode cavities 2, were located at 300 mm (11.811 inches) on center along the line of the reinforcing steel.

[0047] FIG. 3 diagrammatically shows a section through a reinforced concrete structure 10. The structure includes a plurality of anode cavities 11 (only three of which are shown in this Figure), and a plurality of interconnecting slots 12 (only four of which are shown in this Figure). Also a single reinforcing steel bar 13 is diagrammatically shown embedded within the concrete. A single discrete galvanic anode 15 is installed within each one of the respective anode cavities 11. A respective interconnecting galvanic anode 16 is located and installed within each of the interconnecting slots 12, located between adjacent anode cavities 11, which each accommodate a respective discrete galvanic anode 15. Each interconnecting galvanic anode 16 has a thickness 17 and a length 18. Via at least one connector(s) 19, the galvanic anodes 15, 16 are electrically connected together and to the reinforcing steel 13 to form an electrical circuit. In this example, each one of the discrete galvanic anodes 15 is a bar of zinc having a diameter of 18 mm (0.709 inches) and a length of 75 mm (2.953 inches) which is cast around a titanium wire or connector 19 which extends from one (e.g., top) end of the discrete galvanic anode 15. The interconnecting galvanic anode 16 is shown in FIG. 1 and described in further detail above.

[0048] A conventional backfill (e.g., plaster also known as gypsum) is used to embed each one of the discrete galvanic anodes 15 and each one of the interconnecting galvanic anodes 16. Typically the space above the backfill/plaster in the cavities and slots is filled with a sand cement mortar with a ratio of 1 to 1 so as to completely cover each one of the embedded discrete galvanic anodes 15 and interconnecting galvanic anodes 16.

[0049] A 10 ohm resistor is installed between a discrete galvanic anode 15 and the connecting wires 19, and between the interconnecting galvanic anode 16 and the connecting wires 19 and used as a current sensor to measure the current off each one of the discrete galvanic anodes 15 and each one of the interconnecting galvanic anode 16 to ensure sufficient electrical connection.

[0050] In the arrangement described above, following installation, each one of the discrete galvanic anodes 15 and each one of the interconnecting galvanic anodes 16 can deliver 2 mA. The current was integrated to calculate the charge delivered. This is shown in FIG. 4. This data indicates that the use of the interconnecting galvanic anodes 16 significantly increases the total protection current delivered to the steel 13 in a reinforced concrete structure while minimizing the amount of drilled holes or cavities.

INDUSTRIAL APPLICABILITY EXAMPLE

[0051] By way of example the following text in this section headed “Industrial Applicability” may be used in a technical data sheet describing a specific galvanic interconnecting anode product and its installation in a use of the above described invention.

[0052] General Description

[0053] Galvanic interconnecting anodes are located in slots (e.g., chases) between conventional discrete galvanic anodes 15. The galvanic interconnecting anodes 16 provide an additional high current phase to galvanic corrosion protection systems. The galvanic interconnecting anode 16 increases the initial restorative properties of a galvanic system and arrest corrosion in sound but contaminated reinforced concrete (BS EN1504 section 9 Principle 10). The galvanic interconnecting anode 16 is to be embedded into the interconnecting slots 12 which are normally formed between adjacent discrete galvanic anodes 15 and connected to the steel reinforcement 13 via a recessed feeder wiring or connector 19.

[0054] The galvanic interconnecting anode 16 may be ribbon shaped and have a width of 10 mm (0.394 inches), a length of 250 mm (9.843 inches) and a thickness of 1.5 mm (0.059 inches) with a continuous, uncoated, stainless steel wire or titanium wire protruding from both opposed ends of the galvanic interconnecting anode 16. This wire will act as the wiring for the conventional discrete galvanic system that the galvanic interconnecting anode 16 will be used in combination with.

[0055] One galvanic interconnecting anode 16 preferably has a minimum charge capacity of 30 kC (kilo coulombs) and preferably contains a minimum of 11 grams of zinc alloy. If desired, the galvanic interconnecting anode may be coated with an activator. The galvanic interconnecting anode 16 may be pre-connected to a stainless steel or titanium wire 9. The galvanic interconnecting anode 16 may be supplied as a string of pre-connected anodes.

[0056] It is to be appreciated that the embedment material (e.g., the backfill), for the galvanic interconnecting anodes, may be pre-mixed, single component specially formulated mortar provided in sealed tubes. The embedment material preferably remains pliable for more than 48 hours following installation. The backfill preferably has sufficient ionic conductivity to facilitate current delivery from the anode unit for the intended and designed service life. The backfill dispensing equipment preferably has a nozzle to allow the application of the backfill to the base of the interconnecting slot 3, 12 to dispel any air from the base of the interconnecting slot 3, 12.

[0057] Installation of Galvanic Interconnecting Anodes

[0058] Good practice requires that the reinforcement continuity should preferably be proven on site by measuring the electrical resistance between reinforcing steel bars 13 exposed in locations across the structure, including between reinforcing steel bars 13 exposed during concrete repairs or other works, following the method and acceptance criteria as specified in BS EN 12696:2016, clause 7.1. It is important to ensure that any electrically discontinuous steel should preferably be made continuous. The location of steel reinforcement, in the areas to be protected, should preferably be established to confirm that the detail in a design is appropriate. The concrete cover over the steel to be protected should preferably be determined to ensure a minimum cover, 30 mm (1.181 inches) in this example, for the purposes of installing the galvanic interconnecting anodes 16.

[0059] It is to be appreciated that the electrical connections, to the reinforcing steel 13, may be formed by removing a small area of the concrete cover to expose a small section of this steel 13, drilling a 4 mm (0.157 inches) diameter hole, for example, into this steel 13 and then riveting the feeder wire or connector 19, via a 3 mm (0.118 inches) stainless steel pop rivet (not in shown), in this drilled hole. Good practice requires that preferably a minimum of two steel reinforcement connections are made per zone of galvanic anodes 15, 16. The continuity between the feeder wire or connector 19 and steel reinforcement 13 should preferably be checked using a multimeter. Generally, electrical continuity is confirmed if a resistance of less than 1 ohm is measured.

[0060] The interconnection slots 3, 12 (e.g., chases), having width of 4 mm (0.157 inches) and a depth of 25 mm (0.984 inches) for linking or connecting the conventional discrete galvanic anode cavities 11 to one another, may be prepared to receive the galvanic interconnecting anodes 16 and the connection wires or connectors 19. All of the interconnecting slots 12 should preferably be free of dust, debris and/or rubble, prior to installation of the galvanic interconnecting anodes 16 and embedment materials or backfill within the interconnection slots 12 (e.g., chases).

[0061] The galvanic interconnecting anodes 16, in this example, are to be installed in these interconnecting slots 12 and used to link or connect conventional discrete galvanic anodes 15. One galvanic interconnecting anode 16 may be placed generally in the center of an interconnecting slot 12 between first and second adjacent discrete galvanic anodes 15. A wire connector 19 attached to the length of an edge of the galvanic interconnecting anode 16 may be located within the interconnecting slot 12 on the concrete surface side of the slot.

[0062] Prior to installation, a spray bottle, or some other suitable water dispensing device or apparatus, technique or method, may be used to pre-soaked each of the interconnecting slots 12 with water for a minimum of 15 minutes. Excess water, contained in the base of the interconnecting slots 12, should preferably be removed prior to the application of the backfill thereto. The backfill may be applied into each one of the interconnecting slots 12 using a sealant gun and a small diameter nozzle to allow access to the base of the interconnecting slot 12. A spatula may be used to press and force the backfill into the interconnecting slot and assist with expelling any entrapped air from the base of the interconnecting slot 12 and ensure good electrical conductivity.

[0063] After injection of the embedment material or backfill at each anode site, the galvanic interconnecting anode 16 may be placed into the interconnecting slot 12 and inserted such that the backfill (embedment material) completely encapsulates the entire galvanic interconnecting anode 16, ensuring that the material (backfill) preferably flows to about 15 mm (0.591 inches) from the plane defined by the concrete surface. Each end of the connecting wire 9, 19, extending from opposed ends of the galvanic interconnecting anode 16, is then preferably utilized to connect to one of the adjacent discrete galvanic anodes 15 located on either side of the interconnecting slot 12. In this preferred example, the connector wires 19, of the galvanic interconnecting anode 16, act as the wiring to connect to other components, e.g., the anodes, the steel, etc., to assist with completing the anode system.

[0064] It is to be appreciated that the installation of the associated conventional discrete anodes should otherwise preferably be undertaken in accordance with their conventional installation requirements.

[0065] To complete installation in this example, the remaining 15 mm (0.591 inches) or so at the top of each interconnecting slot 12, plus the cavities formed, for example, to expose the steel reinforcement 13 in order to make steel connections, should preferably be filled with an appropriate low shrink BS EN 1504 compliant repair mortar applied and cured as per the manufacturer's instructions.

[0066] Note, the above example covers a specific installation and specific galvanic interconnecting anode design. The installer should preferably satisfy himself/herself that the details above apply to his/her particular work environment and that the same is in compliance with all relevant regulations and standards.

[0067] Examples of suitable backfills, for use with the present disclosure, are disclosed in U.S. Pat. No. 8,002,964. The backfill may also be a powder mixed with water to produce a paste when installing the sacrificial anode assembly, an example of which would be a weak air entrained cement mortar paste. The backfill preferably retains its viscous and pliable properties for at least 48 hours and more preferably the backfill retains these properties for a longer period of time (e.g., at least one week and more preferably at least one month) as this feature renders the backfill practical for storage within a container, such as a cartridge, for an extended period of time. One example of such a suitable backfill is a lime mortar paste.