EMBEDDED FOUNDATION PROTECTION SYSTEM

Abstract

A passive cathodic protection process for preservation of em bedded metallic foundations entails embedding a wrap around a metallic foundation. The wrap has an outer sheath and an inner absorbent mat to be in direct contact with the metallic foundation. The is also mat hydrophobic. The wrap is subsumed such that an upper edge of the wrap is accessible. An oil-based metallic soap is injected via the upper edge to impregnate the mat. The metallic soap is selected from a set of metallic soaps such that the metal of the metallic soap is more electropositive than the metal of the metallic foundation such that the metallic soap acts as an anodic solution for galvanic exchange with metal within the em bedded metallic foundation for the passive cathodic protection thereof. For example, zinc naphthenate may be selected for steel or aluminium foundations thereby allowing for both passive cathodic protection and biocidal action.

Claims

1. A passive cathodic protection process for preservation of embedded metallic foundations, the process comprising: applying a wrap around an embedded metallic foundation, the wrap comprising an outer sheath and an inner absorbent mat to be in direct contact with the metallic foundation, the mat being hydrophobic, subsuming the embedded foundation and wrap such that an upper edge of the wrap is accessible, and injecting an oil-based metallic soap via the upper edge to impregnate the mat and wherein the metallic soap is selected from a set of metallic soaps such that the metal of the metallic soap is more electropositive than the metal of the metallic foundation such that the metallic soap acts as an anodic solution for galvanic exchange with metal within the embedded metallic foundation for the passive cathodic protection thereof.

2. A process as claimed in claim 1, wherein the metallic soap is a metal naphthenate.

3. A process as claimed in claim 2, wherein the metallic foundation comprises steel.

4. A process as claimed in claim 3, wherein the metallic soap comprises a metal naphthenate selected from the group of metal naphthenates comprising zinc naphthenate and aluminium naphthenate.

5. A process as claimed in claim 2, wherein the metallic foundation comprises aluminium.

6. A process as claimed in claim 5, wherein the metallic soap comprises zinc naphthenate.

7. A process as claimed in claim 1, wherein the absorbent mat comprises polypropylene.

8. A process as claimed in claim 7, wherein the absorbent mat comprises polypropylene fibre.

9. A process as claimed in claim 8, wherein the polypropylene fibre is unwoven.

10. A process as claimed in claim 1, wherein the sheath comprises plastic comprising at least one of polyethylene and PETE.

11. A process as claimed in claim 10, wherein the sheath comprises a copper foil laminate.

12. A process as claimed in claim 11, wherein the copper foil laminate is laminated between plastic sheets.

13. A process as claimed in claim 11, wherein the copper foil sheet is between 10-30 m thick.

14. A process as claimed in claim 12, wherein the copper foil sheet is 18 m thick.

15. A process as claimed in claim 1, wherein wrap is left in place for more than two years.

16. A process as claimed in claim 1, wherein wrap is left in place for more than five years.

17. A process as claimed in claim 1, wherein the process further comprises periodically injecting a replenishment of oil-based metallic soap via the upper edge.

18. A process as claimed in claim 18, wherein the replenishment is injected every 5-10 years.

19. A wrap for the passive cathodic protection of a metallic foundation, the wrap being of a cyclindrical configuration for being subsumed around a metallic foundation, the wrap having an inner absorbent mat and an outer protective sheath for the protection of the inner absorbent mat, the inner absorbent mat being hydrophobic, the inner absorbent mat configured for being in direct contact with the metallic foundation when installed, the mat impregnated with a metallic soap selected from a set of metallic soaps such that metal of the metallic soap is more electropositive than metal of the metallic foundation to be preserved such that a galvanic exchange occurs for the passive cathodic protection of the metallic foundation.

20. A wrap as claimed in claim 19, wherein the metallic foundation comprises steel and wherein the metallic soap is zinc naphthenate.

21. A wrap as claimed in claim 20, wherein the absorbent mat comprises polypropylene.

22. A wrap as claimed in claim 20, wherein the sheath comprises plastic comprising at least one of polyethylene and PETE.

23. A wrap as claimed in claim 22, wherein the sheath comprises a copper foil laminate.

24. A wrap as claimed in claim 23, wherein the copper foil laminate is laminated between sheets of plastic.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0039] FIG. 1 shows an installed wrap for the preservation of a structure foundation;

[0040] FIG. 2 shows a wrap supply sheet roll in accordance with an embodiment;

[0041] FIG. 3 illustrates galvanic exchange occurring between the wrap and a metallic foundation in accordance with an embodiment;

[0042] FIG. 4 illustrates the installation and replenishment of the wrap in accordance with an embodiment;

[0043] FIG. 5 shows a cross-sectional elevation view of the installed wrap in accordance with an embodiment; and

[0044] FIG. 6 illustrates a process for the preservation of embedded foundations in accordance with an embodiment.

DESCRIPTION OF EMBODIMENTS

[0045] FIG. 1 shows a wrap 100 subsumed around a foundation of a structure 104, such as a utility pole.

[0046] The wrap 100 comprises a hydrophobic mat 101, preferably of polypropylene. The mat 101 is further preferably polypropylene fibre and yet further preferably unwoven fibre.

[0047] The wrap 100 has a protective sheath 103 which may comprise plastic sheeting. The plastic sheeting may comprise polyethylene.

[0048] The hydrophobic mat 101 is impregnated with preservative for the preservation of the foundation of the structure 104.

[0049] The wrap 100 may be subsumed within the ground surrounding the structure 104 such that an upper edge thereof is accessible for replenishment such that the wrap 100 may remain subsumed, typically enduring the service life of the structure 104.

[0050] FIG. 2 shows an embodiment wherein the wrap 101 is formed from a continuous roll of sheet 105 which is cut to a length according to the diameter of the structure 104. With reference to FIG. 1, the edges of a cut sheet portion may be sealed with tape 105 or similar in a cylindrical fashion to surround the foundation such that the mat 103 directly contact the foundation for exposure to preservative.

[0051] In embodiments, the hydrophobic mat 103 may comprise a longitudinal narrowing 108 which locates towards the apparatus of the wrap 100 when installed. The longitudinal narrowing 108 encourages the preservative to dwell at the upper portion of the wrap 100, thereby enhancing the coverage of the reserved of along the length of the foundation.

[0052] With reference to FIG. 2, the protective sheath 103 may comprise plastic sheets of polyethylene or Polyethylene terephthalate (PETE). In the embodiment shown, the sheath 103 may comprise an outer plastic sheet 109 and a metal foil laminate 111, such as of copper for enhanced oligodynamic effect to preserve the plastic sheet 109. The metal foil laminate 111 may further offer vapour barrier effect to prevent the preservative from migrating to the surrounds. An inner plastic sheet 110 may be provided also, cooperating with the outer plastic sheet 119 to laminate the metal foil laminate 111 therebetween.

[0053] FIG. 7 illustrates the wrap 100 installed between the foundation of the structure 104 and the ground 105. There is shown the outer protective sheath 103 enclosing the hydrophobic mat 101 therein in direct contact against the foundation. There is also shown the longitudinal narrowing 108 located towards an upper edge of the wrap 100.

[0054] FIG. 8 illustrates the installation and use of the wrap which, with reference to FIG. 4 comprises the step of the installation of the foundation at step 117 and the excavation around the foundation 118 as is illustrated in FIG. 4A.

[0055] Step 119 comprises wrapping the wrap 100 around the foundation and sealing the edges thereof. The wrap 100 is preferably installed un-impregnated with preservative, thereby preventing handling contact therewith. Once installed, the mat 101 may be soaked with preservative.

[0056] Step 120 comprises refilling the excavation, thereby embedding the foundation of the structure 104 with the wrap 100 subsumed therearound.

[0057] The wrap 100 is located such that an upper edge thereof is accessible such that, at step 121, the preservative can be periodically replenished, such as every 5-10 years such that the wrap 100 can be left in place. In embodiments, the preservative may be replenished using an applicator as is disclosed in co-pending patent entitled A chemical applicator system for replenishment of embedded foundation preservation wraps by the present Applicant, the entire contents of which are incorporated herein by reference.

[0058] The foundation of the structure 104 may comprise metal. In this regard, the structure 104 may be entirely metallic such as by being a steel or aluminium utility pole or alternatively comprise metal, such as a steel reinforced concrete structure.

[0059] For the preservation of the metallic structure 104, an oil based metallic soap may be used. By being oil base, the preservative is readily absorbed by the hydrophobic mat 101 and which further repels corrosion causing water electrolyte.

[0060] The metal of the metallic soap is chosen to be more electropositive than the metal of the foundation to be protected. As such, the metallic soap acts as an anodic solution for galvanic exchange the metal of the embedded metallic foundation for the passive cathodic protection thereof.

[0061] Where the foundation comprises steel, a zinc or aluminium metal soap may be employed for being more electropositive than steel. Where the foundation comprises aluminium, the metal soap may comprise zinc, being more electropositive than aluminium.

[0062] FIG. 3 illustrates the galvanic exchange for the passive cathodic protection of a metallic foundation comprising iron/steel. In this embodiment, the metallic soap comprises zinc and there is shown zinc molecules 113 in oil suspension in the mat 101.

[0063] As each zinc molecule contacts the iron, electrons are donated thereto by virtue of zinc being more electropositive such that the link is sacrificed as Zn.sup.2+, thereby preserving the iron foundation by passive cathodic protection.

[0064] For steel reinforced concrete foundations, the oil based metallic soap may seep someway through the concrete, thereby also preserving the internal steel reinforcement by passive cathodic protection.

[0065] In a preferred embodiment, the metallic soap is a metal naphthenate thereby conferring wood preservative, insecticidal, fungicidal and acaricidal properties such that the impregnated wrap 100 can be used alternatively for the preservation of wooden foundations such as of wooden telegraph poles or foundations comprising both metal and organic content, such as reinforced concrete comprising steel reinforcement and mixed with organic fibres.

[0066] As such, for the preservation of steel containing foundations, aluminium naphthenate or zinc naphthenate may be employed, both being more electropositive than steel for the passive cathodic protection thereof yet also conferring biocidal properties.

[0067] Whereas the biocidal toxicity of zinc naphthenate may be less than that of copper naphthenate for example, the zinc molecules of the zinc naphthenate may also offer oligodynamic effect. Furthermore, the protective outer sheath 103 may comprise the copper foil laminate 111 for enhanced oligodynamic effect, including for the preservation of the plastic of the outer protective sheet 103.

[0068] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practise the invention. Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed as obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.