AU2001100343A4 - Joint sealing system - Google Patents

Description

P/00/012 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: "JOINT SEALING SYSTEM" The following statement is a full description of this invention, including the best method of performing it known to me/us: H:.WORKRTKI8257AU3 ipa innovationfilhng.doc 2

TITLE

"JOINT SEALING SYSTEM" FIELD OF THE INVENTION THIS INVENTION relates to a joint sealing system.

BACKGROUND OF THE INVENTION Conventional sealing systems for joints are well known and one particular sealing system in use is marketed under the SIKADUR-COMBIFLEX trade mark. This sealing system comprises principally two components, i.e. an epoxy resin based adhesive and a resilient tape or strip having a thickness of 2-3 mm or thicker made from elastomer or synthetic rubber, which was usually marketed under the trade mark HYPALON. This elastomer was made by substitution of chlorine and sulfonyl chloride into polyethylene and usually required application of an activator or curing agent before use.

Such conventional sealing systems can be applied to dry or damp substrates, which were formed from concrete, iron, steel or timber. The sealing system would be applied to internal joints in new or refurbished concrete water tanks, reservoirs, pipelines, aquariums, sewers and swimming pools as well as sealing underwater joints in situ, large decks of multi-storey carparks, tunnels, silos, roofs as well as expansion joints that have more movement than can be accommodated by conventional elastomeric wet applied sealants.

In use, the SIKADUR-COMBIFLEX sealing system was applied as shown in FIG. 1 herein and this is described in detail hereinafter.

3 In use, the aforementioned conventional sealing systems were found to be satisfactory in a number of situations but were subject to the following disadvantages:use of the HYPALON tape along an elongate joint was not endless and thus there were overlapping sections forming joints of the tape at spaced intervals along the length of the tape. These overlapping joints were connected usually by heat welding and provided areas of structural weakness; the conventional sealing systems as described above were found to be expensive and time consuming in installation because of the use of an initial coat of adhesive followed by HYPALON tape and a final coat of adhesive; use of a sandwich type joint involving bottom coat and top coat of adhesive separated by HYPALON tape did not provide complete bonding integrity; and the conventional sealing systems had different installation procedures, which were dependent on the width of gap or joint aperture, and thus a standardized versatile sealing system was not provided.

Reference may be made to FR 2454341, which refers to an expansion joint for suspended roof slabs, which accommodates the relative thermal movement of two suspended slabs separated by the expansion joint. A central zone of the expansion joint is debonded by application of a debonding layer, which is covered by hot poured elastomeric rubber-bitumen mixture. At each end of the elastomeric rubber-bitumen mixture, there is provided an angle iron reinforcement to confine the in situ hot poured layer of elastomeric material.

This prior art reference refers to an example of a non seamless joint wherein by virtue of hot pouring of the elastomeric mixture the angle iron reinforcements are necessary at each end of the elastomeric mixture to maintain the stability of the joint. Thus the resulting joint is a non seamless joint, which experiences stress as soon as a load is applied.

SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a joint sealing system, which is seamless or not subject to overlapping joints or sections as described and which is simple and effective in use.

The method of the invention includes the following steps:application of a debonding material suitably in strip form to a joint having a joint aperture wherein the debonding material is applied to each side of the joint or aperture and/or within or over the joint aperture; and (ii) application of an elastomer by spray, brush or roller to the debonding material which debonding material is maintained permanently within the joint being sealed and covered by a layer of elastomer which extends to each side of the joint aperture to provide an external seamless covering.

The invention also provides a sealing system for gaps, which comprises an initial application of debonding material, which is retained within the gap by a subsequent seamless coat of elastomer.

Preferably in relation to the process of the invention, the joint surface was usually cleaned mechanically and was then primed by application of a suitable primer. Such a primer may be selected from water based acrylics, solvent bases, silanes, cementitious epoxy resins, epoxy resins, isocyanates, PVC, styrene-butadiene resins or polyvinylacetate coatings.

Subsequently the debonding material is applied to the joint. The debonding material is preferably flexible and is usually in the form of a strip or tape, such as masking tape, duct tape or electrical tape. Preferably the debonding tape is in the form of an adhesive tape having one broad surface which had an adhesive applied thereto. The tape may be formed from any suitable plastics material or could be formed from fabric inclusive of linen or cotton or even metal in some cases. It is, however, useful to use a tape, which is inert to the coat of elastomer and does not restrict elongation or flexing of the elastomer in use. The debonding tape may also be formed from non-woven or woven fabric, geotextile material, material from low density or high density polyethylene or even paper or cardboard in appropriate circumstances. The debonding material functions to space or separate the final elastomer coat from the joint surface(s) and/or gap aperture.

In some cases, a filler cord may be applied to the joint before application of the debonding agent. The filler cord may be formed from compressible or resilient material, such as extruded polystyrene, polystyrene foam, rubber, rubber composites, polysulphate or polyurethane material.

Alternatively, a filler rod made of rigid material could be utilised. Such rigid material could be metal or plastic material. The use of the filler cord is appropriate when it is desired to provide the debonding tape with a hump or concave shape as hereinafter described.

6 In other situations, the filler cord may be omitted and the debonding tape may be applied to the joint so that the debonding tape forms a U-shape or trough shape within the gap aperture.

Finally, an elastomer is applied to the joint and this may comprise any suitable elastomer which may be formed from a synthetic elastomer which may comprise polyurea, polyurethane, epoxy resins, bituminous compounds, polyvinyl chloride, rubber including synthetic rubber as well as natural rubber and thermoplastic elastomers. Acrylic elastomers, butyl rubber, chlorosulfonate polyethylene, ethylene-propylene rubber, fluorinated elastomers, neoprene, nitrite rubber, polybutadiene, polyethers, polyisoprene, SBRs or polypentenamers may be utilized and especially those that are susceptible for spray on application. However, it will be appreciated that the elastomer may also be applied to the debonding material by brush, roller or other suitable means.

In another variation, the elastomer may be pre-applied to the debonding material prior to application to the joint and this is described in detail hereinafter.

A particularly preferred elastomer is a polyurea elastomer marketed under the trade mark ENVIROLASTIC, which is marketed by EnviroChem Technologies, Forth Worth, Texas, U.S.A. The specification for this material describes it as "based on proprietary urethane polymers and an amine type curing mechanism". It has high strength and high impact and abrasion resistance and is seamless and flexible. It may be applied to concrete or metal substrates.

7 The joint sealing system of the invention may be applied to joints or gaps in tunnels, pipes, pits, floors, walls, ceilings, tanks, reservoirs, basins, aqueducts, roofs, culverts and internal or external surfaces of buildings. The sealing system of the invention may also be applied to timber, geotextile fabrics, metals, plastics and any other type of surface.

BRIEF DESCRIPTION OF THE DRAWINGS Reference may now be made to a preferred embodiment as shown in the drawings, wherein:- FIGS. 1A, 1B, 1C, ID, 1E, 1F and 1G are schematic drawings showing the various steps applicable to application of a prior art joint sealing system described herein; FIGS. 2A, 2B, 2C, 2D and 2E are similar views to FIGS. 1A-1G showing the various steps applicable to one embodiment of a joint sealing system of the invention; FIGS. 3A, 3B, 3C, 3D, 3E, 3F and 3G are similar views to FIGS.

2A-2E showing the various steps applicable to another embodiment of the joint sealing system of the invention; FIG. 4 is a cross section of a raised joint using a filler cord; FIG. 5 is a cross section of one type of recessed joint wherein a filler cord is omitted; FIG. 6 is a cross section of another type of recessed joint to which the sealing system of the invention has been applied; FIG. 7 is a cross section of a joint located at the junction of a floor and wall, which has been sealed in accordance with the invention; 8 FIG. 8 is a similar view to FIG. 7 showing another type of joint located at the junction of a floor and wall, which has been sealed in accordance with the invention; FIG. 9 is a view similar to FIG. 8 showing a different embodiment of the invention; FIG. 10 is a view similar to FIG. 8 showing a different embodiment of the invention; and FIG. 11 is a view similar to FIG. 8 showing a different embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS In FIG. 1, the prior art method refers to application of the conventional sealing system described herein under the SIDADUR- COMBIFLEX trade mark, which is applied to joint 10 having a gap 7, which is bounded by top surfaces 11 and 12 of concrete walls 8. After surface cleaning and priming, a base coat 9 of adhesive is then painted or otherwise applied to each top surface 11 and 12 after application of primer 6. The adhesive utilized in the prior art method was not an elastomer and, in fact, comprised an epoxy resin, which was noted for its adhesive or bonding ability as well as high chemical resistance properties.

Subsequently a debonding material was applied to the adhesive usually on one side only of the joint aperture 7. However, it was to be appreciated that the masking tape could also be applied to both sides of gap 7 or over gap 7. This debonding material was masking tape 14. In some cases, at the preference of the contractor, the masking tape 14 could be applied prior to 9 application of base coat adhesive 9 and was then removed after application of base coat 9. In other circumstances, the masking tape 14 was applied after application of base coat 9. Usually a filler cord 15 was applied to gap 7 prior to masking tape 14 although the filler cord could be omitted if it was desired to provide a depressed U-shaped joint.

Thereafter, a membrane in the form of HYPALON tape 16 was applied across gap 7 as shown after removal of masking tape 14. This membrane then cured within a period at least one hour after application of curing agent. The HYPALON tape 16 has a median strip 17 and edge apertures 18 which facilitate attachment to surfaces 11 and 12 by adhesive 9 extruding through apertures 18 and forming a series of spaced "pin locks".

Subsequently a top coat 19 of adhesive is applied to the surfaces 11 and 12 on top of tape 16 and thereafter median strip 17 was removed before setting of top coat 19.

From the foregoing, it will be appreciated that the prior art method shown in FIGS. 1A-1G required the application of an initial coat or base coat of non-elastomeric epoxy resin or adhesive as well as a final coat 19 of nonelastomeric epoxy resin. Any debonding material was removed from the joint prior to application of HYPALON tape 16 which required at least one hour to cure after application of curing agent.

In contrast, the method of the invention as shown in FIGS. 2A-2E after cleaning and priming of surfaces 11 and 12 comprises application of debonding material 20 across gap 7 although in some cases it may only be necessary to apply debonding material to surfaces 11 and 12 leaving gap 7 clear. A filler cord 15 may also be used if it is desired to have an elevated or raised joint. Finally, a coat of elastomer 21 is applied to joint 10 suitably by spraying by spray gun 22.

It therefore will be appreciated that the method of the invention is much simpler than the prior art method in not requiring the use of base and top coats of non-elastomeric adhesive nor the use of HYPALON tape 16 which requires at least one hour of curing agent. The sealing method of the invention can be universally applied to apertures of any size and is not dependent upon the width of gap 7. The sealing method of the invention also provides a seamless finish not having any welded joints. It is also relevant that in the prior art method shown in FIGS. 1A-1G the debonding material is removed wherein in the method of the invention, the debonding material is retained permanently within the finished joint.

In FIG. 3, there is shown another embodiment similar to the FIG. 2 embodiment, with the exception that steps shown in FIGS 2D and 2E are varied by the steps shown in FIGS. 3D-3G. In FIG. 3D a layer 20A of adhesive or bonding agent is applied to surfaces 11 and 12 prior to application of a debonding membrane 20B, which has had a layer 21 of elastomer applied thereto prior to application to surfaces 11 and 12. Then in FIG. 3F, a final layer of elastomer 20D is applied, preferably by brush or roller, on each side of membrane FIG. 3G shows a cross sectional view of what is illustrated in FIG.

11 The debonding membrane 20B may be formed of any suitable debonding material, as described above, inclusive of fabric, geotextile material and plastics material. Conventional masking tape may also be used.

As shown in FIG. 4, the joint 10A of the invention has elastomer 21 applied over debonding layer 20, which covers filler cord 15. This is an example of an elevated joint as opposed to a depressed joint 10B shown in FIG.

wherein filler cord 15 is omitted and debonding material 20 is applied to gap 7 layer 20A) as well as being applied to surfaces 11 and 12.

In some cases, a steel plate may extend across joints sealed in accordance with the invention, such as joint 10C in FIG. 6 wherein steel plate 22A is attached to top surface 27 of joint 10C by fasteners 28. Also, when appropriate, it may be useful to apply over joint 10C a layer of polyethylene foam 23.

FIG. 7 shows application of joint 10D to a wall to floor joint wherein wall 8A is located adjacent floor 8B.

FIG. 8 also shows application of joint 10E to a wall to floor joint, wherein there is used a filler cord 15 to provide a raised joint. Filler cord 15 is round in cross section. However, filler cord 15 may also be quadrant shaped in cross section as shown in FIG. 9, triangular in cross section as shown in FIG.

10 or square in cross section as shown in FIG. 11. Fig. 9, 10 and 11 show joints 10F, 10G and Having regard to the preferred embodiment of the invention as shown in the drawings, it is noted that debonding material 20 or debonding membrane 20B not only spaces elastomer 21 from surfaces 11 and 12 but also 12 provides a firm support for the elastomer 21 and allows the elastomer 21 to flex as may be required when external forces are applied to the joint 10. It will also be appreciated from the drawings that elastomer 21 also bonds securely to surfaces 11 and 12 on either side of the joint 10 to provide a joint with substantial bonding integrity.

It will also be appreciated that the joint sealing system of the invention may be applied to gaps of between 1 mm up to 300mm.

It will also be appreciated that in another variation of the invention there may be applied a kit comprising membrane 20B which already has elastomer 21 applied thereto, primer, adhesive and elastomer as a final coat.

The kit may also include filler cord 15 when an elevated joint is required.

DATED this Seventh Day of September 2001.

WILLIAM CLAUDIO BONA, by his Patent Attorneys, FISHER ADAMS KELLY.

Claims (4)

1. A method of sealing a joint, which includes the following steps: application of a debonding material suitably in strip form to the joint which has a joint aperture wherein the debonding material is applied to each side of the joint aperture and/or within or over the joint aperture; and (ii) application of an elastomer by spray, brush or roller to the debonding material which debonding material is maintained permanently within the joint being sealed and covered by a layer of elastomer which extends to each side of the joint aperture to provide an external seamless covering.

2. A method as claimed in claim 1, wherein in step (i) debonding material is applied to the joint only on both sides of the joint aperture.

3. A method as claimed in claim 1, wherein in step (i) debonding material is applied to the joint above or over the joint aperture.

4. A joint sealed by the method of any one of the preceding claims. A joint having a joint aperture and having a layer of debonding material applied thereto, which is covered by a coating of elastomer applied to each side of the joint aperture characterised in that said coating of elastomer: contacts a top surface of each side; and (ii) is seamless in nature.