Insulating material, method for inspecting the weld and control system for quality control of the weld

Abstract

An insulating material for a waterproofing system having first and second insulating elements joined by melting or welding to form a connecting joint. The insulating material being provided on at least one side with a combustible or thermally destructible and electrically conductive element. Also, a method of inspecting the connecting joint and a control system for controlling the quality of the connecting joint.

Claims

1. A composite comprising: (a) a strip comprising an insulating material that is electrically non-conductive, the strip comprising opposed first and second sides, each of the first and second sides having opposed first and second ends; and (b) a film comprising a combustible or thermally destructible and electrically conductive material disposed on at least the first side of the strip and on at least a portion of the first end of the first side, the thermally destructible and electrically conductive material being combustible or thermally destructible under conditions of fusion or welding of the strip such that, when the first end of the first side of the strip with the film disposed thereon is fused or welded to an end of a second insulating material that is electrically non-conductive to form a connecting joint, the connecting joint will not be electrically conductive unless at least a remnant of the combustible or thermally destructible element is not destroyed in the fusing or welding, the remnant being detectable to show that an imperfection is present in the connecting joint.

2. The composite according to claim 1, wherein the combustible or thermally destructible material comprises a metal foil or a metal fiber.

3. The composite according to claim 1, wherein the film has a thickness of 2 to 15 microns, wherein the film comprises a metal layer comprising a metal foil or electrically conductive fibers.

4. The composite according to claim 3, wherein the metal layer is a discontinuous layer comprising at least two strips of metal film each having a thickness of 1 to 5 microns.

5. The composite according to claim 1, wherein the film is attached to the strip electrostatically, by gluing or by an adhesive layer.

6. The composite according to claim 1, wherein the film is selected from the group consisting of: (i) a film having an inner layer comprising polyethylene and a metal layer comprising aluminum; (ii) a film having an inner layer comprising pressed polyester admixed with conductive fibers; (iii) a film having an inner layer comprising softened polyvinyl chloride admixed with molded electrically conductive fibers; and (iv) a film having a layer comprising polyethylene terephthalate and a conductive metal layer.

7. The composite according to claim 1, wherein the film extends over an entirety of the first side of the strip.

8. A kit comprising (a) The composite according to claim 7; and (b) a device for measuring electrical impedance, electrical capacity to detect a presence in the connecting joint of the remnant.

9. The composite according to claim 1, wherein the film comprises a continuous or discontinuous elongate piece at an edge of the strip or up to 10 cm from the edge of the strip.

10. A kit comprising (a) the composite according to claim 1; and (b) a device for measuring electrical impedance, electrical capacity to detect a presence in the connecting joint of the remnant.

11. A kit comprising (a) a composite consisting of (i) a first element comprising an insulating material that is not electrically conductive, the first element being provided with a thermally destructible or combustible film on at least one surface of the first element, the thermally destructible or combustible film being electrically conductive unless it has been fully combusted or destructed in which case it would not be electrically conductive; and (ii) a second element comprising an material that is not electrically conductive; the first and second insulating elements being joined together only at respective first ends thereof by welding or melting-down with the thermally destructible or combustible film disposed therebetween to form a connecting joint, respective second ends of the first and second elements being spaced from the connecting joint; and (b) a device for determining if the connecting joint is electrically conductive by measuring electrical impedance, electrical capacity electrical variables to detect whether the insulating material comprises combustible film that has not been fully combusted or destructed.

12. The kit according to claim 11, wherein the combustible or thermally destructible element extends over an entirety of the surface of the first insulating element.

13. A composite formed by fusing or welding a first element comprising an insulating material that is not electrically conductive and a second element comprising an insulating material that is not electrically conductive to form fused first and second elements joined in a connecting joint, wherein the first element comprises a combustible or thermally destructible element disposed on at least a portion of at least one surface of the first element, the combustible or thermally destructible element being electrically conductive and being combustible or thermally destructible under conditions of fusion or welding, wherein the fused first and second elements overlap one another only in the connecting joint with respective first ends of the fused first and second elements disposed in the connecting joint and respective second ends of the fused first and second elements spaced from the connecting joint, the connecting joint comprising at least a remnant of the combustible or thermally destructible element not destroyed in the fusing or welding, the remnant being disposed in the connecting joint between the overlapping first ends of the fused first and second elements such that an imperfection in the connecting joint can be detected by testing the connecting joint for presence of the remnant.

14. The composite according to claim 13, wherein the first element comprises the combustible or thermally destructible element on an entirety of the at least one surface of the first insulating element.

15. A method comprising the steps of: (a) providing first and second insulating elements, the first insulating element comprising a first layer of insulating material and a second layer comprising a combustible or thermally destructible element disposed on at least an end portion of at least one surface of the first layer of insulating material, the combustible or thermally destructible element being electrically conductive and being combustible or thermally destructible under conditions of fusion or welding; (b) melting down or welding respective first ends of the first and second insulating elements to form fused first and second insulating elements joined in a connecting joint, wherein the fused first and second insulating elements overlap one another only in the connecting joint with respective first ends of the fused first and second insulating elements disposed in the connecting joint and respective second ends of the fused first and second insulating elements spaced from the connecting joint, the connecting joint comprising at least a remnant of the combustible or thermally destructible element not destroyed in the fusing or welding, the remnant being disposed in the connecting joint between the overlapping first ends of the fused first and second insulating elements such that an imperfection in the connecting joint can be detected by testing the connecting joint for presence of the remnant; and (c) testing the connecting joint to determine whether the remnant of the combustible or thermally destructible element is present in the connecting joint.

16. The method according to claim 15, wherein the second layer of the first insulating element provided in step (a) comprises the combustible or thermally destructible element on an entirety of the at least one surface of the first layer of insulating material.

17. The method according to claim 16, wherein a portion of the combustible or thermally destructible element that is not disposed in the connecting joint is fused to a surface of another substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment of the invention is shown schematically in the accompanying drawings, wherein

(2) FIG. 1 shows the connection of two asphalt strips, wherein the lower asphalt strip is in the mutual overlap provided with the combustible and electrically conductive local film,

(3) FIG. 2 shows the connection of two asphalt strips, wherein the upper asphalt strip is provided with a combustible and electrically conductive local film, and

(4) FIG. 3 illustrates the joining of the asphalt strips to the substrate where a full-area inspection is required and at least one of the asphalt strips is provided with a fully combustible and electrically conductive film.

(5) FIG 4 shows a possible configuration of the combustible and electrically conductive film shown in FIGS. 1, 2 or 3; and

(6) FIG. 5 shows a control system comprising a connecting joint formed between the two asphalt strips of FIG. 1 and a device for measuring an electrical impedance or electrical capacity of the connecting joint.

DETAILED DESCRIPTION OF THE INVENTION

(7) The object of the present invention is to provide an insulating element, most commonly a waterproofing strip, at the points where the strips should be joined or where they are to adhere to the substrate, and it is assumed that these are points where the inspection of their joining or adhering by means of the electrically conductive element should be carried out. However, the insulating element can also be a differently shaped insulating element as well as a variety of additional insulating elements, such as roof outlets, passages, grommets and moldings.

(8) The combustible and electrically conductive element may be attached to the insulating element or support layer, for example, electrostatically, by gluing or by means of a self-adhesive layer. It can be implemented in an insulating element, in particular a waterproofing strip, directly in the production of the strip, either over the entire surface of the strip or only in a part thereof, at locations in the welded areas. It can also be implemented in the form of a thin self-adhesive foil at the locations of the specified welds directly at the welding site, usually on site.

(9) The combustibility of the combustible and electrically conductive element is understood so that as combustible is considered to be the element which is destroyed for example by a flame. For destruction is also understood the destruction of this layer, for example, by hot air or a so-called hot wedge, which utilizes the electrical resistance heating of the steel wedges, followed by an integrated pressure roller.

(10) For example, after application of an asphalt strip to the surface, i.e. after laying it and welding by flame or hot air, where the applied temperature must be capable of complete destruction of the combustible film layer including the conductive layer, the quality of welds and local or full-area melting and thus the adhesion to the substrate, are subsequently tested by means of electrical impedance or induction measuring devices which are commonly available.

(11) In the case of high-quality welds or melting-down to the base, the film will be destroyed or liquidated, which film will be technologically replaced by a homogeneous joint. The method according to the invention also detects even the residual amount of the un-welded film and if the film has not been destroyed at the weld site, this means that a poor-quality weld or melting has been carried out at that point and needs to be repaired. The most preferred device is a device for measuring the electrical impedance.

Example 1

(12) In the field of engineering constructions, in particular waterproofing of traffic constructions, bridge decks, tunnels, ditches, reservoirs, dams, dams, leaching areas and reservoirs in mining industry, landfills, water channels, waterproofing of substructures, protection of building structures against ground moisture and water, a bitumen geomembrane or a large-size loose-laid asphalt strip with welded overlaps are advantageously used, where the inspection of welds is generally required.

(13) The waterproofing strip is provided with a combustible and electrically conductive film 4, which consists of an inner layer of polyethylene or polyethylene terephthalate having the thickness 10 microns and a metallic, electrically conductive film, in this case aluminum foil having the thickness 2 microns. In this case, the implementation of the metal foil is carried out directly in the asphalt strip manufacturing plant, but it is also possible to provide this strip with a combustible and electrically conductive element at the construction site, for example by gluing it to the site of the assumed joint design. Locally, it is possible to use a self-adhesive variant of the combustible and electrically conductive film which is applied in details and transversal overlaps either within the production, preparation or on site. The metal foil may also be replaced by another electrically conductive layer, for example by a layer of electrically conductive plastics or an electrically conductive fabric. The combustible metal film can be made discontinuous, that is, it can be made not over the entire surface, but for example in differently spaced strips.

(14) As shown in FIG. 1, it is necessary to join the lower asphalt strip 1 with the upper asphalt strip 2 by overlapping the two asphalt strips by welding. As a rule, the manufacturer himself specifies the minimum weld width 3 for correct and safe welding. At the edge of the lower asphalt strip 1, a combustible and electrically conductive foil 4 is placed.

(15) The location of the combustible and electrically conductive foil 4 relative to the edge of the lower asphalt strip 1 may vary, in particular according to the quality control requirements of the weld performance. The combustible and electrically conductive film 4 may be positioned on the upper face of the lower asphalt strip 1 overlapping across the inner side of the asphalt strip at a distance from its end edge, preferably about 4 cm from the end edge, and includes only a portion of the required minimum weld width 3 as shown in FIG. 1

(16) Another possibility is to place the combustible and electrically conductive film 4 on the upper face of the lower asphalt strip 1 overlapping across the entire width of the required minimum weld width 3, usually also at a distance of about 4 cm from the end edge of the lower asphalt strip 1, taking into account the manufacturer's requirements for a minimum weld joint width.

(17) It is possible to place the combustible and electrically conductive film 4 on the upper face of the lower asphalt strip 1 overlapping over the entire width of the overlap, that is to the end of the edge of the lower asphalt strip 1.

(18) After application of the asphalt strip to the surface and after its welding by flame, where the applied temperature or welding energy is such that the combustion foil including the possible metallized coating is burnt, the quality of welds and full-area melting-down to the substrate including the join homogeneity is subsequently tested by means of the electrical impedance measuring device.

Example 2

(19) A second specific embodiment is based on the previous example number 1, but the location of the combustible and electrically conductive film 4 is provided on the lower face of the upper strip in their mutual overlap, as shown in FIG. 2.

(20) The location of the combustible and electrically conductive film 4 relative to the edge of the upper asphalt strip 2 may vary, in particular according to the quality control requirements of the weld performance. The combustible and electrically conductive film 4 may be disposed on the lower face of the upper asphalt strip 2 overlapping across the inner side of the asphalt strip at a distance from its end edge, preferably about 4 cm from the end edge, and comprises only a portion of the required minimum weld width 3 as shown in FIG. 2.

(21) Another possibility is to place the combustible and electrically conductive foil 4 on the lower face of the upper asphalt strip 2 overlapping across the entire width of the required minimum weld width 3, usually also at a distance of about 4 cm from the end edge of the upper asphalt strip 2.

(22) It is possible to place the combustible and electrically conductive film 4 on the lower face of the upper asphalt strip 2 overlapping across the entire width of the overlap, i.e. to the end of the edge of the upper asphalt strip 2, taking into account the manufacturer's requirements for a minimum width of the welded joint.

Example 3

(23) The third specific embodiment of the present invention is based on the requirement that the subject matter of the inspection be a full-surface melting of the insulating element and a full-surface proper adhesion of the insulating element to the substrate.

(24) This is particularly advantageous for use in civil engineering, especially waterproofing of traffic constructions, i.e. bridge decks and tunnels, locally reservoirs, barrages, dams, landfills, water channels, where melting to the substructure is required, fully-sealable asphalt strips for waterproofing substructures, for protection of building structures against ground moisture and water, fully-fusible asphalt sheets for roof waterproofing, both single-layer and multi-layer systems and the like. This example of the technical solution is schematically illustrated in FIG. 3.

(25) This example differs from the previous examples of the particular embodiment of the invention in that at least one of the insulating elements is provided with a combustible and electrically conductive film over the entire surface of the insulating element.

(26) In the particular case, it is again the lower asphalt strip 1 and the upper asphalt strip 2, which in both cases are provided with a combustible and electrically conductive foil 4 over their entire surface, either on the upper or lower surface. FIG. 3 describes the embodiment, wherein the insulating element, i.e. the lower asphalt strip 2 and the upper asphalt strip 1 are provided with a combustible and electrically conductive film on their lower surface.

(27) As shown in FIG. 4, the combustible and electrically conductive film 4 of the invention can comprise two (2) layers, including an inner layer 5 and a conductive layer 6. For example, layer 5 could comprise polyethylene or pressed polyester fibers with an admixture of long conductive fibers. Alternatively, inner layer 5 could comprise softened polyvinyl chloride with molded electrically conductive fibers. As another alternative, layer 5 could comprise polyethylene terephthalate and layer 6 could be a conductive layer comprising metal such as aluminum.

(28) As shown in FIG. 5, a control system of the invention can comprise a combination of (a) an insulating material comprising asphalt strip 1 welded to asphalt strip 2 with combustible and electrically conductive film 4 being disposed with the confines of, and forming part of, connecting joint 7; and (b) a device 8 for measuring electrical impedance or electrical capacity of any remnant of the combustible and electrically conductive film that is not destroyed in forming the weld.

INDUSTRIAL APPLICABILITY

(29) The invention can be used for all kinds of insulating elements, in particular for waterproofing asphalt strips, where the essential aspect for carrying out the insulating works is the need to demonstrably detect the perfect connection of the individual strips of insulation or the perfect adhesion of the insulating element to the substrate.

LIST OF REFERENCE NUMERALS

(30) 1lower asphalt strip 2upper asphalt strip 3minimum weld width 4combustible and electrically conductive film