GB2223759A

GB2223759A - Bitumen-rubber-metal fibre or wire based compositions and their use in repairing or surfacing roads

Info

Publication number: GB2223759A
Application number: GB8820329A
Authority: GB
Inventors: James Mcintosh; Ronald James Goodenough
Original assignee: FIBREDEC Ltd
Current assignee: FIBREDEC Ltd
Priority date: 1988-08-26
Filing date: 1988-08-26
Publication date: 1990-04-18
Also published as: GB2222168A; GB8820329D0; GB2222168B; GB8830290D0

Abstract

A material for repairing roads and other areas comprises (1) a bitumenous binder, usually rubberised bitumen, which may be mixed with aggregate and chopped glass or other fibres, (2) rubber chips, bound by the binder, and comprising pieces of rubber having a dimension of at least 2 mm, and (3) metal wire or fibre. Suitably the rubber chips and metal reinforcement may be obtained by chopping up old metal reinforced vehicle tyres. The material may be used for patching cracked areas for subsequent treatment with an overlay, the resilient rubberised bitumen being bad bearing and having sufficient tensile strength that reflective cracks are not transmitted to the overlay from underlying concrete having a large coefficient of thermal expansion. Also, the material may be used as a membrane layer covering a base layer or surface. Such a layer may be formed by spreading the binder, possibly also with the addition of strengthening glass fibres, distributing the rubber chips and metal over the binder, and rolling to consolidate.

Description

--- -1 i 2 'el- 22 3 7 5 9 -1IMPROVED MATERIAL FOR USE IN, AND METHOD OF,

REPAIRING OR SURFACING ROADS AND THE LIKE This invention relates to an improved material and process using this material to repair or surface roads, parking areas, aircraft pavements and other load bearing areas. For example, the method may be applied to aircraft pavements, roads, paths, motorways and footpaths.

The present invention is particularly concerned with providing repairs using a material which has some degree of resilience and which has a tensile strength and is thus especially useful where the surface to be repaireJ is jointed or cracked or spalled. This is particularly useful where one is endeavouring to repair concrete surfaces or surfaces with a concrete underlay in that the concrete expands and contracts greatly with changes of temperature and if one uses a conventional road surfacing material this is brittle and the movement of the concrete tends to provide reflective cracks from the joints or cracks in the concrete to the surface of the black top, Macadam or other conventional surfacing material. Thus, frequently with old concrete surfaces which have been laid in concrete with expansion joints between adjacent concrete areas, not only do the joints themselves cause difficulty but after a period of use the edges of the joints frequently will crack and one can end up with a substantial degree of cracking or enlargements of the joints and spalling of the concrete, that is the provision of 1 localised crack holes and hollows in the concrete, which, if filled with conventional materials will permit the ready transference of cracks to the applied surfacing material after a relatively small period of use.

The present invention is concerned with the provision of a material which uses rubber to give the necessary resilience, which may have aggregate included to provide load bearing resistance and which also includes material to provide a tensile strength.

Thus, in accordance with one aspect of the present invention, there is provided a material for use in repairing or servicing roads, parking areas, aircraft pavements and other load bearing areas, such material comprising rubber chips having a maximum dimension of at least 2 mm and mixed therewith lengths of metal fibre or wire longer than the maximum dimension of the chips, said rubber chips and lengths of metal fibre or wire being bound together with a bitumenous binder.

Generally, when referring herein to rubber chips we are concerned with rubber in the form of pieces having a maximum dimension greater than 2 mm, preferably in the range of 3 to 7 mm, conveniently about 5 mm. Generally, also, the metal fibre or wire is very fine and is chopped to have a length greater than the rubber chip dimensions.

A further aspect of the invention provides a method of repairing or surfacing roads, parking areas and other load bearing areas in which the hot material of the t -3invention is applied to the area. In most cases aggregate is mixed with the bitumenous binder, which itself may be rubberised bitumen, and chopped glass or other fibres may in some circumstances also be mixed therewith although not normally required.

Where one is using the material of the present invention to repair localised areas of joints or cracking or spalling, the aggregate may be included up.to as much as 25 mm in maximum dimension although preferably it will be from 3 to 5 mm in maximum dimension to ease application, especially where the depth of application in some areas is quite small. Once the sites of movement, for example expansion joints and cracks, have been covered with the material, possibly strengthened with aggregate, and reinforced with the metal fibre or wire a covering overlay may be applied to render the area fit-for use. Typically, this overlay may be of glass fibre strengthened bitumen with a surface dressing as disclosed in our British Patent No 2 081 603. Alternatively, a conventi onal black top or Macadam surface may be applied to a thickness 30 mm, more usually in excess of 50 mm, frequently as much as 100 or 200 mm. Other alternative surface overlays or dressings which may be used include veneer surfacings of 3 mm upwards in thickness.

Where one is using the material of the invention with the inclusion of aggregate to cover a surface area, the aggregate should have a maximum dimension of 5 mm, -4preferably approximately 3 mm, and generally no larger than the dimensions of the rubber chips in the material. Such a layer would be particularly suitable for spreading on more lightly loaded paths and the like, where the underlying surface may be crazed or lightly cracked or which has had more badly damaged areas already repaired and filled otherwise, for example with the material of the invention which contains a greater proportion of rubber in the bitumen and possibly larger sized aggregate.

The material of the invention may be mixed on site or may be supplied ready mixed for subsequent melting down and laying.

We will describe, by way of example, the use of material of the present invention for repairing joints and cracked or spalled surfaces or providing thin patches to badly worn localised areas. In doing this, the material may typically comprise approximately 50% of rubberised bitumen binder material. The rubberised bitumen binder will have added to it 5 to 50% by weight rubber chips and metal fibre or wire which has been formed by the coarse chopping of vehicle tyres. By chopping metal reinforced tyres an appropriate proportion of metal reinforcement wire or fibre is provided for the mix. During this chopping of the tyres the metal reinforcing strands in the tyre become untwisted and unravelled and are chopped but, because of their flexibility and fineness, the individual lengths of wire are left with a length several times the dimension of -5the rubber chips. For use in patching purposes one would expect at least 10%, preferably 15%, rubber in the rubberised bitumen. The aggregate could have a maximum dimension of preferably 3 to 5 mm although, depending upon the circumstances, a greater maximum dimension could be used, for example even as much as 20 to 25 mm. Where additional fibre, preferably glass, is added to the mixture it would not normally be more than 5% and in most cases 0.5 to 1.5%, say 1%, is adequate, in those unusual situations where tensile strength additional to that provided by the metal is required. The hot mixture is applied to the cracks or other surface areas requiring substantial repair and when set the additional covering surface is applied as required. Thus, as indicated previously, this additional surface may, for example, be a glass fibre reinforced bitumen provided with a dressing or a conventional black top Macadam surface. The resilience of the rubber chips in the bitumen with the tensile strength provided by the chopped metal fibre or wire prevents reflective cracks passing from the underlaying repaired surface to the top surface of the overlay and the substantial aggregate content of the material enables it to be load bearing and resistant to subsidence when passed over by heavy vehicles. A relatively thin layer of this material may be applied over localised areas for patching purposes as a membrane subsequently to be covered by an overlay.

Generally, above, we have been referring to the use of a material comprising the rubber chips and metal fibres mixed therein for localised patching purposes, normally prior to subsequent covering with a traffic bearing overlay surface. However, the present invention can also be used to provide an overall layer or membrane over an entire base area with that membrane layer including the rubber chips and the fine metal fibre or wire reinforcement. This can be achieved simply by spreading a layer of rubberised bitumen or rubberised polymer modified bitumen over the area, the rubberised bitumen preferably, although not necessarily, including a fine aggregate or sand filler. The rubber chips and metal reinforcement can either be mixed in that rubberised bitumenous layer prior to application of the material or may be distributed over the material after it has been laid and then rolled and compressed so as to become embedded in that material in the same manner that in a more conventional road surfacing aggregate would be spread over and compressed into an underlying binding layer. One disadvantage of using rubberised bitumen as the binder material, although adding to the resilience and quantity of rubber in the layer, is that it cannot be applied easily by spraying. Thus, in an alternative method utilising the invention a less viscous, more liquid, bitumen emulsion or polymer modified bitumen emulsion may be sprayed over the surface prior to having the rubber chips and metal reinforcement distributed -7thereover for rolling in position. Aggregate may also be applied or included in the distributed bitumenous binder as required but normally in this situation would not have a dimension greater than that of the rubber chips and preferably would have a very much smaller dimension, more commonly being in the form of a fine grained aggregate or sand filler to the binder.

One particularly preferred method comprises distributing a layer of bitumenous binder with the addition of chopped glass fibre or other fibres and then distributing the rubber chips and metal reinforcement over that layer prior to rolling it in to cause it to be bound into a continuous rubberised layer. A further traffic bearing overlay can then be provided over the area to which the membrane has been applied.

A membrane layer as referred to above is particularly useful for applying as a thin repair layer to such surfaces as lightly loaded paths or other walk-on areas which are infrequently used by vehicles although even so the resilience of the rubber of the layer will give a resistance to cracking in conjunction with the tensile strength added by the included fibres of metal and possibly also of glass or the like.

In generalr in most applications, the proportion of aggregate in the material may be from 40 to 60% although proportions outside this range may be used, depending upon the particular application and the amount of fine grained -8filler, if any, in the rubberised bitumen. Preferably, the proportion of aggregate in the material is approximately 50% by weight. However, in other applications no aggregate at all may be used. Thus a sandwich construction may be provided in which the sandwich "filling" comprises a membrane or layer of bitumen containing the chopped rubber pieces and metal fibre or wire. This "filling" may, or may not, contain aggregate depending upon the degree of resilience required, and provides for good non-cracking load transfer from an overlying top layer to the underlying support or base surface.

In all these applications, we have referred glass fibres as being used when applied additionally metal fibres or wire. Usefully, the glass fibres may chopped to a length of approximately 30 mm. While we referred herein generally to the use of glass fibres, will be appreciated that other materials may be used, to to the be have it for example polyamide or other metal fibres, although presently glass fibres are the preferred additional tensile- strengthimparting material when such is required.

Various advantages accrue from the use of the substantial sized pieces of rubber in the material of the present invention in conjunction with the longer lengths of fibre metal wire or fibre. Surprisingly, better wear resistance appears to be obtained than when using the simple conventional rubberised bitumen having a far smaller rubber particle size and also the incorporation of the -gmetal wire provides very good tensile strength properties despite the relatively small proportion of metal wire present. While in some extreme cases it may be desirable to add additional longer fibres to increase tensile strength, in general it has been found that the use of the metal fibres or wires is very adequate and gives a better result than previous structure of the applicants as disclosed in GB-2 200 645-A where smaller rubber particle sizes are used with the longer glass or other fibres providing the tensile strength. Indeed, where extreme resilience is required, the present invention can use the bitumen and rubber with the chopped wire reinforcement with very little if any aggregate addition in order to provide a resilient waterproof membrane of substantial thickness between different layers of a road or other load bearing surface.

A particular advantage of the present material is that it can very readily be made simply by chopping up old wire reinforced vehicle tyres. Thus, modern radial tyres contain a substantial amount of metal reinforcement which conventionally is very difficult to separate reliably from the rubber in order to use the rubber for_ other purposes, for example broken down to a small parti-cle-sized crumb for use in conventional rubberised bitumen. -The material of the present invention requires far less breaking down of the tyres in view of the relatively large rubber chip size. The inclusion of the metal of the tyre reinforcement -10randomly bound to or, more usually, separated from the rubber chips provides what appears to be an ideal road construction material where it is important to prevent the transmission of reflective cracks. Thus, during the chopping up of the rubber tyres the twisted tensile cables are chopped and rapidly unravelled to the very fine and flexible constituents of the cable. Due to this fineness and flexibility most of the metal is not chopped as short as the dimensions of the rubber chips such that when the rubber is formed in 2 mm dimension chips the pieces of wire will normally have a length of from 20 to 30 mm; however due to the random nature of the chopping some of the metal lengths will be shorter, similar in length to the rubber chip dimensions or even shorter.

Claims

-11C L A I M S

1. A material for use in repairing or servicing roads, parking areas, aircraft pavements and other load bearing areas, such material comprising rubber chips having a maximum dimension of at least 2 mm and mixed therewith lengths of metal fibre or wire longer than the maximum dimension of the chips, said rubber chips and lengths of metal fibre or wire being bound together with a bitumenous binder.

2. A material according to claim 1, wherein the rubber chips are bound together with rubberised bitumen or a bitumen emulsion as the bitumenous binder.

3. A material according to claim 2, wherein the bitumen of the emulsion or of the rubberised bitumen is a polymer modified bitumen.

4. A material according to claim 2 or 3, wherein the bitumenous binder is rubberised bitumen material which includes 5 to 25% rubber.

5. A material according to any preceding claim, wherein the bitumenous binder has aggregate mixed therewith, the aggregate being no larger than 25 mm in maximum dimension.

6. A material according to claim 5, wherein the aggregate is no larger than 5 mm in maximum dimension.

7. A material according to claim 5p wherein the aggregate has a maximum size in the range of 3 to 7 mm and has dimensions similar to that of the rubber chips.

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8. A material according to any preceding claim, wherein the metal fibers are approximately 20 to 30 mm long.

9. A material according to any preceding claim, which also comprises up to 5% by weight of glass or other f ibres.

10. A material according to claim 9, which comprises from 0.5 to 1.5% by weight glass fibre.

11. A material according to any preceding claim, wherein the rubber chips have their maximum dimensions in the range of 3 to 7 mm, preferably about 5 mm.

12. A method of repairing or surfacing roads, parking areas, aircraft pavements and other load bearing areas in which a hot material is applied to the area, such material being as claimed in any preceding claim.

13. A method according to claim 12, wherein the material is applied to localised damaged portions only of the area.

14. A method according to claim 12, wherein the material is applied as a continuous membrane layer over the whole area.

15. A method according to claim 13 or 14, wherein the area has sequentially applied to it a covering traffic bearing overlay.

16. A method of repairing or surfacing roads, parking areas, aircraft pavements and other load bearing areas wherein a material comprising a mixture of rubberised 11 - -13bitumen, rubber chips and metal fibre or wire is applied hot to localised cracked, chipped and/or joint areas and a further surface layer is applied over the area to be repaired, including both said localised areas and the remainder of the area to which said material has not been applied.

17. A method according to claim 16, wherein the applied material includes aggregate.

18. A method of repairing or surfacing roads, parking areas, aircraft pavements and other load bearing areas wherein a continuous layer is applied over the area to be repaired or surface, said layer comprising rubber chips and metal fibre or wire bound together by bitumenous binder material.

19. A method according to claim 18, wherein a further traffic bearing surface layer is applied over said continuous layer.

20. A method according to claim 18 or 19, wherein said continuous layer is applied as a mixture of said bitumenous binder material, rubber chips and metal fibre or wire.

21. A method according to claim 18 or 19, wherein said continuous layer is applied by spreading a layer of the bitumenous binder material over said area, distributing a mixture of rubber chips and metal fibre or wire over the binder material and rolling the chips and metal into the binder material to be bound thereby.

(1

22. A method according to claim 21, wherein the aggregate is added by being distributed over the bitumenous binder material and rolled thereinto together with the rubber chips and metal.

23. A method according to claim 21 or 22, wherein the bitumenous binder material itself has rubber chips and metal fibre or wire mixed therein before application to the area.

24. A method according to claim 20, 21, 22 or 23, wherein the bitumenous binder material contains an aggregate or other filler.

25. A method according to any one of claims 20 to 24, wherein the bituminous binder layer has glass or other fibres distributed therein.

26. A method according to claim 15 or 19 or any preceding claim appendant thereto, wherein the surface overlay is a black top overlay of at least 30 mm thickness.

27. A method according to claim 15 or 19 or any preceding claim appendant thereto, wherein the surface overlay comprises a bituminous layer strengthened with glass or other fibres and provided with a surface layer of chippings or the like.

28. A material according to any one of claims 1 to 11 or a method of any one of claims 12 to 27, wherein the rubber chips and metal fibres or wire have been obtained by chopping up metal reinforced vehicle tyres.

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29. A method of repairing or surfacing roads, parking areas, aircraft pavements and other load bearing areas, such method being substantially as hereinbefore described.

30. A load bearing area which has been repaired or surfaced using the method of any one of claims 12 to 28.

31. A material for use in repairing or servicing roads, parking areas, aircraft pavements and other load bearing areas, such material being substantially as hereinbefore described.

Published 1990 at The Patent Office, State House, 66 71 High Holborn, London WCIR4TP.FLirtrer copies maybe obtained from The Patent Office Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1/87