GB2251624A

GB2251624A - Bituminous surfacing material

Info

Publication number: GB2251624A
Application number: GB9100700A
Authority: GB
Inventors: James Mcintosh; Graham John Lucas
Original assignee: Fibrescreed Ltd
Current assignee: Fibrescreed Ltd
Priority date: 1991-01-14
Filing date: 1991-01-14
Publication date: 1992-07-15
Also published as: GB9100700D0

Abstract

A bituminous material for finishing the filling of trenches in paths or for acting as a surfacing material or as a water- proofing membrane for paths, roads, and pavements comprises rubberised bitumen filled with up to 80% by weight of woodchips, preferably also containing sand and strengthening glass fibres.

Description

"BITUMINOUS SURFACING MATERIAL" This invention relates to an improved bituminous surfacing material which, in a preferred aspect, is particularly suitable for use in completing the filling of narrow trenches in footways and the like, but in other aspects is useful as a general surfacing layer or as a waterproofing membrane for interposition between a supporting surface and an overlying layer or layers of other surfacing materials.

One particular problem which arises at the present time is in the filling of relatively narrow trenches in footways where conventionally a Macadam layer has been rolled into the trench with the problem that either there is insufficient material in the trench such that it is not properly compacted because the roller is supported by the surface on either side of the edges of the trench, or it stands proud of the surrounding surfaces because of an excess of material being applied and thus leads to the surface being uneven. Furthermore, with such conventional repairs, the line of the trench is so obvious to the eye as to be aesthetically displeasing.

The material of the present invention can readily be applied level with the edges of the top of the trench as a finishing layer, is waterproof and can readily have a dressing applied thereto, to match the existing footway so that after very little weathering the line of the trench will be substantially indistinguishable. This method is particularly suitable for relatively narrow trenches as are being used, approximately 300 mm wide, when installing cable television. The material of the present invention also has the advantage of having a substantially smaller specific gravity than materials at present used, thus enabling the material to cover a greater area per unit weight laid, with a consequent cost saving.

In other aspects of the present invention, the material is usable as a waterproofing layer which may be either applied as a top layer or as an intermediate layer or membrane in the surface of a road, pathway, aircraft pavement or virtually any other walk-on or drive-on surface. The material may also be used for the sealing of cracks and joints in roads, runways, aircraft pavements or the like.

According to one aspect of the present invention, there is provided a bituminous surfacing material comprising a mixture of woodchips and rubberised bitumen.

Preferably, the material also comprises sand and glass fibres with a particular composition comprising 30 to 80%, preferably 50 to 75%, woodchips, up to 5% sand and up to 1% glass fibres, by weight.

The size of the woodchips can vary, depending upon the layer of material to be applied and while one might consider the maximum dimension as being about 40 mm, where one is applying a quite thick layer of the material, in general it is preferred that the chips will be substantially smaller, with a maximum dimension of 10 mm or less, with a particularly suitable woodchip having a maximum dimension of about 6 mm. Generally, when processing wood to obtain the woodchips, a mixture will be obtained having a substantial range of dimensions, from the size of fine sawdust upwards to the maximum dimension quoted above.

The material can also contain aggregate and/or rubber chips, preferably with a maximum dimension similar to that of the woodchips and by using such variations, the material can be made harder or more resilient as required for a particular site of use.

A further aspect of the invention provides a surfacing layer for a road, pavement or other surface comprising a layer of the surfacing material in accordance with the invention. Another aspect of the invention provides a method of repairing a trench in a road, pathway, aircraft pavement or the like, wherein after the trench has been substantially filled, the final filling is comprised by hot applying a layer of the material in accordance with the invention.

A further aspect of the invention provides a method of applying a waterproof membrane to an underlying surface which comprises hot applying material in accordance with the invention.

It has been found that with the material of the present invention utilising the wood filler instead of conventional filler not only provides a product of smaller specific gravity but also requires less mixing time with consequent saving in expense. The rubberised bitumen can be of a known type comprising synthetic rubber blended with the bitumen and may itself comprise thermoplastic rubber copolymer material with the copolymer material itself preferably being styrene butadiene styrene (SBS) or styrene isoprene styrene (SIS). Suitable rubberised bitumen materials which may be used are disclosed in our co-pending British Application No 90 23112.7.

As regards the woodchips, these in any particular example will normally comprise a mixture of chips of varying dimensions up to chips having a particular maximum dimension. A particularly suitable woodchip has been obtained by passing shredded wood through a granulator having a screen with 6 mm diameter holes. Some of the woodchips will then have a maximum dimension of around 6 mm or slightly larger with the majority of the wood having a smaller maximum dimension but being bigger than fine wood dust, also present.

The finished material has some degree of resilience and flexibility, is readily hot applied and when applied to a clean, dry surface, is adherent and waterproof. Suitably, the material can be applied to an underlayer of Macadam, conventional concrete, foam concrete or lean mix concrete.

When used to fill the top of a trench, suitably a screed box will apply the layer up to 40 mm thick but preferably at a relatively thin layer of 10 to 20 mm. The screed box spans the edges of the trench supported upon the surfaces on either side of the trench, into which the trench has been cut, and can be used to fill the top of the trench to the level of the surface on either side thereof, to provide an adherent and waterproof finishing layer.

Dressing can be applied to the layer before it has fully cooled and set and then be rolled in, to provide a non-slip surface which can be matched with the surface of the path or road etc, into which the trench has been cut.

While of particular use in filling trenches, the material can also be used to provide a surfacing layer to a road or path or the like or, in other uses, can be applied as an intervening waterproof membrane, between and under or foundation layer and an upper layer of surfacing material, for example between an undersurface of concrete or the like and an overlying surface of Macadam. A further use for the material is to repair cracks or joints in roadways, aircraft pavements and the like. Normally the crack or joint will be opened and trimmed mechanically before hot applying the material using a screed box. Suitably, immediately before application of the material, the joint or crack will have loose debris removed therefrom and be dried by a blast of preferably heated air.

Surprisingly, the applicants have found no problem in applying this wood-filled bitumen material, despite the relatively high temperature, perhaps 200or, to which the bitumen is heated, during mixing and prior to laying.

Claims

1. A bituminous surfacing material comprising a mixture of woodchips and rubberised bitumen.

2. A material according to claim 1, which also comprises sand.

3. A material according to claim 1 or 2, which also comprises glass fibres.

4. A material according to any preceding claim, which comprises 30 to 80%, preferably 50 to 75%, woodchips, up to 5% sand and up to 1% glass fibres, by weight.

5. A material according to any preceding claim, wherein the woodchips have a maximum dimension of 40 mm.

6. A material according to any one of claims 1 to 4, wherein the woodchips have a maximum dimension of 6 mm.

7. A material according to claim 5 or 6, wherein the woodchips have a range of dimensions ranging from fine sawdust size upwards.

8. A material according to any preceding claim, which also contains aggregate and/or rubber chips, preferably with a maximum dimension similar to that of the woodchips.

9. A surfacing layer for a road, pavement or other surface comprising a layer of surfacing material according to any preceding claim.

10. A surfacing layer according to claim 9, when applied to a Macadam, conventional concrete, lean mix concrete or foam concrete as underlayer.

11. A surfacing layer as claimed in claim 9 or 10, wherein a surface dressing is applied to the upper surface of the surface layer.

12. A surfacing layer as claimed in claim 9, 10 or 11, which is applied as the surface layer of a filling to a trench.

13. A surfacing layer according to claim 9 or 10, which has been applied as a porous membrane and subsequently covered with a further layer of Macadam or other surfacing material.

14. A method of repairing a trench in a road, pathway, aircraft pavement or the like, wherein after the trench has been substantially filled, the final filling is comprised by hot applying a layer of the material of any one of claims 1 to 8.

15. A method according to claim 14, wherein the material is applied by means of a screed box which is supported by the surfaces on either side of the top edges of the trench and moved along the trench to distribute material to the level of the supporting surfaces.

16. A method according to claim 14 or 15, wherein a dressing is applied and partially embedded in the top surface of the layer while the material of the layer is still soft.

17. A method of applying a waterproofing membrane to an underlying surface which comprises hot applying material as claimed in any one of claims 1 to 8.

18. A method of surfacing which comprises carrying out the method of claim 17 and then applying a surfacing layer thereto.

19. A method of repairing cracks and joints wich comprises hot applying into the crack or joint material as claimed in any one of claims 1 to 8.

20. A bituminous surfacing material substantially as hereinbefore described.

21. A surface layer substantially as hereinbefore described.

22. A method of repairing a trench substantially as hereinbefore described.

23. A method of applying a waterproofing membrane or of repairing a crack or joint substantially as hereinbefore described.