TITLE OF THE INVENTION METHOD AND PLUG USED TO REPAIR ROADS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for repairing roads and to a plug used to repair roads.

2. Description of Related Art

A typical road, or highway, structure is shown in cross-section in Figure 1. The road consists of layers 10 and 11 that act as a support structure. Layers 10 and 11 usually consist of hard core or gravel with layer 10 usually being more coarse that layer 11. On top of layers 10 and 11 is a waterproof layer 12 and on top of this is a layer 13 of tarmac.

After some time the top tarmac surface 13 will begin to deteriorate and cracks and/or holes may begin to appear in the surface usually due to wear by automotive activity. The wear may be accelerated by weather conditions, and in particular cold weather may cause the road surface to contract and expand in freezing conditions causing accelerated deterioration. Once a hole appears in the surface of the road it rapidly increases in size and becomes what is know as a pot hole. The pot hole will continue to increase in size by the continued wear of automotive activity and weather unless the pot hole is filled

in or repaired. If the pot hole is not repaired promptly the hole will continue to deteriorate and may eventually extend down to the lower layers 12, 11 and 10 of the road surface. Damage to the layers 12, 11 or 10 is costly and time consuming to repair. Ideally pot holes should be repaired as soon as possible after they have formed to protect the underlying layers of the road.

Pot holes are usually repaired by manually digging around the pot hole and repairing each of the damaged road layers. Often the quality of such a repair cannot be controlled adequately and the time taken to carry out the repair is often quite lengthy. Frequently it is necessary to close at least a part of a road or divert traffic onto another route while the repair work is carried out. The closure of part of a road, or diversion, can be very inconvenient and the cost associated with placing traffic lights to control the flow of traffic or creating a diversion can be significant. As a result, repairs to pot holes in a road surface tend to only be made when the pot holes are large enough to cause problems and/or when there are a number of pot holes on a particular stretch of road that can be repaired at the same time.

Leaving the holes until such a time is a false economy. Significant damage to the underlying layers of the road surface may be caused by the delay in repair, resulting in the necessity for subsequent, time consuming and costly rectification.

SUMMARY OF THE INVENTION

The present invention has been made with the aim of solving the above problems. In accordance with a first aspect of the invention, a plug is provided for repairing a road surface, the plug is made of an elastomeric material and comprises an anti-skid top surface.

Preferably the plug has a disk shape or a generally frusto-conical shape. Preferably the anti-skid top surface is harder than the material of the plug. It may take the form of a roughened surface of the plug.

Preferably the plug further includes at least one injection hole. Preferably the plug further includes at least one pressure blow out hole.

In accordance with a second aspect of the invention, a plug is provided for repairing a road surface, the plug comprises at least one injection hole for allowing injection of gout through the plug.

In accordance with a third aspect of the invention, a method of repairing a hole in a road is provided, the method including the steps of: making a precision cut hole in the surface of the road; and locating a plug, which includes an anti-skid top surface, into the precision cut hole.

Preferably the method further includes the step of applying resin sealant to surfaces of the precision cut hole before locating the plug.

Preferably the method further includes the step of injecting grout (e.g. quick-set bituminous concrete) though the at least one injection hole in the plug to fill a cavity between a bottom surface of the plug and a bottom of the hole. Preferably the method further includes the step of stopping injection of the grout when the grout is detected emerging from at least one pressure blow out hole in the plug.

Preferably the plug includes a hollow underside portion and an annular rim. In accordance with a fourth aspect of the invention, a method of repairing a hole in a road is provided, the method including the steps of: making a precision cut hole in the surface of the road; and locating a plug, which includes an injection hole for allowing injection of grout through the plug, into the precision cut hole. Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross-sectional view of a typical structure of a road or highway.

Figure 2 is a cross-sectional view of a pot hole repaired in accordance with a preferred embodiment.

Figures 3A and 3B show a top view and a underside view of a plug in accordance with a preferred embodiment.

Figure 4 shows a cross-sectional view of a precision cutting head in accordance with a preferred embodiment.

Figure 5 shows a cross-sectional view of the plug and injection head in accordance with a preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments described below are in relation to a typical arrangement for repairing holes in a road, although it will be appreciated that other embodiments will fall within the scope of the appended claims.

Figure 2 shows in cross-section a pot hole 15 repaired using a plug 20. Preferably the plug 20 is formed from a hard wearing material that also allows a certain amount of flexibility. This will ensure that the plug 20 remains intact after years of use but is able to deflect slightly under the pressure from car or lorry tyres. In one embodiment the plug 20 is made of an elastomeric material and may be formed from recycled lorry or car tyres. In another embodiment the plug 20 may be formed of a plastics material.

Figures 3A and 3B show perspective views of the top and underside, respectively, of the plug 20. Preferably the plug 20 includes a hollow underside portion 21 and an annular rim 25. Preferably the plug 20 also

includes a plurality of injection holes 22, and a pressure blow out hole 23. The plug 20 is shown having six injection holes 22, although it will be appreciated that the plug may include any number of injection holes 22. In another embodiment the plug 20 may include a plurality of pressure blow out holes 23. The pressure blow out hole 23 has a valve that allows passage of a material under a certain pressure, or may be an open hole. The plug 20 is shown as being disk shaped, although it will be appreciated to those skilled in the art that any shape plug 20 can be used, for example the plug 20 may be square shaped, or the plug 20 may be frusto-conical shaped. The plug 20 has parallel vertical sides 24, although in another embodiment the sides 24 may be angled or chamfered to allow easy insertion into the precision cut hole 30. The injection holes 22 and pressure blow out hole 23 are holes formed through the thickness direction of the plug 20 so as to extend from the top surface to the bottom surface of the plug 20. Returning to Figure 2, the plug 20 is located in a precision cut hole 30 which has been cut into the surface of the road. The precision cut hole 30 is preferably cut to such a precision that the plug 20 fits in the hole snugly. Preferably the precision cut hole 30 is cut to an accuracy of plus or minus 6mm. More preferably the precision cut hole 30 is cut to an accuracy of plus or minus 2.5mm. The plug 20 is sealed, to be water and weather impregnable, in the precision cut hole 30 by an adhesive sealant 35. The adhesive sealant 35 may be a resin adhesive sealant, a silicon sealant, or any other suitable sealant. The cavity between the bottom of the plug 20 and the bottom of the

pot hole 15 is filled with grout 26. Preferably the grout 26 in an unset form has a low viscosity so that it may be easily injected into the cavity and after a period of time sets to a higher viscosity. In one embodiment the grout 26 is quick-set bituminous concrete, although it may be any other suitable material. Preferably the top surface of the plug 20 includes an anti-skid surface

(not shown) that is harder than the material used to make the plug 20. In another embodiment the top surface of the plug 20 is roughened to provide an anti-skid surface. Preferably the diameter of the plug 20 is around 350mm, but any diameter may be used and for example may vary from anywhere between 100mm to 800mm. Typically the plug 20 has a thickness of about 50mm, although any suitable thickness may be used. Although preferably the plug 20 has a hollow underside portion 21 and an annular rim 25, it is not necessary to include these and in another embodiment the plug 20 may be solid. With reference to Figures 4 and 5 a method of repairing the road will be described. To repair a pot hole 15 in the surface of a road a precision cutting head 40 is used to cut the precision cut hole 30. The precision cutting head 40 is centred on the middle of pot hole and has a diameter larger than the pot hole. The precision cutting head 40 is preferably a hardened steel circular cutter including a hardened toothed lower edge 44, but any suitable means that rotates and cuts a hole may be used.

The depth of the hole 30 depends on the thickness of the plug 20 being used and/or the size of the pot hole. The depth of the precision hole is

controlled by setting the position of the depth retraining feet 42. Typically the hole 30 is formed to a depth of about 50mm, although various depths may be achieved.

Once the precision hole 30 is formed the cutter head 40 is removed and any loose material in the hole, including any moisture, is removed. Typically this is performed by using a dry pressure jet (not shown), although any other suitable means may be used.

Once the hole has been cleaned resin adhesive sealant 35 is applied to the seating surfaces of the precision cut hole 30. The plug 20 is then mounted onto the base of an injection head 50, and the plug 20 is firmly located in the hole 30. Injection head 50 includes injection tubes 52 which are inserted and held in place in the injection holes 22 of the plug 20. The injection head 50 also includes pressure restraint pads 54 to firmly hold the plug 20 in position during the repair procedure. The pressure restraint pads 54 are held securely onto the surrounding circumference of the road surface to provide stability, and firmly hold the plug 20 in the precision cut hole 30. The grout 26 is then fed under pressure through the injection tubes 52, through the plug injection holes 22 and into the cavity between the bottom of the plug 20 and the bottom of the pot hole 15. The grout 26 is injected into the cavity until the cavity is completely filled. Once the cavity is full the grout 26 will be forced through the pressure blow out hole 23 giving an indication that the pressure feeding of the grout 26 can be ceased.

By including the hollow underside portion 21 and the annular rim 25 in the plug 20, a good match between the surface of the bottom of the precision hole 30 and the lower rim of the plug can be obtained, even if the pothole diameter is small. In addition it may be possible for the annular rim 25 of the plug 20 to be forced to expand sideways by the action of the grout 26 and contact the side walls of the precision cut hole 30. This would help to form a reliably tight seal between the plug 20 and the precision cut hole 30, although it should be noted that this is not solely relied upon to provide the waterproof seal - this is accomplished by the resin adhesive sealant 35. Once this procedure is complete the injection head 50 is removed and any surplus sealant 35 and/or grout 26 material is removed from the top surface of the plug 20. The plug 20 is then protected from the movement and shock of passing vehicles while the sealant 35 and grout 26 set.

The embodiments described above provide the advantage that pot holes may be repaired in a very short time, for example in as little as two minutes, require only a minimal amount of equipment for the repair and can be carried out with minimal skill. Since the repair can be made quickly it is not necessary to close part of a road or divert traffic, and the repair can be performed at a much lower cost. Accordingly, pot holes may be repaired as soon as they appear saving considerable time and cost as compared to the conventional repair technique. In addition the arrangement guarantees consistent quality control.

Although the present invention has been described in terms of preferred embodiments, it will be appreciable that various modifications and alterations might be made by those skilled in the art without departing from the scope of the invention. The invention should therefore be measured in terms of the claims which follow.