GB2437085A

GB2437085A - Method of applying a reflective surfacing to a road

Info

Publication number: GB2437085A
Application number: GB0706684A
Authority: GB
Inventors: Howard Lloyd Robinson
Original assignee: Tarmac Ltd
Current assignee: Tarmac Ltd
Priority date: 2006-04-13
Filing date: 2007-04-05
Publication date: 2007-10-17
Also published as: GB0607430D0; GB0706684D0

Abstract

The method, particularly for use at junctions, crossroads and the like, comprises providing an upper course 24 on a road in an unset state upon which an aggregate 25a which has been coated with a reflective coating 25b is laid, after which the coated aggregate is rolled into the upper course and the upper course permitted to set. The upper course may comprise the surface course of the road, e.g. comprising hot asphalt, with the aggregate being rolled in prior to the course fully hardening. Alternatively the upper course may comprise a dressing such as a resin that is placed on the top course 22 of the road. The aggregate is preferably gritstone, basalt or granite and the reflective coating is preferably a resin which includes a microscopic glass beads and which may include a pigment. Anti-skid particles such as Bauxite or steel slag may be laid with the aggregate.

Description

Title: A Method of Applying a Reflective Surfacing to an Area of Road

Descriotion of Invention The invention relates to a method of applying a reflective road surfacing to a area of road.

It has been known for many years to use materials for road marking, e.g. for lines to delineate lanes on a highway or for indication of priorities at junctions, which are either reflective or luminescent, as they make the road markings much more visible in many Conditions than would otherwise be the case.

Examples are described in the following patent documents: US 3,253,146, US 4,573,763, US 4,815,818, US 2004/0146349 Al and WO 00/24969. Such products are used in high traffic areas with the aim of reducing the risk of accidents occurring.

However, the use of these products is limited to small areas of coverage, i.e. road markings, due to nature of their properties. It is now considered desirable by the applicant to be able to coat whole roads or large areas of road sections with a reflective surfacing such as large areas at the approaches to junctions where accidents are common to ensure that drivers cannot fail to notice that they are arriving at such a junction. Such an approach is considered appropriate for example at 1-junctions and cross roads where it is common for drivers approaching from the or a road without priority, to fail to stop.

According to the present invention there is provided a method of applying a reflective surfacing to a road area, the method including providing the road area with an upper course in an unset state, coating aggregate with a reflective coating, laying the coated aggregate on the upper course, and pressing the coated aggregate into the unset upper course to incorporate the coated aggregate into the upper course of the road area, and permitting the upper course to set.

Whereas it has been proposed e.g. in US3253146 to incorporate relatively large coated reflective glass beads into an upper course of a road area, the use of such large glass particles can affect the skid resistance of the road, whereas this is avoided in the present invention by using aggregate with a reflective coating incorporated into the upper course, to provide the reflective surfacing.

In one embodiment of the invention, the upper course of the road area is a surface course, for example of asphalt, and the coated aggregate is laid on the surface course before the asphalt has fully hardened, and pressed thus to become incorporated in the surface course thus to provide the reflective surfacing. Where the upper course is a surface course of asphalt, the surface course will be hot when the coated aggregate is laid. In this case, preferably the surface course is at least 20mm deep and preferably between 20mm and 50mm deep. Once the coated aggregate is pressed into the surface course, the coated aggregate may be incorporated into the surface course.

In another example, the upper course is a dressing applied to the surface course of the road area, such as for example, a dressing of resin binder, such as an epoxy or other resin binder, and the coated aggregate is laid on the resin binder or other dressing before the resin binder or other dressing has fully hardened, and the coated aggregate is pressed thus to become incorporated in the dressing and provide the reflective surfacing.

In each case, the road area may include a course beneath the upper course which may be of asphalt or the like.

Preferably the coated aggregate has an average particle size (passing mesh size) of between 6 mm and 20 mm and is of the kind which conventionally is used as a road surface course material, for examples only gritstone, steel slag, and/or basalt and/or granite for examples. In addition to the coated particles, anti-skid aggregate particles, such as of calcined Bauxite and/or steel slag may be laid. Such anti-skid aggregate particles may have a particle size in the order of 1 mm to 3 mm.

The reflective coating which is applied to the aggregate may include resin and may include a matrix of microscopic glass beads, the beads for example having a size of less than 200 pm, and preferably ess than 40 pm and yet more preferably less than 20 pm.

The resin may be a polyurethane, epoxy, acrylic or thermoplastic resin, but in each case, the coating may include a pigment. For example, where a very bright road surface is required, the pigment may be Titanium Dioxide, but other pigments may be used as required Thus the road surface may be coloured by the reflective coating on the aggregate.

The reflective coating may be applied to the aggregate by mixing the aggregate and coating in a mixer prior to laying the coated aggregate on the upper course of the road area.

According to a second aspect of the invention we provide a road area having a reflective coating applied thereto by the method of the first aspect of the invention.

Embodiments of methods of applying a reflective road surfacing according to the invention will now be described, by way of example only, with reference to the accompanying drawings in which: FIGURE 1 illustrates a T-junctior, with conventional road markings; FIGURE 2 illustrates the T-junction of Figure 1 with an reflective upper surfacing applied by the method of the invention; FIGURE 3 is a cross-section through a part of a road area to which a reflective road surfacing is being apphed, at a first stage; FIGURE 4 is a cross-section through the part of the road area of Figure 3 at a further stage in the method; FIGURE 5 is a cross-section through the part of the road area of Figure 4 at a yet later stage.

FIGURE 6 is a view similar to Figure 5, but of an alternative road area.

Referring to Figure 1 a 1-junction 10 is illustrated with conventional road markings 11. At some such junctions 10 there is a problem with drivers approaching from a side road 12 which do not have priority, failing to stop, due for example to a rise just before the junction 10 and/or as a result noticing the junction 10 too late. Those drivers therefore pass into the path of vehicles travelling along the more major road 13 with priority, or simply pass across that road 13 and collide with barriers or other objects on the far side of the junction 10. Either way an accident occurs.

In figure 2, a use of the invention is illustrated in this context, where an area of the side road 12 before the junction 10 has a reflective surfacing 20 applied to it, thus making the junction 10 much more apparent than is otherwise the case. In the situation described above, where there is a rise before the junction 10 which prevents a clear view of the junction 10 until the driver is very close, applying the reflective surfacing 20 on the section of the side road 12 prior to such rise, may make drivers more aware of the upcoming junction before they can actually see it. There are of course many other situations in which a reflective surfacing 20 may beneficially be applied by the method of the invention.

Referring to figure 3, there is shown an area of road 13 which includes a prepared base course 22 which may be of asphalt, concrete or any other desired material. The road area 13 also includes an upper course 24 which as shown in the figure, is in an unset and unrolled condition but will become the surface course of the road area 13. In this example the upper course 24 is also of asphalt and as shown in figure 3, being unrolled, has an uneven upper surface 23.

Referring to figure 4, the upper course 24 is shown, on which coated aggregate 25 particles have been laid. The aggregate particles 25 each include a core 25a of rock such as basalt, and/or gritstone, and/or granite or any other conventional aggregate which is used for a surface course 24 of a road. In this example, the coated aggregate particles 25 have an average size of between 6 mm and 20 mm, e.g. a size between 10 mm and 14 mm.

The aggregate particles 25a are coated with a reflective coating 25b which includes a resin, such as for examples only a polyurethane resin, or an epoxy resin or an acrylic resin or a thermoplastic resin, or a mixture of resins. In each case, preferably the coating 25b includes a pigment such as Titanium Dioxide, and a matrix of reflective glass beads. The beads need to be microscopic or at least have a small size compared to the overall coated particle 25 size.

Preferably the glass beads are all less than 200 j.im in size and more preferably are all less than 40 pm in size and yet more preferably less than 20 pm in size. The glass beads must be small enough so as not to have any detrimental effect on the skid resistance of the road area 13 to which the reflective surfacing 20 is applied. The glass beads may therefore be Ballotini beads and may be distributed through the coating.

If desired, anti-skid particles e.g. of calcined Bauxite and/or steel slag, are also applied to the unset, hot, asphalt upper course 24, but preferably such anti-skid particles will have a particle size in the order of 1 mm to 3 mm.

Preferably the reflective coating 25b is applied to the aggregate particles 25a in a mixer, such as a rotary mixer, prior to being applied to the upper course 24, possibly immediately prior to being applied. However preferably, the aggregate particles 25a are coated well prior to the step of applying the coated particles 25 to the upper course 24, so that the coating will be dry before the coated aggregate particles 25 are applied to the upper course 24.

In figure 5, there is shown the road area 13 at a yet later stage, after the upper course 24 has been rolled by a heavy road rolling machine. It can be seen that the upper course 24 has been compacted and the upper surface 23 smoothed, and the coated aggregate particles 25 have been pressed into the upper course 24 and are thus incorporated into the upper course 24 and so provide component parts of the surface course providing wear resistance, at least when the asphalt upper course 24 has fully cooled and set.

Desirably the reflective coated particles 25 are fully incorporated into the upper course 24 by the rolling method step.

Thus there is provided a reflective surfacing 20.

In another embodiment, the coated particles 25 may be incorporated in an upper course 24a, which is a surface dressing applied to an underneath surface course 24 of the road area 13, as indicated in figure 6.

The surface dressing 24a may be of the known type in which a coating of bitumen emulsion is applied e.g. sprayed onto the road surface upper course 24 after which aggregate is spread thereover and lightly rolled to provide initial adhesion of the aggregate to the bitumen. Subsequently the passage of traffic over the surface further rolls the aggregate into the bitumen. Coated particles may be included in the aggregate as required, according to the reflectivity required in the surface dressing. Possible the coated particles could be applied in selected regions only of the surface dressing.

Then the upper course 24a is rolled to incorporate the coated particles 25 into the upper course 24. As the surface dressing 24a isthin, the coated particles 25 may be incorporated into the upper surface 24a up to a depth equivalent to the thickness of the upper course 24a.

It will be appreciated that instead of rolling the upper course 24, 24a to incorporate the reflective coated aggregate 25, the aggregate may otherwise be pressed into the upper course 24, 24a.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS

1. A method of applying a reflective surfacing to an area of road, the method including providing the road area with an upper course in an unset state, coating aggregate with a reflective coating, laying the coated aggregate on the upper course, and rolling the coated aggregate into the unset upper course to incorporate the coated aggregate into the upper course of the road area, and permitting the upper course to set.

2. A method according to claim I wherein the upper course of the road area is a surface course, and the coated aggregate is laid on the surface course before the surface course has fully hardened, and is rolled thus to become incorporated in the surface course thus to provide the reflective surfacing.

3. A method according to claim 2 wherein the surface course is of asphalt and is hot when the coated aggregate is laid.

4. A method according to claim 3 wherein the surface course is at least 20mm deep and preferably between 20 mm and 50 mm deep.

5. A method according to claim 4 wherein once the coated aggregate is pressed into the wear course, the coated aggregate is incorporated into the wear course.

6. A method according to claim I wherein the upper course is a dressing applied to the surface course of the road area and the coated aggregate is laid with or on the dressing before the dressing has fully hardened, and the coated aggregate is rolled thus to become incorporated in the dressing and provide the reflective surfacing.

7. A method according to claim 6 wherein the dressing is of resin.

8. A method according to any one of the preceding claims wherein the road area includes a course beneath the upper course.

9. A method according to claim 8 wherein the course beneath the upper course is of asphalt.

10. A method according to any one of the preceding claims wherein the coated aggregate has an average particle size of between 6 mm and 20 mm and is of the kind which conventionally is used as a road surface course material.

11. A method according to claim 10 wherein the aggregate is of gritstone and/or basalt and/or granite.

12. A method according to any one of the preceding claims which includes laying anti-skid particles with the coated aggregate.

13. A method according to claim 12 wherein the anti-skid particles are of calcined Bauxite or steel slag.

14. A method according to claim 12 or claim 13 wherein the anti-skid particles have a size in the order of 1 mm to 3 mm.

15. A method according to any one of the preceding claims wherein the reflective coating which is applied to the aggregate includes resin.

16. A method according to claim 15 wherein the resin is one of a polyurethane, epoxy, acrylic or thermoplastic resin.

17. A method according to any one of the preceding claims wherein the reflective coating includes a matrix of microscopic glass beads 18. A method according to claim 17 wherein the glass beads have a size of less than 200 pm, and preferably less than 40 pm and yet more preferably less than 20 pm.

19. A method according to any one of the preceding claims wherein the reflective coating includes pigment.

20. A method according to any one of the preceding claims wherein the reflective coating is applied to the aggregate by mixing the aggregate and coating in a mixer prior to laying the coated aggregate on the upper course of the road area.

21. A method of applying a reflective surfacing to an area of road substantially as hereinbefore described with reference to the accompanying drawings.

22. A road area having a reflective coating applied thereto by the method of any one of the preceding claims.

23. Any novel feature or novel combination of features described herein and/or as shown in the accompanying drawings.