GB2115465A - Concrete road surfacing - Google Patents

Abstract

A method of surfacing a concrete road with a white reflective material includes the steps of applying to the road a water emulsion containing a water dispersible epoxy resin, laying a cement and sand screed also containing water dispersible epoxy resin, applying reflective stone chippings, and pressing down the chippings.

Description

SPECIFICATION Improved concrete road surfacing This invention relates to the surfaces or concrete roads, streets, pavements, drives, carriageways, motorways and like thoroughfares, and car parks and other paved areas, all hereafter for convenience referred to as "roads".

The term road surfacings refers to that paved surface layer of the road or part thereof which forms an integral portion of the structure of the road and the term does not include superficial road markings.

It is desirable that the surface of the road should be as white in colour as possible and should reflect light. This allows the driver of a vehicle on the road at night more easily to see the road ahead of him and to assess the position and speed of traffic ahead more clearly than would be possible on a road with a conventional surface.

Such an advantage would be especially noticeable on roads not having a system of overhead lighting.

In addition, a hazard, such as a darkly clothed pedestrian crossing a road would readily be seen at night against the light background of the surface. The movement of road traffic at night would also be more discernible to pedestrians.

It has been possible in the case of tarmacadam or other flexibie "blacktop" roads to obtain such advantages by covering the surface of the road with special stone chippings of a particular white colour. The stones are then merely rolled into the blacktop surface. If it is desired to apply the stones to existing blacktop surfaces, then a preliminary coating of bituminous material, tar, or other proprietary oil based binder is first applied to the surface, the chippings then being distributed and rolled down. Any of the dark coloured binding materials covering the exposed surfaces of the chippings is soon removed by traffic wear, leaving the desired white appearance.

Now a concrete road is a rigid material, and it is not practicable to use the foregoing processes on such a surface. Instead, a special screed needs to be applied to the top of the road, as hereafter described, and the specially treated chippings embedded therein.

According to the present invention there is provided a method of surfacing a concrete road with a white reflective material, the method consisting of the application to the road of an emulsion of water containing a water dispersible epoxy resin, laying a cement and sand screed also containing a proportion of water dispersible epoxy resin, applying thereto reflective stone chippings, and pressing down the said chippings.

Preferably the upper part of the said screed also incorporates small self polished granite flakings, which latter give additional sparkle to the light reflected by the chippings.

A water dispersible epoxy resin system in combination with a conventional cement and sand screed gives the following advantages: it allows the ability to use comparatively thin screeds; it provides improved resistance to penetration by liquids; the mechanical strength is improved including abrasion resistance, tensile, flexural and compressive strengths -- non-dusting finish, and excellent adhesion to existing concrete.

A road surface in accordance with the present invention has good light reflecting, refracting and diffusing properties, which properties persist even after considerable wear of the road surface. The reflective surface may be over the whole of the road surface or part of parts thereof. It may be laid on an existing road or on a new road. In the case of the former it is necessary to ensure that the surface to be covered is as clean as can be reasonably obtained. The removal of "traffic film" may be carried out by using dilute hydrochloric acid or caustic soda. It is however, essential to ensure that any such materials are completely removed before the commencement of the application of the reflective surfacing processes. In the case of a new road, it is preferably to apply the system whilst the latter is still in an unset state.

The depth or thickness of the screed may be varied. For instance, on a new driveway carrying very light traffic, it may be of the order of 1 5 mm to 20 mm, whereas on a busy thoroughfare it may be in excess of 40 mm.

Preferably the stone chippings are between 5 mm and 30 mm gauge. Preferably the chippings are pre-wetted in the water dispersible epoxy resin emulsion before being applied to the surface.

More preferably they are soaked in the emulsion for at least two hours. This process imparts additional strength to the finished surface.

Preferably the chippings are pressed into the surface by rolling.

Preferably the stone chippings are of Quartzite.

More preferably they are Anglesey Quartzite, which is a naturally occurring white grit stone, quarried near Holyhead, Isle of Anglesey.

Anglesey Ouartzite is particularly well suited for use with the present invention because of its whiteness, hardness, reflective quality, angular shape, and consequent abrasion and skid resistance.

An embodiment of the present invention will now be described by way of example only.

In this embodiment of the present invention the laying of a reflective surface on a concrete road is described.

The cleaned existing road surface or new unset road surface is sprayed with an emulsion consisting of one part of a water dispersible epoxy resin to five parts of clean water. A screed of suitable thickness is then laid on the road consisting of equal parts of Portland cement and washed sharp river sand, sufficient clean water to make a workable mix, said water containing a proportion of a water dispersible epoxy resin on the basis of 5% by weight of the dry materials cement and sand. These constituents are thoroughly mixed together and laid in an even layer. In alternative embodiments there may also be included a concrete hardener such as calcium chloride.

Before the screed has set there is distributed evenly over the surface sufficient quantities to cover approximately 95% of the area of Anglesey Quartzite chippings between 5 mm and 30 mm gauge. Said chippings are pre-soaked in the water dispersible epoxy resin emulsion. The chippings are then rolled down to leave a surface texture depth averaging approximately 1 12 mm to 22 mm.

In alternative embodiments, the chippings may include a proportion of self polished granite flakings, 3 mm to 6 mm gauge, which would give additional sparkle to the light reflected by the chippings.

Before laying the reflective surface on an existing road it is necessary to test the road for strength. Should any defects be revealed by this testing, then it would be necessary to remove and re-make or re-surface such defective part(s).

It would be relatively easy to vary the depth of the special screed to level out any unevenness in an existing road, but this is undesirable because of the cost of the epoxy resin. Accordingly, any such road should be levelled before the application of the reflective surface, using a conventional concrete or screed.

In alternative embodiments, white Portland cement could be substituted for ordinary Portland cement, thereby enhancing the white appearance of the road.

The inclusion in the screed of an air entraining agent may be found to be advantageous, and the quantity to be used might be of the order of approximately 5% of the water content.

Apart from the obvious advantage of good visibility, there lies in the invention a further advantage over and above any conventional concrete road. The latter are notoriously noisy to the occupants of moving vehicles, compared with the more widely used blacktop roads. This is because of the fact that in order to obtain a suitable texture depth to provide skid resistance, they have to be transversely ribbed continuously at approximately 5 mm intervals. This results in higher "tyre noise" and consequent discomfort for the driver and any passenger(s). The present invention obviates the necessity for this ribbing, resulting both saving the high machinery and labour costs in forming the ribbing, and allowing a more comfortable ride for the vehicle occupant(s).

Standard specifications relating to road markings (BS 3262:1976 and AMD 3786 (September, 1981)) refer solely to white and yellow lines. Such markings in either of these colours may not be sufficiently distinguishable on a road of the type proposed by the present invention. The presently used markings, i.e. lane divisions, stop and give way lines, directional arrows, STOP and SLOW signs, etc., are usually made using screed or sprayed hot applied thermoplastic road marking materials that are white in colour. Solid glass beads are sometimes incorporated and/or applied to improve reflectivity.

The most obviously contrasting colour for these markings would be black. A bituminous tack coat could first be applied to the road surface followed by the appropriate markings in a hot applied black thermoplastic material. Otherwise, in most respects they should comply with the aforesaid British Standards.

For road markings on paved areas carrying only light traffic, private driveways and car parts for example, a black chlorinated rubber paint could be used.

Road edge markings would also be in black.

The need for solid glass beads in the markings would be eliminated, allowing a considerable saving in cost.

The conventional yellow lines indicating parking restrictions would be retained, where required.

Although in the afore-described invention Anglesey Quartzite has been exemplified as the reflective chippings because of its consistent white colour and advantageous reflective qualities, it will be appreciated that any other suitable material may be used, provided it has properties of whiteness, reflective qualities, hardness and angular shape, similar to those of Anglesey Quartzite. White calcined flint chippings, for example, would be an acceptable alternative.

Claims (9)

1. A method of surfacing a concrete road with a white reflective material, the method consisting of the application to the road of an emulsion of water containing a water dispersible epoxy resin, laying a cement and said screed also containing a proportion of water dispersible epoxy resin, applying thereto reflective stone chippings, and pressing down the said chippings.

2. A method according to claim 1 wherein said screed also includes self-polished granite flakings.

3. A method according to claim 1 or claim 2 wherein the size of the stone chippings is between 5 and 30 mm gauge.

4. A method according to any of the preceding claims wherein the stone chippings are pre-wetted in the water dispersible epoxy resin emulsion before being applied to the surface.

5. A method according to any of the preceding claims wherein the chippings are pressed into the surface by rolling.

6. A method according to any of the preceding claims wherein the chippings are Quartzite.

7. A method according to claim 6 wherein the Quartzite is Anglesey Quartzite.

8. A method according to claim 1 and substantially as herein described.

9. A method of surfacing a concrete road with a white reflective material, substantially as described in the specific example.