GB2053329A

GB2053329A - Road surfacing

Info

Publication number: GB2053329A
Application number: GB7917867A
Authority: GB
Original assignee: Marcham & Son Ltd J
Current assignee: Marcham & Son Ltd J
Priority date: 1979-05-23
Filing date: 1979-05-23
Publication date: 1981-02-04

Abstract

A road or like construction has a wearing course (4) comprising a compacted composition including an aggregate (5) and a binder (6) therefor, such as tar or bituminous macadam. Hardened cementitious material (8) such as Portland Cement is located in the voids (7) between adjacent particles of aggregate in the wearing surface of the course. The cementitious material may be applied to the wearing course in dry powder form by means of a brush. <IMAGE>

Description

SPECIFICATION Improvements in or relating to roads or the like This invention relates to roads and like constructions, such as pedestrian pathways, car parks, cycle tracks, and hard standings, for supporting pedestrian and/or vehicular traffic.

Conventionally, such constructions have a wearing course formed either from concrete or from compositions such as bituminous macadam or tar macadam which comprise an aggregate held together by a flexible binder. The use of concrete is very satisfactory from the point of view of wear but suffers from the disadvantage that it is necessary to allow the concrete to set for several days after it has been laid before the road or the like can be used. Thus traffic flow is disturbed for a relatively long time. Constructions based on the use of materials such as tar or bituminous macadam on the other hand can be laid very quickly in as much as it is merely necessary to apply the material and then to compact it by rolling. Moreover roads and the like produced in this way can be used by traffic more or less immediately after they have been laid.They do, however, have the disadvantage that their wearing properties are not as good as that of concrete constructions. Moreover, they are more susceptible to damage by frost during adverse weather conditions.

It is an object of the present invention to provide a road or like construction which does not suffer from these disadvantages.

According to one aspect of the present invention there is provided a road or like construction having a wearing course comprising a compacted composition including an aggregate and a binder therefor, hardened cementitious material being located between adjacent particles of aggregate in the wearing surface of the source.

According to another aspect of the present invention there is provided a method of producing the wearing course of a road or like construction which method comprises the steps of forming a layer of a composition comprising an aggregate and a binder having a surface including a plurality of voids, applying cementitious material to the surface so that it enters the voids, and allowing the cementitious material to set in the voids to form the desired wearing course.

Said composition may be tar macadam or bituminous macadam of an appropriate character.

Particularly suitable materials of this type are described in British Standard Specification No.

4987 of 1 973. In this regard, particular reference may be made to Section 2.3 of that Standard Specification which describes various macadam materials for use in producing wearing courses.

Materials described in that specification and which are particularly suitable for use in accordance with the present invention are the material described in Section 2.3.1 which is an open textured material including aggregate having a nominal size of 14 mm, the material described in Section 2.3.2 which is an open textured material including aggregate of a nominal size of 10 mm, the material described in Section 2.3.3 which is a medium textured material including aggregate of a nominal size of 6 mm and intended for light paths, footways and playgrounds, the material described in Section 2.3.6 which is a coarse cold asphaltic material including aggregate having a nominal size of 10 mm, and the material described in Section 2.3.7 which is a fine textured asphaltic material including aggregate having a nominal size of 6 mm.

Essentially, the main requirement of the composition is that it should be such that after being laid and compacted it has a free surface which includes a plurality of voids between adjacent particles of aggregate. Thus asphalts and hot rolled materials will not generally be suitable in as much as they do not ordinarily include surface voids.

The cementitious material applied to the composition after laying may be any cementitious material capable of setting to produce a hard durable substance. Thus, it may be any of the conventional cements used in the production of concrete such as Portland cement. It is important that the cement remains in the voids at the surface of the layer and does not penetrate into the underlying regions of the layer. It has been found that this can best be achieved by applying the cementitious material in a dry powder form by effectively brushing the material over the free surface of the layer so that the material is brushed into the voids. The cementitious material can then be allowed to set due to the action of atmospheric moisture and it will normally harden off within a few days to form a hard wearing surface.The road or the like can, however, be used before this since the matrix provided by the tar or bituminous macadam or the like is sufficiently strong to support traffic irrespective of whether or not the cementitious material has set.

The fact that tar or bituminous macadam materials and cementitious material can be used together in accordance with the invention is most surprising in view of the knowledge that roads and the like formed of tar and bituminous materials are relatively flexible whereas roads and the like based on cementitious materials are rigid and inflexible.

The present invention is particularly suitable for use in providing wearing courses in areas where slow moving vehicular traffic is encountered such as for example in car parks, depots, hard standing and the like and in areas which are intended to be subjected to pedestrian traffic such as footpaths and walkways.

For a better understanding of the invention and to show how the same may be carried into effect reference will now be made by way of example to the accompanying drawing which shows a crosssection of a construction prepared in accordance with the method of the present invention.

Referring to the drawing the construction includes a conventional sub-layer 1 formed, for example, from tar or bituminous macadam based on fairly large aggregate 2 coated with, and bound together by, a tar or bituminous material 3. A wearing course 4 is laid on this sub-layer 1. The wearing course is formed by applying to the sublayer a composition comprising relatively small aggregate 5 coated with, and bound together by, tar or bituminous material 6. The composition is then compacted by rolling. The nature of the composition is such that, after rolling, voids 7 are present between adjacent particles of aggregate.

In accordance with the present invention, a dry cementitious material is then applied to the free surface of the wearing course and worked in with a brush so that it enters the voids in the surface as shown by reference numeral 8. The cementitious material 8 may be based on Portland cement and is allowed to set in the voids as a result of the affects of atmospheric moisture. This ordinarily occurs within a few days but the road can be used by traffic before this has occurred.

The wearing surface of the wearing course 4 is thus composed of coated aggregate 5 and hardened cementitious material 8.

Claims

1. A road or like construction having a wearing course comprising a compacted composition including an aggregate and a binder therefor, hardened cementitious material being located between adjacent particles of aggregate in the wearing surface of the course.

2. A construction as claimed in Claim 1 wherein said composition is a tar macadam or a bituminous macadam.

3. A construction as claimed in Claim 1 or 2 wherein the aggregate in the composition has a particle size of from 6 mm to 14 mm.

4. A construction as claimed in any one of the preceding claims wherein the cementitious material is Portland cement.

5. A construction as claimed in Claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

6. A method of producing the wearing course of a road or like construction which method comprises the steps of forming a layer of a composition comprising an aggregate and a binder having a surface including a plurality of voids, applying cementitious material to the surface so that it enters the voids, and allowing the cementitious material to set in the voids to form the desired wearing course.

7. A method in accordance with Claim 6 wherein the composition is a tar macadam or a bituminous macadam.

8. A method in accordance with Claim 6 or 7 wherein the aggregate in the composition has a particle size of from 6 mm to 14 mm.

9. A method in accordance with Claim 6, 7 or 8 wherein the cementitious material is Portland cement.

10. A method in accordance with any one of Claims 6 to 9 wherein the cementitious material is applied to the surface in dry powder form.

1 A method in accordance with Claim 10 wherein the cementitious material is applied by means of a brush.

12. A method in accordance with Claim 10 or 11 wherein the cementitious material is allowed to set by the action of atmospheric moisture.

13. A method in accordance with Claim 6 substantially as hereinbefore described with reference to the accompanying drawing.

14. A road or like construction whenever produced by the method claimed in any one of Claims 6 to 13.