GB2338015A

GB2338015A - Composite road plate

Info

Publication number: GB2338015A
Application number: GB9812184A
Authority: GB
Inventors: Anthony Marchant
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-06-05
Filing date: 1998-06-05
Publication date: 1999-12-08
Anticipated expiration: 2018-06-05
Also published as: GB2338015B; GB9812184D0

Abstract

A composite member for use as a road plate (1) to cover hazards such as apertures in public roads comprising a first (2) and second (3) fibre-reinforced plastic panels spaced apart by a layer of reinforcement material (5) such as foam, plywood or balsa. The underside region (3) is shown to be generally flat but may include ribs to increase strength. At least one edge region (4) defines a connecting surface between said spaced panels having an inclined surface terminating in a vertical edge part (6) and being formed of uni-directional layers of glass fibre extending in generally the same direction as the length of the edge region. A bore (9) may be provided through which a ground retaining bolt may be passed. The road plate may also incorporate rubber feet (8a) to assist in locating the plate or prevent damage to adjacent panels during storage. The top surface may be covered with a pigment to achieve a desired colour or finish.

Description

2338015 ROAD PLATE This invention is concerned with kcomposite member

which can function as a road plate, useful in covering obstructions or hazards such as apertures, bores, trenches, inspection chambers and the like in or near public or even private roads, suitable for carrying axle loads of significant weight. There is a commercial need to produce a road plate for covering or otherwise protecting such obstructions or hazards particularly to enable vehicles including heavy goods vehicles to cross or otherwise negotiate the obstruction or hazard without damage to the vehicle or road plate. It is preferable to include in such a plate some means of identifying either the owner and/or the user of such a road plate.

Presently there is commercially available a cover member (described in GB Patent 2282622B) which can be regarded as a kind of road plate in that it is for pedestrian and light vehicular traffic only. However, there is now a commercial demand for a road plate suitable for safely transporting heavy goods vehicles with axle loads in excess of 2.5 tons. Present European legislation requires that the maximum axle load allowable on a UK road is 10,500kg (i.e. 5,250kg over a single tyre footprint.) We have now devised a road plate for the purposes of enhancing safety to vehicular traffic affected by or otherwise involved in construction, repair or maintenance works on, in or adjacent to the road surface.

2 According to this invention there is provided a fibre-reinforced composite member including first and second spaced surfaces defining a space therebetween which contains reinforcement material, at least one edge region of the member defining a connecting surface between said spaced surfaces, which edge region includes an inclined surface relative to one of the said spaced surfaces and wherein such edge region has an internal construction which comprises at least one layer of unidirectional fibrous material such that the length of fibres in such fibrous material extends generally in the same direction as the length of that edge region.

In some embodiments of this invention we provide a road plate formed in the general shape of a rectangle, such as a square, providing a generally flat uppermost surface or alternatively a raised central apex to allow water drainage. Such road plates can be fabricated from glass reinforced plastic materials using a suitable core reinforcement material within the space between first and second surfaces. The structure and shape can be convenient for manufacture by resin transfer moulding or hand-laid techniques. The underside of the road plate may be solid i.e. including a generally flat lower surface or alternatively it may be ribbed for strength and to permit stacking of similarly constructed road plates.

In preferred embodiments, the present road plate can be constructed from a combination of uni- and bi-directional 3 layers of glass fibre, resin and a suitable core material (eg coremat, foam, plywood and balsa). At the edge of the plate the thickness may reduce drastically to, for example, not greater than 6 mm to ensure that the leading edge does not create a trip hazard.

In operation, using a rectangular plate, the worst loading condition for any edge region of the road plate is when it spans a hazard such as a trench and a vehicle passes across its free edge. In this case, no matter which edge is aligned with such a trench, the tendency is for it to bow with almost all of the loading along the edge or edges spanning the trench. We have surprisingly found that by using at least one layer of uni-directional (preferably glass) fibre, but preferably more, along and laid parallel to the edge as part of the internal construction of the road plate, a maximum strength can be obtained in a critical direction. In the four corners of a rectangular plate, each alternate layer of unidirectional glass fibre is preferably stopped short to minimise or- avoid overlap of such layers which permits a more or less constant thickness of the plate along each edge region including such corners.

Across the centre of the road plate, the loading can occur in any direction, and therefore the core can be faced with layers of bidirectional glass, extended across the edges for continuity. Due to problems with shear stress, the surface skin thickness is preferably more than 2 mm in the glass fibre composite construction.

- 4 The 'road plate' can be produced to a specification which will impart the properties required for both flex and stress within allowable tolerances in all modes of use when spanning a trench or bore to be capable of carrying a maximum axle load of 10,500kg.

Preferably the plate is of a glass reinforced plastic composite structure.

The overall shape and dimensions of the plate can be decided initially and a mould produced in materials to suit the chosen method of manufacture, e.g. open single face tooling, closed mould two face tooling. The tooling can be made from composite or steel as required.

The preferred resin system is Polyester. The top surface of the plate can be a pigmented gel coat to achieve the desired colour and/or finish. The reinforcement can be chopped strand and bi-directional glass mat laid above and below e.g. end grain balsa core material. The four edges of a rectangular plate can be further reinforced with additional (i.e. more than one) layers of e.g. uni-directional glass mat laid parallel to the respective edge. Preferred embodiments of the present invention can include at least two, three, four, five or six layers of uni-directional fibrous material in the internal construction of the or each edge region of the composite member. Where these additional layers of unidirectional fibrous material meet in each corner, each overlapping layer can be from an alternate direction in order to form a laminate of similar thickness in the corner to that of the respective edges, all of which are preferably of a uniform thickness.

In making the composite material to form the road plate, catalysed pigmented gel coat can be painted or sprayed into a suitable mould to the required thickness. The reinforcement and core material can be introduced into the mould and 'wet out' with the required amount of catalysed resin. When cured, the composite material road plate can be released from the mould, fettled as necessary and finished if desired with adhesive identification labels and rubber feet.

The presently contemplated road plate can be user and public - friendly and may provide a permanent identification of the obstruction/hazard and/or the organisation responsible for attending to the particular works. warning instructions can be applied to the surface of the road plate and it may have a high friction, non slip uppermost surface over which vehicles travel. The road plate can be relatively lightweight and optionally stackable and can confer the required strength for the significant axle loads of heavy goods vehicles without significant disruption or damage to the road plate in use. This is particularly the case for a preferred embodiment of the road plate which includes a minimum of 6 layers of uni-directional fibrous material within the edge region construction. The road plate can incorporate rubber feet to reduce movement in situ e.g. neoprene rubber feet although it is preferable to bolt the plate into the road surface by suitable bolts passing through 6 apertures in the road plate. A principal advantage of the road plate is that it can provide continued traffic flow over such hazards/obstruct ions previously mentioned with minimal disruption to road users.

In order that the invention may be illustrated, more easily appreciated and readily carried into effect by one skilled in the art, an embodiment of the road plate will now be described purely by way of non-limiting example only with reference to the accompanying drawings wherein:

Fig 1 is a cross sectional view through a part of a road plate, in the form of a side elevation from one corner, Fig 2 is a plan view of a typical corner detail of part of the road plate component, Figs. 3a-3c show typical loading situations upon the plate, Fig. 4 shows fabrication of a road plate using a mould and glass reinforced plastic materials, and Fig. 5 shows a preferred arrangement of unidirectional reinforcement within the internal construction of two edge parts of the composite material plate, particularly showing reinforcement at one corner.

Referring firstly to Figure 1 of the drawings we provide a road plate of composite reinforced glassfibre construction. The road plate 1 includes an upper surface panel 2 which is the main surface over which vehicular traffic may pass. The underside 3 of the road plate is shown as generally flat although other shapes are possible even 7 though not illustrated. For example the underneath surface 3 could include projecting ribs for increased strength. The upper surface panel includes an internal construction of six uni-directional glassfibre layers, laid alternately at 00 and 900. Alternatively the upper surface panel could have an internal construction based on three bi-axial glassfibre layers, of a suitable density. Such uni-directional layers may be in the region of 400-800g/m2 and such bi-axial layers 2 may be in the region of 800-1600g/m In fabrication of the road plate the resin to fibre ratio may be 0.5-1.0:1 preferably 0.65-0. 95:1 more preferably 0.800.90:1. The road plate includes an underneath surface panel 3 which may have an internal construction corresponding to that of the upper surface panel 2. More or less individual layers of glassfibre may be used depending upon the strength required and the economics involved.

The road plate 1 is of a composite material including the glassfibre-type panels 2 and 3 between which a suitable reinforcement core 5 is provided. The reinforcement may be end grain balsa although other materials are possible such as plywood, cork, expanded polystyrene and similar such materials. It is, however, preferred to use balsa wood at an 3 approximate density of 50-150kg/m The illustrated embodiment is of a generally rectangular road plate which includes four edge regions 4. Each edge region is in the nature of a sloping surface which, in use, is inclined vertically as between the underneath - 8 surface panel 3 and upper surface panel 2. Because of the nature of the preferred construction, the edge regions 4 provide a connection and are preferably integrally formed with the upper 2 and underneath 3 surface panels. There is therefore preferably a continuous surface extending between the upper surface panel 2 and the 4 edge regions 4, terminating at a vertical edge part 6 around the external periphery of the road plate.

Within each edge region 4 there is provided within the internal construction and therefore not seen separately in figure 1, a plurality of uni-directional layers of glassfibre which are positioned in parallel to the length of each edge region 4. This is indicated schematically at reference 8. It is essential to use at least one such layer of unidirectional fibrous material within an edge region but it is preferred to use more e.g. two, three, four, five, six or possibly even more such layers of uni-directional fibrous material. It is preferred for such a material to be provided in the form of glassfibre layers which have a density in the 2 region of 400-800g/m Referring next to figure 2 a corner detail of the road plate which is shown in cross section in figure 1 is depicted in figure 2. The road plate 1 has an upper surface panel 2 which is generally flat although in other embodiments which are not illustrated the surface panel can be raised or sloping e.g. to provide drainage of water. A corner part 7 is shown whereby 2 edge regions 4 are interconnected.

9 However it is preferred for the corner portion to be continuous with the edge regions and also integral with the upper surface panel 2. The road plate illustrated includes an optional bore 9 through which groundretaining anchor bolts may be affixed. The road plate may also incorporate rubber feet (item 8a in figure 1) to assist location on the ground and/or to prevent damage between adjacent panels in storage or transit. However it will be appreciated that the bores 9 and rubber feet 8a are quite optional in the construction although they form part of preferred embodiments.

Figures 3a-3c inclusive show the complete road plate which was illustrated in part in figures 1 and 2, in situ across a trench 11 in a road surface 10. The upper surface panel 2 is visible in each such figure and a representative "footprint" 12 of a wheel load is shown. Typically the wheel load represents the load applied of 5250kg by 1 wheel. The road plate is shown withstanding the applied load from and including the edge region 4 towards the centre of the panel in figure 3c. Typically the road plate 1 may be bolted to the road surface 10 by the use of ground anchor bolts (not shown) passing through suitable bores (item 9 in figures 1 and 2).

Figure 4 shows a method of constructing a road plate according to the present invention. A mould 13 including a formation 13a defining the required profile of the road plate is shown. A filled polyester gel coat is first applied to - the mould surface whereafter the required number of layers 14 of fibreglass are applied. Although in figure 4 three such layers 14 have been shown it is possible to use more or less depending upon the ultimate strength required and the economics involved. For example the three layers 14 shown could be of bi-axial glassfibre of a density approximately 2 800-1600g/m Similarly the layers 15 represent layers of glass fibre which will form the underneath surface panel of the finished road plate. Between the layers 14 and 15 there is provided a core material 5 of suitable reinforcement, such as of balsa wood, although other materials are contemplated.

The reinforcement helps to define the overall shape of the finished road plate and provides some of the load-bearing strength.

of particular significance is the use of a plurality of layers 16 within the edge region of the plate, located between or amongst the said layers 14 and 15 as part of the internal construction of each edge region. In use, similar layers 16 will be applied lengthwise (not shown) and at the opposite edge in figure 4 (again not shown) so that each of the four edge regions of the finished plate is provided at least one such layer 16 of uni-directional fibrous material within its internal construction. It is preferred that such fibrous material comprise a layer of uni-directional 2 glassfibre, typically of 400-800g/m The direction of the fibre is generally parallel to the length of each respective edge of the panel. It is Dreferred to use up to six such 11 layers 16 of uni-directional fibrous material although more may be used to provide other required strength characteristics.

Finally, figure 5 shows part of the edge construction of the road plate, whereby each corner portion 17 within the internal construction avoids overlap as between adjacent layers 16 of uni-directional fibrous material, by holding back alternate such layers. Thus it is preferred to maintain a uniform thickness at each corner portion by placing the respective unidirectional layer 16 in end abutment (18,19) and not in overlap. If these layers were overlapped at each corner portion 17 (which forms the corner part 7 in the finished road plate - see figure 2) then there would be an undesirable increase in thickness at the corner portions due to the overlap in such layers.

In fabrication of the road plate the fibrous material layers 14, 15 and 16 are impregnated with suitable resin prior to or after application in the mould by techniques which will be familiar to those skilled in the art of fabricating glassfibre composite materials.

When the resin has set the road plates can be removed from the mould 13 shown in figure 4 for subsequent use.

17,

Claims

1. A fibre-reinforced composite member including first and second spaced surfaces defining a space therebetween which contains reinforcement material, at least one edge region of the member defining a connecting surface between said spaced surfaces, which edge region includes an inclined surface relative to one of the said spaced surfaces and wherein such edge region has an internal construction which comprises at least one layer of uni-directional fibrous material such that the length of fibres in such fibrous material extends generally in the same direction as the length of that edge region.

2. A member as claimed in claim 1, in the general shape of a rectangle.

3. A member as claimed in either preceding claim, including a generally flat uppermost surface.

A member as claimed in claim 1 or 2 including a raised central apex.

5. A member as claimed in any preceding claim fabricated from glass reinforced plastic material including suitable core reinforcement material within the space between first and second surfaces.

- k 2 -

6. A member as claimed in any preceding claim in which the underside is solid in that it includes a generally flat lower surface.

7. A member as claimed in any one of claims 1 to 5, in which the underside is ribbed.

8. A member as claimed in any preceding claim constructed from a combination of uni- and bi-directional layers of glass fibre, resin and core material.

9. A member as claimed in claim 8 in which the core material is coremat, foam, plywood or balsa.

10. A member as claimed in any preceding claim wherein the thickness of the edge reduces to not greater than 6mm.

11. A member as claimed in any preceding claim wherein more than one layer of uni-directional fibrous material is included as part of the internal construction of the edge of the member, parallel to said edge, such as two to six such layers of uni-directional glass mat.

12. P. rectangular glass fibre composite member as claimed in claim 11 including four corners wherein each alternate layer of uni-directional glass fibre is stopped short to - 11+ - minimise or avoid overlap of such layers in said corners whereby the composite member has a substantially constant thickness along each edge region including said corners.

13. A composite member as claimed in any preceding claim wherein the core is faced with layers of bi-directional glass f ibre, extended across the edges.

14. A member as claimed in any preceding claim wherein the reinforcement material is chopped strand and bidirectional glass mat laid above and below end grain balsa core material.

is. A member as claimed in any preceding claim wherein each edge region includes a sloping surface, the edge region being integrally formed with the upper and underneath surface panels.

16. A member as claimed in claim 15 including a continuous surface extending between the upper surface panel and the edge regions, terminating at a vertical edge part around the external periphery of the member.

17. A member as claimed in any one of claims 11 to 16 wherein the unidirectional fibrous material are glass fibre layers having a density of 400 to 800 g/M2.

- ir -

18. A composite member as claimed in any preceding claim substantially as herein described.

19. A composite member as claimed in any one of claims 1 to 17 substantially as herein illustrated in any Figure of the accompanying drawings.