EP2088241A1

EP2088241A1 - Curb element for providing boundaries in a pavement

Info

Publication number: EP2088241A1
Application number: EP09152326A
Authority: EP
Inventors: Johannus Everhardus Francis Leeuwis
Original assignee: Hanenberg Wegenbouw BV
Current assignee: Hanenberg Wegenbouw BV
Priority date: 2008-02-07
Filing date: 2009-02-06
Publication date: 2009-08-12
Anticipated expiration: 2029-02-06
Also published as: EP2088241B1; NL2001264C2

Abstract

A curb element (1, 1A, 1B, 1C) for bounding edges in pavement. The curb element is formed as an oblong, substantially rectangular spatial polyhedron, equipped with a substantially closed elongated top face (3, 3A, 3B, 3C) and at least one substantially closed elongated frontal face (15, 15A, 15B, 15C). Here, the curb element is designed in a first material with a first density, of which the top face and the frontal face form part and wherein internally of the upper surface and the frontal face a space is recessed, which extends substantially parallel to the top face and frontal face.

Description

The invention relates to a curb element for bounding edges in pavement.
The known curb elements, such as used in paving for straight and curved curbstones, for enclosing corners, for tree circle and driveways, are designed in concrete. Concrete has a density of 2,000 to 2,300 kg/m³ and, with the standard lengths of 750 cm to 100 cm for this type of curb element, weights of over 50 kg running up to approximately 120 kg are quite frequent. For all these curbs it holds that in their current concrete design, and in view of recent stricter health and safety regulations for working conditions, it is no longer allowed that they are carried or moved by two individuals. For instance, in the working conditions policy rule Arbo 5.3 "Lifting on the building site", which has come into effect in the Netherlands, it is laid down that one person is allowed to lift at most 25 kg and two persons at most 50 kg. In most cases, the weight of a concrete curb element of the presently current shape will need to be divided over as many as three to five persons. Not only is this impractical, it can also cause unsafe work situations. The use of machine force could obviate this drawback but is not applicable or available in all situations. Also, reduction of the sizes and hence the weight of the curb elements is not a good alternative because this compromises the soundness and durability of the paving. Also, smaller elements adversely affect the efficiency of the pavement.
It is, for instance, not uncommon in practice that manual placement and adjustment of a curbstone with dimensions of, for instance, 13/15 x 25/100 cm, 18/20 x 25/100 cm and RWS or PWS curbs such as 11.5/22.5 x 25 x 100 and also heavier confining elements is no longer allowed. The curbstones as mentioned earlier weigh approximately 85 to 115 kg per meter length. Furthermore, in small scale paving operations, the deployment of a machine is often not profitable.
Accordingly, it is an object of the present invention to eliminate or improve at least one of the drawbacks of the state of the art. It is also an object of the present invention to provide alternative constructions which are easier in manufacture and use and which furthermore can be manufactured in a comparatively less expensive manner. Alternatively, it is an object of the invention to provide the public with at least a useful option.
To that end, the invention provides a curb element for bounding edges in pavement, formed as an oblong, substantially rectangular spatial polyhedron, which curb element is equipped with a substantially closed elongated top face, at least one substantially closed elongated frontal face, the element being designed in a first material with a first density, of which the top face and frontal face form part, while internally of the top face and frontal face, a space is recessed which extends substantially parallel to the top face and frontal face. The solution sought by the invention provides for the making of lightweight curbs by partially replacing the concrete of which the curb is made with a lighter material, such as, for instance, expanded polystyrene (EPS). More particularly, the invention provides curb elements with one or more of the features defined in the claims.
The invention can also be advantageously used in

parking elements or buffer elements (parking chocks)
steps
bollard (erected) prefab concrete elements
bicycle stands 300x300x200 mm
gutter constructions
driveway curbs (blocks).

The invention can also be advantageously used in the form of an open surfacing such as concrete paving bricks and concrete tiles.
The invention further provides a method for forming a curb element having one or more of the abovementioned features, wherein a preformed element, by means of lost spacing elements, is positioned in a mold before concrete is cast or poured therein. Further, the EPS can be covered in advance with paper or environmentally friendly foil or yet another environmentally friendly covering such as starch or the like. This prevents strong adhesion to the concrete so that separation upon recycling is easier.
The invention will presently be described in further detail with reference to the accompanying Figures, in which

Fig. 1 shows, in perspective, a straight curbstone according to a first embodiment of the invention in partial cross section;
Fig. 2 shows a straight curbstone according to a second embodiment of the invention in a view according to Fig. 1;
Fig. 3 shows, in perspective, a partially cross-sectioned core for the curbstone of Fig. 2;
Fig. 4 shows a curbstone according to a third variant embodiment in a view according to Figs. 1 and 2; and
Fig. 5 shows a curbstone according to a fourth variant embodiment in a view according to Figs. 1, 2 and 4.

Fig. 1 shows a curbstone 1 of a conventional model, which can be of the 180/200 or 130/150-type. This indication refers to the width of, each time, the top face 3 and the bottom surface 5 in millimetres. Such curbstones are usually provided in different heights, such as 160, 200 or 250 mm. These types of curbstones have a standard length of 1,000 mm and are provided at a first end face 7 with a continuous groove 9. On an opposite, second end face 11, a continuous tongue 13 is provided designed to be coupled to a groove 9 of a contiguous curbstone. It is further customary to cover these curbs on the top face 3 and on a top part 17 of the frontal face 15 with a wear layer of a few millimetres of basalt or porphyry, provided or not provided with quartz. The conventional curbs of this type, when designed in concrete, have a weight that can vary from 50 to 120 kg.
The curbstone 1, designed according to the invention, is distinguished from the existing curbstones in that it further has a core 19, which is included in a recessed space and which is formed from a material with a considerably lower density than the concrete material of which only the outside 21 is made. As a possible suitable material for the core 19, inter alia, cellular concrete (also called aerated concrete or foamed concrete) with a density of between 25 and 75% of that of solid concrete can be considered. Another possibly suitable material is a composite of concrete and polystyrene granules with a density of 10 to 25% of that of solid concrete. However, a particularly suitable material for the core 19 is formed by expanded polystyrene (PES), which has a density of only between 0.5 and 4% of that of concrete. Although other plastic foamed products, such as polyurethane foam can be considered, especially polystyrene is a highly attractive alternative owing to its recyclability.
Now that the principle of the invention has been elucidated on the basis of example of Fig. 1, a further number of alternative variants will be explained on the basis of Figs. 2, 3 and 4.
In the variant embodiment of Fig. 2, the elements corresponding to Fig. 1 are numbered with an index "A". The curbstone 1A in Fig. 2 has a closed first end face 7A and a similar closed second end face 11A. As a result, the recessed space for the core material 19A is enclosed all around not only in transverse direction but also completely enclosed in longitudinal direction. Here, the groove 9A and the tongue 13A extend completely in the material of the concrete covering 21A and thus offer even more resistance against damage during placement. This can offer advantages in particular when the grooves 9A and the tongues 13A of successive curbs 1A are placed against each other. The weight that is saved by making the core 19A from expanded polystyrene (EPS) is still considerable because the saved core material hardly reduces the bending strength of the curb. This is because the resistance momentum important to the bending strength gives the material farthest removed from the center line an exponential influence on the bending strength. Apart from bending strength, curb elements in a pavement, such as curbstones, need also have a certain resistance against impact loads. In practice, this requirement can already be met with considerably smaller concrete thickness than the thickness of an entirely concrete curb.
In Fig. 3 is shown an alternative embodiment of a core 19B from expanded polystyrene (EPS) which can be used for embodiments such as those in Figs. 1 and 2. The core 19B has an elongated form with a top face 31, a front longitudinal wall 33 and first and second ends 35, 37. The front longitudinal wall 33 may have been subdivided into a top and bottom part 39, 41 according to the contours of the frontal face 15, 15A of the concrete covering (Fig. 1 and 2), but this is not required. In particular, the core 19B is provided with recesses 43 in the front wall 33 and recesses 45 in a rear longitudinal wall 47. These recesses 43, 45 provide the front and rear walls 33, 47 with a profile. On the one side, this effects a better mechanic anchoring between the core 19B and the covering to be provided. On the other hand, reinforcing ribs are thus formed on the inside of the concrete covering which, in turn, can contribute to an enhanced impact load resistance. Naturally, the provision of recesses is not restricted to the foremost and rearmost longitudinal walls 33, 47 of the core 19B but if need be, they can also be provided on any other wall.
In the embodiments described so far, each time, the starting point was a more or less equal circumferential thickness of the concrete covering. With curbstones, it is desired that the top face 3, 3A and the frontal face 15, 15A always have the greatest resistance against impact loads. To improve this strength even further, the wall thickness of the concrete covering for these surfaces can be chosen to be greater than that on the rear and bottom side of the curb. The core 19, 19A can then be positioned off-center.
Another variant of the invention which also favourably influences the material thickness on the impact load side can be seen in Fig. 4. Here, the curb element 1B is provided with an internal hollow space 51, separated from the outside 21B by a tube element 53 from polyvinyl chloride (PVC). Here, the hollow space 51 effects, in particular, the saving of weight, while the limited amount of PVC material with a relatively low density also adds less weight than the concrete covering 21B. Furthermore, a round PVC tube 53 results in additional concrete in the transition from the top face 3B to the frontal face 15B. This, in turn, is favourable for the impact load the curbstones can be subject to. Also with the curb element 1B according to Fig. 4, use can favourably be made of a groove 9B and tongue 13B for the connection of aligned curb elements. If desired, after placement of the curb elements 1B, the hollow space 51 can be utilized as drainage canal or as cable duct for electric supply facilities. It is also conceivable that, by contrast, the hollow space 51 is still filled up with concrete after placement.
Yet another embodiment can be seen in Fig. 5, showing a curb element 1C with the top face 3C and the frontal face 15C designed in concrete as thick-walled as possible. A part of the curb element 1C is formed by a second filler material 19C which forms part of the undersurface 5C and a rear surface 6C.
Upon manufacture, curbstones with an external shape as shown in Figs. 1, 2, 4 and 5 are often poured upside down in molds so that the molds are self-releasing. In order to hold the lighter material in place, which has the tendency to float upwards, during the pouring of concrete, lost spacing elements can be used. Such spacing element can be of the type already in use for keeping rebars at a distance from the outside. Suitable spacing elements to this end are supplied by, inter alia, Stoker Beton BV at 't Harde, the Netherlands. When these spacing elements are provided with an identifying mark, or are designed in a different color, the lightweight curbs according to the invention can be made distinguishable from the conventional, non-lightweight curb elements. Upon manufacture, advantageous use can be made of prefab filling elements from expanded polystyrene (EPS). These can be expanded in advance in molds as well as be cut from commercially available plate material. In general, the EPS is placed in the mold as prefab element and may be provided with spacing elements (in the form of concrete cubes). EPS is available in many compression strengths and is nowadays of high grade quality. Pouring may take place in a traditional manner with dry concrete mortar and vibration or by means of casting molds and self-compacting concrete (high-flow concrete). This latter can be done in plastic molds that are less expensive than steel molds.
The used polystyrene material also offers advantages in recycling. It is for instance possible to protect the EPS material from adhering too strongly to the concrete by means of a nature-friendly paper or foil covering or an anti-adhesive layer such as starch. Separating the polystyrene as completely as possible upon recycling is thus simplified even further. The method already in use for recycling completely concrete curbs in a breaker can also be applied to the lightweight curbs according to the invention. After breaking, the broken material can be fed through a water bath after which the polystyrene material floats to the surface. Separate discharge can thereupon take place using a sieve or the like. As a rule, the broken concrete is reused as foundation material in road construction or as aggregate in new concrete products. The polystyrene material can also be reused in insulation, or as filler material in new products.
Although the described exemplary embodiments each time have a straight curbstone for object, the invention can be equally advantageously utilized with bend curbstones which, as bend segments of for instance 15 degrees, can have a curvature with radii of less than one meter to 15 meters or more. These elements too have an important weight advantage when use is made of the present invention. Apart from bends and straight ends, also, bend curbs, full bends, tree circle curbs and special driveway curbs can advantageously be used. This also holds for almost all other curb elements for bounding edges in pavements such as confining curbs or RWS curbs for roadway separation. The invention is not limited either to the model of curbstone shown here, and also models according to the German standard DIN 483 or the European standard EN 1340 can make use of the invention.
The invention can also advantageously be used with:

The invention can also be advantageously used in the form of an open surfacing such as concrete paving bricks and concrete tiles.
To enhance the strength, the filling of lightweight material (starting from EPS) can be covered with, for instance, Epoxy or Polyurea or the like.
Naturally, the advantages of the invention are not restricted to the working conditions, but the lower weight also provides a cost saving in transport and in the use of raw materials.
It is assumed that the construction and the operation of the present invention clearly appear from the preceding description. The invention is not limited to any embodiment described herein, and, within the reach of the skilled person, variations are possible which are understood to fall within the scope of protection. Also, all kinematic inversions are to be understood to lie within the scope of protection of the present invention. Expressions such as "consisting of", when used in this description or the accompanying claims, should not be understood to be an exhaustive enumeration, but rather to have an inclusive meaning. Terms such as "means for ..." should be read as "component formed for..." or "element constructed for ..." and are to be understood to also include all equivalents for the described structures. The use of terms such as: "critical", "advantageous", "desired" etc. is not intended to limit the invention. Furthermore, also properties that are not specifically or expressly described or claimed in the configuration according to the present invention can be comprised without departing from the scope of protection.

Claims

A curb element for bounding edges in pavements, formed as an oblong, substantially rectangular, spatial polyhedron, which curb element is equipped with a substantially closed, elongated top face, at least one substantially closed elongated frontal face, wherein the element is designed in a first material with a first density of which the top face and the frontal face form part and wherein internally of the top face and the frontal face, a space is recessed which extends substantially parallel to the top face and frontal face.
A curb element according to claim 1, wherein the recessed space is enclosed all around in transverse direction by the first material.
A curb element according to claim 2, wherein the recessed space is also enclosed in longitudinal direction by the first material.
A curb element according to claim 1, 2 or 3, wherein the recessed space is occupied by a second material with a second density which is lower than the first density.
A curb element according to any one of the preceding claims, wherein the first density of the first material is between 2000 and 2300 kg/m³.
A curb element according to claim 5, wherein the first material is substantially formed by concrete.
A curb element according to any one of the preceding claims, wherein the second density of the second material is between 15 and 1500 kg/m³.
A curb element according to claim 7, wherein the second density is between 500 and 1500 kg/m³.
A curb element according to claim 8, wherein the second material is substantially formed by cellular concrete.
A curb element according to claim 7, wherein the second density is between 200 and 500 kg/m³.
A curb element according to claim 10, wherein the second material is substantially formed by a mixture of concrete and polystyrene granules.
A curb element according to claim 7, wherein the second density is between 15 and 90 kg/cm³.
A curb element according to claim 12, wherein the second material is substantially formed by expanded polystyrene (EPS).
A curb element according to claim 12, wherein the second material is substantially formed by polyurethane foam.
A curb element according to any one of claims 7 - 14, wherein the second material is included as preformed element in the first material.
A curb element according to claim 15, wherein the second material has one or more profiled longitudinal walls.
A curb element according to claim 16, wherein the one or more profiled longitudinal walls are provided with a plurality of recesses, which extend transversely to the longitudinal direction.
A curb element according to claim 4, wherein the second material is substantially formed by air.
A curb element according to claim 18, wherein the recessed space is separated from the first material by a preformed tubular circumferential wall from polyvinyl chloride (PVC).
A method for forming a curb element, according to any one of the preceding claims, wherein a preformed element, by means of lost spacing elements, is positioned in a mold before concrete is poured or cast therein.
A method according to claim 20, wherein the preformed element prior to pouring or casting of the concrete is covered with an adhesion reducing material.
A method according to claim 20 or 21, wherein the lost spacing elements are provided with identifying marks, or are designed in a color different from the covering, for distinguishing the ready product.