EP0628678A1

EP0628678A1 - Elements for self-levelling cavity floors

Info

Publication number: EP0628678A1
Application number: EP93201627A
Authority: EP
Inventors: Floris Van Dijk
Original assignee: Ubbink Nederland BV
Current assignee: Ubbink Nederland BV
Priority date: 1993-06-08
Filing date: 1993-06-08
Publication date: 1994-12-14

Abstract

Floor element (1) made of PE or PP for cavity floors, comprising a plate (2) and a series of supporting columns (3) formed as a whole therewith, said supporting columns (3) being self-leveling. The angular plate is provided with stiffening means (13, 14, 15, 16) and is furthermore formed on the edges with trapezoidal channels (4, 5, 6, 7). The channels (4, 5) of the two connecting sides are somewhat wider and deeper than the channels (6, 7) of the other two connecting sides, in order to provide a labyrinth sealing against mortar leakage.

Description

The invention relates to a synthetic floor element for cavity floors to be poured with a hardening material which flows out of its own accord, such as plastified and/or fine-grained concrete mortar or anhydrite or the like, comprising a plate-shaped member supporting the mortar and a number of supporting columns projecting downwards therefrom for supporting the plate-shaped member, and thereby the mortar for the cavity floor to be formed, on an existing foundation.
Such floor elements are often used for forming a double floor structure, for instance when this is desired for concealing wiring, such as wires for computers. After completion of the floor, these wires can simply be conveyed through the columns to the desired location and will thereafter be out of sight. It will be understood that forming an additional floor will not only entail an additional load for the existing floor, but also for the structure of the building concerned. It is essential, therefore, to keep the weight of the cavity floor to a minimum, but to ensure at the same time that the requirements of strength are met.
Floor elements for cavity floors can be considered first of all as stay-in-place formwork plates. Although floor elements can be designed for load-bearing, this is not preferred because it will often lead to a relatively large weight. It would be better to form the cavity floor to be poured by means of the floor elements in such a way, that it can be self-supporting. A demand made of the floor elements will then be that they can hold the poured mortar and mould it in such a way that, after hardening, the layer of mortar will be able to transfer the loads excercized on it, onto the foundation.
There are many embodiments of floor elements on the market, and many have been described in patent documents. Without aiming at giving a full listing, reference is made herein to European patent application 0,197,957, European patent application 0,075,372, European patent application 0,127,037, European patent application 0,156,247, European patent application 0,385,876, European patent application 0,030,415 and European patent application 0,339,537.
It frequently happens that the existing floor or foundation is uneven, having irregularities in the range of 0,5 - 1 cm in depth or height. In that case, it could happen that the floor element can either find no support in that spot or that it will be forced upwards. In the first case, there is a danger that a hardened floor will fracture because it is not supported in that spot. In the second case the poured floor will locally be less thick, which can also create a danger of failure of the floor. On the whole, what should be aimed at is obtaining a cavity floor, which has a strength that is as uniform and as great as possible with the use of as little mortar as possible. The known floor elements are deficient in this field or the effect is brought about in a cumbersome manner.
It is a goal of the invention to provide improvement in this field, which is achieved by means of the measures described in claim 1. The columns in the floor element according to the invention provide a self-levelling action hereto, so that the top surface of the plate-shaped member can remain substantially horizontal, notwithstanding the presence of some unevenness in the foundation.
Preferred embodiments of this floor element are the subject of claims 2-10.
Another demand which should be made of floor elements for cavity floors is that it should be possible to walk on them. This is necessary, in the first place, in order to be able to arrange the floor elements on the existing foundation and, in the second place, it may be necessary, upon applying the mortar, to assist in the spreading out thereof. On the other hand, as has been remarked earlier, the weight of the floor element should be as small as possible, but the material of which the floor element is made should be as ecologically sound as possible, easy to process and not sensitive to fracture or wrinkling.
For this purpose, according to a further aspect of the invention according to the application, a floor element is provided as described in claim 11. Said measures, whether or not in combination, allow for the use of such a material with a low E-modulus, making it possible to also use, for instance, polyethylene or polypropylene for this purpose. The thickness of the material can herein be kept small, which is advantageous from both the point of view of manufacturing costs and from the point of view of weight.
Another problem which occurs often in pouring cavity floors is that of the sealing at the transitions between the mutual floor elements. The sealing problems can occur first of all along the sides of the floor elements. In order to improve this, the invention provides a floor elements as described in claim 12 and in claim 14.
The second sealing problem occurs at the vertices, where floor elements connect. In order to improve this, the invention provides floor elements as described in claim 13 and 15. It will be clear that this inventive concept is applicable on floor elements with every (possibly regular) sort of polygonal shape, such as for instance hexagonal or octaganol floor elements. A rectangular floor element is preferred.
The invention will be further explained below by means of a preferred embodiment of the floor element according to the application. The following is shown in:

Figure 1: a top view of the floor element;
Figure 2: a side view in the direction of arrow II of the floor element of figure 1;
Figure 3: a partial cross-section of the floor element of figure 1, along III-III;
Figures 4A, 4B and 4C: some possible situations for the connection of the supporting columns of the floor element of figure 1 to a foundation;
Figure 5: an illustrative representation of a supporting column which has been cut away;
Figure 6: a cross-section of an edge area of the floor element of figure 1, but in this case along VI-VI;
Figure 7: a view on a corner of the floor element of figure 1, along arrow VII;
Figure 8: a view on another corner of the floor element of figure 1, along arrow VIII; and
Figure 9: a cross-section through a communal corner area of four coupled floor elements according to figure 1.

The nesteable floor element 1 represented in figures 1 and 2 comprises a plate 2 and a series of supporting columns 3 projecting downwards therefrom, said supporting columns being arranged in rows according to a matrix. The plate 2 of the floor element 1 is rectangular with long sides 5 and 7 and short sides 4 and 6 at right angles thereto. The long side 5 and the short side 4 are formed with a continuous channel-shaped profile, as represented in figure 3, and meet in vertex 8. The long side 7 and the short side 6 are also formed with a continuous channel profile, which is essentially of a similar shape as the channel profile of the sides 4 and 5 but which is formed to fit into this, and meet in vertex 11. The long side 7 and the short side 4 meet in vertex 9 and the long side 5 and the short side 6 meet in vertex 10.
Straight channels 15 extend between the neighbouring columns 3, said channels being formed in the plate 2 and, as shown in the drawing, being open towards the top. Diagonally opposed columns 3 are interconnected by means of channels 13, which are also formed in the plate 2 and are also open towards the top and meet at intersections 14, constituted by a bowl-shaped recession from the top surface 12 of the plate 2, of which bowl-shaped recession 14 the bottom has a position which is slightly raised in relation to the bottom of the channels 13.
The floor element 1 is formed as a whole, preferably by vaccum-forming, and made from a material with a low E-modulus, for instance 600-1600 N/mm² with a wall thickness which is in general 2 to 3 mm in the plate. Every suitable synthetic material can be used, but as a consequence of the stiffness of form of the floor element which will be described later, ecologically sound materials, such as polyethylene and polypropylene, are also possible.
The columns 3 of floor element 1 are self-levelling. This will be illustrated in more detail by means of figures 3, 4A, 4B, 4C and 5. Figure 3 shows that column 3 which is shown there, which is formed here as body of revolution, passes into the top surface 12 of the plate 2 via a transition area 17. The transition area 17, 51 is at an angle β of about 45° in relation to the plate 2. The transition to the top surface 12 is determined by a pronounced edge, which also holds true for the transition 50 of the transition area 17 to the top part 19 of the column 3. Such a buckled course reduces the chance of undesired folding lines occurring in the floor element 1 when it is walked upon, or when this is heavily loaded in any other way.
The top part 19 of the column 3 comprises an outer wall 21, which is bent over at the bottom end with a torus-part-like supporting area 26 to an essentially upright wall 22 situated inside of this. At the top end, the inner wall or second wall 22 is formed as a whole with a bridge member 20, which is connected to the second wall 22 by means of an area with, in relation to the second wall 22, a reduced thickness. On the radial inner side of the bridge member 20, it passes via corner area 24 into upright wall or third wall 23 of column core 18. Column core 18 is essentially U-shaped with a roundgoing third wall 23 and a closed bottom 27.
The thickness of the bridge member 20 increases in radial inward direction from weakening 25 to corner 24, where it has a thickness which corresponds to the thickness of the third wall 23. In the exemplary dimensions given, the column core projects about 4-8 mm outside the supporting area 26, the cross-section of the column core is about 30-60 mm and the thickness of the wall of the column 3 is less than the thickness of the wall of the plate 2, for instance 1 mm. Here the weakening 25 has a thickness of 0.2-0.6 mm. In this case the radial dimension of the chamber 53, which is formed by the second wall 22, the bridge member 20 and the third wall 23 is about 5-15 mm with a depth, considered in vertical direction of the column, of between 0 (not represented) and 20 mm at the deepest point.
As was remarked earlier, the column 3 is self-levelling.
How this is done is represented in figures 4A, 4B and 4C. In figure 4A, the situation is shown with a flat foundation 30, in figure 4B the situation is shown with an elevation as unevenness in the underground 30, and in figure 4C the situation is shown with a recession as unevenness in the foundation 30. In all cases, the floor element 1 will rest, with the column 3 concerned, on foundation 30.
As can be seen in figure 3, the column core 18 projects somewhat downwards from the column part 19. When the column 3 is placed on the flat foundation 30 of figure 4A, the presence of the hinge 25 allows for a displacement of column core 18 in upward direction in relation to column part 19, until both supporting area 26 and bottom 27 come to rest on the foundation 30. Herein, the wall 23 might become slightly concave (seen in a vertical plane).
When an elevation is present locally in the foundation 30, the column core 18 can be displaced upwards even further in relation to the column member 19, for instance when an elevation with a height of several milimeters is present. In the case shown, the column 3 then rests once again with both the supporting area 26 and the bottom 27, via the elevation, on the foundation 30. This construction avoids the column 3 being pushed upwards in this spot by the elevation, as a consequence of which the plate 2 would project in this spot from the, preferably horizontal, plane of the top surface 12 of the plate 2, which would result in the floor which is to be poured eventually, to be locally less thick.
It is of course also possible that the foundation 30 has locally obtained an insufficient amount of material, so that a local recessions occurs. It is shown in figure 4C that in such a case, too, the column 3 can rest on the foundation 30, i.e. via the projecting bottom 27. The formation of cracks during use of the hardened poured cavity floor as a consequence of the floor not being supported in some places, is hereby in many cases avoided.
By making a suitable choice of (the course of) the thickness of the wall of the bridge member and connecting areas, it can also be brought about that the column core 18 can, if necessary, move out of the column part 19 even further, wherein in this example the wall 23 can become somewhat convex.
In the situations of figures 4A and 4B, the weight of the mortar on plate 2 ensures that the column member 19 is pushed downwards. In the situation of figure 4C, this force resulting from the mass is apparently insufficient, but then the weight of the mortar in column 3 ensures that column core 18 abuts the surface of the foundation 30. The represented structure allows the column core to be put into an inclined position, whereby the adaptability and the levelling ability of the column 3 concerned, and thereby of the floor element according to the invention, is further increased.
The bridge member 20 can be designed in many different ways. The shown embodiment is preferred, wherein the bridge member too defines an angle α of about 75° (a choice within the preferred range of 60-90°) with the second wall 22. This embodiment reduces the chance that the column core 18 will pass beyond deadcentre and will not be able to return to the original position. An alternative would be that the position of the hinge 24 and the relatively stiff corner 25 are interchanged.
According to another alternative, the bridge member 20 extends essentially horizontally from the second wall 22 to the third wall 23. In that case, the risk of passing beyond deadcentre is smaller and it could be considered to replace the relatively stiff corner 24 by a weakening as well, wherein then even the bridge member as a whole can be constructed in a weakened form.
Another aspect of the floor element according to the application is represented in figures 1, 3 and 5. The trapezoidal channels 15, which extend between neighbouring columns, pass about half way through into a narrower and shallower channel portion or passage 16, via a wall 56 which is positioned essentially at right angles to the channel 15. This wall 56 forms a plane of material which increases the stiffness against bending in a plane perpendicular to the axis of the channel. Furthermore, the interruption in the walls of channel 15 formed by the portion 56 also prevents the occurring of a folding line in the top edge (connection channel wall - top surface 12) of the channel wall or in the lower edge (connection channel wall - channel bottom). This might otherwise occur when someone puts his foot on the area defined by channel 15 and two neighbouring diagonal channels 13.
In figure 5 it can be clearly seen that the channels 15 with their bottom 29 connect higher to the transition area 17 of the column 3 than the diagonal channels 13 with their bottom 28. Hereby, the occurring of an essentially horizontal, tangential wrinkle or folding line at the connection is prevented. The channels 13 and 15 can have a depth of 15 to 25 mm with the aforementioned plate thickness of 2 to 3 mm. Here the step in height between the channel portion 15 and channel portion 16 can be 5 mm, and the lateral step at this position can on both sides be, for instance, 4 mm.
As a consequence of these measures, notwithstanding the fact that a material with a low E-modulus (tough material) of about 600-1600 N/mm² (PE or PP) is used, the floor element can be walked upon very well, without it being likely that the plate will buckle locally. A further advantage of the use of such a material is that sound-damping is enhanced. In spite of the large size of the floor element, the weight can furthermore be kept low and the ease of handling is good. Fracturing, especially during transport, is almost eliminated.
The bearing capacity is further increased in comparison with known floor elements for cavity floors by the asymetrical design of the floor element, as is represented in figure 1. There, it can be clearly seen that the short side 4 and the long side 5 run right next to, but just outside the columns 3, while the long side 7 and the short side 6 are situated at considerably more distance therefrom. The area between the columns 3 and the edges of the sides 6 and 7 is stiffened by channels 15' and 13'. The area between the columns 3 and the sides 4 and 5 is stiffened by channels 15''. The cross-section of the channels 15', 15'' and 13' corresponds to those of the channels 15 and 13. When floor elements of the type of figure 1 are now coupled to form a complete formwork floor for a cavity floor to be poured, then one side 5 of a first floor element will each time be coupled to a long side 7 of another, identical floor element, all this in such a way that the centre-to-centre distance of the columns situated on both sides of the coupled side is at least about equal to that of the columns in the floor elements themselves. Because the edge areas of the aforementioned sides 4 and 5, which are situated closest to the columns, are designed to receive the edge areas of the sides 6 and 7, a rather stiff bearing, with a minimal bending moment, of the sides 6 and 7 of neighbouring floor elements is brought about.
The cross-section of the channel-shaped profile of the edge areas 4 and 5 is depicted in figure 3. It can be clearly seen that the top surface 12 of the plate 2 passes into a strip 49 via a step or wall 48, said strip 49 itself ending in a trapezoidal channel 43, with wall 47, bottom 46 and opposite wall 45, which latter wall merges on the top side into an essentially horizontal supporting strip 44. Figure 6 shows a cross-sectional view of the channel-shaped edge areas of the sides 6 and 7. Here, the top surface 12 of the plate 2 passes directly into the channel 31, which is trapezoidal in shape with side walls 33 and 35 and bottom 34, wherein the side wall 33 passes at its top end into a horizontal supporting strip 32. The dimensions of the channels 31 and 43 are chosen in relation to each other in such a way, that they fit well into one another, while forming a sealing area against mortar leakage which is, considered cross-wise, long and changed in direction. As an example, the channel 31 can have a width on the top side of 20 mm with a height of 15 mm and the channel 43 can have a width at the top side of 25 m with a height of 17 mm, wherein the walls of both channels are under an angle of 15° with the vertical and the thickness of the material is 3 mm. Because of the chosen form of structure, sufficient sealing is also quaranteed if some clearance is left between both edge areas which have been fitted into one another.
When mortar is spread out over a series of coupled floor elements and is then hardened, it could still be possible that mortar could seep downwards at the vertices where, after all, four floor elements meet. In order to prevent this, the floor element according to the invention has corner areas which all differ from one another. The corner area 8 where two channels 43 meet, lets these channels merge. In the corner area 9 where the channel 43 of the short side 4 and the channel 31 of the long side 7 meet, this latter channel has been extended to near the edge of the side 4. Special solutions have also been implemented in both other corner areas. Where the channel 43 of the long side 5 and the channel 31 of the short side 6 meet, in vertex 10, the top surface 12 of the plate 2 has been extended, but a truncated-pyramid-like recess 36 has been formed therein which can have a heigth of 15 mm. There the surface 37 of the corner area 10 merges into the channel 43 of the long side 5 by means of vertical step wall 38.
In the last vertex 11, where both channels 31 meet, the top surface 12 has been raised to corner area 39 via vertical step walls 41 and 42, said corner area 39 being provided at its bottom side with a centring projection 40.
When four floor elements 1 are now coupled in one vertex, it is ensured that the vertex 8 is situated lowest. This is represented in figure 9. The following floor element is placed with vertex 9 in vertex 8 of the first floor element, the subsequent floor element is then placed with vertex 10 in vertex 9 of the preceding floor element and finally, the last floor element is placed with vertex 11 in vertex 10 of the preceding floor element. As can be seen in figure 9, with the discussed structure it is achieved that locally a level increase of only one time the thickness of top surface 12 is present. It has been found that such a corner structure prevents that, when anhydrite were used as mortar, this would drain away. The local thickening of, for instance, 3 mm does not cause any problems, especially when the floor element is provided with the columns discussed above and is therefore self-levelling.

Claims

Synthetic floor element for cavity floors to be poured with mortar or the like, comprising a plate-shaped member supporting the mortar and a number of supporting columns projecting therefrom, from the side turned away from the mortar, for supporting the plate-shaped member and thereby the mortar for the cavity floor to be formed, on an existing foundation, wherein the supporting columns are hollow and are connected at a first end to the plate-shaped member for receiving the mortar and are closed at their opposite second end, wherein the supporting columns comprise at least two portions, extending over the entire circumference of the supporting columns, said portions being connected by means of a flexible connecting portion, extending over the entire circumference, said flexible connecting portion allowing for mutual displacement in the main- or force-transferring direction of the supporting columns between the two column portions under occurring forces caused by the mortar, and wherein the two column portions and the connecting portion are formed as a whole.
Floor element according to claim 1, wherein the connecting portion comprises at least one weakening, extending in circumferential direction, functioning as a hinge.
Floor element according to claim 2, wherein one column portion comprises the second column end at least partially and forms a downwardly projecting column core which is situated radially inside the other column portion connected to the plate-shaped member.
Floor element according to claim 3, wherein said other column portion is provided with a supporting surface which extends in circumferential direction, and is situated radially outside the column core.
Floor element according to claim 4 wherein, at the radial out- and inside of its supporting surface, said other column portion has a first and a second roundgoing wall, respectively, wherein the first and the second walls together with the supporting surface define a gutter shape, roundgoing in circumferential direction, and the second wall connects to the connecting portion.
Floor element according to claim 5, wherein the column core is essentially U-shaped in cross section with a bottom and a roundgoing third wall rising from this, wherein the connecting portion connects, on the one hand, to the third wall and on the other hand to the second wall of the other column portion, wherein the second wall, the third wall and the connecting portion define a roundgoing chamber which opens downwardly.
Floor element according to claim 6, wherein the weakening is situated between the connecting portion and the second wall and/or the first wall.
Floor element according to claim 7, wherein the weakening is adjacent to the first wall or to the second wall and the connecting portion gradually increases in thickness in radial direction from the weakening, in order to form a relatively rigid corner near the transition to the second or the first wall, respectively.
Floor element according to claim 8, wherein the second wall reaches higher than the third wall, so that the connecting portion extends slantingly inwards and downwards from the second wall under an angle with the second wall, which is preferably larger than 60°, and more preferably 75°.
Floor element according to claim 7, wherein the connecting portion comprises a weakening both near the connection to the second wall and near the connection to the third wall and the connecting portion is positioned essentially transverse to the main direction of the supporting columns.
Floor element according to any one of the preceding claims, wherein the floor element is manufactured as a whole from a material with a low E-modulus, preferably with an E-modulus of 600-1600 N/mm², especially PE or PP, and has an increased bearing capacity and can be walked upon as a consequence of one or more of the following stiffening measures;
a) channels which are preferably sharp-edged, extend between the supporting columns, the channels having been formed in the plate-shaped member and being open to be side of the mortar and being essentially U-shaped,

b) in their direction of extension, the channels have two or more portions with different cross-sections, the portions being connected to each other by means of connecting faces formed as a whole with the portions and being positioned essentially transverse to the direction of extension,

c) the first end of the supporting columns merges into the plate-shaped member by means of a transition area which is shaped like a sharp bend or stepped at an angle,

d) the supporting columns are arranged in a matrix arrangement, wherein straight and diagonal channels which are open towards the top, are formed each time in the plate-shaped member between the nearby and diagonally opposed supporting columns, respectively,

e) the bottoms of the straight channels and the bottoms of the diagonal channels intersect the transition area of the column supports at different levels, respectively,

g) the diagonal channels meet in a bowl-shaped recession in the plate-shaped member, which preferably has a bottom which lies higher than the bottom of the diagonal channels,

h) the edges of the plate-shaped member are shaped as channel profiles,

i) the plate-shaped member is polygonal, preferably rectangular, and assymetrical, wherein at least one channel-shaped continuous first edge is situated relatively near but outside of the supporting columns and at least one other channel-shaped continuous second edge is situated relatively at a distance of the supporting columns, but at most in the order of a shortest column distance, wherein the channel-shaped first edge is formed to fit almost completely into the second channel-shaped edge.
Synthetic floor element for cavity floors to be poured with mortar or the like which flows out of its own accord, comprising a plate-shaped member supporting the mortar and a number of supporting columns projecting therefrom, from the side turned away from the mortar, for supporting the plate-shaped member and thereby the mortar for the cavity floor to be formed, on an existing foundation, wherein the floor element is polygonal and has a first channel-shaped edge area along at least one side, preferably with trapezoidal-shaped cross-section, and has a second channel-shaped edge area along at least a first side, said second channel-shaped edge area being formed in a similar manner, but in such a way that the second edge area of a plate-shaped member fits in the first edge area of another, identical plate-shaped member, thereby forming a sealing of a labyrinthic shape against mortar.
Floor element according to claim 12, of which at least three corner areas differ from each other in shape and/or dimensions, so as to define first, second and third, etc. corner areas, which are situated outside the columns and can be fitted together with respective corner areas with different labels (for instance in the case of three corner areas, second and third, first and third and first and second corner areas, respectively), of adjoining, identical floor elements, thereby forming a sealing agaist leakage of mortar.
Synthetic floor element for cavity floors to be poured with mortar or the like which flows out of its own accord, comprising a plate-shaped member supporting the mortar and a number of supporting columns projecting therefrom, from the side turned away from the mortar, for supporting the plate-shaped member and thereby the mortar for the cavity floor to be formed, on an existing foundation, wherein the floor element is rectangular and is formed in a channel-shape, preferably with a trapezoidal cross-section, along two first edge areas connecting to each other, and is shaped in a similar way along the second edge areas connecting to each other, but in such a way that the second edge areas of a plate-shaped member fit into the first edge areas of another, identical plate-shaped member, thereby forming a sealing of a labyrinthic shape against mortar.
Floor element according to claim 13, wherein both first channel-shaped edge areas merge into one another near a first corner of the plate-shaped member and have upper edges which are situated below the upper edge of the second channel-shaped edge areas, over a distance somewhat in the order of size of the thickness of the wall, both second channel-shaped edge areas end in a first corner plate situated somewhat above the channel edges thereof near a second corner situated diagonally opposite the first corner, wherein in a third corner of the plate-shaped member a second channel-shaped edge area is extended and, in a fourth corner situated diagonally opposite from this, a first channel-shaped edge area and a second channel-shaped edge area end in a second corner plate of which the top surface lies in one plane with the upper edges of the second channel-shaped edge areas and is provided with a recession fitting in the channel-shaped second edge area and wherein the first corner plate is preferably provided with a downwards projection which fits into the recession of the second corner plate.