GB2500626A

GB2500626A - Zig zag concrete floor joint apparatus

Info

Publication number: GB2500626A
Application number: GB1205359.1A
Authority: GB
Inventors: Shaun Spurrell
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-03-27
Filing date: 2012-03-27
Publication date: 2013-10-02
Also published as: GB201205359D0

Abstract

An apparatus for forming a joint between concrete floor slab panels comprises: first and second members 3, 4 which are securable to adjacent concrete floor slab panels and which are arranged to mate with one another along non-linear edges 3a, 4a, which non-linear edges 3a, 4a, in use, define the edges of the adjacent concrete floor slab panels at their upper surfaces. The surface pattern formed by the non linear edges 3a, 4a when the first and second members 3, 4 abut one another contains one or more gaps 13 in between the members 3, 4. The non-linear edges may define an angular flat topped wave form. The gaps 13 in the surface pattern are arranged in such a way that, when the first and second members 3, 4 abut one another, the members 3, 4 can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint.

Description

Aooaratus

Field of the invention

The present invention relates to an apparatus for forming a joint between concrete floor slab panels, a concrete floor comprising such an apparatus, and a method of manufacturing a concrete floor using such an apparatus.

Background to the invention

Concrete floor slabs are generally cast as adjoining slab panels and each slab panel is cast inside a formwork; this formwork defines a space in which to cast the concrete.

The formwork may be constructed from timber, steel, aluminium, plastic or the like.

The formwork may be removable, which means it is removed after the concrete has cured. Alternatively, it may be leave-in-place formwork, which forms part of the resulting concrete structure.

The formwork generally comprises one or more upright elongate divider plates, which is the concrete is cast against. The divider plates ensure that the concrete is contained within the desired space. When a number of floor slab panels are cast next to one another to form a concrete floor or slab, the divider plates generally sit in between adjacent slab panels, and dowels or dowel plates, attached to the divider plates, are used to connect the slab panels together in order to transfer loads across the joint.

During the casting of a concrete floor slab panel comprising leave-in-place formwork, the formwork should be positioned in such a way that the upper edges of the formwork coincide with the finished floor level (FFL), i.e. the level of the upper surface of the finished concrete floor slab. The slab and formwork rest on a subbase.

After casting, concrete slabs display normal drying shrinkage. This shrinkage may be exacerbated when the temperature of the concrete is reduced, for example in the case of floor slabs for freezer stores. The shrinkage of concrete floor slabs is a slow process: it can take up to two years for a concrete slab to stop shrinking.

The shrinkage of concrete slab panels generally results in the opening of the joints between the slab panels, due to each concrete slab panel shrinking away from the joint in a direction generally perpendicular to the longitudinal axis of the joint.

Known apparatuses for forming a joint between concrete floor slab panels can comprise two top plates and two supports, one support being attached to each top plate. Other known apparatuses comprise two vertical corrugated steel forms, or two edge rails. As the concrete slab panels shrink, the joint opens up with one top plate and its support, one vertical corrugated steel form or one edge rail being connected to each concrete slab panel. This results in a gap opening up in between the top plates, the vertical corrugated steel forms or the edge rails, in the direction generally perpendicular to the longitudinal axis of the joint. The top plates, vertical corrugated steel forms or edge rails have edges which, in use, define the edges of the adjacent concrete floor slab panels at their upper surfaces, and which can abut each other. In known apparatuses, these edges are complementary in shape along their length, i.e. is they touch along their length when the apparatus is in its "closed form". The complementary edges of the known top plates or vertical corrugated steel forms can form different surface patterns; examples of known surface patterns are a straight line, a sinusoidal waveform, a triangular waveform and a trapezoidal waveform.

In some situations, it may be necessary for the top plates (and their respective supports), the vertical corrugated steel forms or the edge rails to move relative to one another in a direction generally parallel to the longitudinal axis of the joint, in the absence of any movement (or with only a minimal amount of movement) in the direction generally perpendicular to the longitudinal axis of the joint. This may, for example, be the case where there is a standard concrete slab panel adjacent to a concrete slab panel which does not shrink much due to its shape and size. The latter type of slab panel is, for example, typically found around the area where dock levellers (a pre-cast concrete unit that holds an adjustable platform and is fitted at the perimeter of a warehouse where lorries are unloaded and loaded) are fitted. In these situations, a long thin strip of concrete lies alongside several larger slab panels, which can create significant longitudinal stress along the joint.

Such situations are currently commonly addressed by using top plates (or edge rails) with linear edges; i.e. the surface pattern formed is a straight line. Such top plates can allow relative movement between the top plates in a direction parallel to the longitudinal axis of the joint without the joint opening up.

In addition to this, some known top plates and vertical corrugated steel forms with complementary edges which form a non-linear surface pattern, such as those which form a pattern in the shape of a sinusoidal waveform or a triangular waveform, can allow some limited movement in a direction parallel to the longitudinal axis of the joint once the joint has opened up in the direction perpendicular to the longitudinal axis of the joint. They do not, however, allow any movement in this direction without the joint opening up in the direction perpendicular to the longitudinal axis of the joint, or with only a minimal amount of opening up in this direction.

Top plates or vertical corrugated steel forms with edges which form a non-linear is surface pattern can have significant advantages over top plates with complementary edges which form a linear surface pattern. Vehicles driving across a linear joint will experience a shock on their wheels, and the edges of slab panels will receive an equal shock. Non-linear joints can decrease or eliminate shocks given to the wheels of vehicles driving across the joint by choosing the wavelength of the non-linear edges of the resulting gap compared with the known width of vehicle wheels.

Repeated shock loads to vehicle wheels may increase vehicle maintenance costs and repeated shock loads to slab panel edges may reduce the longevity of the slab, leading to higher maintenance costs and facility downtime. However, known non-linear joints allow little or no movement in a direction parallel to the longitudinal axis of the joint without the joint opening up, or with only a minimal amount of opening up.

It is an aim of the present invention to provide an apparatus for forming a joint between concrete floor slab panels, embodiments of which can provide a joint which allows significant relative movement in the joint in a direction parallel to the longitudinal axis of the joint, in the absence of any movement, or with only a minimal amount of movement, in the direction perpendicular to the longitudinal axis of the joint, while also providing the advantages associated with a non-linear joint.

This can enhance the performance characteristics of the resulting concrete floor, significantly increase joint and floor life, and reduce or eliminate directly attributable vehicle maintenance costs and floor maintenance costs from slab panel edge impacts and facility downtime.

Statements of the invention

According to a first aspect of the invention there is provided an apparatus for forming a joint between concrete floor slab panels, the apparatus comprising: first and second members which are securable to adjacent concrete floor slab panels and which are arranged to mate with one another along non-linear edges, which non-linear edges, in use, define the edges of the adjacent concrete floor slab panels at their upper surfaces, wherein the surface pattern formed by the non-linear edges when the first and second members abut one another contains one or more gaps in is between the members, the gaps in the surface pattern being arranged in such a way that, when the first and second members abut one another, the members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint.

The term "arranged to mate with one another along non-linear edges" is to be understood as meaning that the non-linear edges of the first and second members are complementary in shape along at least part of their length.

The first and second members can abut one another, which is to be understood as meaning that when the apparatus is in its "closed" form, for example during the casting of concrete, the first and second members touch along at least part of their length. For example, the first and second members may touch at at least the maxima and/or minima in the surface pattern.

The surface pattern formed by the non-linear edges when the first and second members abut one another is the pattern which can be seen at the surface of a

S

concrete floor slab containing the joint, i.e. the pattern which can be seen when looking down at the joint from above. The surface pattern may, for example, be an oscillating / wave-like pattern, with mating peaks and troughs. The surface pattern may be in the shape of a repeating pattern.

The surface pattern formed by the non-linear edges when the first and second members abut one another contains one or more gaps in between the members, the gaps in the surface pattern being arranged in such a way that, when the first and second members abut one another, the members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint. This is to be understood as meaning that when the first and second members abut one another, i.e. the first and second members touch at at least one point, such as the maxima and/or minima in the surface pattern, the surface area of the peaks which insert into their corresponding troughs is smaller than the surface area of those troughs. There is, therefore, space on at least one side, or on each side, of each peak inside its Is corresponding trough.

When this apparatus is used as a joint between concrete floor slab panels, the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint in the absence of any movement, or with only a minimal amount of movement, in the direction perpendicular to the longitudinal axis of the joint. This means that any forces acting on the concrete slab panels in the longitudinal direction can be released at a very early stage of casting the concrete without cracking or otherwise damaging the concrete.

The term "in the direction perpendicular to the longitudinal axis of the joint" is to be understood as meaning in the direction perpendicular, or substantially perpendicular, to the longitudinal axis of the joint in the plane of the exposed surface of the concrete floor slab panels. In other words, the term "in the direction perpendicular to the longitudinal axis of the joint" is to be understood as meaning in the direction perpendicular, or substantially perpendicular, to the adjacent faces of the concrete floor slab panels.

In addition to this, any movement of the first and second members in the direction perpendicular to the longitudinal axis of the joint in this context is to be understood as meaning that at least a component of the movement of the first and second members is in the direction perpendicular to the longitudinal axis of the joint.

If the joint opens up due to the concrete slab panels moving apart in the direction perpendicular to the longitudinal axis of the joint, the first and second members can move relative to one another in the direction substantially parallel to the longitudinal axis of the joint even further, and hence the joint can accommodate relatively large movements in this direction.

Further, the joint also provides the advantages associated with a non-linear joint.

When vehicles drive over the joint, due to the chosen wavelength of the non-linear edges of the resulting gap compared with the known width of vehicle wheels, shocks given to vehicles driving across the joint can be decreased sufficiently, or eliminated, avoiding the need to fill in the surface gap.

is In an embodiment, the first and second members are formed from a metal such as, for example, steel, or from plastic.

Specific embodiment A In an embodiment, the apparatus further comprises: first and second supports, the first support being attached to or attachable to the first member, and the second support being attached to or attachable to the second member, wherein, in use, at least part of each of the first and second supports extends vertically downward along adjacent vertical faces of the concrete floor slab panels.

The adjacent vertical faces of the concrete floor slab panels are those faces of the concrete slab panels which extend from the exposed slab panel surface to the subbase and which face each other across the joint. The actual shape of these faces can be any shape which complements the shape of the joint.

The term "vertical" is to be understood as meaning substantially vertical, or a direction which is functionally interchangeable with vertical. The term "vertical" may, for example, encompass any direction within 20 degrees of the direction aligned with the direction of the force of gravity as determined with a plumb line.

In an embodiment, the first and second supports are formed from a metal such as,

for example, steel.

In an embodiment, the apparatus further comprises a divider plate for defining a boundary between adjacent concrete floor slab panels, wherein the first support is attached to and/or supported by the divider plate.

The divider plate can be any kind of plate which defines a boundary between adjacent concrete floor slab panels. This includes, for example, a metal plate (such as described in EP-A-1985759 or similar), or any other kind of boundary plate constructed from timber, steel, aluminium, plastic or any other suitable material. The divider plate can remain as part of the resulting concrete floor, or may be a Is temporary structure which is removed after the concrete floor slab on one side of the apparatus has been cast.

In an embodiment, the first support is permanently fixed to the divider plate. For example, the first support may be welded to the divider plate.

In an embodiment, the first support is formed integrally with the divider plate.

In an embodiment, the first support is attached to the divider plate with yieldable fixings. In an embodiment, the yieldable fixings comprise low tensile bolts.

Examples of such low tensile bolts are bolts formed from nylon, the threads of which can become stripped under shrinkage forces, or the shanks of which will fail under tension.

In an embodiment, the divider plate is an elongate flat section of material.

In an embodiment, the divider plate is formed from a metal such as, for example, steel. This can result in a divider plate of high mechanical strength, capable of withstanding the forces acting upon it during the casting and subsequent shrinking of concrete.

In an embodiment, the divider plate has a fold along its lower edge, such as for example a longitudinal U-fold, a longitudinal L-fold, a longitudinal V-fold or a Dutch fold (where the divider plate is completely folded back on itself). Such a fold can strengthen the divider plate.

In an embodiment, the divider plate comprises one or more apertures. In an embodiment, the apparatus further comprises one or more dowels or dowel plates for engaging through the one or more apertures. These act to connect the resulting concrete slabs together and to provide a method of load transfer between adjacent slabs. In an embodiment, the dowels or dowel plates are attached or attachable to the divider plate.

In an embodiment, the apparatus further comprises one or more sleeves which encase the one or more dowels or dowel plates on one side of the divider plate. With is the divider plate being attached to the first support, in use the sleeves would be located on the other side of the divider plate away from where it is attached to the first support. The sleeves allow movement of the concrete relative to the dowels or dowel plates. In order to allow such movement in the direction parallel to the longitudinal axis of the joint, in an embodiment the sleeves contain a gap on at least one side of the dowel, or on each side of the dowel. These gaps in the sleeves can be larger, in the longitudinal direction, than the corresponding gaps in the surface pattern formed by the non-linear edges when the first and second members abut one another, or they can be the same size or smaller. In an embodiment, the gaps in the sleeves are larger than the corresponding gaps in the surface pattern.

In an embodiment, the second support is attached to the divider plate and/or the first support with yieldable fixings. This allows for the easy installation of the apparatus, since all elements are held together. As the joint is exposed to longitudinal and/or perpendicular stresses as shrinking occurs, such yieldable fixings can fail under tension.

In an embodiment, the yieldable fixings comprise low tensile bolts. Examples of such low tensile bolts are bolts formed from nylon, the threads of which can become stripped under shrinkage forces, or the shanks of which will fail under tension. In an embodiment, the yieldable fixings (e.g. low tensile bolts) are fitted through slots in the second support, the divider plate and/or the first support, which slots extend in the direction parallel to the longitudinal axis of the joint. The slots allow for easier production assembly.

In an embodiment, the first and second supports further comprise anchor means for embedding in the concrete. The anchor means become embedded in the concrete during concrete curing and fix the supports in position relative to the concrete.

In an embodiment, the first support comprises a facing side which faces the second support, and the non-linear edge of the first member is offset from the facing side of the first support in the direction, perpendicular to the longitudinal axis of the joint, in which the first and second members can move apart, so that, when in use between two shrinking concrete slab panels, any gap which opens up between the first and second members in the direction perpendicular to the longitudinal axis of the joint is offset from any gap which opens up between the supports in the direction perpendicular to the longitudinal axis of the joint, and ideally these gaps do not overlap.

In this embodiment, when the apparatus is used as a joint between concrete floor slab panels, if, as the concrete shrinks, the first and second members move apart in the direction perpendicular to the longitudinal axis of the joint, the elongate gap which is formed between the first and second members is only as deep (vertically) as the first and second members. This gap is offset from the gap which opens up between the supports, and which extends down to the subbase between the two shrinking concrete slab panels. The gap which opens up between the first and second members is offset from the gap which opens up between the supports in the same axial plane. The two gaps do not overlap, so this joint does not contain a continuous path from the surface to the subbase. Therefore debris and vermin cannot get into the full depth shrinkage gap through the surface gap between the first and second members. Shrinkage gaps can commonly be filled in with a filler rod and a sealant resin. However, this is a labour intensive process, and it usually does not provide a final solution due to the long time it takes for concrete slabs to stop shrinking. The filler rod and sealant resin are usually applied before the concrete floor slabs have stopped shrinking, and as they continue to shrink the gap can reopen since the sealant is unable to stretch enough to accommodate the larger shrinkage gap. In addition to this, the sealant is costly and tends to age and requires removal before fresh sealant can be fined. The embodiment wherein the gap which opens up between the first and second members does not overlap with the gap which opens up between the supports does not contain a continuous path from the surface to the subbase. This apparatus, therefore, can dispense with the need to use filler rods and/or a sealant resin.

In an embodiment, at least those parts of the non-linear edge of the first member which are closest to the facing side of the first support are offset from the facing side of the first support by 5 to 200 mm in the direction, perpendicular to the longitudinal axis of the joint, in which the first and second members can move apart. In an embodiment, this range is 5 to 120 mm. In an embodiment, this range is 5 to 30 mm. For example, if the non-linear edges of the first and second members form a surface pattern in the shape of a sinusoidal waveform, then the distance between (i) the facing side of the first support and (ii) the peaks of the sinusoidal edge of the first member which lie nearest to the facing side of the first support is S to 200 mm, or 5 to 120 mm, or 5 to 30 mm, in the direction, perpendicular to the longitudinal axis of the joint, in which the first and second members can move apart.

SQecific embodiment B In an embodiment, in use, at least part of the first and second members extends vertically downward along adjacent vertical faces of the concrete floor slab panels.

As stated above, the adjacent vertical faces of the concrete floor slab panels are those faces of the concrete slab panels which extend from the exposed slab panel surface to the subbase and which face each other across the joint. The actual shape of these faces can be any shape which complements the shape of the joint.

Specific embodiment B-I In a version of specific embodiment B, in use, the first and second members extend vertically downward to the subbase. The first and second members therefore cover the adjacent vertical faces of the concrete floor slab panels all the way down to the subbase, which results in full-depth corrugated forms.

In an embodiment, the first and second members comprise one or more apertures.

In an embodiment, the apparatus further comprises one or more dowels or dowel plates for engaging through the one or more apertures. These act to connect the resulting concrete slabs together and to provide a method of load transfer between adjacent slabs. In an embodiment, each of the dowels or dowel plates is attached or attachable to the first or second member.

In an embodiment, the apparatus further comprises one or more sleeves which encase the one or more dowels or dowel plates on the concrete-facing side of the member which does not have the dowel or dowel plate attached to it. The sleeves allow movement of the concrete relative to the dowels or dowel plates. In order to allow such movement in the direction parallel to the longitudinal axis of the joint, in an embodiment the sleeves contain a gap on at least one side of the dowel, or on each side of the dowel. These gaps in the sleeves can be larger, in the longitudinal direction, than the corresponding gaps in the surface pattern formed by the non-linear edges when the first and second members abut one another, or they can be the same size or smaller. In an embodiment, the gaps in the sleeves are larger than the corresponding gaps in the surface pattern.

In an embodiment, the first and second members are attached together with yieldable fixings. This allows for the easy installation of the apparatus, since all elements are held together. As the joint is exposed to longitudinal and/or perpendicular stresses as shrinking occurs, the fixings can fail under tension.

In an embodiment, the yieldable fixings comprise low tensile bolts. Examples of such low tensile bolts are bolts formed from nylon, the threads of which can become stripped under shrinkage forces, or the shanks of which will fail under tension. In an embodiment, the yieldable fixings (e.g. low tensile bolts) are fitted through slots in the first and/or second members, which slots extend in the direction parallel to the longitudinal axis of the joint. The slots allow for easier production assembly.

In an embodiment, the first and second members further comprise anchor means for embedding in the concrete. The anchor means become embedded in the concrete during concrete curing and fix the members in position relative to the concrete.

Specific embodiment B-Il In a version of specific embodiment B, the apparatus further comprises a divider plate for defining a boundary between adjacent concrete floor slab panels, wherein the first member is attached to and/or supported by the divider plate.

The divider plate can be any kind of plate which defines a boundary between adjacent concrete floor slab panels. This includes, for example, a metal plate (such as described in EP-A-1985759 or similar), or any other kind of boundary plate constructed from timber, steel, aluminium, plastic or any other suitable material. The divider plate can remain as part of the resulting concrete floor, or may be a temporary structure which is removed after the concrete floor slab on one side of the apparatus has been cast.

In an embodiment, the first member is permanently fixed to the divider plate. For example, the first member may be welded to the divider plate.

In an embodiment, the first member is formed integrally with the divider plate.

In an embodiment, the first member is attached to the divider plate with yieldable fixings. In an embodiment, the yieldable fixings comprise low tensile bolts.

In an embodiment, the divider plate has a section which provides support for the first member.

In an embodiment, the divider plate is an elongate flat section of material.

In an embodiment, the divider plate has a fold along its lower edge, such as for example a longitudinal U-fold, a longitudinal [-fold, a longitudinal V-fold or a Dutch fold (where the divider plate is completely folded back on itself). Such a fold can strengthen the divider plate.

In an embodiment, the apparatus further comprises one or more sleeves which encase the one or more dowels or dowel plates on one side of the divider plate. With the divider plate being attached to the first member, in use the sleeves would be located on the other side of the divider plate away from where it is attached to the first member. The sleeves allow movement of the concrete relative to the dowels or dowel plates. In order to allow such movement in the direction parallel to the longitudinal axis of the joint, in an embodiment the sleeves contain a gap on at least one side of the dowel, or on each side of the dowel. These gaps in the sleeves can be larger, in the longitudinal direction, than the corresponding gaps in the surface pattern formed by the non-linear edges when the first and second members abut one another, or they can be the same size or smaller. In an embodiment, the gaps in the sleeves are larger than the corresponding gaps in the surface pattern.

In an embodiment, the second member is attached to the first member and/or the divider plate with yieldable fixings. This allows for the easy installation of the apparatus, since all elements are held together. As the joint is exposed to longitudinal and/or perpendicular stresses as shrinking occurs, such yieldable fixings can fail under tension.

In an embodiment, the yieldable fixings comprise low tensile bolts. Examples of such low tensile bolts are bolts formed from nylon, the threads of which can become stripped under shrinkage forces, or the shanks of which will fail under tension. In an embodiment, the yieldable fixings (e.g. low tensile bolts) are fitted through slots in the second member, the first member and/or the divider plate, which slots extend in the direction parallel to the longitudinal axis of the joint. The slots allow for easier production assembly.

Further preferred features The following features can apply generally to the apparatus of the invention, including, for example, specific embodiment A, specific embodiment B, specific embodiment B-I and specific embodiment B-Il.

In an embodiment, the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is at least 2 miii. In an embodiment, this distance is at least 3 mm, at least 4mm, at least 5 mm, at least mm, or at least 20 mm.

In an embodiment, the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is up to 50 mm.

In an embodiment, the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is from 3 mm up to mm.

In an embodiment, the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is from 2 mm up to mm. In an embodiment, this range can be from 2 mm up to 40 mm, from 2 mm up to 30 mm, from 2 mm up to 20 mm, from 3 mm up to 50 mm, from 3 mm up to 40mm, from 3mm upto3omm,from3 mm upto 20 mm, from4mm up to 50 mm, from 4 mm up to 40 mm, from 4 mm up to 30 mm, from 3 mm up to 20 mm, from 5 mm up to 50 mm, from 5 mm up to 40 mm, from 5 mm up to 30 mm, from 5 mm up to 20 mm, from 10 mm up to 50 mm, from 10 mm up to 40 mm, from 10 mm up to 30 mm, from 10 mm up to 20 mm, from 20 mm up to 50 mm, from 20 mm up to 40 mm, or from 20 mm up to 30 mm.

In an embodiment, the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint over a range of about 50 mm, about 40 mm, about 30 mm, about 20 mm, about 10 mm, or about S mm.

In an embodiment, the non-linear edges of the first and second members form a surface pattern in the shape of a repeating pattern. In an embodiment, the non-linear edges of each of the first and second members form a surface pattern in the shape of a waveform. The repeating surface pattern can, for example, be a sinusoidal waveform, a triangular waveform, a square waveform, a castellated waveform, a trapezoidal waveform or any combination thereof. The waveforms can comprise a series of different types of waveforms, such as e.g. a trapezoidal waveform which changes into a square waveform along the length of the surface pattern. The wavelength of the waveforms can also vary along the length of the surface pattern. Any of these waveforms may or may not have smoothed corners, such as for example a trapezoidal waveform with smoothed corners.

In an embodiment, the non-linear edges of each of the first and second members form a surface pattern in the shape of a sinusoidal waveform, a trapezoidal waveform, or a triangular waveform. In an embodiment, the non-linear edges of each of the first and second members form a surface pattern in the shape of a sinusoidal waveform. In an embodiment, the non-linear edges of each of the first and second members form a surface pattern in the shape of a trapezoidal waveform.

In an embodiment, the non-linear edges of each of the first and second members form a surface pattern in the shape of a triangular waveform.

In an embodiment, the repeating surface pattern is arranged such that at the maximum joint opening in the direction perpendicular to the longitudinal axis of the joint, the peaks of one of the non-linear edges have not withdrawn past the troughs of the other of the non-linear edges, such that at the maximum joint opening in the direction perpendicular to the longitudinal axis of the joint there is no continuous longitudinal linear gap along the central section of the gap between the two non-linear edges.

In an embodiment, the repeating surface pattern has a wavelength which is set up, for wheels and/or vehicle tyres above a certain width, such that in use when a wheel and/or vehicle tyre traverses a gap between the non-linear edges of the first and second members, as a wheel and/or vehicle tyre departs from one member, it is already in contact with the other member. In this way, wheels and/or vehicle tyres above a certain width experience no shock when traversing the gap formed between the non-linear edges of the first and second members.

The wavelength of the repeating surface pattern formed by the non-linear edges can therefore be arranged specifically to suit the dimensions of the wheels which will typically be used on the floor.

Once the dimensions of the wheels to be used on the floor are known, and an estimate has been made of the size of the gap which will result from the shrinking of the concrete in the direction perpendicular to the longitudinal axis of the joint, the wavelength of the repeating surface pattern can be set up in such a way that the lower part of a wheel of a vehicle traversing the joint is always in contact with some part of both of the non-linear edges of the first and second members. Shocks given to the vehicles driving across the joint can therefore be reduced or eliminated without the need to fill in the surface gap.

According to a second aspect of the present invention there is provided a concrete floor comprising the apparatus according to the first aspect.

According to a third aspect of the present invention there is provided a method of Is manufacturing a concrete floor, comprising the steps of (i) setting up the apparatus according to the first aspect to form at least part of an edge of a space for casting concrete; and (U) casting concrete on at least one side of the apparatus.

In an embodiment, in step (U), the concrete is cast on both sides of the apparatus, either simultaneously or sequentially.

According to a fourth aspect of the present invention there is provided a method of manufacturing a concrete floor, comprising the steps of (i) setting up the apparatus according to the embodiment of the first aspect with first and second supports and a divider plate, to form at least part of an edge of a space for casting concrete; (U) casting concrete on one side of the apparatus; (Ui) removing the divider plate; and (iv) casting concrete on the other side of the apparatus.

According to a fifth aspect of the present invention there is provided a concrete floor formed by the method of the third or fourth aspect.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and do not exclude other moieties, additives, components, integers or steps. Moreover the singular encompasses the plural unless the context otherwise requires: in particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Other features of the invention will become apparent from the following examples. Generally speaking the invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings). Thus features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. Moreover unless stated otherwise, any feature disclosed herein may be replaced by an alternative feature serving the same or a similar purpose.

Where upper and lower limits are quoted for a property, then a range of values defined by a combination of any of the upper limits with any of the lower limits may also be implied.

Specific description

Embodiments of the present invention will now be further described with reference to the accompanying figures, of which: Figure 1 shows a schematic perspective view of a first embodiment of the apparatus of the invention, with the first and second members abutting.

Figure 2 shows a schematic perspective view of the Figure 1 apparatus, with the first and second members abutting and moved relative to one another in the direction substantially parallel to the longitudinal axis of the joint.

Figure 3 shows a schematic perspective view of the Figure 1 apparatus, with the first and second members moved apart in the direction perpendicular to the longitudinal axis of the joint.

Figure 4 shows a schematic cross sectional view of the Figure 1 apparatus perpendicular to its length, with the first and second members abutting.

Figure 5 shows a schematic cross sectional view of the Figure 3 apparatus, with the first and second members moved apart in the direction perpendicular to the longitudinal axis of the joint.

Figure 6 shows a schematic plan view of the trapezoidal surface pattern formed by the non-linear edges of the first and second members and the position of the dowel plates in the Figure 1 apparatus.

Figure 7 shows a schematic perspective view of a second embodiment of the apparatus of the invention, with the first and second members abutting.

Figure 8 shows a schematic plan view of the trapezoidal surface pattern formed by the non-linear edges of the first and second members in the Figure 7 apparatus.

Figure 9 shows a schematic plan view of the trapezoidal surface pattern formed by the non-linear edges of the first and second members in the Figure 7 apparatus, with the first and second members abutting and moved relative to one another in the direction substantially parallel to the longitudinal axis of the joint.

Figure 10 shows a schematic plan view of the trapezoidal surface pattern formed by the non-linear edges of the first and second members in the Figure 7 apparatus, with the first and second members moved apart in the direction perpendicular to the longitudinal axis of the joint.

Figures 1 to 6 show a first embodiment of the apparatus of the invention. In this embodiment, divider plate 1 is attached to first support 2. First support 2 is also attached to first member 3. Second member 4 is arranged to mate with first member 3 along non-linear edges 3a, 4a, and second member 4 is attached to second support 5. In this embodiment, the first and second members 3, 4 are present in the form of top plates.

Non-linear edges 3a, 4a each form a trapezoidal surface pattern. The surface pattern formed by non-linear edges 3a, 4a when the first and second members 3, 4 abut one another contains gaps 13 in between the members 3, 4. The gaps 13 in the surface pattern are arranged in such a way that, when the first and second members 3, 4 abut one another, the members 3, 4 can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint. This is clearly shown in Figures 1 and 2: Figure 1 shows the members 3, 4 in a position where the gaps 13 on the sides of each peak are of equal size, and Figure 2 shows the situation where the first and second members 3,4 have moved relative to one another in a direction substantially parallel to the longitudinal axis of the joint, which results in the gaps 13 being present on only one side of each peak in the surface pattern.

First support 2 comprises a facing side 2a which faces the second support 5. Non-linear edge 3a of first member 3 is offset from facing side 2a of first support 2, in the direction, perpendicular to the longitudinal axis of the joint, in which the first and second members 3, 4 can move apart (as shown in Figures 3 and 5).

Non-linear edge 3a of first member 3 is also offset from divider plate 1, in the direction, perpendicular to the longitudinal axis of the joint, in which the first and second members 3, 4 can move apart.

Divider plate 1 comprises apertures 6 along its length at intervals. The apertures 6 are adapted to receive dowel plates 7. On the side of the divider plate 1 which is not attached to first support 2, the dowel plates 7 are encased in dowel sleeves 12, which allow movement of the concrete relative to the dowel plates 7.

As shown in Figure 6, the sleeves 12 have gaps 14 on each side of the dowel plates 7, in order to allow movement in the direction parallel to the longitudinal axis of the joint. In the embodiment shown, longitudinal width B of gaps 14 in the dowel sleeves 12 is larger than longitudinal width Aof the corresponding gaps 13 in the surface pattern.

Divider plate 1 has a U-shaped fold 8 along its lower edge.

Anchor means 9, 10 extend out from the first and second supports 2, 5 in the general direction where, in use, the concrete would be poured.

In use, the apparatus will be used as a joint between concrete floor slab panels.

Once the spaces for casting concrete on either side of the apparatus have been set up, i.e. the formwork has been set up, concrete is poured into the spaces, defined by one or more divider plates. Commonly, three of the four sides of a slab panel are set up with formwork, after which the casting of concrete is started; the fourth face is closed off last. After the concrete has been poured, it is allowed to cure.

The first and second members 3,4 can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint, in the absence of any movement or with only a minimal amount of movement in the direction perpendicular to the longitudinal axis of the joint. If the forces acting on the concrete slab panels work mainly in the longitudinal direction, the joint can therefore move e.g. from a position as shown in Figure ito one as shown in Figure 2. If the direction of the required movement in the longitudinal direction can be predicted, the joint may be set up in a way which allows the maximum amount of movement in the desired direction, for example by starting out from a position where the gaps 13 are present on only one side of the peaks in the surface pattern, as shown in Figure 2.

The joint can also open up in the direction perpendicular to the longitudinal axis of the joint, if the concrete slab panels move apart in this direction. In that case, as the concrete on either side of the divider plate 1 shrinks, the first and second members 3, 4 (and their associated supports) move apart to leave an elongate non-linear gap 11 which is as deep as the members 3, 4, as shown in Figure 3. This gap 11 is offset from the gap which opens up between the supports 2, 5, which extends down to the subbase between the two shrinking concrete slab panels and is defined along one face by the divider plate 1. Therefore the gap which extends down to the subbase between the two shrinking concrete slab panels is covered by second member 4 at the surface, which prevents the ingress of debris and vermin.

Moreover, surface gap 11 does not impart shocks to wheels passing over it, because the non-linear edges 3a, 4a of gap 11 are shaped and dimensioned such that for wheels of a specific width or greater (e.g. from 65 mm), when traversing gap 11, e.g. from first member 3 to second member 4, the wheel is already supported by the peaks in the edge of second member 4 before losing contact with the mating peaks in the edge of first member 3.

If the joint opens up in the direction perpendicular to the longitudinal axis of the joint, the first and second members 3, 4 have the ability to move relative to one another in a direction substantially parallel to the longitudinal axis of the joint even further, and hence the joint can accommodate even larger movements in this direction.

Figures 7 to 10 show a second embodiment of the apparatus of the invention. In this embodiment, in use the first member 3 and second member 4 extend vertically downward along adjacent vertical faces of the concrete floor slab panels. The first and second members may extend all the way downward to the subbase. In that case, the first and second members 3, 4 are present in the form of full-depth corrugated forms.

As in the case of the first embodiment, second member 4 is arranged to mate with first member 3 along non-linear edges 3a, 4a. Non-linear edges 3a, 4a each form a trapezoidal surface pattern. The surface pattern formed by non-linear edges 3a, 4a when the first and second members 3, 4 abut one another contains gaps 13 in between the members 3, 4. The gaps 13 in the surface pattern are arranged in such a way that, when the first and second members 3, 4 abut one another, the members 3, 4 can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint. This is clearly shown in Figures Band 9. Figure 8 shows the trapezoidal surface pattern with members 3, 4 in a position where the gaps 13 on the sides of each peak are of equal size. Figure 9 shows the situation where the first and second members 3, 4 have moved relative to one another in a direction substantially parallel to the longitudinal axis of the joint, which results in the gaps 13 being present on only one side of each peak in the surface pat±ern.

The second embodiment may also contain apertures, dowel plates, dowel sleeves and anchor means in a similar manner as described for the first embodiment.

Similarly to the first embodiment, in use as a joint between concrete floor slab panels, the first and second members 3, 4 can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint, in the absence of any movement or with only a minimal amount of movement in the direction perpendicular to the longitudinal axis of the joint. If the forces acting on the concrete slab panels work mainly in the longitudinal direction, the joint can therefore move e.g. from a position as shown in Figure 8 to one as shown in Figure 9. lIthe direction of the required movement in the longitudinal direction can be predicted, the joint may be set up in a way which allows the maximum amount of movement in the desired direction, for example by starting out from a position where the gaps 13 are present on only one side of the peaks in the surface pattern, as shown in Figure 9.

The joint can also open up in the direction perpendicular to the longitudinal axis of the joint, if the concrete slab panels move apart in this direction. In that case, as the concrete on either side of the first and second members 3, 4 shrinks, the members move apart to leave an elongate non-linear gap 11, as shown in Figure 10.

Claims

Claims 1. Apparatus for forming a joint between concrete floor slab panels, the apparatus comprising: first and second members which are securable to adjacent concrete floor slab panels and which are arranged to mate with one another along non-linear edges, which non-linear edges, in use, define the edges of the adjacent concrete floor slab panels at their upper surfaces, wherein the surface pattern formed by the non-linear edges when the first and second members abut one another contains one or more gaps in between the members, the gaps in the surface pattern being arranged in such a way that, when the first and second members abut one another, the members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint.
2. The apparatus of claim 1, wherein the apparatus further comprises: first and second supports, the first support being attached to or attachable to the first member, and the second support being attached to or attachable to the second member, wherein, in use, at least part of each of the first and second supports extends vertically downward along adjacent vertical faces of the concrete floor slab panels.
3. The apparatus of claim 2, further comprising a divider plate for defining a boundary between adjacent concrete floor slab panels, wherein the first support is attached to and/or supported by the divider plate.
4. The apparatus of claim 3, wherein the second support is attached to the divider plate with yieldable fixings.
5. The apparatus of any one of claims 2 to 4, wherein the first support comprises a facing side which faces the second support, and the non-linear edge of the first member is offset from the facing side of the first support in the direction, perpendicular to the longitudinal axis of the joint, in which the first and second members can move apart, so that, when in use between two shrinking concrete slab panels, any gap which opens up between the first and second members in the direction perpendicular to the longitudinal axis of the joint is offset from any gap which opens up between the supports in the direction perpendicular to the longitudinal axis of the joint.
6. The apparatus of claim 1, wherein, in use, at least part of the first and second members extends vertically downward along adjacent vertical faces of the concrete floor slab panels.
7. The apparatus of claim 6, wherein, in use, the first and second members extend vertically downward to the subbase.
8. The apparatus of claim 6, further comprising a divider plate for defining a boundary between adjacent concrete floor slab panels, wherein the first member is attached to and/or supported by the divider plate.
9. The apparatus of any one of the preceding claims, wherein the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is at least 2 mm.
10. The apparatus of claim 9, wherein the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is at least 5 mm.
11. The apparatus of claim 10, wherein the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is at least 10 mm.
12. The apparatus of any one of the preceding claims, wherein the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is up to 50 mm.
13. The apparatus of any one of the preceding claims, wherein the distance by which the first and second members can move relative to one another in a direction substantially parallel to the longitudinal axis of the joint when the first and second members abut one another is from 3 mm up to 40 mm.
14. The apparatus of any one of the preceding claims, wherein the non-linear edges of the first and second members form a surface pattern in the shape of a repeating pattern.
15. The apparatus of claim 14, wherein the non-linear edges of each of the first and second members form a surface pattern in the shape of a waveform.
16. The apparatus of claim 15, wherein the non-linear edges of each of the first and second members form a surface pattern in the shape of a sinusoidal waveform, a trapezoidal waveform, or a triangular waveform.
17. The apparatus of any one of claims 14 to 16, wherein the repeating surface pattern has a wavelength which is set up, for wheels and/or vehicle tyres above a certain width, such that in use when a wheel and/or vehicle tyre traverses a gap between the non-linear edges of the first and second members, as a wheel and/or vehicle lyre departs from one member, it is already in contact with the other member.
18. An apparatus for forming a joint between concrete floor slab panels, the apparatus being substantially as described herein with reference to the accompanying drawings.
19. A concrete floor comprising the apparatus according to any one of claims 1-18.
20. A method of manufacturing a concrete floor, comprising the steps of (i) setting up the apparatus according to any one of claims 1-18 to form at least part of an edge of a space for casting concrete; and (U) casting concrete on at least one side of the apparatus.
21. The method of claim 20, wherein in step (U), the concrete is cast on both sides of the apparatus, either simultaneously or sequentially.
22. A method of manufacturing a concrete floor, comprising the steps of (I) setting up the apparatus according to claim 3 or any claim dependent thereon, or claim 8 or any claim dependent thereon, to form at least part of an edge of a space for casting concrete; (U) casting concrete on one side of the apparatus; (Ui) removing the divider plate; and (iv) casting concrete on the other side of the apparatus.
23. A concrete floor formed by the method of any one of claim 20-22.
24. A method of manufacturing a concrete floor, the method being substantially as described herein with reference to the accompanying drawings.