Gap former for concrete slabs

Abstract

A void former for use in a concrete slab including a prefabricated floor. The void former includes: a first hollow body having an enclosed side portion, an enclosed top portion, and an open bottom portion of the same height, where an inner surface of the top portion includes a plurality of integral reinforcing ribs; means for embedding and anchoring the first hollow body to the prefabricated floor; and means for ensuring that the first hollow body is horizontally seated on the prefabricated floor. The means for embedding and anchoring the first hollow body in turn comprise a plurality of L-shaped legs projecting downwardly from the periphery of the open bottom portion, and the means for seating and leveling the first hollow body comprise a plurality of protrusions extending laterally from the enclosing side around the periphery of the open bottom portion.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of building construction, in particular to a void former for use in forming a construction element such as a concrete panel. BACKGROUND

[0002] The use of precast concrete panels in the construction of floors of buildings is well known in the field of building construction, as is the use of void formers to create voids within the panels to reduce the volume of concrete required to be poured during the casting process by about 20% to 30%, which in turn reduces the weight of the panel and therefore the cost of the panel, while still maintaining the structural strength of the panel.

[0003] Examples of known void formers (void formers are also known as cavity formers) are those disclosed in documents WO 2017 / 095263 A2, WO 2005 / 108701 Al, AU 2018202136 Bl, AU 2019101738 B4 and AU 2021286454 Al.

[0004] WO 2017 / 095263 A2 relates to a permanent formwork void former comprising a hollow body provided with spatial position fixing means and comprising a conical bearing foot and at least one box-like member in the shape of a truncated pyramid, which is open at a large base end and has passages at the corners and reinforcing ribs for stiffening the top side.

[0005] WO 2005 / 108701 Al discloses a cavity former for forming one or more cavities in a concrete panel, and the cavity former comprises a hollow body around which the poured concrete flows during use of the former and which subsequently solidifies to form a concrete panel in which the hollow body defines a cavity.

[0006] AU 2018202136 Bl relates to a collapsible void former for use in the manufacture of reinforced concrete objects such as panel soffits, the collapsible void former comprising a shaped body having a volume and an open base generally of moulded plastic.

[0007] AU 2019101738 B4 relates to a void forming module comprising at least one hollow body having at least one upper surface and a lower abutment peripheral edge and at least one shaped bearing extending from the at least one upper surface and terminating at a level coplanar with the lower abutment peripheral edge.

[0008] AU 2021286454 Al relates to a void filler system for use in forming a concrete blank, the void filler system comprising a hollow void former having a body comprising four side walls, a top wall and an open bottom, the void former configured to be split into a plurality of hollow sections.

[0009] All of the above examples of void formers are made from a suitable plastic or thermoplastic by injection moulding. Notably, all of these examples have complex, fine multi-part structural features. Examples of fine features are the internal legs or supports present in several of the previously described void formers, which can be integral with or separately provided from continuous flanges, heavy internal ribs and even mechanical features for aligning or locking multiple void formers disposed adjacent to one another.

[0010] Whilst such structural features are undoubtedly useful, it is to be expected that the manufacture and, in turn, purchase of such structural features is more expensive due to the higher costs associated with the machining of the injection mould by virtue of the fine mechanical design, the number of unique parts and the larger amount of raw material used in their manufacture.

[0011] In view of the rising cost of building materials, it is a desire and object of the present invention to provide an alternative void former which is simpler to manufacture, more material efficient and, therefore, more cost effective without compromising the structural strength of the concrete blank. SUMMARY

[0012] In a first aspect, the present invention provides a void former for use in a concrete blank comprising a precast floor.

[0013] The void former comprises a first hollow body having enclosed side portions, an enclosed top portion and an open bottom portion of the same height, wherein the inner surface of the top portion comprises a plurality of integral reinforcing ribs, means for embedding and anchoring the first hollow body to the precast floor of the concrete blank, and means for ensuring that the first hollow body is seated horizontally on the precast floor of the concrete blank.

[0014] The means for embedding and anchoring the first hollow body comprises a plurality of L-shaped legs projecting downwardly from the periphery of the open bottom portion.

[0015] The means for seating and levelling the first hollow body comprises a plurality of protrusions extending laterally from the enclosed side portions around the periphery of the open bottom portion.

[0016] In the void former according to the first aspect of the invention, the enclosed side portions have a thickness of 2.0 mm + / - 0.1 mm.

[0017] In the void former according to the first aspect of the present application, the L-shaped leg preferably has a length of 20.0 mm.

[0018] Alternatively, the plurality of L-shaped legs is preferably integral with the first hollow body.

[0019] As a further alternative, the plurality of protrusions is also preferably integral with the first hollow body.

[0020] In the void former according to the first aspect of the present application, the enclosing top portion of the first hollow body preferably has an outer surface with rounded / rounded-off / curved edges.

[0021] In the void former according to the first aspect of the present application, the first hollow body preferably has a square frustum shape, wherein the enclosing sides converge upwards or are inclined with respect to the open bottom portion.

[0022] Alternatively, the enclosing sides of the first hollow body converge or are inclined with respect to the open bottom portion at an angle of 106.05°.

[0023] In the void former according to the first aspect of the present application, the first hollow body is preferably made of a polymeric material.

[0024] As an alternative, the polymeric material used can be recycled polypropylene.

[0025] In the void former according to the first aspect of the present application, the enclosing top portion of the first hollow body can receive a second hollow body having enclosing sides, an enclosing top portion and an open bottom portion corresponding to the enclosing top portion of the first hollow body for extending the height of the void former.

[0026] In the void former according to the first aspect of the present application, the plurality of integral reinforcing ribs preferably comprises longitudinal reinforcing ribs and weft reinforcing ribs intersecting in the center of the inner surface of the enclosing top portion of the first hollow body.

[0027] In the void former according to the first aspect of the present application, the second hollow body is preferably made of a polymeric material.

[0028] Alternatively, the polymeric material can be recycled polypropylene.

[0029] In a second aspect, the present application provides a precast concrete floor slab having an upper surface and a lower surface, longitudinal edges and weft edges and having a thickness in the range of 50 mm to 100 mm.

[0030] The precast concrete floor slab comprises a first reinforcement mesh embedded within the floor slab, a plurality of lattice beams along the longitudinal length of the floor slab, wherein the lower chord of each lattice beam is attached to the reinforcement mesh and embedded within the floor slab and the upper chord protrudes from the upper surface of the floor slab, a plurality of L-shaped dowels having one end attached to the reinforcement mesh and embedded within the floor slab and the other end protruding from the longitudinal edges of the floor slab, and a plurality of void formers according to the first aspect of the present invention embedded and anchored onto the upper surface of the floor slab.

[0031] In the precast concrete floor slab according to the second aspect of the present invention, the plurality of void formers embedded and anchored onto the upper surface of the floor slab are preferably positioned on both sides of each lattice beam along the longitudinal length of the floor slab.

[0032] Additionally, the precast concrete floor slab according to the second aspect of the present invention can comprise one or more post-tensioning ducts positioned longitudinally and latitudinally along the length and width of the upper surface of the concrete floor slab.

[0033] The precast concrete floor slab according to the second aspect of the present invention can form part of a concrete slab blank which further comprises a second reinforcement mesh seated on top of the floor slab and attached to the upper chords of the plurality of lattice beams protruding from the upper surface of the floor slab and a concrete top layer cast on the steel reinforcement mesh and the floor slab.

[0034] The use of the void formers according to the first aspect of the present invention in the precast concrete floor slab according to the second aspect of the present invention for use in the manufacture of concrete slab blanks alleviates the problem of cost increase of construction materials without sacrificing structural strength and integrity. BRIEF DESCRIPTION OF DRAWINGS

[0035] Referring to the drawings, the present invention is illustrated by, but is not limited to, the following description of embodiments given by way of example only, in which:

[0036] Figure 1A The void formers for use in concrete slab blanks according to the first aspect of the present invention are illustrated in isometric view.

[0037] Figure 1B The void formers for use in concrete slab blanks according to the first aspect of the present invention are illustrated in plan view.

[0038] Figure 1C The void formers for use in concrete slab blanks according to the first aspect of the present invention are illustrated in cross-sectional view taken along line A-A of the plan view.

[0039] Figure 1DThe illustration shows another cross-sectional view of a void former for use in a concrete slab, according to the first aspect of the invention, taken along line BB of the plan view.

[0040] Figure 2A A perspective view illustrates a height extension for a void former used in a concrete slab according to a first aspect of the invention.

[0041] Figure 2B A plan view illustrates a height extension for a void former used in a concrete slab according to a first aspect of the invention.

[0042] Figure 2C A side view illustrates a height extender for a void former used in a concrete slab according to a first aspect of the invention.

[0043] Figure 2D The figure shows a cross-sectional view of the height extension of the void former for use in a concrete slab, taken along line AA of the plan view, according to the first aspect of the invention.

[0044] Figure 3A A perspective view illustrates the use of a void-forming device for use in a concrete slab according to the first aspect of the invention. Figures 2A-2D The height extender.

[0045] Figure 3B A plan view illustrates the use of a void-forming device according to the first aspect of the invention for use in concrete slabs. Figures 2A-2D The height extender.

[0046] Figure 3C The illustration shows a void-forming device for use in concrete slabs, taken along line AA of a plan view. Figures 2A-2D A cross-sectional view of the height extender.

[0047] Figure 3D The illustration shows a void-forming device for use in concrete slabs, taken along line BB of a plan view. Figures 2A-2D A cross-sectional view of the height extender.

[0048] Figure 4A A perspective view illustrates a precast concrete base plate having a plurality of void formers according to a first aspect of the invention on its upper surface.

[0049] Figure 4B The diagram is presented in exploded view format. Figure 4A The diagram shows a three-dimensional view of the precast concrete base slab.

[0050] Figure 5 A cast concrete slab with a plurality of void formers according to the first aspect of the application on the upper surface of a precast concrete floor slab is illustrated in perspective view. DETAILED DESCRIPTION

[0051] Figures 1A-1D A void former 1 according to the first aspect of the application for use in a concrete slab is illustrated in perspective view, plan view and cross-sectional view.

[0052] The void former comprises a first hollow body 10 having enclosing side portions 11, enclosing top portions 12 and an open bottom portion 13 of the same height, means for embedding and anchoring the first hollow body 10 to the precast floor slab of the concrete slab and means for ensuring that the first hollow body 10 is seated horizontally on the precast floor slab of the concrete slab.

[0053] The enclosing side portions 11 have a thickness of 2.0 mm, with a tolerance of + / - 0.1 mm, which is thin enough to give the first hollow body a degree of flexibility and to allow coring work to be easily performed on the concrete slab to facilitate the installation of conduits, pipes, electrical ducts, etc.

[0054] The means for embedding and anchoring the first hollow body 10 comprise, in turn, a plurality of L-shaped legs 14 that project downward from the periphery of the open bottom portion 13 of the first hollow body 10.

[0055] The purpose of the plurality of L-shaped legs 14 is to embed and anchor the first hollow body 10 to the upper surface of the precast concrete floor slab so that the void former 1 is able to support loads without deforming or cracking after it has been embedded on the concrete floor slab.

[0056] This is achieved by the fact that when each L-shaped leg 14 is embedded and anchored to the precast concrete floor slab, there will be a resistance between the L-shaped leg 14 and the surrounding concrete after the concrete has cured. When there is a point load on the slab, the force applied downward will be distributed and spread over the entire surface of the enclosing side portions 11 and the enclosing top portions 12 of the first hollow body 10. The force applied downward creates a resultant force, which is then counteracted by the resistance that exists between the L-shaped legs 14 and the surrounding concrete. This is similar to how a simple arch bridge supports loads. A simple arch bridge is anchored at each end of its span, each end of the span is connected to each other by arch ribs, and when there is a load that is transverse to the span of the simple arch bridge, the action of the load is transmitted and distributed to the arch ribs. In the void former according to the first aspect of the application, the enclosing side portions 11 and the enclosing top portions 12 of the first hollow body 10 combine to be equivalent to the arch ribs of a simple arch bridge, while the L-shaped legs 14 are equivalent to the anchor points at the two ends of the arch ribs.

[0057] Due to the structural requirements according to the constructional engineering, the precast concrete floor slab usually has a thickness between 50 mm and 100 mm, the length of the L-shaped leg in the void former according to the first aspect of the present invention is preferably 20 mm.

[0058] In Figure 1A and Figure 1B the void former 1 is illustrated with L-shaped legs 14 at each corner of the first hollow body 10 and with another L-shaped leg 14 at the middle of each enclosing side 11, which essentially means that the L-shaped legs 14 are spaced at uniform intervals. The number of L-shaped legs 14 included depends more on the cost, and the present invention is by no means limited to the configuration shown and described herein. For example, more L-shaped legs spaced at different intervals can be included without affecting the effectiveness of the present invention.

[0059] Finally, the means for seating and levelling the first hollow body 10 on the floor slab of the concrete slab blank comprises a plurality of protrusions 15 protruding or extending laterally from the enclosing side 11 around the circumference of the open bottom portion 13 to the first hollow body 10.

[0060] The purpose of the plurality of protrusions 15 is to ensure that the first hollow body 10 embedded on the upper surface of the precast concrete floor slab is level with the upper surface of the floor slab by serving as a visual indicator. Once the first hollow body 10 is embedded on the upper surface of the precast concrete floor slab, as long as the plurality of protrusions 15 is visible, it means that the first hollow body 10 is actually level with the upper surface of the precast concrete floor slab.

[0061] Generally, the goal is to ensure that the thickness of the concrete top layer cast on the enclosing top portion of the void former is 75 mm. The concrete top layer with a thickness of 75 mm will be sufficient to withstand the punch shear force generated by the point load acting on the concrete slab blank, such as the tires of a vehicle parked on the concrete slab blank. Therefore, any unevenly embedded void former will result in an inconsistent thickness of the top layer, and thus it is necessary to ensure that the void former is embedded horizontally on the precast concrete floor slab.

[0062] By ensuring that each of the plurality of void formers is embedded horizontally on the upper surface of the precast concrete floor slab, the plurality of levelling protrusions 15 provides a simple solution to the problem: the newly poured concrete on the precast concrete floor slab can be ensured to solidify with a uniform thickness, simply by visual observation and without the need for any specialized tools and jigs.

[0063] The advantage of using the plurality of levelling protrusions 15 instead of a continuous flange around the circumference of the open bottom portion 13 is that the plurality of levelling protrusions 15 is still able to provide the same effect as the continuous flange, while having the advantage of being more material efficient and less tooling cost.

[0064] In Figure 1A and Figure 1B the void former 1 is illustrated with levelling tabs 15 between each pair of L-shaped legs 14. The number of levelling tabs 15 included depends on cost and the present invention is in no way limited to the configuration of levelling tabs shown and described herein. For example, more levelling tabs can be included spaced at different intervals without affecting the effectiveness of the present invention.

[0065] The void former 1 according to the first aspect of the present invention is manufactured by injection moulding, wherein the plurality of L-shaped legs 14 and the plurality of levelling tabs 15 are integrally formed with the first hollow body 10 during manufacture.

[0066] However, the present invention is not limited to this configuration and it is envisaged that the first hollow body 10 can be manufactured without the plurality of L-shaped legs 14 and / or the plurality of tabs 15. The L-shaped legs 14 and levelling tabs 15 can in fact be manufactured as separate pieces that are attached to the first hollow body 10 by means of mounting clips or slots. This allows for different lengths of L-shaped legs and levelling tabs to be incorporated when required.

[0067] As shown in Figures 1A-1D the first hollow body 10 has a square frustum shape with the enclosing side 11 converging upwards or sloping with respect to the open base portion 13. The enclosing side 11 of the first hollow body 10 is specifically sloped at an angle of 106.2° with respect to the open base portion 13 to enable the void former 1 according to the first aspect of the present invention to support a point load of 100 kg without deforming or cracking by ensuring that the resultant force of a given point load pressing down on the enclosing top portion 12 of the first hollow body 10 does not exceed the resistance force acting on the L-shaped legs 14 when the void former 1 is embedded in a precast concrete floor slab.

[0068] The enclosing top portion 12 of the first hollow body 10 has an outer surface with rounded (i.e. rounded or curved) edges to facilitate the flow of freshly poured concrete during the casting of the top layer of the concrete slab. The rounded edges of the outer surface also enable the plurality of void formers 1 to be easily stacked to save space during transportation or storage as the first hollow body 10 can be received by its open base portion 13 by another identical first hollow body 10.

[0069] As in Figure 1C and Figure 1DAs can be seen in the cross-sectional view of the void former 1 in Fig. 1, the inner surface of the top portion 12 of the first hollow body 10 comprises integral longitudinal stiffening ribs 16 and integral weft stiffening ribs 17, which intersect in the centre of the enclosed inner surface of the top portion 12 to increase the stiffness of the enclosed top portion 12, which eventually will have to carry the weight of the top layer of the concrete slab blank and thereafter, when the construction is completed, the weight of any personnel or vehicle traffic.

[0070] Since the void former 1 according to the first aspect of the present invention is manufactured by injection moulding, the longitudinal stiffening ribs 16 are formed as an integral structure on the inner surface of the top portion 12 of the first hollow body 10.

[0071] Although the void former 1 of the first aspect of the present invention is shown in Figures 1A-1D Fig. 1 and also described herein as having a single longitudinal stiffening rib 16 and a single weft stiffening rib 17, the present invention is clearly not limited to such a configuration.

[0072] It is conceivable that in another embodiment of the present invention additional longitudinal stiffening ribs and / or weft stiffening ribs can be incorporated to increase the stiffness of the first hollow body 10 and thus its load carrying capacity.

[0073] As an example, the first hollow body 10 of the void former 1 according to the first aspect of the present invention having a square frustum shape preferably has an enclosed top portion 12 with an area of 0.4 m x 0.4 m and an open bottom portion 13 with a “footprint” of 0.47 m x 0.47 m.

[0074] The void former 1 according to the first aspect of the present invention is made of a polymer material which is very suitable for injection moulding. An example of a suitable polymer material would be polypropylene (PP), and as an economic and ecological measure, recycled polypropylene can be used since polypropylene is widely used for disposable containers, bottles and packaging materials.

[0075] The suitability of using recycled polypropylene depends on its mechanical properties, in particular its tensile strength at break at 23°C of 18 MPa, which means that the recycled polypropylene can withstand a maximum tensile or compressive load of 18 N / mm 2 before it deforms and breaks.

[0076] For a concrete slab blank having a concrete top layer with a thickness of 75 mm, based on the concrete having a density of 2,500 kg / m 3The downward force F acting on the first hollow body 10 is calculated as follows, with the assumption of an average density of 2.4 kg / dm3, with a hollow body 10 having an "footprint" of 0.47 m x 0.47 m of the open bottom portion 13 and having the enclosing side portion 11 inclined at an angle of 106.2° with respect to the open bottom portion 13.

[0077] The resultant R1 of the downward force F acting on the first hollow body 10 is calculated as follows.

[0078] Since the tensile strength at break of polypropylene is 18 N / mm 2 , with the assumption that each L-shaped leg 14 has a length of 20 mm and a width of 25 mm, the resistance is calculated as follows.

[0079] This resistance is greater than the resultant R1 of 0.40 kN, and verifies the ability of the first hollow body 10 to withstand the weight of a 75 mm thick concrete layer by means of the resistance of each L-shaped leg 14 anchored to the floor of the concrete slab.

[0080] As Figure 1A and Figure 1B illustrated in and described herein, the void former 1 comprises a total of 8 L-shaped legs, which will be sufficient to withstand a load of 6000 kg (such as a vehicle parked on the concrete slab), which will exert a downward force of 60 kN. This downward force, when distributed over the 8 L-shaped legs, corresponds to a load of 7.5 kN per L-shaped leg, and the resultant R2 of the downward force acting on the hollow body is calculated as follows.

[0081] This does not obviously exceed the resistance of each L-shaped leg, previously calculated as 9.0 kN, thus verifying the ability of the hollow body to withstand a load of 6,000 kg.

[0082] Since it is envisaged that, as an economic measure, the void former 1 according to the aspect of the present invention will be manufactured in individual and standard sizes, the height of the void former according to the first aspect of the present invention can easily be increased by means of the height extender 2 if the construction work requires thicker concrete slabs, which in turn require a higher cavity to be formed within the slab.

[0083] Figure 2A The height extender 2 for the void former 1 for use in a concrete slab according to the first aspect of the present invention is illustrated in perspective view.

[0084] The height extender 2 includes a second hollow body 20 having a closed side portion 21, a closed top portion 22, and an open bottom portion 23, wherein the shape and size of the open bottom portion 23 of the second hollow body 20 correspond to the shape and size of the closed top portion 22 of the first hollow body 20, such that the second hollow body 20 can be received above the closed top portion 22 of the first hollow body 20.

[0085] Similar to the void forming device 1 according to the first aspect of the invention, the sealing side 21 also has a thickness of 2.0 mm, wherein the tolerance is + / - 0.1 mm.

[0086] In order for the height extender 2 to correspond to the gap former 1 and be received by the gap former 1, the height extender 2 also has a square truncated shape, wherein the enclosed side 21 of the height extender 2 is also inclined at an angle of 106.2° relative to the open bottom portion 23.

[0087] Similar to the void former 1 according to the first aspect of the invention, the enclosed top portion 22 of the second hollow body 20 also has an outer surface with rounded edges to facilitate the flow of newly poured concrete during the pouring of the top layer of the concrete slab. The rounded edges of the outer surface also allow multiple height extenders 2 to be stacked for transport or storage, as the second hollow body 20 can receive another identical second hollow body 20 through its open bottom portion 23.

[0088] Similarly, the height extender 2 is also made of a polymeric material such as polypropylene by injection molding. Therefore, the height extender can also be made of recycled polypropylene.

[0089] Figures 3A-3D The illustration shows how the height extender 2 can be used with the void former 1 according to a first aspect of the invention.

[0090] The height extender 2 is simply stacked on top of the void former 1 according to the first aspect of the invention, as follows: Figures 3A-3D As shown in the figure. Since the shape and size of the open bottom portion 23 of the second hollow body 2 corresponds to the shape and size of the closed top portion 12 of the first hollow body 10, the second hollow body 20 will sit firmly on top of the first hollow body 20, thus extending the height of the void former 1.

[0091] Since both the sealing side 11 of the first hollow body 10 and the sealing side 21 of the second hollow body 20 are inclined at the same angle (i.e., 106.2° relative to their respective open bottom portions), when the height extender 2 is stacked on the void former 1, the sealing side of the combined structure forms a continuous and uninterrupted surface, such as... Figures 3A-3DIt can be seen in the image.

[0092] Although both the gap former 1 and its height extender 2 are shown and described herein as having a square frustum shape, the invention is certainly not limited to this shape. In another embodiment of the invention, the gap former 1 and its height extender 2 may have a circular frustum shape, provided that the enclosing sides are inclined at an angle of 106.2° relative to their open bottom portions.

[0093] According to a first aspect of the invention, a void forming device 1 (and its height extender 2—if necessary) is used in the manufacture of a concrete slab, which mainly comprises a precast concrete base slab and a reinforcing mesh layer, on which a concrete top layer is poured and formed. The void forming device 1 and its height extender 2 are introduced during the manufacture of the concrete slab and are components of the precast concrete base slab.

[0094] Figure 4A A perspective view illustrates a precast concrete base slab 4 according to a second aspect of the present invention, which is manufactured using a void former 1 according to a first aspect of the present invention. Figure 4B yes Figure 4A An exploded view of the precast concrete base slab 4 shows more clearly the various components included in the precast concrete base slab.

[0095] The precast concrete base plate 4 according to the second aspect of the invention is basically a conventional concrete base plate 40, which includes an upper surface 40a, a lower surface 40b, a longitudinal edge 40c and a lateral edge 40d and can be manufactured to a thickness of 50 mm to 100 mm according to user requirements.

[0096] According to a second aspect of the present invention, the precast concrete base slab 4 comprises the following components:

[0097] i) Reinforcing mesh 41, which is embedded in the base plate 40.

[0098] ii) A plurality of lattice beams 42 are positioned along the longitudinal length of the base plate 40, wherein the lower chord of each lattice beam is attached to the reinforcing mesh 41 and embedded in the base plate 40, and the upper chord protrudes from the upper surface 40a of the base plate 40.

[0099] iii) A plurality of L-shaped pins 43, which serve as shear connectors, each L-shaped pin 43 having one end attached to the reinforcing mesh 41 and embedded within the concrete base plate 40, and another end protruding from the longitudinal edge 40c of the base plate 40.

[0100] iv) A plurality of void forming devices 1 according to the first aspect of the invention, the plurality of void forming devices 1 being embedded and anchored to the upper surface 40a of the concrete base plate 40.

[0101] In addition, if required, the precast concrete slab 4 can include post-tensioning. This is achieved by including post-tensioning ducts 44a, 44b positioned longitudinally and latitudinally along the length and width of the upper surface of the concrete slab 40.

[0102] During the manufacture of the precast concrete slab 4, prior to pouring the concrete, the reinforcing mesh 41, the plurality of lattice beams 42 and the plurality of L-shaped dowels 43 are welded together to form the internal structure of the precast concrete slab 40.

[0103] Thereafter, prior to the concrete setting, a plurality of void formers 1 according to the first aspect of the application are anchored to the reinforcing mesh 41 and embedded on the upper surface 40a of the concrete slab 40. The plurality of levelling tabs 15 on each void former 1 act as visual indicators to ensure that each void former 1 has been embedded at the same level on the upper surface 40a of the concrete slab 40.

[0104] In the case where a greater thickness of concrete slab is required, a height extender can be used with the void formers to form a higher cavity.

[0105] The plurality of void formers are positioned in a matrix or array determined by the position of the plurality of lattice beams 42 to ensure that the cavities formed by each void former are evenly distributed and / or spaced apart.

[0106] If post-tensioning is required, then a plurality of post-tensioning ducts 44a, 44b can then be anchored to the upper surface 40a of the precast concrete slab 40 between the rows and columns of the array of void formers 1 longitudinally and latitudinally along the length and width of the upper surface of the concrete slab 40.

[0107] Figure 5 Figure illustrates a perspective view of a concrete slab (5) manufactured from a precast concrete slab 4 according to the second aspect of the application.

[0108] The concrete slab 5 primarily comprises:

[0109] i) a precast concrete slab 4 according to the second aspect of the application,

[0110] ii) a second reinforcing mesh 45 seated on top of the precast concrete slab 4, and

[0111] iii) a concrete top layer 51 of a desired thickness cast on the steel reinforcing mesh 45 and the precast concrete slab 4.

[0112] A second reinforcement mesh 45 is attached to the upper chord of the lattice beam 42 that protrudes from the upper surface 40a of the precast concrete base slab 40 and will eventually be embedded in the concrete top layer 51 when the concrete used to form the top layer 51 is poured over the precast concrete base slab 4 and the second reinforcement mesh 45 to the desired thickness.

[0113] As can be seen from the foregoing, the present application provides an effective solution to the rising cost of construction materials by designing a simple and material efficient void former, while maintaining good structural strength and having features that help to manufacture a concrete mat of consistent thickness.

[0114] The present application is not limited to what has been disclosed herein, as the description is merely for the purposes of exemplification and other modifications are readily apparent to those skilled in the art without departing from the scope of the application.

Claims

1. A void former (1) for use in a concrete slab including a precast base plate, the void former comprising: The first hollow body (10) has a sealed side portion (11), a sealed top portion (12), and an open bottom portion (13) of the same height, wherein the inner surface of the sealed top portion includes a plurality of integral reinforcing ribs (16, 17). A means for embedding and anchoring the first hollow body (10) to the precast base plate of the concrete slab, and Device for ensuring that the first hollow body (10) sits horizontally on the precast base plate of the concrete slab. Its features are, The device for embedding and anchoring the first hollow body (10) includes a plurality of L-shaped legs (14) projecting downward from the periphery of the open bottom portion (13), and The means for seating and leveling the first hollow body (10) includes a plurality of protrusions (15) extending laterally from the enclosed side around the periphery of the open bottom portion (13).

2. The void forming device (1) according to claim 1, wherein, The enclosure side has a thickness of 2.0 mm + / - 0.1 mm.

3. The void forming device (1) according to claim 1 or claim 2, wherein, The L-shaped support leg (14) has a length of 20.0 mm.

4. The void forming device (1) according to any of the preceding claims, wherein, The plurality of L-shaped legs (14) are integrated with the first hollow body (10).

5. The void forming device (1) according to any of the preceding claims, wherein, The plurality of protrusions (15) are integrated with the first hollow body (10).

6. The void forming device (1) according to any of the preceding claims, wherein, The enclosed top portion (12) of the first hollow body (10) has an outer surface with rounded / rounded / curved edges.

7. The void forming device (1) according to any one of the preceding claims, wherein, The first hollow body (10) has a square truncated shape, wherein the enclosed side (11) converges upward or is inclined relative to the open bottom portion (13).

8. The void forming device (1) according to claim 6, wherein, The enclosed side (11) of the first hollow body (10) converges or tilts at an angle of 106.05° relative to the open bottom portion (13).

9. The void forming device according to any one of the preceding claims, wherein, The plurality of integral reinforcing ribs include longitudinal reinforcing ribs (16) and latitudinal reinforcing ribs (17) that intersect at the center of the inner surface of the enclosed top portion (12) of the first hollow body (10).

10. The void forming device (1) according to any one of the preceding claims, wherein, The first hollow body (10) is made of polymer material.

11. The void forming device (1) according to claim 9, wherein, The polymer material is recycled polypropylene.

12. The void forming device (1) according to any one of the preceding claims, wherein, The top enclosure portion (12) of the first hollow body (10) is capable of receiving a second hollow body (20) having a side enclosure portion (21), a top enclosure portion (22) and an open bottom portion (23) corresponding to the top enclosure portion (12) of the first hollow body (10) for extending the height of the void former.

13. The void forming device (1) according to claim 12, wherein, The second hollow body (20) is made of polymer material.

14. The void forming device (1) according to claim 13, wherein, The polymer material is recycled polypropylene.

15. A precast concrete base slab (4), said precast concrete base slab (4) having an upper surface (40a) and a lower surface (40b), a longitudinal edge (40c) and a lateral edge (40d) and having a thickness in the range of 50 mm to 100 mm, wherein, The precast concrete base slab includes: The first reinforcing mesh (41) is embedded in the base plate (40); Multiple lattice beams (42) are arranged along the longitudinal length of the base plate (40), wherein the lower chord of each lattice beam is attached to the reinforcing mesh (41) and embedded in the base plate, and the upper chord protrudes from the upper surface of the base plate; A plurality of L-shaped pin / shear connectors (43), the plurality of L-shaped pin / shear connectors (43) having one end attached to the reinforcing mesh (41) and embedded within the base plate (40) and another end protruding from the longitudinal edge (40c) of the base plate; and Multiple void forming devices (1) according to any one of claims 1 to 14, the multiple void forming devices (1) being anchored to the reinforcing mesh 41 and embedded in the upper surface (40a) of the base plate (40).

16. The precast concrete base slab (4) according to claim 15, wherein, A plurality of void-forming devices (10) embedded and anchored to the upper surface (40a) of the base plate (40) are positioned on both sides of each lattice beam (42) along the longitudinal length of the base plate (40).

17. The precast concrete base slab (4) according to claim 15 or claim 16, wherein, The length and width along the upper surface (40a) of the base plate (40) include one or more post-tensioning tubes (44a, 44b) positioned longitudinally and laterally.

18. A concrete slab (5), comprising: The precast concrete base plate (4) according to any one of claims 15 to 17. The second reinforcing mesh (45) is situated on top of the concrete base plate (4) and attached to the upper chord of the plurality of lattice beams (42) that protrudes from the upper surface (40a) of the base plate (40); as well as A concrete top layer (51) is cast on the steel reinforcing mesh (45) and the precast concrete base plate (4).

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