GB2613049A

GB2613049A - Cavity former

Info

Publication number: GB2613049A
Application number: GB2211960.6A
Authority: GB
Inventors: Murray Roy
Original assignee: Rjm Services Ltd
Current assignee: Rjm Services Ltd
Priority date: 2022-08-16
Filing date: 2022-08-16
Publication date: 2023-05-24
Also published as: GB202211960D0

Abstract

A cavity former 10 for forming a rebar cavity in a concrete structure comprises a body 12 for creating the rebar cavity and an adapter 22. The body 12 has a first coupling part 14 and the adapter 22 has a second coupling part 24 for coupling to the first coupling part 14. The adapter 22 further has a threaded part 26 for coupling the cavity former 10 to a rebar coupler (32 figure 5). This can provide various configurations of cavity former 10 to be used with numerous combinations of rebars (30 figure 5) and rebar couplers (32 figure 32). A later embodiment relates to a method of constructing a concrete structure using said rebar cavity former.

Description

CAVITY FORMER

The present invention relates to a cavity former for forming a rebar cavity in a concrete structure and to a method of constructing a concrete structure using a cavity former.

Concrete structures are often reinforced with metallic reinforcing bars or "rebars" which are cast within the structure. In order to construct larger structures, it is advantageous to connect rebar sections end to end to create a longer rebar which can extend a greater distance through the structure. Adjacent rebar sections may be connected together with a rebar coupler having a pair of opposed threaded bores corresponding to threaded ends of the rebar sections.

/0 Larger concrete structures also tend to be constructed as plural sequentially cast concrete sections. When constructing concrete structures in this way, a free end of a first rebar section may be threaded into a first threaded bore of a rebar coupler. A cavity former may also be temporarily threaded into a second threaded bore of the rebar coupler. A first concrete section of the structure may then be /5 cast around a first rebar section, rebar coupler and cavity former. The cavity former thereby protects the second threaded bore from being filled with poured concrete during casting of the first concrete section. Once cast, the first concrete section may be cut to prepare its top surface for the next concrete section. In doing so, the cavity former may also be laterally cut. The cavity former is thereby revealed and can be removed from the second threaded bore to allow a second rebar section to be threaded into the second threaded bore of the rebar coupler. A second concrete section of the structure can then be cast around the second rebar section. If a further concrete section is required, the process of using a -2 -rebar coupler and cavity former can be repeated for each further rebar section and concrete section to be cast.

The existing arrangements have a number of disadvantages. For example, rebars and rebar couplers are available in a variety of different sizes. This means that numerous different cavity formers may be needed to suit various combinations of rebar and rebar coupler. Furthermore, it can sometimes be difficult to remove cavity formers from concrete structures once the concrete has been cast. It is therefore desired to provide improvements relating to cavity formers for forming rebar cavities in concrete structures.

/0 According to an aspect of the present invention there is provided a cavity former for forming a rebar cavity in a concrete structure, the cavity former comprising: a body for creating a rebar cavity, the body having a first coupling part; and an adapter having a second coupling part for coupling to the first coupling part, the adapter further having a threaded part for coupling the cavity former to a rebar coupler.

It will be appreciated that embodiments of the present invention can readily provide various configurations of cavity former that can be used with numerous combinations of rebars and rebar couplers. In particular, a body for the cavity former can be selected to suit the size of the rebar in question and an adapter for the cavity former can separately be selected that has a threaded part which fits the rebar coupler in question. The present invention may accordingly extend to a kit comprising plural (e.g. different) bodies and/or plural (e.g. different) adapters as described herein in any aspect or embodiment. Furthermore, the body (which may be laterally cut when cutting the concrete structure) may be discarded -3 -whereas the adapter (which may not be cut when cutting the concrete structure) may be re-used, thus reducing wastage and saving costs.

In preferred embodiments, the first coupling pad may be a first threaded part and the second coupling part may be a second threaded part. Thus, 5 according to another aspect of the present invention there is provided a cavity former for forming a rebar cavity in a concrete structure, the cavity former comprising: a body for creating a rebar cavity, the body having a first threaded part; and an adapter having a second threaded part for coupling to the first threaded part, the adapter further having a third threaded part for coupling the /0 cavity former to a rebar coupler.

In preferred embodiments, the (first, second and third) threaded parts may be configured such that, as the (e.g. body of the) cavity former is rotated to loosen the coupling between the cavity former and the rebar coupler, the coupling between the body and the adapter is tightened. Thus, despite the use of a threaded interface between the body and the adapter, the entirety of the cavity former may still easily be rotated to assist its removal from the concrete structure. In particular, rotation of the cavity former in a manner which tends to loosen the threaded connection between the cavity former and the rebar coupler, may also tend to tighten the threaded connection between the body and the adapter, thus allowing both the body and the adapter of the cavity former to be removed from the concrete structure upon rotation of the cavity former.

In preferred embodiments, the handedness of the (third) threaded part for coupling the cavity former to the rebar coupler may be opposite to the handedness of the first and second threaded parts. Most rebars have a right- -4 -handed or clockwise thread. Thus, the (third) threaded part for coupling the cavity former to the rebar coupler may have a right-handed or clockwise thread. Conversely, the first and second threaded parts may each have a left-handed or counter-clockwise thread. In some embodiments, the first threaded part may comprise a threaded bore and the second threaded part may comprise a threaded shaft. In other embodiments, the first threaded part may comprise a threaded shaft and the second threaded part may comprise a threaded bore. The third threaded part may comprise a threaded shaft for coupling the cavity former to a threaded bore of a rebar coupler.

/0 In less preferred embodiments, the first and second coupling parts may take other forms, such as each being a push-fit part. In these less preferred embodiments, the first and second coupling parts preferably do not rotate relative to one another once coupled together. Again, this will allow both the body and the adapter of the cavity former to be removed from the concrete structure upon rotation of the cavity former.

In embodiments, the (e.g. body of the) cavity former may have one or more engagement features, such as one or more voids, for rotationally coupling a removal tool to the cavity former. The removal tool may have one or more corresponding engagement features, such as one or more tines, for rotationally coupling the removal tool to the cavity former. When coupled to the one or more engagement features, rotation of the removal tool may cause rotation of the cavity former, which in turn may cause the cavity former to be threadingly removed from the rebar coupler. The one or more engagement features may comprise plural distinct engagement features. These embodiments can facilitate rotation and -5 -removal of the cavity former from the concrete section by providing a greater number of points of engagement for the removal tool.

In embodiments, the one or more engagement features may comprise one or more elongate voids that extend within the (e.g. body of the) cavity former. The 5 one or more elongate voids may each be elongate in a longitudinal direction with respect to the axis of rotation of the cavity former (i.e. during removal). The cavity former may also be elongate in the same direction as the elongate voids. The one or more elongate voids may comprise plural elongate voids which are substantially parallel to one another. These embodiments can allow the voids to /0 be exposed and useable when the cavity former has been laterally cut at various different heights. The one or more elongate voids may extend into the cavity former from a first end of the (e.g. body of the) cavity former, e.g. having the first coupling (e.g. threaded) part. The one or more elongate voids may be one or more blind elongate voids, e.g. which do not extend to a second end of the (e.g. body of the) cavity former which is opposite the first end of the (e.g. body of the) cavity former, e.g. having the first coupling (e.g. threaded) part. As a consequence of the one or more elongate voids being blind, concrete is prevented from entering those voids whilst casting the concrete structure, and thus concrete is prevented from rendering those engagement features unusable.

Furthermore, since the one or more blind elongate voids extend within the (e.g. body of the) cavity former, those one or more blind elongate voids will still be revealed, but only when the cavity former has been laterally cut together with the cast concrete section. -6 -

It is believed that the concept of using one or more blind elongate voids in this way is advantageous in its own right and not merely in combination with the other features, such as the adapter, as described herein. Thus, according to another aspect of the present invention there is provided a cavity former for forming a rebar cavity in a concrete structure, the cavity former comprising: a first end having a threaded part for coupling the cavity former to a rebar coupler; and one or more engagement features for coupling the cavity former to a removal tool, wherein the one or more engagement features comprises one or more blind elongate voids that extend into the cavity former from the first end.

/0 The cavity former of the above aspect may have one or more of the features as described herein in any aspect or embodiment as desired. For example, in preferred embodiments, the threaded part in the above aspect may indirectly couple the cavity former to a rebar coupler via an adapter as described herein in any aspect or embodiment (i.e. the threaded part in the above aspect may be the "first threaded part" as described herein). Alternatively, in less preferred embodiments, the threaded part in the above aspect may directly couple the cavity former to a rebar coupler (i.e. the adapter as described herein may not be used).

In any of the aspects or embodiments described herein, the (e.g. body and/or adapter of the) cavity former may be tapered. The cavity former may taper from a wider span (e.g. diameter) away from the threaded part for coupling the cavity former to a rebar coupler to a narrower span (e.g. diameter) closer to the threaded part for coupling the cavity former to a rebar coupler. The (e.g. body and/or adapter of the) cavity former may have a shape which is substantially -7 -conical and/or substantially a frustum, e.g. frustoconical. The (e.g. body and/or adapter of the) cavity former may be substantially circular in cross-section. These embodiments can facilitate rotation and removal of the cavity former from the concrete structure.

In embodiments, the (e.g. body and/or adapter of the) cavity former may have a span (e.g. diameter) in the range 12mm-100mm. The (e.g. body of the) cavity former may have a greatest span (e.g. diameter) in the range 25mm100mm. The (e.g. adapter of the) cavity former may have a smallest span (e.g. diameter) in the range 12mm-75mm. At the interface between the body and the adapter when coupled together, the span (e.g. diameter) of the body may be substantially the same as the span (e.g. diameter) of the adapter. These embodiments can facilitate rotation and removal of the cavity former from the cast concrete structure by providing a smooth transition between the body and the adapter when coupled together. The cavity former (e.g. the body and the adapter together) may have a length in the range 50mm-300mm (excluding any threaded parts). The length of the body may be longer than the length of the adapter. The adapter may have a length in the range 10mm-50mm (excluding any coupling parts). The body may have a length in the range 25mm-275mm (excluding any coupling parts). These embodiments can provide a relatively longer body which can more easily be cut to reveal one or more elongate voids therein.

In embodiments, the cavity former may be formed of a plastics material, such as High Density Poly Ethylene (HDPE), nylon or polypropylene. Alternatively, the cavity former may be formed of a metallic material. These embodiments can provide a cavity former which is robust during casting and -8 -readily recyclable once cut in use. The (e.g. body of the) cavity former may be single-use since it is cut in use. The adapter may be single use, or may be reusable since it is not cut in use.

According to another aspect of the present invention, there is provided a 5 method of constructing a concrete structure, the method comprising: coupling an end of a first rebar section to a first threaded bore of a rebar coupler; coupling a cavity former as described herein in any aspect or embodiment to a second threaded bore of the rebar coupler; casting a first concrete section around the first rebar section, rebar coupler and cavity former; optionally cutting through the /0 first concrete section and cavity former; rotating and removing the cavity former to create a cavity in the concrete section leading to the second threaded bore of the rebar coupler; coupling an end of a second rebar section to the second threaded bore of the rebar coupler; and casting a second concrete section around the second rebar section.

In embodiments, the method may further comprise coupling a body of the cavity former to an adapter of the cavity former. Coupling the cavity former to the second threaded bore of the rebar coupler may comprise coupling the adapter of the cavity former to the second threaded bore of the rebar coupler. Coupling the adapter of the cavity former to the second threaded bore of the rebar coupler may be performed before or after coupling the body to the adapter. Cutting through the first concrete section and cavity former may reveal one or more engagement features (e.g. one or more elongate voids) for rotationally coupling the cavity former to a removal tool. Removing the cavity former may comprise simultaneously removing the body and adapter by rotating the cavity former, e.g. -9 -using a removal tool. The body may be directly rotated, e.g. using a removal tool, whereas the adapter may be indirectly rotated upon rotation of the body. The body (which may be laterally cut when cutting the first concrete section) may be discarded whereas the adapter (which may not be cut when cutting the first concrete section) may be re-used, thus reducing wastage and saving costs.

In embodiments, if further concrete sections are desired, the other end of the second rebar section may be coupled to a first threaded bore of a second rebar coupler. A second cavity former as described herein in any aspect or embodiment may be coupled to a second threaded bore of the second rebar /0 coupler. The second concrete section may then be cast around the second rebar section, second rebar coupler and second cavity former. Optionally, the second concrete section and second cavity former may then be cut. The second cavity former may then be rotated and removed to create a cavity leading to the second threaded bore of the second rebar coupler. An end of a third rebar section may then be coupled to the second threaded bore of the second rebar coupler. A third concrete section may then be cast around the third rebar section. The process of using a rebar coupler and cavity former as described herein in any aspect or embodiment may be repeated for each further rebar section and concrete section to be cast.

By way of example only, embodiments of the invention will now be described in detail with reference being made to the accompanying drawings in which: -10 -Figure 1 is a perspective view of a cavity former according to an embodiment of the present invention, with a body and an adapter of the cavity former being shown uncoupled from one another; Figure 2 is a top view of the body of the cavity former of Figure 1 with internal/obscured features being shown with dashed lines; Figure 3 is a side view of the body of the cavity former of Figure 1 with internal features being shown with dashed lines; Figure 4 is a side view of the adapter of the cavity former of Figure 1; and Figures 5-8 illustrate a method of constructing a concrete structure using the cavity former of Figure 1.

Figures 1-4 illustrate a cavity former 10 according to an embodiment of the present invention. In this embodiment, the cavity former 10 is formed of High Density Poly Ethylene (HDPE), although other less preferred materials could be used. The cavity former 10 comprises a body 12 having a first threaded part 14 at a lower end 16 of that body 12. In this embodiment, the first threaded part 14 is a threaded bore having a left-handed or anticlockwise thread. The body 12 also has engagement features 18 in the form of a pair of elongate blind voids. The engagement features 18 extend within the body 12 from the lower end 16, but do not extend all the way to an upper end 20 of the body 12. As a consequence, concrete is prevented from entering the engagement features 18 from above during casting of a concrete structure. The engagement features 18 can be rotationally coupled to the tines of a removal tool (not shown), but only once the cavity former 10 has been laterally cut to reveal those engagement features 18 (see Figure 6). The cavity former 10 also comprises an adapter 22 having a -11 - second threaded part 24 in the form of a threaded shaft. The second threaded part 24 can be coupled to the first threaded part 14 so as to assemble the cavity former 10. This will also close off the openings to the engagement features 18 at the lower end 16 of the body 12. The second threaded part 24 again has a left-handed or anticlockwise thread that corresponds to the first threaded part 14. The adapter 22 also has a third threaded part 26 in the form of a threaded shaft for coupling the cavity former 10 to a threaded bore of a rebar coupler (see rebar coupler 32 in Figures 5-8). In contrast to the first and second threaded parts, the third threaded part 26 has a conventional right-handed or clockwise thread corresponding to a typical rebar coupler. The body 12 and adapter 22 are interchangeable to suit a specific combination of rebar and rebar coupler to be used when casting a particular concrete structure. As is shown, the body 12 and adapter 22 are both frustoconical in shape and are linearly tapered to facilitate rotation and removal of the cavity former 10 from a cast concrete structure. In this embodiment, the cavity former 10 has a greatest diameter of around 65mm at the upper end 20 of the body 12 and a smallest diameter of around 50mm at the lower end of the adapter 22. The cavity former 10, when assembled, has an overall length of around 175mm (excluding the third threaded part 26).

Figures 5-8 illustrate a method of constructing a concrete structure 44 using the cavity former 10. As is shown in Figure 5, an end of a first rebar section is threadingly coupled to a first threaded bore 31 of a rebar coupler 32. The cavity former 10 as described above is coupled to a second threaded bore 33 of the rebar coupler 32. A first concrete section 34 is then cast around the first rebar section 30, rebar coupler 32 and cavity former 10. As is shown in Figure 6, a horizontal saw cut is then made through the first concrete section 34 and cavity former 10 to expose the engagement features 18. As is illustrated in Figure 7, the cavity former 10 is then rotated and removed using a tined removal tool (not shown) to create a cavity 38 in the first concrete section 34 leading to the second threaded bore 33 of the rebar coupler 32. As indicated above, the threaded parts of the cavity former 10 are configured such that, as the body 12 of the cavity former 10 is rotated to loosen the coupling between the adapter 22 and the rebar coupler 32, the coupling between the body 12 and the adapter 22 will be tightened. This helps to ensure that both the body 12 and the adapter 22 are /o removed. The exposed surface 36 of the first concrete section 34 may also be abraded to improve adhesion with the next concrete section to be cast. As is shown in Figure 8, an end of a second rebar section 40 is coupled to the second threaded bore 33 of the rebar coupler 32. A second concrete section 42 is then cast around the second rebar section 40. Further concrete sections can be cast sequentially on top of the second concrete section 42 in a similar manner as desired.

Claims

-13 -CLAIMS1. A cavity former for forming a rebar cavity in a concrete structure, the cavity former comprising: a body for creating a rebar cavity, the body having a first coupling part; and an adapter having a second coupling part for coupling to the first coupling part, the adapter further having a threaded part for coupling the cavity former to a rebar coupler.
2. A cavity former as claimed in claim 1, wherein the first coupling part is a first threaded part and the second coupling part is a second threaded part.
3. A cavity former as claimed in claim 2, wherein the threaded parts are configured such that, as the cavity former is rotated to loosen the coupling between the cavity former and the rebar coupler, the coupling between the body and the adapter is tightened.
4. A cavity former as claimed in claim 2 or 3, wherein the handedness of the threaded part for coupling the cavity former to the rebar coupler is opposite to the 15 handedness of the first and second threaded parts.
5. A cavity former as claimed in any one of claims 2-4, wherein the threaded part for coupling the cavity former to the rebar coupler has a right-handed or clockwise thread.
6. A cavity former as claimed in any one of claims 2-5, wherein the first and second threaded parts each have a left-handed or counter-clockwise thread.
7. A cavity former as claimed in any one of claims 2-6, wherein the first threaded part comprises a threaded bore and the second threaded part comprises a threaded shaft. 8.
A cavity former as claimed in any one of the preceding claims, wherein the cavity former has one or more engagement features for rotationally coupling a removal tool to the cavity former.
9. A cavity former as claimed in claim 8, wherein the one or more engagement features comprises plural distinct engagement features.
10. A cavity former as claimed in claim 8 or 9, wherein the one or more engagement features are one or more elongate voids that extend within the cavity former.
11. A cavity former as claimed in claim 10, wherein the one or more elongate voids are each elongate in a longitudinal direction with respect to the axis of rotation of the cavity former.
12. A cavity former as claimed in claim 10 or 11, wherein the one or more elongate voids comprises plural elongate voids which extend substantially parallel to one another.
13. A cavity former as claimed in claim 10, 11 or 12, wherein the one or more elongate voids extend into the cavity former from a first end of the cavity former having the first coupling part.
14. A cavity former as claimed in any one of claims 10-13, wherein the one or more elongate voids are one or more blind elongate voids.
15. A cavity former as claimed in any one of claims 10-14, wherein the one or more elongate voids do not extend to a second end of the cavity former which is opposite a first end of the cavity former having the first coupling part.
16. A cavity former as claimed in any one of the preceding claims, wherein the cavity former is tapered.
17. A cavity former as claimed in any one of the preceding claims, wherein the cavity former tapers from a wider span away from the threaded part for coupling the cavity former to the rebar coupler to a narrower span closer to the threaded part for coupling the cavity former to the rebar coupler.
18. A cavity former as claimed in any one of the preceding claims, wherein the cavity former has a shape which is substantially conical and/or substantially a frustum.
19 A cavity former as claimed in any one of the preceding claims, wherein the cavity former is substantially circular in cross-section.
20. A method of constructing a concrete structure, the method comprising: coupling an end of a first rebar section to a first threaded bore of a rebar coupler; coupling a cavity former as claimed in any one of the preceding claims to a second threaded bore of the rebar coupler; casting a first concrete section around the first rebar section, rebar coupler and cavity former; rotating and removing the cavity former to create a cavity in the concrete section leading to the second threaded bore of the rebar coupler; coupling an end of a second rebar section to the second threaded bore of the rebar coupler; and casting a second concrete section around the second rebar section.