GB2356888A

GB2356888A - Former element

Info

Publication number: GB2356888A
Application number: GB9927639A
Authority: GB
Inventors: Alastair Nigel Thompson
Original assignee: ANTHIRE Ltd
Current assignee: ANTHIRE Ltd
Priority date: 1999-11-24
Filing date: 1999-11-24
Publication date: 2001-06-06
Anticipated expiration: 2019-11-24
Also published as: GB2356888A8; GB2356888B; GB9927639D0

Abstract

The former element, for forming foot- and/or hand-recesses in a cast-in-situ concrete structure formed by casting concrete around a main former, comprises a hollow casing 1 with an open face 3 which is designed to be releasably secured to the main former so as to prevent the ingress of concrete into the casing during casting. The element is preferably box shaped or may have a curved face so as to match the curve of a main former and has a flange 7 around its open face to allow the element to be secured to the main former using nails, bolts etc. The element may also include an internal surface 9 formed as a grip or tread, retaining grooves 21,23 for receiving a fixing tool 37 to secure the element in place during casting and a coloured strip 32 which extends from the element so as to extend along the external surface of the concrete once it's cast so as to provide a visual aid. The element is designed to remain embedded in the concrete once the main former is removed.

Description

2356888 FORMERELEMENT The present invention relates to former elements for

use in concrete channels formed at the base of manholes.

Concrete channels are formed at the base of manholes to carry the flow of liquids ftorn one or more inlet pipes to one or more outlet pipes.

Co-pending patent applications GB2300663 and PCT/GB98/02719 describe methods for forming concrete channels between two or more pipe ends in a manhole base.

The applications provide for a shuttering assembly which can be easily installed and then easily removed once concrete has been introduced and allowed to set to a predetermined degree.

Conventionally, polystyrene blocks are used with such shuttering assemblies to create foot or toe holds and provide rebates for safety chain fixings. Polystyrene blocks are attached to an external portion of the assembled shuttering before concrete is cast around the system and allowed to set to a predetermined degree.

After removing the shuttering assembly the polystyrene block is typically removed by tearing or breaking it out, thus defining a foot- or hand-recess in the side of the concrete channel. Alternatively, the polystyrene may be removed by means of chemical dissolution. The problem with this method arises in the frequent displacement of the polystyrene block due to the tremendous weight of concrete which is applied around the assembled system. Furthermore, the process of chemical dissolution releases noxious chemicals which is disadvantageous both from an environmental and social point of view. There is also the associated safety problem of releasing explosive organic vapours into a confined space.

According to a first aspect of the present invention, there is provided a foriner element for use in forming foot- or hand-recesses in a cast-in-situ concrete structure formed by casting concrete around a main former, the former element comprising a hollow casing having a face provided with an opening therein, wherein the face is releasably attachable to an external portion of the main former in such a way as to prevent ingress of unset concrete into the casing during casting.

According to a second aspect of the present invention, there is provided a method of forming hand- or foot-recesses in a cast-in-situ concrete structure cast around a main former, comprising the steps of:

i) releasably attaching a hollow casing having a face provided with an opening therein to an external surface of the main former in such a way that the face abuts the external surface so as to prevent ingress of concrete into the casing during casting; ii) casting concrete around the main former and the hollow casing and allowing the concrete to set to a predetermined degree; iii) detaching the hollow casing from the main former and then removing the main former, leaving the hollow casing embedded in the concrete with the opening exposed, thus defining a footor hand-recess.

For the avoidance of doubt, the expression 'main former' is used herein to denote shuttering assemblies and any other type of formwork.

The hollow casing may take any suitable shape, but is typically in the form of a flat- sided box made of wood, metal, plastics or any other suitable material. The important feature is that the hollow casing has a face with an opening which serves to define the opening of a foot- or hand-recess, the rest of the casing serving to define the main body of the recess. This is because the hollow casing remains embedded in the concrete after casting. Although the opening may be defined by the whole area of one side of the box, it should be understood that this is by no means an essential 2 feature and the aperture may simply be of sufficient size to place a hand or foot therein.

The face having the opening therein may be substantially flat, and therefore suitable for attachment to, for example, a planar shuttering element of the main former, or may be curved or otherwise shaped so as to fit snugly against a curved or irregular surface and to prevent ingress of fluid concrete between the face and the surface and thus into the hollow casing. Advantageously, the face having the opening therein is provided with a flange around its perimeter so as to allow the hollow casing to be at least temporarily attached to the main former by way of nails or bolts or other attachment means. In preferred embodiments, the flange is provided with a resilient or elastomeric sealing element which helps to ensure a snug fit against the main former.

Advantageously, the hollow casing is provided with keying means for providing a secure fit into the concrete once this has set. The keying means may comprise a flange around or other protrusion from a part of the hollow casing remote from the face having the opening therein.

As mentioned above, the hollow casing may be attached to an exterior surface of the main former by way of nuts or bolts. However, these means of attachment may not be sufficient to keep the hollow casing secured to the main former in view of the substantial impact of the concrete when this is being cast. Accordingly, the hollow casing may be provided with additional attachment means for releasably affixing it to the main former. This additional attachment means may take the form of a fixing tool adapted to be releasably retained at one end thereof within the hollow casing, its other end projecting through a hole or slot provided in the main former and secured thereto by way of suitable retaining means. A specific example of such a fixing tool has a cross-bar portion adapted to be releasably retained by two retaining holes or grooves provided in a pair of generally opposed internal faces of the hollow casing, and a tongue portion projecting generally orthogonally from the cross-bar portion and 3 provided with at least one longitudinal slot therein. The retaining grooves or holes preferably do not project all the way through the hollow casing, and may be provided with reinforcement means which may project from the outside of the hollow casing.

Where the hollow casing is box-shaped, a retaining groove or hole may be provided, generally centrally located, in each of the four side walls, thus allowing the fixing tool to be attached in two alternative generally orthogonal positions. In use, the cross-bar portion of the tool is inserted into the hollow casing through the opening therein and located within the retaining grooves or holes. The hollow casing is then brought up to the main former and the tongue portion of the fixing tool fed through a joint in the main former or a slot provided therein for that purpose. The tongue portion is then pulled from the internal side of the main former so as to bring the face of the hollow casing which has the opening therein snugly up against the external surface of the main former. A wedge is then placed with its narrow end first into the longitudinal slot of the tongue portion so as to brace the tongue portion (and hence the fixing tool and the hollow casing) firmly against the main former.

An interior surface of the hollow casing may be provided with a structure defining a tread or grip.

Embodiments of the present invention may also provide for marker strips to be located on or in the surface of the concrete so as to indicate the position of the resulting hand- or foot-recess in the finished concrete structure. At least one exterior surface of the hollow casing adjacent to the face having the opening therein may be provided with a spring member which has an end which extends slightly beyond the face in a direction away from the opening. In this way, when the face is brought up snugly to the exterior of the main former, the end of the spring member will press tightly against this surface.

A marker strip, which may be formed of a plastics material and which is preferably brightly coloured, is attached to the end of the spring member and is held tightly thereby against the exterior of the main former in such a way that when concrete is 4 cast and the main former is removed, the marker strip is visibly embedded in the surface of the resultant concrete structure. This is particularly useful when a vertical series of hand- or foot-recesses is being formed, since the marker strips can be positioned so as to link vertically adjacent recesses and thereby to provide an indication to a person using the recesses to climb or descend the surface of the concrete structure as to where to feel for the next hand- or foot-hold.

The marker strip attached to that former element located nearest the surface of the concrete is taken to the top of the cast face and turned over onto the top of the concrete casting which is typically a slightly sloping horizontal surface. This section of the strip is provided with an anti-slip surface for safety reasons.

The present invention will now be described by way of example only and with reference to the accompanying drawings wherein:

Figure I is a perspective view of a former element according to the present invention.

Figure 2 is a side elevation of a former element according to the present invention and main former wherein the face of the former element is releasably attached to and abuts an external surface of the main former which is a piece of shuttering.

Figure 3 is a side elevation of a former element according to the present invention wherein the face of the former element is releasably attached to and abuts an external surface of the main former which is a piece of timber framework.

Figure 4 is a side elevation of a former element according to the present invention showing the position of a marker strip which has been taken to the top of the cast face, turned over onto the top of the concrete casting and embedded in the concrete surface.

Figure 5 shows a section of the marker strip in more detail illustrating mush-room shaped nodules on the rear face of the strip which are embedded in the concrete.

As shown in Figure 1 a former element of the present invention comprises a hollow, flat sided, plastic casing 1 which is box shaped and approximately 15 cm x 15 cm x cm. One side of the box, hereinafter referred to as face 3, is provided with a square-shaped opening which defines mouth portion 5, thus allowing access into the interior of the box.

A projecting flat lip or flange element 7 surrounds the square-shaped opening or mouth portion 5 and includes a series of holes 6, one placed at each corner thereof Located upon flange element 7 is elastomeric, resilient seal 8. Rear face 4 of hollow casing 1 is also provided with a flange element or keying means 10. In the embodiment of figure 1, each flange element 7 and 10 projects outwardly from the front and rear faces 3 and 4 by approximately 30 mm and 5 mm respectively.

The bottom wall 9 of hollow casing 1 is provided with a tread which comprises a series of ribs 11 positioned at equidistant intervals therealong. Retaining grooves 13 and 23, comprising an elongated hole, protrude partially through the surface of walls 9 and 17 respectively and are centrally positioned between opposing side walls 15, 17, 9 and 19 respectively, located towards the mouth portion 5.

Retaining grooves 21 and 25 each comprise an elongated slot which is located internally of the hollow casing within side walls 15 and top wall 19 respectively and which protrude only partially through the respective surface. Each groove or slot extends from a substantially central position within each wall towards the face 3 of the hollow casing 1, stopping short of mouth portion 5 at a distance which corresponds to that at which elongated hole or retaining groove 13 and 23 are located behind the mouth portion 5.

6 External surfaces of side wall 17 and top wall 19 are reinforced at positions 27 and 29 which correspond to the position of internal retaining grooves 23 and 25.

Although not shown in Figure 1, side wall 15 and bottom wall 9 are provided with similar reinforcement which corresponds to the position of the internal retaining grooves 21 and 13.

External surface of top wall 19 is provided with a spring member 3 1. The end 3 2 of spring member 31 extends slightly beyond the face of hollow casing I in a direction away from opening 5 and is attached to a fluorescent, 50 mm wide (Nigel, is mm correct ?) marker strip 33.

In one embodiment of the invention, attachment of the former element to the main former is achieved by way of nails or bolts which are accommodated within the holes 6 provided in each comer section of the front flange element 7. Figure 3 illustrates this method of attachment wherein nails 12 are used to secure front flange element 7 of hollow casing I to timber framework 44.

When in use, open face 3 of hollow casing I is positioned on the external portion of the main former at the desired position and releasably attached thereto using suitable attaching means. In view of the substantial impact of the concrete when it is being cast, a preferred embodiment of the invention involves the use of fixing tool 37 in the attachment of the former element to the main former.

As exemplified in Figure 1, fix ing tool 37 is a metallic, T-shaped implement and comprises a cross-bar or metallic rod 39 which is of sufficient length to span between any elongated hole and opposite slot and have sufficient bearing in such apertures to hold the former firmly in place. The handle portion of fixing tool 37 comprises a flat projection or tongue portion 45 which extends orthogonally from the centre of metallic rod 39 and is provided with two longitudinal slots 40.

7 Fixing tool 37 is introduced at an angle into hollow casing I and each end of rod 39 allowed to mate with retaining grooves 21 and 23 in side walls 15 and 17 respectively. Each end of rod 39 is then releasably retained within the respective groove. As shown in Figure 2, hollow casing I is bought up to the main former which comprises shuttering 46 and tongue portion 45 of fixing tool 37 is fed through slot orjoint 47. Tongue portion 45 is pulled from the internal side of shuttering 46 so that face 3 of hollow casing I is flush with the external surface of shuttering 46. A wedge 49 is then fed, narrow end leading, into a longitudinal slot 40 of tongue portion 45. As shown in Figure 1, tongue portion 45 is provided with two longitudinal slots 40. Accordingly a fixing tool 37 is adaptable for use with a range of different main former thicknesses and a specific longitudinal slot 40 can be chosen in order to brace tongue portion 45 (hence fixing tool 37 and hollow casing 1) firmly against the main former of use.

Flange element 7 is also provided with elastomeric, resilient seal 8 which further ensures a snug fit of the former element against the main former 44, 46. Resilient seal 8 also helps to accommodate any curvature in the surface of the framework to which the former element is attached.

With face 3 of hollow casing I snug against the exterior of the main former, end 32 of spring member 31 presses tightly against this surface; as shown in Figure 2.

Fluorescent, 50 mm wide flexible marker strip 33 is therefore held tightly against the exterior of the main former. As shown in Figure 3, a small nail 50 holds the flexible marker strip 33 against the timber framework to which the hollow casing I is attached.

Concrete is then cast around the main former and hollow casing I and allowed to set to a predetermined degree. Since face 3 of hollow casing I abuts the external surface of the main former, any ingress of concrete into the casing is prevented.

8 Hollow casing 1 is then detached from the main former which is removed. Hollow casing 1 remains embedded in the concrete with opening 5 exposed, thus defining a foot- or hand recess. Flange element or keying means 10 provided in rear face 4 of hollow casing 1 provides a secure fit into the set concrete.

When main former 46 is removed, flexible marker strip 33 is visibly embedded in the surface of the resultant concrete structure and provides a useful indication to the user as to the position of the recess. When a vertical series of hand or foot recesses is formed by locating a series of formers 1 against the external surface of a main former, marker strips 33 are positioned so as to link vertically adjacent recesses and provide an indication to a person using the recesses to climb or descend the surface of the concrete structure as to where to feel for the next hand- or foothold.

As shown in Figure 4, the marker strip 33 attached to that former element located nearest the surface of the concrete is taken to the top of the cast face and turned over onto the top of the concrete casting which is a slightly sloping horizontal surface.

This section of the strip 34 which is embedded in the concrete is provided with an anti-slip surface for safety reasons. Ribs 11 positioned along bottom wall 9 define a tread or grip and provide extra traction for the person using the recess.

Figure 5 shows the marker strip in more detail illustrating mushroom shaped nodules 49 which are located on the rear face of the strip. Mushroom shaped nodules 49 are embedded in the concrete and serve to secure the marker strip to the exterior of the main former.

9

Claims

1. A former element for use in forming foot- or hand-recesses in a castin-situ concrete structure formed by casting concrete around a main former, the former element comprising a hollow casing having a face provided with an opening therein, wherein the face is releasably attachable to an external portion of the main former in such a way as to prevent ingress of unset concrete into the casing during casting.

2. A former element as claimed in claim 1 wherein the hollow casing is made of wood, metal or plastics.

3. A former element as claimed in claim 1 or claim 2 wherein the hollow casing is box-shaped.

4. A former element as claimed in any one of the preceding claims wherein the face having an opening therein is flat.

5. A former element as claimed in any one of claims 1 to 3 wherein the face having an opening therein is curved or otherwise shaped so as to fit snugly against a curved or irregular surface and to prevent ingress of fluid concrete between the face and the surface and thus into the hollow casing.

6. A former element as claimed in any one of the preceding claims wherein the face is provided with a flange around its perimeter.

7. A former element as claimed in claim 6 wherein the flange is provided with holes to accommodate suitable securing means for attachment of the former element to the main former.

8. A former element as claimed in claim 7 wherein the securing means are nails or bolts.

9. A former element as claimed in any one of the preceding claims wherein the face is provided with a resilient or elastomeric sealing element which helps to ensure a snug fit against the main former.

10. A former element as claimed in any one of claims 6 to 8 or claim 9 depending from any one of claims 6 to 8 wherein the flange is provided with a resilient or elastomeric sealing element which helps to ensure a snug fit against the main former.

11. A former element as claimed in any one of the preceding claims wherein part of the hollow casing is provided with keying means for providing a secure fit into the concrete once the concrete has set.

12. A former element as claimed in claim 11 wherein the keying means comprises a flange from a part of the hollow casing spaced from the face having an opening therein.

13. A former element as claimed in any one of the preceding claims wherein an internal surface of the hollow casing is provided with a structure which defines a tread or a grip.

14. A former element as claimed in claim 13 wherein said grip comprises a series of ribs positioned at intervals along the internal surface.

15. A former element as claimed in claim 14 wherein said ribs are positioned at equidistant intervals along the internal surface.

16. A former element as claimed in any one of the preceding claims wherein said hollow casing is provided with additional attachment means for releasably attaching it to the main former, the additional attachment means including two retaining holes or grooves in a pair of generally opposed internal faces of the hollow casing, the retaining holes or grooves being adapted to receive a fixing tool.

17. A former element as claimed in claim 16 wherein the retaining grooves do not project all the way through the hollow casing and are provided with reinforcement means which project externally from outside of the hollow casing.

18. A former element as claimed in any one of claims 16 or 17 wherein the retaining grooves are centrally located in at least one pair of side walls.

19. A former element as claimed in any one of claims 16 or 17 wherein the retaining grooves are centrally located in two pairs of side walls.

20. A former element as claimed in any one of claims 16 to 19 wherein said attachment means further includes a fixing tool which is adapted to be releasably retained at one end thereof within the retaining grooves in the hollow casing, its other end projecting through a hole or slot provided in the main former and secured thereto by way of suitable retaining means.

21. A former element as claimed in claim 20 wherein said fixing tool comprises a cross-bar portion adapted to be releasably retained by two retaining grooves provided in a pair of generally opposed internal faces of the hollow casing, and a tongue portion projecting generally orthogonally from the cross-bar portion which, in use, is fed through a slot provided in the main former and provided with at least one longitudinal slot therein for location of wedge shaped securing means.

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22. A former element as claimed in any one of the preceding claims wherein at least one exterior surface of the hollow easing adjacent to the face having an opening therein is provided with a spring member which has an end extending beyond the face in a direction away from the opening and a marker strip attached thereto so that when concrete is cast and the main former is removed, the marker strip is visibly embedded in the surface of the resultant concrete structure.

23. A former element as claimed in claim 22 wherein said marker strip is formed of plastics material and is brightly coloured.

24. A method of forming hand- or foot-recesses in a cast-in-situ concrete structure cast around a main former, comprising the steps of.

25. A method according to claim 24 further comprising a hollow casing as claimed in claim 20 or 21 wherein said method includes the steps of:

i) inserting the cross bar portion of the fixing tool into the hollow casing through the opening therein and locating it within the retaining grooves; 13 ii) bringing the hollow casing up to the main former and feeding the tongue portion of the fixing tool through a slot provided therein; iii) pulling the tongue portion from the internal side of the main former so as to bring the face of the hollow casing which has the opening therein snugly up against the external surface of the main former; iv) placing a wedge with its narrow end first into the longitudinal slot of the tongue portion so as to brace the tongue portion (and hence the fixing tool and the hollow casing) firmly against the main former.

26. A method according to any one of claims 24 or 25 further comprising a hollow casing as claimed in any of claims 22 or 23 wherein said method includes the step of bringing the face of the hollow casing up to the exterior of the main former and allowing the end of the spring member, and therefore the marker strip, to press tightly against this surface so that when the concrete is cast and the main former removed, the marker strip is visibly embedded in the surface of the resultant concrete structure.

27. A method according to claim 26 wherein the marker strip is taken to the top of the cast face and turned over onto the top of the concrete casting.

28. A method according to claim 27 wherein the section of the marker strip which is turned over onto the top of the concrete casting is provided with an anti- slip surface.

29. A former element substantially as hereinbefore described with reference to the accompanying drawings.

30. A method of forming hand- or foot- recesses in a cast-in-situ concrete structure substantially as hereinbefore described with reference to the accompanying drawings.

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