AU582910B2

AU582910B2 - Reinforcing cage with spring-biassed stirrups

Info

Publication number: AU582910B2
Application number: AU64012/86A
Authority: AU
Inventors: Kaj Adler
Original assignee: Internationella Siporex AB
Current assignee: Internationella Siporex AB
Priority date: 1985-09-27
Filing date: 1986-09-23
Publication date: 1989-04-13
Anticipated expiration: 2006-09-23
Also published as: DE3683376D1; SE8504482D0; SE453680B; AU6401286A; NO872154L; KR880700135A; DK266587A; WO1987002087A1; EP0325578B1; EP0325578A1; NO872154D0; DK266587D0; JPS63502293A; SE8504482L

Description

A REINFORCING CAGE FOR USE IN MOULDS WHEN CASTING ARTIFICIAL STONE MATERIAL, AND A METHOD FOR MANUFACTURING THE REINFORCING CAGE

The present invention relates to a reinforcing cage intended for use when casting artificial materials. By "artificial stone materials" is meant primarily light-weight concrete, particularly light-weight aerated concrete, although the term as used here shall also be understood to include conventional concrete, i.e. so-called heavy-weight aggregate concrete.

More specifically, the invention relates to a reinforcing cage intended for the aforesaid purpose which comprises a first group of elongated, mutually parallel reinforcing irons or rounds intended to reinforce the upper edge or side surface of a slab or plate cast from the artificial stone material, and a second group of elongate, mutually parallel reinforcing irons or rounds intended to reinforce the bottom edge or side surface of the same slab or plate, the two groups of reinforcing irons being connected together by transverse stirrup-like devices. Such slabs or plates are primarily used in the construction of ceiling structures and joists, beams, etc., in various types of building constructions.

A reinforcing cage of this kind is known in connection with the reinforcement of gas concrete structures, the cage being placed in the mould in its open form. The cage is suspended in the mould and held positioned therein with the aid of separate positioning and securing rods which, through the intermediary of auxiliary support elements which rest on the upper edges of the mould or form, secure and support the reinforcing cage in one given rotational position of the rods prior to and during the moulding operation, but which in another position of rotation of said rods occopy a position in which they can be released from engagement with the support elements when the aerated concrete structure has set sufficiently to enable it to support the reinforcing cage unaided. As soon as the concrete structure has reached this state of solidification, the positioning and securing rods are withdrawn from said structure, and the structure, in the majority of cases, is then divided into smaller elements, which are preferably cured in an autoclave.

The known reinforcing cages of this kind are normally of U- shaped, or substantially U-shaped cross-section. In the case of one such known cage, the U-shaped cross-sectional configuration is obtained by connecting, preferably by welding, one group of said reinforcing irons or rounds intended to form a reinforcement for the bottom edge or side surfaces of the moulded structure to the central part of those cross pins which, subsequent to being bent, form the aforesaid transverse stirrup-like devices, and by attaching the reinforcing irons or rounds in the other of said groups in uniform spaced relationship to respective end positions of the cross pins, said end portions, subsequent to being bent, forming inwardly directed end parts which extend parallel with the central part of respective pins, these latter end parts being connected to the centre-pieces corresponding to the central part of the cross pins by means of a side piece associated with each end part and in each particular case corresponding to the legs of the U-shape. Thus, the resultant reinforcing cage has a rectangular profile, of which the one of the long sides of the rectangle is broken, and is subsequently provided with means for guiding a positioning and securing rod in one of the cage side-pieces, and means in the other of the cage side-pieces for guiding and loosely carrying the cage in a mould or form so as to be embedded in a solidifiable light-weight aerated concrete mass, whereupon the cage is turned through 90° and one or more positioning end suspension rods are placed in position. The cage incorporating said rods is then introduced into the form or mould and the concrete allowed to set. As soon as the moulded concrete structure has set sufficiently to support the weight of the reinforcing cage unaided, the rods are detached from the cage and withdrawn from the solidifying structure, which is then optionally cut into smaller elements and treated with steam under pressure in order to steam cure the structure or structures. One drawback with such reinforcing cages is that they present an interrupted configuration when seen in cross-section, therewith impairing the mechanical strength of the resultant moulded structure. A further drawback is that two working operations are required in the manufacture of the cage, in bringing the cage positioning and securing rods and the cage positioning and carrying rods in position in the form or mould prior to pouring the porous concrete forming material thereinto.

In a further embodiment of reinforcing cages of U-shaped cross-section, the reinforcing rods or rounds of the group intended to reinforce the bottom edge or side surface of the moulded structure are attached to a central part of respective cross pins which, subsequent to being bent, are intended to form the transverse stirrup-like connectors in the cage, and the reinforcing irons or rounds intended to form the top edge or side surface reinforcement in said structure are uniformly distributed on two side parts of the cross pins which are intended, subsequent to being bent, to form the side-pieces of the transverse connectors, whereafter the resultant mat of reinforcing rods and cross pins is bent to the intended U-shape, and the thus constructed reinforcing cage is provided with means for guiding, or suspending and guiding, the positioning rods in the side-pieces of the cage and, after being turned through 90 , is inserted in and suspended in the mould by means of the securing and positioning rods . As with the aforedescribed cage, the reinforcing cage of this construction also presents an interruption when seen in cross-section, and two different working operations are required in order to bring the aforesaid means into their respective operative positions.

The object of the invention is to eliminate these drawbacks fully or at least substantially.

To this end it is proposed in accordance with the invention that in a reinforcing cage or like device of the aforesaid kind the legs of the transverse stirrups are held in a sprung or spring biassed position by means of hooked cross- connectors or the like.

According to one preferred embodiment of the invention the legs of the transverse stirrups are such as to be urged away from one another in their sprung state by an inherent spring force.

According to another embodiment of the invention each of the hooked cross-connectors comprises a reinforcing iron or round which is hooked at one end thereof. The advantage afforded hereby is that the connector can be made of the same material as the reinforcing material in a relatively simple manner.

According to a further preferred embodiment of the invention, the hooked cross-connectors have provided in the centre thereof a curved bend or like means which is intended to be gripped by the suspension means and positioning means when suspending and positioning the cage in the form or mould, preferably through the intermediary of separate holders, e.g. in the form of angle pins, incorporated in said means. The main advantage afforded by this embodiment is one relating primarily to manufacture. The bends can be made readily and rationally in conjunction with forming the hook shaped bends in the ends of the cross-connectors.

The invention also relates to a method for manufacturing a reinforcing cage or the like of the aforedescribed kind. The method is characterized by the steps set forth in the following Claim 5.

The invention will now be described in more detail with reference to the accompanying drawings, in which

Figure 1 illustrates a complete reinforcement cage constructed in accordance with the invention;

Figure 2 illustrates a preform reinforcing cage without the cross-connectors; Figure 3 illustrates schematically a reinforcing mat intended for conversion into the reinforcing cage of Figure 2 ;

Figure 4 illustrates schematically the procedure followed in principle when converting the mat illustrated in Figure 3 into the cage illustrated in Figure 2;

Figure 5 illustrates the complete reinforcing cage of Figure 1 inserted into a mould or form and secured to the surrounding moulding material with the aid of a positioning and securing rod; and Figure 6 illustrates a moulded reinforcing structure with embedded reinforcement.

Figure 1 illustrates a completed reinforcing cage intended for reinforcing floor and ceiling slabs made of steam-cured light-weight aerated concrete. The cage includes a first group of reinforcing irons or rounds 1 intended for reinforcing the top edge or side surface of a respective floor or ceiling slab, and a second group of reinforcing irons or rounds 2 intended for reinforcing the bottom edge or side surface of the same slab. The locations of the reinforcing irons in the finished slab of steam-cured light-weight con crete are shown in Figure 6. The groups of reinforcing irons 1 and 2 are held together at their respective ends, by means of transverse stirrups 3, 4 each of which has two legs 5, 6 and a web 7, and has the form of an upstanding U when seen in the position illustrated in the drawings. The reinforcing irons are welded to respective stirrups in some suitable manner. The upper ends of the transverse stirrups 3, 4 are held together by cross-connectors 8. Each cross-connector 8 is provided at each end thereof with a hooked portion 9 and has a curved bend 10 located in the centre thereof. Each hooked portion 9 engages around an associated leg 5 of a respective transverse stirrup 3, 4. The cross-connecters 8 hold together the legs 5, 6 of the stirrups 3, 4 against the action of a sprung restoring force, thereby to afford good stability to the construction and to form a mechanically rigid system which is fully closed when seen in cross- section and which will not result in undesirable movement in the finished slab. The web 7 of the transverse stirrups 3, 4 presents a small U-shaped member 11 which is welded to the web 7 at a location vertically beneath the curved bend 10 and which together with a contigous part of the web forms a ring 11 for accomodating a positioning and securing rod 12 (vide Figure 5) intended to form means for fixating and suspending the reinforcing cage in a mould or form.

Figure 2 illustrates the state of the reinforcing cage shown in Figure 1 prior to attaching the cross-connectors 8. It will be seen that in this prior state of the cage the legs 5, 6 of the transverse stirrups are splayed apart. When attaching the cross-connectors 8, the legs 5, 6 are urged towards each other against the action of an inherent spring restoring force, to a position in which the hook-shaped bends 9 are able to engage the end portion of respective leg 5 or 6, in order to couple said portions in a sprung or spring-biassed position. This outward splaying of the legs 5, 6 enables the relaxed reinforcing cages to be stacked one inside the other, thereby facilitating transportation of the cages, among other things.

Figures 3 and 4 illustrate together the method of constructing the cage pre-form illustrated in Figure 1, which is capable of being brought to a sprung state. As shown in Figure 3, when practicing the method according to the invention two groups of reinforcing irons or rounds are placed in the form of a mat, of which groups a first contains the irons 1 intended to reinforce the top side surface or edge surface of the finished reinforced slab of steam cured aerated concrete, and the second group contains the irons 2 intended to reinforce the bottom side or edge surface of said slab. Cross-pins 13, which ultimately form the transverse stirrups 3, 4 in the finished reinforcing cage, are then placed on top of the resultant "mat" and welded firmly to the reinforcing rods at their points of intersection with the pins. The rigid mat of reinforcing irons 1, 2 and cross-pins 13 is then bent mechanically, with the aid of a suitable shaping bar 18 which is placed between the furthest right-hand reinforcing iron in the group of top surface reinforcing irons and the furthest left-hand iron in the group of bottom surface reinforcing irons. With the aid of a suitable tool, a force is then applied to each end of the cross-pins 13 in the direction of the arrows 14, such as to deform the rigid mat to the shape illustrated in Figure 4. "Because the rigid mat is deformed with the structural components thereof in a cold state, the resultant reinforcing cage obtains "elastic memory properties", since the legs 5, 6 of the transverse stirrups with the reinforcing irons of both groups securely attached thereto are imparted a restoring spring force which urges the legs back to the position illustrated in Figure 2. The legs 5, 6 of the transverse stirrups are forced towards one another against the action of this restoring force and are held in the sprung or springbiassed position illustrated in Figure 1 with the aid of the cross-connectors 8, so as to provide the cage configuration illustrated in Figure 1.

When the reinforcing cage is used in the manufacture of a reinforced concrete structure, it is placed in a form or mould 15 intended for receiving a light-weight aerated concrete producing material, in accordance with Figure 5. The cage is positioned in the mould by suspending the cage within the interior of said mould with the aid of the positioning and securing rods 12, which are brought into engagement with the ring 11 on the web 7 of one of the transverse stirrups 3 or 4, and with the curved bend 10 on a respective cross-connector 8. The construction is secured with the aid of an angle pin (not shown) which is provided on respective positioning rods 12 and against which the curved bend 10 rests. As illustrated in Figure 5, the positioning rods 12 are also provided at their upper ends with a similar angle pin 16. This pin is intended to rest against a bar 17 which bridges to two side walls of the mould 15. The mould 15 is now filled with a light-weight aerated concrete forming material, i.e. in practice a material comprising an aqueous slurry of one or more silica-containing materials, e.g. sand, and one or more hydraulic binders, such as Portland cement or hydraulic lime, and powdered aluminium, the ability of the material to expand being dependent on the reaction of the aluminium powder with the alkaline constituants of the hydraulic binder while generating hydrogen gas, whereupon the mixture swells up. Subsequent to the mixture expanding, the mixture begins to solidify and ultimately becomes sufficiently stiff to support the reinforcing cage unaided. The supporting bar 17 is now removed and the positioning and securing rods 12 are rotated about their longitudinal axes with the aid of the angle pin 16, to a position in which the first-mentioned angle pins (not shown), which have hitherto supportingly engaged respective support members 11 on the cross-connectors 8, are out of engagement with said members, therewith to enable the positioning rods 12 to be readily withdrawn from the cast material. Upon completion of the moulding operation and the aforesaid solidifying process associated therewith, the mould is stripped and the moulded structure is loaded into an autoclave, where it is steam cured. In practice, a mould will accommodate a multiple of reinforcing cages, and the resultant casting may be cut into smaller elements. Irrespective of whether the moulded structure is cut or not, the final steam-cured gas concrete structure can be used as a structural component in various kinds of building constructions. Because the reinforcing cage is fully continuous when seen in cross-section, the cage is stronger than the earlier known cages, with less risk of the steam-cured material cracking, at the same time as the working operation in which the means for effecting suspension of the positioning rods at the top of the cage can be formed on the cross-connectors 8 during their manufacture, there being no difficulty in forming, at the same time, a curved bend 10 in respective transverse stirrups for securing the temporary engagement of the positioning rods 12 therewith during the stage in which the reinforcing cage is not surrounded by gas concrete material or a material which is not sufficiently solid to support the cage.

Claims

1. A reinforcing cage or like device intended to be positioned in a mould for moulding artificial stone materials, comprising a first group of elongated, mutually parallel reinforcing irons (1) for supporting the upper edge or side surface of a slab of cast artificial stone material, and a second group of elongated, mutually parallel reinforcing irons (2) for reinforcing the bottom edge or side surface of the same slab, the groups of reinforcing irons being held together by transverse stirrup-like connectors (3,4), characterized in that the legs (5, 6) of the transverse stirrups (3,4) are held in a sprung or spring-biassed state with the aid of cross-connectors (8) or like devices provided with hooks (9).

2. A reinforcing cage according to Claim 1, characterized in that the legs (5, 6) of the transverse stirrups (3,4) are urged away from one another in the sprung position of said legs.

3. A reinforcing cage according to Claim 1 or Claim 2, characterized in that the cross-connectors (8) provided with hooks (9) comprise reinforcing irons which have been bent to form a hook at each end thereof.

4. A reinforcing cage according to Claims 1-3, characterized in that the cross-connectors (8) or like devices provided with hooks (9) present a curved bend (10) which is intended to engage suspension and positioning means (12) when suspending and positioning the reinforcing cage in the mould.

5. A method for manufacturing a reinforcing cage or the like intended to be placed in moulds for moulding artificial stone materials, particularly light-weight concrete. comprising a first group of elongated, mutually parallel reinforcing irons (1) intended for reinforcing the upper edge or side surface of a slab moulded from said artificial stone material, and a second group of elongated, mutually parallel reinforcing irons (2) intended for reinforcing the bottom edge or side surface of the same slab, the groups of reinforcing irons being held together by transverse stirruplike device (3, 4) and the legs (5,6) of the transverse stirrups (3, 4) being sprung or under spring-biass and held in their sprung state with the aid of cross-connectors (8) or the like provided with hooks (8), characterized by attaching the first group of elongated mutually parallel reinforcing irons (1) and the second group of elongated, mutually parallel reinforcing irons (2) to a plurality of cross-pins (13) which, subsequent to being bent, form transverse stirrups (3, 4), to form a mat; by pressing the mat against a shaping bar (18) or some other suitable shaping body in a zone between the first group (1) and the second group (2) of reinforcing irons to form bends in the cross pins and to form the transverse stirrups (3,4) of the reinforcing cage; and by bringing the cross-connectors (8) provided with hooks (9) into their intended respective position.