| CLAIMS 1. A shutter spacer unit comprising a shutter contact portion a reinforcement contact portion and at least one connecting section connecting the shutter contact portion to the reinforcement contact portion. 2. A shutter spacer unit as claimed in claim 1 , wherein the connecting section is configured to ensure that the shutter contact portion (51) and the reinforcement contact portion (52) are in separate planes from each other defining a desired distance between the internal surface of the shutter material and the exterior of the reinforcement cage. 3. A shutter spacer unit as claimed in claim 1 or claim 2, which comprises a single shutter contact portion (51 ), two reinforcement contact portions (52) and two connecting sections (53). 4. A shutter spacer unit as claimed in any one of the preceding claims, wherein the shutter contact portion (50) is made of plastic. 5. A shutter spacer unit as claimed in any one of the preceding claims, wherein the reinforcement contact portion (52) is made of steel. 6. A shutter spacer unit as claimed in any one of the preceding claims, wherein the connecting section (53) is made of steel and is partially covered by the material of the shutter contact portion (50). 7. A shutter spacer unit as claimed in any one of the preceding claims, wherein the shutter contact portion (51) reinforcement contact portion (52) are in contact planes that are substantially parallel to each other. 8. A shutter spacer unit as claimed in any one of the preceding claims , wherein the shutter contact portion (51), reinforcement contact portions (52) and connecting sections (53) are in an aligned plane (T) perpendicular to the contact plane. 9. A shutter spacer unit as claimed in any one of the preceding claims, wherein the shutter contact portion (51) comprises a substantially flat elongate contact surface. 10. A shutter spacer unit as claimed in any one of the preceding claims, wherein the reinforcement contact portions (52) are not located beneath the shutter contact portion (51), but extend from the periphery of the shutter contact portion (51) and are connected thereto via the connecting sections (53). 11.A shutter spacer unit as claimed in any one of the preceding claims, wherein the spacer unit is preferably made of two components comprising a steel bar (57) and a formed plastic component (58). 12. A shutter spacer unit as claimed in claim 11 , wherein the formed plastic component (58) has a flat section, which constitutes the shutter contact portion (51) and a plastic tube like section (55) located underneath and extending from this contact portion (51). 13. A shutter spacer unit as claimed in claim 12, wherein the steel bar (57) is located within the bore of the plastic tube section (55) and protrudes from either end of the plastic tube. 14. A shutter spacer unit as claimed in any one of claims 11 to 13, wherein the bar (57) and tube (55) are bent to the desired angles and lengths to provide the connecting sections (53). 15. A shutter spacer unit as claimed in any one of the preceding claims, wherein the angle of the connecting sections (53) relative to the shutter contact surface is less than 85 degrees, preferably less than 75 degrees, more preferably less than 65 degrees and is within the range of 15 to 85 degrees, preferably within the range 25 to 75 degrees and most preferably is within the range of 30 to 65 degrees. 16. A reinforced sacrificial shutter unit comprising shuttering material, reinforcement and a plurality of spacers according to any one of claims 1 to 15, permanently secured between the reinforcement and the shuttering material. 17. A shutter unit reinforcement cage comprising a plurality of spacer units according to any one of claims 1 to 15, permanently secured to the cage structure. 18. A ground beam shutter, a pile cap shutter, comprising a shutter as claimed in claim 16 or a shutter unit reinforcement cage as claimed in claim 17. 19. A method for the manufacture of a reinforced sacrificial shutter unit as claimed in claim 16, which method comprises: selection of a reinforcement of the required dimensions and material for a given structural element, selection of the required number and dimension of spacers, permanently securing the spacers at the required locations and orientations to the reinforcement, and permanently securing the required shuttering material to the spacers. |
FIELD OF INVENTION
[0001] The invention concerns reinforced shutter systems for use in the construction industry for the preparation of structural elements and to methods of making such reinforced shutter systems.
BACKGROUND ART
[0002] Typically a structural element, such as pile cap formers and ground beams are formed by placing wooden or steel pre-made formers against reinforcing steel, pouring concrete to set and then removing the said formers, which can be re-usable. This method has a heavy skilled labour content.
[0003] Other non-traditional methods, which may be sacrificial, use polystyrene, polypropylene or steel mesh coated with plastic and can be installed around the reinforcing steel, backfilled with soil and left in position, after the concrete pour. This method, although quicker than traditional methods, still requires a certain amount of 'on-site' labour time and assembly by often inexperienced installers.
[0004] Examples of non-traditional systems and methods are provided in
EP0866196A1 and US2004/0093824A1.
[0005] However, at the present time there is no satisfactory pre- fabrication system for reinforced sacrificial shutters, which enables a particular reinforced shutter design to be easily and effectively manufactured remote from the site of installation and then easily transported and installed at the required site, with minimum levels of installation expertise. The current systems require onsite assembly often by inexperienced assemblers with problems of quality and expense resulting in delays and additional costs in building or structure erection. DISCLOSURE OF THE INVENTION
[0006] The present invention provides a prefabricated factory made unit, which is ready for instant installation upon arrival on-site. The system is able to utilise highly skilled labour during the manufacturing process to put in place a flexible reinforced shutter production line, which enables reinforced shuttering to be prepared to an extremely high standard at low costs to the installer. The skill level required during installation is reduced and the time required for onsite installation is reduced.
[0007] This present invention therefore provides a reinforced sacrificial shutter unit comprising shuttering material, reinforcement and a plurality of spacers permanently secured between the reinforcement and the shuttering material.
[0008] The number and location of the spacers are selected to provide a final unit that is rigid enough to be moved and transported to the installation site. The exact number and location will depend on the size and shape of the shuttering unit. Larger units will require a larger number of spacers and complex shutter structures may require a higher density of spacers to be located at higher load bearing parts of the structure. Another factor to be considered when selecting the number and location of spacers is the robustness of the shutter material to backfill when the unit is in the desired location and is being prepared for addition of concrete. If the shutter material is not held robustly and rigidly in place it may be deformed during the backfill process resulting in uneven encapsulation of reinforcement within the concrete structural element and a dimensionally non-uniform structure. This effect may to a certain degree be alleviated by using inherently more rigid shutter material during manufacture of the unit. Thus the required rigidity for the final unit may be achieved through appropriate material selection for the shutter and/or location and density of permanent spacers. [0009] When permanently attached to the reinforcement and the shutter the spacer defines a predetermined distance between the exterior of the reinforcement and the inner surface of the shutter material. It is often a requirement that this distance may be within a minimum or a maximum to ensure the correct thickness of concrete encapsulating the concrete impregnated reinforcement. For any particular design of reinforced shuttering unit the dimensions of the spacers are selected to provide the required distance between the exterior of the reinforcement and the inner surface of the shutter material and therefore resulting thickness of concrete encapsulation.
[0010] The steel reinforcement is permanently fixed to the required specification and number of spacers at the required locations by and suitable means, which is dependent on the material properties of the reinforcement and the spacer. So for example when the reinforcement is stainless steel the spacer may also be stainless steel and permanently secured to the reinforcement by mechanical means such as welding.
[0011] The shuttering material may be any suitable material capable of providing the required rigidity after assembly of the unit and which may be used as a sacrificial shutter. A sacrificial shutter is a shutter, which is not removed after the concrete has been introduced and is set, but is left in-situ. The shutter remains in-situ and in certain cases this may offer further advantages over temporary/removable shuttering. The shuttering may be manufactured from biodegradable materials such as strong cardboard or compressed paper/or wood based products, that degrade in an environmentally acceptable manner. Whilst being sacrificed during use these materials are not permanent and eventually degrade. In a preferred embodiment the shuttering is manufactured from a permanent material that does not substantially degrade or lose its properties when left in-situ. One material meeting these requirements is plastic. Preferably, the plastic is in the form of what is known as corrugated or fluted plastic sheets. Corrugated/fluted plastic is a well-known material having two parallel facing sheets and spaced, integral interconnecting ribs between the facing sheets. The plastic sheet material can be easily extruded from a variety of plastic resins such as polyethylene, polypropylene, modified polypropylene and the like. For the purposes of the present invention any reference to corrugated/fluted plastic is a reference to a material comprising at least two parallel facing sheets of some plastic composite, having spaced, integral interconnecting ribs between each sheet. A further preferred arrangement is when the fluted sheet comprises two parallel layers fluted material this consists of three sheets of plastic, one sheet sandwiched between two outer sheets and connected to the two outer sheets by spaced, integral interconnecting ribs. This material may also be obtained using extrusion techniques. The preferred material is plastic and a preferred plastic is polypropylene, since in its extruded form it exhibits the necessary mechanical properties and is extremely cost effective to manufacture. A further advantage is that plastics and especially polypropylene are resistant to attack from a wide range of chemicals and minerals, making shutters, manufactured in polypropylene, suitable for use in contaminated ground. It is possible to treat the shutters in order to provide enhanced properties, although this increases the cost of manufacture. It will be appreciated that other plastics are within the scope of the invention.
[0012] The shuttering material e.g. plastic shutter is mechanically and permanently fixed to the reinforcement via the spacers. This completed prefabricated unit can also be sealed to be gas and waterproofed to become part of a gas and or water proofing system. Once this is completed, the unit may be handled, transported to the required site and lifted into position as part of the construction foundation design plan.
[0013] As an example the method of the present invention allows a complex and extensive foundation system to be designed and manufactured remotely from the site and supplied to the site in a modular form. This foundation system may comprise a series of units according to the present invention that are manufactured remotely, transported to the site and arranged in-situ to provide a complex foundation. Once the units are installed into the required position, it is a very quick and simple exercise to mechanically connect the steel reinforcements and the shutter material in adjacent units in-situ, thus completing the structural foundation.
[0014] In a further aspect the present invention provides a method for the manufacture of a reinforced sacrificial shutter unit, which method requires:
a) selection of a reinforcement of the required dimensions and material for a given structural element, b) selection of the required number and dimension of spacers, c) permanently securing the spacers at the required locations and orientations to the reinforcement, and d) permanently securing the required shuttering material to the spacers.
[0015] It is preferred that a) to d) are steps carried out in sequence.
[0016] It is preferred that the reinforcing material is steel but this could be another material not unlike steel, to create the predesigned configuration i.e. reinforcement cage, as specified by the structural engineer. This may be for a pile cap former, but it can also be a ground beam former or any other structural element former. This system provides a pre-made plastic shutter unit, with integral steel reinforcement. The steel is made and fixed, according to the design specification. The shutter material may be plastic, may be polypropylene or a modified polypropylene. The shutter is to form a structural element, which may be a pile cap, a ground beam or other pre-designed element.
[0017] It is preferred that the spacer unit is as depicted in Figure 8. Other types of spacer may be used. They may be linear type spacers, or they may be other forms of spacers, available in the construction products market place as long as they may be permanently secured to the reinforcement and the shutter to provide the required robustness to enable transportation of the unit to the site for installation. [0018] The present invention further provides a shutter spacer unit comprising a shutter contact portion a reinforcement contact portion and at least one connecting section connecting the shutter contact portion to the reinforcement contact portion.
[0019] The present invention further provides a shutter unit reinforcement cage comprising a plurality of spacer units permanently secured to the cage structure.
[0020] The shutter material may be used as extruded if it is of the correct dimensions or there may be a need to cut, crease and/or form the dimensionally correct plastic shutter material and attach this firmly to the reinforcement cage, by a mechanical method.
DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to various specific embodiments of the invention as shown in the accompanying diagrammatic drawings, in which:
FIG. 1 shows a schematic end view of a reinforced sacrificial shutter unit embodiment according to the present invention as manufactured,
FIG. 2 shows a schematic top plan view of the reinforced sacrificial shutter unit of Fig.1 ,
FIG. 3 shows the reinforced sacrificial shutter unit as shown in FIG. 1 in-situ,
FIG. 4 shows a schematic of an encapsulated unit according to the present invention, FIG. 5 shows a schematic end view of a further reinforced sacrificial shutter unit embodiment according to the present invention as manufactured,
FIG. 6 shows the reinforced sacrificial shutter unit as shown in FIG. 5 in-situ,
FIG. 7 shows a schematic detailed side profile of the spacer according to the present invention in-situ,
FIG. 8 (a) to (d) shows various orientations of a spacer according to the present invention, and
FIG. 9 (a) shows a spacer unit having an alternative alignment to FIG. 8(d),
DETAILED DESCRIPTION OF THE INVENTION
[0021] With reference to Fig.1 , the illustrated reinforced sacrificial shutter unit (1) consists of two parallel "L" shutter side panels (2.2 1 ), a stainless steel reinforcement cage (3) and six spacer units (4) according to the invention. Other spacer units present are not shown as they are located behind those illustrated. The "L" shaped shutter side panels (2, 2') are secured to the cage (3) via the spacer units (4). The spacer (4) illustrated has a shutter contact portion (5) that is in contact with the shutter (2.2') and is permanently secured to that shutter (2,2') via securing screws (6). The spacer (4) illustrated has a reinforcement contact portion (7), which is in contact with the cage (3) and is permanently secured to the cage (3), via welds at the points of contact. The shutter contact portion (5) and the reinforcement contact portion (7) are connected to each other via a connecting section (8). In this example the shutter contact portion (5) is made of plastic and the reinforcement contact portion (7) is made of steel. The connecting section (8) is made of steel and is partially covered by the shutter contact portion (5) (see Figure 8 discussion below). [0022] With reference to Fig.2, the reinforced sacrificial shutter unit (1) of
Fig.1 is shown in top plan view and more clearly shows the orientation and features of the spacer unit (4) when secured to the shutter side panels (2,2') and stainless steel reinforcement cage (3). The reinforcement cage (3) is a complex welded structure of stainless steel bars and rods; in these Figures only the contact edges are illustrated for clarity. As can be seen in this embodiment the spacer (4) has a single shutter contact portion (5) that is in contact with the shutter (2.2') and is permanently secured to that shutter (2,2') via securing screws (6). The illustrated spacer (4) has two reinforcement contact portions (7), which are connected to the central shutter contact portion (5) by connecting sections (8). The relative position of the shutter contact portion (5) to the reinforcement contact portions (7) is such that the connecting sections define an angle (x) relative to the shutter contact portion (5), which is not 90 degrees; as illustrated it is approximately 45 degrees in this embodiment. The shutter unit (1) of Figs 1 and 2 shows in section a ground beam. However, it is possible to use shutters of the present invention to produce other structural features, such as pile caps. The shutter may be located in a blinded, backfilled trench. Subsequently, concrete is poured into the shutter, which, once the concrete has set, remains in place. Other forms of shuttering are also with the scope of the invention.
[0023] With reference to Fig.3, the reinforced sacrificial shutter unit (1) of
Fig.1 is shown in-situ. The manufactured unit (1) has been transported to an installation site, which has been prepared for its installation. The bed (11) of the installation is compacted soil or a prepared concrete surface onto which has been laid a base plate (10), which may be manufactured from the same material as that used for the shuttering panels (2,2'). The dimensions of the base plate (10) are such that there is overlap with the lower surfaces of the "L" shaped shutter panels (2, 2'). To complete the proofing of the unit a sealant (9) may be used between the contact points of the shutter side panels (2, 2') and the base plate (10). As an alternative the base plate (10) could be adhesively secured to the shutter side panels (2, 2') during manufacture of the unit (1) before it is transported to the installation site. The installation of Fig.3, is easy to install and is robust, which will resist heavy soil backfill, when the unit is placed in the ground
[0024] In a further embodiment as illustrated in Figs 4, the shutter unit may also be a completely encapsulated unit (20) meaning that all the sides (21 , 22, 23 and 24) and base plate (25) are integral with the top surface (26) open for the pouring of concrete into the unit. This unit (20) when completed, after fixing the plastic shutter material to the internal reinforcement cage (27) with the spacers of the present invention, will be a sturdy and strong unit, which will be portable and easily transported to the building site. It will be completed to the required specification and dimensions, that when installed into the foundation plan and concrete or other settable material is poured into the shutter unit will form a completed structural element, which may be a pile cap, or a ground beam or any other structural unit.
[0025] In a further embodiment as illustrated in Figs 5 and 6, the shutter unit (30) may be manufactured so as to obviate the need for a separate base plate. In this embodiment the shutter (31) is prepared from a single sheet of plastic material, which is creased at edge points (32 and 33) and bent to the required shape for the structural element. This unit (30) avoids the need for sealant of the shutter sides to the base plate as used in Fig 1 and 2. Apart from this difference all other features of Figs 5 and 6 are the same as Figs 1 and 2.
[0026] When protection against mineral contamination in the ground is required the units may be effectively sealed, either whilst the fabrication method is being undertaken and/or too adjacent units in-situ. They may also be effectively sealed and used as part of a gas or waterproofing system, as may be required by the structural or ground engineer's specification.
[0027] Fig. 7 shows one method of fixing and permanently securing the shuttering material (40) to the steel reinforcement (41), via a suitable spacer unit (42) according to the present invention. The spacer unit (42) has a shutter contact portion (43) that is in contact with the shutter (40) and is permanently secured to that shutter (40) via securing screws (44) in conjunction with a washer (45) in this example. The spacer unit (42) has a reinforcement contact portion (46), which is in contact with the cage (41) and is permanently secured to the cage (41), via welds at the points of contact. The shutter contact portion (43) and the reinforcement contact portion (46) are connected to each other via a connecting section (47). In this example the shutter contact portion (43) is made of plastic and the reinforcement contact portion (46) is made of steel. The connecting section (47) is made of steel and is partially covered by the shutter contact portion (43). Other methods of securing the shutter material to the spacer are within the scope of the invention. This Fig shows a screw or this may be another fixing product such as a stud, fixed through the shutter material (40) and into the spacer unit (43). When the contact portion is plastic it may be fixed to the plastic shutter material vii adhesive bonding or other non-mechanical but permanent methods such as plastic welding techniques.
[0028] Fig. 8 (a) to (d) shows the preferred spacer unit (50) of the present invention. Fig. 8 (a) is a side view, FIG. 8 (b) is a top view in the direction of arrow (Y), FIG. 8 (c) is a bottom view in the direction of arrow (Z) and FIG. 8 (d) is an end view in the direction of arrow (S). The spacer (50) has a shutter contact portion (51) that is configured for effective contact with a shutter surface and is manufactured from material, which enables effective permanent securing of the shutter material to the contact portion (51). The spacer (50) also has a reinforcement contact portion (52), which is configured for contact with a reinforcing cage and is capable of being permanently secured to the cage. The shutter contact portion (51) and the reinforcement contact portion (52) are connected to each other via a connecting section (53). The connecting section is designed and configured to ensure that the shutter contact portion (51) and the reinforcement contact portion (52) are in separate planes from each other thus defining a desired (P) distance between the internal surface of the shutter material and the exterior of the reinforcement cage to ensure the correct thickness of concrete encapsulates the reinforcement cage. This is specified particular to every steel reinforced structural element, by the structural engineer, who designs each particular structural element, stating the thickness of concrete required to protect the integrity of the steel reinforcement. In this embodiment there is a single shutter contact portion (51), two reinforcement contact portions (52) and two connecting sections (53). In this embodiment the shutter contact portion (50) is made of plastic and the reinforcement contact portion (52) is made of steel. The connecting section (53) is made of steel and is partially covered by the material of shutter contact portion (50). The spacer may be made of a single material if this material may be permanently secured to the reinforcement cage and shutter material, which may be steel, may be plastic or it may be a combination of materials. It should be understood that simply tying of the spacer to these components is not considered to be permanent secure attachment of the spacer to these components. The method of attachment should be such that there is intimate physical contact of all contact surfaces and that the attachment is robust enough to prevent relative movement of the components. In a preferred embodiment the shutter contact portion (51) reinforcement contact portion (52) are in planes that are substantially parallel to each other. It is preferred that there are at least two reinforcement contact portions (52) and at least two connecting sections (53). There may for example be two reinforcement contact portions (52) and two connecting sections (53) at each end of the shutter contact portion (51), providing four of each in total. In a preferred embodiment the shutter contact portion (51 ), reinforcement contact portions (52) and connecting sections (53) are in an aligned plane (T) as illustrated in FIG . 8 (d). This plane is perpendicular to the contact planes, which are the planes of contact between the spacer and the shutter and/or reinforcement cage. It is possible that the two reinforcement contact portions (52) and the connecting sections (53) are not in such an alignment as illustrated in FIG. 9. It is preferred that the reinforcement contact portions (52) are elongate extensions from the connecting sections (53). In a preferred embodiment the reinforcement contact portions (52) are steel bars. It is preferred that the shutter contact portion (51) comprises a substantially flat elongate contact surface. This contact surface preferably provides larger contact surface than the contact surface between the reinforcement contact portions (52) and the reinforcement cage. The large contact surface for the shutter contact portion (51) aids in bracing the secured shutter in fixed position relative to the reinforcement cage. It is preferred that the reinforcement contact portions (52) are not located beneath the shutter contact portion (51), but extend from the periphery of the shutter contact portion (51) an dare connected thereto via the connecting sections (53). The spacer unit is preferably made of two components comprising a steel bar (57) and a formed plastic component (58). The formed plastic component (58) has a flat section which constitutes the shutter contact portion (51) and a plastic tube like section (55) located underneath and extending from this contact portion (51). The steel bar (57) is located within the bore of the plastic tube section (55) and protrudes from either end of the plastic tube. The bar (57) and tube (55) are bent to the desired angle and length to provide the connecting sections (53). This ensures that the bar (57) is securely engaged with the plastic component (55) and that the correct orientation of components is achieved for the spacer. In this arrangement a shoulder (59) may also be produced; this can also be used to fix into, by screwing or other means, to secure the shutter material to the spacer unit. It is preferred that the angle of the connecting sections (53) relative to the shutter contact surface (angle X in FIG. 2) is less than 85 degrees, preferably less than 75 degrees, more preferably less than 65 degrees and is within the range of 15 to 85 degrees, preferably within the range 25 to 75 degrees and most preferably is within the range of 30 to 65 degrees.
[0029] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.