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WO2013014157A1 - Dalle de béton à noyau creux - Google Patents

Dalle de béton à noyau creux Download PDF

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Publication number
WO2013014157A1
WO2013014157A1 PCT/EP2012/064502 EP2012064502W WO2013014157A1 WO 2013014157 A1 WO2013014157 A1 WO 2013014157A1 EP 2012064502 W EP2012064502 W EP 2012064502W WO 2013014157 A1 WO2013014157 A1 WO 2013014157A1
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WO
WIPO (PCT)
Prior art keywords
hollow
concrete slab
concrete
slab
core concrete
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2012/064502
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English (en)
Inventor
Mark Jardine
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Poundfield Products Ltd
Original Assignee
Poundfield Products Ltd
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Filing date
Publication date
Application filed by Poundfield Products Ltd filed Critical Poundfield Products Ltd
Publication of WO2013014157A1 publication Critical patent/WO2013014157A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B7/00—Moulds; Cores; Mandrels
    • B28B7/16—Moulds for making shaped articles with cavities or holes open to the surface, e.g. with blind holes
    • B28B7/18—Moulds for making shaped articles with cavities or holes open to the surface, e.g. with blind holes the holes passing completely through the article
    • B28B7/186—Moulds for making shaped articles with cavities or holes open to the surface, e.g. with blind holes the holes passing completely through the article for plates, panels or similar sheet- or disc-shaped objects, also flat oblong moulded articles with lateral openings, e.g. panels with openings for doors or windows, grated girders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/0006—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects the reinforcement consisting of aligned, non-metal reinforcing elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
    • B28B23/04—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed
    • B28B23/06—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed for the production of elongated articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B7/00—Moulds; Cores; Mandrels
    • B28B7/28—Cores; Mandrels
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00—Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/02—Load-carrying floor structures formed substantially of prefabricated units
    • E04B5/04—Load-carrying floor structures formed substantially of prefabricated units with beams or slabs of concrete or other stone-like material, e.g. asbestos cement
    • E04B5/043—Load-carrying floor structures formed substantially of prefabricated units with beams or slabs of concrete or other stone-like material, e.g. asbestos cement having elongated hollow cores
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/02—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials
    • E04C2/04—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of concrete or other stone-like material; of asbestos cement; of cement and other mineral fibres
    • E04C2/06—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of concrete or other stone-like material; of asbestos cement; of cement and other mineral fibres reinforced

Definitions

  • This invention relates to hollow-core concrete and methods for manufacturing hollow-core concrete.
  • Prefabricated hollow-core concrete slabs have been used for many years in the construction of flooring in multi-storey buildings.
  • the concrete slabs are pre-stressed along at least their lower side by tensioned steel wire rope so as to help counterbalance the tensional forces acting on the lower side of the concrete slabs when in use.
  • the term "hollow-core” refers to voids in the concrete that reduce the weight of the slabs, allowing them to span several metres whilst still being able to support large loads.
  • hollow-core concrete slabs are formed with multiple tubular voids that extend lengthwise through a concrete slab.
  • hollow-core concrete slabs are made by a slip-forming process that involves the extrusion of semi-dry concrete into beds laid up with pre- tensioned steel cable.
  • Hollow-core concrete made by the extrusion or slip-forming process is typically produced as a single long slab in steel beds around 120-150m in length.
  • the concrete is laid in a single pass by a large hopper that simultaneously extrudes, compacts and vibrates the concrete as it moves along the bed.
  • a set of metal augers are driven through the concrete beneath the hopper so as to form a set of hollow channels. This process suffers from a number of problems.
  • the extrusion process can only be used with a semi-dry concrete mix. This leads to an enormous amount of abrasion on the machine parts, particularly on the metal augers that are each driven through the entire length of the beds in order to form the hollow channels. Often these augers last only a few runs before needing to be replaced. Furthermore, the extrusion process forms a continuous long slab which must be cut into slabs of the required length by a diamond circular saw. This adds further expense since the saws must also be regularly replaced and are themselves relatively costly. In fact, it is estimated that as much as a third of the cost of producing hollow-core concrete is due to the cost of replacing the metal parts of extrusion machines and ensuring that skilled engineers are on- hand to perform the constant replacement of parts.
  • the extrusion machine requires very high power motors in order to drive the semi-dry concrete mix into the beds, to vibrate the concrete in the beds and to drive the hopper itself along the bed.
  • Factories producing hollow-core concrete slabs by extrusion are therefore very energy intensive.
  • the poor quality surface finish also affects the side walls of the concrete slab, with further degradation in quality being due to slippage of the hopper as it moves along the bed. This results in concrete slabs that have very uneven edges that do not neatly abut adjacent slabs when laid in-situ. A significant proportion of slabs are scrapped by some manufacturers due to this problem. Even if the slabs have edges of good enough quality to be used, it will typically be necessary to prepare the edges of slabs prior to use at the building site to ensure that adjacent slabs lie flush to one another. This is usually accomplished through the use of cutting equipment. Fillers are often used to plug any remaining gaps.
  • each hollow-core slab cut from a continuous slip-formed slab are also of very low quality. Since the long steel beds in which the slabs are formed are very expensive, the diamond circular saws are arranged to cut only to within around 10mm of the bed so as to avoid damaging the steel surface. This means that each hollow-core slab must be literally snapped-off, leaving a rough edge that it is often necessary to prepare prior to use at the building site.
  • a hollow-core concrete slab comprising:
  • a plurality of substantially parallel hollow channels extending through the slab, the hollow channels being sandwiched between first and second major surfaces of the slab; and a layer of inert pliable filaments comprising a first set of filaments that are oriented transversely to the hollow channels and lie adjacent to the hollow channels between the hollow channels and the first major surface of the slab.
  • the layer of inert pliable filaments passes through the roof of each hollow channel.
  • the layer of inert pliable filaments lies closer to the hollow channels than to the first major surface of the slab.
  • the layer of inert pliable filaments comprises a second set of filaments oriented transversely to and interconnecting the first set of filaments so as to form a mesh.
  • the mesh is a flat mesh having openings at least 40mm across, and most preferably at least 50 mm across.
  • the mesh is a plastic mesh having a weight of less than 150 g/sq. m and preferably less than 100 g/sq. m.
  • the filaments are polypropylene or nylon filaments.
  • the ratio of the total cross-sectional area of the plurality of hollow channels to the gross cross-sectional area of the concrete slab is at least 15%, preferably 35%, and most preferably at least 38%.
  • the hollow-core concrete slab comprises a plurality of tensioned steel cables between the hollow channels and the second major surface of the slab.
  • at least some of the tensioned steel cables project out of the ends of the concrete slab by at least a few centimetres.
  • the hollow-core concrete slab does not comprise any tensile reinforcement between the hollow channels and the first major surface of the slab.
  • the hollow-core concrete slab comprises aggregate having a Mohs hardness of at least 4, preferably at least 5, more preferably at least 6, and most preferably at least 7.
  • the hollow-core concrete slab is a wet-formed product.
  • the average surface roughness of the second major surface is less than a millimetre.
  • Figure 1 is a cross-sectional view of a mould comprising a completed concrete slab in accordance with the present invention.
  • Figure 2 is a top-down view of the same mould and slab as the void formers are removed.
  • Figure 3 is a perspective view of the same mould and slab once the void formers have been removed.
  • Figure 4 is a perspective view of an end piece according to a preferred embodiment of the present invention.
  • the present invention relates to a new process for manufacturing hollow-core concrete slabs that overcomes the problems associated with conventional processes.
  • Figure 1 is a cross-sectional view of a mould 100 comprising a completed concrete slab 101 in accordance with the present invention.
  • Figure 2 is a top- down view of the same mould and slab as the tubes 102 are removed.
  • Figure 3 is a perspective view of the same mould and slab once the tubes 102 have been removed. The formation of the concrete slab in accordance with the present invention will now be described with reference to these figures.
  • Mould 100 comprises a metal bed and side walls 103 and 104 into which end- pieces 201 and 202 (not shown in figures 1 and 2) can be positioned so as to define concrete slabs of the desired length.
  • the side walls may include various features 109 in order to define lips and indentations in the sides of the concrete slabs and facilitate the interlocking of adjacent slabs when in situ.
  • mould 100 is long enough to allow several concrete slabs each several metres in length to be accommodated in various stages of manufacture.
  • the end-pieces 201 and 202 are preferably not fixed into the bed of the mould so as to allow them to be positioned at any point along the bed.
  • the end pieces can be made of steel or a similar dense metal but their structure is not important providing they are capable of supporting a plurality of tubes for defining voids in a concrete mix poured into the mould.
  • mould 100 Prior to pouring the concrete, mould 100 is prepared by suspending between the end pieces 201 and 202 the tubes 102 that are to define the hollow channels 300 in the concrete slab. This can be achieved by providing guide holes in the end pieces to receive the tubes.
  • the concrete slab is to comprise steel reinforcement, then rebar or tensioned steel cable 105 can be also placed in the mould, typically below the level of the tubes 102.
  • pre-stressed concrete flooring slabs generally comprise tensioned steel cables arranged in the lower portion of the slab so as to help counterbalance the tensional forces experienced by the lower portion of the concrete slab when in use.
  • Tensioned steel cable 105 can be provided in mould 100 in the conventional manner by suspending tensioned steel cables along the length of the mould (the cables could be tensioned by a winch at one end of the mould).
  • the steel cable passes through end-pieces 201 , 202 and the end pieces are fixed relative to the steel cable such that (a) the steel cable is supported and does not significantly sag due to its weight between the two end pieces, and (b) the end pieces are held in position during pouring of the concrete. This can be achieved as shown in figure 4.
  • FIG. 4 illustrates the configuration of end pieces 201 and 202 in preferred embodiments of the present invention.
  • Each end piece comprises an upper part 405 and a lower part 404 (shown separately in figure 4).
  • Cut-outs 406 are provided in the lower part to receive the tubes 102 (not shown in figure 4), with corresponding cut-outs being provided in the upper part such that, when the upper part is brought together with the lower part as indicated by arrow 408, the upper and lower parts sandwich the tubes 102 and form a seal along edges 4 0. In this manner, the tubes are held in position by the end pieces but are not rigidly fixed to the end pieces.
  • Guide holes 403 are provided in lower part 404 through which tensioned steel cable 105 can pass through, and simple wedges 102 can be used to hold the steel cable in place relative to the lower part (and vice versa).
  • the wedges are forced under the steel cable so as to ensure that the steel cable passes through the uppermost region of the guide holes 403. This arrangement ensures that end piece and steel cables stay in their intended position during moulding.
  • the concrete slab is formed by the following steps:
  • the mould is filled up to approximately the level of the top of the tubes 102 (indicated by dashed line 107 in figure 1 ) so as to just cover the crown of the tubes.
  • the mould is partially filled up to a level above or below the top of the tubes that is within 30% of the diameter of the tubes (typically, within one or two inches).
  • the mould is filled up to at least the level of the top of the tubes.
  • Vibrating the concrete mix This could be by any means of vibration or agitation that drives air pockets from the mix and ensures that the concrete properly settles around the tubes other surfaces of the mould.
  • the vibration could be achieved by vibrating the mould and/or the tubes and/or through the use of a concrete vibrator such as a hand-held vibrating wand).
  • the concrete mix is vibrated by a concrete vibrator having a vibrating element that is small enough to pass between the tubes 102. It is particularly advantageous if the vibrating element is pushed through the concrete mix into contact with the mould base 1 10. This helps to drive air pockets away from the mould base and ensures that the lower major surface of the moulded concrete slab has a good quality smooth finish.
  • step 4 Vibrating at least the upper layer of concrete mix added in step 4. It is advantageous if this vibration step is performed by means of a vibrating board whose effect is to both vibrate the concrete mix and level-out the upper surface of the concrete mix (which will become the upper major surface of the concrete slab).
  • Extracting the tubes 102 from the mould by withdrawing the tubes substantially along their long axis so as to slide the tubes out of the concrete mix (this is shown in figure 2). This step can be performed immediately once the concrete has been poured and settled, which takes only minutes.
  • step 2 can be omitted and the concrete mix is vibrated at step 5 only. In other less preferable embodiments, step 2 can be retained but step 5 omitted.
  • the finished article is extracted fro the mould. This can be conveniently performed by arranging that one or both of the sides of the mould 103, 104 are hinged so as to allow the sides to be folded away and the moulded concrete slab to be lifted cleanly from the mould base 1 10.
  • the present invention allows concrete slabs to be rapidly formed from a wet concrete mix, yielding slabs of excellent surface quality.
  • the concrete mix is wet in the sense that it could not be used to make concrete slabs by the slip-forming process.
  • the concrete mix preferably has around 70 litres of water per cubic metre (with typically 1.5 litres of water-reducing plasticizer admixture) but up to around 120 litres of water per cubic metre could be used depending on the diameter of the tubes 102. This is to be compared with a semi-dry concrete mix, which typically uses less than 20 litres of water per cubic metre.
  • Concrete mix made with 70 litres of water and 1.5 litres of water-reducing plasticizer admixture typically has a slump of around 120 mm.
  • the choice of aggregate in the concrete mix is not crucial to the performance of the process, but good results have been found using an aggregate size of around 14 mm.
  • the aggregate could have a size in the range 10-20 mm.
  • the process described herein can be performed on an industrial scale even with hard aggregates such as flint. This is because the wear and tear on the mould parts is much less significant than is the case for slip-forming techniques. As a result, the process can make use of whichever aggregate is available most cheaply, most locally, or that is most suitable for the intended purpose of the moulded concrete slabs.
  • the present process can be used with aggregate having a Mohs hardness of at least 7 before abrasion the machine parts becomes a significant factor.
  • the present invention provides a much cheaper process by which hollow- core concrete slabs can be produced because the method does not require the use of augers to drive holes through a semi-dry mix or the use of diamond circular saws to cut panels from a long moulded slab of concrete - both of which must be constantly replaced at great expense even when soft aggregates are used.
  • the cutting equipment used in slip-forming factories consumes a huge volume of water for cooling and lubricating the cutting blades. This cost and wastage is also not a factor in the process of the present invention, and it also means that factories using the process of the present invention do not require the expensive cleaning equipment used in slip-forming factories to remove the waste water from the mould beds and factory floor.
  • a mesh layer 106 in the present process allows multiple hollow channels to be immediately formed in a slab as soon as the concrete has been poured and settled.
  • the mesh is not structural and does not significantly affect the physical properties of the concrete slabs.
  • the role of the mesh is to prevent the layer of concrete above the tubes from slipping as the tubes are withdrawn from the mould.
  • the tubes are shown being pulled towards end piece 202 and therefore mesh 106 is attached at least at the opposite end of the mould in order to help the upper layer of concrete moving with the tubes.
  • the mesh is fixed at end piece 201 by means of a clamp.
  • the mesh is also fixed at end piece 202 and pulled taut so as to prevent the mesh sinking when the upper layer of concrete mix is added at step 4.
  • the mesh is largely open so as to allow the concrete mix to penetrate through the mesh and ensure that the mesh does not introduce a weakness into the concrete slab.
  • the mesh has opening at least 40 mm in diameter and most preferably at least 50 mm in diameter.
  • the openings represent at least 90% of the area of the mesh, and most preferably at least 95%.
  • the mesh is pliable and flat so as to allow the mesh to roughly adopt the contours of the intermediate surface of the concrete and the tubes (107 in figure 1 ).
  • Suitable meshes include polypropylene or nylon plastic netting having a weight of less than 150 g/sq. m and preferably less than 100 g/sq. m, such as deer fencing.
  • the mesh is preferably not a metal in order to ensure that the finished concrete slab complies with modern building regulations and does not include any metal within 20 mm of the hollow channel walls.
  • mesh 106 is arranged such that filaments of the mesh are oriented transversely to the tubes 102 and extend across the mould between sides 103, 104.
  • This is illustrated in figure 2, which for clarity shows just part of the mesh layer 106.
  • the transverse filaments of the mesh are orthogonal to the axes of the tubes 102: this is preferably but not essential, and the mesh could be arranged such that the transverse filaments are at an angle to the axes of the tubes of other than 90 degrees.
  • Figure 2 also shows the mesh extending to the side of the mould: this is not essential provided that the mesh substantially covers the tubes 102.
  • layer 106 instead comprises a layer of filaments oriented across the mould transverse to the axes of the tubes 102, the filaments not being interconnected so as to form a mesh.
  • the transverse filaments are are orthogonal to the axes of the tubes 102 but the mesh could be arranged such that the transverse filaments extend between the sides of the mould at an angle to the axes of the tubes of other than 90 degrees.
  • the filaments are fixed at the sides 103 and 104 of the mould - for example, by clamping the ends of the filaments. Suitable filament materials are described above in relation to the use of a mesh.
  • the present invention allows the tubes to be withdrawn as soon as the concrete has been poured and settled.
  • a hollow-core concrete slab can therefore be formed in minutes before being left to cure.
  • equipment used in the process e.g. the concrete hopper, vibrators and tubes
  • the workers operating the equipment to start work on the next slab.
  • the process can be readily scaled up to industrial levels of production.
  • the equipment is far cheaper, and the cost of producing mould beds is much less expensive because extensive foundations are not required to support them. Hollow-core concrete factories using the process disclosed herein are therefore much cheaper to build and run.
  • the density of the tubes is chosen to be similar to the density of the concrete. This avoids the tubes sinking or floating as they are withdrawn from the mould.
  • the density of the tubes can be readily chosen by using tubes of a material that is itself more dense than the concrete mix but which are hollow such that the net density of the tubes in the mould (ignoring any parts of the tubes that do not pass through the concrete mix during withdrawal) is similar to the density of the concrete mix displaced.
  • the tubes could be hollow steel tubes whose density (of the steel plus the central hollow void it defines) is similar to that of the wet concrete mix.
  • the density of wet concrete is typically around 2400 kilos per cubic metre and hollow cylindrical steel tubing can be arranged to have a similar density through appropriate choice of wall thickness and/or the use of ballast (steel having a density of around 8000 kilos per cubic metre).
  • ballast steel having a density of around 8000 kilos per cubic metre.
  • hollow cylindrical steel tubing having an external diameter of 140 mm and a wall thickness of 6 mm can be arranged to have a net density of 2700 kilos per cubic metre through the addition of appropriate ballast. It has been found that tubes having a net density within around 15% of the density of the concrete mix can be withdrawn from the mould without the path of the tubes suffering significant deviation due to buoyancy effects. In less preferred embodiments the tubes could be solid.
  • the stiffness of the tubes 102 should be sufficient to substantially resist bending of the tubes during pouring of the concrete (when the weight of the concrete dropping onto the tubes can be significant), settling of the concrete (when the upthrust due to the settling concrete can be significant) and withdrawal of the tubes (when, as discussed above, the buoyancy of the tubes in the concrete mix can be significant).
  • the outside tubes closest to the sides of the mould are withdrawn first, followed by the central tubes 205 in any order.
  • Most preferably adjacent tubes are not withdrawn at the same time.
  • the outside tubes 1 and 8 might be withdrawn first, followed by tubes 2, 4 and 6 being withdrawn together, and then tubes 3, 5 and 7 being withdrawn together.
  • the means for withdrawing the tubes is configured to initially apply a greater force than is subsequently used to maintain the movement of the tubes out of the mould.
  • this can be arranged by attaching the tubes to a winch by means of a flexible connection (such as a chain, rope, or bungee cord) that is longer than is required to connect the pulling means to the tubes.
  • the winch is started and the slack in the flexible connections to the tubes is taken in at high speed by the winch such that when each connection becomes taut the respective tube is "yanked" from the mould.
  • a single winch can be used to pull different tubes at different moments in time.
  • the tubes are pulled from the mould but in other embodiments the tubes could be pushed from the mould - for example, by a thin rod.
  • the speed of withdrawal of the tubes is at least walking pace - typically about 4 mph. If the speed of withdrawal is substantially slower than this the tubes can drag some of the concrete mix in the direction in which the tubes are being withdrawn, resulting in a misshapen concrete slab.
  • the present process readily allows concrete slabs to be produced that have cutout portions (e.g. for soil pipes or cabling conduits) or end walls that are not orthogonal to the side walls of the mould. Such slabs are often required in the construction of modern buildings.
  • This can be achieved by inserting additional void formers into the mould to blank off portions of the mould as required by the shape that is to be produced.
  • These void formers could comprise, to give a couple of examples, metal sheets attached across the mould, or pieces of wood or polystyrene fashioned so as to define the required shape.
  • the void formers could be provided in two or more parts - one or more parts to be laid beneath the tubes and one or more parts to be laid above the tubes.
  • void formers could be provided with the appropriate holes to allow the tubes to pass through them.
  • void formers can be held in place in the mould through the use of magnets positioned in the void formers and beneath the base or on the sides of the mould.
  • fixings can be readily provided in the cured concrete slabs without requiring further processing of the slabs after curing.
  • Fixings such as sockets for rebar, lifting points and other features can be simply pushed into the wet cement mix and left to bond into the concrete as it cures.
  • slabs produced according to the present invention are spaced apart on a mould bed by at least the width of the end pieces, concrete slabs comprising tensile reinforcement can be arranged to readily provide structural connections to other slabs and building components. This can be achieved by unevenly cutting the tensile reinforcement running through two cured slabs adjacent on the mould bed such that each slab retains at least one length of tensile reinforcement projecting from the slab. For example, in the case of eight tensioned steel cables running along the mould, the steel cables can be cut between adjacent slabs such that one of the slabs retains a length of cables 1 , 3, 5, 7 and the other slab retains a length of cables 2, 4, 6, 8. The lengths of cable can be used to structurally connect each slab into the building in which it is to be used.
  • Concrete slabs produced in accordance with the present invention can be manufactured with hollow channels at least 140 mm in diameter. This is significantly larger than is possible with conventional wet mix techniques of similar speed. Furthermore, the method of production described herein does not require that the concrete slabs are provided with an upper layer of tensile reinforcement, above the level of the void-forming tubes. The method is therefore particularly suitable for making pre-stressed concrete floor panels products for which there is substantial demand in the industry.
  • factories equipped to perform the process described herein are cheaper to build and run than factories which manufacture hollow-core concrete panels using the slip-forming technique. Since the void-forming tubes can be withdrawn from the mould immediately, the technique is as fast as the predominant slip-forming method. Finally, because the process uses wet-mix concrete, the surface quality of the concrete panels formed in accordance with the method of the present invention is vastly improved over that of concrete panels formed by a slip-forming process.
  • a person skilled in the art of hollow-core concrete manufacture can readily distinguish between concrete that has been formed using a semi-dry process (e.g. from a semi-dry concrete mix, as in the case of slip-forming concrete panels) and concrete that has been formed using a wet process (e.g. from a wet concrete mix in accordance with the present process).
  • Wet-formed concrete has a significantly different internal structure in terms of the size of its internal flaws and the nature and degree of the coating of the aggregate and sand with cement.
  • dry- formed cement requires significantly more cement in the mix in order to achieve the same mechanical strength in the finished product.
  • wet-formed concrete has a significantly different surface finish (in wet-formed concrete the cement in the mix migrates to the surface to give a very high quality smooth finish).
  • the surface roughness of wet-formed concrete is significantly less than that formed from a semi-dry mix. For example, an average surface roughness of less than a millimetre is possible with wet-formed concrete, whereas the average surface roughness of concrete formed from a semi-dry mix is of the order of several millimetres (if not centimetres) due to the large number of surface imperfections.
  • the surface finish of concrete panels formed according to the present invention in particular, the lower surface formed next to the mould bed - is in fact so good that, once in situ, the panels can be simply painted and do not require a cosmetic layer of plaster or soffit.
  • hollow-core panels produced according to the present invention are reliably of higher quality, the panels can be produced to tighter tolerances and as a result lighter slabs can be engineered to support the same loads that, if produced by a slip-forming process, would require thicker and heavier slabs.
  • the tubes are hollow cylinders.
  • the tubes could be elongate void formers of any cross- section and need not be hollow.
  • the crown of the void formers (that part located uppermost in the mould) is arched since, once the void formers have been removed, this shape can support the largest diameter voids in the concrete.
  • Means for withdrawing the void formers may be any kind of machine for pulling or pushing the void formers out of the mould, including a winch system or other arrangement of motors (electric, combustion, or otherwise) a set of hydraulic or pneumatic pistons.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
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  • Architecture (AREA)
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  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
  • On-Site Construction Work That Accompanies The Preparation And Application Of Concrete (AREA)

Abstract

La présente invention se rapporte à une dalle de béton à noyau creux (101) comprenant : une pluralité de canaux creux sensiblement parallèles (300) qui s'étendent dans la dalle (101), les canaux creux (300) étant placés entre des première et seconde surfaces principales de la dalle (101) ; et une couche de filaments flexibles inertes (106) qui comporte un premier ensemble de filaments orientés transversalement par rapport aux canaux creux (300) et situés à proximité desdits canaux creux (300) entre ces canaux creux (300) et la première surface principale de la dalle (101).
PCT/EP2012/064502 2011-07-27 2012-07-24 Dalle de béton à noyau creux Ceased WO2013014157A1 (fr)

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GB1112878.2A GB2493173A (en) 2011-07-27 2011-07-27 Manufacture of hollow concrete panels
GB1112878.2 2011-07-27
GBGB1201947.7A GB201201947D0 (en) 2011-07-27 2012-02-03 Hollow-core concrete
GB1201947.7 2012-02-03

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CN109773947A (zh) * 2019-03-01 2019-05-21 中交第二航务工程勘察设计院有限公司 一种预应力筋孔成孔的夹钢丝橡胶条卷筒管及使用方法
CN111247298A (zh) * 2017-10-02 2020-06-05 李光富 现浇墙芯砌块模具框管重组盖板
CN112077981A (zh) * 2020-09-30 2020-12-15 诸暨市辉煌五金有限公司 水平相对运动气泡整理设备
RU212134U1 (ru) * 2021-07-08 2022-07-07 Федеральное государственное автономное образовательное учреждение высшего образования "Крымский федеральный университет имени В.И. Вернадского" Монолитная железобетонная балочная плита перекрытий с пустотами
CN115012571A (zh) * 2022-06-22 2022-09-06 方圆建设集团有限公司 一种装配式钢板混凝土空心楼板及其制造方法

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CN111247298A (zh) * 2017-10-02 2020-06-05 李光富 现浇墙芯砌块模具框管重组盖板
CN111247298B (zh) * 2017-10-02 2021-07-23 李光富 现浇墙芯砌块模具框管重组盖板
CN109773947A (zh) * 2019-03-01 2019-05-21 中交第二航务工程勘察设计院有限公司 一种预应力筋孔成孔的夹钢丝橡胶条卷筒管及使用方法
CN109773947B (zh) * 2019-03-01 2023-09-22 中交第二航务工程勘察设计院有限公司 一种预应力筋孔成孔的夹钢丝橡胶条卷筒管及使用方法
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CN115012571A (zh) * 2022-06-22 2022-09-06 方圆建设集团有限公司 一种装配式钢板混凝土空心楼板及其制造方法
CN115012571B (zh) * 2022-06-22 2023-07-28 方圆建设集团有限公司 一种装配式钢板混凝土空心楼板及其制造方法

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