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
  • B28B13/00—Feeding the unshaped material to moulds or apparatus for producing shaped articles; Discharging shaped articles from such moulds or apparatus
  • B28B13/02—Feeding the unshaped material to moulds or apparatus for producing shaped 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
  • B28B1/00—Producing shaped prefabricated articles from the material
  • B28B1/008—Producing shaped prefabricated articles from the material made from two or more materials having different characteristics or properties
• • 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
  • B28B1/00—Producing shaped prefabricated articles from the material
  • B28B1/08—Producing shaped prefabricated articles from the material by vibrating or jolting
  • B28B1/084—Producing shaped prefabricated articles from the material by vibrating or jolting the vibrating moulds or cores being moved horizontally for making strands of moulded 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
  • B28B13/00—Feeding the unshaped material to moulds or apparatus for producing shaped articles; Discharging shaped articles from such moulds or apparatus
  • B28B13/02—Feeding the unshaped material to moulds or apparatus for producing shaped articles
  • B28B13/0215—Feeding the moulding material in measured quantities from a container or silo
  • B28B13/022—Feeding several successive layers, optionally of different materials
• • 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
  • B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
  • B28B3/20—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded
  • B28B3/22—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded by screw or worm
  • B28B3/228—Slipform casting extruder, e.g. self-propelled extruder
• • 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

• the invention relates to a method according to the preamble of claim 1 for manufacturing a concrete product by means of an extrusion technique.
• the invention also relates to an extruder-type casting apparatus suited for implementing the method according to the invention.
• Cast concrete products such as hollow-core slabs, piles or solid-core slabs can be made using an extruder-type casting technique.
• Hollow-core slabs or the like load- bearing structures subjected to tensile stresses are reinforced by longitudinal reinforcing steel bars or prestressing steel wire strands.
• the use of crosswise placed steel inserts as well as other reinforcing steels in the form of conventional inserts or wire mesh is so complicated to arrange in mass production that the use of such reinforcement steel fabrics is not possible due to technical and economical restraints.
• slabs find limited applications within the regulations of normal building codes and as to their static and dynamic load-bearing capability and resistance under fire situa- tions. These limitations are accentuated in broad slabs, at the edges of large openings and when the slab is subjected to large point or lineal loads. The same limitations are partially true for products manufactured using other slip-casting methods, too.
• the element may be cast from a concrete mix having reinforcing fiber such as steel fiber added thereto for the purpose of allowing the building component such as a hollow-core slab to be used under normal code regulations with due attention paid to the function of the building component under static and dynamic loads and in fire situations.
• reinforcing fiber such as steel fiber added thereto
• the building component such as a hollow-core slab
• steel fiber is easy to add into the concrete mix used and such fiber is the most preferred choice by its function and cost.
• the goal of the invention is achieved by means of distri- buting the fiber reinforcement in an inhomogeneous fashion within the volume of the product so that at least one portion of the product volume has a greater volumetric content of the reinforcement than that of an equivalent volume in at least one other portion of the product .
• At least two feeder containers are used in the manufacture of the concrete product.
• one container is filled with a normal concrete mix and the other with fiber-reinforced concrete mix.
• the feed ratio of these two mixes it is possible to control the fiber density in the different portions of the component being manufactured.
• the fiber-containing mix may be extruded via the auger into different portions of the cast product so that the fiber content of each portion reaches a desired level.
• the method according to the invention is characterized by what is stated in the characterizing part of claim 1.
• the invention provides significant benefits.
• the fiber reinforcement can be dosed in desired amounts into a desired portion of a component, thus placing the reinforcement in the most appropriate locations.
• the addition of fiber reinforcement can be employed to increase, e.g., the spectrum of applications, competitive edge and technical performance of prestressed hollow-core slabs.
• a lesser quantity of fiber reinforcement will be sufficient to produce a building component having the same strength as that possessed by prior-art products.
• the structure of the manufactured components may also be lightweighted, thus expanding the range of their applica- tions.
• the static and dynamic load-bearing capability of hollow-core slabs made using the method according to the invention is improved, which means that among others such qualities as their loading capacity and resistance under vibration and movement is improved thus rendering them a superior performance under seismic conditions.
• the slabs may also be subjected to larger lateral loads.
• the fiber reinforcement reduces cracking of the slabs and improves their shear strength. Additional fiber reinforcement at the lateral sides of the slabs increases their strength under lifting and tor- sional loads.
• the reinforcement When applied at the edges of slab openings, the reinforcement improves the overall load-bearing capability of slabs, while addition of fiber reinforcement to the isthmuses remaining between the hollow spaces of the slab core can give the slab a higher shear strength and reinforcement at the bottom of the slab reduces cracking of slabs. Respectively, addition of reinforcement to the top wall of large hollow spaces in the slab helps keep the cast product in shape during casting.
• Ram piles manufactured using the method according to the invention can be reinforced at their top ends resistant to the blows of the ram. When necessary, slabs or other similar products may be manufactured even in singular quantities with individually placed reinforcements according to the loading situation in the target application. By virtue of the invention, it is possible to use different types of dimensioning rules and structural designs, since there is no more any need for designing the entire slab according to the peak load occurring within a limited area.
• FIG. 1 shows a side view of an embodiment of an apparatus according to the invention suited for the manufacture of three concrete piles
• FIG. 2 shows a front view of the apparatus illustrated in FIG. 1;
• FIG. 3 shows a cross-sectional view of a hollow-core slab manufactured according to the invention
• FIG. 4 shows a perspective view combined with a cross- sectional view of another embodiment of a hollow-core slab manufactured according to the invention.
• FIG. 5 shows a cross-sectional view of a third embodiment of a hollow-core slab manufactured according to the invention.
• the apparatus comprises a metallic framework 7 having adapted thereto a conical hopper container 8 in which the top and the bottom are open.
• a partition 12 divides the hopper con- tainer 8 in two compartments, named a basic mix container
• the feeder means 4 comprises a wide toothed gear 9, a drive shaft 10 of the toothed gear adapted to penetrate the container wall and a drive motor not shown in the diagram serving to rotate the drive shaft 10 from the exterior side of the container.
• a control vane 3 To the lower edge of the partition 12 is hingedly mounted a control vane 3 by means of which the cross-sectional ratio between the bottom openings of the hopper container compartments can be adjusted.
• the size of the control vane 3 is dimensioned so that if necessary the vane 3 can entirely shut off the exit openings at the bottom corner of either one of the container compartments 1, 2 so that the angle of the control vane 3 relative to a vertical plumb line does not exceed a given angle (e.g., an angle not greater than 40°), thus avoiding the hinges of the vane from becoming subjected to an excessive stress under the weight of the overlying concrete mix.
• a tube 19 is adapted to the lower part of the container, under the control vane 3. The lower portion of the tube 19 is aligned to fit into an opening made to the framework 7.
• Three auger feeders 5 with their infeed ends coinciding with the overlying outlet end of the tube are mounted in a horizontal position to the interior of the framework.
• the framework 7 has solid walls at its both sides facing the auger feeders.
• Each auger feeder 5 with its one supported by the framework 7 and the other end terminating at a core- forming member 6 is rotatably mounted on bearings.
• the wall of the framework 7 on which the augers are mounted on bearings is provided with openings via which reinforcing bars can be introduced into the cast mix.
• Below the auger feeders 5 are mounted the concrete mix feed troughs 24 that pass the concrete mix further toward the extruder section .
• the extruder section of this type of apparatus operates in the same fashion as a conventional extruder-type casting apparatus, wherein the auger feeders 5 extrude the concrete mix through the extruder section which is defined from above by a top wall 20 of the casting apparatus framework and, in the cross-machine direction, by side and intermediate walls 21 that serve to laterally compartmentalize the extruder section and, finally, by the core- forming members 6.
• the concrete mix is compacted and worked in the extruder section interior space 20, 21, 6 under the pressure exerted by the auger feeders 5 and the movement of a compacting device 22 mounted on the top wall 20.
• the auger feeders 5 are arranged to propel concrete mix into the spaces formed between the core-forming members 6 and the walls 20, 21 of the extruder section.
• the extruder section is defined so that the concrete mix propelled therethrough is forced to form three objects of a square external cross section and a cylindrical hollow core defined by the core-forming member 6.
• the undercarriage portion of the framework 7 is provided with axles 13 and 14, each one of them having two wheels mounted thereon so that the axle 13 is running on wheels 15 and 16, while the axle 14 is running on wheels 17 and 18, respectively. Supported on the wheels, the entire apparatus moves on the casting bed under the propelling force exerted by the auger feeders.
• the apparatus shown in FIG. 1 is suited for the manufacture of ram piles by virtue of the method described below.
• a basic concrete mix and a batch of steel fiber are prepared.
• the reinforcing steel fiber is mixed with a portion of the prepared concrete mix.
• the unreinforced portion of the mix called gray concrete is poured into the basic mix container 1, while the fiber- reinforced portion is filled into the reinforcement material container 2.
• the feeder means 4 is rotated to ensure unproblematic feed of the stiff fiber- reinforced portion from the reinforcement material container 2 forward into the extruder section.
• the ratio of the cross-sectional area of the bottom openings of the basic mix container 1 and the reinforcement material container 2 is controlled by adjusting the position of the control vane 3.
• the surface area ratio between the bottom openings of the container compartments determines the feed ratio between the different concrete mixes passing from both sides of the control vane and, hence, the amount of fiber reinforcement, as a function of the length or casting time of products being cast, in the blended mix passing forward in the system.
• the feed ratio of the different materials being cast can be selected to be controlled by a function related to the time or instantaneous position of the casting apparatus travel .
• the blended concrete mix is poured along a cylindrical tube 19 through an opening of a horizontal cross section into the space surrounding the auger feeders 5, wherefrom the auger feeders propel the mix through the extruder section.
• the above-described apparatus is suited for the manufacture of such products in which the proportion of the reinforced concrete mix is varied in the longitudinal or vertical direction of the finished product.
• the auger feeders do not actually agitate the concrete mix, but rather, propel it forward, a proportionally greater amount of the unreinforced gray concrete being fed to the rear of the auger feeders travels guided by the auger feed trough 24 to the space of the extruder section underlying the augers.
• the angular position of the control vane 3 determines the proportion of reinforced material in the mix being fed and the entry point of the same on the augers 5.
• the slab illustrated in FIG. 4 with the reinforced concrete placed zone-wise over the length of the slab is suited for use in applications in which a limited area is stressed by a load such as a lineal load acting in a defined manner.
• This category includes such applications as, e.g., structures designed to support a load-bearing wall or constructions placed under conveyors or tracks.
• the reinforcement is concentrated at the lateral sides of the slab, thus rendering the side areas a good compressive load resistance and shear strength.
• the illustrated slab is also strengthened by cross-wise placed reinforcement steels.
• their reinforcement addition techniques serve as starting points for the combinations thereof.
• FIG. 6 an apparatus suited for improved distribution of the concrete mixes to the different portions of the slab in its vertical direction.
• the discharge tube of the concrete mix feed hopper 8 is provided with a movable baffle 30 having its lower edge extending close to the upper level of the augers 5.
• this baffle it is easy to control the discharge point of the fiber-reinforced concrete mix into the auger feed trough 24 and, hence, in the vertical direction of the cross section of the cast product. If the lower edge of the baffle 30 is rotated close to the start of the auger flight, the reinforced concrete is effectively guided by the feed trough to the bottom portion of the cast product.
• both container compartments are equipped with separate closing means 31, 32 in order to provide independent feed rate control for either type of concrete mix.
• the apparatus according to the invention can be provided with feed nozzles of the fiber-reinforced concrete mix that are located at different points in the longitudinal, lateral and height directions of the feed nozzle area.
• the concrete mix can be forced through the nozzles with the help of auger feeders or pumps.
• the reinforcing fibers are mixed in substantial quantities in a bonding agent such as slurried cement, and the feed rate of the reinforcing material through the nozzles can be controlled by manual or electronic means as a function of casting time on the basis of product data retrieved from a database.
• the rotation speed of the augers is made adjustable as a function of casting time.
• control vane 3 is divided into at least two separately hinged parts, whereby the content of fiber reinforcement in the product being cast can be adjusted in both the longitudinal and lateral direction of the product.
• the concrete mix feed is arranged to take place from a system such as a container or a concrete mixing machinery separate from the extruder apparatus via piping to the extruder appa- ratus .
• a disadvantage of this arrangement is, however, that at the end of a run there will remain a large amount of concrete in the piping, particularly on production lines adapted for the manufacture of long products.
• the closing devices adapted to the separate compartments and concrete mix feeder means may obviously be of any other type, e.g., sliding gates or expandable closing bellows made from a flexible material.
• the concrete mix feed tube 19 connected to the containers may be designed into a changeable nozzle tube assembly having passageways or channels for concrete feed into a desired point in a longitudinal or lateral direction along the product being cast.
• This kind of a nozzle assembly could be provided with a number of separate concrete feed lines passed from the hopper container to the discharge opening located above the auger feeders.
• the apparatus can be adapted more readily for the manufacture of different kinds of products.
• the invention also makes it possible to design apparatuses equipped with core- forming members of varied shapes that permit the manufacture of lightweight structures having respectively varied hollow-core shapes.
• the method according to the invention is also suited for the manufacture of such products that are made using a greater number of different concrete mixes than the above-mentioned fiber-reinforced concrete mix and the unreinforced gray concrete mix conventionally used in standard products.
• the reinforcing material may be selected from the group of other suitable materials such as synthetic fiber, glass fiber and metallic fiber of a non-steel variety.
• the advantageous price, good strength and the thermal expansion coefficient matching that of concrete, however, give steel fiber a preference as the most cost-efficient reinforcement material.
• the fiber reinforcement may be blended in the basic concrete mix among other additives such as slurried cement.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
• Press-Shaping Or Shaping Using Conveyers (AREA)
• Producing Shaped Articles From Materials (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1999
  • 1999-05-21 FI FI991165A patent/FI109982B/fi not_active IP Right Cessation
• 2000
  • 2000-05-19 AU AU47592/00A patent/AU4759200A/en not_active Abandoned
  • 2000-05-19 DE DE60009901T patent/DE60009901T2/de not_active Expired - Lifetime
  • 2000-05-19 EP EP00929569A patent/EP1187709B1/de not_active Expired - Lifetime
  • 2000-05-19 WO PCT/FI2000/000458 patent/WO2000071315A1/en active IP Right Grant

Non-Patent Citations (1)

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