JP3909081B1 - Method for producing concrete structure and formwork structure - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a concrete structure having a hollow portion, which can be applied without difficulty even when the hollow portion is large-scale.
A method of manufacturing a concrete structure having a hollow portion, in which an inner mold frame 10 formed by forming a weir plate layer 10B made of a bead-method foamed plastic on the outer surface of a supporting structure 10A becomes a hollow portion. After the arrangement, the fresh concrete is placed around the inner mold 10 and the volume of the dam plate layer 10B is reduced after the concrete reaches the demolding strength.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a concrete structure and a formwork structure.

  When manufacturing a concrete structure with a space inside or a concrete structure with a box opening, the internal space or box opening is formed inside the outer mold to form the outer surface of the concrete structure. It is common to use a formwork structure in which an inner formwork (including a boxed formwork) is arranged. In the following, the internal space and the box opening part of the concrete structure are referred to as “hollow part”.

  In recent years, when an inner mold is constructed using steel or wooden dams, it is difficult to install or remove the mold. In recent years, an inner mold made of solid beaded foam plastic (foamed polystyrene) is used. A method for producing a concrete structure using a slab has been developed (see, for example, Patent Documents 1 to 4).

  In the method for manufacturing a concrete structure disclosed in Patent Document 1 and Patent Document 2, a plurality of solid foamed polystyrene blocks are stacked to form an inner mold, and fresh concrete is placed around the block. A concrete structure having a hollow portion is constructed by removing the inner mold after the concrete has reached demolding strength. According to such a method for manufacturing a concrete structure, the installation work and the demolding work are facilitated as much as the inner mold is lighter.

  Even in the method for manufacturing a concrete structure disclosed in Patent Document 3 and Patent Document 4, a solid foamed plastic is used as an inner mold frame, and after the concrete has reached demolding strength, the inner mold frame is removed, so that the hollow portion However, when the inner mold is removed, the foamed plastic as the inner mold is dissolved by a solvent or melted by heating. According to such a method for manufacturing a concrete structure, even when the inner space of the hollow portion is widened or when the concrete is firmly attached to the inner mold, the inner mold can be easily removed. It can be removed.

  Patent Document 3 discloses a case where an inner mold frame made of solid expanded polystyrene is dissolved with xylene or gasoline and an inner mold frame made of solid foamed polyethylene or beeswax is heated to melt or This is an example of softening deformation. Patent Document 4 discloses an example in which an inner mold made of solid foamed polystyrene is dissolved with a ketone solvent.

Japanese Patent Laid-Open No. 6-137084 JP 2000-064314 A Japanese Patent Publication No. 6-072490 Japanese Patent Application Laid-Open No. 8-060781

  Since a large restraining force acts on the inner mold as the concrete shrinks and shrinks, in the concrete structure manufacturing methods of Patent Document 1 and Patent Document 2 that do not reduce the volume of the inner mold, the inner mold is easily formed. There is a problem that it cannot be removed.

  According to the inventions disclosed in Patent Document 3 and Patent Document 4, the above-mentioned problems can be solved theoretically, but this invention is a small-scale hollow for fixing the end of PC steel. This is not suitable for concrete structures having large hollow portions such as box girders and box culverts of road bridges. That is, in the method for manufacturing a concrete structure according to Patent Document 3 and Patent Document 4 in which a solid foamed plastic lump needs to be disposed in a portion that becomes a hollow portion, when the hollow portion becomes large, it is disposed in the hollow portion. As the volume of foamed plastic becomes enormous, the amount of solvent and heat required to reduce the volume of foamed plastic becomes enormous, and the time it takes for the solvent and heat to reach the center of the foamed plastic is also long. turn into.

  In addition, when the inner mold is used, buoyancy acts on the inner mold when fresh concrete is placed. However, the methods for producing concrete structures disclosed in Patent Documents 3 and 4 are large-scale. When applied to a concrete structure having a hollow portion, a large bending moment and shearing force are generated in the inner mold due to buoyancy, and harmful deformation may occur in the inner mold. If harmful deformation occurs in the inner mold, the dimensional accuracy of the concrete structure is naturally deteriorated. Further, in the concrete structure manufacturing methods of Patent Document 3 and Patent Document 4, since the entire inner mold is made of foamed plastic with low rigidity, an overload is applied when setting the inner mold. There is a problem that construction efficiency cannot be improved.

  From such a point of view, the present invention provides a method for manufacturing a concrete structure having a hollow portion, which can be applied without difficulty even when the hollow portion is large-scale. It is another object of the present invention to provide a formwork structure suitable for use in the method for manufacturing a concrete structure.

The present invention for solving such problems is a method for producing a concrete structure having a hollow portion, and an inner mold formed by forming a bead plate foam plastic weir plate layer on the outer surface of a support structure, After placing at the position to be the hollow portion, placing fresh concrete around the inner mold frame, and heating the barrier plate layer to 70 to 100 ° C. after the concrete has reached demolding strength. in, characterized in that for volume reduction the volume of the sheathing board layer.

  The hollow portion is a general term for a space formed inside a concrete structure or a box opening (concave portion) formed on the surface of the concrete structure. The hollow portion may have a closed cross section or an open cross section.

The present invention is characterized in that an inner mold frame formed by forming a weir plate layer made of a bead method foamed plastic on the outer surface of the support structure is used. The inner mold can be removed by reducing the volume of at least the weir plate layer of the inner mold, so a concrete structure having a large hollow part such as a box girder or box culvert of a road bridge. Even in the case of manufacturing, it is possible to reduce the amount of the beaded foam plastic used compared to the case where the entire inner mold is made of the beaded foam plastic. That is, according to the present invention, all of the inner mold as compared with the case of the bead method foamed plastic, it is possible to reduce the heat amount for causing the volume reduction of the beads method foamed plastic, further foam by beads method It is also possible to shorten the time until the heat reaches the center of the plastic. In other words, even if the hollow part of a concrete structure is large-scale, the manufacturing method according to the present invention can be applied without difficulty. Further, according to the present invention, a gap is formed between the concrete structure and the inner mold even if a large restraining force is applied to the inner mold as the concrete shrinks and shrinks. The frame can be easily removed.

To volume reduction the volume of the sheathing board layer, it is sufficient before Symbol heating the sheathing board layer is shrinkage. In particular, when the bead method foamed plastic is bead method foam polystyrene, the volume of the dam plate layer may be reduced by heating and shrinking the dam plate layer. For example, in the case where an inner mold is formed using foamed polyethylene, even if the foamed polyethylene is heated to be melted or softened and deformed, it is cured again when it returns to room temperature. If the state is not maintained, it may be difficult to remove the inner mold, but if the inner mold is constructed using beaded polystyrene foam, it will be permanent after returning to normal temperature. Since it is contracted, it is not necessary to maintain a high temperature state during demolding. The heating temperature when the dam plate layer is made of beaded expanded polystyrene may be set as appropriate within a range in which the dam plate layer can be shrunk. As a result, the gap between the concrete structure and the inner mold is reduced. Therefore, it is preferable to heat the barrier plate layer to 70 ° C. or higher, and more preferably to 80 ° C. or higher. It is desirable. In addition, if the heating temperature is increased more than necessary, the structure of the hydrated product in the concrete becomes rough, and the long-term durability performance may be lowered. Therefore, the heating temperature of the dam plate layer is 100 ° C. or less. Is desirable.

  In the case where heat curing and steam curing are performed after placing concrete, the weir plate layer may be heated using the heat of the heat curing or the heat of steam curing. If it does in this way, it will become possible to remove the inner mold form quickly at the time when heat curing and steam curing are completed while improving the strength of concrete at an early stage. In addition, steam curing may be performed under normal pressure (under atmospheric pressure), or may be performed under a pressure higher than normal pressure.

The type of concrete used in the method for producing a concrete structure according to the present invention is not particularly limited, and includes, for example, cement, a pozzolanic reaction particle, and an aggregate having a maximum particle size of 2.5 mm or less. 1 to 4% by volume of fibers having a diameter of 0.1 to 0.3 mm and a length of 10 to 30 mm are mixed in a cement-based matrix obtained by mixing a powder with a high-performance water reducing agent and water. If the resulting concrete is used, it is possible to obtain a concrete structure having a high elastic modulus (for example, E = about 50 to 55 kN / mm ² ) and high resistance to tensile force. In addition, since such a concrete tends to increase the amount of self-shrinkage, if a steel plate or a wooden plate material having a large rigidity is used as a dam plate for the inner mold, the shrinkage of the concrete is restrained and remains inside. Although the tensile stress increases, in the present invention, the barrier layer corresponding to the barrier plate is formed of a beaded foamed plastic having a rigidity lower than that of a steel or wooden barrier plate. It is not restrained more than necessary, so that the tensile stress remaining in the concrete after hardening can be reduced.

As a formwork structure used when manufacturing a concrete structure having a hollow part, an inner formwork for forming the hollow part, an outer formwork for forming an outer surface of the concrete structure, A mold structure comprising a spacer for maintaining a distance between the inner mold frame and the outer mold frame , wherein the inner mold frame is a support structure and a bead method foaming formed on an outer surface of the support structure. possess a plastic sheathing board layer, said barrier plate layer and the outer frame, respectively, to the position where the spacer is disposed, through holes are formed, the spacer, the barrier plate It is desirable to form a communication hole that connects the through hole of the layer and the through hole of the outer mold .

  According to this formwork structure, it is possible to easily reduce the volume of at least the dam plate layer of the inner formwork. Even when the inner mold is firmly attached, the inner mold can be easily removed. Further, in this formwork structure, it is only necessary to reduce the volume of at least the dam plate layer of the inner formwork, so that the bead method foaming is performed as compared with the case where the entire inner formwork is made of beaded foam plastic. It is possible to reduce the amount of solvent and heat for reducing the volume of plastic.

  Although there is no restriction | limiting in particular in the structural type of the said support structure, If it contains the frame structure which combines a rod-shaped element, it will become possible to achieve weight reduction of an inner mold. In addition, when the said support structure is comprised including the frame structure, it is good to interpose a plate-shaped member between the said dam plate layer and the said frame structure. If it does in this way, since it becomes possible to support a dam plate layer surface, it becomes possible to suppress a deformation | transformation etc. of a dam plate layer.

  There are no particular restrictions on the material of the support structure, and steel, aluminum alloy, wood, and plastic can be used, but if it is made of polystyrene resin, it is transformed into a gel with a Nootkaton volume reduction solution. Therefore, the inner mold can be removed more easily.

In mold structure according to the present invention, the pre-Symbol outer frame for forming an outer surface of the concrete structure, since the and a spacer for holding a distance between the inner formwork and the outer formwork , even when the lateral pressure such as the inner mold and outer mold and Da設fresh concrete is applied, it is possible to maintain the positional relationship between the inner mold and outer mold constant and Do Ri , it is possible to obtain a high dimensional accuracy concrete structure.

In the mold structure according to the present invention, a through hole is formed in the barrier plate layer and the outer mold frame at a position where the spacer is disposed, and the through hole of the barrier plate layer and the outer mold frame are formed in the spacer. Therefore , it is possible to supply a solvent and heat for reducing the volume of the barrier plate layer by using the insertion hole of the spacer.

  In the case where a female screw is formed in the support structure at a position corresponding to the through hole of the barrier plate layer, the through hole of the outer frame, the communication hole of the spacer, and the through hole of the barrier plate layer It is preferable to fix the inner mold frame and the outer mold frame by screwing a male screw inserted into the female screw into the female screw. In this way, even when buoyancy or lateral pressure is applied to the inner formwork due to the placement of fresh concrete, it becomes possible to prevent the inner formwork from lifting, and thus to obtain a concrete structure with high dimensional accuracy. Is possible.

  In the formwork structure according to the present invention, the dam plate layer may be formed by abutting a plurality of bead method foamed plastic dam members. In this way, when heat or a solvent is supplied to the barrier layer, each barrier member is contracted and a gap is formed between adjacent barrier members. Since the gap functions as a heat or solvent supply path, the time required to melt or shrink the barrier layer can be further reduced.

  When a dam plate layer is composed of a plurality of dam plate components, the boundary portion between the adjacent dam plate components may be sealed. If it does in this way, since it becomes possible to prevent the invasion of the concrete from the boundary part of an adjacent dam board component material, it becomes possible to obtain a high-quality concrete structure.

The method for producing a concrete structure according to the present invention can be applied without difficulty to a concrete structure having a large-scale hollow portion. That is, according to the method for producing a concrete structure according to the present invention, since the inner mold formed by forming a bead foam plastic weir plate layer on the outer surface of the support structure is used, the entire inner mold the as compared with the case where a bead method foamed plastic, it is possible to reduce the amount of expensive beads method foamed plastic, further, it can reduce the heat quantity to be reduced in volume the beads method foamed plastic It becomes.

  Further, according to the formwork structure according to the present invention, since the weir plate layer made of the bead method foamed plastic is formed on the outer surface of the support structure, when the entire inner formwork is made of the bead method foamed plastic, In comparison, it is possible to reduce the amount of expensive bead-method foamed plastic used, and it is also possible to reduce the amount of solvent and heat for reducing the volume of the bead-method foam plastic.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out a concrete structure manufacturing method and a formwork structure according to the present invention will be described in detail with reference to the accompanying drawings. In the following embodiment, as shown in FIG. 7, a case where the concrete structure C to be manufactured is a box girder of a road bridge is exemplified. However, the method and method for manufacturing a concrete structure according to the present invention It is not intended to limit the scope of the structure.

First, the formwork structure 1 according to the present embodiment will be described in detail with reference to FIGS.
The formwork structure 1 shown in FIG. 1 is used when manufacturing a concrete structure C (see FIG. 7), and includes an inner formwork 10, an outer formwork 20, spacers 30, 30,. , And bolts 40, 40,... That are fixing means. In addition, in the concrete structure C shown in FIG. 7, the hollow part V of a closed cross section is formed in the inside.

  The inner mold 10 shown in FIG. 1 is for forming the hollow portion V (see FIG. 7), and includes a support structure 10A and a dam plate layer 10B.

  The support structure 10A supports the dam plate layer 10B, and has a rigidity that does not cause harmful deformation in the dam plate layer 10B due to the weight, lift pressure, side pressure, and the like of the placed concrete. That is, the rigidity of the support structure 10A is higher than that of the barrier plate layer 10B. As shown in FIG. 2A, the supporting structure 10A includes a plurality of (three in the present embodiment) frame structures 11, 11, 11 arranged in parallel at a predetermined interval, and a frame structure. The plate-shaped members 12, 12,... Arranged so as to surround the 11, 11, 11 are configured.

  The frame structure 11 includes rod-shaped elements 11a, 11a,... Combined in a lattice shape, and nuts 11b, 11b fixed to appropriate positions of the rod-shaped element 11a. As shown in FIG. 3, the rod-like element 11a is formed with through holes 11c, 11c,. There are no particular restrictions on the material and cross-sectional shape of the rod-shaped element 11a, but it is easy to procure materials such as grooved steel, H-shaped steel, angle steel, rectangular steel pipe, extruded shape made of aluminum alloy, wood, and plastic rod. It may be composed of materials. The rod-shaped elements 11a, 11a,... May be combined so as not to be disassembled by means such as welding or adhesion, or may be combined such that they can be disassembled using bolts or the like. The nut 11b is fixed to a position corresponding to the through hole 11c by welding or adhesion.

  As shown in FIG. 2, the plate-like member 12 constitutes the outer shell of the support structure 10 </ b> A, and is fixed to the outer peripheral surface of the frame structure 11. As shown in FIG. 3, the plate-like member 12 has a through hole 12 a at a position corresponding to the through hole 11 c of the frame structure 11. The material of the plate-like member 12 is not particularly limited, but may be made of a material that can be easily procured such as steel, aluminum alloy, wood, and plastic. The plate-like member 12 may be assembled to the frame structure 11 so as not to be disassembled by means such as welding or adhesion, or may be assembled so as to be disassembled with a bolt or the like.

  The dam plate layer 10B shown in FIG. 1 forms the inner surface (surface surrounding the hollow portion V) of the concrete structure C (see FIG. 7). It is comprised by the material 13,13, ....

  The weir plate component 13 is made of beaded foamed polystyrene (also called expanded polystyrene (EPS)), which is a kind of beaded foamed plastic. As shown in FIG. It is fixed to the plate-like member 12 of the structure 10A. A through hole 13 a is formed in the dam member 13 at a position where the spacer 30 is disposed. In this embodiment, the barrier plate component 13 has a plate shape. However, the shape of the barrier plate component material 13 is not limited to the shape of the barrier plate member 13 and may be a block shape depending on the shape of the hollow portion V (see FIG. 7). is there.

  The boundary portion between the adjacent weir plate members 13, 13 is covered with a film-like member 13b made of a synthetic resin such as polyethylene. That is, the boundary portion between the barrier plate members 13 and 13 is sealed by the membrane member 13b. A sealing material may be used instead of the film member 13b or in combination with the film member 14b. That is, the boundary portion between the barrier plate constituent materials 13 and 13 may be sealed by interposing a sealing material between the barrier plate constituent materials 13 and 13. Moreover, you may seal a boundary part by adhere | attaching the abutting surfaces of the adjacent dam board constituent materials 13 and 13 with an adhesive agent, or welding.

There is no particular limitation on the expansion ratio of the bead-method expanded polystyrene constituting the dam plate component 13, but if it is less than 20 times, the volume shrinkage due to heat or solvent becomes small, so 20 times or more (that is, 1 m It is desirable that the mass per ³ is 50 kg or less), and considering that the larger the volume shrinkage is, the easier it is to remove the mold, it is more desirable that the mass is 40 times or more (the mass per 1 m ³ is 25 kg or less). . Further, if the expansion ratio exceeds 60 times, the deformation due to the weight of the concrete and the side pressure increases, so it is desirable that the expansion ratio is 60 times or less (the mass per 1 m ³ is 16 kg or more).

  In addition, the manufacturing method of bead method expanded polystyrene is not specifically limited, What is necessary is just to select an appropriate thing from conventionally known manufacturing methods, such as a bead fusion molding method.

  The beaded polystyrene foam melts or shrinks when heated. For example, when bead-method expanded polystyrene is heated at a temperature of 70 to 100 ° C. for about 48 hours, the contraction rate of length (that is, the ratio of the contraction length contracted by heating to the length before heating) is about 20 to 40%. become. A bead-method expanded polystyrene having an expansion ratio of 40 times, 50 times, and 60 times was placed in a thermostatic chamber at 95 ° C., and the change in shrinkage with time was investigated. FIG. 4 is a graph showing the relationship between the contraction rate of length and the elapsed time. As can be seen from this graph, when the bead-method expanded polystyrene is heated in an environment of 95 ° C. for 50 hours, the shrinkage ratio of length becomes 32 to 44% (68.6 to 82.4% in terms of volume shrinkage ratio). I understand that In addition, the bead method expanded polystyrene melts when heated to 270 ° C. or higher.

  Further, the beaded polystyrene foam is dissolved (melted) by the limonene solution. Limonene can be extracted from orange peel, for example. In addition, since the polystyrene melt | dissolved with the limonene solution is not necessarily decomposed | disassembled, it can isolate | separate from limonene easily.

  In addition, the volume of the beaded polystyrene is reduced by the Nootkaton volume reduction solution. The Nootkaton volume-reducing liquid can be obtained, for example, by mixing citrus oil extracted from grapefruit peel and ethyl alcohol or isoparaffin. When the Nootkaton volume-reducing liquid is supplied to the bead method expanded polystyrene, the air in the bead method expand polystyrene is released, the volume of the polystyrene shrinks, and changes into a gel-like object.

  The outer mold frame 20 shown in FIG. 1 is for forming the outer surface of the concrete structure C (see FIG. 7), and includes a dam plate and the like. In the present embodiment, the outer mold frame 20 includes a bottom plate portion 21 and side plate portions 22 and 22 erected on the bottom plate portion 21. As shown in FIG. 3, a through hole 21 a is formed in the bottom plate portion 21 at a position where the spacer 30 is disposed. In addition, although illustration is abbreviate | omitted, the through-hole is formed also in the side plate part 22 in the position where the spacer 30 is arrange | positioned. The material of the outer mold 20 is not particularly limited, and various materials such as steel, stainless steel, aluminum alloy, wood, and plastic can be used.

  The spacer 30 is for maintaining a space between the inner mold 10 and the outer mold 20, and in this embodiment, includes a spacer body 31 that has a cylindrical shape and a support member 32 that has a ring shape. Configured.

  The material of the spacer body 31 is not particularly limited, and various materials such as steel, stainless steel, aluminum alloy, and plastic (vinyl chloride, polyethylene, acrylic) can be used. Moreover, the form of the spacer 31 is not limited to the illustrated one, and may be changed as appropriate. For example, in the present embodiment, the spacer 31 having a cylindrical shape is illustrated, but the present invention is not limited to this, and may be a polygonal cylindrical shape.

  The bearing member 32 is interposed between the barrier plate layer 10 </ b> B (the barrier plate constituent material 13) and the spacer body 31. In the support member 32, the area of the surface (contact surface) that contacts the barrier plate layer 10B is larger than the area of the end surface of the spacer body 31 on the side of the barrier plate layer 10B, and the support member 32 acts on the barrier plate layer 10B. The local stress of the barrier plate layer 10B is suppressed by relaxing the pressure stress. In addition, there is no restriction | limiting in particular in the material of the bearing member 32, Various materials, such as steel, stainless steel, an aluminum alloy, and plastics (vinyl chloride, polyethylene, acrylic), can be used.

  In the spacer main body 31 and the pressure supporting member 32, communication holes 31a and 32a are formed, respectively. The through holes 13a of the barrier plate layer 10B and the through holes 21a of the outer mold frame 20 communicate with each other through the communication holes 31a and 32a.

  The bolt 40 is for connecting and fixing the inner mold 10 and the outer mold 20, and a male screw 41 is formed on the shaft portion thereof. The shaft portion of the bolt 40 is inserted into the through hole 21a of the outer mold 20, the communication holes 31a and 32a of the spacer 30, the through hole 13a of the barrier plate layer 10B and the through holes 11c and 12a of the support structure 10, and the male screw 41. Is screwed into a female screw formed on the nut 11 b of the frame structure 11.

Next, a method for manufacturing a concrete structure according to this embodiment will be described in detail. The mixing of the concrete to be placed is not particularly limited, but in this embodiment, a high-performance water reducing agent is added to the powder containing cement, a pozzolanic reaction particle, and an aggregate having a maximum particle size of 2.5 mm or less. Concrete (fiber reinforced concrete) in which 1 to 4% by volume of fibers having a shape of 0.1 to 0.3 mm in diameter and 10 to 30 mm in length are mixed into a cement matrix obtained by mixing water Is used. Here, the pozzolanic reaction particles are particles made of, for example, silica fume, fly ash, blast furnace slag, a compound selected from kaolin derivatives, precipitated silica, volcanic ash, silica sol, and the like. Incidentally, such a concrete cured body has a compressive strength in the range of 150 to 200 N / mm ² , a bending tensile strength in the range of 25 to 45 N / mm ² , and a split tensile strength of 10 to 10. It is in the range of 25 N / mm ² .

  In the concrete structure manufacturing method according to the present embodiment, the inner mold frame 10 formed by forming the weir plate layer 12 made of the bead method foamed plastic on the outer surface of the support structure 11 is formed with the hollow portion V (see FIG. 7). (See FIG. 5C), a fresh concrete C ′ is placed around the inner mold 10 (see FIG. 6A), and the concrete C ′ has a demolding strength. After reaching, the volume of the dam plate layer 10B is reduced (see FIG. 6C). In the following description, assuming that the concrete is fiber reinforced concrete, a form installation process, a placing process, a primary curing process, an outer mold removal process, a secondary curing process, A method for producing a concrete structure including an inner mold release step is illustrated.

(Formwork installation process)
As shown in FIGS. 5A to 5C, the mold installation process is a process of installing the inner mold 10 and the outer mold 20 at predetermined positions.

  In the mold installation step, as shown in FIG. 5A, first, the bottom plate portion 21 which is a part of the outer mold 20 (see FIG. 5C) is installed on the frame, The spacers 30, 30,... Are installed in accordance with the positions of the through holes 21a, 21a,.

  Subsequently, as shown in FIG. 5B, the inner mold 10 is installed on the spacers 30, 30,..., And as shown in FIG. Fit to the communication holes 31a and 32a. Thereafter, the shaft portion of the bolt 40 is inserted into the through hole 21a of the bottom plate portion 21, the communication holes 31a and 32a of the spacer 30, and the through hole 13a of the dam plate layer 10B, and the male screw 41 formed on the shaft portion is attached to the supporting structure 10A. The inner mold frame 10 and the bottom plate portion 21 are connected and fixed by being screwed to the female screw (nut 11b). In the present embodiment, the spacer 30 includes the spacer body 31 and the bearing member 32, and the area of the contact surface of the bearing member 32 is larger than the area of the end surface of the spacer body 31. It is possible to suppress local deformation of the weir plate layer 10B due to the tightening force.

  Next, as shown in FIG. 5C, side plate portions 22, 22 are erected on both ends of the bottom plate portion 21 to form the outer mold frame 20, and between the barrier plate layer 10 </ b> B and the side plate portion 22. The spacers 30, 30,.

  Then, although illustration is abbreviate | omitted, a wife formwork (not shown) is installed so that the opening part before and behind the outer formwork 20 may be plugged up.

(Placement process)
The placing step is a step of placing fresh concrete C ′ around the inner mold 10 as shown in FIG. In the placing process in the present embodiment, fresh concrete C ′ is placed in the space formed between the inner mold 10 and the outer mold 20 and the space above the inner mold 10.

  In addition, when concrete C ′ is placed, a side pressure or the like acts on the inner mold 10 and the outer mold 20, but spacers 30, 30,... Between the inner mold 10 and the outer mold 20. And the inner mold 10 and the outer mold 20 are fixed by bolts 40, 40,..., So that the positional relationship between the inner mold 10 and the outer mold 20 is kept constant. As a result, a concrete structure with high dimensional accuracy can be obtained.

  In addition, when concrete C ′ is placed, buoyancy due to lifting pressure acts on the inner mold 10, but in this embodiment, the inner mold 10 is fixed to the outer mold 20 by bolts 40. Therefore, it is possible to prevent the inner mold 10 from being lifted, and as a result, it is possible to obtain a concrete structure C with high dimensional accuracy.

  In this embodiment, the dam plate layer 10B is composed of a plurality of dam plate constituting members 13, 13,..., But the boundary portion between the adjacent dam plate constituting members 13, 13 is used as a film member 13b or a sealing material. Therefore, it is possible to prevent the intrusion (leakage) of the concrete from the boundary portion between the adjacent weir plate members 13 and 13.

(Primary curing process)
The primary curing process is a process in which the placed concrete C ′ is hardened until it reaches at least the demolding strength. Curing temperature and curing time are set according to the type of concrete C ′.

  In addition, since fiber reinforced concrete tends to have a large amount of self-shrinkage, the shrinkage of the concrete is constrained and remains in the conventional inner formwork using a steel plate or a wooden plate with high rigidity as a dam plate. Although the tensile stress is increased, in this embodiment, the dam plate layer 10B corresponding to the dam plate is formed of bead-method foamed polystyrene having a rigidity lower than that of a steel or wooden dam plate. The shrinkage of 'is not constrained more than necessary, and hence the tensile stress remaining in the concrete C' after hardening can be reduced.

(Outside mold removal process)
The outer mold release process is a process of releasing the outer mold 20 and the unillustrated wife mold, and is performed after the cast concrete C ′ has reached the mold release strength. In order to remove the outer mold 20, the bottom plate portion 21 and the side plate portion 22 may be peeled off after removing the bolts 40, 40,. When the outer mold 20 is removed, the state shown in FIG. In the case of the pretension method, prestress may be introduced into the concrete structure C at the stage where the outer mold 20 is removed.

(Secondary curing process)
The secondary curing process is a process of promoting the strength development of concrete. As shown in FIG. 6C, in the present embodiment, the concrete structure C including the inner mold 10 is placed in the steam curing pot J, and the inside of the steam curing pot J is at normal pressure (atmospheric pressure). The strength of the concrete is promoted by continuously supplying the steam at 90 to 95 ° C. for 40 to 48 hours while maintaining the temperature. In this embodiment, the steam is supplied under normal pressure, but the steam may be supplied in a state where the pressure is increased to the normal pressure or higher.

  When steam curing is performed, the weir plate layer 10B is heated and contracts. When steam at 90 to 95 ° C. is supplied for 40 to 48 hours, the volume of the weir plate layer 10B contracts to about 1/6 to 1/3 before steam curing. Note that the steam (heat) is supplied through the front and rear openings of the support structure 10A and the communication holes 31a and 32a (see FIG. 3) of the spacer 30, so that the entire weir plate layer 10B contracts quickly. . Moreover, in this embodiment, since the dam plate layer 10B is formed by the plurality of dam plate components 13, 13,..., When steam (heat) is supplied, one of the dam plate components 13, 13,. One shrinks and a gap is formed between the adjacent barrier plate members 13 and 13, and this gap functions as a heat and solvent supply path, so the barrier plate layer 10 </ b> B shrinks. It is possible to reduce the time required for the operation.

  The steam curing temperature (that is, the heating temperature of the weir plate layer 10B) may be set according to the scale of the concrete structure C, the type of concrete, etc., but when the steam curing temperature is below 70 ° C., Since the effect of promoting the strength development of the concrete is diminished and the dam plate layer 10B is difficult to shrink, it is preferably set to 70 ° C. or higher, and more preferably set to 80 ° C. or higher. desirable. Further, if the temperature of the steam curing is increased more than necessary, the structure of the hydrated product in the concrete becomes rough, and there is a possibility that long-term durability performance may be lowered.

  In addition, in this embodiment, although the case where steam curing was performed using the steam curing pot J was illustrated, it is not the meaning which limits the method of steam curing. For example, although illustration is omitted, steam curing may be performed by installing the concrete structure C including the inner mold 10 on a pipe for supplying steam. In this case, if the concrete structure C is surrounded by a curing mat, the heat of steam curing can be efficiently supplied to the weir plate layer 10B.

(Inner mold removal process)
The inner mold removal process is a process of removing (removing) the inner mold 10. In the present embodiment, since the dam plate layer 10B is contracted during the steam curing process, the inner mold 10 is simply pulled out from the hollow portion V (see FIG. 7) of the concrete structure C after the steam curing is completed. Good. In addition, even if it returns to normal temperature, since the shrinkage | contraction state of the weir board layer 10B is maintained, it is not necessary to maintain the high temperature state at the time of secondary curing. When the inner mold 10 is removed, a concrete structure C having a hollow portion V is obtained as shown in FIG.

  In the formwork structure 1 according to the present embodiment described above, the inner formwork 10 can be removed if at least the dam plate layer 10B of the inner formwork 10 is contracted. Even when producing a concrete structure C having a large-scale hollow portion V, the amount of beaded polystyrene foam used should be reduced compared to the case where the entire inner mold 10 is made of beaded polystyrene foam. Is possible. That is, according to the method for manufacturing a concrete structure according to the present embodiment, the amount of heat for shrinking the beaded polystyrene can be reduced as compared with the case where the entire inner mold 10 is made of beaded polystyrene. In addition, it is possible to shorten the time until heat reaches the center of the beaded polystyrene foam. In other words, even if the hollow portion V of the concrete structure C is large, this manufacturing method can be applied without difficulty. Moreover, according to this manufacturing method, even if a large restraining force is applied to the inner mold 10 as the concrete shrinks and shrinks, a gap is formed between the concrete structure C and the inner mold 10. Therefore, the inner mold 10 can be easily removed.

  In addition, when the inner mold is formed using foamed polyethylene, even if the foamed polyethylene is heated to be melted or softened and deformed, it is cured again when it returns to room temperature. If the state is not maintained, the demolding operation of the inner mold may be difficult, but if the inner mold 10 is configured using beaded polystyrene as in the present embodiment, it will be at room temperature. Since it is permanently contracted after returning, it is not necessary to maintain a high temperature state during demolding.

  Moreover, in this embodiment, since the rigidity of 10 A of support structures is larger than the dam board layer 10B, there is little deformation | transformation of the inner mold frame 10, Therefore, the manufacture precision of a concrete structure improves. In addition, since the dam plate layer 10B is supported by the support structure 10A having high rigidity, when the inner mold 10 is set, an overload can be applied to the inner mold 10.

  Furthermore, in the formwork structure 1 according to the present embodiment, the support structure 10A is configured to include the frame structure 11 formed by combining rod-like elements, so that the inner formwork 10 can be reduced in weight. It becomes. Further, since the shape and structure of the support structure 10A are simple, the support structure 10A can be manufactured easily and inexpensively. In addition, since the plate-like member 12 is interposed between the barrier plate layer 10B and the frame structure 11, the barrier plate layer 10B can be supported in a plane. Etc. can be suppressed. Further, the support structure 10A according to the present embodiment can be reused many times, which is economical.

  In addition, since the inner mold frame 10 is supported at multiple points by the plurality of spacers 30, no large cross-sectional force is generated in the inner mold frame 10, and deformation due to buoyancy is reduced. That is, the manufacturing accuracy of the concrete structure is improved. Since the supporting structure 10A has high rigidity, the number of the spacers 30 can be reduced as compared with the case where the entire inner mold is made of beaded polystyrene.

  In the present embodiment, steam curing is performed in the secondary curing process, and the case where the volume of the weir plate layer 10B of the inner mold 10 is contracted using the heat of the steam curing is exemplified. When heat curing is performed in the curing process, the volume of the weir plate layer 10B of the inner mold 10 may be contracted using the heat of the heat curing.

  Moreover, you may heat the dam board layer 10B directly, without utilizing the heat | fever of steam curing or heat supply curing. For example, if a heating wire is provided in the support structure 10A, the barrier plate layer 10B can be heated by generating heat from the heating wire. In addition, when the dam plate layer 10B is heated to 270 ° C. or higher with a heating wire, the dam plate layer 10B is melted.

  In the present embodiment, the case where the volume of the barrier plate layer 10B is reduced by heat is exemplified, but in addition to this, a solvent for reducing the volume of the beaded polystyrene foam (for example, limonene-dissolved solution or Nootkaton volume-reducing solution) is used. Supplying to the weir plate layer 10B can also reduce the volume of the weir plate layer 10B.

  The method using a solvent is suitably used when the secondary curing process is not performed, or when the volume reduction of the dam plate layer 10B due to the heat of steam curing or heat supply curing is insufficient.

  In the case of reducing the volume of the dam plate layer 10B using a solvent, for example, although illustration is omitted, after the concrete has reached the demolding strength, the concrete structure C including the inner mold 10B is used as a solvent. What is necessary is just to immerse in the solvent tank which stored this. The outer mold 20 may be immersed in the solvent tank, but preferably, the outer mold 20 is preferably immersed in a state where the outer mold 20 is removed (that is, the bolt 40 is removed). . If immersed in the solvent tank with the bolts 40 removed, the solvent permeates from the communication holes 31a and 32a of the spacer 30, so that the volume of the weir plate layer 10B can be efficiently reduced.

  Of course, the dam plate layer 10B may be reduced in volume by injecting a solvent from the communication holes 31a and 32a of the spacer 30 without being immersed in the solvent tank.

  The configuration of the formwork structure 1 may be changed as appropriate. For example, in the present embodiment, the case where the dam plate layer 10B of the inner mold 10 is arranged on the entire circumference of the support structure 10A is exemplified, but the present invention is not limited to this, and although illustration is omitted, One of the barrier plate layers 10B may be omitted, or one of the left and right barrier plate layers 10B may be omitted. That is, if the weir plate layer 10B is formed on at least one of the pair of opposing surfaces of the supporting structure 10A, the inner mold 10 can be easily removed.

  Further, as described above, there is no particular limitation on the material of the support structure 10A. However, if the framework structure 11 and the plate-like member 12 of the support structure 10A are made of polystyrene resin, the Nootkaton volume reduction solution can be obtained. Since it becomes possible to change the shape into a gel, the demolding operation of the inner mold 10 is further facilitated.

  Further, the configuration of the outer mold 20 is not limited to the illustrated one. For example, although not shown in the figure, when building a concrete structure inside the underground continuous wall or when building a secondary lining that is a concrete structure inside the primary lining of the tunnel, The primary lining of continuous walls and tunnels will function as the outer formwork.

  Moreover, in this embodiment, although the example which hold | maintains the space | interval of the inner mold 10 and the outer mold 20 with the spacer 30 was shown, the inner mold 10 and the outer mold 20 with the separator etc. which were used conventionally are shown. Of course, there is no problem even if the interval is maintained.

  In this embodiment, although the case where the hollow part V of the concrete structure C was a closed cross section was illustrated, it is not the meaning which limits the application range of the manufacturing method of a concrete structure which concerns on this invention, and a formwork structure. The method for producing a concrete structure and the formwork structure according to the present invention can also be applied when the hollow portion V has an open cross section (see FIG. 8C). In addition, as for the hollow part V of the concrete structure C shown to (c) of FIG. 8, the upper surface is opening and it spreads in the back.

  When manufacturing such a concrete structure C, the formwork structure 1 'shown in FIG. 8 (a) may be used.

  The formwork structure 1 ′ includes an inner formwork 110 formed by forming a weir plate layer 110 </ b> B made of a bead method foamed plastic on the outer surface of the support structure 110 </ b> A, and an outer formwork arranged so as to surround the inner formwork 110. 120, spacers 30, 30,... Interposed between the inner mold 110 and the outer mold 120, and bolts (fixing means) 40, 40 for fixing the inner mold 110 and the outer mold 120 to each other. ... and is configured.

  Since the structure of the support structure 110A is the same as the structure of the support structure 10A (see FIG. 1), detailed description thereof is omitted, but the width dimension of the support structure 110A is a concrete structure. It is smaller than the opening width of C.

  The dam plate layer 110 </ b> B is configured by a plurality of dam plate members 113, 113,. In addition, the weir plate constituting material 113 arranged on the side portion of the support structure 110A has a trapezoidal cross section in accordance with the shape of the hollow portion V (see FIG. 8C) spreading in the back.

  Then, after placing the inner mold frame 110 at the position where it becomes the hollow portion V, fresh concrete C ′ is placed around the inner mold frame 110, and after the concrete C ′ reaches the demolding strength, FIG. (B), when the volume of the dam plate layer 110B is reduced using heat or the above-described solvent, the inner mold 110 can be easily taken out from the opening of the hollow portion V without being disassembled. Is possible.

It is sectional drawing which shows the formwork structure which concerns on embodiment of this invention. (A) is a disassembled perspective view which shows a support structure, (b) is a disassembled perspective view which shows an internal mold. It is the A section enlarged view of FIG. It is a graph which shows the heat-shrinkage characteristic of bead method expanded polystyrene. (A)-(c) is sectional drawing for demonstrating each process of the manufacturing method of the concrete structure which concerns on embodiment of this invention. (A)-(c) is sectional drawing for demonstrating each process of the manufacturing method of the concrete structure which concerns on embodiment of this invention, Comprising: The process following the process of (c) of FIG. 5 is demonstrated. FIG. It is sectional drawing which shows a concrete structure. (A) is sectional drawing which shows the modification of a formwork structure, (b) And (c) is sectional drawing for demonstrating the manufacturing method of the concrete structure using the formwork structure shown to (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Formwork structure 10 Inner formwork 10A Support structure 10B Dam plate layer 11 Frame structure 12 Plate member 13 Dam plate component 13b Membrane member 20 Outer frame 30 Spacer 40 Bolt (fixing means)
C Concrete structure V Hollow part

Claims (12)

A method of manufacturing a concrete structure having a hollow part, wherein an inner mold frame formed by forming a bead method foamed plastic dam plate layer on the outer surface of the support structure is disposed at a position to be the hollow part, The volume of the dam plate layer is reduced by placing fresh concrete around the inner mold frame and heating the dam plate layer to 70 to 100 ° C. after the concrete reaches demolding strength. A method for producing a concrete structure, characterized in that: The bead method foamed plastic is bead method foam polystyrene,
The sheathing board layer is heated to thereby shrink the method for producing a concrete structure according to claim 1, characterized in that for volume reduction the volume of the sheathing board layer. The method for producing a concrete structure according to claim 1 or 2 , wherein the barrier plate layer is heated by heat of heat supply curing. The method for producing a concrete structure according to any one of claims 1 to 3 , wherein the dam plate layer is heated by heat of steam curing. The concrete has a diameter of 0.1 to 0.1 in a cement matrix obtained by mixing a high-performance water reducing agent and water in a powder containing cement, a pozzolanic reaction particle, and an aggregate having a maximum particle size of 2.5 mm or less. The production of a concrete structure according to any one of claims 1 to 4 , wherein 1 to 4% by volume of fibers having a shape of 0.3 mm and a length of 10 to 30 mm are mixed. Method. A formwork structure used when manufacturing a concrete structure having a hollow part,
An inner mold for forming the hollow part ;
An outer form for forming the outer surface of the concrete structure;
A spacer that holds a distance between the inner mold frame and the outer mold frame ;
Wherein the mold is then closed and支保structure, and the支保beads method was formed on the outer surface of the structure made of expanded plastic sheathing board layer,
Each of the barrier plate layer and the outer mold frame has a through hole at a position where the spacer is disposed.
A formwork structure in which the spacer is formed with a communication hole connecting the through hole of the barrier plate layer and the through hole of the outer mold frame . The formwork structure according to claim 6 , wherein the support structure includes a frame structure formed by combining rod-shaped elements. The formwork structure according to claim 7 , wherein the supporting structure includes a plate-like member interposed between the barrier plate layer and the frame structure. The formwork structure according to any one of claims 6 to 8 , wherein the supporting structure is made of polystyrene resin. In the support structure, a female screw is formed at a position corresponding to the through hole of the barrier plate layer,
The inner mold frame and the outer mold frame are fixed by screwing a male screw inserted into the through hole of the outer mold frame, the communication hole of the spacer, and the through hole of the barrier plate layer into the female screw. The formwork structure as described in any one of Claims 6 thru | or 9 characterized by these. The formwork structure according to any one of claims 6 to 10 , wherein the barrier plate layer is formed by abutting a plurality of barrier plate constituent materials made of bead method foamed plastic. The formwork structure according to claim 11 , wherein a boundary portion between the adjacent weir plate components is sealed.

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