JP2005030163A - Concrete-steel beam composite structure and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete-steel beam composite structure, in which prestress is effectively adapted without giving unnecessary stress to a steel frame and hard concrete is strongly joined to the steel beam, and a method of manufacturing the composite structure. <P>SOLUTION: This composite structure comprises the steel beam having a bonded surface with a plurality of projections, the first fresh concrete (CC) formed by hardening a first fresh concrete (FC), the second CC formed by hardening a delayed hardening FC, and steel wire for applying stress to the first CC. The first CC is formed such that does not come into contact with a part of the projections though they are positioned adjacent to the bonded surface of the steel beam. The second CC is formed in a hardened material having a shape suitable for a space between the projections and the first CC and formed by hardening the delayed hardening FC after stress is applied to the first CC. In the manufacturing method, stress is applied to the first CC after the first CC is hardened and before the hardening of the delayed hardening FC is completed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a concrete-steel girder composite structure and a manufacturing method thereof.

  A structure in which hardened concrete and a steel girder are combined, such as a composite of a floor slab and a steel girder, or a composite girder in which a steel girder and a concrete girder are combined, is known in Patent Document 1, for example. Usually, in such a structure, in order to prevent the deviation between the hardened concrete and the steel girder, there is provided a detent protrusion called a diver or stud that extends from the steel girder and is buried in or penetrates the hardened concrete. In many cases, a prestressed concrete (PC) is formed in a concrete structure by introducing a prestress for improving the strength. Here, if the concrete and the stopper are firmly attached, there is a problem that the stress introduced into the concrete is introduced to the steel girder through the stopper.

  In order to solve this problem, Patent Document 2 discloses an elastic synthetic girder in which the rigidity of the stopper itself is softened. In this case, the deviation is alleviated, but stress is transmitted to the steel girders.

  Patent Document 1 proposes a composite girder in which a resin having a long curing time is provided between a stopper and cured concrete. In this case, when the resin hardens after the deformation of the hardened concrete due to the introduction of prestress, the prestress is not transmitted to the steel girders, and the steel girders and the hardened concrete are integrated after the resin is hardened.

  However, the synthetic girder of Patent Document 1 has various problems due to the presence of the resin. For example, since resin is generally lower in strength than concrete and steel girders, it is inferior in durability. In addition, the thermal expansion coefficient of the resin is about 10 times that of concrete, and there is a possibility that adhesion to the concrete may be broken due to temperature changes.

  Therefore, in the composite girder, it is conceivable to interpose other materials instead of interposing resin, but it has the same or higher strength and thermal expansion coefficient as concrete and steel girder and has a long curing time. At present, no suitable material has been found as a material to be used.

It is conceivable to use a concrete composition to which a setting retarder is added as an intervening material. However, if a large amount of a setting retarder is added to obtain a sufficient setting delay, material separation of the composition occurs, and a phenomenon such as bleeding occurs, which deteriorates the steel girder and is not practical. This tendency is further strengthened when the temperature generated during curing of concrete is as high as about 95 ° C. On the other hand, if the addition amount of the setting retarder is reduced, it is often hardened until the deformation due to the prestress is completed, which is also not practical. Therefore, no synthetic girder as shown in Patent Document 1 in which concrete is interposed instead of resin has been made so far.
Japanese Patent Laid-Open No. 2002-4475 Japanese Patent Laid-Open No. 10-317324

  An object of the present invention is to provide a concrete-steel girder composite structure in which prestress is effectively introduced without applying unnecessary stress to the steel girder, and the hardened concrete and the steel girder are strongly coupled. .

  Another object of the present invention can be easily implemented, can effectively introduce prestress without giving unnecessary stress to the steel girder, and can strongly bond the hardened concrete and the steel girder. The object is to provide a method for producing a concrete-steel girder composite structure.

  According to the present invention, a steel girder having a joint surface having a plurality of protrusions on at least one surface; a first hardened concrete formed by hardening the first fresh concrete; A second hardened concrete comprising: a steel wire that stresses the first hardened concrete; and the first hardened concrete is adjacent to the joining surface of the steel girder but with at least a portion of the protrusions The second hardened concrete has a shape that fits the gap between the protrusion and the first hardened concrete, and stresses the first hardened concrete. After that, a concrete-steel girder composite structure is provided, which is a cured product obtained by curing the delayed-curing fresh concrete.

  Further, according to the present invention, the delayed-curing fresh concrete comprises a high belite type Portland cement, a setting retarder, a dispersant, a separation reducing agent, a shrinkage reducing agent, and an inorganic admixture. The concrete-steel girder composite structure is provided.

  Further, according to the present invention, the setting retarder is a cement setting retarder which is a lignin sulfonate, oxycarboxylate, gluconate or polyol organic derivative, or a combination thereof; A dispersant comprising a carboxylic acid polymer, a naphthalene sulfonic acid polymer, an alkylallyl sulfonic acid polymer, a melamine sulfonic acid polymer, or a combination thereof; and the separation reducing agent is a cellulose, acrylic, glycol Or a combination of these, the inorganic admixture has an average particle size of 100 μm or less, stone powder, silica fume, blast furnace slag fine powder, fly ash, or a combination thereof Certain said concrete-steel girder composite structures are provided.

  Further, according to the present invention, there is provided a method for producing the concrete-steel girder composite structure, after the first hardened concrete is hardened and before the hardening of the delayed-curing fresh concrete is completed. A manufacturing method is provided, wherein stress is applied to the first hardened concrete.

  Further, according to the present invention, (A) a step of providing the steel beam; (B) a step of placing the delayed-setting fresh concrete around the protrusion of the steel beam; (C) the first fresh wall Placing concrete in a form adjacent to the joint surface of the steel beam but not in contact with at least a portion of the protrusion; (D) curing the first fresh concrete to form the first hardened concrete; And (E) applying a stress to the first hardened concrete, wherein the step (E) is performed before the setting of the delayed-curing fresh concrete is completed. Is provided.

  The concrete-steel girder composite structure of the present invention is a structure in which prestress is effectively introduced without applying unnecessary stress to the steel girder, and the hardened concrete and the steel girder are strongly coupled. It is useful as a composite of PC slab and steel girders.

  In addition, the method for producing a concrete-steel girder composite structure of the present invention can be easily implemented, can effectively introduce prestress without applying unnecessary stress to the steel girder, and can be used for hardening concrete and steel girder. It is useful as a production method capable of binding strongly to each other.

Hereinafter, the present invention will be specifically described with reference to the drawings.
The steel girder in the concrete-steel girder composite structure of the present invention has a joint surface having a plurality of protrusions on at least one surface. Like the bonding surface 101 shown in FIG. 1, the bonding surface is typically a flat surface other than a portion having a protrusion, but may be a curved surface or a surface with unevenness. Further, as in the joining surfaces 201a and 201b shown in FIG. 2, one or more first hardened concretes may be provided across two or more surfaces separated from each other.

  There are two or more protrusions corresponding to one first hardened concrete. If the joint surfaces are a plurality of two or more surfaces separated from each other, there are one or more on each surface, such as the projections 202a and 202b shown in FIG. It may correspond to.

  The shape of the protrusion is not particularly limited, and can be a known gibber or stud. The protrusions may have a structure adapted to be partially or wholly present in the second hardened concrete, and preferably have a root at the second hardened concrete, such as the protrusion 302a shown in FIG. 3A. It is possible to make the structure suitable for being present in 305a and having the tip existing in the first hardened concrete, but is not limited to this. For example, the second hardened concrete like the protrusion 302b shown in FIG. 3B. A structure suitable for being present only in 305b can also be used.

  The first hardened concrete in the concrete-steel girder composite structure of the present invention is formed by hardening the first fresh concrete. In the present specification, for the sake of convenience, a composition containing cement or the like that has not been cured is referred to as fresh concrete, and a cured composition is referred to as cured concrete.

  The first fresh concrete is not particularly limited and can be a fresh concrete that is usually used to create a composite with a steel girder, but a fresh concrete that hardens to be stressed with a somewhat short curing period is preferable. . Specifically, for example, fresh concrete containing early strength Portland cement or other Portland cement as cement and further containing fine aggregate, coarse aggregate, inorganic admixture, water reducing agent and the like can be used. In the present specification, concrete refers to a composition cured by cement and a cured product thereof, and includes cement paste, mortar, and the like.

  The first fresh concrete may be formed by placing a formwork on a steel girder and cured to form the first cured concrete, or may be combined with the steel girder after it has been cured in advance. When a formwork is provided on a steel girder and placed and cured, it is necessary to cure the first fresh concrete before the delayed-curing fresh concrete is cured.

  The first hardened concrete has a shape adjacent to the joining surface of the steel beam but not in contact with at least a part of the protrusion. Specifically, the joint surface can be in contact with the steel girder and can have a shape having a recess that covers each of the plurality of protrusions via a gap. Specifically, for example, the first hardened concrete 103 shown in FIG. 1 may have a structure in contact with the steel girders over substantially the entire joining surface 101, or, for example, the second hardened concrete shown in FIG. Like 203, it can also be set as the structure which touches the steel girders 206a and 206b in a part of each of the joint surfaces 201a and 201b.

  Specifically, for example, as shown in FIGS. 3A to E, the shape of the recess is directly embedded in the first hardened concrete (303a to e), and the base of the protrusion is first, as shown in FIGS. It can be a gap (A, E) that comes into contact with the second hardened concrete (305a to 305e), or a gap (B, C, D) in which the entire protrusion is buried in the second hardened concrete. By forming a concave shape so that at least the base of the protrusion contacts the second hardened concrete, when the first hardened concrete is stressed before the second hardened concrete is completely hardened, the stress is introduced to introduce steel. Even if there is a deviation as shown in Fig. 4 in the position between the girder and the first hardened concrete, the protrusion moves from the position shown by the dotted line to the position shown by the solid line in the recess, so that the steel girder is stressed. Can be prevented, and when the delayed-curing fresh concrete is later cured, a strong steel girder-hardened concrete bond can be obtained.

  Further, the recess may have an opening only on the surface of the first hardened concrete in contact with the steel beam (A, B), or it may have an opening on a surface other than the surface in contact with the steel beam. It may be of a shape (C, D, E) adapted to inject delayed-curing fresh concrete into the void after joining with the spar. The concave portion here also includes a through hole as shown in FIG. 3C for convenience. It is preferable that the recess has an opening only on the surface in contact with the steel beam because there is no problem of unevenness on the concrete surface due to the thinning of the delayed-curing concrete.

  The second hardened concrete in the concrete-steel girder composite structure of the present invention is formed by hardening delayed-hardening fresh concrete.

  Here, the delayed-curing fresh concrete refers to fresh concrete which has a slower curing speed than normal fresh concrete and hardens after 4 days from placing. More specific embodiments of the delayed-curing fresh concrete will be described later in detail.

  The shape of the second hardened concrete has a shape that fits the gap between the protrusion and the first hardened concrete. Specifically, a shape in which all or a part of the concave portion of the first hardened concrete can be filled, but a shape in which the whole concave portion is filled is preferable in terms of developing strength.

  In the concrete-steel girder composite structure of the present invention, the second hardened concrete may be in direct contact with the first hardened concrete, through a formwork for placing delayed-hardening fresh concrete, which will be described later, and the like. You may touch. As the mold, an embedded mold made of steel or plastic can be used. In addition, when using delayed-curing fresh concrete with low fluidity, the second hardened concrete may be in direct contact with the first hardened concrete by forming it in the same shape without using a formwork. it can.

  In the concrete-steel girder composite structure of the present invention, the second hardened concrete is a hardened material that is hardened after applying stress to the first hardened concrete.

  In the concrete-steel girder composite structure of the present invention, the steel wire that applies stress to the first hardened concrete can be the one used in ordinary PCs. The arrangement direction of the steel wire is not particularly limited, but the direction parallel to a straight line passing through a plurality of points fixed to the steel beam by protrusions in the first hardened concrete (hereinafter referred to as “D direction”; for example, FIG. 1 and In FIG. 2, the steel wire is preferably arranged in at least one direction in the direction indicated by arrow D) or in the direction close to D direction. In one first hardened concrete, for example, when there are fixing points due to protrusions in the vertical and horizontal directions, there will be a plurality of D directions. In that case, the steel wire is in one direction or two or more of them. Can be arranged. Further, instead of the D direction or in addition to the D direction, the steel wires can be arranged in other directions. Further, the number of steel wires per direction is not particularly limited, and one or a plurality of steel wires can be arranged according to the desired strength or the like.

  The steel wire can be provided in the first hardened concrete together with a structure such as a sheath and grout used together with the steel wire in a normal PC. Here, as the grout, a grout having the same composition as the delayed-curing fresh concrete can be used, or a mortar having a composition obtained by removing the aggregate from the retarding-curing fresh concrete can be used. Compositions can also be used.

  The concrete-steel girder composite structure of the present invention can be a variety of structures in which PC and steel girder are preferably integrated, such as a composite girder, a steel girder and PC floor slab composite structure.

  The method for producing a concrete-steel girder composite structure of the present invention includes a step of applying stress to the first hardened concrete after the first hardened concrete is hardened and before the hardening of the delayed-curing fresh concrete is completed. including. In the production method of the present invention, the concrete-steel girder composite structure is manufactured by concrete construction such as concrete-steel girder composite structure by construction on site, and composite girder etc. that is pre-manufactured in the factory before being transported to the site. -Includes both manufacture of steel girder composite structures.

  Specifically, in the method for producing a concrete-steel girder composite structure of the present invention, after providing the steel girder, the delayed-curing fresh concrete and the first fresh concrete are placed in a desired shape, and the first This can be done by curing the fresh concrete to form the first hardened concrete and applying stress to the first hardened concrete before the delayed-curing fresh concrete is fully cured.

  These steps can be performed in any order as long as stress is applied to the first hardened concrete after the first hardened concrete is hardened and before the hardened of the delayed-curing fresh concrete is completed. Good. For example, the first fresh concrete can be cast on the steel girder interface either before or after the delayed setting fresh concrete is cast, or the first fresh concrete is pre-cured and precast. It is also possible to prepare hardened concrete and place it on the steel girder interface, either before or after the placement of the delayed-curing fresh concrete.

  From the viewpoint of performing a simple process and obtaining a composite structure in which hardened concrete and steel girders are securely bonded by sufficiently filling with delayed-hardening fresh concrete, first, delayed-hardening fresh concrete is placed, Then, it is preferable to place the first fresh concrete thereon. That is, the following steps (A) to (E) are preferably performed in this order:

(A) a step of providing a steel beam;
(B) a step of placing delayed-hardening fresh concrete around the projection of the steel beam;
(C) providing the first fresh concrete in a form adjacent to the joint surface of the steel beam but not in contact with at least a part of the protrusion;
(D) curing the first fresh concrete to form the first hardened concrete; and
(E) A step of applying stress to the first hardened concrete.

  In the step (B), the step of placing delayed-hardening fresh concrete around the steel girder protrusion is, for example, as shown in FIG. This can be done by filling with fresh concrete 511.

  In the step (C), the step of placing the first fresh concrete is, for example, as shown in FIG. 5, after placing the delayed curable fresh concrete 511, the first fresh concrete 513 is placed in the mold 512. This can be done by filling. At this time, the step (D) and the step (E) are not particularly limited and can be performed according to a normal PC manufacturing method, but the step (E) is performed before the hardening of the delayed-curing fresh concrete is completed. To be done. In the manufacturing method according to the steps (A) to (E), after the setting of the delayed-curing fresh concrete, the first fresh concrete is cast and cured, and the delayed-curing fresh concrete is cured until stress is introduced. However, as the delayed-curing fresh concrete that enables such a process, specifically, delayed-curing fresh concrete described later can be used.

Delay-curing fresh concrete As the retarding-curing fresh concrete used in the present invention, it is preferable to use fresh concrete containing high belite type Portland cement, a setting retarder and a dispersant. By including such a component, it is possible to obtain fresh concrete having a very long setting time and a high compressive strength when cured.

As the delayed-curing fresh concrete, it is preferable to use high belite-type Portland cement as the cement because a long setting time can be secured and self-shrinkage can be reduced. As the high belite-type Portland cement, one containing belite (2CaO · SiO ₂ ) of 24% by mass or more, preferably 40% by mass or more can be used. In particular, the use of belite containing 40% by mass or more is preferable because the setting time can be greatly delayed. Moreover, it is preferable that the high belite type Portland cement has a specific surface area of 4000 cm ² / g or less because the hydration reaction and the amount of self-shrinkage can be suppressed.

  Examples of the setting retarder include lignin sulfonates, oxycarboxylates, gluconates, polyol organic derivatives or combinations thereof, and it is particularly preferable to use polyol organic derivatives.

  Examples of the dispersant include polycarboxylic acid polymer compounds, naphthalene sulfonic acid polymer compounds, alkylallyl sulfonic acid polymer compounds, melamine sulfonic acid polymer compounds, or combinations thereof. It is preferable to use a polycarboxylic acid polymer compound because the fluidity and the like can be improved with a low blending amount.

  In addition to the above-described components, the delayed-setting fresh concrete can further include an inorganic admixture, a separation reducing agent, an organic shrinkage reducing agent, an aggregate, or a combination thereof. The inorganic admixture preferably has an average particle size of 200 μm or less, more preferably 100 μm or less. As the inorganic admixture, stone powder such as limestone fine powder, silica fume, blast furnace slag fine powder, fly ash, or a combination thereof can be used. The separation reducing agent is preferably one that can maintain the separation reduction effect even in an environment heated by the heat of hardening of the concrete in the production method of the present invention, for example, at a high temperature of 90 ° C., specifically, cellulose-based, Acrylic, glycol-based or starch-based separation reducing agents or combinations thereof can be used, and cellulose ether-based separation reducing agents are particularly preferred. As the organic shrinkage reducing agent, an alkylene oxide adduct system of a lower alcohol, a polyether system, an alcohol system, a low molecular weight alkylene oxide copolymer system or a glycol ether / amino alcohol derivative system or a combination thereof may be used. it can. The aggregate may include fine aggregate and coarse aggregate having an average particle size of 150 μm or more and 40 mm or less.

  The delayed-curing fresh concrete can contain various components such as water, a swelling agent, a rust inhibitor, and an antifoaming agent in addition to the above-described components.

  In the delayed-curing fresh concrete, the water powder ratio, that is, the mass ratio of water to the total of the high belite light Portland cement and the inorganic admixture is preferably 20 to 50%.

  In the delayed-curing fresh concrete, the mass ratio of the high belite-based Portland cement and the inorganic admixture is preferably 2: 8 to 8: 2. By adopting this blending, the curing delay time of fresh concrete can be made sufficiently long, bleeding can be prevented, and the amount of self-shrinkage can be reduced.

  The blending ratio of the dispersant can be 0.05 to 3.5 parts by mass with respect to 100 parts by mass in total of the high belite type Portland cement and the inorganic admixture. By using this formulation, workability required for construction can be sufficiently secured.

  The blending ratio of the setting retarder can be 0.15 to 1.0 part by mass with respect to 100 parts by mass in total of the high belite type Portland cement and the inorganic admixture. By using this formulation, it is possible to obtain a long-lasting curing delay of several days or longer.

  The mixing ratio of the separation reducing agent is preferably 0.05 to 1.0 part by mass with respect to a total of 100 parts by mass of the high belite type Portland cement and the inorganic admixture. By adopting this blending, bleeding can be sufficiently suppressed even in a temperature condition during concrete curing, for example, at a high temperature of about 90 ° C., and also in a long curing period of several days or more.

  The blending ratio of the organic shrinkage reducing material is preferably 0.1 to 3.0 parts by mass with respect to 100 parts by mass in total of the high belite type Portland cement and the inorganic admixture. By using this blend, the self-shrinkage of fresh concrete can be sufficiently reduced.

  For delayed-curing concrete, the mass ratio of high belite-based Portland cement and inorganic admixture is 2: 8 to 8: 2, and the total amount of high-belite cement and inorganic admixture is 100 parts by weight. 0.05 to 3.5 parts by weight of dispersant, 0.15 to 3.0 parts by weight of cement setting retarder, 0.05 to 1.0 parts by weight of separation reducing agent, 0.1 to 3.0 parts by weight of organic shrinkage reducing agent, and 200 to 800 parts by weight of aggregate And those containing 20 to 60 parts by weight of kneaded water are particularly preferred because they can ensure the curing delay time, prevent bleeding and reduce the amount of self-shrinkage.

  The manufacturing method of delayed-setting fresh concrete is not specifically limited, It can prepare by mix | blending and mixing each component in a factory and / or a construction site.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited to these.

Example 1
(Preparation of delayed-curing fresh concrete)
The materials shown in Table 1 were mixed to prepare delayed-setting fresh concrete having the composition shown in Formulations 1 to 14 in Table 1. The materials used and their abbreviations shown in the table are as follows. In addition, Table 2 shows the ratios of various components in each fresh concrete of Formulations 1 to 14.

(Materials used)
I. Cement and low heat Portland cement (abbreviation: LC): Belite content = 54%, density = 3.22 (manufactured by Taiheiyo Cement Co., Ltd.)
-Ordinary Portland cement (abbreviation: NC): Belite content = 24%, density = 3.15 (manufactured by Taiheiyo Cement Co., Ltd.)
II. Cement dispersant / polycarboxylic acid cement dispersant (abbreviation: PC): Commercially available product (trade name: Koaflow NF-100, manufactured by Taiheiyo Materials Co., Ltd.)
・ Naphthalenesulfonic acid cement dispersant (abbreviation: N): Commercial product (trade name: Mighty 100, manufactured by Kao Corporation)
III. Inorganic admixtures and silica fume (abbreviation: SF): Density = 2.2, Specific surface area = 200,000cm ² / g, Commercial product (Product name: Microsilica 940U, manufactured by Elchem)
・ Limestone fine powder (abbreviation: LSP): Density = 2.67, specific surface area = 3840cm ² / g, commercial product (trade name: Industrial Tankar, manufactured by Yoshizawa Lime Industry Co., Ltd.)
IV. Cement setting retarder / oxycarboxylic acid compound and polyol organic polymer composite cement setting retarder: (Product name: Pozzolith No.89, manufactured by NMB)
V. Separation-reducing agent / cellulose-based separation reducing agent (abbreviation: V): Commercially available product (trade name: Marporose, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.)
VI. Organic shrinkage reducing agent / Organic shrinkage reducing agent (abbreviation: SR): Organic shrinkage reducing agent Oxyalkylene alkyl ether type (manufactured by Taiheiyo Cement Co., Ltd.)
VII. Fine aggregate (abbreviation: S): Crushed sand (Surface dry specific gravity = 2.61, FM = 2.80, Iwase-cho, Ibaraki-gun)
VIII. Coarse aggregate (abbreviation: G): Crushed stone (surface dry specific gravity = 2.63, FM = 6.78, Iwase-cho, Ibaraki-gun)
IX. Expansive material (abbreviation: E): Lime-based expansive material, density = 3.15, trade name: structural expansion, manufactured by Taiheiyo Materials Co., Ltd.)
X. Mixing water (abbreviation: W) Tap water

(Other abbreviations in the table)
C: Cement
B: Mass of binder (cement + silica fume + expansion material)
P: Powder mass (cement + silica fume + expansion material + limestone fine powder)
s / a: Fine aggregate ratio (ratio of fine aggregate volume to aggregate total volume)

(Delay-curing concrete test)
Various tests as described below were conducted on the delayed-curing fresh concrete of Formulations 1 to 14 obtained in Example 1 and its cured product. The results are shown in Table 3. The ambient temperature during curing was set to 20 ° C. according to the curing pattern shown in FIG. 6 on the first day after mixing.

(Test method)
I. Fresh concrete slump: “Measured according to the concrete slump test method (JIS A 1101-1998).
II. Bleeding of fresh concrete: “Measured in accordance with a concrete bleeding test method (JIS A 1123-1997).
III. Setting time of fresh concrete: Measured according to “Method of testing setting time of concrete (JIS A 1147-2001)”.
IV. Constrained Expansion and Shrinkage of Concrete: Measured in accordance with “Constrained Expansion and Shrinkage Test Method for Expanded Concrete in Appendix 2 of Concrete Expansion Material (JIS A 6202-1997)”.
V. Compressive strength of concrete: Measure in accordance with “Concrete compressive strength test method (JIS A 1108-1999)”.
VI. Fluidity of concrete: Measured in accordance with “Flow test of physical test method of cement (JIS A 5201-1997)”.

(Manufacture of concrete-steel girder composite structures)
A steel or plastic formwork for placing a delayed hardening concrete structure around the steel girders 202a and 202b of the shape shown in FIG. In addition, a formwork for placing floor slabs 203 and 204, a reinforcing bar, and a sheath of steel wire for introducing prestress were assembled.

  Fill the formwork around the gibber for delayed-setting concrete with the delayed-setting fresh concrete with compound number 1-14, or use the formwork for delayed-setting fresh concrete with low fluidity It was provided around the dowel so as to have the same shape as the case. Further, a steel material was inserted into the sheath, and grout was injected.

  Immediately thereafter, concrete containing water, early-strength Portland cement, fine aggregate, coarse aggregate and water reducing agent in the composition shown in Table 4 below was placed in the part of the formwork floor slab, and cured for 7 days. did. In addition, when this concrete temperature exceeds 25 degreeC, the casting temperature of concrete will be 30 degreeC or more, and the temperature of concrete will be 90-95 degreeC at the time of curing for one day. During the curing of the concrete, the temperature of the concrete reached about 95 ° C. After finishing the curing of the slab, it was confirmed by a concrete setting test that the grout and the delayed-curing fresh concrete had not yet been cured, and tension was applied to the steel material. After further curing for 7 days, the delayed-curing concrete was cured to obtain a PC slab-steel girder composite structure.

The obtained composite structure was tested for bonding between the steel girder and the PC slab, and it was confirmed that both were well bonded.

  Moreover, in the obtained composite structure, it was tested whether the prestress introduced into the floor slab was transmitted to the steel girder by the strain gauge attached to the steel girder, and no stress was transmitted to the steel girder. Was confirmed.

When the delayed-curing fresh concrete of the blending numbers 7, 13, and 14 is used, bleeding does not occur, the adhesion with the first hardened concrete is good, the initial setting time is as slow as 5 days or more, and the compressive strength is A particularly preferable result was obtained, which was 50 N / mm ² or more exceeding the design standard strength of the PC floor slab, 40 N / mm ² .

FIG. 1A is a perspective view schematically showing an example of the concrete-steel girder composite structure of the present invention, FIG. 1A is a cross-sectional view taken along line bb ′ (FIG. 1B), and FIG. FIG. 1C is a cross-sectional view taken along the line (FIG. 1C). FIG. 2A is a perspective view schematically showing another example of the concrete-steel girder composite structure of the present invention (FIG. 2A), a cross-sectional view along line bb ′ of FIG.2A (FIG. 2B), and a line c-- of FIG. FIG. 2C is a cross-sectional view along c ′ (FIG. 2C). It is sectional drawing which shows the various aspects around protrusion in the concrete-steel girder composite structure of this invention. It is sectional drawing explaining the formation method of the structure around protrusion in the concrete-steel girder composite structure of this invention. It is the schematic which shows the principle of absorption of the deformation | transformation by prestress in the concrete-steel girder composite structure of this invention. It is a graph which shows the pattern of the ambient temperature of the curing on the 1st day after kneading | mixing in the case of the test of the delay-hardening concrete in Example 1. FIG.

Explanation of symbols

101,201a, 201b: Contact surface
102,202a, 202b, 302a-e, 502: Protrusions (dive)
103, 203, 204, 303a-e: First hardened concrete (floor slab)
206a, 206b: Steel girders
305a-e: second hardened concrete (delay hardening)
510: Formwork
511: Delay-curing fresh concrete
512: Formwork
513: 1st fresh concrete

Claims (5)

A steel beam having a joining surface having a plurality of protrusions on at least one surface;
A first hardened concrete formed by hardening the first fresh concrete;
A second hardened concrete obtained by hardening delayed-curing fresh concrete;
A steel wire that stresses the first hardened concrete;
The first hardened concrete has a shape adjacent to the joining surface of the steel beam but not in contact with at least a part of the protrusion, and the second hardened concrete is formed of the protrusion and the first hard concrete. A concrete having a shape suitable for a gap between the hardened concrete and a hardened product obtained by curing the delayed-curing fresh concrete after applying stress to the first hardened concrete Steel girder composite structure.   2. The delayed-curing fresh concrete is a composition comprising high belite-based Portland cement, a setting retarder, a dispersant, a separation reducing agent, a shrinkage reducing agent, and an inorganic admixture. Concrete-steel girder composite structure. The setting retarder is a cement setting retarder which is a lignin sulfonate, oxycarboxylate, gluconate or polyol organic derivative or a combination thereof,
The dispersant is a dispersant comprising a polycarboxylic acid polymer, a naphthalene sulfonic acid polymer, an alkylallyl sulfonic acid polymer, a melamine sulfonic acid polymer, or a combination thereof.
The separation reducing agent is a cellulose-based, acrylic-based, glycol-based, or starch-based separation reducing agent, or a combination thereof.
3. The concrete-steel girder composite structure according to claim 2, wherein the inorganic admixture has an average particle diameter of 100 μm or less, and is stone powder, silica fume, blast furnace slag fine powder, fly ash, or a combination thereof.   The method for producing a concrete-steel girder composite structure according to any one of claims 1 to 3, wherein the delayed-curing fresh concrete is completely cured after the first cured concrete is cured. Before, the manufacturing method characterized by applying stress to the first hardened concrete. (A) providing the steel beam;
(B) placing the delayed-curing fresh concrete around the protrusion of the steel beam;
(C) placing the first fresh concrete in a form adjacent to the joint surface of the steel beam but not in contact with at least a part of the protrusion;
(D) curing the first fresh concrete to form the first hardened concrete; and
(E) including a step of applying stress to the first hardened concrete,
5. The method according to claim 4, wherein the step (E) is performed before the delayed-curing fresh concrete is completely cured.

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