JP7122218B2 - Manufacturing method of concrete structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a manufacturing method (construction method) of a concrete structure using a curing sheet.

BACKGROUND ART As a construction method for constructing concrete structures such as bridges and dams, the construction method described in Patent Document 1 has been newly used. In this method, a form for placing concrete is installed, and concrete is placed in a state in which a water-impermeable curing sheet is previously fixed to the inner surface of the form. After the concrete is cast, the formwork is removed, but the curing sheet is left on the concrete side, and the cast concrete is covered with the curing sheet as it is, so that the concrete is cured for a long period of time.

Japanese Patent No. 5698304 Japanese Patent Application Laid-Open No. 2009-084900

In the above construction method, since it is necessary to leave the curing sheet on the concrete when the formwork is removed, the curing sheet is fixed to the concrete using holding members such as holding pins or double-sided adhesive tape. . However, work such as installation of the holding member and attachment of the double-sided adhesive tape is required, which is time-consuming.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a method for manufacturing a concrete structure that allows a curing sheet that has been used before concrete is placed to be more easily left on the concrete. intended to

A method for manufacturing a concrete structure according to the present invention comprises the steps of preparing a plurality of forms configured to define a space inside; preparing a cylindrical or bag-like curing sheet; A step of stacking frames and placing a cylindrical or bag-shaped curing sheet inside the stacked form, fixing one end of the curing sheet to the base, and fixing the one end of the curing sheet It comprises a step of placing concrete inside, and a step of curing the hardened concrete with a curing sheet after the cast concrete has hardened. In this manufacturing method, the casting step is performed after a plurality of molds are arranged outside the curing sheet and the curing sheet is supported by the plurality of molds.

In this concrete structure manufacturing method, the shape of the curing sheet is cylindrical or bag-like so that when the concrete hardens, the concrete structure can be covered with the curing sheet as it is. Therefore, the curing sheet that has been used before concrete is placed can be left on the concrete without using a holding member, an adhesive tape, etc., and the curing sheet can be left on the concrete more easily. Moreover, in this manufacturing method, concrete is placed after a plurality of forms are arranged outside the curing sheet and the curing sheet is supported by the plurality of forms. Therefore, the concrete placed in the curing sheet can be firmly held by the formwork.

In the method for manufacturing a concrete structure described above, in the step of arranging, the cross-sectional area along the horizontal direction of the cylindrical or bag-shaped curing sheet is the horizontal direction of the space formed inside the plurality of forms. It is preferably smaller than the cross-sectional area. In this case, the self-weight of the concrete on which the curing sheet is placed allows it to extend (spread) slightly outward, and wrinkles can be prevented from occurring in the curing sheet in contact with the concrete surface. As a result, transfer of wrinkles to the surface of the concrete structure cured by the curing sheet can be suppressed. In addition, the cross-sectional area along the horizontal direction of the curing sheet before placing concrete is 0.0006% to 0.6% of the cross-sectional area along the horizontal direction of the space formed inside the formwork. can be as small as In this case, while maintaining the performance as a curing sheet, the sheet can be stretched to some extent and the occurrence of wrinkles can be more suitably prevented.

The method for manufacturing a concrete structure may further comprise a step of demolding the plurality of formwork with the curing sheet adhered to the concrete after the poured concrete has hardened. In this case, the curing sheet can be left on the concrete, and the demolded formwork can be used at another site. Each of the plurality of molds is preferably a lightweight mold made of plastic or carbon. In this case, the installation work of the formwork can be easily performed. In addition, a steel formwork may be sufficient as a formwork.

The method of manufacturing a concrete structure described above may further comprise a step of installing a guide on the base, and the guide may be passed through a through-hole provided in the formwork to stack the formwork. In this case, the forms can be aligned and stacked, and the forms after being stacked can be stabilized. In the method for manufacturing a concrete structure described above, the formwork may have a configuration that allows it to be fitted with another formwork in the vertical direction, and the formwork may be stacked using this configuration in the step of arranging. . In this case, the installation work of the guide becomes unnecessary, and the whole work of stacking the forms can be simplified. It should be noted that the formwork may have a configuration that allows it to be fitted with another formwork in the vertical direction, and may be further provided with a through hole so that the formwork can be stacked using a guide.

In the concrete structure manufacturing method described above, in the step of placing concrete, the concrete may be placed in a state in which a predetermined tension is applied to the curing sheet from one end to the opposite side. In this case, the curing sheet in contact with concrete can be further prevented from being wrinkled, and as a result, the transfer of wrinkles to the surface of the concrete structure cured by the curing sheet can be suppressed.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a concrete structure can be provided which leaves the curing sheet used before concrete is poured more easily on concrete.

(a) to (d) of FIG. 1 are diagrams showing an example of a method for manufacturing a concrete structure according to the present invention. 2(a) and 2(b) are diagrams showing an example of a mold used in the manufacturing method shown in FIG. 1. FIG. 3 is a perspective view showing an example of a cylindrical curing sheet used in the manufacturing method shown in FIG. 1. FIG. FIGS. 4(a) to 4(c) are diagrams showing another example of the concrete structure manufacturing method according to the present invention. (a) and (b) of FIG. 5 are diagrams showing a modified example of fixing the curing sheet to the base. FIG. 6 is a schematic diagram showing the contact angle of water on the surface of a modification of the curing sheet used in the present production method.

Hereinafter, a method for manufacturing a concrete structure according to the present invention will be described with reference to the drawings. In the description, the same reference numerals may be used for the same elements or elements having the same functions, and overlapping descriptions will be omitted.

This method of manufacturing a concrete structure includes the steps of preparing a guide and formwork, preparing a cylindrical or bag-like curing sheet, fixing one end of the curing sheet to a base, and forming a plurality of molds. A step of stacking frames and arranging a curing sheet inside the stacked formwork, a step of placing concrete inside the curing sheet after fixing one end, and a step of curing after the cast concrete has hardened. and a step of curing the concrete as it is with a curing sheet. In this manufacturing method, since a cylindrical or bag-shaped curing sheet is used, columnar concrete such as a prism or a cylinder can be easily constructed. Other shapes of concrete structures may be constructed. In the following, the case of constructing a square pole concrete structure will be described as an example, but the present invention may be applied to a cylindrical concrete structure or to concrete structures of other shapes.

(a) to (d) of FIG. 1 are diagrams showing an example of a method for manufacturing a concrete structure according to the present invention. As shown in FIG. 1(a), in this manufacturing method, first, on a base B made of concrete or the like that has already been cast, H steels and angles are attached to the locations corresponding to the four corners of the prismatic concrete structure to be constructed. Alternatively, guides 1 for lightweight forms such as channels are installed respectively. The four guides 1 are thereby fixed to the base B. As shown in FIG. The base B may be other than cast concrete, and may be, for example, bedrock.

Next, a plurality of mold frames 10 each having a frame shape and a cylindrical curing sheet 20 are prepared. As shown in FIG. 2A, the mold 10 is, for example, a rectangular frame 12, and has through holes 14 at its four corners. The through-hole 14 is a positioning mechanism for inserting the above-described guide 1 therein to determine the position of the formwork 10 . The formwork used in this manufacturing method may be the integral formwork 10 shown in FIG. (See (b) of FIG. 2). In addition, the formwork is not limited to a square, but may be rectangular, circular, elliptical, or triangular, as long as it is configured to define a space for pouring concrete inside. It may be a mold for a square frame. The formwork 10 can have a suitable shape according to the shape (cross-sectional shape, etc.) of the concrete structure to be manufactured. Further, considering the workability, it is preferable to use a lightweight formwork made of plastic or carbon as the formwork 10, but a steel formwork may also be used.

The curing sheet 20, as shown in FIG. is provided with an upper tab 26 for hooking. When the curing sheet 20 is bag-shaped, it may have a shape in which the bottom is closed. The curing sheet 20 has a thickness of approximately 0.02 mm to 2.0 mm. Moreover, the cross-sectional area along the horizontal direction of the curing sheet 20 before pouring concrete is 0.0006% to 0.000% of the cross-sectional area along the horizontal direction of the space formed inside the formwork 10 . The curing sheet 20 may be such that it becomes about 6% smaller. In addition, the cross-sectional area along the horizontal direction of the curing sheet 20 here means the cross-sectional area of the outer shape of the curing sheet 20 .

The curing sheet 20 is made of, for example, polypropylene, nylon, nylon 6, perfluoroalkoxy fluororesin, tetrafluoroethylene/hexafluoropropylene copolymer, ethylene/tetrafluoroethylene copolymer, polyethylene terephthalate (PET). , polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, and polyolefin. Among them, by using a sheet composed of polypropylene, polyethylene terephthalate, polyvinylidene chloride, or polyvinyl chloride, it is possible to provide a more inexpensive curing sheet, which can be left on the concrete surface even after demolding. can easily extend the curing period of concrete.

When the plurality of molds 10 and the cylindrical curing sheet 20 are prepared, next, the lower tab 24 of the curing sheet 20 is placed below the first-stage mold 10 and on the base B. Place (one end). Then, the mold 10 is moved downward (to the base B) while passing the guide 1 through the through hole 14 of the mold 10, and the lower tab 24 is sandwiched between the mold 10 and the base B of the first stage. Thereby, the lower end of the curing sheet 20 is fixed to the base B as shown in FIG. 1(b). At this time, if the curing sheet 20 is a thin sheet that does not stand on its own, as shown in the figure, it will be crushed so that the upper part spreads outward (the upper part is omitted), but if it is a self-supporting curing sheet, It is also possible to make it stand on its own.

Subsequently, when the fixing of the lower end of the curing sheet 20 to the base B is completed, a plurality of forms 10 are piled up in order on the form 10 of the first stage installed first. At this time, the molds 10 are arranged so that the guides 1 pass through the through holes 14 of the molds 10 . On the other hand, the curing sheet 20 is attached so as to be caught above the formwork 10 while stretching the sheet when the formwork 10 is stacked. Thereby, as shown in (c) of FIG. 1 , the cylindrical curing sheet 20 is arranged inside the stacked forms 10 . In this case, the horizontal cross-sectional area of the cylindrical curing sheet 20 is preferably smaller than the horizontal cross-sectional area of the space formed inside the mold 10 . That is, it is preferable that a gap is formed between the inner peripheral surface of the mold 10 and the outer peripheral surface of the curing sheet 20 . By maintaining such a relationship, when concrete is placed inside the curing sheet 20, the curing sheet 20 preferably extends and spreads, and wrinkles are less likely to occur. Adhesion to concrete can be improved.

Subsequently, when the stacking of the formwork 10 and the installation of the curing sheet 20 in the formwork 10 are completed, a predetermined amount of concrete is placed inside the cylindrical curing sheet 20 . As a result, a hardened concrete or a predetermined concrete structure C is constructed in the curing sheet 20 . When pouring the concrete, the upper or upper tab 26 of the curing sheet 20 may be pulled upward, and the concrete may be placed in a wrinkle-free state. When the sheet is pulled, if the elongation rate of the curing sheet 20 is 0.001% or more, the sheet does not sag, which is preferable. Thereafter, when the compaction of the concrete is completed, curing of the concrete is performed for, for example, about 3 to 28 days while the formwork 10 is still in place to accelerate the hydration reaction of the concrete.

Subsequently, when the placed concrete hardens, the formwork 10 is removed and the hardened concrete is cured with the curing sheet 20 as shown in FIG. 1(d). At this time, since the curing sheet 20 has a cylindrical shape, the curing sheet 20 remains on the surface of the concrete even after the formwork 10 is demolded. Even if the curing sheet 20 is bag-shaped, it is similarly left. Curing with the curing sheet 20 may be continued for 28 days or longer after the formwork 10 is demolded, or may be continued for 91 days or more after the formwork 10 is demolded. Furthermore, of course, curing may be continued until the concrete structure is handed over (for example, one year or more after demolding). By continuing such long-term curing, the strength and durability of the concrete structure C can be dramatically increased, and the quality thereof can be improved. After curing for a predetermined period of time is completed, the curing sheet 20 is removed from the concrete structure C, and thereby the concrete structure C is completed.

As described above, in the method for manufacturing a concrete structure according to the present embodiment, the shape of the curing sheet 20 is cylindrical or bag-shaped so that when the concrete hardens, the curing sheet 20 can be put over the concrete structure C as it is. there is Therefore, the curing sheet 20 that has been used before concrete is placed can be left on the concrete without using a holding member, an adhesive tape, or the like, so that the curing sheet 20 can be left on the concrete more easily.

In addition, the method for manufacturing a concrete structure according to the present embodiment includes a step of preparing a plurality of forms 10 configured to define a space inside, a step of stacking the plurality of forms 10, and a step of arranging a cylindrical or bag-shaped curing sheet 20 inside the frame 10, and the step of placing a plurality of forms 10 outside the curing sheet 20 so that the curing sheet 20 is formed into a plurality of It is designed to be carried out after being supported by the formwork 10 . Therefore, even if a thin sheet that does not stand on its own is used as the curing sheet 20 , the concrete placed in the curing sheet 20 can be firmly held by the formwork 10 .

In addition, in the method of manufacturing a concrete structure according to the present embodiment, in the step of arranging the formwork, the cross-sectional area along the horizontal direction of the cylindrical or bag-shaped curing sheet 20 is inside the plurality of formwork 10. It can be smaller than the horizontal cross-sectional area of the space to be formed. In this case, it is possible for the curing sheet 20 to extend (spread) slightly outward due to the weight of the cast concrete, thereby preventing the curing sheet 20 in contact with the concrete from being wrinkled. As a result, transfer of wrinkles to the surface of the concrete structure C cured by the curing sheet 20 can be suppressed. The cross-sectional area along the horizontal direction of the curing sheet 20 before pouring concrete is 0.0006% to 0.000% of the cross-sectional area along the horizontal direction of the space formed inside the formwork 10 . It may be as small as 6%. In this case, the performance of the curing sheet 20 can be maintained, and the occurrence of wrinkles due to stretching to some extent can be more suitably prevented.

In addition, the method for manufacturing a concrete structure according to the present embodiment further includes a step of demolding the plurality of forms 10 with the curing sheets 20 adhered to the concrete after the poured concrete has hardened. . Therefore, the curing sheet 20 can be left on the concrete, and the formwork 10 removed from the mold can be used at another site. Each of the plurality of molds is preferably a lightweight mold made of plastic or carbon. In this case, the installation work of the formwork 10 can be easily performed. In addition, a steel formwork may be sufficient as a formwork.

In addition, the method for manufacturing a concrete structure according to this embodiment further includes a step of installing the guide 1 on the base B. You may do so. In this case, the formwork 10 can be aligned and stacked, and the formwork 10 after being stacked can be stabilized.

In addition, in the method for manufacturing a concrete structure according to the present embodiment, in the step of placing concrete, the concrete may be placed in a state in which a predetermined tension is applied to the curing sheet 20 from one end to the opposite side. . In this case, the curing sheet 20 in contact with the concrete can be further prevented from wrinkling, and as a result, the transfer of wrinkles to the surface of the concrete structure C cured by the curing sheet 20 can be suppressed.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments and can be applied to various embodiments. For example, in the above embodiment, the method for manufacturing a concrete structure using the guide 1 and the forms 10, 10a having the through holes 14 has been described, but the present invention is not limited to this. For example, as shown in FIG. 4, each formwork 10b may be provided with a tenon structure, and a formwork in which projections 16 are provided on the upper side and holes (grooves) are provided on the lower side may be used. In this case, there is no need to install the guide 1, and as shown in FIGS. Curing can be performed by placing the curing sheet 20 and placing concrete in it. Other configurations of this manufacturing method are the same as those of the above-described embodiment, and the description thereof is omitted. According to this manufacturing method, the installation work of the guide 1 is not required, and the entire stacking work of the forms 10b can be simplified. It should be noted that the formwork may have the above tenon structure that allows it to be fitted with another formwork in the vertical direction, and may be further provided with through holes 14 so that the formwork can be stacked using the guide 1 .

Further, in the above embodiment, the formwork was used as a member for fixing the lower part of the curing sheet 20, but as shown in FIGS. 5A and 5B, one end (lower end) of the curing sheet 20 A dedicated bolting member 30 may be used. In this case, even when a predetermined tension is applied to pull the wrinkled curing sheet 20 upward, the curing sheet 20 is more reliably prevented from coming off the stopper. FIG. 5(b) shows a case where reinforcing bars S are provided inside, but even in such a case, the curing sheet 20 can be made taut. Moreover, in the above-described embodiment, an example of a method of manufacturing a concrete structure at a construction site has been described, but the present manufacturing method may of course be applied to precasting or the like.

γ_Ｓ：固体の表面張力
γ_Ｌ：液体の表面張力
γ_ＳＬ：固体と液体の界面張力 In the above-described embodiment, the curing sheet 20 is not particularly limited, but it is preferable to adopt a curing sheet 20 whose contact surface on the concrete side has a water contact angle of 50 degrees or more. Specifically, the contact angle θ of the contact surface of the curing sheet 20 with water is preferably 69 degrees or more, more preferably 80 degrees or more, and more preferably 90 degrees or more. It is even more preferable to have Here, the “contact angle θ” is the angle formed by the tangent line of the liquid droplet and the solid surface (the surface of the curing sheet 20), as shown in FIG. is indicated by

γ _S : Surface tension of solid γ _L : Surface tension of liquid γ _SL : Interfacial tension of solid and liquid

The "contact angle θ" can be measured, for example, by the θ/2 method. Specifically, as shown in FIG. 6B, the radius r and height h of the droplet are obtained. Then, the contact angle θ can be obtained from the following formulas (2) and (3).

Normally, when concrete contains excess water beyond the amount required for the initial hardening of cement, breathing water may occur when the concrete hardens after placement. As described above, the use of the curing sheet 20 having a contact angle with water of 50 degrees or more can effectively suppress the generation of breathing water. The reason why the generation of breathing water is suppressed in this way is that if the contact angle (also called the wetting angle) of the sheet surface (contact surface) of the curing sheet 20 covering the concrete surface is large, the amount of water contained in the concrete is large. At the contact surface of the sheet, the water that tries to escape from the surface and the air that exists in the water are pushed back into the concrete. presumed to move forward. Since the curing sheet 20 suppresses the generation of breathing water in this way, the concrete contains the water necessary for the hydration reaction after demolding. It is possible to manufacture a concrete structure capable of exhibiting qualities such as predetermined compressive strength and durability without supplying curing water from the outside or using curing water so much.

The curing sheet 20 preferably has a low water vapor permeability, preferably a sheet with a water vapor permeability of 10 g/m ² ·24 h or less, and a sheet with a water vapor permeability of 5 g/m ² . - It is much more preferable that it is 24 hours or less. In addition, the curing sheet 20 preferably uses a sheet with a low carbon dioxide permeability, and preferably has a carbon dioxide permeability of 100,000 cc/m ² · 24 h · atm or less. More preferably, the permeability is 50,000 cc/m ² ·24 h·atm or less. By processing the surface of the material by various surface processing techniques, a sheet with reduced water vapor permeability or carbon dioxide permeability can be produced.

10, 10a, 10b... formwork, 12, 12a to 12d... frame body, 14... through hole, 20... curing sheet, 22... body portion, 24... lower tab, 26... upper tab, 30... bolting member, B ... base, C ... concrete structure.

Claims (8)

providing a plurality of formwork configured to define a space therein;
A step of preparing a cylindrical or bag-shaped curing sheet;
A step of stacking the plurality of molds and arranging the cylindrical or bag-shaped curing sheet inside the stacked molds;
a step of fixing one end of the curing sheet to a base;
placing concrete inside the curing sheet after fixing the one end;
After the cast concrete has hardened, curing the hardened concrete with the curing sheet as it is,
In the arranging step, a gap is formed between the inner peripheral surface of the mold and the outer peripheral surface of the curing sheet,
The step of placing is performed after the plurality of forms are arranged outside the curing sheet and the curing sheet is supported by the plurality of forms,
The cross-sectional area along the horizontal direction in the outer shape of the curing sheet before placing the concrete is 0.0006% to 0 with respect to the cross-sectional area along the horizontal direction of the space formed inside the formwork. as small as .6%,
A method of making a concrete structure. Further comprising a step of demolding the plurality of formwork with the curing sheet attached to the concrete after the cast concrete has hardened,
A method for manufacturing a concrete structure according to claim 1. The plurality of forms are lightweight forms made of plastic or carbon,
A method for manufacturing a concrete structure according to claim 1 or 2. further comprising the step of installing a guide with respect to the base;
Stacking the formwork by passing the guide through a through hole provided in the formwork;
A method for manufacturing a concrete structure according to any one of claims 1 to 3. The formwork has a configuration that can be fitted with another formwork in the vertical direction,
In the arranging step, the formwork is stacked using the configuration,
A method for manufacturing a concrete structure according to any one of claims 1 to 4. In the step of placing the concrete, the concrete is placed while a predetermined tension is applied to the curing sheet from the one end toward the opposite side.
A method for manufacturing a concrete structure according to any one of claims 1 to 5. The curing sheet is a non-self-supporting sheet having a thickness of 0.02 mm to 0.2 mm.
A method for manufacturing a concrete structure according to any one of claims 1 to 6. providing a plurality of formwork configured to define a space therein;
A step of preparing a cylindrical or bag-shaped curing sheet;
A step of stacking the plurality of molds and arranging the cylindrical or bag-shaped curing sheet inside the stacked molds;
a step of fixing one end of the curing sheet to a base;
placing concrete inside the curing sheet after fixing the one end;
After the cast concrete has hardened, curing the hardened concrete with the curing sheet as it is,
The step of placing is performed after the plurality of forms are arranged outside the curing sheet and the curing sheet is supported by the plurality of forms,
At least one tab is provided on at least the one end of the curing sheet, and in the fixing step, the tab is sandwiched between the first stage mold among the plurality of molds and the base. The one end of the curing sheet is fixed to the base by
A method of making a concrete structure.

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