JP6800076B2 - How to select fixing tape and how to manufacture concrete structure - Google Patents

Description

The present invention relates to a method for selecting a fixing tape for fixing a curing sheet to a formwork, and a method for manufacturing a concrete structure (construction method) using the tape selected by the selection method.

As a construction method for constructing a concrete structure such as a bridge or a dam, the construction method described in Patent Document 1 has been newly used. In the construction method described in Patent Document 1, a formwork for placing concrete is installed, and concrete is placed in a state where a non-permeable curing sheet is fixed in advance on the inner surface of the formwork. Then, although the formwork is removed after the concrete is placed, the curing sheet is left on the concrete side, the placed concrete is covered with this curing sheet as it is, and the concrete is cured for a long period of time.

According to the construction method described in Patent Document 1, by using a non-permeable curing sheet having a contact angle with water of 50 degrees or more at the time of placing, breathing that normally occurs when concrete C is hardened after placing. The generation of water and bubbles can be significantly suppressed, and the state in which concrete C contains the water required for the hydration reaction after demolding is maintained from casting to demolding and curing. It becomes possible to do. As a result, according to this construction method, a concrete structure C having improved compressive strength, durability or surface aesthetics can be obtained without supplying curing water from the outside or using curing water so much during concrete curing. be able to.

Japanese Patent No. 5688429

In the construction method of Patent Document 1, as described above, it is possible to manufacture (construct, etc.) a concrete structure in which the compressive strength, durability, or surface aesthetics are significantly improved as compared with the conventional construction method. Sometimes it is necessary to ensure that the curing sheet is left on the concrete side. As one of the remaining methods, according to the examination by the applicants, the curing sheet is attached to the inner surface of the mold by attaching the double-sided adhesive tape so as to straddle the edge of the curing sheet and the mold. A method of fixing is being studied. According to this method, the curing sheet can be left on the concrete by the double-sided adhesive tape when the formwork is removed. However, there is a possibility that a part of the curing sheet may be peeled off depending on the method of removing the mold, so it is desired to develop a method that can more reliably leave the curing sheet on the concrete.

The present invention has been made to solve the above-mentioned problems, and a method for selecting a fixing tape capable of reliably leaving a curing sheet on the concrete side when the formwork is removed, and the present invention. It is an object of the present invention to provide a method for manufacturing a concrete structure using a fixing tape selected by a selection method.

In order to solve the above problems, the present inventors, in the process of repeated diligent studies, when the curing sheet is fixed to the mold using the double-sided adhesive tape, the adhesive surface on the opposite side to the mold side (the first in FIG. 4). It was noticed that the adhesive layer (see 30a) tends to adhere to the concrete surface. As a result of further studies, the present inventors have found that the adhesive strength of the double-sided adhesive tape to concrete correlates with the strength of the cast concrete, and by using the concrete strength as an index, the cast The present invention has been completed based on the finding that the residual strength of the curing sheet on concrete can be increased.

That is, in the method of selecting the fixing tape according to the present invention, concrete is placed after fixing the curing sheet to the mold with the double-sided adhesive tape, and when the mold is removed, the curing sheet is covered with the double-sided adhesive tape. It is a method for selecting the double-sided adhesive tape to be used in the method of curing by leaving it on concrete, and it is a step to calculate the peeling force required to peel the double-sided adhesive tape and the curing sheet from the mold. , The step of calculating the residual force required to leave the double-sided adhesive tape and the curing sheet on the concrete, and the step of selecting the double-sided adhesive tape whose residual force is larger than the peeling force. , It is a value calculated based on the concrete strength of the concrete to be cast.

This method of selecting the fixing tape includes a step of selecting the double-sided adhesive tape so that the residual force for leaving the curing sheet or the like on the concrete is larger than the peeling force for peeling the curing sheet or the like from the mold. This residual force is calculated based on the concrete strength of the cast concrete. According to the study by the present inventors, it has been found that the adhesive strength of the concrete to which the double-sided adhesive tape is attached tends to increase as the strength of the concrete increases. By selecting the double-sided adhesive tape so that the residual force calculated based on the strength is larger than the peeling force, the curing sheet can be more reliably placed on the surface of the cast concrete when constructing an actual concrete structure. It is possible to leave it behind.

In addition, the present invention relates to a method for manufacturing a concrete structure as another aspect, and this manufacturing method includes an installation process for installing a formwork for placing concrete and a double-sided adhesive tape at the end and mold of the curing sheet. A fixing process of fixing the curing sheet to the inner surface of the formwork by pasting it so as to straddle the frame, and placing concrete while the curing sheet is fixed to the formwork with double-sided adhesive tape. It includes a step, a demolding step of removing the formwork after placing the concrete, and a curing step of leaving the curing sheet on the surface of the concrete and curing the concrete for a predetermined period after the demolding step. Then, in the manufacturing method (construction method) of this concrete structure, the tape selected by the above-mentioned selection method is used as a double-sided adhesive tape for fixing the curing sheet, whereby the curing sheet is surely left on the concrete. It becomes possible to improve the compressive strength, durability or surface aesthetics of the concrete structure to be constructed.

In the above method for selecting the fixing tape, the residual force is preferably a value calculated based on the environmental temperature of the concrete to be cast. The residual force required to leave the double-sided adhesive tape and curing sheet on the concrete has a strong correlation with the concrete strength, but in addition to this, the environmental temperature of the concrete to be cast (when cast). According to the study by the present inventors, it has become clear that there is a correlation with the temperature and the integrated time (integrated temperature) at that temperature. Therefore, by calculating the residual force including the environmental temperature of concrete in addition to the concrete strength, it is possible to select a fixing tape (double-sided adhesive tape) that can realize more reliable residual, and described above. A suitable double-sided adhesive tape can be selected according to the manufacturing method. The "environmental temperature" is the temperature in the process of hardening the cast concrete.

Further, in the above method for selecting the fixing tape, the peeling force preferably includes the adhesive force between the mold and the curing sheet. Generally, the adhesive strength between the mold and the curing sheet is not so strong, but by selecting the fixing tape including this adhesive strength, more reliable leaving can be realized. It is possible to select a fixing tape.

Further, in the above method for selecting the fixing tape, the adhesive width of the double-sided adhesive tape to the concrete may be larger than the adhesive width of the double-sided adhesive tape to the formwork. In this case, it becomes possible to select a double-sided adhesive tape that can more reliably realize the remaining of the curing sheet on the concrete surface by the double-sided adhesive tape.

In the method for manufacturing a concrete structure using the fixing tape selected by the above-mentioned fixing tape selection method, the adhesive width of the double-sided adhesive tape to the outer edge of the mold may be 7 mm or less, and double-sided adhesive The adhesive width of the tape to concrete may be 7 mm or more. Further, the thickness of the base material of the double-sided adhesive tape may be thinner than 1.0 mm. In this case, it is possible to prevent the traces of the double-sided adhesive tape from remaining on the concrete surface, further enhancing the aesthetic appearance of the concrete surface. , Can be improved.

According to the present invention, a fixing tape selection method capable of reliably leaving the curing sheet on the concrete side when the formwork is removed, and concrete using the fixing tape selected by the selection method. A method of manufacturing a structure can be provided.

FIG. 1 is a flowchart showing an outline of a method for manufacturing a concrete structure according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an outline of a method for manufacturing a concrete structure according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a state in which the curing sheet is fixed to the mold with the double-sided adhesive tape. FIG. 4 is a schematic partial cross-sectional view showing a part of a state in which concrete is cast on a curing sheet fixed to a mold with double-sided adhesive tape. FIG. 5 is a table showing the adhesive strength A between various double-sided adhesive tapes and concrete. FIG. 6 is a graph showing the relationship between the adhesive strength A (measured value) shown in FIG. 5 and the adhesive strength (catalog value) of the double-sided adhesive tape. FIG. 7 is a table showing the adhesive strength B between various double-sided adhesive tapes and the mold. FIG. 8 is a graph showing the relationship between the adhesive strength B (measured value) shown in FIG. 7 and the adhesive strength (catalog value) of the double-sided adhesive tape. FIG. 9 is a graph showing an example of calculating the peeling force FK and the residual force FC by the selection method according to the present embodiment. FIG. 10 is a table showing that the peeling force FK and the residual force FC fluctuate depending on the selection method according to the present embodiment when the concrete strength is changed. FIG. 11 is a table showing the relationship between the calculated values shown in FIG. 10 and a case in which the calculated values could not be actually left. FIG. 12 is a schematic view showing the contact angle of the surface of the curing sheet used in the present production method with water.

Hereinafter, a method for selecting a fixing tape according to the present invention and a method for manufacturing a concrete structure using the fixing tape selected by the selection method 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 function, and duplicate description will be omitted.

First, the curing sheet is fixed to the mold using the double-sided adhesive tape selected by the method for selecting the fixing tape according to the present invention, and then concrete is placed, and the double-sided adhesive tape is used when the mold is removed. The outline of the method of curing by leaving the curing sheet on the concrete will be described with reference to FIGS. 1 and 2. FIG. 1 is a flowchart showing an outline of a method for manufacturing a concrete structure according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an outline of a method for manufacturing a concrete structure according to an embodiment of the present invention. Is.

As shown in FIG. 1, the method for manufacturing a concrete structure according to the present embodiment includes a preparatory step (step S1) for preparing a formwork for placing concrete, a curing sheet and a double-sided adhesive tape, and installation of the formwork. Step (step S2), placing concrete with the curing sheet fixed (arranged) on the inner surface of the formwork with double-sided adhesive tape (step S3), removing the formwork after placing the concrete. The demolding step (step S4) includes a curing step (step S5) in which the curing sheet is left on the concrete surface with a double-sided adhesive tape after the demolding step, and the concrete is cured for a predetermined period.

In the preparation step of step S1, first, as shown in FIG. 2A, the formwork 10, the curing sheet 20, and the double-sided adhesive tape 30 to be used when manufacturing the concrete structure are prepared. The double-sided adhesive tape 30 prepared here is a tape having a predetermined adhesive strength selected by a selection method described later. When manufacturing a general concrete structure, a large number of formwork and curing sheets are usually used, but in this embodiment, a set of formwork 10 and curing sheet 20 is used for easy explanation. The case will be described as an example. However, the same applies when two or more sets of formwork 10 and curing sheet 20 are used.

The curing sheet 20 used in the present embodiment is, for example, a rectangular sheet in a plan view, has substantially the same width (slightly small) as the surface (inner surface 12) of the mold 10, and has a size of about 0.02 mm to 2.0 mm. Has a thickness. As the curing sheet 20, it is preferable to use a thermoplastic resin sheet, and examples of the thermoplastic resin used here include low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and olefin-based thermoplastic elastomer. Olefin-based resins such as; polyamide; polyethylene terephthalate; polycarbonate; polyvinyl chloride, chlorinated polyvinyl chloride, polyvinyl chloride-based resins such as polyvinylidene chloride; fluororesins and the like. As the curing sheet 20, it is preferable to use an olefin-based thermoplastic elastomer. The olefin-based thermoplastic elastomer is an ethylene-propylene copolymer or a melt mixture or polymerization reaction product of polypropylene and ethylene-propylene rubber. For example, "Prime TPO (registered trademark)" manufactured by Prime Polymer Corporation, Japan Polypropylene Corporation Examples include "Newcon (registered trademark)" manufactured by the company, "Cataloy" manufactured by Sun Aroma Co., Ltd., and "Zeras (registered trademark)" manufactured by Mitsubishi Chemical Corporation.

In the preparatory step, the curing sheet 20 is arranged on the inner surface 12 (the surface of the formwork 10 on the concrete casting side) side of the formwork 10, and then the double-sided adhesive tape 30 is placed on the end (outer edge) of the formwork 20 and the formwork. The curing sheet 20 is fixed to the mold 10 by sticking it so as to straddle the outer edge of the 10. At this time, it is preferable to attach the double-sided adhesive tape 30 to the curing sheet 20 along four sides of the outer edge of the curing sheet 20 or at least two sides of the upper and lower ends. One inner surface 22 of the curing sheet 20 is the surface of the curing sheet 20 on the concrete casting side.

When the preparation for the installation of the mold 10, the curing sheet 20 and the double-sided adhesive tape 30 is completed, the process proceeds to the step S2 mold installation step as shown in FIG. The fixed formwork 10 is installed at a predetermined position. The mold 10 may be installed in a state where the curing sheet 20 is fixed to the inner surface 12 side of the mold 10 by the double-sided adhesive tape 30 in this way, or conversely, the mold 10 is installed at a predetermined position. Later, in the same manner as described above, the curing sheet 20 may be fixed to the inner surface 12 side of the mold 10 with the double-sided adhesive tape 30.

Subsequently, the process proceeds to the casting step of step S3, and as shown in FIG. 2C, the curing sheet 20 is fixed to the inner surface 12 of the mold 10 and further along the outer edge of the inner surface 22 of the curing sheet 20. Concrete C is placed with the double-sided adhesive tape 30 attached. After that, when the compaction of the concrete is completed, the concrete C is cured for, for example, about 3 to 28 days with the formwork 10 fitted to promote the hydration reaction of the concrete. The condition is maintained until the curing of concrete C is completed.

Subsequently, when the concrete placing and curing thereof in the placing step are completed, the process proceeds to the removing step of removing the formwork in step S4, and as shown in FIG. 2D, the hardened concrete C The mold 10 is removed from the mold 10 while leaving the surface covered with the curing sheet 20, and is separated from the concrete C. At this time, since the double-sided adhesive tape 30 prepared in the preparation step is selected by a predetermined selection method, the peeling force FK required for the curing sheet 20 and the double-sided adhesive tape 30 to be peeled from the mold 10. Since the residual force FC required to maintain the state in which the curing sheet 20 and the double-sided adhesive tape 30 are adhered to the concrete C is stronger than that, the mold 10 is removed. At that time, the curing sheet 20 is surely left on the surface of the concrete C by the double-sided adhesive tape 30.

Subsequently, after the mold 10 is removed from the mold, the process proceeds to the curing step of step S5, and the concrete C is cured for a predetermined period using the curing sheet 20 left on the sticking surface of the concrete C with the double-sided adhesive tape 30. The curing by the curing sheet 20 may be continued for 28 days or more after the mold 10 is removed, or may be continued for 91 days or more after the mold 10 is removed. Further, of course, curing may be continued until the concrete structure is delivered (for example, one year or more after demolding). By continuing such long-term curing, the strength and durability of concrete C can be dramatically increased, and the quality thereof can be improved. When the curing for the predetermined period is completed, as shown in FIG. 2 (e), the curing sheet 20 is removed from the concrete structure CS together with the double-sided adhesive tape 30, whereby the concrete structure CS is completed.

Here, with reference to FIGS. 3 and 4, a method for selecting the double-sided adhesive tape 30 which is a fixing tape used in this method will be described. FIG. 3 is a schematic cross-sectional view showing a state in which the curing sheet is fixed to the mold with the double-sided adhesive tape. FIG. 4 is a schematic partial cross-sectional view showing a state in which concrete is cast on a curing sheet fixed to a mold with double-sided adhesive tape.

As shown in FIG. 3, in this method, the double-sided adhesive tape 30 is first attached so as to straddle the outer edge of the curing sheet 20 and the outer edge of the mold 10, whereby the curing sheet 20 is attached to the mold 10. Fixed to. Then, the concrete C is placed using the formwork 10 to which the curing sheet 20 is fixed in this way. As shown in FIG. 3, the double-sided adhesive tape 30 is arranged between, for example, the first adhesive layer 30a on the concrete C side, the second adhesive layer 30b on the formwork 10 side, and the first and second adhesive layers 30a and 30b. Although it is composed of the base material 30c to be formed, it may be configured without a base material. Further, the base material 30c may be made of a non-woven fabric or a synthetic resin film (for example, a polyester film). It should be noted that FIG. 4 is a diagram showing an adhesive state and an adhesive force between the members in a state where concrete is cast and hardened.

As shown in FIG. 4, the adhesive force of the double-sided adhesive tape 30 to the concrete C is A (N / mm) for the adhesive force of the first adhesive layer 30a of the double-sided adhesive tape 30, its width is d ₁ , and its length. Assuming that (the length in the orthogonal direction in the drawing) is L, it can be expressed as "Ad ₁ L". Further, if the adhesive force of the curing sheet 20 to concrete is C (N / mm) and its contact area S ₁ (excluding the area of the double-sided adhesive tape 30), it can be expressed as “CS ₁ ”. Therefore, the residual force FC (N) of the curing sheet 20, which is the adhesive force on the concrete surface side, can be expressed by the following formula (1).
Adhesive force to the concrete surface side (residual force FC) = Ad ₁ L + CS ₁ ... (1)

On the other hand, adhesion to the mold 10, the adhesion to the mold 10 by the second adhesive layer 30b of the double-sided adhesive tape 30 B (N / mm), the width _{d 2,} when the length is L , "Bd ₂ L". Further, if the adhesive force of the curing sheet 20 to the mold 10 is D (N / mm) and its area S ₂ (S ₁ <S ₂ ), it can be expressed as “DS ₂ ”. Therefore, the peeling force FK (N) of the curing sheet 20, which is the adhesive force on the mold side, can be expressed by the following formula (2).
Adhesion to the mold side (peeling force FK) = Bd ₂ L + DS ... (2)

Then, in order to leave the curing sheet 20 on the concrete side with the double-sided adhesive tape 30 or the like when the mold 10 is removed from the concrete, the residual force FC and the peeling force FK of the curing sheet 20 described above have the following relationship. Must be met.
Residual force FC> Peeling force FK ・ ・ ・ (3)

By the way, according to the study by the present inventors, the adhesive strength of the double-sided adhesive tape 30 for leaving the curing sheet 20 on the concrete to the concrete is the catalog value of the adhesive strength specified in the general adhesive tape (against stainless steel). ) Can not be applied as it is. That is, according to the study by the present inventors, as shown in the table of FIG. 5, the strength of the concrete to be attached (when the formwork is removed), the environmental temperature of the cast concrete, and the integrated temperature thereof (environmental temperature). × It has been found that the temperature changes (increases or decreases) depending on the time (from casting to demolding). According to the study by the present inventors, this is because the strength of the concrete is increased and the tensile strength of the concrete surface portion to which the double-sided adhesive tape is attached is also increased, so that the concrete surface portion is less likely to be destroyed when the tape is peeled off. It is presumed that this is because of this. Therefore, as shown below, the present inventors completed the present invention by performing the following evaluations in order to more reliably leave the curing sheet 20 on the concrete C using the double-sided adhesive tape 30.

[Adhesive strength A between concrete and double-sided adhesive tape (remaining tape)]
First, the present inventors change the types of commercially available double-sided adhesive tapes (adhesive strength catalog value (against stainless steel)), the strength of concrete to be attached, and conditions such as environmental temperature and integrated temperature. In accordance with "JIS Z 0237: 2009 Adhesive Tape / Adhesive Sheet Test Method", the actual adhesive strength A (peeling strength / measured value (N / mm)) to concrete was actually measured and summarized in the table of FIG. The double-sided adhesive tapes No. 1 to No. 3, No. 5 and No. 7 to 11 described in the types of tapes used here (FIG. 5) are tapes manufactured by Teraoka Seisakusho Co., Ltd. The double-sided adhesive tapes of No. 4 and No. 12 to 21 were tapes manufactured by Nitto Denko Co., Ltd., and the tapes of No. 6 were tapes manufactured by Nitto Denko CS System Co., Ltd. In addition, these peeling tests were performed. From the conditions and results of the above, the theoretical value (adhesive strength A) of peeling with concrete was calculated from the catalog value of the adhesive strength of the double-sided adhesive tape (against stainless steel) using the multiple regression equation. Shown in 6. Then, the relationship between the catalog value (against stainless steel) of the double-sided adhesive tape shown in FIG. The adhesive strength A of the above was approximated as the following formula (4).
^{A = 0.903-2.65 × 10 -2 × a} -4.54 × 10 -5 × b
+3.36 × 10 ^-2 × c-2.68 × 10 ^-1 × d ... (4)
Here, "a" indicates the environmental temperature (° C.), "b" indicates the integrated temperature (time / ° C.), "c" indicates the estimated concrete strength (N / mm ² ), and "d" indicates both sides. The catalog value (N / mm) of the adhesive strength of the adhesive tape is shown. The "environmental temperature" is the temperature in the process of hardening the cast concrete, and the "integrated temperature" is a value obtained by multiplying the environmental temperature by the hardening time of the concrete.

[Adhesive strength B between formwork and double-sided adhesive tape (remaining tape)]
Further, the adhesive strength B between the mold and the double-sided adhesive tape was also measured in the same manner as described above. The table of FIG. 7 shows the peeling test results of the mold and the double-sided adhesive tape. It was confirmed that the adhesive strength of the double-sided adhesive tape to the mold is not the same as the catalog value, but shows the same tendency. No. 1 described in the type of tape used here (FIG. 7). 1 and No. The double-sided adhesive tapes 10 to 15 are tapes manufactured by Nitto Denko KK, and No. 2-No. 5 and No. 7 to No. The double-sided adhesive tape of No. 9 is a tape manufactured by Teraoka Seisakusho Co., Ltd. The tape of No. 6 was a tape manufactured by Nitto Denko CS System Co., Ltd. Further, in the same manner as above, the theoretical value of the adhesive force to the mold (adhesive force B) is obtained from the catalog value of the adhesive force of the double-sided adhesive tape (against stainless steel) by the multiple regression analysis from the numerical values shown in the table of FIG. Calculated. This relationship is shown in FIG. Then, the relationship between the catalog value (against stainless steel) of the double-sided adhesive tape shown in FIG. 8 and the adhesive force to the mold (actual measurement) is summarized in an equation, and the adhesive force B of the double-sided adhesive tape to the mold is expressed by the following equation (measurement). It was approximated as 5).
B = 0.211 + 0.780 × d ・ ・ ・ (5)
Here, "d" indicates a catalog value (N / mm) of the adhesive strength of the double-sided adhesive tape. In the above equation, the environmental temperature and the tape width were all set to constant values, so they are excluded from the multiple regression analysis.

[Adhesive strength between curing sheet and concrete C]
Since the adhesive force between the curing sheet and concrete is not usually generated, the subsequent calculation is performed assuming that it is zero in this embodiment. However, the adhesive strength C may be determined and calculated.

[Adhesive strength D between curing sheet and formwork]
The adhesive strength D between the curing sheet and the mold can be used as an actually measured value, for example, the following value as a reference value.
D (N / mm) = 350 (g) x 9.8 (m / s ² ) / 30 (mm) x 1000 (mm) ... (6)
The above reference value 350 (g) is an example, and different values can be adopted depending on the type of curing sheet.

Next, the "peeling force FK" required for peeling the double-sided adhesive tape and the curing sheet from the mold is calculated based on the measured values or theoretical values (calculated values) of the above-mentioned adhesive forces A to D. At the same time, the "residual force FC" required to leave the double-sided adhesive tape and the curing sheet on the concrete is calculated. Then, one of the double-sided adhesive tapes is selected from, for example, the table of FIG. 5 so that the residual force FC calculated in consideration of the relationship with the strength of the concrete to be cast is larger than the peeling force FK. To do.

FIG. 9 is a table showing an example of such a selection method. A preferable double-sided adhesive tape may be selected each time based on the above-mentioned equations (1) to (6), or as shown in FIG. 9, each input item on the left side (adhesive strength catalog value or tape). Enter predetermined values in (width, etc.), insert those values into the above-mentioned formulas (1) to (6), and perform computer processing or the like to obtain the respective adhesive strengths A, B (N / mm) and peeling strength FK ( N), the residual force FC (N), and the magnitude relationship between the peeling force FK and the residual force FC may be automatically calculated on the right side of the table. Such computer processing can be executed by an information processing device such as a personal computer. In addition, you may calculate using only a part of computer processing. Then, a double-sided adhesive tape having a residual force FC larger than the peeling force FK is selected according to the strength (calculated value) of the concrete to be cast, and is used to construct the concrete structure described above. By performing the above, the curing sheet installed before the concrete is placed is surely left on the surface of the concrete, and long-term curing can be carried out more reliably.

Further, the present inventors examined the relationship between the concrete strength and the peeling force FK / residual force FC and the like in more detail, and summarized them as shown in FIG. In FIG. 10, even when the same double-sided adhesive tape (cases No. 1 to No. 7, No. 8 to No. 14, No. 15 to No. 19) is used, the concrete strength to be cast is shown. It has been shown that the adhesive strength A and the residual strength FC change depending on (at the time of demolding), and the theoretical residual strength is determined. That is, the strength of the concrete to be cast (when the formwork is removed) is obtained in advance by calculation, and the residual force FC or the like is calculated based on the calculated concrete strengths (1) to (6). Then, by selecting the double-sided adhesive tape so that the residual force FC is larger than the peeling force FK, when the mold 10 is removed from the concrete after the concrete is cast and hardened, the curing sheet 20 is twisted. It can be reliably left on the concrete surface, and the compressive strength, durability or surface aesthetics of the concrete structure can be improved. Judgment A in FIG. 10 shows a case where the residual force FC is larger than the peeling force FK, and judgment B shows a case where the residual force FC becomes smaller than the peeling force FK. Note that FIG. 11 shows the calculated values shown in FIG. 10 and an example in which they could not be actually left. As is clear from FIG. 11, it was confirmed that those judged to be OK (judgment A) in the calculated value are surely left behind even when they are actually attached to concrete. In other words, it was confirmed that by using this determination method, it is possible to more reliably leave the curing sheet on the concrete side at the actual construction site.

As described above, in the method for selecting the fixing tape according to the present embodiment, the residual force FC for leaving the curing sheet 20 or the like on the concrete C is larger than the peeling force FK for peeling the curing sheet 20 or the like from the mold 10. A step of selecting the double-sided adhesive tape 30 is provided so that the residual force FC is calculated based on the concrete strength of the cast concrete C. According to the study by the present inventors, as described above, the adhesive strength of the concrete C to which the double-sided adhesive tape 30 is attached tends to increase as the strength of the concrete C increases. By selecting the double-sided adhesive tape 30 so that the residual force FC calculated by the above is larger than the peeling force FK, the curing sheet 20 is more reliably placed on the surface of the concrete when constructing an actual concrete structure. It is possible to leave it in.

Further, by installing the mold 10 for concrete placement and attaching the double-sided adhesive tape 30 so as to straddle the end of the curing sheet 20 and the mold 10, the inner surface of the mold 10 is covered. A fixing step of fixing the curing sheet 20, a placing step of placing concrete C in a state where the curing sheet 20 is fixed to the formwork 10 by a double-sided adhesive tape 30, and removing the formwork 10 after placing the concrete. The method (construction method) for manufacturing a concrete structure including a mold removing step and a curing step in which the curing sheet 20 is left on the surface of the concrete C after the mold removing step to cure the concrete C for a predetermined period is described above. By using the tape selected by the selection method as the double-sided adhesive tape 30 for fixing the curing sheet 20, the curing sheet 20 is surely left in the concrete C, and the concrete structure to be constructed is compressed. It can improve strength, durability or surface aesthetics.

Further, in this method of selecting the fixing tape, the residual force FC is a value calculated based on the environmental temperature of the concrete C to be cast. The residual force FC required to leave the double-sided adhesive tape 30 and the curing sheet 20 on the concrete C has a strong correlation with the concrete strength, but in addition to this, the environmental temperature of the concrete C to be cast (casting). It has been found that there is a correlation with the temperature at the time of installation and the integrated time (integrated temperature) at that temperature. Therefore, by calculating the residual force FC including the environmental temperature of concrete in addition to the concrete strength, it is possible to select a fixing tape (double-sided adhesive tape) that can realize more reliable residual. ..

Further, in this method of selecting the fixing tape, the peeling force FK is calculated including the adhesive force between the mold 10 and the curing sheet 20. Generally, the adhesive force between the mold 10 and the curing sheet 20 is not so strong, but since it exists to some extent, it is more reliable by selecting the fixing tape including this adhesive force. It is possible to select a fixing tape that can realize a good residual.

Further, in this method of selecting the fixing tape, the adhesive width d ₁ of the double-sided adhesive tape 30 to the concrete C may be larger than the adhesive width d _{2 of the} double-sided adhesive tape 30 to the mold 10. In this case, it is possible to select a double-sided adhesive tape that can more reliably realize the remaining of the curing sheet 20 on the concrete surface by the double-sided adhesive tape 30.

In the method for manufacturing a concrete structure using the fixing tape selected by the above-mentioned fixing tape selection method, as an example, the adhesive width d ₂ of the double-sided adhesive tape 30 to the outer edge of the formwork 10 is 7 mm or less. The adhesive width d ₁ of the double-sided adhesive tape 30 to the concrete C may be 7 mm or more. As described above, the adhesive width d ₁ of the double-sided adhesive tape 30 to the concrete C is equal to or wider than the adhesive width d _{2 of the} double-sided adhesive tape 30 to the outer edge of the mold 10, so that the concrete of the curing sheet 20 is formed. It is possible to more reliably realize the leaving in the concrete.

Further, the thickness of the base material 30c of the double-sided adhesive tape 30 may be thinner than 1.0 mm. In this case, it is possible to prevent the traces of the double-sided adhesive tape 30 from remaining on the concrete surface, and further improve the aesthetic appearance of the concrete surface.

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 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 curing sheet 20 is not particularly limited in the above, but it is preferable to use a curing sheet 20 having a contact angle of the contact surface on the concrete C side of the curing sheet 20 with water 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 the contact angle θ is 80 degrees or more, and the contact angle θ is 90 degrees or more. It is even more preferable to have. Here, the "contact angle θ" is an angle formed by the tangent line of the droplet and the solid surface (the surface of the curing sheet 20) as shown in FIG. 12A, and the following equation (7) Indicated by.

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

Then, the "contact angle θ" can be measured by, for example, the θ / 2 method. Specifically, as shown in FIG. 12B, the radius r and the height h of the droplet are obtained. Then, the contact angle θ can be obtained from the following equations (8) and (9).

Generally, if the concrete C contains excess water in excess of the amount required for the initial hardening of the cement, breathing water may be generated when the concrete C is hardened after casting. As described above, by using the curing sheet 20 having a contact angle with water of 50 degrees or more at the time of placing, it is possible to effectively suppress the generation of breathing water. The reason why the generation of breathing water is suppressed in this way is that when the contact angle (also called the wet angle) of the sheet surface (contact surface) of the curing sheet 20 covering the surface of the concrete C is large, it is included in the concrete C. The action of pushing the water that is about to come out from the surface and the air that exists in the water back into the concrete C at the sheet contact surface works, and as a result, the water and the air inside it remain in the concrete C. It is thought that this is because the curing progresses as it is. Then, according to the curing sheet 20, since the generation of breathing water is suppressed in this way, the concrete C contains water necessary for the hydration reaction after demolding, and the concrete curing It is possible to produce a concrete structure capable of exhibiting quality such as predetermined compressive strength and durability without supplying curing water from the outside or using curing water so much.

Also, curing the sheet 20, it is preferable to use a small water vapor permeability of the sheet, it is preferable that the water vapor permeability of the sheet is not more than 10g / m 2 · ^24h, water vapor permeability is 5 g / m ² of sheet -It is even more preferable that it is 24 hours or less. Also, curing the sheet 20, it is preferable to use a small carbon dioxide permeable sheet, it is preferable that the carbon dioxide permeability of the sheet is less 100,000 ^{cc / m 2 · 24h · atm} , sheets of carbon dioxide and even more preferably permeability is less than 50,000 ^{cc / m 2 · 24h · atm} . By processing the surface of the material by various surface processing techniques, it is possible to produce a sheet having reduced water vapor permeability or carbon dioxide permeability.

10 ... formwork, 12 ... inner surface, 20 ... curing sheet, 30 ... double-sided adhesive tape, 30a ... first adhesive layer, 30b ... second adhesive layer, 30c ... base material, C ... concrete, CS ... concrete structure.

Claims (7)

It is used in a construction method in which concrete is placed after fixing the curing sheet to the formwork with double-sided adhesive tape, and the curing sheet is left on the concrete with the double-sided adhesive tape when the formwork is removed. This is a selection method for selecting the double-sided adhesive tape.
A step of calculating the peeling force required to peel the double-sided adhesive tape and the curing sheet from the mold, and
A step of calculating the residual force required to leave the double-sided adhesive tape and the curing sheet on the concrete, and
The step of selecting the double-sided adhesive tape in which the residual force is larger than the peeling force is provided.
The residual force is a value calculated based on the concrete strength of the concrete to be cast, and is a method for selecting a fixing tape. The method for selecting a fixing tape according to claim 1, wherein the residual force is a value further calculated based on the environmental temperature of the concrete to be cast. The method for selecting a fixing tape according to claim 1 or 2, wherein the peeling force includes an adhesive force between the mold and the curing sheet. The method for selecting a fixing tape according to any one of claims 1 to 3, wherein the adhesive width of the double-sided adhesive tape to the concrete is larger than the adhesive width of the double-sided adhesive tape to the mold. Installation process to install formwork for concrete placement and
A fixing step of fixing the curing sheet to the mold by attaching the double-sided adhesive tape so as to straddle the end of the curing sheet and the mold.
A casting step of placing concrete in a state where the curing sheet is fixed to the formwork by the double-sided adhesive tape, and
A demolding step of demolding the formwork after placing the concrete,
A curing step is provided in which the curing sheet is left on the surface of the concrete after the demolding step to cure the concrete for a predetermined period of time.
A method for manufacturing a concrete structure, wherein the double-sided adhesive tape for fixing the curing sheet is a tape selected by the method for selecting a fixing tape according to any one of claims 1 to 4. The method for manufacturing a concrete structure according to claim 5, wherein the adhesive width of the double-sided adhesive tape to the outer edge of the formwork is 7 mm or less, and the adhesive width of the double-sided adhesive tape to the concrete is 7 mm or more. The method for manufacturing a concrete structure according to claim 5 or 6, wherein the thickness of the base material of the double-sided adhesive tape is thinner than 1.0 mm.

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