JP5684417B1 - Method for manufacturing concrete structure - Google Patents

Abstract

The present invention provides a method for producing concrete that can easily realize improvement in productivity by effectively utilizing moisture in the concrete. A method for manufacturing a concrete structure includes an adhesive selection step ST10 for predetermining an optimum concentration range of a water-soluble adhesive in an adhesive composition before a curing sheet sticking step ST20. The adhesive selection step ST10 includes a first process for determining a concentration range necessary for maintaining a minimum contact area ratio indicating an effective adhesion state between the mold 30 and the curing sheet 10, and the curing sheet 10. A second process for determining a concentration range necessary for maintaining a minimum remaining area ratio indicating an effective adhesion state with a concrete structure; a contact area ratio equal to or greater than the minimum contact area ratio; A method of manufacturing a concrete structure comprising: a third treatment for determining a concentration range of the water-soluble adhesive in a region that is equal to or greater than the minimum remaining area ratio as an optimum concentration range. [Selection] Figure 3

Description

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

  In order to manufacture a concrete structure, concrete is placed in a mold placed at a predetermined position, and after the setting has progressed to some extent and hardened, the mold is removed from the mold, and the mold is removed from the surface of the concrete. In general, wet curing of concrete is performed so that a hydration reaction proceeds by applying a curing sheet for a predetermined period.

  As a specific method for the above-mentioned wet curing, there is a method of performing curing in a state where the concrete surface is covered with a curing sheet such as a nonwoven fabric while additionally supplying curing water to the surface of the concrete after demolding. Widely practiced (see, for example, Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 07-102763 JP 2010-24785 A

  By the way, the water required for the cement hydration reaction is about 40% of the cement weight, about 25% is chemically bonded to the cement, and 15% is adsorbed on the cement or the like as gel water. Has been. On the other hand, the water-cement ratio of general concrete is about 40 to 55%. In other words, it can be said that the concrete itself has the minimum amount of water necessary for cement hydration.

  Therefore, if the amount of water required for the hydration reaction can remain in the concrete before and after demolding, and the water can be used as moisture for curing, the watering process can be omitted in concrete production. Productivity can be increased (see FIG. 1).

  Here, the amount of water necessary for the hydration reaction in the concrete before and after the mold is removed is, for example, placing the concrete in a state in which a curing sheet is previously attached to the inner surface of the mold. This can be realized by performing

  Here, in a conventionally known process, when the procedure of simply pasting the curing sheet to the inner surface of the mold is adopted, wrinkles are generated on the surface of the curing sheet before demolding, or a part of the sheet In order to prevent the film from being peeled off from the mold, adhesion between the curing sheet and the mold is required. On the other hand, when the mold is removed, in order to leave the curing sheet on the concrete structure side, peelability between the curing sheet and the mold is required. It is extremely difficult to optimize both the adhesiveness to the formwork of the curing sheet and the peelability, which are conflicting requirements, and this is an obstacle to adopting the above highly productive process. It was. In the concrete construction manufacturing site, there has been a demand for a concrete manufacturing method capable of improving the productivity.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a concrete manufacturing method that can easily realize improvement in productivity by effectively utilizing moisture in the concrete.

  In the method for producing concrete, the present inventors use an adhesive composition containing water and a water-soluble adhesive as an adhesive used for pasting a curing sheet to be pasted on the inner surface of a mold in advance, The inventors have found that the above problems can be solved by limiting the concentration of the water-soluble adhesive in the adhesive composition to a concentration range determined through a plurality of steps unique to the present invention, thereby completing the present invention. It was. Specifically, the present invention provides the following.

  (1) Forming step, a curing sheet sticking step of sticking a curing sheet to a formwork for placing concrete using an adhesive composition containing water and a water-soluble adhesive, and the above-mentioned formwork A placing step of placing concrete with a curing sheet attached thereto; and, after placing the concrete, removing the mold while leaving the curing sheet on the surface of the concrete structure. A concrete structure comprising: a mold process; and a curing process for curing the concrete structure for a predetermined period in a state where the curing sheet is left on the surface of the concrete structure after the demolding process. The method comprises an adhesive selection step for predetermining an optimal concentration range of the water-soluble adhesive in the adhesive composition before the curing sheet sticking step, and the adhesive selection step comprises the steps of: By obtaining in advance a relationship between the concentration of the water-soluble adhesive in the adhesive composition and the contact area ratio of the curing sheet to the mold, an effective bonding state between the mold and the curing sheet is obtained. A first treatment for determining a first concentration range necessary for maintaining the indicated minimum contact area ratio, the concentration of the water-soluble adhesive in the adhesive composition, and the concrete structure of the curing sheet Determining the second concentration range necessary for maintaining the minimum remaining area ratio indicating an effective adhesion state between the curing sheet and the concrete structure by obtaining a relationship with the remaining area ratio in advance. The concentration of the region in which the contact area ratio is equal to or higher than the minimum contact area ratio and the remaining area ratio is equal to or higher than the minimum remaining area ratio from the processing 2 and the first concentration range and the second concentration range Range, And a third process for determining the optimum concentration range of the water-soluble adhesive.

  According to the invention of (1), the amount of water required for the hydration reaction is put into the concrete before and after demolding by pasting the curing sheet on the inner surface of the mold in advance prior to the placing step. The water can be utilized as moisture for curing.

  On the other hand, in the invention of (1), the adhesive used for sticking the curing sheet to the mold is an adhesive composition containing water and a water-soluble adhesive, and the concentration range is subjected to the above-described unique treatment. By limiting the concentration range to be determined, in the above process, the problem relating to the balance between adhesion and peelability between the curing sheet and the formwork, which is usually a problem, can be solved very easily and reliably. it can. That is, the conflicting demands of adhesiveness at the time of sticking to the mold and peelability from the mold at the time of demolding can be optimized easily and with high certainty in a series of processes.

  Therefore, according to the invention of (1), concrete having sufficiently high quality can be manufactured under high productivity.

  (2) The method for producing a concrete structure according to (1), wherein the water-soluble adhesive is polyvinyl alcohol, and the concentration of the polyvinyl alcohol in the adhesive composition is 1% or more and 5% or less.

  According to the invention of (2), the excellent quality improvement effect relating to the concrete produced by the method for producing a concrete structure as described in (1) is stabilized using a general-purpose water-soluble adhesive that is generally easily available. Can enjoy it.

  (3) The manufacturing method of the concrete structure as described in (1) or (2) which performs the said curing sheet sticking process before the said formwork installation process.

  According to the invention of (3), the curing sheet can be attached more accurately and more easily. Even if there is a reinforcing bar that forms part of the structure, a separator that is a holding material for the formwork, and the stenosis in the formwork, it should be constructed accurately and easily as described above. Can do.

  (4) The method for producing a concrete structure according to any one of (1) to (3), wherein the predetermined period in the curing step is 30 days or more after demolding of the formwork.

  According to invention of (4), the quality improvement effect of the concrete manufactured by the concrete manufacturing method by implementation of the manufacturing method of the concrete structure of (1) to (3) can be made higher.

  (5) The method for producing a concrete structure according to any one of (1) to (3), wherein the predetermined period in the curing step is 90 days or more after demolding of the formwork.

  According to invention of (5), the quality improvement effect of the concrete manufactured by the concrete manufacturing method by implementation of the manufacturing method of the concrete structure of (1) to (3) can be made still higher. In addition, according to invention of (5), it is also possible to perform a long-term curing, leaving a curing sheet as it is for about one year after demolding of a formwork.

  (6) The curing sheet used in the placing step is a sheet composed of polypropylene, polyethylene terephthalate, polyvinylidene chloride, or polyvinyl chloride, according to any one of (1) to (5). A method for manufacturing a concrete structure.

  According to the invention of (6), a cheaper curing sheet can be provided, and the curing period of concrete can be easily lengthened by leaving it on the concrete surface even after demolding.

  (7) The method for producing a concrete structure according to any one of (1) to (6), wherein a thickness of the curing sheet used in the placing step is 0.1 mm or more.

  According to the invention of (7), wrinkles are unlikely to occur in the curing sheet, and the appearance of the manufactured concrete structure can be further improved and the design can be improved.

  (8) The method for producing a concrete structure according to any one of (1) to (7), wherein the concrete is blast furnace cement concrete.

  According to the invention of (8), it is a case where blast furnace cement concrete, which requires a lot of moisture due to the progress of the hydration reaction, is used as a material compared to the concrete using ordinary Portland cement which is generally widely used. Moreover, the manufacturing method of the concrete structure of (1) to (7) can be implemented. This can greatly contribute to reducing the environmental load.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the concrete which can implement | achieve the improvement of productivity by effective utilization of the moisture in concrete can be provided easily.

It is a comparison object figure of the process of the manufacturing method of the concrete structure of this invention, and the conventional method. In the manufacturing method of the concrete structure of this invention, a curing sheet is stuck on a formwork, and it is a perspective view which shows the state which started placing. It is a comparison object figure with the conventional method about the aspect of sticking of the curing sheet in the manufacturing method of the concrete structure of this invention. It is a perspective view which shows the demolding process in the manufacturing method of the concrete structure of this invention. It is a top view which shows the state after demolding in the manufacturing method of the concrete structure of this invention. It is a top view which shows the curing process in the manufacturing method of the concrete structure of this invention. It is a perspective view which shows the curing sheet used for the manufacturing method of the concrete structure of this invention. It is a graph with which it uses for description of the optimal concentration range of the water-soluble adhesive used for the manufacturing method of the concrete structure of this invention.

  Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiment.

<Manufacturing method of concrete structure>
First, a method for producing a concrete structure using the resin curing sheet 10 shown in FIG. In the following description, an example using the curing sheet 10 in the form shown in FIG. 7A will be described, but the same applies to the case where the curing sheet 20 in the form shown in FIG. 7B is used. In addition, a conventionally well-known curing sheet can be used suitably for a curing sheet. Details of the curing sheet will be described later.

[Overview of overall process]
As shown in FIG. 1, the concrete structure manufacturing method P of the present invention includes an adhesive selection step ST10, a curing sheet sticking step ST20, a mold installation step ST30, a placing step ST40, a demolding step ST50, and a curing step ST60. This is an essential process. In addition, the curing sheet 10 is pasted in the mold 30 in advance by the curing sheet pasting step ST20 using the adhesive composition selected in the adhesive selecting step ST10, prior to the placing step ST40 (FIG. 2), in the demolding step ST50, only the mold 30 is demolded from the concrete structure with the curing sheet 10 left on the concrete surface (see FIG. 4). And curing process ST60 is performed, maintaining the aspect which the curing sheet 10 closely_contact | adhered to the concrete structure surface. As the moisture necessary for curing, the moisture in the concrete held by the curing sheet 10 previously attached in the mold 30 prior to the placing step ST40 is utilized as it is. Therefore, curing step ST60 before watering step ST70 that has been indispensable in the conventional process P _0, in the manufacturing method P of the invention is basically not required. For example, even when performing watering for fine adjustment of the amount of water, it is sufficient to supply much less curing water as compared with the conventional method.

[Adhesive selection process]
The production method P of the present invention is characterized in that the adhesive selection step ST10 is performed prior to other steps. Hereinafter, the adhesive selection method in the adhesive selection step ST10 will be described in detail.

  In adhesive selection process ST10, the adhesive composition containing water and a water-soluble adhesive which is the adhesive used in curing sheet sticking process ST20 is selected. In addition, since the adhesive composition selected by this adhesive selection process ST10 can apply the said selection result also to each process performed after that on the same conditions, in that case, said each individual In this process, the implementation of this process can be omitted. However, even when a specific adhesive selection process is omitted for such a reason, as long as the selection of the adhesive is substantially performed by the method of the present invention, Implementation of such a manufacturing process is naturally within the scope of the present invention as long as the results of the selection of the adhesive by the method are incorporated.

  In the production method of the present invention, an adhesive composition containing water and a water-soluble adhesive is used as the adhesive. And the density | concentration of the water-soluble adhesive in this adhesive composition is determined by adhesive selection process ST10. The concentration of the water-soluble adhesive is determined through a first to third three-stage process which will be described in detail below.

  And in the manufacturing method P of this invention, in the curing sheet sticking process ST20 which is the next process of adhesive selection process ST10, on the inner surface of the mold 30 for placing concrete, that is, on the concrete side surface to be placed, The curing sheet 10 is pasted with an adhesive composition whose concentration has been adjusted in advance within the predetermined concentration range determined in the adhesive selection step ST10 (see FIG. 3).

  Here, the conventionally well-known general sticking method which sticks the curing sheet 10 to the formwork 30 is demonstrated first. Conventionally, two methods shown in FIGS. 3B and 3C have been appropriately selected as the attaching method. One method is a method (FIG. 3B) in which an adhesive Ad such as a double-sided tape or glue is physically applied and held by the adhesive force of the substance. The other method is a method of sticking and holding the sheet by the surface tension using a liquid such as water W (FIG. 3C).

  Here, the requirements which are important in attaching the curing sheet 10 to the mold 30 and maintaining the adhesion are mainly the following requirements (i) to (iii). That is, (i) adhesion retention to the mold, (ii) releasability from the mold at the time of demolding (for the purpose of leaving the curing sheet on the concrete structure side), and (iii) sticking It is three points of work ease of work. In particular, adhesiveness retention to the formwork and peelability from the formwork at the time of demolding are basically contradictory physical property requirements, both of which can be stably expressed in a balanced manner. It was extremely difficult.

  The method of sticking and holding using the adhesive Ad shown in FIG. 3 (b) is excellent in the close contact holding property (i) to the mold. However, the releasability (ii) from the mold at the time of demolding is not suitable, and it is easy to apply the curing sheet to the mold without leaving any wrinkles for the workability (iii) of the affixing work. is not.

  On the other hand, the method using the surface tension of water W or the like shown in FIG. 3B is relatively easy to apply, and is excellent in workability (iii) of the application. Further, peeling from the mold at the time of demolding is very easy, and there is no problem with the peelability (ii) from the mold at the time of demolding. Further, unlike organic solvents, there is also a merit that the adverse effect on the concrete due to the remaining components after demolding is extremely small. However, the close contact retention property (i) to the formwork is not always sufficient and cannot satisfy the required level.

  As described above, attachment by the conventional method has both advantages and disadvantages and cannot satisfy the above three main requirements. On the other hand, according to the production method of the present invention, as shown in FIG. 3A, an adhesive composition Adw / W comprising water W and a predetermined concentration of water-soluble adhesive Adw is used. Thus, all the above three main requirements can be met in a balanced manner. That is, in the production method of the present invention, the concentration of the water-soluble adhesive Adw in the water-soluble adhesive Adw / W is specifically determined based on a criterion based on original knowledge. And adhesive composition Adw / W adjusted to the predetermined density | concentration determined in that way is selected as an adhesive agent for affixing a curing sheet on a formwork. According to the manufacturing method of the present invention in which such a process is an indispensable constituent requirement, a preferable adhesion retention property and a preferable peeling property are balanced between the curing sheet 10 and the mold 30 in the manufacturing process of the concrete structure. It can be expressed well.

  According to the adhesive composition Adw / W according to the production method of the present invention, when the curing sheet 10 is affixed to the formwork 30, the surface tension of the water W superior in workability and workability is utilized. Regarding the adhesion and retention of the curing sheet 10 to the mold 30 that is required after the pasting until the demolding, the physical adhesion effect of the water-soluble adhesive Adw can be used. Thereby, the curing sheet 10 can be attached to the mold 30 while satisfying the requirements (i) to (iii).

  As described above, the adhesive composition Adw / W used in the method for producing a concrete structure of the present invention is characterized in that its concentration is limited to a specific range based on selection criteria based on unique knowledge. The basic concept and specific processing procedure for determining the optimum density range will be described below.

(First process)
In the first treatment in the adhesive selection step ST10, a relationship between the concentration of the water-soluble adhesive Adw in the adhesive composition Adw / W and the contact area ratio of the curing sheet 10 to the mold 30 is obtained in advance. After clarifying the correlation between the concentration and the contact area ratio, it is necessary to determine at least the concentration necessary for maintaining the minimum contact area ratio indicating an effective adhesion state between the mold 30 and the curing sheet 10 based on the correlation. The range is determined as the “first concentration range”.

  In the present specification, the contact area ratio of the curing sheet to the mold (hereinafter, also simply referred to as “contact area ratio”) refers to the application surface of the curing sheet 10 applied to the mold 30 in the curing sheet application process ST20. Among these, it refers to the area ratio of the portion (the portion that is not peeled off) that is in close contact with the application surface of the mold 30 immediately before the placing step ST40. This contact area ratio does not hold the surface of the curing sheet 10 affixed to the mold 30 with, for example, a portion that is photographed with a digital camera and that is kept in close contact with image analysis software (a portion that is not peeled). Pixel (pixel) data can be binarized in brightness (black and white) in a portion, and the ratio of the number of pixels can be measured and calculated as an area ratio. At this time, it is a condition that shooting is performed with the number of pixels that does not cause a difference in the result depending on the number of set pixels at the time of shooting.

  Further, the minimum contact area ratio, which is a necessary minimum value of the contact area ratio of the curing sheet 10 to the mold 30, should be determined individually according to the operation conditions and the members to be used at each operation site, Although it is not a numerical value that should be uniquely fixed, it is generally a general guide that it is about 50% or more.

  In addition, the general standard of the contact area ratio of 50% or more is necessary to prevent the curing sheet from being peeled off during the period from the time when the curing sheet is pasted to the time when the formwork is installed and further when the molding is placed. This is an example of a general guideline from the viewpoint of securing a minimum area ratio. For example, when the surface quality of special concrete is required, specific numerical values of the minimum contact area ratio are set for each operation site, such as setting a higher contact area ratio as the minimum contact area ratio in advance. What is necessary is just to determine suitably according to conditions.

(Second process)
In the second treatment in the adhesive selection step ST10, the relationship between the concentration of the water-soluble adhesive Adw in the adhesive composition Adw / W and the remaining area ratio of the curing sheet 10 on the concrete structure is obtained in advance. After clarifying the correlation between the concentration and the remaining area ratio, the concentration range necessary for maintaining the remaining area ratio indicating the effective adhesion state between the mold 30 and the concrete structure is determined from the correlation. , “Second concentration range”.

  In this specification, the remaining area ratio of the curing sheet to the concrete structure (hereinafter, also simply referred to as “remaining area ratio”) refers to the application of the curing sheet 10 applied to the mold 30 in the curing sheet application process ST20. Of the surfaces of the curing sheet 10 affixed to the mold 30, the portion left on the affixing surface of the concrete structure when the mold 30 is demolded in the demolding step ST <b> 50 (peeling from the mold 30 Area ratio). This remaining area ratio can also be measured and calculated by the same method as the measurement and calculation method of the contact area ratio described above.

  Moreover, the minimum remaining area ratio, which is a necessary minimum value of the remaining area ratio of the curing sheet 10 to the concrete structure, should be determined individually according to the operating conditions and the members to be used at each operation site, Although it is not a numerical value that should be uniquely fixed, it is generally a general guide that it is about 70% or more.

  In addition, the general standard that the remaining area ratio is about 70% or more is a standard that incorporates the risk that the peeling further proceeds partially due to external factors such as wind and rain after demolding. Even if there is a partial progress of peeling, it is a standard that is assumed to be a preferable index for maintaining the contact area ratio at 50% or more over a necessary period. The remaining area ratio may also be appropriately determined according to various conditions for each operation site.

(Third process)
In the second process in the adhesive selection step ST10, from the “first density range” obtained by the first process and the “second density range” obtained by the second process to the form of the curing sheet. The concentration range of the region where the contact area ratio of the sheet is equal to or higher than the minimum contact area ratio and the remaining area ratio of the curing sheet on the concrete structure is equal to or higher than the minimum remaining area ratio is determined as the optimum concentration range of the water-soluble adhesive. .

  More specifically, the third process can be performed by a method using a graph as shown in FIG. 8, for example. FIG. 8 shows the relationship between the concentration of the water-soluble adhesive Adw in the adhesive composition Adw / W determined by the first treatment and the contact area ratio of the curing sheet 10 to the mold 30 and the second treatment. It is an example of the graph which described the relationship between the density | concentration of the water-soluble adhesive Adw in adhesive composition Adw / W, and the remaining area ratio to the concrete structure of the curing sheet 10 on the same plane coordinate, respectively.

  For example, in the graph of FIG. 8, when the concentration is less than α1, the remaining area ratio is sufficient, but the contact area ratio is lower than the minimum contact area ratio. On the other hand, when the concentration exceeds α2, the contact area ratio is sufficient, but the remaining area ratio is lower than the minimum remaining area ratio. When the concentration is greater than or equal to α1 (first concentration range) and less than or equal to α2 (second concentration range), the contact area ratio is equal to or greater than the minimum contact area ratio, and the remaining area ratio is equal to or greater than the minimum remaining area ratio. A method for determining this concentration range as the optimum concentration range (α1 to α2) can be exemplified as a suitable specific method for carrying out the present invention.

  As the water-soluble adhesive Adw to be contained in the adhesive composition Adw / W, water-soluble adhesives such as polyvinyl alcohol (PVA) or various acrylic adhesives can be appropriately used. Among them, PVA can be particularly preferably used as the water-soluble adhesive Adw from the viewpoint that the shrinkage after drying of the solvent is small, that is, the water absorption expansion is preferable.

  In the method for producing a concrete structure of the present invention, as described above, the adhesive used for sticking the curing sheet is first limited to an adhesive composition Adw / W containing water and a water-soluble adhesive Adw, and By optimizing the concentration of the water-soluble adhesive Adw in the adhesive composition Adw / W to a unique range according to the original criteria of the present application, it has been conventionally considered difficult between the curing sheet and the formwork. It is characterized in that it is possible to stably and easily express a good balance between adhesion retention and peelability.

[Curing sheet pasting process]
In the curing sheet sticking step ST20, as shown in FIG. 3, the curing sheet 10 is selected in the adhesive selecting step ST10 on the inner surface of the concrete casting form 30, that is, the concrete-side surface to be placed. It sticks by the adhesive composition Adw / W made.

  In the curing sheet sticking step ST20, it is preferable to stick the curing sheet 10 in advance in the mold 30 before the mold setting step ST30. However, after the setting of the mold 30 in the mold setting step ST30 described below, The curing sheet 10 may be affixed to the installed formwork 30. In any case, the curing sheet 10 can be attached by laying the curing sheet 10 after applying the adhesive composition Adw / W to the mold 30. The method of applying the adhesive composition Adw / W to the mold 30 is not particularly limited, but it is currently generally used for coating an interior cloth or paint from the viewpoint of making the coating amount uniform. An example of a preferable method is a method using a roller handle. Further, the application amount may be an amount within a range in which no dripping or the like occurs after application, and no uncoated residue occurs.

  Further, when the mold 30 is installed, the protrusions 16 of the curing sheet 10 affixed to the inner surface of the mold 30 at the boundary between adjacent molds 30 are substantially perpendicular to the concrete placement side from the mold 30. It is preferable to hold in a folded state so as to be.

[Formwork installation process]
In the mold installation step ST30, the mold 30 is installed at a predetermined position. The molds 30 are installed without gaps, but an interval of about 30 to 40 mm, for example, is left between the curing sheets 10. This is because it is difficult to construct the end portion 14 of the curing sheet 10 in a straight line and to completely match the end portion of the mold 30 in consideration of the construction accuracy of the curing sheet 10. As described above, the curing sheet 10 may be affixed to the installed mold 30 after the mold 30 is installed.

  In the mold installation step ST30, when the mold 30 is installed, as shown in FIG. 2, the end of the curing sheet 10 attached to the inner surface of the mold 30 at the boundary of the mold 30 is the mold 30. It is made to fold so that it may become a substantially right angle from, and it should be made to embed in the concrete at the time of concrete placement at the time of concrete placement in this placement sheet ST40 in the following placing process ST40. Is preferred. Thereby, since the edge part of a curing sheet can be easily fixed in the boundary vicinity of a formwork, construction of a curing sheet and a formwork can be implemented more easily. At this time, the curing sheets 10 are arranged with a predetermined interval between the curing sheets 10, and the space portion between the curing sheets 10 is exposed between the curing sheets as shown in FIG. 4. It is preferable to cover the concrete surface with a tape member after the mold is removed.

[Placement process]
Subsequently, in the placing step ST40, when the mold 30 with the curing sheet 10 attached thereto is installed at a predetermined position, the concrete C is poured into the mold 30 as shown by the arrows in FIG. Make a placement. When the placement is performed, the folded back protrusion 16 of the curing sheet 10 is embedded in the concrete C. The protrusion 16 has a rigidity capable of maintaining its shape even when embedded in the concrete C, and has a property of adhering to the concrete C. The curing sheet is more stably fixed to the concrete C by embedding the protrusions 16. The folded curing sheets 10 are spaced apart from each other as described above. After placing concrete, compact using a vibrator or the like. As a result, the concrete C can sufficiently flow into every corner of the mold 30.

[Demolding process]
When the setting of the concrete C has progressed to some extent and hardened, a demolding step ST50 for demolding the mold 30 is performed as shown in FIG. At the time of demolding, the curing sheet 10 stuck in the mold 30 is left on the concrete C as it is. By leaving the curing sheet 10, the wet curing of the concrete can be continued as it is after the mold 30 is removed.

  As described above, since there is a gap between the curing sheets 10 (at the boundary of the formwork) and the surface of the concrete C is exposed, as shown in FIG. A tape member) is applied to prevent moisture from escaping from the concrete C. FIG. 5 shows a state in which the gum tape 40 is applied to prevent moisture from escaping.

[Curing process]
After removing the mold 30, the curing step ST <b> 60 for curing the concrete structure C for a predetermined period is performed using the curing sheet 10 left on the sticking surface of the concrete structure C. In the curing step ST60, the mold 30 has already been removed, and the curing can be continued for a long time without using any special equipment by simply leaving the sheet-shaped curing sheet 10 on the concrete surface. For example, curing may be continued for 30 days or more after the mold 30 is removed, or curing may be continued for 90 days or more after the mold is removed. Furthermore, 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 of the concrete structure can be dramatically increased.

  After finishing the curing process ST60 after a predetermined curing period, the curing sheet 10 is removed from the concrete surface. At this time, if the gummed tape 40 is peeled off, the curing sheet is pulled by this, the protrusion 16 of the curing sheet 10 is cut at the dotted line portion (see FIG. 6), and the curing sheet 10 can be removed from the concrete structure. . Thereby, a concrete structure is completed.

  According to the manufacturing method P including the above steps, the curing sheet 10 is attached to the mold 30 using the adhesive composition Adw / W selected by the adhesive selection step ST10 unique to the present invention. Thus, as will be shown later in the examples, the adhesion retention property when the curing sheet 10 affixed to the mold 30 is adhered and the releasability at the time of demolding are each expressed in a preferable manner in each process step. The concrete structure can be produced in a preferred mode. As a result, it is possible to prevent a deterioration in the quality of the surface of the concrete structure due to the occurrence of the above-described wrinkles, and to manufacture a concrete structure having a good appearance and excellent design.

In the above method for producing a concrete structure, there is no restriction on the design standard strength of the concrete used in the placing process, and the above effects are exhibited in concrete in all strength ranges. For example, the concrete design standard strength is 18 N / It may be mm ² or more and 33 N / mm ² or less. According to the present invention, it is easy to take a long curing period, so a so-called high-strength concrete is not used, and a general concrete with reduced cost is used, and a concrete structure having compressive strength and durability higher than conventional ones. Can be manufactured.

  In addition, while using the blast furnace cement concrete, which can greatly contribute to the reduction of environmental load and requires a lot of moisture due to the progress of the hydration reaction, the high quality as described above using the production method of the present invention. The concrete structure can be manufactured. Thereby, it can also contribute greatly to environmental load reduction.

<Concrete curing sheet>
A concrete curing sheet that can be preferably used in the method for producing a concrete structure of the present invention will be described with reference to FIG. FIG. 7 shows a curing sheet that can be used in the method for producing a concrete structure of the present invention. As shown in FIG. 7A, the curing sheet 10 is a concrete curing sheet having a predetermined thickness, and has, for example, a substantially rectangular shape. The curing sheet 10 includes a rectangular sheet main body 12, end portions 14 positioned at both ends in the width direction of the sheet main body 12, and a plurality of protrusions 16 extending from the end portions 14 to the side where the concrete is placed. It is preferable that it is provided. In the present embodiment, the sheet main body 12, the end portion 14, and the protruding portion 16 are made of, for example, the same material and are integrally formed. However, the protruding portion 16 is provided as a separate body so as to be connected to the end portion 14. It may be. In addition, it is preferable that the thickness of the curing sheet 10 is about 0.1 mm or more and 2 mm or less. By setting the thickness of the curing sheet 10 to 0.1 mm or more, wrinkles are less likely to occur at the time of sticking, and the appearance of the manufactured concrete structure can be further improved and the design can be improved.

  Each protrusion 16 has a rectangular shape (sheet shape) having a vertical length of, for example, 5 to 50 mm (preferably 20 to 30 mm) and a depth of, for example, 1 to 20 mm (preferably 5 to 10 mm). Presents. The thickness of each protrusion 16 is, for example, 0.1 to 2 mm. Such protrusions 16 are arranged in a vertical direction at a predetermined interval, for example, 5 to 50 mm (preferably 10 to 30 mm), and the concrete is placed so as to be substantially orthogonal to the surface of the sheet main body 12. It is bent toward the side to be done. Most of the protrusions 16 are embedded in the concrete when the concrete is placed, and the curing sheet 10 is securely attached to the concrete.

  Moreover, you may use the sheet | seat of the structure shown by (b) of FIG. 7 as a curing sheet used by this embodiment. In the curing sheet 20 shown in FIG. 7B, similarly, a rectangular sheet body 22, end portions 24 positioned at both ends in the width direction of the sheet body 22, and concrete are cast from the end portions 24. And a plurality of protrusions 26 extending to the side. However, in the curing sheet 20, the protruding portion 26 has a different shape from the protruding portion 16 and has a needle shape. These projections 26 have a depth (needle length) of, for example, 1 to 20 mm (preferably 5 to 10 mm) and a thickness of, for example, 0.1 to 2 mm. Such protrusions 26 are arranged in a vertical direction at a predetermined interval, for example, 5 to 50 mm (preferably 10 to 30 mm), and concrete is placed so as to be substantially orthogonal to the surface of the sheet main body 22. It is bent toward the side to be done.

  It should be noted that a continuous body such as a kite string may be pasted so as to be sandwiched between the sheet and the concrete in the vicinity of the corners on the bent side of the projections 16 and 26 in the curing sheets 10 and 20 described above. Good. In this case, the removal operation at the time of sheet removal described later can be facilitated. Further, each curing sheet 10, 20 may be a rectangular sheet excluding the protrusions 16, 26. In this case, curing can be performed using an adhesive or other hook members as appropriate so that the curing sheets 10 and 20 are not peeled off from the concrete.

  Examples of the materials for the curing sheets 10 and 20 include polypropylene, polyamide or polyamide-based resin, perfluoroalkoxy fluororesin, tetrafluoroethylene / hexafluoropropylene copolymer, ethylene / tetrafluoroethylene copolymer, and polyethylene terephthalate. High molecular compounds such as (PET), polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, and polyolefin can be used. Considering the fact that it is affixed to the concrete surface as it is for a long curing period, curing is made of resins such as polypropylene, polyethylene terephthalate, polyvinylidene chloride, polyvinyl chloride, etc. Sheets are preferred. Among the above resins, polypropylene having excellent workability can be preferably used because of its extremely small specific gravity and high strength.

  In addition, it is preferable that the curing sheets 10 and 20 have a predetermined transparency so that the state of the concrete surface can be visually confirmed at any time during the curing period. Although the above-mentioned polypropylene can improve transparency by addition of a transparent nucleating agent or biaxial stretching, a highly transparent polypropylene subjected to such processing can be particularly preferably used.

The curing sheets 10 and 20 are preferably those having a low water vapor permeability of the sheet, the water vapor permeability of the sheet is preferably 10 g / m ² · 24 h or less, and the water vapor permeability of the sheet is 5 g / m ^2. and still more preferably m is ² · 24h or less. In this case, it is possible to further suppress permeation of water necessary for the hydration reaction.

The curing sheets 10 and 20 are preferably those having a low carbon dioxide permeability of the sheet, and the carbon dioxide permeability of the sheet is preferably 100,000 cc / m ² · 24 h · atm or less. The carbon dioxide permeability is more preferably 50,000 cc / m ² · 24 h · atm or less. In this case, carbon dioxide can be prevented from entering the surface of the concrete being cured, and neutralization of the surface of the concrete C can be suppressed. For example, it is preferable to use polypropylene that hardly absorbs water, and furthermore, by processing the surface of those materials by various surface processing techniques, a sheet with further reduced water vapor permeability or carbon dioxide permeability can be obtained. It can be preferably used.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

<Test Example 1> Using the following curing sheet and the following weir plate constituting the formwork, the difference in the attaching method is important for sticking the curing sheet 10 to the formwork 30 and further maintaining adhesion. A test for verifying the influence on the above requirements (i) to (iii) is conducted. In this test, using the curing sheet shown below and two types of molds, each curing sheet was affixed to the weir plate by a method different from each of the examples and comparative examples, and left outdoors for 5 days, and then demolded. Among the above three requirements, (i) to (iii) were observed. The adhesion retention to the mold of (i) was observed 7 days after the pasting, and the peelability from the mold during the removal of (ii) was observed immediately after the demolding. Regarding the ease of work in (iii), the ease of work was confirmed based on the feeling of the same general worker.

As the curing sheet, a curing sheet made of polypropylene having a size of 90 cm × 180 cm and a thickness of 200 μm (manufactured by Sekisui Molding Co., Ltd .: trade name “Polysem”) was used. As the weir plate, the following two kinds of weir plates were used. Dam plate 1: A mold made of wooden plywood was used. Weir plate 2: An NF board made of recycled resin was used as an inappropriate water weir plate.

(Examples 1-2) In Example 1, the said curing sheet was affixed on the dam plate 1 by the method similar to the method shown to Fig.3 (a). As the water-soluble adhesive Adw, an adhesive composition Adw / W containing PVA was used. The PVA concentration of the adhesive composition Adw / W was 3.0%. In Example 2, the curing sheet was affixed to the dam plate 2 under the same conditions as above except that the dam plate 2 was used instead of the dam plate 1.

(Comparative example 1) In the comparative example 1, the said curing sheet was affixed on the weir board 1 by the method similar to the method shown in FIG.3 (b). As the adhesive Ad, an adhesive mainly composed of styrene butadiene rubber (manufactured by Sumitomo 3M Limited: trade name “3M spray glue 77”) was used.

(Comparative Examples 2-3)
In Comparative Example 2, a method similar to the method shown in FIG. 3C, that is, a method of sticking the curing sheet to the surface of the dam plate using water W and its surface tension was used. In Comparative Example 3, a curing sheet was attached to the dam plate 2 under the same conditions as above except that the dam plate 2 was used instead of the dam plate 1.

The verification results in each example and comparative example are shown in Table 1. However, (i) and (ii) were evaluated according to the following criteria.
(I) Adhesion retention to formwork: “O” when the area ratio of the peeled portion of the curing sheet from the dam plate is approximately 50% or less, and approximately 70% or more of the curing sheet is peeled off It was set as “x”. An intermediate aspect of the exception is “Δ”.
(Ii) Peelability from the mold during demolding: “○” when the curing sheet was peelable from the barrier plate, and the curing sheet was not peelable from the barrier plate (attached to the barrier plate side) ) Was defined as “×”.
(Iii) Ease of operation: “◯” indicates that the curing sheet can be applied to the barrier plate without wrinkles, and “x” indicates that it cannot be applied without wrinkles.

  From Table 1, it can be seen that by using the adhesive composition Adw / W including water W and a predetermined concentration of the water-soluble adhesive Adw, all of the above three main requirements can be well balanced. .

<Test Example 2>
For Example 1 in Test Example 1, further, the correlation between the PVA concentration of the adhesive composition Adw / W and (i) the adhesion and retention to the mold, and (ii) the mold at the time of demolding A test was conducted to verify the correlation with the peelability from the frame. In the test, the PVA concentration of the adhesive composition Adw / W of Example 1 described above was 1% to 10% for each example, and for each concentration shown in Table 2, (i) adhesion to the mold For the property, the contact area ratio was measured and used as an index. Moreover, (ii) About the peelability from the mold at the time of demolding, the remaining area ratio was measured and used as the index. The measurement was performed five times for each PVA concentration, and the average value was taken as the measurement result. The measurement results are shown in Table 2. In FIG. 8, the results of Table 2 are plotted on the same coordinates, and an approximate curve is drawn to form a graph.

  From Table 2 and FIG. 8, for example, in the case of Example 1, assuming that the minimum contact area ratio in Example 1 is 50% and the minimum remaining area ratio is 70%, the water solubility in the water-soluble adhesive Adw / W The adhesion between the curing sheet and the formwork in the concrete structure manufacturing process is achieved by carrying out the manufacturing method of the present invention with the concentration of the adhesive Adw set to a concentration between α1 and α2 in FIG. It can be seen that retention and preferable peelability can be expressed in a balanced manner.

Diffuser 10 and 20 curing the seat 14, 24 the ends 16 and 26 projections 30 Formwork 40 gummed ST10 adhesive selection step ST20 curing sheet sticking step ST30 Formwork installing step ST40 stroke setting step ST50 demolding step ST60 curing step ST70 A process

Claims (8)

Formwork installation process,
A curing sheet sticking step of sticking a curing sheet to a formwork for placing concrete using an adhesive composition containing water and a water-soluble adhesive;
A placing step of placing concrete in a state where the curing sheet is affixed to the mold; and
A demolding step of demolding the formwork while leaving the curing sheet on the surface of the concrete structure after placing the concrete;
A curing process for curing the concrete structure for a predetermined period in a state where the curing sheet is left on the surface of the concrete structure after the demolding process, ,
Before the curing sheet sticking step, comprising an adhesive selection step for predetermining the optimum concentration range of the water-soluble adhesive in the adhesive composition,
The adhesive selection step includes
By obtaining in advance the relationship between the concentration of the water-soluble adhesive in the adhesive composition and the contact area ratio of the curing sheet to the mold, an effective bonding state between the mold and the curing sheet A first process for determining a first concentration range necessary to maintain a minimum contact area ratio indicating
By determining in advance the relationship between the concentration of the water-soluble adhesive in the adhesive composition and the remaining area ratio of the curing sheet to the concrete structure, the curing sheet and the concrete structure can be effectively used. A second process for determining a second concentration range necessary for maintaining the minimum remaining area ratio indicating the adhesion state;
From the first concentration range and the second concentration range, a concentration range of a region where the contact area ratio is equal to or higher than the minimum contact area ratio and the remaining area ratio is equal to or higher than the minimum remaining area ratio is defined as the water-soluble concentration range. And a third treatment determined as the optimum concentration range of the adhesive. The water-soluble adhesive is polyvinyl alcohol,
The method for producing a concrete structure according to claim 1, wherein a concentration of the polyvinyl alcohol in the adhesive composition is 1% or more and 5% or less.   The manufacturing method of the concrete structure of Claim 1 or 2 which performs the said curing sheet sticking process before the said mold installation process.   The method for producing a concrete structure according to any one of claims 1 to 3, wherein the predetermined period in the curing step is 30 days or more after the mold is removed.   The method for producing a concrete structure according to any one of claims 1 to 3, wherein the predetermined period in the curing step is 90 days or more after the mold is removed.   6. The concrete structure according to claim 1, wherein the curing sheet used in the placing step is a sheet made of polypropylene, polyethylene terephthalate, polyvinylidene chloride, or polyvinyl chloride. Method.   The method for producing a concrete structure according to any one of claims 1 to 6, wherein a thickness of the curing sheet used in the placing step is 0.1 mm or more.   The method for producing a concrete structure according to any one of claims 1 to 7, wherein the concrete is blast furnace cement concrete.

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