JP5774153B1 - Method for manufacturing concrete structure and concrete curing sheet - Google Patents

Abstract

[PROBLEMS] To provide a method for producing concrete capable of achieving both improvement in productivity through effective utilization of moisture in the concrete and maintaining the quality of the concrete at a sufficiently high level. A formwork installation step ST10 for installing a formwork 30 for placing concrete, a placement process ST20 for placing concrete with a curing sheet 10 attached to the inner surface of the formwork 30, and a concrete A demolding step ST30 for demolding the mold 30 after the casting, and a curing step ST40 for curing the concrete structure by leaving the curing sheet 10 on the surface of the concrete structure after the demolding step ST30. A method for producing a concrete structure in which the coefficient of linear expansion of the curing sheet 10 used in the placing step ST20 is 100 μ / ° C. or less. [Selection] Figure 9

Description

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

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

  As a specific method of the above-mentioned wet curing, there is a wide range of methods of curing while additionally supplying curing water to the concrete surface after demolding and covering the concrete surface with a curing sheet such as a nonwoven fabric. (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 remains in the concrete before and after mold removal, 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. 3).

  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 However, in the conventionally known process, when the procedure of simply applying the curing sheet to the inner surface of the mold is adopted in advance, the curing sheet is removed during the curing period of the curing sheet from before the placement to the curing period. On the other hand, it has been found that wrinkles occur on the surface, resulting in a problem that the surface quality of the concrete deteriorates. However, the present condition is that the effective solution means with respect to generation | occurrence | production of said wrinkles which generate | occur | produce during the sticking period over a long term of a curing sheet has not yet been found.

  There is still no means that can achieve a high level of improvement in productivity through effective utilization of moisture in the concrete and maintenance of the surface quality of the concrete. There has been a demand for a method for producing concrete that enables both quality and maintenance of quality.

The present invention has been made to solve the above-mentioned problems, and its purpose is to achieve both improvement in productivity through effective utilization of moisture in the concrete and maintaining the quality of the concrete at a sufficiently high level. An object of the present invention is to provide a method for manufacturing concrete.

  The present inventors sufficiently suppress the generation of wrinkles by limiting the curing sheet to be applied to the inner surface of the mold in advance prior to the placing process to a sheet having a linear expansion coefficient of 100 μ / ° C. or less. The present inventors have found that this can be done and have completed the present invention. Specifically, the present invention provides the following.

  (1) Forming process for installing a formwork for placing concrete, placing process for placing concrete with a curing sheet attached to the inner surface of the formwork, and after placing the concrete A demolding step of demolding the mold, and a curing step of leaving the curing sheet on the surface of the concrete structure after the demolding step, and curing the concrete structure for a predetermined period, The curing sheet is a method for producing a concrete structure having a linear expansion coefficient of 100 μ / ° C. or less.

  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 used as moisture for curing.

  On the other hand, in the invention of (1), by setting the linear expansion coefficient of the curing sheet to 100 μ / ° C. or less which is a specific range of the present application, in the above process, generation of wrinkles in the curing sheet that is usually a problem is sufficiently achieved. Can be suppressed.

  Therefore, according to the invention of (1), in the above-mentioned process in which the step of additionally supplying curing water is unnecessary and the productivity is increased, while preventing the deterioration of the concrete surface quality due to the occurrence of the above-mentioned wrinkles, The hydration reaction can sufficiently proceed. Thereby, according to invention of (1), concrete provided with sufficiently high quality can be manufactured under high productivity.

  (2) The method for producing a concrete structure according to (1), wherein the curing sheet has a linear expansion coefficient of 80 μ / ° C. or less.

  According to the invention of (2), generation | occurrence | production of the wrinkle of a curing sheet can be prevented further more reliably, and the quality improvement effect at the time of implementation of invention of (1) can be expressed more stably.

  (3) The method for producing a concrete structure according to (1) or (2), further including a curing sheet pasting step of pasting the curing sheet in advance in the mold before the mold setting step.

  According to the invention of (3), the curing sheet can be applied more accurately and more easily. In particular, even in the case where there is a reinforcing bar that is a part of the structure, a separator that is a holding material for the mold, and the like, in which the workable range becomes narrow, the mold is accurate, and Easy to install.

  (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 7 days or more after the mold is removed.

  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 28 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 higher.

  (6) The method for producing a concrete structure according to any one of (1) to (3), wherein the predetermined period in the curing step is 91 days or more after demolding of the formwork.

  According to the invention of (6), the quality improvement effect of the concrete produced by the concrete production method according to the implementation of the concrete structure production method of (1) to (3) can be made extremely high. it can. In addition, according to invention of (6), 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.

  (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 less likely to occur in the curing sheet, and the appearance of the manufactured concrete structure can be further improved.

  (8) When installing the formwork in the formwork installation step, the end of the curing sheet attached to the inner surface of the formwork at the boundary of the formwork is folded back so as to be substantially perpendicular to the formwork. In the placing step, the cured sheet is fixed by embedding the folded protrusions in the concrete when placing the concrete, and the folded cured sheets are spaced apart from each other by a predetermined distance. The method for producing a concrete structure according to any one of (1) to (7), wherein:

  According to invention of (8), 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 made easy.

  (9) In any one of (1) to (8), the concrete surface exposed between the curing sheets disposed at a predetermined interval is covered with a tape member after the mold is removed. The manufacturing method of the concrete structure of description.

  According to the invention of (9), when carrying out the method for producing a concrete structure of (1) to (8), it is possible to suppress moisture dissipation from the concrete and perform more reliable curing.

  (10) The method for producing a concrete structure according to any one of (1) to (9), wherein the concrete is blast furnace cement concrete.

  According to the invention of (10), in comparison with concrete using ordinary Portland cement, which is generally widely used, the material is blast furnace cement concrete that requires more moisture due to the progress of the hydration reaction. Moreover, the manufacturing method of the concrete structure of (1) to (9) can be implemented. This can greatly contribute to reducing the environmental load.

  (11) A curing sheet that is affixed to the inner surface of a formwork for concrete placement and used for curing the concrete, and that uses a thermoplastic resin as a base resin and has a linear expansion coefficient of 100 μ / ° C. or less.

  According to the invention of (11), in the concrete manufacturing process in which the step of additionally supplying curing water is not required and the productivity is increased, the deterioration of the concrete surface quality due to the occurrence of sheet flaws is sufficiently prevented. The hydration reaction can proceed. Thereby, according to invention of (11), concrete provided with sufficiently high quality can be manufactured under high productivity.

  (12) The concrete curing sheet according to (11), wherein the linear expansion coefficient is 80 μ / ° C. or less.

  According to the invention of (12), generation of wrinkles on the curing sheet can be further reliably prevented, and the quality improvement effect at the time of implementing the invention of (11) can be expressed more stably.

  (13) The concrete curing sheet according to (11) or (12), wherein the thermoplastic resin is an olefin resin.

  According to the invention of (13), in addition to the fact that the linear expansion coefficient is in the above range, the invention of (11) or (12) is more preferable by adopting an olefin resin that is also excellent in transparency and weather resistance. It can be implemented in an embodiment.

  (14) The concrete curing sheet according to (13), wherein the olefin resin is an olefin thermoplastic elastomer.

  According to the invention of (14), by making the curing sheet of (13) a more flexible curing sheet, the adhesion to concrete is enhanced, and the invention of (13) is carried out in a more preferred embodiment. Can do.

  (15) The concrete curing sheet according to any one of (11) to (14), comprising 100 parts by weight of a thermoplastic resin and 10 to 50 parts by weight of an inorganic filler.

  According to the invention of (15), even if the linear expansion coefficient of the base resin is high, the invention can be carried out in a sufficiently preferable mode by reducing this, and the inventions of (11) to (14). .

  (16) The concrete curing sheet according to (15), wherein the inorganic filler is a silicic acid-containing material.

  According to the invention of (16), the invention of (15) can be implemented in a more preferable aspect.

  (17) The concrete curing sheet according to any one of (11) to (16), wherein the thickness of the sheet is 0.1 mm or more.

  According to the invention of (17), wrinkles are less likely to occur in the curing sheet, and the appearance of the manufactured concrete structure can be further improved.

  (18) It further includes a plurality of needle-like or sheet-like projections arranged at the end of the sheet body, and the plurality of projections are arranged at predetermined intervals so as to be substantially orthogonal to the surface of the sheet body. The concrete curing sheet according to any one of (11) to (17).

  According to invention of (18), a curing sheet can be easily attached to concrete at the time of concrete placement by using this projection part.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of concrete which can be compatible with the improvement of productivity by effective utilization of the water | moisture content in concrete, and maintaining the quality of concrete to a sufficiently high level can be provided.

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 schematic diagram which shows the contact angle to the water of the surface of the curing sheet of this invention. 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 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 a part of curing process in the manufacturing method of the concrete structure of this invention. It is a perspective view which shows the outline | summary of the test body used for the Example. It is a graph which shows the measurement result of the peeling area rate in an Example. It is a graph which shows the measurement result of the neutralization depth in an Example. It is a graph which shows the measurement result of the surface water absorption rate in an Example. It is an enlarged photograph which shows the concrete surface (Example) in a comparative test. It is an enlarged photograph which shows the concrete surface (comparative example) in a comparative test.

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

<Concrete curing sheet>
First, a concrete curing sheet used in the method for producing a concrete structure of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a curing sheet used in the method for producing a concrete structure of the present invention. As shown in FIG. 1A, 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 located at both ends in the width direction of the sheet main body 12, and a plurality of protrusions 16 extending from both 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. It may be.

  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 concrete is placed so as to be substantially orthogonal to the surface of the sheet main body 12. It is bent toward the side. 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. 1 as a curing sheet used by this embodiment. Similarly, the curing sheet 20 shown in FIG. 1B is formed by placing concrete from a rectangular sheet main body 22, end portions 24 positioned at both ends of the sheet main body 22 in the width direction, and both 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.

  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.

  The curing sheet uses a thermoplastic resin as a base resin, and has a linear expansion coefficient of 100 μ / ° C. or less. Curing sheets are affixed to the inner surface of concrete casting molds and used for curing concrete. However, when manufacturing concrete structures, especially huge concrete structures such as bridges and dams, the curing sheet is concrete. Since it is affixed to the inner surface of the casting formwork and exposed to the outside air for a long period of several days to several tens of days, if the curing sheet has a high coefficient of linear expansion, the expansion and contraction are repeated and deformed during that time, When the concrete is placed after peeling from the formwork, the deformed shape is transferred to the surface of the concrete structure and the surface property of the concrete structure is deteriorated. The expansion coefficient is 100 μ / ° C. or less, preferably 80 μ / ° C. or less.

When the water vapor permeability of the curing sheet is increased, the breathing water generated when curing the concrete is permeated and dissipated, and the effect of contributing to the hardening of the concrete is reduced. The transmittance is preferably 10 g / m ² · 24 hr or less, and more preferably 5 g / m ² · 24 hr or less. In addition, the said water-vapor-permeation rate is the average value performed by test number 3 by 20 degreeC and 60% of humidity RH by the cup method based on JISZ0208 (1976).

Further, when the carbon dioxide permeability of the curing sheet is increased, carbon dioxide penetrates into the concrete surface when curing the concrete, the concrete is neutralized, and the reinforcing bars embedded in the concrete are easily corroded. The carbon permeability is preferably smaller, and the carbon dioxide permeability is preferably 100,000 ml / m ² · 24 hr · atm or less, more preferably 50,000 ml / m ² · 24 hr · atm or less. The carbon dioxide permeability is a value obtained in accordance with JIS K7126 (2006) by a differential pressure method at 20 ° C., humidity 0% RH, and number of tests 1.

In addition, the linear expansion coefficient in this specification is a value quantitatively evaluated by linear thermal expansion ΔL / L0. The linear thermal expansion is defined by a ratio of elongation ΔL = L (T) −L0 at the temperature T to the length L0 at the reference temperature. In this specification, all the reference temperatures were set to an absolute temperature of 293.15 K (20.0 ° C.). That is, L0 = L (293.15K). In the case of an isotropic substance, the product obtained by dividing the body thermal expansion ΔV / V by 3 corresponds to the linear thermal expansion, and all of the examples are isotropic. The temperature differential of this linear thermal expansion is an amount defined as the linear expansion coefficient. The unit of linear expansion coefficient is μ / ° C. (μ = 10 ⁻⁶ ).

  When the thickness of the curing sheet is reduced, there are drawbacks such as difficulty in handling during construction and easy opening of holes due to sparks when welding the core steel frame. In addition, breathing water is generated when curing concrete, but it is pushed back into the concrete to harden the concrete efficiently and prevent leaching of the breathing water to the interface between the formwork and concrete. The thickness of the curing sheet is preferably from 0.1 to 5.0 mm, more preferably from 0.12 to 2.0 mm, since it is preferable to have sufficient rigidity and self-supporting property.

  The curing sheet is a sheet having a thermoplastic resin as a base resin. Examples of the thermoplastic resin include olefin-based materials such as low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and olefin-based thermoplastic elastomer. Resins; Polyamide; Polyethylene terephthalate; Polycarbonate; Vinyl chloride resins such as polyvinyl chloride, chlorinated polyvinyl chloride, and polyvinylidene chloride; and olefins that have excellent physical properties, transparency, and weather resistance. System resins are preferred. Moreover, the extending | stretching sheet | seat of these thermoplastic resin sheets may be sufficient.

  In addition, the curing sheet needs to be adhered along the inner surface of the formwork and also needs to adhere to the concrete to be placed. Elastomers are more preferred. The olefin-based thermoplastic elastomer is an ethylene-propylene copolymer or a molten mixture or polymerization reaction product of polypropylene and ethylene-propylene rubber. For example, “Prime TPO” manufactured by Prime Polymer Co., Ltd. and “Newcon” manufactured by Nippon Polypro Co., Ltd. “Cataloy” manufactured by Sun Allomer, “Zeras” manufactured by Mitsubishi Chemical Corporation, and the like.

  Although the said curing sheet may be formed only from the said thermoplastic resin, when a linear expansion coefficient is high, an inorganic filler may be added in order to reduce a linear expansion coefficient. Examples of the inorganic filler include talc, mica, calcium silicate, magnesium silicate, calcium carbonate, calcium oxide, calcium hydroxide, magnesium hydroxide, barium hydroxide, titanium oxide, glass fiber, and carbon fiber. Inorganic fillers containing silicic acid such as mica, calcium silicate and magnesium silicate are preferable because the adhesion between the curing sheet and the concrete is improved and the curing effect is improved.

  Although the addition of the inorganic filler is effective in lowering the linear expansion coefficient, the physical properties such as water vapor permeability and carbon dioxide permeability are lowered. Therefore, it is necessary to balance these physical properties, and the thermoplastic resin 100 It is preferable to add in the range of 50 parts by weight or less with respect to parts by weight.

  In addition, it is preferable that the curing sheets 10 and 20 have a contact angle θ (wetting angle) of at least 50 degrees with water on the surface (contact surface) on the side in contact with the placed concrete. By processing the surface of the material by various surface processing techniques, the contact angle with water can be appropriately adjusted.

  In the method for producing a concrete structure according to the present invention, it is preferable to use a curing sheet having a contact angle with water of 50 degrees or more when placing. Thereby, when concrete hardens | cures after placement, generation | occurrence | production of the breathing water which generate | occur | produces normally can be suppressed more effectively. The generation of breathing water is suppressed in this way when the contact angle (also referred to as the wetting angle) of the sheet surface (contact surface) of the curing sheet covering the concrete surface is contained in the concrete. Water that is about to go out from the surface and the air that exists in the water is pushed back into the concrete at the sheet contact surface, and as a result, the water and the air inside it remain in the concrete and hardening progresses. it is conceivable that.

Here, the “contact angle θ” is an angle formed between the tangent of the droplet and the solid surface (sheet surface), as shown in FIG. It is.
γS: surface tension of solid γL: surface tension of liquid γSL: interfacial tension between solid and liquid

The “contact angle θ” can be measured by, for example, the θ / 2 method. Specifically, as shown in FIG. 2B, the radius r and height h of the droplet are obtained. And contact angle (theta) is calculated | required from the following Numerical formula (Equation 2) and (Equation 3).

<Manufacturing method of concrete structure>
Then, the method of manufacturing a concrete structure using the curing sheets 10 and 20 provided with the above structures is demonstrated. In the following description, an example using the curing sheet 10 will be described, but the same applies to the case where the curing sheet 20 is used.

[Overview of overall process]
As shown in FIG. 3, the method P for manufacturing a concrete structure of the present invention is a process in which a mold installation step ST10, a placement step ST20, a demolding step ST30, and a curing step ST40 are essential procedures. Incidentally, the curing sheet 10 is affixed in advance in the mold prior to the placing step ST20, and in the demolding step ST30, only the mold is left from the concrete structure with the curing sheet 10 left on the concrete surface. Demolded. Curing process ST40 is performed with the curing sheet 10 kept in close contact with the concrete structure. As the moisture necessary for curing, the moisture contained in the placed concrete held by the curing sheet 10 previously stuck in the mold prior to the placing step ST20 is utilized as it is. Therefore, the watering step ST50 that has been essential in the conventional process P ₀ is basically unnecessary in the manufacturing method P of the present invention. For example, even when watering is performed for fine adjustment of the amount of water, it is only necessary to supply much less curing water as compared with the conventional method.

[Formwork installation process]
First, as shown in FIG. 4, the curing sheet 10 of the present invention having a linear expansion coefficient within a predetermined range on the inner surface of the concrete casting mold 30 (that is, the concrete-side surface to be placed) as described above. Is attached in advance with an adhesive double-sided tape or the like (curing sheet attachment), and the mold 30 is placed 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. In addition, in order to affix the curing sheet 10 on the mold 30, the surface tension of water may be used instead of the double-sided tape, or grease or the like may be used. 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. Hold it in a folded state. The curing sheet 10 may be attached to the inner surface of the mold 30 after the mold 30 is installed.

[Placement process]
Subsequently, when the formwork 30 with the curing sheet 10 attached is installed at a predetermined position, the concrete C is poured into the formwork 30 as shown by arrows in FIG. 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 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, the mold 30 is removed as shown in FIG. At the time of demolding, the curing sheet 10 stuck in the mold 30 is stuck on the concrete C as it is. That is, the curing sheet 10 is left behind. By leaving the curing sheet 10, the wet curing of the concrete can be continued as it is, although the mold 30 is removed. As described above, since there is a gap between the curing sheets 10 (at the border 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. 6 shows a state in which the gum tape 40 is applied to prevent moisture from escaping.

[Curing process]
After removing the mold 30, the concrete structure is cured for a predetermined period using the curing sheet 10 left on the surface of the concrete structure. In the curing step ST40, 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, the curing may be continued for 7 days or more after the mold 30 is removed, or the curing may be continued for 28 days or more after the mold is removed, or 91 days or more. 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 a predetermined curing period and after finishing the curing process ST40, the curing sheet 10 is removed from the concrete surface. At this time, if the gum tape 40 is peeled off, the curing sheet is pulled by this, and the protrusion 16 of the curing sheet 10 is cut at the dotted line (see FIG. 7), and the curing sheet 10 can be removed from the concrete structure. . Thereby, a concrete structure is completed.

  As described above, according to the manufacturing method P according to the present embodiment, the curing sheet 10 of the present invention having a linear expansion coefficient in a predetermined range is used at the time of placement, and as will be shown later in the examples, the curing sheet affixed to the formwork. The occurrence of 10 wrinkles can be effectively suppressed. Therefore, it is possible to prevent a deterioration in the quality of the surface of the concrete structure due to the occurrence of the wrinkles and to produce a concrete structure with a good appearance.

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.

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

First, concrete materials and blends shown in Tables 1 and 2 below were prepared.

Subsequently, as shown in FIG. 8, using the materials and blends described in Table 1 and Table 2, concrete columns of 900 × 900 × 1800 mm were produced and the side surfaces thereof were measured objects of Examples and Comparative Examples. did. The concrete was cast in one layer, demolded at 5 days of age, and then measured at 91 days of age. Further, the mold was attached with an adhesive 15 days before placing the concrete, and after outdoor exposure was carried out for 14 days, it was used as a mold for this specimen.

Using the curing sheets 1 to 9 made of each resin composition described in Table 3 and the two types of molds described in Table 4, the effect of the linear expansion coefficient of the curing sheet on workability and curing performance A test was conducted to investigate. In the examples and comparative examples, the curing sheet was affixed to the mold by the manufacturing method of the present invention before placing, and demolded at the age of 5 days, and the curing sheet was removed at the age of 91 days. In Reference Example 1 in which only the normal form was used and no curing sheet was used, and in Reference Example 2 in which only the permeable form was used and no curing sheet was used, the mold was removed at the age of 5 days. In addition, it was as Table 5 about the linear expansion coefficient of the curing sheets 1-9.

First, when the fresh properties of the concrete used in this test were tested at the time of placing, the slump (according to JIS A 1101) was 13.5 cm, and the air amount (according to JIS A 1128) was 4.4%.

Moreover, about the concrete test body T (Examples 1-7, Comparative Examples 1-2, Reference Examples 1-2) each produced using the sheets 1-9, peeling area, neutralization depth, and surface water absorption speed | rate Was measured.

[Peeling Area] FIG. 12 and FIG. 13 show the appearance of the sheet exposed for 14 days after application. 12 (a) is a photograph of Example 2, FIG. 12 (b) is a photograph of Example 1, FIG. 13 (a) is a photograph of Comparative Example 2, and FIG. 13 (b) is a photograph of Comparative Example 1.

In addition, Table 5 and FIG. 9 show the linear expansion coefficient of the sheet and the peeled area ratio from the mold. When the linear expansion coefficient exceeded 250 μ / ° C., the peeled area ratio was 40% or more, and the sheet peeled from the mold by its own weight. Further, when the linear expansion coefficient exceeded 100 μ / ° C., wrinkles were generated on the sheet, and the wrinkles were transferred to the concrete. In this specification, the “peeling area ratio” means the surface of the curing sheet 10 affixed to the mold, for example, a portion that has not been kept in close contact with an image analysis software by photographing with a digital camera. The pixel data is binarized in lightness (black and white) at the portion where the contact is maintained and the portion where the contact is maintained, and the ratio of the number of each pixel is used as an area ratio. it can. 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.

[Neutralization depth]
Table 5 and FIG. 10 show the relationship between the linear expansion coefficient of the curing sheet and the neutralization depth. The neutralization depth was measured by exposing to an accelerated environment of 20 ° C., 60% RH, and 5% CO ₂ concentration for 28 days, according to “JIS A 1152 Concrete Neutralization Depth Measurement Method”. Up to a linear expansion coefficient of up to 80 μ / ° C., the neutralization depth was remarkably smaller than in the case of a normal mold frame or a water-permeable mold pattern, and a high curing effect was obtained regardless of the value of the linear expansion coefficient. When it exceeds 100 μ / ° C., the neutralization depth increases as the linear expansion coefficient increases, and the curing effect tends to decrease. In the case of 100 μ / ° C., the neutralization depth slightly increases, but a high curing effect is obtained. When it exceeds 120 μ / ° C., the curing effect is the same as that of the permeable girder frame, and when it exceeds 200 μ / ° C., the curing effect is not obtained as that of the normal mold.

[Surface water absorption speed]
Table 5 and FIG. 11 show the relationship between the linear expansion coefficient of the curing sheet and the surface water absorption rate. The surface water absorption rate was measured by a method of measuring the amount of water absorption for 10 minutes on the concrete surface at atmospheric pressure. Up to a linear expansion coefficient of 80 μ / ° C., regardless of the value of the linear expansion coefficient, the surface water absorption rate was remarkably smaller than in the case of a normal mold or a water-permeable mold, and a high curing effect was obtained. When it exceeds 100 μ / ° C., the larger the linear expansion coefficient, the larger the surface water absorption rate, and the curing effect tends to decrease. In the case of 100 μ / ° C., the surface water absorption rate is slightly increased, but a high curing effect is obtained. When 120 to 150 μ / ° C., a curing effect equivalent to that of a permeable girder frame was obtained, and when exceeding 250 μ / ° C., a curing effect equal to that of a normal mold was not obtained.

  From the above, it was confirmed that the curing effect is reduced in the sheet having a large linear expansion coefficient. That is, the smaller the linear expansion coefficient, the more the thermal deformation of the sheet is suppressed and the sheet curing effect can be ensured. In order to prevent a reduction in curing effect due to thermal deformation of the sheet, the thermal expansion coefficient of the sheet needs to be 100 μ / ° C. or less, and desirably 80 μ / ° C. or less.

10, 20 Curing sheet 14, 24 End 16, 26 Protrusion 30 Mold frame 40 Gum tape ST10 Mold installation process ST20 Placing process ST30 Demolding process ST40 Curing process ST50 Watering process

Claims (9)

A mold installation process for installing a mold for placing concrete;
A placing step of placing concrete in a state where a curing sheet is affixed to the inner surface of the formwork;
A demolding step of demolding the formwork after placing the concrete;
After the demolding step, leaving the curing sheet on the surface of the concrete structure, and curing the concrete structure for a predetermined period,
When installing the formwork in the formwork installation step, the end of the curing sheet attached to the inner surface of the formwork at the boundary of the formwork is folded back so as to be substantially perpendicular to the formwork. ,
In the placing step, the cured sheet is fixed by embedding the folded protrusion in the concrete when placing concrete, and the folded cured sheets are spaced apart from each other by a predetermined interval. It is characterized by
The curing sheet is a resin sheet capable of maintaining the smoothness of the surface portion of the concrete structure in which the curing sheet is left in the curing process, because at least the surface other than the end of the curing sheet is substantially smooth. A method for producing a concrete structure having a linear expansion coefficient of 100 μC or less. The method for producing a concrete structure according to claim 1, wherein a concrete surface exposed between the curing sheets arranged at a predetermined interval is covered with a tape member after the mold is removed. The method for producing a concrete structure according to claim 1 or 2 , wherein the curing sheet has a linear expansion coefficient of 80 µ / ° C or less. The manufacturing method of the concrete structure in any one of Claim 1 to 3 further equipped with the curing sheet sticking process of sticking the said curing sheet beforehand in the said mold before the said mold installation process. The method for producing a concrete structure according to any one of claims 1 to 4 , wherein the predetermined period in the curing step is 7 days or more after the mold is removed from the mold. The method for producing a concrete structure according to any one of claims 1 to 4 , wherein the predetermined period in the curing step is 28 days or more after the mold is removed. The method for producing a concrete structure according to any one of claims 1 to 4 , wherein the predetermined period in the curing step is 91 days or more after the mold is removed from the mold. The method for producing a concrete structure according to any one of claims 1 to 7 , wherein a thickness of the curing sheet is 0.1 mm or more. The method for producing a concrete structure according to any one of claims 1 to 8 , wherein the concrete is blast furnace cement concrete.