JP5382399B2 - Thermal insulation and curing method for mass concrete - Google Patents

Description

  The present invention relates to a heat curing method for preventing temperature cracks during curing of mass concrete.

  As is well known, when constructing mass concrete as a frame for civil engineering and building structures such as large underground tanks and nuclear facilities, the temperature difference between the inside and the surface of the concrete increases during hardening. As a result, tensile stress may be generated on the concrete surface, resulting in temperature cracks. As a preventive measure, for example, a method using a heat curing as shown in Patent Document 1 is widely adopted.

FIG. 5 shows an example of the case where the conventional heat curing method is applied in the construction of the bottom base 1 of a large underground tank. After the concrete is placed, the entire surface is covered with a curing material 2 having a heat retaining function. By suppressing the temperature drop on the surface, the temperature difference between the surface and the inside is reduced, thereby reducing the tensile stress on the surface and preventing temperature cracking. As the curing material 2, a mat-like material made of various heat insulating materials, foam materials such as polystyrene foam, or an air pack material having an air layer is generally used.
JP 2001-20525 A

  By the way, at the time of placing mass concrete, it is normal that a reinforcing bar or the like is raised on the surface. For example, in the construction of the bottom plate 1 of the underground tank shown in FIG. It is usual that they are constructed and started up in a state where they are closely arranged at the outer peripheral edge of the bottom board 1.

In this case, since the mat-shaped curing material 2 cannot be laid as it is on the reinforcing bar 4 or the sheath tube 5, the curing material 2 is conventionally used as disclosed in Patent Document 1. A hole for passing the reinforcing bar 4 is formed in the armor, or the curing material 2 is cut according to the arrangement of the reinforcing bar, or a curing material processed into a piece shape having an appropriate size and shape is spread between the reinforcing bars. .
Therefore, in the prior art, not only does the work of laying the curing material 2 at the bar arrangement position require much labor, time, and cost, but it is not always easy to reliably close the reinforcing bars that are densely arranged. For this reason, there is a concern that a gap is left there and the heat-retaining effect is impaired.

  In view of the above circumstances, an object of the present invention is to provide an effective and appropriate method capable of reliably performing heat insulation curing for a reinforcing bar arrangement position when constructing mass concrete.

The present invention is a heat curing method for preventing temperature cracking during curing by covering the surface with a curing material having a heat retaining function during construction of mass concrete. A bag-packing cushioning material formed by filling the bag body and enclosing air in the bag body is used as a curing material, and the curing material is provided between the reinforcing bars protruding on the surface of the placed mass concrete. It is characterized by laying down without lining up.

In the present invention, the shape and dimensions of the bag cushioning material used as the curing material may be set in advance according to the bar arrangement interval at the position where it is laid.
In addition, it is conceivable to mix a plurality of types of bagging cushioning materials having different shapes and dimensions as required.
In addition, a plurality of layers of cushioning materials used as a curing material may be laid and placed, and in that case, the packaging materials of each layer should be laid so that the joints in each layer do not overlap vertically at the same position. Is preferred.
Furthermore, it is preferable that the loose cushioning material and air can be taken in and out of the bag body as a chuck mechanism capable of opening and closing one end of the bag body in the bagging cushioning material.
Further, the bag-packing cushioning material and the mat-shaped curing material are used in combination, the bagging cushioning material is laid out between the reinforcing bars, and the mat-shaped curing material is laid in a region where the reinforcing bars are not raised. It is preferable.
In particular, it is preferable that the bag-filled cushioning material is laid out without any gap between the reinforcing bars raised on the outer peripheral edge of the bottom plate of the underground tank as the mass concrete.

According to the heat insulation and curing method for mass concrete of the present invention, a flexible bag-filled cushioning material in which a rose-shaped cushioning material is simply packed and air is enclosed in the bag is used as a curing material. Just by laying between the reinforcing bars, the concrete surface can be surely covered without gaps even at the position where the reinforcing bars are densely arranged, and the temperature reduction there can be suppressed, ensuring an excellent heat retention effect, Generation of temperature cracks can be reliably prevented.
In addition, the bag cushioning material used in the present invention is sufficiently inexpensive, and the work of laying it can be performed very easily by a simple work, so when using a conventional mat-like curing material in the past. Compared with this, it is possible to greatly reduce the labor and cost required for heat insulation.

In particular, the shape and size of the bag cushioning material used as a curing material is set in advance according to the bar spacing, and multiple types of bag cushioning materials with different shapes and dimensions are mixed and used appropriately. By doing so, it is possible to perform the work of arranging them without gaps most efficiently and reliably.
In addition, the bag cushioning material is laid over two or more layers, and at that time, the position of the joints of each layer does not overlap, so that the gap can be completely eliminated as a whole and the heat is kept. It is possible to increase the effect.

The embodiment of the heat curing method of the present invention will be described with reference to FIGS.
This embodiment is applied when constructing the bottom base 1 of the underground tank as shown in FIG. 5 as mass concrete, and covering the entire concrete surface with a curing material 2 having a heat retaining function as in the prior art. Basically, in this embodiment, the heat insulation and curing at the reinforcing bar positions of the reinforcing bars 4 and sheath tubes 5 (collectively referred to as reinforcing bars and the like) raised particularly at the outer peripheral edge are easily and reliably performed. For the purpose of carrying out, the main purpose is to use a bag cushioning material 10 as shown in FIG. 1B as a curing material, and the bag cushioning material 10 is divided into two layers as shown in FIGS. They are layered with no gaps between the reinforcing bars.
2 is an enlarged cross-sectional view of a position corresponding to the II portion in FIG. 5A, and FIGS. 3A and 3B are enlarged plan views of a position corresponding to the III portion in FIG. 5B. .

The bag cushioning material 10 used in this embodiment is a rose-shaped material that is widely used as a packing material (packing material, cushioning material, gap filling material) for protecting fragile articles, precision instruments, and the like from impact. The cushioning material 11 (see FIG. 1 (a)) is the main component, and the flexible bag 12 is filled as shown in FIG. 1 (b).
This type of rose-shaped cushioning material 11 is commercially available in various materials and forms depending on the purpose and application, but is generally a foam-molded material and has appropriate air. It is usually not only excellent in buffer performance but also excellent in heat retention (heat insulation) at the same time. Further, it is naturally a sufficiently lightweight and flexible material as a function required for the packing material, and also has elasticity that can be freely deformed and restored.

  In the present embodiment, attention is paid to excellent heat retention and flexibility, which are the characteristics of the above-described rose-shaped cushioning material 11, and it is used as a curing material. Since it is difficult and extremely inconvenient to handle the cushioning material 11 as it is as shown in FIG. 1A, in this embodiment, a predetermined amount of the cushioning material 11 is provided as shown in FIG. A flexible bag 12 having a predetermined shape and size is filled into a bag cushioning material 10 as shown in FIG. 1 (b), which is used as a curing material, as shown in FIGS. It was decided to lay out without gaps.

  Therefore, the shape and size of the bag cushioning material 10 in the present embodiment are set in advance in consideration of the bar arrangement at the position where the cushioning cushioning material 10 should be laid. Specifically, for example, as shown in FIG. 1 (b), the width dimension W in the short side direction is set to a bar spacing interval (for example, 200 mm), and the length dimension L in the long side direction is slightly longer than that. It is conceivable to form a horizontally long rectangle, or to make the length L sufficiently long to form a strip shape. The thickness dimension D may be appropriately set in consideration of the required heat retention performance. Naturally, the greater the thickness dimension D (the greater the thickness), the better the heat retention performance, but for example about 20 mm. Is preferred.

The filling amount and filling density of the rose-shaped cushioning material 11 in the bag body 12 may be set so as to obtain a desired heat retaining performance. However, if the rose-shaped cushioning material 11 is overfilled, it can be freely deformed. This is not preferable because it is damaged, and it is necessary to keep the density so as to be freely deformable depending on the bar arrangement situation.
Moreover, when filling the rose-shaped cushioning material 11 into the bag body 12, an appropriate amount of air is also sealed, so that not only the heat retaining performance by the air possessed by the rose-shaped cushioning material 11 itself but also the bag body 12 is filled. The effect of improving the heat insulation performance by the enclosed air layer is obtained. However, if air is encapsulated excessively so that the bag body 12 expands, free deformation is impaired by the air pressure.
Further, after the bag body 12 is filled with the rose cushioning material 11 and the air is sealed , the bag body 12 may be sealed in a sealed state. As a mechanism, the loose cushioning material 11 and air may be freely taken in and out, and if so, the filling amount of the loose cushioning material 11 can be increased or decreased and the amount of air filled can be adjusted as necessary. It is also possible.

Although various products marketed as packing materials can be arbitrarily adopted as the rose-shaped cushioning material 11, for example, the rose-shaped foam cushioning material disclosed in JP-A-10-29664, A buffer material made of a biodegradable resin foam can be suitably employed. In any case, this kind of loose cushioning material is not a special material and can be obtained easily and cheaply. It is harmless and does not require any special treatment when it is discarded. It can be said that it is an environmentally friendly material.
Moreover, although the raw material of the bag body 12 is also arbitrary, in addition to being a flexible thing which can be freely deformed in the state filled with the rose-shaped cushioning material 11, the temperature at the time of concrete hardening (about 60 ° C. at the maximum) It is preferable to have heat resistance that can withstand heat, strength, water resistance, and durability that can be repeatedly transferred without being inadvertently damaged when handled on-site. In particular, a simple vinyl bag made of a material such as polyethylene can be suitably used.

As described above, the bag cushioning material 10 used in the present embodiment is made of the rose cushioning material 11 and the bag body 21 that can be obtained at low cost, and the configuration thereof is also the same as that of the rose cushioning material 11. Since it is a simple one that is simply packed in the bag body 12 and sealed with an appropriate amount of air, it can be made sufficiently inexpensive by mass-producing it according to the specified standards, and compared with various conventional curing materials. There will be no significant cost increase.

And since this bagging cushioning material 10 is sufficiently flexible, it can be freely deformed according to the bar arrangement state as shown in FIG. 3 simply by laying it between closely arranged reinforcing bars. Therefore, it is possible to reliably cover the entire concrete surface without generating a large gap around the reinforcing bar, and as a result, it is possible to ensure an excellent heat retention effect and to reliably prevent the occurrence of temperature cracks. It is.
Of course, it is only necessary to lay the bag cushioning material 10 that has been manufactured in advance in a shape and size corresponding to the spacing between the reinforcing bars, so that the operation is simple and does not require any trouble or skill, as in the past. The mat-shaped curing material 2 does not require any labor to form or cut a hole for passing a reinforcing bar, and an extremely efficient operation is possible. In addition, before laying the bag-filling cushioning material 10, the water may be sprayed by spraying water on the concrete surface as usual.

  By the way, in the heat insulation curing method of this embodiment, although the bagging cushioning material 10 may be laid out over the entire surface of the placed concrete, as shown in FIGS. As in the past, a large mat-shaped curing material 2 is simply laid on the area where no reinforcing bars are set up, and the mat-shaped curing material 2 cannot be used as it is. It is practical to use the bag cushioning material 10 of the embodiment.

In addition, as shown in FIGS. 2 to 3, if the bagged curing material 10 is laid in two layers, the heat insulation thickness can be doubled compared to the case of a single layer, and the heat insulation effect accordingly. Can be increased. However, this is not necessarily the case. Depending on the degree of the required thermal insulation effect and depending on the thermal insulation performance of the bag cushioning material 10 itself, it may be a single layer or a multilayer of three or more layers. Of course it is good.
However, it is preferable to use two or more layers rather than a single layer in order to lay them out completely without gaps. In that case, the position of the joints is not overlapped between the upper layer and the lower layer by changing the arrangement in each layer. It is preferable. In other words, in the case of a single layer, or even if there are two or more layers, if the joint portions of each layer overlap, there is a concern that heat loss may occur through the joint portions and the heat retaining effect there may be impaired. For example, as shown in FIGS. 3A and 3B, the lower layers are arranged along the wall thickness direction, and the upper layers are arranged along the wall length direction (or vice versa). It is preferable to arrange the bag cushioning material 10 in such a manner that the position of the joint portion is shifted by changing the position and orientation of the bagging cushioning material 10 in order to completely eliminate the gap.

  Of course, the shape and dimensions of the bagging cushioning material 10 are basically set in advance according to the bar arrangement interval, but when the bar arrangement situation is complicated, there are various shapes, dimensions and specifications. It is also possible to prepare bagging cushioning materials and use them in various combinations. However, if the size of the bag cushioning material 10 is made too small, it will take more time to lay it out, and if too many types are used, it will become more complicated and cost will increase. It is advisable to determine the optimal specifications according to the scale and situation of the product.

FIG. 4 shows the verification test and the result about the heat retention performance of the bagging cushioning material 10 used in the present invention.
As shown in (a), a cubic mass concrete 20 having a side of 500 mm is used as a specimen, and the bottom surface and four circumferential surfaces thereof are surrounded by a heat insulating container 21 (using a urethane foam having a thickness of 50 mm), and the top surface is the same as that of the present embodiment. In the state covered with the bag packing material 10, the temperature at the center and upper surface of the mass concrete 20 at the time of curing was measured by the temperature sensor 22, and the temperature analysis was performed by FEM analysis.
The bag cushioning material 10 in this experiment has W = L = 500 mm and D = 20 mm, and is obtained by stacking two layers (total thickness 40 mm) as specimen No. 1 and three layers (total thickness 60 mm). Specimen No. 2 and 5 layers (total thickness 100 mm) were used as specimen No. 3.

  In any specimen, the center temperature and the surface temperature peak after about 40 hours, and the measurement result and analysis result of the peak temperature are shown in (b). From the results, the temperature difference between the central part and the surface was measured 2.4 deg (analyzed value 2.1 deg) for specimen No. 1 and measured 1.7 deg (analyzed value 1.7 deg) for specimen No. 2; In No. 3, the measured value was only 2.2 deg (analyzed value 1.6 deg), and no significant temperature difference occurred, and the heat retaining effect by the bagging cushioning material 10 was demonstrated.

When the heat transfer coefficient of each specimen is identified by analysis, 1.7 W / m ² ° C for specimen No. 1 and 1.4 W / m for specimen No. 2 as shown in FIGS. For m ² ° C, specimen No. 3 was 1.25 W / m ² ° C. From these results, considering that the heat transfer coefficient for ordinary curing mats is about 5.0 W / m ² ° C, and the heat transfer coefficient for foamed polystyrene + brine is about 2.0 W / m ² ° C, compared to those It was demonstrated that the curing material by the bagging cushioning material 10 exhibits an excellent heat retaining effect.

The embodiment of the heat insulation curing method of this invention is a figure which shows the bagging buffer material used as a curing material. It is sectional drawing which shows the example of installation of the bagging buffer material as a curing material. It is a top view which shows the example of installation of the bagging buffer material as a curing material. It is a figure which shows the heat retention characteristic of the bagging buffer material as a curing material. It is a figure which shows the outline | summary of the heat insulation curing method with respect to mass concrete.

Explanation of symbols

1 Bottom board (mass concrete)
2 Curing material 3 Side wall part 4 Reinforcing bar 5 Sheath tube 10 Packing cushioning material (curing material)
11 Rose cushioning material 12 Bag body 20 Mass concrete (specimen)
21 Insulated container 22 Temperature sensor

Claims (7)

A thermal curing method for preventing temperature cracking during curing by covering the surface with a curing material having a thermal insulation function during construction of mass concrete,
Filling a flexible bag body with a rose-shaped cushioning material, which is a packing material, and using a bagging cushioning material in which air is enclosed in the bag body as a curing material, the curing material is placed into mass concrete. A thermal insulation and curing method for mass concrete, characterized in that the reinforcing bars projecting on the surface of the steel are arranged without gaps between them. It is the heat insulation curing method of the mass concrete according to claim 1,
A method for heat-retaining and curing mass concrete, characterized in that the shape and dimensions of a bag cushioning material used as a curing material are set in advance according to the bar arrangement interval at the position where the cushioning material is laid. A method for heat-retaining and curing mass concrete according to claim 1 or 2,
A method for heat-retaining and curing mass concrete, wherein a plurality of types of cushioning materials having different shapes and dimensions are mixedly used as a curing material. It is the heat insulation curing method of mass concrete according to claim 1, 2, or 3,
The mass concrete is characterized by laying and laying multiple layers of cushioning materials used as a curing material, and laying the cushioning materials of each layer so that the joints in each layer do not overlap vertically at the same position Thermal insulation curing method. A method for keeping and curing a mass concrete according to claim 1, 2, 3, or 4,
  A mass concrete heat-retaining curing method characterized in that the loose cushioning material and air can be taken in and out of the bag body as a chuck mechanism capable of opening and closing one end of the bag body in the bagging cushioning material. A heat insulation curing method for mass concrete according to claim 1, 2, 3, 4 or 5,
  Combining the bag cushioning material and a mat-shaped curing material, laying the bag cushioning material between the reinforcing bars and spreading the mat-shaped curing material in an area where no reinforcing bars are set up; A heat retention curing method for mass concrete. A method for maintaining and curing a mass concrete according to claim 1, 2, 3, 4, 5 or 6,
  The mass concrete is a bottom plate of an underground tank, and the bagging cushioning material is laid out without any gap between the reinforcing bars raised on the outer peripheral edge of the bottom plate.

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