JP2015140597A - Construction method for concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for effectively utilizing heat of hydration in concrete placement.SOLUTION: A construction method for a concrete structure is a method for constructing the concrete structure by a placing joint for a plurality of blocks. An existing first block and a newly-installed second block adjacent to the first block are thermally connected together by a heat pipe, and the heat of hydration generated after concrete placement to the second block is transferred to the first block.

Description

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

  Since concrete generates heat of hydration after placement, cracks may occur due to temperature stress. As a technique for preventing cracking, “cooling” is performed to remove heat of hydration. For example, when constructing a concrete structure having a certain height, a technique has been proposed in which a first cooling pipe of a first lift and an adjacent second cooling pipe of a second lift are provided independently ( For example, Patent Document 1). In this technique, the first cooling pipe is filled with the cement material supplied into the second mold of the second lift through the upper surface of the hardened cement material of the first lift.

  Moreover, when constructing a concrete building under a cold temperature condition, a technique for preventing the water in the concrete from being frozen until it is placed and consolidated is proposed (for example, Patent Documents). 2). In this technique, the heat pipe is heated using exhaust heat supply means such as a garbage incineration plant.

JP 2013-159905 A JP-A-7-243261

  In the past, when cooling new concrete, the heat of hydration was removed without being utilized. An object of this invention is to provide the technique for utilizing effectively the heat of hydration which arises after concrete placement.

  The method for constructing a concrete structure according to the present invention is a method for constructing a concrete structure by joining a plurality of blocks. An existing first block and a new second block adjacent to the first block are thermally connected by a heat pipe, and heat of hydration generated after placing concrete on the second block is transferred to the first block.

  Thus, if the heat of hydration generated after concrete placement is transferred, the temperature difference between the first block and the second block can be reduced. Therefore, the difference in expansion coefficient due to heat between the first block and the second block can also be reduced, and the occurrence of cracks due to temperature stress can be suppressed. That is, the heat of hydration generated after the concrete is placed can be used effectively.

  Moreover, the construction method of a concrete structure heats the process of forming the 1st block provided with the 1st insertion hole for inserting a heat pipe, the 2nd insertion hole provided in a 2nd block, and a 1st insertion hole. A step of thermally connecting with a pipe and transferring the heat of hydration generated after placing the concrete to the second block to the first block. Specifically, with such a configuration, the heat of hydration generated after placing the concrete can be transferred. In addition, if the insertion hole which can insert / extract a heat pipe is provided, a heat pipe can be extracted and it can utilize in a next process.

  Further, the concrete structure is constructed by thermally connecting the third insertion hole of the third block and the heat storage means with a heat pipe, and storing the heat of hydration generated after placing the concrete on the third block in the heat storage means. And when placing concrete in the fourth block adjacent to the third block, the third insertion hole and the heat storage means are thermally connected by a heat pipe, and the heat of hydration stored in the heat storage means is third. You may make it further include the process of moving to a block. In this way, the heat of hydration generated after placing the concrete can be used effectively after it is once held in the heat storage means.

  In addition, the content of the means for solving the said subject can be combined as much as possible within the range which does not deviate from the subject and technical idea of this invention.

  ADVANTAGE OF THE INVENTION According to this invention, the technique for utilizing effectively the heat of hydration at the time of concrete placement can be provided.

It is a conceptual diagram explaining the transfer of the heat | fever using a heat pipe. It is a figure for demonstrating the structure and operating principle of a heat pipe. It is a flowchart which shows the construction method of the concrete structure concerning Embodiment 1. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 1. FIG. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 1. FIG. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 1. FIG. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 1. FIG. It is a flowchart which shows the construction method of the concrete structure which concerns on Embodiment 2. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 2. FIG. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 2. FIG. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 2. FIG. It is a figure for demonstrating the construction method of the concrete structure which concerns on Embodiment 2. FIG. It is a figure for demonstrating insertion of the heat pipe which concerns on another example.

<Embodiment 1>
In FIG. 1, the conceptual diagram explaining the transfer of the heat | fever using the heat pipe which concerns on this embodiment is shown. FIG. 1 shows a part of a procedure for placing concrete by dividing it into a plurality of blocks (also called “lifts”) and constructing a concrete structure 1 such as a bridge pier, for example. The “block” represents a unit for placing concrete by forming a mold (not shown), and the concrete structure 1 is constructed by casting a plurality of blocks.

In the example of FIG. 1, an existing block (also referred to as “first block”) 10 a and a new block (also referred to as “second block”) 10 b are illustrated. The block 10a and the block 10b are provided with an insertion hole 11a and an insertion hole 11b extending in the vertical direction for inserting the heat pipe 2, respectively. The heat pipe 2 is a metal tube that can transfer heat. In the example of FIG. 1, the length of the heat pipe 2 is such that approximately two blocks can be connected. Details of the heat pipe 2 will be described later. Further, at least the insertion hole 11b provided on the new block 10b side passes through the block 10b, and the insertion hole 11a of the block 10a and the insertion hole 11b of the block 10b exist at corresponding positions in the horizontal direction. Therefore, one heat pipe 2 can be inserted and removed from the block 10b to the block 10a.

  The insertion hole 11a and the insertion hole 11b are formed by placing a cylindrical formwork or a hollow pipe such as a metal pipe or a resin pipe in the block formwork before placing concrete. You may make it form by installation, and you may make it perforate in the concrete after hardening. Further, the blocks and heat pipes shown in FIG. 1 are schematic, and the number of insertion holes and heat pipes, the ratio of the size of each component, and the like are not limited to the example of FIG. Further, the concrete structure may include a reinforcing bar not shown.

  By the way, concrete contains cement, and the cement hydrates and generates heat (heat of hydration) in the hardening process (condensation process) after placing. The newly-constructed concrete expands as the temperature rises to a peak (for example, about 70 ° C. to 80 ° C.) in 1 to several days due to heat of hydration, and then shrinks as the temperature decreases. When concrete is handed over, cracking may occur because the existing concrete restrains the shrinking new concrete. In the present embodiment shown in FIG. 1, the existing block 10a and the new block 10b adjacent thereto are thermally connected by the heat pipe 2 to reduce the temperature difference between the block 10a and the block 10b. If it does in this way, the difference of the expansion coefficient by the heat of the block 10a and the block 10b can also be reduced, and the crack generation | occurrence | production to a concrete structure can be reduced.

  FIG. 2 is a schematic diagram showing the configuration and operating principle of the heat pipe 2. The heat pipe 2 includes a heat radiating part (condenser) 21, a heat insulating part 22, and a heat input part (evaporator) 23. For example, the heat pipe 2 is a hollow metal tube. In addition, a capillary structure (“wick”) 24 is formed of a metal mesh or the like on the inner wall of the metal tube (outside of the cross section of the inside), and the center of the metal tube is a cavity (container). The inside of the heat pipe 2 is sealed with a working fluid (also referred to as “heating medium”) that vaporizes or liquefies at a predetermined temperature, such as water or alternative chlorofluorocarbon. Moreover, the heat insulation part 22 is coat | covered with a heat insulating material, for example. When the heat input part 23 of such a heat pipe 2 is arranged in a high temperature place and the heat radiating part 21 is arranged in a low temperature place, the working fluid heated in the heat input part 23 is vaporized and the center of the heat pipe 2 is The container 25 moves to the heat radiating part 21. On the other hand, the hydraulic fluid cooled by the heat radiating unit 21 is liquefied and moves to the heat input unit 23 via the wick 24 provided on the inner wall of the heat pipe 2. In addition, the arrow of FIG. 2 represents the movement of hydraulic fluid.

  Thus, according to the heat pipe 2, heat can be transferred from the heat input portion 23 to the heat radiating portion 21 regardless of the positional height of the heat input portion 23 and the heat radiating portion 21. The configuration shown in FIG. 2 is an example, and various existing technologies can be applied to the heat pipe 2. By using the heat pipe 2, the heat medium can be circulated in the heat pipe with a pump or the air as the heat medium can be circulated in the heat pipe with a blower, and the heat can be lowered from a hot place. Can be moved to other locations. Note that the heat pipe 2 may be bent using, for example, a sheath tube. If it does in this way, it can insert also in the curved insertion hole.

FIG. 3 is a flowchart showing a method for constructing a concrete structure according to the first embodiment. Moreover, FIG. 4A to FIG. 4D is a figure for demonstrating the construction method of the concrete structure which concerns on 1st Embodiment. In FIG. 4A to FIG. 4D, one heat pipe 2 is schematically shown.

  In the present embodiment, first, the first block 10a having the insertion hole 11a is formed (FIG. 3: S1). In this step, as shown in FIG. 4A, first, concrete is driven by assembling a mold 12a for forming the block 10a and a mold 12 (or a hollow tube) 12b for forming the insertion hole 11a. The block 10a is formed. In the process shown in FIG. 4A, the insertion hole 11a is formed inside the mold 12b by placing concrete from the hopper 13 in the mold 12a. However, the first hole having the insertion hole 11a is formed by drilling in the existing concrete. One block 10a may be formed.

Next, the heat pipe 2 is inserted into the insertion hole 11a, and the first block 10a is cooled (S2). The heat pipe 2 is inserted into the insertion hole 11a, for example, and fixed on the upper outside of the mold 12a. In this step, as shown in FIG. 4B, one end (heat input portion 23) of the heat pipe 2 is inserted into the insertion hole 11a, and the other end (heat radiation portion 21) protrudes out of the insertion hole 11a. Move. That is, in the process of FIG. 4B, the heat of hydration is exchanged with the outside air to promote the cooling of the first block 10a. In the drawing, the temperature rise inside the block due to heat generation is schematically shown by gradation. The block is less likely to be cooled by outside air near the center, and the temperature becomes higher.

  Thereafter, the formwork 12a of the second block 10b adjacent to the existing first block 10a is assembled, and concrete is placed (S3). In this step, the heat pipe 2 is extracted from the insertion hole 11a, and concrete is driven in the manner of S1. And as shown to FIG. 4C, the insertion hole 11b is provided in the 2nd block 10b newly provided.

  Then, the heat pipe 2 is inserted from the insertion hole 11a to the insertion hole 11b, and the heat of hydration generated by the second block 10b is transferred to the first block 10a (S4). In the step shown in FIG. 4D, the heat pipe 2 cools the second block 10b and simultaneously heats the first block 10a. The heat exchange by the heat pipe 2 is performed until the heat of hydration generated in the block 10b is lowered to a predetermined temperature (for example, until the temperature is lowered to the same level as the outside air). At this time, you may make it measure the temperature inside the block 10a and the block 10b using the temperature measurement means which is not shown in figure.

  By thermally connecting the existing first block 10a and the newly installed second block 10b adjacent thereto by the heat pipe 2, the temperature difference between the block 10a and the block 10b can be reduced. Thereby, the difference of the expansion coefficient by the heat of the block 10a and the block 10b can also be reduced, and it can suppress that the crack by a thermal stress arises in a concrete structure. In other words, by matching the temperatures of the block 10a and the block 10b as much as possible, the elongation and shrinkage are also matched, and temperature cracks are prevented.

  Further, when succeeding the third and subsequent blocks, the same steps as S3 and S4 are repeated. At this time, the insertion hole 11a of the first block 10a is filled with grout such as mortar or cement, for example.

<Embodiment 2>
FIG. 5 is a flowchart showing a method for constructing a concrete structure according to the second embodiment. Moreover, FIG. 6A to FIG. 6D is a figure for demonstrating the construction method of the concrete structure which concerns on 2nd Embodiment. Here, differences from the first embodiment will be mainly described. In the process shown in FIG. 4B, heat of hydration generated in the first block 10a not adjacent to other blocks is exchanged with the outside air and is not used for heating or the like. In the second embodiment, the heat of hydration generated in the first block 10a by using the heat storage means 3 is used for heating in a later step.

  The heat storage means 3 uses existing technologies such as a latent heat storage method using a latent heat storage material, a sensible heat storage method using a sensible heat storage material, a chemical heat storage method using heat absorption or heat generation during a chemical reaction, and the like. Is. Specifically, ice, sodium acetate trihydrate, sodium sulfate decahydrate, calcium chloride hexahydrate, sugar alcohol, or the like can be used as the latent heat storage material. Moreover, water, a metal, concrete, a brick, etc. can be used as a sensible heat storage material. As the chemical heat storage material, magnesium hydroxide, calcium hydroxide, or the like can be used. What is necessary is just to select a heat storage material according to the temperature of the hydration heat of cement, and it is preferable that heat can be hold | maintained about several days according to the construction process of a concrete structure.

  In the present embodiment, first, concrete is put in a formwork to form the first block 10a (FIG. 5: S11). As shown in FIG. 6A, a block is formed by assembling a mold 12a for forming a block 10a and a mold (or a hollow tube) 12b for forming an insertion hole 11a, and placing concrete from a hopper 13. 10a and insertion hole 11a are formed.

  Next, the heat storage means holds the heat of hydration of the first block (S12). In this step, as shown in FIG. 6B, one end of the heat pipe 2 is inserted into the insertion hole 11a, the other end is connected to the heat storage device 3, and the heat of hydration generated in the first block 10a is transferred to the heat storage device 3. Relocate.

  Thereafter, as shown in FIG. 6C, the formwork of the second block 10b adjacent to the existing first block 10a is assembled, and concrete is placed (S13). And as shown to FIG. 6D, the thermal storage apparatus 3 and a 1st block are connected, and a 1st block is heated according to the temperature rise of the 2nd block 10b newly installed (S14). At this time, as shown in FIG. 6D, the heat storage device 3 may hold the heat of hydration generated in the block 10b.

  Even with such a configuration, the temperature difference between the block 10a and the block 10b can be reduced. Thereby, the difference of the expansion coefficient by the heat of the block 10a and the block 10b can also be reduced, and it can suppress that the crack by a thermal stress arises in a concrete structure. Also in this embodiment, by matching the temperatures of the block 10a and the block 10b as much as possible, elongation and shrinkage are also matched, and temperature cracks are prevented.

  For example, when the first block is a footing such as a bridge pier, the volume of the first block is larger than that of the second block. That is, the concrete used for the first block is more than the concrete used for the second block, and the amount of heat generated is greater in the first block. In such a case, according to the process shown in FIG. 6D, the first block can be heated with a larger amount of heat than the process shown in FIG. 4D.

  Further, as in the first embodiment, the first block 10a and the second block 10b are further connected by the heat pipe 2, and both the second block 10b and the heat storage device 3 are connected to the first block 10a. Heat may be transferred.

  In addition, when succeeding the third block and the subsequent blocks, the same steps as S13 and S14 may be repeated, or heat may be exchanged between adjacent blocks as in the first embodiment. Good. At this time, the insertion hole 11a of the first block 10a is filled with grout such as mortar or cement, for example. In the first embodiment, the heat storage device 3 may be used when the third block and subsequent blocks are succeeded.

<Others>
In the above embodiment, an example of a concrete structure that is handed over in the vertical direction is shown, but the present invention can also be applied to a concrete structure that is handed over in the horizontal direction. For example, the heat of hydration may be transferred by lining concrete of a tunnel. Moreover, you may apply to the concrete structure handed over to a perpendicular direction and a horizontal direction like a dam.

  The heat pipe may be embedded in concrete. For example, the temperature difference between the inside of the tunnel and the vicinity of the entrance / exit can be reduced by embedding a heat pipe in the lining concrete of the tunnel. If it does in this way, the temperature fall near the entrance / exit can be reduced, and frost damage can be suppressed by extension.

  Further, as shown in FIG. 7, the heat pipe 2 may have a support portion 26 that can be used as a handle at the time of insertion / extraction. Further, the heat input part (evaporation part) 23 of the heat pipe 2 may be fixed near the center (center of gravity) of the newly installed block using the support part 26. Heat near the surface of the concrete diffuses into the atmosphere, but heat stays inside the concrete, so the temperature is highest near the center of the block. As shown in FIG. 7, if the heat input portion 23 is fixed near the center of the newly installed block, heat exchange can be performed efficiently.

DESCRIPTION OF SYMBOLS 1 Concrete structure 10 (10a, 10b) Block 11 (11a, 11b) Insertion hole 12 Formwork 13 Hopper 2 Heat pipe 21 Heat radiation part (condensing part)
22 Heat insulation part 23 Heat input part (evaporation part)
24 Wick (capillary structure)
25 Container (Cavity)
26 support part 3 heat storage device

Claims (3)

A method of constructing a concrete structure by joining a plurality of blocks,
An existing first block and a new second block adjacent to the first block are thermally connected by a heat pipe, and heat of hydration generated after placing concrete on the second block is transferred to the first block. Let the construction method of the concrete structure. Forming the first block with a first insertion hole for inserting the heat pipe;
The second insertion hole provided in the second block and the first insertion hole are thermally connected by the heat pipe, and the heat of hydration generated after placing concrete on the second block is transferred to the first block. A process of
The construction method of the concrete structure of Claim 1 containing this. A step of thermally connecting the third insertion hole of the third block and the heat storage means with a heat pipe, and storing heat of hydration generated after placing the concrete on the third block in the heat storage means;
When placing concrete in the fourth block adjacent to the third block, the third insertion hole and the heat storage means are thermally connected by a heat pipe, and the heat of hydration stored in the heat storage means is Transferring to 3 blocks;
The method for constructing a concrete structure according to claim 2, further comprising:

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