JP2009209558A - Construction method for high strength concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method for high strength concrete, simply and securely performing curing for the placed high strength concrete. <P>SOLUTION: A column 100, for example, is constructed by this construction method for a high strength concrete. Firstly, the high strength concrete is placed in a space 10a' where a bar material 20 or a pipe material 30 exits. The surface of the high strength concrete serves as a construction joint surface. In this case, the bar material 20 or the pipe material 30 is projected from the construction joint surface. Subsequently, foam 310 is disposed on the construction joint surface. After that, concrete is placed on the upside of the construction joint surface. Thus, joining of successive pours of high strength concrete is performed. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for constructing high-strength concrete.

  When constructing a high-rise building, first, a formwork is set so as to surround the main reinforcement of the building, and then concrete is placed in the space formed by the formwork. Concrete placement is performed while casting in the vertical direction. The main reinforcement is finally buried in the concrete.

  Here, since the cast concrete is exposed at the joint surface formed at the time of the joint, the concrete is dried. Therefore, in order to prevent drying, the concrete surface is covered until the concrete hardens (curing). As covering the concrete surface, an evaporation suppression film (for example, refer to Patent Document 1) such as synthetic resin emulsion and synthetic rubber latex, and a curing sheet have been proposed.

By the way, in recent years, high-strength concrete (concrete having a design standard strength of 37 N / mm ² or more) whose strength is higher than that of ordinary concrete is often used as a structural frame material for high-rise buildings.
JP 63-134752 A

  However, the main reinforcements embedded in the concrete partially reduce the thickness of the concrete (cross-sectional defect). For this reason, cracks are likely to occur in concrete, particularly between main bars. Depending on the size and number of cracks, there is a possibility of structural defects in the building.

  Further, when the concrete is high-strength concrete, the amount of bleeding water is less than that of ordinary concrete. For this reason, the surface of high-strength concrete is easier to dry than ordinary concrete. Due to this drying, stiffness (false condensation) occurs on the surface of high-strength concrete immediately after placing. Moreover, plastic cracks are likely to occur in high-strength concrete due to surface drying (including stiffness). Therefore, when high-strength concrete is cast, it is necessary to perform curing well.

  Further, although the main bars of the building are finally buried in the concrete, they are projected from the joint surface when jointed. It is very troublesome and troublesome to arrange the evaporation suppression film and the curing sheet so as to avoid the protruding main streak. When a specific example is given, when arrange | positioning a curing sheet according to the protruding main reinforcement, it is necessary to cut a curing sheet into strip shape, for example, and to spread the cut curing sheet separately.

  This invention is made | formed in view of the above subjects, The objective is providing the construction method of the high strength concrete which can perform the curing of the cast high strength concrete simply and firmly. There is.

  In order to achieve this object, the high-strength concrete construction method of the present invention includes a step of placing high-strength concrete in advance in a space where the reinforcing material or equipment material exists, and the reinforcing material or equipment material protrudes. The method includes the steps of disposing foam on the joint surface of the high-strength concrete, and performing a subsequent placement of the concrete on the joint surface.

  According to such a high-strength concrete construction method, the joint surface is covered with foam, so that the high-strength concrete can be cured. Here, since the foam easily surrounds the periphery of the reinforcing material or the equipment material protruding from the joint surface, the curing of the high-strength concrete can be performed easily and firmly.

In this high-strength concrete construction method, it is desirable that the foam is disposed on the joint surface immediately after the high-strength concrete is placed in advance.
According to such a construction method of high-strength concrete, drying of high-strength concrete, particularly surface stiffness can be more reliably prevented.

Such a high-strength concrete construction method, wherein the foam is injected between a reinforcing material or equipment material and another reinforcing material or equipment material using an injection means, whereby the joint surface It is desirable to be arranged in
According to such a high-strength concrete construction method, since the injection means is used, foam is applied to a narrow space that is difficult to access, such as between a certain reinforcing material or equipment and another reinforcing material or equipment. Can be easily arranged.

In such a high-strength concrete construction method, it is desirable that the foam naturally disappears after being placed on the joint surface.
According to such a high-strength concrete construction method, it is possible to eliminate the need to remove foam. For this reason, it does not take time.

In this high-strength concrete construction method, the foam is so thick that the moisturizing of the joint surface by the foam is maintained until the previously placed high-strength concrete starts to solidify. In addition, it is desirable to be disposed on the joint surface.
According to such a high-strength concrete construction method, it is possible to reliably prevent the high-strength concrete from being dried (including surface stiffness) before the previously placed high-strength concrete starts to solidify.

In this high strength concrete construction method, the foam is preferably white.
According to such a high-strength concrete construction method, white foam reflects irradiated sunlight, so that an increase in the surface temperature of the high-strength concrete can be suppressed. Thereby, drying of high strength concrete can be prevented more reliably.

In this construction method of high-strength concrete, it is desirable that the foam is generated using a foaming agent that is a raw material of foamed mortar.
According to such high-strength concrete construction method, since the foaming agent that is the element of foam is the raw material of the foamed mortar, it comes into contact with the high-strength concrete that has been cast in advance or the concrete that has been cast in the subsequent process. However, it does not have an adverse effect on the concrete. For this reason, it is possible to exhibit (maintain) the good properties of concrete.

  According to the construction method for high-strength concrete of the present invention, when the high-strength concrete is cast, curing of the placed high-strength concrete can be performed easily and firmly.

  Hereinafter, the construction method of high-strength concrete as one embodiment of the present invention will be described based on the drawings.

  FIG. 1 is a perspective view showing an external appearance of a pillar as a building constructed by a high-strength concrete construction method according to an embodiment of the present invention. FIG. 2 is a flowchart (process diagram) showing a construction procedure when constructing a pillar (building) as shown in FIG. FIG. 3 is a perspective view showing a state when the formwork is installed in step S20 of FIG. FIG. 4 is a cross-sectional view showing a state when foam is placed on the surface of the high-strength concrete placed in step S30 of FIG. FIG. 5 is a perspective view showing an external appearance of a pillar (building) constructed through the processes of steps S10 to S50 in FIG.

  The construction method for high-strength concrete according to the present embodiment can be performed when building a building such as a column, a beam, a foundation, or a wall while casting high-strength concrete. In the following description, the case where the pillar 100 as shown in FIG. 1 is constructed will be described as an example. As shown in FIG. 1, the pillar 100 includes a lower concrete 10a and an upper concrete 10b. The pillar 100 is constructed by passing high-strength concrete in the vertical direction. For this reason, the upper concrete 10b is arrange | positioned above the joint surface which makes the top end surface of the lower concrete 10a.

  Next, a construction procedure for constructing the pillar 100 shown in FIG. 1 will be described focusing on the joining of high-strength concrete.

  As shown in FIG. 2, first, reinforcement reinforcement arranged on the column 100 and piping of equipment material are performed (step S10). The reinforcing material is, for example, a steel rod 20 (see FIGS. 3 to 5), and a plurality of reinforcing materials are mainly arranged along the vertical direction of the pillar 100. Therefore, the bar 20 is a main bar of the column 100. Moreover, the wire 21 is also arrange | positioned around the some rod 20 as shown in FIGS. The wire rod 21 functions as a secondary bar for the main bar, which is also an example of a reinforcing material. The equipment material is, for example, a hollow pipe material 30 (see FIG. 3).

Next, it installs so that the some formwork 200 for forming the lower concrete 10a of the pillar 100 may be assembled (step S20). As shown in FIG. 3, the bar 20 and the pipe 30 are present in the space surrounded by the installed formwork 200. Then, high-strength concrete is placed in a space 10a ′ (see FIG. 3) up to a preset top end level in a space where the bar 20 and the pipe material 30 exist (step S30). The design standard strength of high-strength concrete is, for example, 60 N / mm ² . And the surface (top end face) of the high-strength concrete placed in this way becomes a joint surface.

  Subsequently, as shown in FIG. 4, the foam 310 is disposed on the surface of the placed high-strength concrete, that is, the joining surface (step S40). It is preferable to arrange the foam 310 immediately after placing high-strength concrete.

  Here, the bar material 20 and the pipe material 30 protrude from the surface of the high-strength concrete. However, since the foam 310 arranged here is indefinite, it can easily surround the bar 20 and the pipe 30. For this reason, the foam 310 covers the entire surface (joint surface) of the high-strength concrete and keeps the moisture. Thereby, curing of high-strength concrete is performed. Moreover, the foam 310 comprises an air layer. The air layer has a high heat insulation effect. For this reason, curing of high-strength concrete can be performed in an appropriate environment.

  Further, in the present embodiment, when the foam 310 is arranged, the foaming machine 300, part of which is shown in FIG. The foaming machine 300 generates a uniform foam 310 by mixing and stirring a foaming agent that is a base of the foam 310 and a gas (for example, air) at a predetermined ratio. At this time, since the volume of the foaming agent increases, the amount of foaming agent used may be small. Then, as shown in FIG. 4, the discharge port 300a (nozzle) at the tip of the hose of the foaming machine 300 is brought near the bar 20 and the pipe material 30 and in the vicinity of the joining surface, and foam is discharged from the discharge port 300a. 310 is discharged. Thereby, the foam 310 is injected between the bar 20 and the bar 20 or between the bar 20 and the pipe 30. Here, the thickness of the foam 310 arrange | positioned on a high-strength concrete surface is adjusted according to the foam retention time mentioned later. In the present embodiment, the discharge amount of the foam 310 is adjusted so that the thickness of the foam 310 is 40 mm.

  As the foaming agent used as the base of the foam 310, a foaming agent having a surfactant as a main component diluted with a predetermined solvent, for example, 100 times is used. As the foaming agent, it is preferable to use a foaming agent used as a raw material for foaming mortar. Examples of such foaming agents include hydrocarbon surfactants (for example, polyoxyethylene alkyl ether sulfate ester salts) as main components, and various cellulose derivatives, polyvinyl alcohols, aliphatic alcohols, water And those using a combination of a conductive polymer and the like. By using such a foam mortar raw material as a foaming agent, even if the foam 310 (or the foaming agent remaining after the foam 310 spontaneously disappears) contacts the concrete before solidification or after solidification, It does not have an adverse effect on it. For this reason, it is possible to exhibit (maintain) the good properties of concrete. In the present embodiment, the foam 310 is white by using the foaming agent as described above.

  Then, the foam 310 is left on the surface of the placed high-strength concrete, for example, for 20 hours (step S50). During this standing, solidification (condensation) of high-strength concrete proceeds. In addition, the time (starting time) at which the high-strength concrete starts to set is 6 to 8 hours after the mixing of the raw materials is started. Therefore, by setting the high-strength concrete and leaving it for 6 to 8 hours, the setting of the high-strength concrete is surely found.

  In addition, during this standing, the foam 310 gradually disappears naturally, and its thickness gradually decreases. Eventually, the foam 310 disappears completely spontaneously. Here, in order to maintain the moisture retention of the high-strength concrete by the foam 310 for a sufficient time, the time until the foam 310 completely disappears (hereinafter referred to as “foam retention time”) is the above-described high level. It is preferable that the time required for firmly setting the high-strength concrete (6 to 8 hours) is approximately the same as or longer than that required. By the way, the foam holding time can be adjusted by adjusting the thickness of the foam 310. Therefore, in the present embodiment, when the foam 310 is disposed, the thickness of the foam 310 is set to, for example, 40 mm or more so that the foam retention time of 6 to 8 hours is secured.

  Thereafter, when the natural disappearance of the foam 310 and the condensation of the high-strength concrete are confirmed, the operator determines whether or not to perform further joining (formation of another joining surface) (step S60). Normally, whether or not to perform further joining is known before the start of construction. Therefore, here, it is confirmed whether or not there is a subsequent joining operation.

  If further joining is necessary (YES in step S60), the operations in steps S20 to S50 are repeated. In the present embodiment, in order to construct the upper concrete 10b, high strength concrete is cast. Prior to the joining, if necessary, the formwork 200 may be removed, further reinforcing, or further piping. FIG. 5 shows a state after the formwork 200 used for constructing the lower concrete 10a has been removed and before the formwork for forming the upper concrete 10b is installed. . As shown in FIG. 5, the foam 310 has disappeared naturally.

  On the other hand, if no further joining is necessary (NO in step S60), final placement is performed (step S70). In this embodiment, although not shown, high-strength concrete is placed further above the upper concrete 10b. Thereby, the bar 20 and the pipe 30 which protrude from the joint surface, and the wire 21 are embed | buried. In addition, according to the smoothness requested | required of the surface of the finally laid high-strength concrete, you may perform leveling and a iron holding | suppressing. Thereafter, the unnecessary formwork 200 and the like are removed (step S80). And this process is completed. In this way, the pillar 100 (FIG. 1) in which the bar 20, the wire 21, and the pipe 30 are embedded is constructed.

  According to the construction method of the high strength concrete of this embodiment, the foam 310 is arrange | positioned on the surface (joining surface) of the cast high strength concrete (step S40). With this foam 310, the high-strength concrete is cured by covering the joint surface and moisturizing the high-strength concrete (step S50). Here, the foam 310 easily surrounds the bar 20 and the pipe 30 that protrude from the joining surface. For this reason, curing of high-strength concrete can be performed easily and firmly. Specifically, drying (including stiffness) of the surface of high-strength concrete can be prevented, and as a result, the occurrence of plastic cracks can be suppressed.

  By the way, since the bar material 20 and the pipe material 30 are embed | buried in high strength concrete, it becomes a cross-sectional defect | deletion of high strength concrete. However, according to the present embodiment, since the curing of the high-strength concrete is performed firmly, the occurrence of cracks due to the cross-sectional defect can also be suppressed.

  Moreover, drying of high strength concrete can be reliably prevented by arranging the foam 310 immediately after placing high strength concrete as in the present embodiment. In particular, the occurrence of surface stiffness that occurs immediately after placing high-strength concrete can be suppressed.

  Moreover, in order to arrange the foam 310, the foaming machine 300 is used. For this reason, foam generation work becomes simple. Moreover, since the foaming machine 300 is provided with the hose which has the discharge outlet 300a, foam arrangement | positioning work is easy. In particular, in the example shown in FIG. 4, due to the plurality of bars 20 and the wires 21, it becomes difficult for the hands to enter between the bars 20 and 20 or between the bars 20 and the pipe 30. However, by using the foaming machine 300, even in such a narrow space, it is possible to easily inject the foam 310 between the bar members 20 or between the bar member 20 and the pipe member 30. .

  Furthermore, the foam 310 naturally disappears after being disposed on the joint surface (step S50). For this reason, it is not necessary to remove the foam 310 from the surface of the high-strength concrete. In addition, it replaces with the foam 310, and when a curing sheet and an evaporation suppression film | membrane are arrange | positioned like the past, it is necessary to remove. For this reason, in this embodiment, it does not take time and effort.

  Further, in the above-described embodiment, by adjusting the thickness of the foam 310 when the foam 310 is disposed, the foam retention time is approximately equal to the time required until the above-described setting of the high-strength concrete is reliably observed. It is adjusted to be the same or longer. In other words, the foam 310 is arranged on the joining surface so that the foamed 310 has a thickness that keeps the moisture retention of the joining surface by the foam 310 until the high-strength concrete placed starts to set. Thereby, the moisture retention of the high-strength concrete by the foam 310 can be maintained over sufficient time. For this reason, drying of high-strength concrete (including surface stiffness) can be reliably prevented.

  Moreover, in embodiment mentioned above, since the foam 310 is white, the sunlight irradiated toward the surface of high intensity | strength concrete can be reflected with the foam 310. FIG. For this reason, the raise of the surface temperature of high-strength concrete can be suppressed. Thereby, drying of high strength concrete can be prevented more reliably. In addition, when it is difficult to irradiate the surface of high-strength concrete with sunlight, it is not necessary to prepare a white thing as the foam 310. That is, the foam 310 may not be white.

  In the embodiment described above, the foaming machine 300 is used to generate the foam 310. The foaming machine 300 is preferably equipped with an ejection device. By using the foaming machine 300 with the ejection device, the foam 310 can be ejected. Thereby, it is not necessary to bring the supply port 300a close to the surface of the high-strength concrete, and the foam arrangement work becomes easier. In addition, when it is desired to reliably arrange the foam 310 in the space between the bar member 20 and the pipe member 30, it is only necessary to lower the jet pressure by the jet device and bring the supply port 300a closer to the surface of the high-strength concrete.

  Alternatively, the foaming machine 300 may not be used to generate the foam 310. When not using the foaming machine 300, the foam 310 is produced | generated by stirring the liquid used as the raw material of the foam 310 with air using a hand mixer etc. in a container. The foam 310 can be arranged by scooping from the container with a shovel or by tilting the container.

  It should be noted that the time required for reliably setting the high-strength concrete depends on the composition of the high-strength concrete, the environment during construction (for example, temperature and humidity), the presence or absence of sunshine, and the like. Therefore, it is preferable to appropriately adjust the thickness of the foam 310 when the foam 310 is disposed in accordance with the time required until the setting of the high-strength concrete is reliably observed. Moreover, in embodiment mentioned above, although foam holding time was adjusted by adjusting the thickness of the foam 310, it becomes the dilution rate when diluting the foaming agent used as the base of the foam 310, and the base of the foam 310 You may adjust by adjusting the component of a foaming agent.

Moreover, in embodiment mentioned above, hydrocarbon surfactant is the main component as a foaming agent (element of foam 310), and various cellulose derivatives, polyvinyl alcohol, aliphatic alcohol, water-soluble polymer, etc. as a bubble stabilizer. It was assumed that the same was used. Here, examples of the hydrocarbon-based surfactant include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Anionic surfactants that can be suitably used are known ones such as RCOONa, etc .: carboxylate, ROSO ₃ Na, etc .: sulfate ester salt, RSO ₃ Na, etc .: sulfonate, etc. Higher fatty acid salt, polyoxyethylene alkyl ether carboxylate, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt (described above), alkylbenzene sulfonate, alkyl sulfonate, alpha olefin sulfonate, N-acyl Alkyl taurine salts, sulfosuccinates, polyoxyethylene lauryl ether phosphoric acid and the like can be mentioned.

  Moreover, it may replace with the said foaming agent and may use another foaming agent. For example, you may use what used protein surfactant as a main component and also used iron salt, water-soluble polymer, etc. together. Here, examples of the protein surfactant include keratin hydrolyzate (keratin hydrolyzed protein), collagen hydrolyzate and the like. Furthermore, the element of the foam 310 is not limited to the foaming agent. Any material may be used as long as it is a foaming material and does not adversely affect concrete such as high-strength concrete.

  In the above-described embodiment, high-strength concrete is placed (preceding placement) to construct the lower concrete 10a, and then high-strength concrete is placed (follow-up placement) above the lower concrete 10a. . However, the concrete to be placed downstream may be ordinary concrete. Similarly, what is finally placed may be high-strength concrete or ordinary concrete.

  Moreover, although embodiment mentioned above demonstrated the case where the pillar 100 was mainly constructed | assembled as (a part of) a building, the above-mentioned description demonstrated buildings other than the pillar 100, for example, a beam, a foundation, or a wall. It can also be applied to the case of construction.

  In the above-described embodiment, the reinforcing material is the rod 20 or the wire 21, but may be other materials, for example, H-shaped steel. Moreover, although the equipment material is the pipe material 30, it is not limited to the pipe material 30 and is not limited to a single material.

  The above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

It is a perspective view which shows the external appearance of the pillar as a building constructed | assembled by the construction method of the high strength concrete which concerns on embodiment of this invention. It is a flowchart (process drawing) which shows the construction procedure when constructing a pillar (building) as shown in FIG. It is a perspective view which shows a state when a formwork is installed in step S20 of FIG. It is sectional drawing which shows a state when arrange | positioning foam on the surface of the high-strength concrete laid in step S30 of FIG. It is a perspective view which shows the external appearance of the pillar (building) constructed | assembled through the process of step S10-S50 of FIG.

Explanation of symbols

10a lower concrete, 10a 'space, 10b upper concrete,
20 bar, 21 wire, 30 pipe, 100 pillar, 200 formwork,
300 Foaming machine, 300a Discharge port (nozzle), 310 Foam

Claims (7)

A step of placing high-strength concrete in advance in a space where a reinforcing material or equipment material exists;
Arranging foam on the joint surface of the high-strength concrete from which the reinforcing material or equipment material protrudes;
A step of casting concrete over the joining surface and joining it,
A high-strength concrete construction method characterized by comprising:   2. The construction method for high-strength concrete according to claim 1, wherein the foam is disposed on the joint surface immediately after the high-strength concrete is placed in advance.   The foam is arranged on the joint surface by being injected between a certain reinforcing material or equipment and another reinforcing material or equipment using an injection means. The construction method of the high strength concrete of Claim 1 or Claim 2.   The construction method for high-strength concrete according to any one of claims 1 to 3, wherein the foam naturally disappears after being disposed on the joint surface.   The foam is disposed on the joint surface so that the foam is kept thick until the high-strength concrete previously placed starts solidification, and the moisture retention of the joint surface by the foam is maintained. The construction method of the high strength concrete of any one of Claims 1 thru | or 4 characterized by these.   The construction method for high-strength concrete according to any one of claims 1 to 5, wherein the foam is white.   The construction method for high-strength concrete according to any one of claims 1 to 6, wherein the foam is generated using a foaming agent that is a raw material of foamed mortar.

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