Concrete pouring method and formwork

Abstract

To accurately detect the compaction status of concrete.SOLUTION: A concrete pouring method for pouring concrete into a formwork comprises steps of applying vibration to the concrete in the formwork by a vibrator inserted into the concrete, detecting vibrations caused by the vibrator by an acceleration sensor that is in contact with the concrete through a material different from the formwork and is vibrationally separated from the formwork and that can be attached to the formwork, and detecting the compaction status of the concrete near the formwork based on the kinetic energy of the concrete calculated from the detected vibrations.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a concrete pouring method and formwork. [Background technology]

[0002] In concrete structures, in order to ensure the quality of the concrete after hardening, it is common to insert an internal vibrator (such as a vibrator) into the poured concrete to vibrate it and compact it.

[0003] Insufficient compaction of poured concrete can sometimes cause defects in concrete structures, but the compaction status of poured concrete is difficult to check visually. For this reason, methods for checking the compaction status of poured concrete in formwork are being developed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-231691 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, an acceleration sensor is attached to the outer surface of a formwork, and an internal vibrator inserted into the concrete inside the formwork measures vibrations imparted to the covering concrete in contact with the formwork using the acceleration sensor. The measured vibrations imparted to the covering concrete are then used to check the compaction status of the concrete. This technology prevents the acceleration sensor from remaining in the concrete as a foreign object and makes it possible to reuse the acceleration sensor.

[0006] However, measuring vibrations imparted to the concrete inside the formwork using an acceleration sensor attached to the outer surface of the formwork, as in Patent Document 1, does not allow for accurate measurement of the vibrations imparted to the concrete. Therefore, the technology in Patent Document 1 is unlikely to be able to accurately detect the compaction status of the concrete.

[0007] In one aspect, the present invention aims to provide a concrete pouring method and formwork that are capable of detecting the compaction status of concrete with high accuracy. [Means for solving the problem]

[0008] As a result of studying the technology of Patent Document 1, the inventors have confirmed that when the material of the formwork is changed, the compaction state of the concrete cannot be detected with high accuracy. The present invention is based on this new finding.

[0009] In one embodiment, With opposing side plates A method for pouring concrete into a formwork, comprising the steps of: applying vibration to the concrete in the formwork by a vibrator inserted into the concrete; and determining a vibration range of the vibrator when compacting the concrete. For each of the side panels, the concrete filling height and the length of the vibrating part of the vibrator are adjusted horizontally. A plurality of such devices are installed for each concrete frame, and are in contact with the concrete frame through a material different from that of the concrete frame, and are vibrationally isolated from the concrete frame and can be attached to the concrete frame. Multiple The method includes the steps of detecting vibrations caused by the vibrator using an acceleration sensor, and detecting the compaction status of the concrete near the formwork based on the kinetic energy of the concrete calculated from the detected vibrations. [Effects of the Invention]

[0010] The compaction status of concrete can be detected with high accuracy. [Brief explanation of the drawings]

[0011] [Figure 1]3 is a flowchart showing a concrete compaction method according to the first embodiment. [Figure 2] 3 is a diagram showing an example of the arrangement of a formwork and an acceleration sensor in the first embodiment. FIG. [Figure 3] 3(a) and 3(b) are diagrams for explaining the arrangement of the acceleration sensor. [Figure 4] 4(a) to 4(c) are diagrams for explaining a method for fixing the acceleration sensor to a formwork in the first embodiment. [Figure 5] 3A and 3B are diagrams for explaining vibration acceleration detected by an acceleration sensor in the first embodiment. [Figure 6] 6(a) and 6(b) are diagrams for explaining a method for fixing the acceleration sensor to a formwork in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment The first embodiment will be described below.

[0013] Fig. 1 is a flowchart showing a concrete compaction method, i.e., a concrete pouring method, according to the first embodiment. In the first embodiment, as shown in Fig. 1, an energy measurement step (S1), a pouring step (S2), a measurement step (S3), a calculation step (S4), and a comparison step (S5) are performed.

[0014] (Energy measurement process (S1)) The energy measurement step S1 is a step in which the compaction completion energy is measured in advance using a form made of the same material as the form used in the pouring step (S2) and a concrete sample of the same composition as the concrete to be poured in the pouring step (S2) or a concrete sample of similar quality. Here, the compaction completion energy is the kinetic energy required to compact the concrete to its theoretical density (to eliminate voids from the concrete). The measured compaction completion energy is stored in a computer (not shown). Alternatively, a model experiment or the like may be performed to determine the relationship between kinetic energy and concrete quality, and the compaction completion energy may be set from this relationship, or other methods may be used.

[0015] In the energy measurement step S1, acceleration sensors are installed in a formwork made of the same material as the formwork used in the concrete pouring step (S2). The acceleration sensors are installed in approximately the same positions on the formwork as they will be installed in the concrete pouring step (S2). For example, a formwork 10 as shown in FIG. 2 is used. The formwork 10 in FIG. 2 is formed by combining side panels 12A, 12B, 14, and the like. In this case, as indicated by the black circles in FIG. 2, acceleration sensors 20 are installed at predetermined intervals (e.g., 500 mm intervals) along the longitudinal direction (X-axis direction) on the outer surface (-Y side surface) of side panel 12A of the formwork 10, and at predetermined intervals (e.g., 500 mm intervals) along the height direction (Z-axis direction). That is, in this embodiment, the acceleration sensors 20 are installed at lattice points set at predetermined intervals (500 mm intervals). Furthermore, acceleration sensors 20 are installed on the outer surface (+Y side surface) of side panel 12B, similar to the side panel 12A, as indicated by the dashed circle in FIG. 2. The acceleration sensor 20 is connected to a computer (not shown), and measurement data of the vibration acceleration measured by the acceleration sensor 20 is transmitted to the computer (not shown).

[0016] The reason for adopting the above-described arrangement of the acceleration sensor 20 will now be explained. Figures 3(a) and 3(b) are schematic diagrams illustrating the construction of a concrete structure. As shown in Figures 3(a) and 3(b), during the construction of a concrete structure, the concrete filling height per layer is approximately 500 mm, and vibration compaction is performed each time using a rod-shaped vibrator (vibrator) 40. The length of the vibrating portion of the vibrator 40 is generally 400 to 500 mm, and it is inserted into concrete with a layer height of approximately 500 mm to perform compaction. In this case, the vibration of the vibrator 40 is transmitted horizontally. Therefore, to accurately measure the vibration transmitted from the vibrator 40 with the acceleration sensor 20, it is preferable to position the acceleration sensor 20 at a height approximately equal to the center of the height range where the vibrator 40 and the concrete come into contact. Therefore, it is preferable to set the vertical spacing between the acceleration sensors 20 to approximately 500 mm.

[0017] Furthermore, the effective vibration range of vibrator 40 is approximately 10 times the rod diameter. Therefore, compaction is generally performed while moving vibrator 40 in the horizontal direction (X-axis direction in the case of the formwork in FIG. 2) at intervals of approximately 500 mm. Considering the procedure for using vibrator 40, it is preferable to install acceleration sensors 20 on formwork 10 at intervals of approximately 500 mm in the horizontal direction (X-axis direction).

[0018] For the above reasons, in this embodiment, the acceleration sensors 20 are installed at grid points spaced at 500 mm intervals, as shown in Figure 2. This makes it possible for the acceleration sensors 20 to appropriately evaluate the compaction status of the entire concrete structure poured within the formwork 10.

[0019] If the acceleration sensors 20 are installed at intervals of about 500 mm, a large number of acceleration sensors will be required for the construction of a large-scale concrete structure, which may result in enormous equipment costs. Therefore, in consideration of cost-effectiveness, acceleration sensors may be installed intensively in important areas that need to be evaluated.

[0020] As shown in FIG. 4(a), the acceleration sensor 20 may be fixed to the outer surface of the side plate 12A (and 12B) using adhesive 22. Alternatively, as shown in FIG. 4(b), the acceleration sensor 20 may be sandwiched between the side plate 12A (12B) and a fastener 26, and the fastener 26 may be fixed to the side plate 12A (12B) using screws 24, thereby tightly adhering the acceleration sensor 20 to the outer surface of the side plate 12A (12B). This arrangement allows the acceleration sensor 20 to be firmly fixed to the side plate 12A (12B) and makes it easy to attach and detach the acceleration sensor 20. Alternatively, as shown in FIG. 4(c), a through-hole 30 may be formed in the side plate 12A (12B), the acceleration sensor 20 may be placed in the through-hole 30, and a fastener 28 fixed to the acceleration sensor 20 may be fixed to the side plate 12A (12B) using screws 24. In this case, the through-hole 30 in the side plate 12A (12B) serves as a mounting portion for the acceleration sensor 20.

[0021] In this first embodiment, the vibration acceleration measured by the acceleration sensor 20 is the formwork vibration itself, which is the resultant force of the formwork vibration (see symbol v1 in Figure 5) caused by the concrete vibration near the acceleration sensor 20 as the excitation force, and the vibration that has propagated through the formwork 10 and arrived there (see symbol v2 in Figure 5).

[0022] In the energy measurement process S1, a concrete sample is placed in the formwork 10 of Figure 2, and the concrete is vibrated by the vibrator 40 in the same manner as in the pouring process S2. The vibration acceleration α of the formwork 10 (measurement value of the acceleration sensor 20) is obtained when the placed concrete sample reaches a predetermined state (theoretical density).

[0023] Then, the compaction completion energy Et is calculated by substituting the compaction time t, the vibration acceleration α of the formwork over the compaction time, the vibration frequency f of the vibrator 40, and the unit volume mass ρ of the formwork into the following equation (1). Et=ρ·α 2 ·t / 4·π 2 ·f …(1) where: Et: Compaction completion energy (energy given to the formwork during compaction for t seconds) (J / L) α: Vibration acceleration of the formwork during compaction time (m / s 2 ) t: Vibration time (s) f: Frequency (s -1 ) ρ: Unit volume mass of formwork (kg / L)

[0024] In the first embodiment, in the pouring step S2, concrete is poured with the vibrator 40 positioned at a predetermined position, and then the vibrator 40 is positioned at a next position and concrete is poured. This process is repeated. Therefore, in the energy measurement step S1, with the vibrator 40 positioned, the compaction completion energy is calculated using, for example, the measurement value of the acceleration sensor 20 located closest to the vibrator 40, and the vibrator 40 is then positioned at the next position and the compaction completion energy is calculated in the same manner. In this case, the acceleration sensor 20 used to calculate the compaction completion energy and the value of the compaction completion energy are stored in the computer in association with the position of the vibrator 40.

[0025] (Pouring process (S2)) The pouring step S2 is a step of pouring concrete of the same composition as the concrete sample used in the energy measurement step S1 into the same formwork 10 as the formwork used in the energy measurement step S1. In this pouring step S2 as well, the vibrator 40 is positioned at a predetermined position, concrete is poured near the vibrator 40, the concrete is vibrated by the vibrator 40 to compact it, thereafter the vibrator 40 is positioned at the next position, concrete is poured near the vibrator 40, the concrete is vibrated by the vibrator 40 to compact it, and so on.

[0026] (Measurement process (S3)) In the measurement step S3, the acceleration sensor 20 to be used for measurement is identified according to the position of the vibrator 40, and the vibration acceleration is measured using the identified acceleration sensor 20.

[0027] (Calculation process (S4)) The calculation step S4 is a step of calculating the energy (kinetic energy) imparted to the formwork 10 by compaction for t seconds based on the vibration acceleration α and the duration t of the vibration of the formwork 10. The calculation of the energy imparted to the formwork is performed by a computer.

[0028] The energy Et based on the vibration acceleration α and the vibration duration t is calculated using the above formula (1).

[0029] Here, the materials of formwork used in concrete construction include wood (plywood), plastic (resin), steel (mostly iron), etc. For example, the unit volume weight ρw of wooden formwork is 0.5 (kg / L), the unit volume weight ρp of plastic formwork is 1.0 (kg / L), and the unit volume weight ρs of steel formwork is about 7.8 (kg / L).

[0030] In the above formula (1), the time t during which acceleration acts is 20 (s), and the vibration frequency f (the vibration frequency of a general high-frequency vibrator) is 250 (s -1 ), the energy E given to the formwork during compaction for t seconds is E≒0.002×ρ×α 2 …(2) It is expressed as:

[0031] In this case, the vibration acceleration αw of the wooden formwork, the vibration acceleration αp of the plastic formwork, and the vibration acceleration αs of the steel formwork are affected by the rigidity of the formwork, so it can be easily inferred that the following relationship holds: αw>αp>αs

[0032] As an example, let us consider the acceleration due to gravity as G (= 9.8 m / s 2 ) and αw = 3G = 29.4 (m / s 2 ), αp=2G=19.6(m / s 2), αs=1G=9.8(m / s 2 ), then, from the above equation (2), the energies Ew, Ep, and Es given to the formwork in t seconds are as follows: Ew=0.002×ρw×αw 2 =0.002×0.5×(29.4) 2 ≒0.86 (J / L) …(3) Ep=0.002×ρp×αp 2 =0.002×1.0×(19.6) 2 ≒0.77(J / L) …(4) Es=0.002×ρs×αs 2 =0.002×7.8×(9.8) 2 ≒1.50(J / L) …(5)

[0033] If the unit volume weight of concrete is substituted for ρ, the result is as follows: Ew=0.002×ρ×αw 2 =0.002×2.35×(29.4) 2 ≒4.09(J / L) …(6) Ep=0.002×ρ×αp 2 =0.002×2.35×(19.6) 2 ≒1.81(J / L) …(7) Es=0.002×ρ×αs 2 =0.002×2.35×(9.8) 2 ≒0.45(J / L) …(8)

[0034] When the unit volume weight of concrete is substituted for ρ as in the above equations (6) to (8), the calculation results are significantly different from when the unit volume weight of the formwork is substituted for ρ as in the above equations (3) to (5). Considering that the vibration acceleration actually measured by the acceleration sensor 20 of the first embodiment is the vibration acceleration of the formwork (see FIG. 5), when energy is calculated as in the above equations (6) to (8), there is a high possibility that the completion of concrete compaction cannot be accurately determined.

[0035] (Comparison process (S5)) The comparison step S5 is a step of comparing the energy calculated in the calculation step S4 with the compaction completion energy stored in the computer. In this case, the energy calculated from the measurement results of the acceleration sensor 20 closest to the position of the vibrator 40 is compared with the compaction completion energy stored in association with that acceleration sensor 20.

[0036] If the calculated energy exceeds the compaction completion energy, it is determined that the compaction of the concrete is complete, and if the calculated energy is below the compaction completion energy, it is determined that the compaction is insufficient.

[0037] As described above in detail, according to the first embodiment, the vibrator 40 inserted into the concrete vibrates the concrete in the formwork 10 (S2). The acceleration sensor 20 detachably attached to the outside of the formwork 10 detects the vibration acceleration of the vibrator 40 (S3). The compaction status of the concrete near the formwork 10 is detected based on the kinetic energy of the formwork 10 calculated from the detected vibration acceleration (S4). This allows the kinetic energy of the formwork 10 to be appropriately calculated using the vibration acceleration transmitted from the vibrator 40 to the formwork 10 via the concrete. Using this calculation result, the compaction status of the concrete poured into the formwork 10 can be accurately confirmed. Therefore, the compaction status of the concrete in the formwork 10, which cannot be visually confirmed, can be accurately confirmed, thereby preventing defects such as insufficient compaction and enabling the construction of a high-quality concrete structure. Furthermore, because the acceleration sensor 20 is installed on the outer surface of the formwork 10, the acceleration sensor 20 does not remain as a foreign object in the concrete structure. Furthermore, the acceleration sensor 20 can be used repeatedly, making it economical. Furthermore, the acceleration sensor 20 is easy to install, making it easy to work with. Furthermore, in this embodiment, the completion of concrete compaction can be determined immediately, ensuring reliable compaction work.

[0038] Furthermore, in the first embodiment, the compaction status of the concrete near the formwork 10 is detected according to the material of the formwork 10. That is, the kinetic energy of the formwork is calculated using the unit volume weight of the formwork 10, and the completion of compaction is determined based on the calculated kinetic energy. This makes it possible to determine the completion of concrete compaction more accurately than when the kinetic energy is calculated using the vibration acceleration detected by the acceleration sensor 20 provided outside the formwork 10 and the unit volume weight of the concrete (see Patent Document 1 above).

[0039] In the first embodiment, the acceleration sensor 20 is provided on both the side plates 12A and 12B of the formwork 10, but the acceleration sensor may be provided on only one of the side plates. Also, the acceleration sensor 20 may be provided on the side plate 14.

[0040] Second Embodiment The second embodiment will be described below.

[0041] In the second embodiment, the unit volume weight of concrete is used as ρ in the above equation (1), and accordingly, the method of fixing the acceleration sensor 20 to the side panels 12A, 12B of the formwork 10 is changed from that in the first embodiment.

[0042] FIG. 6(a) shows an example of a method for fixing the acceleration sensor 20 in the second embodiment. As shown in FIG. 6(a), in this second embodiment, a through-hole 30 is formed in the side panel 12A (12B), and the acceleration sensor 20 is inserted into the through-hole 30 with a vibration-isolating material 50 interposed therebetween. That is, in FIG. 6(a), the through-hole 30 serves as the mounting portion for the acceleration sensor 20. Here, the vibration-isolating material 50 can be made of, for example, rubber, resin, or a spring. In this case, the acceleration sensor 20 comes into contact with the concrete poured into the formwork 10 and detects the vibration acceleration of the concrete. However, the vibration-isolating material 50 acts to isolate the acceleration sensor 20 from the formwork 10, so the acceleration sensor 20 does not detect the vibration acceleration of the formwork 10.

[0043] Note that the method of fixing the acceleration sensor 20 to the side plates 12A, 12B may be other than that shown in Fig. 6(a), such as that shown in Fig. 6(b). As shown in Fig. 6(b), the acceleration sensor 20 may be housed in an acceleration sensor housing case 52, and with the acceleration sensor 20 inserted into the through-hole 30, the acceleration sensor housing case 52 may be fixed with screws 24 to vibration-isolating materials 54 fixed to the outer surfaces of the side plates 12A (12B). This method also allows the acceleration sensor 20 to be vibrationally isolated from the formwork 10, as in Fig. 6(a).

[0044] In the second embodiment, similarly to the first embodiment, the processing shown in Fig. 1 is performed. Below, the differences from the first embodiment among the steps shown in Fig. 1 will be described.

[0045] (Energy measurement process (S1)) In the second embodiment, as in the first embodiment, the same formwork as used in the pouring step S2 is used to pour the same concrete sample as used in the pouring step S2. The compaction completion energy Et of the concrete is calculated from the measurement results obtained at that time by the acceleration sensor 20. In this case, the compaction completion energy Et is calculated by substituting the compaction time t, the vibration acceleration α of the concrete after the compaction time has elapsed, the vibration frequency f, and the unit volume mass ρ of the concrete into the following equation (9): Et=ρ·α 2 ·t / 4·π 2 ·f …(9) where: Et: Compaction completion energy (energy received by concrete during compaction for t seconds) (J / L) α: Vibration acceleration of concrete during compaction time (m / s 2 ) t: Vibration time (s) f: Frequency (s -1 ) ρ: Unit volume mass of concrete (kg / L)

[0046] In the second embodiment, the vibration acceleration α of the concrete is measured and the compaction completion energy Et of the concrete is calculated, so the energy measurement step S1 does not have to be performed using all of the acceleration sensors 20. For example, the compaction completion energy Et of the concrete may be calculated using one or more acceleration sensors 20, and the value of the compaction completion energy used in the comparison step may be set from the calculated compaction completion energy Et.

[0047] In the second embodiment, the compaction completion energy can also be measured using a compaction energy measuring device. The compaction energy measuring device vibrates a concrete sample placed in a container until it reaches a predetermined dimension (theoretical density).

[0048] The compaction energy measuring device includes, for example, a vibration table equipped with an acceleration sensor, a control panel, a concrete sample container, a disk that follows the settlement of the concrete sample's top surface, a displacement meter that measures the disk's position, and a computer. The concrete sample container is fixed on the vibration table, which generates only vertical vibrations. The control panel has a switch that starts the computer's measurement program as soon as the motor that powers the vibration table starts rotating.

[0049] In this case, the compaction energy measuring device compacts the concrete to its theoretical density, and calculates the compaction completion energy by substituting the compaction time t, the maximum acceleration α of the vibration table, and the vibration frequency f into the following equation (10). Et=ρ·α 2 ·t / 4·π 2 ·f …(10) where: Et: Compaction completion energy (energy received by concrete during compaction for t seconds) (J / L) α: Maximum acceleration (m / s 2 ) t: Vibration time (s) f: Frequency (s -1 ) ρ: Unit volume mass of sample (concrete) (kg / L)

[0050] (Calculation process (S4)) The calculation step S4 is a step of calculating the energy received by the concrete during compaction for t seconds based on the vibration acceleration α and the duration t of the vibration of the formwork 10. The calculation of the energy received by the concrete is performed by a computer.

[0051] The energy Et based on the vibration acceleration α and the vibration duration t is calculated by the above formula (9).

[0052] In this second embodiment, the vibration acceleration of the concrete is detected using an acceleration sensor 20 that is vibrationally isolated from the formwork 10 by vibration-damping material 50 (or 54), and the concrete compaction completion energy is calculated using the unit volume mass ρ of the concrete, so that the completion of concrete compaction can be accurately determined.

[0053] In the second embodiment, the acceleration sensor 20 is fixed to the formwork 10 via the vibration-damping materials 50, 54. However, the present invention is not limited to this, and the acceleration sensor 20 may be fixed to the formwork 10 via a material different from that of the formwork 10.

[0054] In the second embodiment, the through holes 30 are formed in the side plates 12A, 12B of the formwork 10, and the acceleration sensors 20 are provided in the through holes 30. However, this is not limiting. For example, instead of the through holes 30, recesses may be formed in the side plates 12A, 12B, and the acceleration sensors 20 may be provided in the recesses. In this case, the recesses may open to the outside of the side plates 12A, 12B, or may open to the inside of the side plates 12A, 12B. If the recesses open to the outside of the side plates 12A, 12B, it is preferable that they are dug deep enough to allow the acceleration sensors 20 to accurately measure vibrations of the concrete.

[0055] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this and can be modified in various ways without departing from the spirit of the present invention. [Explanation of symbols]

[0056] 10 Formwork 20 Acceleration sensor 30 Through hole (mounting part) 40 Vibrator 50 Vibration isolation material 54 Vibration isolation material

Claims

1. A method of pouring concrete into a formwork having opposing side panels, comprising: vibrating the concrete in the formwork by a vibrator inserted into the concrete; a step of detecting vibrations caused by the vibrator using a plurality of acceleration sensors that are installed horizontally on each of the side panels of the formwork in accordance with the vibration range of the vibrator during compaction of the concrete, corresponding to the filling height of the concrete and the length of the vibrating portion of the vibrator, and that are in contact with the concrete via a material different from the formwork but are vibrationally isolated from the formwork; and and detecting the compaction status of the concrete near the formwork based on the kinetic energy of the concrete calculated from the detected vibration.

2. 2. The method for pouring concrete according to claim 1, wherein the material different from the formwork is a vibration-proof material.

3. 3. The concrete pouring method according to claim 2, wherein a through hole is formed in the formwork, and the acceleration sensor is inserted into the through hole with the vibration-damping material interposed therebetween.

4. 4. The concrete pouring method according to claim 3, wherein a plurality of the acceleration sensors are installed at lattice points at predetermined intervals in the longitudinal and height directions of the side panels constituting the formwork.

5. A concrete pouring method as described in any one of claims 1 to 4, wherein the step of detecting the compaction status of the concrete near the formwork is performed based on the kinetic energy of the concrete calculated from the detected vibration and the vibration acceleration of the concrete based on the unit volume weight of the concrete.

6. In a formwork used for pouring concrete and having opposing side panels, A formwork is inserted into the concrete and is installed horizontally on each of the side panels of the formwork in a manner corresponding to the filling height of the concrete and the length of the vibrating part of the vibrator, based on the vibration range of the vibrator when compacting the concrete, and is equipped with mounting portions that attach at least some of the multiple acceleration sensors that detect vibrations caused by the vibrator to the formwork in contact with the concrete through a material different from the formwork and vibrationally isolated from the formwork.

7. 7. The formwork according to claim 6, wherein a recess is formed in the formwork, and the mounting portion is provided in the recess.

8. The formwork according to claim 6, wherein a through hole is formed in the formwork, and the attachment portion is provided in the through hole.

9. The formwork according to claim 6, wherein a through hole is formed in the formwork, the material different from the formwork is a vibration-damping material, and the acceleration sensor is inserted into the through hole with the vibration-damping material interposed therebetween.

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