JP7543083B2 - How to determine the concrete construction method - Google Patents

Description

The present invention relates to a method for determining a concrete construction method.

During concrete pouring work, a vibrator is used to compact the concrete. For example, Non-Patent Document 1 describes a method for evaluating the degree of compaction of concrete using the air permeability coefficient. Patent Document 1 describes a method for judging the surface quality of concrete based on color image data.

Liang, Jun., Arai, Hiroyuki, Sakamoto, Jun., Matsumoto, Jun., Kuroba, Yoichiro, Harayama, Yukitoshi, Matsuo, Ken, "Study on acceleration measurement method for evaluation of compaction of dam concrete", Taisei Corporation Technology Center Report No. 46 (2013), pp. 14-1 to 14-4

JP 2016-42069 A

However, before concrete is placed at a construction site, it is necessary to determine an appropriate concrete placement method. When using the method of Non-Patent Document 1 to determine the concrete placement method, it takes about two months after demolding because there is an upper limit to the surface moisture at the time of measurement (measurements cannot be made unless the concrete is dry). In addition, when using the method of Patent Document 1, there is a possibility that the evaluation value of the concrete surface quality will vary due to the influence of lighting or light rays, and the uneven color of the concrete itself. In other words, when using the method of Patent Document 1, there is a possibility that the quality of the concrete placed at the construction site will be lower than predicted.

The present disclosure has been made in consideration of the above problems, and aims to provide a method for determining a concrete construction method that can quickly determine a construction method for forming high-quality concrete.

In order to achieve the above object, a method for determining a concrete construction method according to one embodiment of the present disclosure includes a model formation step of forming a model concrete by pouring concrete into a formwork and compacting it with a vibrator inserted into a predetermined location, a surface roughness measurement step of measuring the surface roughness of multiple parts of the model concrete at different distances from the insertion position of the vibrator using a 3D scanner after removing the formwork, a compressive strength measurement step of measuring the compressive strength of multiple parts at different distances from the insertion position of the vibrator through a test using a portion of the model concrete, and a construction method determination step of determining the insertion interval of the vibrator when constructing the concrete at a construction site based on the distance from the insertion position of the vibrator to a part of the model concrete that meets the predetermined required levels for both the surface roughness and the compressive strength.

As a preferred embodiment of the method for determining a concrete construction method, in the model formation step, when compacting is performed by the vibrator, sensors are placed on multiple parts of the surface of the concrete that are at different distances from the insertion position of the vibrator to detect vibrations.

The method of determining a concrete construction method disclosed herein allows for the rapid determination of a construction method for forming high-quality concrete.

FIG. 1 is a flowchart showing a method for determining a concrete construction method according to the present embodiment. FIG. 2 is a perspective view showing a model of the present embodiment. FIG. 3 is a plan view showing a model of the present embodiment. FIG. 4 is a schematic diagram of a concrete surface for explaining surface roughness. FIG. 5 is a graph showing the relationship between the distance from the vibrator and the compressive strength.

The present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the form for carrying out the present invention (hereinafter referred to as the embodiment). Furthermore, the components in the following embodiment include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiment can be combined as appropriate.

(Embodiment)
Fig. 1 is a flow chart showing a method for determining a concrete construction method according to the present embodiment. The method for determining a concrete construction method according to the present embodiment is targeted at concrete that has a required strength when compacted by a vibrator. As shown in Fig. 1, the method for determining a concrete construction method according to the present embodiment includes a model forming step S1, a surface roughness measuring step S2, a compressive strength measuring step S3, and a construction method determining step S4.

Figure 2 is a schematic perspective view of a model of this embodiment. Figure 3 is a schematic plan view of a model of this embodiment. The dimensions shown in Figures 1 and 2 are in mm.

In the model formation step S1, as shown in Figures 1 and 2, concrete 1 is poured into a formwork 2, and compacted by a vibrator 4 inserted at a predetermined location to form a model concrete 9. The formwork 2 is arranged so as to form a rectangular parallelepiped space inside. A cushioning material 3 is provided inside the formwork 2. The cushioning material 3 is, for example, extruded polystyrene foam. The cushioning material 3 is not necessarily required.

The concrete 1 poured into the formwork 2 forms a rectangular parallelepiped shape along the inner wall of the buffer material 3. After a predetermined amount of concrete 1 is poured into the formwork 2, a vibrator 4 is inserted from the surface of the concrete 1. The vibrator 4 is inserted only at one predetermined location in the concrete 1 and is not moved horizontally. The vibrator 4 applies vibrations to the inside of the concrete 1. For example, the vibrator 4 is a rod-shaped device with a diameter of 50 mm. For example, the vibrator 4 applies vibrations to the concrete 1 for 15 seconds. The vibrator 4 compacts the concrete 1. After compaction, the concrete 1 is cured for a predetermined time to harden. The hardened concrete 1 is the model concrete 9.

As shown in FIG. 3, in the model forming step S1, when compaction is performed by the vibrator 4, multiple sensors 5 are placed on the surface of the concrete 1. The sensors 5 detect vibrations. The sensors 5 are placed at multiple locations inside the concrete 1 at different distances from the insertion position of the vibrator 4. It is more preferable that the sensors 5 are placed inside the concrete 1 at the same horizontal height as the transducer of the vibrator 4 (half the height of the model concrete 9). In this embodiment, eight sensors 5 are placed on the same line as shown in FIG. 3. The eight sensors 5 are placed at equal intervals (125 mm intervals). The distance from the sensor 5 closest to the vibrator 4 to the vibrator 4 is 125 mm. With the multiple sensors 5 placed on the surface of the concrete 1, compaction is performed by the vibrator 4. The vibration data detected by each sensor 5 is stored in, for example, a storage device. Note that the number of sensors 5 placed, the intervals between the sensors 5, and the distance from the vibrator 4 to the nearest sensor 5 are not limited to those described above and are not particularly limited.

After the model concrete 9 is formed in the model formation step S1, the formwork 2 and the buffer material 3 are removed. This exposes the side of the model concrete 9.

Figure 4 is a schematic diagram of a concrete surface to explain surface roughness. In the surface roughness measurement step S2, after removing the formwork 2, the surface roughness of the model concrete 9 is measured by a 3D scanner at multiple parts at different distances from the insertion position of the vibrator 4. The 3D scanner is a device that detects surface irregularities by irradiating the model concrete 9 with, for example, a laser, and digitizes the shape of the irradiated area. The surface roughness measurement step S2 can be performed the day after compaction by the vibrator 4. For example, the surface roughness of the side of the model concrete 9 (the surface that was in contact with the buffer material 3, the right side surface or the left side surface in Figure 3) is measured. Hereinafter, the side of the model concrete 9 is referred to as the formwork surface.

Specifically, the surface roughness is calculated for a plurality of regions of the formwork surface that are different in distance from the vibrator 4. FIG. 4 shows one region of the formwork surface. The 3D scanner measures the distances (y ₁ , y ₂ , y ₃ , y ₄ , y ₅ , ..., _yn ) from the measurement reference surface R at a plurality of points in one region of the formwork surface. The surface roughness in one region may be quantified, for example, as the arithmetic mean roughness calculated by the following formula (1), or as the root mean square roughness calculated by the following formula (2). The quality of concrete tends to be higher when the surface is smooth, so it is desirable for the surface roughness to be small.

The method for quantifying the surface roughness does not have to be the method described above and is not particularly limited. The surface roughness may be a line roughness parameter or an areal roughness parameter.

In the compressive strength measurement step S3, a test is performed using a portion of the model concrete 9 to measure the compressive strength of multiple portions at different distances from the insertion position of the vibrator 4. The compressive strength measurement step S3 can be performed the day after compaction by the vibrator 4, but it is more preferable to perform it one week after compaction by the vibrator 4. The compressive strength measurement step S3 may be performed before the surface roughness measurement step S2. There is no particular restriction on the order of the compressive strength measurement step S3 and the surface roughness measurement step S2.

For example, parts of the model concrete 9 are excised as cores (cylindrical test specimens) at positions 125 mm, 250 mm, 375 mm, 500 mm, 625 mm, 750 mm, 875 mm, and 1000 mm away from the insertion position of the vibrator 4. A compressive strength test is performed on the eight cores, and the relationship between the distance from the insertion position of the vibrator 4 and the compressive strength of the model concrete 9 is recorded. The compressive strength of the model concrete 9 may be estimated from the measurement value obtained by a test hammer.

Figure 5 is a graph showing the relationship between the distance from the vibrator and the compressive strength. As shown in Figure 5, the compressive strength of the model concrete 9 decreases the further away from the vibrator 4. Within 1000 mm from the vibrator 4, the compressive strength of the model concrete 9 exceeds the design strength and the in-situ strength. The design strength is the strength used in structural calculations. The in-situ strength is the strength that actually appears when compaction is performed in the in-situ environment of the structure for a longer time than in the test using the model concrete 9.

In the construction method determination step S4, the insertion interval of the vibrator 4 when constructing the concrete 1 at the construction site is determined. The insertion interval of the vibrator 4 is determined based on the distance from the insertion position of the vibrator 4 in the model formation step S1 to a portion of the model concrete 9 that satisfies the specified required levels for both surface roughness and compressive strength. For example, if the minimum distance between the portion of the model concrete 9 whose surface roughness is equal to or less than the first threshold value and whose compressive strength is equal to or greater than the second threshold value and the insertion position of the vibrator 4 is X mm, the insertion interval of the vibrator 4 when constructing at the construction site is determined to be X mm or less.

An example of the second threshold value mentioned above is the in-situ strength of concrete 1. As shown in FIG. 5, the compressive strength of the model concrete 9 in this embodiment exceeds the in-situ strength when the distance from the vibrator 4 is 625 mm. For this reason, if the surface roughness at a position 625 mm away from the vibrator 4 is equal to or less than the first threshold value, the insertion interval of the vibrator 4 when performing construction at the construction site is determined to be equal to or less than 625 mm. If the position at which the surface roughness is equal to or less than the first threshold value is equal to or less than Y mm away from the vibrator 4, the insertion interval of the vibrator 4 when performing construction at the construction site is determined to be equal to or less than Y mm.

In addition, in the model formation step S1, multiple model concretes 9 may be formed by varying the vibration time of the vibrator 4. The surface roughness and compressive strength of multiple model concretes 9 with different vibration times of the vibrator 4 may be measured, and the vibration time of the vibrator 4 may be determined in the construction method determination step S4.

As described above, the method for determining the concrete construction method of this embodiment includes a model formation step S1, a surface roughness measurement step S2, a compressive strength measurement step S3, and a construction method determination step S4. In the model formation step S1, concrete 1 is poured into a formwork 2, and compacted by a vibrator 4 inserted into a predetermined location to form a model concrete 9. In the surface roughness measurement step S2, after removing the formwork 2, the surface roughness of multiple parts of the model concrete 9 that are different distances from the insertion position of the vibrator is measured by a 3D scanner. In the compressive strength measurement step S3, the compressive strength of multiple parts that are different distances from the insertion position of the vibrator 4 is measured by a test using a part of the model concrete 9. In the construction method determination step S4, the insertion interval of the vibrator 4 when constructing the concrete 1 at the construction site is determined based on the distance from the insertion position of the vibrator 4 to the part of the model concrete 9 that meets the predetermined required levels for both surface roughness and compressive strength.

By carrying out the steps from model formation step S1 to construction method determination step S4, it is possible to determine the insertion interval of the vibrator 4 that satisfies the required levels of both surface roughness and compressive strength. By appropriately determining the insertion interval of the vibrator 4, the quality of the concrete 1 at the construction site is improved. Furthermore, the surface roughness measurement step S2 and the compressive strength measurement step S3 can be carried out the day after compaction using the vibrator 4 in the model formation step S1. Therefore, the method of determining the concrete construction method of this embodiment can quickly determine a construction method for forming high-quality concrete. As a result, it becomes possible to efficiently compact the concrete 1 at the construction site.

As described above, in the method for determining the concrete construction method of this embodiment, in the model formation step S1, when compaction is performed by the vibrator 4, sensors 5 that detect vibrations are placed on multiple parts of the surface of the concrete 1 that are at different distances from the insertion position of the vibrator 4.

There is a correlation between the vibrations detected on the surface of the concrete 1 when compacting with the vibrator 4 and the compressive strength of the model concrete 9. Therefore, it is possible to calculate the compressive strength of the model concrete 9 based on the vibrations detected by the sensor 5. When measuring the compressive strength using extracted cores, labor and time are required according to the number of cores to be extracted. In contrast, it is easy to increase the number of sensors 5. Therefore, by calculating the compressive strength using the sensor 5, it is possible to supplement the compressive strength at positions where the cores could not be extracted. Therefore, the method of determining the concrete construction method of this embodiment can further improve the accuracy of the insertion interval of the vibrator 4 determined in the construction method determination step S4. In addition, it is also possible to check the quality of not only the surface of the concrete 1 but also the inside by using the data detected by the sensor 5. The data detected by the sensor 5 can also be used to set the compaction time or the strength of the vibrator 4.

REFERENCE SIGNS LIST 1 Concrete 2 Formwork 3 Cushioning material 4 Vibrator 5 Sensor 9 Model concrete R Measurement reference surface S1 Model formation step S2 Surface roughness measurement step S3 Compressive strength measurement step S4 Construction method determination step

Claims (2)

a model forming step of pouring concrete into the formwork, compacting it with a vibrator inserted at a predetermined location , and curing and hardening the concrete for a predetermined period of time to form a model concrete;
After removing the formwork, a surface roughness measuring step of measuring the surface roughness of a plurality of portions of the model concrete at different distances from the insertion position of the vibrator by a 3D scanner;
a compressive strength measuring step of measuring compressive strengths of a plurality of portions at different distances from an insertion position of the vibrator by performing a test using a portion of the model concrete;
a construction method determination step of determining an insertion interval of the vibrator when constructing the concrete at a construction site based on a distance from an insertion position of the vibrator to a portion of the model concrete that satisfies both of the required levels of the surface roughness being equal to or less than a first threshold value and the compressive strength being equal to or greater than the in-situ strength;
A method for determining the construction method of concrete, including: 2. The method of claim 1, wherein, in the model forming step, when compacting the concrete with the vibrator, sensors for detecting vibrations are disposed at a plurality of portions of the surface of the concrete at different distances from an insertion position of the vibrator.

Images