JP2023057604A - Concrete testing method and concrete testing system - Google Patents

Abstract

To provide a concrete testing method and a concrete testing system for checking the quality of concrete.SOLUTION: A concrete testing method includes a temperature analysis process (step S101) that performs temperature analysis during concrete curing based on the design information of the concrete structure, a temperature history acquisition process (step S102) that acquires the temperature history of an evaluation area in the concrete structure, a specimen curing process (step S103) that cures a specimen based on the design information under a test environment that can reproduce the temperature history, and a test process (step S104) that performs quality test of the specimen by reproducing the temperature history.SELECTED DRAWING: Figure 1

Description

The present invention relates to a concrete testing method and a concrete testing system for confirming the quality of concrete.

In recent years, due to the increase in height and size of buildings, it is necessary to increase the strength and increase the size of cast-in-place concrete piles that serve as foundations. Increasing the strength and increasing the size of the pile causes a significant increase in temperature inside the member due to the reaction heat associated with the hydration reaction between cement and water after concrete is poured. A high temperature inside a concrete structure increases the strength at the initial age, but tends to cause stagnation or deterioration of the strength in the long term. Therefore, the strength of concrete that has undergone a history of high temperatures may be lower than the strength of concrete that has not undergone a history of high temperatures. For this reason, it is necessary to grasp in advance the strength of a concrete structure whose internal temperature is expected to rise. For example, Patent Literature 1 discloses a method of checking the concrete strength of a concrete structure using actual structural members and simulated members smaller than the actual structural members.

Specifically, a heating device and a temperature sensor are installed on the outer periphery of each of the real component and the simulated member, and the outer periphery is surrounded by a heat insulating material. Then, the temperature history during heating is obtained for the actual constituent member, and the simulated member is heated so that the temperature history based on the detection value of the temperature sensor matches the temperature history of the actual constituent member. As a result, the concrete strength of the simulated member becomes equal to that of the actual structural member, so the concrete strength of the actual structural member is confirmed with the simulated member.

JP 2014-153071 A

However, in the method described in Patent Document 1, in addition to the actual constituent members, a heating device for heating the actual constituent members, a heat insulating material surrounding the actual constituent members, and the like are required. becomes.

A concrete test method for solving the above problems includes a temperature analysis step of performing temperature analysis during concrete curing based on design information of the concrete structure, and based on the result of the temperature analysis, determining the temperature A temperature history acquisition step of acquiring a history, a specimen curing step of curing the specimen based on the design information in a test environment that can reproduce the temperature history, and reproducing the temperature history to reproduce the specimen and a test step of performing a quality test.

ADVANTAGE OF THE INVENTION According to this invention, the quality test about a concrete structure can be performed with a small-scale test apparatus.

The figure which shows an example of a concrete structure. 4 is a flowchart showing the procedure of a concrete testing method according to the first embodiment; 5 is a graph showing an example of temperature history in the first embodiment; In the first embodiment, (a) a diagram schematically showing a state in which the formwork is supported on the base, (b) a diagram schematically showing a state in which the formwork is covered with a heating element, (c) a heating element The figure which shows typically the state covered with the covering. The figure which shows typically schematic structure of the concrete test method in 2nd Embodiment. (a) Graph showing an example of moisture loss, (b) Graph showing an example of compressive strength in the second embodiment.

(First embodiment)
A first embodiment of a concrete testing method and a concrete testing system will be described with reference to FIGS. 1 to 4. FIG.

The concrete test method is a method of testing that is performed for the purpose of confirming the quality of evaluation areas in concrete structures. The evaluation area is, for example, a portion whose temperature is higher than that of the surrounding portion during concrete curing.

As shown in FIG. 1, one example of a concrete structure is a cast-in-place concrete pile 11 (hereinafter simply referred to as pile 11) that is placed underground to support a middle-rise or high-rise building. The pile 11 has a shaft portion 12 and an enlarged diameter portion 13 having a larger diameter than the shaft portion 12 . A portion having the largest diameter in the enlarged diameter portion 13 is a maximum diameter portion 14 .

As shown in FIG. 2, the concrete testing method includes a temperature analysis step (step S101), a temperature history acquisition step (step S102), a specimen curing step (step S103), and a test step (step S104).

In the temperature analysis step (step S101), temperature analysis is performed during concrete curing of the concrete structure. Specifically, using an analysis device mainly composed of an information processing device, a simulation based on the design information of the concrete structure is performed, and the temperature change inside the concrete structure during curing of the concrete is analyzed. The design information is information including the shape and size of the concrete structure, the composition of the concrete, the cement ratio, the curing method, the installation environment, and the like.

The information processing apparatus acquires various kinds of information and executes various kinds of processing based on the acquired various kinds of information, programs and various data stored in the memory. The information processing device can be configured as a circuit including one or more dedicated hardware circuits such as ASIC, one or more processors that operate according to a computer program (software), or a combination thereof. A processor includes a CPU and memory, such as RAM and ROM, which stores program code or instructions configured to cause the CPU to perform processes. Memory or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer.

The temperature analysis may be performed with the entire concrete structure as the analysis target if the evaluation area in the concrete structure is not specified. This makes it possible to identify the evaluation area. Further, when the evaluation area is empirically specified, the time required for the temperature analysis can be shortened by performing the temperature analysis with the surrounding area including the evaluation area as the analysis target. For example, when the concrete structure is the pile 11 described above, the temperature is highest at the center of the maximum diameter portion 14, so temperature analysis is performed using the center of the maximum diameter portion 14 as an evaluation region. A temperature analysis is performed using a finite element method or the like that divides an analysis target into a plurality of meshes.

In the temperature history acquisition step (step S102), the temperature history of the evaluation region is acquired based on the result of the temperature analysis. Specifically, based on the temperature history of each mesh obtained by temperature analysis, the temperature history of the evaluation region is obtained. For example, the temperature history of the mesh with the highest temperature is acquired as the temperature history of the evaluation region.

FIG. 3 is a graph showing an example of temperature history in the evaluation area. FIG. 3 is a graph showing the temperature history in the evaluation region for each size of the maximum diameter portion 14, with the central portion of the maximum diameter portion 14 of the pile 11 as the evaluation region. As shown in the figure, in the pile 11, the larger the maximum diameter portion 14, the higher the maximum temperature during curing. Also, when the pile diameter of the maximum diameter portion 14 increases, the maximum temperature may exceed the boiling point of water.

In the test piece curing step (step S103), a test piece to be tested is manufactured and cured by a curing device.
As shown in FIG. 4( a ), the curing device 20 has, for example, a base 21 and a formwork 22 . The specimen 15 is manufactured by pouring concrete based on the design information into the formwork 22 supported by the base 21 . The specimen 15 is manufactured with a smaller volume than the concrete structure. If the pile 11 with a pile diameter of 5 m at the maximum diameter portion 14 is a concrete structure, and the center portion of the maximum diameter portion 14 is to be evaluated, the test piece 15 is, for example, a cylindrical or prismatic shape having a cross section of about 1 m. Manufactured to shape.

As shown in FIGS. 4(b) and 4(c), the curing device 20 comprises a heater 23, a heat insulating material 24, a temperature sensor 25, and a controller 26. As shown in FIG.
The heating body 23 heats the specimen 15 . An example of the heating element 23 is a planar heating element wound around the mold 22 from the outside.

The heat insulating material 24 is a covering that covers the specimen 15 . The heat insulating material 24 covers the heating element 23 wound around the mold 22 from the outside. The heat insulating material 24 may cover the specimen 15 from above.
The temperature sensor 25 detects the temperature inside the specimen 15 and outputs the detected temperature to the controller 26 .

The control unit 26 is mainly composed of an information processing device. The control unit 26 controls heating of the specimen 15 by the heater 23 based on the detected value of the temperature sensor 25 .
In the test step (step S104), the temperature of the test piece 15 is adjusted so that the temperature history acquired in the temperature history acquisition step (step S102) is reproduced in the test piece 15, and then a part of the test piece 15 is tested. Various quality tests are carried out as pieces.

Specifically, the temperature history acquired in the temperature history acquisition step (step S102) is input to the control unit 26. FIG. Then, the controller 26 controls the heating by the heating element 23 so that the detected value of the temperature sensor 25 becomes the temperature history. After that, a part of the test piece is taken out by boring or the like, and various quality tests such as a compressive strength test are performed using it as a test piece.

Actions and effects of the first embodiment will be described.
(1-1) The temperature of the specimen 15 is controlled by the curing device 20 so that the temperature history of the evaluation region obtained by the temperature analysis is reproduced. Therefore, even when checking the quality of a large member such as the pile 11, the quality can be checked with a small-scale apparatus configuration.

(1-2) Temperature analysis is performed based on the design information of the concrete structure. As a result, according to the composition of the concrete that forms the concrete structure, it is possible to obtain a temperature history that is closer to the actual temperature history, taking into consideration the heat transfer of the reaction heat to the aggregates and the heat capacity of the aggregates. can.

(1-3) By acquiring the temperature history at the center of the maximum diameter portion 14 of the pile 11 and reproducing the acquired temperature history with the specimen 15, the center of the maximum diameter portion 14 is the evaluation area Quality Confirmation can be done.

(1-4) Since the specimen 15 is heated by the heating element 23, the degree of freedom regarding the temperature of the specimen 15 is increased. As a result, the specimen 15 can be heated to a temperature exceeding 100° C., for example, so that the degree of freedom regarding the test object can be increased.

(Second embodiment)
A second embodiment of the concrete testing method and concrete testing system will be described with reference to FIGS. 5 and 6. FIG. The concrete testing method and concrete testing system of the second embodiment have the same main configurations as those of the first embodiment. Therefore, in the second embodiment, portions different from the first embodiment will be described in detail, and the same reference numerals will be given to the same portions as in the first embodiment, and detailed description thereof will be omitted.

The pile 11, which is a concrete structure, is arranged in the ground. Therefore, the moisture condition inside the pile 11 after concrete is placed depends on the surrounding environment of the pile 11, more specifically, the ambient temperature, humidity, and moisture supply condition. Therefore, in the second embodiment, the surrounding environment in the ground is acquired from the result of the soil survey conducted in advance, and the evaluation area of the pile 11 is evaluated based on the acquired surrounding environment and the design information of the pile 11. Predict moisture conditions. In the concrete test method of the second embodiment, the concrete is cured in a test environment that can simulate the moisture state predicted for such an evaluation area.

As shown in FIG. 5, in the test piece curing step (step S103), after manufacturing the test piece 30, the test piece 30 is cured in a test environment simulating the moisture state predicted for the evaluation area. Specifically, after manufacturing a small test piece having a diameter of 100 mm and a height of about 200 mm as the test piece 30, the test piece 30 is cured in a test environment simulating the moisture state predicted for the evaluation area.

For example, in case 1, which allows the evaporation and dissipation of moisture contained in concrete, the specimen 30 is covered with a metal container 31 having an open top opening, and is covered with a heating furnace 32 which is a heating body. stored in.

In case 2, which allows some evaporation and dissipation of water contained in concrete, the specimen 30 is a container composed of a metal container body 33 having an upper opening and a film 34 covering the upper opening. 35 is stored in a heating furnace 32 as a covering. Such a test environment simulates the moisture situation inside a concrete structure where the moisture concentration is not too high.

In the case 3 where it is desired to prevent evaporation and dissipation of water contained in the concrete as much as possible, the specimen 30 is composed of a metal container body 36 having an upper opening and a lid 37 sealing the upper opening. The container 38 is stored in the heating furnace 32 as a covering. Such a test environment simulates the moisture conditions inside the concrete structure where the moisture concentration is near saturation. The container main body 36 and the lid 37 are connected by screwing, for example, with one or more annular sealing members provided between the container main body 36 and the lid 37 .

Then, in the test step (step S104), the heating by the heating furnace 32 is controlled by the control unit 26 so that the temperature history acquired in the temperature history acquisition step (step S102) is reproduced in the test piece 30. Various quality tests are performed using the product itself as a test piece.

FIG. 6(a) is a graph showing the amount of moisture loss per unit volume of the specimen 30 at the ages of 4 days and 91 days. FIG. 6(b) is a graph showing the compressive strength at 4 days of age, 28 days of age, and 91 days of age. In addition, in FIG.6(b), the two-dot chain line has shown the reference strength in material age 28 days.

As shown in FIG. 6( a ), it was confirmed that the amount of moisture loss was large in the order of Case 1, Case 2, and Case 3 in each of the ages of 4 days and 91 days. Further, as shown in FIG. 6(b), the larger the amount of moisture loss, the higher the order of case 1, case 2, and case 3 in each of 4 days of age, 28 days of age, and 91 days of age. A decrease in compressive strength was observed.

According to the second embodiment, in addition to the actions and effects described in (1-1) to (1-4) described in the first embodiment, the following actions and effects are obtained.
(2-1) A test can be conducted under a test environment that simulates the moisture condition of the evaluation area. Thereby, the reliability of the test result of the evaluation area can be improved.

(2-2) By using the containers 35 and 38 as the covering, even when the test piece 30 is heated to a temperature exceeding 100°C, the test can be performed under a test environment in which the dissipation of moisture is suppressed. It can be carried out.

The first and second embodiments can be modified and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

- The evaluation area of the concrete structure is not limited to the central portion of the maximum diameter portion 14 as long as it is an area that becomes hot during curing of the concrete.
- The concrete structure is not limited to the pile 11 . For example, concrete structures may be pillars, beams, walls, floors, etc. installed on the ground. Even in such a case, quality confirmation can be performed with a small-scale apparatus configuration, and a test according to the internal moisture condition can be performed.

DESCRIPTION OF SYMBOLS 11... Cast-in-place concrete pile, 12... Shaft part, 13... Expanded diameter part, 14... Maximum diameter part, 15... Specimen, 20... Curing device, 21... Base, 22... Formwork, 23... Heating body, 24... Heat insulating material 25 Temperature sensor 26 Control unit 30 Specimen 31 Container 32 Heating furnace 33 Container body 34 Film 35 Container 36 Container body 37 Lid body 38... Container.

Claims (6)

a temperature analysis step of performing temperature analysis during concrete curing based on the design information of the concrete structure;
a temperature history acquisition step of acquiring a temperature history of an evaluation area in the concrete structure based on the result of the temperature analysis;
a test piece curing step of curing the test piece based on the design information in a test environment capable of reproducing the temperature history;
and a testing step of reproducing the temperature history and performing a quality test of the specimen. The concrete testing method according to claim 1, wherein the design information includes a composition of concrete in the concrete structure. The concrete testing method according to claim 1 or 2, wherein in the temperature analysis step, the temperature analysis is performed based on pile design information. The pile has a shaft portion and an enlarged diameter portion having a diameter larger than that of the shaft portion,
The concrete testing method according to claim 3, wherein in the temperature history acquisition step, the temperature history is acquired with the central portion of the enlarged diameter portion as the evaluation region. The concrete testing method according to any one of claims 1 to 4, wherein, in the test piece curing step, the test piece is cured while being covered with a covering so as to simulate the moisture condition of the evaluation area. A concrete test system using an analysis device and a curing device,
The analysis device is
Performing a temperature analysis during concrete curing based on design information of a concrete structure, obtaining a temperature history of an evaluation target in the concrete structure,
The curing device is
a heating element for heating the specimen;
a covering covering the specimen;
a temperature sensor that detects the temperature inside the specimen;
a control unit that controls the heating element based on the detected value of the temperature sensor,
The concrete testing system, wherein the control section controls the heating body such that the temperature history of the evaluation object is reproduced in the specimen.

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