Concrete Testing Methods

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

[Technical Field]

[0001] The present invention relates to a concrete testing method for confirming the quality of concrete. By law Regarding. [Background technology]

[0002] In recent years, the increasing height and size of buildings has necessitated the strengthening and enlargement of cast-in-place concrete piles, which serve as foundations. Increasing the strength and size of piles leads to significant increases in temperature inside the components due to the heat of reaction associated with the hydration reaction between cement and water after the concrete is poured. While increases in temperature inside components of concrete structures increase the strength at the initial age, they tend to result in stagnation or slowdown in long-term strength. Therefore, the strength of concrete that has been subjected to high-temperature history may be lower than the strength of concrete under normal conditions that have not been subjected to high-temperature history. For this reason, it is necessary to determine in advance the strength of concrete structures that are expected to experience high temperatures inside the components. For example, Patent Document 1 discloses a method for confirming the concrete strength of a concrete structure using actual components and simulated components that are smaller than the actual components.

[0003] Specifically, a heating device and a temperature sensor are installed on the outer periphery of each of the actual and simulated components, and the outer periphery is surrounded by insulating material. The temperature history of the actual components during heating is then acquired, and the simulated components are heated so that the temperature history based on the temperature sensor detection values ​​matches the temperature history of the actual components. This ensures that the concrete strength of the simulated components is equivalent to that of the actual components, so the concrete strength of the actual components can be confirmed using the simulated components. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-153071 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method described in Patent Document 1 requires not only the actual component, but also a heating device for heating the actual component, a heat insulating material for surrounding the actual component, and the like, which results in a large-scale testing device. [Means for solving the problem]

[0006] A concrete testing method that solves the above-mentioned problems includes a temperature analysis step of performing temperature analysis during concrete curing based on design information of a concrete structure, a temperature history acquisition step of acquiring the temperature history of an evaluation area in the concrete structure based on the results of the temperature analysis, a specimen curing step of curing a specimen based on the design information in a test environment that can reproduce the temperature history, and a testing step of reproducing the temperature history and performing a quality test on the specimen. [Effects of the Invention]

[0007] According to the present invention, quality tests on concrete structures can be carried out using small-scale testing equipment. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of a concrete structure. [Figure 2] 1 is a flowchart showing the steps of a concrete testing method according to the first embodiment. [Figure 3] 4 is a graph showing an example of a temperature history in the first embodiment. [Figure 4] In the first embodiment, (a) is a diagram showing a state in which a formwork is supported on a base, (b) is a diagram showing a state in which the formwork is covered with a heating body, and (c) is a diagram showing a state in which the heating body is covered with a covering body. [Figure 5] FIG. 10 is a diagram schematically illustrating the general configuration of a concrete testing method according to a second embodiment. [Figure 6]10A is a graph showing an example of a water loss amount, and FIG. 10B is a graph showing an example of a compressive strength in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) A first embodiment of a concrete testing method and a concrete testing system will be described with reference to FIGS.

[0010] The concrete testing method is a test method performed to confirm the quality of an evaluation area in a concrete structure. The evaluation area is, for example, a part that will be hotter than the surrounding areas during concrete curing.

[0011] As shown in Figure 1, an 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 mid-rise or high-rise building. This pile 11 has a shaft portion 12 and an expanded diameter portion 13 that has a larger diameter than the shaft portion 12. The part of the expanded diameter portion 13 that has the largest diameter is a maximum diameter portion 14.

[0012] As shown in FIG. 2, the concrete testing method includes a temperature analysis step (step S101), a temperature history acquisition step (step S102), a test specimen curing step (step S103), and a testing step (step S104).

[0013] In the temperature analysis step (step S101), a temperature analysis is performed on the concrete structure during concrete curing. Specifically, an analysis device configured mainly with an information processing device is used to perform a simulation based on the design information of the concrete structure, and the temperature transition inside the concrete structure during concrete curing is analyzed. The design information includes the shape and size of the concrete structure, the concrete composition, cement ratio, curing method, installation environment, etc.

[0014] An information processing device acquires various types of information and performs various processes based on the acquired information, as well as programs and various data stored in memory. The information processing device may be configured as a circuit including one or more dedicated hardware circuits such as an ASIC, one or more processors operating according to a computer program (software), or a combination thereof. The processor includes a CPU and memory such as RAM and ROM, which stores program code or instructions configured to cause the CPU to perform processing. Memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0015] If an evaluation area in a concrete structure has not been specified, the temperature analysis may be performed on the entire concrete structure as the analysis target. This allows the evaluation area to be specified. If the evaluation area has been empirically specified, the time required for the temperature analysis can be shortened by performing the temperature analysis on the surrounding area including the evaluation area as the analysis target. For example, if the concrete structure is the above-mentioned pile 11, the temperature is highest at the center of the maximum diameter part 14, so the temperature analysis is performed on the center of the maximum diameter part 14 as the evaluation area. The temperature analysis is performed using a finite element method or the like that divides the analysis target into multiple meshes.

[0016] In the temperature history acquisition step (step S102), the temperature history of the evaluation area is acquired based on the results of the temperature analysis. Specifically, the temperature history of the evaluation area is acquired based on the temperature history of each mesh obtained by the temperature analysis. For example, the temperature history of the mesh with the highest temperature is acquired as the temperature history of the evaluation area.

[0017] Fig. 3 is a graph showing an example of the temperature history in the evaluation area. Fig. 3 is a graph showing the temperature history in the evaluation area for each size of the maximum diameter part 14 of the pile 11, with the center of the maximum diameter part 14 being the evaluation area. As shown in the figure, the larger the maximum diameter part 14 of the pile 11, the higher the maximum temperature during curing. Furthermore, when the pile diameter of the maximum diameter part 14 becomes larger, the maximum temperature may exceed the boiling point of water.

[0018] In the test specimen curing step (step S103), a test specimen to be tested is manufactured and cured in a curing device. As shown in FIG. 4(a), the curing apparatus 20 has, for example, a base 21 and a formwork 22. The test specimen 15 is produced by pouring concrete based on design information into the formwork 22 supported by the base 21. The test specimen 15 is produced with a smaller volume than the concrete structure. If the concrete structure is a pile 11 with a pile diameter of 5 m at its maximum diameter part 14, and the center of the maximum diameter part 14 is the object of evaluation, the test specimen 15 is produced in the shape of a cylinder or prism with a cross section of, for example, about 1 m.

[0019] As shown in FIGS. 4(b) and 4(c), the curing device 20 is composed of a heater 23, a heat insulating material 24, a temperature sensor 25, and a control unit . The heater 23 heats the specimen 15. An example of the heater 23 is a sheet heating element that is wound around the mold 22 from the outside.

[0020] The heat insulating material 24 is a covering that covers the specimen 15. The heat insulating material 24 covers from the outside the heater 23 that is wound around the formwork 22. The heat insulating material 24 may also cover the specimen 15 from above. The temperature sensor 25 detects the temperature inside the specimen 15 and outputs the detected temperature to the control unit 26 .

[0021] The control unit 26 is mainly configured with an information processing device. The control unit 26 controls the heating of the specimen 15 by the heater 23 based on the detected value of the temperature sensor 25. In the testing process (step S104), the temperature of the specimen 15 is adjusted so that the temperature history acquired in the temperature history acquisition process (step S102) is reproduced in the specimen 15, and then various quality tests are performed using a portion of the specimen 15 as a test piece.

[0022] Specifically, the temperature history acquired in the temperature history acquisition step (step S102) is input to the control unit 26. Then, the control unit 26 controls heating by the heater 23 so that the detected value of the temperature sensor 25 becomes the temperature history. Thereafter, a part of the test piece is extracted by boring or the like, and various quality tests, for example, a compressive strength test, are performed on it as a test piece.

[0023] The operation 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 area obtained by the temperature analysis is reproduced. Therefore, even when checking the quality of a large component such as a pile 11, the quality check can be performed using a small-scale device configuration.

[0024] (1-2) Temperature analysis is performed based on the design information of the concrete structure. This allows for a temperature history that takes into account the heat conduction of reaction heat to the aggregate and the heat capacity of the aggregate, depending on the composition of the concrete that makes up the concrete structure, i.e., a temperature history that is closer to the actual temperature history.

[0025] (1-3) By acquiring the temperature history at the center of the maximum diameter part 14 of the pile 11 and reproducing the acquired temperature history in the test specimen 15, quality confirmation can be performed with the center of the maximum diameter part 14 as the evaluation area.

[0026] (1-4) Since the heating of the specimen 15 is performed by the heater 23, the degree of freedom in terms of the temperature of the specimen 15 is increased. This allows the specimen 15 to be heated to a temperature exceeding 100°C, for example, thereby increasing the degree of freedom in terms of the test object.

[0027] (Second embodiment) A second embodiment of a concrete testing method and a concrete testing system will be described with reference to Figures 5 and 6. The concrete testing method and concrete testing system of the second embodiment have the same main configuration as the first embodiment. Therefore, in the second embodiment, only the parts that differ from the first embodiment will be described in detail, and parts that are the same as those in the first embodiment will be denoted by the same reference numerals and will not be described in detail again.

[0028] A pile 11, which is a concrete structure, is placed underground. Therefore, the moisture condition inside the pile 11 after concrete is poured depends on the surrounding environment of the pile 11, more specifically, the surrounding temperature, humidity, and moisture supply condition. Therefore, in the second embodiment, the surrounding environment in the ground is acquired from the results of a soil survey conducted in advance, and the moisture condition in the evaluation area of ​​the pile 11 is predicted based on the acquired surrounding environment and design information of the pile 11. In the concrete testing method of the second embodiment, concrete is cured in a test environment that can simulate the predicted moisture condition in the evaluation area.

[0029] 5, in the specimen curing step (step S103), the specimen 30 is manufactured, and then the specimen 30 is cured in a test environment that simulates the moisture conditions predicted for the evaluation area. Specifically, a small test piece with a diameter of about 100 mm and a height of 200 mm is manufactured as the specimen 30, and then the specimen 30 is cured in a test environment that simulates the moisture conditions predicted for the evaluation area.

[0030] For example, in case 1, in which evaporation and dissipation of water contained in concrete is allowed, the test specimen 30 is covered by a metal container 31 with an open top and stored in a heating furnace 32, which is a heating body.

[0031] In Case 2, which allows for a certain degree of evaporation and dissipation of the moisture contained in the concrete, the test specimen 30 is placed in the heating furnace 32, covered with a container 35 consisting of a metal container body 33 with an opening at the top and a film 34 covering the opening. This test environment simulates the moisture conditions inside a concrete structure where the moisture concentration is not very high.

[0032] In Case 3, where evaporation and dissipation of water contained in the concrete must be prevented as much as possible, the specimen 30 is placed in the heating furnace 32, covered by a container 38 consisting of a metal container body 36 with an opening at the top and a lid 37 that seals the opening. This test environment simulates the moisture conditions inside a concrete structure where the moisture concentration is close to saturation. The container body 36 and the lid 37 are connected by a screw connection, for example, with one or more annular sealants disposed between the container body 36 and the lid 37.

[0033] Then, in the testing process (step S104), the control unit 26 controls the heating by the heating furnace 32 so that the temperature history acquired in the temperature history acquisition process (step S102) is reproduced in the test piece 30, and various quality tests are then performed on the test piece 30 itself.

[0034] Fig. 6(a) is a graph showing the moisture loss per unit volume of specimen 30 at ages of 4 days and 91 days. Fig. 6(b) is a graph showing the compressive strength at ages of 4 days, 28 days, and 91 days. In Fig. 6(b), the dashed double-dashed line indicates the reference strength at age 28 days.

[0035] As shown in Figure 6(a), at the ages of 4 days and 91 days, the amount of moisture loss was greatest in Case 1, followed by Case 2 and Case 3. Also, as shown in Figure 6(b), the compressive strength decreased as the amount of moisture loss increased in the order of Case 1, followed by Case 2 and Case 3 at the ages of 4 days, 28 days and 91 days.

[0036] According to the second embodiment, in addition to the effects (1-1) to (1-4) described in the first embodiment, the following effects and advantages can be obtained. (2-1) Tests can be performed in a test environment that simulates the moisture conditions in the evaluation area, thereby increasing the reliability of the test results in the evaluation area.

[0037] (2-2) By using the containers 35 and 38 as the covering body, even when the specimen 30 is heated to a temperature exceeding 100°C, the test can be performed in a test environment in which the escape of moisture is suppressed.

[0038] The first and second embodiments can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0039] The evaluation area of ​​the concrete structure is not limited to the center of the maximum diameter portion 14, as long as it is an area that becomes hot during concrete curing. The concrete structure is not limited to the pile 11. For example, the concrete structure may be a pillar, beam, wall, floor, or the like installed on the ground. Even in such cases, quality checks can be performed using a small-scale device configuration, and tests can be performed according to the internal moisture conditions. [Explanation of symbols]

[0040] 11...cast-in-place concrete pile, 12...shaft, 13...expansion section, 14...maximum diameter section, 15...test specimen, 20...curing device, 21...base, 22...formwork, 23...heating element, 24...insulating material, 25...temperature sensor, 26...control section, 30...test specimen, 31...container, 32...heating furnace, 33...container body, 34...film, 35...container, 36...container body, 37...lid, 38...container.

Claims

1. a temperature analysis step of performing temperature analysis during concrete curing based on 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 specimen curing step of curing a test specimen based on the design information in a test environment capable of reproducing the temperature history; a testing step of reproducing the temperature history and performing a quality test on the specimen, In the test specimen curing step, a test specimen smaller than the concrete structure and having a cross-sectional width of about 1 m is manufactured, a heater is wrapped around the formwork of the test specimen, and the test specimen is cured in a state where the heater is covered with a covering from the outside so that the moisture condition in the evaluation area can be simulated. Concrete testing methods.

2. a temperature analysis step of performing temperature analysis during concrete curing based on 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 specimen curing step of curing a test specimen based on the design information in a test environment capable of reproducing the temperature history; a testing step of reproducing the temperature history and performing a quality test on the specimen, In the test specimen curing step, the test specimen is cured in a state where it is covered with a covering body so as to simulate the moisture condition in the evaluation area, The coating body is a metal container body having an upper opening; a lid that seals the upper opening; an annular sealing material disposed between the container body and the lid body; Concrete testing methods.

3. In the temperature analysis step, a temperature analysis is performed on the evaluation area and a surrounding area of ​​the evaluation area as analysis targets.

3. The method for testing concrete according to claim 1 or 2.

4. The design information includes a composition of concrete in the concrete structure. The concrete testing method according to any one of claims 1 to 3.

5. In the temperature analysis step, the temperature analysis is performed based on the design information of the pile. The concrete testing method according to any one of claims 1 to 4.

6. The pile has a shaft portion and an expanded diameter portion having a diameter larger than that of the shaft portion, In the temperature history acquisition step, the temperature history is acquired using the center of the expanded diameter portion as the evaluation region. The method for testing concrete according to claim 5.

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