Device and method for measuring linear expansion coefficient of concrete under real curing conditions

Abstract

The present invention discloses a device for measuring the linear expansion coefficient of concrete under real-world conditions. The device comprises: a test chamber equipped with a constant temperature controller, an insulation layer, and an anti-fogging film on the inner surface of the insulation layer; two concrete supports, a temperature sensor, four strain sensors, and a hygrometer within the test chamber; the two concrete supports each being used to place a concrete specimen, the temperature sensor being used to measure the temperature of the concrete specimen; and a strain sensor attached to each concrete specimen in the axial and longitudinal directions to measure its deformation in the transverse and longitudinal directions; and a hydraulic pressure chamber connected to the test chamber via a pipe, the pipe being equipped with a constant humidity controller. The present invention also discloses a method for measuring the linear expansion coefficient of concrete under real-world conditions, which is implemented based on the device. The present invention can measure the linear expansion coefficient of concrete under real-world conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete parameter measurement, and in particular to a device and method for measuring the linear expansion coefficient of concrete under real curing conditions. Background Art

[0002] Temperature stress during dam concrete construction and operation is the primary cause of structural cracking. Understanding the linear expansion coefficient is crucial for accurately assessing concrete stress and determining temperature control standards and measures based on temperature stress optimization to prevent structural cracking. Therefore, truly understanding the linear expansion coefficient of concrete under construction conditions is a prerequisite for understanding temperature stress during construction.

[0003] At present, the water bath method is usually used to determine the linear expansion coefficient of concrete during large-scale construction. However, during the actual dam construction process, it was found that the actual temperature stress was quite different from the calculated results, and the linear expansion coefficient obtained by inversion was quite different from the initial test value.

[0004] Therefore, a new linear expansion coefficient measuring device and method are needed in this field to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for measuring the linear expansion coefficient of concrete under real curing conditions, aiming to solve the technical problem of measuring the linear expansion coefficient of concrete under real curing conditions.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A device for measuring the linear expansion coefficient of concrete under real conditions, comprising:

[0008] A test box, wherein the test box is equipped with a constant temperature controller, the test box has a thermal insulation layer and an anti-fogging film is provided on the inner surface of the thermal insulation layer;

[0009] The test box is equipped with two concrete supports, a temperature sensor, four strain sensors and a humidity meter;

[0010] The two concrete supports are respectively used to place a concrete specimen, the temperature sensor is used to measure the temperature of the concrete specimen, and the two concrete specimens are respectively attached with a strain sensor in the axial direction and the longitudinal direction to measure their deformation in the transverse and longitudinal directions;

[0011] A water pressure box is connected to the test box through a pipeline, and a constant humidity controller is installed on the pipeline.

[0012] Preferably, the test box has an exhaust hole and a lead hole, and the leads of the temperature sensor, the strain sensor and the humidity sensor pass through the lead hole;

[0013] The constant temperature controller has an electric heating rod, and the electric heating rod is located in the test box.

[0014] A method for measuring the linear expansion coefficient of concrete under real conditions, the method comprising:

[0015] Providing a device for measuring the linear expansion coefficient of concrete under real conditions as described above;

[0016] Two concrete specimens with the same size were prepared using the same concrete material;

[0017] The temperature sensor is placed inside one of the concrete specimens, and the strain sensors are attached along the transverse and longitudinal directions of the two concrete specimens;

[0018] Place the two concrete specimens on the concrete supports respectively, and record the initial temperature T0 in the test box;

[0019] Turn on the constant humidity controller to make the humidity in the test box reach the same level as the on-site concrete construction environment and continuously record the data measured by the strain sensor. After the data stabilizes, record the lateral deformation value Δε sh(l) and longitudinal deformation value Δε sh(ρ) ;

[0020] After the humidity is constant, the electric heating rod is turned on to raise the temperature in the test box to a preset temperature threshold T1;

[0021] When the temperature value measured by the temperature sensor is equal to the temperature threshold T1, the lateral deformation value Δε at this time is recorded. (l) and longitudinal deformation value Δε (ρ) ;

[0022] Step S9: Press the formula Calculation of the linear expansion coefficient α of concrete under actual curing conditions T .

[0023] Preferably, before the step of "turning on the constant humidity controller", the method further comprises: uniformly spraying anti-water accumulation spray in the test box.

[0024] The advantages of the present invention are:

[0025] The device and method for measuring the linear expansion coefficient of concrete under real curing conditions provided by the present invention can simulate the influence of temperature and humidity in a real construction environment and measure the linear expansion coefficient of concrete under real curing conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a device for measuring the linear expansion coefficient of concrete under real conditions according to the present invention;

[0027] Figure 2 It is a flow chart of a method for measuring the linear expansion coefficient of concrete under real conditions of the present invention;

[0028] Figure 3 The present invention is a schematic diagram of the installation structure of a concrete test piece, a temperature sensor, and a strain sensor. DETAILED DESCRIPTION

[0029] The present invention provides a device and method for measuring the linear expansion coefficient of concrete under real-world conditions, designed to measure the linear expansion coefficient of concrete under real-world curing conditions. Traditional indoor tests for measuring the linear expansion coefficient typically use a waterbath method to ensure consistent temperatures between the concrete interior and surface. This method involves placing a concrete specimen in a waterbath and heating it, then calculating the linear expansion coefficient through data inversion. The linear expansion coefficient measured in a waterbath is actually the linear expansion coefficient of the concrete surface at 100% humidity. However, due to the drying shrinkage characteristics of concrete, humidity significantly affects the linear expansion coefficient. Humidity levels in on-site construction environments in different regions are stable within a certain range, resulting in significant discrepancies between the linear expansion coefficient measured using the waterbath method and the linear expansion coefficient of concrete in real-world construction environments. Therefore, the present invention provides a device and method for measuring the linear expansion coefficient of concrete under real-world conditions, comprehensively considering on-site environmental temperature and humidity factors, and capable of measuring temperature and humidity separately to determine the linear expansion coefficient of concrete under real-world conditions. The present invention is further described below in conjunction with the accompanying drawings and specific examples.

[0030] See attached Figure 1 , Figure 1 The main structure of a device for measuring the linear expansion coefficient of concrete under real conditions is shown as an example. Figure 1 As shown, the device for measuring the linear expansion coefficient of concrete under real conditions provided by this embodiment includes a test box 1 and a water pressure box 2.

[0031] The test chamber 1 is equipped with a constant temperature controller 3. The test chamber 1 has an insulation layer 4 and an anti-fogging film 5 on the inner surface of the insulation layer. Two concrete supports 6, a temperature sensor 7, four strain sensors 8, and a humidity meter 9 are provided inside the test chamber 1. The test chamber 1 has an exhaust hole 10 and a lead hole 11. The leads of the temperature sensor 7, strain sensor 8, and humidity meter 9 are passed through the lead hole 10. After these leads are led out, they can be connected to the control device to facilitate data reading. The constant temperature controller 3 has an electric heating rod 12, which is located inside the test chamber 1.

[0032] Two concrete supports 6 are each used to place a concrete specimen 13. A temperature sensor 7 is used to measure the temperature of the concrete specimen. Four strain sensors 8 are attached to the concrete specimen 13 to measure its lateral and longitudinal deformation. The hydraulic tank 2 is connected to the test chamber via a pipe, and a constant humidity controller 14 is installed on the pipe.

[0033] See attached Figure 2 Based on the concrete linear expansion coefficient measuring device under real conditions, this embodiment also provides a concrete linear expansion coefficient measuring method under real conditions, such as Figure 2 As shown, the method for measuring the linear expansion coefficient of concrete under real conditions provided in this embodiment includes:

[0034] Step S1: providing a device for measuring the linear expansion coefficient of concrete under real conditions. Specifically, providing the device for measuring the linear expansion coefficient of concrete under real conditions as described above.

[0035] Step S2: Using the same concrete material, prepare two concrete specimens 13 of the same size. Specifically, the concrete in the same mixing barrel can be used to prepare two identical concrete specimens 13. In this embodiment, the concrete specimen 13 is cylindrical with a diameter of 20 cm and a height of 50 cm.

[0036] Step S3: Place the temperature sensor 7 inside one of the concrete specimens 13, and attach the strain sensor 8 along the transverse and longitudinal directions of the two concrete specimens 13. Figure 3 As shown, a temperature sensor 7 is placed at the center of one of the concrete specimens 13 to measure the temperature inside the concrete specimen 13. Strain sensors 8 are attached to the outer surfaces of the two concrete specimens 13 in the transverse and longitudinal directions to measure the deformation of the two concrete specimens 13 in the transverse and longitudinal directions. More specifically, each concrete specimen 13 is equipped with two strain sensors 8, which respectively measure the deformation in the transverse and longitudinal directions of the concrete specimen 13.

[0037] Step S4: Place two concrete specimens 13 on concrete supports 6, respectively, and record the initial temperature T0 in the test chamber 1. Specifically, each concrete specimen 13 corresponds to one concrete support 6. The two concrete specimens 13 are placed simultaneously in the test chamber 1, and various instruments and equipment are adjusted to determine the initial values ​​of various parameters.

[0038] Step S5: uniformly spraying the anti-water accumulation spray in the test box 1. Specifically, by uniformly spraying the anti-water accumulation spray in the test box 1, the humidity value in the test box 1 can be accurately regulated and stabilized by the water volume of the water pressure box 2.

[0039] Step S6: Turn on the constant humidity controller 14 to make the humidity in the test box 1 reach the same level as the on-site concrete construction environment and continue to record the data measured by the strain sensor 8. After the data stabilizes, record the lateral deformation value Δε sh(l) and longitudinal deformation value Δε sh(ρ) Specifically, since two concrete specimens are set in this embodiment, the recorded lateral deformation value Δε sh(l) and longitudinal deformation value Δε sh(ρ) , which corresponds to the average of the lateral and longitudinal deformation values ​​of the two concrete specimens 13. Turn on the constant humidity controller 8 to make the humidity in the test chamber 1 the same as the on-site concrete construction environment. The humidity value of the on-site concrete construction environment is obtained through on-site measurement and is 60% in this embodiment. After 2 to 3 hours, record the value of the strain sensor 8. After it stabilizes, record the strain value and lateral deformation Δε at this time. sh(l) and longitudinal deformation Δε sh(ρ) .

[0040] Step S7: After the humidity is constant, the electric heating rod 12 is turned on to raise the temperature in the test box 1 to a preset temperature threshold T1. Specifically, the electric heating rod 12 is turned on to raise the temperature in the test box 1. The temperature threshold T1 can be the temperature of the on-site concrete construction environment, which is 40°C in this embodiment.

[0041] Step S8: When the temperature value measured by the temperature sensor 7 is equal to the temperature threshold T1, record the lateral deformation value Δε at this time (l) and longitudinal deformation value Δε (ρ) Specifically, the temperature in the test box 1 is kept constant for about 2 hours. When the temperature inside the concrete specimen 13 reaches the temperature threshold, the lateral deformation value Δε at this time is recorded. (l) and longitudinal deformation value Δε (ρ) Similarly, the lateral deformation value Δε sh(l) and longitudinal deformation value Δε sh(ρ) , which also corresponds to the mean of the lateral deformation values ​​and the mean of the longitudinal deformation values ​​of the two concrete specimens 13.

[0042] Step S9: Calculate the linear expansion coefficient α of concrete under actual curing conditions according to formula (1): T .

[0043] Specifically, formula (1) is as follows:

[0044]

[0045] Since concrete has a Poisson effect, the Poisson ratio of concrete is usually 0.167. Therefore, the influence of the longitudinal deformation of concrete needs to be considered during calculation. The above data is substituted into the formula to calculate the linear expansion coefficient α of concrete under actual curing conditions.T .

[0046] The above are preferred embodiments of the present invention and the technical principles used therein. For those skilled in the art, any obvious changes such as equivalent transformations, simple replacements, etc. based on the technical solution of the present invention, without departing from the spirit and scope of the present invention, are within the scope of protection of the present invention.

Claims

1. A method for measuring the linear expansion coefficient of concrete under real conditions, characterized in that: The method comprises: A device for measuring the linear expansion coefficient of concrete under real conditions is provided, the device comprising: A test box, wherein the test box is equipped with a constant temperature controller, the test box has a thermal insulation layer and an anti-fogging film is provided on the inner surface of the thermal insulation layer; The test box is equipped with two concrete supports, a temperature sensor, four strain sensors and a humidity meter; The two concrete supports are respectively used to place a concrete specimen, the temperature sensor is used to measure the temperature of the concrete specimen, and the two concrete specimens are respectively attached with a strain sensor in the axial direction and the longitudinal direction to measure the strain in the transverse and longitudinal directions; A hydraulic box connected to the test box via a pipe, and a constant humidity controller is installed on the pipe; The test box has an exhaust hole and a lead hole, and the leads of the temperature sensor, the strain sensor and the humidity sensor pass through the lead hole; The constant temperature controller has an electric heating rod, and the electric heating rod is located in the test box; Two concrete specimens with the same size were prepared using the same concrete material; The temperature sensor is placed inside one of the concrete specimens, and the strain sensors are attached along the transverse and longitudinal directions of the two concrete specimens; Place the two concrete specimens on the concrete supports respectively, and record the initial temperature T0 in the test box; Turn on the constant humidity controller to make the humidity in the test box reach the same level as the on-site concrete construction environment and continuously record the data measured by the strain sensor. After the data stabilizes, record the lateral deformation value Δε sh(l) and longitudinal deformation value △ε sh(ρ) ; After the humidity is constant, the electric heating rod is turned on to raise the temperature in the test box to a preset temperature threshold T1; When the temperature value measured by the temperature sensor is equal to the temperature threshold T1, the lateral deformation value Δε at this time is recorded. (l) and longitudinal deformation value △ε (ρ) ; According to the formula Calculation of the linear expansion coefficient α of concrete under actual curing conditions T .

2. The method for measuring the linear expansion coefficient of concrete under real conditions as claimed in claim 1, characterized in that: Before the step of "starting the constant humidity controller", the method further includes: Evenly spray the anti-water accumulation spray inside the test box.

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