A device and method for measuring adiabatic temperature rise of concrete

Abstract

The present invention discloses a concrete adiabatic temperature rise measurement device and method, belonging to the technical field of experimental devices. The sample tube and the insulation box are both spherical, the sample tube is nested inside the insulation box, and there is a vacuum between the sample tube and the insulation box; an insulation layer is provided outside the insulation box; one end of a plurality of temperature measuring inserts is connected to the sample tube, and the other end is distributed on a spherical surface concentric with the sample tube inside the sample tube; an internal temperature measuring device is provided inside the temperature measuring insert, and an external temperature measuring device and a heating device are provided on the outer wall of the sample tube, and the internal temperature measuring device, the external temperature measuring device and the heating device are respectively connected to a data acquisition and control system. The device has a good insulation effect, and the measured temperature is closer to the actual value. It can perform high-precision measurements in long-term experiments, providing an important basis for theoretical analysis and engineering practice.

Description

Technical Field

[0001] The invention belongs to the technical field of experimental devices, and in particular relates to a device and method for measuring thermal insulation temperature rise of concrete. Background Art

[0002] The influence of concrete's heat release performance on the durability of concrete structures has been increasingly valued, especially the temperature rise of large-volume concrete has long been a concern. According to the definition in JG / T55-2000 "General Concrete Mix Design Code", large-volume concrete refers to a concrete structure whose minimum physical entity size is equal to or greater than 1 meter, or a concrete structure that is expected to crack due to excessive temperature difference between the inside and outside of the concrete caused by cement hydration heat. At present, it is found in actual engineering that many concrete structures that were previously thought to be unnecessary to pay attention to often crack due to temperature rise. Therefore, the American Concrete Institute also believes that any cast-in-place concrete that has a size that must solve the problem of hydration heat and the resulting volume deformation to minimize its impact on cracking can be called large-volume concrete, and temperature control measures must be taken. Therefore, it can be seen that the temperature rise of concrete has always been a concern at home and abroad. Determining the adiabatic temperature rise of concrete can evaluate the hydration heat release capacity of concrete.

[0003] At present, the common method for measuring the adiabatic temperature rise of concrete is mainly a concrete adiabatic temperature measuring device, which consists of an adiabatic curing box with a rectangular or cylindrical shape and a sample barrel with a matching internal shape. The adiabatic box completely wraps the sample barrel and is arranged in a "U"-shaped structure. The adiabatic curing box provides an insulating environment to ensure that the sample does not exchange heat with the outside. The thermometer in the adiabatic chamber and the thermometer arranged on the sample monitor the temperature of the adiabatic chamber and the sample in real time, and input the data into the computer for feedback control, and finally obtain the temperature-time curve.

[0004] The curve obtained by this measurement method can quantitatively describe the temperature change of concrete during adiabatic heating, but the measurement accuracy is low. The main reasons are as follows:

[0005] 1) Sample shape. The sample tube is generally a cuboid or a cylinder. The distances from each point on the cuboid cross-section boundary to the geometric center are not the same, and the thermal boundary conditions of each geometric boundary are inconsistent, resulting in uneven temperature inside the sample. The temperature measurement point data is largely related to its position and is not the actual sample temperature.

[0006] 2) Insulation environment. The so-called insulation system is a system that does not exchange heat with the outside world. It is an ideal physical model. According to the principles of thermodynamics, temperature difference is a necessary and sufficient condition for heat exchange. Therefore, the insulation box can isolate heat transfer by ensuring that the temperature inside and outside the sample tube is consistent. At present, the insulation box is mainly made of steel plates, and the thermal conductivity coefficient is relatively large; because a heater is required to control the temperature of the insulation chamber, there is air flow in the insulation chamber; the temperature is controlled by monitoring the insulation chamber and the sample temperature feedback adjustment, and there are problems such as the temperature measurement accuracy being affected by the position of the measuring point, the heating and temperature control response is slow, the temperature control accuracy is poor, and the heating is uneven. The above factors all affect the insulation effect.

[0007] 3) Test time. With the increase of fly ash and other admixtures in concrete, the adiabatic temperature rise of concrete in the later stage will increase significantly. At present, the adiabatic temperature rise test is only carried out for 28 days, and the temperature rise rate of concrete in the later stage is slow, and the test accuracy is difficult to guarantee. Summary of the invention

[0008] In order to solve the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide a concrete insulation temperature rise measurement device and method, which has good insulation effect, the measured temperature is closer to the actual value, and can perform high-precision measurements in long-term tests, providing an important basis for theoretical analysis and engineering practice.

[0009] The present invention is achieved through the following technical solutions:

[0010] The invention discloses a concrete adiabatic temperature rise measuring device, comprising a sample tube, an insulation box and a temperature measuring insert; the sample tube and the insulation box are both spherical, the sample tube is nested inside the insulation box, and there is a vacuum between the sample tube and the insulation box; an insulation layer is arranged outside the insulation box; one end of a plurality of temperature measuring inserts is connected to the sample tube, and the other ends are distributed on a spherical surface inside the sample tube that is concentric with the sample tube;

[0011] An internal temperature measuring device is arranged inside the temperature measuring tube, and an external temperature measuring device and a heating device are arranged on the outer wall of the sample tube. The internal temperature measuring device, the external temperature measuring device and the heating device are respectively connected to the data acquisition and control system.

[0012] Preferably, the insulation box is multi-layered, and there is a vacuum between adjacent insulation boxes.

[0013] Preferably, the sample tube and the insulation box are made of heat-insulating materials.

[0014] Preferably, the sample tube comprises a lower hemisphere, an upper hemisphere and a top cover; the lower hemisphere is detachably connected to the upper hemisphere, the upper hemisphere is detachably connected to the top cover, one end of a plurality of temperature measuring inserts is connected to the top cover, and the other ends are evenly distributed on a spherical surface concentric with the sample tube;

[0015] The heat-insulating box comprises a lower hemisphere, an upper hemisphere and a top cover; the lower hemisphere is detachably connected to the upper hemisphere, and the upper hemisphere is detachably connected to the top cover;

[0016] A plurality of pillars are connected between the lower hemisphere of the cylinder and the lower hemisphere of the box.

[0017] Further preferably, sealing gaskets are provided between the lower hemisphere of the cylinder and the upper hemisphere of the cylinder, between the upper hemisphere of the cylinder and the cylinder top cover, between the lower hemisphere of the box and the upper hemisphere of the box, and between the upper hemisphere of the box and the box top cover.

[0018] Preferably, a socket and an exhaust valve are provided on the top cover of the box, the socket is connected to the temperature measuring device inside the cylinder, the temperature measuring device outside the cylinder and the heating device, and a pressure detection device is provided on the exhaust valve.

[0019] Further preferably, the socket is an aviation socket.

[0020] Preferably, the temperature measuring cannula comprises a connecting tube and a temperature measuring tip, one end of the connecting tube is connected to the sample tube, and the other end is detachably connected to the temperature measuring tip, and the temperature measuring device in the tube is connected to the temperature measuring tip.

[0021] Further preferably, the material of the connecting tube is a heat-insulating material, and the material of the temperature measuring tip is a temperature-sensitive material.

[0022] The present invention discloses a method for measuring the adiabatic temperature rise of concrete by using the above-mentioned concrete adiabatic temperature rise measuring device, comprising:

[0023] Concrete is injected into the sample cylinder, a temperature measuring device inside the cylinder is placed inside the temperature measuring insert, the temperature measuring device inside the cylinder, the temperature measuring device outside the cylinder and the heating device are connected to the data acquisition and control system respectively, the sample cylinder is sealed as a whole and then placed in an insulation box; the insulation box and the sample cylinder are vacuumized and then sealed as a whole;

[0024] The temperature measuring device inside the cylinder reads the internal temperature of the concrete in real time, and the temperature measuring device outside the cylinder reads the temperature outside the sample cylinder in real time. The data acquisition and control system compares the two temperature differences with the preset threshold after reading and comparing them. When the temperature difference exceeds the threshold, the data acquisition and control system controls the heating device to start heating until the temperature difference does not exceed the threshold.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention discloses a concrete adiabatic temperature rise measuring device. The sample tube and the insulation box adopt a spherical structure, which is convenient for nesting and assembly. More importantly, each position of the spherical surface is equivalent, the temperature is expressed evenly, and the temperature measuring end of the temperature measuring insert is distributed on the spherical surface concentric with the sample tube, which can obtain accurate temperature values ​​with uniform expression, and at the same time reduce the reading difference caused by different arrangement positions. There is a vacuum between the sample tube and the insulation box, which can reduce the heat transfer between the concrete sample and the external environment, improve the insulation effect, and the insulation layer outside the insulation box further improves the insulation effect. When there is a temperature difference between the inside and outside of the sample tube, the temperature outside the sample tube can be increased by the heating device to make up for the temperature difference between the inside and outside, ensure the insulation of the test process, and improve the test accuracy. During the test, the temperature data inside and outside the sample tube and the opening and closing of the heating device are collected through the data acquisition and control system, which has a high degree of automation, reduces labor, and can perform high-precision measurements in long-term tests, providing an important basis for theoretical analysis and engineering practice.

[0027] Furthermore, the insulation box adopts a multi-layer structure, and there is a vacuum between adjacent insulation boxes, which can meet the test occasions with higher insulation requirements.

[0028] Furthermore, the material of the sample tube and the insulation box is a heat-insulating material, which can enhance the heat-insulating effect and improve the accuracy of the test data.

[0029] Furthermore, the sample tube and the insulation box adopt an upper and lower hemisphere structural design, which is convenient for nesting, assembly and disassembly.

[0030] Furthermore, sealing gaskets are arranged at the connections between the components to ensure sealing and improve the thermal insulation effect.

[0031] Furthermore, the temperature measuring device inside the cylinder, the temperature measuring device outside the cylinder and the heating device are integrated at the socket, which reduces the complicated operation of wiring and facilitates the integration and plugging of the lines. The pressure detection device can monitor the vacuum degree in real time and can also inflate and cool the insulation box when necessary.

[0032] Furthermore, the socket adopts an aviation socket, which has fast connection and good reliability.

[0033] Furthermore, the temperature measuring insert adopts a detachable connecting tube and a temperature measuring tip structure, which is convenient for manufacturing and maintenance.

[0034] Furthermore, the connecting tube is made of heat-insulating material and the temperature measuring tip is made of temperature-sensitive material, which can ensure that the internal cylinder temperature measuring device can accurately collect the temperature of the temperature measuring point through the temperature measuring tip, thereby improving the accuracy of the data.

[0035] The method for measuring the adiabatic temperature rise of concrete using the above-mentioned concrete adiabatic temperature rise measuring device disclosed in the present invention can ensure high-precision measurement by compensating for the internal and external temperature difference during long-term tests, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 An exploded view of the concrete insulation temperature rise measuring device of the present invention;

[0037] Figure 2 This is a diagram showing the effect of using the concrete insulation temperature rise measuring device of the present invention;

[0038] Figure 3 It is a schematic diagram of the device of the temperature measuring cannula of the present invention;

[0039] Figure 4 This is a block diagram of the measurement principle of the present invention.

[0040] In the figure: 1-sample cylinder, 1-1-lower hemisphere of cylinder, 1-2-upper hemisphere of cylinder, 1-3-top cover of cylinder, 2-insulating box, 2-1-lower hemisphere of box, 2-2-upper hemisphere of box, 2-3-top cover of box, 3-temperature measuring insert, 3-1-connecting pipe, 3-2-temperature measuring tip, 4-temperature measuring device inside cylinder, 5-temperature measuring device outside cylinder, 6-heating device, 7-data acquisition and control system. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, the contents of which are intended to explain the present invention rather than to limit it:

[0042] The concrete adiabatic temperature rise measuring device of the present invention comprises a sample tube 1, an insulation box 2 and a temperature measuring insert 3; Figure 2 The sample tube 1 and the insulation box 2 are both spherical and simple pressure vessels, designed and manufactured in accordance with the relevant national standards; the sample tube 1 is nested inside the insulation box 2, and there is a vacuum between the sample tube 1 and the insulation box 2; according to the insulation requirements, multiple layers of insulation boxes 2 can be set, and there is a vacuum between adjacent insulation boxes 2. The sample tube 1 and the insulation box 2 are made of insulation materials, such as G10 glass fiber and resin rolled composite materials, polytetrafluoroethylene, etc. An insulation layer is provided on the outside of the insulation box 2, and the insulation layer is made of materials with good thermal insulation effect and soft texture, such as cotton, foam plastics, etc.

[0043] One end of a plurality of temperature measuring cannulas 3 is connected to the sample tube 1, and the other end is distributed on a spherical surface inside the sample tube 1 and concentric with the sample tube 1. Figure 3In a preferred embodiment of the present invention, the temperature measuring cannula 3 includes a connecting tube 3-1 and a temperature measuring tip 3-2. One end of the connecting tube 3-1 is connected to the sample tube 1, and the other end is connected to the temperature measuring tip 3-2 by a thread. The temperature measuring device 4 in the tube is connected to the temperature measuring tip 3-2. The connecting tube 3-1 is made of a heat-insulating material, preferably polytetrafluoroethylene, and the temperature measuring tip 3-2 is made of a temperature-sensitive material, preferably copper.

[0044] The temperature measuring cannula 3 is provided with an inner tube temperature measuring device 4, and the outer tube temperature measuring device 5 and the heating device 6 are provided on the outer wall of the sample tube 1. The inner tube temperature measuring device 4, the outer tube temperature measuring device 5 and the heating device 6 are respectively connected to the data acquisition and control system 7. The data acquisition and control system 7 includes a data acquisition card and a host computer. The host computer has built-in data processing software, such as LabVIEW. The data acquisition card can read the readings of the inner tube temperature measuring device 4 and the outer tube temperature measuring device 5 and convert them into electrical signals and transmit them to the host computer. After being processed by the data processing software, the host computer transmits the control signal to the data acquisition card, and controls the heating degree by controlling the working voltage and current of the heating device 6.

[0045] like Figure 1 In a preferred embodiment of the present invention, the sample tube 1 includes a lower hemisphere 1-1, an upper hemisphere 1-2 and a top cover 1-3; the lower hemisphere 1-1 and the upper hemisphere 1-2 are detachably connected by flanges and connecting bolts, the upper hemisphere 1-2 and the top cover 1-3 are detachably connected by flanges and connecting bolts, one end of a plurality of temperature measuring inserts 3 is connected to the top cover 1-3, and the other end is evenly distributed on a spherical surface concentric with the sample tube 1; a handle is provided on the side of the upper hemisphere 1-2. The insulation box 2 includes a lower hemisphere 2-1, an upper hemisphere 2-2 and a top cover 2-3; the lower hemisphere 2-1 and the upper hemisphere 2-2 are detachably connected by flanges and connecting bolts, the upper hemisphere 2-2 and the top cover 2-3 are detachably connected by flanges and connecting bolts; a handle is provided on the side of the upper hemisphere 2-2. A plurality of pillars are connected between the lower hemisphere 1-1 of the cylinder and the lower hemisphere 2-1 of the box, and a concentric fixed connection is achieved through one-to-one correspondence of the fulcrums on the outer walls of the lower hemisphere 1-1 of the cylinder and the lower hemisphere 2-1 of the box.

[0046] In order to improve the sealing performance of the device, sealing gaskets can be arranged between the lower hemisphere 1-1 and the upper hemisphere 1-2, between the upper hemisphere 1-2 and the top cover 1-3, between the lower hemisphere 2-1 and the upper hemisphere 2-2, and between the upper hemisphere 2-2 and the top cover 2-3. The top cover 2-3 is provided with a socket and an air extraction valve, the temperature measuring device 4 inside the cylinder, the temperature measuring device 5 outside the cylinder and the heating device 6 are integrated on the socket, the socket is preferably an aviation socket, and the air extraction valve is provided with a pressure detection device for monitoring the vacuum degree, and can also be used to inflate and cool the insulated box.

[0047] The method for measuring the adiabatic temperature rise of concrete using the above-mentioned concrete adiabatic temperature rise measuring device comprises:

[0048] Before the test, each component is in a separated state to facilitate necessary inspection and cleaning. The number of layers of the insulation box 2 required is determined according to the test needs. First, install the lower hemisphere 2-1 of each layer and the lower hemisphere 1-1 of the tube in sequence, connect the lower hemisphere 1-1 of the tube with the upper hemisphere 1-2, inject concrete into the sample tube 1, place the temperature measuring device 4 in the tube inside the temperature measuring insert 3, and seal the tube top cover 1-3 fixed with the temperature measuring insert 3 with the upper hemisphere 1-2 of the tube. The temperature measuring device 4 in the tube, the temperature measuring device 5 outside the tube and the heating device 6 are connected separately, the external power supply and the data acquisition and control system 7 are connected to the socket, the upper hemisphere 2-2 of the box is connected to the lower hemisphere 2-1 of the box, and then the box top cover 2-3 is connected to the upper hemisphere 2-2 of the box; vacuum the insulation box 2 and the sample tube 1 through the exhaust valve and seal the whole, and close the exhaust valve.

[0049] Generally speaking, due to the solidification and heating of concrete, the temperature inside the sample tube 1 is always higher than the temperature outside the tube. This temperature difference will cause the concrete to dissipate heat spontaneously. Heat dissipation means no insulation, so preventing heat dissipation is the key to insulation testing. During the test, the multi-layer insulation box 2, vacuum environment and insulation layer work together to largely prevent the sample from dissipating heat outward.

[0050] The temperature measuring device 4 inside the cylinder reads the internal temperature of the concrete in real time, and the temperature measuring device 5 outside the cylinder reads the temperature outside the sample cylinder 1 in real time. The data acquisition and control system 7 compares the two temperature differences with the preset threshold value after reading and comparing them. When the temperature difference exceeds the threshold value, such as 0.1°C, the data acquisition and control system 7 controls the heating device 6 to start heating to compensate for the temperature difference between the inside and the outside until the temperature difference does not exceed the threshold value, thereby ensuring the insulation of the test process and obtaining more accurate results.

[0051] When the test is completed, the whole set of equipment only needs to be disassembled, and the concrete in the sample tube 1 can be cleaned out before the next test.

[0052] It should be noted that the above is only a part of the implementation of the present invention, and equivalent changes made to the system described in the present invention are all included in the protection scope of the present invention. Those skilled in the art of the present invention can replace the specific examples described in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they all belong to the protection scope of the present invention.

Claims

1. A concrete adiabatic temperature rise measuring device, characterized in that: The invention comprises a sample tube (1), an insulating box (2) and a temperature measuring insert (3); the sample tube (1) and the insulating box (2) are both spherical, the sample tube (1) is nested inside the insulating box (2), and a vacuum is provided between the sample tube (1) and the insulating box (2); a heat insulating layer is provided outside the insulating box (2); one end of a plurality of temperature measuring inserts (3) is connected to the sample tube (1), and the other end is distributed on a spherical surface inside the sample tube (1) and concentric with the sample tube (1); An internal temperature measuring device (4) is provided inside the temperature measuring tube (3), and an external temperature measuring device (5) and a heating device (6) are provided on the outer wall of the sample tube (1). The internal temperature measuring device (4), the external temperature measuring device (5) and the heating device (6) are respectively connected to a data acquisition and control system (7); The sample tube (1) comprises a lower hemisphere (1-1), an upper hemisphere (1-2) and a top cover (1-3); the lower hemisphere (1-1) and the upper hemisphere (1-2) are detachably connected, the upper hemisphere (1-2) and the top cover (1-3) are detachably connected, one end of a plurality of temperature measuring inserts (3) is connected to the top cover (1-3), and the other end is evenly distributed on a spherical surface concentric with the sample tube (1); The heat-insulating box (2) comprises a box lower hemisphere (2-1), a box upper hemisphere (2-2) and a box top cover (2-3); the box lower hemisphere (2-1) and the box upper hemisphere (2-2) are detachably connected, and the box upper hemisphere (2-2) and the box top cover (2-3) are detachably connected; A plurality of pillars are connected between the lower hemisphere of the cylinder (1-1) and the lower hemisphere of the box (2-1); The temperature measuring insert (3) comprises a connecting tube (3-1) and a temperature measuring tip (3-2); one end of the connecting tube (3-1) is connected to the sample tube (1), and the other end is detachably connected to the temperature measuring tip (3-2); and the temperature measuring device (4) in the tube is connected to the temperature measuring tip (3-2).

2. The concrete adiabatic temperature rise measuring device according to claim 1 is characterized in that: The insulation box (2) is multi-layered, and there is a vacuum between adjacent insulation boxes (2).

3. The concrete adiabatic temperature rise measuring device according to claim 1 is characterized in that: The sample tube (1) and the insulation box (2) are made of heat-insulating materials.

4. The concrete adiabatic temperature rise measuring device according to claim 1, characterized in that: Sealing gaskets are provided between the lower cylinder hemisphere (1-1) and the upper cylinder hemisphere (1-2), between the upper cylinder hemisphere (1-2) and the cylinder top cover (1-3), between the lower box hemisphere (2-1) and the upper box hemisphere (2-2), and between the upper box hemisphere (2-2) and the box top cover (2-3).

5. The concrete adiabatic temperature rise measuring device according to claim 1, characterized in that: A socket and an air extraction valve are provided on the box top cover (2-3); the socket is connected to a temperature measuring device (4) inside the cylinder, a temperature measuring device (5) outside the cylinder and a heating device (6); and a pressure detection device is provided on the air extraction valve.

6. The concrete insulation temperature rise measuring device according to claim 5, characterized in that: The socket is an aviation socket.

7. The concrete insulation temperature rise measuring device according to claim 1 is characterized in that: The material of the connecting pipe (3-1) is a heat-insulating material, and the material of the temperature measuring tip (3-2) is a temperature-sensitive material.

8. A method for measuring the adiabatic temperature rise of concrete using the concrete adiabatic temperature rise measuring device according to any one of claims 1 to 7, characterized in that: include: Concrete is injected into a sample tube (1), a temperature measuring device (4) inside the tube is placed inside a temperature measuring insert (3), the temperature measuring device (4) inside the tube, the temperature measuring device (5) outside the tube and the heating device (6) are respectively connected to a data acquisition and control system (7), and the sample tube (1) is sealed as a whole and then placed in an insulation box (2); the insulation box (2) and the sample tube (1) are evacuated and then sealed as a whole; The temperature measuring device (4) inside the cylinder reads the temperature inside the concrete in real time, and the temperature measuring device (5) outside the cylinder reads the temperature outside the sample cylinder (1) in real time. The data acquisition and control system (7) reads and compares the two temperature differences and then compares them with a preset threshold value. When the temperature difference exceeds the threshold value, the data acquisition and control system (7) controls the heating device (6) to start heating until the temperature difference does not exceed the threshold value.

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