Testing device and method for separating pressure of concrete pore solution under freezing action

Abstract

The application provides a testing device and method for the separation pressure of a concrete pore solution under freezing action, and relates to the technical field of concrete material research. The testing device for the separation pressure of the concrete pore solution under freezing action comprises a frame body, a first groove is formed in the middle of the frame body, two second grooves are formed at intervals on the two sides of the first groove, the bottoms of the two second grooves are in communication with the first groove, and heat-conducting medium is filled in the first groove and the two second grooves. Two groups of bipolar semiconductors are arranged in the two second grooves, the opposite sides of each group of bipolar semiconductors form a cold surface and a hot surface in response to the excitation of external direct current, and the cold surface is attached to the side of the second groove close to the first groove. A testing mechanism is arranged in the first groove and obtains the separation pressure by testing the height change caused by the separation pressure generated by the freezing of the heat-conducting medium in the first groove by the testing mercury based on the to-be-tested sample of the concrete pore solution.

Description

Technical Field

[0001] This application relates to the technical field of concrete material research, and more specifically, to a testing device and method for testing the separation pressure of concrete pore solution under freezing conditions. Background Technology

[0002] Currently, a large number of experimental studies have been conducted on the freeze-thaw damage of concrete, systematically exploring the performance degradation law and damage mechanism of concrete materials after freeze-thaw damage, and proposing many theoretical models, such as the hydrostatic pressure theoretical model.

[0003] However, most existing theoretical models are based on macroscopic experiments and theoretical derivations, and cannot effectively explain some unique freeze-thaw damage phenomena in concrete materials. For example, freeze-thaw damage occurs in cement paste specimens saturated with liquid benzene, and freeze-thaw damage is more severe in concrete after chloride salt erosion. Several studies have used micromechanical methods to systematically analyze the freezing of salt solutions in the micropores (diameter less than 10 nm) inside concrete, proposing that an unfrozen water film forms between ice crystals in the concrete micropores and the solid wall during freezing, thereby generating separation pressure that causes cracking of the thin-walled concrete. Therefore, research on separation pressure remains at the stage of theoretical calculations and molecular dynamics simulations; there is no convenient experimental equipment to directly measure the separation pressure generated by salt solutions during freezing. Summary of the Invention

[0004] To address at least one of the technical problems in the prior art, embodiments of this application provide a testing device and method for measuring the separation pressure of concrete pore solution under freezing conditions, which can directly obtain the separation pressure generated by the concrete pore solution sample during the freezing process.

[0005] An embodiment of this application provides a testing device for the separation pressure of concrete pore solution under freezing action, comprising: a frame, a first groove formed in the middle of the frame, two second grooves formed at intervals on both sides of the first groove, and the bottoms of the two second grooves communicating with the first groove, and a heat-conducting medium filled in the first groove and the two second grooves; two sets of bipolar semiconductors, respectively disposed in the two second grooves, each set of bipolar semiconductors having opposite sides configured to form a cold surface and a hot surface respectively in response to external DC current excitation, the cold surface being in contact with the side of the second groove near the first groove to exchange heat with the heat-conducting medium in the first groove; and a testing mechanism disposed in the first groove and configured to obtain the separation pressure by measuring the height change caused by the separation pressure generated when a test sample based on mercury in concrete pore solution freezes in the heat-conducting medium in the first groove.

[0006] According to some embodiments of this application, the testing mechanism includes: a test tube filled with the test sample; a pressure measuring tube including: a connecting portion, one end of which is connected to the test tube; and a U-shaped portion having an open end and a closed end, the open end being connected to the other end of the connecting portion, the U-shaped portion being filled with mercury to respond to a significant change in separation pressure caused by the test sample freezing in the heat-conducting medium within the first groove.

[0007] According to some embodiments of this application, the side wall of the frame is provided with a U-shaped groove to accommodate the U-shaped part, thereby facilitating external observation of the mercury height change.

[0008] According to some embodiments of this application, the above-mentioned testing mechanism further includes: a reference plate disposed on one side of the test tube, and a scale is provided on the side of the reference plate facing the test tube; a bracket disposed on the side of the test tube opposite to the reference plate; and a reflector mounted on the bracket to facilitate observation of the thickness of the unfrozen layer of the test sample during the freezing process from above the bracket.

[0009] According to some embodiments of this application, the testing device for the separation pressure of concrete pore solution under freezing further includes: a cover body disposed above the frame body, and the cover body having a window opening at the position facing the first groove, so as to observe the thickness of the unfrozen layer through the reflector and the scale; and a glass plate installed at the window to maintain the temperature inside the first groove.

[0010] According to some embodiments of this application, the testing device for the separation pressure of concrete pore solution under freezing action further includes: a housing having an accommodating space to accommodate the frame and the cover.

[0011] According to some embodiments of this application, the testing device for the separation pressure of concrete pore solution under freezing action further includes: two first fans, respectively disposed at the bottom of the two second grooves, so that the heat-conducting medium in the two second grooves exchanges heat with the heat-conducting medium in the first groove.

[0012] According to some embodiments of this application, the housing has two openings on the two sidewalls facing the hot surfaces of the two sets of bipolar semiconductors, and the test device further includes two second fans, which are respectively installed in the two openings to dissipate heat from the hot surfaces of the two sets of bipolar semiconductors.

[0013] According to some embodiments of this application, the testing device for the separation pressure of concrete pore solution under freezing action further includes: at least one temperature sensor disposed on the side wall of the first groove to detect the temperature inside the first groove.

[0014] According to some embodiments of another aspect of this application, a method for testing the separation pressure of concrete pore solution under freezing action is also provided, applicable to the aforementioned testing device for the separation pressure of concrete pore solution under freezing action. The testing method includes: injecting a test sample containing concrete pore solution into a test tube, and installing the test tube containing the test sample into a first groove of a frame; connecting the connecting part of the pressure measuring tube to the top of the test tube; injecting a heat-conducting medium into the first groove and two second grooves of the frame, and covering the top of the frame with a cover; recording the initial height of the mercury column in the U-shaped part of the pressure measuring tube when the test tube is at room temperature and pressure; turning on two first fans and two second fans, and adjusting the magnitude of the DC current applied to the bipolar semiconductor to make the temperature of the heat-conducting medium in the first groove reach the target temperature; observing the thickness of the unfrozen layer of the test sample during the freezing process through a reflector, and recording the measured height of the mercury column in the U-shaped part; and obtaining the separation pressure generated by the test sample freezing in the heat-conducting medium in the first groove based on the initial height and the measured height.

[0015] The testing device and method for measuring the separation pressure of concrete pore solution under freezing according to embodiments of this application involve attaching the cold surfaces of two sets of bipolar semiconductors to the sides of two second grooves near the first groove. This allows the cooling energy generated by the bipolar semiconductors under DC excitation to be directly transferred to the heat-conducting medium within the second grooves. Furthermore, the heat-conducting medium circulates throughout the entire frame via the connected first and two second grooves, achieving uniform cooling of the heat-conducting medium within the first groove. This precisely controls the freezing temperature of the concrete pore solution sample and improves cooling efficiency. By testing the height change caused by the separation pressure generated when mercury-based concrete pore solution samples freeze in the heat-conducting medium within the first groove, the separation pressure generated by the freezing of the test sample can be determined from the height change of the mercury column, based on the principles of fluid statics. This reveals the mechanism of concrete freeze-thaw damage from a microscopic perspective. Attached Figure Description

[0016] Figure 1 This is a perspective view of a testing device for the separation pressure of concrete pore solution under freezing action according to an illustrative embodiment of this application;

[0017] Figure 2 This is an exploded view of the components of a testing device for the separation pressure of concrete pore solution under freezing action, according to an illustrative embodiment of this application.

[0018] Figure 3 This is a partial perspective view of a frame according to an illustrative embodiment of the present application, showing a first groove and two second grooves of the frame, a temperature sensor and two sets of bipolar semiconductors in the first groove;

[0019] Figure 4 This is a partial perspective view of a frame according to an illustrative embodiment of the present application, showing the test mechanism and two first fans;

[0020] Figure 5 This is a perspective view of the cover and glass plate according to an illustrative embodiment of this application;

[0021] Figure 6 This is a perspective view of a housing according to an illustrative embodiment of the present application;

[0022] Figure 7 This is a side view of a test device for the separation pressure of concrete pore solution under freezing action according to an illustrative embodiment of this application, under normal temperature and pressure conditions.

[0023] Figure 8 This is a side view of the test tube and the pressure measuring tube under the condition that the test tube is at the target temperature according to an illustrative embodiment of this application;

[0024] Figure 9 This is a flowchart of a method for testing the separation pressure of concrete pore solution under freezing conditions according to an illustrative embodiment of this application.

[0025] The meanings of the reference numerals in the attached figure are as follows:

[0026] 1. Shell;

[0027] 100. Observation mirror;

[0028] 2. Cover;

[0029] 3. Glass plate;

[0030] 4. Frame;

[0031] 41. First groove;

[0032] 42. Second groove;

[0033] 5. Bipolar semiconductor;

[0034] 6. Testing organization;

[0035] 61. Test tube;

[0036] 611. First mounting base;

[0037] 612. Pipe opening;

[0038] 62. Pressure testing tube;

[0039] 621. Connecting part;

[0040] 622. U-shaped section;

[0041] 63. Reference plate;

[0042] 631. Second mounting bracket;

[0043] 64. Bracket;

[0044] 65. Reflector;

[0045] 7. First fan;

[0046] 8. Second fan;

[0047] 9. Temperature sensor.

[0048] 10. Temperature control module. Detailed Implementation

[0049] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0050] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0051] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0052] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0053] Figure 1 This is a perspective view of a testing device for the separation pressure of concrete pore solution under freezing action, according to an illustrative embodiment of this application. Figure 2 This is an exploded view of the components of a testing device for the separation pressure of concrete pore solution under freezing conditions, according to an illustrative embodiment of this application. Figure 3 This is a partial perspective view of a frame according to an illustrative embodiment of the present application, showing a first groove and two second grooves of the frame, a temperature sensor (which will be described in detail below) in the first groove, and two sets of bipolar semiconductors.

[0054] An embodiment of this application provides a testing device for the separation pressure of concrete pore solution under freezing conditions, such as... Figure 1 , Figure 2 and Figure 3 As shown, the testing device includes a frame 4, two sets of bipolar semiconductors 5, and a testing mechanism 6. A first groove 41 is formed in the middle of the frame 4. Two second grooves 42 are formed at intervals on both sides of the first groove 41, and the bottoms of both second grooves 42 are connected to the first groove 41. Both the first groove 41 and the two second grooves 42 are filled with a heat-conducting medium. The two sets of bipolar semiconductors 5 are respectively disposed in the two second grooves 42. The opposite sides of each set of bipolar semiconductors 5 are configured to form a cold surface and a hot surface respectively in response to the excitation of an external direct current. The cold surface is in contact with the side of the second groove 42 near the first groove 41 to exchange heat with the heat-conducting medium in the first groove 41. The testing mechanism 6 is disposed in the first groove 41 and is configured to obtain the separation pressure by measuring the height change caused by the separation pressure generated when the test sample (based on a concrete pore solution of test mercury) freezes in the heat-conducting medium in the first groove 41.

[0055] In some illustrative embodiments, the heat-conducting medium in the first groove 41 and the two second grooves 42 can be a solution with good thermal conductivity, such as anhydrous ethanol.

[0056] In some illustrative embodiments, the opposite sides of each set of bipolar semiconductors 5 form a cold surface and a hot surface respectively in response to different external DC current excitations. The cold surface is in contact with the side of the second groove 42 near the first groove 41 to exchange heat with the heat-conducting medium in the first groove 41. The internal temperature of the first groove 41 is precisely adjusted by controlling the voltage of the bipolar semiconductors 5, with a temperature control accuracy of ±0.1℃, achieving the cooling temperature requirement of -30℃ to 0℃. The freezing of concrete pore solution at different temperatures can be effectively simulated in the first groove 41.

[0057] In this implementation, by attaching the cold surfaces of the two sets of bipolar semiconductors 5 to the sides of the two second grooves 42 near the first groove 41, the cooling energy generated by the bipolar semiconductors 5 under DC excitation can be directly transferred to the heat-conducting medium in the second grooves 42. Furthermore, through the connection between the first groove 41 and the two second grooves 42, the heat-conducting medium circulates throughout the entire frame 4, achieving uniform cooling of the heat-conducting medium in the first groove 41. This precisely controls the freezing temperature of the concrete pore solution sample and improves cooling efficiency. By testing the height change caused by the separation pressure generated when mercury-based concrete pore solution samples freeze in the heat-conducting medium within the first groove 41, according to the principles of fluid statics, the separation pressure generated by the freezing of the test sample can be determined from the height change of the mercury column, revealing the mechanism of concrete freeze-thaw damage from a microscopic perspective.

[0058] Figure 4 This is a partial perspective view of a frame according to an illustrative embodiment of the present application, showing the test mechanism and two first fans (the first fans will be described in detail below).

[0059] According to embodiments of this application, such as Figure 4 As shown, the testing mechanism includes a test tube 61 and a pressure measuring tube 62. The test tube 61 is filled with the sample to be tested. The pressure measuring tube 62 includes a connecting portion 621 and a U-shaped portion 622. One end of the connecting portion 621 is connected to the test tube 61. The U-shaped portion 622 has an open end and a closed end, the open end of which is connected to the other end of the connecting portion 621. The U-shaped portion 622 is filled with mercury to accommodate a significant change in separation pressure in response to the sample freezing in the heat-conducting medium within the first groove 41.

[0060] In some illustrative embodiments, the test tube 61 is fixed to the bottom of the first groove 41 by a first mounting base 611.

[0061] In some illustrative embodiments, the test tube 61 can be a transparent glass capillary. When simulating real concrete micropores, a layer of concrete-like material, such as a thin layer of tobermorite, can be processed on the inner wall of the transparent glass capillary. This largely simulates the situation of micropores (diameter less than 10 nm) inside concrete, facilitating the investigation of the freezing of concrete pore solutions under different low-temperature conditions.

[0062] In some illustrative embodiments, one end of the connector 621 is connected to the test tube 61 via the port 612.

[0063] In some illustrative embodiments, the U-shaped portion 622 can be a glass U-tube. The open end is connected to the other end of the connecting portion 621, the bottom of the U-shaped portion 622 is filled with mercury, and the closed end is a closed vacuum section, maintaining an absolute pressure of zero at the closed end.

[0064] In this embodiment, by placing the test tube 61 within the heat-conducting medium in the first groove 41, the test sample inside the test tube 61 can be uniformly cooled and frozen. By providing the U-shaped portion 622 of the pressure measuring tube 62, when the test sample inside the test tube 61 generates separation pressure during the freezing process, this pressure is transmitted to the U-shaped portion 622 via the connecting portion 621, causing a change in the height of the mercury column within the U-shaped portion 622. According to the principles of fluid statics, the separation pressure can be determined from the height difference of the mercury column. By processing the inner wall of the test tube 61 with a concrete-like material, the interfacial characteristics of concrete micropores can be more realistically simulated, improving the accuracy of the test results.

[0065] According to an embodiment of this application, the side wall of the frame 4 is provided with a U-shaped groove to accommodate the U-shaped part 622, thereby facilitating external observation of the mercury height change.

[0066] In some illustrative embodiments, the side wall of the frame 4 is provided with a U-shaped groove, the shape of which matches the shape of the U-shaped part 622. The U-shaped groove is used to accommodate the U-shaped part 622, so that the side of the U-shaped part 622 away from the test tube 61 is exposed to the external view of the frame 4.

[0067] In this embodiment, by creating a U-shaped groove that matches the shape of the U-shaped part 622, the U-shaped part 622 can be embedded and fixed to the side wall of the frame 4. Simultaneously, the side of the U-shaped part 622 furthest from the test tube 61 is exposed to the external view of the frame 4, allowing operators to directly observe the height change of the mercury column within the U-shaped part 622 without disassembling the testing device. According to the principle of hydrostatic equilibrium, when the test sample in the test tube 61 generates separation pressure during freezing, this pressure is transmitted to the U-shaped part 622 via the connecting part 621, causing a change in the height of the mercury column within the U-shaped part 622. The separation pressure can be determined by externally observing the height difference of the mercury column. Positioning the U-shaped part 622 within the U-shaped groove on the side wall of the frame 4 also maintains its vertical position during observation, avoiding reading errors caused by tilting and thus improving measurement accuracy.

[0068] According to embodiments of this application, such as Figure 4 As shown, the testing mechanism also includes a reference plate 63, a bracket 64, and a reflector 65. The reference plate 63 is disposed on one side of the test tube 61, and a scale is provided on the side of the reference plate 63 facing the test tube 61. The bracket 64 is disposed on the side of the test tube 61 opposite to the reference plate 63. The reflector 65 is mounted on the bracket 64 to facilitate observation of the thickness of the unfrozen layer of the test sample during the freezing process from above the frame 4.

[0069] In some illustrative embodiments, the reference plate 63 is fixed to the bottom of the first groove 41 by the second mounting base 631 and is located on one side of the test tube 61. The reference plate 63 is an opaque and waterproof plate, and a standard scale with units in nanometers (nm) is provided on the side of the reference plate 63 facing the test tube 61.

[0070] In some illustrative embodiments, a reflector 65 is mounted on a bracket 64. The angle of the reflector 65 can be adjusted according to actual test requirements to reflect the light propagating from the direction of the test tube 61 to the top of the frame 4. The thickness of the unfrozen layer of the test sample during the freezing process can be observed from the top of the frame 4. The thickness of the unfrozen layer can be measured by a ruler on the reference plate 63.

[0071] In this implementation, a reference plate 63 is placed on one side of the test tube 61, and a scale is set on the side of the reference plate 63 facing the test tube 61, providing a standard length reference for observing the thickness of the unfrozen layer. A bracket 64 is set on the other side of the test tube 61, and a reflector 65 is installed. Utilizing the adjustable angle of the reflector 65, light from the direction of the test tube 61 is reflected and propagates vertically to the top of the frame 4. Using an optical microscope mounted on the top of the frame 4, the operator can obtain a clear image of the test sample inside the test tube 61 during the freezing process through the reflector 65, and compare the image with the scale on the reference plate 63, thereby achieving non-contact, precise measurement of the unfrozen layer thickness. By measuring the unfrozen layer thickness under different temperature conditions and combining it with simultaneously measured separation pressure data, a quantitative relationship between the unfrozen layer thickness and separation pressure can be established, thus providing experimental evidence for analyzing the impact mechanism of concrete pore solution freezing on concrete freeze-thaw damage.

[0072] Figure 5 This is a perspective view of the cover and glass plate according to an illustrative embodiment of this application.

[0073] According to embodiments of this application, such as Figure 2 , Figure 4 and Figure 5 As shown, the testing device for the separation pressure of concrete pore solution under freezing conditions also includes a cover 2 and a glass plate 3. The cover 2 is positioned above the frame 4, and a window is provided on the cover 2 facing the first groove 41 to facilitate observation of the thickness of the unfrozen layer through a reflector 65 and a ruler. The glass plate 3 is installed at the window to maintain the temperature within the first groove 41.

[0074] In some illustrative embodiments, the two sides of the glass plate 3 are treated with a special process to reduce the accumulation of condensed liquid in the glass plate 3 when there is a large temperature difference between the front and back of the glass plate 3.

[0075] In this implementation, by opening a window in the cover 2 and installing a glass plate 3, the cover 2 can seal the opening above the first groove 41, thereby maintaining the temperature stability of the heat-conducting medium inside the first groove 41 and reducing interference from the external ambient temperature on the experiment. Special processing is applied to both sides of the glass plate 3 to prevent condensation from accumulating on the surface of the glass plate 3 due to excessive temperature difference between the front and back of the cover 2, thus avoiding the impact of condensation droplets on the clarity of optical observation. By opening a window in the cover 2 corresponding to the first groove 41 and installing an anti-condensation glass plate 3, light from the external optical microscope can be reflected by the reflector 65 and pass through the glass plate 3 into the observation optical path. Simultaneously, the operator can use the window, reflector 65, and scale on the reference plate 63 to perform non-contact measurement of the thickness of the unfrozen layer of the test sample in the test tube 61 inside the first groove 41 during the freezing process.

[0076] Figure 6 This is a perspective view of a housing according to an illustrative embodiment of the present application.

[0077] According to embodiments of this application, such as Figure 6 As shown, the test device for the separation pressure of concrete pore solution under freezing action also includes a housing 1, which has a accommodating space to accommodate the frame 4 and the cover 1.

[0078] In some illustrative embodiments, an observation mirror 100 is provided on the side wall of the housing 1 facing the U-shaped part 622. The observation mirror 100 is provided with scale lines to facilitate real-time direct observation of the changes in the height of the mercury column.

[0079] In some illustrative embodiments, a current conversion mechanism is provided at the bottom of the housing 1. The current conversion mechanism is electrically connected to two sets of bipolar semiconductors 5. The current conversion mechanism is suitable for converting external alternating current into direct current.

[0080] In some illustrative embodiments, the material of the housing 1 may be metal.

[0081] In this implementation, by providing a housing 1 with a accommodating space, the frame 4 and cover 1 are housed within the accommodating space, forming a closed structure for the entire testing device. This reduces interference from the external environment on the testing process and improves the compactness and portability of the testing device. A converter mechanism is installed at the bottom of the housing 1 to convert external alternating current into direct current to supply the two sets of bipolar semiconductors 5, meeting the direct current requirements of the two sets of bipolar semiconductors 5 and ensuring that the two sets of bipolar semiconductors 5 can operate normally and achieve the cooling function.

[0082] According to embodiments of this application, such as Figure 2 and Figure 4As shown, the test device for the separation pressure of concrete pore solution under freezing action also includes two first fans 7, which are respectively set at the bottom of two second grooves 42, so that the heat-conducting medium in the two second grooves 42 can exchange heat with the heat-conducting medium in the first groove 41.

[0083] In some illustrative embodiments, the two first fans 7, when in operation, cause the heat-conducting medium in the two second grooves 42 to flow and exchange heat with the heat-conducting medium in the first groove 41.

[0084] In this implementation, by setting two first fans 7 at the bottom of the two second grooves 42 respectively, and activating the two first fans 7 during the operation of the test device, the heat-conducting medium in the two second grooves 42 is forced to flow. Furthermore, by setting the bottom of the two second grooves 42 to be connected to the first groove 41, the heat-conducting medium in the entire frame 4 is driven to form a circulating flow. This allows the cooling energy generated by the cold surface of the bipolar semiconductor 5 to be quickly and evenly transferred to various positions in the first groove 41, avoiding uneven temperature distribution in the first groove 41 due to temperature stratification of the heat-conducting medium. This ensures that the test sample in the test tube 61 is in a uniform and stable temperature field during the freezing process, improving the accuracy and repeatability of the unfrozen layer thickness and separation pressure measurement.

[0085] According to embodiments of this application, such as Figure 2 , Figure 3 and Figure 6 As shown, the housing 1 has two openings on each of its two sidewalls facing the hot surfaces of the two sets of bipolar semiconductors 5. The test apparatus also includes two second fans 8. The two second fans 8 are respectively installed in the two openings to dissipate heat from the hot surfaces of the two sets of bipolar semiconductors 5.

[0086] In some illustrative embodiments, the airflow direction of the two second fans 8 is directed towards the outside of the housing 1, so as to perform convection heat dissipation on the hot surfaces of the two sets of bipolar semiconductors 5 respectively.

[0087] In this implementation, an opening corresponding to the hot surface of the bipolar semiconductor 5 is made in the side wall of the housing 1, and a second fan 8 is installed at the opening. When the second fan 8 operates, it guides external air to flow across the hot surface of the bipolar semiconductor 5, rapidly removing the heat generated by the hot surface through convection heat transfer, thereby effectively reducing the operating temperature of the hot surface. According to the working principle of semiconductor thermoelectric cooling, the heat dissipation efficiency of the hot surface directly affects the cooling effect of the cold surface and the minimum temperature achievable within the first groove 41. By setting the second fan 8 to force heat dissipation from the hot surface, the temperature difference between the hot and cold surfaces can be maintained, thereby ensuring the cooling efficiency of the bipolar semiconductor 5 and enabling the heat-conducting medium within the first groove 41 to stably reach and maintain the low-temperature conditions required for the experiment.

[0088] According to embodiments of this application, such as Figure 3 As shown, the testing device for the separation pressure of concrete pore solution under freezing action also includes at least one temperature sensor 9, which is disposed on the side wall of the first groove 41 to detect the temperature inside the first groove 41.

[0089] In some illustrative embodiments, there may be multiple temperature sensors 9. For example, there may be eight temperature sensors 9, with four temperature sensors 9 forming a group, and two groups respectively disposed on two opposite sidewalls of the first groove 41.

[0090] In some illustrative embodiments, such as Figure 1 , Figure 2 and Figure 6 As shown, a temperature control module 10 is installed on the side wall of the housing 1. The temperature control module 10 is electrically connected to at least one temperature sensor 9, two sets of bipolar semiconductors 5, two first fans 7, and two second fans 8. At least one temperature sensor 9 can detect the actual temperature of the heat-conducting medium in the first groove 41 in real time and can transmit the temperature signal to the temperature control module 10. The temperature control module 10 automatically adjusts the input voltage of the two sets of bipolar semiconductors 5 according to the set temperature value to control the cooling capacity, and at the same time controls the speed of the two first fans 7 and the two second fans 8 to achieve uniform heat transfer and efficient heat dissipation, thereby realizing automatic control of the temperature in the first groove 41.

[0091] In this implementation, by placing at least one temperature sensor 9 on the sidewall of the first groove 41, allowing it to directly contact the heat-conducting medium within the first groove 41, the temperature of the heat-conducting medium within the first groove 41 can be detected in real time. By electrically connecting at least one temperature sensor 9 to the temperature control module 10, the temperature signal collected by the temperature sensor 9 is transmitted to the temperature control module 10. The temperature control module 10 compares the actual temperature with the set temperature value and automatically adjusts the input voltage of the two sets of bipolar semiconductors 5 according to the temperature deviation to control the cooling capacity. Simultaneously, it adjusts the speeds of the two first fans 7 and the two second fans 8, forming a closed-loop feedback control, thereby achieving precise temperature control within the first groove 41. By placing multiple temperature sensors 9 on both sides of the first groove 41, the temperature distribution at different locations within the first groove 41 can be monitored, ensuring the uniformity of the temperature field of the heat-conducting medium within the first groove 41. This, in turn, ensures that the test sample in the test tube 61 undergoes freezing tests under uniform and stable temperature conditions, improving the accuracy and reliability of unfrozen layer thickness and separation pressure measurements.

[0092] Figure 7 This is a side view of a testing device for the separation pressure of concrete pore solution under freezing conditions according to an illustrative embodiment of this application, under normal temperature and pressure. Figure 8This is a side view of the test tube and pressure measuring tube with the test tube at the target temperature according to an illustrative embodiment of this application. Figure 9 This is a flowchart of a method for testing the separation pressure of concrete pore solution under freezing conditions according to an illustrative embodiment of this application.

[0093] According to another embodiment of this application, a method for testing the separation pressure of concrete pore solution under freezing conditions is also provided, applicable to the aforementioned testing device for the separation pressure of concrete pore solution under freezing conditions. First, a concrete pore solution is prepared. After curing, the concrete specimen is removed, and samples are taken from different locations to extract the internal pore solution. The main components and proportions of the pore solution are determined, and a similar concrete pore solution is prepared as the test sample.

[0094] Next, proceed with debugging and preparation. Turn on the power to the testing device and inject anhydrous ethanol into the first groove and two second grooves of the frame 4 to check the overall impermeability of the testing device. Place the testing device under normal temperature (25℃) and normal pressure (standard atmospheric pressure, i.e., 0.1MPa), and record the height of the mercury column in the U-shaped part 622 through the observation mirror, which is recorded as the initial height h0. Debug the two first fans and two second fans to ensure normal operation. Turn on the two sets of bipolar semiconductors 5 and test their cooling function. Use a readable thermometer to calibrate the eight temperature sensors 9 respectively. After debugging, turn off the power to the testing device and pour out the anhydrous ethanol inside the testing device.

[0095] After debugging and preparation are complete, such as Figure 7 , Figure 8 and Figure 9 As shown, the test method includes the following steps S1 to S7.

[0096] Step S1: Inject the test sample of concrete pore solution into the test tube 61, and install the test tube 61 filled with the test sample into the first groove of the frame 4.

[0097] Step S2: Connect the connector 621 of the pressure testing tube to the top of the test tube 61.

[0098] According to an embodiment of this application, one end of the connecting part 621 of the pressure measuring tube is connected to the top of the test tube 61 through the port 612.

[0099] Step S3: Inject heat-conducting medium into the first groove and two second grooves of the frame 4, and cover the top of the frame 4 with the cover 2.

[0100] Place the glass plate 3 on top of the frame 4, then place the cover 2 on top of the glass plate 3. Place the high-powered optical microscope on the glass plate 3 and adjust the angle of the reflector 65 to ensure that the optical microscope can clearly observe the reference plate 63.

[0101] Step S4: Under normal temperature and pressure conditions, record the initial height h0 of the mercury column in the U-shaped part 622 of the pressure measuring tube.

[0102] After completing step S4, turn on the power to the test device.

[0103] Step S5: Turn on the two first fans and the two second fans, and adjust the magnitude of the DC current applied to the bipolar semiconductor so that the temperature of the heat-conducting medium in the first groove reaches the target temperature.

[0104] Step S6: Observe the thickness of the unfrozen layer of the test sample during the freezing process through the reflector 65, and record the measured height h of the mercury column in the U-shaped part 622.

[0105] like Figure 8 As shown, F2 represents the separation pressure generated when the test sample in the test tube 61 freezes in the heat-conducting medium within the first groove. When the test sample of the concrete pore solution freezes at the target temperature, a repulsive force is generated between the unfrozen water film and the ice crystals. This repulsive force acts on the mercury in the U-shaped section 622 through the connecting part 621. F1 represents the pressure exerted by the vacuum environment within the closed end of the U-shaped section 622 on the surface of the mercury column. During the freezing process of the test sample, the separation pressure F2 is transmitted to the mercury column in the U-shaped section 622 through the connecting part 621, causing the mercury column to shift under the pressure difference between F1 and F2. Since F1 is always zero, the change in the height of the mercury column is determined only by the separation pressure F2. By observing the change in the height of the mercury column, combined with the density of mercury and the acceleration due to gravity, the separation pressure generated by the test sample during the freezing process can be determined.

[0106] Step S7: Based on the initial height h0 and the measured height h, obtain the separation pressure generated by the test sample freezing in the heat-conducting medium in the first groove.

[0107] According to an embodiment of this application, based on the height difference between the initial height h0 and the measured height h... The separation pressure F2 and height difference generated by the freezing of the test sample in the heat-conducting medium in the first groove inside the test tube 61 It can be expressed by the following formula (1):

[0108] (1);

[0109] Wherein, F2 represents the separation pressure generated when the test sample freezes in the heat-conducting medium within the first groove of the test tube 61. The density of mercury is expressed as approximately 13.6. 10 3 kg / m 3 ), Expressed as gravitational acceleration, It is represented as the height difference between the initial height h0 and the measured height h.

[0110] After the test, turn off the power to the test device, and after the frame 4 of the test device returns to normal temperature, drain the heat-conducting medium, take out the test tube 61 from the first groove and remove the test sample from the test tube 61.

[0111] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this application can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0112] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this application. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this application, and the shapes and sizes of the components in the drawings do not reflect actual size and proportion, but only illustrate the content of the embodiments of this application.

[0113] Unless otherwise stated, the numerical parameters in this specification and the appended claims are approximate values ​​and can be varied according to desired characteristics derived from the content of this application. Specifically, all figures used in the specification and claims to indicate composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Generally, this means that a specific amount may vary by ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments.

[0114] The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify the corresponding elements does not imply that the element has any ordinal number, nor does it represent the order of one element with another element, or the order of manufacturing methods. The use of these ordinal numbers is only to enable a named element to be clearly distinguished from another element with the same name.

[0115] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0116] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this application is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this application, and all such substitutions and modifications should fall within the scope of this application.

Claims

1. A testing device for the separation pressure of pore solution in concrete under freezing conditions, characterized in that, include: The frame has a first groove in the middle, and two second grooves are opened at intervals on both sides of the first groove. The bottom of the two second grooves are connected to the first groove. The first groove and the two second grooves are filled with a heat-conducting medium. Two sets of bipolar semiconductors are respectively disposed in two second grooves. The opposite sides of each set of bipolar semiconductors are configured to form a cold surface and a hot surface respectively in response to the excitation of an external DC current. The cold surface is in contact with the side of the second groove near the first groove to exchange heat with the heat-conducting medium in the first groove. The testing mechanism is located within the first groove and is configured to obtain the separation pressure by measuring the height change caused by the separation pressure generated when the test sample, based on a mercury-based concrete pore solution, freezes in the thermally conductive medium within the first groove.

2. The testing apparatus according to claim 1, characterized in that, The testing facility includes: A test tube, wherein the test sample is filled inside the test tube; Pressure testing tube, including: The connecting part, one end of which is connected to the test tube; The U-shaped section has an open end and a closed end, the open end being connected to the other end of the connecting part, and the U-shaped section is filled with mercury to respond to a significant change in separation pressure caused by the freezing of the test sample in the thermally conductive medium within the first groove.

3. The testing apparatus according to claim 2, characterized in that, The side wall of the frame is provided with a U-shaped groove to accommodate the U-shaped part, thereby facilitating external observation of the mercury height change.

4. The testing apparatus according to claim 2, characterized in that, The testing facility also includes: A reference plate is disposed on one side of the test tube, and a scale is provided on the side of the reference plate facing the test tube. A support is disposed on the side of the test tube opposite to the reference plate; A reflector is mounted on the bracket to allow observation of the thickness of the unfrozen layer of the test sample during the freezing process from above the bracket.

5. The testing apparatus according to claim 4, characterized in that, Also includes: A cover is disposed above the frame, and the cover has a window facing the first groove to facilitate observation of the thickness of the unfrozen layer through the reflector and the ruler; A glass plate is installed in the window to maintain the temperature within the first recess.

6. The testing apparatus according to claim 5, characterized in that, Also includes: A housing having an accommodating space to accommodate the frame and the cover.

7. The testing apparatus according to claim 1, characterized in that, Also includes: Two first fans are respectively disposed at the bottom of the two second grooves, so that the heat-conducting medium in the two second grooves can exchange heat with the heat-conducting medium in the first groove.

8. The testing apparatus according to claim 1, characterized in that, The housing has two openings on each of its two sidewalls facing the hot surfaces of the two sets of bipolar semiconductors. The testing device also includes: Two second fans are respectively installed in the two openings to dissipate heat from the hot surfaces of the two sets of bipolar semiconductors.

9. The testing apparatus according to claim 1, characterized in that, Also includes: At least one temperature sensor is disposed on the sidewall of the first groove to detect the temperature inside the first groove.

10. A method for testing the separation pressure of concrete pore solution under freezing conditions, applicable to the testing apparatus for testing the separation pressure of concrete pore solution under freezing conditions as described in any one of claims 1-9, characterized in that, The testing method includes: The test sample is injected into the test tube with concrete pore solution, and the test tube filled with the test sample is installed in the first groove of the frame. Connect the pressure testing tube to the top of the test tube; Inject heat-conducting medium into the first groove and two second grooves of the frame, and then cover the top of the frame with the cover; When the test tube is at room temperature and pressure, record the initial height of the mercury column in the U-shaped part of the pressure measuring tube; Turn on two first fans and two second fans, and adjust the magnitude of the DC current applied to the bipolar semiconductor so that the temperature of the heat-conducting medium in the first groove reaches the target temperature. The thickness of the unfrozen layer of the test sample during the freezing process was observed using a reflector, and the measured height of the mercury column in the U-shaped section was recorded. Based on the initial height and the measured height, the separation pressure generated when the test sample freezes in the thermally conductive medium within the first groove is obtained.

Images