Apparatus and methods for testing the strength of concrete specimens before and after freezing.

Abstract

This invention relates to the field of concrete strength testing technology, and in particular to a device and method for testing the strength of concrete specimens before and after freezing. It includes two pressure plate assemblies, with frozen concrete placed between the base and the lower pressure plate assembly, and room-temperature concrete placed between the lower and upper pressure plate assemblies. A hydraulic cylinder's movable end is fixedly connected to the top of the upper pressure plate assembly for outputting pressure. Both frozen and room-temperature concrete are subjected to pressure simultaneously. This invention significantly increases the testing efficiency of concrete specimen strength, nearly doubling the efficiency. It avoids, to some extent, the problems of long sample waiting times or excessive freezing time, which can easily lead to sample discrepancies. Through clever design, a single press can simultaneously test two samples, overcoming the difficulties of inconsistent destruction thresholds and elastic moduli when testing multiple concrete specimens simultaneously, which can easily cause mutual interference in test results, and the easy release of internal stress in concrete specimens due to force release.

Description

Technical Field

[0001] This invention relates to the field of concrete strength testing technology, specifically to a device and method for testing the strength of concrete specimens before and after freezing. Background Technology

[0002] Strength and dynamic modulus of elasticity are the most important mechanical properties of concrete, which are directly related to the safety and durability of engineering projects.

[0003] Currently, the method for testing the strength of concrete specimens is to gradually apply pressure to the concrete specimen, and the pressure cannot be removed during the application process until the concrete specimen is destroyed. The strength of the concrete specimen is obtained by measuring the ratio of the pressure on the specimen to the area of ​​force application when the specimen is destroyed.

[0004] To ensure the accuracy of the test, multiple (dozens) concrete specimens need to be tested, and the average value is taken after removing extreme values.

[0005] In high-altitude areas, it is also necessary to test the strength of concrete after freezing, which greatly increases the number of samples. The efficiency of strength testing for large numbers of samples in the existing technology needs to be improved, and there is a problem of excessively long sample waiting time, which can easily cause sample differences.

[0006] When concrete freezes, the formation of ice increases the elastic modulus and strength of the concrete. Once the weather warms up, the concrete strength will return to its true value.

[0007] This invention, through its ingenious design, enables a single press to simultaneously test two samples, overcoming the difficulties that arise when multiple concrete specimens are tested simultaneously, such as inconsistent failure thresholds and elastic moduli that can easily lead to mutual interference in test results, and the ease with which internal stress in concrete specimens can be released due to force release.

[0008] Therefore, a device and method for testing the strength of concrete specimens before and after freezing are proposed to address the above problems. Summary of the Invention

[0009] The purpose of this invention is to provide a device and method for testing the strength of concrete specimens before and after freezing, which enables a single press to test two samples simultaneously. This overcomes the problems that when multiple concrete specimens are tested simultaneously, the inconsistent failure threshold and elastic modulus can easily cause the test results to affect each other, and the internal stress of the concrete specimens can easily be released due to the release of force.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a strength testing device for concrete specimens before and after freezing, comprising a base, a hydraulic cylinder fixedly connected to the base via a gantry frame, and two pressure plate assemblies, wherein frozen concrete is placed between the base and the lower pressure plate assembly, and room temperature concrete is placed between the lower pressure plate assembly and the upper pressure plate assembly, and the movable end of the hydraulic cylinder is fixedly connected to the top of the upper pressure plate assembly for outputting pressure, wherein frozen concrete and room temperature concrete simultaneously bear pressure;

[0011] During the pressurization process, the room temperature concrete breaks first due to its lower strength. At this time, the anti-reverse component locks the lower pressure plate component to prevent the release of internal stress in the frozen concrete. As the moving end of the hydraulic cylinder moves downward, the bearing rod fixedly connected to the bottom of the upper pressure plate component contacts the lower pressure plate component and continues to apply pressure to continue testing the strength of the frozen concrete.

[0012] Preferably, in the strength testing device for concrete specimens before and after freezing according to the present invention, the height of the bearing rod is lower than the height of the concrete specimen being tested.

[0013] Preferably, as a strength testing device for concrete specimens before and after freezing according to the present invention, each pressure plate assembly includes an upper support plate on the upper side and a lower pressure plate on the lower side, and a force sensor is fixedly connected between the upper support plate and the lower pressure plate to obtain the applied pressure of the corresponding concrete specimen.

[0014] In this invention, the frozen concrete is artificially manufactured and taken out from the frozen environment during testing. This invention can greatly increase the testing efficiency of concrete specimen strength by nearly doubling the efficiency. To a certain extent, it avoids the problems of sample waiting or excessive freezing time, which can easily cause sample differences. Through ingenious design, this invention enables a single press to test two samples simultaneously, overcoming the difficulties that when multiple concrete specimens are tested at the same time, such as inconsistent destruction thresholds and elastic moduli that can easily cause mutual influence of test results, and the difficulty that the internal stress of concrete specimens can be easily released due to force release.

[0015] When using it, first place the frozen concrete between the base and the lower pressure plate assembly, and place the normal temperature concrete between the lower pressure plate assembly and the upper pressure plate assembly; then, by adjusting the moving end of the hydraulic cylinder and the suspended lower pressure plate assembly, align the bottom end of the upper lower pressure plate with the upper surface of the normal temperature concrete, and align the bottom end of the lower lower pressure plate with the upper surface of the frozen concrete.

[0016] Secondly, the moving end of the hydraulic cylinder outputs pressure. During the pressurization process, the room temperature concrete breaks first due to its low strength. The anti-reverse component locks the lower pressure plate component to prevent the release of internal stress in the frozen concrete. The force sensor in the upper pressure plate component obtains the applied pressure before the room temperature concrete breaks in real time during the pressurization process. The highest pressure value is the breaking pressure of the room temperature concrete, thereby obtaining the strength of the room temperature concrete. In order to reduce the impact of fragment separation after the room temperature concrete breaks on the measurement, a shielding net can be set on the upper outer side of the lower pressure plate component.

[0017] Preferably, as a strength testing device for concrete specimens before and after freezing according to the present invention, a second limiting rod is fixedly connected to the top of the base, and connectors are fixedly connected to both ends of the upper bearing plate in the lower pressure plate assembly. The connectors are distributed diagonally on the upper bearing plate, and the connectors are slidably connected to the outer side of the second limiting rod. After the room temperature concrete is placed on the lower pressure plate assembly, the lower pressure plate assembly can be suspended by the second limiting rod and the damper.

[0018] Preferably, as a strength testing device for concrete specimens before and after freezing according to the present invention, a damper is fixedly connected to the inner side of one end of the connector. The damper applies frictional force to the second limiting rod to counteract the gravity of the lower pressure plate assembly and the normal temperature concrete, so that the compressive strength of the normal temperature concrete and the frozen concrete is consistent.

[0019] The damper is existing technology and will not be elaborated on here. Its general internal principle is that the damping force can be adjusted by the spring pushing the pressure plate onto the second limit rod and by adjusting the compression of the spring.

[0020] Preferably, the damper used in this invention for testing the strength of concrete specimens before and after freezing is a variable damper, which allows the damping to be adjusted to suit concrete specimens of different weights.

[0021] In the above configuration, in order to ensure that the compressive strength of the room temperature concrete and the frozen concrete is consistent when the hydraulic cylinder is working, the present invention sets a second limiting rod and a damper to suspend the lower pressure plate assembly. The damper applies frictional force to the second limiting rod to counteract the gravity of the lower pressure plate assembly and the room temperature concrete, thereby preventing the gravity of the room temperature concrete and the lower pressure plate assembly from being superimposed on the frozen concrete. This ensures that under the same hydraulic cylinder pressure, the compressive strength of the room temperature concrete and the frozen concrete is consistent, and the room temperature concrete, due to its slightly lower strength, can break first.

[0022] Preferably, in the strength testing device for concrete specimens before and after freezing of the present invention, the upper bearing plate of the lower pressure plate assembly is fixedly connected to both the left and right ends of the upper bearing plate. The check pieces are distributed diagonally on the upper bearing plate. The anti-reverse assembly includes a drive member that rotates inside the base and a first limiting rod fixed on the base. The drive member can rotate. A lead screw is fixedly connected to the top of the drive member. A top plate is rotatably connected to the top of the lead screw. The bottom end of the top plate is fixedly connected to the top of the first limiting rod. A pressure block is spirally connected to the outside of the lead screw. The inside of the pressure block is slidably connected to the outside of the first limiting rod. The pressure block can move downward with the check piece to lock the lower pressure plate assembly.

[0023] In this invention, the upward reset of the pressure block is achieved by the reverse rotation of the motor; after the room temperature concrete is broken, the upper pressure plate assembly and the lower pressure plate assembly lose their rigid connection, and the anti-reverse assembly is used to lock the internal stress inside the frozen concrete after the room temperature concrete is broken, to prevent the release of the internal stress inside the frozen concrete, and to ensure that the testing continues.

[0024] Preferably, in the strength testing device for concrete specimens before and after freezing of the present invention, the driving component is a motor, and a push switch is fixedly connected to the inner side of the pressure block. When the check piece is detached from the pressure block, the push switch is released, the motor can rotate, the motor drives the lead screw to rotate, and the rotation of the lead screw forces the pressure block to move downward to follow the check piece. When the check piece is completely close to the pressure block, the push switch is pressed, the motor can stop, so that the check piece and the pressure block remain close.

[0025] Under the above settings, the following movement of the pressure block is controlled by a push switch to ensure that the pressure block follows the movement of the check valve.

[0026] Preferably, in the present invention, a motor is fixedly connected to the inner side of the base for testing the strength of concrete specimens before and after freezing. A coupling component is fixedly connected to the output end of the motor. The coupling component and the inner side of the drive component are driven by magnetic coupling. The motor keeps rotating, the lead screw rotates and drives the pressure block to follow the movement of the check component. After the pressure block and the check component are pressed together, the resistance of the pressure block increases and the coupling component rotates independently. When the coupling component rotates independently, in order to avoid the pressure block from generating a large downward pressure on the check component, the coupling strength is preset to ensure that the downward pressure generated by the pressure block on the check component is low and can be ignored.

[0027] The coupling element is rotatably connected to the driving element, and the coupling between the coupling element and the inner side of the driving element can also be achieved through friction of the friction pads;

[0028] As the moving end of the hydraulic cylinder descends, the pressure-bearing rod fixedly connected to the bottom of the upper pressure plate assembly contacts the lower pressure plate assembly and continues to apply pressure, thus continuing to test the strength of the frozen concrete. The force sensor in the lower pressure plate assembly obtains the applied pressure before the frozen concrete breaks during the pressure application process in real time. The highest value of the pressure is the breaking pressure of the frozen concrete, thereby obtaining the strength of the frozen concrete.

[0029] The potentiometer surface is slidably connected to the slider fixedly connected inside the connector. When the pressure plate assembly on the lower side moves downward, the potentiometer surface and the slider are displaced. The potentiometer and the slider fixedly connected inside the connector can obtain the deformation distance of the frozen concrete until it breaks. Combined with the compressive strength at the time of breakage, the elastic modulus of the frozen concrete can be obtained.

[0030] The deformation distance of room-temperature concrete until it breaks is equal to the extension distance of the hydraulic cylinder when the room-temperature concrete breaks minus the deformation distance of the frozen concrete. Combined with the compressive strength at the time of breakage, the elastic modulus of room-temperature concrete can be obtained.

[0031] The method for testing the strength of concrete specimens before and after freezing involves the following steps:

[0032] Step 1: Place the frozen concrete between the base and the lower pressure plate assembly, and place the normal temperature concrete between the lower pressure plate assembly and the upper pressure plate assembly.

[0033] Step 2: Adjust the gap. By adjusting the moving end of the hydraulic cylinder and the lower pressure plate assembly in the suspended state, align the bottom end of the upper pressure plate with the upper surface of the normal temperature concrete and the bottom end of the lower pressure plate with the upper surface of the frozen concrete.

[0034] Step 3: The moving end of the hydraulic cylinder outputs pressure. During the pressurization process, the room temperature concrete breaks first due to its lower strength. The anti-reverse component locks the lower pressure plate component to prevent the release of internal stress in the frozen concrete. The force sensor in the upper pressure plate component obtains the applied pressure before the room temperature concrete breaks in real time during the pressurization process. The highest pressure value is the breaking pressure of the room temperature concrete, thereby obtaining the strength of the room temperature concrete.

[0035] Step 4: As the moving end of the hydraulic cylinder descends, the pressure rod fixedly connected to the bottom of the upper pressure plate assembly contacts the lower pressure plate assembly and continues to apply pressure, continuing to test the strength of the frozen concrete. The force sensor in the lower pressure plate assembly obtains the applied pressure of the frozen concrete before it breaks in real time during the pressure application process. The highest pressure value is the breaking pressure of the frozen concrete, thereby obtaining the strength of the frozen concrete.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. The present invention provides a device for testing the strength of concrete specimens before and after freezing. This invention can greatly increase the testing efficiency of concrete specimens by nearly doubling the efficiency. To a certain extent, it avoids the problem of excessively long sample waiting or freezing time, which can easily cause sample differences. Through ingenious design, the present invention enables a single press to test two samples simultaneously, overcoming the difficulties that when multiple concrete specimens are tested at the same time, the inconsistent destruction threshold and elastic modulus can easily cause the test results to affect each other, and the internal stress of the concrete specimens can easily be released due to the release of force.

[0038] 2. In order to ensure that the compressive strength of the concrete specimens before and after freezing is consistent when the hydraulic cylinder is working, this invention sets a second limiting rod and a damper to suspend the lower pressure plate assembly. The damper applies frictional force to the second limiting rod to counteract the weight of the lower pressure plate assembly and the normal temperature concrete, thus preventing the weight of the normal temperature concrete and the lower pressure plate assembly from being superimposed on the frozen concrete. This ensures that under the same hydraulic cylinder pressure, the compressive strength of the normal temperature concrete and the frozen concrete is consistent, and the normal temperature concrete, due to its slightly lower strength, can break first.

[0039] 3. The strength testing device for concrete specimens before and after freezing: After the concrete at room temperature breaks, the upper pressure plate assembly and the lower pressure plate assembly lose their rigid connection. The anti-reverse assembly is used to lock the internal stress inside the frozen concrete after the concrete at room temperature breaks, to prevent the release of the internal stress inside the frozen concrete, and to ensure that the testing continues.

[0040] 4. The strength testing device for concrete specimens before and after freezing involves a potentiometer surface and a slider fixedly connected to the connector. When the lower pressure plate assembly moves downward, the potentiometer surface and the slider are displaced. The potentiometer and the slider fixedly connected to the connector can obtain the deformation distance of the frozen concrete until it breaks. Combined with the compressive strength at the time of breakage, the elastic modulus of the frozen concrete can be obtained. The deformation distance of the normal temperature concrete until it breaks is equal to the extension distance of the hydraulic cylinder at the time of breakage minus the deformation distance of the frozen concrete. Combined with the compressive strength at the time of breakage, the elastic modulus of the normal temperature concrete can be obtained. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the overall appearance and structure of the present invention;

[0042] Figure 2 This is a schematic diagram of a partial explosion structure of the present invention;

[0043] Figure 3 This is a front view of the installation structure of the two pressure plate assemblies in Embodiment 1 of the present invention;

[0044] Figure 4 For the present invention Figure 3Enlarged structural diagram at point A in the diagram;

[0045] Figure 5 This is a front view of the installation structure at the two pressure plate assemblies in Embodiment 2 of the present invention;

[0046] Figure 6 For the present invention Figure 5 Enlarged structural diagram at point B in the diagram;

[0047] Figure 7 This is a schematic diagram of step one in the strength testing process of the present invention;

[0048] Figure 8 This is a schematic diagram of step two in the strength testing process of the present invention;

[0049] Figure 9 This is a schematic diagram of step three in the strength testing process of the present invention;

[0050] Figure 10 This is a schematic diagram of step four in the strength testing process of the present invention;

[0051] Figure 11 This is a schematic diagram of the mounting structure at the potentiometer of the present invention.

[0052] In the diagram: 1. Base; 2. Gantry frame; 3. Hydraulic cylinder; 4. Pressure plate assembly; 5. Connector; 6. Damper; 7. Check valve; 8. First limit rod; 9. Drive unit; 10. Pressure rod; 11. Lead screw; 12. Second limit rod; 13. Top plate; 14. Pressure block; 15. Push switch; 16. Motor; 17. Coupling component; 18. Potentiometer; 19. Slider;

[0053] 41. Upper support plate; 42. Lower pressure plate; 43. Force sensor. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Example 1, please refer to Figures 1-4 , Figures 7-10 The present invention provides a technical solution:

[0056] The device for testing the strength of concrete specimens before and after freezing includes a base 1, a hydraulic cylinder 3 fixedly connected to the base 1 via a gantry frame 2, and two pressure plate assemblies 4. Frozen concrete b is placed between the base 1 and the lower pressure plate assembly 4, and room temperature concrete a is placed between the lower pressure plate assembly 4 and the upper pressure plate assembly 4. The movable end of the hydraulic cylinder 3 is fixedly connected to the top of the upper pressure plate assembly 4 for outputting pressure. Frozen concrete b and room temperature concrete a simultaneously bear pressure.

[0057] During the pressure application process, the room temperature concrete a breaks first due to its lower strength. At this time, the anti-reverse component locks the lower pressure plate component 4 to prevent the release of internal stress in the frozen concrete b. As the moving end of the hydraulic cylinder 3 moves downward, the bearing rod 10 fixedly connected to the bottom end of the upper pressure plate component 4 contacts the lower pressure plate component 4 and continues to apply pressure to continue testing the strength of the frozen concrete b.

[0058] Preferably, in the strength testing device for concrete specimens before and after freezing, the height of the bearing rod 10 is lower than the height of the concrete specimen being tested.

[0059] Preferably, as a strength testing device for concrete specimens before and after freezing, each pressure plate assembly 4 includes an upper support plate 41 on the upper side and a lower pressure plate 42 on the lower side, with a force sensor 43 fixedly connected between the upper support plate 41 and the lower pressure plate 42 to obtain the applied pressure of the corresponding concrete specimen.

[0060] In this invention, the frozen concrete b is artificially manufactured and taken out from the frozen environment during testing. This invention can greatly increase the testing efficiency of concrete specimen strength by nearly doubling the efficiency. To a certain extent, it avoids the problems of sample waiting or excessive freezing time, which can easily cause sample differences. Through ingenious design, this invention enables a single press to test two samples simultaneously, overcoming the difficulties that when multiple concrete specimens are tested at the same time, such as inconsistent destruction thresholds and elastic moduli that can easily cause mutual influence of test results, and the difficulty that the internal stress of concrete specimens can be easily released due to force release.

[0061] In use, first place the frozen concrete b between the base 1 and the lower pressure plate assembly 4, and place the normal temperature concrete a between the lower pressure plate assembly 4 and the upper pressure plate assembly 4; then, by adjusting the movable end of the hydraulic cylinder 3 and the suspended lower pressure plate assembly 4, align the bottom end of the upper lower pressure plate 42 with the upper surface of the normal temperature concrete a, and align the bottom end of the lower lower pressure plate 42 with the upper surface of the frozen concrete b.

[0062] Secondly, the moving end of the hydraulic cylinder 3 outputs pressure. During the pressurization process, the room temperature concrete a breaks first due to its low strength. The anti-reverse component locks the lower pressure plate component 4 to prevent the release of internal stress in the frozen concrete b. The force sensor 43 in the upper pressure plate component 4 obtains the applied pressure of the room temperature concrete a before it breaks in real time during the pressurization process. The highest value of the pressure is the breaking pressure of the room temperature concrete a, thereby obtaining the strength of the room temperature concrete a. In order to reduce the impact of fragment separation on the measurement after the room temperature concrete a breaks, a shielding net can be set on the upper outer side of the lower pressure plate component 4.

[0063] Preferably, as a strength testing device for concrete specimens before and after freezing according to the present invention, the top of the base 1 is fixedly connected to a second limiting rod 12, and the upper support plate 41 in the lower pressure plate assembly 4 is fixedly connected to both the left and right ends of the upper support plate 41. The connecting parts 5 are distributed diagonally on the upper support plate 41, and the connecting parts 5 are slidably connected to the outer side of the second limiting rod 12. After the room temperature concrete a is placed on the lower pressure plate assembly 4, the lower pressure plate assembly 4 can be suspended by the second limiting rod 12 and the damper 6.

[0064] Preferably, as a strength testing device for concrete specimens before and after freezing, the inner side of one end of the connector 5 is fixedly connected to a damper 6. The damper 6 applies frictional force to the second limiting rod 12 to counteract the gravity of the lower pressure plate assembly 4 and the normal temperature concrete a, so that the compressive strength of the normal temperature concrete a and the frozen concrete b is consistent.

[0065] The damper is existing technology and will not be elaborated on here. Its general internal principle is that the spring pushes the pressure plate to act on the second limit rod 12, and the damping force is adjusted by adjusting the compression of the spring.

[0066] Preferably, as the strength testing device for concrete specimens before and after freezing in this invention, the damper 6 is a variable damper, so that the damping of the damper 6 can be adjusted to suit concrete specimens of different weights.

[0067] In the above configuration, in order to ensure that the compressive strength of the room temperature concrete a and the frozen concrete b is consistent when the hydraulic cylinder 3 is working, the present invention sets a second limiting rod 12 and a damper 6 to suspend the lower pressure plate assembly 4. The damper 6 applies frictional force to the second limiting rod 12 to counteract the gravity of the lower pressure plate assembly 4 and the room temperature concrete a, so as to prevent the gravity of the room temperature concrete a and the lower pressure plate assembly 4 from being superimposed on the frozen concrete b, and to ensure that the compressive strength of the room temperature concrete a and the frozen concrete b is consistent under the same pressure of the hydraulic cylinder 3. The room temperature concrete a, because of its slightly lower strength, can break first.

[0068] Preferably, in the strength testing device for concrete specimens before and after freezing of the present invention, the upper support plate 41 of the lower pressure plate assembly 4 is fixedly connected to both the left and right ends of the upper support plate 41. The check pieces 7 are distributed diagonally on the upper support plate 41. The anti-reverse assembly includes a drive piece 9 that rotates inside the base 1 and a first limiting rod 8 fixed on the base 1. The drive piece 9 can rotate. A lead screw 11 is fixedly connected to the top of the drive piece 9. A top plate 13 is rotatably connected to the top of the lead screw 11. The bottom end of the top plate 13 is fixedly connected to the top end of the first limiting rod 8. A pressure block 14 is spirally connected to the outside of the lead screw 11. The inside of the pressure block 14 is slidably connected to the outside of the first limiting rod 8. The pressure block 14 can move downward with the check piece 7 to lock the lower pressure plate assembly 4.

[0069] In this invention, the upward reset of the pressure block 14 is achieved by the reverse rotation of the motor; after the room temperature concrete a is broken, the upper pressure plate assembly 4 and the lower pressure plate assembly 4 lose their hard connection. The anti-reverse assembly is used to lock the internal stress inside the frozen concrete b after the room temperature concrete a is broken, to prevent the release of the internal stress inside the frozen concrete b, and to ensure that the test continues.

[0070] Preferably, in the strength testing device for concrete specimens before and after freezing of the present invention, the driving component 9 is a motor, and a push switch 15 is fixedly connected to the inner side of the pressure block 14. When the check piece 7 is detached from the pressure block 14, the push switch 15 is released, the motor can rotate, the motor drives the lead screw 11 to rotate, and the rotation of the lead screw 11 forces the pressure block 14 to move downward to follow the check piece 7. When the check piece 7 and the pressure block 14 are completely close, the push switch 15 is pressed, the motor can stop, so that the check piece 7 and the pressure block 14 remain close.

[0071] Under the above settings, the following movement of the pressure block 14 is controlled by the push switch 15 to ensure that the pressure block 14 follows the movement of the check valve 7;

[0072] As the movable end of the hydraulic cylinder 3 moves downward, the pressure rod 10 fixedly connected to the bottom of the upper pressure plate assembly 4 contacts the lower pressure plate assembly 4 and continues to apply pressure, continuing to test the strength of the frozen concrete b. The force sensor 43 in the lower pressure plate assembly 4 obtains the applied pressure of the frozen concrete b before it breaks during the pressure application process in real time. The highest value of the pressure is the breaking pressure of the frozen concrete b, thereby obtaining the strength of the frozen concrete b.

[0073] Example 2 is another embodiment of Example 1. The identical parts will not be repeated here; please refer to [link / reference]. Figures 1-2 , Figures 5-10A motor 16 is fixedly connected to the inner side of the base 1. A coupling member 17 is fixedly connected to the output end of the motor 16. The coupling member 17 is magnetically coupled to the inner side of the drive member 9. The motor 16 keeps rotating, and the lead screw 11 rotates and drives the pressure block 14 to follow the movement of the check piece 7. After the pressure block 14 is pressed against the check piece 7, the resistance of the pressure block 14 increases, and the coupling member 17 rotates independently. When the coupling member 17 rotates independently, in order to avoid the pressure block 14 from generating a large downward pressure on the check piece 7, the power is cut off in time as the resistance of the pressure block 14 increases after it is pressed against the check piece 7 by setting the coupling strength. This ensures that the downward pressure generated by the pressure block 14 on the check piece 7 is low and can be ignored.

[0074] The coupling element 17 is rotatably connected to the driving element 9, and the coupling between the coupling element 17 and the inner side of the driving element 9 can also be achieved by friction of the friction plate.

[0075] Example 3 is a supplement to Examples 1 and 2. The same parts will not be described again. The surface of potentiometer 18 is slidably connected to the slider 19 fixedly connected inside the connector 5. When the pressure plate assembly 4 on the lower side moves down, the surface of potentiometer 18 and slider 19 are displaced. Potentiometer 18 and slider 19 fixedly connected inside the connector 5 can obtain the deformation distance of frozen concrete b until it breaks. Combined with the compressive strength at the time of breakage, the elastic modulus of frozen concrete b can be obtained.

[0076] The deformation distance of the room-temperature concrete b until it breaks is equal to the extension distance of the hydraulic cylinder 3 when the room-temperature concrete b breaks minus the deformation distance of the frozen concrete a. Combined with the compressive strength at the time of breakage, the elastic modulus of the room-temperature concrete a can be obtained.

[0077] This invention also discloses a method for testing the strength of concrete specimens before and after freezing, the steps of which are as follows:

[0078] Step 1: Place the frozen concrete b between the base 1 and the lower pressure plate assembly 4, and place the normal temperature concrete a between the lower pressure plate assembly 4 and the upper pressure plate assembly 4.

[0079] Step 2: Adjust the gap. By adjusting the movable end of the hydraulic cylinder 3 and the suspended lower pressure plate assembly 4, align the bottom end of the upper lower pressure plate 42 with the upper surface of the normal temperature concrete a, and align the bottom end of the lower lower pressure plate 42 with the upper surface of the frozen concrete b.

[0080] Step 3: The moving end of the hydraulic cylinder 3 outputs pressure. During the pressurization process, the room temperature concrete a breaks first due to its low strength. The anti-reverse component locks the lower pressure plate component 4 to prevent the release of internal stress in the frozen concrete b. The force sensor 43 in the upper pressure plate component 4 obtains the applied pressure of the room temperature concrete a before it breaks in real time during the pressurization process. The highest pressure value is the breaking pressure of the room temperature concrete a, thereby obtaining the strength of the room temperature concrete a.

[0081] Step 4: As the movable end of the hydraulic cylinder 3 descends, the pressure rod 10 fixedly connected to the bottom of the upper pressure plate assembly 4 contacts the lower pressure plate assembly 4 and continues to apply pressure, continuing to test the strength of the frozen concrete b. The force sensor 43 in the lower pressure plate assembly 4 obtains the applied pressure of the frozen concrete b before it breaks in real time during the pressure application process. The highest value of the pressure is the breaking pressure of the frozen concrete b, thereby obtaining the strength of the frozen concrete b.

[0082] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for testing the strength of concrete specimens before and after freezing, comprising a base (1) and a hydraulic cylinder (3) fixedly connected to the base (1) via a gantry frame (2), characterized in that: It also includes two pressure plate assemblies (4), with frozen concrete (b) placed between the base (1) and the lower pressure plate assembly (4), and normal temperature concrete (a) placed between the lower pressure plate assembly (4) and the upper pressure plate assembly (4). The movable end of the hydraulic cylinder (3) is fixedly connected to the top of the upper pressure plate assembly (4) for outputting pressure, and frozen concrete (b) and normal temperature concrete (a) bear pressure at the same time. During the pressure application process, the normal temperature concrete (a) breaks first due to its low strength. At this time, the anti-reverse component locks the lower pressure plate component (4) to prevent the release of internal stress in the frozen concrete (b). As the moving end of the hydraulic cylinder (3) moves down, the bearing rod (10) fixedly connected to the bottom of the upper pressure plate component (4) contacts the lower pressure plate component (4) and continues to apply pressure to continue testing the strength of the frozen concrete (b). The height of the bearing rod (10) is lower than the height of the concrete specimen being tested. Each pressure plate component (4) includes an upper bearing plate (41) on the upper side and a lower pressure plate (42) on the lower side. A force sensor (43) is fixedly connected between the upper bearing plate (41) and the lower pressure plate (42) to obtain the applied pressure of the corresponding concrete specimen. The top of the base (1) is fixedly connected to a second limiting rod (12). The upper support plate (41) in the lower pressure plate assembly (4) is fixedly connected to both the left and right ends of the upper support plate (41). The connecting parts (5) are distributed diagonally on the upper support plate (41). The connecting parts (5) are slidably connected to the outer side of the second limiting rod (12). After the room temperature concrete (a) is placed on the lower pressure plate assembly (4), the lower pressure plate assembly (4) can be suspended by the second limiting rod (12) and the damper (6). The upper support plate (41) of the lower pressure plate assembly (4) is fixedly connected to both ends of the upper support plate (41). The anti-reverse components (7) are distributed diagonally on the upper support plate (41). The anti-reverse assembly includes a drive component (9) that rotates inside the base (1) and a first limiting rod (8) fixed on the base (1). The drive component (9) can rotate. The top end of the drive component (9) is fixedly connected to a lead screw (11). The top end of the lead screw (11) is rotatably connected to a top plate (13). The bottom end of the top plate (13) is fixedly connected to the top end of the first limiting rod (8). The outer side of the lead screw (11) is spirally connected to a pressure block (14). The inner side of the pressure block (14) is slidably connected to the outer side of the first limiting rod (8). The pressure block (14) can move downward with the anti-reverse component (7) to lock the lower pressure plate assembly (4).

2. The device for testing the strength of concrete specimens before and after freezing according to claim 1, characterized in that: A damper (6) is fixedly connected to the inner side of one end of the connector (5). The damper (6) applies frictional force to the second limiting rod (12) to counteract the gravity of the lower pressure plate assembly (4) and the normal temperature concrete (a), so that the compressive strength of the normal temperature concrete (a) and the frozen concrete (b) is consistent.

3. The strength testing device for concrete specimens before and after freezing according to claim 2, characterized in that: The damper (6) is a variable damper, which allows the damping of the damper (6) to be adjusted to suit concrete specimens of different weights.

4. The device for testing the strength of concrete specimens before and after freezing according to claim 1, characterized in that: The driving component (9) is a motor. A push switch (15) is fixedly connected to the inner side of the pressure block (14). When the check piece (7) is detached from the pressure block (14), the push switch (15) is released, the motor can rotate, and the pressure block (14) moves with the check piece (7). When the check piece (7) and the pressure block (14) are completely close, the push switch (15) is pressed, and the motor can stop.

5. The device for testing the strength of concrete specimens before and after freezing according to claim 4, characterized in that: A motor (16) is fixedly connected to the inner side of the base (1), and a coupling element (17) is fixedly connected to the output end of the motor (16). The coupling element (17) and the inner side of the drive element (9) are driven by magnetic coupling. After the pressure block (14) moves downward following the check element (7) and is pressed against the check element (7), the resistance of the pressure block (14) increases, and the coupling element (17) rotates independently.

6. A method for testing the strength of concrete specimens before and after freezing, using the strength testing device for concrete specimens before and after freezing as described in claim 5, characterized in that, The steps are as follows: Step 1: Place frozen concrete (b) between the base (1) and the lower pressure plate assembly (4), and place normal temperature concrete (a) between the lower pressure plate assembly (4) and the upper pressure plate assembly (4). Step 2: Adjust the gap. By adjusting the movable end of the hydraulic cylinder (3) and the suspended lower pressure plate assembly (4), the bottom end of the upper lower pressure plate (42) is aligned with the upper surface of the normal temperature concrete (a), and the bottom end of the lower pressure plate (42) is aligned with the upper surface of the frozen concrete (b). Step 3: The moving end of the hydraulic cylinder (3) outputs pressure. During the pressurization process, the room temperature concrete (a) breaks first due to its low strength. The anti-reverse component locks the lower pressure plate component (4) to prevent the release of internal stress in the frozen concrete (b). The force sensor (43) in the upper pressure plate component (4) obtains the applied pressure of the room temperature concrete (a) before it breaks during the pressurization process in real time. The highest value of the pressure is the breaking pressure of the room temperature concrete (a), thereby obtaining the strength of the room temperature concrete (a). Step 4: As the moving end of the hydraulic cylinder (3) moves downward, the pressure rod (10) fixedly connected to the bottom end of the upper pressure plate assembly (4) contacts the lower pressure plate assembly (4) and continues to apply pressure, continuing to test the strength of the frozen concrete (b). The force sensor (43) in the lower pressure plate assembly (4) obtains the pressure applied to the frozen concrete (b) before it breaks during the pressure application process in real time. The highest value of the pressure is the breaking pressure of the frozen concrete (b), thereby obtaining the strength of the frozen concrete (b).

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