Device and method for detecting strength of concrete test piece before and after freezing

Abstract

The invention relates to the technical field of concrete strength detection, in particular to a device and method for detecting the strength of a concrete test piece before and after freezing, the device comprises an upper pressing plate assembly and a lower pressing plate assembly, frozen concrete is placed between a base and the pressing plate assembly on the lower side, and normal-temperature concrete is placed between the pressing plate assembly on the lower side and the pressing plate assembly on the upper side; the movable end of the hydraulic cylinder is fixedly connected with the top end of the pressing plate assembly on the upper side and used for outputting pressure, frozen concrete and normal-temperature concrete bear the pressure at the same time, the detection efficiency of the strength of the concrete test piece can be greatly improved, the efficiency is improved by nearly one time, and the problem that the sample waiting or freezing time is too long is solved to a certain extent; through ingenious design, a single press machine can detect two samples at the same time, and the difficulties that when multiple concrete test pieces are detected at the same time, detection results are prone to mutual influence due to inconsistent damaged threshold values and elastic moduli, and the internal stress of the concrete test pieces is prone to being released due to force withdrawal are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete strength detection, specifically to a device and method for detecting the strength of concrete specimens before and after being frozen. Background Art

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

[0003] Currently, the method for detecting the strength of concrete specimens is to gradually apply pressure to the concrete specimens. During the pressure application process, the force cannot be withdrawn until the concrete specimens are damaged, and the ratio of the pressure and the force-bearing area when the concrete specimens are damaged is obtained to get the strength of the concrete specimens.

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

[0005] In high-altitude areas, it is also necessary to detect the strength of frozen concrete, which greatly increases the sample size. The strength detection efficiency of a large number of samples in the prior art needs to be improved, and there is a problem of too long waiting time for samples, which is likely to cause sample differences.

[0006] After the concrete is frozen, the formation of ice will increase the elastic modulus and strength of the concrete. When the weather warms up, the concrete strength will return to its true value.

[0007] The present invention is ingeniously designed so that a single press can detect two samples at the same time, overcoming the difficulties that when multiple concrete specimens are detected simultaneously, the inconsistent failure thresholds and elastic moduli are likely to affect the test results and the internal stress of the concrete specimens is easily released due to the withdrawal of force.

[0008] Therefore, a device and method for detecting the strength of concrete specimens before and after being frozen are proposed for the above problems. Summary of the Invention

[0009] The purpose of the present invention is to provide a device and method for detecting the strength of concrete specimens before and after being frozen, which can enable a single press to detect two samples at the same time, overcoming the problems that when multiple concrete specimens are detected simultaneously, the inconsistent failure thresholds and elastic moduli are likely to affect the test results and the internal stress of the concrete specimens is easily released due to the withdrawal of force.

[0010] To achieve the above object, the present invention provides the following technical solution: a strength detection device for concrete specimens before and after being frozen, including a base, a hydraulic cylinder fixedly installed on the base through a gantry, and further including upper and lower platen assemblies. The frozen concrete is placed between the base and the lower platen assembly, and the normal-temperature concrete is placed between the lower platen assembly and the upper platen assembly. The movable end of the hydraulic cylinder is fixedly connected to the top of the upper platen assembly for outputting pressure, and the frozen concrete and the normal-temperature concrete bear pressure simultaneously;

[0011] During the pressure application process, the normal-temperature concrete breaks first due to its lower strength. At this time, the anti-retreat component locks the lower platen assembly to prevent the internal stress of the frozen concrete from being released. As the movable end of the hydraulic cylinder descends, the bearing rod fixedly connected to the bottom end of the upper platen assembly contacts the lower platen assembly and continues to apply pressure to continue detecting the strength of the frozen concrete.

[0012] Preferably, as the strength detection device for concrete specimens before and after being frozen in the present invention, the height of the bearing rod is lower than the height of the concrete specimen to be measured.

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

[0014] In the present invention, the frozen concrete is artificially manufactured and taken out from the frozen environment during the detection. The present invention can greatly increase the detection efficiency of the strength of concrete specimens, and the efficiency is increased by nearly one time. To a certain extent, it avoids the problems of sample waiting or too long freezing time, which is likely to cause sample differences. The present invention is ingeniously designed so that a single press can detect two samples simultaneously, overcoming the difficulties that when multiple concrete specimens are detected simultaneously, the failure thresholds and elastic moduli are inconsistent, which easily affect the detection results of each other, and the internal stress of the concrete specimens is easily released due to the removal of the force;

[0015] During use, first place the frozen concrete between the base and the lower platen assembly, and place the normal-temperature concrete between the lower platen assembly and the upper platen assembly; then, by adjusting the movable end of the hydraulic cylinder and the lower platen assembly in a floating state, make the bottom end of the lower platen on the upper side align with the upper surface of the normal-temperature concrete, and the bottom end of the lower platen on the lower side align with the upper surface of the frozen concrete;

[0016] Secondly, the movable end of the hydraulic cylinder outputs pressure. During the pressing process, the normal-temperature concrete breaks first due to its low strength. The anti-retreat component locks the lower pressing plate component to prevent the release of internal stress in the frozen concrete. The force sensor in the upper pressing plate component obtains the applied pressure before the normal-temperature concrete breaks during the pressing process in real time. The maximum value of the pressure is the breaking pressure of the normal-temperature concrete, so as to obtain the strength of the normal-temperature concrete. Among them, in order to reduce the influence of the separation of fragments after the normal-temperature concrete breaks on the measurement, a shielding net can be arranged on the outer side above the lower pressing plate component;

[0017] Preferably, as the strength detection device for concrete specimens before and after freezing of the present invention, a second limiting rod is fixedly connected to the top end of the base. Connecting pieces are fixedly connected to the left and right ends of the upper bearing plate in the lower pressing plate component. The connecting pieces are distributed diagonally on the upper bearing plate. The connecting pieces are slidably connected to the outer side of the second limiting rod. After the normal-temperature concrete is placed on the lower pressing plate component, the lower pressing plate component can be suspended through the second limiting rod and the damper.

[0018] Preferably, as the strength detection device for concrete specimens before and after freezing of the present invention, a damper is fixedly connected to the inner side of one end of the connecting piece. The damper applies frictional force to the second limiting rod to counteract the gravity of the lower pressing plate component and the normal-temperature concrete, so that the compressive strengths of the normal-temperature concrete and the frozen concrete are the same.

[0019] Among them, the damper is a prior art and will not be elaborated here. Its internal general principle can be realized by a spring pushing a pressing plate to act on the second limiting rod. The damping force is adjusted by adjusting the compression degree of the spring;

[0020] Preferably, as the strength detection device for concrete specimens before and after freezing of the present invention, the damper is a variable damper, so that the damping of the damper can be adjusted to be suitable for concrete specimens of different weights.

[0021] Under the above settings, in order to make the compressive strengths of the normal-temperature concrete and the frozen concrete the same when the hydraulic cylinder does work, the present invention arranges the second limiting rod and the damper to suspend the lower pressing plate component. The damper applies frictional force to the second limiting rod to counteract the gravity of the lower pressing plate component and the normal-temperature concrete, avoiding the superposition of the gravity of the normal-temperature concrete and the lower pressing plate component on the frozen concrete, ensuring that under the same pressure of the hydraulic cylinder, the compressive strengths of the normal-temperature concrete and the frozen concrete are the same, and the normal-temperature concrete can break first due to its slightly lower strength;

[0022] Preferably, as a strength detection device for concrete specimens before and after freezing in the present invention, check members are fixedly connected to both the left and right ends of the upper bearing plate in the lower pressing plate assembly. The check members are distributed in a diagonal direction on the upper bearing plate. The anti-retreat assembly includes a driving member rotatable inside the base and a first limiting rod fixed on the base. The driving member can rotate, and a lead screw is fixedly connected to the top end of the driving member. The top end of the lead screw is rotatably connected to a top plate, and the bottom end of the top plate is fixedly connected to the top end of the first limiting rod. A pressing block is spirally connected to the outside of the lead screw, and the inner side of the pressing block is slidably connected to the outside of the first limiting rod. The pressing block can move downward following the check member to lock the lower pressing plate assembly.

[0023] In the present invention, the upward reset of the pressing block is achieved by the reverse rotation of the motor; after the normal-temperature concrete is crushed, the upper pressing plate assembly and the lower pressing plate assembly lose their hard connection. The anti-retreat assembly is used to lock the internal stress in the frozen concrete after the normal-temperature concrete is crushed, prevent the release of the internal stress in the frozen concrete, and ensure the continuous progress of the detection.

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

[0025] Under the above settings, the following movement of the pressing block is controlled by the pressing switch to ensure that the pressing block follows the check member.

[0026] Preferably, as a strength detection device for concrete specimens before and after freezing in the present invention, a motor is fixedly connected to the inner side of the base, and a coupling member is fixedly connected to the output end of the motor. The coupling member and the inner side of the driving member are magnetically coupled and driven. The motor keeps rotating, the lead screw rotates and drives the pressing block to follow the check member. After the pressing block and the check member are in close contact, the resistance of the pressing block increases, and the coupling member rotates independently. When the coupling member rotates independently, in order to avoid the pressing block generating a large downward pressure on the check member, by presetting the coupling strength, it is ensured that the downward pressure generated by the pressing block on the check member is relatively low and can be ignored.

[0027] The coupling member is rotatably connected to the driving member, and the coupling between the coupling member and the inner side of the driving member can also be achieved by the friction of friction plates.

[0028] As the movable end of the hydraulic cylinder descends, the pressure-bearing rod fixedly connected to the bottom end of the upper pressing plate assembly contacts the lower pressing plate assembly and continues to apply pressure to continue the strength detection of the frozen concrete. The force sensor in the lower pressing plate assembly obtains the applied pressure before the frozen concrete is crushed during the pressure application process in real time. The maximum value of the pressure is the crushing pressure of the frozen concrete, so as to obtain the strength of the frozen concrete.

[0029] The slider fixedly connected inside the connector is in sliding connection with the surface of the potentiometer. When the pressing plate assembly on the lower side moves downward, a displacement occurs between the surface of the potentiometer and the slider. The slider fixedly connected inside the potentiometer and the connector can obtain the deformation distance of the frozen concrete until before it is damaged. Combining with the compressive strength at the time of damage, the elastic modulus of the frozen concrete can be obtained;

[0030] The deformation distance of normal-temperature concrete until before it is damaged is equal to the extension distance of the hydraulic cylinder when normal-temperature concrete is damaged minus the deformation distance of the frozen concrete. Combining with the compressive strength at the time of damage, the elastic modulus of normal-temperature concrete can be obtained.

[0031] A method for detecting the strength of concrete specimens before and after being frozen, the steps of which are as follows:

[0032] Step 1: Place the frozen concrete between the base and the pressing plate assembly on the lower side, and place the normal-temperature concrete between the pressing plate assembly on the lower side and the pressing plate assembly on the upper side;

[0033] Step 2: Adjust the gap. By adjusting the movable end of the hydraulic cylinder and the pressing plate assembly on the lower side in a suspended state, make the bottom end of the lower pressing plate on the upper side align with the upper surface of the normal-temperature concrete, and the bottom end of the lower pressing plate on the lower side align with the upper surface of the frozen concrete;

[0034] Step 3: The movable end of the hydraulic cylinder outputs pressure. During the pressing process, the normal-temperature concrete breaks first due to its lower strength. The anti-retreat assembly locks the pressing plate assembly on the lower side to prevent the release of internal stress in the frozen concrete. The force sensor in the upper pressing plate assembly obtains the applied pressure before the normal-temperature concrete breaks during the pressing process in real time. The maximum value of the pressure is the breaking pressure of the normal-temperature concrete, so as to obtain the strength of the normal-temperature concrete;

[0035] Step 4: As the movable end of the hydraulic cylinder descends, the bearing rod fixedly connected to the bottom end of the upper pressing plate assembly contacts the pressing plate assembly on the lower side and continues to apply pressure, and continues to detect the strength of the frozen concrete. The force sensor in the lower pressing plate assembly obtains the applied pressure before the frozen concrete breaks during the pressing process in real time. The maximum value of the pressure is the breaking pressure of the frozen concrete, so as to obtain the strength of the frozen concrete.

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

[0037] 1. Strength detection device for concrete specimens before and after freezing. The present invention can greatly increase the detection efficiency of the strength of concrete specimens, with the efficiency nearly doubled. To a certain extent, it avoids the problems of long waiting time or freezing time of samples, which is likely to cause sample differences. Through ingenious design, the present invention enables a single press to detect two samples simultaneously, overcoming the difficulties that when multiple concrete specimens are detected simultaneously, the failure thresholds and elastic moduli are inconsistent, which easily affect the test results, and the internal stress of the concrete specimens is easily released due to the removal of force.

[0038] 2. Strength detection device for concrete specimens before and after freezing. In order to make the compressive strengths of normal-temperature concrete and frozen concrete consistent when the hydraulic cylinder works, the present invention sets a second limiting rod and a damper to suspend the lower pressing plate assembly. The damper resists the gravity of the lower pressing plate assembly and the normal-temperature concrete by applying frictional force to the second limiting rod, avoiding the superposition of the gravity of the normal-temperature concrete and the lower pressing plate assembly on the frozen concrete, ensuring that under the same pressure of the hydraulic cylinder, the compressive strengths of the normal-temperature concrete and the frozen concrete are consistent, and the normal-temperature concrete can be broken first due to slightly lower strength.

[0039] 3. Strength detection device for concrete specimens before and after freezing. After the normal-temperature concrete is broken, the upper pressing plate assembly and the lower pressing plate assembly lose the hard connection. The anti-retreat component is used to lock the internal stress in the frozen concrete after the normal-temperature concrete is broken, preventing the release of the internal stress in the frozen concrete and ensuring the continuous progress of the detection.

[0040] 4. Strength detection device for concrete specimens before and after freezing. The surface of the potentiometer is slidably connected to the slider fixedly connected inside the connecting piece. When the lower pressing plate assembly descends, the surface of the potentiometer and the slider generate displacement. The potentiometer and the slider fixedly connected inside the connecting piece can obtain the deformation distance of the frozen concrete until it is damaged. Combining with the compressive strength at the time of damage, the elastic modulus of the frozen concrete can be obtained. The deformation distance of the normal-temperature concrete until it is damaged is equal to the extension distance of the hydraulic cylinder when the normal-temperature concrete is damaged minus the deformation distance of the frozen concrete. Combining with the compressive strength at the time of damage, the elastic modulus of the normal-temperature concrete can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0043] Figure 3 It is a schematic diagram of the front view installation structure at the two pressing plate assemblies in the first embodiment of the present invention;

[0044] Figure 4 For the present invention Figure 3Schematic diagram of the enlarged structure at location A in

[0045] Figure 5 Front view installation structure diagram of two pressing plate assemblies in the second embodiment of the present invention;

[0046] Figure 6 The present invention Figure 5 Schematic diagram of the enlarged structure at location B in

[0047] Figure 7 Schematic diagram at step one during the strength detection process of the present invention;

[0048] Figure 8 Schematic diagram at step two during the strength detection process of the present invention;

[0049] Figure 9 Schematic diagram at step three during the strength detection process of the present invention;

[0050] Figure 10 Schematic diagram at step four during the strength detection process of the present invention;

[0051] Figure 11 Installation structure diagram of the potentiometer of the present invention.

[0052] In the figure: 1, base; 2, gantry; 3, hydraulic cylinder; 4, pressing plate assembly; 5, connecting piece; 6, damper; 7, check member; 8, first limiting rod; 9, driving member; 10, bearing rod; 11, lead screw; 12, second limiting rod; 13, top plate; 14, pressing block; 15, push button switch; 16, motor; 17, coupling member; 18, potentiometer; 19, slider;

[0053] 41, upper bearing plate; 42, lower pressing plate; 43, force sensor. Detailed implementation manners

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

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

[0056] Strength detection device for concrete specimens before and after being frozen, comprising a base 1, a hydraulic cylinder 3 fixedly connected and installed on the base 1 through a gantry 2, and further comprising upper and lower platen assemblies 4. The frozen concrete b is placed between the base 1 and the lower platen assembly 4, and the normal-temperature concrete a is placed between the lower platen assembly 4 and the upper platen assembly 4. The movable end of the hydraulic cylinder 3 is fixedly connected to the top end of the upper platen assembly 4 for outputting pressure, and the frozen concrete b and the normal-temperature concrete a bear pressure simultaneously;

[0057] During the pressure application process, the normal-temperature concrete a breaks first due to its lower strength. At this time, the anti-retreat assembly locks the lower platen assembly 4 to prevent the internal stress of the frozen concrete b from being released. As the movable end of the hydraulic cylinder 3 descends, the bearing rod 10 fixedly connected to the bottom end of the upper platen assembly 4 contacts the lower platen assembly 4 and continues to apply pressure to continue detecting the strength of the frozen concrete b.

[0058] Preferably, as the strength detection device for concrete specimens before and after being frozen in the present invention, the height of the bearing rod 10 is lower than the height of the concrete specimen to be measured.

[0059] Preferably, as the strength detection device for concrete specimens before and after being frozen in the present invention, each platen assembly 4 comprises an upper bearing plate 41 on the upper side and a lower platen 42 on the lower side. A force sensor 43 is fixedly connected between the upper bearing plate 41 and the lower platen 42 to obtain the applied pressure of the corresponding concrete specimen.

[0060] In the present invention, the frozen concrete b is artificially manufactured and taken out from the frozen environment during detection. The present invention can greatly increase the detection efficiency of the strength of concrete specimens, and the efficiency is increased by nearly one time. To a certain extent, it avoids the problems of sample waiting or too long freezing time, which is likely to cause sample differences. The present invention is ingeniously designed so that a single press can detect two samples simultaneously, overcoming the difficulties that when multiple concrete specimens are detected simultaneously, the failure thresholds and elastic moduli are inconsistent, which easily affect the detection results of each other, and the internal stress of the concrete specimens is easily released due to the removal of the force;

[0061] During use, first place the frozen concrete b between the base 1 and the lower platen assembly 4, and place the normal-temperature concrete a between the lower platen assembly 4 and the upper platen assembly 4; then, by adjusting the movable end of the hydraulic cylinder 3 and the lower platen assembly 4 in a suspended state, align the bottom end of the lower platen 42 on the upper side with the upper surface of the normal-temperature concrete a, and align the bottom end of the lower platen 42 on the lower side with the upper surface of the frozen concrete b;

[0062] Secondly, the movable end of the hydraulic cylinder 3 outputs pressure. During the pressing process, the normal-temperature concrete a breaks first due to its lower strength. The anti-retreat component locks the lower pressing plate component 4 to prevent the internal stress of the frozen concrete b from being released. The force sensor 43 in the upper pressing plate component 4 obtains the applied pressure before the normal-temperature concrete a breaks during the pressing process in real time. The maximum value of the pressure is the crushing pressure of the normal-temperature concrete a, so as to obtain the strength of the normal-temperature concrete a. Among them, in order to reduce the influence of the separation of the fragments after the normal-temperature concrete a breaks on the measurement, a shielding net can be arranged on the outer side of the upper side of the lower pressing plate component 4;

[0063] Preferably, as the strength detection device for concrete specimens before and after freezing of the present invention, a second limiting rod 12 is fixedly connected to the top end of the base 1. Connecting pieces 5 are fixedly connected to both the left and right ends of the upper bearing plate 41 in the lower pressing plate component 4. The connecting pieces 5 are distributed in a diagonal direction on the upper bearing plate 41. The connecting pieces 5 are slidably connected to the outer side of the second limiting rod 12. After the normal-temperature concrete a is placed on the lower pressing plate component 4, the lower pressing plate component 4 can be suspended through the second limiting rod 12 and the damper 6.

[0064] Preferably, as the strength detection device for concrete specimens before and after freezing of the present invention, a damper 6 is fixedly connected to the inner side of one end of the connecting piece 5. The damper 6 exerts a frictional force on the second limiting rod 12 to counteract the gravity of the lower pressing plate component 4 and the normal-temperature concrete a, so as to make the compressive strengths of the normal-temperature concrete a and the frozen concrete b consistent.

[0065] Among them, the damper is a prior art and will not be elaborated here. Its internal general principle can be realized by a spring pushing a pressing plate to act on the second limiting rod 12, and the damping force is adjusted by adjusting the compression degree of the spring;

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

[0067] Under the above settings, in order to make the compressive strengths of the normal-temperature concrete a and the frozen concrete b consistent when the hydraulic cylinder 3 does work, the present invention sets the second limiting rod 12 and the damper 6 to suspend the lower pressing plate component 4. The damper 6 counteracts the gravity of the lower pressing plate component 4 and the normal-temperature concrete a by exerting a frictional force on the second limiting rod 12, avoiding the superposition of the gravity of the normal-temperature concrete a and the lower pressing plate component 4 on the frozen concrete b, and ensuring that under the same pressure of the hydraulic cylinder 3, the compressive strengths of the normal-temperature concrete a and the frozen concrete b are consistent, and the normal-temperature concrete a can break first due to its slightly lower strength;

[0068] Preferably, as a strength detection device for concrete specimens before and after being frozen in the present invention, check parts 7 are fixedly connected to both the left and right ends of the upper bearing plate 41 in the lower pressing plate assembly 4. The check parts 7 are distributed in a diagonal direction on the upper bearing plate 41. The anti-retreat assembly includes a driving part 9 rotatably arranged inside the base 1 and a first limiting rod 8 fixed on the base 1. The driving part 9 can rotate. A lead screw 11 is fixedly connected to the top end of the driving part 9. 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. A pressing block 14 is helically connected to the outside of the lead screw 11. The inner side of the pressing block 14 is slidably connected to the outside of the first limiting rod 8. The pressing block 14 can move downward following the check part 7 to lock the lower pressing plate assembly 4.

[0069] In the present invention, the upward reset of the pressing block 14 is realized by the reverse rotation of the motor. After the normal-temperature concrete a is broken, the upper pressing plate assembly 4 and the lower pressing plate assembly 4 lose the hard connection. The anti-retreat assembly is used to lock the internal stress in the frozen concrete b after the normal-temperature concrete a is broken, prevent the release of the internal stress in the frozen concrete b, and ensure the continuous progress of the detection.

[0070] Preferably, as a strength detection device for concrete specimens before and after being frozen in the present invention, the driving part 9 is a motor. A pressing switch 15 is fixedly connected to the inner side of the pressing block 14. When the check part 7 is loosened from the pressing block 14, the pressing switch 15 is released, and the motor can rotate. The motor drives the lead screw 11 to rotate. The rotation of the lead screw 11 forces the pressing block 14 to move downward to follow the check part 7. When the check part 7 is completely close to the pressing block 14, the pressing switch 15 is pressed, and the motor can stop, so that the check part 7 and the pressing block 14 remain close.

[0071] Under the above settings, the following movement of the pressing block 14 is controlled by the pressing switch 15 to ensure that the pressing block 14 follows the check part 7.

[0072] As the movable end of the hydraulic cylinder 3 probes downward, the bearing rod 10 fixedly connected to the bottom end of the upper pressing plate assembly 4 contacts the lower pressing plate assembly 4 and continues to apply pressure, and continues to detect the strength of the frozen concrete b. The force sensor 43 in the lower pressing plate assembly 4 obtains in real time the applied pressure before the frozen concrete b is broken during the pressure application process. The highest value of the pressure is the breaking pressure of the frozen concrete b, so as to obtain the strength of the frozen concrete b.

[0073] Embodiment 2. This embodiment is another way of Embodiment 1. The same parts will not be described in detail. Please refer to Figures 1-2 , Figures 5-10A motor 16 is fixedly connected to the inner side of the base 1. The output end of the motor 16 is fixedly connected with a coupling member 17. The coupling member 17 and the inner side of the driving member 9 are in magnetic coupling transmission. The motor 16 keeps rotating, the lead screw 11 rotates and drives the pressing block 14 to move along with the check member 7. After the pressing block 14 is in close contact with the check member 7, the resistance of the pressing block 14 increases, and the coupling member 17 rotates independently. When the coupling member 17 rotates independently, in order to avoid the pressing block 14 generating a large downward pressure on the check member 7, by presetting the coupling strength, after being in close contact, as the resistance of the pressing block 14 increases, the power is cut off in time to ensure that the downward pressure generated by the pressing block 14 on the check member 7 is relatively low and can be ignored;

[0074] The coupling member 17 is rotatably connected to the driving member 9. The coupling between the coupling member 17 and the inner side of the driving member 9 can also be carried out by means of friction between friction plates.

[0075] Embodiment 3 is a supplement to Embodiments 1 and 2. The same parts will not be described in detail. The surface of the potentiometer 18 is slidably connected to the slider 19 fixedly connected inside the connecting member 5. When the lower pressing plate assembly 4 on the lower side descends, a displacement is generated between the surface of the potentiometer 18 and the slider 19. The potentiometer 18 and the slider 19 fixedly connected inside the connecting member 5 can obtain the deformation distance of the frozen concrete b until before damage. Combining with the compressive strength at the time of damage, the elastic modulus of the frozen concrete b can be obtained;

[0076] The deformation distance of the normal-temperature concrete b until before damage is equal to the extension distance of the hydraulic cylinder 3 when the normal-temperature concrete b is damaged minus the deformation distance of the frozen concrete a. Combining with the compressive strength at the time of damage, the elastic modulus of the normal-temperature concrete a can be obtained.

[0077] The present invention also discloses a method for detecting the strength of concrete specimens before and after being frozen, and the steps are as follows:

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

[0079] Step 2: Adjust the gap. By adjusting the movable end of the hydraulic cylinder 3 and the lower pressing plate assembly 4 in a suspended state, the bottom end of the lower pressing plate 42 on the upper side is aligned with the upper surface of the normal-temperature concrete a, and the bottom end of the lower pressing plate 42 on the lower side is aligned with the upper surface of the frozen concrete b;

[0080] Step 3: The movable end of the hydraulic cylinder 3 outputs pressure. During the pressing process, the normal-temperature concrete a breaks first due to its lower strength. The anti-retreat assembly locks the lower pressing plate assembly 4 to prevent the internal stress of the frozen concrete b from being released. The force sensor 43 in the upper pressing plate assembly 4 obtains the applied pressure before the normal-temperature concrete a breaks during the pressing process in real time. The highest value of the pressure is the breaking pressure of the normal-temperature concrete a, so as to obtain the strength of the normal-temperature concrete a;

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

[0082] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Strength detection device for concrete specimens before and after being frozen, comprising a base (1) and a hydraulic cylinder (3) fixedly connected and installed on the base (1) through a gantry (2), characterized in that: It also includes two upper and lower platen assemblies (4). The frozen concrete (b) is placed between the base (1) and the lower platen assembly (4), and the normal-temperature concrete (a) is placed between the lower platen assembly (4) and the upper platen assembly (4). The movable end of the hydraulic cylinder (3) is fixedly connected to the top end of the upper platen assembly (4) for outputting pressure, and the frozen concrete (b) and the normal-temperature concrete (a) bear pressure simultaneously. During the pressure application process, the normal-temperature concrete (a) breaks first due to its lower strength. At this time, the anti-retreat component locks the lower platen assembly (4) to prevent the release of internal stress in the frozen concrete (b). As the movable end of the hydraulic cylinder (3) descends, the bearing rod (10) fixedly connected to the bottom end of the upper platen assembly (4) contacts the lower platen assembly (4) and continues to apply pressure to continue testing the strength of the frozen concrete (b).

2. The strength detection device for concrete specimens before and after being frozen according to claim 1, wherein: The height of the bearing rod (10) is lower than the height of the concrete specimen to be measured.

3. The strength detection device for concrete specimens before and after freezing according to claim 2, characterized in that: Each platen assembly (4) includes an upper bearing plate (41) on the upper side and a lower platen (42) on the lower side. A force sensor (43) is fixedly connected between the upper bearing plate (41) and the lower platen (42) to obtain the applied pressure of the corresponding concrete specimen.

4. The strength detection device for concrete specimens before and after being frozen according to any one of claims 1-3, characterized in that: A second limiting rod (12) is fixedly connected to the top end of the base (1). Connecting pieces (5) are fixedly connected to both the left and right ends of the upper bearing plate (41) in the lower platen assembly (4). The connecting pieces (5) are distributed diagonally on the upper bearing plate (41). The connecting pieces (5) are slidably connected to the outer side of the second limiting rod (12). After the normal-temperature concrete (a) is placed on the lower platen assembly (4), the lower platen assembly (4) can be suspended through the second limiting rod (12) and the damper (6).

5. The strength detection device for concrete specimens before and after freezing according to claim 4, wherein: A damper (6) is fixedly connected to the inner side of one end of the connecting piece (5). The damper (6) applies frictional force to the second limiting rod (12) to counteract the gravity of the lower platen assembly (4) and the normal-temperature concrete (a), so that the compressive strengths of the normal-temperature concrete (a) and the frozen concrete (b) are consistent.

6. The strength detection device for concrete specimens before and after being frozen according to claim 5, characterized in that: The damper (6) is a variable damper, so that the damping of the damper (6) can be adjusted to be suitable for concrete specimens of different weights.

7. The strength detection device for concrete specimens before and after being frozen according to claim 4, characterized in that: Check valves (7) are fixedly connected to both the left and right ends of the upper bearing plate (41) in the lower platen assembly (4). The check valves (7) are distributed diagonally on the upper bearing plate (41). The anti-retreat component includes a driving part (9) rotating inside the base (1) and a first limiting rod (8) fixed on the base (1). The driving part (9) can rotate. A lead screw (11) is fixedly connected to the top end of the driving part (9). 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). A pressing block (14) is helically connected to the outer side of the lead screw (11). The inner side of the pressing block (14) is slidably connected to the outer side of the first limiting rod (8). The pressing block (14) can move downward following the check valve (7) to lock the lower platen assembly (4).

8. The strength detection device for concrete specimens before and after being frozen as claimed in claim 7, wherein: The driving member (9) is a motor. A pressing switch (15) is fixedly connected to the inner side of the pressing block (14). When the check member (7) is disengaged from the pressing block (14), the pressing switch (15) is released, and the motor can rotate, causing the pressing block (14) to move along with the check member (7). When the check member (7) is completely close to the pressing block (14), the pressing switch (15) is pressed, and the motor can stop.

9. The strength detection device for concrete specimens before and after being frozen according to claim 7, characterized in that: A motor (16) is fixedly connected to the inner side of the base (1). The output end of the motor (16) is fixedly connected to a coupling member (17). The coupling member (17) and the inner side of the driving member (9) are in magnetic coupling transmission. After the pressing block (14) moves downward along with the check member (7) and is in close contact with the check member (7), the resistance of the pressing block (14) increases, and the coupling member (17) rotates independently.

10. Method for detecting the strength of a concrete specimen before and after freezing, using the strength detection device for a concrete specimen before and after freezing as described in claim 9, characterized in that, The steps are as follows: Step 1: Place the frozen concrete (b) between the base (1) and the lower pressing plate assembly (4), and place the normal-temperature concrete (a) between the lower pressing plate assembly (4) and the upper pressing plate assembly (4). Step 2: Adjust the gap. By adjusting the movable end of the hydraulic cylinder (3) and the lower pressing plate assembly (4) in a floating state, align the bottom end of the lower pressing plate (42) on the upper side with the upper surface of the normal-temperature concrete (a), and align the bottom end of the lower pressing plate (42) on the lower side with the upper surface of the frozen concrete (b). Step 3: The movable end of the hydraulic cylinder (3) outputs pressure. During the pressing process, the normal-temperature concrete (a) breaks first due to its lower strength. The anti-retreat assembly locks the lower pressing plate assembly (4) to prevent the release of internal stress in the frozen concrete (b). The force sensor (43) in the upper pressing plate assembly (4) obtains the applied pressure before the normal-temperature concrete (a) breaks during the pressing process in real time. The maximum value of the pressure is the crushing pressure of the normal-temperature concrete (a), thereby obtaining the strength of the normal-temperature concrete (a). Step 4: As the movable end of the hydraulic cylinder (3) descends, the bearing rod (10) fixedly connected to the bottom end of the upper pressing plate assembly (4) contacts the lower pressing plate assembly (4) and continues to apply pressure, continuing to detect the strength of the frozen concrete (b). The force sensor (43) in the lower pressing plate assembly (4) obtains the applied pressure before the frozen concrete (b) breaks during the pressing process in real time. The maximum value of the pressure is the crushing pressure of the frozen concrete (b), thereby obtaining the strength of the frozen concrete (b).

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