Concrete shrinkage test device and experimental method thereof

Abstract

The application provides a concrete shrinkage test device and an experimental method thereof, which comprises an aluminum alloy support and two detection mechanisms, the detection mechanisms are located at the top of the aluminum alloy support, and the detection mechanisms comprise support blocks. In the application, the detection mechanisms automatically detect the concrete test piece to be measured through a transmission mechanism, which can avoid the measurement errors caused by manual multiple adjustments, improve the accuracy of measurement, and the leveling mechanism can directly contact and measure the concrete test piece to be measured through the micrometer measuring rod. Some recessed parts inevitably exist on the concrete test piece to be measured. If the data obtained by the measuring rod contacting the recessed parts during detection is not accurate enough, the final obtained concrete shrinkage data will also be inaccurate. In addition, the dust removal mechanism can blow air to the contact position of the leveling frame and the concrete test piece to be measured, blow off the floating dust on the surface, clean the floating dust, and improve the detection accuracy.

Description

A concrete shrinkage testing device and its experimental method Technical Field

[0001] This invention relates to the field of concrete shrinkage technology, specifically to a concrete shrinkage testing device and its experimental method. Background Technology

[0002] Concrete shrinkage refers to the reduction in volume that occurs during the initial setting or hardening process of concrete. It is generally classified into plastic shrinkage (also known as settling shrinkage), chemical shrinkage (also known as intrinsic shrinkage), drying shrinkage, and carbonation shrinkage. Significant shrinkage can cause concrete cracking. To ensure that the quality of concrete used in construction meets building standards, concrete shrinkage testing equipment is used to calculate the shrinkage rate of the concrete, thereby determining whether the concrete meets the required standards.

[0003] The invention disclosed in publication number "CN113075391A" provides a concrete restrained shrinkage testing device and method, comprising a base plate, two end plates arranged opposite each other along the length of the base plate, angle steel disposed at the corners of the end plates, and displacement sensors disposed on the base plate; the displacement sensors are disposed on the two sides of the end plates away from the base plate; the two end plates together form a device for restraining the shrinkage deformation of the concrete specimen under test along its length; the concrete specimen under test includes two thin plates embedded in the top of the concrete specimen under test and reinforcing bars embedded in both ends of the concrete specimen under test; the reinforcing bars are used to restrain concrete shrinkage, and the thin plates are used to observe the shrinkage deformation in the middle part of the concrete specimen under test; the invention has a simple structure, is easy to operate, and has high accuracy.

[0004] However, the above-mentioned device still has the following problems during implementation:

[0005] Existing concrete shrinkage testing equipment requires manual placement of the concrete specimen during testing. The specimen's position is adjusted, and data is obtained by observing the dial indicator readings. This process is prone to errors, leading to inaccurate concrete shrinkage data. Furthermore, since the dial indicator probe directly contacts the specimen, any indentations or depressions on the specimen will also result in inaccurate data, further contributing to the final, less accurate concrete shrinkage readings. Summary of the Invention

[0006] The purpose of this invention is to provide a concrete shrinkage testing device and its testing method to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A concrete shrinkage testing device and its testing method include an aluminum alloy bracket and two testing mechanisms. The testing mechanisms are located on top of the aluminum alloy bracket. Each testing mechanism includes a support block. A dial indicator is fixedly installed on one side of the support block, and the measuring rod of the dial indicator extends through one side of the support block.

[0009] The transmission mechanism is fixedly mounted on an aluminum alloy bracket and can control the dial indicator to approach the concrete specimen to be tested and detect the shrinkage of the concrete specimen.

[0010] A leveling mechanism is fixedly mounted on a support block. Before the dial indicator probe contacts the concrete specimen to be tested, the leveling mechanism will contact the concrete specimen in advance. Subsequently, when the dial indicator probe contacts the leveling mechanism, the required shrinkage data of the concrete specimen to be tested can be obtained, thereby ensuring the accuracy of the test data.

[0011] Preferably, the transmission mechanism includes a motor, which is fixedly installed at the bottom of the aluminum alloy bracket. A first helical gear is fixedly connected to the output end of the motor. Second helical gears are meshed on both sides of the first helical gear. A lead screw is fixedly connected to one side of the second helical gear. A moving block is threaded onto the surface of the lead screw. A sliding block is fixedly connected to the top of the moving block. The top of the sliding block extends through to the top of the aluminum alloy bracket and is fixedly connected to the bottom of the support block. A sliding groove is provided on the top of the aluminum alloy bracket to cooperate with the sliding block.

[0012] Preferably, the leveling mechanism includes a leveling frame, two springs are fixedly connected to one side of the leveling frame, one end of the spring is fixedly connected to one side of the support block, a guide post is provided inside the spring, and a guide hole is provided on one side of the leveling frame to cooperate with the guide post.

[0013] A dust removal mechanism is provided on one side of the leveling frame, which can clean the floating dust generated by compression when the leveling frame comes into contact with the concrete specimen to be tested, thereby improving the accuracy of the test data.

[0014] Preferably, the dust removal mechanism includes an air collecting cylinder, one end of which is fixedly connected to one side of an aluminum alloy bracket, an air inlet pipe fixedly connected to the bottom of the air collecting cylinder, an exhaust pipe (32) fixedly connected to the top of the air collecting cylinder, an air collecting box fixedly connected to one end of the exhaust pipe (32), a support frame fixedly connected to one side of the air collecting box, the bottom of the support frame fixedly connected to the top of a support block, a blowing pipe fixedly connected to the bottom of the air collecting box via a solenoid valve, a squeezing block provided inside the air collecting cylinder, a piston fixedly connected to one side of the squeezing block, a squeezing rod fixedly connected to one side of the piston, one end of the squeezing rod penetrating into the interior of the aluminum alloy bracket and fixedly connected to a connecting block, and the top of the connecting block fixedly connected to the bottom of a moving block.

[0015] A touch sensor for controlling the solenoid valve is fixedly installed at the bottom of the flattening frame, and a touch rod is fixedly connected to one side of the support block, with the touch rod and the touch sensor being positioned opposite each other.

[0016] Preferably, one end of the lead screw is provided with a bearing, and one end of the lead screw is rotatably connected to the inner wall of the aluminum alloy bracket through the bearing.

[0017] Preferably, a threaded hole is provided on one side of the movable block, and the threaded hole is used in conjunction with the lead screw.

[0018] Preferably, one side of the gas collecting cylinder has a movable hole for use with the extrusion rod, and the inner wall of the movable hole is fixedly connected with a sealing ring for use with the extrusion rod.

[0019] Preferably, a first one-way valve is fixedly installed on the surface of the intake pipe, and a second one-way valve is fixedly installed on the surface of the exhaust pipe (32).

[0020] Preferably, the outer surface of the piston is in close contact with the inner wall of the gas collecting cylinder, and the material is rubber.

[0021] A preferred experimental method,

[0022] S1: First, place the concrete specimen to be tested in the center of the aluminum alloy bracket, and then start the transmission mechanism to move the dial indicator in the testing mechanism closer to the concrete specimen to be tested.

[0023] S2: At the same time, the leveling mechanism will first come into contact with the surface of the concrete specimen. Then, under the influence of pressure, the leveling mechanism will shrink, so as to come into contact with the dial indicator rod, thereby avoiding the dial indicator rod from contacting the depression on the concrete specimen to be tested.

[0024] S3: At the same time, the dust removal mechanism will blow out gas to clean the floating dust generated when the leveling mechanism comes into contact with the concrete specimen, so as to avoid the floating dust affecting the accuracy of the measurement.

[0025] S4: Then, when the value on the dial indicator is between five and ten millimeters, record the data on both dial indicators simultaneously.

[0026] S5: After standing for 24 hours, record the data on the two dial gauges again, compare them with the previous records, and calculate the shrinkage rate of the concrete specimen based on the data.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. By setting up a testing mechanism, this invention can detect the shrinkage of the concrete specimen under test using two dial gauges, resulting in more accurate data and improved testing precision.

[0029] 2. This invention, by setting up a transmission mechanism, can automatically move the dial indicator to the concrete specimen to be tested for measurement. After recording the data, the shrinkage rate of the concrete specimen can be calculated. Through automated operation, it can effectively avoid the inaccuracy of measurement results caused by manual adjustment of the concrete specimen. It solves the problem that existing concrete shrinkage testing devices require manual placement of the concrete specimen, adjustment of its position, and observation of the dial indicator value during operation, which is prone to errors and leads to inaccurate concrete shrinkage data.

[0030] 3. This invention, by setting up a leveling mechanism, can simultaneously move the support block, which drives the dial indicator to move closer to the concrete specimen, and also move the leveling frame closer to the concrete specimen. The leveling frame will first contact the surface of the concrete specimen, and then, under pressure, the spring will contract. At the same time, the back of the leveling frame will contact the dial indicator probe. At this time, the data transmitted by the leveling frame is more accurate than the average value of the surface of the concrete specimen, and the data displayed on the dial indicator is also more accurate. As the concrete specimen shrinks, the spring pushes the leveling frame to always be in contact with the surface of the concrete specimen, and the data on the dial indicator will also change. This solves the problem that when measuring by directly contacting the concrete specimen with the dial indicator probe, there are inevitably some depressions on the concrete specimen. If the probe contacts these depressions during the test, the data obtained will inevitably be inaccurate, which will also lead to inaccurate concrete shrinkage data in the end.

[0031] 4. This invention, by setting up a dust removal mechanism, allows the moving block to move closer to the concrete specimen to be tested. Simultaneously, the dust removal mechanism works in conjunction with the touch sensor and the touch rod. At this time, the solenoid valve is activated, and the gas in the air collection box is discharged from the air blowing pipe, which blows air onto the contact point between the leveling frame and the concrete specimen to be tested, blowing off the surface dust and achieving the effect of cleaning the dust. This solves the problem that some dust inevitably accumulates on the surface of the leveling frame when it comes into contact with the concrete specimen, affecting the test results.

[0032] In this invention, the transmission mechanism controls the testing mechanism to automatically test the concrete specimen, avoiding measurement errors caused by multiple manual adjustments and affecting measurement accuracy. Simultaneously, the leveling mechanism allows direct contact measurement between the dial indicator probe and the concrete specimen. Since some depressions are inevitable on the specimen, data obtained from contact with these depressions during testing will be inaccurate, leading to inaccurate concrete shrinkage data. Furthermore, the dust removal mechanism blows air onto the contact area between the leveling frame and the concrete specimen, removing surface dust and improving testing accuracy. Attached Figure Description

[0033] Figure 1 is a schematic diagram of the main structure of the present invention;

[0034] Figure 2 is a perspective view of the present invention in cross-section;

[0035] Figure 3 is a perspective view of a partial structure of the present invention;

[0036] Figure 4 is a partial enlarged view of point A in Figure 3 of this invention;

[0037] Figure 5 is a perspective view of a partial structure of the present invention from the side;

[0038] Figure 6 is a perspective view of a partial structure of the present invention;

[0039] Figure 7 is a perspective view of a partial cross-section of the present invention;

[0040] Figure 8 is a perspective view of a partial structure of the present invention;

[0041] Figure 9 is a schematic diagram of a partial structure of the present invention.

[0042] In the diagram: 1. Aluminum alloy bracket; 2. Support block; 3. Dial indicator; 4. Motor; 5. First helical gear; 6. Second helical gear; 7. Lead screw; 8. Moving block; 9. Sliding block; 10. Sliding groove; 11. Leveling frame; 12. Spring; 13. Guide column; 14. Guide hole; 15. Air collection cylinder; 16. Air inlet pipe; 17. Air collection box; 18. Support frame; 19. Air blowing pipe; 20. Extrusion block; 21. Piston; 22. Extrusion rod; 23. Connecting block; 24. Touch sensor; 25. Touch rod; 26. Bearing; 27. Threaded hole; 28. Movable hole; 29. ​​Sealing ring; 30. First one-way valve; 31. Second one-way valve; 32. Exhaust pipe. Detailed Implementation

[0043] 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.

[0044] Please refer to Figures 1-9. This invention provides a technical solution:

[0045] Example 1:

[0046] A concrete shrinkage testing device and its testing method include an aluminum alloy bracket 1 and two testing mechanisms. The testing mechanisms are located on the top of the aluminum alloy bracket 1. Each testing mechanism includes a support block 2. A dial indicator 3 is fixedly installed on one side of the support block 2, and the measuring rod of the dial indicator 3 extends through to one side of the support block 2.

[0047] By setting up a testing facility, the shrinkage of the concrete specimens under test can be detected using two dial gauges, resulting in more accurate data and improved testing precision.

[0048] The transmission mechanism is fixedly mounted on the aluminum alloy bracket 1, which can control the dial gauge 3 to approach the concrete specimen to be tested and detect the shrinkage of the concrete specimen.

[0049] The leveling mechanism is fixedly installed on the support block 2. Before the dial gauge 3 probe contacts the concrete specimen to be tested, the leveling mechanism will contact the concrete specimen in advance. After the dial gauge 3 probe contacts the leveling mechanism, the required shrinkage data of the concrete specimen to be tested can be obtained, thereby ensuring the accuracy of the test data.

[0050] Preferably, the transmission mechanism includes a motor 4, which is fixedly installed at the bottom of the aluminum alloy bracket 1. The output end of the motor 4 is fixedly connected to a first helical gear 5. Both sides of the first helical gear 5 are meshed with second helical gears 6. One side of the second helical gear 6 is fixedly connected to a lead screw 7. The surface of the lead screw 7 is threadedly connected to a moving block 8. The top of the moving block 8 is fixedly connected to a sliding block 9. The top of the sliding block 9 extends through to the top of the aluminum alloy bracket 1 and is fixedly connected to the bottom of the support block 2. The top of the aluminum alloy bracket 1 is provided with a sliding groove 10 that cooperates with the sliding block 9.

[0051] By setting up a transmission mechanism, the motor 4 can drive the first helical gear 5 to rotate. Since the first helical gear 5 meshes with the second helical gear 6, the rotation of the first helical gear 5 will drive the second helical gear 6 and the lead screw 7 to rotate. When the lead screw 7 rotates, the external thread on its surface will squeeze the internal thread in the threaded hole 27, so that the moving block 8 can only move along the trajectory of the sliding groove 10 to slowly move the sliding block 9, the support block 2, the dial indicator 3 and the leveling mechanism to the side closer to the concrete specimen to be tested. Then the leveling mechanism contacts the concrete specimen to be tested first, and then the measuring rod of the dial indicator 3 contacts the leveling frame 11 in the leveling mechanism. When the data on the dial indicator 3 is between five and ten millimeters, it is ready. After resting for twenty-four hours, the data on the dial indicator 3 is recorded again, and the shrinkage rate of the concrete specimen to be tested can be obtained by calculation. Through automated operation, the measurement results can be effectively avoided due to multiple manual adjustments of the concrete specimen to be tested.

[0052] This invention solves the problem that existing concrete shrinkage testing devices require manual placement of the concrete specimens during testing. The specimens are then adjusted, and the data is obtained by observing the values ​​on the dial gauge. This process is prone to errors, leading to inaccurate concrete shrinkage data.

[0053] Meanwhile, the threaded holes 27 on the two moving blocks 8 are opposite threads. Therefore, when the lead screw 7 rotates, when its external thread is pressed against the internal thread of the threaded hole 27, the two moving blocks 8 will cause the sliding block 9, support block 2, dial indicator 3 and leveling mechanism to move towards each other. This is a common technique used by those skilled in the art, so it will not be described in detail here.

[0054] Preferably, a bearing 26 is provided at one end of the lead screw 7, and one end of the lead screw 7 is rotatably connected to the inner wall of the aluminum alloy bracket 1 through the bearing 26;

[0055] By setting the bearing 26, the lead screw 7 can be rotatably connected to the inner wall of the aluminum alloy bracket 1 through the bearing 26, which can provide a supporting force for the lead screw 7, and at the same time make it rotate only when the second helical gear 6 rotates, and restrict the position of the second helical gear 6, so that the second helical gear 6 and the first helical gear 5 always remain in a meshing state.

[0056] Preferably, a threaded hole 27 is provided on one side of the movable block 8, and the threaded hole 27 is used in conjunction with the lead screw 7;

[0057] By setting the threaded hole 27, while the lead screw 7 is rotating, the external thread on its surface will squeeze the internal thread in the threaded hole 27, so that the moving block 8 and other structures move along the trajectory of the sliding groove 10, thus playing a transmission role.

[0058] Example 2:

[0059] Based on Embodiment 1, this embodiment solves the problem of inaccurate concrete shrinkage data when placing concrete specimens on a concrete shrinkage testing device by automation. This is because the existing method requires manual placement of the concrete specimens, adjustment of their position, and observation of the values ​​on the dial gauge 3. Errors are easily generated during this process. Furthermore, the surface of existing concrete specimens inevitably has depressions, making accurate data difficult to obtain even with direct contact testing using the dial gauge 3. In this invention, the leveling mechanism includes a leveling frame 11. Two springs 12 are fixedly connected to one side of the leveling frame 11. One end of each spring 12 is fixedly connected to one side of the support block 2. A guide post 13 is provided inside each spring 12. A guide hole 14, which cooperates with the guide post 13, is provided on one side of the leveling frame 11.

[0060] A dust removal mechanism is provided on one side of the leveling frame 11, which can clean the floating dust generated by compression when the leveling frame 11 comes into contact with the concrete specimen to be tested, thereby improving the accuracy of the test data.

[0061] By setting up a leveling mechanism, while the support block 2 moves the dial indicator 3 closer to the concrete specimen to be tested, it also moves the leveling frame 11 closer to the concrete specimen to be tested. The leveling frame 11 will first contact the surface of the concrete specimen to be tested, and then be compressed by pressure. The spring 12 will contract, and at the same time, the back of the leveling frame 11 will contact the measuring rod of the dial indicator 3. At this time, the data transmitted by the leveling frame 11 is more accurate than the average value of the surface of the concrete specimen to be tested. The data displayed on the dial indicator 3 is also more accurate. As the concrete specimen to be tested contracts, the spring 12 pushes the leveling frame 11 to always contact the surface of the concrete specimen to be tested, and the data on the dial indicator 3 will also change.

[0062] This solves the problem that when measuring concrete specimens by directly contacting the measuring rod of a dial indicator 3, there will inevitably be some depressions on the concrete specimens. If the measuring rod is in contact with these depressions during the test, the data obtained will inevitably be inaccurate, which will also lead to inaccurate concrete shrinkage data in the end.

[0063] The leveling frame 11 in this application can only move along the trajectory of the guide column 13 due to the restriction of the guide column 13. Meanwhile, the dial indicator 3 is prior art and is known to those skilled in the art, so it will not be described in detail here.

[0064] Example 3:

[0065] Based on Embodiment 2, although the leveling mechanism in this embodiment can contact the surface of the concrete specimen to be tested and then be compressed by pressure, causing the spring 12 to contract, and at the same time the back of the leveling frame 11 will contact the measuring rod of the dial indicator 3, thus avoiding the problem of inaccurate test data caused by the measuring rod of the dial indicator 3 contacting the concave area of ​​the surface of the concrete specimen to be tested, some floating dust will inevitably be generated on the surface of the leveling frame 11 when it comes into contact with the concrete specimen to be tested, affecting the test effect. In this invention, the dust removal mechanism includes an air collecting cylinder 15, one end of which is fixedly connected to one side of the aluminum alloy bracket 1, and the bottom of the air collecting cylinder 15 is fixedly connected to... An exhaust pipe 32 is fixedly connected to the top of the air inlet pipe 16 and the air collection cylinder 15. One end of the exhaust pipe 32 is fixedly connected to the air collection box 17. A support frame 18 is fixedly connected to one side of the air collection box 17. The bottom of the support frame 18 is fixedly connected to the top of the support block 2. The bottom of the air collection box 17 is fixedly connected to the air blowing pipe 19 through a solenoid valve. An extrusion block 20 is provided inside the air collection cylinder 15. A piston 21 is fixedly connected to one side of the extrusion block 20. An extrusion rod 22 is fixedly connected to one side of the piston 21. One end of the extrusion rod 22 penetrates into the interior of the aluminum alloy bracket 1 and is fixedly connected to a connecting block 23. The top of the connecting block 23 is fixedly connected to the bottom of the moving block 8.

[0066] A touch sensor 24 for controlling the solenoid valve is fixedly installed at the bottom of the leveling frame 11, and a touch rod 25 is fixedly connected to one side of the support block 2, with the touch rod 25 and the touch sensor 24 being opposite each other.

[0067] By setting up a dust removal mechanism, the moving block 8 can move closer to the concrete specimen to be tested, while simultaneously moving the connecting block 23, the extrusion rod 22, the piston 21, and the extrusion block 20. At the same time, the piston 21 will extrude gas into the exhaust pipe 32 and then into the gas collection box 17. After the leveling frame 11 comes into contact with the concrete specimen to be tested and is extruded to the designated position, the touch sensor 24 contacts the touch rod 25. At this time, the solenoid valve is activated, and the gas in the gas collection box 17 will be discharged from the air blowing pipe 19, which blows air onto the contact position between the leveling frame 11 and the concrete specimen to be tested, blowing off the surface dust and achieving the effect of cleaning the surface dust.

[0068] This solves the problem that when the flattening frame 11 comes into contact with the concrete specimen to be tested, some floating dust will inevitably be generated on its surface, which will affect the test results;

[0069] Meanwhile, the bottom of the gas collection tube is designed with an air inlet pipe 16 with a first one-way valve 30 installed, which can ensure that enough gas enters the gas collection box 17 each time the gas collection cylinder 15 is squeezed. At the same time, the air blowing pipe 19 will exhaust the gas each time the concrete specimen to be tested is tested, so there is no need to worry about the gas compression force inside the gas collection box 17 being too large and affecting the operation of the structure.

[0070] Preferably, one side of the gas collecting cylinder 15 has a movable hole 28 for use with the extrusion rod 22, and a sealing ring 29 for use with the extrusion rod 22 is fixedly connected to the inner wall of the movable hole 28.

[0071] By providing a movable hole 28 and a sealing ring 29, the movable hole 28 provides a space for the extrusion rod 22 to move, while the sealing ring 29 ensures that no gas leakage is detected when the extrusion rod 22 extends or retracts within the movable hole 28.

[0072] Preferably, a first one-way valve 30 is fixedly installed on the surface of the intake pipe 16, and a second one-way valve 31 is fixedly installed on the surface of the exhaust pipe 32.

[0073] By setting a first one-way valve 30 and a second one-way valve 31, where the first one-way valve 30 is an air intake valve, the air intake pipe 16 can only intake air into the air collection cylinder 15, and the second one-way valve 31 is an exhaust valve, the gas inside the air collection cylinder 15 can only be discharged through the exhaust pipe 32.

[0074] Preferably, the outer surface of the piston 21 is in close contact with the inner wall of the gas collecting cylinder 15, and the material is rubber;

[0075] By setting up piston 21, which is made of rubber, the gas can be compressed and discharged into the gas collection box 17 by moving within the gas collection cylinder 15, thus providing a gas source for subsequent cleaning of the concrete specimen to be tested.

[0076] An experimental method,

[0077] S1: First, place the concrete specimen to be tested in the center of the aluminum alloy bracket 1, and then start the transmission mechanism to move the dial gauge 3 in the testing mechanism closer to the concrete specimen to be tested.

[0078] S2: At the same time, the leveling mechanism will first contact the surface of the concrete specimen. Then, under the influence of pressure, the leveling mechanism will shrink, so as to contact the dial indicator 3 probe, thereby avoiding contact between the dial indicator 3 probe and the recess on the concrete specimen to be tested.

[0079] S3: At the same time, the dust removal mechanism will blow out gas to clean the floating dust generated when the leveling mechanism comes into contact with the concrete specimen, so as to avoid the floating dust affecting the accuracy of the measurement.

[0080] S4: Then, when the value on dial indicator 3 is between five and ten millimeters, record the data on both dial indicators 3 simultaneously.

[0081] S5: After standing for 24 hours, record the data on the two dial gauges again, compare them with the previous records, and calculate the shrinkage rate of the concrete specimen based on the data.

[0082] Working principle: First, the concrete specimen to be tested is placed in the center of the aluminum alloy bracket 1. Then, the transmission mechanism is started and the first helical gear 5 is driven to rotate by the motor 4. Since the first helical gear 5 meshes with the second helical gear 6, the rotation of the first helical gear 5 will drive the second helical gear 6 and the lead screw 7 to rotate. When the lead screw 7 rotates, the external thread on its surface will squeeze the internal thread in the threaded hole 27, so that the moving block 8 can only move slowly along the trajectory of the sliding groove 10, driving the sliding block 9, support block 2, dial indicator 3 and leveling mechanism to the side closer to the concrete specimen to be tested.

[0083] At the same time, as the support block 2 moves the dial indicator 3 closer to the concrete specimen to be tested, it also moves the leveling frame 11 closer to the concrete specimen to be tested. The leveling frame 11 will first contact the surface of the concrete specimen to be tested, and then be compressed by pressure. The spring 12 will contract, and at the same time, the back of the leveling frame 11 will contact the measuring rod of the dial indicator 3. At this time, the data transmitted by the leveling frame 11 is more accurate than the average value of the surface of the concrete specimen to be tested. The data displayed on the dial indicator 3 is also more accurate. As the concrete specimen to be tested contracts, the spring 12 pushes the leveling frame 11 to always contact the surface of the concrete specimen to be tested, and the data on the dial indicator 3 will also change.

[0084] As the moving block 8 moves closer to the concrete specimen to be tested, it drives the connecting block 23, the extrusion rod 22, the piston 21, and the extrusion block 20 to move. At the same time, the piston 21 will extrude the gas into the exhaust pipe 32 and then into the gas collection box 17. After the leveling frame 11 comes into contact with the concrete specimen to be tested and is extruded to the designated position, the touch sensor 24 contacts the touch rod 25. At this time, the solenoid valve is activated, and the gas in the gas collection box 17 will be discharged from the air blowing pipe 19, which blows air onto the contact position between the leveling frame 11 and the concrete specimen to be tested, blowing off the surface dust and achieving the effect of cleaning the surface dust.

[0085] When the data on dial gauge 3 is between five and ten millimeters, record the data on dial gauge 3 again after it has been stationary for twenty-four hours. The shrinkage rate of the concrete specimen can then be calculated.

[0086] 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 concrete shrinkage testing device, comprising an aluminum alloy support (1) and two testing mechanisms, wherein the testing mechanisms are located on top of the aluminum alloy support (1), characterized in that: The testing mechanism includes a support block (2), on one side of which a dial indicator (3) is fixedly installed, with the measuring rod of the dial indicator (3) extending through to one side of the support block (2); a transmission mechanism, which is fixedly mounted on an aluminum alloy bracket (1) and can control the dial indicator (3) to approach the concrete specimen to be tested, thereby detecting the shrinkage of the concrete specimen; a leveling mechanism, which is fixedly mounted on the support block (2), and before the measuring rod of the dial indicator (3) contacts the concrete specimen to be tested, the leveling mechanism will contact the concrete specimen in advance, and the required shrinkage data of the concrete specimen can be obtained when the measuring rod of the dial indicator (3) contacts the leveling mechanism; the transmission mechanism includes a motor (4), which... The motor (4) is fixedly installed at the bottom of the aluminum alloy bracket (1). The output end of the motor (4) is fixedly connected to a first helical gear (5). Both sides of the first helical gear (5) are meshed with second helical gears (6). One side of the second helical gear (6) is fixedly connected to a lead screw (7). The surface of the lead screw (7) is threaded with a moving block (8). The top of the moving block (8) is fixedly connected to a sliding block (9). The top of the sliding block (9) extends through to the top of the aluminum alloy bracket (1) and is fixedly connected to the bottom of the support block (2). The top of the aluminum alloy bracket (1) is provided with a sliding groove (10) that cooperates with the sliding block (9). The leveling mechanism includes a leveling frame (11). Two springs (12) are fixedly connected to one side of the flattening frame (11). One end of the spring (12) is fixedly connected to one side of the support block (2). A guide post (13) is provided inside the spring (12). A guide hole (14) is provided on one side of the flattening frame (11) to cooperate with the guide post (13). A dust removal mechanism is provided on one side of the flattening frame (11) to clean the floating dust generated by the compression when the flattening frame (11) comes into contact with the concrete specimen to be tested. The dust removal mechanism includes an air collection cylinder (15). One end of the air collection cylinder (15) is fixedly connected to one side of the aluminum alloy bracket (1). An air inlet pipe (16) is fixedly connected to the bottom of the air collection cylinder (15). An exhaust pipe (16) is fixedly connected to the top of the air collection cylinder (15). 32), one end of the exhaust pipe (32) is fixedly connected to the air collection box (17), one side of the air collection box (17) is fixedly connected to the support frame (18), the bottom of the support frame (18) is fixedly connected to the top of the support block (2), the bottom of the air collection box (17) is fixedly connected to the air blowing pipe (19) through the solenoid valve, the inside of the air collection cylinder (15) is provided with the extrusion block (20), one side of the extrusion block (20) is fixedly connected to the piston (21), one side of the piston (21) is fixedly connected to the extrusion rod (22), one end of the extrusion rod (22) penetrates into the interior of the aluminum alloy bracket (1) and is fixedly connected to the connecting block (23), the top of the connecting block (23) is fixedly connected to the bottom of the moving block (8);A touch sensor (24) for controlling the solenoid valve is fixedly installed at the bottom of the leveling frame (11). A touch rod (25) is fixedly connected to one side of the support block (2). The touch rod (25) is positioned opposite the touch sensor (24). When the touch sensor (24) contacts the touch rod (25), the solenoid valve is activated, and the gas in the gas collection box (17) is discharged from the air blowing pipe (19) to blow air onto the contact point between the leveling frame (11) and the concrete specimen to be tested, thus blowing off the surface dust.

2. The concrete shrinkage testing device according to claim 1, characterized in that: One end of the lead screw (7) is provided with a bearing (26), and one end of the lead screw (7) is rotatably connected to the inner wall of the aluminum alloy bracket (1) through the bearing (26).

3. The concrete shrinkage testing device according to claim 1, characterized in that: The movable block (8) has a threaded hole (27) on one side, which is used in conjunction with the lead screw (7).

4. The concrete shrinkage testing device according to claim 1, characterized in that: The gas collecting cylinder (15) has a movable hole (28) on one side that is used in conjunction with the extrusion rod (22), and a sealing ring (29) that is used in conjunction with the extrusion rod (22) is fixedly connected to the inner wall of the movable hole (28).

5. The concrete shrinkage testing device according to claim 1, characterized in that: A first one-way valve (30) is fixedly installed on the surface of the intake pipe (16), and a second one-way valve (31) is fixedly installed on the surface of the exhaust pipe (32).

6. The concrete shrinkage testing device according to claim 1, characterized in that: The outer surface of the piston (21) is in close contact with the inner wall of the gas collecting cylinder (15), and the material is rubber.

7. A method for testing concrete shrinkage, based on the concrete shrinkage testing apparatus according to any one of claims 1-6, characterized in that: S1: First, place the concrete specimen to be tested in the center of the aluminum alloy bracket (1), and then start the transmission mechanism so that the dial indicator (3) in the testing mechanism moves closer to the concrete specimen to be tested; S2: At the same time, the leveling mechanism will first contact the surface of the concrete specimen to be tested, and then the leveling mechanism will shrink under the influence of pressure so that it contacts the measuring rod of the dial indicator (3), thereby avoiding the contact between the measuring rod of the dial indicator (3) and the recessed part of the concrete specimen to be tested; S3: At the same time, the dust removal mechanism will blow out gas to clean the floating dust generated by the contact between the leveling mechanism and the concrete specimen to be tested; S4: After that, wait for the value on the dial gauge (3) to be between five and ten millimeters, and record the data on both dial gauges (3); S5: After standing for twenty-four hours, record the data on both dial gauges (3) again, compare with the previous record, and calculate the shrinkage rate of the concrete specimen to be tested through the data.

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