A tester for concrete shrinkage and expansion performance
By using a lifting and horizontal movement mechanism to adjust the position of the dial gauge in the concrete shrinkage and expansion performance tester, and by reducing friction and temperature and humidity differences through ball bearings and air supply mechanism, the problem of inaccurate measurement in existing devices has been solved, and accurate measurement of concrete test blocks has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GANSU HENGTONG BRIDGE ENG CO LTD
- Filing Date
- 2025-07-03
- Publication Date
- 2026-06-09
Smart Images
Figure CN224341532U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of cement concrete testing technology, specifically relating to a tester for the shrinkage and expansion properties of concrete. Background Technology
[0002] The shrinkage and expansion properties of concrete have a significant impact on the durability of engineering structures. Because concrete shrinks or expands during hydration, drying, and changes in temperature and humidity, failure to accurately monitor these changes can lead to cracking, deformation, and even structural failure. Therefore, precise testing of concrete shrinkage and expansion deformation is crucial for optimizing concrete mix proportions, improving construction techniques, and enhancing project quality.
[0003] Currently, most concrete shrinkage and expansion testing devices can only test specimens of fixed sizes and cannot adapt to concrete specimens of different sizes. Furthermore, the concrete specimens are in direct contact with the testing platform, and the large sliding friction will produce large measurement errors.
[0004] Furthermore, existing concrete shrinkage and expansion testing devices typically only have a dial indicator on one side of the specimen to measure the deformation at a single point. However, when the specimen is placed horizontally, due to the support method and the distribution of internal stress in the material, uneven shrinkage and expansion deformation may occur in different parts. Relying solely on a dial indicator on one side cannot fully reflect the overall deformation of the specimen, leading to deviations in the test data and affecting the accuracy and reliability of the measurement.
[0005] Meanwhile, existing concrete shrinkage and expansion testing devices, when measuring concrete shrinkage and expansion, do not allow air to circulate at the bottom of the concrete, which can easily cause abnormal local air temperature and humidity, leading to abnormal shrinkage and expansion deformation at the bottom of the concrete and affecting measurement accuracy. Utility Model Content
[0006] The purpose of this invention is to provide a tester for the shrinkage and expansion properties of concrete, so as to solve the problem that existing concrete shrinkage and expansion test devices cannot fully reflect the overall deformation of the test block and that abnormal shrinkage and expansion deformation at the bottom of the concrete affects the measurement accuracy and reliability.
[0007] To address the aforementioned problems, this invention proposes a tester for the shrinkage and expansion properties of concrete. The technical solution adopted is as follows:
[0008] A tester for the shrinkage and expansion properties of concrete includes an installation platform with an installation opening at the center of its surface. A first lifting mechanism is installed on one side of the platform, and a first dial indicator is mounted on the first lifting mechanism to allow for vertical movement of the dial indicator. A horizontal moving mechanism is installed on the other side of the platform, capable of moving along its length. This horizontal moving mechanism adjusts the distance between the concrete specimen and the first lifting mechanism according to its length. A second lifting mechanism is mounted on the horizontal moving mechanism, and a second dial indicator is mounted on the second lifting mechanism to allow for vertical movement of the second dial indicator. Two rows of crossbeams are arranged along the length of the installation opening. Multiple grooves are provided on the crossbeams, and ball bearings are placed in the grooves, with concrete specimens placed on the ball bearings. The tester also includes an air supply mechanism. Ventilation ducts are formed inside the two rows of crossbeams along their length, and multiple air outlets are formed on their opposite sides, connecting the ventilation ducts to the multiple air outlets. The air supply mechanism is connected to one end of the ventilation ducts to deliver air through the ventilation ducts to the multiple air outlets.
[0009] Furthermore, the first lifting mechanism includes a lifting rod, and the first dial indicator is installed at the top of the lifting rod; a second groove is provided at the upper left end of the mounting platform, and the lifting rod is installed in the second groove so as to move up and down; a first limiting screw is provided at the left side of the mounting platform, and the first limiting screw is used to limit and fix the lifting rod.
[0010] Furthermore, the horizontal moving mechanism includes a movable seat, and the two rows of crossbeams and the front and rear sides of the mounting platform form two first sliding grooves, which are opened along the length direction of the mounting platform. The movable seat is movably installed in the first sliding grooves so that it can move along the length direction of the mounting platform.
[0011] Furthermore, a second sliding groove is provided on the opposite sides of the front and rear sides of the installation platform. The second sliding groove is opened along the length of the installation platform, and a second limiting screw is provided in the second sliding groove. The second limiting screw is used to limit and fix the movable seat.
[0012] Furthermore, a third sliding groove is provided in the middle of the movable seat along its height direction. A sleeve is provided in the third sliding groove and slides up and down along the third sliding groove. The sleeve is arranged in a direction perpendicular to the third sliding groove. A second dial indicator is provided at the end of the sleeve away from the first dial indicator. The sleeve slides up and down along the third sliding groove, thereby driving the second dial indicator to move up and down.
[0013] Furthermore, a fourth slide groove is provided at the upper end of the movable seat. The fourth slide groove is connected to the third slide groove. A slider and a lifting screw are provided in the fourth slide groove. A handle is fixedly connected above the lifting screw, and the lifting screw is inserted into the slider along the height direction. The sleeve is inserted into the slider along the horizontal direction. The lifting screw drives the slider to move up and down, and at the same time drives the sleeve to move down, thereby driving the second dial indicator to move up and down.
[0014] Furthermore, the multiple grooves on the crossbeam are equally spaced along the length of the crossbeam, and the multiple grooves on the two crossbeams are symmetrically arranged, with the multiple air outlets corresponding one-to-one with the multiple grooves.
[0015] Furthermore, the air supply mechanism includes a connecting hose and a miniature blower, the connecting hose and the miniature blower are connected, and two air inlets are opened on the right side of the mounting platform, the connecting hose is connected to one end of the ventilation duct through the air inlets.
[0016] Furthermore, the two rows of crossbeams are arranged symmetrically with respect to the center of the mounting platform, so that the two first sliding grooves are arranged symmetrically.
[0017] Furthermore, the number and placement of the balls can be adjusted according to the length of the concrete test block.
[0018] Beneficial Effects: This utility model is an improved utility model. It achieves the vertical movement of the first dial indicator by setting a first lifting mechanism, and the horizontal movement mechanism and its second lifting mechanism achieve the horizontal and vertical movement of the second dial indicator. Based on the length and thickness of the concrete specimen, the dial indicators on both sides of the testing instrument can be moved to appropriate positions on both sides of the concrete specimen. When the concrete specimen shrinks or expands, the corresponding changes can be read on the first and second dial indicators, enabling simultaneous monitoring of the deformation on both sides of the concrete specimen, thus more accurately reflecting the overall shrinkage and expansion characteristics of the specimen. Simultaneously, multiple ball bearings are installed on the crossbeam of the installation platform. The concrete specimen is placed on these ball bearings, transforming the sliding friction between the concrete specimen and the contact surface into rolling friction, which greatly reduces the coefficient of friction, thereby reducing the interference of frictional force on the shrinkage or expansion of the concrete specimen and reducing experimental measurement errors. This invention provides a concrete shrinkage and expansion performance tester that effectively overcomes the limitations of unilateral measurement. It can adapt to concrete specimens of different lengths and thicknesses, significantly reducing test errors and effectively improving the testing accuracy of concrete specimen shrinkage and expansion. This results in a more precise reflection of the overall shrinkage and expansion characteristics of the concrete specimen, making the test data more scientific and valuable for engineering applications. Furthermore, this invention incorporates an air supply mechanism that slowly delivers air, ensuring that the temperature and humidity of the air at the bottom of the concrete specimen remain consistent with the surrounding environment, further reducing test errors.
[0019] The first lifting mechanism includes a lifting rod, and a first dial indicator is mounted on the top of the lifting rod. A first groove is provided at the upper left end of the mounting platform, and the lifting rod is movably mounted in the first groove. A first limiting screw is provided on the left side of the mounting platform to limit and fix the lifting rod. This structure allows the first dial indicator on the left side to be fixed in a suitable position according to the thickness of the concrete test block.
[0020] The installation platform has second sliding grooves on its front and rear sides, extending along its length. Second limiting screws are installed within these grooves to secure the movable seat. This structure fixes the movable seat in a suitable position based on the length of the concrete test block.
[0021] A third sliding groove is formed in the middle of the movable base along its height direction. A sleeve is installed in the third sliding groove, sliding up and down along it. The sleeve is positioned perpendicular to the third sliding groove. A second dial indicator is installed on the end of the sleeve away from the first dial indicator. The sleeve slides up and down along the third sliding groove, thereby moving the second dial indicator up and down. The thickness of the concrete test block determines the appropriate position for the second dial indicator. Attached Figure Description
[0022] Figure 1 This is a three-dimensional structural schematic diagram of the concrete shrinkage and expansion performance tester of this utility model;
[0023] Figure 2 This is a top view of the concrete shrinkage and expansion performance tester of this utility model;
[0024] In the diagram, 1. Installation platform; 2. Lifting rod; 3. First mounting box; 4. First dial indicator; 5. Moving base; 6. First slide groove; 7. Crossbeam; 8. Groove II; 9. First limit screw; 10. Groove I; 11. Ball bearing; 12. Second slide groove; 13. Second limit screw; 14. Third slide groove; 15. Sleeve; 16. Second mounting box; 17. Second dial indicator; 18. Fourth slide groove; 19. Slider; 20. Lifting screw; 21. Handle; 22. Air inlet; 23. Hose; 24. Miniature blower; 25. Ventilation duct; 26. Air outlet. Detailed Implementation
[0025] As cited in the background art, existing concrete shrinkage and expansion testing devices cannot fully reflect the overall deformation of the test block, thus affecting the measurement accuracy and reliability. Therefore, this utility model provides a tester for the shrinkage and expansion properties of concrete, including an installation platform with an installation opening in the center of its surface. A first lifting mechanism is installed on one side of the installation platform, and a first dial indicator is installed on the first lifting mechanism to move the dial indicator up and down, thereby moving the dial indicator on the left side of the tester to a suitable position on both sides of the concrete specimen according to the length and thickness of the concrete specimen. A horizontal moving mechanism is installed on the other side of the installation platform, moving along the length of the installation platform. The horizontal moving mechanism is used to adjust the distance between the concrete specimen and the first lifting mechanism according to the length of the concrete specimen. A second lifting mechanism is installed on the horizontal moving mechanism, and a second dial indicator is installed on the second lifting mechanism to move the dial indicator on the right side of the tester to a suitable position on both sides of the concrete specimen according to the length and thickness of the concrete specimen. Two rows of crossbeams are arranged along the length of the installation opening, and multiple grooves are provided on the crossbeams. Rolling balls are placed in the grooves, and concrete specimens are placed on the rolling balls, which transforms the sliding friction between the concrete specimen and the contact surface into rolling friction, greatly reducing the coefficient of friction and reducing experimental measurement errors. The testing instrument also includes an air supply mechanism. Ventilation ducts are formed along the length of the two rows of crossbeams, and multiple air outlets are located on their opposite sides, connecting the ventilation ducts to the outlets. The air supply mechanism is connected to one end of the ventilation ducts to deliver air to the outlets, ensuring that the temperature and humidity of the air at the bottom of the concrete are consistent with the surrounding environment, thus reducing test errors. This invention effectively overcomes the limitations of single-sided measurement, adapts to concrete specimens of different lengths and thicknesses, significantly reduces test errors, and effectively improves the accuracy of concrete specimen shrinkage and expansion testing. It more accurately reflects the overall shrinkage and expansion characteristics of the concrete specimen, making the test data more scientific and valuable for engineering applications.
[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0028] In the description of the embodiments of this utility model, it should be noted that if terms such as "upper," "lower," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, they are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the utility model. In addition, terms such as "one" and "two" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0029] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0030] Specific embodiment 1 of the concrete shrinkage and expansion performance tester of this utility model:
[0031] In this embodiment, as Figure 1 and Figure 2As shown, the concrete shrinkage and expansion performance tester includes an installation platform 1 with an installation opening in the center of its surface. A first lifting mechanism is installed on one side of the installation platform 1, and a first dial indicator 4 is installed on the first lifting mechanism to allow the first dial indicator 4 to move up and down. The first dial indicator 4 is used to measure the shrinkage or expansion data on the left side of the concrete test block. A horizontal moving mechanism is installed on the other side of the installation platform 1, which moves along the length of the installation platform 1. The horizontal moving mechanism is used to adjust the distance between the concrete test block and the first lifting mechanism according to the length of the concrete test block. A second lifting mechanism is installed on the horizontal moving mechanism, and a second dial indicator 17 is installed on the second lifting mechanism to allow the second dial indicator 17 to move up and down. The second dial indicator 17 is used to measure the shrinkage or expansion data on the right side of the concrete test block. Two rows of crossbeams 7 are arranged along the length of the installation opening. Multiple grooves 10 are provided on the crossbeams 7, and ball bearings 11 are placed in the grooves 10. Concrete test blocks are placed on the ball bearings 11. In use, the first dial gauge 4 and the second dial gauge 17 are adjusted to appropriate positions according to the thickness of the concrete specimen, and the horizontal movement mechanism is adjusted to appropriate positions according to the length of the concrete specimen, so as to realize synchronous monitoring of the deformation on both sides of the concrete specimen. The tester also includes an air supply mechanism. Ventilation ducts 25 are opened inside the two rows of crossbeams 7 along their length direction, and multiple air outlets 26 are opened on their opposite sides, so that the ventilation ducts 25 are connected to the multiple air outlets 26. The air supply mechanism is connected to one end of the ventilation ducts 25 to deliver air through the ventilation ducts 25 to the multiple air outlets 26. Among them, multiple grooves 10 on the crossbeams 7 are equally spaced along the length direction of the crossbeams 7, and the multiple grooves 10 on the two crossbeams 7 are symmetrically arranged. The multiple air outlets 26 are corresponding to the multiple grooves 10. The number and placement position of the ball bearings 11 are adjustable according to the length of the concrete specimen.
[0032] Specifically, the first lifting mechanism includes a lifting rod 2, and a first dial indicator 4 is installed at the top of the lifting rod 2. A first mounting box 3 is fixedly installed at the top of the lifting rod 2, and the first dial indicator 4 is inserted into the first mounting box 3. A groove 2 8 is provided at the upper left side of the mounting platform 1, and the lifting rod 2 is installed in the groove 2 8, which can move up and down. A first limiting screw 9 is provided at the left side of the mounting platform 1. The first limiting screw 9 is used to limit and fix the lifting rod 2. When the lifting rod 2 adjusts the first dial indicator 4 to a suitable position, the first limiting screw 9 fixes the lifting rod 2 in a specific position, which can fix the first dial indicator 4 at a specific height, thereby adapting to concrete test blocks of different thicknesses.
[0033] In other embodiments, the plurality of grooves 10 on the multi-beam 7 may be arranged at unequal intervals along the length of the beam 7.
[0034] In other embodiments, the plurality of grooves 10 on the two crossbeams 7 may be arranged asymmetrically.
[0035] In other embodiments, the multiple air outlets 26 and the multiple recesses 10 may not be configured in a one-to-one correspondence.
[0036] Specific embodiment 2 of the concrete shrinkage and expansion performance tester of this utility model:
[0037] Based on the above-described technical concept of this utility model, or based on the specific embodiments of this utility model described above, another embodiment is provided below.
[0038] In this embodiment, as Figure 1 and Figure 2 As shown, the horizontal moving mechanism includes a movable seat 5, two rows of crossbeams 7 forming two first sliding grooves 6 with the front and rear sides of the mounting platform 1, and the two first sliding grooves 6 are opened along the length direction of the mounting platform 1. The movable seat 5 is movably installed in the first sliding grooves 6, allowing it to move along the length direction of the mounting platform 1. The two rows of crossbeams 7 are symmetrically arranged with respect to the center of the mounting platform 1, so that the two first sliding grooves 6 are symmetrically arranged.
[0039] The mounting platform 1 has a second sliding groove 12 on the opposite sides of the front and rear sides. The second sliding groove 12 is opened along the length of the mounting platform 1. A second limiting screw 13 is provided in the second sliding groove 12. The second limiting screw 13 is used to limit and fix the movable seat 5, so as to accommodate concrete test blocks of different lengths.
[0040] In this embodiment, a third slide groove 14 is provided in the middle of the movable seat 5 along its height direction. A sleeve 15 is provided in the third slide groove 14 and slides up and down along the third slide groove 14. The sleeve 15 is arranged in a direction perpendicular to the third slide groove 14. A second micrometer 17 is provided on the end of the sleeve 15 away from the first micrometer 4. The sleeve 15 slides up and down along the third slide groove 14, thereby driving the second micrometer 17 to move up and down. A second mounting box 16 is installed on the end of the sleeve 15 away from the first micrometer 4, and the second micrometer 17 is installed in the second mounting box 16. A fourth slide groove 18 is provided at the upper end of the movable seat 5, which communicates with the third slide groove 14. A slider 19 and a lifting screw 20 are provided within the fourth slide groove 18. A handle 21 is fixedly connected above the lifting screw 20, and the lifting screw 20 is inserted into the slider 19 along the height direction. A sleeve 15 is inserted into the slider 19 along the horizontal direction. The lifting screw 20 drives the slider 19 to move up and down, simultaneously driving the sleeve 15 to move down, thereby driving the second dial indicator 17 to move up and down. Specifically, rotating the handle 21 can rotate the lifting screw 20, thereby driving the slider 19 to slide up and down, and moving the second dial indicator 17 to a specific height, thus adapting to concrete test blocks of different thicknesses.
[0041] Specific embodiment 3 of the concrete shrinkage and expansion performance tester of this utility model:
[0042] Based on the above-described technical concept of this utility model, or based on the specific embodiments of this utility model described above, another embodiment is provided below.
[0043] In this embodiment, as Figure 1 and Figure 2 As shown, the air supply mechanism includes a connecting hose 23 and a miniature blower 24. The connecting hose 23 and the miniature blower 24 are connected. Two air inlets 22 are opened on the right side of the installation platform 1. The connecting hose 23 is connected to one end of the ventilation duct 25 through the air inlets 22. That is, there are two connecting hoses 23, which are connected to one end of the ventilation duct 25 through the two air inlets 22 respectively, so that the temperature and humidity of the air at the bottom of the concrete are consistent with the surrounding environment, reducing test errors.
[0044] The working process of the concrete shrinkage and expansion performance tester of this utility model is as follows:
[0045] In use, under specific curing conditions, the formed concrete specimen is placed on the ball bearing 11. The horizontal position of the moving seat 5 is adjusted according to the length of the concrete specimen, and the height of the first dial gauge 4 and the second dial gauge 17 is adjusted according to the thickness of the concrete specimen, so that they are precisely aligned with the top rods on both sides of the concrete specimen. Then, the tester and the concrete specimen are kept stationary, and the data of the dial gauges on both sides are read at a specific age. The shrinkage and expansion data are then calculated separately, and the sum of the shrinkage and expansion data of the dial gauges on both sides is the test data.
[0046] This utility model discloses a tester for the shrinkage and expansion properties of concrete. Through reasonable design, it can adapt to concrete test blocks of different sizes, significantly reduce test errors, and more accurately reflect the overall shrinkage and expansion characteristics of the test block, thereby improving test accuracy and having good engineering application value.
[0047] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. The patent protection scope of the present utility model shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present utility model shall also be included in the protection scope of the present utility model.
Claims
1. An instrument for testing the shrinkage and expansion properties of concrete, characterized in that, The system includes an installation platform (1), with an installation opening in the center of its surface. A first lifting mechanism is installed on one side of the installation platform (1), and a first dial indicator (4) is installed on the first lifting mechanism to enable the dial indicator (4) to move up and down. A horizontal moving mechanism that can move along the length of the installation platform (1) is installed on the other side of the installation platform (1). The horizontal moving mechanism is used to adjust the distance between the concrete test block and the first lifting mechanism according to the length of the concrete test block. A second lifting mechanism is installed on the horizontal moving mechanism, and a second dial indicator (17) is installed on the second lifting mechanism to enable the second dial indicator (17) to move up and down. The device moves downward; two rows of crossbeams (7) are arranged along the length of the mounting port, and multiple grooves (10) are provided on the crossbeams (7). Ball bearings (11) are placed in the grooves (10), and concrete test blocks are placed on the ball bearings (11); the tester also includes an air supply mechanism. Ventilation ducts (25) are opened inside the two rows of crossbeams (7) along their length, and multiple air outlets (26) are opened on their opposite sides, so that the ventilation ducts (25) are connected to the multiple air outlets (26). The air supply mechanism is connected to one end of the ventilation ducts (25) and is used to transport air through the ventilation ducts (25) to the multiple air outlets (26).
2. The tester for the shrinkage and expansion properties of concrete according to claim 1, characterized in that, The first lifting mechanism includes a lifting rod (2), and the first dial indicator (4) is installed on the top of the lifting rod (2); a groove 2 (8) is provided at the upper left end of the mounting platform (1), and the lifting rod (2) is installed in the groove 2 (8) in a way that can move up and down; a first limiting screw (9) is provided at the left side of the mounting platform (1), and the first limiting screw (9) is used to limit and fix the lifting rod (2).
3. The tester for the shrinkage and expansion properties of concrete according to claim 1, characterized in that, The horizontal moving mechanism includes a movable seat (5), and the two rows of crossbeams (7) and the front and rear sides of the mounting platform (1) form two first sliding grooves (6), and the two first sliding grooves (6) are opened along the length direction of the mounting platform (1). The movable seat (5) is movably installed in the first sliding groove (6) so that it moves along the length direction of the mounting platform (1).
4. The tester for the shrinkage and expansion properties of concrete according to claim 3, characterized in that, The installation platform (1) has a second slide groove (12) on the opposite sides of the front and rear sides. The second slide groove (12) is opened along the length of the installation platform (1). A second limiting screw (13) is provided in the second slide groove (12). The second limiting screw (13) is used to limit and fix the movable seat (5).
5. The tester for the shrinkage and expansion properties of concrete according to claim 4, characterized in that, The moving base (5) has a third slide groove (14) in the middle along its height direction. A sleeve (15) is provided in the third slide groove (14) and slides up and down along the third slide groove (14). The sleeve (15) is arranged in a direction perpendicular to the third slide groove (14). A second micrometer (17) is provided at the end of the sleeve (15) away from the first micrometer (4). The sleeve (15) slides up and down along the third slide groove (14), thereby driving the second micrometer (17) to move up and down.
6. The tester for the shrinkage and expansion properties of concrete according to claim 5, characterized in that, A fourth slide groove (18) is provided at the upper end of the movable seat (5). The fourth slide groove (18) is connected to the third slide groove (14). A slider (19) and a lifting screw (20) are provided in the fourth slide groove (18). A handle (21) is fixedly connected above the lifting screw (20). The lifting screw (20) is inserted into the slider (19) along the height direction. The sleeve (15) is inserted into the slider (19) along the horizontal direction. The lifting screw (20) drives the slider (19) to move up and down, and at the same time drives the sleeve (15) to move down, thereby driving the second dial indicator (17) to move up and down.
7. The tester for the shrinkage and expansion properties of concrete according to claim 1, characterized in that, The multiple grooves (10) on the crossbeam (7) are equally spaced along the length of the crossbeam (7), and the multiple grooves (10) on the two crossbeams (7) are symmetrically arranged. The multiple air outlets (26) are arranged in a one-to-one correspondence with the multiple grooves (10).
8. The tester for the shrinkage and expansion properties of concrete according to claim 1, characterized in that, The air supply mechanism includes a connecting hose (23) and a miniature blower (24). The connecting hose (23) and the miniature blower (24) are connected. Two air inlets (22) are opened on the right side of the mounting platform (1). The connecting hose (23) is connected to one end of the ventilation duct (25) through the air inlets (22).
9. The tester for the shrinkage and expansion properties of concrete according to claim 3, characterized in that, The two rows of crossbeams (7) are arranged symmetrically with respect to the center of the installation platform (1), so that the two first slides (6) are arranged symmetrically.
10. The tester for the shrinkage and expansion properties of concrete according to claim 1, characterized in that, The number and placement of the ball bearings (11) can be adjusted according to the length of the concrete test block.