A concrete volume deformation testing device and method

Abstract

This invention proposes a concrete volumetric deformation testing device and method, belonging to the field of concrete testing. It solves the problems of traditional shrinkage testing, which is limited by the insufficient micron-scale resolution and significant noise interference of conventional contact displacement sensors, while non-contact devices with micron-level precision are costly and have poor performance. It includes a displacement input end, one end of which is connected to the concrete specimen, and the other end is connected to the peripheral wall of a first pulley via a first traction component; a second pulley, coaxially connected to the first pulley, with its peripheral wall connected to one end of the second traction component, and the other end of the second traction component connected to the displacement output end after several reversals via a moving pulley group and a fixed pulley group, wherein the diameter of the second pulley is larger than that of the first pulley; a prestressing application component for applying prestress to the second traction component; and a displacement measurement component for measuring the displacement at the displacement output end. It is mainly used for concrete volumetric deformation testing.

Description

Technical Field

[0001] This invention belongs to the field of concrete testing, and in particular relates to a device and method for testing the volume deformation of concrete. Background Technology

[0002] Concrete shrinkage deformation is a key factor inducing structural cracking and reducing durability. Accurate monitoring of concrete shrinkage deformation throughout its entire lifecycle, from initial setting (especially early micro-shrinkage at the micrometer level), is crucial for revealing concrete cracking mechanisms, optimizing mix proportions, evaluating the performance of crack-resistant materials, and developing effective crack prevention measures. As concrete hydration progresses, the main time periods for various shrinkage deformations differ, and the dominant shrinkage types vary at different stages of concrete development. Concrete shrinkage can be categorized into plastic shrinkage, autogenous shrinkage, drying shrinkage, and carbonation shrinkage, among others.

[0003] Drying shrinkage persists throughout the entire setting and hardening process of concrete, continuing even after 28 days and potentially for several years or even decades. Studies have found that drying shrinkage is often a key factor in the formation of cracks in concrete structures, and the causes of drying shrinkage cracks are complex, closely related to construction, design, environmental conditions, and materials, making such problems difficult to solve. Constrained shrinkage occurs when concrete is subjected to external constraints; when the volume changes, tensile stress is generated within the concrete. When this tensile stress exceeds its tensile strength, cracks may appear in the concrete, thereby reducing the load-bearing capacity, durability, and waterproofing of the concrete structure, and shortening its lifespan.

[0004] However, existing shrinkage testing technologies face fundamental challenges: conventional contact displacement sensors (such as strain gauges) and standard length gauges suffer from insufficient resolution at the micrometer scale and significant noise interference, making it difficult to reliably capture critical early shrinkage strain within the first 24 hours of setting; while non-contact devices with sub-micrometer precision (such as laser interferometers) are extremely expensive and sensitive to changes in environmental conditions, making them unsuitable for stable application in conventional laboratories or construction sites. Effective monitoring of micrometer-level shrinkage deformation has become a technical bottleneck restricting research on concrete crack resistance and quality control.

[0005] This invention aims to overcome this bottleneck by innovatively designing a high-magnification, low-loss mechanical displacement amplification mechanism. This mechanism linearly amplifies the micron-level shrinkage / expansion displacement of concrete, which is difficult to capture, by tens to hundreds of times, transforming it into sub-millimeter-level displacement that can be accurately measured by conventional economical sensors. Combined with optimized test fixtures and an automatic data acquisition system, a high-resolution (≤1 micron), wide-range, and highly disturbance-resistant testing method specifically for micron-level shrinkage deformation of concrete is constructed, providing reliable data support for revealing early shrinkage patterns and evaluating the crack resistance of materials. Summary of the Invention

[0006] In view of this, the present invention aims to propose a concrete volume deformation testing device and method to solve the problems of traditional shrinkage testing being limited by the insufficient micron-scale resolution and significant noise interference of conventional contact displacement sensors, while non-contact devices with micron-level precision are costly and have poor performance.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a concrete volume deformation testing device is provided, comprising: The displacement input end is connected to the concrete specimen at one end to deform with the deformation of the concrete specimen, and the other end is connected to the peripheral wall of the first pulley through the first traction component. The second pulley is coaxially connected to the first pulley. The peripheral wall of the second pulley is connected to one end of the second traction member. The other end of the second traction member is connected to the displacement output end after being reversed several times by the movable pulley group and the fixed pulley group. The diameter of the second pulley is larger than that of the first pulley. A prestressing application assembly, connected to the other end of the second traction member, is used to apply prestress to the second traction member; Displacement measurement component, used to measure displacement at the displacement output end.

[0008] Furthermore, the diameter ratio of the first pulley to the second pulley is m, the number of pulley groups in the fixed pulley group and the movable pulley group is n, and the displacement amplification factor of the displacement output end relative to the displacement input end is 2mn.

[0009] Furthermore, the other end of the second traction member is connected to the prestressing application component via the end pulley of the movable pulley block and the steering pulley.

[0010] Furthermore, the prestressing application component is a heavy object with a certain mass.

[0011] Furthermore, the displacement output end is any point of the second traction member after passing through the end of the movable pulley block.

[0012] Furthermore, the displacement measurement component includes a micrometer and an image recognition component. The micrometer is used as a displacement reference for the displacement output end, and the image recognition component is used to identify the micrometer reading.

[0013] Furthermore, both the first and second traction components are traction belts.

[0014] According to another aspect of the present invention, a testing method using a concrete volume deformation testing device as described above is provided, comprising the following steps: Determine the displacement magnification factor for the concrete volume deformation test, and prepare a concrete volume deformation test device based on the displacement magnification factor. Concrete specimens are formed, with one end of the displacement input end fixed to the concrete specimen and the other end connected to the prestressing application component. A micrometer is placed on the displacement output end side. The reading of the micrometer is identified by an image recognition component to obtain the displacement of the displacement output end during the volume deformation of the concrete specimen at different times. The actual displacement value of the volume deformation of the concrete specimen is calculated. At the same time, displacement data is calibrated by acquiring images of the micrometer.

[0015] Furthermore, the types of concrete volumetric deformation tests include drying shrinkage and constrained shrinkage.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This device uses a two-stage amplification process, consisting of a first pulley, a second pulley, a fixed pulley group, and a moving pulley group, to transmit and amplify the micron-level shrinkage displacement of concrete from its initial setting to its hardening stage at a high magnification and linearly. This significantly improves the system resolution to ≤1 micron, completely solving the core technical bottleneck of existing equipment's inaccurate measurement of volume deformation. 2. This device, through displacement amplification, not only achieves wide-range coverage of millimeter-level cumulative deformation but also significantly reduces the reliance on high-precision sensors. Furthermore, the displacement measurement components enable real-time calibration, allowing conventional, economical displacement sensors to perform high-precision measurements. The overall system cost is reduced by more than 60% compared to non-contact solutions such as lasers. It also boasts a robust and reliable structure, strong resistance to environmental vibration interference, and convenient operation, enabling stable operation in ordinary laboratories and engineering sites. This provides a high-precision, low-cost standardized testing tool for research on the early shrinkage mechanism of concrete materials, evaluation of crack-resistant material performance, and construction quality control. 3. This device applies a small amount of prestress to the device through a prestressing application component, giving the overall structure a certain rigidity. When the concrete shrinks, it causes the structure to rotate in the forward direction. When the concrete expands, the prestress causes the structure to rotate in the reverse direction, so that this device can perform both concrete shrinkage and concrete expansion measurements. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a diagram showing the state of the concrete volume deformation testing device of the present invention not connected to the displacement input end and the concrete specimen. Figure 2 This is a state diagram of a specific embodiment of the concrete volume deformation testing device of the present invention. Figure 3 This is a state diagram of a second specific embodiment of the concrete volume deformation testing device of the present invention.

[0018] Displacement input end 1; first traction component 2; first pulley 3; second pulley 4; second traction component 5; fixed pulley block 6; displacement output end 7; movable pulley block 8; prestressing application component 9; concrete specimen 10; steering pulley 11. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0020] It should be noted that the descriptions of "left," "right," "left side," "right side," "upper part," "lower part," "top," and "bottom" in this invention are defined based on the orientation or positional relationships shown in the accompanying drawings. They are merely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the described structure must be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Specific implementation method one: Referring to the accompanying drawings, this embodiment of the invention provides a concrete volume deformation testing device, comprising: The displacement input end 1 is connected at one end to the concrete specimen 10, allowing it to deform in accordance with the deformation of the concrete specimen 10. The other end is connected to the peripheral wall of the first pulley 3 via the first traction member 2. Specifically, the displacement input end 1 is a deformation plate capable of deforming along with the concrete specimen 10. It can be rationally selected according to actual requirements and integrally formed with the concrete specimen 10, with one end of the displacement input end 1 pre-embedded within the concrete specimen 10. The fixing method of the first traction member 2 and the first pulley 3 can be rationally set according to the specific materials of both. After fixing, the first traction member 2 can drive the first pulley 3 to rotate with the displacement of the displacement input end 1.

[0023] The second pulley 4 is coaxially connected to the first pulley 3. The peripheral wall of the second pulley 4 is connected to one end of the second traction member 5. The other end of the second traction member 5 is connected to the displacement output end 7 after several reversals via the movable pulley group 8 and the fixed pulley group 6. The diameter of the second pulley 4 is larger than that of the first pulley 3. The second pulley 4 and the first pulley 3 are fixed using the same shaft, which is connected to a fixed base via bearings. The fixing method of the second pulley 4 and the second traction member 5 can be reasonably set according to the specific materials used. It should be noted that, to ensure measurement accuracy, the first pulley 3, the second pulley 4, the first traction member 2, and the second traction member 5 are all made of easily fitting, high-strength materials that are easy to maintain a taut state and do not easily produce idle stroke. The fixing method of the fixed pulley block 6 and the sliding method of the movable pulley block 8 should be reasonably selected according to the actual situation. For example, the fixing method can be bolt fixing, and the sliding method can be set by the cooperation of slide rail and slider. The sliding method can be reasonably set according to the overall layout of the specific device. Overall, it should be conducive to the experimental process and ensure that the layout will not affect the measurement results.

[0024] The prestressing application component 9 is connected to the other end of the second traction component 5 and is used to apply prestress to the second traction component 5. The prestressing application component 9 is mainly used to provide pre-tightening force so that the displacement of the concrete, whether it expands or shrinks, can be amplified and measured by the displacement measuring component. This allows the device to measure both the expansion and shrinkage processes of concrete, making it widely applicable.

[0025] Displacement measurement component, used to measure displacement at displacement output terminal 7.

[0026] In this embodiment, the diameter ratio of the first pulley 3 to the second pulley 4 is m, the number of pulley groups in the fixed pulley group 6 and the movable pulley group 8 is n, and the displacement amplification factor of the displacement output end 7 relative to the displacement input end 1 is 2mn.

[0027] In this embodiment, the other end of the second traction member 5 is connected to the prestressing application component 9 via the end pulley of the movable pulley block 8 and the steering pulley 11. The steering pulley 11 is designed so that, regardless of the placement of the device, the expansion process can be measured through the cooperation of the steering pulley 11 and the prestressing application component 9. It mainly serves to change the direction of force and assist in applying prestress.

[0028] In this embodiment, the prestressing application component 9 is a heavy object with a certain mass. Alternatively, it can be any other component capable of applying a certain prestress, enabling the overall structure to have a certain rigidity, allowing the concrete shrinkage to drive the structure to rotate in the forward direction, and the prestress to cause the structure to rotate in the reverse direction when the concrete expands. All such components can be used in this application.

[0029] In this embodiment, the displacement output end 7 is any point on the second traction member 5 after passing through the end of the movable pulley block 8. In actual use, selected points that are easy to observe can be marked, and then displacement can be measured in conjunction with a microscope and image recognition components.

[0030] In this embodiment, the displacement measurement component includes a micrometer and an image recognition component. The micrometer serves as a displacement reference for the displacement output terminal 7, and the image recognition component is used to identify the micrometer reading. The image recognition component can utilize existing visual recognition systems; any system capable of accurately recording micrometer readings can be used in this application. The control programs and controllers involved all employ existing technologies.

[0031] In this embodiment, both the first traction member 2 and the second traction member 5 are traction belts. A pulley block linkage method is used to amplify the stroke. The volume deformation of the concrete specimen 10 under test causes the first traction member 2 to shift, which in turn drives the first pulley 3 to rotate. The first pulley 3 and the second pulley 4 rotate concentrically. The displacement is amplified at the first stage. The second pulley 4, through the second traction member 5, drives the fixed pulley block 6 and the movable pulley block 8 to rotate. The displacement is amplified at the second stage and transmitted to the displacement output end. A micrometer is placed on the displacement output end. By recognizing the micrometer reading, the displacement of the output end of the amplification mechanism during the drying shrinkage of the concrete specimen is obtained, and the actual shrinkage value of the concrete volume deformation is calculated. Simultaneously, images of the micrometer are captured and read to calibrate the shrinkage data.

[0032] According to another aspect of the present invention, a testing method using a concrete volume deformation testing device as described above is provided, comprising the following steps: Determine the displacement magnification factor for the concrete volume deformation test, and prepare a concrete volume deformation test device based on the displacement magnification factor. The concrete specimen 10 is formed, with one end of the displacement input end 1 fixed on the concrete specimen 10 and the other end connected to the first traction member 2. A micrometer is placed on the displacement output end 7. The reading of the micrometer is identified by the image recognition component to obtain the displacement of the displacement output end 7 during the volume deformation of the concrete specimen 10 at different times. The actual displacement value of the volume deformation of the concrete specimen 10 is calculated. At the same time, the displacement data is calibrated by acquiring micrometer images.

[0033] like Figure 1 , Figure 2As shown, the first pulley 3 has a diameter of 3mm, the second pulley 4 has a diameter of 9mm, and the pulley group consists of two movable pulleys with a diameter of 3mm and one fixed pulley with a diameter of 3mm, with an overall magnification of 12x. Using optical elements and a camera for measurement enables high-precision displacement measurement. The combination of the lens and camera provides clear images, and the use of a calibration ruler provides accurate dimensions, thereby increasing the accuracy and reliability of the measurement. By capturing the magnified image through the camera, changes in displacement can be observed intuitively. This visual observation facilitates real-time monitoring and analysis of displacement changes. The structural design is simple and suitable for various minute displacement measurement needs. The image ranging method measures the magnified displacement, enabling the displacement testing device to perform image recognition at a low cost and with high accuracy above 10μm, significantly improving testing speed and reducing equipment costs. Specific Implementation Method Two: The difference between this embodiment and specific implementation method one is that: like Figure 3 As shown, the first pulley 3 has a diameter of 2mm, the second pulley 4 has a diameter of 8mm, and the pulley group consists of three movable pulleys with a diameter of 3mm and two pulleys with a diameter of 3mm. The overall magnification is 24 times.

[0035] The sensors, controllers, and control programs mentioned above are all existing technologies and will not be elaborated upon.

[0036] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A concrete volume deformation testing device, characterized in that, include: The displacement input end (1) is connected to the concrete specimen (10) at one end, and is used to deform with the deformation of the concrete specimen (10). The other end is connected to the peripheral wall of the first pulley (3) through the first traction member (2). The second pulley (4) is coaxially connected to the first pulley (3). The peripheral wall of the second pulley (4) is connected to one end of the second traction member (5). The other end of the second traction member (5) is connected to the displacement output end (7) after being switched several times by the moving pulley group (8) and the fixed pulley group (6). The diameter of the second pulley (4) is larger than that of the first pulley (3). The prestressing application component (9) is connected to the other end of the second traction member (5) and is used to apply prestress to the second traction member (5); Displacement measurement component, used to measure displacement at displacement output end (7).

2. The concrete volume deformation testing device according to claim 1, characterized in that: The diameter ratio of the first pulley (3) to the second pulley (4) is m, the number of pulley groups in the fixed pulley group (6) and the movable pulley group (8) is n, and the displacement amplification factor of the displacement output end (7) relative to the displacement input end (1) is 2mn.

3. The concrete volume deformation testing device according to claim 1, characterized in that: The other end of the second traction member (5) is connected to the prestressing application component (9) after passing through the end of the movable pulley group (8) and the steering pulley (11).

4. The concrete volume deformation testing device according to claim 3, characterized in that: The prestressing application component (9) is a heavy object with a certain mass.

5. The concrete volume deformation testing device according to claim 1, characterized in that: The displacement output end (7) is any point of the second traction member (5) after passing through the end of the movable pulley group (8).

6. A concrete volume deformation testing device according to claim 1, 2, 3, 4 or 5, characterized in that: The displacement measurement component includes a micrometer and an image recognition component. The micrometer is used as a displacement reference for the displacement output end (7), and the image recognition component is used to identify the micrometer reading.

7. The concrete volume deformation testing device according to claim 6, characterized in that: Both the first traction component (2) and the second traction component (5) are traction belts.

8. A testing method using a concrete volume deformation testing device as described in claim 1, 2, 3, 4, 5, or 7, characterized in that, Includes the following steps: Determine the displacement magnification factor for the concrete volume deformation test, and prepare a concrete volume deformation test device based on the displacement magnification factor. The concrete specimen (10) is formed, and one end of the displacement input end (1) is fixed on the concrete specimen (10), and the other end is connected to the first traction member (2); A micrometer is placed on the side of the displacement output end (7). The reading of the micrometer is identified by the image recognition component, and the displacement of the displacement output end (7) during the volume deformation of the concrete specimen (10) at different times is obtained. The actual displacement value of the volume deformation of the concrete specimen (10) is calculated. At the same time, the displacement data is calibrated by acquiring micrometer images.

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