A fresh concrete cohesion direct shear test device

Abstract

The application relates to the technical field of concrete cohesion direct shear test, and discloses a fresh concrete cohesion direct shear test device, which comprises a test table, a plurality of rectangular grooves are arranged at equal intervals on the top of the test table, sliding seats are slidably arranged in the plurality of rectangular grooves, the tops of the plurality of sliding seats extend to the outside of the corresponding rectangular grooves respectively, moving molds are fixedly arranged on the tops of the plurality of sliding seats, the top of each moving mold is of an open structure, and an L-shaped frame is fixedly arranged on the top of the test table. The application has the following advantages and effects: the fresh concrete sample can be subjected to the direct shear test under multiple different vertical pressure conditions at the same time, the corresponding shear strength can be measured under the action of different vertical pressures, the operation steps are reduced, the test efficiency and the accuracy of the test results are improved, the direct shear test can be conveniently conducted on the compacted fresh concrete sample, and the accuracy of the test results is further improved.

Description

Technical Field

[0001] This application relates to the field of concrete cohesive direct shear testing technology, and in particular to a cohesive direct shear testing device for fresh concrete. Background Technology

[0002] In construction engineering, the cohesiveness of fresh concrete is one of the key indicators for evaluating its workability and structural quality, directly affecting the pouring, vibration, and molding effects, as well as its final mechanical properties. Accurately testing the cohesiveness of fresh concrete, especially obtaining shear strength under different vertical pressures through direct shear tests, is of great significance for optimizing concrete mix proportions and ensuring construction quality. Currently, existing direct shear testing devices for testing the cohesiveness of fresh concrete have at least the following shortcomings: Firstly, traditional direct shear testing devices are mostly single-group test designs, capable of performing direct shear tests on fresh concrete samples under only one type of vertical pressure at a time. If shear strength data under different vertical pressures are required, multiple tests must be repeated. This not only consumes a lot of time and manpower, but also easily leads to reduced comparability between multiple sets of data due to slight differences in the test environment (such as temperature and humidity) and operating procedures, affecting the accuracy of the test results. Secondly, fresh concrete needs to be fully vibrated after being poured into the mold to ensure compaction; otherwise, internal voids will affect the reliability of the test data. However, the vibration operation of traditional direct shear testing devices often relies on manual hand-held vibrators, which is not only labor-intensive, but also difficult to control the vibration force and uniformity, easily resulting in local under-vibration or over-vibration, which may interfere with subsequent pressurization and shearing operations.

[0003] Therefore, we propose a direct shear test device for the cohesiveness of fresh concrete to solve the above problems. Utility Model Content

[0004] The purpose of this application is to provide a direct shear test device for the cohesiveness of fresh concrete, which can simultaneously conduct direct shear tests on fresh concrete samples under multiple different vertical pressure conditions, measure the corresponding shear strength under different vertical pressures, reduce operation steps, improve test efficiency and accuracy of test results, and facilitate the direct shear test after the fresh concrete samples are vibrated and compacted, further improving the accuracy of test results.

[0005] The above-mentioned technical objective of this application is achieved through the following technical solution: a direct shear test device for the cohesiveness of fresh concrete, comprising a test platform, wherein the top of the test platform has multiple rectangular grooves arranged at equal intervals, each rectangular groove having a sliding seat slidably installed therein, the top of each sliding seat extending outside the corresponding rectangular groove, and a movable mold fixedly installed on the top of each sliding seat, the top of the movable mold being an open structure; an L-shaped frame fixedly installed on the top of the test platform, and multiple crossbeams arranged at equal intervals fixedly installed on one side of the L-shaped frame, each crossbeam having a fixed mold fixedly installed at one end, the top and bottom of the fixed mold being open structures; and multiple fixed molds... Each fixed mold is positioned directly above its corresponding movable mold. The bottom surfaces of multiple fixed molds are respectively attached to the top surfaces of their respective movable molds. Multiple hydraulic cylinders are fixedly installed on the top inner wall of the L-shaped frame. Pressure sensors are fixedly installed on the output shaft ends of each hydraulic cylinder. Pressure plates are fixedly installed at the bottom of each pressure sensor. The pressure plates are slidably installed inside their respective fixed molds. Vibration components are installed above each of the fixed molds. The vibration components are used to vibrate the fresh concrete samples inside the movable and fixed molds. A direct shear thrust component is installed on the test platform. The direct shear thrust component is used to simultaneously push multiple movable molds to move horizontally.

[0006] A further feature of this application is that the fixed mold and the movable mold have the same cross-sectional dimensions, and the four outer walls of the pressure plate are slidably and sealingly fitted with the four inner walls of the fixed mold.

[0007] A further configuration of this application is as follows: the vibration assembly includes an electric telescopic rod, an annular plate, and multiple vibrating rods. The electric telescopic rod is fixedly installed on the top inner wall of the L-shaped frame, the annular plate is fixedly installed on the output shaft end of the electric telescopic rod, and the multiple vibrating rods are all fixedly installed on the bottom of the annular plate. The multiple vibrating rods are distributed in an equally spaced annular pattern around the hydraulic cylinder. The bottom of the pressure plate is provided with multiple equally spaced annularly distributed storage slots, and the top of each of the multiple storage slots is provided with a clearance hole. The bottom ends of the multiple vibrating rods pass through the corresponding clearance holes.

[0008] A further feature of this application is that a sealing scraper ring is fixedly installed inside the clearance hole, and the inner ring wall of the sealing scraper ring slides and seals against the outer wall of the vibrator.

[0009] A further configuration of this application is as follows: the direct shear thrust assembly includes a pad, a second hydraulic cylinder, a connecting beam, multiple support beams, and multiple second pressure sensors. The pad is fixedly installed on the top right side of the test bench, the second hydraulic cylinder is fixedly installed on the top of the pad, the connecting beam is fixedly installed on the output shaft end of the second hydraulic cylinder, the multiple support beams are all fixedly installed on the left side of the connecting beam and arranged at equal intervals, the multiple second pressure sensors are respectively fixedly installed on the left end of the corresponding support beam, and the left side wall of the multiple second pressure sensors is respectively fixedly connected to the right outer wall of the corresponding moving mold.

[0010] A further feature of this application is that a plurality of equidistant limiting baffles are fixedly installed on the top of the test bench, and the plurality of limiting baffles abut against the right outer wall of the corresponding moving mold.

[0011] A further feature of this application is that a horizontal guide rod is fixedly installed inside the rectangular groove, and a slide block is slidably sleeved on the horizontal guide rod.

[0012] A further feature of this application is that a ball bearing is nested at the bottom of the slide block, and the ball bearing makes rolling contact with the bottom inner wall of the rectangular groove.

[0013] A further feature of this application is that rollers are rotatably mounted at the four bottom corners of the movable mold, and the rollers make rolling contact with the top surface of the test bench.

[0014] This application includes at least one of the following beneficial technical effects: 1. This application designs a combination of multiple moving molds and multiple fixed molds, which, together with the synergistic action of multiple hydraulic cylinders, multiple pressure sensors, multiple pressure plates and direct shear thrust components, can simultaneously conduct direct shear tests on fresh concrete samples under various vertical pressure conditions. It can measure the corresponding shear strength under different vertical pressures, reduce operation steps, and improve test efficiency and the accuracy of test results.

[0015] 2. The vibration assembly designed in this application facilitates the compaction of fresh concrete samples before conducting direct shear tests, further reducing manual labor and improving the accuracy of test results. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of this embodiment.

[0017] Figure 2 This is a front view sectional three-dimensional structural schematic diagram of this embodiment.

[0018] Figure 3 yes Figure 2 A magnified structural diagram of part A in the middle.

[0019] Figure 4 This is a schematic diagram of the three-dimensional structure of the pressure plate.

[0020] Figure 5 This is a three-dimensional structural diagram of the vibratory compaction assembly.

[0021] In the diagram, 1. Test bench; 2. Rectangular groove; 3. Slide seat; 4. Moving mold; 5. L-shaped frame; 6. Crossbeam; 7. Fixed mold; 8. Hydraulic cylinder one; 9. Pressure sensor one; 10. Pressure plate; 11. Electric telescopic rod; 12. Ring plate; 13. Vibrator; 14. Storage groove; 15. Clearance hole; 16. Sealing scraper ring; 17. Pad; 18. Hydraulic cylinder two; 19. Connecting beam; 20. Support beam; 21. Pressure sensor two; 22. Limiting baffle; 23. Horizontal guide rod; 24. Ball bearing; 25. Roller. Detailed Implementation

[0022] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] See Figures 1-5 This application provides a direct shear test device for the cohesiveness of fresh concrete, including a test bench 1. The top of the test bench 1 has multiple rectangular grooves 2 arranged at equal intervals. Slide seats 3 are slidably installed in each of the rectangular grooves 2, with the tops of the slide seats 3 extending outside their respective rectangular grooves 2. Movable molds 4 are fixedly installed on the tops of the slide seats 3, with open tops. An L-shaped frame 5 is fixedly installed on the top of the test bench 1. Multiple crossbeams 6 arranged at equal intervals are fixedly installed on one side of the L-shaped frame 5. Fixed molds 7 are fixedly installed at one end of each crossbeam 6, with open tops and bottoms. The fixed molds 7 are located directly above their respective movable molds 4, and their bottom surfaces are in contact with the top surfaces of their respective movable molds 4. Multiple hydraulic cylinders 8 are fixedly installed on the inner top wall of the L-shaped frame 5, with their output shafts fixedly mounted on... The test includes pressure sensors 9, each with a fixed pressure plate 10 at its bottom. These pressure plates 10 are slidably installed within their respective fixed molds 7. The pressure sensors 9 allow for precise and real-time monitoring of the vertical pressure applied to the fresh concrete sample. By combining multiple movable molds 4 with multiple fixed molds 7, direct shear tests under various vertical pressure conditions can be conducted simultaneously on the fresh concrete sample. This allows for the measurement of the corresponding shear strength under different vertical pressures. This multi-group parallel testing design not only reduces the time spent on multiple individual tests and improves testing efficiency, but also allows for the acquisition of multiple sets of data under the same testing environment and operating conditions. This effectively reduces the impact of changes in the external environment or operational differences on the test results, making the comparison of cohesiveness between different samples more intuitive and reliable, and providing richer and more comparable evidence for test analysis results. Figure 1-4As shown, hydraulic cylinder 8 is in a state of extension but not full extension.

[0024] In this embodiment, a vibration assembly is provided above each of the multiple fixed molds 7. The vibration assembly is used to vibrate the fresh concrete samples inside the movable mold 4 and the fixed molds 7. The vibration assembly includes an electric telescopic rod 11, an annular plate 12, and multiple vibrating rods 13. The electric telescopic rod 11 is fixedly installed on the top inner wall of the L-shaped frame 5. The annular plate 12 is fixedly installed on the output shaft end of the electric telescopic rod 11. The multiple vibrating rods 13 are all fixedly installed at the bottom of the annular plate 12, and the multiple vibrating rods 13 are connected by a hydraulic cylinder 8. The center is arranged in an equally spaced ring. The bottom of the pressure plate 10 has multiple equally spaced ring-shaped storage slots 14. The top of each storage slot 14 has a clearance hole 15. The bottom ends of multiple vibrating rods 13 pass through the corresponding clearance holes 15. The electric telescopic rod 11 is used to control the up and down movement of the vibrating rods 13. When it is necessary to vibrate the fresh concrete sample, the vibrating rods 13 can pass through the clearance holes 15 and penetrate into the sample. After vibration is completed, they can be stored in the storage slots 14 without affecting the subsequent pressurization and shearing operations.

[0025] In this embodiment, the fixed mold 7 and the movable mold 4 have the same cross-sectional dimensions. The four outer walls of the pressure plate 10 slide and seal against the four inner walls of the fixed mold 7, ensuring that the fresh concrete sample is subjected to uniform stress during shearing and effectively avoiding stress concentration or leakage caused by mold fit problems.

[0026] In this embodiment, a sealing scraper ring 16 is fixedly installed inside the clearance hole 15. The inner ring wall of the sealing scraper ring 16 slides and seals against the outer wall of the vibrating rod 13. The sealing scraper ring 16 can effectively prevent the fresh concrete sample from overflowing during the movement of the vibrating rod 13, and can scrape off the fresh concrete sample adhering to the vibrating rod 13, ensuring the cleanliness of the device and the smooth progress of the test.

[0027] In this embodiment, a direct shear thrust assembly is provided on the test bench 1. The direct shear thrust assembly is used to simultaneously push multiple moving molds 4 to move horizontally. The direct shear thrust assembly includes a pad 17, a second hydraulic cylinder 18, a connecting beam 19, multiple support beams 20, and multiple second pressure sensors 21. The pad 17 is fixedly installed on the top right side of the test bench 1. The second hydraulic cylinder 18 is fixedly installed on the top of the pad 17. The connecting beam 19 is fixedly installed on the output shaft end of the second hydraulic cylinder 18. The multiple support beams 20 are all fixedly installed on the left side of the connecting beam 19 and are arranged at equal intervals. The multiple second pressure sensors 21 are respectively fixedly installed on the left end of the corresponding support beam 20. The left side wall of the multiple second pressure sensors 21 is fixedly connected to the right outer wall of the corresponding moving mold 4. The setting of the second pressure sensor 21 can accurately monitor the direct shear thrust applied to the freshly mixed concrete sample in real time. Together with the first pressure sensor 9, it detects the vertical pressure value, providing accurate data support for calculating key indicators such as shear stress.

[0028] In this embodiment, a plurality of equally spaced limiting baffles 22 are fixedly installed on the top of the test bench 1. Each limiting baffle 22 abuts against the right outer wall of the corresponding moving mold 4. The limiting baffles 22 are configured to position the rightward movement of the moving mold 4. Figure 1 and Figure 2 As shown, when the movable mold 4 comes into contact with the limiting baffle 22, the movable mold 4 is aligned with the fixed mold 7 above it, so as to facilitate a smooth and accurate direct shear test.

[0029] In this embodiment, a horizontal guide rod 23 is fixedly installed inside the rectangular groove 2, and the slide block 3 is slidably sleeved on the horizontal guide rod 23, which guides the movement direction of the slide block 3 and ensures that the slide block 3 can move smoothly and horizontally in the rectangular groove 2. A ball bearing 24 is nested at the bottom of the slide block 3, and the ball bearing 24 rolls in contact with the inner wall of the bottom of the rectangular groove 2. Rollers 25 are rotatably installed at the four corners of the bottom of the moving mold 4, and the rollers 25 roll in contact with the top surface of the test bench 1. By using the guiding effect of the horizontal guide rod 23 on the slide block 3 and the rolling assistance of the ball bearing 24 and the rollers 25, the frictional resistance of the moving mold 4 during horizontal movement is reduced, making the straight shearing process more stable, avoiding the interference of additional friction on the shearing force measurement, and further improving the accuracy of the test data.

[0030] In this embodiment, a controller is installed on the front side wall of the test bench 1. The controller is equipped with a display screen and multiple control buttons. Hydraulic cylinder 8, pressure sensor 9, electric telescopic rod 11, vibrator 13, hydraulic cylinder 18, and pressure sensor 21 are all electrically connected to the controller. The pressure values ​​monitored by pressure sensor 9 and pressure sensor 21 can be displayed on the display screen for easy viewing by the staff. The multiple control buttons are used to control the power supply and operation of hydraulic cylinder 8, pressure sensor 9, electric telescopic rod 11, vibrator 13, hydraulic cylinder 18, and pressure sensor 21, respectively. The wiring connection method and control method of hydraulic cylinder 8, pressure sensor 9, electric telescopic rod 11, vibrator 13, hydraulic cylinder 18, pressure sensor 21, and the controller are mature technologies in this field and have been fully disclosed and explained. Therefore, they will not be described in detail here.

[0031] Based on the above structure, the working principle of the cohesive direct shear test device for fresh concrete provided in this application is as follows: First, control the hydraulic cylinder 18 to retract and reset. The output shaft of the hydraulic cylinder 18 drives the connecting beam 19, multiple support beams 20, multiple pressure sensors 21, and multiple moving molds 4 to move horizontally to the right to reset until the multiple moving molds 4 slide in the rectangular groove 2 through the slide block 3 and abut against the corresponding limit baffle 22. At this time, the multiple moving molds 4 are precisely aligned with the fixed molds 7 above them. Then, control the hydraulic cylinders 8 to retract and reset, so that the output shaft of the multiple hydraulic cylinders 8 drives the corresponding pressure plates 10 to rise and return to their original positions. At this time, the multiple pressure plates 10 move out of the corresponding fixed molds 7. Then, put an appropriate amount of the same fresh concrete sample into the integral cavity composed of multiple sets of moving molds 4 and fixed molds 7. Next, multiple hydraulic cylinders 8 are extended and operated, causing multiple pressure plates 10 to move down to the corresponding fixed mold 7. Then, the operation of multiple hydraulic cylinders 8 is stopped. Then, multiple electric telescopic rods 11 are extended and operated. The output shaft of the electric telescopic rods 11 drives the annular plate 12 to move down, so that multiple vibrating rods 13 pass through the clearance hole 15 and penetrate into the interior of the fresh concrete sample. The vibrating rods 13 are started to vibrate the sample to make the fresh concrete sample dense. After the vibration is completed, the electric telescopic rods 11 are retracted and reset, driving the vibrating rods 13 to move up and finally be stored in the storage groove 14. During this process, the sealing scraper ring 16 scrapes off the concrete adhering to the vibrating rods 13 to keep the device clean. After vibration, multiple hydraulic cylinders 8 are extended again, pushing the corresponding pressure sensors 9 and pressure plates 10 downwards. Pressure plates 10 slide within the fixed mold 7, applying vertical pressure to the concrete sample. Pressure sensors 9 monitor the applied vertical pressure value in real time and transmit the data to the controller. Operators can view the pressure data on the controller's display screen. The extension of multiple hydraulic cylinders 8 is adjusted according to test requirements to achieve the desired pressure, ensuring that the pressure values ​​applied to the corresponding fresh concrete samples by the multiple pressure plates 10 are different. Then, hydraulic cylinder 18 is extended, its output shaft extending to push the connecting beam 19 to the left. The connecting beam 19, through the support beam 20 and pressure sensor 21, drives multiple moving parts... Simultaneously, mold 4 moves to the left, and multiple moving molds 4 are subjected to horizontal thrust, causing relative displacement with their corresponding fixed molds 7, thus applying horizontal shear force to the concrete sample. At this time, through multiple pressure sensors 21, the direct shear thrust value can be monitored in real time and the data can be transmitted to the controller. The staff can observe in real time through the display screen. When each fresh concrete sample experiences shear failure, the vertical pressure value monitored by the corresponding pressure sensor 9 and the direct shear thrust value monitored by the pressure sensor 21 are recorded respectively. Combined with parameters such as the cross-sectional dimensions of the mold, the shear strength of the concrete sample under the vertical pressure can be calculated according to Coulomb's law and existing formulas, thereby accurately analyzing the cohesiveness of the fresh concrete. After the test is completed, first control the hydraulic cylinder 18 to retract and reset, then control the multiple hydraulic cylinders 8 to retract and reset, so that each fresh concrete sample can be taken out in sequence, and the inside of the multiple moving molds 4 and multiple fixed molds 7 can be cleaned, so that it can be used for the next test.

Claims

1. A direct shear test apparatus for the cohesiveness of freshly mixed concrete, characterized in that, The test bench (1) has multiple rectangular slots (2) arranged at equal intervals on its top. Each rectangular slot (2) has a sliding block (3) slidably installed inside it. The tops of the sliding blocks (3) extend outside their respective rectangular slots (2). Each sliding block (3) has a fixed movable mold (4) fixedly installed on its top. The top of the movable mold (4) is open. An L-shaped frame (5) is fixedly installed on the top of the test bench (1). Multiple horizontal beams (6) arranged at equal intervals are fixedly installed on one side of the L-shaped frame (5). A fixed mold (7) is fixedly installed at one end of each horizontal beam (6). The top and bottom of the fixed mold (7) are open. Each fixed mold (7) is located directly above its corresponding movable mold (4). The bottom surfaces of the multiple fixed molds (7) are respectively attached to the top surfaces of the corresponding movable molds (4). Multiple hydraulic cylinders (8) are fixedly installed on the top inner wall of the L-shaped frame (5). Pressure sensors (9) are fixedly installed at the output shaft ends of the multiple hydraulic cylinders (8). Pressure plates (10) are fixedly installed at the bottom of the multiple pressure sensors (9). The multiple pressure plates (10) are respectively slidably installed in the corresponding fixed molds (7). Vibration components are provided above the multiple fixed molds (7). The vibration components are used to vibrate the fresh concrete samples in the movable molds (4) and fixed molds (7). A direct shear thrust component is provided on the test bench (1). The direct shear thrust component is used to simultaneously push the multiple movable molds (4) to move horizontally.

2. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 1, characterized in that: The fixed mold (7) and the movable mold (4) have the same cross-sectional dimensions, and the four outer walls of the pressure plate (10) are slidably sealed to the four inner walls of the fixed mold (7).

3. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 1, characterized in that: The vibrating assembly includes an electric telescopic rod (11), an annular plate (12), and multiple vibrating rods (13). The electric telescopic rod (11) is fixedly installed on the top inner wall of the L-shaped frame (5). The annular plate (12) is fixedly installed on the output shaft end of the electric telescopic rod (11). The multiple vibrating rods (13) are all fixedly installed on the bottom of the annular plate (12), and the multiple vibrating rods (13) are evenly spaced in a ring around the hydraulic cylinder (8). The bottom of the pressure plate (10) is provided with multiple equally spaced ring-shaped storage slots (14). The top of the multiple storage slots (14) is provided with clearance holes (15). The bottom ends of the multiple vibrating rods (13) pass through the corresponding clearance holes (15).

4. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 3, characterized in that: A sealing scraper ring (16) is fixedly installed inside the clearance hole (15), and the inner ring wall of the sealing scraper ring (16) slides and seals against the outer wall of the vibrating rod (13).

5. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 1, characterized in that: The direct shear thrust assembly includes a pad (17), a second hydraulic cylinder (18), a connecting beam (19), multiple support beams (20), and multiple second pressure sensors (21). The pad (17) is fixedly installed on the top right side of the test bench (1). The second hydraulic cylinder (18) is fixedly installed on the top of the pad (17). The connecting beam (19) is fixedly installed on the output shaft end of the second hydraulic cylinder (18). The multiple support beams (20) are all fixedly installed on the left side of the connecting beam (19) and arranged at equal intervals. The multiple second pressure sensors (21) are respectively fixedly installed on the left end of the corresponding support beam (20). The left side wall of the multiple second pressure sensors (21) is respectively fixedly connected to the right outer wall of the corresponding moving mold (4).

6. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 5, characterized in that: The test bench (1) is fixedly installed with multiple limiting baffles (22) that are evenly spaced on the top. The multiple limiting baffles (22) abut against the right outer wall of the corresponding moving mold (4).

7. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 5, characterized in that: A horizontal guide rod (23) is fixedly installed inside the rectangular groove (2), and the slide block (3) is slidably sleeved on the horizontal guide rod (23).

8. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 5, characterized in that: The bottom of the slide (3) is nested with a ball (24), which rolls in contact with the bottom inner wall of the rectangular groove (2).

9. The direct shear test apparatus for the cohesiveness of freshly mixed concrete according to claim 5, characterized in that: The four bottom corners of the movable mold (4) are each equipped with a roller (25), which rolls in contact with the top surface of the test bench (1).

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