Concrete permeability test mould

Abstract

The utility model discloses a kind of concrete water permeability test mould, mould includes bottom plate, water storage cylinder, hopper, water tank and water receiving tank, bottom plate is fixed water storage cylinder by clamping column, water storage cylinder side wall is equipped with bracing screw rod and L-shaped support to stabilize support test piece;The inner wall of the lower part straight section of hopper is equipped with variable-diameter annular rubber ring, the inner diameter of rubber ring gradually increases from bottom to top and bottom surface inner diameter is less than test piece diameter, can self-adapting fill test piece and hopper gap, strengthen sealing and position test piece;Water storage cylinder side wall is equipped with overflow pipe, can discharge excess moisture to maintain constant water level in cylinder, cooperate with the electromagnetic valve of water tank, liquid level sensor and control module of water receiving tank, realize water supply automation and water quantity accurate measurement.The utility model uses the above structure, can ensure that effective water area is stable, avoid water leakage or eddy current interference, improve the accuracy and repeatability of water permeability coefficient detection, and adapt to different specifications test piece, convenient operation, applicable to building, municipal field concrete water permeability performance detection.

Description

Technical Field

[0001] This utility model relates to the field of concrete permeability testing technology, specifically a concrete permeability testing mold. Background Technology

[0002] In construction engineering, municipal roads, and water conservancy facilities, the permeability of concrete is a key indicator for evaluating project quality and durability. With the promotion of the "sponge city" concept, permeable concrete, as a core material for rainwater infiltration and mitigating urban flooding, has become increasingly important for accurate testing of its permeability coefficient. Concrete permeability coefficient testing is primarily achieved through permeability tests, which simulate the rainwater infiltration process, measuring the amount of water permeating a concrete specimen within a specific timeframe, and then calculating the permeability parameters. The test results directly guide the mix design, construction quality control, and project acceptance of permeable concrete. Current mainstream methods for testing concrete permeability are primarily based on industry standards such as the "Technical Specification for Permeable Concrete Pavement" (CJJ / T135-2009), employing permeability meters or custom-made molds to construct the testing apparatus. Existing testing molds typically consist of three parts: a water storage component, a specimen fixing structure, and a water collection device. Their working principle is as follows: after fixing a standard-sized concrete specimen (usually a cylinder or cube), water is continuously supplied to the top of the specimen, allowing water to permeate through under gravity. The permeability coefficient is calculated by collecting the amount of water seeping out and combining this with parameters such as time and water pressure. However, in actual testing, existing testing molds have numerous technical defects, severely affecting testing accuracy and ease of operation. Existing molds often use simple ring clamps or bolts to fix the specimens. However, due to manufacturing errors in the dimensions of concrete specimens, such as diameter deviations or uneven end faces, it is difficult for the clamps or bolts to fit evenly against the specimen surface. During testing, the specimens are prone to slight displacement due to water flow impact or lateral pressure. This displacement creates gaps at the contact surface between the specimen and the mold, causing a "flow around" phenomenon, where water leaks through the gaps instead of through the specimen body. This results in an overestimation of the measured permeability, ultimately distorting the permeability coefficient test results and failing to reflect the true permeability performance of the concrete. The permeability test has strict requirements on the water level (i.e., water pressure) above the specimen. The standard stipulates that a constant water level must be maintained to ensure stable permeability pressure. Existing mold water storage components are mostly open cylindrical structures, relying on manual water addition to maintain the water level. This is cumbersome and difficult to avoid water level fluctuations, such as liquid surface impact during water addition and water level drops due to evaporation. Although some molds have added overflow structures, the overflow port position is fixed, making it impossible to adjust the water storage height according to different specimen thicknesses, thus limiting their applicability. Furthermore, the overflow pipe and water receiving device are often rigidly connected, which can easily lead to overflow leakage due to installation errors, contaminating the test environment and affecting the accuracy of water measurement. In current testing processes, water level monitoring, solenoid valve control (if equipped), and water collection and measurement all require full manual supervision. For example, when the water level in the tank reaches a certain height, the water supply valve must be manually closed to prevent overflow; water measurement requires manual reading of the graduated cylinder scale and recording of the time. This not only increases the workload of operators but also easily affects the repeatability and reliability of test data due to human error such as reading delays and recording deviations. Especially in batch specimen testing scenarios, manual intervention can significantly reduce testing efficiency and make it difficult to meet the needs of rapid engineering testing.

[0003] Sealing the contact surface between the specimen and the mold is crucial for ensuring testing accuracy. Existing molds often use rubber gaskets or sealant, but these gaskets are fixed in size and cannot accommodate specimens of different diameters. Furthermore, long-term use of these gaskets can lead to aging and deformation, causing seal failure. In addition, some molds lack a sealing structure at the connection between the funnel and the water storage cylinder, making leakage during water supply easy and further exacerbating errors in water permeability measurement, potentially even leading to test failure.

[0004] Existing test molds are typically designed for specimens of specific sizes, such as Φ100mm×50mm cylindrical specimens. When testing specimens of different sizes (such as Φ150mm×100mm), the entire mold assembly needs to be replaced. This not only increases equipment procurement costs but also requires additional storage space, reducing the flexibility and economy of the testing work. Furthermore, the clamping structure of the molds is mostly fixed, making it impossible to fine-tune according to the actual size of the specimen, further limiting their applicability. Summary of the Invention

[0005] The technical problem to be solved by this utility model is to provide a concrete permeability test mold, which solves the technical problem that gaps easily appear between the specimen and the straight section sidewall of the funnel in the concrete permeability test, leading to water leakage and displacement of the water-receiving area, which in turn affects the accuracy of the permeability coefficient detection. It achieves the effect of adaptively filling gaps with variable diameter annular rubber rings, enhancing the sealing effect and specimen positioning stability, ensuring consistent effective water-receiving area, and improving the accuracy and reliability of permeability test data.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a concrete permeability test mold, including a base plate, a plurality of clamping columns arranged in a ring on the top surface of the base plate, a water storage cylinder in the middle of the top surface of the base plate, the plurality of clamping columns clamping the water storage cylinder inward, top support screws arranged in a ring at the same height on the side wall of the water storage cylinder, an L-shaped support at the end of the top support screw located in the water storage cylinder, a plurality of L-shaped support supports the same specimen, a funnel placed at the top opening of the water storage cylinder, and the upper half of the specimen extending into the funnel through the bottom opening of the funnel; The base plate is provided with a bracket, a water tank is provided on the bracket, and a drain pipe is provided on the side wall of the water tank, extending to the top of the funnel; An overflow pipe is provided on the side wall of the water storage cylinder, and the overflow pipe extends into the water receiving tank.

[0007] In a preferred embodiment, the base plate is provided with multiple sliding grooves, a slider is provided in the sliding groove, a spring is provided between the end of the sliding groove near the outer periphery of the base plate and the slider, and a clamping post is provided on the top of the slider.

[0008] In a preferred embodiment, one end of the top support screw located inside the water storage tank is connected to the L-shaped support member via a bearing; A butterfly-shaped head is provided on one end of the top support screw located outside the water storage tank.

[0009] In a preferred embodiment, an annular rubber ring is provided on the inner wall of the lower straight section of the funnel, and the inner diameter of the annular rubber ring is smaller than the diameter of the specimen. The annular rubber ring has a variable diameter structure, with the inner diameter of the annular rubber ring gradually increasing from bottom to top; The inner diameter and outer diameter of the bottom surface of the annular rubber ring are the same.

[0010] In a preferred embodiment, the drain pipe of the water tank is equipped with a solenoid valve, and a flexible hose is installed at the output end of the drain pipe, extending into the funnel.

[0011] In a preferred embodiment, the height of the overflow pipe is lower than the height of the top support screw.

[0012] In a preferred embodiment, the top surface of the water tank is provided with an inlet pipe, and an overflow pipe is provided with a flexible hose, the outlet end of which extends into the inlet pipe.

[0013] In a preferred embodiment, the water receiving tank is equipped with a liquid level sensor, and the liquid level sensor and the solenoid valve are connected to the same control module.

[0014] The concrete permeability test mold provided by this utility model, by adopting the above-described structure, has the following beneficial effects: (1) Through the combined design of “precise matching of the inner diameter of the funnel straight section with the diameter of the specimen + elastic sealing of the annular rubber ring”, the annular rubber ring, because its inner diameter is smaller than that of the specimen, can tightly fit the outer wall of the specimen and the inner wall of the funnel straight section after being compressed, completely filling the potential gap between the two and forming an annular sealing surface without dead angles. Compared with the “permeability measurement deviation” caused by the failure of the existing mold due to sealing, this solution can ensure that all water supply is applied to the top surface of the specimen without additional water flow loss, providing a real and accurate water volume data basis for the calculation of permeability coefficient, and significantly reducing the detection error caused by sealing problems; (2) The "self-positioning" function of the ring rubber ring can limit the lateral displacement of the funnel. Combined with the dual constraints of the "guide slope at the top of the straight section of the funnel" and the "positioning ring of the specimen inside the water storage cylinder", it can ensure that the axis of the specimen and the axis of the funnel always coincide, and the water-receiving area of ​​the top surface of the specimen is completely matched with its theoretical cross-sectional area, avoiding the displacement of the water-receiving area caused by the gap. Even if there is a slight deviation in the diameter of the specimen, the collaborative design of "drainage micro-hole + overflow pipe" can include the occasional seepage flow in the gap into the overflow water volume statistics, without interfering with the measurement of "water volume through the specimen". (3) The elastic seal of the ring rubber ring does not require precise alignment. The funnel can be placed to automatically form a seal. The "drainage micro-hole" design allows for the existence of small gaps. There is no need to make additional grinding corrections to the size of the specimen. The leak test is simple to operate. Only a small amount of water needs to be injected to observe and judge the sealing status. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0016] Figure 2 This is a top view of the base plate structure of this utility model.

[0017] Figure 3 This is a schematic diagram of the funnel structure of this utility model.

[0018] Figure 4 This is a schematic diagram of the top support screw structure of this utility model.

[0019] In the diagram: 1. Base plate; 2. Clamping column; 3. Water storage cylinder; 4. Top support screw; 401. Butterfly head; 402. Bearing; 5. L-shaped support; 6. Specimen; 7. Funnel; 8. Annular rubber ring; 9. Bracket; 10. Water tank; 11. Drain pipe; 12. Solenoid valve; 13. Hose; 14. Overflow pipe; 15. Water receiving tank; 16. Inlet pipe; 17. Liquid level sensor; 18. Control module; 19. Slide groove; 20. Slider; 21. Guide rod; 22. Spring. Detailed Implementation

[0020] like Figure 1-4 A concrete permeability test mold includes a base plate 1. Multiple clamping columns 2 are arranged in a ring on the top surface of the base plate 1. A water storage cylinder 3 is provided in the middle of the top surface of the base plate 1. The multiple clamping columns 2 clamp the water storage cylinder 3 inward. Top support screws 4 are arranged in a ring at the same height on the side wall of the water storage cylinder 3. The end of the top support screw 4 located inside the water storage cylinder 3 is provided with an L-shaped support 5. Multiple L-shaped support 5 support the same specimen 6. A funnel 7 is placed at the top opening of the water storage cylinder 3. The upper half of the specimen 6 extends into the funnel 7 through the bottom opening of the funnel 7. The base plate 1 is provided with a support 9, the support 9 is provided with a water tank 10, the side wall of the water tank 10 is provided with a drain pipe 11, and the drain pipe 11 extends to the top of the funnel 7. An overflow pipe 14 is provided on the side wall of the water storage cylinder 3, and the overflow pipe 14 extends into the water receiving tank 15.

[0021] In a preferred embodiment, the base plate 1 is provided with a plurality of sliding grooves 19, and a slider 20 is provided in the sliding groove 19. A spring 22 is provided between the end of the sliding groove 19 near the outer periphery of the base plate 1 and the slider 20, and a clamping post 2 is provided on the top of the slider 20.

[0022] In a preferred embodiment, one end of the top support screw 4 located inside the water storage tank 3 is connected to the L-shaped support member 5 via a bearing 402; A butterfly-shaped head 401 is provided on one end of the top support screw 4 located outside the water storage cylinder 3.

[0023] In a preferred embodiment, an annular rubber ring 8 is provided on the inner wall of the lower straight section of the funnel 7, and the inner diameter of the annular rubber ring 8 is smaller than the diameter of the specimen 6. The annular rubber ring 8 has a variable diameter structure, and the inner diameter of the annular rubber ring 8 gradually increases from bottom to top; The inner diameter and outer diameter of the bottom surface of the annular rubber ring 8 are the same.

[0024] In a preferred embodiment, the drain pipe 11 of the water tank 10 is equipped with a solenoid valve 12, and a flexible hose 13 is installed on the output end of the drain pipe 11, extending into the funnel 7.

[0025] In a preferred embodiment, the height of the overflow pipe 14 is lower than the height of the top support screw 4.

[0026] In a preferred embodiment, the top surface of the water receiving tank 15 is provided with a water inlet pipe 16, and the overflow pipe 14 is provided with a flexible hose, the output end of which extends into the water inlet pipe 16.

[0027] In a preferred embodiment, the water tank 15 is equipped with a liquid level sensor 17, and the liquid level sensor 17 and the solenoid valve 12 are connected to the same control module 18.

[0028] The concrete permeability test mold disclosed in this utility model is used when conducting concrete permeability tests: Fill the water tank 10 with enough clean water, turn on the power of the control module 18, and set the trigger threshold of the liquid level sensor 17 to "automatically close the solenoid valve 12 when the water level in the receiving tank 15 reaches 180mm" (to prevent the receiving tank from overflowing, and at the same time reserve enough space to collect the total amount of overflow and leakage). Manually loosen the top support screw 4 on the side wall of the water storage cylinder 3 to ensure that the L-shaped support 5 and the outer wall of the specimen 6 maintain a gap of 1-2mm (to facilitate the smooth flow of water around the specimen in the water storage cylinder and avoid the support from obstructing the stability of the water level); place the funnel 7 at the top opening of the water storage cylinder 3 to ensure that the annular rubber ring 8 is sealed and fitted to the outer wall of the specimen 6. Manually open the solenoid valve 12 and adjust the outlet position of the hose 13 so that the water flows slowly into the inner wall of the conical section of the funnel 7 (the flow rate is controlled at 50-80 mL / min to avoid water flow impact causing fluctuations in the water level in the storage tank). The water flows into the storage tank 3 through the bottom opening of the funnel 7 and begins to fill the storage tank. Continuously supply water until the water level in the storage tank 3 rises to the height of the overflow pipe 14 outlet. At this time, excess water flows into the receiving tank 15 through the overflow pipe 14. Observe for 3-5 minutes to confirm that the water level in the storage tank is always stable at the overflow pipe outlet plane (without obvious rise or fall). This indicates that the storage tank 3 has reached a "constant water level state". Record the constant water level height H1 in the storage tank at this time (that is, the vertical distance from the overflow pipe outlet to the bottom surface of the specimen 6. In this embodiment, the specimen height is 50mm and the overflow pipe is 40mm from the bottom of the storage tank, so H1=40mm). Close the solenoid valve 12.

[0029] Since the initial moisture content of concrete specimen 6 will affect the permeability, the specimen needs to be saturated pretreated under constant water level: keep the funnel 7 and the water storage cylinder 3 sealed, open the solenoid valve 12 again to maintain a constant water level in the water storage cylinder 3, and let the specimen 6 soak in the water for 20-30 minutes (adjust according to the density of concrete to ensure that the pores inside the specimen fully absorb water and avoid the specimen absorbing water during the test and interfering with the measurement of permeability).

[0030] After pretreatment, observe the overflow volume in the water receiving tank 15. If the water flow from the overflow pipe 14 is uniform and without interruption, it indicates that the water level in the storage tank remains constant. If the water flow is interrupted, check whether the water supply from the hose 13 is smooth and whether the annular rubber ring 8 is sealed (to rule out the possibility of water leakage causing a drop in water level). After the water level stabilizes again, empty the overflow water in the water receiving tank 15, wipe the residual moisture on the inner wall of the tank, and reset the water receiving tank (ensure that the hose connection between the inlet pipe 16 and the overflow pipe 14 is tight and there is no external leakage).

[0031] Press the “Test Start” button on the control module 18, and the solenoid valve 12 will open automatically. Water will flow continuously into the water storage tank 3 along the original path, and the electronic stopwatch will start timing (accuracy 0.1s). During the test, excess water in the water storage tank 3 will be continuously discharged into the water receiving tank 15 through the overflow pipe 14, and the water level in the tank will always be kept constant (i.e., H1=40mm remains unchanged), ensuring that the water pressure on the specimen 6 is stable.

[0032] Closely observe the water permeability at the bottom of specimen 6: When continuous water droplets (or water film) are first observed at the bottom of the specimen, record the "initial water permeability time t0" (used to determine whether the specimen has reached a stable water permeability state; if the specimen has high density, the initial water permeability time may be prolonged, requiring patient observation); after the water permeability state stabilizes (i.e., the water permeability rate at the bottom of the specimen is uniform and there are no obvious fluctuations), start recording the "formal timing start point t1", and simultaneously record the initial liquid level h1 in the water receiving tank 15 (read in real time through the liquid level sensor 17, accurate to 1 mm).

[0033] Set a fixed test duration (in this embodiment, it is set to 5 minutes, i.e., t=300s, which can be adjusted according to the water permeability of the specimen: the duration can be shortened for specimens with a large water permeability coefficient and extended for specimens with a small water permeability coefficient). During the test, keep the water supply stable and avoid touching the mold or water tank (to prevent displacement from causing water level fluctuations or leakage). If the liquid level in the water tank 15 is close to the set threshold (180mm), the test can be paused in advance, the water tank emptied, and the timing restarted (the time and water volume of each segment need to be recorded and finally calculated).

[0034] After the set test duration is reached, press the "Test Stop" button on the control module. The solenoid valve 12 will automatically close, the electronic stopwatch will stop timing, and the "official timing endpoint t2" will be recorded. The actual test duration t = t2 - t1 (accurate to 0.1s) will be calculated. At the same time, the final liquid level h2 in the water tank 15 will be read through the liquid level sensor 17, and the liquid level change Δh = h2 - h1 will be calculated.

[0035] According to the pre-calibrated parameters of the water receiving tank 15 (e.g., the cross-sectional area of ​​the water receiving tank S=100cmA) 2 Then the volume V = S × Δh), calculate the "total water volume Q" (in mL, accurate to 1 mL) collected in the water tank during the experiment; since this total water volume includes "overflow water Q discharged from the overflow pipe". 溢流 "and "water permeability Q through the specimen" 透 The reverse verification was performed using the water supply of water tank 10: the water level change in water tank 10 before and after the test was measured, and the "total water supply Q" was calculated based on the cross-sectional area of ​​the water tank. 总 In theory, Q 总 =Q (ideal condition excluding external leakage). If the deviation exceeds 5%, check for leakage and repeat the test.

[0036] After the test, keep the water level in the water tank 3 unchanged, and measure the height L of the specimen 6 again (to confirm that the specimen has no compression deformation during the test, accurate to 0.1mm). At the same time, record the ambient temperature of the test (20±2℃, temperature affects the viscosity of water, if the temperature deviation is large, viscosity correction needs to be made in the calculation).

[0037] Because the water level in the storage tank 3 remains constant, the "total water supply Q" during the experiment... 总All of it is used to "replenish overflow loss Q" 溢流 "and "water permeability Q through the specimen" 透 ", that is, the total water supply Q" 总 =Replenish overflow loss Q 溢流 +Water permeability through the specimen Q 透 However, in actual operation, if the annular rubber ring 8 is completely sealed (no leakage) and the water level in the storage tank is constant, then the "overflow loss Q" will be... 溢流 "Equals "water supply under non-permeable conditions" (which can be calculated from the overflow rate during the pretreatment stage), but for the sake of simplifying the calculation, this scheme directly uses "the total water volume Q collected in the water tank" and "the no-load water supply before the test (i.e., the overflow water volume when only water is supplied and no test specimen is placed)" to obtain the final "effective permeability Q". 有效 (To ensure data accuracy and eliminate interference from pure overflow).

Claims

1. A concrete permeability test mold, comprising a base plate (1), characterized in that: The top surface of the base plate (1) is provided with multiple clamping columns (2) arranged in a ring. The middle of the top surface of the base plate (1) is provided with a water storage cylinder (3). The multiple clamping columns (2) clamp the water storage cylinder (3) inward. The side wall of the water storage cylinder (3) is provided with a top support screw (4) arranged in a ring at the same height. The end of the top support screw (4) located in the water storage cylinder (3) is provided with an L-shaped support (5). The multiple L-shaped support (5) support the same specimen (6). A funnel (7) is placed at the top opening of the water storage cylinder (3). The upper half of the specimen (6) extends into the funnel (7) through the bottom opening of the funnel (7). The base plate (1) is provided with a bracket (9), the bracket (9) is provided with a water tank (10), the side wall of the water tank (10) is provided with a drain pipe (11), and the drain pipe (11) extends to the top of the funnel (7); The water storage tank (3) is provided with an overflow pipe (14) on its side wall, which extends into the water receiving tank (15).

2. The concrete permeability test mold according to claim 1, characterized in that: The base plate (1) is provided with multiple sliding grooves (19), and a slider (20) is provided in the sliding groove (19). A spring (22) is provided between the end of the sliding groove (19) near the outer periphery of the base plate (1) and the slider (20). A clamping column (2) is provided on the top of the slider (20).

3. The concrete permeability test mold according to claim 1, characterized in that: The top support screw (4) is connected to the L-shaped support (5) through a bearing (402) at one end inside the water storage tank (3); A butterfly-shaped head (401) is provided on one end of the top support screw (4) located outside the water storage cylinder (3).

4. The concrete permeability test mold according to claim 1, characterized in that: The funnel (7) has an annular rubber ring (8) on the inner wall of the straight section at the bottom. The inner diameter of the annular rubber ring (8) is smaller than the diameter of the specimen (6). The annular rubber ring (8) has a variable diameter structure, and the inner diameter of the annular rubber ring (8) gradually increases from bottom to top; The inner diameter and outer diameter of the bottom surface of the annular rubber ring (8) are the same.

5. The concrete permeability test mold according to claim 1, characterized in that: The water tank (10) has a solenoid valve (12) on its drain pipe (11) and a hose (13) on its output end, which extends into the funnel (7).

6. The concrete permeability test mold according to claim 1, characterized in that: The overflow pipe (14) is located at a height lower than the top support screw (4).

7. The concrete permeability test mold according to claim 1, characterized in that: The water receiving tank (15) is provided with an inlet pipe (16) on its top surface, and an overflow pipe (14) is provided with a flexible hose, the output end of which extends into the inlet pipe (16).

8. A concrete permeability test mold according to claim 5, characterized in that: The water tank (15) is equipped with a liquid level sensor (17), and the liquid level sensor (17) and the solenoid valve (12) are connected to the same control module (18).

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