Concrete capillary water absorption test device and method

Abstract

The invention provides a concrete capillary water absorption test device and method, and belongs to the technical field of concrete durability tests.The concrete capillary water absorption test device comprises a fluid storage tank, test fluid is placed in the fluid storage tank, the fluid storage tank is placed on a weighing device, and the weighing device is used for measuring the total weight of the fluid storage tank and the test fluid in the fluid storage tank; a concrete sample is fixed above the fluid storage tank through a supporting device, and the bottom end of the concrete sample is immersed in the test fluid. According to the invention, errors in the capillary water absorption test can be reduced, continuous and high-fidelity monitoring of the water absorption process can be realized, especially tiny changes in the initial stage and the later stage of water absorption can be accurately captured, and the accuracy of the result of the capillary water absorption test is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete durability testing, and in particular relates to a concrete capillary water absorption testing device and method. Background Art

[0002] Civil engineering materials, such as concrete, mortar, and masonry, are the cornerstone of modern infrastructure. Their long-term durability is crucial for ensuring structural safety and extending service life. Among various complex environmental factors, water intrusion is one of the most common and leading causes of material degradation and structural damage. Water migration through the capillary pore network within the material not only directly affects the material's physical properties but can also trigger a series of complex physical and chemical degradation processes, including steel corrosion, freeze-thaw damage, salt crystallization, and the diffusion of harmful ions. Ultimately, this can significantly weaken the material's mechanical properties and the durability of the overall structure, even leading to premature structural failure, resulting in significant economic losses and safety hazards.

[0003] Therefore, accurately evaluating the ability of civil engineering materials to resist water intrusion is a core component of materials science research, engineering quality control, and structural life prediction. The capillary water absorption test, as an intuitive and effective testing method, characterizes a material's pore structure and impermeability by quantifying the amount of water absorbed by a material per unit time due to capillary action. It has become a widely adopted key performance evaluation indicator both domestically and internationally, providing essential data support for the development of new materials, the precise assessment of the safety status of existing structures, and the scientific development of repair plans.

[0004] The traditional capillary water absorption test method is to remove the sample from the water at a preset time point, wipe it, weigh it, and then return it to the water tank. First, it is extremely difficult to wipe the moisture on the surface of the sample to a completely consistent degree, which affects the accuracy of the weighing results. In addition, the test process is artificially interrupted periodically, which not only destroys the natural continuity of the capillary water absorption process and causes the migration front and saturation distribution of water within the material to be artificially disturbed, but more importantly, it makes it almost impossible to capture the key dynamic characteristics of the material's rapid water absorption in the initial stage of water absorption (usually within the first few minutes to an hour). Data from this stage is crucial for understanding the material's pore connectivity and surface wettability. Summary of the Invention

[0005] In response to the defects or shortcomings in the existing technology, the present invention provides a concrete capillary water absorption test device and method, which can reduce the errors in the capillary water absorption test and realize continuous and high-fidelity monitoring of the water absorption process. In particular, it can accurately capture the subtle changes in the early and late stages of water absorption, thereby ensuring the accuracy of the results of the capillary water absorption test.

[0006] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, an embodiment of the present invention provides a concrete capillary water absorption test device, comprising a fluid storage tank containing a test fluid, the fluid storage tank being placed on a weighing device for measuring the total weight of the fluid storage tank and the test fluid therein, a concrete specimen being fixed above the fluid storage tank by a supporting device, and the bottom end of the concrete specimen being immersed in the test fluid.

[0007] Furthermore, the support device includes an electric telescopic rod and a support platform. The electric telescopic rods are provided with three electric telescopic rods, which are evenly distributed at the edge of the support platform and are hinged to the support platform through a rotating shaft.

[0008] Furthermore, an inclination sensor is provided on the support platform, and the inclination sensor is located at the geometric center of the three electric telescopic rods.

[0009] Furthermore, the electric telescopic rod and the tilt sensor are both electrically connected to the controller.

[0010] Furthermore, a bracket is fixed on the lower surface of the support platform, and the concrete sample is fixed on the bottom surface of the support platform through the bracket.

[0011] Furthermore, the fluid storage tank is connected to a fluid supply device, and the fluid supply device includes a liquid storage box. The liquid storage box is connected to the fluid storage tank through a pipeline, and a water pump is provided on the pipeline.

[0012] Furthermore, a liquid level sensor is provided in the fluid storage tank, and the water pump and the liquid level sensor are both electrically connected to the controller.

[0013] In a second aspect, an embodiment of the present invention provides a concrete capillary water absorption test method, using a concrete capillary water absorption test device as described above, comprising the following steps: Step S101: Fix the sample to the support platform and set the parameters required for the test; Step S102: Adjust the support platform to a horizontal level; Step S103: After leveling is completed, the controller controls the fluid supply device to inject the test fluid into the fluid storage tank. At the same time, the liquid level sensor monitors the liquid level until the liquid level reaches a preset depth. After the liquid level stabilizes, the controller records the total mass of the fluid storage tank measured by the weighing device at this time as the initial reference mass M0; Step S104: Calculate and record the cumulative water absorption of the sample at the current moment at set intervals; Step S105: When it is detected that the level is lower than the set lower threshold, the test fluid is replenished to restore the level to the target height; Step S106: When the preset total test duration is reached, or other end conditions set by the user are met, the system automatically stops all operations, records and generates visual data.

[0014] Furthermore, in step S104, the cumulative water absorption of the sample at the current moment is calculated and recorded at intervals of set time. Specifically, the controller reads the real-time mass reading M of the weighing device at preset time intervals. t , combined with the pre-recorded initial reference mass M 0， Calculate and record the current cumulative water absorption of the sample Mabsorbed = M0-M t .

[0015] Furthermore, in step S105, when it is detected that the liquid level is lower than the set lower limit threshold, the test fluid is replenished to restore it to the target height. Specifically, if it is detected that the liquid level is lower than the set lower limit threshold, the controller will temporarily suspend the validity of the water absorption data and immediately start the fluid conveying device to perform a small amount of water replenishment until the liquid level returns to the target height. After the water replenishment is completed, wait for the liquid level to stabilize briefly. The central control and data processing module may update the weighing system reading at this time to the new reference mass M0', and then resume normal recording of the water absorption data.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention places a fluid storage tank on a weighing device and secures the concrete specimen above the fluid storage tank via a support device, so that the bottom of the concrete device is immersed in the test fluid. This method uses an indirect measurement method to measure the mass reduction of the fluid storage tank, combined with an automated process that eliminates physical contact with the specimen. This fundamentally eliminates human and systematic errors introduced by manual sampling, wiping, weighing, and placing the specimen back. This enables continuous, high-fidelity monitoring of the water absorption process, and is particularly capable of accurately capturing subtle changes in the early and late stages of water absorption.

[0017] 2. The present invention provides a support device, uses an electric telescopic rod to support the support platform, and sets an inclination sensor on the support platform to enable the support device to achieve automatic leveling, ensuring that all samples begin to absorb water under a completely consistent horizontal reference. The automatic fluid supply system accurately maintains a constant immersion depth, eliminating data distortion caused by uneven equipment or liquid level fluctuations, and greatly improving the comparability of results between different samples and different test batches. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the capillary water absorption test device in Example 1 of the present invention; Figure 2 This is a schematic structural diagram of a supporting device in Embodiment 1 of the present invention; Figure 3Schematic diagram of the structure of the fluid supply device in Example 1 of the present invention; Among them, 1. Fluid storage tank; 2. Weighing device; 3. Concrete sample; 4. Electric telescopic rod; 5. Support platform; 6. Inclination sensor; 7. Bracket; 8. Liquid storage tank; 9. Water pump. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Example 1 A typical embodiment of the present invention is as follows Figure 1 As shown, a concrete capillary water absorption test device includes a fluid storage tank 1, in which a test fluid is placed. The fluid storage tank 1 is placed on a weighing device 2, which is used to measure the total weight of the fluid storage tank 1 and the test fluid therein. A concrete sample 3 is fixed above the fluid storage tank 1 by a supporting device so that the bottom end of the concrete sample 3 can be immersed in the test fluid.

[0021] Specifically, the fluid storage tank 1 is hollow inside and open at the top. The fluid storage tank 1 is used to contain the test fluid. In this embodiment, the test fluid is water. A weighing device 2 is provided at the bottom of the fluid storage tank 1. The weighing device 2 adopts weighing equipment such as common electronic balances, force sensor arrays or electromagnetic force balance sensors on the market, which can realize continuous or intermittent accurate measurement of the total mass of the fluid storage tank 1 and the fluid therein at a very high frequency. The weighing device 2 is electrically connected to the controller. During the test, the controller collects the real-time total mass of the fluid storage tank 1 from the weighing device 2 at a set frequency, and calculates the cumulative water absorption and instantaneous water absorption of the sample based on the initial mass M0 (recorded when the liquid level is stable and the sample just contacts the liquid surface) and the real-time mass.

[0022] Wherein, the cumulative water absorption of the sample = M0- M t .

[0023] Where: M0 is the total mass of the initial fluid storage tank; M t is the total mass of the real-time fluid storage tank.

[0024] The instantaneous water absorption of the sample refers to the mass of water absorbed by the sample per unit time. It is calculated by the difference in the cumulative water absorption between two adjacent time points. The specific calculation formula is as follows: Instantaneous water absorption = (M 累积吸水(t) -M 累积吸水(t-Δt) ) / Δt; Among them, M 累积吸水(t) = M0- M t , represents the cumulative water absorption at time t; M 累积吸水(t-Δt) = M0- M (t-Δt) , represents the cumulative water absorption at the previous moment; Δt is the time interval; After expansion, we can get: Instantaneous water absorption = (M (t-Δt) -M t ) / Δt.

[0025] By setting the sampling frequency (such as every second or every minute) of the controller, the system can continuously monitor the mass change of the weighing device 2, thereby calculating the instantaneous water absorption rate of the material in different time periods in real time.

[0026] like Figure 2 As shown, the support device includes an electric telescopic rod 4 and a support platform 5. The electric telescopic rod 4 is a common electric telescopic rod on the market, and the length of the electric telescopic rod 4 can be accurately controlled by a stepper motor. In this embodiment, three electric telescopic rods 4 are provided, and the three electric telescopic rods 4 are evenly distributed at the edge of the support platform 5, providing three-point support for the support platform 5, thereby fixing the support platform 5 above the storage tank fluid 1.

[0027] Specifically, the telescopic end of the electric telescopic rod 4 is fixed to the ground, and the other end of the electric telescopic rod 4 is hinged to the edge of the support platform 5, so that the electric telescopic rod 4 and the support platform 5 can rotate relative to each other. A tilt sensor 6 is provided on the support platform 5. The tilt sensor 6 is located at the geometric center of the three electric telescopic rods 4. The electric telescopic rod 4 and the tilt sensor 6 are electrically connected to the controller, so that the electric telescopic rod 4 and the tilt sensor 6 are used to realize automatic leveling of the support platform 5.

[0028] During leveling, when the inclination sensor 6 detects that the support platform 5 is tilted, it feeds a signal back to the controller. The controller then calculates the adjustment amount for the three electric telescopic rods 4 based on the inclination angle. The controller then controls the three electric telescopic rods 4 to adjust synchronously. After adjustment, the inclination angle is re-tested to determine whether it meets the standard, until the support platform 5 reaches the preset horizontal accuracy requirement. By leveling the support platform 5, the immersion depth of multiple concrete specimens 3 on the support platform 5 can be effectively guaranteed to be consistent, thereby ensuring the accuracy of the test results.

[0029] Specifically, first, a plane coordinate system is established with the position of the tilt sensor 6 as the origin O. The position coordinates of the three electric telescopic rods 4 are: Point A: (r·cos(0°), r·sin(0°)) = (r, 0); Point B: (r·cos(120°), r·sin(120°)) = (-r / 2, r√3 / 2); Point C: (r·cos(240°), r·sin(240°)) = (-r / 2, -r√3 / 2); Where r is the distance from the electric telescopic rod to the geometric center.

[0030] The tilt angle of the support platform relative to the horizontal plane is measured by the tilt sensor 6, including: αx: the tilt angle around the X axis; αy: the tilt angle around the Y axis.

[0031] Based on the inclination angle data, calculate the height deviation of the three support points relative to the ideal horizontal plane: ΔhA = r·sin(αx); ΔhB = r·sin(αx)·cos(120°) + r·sin(αy)·sin(120°) = -r·sin(αx) / 2+ r√3·sin(αy) / 2; ΔhC = r·sin(αx)·cos(240°) + r·sin(αy)·sin(240°) = -r·sin(αx) / 2- r√3·sin(αy) / 2.

[0032] Calculate the required adjustment for each telescopic rod (positive values ​​extend, negative values ​​shorten): ΔLA = -ΔhA = -r·sin(αx); ΔLB = -ΔhB = r·sin(αx) / 2 - r√3·sin(αy) / 2; ΔLC = -ΔhC = r·sin(αx) / 2 + r√3·sin(αy) / 2.

[0033] After receiving the signal from the inclination sensor 6, the controller calculates the adjustment amount for each telescopic rod according to the above formula and then controls the stepper motor to drive the telescopic rods to adjust synchronously. After the adjustment is completed, the inclination sensor 6 value is re-read to determine whether it meets the preset horizontal accuracy requirement (such as ±0.1°). If it does not meet the standard, the calculation and adjustment process is repeated until the support platform 5 reaches a horizontal state.

[0034] A bracket 7 is fixed on the lower surface of the support platform 5, which is used to fix the concrete sample 3 to ensure that the lower surface of the sample can be immersed in the test fluid. The bracket 7 is fixed to the bottom surface of the support platform 5 by bolts to ensure the stability of the bracket 7 and the support platform 5. A storage hole is provided on the lower surface of the bracket 7, and the concrete sample 3 can be placed in the storage hole. A through hole is provided on the side wall of the storage hole. A positioning hole is pre-opened on the concrete sample 3, and the positioning hole corresponds to the through hole. The concrete sample 3 is fixed on the bracket 7 by inserting a positioning pin into the positioning hole and the through hole.

[0035] The fluid storage tank 1 is connected to the fluid supply device, such as Figure 3As shown, the fluid replenishment device includes a liquid tank 8 containing test fluid. The liquid tank 8 is connected to the fluid storage tank 1 via a pipeline, and a water pump 9 is installed on the pipeline. The fluid storage tank 1 is also provided with a liquid level sensor. The liquid level sensor adopts a laser range finder, an ultrasonic liquid level sensor, or a capacitive liquid level sensor to reduce contact with the test liquid to avoid physical disturbance of the liquid surface. The liquid level sensor is used to detect the height of the liquid level in the fluid storage tank 1 in real time. The water pump 9 and the liquid level sensor are both electrically connected to a controller. When the liquid level sensor detects that the liquid level has dropped to a preset lower threshold due to water absorption or evaporation of the sample, the controller starts the water pump 9 to replenish fluid from the liquid tank 8 to the fluid storage tank 1 until the liquid level returns to the set target height. By providing a fluid replenishment device, the liquid level in the fluid storage tank 1 is maintained constant, the immersion depth of the test specimen is ensured, data distortion caused by liquid level fluctuations is eliminated, and the accuracy of the test structure is ensured.

[0036] The controller stores relevant data such as time, water absorption and water absorption rate in real time, and dynamically displays the water absorption kinetic curve on the human-computer interaction interface. After the test, it can automatically generate a test report and allow the user to export raw data and processing structure through standard data interfaces (such as USB and Ethernet).

[0037] By setting up a support device, using an electric telescopic rod to support the support platform, and setting an inclination sensor on the support platform, the support device can be automatically leveled, ensuring that all samples begin to absorb water under a completely consistent horizontal reference. The automatic fluid supply system accurately maintains a constant immersion depth, eliminating data distortion caused by uneven equipment or liquid level fluctuations, and greatly improving the comparability of results between different samples and different test batches.

[0038] Example 2 This embodiment provides a concrete capillary water absorption test method, using a concrete capillary water absorption test device as described in Example 1, including the following steps: Step S101: Initialization and parameter setting: Place the dry sample on the sample holder, fix the holder to the support platform, and set the parameters required for the test through the human-computer interaction interface; Step S102: Automatic leveling: After starting the test, the controller executes the automatic leveling program and drives the electric telescopic rod to adjust the support platform to a horizontal level; Step S103: Initial water injection and reference mass recording; after leveling is completed, the controller controls the fluid supply device to inject the test fluid into the fluid storage tank, and the liquid level sensor monitors the liquid level until the liquid level reaches the preset depth. After the liquid level stabilizes, the controller records the total mass of the fluid storage tank measured by the weighing device at this time as the initial reference mass M0.

[0039] Step S104: The controller reads the real-time mass reading Mt of the weighing device at a preset time interval (e.g., once per second or once per minute). Calculate and record the current cumulative water absorption of the sample Mabsorbed = M0-M t .

[0040] Step S105: The liquid level sensor continuously monitors the liquid level. If the liquid level falls below the set lower threshold, the controller temporarily suspends the validity of the water absorption data (or marks it) and immediately activates the fluid delivery device to replenish a small amount of water until the liquid level returns to the target height. After replenishment, the central control and data processing module may update the current weighing system reading to the new reference mass M0' (for subsequent incremental calculations or to deduct the impact of water replenishment through an algorithm) and then resume normal recording of water absorption data. This closed-loop control ensures dynamic and constant liquid level throughout the test.

[0041] Step S106: Test End and Data Processing. When the preset total test duration is reached or other user-defined termination conditions are met, the system automatically stops all operations. Based on all recorded valid data, the controller automatically generates a complete "time-to-cumulative water absorption" data table and a water absorption kinetics graph, which can be exported by the user.

[0042] By adopting an indirect measurement method of measuring the mass reduction of the fluid storage tank, combined with an automated process without physical contact with the sample throughout the process, the human errors and systematic errors introduced by manual sampling, wiping, weighing, and returning operations are fundamentally eliminated. This enables continuous, high-fidelity monitoring of the water absorption process, and is particularly capable of accurately capturing subtle changes in the early and late stages of water absorption.

[0043] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and scope of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A concrete capillary water absorption test device, characterized in that: The apparatus comprises a fluid storage tank containing a test fluid, the fluid storage tank being placed on a weighing device for measuring the total weight of the fluid storage tank and the test fluid therein, a concrete sample being fixed above the fluid storage tank by a supporting device, and the bottom end of the concrete sample being immersed in the test fluid.

2. A concrete capillary water absorption test device as claimed in claim 1, characterized in that: The supporting device includes an electric telescopic rod and a supporting platform. Three electric telescopic rods are provided. The three electric telescopic rods are evenly distributed at the edge of the supporting platform and are hinged to the edge of the supporting platform.

3. A concrete capillary water absorption test device as claimed in claim 2, characterized in that: The support platform is provided with an inclination sensor, which is located at the geometric center of the three electric telescopic rods.

4. A concrete capillary water absorption test device as claimed in claim 3, characterized in that: The electric telescopic rod and the tilt sensor are both electrically connected to the controller.

5. A concrete capillary water absorption test device as claimed in claim 2, characterized in that: A bracket is fixed on the lower surface of the support platform, and the concrete sample is fixed on the bottom surface of the support platform through the bracket.

6. A concrete capillary water absorption test device as claimed in claim 1, characterized in that: The fluid storage tank is connected to a fluid supply device, and the fluid supply device includes a liquid storage box. The liquid storage box is connected to the fluid storage tank through a pipeline, and a water pump is provided on the pipeline.

7. A concrete capillary water absorption test device as claimed in claim 1, characterized in that: A liquid level sensor is also provided in the fluid storage tank, and the water pump and the liquid level sensor are both electrically connected to the controller.

8. A concrete capillary water absorption test method, using a concrete capillary water absorption test device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step S101: Fix the sample to the support platform and set the parameters required for the test; Step S102: Adjust the support platform to a horizontal level; Step S103: After leveling is completed, the controller controls the fluid supply device to inject the test fluid into the fluid storage tank. At the same time, the liquid level sensor monitors the liquid level until the liquid level reaches a preset depth. After the liquid level stabilizes, the controller records the total mass of the fluid storage tank measured by the weighing device at this time as the initial reference mass M0; Step S104: Calculate and record the cumulative water absorption of the sample at the current moment at set intervals; Step S105: When it is detected that the level is lower than the set lower threshold, the test fluid is replenished to restore the level to the target height; Step S106: When the preset total test duration is reached, or other end conditions set by the user are met, the system automatically stops all operations, records and generates visual data.

9. A concrete capillary water absorption test method according to claim 8, characterized in that: In step S104, the cumulative water absorption of the sample at the current moment is calculated and recorded at intervals of set time. Specifically, the controller reads the real-time mass reading M of the weighing device at preset time intervals. t , combined with the pre-recorded initial reference mass M 0， Calculate and record the current cumulative water absorption of the sample Mabsorbed = M0-M t .

10. A concrete capillary water absorption test method according to claim 8, characterized in that: In step S105, when it is detected that the liquid level is lower than the set lower limit threshold, the test fluid is replenished to restore it to the target height. Specifically, if it is detected that the liquid level is lower than the set lower limit threshold, the controller will temporarily suspend the validity of the water absorption data and immediately start the fluid conveying device to perform a small amount of water replenishment until the liquid level returns to the target height. After the water replenishment is completed, wait for the liquid level to stabilize briefly. The central control and data processing module may update the weighing system reading at this time to the new reference mass M0', and then resume normal recording of the water absorption data.

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