Test device and method for measuring the water pressure of the coating-concrete interface penetration

Abstract

The present application relates to the technical field of building material detection, and discloses a test device and method for measuring coating-concrete interface penetration water pressure, which comprises a backwater pressurization module, an interface pressure measurement module, a pressure measurement module, an inlet pressure measurement module and a data acquisition module. The thin cavity is constructed by cooperation of a thin cavity forming piece and a concrete surface, the loop formed by the thin cavity, a capillary and a diaphragm type pressure sensor is filled with water and emptied of air, the water pressure in the thin cavity is transmitted to the diaphragm type pressure sensor through the water flow in the capillary to output the interface pressure, the data acquisition module extracts the interface pressure to execute a difference calculation program to obtain the interface pressure rise rate, the interface pressure rise rate is compared with a judgment threshold parameter to record the water arrival interface time node, the data acquisition module calculates the interface pressure change rate to extract the pressure platform feature and record the coating bubble expansion state, and the interface pressure drop rate is calculated to compare a sudden drop judgment threshold and record the coating peeling failure state.

Description

Technical Field

[0001] This invention relates to the field of building material testing technology, specifically to a test apparatus and method for measuring the water permeation pressure at the coating-concrete interface. Background Technology

[0002] Concrete surfaces are coated with a waterproof layer for protection. Water, pushed by pressure from the back side, can penetrate the concrete specimen and reach the interface between the coating and the concrete. This water accumulation at the interface generates interfacial water pressure, which can cause the coating to detach from the concrete surface, resulting in blistering or peeling failure. Current testing techniques for measuring the seepage water pressure at the coating-concrete interface are prone to having the pressure tapping channel open to the external environment. Outside air and liquids can enter the pressure tapping channel, altering the water pressure reading. Furthermore, the water seeping from the concrete carries hydration products and solid particles, which can accumulate and cause blockages in the testing instrument's internal channels.

[0003] When interpreting water flow penetration, existing technologies lack a procedure for extracting the interface pressure at adjacent measurement time points and performing differential calculations. It is difficult to obtain the interface pressure rise rate at high frequency and continuously, and it is also difficult to reliably record the time node when water reaches the interface by comparing the interface pressure rise rate with the judgment threshold parameter.

[0004] In the coating failure assessment stage, existing technologies are unable to continuously calculate the rate of change of interfacial pressure, lack an effective means to extract the pressure plateau characteristics by utilizing the dynamic equilibrium state of the interfacial pressure response curve to record the coating bubbling expansion state, and existing testing technologies are also unable to record the coating peeling failure state by calculating the rate of decrease of interfacial pressure and comparing it with the sudden drop judgment threshold.

[0005] Existing technologies make it difficult to measure the interfacial water pressure generated at the interface between the coating and concrete under backwater seepage in a closed state, and it is also difficult to accurately determine the failure state of the coating.

[0006] Therefore, this invention proposes a test apparatus and method for measuring the permeation pressure of water at the coating-concrete interface to address the shortcomings of existing technologies. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a test apparatus and method for measuring the infiltration water pressure at the coating-concrete interface, which improves upon the difficulties in measuring the interfacial water pressure generated at the interface between the coating and concrete under the influence of backwater infiltration and in reliably determining the failure state of the coating in existing technologies.

[0008] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a test apparatus for measuring the permeable water pressure at a coating-concrete interface, comprising: The backwater pressurization module has a sealing gasket on the edge and is attached to the back of the concrete specimen to form a closed backwater pressurization chamber. A water supply pressurization system is connected to the back water pressurization chamber for injecting water and pressurizing it to generate seepage flow. An inlet pressure measurement module, installed on the backwater pressurization module, is used to measure the internal pressure of the backwater pressurization chamber and output the inlet pressure; The interface pressure tapping module includes a thin cavity forming element, a capillary tube, and an epoxy sealing layer. The thin cavity forming element is attached to the front surface of the concrete specimen to be coated to form a thin cavity for accumulating moisture. The first end of the capillary tube is connected to the thin cavity, and the end of the capillary tube leads out of the concrete specimen. The epoxy sealing layer fills the interface gap between the outer wall of the capillary tube and the surrounding structure. The pressure measurement module is a diaphragm pressure sensor with an internal isolation diaphragm. The liquid inlet end of the diaphragm pressure sensor is connected to the end of the capillary tube, and is used to sense the water pressure transmitted by the thin cavity and output the interface pressure. An air venting and water injection valve is connected in series between the capillary tube and the diaphragm pressure sensor. After the air venting and water injection valve is filled with water, it is in a closed and locked state, so that an incompressible and sealed pressure tapping circuit for venting air is formed between the thin cavity, the capillary tube and the diaphragm pressure sensor. The data acquisition module is communicatively connected to the inlet pressure measurement module and the diaphragm pressure sensor, respectively. The data acquisition module includes a non-volatile memory, which stores a judgment threshold parameter. The data acquisition module synchronously acquires and records the inlet pressure and the interface pressure.

[0009] Preferably, the thin cavity forming component is a pressed sheet, a thin sintered metal porous sheet, or a porous ceramic sheet; The epoxy sealing layer fills the junction between the outer wall of the capillary and the concrete specimen, as well as the junction between the outer wall of the capillary and the thin cavity forming element, sealing the connection gaps between the structures.

[0010] Preferably, the water supply pressurization system is equipped with a high-pressure water supply pump and a pressure stabilizing valve, and the water supply pressurization system applies a seepage pressure that gradually increases to the back water pressurization chamber.

[0011] Preferably, the data acquisition module has a data sampling frequency parameter, and the data acquisition module synchronously extracts the inlet pressure and the interface pressure according to the data sampling frequency parameter.

[0012] Preferably, the data acquisition module calculates the pressure drop of the concrete specimen using a formula and outputs the curve of the pressure drop value of the concrete specimen changing over time simultaneously; The formula is as follows: ; in, This represents the pressure drop of the concrete specimen; Represents inlet pressure; This represents the pressure on the interface.

[0013] A second aspect of the present invention provides a test method for measuring the permeable water pressure at a coating-concrete interface, applied to a test apparatus for measuring the permeable water pressure at a coating-concrete interface, comprising the following steps: Water is injected into the interface pressure tapping module through the venting and water injection valve to expel air, and then the venting and water injection valve is closed and locked to establish a closed pressure tapping circuit. Start the water supply pressurization system to inject water and pressurize the back water pressurization chamber; The inlet pressure output by the inlet pressure measurement module and the interface pressure output by the pressure measurement module are obtained in real time through the data acquisition module. The data acquisition module identifies and records the time points or states of moisture reaching the interface, coating blistering expansion, and coating peeling failure based on the characteristics of the interface pressure change over time and a preset judgment threshold parameter.

[0014] Preferably, the step of identifying and recording the arrival of moisture at the interface includes: The rate of increase of the interface pressure is calculated in real time. When the rate of increase is greater than the determination threshold parameter, the corresponding time node is registered as the time node when water arrives at the interface.

[0015] Preferably, the step of identifying and recording the blistering expansion state of the coating includes: Monitor the interface pressure response curve. When it is detected that the interface pressure no longer rises continuously, but is within the plateau fluctuation threshold and the duration reaches the duration threshold, extract the pressure plateau feature as a record marker of the coating bubbling expansion state.

[0016] Preferably, the step of identifying and recording the coating peeling failure state includes: The rate of change of the interface pressure is calculated continuously in real time. When a sudden drop in interface pressure is detected and the calculated rate of drop in interface pressure is greater than the set threshold for sudden drop judgment, the current moment is recorded as the node where the coating peeling failure state occurs.

[0017] Preferably, it further includes a decoupling analysis step: The data acquisition module calculates the pressure drop of the concrete specimen, which is used to quantitatively evaluate the permeation resistance characteristics of the concrete substrate itself, and realizes a comprehensive decoupled analysis of the waterproof performance of the coating and the substrate.

[0018] This invention provides a test apparatus and method for measuring the permeable water pressure at the coating-concrete interface. It offers the following advantages: 1. This invention constructs a thin cavity by combining a thin cavity forming component with a concrete surface. The capillary tube and the thin cavity are connected. The epoxy resin material is cured to form an epoxy sealing layer that blocks the flow channels of external air and external liquids into the thin cavity and the capillary tube. The exhaust and water injection valve is in a closed and locked state under pressure measurement. The internal channel of the capillary tube is only connected to the thin cavity and the diaphragm pressure sensor. The external air pressure cannot enter the capillary tube and change the water pressure value. The diaphragm pressure sensor has an isolation diaphragm to prevent the water flow inside the capillary tube from directly contacting the internal sensing element. The isolation diaphragm prevents the concrete hydration products and solid particles carried in the water flow from accumulating in the internal channel of the diaphragm pressure sensor and causing blockage.

[0019] 2. This invention reads various interface pressure data points on the interface pressure response curve through a data acquisition module, extracts the interface pressure at adjacent measurement time points, and executes a difference calculation program. The data acquisition module calculates the interface pressure at the next time point and the interface pressure at the previous time point to obtain a first difference value. The data acquisition module calculates the interface pressure at the next measurement time point and the interface pressure at the previous measurement time point to obtain a second difference value. The data acquisition module divides the first difference value and the second difference value to obtain the interface pressure rise rate. The data acquisition module compares the interface pressure rise rate value with a judgment threshold parameter. The data acquisition module registers the measurement time point corresponding to the interface pressure rise rate value exceeding the judgment threshold parameter as the water arrival time node.

[0020] 3. This invention continuously calculates the interface pressure change rate through a data acquisition module. When the interface pressure change rate is within the plateau fluctuation threshold and the duration reaches the duration threshold, the interface pressure response curve is identified as being in a dynamic equilibrium state and extracted as a pressure plateau feature. The data acquisition module records the pressure plateau feature as a coating bubbling expansion state. The data acquisition module extracts the interface pressure at different measurement time points and calculates the interface pressure drop rate. By comparing the interface pressure drop rate with the sudden drop judgment threshold, if the interface pressure drop rate is greater than the sudden drop judgment threshold, it means that the interface pressure response curve has a pressure sudden drop feature. The data acquisition module records the pressure sudden drop feature as a coating peeling failure state. Attached Figure Description

[0021] Figure 1 This is a structural block diagram of the present invention; Figure 2 This is a partial schematic diagram of the interface pressure tapping module and connection structure of the present invention; Figure 3 This is a flowchart of the method of the present invention; Figure 4 This is a comparison chart of interface pressure response curves in a specific application example. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See attached document Figure 1 This invention provides a test apparatus and method for measuring the permeation water pressure at the coating-concrete interface. The test apparatus for measuring the permeation water pressure at the coating-concrete interface includes a backwater pressurization module, an interface pressure tapping module, a pressure measurement module, an inlet pressure measurement module, and a data acquisition module. The backwater pressurization module is sealed to the back of the concrete specimen, and the backwater pressurization module and the back of the concrete specimen form a backwater pressurization chamber. The backwater pressurization chamber is connected to a water supply pressurization system.

[0024] The interface pressure tapping module is set on the front of the concrete specimen at the interface to be coated. The interface pressure tapping module includes a thin cavity forming element and a capillary. The thin cavity forming element is attached to the concrete surface, and the thin cavity forming element and the concrete surface form a thin cavity. The capillary is connected to the thin cavity. The capillary is led out from the side or back of the concrete specimen and is sealed with epoxy. The internal cavity of the capillary is not connected to the outside.

[0025] The pressure measurement module is a diaphragm pressure sensor, which is connected to the capillary tube. The diaphragm pressure sensor measures the interface pressure, the inlet pressure measurement module measures the inlet pressure, and the data acquisition module simultaneously acquires and records the inlet pressure and interface pressure.

[0026] See attached document Figure 1 and attached Figure 2 The water supply pressurization system injects water into the back water pressurization chamber and pressurizes it to generate water flow. The inlet pressure measurement module measures the pressure inside the back water pressurization chamber to obtain the inlet pressure. The water flow passes through the concrete specimen and reaches the interface between the concrete specimen and the coating. The water flow enters the thin cavity formed by the thin cavity forming part and the concrete surface. The water flow inside the thin cavity enters the capillary tube. The loop formed by the thin cavity, the capillary tube and the diaphragm pressure sensor is filled with water and the air is emptied. The water pressure inside the thin cavity is transmitted to the diaphragm pressure sensor through the water flow inside the capillary tube. The diaphragm pressure sensor senses the pressure and outputs the interface pressure.

[0027] ; In the formula, Represents interface pressure; Represents inlet pressure; This represents the pressure drop of the concrete specimen.

[0028] See attached document Figure 1 and attached Figure 3 A sealing gasket is provided at the edge of the back water pressurization chamber. The edge of the back water pressurization chamber is attached to the back of the concrete specimen. The sealing gasket is located between the edge of the back water pressurization chamber and the back of the concrete specimen. The sealing gasket deforms under pressure, so that the back water pressurization chamber and the back of the concrete specimen form a closed area. The water flow is confined to the inside of the closed area and seeps into the interior of the concrete specimen.

[0029] The water supply pressurization system is equipped with a high-pressure water supply pump and a pressure regulating valve. The outlet of the high-pressure water supply pump is connected to the water supply pipeline, and the other end of the water supply pipeline is connected to the back water pressurization chamber. The high-pressure water supply pump injects water into the back water pressurization chamber. The pressure regulating valve is installed on the water supply pipeline and adjusts the water pressure value entering the back water pressurization chamber, generating osmotic water pressure inside the back water pressurization chamber.

[0030] The inlet pressure measurement module is installed on the back water pressurization chamber housing. The probe of the inlet pressure measurement module extends into the back water pressurization chamber. The inlet pressure measurement module senses the water flow pressure value inside the back water pressurization chamber, generates the inlet pressure, and transmits the inlet pressure to the data acquisition module.

[0031] ; In the formula, Represents inlet pressure; This represents the output pressure of the high-pressure water supply pump; This represents the pressure drop in the water supply pipeline.

[0032] See attached document Figure 2 The interface pressure tapping module is set on the front of the concrete specimen at the interface to be coated. The interface pressure tapping module has a thin cavity forming element and a capillary. The thin cavity forming element is attached to the surface of the concrete specimen. The thickness of the thin cavity forming element is in the range of 0.1 mm to 0.3 mm, and the diameter of the thin cavity forming element is in the range of 10 mm to 20 mm. The structure of the thin cavity forming element is a pressure tapping sheet, a thin sintered metal porous sheet, or a porous ceramic sheet. The thin cavity forming element establishes a volume space to accommodate water flow in a local area on the surface of the concrete specimen through the micro-groove structure reserved on the side close to the concrete specimen, or by utilizing the interconnected internal pores of the porous material itself. The volume space is defined as the thin cavity, which collects the water flow that seeps out from the inside of the concrete specimen.

[0033] The capillary tube extends into the thin cavity and connects to its internal volume. The capillary tube extends along the surface of the concrete specimen, with its end passing over the edge and exiting from either the side or back of the specimen. Epoxy resin is used to fill the junction between the capillary tube and the concrete specimen, as well as between the capillary tube and the thin cavity. The epoxy resin cures to form an epoxy sealing layer, which seals the gaps between the various structures. Preferably, a T-joint is connected in series between the capillary tube and the diaphragm pressure sensor. The third end of the T-joint is connected to an air vent and water injection valve. This valve is open to the outside environment when filled with water and vented, and closed and locked during pressure measurement. In this state, the internal channel of the capillary tube only connects to the thin cavity and the diaphragm pressure sensor; the water flow inside the capillary tube is disconnected from the external environment, preventing external air pressure from entering the capillary tube and altering the water pressure value.

[0034] ; In the formula, Represents the volume of a thin cavity; Represents the diameter of the thin cavity forming element; This represents the thickness of the thin cavity forming part.

[0035] See attached document Figure 2 and attached Figure 3 The pressure measurement module is a diaphragm pressure sensor, with the capillary end connected to the liquid inlet of the diaphragm pressure sensor. The diaphragm pressure sensor contains an isolation diaphragm that prevents water flow inside the capillary from directly contacting the internal sensing element. Preferably, this diaphragm pressure sensor is a micro-volume displacement sensor, where the volume change of the medium required for full-scale deformation is much smaller than the volume of the thin cavity, ensuring the sensitivity of pressure transmission. Concrete hydration products and solid particles carried in the water flow are blocked outside the isolation diaphragm, preventing solid particles from accumulating and causing blockages in the internal channels of the diaphragm pressure sensor. The isolation diaphragm is also resistant to water immersion.

[0036] The water flow inside the thin cavity pushes the water flow inside the capillary tube. The water flow inside the capillary tube compresses the surface of the diaphragm, and the water pressure forces the diaphragm to deform. The diaphragm pressure sensor converts the deformation of the diaphragm into an output electrical signal, which corresponds to the interface pressure value. The signal terminal of the diaphragm pressure sensor is connected to the signal terminal of the data acquisition module. The diaphragm pressure sensor continuously sends the interface pressure to the data acquisition module, which receives and records the interface pressure.

[0037] In a preferred data processing method, the interface pressure is calculated using the following formula. However, those skilled in the art should understand that using other equivalent linear or nonlinear fitting algorithms to replace the following formula to obtain the interface pressure still falls within the scope of protection of this invention: ; In the formula, Represents interface pressure; This represents the sensitivity coefficient of a diaphragm pressure sensor. Represents the output electrical signal; This represents the zero-point offset of a diaphragm pressure sensor.

[0038] Based on the above-mentioned test apparatus for measuring the permeable water pressure at the coating-concrete interface, the present invention also provides a method for measuring the permeable water pressure at the coating-concrete interface, the method comprising the following steps: See attached document Figure 3 The method includes specimen preparation, pouring concrete into a mold, and demolding the concrete after it has cured to obtain a concrete specimen. The concrete specimen has a length of 300 mm, a width of 300 mm, and a thickness of 50 mm. The surface of the concrete specimen to be coated is cleaned, and a cavity-forming element is placed at the interface to be coated on the front of the concrete specimen. The cavity-forming element and the concrete surface work together to construct a cavity.

[0039] The capillary tube is inserted into the thin cavity at its tip, and the tube body is laid along the front of the concrete specimen, extending beyond the boundary of the specimen to the side or back. Epoxy resin is filled at the interface between the capillary tube's outer wall and the concrete specimen surface, and at the interface between the capillary tube's outer wall and the thin cavity. The epoxy resin cures to form an epoxy sealing layer, which blocks external air and liquid from entering the thin cavity and the flow channels within the capillary tube.

[0040] The coating process is performed on the front surface of the concrete specimen, consisting of a primer coat, an intermediate coat, and a top coat. The primer coat is applied to the front surface of the concrete specimen, as well as the outer sides of the cavity-forming parts and capillaries. The intermediate coat is applied over the primer coat, and the top coat is applied over the intermediate coat. The coating covers the cavity-forming parts and the capillaries on the front surface of the concrete specimen. The concrete specimen and the coating are simultaneously cured statically until they reach the specified age standard.

[0041] See attached document Figure 3The test apparatus for measuring the permeable water pressure at the coating-concrete interface follows the steps of pipeline filling and venting, and zero-point calibration. The venting and water injection valve, located between the capillary tube and the diaphragm pressure sensor, is opened, and an auxiliary pump with both vacuum suction and water injection functions is connected. Degassed water is slowly injected into the venting and water injection valve. Utilizing the dissolving properties of the degassed water on micro-bubbles and the squeezing effect of the liquid, air inside the circuit is expelled into the pores or micro-gap at the front end of the concrete specimen; alternatively, micro-venting channels are pre-reserved in the design of thin-cavity components, and these channels are sealed with epoxy resin after water injection and venting. After continuously venting internal air bubbles, the venting and water injection valve is closed and locked. The water flow inside the circuit occupies the channel volume, establishing an incompressible pressure transmission medium.

[0042] Water flow into the loop ceases, leaving the water inside the loop static and pressureless. The inlet pressure measurement module generates an initial inlet pressure value under pressureless conditions. The data acquisition module receives and records this initial inlet pressure value, setting it as the inlet measurement zero point. Similarly, the diaphragm pressure sensor generates an initial interface pressure value under pressureless conditions. The data acquisition module receives and records this initial interface pressure value, setting it as the interface measurement zero point.

[0043] It should be noted that, to avoid premature damage to the cured coating caused by applying calibration pressure after assembly and connection, the data acquisition module of this system pre-stores the calibration relationship curves of the pressure sensors. Specifically, the graded calibration, hysteresis test, and calibration slope acquisition processes for the inlet pressure measurement module and the diaphragm pressure sensor are preferably completed on an independent calibration bench before specimen preparation. In the pre-calibration stage, standard pressure values ​​with progressively increasing and decreasing values ​​(e.g., 0 MPa and 0.1 MPa and 0.2 MPa and 0.3 MPa) are independently applied to the inlet pressure measurement module and the diaphragm pressure sensor, respectively. The data acquisition module simultaneously records and calculates the inlet hysteresis parameter and the interface hysteresis parameter. The data acquisition module compares the hysteresis parameter with the system's preset allowable error threshold. If it is within the allowable error range, the pressure sensor's return accuracy is confirmed to be qualified. Subsequently, the data acquisition module establishes and stores the calibration relationship based on the standard pressure values ​​obtained in the pre-calibration stage and the measured pressure values. ; In the formula, This represents the measured pressure value; Represents the standard pressure value; Represents the calibration slope; This represents the calibration intercept.

[0044] Based on the aforementioned pre-stored and solidified calibration relationship, and combined with the measurement zero point established after the pipeline is filled with water and vented, the system can directly enter the high-precision actual seepage measurement state, thereby avoiding interference to the interface of the coating specimen during the calibration process.

[0045] See attached document Figure 3 The test apparatus for measuring the seepage water pressure at the coating-concrete interface performs a back-water pressurization seepage procedure. The water supply pressurization system injects water into the back-water pressurization chamber and increases the water pressure. The water supply pressurization system establishes the seepage pressure using either a step-by-step pressurization method or a constant pressure loading method. In the step-by-step pressurization method, the water supply pressurization system applies the first-level pressure to the back-water pressurization chamber and maintains the first-level pressure for a preset holding time. Then, the water supply pressurization system increases the water pressure to the second-level pressure and maintains the second-level pressure. In the constant pressure loading method, the water supply pressurization system applies the target pressure to the back-water pressurization chamber and maintains the target pressure throughout the entire test cycle. The water flow is pushed from the back of the concrete specimen by the water pressure inside the back-water pressurization chamber, thus generating seepage water flow.

[0046] The seepage water flows through the inside of the concrete specimen and penetrates to the front of the specimen. The inlet pressure measurement module measures the fluid pressure inside the backwater pressurization chamber and outputs the inlet pressure. The diaphragm pressure sensor measures the transmitted pressure inside the thin cavity and outputs the interface pressure. The data acquisition module performs a synchronous sampling step. The data acquisition module has a data sampling frequency parameter, which is greater than or equal to 1Hz. The data acquisition module synchronously extracts the inlet pressure and interface pressure according to the data sampling frequency parameter. The data acquisition module records the extraction time as the corresponding measurement time point. The data acquisition module synchronously saves the measurement time point, inlet pressure, and interface pressure.

[0047] The test apparatus for measuring the permeable water pressure at the coating-concrete interface is equipped with a temperature sensor. The temperature sensor probe is deployed inside the test environment. The temperature sensor generates ambient temperature values. The data acquisition module synchronously receives the ambient temperature values ​​according to the data sampling frequency parameters and records the ambient temperature values ​​at the corresponding measurement time points. The data acquisition module reads the interface pressure at different measurement time points. The data acquisition module uses the measurement time points as the horizontal axis values ​​and the interface pressure as the vertical axis values. The data acquisition module plots the points on a two-dimensional chart based on the coordinate values. The data acquisition module connects the points to generate an interface pressure response curve.

[0048] See attached document Figure 3The test device for measuring the permeation water pressure at the coating-concrete interface executes the result interpretation steps. The permeation water flows from inside the concrete specimen to the interface between the coating and the concrete specimen. When the water flow does not enter the thin cavity, the diaphragm pressure sensor cannot sense the water pressure fluctuation. The interface pressure output by the diaphragm pressure sensor remains at the zero-point measurement baseline position. The interface pressure continuously recorded by the data acquisition module produces a horizontal line on the time axis.

[0049] The seepage water flows out from inside the concrete specimen and into the thin cavity. The water flow into the thin cavity causes an increase in water pressure. The water pressure is transmitted to the diaphragm pressure sensor through a capillary tube. The diaphragm pressure sensor senses the water pressure change and outputs the increased interface pressure. The data acquisition module reads each interface pressure data point on the interface pressure response curve. The data acquisition module extracts the interface pressure at adjacent measurement time points and executes the difference calculation program.

[0050] The data acquisition module calculates the interface pressure at the next time point and the interface pressure at the previous time point to obtain the first difference. The data acquisition module calculates the interface pressure at the next measurement time point and the previous measurement time point to obtain the second difference. The data acquisition module divides the first difference and the second difference to obtain the interface pressure rise rate. The data acquisition module internally stores a judgment threshold parameter. This judgment threshold parameter can be obtained by conducting independent water seepage tests on standard specimens in advance and combining the results of specimen cross-sectional humidity detection or visual observation. It is pre-stored in the non-volatile memory of the data acquisition module. The data acquisition module compares the interface pressure rise rate with the judgment threshold parameter. If the interface pressure rise rate exceeds the judgment threshold parameter, it means that the interface pressure deviates from the measurement baseline and rises abruptly. The data acquisition module registers the measurement time point corresponding to the interface pressure rise rate exceeding the judgment threshold parameter as the water arrival time node.

[0051] In a preferred determination mechanism, the rate of increase of interface pressure is calculated using the following difference algorithm formula. However, using other equivalent curve slope extraction or first derivative calculation methods to replace this formula does not depart from the essence of the invention: ; In the formula, This represents the rate of increase in interface pressure. This represents the interface pressure at a later point in time. This represents the interface pressure at the previous point in time. This represents the next measurement time point; This represents the previous measurement time point.

[0052] In practical engineering applications, in order to eliminate electrical signal noise interference caused by high-frequency sampling, the data acquisition module can perform sliding window filtering on the continuously acquired interface pressure data points before executing the above difference calculation program; or, the previous measurement time point and the next measurement time point are not two adjacent sampling points, but two sampling points on the time axis with a preset period (e.g., 5s to 10s) to ensure the accuracy of the rise rate calculation.

[0053] See attached document Figure 3 After completing the registration procedure for the time node of water arrival at the interface, the test device for measuring the infiltration water pressure at the coating-concrete interface enters the coating failure judgment stage. The water flow that has infiltrated into the thin cavity accumulates and exerts an outward pushing force on the back of the coating. The diaphragm pressure sensor continuously outputs an ever-increasing interface pressure, and the interface pressure value received by the data acquisition module increases accordingly. The interface pressure response curve plotted by the data acquisition module extends upward.

[0054] When the pushing force of the water flow inside the thin cavity exceeds the critical value of the adhesion between the coating and the concrete surface, the coating partially detaches from the concrete surface, creating a blistering area between the coating and the concrete surface. This blistering area generates an expanded volume to accommodate the water flow. The infiltrating water fills this expanded volume, causing the local water pressure to reach a dynamic equilibrium state. The diaphragm pressure sensor measures a stable water pressure value and outputs the interface pressure within a constant range. The data acquisition module continuously calculates the interface pressure change rate, storing a platform fluctuation threshold and a duration threshold. When the data acquisition module determines that the continuously measured interface pressure change rate is within the platform fluctuation threshold and the duration reaches the duration threshold, the data acquisition module identifies the interface pressure response curve as being in a dynamic equilibrium state and extracts it as a pressure platform feature. The data acquisition module records this pressure platform feature as the coating blistering expansion state.

[0055] It should be noted that if the data acquisition module determines that the interface pressure change rate exceeds the platform fluctuation threshold, or the duration does not reach the duration threshold, it means that the interface pressure has not yet entered a dynamic equilibrium state, and the data acquisition module continues to execute the data acquisition and pressure change rate calculation program.

[0056] Enlarged blistering areas can cause damage to the coating, such as cracks penetrating the external environment or large-scale peeling of the coating from the concrete surface. This creates a fluid pressure relief channel connecting the external environment and the interior of the thin cavity. Water flows outward along this channel, causing a decrease in water pressure. The diaphragm pressure sensor measures this decrease and outputs a reduced interface pressure. The data acquisition module detects this decrease in interface pressure, extracts the interface pressure at different measurement time points, and calculates the rate of interface pressure drop. The sudden drop threshold, calibrated based on previous destructive tests and pre-stored in the data acquisition module, is used to compare the interface pressure drop rate with the sudden drop threshold. If the interface pressure drop rate exceeds the threshold, the interface pressure response curve exhibits a pressure drop characteristic. The data acquisition module records this pressure drop characteristic as a coating peeling failure state.

[0057] Furthermore, if the data acquisition module determines that the interface pressure drop rate is less than or equal to the sudden drop determination threshold, it indicates that the coating has not yet failed to peel off. The data acquisition module continues to synchronously extract and monitor the interface pressure in a loop until the test cycle ends or the failure determination is triggered.

[0058] Preferably, the formula for calculating the rate of decrease in interface pressure is as follows. Those skilled in the art can use an equivalent difference algorithm or a slope calculation method after smoothing filtering to replace this formula, which also falls within the scope of protection of this invention: ; In the formula, Represents the rate of decrease in interface pressure; This represents the interface pressure before the sudden drop; This represents the interface pressure after a sudden drop; This represents the measurement point after the sudden drop; This represents the measurement point before the sudden drop.

[0059] In addition, the data acquisition module simultaneously extracts the inlet pressure and interface pressure at the measurement time point and has a built-in substrate pressure drop calculation program. The data acquisition module uses formulas... The pressure drop of the concrete specimen is calculated, and the curve of the pressure drop value of the concrete specimen changing over time is output synchronously to quantitatively evaluate the permeation resistance characteristics of the concrete substrate itself, thereby realizing a comprehensive decoupled analysis of the waterproof performance of the coating and the substrate.

[0060] Specific application examples: To further aid in understanding the specific implementation logic and working principle of the present invention, the following provides a specific application example and experimental verification effect, using the impermeability test scenario of an epoxy resin waterproof coating and concrete specimen in an underground engineering project.

[0061] In this application scenario, it is necessary to evaluate the time point at which water penetrates the concrete substrate and reaches the coating interface under continuous backwater pressure, as well as the critical state at which the coating eventually blisters and peels off. To illustrate the data calculation and state assessment process within the system, the following calculations will use the actual test parameters from the scenario and incorporate them into the calculation program within the data acquisition module.

[0062] First, the test apparatus for measuring the infiltration water pressure at the coating-concrete interface undergoes pipeline filling and venting procedures, along with zero-point calibration. The diaphragm pressure sensor generates an initial output electrical signal under pressureless conditions, and the sensitivity coefficient of the diaphragm pressure sensor, pre-stored in the data acquisition module, is known. The output electrical signal is equal to 0.5 MPa / V under zero-point no-voltage condition. The voltage is equal to 0.02V. The data acquisition module substitutes this value into the formula to calculate the interface pressure at this point and sets it as the zero-point offset of the diaphragm pressure sensor. : ; The subsequent backwater pressurization and seepage step is executed, with the water supply pressurization system employing a constant pressure loading method. The high-pressure water supply pump applies the target pressure to the backwater pressurization chamber, at which point the high-pressure water supply pump outputs pressure. The pressure drop in the water supply pipeline is equal to 1.05 MPa. The inlet pressure is 0.05 MPa. The data acquisition module calculates the inlet pressure as follows: ; The seepage water penetrated the front of the concrete specimen. In the initial stage of the test (before reaching the interface), the diaphragm pressure sensor output a stable electrical signal of 0.02V, which was used to calculate the interface pressure. Maintain at 0 MPa.

[0063] When the test reaches the previous measurement time point When the time interval is 3600s, the interface pressure extracted by the data acquisition module at the previous time point is... The pressure was 0.01 MPa; as the water flowed into the thin cavity, at the next measurement time point... When the time is equal to 3610s, the diaphragm pressure sensor outputs an electrical signal. The voltage drops to 0.18V. The data acquisition module then calculates the interface pressure at a given time point using the aforementioned formula: ; The data acquisition module executes a differential calculation program to obtain the rate of increase of interface pressure: ; The data acquisition module stores a threshold parameter, which is equal to 0.002 MPa / s. Since the calculated rate of increase of the interface pressure at this time is 0.007 MPa / s, which is greater than the threshold parameter of 0.002 MPa / s, it means that the interface pressure deviates from the measurement baseline and rises abruptly. The data acquisition module records the corresponding measurement time point as the time node when water arrives at the interface.

[0064] As water continues to accumulate, the pressure inside the thin cavity rises and reaches dynamic equilibrium, causing the coating to bubble and expand. The data acquisition module simultaneously extracts the stable interface pressure at the measurement time point. The pressure drop of the concrete specimen is 0.85 MPa. The data acquisition module calculates the pressure drop of the concrete specimen to evaluate the permeation resistance of the substrate. ; When the test continues to the measurement point before the sudden drop At 7200s, the pressure at the front interface suddenly drops. The pressure was maintained at 0.85 MPa; a large-area peeling of the coating suddenly occurred, creating a fluid pressure relief channel. Measurements were taken at the time points following the sudden drop. At 7210s, the interface pressure suddenly drops. The pressure dropped sharply to 0.35 MPa. The data acquisition module calculated the rate of pressure decrease on the interface. ; The data acquisition module has a pre-stored threshold for detecting sudden pressure drops of 0.015 MPa / s. Since the calculated interface pressure drop rate of 0.05 MPa / s is greater than the threshold of 0.015 MPa / s, the data acquisition module identifies the pressure drop feature and records this as a coating peeling failure state.

[0065] To demonstrate the monitoring sensitivity and implementation effect of the device of the present invention, a comparative verification scenario was constructed using an experimental platform. The direct pressure measurement method of the present invention was compared with the traditional indirect evaluation method based on permeability estimation, and the corresponding operating condition charts were output.

[0066] The conclusions are as follows: See attached document Figure 4 , attached Figure 4 The solid line represents the measured interface pressure of the device of the present invention, and the dashed line represents the interface pressure evaluated by the traditional indirect method.

[0067] From the appendix Figure 4It is evident that traditional indirect evaluation methods, unable to penetrate the actual interface between the coating and concrete, exhibit slow curve changes, only responding at the end of the test after the coating completely ruptures and leaks water, thus completely masking the actual process of interfacial water pressure accumulation. In contrast, the system of this invention accurately captures the abrupt rise in water pressure reaching the interface around 3600s, the subsequent dynamic equilibrium plateau period of coating bubbling expansion (around 0.85MPa), and the sharp drop in pressure around 7200s due to coating peeling failure. The testing device of this invention achieves real-time, in-situ, and precise decoupled analysis of interfacial permeable water pressure.

Claims

1. A test apparatus for measuring the permeable water pressure at the coating-concrete interface, characterized in that, include: The backwater pressurization module has a sealing gasket on the edge and is attached to the back of the concrete specimen to form a closed backwater pressurization chamber. A water supply pressurization system is connected to the back water pressurization chamber for injecting water and pressurizing it to generate seepage flow. An inlet pressure measurement module, installed on the backwater pressurization module, is used to measure the internal pressure of the backwater pressurization chamber and output the inlet pressure; The interface pressure tapping module includes a thin cavity forming element, a capillary tube, and an epoxy sealing layer. The thin cavity forming element is attached to the front surface of the concrete specimen to be coated to form a thin cavity for accumulating moisture. The first end of the capillary tube is connected to the thin cavity, and the end of the capillary tube leads out of the concrete specimen. The epoxy sealing layer fills the interface gap between the outer wall of the capillary tube and the surrounding structure. The pressure measurement module is a diaphragm pressure sensor with an internal isolation diaphragm. The liquid inlet end of the diaphragm pressure sensor is connected to the end of the capillary tube, and is used to sense the water pressure transmitted by the thin cavity and output the interface pressure. An air venting and water injection valve is connected in series between the capillary tube and the diaphragm pressure sensor. After the air venting and water injection valve is filled with water, it is in a closed and locked state, so that an incompressible and sealed pressure tapping circuit for venting air is formed between the thin cavity, the capillary tube and the diaphragm pressure sensor. The data acquisition module is communicatively connected to the inlet pressure measurement module and the diaphragm pressure sensor, respectively. The data acquisition module includes a non-volatile memory, which stores a judgment threshold parameter. The data acquisition module synchronously acquires and records the inlet pressure and the interface pressure.

2. The test apparatus for measuring the permeable water pressure at the coating-concrete interface according to claim 1, characterized in that, The thin cavity forming component has the structural form of a pressed sheet, a thin sintered metal porous sheet, or a porous ceramic sheet; The epoxy sealing layer fills the junction between the outer wall of the capillary and the concrete specimen, as well as the junction between the outer wall of the capillary and the thin cavity forming element, sealing the connection gaps between the structures.

3. The test apparatus for measuring the permeable water pressure at the coating-concrete interface according to claim 2, characterized in that, The water supply pressurization system is equipped with a high-pressure water supply pump and a pressure stabilizing valve. The water supply pressurization system applies a seepage pressure that gradually increases to the back water pressurization chamber.

4. The test apparatus for measuring the permeable water pressure at the coating-concrete interface according to claim 1, characterized in that, The data acquisition module has a data sampling frequency parameter, and the data acquisition module synchronously extracts the inlet pressure and the interface pressure according to the data sampling frequency parameter.

5. The test apparatus for measuring the permeable water pressure at the coating-concrete interface according to claim 1, characterized in that, The data acquisition module calculates the pressure drop of the concrete specimen using a formula and outputs the curve of the change of the pressure drop value of the concrete specimen over time in a synchronous manner. The formula is as follows: ； in, This represents the pressure drop of the concrete specimen; Represents inlet pressure; This represents the pressure on the interface.

6. A test method for measuring the permeable water pressure at the coating-concrete interface, characterized in that, The test apparatus for measuring the permeable water pressure at the coating-concrete interface as described in any one of claims 1-5 comprises the following steps: Water is injected into the interface pressure tapping module through the venting and water injection valve to expel air, and then the venting and water injection valve is closed and locked to establish a closed pressure tapping circuit. Start the water supply pressurization system to inject water and pressurize the back water pressurization chamber; The inlet pressure output by the inlet pressure measurement module and the interface pressure output by the pressure measurement module are obtained in real time through the data acquisition module. The data acquisition module identifies and records the time points or states of moisture reaching the interface, coating blistering expansion, and coating peeling failure based on the characteristics of the interface pressure change over time and a preset judgment threshold parameter.

7. The test method for measuring the permeable water pressure at the coating-concrete interface according to claim 6, characterized in that, The steps of identifying and recording moisture reaching the interface include: The rate of increase of the interface pressure is calculated in real time. When the rate of increase is greater than the determination threshold parameter, the corresponding time node is registered as the time node when water arrives at the interface.

8. The test method for measuring the permeable water pressure at the coating-concrete interface according to claim 6, characterized in that, The step of identifying and recording the bubbling expansion state of the coating includes: Monitor the interface pressure response curve. When the interface pressure stops rising and is within the plateau fluctuation threshold and the duration reaches the duration threshold, extract the pressure plateau feature as a record marker of the coating bubbling expansion state.

9. The test method for measuring the permeable water pressure at the coating-concrete interface according to claim 6, characterized in that, The steps for identifying and recording coating peeling failure status include: The rate of change of the interface pressure is calculated continuously in real time. When a sudden drop in interface pressure is detected and the calculated rate of drop in interface pressure is greater than the set threshold for sudden drop judgment, the current moment is recorded as the node where the coating peeling failure state occurs.

10. The test method for measuring the permeable water pressure at the coating-concrete interface according to claim 6, characterized in that, It also includes a decoupling analysis step: The data acquisition module calculates the pressure drop of the concrete specimen, which is used to quantitatively evaluate the permeation resistance characteristics of the concrete substrate itself, and realizes a comprehensive decoupled analysis of the waterproof performance of the coating and the substrate.

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