Device and method for accelerated erosion aging test of concrete under simulated sustained load

Abstract

This invention discloses a test apparatus and method for simulating accelerated erosion and aging of concrete under continuous load, relating to the field of concrete material aging testing technology. The apparatus includes a continuous loading device and an accelerated erosion device. The continuous loading device consists of a reaction frame structure, a jack, and a steel plate pad. During the continuous load test on the concrete cube specimen, the specimen is placed at one end inside the reaction frame structure, and the jack is placed at the other end. The loading head of the jack is isolated from the concrete cube specimen by a steel plate pad to prevent excessive concentration of loading force. The accelerated erosion device consists of an erosion liquid tank, two liquid-separating rubber cylinders, positive and negative electrodes, and a power supply. This invention, using the aforementioned test apparatus and method for simulating accelerated erosion and aging of concrete under continuous load, simulates the coupled effect of continuous load and chemical erosion on marine concrete structures in actual operating environments, significantly shortening the test cycle and providing an effective means for studying the aging laws of concrete.

Description

Technical Field

[0001] This invention relates to the field of concrete material aging testing technology, and in particular to a test apparatus and method for simulating accelerated erosion aging of concrete under continuous load. Background Technology

[0002] As an important water conservancy infrastructure, concrete dams are subjected to a combination of factors during long-term operation, including continuous loads, sulfate and chloride ion erosion, carbonation, and temperature and humidity cycles, which leads to material performance degradation and affects the safety and durability of the dam.

[0003] Currently, research on concrete aging, both domestically and internationally, largely focuses on performance degradation under single-factor effects, such as simple chemical erosion tests or mechanical load tests. However, in actual engineering projects, concrete structures are often exposed to the combined effects of multiple factors, particularly the synergistic effect of continuous load and chemical erosion, which significantly accelerates the material aging process.

[0004] The existing test equipment has the following shortcomings: it lacks the ability to simulate the coupled effect of continuous load and chemical erosion; the test cycle is long, making it difficult to obtain the aging law in a short period of time; it cannot accurately control multiple parameters such as load, temperature, and humidity during the test process; and the data acquisition system is imperfect, making it difficult to achieve real-time monitoring of the entire process. Summary of the Invention

[0005] The purpose of this invention is to provide a test device and method for simulating the accelerated erosion and aging of concrete under continuous load, so as to simulate the actual dam operating environment and systematically study the aging law of concrete under the action of multiple factors.

[0006] To achieve the above objectives, the present invention provides a test device for simulating the accelerated erosion and aging of concrete under continuous load, including a continuous loading device and an accelerated erosion device; the continuous loading device consists of a reaction frame structure, a jack and a steel pad, the steel pad is placed between the loading head of the jack and the concrete cube specimen, the concrete cube specimen is placed at one end inside the reaction frame structure, and the other end of the concrete cube specimen is placed on the jack. The accelerated erosion device consists of an erosion liquid tank, two liquid-separating rubber cylinders, positive and negative electrodes, and a power supply. The two liquid-separating rubber cylinders and the concrete cube specimen divide the erosion liquid tank into two parts. The erosion liquid tank is equipped with a temperature control and circulation mechanism and a data acquisition mechanism.

[0007] Preferably, the circulation pump is located at the top of the etching solution tank, which contains an etching solution, which is sulfate or chloride ions.

[0008] Preferably, the positive and negative electrodes are placed in two independent etching liquid areas separated by a concrete cube specimen and two liquid-separating rubber cylinders in the etching liquid tank. The positive and negative electrodes are connected to a power source, which is connected to a current controller. Through the action of the positive and negative electrodes, the etching ions in the etching solution form a closed electrical circuit through the concrete cube specimen, resulting in faster and more severe etching.

[0009] Preferably, the current controller adjusts the current range from 0 to 5A and the voltage range from 0 to 50V.

[0010] Preferably, the corrosion liquid tank is connected to a temperature control and circulation mechanism, which includes a temperature control box, a heating and cooling device, and a humidity controller. The temperature control range is -20℃ to +80℃, and the humidity control range is 30%-95%RH.

[0011] The method for using the test apparatus for simulating accelerated erosion and aging of concrete under continuous load includes the following steps: 1. Specimen preparation: Install the standard concrete cube specimen in the specimen station, and place it in the corrosive liquid tank after installation, ensuring that the position is centered. Insert rubber rods on both sides of the specimen. The concrete cube specimen and the rubber rods on both sides form an isolation zone inside the corrosive liquid tank. S2. Applying load: Using jacks, a continuous axial load is applied to the concrete cube specimen through the reaction frame structure. After preloading and centering, the load is applied in stages to the design stress level. S3. Injecting solution: Inject the prepared same etching solution into the space on both sides of the test specimen and the space isolated by the rubber rods in the etching solution tank. The liquid level should be flush with the top surface of the test specimen to keep the liquid on both sides of the test specimen and the rubber rods from contacting each other and to isolate them. S4. Add positive and negative electrodes: Add positive and negative electrodes to both sides of the etching solution tank respectively; S5. Start the system: Turn on the power supply to the positive and negative electrodes, apply an appropriate voltage, and let the positive and negative electrodes pass through the erosion solution and the concrete cube specimen to form a closed electrical circuit; S6. Start the temperature control and circulation mechanism, set the temperature circulation program, and start the data acquisition mechanism; S7. Process monitoring: Regularly record parameters such as specimen strain, load value, and solution concentration through a data acquisition mechanism. S8. Performance testing: Take out the specimens at predetermined time intervals to conduct mechanical property testing and microstructure analysis. S9. Data analysis: Combining experimental data and theoretical models, establish a model for predicting the aging patterns and lifespan of concrete.

[0012] Therefore, the present invention employs the above-mentioned test device and method for simulating the accelerated erosion and aging of concrete under continuous load. The loading system simulates the continuous stress on the dam concrete, the erosion system simulates the chemical environment of the reservoir water, the electrochemical system accelerates the erosion process and shortens the test cycle, and the temperature control system simulates changes in the natural environment. The parameters are precise and controllable, and key parameters such as load, concentration, temperature, and voltage can be precisely controlled and adjusted. The data acquisition system monitors changes in material properties in real time, thereby obtaining the aging law of concrete under the coupled effects of multiple factors in a relatively short period of time.

[0013] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the test device for simulating the accelerated erosion and aging of concrete under continuous load according to the present invention. Figure 2 This is a side view of the test device for simulating the accelerated erosion and aging of concrete under continuous load according to the present invention. Figure Labels 1. Liquid-sealing rubber cylinder; 2. Reaction frame structure; 3. Concrete cube specimen; 4. Etching liquid tank; 5. Jack; 6. Temperature control box; 7. Circulation pump; 8. Etching solution; 9. Power supply. Detailed Implementation

[0015] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0017] Example Please see Figures 1-2 The present invention provides a test device for simulating the accelerated erosion and aging of concrete under continuous load, including a continuous loading device and an accelerated erosion device.

[0018] The continuous loading device consists of a reaction frame structure 2, a jack 5, and a steel plate pad. The jack 5 provides the load for the concrete cube specimen 3, and the reaction frame structure 2 provides a stable continuous load for the concrete cube specimen 3. During the continuous load test of the concrete cube specimen, the specimen is placed at one end inside the reaction frame structure 2, and the jack 5 is placed at the other end. The loading head of the jack 5 is isolated from the concrete cube specimen 3 by a steel plate pad to prevent the loading force from being too concentrated.

[0019] The accelerated erosion device consists of an erosion liquid tank 4, two liquid-separating rubber cylinders 1, positive and negative electrodes, and a power supply 9. When conducting the rapid erosion test on the concrete cube specimen, the pre-arranged concrete cube specimen 3 and its continuous loading test device are placed in a tank containing corrosive salt ion solution. The left and right ends of the specimen are inserted into the liquid-isolating rubber cylinders 1, ensuring that the rubber cylinders 1 tightly fill the gap between the concrete cube specimen 3 and the inner wall of the erosion tank 4, and preventing liquid from passing through between the rubber cylinders 1 and the inner wall of the erosion tank 4. This creates a liquid-isolating barrier inside the erosion tank 4, consisting of two rubber cylinders 1 sandwiching a concrete cube specimen 3, thus isolating the corrosive liquid in the tank 4 into two parts. Then, positive and negative electrodes are placed into the two corrosive liquid areas separated by the concrete cube specimen 3 and the two rubber cylinders 1, respectively, within the erosion tank 4. After the power supply 9 is turned on, the positive and negative electrodes accelerate the penetration of corrosive salt ions from the two corrosive liquid areas within the erosion tank 4 through the concrete cube specimen 3, thereby achieving accelerated erosion of the concrete cube specimen 3. Meanwhile, the acceleration of erosion can be controlled by adding a temperature control device to the erosion tank; the degree of accelerated erosion of the concrete cube specimen can also be monitored by using a salt ion monitor on the concrete cube specimen.

[0020] The jack 5 applied a continuous load to the concrete cube specimen 3, the load size of which was adjustable, to simulate the stress state of different parts of the dam.

[0021] The circulating pump 7 is located at the top of the etching solution tank 4, which is made of stainless steel. The etching solution tank 4 contains an etching solution 8 containing sulfate and chloride ions. The concrete cube specimen 3 is partially or completely immersed in the solution. The solution concentration and pH value can be precisely controlled.

[0022] The voltage adjustment range is 0-50V, and the current adjustment range is 0-5A. Electrodes are set on both sides of the concrete cube specimen 3. The ion permeation process is accelerated by applying voltage. The voltage and current are adjustable to meet different acceleration ratio requirements.

[0023] The temperature control and circulation mechanism includes a temperature control box 6, a heating and cooling device, and a humidity controller. The temperature control range is -20℃ to +80℃, and the humidity control range is 30%-95%RH. The temperature control and circulation mechanism has precise temperature control and dry-wet circulation functions, which can simulate temperature changes and humidity fluctuations in the actual environment.

[0024] The data acquisition system includes strain gauges, pressure sensors, ion concentration sensors, and a data acquisition instrument. It monitors the mechanical properties and erosion process of concrete cube specimens in real time, and automatically records and processes the data. The data acquisition instrument has 16 channels and a maximum sampling frequency of 10kHz, and can simultaneously acquire parameters such as load, strain, temperature, and concentration.

[0025] The method for using the test apparatus for simulating accelerated erosion and aging of concrete under continuous load includes the following steps: S1. Preparation of concrete cube specimen 3: First, prepare the device for continuous loading of concrete cube specimen, then put it into the corrosion liquid tank. Insert rubber rods on both sides of the standard concrete cube specimen 3 (100×100×400mm). The concrete cube specimen and the rubber rods on both sides form an isolation zone in the corrosion liquid tank, thus dividing the corrosion liquid tank 4 into two parts.

[0026] S2. Apply load: Apply a preset continuous load by loading the component.

[0027] S3. Injecting solution: Inject the prepared same type of erosion solution 8 into the space between the loaded specimen and the two sides isolated by the rubber rods in the erosion liquid tank 4. The liquid level should be flush with the top surface of the concrete cube specimen 3 but should not exceed the top surface, so that the liquid on both sides of the specimen and the rubber rods do not come into contact and are isolated from each other.

[0028] S4. Add positive and negative electrodes: Add positive and negative electrodes to both sides of the etching solution tank 4.

[0029] S5. Start the system: Turn on the point source of the positive and negative electrodes, apply an appropriate voltage, and make the positive and negative electrodes pass through the erosion solution and the concrete cube specimen to form a closed electrical circuit.

[0030] S6. Start the temperature control and circulation mechanism, set the temperature circulation program, start the data acquisition mechanism, and monitor the mechanical properties and corrosion process of the test piece in real time.

[0031] S7. Process monitoring: Regularly record parameters such as strain, load value, and solution concentration of concrete cube specimens through a data acquisition agency.

[0032] S8. Performance testing: Take out concrete cube specimens 3 at predetermined time intervals for mechanical property testing and microstructure analysis.

[0033] S9. Data Analysis: Combining experimental data and theoretical models, establish a model for predicting the aging patterns and lifespan of concrete.

[0034] Simulation tests were conducted on different parts of the dam: in the deep water area of ​​the upstream face, a high load of 0.5-0.7fc, a high concentration of corrosive solution, and a low temperature environment were used, where fc is the compressive strength of the concrete.

[0035] The water level fluctuation zone adopts medium-low load (0.2-0.4fc), dry-wet cycle and temperature change.

[0036] The atmospheric zone employs low load (0.1-0.3fc), carbonization environment, and temperature and humidity cycling.

[0037] Therefore, this invention employs the aforementioned simulated concrete accelerated erosion aging test device and method under continuous load, achieving a realistic coupling of multiple factors such as continuous load, chemical erosion, and temperature changes, thus more closely resembling the actual engineering environment. It accelerates the test process by significantly accelerating the erosion process through electrochemical means, shortening the test cycle. Parameters are precisely controllable; key parameters such as load, concentration, temperature, and voltage can be precisely controlled and adjusted. Data is comprehensive, enabling real-time monitoring of multiple parameters throughout the process, with comprehensive and accurate data acquisition. Operation is simple and flexible, with a modular design that allows for flexible configuration of test conditions according to research needs. Its application range is wide, not only suitable for aging research of concrete dams but also for durability assessment of other concrete structures.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A test apparatus for simulating accelerated erosion and aging of concrete under continuous load, characterized in that: It includes a continuous loading device and an accelerated erosion device; the continuous loading device consists of a reaction frame structure, a jack and a steel pad. The steel pad is placed between the loading head of the jack and the concrete cube specimen. The concrete cube specimen is placed at one end inside the reaction frame structure and the other end of the concrete cube specimen is placed on the jack. The accelerated erosion device consists of an erosion liquid tank, two liquid-separating rubber cylinders, positive and negative electrodes, and a power supply. The two liquid-separating rubber cylinders and the concrete cube specimen divide the erosion liquid tank into two parts. The erosion liquid tank is equipped with a temperature control and circulation mechanism and a data acquisition mechanism.

2. The test apparatus for simulating accelerated erosion and aging of concrete under continuous load according to claim 1, characterized in that: The circulating pump is located at the top of the etching solution tank, which contains an etching solution, which is either sulfate or chloride ions.

3. The test apparatus for simulating accelerated erosion and aging of concrete under continuous load according to claim 2, characterized in that: Positive and negative electrodes are placed in two independent etching solution areas separated by a concrete cube specimen and two liquid-separating rubber cylinders in the etching solution tank. The positive and negative electrodes are connected to a power source, which is connected to a current controller. Through the action of the positive and negative electrodes, the etching ions in the etching solution form a closed electrical circuit through the concrete cube specimen, resulting in a faster and more severe etching effect.

4. The test apparatus for simulating accelerated erosion and aging of concrete under continuous load according to claim 3, characterized in that: The current controller has a current adjustment range of 0-5A and a voltage adjustment range of 0-50V.

5. The test apparatus for simulating accelerated erosion and aging of concrete under continuous load according to claim 4, characterized in that: The corrosion liquid tank is connected to a temperature control and circulation mechanism, which includes a temperature control box, a heating and cooling device, and a humidity controller. The temperature control range is -20℃ to +80℃, and the humidity control range is 30%-95%RH.

6. A method for using a test apparatus for simulating accelerated erosion and aging of concrete under continuous load, comprising the test apparatus for simulating accelerated erosion and aging of concrete under continuous load as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Specimen preparation: Install the standard concrete cube specimen in the specimen station, and after installation, place it in the erosion liquid tank, ensuring that the position is centered. Insert rubber rods on both sides of the specimen. The concrete cube specimen and the rubber rods on both sides form an isolation zone inside the erosion liquid tank. S2. Applying load: Using jacks, a continuous axial load is applied to the concrete cube specimen through the reaction frame structure. After preloading and centering, the load is applied in stages to the design stress level. S3. Injecting solution: Inject the prepared same etching solution into the space on both sides of the test specimen and the space isolated by the rubber rods in the etching solution tank. The liquid level should be flush with the top surface of the test specimen to keep the liquid on both sides of the test specimen and the rubber rods from contacting each other and to isolate them. S4. Add positive and negative electrodes: Add positive and negative electrodes to both sides of the etching solution tank respectively; S5. Start the system: Turn on the power supply to the positive and negative electrodes, apply an appropriate voltage, and let the positive and negative electrodes pass through the erosion solution and the concrete cube specimen to form a closed electrical circuit; S6. Start the temperature control and circulation mechanism, set the temperature circulation program, and start the data acquisition mechanism; S7. Process monitoring: Regularly record parameters such as specimen strain, load value, and solution concentration through a data acquisition mechanism. S8. Performance testing: Take out the specimens at predetermined time intervals for mechanical property testing and microstructure analysis. S9. Data analysis: Combining experimental data and theoretical models, establish a model for predicting the aging patterns and lifespan of concrete.

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