Device and method for testing the tensile load deformation of a fiber reinforced cementitious material

Abstract

This invention discloses a testing device and method for tensile deformation of fiber-reinforced cementitious materials, belonging to the field of engineering material testing technology. The testing device mainly includes three parts: a support frame, a lever system, and a specimen mounting system. The main steps of the testing method include: lifting the lever to unload; installing the specimen mounting system, slowly releasing the lever and finely adjusting the position of the tensile specimen to reduce eccentricity and achieve preloading; repeatedly lifting and unloading the lever, and finely adjusting the centering tensile clamp and the tensile specimen; installing the displacement sensor and zeroing it in the unloaded state; adjusting the weight of the lever according to the real-time display value of the force sensor to complete the suspension and precise loading of the tensile specimen. This method applies tensile force to the cement-based composite material through the lever mechanism and performs arbitrary crack propagation evaluation based on the micro-cracks in the cement-based material using digital image processing, which can quantitatively characterize the creep deformation and crack propagation process of cement-based composite materials under continuous tensile load.

Description

Technical Field

[0001] This invention belongs to the field of engineering material testing technology, and specifically discloses a device and method for testing the tensile deformation of fiber-reinforced cementitious materials. Background Technology

[0002] Concrete, as a typical quasi-brittle engineering material, is highly susceptible to cracking under the combined effects of complex loads and natural environments. Harmful media can seep into the concrete along the cracks, causing problems such as steel corrosion and structural deterioration, seriously affecting the service life and safety performance of concrete structures. To improve the crack resistance of concrete, fibers are commonly incorporated into cement-based materials in engineering practice. The bridging effect of fibers inhibits the initiation and propagation of cracks. Among them, high-performance fiber-reinforced cement-based materials can exhibit multi-fine cracking and strain hardening characteristics under uniaxial tension, with an ultimate tensile strain of over 0.5% and fine crack width controlled below 100μm, significantly improving the ductility and impermeability durability of the structure.

[0003] Quantitatively assessing the creep and cracking behavior of fiber-reinforced cementitious composites under uniaxial tension is of great significance for the scientific research and practical engineering application of this material. However, the research on quantitative monitoring methods for creep and crack propagation of fiber-reinforced cementitious composites under continuous load is relatively limited at home and abroad, and the existing testing methods have obvious shortcomings: (1) Most existing creep testing devices for cement-based materials are designed for compressive creep, and there is a lack of dedicated testing devices for tensile creep of fiber-reinforced cement-based materials; (2) Existing long-term deformation measurement methods for cement-based materials can only test the overall deformation within the gauge length range, and cannot quantitatively characterize the entire process of local cracks from initiation to failure during the load-bearing process. Summary of the Invention

[0004] Technical problem solved: In view of the technical problems existing in the background technology, the present invention provides a device and method for testing the tensile deformation of fiber-reinforced cementitious materials. Through the lever structure, different levels of continuous tensile load can be applied to the tensile specimen. Combined with displacement sensor and digital image processing technology, the overall deformation of the gauge length of the material and the propagation process of each crack can be quantitatively recorded and analyzed, so as to realize high-precision, quantitative and long-term monitoring of the tensile deformation of fiber-reinforced cementitious materials.

[0005] Technical solution: The present invention provides a tensile load deformation testing device for fiber-reinforced cementitious materials, comprising a support frame, a lever system, a specimen mounting system, a digital camera, and a displacement sensor; The support frame is composed of support frame columns, support frame top beams, support frame bottom beams, and several reaction force connecting plates connected together; the reaction force connecting plates are perpendicular to the support frame bottom beam on one side of the support frame and extend outwards; The lever system includes a roller shaft and several levers; the roller shaft is positioned above the reaction connection plate and its two ends are fixedly connected to the support frame columns, and a space is reserved between the roller shaft and the top beam of the support frame at its top for the installation or rotation of the levers; the levers are rotatably connected to the roller shaft according to the loading ratio, and each lever has two ends used to hang a counterweight and a tensile specimen, respectively, and the counterweight is connected to the lever through a flexible suspension cable; The specimen mounting system includes a force sensor, a connecting buckle, a tensile clamp, and a tensile specimen, which are connected and suspended between the lever and the reaction connecting plate in sequence; the tensile specimen is an uncracked specimen or a pre-cracked specimen. The digital camera is positioned on one side of the tensile specimen, and the displacement sensor is positioned on the gauge length of the tensile specimen. The digital camera and displacement sensor are used to measure the deformation of the gauge length of the specimen and record the crack propagation process on the specimen surface.

[0006] Preferably, the support frame columns, support frame top beams, support frame bottom beams, and reaction connection plates are made of I-beams, angle steel, or steel pipes, and their cross-sectional dimensions are determined according to the load-bearing level and stiffness requirements; the support frame top beam at the end corresponding to the specimen mounting system is covered with a buffer sponge pad.

[0007] Preferably, the roller is a multi-cylinder structure, including a mandrel and multiple sleeves fitted on it, the number of sleeves matching the number of specimens to be suspended; the sleeves are fixedly connected to the levers, and bearings are installed inside the sleeves and can rotate around the mandrel, the two ends of the mandrel are fixedly connected to the support frame columns.

[0008] Preferably, the force sensor is an electronic hanging scale, the force sensor is connected to the tensile clamp, and the force sensor monitors the tensile force value of the tensile specimen in real time.

[0009] Preferably, the digital camera is equipped with a macro lens, and the single-pixel precision of the images captured by the digital camera reaches the micrometer level, which is used to perform quantitative analysis of crack propagation in tensile specimens in combination with digital image processing technology; The displacement sensor is connected to the gauge length of the specimen via a support, and is used to test the displacement of the gauge length with a measurement accuracy down to the micrometer level.

[0010] Preferably, the tensile specimen is a dog-bone-shaped fiber-reinforced cementitious material specimen; the pre-cracked specimen is a fiber-reinforced cementitious material specimen with pre-cracked under tension.

[0011] Preferably, both ends of the reaction connecting plate and the lever are provided with connecting rings for mounting flexible suspension cables, force sensors or tensile clamps, and the two connecting rings connected to the force sensor and tensile clamp are located on the same vertical line to ensure that the tensile specimen is subjected to force in the vertical direction.

[0012] The present invention also discloses a method for testing the tensile load-bearing deformation of fiber-reinforced cementitious materials using the above-mentioned device, comprising the following steps: Step 1: Raise the loading end of the lever to unload the lever; Step 2: Suspend the force sensor, connecting buckle, tensile clamp and tensile specimen in sequence at the loaded end of the lever; Step 3: Connect the tensile clamp to the reaction plate using the connecting buckle to complete the initial loading of the tensile specimen; slowly release the lever and finely adjust the position of the tensile specimen to reduce eccentricity, and slowly release the lever to achieve preloading; Step 4: Repeatedly raise and lower the lever, and finely adjust the centering tension clamp and the tension specimen; Step 5: Install the displacement sensor on the gauge length section of the tensile specimen and zero the displacement sensor under unloaded conditions; Step 6: Based on the real-time display value of the force sensor, adjust the mass of the counterweight on the other side of the lever to complete the suspension and precise loading of the tensile specimen.

[0013] Preferably, the specific observation steps for tensile specimens are as follows: (1) For uncracked specimens, the deformation values ​​of different loading times under the gauge length segment are directly read by displacement sensors to characterize the tensile creep behavior of the material; (2) For pre-cracked specimens, images of cracks on the specimen surface are captured by macro photography components, and digital image processing technology is used to perform pixel-level quantitative characterization of cracks and analyze the crack propagation process.

[0014] Preferably, the test method is suitable for testing the tensile creep behavior of uncracked specimens and the crack propagation process of cracked specimens, and can be extended to coupled tests in corrosive solution environments. By extending the corrosive solution box module, load-environment coupling tests can be realized. For quantitative characterization of cracks in pre-cracked specimens, the average crack width is calculated by statistically analyzing the crack width at the intersection of equally spaced parallel reference lines and the crack, and the average crack width development curves are plotted under different load durations.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention fills the gap in quantitative testing methods for creep and crack propagation of fiber-reinforced cementitious materials under sustained tensile load, and provides a dedicated tensile-load-bearing deformation testing device, solving the problem that existing devices are mostly designed for compressive creep and lack the ability to test tensile creep. 2. The device of the present invention applies a continuous tensile load using the lever principle, and achieves precise control of the tensile force by combining a force sensor. Moreover, the structural dimensions of the device can be flexibly set according to the test requirements, adapting to tensile specimens of different specifications and tensile loads of different levels, and has strong versatility. 3. The method of this invention, in conjunction with displacement sensors, macro photography, and digital image processing technology, enables dual testing of fiber-reinforced cementitious materials: the displacement sensor obtains the micron-level precision deformation value of the gauge length of the uncracked specimen to characterize the tensile creep behavior of the material; the macro photography and digital image processing methods achieve high-precision quantitative characterization of fine cracks of about 50μm at the micron level, and completely record the entire process of crack initiation and propagation. 4. The structural design of the device of the present invention takes into account both test accuracy and test safety. By setting the connecting rings on the same vertical line, the eccentric force on the tensile specimen is eliminated, ensuring the accuracy of test data. The top beam of the support frame is covered with a buffer sponge pad to provide buffering for the lever, preventing the lever from violently impacting the support frame after the tensile specimen breaks, thus ensuring the safety of test operation. 5. The method of this invention has clear steps and is highly operable. Furthermore, by expanding the erosion solution box module, it can realize the material performance testing under the coupled action of load and environment, providing comprehensive and accurate experimental data support for the scientific research and engineering application of fiber-reinforced cementitious materials. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the testing device and observation structure of the present invention; Figure 2 for Figure 1 Schematic diagram of the assembly structure of the pilot specimen mounting system; Figure 3 Images showing the crack propagation process of pre-cracked specimens with different load holding times in embodiments of the present invention; Figure 4 This is a curve showing the average crack width development of the pre-cracked specimen in an embodiment of the present invention.

[0017] Reference numerals: 1. Support frame column; 2. Support frame top beam; 3. Support frame bottom beam; 4. Reaction connecting plate; 5. Roller; 501. Sleeve; 502. Mandrel; 6. Lever; 7. Connecting ring; 8. Flexible suspension cable; 9. Counterweight; 10. Force sensor; 11. Connecting buckle; 12. Tensile clamp; 13. Tensile specimen; 14. Tripod; 15. Digital camera; 16. Recognition area; 17. Displacement sensor. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings. Figures 1-4 The technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0019] This invention uses engineered cementitious composites (ECC) as the test object, which can exhibit strain hardening under tensile load. In this invention, typical ECC specimens are cured to a specified age, stretched to 1% strain to pre-crack, and the crack propagation process of the pre-cracked ECC specimens under continuous tensile load is observed when the bearing capacity is adjusted to 80% of the pre-crack peak stress.

[0020] Example 1: As Figures 1-2 As shown, this invention discloses a tensile deformation testing device for fiber-reinforced cementitious materials, including a support frame, a lever system, a specimen mounting system, a digital camera 15 equipped with macro photography components, and a displacement sensor 17. By applying a continuous tensile load through the lever principle, and combining the displacement sensor and digital image processing technology, it is possible to achieve tensile creep testing of uncracked specimens and quantitative characterization of crack propagation in pre-cracked specimens.

[0021] like Figure 1 As shown, the support frame is welded together from four support frame columns 1, four support frame top beams 2, four support frame bottom beams 3, and three reaction connection plates 4. The overall dimensions of the support frame are determined based on the total height of the force sensor, tensile clamp, tensile specimen, lever length, and the number of specimens to be mounted. The reaction connection plate 4 extends outward from the support frame bottom beam 3 on one side of the support frame, and is used to connect the specimen mounting system. The support frame top beam 2 at the end corresponding to the specimen mounting system is covered with a cushioning sponge pad, which provides buffering and blocking for the lever after the tensile specimen breaks, ensuring test safety. The support frame columns 1, support frame top beams 2, support frame bottom beams 3, and reaction connection plates 4 are made of I-beams, angle steel, or steel pipes, and their cross-sectional dimensions are determined according to the load-bearing level and stiffness requirements, with appropriate allowance to ensure the structural stability of the support frame.

[0022] like Figures 1-2As shown, the lever system includes a roller 5 and several levers 6. The roller 5 is positioned above the reaction connecting plate 4 and its two ends are fixedly connected to the support frame column 1. Space is reserved between the roller 5 and the top beam 2 of the support frame at its top for the installation or rotation of the levers. The levers are single H-beams. The levers 6 are rotatably connected to the roller 6 according to the loading ratio (e.g., 1:5). Each lever 6 has a counterweight 9 and a tensile specimen 13 mounted at both ends, respectively. The counterweight 9 is connected to the lever 6 through a connecting ring 7 and a flexible cable 8 set on the long end of the lever. The weight of the counterweight is converted into a tensile force on the tensile specimen by utilizing the lever principle, thereby achieving the application of a continuous tensile load. Specifically, the roller 5 is a multi-cylinder structure, including a mandrel 502 and multiple sleeves 501 mounted on it. The number of sleeves 501 matches the number of test specimens to be suspended. The sleeves are fixedly connected to the lever 6. The sleeves are made of metal that is easy to weld to the lever of the I-beam. The sleeves 501 are equipped with bearings and can rotate around the mandrel 502. The two ends of the mandrel 502 are fixedly connected to the support frame column 1. The fixed point is close to the top beam of the support frame and provides enough rotation space for the lever so that the lever can rotate freely around the roller.

[0023] The specimen mounting system includes a force sensor 10, a connecting buckle 11, a tensile clamp 12, and a tensile specimen 13, which are sequentially connected and suspended between a lever 6 and a reaction connecting plate 4. The tensile specimen is either an uncracked specimen or a pre-cracked specimen; the tensile specimen 13 is a dog-bone-shaped fiber-reinforced cementitious material specimen; the pre-cracked specimen is a fiber-reinforced cementitious material specimen with pre-existing cracks after tensile testing. Connecting rings 7 are provided at both ends of the lever 6 and on the reaction connecting plate 4 for mounting the flexible suspension cable 8, the force sensor 10, or the tensile clamp 12. The two connecting rings 7 connected to the specimen mounting system are located on the same vertical line to ensure that the tensile specimen is subjected to force in the vertical direction, avoiding the influence of eccentric force on the test results. The force sensor 10 can be an electronic hanging scale. The force sensor is connected to the tensile clamp and can detect the tensile force value of the tensile specimen in real time, facilitating precise adjustment of the counterweight mass. Tension specimens were selected from dog bone-like fiber-reinforced cementitious materials. After curing to a specified age, they were stretched to 1% strain to pre-crack, which was used to test the tensile creep behavior and crack propagation process of the material.

[0024] A digital camera 15 is detachably connected to a tripod 14 and positioned on one side of the tension specimen. Equipped with a macro lens, the camera 15 captures images with a single-pixel precision down to the micrometer level (3.6 micrometers), clearly capturing microcracks on the surface of the tension specimen. This is used in conjunction with digital image processing technology (Chinese Patent 202210424484.7) to evaluate microcracks in cement-based materials within the tension specimen, enabling quantitative assessment of crack propagation at any location and stage. A displacement sensor 17 is positioned correspondingly within the gauge length of the tension specimen. Connected to the gauge length via a support, the sensor achieves micrometer-level accuracy, directly reading the displacement of the gauge length to characterize the tensile creep deformation of the uncracked specimen.

[0025] This invention fills the gap in quantitative testing methods for creep and crack propagation under sustained tensile loads in fiber-reinforced cementitious materials. It provides a dedicated tensile deformation testing device, solving the problem that existing devices primarily target compressive creep and lack tensile creep testing capabilities. The device applies sustained tensile loads using a lever principle, combined with a force sensor for precise control of the tensile force. Furthermore, the device's structural dimensions can be flexibly configured according to experimental requirements, adapting to different specifications of tensile specimens and varying levels of tensile loads, demonstrating strong versatility. The device's structural design balances experimental accuracy and safety. By aligning the connecting rings on the same vertical line, eccentric forces on the tensile specimen are eliminated, ensuring the accuracy of experimental data. A buffer sponge pad covers the top beam of the support frame, providing cushioning for the lever and preventing violent impact on the support frame after the tensile specimen breaks, thus ensuring safe experimental operation.

[0026] Example 2: The present invention also discloses a method for testing the tensile load-bearing deformation of fiber-reinforced cementitious materials using the above-mentioned device, comprising the following steps: (1) Raise the loading end (long end of the lever) of lever 6 to put the lever in an unloaded state.

[0027] (2) Suspend the force sensor 10, the connecting buckle 11, the tensile clamp 12 and the pre-cracked ECC specimen in sequence below the load end (short end) of the lever 6.

[0028] (3) Connect the tensile clamp 12 to the reaction force connecting plate 4 through the connecting buckle 11 to complete the initial loading of the tensile specimen 13; slowly loosen the lever (long end) and finely adjust the position of the tensile specimen 13 to reduce eccentricity, and slowly loosen the lever to achieve preloading.

[0029] (4) Repeatedly raise and unload lever 6, finely adjust and precisely center the tensile clamp 12 and the pre-cracked ECC specimen to eliminate eccentric force.

[0030] (5) Install the displacement sensor 17 in the gauge length section of the pre-cracked ECC specimen and zero the displacement sensor under the lever unloading state.

[0031] (6) Based on the real-time display value of the force sensor 10, adjust the mass of the counterweight 9 on the other side of the lever 6 until the tensile force reaches 80% of the pre-crack peak stress, complete the precise loading of the tensile specimen 13, and realize the application of continuous tensile load.

[0032] The tensile specimen 13 that completed the test was observed and tested. The specific steps were as follows: Crack images of the surface of the pre-cracked ECC specimen under different holding times were captured by a digital camera with a macro photography component (e.g., Figure 1 Identify region 16 and Figure 3 As shown in the figure, digital image processing technology (Chinese Patent 202210424484.7) is used to perform pixel-level quantitative characterization of cracks and analyze the crack propagation process. The crack width at the intersection of three equally spaced parallel reference lines with the crack is statistically analyzed, and the average crack width is calculated. The average crack width development curves under different load durations are plotted (e.g., Figure 4 As shown in the figure, this method enables quantitative characterization of the crack propagation process in ECC specimens, providing experimental data for the engineering application of high-ductility cement-based composite materials.

[0033] The testing method of this invention is applicable to testing the tensile creep behavior of uncracked specimens and the crack propagation process of cracked specimens. It can also be extended for coupled testing in corrosive solution environments by expanding the corrosive solution chamber module to achieve load-environment coupled testing. This invention, in conjunction with displacement sensors, macro photography, and digital image processing technology, achieves dual testing of fiber-reinforced cementitious materials: displacement sensors acquire micron-level precision deformation values ​​of the gauge length of uncracked specimens to characterize the tensile creep behavior of the material; macro photography and digital image processing methods achieve high-precision quantitative characterization of fine cracks around 50 μm at the micron level, completely recording the entire process of crack initiation and propagation. The method is clear in its steps, highly operable, and can be extended with the corrosive solution chamber module to achieve material performance testing under load-environment coupled action, providing comprehensive and accurate experimental data support for the scientific research and engineering applications of fiber-reinforced cementitious materials.

[0034] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A device for testing the tensile deformation of fiber-reinforced cementitious materials, characterized in that, Includes a support frame, lever system, specimen mounting system, digital camera (15) and displacement sensor (17); The support frame is composed of support frame columns (1), support frame top beams (2), support frame bottom beams (3) and several reaction force connecting plates (4); the reaction force connecting plates (4) are perpendicular to the support frame bottom beams (3) on one side of the support frame and extend outward; The lever system includes a roller (5) and several levers (6); the roller (5) is set above the reaction connection plate (4) and its two ends are fixedly connected to the support frame column (1). The roller (5) and the support frame top beam (2) at its top are reserved for the installation or rotation of the levers; the levers (6) are rotatably connected to the roller according to the loading ratio. Each lever (6) is used to hang a counterweight (9) and a tensile test piece (13) at both ends. The counterweight (9) is connected to the lever (6) through a flexible suspension cable (8). The specimen mounting system includes a force sensor (10), a connecting buckle (11), a tension clamp (12), and a tension specimen (13), which are connected and suspended between the lever (6) and the reaction connecting plate (4) in sequence; the tension specimen is an uncracked specimen or a pre-cracked specimen; The digital camera (15) is positioned on one side of the tensile specimen, and the displacement sensor (17) is positioned on the gauge length of the tensile specimen. The digital camera (15) and the displacement sensor (17) are used to measure the deformation of the gauge length of the specimen and record the crack propagation process on the surface of the specimen.

2. The tensile load deformation testing device for fiber-reinforced cementitious materials according to claim 1, characterized in that, The supporting frame columns (1), supporting frame top beams (2), supporting frame bottom beams (3) and reaction connection plates (4) are made of I-beams, angle steel or steel pipes, and their cross-sectional dimensions are determined according to the bearing capacity and stiffness requirements; the supporting frame top beams (2) at the end corresponding to the specimen mounting system are covered with buffer sponge pads.

3. The tensile load deformation testing device for fiber-reinforced cementitious materials according to claim 1, characterized in that, The roller (5) is a multi-cylinder structure, including a mandrel (502) and multiple sleeves (501) fitted on it. The number of sleeves (501) matches the number of test specimens to be suspended. The sleeves are fixedly connected to the lever (6), and the sleeves (501) are equipped with bearings and can rotate around the mandrel (502). The two ends of the mandrel (502) are fixedly connected to the support frame column (1).

4. The tensile load deformation testing device for fiber-reinforced cementitious materials according to claim 1, characterized in that, The force sensor (10) is an electronic hanging scale. The force sensor (10) is connected to the tensile clamp (12). The force sensor monitors the tensile force value of the tensile specimen in real time.

5. The tensile load deformation testing device for fiber-reinforced cementitious materials according to claim 1, characterized in that, The digital camera (15) is equipped with a macro lens, and the single pixel precision of the image captured by the digital camera (15) reaches the micrometer level, which is used to perform quantitative analysis of crack propagation of tensile specimens in combination with digital image processing technology. The displacement sensor (17) is connected to the gauge length of the specimen via a support. It is used to test the displacement of the gauge length with a measurement accuracy of micrometer level.

6. The tensile load deformation testing device for fiber-reinforced cementitious materials according to claim 1, characterized in that, The tensile specimen (13) is a dog bone-shaped fiber-reinforced cementitious material specimen; the pre-cracked specimen is a fiber-reinforced cementitious material specimen with pre-cracked under tension.

7. The tensile load deformation testing device for fiber-reinforced cementitious materials according to claim 1, characterized in that, Both ends of the reaction connection plate (4) and lever (6) are provided with connecting rings (7) for installing flexible suspension cable (8), force sensor (10) or tensile clamp (12), and the two connecting rings (7) connected to the force sensor (10) and tensile clamp (12) are located on the same vertical line to ensure that the tensile specimen is subjected to force in the vertical direction.

8. A method for testing the tensile-load-bearing deformation of fiber-reinforced cementitious materials using the apparatus described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Raise the loading end of lever (6) to unload lever (6); Step 2: Suspend the force sensor (10), connecting buckle (11), tension clamp (12) and tension specimen (13) in sequence at the load end of the lever (6). Step 3: Connect the tensile clamp (12) and the reaction connection plate (4) through the connecting buckle (11) to complete the initial loading of the tensile specimen (13); slowly loosen the lever and finely adjust the position of the tensile specimen (13) to reduce eccentricity, and slowly loosen the lever to achieve preloading; Step 4: Repeatedly raise and unload the lever (6), and finely adjust the centering tension clamp (12) and the tension specimen (13). Step 5: Install the displacement sensor (17) on the gauge length section of the tensile specimen (13) and zero the displacement sensor in the unloaded state; Step 6: Based on the real-time display value of the force sensor (10), adjust the mass of the counterweight (9) on the other side of the lever (6) to complete the suspension and precise loading of the tensile specimen (13).

9. The method for testing the tensile deformation of fiber-reinforced cementitious materials according to claim 8, characterized in that, The specific observation steps for the tensile specimen (13) are as follows: (1) For uncracked specimens, the deformation values ​​of different loading duration sub-gauge segments are directly read by displacement sensor (17) to characterize the tensile creep behavior of the material; (2) For pre-cracked specimens, images of cracks on the specimen surface are captured by macro photography components, and digital image processing technology is used to perform pixel-level quantitative characterization of cracks and analyze the crack propagation process.

10. The method for testing the tensile deformation of fiber-reinforced cementitious materials according to claim 9, characterized in that, The test method is applicable to testing the tensile creep behavior of uncracked specimens and the crack propagation process of cracked specimens, and can be extended to coupled tests in corrosive solution environments. By extending the corrosive solution box module, load-environment coupling tests can be realized. For quantitative characterization of cracks in pre-cracked specimens, the average crack width is calculated by statistically analyzing the crack width at the intersection of equally spaced parallel reference lines and the crack, and the average crack width development curves are plotted under different load durations.

Images