An apparatus and method for testing the bond properties of inorganic fiber-concrete

Abstract

The application discloses a kind of test device and method for testing the bonding performance of inorganic fiber-concrete, the device includes anchoring section, the skeleton for maintaining loading process fiber axial tension, mold, baffle and displacement sensor;The middle part of the baffle is provided with a hole, a plurality of inorganic fibers are inserted in the hole, the concrete is poured in the space surrounded by the mold and the baffle, the two ends of the inorganic fibers are embedded in the concrete, and the mold is removed after the concrete hardens to make the baffle complete debonding;The displacement sensor is used to monitor the strain condition of inorganic fiber.The method is implemented based on the above test device.The application has the advantages of simple structure, easy operation, high testing precision, etc.

Description

Technical Field

[0001] This invention mainly relates to the field of material testing technology in civil engineering, specifically to a test device and method for testing the bonding performance of inorganic fiber-concrete. Background Technology

[0002] Concrete, primarily used in engineering structures for bearing pressure, is insufficient to meet the demands of complex dynamic scenarios in civil engineering, such as impact and earthquake resistance. Adding appropriate amounts of fiber to cementitious materials can significantly improve the flexural toughness of concrete, increase its tensile and flexural strength, and delay the initiation and development of cracks.

[0003] In existing technologies, the aforementioned fiber-reinforced concrete primarily relies on the addition of steel fibers. However, steel fibers are costly to produce, energy-intensive, and release large amounts of greenhouse gases. Replacing steel fibers with low-carbon and environmentally friendly inorganic fibers such as basalt fibers to reinforce cement-based materials is an inevitable trend.

[0004] The bonding performance of traditional inorganic fibers is a key indicator of their toughening effect on concrete. Most current pull-out devices are based on steel fiber designs, which offer limited control over fiber alignment during testing. Because steel fibers are multi-directional isotropic materials, alignment errors in pull-out tests have little impact on the results. However, inorganic fibers only possess high strength in the unidirectional tensile direction, making them highly susceptible to breakage at the anchoring end. Further development of more advanced testing devices is needed to ensure proper alignment of inorganic fibers during pull-out testing and prevent fiber breakage. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a test device and test method for testing the bonding performance of inorganic fiber-concrete, which is simple in structure, easy to operate, and has high testing accuracy, in response to the technical problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A test apparatus for testing the bond performance of inorganic fibers to concrete includes an anchoring section, a skeleton for maintaining the axial tension of the fibers during loading, a mold, a partition, and a displacement sensor. The partition has a hole in its center, into which several inorganic fibers are inserted. Concrete is poured into the space enclosed by the mold and the partition, with both ends of the inorganic fibers embedded in the concrete. After the concrete hardens, the mold is removed to allow the partition to detach. The displacement sensor is used to monitor the strain of the inorganic fibers.

[0008] As a further improvement to the device of the present invention: the frame includes thin steel plates at both ends and pins that are vertically distributed at the four corners, and the connection is tight and sufficient.

[0009] As a further improvement of the device of the present application: the steel sleeve and the steel rod are smooth.

[0010] As a further improvement of the device of the present application: the steel sleeve and the steel rod are smooth.

[0011] As a further improvement of the device of the present application: the steel sleeve and the steel rod are smooth.

[0012] As a further improvement of the device of the present application: the steel sleeve and the steel rod are smooth.

[0013] As a further improvement of the device of the present application: the steel sleeve and the steel rod are smooth.

[0014] As a further improvement of the device of the present application: the steel sleeve and the steel rod are smooth.

[0015] The present application further provides a testing method based on the above-mentioned testing device for testing the bonding performance of inorganic fiber-concrete, which comprises the following steps:

[0016] Step S1: Assemble the prefabricated skeleton for maintaining axial tension of the fiber during the loading process through the nut, and then connect the anchoring segment to form a force-bearing whole.

[0017] Step S2: According to the number of fibers to be tested, open holes on the partition plate, the size of the hole in the middle partition plate corresponds to the diameter of the fiber and is fitted into the skeleton, which is used to determine the centering position of the fiber, assemble the plug and embed it in the mold to facilitate the pouring of concrete.

[0018] Step S3: After the concrete hardens, remove the mold, debond the end partition plates and remove them, and debond the middle partition plate.

[0019] Step S4: Connect the anchoring segment to the universal testing machine to obtain the loading force, and ensure the lateral stiffness of the device without affecting the inorganic fiber pull-out through the plug design of the skeleton, monitor the fiber strain through the displacement sensor, and test the bonding strength and stress-strain relationship of the fiber.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] 1. The test device and method for testing the bonding performance of inorganic fiber-concrete of the present application have simple structure, easy operation and high testing precision, so as to make up for the defects that the traditional fiber pull-out test device cannot ensure that the pulling directions of the two ends of the fiber remain the same horizontal line.

[0022] 2. The test device and method for testing the bonding performance of inorganic fiber-concrete of the present application are simple to assemble and easy to operate, greatly improve the centering operation of the fiber pull-out test, ensure the experimental effect that the fiber is pulled out vertically to the matrix, prevent the fiber from being broken during the installation process and the pulling process of the test piece, and improve the precision and test efficiency of the pulling test. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural principle schematic diagram of the device in a specific application example of the present application.

[0024] Figure 2 is a structural principle schematic diagram of the skeleton in a specific application example of the present application.

[0025] Figure 3 is a structural principle schematic diagram of the steel plug of the skeleton structure in a specific application example of the present application.

[0026] Figure 4 is a structural principle schematic diagram of the anchoring section that can be clamped in a specific application example of the present application.

[0027] Figure 5 is a structural principle schematic diagram of the local embedding of the PVC partition plate into the mold in a specific application example of the present application.

[0028] LEGEND:

[0029] 1, anchoring section; 2, skeleton; 3, mold; 4, partition plate. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below in combination with the drawings and specific examples of the present application.

[0031] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0032] In addition, the terms "first", "second", etc. are used only for descriptive purposes and should not be construed as implying or suggesting relative importance or an indicated number of the technical features indicated. Thus, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0033] In the present application, unless otherwise explicitly specified and limited, the terms "assembly", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

[0034] As shown in Figures 1-5 The test device for testing the bonding performance of inorganic fiber-concrete of the present application includes a clamped anchoring section 1, a stiff skeleton 2 for maintaining the axial tension of the fiber during the loading process, a mold 3 (such as a cast iron mold), a partition plate 4 (such as an embedded PVC partition plate), and a displacement sensor. The embedded PVC partition plate 4 has a hole in the middle, and a plurality of inorganic fibers are inserted into the hole. The mold 3 and the partition plate 4 are poured with concrete in the space surrounded by the mold 3 and the partition plate 4. The two ends of the inorganic fibers are embedded in the concrete. After the concrete hardens, the mold 3 is removed, and the partition plate 4 is debonded.

[0035] In a specific application example, the skeleton 2 is a stiff skeleton, which includes thin steel plates at both ends and steel pins vertically distributed at the four corners, which are connected tightly and sufficiently to improve the lateral stiffness of the device during the pulling process, and can ensure the centering of the entire device during the pulling test, without affecting the strain of the fiber during the entire process.

[0036] Further, in a specific application example, the pin includes a steel sleeve and a steel rod. In actual application, the difference between the inner diameter of the sleeve and the diameter of the steel rod is strictly controlled, and the surface of the steel rod and the inner wall of the sleeve are smooth, and there should not be too much gap between them. In actual application, the friction can be reduced by brushing lubricating oil, so as to only provide lateral stiffness and not affect the test data.

[0037] Further, in a specific application example, the anchoring holes for the steel bolt on the thin steel plate are arranged in a rectangular array, and an anchoring hole for clamping the anchoring segment is arranged at the center position, facilitating assembly. In a specific application, the position of the anchoring hole needs to consider the number of test fibers, and an anchoring hole for clamping the anchoring segment is arranged at the center position. In the assembly process, the anchoring segment should be anchored first, and then the steel bolt is assembled, so as to minimize the deformation of the steel bolt caused by collision.

[0038] Further, in a specific application example, the steel bolt is locally protruded near the tail end to ensure that the thin steel plates at both ends of the stiff skeleton 2 and the steel bolt are vertically and equidistantly distributed, facilitating the anchoring connection of the nut, preventing uneven stress on the stiff skeleton 2, and causing experimental errors.

[0039] As a preferred example, the anchoring segment 1 in the application is a clamping anchoring segment, and the anchoring segment 1 adopts a rectangular end that is connected to the stiff skeleton 2 and has a circular thread on one side and a clamping side on the other side. A frosted pattern is added to the rectangular surface to facilitate the connection of the stiff skeleton 2 and increase the mechanical engagement between the clamp and the universal testing machine, thereby better obtaining the tensile load.

[0040] As a preferred example, the mold 3 is designed with four embedded grooves, which are distributed by four PVC partitions 4, and three spaces are arranged for pouring concrete at both ends and placing fibers in the middle, so as to reduce the steps of mold assembly and disassembly. The fiber opening position of the partition 4 corresponds to ensure that the fiber is always embedded vertically.

[0041] The application further provides a test method for testing the bonding performance of inorganic fibers-concrete, which is based on the above-mentioned test device, and the process includes:

[0042] Step S1: Assemble the prefabricated stiff skeleton for maintaining the axial tension of the fiber during loading by the nut, and then connect the clamping anchoring segment to form a force whole;

[0043] Step S2: According to the number of fibers to be tested, the holes are opened in the PVC partition in advance, the size of the hole in the middle PVC partition should correspond to the diameter of the fiber and be fitted into the stiff skeleton, used to determine the fiber centering position, assemble the bolt and embed the mold to facilitate the pouring of concrete, and minimize the error of test data;

[0044] Step S3: After the concrete hardens, the mold is removed, the two end PVC partitions are debonded and removed, and the middle PVC partition only needs to be debonded;

[0045] Step S4: the loading force is obtained by connecting the claspable anchoring segment with the universal testing machine, the lateral stiffness of the device is ensured without affecting the fiber pull-out by the bolt design of the rigid skeleton, the fiber strain condition is monitored by the displacement sensor, and the bonding strength and stress-strain relationship of the fiber are tested.

[0046] The above are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solutions falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall be considered as the protection scope of the present application.

Claims

1. A test apparatus for testing the bond performance of inorganic fiber-concrete, characterized in that, The system includes an anchoring section, a frame for maintaining axial tension of the fibers during loading, a mold, partitions, and displacement sensors. The frame comprises thin steel plates at both ends and steel pins vertically distributed at the four corners. Each pin consists of a steel sleeve and a steel rod, with the surface of the steel rod and the inner wall of the sleeve being smooth. Anchoring openings for the steel pins are provided on the thin steel plates, arranged in a rectangular array, with an anchoring hole at the center for clamping the anchoring section. The thin steel plates at both ends are connected by the steel pins. The mold has four embedding grooves, and the partitions are inserted into these grooves to separate the mold. The mold is arranged in a pattern, creating three spaces for pouring concrete at both ends and placing fibers in the middle. Thin steel plates at both ends are placed in the two spaces for pouring retarded concrete. A hole is opened in the middle of the partition plate, and several inorganic fibers are inserted into the hole. The positions of the fiber openings on the partition plate are aligned so that the embedding of inorganic fibers is always in a vertical state. Concrete is poured into the space enclosed by the mold and the partition plate, and the two ends of the inorganic fibers are embedded in the concrete. After the concrete hardens, the mold is removed to detach the partition plate. The displacement sensor is used to monitor the strain of the inorganic fibers.

2. The test apparatus for testing the bond performance of inorganic fiber-concrete according to claim 1, characterized in that, The pin protrudes locally near its tail end to ensure that the thin steel plates and steel pins at both ends of the frame are vertically and equidistantly distributed.

3. The test apparatus for testing the bond performance of inorganic fiber-concrete according to claim 1 or 2, characterized in that, The anchoring section is a clampable anchoring section. The anchoring section adopts a rectangular end that transitions from a circular thread connected to the skeleton to the clamping side, and has a frosted texture on the rectangular surface.

4. A test method for a test apparatus for testing the bond performance of inorganic fiber-concrete according to any one of claims 1-3, characterized in that, include: Step S1: Assemble the prefabricated skeleton to maintain the axial tension of the fibers during the loading process using nuts, and then connect it with the anchoring section to form a whole bearing structure; Step S2: According to the number of fibers to be tested, make holes in the partition plate. The size of the holes in the middle partition plate should match the diameter of the fibers and correspond to it. Then fit it into the skeleton to determine the centering position of the fibers, assemble the pins and embed them into the mold to facilitate the pouring of concrete. Step S3: After the concrete has hardened, remove the mold, detach the end plates and remove them, and detach the middle plate. Step S4: The loading force is obtained by connecting the anchor section to the universal testing machine. The lateral stiffness of the device is ensured by the pin design of the skeleton without affecting the pull-out of the inorganic fiber. The fiber strain is monitored by the displacement sensor, and the bonding strength and stress-strain relationship of the fiber are tested.

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