A three-dimensional adjustable device for testing the bonding performance of special-shaped steel fibers and uhpc matrix

Abstract

The application discloses a three-dimensional adjustable special-shaped steel fiber and UHPC matrix bonding performance test device, which comprises a pulling device provided with a displacement meter, a pouring mold provided with a pouring cavity, a partition mold comprising a partition plate and an angle adjusting ball, the partition plate being installed in the pouring cavity, a plurality of through holes in a linear or matrix type being arranged on the partition plate, one angle adjusting ball being clamped in each through hole, a middle portion of each angle adjusting ball being provided with a mounting through hole for mounting a steel fiber, the angle adjusting ball being divided into two angle adjusting hemispheres along an axis of the mounting through hole, the partition plate and the angle adjusting ball being made of soft glue material, and a fixing mechanism for connecting all partition blocks of the partition plate into an integrated whole. The pouring mold of the application can pour a steel fiber concrete test piece at a time, saves time and effort, can select the number and position of the mounted steel fibers according to needs, and can adjust the angle of the steel fiber, and is not affected by the shape of the steel fiber, thereby improving test accuracy.

Description

Technical Field

[0001] This invention relates to the field of testing equipment technology, and in particular to a three-dimensional adjustable test device for the bonding performance of irregularly shaped steel fibers with UHPC matrix. Background Technology

[0002] With the vigorous development of civil engineering in my country and the continuous updating of new technologies and materials, fiber-reinforced concrete is increasingly being used in engineering construction, with steel fiber being the most commonly used fiber type. Adding steel fibers can significantly improve the shortcomings of ordinary concrete, such as easy cracking, low tensile and flexural strength, and poor toughness, while maintaining the original advantages of ultra-high performance concrete (UHPC). This makes UHPC have a wider range of application prospects in engineering. The failure of UHPC generally begins with cracking of the matrix. Numerous microcracks in the matrix are continuously initiated and propagated under stress. The three-dimensionally randomly distributed steel fibers inside the matrix act as a buffer against cracking by capturing and bridging these cracks. The magnitude of this buffering effect mainly depends on the fiber-matrix interface bonding performance and ultimately affects the flexural and tensile properties of UHPC.

[0003] To test the bond strength between steel fibers and the UHPC matrix, a steel fiber pull-out test is a necessary method. Currently, the main problems encountered in conducting pull-out tests on steel fibers are as follows:

[0004] (1) In the existing technology, the concrete matrix is ​​mainly poured in stages and sections, that is, half of the test specimen is poured first, and then the other half is poured 24 hours later, which is time-consuming and labor-intensive.

[0005] (2) Existing drawing devices mostly use single straight steel fibers to conduct drawing tests in the vertical direction or plane angle of the steel fibers. The number, angle and shape of the steel fibers are different from the situation in actual engineering where irregular steel fibers (such as hook-shaped steel fibers) are mostly used and are randomly distributed; thus, there are errors between the test data and the actual working conditions.

[0006] Therefore, there is an urgent need to design a test device that is applicable, accurate, and can effectively reflect the bonding performance between steel fibers and UHPC matrix. Summary of the Invention

[0007] The purpose of this invention is to provide a three-dimensional adjustable test device for the bonding performance between irregularly shaped steel fibers and UHPC matrix, thereby overcoming the disadvantages of time-consuming and labor-intensive casting of steel fiber reinforced concrete specimens, the inability to adjust the number and angle of steel fibers, and the limitation that only straight steel fibers can be used.

[0008] To achieve the above objectives, the present invention provides a three-dimensional adjustable test device for the bonding performance of irregularly shaped steel fibers with a UHPC matrix, comprising: a pull-out device for performing pull-out tests on steel fiber reinforced concrete specimens; a displacement gauge on the pull-out device for detecting the upward displacement of the steel fiber reinforced concrete specimens; a casting mold having a casting cavity with a front opening, the casting cavity being distributed in an I-shape; two parallel grooves distributed in the middle of the casting cavity; and a separating mold comprising a separating plate and an angle adjusting ball, the separating plate being installed in the casting cavity, and the left and right ends of the separating plate being slidably connected to the corresponding grooves; the separating plate having multiple linear or... The system comprises a matrix of through holes, each containing an angle-adjusting ball; when the through holes are linearly distributed, the partition plate divides the system into two blocks along the straight line where the centers of all the through holes are located; when the through holes are arranged in an m x n matrix, the partition plate divides the system into m+1 blocks along the straight line where the centers of all the through holes in each row are located; each angle-adjusting ball has a mounting through hole in its center for installing steel fibers, and the angle-adjusting ball is divided into two angle-adjusting hemispheres along the axis of the mounting through hole; wherein the partition plate and the angle-adjusting balls are both made of soft rubber material; and a fixing mechanism is provided to connect all the blocks of the partition plate into one unit.

[0009] Preferably, in the above technical solution, both the partition plate and the angle adjustment ball are made of silicone.

[0010] Preferably, in the above technical solution, the pulling device is provided with two clamps for fixing the steel fiber reinforced concrete specimen, and both clamps are provided with T-shaped cavities with inward openings; the T-shaped cavities correspond to the upper and lower ends of the steel fiber reinforced concrete specimen.

[0011] Preferably, in the above technical solution, the splicing surface of the two angle-adjusting hemispheres on each angle-adjusting ball has a serrated structure.

[0012] Preferably, in the above technical solution, the fixing mechanism includes fixing pinholes and metal pins. The end of the partition plate is provided with a plurality of fixing pinholes spaced apart along its length direction, and each fixing pinhole is fixed by the metal pin.

[0013] Preferably, in the above technical solution, the diameters of both ends of the metal needle are larger than the diameter of the fixing needle hole.

[0014] Preferably, in the above technical solution, the metal needle passes through the partition plate and the angle adjustment ball respectively.

[0015] Preferably, in the above technical solution, the rear side of the casting cavity is provided with a demolding air hole.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The casting cavity of the casting mold of this invention has an opening on the front side. After setting a partition mold in the middle, it is possible to cast I-shaped steel fiber reinforced concrete specimens in one go, saving time and effort. The partition mold is provided with multiple through holes for installing angle adjustment balls. The number and position of steel fibers can be selected as needed, and the angle of the steel fibers can be adjusted by rotating the angle adjustment balls. If the angle adjustment balls do not have steel fibers installed, the splicing surface of the angle adjustment balls only needs to be rotated into the partition plate to facilitate subsequent casting. Because the angle adjustment ball includes two angle adjustment hemispheres, it is not only convenient to disassemble the angle adjustment ball later, but also can be directly clamped in the middle of the steel fiber when installing steel fibers, regardless of the shape of the steel fiber. That is, the shape of the steel fiber can be various shapes, which can effectively simulate the characteristics of steel fibers with irregular shapes and random distribution in concrete matrix in actual working conditions, thus improving the accuracy of the test.

[0018] 2. Using the test apparatus of the present invention, the two ends of the steel fiber reinforced concrete specimen are T-shaped. The clamp of the pull-out device is provided with a T-shaped cavity corresponding to the steel fiber reinforced concrete specimen, so that the clamp does not directly contact the steel fiber, but transmits the tensile force to the steel fiber through the concrete. This can better simulate the longitudinal pull-out condition of concrete, reduce test errors, and make the test data more accurate.

[0019] 3. The separator and angle adjustment ball of the present invention are both made of silicone, which has the advantages of not being easily deformed at room temperature, softening when heated, being lightweight, being made of common materials, being easy to customize, and being inexpensive. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the steel fiber reinforced concrete specimen mounted on a pull-out device in the three-dimensional adjustable irregular steel fiber and UHPC matrix bonding performance test device according to the present invention.

[0021] Figure 2 This is a schematic diagram of a partition plate of a partition mold according to the present invention, on which multiple angle adjustment balls are installed in a straight line.

[0022] Figure 3 It is based on the present invention Figure 2 A schematic diagram of the partition plate in the diagram.

[0023] Figure 4 It is based on the present invention Figure 3 A schematic diagram of the structure in which the two partitions of the middle partition are set apart.

[0024] Figure 5 This is a schematic diagram of a partition plate of a partition mold according to the present invention, on which multiple angle-adjustable balls are installed in a matrix distribution.

[0025] Figure 6 It is based on the present invention Figure 5 A schematic diagram of the structure in which the angle adjustment ball rotates to different positions in the middle section.

[0026] Figure 7 It is based on the present invention Figure 5 A schematic diagram of the structure in which the angle adjustment ball rotates to different positions.

[0027] Figure 8 It is based on the present invention Figure 5 A schematic diagram of the partition plate in the diagram.

[0028] Figure 9 It is based on the present invention Figure 8 A schematic diagram of the structure in which the three partitions of the middle partition are set apart.

[0029] Figure 10 This is a schematic diagram of the angle adjustment ball according to the present invention.

[0030] Figure 11 This is a schematic diagram of the structure for casting steel fiber reinforced concrete specimens in a casting mold according to the present invention.

[0031] Explanation of key figure labels:

[0032] 1-Clamping device, 2-Pulling device, 3-Steel fiber reinforced concrete specimen, 4-Separator plate, 401-Block, 402-Through hole, 5-Angle adjusting ball, 501-Installation through hole, 502-Serrated structure, 6-Fixing pinhole, 7-Concrete, 8-Steel fiber, 9-Pouring mold. Detailed Implementation

[0033] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0034] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0035] Figures 1 to 11 A schematic diagram of a three-dimensional adjustable shaped steel fiber bonding performance testing device to a UHPC matrix according to a preferred embodiment of the present invention is shown. The testing device includes a pull-out device 2, a casting mold 9, a separating mold, and a fixing mechanism. (Reference) Figures 1 to 11The pull-out device 2 is used to perform pull-out tests on the steel fiber reinforced concrete specimen 3. The pull-out device 2 is equipped with a displacement gauge to detect the upward displacement of the steel fiber reinforced concrete specimen 3. The casting mold 9 has a front-opening casting cavity, which is arranged in an I-shape to ensure the cast steel fiber reinforced concrete specimen 3 has an I-shaped structure. Two parallel grooves are provided in the middle of the casting cavity to facilitate the installation of the partition plate 4. With the partition plate 4 in the middle, the I-shaped steel fiber reinforced concrete specimen 3 can be cast in one go, saving time and effort. The partition mold includes a partition plate 4 and an angle adjusting ball 5. The partition plate 4 is installed in the casting cavity, and its left and right ends are slidably connected to the corresponding grooves to secure it within the cavity. The partition plate 4 has multiple through holes 402 arranged in a straight line or matrix. Each through hole 402 contains an angle adjusting ball 5, which can rotate within the corresponding through hole 402 to adjust the angle of the steel fibers 8. When the through holes 402 are arranged in a straight line, the partition plate 4 is divided into two partition blocks 401 along the straight line where the centers of all the through holes 402 are located, to facilitate the installation and removal of the partition plate 4. When the through holes 402 are arranged in a matrix of m rows and n columns, the partition plate 4 is divided into m+1 partition blocks 401 along the straight line where the centers of all the through holes 402 in each row are located, to facilitate the installation and removal of the partition plate 4. Here, m and n are both integers greater than or equal to 2. Each angle adjustment ball 5 has a mounting through hole 501 in its center for installing steel fibers 8, and the angle adjustment ball 5 is divided into two angle adjustment hemispheres along the axis of the mounting through hole 501 to facilitate the installation of steel fibers 8 and subsequent removal of the angle adjustment ball 5. Both the partition plate 4 and the angle adjustment ball 5 are made of soft rubber material, which facilitates their removal after casting. The fixing mechanism is used to connect all the partitions 401 of the partition plate 4 into one piece, so that the partition plate 4 can play a separating role and fix the angle adjusting ball 5 at the required angle, preventing the angle adjusting ball 5 from rotating during the pouring process. Using the test device of this invention, the partition mold is provided with multiple through holes 402 for installing the angle adjusting ball 5. The number and position of the steel fibers 8 can be selected as needed, and the angle of the steel fibers 8 can be adjusted by rotating the angle adjusting ball 5. If the angle adjusting ball 5 does not have steel fibers 8 installed, it is only necessary to rotate the splicing surface of the angle adjusting ball 5 into the partition plate 4 to facilitate subsequent pouring. Because the angle adjusting ball 5 includes two angle adjusting hemispheres, it is not only convenient to disassemble the angle adjusting ball 5 later, but also can be directly clamped in the middle of the steel fibers 8 when installing them, unaffected by the shape of the steel fibers 8. That is, the shape of the steel fibers 8 can be various shapes, which can effectively simulate the characteristics of steel fibers 8 using irregularly shaped steel fibers and randomly distributed in the concrete matrix 7 in actual working conditions, improving the accuracy of the test.

[0036] refer to Figures 2 to 10The partition plate 4 and the angle adjusting ball 5 can be made of materials such as silicone, polyurethane, or rubber, so that the partition plate 4 and the angle adjusting ball 5 have the advantages of not being easily deformed at room temperature, softening when heated, and being elastic. Preferably, both the partition plate 4 and the angle adjusting ball 5 are made of silicone, which has the advantages of not being easily deformed at room temperature, softening when heated, being elastic, lightweight, being a common material, being easy to customize, and being inexpensive, so as to facilitate the subsequent disassembly of the partition plate 4 and the angle adjusting ball 5.

[0037] refer to Figure 1 The pull-out device 2 can be an electronic universal testing machine, which includes a chassis, a base, a crossbeam, and a hydraulic tensioning device. To facilitate the installation of the steel fiber reinforced concrete specimen 3, the pull-out device 2 preferably has two clamps 1 for fixing the steel fiber reinforced concrete specimen 3. Each clamp 1 has an inward-facing T-shaped cavity, so that the T-shaped cavities of the two clamps 1 form an I-shape, and the T-shaped cavities correspond to the upper and lower ends of the steel fiber reinforced concrete specimen 3, thus facilitating the installation of the specimen. The front and / or rear sides of the T-shaped cavities are open; when installing the steel fiber reinforced concrete specimen 3, it is only necessary to insert the specimen 3 into the upper and lower T-shaped cavities from the front-to-back direction. The upper clamp 1 is connected to the crossbeam, the crossbeam is connected to the chassis via the hydraulic tensioning device, and the lower clamp 1 is mounted on the base. Through the action of the hydraulic tensioning device, a pull-out test can be performed on the steel fiber reinforced concrete specimen 3 within the clamps 1.

[0038] refer to Figure 10 The splicing surface of the two angle-adjusting hemispheres can be a planar structure or a structure with interlocking concave and convex surfaces. Preferably, on each angle-adjusting ball 5, the splicing surface of the two angle-adjusting hemispheres is a serrated structure 502 that interlocks, which can prevent the angle-adjusting hemispheres from being misaligned and improve the connection performance.

[0039] refer to Figures 2 to 9The fixing mechanism can be a structure of clamps and connecting rods, or a structure of fixing pinholes 6 and metal needles. Preferably, the fixing mechanism includes fixing pinholes 6 and metal needles. Multiple spaced fixing pinholes 6 are provided at the ends of the partition plate 4 along its length, and each fixing pinhole 6 penetrates all partitions 401. Each fixing pinhole 6 is fixed by a metal needle, thereby tightly connecting all partitions 401 together and forming a seamless partition plate 4, allowing the partition plate 4 to function as a separator during subsequent pouring; and allowing the angle adjusting ball 5 to be tightly connected to the through hole 402 of the partition plate 4, preventing the angle adjusting ball 5 from rotating, and thus fixing the steel fiber 8 at the required angle. To facilitate the fixing of the metal needles and the angle adjusting ball 5, it is further preferred that the diameters of both ends of the metal needle are larger than the diameter of the fixing pinholes 6, so that the metal needle has a structure that is large at both ends and small in the middle, facilitating the fixing of the metal needle. Furthermore, the metal needles passing through the partition plate 4 and the angle adjusting ball 5 respectively can further improve the fixing effect of the angle adjusting ball 5. Preferably, each angle adjusting ball 5 is fixed by two metal needles.

[0040] refer to Figure 11 To facilitate demolding, the casting mold 9 can be detachable, or it can have demolding air holes. Preferably, the casting cavity has demolding air holes on the rear side, and when demolding is required, air can be pumped through the demolding air holes using an air gun to demold.

[0041] refer to Figures 1 to 11In use, select the number and position of steel fibers 8 according to the test requirements. Take out the angle adjustment balls 5 that need to be installed with steel fibers 8, separate the two angle adjustment hemispheres and clamp them in the middle of the steel fibers 8. Place the partition plate 4 vertically, and then put the angle adjustment balls 5 into the corresponding through holes 402. Rotate the angle adjustment balls 5 to rotate the steel fibers 8 to the required angle. Repeat this process until the steel fibers 8 are installed in the required position and adjusted to the required angle. If there are still angle adjustment balls 5 without steel fibers 8 installed, rotate the splicing surface of the angle adjustment ball 5 into the partition plate 4 to prevent concrete slurry 7 from flowing into the angle adjustment balls 5 through the installation through holes 501. Then, use metal needles to tightly connect all the partitions 401 and angle adjustment balls 5 to connect all the partitions 401 and angle adjustment balls 5 into one unit, thereby fixing the angle adjustment balls 5 at the required angle. Before pouring concrete, apply a release agent to the surface of the partition plate 4 and the surface of the angle adjustment balls 5 to facilitate subsequent demolding operations. Then, the partition plate 4 is installed in the groove of the pouring cavity, dividing the I-shaped pouring cavity into two symmetrical T-shaped cavities. The two T-shaped cavities are then poured simultaneously through the front opening of the pouring cavity. The concrete 7 is poured slowly to prevent the angle of the steel fibers 8 from being affected by the concrete 7 during pouring. After the concrete 7 has completely solidified, it is demolded by air injection through the demolding air hole using an air gun, thus obtaining the steel fiber reinforced concrete specimen 3. Then, the metal needle connection is released, and the spacers 401 are pulled out one by one. Next, the angle adjusting ball 5 is softened with hot water, and the angle adjusting hemispheres are removed one by one. After removing all the spacers 401 and angle adjusting balls 5, the steel fiber reinforced concrete specimen 3 is installed on the upper and lower clamps 1 of the pull-out device 2, and a pull-out test is performed on the steel fibers 8.

[0042] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A three-dimensional adjustable test device for the bonding performance of irregularly shaped steel fibers to a UHPC matrix, characterized in that, include: A pull-out device is used to perform pull-out tests on steel fiber reinforced concrete specimens; the pull-out device is equipped with a displacement gauge to detect the upward displacement of the steel fiber reinforced concrete specimens. A casting mold has a casting cavity with a front opening, and the casting cavity is distributed in an I-shape; the middle of the casting cavity has two parallel grooves distributed from left to right. A dividing mold includes a dividing plate and angle-adjusting balls. The dividing plate is installed inside the casting cavity, and its left and right ends are slidably connected to corresponding grooves. The dividing plate has multiple through holes arranged in a straight line or matrix, and each through hole contains an angle-adjusting ball. When the through holes are arranged in a straight line, the dividing plate is divided into two blocks along the straight line where the centers of all the through holes are located. When the through holes are arranged in a matrix of m rows and n columns, the dividing plate is divided into m+1 blocks along the straight line where the centers of all the through holes in each row are located. Each angle-adjusting ball has a mounting through hole in its center for installing steel fibers, and the angle-adjusting ball is divided into two angle-adjusting hemispheres along the axis of the mounting through hole. Both the dividing plate and the angle-adjusting balls are made of soft rubber material. A fixing mechanism for connecting all the partitions of the partition plate into one unit.

2. The three-dimensional adjustable irregular-shaped steel fiber and UHPC matrix bonding performance test device according to claim 1, characterized in that, Both the partition plate and the angle adjustment ball are made of silicone.

3. The three-dimensional adjustable irregular-shaped steel fiber and UHPC matrix bonding performance testing device according to claim 1, characterized in that, The pulling device is equipped with two clamps for fixing the steel fiber reinforced concrete specimen, and both clamps are provided with T-shaped cavities with inward openings; the T-shaped cavities correspond to the upper and lower ends of the steel fiber reinforced concrete specimen.

4. The three-dimensional adjustable irregular-shaped steel fiber and UHPC matrix bonding performance testing device according to claim 1, characterized in that, On each of the angle-adjusting spheres, the splicing surface of the two angle-adjusting hemispheres has a serrated structure.

5. The three-dimensional adjustable irregular-shaped steel fiber bonding performance test device to UHPC matrix according to claim 1, characterized in that, The fixing mechanism includes fixing pin holes and metal pins. The end of the partition plate is provided with a plurality of fixing pin holes spaced apart along its length direction, and each fixing pin hole is fixed by the metal pin.

6. The three-dimensional adjustable shaped steel fiber and UHPC matrix bonding performance testing device according to claim 5, characterized in that, The diameters at both ends of the metal needle are larger than the diameter of the fixing needle hole.

7. The three-dimensional adjustable irregular-shaped steel fiber and UHPC matrix bonding performance testing device according to claim 5, characterized in that, The metal needles pass through the partition plate and the angle adjustment ball, respectively.

8. The three-dimensional adjustable irregular-shaped steel fiber and UHPC matrix bonding performance testing device according to claim 1, characterized in that, The casting cavity is provided with a demolding air hole on the rear side.

Images