A kind of embedded FRP grid strip concrete test block making device

Abstract

The utility model relates to a kind of FRP grid strip concrete test block making device embedded, belong to building engineering technical field, including the mould of upper opening, FRP grid is inserted in the inside of mould, and the both ends of FRP grid are fixedly connected with mould by fixed rope ring;Strip steel sheet is also inserted in mould, and strip steel sheet is vertically arranged, and FRP grid passes through strip steel sheet.It is realized that FRP grid is accurately positioned and stably fixed in mould, break through the limitation that existing mode can only paste FRP sheet on the surface of test block, and the concrete test block embedded with FRP grid can be prepared;Meanwhile, the cooperation of strip steel sheet and FRP grid can simulate the state that FRP grid is embedded in the inside of concrete in actual engineering, so that test block can truly reflect the synergistic effect of FRP grid and concrete under engineering scene, and provide test block carrier in conformity with test demand for studying crack suppression mechanism of embedded FRP grid.

Description

Technical Field

[0001] This utility model relates to the field of building engineering technology, and in particular to a device for making concrete test blocks with embedded FRP grids and joints. Background Technology

[0002] In large-volume concrete structures such as bridges and dams, temperature cracks often appear on the surface due to the large amount of heat released by cement in its early stages. Over time, these cracks exposed to air significantly shorten the service life of the concrete structure. To mitigate cracking caused by early-age temperature gradients in large-volume concrete, fiber-reinforced composite (FRP) meshes are typically embedded within the large-volume concrete structure.

[0003] To study the crack suppression mechanism of FRP grid concrete, concrete specimens are usually prepared for fracture mechanics tests. Existing methods for preparing concrete specimens (such as publication number CN206990364U) typically involve first preparing concrete specimens with pre-reserved gaps, and then fixing FRP sheets to the surface of the concrete specimens with epoxy resin, symmetrically distributed on both sides of the gaps.

[0004] The above-mentioned method of preparing concrete test blocks involves pasting FRP sheets onto the surface of the test block, which cannot produce concrete test blocks with embedded FRP meshes. Therefore, it cannot be used to study the crack suppression mechanism of concrete with embedded FRP meshes. Furthermore, in existing practical engineering projects, FRP meshes are mostly embedded inside the concrete structure to enhance performance. Test blocks obtained by the existing preparation method cannot effectively simulate actual engineering scenarios. Utility Model Content

[0005] To address the technical problems in the existing preparation method of bonding FRP sheets to the surface of test blocks, which cannot produce concrete test blocks with embedded FRP mesh, cannot be used to study the crack inhibition mechanism of concrete with embedded FRP mesh, and cannot effectively simulate actual engineering scenarios, this utility model provides a device for making concrete test blocks with embedded FRP mesh and joints.

[0006] The technical solution of this utility model is as follows: This invention provides a device for fabricating concrete specimens with embedded FRP mesh and joints. The device includes a mold with an open top, into which an FRP mesh is inserted. The two ends of the FRP mesh are fixedly connected to the mold via fixing rope loops. A slotted steel sheet is also inserted into the mold, vertically positioned, through which the FRP mesh passes. This device achieves precise positioning and stable fixation of the FRP mesh within the mold, overcoming the limitation of existing methods that only allow FRP sheets to be pasted onto the surface of the specimen. It enables the fabrication of concrete specimens with embedded FRP mesh. Furthermore, the interaction between the slotted steel sheet and the FRP mesh simulates the state of the FRP mesh embedded within concrete in actual engineering projects, allowing the specimen to realistically reflect the synergistic effect between the FRP mesh and concrete in engineering scenarios. This provides a specimen carrier that meets experimental requirements for studying the crack inhibition mechanism of embedded FRP mesh.

[0007] Preferably, the slotted steel sheet has slits that extend vertically and penetrate the bottom of the steel sheet, through which the FRP mesh passes. This vertically extending, bottom-penetrating slit design not only facilitates the smooth insertion and rapid positioning of the FRP mesh through the slotted steel sheet, but also ensures that the FRP mesh remains vertically flat and without displacement during concrete pouring, preventing deviations in test block performance from actual engineering results due to FRP mesh distortion or misalignment. Simultaneously, the slits allow for precise control of the relative position of the FRP mesh and the slotted steel sheet.

[0008] Preferably, the length of the gap is less than the length of the slotted steel sheet, which allows the top of the slotted steel sheet to form a complete seamless section. This section can play a positioning and supporting role during concrete pouring, and the seamless section can prevent a large amount of concrete slurry from seeping into the top of the gap, ensuring the integrity of the precast crack shape. Preferably, the width of the gap is not less than the thickness of the FRP mesh. This ensures that the FRP mesh can pass smoothly through the gap, preventing it from being scratched or deformed during installation. It also reduces the gap between the gap and the mesh, preventing excessive grout from seeping into the gap during concrete pouring and affecting the accuracy of the precast cracks. At the same time, a reasonable gap width allows the FRP mesh to fit tightly against the slotted steel sheet, ensuring the stability of the FRP mesh within the test block and providing a precise structural basis for studying the inhibitory effect of the FRP mesh on crack propagation.

[0009] Preferably, the width of the slotted steel sheet is smaller than the width of the mold, which ensures that there is enough space between the slotted steel sheet and the inner wall of the mold for pouring concrete, and ensures that the concrete on both sides of the slotted steel sheet is connected as one piece, rather than completely separated.

[0010] Preferably, the length of the slotted steel sheet is greater than the depth of the mold, which facilitates the quick removal of the slotted steel sheet after the concrete is poured and initially set, reduces disturbance to the test block, ensures the integrity of the precast crack morphology, and the protruding part can serve as an operating handle for the slotted steel sheet, making it convenient for installation and positioning, and improving the construction efficiency of test block preparation.

[0011] Preferably, a pointed tip is fixed on one side of the slotted steel sheet, extending along the length of the slotted steel sheet. The pointed tip on the slotted steel sheet can form a sharp groove on the inner side of the precast crack, accurately replicating the tip shape of the natural crack in the real concrete structure, so that the crack of the test block has real stress concentration characteristics. Compared with the blunt reserved gap in the existing method, this design can more accurately simulate the mechanical environment of crack initiation and propagation in actual engineering, ensuring that the parameters such as fracture toughness and crack propagation rate measured by fracture mechanics test are true and reliable.

[0012] Preferably, a slot is provided on one inner wall of the mold. The slot is vertically positioned, and the side of the slotted steel sheet away from the tip is inserted into the slot. This enables rapid positioning and fixation of the slotted steel sheet, effectively preventing lateral displacement of the slotted steel sheet during concrete pouring and ensuring the accurate position of the precast crack within the test block. At the same time, the slot can limit the shaking of the slotted steel sheet, ensuring its relative position with the FRP mesh is stable, further improving the structural consistency of test blocks in the same batch and avoiding test errors caused by inaccurate mold positioning.

[0013] As can be seen from the above technical solutions, the advantages of this utility model are: 1. FRP mesh and slotted steel sheets are set inside the mold, which can produce concrete test blocks with embedded FRP mesh. At the same time, the combination of slotted steel sheets and FRP mesh can simulate the state of FRP mesh embedded in concrete in actual engineering. This allows the test block to truly reflect the synergistic effect between FRP mesh and concrete in engineering scenarios, and provides a test block carrier that meets the experimental requirements for studying the crack inhibition mechanism of embedded FRP mesh.

[0014] 2. A pointed tip is fixed on one side of the slotted steel sheet. The pointed tip on the slotted steel sheet can form a sharp groove on the inner side of the precast crack, accurately replicating the tip shape of the natural crack in the real concrete structure, so that the crack of the test block has real stress concentration characteristics. Compared with the blunt reserved gap in the existing method, this design can more accurately simulate the mechanical environment of crack initiation and propagation in actual engineering, and ensure that the parameters such as fracture toughness and crack propagation rate measured by fracture mechanics test are true and reliable.

[0015] 3. A slot is provided on one inner wall of the mold. The slot is set vertically, and the side of the slotted steel sheet away from the tip is inserted into the slot. This realizes the rapid positioning and fixation of the slotted steel sheet, effectively preventing the slotted steel sheet from shifting laterally during concrete pouring, and ensuring the accurate position of the precast crack in the test block. At the same time, the slot can limit the shaking of the slotted steel sheet, ensuring its relative position with the FRP mesh is stable, further improving the structural consistency of the test blocks in the same batch, and avoiding test errors caused by inaccurate mold positioning. Attached Figure Description

[0016] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the embedded FRP grid jointed concrete test block fabrication device according to one or more embodiments of the present invention (perspective of the left side of the mold). Figure 2 This is a schematic diagram of the front view structure of the slotted steel sheet according to one or more embodiments of the present invention; Figure 3 This is a side view structural diagram of the slotted steel sheet according to one or more embodiments of the present invention; Figure 4 This is a top view of the embedded FRP mesh seamed concrete test block according to one or more embodiments of the present invention. Figure 5 This is a partially enlarged structural diagram of the mold slot location according to one or more embodiments of the present invention; The components represented by the various reference numerals in the diagram are: 1. FRP mesh; 2. Slotted steel sheet; 3. Mold; 4. Fixing rope loop; 5. Gap; 6. Tip; 7. Specimen body; 8. Precast crack; 9. Slot. Detailed Implementation

[0018] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0019] Example 1 In a typical embodiment of this utility model, such as Figures 1-5As shown, a device for fabricating a concrete specimen with embedded FRP mesh and joints is proposed, comprising: an FRP mesh 1, a jointed steel sheet 2, a mold 3, and fixing rope rings 4. The mold 3 has an open top structure, and fixing holes are provided at both ends of the mold 3 for installing the fixing rope rings 4. The FRP mesh 1 is inserted into the mold 3 and arranged along the length of the mold 3. The two ends of the FRP mesh 1 are fixedly connected to the fixing rope rings 4 at both ends of the mold 3, thereby fixing the position of the FRP mesh 1 inside the mold 3. The jointed steel sheet 2 is vertically inserted into the mold 3, and the FRP mesh 1 passes through the jointed steel sheet 2. The jointed steel sheet 2 is perpendicular to the FRP mesh 1. The jointed steel sheet 2 is used to prepare and form prefabricated cracks 8 on the specimen body 7.

[0020] In this embodiment, the mold 3 is a rectangular mold. Two fixing holes are opened at both ends of the mold 3. The two fixing holes at the same end are arranged vertically opposite each other. A fixing rope ring 4 is installed in each fixing hole to fix and limit the vertical position of the two ends of the FRP mesh 1.

[0021] FRP mesh 1 is a mesh structure made of fiber reinforced composite material. FRP mesh 1 is placed inside mold 3. Two fixing rope loops 4 are fixedly connected to mold 3 at both ends of FRP mesh 1. FRP mesh 1 is parallel to the side of mold 3.

[0022] In this embodiment, the aperture of the FRP mesh 1 is larger than the particle size of the concrete to ensure that the concrete can pass through the FRP mesh 1 smoothly and to ensure an effective fixed connection between the FRP mesh 1 and the test block body 7; the height of the FRP mesh 1 is not greater than the depth of the mold 3.

[0023] The slotted steel sheet 2 is inserted into the mold 3, and the slotted steel sheet 2 is perpendicular to the FRP mesh 1. The FRP mesh 1 passes through the slotted steel sheet 2, such as... Figure 2 and Figure 3 As shown, a slot 5 is provided on the slotted steel sheet 2. The slot 5 extends along the length of the slotted steel sheet 2, that is, the slot 5 extends vertically. The slot 5 penetrates the bottom of the slotted steel sheet 2, and the length of the slot 5 is less than the length of the slotted steel sheet 2. The FRP mesh 1 passes through the slot 5.

[0024] The length of the slotted steel sheet 2 is greater than the depth of the mold 3. Specifically, in this embodiment, the length of the slotted steel sheet 2 is 150mm and the depth of the mold 3 is 100mm, so as to reserve a pull-out position to facilitate pulling the slotted steel sheet 2 out of the mold 3.

[0025] The width of the slotted steel sheet 2 is smaller than the width of the mold 3 to ensure that the concrete on both sides of the slotted steel sheet 2 is connected as one and not completely separated; the width of the gap 5 is not less than the thickness of the FRP mesh 1.

[0026] like Figure 3 As shown, a pointed tip 6 is fixedly provided on one side of the slotted steel sheet 2. The pointed tip 6 extends along the length of the slotted steel sheet 2. In this embodiment, the pointed tip 6 is located on the front side of the slotted steel sheet 2 so that a sharp groove is formed on the inner side of the prefabricated crack 8. This not only facilitates the extraction of the slotted steel sheet 2, but also simulates the tip effect of a real crack, matching the essential requirements of fracture mechanics testing.

[0027] like Figure 5 As shown, in order to better limit the position of the slotted steel sheet 2, a slot 9 is also provided on one side of the inner wall of the mold 3. The slot 9 is set vertically, and the side of the slotted steel sheet 2 away from the tip 6 (i.e. the rear side of the slotted steel sheet 2) is inserted into the slot 9 of the mold 3. At the same time, the FRP mesh 1 passes through the gap 5 on the slotted steel sheet 2. Thus, through the cooperation of the FRP mesh 1 and the slot 9, the position of the slotted steel sheet 2 is effectively limited, which facilitates its use.

[0028] The specific working principle is as follows: First, cut the FRP mesh 1 to the specified size and place the cut FRP mesh 1 in the mold 3. Thread nylon ropes through the fixing holes at both ends of the mold 3, and pass the nylon ropes through the FRP mesh 1 and tie them into knots to form fixing rope loops 4, so as to fix the FRP mesh 1 and the mold 3 together. Then, apply lubricating oil to the surface of the slotted steel sheet 2, insert the slotted steel sheet 2 into the mold 3, so that the FRP mesh 1 passes through the gap 5 on the slotted steel sheet 2, the side of the slotted steel sheet 2 with the tip 6 faces the inside of the mold 3, and the other side of the slotted steel sheet 2 is inserted into the slot 9 of the mold 3 to limit the position of the slotted steel sheet 2. Pour concrete into mold 3, and after the concrete has initially set, pull out the slotted steel strip 2. Figure 4 As shown, a prefabricated crack 8 is formed on the main body 7 of the test block, passing through the FRP mesh 1. In this embodiment, the height ratio (crack height ratio) of the prefabricated crack 8 to the main body 7 of the test block is 0.2-0.5. After 24 hours, the fixing rope ring 4 was cut, and the main body 7 of the test block with embedded FRP mesh 1 was demolded. The demolded test block was then transferred to a constant temperature and humidity curing chamber for curing.

[0029] Understandably, after the concrete is poured, it should be vibrated if necessary. After the concrete is poured, a film should be placed over the opening at the top of mold 3 as needed. The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for fabricating concrete test blocks with embedded FRP mesh, comprising: The mold (3) with an opening at the top is characterized in that an FRP mesh (1) is inserted inside the mold (3), and the two ends of the FRP mesh (1) are fixedly connected to the mold (3) by a fixing rope ring (4); a slotted steel sheet (2) is also inserted inside the mold (3), the slotted steel sheet (2) is set vertically, and the FRP mesh (1) passes through the slotted steel sheet (2).

2. The device for fabricating concrete test blocks with embedded FRP mesh according to claim 1, characterized in that, A slot (5) is provided on the slotted steel sheet (2). The slot (5) extends vertically and penetrates the bottom of the slotted steel sheet (2). The FRP mesh (1) passes through the slot (5).

3. The device for fabricating concrete test blocks with embedded FRP mesh according to claim 2, characterized in that, The length of the gap (5) is less than the length of the slotted steel sheet (2).

4. The device for fabricating concrete test blocks with embedded FRP mesh according to claim 2, characterized in that, The width of the gap (5) is not less than the thickness of the FRP mesh (1).

5. The device for fabricating concrete test blocks with embedded FRP mesh according to claim 1, characterized in that, The width of the slotted steel sheet (2) is smaller than the width of the mold (3).

6. The device for fabricating concrete test blocks with embedded FRP mesh according to claim 1, characterized in that, The length of the slotted steel sheet (2) is greater than the depth of the mold (3).

7. The device for fabricating concrete test blocks with embedded FRP mesh according to claim 1, characterized in that, A pointed tip (6) is fixed on one side of the slotted steel sheet (2), and the pointed tip (6) extends along the length direction of the slotted steel sheet (2).

8. The apparatus for fabricating concrete test blocks with embedded FRP mesh according to claim 7, characterized in that, A slot (9) is provided on one side of the inner wall of the mold (3). The slot (9) is set vertically, and the side of the slotted steel sheet (2) away from the tip (6) is inserted into the slot (9).

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