A mortar tensile bonding strength detection tool

Abstract

The present application relates to a kind of mortar tensile adhesive strength detection frock, belong to detection frock technical field.The present application includes rack, loading mechanism is equipped on the rack, loading mechanism has the driving output end that can be up and down active, the driving output end of loading mechanism is connected with the pull head for the adhesive test block on the layer of mortar to be examined, rack is further equipped with the lower pull mechanism for the substrate cement mortar block on test block is pulled down, further include connecting seat and connecting piece, connecting seat is connected on the driving output end of loading mechanism;Connecting piece is horizontally spaced and is equipped with multiple groups, connecting piece includes the slider at top, each slider is slid along vertical direction and is arranged on connecting seat, connecting seat is equipped with the limiting step with the upper and lower stop of slider below slider, the height position of each limiting step is different.The present application can make the detection result of mortar tensile adhesive strength more accurate in the detection mode of once pulling of multiple test pieces.

Description

Technical Field

[0001] This invention relates to the field of testing tooling technology, and in particular to a tooling for testing the tensile bond strength of mortar. Background Technology

[0002] Tensile bond strength of mortar is a key indicator for evaluating the bonding performance between mortar and the substrate, directly affecting the reliability and safety of the connection between the building finish layer and the wall. This indicator reflects the bonding ability of the mortar at the interface with the base layer after hardening, and is an important guarantee to ensure that thin-layer structures such as external insulation systems and facing bricks do not experience common quality defects such as hollowing and detachment during long-term use. Accurately measuring the tensile bond strength of mortar is of great significance in building engineering quality inspection, product development, and production quality control. The test results not only provide technical evidence to verify whether the material performance meets relevant national standards, but also provide data support for optimizing construction processes, thereby effectively avoiding engineering hazards caused by bonding failure.

[0003] Currently, the tensile bond strength of mortar is typically tested using a pull-out testing machine. During testing, a base cement mortar block is prepared, a molding frame is placed on the block, and the mortar to be tested is filled and pressed into the frame. After the specimen has initially hardened, the molding frame is removed, the surface of the mortar is sanded, and a layer of high-strength epoxy adhesive is applied to the bottom of the pull-out head. The pull-out head is then pressed onto the mortar surface, and the base cement mortar block with the pull-out head attached is placed into the lower clamp of the testing machine. The pull-out head is connected to the upper clamp of the machine, and the upper clamp is moved away from the lower clamp to pull the specimen apart. The testing machine automatically records the maximum force at which the specimen breaks.

[0004] With the increasing demand for testing efficiency, pull-out testing machines that can simultaneously measure multiple samples have emerged on the market. These machines can perform pull-out tests on multiple mortar blocks on the same large substrate at the same time, and take the average value of the test results of multiple blocks as the test result, which effectively improves testing efficiency and accuracy.

[0005] For example, the patent disclosed in patent CN211478033U, which discloses a testing tool for the tensile bond strength of adhesive mortar, has the following core technical solution: it includes an operating platform, a longitudinal guide rail, a transverse guide rail, a mortar block fixing component, several sensors, sensor clamps, a main controller, and a slider. The mortar block fixing component is fixed on the operating platform. The longitudinal guide rail is set on the columns on both sides of the operating platform. The slider is installed on the longitudinal guide rail, and a transverse guide rail is set on the slider. The main controller is installed on the transverse guide rail and slides along the transverse guide rail. Several sensors are evenly distributed and connected below the middle of the main controller. A sensor clamp is connected below each sensor. The main controller adjusts the position of the sensors by sliding the transverse and longitudinal guide rails.

[0006] This solution has the advantages of being able to test the tensile bond strength of multiple bonding mortars at once, improving work efficiency, ensuring consistent test verticality, and providing good data uniformity.

[0007] However, in actual testing, the fracture times of the various test blocks are not completely synchronized. Due to the material uniformity, molding quality, and subtle differences in the bonding interface of the mortar test blocks, they often fracture successively at different points in a short period within the same batch of tests. When the first test block fractures, it suddenly separates from the substrate, and the pull-out force applied to it is instantly released, generating a certain amount of mechanical vibration. This vibration is transmitted to the entire testing system through rigid connecting components such as the equipment frame and substrate.

[0008] For subsequent test blocks that have not yet broken, their detection sensors are in a state of force detection. The vibration generated by the first broken test block will be superimposed on the detection signals of these sensors, forming mechanical interference and electrical signal noise. This vibration interference causes abnormal fluctuations in the force detection curve of the subsequently broken test block, making it difficult for the sensors to accurately capture the true peak tensile force. Especially when multiple test blocks break sequentially, the vibration generated by each initial break will accumulate and affect the detection process of all subsequent unbroken test blocks, causing the tensile force detection values ​​of subsequent test blocks to deviate from the true value, resulting in data deviation or excessive dispersion, which seriously affects the accuracy and reliability of the test results. Summary of the Invention

[0009] This invention provides a tooling for testing the tensile bond strength of mortar, in order to solve the technical problem of low reliability of test results in existing mortar tensile bond strength testing equipment that can test multiple test blocks simultaneously.

[0010] To solve the above problems, the present invention provides a mortar tensile bond strength testing fixture with the following technical solution: A fixture for testing the tensile bond strength of mortar includes a frame, a loading mechanism on the frame, a drive output end capable of vertical movement, a pull-out head connected to the drive output end of the loading mechanism for bonding the mortar layer to be tested on a test block, and a pull-down mechanism on the frame for pulling down the base cement mortar block on the test block. The fixture also includes: The connector is attached to the drive output of the loading mechanism. The connector is provided in multiple sets at horizontal intervals. The connector includes a slider, and each slider slides vertically through the connector seat. The connector seat is provided with a limiting step below each slider to limit the downward sliding stroke of the slider. When each connector is not subjected to external force, the vertical distance between the slider and the corresponding limiting step is different.

[0011] By employing the above technical solution, different vertical distances are maintained between the sliders and the limiting steps, ensuring that each slider contacts the limiting step sequentially during the upward movement of the connecting seat. Each specimen then begins to bear tensile force according to the height of the limiting step. This staggered loading design effectively prevents all specimens from reaching the critical fracture state simultaneously, dispersing fracture events that might otherwise be concentrated in the same time period along the timeline. When one specimen fractures, the mechanical vibration generated by the earlier fracture significantly reduces interference with the detection signals of other specimens currently in critical stress stages, as their stress stages are asynchronous. This improves the accuracy and stability of the detection data.

[0012] Furthermore, the connector also includes a connecting block located at the bottom, the connecting block having a connecting structure, and the connecting block being detachably connected to the pull head through the connecting structure.

[0013] Using the above technical solution, the connecting block and the pulling head are detachably connected. In actual operation, the pulling head and the test piece can be pre-assembled, and after fixing and calibrating them, the assembled whole component can be installed onto the main body of the equipment through the connecting block. This step-by-step assembly method allows the connection process between the pulling head and the test piece to be unrestricted by the position of the main structure, and can be completed independently in a more open or suitable environment, improving the convenience and accuracy of operation, while also reducing the difficulty of performing complex alignment directly in a confined space.

[0014] Furthermore, the connection structure has a connection groove with a side opening on the connection block, and the top of the pull head is connected to an insert block. The insert block can be inserted into the connection groove through the side opening of the connection block and is prevented from detaching from the connection block.

[0015] By adopting the above technical solution, the connecting block and the pull head are detachably connected by inserting the plug into the connecting slot, which provides a fast and reliable connection method. During operation, simply align the plug with the connecting slot and push it in to achieve precise locking. When disassembly is required, simply pull out the plug in the opposite direction to separate the components. This makes the replacement and installation of the pull head very convenient and can be completed without tools, thus improving the efficiency of the testing work.

[0016] Furthermore, the connector also includes an upper connecting rod and a lower connecting rod located between the slider and the connecting block. The top end of the upper connecting rod is fixedly connected to the slider, the bottom end of the upper connecting rod is connected to the top end of the lower connecting rod around a rotation axis extending forward and backward, and the bottom end of the lower connecting rod is connected to the connecting block around a rotation axis extending left and right.

[0017] By adopting the above technical solution, this design enables the pull-out head to have universal adjustment capabilities, allowing it to swing freely and automatically center within a certain angle range after connection. In traditional straight-rod rigid connection methods, when there are machining and assembly deviations in the installation of the testing equipment or in the upper structure, the straight-rod connection will directly transmit all deviations to the specimen, resulting in uneven stress or positional misalignment of the specimen, thus affecting the accuracy of the test results. With the universal structure, the pull-out head can automatically adjust its posture according to the actual contact state, compensating for minor deviations in angle and position in real time. Regardless of the spatial position of the upper connecting block, the pull-out head can always adaptively find the optimal force direction coinciding with the specimen axis, ensuring that the applied tensile force is strictly transmitted along the specimen axis. This self-centering characteristic avoids the generation of lateral force components, protecting the specimen from damage by non-axial loads and ensuring the authenticity and repeatability of the test data.

[0018] Furthermore, the upper connecting rod includes a threaded rod and a threaded block. The threaded rod is fixedly connected to the bottom end of the slider, and the threaded block is screwed onto the bottom end of the threaded rod. The bottom end of the threaded block is hinged to the lower connecting rod.

[0019] Using the above technical solution, the upper connecting rod is a detachable split structure. The slider and threaded rod are first assembled onto the connecting seat, and then the threaded block is connected to the bottom end of the threaded rod, which facilitates the assembly of the entire connecting part and the connecting seat.

[0020] Furthermore, the pull-down mechanism includes a pull-down seat, on which multiple pull-down grooves are arranged horizontally at intervals. Each pull-down groove corresponds to a pull-down head. The pull-down grooves extend in the front-back direction and have an inverted T-shaped cross-section. At least one end of the pull-down groove in the horizontal direction passes through the pull-down seat. At the junction of the large-diameter section and the small-diameter section of the pull-down groove, there are two horizontally opposite stop steps.

[0021] The above technical solution employs a pull-out groove with an inverted T-shaped cross-section, at least one end of which extends to the side of the pull-out seat, forming an open interface. This design simplifies specimen installation. During operation, the specimen is simply pushed horizontally into the groove from the through end of the pull-out seat, allowing it to smoothly slide into the predetermined position of the inverted T-shaped groove. Once fully in place, the naturally formed retaining steps on both sides of the groove precisely press against the two edges of the top surface of the cement mortar block on the specimen base, thus limiting the specimen's position. The entire process requires no complex alignment adjustments or additional fasteners; the clamping action is completed in one smooth motion, improving the efficiency of specimen clamping and providing a reliable positioning basis for subsequent testing operations.

[0022] Furthermore, an annular baffle is provided below the stop step for padding the top surface of the cement mortar block of the base in the test block.

[0023] By employing the above technical solution, the pull-out force is more evenly distributed across the top surface of the specimen during application, avoiding excessive pressure caused by localized stress concentration. If only the side stops are in contact with the specimen, the edges of the specimen are highly susceptible to cracking or localized damage due to the inability to withstand the immense pressure as the pull-out force gradually increases. This would compromise the integrity of the specimen and prevent the acquisition of the true failure strength of the bond surface. The annular baffle increases the contact area with the top surface of the cement mortar base, resulting in a more even distribution of the pull-out force. This prevents the edges of the base block from cracking or being damaged due to excessive localized pressure, protecting the integrity of the specimen and ensuring the test can proceed smoothly until the bond surface fails.

[0024] Furthermore, the bottom of both stop steps is equipped with ball bearings that can move up and down elastically.

[0025] When using the above technical solution, minor manufacturing errors are unavoidable on the top surface of the cement mortar base blocks during batch preparation, such as insufficient flatness or inconsistent height. Without this design, when the top surface of a higher block first contacts the rigid stop step through the annular baffle, it will lead to excessive local stress in that area, while other areas have not yet made effective contact, resulting in uneven stress on the block during pull-out and even skewing. By setting elastically movable ball bearings, a dynamic adaptive contact is formed between the stop step and the top surface of the block. In the initial loading stage, each ball bearing can be independently fine-tuned according to the actual height of the corresponding block top surface, ensuring that the top surface of each block can achieve uniform and comprehensive contact with the stop step. This allows the pull-out force to be evenly applied to the entire block, avoiding stress concentration and uneven loading caused by manufacturing errors, and ensuring the authenticity and consistency of the test results.

[0026] Furthermore, each stop step is equipped with a row of horizontally spaced ball bearings.

[0027] By adopting the above technical solution, the ball bearings are distributed more densely and evenly, enabling more precise and comprehensive adaptive contact.

[0028] Furthermore, the pull-down seat has a ball track in the area above the stop step for the ball to slide up and down. The bottom end of the ball track has a ring of spherical groove to prevent the ball from falling off the bottom. Each ball has an air bladder above it that is opposite to the ball, and all air bladders are interconnected.

[0029] The above technical solution utilizes the principle of air pressure. When the test block is pulled down, the upper surface of the base block presses against the ball bearings, which slide upwards and compress the air bladders. Because the air bladders are interconnected, the internal air pressure remains balanced. This design, on the one hand, further absorbs the minor vibrations generated during the movement and breakage of the test block through the buffering effect of air pressure; on the other hand, the balanced air pressure ensures that the pushing force of each ball bearing on the test block is consistent, making the force on the test block more stable during movement, preventing skewing or jamming, and ensuring that the pull-out force is accurately along the vertical direction, resulting in more accurate test results.

[0030] The beneficial effects of the mortar tensile bond strength testing fixture provided by this invention are as follows: By sliding multiple sets of connectors on a connecting seat and keeping the vertical distance between the sliders on each connector and the corresponding limiting steps different, the sliders sequentially contact the corresponding limiting steps during the upward movement of the connecting seat, and the test blocks are sequentially pulled apart. This solves the problem of vibration interference when multiple test blocks are pulled out simultaneously, achieves the dispersion of the fracture sequence, and improves the accuracy of the test data. Simultaneously, by setting ball bearings at the stopping steps and placing airbags above the ball bearings, the downward pressure on the test blocks is more even, preventing uneven loading and stress concentration during the pull-out process. This ensures that the pull-out force is fully applied to separate the tested mortar layer and the base cement mortar block in a direction perpendicular to the bonding surface, further improving the accuracy of the test results. Attached Figure Description

[0031] Figure 1 A three-dimensional structural schematic diagram of a mortar tensile bond strength testing fixture provided by the present invention; Figure 2 A three-dimensional structural diagram of the connecting seat and pull-out seat in a mortar tensile bond strength testing fixture provided by the present invention. Figure 3 A front view of the connecting seat and pull-down seat in a mortar tensile bond strength testing fixture provided by the present invention; Figure 4 for Figure 3 Enlarged structural diagram at point A; Figure 5 A cross-sectional view of the connecting seat and pull-out seat in a mortar tensile bond strength testing fixture provided by the present invention; Figure 6 A side sectional view of the pull-out seat in a mortar tensile bond strength testing fixture provided by the present invention; Figure 7 for Figure 6 Enlarged structural diagram at point B; Figure 8 This is a three-dimensional structural diagram of the specimen tested by a mortar tensile bond strength testing fixture provided by the present invention.

[0032] Explanation of reference numerals in the attached figures: 1. Frame; 101. Portal frame; 102. Base; 2. Movable seat; 3. Connecting seat; 301. Sliding hole; 302. Limiting step; 4. Pull-down seat; 401. Pull-down groove; 402. Stopping step; 403. Annular spherical groove; 5. Threaded block; 6. Lower connecting rod; 7. Connecting block; 701. Connecting groove; 8. Insert block; 9. Pull-out head; 10. Airbag; 11. Ball bearing; 12. Connecting pipe; 13. Annular baffle; 14. Base cement mortar block; 15. Cement mortar layer under inspection; 16. Slider; 17. Threaded rod. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art should understand that the embodiments described below are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] The following is one embodiment of a mortar tensile bond strength testing fixture provided by the present invention: like Figures 1-8 As shown, a mortar tensile bond strength testing fixture includes a frame 1, a loading mechanism, a connecting seat 3, a connector, a pull-out head 9, and a pull-out mechanism.

[0035] like Figure 1 As shown, the frame 1 is arranged on a horizontal ground. The frame 1 includes a base 102 and a gate frame 101. The gate frame 101 is connected to the top of the base 102. A control console is provided on the side of the frame 1. The control console is equipped with a display screen for displaying the test results.

[0036] The loading structure is mounted on the portal frame 101. The loading structure includes a movable seat 2 that slides vertically within the portal frame 101. The movable seat 2 is driven by a servo motor in conjunction with a ball screw 11 to slide vertically on the portal frame 101. The movable seat 2 is the drive output end of the loading mechanism.

[0037] Connecting seat 3 is connected to the bottom of movable seat 2, such as... Figure 5 As shown, the connecting seat 3 is provided with a plurality of sliding holes 301 arranged at equal intervals in the left and right directions. The sliding holes 301 extend vertically and are variable diameter holes, including a large diameter hole section at the top and a small diameter hole section at the bottom. A limiting step 302 is formed between the large diameter hole section and the small diameter hole section. The height of each limiting step 302 decreases from left to right.

[0038] Multiple sets of connectors are provided, and the number of connectors is consistent with the number of sliding holes 301. Each connector is installed at each sliding hole 301.

[0039] The connecting components include a slider 16, an upper connecting rod, a lower connecting rod 6, and a connecting block 7 arranged sequentially from top to bottom.

[0040] The outer diameter of the slider 16 is consistent with the diameter of the large diameter section of the sliding hole 301. The slider 16 slides through the large diameter section of the sliding hole 301 in the up-down direction.

[0041] The upper connecting rod includes a threaded rod 17 and a threaded block 5 arranged sequentially from top to bottom. The top end of the threaded rod 17 is fixedly connected to the bottom of the slider 16. The threaded rod 17 slides through the small diameter section of the sliding hole 301 in the vertical direction. The threaded block 5 is provided with a threaded hole, and the threaded block 5 is screwed onto the bottom end of the threaded rod 17 through the threaded hole.

[0042] like Figure 2 , Figure 3 As shown, the top of the lower connecting rod 6 is hinged to the threaded block 5 around the rotation axis that extends back and forth.

[0043] The connecting block 7 is hinged to the bottom end of the lower connecting rod 6 around the rotation axis extending to the left and right. The connecting block 7 is provided with a connecting groove 701 with an inverted T-shaped cross section. The connecting groove 701 extends backward through the rear side wall of the connecting block 7, that is, the connecting groove 701 has a side opening on the rear side wall of the connecting block 7. The connecting groove 701 is the connecting structure on the connecting block 7.

[0044] Multiple pull-out heads 9 are provided, each having an adhesive bottom surface for bonding to the top surface of the tested mortar layer in the specimen. A T-shaped insert 8 is fixedly connected to the top of the pull-out head 9. The insert 8 is inserted from back to front into the connecting groove 701 on the connecting block 7, allowing the pull-out head 9 to be detachably connected to the connecting block 7. During testing, the connection between the pull-out head 9 and the specimen can be completed first, and then the pull-out head 9 with the specimen attached can be connected to the connecting block 7.

[0045] The pull-down mechanism includes a pull-down seat 4, which is fixedly installed on the base 102. The pull-down seat 4 is provided with a plurality of pull-down grooves 401 arranged at equal intervals in the left and right directions. The plurality of pull-down grooves 401 are respectively aligned with the plurality of sliding holes 301 on the connecting seat 3.

[0046] The pull-down groove 401 has an inverted T-shaped cross-section. The pull-down groove 401 extends along the front-to-back direction, and its rear end penetrates the pull-down seat 4. The specimen can be inserted into the pull-down groove 401 from back to front. Figure 4As shown, two opposing stop steps 402 are formed at the junction of the large-diameter section and the small-diameter section of the pull-out groove 401. The stop steps 402 are used to press on the top surface of the base cement mortar block 14 in the specimen to cooperate with the pull-out head 9 to realize the testing of the specimen.

[0047] like Figure 4 , Figure 8 As shown, a square-shaped annular baffle 13 is provided below the stop step 402. The annular baffle 13 is used to pad the stop step 402 and the part of the cement mortar block of the base in the specimen located on the outside of the tested mortar layer.

[0048] like Figure 6 , Figure 7 As shown, the pull-down seat 4 has mounting cavities in the solid area above the two stop steps 402. Each mounting cavity includes multiple airbag receiving cavities arranged at equal intervals along the front-to-back direction, connected by multiple front-to-back extending connecting cavities. Each airbag receiving cavity has a vertically extending ball bearing slide at its bottom. The bottom end of the ball bearing slide has an annular spherical groove 403. Each ball bearing slide contains a ball bearing 11. The inner diameter of the annular spherical groove 403 is smaller than the outer diameter of the ball bearing 11, thus supporting the ball bearing 11 and preventing it from falling off the bottom. Under its own weight, the bottom end of the ball bearing 11 can extend below the stop step 402.

[0049] Each of the aforementioned airbag accommodating cavities is equipped with an airbag 10, which is made of elastic material and is positioned above the corresponding ball bearing 11. Each connecting cavity is equipped with a connecting pipe 12, and multiple airbags 10 located at the same stop step 402 are interconnected through the connecting pipe 12.

[0050] The two mounting cavities are connected by a connecting pipe, so that the multiple airbags 10 at the two stop steps 402 are interconnected.

[0051] In use, the present invention first prepares multiple base cement mortar blocks 14, then places a molding frame on top of the base cement mortar blocks 14, injects the test mortar into the molding frame and compacts it, places the specimen in a natural environment to allow it to harden initially, and removes the molding frame after the test mortar has hardened initially. The resulting structure is the specimen.

[0052] The surface of the mortar layer to be inspected is ground, and then a layer of high-strength epoxy adhesive is applied to the bonding bottom surface of the pull-out head 9. The pull-out head 9 is aligned with the ground surface of the mortar layer to be inspected, and the pull-out head 9 is pressed and fixed onto the mortar layer to be inspected.

[0053] Then, the annular baffle 13 is placed on the outside of the mortar layer to be tested. The specimens bonded together and the specimens in the pull-out head 9 are aligned from back to front with the pull-out groove 401, so that the insert block 8 above the pull-out head 9 is aligned with the connecting groove 701 on the connecting block 7, thus completing the assembly of the specimens.

[0054] After all the test pieces are assembled, the loading mechanism is activated. The movable seat 2 drives the connecting seat 3 to move upward. During the upward movement of the connecting seat 3, since the heights of the limiting steps 302 at each sliding hole 301 in the connecting seat 3 are different, each limiting step 302 contacts the corresponding slider 16 in sequence from left to right. Therefore, each test piece on the pull-down seat 4 breaks in sequence from left to right. There is a clear time interval between the breaks of each two test pieces. During this time interval, the vibration generated by the previous broken test piece can dissipate, thereby avoiding the cumulative impact on the test results of the next test piece during the breakage process, making the test results of each test piece more accurate.

[0055] As the specimen begins to move upward within the pull-down groove 401, due to the microscopic height difference between the top surfaces of the various base cement mortar blocks 14, the highest point will be the first to contact the bottom of its corresponding ball bearing 11. This ball bearing 11 experiences an upward thrust, compressing the corresponding air bladder 10 on its back. As the specimen continues to move slightly upward, the air pressure within the compressed air bladder 10 rapidly increases. Since the air bladders 10 located on the same side of the stop step 402 are interconnected, and the air bladders 10 on the left and right sides are also interconnected, the air pressure generated by the compression at the higher point is instantly transmitted through the connecting pipe 12 to the air bladders 10 behind all other balls bearings 11 that have not yet made sufficient contact. As the specimen continues to move upward, the top surfaces of all base cement mortar blocks achieve close contact with their respective ball bearings 11.

[0056] According to Pascal's principle and the principle of minimum energy, since all air bladders 10 are interconnected and the internal air pressure is equal everywhere, the downward pressure exerted by each ball bearing 11 on the top surface of the base cement mortar block is completely consistent. The floating of the ball bearings 11 eliminates height errors, and the interconnection of the air bladders 10 achieves pressure equalization. This ensures that regardless of the height of the top surface of the base cement mortar block 14, the downward pull-out force acting on each specimen is ultimately vertical, uniform, and synchronous. This ensures that the specimen experiences an accurate downward tensile force, making the test results more accurate.

[0057] This invention, by setting multiple sliding holes 301, with each sliding hole 301 having a different height and position of the limiting step 302, allows each specimen to sequentially bear tensile force during a single pull-out process, achieving staggered loading. This reduces the impact of vibration generated by the first fractured specimen on the test results of subsequent fractured specimens, thus improving the reliability of the test results. Furthermore, by setting multiple ball bearings 11 and multiple interconnected airbags 10 pressing down on the ball bearings 11, the base cement mortar block 14 is subjected to uniform downward pressure, further enhancing the reliability of the test results.

[0058] In this embodiment, all connecting parts have the same length. When the connecting parts are not subjected to external force, all sliders 16 are at the same height. The limiting steps 302 are set to different heights, so that the vertical distance between the sliders 16 and the corresponding limiting steps 302 is different. In other embodiments, multiple limiting steps 302 can be set to the same height, and the connecting parts can be set to different lengths. When the connecting parts are not subjected to external force, the height position of each slider 16 is different, so that the vertical distance between each slider 16 and the corresponding limiting step 302 is different.

[0059] In this embodiment, the connecting structure on the connecting block 7 is a connecting groove 701 with an inverted T-shaped cross-section. The top of the pulling head 9 is connected to a T-shaped insert 8. The insert 8 is inserted into the connecting groove 701 to achieve a detachable connection between the connecting block 7 and the pulling head 9. In other embodiments, the connecting structure can be a vertically arranged connecting block 1 connected to the bottom of the connecting block 7. The connecting block 1 has a horizontally penetrating connecting hole 1. The top of the pulling head 9 is connected to a vertically arranged connecting plate 2. The connecting plate 2 has a horizontally penetrating connecting hole 2. The connecting plate 1 and the connecting plate 2 fit together. The connecting bolt passes through the connecting hole 1 and the connecting hole 2 to fix the connecting plate 1 and the connecting plate 2 together, thereby achieving a detachable connection between the pulling head 9 and the connecting block 7.

[0060] In this embodiment, the upper connecting rod includes a threaded rod 17 and a threaded block 5 threadedly connected to the bottom end of the threaded rod 17, which is a split structure. In other embodiments, the upper connecting rod is a single integral rod.

[0061] In this embodiment, a ball bearing 11 is provided at the stop step 402 at the pull-down seat 4. In other embodiments, the ball bearing 11 is not provided at the stop step 402. In this case, before performing the bonding strength test, it is necessary to grind the top surface of the base cement mortar block 14 to make the top surface of the base cement mortar block 14 smooth and flat, so as to avoid the stop step 402 generating a lateral component force on the specimen and affecting the test results. At this time, since the top surface of the base cement mortar block 14 needs to be ground, the preparation operation steps become more complicated and the overall testing efficiency is low.

[0062] In this embodiment, by setting airbags 10 above each ball bearing 11, the ball bearing 11 can slide up and down elastically, and all airbags 10 are connected. Thus, when facing an uneven base cement mortar block 14, each ball bearing 11 can apply the same pressure to each contact point on the base cement mortar block 14. In other embodiments, the ball bearing 11 is connected to the stop step 402 by springs that can extend and retract up and down. In this case, each ball bearing 11 floats independently by an independent spring and can extend and retract independently according to the actual height of the top surface of the corresponding base cement mortar block 14, realizing point-to-point height error compensation and ensuring that each contact point can fit. However, in this case, it is not possible to make each ball bearing 11 apply the same amount of pressure to the base cement mortar block 14 as in the scheme of setting airbags 10.

Claims

1. A mortar tensile bond strength testing fixture, comprising a frame (1), a loading mechanism provided on the frame (1), the loading mechanism having a drive output end capable of vertical movement, a pull-out head (9) for bonding the tested mortar layer on the test block connected to the drive output end of the loading mechanism, and a pull-down mechanism for pulling down the base cement mortar block on the test block, characterized in that, Also includes: Connecting seat (3) is connected to the drive output end of the loading mechanism; The connector is provided in multiple sets at horizontal intervals. The connector includes a slider (16). Each slider (16) slides vertically through the connector (3). The connector (3) is provided with a limiting step (302) below each slider (16) to limit the downward sliding stroke of the slider (16). When each connector is not subjected to external force, the vertical distance between the slider (16) and the corresponding limiting step (302) is different. The pull-down mechanism includes a pull-down seat (4), on which a plurality of pull-down grooves (401) are arranged horizontally at intervals. Each pull-down groove (401) corresponds to each pull-down head (9). The pull-down grooves (401) extend in the front-back direction and have an inverted T-shaped cross section. At least one end of the pull-down groove (401) in the horizontal direction passes through the pull-down seat (4). At the junction of the large-diameter section and the small-diameter section of the pull-down groove (401), there are two horizontally opposite stop steps (402). The bottom of both stop steps (402) is provided with ball bearings (11) that can move up and down elastically. Each stop step (402) is provided with a row of horizontally spaced ball bearings (11). The pull-down seat (4) is provided with a ball track in the area above the stop step (402) for the ball (11) to slide up and down. The bottom end of the ball track has a ring of spherical groove (403) to prevent the ball (11) from falling from the bottom. Each ball (11) is provided with an air bladder (10) above it, which is vertically opposite to the ball (11). All air bladders (10) are interconnected. The pull-down seat (4) has an installation cavity in the solid area above the two stop steps (402). The installation cavity includes multiple airbag receiving cavities arranged at equal intervals along the front and rear directions. The multiple airbag receiving cavities are connected to each other through multiple front and rear extending connecting cavities. The bottom of each airbag receiving cavity is connected to a vertically extending ball slide. The bottom end of the ball slide has a section of annular spherical groove (403). Each ball slide has a ball (11). The inner diameter of the annular spherical groove (403) is smaller than the outer diameter of the ball 11, thereby supporting the ball (11) and preventing the ball (11) from falling from the bottom. Under its own weight, the bottom end of the ball (11) can extend to below the stop step (402). The two mounting cavities are connected by a connecting pipe, so that the multiple airbags (10) at the two stop steps (402) are interconnected.

2. The mortar tensile bond strength testing fixture according to claim 1, characterized in that, The connector also includes a connecting block (7) located at the bottom, the connecting block (7) is provided with a connecting structure, and the connecting block (7) is detachably connected to the pull head (9) through the connecting structure.

3. The mortar tensile bond strength testing fixture according to claim 2, characterized in that, The connection structure is a connection groove (701) with a side opening on the connection block (7). The top of the pull head (9) is connected to a plug (8). The plug (8) can be inserted into the connection groove (701) through the side opening of the connection block (7) and is anti-detached from the connection block (7).

4. The mortar tensile bond strength testing fixture according to claim 3, characterized in that, The connector also includes an upper connecting rod and a lower connecting rod (6) located between the slider (16) and the connecting block (7). The top end of the upper connecting rod is fixedly connected to the slider (16), the bottom end of the upper connecting rod is connected to the top end of the lower connecting rod (6) around the rotation axis extending forward and backward, and the bottom end of the lower connecting rod (6) is connected to the connecting block (7) around the rotation axis extending left and right.

5. The mortar tensile bond strength testing fixture according to claim 4, characterized in that, The upper connecting rod includes a threaded rod (17) and a threaded block (5). The threaded rod (17) is fixedly connected to the bottom end of the slider (16), and the threaded block (5) is threaded onto the bottom end of the threaded rod (17). The bottom end of the threaded block (5) is hinged to the lower connecting rod (6).

6. The mortar tensile bond strength testing fixture according to claim 1, characterized in that, Below the stop step (402) is an annular baffle (13) for padding the top surface of the stop step (402) and the base cement mortar block (14) in the test block.

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