Improved pull-out test device based on electronic universal testing machine

Abstract

The utility model discloses an improved pull-out test device based on an electronic universal testing machine, which comprises a pull-out device and a pull-out clamp which are arranged on the electronic universal testing machine, and a movable cross beam is arranged on the electronic universal testing machine; the upper end of the drawing clamp is fixed on the movable cross beam through a transverse bolt, the lower end of the drawing clamp is provided with a groove for mounting a drawing spindle, and the drawing spindle is positioned above the paving material; a groove is formed in the lower end of the drawing clamp and is used for fixing a drawing spindle; the drawing device comprises a drawing frame for placing a paving material, and the drawing frame is mounted in the electronic universal testing machine through a bulge fixing device; the drawing frame comprises an upper panel and a lower panel, an adjustable bolt is arranged between the upper panel and the lower panel, and the height of the upper panel and the height of the lower panel are adjusted through the adjustable bolt; and paving materials are placed on the lower panel.

Description

Technical Field

[0001] The utility model relates to testing equipment, in particular to a pulling test device improved based on an electronic universal testing machine. Background Art

[0002] The paving of long-span steel bridge decks is a difficult problem in pavement engineering. After years of development, my country's steel bridge deck asphalt paving has gradually formed four major paving material systems: mastic asphalt macadamia mixture (SMA), cast asphalt concrete (GA), epoxy asphalt concrete (EA), and modified dense graded asphalt concrete (AC). The paving structure has also developed from the past "single-layer homogeneous" to "double-layer homogeneous" and "double-layer heterogeneous" structures. For this double-layer heterogeneous paving structure, the bonding performance of the bonding layer and the upper and lower layers is crucial. Good interlayer bonding performance can ensure that the paving composite structure becomes a force-bearing whole, so that the load is effectively transferred between the paving structures. By coordinating the deformation between the paving structure layers, the structural advantages of the double-layer paving structure can be fully utilized. At present, the bonding strength between the paving structure layers is mainly studied at home and abroad through shear tests and pull-out tests.

[0003] The Technical Specifications for Design and Construction of Highway Steel Bridge Deck Pavement (JTC / T3364-02-2019) mentions the use of universal material testing machines for pull-out tests. However, there are many types of universal material testing machines on the market, and the specification does not specify which type of testing machine. Usually, they are equipped with fixed fixtures for pull-out tests, which mainly involves connecting the test specimen to the upper and lower fixtures, which makes the operation complicated and difficult.

[0004] Under the combined effects of vehicle loads and climate, the steel bridge deck pavement is subject to significant tensile stress, shear stress, compressive stress and other complex loads, resulting in cracking, delamination and other defects. The strength of asphalt mixture in tension, bending, shear and compression is based on adhesion. At present, the PosiTestAT-A fully automatic puller is commonly used in laboratories to measure adhesion. The working principle of the PosiTestAT-A fully automatic puller is to use hydraulic pressure to separate a certain diameter of the coating from the surface of the substrate to measure the adhesion of the coating.

[0005] The pull-out test is usually used to evaluate the interlayer bond strength of the pavement structure. In the laboratory, a double-sided saw is usually used to cut the composite structure, followed by core drilling. The core drilling depth is approximately the middle of the lower layer. After the core drilling is completed, the surface of the specimen is polished to a flat surface, and the pull-out spindle is bonded to the surface of the specimen with AB glue.

[0006] The pullers commonly used in laboratories at present include the PosiTest AT-A fully automatic puller mentioned above.

[0007] PosiTestAT-A fully automatic puller has problems:

[0008] (1) When measuring the pull-out properties of asphalt mixture specimens in the laboratory, the process is unstable and data is usually recorded manually, which is troublesome. The electronic universal testing machine is connected to a computer to facilitate data and graphic analysis.

[0009] (2) Usually measures the adhesion of coatings (such as asphalt, epoxy resin, etc.).

[0010] (3) The selection gradient of drawing rate and drawing ingot size is small. Currently, there are only two sizes: 20 mm and 50 mm, which is not conducive to detailed analysis.

[0011] (4) During the test, not only the drawing spindle is stained with the coating, but also the contact surface of the reaction device is stained with the coating, which affects the test accuracy.

[0012] In the prior art, the bonding strength test results of the waterproof bonding layer of concrete bridge deck pavement using an electronic puller, a tensile testing machine and an asphalt mixture testing machine for acrylic resin, water-based epoxy asphalt and high-viscosity emulsified asphalt respectively show that for flexible asphalt materials, the electronic puller cannot provide a larger measurement stroke, and the secondary bonding effect of the residual asphalt material will lead to large differences in the test results (Research on the on-site detection technology of the waterproof bonding layer of concrete bridge deck pavement). The tensile testing machine is used for the pull-out test, and the upper and lower joints of the upper end of the testing machine are used to fix the fixture for the test. It is of reference value for smaller specimens, but it is difficult to fix and provide strong reaction force support for the larger asphalt mixture rutting plate specimens commonly made in the laboratory.

[0013] In the existing technology, in order to study the properties of asphalt-aggregate interface under the influence of salt immersion and freeze-thaw cycles, the influence of three factors, namely, salt mass fraction, immersion time, and freeze-thaw cycles, on the tensile strength and tensile strength loss rate of aggregate-asphalt interface are considered according to the environment of the pavement. Granite bonding specimens with asphalt-aggregate interface are prepared indoors, and a universal testing machine is used to conduct a pull-out test (Study on the bonding performance of asphalt-aggregate interface under salt immersion and freeze-thaw cycles). In this test, two spherical hinge connections are set to ensure coaxial tension during loading. It is suitable for small-sized specimens and is mostly suitable for studying the bonding performance between layers. It is not suitable for large-sized rutting plate specimens. Utility Model Content

[0014] In view of the above-mentioned deficiencies, the utility model proposes a pulling test device based on an improved electronic universal testing machine, which can carry out pulling tests on asphalt mixtures in a more targeted manner. The electronic universal testing machine can freely adjust the pulling rate parameters and carry out pulling tests on pulling spindles of different sizes, so as to scientifically and rationally study the influence of the pulling rate and the pulling spindles, which is conducive to establishing a parameter range and providing scientific reference significance for engineering practice.

[0015] The utility model is implemented by at least one of the following technical solutions.

[0016] A pulling test device improved on an electronic universal testing machine comprises a pulling device and a pulling fixture installed on the electronic universal testing machine, wherein a movable crossbeam is provided on the electronic universal testing machine; the upper end of the pulling fixture is fixed to the movable crossbeam by a cross bolt, and a groove for installing a pulling spindle is provided at the lower end of the pulling fixture, and the pulling spindle is located above an asphalt mixture specimen.

[0017] Furthermore, a groove is provided at the lower end of the drawing fixture, and the groove is used to fix the drawing spindle.

[0018] Furthermore, the pulling device comprises a pulling frame for placing the asphalt mixture specimen, and the pulling frame is installed in the electronic universal testing machine through a protruding fixing device.

[0019] Furthermore, the pulling frame comprises an upper panel and a lower panel, and an adjustable bolt is provided between the upper panel and the lower panel, and the height of the upper panel and the lower panel is adjusted by the adjustable bolt; the asphalt mixture specimen is placed on the lower panel.

[0020] Furthermore, a movable bolt is provided between the upper panel and the lower panel. The movable bolt passes through the upper panel and mainly functions to fix the asphalt mixture specimen. The asphalt mixture specimen can be moved on the lower panel.

[0021] Furthermore, the upper panel is provided with a first circular hole and a second circular hole; the second circular hole is used for studying and analyzing the drawing spindle and for facilitating the smooth passage of the drawing fixture on the moving beam.

[0022] Furthermore, a sleeve is provided on the lower surface of the lower panel, and the entire drawing frame is installed on the raised fixing device through the sleeve.

[0023] Furthermore, the sleeve is provided with a circular hole, and the entire drawing frame is fixed on the universal testing machine through a transverse bolt and a protruding fixing device.

[0024] Furthermore, the protrusion fixing device is a pad with a protrusion, a round hole is provided in the protrusion, a sleeve is sleeved in the protrusion, and the pulling frame is fixed in the electronic universal testing machine by a transverse bolt.

[0025] Compared with the prior art, the utility model has the following beneficial effects:

[0026] The utility model proposes a pull-out test device and method based on an improved electronic universal testing machine, which solves the problems of stability and standardized control of current indoor pull-out tests. By using the electronic universal testing machine to perform pull-out tests, the rate gradient can be strictly subdivided, and the designed pull-out test frame can provide a larger reaction force, so as to achieve more accurate and reasonable control of the asphalt mixture pull-out test, facilitate and clearly obtain test data, and is conducive to studying the influence of factors such as the pull-out rate and the pull-out spindle size on the pull-out test, which is conducive to providing reference significance for actual engineering pull-out tests. The on-site pull-out detection method lacks standards and procedures. By establishing an indoor pull-out test evaluation system, on-site pull-out test detection is served. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation of the utility model or the technical solution in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation or the description of the prior art.

[0028] Figure 1 It is a structural schematic diagram of a pull-out test device improved based on an electronic universal testing machine in an embodiment;

[0029] Figure 2 It is a schematic diagram of the structure of the drawing device in the embodiment;

[0030] Figure 3 It is a top view of the structure of the drawing device in the embodiment;

[0031] Figure 4 It is a schematic diagram of the structure of the drawing fixture in the embodiment;

[0032] Figure 5 It is a front view of the structure of the drawing device in the embodiment;

[0033] In the figure: 1. electronic universal testing machine; 2. moving crossbeam; 3. pulling fixture; 4. upper panel; 5. first circular hole; 6. moving bolt; 7. pulling spindle; 8. raised fixing device; 9. sleeve; 10. lower panel; 11. asphalt mixture specimen; 12. adjustable bolt; 13. second circular hole. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical method and advantages of the utility model clearer, the utility model will be further described in detail below with reference to the accompanying drawings and specific examples. These examples are only illustrative and not limiting of the utility model.

[0035] like Figure 1 As shown, a pull-out test device based on an improved electronic universal testing machine of this embodiment comprises: a pull-out device and a pull-out fixture 3 installed on an electronic universal testing machine 1, wherein a moving crossbeam 2 is provided on the electronic universal testing machine 1; Figure 4As shown, the upper end of the drawing fixture 3 is fixed to the moving crossbeam 2 by a cross bolt, and a groove is provided at the lower end of the drawing fixture 3, and the groove is used to fix the drawing spindle 7 above the asphalt mixture specimen. The drawing fixture is designed with a groove according to the inherent drawing head size, and drawing spindles of different sizes are prepared for experimental research.

[0036] By moving the moving beam 2 at a uniform speed (it can move uniformly upward and downward) to control the stable application of the pulling force, it is beneficial to scientifically control the pull-out test. Installing the pull-out device on the electronic universal testing machine 1 is beneficial to use the advantages of the electronic universal testing machine such as stable operation and convenient data curve acquisition to perform the pull-out test of the asphalt mixture.

[0037] The pulling device includes a pulling frame and a protruding fixing device 8; the protruding fixing device 8 is located at the lower end of the electronic universal testing machine 1 and is used to fix the pulling frame; the pulling frame includes an upper panel 4, a lower panel 10, and a movable bolt 6; the movable bolt 6 passes through the upper panel 4 and is mainly used to fix the asphalt mixture specimen 11. The asphalt mixture specimen 11 can move on the lower panel 10, so that the pulling spindle 7 is fixed to the pulling fixture 3. An adjustable bolt 12 is provided between the upper panel 4 and the lower panel 10, and the height of the upper and lower panels (4, 10) can be adjusted by the adjustable bolt 12, which is conducive to the convenient operation of the test.

[0038] The upper panel 4 is provided with a first circular hole 5 and a second circular hole 13;

[0039] As an embodiment, the upper panel 4 is a steel plate with dimensions of 500 mm in length, 400 mm in width, and 30 mm in thickness. The first circular hole 5 drilled on the upper panel 4 has a radius of 50 mm, and the second circular hole 13 has a radius of 80 mm. In order to reduce the weight of the frame for easy testing, the design of the second circular hole 13 facilitates subsequent research and analysis of large-size drawing ingots and facilitates the smooth passage of the drawing fixture on the moving beam, which is convenient for observation and operation. The first circular hole 5 is mainly used to reduce the weight of the overall structure. Because the upper panel (steel plate) is large in size, by symmetrically designing four circular holes 5 on the upper panel, on the one hand, the weight is reduced, and on the other hand, the aesthetics is improved, the weight of the drawing frame is reduced, it is easy to carry, and the overall structure is simple.

[0040] The lower panel 10 is a steel plate with specific dimensions of 500 mm in length, 400 mm in width and 10 mm in thickness, and its main function is to provide a support platform for the mixed material specimen. Four movable bolts 6 pass through the upper panel 4 .

[0041] The upper and lower panels (4, 10) are supported by four adjustable bolts 12. The lower surface of the lower panel 10 is provided with a sleeve 9, which is fixed to the lower panel 10 of the drawing frame by welding. The sleeve 9 is provided with 4 round holes. The entire drawing frame is fixed to the universal testing machine 1 by a cross bolt and a protruding fixing device 8. The drawing frame of the utility model utilizes the lower end protruding device of the electronic universal testing machine and designs a sleeve structure, which is simple and convenient to fix the drawing frame. The upper and lower panels of the drawing frame are adjusted in height by adjustable bolts, which is beneficial to the test operation, and the upper panel has symmetrical openings, which reduces the weight on the one hand and is beautiful and simple on the other hand.

[0042] As an embodiment, the protrusion fixing device 8 is a pad with a protrusion, and four circular holes are provided in the protrusion, which correspond to the four circular holes on the four sides of the sleeve 9. The sleeve 9 is sleeved in the protrusion, and the pulling frame can be fixed by a cross bolt (latch pin).

[0043] In the field of road engineering, pull-out tests are usually divided into pull-out tests of coatings (asphalt, epoxy resin, etc.) and pull-out tests of cored mixtures. The pull-out test of coatings is to study the adhesion properties of coatings, which is usually carried out by directly applying them on stone slabs or steel plates; the other is the pull-out test of asphalt mixtures, which studies the bonding properties between layers, which is usually carried out through cored drilling. In the actual paving process of the project, there will also be on-site pull-out tests to determine whether the pavement is in good condition.

[0044] The test method of the improved pull-out test device based on the electronic universal testing machine comprises the following steps:

[0045] (1) Fix the pulling frame to the electronic universal testing machine 1 through four horizontal bolts at the front, back, left and right sides;

[0046] (2) Place the mixture specimen with the drawing spindle 7 attached on the lower panel 10, find a suitable position (where the drawing head and the drawing fixture 3 are fixed), and fix the asphalt mixture specimen with four movable bolts 6;

[0047] (3) Turn on the power, computer and universal testing machine;

[0048] (4) Slowly move the crossbeam 2 downward, move the drawing fixture 3 to the top of the mixed material specimen through the circular hole of the upper panel 4, and fix the drawing spindle;

[0049] (5) Input the pulling rate on the computer and start moving beam 2 to perform the pulling test;

[0050] (6) After the drawing test is completed, save the drawing data and drawing curve, and analyze the results.

[0051] The utility model designs a pull-out test device based on an electronic universal testing machine, utilizes the advantages of the electronic universal testing machine such as stability, scientificity, and convenience to conduct pull-out tests in the laboratory, and improves the scientificity of the pull-out test of asphalt mixtures. The goal is to propose reasonable pull-out parameters (pulling rate and pulling spindle size) through systematic research, establish a pull-out test evaluation system, conduct pull-out test evaluation and pull-out interface evaluation on actual paving projects, and help to conduct scientific and reasonable performance evaluation of in-service paving structures, so as to formulate accurate paving or repair and maintenance plans.

[0052] Stability: The electronic universal testing machine controls the moving crossbeam to pull upwards, with a stable moving speed and uniform force, and the 30mm thick upper panel provides a strong reaction force, which is sufficient for pulling the mixture. It is not only suitable for coating adhesion performance testing.

[0053] Scientificity: One end of the electronic universal testing machine is connected to a computer device, which can freely control the movement rate of the beam and thus control the pulling rate. The pulling rate parameter gradient is sufficiently refined. By setting pulling rates of different gradients, the pulling performance test of asphalt mixture can be carried out.

[0054] Convenience: One end of the electronic universal testing machine is connected to a computer device. During the pull-out test, the computer terminal draws a curve graph and displays parameters such as tension in real time, which is conducive to direct observation by the tester and convenient for research, analysis and storage after the test.

[0055] The preferred embodiments of the utility model disclosed above are only used to help explain the utility model. The preferred embodiments do not describe all the details in detail, nor do they limit the utility model to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the utility model, so that those skilled in the art can well understand and use the utility model.

Claims

1. A pull-out test device improved based on an electronic universal testing machine, characterized in that: The invention comprises a pulling device and a pulling fixture (3) installed on an electronic universal testing machine (1), wherein the electronic universal testing machine (1) is provided with a movable crossbeam (2); the upper end of the pulling fixture (3) is fixed to the movable crossbeam (2) by a cross bolt, and the lower end of the pulling fixture (3) is provided with a groove for installing a pulling spindle (7), wherein the pulling spindle (7) is located above the asphalt mixture test piece.

2. The pull-out test device improved based on the electronic universal testing machine according to claim 1 is characterized in that: The lower end of the drawing clamp (3) is provided with a groove, and the groove is used to fix the drawing spindle (7).

3. The pull-out test device improved based on the electronic universal testing machine according to claim 1 is characterized in that: The pulling device comprises a pulling frame for placing an asphalt mixture test piece, and the pulling frame is installed in the electronic universal testing machine (1) via a protruding fixing device (8).

4. The pull-out test device improved based on the electronic universal testing machine according to claim 3 is characterized in that: The pulling frame comprises an upper panel (4) and a lower panel (10); an adjustable bolt (12) is provided between the upper panel (4) and the lower panel (10); the heights of the upper and lower panels (4, 10) are adjusted by the adjustable bolt (12); and an asphalt mixture specimen is placed on the lower panel (10).

5. The pull-out test device improved based on the electronic universal testing machine according to claim 4 is characterized in that: A movable bolt (6) is provided between the upper panel (4) and the lower panel (10). The movable bolt (6) passes through the upper panel (4) and mainly functions to fix the asphalt mixture specimen. The asphalt mixture specimen can be moved on the lower panel (10).

6. The pull-out test device improved based on the electronic universal testing machine according to claim 5, characterized in that: The upper panel (4) is provided with a first circular hole (5) and a second circular hole (13); the second circular hole (13) is used for studying and analyzing the drawing spindle (7) and for facilitating the smooth passage of the drawing fixture (3) on the movable crossbeam (2).

7. The pull-out test device improved based on the electronic universal testing machine according to claim 3 is characterized in that: A sleeve (9) is provided on the lower surface of the lower panel (10), and the entire drawing frame is mounted on the raised fixing device (8) via the sleeve (9).

8. The pull-out test device improved based on the electronic universal testing machine according to claim 7 is characterized in that: The sleeve (9) is provided with a circular hole, and the entire drawing frame is fixed on the universal testing machine (1) through a transverse bolt and a protruding fixing device (8).

9. The pull-out test device improved based on the electronic universal testing machine according to claim 8, characterized in that: The protrusion fixing device (8) is a pad with a protrusion, a round hole is provided in the protrusion, a sleeve (9) is sleeved in the protrusion, and the pulling frame is fixed in the electronic universal testing machine (1) by a transverse bolt.

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