A beam specimen forming device and forming method for asphalt mixture

Abstract

The invention discloses a beam specimen molding device and a molding method for an asphalt mixture, and belongs to the technical field of asphalt mixtures for road engineering. The invention enables the molding device to mold beam specimens of different heights and different widths through structural design without cutting, thereby solving the problems of stress concentration caused by cutting rutting plates, failure to fully simulate vibration rolling in road construction, and difficulty in molding thick specimens in the molding and manufacturing process of small beam specimens of asphalt mixtures in existing experiments, thereby improving the accuracy of low-temperature cracking performance evaluation and fatigue performance verification tests of asphalt mixtures. At the same time, the invention is easy to operate and improves the accuracy and repeatability of test results.

Description

Technical Field

[0001] The invention belongs to the technical field of asphalt mixtures for road engineering, and in particular relates to a beam specimen forming device and a forming method for asphalt mixtures. Background Art

[0002] Asphalt pavement has the advantages of good driving comfort, short construction period and convenient maintenance, and has become the main pavement structure type of my country's high-grade highways. However, during the use of asphalt pavement, low-temperature cracking and fatigue damage are the main factors affecting its durability. Therefore, it is very important to evaluate the low-temperature and fatigue performance of asphalt mixtures.

[0003] In the process of evaluating the low-temperature cracking performance and verifying the fatigue performance of asphalt mixtures, a wheel roller is often used to form asphalt mixture rutting plates, and then the rutting plates are cut into small beams for testing. This test method has the following shortcomings: 1) This forming method cannot completely simulate the vibration rolling of pavement construction; 2) After the mixture is cut, the morphology of the end aggregate is destroyed, which is also easy to cause stress concentration and fails to truly reflect the structural state of the mixture; 3) For different types of mixtures, their thickness in the pavement structure also changes accordingly. The thickness of the middle and lower layers of asphalt pavements is generally 6-8cm, and the thickness of conventional rutting plates is generally 5cm. It is difficult to form AC-20 or AC-25 mixtures. When the thickness of the rutting plate increases to 10cm, it is difficult for the wheel roller to compact the mixture. Therefore, the development of a new type of asphalt mixture small beam forming device is of great significance to improve the reliability of low-temperature cracking and fatigue tests of asphalt mixtures. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a beam specimen molding device and a molding method for asphalt mixture. The molding device of the present invention can mold beam specimens of different heights (thicknesses) and widths without cutting, which solves the problems of stress concentration caused by cutting rutting plates in the molding and production process of small beam specimens of asphalt mixture in existing experiments, the inability to fully simulate the vibration rolling of road construction, and the difficulty in molding thick specimens, thereby improving the accuracy of low-temperature cracking performance evaluation and fatigue performance verification tests of asphalt mixtures; at the same time, it is easy to operate and improves the accuracy and repeatability of test results.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions to solve it.

[0006] (1) A beam specimen molding device for asphalt mixture, comprising: a test stand, on which a lifting unit, a mold and a vibration unit are arranged from bottom to top; wherein the bottom of the lifting unit is fixed to the test stand, and a support plate is horizontally arranged on the upper end of the lifting unit, and the support plate has a certain thickness; the support plate has multiple groups of wheel grooves on the left and right sides of the upper surface, respectively, and rolling wheels are arranged in the roller grooves, and the upper surface of the support plate has multiple shaft grooves corresponding to each group of wheel grooves, and a fixed shaft is installed in each shaft groove, and the rolling wheel is sleeved on the fixed shaft; the lower surface of the support plate has a semicircular rotating shaft; the upper end of the lifting unit has a bracket matching the semicircular rotating shaft, and the semicircular rotating shaft rotates in the bracket;

[0007] The mold is a rectangular hollow shell with openings at the upper and lower ends, a mold cover is provided at the upper end of the mold, and a heating component is arranged in the hollow cavity of the shell; the lower ends of the left and right walls of the mold respectively have bending parts, and a movable baffle is mounted on the bending parts, and the movable baffle and the side wall of the mold form a loading cavity, and the asphalt mixture is loaded into the loading cavity;

[0008] The width of the support plate is smaller than the spacing between each set of bending parts, and when the lifting unit moves upward, the support plate moves upward to make the rolling wheel move upward against the movable baffle;

[0009] The upper end of the vibration unit is fixed on the test bracket, and the lower end of the vibration unit is installed with a mold cover.

[0010] Furthermore, a plurality of groups of vertical grooves are respectively provided on the left and right walls of the mold, a partition is arranged in each group of the vertical grooves, the lower end of each group of the partitions has an inward bending portion, a corresponding movable baffle is mounted on the bending portion, and each group of the partitions and the corresponding movable baffle form a loading cavity with an open upper end, and the asphalt mixture is loaded into the loading cavity.

[0011] Furthermore, one movable baffle and two partitions form a set of material components, and the forming device is equipped with multiple sets of material components.

[0012] Furthermore, the lifting unit is a screw lift, the upper end of the lifting rod of the screw lift is provided with a bracket, and a semicircular rotating shaft is installed in the bracket.

[0013] Furthermore, there is a gap between the upper end of the bracket and the lower surface of the support plate.

[0014] Furthermore, a roller is provided on the outer side wall of the mold, and a guide rail is provided at a corresponding position of the test bracket, and the roller moves along the guide rail to move the mold left and right.

[0015] Furthermore, the vibration unit includes a vibration motor and a reaction frame, and a mold cover is installed on the reaction plate of the reaction frame.

[0016] Furthermore, the heating component is a heating resistance wire.

[0017] Furthermore, a displacement sensor is installed at the lifting position of the lifting unit.

[0018] (ii) A method for forming a beam specimen of an asphalt mixture, comprising the following steps:

[0019] Step 1: according to the width of the beam specimen required for the test, a partition is installed in the corresponding vertical groove, and a corresponding movable baffle is mounted on the partition to form a corresponding loading cavity; and the asphalt mixture to be formed is added into the loading cavity;

[0020] Step 2, turning on the heating component to heat the material to the temperature required for the test; turning on the vibration unit to vibrate and compact the asphalt mixture to be formed in the mold to form a uniform material to be compacted;

[0021] Step 3, turn on the lifting unit to make the bracket move upward with the support plate. When the rolling wheel presses against the movable baffle, under the action of vibration, the rolling wheel and the support plate begin to rotate back and forth to press the movable baffle. When the material on the movable baffle presses against the mold cover, the beam specimen is obtained after continuous pressing for a predetermined time.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention makes the height of the asphalt mixture beam specimen adjustable by designing a movable baffle, a lifting unit and a vibration unit. Even for a specimen with a large thickness, a dense and uniform specimen can be formed. At the same time, the stress concentration caused by the traditional cutting rutting plate is avoided, so that the beam specimen obtained by the present invention can more accurately test and verify the low-temperature cracking performance and fatigue performance of the asphalt mixture.

[0024] (2) The present invention can more realistically simulate the vibration rolling process of road construction through the structural design of the rolling wheel and the support plate.

[0025] (3) The present invention can form beam specimens of different widths by setting up multiple groups of vertical grooves, partitions and movable baffles. Therefore, the produced specimens do not need to be cut, which solves the problem of stress concentration caused by cutting rutting plates during the forming and production process of asphalt mixture small beam specimens in existing experiments, and at the same time improves the forming efficiency.

[0026] (4) The method of the present invention has a simple operation process and high repeatability, which improves the accuracy of the test results of various properties of asphalt mixtures by the formed beam specimens. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Figure 1 It is a schematic diagram of the three-dimensional structure of a beam specimen forming device for asphalt mixture according to an embodiment of the present invention;

[0029] Figure 2 for Figure 1 The main view of

[0030] Figure 3 for Figure 2 AA section view;

[0031] Figure 4 for Figure 1 Right view of;

[0032] Figure 5 for Figure 4 BB cross-sectional view;

[0033] Figure 6 A schematic diagram of a three-dimensional structure of a mold according to an embodiment of the present invention;

[0034] Figure 7 A schematic diagram of a three-dimensional structure of a support plate according to an embodiment of the present invention;

[0035] In the above figure, 1 test bracket; 2 lifting unit; 201 bracket; 3 mold; 301 heating component; 302 bending part; 303 vertical groove; 304 roller; 305 guide rail; 4 vibration unit; 401 vibration motor; 402 reaction frame; 5 support plate; 501 rolling wheel; 502 fixed shaft; 503 semicircular rotating shaft; 6 mold cover; 7 movable baffle. DETAILED DESCRIPTION

[0036] The embodiments and effects of the present invention are further described in detail below with reference to the accompanying drawings.

[0037] Example 1

[0038] refer to Figure 1-7, a beam specimen molding device of asphalt mixture of the present invention comprises: a test support 1, on which a lifting unit 2, a mold 3 and a vibration unit 4 are arranged from bottom to top; wherein, the bottom of the lifting unit 2 is fixed on the test support 1, and a support plate 5 is horizontally arranged on the upper end of the lifting unit 2, and the support plate 5 has a certain thickness; the support plate 5 has multiple groups of wheel grooves on the left and right sides of the upper surface, and a rolling wheel 501 is arranged in the groove of the roller 304, and the upper surface of the support plate 5 has multiple shaft grooves corresponding to each group of wheel grooves, and a fixed shaft 502 is installed in each of the shaft grooves, and the rolling wheel 501 is sleeved on the fixed shaft 502; the lower surface of the support plate 5 has a semicircular rotating shaft 503; the upper end of the lifting unit 2 has a bracket 201 matching the semicircular rotating shaft 503, and the semicircular rotating shaft 503 rotates in the bracket 201;

[0039] The mold 3 is a rectangular hollow shell with openings at the upper and lower ends respectively, a mold cover 6 is provided at the upper end of the mold 3, and a heating component 301 is arranged in the hollow cavity of the shell; the lower ends of the left and right walls of the mold 3 respectively have bending portions 302, and a movable baffle 7 is mounted on the bending portion 302, and the movable baffle 7 and the side wall of the mold 3 form a loading cavity, and the loading cavity is filled with asphalt mixture; the width of the support plate 5 is smaller than the spacing between each group of bending portions 302, and when the lifting unit 2 moves upward, the support plate 5 moves upward so that the rolling wheel 501 moves upward against the movable baffle 7; the upper end of the vibration unit 4 is fixed on the test bracket 1, and the mold cover 6 is installed at the lower end of the vibration unit 4.

[0040] In the above embodiments, the test bracket 1 is used to fix and install various components while ensuring the stability of the device; when loading, the movable baffle 7 is installed from the upper opening end of the mold 3, so that the movable baffle 7 is stuck in its bent portion 302, and the asphalt mixture to be formed is loaded from the upper end opening of the mold 3 into the loading cavity formed by the mold 3 and the movable baffle 7. Here, the mass of the asphalt mixture to be loaded is calculated according to the size of the beam specimen to be formed. The lifting unit 2 drives the support plate 5 to move upward, so that the rolling wheel 501 on the support plate 5 is against the movable baffle 7. With the vibration of the vibration unit 4, the entire device begins to vibrate, so that the rolling wheel 501 rotates at a small angle relative to the movable baffle to roll the movable baffle 7. As the lifting part of the lifting unit 2 rises further, the support plate 5 pushes the movable baffle 7 into the mold 3 until the asphalt mixture in the mold 3 contacts the inner wall of the mold cover 6 that matches the top of the mold 3. In this way, the material in the closed space formed by the mold cover 6, the mold 3 and the movable baffle 7 is pushed upward by the lifting unit 2 while vibrating, and the rolling wheel 501 also rolls the movable baffle 7. In this rising process, the support plate 5 and the movable baffle 7 move synchronously, and the support plate 5 swings back and forth along the semicircular rotating shaft 503, so that the support plate 5, the rolling wheel 501 and the movable baffle 7 form a follow-up movement in the front and rear directions, so that the rolling effect of the present invention is more uniform, and the vibration rolling process of road construction can be more realistically simulated. After the specimen is formed, the vibration unit 4 is turned off, and the lifting part of the lifting unit 2 is lowered to take out the specimen.

[0041] The specimen forming process of the present invention can make the height of the asphalt mixture beam specimen adjustable, and the setting of the vibration unit 4 can form a dense and uniform specimen even for a specimen with a large thickness. At the same time, the stress concentration caused by the traditional cutting of the rutting plate is avoided, so that the beam specimen obtained by the present invention can more accurately test and verify the low-temperature cracking performance and fatigue performance of the asphalt mixture.

[0042] refer to Figure 1 and 6 According to one embodiment of the present invention, a plurality of groups of vertical grooves 303 are respectively provided on the left and right walls of the mold 3, a partition is arranged in each group of the vertical grooves 303, and each group of the partitions has an inward bending portion 302 at the lower end, and a corresponding movable baffle 7 is mounted on the bending portion 302, and each group of the partitions and the corresponding movable baffle 7 form a loading cavity with an upper opening, and the loading cavity is loaded with asphalt mixture.

[0043] refer to Figure 1 and 6 According to one embodiment of the present invention, a movable baffle 7 and two partitions constitute a set of material components, and the forming device is equipped with multiple sets of material components.

[0044] In the above embodiments, a plurality of groups of vertical grooves 303 are respectively provided on the left and right walls of the mold 3, and a partition is provided in each group of the vertical grooves 303. The lower end of each group of the partitions has an inward bending portion 302, and a corresponding movable baffle 7 is mounted on the bending portion 302. Each group of partitions and the corresponding movable baffle 7 form a loading cavity with an upper opening, and the loading cavity is filled with asphalt mixture. A movable baffle 7 and two partitions constitute a group of loading components, and the molding device is equipped with a plurality of groups of loading components. In this way, the present invention can mold beam specimens of different widths, broaden the scope of application of the present invention, and break the limitations of traditional cutting beam specimens.

[0045] refer to Figure 1-5 According to one embodiment of the present invention, the lifting unit 2 is a spiral lift, and the upper end of the lifting rod of the spiral lift has a bracket 201, and a semicircular rotating shaft 503 is installed in the bracket 201.

[0046] refer to Figure 3 and 4 According to one embodiment of the present invention, there is a gap between the upper end of the bracket 201 and the lower surface of the support plate 5.

[0047] In the above embodiment, there is a gap between the upper end of the bracket 201 and the lower surface of the support plate 5, so that the support plate 5 can rotate at a small angle along the semicircular rotation axis, and the rotation is limited to avoid it from turning over at a large angle.

[0048] refer to Figure 1 and 6 According to one embodiment of the present invention, a roller 304 is provided on the outer side wall of the mold 3, and a guide rail 305 is provided at the corresponding position of the test bracket 1. The roller 304 moves along the guide rail 305 to move the mold 3 left and right.

[0049] In the above embodiment, a roller 304 is provided on the outer wall of the mold 3, and a guide rail 305 is provided at the corresponding position of the test bracket 1. The roller 304 moves along the guide rail 305, so that when loading is required, the mold 3 only needs to be pulled out, and when pressing the material, it is pushed in, which is convenient for loading and removing materials and saves space for the device.

[0050] refer to Figure 1-5 According to one embodiment of the present invention, the vibration unit 4 includes a vibration motor 401 and a reaction frame 402 , and a mold cover 6 is installed on the reaction plate of the reaction frame 402 .

[0051] In the above embodiment, the lower end of the reaction frame 402 has a horizontal reaction plate, and the mold cover 6 is installed under the reaction plate to ensure the stability of the device during the vibration process. The vibration motor 401 can be installed on the upper end plane of the reaction frame 402 or the test bracket 1 to generate vibration.

[0052] refer to Figure 3 According to an embodiment of the present invention, the heating component 301 is a heating resistance wire.

[0053] In the above embodiments, the heating resistance wire is used to make the asphalt mixture to be pressed reach the required temperature during the pressing process, so as to facilitate the pressing process. At the same time, it is connected to the controller to facilitate temperature control.

[0054] refer to Figure 1-5 According to one embodiment of the present invention, a displacement sensor is installed at the lifting position of the lifting unit 2.

[0055] In the above embodiments, the displacement sensor is used to sense the rising or falling height of the lifting unit 2, and it can also be connected to the controller to control the rising or falling height of the lifting unit 2, which is convenient for controlling the height of the test process.

[0056] In view of the shortcomings of existing mixture molding methods, the present invention designs an asphalt mixture beam vibration molding test device with variable height, adjustable width, no need for cutting, kneading and rolling, which improves the accuracy of asphalt mixture low-temperature cracking performance evaluation and fatigue performance verification test.

[0057] Example 2

[0058] A method for forming a beam specimen of an asphalt mixture comprises the following steps:

[0059] Step 1: according to the width of the beam specimen required for the test, a partition is installed in the corresponding vertical groove, and a corresponding movable baffle is mounted on the partition to form a corresponding loading cavity; and the asphalt mixture to be formed is added into the loading cavity;

[0060] Step 2, turning on the heating component to heat the material to the temperature required for the test; turning on the vibration unit to vibrate and compact the asphalt mixture to be formed in the mold to form a uniform material to be compacted;

[0061] Step 3, turn on the lifting unit to make the bracket move upward with the support plate. When the rolling wheel presses against the movable baffle, under the action of vibration, the rolling wheel and the support plate begin to rotate back and forth to press the movable baffle. When the material on the movable baffle presses against the mold cover, the beam specimen is obtained after continuous pressing for a predetermined time.

[0062] In the above sample preparation process, the limit position of the support plate's forward and backward rotation is that its lower surface abuts against the bracket. The present invention can press beam specimens of different beam heights and beam widths according to test needs, and the obtained beam specimens are dense and uniform, while avoiding stress concentration caused by cutting the specimens, so that the beam specimens obtained by the present invention can more accurately test and verify the low-temperature cracking performance and fatigue performance of asphalt mixtures.

[0063] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A beam specimen forming device for asphalt mixture, characterized in that: include: A test stand, on which a lifting unit, a mold and a vibration unit are arranged from bottom to top; wherein the bottom of the lifting unit is fixed on the test stand, and a support plate is horizontally arranged on the upper end of the lifting unit, and the support plate has a certain thickness; the support plate has multiple groups of wheel grooves on the left and right sides of the upper surface, respectively, and rolling wheels are arranged in the wheel grooves; the upper surface of the support plate has multiple shaft grooves corresponding to each group of wheel grooves, and a fixed shaft is installed in each shaft groove, and the rolling wheel is sleeved on the fixed shaft; the lower surface of the support plate has a semicircular rotating shaft; the upper end of the lifting unit has a bracket matching the semicircular rotating shaft, and the semicircular rotating shaft rotates in the bracket; The mold is a rectangular hollow shell with openings at the upper and lower ends, a mold cover is provided at the upper end of the mold, and a heating component is arranged in the hollow cavity of the shell; the lower ends of the left and right walls of the mold respectively have bending parts, and a movable baffle is mounted on the bending parts, and the movable baffle and the side wall of the mold form a loading cavity, and the asphalt mixture is loaded into the loading cavity; The width of the support plate is smaller than the spacing between each set of bending parts, and when the lifting unit moves upward, the support plate moves upward to make the rolling wheel move upward against the movable baffle; The upper end of the vibration unit is fixed on the test bracket, and the lower end of the vibration unit is installed with a mold cover; A plurality of groups of vertical grooves are respectively provided on the left and right walls of the mold, and a partition is arranged in each group of the vertical grooves. The lower end of each group of the partitions has an inward bending portion, and a corresponding movable baffle is mounted on the bending portion. Each group of the partitions and the corresponding movable baffle form a loading cavity with an upper opening, and the loading cavity is filled with asphalt mixture; The outer side wall of the mold is provided with a roller, and a guide rail is provided at a corresponding position of the test bracket, and the roller moves along the guide rail to move the mold left and right; The vibration unit comprises a vibration motor and a reaction frame, and a mold cover is installed on the reaction plate of the reaction frame.

2. The asphalt mixture beam specimen forming device according to claim 1, characterized in that: A movable baffle and two partitions form a set of material components, and the forming device is equipped with multiple sets of material components.

3. The asphalt mixture beam specimen forming device according to claim 1, characterized in that: The lifting unit is a screw lift, the upper end of the lifting rod of the screw lift is provided with a bracket, and a semicircular rotating shaft is installed in the bracket.

4. The asphalt mixture beam specimen forming device according to claim 3, characterized in that: A gap is formed between the upper end of the bracket and the lower surface of the support plate.

5. The asphalt mixture beam specimen forming device according to claim 1, characterized in that: The heating component is a heating resistance wire.

6. The asphalt mixture beam specimen forming device according to claim 1, characterized in that: A displacement sensor is installed at the lifting position of the lifting unit.

7. A method for forming a beam specimen of an asphalt mixture, characterized in that: The molding method is based on the asphalt mixture beam specimen molding device according to any one of claims 1 to 6, comprising the following steps: Step 1: according to the width of the beam specimen required for the test, a partition is installed in the corresponding vertical groove, and a corresponding movable baffle is mounted on the partition to form a corresponding loading cavity; and the asphalt mixture to be formed is added into the loading cavity; Step 2, turning on the heating component to heat the material to the temperature required for the test; turning on the vibration unit to vibrate and compact the asphalt mixture to be formed in the mold to form a uniform material to be compacted; Step 3: Turn on the lifting unit to move the bracket upward with the support plate. When the baffle is moved, under the action of vibration, the rolling wheel and the support plate begin to rotate back and forth to roll the moving baffle; When the material on the movable baffle plate is pressed against the mold cover, the beam specimen is obtained after continuous rolling for a predetermined time.

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