Performance testing method for asphalt pavement layer, and shearing fixture

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

Asphalt pavement layer performance test method and shearing tool Technical Field

[0001] The present invention relates to the technical field of highway performance testing, and in particular to an asphalt pavement layer performance testing method and a shearing tool. Background Art

[0002] Semi-rigid base pavement accounts for a large proportion of asphalt pavement in highways. Due to the different materials and mechanical properties of the asphalt layer and the semi-rigid base, the bonding performance of the asphalt layer and the semi-rigid base becomes the weak link of the pavement structure. Under the action of repeated loads, the probability of damage increases, seriously affecting the service level and service life of the pavement.

[0003] To ensure good adhesion between the semi-rigid base and the asphalt layer, spraying emulsified asphalt is commonly used as a penetration layer treatment. The penetration layer works by spraying petroleum asphalt, emulsified asphalt, or kerosene asphalt into the semi-rigid base, forming a thin layer. This changes the surface material properties of the semi-rigid base, increasing the adhesion between the semi-rigid base and the asphalt layer, ensuring that vehicle loads are evenly transferred from the asphalt mixture layer to the semi-rigid base. However, due to different aggregate sizes, interface textures, and interface states, the penetration layer and adhesion layer materials all exhibit different working properties, which also affect interfacial adhesion. Currently, there is no method to accurately measure the adhesion between a semi-rigid base and an asphalt layer.

[0004] Therefore, how to design a method that is suitable for construction sites and can accurately test the performance of asphalt pavement bonding layers has become a technical problem that needs to be solved urgently in this field.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to at least solve the problem of how to accurately test the performance of the bonding layer of an asphalt pavement. This purpose is achieved by the following technical solutions:

[0007] In a first aspect, the present invention proposes a method for testing the performance of an asphalt pavement layer, comprising: providing a shear specimen, the shear specimen comprising a laminated water-stabilizing layer, a bonding layer, and an asphalt layer; shearing the bonding layer of the shear specimen at a constant rate by direct shearing; obtaining test data during the shearing process of the bonding layer of the shear specimen, the test data comprising the maximum shear force during the shearing process of the bonding layer of the shear specimen, the shear surface diameter of the bonding layer, and the shear force displacement corresponding to the maximum shear force; and calculating the performance of the shear specimen based on the test data.

[0008] The technical solution of the embodiment of the present application is to first obtain a shear specimen, then adjust the shear spacing, after the shear spacing is adjusted, shear the bonding layer of the shear specimen at a constant rate using a direct shear method, and record the test data. Finally, the performance of the shear specimen is evaluated based on the obtained test data.

[0009] In this embodiment, the performance of the asphalt pavement bonding layer can be evaluated more accurately by setting different shear intervals and performing multiple tests on the shear specimens at different constant rates.

[0010] In some embodiments of the present invention, calculating the performance of the shear specimen based on the test data further includes: calculating the maximum shear stress according to Formula 1 using the maximum shear force and the shear surface diameter, and determining the shear load resistance of the shear specimen based on the maximum shear stress calculated by Formula 1; Formula 1: τ max =4P max / (πD 2 ); where τ max is the maximum shear stress, unit is MPa; P max is the maximum shear force, in N; D is the shear surface diameter, in mm.

[0011] In some embodiments of the present invention, calculating the performance of the shear specimen based on the test data further includes: calculating the maximum shear stiffness according to Formula 2 using the shear force displacement corresponding to the maximum shear force and the maximum shear stress calculated by Formula 1, and determining the deformation resistance of the shear specimen based on the maximum shear stiffness calculated by Formula 2; Formula 2: K max =τ max / L max Among them, K max is the maximum shear stiffness, unit is MPa / mm; L max is the shear force displacement corresponding to the maximum shear force, in mm.

[0012] In some embodiments of the present invention, shearing the bonding layer of the shear specimen at a constant rate by direct shearing includes: adjusting the shear spacing and fixing the shear specimen to the shear fixture; the testing machine applies a force not greater than the set contact load to the shear fixture, so that the shear plate of the shear fixture contacts the shear specimen, and the testing machine drives the shear fixture to perform direct shearing on the bonding layer of the shear specimen at a constant rate; when the contact load between the shear plate and the shear specimen drops to less than the set contact load, the shearing is stopped.

[0013] In some embodiments of the present invention, before shearing the bonding layer of the shear specimen at a constant rate by direct shearing, the method further includes: placing the shear specimen in an environmental box with a set temperature to allow the temperature inside the shear specimen to reach the set temperature.

[0014] In some embodiments of the present invention, providing a shear specimen includes: obtaining a water-stable layer; spraying a permeable layer and a sealing layer on the water-stable layer in sequence, wherein the permeable layer and the sealing layer constitute a bonding layer; and covering the bonding layer with an asphalt layer.

[0015] In some embodiments of the present invention, obtaining the water-stable layer includes: vibrating and compacting the water-stable layer indoors; or drilling the water-stable layer outdoors at a construction site.

[0016] In the second aspect, the present invention proposes a shearing tool, which is suitable for any of the above-mentioned asphalt pavement layer performance test methods, comprising: an installation frame, comprising a base plate; an upper shear assembly, comprising a loading plate and a force transmission rod and an upper shear plate respectively arranged on both sides of the loading plate, the force transmission rod is used to connect to the testing machine, the shearing portion of the upper shear plate matches the edge of the shear specimen, and the upper shear plate can move in a direction perpendicular to the base plate; and a lower shear assembly, comprising a telescopic shear plate and a pressure plate fixedly connected to the telescopic shear plate, the telescopic shear plate comprises a fixed plate and a lower shear plate, the fixed plate is fixedly connected to the base plate, the lower shear plate can move relative to the fixed plate in a first direction, the first direction is parallel to the base plate, the shearing portion of the lower shear plate matches the edge of the shear specimen, and the pressure plate is used to cooperate with the telescopic shear plate to press the shear specimen.

[0017] In some embodiments of the present invention, the mounting frame further includes: a guide rod vertically mounted on the base plate, the guide rod being used to guide the loading plate to move in a direction perpendicular to the base plate; a crossbeam fixedly mounted on the end of the guide rod facing away from the base plate, the crossbeam being located on the side of the loading plate facing away from the base plate, the crossbeam having a through hole for passing a force transmission rod, a first magnet being provided on the side of the crossbeam close to the base plate, and a second magnet being provided on the side of the loading plate facing away from the base plate that attracts the first magnet.

[0018] In some embodiments of the present invention, the fixed plate is connected to the lower shear plate through a connecting rod, and the connecting rod extends along a first direction; the first end of the connecting rod is fixedly connected to the lower shear plate; the fixed plate has a mounting groove and a mounting hole, the mounting hole is used to pass the connecting rod and is connected to the mounting groove, and the second end of the connecting rod has a threaded portion, and the threaded portion is fixed to the fixed plate by an inner nut and an outer nut, the inner nut is located in the mounting groove, and the outer nut is located on the outer wall of the mounting groove.

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference numerals are used throughout the accompanying drawings to denote the same components. In the accompanying drawings:

[0021] FIG1 is a flow chart of a method for testing asphalt pavement performance according to an embodiment of the present invention;

[0022] FIG2 is a shear spacing-maximum shear force curve diagram in the asphalt pavement layer performance testing method provided by an embodiment of the present invention;

[0023] FIG3 is a shear rate-maximum shear force curve diagram of the asphalt pavement layer performance testing method provided by an embodiment of the present invention;

[0024] FIG4 is a schematic structural diagram of a shearing fixture provided by an embodiment of the present invention when a shearing specimen is installed;

[0025] FIG5 is a schematic structural diagram of an installation frame in a shearing tool provided in an embodiment of the present invention;

[0026] FIG6 is a schematic structural diagram of an upper shearing assembly in a shearing tool provided in an embodiment of the present invention;

[0027] FIG7 is a schematic diagram of a portion of the structure of the lower shearing assembly in the shearing tool provided in an embodiment of the present invention.

[0028] The reference numerals are as follows:

[0029] 10. Shearing tooling

[0030] 1. Mounting frame; 11. Base plate; 12. Guide rod; 13. Crossbeam; 131. Through hole; 132. Threaded hole; 14. Screw; 15. Screw; 16. Washer; 17. Spacer; 18. Mounting nut;

[0031] 2. Upper shear assembly; 21. Loading plate; 211. Guide groove; 212. Second magnet; 22. Force transmission rod; 23. Upper shear plate;

[0032] 3. Lower shear assembly; 31. Telescopic shear plate; 311. Fixed plate; 3111. Mounting slot; 312. Lower shear plate; 32. Press plate; 33. Connecting rod; 34. Nut assembly; 341. Inner nut; 342. Outer nut; 35. Joint bolt; 36. Rotating shaft; 37. Fastening nut; 38. Groove; 39. Butterfly nut;

[0033] 4. Cut the specimen. DETAILED DESCRIPTION

[0034] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0035] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0036] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0037] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside," "outside," "inside," "outside," "below," "beneath," "above," and the like. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is flipped, an element described as "below" or "below" another element or feature would then be oriented as "above" or "above" another element or feature. Thus, the example term "below" can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are interpreted accordingly.

[0038] FIG1 is a flow chart of a method for testing the performance of an asphalt pavement layer provided by an embodiment of the present invention. As shown in FIG1 , the embodiment of the present application provides a method for testing the performance of an asphalt pavement layer, including:

[0039] Providing a shear test specimen, the shear test specimen includes a laminated water-stabilizing layer, a bonding layer, and an asphalt layer;

[0040] The bonding layer of the shear specimen is sheared at a constant rate by direct shearing;

[0041] Acquiring test data during the shearing process of the adhesive layer of the shear specimen, the test data including the maximum shear force during the shearing process of the adhesive layer of the shear specimen, the shear surface diameter of the adhesive layer, and the shear force displacement corresponding to the maximum shear force;

[0042] Based on the test data, calculate the properties of the shear specimen.

[0043] In this embodiment, a shear specimen is first obtained, and then the shear spacing is adjusted. After the shear spacing is adjusted, the bonding layer of the shear specimen is sheared at a constant rate using a direct shear method. The test data is recorded during the shearing process, and finally the performance of the shear specimen is evaluated based on the obtained test data.

[0044] The shear spacing is defined as the distance between the shear plates on the upper and lower sides of the shear specimen, perpendicular to the shear plane. The shear displacement is defined as the distance the shear plates move parallel to the shear plane during direct shear.

[0045] In addition, the maximum shear force and the shear force displacement corresponding to the maximum shear force can be determined by plotting a shear force-shear force displacement curve during the shearing process. As for the diameter of the shear surface, the diameter of the shear surface can be measured with a vernier caliper before conducting the direct shear test, and then calculated. The diameter of the shear surface can be measured four times in a cross-sectional manner, and the average value is calculated and recorded. It should be noted that the method for measuring the shear surface diameter in this embodiment is only for illustration, and the specific measuring instrument, measurement method, and number of measurements can be determined according to actual needs and are not limited.

[0046] FIG2 is a shear spacing-maximum shear force curve diagram in the asphalt pavement layer performance test method provided by an embodiment of the present invention; FIG3 is a shear rate-maximum shear force curve diagram in the asphalt pavement layer performance test method provided by an embodiment of the present invention. Referring to FIG2 and FIG3, specifically, for example, four gradually increasing shear spacings of 2 mm, 6 mm, 10 mm and 14 mm are first set, and direct shear tests are performed at a shear rate of 3 mm / min. The shear spacing-maximum shear force curve is drawn, as shown in FIG2. It can be found that when the shear spacing increases to 10 mm, the curve gradually becomes flat; then the shear spacing is set to 10 mm. Direct shear tests were conducted at four gradually increasing shear rates of 1 mm / min, 3 mm / min, 5 mm / min, and 7 mm / min at a shear spacing of 10 mm. The shear rate-maximum shear force curve was plotted, as shown in Figure 3. It can be found that when the shear rate increases to 5 mm / min, the curve gradually becomes flat. Therefore, when evaluating the performance of the asphalt pavement bonding layer, the shear spacing of 10 mm and the shear rate of 5 mm / min can be selected to test the shear specimens to ensure the stability of the test results, so as to more accurately evaluate the performance of the asphalt pavement bonding layer.

[0047] Therefore, the method of this embodiment can more accurately evaluate the performance of the asphalt pavement bonding layer by setting different shear intervals and performing multiple tests on the shear specimens at different constant rates.

[0048] According to an optional embodiment of the present application, calculating the performance of the shear specimen further includes: calculating the maximum shear stress according to Formula 1 using the maximum shear force and the shear surface diameter, and determining the shear load resistance of the shear specimen according to the maximum shear stress calculated by Formula 1;

[0049] Formula 1: τ max =4P max / (πD 2 );

[0050] Among them, τ max is the maximum shear stress, unit is MPa; P max is the maximum shear force, in N; D is the shear surface diameter, in mm;

[0051] In this embodiment, since the maximum shear force can be obtained during the direct shear test and the shear surface diameter can also be measured before the direct shear test, the maximum shear stress that the shear specimen withstands in the direct shear test can be calculated by formula 1. The larger the maximum shear stress, the better the bonding performance of the bonding layer of the shear specimen and the better its ability to resist the shear load.

[0052] Therefore, the method of this embodiment can accurately evaluate the bonding performance of the bonding layer of the shear specimen.

[0053] According to an optional embodiment of the present application, calculating the performance of the shear specimen further includes:

[0054] The maximum shear stiffness is calculated according to Formula 2 using the shear force displacement corresponding to the maximum shear force and the maximum shear stress calculated by Formula 1. The deformation resistance of the shear specimen is determined based on the maximum shear stiffness calculated by Formula 2.

[0055] Formula 2: K max =τ max / L max ;

[0056] Among them, K max is the maximum shear stiffness, unit is MPa / mm; L max is the shear force displacement corresponding to the maximum shear force, in mm.

[0057] In this embodiment, since the shear force displacement corresponding to the maximum shear force can be obtained during the direct shear test, and the maximum shear stress has been calculated by Formula 1, the maximum shear stiffness of the shear specimen can be calculated by Formula 2. The greater the maximum shear stiffness, the less likely the bonding layer of the shear specimen is to deform or slip under the action of the shear load.

[0058] Therefore, the method of this embodiment can accurately evaluate the deformation resistance and slippage ability of the bonding layer of the shear specimen.

[0059] According to an optional embodiment of the present application, shearing the bonding layer of the shear specimen at a constant rate by direct shearing includes:

[0060] Adjust the shear spacing and fix the shear specimen on the shear fixture;

[0061] The testing machine applies a force no greater than the set contact load to the shear fixture, causing the shear plate of the shear fixture to contact the shear specimen. The testing machine drives the shear fixture to perform direct shearing on the bonding layer of the shear specimen at a constant rate.

[0062] When the contact load between the shear plate and the shear specimen drops below the set contact load, shearing stops.

[0063] In this embodiment, after the shear spacing is adjusted, the shear specimen is fixed to the shear fixture to facilitate the adjustment of the shear spacing; in addition, when the shear specimen is subjected to direct shear, the shear force and shear force displacement during the test are recorded, and shearing is performed continuously until the shear force reaches the maximum value, after which the shear force decreases rapidly. When the load drops to the set contact load, the shearing is stopped.

[0064] The contact load may be 80N-120N, for example, 100N. It should be noted that the range of the contact load in this embodiment is only for illustration and may be determined according to actual needs without limitation.

[0065] According to an optional embodiment of the present application, before shearing the bonding layer of the shear specimen at a constant rate by direct shearing, the method further includes:

[0066] Place the shear specimen in an environmental chamber with a set temperature so that the temperature inside the shear specimen reaches the set temperature.

[0067] For example, the set temperature may be 25°C, and the temperature in the environmental chamber should be within (25±0.2)°C to prevent excessive temperature deviation.

[0068] In this embodiment, the internal temperature of the shear specimen is ensured to be consistent before the shear test, so that the variables in evaluating the performance of the asphalt pavement bonding layer can be more uniform, resulting in more accurate evaluation results.

[0069] According to an optional embodiment of the present application, obtaining a shear test piece includes:

[0070] Obtaining a water-stabilizing layer;

[0071] The permeable layer and the sealing layer are sprayed on the water-stabilizing layer in sequence, and the permeable layer and the sealing layer constitute a bonding layer; the asphalt layer is covered on the bonding layer.

[0072] In this embodiment, the permeable layer is an emulsified asphalt permeable layer, and the sealing layer includes a hot asphalt chip seal layer.

[0073] Specifically, covering the asphalt layer on the bonding layer includes:

[0074] The specimen sample (i.e. the formed water-stabilizing layer and bonding layer) is placed with the bonding layer facing upward in the test mold of the rotary compactor, covered with hot asphalt mixture, and then demolded after rotary compaction. After cooling at room temperature, a shear specimen is formed.

[0075] The diameter of the test mold is typically 150 mm, the hot asphalt mixture can be AC-20 hot asphalt mixture, the coverage height can be 40 mm ± 1 mm, and the room temperature cooling time can be 24 hours. Similarly, the specific dimensions, materials, and time in this embodiment are for illustration only and can be determined based on actual needs without limitation.

[0076] According to an optional embodiment of the present application, obtaining the water-stabilizing layer includes: vibrating and compacting the water-stabilizing layer indoors; or drilling the water-stabilizing layer at an outdoor construction site.

[0077] In this embodiment, specifically, when the water-stabilizing layer, the permeable layer and the sealing layer are manufactured indoors, the steps include:

[0078] Vibration compaction to form a subaqueous stabilizing layer with a height of 148mm±2mm;

[0079] One day later, evenly spray the emulsified asphalt penetration layer at a rate of 1kg / m 2 ;

[0080] After curing in a standard water-stabilized curing room for 20-30 days, for example 28 days, the test specimens are cut into cylinders with a diameter of 100 mm to 150 mm, and then evenly sprayed with hot asphalt chip seal.

[0081] When making the water-stabilizing layer, permeable layer and sealing layer outdoors, the steps include:

[0082] On-site drilling of water-stabilizing layer;

[0083] After the water-stabilizing layer is paved and rolled, spray the emulsified asphalt penetration layer;

[0084] After the emulsified asphalt penetration layer breaks, continue to spread the slurry seal or hot asphalt seal;

[0085] After curing for 5-10 days, for example, 7 days, drill out specimens with a diameter of 100mm±2mm or 150mm±2mm. Ensure that the edges and corners of the sealing surface and the interface between layers of the specimens are intact without particle loss. Cut the specimens into cylinders with a height of 100mm±5mm.

[0086] Therefore, the method provided in this embodiment can not only directly drill the water-stabilizing layer on site to produce shear specimens, but also produce shear specimens separately indoors; it can not only perform performance tests on asphalt pavements that have been formed and put into use, but also perform performance tests on construction materials before paving, thereby ensuring the performance of construction materials from the source and ensuring the quality of the subsequently formed asphalt pavement.

[0087] It should be noted that the dimensions and curing time in this embodiment are only examples and can be determined according to actual needs without limitation.

[0088] FIG4 is a schematic structural diagram of a shearing fixture provided in an embodiment of the present invention when an upper shear specimen is installed; FIG5 is a schematic structural diagram of an installation frame in a shearing fixture provided in an embodiment of the present invention; FIG6 is a schematic structural diagram of an upper shear assembly in a shearing fixture provided in an embodiment of the present invention; FIG7 is a schematic structural diagram of a portion of a lower shear assembly in a shearing fixture provided in an embodiment of the present invention; Referring to FIG4-FIG7, an embodiment of the present application further provides a shearing fixture 10, which is suitable for any of the above-mentioned asphalt pavement layer performance test methods, comprising: a mounting frame 1, comprising a base plate 11; an upper shear assembly 2, comprising a loading plate 21 and a force transmission rod 22 and an upper shear plate 23 respectively arranged on both sides of the loading plate 21 The force transmission rod 22 is used to connect with the testing machine, the shearing portion of the upper shear plate 23 matches the edge of the shear specimen 4, and the upper shear plate 23 can move in a direction perpendicular to the substrate 11; and the lower shear assembly 3, including a telescopic shear plate 31 and a pressure plate 32 fixedly connected to the telescopic shear plate 31, the telescopic shear plate 31 includes a fixed plate 311 and a lower shear plate 312, the fixed plate 311 is fixedly connected to the substrate 11, the lower shear plate 312 can move relative to the fixed plate 311 in a first direction, the first direction is parallel to the substrate 11, the shearing portion of the lower shear plate 312 matches the edge of the shear specimen 4, and the pressure plate 32 is used to cooperate with the telescopic shear plate 31 to press the shear specimen 4.

[0089] In this embodiment, when this shearing fixture 10 performs a direct shear test on the shear specimen 4, the shearing fixture 10 is first installed on the testing machine, and the force transmission rod 22 is connected to the testing machine, and the assembly is completed; before shearing, the relative position between the lower shear plate 312 and the fixed plate 311 is adjusted along the first direction, that is, the distance between the lower shear plate 312 and the upper shear plate 23 is adjusted along the first direction, so as to adjust the shear spacing; after the shear spacing is adjusted, the shear specimen 4 is fixed between the pressure plate 32 and the telescopic shear plate 31; during shearing, the testing machine is started, and the testing machine drives the force transmission rod 22 to drive the upper shear assembly 2 to move downward to achieve contact between the shearing portion of the upper shear plate 23 and the edge of the shear specimen 4, and the direct shear test is continued at a constant rate.

[0090] In this shearing tool 10, since the upper shear plate 23 moves vertically relative to the base plate 11, and the lower shear plate 312 can move relative to the fixed plate 311 along the first direction, and the fixed plate 311 is fixedly connected to the base plate 11, the shearing spacing can be adjusted by simply adjusting the relative position between the lower shear plate 312 and the fixed plate 311 along the first direction.

[0091] 4 and 7 , the pressure plate 32 is fixed to the telescopic shear plate 31 via a flexible bolt 35. A rotating shaft 36 is provided on either side of the fixed plate 311, the axis of which extends in a first direction. Two flexible bolts 35 are perpendicularly connected to the two rotating shafts 36, respectively, and each rotating shaft 36 is provided with a corresponding fastening nut 37 to secure the position of the flexible bolts 35. A recess 38 is provided on either side of the pressure plate 32 for accommodating the flexible bolts 35, which are secured to the recesses 38 by butterfly nuts 39. Specifically, when the shear specimen 4 needs to be fixedly installed, the shear specimen 4 is placed on the side of the telescopic shear plate 31 facing away from the base plate 11. The pressure plate 32 is then placed above the shear specimen 4. The flexible bolts 35 are rotated until they are perpendicular to the base plate 11 and are secured within the recesses 38. The fastening nuts 37 and butterfly nuts 39 are then tightened to secure the shear specimen 4 between the pressure plate 32 and the telescopic shear plate 31.

[0092] In addition, for a cylindrical shear specimen 4, the side of the pressing plate 32 that contacts the shear specimen 4, the shearing portion of the upper shear plate 23, the shearing portion of the lower shear plate 312, and the side of the fixing plate 311 facing away from the base plate 11 can be made into curved surfaces, as shown in Figures 6 and 7, to match the edge of the shear specimen 4, thereby achieving more precise fixing and shearing of the shear specimen 4. It should be noted that this embodiment is only an example of a feasible method, and the shape, size, and curvature of the pressing plate 32, the upper shear plate 23, the lower shear plate 312, and the fixing plate 311 are not specifically limited and can be determined according to actual needs to be suitable for different shear specimens 4.

[0093] In addition, the fixing plate 311 can be connected to the base plate 11 by screws to facilitate subsequent maintenance and replacement.

[0094] Referring to Figures 4 to 6, according to an optional embodiment of the present application, the mounting frame 1 further includes: a guide rod 12, mounted perpendicularly to the base plate 11, the guide rod 12 being used to guide the loading plate 21 to move in a direction perpendicular to the base plate 11; a crossbeam 13, fixedly mounted on the end of the guide rod 12 facing away from the base plate 11, the crossbeam 13 being located on the side of the loading plate 21 facing away from the base plate 11, the crossbeam 13 having a through hole 131 for passing the force transmission rod 22, a first magnet (not shown) being provided on the side of the crossbeam 13 close to the base plate 11, and a second magnet 212 being provided on the side of the loading plate 21 facing away from the base plate 11, which attracts the first magnet. A guide groove 211 is provided on the loading plate 21 for accommodating the guide rod 12. When the upper shear assembly 2 moves downward as a whole, sliding friction is generated between the guide groove 211 and the guide rod 12.

[0095] There can be two guide rods 12, arranged along a second direction parallel to the base plate 11 and perpendicular to the first direction. Along the second direction, a guide slot 211 is provided on each side of the loading plate 21. Multiple first and second magnets 212 can also be provided, for example, two second magnets 212 are provided in FIG6 , to further enhance the stability of the mutual attraction between the crossbeam 13 and the loading plate 21.

[0096] In addition, as shown in FIG5 , a screw 15 may be provided at one end of the guide rod 12 away from the base plate 11. A threaded hole 132 is provided on the crossbeam 13 to mate with the screw 15. The crossbeam 13 is secured to the screw 15 via a mounting nut 18. A washer 16 and a spacer 17 may be provided between the mounting nut 18 and the threaded hole 132. The guide rod 12 and the base plate 11 may be connected via screws 14 to facilitate subsequent maintenance and replacement.

[0097] In this embodiment, the crossbeam 13 is arranged so that the loading plate 21 can be adsorbed on the crossbeam 13 before fixing the shear specimen 4, thereby providing space for the installation of the shear specimen 4. When performing a direct shear test, the force applied by the testing machine to the force transmission rod 22 can overcome the suction force between the first magnet and the second magnet 212, thereby realizing the overall downward movement of the upper shear assembly 2 to shear the shear specimen 4. This method of detachably connecting the crossbeam 13 and the loading plate 21 through the first magnet and the second magnet 212 is simple and convenient to operate, further improving the assembly and working efficiency of the shear tooling 10.

[0098] The setting of the guide rod 12, when the upper shear assembly 2 moves downward as a whole, can guide the movement of the upper shear assembly 2 due to the existence of the guide rod 12, effectively preventing the upper shear plate 23 from having path deviation during movement, thereby ensuring the effectiveness of the shear spacing and improving the accuracy of the direct shear test.

[0099] As shown in Figure 7, according to an optional embodiment of the present application, the fixed plate 311 is connected to the lower shear plate 312 through a connecting rod 33, and the connecting rod 33 extends along a first direction; the first end of the connecting rod 33 is fixedly connected to the lower shear plate 312; the fixed plate 311 has a mounting groove 3111 and a mounting hole, the mounting hole is used to pass the connecting rod 33 and is connected to the mounting groove 3111, the second end of the connecting rod 33 has a threaded portion, and the threaded portion is fixed to the fixed plate 311 by a nut assembly 34, the inner nut 341 is located in the mounting groove 3111, and the outer nut 342 is located on the outer wall of the mounting groove 3111.

[0100] In this embodiment, when the shearing distance needs to be adjusted, the lower shear plate 312 is first moved along the first direction until the shearing distance is adjusted appropriately, and the second end of the connecting rod 33 is locked to the mounting groove 3111 by the inner nut 341 and the outer nut 342. At this time, the relative position of the lower shear plate 312 and the fixed plate 311 is fixed, and the shearing distance adjustment is completed.

[0101] This arrangement facilitates adjustment of the shear spacing and is simple and convenient to operate. It ensures the connection stability between the lower shear plate 312 and the fixed plate 311 while improving the efficiency of shear spacing adjustment.

[0102] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for testing the performance of an asphalt pavement layer, characterized in that: include: Providing a shear specimen, wherein the shear specimen includes a water-stabilizing layer, a bonding layer, and an asphalt layer that are stacked; Shearing the bonding layer of the shear specimen at a constant rate by direct shearing; Acquiring test data during the shearing process of the adhesive layer of the shear specimen, the test data including a maximum shear force during the shearing process of the adhesive layer of the shear specimen, a shear surface diameter of the adhesive layer, and a shear force displacement corresponding to the maximum shear force; The performance of the shear specimen is calculated based on the test data.

2. The asphalt pavement layer performance testing method according to claim 1, characterized in that: Calculating the performance of the shear specimen based on the test data includes: calculating the maximum shear stress according to Formula 1 using the maximum shear force and the shear surface diameter, and determining the shear load resistance of the shear specimen based on the maximum shear stress calculated by Formula 1; Formula 1: τ max = 4P max / (πD 2 ); Among them, τ max is the maximum shear stress, unit is MPa; P max is the maximum shear force, in N; D is the shear surface diameter, in mm.

3. The asphalt pavement layer performance testing method according to claim 2, characterized in that: Calculating the performance of the shear specimen based on the test data further includes: calculating the maximum shear stiffness according to Formula 2 using the shear force displacement corresponding to the maximum shear force and the maximum shear stress calculated by Formula 1, and determining the deformation resistance of the shear specimen based on the maximum shear stiffness calculated by Formula 2; Formula 2: K max =τ max / L max； Among them, K max is the maximum shear stiffness, unit is MPa / mm; L max is the shear force displacement corresponding to the maximum shear force, in mm.

4. The asphalt pavement performance testing method according to claim 1, characterized in that: The shearing of the bonding layer of the shear specimen at a constant rate by direct shearing includes: Adjust the shearing distance and fix the shear specimen on the shearing fixture; The testing machine applies a force no greater than a set contact load to the shearing fixture, causing the shear plate of the shearing fixture to contact the shear specimen, and the testing machine drives the shearing fixture to perform direct shearing on the bonding layer of the shear specimen at a constant rate; When the contact load between the shear plate and the shear specimen drops to less than the set contact load, shearing is stopped.

5. The asphalt pavement layer performance testing method according to claim 1, characterized in that: Before shearing the bonding layer of the shear specimen at a constant rate by direct shearing, the method further comprises: The shear test piece is placed in an environmental box with a set temperature, so that the temperature inside the shear test piece reaches the set temperature.

6. The asphalt pavement layer performance testing method according to any one of claims 1 to 5, characterized in that: Providing a shear test piece comprises: Obtaining a water-stabilizing layer; The permeable layer and the sealing layer are sprayed on the water-stabilizing layer in sequence, and the permeable layer and the sealing layer constitute the bonding layer. layer; The asphalt layer is covered on the bonding layer.

7. The asphalt pavement layer performance testing method according to claim 6, characterized in that: The obtaining of the water-stable layer comprises: Indoor vibration compaction molding of the water-stable layer; or The water-stabilizing layer is drilled at an outdoor construction site.

8. A shearing tool, suitable for the asphalt pavement layer performance testing method according to any one of claims 1 to 7, characterized in that: include: mounting frame, including baseplate; An upper shear assembly, comprising a loading plate, and force transmission rods and an upper shear plate respectively disposed on both sides of the loading plate, wherein the force transmission rods are used to connect to the testing machine, the shearing portion of the upper shear plate matches the edge of the shear specimen, and the upper shear plate is capable of moving in a direction perpendicular to the base plate; and The lower shear assembly includes a telescopic shear plate and a pressure plate fixedly connected to the telescopic shear plate. The telescopic shear plate includes a fixed plate and a lower shear plate. The fixed plate is fixedly connected to the base plate. The lower shear plate can move relative to the fixed plate along a first direction. The first direction is parallel to the base plate. The shearing portion of the lower shear plate matches the edge of the shear specimen. The pressure plate is used to cooperate with the telescopic shear plate to press the shear specimen.

9. The shearing tool according to claim 8, characterized in that: The mounting frame further comprises: a guide rod, mounted vertically on the base plate, the guide rod being used to guide the loading plate to move in a direction perpendicular to the base plate; and A crossbeam is fixedly mounted on one end of the guide rod facing away from the base plate. The crossbeam is located on the side of the loading plate facing away from the base plate. The crossbeam has a through hole for passing the force transmission rod. A first magnet is provided on the side of the crossbeam close to the base plate. A second magnet that attracts the first magnet is provided on the side of the loading plate facing away from the base plate.

10. The shearing tool according to claim 8 or 9, characterized in that: The fixing plate is connected to the lower shear plate via a connecting rod, and the connecting rod extends along a first direction; The first end of the connecting rod is fixedly connected to the lower shear plate; The fixing plate has a mounting groove and a mounting hole, the mounting hole is used to pass the connecting rod and is connected to the mounting groove, the second end of the connecting rod has a threaded portion, and the threaded portion is fixed to the fixing plate by an inner nut and an outer nut, the inner nut is located in the mounting groove, and the outer nut is located on the outer wall of the mounting groove.