A method and device for asphalt-aggregate interface pull-off experiments

Abstract

The application provides a bitumen-aggregate interface pulling experiment method and device, and relates to the technical field of pulling experiments.The method first uses a calibration piece with known axial stiffness to reproduce the formal pulling force transmission path, and establishes a system deformation curve;then clamps the test piece and implements displacement control pulling, uses system deformation to correct the measured displacement, adaptively adjusts the loading speed and sampling frequency according to the real-time stiffness change, and combines the post-peak load ratio with the corrected work increment to form an objective termination condition;finally, the interface bonding strength and the corrected adhesion work are calculated.The device comprises a universal testing machine, a pulling clamp, a calibration piece and a data processing controller.The application is beneficial to reducing the errors introduced by the system flexibility and the termination point difference, and improving the comparability and traceability of the experimental data.

Description

Technical Field

[0001] This invention relates to the field of pull-out testing technology, and more specifically, to a pull-out test method and apparatus for the asphalt-aggregate interface. Background Technology

[0002] The interfacial bond state between asphalt and aggregate affects the load-bearing capacity, durability, and anti-stripping properties of asphalt mixtures. Pull-out tests typically involve placing the asphalt sample between a pull-out member and the aggregate matrix, then applying a tensile load along the interface normal using a universal testing machine. The interfacial performance is evaluated through peak load and load-displacement curves. This method is intuitive and can be used to compare different asphalt materials, mastic, or aggregate surface systems.

[0003] In existing pull-out tests, the displacement recorded by the universal testing machine typically includes the combined deformation of the frame, loading end, clamps, connection points, and other load-bearing components, and is not entirely equivalent to the relative pull-out displacement of the asphalt-aggregate interface. If the total displacement is directly used to calculate the interfacial adhesion work, the work corresponding to the deformation of the experimental system may also be included, making it difficult to directly compare results under different clamp conditions or equipment conditions. Conventional constant-speed loading also makes it difficult to balance the efficiency of the early experimental stages with the data resolution near and after the peak. Regarding pull-out termination, using observation-dependent descriptions such as "complete interface failure" is prone to differences in termination timing due to different operator judgments. Using a load reduction to a certain percentage as the termination condition alone may be affected by instantaneous fluctuations or prematurely stopped before the energy dissipation curve has stabilized.

[0004] Therefore, it is necessary to provide a method and apparatus for a pull-out test of the asphalt-aggregate interface to solve the above problems. Summary of the Invention

[0005] This invention aims to solve the problems in pull-out experiments where measuring the total displacement includes the deformation of the experimental system, and it is difficult to balance efficiency and data density at critical stages with a constant loading speed, as well as the reliance on subjective judgment for experiment termination.

[0006] To address the above problems, this invention provides a pull-out test method for the asphalt-aggregate interface, comprising the following steps: S1, with axial stiffness as The calibration components were installed according to the force transmission path of the formal pull-out, and the total displacement was measured and calibrated by applying loads in stages. ,according to

[0007] Establish system deformation curves; S2. The pull-out force transmission spindle is connected to the substrate test block of the asphalt to be tested. The substrate test block is clamped by the upper limit pressure plate and the support block. The upper loading end of the universal testing machine clamps the pull-out force transmission spindle, and the lower loading end clamps the centering screw. S3. Pulling out using displacement control, collecting the data. Load at each sampling point and measuring total displacement ,according to

[0008] Obtain the corrected pull-out displacement; S4. Calculate the real-time stiffness from the load and the corrected pull-out displacement, determine the reference stiffness with the initial loading segment stiffness, and reduce the displacement loading speed when the real-time stiffness continuously decreases relative to the reference stiffness to a preset level. S5. When the ratio of load to peak load is not greater than the preset ratio and the state in which the incremental correction work in the preset sampling window is not greater than the preset threshold for a preset number of consecutive times, the pull-out is terminated. The interface bond strength and the correction adhesion work are calculated based on the maximum load, the effective coverage area of ​​the asphalt to be tested and the load-correction pull-out displacement data. in, The sampling point number, To calibrate the axial stiffness of the component, For the calibration component itself in Axial deformation under load, For load The total displacement under calibration, For system deformation, To measure the total displacement, For the first Load at each sampling point To correct the pull-out displacement.

[0009] The present invention provides a pull-out test method for the asphalt-aggregate interface, which, compared with the prior art, has the following beneficial effects, but is not limited to: To address the challenges in pull-out tests, where measuring total displacement includes system deformation, constant loading speed makes it difficult to balance efficiency with data density at critical stages, and experimental termination relies on subjective judgment, this experimental method first checks the universal testing machine, upper and lower loading ends, and pull-out fixtures to ensure proper fit of locking screws, nuts, centering screws, support blocks, and washers. A calibration component with known axial stiffness is installed at the same force transmission position as the test specimen. Predetermined load levels are applied incrementally, recording the load and total calibration displacement. The processor subtracts the calibration component's own deformation from the total calibration displacement, generating a load-system deformation curve. After calibration, the calibration component is removed. The pull-out force transmission spindle is connected to the substrate specimen via the asphalt to be tested. The substrate specimen is clamped between the upper limit plate and the support block. The upper and lower loading ends respectively clamp the pull-out force transmission spindle and the centering screw. After zeroing, displacement-controlled pull-out is initiated. The data processing controller acquires the load and measures the total displacement point by point, queries the system deformation curve, and calculates and corrects the pull-out displacement. During loading, stiffness is calculated in real time, and the speed and sampling frequency are adjusted according to the continuous decrease in stiffness. After the peak, the peak load, cumulative corrected work, and incremental corrected work within the window are calculated synchronously. The loading stops only when the load decay and energy convergence conditions are continuously met. Finally, the interfacial bond strength is calculated from the maximum load and effective coverage area, and the corrected adhesive work is obtained by integrating the load-corrected pull-out displacement curve. In this process, the calibration component is subjected to graded loading under the same clamping state and force transmission path as the actual pull-out, and the axial deformation of the calibration component itself is deducted to obtain the comprehensive deformation of the experimental system as the load changes. In the actual experiment, the system deformation is deducted from the total measured displacement, which helps to make the displacements involved in the stiffness and adhesive work calculations closer to the actual relative displacement of the interface under test. Furthermore, the real-time stiffness is calculated using the load-displacement data after system flexibility correction, and the loading speed is reduced and the sampling frequency is increased when the real-time stiffness continuously decreases relative to the initial reference stiffness, which can maintain experimental efficiency in the initial stage. Increasing data density near the peak and during the post-peak softening phase reduces erroneous adjustments caused by single-point fluctuations. Simultaneously, combining the attenuation of the current load relative to the operating peak load with the convergence of the cumulative corrected work within the sampling window, and requiring termination of pull-out only after both conditions are continuously met, transforms the subjective condition of "complete interface failure" into a calculable and verifiable objective termination condition. This facilitates the complete preservation of effective post-peak curves and unifies the termination criteria for different experiments. Calculating interface bond strength, corrected adhesion work, and corrected adhesion work per unit effective coverage area on the same data chain allows each index to be traced back to the original load, total displacement, system deformation, and control state, thereby significantly improving the comparability and traceability of experimental results.

[0010] Further, in step S2, the substrate test block is placed centered on the support block. The upper limit pressure plate is provided with a pull-out port. The upper limit pressure plate and the lower bearing pressure plate are connected by multiple locking screws. A nut is provided below the lower bearing pressure plate and threadedly connected to the locking screw. A washer is provided between the support block and the lower bearing pressure plate, so that the pull-out force transmission spindle passes through the pull-out port. The nuts located below the lower bearing pressure plate are tightened sequentially in a diagonal alternating order, so that the lower bearing pressure plate moves towards the upper limit pressure plate along each locking screw and compresses the washer until the substrate test block is clamped. The upper loading end and the lower loading end clamp the pull-out force transmission spindle and the centering screw respectively. The installation position is adjusted so that the axis of the pull-out force transmission spindle, the center of the effective coverage area of ​​the asphalt to be tested, the center of the substrate test block, and the axis of the centering screw are all on the same vertical loading axis. After the load and displacement are cleared to zero, step S3 is executed.

[0011] Furthermore, in step S1, the calibration component is subjected to graded loading using the same nut tightening sequence, clamping position, zeroing method, and loading range as the actual pulling process; the calibration component itself is under load The axial deformation below is ,and For loads between adjacent calibration load points, interpolation is performed using the experimental system deformation corresponding to the adjacent calibration load points to obtain the load corresponding to the specified value. .

[0012] Furthermore, in step S5, according to

[0013] Calculate the corrected adhesion work, and according to

[0014] Calculate the adhesive work corrected for the effective coverage area per unit; in, To correct the adhesion work, This represents the total number of sampling points during the pulling process. and The first The and the first Load at each sampling point and The first The and the first Corrected pull-out displacement at each sampling point The effective coverage area of ​​the asphalt to be tested. The adhesive work is corrected per unit effective coverage area, and the load and corrected pull-out displacement are calculated according to the sampling time sequence.

[0015] Furthermore, in step S4, according to

[0016] Calculate the first Real-time stiffness of each stiffness determination window and based on the real-time stiffness of each segment within the initial loading phase. The median is used as the reference stiffness. ; when The state appears continuously When applying a stiffness determination window, the displacement loading speed is changed from... Down to And the sampling frequency was changed from Increase to ;in, The number of sampling intervals included in the stiffness determination window and , The stiffness reduction threshold is greater than 0 and less than 1. To preset the number of consecutive windows, and The displacement loading speeds before and after adjustment are respectively. , and The sampling frequencies before and after adjustment are respectively. .

[0017] Furthermore, in step S5, according to

[0018] Determine as of the date Peak operating load at each sampling point ,according to

[0019] Determine as of the date The cumulative correction power of each sampling point and in According to

[0020] Determine the increment of the correction work; when and The state appears continuously The pulling process was terminated at each sampling point. in, The sampling point number in the cumulative summation. The number of sampling intervals included in the preset sampling window. The load proportion threshold is greater than 0 and less than 1. The energy threshold is greater than 0 and less than 1. To prevent the default positive number with a denominator of zero, To preset the number of consecutive sampling points, This is the function for finding the maximum value.

[0021] Furthermore, in step S5, according to

[0022] Calculate the interfacial bond strength; in, For interfacial bond strength, This represents the maximum load during the pull-out process. The effective coverage area formed between the bottom end of the pull-out force-transmitting spindle and the asphalt to be tested; when the radius of complete coverage by the asphalt to be tested is... When the bottom of the circular ingot is reached, ,in, The radius of the bottom end of the circular ingot is... Pi is the mathematical constant of a circle.

[0023] This invention also provides an asphalt-aggregate interface pull-out test apparatus for implementing the above-mentioned asphalt-aggregate interface pull-out test method. The apparatus includes a universal testing machine, an upper loading end, a lower loading end, a pull-out fixture, a calibration component, and a data processing controller. The universal testing machine is provided with an upper loading end and a lower loading end. The pull-out fixture includes an upper limit pressure plate and a lower bearing pressure plate arranged opposite each other, a locking screw, a centering screw, a pull-out force transmission spindle, a washer, a support block, and a nut. The upper limit pressure plate has a pull-out opening for the pull-out force transmission spindle to pass through, and the bottom end of the pull-out force transmission spindle is used for the asphalt-aggregate interface sample to be tested to pass through. The test piece consists of a block; a locking screw connecting the upper limit plate and the lower bearing plate, with the nut located below the lower bearing plate; a centering screw that moves through the lower bearing plate, its top end connected to the support block, and a washer located between the support block and the lower bearing plate; an upper loading end for clamping the pull-out force-transmitting spindle, and a lower loading end for clamping the centering screw; a calibration component that can be installed with the same clamping state and force transmission path as the test piece; and a data processing controller connected to the universal testing machine for acquiring loads and measuring total displacement, and controlling the displacement loading speed and pull-out termination.

[0024] Furthermore, there are four locking screws, which are respectively fixed to the four corners of the upper limit pressure plate and pass through the lower bearing pressure plate. The lower bearing pressure plate moves along the locking screws, and each locking screw is threadedly connected to a nut located below the lower bearing pressure plate. The support block is fixed to the top of the centering screw, and the washer is sleeved on the centering screw and located between the support block and the lower bearing pressure plate, so that when the nut is tightened, the lower bearing pressure plate pushes the support block through the washer to clamp the substrate test block between the support block and the upper limit pressure plate.

[0025] Furthermore, the calibration component includes an upper clamping section and a calibration bearing section connected to each other. The upper clamping section is used to be clamped by the upper loading end, and the calibration bearing section is used to be clamped between the upper limit pressure plate and the support block. The axial stiffness of the calibration component is known. The data processing controller includes a processor, a memory, a data acquisition interface, and a loading control interface. The data acquisition interface is used to receive the load and measured total displacement output by the universal testing machine. The loading control interface is used to output displacement loading speed adjustment commands and pull-out termination commands to the universal testing machine. Attached Figure Description

[0026] Figure 1 This is a schematic flowchart of a pull-out test method for the asphalt-aggregate interface according to an embodiment of the present invention; Figure 2 This is a load-corrected pull-out displacement curve of the composite modified asphalt mortar specimen with a 20% lime replacement rate in the experimental example of this invention. Figure 3 This is a three-dimensional structural schematic diagram of an asphalt-aggregate interface pull-out test device according to an embodiment of the present invention; Figure 4 This is a front view schematic diagram of a pull-out test device for the asphalt-aggregate interface according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Upper limit pressure plate; 2. Lower bearing pressure plate; 3. Matrix test block; 4. Pull-out port; 5. Locking screw; 6. Centering screw; 7. Pull-out force transmission spindle; 8. Washer; 9. Support block; 10. Nut. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0029] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0031] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0032] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0033] See Figure 1 An embodiment of the present invention provides a pull-out test method for the asphalt-aggregate interface, comprising the following steps: S1, with axial stiffness as The calibration components were installed according to the force transmission path of the formal pull-out, and the total displacement was measured and calibrated by applying loads in stages. ,according to

[0034] Establish system deformation curves; S2. The pull-out force transmission spindle 7 is connected to the substrate test block 3 through the asphalt to be tested. The substrate test block 3 is clamped by the upper limit pressure plate 1 and the support block 9. The upper loading end of the universal testing machine clamps the pull-out force transmission spindle 7, and the lower loading end clamps the centering screw 6. S3. Pulling out using displacement control, collecting the data. Load at each sampling point and measuring total displacement ,according to

[0035] Obtain the corrected pull-out displacement; S4. Calculate the real-time stiffness from the load and the corrected pull-out displacement, determine the reference stiffness with the initial loading segment stiffness, and reduce the displacement loading speed when the real-time stiffness continuously decreases relative to the reference stiffness to a preset level. S5. When the ratio of load to peak load is not greater than the preset ratio and the state in which the incremental correction work in the preset sampling window is not greater than the preset threshold for a preset number of consecutive times, the pull-out is terminated. The interface bond strength and the correction adhesion work are calculated based on the maximum load, the effective coverage area of ​​the asphalt to be tested and the load-correction pull-out displacement data. in, The sampling point number, To calibrate the axial stiffness of the component, For the calibration component itself in Axial deformation under load, For load The total displacement under calibration, For system deformation, To measure the total displacement, For the first Load at each sampling point To correct the pull-out displacement.

[0036] In this embodiment, addressing the issues of measuring total displacement in pull-out experiments including system deformation, the difficulty in balancing efficiency and data density at critical stages due to constant loading speed, and the reliance on subjective judgment for experiment termination, this experimental method first checks the universal testing machine, upper loading end, lower loading end, and pull-out fixture before the experiment to ensure proper fit of locking screw 5, nut 10, centering screw 6, support block 9, and washer 8. A calibration component with known axial stiffness is installed at the same force transmission position as the actual test specimen. A predetermined load level is applied incrementally, and the load and calibration total displacement are recorded. The processor subtracts the deformation of the calibration component itself from the calibration total displacement, generating a curve corresponding to the load and system deformation. After calibration, the calibration component is removed. The pull-out force transmission spindle 7 is connected to the substrate specimen 3 via the asphalt to be tested. The substrate specimen 3 is clamped between the upper limit pressure plate 1 and the support block 9. The upper and lower loading ends respectively clamp the pull-out force transmission spindle 7 and the centering screw 6. After zeroing, displacement control pull-out is initiated. The data processing controller acquires the load and measures the total displacement point by point, queries the system deformation curve, and calculates the corrected pull-out displacement. During loading, stiffness is calculated in real time, and the speed and sampling frequency are adjusted according to the continuous decrease in stiffness. After the peak, the peak load, cumulative corrected work, and the incremental corrected work within the window are calculated synchronously. The process only stops when the load decay and energy convergence conditions are continuously met. Finally, the interface bond strength is calculated from the maximum load and the effective coverage area, and the corrected adhesive work is obtained by integrating the load-corrected pull-out displacement curve. Among these, the calibration part is subjected to graded loading under the same clamping state and force transmission path as the formal pull-out, and the axial deformation of the calibration part itself is deducted to obtain the comprehensive deformation of the experimental system as the load changes. In the formal experiment, the system deformation is deducted from the measured total displacement, which helps to make the displacements involved in the stiffness and adhesive work calculations closer to the actual relative displacement of the interface under test. Furthermore, the real-time stiffness is calculated using the load-displacement data after system flexibility correction, and the loading speed is reduced and the sampling frequency is increased when the real-time stiffness continuously decreases relative to the initial reference stiffness, which can maintain experimental efficiency in the initial stage. Increasing data density near the peak and during the post-peak softening phase reduces erroneous adjustments caused by single-point fluctuations. Simultaneously, combining the attenuation of the current load relative to the operating peak load with the convergence of the cumulative corrected work within the sampling window, and requiring termination of pull-out only after both conditions are continuously met, transforms the subjective condition of "complete interface failure" into a calculable and verifiable objective termination condition. This facilitates the complete preservation of effective post-peak curves and unifies the termination criteria for different experiments. Calculating interface bond strength, corrected adhesion work, and corrected adhesion work per unit effective coverage area on the same data chain allows each index to be traced back to the original load, total displacement, system deformation, and control state, thereby significantly improving the comparability and traceability of experimental results.

[0037] Optionally, in step S2, the substrate test block 3 is placed centered on the support block 9. The upper limit pressure plate 1 is provided with a pull-out port 4. The upper limit pressure plate 1 and the lower bearing pressure plate 2 are connected by multiple locking screws 5. A nut 10 is provided below the lower bearing pressure plate 2 and is threadedly connected to the locking screws 5. A washer 8 is provided between the support block 9 and the lower bearing pressure plate 2 so that the pull-out force transmission spindle 7 passes through the pull-out port 4. The nuts 10 located below the lower bearing pressure plate 2 are tightened sequentially in a diagonal alternating order. Each nut 10 causes the lower bearing pressure plate 2 to move along each locking screw 5 toward the upper pressure plate 1 and compress the gasket 8 until the substrate test block 3 is clamped; the upper loading end and the lower loading end respectively clamp the pull-out force transmission spindle 7 and the centering screw 6, adjust the installation position so that the axis of the pull-out force transmission spindle 7, the center of the effective coverage area of ​​the asphalt to be tested, the center of the substrate test block 3 and the axis of the centering screw 6 are in the same vertical loading axis, and after the load and displacement are cleared to zero, proceed to step S3.

[0038] In this embodiment, during clamping, the center of the substrate test block 3 is first aligned with the center of the support block 9, so that the pull-out force transmission spindle 7 connected to the upper surface of the substrate test block 3 passes through the pull-out port 4 at the center of the upper limit pressure plate 1. Each nut 10 is engaged with the corresponding locking screw 5 from below the lower bearing pressure plate 2. The operator tightens them in a diagonal sequence, keeping the adjustment amount similar each time, so that the lower bearing pressure plate 2 moves upward smoothly. The lower bearing pressure plate 2 transmits force to the support block 9 through the shim 8. The support block 9 supports the substrate test block 3 and presses it against the upper limit pressure plate 1; the shim 8 is gradually compressed to avoid the clamping force suddenly acting on a local part of the test block. After the clamping is stable, the upper part of the pull-out force transmission spindle 7 is clamped by the upper loading end, and the lower part of the centering screw 6 is clamped by the lower loading end. The position of the clamp relative to the loading position is adjusted so that the axis of the pull-out force transmission spindle 7, the center of the effective asphalt coverage area, the center of the substrate test block 3, and the axis of the centering screw 6 are on the same vertical loading axis. After confirming that the drawing force transmission spindle 7 has a movement gap within the drawing port 4, the load channel and displacement channel are then zeroed. This operation reduces the tilt of the pressure plate by alternating diagonal tightening and reduces the additional bending moment by using a coaxial force transmission path, which helps to make the interface stress more uniform and improves the consistency of repeated clamping.

[0039] Optionally, in step S1, the calibration component is subjected to graded loading using the same nut 10 tightening sequence, clamping position, zeroing method, and loading range as the actual pull-out; the calibration component itself is under load The axial deformation below is ,and For loads between adjacent calibration load points, interpolation is performed using the experimental system deformation corresponding to the adjacent calibration load points to obtain the load corresponding to the specified value. .

[0040] In this embodiment, the calibration component has a known and stable axial stiffness. Its calibration load-bearing section is placed between the support block 9 and the upper limit pressure plate 1. The upper clamping section is clamped by the upper loading end, and the lower loading end still clamps the centering screw 6. During calibration, the diagonal tightening sequence of the nuts 10, the clamping position of the base test block 3, the load and displacement zeroing method, and the expected load range are used in the formal experiment. The universal testing machine applies the load step by step, and records the total calibration displacement at each load level. The axial deformation of the calibration component itself is equal to the load divided by the axial stiffness of the calibration component. Subtracting this deformation from the total calibration displacement yields the comprehensive deformation of the frame, loading end, clamp, and connection parts under the corresponding load. Interpolation is used to establish a continuously queryable system deformation curve between adjacent calibration load points. During the formal pull-out, the system deformation of each sampling point is obtained according to the current load and subtracted from the measured total displacement. The principle is to make the calibration process share the same force transmission boundary with the formal process, and replace the interface to be measured with only the calibration part with known stiffness. Therefore, the system deformation can be separated from the total displacement. This correction is beneficial to improving the physical relevance of stiffness change judgment and adhesion work integral.

[0041] Optionally, in step S5, according to

[0042] Calculate the corrected adhesion work, and according to

[0043] Calculate the adhesive work corrected for the effective coverage area per unit; in, To correct the adhesion work, This represents the total number of sampling points during the pulling process. and The first The and the first Load at each sampling point and The first The and the first Corrected pull-out displacement at each sampling point The effective coverage area of ​​the asphalt to be tested. The adhesive work is corrected per unit effective coverage area, and the load and corrected pull-out displacement are calculated according to the sampling time sequence.

[0044] In this embodiment, after the formal pull-out is completed, the original time sequence of each sampling point is retained, and the load, total measured displacement, corresponding system deformation, and corrected pull-out displacement are associated and saved. When calculating the corrected adhesion work, for any adjacent sampling point, the arithmetic mean of the loads at the two points is first taken, and then multiplied by the difference in the corrected pull-out displacements at the two points to obtain the trapezoidal area corresponding to that interval; the area is accumulated from the first sampling interval to the final sampling point to obtain the total area under the corrected load-displacement curve. If there are occasional repetition points in the displacement channel, the original time sequence can be retained and the zero displacement increment interval can be recorded as zero area, without changing the direction of the curve after the peak by reordering. The corrected adhesion work is further divided by the effective coverage area of ​​the asphalt to be tested to obtain the corrected adhesion work per unit effective coverage area, which is used to compare the results of different spindle bottom areas. The working principle of this calculation is to perform trapezoidal integration on the discrete curve after the system compliance correction, so that the energy stored in the fixture and loading system is no longer directly included in the interface energy consumption; the unit area normalization reduces the influence of specimen size differences on energy indicators, which is beneficial to evaluate the interface performance from the perspectives of load-bearing capacity and energy consumption.

[0045] Optionally, in step S4, according to

[0046] Calculate the first Real-time stiffness of each stiffness determination window and based on the real-time stiffness of each segment within the initial loading phase. The median is used as the reference stiffness. ; when The state appears continuously When applying a stiffness determination window, the displacement loading speed is changed from... Down to And the sampling frequency was changed from Increase to ;in, The number of sampling intervals included in the stiffness determination window and , The stiffness reduction threshold is greater than 0 and less than 1. To preset the number of consecutive windows, and The displacement loading speeds before and after adjustment are respectively. , and The sampling frequencies before and after adjustment are respectively. .

[0047] In this embodiment, during the initial stage of formal pull-out, a first displacement loading speed and a first sampling frequency are used. The data processing controller calculates the ratio of the current load increment to the corrected pull-out displacement increment according to a fixed sampling interval window, which is used as the real-time stiffness. Multiple real-time stiffness values ​​can be obtained within the initial near-linear loading segment. The processor takes the median as the reference stiffness to reduce the impact of noise at a single sampling point on the benchmark. Subsequently, the ratio of real-time stiffness to reference stiffness is continuously calculated. Only when this ratio is not greater than the stiffness reduction threshold for a preset number of consecutive windows does the loading control interface send an adjustment command to the universal testing machine to reduce the speed to the second displacement loading speed. And increase the sampling frequency to the second sampling frequency. For windows with displacement differences not greater than zero, they are not included in real-time stiffness determination to avoid denominator anomalies. When the interface transitions from elastic or near-linear response to the damage and softening stage, the rate of increase of load relative displacement decreases, thus real-time stiffness can serve as a feedback quantity near the peak and post-peak stages. Continuous window determination suppresses occasional noise, while speed reduction and frequency enhancement are beneficial for obtaining denser curve data in critical stages.

[0048] Optionally, in step S5, according to

[0049] Determine as of the date Peak operating load at each sampling point ,according to

[0050] Determine as of the date The cumulative correction power of each sampling point and in According to

[0051] Determine the increment of the correction work; when and The state appears continuously The pulling process was terminated at each sampling point. in, The sampling point number in the cumulative summation. The number of sampling intervals included in the preset sampling window. The load proportion threshold is greater than 0 and less than 1. The energy threshold is greater than 0 and less than 1. To prevent the default positive number with a denominator of zero, To preset the number of consecutive sampling points, This is the function for finding the maximum value.

[0052] In this embodiment, after loading begins, the processor updates the maximum load that has occurred up to the current moment at each sampling point, using it as the operating peak load, and does not use the final data that can only be determined after the experiment to control the real-time process. Simultaneously, the processor accumulates the product of the average value of adjacent loads and the correction displacement increment according to the sampling sequence to obtain the current cumulative correction work. When the number of sampling points exceeds the preset window length, the absolute value of the difference between the current cumulative correction work and the cumulative correction work at the beginning of the window represents the correction work increment within the window. After entering the post-peak stage, the processor determines whether the ratio of the current load to the operating peak load is not greater than the load ratio threshold, and whether the correction work increment relative to the cumulative correction work is not greater than the energy threshold. Both conditions must be met simultaneously at consecutive preset sampling points before the loading control interface outputs a stop command. The load ratio indicates that the interface's bearing capacity has significantly decreased, and the energy condition indicates that the additional energy consumption generated by continued loading tends to be small; the combination of these two conditions can eliminate false stops caused by instantaneous load reduction or single-point noise, and transform the originally observation-dependent endpoint into an objective criterion that can be recorded and verified.

[0053] Optionally, in step S5, according to

[0054] Calculate the interfacial bond strength; in, For interfacial bond strength, This represents the maximum load during the pull-out process. The effective coverage area formed between the bottom end of the pull-out force transmission spindle 7 and the asphalt to be tested; when the radius of complete coverage by the asphalt to be tested is When the bottom of the circular ingot is reached, ,in, The radius of the bottom end of the circular ingot is... Pi is the mathematical constant of a circle.

[0055] In this embodiment, to evaluate the water damage resistance of the asphalt-aggregate interface, multiple parallel specimens were prepared using the same batch of matrix blocks 3, asphalt to be tested, and pull-out force-transmitting spindles 7. These parallel specimens were divided into a dry reference group and a water-immersed group. The material composition, sample preparation method, effective coverage area, molding conditions, experimental temperature, clamping method, and loading parameters were kept consistent between the two groups. The dry reference group specimens were dried and cured for 1 day after molding, while the water-immersed group specimens were immersed in water at a preset temperature for t days after molding. After immersion, the specimens were removed, surface water was removed, and clamping and pull-out tests were completed within a preset time.

[0056] Because the pull-out test causes irreversible damage to the interface under test, the dry reference group and the immersion group used independent parallel specimens. All specimens in each group were tested using the same system compliance calibration method, displacement correction method, adaptive loading method, and objective termination condition. If the fixture was disassembled, the gasket 8 was replaced, or the tightness of the nut 10 changed between the two groups of experiments, system compliance calibration was performed separately to reduce the impact of fixture changes on the experimental results. After the experiment, the interfacial bond strength of each parallel specimen in the dry reference group and the immersion group was calculated, and the residual bond strength ratio was calculated based on the average interfacial bond strength of each group of parallel specimens.

[0057] In the formula, R The percentage of residual bond strength after immersion in water for t days is expressed as % . P 0 represents the average interfacial bond strength of parallel specimens after 1 day of drying and curing, in MPa. P t The average interfacial bond strength of parallel specimens after immersion in water for t days is expressed in MPa; t is the preset number of immersion days.

[0058] The residual bond strength ratio is used to characterize the degree of strength retention of the asphalt-aggregate interface after immersion in water. Under the same material composition and experimental conditions, a higher residual bond strength ratio indicates a higher bond strength retained at the interface after immersion in water. By applying systematic compliance calibration, real-time stiffness adaptive loading, and objective termination conditions to both sets of specimens, the influence of fixture deformation, loading process, and termination point differences on the results of the two sets can be reduced, thereby improving the comparability and traceability of the residual bond strength ratio.

[0059] See Figure 3 and Figure 4This invention also provides an asphalt-aggregate interface pull-out test apparatus for implementing the above-mentioned asphalt-aggregate interface pull-out test method. The apparatus includes a universal testing machine, an upper loading end, a lower loading end, a pull-out fixture, a calibration component, and a data processing controller. The universal testing machine is provided with an upper loading end and a lower loading end. The pull-out fixture includes an upper limit pressure plate 1 and a lower bearing pressure plate 2 arranged opposite to each other, a locking screw 5, a centering screw 6, a pull-out force transmission spindle 7, a gasket 8, a support block 9, and a nut 10. The upper limit pressure plate 1 has a pull-out opening 4 for the pull-out force transmission spindle 7 to pass through, and the bottom end of the pull-out force transmission spindle 7 is used to connect the substrate through the asphalt to be tested. Test block 3; the locking screw 5 connects the upper limit pressure plate 1 and the lower bearing pressure plate 2, and the nut 10 is located below the lower bearing pressure plate 2; the centering screw 6 moves through the lower bearing pressure plate 2, and its top end is connected to the support block 9; the washer 8 is located between the support block 9 and the lower bearing pressure plate 2; the upper loading end is used to clamp the pull-out force transmission spindle 7, and the lower loading end is used to clamp the centering screw 6; the calibration component can be installed in the same clamping state and force transmission path as the test piece; the data processing controller is connected to the universal testing machine and is used to collect loads and measure total displacement, and control the displacement loading speed and pull-out termination.

[0060] In this embodiment, the experimental apparatus consists of a universal testing machine, an upper loading end, a lower loading end, a pull-out clamp, a calibration component, and a data processing controller. The upper limit plate 1 of the pull-out clamp is positioned opposite to the lower bearing plate 2. A locking screw 5 limits the relative movement path of the two plates, and a nut 10 located below the lower bearing plate 2 pushes the lower bearing plate 2 upwards. A centering screw 6 moves through the lower bearing plate 2, its upper end connected to a support block 9, which supports the substrate specimen 3. A gasket 8 is positioned between the support block 9 and the lower bearing plate 2. The pull-out force transmission spindle 7 extends from the pull-out port 4 of the upper limit plate 1, its bottom end connected to the substrate specimen 3 via the asphalt to be tested, and its upper end clamped by the upper loading end; the lower end of the centering screw 6 is clamped by the lower loading end. This forms a vertical force transmission chain where the upper loading end, pull-out force transmission spindle 7, the asphalt to be tested, the substrate specimen 3, the support block 9, the centering screw 6, and the lower loading end are sequentially subjected to force. The calibration component can replace the test piece and be installed at the same force transmission position. The data processing controller is connected to the universal testing machine and undertakes the functions of data acquisition and control. This overall structure allows the formal pull-out and calibration to share the same mechanical boundary, providing a unified hardware foundation for system compliance correction, adaptive loading, and objective termination.

[0061] Optionally, there are four locking screws 5, which are respectively fixed to the four corners of the upper limit pressure plate 1 and pass through the lower bearing pressure plate 2. The lower bearing pressure plate 2 moves along the locking screws 5, and each locking screw 5 is threadedly connected to a nut 10 located below the lower bearing pressure plate 2. The support block 9 is fixed to the top of the centering screw 6, and the washer 8 is sleeved on the centering screw 6 and located between the support block 9 and the lower bearing pressure plate 2, so that when the nut 10 is tightened, the lower bearing pressure plate 2 pushes the support block 9 through the washer 8 to clamp the substrate test block 3 between the support block 9 and the upper limit pressure plate 1.

[0062] In this embodiment, the upper limit plate 1 and the lower bearing plate 2 can be made into parallel square metal plates. Four locking screws 5 are fixed at the four corners of the upper limit plate 1 and pass downward through the lower bearing plate 2. The four screws are symmetrically arranged around the base specimen 3. Nuts 10 are threadedly engaged with each locking screw 5 and are located below the lower bearing plate 2. The centering screw 6 passes through the middle of the lower bearing plate 2, and its top end is fixed to the support block 9. The washer 8 is sleeved on the outside of the centering screw 6. When the nut 10 is tightened, the lower bearing plate 2 moves upward along the four locking screws 5, and pushes the support block 9 through the washer 8, so that the base specimen 3 is clamped between the support block 9 and the upper limit plate 1. The washer 8 can be a metal washer 8 or a combination washer 8 with pressure buffering capacity and meeting the loading stiffness requirements. The pull-out force transmission spindle 7 can be made of stainless steel. The upper and lower plates, locking screws 5 and nuts 10 can be made of metal materials with sufficient stiffness. In the specific experiment, the substrate specimen 3 was a 50mm×50mm×50mm granite cube. The four-point symmetrical constraint made the movement of the lower bearing plate 2 more stable. The cooperation between the support block 9 and the shim 8 could mitigate the increase of clamping force and reduce the risk of local damage to the specimen, while retaining the convenience of disassembly, adjustment and reuse.

[0063] Optionally, the calibration component includes an upper clamping section and a calibration bearing section connected to each other. The upper clamping section is used to be clamped by the upper loading end, and the calibration bearing section is used to be clamped between the upper limit pressure plate 1 and the support block 9. The axial stiffness of the calibration component is known. The data processing controller includes a processor, a memory, a data acquisition interface, and a loading control interface. The data acquisition interface is used to receive the load and measured total displacement output by the universal testing machine. The loading control interface is used to output displacement loading speed adjustment commands and pull-out termination commands to the universal testing machine.

[0064] In this embodiment, the calibration component consists of an upper clamping section and a calibration bearing section connected to each other. The shape of the upper clamping section matches the clamping method of the upper loading end, and the shape and force-bearing position of the calibration bearing section enable it to be stably clamped between the upper limit pressure plate 1 and the support block 9. The calibration component maintains axial force within a predetermined load range, and its axial stiffness is obtained through manufacturing parameters, individual calibration or verification, and written into the memory. The data processing controller includes a processor, a memory, a data acquisition interface, and a loading control interface. The data acquisition interface receives the load and measured total displacement output by the universal testing machine. The processor performs system deformation interpolation, displacement correction, real-time stiffness, peak operating load, cumulative correction work, and final performance parameter calculations. The memory stores calibration curves, control thresholds, original sampling data, and command status. The loading control interface sends speed adjustment and stop commands to the universal testing machine. This controller can be implemented by an industrial computer, testing machine control host, or programmable control unit with data acquisition and command output capabilities. Its working principle is to associate the deformation reference obtained by mechanical calibration with the real-time data of the formal experiment, and form a closed-loop chain of "acquisition-calculation-judgment-control-recording", so that every speed change and termination decision can be traced.

[0065] Experimental Example: Interfacial Pull-out Test of Composite Modified Asphalt Mortar with 20% Lime Replacement Rate In this experimental example, a composite modified asphalt mortar with a slaked lime replacement rate of 20% was used as the test material, and a 50mm×50mm×50mm granite cube was used as the matrix specimen 3. The pull-out force transmission spindle 7 was made of stainless steel, with a circular plane at its bottom with a radius of 10.00mm. The composite modified asphalt mortar was prepared according to the original formula and sample preparation process, and placed between the bottom end of the pull-out force transmission spindle 7 and the upper surface of the matrix specimen 3, so that the composite modified asphalt mortar completely covered the bottom end of the pull-out force transmission spindle 7 to form the asphalt-aggregate interface to be tested.

[0066] The prepared test specimen was immersed in 20℃ water for 3 days. After immersion, the test specimen was removed, and the surface water was removed. The substrate block 3 was placed centered on the support block 9 of the drawing fixture, so that the drawing force transmission spindle 7 passed through the drawing port 4 of the upper limit pressure plate 1. The nuts 10 were tightened alternately diagonally, so that the lower bearing pressure plate 2 moved towards the upper limit pressure plate 1 along the locking screw 5, and the support block 9 was pushed by the shim 8 to clamp the substrate block 3. The upper loading end of the universal testing machine clamped the top of the drawing force transmission spindle 7, and the lower loading end clamped the bottom of the centering screw 6. The position of the fixture was adjusted so that the drawing force transmission spindle 7, the test interface, the substrate block 3 and the centering screw 6 were on the same vertical loading axis.

[0067] Before the formal pull-out test, a calibration piece with known axial stiffness was used to apply graded loads under the same clamping condition and force transmission path as the test specimen, establishing the correspondence between load and experimental system deformation. After completing the system flexibility calibration, the calibration piece was removed and the test specimen was installed, and the load and displacement were zeroed. The universal testing machine was used to pull out the test specimen vertically, simultaneously collecting load and displacement data. The corrected pull-out displacement was calculated based on the system deformation curve of the calibration piece. The load-corrected pull-out displacement curve of the 20% lime replacement rate composite modified asphalt mortar after immersion in water at 20℃ for 3 days is shown below. Figure 2 As shown.

[0068] The peak load of the curve is approximately 1014.7 N, corresponding to a displacement of approximately 0.95 mm. The effective coverage area formed between the bottom end of the pull-out force transmission spindle 7 and the asphalt to be tested is calculated according to the following formula:

[0069] In the formula, The effective coverage area of ​​the asphalt to be tested is expressed in mm². The radius of the circular bottom end of the drawing force transmission spindle 7 is in mm; Pi is the mathematical constant of a circle.

[0070] The bottom radius of the pull-through force transmission spindle 7 Substituting mm into the above formula, we get:

[0071] Interfacial bond strength is calculated using the following formula:

[0072] Substituting the peak load and effective coverage area of ​​this experiment into the above formula, the interfacial bond strength after immersion in water at 20℃ for 3 days is obtained:

[0073] In the formula, Immerse the specimen in water The interfacial bond strength after the experiment; in this experimental example Therefore, the interfacial bond strength after immersion in water for 3 days is approximately 3.23 MPa.

[0074] by Figure 2 Based on the horizontal and vertical coordinate scales, several representative data points were read, and the reading results are shown in Table 1.

[0075] Table 1. Representative load-corrected pull-out displacement data and adhesion work integral verification results

[0076] The adhesive work was calculated using the trapezoidal integral method based on the discrete load-corrected pull-out displacement data.

[0077] In the formula, The adhesive work is the work performed within the recorded range of the load-corrected pull-out displacement curve, in N·mm. This represents the total number of sampling points; The sampling point number; and The first The and the first The load at each sampling point is expressed in N. and These represent the corrected pull-out displacements for the corresponding sampling points, in mm.

[0078] right Figure 2 Integrating all the digitized data points, the adhesion work within the recording range is approximately:

[0079] Table 1 lists only some representative check points; the result for 544.1 N·mm is from... Figure 2 The results are obtained by integrating all the digital points, not simply by adding up the areas of the trapezoids corresponding to the check points listed in Table 1.

[0080] This experimental example demonstrates that the pull-out fixture can vertically pull the composite modified asphalt mortar-granite interface after water immersion treatment, and obtain a load-corrected pull-out displacement curve including the rising segment, peak value, and post-peak attenuation segment. Based on this curve, the peak load and interfacial bond strength can be determined, and the adhesion work can be calculated through curve integration.

[0081] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A pull-out test method for asphalt-aggregate interface, characterized in that, Includes the following steps: S1, with axial stiffness as The calibration components were installed according to the force transmission path of the formal pull-out, and the total displacement was measured and calibrated by applying loads in stages. ,according to Establish system deformation curves; S2. The pull-out force transmission spindle (7) is passed through the asphalt-connected matrix test block (3) to be tested. The matrix test block (3) is clamped by the upper limit pressure plate (1) and the support block (9). The upper loading end of the universal testing machine clamps the pull-out force transmission spindle (7), and the lower loading end clamps the centering screw (6). S3. Pulling out using displacement control, collecting the data. Load at each sampling point and measuring total displacement ,according to Obtain the corrected pull-out displacement; S4. Calculate the real-time stiffness from the load and the corrected pull-out displacement, determine the reference stiffness with the initial loading segment stiffness, and reduce the displacement loading speed when the real-time stiffness continuously decreases relative to the reference stiffness to a preset level. S5. When the ratio of load to peak load is not greater than the preset ratio and the state in which the incremental correction work in the preset sampling window is not greater than the preset threshold for a preset number of consecutive times, the pull-out is terminated. The interface bond strength and the correction adhesion work are calculated based on the maximum load, the effective coverage area of ​​the asphalt to be tested and the load-correction pull-out displacement data. in, The sampling point number, To calibrate the axial stiffness of the component, For the calibration component itself in Axial deformation under load, For load The total displacement under calibration, For system deformation, To measure the total displacement, For the first Load at each sampling point To correct the pull-out displacement.

2. The asphalt-aggregate interface pull-out test method according to claim 1, characterized in that, In step S2, the substrate test block (3) is placed centered on the support block (9). The upper limit pressure plate (1) is provided with a pull-out port (4). The upper limit pressure plate (1) and the lower bearing pressure plate (2) are connected by multiple locking screws (5). A nut (10) threadedly connected to the locking screw (5) is provided below the lower bearing pressure plate (2). A washer (8) is provided between the support block (9) and the lower bearing pressure plate (2). The pull-out force transmission spindle (7) passes through the pull-out port (4). The lower bearing pressure plate (2) is tightened sequentially in a diagonal alternating order. The nuts (10) below cause the lower bearing pressure plate (2) to move along the locking screws (5) toward the upper pressure plate (1) and compress the gasket (8) until the substrate test block (3) is clamped; the upper loading end and the lower loading end clamp the pull-out force transmission spindle (7) and the centering screw (6) respectively, adjust the installation position so that the axis of the pull-out force transmission spindle (7), the center of the effective coverage area of ​​the asphalt to be tested, the center of the substrate test block (3) and the axis of the centering screw (6) are in the same vertical loading axis. After the load and displacement are cleared, step S3 is executed.

3. The asphalt-aggregate interface pull-out test method according to claim 2, characterized in that, In step S1, the calibration component is subjected to graded loading using the same nut (10) tightening sequence, clamping position, zeroing method, and loading range as the formal pull-out; the calibration component itself is under load The axial deformation below is ,and For loads between adjacent calibration load points, interpolation is performed using the deformation of the experimental system corresponding to the adjacent calibration load points to obtain the load corresponding to the specified value. .

4. The asphalt-aggregate interface pull-out test method according to claim 1, characterized in that, In step S5, according to Calculate the corrected adhesion work, and according to Calculate the adhesive work corrected for the effective coverage area per unit; in, To correct the adhesion work, This represents the total number of sampling points during the pulling process. and The first The and the first Load at each sampling point and The first The and the first Corrected pull-out displacement at each sampling point The effective coverage area of ​​the asphalt to be tested. The adhesive work is corrected per unit effective coverage area, and the load and corrected pull-out displacement are calculated according to the sampling time sequence.

5. The asphalt-aggregate interface pull-out test method according to claim 1, characterized in that, In step S4, according to Calculate the first Real-time stiffness of each stiffness determination window and based on the real-time stiffness of each segment within the initial loading phase. The median is used as the reference stiffness. ; when The state appears continuously When applying a stiffness determination window, the displacement loading speed is changed from... Down to And the sampling frequency was changed from Increase to ;in, The number of sampling intervals included in the stiffness determination window and , The stiffness reduction threshold is greater than 0 and less than 1. To preset the number of consecutive windows, and The displacement loading speeds before and after adjustment are respectively. , and The sampling frequencies before and after adjustment are respectively. .

6. The asphalt-aggregate interface pull-out test method according to claim 1, characterized in that, In step S5, according to Determine as of the date Peak operating load at each sampling point ,according to Determine as of the date The cumulative correction power of each sampling point and in According to Determine the increment of the correction work; when and The state appears continuously The pulling process was terminated at each sampling point. in, The sampling point number in the cumulative summation. The number of sampling intervals included in the preset sampling window. The load proportion threshold is greater than 0 and less than 1. The energy threshold is greater than 0 and less than 1. To prevent the default positive number with a denominator of zero, To preset the number of consecutive sampling points, This is the function for finding the maximum value.

7. The asphalt-aggregate interface pull-out test method according to claim 1, characterized in that, In step S5, according to Calculate the interfacial bond strength; in, For interfacial bond strength, This represents the maximum load during the pull-out process. The effective coverage area formed between the bottom end of the pull-out force transmission spindle (7) and the asphalt to be tested; when the radius of complete coverage of the asphalt to be tested is When the bottom of the circular ingot is reached, ,in, The radius of the bottom end of the circular ingot is... Pi is the mathematical constant of a circle.

8. A pull-out test apparatus for the asphalt-aggregate interface, used to perform the pull-out test method for the asphalt-aggregate interface as described in any one of claims 1-7, characterized in that, The system includes a universal testing machine, a pull-out fixture, calibration components, and a data processing controller. The universal testing machine is equipped with an upper loading end and a lower loading end. The pull-out fixture includes an upper limit pressure plate (1) and a lower bearing pressure plate (2) arranged opposite to each other, a locking screw (5), a centering screw (6), a pull-out force transmission spindle (7), a washer (8), a support block (9), and a nut (10). The upper limit pressure plate (1) is provided with a pull-out opening (4) for the pull-out force transmission spindle (7) to pass through, and the bottom end of the pull-out force transmission spindle (7) is used to connect the substrate test block (3) through the asphalt to be tested. The locking screw (5) connects the upper limit pressure plate (1) and the lower bearing pressure plate (2). The load plate (2) has a nut (10) located below the lower load plate (2); the centering screw (6) moves through the lower load plate (2), and its top end is connected to the support block (9); the gasket (8) is located between the support block (9) and the lower load plate (2); the upper loading end is used to clamp the pull-out force transmission spindle (7), and the lower loading end is used to clamp the centering screw (6); the calibration component can be installed in the same clamping state and force transmission path as the test piece; the data processing controller is connected to the universal testing machine and is used to collect the load and measure the total displacement, and control the displacement loading speed and pull-out termination.

9. The asphalt-aggregate interface pull-out test apparatus according to claim 8, characterized in that, The locking screws (5) are four in number, which are fixed at the four corners of the upper limit pressure plate (1) and pass through the lower bearing pressure plate (2). The lower bearing pressure plate (2) moves along the locking screws (5). Each locking screw (5) is threadedly connected to the nut (10) located below the lower bearing pressure plate (2). The support block (9) is fixed at the top of the centering screw (6). The washer (8) is sleeved on the centering screw (6) and located between the support block (9) and the lower bearing pressure plate (2). When the nut (10) is tightened, the lower bearing pressure plate (2) pushes the support block (9) through the washer (8) to clamp the substrate test block (3) between the support block (9) and the upper limit pressure plate (1).

10. The asphalt-aggregate interface pull-out test apparatus according to claim 8, characterized in that, The calibration component includes an upper clamping section and a calibration bearing section connected to each other. The upper clamping section is used to be clamped by the upper loading end, and the calibration bearing section is used to be clamped between the upper limit pressure plate (1) and the support block (9). The axial stiffness of the calibration component is known. The data processing controller includes a processor, a memory, a data acquisition interface and a loading control interface. The data acquisition interface is used to receive the load and measure the total displacement output by the universal testing machine. The loading control interface is used to output displacement loading speed adjustment command and pull-out termination command to the universal testing machine.

Images