A method of asphalt-aggregate interface adhesion scratch testing

Abstract

The present application belongs to the technical field of material testing, and discloses a kind of asphalt-aggregate interface adhesion scratch test method, first cutting aggregate rock block and polishing smooth its surface to be measured;Two blocks of ultra-thin gaskets are pasted respectively on the two sides of the surface to be measured, and the remaining part is coated with the asphalt to be measured, and the ultra-thin gasket is pasted tightly to scrape the asphalt to be measured flat, and the asphalt-aggregate adhesion sample is obtained after sufficient soaking;The asphalt-aggregate adhesion sample is pasted on the test bench with glue to carry out scratch test;The vertical pressure, lateral force, penetration depth, first stage indenter sliding distance L1 and second stage indenter sliding distance of the pressure head are recorded;Finally, the asphalt-aggregate interface adhesion is calculated by formula.The present application calculates the adhesion of asphalt film when it is peeled off from asphalt surface by energy principle, which is consistent with the asphalt film peeling process in the process of asphalt concrete water damage, and the interface adhesion measured can be directly used in the calculation and design of asphalt concrete resistance to pore water pressure and interface peeling.

Description

Technical Field

[0001] This invention belongs to the field of materials testing technology, specifically, it relates to a method for testing the adhesion and scratch resistance of asphalt-aggregate interface. Background Technology

[0002] Asphalt concrete roads constitute a large proportion of transportation infrastructure construction. However, due to insufficient technical experience in design, construction, and use, many asphalt roads develop cracks, subsidence, and potholes after only three or four years of use. Traditionally, the main forms of damage to asphalt roads are considered to be high-temperature rutting, low-temperature cracking, and fatigue failure. Recent research indicates that asphalt's weather resistance, especially its water stability, is also a dominant factor contributing to the damage to asphalt concrete roads in my country. Furthermore, water damage has become one of the major defects affecting asphalt concrete roads worldwide.

[0003] The mechanism of water damage in asphalt roads mainly includes two basic processes: loss of asphalt adhesion and asphalt-aggregate spalling, collectively referred to as the adhesion-sparing process. Among these, the adhesion performance between aggregate and asphalt is the decisive factor in determining its water damage performance; therefore, how to measure the aggregate-asphalt adhesion performance is a crucial issue. Currently, my country typically uses the boiling water method to assess aggregate-asphalt adhesion performance, which only allows for qualitative comparisons and cannot quantitatively measure accurate adhesion force. This prevents the quantitative characterization and design of the water damage performance of asphalt concrete. The American Society for Testing and Materials (ASTM) uses a tensile-shear test to measure asphalt adhesion force, which can quantitatively determine the magnitude of the adhesion force; however, due to the high requirements for specimen preparation, it is difficult to promote its widespread use. Summary of the Invention

[0004] This invention aims to solve the technical problems related to the measurement of the adhesion performance of aggregate-asphalt, and provides a scratch test method for the interfacial adhesion force of asphalt-aggregate, which can obtain the interfacial adhesion force between the two based on nano / micro scratch experiments.

[0005] To solve the above-mentioned technical problems, the present invention is implemented through the following technical solution:

[0006] This invention provides a method for testing the scratch resistance of asphalt-aggregate interface adhesion, comprising the following steps:

[0007] (1) Cut the aggregate rock to be tested into square blocks to obtain aggregate rock blocks; and polish the surface of the aggregate rock blocks to be tested to a smooth finish;

[0008] (2) Two ultra-thin pads are attached to both sides of the surface to be tested of the aggregate rock block, and the thickness of the ultra-thin pads is sub-millimeter or micrometer.

[0009] (3) Apply the asphalt to be tested to the surface of the remaining aggregate rock block after pasting the ultra-thin gasket, and scrape the asphalt to be tested flat with the ultra-thin gasket to obtain an asphalt-aggregate adhesion sample with an asphalt film, and wait for the asphalt film to fully wet the surface of the aggregate rock block to be tested.

[0010] (4) Adhere the fully soaked asphalt-aggregate adhesion sample to the test stand with glue;

[0011] (5) Fix the test stand with the asphalt-aggregate adhesion sample pasted on it onto the nano / micro scratch tester and perform a scratch test;

[0012] The nano / micro scratch test process is divided into two stages: In the first stage, the nano / micro indenter is pressed into the asphalt film and slides, but has not yet contacted the test surface of the aggregate rock block; In the second stage, the nano / micro indenter contacts the test surface of the aggregate rock block and continues to slide, peeling the asphalt film off the test surface of the aggregate rock block.

[0013] Record the vertical pressure F and the lateral force F of the indenter. L 1. Indentation depth h; Record the sliding distance L1 of the first stage indenter and the sliding distance L2 of the second stage indenter;

[0014] (6) Calculate the asphalt-aggregate interfacial adhesion force F according to the following formula. S :

[0015] ;

[0016] Among them, F S : Asphalt-aggregate interfacial adhesion force, unit N; F: Vertical pressure of the indenter, unit N; F L : The lateral force of the indenter, in N; F R : Lateral resistance of the asphalt film to the indenter, in N; h max The maximum penetration depth of the indenter into the asphalt film during the first stage, in mm; h ’ max L1: Maximum indentation depth of the second-stage indenter into the asphalt film, in mm; L2: Sliding distance of the first-stage indenter, in mm; L3: Sliding distance of the second-stage indenter, in mm.

[0017] Preferably, in step (1), the side length of the aggregate rock block is 1.5cm and the height is 0.5~1cm.

[0018] Preferably, in step (1), the process of polishing the surface to be tested is to polish it with 200 grit, 400 grit and 800 grit sandpaper in sequence.

[0019] Preferably, in step (2), the length of each ultrathin pad is the same as the side length of the aggregate rock block, the width is 2~3mm, and the thickness is 1μm~1000μm.

[0020] Preferably, in step (2), the ultra-thin gasket is made of PVC sheet.

[0021] Preferably, in step (3), the process of fully wetting the surface of the aggregate rock block to be tested with the asphalt film is as follows: the asphalt-aggregate adhesion sample is placed in a sealed container with a relative humidity of 50%-70% and left to stand for 4 to 24 hours.

[0022] Preferably, in step (3), the test platform is made of an aluminum block with a diameter of 3cm and a height of 2cm.

[0023] The beneficial effects of this invention are:

[0024] This invention provides a scratch test method for asphalt-aggregate interfacial adhesion. The method provides the preparation process of asphalt-aggregate adhesion samples and, based on microscopic scratch test technology, uses the energy principle to calculate the adhesion force of the asphalt film when it peels off the asphalt surface. This is consistent with the asphalt film peeling process during water damage to asphalt concrete. Therefore, the measured interfacial adhesion force can be directly used in the calculation and design of asphalt concrete's resistance to pore water pressure and interfacial peeling. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the preparation of an asphalt-aggregate adhesion sample in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the adhesion between the asphalt-aggregate adhesion sample and the aluminum block in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram illustrating the principle of measuring the adhesion force between asphalt and aggregate interface using nano-scratches / micro-scratches in an embodiment of the present invention.

[0028] In the above figure: 1-aggregate rock block, 2-asphalt film, 3-ultra-thin gasket, 4-scraper, 5-aluminum block. Detailed Implementation

[0029] The present invention will be further described in detail below through specific embodiments. These embodiments will enable those skilled in the art to have a more comprehensive understanding of the present invention, but will not limit the present invention in any way.

[0030] This embodiment provides a method for testing the scratch resistance of asphalt-aggregate interface adhesion, including the following steps:

[0031] Step 1: Aggregate Preparation

[0032] The aggregate rock to be tested is cut into cubes with sides of 1.5 cm and height of 0.5-1 cm, i.e., aggregate rock block 1; and the surface of aggregate rock block 1 to be tested is polished smooth successively with 200 grit, 400 grit, and 800 grit sandpaper. The surface roughness of the aggregate rock to be tested can be adjusted according to the needs of the experiment, but generally should not be lower than the polishing degree of 400 grit sandpaper.

[0033] Step 2: Attach two ultrathin gaskets 3 to both sides of the surface to be tested on the polished aggregate rock block 1. Each ultrathin gasket 3 is 1.5 cm long, 2-3 mm wide, and 1 μm-1000 μm thick. The thickness of the ultrathin gasket 3 is prepared to be sub-millimeter or micrometer thickness according to the needs of the experiment for nano-scratching or micro-scratching. The ultrathin gasket 3 can be made of ultrathin PVC sheet or other solid materials that can be made into ultrathin thicknesses.

[0034] Step 3: Apply the asphalt to be tested to the remaining aggregate rock block 1 after attaching the ultra-thin gasket 3, and use a scraper 4 to smooth the asphalt to be tested against the ultra-thin gasket 3 to obtain an asphalt film 2 with a sub-millimeter or micrometer thickness. After the asphalt film 2 is applied, the asphalt-aggregate adhesion sample preparation is complete. Place the asphalt-aggregate adhesion sample in a sealed container with a relative humidity of 50%-70% and let it stand for 4-24 hours to allow the asphalt film 2 to fully impregnate the surface of the aggregate rock block 1.

[0035] Step 4: Adhere the fully impregnated asphalt-aggregate adhesion sample to an aluminum block 5 with a diameter of 3 cm and a height of 2 cm using adhesive. Depending on the testing requirements of a nano-scratch analyzer or a micro-scratch analyzer, the asphalt-aggregate adhesion sample can also be adhered to its applicable testing platform.

[0036] Step 5: Fix the aluminum block 5 with the asphalt-aggregate adhesion sample attached, or a suitable test stand, onto the nano / micro scratch tester and perform a scratch test. For example... Figure 3 As shown, the nano / micro scratch test can be divided into two stages. In the first stage, the nano / micro indenter is pressed into the asphalt film 2 and slips, but has not yet contacted the test surface of the aggregate rock block 1. In the second stage, the nano / micro indenter contacts the test surface of the aggregate rock block 1, continues to slip, and peels the asphalt film 2 from the test surface of the aggregate rock block 1. At this time, the work done by the lateral force is converted into an increase in interfacial energy. According to the work-energy theorem and the law of conservation of energy, the interfacial adhesion force is calculated.

[0037] Record the vertical pressure F and the lateral force F of the indenter. L The indentation depth h was recorded, and the sliding distance L1 when the indenter did not contact the test surface of the aggregate rock block 1 in the first stage and the sliding distance L2 after the indenter contacted the test surface of the aggregate rock block 1 in the second stage were recorded.

[0038] In the first stage, the nano / micro indenter is pressed into the asphalt film 2 and slips, but has not yet contacted the test surface of the aggregate rock block 1. The slip distance in this stage is L1, and the maximum indentation depth h is h. max This refers to the thickness of the asphalt film 2. The pressure head exerts both vertical pressure F and lateral force F. L The lateral resistance F of the asphalt film 2 to the pressure head R In the second stage, the nano / micro indenter contacts the test surface of aggregate rock block 1, continues to slide, and peels the asphalt film 2 from the test surface of aggregate rock block 1. The sliding distance in this stage is L2, and the maximum indentation depth h is h. ’ max The interfacial adhesion force between the asphalt film 2 and the aggregate rock block 1 is F. S At this point, the work done by the lateral force is converted into an increase in interfacial energy. Based on the work-energy theorem and the law of conservation of energy, the interfacial adhesion force is calculated.

[0039] Step Six: Organize the test data and calculate the asphalt-aggregate interfacial adhesion force F according to the following formula. S :

[0040] ;

[0041] Where F: vertical pressure of the pressure head, in N; F L : The lateral force of the indenter, in N; F R : Lateral resistance of the asphalt film 2 to the indenter, in N; F S Asphalt-aggregate interfacial adhesion force, in N; h max The maximum penetration depth of the first-stage indenter into the asphalt film 2, in mm; h ’ max L1: Maximum indentation depth of the second-stage indenter into the asphalt film 2, in mm; L2: Sliding distance of the first-stage indenter, in mm; L3: Sliding distance of the second-stage indenter, in mm.

[0042] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many specific modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A method for testing the scratch resistance of asphalt-aggregate interface adhesion, characterized in that, The process includes the following: (1) Cut the aggregate rock to be tested into square blocks to obtain aggregate rock blocks; and polish the surface of the aggregate rock blocks to be tested to a smooth finish; (2) Two ultra-thin pads are attached to both sides of the surface to be tested of the aggregate rock block, and the thickness of the ultra-thin pads is 1μm~1000μm; (3) Apply the asphalt to be tested to the surface of the remaining aggregate rock block after pasting the ultra-thin gasket, and scrape the asphalt to be tested flat with the ultra-thin gasket to obtain an asphalt-aggregate adhesion sample with an asphalt film, and wait for the asphalt film to fully wet the surface of the aggregate rock block to be tested. (4) Adhere the fully soaked asphalt-aggregate adhesion sample to the test stand with glue; (5) Fix the test stand with the asphalt-aggregate adhesion sample pasted on it onto the nano / micro scratch tester and perform a scratch test; The nano / micro scratch test process is divided into two stages: In the first stage, the nano / micro indenter is pressed into the asphalt film and slips, but has not yet contacted the test surface of the aggregate rock block; In the second stage, the nano / micro indenter contacts the test surface of the aggregate rock block and continues to slide, peeling the asphalt film off the test surface of the aggregate rock block; Record the vertical pressure F and the lateral force F of the indenter. L 1. Indentation depth h; Record the sliding distance L1 of the first stage indenter and the sliding distance L2 of the second stage indenter; (6) Calculate the asphalt-aggregate interfacial adhesion force F according to the following formula. S : ； Among them, F S : Asphalt-aggregate interfacial adhesion force, unit N; F: Vertical pressure of the indenter, unit N; F L : The lateral force of the indenter, in N; F R : Lateral resistance of the asphalt film to the indenter, in N; h max The maximum penetration depth of the indenter into the asphalt film during the first stage, in mm; h ’ max L1: Maximum indentation depth of the second-stage indenter into the asphalt film, in mm; L2: Sliding distance of the first-stage indenter, in mm; L3: Sliding distance of the second-stage indenter, in mm.

2. The method for testing the adhesion force of asphalt-aggregate interface scratches according to claim 1, characterized in that, In step (1), the side length of the aggregate rock block is 1.5cm and the height is 0.5~1cm.

3. The method for testing the asphalt-aggregate interface adhesion force by scratch according to claim 1, characterized in that, In step (1), the process of polishing the surface to be tested is to polish it with 200 grit, 400 grit and 800 grit sandpaper in sequence.

4. The method for testing the adhesion force of asphalt-aggregate interface by scratch according to claim 1, characterized in that, In step (2), the length of each ultrathin pad is the same as the side length of the aggregate rock block, and the width is 2~3mm.

5. The method for testing the asphalt-aggregate interface adhesion force by scratch according to claim 1, characterized in that, In step (2), the ultra-thin gasket is made of PVC sheet.

6. The method for testing the adhesion force of asphalt-aggregate interface by scratch according to claim 1, characterized in that, In step (3), the process of fully wetting the surface of the aggregate rock block to be tested with the asphalt film is as follows: the asphalt-aggregate adhesion sample is placed in a sealed container with a relative humidity of 50%-70% and left to stand for 4 to 24 hours.

7. The method for testing the asphalt-aggregate interface adhesion force by scratch according to claim 1, characterized in that, In step (4), the test platform is made of an aluminum block with a diameter of 3cm and a height of 2cm.

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