A testing device and testing method for asphalt mastic bonded specimens

Abstract

This invention discloses a testing device and method for asphalt mastic adhesive samples, belonging to the field of engineering material testing technology, and can solve the problem that the adhesive properties of asphalt mastic cannot be specifically tested. The device includes: an adhesive strength tester, a steel plate, an asphalt mastic sample, and a pull-out block stacked sequentially from bottom to top. The pull-out block includes a pull-out base and a pull-out head; the pull-out base is located on the asphalt mastic sample; the adhesive strength tester is connected to the pull-out head and is used to test the adhesive sample. This invention can quantitatively evaluate the adhesive properties of asphalt mastic, including adhesive strength and failure type, providing a reliable basis for product development and quality control in the laboratory.

Description

Technical Field

[0001] This invention relates to a testing device and method for asphalt mastic bonding samples, belonging to the field of engineering material testing technology. Background Technology

[0002] In hydropower and water conservancy projects, asphalt concrete panels are commonly used as seepage prevention materials. These panels consist of three layers: a leveling and bonding layer, a seepage prevention layer, and a sealing layer, from bottom to top. The sealing layer, as the outermost surface material, is crucial; if damaged, the inner seepage prevention layer will be exposed, significantly increasing the risk of overall failure of the seepage prevention system.

[0003] The sealing layer material is asphalt mastic, which is composed of asphalt, fillers, and additives in a specific ratio. Existing tests for asphalt mastic include low-temperature crack resistance test, softening point test, flexibility test, and slope flow test. These four tests are used to characterize the low-temperature crack resistance and high-temperature flow performance.

[0004] However, as the surface structure, the sealing layer also needs to have its adhesive properties tested. The test results can assess the bonding quality and thus predict the risk of material debonding and peeling. However, there is currently no testing method for the adhesive properties of asphalt mastic itself. Summary of the Invention

[0005] The present invention provides a testing device for asphalt mastic bonding samples, including a bonding strength tester, and steel plates, asphalt mastic samples and pull-out blocks stacked from bottom to top. The drawing block includes a drawing base and a drawing head; The pull-out base is located on the asphalt mastic sample; The adhesive strength tester is connected to the pull-out head and is used to test the adhesive sample.

[0006] This invention also provides a test method for asphalt mastic bonding samples, comprising: Preparation of asphalt mastic; The asphalt mold is placed horizontally on the preheated steel plate; the asphalt mastic is poured onto the asphalt mold, and after cooling, the asphalt mold is removed to obtain an asphalt mastic sample; the asphalt mastic sample is located on the steel plate. The preheated drawing block is placed on the asphalt mastic sample and cooled to room temperature for a preset time to obtain the bonded sample; the bonded sample consists of the steel plate, the asphalt mastic sample and the drawing block from bottom to top. The adhesive strength tester is connected to the pull-out block on the adhesive sample, and the adhesive strength and failure interface information of the adhesive sample are obtained by detection.

[0007] Specifically, the bonding strength of the bonded sample is obtained by testing: Obtain the bonding area of ​​the bonding sample; When the handle of the adhesive strength tester is rotated to the maximum adhesive force, the maximum adhesive force is recorded; The bonding strength is determined based on the bonding area and the maximum bonding force.

[0008] The preheating temperature of the steel plate and the drawing block is 80℃~100℃.

[0009] Further, the preparation of asphalt mastic includes: Mix the asphalt and additives for 1 to 2 minutes at a temperature of 130°C to 190°C. Add filler and stir for 3 to 5 minutes at a temperature of 150°C to 210°C to obtain asphalt mastic.

[0010] The mass ratio of asphalt to filler is 30:70 to 40:60.

[0011] The additive is one or more of the following: polymer modifier, fiber, warm mix agent, regenerator, and anti-stripping agent; Different types of additives require different stirring temperatures.

[0012] Furthermore, the preheated pull-out block is placed on the asphalt mastic sample, specifically including: Determine whether the surface of the asphalt mastic sample meets the preset conditions. If so, place the preheated pull block at the center of the asphalt mastic sample.

[0013] The bonding strength is determined based on the bonding area and the maximum bonding force, specifically as follows: The ratio of the maximum adhesive force to the adhesive area is the adhesive strength.

[0014] Wherein, the bonding strength is the arithmetic mean of the bonding strengths of multiple bonding samples.

[0015] Furthermore, when the difference between any extreme value and the median value of the bonding strength of multiple bonded samples exceeds a preset threshold, the median value is taken as the bonding strength. When the difference between the two extreme values ​​of the bonding strength of multiple bonded samples and the median value both exceed a preset threshold, the bonded samples are re-prepared.

[0016] The beneficial effects of this invention include: the testing method for asphalt mastic bonding samples provided in this embodiment involves placing an asphalt mold horizontally on a preheated steel plate, pouring the asphalt mastic onto the mold, cooling it, removing the mold, and obtaining an asphalt mastic sample. A preheated pull-out block is then placed on the asphalt mastic sample, and after cooling to room temperature for a preset time, a bonding sample is obtained. Finally, a bonding strength tester is connected to the pull-out block on the bonding sample, and the bonding strength and failure interface morphology of the bonding sample are obtained by testing. This testing method is highly versatile, provides objective and comparable results, and can quantitatively evaluate the bonding performance of asphalt mastic, including bonding strength and failure type, providing a reliable basis for product development and quality control in the laboratory. Attached Figure Description

[0017] Figure 1 The following is a schematic diagram of the structure of the adhesive strength tester provided in the embodiment of the present invention, wherein (a) is a three-dimensional structural schematic diagram of the adhesive strength tester provided in the embodiment of the present invention, and (b) is a planar structural schematic diagram of the adhesive strength tester provided in the embodiment of the present invention; Figure 2 This is a schematic diagram of the pull block structure provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the asphalt mold structure provided in an embodiment of the present invention; Figure 4 A schematic diagram of a test method for asphalt mastic bonding samples provided in an embodiment of the present invention; Figure 5 The above are schematic diagrams of the structure of the adhesive sample provided in the embodiments of the present invention, wherein (a) is a schematic diagram of the planar structure of the adhesive sample provided in the embodiments of the present invention, and (b) is a schematic diagram of the three-dimensional structure of the adhesive sample provided in the embodiments of the present invention. Figure 6 This is a schematic diagram of the failure interface morphology of the cohesive failure type provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the failure interface morphology of adhesion failure provided in an embodiment of the present invention; Figure 8 The failure interface morphology of the adhesive sample 1 provided in the embodiment of the present invention is shown in (a) the failure interface morphology of the steel plate of the adhesive sample 1 provided in the embodiment of the present invention, and (b) the failure interface morphology of the pull-out block of the adhesive sample 1 provided in the embodiment of the present invention. Figure 9 The failure interface morphology of the adhesive sample 2 provided in the embodiment of the present invention is shown in (a) the failure interface morphology of the steel plate of the adhesive sample 2 provided in the embodiment of the present invention, and (b) the failure interface morphology of the pull-out block of the adhesive sample 2 provided in the embodiment of the present invention. Figure 10The failure interface morphology of the adhesive sample 3 provided in the embodiment of the present invention; wherein (a) is the failure interface morphology of the steel plate of the adhesive sample 3 provided in the embodiment of the present invention, and (b) is the failure interface morphology of the pull-out block of the adhesive sample 3 provided in the embodiment of the present invention.

[0018] In the diagram: 101, support system; 102, loading system; 103, digital display system; 104, connecting component; 201, drawing base; 202, drawing head; 301, mold frame; 302, hollow part; 4, steel plate; 5, asphalt mastic. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a testing device for asphalt mastic bonding samples, including a bonding strength tester, and steel plates, asphalt mastic samples, and pull-out blocks stacked sequentially from bottom to top. Figure 1 (a) is a three-dimensional structural diagram of the adhesive strength tester provided in an embodiment of the present invention. Figure 1 (b) is a schematic diagram of the planar structure of the adhesive strength tester provided in an embodiment of the present invention, as shown in Figure 1. Figure 1 As shown, the adhesive strength tester includes: a support system 101, a loading system 102, a digital display system 103, and a connecting component 104. Adhesive strength testers are existing technology, and will not be described in detail here.

[0021] The drawing block includes a drawing base 201 and a drawing head 202; Figure 2 This is a schematic diagram of the drawing block structure provided in an embodiment of the present invention, as shown below. Figure 2 As shown, it includes: a pull-out base 201 and a pull-out head 202; The pull-out base 201 is located on the asphalt mastic sample and is bonded to the asphalt mastic sample. The pull-out head 202 is connected to the adhesive strength tester 104. Specifically, the outer ring of the connecting component 104 of the adhesive strength tester is threaded, the inner ring of the pull-out head 202 is threaded, and the connecting component 104 is threaded to the pull-out head 202.

[0022] In this embodiment of the invention, the asphalt mastic sample is prepared by an asphalt mold. Figure 3 This is a schematic diagram of the asphalt mold structure provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the mold includes: a mold frame 301, and a hollow portion 302 on the mold frame 301, which is used to fill asphalt mastic. The surface of the asphalt mold is coated with polytetrafluoroethylene (PTFE), which does not stick to the asphalt, facilitating demolding.

[0023] In this embodiment of the invention, the steel plate has dimensions of 200mm × 200mm, a thickness greater than 2mm, and a smooth surface. The asphalt mold has a height of 2mm and an inner diameter of 50mm × 50mm. The drawing base 201 has dimensions of 40mm × 40mm × 8mm, with an allowable deviation of ±0.5mm, and is made of 45# steel or chrome steel.

[0024] It should be noted that the size of the pull-out base 201 is smaller than that of the asphalt mold. This reduces the "edge effect" and ensures that the failure occurs inside the adhesive layer that needs to be tested, rather than premature failure caused by stress concentration or defects at the edge of the asphalt mastic. This allows the adhesive strength obtained from subsequent tests to more accurately reflect the adhesive performance of the adhesive sample itself.

[0025] The adhesive strength tester is connected to the pull-out head 202 and is used to detect the adhesive strength and failure interface information of the adhesive sample.

[0026] This invention also provides a test method for asphalt mastic bonding samples, such as... Figure 4 As shown, it specifically includes: S1. Preparation of asphalt mastic; In this embodiment of the invention, asphalt and filler are first placed in an oven at 170℃~190℃ and kept at that temperature for 2 hours until the asphalt melts and is ready for use. If the additive is in powder form, it is also placed in the oven for heating; if the additive is in liquid form, heating is not required.

[0027] After the raw materials of asphalt, filler, and additives are prepared, the asphalt and filler are weighed according to a certain ratio. In practical applications, the mass ratio of asphalt to filler is 30:70 to 40:60, and the amount of additives used can be adjusted according to the specific type.

[0028] In the embodiments of this invention, the filler can be limestone powder, cement, montmorillonite, hydrated lime, fly ash, etc.; the additive can be a polymer modifier, such as SBS (Styrene-Butadiene-Styrene triblock copolymer), SBR (Styrene-Butadiene Rubber), EVA (Ethylene-Vinyl Acetate Copolymer), PE (Polyethylene), etc., or it can be fiber, anti-stripping agent, warm mix agent or nanoparticles, etc. In actual testing, additives may not be added.

[0029] In this embodiment of the invention, different additives correspond to different heating temperatures. The heating temperatures corresponding to different additives and the resulting asphalt mastic temperature are shown in Table 1: Table 1. Heating temperatures and obtained asphalt mastic temperatures for different additives.

[0030] In this embodiment of the invention, after determining the proportions of each component in the asphalt mastic, the asphalt and additives are first poured into a mixing pot and stirred for 1-2 minutes, with the stirring temperature determined according to Table 1; then filler is added and stirred for 3-5 minutes, with the stirring temperature determined according to Table 1, thereby obtaining the asphalt mastic. To ensure uniform mixing of the asphalt mastic, the filler can be added to the asphalt and additive mixture in multiple batches. This embodiment of the invention does not limit the specific selection of asphalt, filler, and additives; the heating temperature for each additive is determined according to the type of additive.

[0031] S2. Place the asphalt mold horizontally on the preheated steel plate; pour the asphalt mastic onto the asphalt mold, and remove the asphalt mold after cooling to obtain an asphalt mastic sample. Currently, various bonding tests use concrete or stone slabs as substrate materials. However, concrete or stone slabs have porous, uneven surfaces and fluctuating performance. These physical properties, chemical properties, and mineral composition directly affect the bonding performance of asphalt mastic. For example, rough, alkaline stone slabs with low SiO2 (Silicon Dioxide) content often achieve higher bonding strength. Therefore, tests using stone slabs as substrates make it difficult to compare test results across different substrates and to develop universal testing methods. In this embodiment of the invention, steel plates are selected as the substrate because steel plates are homogeneous materials with smooth surfaces, are not easily deformed, and are readily available. This ensures consistent test conditions across multiple tests, improving the versatility and reproducibility of the testing method.

[0032] It should be noted that the failure interface information obtained in this application focuses more on the failure interface information corresponding to cohesive failure, rather than the failure interface information corresponding to adhesive failure. In other words, this application focuses on detecting the cohesive force of the asphalt mastic, rather than the adhesive force. Steel plates and asphalt materials have excellent adhesion properties, which can effectively prevent adhesion and debonding during the pull-out process, forcing the failure to occur inside the asphalt mastic.

[0033] In the prior art, the structure of the asphalt panel is "asphalt mastic - asphalt anti-seepage layer - leveling and bonding layer" from top to bottom. In this structure, the asphalt mastic is in direct contact with the asphalt anti-seepage layer, and the material of the contact surface is "asphalt-asphalt". In the embodiment of the present invention, a steel plate that has good adhesion to asphalt is selected as the substrate, and the material of the contact surface is "asphalt-steel". This structure can truly reflect the state of cohesion in the project.

[0034] It should also be noted that stone may absorb water and soften, crack, or precipitate salts when exposed to water or freeze-thaw cycles, affecting the reliability of test results. Steel plates, however, do not absorb water, expand in volume, undergo chemical decomposition, or change their surface properties under simulated environmental conditions such as immersion and freeze-thaw cycles, and therefore will not cause additional interference to the testing of asphalt mastic.

[0035] To obtain accurate test results, the steel plate is first pretreated in this embodiment of the invention. Specifically, the steel plate is cleaned sequentially with detergent, distilled water, and anhydrous ethanol, and then heated in an oven to 80℃~100℃ for later use. When using, the steel plate is removed from the oven and placed horizontally, with the asphalt mold placed on the steel plate. The asphalt mastic is poured onto the asphalt mold from the edges towards the center, gently agitated to remove small air bubbles and smooth the surface. If the asphalt mastic sample protrudes excessively from the asphalt mold, it is leveled from the center outwards using a hot scraper. After slight cooling, the asphalt mold is carefully removed, yielding an asphalt mastic sample measuring 50mm×50mm×2mm.

[0036] S3. Place the preheated pull block on the asphalt mastic sample, and after cooling to room temperature for a preset time, obtain the bonded sample. Figure 5 (a) is a schematic diagram of the planar structure of the adhesive sample provided in an embodiment of the present invention. Figure 5 (b) is a schematic diagram of the three-dimensional structure of the adhesive sample provided in an embodiment of the present invention, as shown in Figure 1. Figure 5 As shown, from bottom to top, the components are: steel plate 4, asphalt mastic 5, and drawing base 201. Further, before placing the preheated drawing block on the asphalt mastic sample, it is determined whether the surface of the asphalt mastic sample meets preset conditions. For example, by lightly touching the surface of the asphalt mastic sample with your hand, if your hand does not stick to the asphalt mastic sample, or if the surface of the asphalt mastic sample is intact and has a certain supporting force, the preheated drawing block is placed in the center of the asphalt mastic sample.

[0037] After cooling to room temperature, the sample is stored in an environment below 25°C for at least 24 hours to obtain the bonding sample of the "steel plate-asphalt mastic-pull block" combination.

[0038] S4. Connect the adhesive strength tester to the pull-out block on the adhesive sample, and obtain the adhesive strength and failure interface information of the adhesive sample by detection.

[0039] The information on the failure interface includes the failure interface morphology and failure type. Failure types include cohesive failure (CF) and adhesive failure (AF). If both failure types occur, an approximate percentage of failure area for each type should be given after each type. Figure 6 A schematic diagram of the failure interface morphology for cohesive failure type; Figure 7 This is a schematic diagram of the interface morphology of adhesion failure.

[0040] The bonding strength of the bonded sample is obtained by testing, specifically including: Obtain the bonding area of ​​the bonding sample; When the handle of the adhesive strength tester is rotated to the maximum adhesive force, the maximum adhesive force is recorded; The bonding strength is determined based on the maximum bonding force and the bonding area.

[0041] In this embodiment of the invention, the test is conducted in an environment of 21℃~25℃. The bonded sample is placed at this temperature for at least 2 hours. Then, the bond strength tester is connected to the pull-out block, the handle is adjusted to the maximum range, zeroed, and the handle is rotated evenly until the bond force is maximum. The ratio of the maximum bond force to the bonded area is then taken as the bond strength.

[0042] In this embodiment of the invention, it is set Bond strength, in MPa; Maximum adhesive force, in N; The bonding area is in mm. 2 ;but .

[0043] In practical applications, the arithmetic mean of the bond strengths obtained from multiple bonded samples can be used as the bond strength. Alternatively, if the difference between any extreme value and the median value of the bond strengths from multiple bonded samples exceeds a preset threshold, the median value can be used as the bond strength. If the differences between the two extreme values ​​and the median value of the bond strengths from multiple bonded samples both exceed the preset threshold, the bonded samples should be prepared again. For example, assuming there are three bonded samples, if the difference between the maximum or minimum bond strength and the median value exceeds 15% of the median value, the median value should be used. If the differences between the maximum and minimum bond strengths and the median value from the three samples both exceed 15% of the median value, the test should be repeated.

[0044] In this embodiment of the invention, three bonding samples were prepared, and tests were conducted on these three samples respectively. A total of three sets of tests were performed, as shown in Table 2. Table 2. Test parameters and results of three bonding samples in the embodiments of the present invention.

[0045] In the first set of bonding test samples, the excessively high filler ratio and insufficient stirring temperature jointly led to decreased mixing uniformity and caused filler agglomeration. Damage mainly occurred in the agglomerated areas, and dense, small granular protrusions were visible at the steel plate failure interface. Figure 8 (a) shows the failure interface morphology of the steel plate in the bonded sample 1. Figure 8 (b) in the figure shows the failure interface morphology of the pull-out block of the bonded sample 1.

[0046] In the second group of bonded test specimens, the pull-out block and steel plate were not preheated, resulting in poor adhesion between them and the asphalt mastic specimens in localized areas, leading to an adhesion failure rate as high as 60%. However, the bonded specimens themselves exhibited good adhesion performance, with stress striations observed around the failure surface, indicating a high actual interfacial bond strength. Figure 9 (a) shows the failure interface morphology of the steel plate in the bonded sample 2. Figure 9 (b) in the figure shows the failure interface morphology of the pull-out block of the bonded sample 2.

[0047] In the third group of bonding test samples, due to the lack of preheating of the pull-out blocks, there were small areas of incomplete bonding. However, stress marks were visible around the fracture surface, indicating that the filler was well dispersed and the interface was tightly bonded. Figure 10 (a) shows the failure interface morphology of the steel plate in the bonded sample 3. Figure 10 (b) shows the failure interface morphology of the pull-out block of the bonded sample 3, and the bond strength is significantly higher than that of the bonded sample 1.

[0048] The testing method for asphalt mastic bonding samples provided in this invention involves placing an asphalt mold horizontally on a preheated steel plate, pouring the asphalt mastic onto the mold, and then removing the mold after cooling to obtain an asphalt mastic sample. A preheated pull-out block is then placed on the asphalt mastic sample, and after cooling to room temperature for a preset time, a bonding sample is obtained. Finally, a bonding strength tester is connected to the pull-out block on the bonding sample, and the bonding strength and failure interface morphology of the bonding sample are obtained by testing. This testing method is highly versatile, and the results are objective and comparable. It can quantitatively evaluate the bonding performance of asphalt mastic, including bonding strength and failure type, providing a reliable basis for product development and quality control in the laboratory. Because asphalt is a temperature-sensitive material, strict temperature control is implemented at every stage of the bonding sample preparation process. Different heating temperatures are selected based on the different additives used, thereby improving the testing accuracy of the bonding samples. By pouring asphalt mastic into an asphalt mold, the thickness of the asphalt mastic sample is made consistent with the sealing layer of the hydraulic asphalt concrete panel, accurately reflecting the true bonding performance of the asphalt mastic in actual engineering. The size of the asphalt mold is larger than the base size of the pull-out block, reducing the "edge effect" and ensuring that failure occurs within the bonding layer to be tested, rather than premature failure caused by stress concentration or defects at the edges of the asphalt mastic. This allows the tested bonding strength to more accurately reflect the bonding performance of the bonding sample itself.

[0049] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A testing device for asphalt mastic bonding samples, characterized in that, Includes an adhesive strength tester, steel plates, asphalt mastic samples, and pull-out blocks stacked from bottom to top; The drawing block includes a drawing base and a drawing head; The pull-out base is located on the asphalt mastic sample; The adhesive strength tester is connected to the pull-out head and is used to test the adhesive sample.

2. A test method for asphalt mastic bonding samples, characterized in that, include: Preparation of asphalt mastic; Place the asphalt mold horizontally on the preheated steel plate; The asphalt mastic is poured onto the asphalt mold, cooled, and then the asphalt mold is removed to obtain an asphalt mastic sample; the asphalt mastic sample is located on a steel plate; The preheated drawing block is placed on the asphalt mastic sample and cooled to room temperature for a preset time to obtain the bonded sample; the bonded sample consists of the steel plate, the asphalt mastic sample and the drawing block from bottom to top. The adhesive strength tester is connected to the pull-out block on the adhesive sample, and the adhesive strength and failure interface information of the adhesive sample are obtained by detection.

3. The test method for asphalt mastic bonding samples according to claim 2, characterized in that, The bonding strength of the bonded sample was obtained by testing, specifically as follows: Obtain the bonding area of ​​the bonding sample; When the handle of the adhesive strength tester is rotated to the maximum adhesive force, the maximum adhesive force is recorded; The bonding strength is determined based on the bonding area and the maximum bonding force.

4. The test method for asphalt mastic bonding samples according to claim 2, characterized in that, The preheating temperature of the steel plate and the drawing block is 80℃~100℃.

5. The test method for asphalt mastic bonding samples according to claim 2, characterized in that, The preparation of asphalt mastic includes: Mix the asphalt and additives for 1 to 2 minutes at a temperature of 130°C to 190°C. Add filler and stir for 3 to 5 minutes at a temperature of 150°C to 210°C to obtain asphalt mastic.

6. The test method for asphalt mastic bonding samples according to claim 5, characterized in that, The mass ratio of asphalt to filler is 30:70 to 40:

60.

7. The test method for asphalt mastic bonding samples according to claim 5, characterized in that, The additive is one or more of the following: polymer modifier, fiber, warm mix agent, regenerator, and anti-stripping agent; Different types of additives require different stirring temperatures.

8. The test method for asphalt mastic bonding samples according to claim 2, characterized in that, The preheated pull block is placed on the asphalt mastic sample, specifically including: Determine whether the surface of the asphalt mastic sample meets the preset conditions. If so, place the preheated pull block at the center of the asphalt mastic sample.

9. The test method for asphalt mastic bonding samples according to claim 3, characterized in that, The bonding strength is determined based on the bonding area and the maximum bonding force, specifically as follows: The ratio of the maximum adhesive force to the adhesive area is the adhesive strength.

10. The test method for asphalt mastic bonding samples according to claim 9, characterized in that, When the difference between any extreme value and the median value of the bonding strength of multiple bonded samples exceeds a preset threshold, the median value is taken as the bonding strength. When the difference between the two extreme values ​​of the bonding strength of multiple bonded samples and the median value both exceed a preset threshold, the bonded samples are re-prepared.

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