Method for evaluating water stability of asphalt mixture

Abstract

The invention discloses a method for evaluating the water stability of an asphalt mixture, and belongs to the technical field of road engineering. The method comprises the following steps: adhering silicon dioxide to a needle point of an atomic force microscope, modifying with asphalt to be tested, and calibrating to obtain a colloid probe; testing the hydrophilic aggregate substrate by using a colloid probe to obtain an AFM-interaction force test value; calculating by using the surface potential test values of the to-be-tested asphalt and the to-be-tested aggregate to obtain a Zeta-acting force calculated value; testing methods of the standard asphalt and the standard aggregate are the same, and obtaining an AFM-interaction force standard value and a Zeta-acting force standard value; and comparing the AFM-interaction force test value with the AFM-interaction force standard value, and comparing the Zeta-acting force calculation value with the Zeta-acting force standard value to evaluate the water stability of the asphalt mixture. According to the method, the water stability can be judged without preparing the asphalt and the aggregate into a mixture, the test period is short, and the operation is simple and convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering, and more particularly to a method for evaluating the water stability of asphalt mixtures. Background Art

[0002] As an important part of road engineering, the water stability performance of asphalt mixtures is directly related to the service life and performance stability of road surfaces. In recent years, with the aggravation of environmental pollution, the erosion problems of asphalt pavements caused by environmental factors such as acid rain, marine salt spray and saline-alkali land have become increasingly serious. Waters with different acid-base properties, such as the aqueous solutions in acid rain areas, coastal areas or saline-alkali lands, may cause varying degrees of water damage to asphalt pavements. Acid rain can enter the asphalt pavement through cracks and pores, affecting the adhesion between asphalt and aggregates, while the salts in saline-alkali soils can also enter the pavement through rainwater, further exacerbating the weakening of the adhesion between asphalt and aggregates.

[0003] Existing studies have shown that the acid-base property of water has a significant impact on the water stability of asphalt pavements. For example, a higher pH alkaline environment will increase the degree of stripping between asphalt and aggregates, resulting in a significant decline in the water stability performance of asphalt mixtures.

[0004] Traditional evaluation methods for aggregate-asphalt adhesion are mainly based on the macroscopic scale, directly testing the prepared asphalt mixtures, such as through stripping tests and immersion Marshall tests, etc. These methods can reflect the water stability of asphalt mixtures to a certain extent, but there are problems such as long test cycles and complex operations, and the influence of the acid-base property of the environment (such as acid rain areas and saline-alkali lands) on the water stability of asphalt mixtures cannot be reflected during the test, resulting in a certain deviation between the evaluation results of the water stability of asphalt mixtures and the actual situation. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method for evaluating the water stability of asphalt mixtures, which can judge the water stability without preparing asphalt and aggregates into mixtures, has a short test cycle and is easy to operate.

[0006] The first object of the present invention is to provide a method for evaluating the water stability of asphalt mixtures, comprising the following steps:

[0007] Attach silica to the tip of an atomic force microscope, and modify and calibrate it with the asphalt to be tested to obtain a colloidal probe; subject the aggregate to be tested to a hydrophilic treatment to prepare a hydrophilic aggregate substrate.

[0008] Under the tapping mode, use the colloidal probe to test the hydrophilic aggregate substrate to obtain the AFM-interaction force test value between the asphalt to be tested and the aggregate to be tested.

[0009] The surface potential test values of the asphalt to be tested and the aggregate to be tested are measured respectively by using a Zeta potential analyzer; the calculated value of the Zeta-force between the asphalt to be tested and the aggregate to be tested is obtained by performing DLVO theory calculation using the surface potential test values.

[0010] Referring to the above method, the standard asphalt and the standard aggregate in the standard specimen of the asphalt mixture are tested to obtain the standard value of the AFM-interaction force and the standard value of the Zeta-force between the standard asphalt and the standard aggregate. The specific operation steps are as follows: silica is adhered to the tip of the atomic force microscope and modified and calibrated with standard asphalt to obtain a colloidal probe; the standard aggregate is subjected to a hydrophilic treatment to prepare a hydrophilic aggregate substrate. In the tapping mode, the AFM-interaction force standard value between the standard asphalt and the standard aggregate is obtained by using the colloidal probe to test the hydrophilic aggregate substrate.

[0011] The surface potential test values of the standard asphalt and the standard aggregate are measured respectively by using a Zeta potential analyzer; the calculated value of the Zeta-force between the standard asphalt and the standard aggregate is obtained by performing DLVO theory calculation using the surface potential test values.

[0012] Compare the measured value of the AFM-interaction force with the standard value of the AFM-interaction force, and the calculated value of the Zeta-force with the standard value of the Zeta-force. When the following conditions are met, the water stability of the asphalt mixture meets the usage requirements.

[0013] When the measured value of the AFM-interaction force between the asphalt to be tested and the aggregate to be tested ≥ the standard value of the AFM-interaction force between the standard asphalt and the standard aggregate, and the calculated value of the Zeta-force between the asphalt to be tested and the hydrophilic aggregate to be tested ≥ the standard value of the Zeta-force between the standard asphalt and the standard aggregate, the water stability of the asphalt mixture meets the requirements. On the contrary, when the measured value of the AFM-interaction force between the asphalt to be tested and the aggregate to be tested < the standard value of the AFM-interaction force between the standard asphalt and the standard aggregate; the calculated value of the Zeta-force between the asphalt to be tested and the hydrophilic aggregate to be tested < the standard value of the Zeta-force between the standard asphalt and the standard aggregate, it indicates that the water stability of the asphalt mixture does not meet the requirements.

[0014] It should be noted that the measured value of the Zeta potential is used to calculate the force in combination with the DLVO theory. If the measured value of the AFM-interaction force obtained by AFM testing meets the requirements, the force obtained by the Zeta potential also meets the requirements.

[0015] In a preferred embodiment of the present invention, the adhesion thickness of the silica is 3 nm - 5 nm.

[0016] In a preferred embodiment of the present invention, the method for modifying the pretreatment probe with the asphalt to be tested is as follows: the asphalt to be tested is dispersed in toluene to prepare an asphalt solution; the pretreatment probe is soaked in the asphalt solution.

[0017] In a preferred embodiment of the present invention, the concentration of the asphalt solution is 10 mg / ml to 15 mg / ml.

[0018] In a preferred embodiment of the present invention, the soaking time is 5 to 7 minutes.

[0019] In a preferred embodiment of the present invention, the hydrophilic treatment is carried out in a mixed solution of sulfuric acid and hydrogen peroxide at 90°C to 95°C for 30 minutes to 35 minutes.

[0020] In a preferred embodiment of the present invention, in the mixed solution of sulfuric acid and hydrogen peroxide, the volume percentage of sulfuric acid is 70% to 75%, and the rest is hydrogen peroxide, with a total of 100%.

[0021] In a preferred embodiment of the present invention, when using a colloidal probe to test the hydrophilic aggregate substrate, the applied pressure is 10 mN / m.

[0022] In a preferred embodiment of the present invention, the standard specimen of the asphalt mixture is a mixture specimen that meets the adhesion test and water stability test standards.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Using the AFM colloidal probe technology to test the water stability of asphalt and aggregate, there is no need to prepare mixture specimens, the test speed is fast, and the water stability of asphalt mixture can be accurately evaluated within two hours. The AFM colloidal probe technology can measure the interaction force between asphalt and aggregate at the microscale and quickly obtain high-precision test data. This method can accurately evaluate the adhesion performance between asphalt and aggregate and provide a reliable evaluation result for the water stability of asphalt mixture.

[0025] (2) By applying the AFM colloidal probe technology and Zeta potential test, combined with the calculation and analysis of the DLVO theory, it is possible to quantitatively evaluate the stability of the asphalt-aggregate system in various chemical environments, especially to effectively predict its water stability under different pH values and salt concentrations. It can accurately and quickly evaluate the water stability of asphalt mixture under different pH values and salt solution conditions, and effectively prevent the water damage effects that the aqueous solution in acid rain areas, coastal areas or saline-alkali lands may have on asphalt pavements. Description of the Drawings

[0026] Figure 1The long-range forces and adhesion forces between matrix asphalt and aggregates at different pH values. Among them, a is the long-range force at pH 2, b is the long-range force at pH 4, c is the long-range force at pH 6, d is the long-range force at pH 8, e is the long-range force at pH 10, and f is the adhesion force between matrix asphalt and aggregates at different pH values.

[0027] Figure 2 The long-range forces and adhesion forces between SBS modified asphalt and aggregates at different pH values. Among them, a is the long-range force at pH 2, b is the long-range force at pH 4, c is the long-range force at pH 6, d is the long-range force at pH 8, e is the long-range force at pH 10, and f is the adhesion force between SBS modified asphalt and aggregates at different pH values. Specific implementation manners

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] The application of atomic force microscope (AFM) colloidal probe technology in material surface science is becoming more and more extensive. The AFM technology can measure the mechanical properties of the material surface at the nanoscale and can accurately determine the microscopic interaction forces between asphalt and aggregates. At the same time, through Zeta potential testing, the surface charge characteristics of asphalt and aggregates under different acid-base conditions can be obtained. These microscopic testing methods provide a new perspective for studying the adhesion mechanism between asphalt and aggregates. In addition, the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory, as a classical colloidal interaction theory, can well describe the interaction forces between particles, including van der Waals forces and electrostatic repulsion forces. Combining the DLVO theory with microscopic testing techniques can systematically analyze the water stability of the asphalt-aggregate system in different chemical environments, thereby providing a scientific basis and technical support for the design of asphalt mixtures and the improvement of the water damage resistance performance of pavements. Specifically, the present invention provides an evaluation method for the water stability of asphalt mixtures, including the following steps:

[0030] Using an Atomic Force Microscope (AFM) for colloidal probe testing can measure the interaction force between asphalt and aggregates at the nanoscale. The tip of the AFM probe is made of materials such as silica. The silica is adhered to the tip of the atomic force microscope and modified and calibrated with the asphalt to be tested to obtain a colloidal probe. The shape of the silica determines the shape of the asphalt, and it can simulate an asphalt droplet. The aggregate to be tested is prepared into a hydrophilic aggregate substrate by hydrophilic treatment.

[0031] Using the colloidal probe to test the hydrophilic aggregate substrate to obtain the AFM-interaction force test value between the asphalt to be tested and the aggregate to be tested. The AFM-interaction force is a general term for long-range force and adhesion force. During the testing process, when the motor drives the hydrophilic aggregate substrate to move upward close to the colloidal probe, the long-range force between the asphalt and the aggregate surface can be obtained. When the asphalt and the aggregate come into contact and then immediately separate, the adhesion force between the asphalt and the aggregate surface can be obtained at this time.

[0032] The Zeta potential determines the electrostatic interaction between asphalt and aggregates. When the potential is relatively high, the electrostatic repulsion increases, which may lead to a decrease in the adhesion force. On the contrary, it may enhance the adhesion performance. By measuring the Zeta potential under different conditions, the water stability can be evaluated more comprehensively. Using a Zeta potential analyzer to measure the surface potential test values of the asphalt to be tested and the aggregate to be tested respectively. Using the surface potential test values for DLVO theory calculation to obtain the Zeta-force calculation value between the asphalt to be tested and the aggregate to be tested. The DLVO theory provides a framework for understanding the interaction between asphalt and aggregates. By analyzing the influence of various forces, the water stability performance of asphalt mixtures under different environmental conditions can be quantitatively predicted. This predictive ability provides a scientific basis for the design and optimization of pavement materials.

[0033] Using an atomic force microscope to test the standard asphalt and standard aggregates in the standard specimen of asphalt mixture to obtain the standard value of the AFM-interaction force between the standard asphalt and standard aggregates.

[0034] Using a Zeta potential analyzer to measure the surface potential standard values of the standard asphalt and standard aggregates respectively. Using the surface potential standard values for DLVO theory calculation to obtain the Zeta-force standard value between the standard asphalt and standard aggregates.

[0035] Comparing the AFM-interaction force test value of the asphalt to be tested and the aggregate to be tested with the standard value of the AFM-interaction force between the standard asphalt and standard aggregates to obtain the AFM-interaction force comparison result.

[0036] Compare the calculated value of the Zeta-force between the asphalt to be tested and the hydrophilic aggregate to be tested with the standard value of the Zeta-force between the standard asphalt and the standard aggregate to obtain the force comparison result.

[0037] Evaluate the water stability of the asphalt mixture by comparing the measured value of the AFM-interaction force with the standard value of the AFM-interaction force, and the calculated value of the Zeta-force with the standard value of the Zeta-force.

[0038] It should be noted that the silica particles used in the present invention have a particle size of approximately 8 μm and are purchased from Duke Scientific Corporation, USA, for preparing colloidal probes. The Zhenhai No. 90 base asphalt, SBS modified asphalt, granite, basalt, Class A limestone and Class B limestone used in the present invention are from the Gansu Provincial Highway Maintenance Center. When preparing the hydrophilic solution in the present invention, the sulfuric acid is commercially available concentrated sulfuric acid with a concentration of 98%, and the mass concentration of hydrogen peroxide is 30%.

[0039] Example 1

[0040] S1. Prepare colloidal probes

[0041] S1.1. Attach silica to the end of the V-shaped tip cantilever of the atomic force microscope to obtain a pretreated probe, and the probe is placed for more than one day before use.

[0042] S1.2. Clean the tip with a plasma sputtering instrument for 10 min to remove possible contaminants on the probe to obtain a cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It can be understood that the possible contaminants on the probe need to be cleaned before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0043] S1.3. Immerse the cleaned probe in a toluene solution of Zhenhai No. 90 base asphalt with a concentration of 10 mg / ml for 5 minutes, take it out and dry it to complete the modification step, and then calibrate the elastic constant of the modified probe by the Thermal Tune method to obtain a colloidal probe.

[0044] S2. Prepare a hydrophilic aggregate substrate:

[0045] Clean granite fragments with an area of 8 mm × 8 mm (length × width) in a Piranha solution at 90 °C for 30 min. Then rinse with ultrapure water and ethanol, treat in an ultrasonic cleaner for 30 min, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H 2 O 2Composition. When cleaning with Piranha solution, just submerge the aggregates.

[0046] S3. Use AFM to test the adhesion force and long-range interaction force between asphalt and aggregates

[0047] Under the condition that the pH value of the aqueous solution is 2, the long-range interaction force and adhesion force between Zhenhai No. 90 base asphalt and granite were tested.

[0048] Test the interaction between the probe (simulating sand particles) and asphalt inside the "O" - ring seal. When testing, inject an aqueous solution with a pH value of 2 to submerge the probe and the asphalt surface, and then conduct the test after standing for 30 min.

[0049] The tapping mode is used for testing. The maximum pressure applied during the testing process is 10 mN / m. Three asphalt surfaces are tested for each group of samples, and five points are tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that needs to be overcome when the probe detaches from the aggregate surface varies greatly, the statistical quantity for each group of samples is 100 groups during statistics. To reduce the influence of the probe size on the long-range interaction force and adhesion force, the test results are all divided by the radius of the probe ball. All tests are carried out at room temperature (25 °C).

[0050] S3. Use a Zeta potential analyzer to measure the surface potentials of the asphalt to be tested and the hydrophilic aggregates to be tested respectively.

[0051] Use a Zeta potential analyzer to measure the Zeta potentials of the asphalt droplets and aggregate particles.

[0052] The preparation process of the asphalt emulsion is as follows. First, suck 5 mL of asphalt - toluene solution (10 mg / mL) into a flat-bottom flask. Then place the flask in a dry and ventilated place and wait for the toluene to volatilize. Finally, add 30 mL of ultrapure water to the flask and ultrasonically treat for 1 h to obtain the asphalt emulsion.

[0053] When preparing the aggregate particle suspension, select aggregate particles with a diameter of about 3 μm and prepare a suspension with a concentration of 0.1 g / mL.

[0054] All Zeta potential tests of the samples use 1 mmol / L KCl as the background electrolyte, and the tests are all carried out at room temperature (25 °C). Five parallel tests are set for each type of aggregate, and each group of samples is tested 5 times, and the average value is taken as the final result.

[0055] S4. Use the surface potential to calculate the calculated value of the Zeta - force between the asphalt to be tested and the aggregates to be tested in the aqueous solution through the DLVO theory

[0056] The force (F) between asphalt and aggregates in the aqueous solution total)It conforms to the classical DLVO (Derjaguin-Landau-Verwey-Overbeek) theory and is composed of the van der Waals force (F V ) and the electrostatic repulsion force of the double electric layer (F E ), as shown in Equation (1).

[0057] F total = F V + F E (1)

[0058] The van der Waals force is a function of the separation distance (D) between the substrate and the probe and can be calculated by Equation (2).

[0059]

[0060] Among them, A is the Hamaker constant, R is the radius of the colloidal probe, and D is the separation distance between the substrate and the colloidal probe; the Hamaker constant (A) of the fine aggregate component is the Hamaker constant of the powder ore, the Hamaker constant of the asphalt is the Hamaker constant of n-tetradecane, and the Hamaker constant (ABWF) of the asphalt / water / aggregate mixed system is calculated to be 6.5×10 -21 J. In addition, the electrostatic repulsion force of the double electric layer is calculated by the non-linear Poisson-Boltzmann equation (3).

[0061]

[0062] Among them, x is the axis perpendicular to the z-axis, and x = 0 at the intersection point, is the surface potential, z i is the axis perpendicular to the surface and passing through the molecule, where z = D is the position of the molecule, and z = 0 is on the surface, T is the temperature, e is the elementary charge, and k is the Boltzmann constant.

[0063] The surface electron density constant at the boundary is calculated by Equation (4).

[0064]

[0065] During the calculation process, the surface potential and the decay length (κ) are set as adjustment parameters, ε and ε 0 are the dielectric constants in the medium and in vacuum, e is the elementary charge, Z is the valence of the KCl electrolyte, n i∞ is the concentration of the KCl electrolyte, which is 1 mmol / L, and T is the temperature. F E is the electrostatic repulsion force.

[0066] The hydration force is calculated by Equation (5), and the magnitude of k represents the strength of the hydration force.

[0067]

[0068] F HB is the hydration force.

[0069] The calculated values using the DLVO theory are fitted to the long-range force between asphalt and aggregate, and the calculated values of the DLVO theory corresponding to the long-range force curve are obtained.

[0070] S5. Take the reference group asphalt mixture that has passed the inspection and meets the specification requirements, repeat the above steps S1 - S4, and obtain the measured and calculated values of their interaction forces as the AFM-interaction force standard value and the Zeta-force standard value.

[0071] Here, the measured value of the interaction force between Zhenhai No. 90 base asphalt and granite that meets the standard requirements is used as the AFM-interaction force standard value. This is because compared with other asphalts and aggregates, the adhesion between base asphalt and granite is the worst, and the water damage resistance is the worst.

[0072] Example 2

[0073] S1. Prepare a colloidal probe

[0074] S1.1. Attach silica to the end of the V-shaped tip cantilever beam of the atomic force microscope to obtain a pretreated probe, and the probe is placed for more than one day before use.

[0075] S1.2. Clean the tip with a plasma sputtering instrument for 10 minutes to remove possible contaminants on the probe, and obtain the cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It can be understood that the possible contaminants on the probe need to be removed before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0076] S1.3. Immerse the cleaned probe in a toluene solution of Zhenhai No. 90 base asphalt with a concentration of 10 mg / ml for 5 minutes, take it out and dry it to complete the modification step, and then calibrate the elastic constant of the modified probe using the Thermal Tune method to obtain a colloidal probe.

[0077] S2. Prepare a hydrophilic aggregate substrate:

[0078] Clean the basalt fragments with an area of 8 mm × 8 mm (length × width) in a Piranha solution at 90 °C for 30 minutes. Then rinse with ultrapure water and ethanol, treat in an ultrasonic cleaner for 30 minutes, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H2 O 2 It consists of. When using Piranha solution for cleaning, just submerge the aggregates.

[0079] S3. Use AFM to measure the adhesion force and long-range interaction force between asphalt and aggregates

[0080] Under the condition that the pH value of the aqueous solution is 2, the long-range interaction force and adhesion force between Zhenhai No. 90 base asphalt and basalt were measured.

[0081] Test the interaction between the probe (simulating sand particles) and asphalt inside the "O"-ring seal. When testing, inject an aqueous solution with a pH value of 2 to submerge the probe and the asphalt surface, and then conduct the test after standing for 30 min.

[0082] The tapping mode is adopted for testing. The maximum pressure applied during the testing process is 10 mN / m. Three asphalt surfaces are tested for each group of samples, and five points are tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that needs to be overcome when the probe detaches from the aggregate surface varies greatly, the statistical quantity for each group of samples is 100 groups during statistics. To reduce the influence of the probe size on the long-range interaction force and adhesion force, the test results are all divided by the radius of the probe ball. All tests are carried out at room temperature (25 °C).

[0083] S3. Use a Zeta potential analyzer to measure the surface potentials of the asphalt to be tested and the hydrophilic aggregates to be tested respectively.

[0084] Use a Zeta potential analyzer to measure the Zeta potentials of the asphalt droplets and aggregate particles.

[0085] The preparation process of the asphalt emulsion is as follows. First, suck 5 mL of asphalt-toluene solution (10 mg / mL) into a flat-bottom flask. Then place the flask in a dry and ventilated place and wait for the toluene to volatilize. Finally, add 30 mL of ultrapure water to the flask and ultrasonically treat it for 1 h to obtain the asphalt emulsion.

[0086] When preparing the aggregate particle suspension, select aggregate particles with a diameter of about 3 μm and prepare a suspension with a concentration of 0.1 g / mL.

[0087] For all samples, the Zeta potential test uses 1 mmol / L KCl as the background electrolyte, and the test is carried out at room temperature (25 °C). Five parallel tests are set for each type of aggregate, and each group of samples is tested 5 times, and the average value is taken as the final result.

[0088] S4. Use the surface potential to calculate the calculated value of the Zeta-force between the asphalt to be tested and the aggregate to be tested in the aqueous solution through the DLVO theory. The calculation method is the same as that in Example 1.

[0089] The calculated values using the DLVO theory are fitted to the long-range interaction force between asphalt and aggregates, and the calculated values of the DLVO theory corresponding to the long-range interaction force curve are obtained.

[0090] S5. Take the reference group asphalt mixture that has passed the inspection and meets the specification requirements, repeat the above steps S1 - S4, and obtain the measured and calculated values of their interaction forces as the AFM-interaction force standard value and the Zeta-force standard value.

[0091] Here, the measured value of the interaction force between Zhenhai No. 90 base asphalt and granite that meets the standard requirements is used as the AFM-interaction force standard value.

[0092] Example 3

[0093] S1. Prepare a colloidal probe

[0094] S1.1. Attach silica to the end of the V-shaped tip cantilever of the atomic force microscope to obtain a pretreated probe, and the probe is placed for more than one day before use.

[0095] S1.2. Clean the tip with a plasma sputtering instrument for 10 minutes to remove possible contaminants on the probe, and obtain the cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It can be understood that the possible contaminants on the probe need to be cleaned before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0096] S1.3. Immerse the cleaned probe in the toluene solution of Zhenhai No. 90 base asphalt for 5 minutes, take it out and dry it to complete the modification step, and then calibrate the elastic constant of the modified probe using the Thermal Tune method to obtain the colloidal probe.

[0097] S2. Prepare a hydrophilic aggregate substrate:

[0098] Clean the A-type limestone fragments with an area of 8 mm × 8 mm (length × width) in a Piranha solution at 90 °C for 30 minutes. Then rinse with ultrapure water and ethanol, treat in an ultrasonic cleaner for 30 minutes, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H 2 O 2 in a volume ratio of 7:3. When using the Piranha solution for cleaning, just submerge the aggregates.

[0099] S3. Use AFM to measure the adhesion force and long-range interaction force between asphalt and aggregates

[0100] Under the condition that the pH value of the aqueous solution is 2, the long-range force and adhesion force between Zhenhai No. 90 matrix asphalt with a concentration of 10 mg / ml and Class A limestone were tested.

[0101] The interaction between the probe (simulating sand particles) and the asphalt was tested inside the "O"-ring seal. During the test, an aqueous solution with a pH value of 2 was injected to submerge the probe and the asphalt surface, and the test was carried out after standing for 30 min.

[0102] The tapping mode was used for the test, and the maximum pressure applied during the test was 10 mN / m. Three asphalt surfaces were tested for each group of samples, and five points were tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that needs to be overcome when the probe detaches from the aggregate surface varies greatly, the statistical quantity for each group of samples was 100 groups during statistics. To reduce the influence of the probe size on the long-range force and adhesion force, the test results were divided by the radius of the probe ball. All tests were carried out at room temperature (25 °C).

[0103] S3. The surface potentials of the asphalt to be tested and the hydrophilic aggregate to be tested were measured respectively using a Zeta potential analyzer.

[0104] The Zeta potentials of the asphalt droplets and the aggregate particles were measured using a Zeta potential analyzer.

[0105] The preparation process of the asphalt emulsion is as follows. First, 5 mL of asphalt-toluene solution (10 mg / mL) was sucked into a flat-bottom flask. Then the flask was placed in a dry and ventilated place to wait for the toluene to volatilize. Finally, 30 mL of ultrapure water was added to the flask and ultrasonicated for 1 h to obtain the asphalt emulsion.

[0106] When preparing the aggregate particle suspension, aggregate particles with a diameter of about 3 μm were selected and prepared into a suspension with a concentration of 0.1 g / mL.

[0107] All Zeta potential tests of the samples were carried out using 1 mmol / L KCl as the background electrolyte, and the tests were all carried out at room temperature (25 °C). Five parallel tests were set for each type of aggregate, and each group of samples was tested 5 times, and the average value was taken as the final result.

[0108] S4. The calculated value of the Zeta-force between the asphalt to be tested and the aggregate to be tested in the aqueous solution was obtained by calculating using the DLVO theory through the surface potential, and the calculation method was the same as that in Example 1.

[0109] The calculated value of the DLVO theory was fitted with the long-range force between the asphalt and the aggregate. The calculated value of the DLVO theory corresponding to the long-range force curve was obtained.

[0110] S5. Take the reference group asphalt mixture whose extraction test meets the specification requirements, repeat the above steps S1 - S4, and obtain the measured and calculated values of their interaction forces as the AFM - interaction force standard value and the Zeta - interaction force standard value.

[0111] Here, the measured value of the interaction force between Zhenhai No. 90 base asphalt and granite that meets the standard requirements is used as the AFM - interaction force standard value.

[0112] Example 4

[0113] S1. Prepare a colloidal probe

[0114] S1.1. Attach silica to the end of the V - shaped tip cantilever beam of the atomic force microscope to obtain a pretreated probe, and the probe is placed for more than one day before use.

[0115] S1.2. Clean the tip with a plasma sputtering instrument for 10 min to remove possible contaminants on the probe, and obtain the cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It can be understood that the possible contaminants on the probe need to be removed before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0116] S1.3. Immerse the cleaned probe in a toluene solution of Zhenhai No. 90 base asphalt with a concentration of 10 mg / ml for 5 minutes, take it out and dry it to complete the modification step, and then calibrate the elastic constant of the modified probe using the Thermal Tune method to obtain the colloidal probe.

[0117] S2. Prepare a hydrophilic aggregate substrate:

[0118] Clean the B - type limestone fragments with an area of 8 mm × 8 mm (length × width) in a Piranha solution at 90 °C for 30 min. Then rinse with ultrapure water and ethanol, treat in an ultrasonic cleaner for 30 min, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H 2 O 2 in a volume ratio of 7:3. When using the Piranha solution for cleaning, just submerge the aggregates.

[0119] S3. Use AFM to measure the adhesion force and long - range interaction force between asphalt and aggregates

[0120] Under the condition that the pH value of the aqueous solution is 2, the long - range interaction force and adhesion force between Zhenhai No. 90 base asphalt and B - type limestone were measured.

[0121] The interaction between the test probe (simulating sand particles) and asphalt was tested inside the "O"-ring seal. During the test, an aqueous solution with a pH value of 2 was injected to submerge the probe and the asphalt surface, and the test was carried out after standing for 30 min.

[0122] The tapping mode was used for the test, and the maximum pressure applied during the test was 10 mN / m. Three asphalt surfaces were tested for each group of samples, and five points were tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that the probe needs to overcome when detaching from the aggregate surface varies greatly, the statistical quantity for each group of samples was 100 groups during statistics. To reduce the influence of the probe size on the long-range force and adhesion force, the test results were divided by the radius of the probe ball. All tests were carried out at room temperature (25 °C).

[0123] S3. The surface potentials of the asphalt to be tested and the hydrophilic aggregate to be tested were measured respectively using a Zeta potential analyzer.

[0124] The Zeta potentials of the asphalt droplets and aggregate particles were measured using a Zeta potential analyzer.

[0125] The preparation process of the asphalt emulsion is as follows. First, 5 mL of the asphalt-toluene solution (10 mg / mL) was sucked into a flat-bottom flask. Then the flask was placed in a dry and ventilated place to wait for the toluene to volatilize. Finally, 30 mL of ultrapure water was added to the flask and ultrasonicated for 1 h to obtain the asphalt emulsion.

[0126] When preparing the aggregate particle suspension, aggregate particles with a diameter of about 3 μm were selected and prepared into a suspension with a concentration of 0.1 g / mL.

[0127] For the Zeta potential test of all samples, 1 mmol / L KCl was used as the background electrolyte, and the tests were all carried out at room temperature (25 °C). Five parallel tests were set for each type of aggregate, and each group of samples was tested 5 times, and the average value was taken as the final result.

[0128] S4. The calculated value of the Zeta-force between the asphalt to be tested and the aggregate to be tested in the aqueous solution was obtained by calculating using the DLVO theory with the surface potential, and the calculation method was the same as that in Example 1.

[0129] The calculated value of the DLVO theory was fitted with the long-range force between the asphalt and the aggregate. The calculated value of the DLVO theory corresponding to the long-range force curve was obtained.

[0130] S5. The reference asphalt mixture that passed the inspection and met the specification requirements was taken, and the above steps S1 - S4 were repeated to obtain the measured value and calculated value of their interaction force as the AFM-interaction force standard value and the Zeta-force standard value.

[0131] Here, the measured value of the interaction force between Zhenhai No. 90 base asphalt and granite that meets the standard requirements is used as the AFM - interaction force standard value.

[0132] In the present invention, Zhenhai No. 90 base asphalt is used as the asphalt to be tested, and granite, basalt, Class A limestone, and Class B limestone are respectively used. By changing the pH value of the aqueous solution in step 3, the influence of the pH value on the water stability of the asphalt mixture is studied. As shown in Table 1.

[0133] Table 1 Examples of Zhenhai No. 90 base asphalt and aggregates at different pH values

[0134]

[0135] Example 21

[0136] S1. Preparation of colloidal probe

[0137] S1.1. Attach silica to the end of the V - type tip cantilever beam of the atomic force microscope to obtain a pretreated probe. The probe is placed for more than one day before use.

[0138] S1.2. Clean the tip with a plasma sputtering instrument for 10 min to remove possible contaminants on the probe, and obtain a cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It can be understood that the possible contaminants on the probe need to be cleaned before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0139] S1.3. Immerse the cleaned probe in an SBS modified asphalt toluene solution with a concentration of 10 mg / ml for 5 minutes, take it out and dry it to complete the modification step. Then, use the Thermal Tune method to calibrate the elastic constant of the modified probe to obtain a colloidal probe.

[0140] S2. Preparation of hydrophilic aggregate substrate:

[0141] Clean granite fragments with an area of 8 mm × 8 mm (length × width) in a Piranha solution at 90 °C for 30 min. Then rinse with ultrapure water and ethanol, treat in an ultrasonic cleaner for 30 min, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H 2 O 2 with a volume ratio of 7:3. When using the Piranha solution for cleaning, just submerge the aggregates.

[0142] S3. Use AFM to measure the adhesion force and long - range interaction force between asphalt and aggregates

[0143] Under the condition that the pH value of the aqueous solution is 2, the long-range force and adhesion between SBS modified asphalt and granite were tested.

[0144] The interaction between the probe (simulating sand particles) and asphalt was tested inside the "O" - ring seal. During the test, an aqueous solution with a pH value of 2 was injected to submerge the probe and the asphalt surface, and the test was carried out after standing for 30 min.

[0145] The tapping mode was used for the test. The maximum pressure applied during the test was 10 mN / m. Three asphalt surfaces were tested for each group of samples, and five points were tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that the probe needs to overcome when detaching from the aggregate surface varies greatly, the statistical quantity for each group of samples was 100 groups during statistics. To reduce the influence of the probe size on the long-range force and adhesion force, the test results were divided by the radius of the probe ball. All tests were carried out at room temperature (25 °C).

[0146] S3. The surface potentials of the asphalt to be tested and the hydrophilic aggregate to be tested were measured respectively using a Zeta potential analyzer.

[0147] The Zeta potentials of the asphalt droplets and aggregate particles were measured using a Zeta potential analyzer.

[0148] The preparation process of the asphalt emulsion is as follows. First, 5 mL of asphalt - toluene solution (10 mg / mL) was sucked into a flat-bottom flask. Then the flask was placed in a dry and ventilated place to wait for the toluene to volatilize. Finally, 30 mL of ultrapure water was added to the flask and ultrasonicated for 1 h to obtain the asphalt emulsion.

[0149] When preparing the aggregate particle suspension, aggregate particles with a diameter of about 3 μm were selected and prepared into a suspension with a concentration of 0.1 g / mL.

[0150] For all samples, the Zeta potential tests were carried out using 1 mmol / L KCl as the background electrolyte, and the tests were all carried out at room temperature (25 °C). Five parallel tests were set for each type of aggregate, and each group of samples was tested 5 times, and the average value was taken as the final result.

[0151] S4. The calculated value of the Zeta - force between the asphalt to be tested and the aggregate to be tested in the aqueous solution was obtained by calculating using the DLVO theory through the surface potential. The calculation method was the same as that in Example 1.

[0152] The calculated value of the DLVO theory was fitted with the long-range force between the asphalt - aggregate. The calculated value of the DLVO theory corresponding to the long-range force curve was obtained.

[0153] S5. Take the reference group asphalt mixture whose extraction test meets the specification requirements, repeat the above steps S1 - S4, and obtain the measured and calculated values of their interaction forces as the AFM - interaction force standard value and the Zeta - interaction force standard value.

[0154] Here, the measured value of the interaction force between Zhenhai No. 90 base asphalt and granite that meets the standard requirements is used as the AFM - interaction force standard value.

[0155] Example 22

[0156] S1. Prepare a colloidal probe

[0157] S1.1. Attach silica to the end of the V - type tip cantilever beam of the atomic force microscope to obtain a pretreated probe, and the probe is placed for more than one day before use.

[0158] S1.2. Clean the tip with a plasma sputtering instrument for 10 min to remove possible contaminants on the probe, and obtain the cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It can be understood that the possible contaminants on the probe need to be cleaned before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0159] S1.3. Immerse the cleaned probe in an SBS - modified asphalt toluene solution with a concentration of 10 mg / ml for 5 minutes, take it out and dry it to complete the modification step, and then calibrate the elastic constant of the modified probe using the Thermal Tune method to obtain the colloidal probe.

[0160] S2. Prepare a hydrophilic aggregate substrate:

[0161] Clean basalt fragments with an area of 8 mm × 8 mm (length × width) in a Piranha solution at 90 °C for 30 min. Then rinse with ultrapure water and ethanol, process in an ultrasonic cleaner for 30 min, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H 2 O 2 in a volume ratio of 7:3. When using the Piranha solution for cleaning, the aggregate only needs to be submerged.

[0162] S3. Use AFM to measure the adhesion force and long - range interaction force between asphalt and aggregate

[0163] Under the condition that the pH value of the aqueous solution is 2, the long - range interaction force and adhesion force between SBS - modified asphalt and basalt were measured.

[0164] The interaction between the test probe (simulating sand particles) and asphalt was tested inside an "O"-ring seal. During the test, an aqueous solution with a pH value of 2 was injected to submerge the probe and the asphalt surface, and the test was carried out after standing for 30 min.

[0165] The tapping mode was used for the test, and the maximum pressure applied during the test was 10 mN / m. Three asphalt surfaces were tested for each group of samples, and five points were tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that needs to be overcome when the probe detaches from the aggregate surface varies greatly, the statistical quantity for each group of samples was 100 groups during statistics. To reduce the influence of the probe size on the long-range force and adhesion force, the test results were divided by the radius of the probe ball. All tests were carried out at room temperature (25 °C).

[0166] S3. The surface potentials of the asphalt to be tested and the hydrophilic aggregate to be tested were measured separately using a Zeta potential analyzer.

[0167] The Zeta potentials of the asphalt droplets and aggregate particles were measured using a Zeta potential analyzer.

[0168] The preparation process of the asphalt emulsion is as follows. First, 5 mL of an asphalt-toluene solution (10 mg / mL) was sucked into a flat-bottom flask. Then the flask was placed in a dry and ventilated place to wait for the toluene to volatilize. Finally, 30 mL of ultrapure water was added to the flask and ultrasonicated for 1 h to obtain the asphalt emulsion.

[0169] When preparing the aggregate particle suspension, aggregate particles with a diameter of about 3 μm were selected and prepared into a suspension with a concentration of 0.1 g / mL.

[0170] For the Zeta potential test of all samples, 1 mmol / L KCl was used as the background electrolyte, and the test was carried out at room temperature (25 °C). Five parallel tests were set for each type of aggregate, and each group of samples was tested 5 times, and the average value was taken as the final result.

[0171] S4. The calculated value of the Zeta-force between the asphalt to be tested and the aggregate to be tested in the aqueous solution was obtained by calculating using the DLVO theory through the surface potential, and the calculation method was the same as that in Example 1.

[0172] The calculated value of the DLVO theory was fitted with the long-range force between the asphalt and the aggregate to obtain the calculated value of the DLVO theory corresponding to the long-range force curve.

[0173] S5. The reference asphalt mixture that met the specification requirements was taken, and the above steps S1-S4 were repeated to obtain the measured value and calculated value of their interaction force as the AFM-interaction force standard value and the Zeta-force standard value.

[0174] Here, the measured value of the interaction force between Zhenhai No. 90 matrix asphalt and granite that meets the standard requirements is used as the AFM - interaction force standard value.

[0175] Example 23

[0176] S1. Prepare a colloidal probe

[0177] S1.1. Attach silica to the end of the V - shaped tip cantilever beam of an atomic force microscope to obtain a pretreated probe. The probe is placed for more than one day before use.

[0178] S1.2. Clean the tip with a plasma sputtering instrument for 10 min to remove possible contaminants on the probe, and obtain a cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It can be understood that the possible contaminants on the probe need to be cleaned before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0179] S1.3. Immerse the cleaned probe in an SBS - modified asphalt toluene solution with a concentration of 10 mg / ml for 5 minutes, take it out and dry it to complete the modification step. Then, calibrate the elastic constant of the modified probe using the Thermal Tune method to obtain a colloidal probe.

[0180] S2. Prepare a hydrophilic aggregate substrate:

[0181] Clean A - type limestone fragments with an area of 8 mm×8 mm (length×width) in a Piranha solution at 90 °C for 30 min. Then rinse with ultrapure water and ethanol, treat in an ultrasonic cleaner for 30 min, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H 2 O 2 in a volume ratio of 7:3. When using the Piranha solution for cleaning, the aggregate can be submerged.

[0182] S3. Use AFM to measure the adhesion force and long - range interaction force between asphalt and aggregate

[0183] Under the condition that the pH value of the aqueous solution is 2, the long - range interaction force and adhesion force between SBS - modified asphalt and A - type limestone are measured.

[0184] Test the interaction between the probe (simulating sand grains) and asphalt within an "O" - ring seal. When testing, inject an aqueous solution with a pH value of 2 to submerge the probe and the asphalt surface, and perform the test after standing for 30 min.

[0185] The test was carried out in tapping mode, and the maximum pressure applied during the test was 10 mN / m. Three asphalt surfaces were tested for each group of samples, and five points were tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that needs to be overcome when the probe detaches from the aggregate surface varies greatly, the statistical quantity for each group of samples was 100 groups during statistics. In order to reduce the influence of the probe size on the long-range force and adhesion force, the test results were all divided by the radius of the probe ball. All tests were carried out at room temperature (25 °C).

[0186] S3. Use a Zeta potential analyzer to measure the surface potentials of the asphalt to be tested and the hydrophilic aggregate to be tested respectively.

[0187] Use a Zeta potential analyzer to measure the Zeta potentials of the asphalt droplet and the aggregate particle surface.

[0188] The preparation process of the asphalt emulsion is as follows. First, suck 5 mL of asphalt-toluene solution (10 mg / mL) into a flat-bottom flask. Then place the flask in a dry and ventilated place and wait for the toluene to volatilize. Finally, add 30 mL of ultrapure water to the flask and ultrasonically treat it for 1 h to obtain the asphalt emulsion.

[0189] When preparing the aggregate particle suspension, select aggregate particles with a diameter of about 3 μm and prepare a suspension with a concentration of 0.1 g / mL.

[0190] For the Zeta potential test of all samples, 1 mmol / L KCl was used as the background electrolyte, and the tests were all carried out at room temperature (25 °C). Five parallel tests were set for each type of aggregate, and each group of samples was tested 5 times, and the average value was taken as the final result.

[0191] S4. Use the surface potential to calculate the calculated value of the Zeta-force between the asphalt to be tested and the aggregate to be tested in the aqueous solution through the DLVO theory, and the calculation method is the same as that in Example 1.

[0192] Fit the calculated value of the DLVO theory with the long-range force between the asphalt and the aggregate. Obtain the calculated value of the DLVO theory corresponding to the long-range force curve.

[0193] S5. Take the reference group asphalt mixture that has been tested and meets the specification requirements, repeat the above steps S1-S4, and obtain the measured value and calculated value of the interaction force between them as the AFM-interaction force standard value and the Zeta-force standard value.

[0194] Here, the measured value of the interaction force between Zhenhai No. 90 matrix asphalt and granite that meets the standard requirements is used as the AFM-interaction force standard value.

[0195] Example 24

[0196] S1. Prepare a colloidal probe

[0197] S1.1. Attach silica to the end of the V-shaped tip cantilever of an atomic force microscope to obtain a pretreated probe, and place the probe for more than one day before use.

[0198] S1.2. Clean the tip with a plasma sputtering instrument for 10 min to remove possible contaminants on the probe and obtain a cleaned probe. The purpose of this step is to make the pretreated probe hydrophilic. It should be understood that the possible contaminants on the probe need to be removed before each test. The adhesion thickness of silica is 3 nm - 5 nm.

[0199] S1.3. Immerse the cleaned probe in a toluene solution of SBS modified asphalt with a concentration of 10 mg / ml for 5 minutes, take it out and dry it to complete the modification step, and then calibrate the elastic constant of the modified probe by the Thermal Tune method to obtain a colloidal probe.

[0200] S2. Prepare a hydrophilic aggregate substrate:

[0201] Clean a Class B limestone fragment with an area of 8 mm × 8 mm (length × width) in a Piranha solution at 90 °C for 30 min. Then rinse with ultrapure water and ethanol, treat in an ultrasonic cleaner for 30 min, then rinse with ultrapure water, and dry with ultrapure nitrogen to obtain a hydrophilic aggregate substrate. The Piranha solution is composed of H 2 SO 4 and H 2 O 2 in a volume ratio of 7:3. When cleaning with the Piranha solution, just submerge the aggregate.

[0202] S3. Use AFM to test the adhesion force and long-range interaction force between asphalt and aggregate

[0203] Under the condition that the pH value of the aqueous solution is 2, the long-range interaction force and adhesion force between SBS modified asphalt and Class B limestone are tested.

[0204] Test the interaction between the probe (simulating sand particles) and asphalt in an "O"-ring seal. When testing, inject an aqueous solution with a pH value of 2 to submerge the probe and the asphalt surface, and let it stand for 30 min before testing.

[0205] The tapping mode is used for testing, and the maximum pressure applied during the testing process is 10 mN / m. Each group of samples is tested on 3 asphalt surfaces, and 5 points are tested on each asphalt surface. When analyzing the adhesion force, since the adhesion force that needs to be overcome when the probe detaches from the aggregate surface varies greatly, the statistical quantity for each group of samples is 100 groups during statistics. To reduce the influence of the probe size on the long-range interaction force and adhesion force, all test results are divided by the radius of the probe sphere. All tests are carried out at room temperature (25 °C).

[0206] S3. Use a Zeta potential analyzer to measure the surface potentials of the asphalt to be tested and the hydrophilic aggregate to be tested respectively.

[0207] Use a Zeta potential analyzer to measure the Zeta potentials on the surfaces of asphalt droplets and aggregate particles.

[0208] The preparation process of the asphalt emulsion is as follows. First, suck 5 mL of asphalt-toluene solution (10 mg / mL) into a flat-bottom flask. Then place the flask in a dry and well-ventilated place and wait for the toluene to evaporate. Finally, add 30 mL of ultrapure water to the flask and perform ultrasonic treatment for 1 h to obtain the asphalt emulsion.

[0209] When preparing the aggregate particle suspension, select aggregate particles with a diameter of about 3 μm and prepare a suspension with a concentration of 0.1 g / mL.

[0210] For the Zeta potential tests of all samples, 1 mmol / L KCl is used as the background electrolyte, and the tests are all carried out at room temperature (25 °C). Five parallel tests are set for each type of aggregate, and each group of samples is tested 5 times, and the average value is taken as the final result.

[0211] S4. Use the surface potential to calculate the calculated value of the Zeta-force between the asphalt to be tested and the aggregate to be tested in the aqueous solution through the DLVO theory. The calculation method is the same as that in Example 1.

[0212] Fit the calculated value by the DLVO theory with the long-range force between the asphalt and the aggregate to obtain the calculated value by the DLVO theory corresponding to the long-range force curve.

[0213] S5. Take the reference asphalt mixture that has been detected to meet the specification requirements, repeat the above steps S1-S4, and obtain the measured value and calculated value of their mutual force as the AFM-mutual force standard value and the Zeta-force standard value.

[0214] Here, the measured value of the mutual force between Zhenhai No. 90 base asphalt and granite that meets the standard requirements is used as the AFM-mutual force standard value.

[0215] In this invention, SBS modified asphalt is used as the asphalt to be tested, and granite, basalt, Class A limestone and Class B limestone are used respectively. By changing the pH value of the aqueous solution in Step 3, the influence of the pH value on the water stability of the asphalt mixture is studied. As shown in Table 2. It should be noted that in Examples 45 to 48, the pH value of the aqueous solution is not adjusted, that is, the pH value of water is 7.

[0216] Table 2 Examples of SBS modified asphalt and aggregates at different pH values

[0217]

[0218] The influence of pH value on the water stability of asphalt mixtures was studied through Examples 1 - 40 of the present invention below.

[0219] The test results of the long - range forces and adhesion forces between Zhenhai No. 90 base asphalt and SBS modified asphalt and basalt, granite, Class A limestone and Class B limestone are as Figure 1 and Figure 2 shown.

[0220] Figure 1 In (a) of, when the pH value is 2, the long - range force between Zhenhai No. 90 base asphalt and aggregates. The long - range forces are sorted from large to small as granite, basalt, Class B limestone, Class A limestone, and all the long - range forces are repulsive forces. The corresponding adhesion force ranking is opposite to the long - range force. As shown in (f) of Figure 1 , it is sorted from large to small as Class A limestone, Class B limestone, basalt, granite. The greater the adhesion force between asphalt and aggregates, the better the water stability, and the smaller the repulsive force between the corresponding base asphalt and aggregates will be. Figure 1 In (b) of, when the pH value is 4, the repulsive forces between basalt, Class A limestone and Class B limestone and the base asphalt increase, and the adhesion forces also decrease accordingly. The decrease amplitude of Class B limestone is the largest, and the adhesion force decreases from 2.5 mN / m at pH = 2 to 0.8 mN / m. However, the long - range force between granite and the base asphalt changes from repulsive force to strong attractive force, and the adhesion force also shows a large increase, reaching 5.2 mN / m. Figure 1 In (c) of, when the pH value is 6, the long - range force between granite and the base asphalt turns into a repulsive force, and the adhesion force also decreases to 0.6 mN / m. At this time, the long - range forces between basalt, Class A limestone and Class B limestone and the base asphalt are all attractive forces, and their magnitudes are almost the same, and the adhesion forces also increase to about 4 mN / m, as shown in (f) of Figure 1 . Figure 1 In (d) and (e) of, when the pH increases to 8 and 10, the long - range forces between the four kinds of aggregates and the base asphalt are all repulsive forces. The long - range forces are sorted from large to small as granite, basalt, Class B limestone, Class A limestone, which is the same as when the pH is 2. The adhesion forces are also all close to 0 mN / m. However, the long - range force at pH = 10 is less than that at pH = 8, and the adhesion force increases slightly but is still very weak. It can be considered that the adhesion between aggregates and the base asphalt at pH = 10 is better than that at pH = 8. Generally speaking, the adhesion between aggregates and the base asphalt under alkaline conditions is greatly weakened, which is not conducive to the prevention of water damage.

[0221] As Figure 2As shown, the variation trend of the long-range force between SBS modified asphalt and the surfaces of various aggregates is basically the same as that between matrix asphalt and aggregate surfaces. However, at the same pH value, the long-range force is smaller than that of matrix asphalt, and the adhesion force increases, indicating that SBS modified asphalt is less likely to desorb from the aggregate surface. Figure 2 In (a) of Figure 2 , when the pH value is 2, the adhesion force between SBS modified asphalt and four kinds of aggregates can reach more than 3.7 mN / m. Figure 2 In (b) and (c) of Figure 2 , when the pH is 4 and 6, the adhesion force between SBS modified asphalt and basalt and A and B types of limestone is about 2.5 mN / m, while the adhesion force between granite and SBS modified asphalt decreases from 3.5 mN / m at pH 4 to 1.0 mN / m at pH 6. Figure 2 In (d) and (e) of Figure 2 , when the pH rises to 8 and 10, the adhesion force between SBS modified asphalt and the four kinds of aggregates is very weak. Compare the forces between matrix asphalt and SBS modified asphalt and the four kinds of aggregates respectively. At pH values of 2 and 4, except that the adhesion force between granite and matrix asphalt is greater than that of SBS modified asphalt at pH 4, the adhesion force between SBS modified asphalt and aggregates is greater than that of matrix asphalt under other conditions, and they are similar at pH 6. Although the adhesion force between the two kinds of asphalt and aggregates is very weak at pH 8 and 10, it can still be observed that the adhesion of SBS modified asphalt to aggregates is greater. It is proved that compared with matrix asphalt, SBS modified asphalt has better water stability with aggregates, and thus it can be inferred that its water damage resistance ability is more excellent.

[0222] The test results of the Zeta potential values of asphalt and aggregate surfaces in step 3 of the example are shown in Table 3.

[0223] Table 3 Zeta potential values of asphalt droplets and aggregate particle surfaces

[0224] The calculated values by the DLVO theory are fitted with the long-range force between asphalt and aggregates. Figure 1 and Figure 2Each force curve corresponds to a corresponding solid line, which is the calculated value of the DLVO theory corresponding to the long-range force curve. From the above results, it can be seen that each long-range force curve can be fitted with the fitting curve, indicating that the obtained long-range force is basically consistent with the calculated value of the DLVO theory. By observing the changes in the long-range force curve and the surface potential value, it can be found that the change in the long-range force under different pH environments can be explained by the electrostatic force between asphalt and aggregates. When the pH value is 2, the Zeta potential values of asphalt and the surfaces of the four aggregates are all positive, so the long-range force between them shows repulsion. As the pH value increases to 4, the Zeta potential values of two kinds of asphalt and the surfaces of the remaining three aggregates except granite are all positive, and the Zeta potential value of the granite surface turns negative. Even if the negative value is very small, it still leads to the adsorption between asphalt and aggregates, which also explains that the long-range force between asphalt and granite changes from negative to positive under this condition, and the adhesion between asphalt and granite is better at this time. The change in the long-range force between basalt and two kinds of limestone and asphalt when the solution pH is 6 can also be proved by different surface potential values. The main reason for this phenomenon is due to the change in the Zeta potential value of the asphalt and aggregate surfaces. Observing the experimental results, it can be found that the Zeta potential value of the asphalt and aggregate surfaces generally shows a decreasing trend as the pH increases. From Figure 1 and Figure 2 it can be seen that the adhesion force between limestone and asphalt in aqueous solution is the largest and the adhesion performance is the best, while the adhesion between granite and asphalt is the worst. The SBS modified asphalt has better adhesion with aggregates than the base asphalt and better resistance to water damage performance. Compared with the acidic environment, the alkaline environment is more unfavorable to the adhesion between asphalt and aggregates in aqueous solution.

[0225] Here, the measured value of the interaction force between Zhenhai No. 90 base asphalt and granite that meets the standard requirements is used as the AFM - interaction force standard value. By comparing the AFM - interaction force test values of the asphalt to be tested and the aggregates to be tested with the AFM - interaction force standard value, and the calculated value of the Zeta - force between the asphalt to be tested and the hydrophilic aggregates to be tested in aqueous solution with the Zeta - force standard value, the water stability of the asphalt mixture is evaluated.

[0226] If the AFM - interaction force test values of the asphalt to be tested and the hydrophilic aggregates to be tested, and the calculated value of the Zeta - force between the asphalt to be tested and the hydrophilic aggregates to be tested in aqueous solution are greater than the Zeta - force standard value, it indicates that the water stability of the asphalt mixture meets the requirements.

[0227] The AFM-interaction force test values and AFM-interaction force standard values of the asphalt to be tested and the hydrophilic aggregate to be tested, as well as the calculated Zeta-force value between the asphalt to be tested and the hydrophilic aggregate to be tested in the aqueous solution are less than the Zeta-force standard value, indicating that the water stability of the asphalt mixture does not meet the requirements.

[0228] According to the test results of the embodiments of the present invention, the standard values of the long-range force, adhesion force and DLVO calculated value at different pH values are as follows:

[0229] When pH = 2, the adhesion force test value is greater than or equal to 1.70 mN / m, the long-range force test value is less than or equal to 0.30 mN / m, and the calculated Zeta-force value is less than 0.30 mN / m; when pH = 4, the adhesion force test value is greater than or equal to 0.82 mN / m, the long-range force test value is less than or equal to 0.72 mN / m, and the calculated Zeta-force value is less than 0.75 mN / m; when pH = 6, the adhesion force test value is greater than or equal to 0.60 mN / m, the long-range force test value is less than or equal to 0.33 mN / m, and the calculated Zeta-force value is less than 0.31 mN / m; when pH = 8, the adhesion force test value is greater than or equal to 0 mN / m, the long-range force test value is less than or equal to 1.37 mN / m, and the calculated Zeta-force value is less than 1.46 mN / m; when pH = 10, the adhesion force test value is greater than or equal to 0 mN / m, the long-range force test value is less than or equal to 0.88 mN / m, and the calculated Zeta-force value is less than 0.88 mN / m. The long-range force and the DLVO calculated value are taken at the value when the separation distance between the probe and the substrate is 10 nm.

[0230] By comparison, when pH = 4, the measured values and calculated values of the No. 90 base asphalt and SBS modified asphalt with basalt and two types of limestone are less than the standard values, and the water stability performance is unqualified. When pH = 2, 6, 8, 10, the measured values and calculated values of the No. 90 base asphalt and SBS modified asphalt with basalt and two types of limestone are greater than the standard values, indicating that the asphalt mixture to be evaluated meets the requirements.

[0231] Comparative Example 1

[0232] The adhesion performance between asphalt and aggregate in different acidic and alkaline environments was evaluated by the boiling water method. The boiling water method test was carried out according to the implementation process of T0616-1993 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). In the test, four kinds of aggregates were selected for evaluation, namely Class A limestone, Class B limestone, granite and basalt.

[0233] The main purpose of the test is to classify the adhesion grade between asphalt and aggregates by observing the degree of asphalt stripping from the aggregate surface. The specific evaluation criteria for the adhesion grade are shown in Table 4. During the test, SBS modified asphalt and four types of aggregates in the 13.2 mm size range were selected as raw materials. For each type of stone, samples with similar mass, regular and neat shape, and close to cube shape were cleaned and dried thoroughly for evaluation. The stripping situation between SBS modified asphalt and aggregates was visually observed through the boiling water test to reflect the adhesion performance, and the AFM test results were verified.

[0234] According to the technical requirements for aggregate adhesion in the domestic industry standard "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40 - 2004), the adhesion grade is required to be above Grade III on all grades of roads in each rainfall zone. Aggregates with an adhesion grade of III can be used in the semi - arid and arid climate regions, but cannot be used in the humid and wet regions.

[0235] Table 4 Evaluation Criteria for Adhesion Grade between Asphalt and Aggregates

[0236] Peeling condition of asphalt film on aggregate surface Adhesion grade The asphalt film is intact, without peeling or slightly peeling at the edges and corners Grade V The asphalt film is slightly driven by water, and the exposed area of aggregate peeling is less than 10% Grade IV A small part of the asphalt film is driven by water, and the exposed area of aggregate peeling is less than 30% Grade III Most of the asphalt film is driven by water, and the exposed area of aggregate peeling is greater than 30% Grade II The asphalt film is completely driven by water, floating on the water surface, and the aggregate is completely exposed Grade I

[0237] The determination results of the adhesion between Zhenhai No. 90 base asphalt and aggregates after boiling water are shown in Table 5. After boiling in aqueous solutions with pH values of 2, 4, and 6, only a small part of the asphalt on the granite surface peeled off at the edges and corners, but not more than 10%, and the adhesion grade was evaluated as Grade IV. When the pH increased to 8 and 10, it was obvious that the granite surface was exposed, indicating that part of the asphalt film was carried away by water, forming water damage. At this time, the adhesion grade between granite and asphalt was evaluated as Grade III. After boiling in aqueous solutions with pH values of 2, 4, and 6, the asphalt film on basalt remained intact, and the adhesion grade was evaluated as Grade III. At pH values of 8 and 10, there was asphalt peeling at the edges and corners of basalt, and the peeling area was larger at pH = 10 but did not exceed 10%. Therefore, the adhesion grade between basalt and asphalt at pH values of 8 and 10 was Grade IV. It can be seen that alkaline conditions will promote the stripping of asphalt from the aggregate surface and deteriorate its water damage resistance. By comparison, it can be found that the water damage resistance of basalt is significantly better than that of granite. As an alkaline oxide, limestone has an intact asphalt film at each pH value, indicating its good water damage resistance.

[0238] Table 5 Adhesion Grades between Asphalt and Four Types of Aggregates

[0239] The determination results of the adhesion strength between SBS modified asphalt and aggregates are shown in Table 6. When the pH is 2, 6, or 8, there is obvious peeling of the asphalt film on the granite surface, but the peeling rate does not exceed 10%, and the adhesion is evaluated as Grade IV. When the pH is 4, only the edges and corners of the granite surface have slight peeling of the asphalt film. At this time, the adhesion of the granite is evaluated as Grade V, and the improvement of the adhesion may be related to the strong adsorption force between the granite and SBS asphalt under this condition. When the pH is 10, the peeling of the asphalt film on the granite surface is relatively serious, and the aggregates are exposed, and the adhesion is evaluated as Grade III. Compared with granite, basalt, Class A limestone, and Class B limestone have better adhesion with SBS modified asphalt. Except for the slight peeling of basalt when the pH is 8 (the adhesion grade is Grade IV), the asphalt film can completely cover the aggregate surface under other conditions (the adhesion grade is Grade V). The test results show that the order of the adhesion of aggregates to SBS modified asphalt from large to small is: limestone, basalt, granite. The increase in the solution pH value will weaken the adhesion force between the aggregate and SBS modified asphalt. Comparing the boiling water test results with the interaction force test results, it is found that the two have good correlation. It shows that the water stability of asphalt mixtures can be effectively evaluated according to the evaluation method of the present invention.

[0240] Table 6 Evaluation results of the adhesion between SBS modified asphalt and aggregates in aqueous solutions with different acid-base properties

[0241]

[0242]

[0243] The boiling water test shows that the water stability of the mixture is better. However, in the test results of the method of the present invention, the adhesion between granite and matrix asphalt is the worst, which is Grade III. According to the technical requirements for the adhesion of aggregates in the domestic industry standard "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004), the adhesion grade is required to be above Grade III on all grades of roads in each rainfall zone. Granite with an adhesion grade of Grade III can be used in the semi-arid and arid climate regions, but it cannot be used in the humid and wet regions. Due to the low adhesion grade between asphalt and granite, the application area of granite is restricted to a certain extent. Then, the results of screening granite and matrix asphalt obtained according to the test results of the present invention do not meet the usage requirements. The water stability performance of the mixture can be evaluated more strictly according to the method of the present invention, and the detection range and detection efficiency can be significantly improved.

[0244] In summary, the present invention provides an innovative rapid evaluation method for the water stability of asphalt mixtures. This method uses the AFM colloidal probe technique to test the water stability of asphalt and aggregates, without the need for preparing mixture specimens, and can quickly and accurately evaluate the water stability of asphalt mixtures within two hours. This technique measures the interaction force between asphalt and aggregates at the microscale, provides high-precision test data, and accurately evaluates their water stability. Combining the Zeta potential test and the calculation and analysis of the DLVO theory, this method can quantitatively evaluate the stability of the asphalt-aggregate system under different pH values and salt solution conditions, and effectively predict its water stability. In particular, it can simulate the water damage effects that acid rain areas, coastal areas, or saline-alkali lands may have on asphalt pavements, providing a scientific basis for the optimal design and durability of road materials.

[0245] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0246] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A method for evaluating water stability of asphalt mixture, characterized in that: The following steps are involved: The silica is adhered to the tip of an atomic force microscope, and modified and calibrated with the asphalt to be tested to obtain a colloidal probe; the aggregate to be tested is subjected to a hydrophilic treatment to prepare a hydrophilic aggregate substrate; In the tapping mode of atomic force microscope, the hydrophilic aggregate substrate was tested using a colloidal probe to obtain the AFM-interaction force test value between the tested asphalt and the tested aggregate; The surface Zeta potential test values ​​of the asphalt to be tested and the aggregate to be tested are used to perform DLVO theoretical calculations to obtain the calculated Zeta-force between the asphalt to be tested and the aggregate to be tested; Referring to the above method, the standard asphalt and the standard aggregate in the asphalt mixture standard specimen are tested to obtain the standard value of the AFM-interaction force and the standard value of the Zeta-force between the standard asphalt and the standard aggregate; Comparing the AFM-interaction force test value with the AFM-interaction force standard value, as well as the Zeta-force calculation value with the Zeta-force standard value, when the following conditions are met, the water stability of the asphalt mixture meets the use requirements; The AFM-interaction force test value of the asphalt to be tested and the aggregate to be tested is ≥ the AFM-interaction force standard value between the standard asphalt and the standard aggregate, and the Zeta-force calculated value between the asphalt to be tested and the hydrophilic aggregate to be tested is ≥ the Zeta-force standard value between the standard asphalt and the standard aggregate.

2. The method for evaluating water stability of asphalt mixture according to claim 1, characterized in that: The adhesion thickness of silicon dioxide is 3nm-5nm.

3. The method for evaluating water stability of asphalt mixture according to claim 1, characterized in that: The method for modifying the pretreatment probe with the asphalt to be tested is as follows: dispersing the asphalt to be tested in toluene to prepare an asphalt solution; and immersing the pretreatment probe in the asphalt solution.

4. The method for evaluating water stability of asphalt mixture according to claim 1, characterized in that: The concentration of the asphalt solution is 10 mg / ml to 15 mg / ml.

5. The method for evaluating water stability of asphalt mixture according to claim 3, characterized in that: The soaking time is 5min to 7min.

6. The method for evaluating water stability of asphalt mixture according to claim 1, characterized in that: The hydrophilic treatment is carried out in a mixed solution of sulfuric acid and hydrogen peroxide at 90°C to 95°C for 30min to 35min.

7. The method for evaluating water stability of asphalt mixture according to claim 6, characterized in that: In the mixed solution of sulfuric acid and hydrogen peroxide, the volume percentage of sulfuric acid is 70% to 75%, and the rest is hydrogen peroxide, which is 100% in total.

8. The method for evaluating water stability of asphalt mixture according to claim 1, characterized in that: When the hydrophilic aggregate substrate was tested using a colloidal probe, the applied pressure was 10 mN / m.

9. The method for evaluating water stability of asphalt mixture according to claim 1, characterized in that: The asphalt mixture standard specimen is a mixture specimen that meets the adhesion test and water stability test standards.

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