A quantitative evaluation method for asphalt-aggregate adhesion properties

Abstract

This invention discloses a quantitative evaluation method for the adhesion performance of asphalt and aggregate, comprising the following steps: S1, placing the aggregate coated with asphalt in a dye solution and heating it using a boiling or immersion method; S2, testing the reacted dye solution using photoelectric colorimetry to obtain an absorption spectrum, where the peak height is h and the half-peak width is a; wherein the peak height index δ is the ratio of peak height h to half-peak width a, and the peak area index γ is the ratio of peak area s to half-peak width a. The adhesion performance between aged asphalt and aggregate is evaluated based on the peak height index δ or the peak area index γ. This invention quantitatively calculates the degree of asphalt stripping after boiling aged asphalt and aggregate, providing simple and effective guidance for the selection of asphalt and aggregate types in asphalt mixture design, and offering scientific evaluation indicators and optimal maintenance timing for preventive maintenance.

Description

Technical Field

[0001] This invention is a quantitative evaluation method for asphalt-aggregate adhesion performance, belonging to the technical field of road asphalt pavement durability. Background Technology

[0002] Asphalt aging causes it to harden, reduces its adhesion, and makes asphalt pavements prone to cracking, thus affecting road service life. Utilizing scientific and effective methods to predict the degree of asphalt pavement aging and the adhesion between asphalt and aggregates is beneficial for making better maintenance decisions and developing corresponding maintenance plans, thereby improving the durability of asphalt pavements. Currently, the degree of asphalt aging is predicted holistically through routine experiments on asphalt and asphalt mixtures. The degree of aging is preliminarily judged by analyzing conventional indicators of aged asphalt, such as residual penetration, ductility, and softening point, or by analyzing the attenuation of certain indicators such as infrared spectroscopy and rheological properties to roughly predict the service life of asphalt pavements. However, qualitative or semi-quantitative descriptions of the asphalt aging state cannot effectively and accurately quantify the aging process of asphalt mixtures; therefore, developing new quantitative evaluation index systems is crucial.

[0003] The strength of the adhesion between asphalt and aggregate is a crucial factor affecting the water stability of asphalt pavements. Domestic and international research commonly employs methods such as the boiling water method, water immersion method, photoelectric colorimetry, and SHRP net adsorption method to qualitatively or semi-quantitatively evaluate the adhesion performance between asphalt and aggregate. Each method has its advantages and disadvantages. The boiling water method and water immersion method are commonly used evaluation methods in engineering practice. These two methods are simple and rapid to operate and can qualitatively and semi-quantitatively evaluate the adhesion between asphalt and aggregate, but they are susceptible to subjective human factors. The photoelectric colorimetry method can quantitatively assess adhesion force using the absorbance principle, reflecting the degree of asphalt stripping on the aggregate surface. It provides a quantitative evaluation and analysis of the adhesion performance between asphalt and aggregate based on the water immersion method.

[0004] To enable quantitative and accurate evaluation of the interfacial adhesion between asphalt and aggregate using the boiling water and immersion water methods, patent "A Calculation Method for Asphalt-Aggregate Stripping Rate in Asphalt Pavement" (CN109596456A) employs a water damage sensitivity tester to simulate real water damage to the pavement. It quantitatively calculates the stripping rate of asphalt and aggregate at different service years using the boiling water method. However, this method considers numerous influencing factors and is quite complex. Patent "An Improved Method for Testing the Adhesion of Asphalt to Coarse Aggregate using the Boiling Water Method" (CN109211717A) utilizes ultrasonic testing and warm water treatment to simulate real-world conditions. It uses the reduction in asphalt mass to reflect the degree of stripping, abandoning the method of evaluating adhesion based on stripping area. This method wets the aggregate surface before it coats the asphalt, and the surface moisture can affect the adhesion between asphalt and aggregate, leading to significant errors.

[0005] Photoelectric colorimetry offers advantages such as high precision, good reproducibility, and ease of operation, overcoming the limitations of the boiling water method. It has certain advantages in quantitatively evaluating the water resistance of high-viscosity modified asphalt before and after aging. Existing photoelectric colorimetry methods typically only use the peak height of the maximum absorbance of the dye mother liquor as an indicator to evaluate the change in solution concentration, reflecting the adhesion performance between asphalt and aggregate. In the spectral results obtained by photoelectric colorimetry, in tests of different aggregates with small exfoliation areas or insufficient exfoliation where the exfoliation area has not changed, it cannot accurately reflect the interfacial adhesion between asphalt and aggregate, and often ignores other changes in the overall characteristic peak. Aging increases and aggregates asphaltenes, and reduces the content of light components, leading to a decrease in adhesion performance. Using the peak height as the sole indicator for evaluating the interfacial adhesion between asphalt and aggregate in photoelectric colorimetry cannot reflect the impact of changes in asphalt aging components on the adhesion performance between asphalt and aggregate. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a quantitative evaluation method for the adhesion performance of asphalt and aggregate, which addresses the technical defects of the current boiling and immersion methods. This invention evaluates the adhesion performance of asphalt through a new evaluation index system, providing a more scientific basis for analyzing the influence of asphalt aging degree on the adhesion performance between asphalt and aggregate, and scientifically predicting the influence of asphalt aging degree on adhesion performance.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A quantitative evaluation method for asphalt-aggregate adhesion properties includes the following steps:

[0009] S1. Place the aggregate coated with asphalt in a dyeing agent solution and heat it by boiling or immersion in water. After filtering the aggregate, the dyeing agent solution after reaction is obtained.

[0010] S2. The dye solution after the reaction in S1 is tested by photoelectric colorimetry to obtain the absorption spectrum. The peak height of the absorption spectrum is h and the full width at half maximum is a.

[0011] The peak height index δ is the ratio of peak height h to half-peak width a, and the peak area index γ is the ratio of peak area s to half-peak width a. The adhesion performance between aged asphalt and aggregate is evaluated based on the peak height index δ or the peak area index γ.

[0012] This invention uses the three elements of absorption spectroscopy, namely peak height, half-peak width, and peak area, as a new evaluation index system to provide a more scientific basis for analyzing the influence of asphalt aging degree on the adhesion performance between asphalt and aggregates, and to scientifically predict the influence of asphalt aging degree on adhesion performance.

[0013] In a preferred embodiment of the present invention, when δ≤0.0160 au / nm or γ≤1.1900 au, asphalt is not suitable as a binder for preparing asphalt-basalt aggregate mixtures.

[0014] When δ ≤ 0.0160 au / nm or γ ≤ 1.1900 au, the asphalt exhibits poor complete adhesion, making it unsuitable as a binder for preparing asphalt-aggregate mixtures. When δ > 0.0160 au / nm and γ > 1.1900 au, asphalt is suitable as a binder for preparing asphalt-aggregate mixtures.

[0015] This invention directly evaluates the adhesion performance between aged asphalt and aggregate based on the range of peak height index δ or peak area index γ, and quantitatively evaluates the variation law of asphalt adhesion performance.

[0016] For asphalt-basalt matrix, when δ≤0.0160 au / nm or γ≤1.2200 au, the asphalt has poor adhesion and is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0017] For A-fiber modified asphalt-basalt, when δ≤0.0163 au / nm or γ≤1.2400 au, the asphalt has poor complete adhesion, and asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0018] For B-fiber modified asphalt-basalt, when δ≤0.0163 au / nm or γ≤1.2600 au, the asphalt has poor complete adhesion, and asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0019] For SBS modified bitumen-basalt, when δ≤0.0164au / nm or γ≤1.2700 au, the bitumen has poor adhesion and is not suitable as a binder for preparing bitumen-aggregate mixtures.

[0020] For A-fiber / SBS modified asphalt-basalt, when δ≤0.0163 au / nm or γ≤1.2600 au, the asphalt has poor complete adhesion, and the asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0021] For B-fiber / SBS modified asphalt-basalt, when δ≤0.0163 au / nm or γ≤1.2500 au, the asphalt has poor complete adhesion, and the asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0022] In a preferred embodiment of the present invention, when δ≤0.013 au / nm or γ≤1.0 au, asphalt is not suitable as a binder for preparing asphalt-granite aggregate mixtures.

[0023] When δ ≤ 0.013 au / nm or γ ≤ 1.0 au, the asphalt exhibits poor complete adhesion, making it unsuitable as a binder for preparing asphalt-granite aggregate mixtures. When δ > 0.013 au / nm and γ > 1.0 au, asphalt is suitable as a binder for preparing asphalt-granite aggregate mixtures.

[0024] For base bitumen-granite, when δ≤0.0160 au / nm or γ≤1.2100 au, the bitumen has poor complete adhesion and is not suitable as a binder for preparing bitumen-aggregate mixtures.

[0025] For A-fiber modified asphalt-granite, when δ≤0.0160 au / nm or γ≤1.2100 au, the asphalt has poor complete adhesion, and asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0026] For B-fiber modified asphalt-granite, when δ≤0.0160 au / nm or γ≤1.1900 au, the asphalt has poor complete adhesion, and asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0027] For SBS-modified asphalt-granite, when δ≤0.0160 au / nm or γ≤1.2000 au, the asphalt has poor complete adhesion, and asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0028] For A-fiber / SBS modified asphalt-granite, when δ≤0.0160 au / nm or γ≤1.1900 au, the asphalt has poor complete adhesion, and asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0029] For B-fiber / SBS modified asphalt-granite, when δ≤0.0160 au / nm or γ≤1.2300 au, the asphalt has poor complete adhesion, and the asphalt is not suitable as a binder for preparing asphalt-aggregate mixtures.

[0030] In a preferred embodiment of the present invention, asphalt-basalt pavement requires maintenance when δ≤0.0164 au / nm or γ≤1.2723 au;

[0031] Asphalt-granite pavements require maintenance when δ≤0.0163 au / nm or γ≤1.2746 au.

[0032] When the road surface is within the above-mentioned range, the degree of road surface aging exceeds the simulated aging of 40 hours in a rotating thin film oven (RTFO) or pressure aging vessel (PAV), and road surface maintenance is required.

[0033] In a preferred embodiment of the present invention, the photoelectric colorimetric test uses a scanning wavelength of 300 nm to 700 nm, a high scanning speed, absorbance measurement, a direct detection unit, and a light source conversion wavelength of 310 nm. The characteristic peak of Pf can be clearly observed at wavelengths of 300 nm to 700 nm.

[0034] In a preferred embodiment of the present invention, when |γ-δ|≥1.0, it indicates that the γ and δ measurements are accurate.

[0035] The peak height index δ or peak area index γ can be used to corroborate each other to verify the accuracy of the evaluation of asphalt adhesion performance, thereby improving the accuracy of the evaluation of asphalt adhesion performance.

[0036] In a preferred embodiment of the present invention, the same test solution is tested at least twice in parallel, and the difference between the results of the two parallel tests is no greater than 0.02%.

[0037] In a preferred embodiment of the present invention, the staining agent solution is a phenol-saffron solution, gentian violet, or thymol blue. Phenolic saffron solution, gentian violet, or thymol blue can be used for photoelectric colorimetric testing, and can be adsorbed by the aggregate, thus staining the aggregate. Preferably, the staining agent solution is a phenol-saffron solution.

[0038] In a preferred embodiment of the present invention, the concentration of the staining agent solution is 0.002 mg / mL to 0.10 mg / mL.

[0039] In a preferred embodiment of the present invention, the boiling method involves heating the food in boiling water for 1 to 20 minutes.

[0040] In a preferred embodiment of the present invention, the heating temperature of the water immersion method is 50-70°C, and the heating time of the water immersion method is 1-3 hours.

[0041] In a preferred embodiment of the present invention, the asphalt includes one or more of base asphalt, fiber-modified asphalt, SBS-modified asphalt, and fiber / SBS-modified asphalt.

[0042] The present invention also includes the following steps:

[0043] S3. Short-term and long-term thermo-oxidative aging of asphalt were carried out to obtain asphalt with different aging degrees.

[0044] S4. Based on the aforementioned quantitative evaluation method, test the peak height index δ and peak area index γ of asphalt with different aging degrees in S3. Linearly fit the peak height index δ and peak area index γ with aging time to establish the correlation between adhesion performance and aging performance.

[0045] In S3, a rotating thin-film oven (RTFO) and a pressure aging vessel (PAV) were used to simulate the short-term and long-term thermo-oxidative aging of asphalt, respectively.

[0046] Based on the correlation line between adhesion performance and aging performance, the degree of asphalt aging and adhesion performance can be predicted according to the asphalt peak height index δ and peak area index γ. Alternatively, the asphalt peak height index δ and peak area index γ can be predicted according to the degree of asphalt aging and adhesion performance, thus achieving bidirectional prediction of asphalt aging and adhesion performance.

[0047] This invention first conducts rotating thin film oven aging (RTFO) and pressure aging vessel (PAV) experiments on base asphalt and different modified asphalts respectively to simulate short-term and long-term aging of asphalt during construction and use. Second, aggregates are coated with modified asphalts of different aging degrees and subjected to water immersion tests. The solutions after water immersion are tested by photoelectric colorimetry, and the absorption spectrum data are analyzed to calculate the peak height index (δ) and peak area index (γ). δ is the ratio of peak height to half-peak width, and γ is the ratio of peak area to half-peak width. Based on δ and γ, the spalling rate of asphalt and aggregates before and after aging is quantitatively calculated.

[0048] The more asphalt is stripped from the aggregate surface, the more phenolic resin is absorbed, resulting in a smaller absorbance peak, a larger half-peak width, and a smaller δ value in the photoelectric colorimetric spectrum, reflecting poorer adhesion between asphalt and aggregate. Similarly, as the degree of asphalt stripping on the aggregate surface increases, the peak area decreases, the half-peak width increases, and the γ value decreases, indicating that a smaller γ value indicates poorer adhesion between asphalt and aggregate.

[0049] The specific steps of this invention include the following:

[0050] The absorbance change of Pf solution was tested by photoelectric colorimetry. Based on the spectral data of the absorption peak, a new evaluation index system was defined to analyze the adhesion performance between aged asphalt and aggregate, providing a scientific testing method for evaluating the adhesion performance between aged asphalt and aggregate.

[0051] (1) Prepare asphalt samples and treat them with different degrees of aging.

[0052] (2) After cleaning the aggregate, heat it to remove the moisture. Mix the asphalt before and after aging with the dried aggregate in a certain proportion so that the surface of the aggregate is fully coated with asphalt.

[0053] (3) Prepare a Pf solution of a certain concentration, place the aggregate wrapped with asphalt in the Pf solution for boiling or soaking in water and heating, and obtain the Pf after the experiment.

[0054] (4) The Pf after immersion in water was tested by photoelectric colorimetry, and the absorption spectrum data was obtained and the adhesion performance index δ and γ were calculated.

[0055] The peak height, half-peak width, and peak area of ​​the absorption peaks resulting from changes in dye concentration are combined as parameters for assessing asphalt aging, thereby quantitatively evaluating the degree of asphalt aging.

[0056] To more comprehensively analyze and grasp the important laws reflected by the spectrum, water immersion experiments were conducted on modified asphalt with different aging degrees and different aggregates to fully characterize the main characteristics of the adhesion process before and after asphalt aging. It is evident that using photoelectric colorimetry and a new evaluation index system to evaluate the aging behavior and adhesion performance prediction of asphalt mixtures is beneficial for quality evaluation of asphalt mixtures, guiding the matching and selection of asphalt and mixtures, providing scientific evaluation indicators and predicting the optimal maintenance time for preventive maintenance of asphalt pavements, and establishing a scientific and effective evaluation method for assessing and analyzing the aging degree of asphalt before the recycling of waste asphalt mixtures. This application is of great significance for formulating asphalt pavement maintenance decisions and maintenance plans.

[0057] Compared with existing evaluation methods, the beneficial technical effects of this invention are as follows:

[0058] (1) Based on photoelectric colorimetry, this invention analyzes the variation law of peak height, half peak width and peak area of ​​absorption spectrum, which has high accuracy and can quantitatively evaluate the variation law of asphalt adhesion performance. It can overcome the influence of large human factors in the evaluation of high viscosity modified asphalt by boiling water method and water immersion method. It has great advantages in the quantitative evaluation of the water damage resistance of high viscosity modified asphalt after aging.

[0059] (2) The adhesion performance indices δ and γ defined in this invention are new indices for evaluating the adhesion performance between asphalt and aggregates. They can more comprehensively grasp the important laws reflected in the absorption spectrum results of the changes in asphalt aging components. They provide a more scientific and effective evaluation method for the comprehensive analysis and prediction of the aging behavior and adhesion performance of asphalt. They are of great significance for the durability evaluation of asphalt mixtures, guiding the matching selection of asphalt and mixtures, predicting the maintenance time of asphalt pavement, and assessing the degree of asphalt aging of asphalt mixtures in the reconstruction of old roads. Attached Figure Description

[0060] Figure 1 The absorption spectra of phenol-saffron solutions at different concentrations are shown.

[0061] Figure 2 These are actual images of composite modified asphalt and aggregates with different aging levels after water immersion.

[0062] Figure 3 The relationship between asphalt and aggregates with different aging degrees and peak height index δ is shown in the graphs: (a) basalt, (b) granite.

[0063] Figure 4 The graph shows the relationship between asphalt and aggregate with different aging degrees and peak area index γ: (a) basalt, (b) granite.

[0064] Figure 5 This is a schematic diagram illustrating the operation in the embodiment. Detailed Implementation

[0065] In order to evaluate the variation law of adhesion performance between asphalt and aggregate, the embodiments described in this invention are only some embodiments of this invention, and are not limited to a single modified asphalt. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0066] This invention provides a method for predicting asphalt aging and evaluating asphalt-aggregate adhesion properties, comprising the following steps:

[0067] (1) Preparation and aging treatment of modified asphalt

[0068] 1) Modified asphalt was prepared using a high-speed disperser and a high-speed shear tester, with the corresponding shear rate and experimental temperature controlled.

[0069] 2) According to the T 0610-2011 specification of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), short-term aged samples were obtained by rotating and aging in a rotary film oven (RTFO) at 163℃ for 75 minutes.

[0070] 3) According to the provisions of T 0630-2011 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), short-term aged asphalt samples are taken and aged in a pressure aging vessel (PAV) at 100℃ and 2.1MPa±0.1MPa atmospheric pressure for a certain period of time to obtain long-term aged samples.

[0071] (2) Photoelectric colorimetric method test

[0072] 1) Prepare phenol-saffron (Pf) solutions at concentrations of 0.002 mg / mL, 0.004 mg / mL, 0.006 mg / mL, 0.008 mg / mL, and 0.010 mg / mL, and perform photoelectric colorimetric analysis to determine the relationship between Pf solution concentration and absorption peak. The test results are as follows: Figure 1As shown in the figure, it can be seen that as the concentration decreases, the peak height of the absorption peak decreases, the peak area decreases, and the half-width at half-maximum (HWHM) increases. The ratio of peak height to HWHM, δ, decreases with decreasing Pf solution concentration; the ratio of peak area to HWHM, γ, also decreases with decreasing Pf solution concentration. The greater the degree of asphalt spalling on the aggregate surface, the more significant the decrease in Pf solution concentration, indicating that the smaller δ is, the worse the adhesion between asphalt and aggregate; the smaller γ is, the worse the asphalt's resistance to water damage.

[0073] 2) Clean and remove dust from the surface of the aggregate, heat it in an oven to dry it thoroughly, weigh the asphalt before aging, after RTFO aging and after PAV aging, and mix them separately in the oven so that the surface of the aggregate is fully coated with asphalt.

[0074] 3) Take the aggregate samples from 2) containing asphalt with different aging degrees and place them in a beaker containing 0.010 mg / mL Pf solution. After incubating in a water bath at 60℃ for 2 hours, take the solutions and perform photoelectric colorimetric tests. The scanning wavelength for the photoelectric colorimetric test is 300nm~700nm, the scanning speed is "high speed", the measurement mode is "absorbance value", the detection unit is "direct", and the light source conversion wavelength is 310nm. Analyze the peak height, half-peak width, and peak area of ​​the absorption spectrum.

[0075] (3) Calculate the adhesion performance index and predict the degree of asphalt aging.

[0076] To more comprehensively analyze and grasp the important laws reflected in the absorption spectrum, the ratio of half-width to peak height is defined as the peak height index (δ), and the ratio of peak area to peak height is defined as the peak area index (γ) for evaluation and analysis. Based on δ and γ, the spalling rate of asphalt and aggregate before and after aging is quantitatively calculated. The correlation between the adhesion performance indices δ and γ and aging time is established to predict the degree of asphalt aging.

[0077] The traditional methods of boiling and immersion in water to determine the adhesion between asphalt and aggregate before and after aging are highly subjective, especially in high-viscosity modified asphalt where it is difficult to distinguish the degree of asphalt spalling. Figure 2 The images show the surface morphology of composite modified asphalt and aggregate after water immersion at different aging levels. Before aging, the asphalt and aggregate exhibit good adhesion, with an adhesion grade of 4 determined according to T0616-1993 of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2011). After short-term aging and long-term aging, the adhesion grades between the asphalt and aggregate are 3 and 2, respectively.

[0078] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0079] Example 1

[0080] The base asphalt control group was prepared as follows: the base asphalt was heated to a molten state in an oven at 160℃, dispersed using a high-speed disperser at 500 rpm for 1 hour, and the temperature was controlled at 170℃ using a constant temperature mantle. Then, it was sheared and dispersed using a high-speed shear apparatus at 5000 rpm and 170℃ for 1 hour to obtain the base asphalt BA control group.

[0081] Cleaned basalt and granite were heated at 150℃ until their mass remained unchanged. The two aggregates were then separately mixed with asphalt before aging, after RTFO aging, and after PAV aging in an oven (160℃~180℃) to ensure the aggregate surface was fully coated with asphalt. After cooling at room temperature, a water immersion test was conducted, followed by a 2-hour water bath at 60℃. The resulting solutions were analyzed using photoelectric colorimetry, and the spectral data were examined.

[0082] Example 2

[0083] The preparation steps for fiber-modified asphalt are as shown in Example 1, except that:

[0084] A fiber modified asphalt is prepared by adding a certain mass percentage of A fiber to the base asphalt and dispersing and shearing it.

[0085] Cleaned basalt and granite were heated at high temperatures until their mass remained unchanged. The two aggregates were then separately mixed with asphalt before aging, after RTFO aging, and after PAV aging in an oven, ensuring the aggregate surface was fully coated with asphalt. After cooling at room temperature, water immersion tests were conducted. The resulting solutions were then analyzed using photoelectric colorimetry to obtain the spectral data.

[0086] Example 3

[0087] The preparation steps for B-fiber modified asphalt are as shown in Example 1, with the difference being:

[0088] A certain percentage by mass of B fibers is added to the base asphalt for dispersion and shearing to prepare B fiber modified asphalt.

[0089] Cleaned basalt and granite were heated at high temperatures until their mass remained unchanged. The two aggregates were then separately mixed with asphalt before aging, after RTFO aging, and after PAV aging in an oven, ensuring the aggregate surface was fully coated with asphalt. After cooling at room temperature, water immersion tests were conducted. The resulting solutions were then analyzed using photoelectric colorimetry to obtain the spectral data.

[0090] Example 4

[0091] The method for preparing SBS modified asphalt is as follows: the base asphalt is heated to a molten state in an oven at 160℃, a certain mass of SBS modifier is added, and the mixture is dispersed using a high-speed disperser and fully sheared and dispersed using a high-speed shear apparatus at a certain speed and experimental temperature to obtain SBS modified asphalt.

[0092] Cleaned basalt and granite were heated at high temperatures until their mass remained unchanged. The two aggregates were then separately mixed with SBS modified asphalt before aging, after RTFO aging, and after PAV aging in an oven, ensuring the aggregate surface was fully coated with asphalt. After cooling at room temperature, water immersion tests were conducted. The resulting solutions were then analyzed using photoelectric colorimetry to obtain spectral data.

[0093] Example 5

[0094] The self-made A-fiber / SBS modified asphalt was prepared by the following method: SBS modified asphalt was prepared according to Example 4, and a certain mass of A-fiber was added to the SBS modified asphalt. The asphalt was dispersed using a high-speed disperser and fully sheared and dispersed using a high-speed shear apparatus at a certain speed and experimental temperature to obtain A-fiber / SBS modified asphalt.

[0095] Cleaned basalt and granite were heated at high temperatures until their mass remained unchanged. The two aggregates were then separately mixed with A-fiber / SBS modified asphalt before aging, after RTFO aging, and after PAV aging in an oven to ensure the aggregate surface was fully coated with asphalt. After cooling at room temperature, water immersion tests were conducted. The resulting solutions were analyzed using photoelectric colorimetry to obtain spectral data.

[0096] Example 6

[0097] The preparation steps for B-fiber / SBS modified bitumen are as shown in Example 5, except that:

[0098] A certain mass ratio of B fibers was added to SBS modified asphalt for dispersion and shearing to prepare B fiber / SBS modified asphalt.

[0099] Cleaned basalt and granite were heated at high temperatures until their mass remained unchanged. The two aggregates were then separately mixed with asphalt before aging, after RTFO aging, and after PAV aging in an oven, ensuring the aggregate surface was fully coated with asphalt. After cooling at room temperature, water immersion tests were conducted. The resulting solutions were then analyzed using photoelectric colorimetry to obtain the spectral data.

[0100] Comparative Example 1

[0101] Cleaned basalt and granite were heated at high temperatures until their mass remained unchanged and the aggregate surface was not coated with asphalt. After cooling at room temperature, a water immersion test was conducted. The resulting solution was then analyzed using photoelectric colorimetry to obtain the spectral data.

[0102] The shear dispersion parameters, water immersion test conditions, and photoelectric colorimetric test parameters in Comparative Example 1 and Examples 2-6 are the same as those in Example 1.

[0103] Based on the test results of various embodiments, as shown in Tables 1 and 2, the peak height index and peak area index of asphalt and aggregate show a decreasing trend with increasing aging. The blank experiment (Comparative Example 1) indicates that the asphalt completely peels off from the aggregate surface, indicating severe asphalt aging and complete loss of adhesion between the asphalt and aggregate. Determining the reference ranges for δ and γ can be used to determine the timing of asphalt pavement maintenance and guide the matching selection of asphalt and mixture. Therefore, when δ ≤ 0.0160 au / nm or γ ≤ 1.1900 au, asphalt is not suitable as a binder for preparing asphalt-basalt aggregate mixtures. When δ ≤ 0.013 au / nm or γ ≤ 1.0 au, asphalt is not suitable as a binder for preparing asphalt-granite aggregate mixtures. The reference values ​​for peak height index and peak area index differ for different aggregates, and the protection of this invention is not limited to the above reference range values.

[0104] Figure 3 This represents a linear fit between the degree of asphalt aging and the peak height index. Figure 4 The fitting relationship between asphalt aging degree and peak area index is shown. With increasing asphalt aging time, both peak height index and peak area index show a decreasing trend, indicating that aged asphalt has reduced adhesion to aggregates. The correlation coefficient between asphalt aging degree and peak height index ranges from 0.748 to 0.977, indicating that the peak height index can predict the impact of asphalt aging on adhesion performance to some extent. During the aging process, the content of asphaltene and lightweight components changes, and the asphalt aging degree shows a good correlation with the peak height index, indicating a statistical correlation between the asphalt absorption area and asphalt aging behavior. Both peak height index and peak area index can effectively predict asphalt aging behavior and adhesion performance in both directions.

[0105] Table 1. Absorption spectral analysis results of asphalt and basalt aggregates

[0106]

[0107] Table 2. Absorption spectral analysis results of asphalt and granite aggregates

[0108]

[0109] Comparative Example 2

[0110] Composite modified asphalt was prepared by using warm mix agent 1 and SBS. The preparation method was as follows: a certain mass ratio of warm mix agent 1 was added to molten base asphalt, and after thorough stirring, a certain mass ratio of SBS was added. The mixture was dispersed using a high-speed disperser and then fully sheared and dispersed using a high-speed shear apparatus at a certain speed and experimental temperature to obtain warm mix agent 1 / SBS modified asphalt.

[0111] Cleaned basalt and granite were heated at high temperatures until their mass remained unchanged. The two aggregates were then separately mixed with warm mix 1 / SBS modified asphalt before aging, after RTFO aging, and after PAV aging in an oven to ensure the aggregate surface was fully coated with asphalt. After cooling at room temperature, water immersion (or boiling) tests were conducted. The resulting solutions were analyzed using photoelectric colorimetry, and the spectral data are shown in Table 3.

[0112] Comparative Example 3

[0113] Composite modified asphalt was prepared using warm mix additive 2 and SBS. The steps for preparing warm mix additive 2 / SBS modified asphalt are shown in Comparative Example 2, with the following differences:

[0114] A certain mass ratio of warm mix agent 2 was added to SBS modified asphalt for dispersion and shearing to prepare warm mix agent 2 / SBS modified asphalt. The test spectral data results are shown in Table 3.

[0115] Using only peak height and peak area to evaluate the adhesion properties of asphalt fails to adequately reflect the degree of asphalt aging, as shown in Table 3. Photoelectric colorimetry can establish a good correlation between the adhesion properties of asphalt and aggregates and the degree of aging. The aging and adhesion properties of asphalt can be determined based on the values ​​of δ and γ, which are related to the initial concentration of the Pf solution. Therefore, the scope of protection of this invention is not limited to the Pf concentration, asphalt type, and aggregate type in the above embodiments.

[0116] Table 3. Analysis results of absorption spectral data of different warm-mix modified asphalts

[0117]

[0118] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, any improvements and modifications obtained without departing from the technical concept of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A quantitative evaluation method for asphalt-aggregate adhesion performance, characterized in that, Includes the following steps: S1. Place the aggregate coated with asphalt in a dyeing agent solution and heat it by boiling or immersion in water. After filtering the aggregate, the dyeing agent solution after reaction is obtained. S2. The dye solution after the reaction in S1 is tested by photoelectric colorimetry to obtain the absorption spectrum. The peak height of the absorption spectrum is h and the full width at half maximum is a. The peak height index δ is the ratio of peak height h to half-peak width a, and the peak area index γ is the ratio of peak area s to half-peak width a. The adhesion performance between aged asphalt and aggregate is evaluated based on the peak height index δ or the peak area index γ. When δ≤0.0164 au / nm or γ≤1.2723 au, asphalt-basalt aggregate pavement requires maintenance; When δ≤0.0163 au / nm or γ≤1.2746 au, asphalt-granite aggregate pavement requires maintenance; When |γ-δ|≥1.0, it indicates that the measurements of γ and δ are accurate.

2. The quantitative evaluation method for asphalt-aggregate adhesion performance according to claim 1, characterized in that: When δ≤0.0160 au / nm or γ≤1.1900 au, bitumen is not suitable as a binder for preparing bitumen-basalt aggregate mixtures.

3. The quantitative evaluation method for asphalt-aggregate adhesion performance according to claim 1, characterized in that: When δ≤0.013 au / nm or γ≤1.0 au, asphalt is not suitable as a binder for preparing asphalt-granite aggregate mixtures.

4. The quantitative evaluation method for asphalt-aggregate adhesion performance according to claim 1, characterized in that: The photoelectric colorimetric method uses a scanning wavelength of 300nm to 700nm, a high scanning speed, an absorbance measurement method, a direct detection unit, and a light source conversion wavelength of 310nm.

5. The quantitative evaluation method for asphalt-aggregate adhesion performance according to any one of claims 1-4, characterized in that: The same test solution should be tested in at least two parallel tests, and the difference between the results of the two parallel tests should not exceed 0.02%.

6. The quantitative evaluation method for asphalt-aggregate adhesion performance according to any one of claims 1-4, characterized in that: The heating temperature for the water immersion method is 50–70℃, and the heating time is 1–3 hours.

7. The quantitative evaluation method for asphalt-aggregate adhesion performance according to any one of claims 1-4, characterized in that: The asphalt includes one or more of the following: base asphalt, fiber-modified asphalt, SBS-modified asphalt, and fiber / SBS-modified asphalt.

8. The quantitative evaluation method for asphalt-aggregate adhesion performance according to any one of claims 1-4, characterized in that... It also includes the following steps: S3. Short-term and long-term thermo-oxidative aging of asphalt were carried out to obtain asphalt with different aging degrees. S4. According to the method in claim 1, test the peak height index δ and peak area index γ of asphalt with different aging degrees in S3, and linearly fit the peak height index δ and peak area index γ with aging time to establish the correlation between adhesion performance and aging performance.

Images