Method for evaluating pavement performance of asphalt mixture in alkaline water environment

Abstract

The invention discloses a pavement performance evaluation method of an asphalt mixture in an alkaline water environment. The pavement performance evaluation method comprises the following steps: obtaining pavement performance parameters of the asphalt mixture in the alkaline water environment; establishing a fitting curve of the pavement performance parameters and pH of the asphalt mixture in the alkaline water environment; based on the fitted curve and the pavement performance index threshold value of the asphalt mixture in the common environment, obtaining the pavement performance index threshold value of the asphalt mixture in the alkaline water environment; and evaluating the pavement performance of the asphalt mixture based on the pavement performance index threshold value of the asphalt mixture in the alkaline water environment. According to the method, the index threshold value of the asphalt mixture in the alkaline water environment is determined under the condition that the influence of the environmental alkalinity degree on the pavement performance of the asphalt mixture is considered, compared with a fixed index threshold value, the macroscopic test index threshold value dynamically changing along with the change of the pH value is higher in applicability, the evaluation result is more accurate and reasonable, and the method is suitable for popularization and application. The requirements of the actual service environment of the asphalt pavement are met.

Description

Technical Field

[0001] The invention relates to the technical field of asphalt mixture engineering, and in particular to a method for evaluating the road performance of asphalt mixture in an alkaline water environment. Background Art

[0002] Pavement whitening is one of the common early diseases of asphalt pavement. Because the water in the whitening area is highly alkaline, it is also called efflorescence disease. This disease usually occurs in the asphalt pavement layer on the cement mixture bridge deck or cement stabilized base. At the same time, efflorescence often occurs in the early stage of project completion, that is, it will occur without the action of traffic load. With the opening of the project, the efflorescence disease will further develop into a more serious disease.

[0003] Through on-site observation of the disease, it was found that the areas where efflorescence occurred had a common feature, that is, the efflorescence substances were mainly concentrated near the obvious gaps in the asphalt mixture. Subsequent studies found that the substances that cause efflorescence on asphalt pavements are transmitted to the road surface in the form of a solution along with water, and after the water evaporates, the crystal particles precipitate and adhere to the surface of the asphalt pavement. Core sampling was carried out in the efflorescence area and the normal area respectively. By observing the inside of the core holes, it was found that after the mechanical water used in the core drilling was drained and left to stand for a period of time, water would spontaneously gather inside the core holes and form water accumulation. The water accumulation in the core holes was tested using pH test paper, and it was found that the water accumulated in the core sample holes in the efflorescence area was alkaline (pH value was around 10~12), while the water accumulated in the core sample holes in the non-disease area was neutral. The ionic composition of the alkaline solution in the core hole was tested, and the alkaline solution contained Ca 2+ , K + 、Al 3+ Based on the characteristic components of cement materials such as alkali-bearing, combined with the fact that alkali-bearing diseases of asphalt pavements frequently occur in cement bridge decks or dense-graded asphalt mixture pavement layers on cement-stabilized bases, it is believed that alkaline substances in cement materials are one of the main causes of alkali-bearing diseases in cement bridge decks or dense-graded asphalt mixture pavement layers on cement-stabilized bases in an alkaline water environment. At the same time, the whitening substances move from bottom to top in the asphalt surface layer in the form of alkaline solutions before precipitation, causing the surface asphalt mixture to be in an alkaline water environment, which has an adverse effect on the performance of asphalt pavements. In an alkaline water environment, the adhesion of asphalt decreases, the cohesion decreases, the asphalt-aggregate interface is more prone to adhesion failure, the asphalt mixture has a worse ability to resist alkaline water erosion, and the water damage phenomenon is more serious. The alkaline water environment will also cause the macroscopic performance of the asphalt mixture to decay. Compared with the neutral and acidic liquid environments, the performance of the asphalt mixture in the alkaline environment, such as the splitting strength, maximum bending tensile strain, and freeze-thaw splitting strength, is most seriously degraded.

[0004] The Technical Specifications for Highway Asphalt Pavement Construction stipulates the road performance index requirements for asphalt mixtures under normal conditions. However, in actual use, the environment in which the asphalt mixture is located will inevitably not maintain the environment set for conventional tests, which leads to the problem that some indoor test indicators are compliant, but still cannot meet the requirements in actual use. Therefore, in order to prevent and reduce the new form of water damage in asphalt pavement whitening disease and make up for the lack of existing research on the effect of alkaline solutions on the asphalt-aggregate interface, it is urgent to provide a road performance evaluation method for asphalt mixtures in an alkaline water environment. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, propose a method for evaluating the road performance of asphalt mixtures in an alkaline water environment, and solve the technical problem that the road performance index requirements of asphalt mixtures in ordinary environments in the prior art cannot meet the use requirements in alkaline water environments.

[0006] The present invention provides a method for evaluating the road performance of asphalt mixture in an alkaline water environment, comprising the following steps: Obtain the road performance parameters of asphalt mixture in alkaline water environment; Establish the fitting curve between the road performance parameters and pH of asphalt mixture in alkaline water environment; Based on the fitting curve and the road performance index threshold of asphalt mixture under normal environment, the road performance index threshold of asphalt mixture under alkaline water environment is obtained; The road performance of asphalt mixture is evaluated based on the road performance index threshold of asphalt mixture in alkaline water environment.

[0007] Compared with the prior art, the beneficial effects of the present invention include: The present invention determines the index threshold of asphalt mixture in alkaline water environment while taking into account the influence of environmental alkalinity on the road performance of asphalt mixture. Compared with fixed index threshold, the macro test index threshold that changes dynamically with the pH value is more applicable, and its evaluation result is more accurate and reasonable, and more in line with the requirements of the actual service environment of asphalt pavement. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a process flow chart of an implementation method of a road performance evaluation method of asphalt mixture in an alkaline water environment provided by the present invention; Figure 2 These are several groups of 70# matrix asphalt mixture Marshall specimens prepared under the same conditions as in Example 1 of the present invention; Figure 3 are several groups of SBS modified asphalt mixture Marshall specimens prepared under the same conditions as in Example 1 of the present invention; Figure 4This is a graph showing the test results of the water-residual stability of the 70# matrix asphalt mixture in Example 1 of the present invention; Figure 5 is a graph showing the test result of the water-immersion residual stability of the SBS modified asphalt mixture in Example 1 of the present invention; Figure 6 This is a freeze-thaw splitting test result diagram of the 70# base asphalt mixture in Example 1 of the present invention; Figure 7 is a freeze-thaw splitting test result diagram of the SBS modified asphalt mixture in Example 1 of the present invention; Figure 8 It is a fitting diagram of the test results of the residual stability of the 70# matrix asphalt mixture in Example 1 of the present invention; Fig. 9 is a fitting diagram of the water-residual stability test results of the SBS modified asphalt mixture in Example 1 of the present invention; Fig.10 It is a fitting diagram of the freeze-thaw cycle test results of the 70# matrix asphalt mixture in Example 1 of the present invention; Fig.11 It is a fitting diagram of the freeze-thaw cycle test results of the SBS modified asphalt mixture in Example 1 of the present invention. DETAILED DESCRIPTION

[0009] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0010] See also Figure 1 The present invention provides a method for evaluating the road performance of asphalt mixture in an alkaline water environment, comprising the following steps: S1. Obtaining road performance parameters of asphalt mixture in alkaline water environment; S2. Establish a fitting curve between the road performance parameters and pH of asphalt mixture in an alkaline water environment; S3. Based on the fitting curve and the road performance index threshold of the asphalt mixture under normal environment, the road performance index threshold of the asphalt mixture under alkaline water environment is obtained; S4. Evaluate the road performance of asphalt mixture based on the road performance index threshold of asphalt mixture in alkaline water environment.

[0011] In practical applications, asphalt mixtures are at risk of being in an alkaline environment, so the impact of the alkaline environment on the performance of asphalt mixtures needs to be considered during indoor tests. The present invention determines the index threshold of asphalt mixtures in an alkaline water environment based on the road performance index threshold of asphalt mixtures in a normal environment and the fitting curve of the road performance parameters of asphalt mixtures in an alkaline water environment and pH, while considering the impact of the alkalinity of the environment on the road performance of asphalt mixtures. The materials used in the project are screened based on whether the test results of asphalt mixtures in different alkaline environments meet the threshold requirements; at the same time, compared with the fixed index threshold, the macro test index threshold that changes dynamically with the pH value is more applicable, and its evaluation result is more accurate and reasonable, and more in line with the requirements of the actual service environment of asphalt pavement. In addition, the fitting curve of the road performance parameters of asphalt mixtures in an alkaline water environment and pH can reflect the changing trend of asphalt mixture performance with pH value. The index change with a similar trend obtained according to the changing trend of the fitting curve according to the index threshold of asphalt mixtures in a normal environment has a good reference significance.

[0012] In this embodiment, the pH of the alkaline water environment is greater than 7. In some specific embodiments of the present invention, the pH of the alkaline water environment is 8 to 14, including but not limited to 8, 10, 12, 14, etc.

[0013] In this embodiment, the number of alkaline water environments is ≥ 3. Those skilled in the art know that the more types of alkaline water environments there are, the more favorable it is for improving the accuracy of the fitting results, but too many types of alkaline water environments will increase the workload. In some specific embodiments of the present invention, the number of alkaline water environments is 3 to 5, for example, 3, 4, and 5.

[0014] In this embodiment, the asphalt mixture includes ordinary asphalt mixture and / or modified asphalt mixture.

[0015] The present invention does not limit the grading mode of the asphalt mixture, and those skilled in the art can select it according to actual conditions. In some specific embodiments of the present invention, the ordinary asphalt mixture is a 70# base asphalt mixture with a grading of AC-20C, and the modified asphalt mixture is an SBS modified asphalt mixture with a grading of AC-20C.

[0016] The present invention does not limit the road performance, and those skilled in the art can select according to actual conditions. In some specific embodiments of the present invention, the road performance includes at least one of water immersion residual stability, splitting strength ratio, maximum bending tensile strain ratio, and freeze-thaw splitting strength ratio.

[0017] In this implementation, step S1 includes: S11, providing an asphalt mixture and an alkaline solution with different pH values; S12. The asphalt mixture is corroded by alkaline solutions with different pH values, and the road performance of the asphalt mixture after the corrosion treatment is tested to obtain road performance parameters of the asphalt mixture in an alkaline water environment.

[0018] The present invention utilizes alkaline solution to simulate actual working conditions to corrode different test pieces, and then conducts road performance tests (macroscopic water stability performance tests) on the asphalt mixture before and after corrosion, analyzes the change law of the road performance of the asphalt mixture in the alkaline water environment, and provides a reference basis for the material optimization of the asphalt mixture in the alkaline water environment.

[0019] The present invention does not limit the type of alkaline solution, and those skilled in the art can choose according to actual conditions. In some specific embodiments of the present invention, the alkaline solution is at least one of a sodium hydroxide solution, a potassium hydroxide solution or a calcium hydroxide solution, preferably a sodium hydroxide solution and a potassium hydroxide solution. From the formation mechanism of efflorescence of asphalt pavement, it is found that Ca(OH)2 solution is the main solution that produces whitening of asphalt pavement. Given the low solubility of Ca(OH)2 in water, and the fact that Ca(OH)2 solution reacts with CO2 in the air to generate CaCO3, which will affect the OH in the solution. − Ion concentration: NaOH and KOH can be completely ionized in water, making the solution alkaline, and have high solubility in water. The solution can be stored stably and does not react with components in the air. It can provide a good alkaline solution environment for analyzing OH − The influence of ions on the asphalt-aggregate interface adhesion. Therefore, the present invention preferably uses alkaline solution NaOH solution or KOH solution to replace the actual working conditions.

[0020] In some specific embodiments of the present invention, the road performance is the residual stability of water immersion, and step S12 includes: S121A, performing alkali leaching treatment on the asphalt mixture by using alkaline solutions with different pH values, then performing water immersion treatment on the asphalt mixture after the alkali leaching treatment, and then performing a stability test on the asphalt mixture after the water immersion treatment to obtain the stability after the alkali leaching treatment; S122A, subjecting the asphalt mixture to water immersion treatment, and then conducting a stability test on the asphalt mixture after the water immersion treatment to obtain the stability after the asphalt mixture has not been subjected to alkali immersion treatment; S123A. Establish a calculation formula for the water-immersion residual stability, and obtain the water-immersion residual stability based on the stability after alkali immersion treatment and the stability after no alkali immersion treatment.

[0021] The present invention does not limit the order of steps S121A and S122A.

[0022] More specifically, the temperature of the alkali leaching treatment is 20-30°C, including but not limited to 20°C, 22°C, 25°C, 28°C, 30°C, etc.; the time of the alkali leaching treatment is 6-8 days, including but not limited to 6, 7, 8, etc.

[0023] More specifically, the temperature of the water immersion treatment is 55~65℃, including but not limited to 55℃, 58℃, 60℃, 62℃, 65℃, etc.; the time of the water immersion treatment is 30~40min, including but not limited to 30min, 32min, 34min, 36min, 38min, 40min, etc.

[0024] More specifically, the calculation formula for the residual stability after immersion is: (1) Where: MS is the stability before alkali immersion treatment, kN; MS1 is the stability after alkali immersion treatment, kN; MS0 is the residual stability of the specimen after immersion in water, %.

[0025] In some specific embodiments of the present invention, the road performance is a freeze-thaw splitting tensile strength ratio, and step S12 includes: S121B, subjecting the asphalt mixture to freeze-thaw cycle treatment by using alkaline solutions with different pH values, then subjecting the asphalt mixture subjected to freeze-thaw cycle treatment to water immersion treatment, and then subjecting the asphalt mixture subjected to water immersion treatment to a splitting tensile strength test to obtain the splitting tensile strength after the freeze-thaw cycle treatment; S122B, subjecting the asphalt mixture to water immersion treatment, and then conducting a splitting tensile strength test on the asphalt mixture after the water immersion treatment to obtain the splitting tensile strength after not being subjected to freeze-thaw cycle treatment; S123B. Establish a calculation formula for the freeze-thaw splitting tensile strength ratio, and obtain the freeze-thaw splitting tensile strength ratio based on the splitting tensile strength after freeze-thaw cycle treatment and the splitting tensile strength after freeze-thaw cycle treatment.

[0026] The present invention does not limit the order of steps S121B and S122B.

[0027] More specifically, during the freeze-thaw cycle treatment, the temperature of the low-temperature stage is -16~-20℃, including but not limited to -16℃, -17℃, -18℃, -19℃, and -20℃; the insulation time is 15~17h, including but not limited to 15h, 16h, and 17h; the temperature of the high-temperature stage is 55~65℃, including but not limited to 55℃, 58℃, 60℃, 62℃, 65℃, etc.; the insulation time is 22~26h, including but not limited to 22h, 23h, 24h, 25h, 26h, etc.; the number of cycles is 4~6, for example, it can be 4, 5, or 6 times.

[0028] More specifically, the temperature of the water immersion treatment is 20~30℃, including but not limited to 20℃, 22℃, 25℃, 28℃, 30℃, etc.; the time of the water immersion treatment is 2~3h, including but not limited to 2.2h, 2.4h, 2.6h, 2.8h, 3h, etc.

[0029] More specifically, the freeze-thaw splitting tensile strength ratio is calculated as: (2) Where: R T1 is the splitting tensile strength after freeze-thaw cycle treatment, MPa; R T2 is the splitting tensile strength after freeze-thaw cycles, MPa; TSR is the freeze-thaw splitting tensile strength ratio, %.

[0030] In this embodiment, for the same road performance, at least one of the fitting curves of road performance parameters and pH of different types of asphalt mixtures is a monotonically decreasing curve.

[0031] In this implementation, step S3 includes: S31, shifting the monotonically decreasing curve up and down to a coordinate point determined by the pH corresponding to a normal environment and a road performance index threshold of the asphalt mixture under the normal environment to obtain a shifted curve; S32, determining the road performance index threshold of the asphalt mixture in the alkaline water environment corresponding to the monotonically decreasing curve based on the pH and translation curve of the alkaline water environment; and, optionally, S33. Determine the road performance index threshold of the asphalt mixture in an alkaline water environment corresponding to the non-monotonic decreasing curve based on the road performance index threshold of the asphalt mixture in an alkaline water environment corresponding to the monotonically decreasing curve and the difference between the standard index.

[0032] In the present invention, in theory, the fitting curves of the road performance parameters and pH of asphalt mixtures in alkaline water environment are all monotonically decreasing curves. However, in the actual process, due to errors, some point values ​​may not conform to the theory. In this case, the corresponding road performance index thresholds of other asphalt mixtures can be determined based on the road performance index thresholds of one asphalt mixture in alkaline water environment and the standard index difference. For example, the standard deviation between ordinary asphalt mixtures and modified asphalt mixtures is 5.

[0033] In this embodiment, the pH value under normal conditions is 7.

[0034] In this implementation, step S4 includes: If the road performance parameter of the asphalt mixture is higher than the road performance index threshold of the asphalt mixture in the corresponding alkaline water environment, the performance of the asphalt mixture meets the requirements; If the road performance parameters of the asphalt mixture are lower than the road performance index threshold of the asphalt mixture in the corresponding alkaline water environment, the performance of the asphalt mixture does not meet the requirements.

[0035] Example 1 A method for evaluating the road performance of asphalt mixture in an alkaline water environment comprises the following steps: (1) Sample preparation: A typical graded AC-20C asphalt mixture type was selected to prepare Marshall specimens of 70# base asphalt mixture and SBS modified asphalt mixture for alkaline solution immersion test, as shown in Figures 2 and 3.

[0036] (2) Preparation of alkaline solution: Prepare 1L of NaOH solution with different pH values, as shown in Table 1. Place the prepared NaOH solution in a constant temperature and humidity curing box (temperature controlled at 25°C, relative humidity controlled at 50%) for 24h±0.5h. Measure the pH value again before use to ensure that the pH value is within the set value error of 0.2 before subsequent tests.

[0037] Table 1 NaOH solution preparation

[0038] (3) Marshall stability test of asphalt mixture in alkaline water environment: After the specimens are treated according to Table 2, the Marshall stability of the asphalt mixture is tested.

[0039] Table 2 Marshall specimen treatment

[0040] Each of the above tests uses 12 parallel specimens, divided into four groups. After obtaining the original test data, the residual stability after erosion by different solutions is calculated according to the residual stability formula (1). According to the above steps, the three tests of each group are averaged according to the test results, and the residual stability obtained is recorded in Table 3 and plotted as shown below. Figure 4 and 5 The line chart shown.

[0041] Table 3 Water-immersion residual stability of asphalt mixture (%)

[0042] (4) Residual strength ratio test of asphalt mixture freeze-thaw splitting test in alkaline water environment: After the specimens are treated according to Table 4, the splitting tensile strength of the asphalt mixture is tested.

[0043] Table 4 Marshall specimen treatment

[0044] Each of the above tests uses four parallel specimens. After obtaining the original test data (the original data are the splitting tensile strengths measured for the five groups of specimens above), the freeze-thaw splitting tensile strength ratio of the Marshall specimen is calculated according to formula (2). According to the above steps, the freeze-thaw splitting tensile strength ratio obtained from the test is recorded in Table 5 and plotted as follows: Figure 6 and 7 The line chart shown.

[0045] Table 5 Tensile strength ratio of asphalt mixture freeze-thaw splitting test (%)

[0046] (5) Determination of the threshold values ​​of macro-test indicators under alkaline water environment: Referring to the provisions of the Technical Specifications for Highway Asphalt Pavement Construction, the technical requirements for the water-immersion Marshall test indicator water-immersion residual stability and the freeze-thaw splitting test indicator tensile strength ratio are summarized in the table below.

[0047] Table 6 Macro test indicators and technical requirements

[0048] The data of the Marshall test and freeze-thaw cycle test results in alkaline water environment were fitted, as shown in Figures 8 to 11. The threshold values ​​of indicators in alkaline environments with different pH values ​​were established based on the equation established by the fitting results as a reference, as shown in the following table. In view of the fact that the test results of the residual stability of the modified asphalt mixture are very close at pH 12 and 14, resulting in a large error in the test results (the residual stability of immersion at pH 14 is higher than that at pH 12, and in theory, the alkaline environment has an inhibitory effect on the performance of the mixture and the stronger the alkalinity, the worse the performance, which is obviously contrary to the theory), the difference in the standard indicators is used to determine the threshold value of the modified asphalt mixture.

[0049] Table 7 Macro test index thresholds under alkaline water environment

[0050] It can be seen from Table 7 that the road performance index threshold of asphalt mixture in alkaline water environment can be obtained by the method of the present invention, so as to screen the materials used in the project according to whether the test results of asphalt mixture in alkaline environment meet the threshold requirements; and the tensile strength ratio thresholds of ordinary asphalt mixture and modified asphalt mixture determined by the method of the present invention are both near the standard index difference of 5 between ordinary asphalt mixture and modified asphalt mixture, which also illustrates the rationality of the method of the present invention.

[0051] Compared with the prior art, the beneficial effects of the present invention also include: (1) The treatment method of the present invention is helpful for analyzing the changing law of water stability of asphalt mixture in alkaline water environment. For example, the test results of Example 1 of the present invention show that as the pH value of the solution increases, the Marshall stability and splitting tensile strength of the asphalt mixture both show a downward trend, that is, the alkaline water environment will cause the water stability of the asphalt mixture to decrease. For the 70# matrix asphalt mixture, after being corroded by an alkaline solution with a pH value of 14, its Marshall stability decreased by 27.63% and its splitting tensile strength decreased by 30.57% compared with the dry environment; for the SBS modified asphalt mixture, after being corroded by an alkaline solution with a pH value of 14, its Marshall stability decreased by 24.4% and its splitting tensile strength decreased by 25.88% compared with the dry environment. It can be seen that compared with the Marshall stability of the asphalt mixture after being corroded by alkaline solution and distilled water, the attenuation amplitude of the splitting tensile strength of the asphalt mixture is greater, indicating that the freeze-thaw cycle will further aggravate the adverse effects of water molecules and alkaline solutions on the water stability of the asphalt mixture.

[0052] (2) The method of the present invention uses the macroscopic water stability test of asphalt mixture to analyze the change law of water stability of asphalt mixture caused by the failure of asphalt-aggregate interface adhesion in alkaline water environment, which makes up for the deficiency of existing research on the influence of alkaline solution on asphalt mixture, and provides a basis for preventing and reducing the new form of water damage of asphalt pavement whitening disease.

[0053] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for evaluating the road performance of asphalt mixture in an alkaline water environment, characterized in that: The following steps are involved: S1. Obtaining road performance parameters of asphalt mixture in alkaline water environment; S2. Establishing a fitting curve between the road performance parameters and pH of the asphalt mixture in the alkaline water environment; S3. Based on the fitting curve and the road performance index threshold of the asphalt mixture under normal environment, obtain the road performance index threshold of the asphalt mixture under alkaline water environment; S4. Evaluate the road performance of the asphalt mixture based on the road performance index threshold of the asphalt mixture in the alkaline water environment.

2. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 1, characterized in that: The pH of the alkaline water environment is 8-14.

3. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 1, characterized in that: The asphalt mixture includes ordinary asphalt mixture and / or modified asphalt mixture.

4. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 1, characterized in that: Step S1 includes: S11, providing an asphalt mixture and an alkaline solution with different pH values; S12, corroding the asphalt mixture by using the alkaline solutions with different pH values, and performing a road performance test on the asphalt mixture after the corroding treatment to obtain road performance parameters of the asphalt mixture in an alkaline water environment.

5. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 4, characterized in that: The alkaline solution is at least one of a sodium hydroxide solution, a potassium hydroxide solution or a calcium hydroxide solution.

6. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 4, characterized in that: The road performance is the residual stability of water immersion, and step S12 includes: The asphalt mixture is subjected to alkali leaching treatment by using the alkaline solutions with different pH values, and then the asphalt mixture subjected to the alkali leaching treatment is subjected to water leaching treatment, and then the asphalt mixture subjected to the water leaching treatment is subjected to a stability test to obtain the stability after the alkali leaching treatment; The asphalt mixture is subjected to water immersion treatment, and then the stability of the asphalt mixture after the water immersion treatment is tested to obtain the stability after the asphalt mixture is not subjected to alkali immersion treatment; A calculation formula for the residual stability after immersion is established, and the residual stability after immersion is obtained based on the stability after alkali immersion treatment and the stability after not alkali immersion treatment; wherein, The alkali leaching treatment temperature is 20-30°C, and the alkali leaching treatment time is 6-8 days; The water immersion treatment temperature is 55-65°C, and the water immersion treatment time is 30-40 minutes; The calculation formula of the water immersion residual stability is: （1） Where: MS is the stability without alkali leaching treatment, kN; MS1 is the stability after alkali leaching treatment, kN; MS0 is the residual stability after immersion in water, %.

7. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 4, characterized in that: The road performance is the freeze-thaw splitting tensile strength ratio, and step S12 includes: The asphalt mixture is subjected to freeze-thaw cycle treatment by using the alkaline solutions with different pH values, and then the asphalt mixture subjected to the freeze-thaw cycle treatment is subjected to water immersion treatment, and then the asphalt mixture subjected to the water immersion treatment is subjected to a splitting tensile strength test to obtain the splitting tensile strength after the freeze-thaw cycle treatment; Performing water immersion treatment on the asphalt mixture, and then performing a splitting tensile strength test on the asphalt mixture after the water immersion treatment to obtain the splitting tensile strength after not being subjected to freeze-thaw cycle treatment; A calculation formula for the freeze-thaw splitting tensile strength ratio is established, and the freeze-thaw splitting tensile strength ratio is obtained based on the splitting tensile strength after the freeze-thaw cycle treatment and the splitting tensile strength after the freeze-thaw cycle treatment; wherein, During the freeze-thaw cycle treatment, the temperature of the low temperature stage is -16~-20°C, and the insulation time is 15~17h; the temperature of the high temperature stage is 55~65°C, and the insulation time is 22~26h; the number of cycles is 4~6; The temperature of the water immersion treatment is 20-30°C, and the time of the water immersion treatment is 2-3h; The calculation formula of the freeze-thaw splitting tensile strength ratio is: （2） Where: R T1 is the splitting tensile strength after freeze-thaw cycle treatment, MPa; R T2 is the splitting tensile strength after freeze-thaw cycles, MPa; TSR is the freeze-thaw splitting tensile strength ratio, %.

8. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 1, characterized in that: For the same road performance, at least one of the fitting curves of the road performance parameters and pH of different types of asphalt mixtures is a monotonically decreasing curve, and step S3 includes: The monotonically decreasing curve is translated up and down to a coordinate point determined by a pH value corresponding to a normal environment and a road performance index threshold value of an asphalt mixture under a normal environment, to obtain a translation curve; Determine the road performance index threshold of the asphalt mixture in the alkaline water environment corresponding to the monotonically decreasing curve based on the pH of the alkaline water environment and the translation curve; and, optionally, The road performance index threshold of the asphalt mixture in an alkaline water environment corresponding to the non-monotonic decreasing curve is determined based on the road performance index threshold of the asphalt mixture in an alkaline water environment corresponding to the monotonically decreasing curve and the difference between the standard index.

9. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 1, characterized in that: The pH under the normal environment is 7.

10. The method for evaluating the road performance of asphalt mixture in an alkaline water environment according to claim 1, characterized in that: Step S4 includes: If the road performance parameter of the asphalt mixture is higher than the road performance index threshold of the asphalt mixture in the corresponding alkaline water environment, the performance of the asphalt mixture meets the requirements; If the road performance parameter of the asphalt mixture is lower than the road performance index threshold of the asphalt mixture in the corresponding alkaline water environment, the performance of the asphalt mixture does not meet the requirements.

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