Compound amine anti-stripping agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of road construction materials, and relates to a compound amine anti-stripping agent as well as a preparation method and application thereof. The compound amine anti-stripping agent comprises polyamide resin and sodium dodecyl benzene sulfonate; the mass fraction of the polyamide resin is 70%-85%, and the mass fraction of the sodium dodecyl benzene sulfonate is 15%-30%. According to the compound amine anti-stripping agent disclosed by the invention, the high and low temperature stability and the anti-fatigue performance of an asphalt mixture are enhanced through double synergy of a chemical bonding effect and an adsorption effect, and the compound amine anti-stripping agent has remarkable anti-stripping performance.

Description

Technical Field

[0001] This invention belongs to the field of road construction materials technology, and relates to a composite amine anti-stripping agent, its preparation method and application. Background Technology

[0002] Asphalt pavement is widely used on high-grade highways due to its advantages such as good smoothness, driving comfort, excellent workability, and ease of repair. However, with the increasing traffic volume and serious overloading and speeding problems, coupled with the high temperature sensitivity of asphalt pavement, many asphalt pavements have suffered water damage such as peeling and potholes under high humidity and rainwater erosion. This leads to a shortened service life of the pavement, prematurely entering the maintenance period, and increasing the cost of pavement maintenance. Therefore, improving the water stability of asphalt mixtures is crucial.

[0003] To address the problem of water damage to asphalt pavements, adding anti-stripping agents to asphalt mixtures is an effective way to improve the bonding performance of asphalt and has been widely used in practical engineering. This is because the addition of anti-stripping agents causes physical adsorption or chemical bonding between asphalt and aggregates, reducing the interfacial tension between asphalt and aggregates, thereby improving the adhesion between asphalt and aggregates and enhancing the water resistance of asphalt pavements.

[0004] The following are some commonly used anti-stripping agents in building construction: The first type is inorganic anti-stripping agents. For example, see CN106186778B, "Anti-stripping Agent for Road Petroleum Asphalt and its Preparation Method," which uses lime as an anti-stripping agent to increase the content of alkaline components on the aggregate surface, thereby improving anti-stripping ability through acid-base chemical action. This type of anti-stripping agent is characterized by low cost and excellent performance, but its application process is complex, it is difficult to mix evenly, affecting the durability of the mixture and resulting in poor high and low temperature stability.

[0005] The second type is metal saponification, see CN104479373A "Anti-stripping Highway Asphalt and its Preparation Method", which uses iron soap as an anti-stripping agent to modify asphalt, improve asphalt performance and thus enhance its anti-stripping ability. This type is convenient to use and low in cost, but because of its large density difference with asphalt, it is prone to segregation, leading to a decrease in anti-stripping performance.

[0006] The third type is surfactants, such as quaternary ammonium salts, which can modify asphalt and are easy to use; however, they are more expensive and the modified asphalt mixture has poor thermal stability.

[0007] In conclusion, given the existing anti-stripping agents' poor anti-stripping properties and poor high and low temperature stability in asphalt modification, it is urgent to develop a new type of anti-stripping agent. Summary of the Invention

[0008] To address the problems of poor anti-stripping properties and poor high and low temperature stability of existing anti-stripping agents in asphalt mixture modification, this invention provides a composite amine anti-stripping agent, its preparation method, and its application.

[0009] This invention mixes polyamide resin and sodium dodecylbenzenesulfonate in a specific ratio to form a composite amine anti-stripping agent. Through the synergistic effect of chemical bonding and adsorption, it enhances the high and low temperature stability and fatigue resistance of asphalt mixtures, and has significant anti-stripping properties.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A composite amine anti-stripping agent comprises a polyamide resin and sodium dodecylbenzene sulfonate; wherein the polyamide resin has a mass fraction of 70% to 85% and the sodium dodecylbenzene sulfonate has a mass fraction of 15% to 30%.

[0011] Further specifying, the polyamide resin has a mass fraction of 80%-85%, and the sodium dodecylbenzenesulfonate has a mass fraction of 15%-20%.

[0012] A method for preparing a composite amine anti-stripping agent includes the following steps: S1. Weigh out the polyamide resin and sodium dodecylbenzene sulfonate according to their mass fractions; S2. Heat the polyamide resin to a fluid state; then add sodium dodecylbenzenesulfonate, and thoroughly shear and stir until evenly dispersed; finally, cool to obtain the final product.

[0013] Further specifying that in step S2, the heating temperature is 150±5℃, the shearing speed is 1000r / min-1200r / min, and the stirring time is 10min-15min.

[0014] The application of the composite amine anti-stripping agent in improving the adhesion between asphalt and aggregate.

[0015] The application of the aforementioned composite amine anti-stripping agent in improving the high-temperature stability of asphalt.

[0016] The application of the aforementioned composite amine anti-stripping agent in improving the low-temperature stability of asphalt.

[0017] Furthermore, when applying the compound amine anti-stripping agent, the amount added is 0.3%-0.5% of the mass of the asphalt.

[0018] Further specifying the application method, the composite amine anti-stripping agent is added to asphalt, and modified by shearing and stirring to obtain modified asphalt; the modification temperature is 175±5℃, the shearing speed is 3000r / min-3200r / min, and the stirring time is 50min-55min.

[0019] Compared with the prior art, the beneficial effects of the present invention are: The composite amine anti-stripping agent of this invention comprises two low-molecular-weight components: polyamide resin and sodium dodecylbenzene sulfonate. Polyamide resin is an amber-colored viscous liquid containing polar groups, capable of forming hydrogen bonds or ionic bonds with acidic components in asphalt and the negatively charged aggregate surface. This chemical bonding enhances the polarity of the asphalt, thereby improving the adhesion between asphalt and aggregate. Sodium dodecylbenzene sulfonate is a surfactant; its addition to asphalt allows some asphalt to be adsorbed onto the surfactant surface, while some is directly adsorbed onto the aggregate, promoting adsorption between the aggregate and asphalt. The two low-molecular-weight components, polyamide resin and sodium dodecylbenzene sulfonate, complement each other. Through the synergistic effect of chemical bonding and adsorption, they improve the compatibility between asphalt and aggregate surfaces, further enhancing the adhesion between asphalt and aggregate and improving the anti-stripping ability of the asphalt mixture. Simultaneously, they strengthen the stability of the anti-stripping agent in asphalt, especially its high-temperature and low-temperature stability and fatigue resistance, allowing the anti-stripping agent to achieve its optimal effect. Attached Figure Description

[0020] Figure 1 The results are the rutting factor-temperature scan, where: (left) is No. 70 asphalt, and (right) is No. 90 asphalt; Figure 2 The damage characteristic curves (D-C curves) are based on dissipated energy, where: (a) is No. 70 asphalt, and (b) is No. 90 asphalt; Figure 3 The images are infrared spectra, where (a) is No. 70 asphalt and (b) is No. 90 asphalt. Figure 4 Fluorescence micrographs of No. 70 and No. 90 asphalt before and after aging with different dosages of anti-stripping agent (from left to right: 0%, 0.3%, 0.4%, 0.5%). Figure 5 The results are NMR results of No. 70 asphalt with different anti-stripping agent dosages. (a) is No. 70 asphalt with 0% dosage, (b) is No. 70 asphalt with 0.4% dosage before aging, and (c) is No. 70 asphalt with 0.4% dosage after aging. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] The present invention provides a composite amine anti-stripping agent comprising polyamide resin and sodium dodecylbenzene sulfonate; wherein the polyamide resin has a mass fraction of 70% to 85% and the sodium dodecylbenzene sulfonate has a mass fraction of 15% to 30%.

[0023] Preferably, the polyamide resin has a mass fraction of 80%-85%, and the sodium dodecylbenzenesulfonate has a mass fraction of 15%-20%.

[0024] This invention also provides a method for preparing a composite amine anti-stripping agent, comprising the following steps: S1. Weigh out the polyamide resin and sodium dodecylbenzene sulfonate according to their mass fractions; S2. Heat the polyamide resin to a fluid state; then add sodium dodecylbenzenesulfonate, and thoroughly shear and stir until evenly dispersed; finally, cool to obtain the final product.

[0025] Preferably, in step S2, the heating temperature is 150±5℃, the shearing speed is 1000r / min-1200r / min, and the stirring time is 10min-15min.

[0026] The composite amine anti-stripping agent provided by this invention, after modifying asphalt, not only improves the asphalt-aggregate adhesion performance but also enhances the high-temperature stability, low-temperature stability, and fatigue resistance of asphalt, thereby strengthening the anti-stripping performance of asphalt pavement materials. In application, modified asphalt is obtained by modifying asphalt with the composite amine anti-stripping agent. Preferably, the amount of composite amine anti-stripping agent added is 0.3%-0.5% of the asphalt mass; preferably, the modification is carried out at a temperature of 175±5℃, by adding the composite amine anti-stripping agent to the asphalt, and then shearing and stirring until uniform to obtain modified asphalt. The shearing speed is 3000r / min-3200r / min, and the stirring time is 50min-55min.

[0027] The above-mentioned solution of the present invention will be described in detail through the following embodiments, and the anti-stripping performance of asphalt by composite amine anti-stripping agent will be studied through experiments.

[0028] In the following examples, the asphalt used was HY70 and HY90 asphalt produced by Shandong Jingbo Petrochemical. Basic performance tests were conducted according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The test results of the technical parameters of HY70 and HY90 asphalt are shown in Tables 1 and 2 below.

[0029] Table 1 Main Technical Parameters of HY70 Asphalt Table 2 Main Technical Parameters of HY90 Asphalt Limestone, basalt, and granite are three common aggregates used in asphalt mixtures. Limestone is an alkaline aggregate, basalt is a neutral to weakly alkaline aggregate, and granite is an acidic aggregate. Due to their different mineral compositions and surface properties, they exhibit significant differences in asphalt adhesion. Therefore, in the following examples, limestone, basalt, and granite were selected as the test materials. All three types of aggregates were obtained from the Lingshou County Mineral Products Processing Plant in Shijiazhuang, Hebei Province. Tests were conducted according to the conventional indicators in the "Specifications for Testing Aggregates in Highway Engineering" (JTG E42-2005), and the numerical ranges of the indicators in the "Technical Specifications for Construction of Asphalt Pavement on Highways" (JTG F40-2004) were referenced to evaluate whether the various related properties of the aggregates met the standards. The test results are shown in Table 3 below.

[0030] Table 3. Test results of three types of aggregates. It should be noted that, unless otherwise specified, all other reagents and medicines in the following embodiments are commercially available products purchased from the market; and the operations or testing methods in the following embodiments, unless otherwise specified, are all conventional methods in the field or industry.

[0031] Examples 1 to 5 In this embodiment, the composite amine anti-stripping agent includes polyamide resin (PA) and sodium dodecylbenzene sulfonate (SDBS), and the mass ratio of polyamide resin and sodium dodecylbenzene sulfonate is shown in Table 4.

[0032] Table 4. Formulation Design Scheme of Novel Anti-stripping Agent (Unit: g) The method for preparing the composite amine anti-stripping agent provided in this embodiment includes the following steps: S1. Weigh out the standard amounts of polyamide resin and sodium dodecylbenzene sulfonate using a balance according to the mass ratio. S2. Heat the polyamide resin to a fluid state, place it in a high-speed shearing machine, add sodium dodecylbenzene sulfonate at high temperature, and shear and stir thoroughly until sodium dodecylbenzene sulfonate is evenly dispersed in the polyamide resin. Specifically, the polyamide resin is heated to a fully fluid state in a 150℃ oven, then placed in a 150℃ oil bath. The appropriate mass of sodium dodecylbenzenesulfonate is then uniformly added using a high-speed shear mixer under stirring at 1000 rpm. After complete addition, the mixture is continuously stirred at 150℃ for 10 minutes to ensure uniform dispersion of the sodium dodecylbenzenesulfonate in the polyamide resin.

[0033] S3. After cooling, the composite amine anti-stripping agents are obtained and are successively labeled as D-1, D-2, D-3, D-4, and D-5.

[0034] Verification Example 1 This verification example mainly uses the composite amine anti-stripping agent (hereinafter referred to as anti-stripping agent) of Examples 1-5 to modify asphalt and studies the adhesion properties of the modified asphalt. At the same time, pure asphalt is used as the blank group, and two commercially available anti-stripping agents, amine and non-amine, are used as control groups. The non-amine anti-stripping agent is designated as control group 1, and the amine anti-stripping agent is designated as control group 2.

[0035] 1.1 The asphalt adhesion grade was determined using the boiling water method. The specific method is as follows: Five equal parts of asphalt (HY70 asphalt / or HY90 asphalt) are placed in an oven at 150℃ and heated for 1 hour; according to the anti-stripping agent addition amount of 0.4% of the asphalt mass, the anti-stripping agents of Examples 1-5 are added to the heated asphalt for pre-modification for 30 minutes; shearing modification is carried out for 50 minutes at a high-speed shearing machine speed of 3000 r / min and an oil bath temperature of 175℃ to obtain five kinds of modified asphalt. Granite, limestone, and basalt are used as aggregates, and cubic coarse aggregates with a particle size of 13mm~19mm are selected, washed and dried. Each type of modified asphalt was divided into 3 parts. Each of the 3 types of aggregates was immersed in the 5 types of modified asphalt heated to 130~150℃ for 45 seconds to ensure that the aggregates were completely coated by the modified asphalt. The prepared samples were suspended vertically to allow the excess asphalt to drip freely. After cooling to room temperature, they were immersed in slightly boiling water for 3 minutes. After being removed, they were placed in warm water to observe the asphalt film peeling area. The adhesion grade was evaluated according to the 5-level standard (1 = aggregates are basically completely exposed, 5 = asphalt film is basically completely covered). The results are shown in Table 5 below.

[0036] Following the same method described above, two commercial anti-stripping agents and pure base asphalt were used as controls. The results are shown in Table 5 below.

[0037] Table 5 Comparison of Adhesion Grades The experimental results show that when the mass fraction of polyamide resin is 70%~85% and the mass fraction of sodium dodecylbenzenesulfonate is 15%~30%, the adhesion grade between the anti-stripping agent-modified asphalt and aggregates is comparable to or higher than that of commercially available anti-stripping agents. This indicates that the composite amine anti-stripping agent prepared in this invention has significant adhesion properties.

[0038] 1.2. The photoelectric colorimetric method was used to examine the adhesion grade of asphalt. Modified asphalt from Example 2, Example 3, and Example 4, selected by the boiling water method for high adhesion properties, as well as pure asphalt, were analyzed using phenolic saffron red as a dye solution and limestone as aggregate. The adhesion between the aggregate and asphalt (or modified asphalt) was quantitatively analyzed by photoelectric colorimetry to quantify the improvement in asphalt-aggregate adhesion. The results are shown in Table 6. Two commercial anti-stripping agents were used as controls. The results are shown in Table 6 below.

[0039] Table 6. Results of photoelectric colorimetric tests on different anti-stripping agents Table 6 shows that the anti-stripping performance of the composite amine anti-stripping agents in Examples 2, 3, and 4 is higher than that of the two commercially available anti-stripping agents. This indicates that the composite amine anti-stripping agent provided in this example exhibits high adhesion and anti-stripping performance to asphalt-limestone aggregates.

[0040] The results from the boiling water method and photoelectric colorimetric method show that the synergistic effect of polyamide resin and sodium dodecylbenzene sulfonate in this invention improves the adhesion grade and adhesion properties of asphalt, indicating that it has good anti-stripping properties. Furthermore, the results also show that Example 3 has the most significant effect; after modification with the anti-stripping agent of Example 3, the adhesion properties between the modified asphalt and aggregates reach their optimal level. Therefore, the formulation of Example 3 is the optimal formulation for a composite amine anti-stripping agent.

[0041] Verification Example 2 This verification example mainly utilizes the composite amine anti-stripping agent (hereinafter referred to as anti-stripping agent) from Example 3 to modify asphalt, thereby improving the performance of asphalt.

[0042] Sample preparation: The anti-stripping agent of Example 3 was added to asphalt at 0.3%, 0.4%, and 0.5% of the asphalt mass, respectively, to modify the asphalt. Modified asphalts with different dosages were prepared according to the method of Verification Example 1. The asphalts were HY70 and HY90 asphalt, respectively.

[0043] Referring to JTG E20—2019 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", penetration, softening point and ductility tests were conducted on modified asphalt to study the effect of dosage changes on the performance of modified asphalt.

[0044] 2.1 Needle penetration According to standard T0604-201X, the penetration index test conditions are as follows: constant temperature 25℃, standard needle load 100g, penetration time 5s, and the depth to which the standard needle vertically penetrates the asphalt sample is measured. The unit of penetration is 0.1mm. Specifically, the asphalt is heated to a fluid state and then placed in a specific flat-bottomed container, cooled to room temperature, and maintained at a constant temperature of 25°C. A penetration meter is used; the standard needle is placed on the asphalt surface, released, and allowed to penetrate vertically for 5 seconds, recording the penetration depth. Three parallel tests are performed simultaneously to reduce test error. The penetration test results are shown in Table 7 below.

[0045] Table 7. Penetration of modified asphalt with different amounts of anti-stripping agent Table 7 shows that the penetration decreases with increasing anti-stripping agent dosage, indicating that the addition of anti-stripping agent can improve asphalt viscosity. For HY70 asphalt, increasing the anti-stripping agent dosage from 0.3% to 0.4% resulted in a 2.6% decrease in penetration; increasing it from 0.4% to 0.5% resulted in a 2.3% decrease. For HY90 asphalt, increasing the anti-stripping agent dosage from 0.3% to 0.4% resulted in a 1.0% decrease in penetration; increasing it from 0.4% to 0.5% resulted in a 0.7% decrease. After the anti-stripping agent dosage reaches 0.4%, the rate of decrease in asphalt penetration slows down, and the efficiency of improving asphalt viscosity decreases.

[0046] 2.2 Softening point The ring and ball method was used as the testing method. A softening point tester was used, and modified asphalt was heated to a fluid state and injected into a copper sample ring. After cooling, the surface was smoothed. The sample ring, along with a metal support, a steel ball, and a steel ball positioner, was simultaneously placed in 5°C water and kept at a constant temperature for at least 15 minutes. According to the T0606-201X standard, the initial temperature of the softening point test was 25°C, and the heating rate was 5°C / min. The temperature at which the steel ball reached the bottom of the asphalt ring was recorded. Two parallel tests were conducted under the same conditions to ensure that the test error was within ±0.5°C. The softening point test results are shown in Table 8.

[0047] Table 8 Softening points of asphalt modified with different amounts of anti-stripping agent Table 8 shows that for HY70 asphalt, increasing the anti-stripping agent dosage from 0.3% to 0.4% increased the softening point by 2.3%; increasing it from 0.4% to 0.5% increased it by 1.1%. For HY90 asphalt, increasing the anti-stripping agent dosage from 0.3% to 0.4% increased the softening point by 1.3%; increasing it from 0.4% to 0.5% increased it by 0.9%. The softening point increases with increasing anti-stripping agent dosage, indicating that the addition of the anti-stripping agent significantly improves the high-temperature performance of asphalt.

[0048] 2.3, Ductility The uniformly mixed release agent was applied to the inside of the mold. The asphalt was heated and melted, then poured into the mold. After cooling, the mold was removed from the water bath and fixed to the ductility tester fixture. According to standard T0605-201X, the ductility tester was used at a test temperature of 15℃ and a tensile speed of 5 cm / min. The test measured the maximum length of the asphalt sample stretched until fracture. The ductility test results showed that at 15℃, the addition of the anti-stripping agent maintained the asphalt ductility at >100 cm, ensuring the flexibility and plasticity of the asphalt.

[0049] 2.4 Brinell viscosity The Brinell rotational viscosity test was conducted primarily according to JTG E20—2019 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The testing instrument was a Brookfield DV2TRV Brinell rotational viscometer from the USA, using a No. 27 rotor. Test temperatures of 115℃, 135℃, 155℃, and 175℃ were selected to measure the resistance of asphalt to rotor rotation, reflecting the influence of different amounts of anti-stripping agent on the Brinell viscosity of asphalt.

[0050] The results of the Brookfield viscosity tests at different temperatures for modified asphalt with different amounts of anti-stripping agents are shown in Table 9 below.

[0051] Table 9. Brinell viscosity of asphalt modified with different amounts of anti-stripping agent As can be seen from Table 9, compared with the Brinell viscosity of asphalt, the Brinell viscosity of asphalt modified with different dosages of anti-stripping agent is significantly improved, and the increase is greater at 0.4% dosage than at 0.5% dosage. This phenomenon is more significant at 115℃, indicating that the anti-stripping agent has a better modification effect at 0.4% dosage.

[0052] Studies on the penetration, softening point, ductility, and Brinell viscosity of asphalt modified with anti-stripping agent at different dosages revealed that as the anti-stripping agent dosage increased, the penetration of the modified asphalt decreased, the softening point increased, the ductility exceeded 100, and the Brinell viscosity increased. Preferably, a dosage of 0.4% anti-stripping agent yielded good results; further increases in the dosage resulted in less significant modification effects. Therefore, the optimal dosage of anti-stripping agent was determined to be 0.4%.

[0053] Verification Example 3 This verification example mainly examines the effect of compound amine anti-stripping agents (hereinafter referred to as anti-stripping agents) on the performance of modified asphalt road surfaces.

[0054] 3.1 High-temperature rutting resistance The high-temperature performance of modified asphalt was tested. The main evaluation indicators of the high-temperature performance of asphalt include softening point, dynamic viscosity, rutting factor, zero shear viscosity, critical temperature, and creep recovery rate. The high-temperature performance of modified asphalt was studied by temperature scanning test using a DSR dynamic shear rheometer.

[0055] To investigate the high-temperature performance of modified asphalt under different temperature conditions, modified asphalt at various dosages was obtained by referring to the method in Verification Example 2. The DSR temperature scanning mode was used to perform temperature scanning on the modified asphalt at each dosage. The test parameters were set as follows: (1) the diameter of the test loading plate was 25 mm, and the gap between the plates was 1 mm; (2) the frequency was 10 rad / s, and the strain was 10%. Temperature scanning tests were conducted on the asphalt at 4℃ intervals within the range of 46℃-80℃. The rutting factor was used as the high-temperature performance evaluation index. The temperature scanning results are shown in […]. Figure 1 As shown.

[0056] Depend on Figure 1 It can be seen that the rutting factor decreases with increasing temperature, while the rutting factor gradually increases with increasing anti-stripping agent dosage, indicating that the addition of anti-stripping agent effectively improves the high-temperature performance of asphalt. The rutting factor of modified asphalt with 0.4% and 0.5% dosages does not increase significantly, indicating that the anti-stripping agent dosage of 0.4% has the best effect on improving the high-temperature performance of asphalt.

[0057] 3.2 Intermediate Temperature Fatigue Performance The anti-stripping agent of Example 3 was incorporated into asphalt at 0.3%, 0.4%, and 0.5% of the asphalt mass, respectively, and the asphalt's mid-temperature fatigue performance was then evaluated.

[0058] Specifically, asphalt pressure aging (PAV) tests were conducted on modified asphalt with different admixtures. According to the JTG E20-T0630 test procedure, asphalt and modified asphalt samples were placed in the equipment and subjected to short-term aging and long-term aging in sequence, and then their damage characteristic curves were measured.

[0059] Figure 2 The damage characteristic curves (DCC) are based on dissipated energy. The higher and to the right the curve is, the higher the integrity and the slower the stiffness decay under the same damage level, indicating stronger damage resistance. Compared to 0.3%, the 0.4% curve shifts upward more significantly and has a smaller initial slope, indicating reduced early damage sensitivity and stronger damage resistance; while the 0.5% curve continues to shift to the right, the gain is limited. Furthermore, the fatigue life N is calculated based on the modulus reduction criterion. f The results are shown in Table 10.

[0060] At a strain of 2.5%, the fatigue life of HY70 asphalt increased by 7.5%, 9.5%, and 10.2% at dosages of 0.3%, 0.4%, and 0.5%, respectively; for HY90 asphalt, the increases were 7.6%, 10.2%, and 10.8%, respectively. At a strain of 5%, the fatigue life of HY70 asphalt increased by 7.5%, 9.5%, and 10.2% at dosages of 0.3%, 0.4%, and 0.5%, respectively; for HY90 asphalt, the increases were 7.6%, 10.2%, and 10.8%, respectively. This indicates a synergistic improvement in intermediate-temperature fatigue life and damage resistance. However, the gain effect is limited when the dosage increases from 0.4% to 0.5%. Considering both performance improvement and engineering economics, 0.4% is recommended as the preferred dosage for composite amine anti-stripping agents.

[0061] Table 10 Fatigue life calculation results 3.3 Low-temperature crack resistance stability The main evaluation indicators for the low-temperature performance of asphalt include equivalent brittle point, ductility, and stiffness modulus. The low-temperature performance of modified asphalt was studied by using a BBR bending rheometer to conduct bending creep tests.

[0062] According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering," asphalt samples must be treated with short-term aging and long-term pressure aging in a rotating thin-film oven before testing with a BBR (Biological Stiffness Modulation) tester. This aims to simulate the actual aging conditions of hot-mix asphalt mixtures during construction and after use. Following the JTG E20-T0630 test procedure, asphalt and modified asphalt samples are placed in the equipment and subjected to short-term and long-term aging sequentially. In the BBR test, three temperatures are set: -12℃, -18℃, and -24℃, to obtain the critical temperature T for the creep stiffness modulus. Ls (Temperature corresponding to S = 300 MPa) and the critical temperature T for creep rate Lm (Temperature corresponding to m = 0.3), final temperature T Lc =max(T) Ls T Lm The regression results are shown in Table 11 below.

[0063] Table 11 Calculation Table of Low Temperature Critical Temperature The results show that the creep stiffness of each type of asphalt increases with decreasing temperature. The creep stiffness modulus of each asphalt at -18℃ and -12℃ meets the requirement of not exceeding 300MPa, indicating that the modified asphalt has good overall low-temperature performance. At a constant temperature, the creep stiffness modulus of asphalt increases partially with the addition of anti-stripping agent, while the creep rate decreases. This indicates that the addition of anti-stripping agent has a positive effect on the strain relaxation ability of modified asphalt, mainly because the anti-stripping agent absorbs the lightweight components in the asphalt, increasing the viscous components and thus increasing the deformation capacity of the asphalt at low temperatures. Taking HY70 asphalt as an example, compared to pure asphalt, the low-temperature critical temperature of asphalt decreased by 2.1% after adding 0.3% anti-stripping agent; and by 4.0% after adding 0.5% anti-stripping agent. Therefore, the addition of anti-stripping agent lowers the low-temperature critical temperature of asphalt and improves its low-temperature stability.

[0064] 4. Microscopic and Mechanistic Analysis 4.1 Fourier Transform Infrared Spectroscopy Experiment To study the microstructure of asphalt, a Fourier transform infrared (FTIR) spectrometer was used. HY70 and HY90 asphalts with a 0.4 wt% anti-stripping agent were selected and subjected to FTIR scans before and after modification and aging. The changes in the absorption peaks of the main functional groups in the modified asphalts before and after aging were compared and analyzed using FTIR spectroscopy. PAV aging of the asphalt was carried out according to the JTG E20-T0630 test procedure, involving carbonyl and sulfoxide functional groups.

[0065] After infrared scanning, the obtained test data is imported into the OMNIC software, with the test spectrum range selected as 400-4000 cm⁻¹. -1 After baseline adjustment and smoothing, the data was exported to obtain the infrared spectrum of each type of asphalt, as shown below. Figure 3 As shown.

[0066] Depend on Figure 3 It can be seen that under the same aging conditions, modified asphalt with different amounts of anti-stripping agent added has relatively small differences in its infrared spectrum, mainly exhibiting the following characteristic peaks: 2919 cm⁻¹ -1 The absorption peak at 2852 cm⁻¹ is enhanced, mainly due to the stretching vibration of the CH bond in aliphatic methyl groups; -1 The absorption peak at 1455 cm⁻¹ is enhanced, mainly due to the stretching vibration of the CH bond in the methylene group; -1 The enhanced absorption peak at 1373 cm⁻¹ is mainly due to the stretching vibration of CH in the methyl and methylene groups of alkane hydrocarbons. -1 The absorption peak at 1261 cm⁻¹ is enhanced, mainly due to the methyl scissor vibration; -1 The absorption peak at 1692 cm⁻¹ is enhanced, mainly due to the CO stretching vibration; -1The absorption peak is enhanced at 1030 cm⁻¹, mainly due to the carbonyl C=O group; -1 The enhanced absorption peak at 910-650 cm⁻¹ is mainly due to the S=O stretching vibration of the sulfoxide group. -1 The absorption peak is enhanced, mainly due to the out-of-plane rocking vibration of the CH group of the benzene ring. It can be seen that the positions of the characteristic absorption peaks are basically the same before and after the addition of the anti-stripping agent, while the intensity of the absorption peaks differs slightly, indicating that no chemical reaction occurs between the anti-stripping agent and the asphalt, only a physical blending process. After the modified asphalt has undergone PAV aging, the peak intensity at 1692 cm⁻¹ is significantly higher. -1 carbonyl group and 1030 cm -1 The increase in sulfoxide groups indicates that the modified asphalt underwent an oxidation reaction after PAV aging, resulting in an increase in oxygen-containing functional groups. To further quantify the aging indicators, the absorption peak area index of carbonyl and sulfoxide groups was selected as evaluation indicators to quantitatively describe the impact of anti-stripping agent addition on the aging characteristics of asphalt, thereby achieving a quantitative assessment of the degree of asphalt aging.

[0067] The present invention uses OMNIC software to test the infrared spectral area of ​​a specific region and calculates the carbonyl index and sulfoxide index according to the following formulas (1) and (2). The calculation results are shown in Table 12 below.

[0068] In the above formula: Carbonyl index; sulfoxide index; A 1700 The infrared spectral area at a wavelength of 1700 nm. A 1460 The infrared spectral area at a wavelength of 1460 nm. A 1375 The infrared spectral area at a wavelength of 1375 nm. A 1030 It represents the infrared spectral area at a wavelength of 1030 nm.

[0069] Table 12 Infrared characteristic peaks of asphalt under different conditions As shown in Table 12 above, the carbonyl index and sulfoxide index show an increasing trend during the aging process. This is mainly because asphalt aging is essentially an oxidation reaction, where carbon bonds are broken and combine with oxygen to form carbonyl groups; sulfur in the asphalt combines with oxygen to form sulfoxide groups. The carbonyl index and sulfoxide index of HY70 asphalt increased by 26.7% and 63.8% respectively during the PAV aging stage. The carbonyl index and sulfoxide index of HY70 asphalt -0.4% increased by 32.0% and 71.3% respectively during the PAV aging stage. Without aging, the carbonyl index and sulfoxide index of HY70 asphalt -0.4% increased by -18.0% and -9.90% respectively compared to the original asphalt. The carbonyl index and sulfoxide index of HY90 asphalt increased by 14.9% and 26.1% respectively during the PAV aging stage. During the PAV aging stage, the carbonyl index and sulfoxide index of HY90 asphalt-0.4% increased by 18.3% and 25.5%, respectively. In the unaged state, the carbonyl index and sulfoxide index of HY90 asphalt-0.4% increased by -16.0% and -9.91% compared to the original asphalt, respectively. In summary, the addition of the anti-stripping agent enhances the anti-aging ability of asphalt, indicating that its addition can slow down the oxidation of asphalt, thereby slowing down the hardening of the asphalt structure, reducing embrittlement, and maintaining stress relaxation ability, thus reducing the risk of low-temperature cracking and fatigue damage. Simultaneously, it can delay the evolution of asphalt components and interface deterioration, weaken the competitive adsorption and displacement effect of water at the interface, and make the interface adhesion more stable, which helps maintain the long-term effectiveness of the modified asphalt structure.

[0070] 4.2 Fluorescence Microscopy Experiment The microstructure characteristics of modified asphalt were studied using an LW300LFT-LED fluorescence microscope. The samples were prepared by hot drop cover glass molding method. The test samples and equipment were also examined.

[0071] (1) Fluorescence scanning was performed on HY70 and HY90 asphalt with different admixtures before aging, and their microscopic images were obtained as follows: Figure 4 As shown.

[0072] Depend on Figure 4 It is evident that without the addition of an anti-stripping agent, the image appears black because the asphalt does not luminescent. With the addition of the anti-stripping agent, due to the high-speed shearing action during the preparation process, the anti-stripping agent, as a dispersed phase, is distributed in the asphalt, exhibiting a fluorescent effect. This reveals a scene of black asphalt phase and green anti-stripping agent intertwined and coexisting. It is clear that as the dosage of the anti-stripping agent increases, the fluorescence phenomenon gradually intensifies. The anti-stripping agent fully swells in the asphalt, its molecular chains are broken, and its distribution becomes more uniform. The physical properties of the anti-stripping agent are effectively combined with the asphalt, resulting in increased polarity and viscosity of the modified asphalt, and maximally improved performance.

[0073] (2) Fluorescence scanning was performed on HY70 and HY90 asphalt with different admixtures after aging, and their microscopic images were obtained as follows: Figure 4 As shown.

[0074] from Figure 4 It can be seen that after PAV aging, the number of fluorescent spots in the image is significantly reduced. This is mainly because aging causes the light components of the asphalt to transfer to the heavy components, reducing the light components. At the same time, some anti-stripping agents decompose, which leads to a weakening of the fluorescence effect in the image. Specifically, this is reflected in the weakening of the polarity of the modified asphalt, the reduction of viscosity, and the degradation of performance, indicating that long-term aging plays a dominant role in the destruction of the polymer.

[0075] 4.3 Mechanism To determine whether an amide reaction and hydrogen bond formation occurred between the anti-stripping agent and the base bitumen, liquid nuclear magnetic resonance (NMR) detection was performed using a 600MHz Bruker nuclear magnetic resonance spectrometer.

[0076] Test samples: HY70 base asphalt and asphalt modified with 0.4% anti-stripping agent, including RTFOT and PAV before and after aging. Samples were pretreated by heating and then dissolved in deuterated chloroform (CDCl3). Before testing, the samples were degassed to ensure no impurities interfered. The testing mode was two-dimensional HSQC (¹H–¹³C), acquiring hydrogen-carbon interactions in the molecule at room temperature. The test focused on C=O in the 160-180 ppm region and N–H or O–H signals in the 6-8 ppm range to assess the formation of amide-related functional groups and the presence of hydrogen bonding. Test results are as follows: Figure 5 As shown.

[0077] pass Figure 5 Together, they reveal the modification mechanism and chemical reaction characteristics of the anti-stripping agent of the present invention on the base asphalt, namely, that it generates amide bonds with the base asphalt during modification, thereby forming hydrogen bonds, improving the polarity and interfacial interaction strength of the modified asphalt, and enhancing the adhesion and anti-stripping ability of the asphalt-aggregate interface.

[0078] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite amine anti-stripping agent, characterized in that, It includes polyamide resin and sodium dodecylbenzene sulfonate; the mass fraction of the polyamide resin is 70%~85%, and the mass fraction of the sodium dodecylbenzene sulfonate is 15%~30%.

2. The composite amine anti-stripping agent according to claim 1, characterized in that, The polyamide resin has a mass fraction of 80%-85%, and the sodium dodecylbenzenesulfonate has a mass fraction of 15%-20%.

3. A method for preparing a composite amine anti-stripping agent, used to prepare the composite amine anti-stripping agent according to claim 2, characterized in that, Includes the following steps: S1. Weigh out the polyamide resin and sodium dodecylbenzene sulfonate according to their mass fractions; S2. Heat the polyamide resin to a fluid state; then add sodium dodecylbenzenesulfonate, and thoroughly shear and stir until evenly dispersed; finally, cool to obtain the final product.

4. The preparation method of the composite amine anti-stripping agent according to claim 3, characterized in that, In step S2, the heating temperature is 150±5℃, the shearing speed is 1000r / min-1200r / min, and the stirring time is 10min-15min.

5. The application of the composite amine anti-stripping agent as described in claim 1 in improving the adhesion performance between asphalt and aggregate.

6. The application of the composite amine anti-stripping agent as described in claim 1 in improving the high-temperature stability of asphalt.

7. The application of the composite amine anti-stripping agent as described in claim 1 in improving the low-temperature stability of asphalt.

8. The application according to claim 5, 6, or 7, characterized in that, When applied, the amount of the compound amine anti-stripping agent added is 0.3%-0.5% of the mass of the asphalt.

9. The application according to claim 8, characterized in that, In application, the compound amine anti-stripping agent is added to the asphalt, and modified by shearing and stirring to obtain modified asphalt; the modification temperature is 175±5℃, the shearing speed is 3000r / min-3200r / min, and the stirring time is 50min-55min.

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