A cold-mix asphalt mixture and its preparation method

Abstract

This invention relates to the field of asphalt mixtures and discloses a cold-mix asphalt mixture and its preparation method. The cold-mix asphalt mixture comprises: epoxy cold-mix asphalt, coarse aggregate, fine aggregate, mineral powder, and modified lignin fiber; the epoxy cold-mix asphalt comprises: base asphalt, diluent, modified epoxy resin, curing agent, SBR emulsion, and silane coupling agent; the modified epoxy resin is prepared using modified carboxyl-terminated low-polyester epoxy resin E44; the modified carboxyl-terminated low-polyester is prepared by replacing cyanuric chloride with pentaerythritol phosphate and then further substituting it with diethylene glycol to prepare a hydroxyl-terminated modified intermediate, which is then polyesterified by reacting glutaric acid with the hydroxyl-terminated modified intermediate; the modified lignin fiber is prepared by reacting lignin fiber, 2,2,6,6-tetramethylpiperidineamine, and formaldehyde through a Mannich reaction. The asphalt mixture prepared by this invention has good high and low temperature resistance, as well as excellent UV aging resistance and flame retardant effect.

Description

Technical Field

[0001] This invention belongs to the field of asphalt mixture technology, specifically relating to a cold-mix asphalt mixture and its preparation method. Background Technology

[0002] With the rapid development of transportation in daily life, the requirements for the quality and performance of road construction are increasing. Cold-mixed asphalt mixtures, as an environmentally friendly and energy-saving road material, have received widespread attention and application in recent years.

[0003] After cold-mix asphalt pavement is put into operation, in addition to being subjected to vehicle loads, it is also subjected to the combined effects of ultraviolet radiation and temperature, which has a certain impact on its service performance. Among the many influencing factors, ultraviolet radiation is one of the main factors causing long-term aging of asphalt pavement materials.

[0004] When asphalt pavement materials are exposed to sunlight, the chemical bonds in the binder with bond energies comparable to those in the ultraviolet band are prone to breakage under ultraviolet light. At the same time, the large number of fused ring compounds in asphalt readily absorb ultraviolet light and produce a photodegradation effect, inducing chemical reactions such as molecular isomerization, condensation, and dehydrogenation of asphalt molecules. This results in a significant decrease in the low-temperature crack resistance of asphalt pavement materials, ultimately leading to pavement diseases such as low-temperature cracking and spalling, which seriously affects the service performance and lifespan of asphalt pavements.

[0005] In addition, existing technologies can effectively improve or enhance the performance of large-void drainage asphalt pavements by adding epoxy asphalt. However, the low-temperature performance of traditional epoxy asphalt mixtures is relatively insufficient, and epoxy resin is a flammable material with a low limiting oxygen index, posing a flammability risk and threatening road safety. Summary of the Invention

[0006] To address the shortcomings mentioned in the background art, the present invention aims to provide a cold-mix asphalt mixture and its preparation method. The prepared cold-mix asphalt mixture has good high and low temperature resistance, as well as excellent UV aging resistance and flame retardant effect.

[0007] The objective of this invention can be achieved through the following technical solutions: A cold-mix asphalt mixture comprises the following components in parts by weight: 10-25 parts epoxy cold-mix asphalt, 60-80 parts coarse aggregate, 25-40 parts fine aggregate, 10-20 parts mineral powder, and 1-5 parts modified lignin fiber. The epoxy cold-mix asphalt comprises the following components by weight: 100 parts base asphalt, 10-30 parts diluent, 1.8-4 parts modified epoxy resin, 1.2-2.5 parts curing agent, 1.2-3 parts SBR emulsion, and 1.5-5 parts silane coupling agent. The modified epoxy resin is prepared by reacting modified carboxyl-terminated low-polyester with epoxy resin E44; the modified carboxyl-terminated low-polyester is prepared by replacing one chlorine atom in cyanuric chloride with pentaerythritol phosphate to prepare a modified intermediate, then using diethylene glycol to react with the remaining chlorine atom in the modified intermediate to prepare a hydroxyl-terminated modified intermediate, and then using glutaric acid to react with the hydroxyl-terminated modified intermediate to produce a polyesterification reaction. The modified lignin fiber is produced by the Mannich reaction of lignin fiber, 2,2,6,6-tetramethylpiperidineamine, and formaldehyde.

[0008] Preferably, the coarse aggregate is limestone with a particle size of 5-15 mm; the fine aggregate is limestone manufactured sand with a particle size of 0-5 mm; and the mineral powder is limestone powder with a particle size of 0-0.6 mm.

[0009] Preferably, the preparation method of the epoxy cold-mix asphalt includes the following steps: (1) Weigh each component according to the weight parts, heat and dehydrate the base asphalt to ensure that the asphalt is completely melted into a uniform state; (2) Add diluent to the molten base asphalt and stir thoroughly at 100~110℃ to form uniform diluted asphalt; (3) Add KH550 to the diluted asphalt, shear it evenly with a high-speed shearing machine, and then let it cool naturally to 80~90℃ to form a uniform asphalt liquid; (4) Add modified epoxy resin, SBR latex and curing agent to the asphalt liquid, and stir and mix evenly at 80~90℃ to prepare epoxy cold mix asphalt.

[0010] Preferably, the base asphalt is one of 70#, 90#, and 110#; the diluent is one of gasoline or diesel; the curing agent is polyamide 650 curing agent; and the silane coupling agent is KH550.

[0011] Preferably, the method for preparing the modified epoxy resin includes the following steps: I. Take cyanuric chloride and acetone in a reactor and stir and mix them at 0~5℃. Take pentaerythritol phosphate, acetone and potassium carbonate, stir and mix them and add them dropwise to the reactor. Stir and react for 5~7 hours. After the reaction is completed, filter, wash and concentrate to prepare the modified intermediate. II. Take the modified intermediate, diethylene glycol and m-xylene into a reactor, stir and react at 55~70℃ for 3~4h, then add 20% sodium hydroxide solution by mass, and continue stirring and reacting for 4~5h. After the reaction is completed, filter, wash and dry to prepare the hydroxyl-terminated modified intermediate. III. Take the hydroxyl-terminated modified intermediate, glutaric acid and m-xylene into a reactor, heat in an oil bath to 130~135℃, stir and react for 6~7h. After the reaction is completed, recover the solvent by atmospheric distillation, and then put it into a vacuum oven to dry, thus preparing the modified carboxyl-terminated low polyester. IV. Take the modified carboxyl-terminated low polyester, epoxy resin E44 and triphenylphosphine into a reactor, heat in an oil bath to 110~115℃, stir and react for 6~7h, and after the reaction is completed, put it into a vacuum oven to dry, and prepare the modified epoxy resin.

[0012] Preferably, in step I, the molar ratio of cyanuric chloride to pentaerythritol phosphate is 1:1 to 1.1; and in step II, the molar ratio of the modified intermediate to diethylene glycol is 1:2 to 2.5.

[0013] Preferably, in step III, the molar ratio of the terminal hydroxyl-modified intermediate to glutaric acid is 1:1.3~1.4.

[0014] Preferably, the method for preparing the modified lignin fiber includes the following steps: dispersing lignin fiber in deionized water, then adding 2,2,6,6-tetramethylpiperidineamine, adjusting the pH of the system to 10-12 using triethanolamine, stirring at 60-75°C for 15-30 min, then raising the temperature to 80-85°C, adding formaldehyde solution dropwise while stirring for 3-5 h, cooling to room temperature after the reaction is complete, washing and drying to obtain the modified lignin fiber.

[0015] Preferably, the length of the lignin fiber is <6 mm; the mass ratio of the lignin fiber, 2,2,6,6-tetramethylpiperidineamine and formaldehyde is 5:2:0.35~0.4.

[0016] The method for preparing cold-mix asphalt mixture as described above includes the following steps: S1. Weigh each component according to the weight parts, mix coarse aggregate, fine aggregate, mineral powder and modified lignin fiber for 1-2 minutes, then add externally added water to wet the aggregate, mix for 1-2 minutes, then add epoxy cold mix asphalt and mix for 1-2 minutes to obtain a uniformly mixed mixture. S2. Place the mixture into a mold, compact it 50 times on each side, cure it at room temperature for 24 hours, then cure it in a 60°C oven for 4 hours. Immediately after removing it, compact it 25 times on each side again, and finally cure it at 60°C for at least 20 hours. After cooling, demold it to obtain a cold-mixed asphalt mixture.

[0017] The beneficial effects of this invention are: This invention utilizes pentaerythritol phosphate to replace one chlorine atom in cyanuric chloride, preparing a modified intermediate with a triazine ring structure possessing good thermal stability and UV absorption, as well as a flame-retardant phosphate structure. Then, two diethylene glycol chains are used to undergo substitution reactions with the remaining two chlorine atoms of the modified intermediate to prepare a hydroxyl-terminated modified intermediate. Subsequently, glutaric acid is used to react with the hydroxyl-terminated modified intermediate in a polyesterification reaction to prepare a modified carboxyl-terminated low-polyester. Finally, the modified carboxyl-terminated low-polyester is reacted with epoxy resin E44 to prepare a modified epoxy resin. The resin introduces flexible segments into the three-dimensional network structure of epoxy resin E44 to achieve a toughening effect, thereby improving its low-temperature resistance. At the same time, the introduced triazine ring structure and flame-retardant phosphate ester structure can give the asphalt mixture good UV aging resistance and flame retardant properties. The modified epoxy resin is used as an effective component in epoxy cold mix asphalt, and SBR emulsion with excellent adhesion and durability is added. In addition, a silane coupling agent is added to act between organic polymers and inorganic fillers to strengthen the bond strength between them, thereby improving the overall performance of the asphalt mixture.

[0018] The coarse aggregate added to the cold-mix asphalt mixture prepared in this invention effectively improves the load-bearing capacity and durability of the mixture. The fine aggregate makes the internal structure of the mixture more compact, enhancing its resistance to water seepage and freeze-thaw cycles. Mineral powder improves the adhesion between asphalt and aggregate and also enhances the overall stability of the mixture by filling small voids. Furthermore, this invention utilizes the Mannich reaction of lignin fiber, 2,2,6,6-tetramethylpiperidineamine, and formaldehyde to prepare modified lignin fiber, thereby binding the hindered amine light stabilizer 2,2,6,6-tetramethylpiperidineamine to the surface of the lignin fiber through strong chemical bonds. The modified lignin fiber effectively inhibits its migration from the asphalt mixture matrix, significantly improving the UV resistance of the asphalt mixture. Furthermore, the introduction of 2,2,6,6-tetramethylpiperidinamine fills some of the voids in the lignin fibers, enhancing the adhesion between lignin fiber particles and forming a denser molecular structure, which is beneficial for improving high-temperature rutting resistance. In addition, the introduction of modified lignin fibers can effectively inhibit the flow of asphalt mixture, thereby reducing segregation losses. Moreover, modified lignin fibers have a reinforcing effect on the mineral skeleton, making the asphalt mixture structure more robust and effectively improving the water stability of the asphalt mixture structure. Detailed Implementation

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

[0020] Example 1: A method for preparing a modified epoxy resin includes the following steps: I. Take 9.2g of cyanuric chloride and 100mL of acetone in a reactor and stir and mix them at 0℃. Take 9.1g of pentaerythritol phosphate, 50mL of acetone and 6.9g of potassium carbonate and stir and mix them. Then add them dropwise to the reactor and stir and react for 6h. After the reaction is completed, filter, wash and concentrate to prepare the modified intermediate. II. Take 16.4g of the modified intermediate, 13.2g of diethylene glycol and 150mL of m-xylene in a reactor, stir and react at 65℃ for 4h, then add 25mL of 20% sodium hydroxide solution and continue stirring for 4h. After the reaction is completed, filter, wash and dry to prepare the hydroxyl-terminated modified intermediate. III. Take 23.3g of hydroxyl-terminated modified intermediate, 8.6g of glutaric acid and 150mL of m-xylene in a reactor, heat in an oil bath to 130℃, stir and react for 6h. After the reaction is completed, recover the solvent by atmospheric distillation, and then dry in a vacuum oven to prepare modified carboxyl-terminated low polyester. IV. Take 12g of modified carboxyl-terminated low polyester, 13.5g of epoxy resin E44 and 0.002g of triphenylphosphine into a reactor, heat in an oil bath to 110℃, stir and react for 7h. After the reaction is completed, put it into a vacuum oven to dry, and prepare the modified epoxy resin.

[0021] Example 2 A method for preparing modified lignin fiber includes the following steps: 10g of lignin fiber is dispersed in 40mL of deionized water, then 4g of 2,2,6,6-tetramethylpiperidineamine is added, the pH of the system is adjusted to 11 using triethanolamine, and the mixture is stirred at 70℃ for 20min. Then, the temperature is raised to 85℃, and 0.8g of formaldehyde solution is added dropwise while stirring for 4h. After the reaction is completed, the mixture is cooled to room temperature, washed, and dried to obtain modified lignin fiber.

[0022] Example 3 A cold-mix asphalt mixture comprising the following components by weight: 11 parts epoxy cold-mix asphalt, 61 parts limestone with coarse aggregate mass ratio of 1.6:1 and particle size of 5-10 mm and 10-15 mm, 25 parts limestone manufactured sand with fine aggregate particle size of 0-5 mm, 11 parts limestone powder with mineral powder particle size of 0-0.6 mm, and 1.5 parts modified lignin fiber prepared in Example 2.

[0023] The epoxy cold-mix asphalt comprises the following components by weight: 100 parts of base asphalt 70# asphalt, 12 parts of diluent 0# diesel oil, 1.8 parts of modified epoxy resin prepared in Example 1, 1.2 parts of polyamide 650 curing agent, 1.3 parts of SBR emulsion, and 1.6 parts of silane coupling agent KH550. The 70# asphalt has a penetration (25℃) of 64.3 / 0.1mm, a softening point of 48.5℃, and a ductility (5℃) of >100cm. The SBR emulsion has a viscosity of 1300~2000mPa·s and a solid content of 50±1%.

[0024] The above-mentioned method for preparing epoxy cold-mix asphalt includes the following steps: (1) Weigh each component by weight, heat and dehydrate the base asphalt until the temperature stabilizes at 125±5℃, and ensure that the asphalt is completely melted into a uniform state. (2) Add diluent to the molten base asphalt and stir thoroughly at 105°C to form a uniform diluted asphalt; (3) Add KH550 to the diluted asphalt, shear it evenly with a high-speed shearing machine, and then let it cool naturally to 85°C to form a uniform asphalt liquid; (4) Add modified epoxy resin, SBR latex and curing agent to the asphalt liquid, stir and mix evenly at 85°C to prepare epoxy cold mix asphalt.

[0025] A method for preparing cold-mix asphalt mixture includes the following steps: S1. Weigh each component according to the weight parts, mix coarse aggregate, fine aggregate, mineral powder and modified lignin fiber for 1 minute, then add externally added water to wet the aggregate, mix for 1 minute, then add epoxy cold mix asphalt and mix for 2 minutes to obtain a uniformly mixed mixture. S2. Place the mixture into a mold, compact it 50 times on each side, cure it at room temperature for 24 hours, then cure it in a 60°C oven for 4 hours. Immediately after removing it, compact it 25 times on each side again, and finally cure it at 60°C for at least 20 hours. After cooling, demold it to obtain a cold-mixed asphalt mixture.

[0026] Example 4 A cold-mix asphalt mixture comprising the following components by weight: 17 parts epoxy cold-mix asphalt, 69 parts limestone with a coarse aggregate mass ratio of 1.6:1 and a particle size of 5-10 mm and 10-15 mm, 30 parts limestone manufactured sand with a fine aggregate particle size of 0-5 mm, 15 parts limestone powder with a mineral powder particle size of 0-0.6 mm, and 3 parts modified lignin fiber prepared in Example 2.

[0027] The epoxy cold-mix asphalt comprises the following components by weight: 100 parts of base asphalt 70# asphalt, 17 parts of diluent 0# diesel oil, 2.8 parts of modified epoxy resin prepared in Example 1, 2 parts of polyamide 650 curing agent, 2.1 parts of SBR emulsion, and 3 parts of silane coupling agent KH550. The 70# asphalt has a penetration (25℃) of 64.3 / 0.1mm, a softening point of 48.5℃, and a ductility (5℃) of >100cm. The SBR emulsion has a viscosity of 1300~2000mPa·s and a solid content of 50±1%.

[0028] The preparation method of the above-mentioned epoxy cold-mix asphalt is the same as that in Example 3.

[0029] A method for preparing a cold-mix asphalt mixture is the same as in Example 3.

[0030] Example 5 A cold-mix asphalt mixture comprising the following components by weight: 23 parts epoxy cold-mix asphalt, 78 parts limestone with coarse aggregate mass ratio of 1.6:1 and particle size of 5-10 mm and 10-15 mm, 36 parts limestone manufactured sand with fine aggregate particle size of 0-5 mm, 18 parts limestone powder with mineral powder particle size of 0-0.6 mm, and 4.7 parts modified lignin fiber prepared in Example 2.

[0031] The epoxy cold-mix asphalt comprises the following components by weight: 100 parts of base asphalt 70# asphalt, 28 parts of diluent 0# diesel oil, 3.7 parts of modified epoxy resin prepared in Example 1, 2.4 parts of polyamide 650 curing agent, 2.9 parts of SBR emulsion, and 4.8 parts of silane coupling agent KH550. The 70# asphalt has a penetration (25℃) of 64.3 / 0.1mm, a softening point of 48.5℃, and a ductility (5℃) of >100cm. The SBR emulsion has a viscosity of 1300~2000mPa·s and a solid content of 50±1%.

[0032] The preparation method of the above-mentioned epoxy cold-mix asphalt is the same as that in Example 3.

[0033] A method for preparing a cold-mix asphalt mixture is the same as in Example 3.

[0034] Comparative Example 1: A method for preparing a modified epoxy resin includes the following steps: I. Take 9.2g of cyanuric chloride and 100mL of acetone in a reactor and stir and mix them at 0℃. Take 9.1g of pentaerythritol phosphate, 50mL of acetone and 6.9g of potassium carbonate and stir and mix them. Then add them dropwise to the reactor and stir and react for 6h. After the reaction is completed, filter, wash and concentrate to prepare the modified intermediate. II. Take 12g of modified intermediate, 13.5g of epoxy resin E44 and 0.002g of triphenylphosphine into a reactor, heat in an oil bath to 110℃, stir and react for 7h. After the reaction is completed, put it into a vacuum oven to dry, and prepare the modified epoxy resin.

[0035] Comparative Example 2: A cold-mix asphalt mixture comprising the following components by weight: 23 parts epoxy cold-mix asphalt, 78 parts limestone with coarse aggregate mass ratio of 1.6:1 and particle size of 5-10 mm and 10-15 mm, 36 parts limestone manufactured sand with fine aggregate particle size of 0-5 mm, 18 parts limestone powder with mineral powder particle size of 0-0.6 mm, and 4.7 parts modified lignin fiber prepared in Example 2.

[0036] The epoxy cold-mix asphalt comprises the following components by weight: 100 parts of base asphalt 70# asphalt, 28 parts of diluent 0# diesel oil, 3.7 parts of modified epoxy resin prepared in Comparative Example 1, 2.4 parts of polyamide 650 curing agent, 2.9 parts of SBR emulsion, and 4.8 parts of silane coupling agent KH550. The 70# asphalt has a penetration (25℃) of 64.3 / 0.1mm, a softening point of 48.5℃, and a ductility (5℃) of >100cm. The SBR emulsion has a viscosity of 1300~2000mPa·s and a solid content of 50±1%.

[0037] The preparation method of the above-mentioned epoxy cold-mix asphalt is the same as that in Example 3.

[0038] A method for preparing a cold-mix asphalt mixture is the same as in Example 3.

[0039] Comparative Example 3: A cold-mix asphalt mixture comprising the following components by weight: 23 parts epoxy cold-mix asphalt, 78 parts limestone with coarse aggregate mass ratio of 1.6:1 and particle size of 5-10 mm and 10-15 mm, 36 parts limestone manufactured sand with fine aggregate particle size of 0-5 mm, 18 parts limestone powder with mineral powder particle size of 0-0.6 mm, and 4.7 parts modified lignin fiber prepared in Example 2.

[0040] The epoxy cold-mix asphalt comprises the following components by weight: 100 parts of base asphalt 70# asphalt, 28 parts of diluent 0# diesel oil, 3.7 parts of epoxy resin E44, 2.4 parts of polyamide 650 curing agent, 2.9 parts of SBR emulsion, and 4.8 parts of silane coupling agent KH550. The 70# asphalt has a penetration (25℃) of 64.3 / 0.1mm, a softening point of 48.5℃, and a ductility (5℃) of >100cm. The SBR emulsion has a viscosity of 1300~2000mPa·s and a solid content of 50±1%.

[0041] The preparation method of the above-mentioned epoxy cold-mix asphalt is the same as that in Example 3.

[0042] A method for preparing a cold-mix asphalt mixture is the same as in Example 3.

[0043] Comparative Example 4: A cold-mix asphalt mixture comprising the following components by weight: 23 parts epoxy cold-mix asphalt, 78 parts limestone with coarse aggregate mass ratio of 1.6:1 and particle sizes of 5-10 mm and 10-15 mm, 36 parts manufactured limestone sand with fine aggregate particle size of 0-5 mm, 18 parts limestone powder with mineral powder particle size of 0-0.6 mm, 3.4 parts lignin fiber, and 1.3 parts 2,2,6,6-tetramethylpiperidinamine.

[0044] The epoxy cold-mix asphalt comprises the following components by weight: 100 parts of base asphalt 70# asphalt, 28 parts of diluent 0# diesel oil, 3.7 parts of modified epoxy resin prepared in Example 1, 2.4 parts of polyamide 650 curing agent, 2.9 parts of SBR emulsion, and 4.8 parts of silane coupling agent KH550. The 70# asphalt has a penetration (25℃) of 64.3 / 0.1mm, a softening point of 48.5℃, and a ductility (5℃) of >100cm. The SBR emulsion has a viscosity of 1300~2000mPa·s and a solid content of 50±1%.

[0045] The preparation method of the above-mentioned epoxy cold-mix asphalt is the same as that in Example 3.

[0046] A method for preparing a cold-mix asphalt mixture is the same as in Example 3.

[0047] Performance testing The performance of the cold-mix asphalt mixtures prepared in Examples 3-5 and Comparative Examples 2-4 was tested: (1) High temperature rutting test: 300mm×300mm×60mm rutting plate specimens were formed by wheel rolling method. After the specimens were kept in a 60℃ environmental chamber for 5 hours, they were rolled back and forth for 60 minutes using a standard test wheel (wheel pressure 0.7MPa) at a speed of 42 times / min. The rutting deformation at 45 minutes and 60 minutes was recorded. The high temperature deformation resistance of the mixture was evaluated by calculating the dynamic stability DS. The data results are shown in Table 1.

[0048] (2) Low-temperature bending beam test: prism beam specimens with dimensions of 250mm×30mm×35mm were cut from the cured rutted slab specimens. After the specimens were placed in a -20℃ environmental chamber for 3 hours, a three-point bending test was performed on a UTM universal testing machine at a loading rate of 50mm / min until the specimens broke. The maximum load and mid-span deflection at failure were recorded. The low-temperature crack resistance of the asphalt mixture was evaluated by the flexural tensile strength, maximum flexural tensile strain and flexural stiffness modulus. The data results are shown in Table 1.

[0049] (3) The oxygen index was used to evaluate the flame retardant performance of asphalt mixture. The oxygen index (LOI) of asphalt mixture refers to the minimum oxygen concentration required to sustain combustion in a mixture of oxygen and nitrogen. LOI = [O2] / ([O2] + [N2]) × 100%, where [O2] is the volumetric flow rate of oxygen in the mixed gas flow at the critical oxygen concentration; and [N2] is the volumetric flow rate of nitrogen in the mixed gas flow at the critical oxygen concentration. The data results are shown in Table 1.

[0050] (4) UV aging resistance test: The UV aging process was simulated using a UV aging chamber. A high-power high-pressure UV mercury lamp was used as the light source and a reflector was installed. The lamp was placed 30 cm away from the surface of the asphalt mixture sample and the irradiance was set to 2000 W / m. 2 The irradiation was carried out for 78.35 hours at a temperature controlled at 60℃. The flexural stiffness modulus at -20℃ after UV aging was tested, and the rate of change of flexural stiffness modulus before and after UV aging was calculated. The data results are shown in Table 1.

[0051] Table 1 Sample performance test results

[0052] As can be seen from the data results in Table 1, the asphalt mixtures prepared in Examples 3-5 of the present invention have good high and low temperature resistance, as well as excellent UV aging resistance and flame retardant effect. In Comparative Example 2, the modified epoxy resin added did not introduce flexible segments, and in Comparative Example 3, the modified epoxy resin E44 was not modified. The low-temperature resistance of the asphalt mixture in Comparative Examples 2-3 was found to be lower than that in Examples 3-5. This is because the introduction of flexible segments into the three-dimensional network structure of epoxy resin E44 can achieve a toughening effect, thereby improving its low-temperature resistance. Furthermore, the change rate of flexural stiffness modulus in Comparative Example 3 was significantly different from that in Examples 3-5, and the oxygen index was lower than that in Examples 3-5. This indicates that the introduction of the triazine ring structure and phosphate ester structure improved the UV aging resistance and flame retardant effect of the asphalt mixture to a certain extent. In Comparative Example 4, lignin fiber was directly mixed with 2,2,6,6-tetramethylpiperidinamine. The dynamic stability was lower than that in Examples 3-5, and the change rate of flexural stiffness modulus was significantly different from that in Examples 3-5. This indicates that the grafting reaction is beneficial to improving the high-temperature rutting resistance and UV aging resistance of the asphalt mixture.

[0053] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A cold-mix asphalt mixture, characterized in that, It includes the following components by weight: 10-25 parts epoxy cold-mix asphalt, 60-80 parts coarse aggregate, 25-40 parts fine aggregate, 10-20 parts mineral powder, and 1-5 parts modified lignin fiber; The epoxy cold-mix asphalt comprises the following components by weight: 100 parts base asphalt, 10-30 parts diluent, 1.8-4 parts modified epoxy resin, 1.2-2.5 parts curing agent, 1.2-3 parts SBR emulsion, and 1.5-5 parts silane coupling agent. The modified epoxy resin is prepared by reacting modified carboxyl-terminated low-polyester with epoxy resin E44; the modified carboxyl-terminated low-polyester is prepared by replacing one chlorine atom in cyanuric chloride with pentaerythritol phosphate to prepare a modified intermediate, then using diethylene glycol to react with the remaining chlorine atom in the modified intermediate to prepare a hydroxyl-terminated modified intermediate, and then using glutaric acid to react with the hydroxyl-terminated modified intermediate to produce a polyesterification reaction. The modified lignin fiber is produced by the Mannich reaction of lignin fiber, 2,2,6,6-tetramethylpiperidineamine, and formaldehyde.

2. The cold-mix asphalt mixture according to claim 1, characterized in that, The coarse aggregate is limestone with a particle size of 5-15 mm; the fine aggregate is limestone manufactured sand with a particle size of 0-5 mm; and the mineral powder is limestone powder with a particle size of 0-0.6 mm.

3. The cold-mix asphalt mixture according to claim 1, characterized in that, The preparation method of the epoxy cold-mix asphalt includes the following steps: (1) Weigh each component according to the weight parts, heat and dehydrate the base asphalt to ensure that the asphalt is completely melted into a uniform state; (2) Add diluent to the molten base asphalt and stir thoroughly at 100~110℃ to form uniform diluted asphalt; (3) Add KH550 to the diluted asphalt, shear it evenly with a high-speed shearing machine, and then let it cool naturally to 80~90℃ to form a uniform asphalt liquid; (4) Add modified epoxy resin, SBR latex and curing agent to the asphalt liquid, and stir and mix evenly at 80~90℃ to prepare epoxy cold mix asphalt.

4. The cold-mix asphalt mixture according to claim 1, characterized in that, The base asphalt is one of 70#, 90#, and 110#; the diluent is one of gasoline or diesel; the curing agent is polyamide 650 curing agent; and the silane coupling agent is KH550.

5. The cold-mix asphalt mixture according to claim 1, characterized in that, The preparation method of the modified epoxy resin includes the following steps: I. Take cyanuric chloride and acetone in a reactor and stir and mix them at 0~5℃. Take pentaerythritol phosphate, acetone and potassium carbonate, stir and mix them and add them dropwise to the reactor. Stir and react for 5~7 hours. After the reaction is completed, filter, wash and concentrate to prepare the modified intermediate. II. Take the modified intermediate, diethylene glycol and m-xylene into a reactor, stir and react at 55~70℃ for 3~4h, then add 20% sodium hydroxide solution by mass, and continue stirring and reacting for 4~5h. After the reaction is completed, filter, wash and dry to prepare the hydroxyl-terminated modified intermediate. III. Take the hydroxyl-terminated modified intermediate, glutaric acid and m-xylene into a reactor, heat in an oil bath to 130~135℃, stir and react for 6~7h. After the reaction is completed, recover the solvent by atmospheric distillation, and then put it into a vacuum oven to dry, thus preparing the modified carboxyl-terminated low polyester. IV. Take the modified carboxyl-terminated low polyester, epoxy resin E44 and triphenylphosphine into a reactor, heat in an oil bath to 110~115℃, stir and react for 6~7h, and after the reaction is completed, put it into a vacuum oven to dry, and prepare the modified epoxy resin.

6. The cold-mix asphalt mixture according to claim 5, characterized in that, In step I, the molar ratio of cyanuric chloride to pentaerythritol phosphate is 1:1 to 1.1; in step II, the molar ratio of the modified intermediate to diethylene glycol is 1:2 to 2.

5.

7. The cold-mix asphalt mixture according to claim 5, characterized in that, In step III, the molar ratio of the terminal hydroxyl-modified intermediate to glutaric acid is 1:1.3~1.

4.

8. The cold-mix asphalt mixture according to claim 1, characterized in that, The method for preparing the modified lignin fiber includes the following steps: dispersing lignin fiber in deionized water, then adding 2,2,6,6-tetramethylpiperidineamine, adjusting the pH of the system to 10-12 using triethanolamine, stirring at 60-75℃ for 15-30 min, then raising the temperature to 80-85℃, adding formaldehyde solution dropwise while stirring for 3-5 h, cooling to room temperature after the reaction is complete, washing and drying to obtain the modified lignin fiber.

9. The cold-mix asphalt mixture according to claim 8, characterized in that, The length of the lignin fiber is <6mm; the mass ratio of the lignin fiber, 2,2,6,6-tetramethylpiperidineamine, and formaldehyde is 5:2:0.35~0.

4.

10. The method for preparing cold-mix asphalt mixture according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Weigh each component according to the weight parts, mix coarse aggregate, fine aggregate, mineral powder and modified lignin fiber for 1-2 minutes, then add externally added water to wet the aggregate, mix for 1-2 minutes, then add epoxy cold mix asphalt and mix for 1-2 minutes to obtain a uniformly mixed mixture. S2. Place the mixture into a mold, compact it 50 times on each side, cure it at room temperature for 24 hours, then cure it in a 60°C oven for 4 hours. Immediately after removing it, compact it 25 times on each side again, and finally cure it at 60°C for at least 20 hours. After cooling, demold it to obtain a cold-mixed asphalt mixture.

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