Air triggered stress synergistic self-healing asphalt-based fiber rod and preparation method thereof

Abstract

The present application relates to the technical field of self-repairing materials, and discloses an air-triggered stress synergistic self-repairing asphalt-based fiber rod and a preparation method thereof, which comprises an asphalt-based outer layer and an air-triggered composite inner core, the asphalt-based outer layer is wrapped around the outer periphery of the air-triggered composite inner core, and a continuous and stable double-layer coaxial core-shell structure is formed. The double-layer coaxial core-shell structure of the air-triggered composite inner core and the asphalt-based outer layer is adopted, so that stress damage and air triggering are synergistically self-repaired, and the problems of low self-repairing efficiency and harsh triggering conditions of traditional asphalt-based materials are solved; the composite inner core is sealed and stored in the dark, remains stable and does not solidify when not in contact with air, and only starts solidification and repair when cracks occur and air penetrates, unnecessary pre-solidification waste is avoided, and the accuracy and reliability of self-repairing are improved; the asphalt-based stress-sensitive shell replaces the traditional polymer shell, is easy to break at low temperature, is stable at high temperature, and is completely homologous and compatible with asphalt.

Description

Technical Field

[0001] This invention relates to the field of self-healing materials technology, and in particular to air-triggered stress-synergistic self-healing asphalt-based fiber rods and their preparation methods. Background Technology

[0002] Asphalt pavement has become the mainstream pavement form for global transportation infrastructure due to its advantages such as high driving comfort, short construction period, and convenient maintenance. However, asphalt materials have inherent characteristics of low-temperature brittleness and high-temperature softening. During long-term service, it is highly susceptible to cracking due to factors such as temperature cycling, vehicle load, and rainwater erosion. In the low-temperature environment of winter, the brittleness of asphalt increases significantly, cracks initiate rapidly, and spread over a wide area. If not repaired in time, this can lead to water damage to the pavement structure and freeze-thaw damage, significantly shortening the pavement's service life and significantly increasing maintenance costs.

[0003] Currently, asphalt pavement self-healing technologies are mainly divided into two categories: microcapsule technology and hollow fiber technology. Microencapsulation technology: Urea resin is used as the outer shell to encapsulate asphalt rejuvenator. The content of the repair agent is extremely low (only 1%-5%), which can only repair micron-level microcracks. The outer shell is prone to brittleness at low temperatures and has poor compatibility with the asphalt matrix, which can easily cause pavement segregation and reduced strength. The cost is high (about 80 yuan / kg), making it difficult to apply on a large scale in engineering projects.

[0004] Hollow fiber technology: The outer shell is generally made of non-asphalt-based polymers / inorganic materials such as PVDF, polyamide (PA6 / PA66), PMMA, PET, and glass fiber tubes; the internal filling is a single substance or a simple physical mixture, including: single asphalt rejuvenator (rubber oil, aromatic oil, vacuum distillate oil), single epoxy resin (E-51 / E-44), single amine curing agent, simple mixture of epoxy and curing agent, and physical blend of epoxy and rejuvenator.

[0005] However, existing technologies have problems such as the outer shell being too hard to crack at low temperatures, demanding triggering conditions, lack of an air-triggered curing mechanism, and poor compatibility with asphalt. Summary of the Invention

[0006] The purpose of this invention is to provide an air-triggered stress-coordinated self-healing asphalt-based fiber rod and its preparation method in order to solve the above-mentioned problems.

[0007] The present invention achieves the above objectives through the following technical solutions: Air-triggered stress-synergistic self-healing asphalt-based fiber rods consist of an asphalt-based outer layer and an air-triggered composite inner core. The asphalt-based outer layer wraps around the air-triggered composite inner core, forming a continuous and stable double-layer coaxial core-shell structure. The asphalt-based outer layer comprises 70# road petroleum asphalt, 3wt% SBS modifier, and 0.3wt% silane coupling agent KH-550. The air-triggered composite inner core comprises, by percentage, 40%-50% epoxy resin, 20%-25% air-responsive amine curing agent, 10%-20% asphalt recycling agent, 5%-10% reinforcing filler, and 1%-2% coupling agent KH-550. The mass ratio of epoxy resin to air-responsive amine curing agent is strictly 2:1.

[0008] Furthermore: outer diameter 1-3mm, outer wall thickness 0.2-0.8mm, continuous, dense and without pores.

[0009] Furthermore: the 3wt% SBS modifier is linear or star-shaped; the 0.3wt% silane coupling agent KH-550 is γ-aminopropyltriethoxysilane.

[0010] Furthermore: the epoxy resin is E-51 or E-44; the air-responsive amine curing agent is ethylenediamine or diethylenetriamine; the asphalt recycling agent is aromatic rubber oil or furfural extract oil; and the reinforcing filler is nano-calcium carbonate or carbon fiber powder.

[0011] This invention also provides a method for preparing air-triggered stress-synergistic self-healing bitumen-based fiber rods, comprising the following steps: a. Stirring and developing to obtain an asphalt-based outer layer for later use; b. After stirring in a water bath according to the ratio, transfer to vacuum degassing to obtain an air-triggered composite core for later use; c. Using a twin-screw coaxial extruder, an asphalt-based outer layer and an air-triggered composite inner core are extruded in layers to obtain a continuous and stable double-layer coaxial core-shell fiber rod.

[0012] Furthermore, the specific steps of step a are as follows: a1. Add 70# base bitumen into the reactor and heat it to 150℃ to completely melt and dehydrate it; a2. Add 3wt% SBS modifier and allow it to swell and develop for 30 min under high-speed stirring conditions at 160℃ and 300r / min. a3. Cool down to 155℃, add 0.3wt% KH-550 coupling agent, and continue stirring for 15 minutes to disperse it evenly; a4. Discharge and set aside to obtain the asphalt-based outer layer.

[0013] Furthermore, the specific steps of step b are as follows: b1. Add epoxy resin, asphalt recycling agent and coupling agent KH-550 in sequence according to the ratio, and stir in a 70℃ water bath for 20 minutes until initially mixed and uniform. b2. Add reinforcing filler and ultrasonically disperse for 10 minutes to eliminate agglomeration; b3. Add air-responsive amine curing agent and stir quickly until homogeneous; b4. Immediately switch to nitrogen protection and vacuum degassing for 10 minutes to remove air bubbles and prevent pre-curing; b5. Store in a sealed, light-proof container to obtain an air-triggered composite core that does not harden when sealed but hardens only upon contact with air.

[0014] Furthermore, the specific parameters for step c are: Outer barrel temperature: 140℃-150℃; Inner core barrel temperature: 60℃-70℃; The ratio of the inner to outer layer feed rates is 1:3.5; Screw extrusion speed: 80 r / min.

[0015] Furthermore: the power for ultrasonic dispersion for 10 minutes is 200W to 300W; the vacuum degree for nitrogen-protected vacuum degassing for 10 minutes is -0.08MPa to -0.09MPa.

[0016] Furthermore, the die setting of the twin-screw coaxial extruder is a low-temperature air-cooled setting to avoid the core from being excited and solidified due to water cooling.

[0017] Compared with existing technologies, the beneficial effects are as follows: This invention employs a double-layer coaxial core-shell structure consisting of an air-triggered composite inner core and an asphalt-based outer layer, achieving synergistic self-healing of stress damage and air triggering, thus solving the problems of low self-healing efficiency and stringent triggering conditions of traditional asphalt-based materials. When the fiber rod cracks due to external force, air can quickly penetrate the crack and contact the composite core. At this time, the air-responsive amine curing agent in the core and the epoxy resin (the two are strictly mixed in a 2:1 mass ratio) rapidly undergo a curing reaction. At the same time, the asphalt recycling agent in the core can penetrate to the cracks in the outer layer of the asphalt base, achieving the dual effect of "crack healing + performance reinforcement", significantly improving service life and reducing later maintenance costs. In addition, the composite core is stored in a sealed, light-proof environment and remains stable and does not cure when not in contact with air. It only starts curing and repairing when cracks occur and air penetrates. The triggering method does not require additional energy or equipment, and the response is rapid and targeted, avoiding unnecessary pre-curing waste and improving the accuracy and reliability of self-repair. The asphalt-based stress-sensitive outer shell replaces the traditional polymer outer shell. It is easily broken at low temperatures, stable at high temperatures, and completely homologous to asphalt. It can repair large cracks of 0.5-5mm and can work stably at -20℃. It is stable in high-temperature mixing: it does not dissolve or break at 170℃, making it suitable for hot-mix road construction. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the air-triggered stress-coordinated self-healing asphalt-based fiber rod described in this invention; Figure 2 This is a flowchart of the preparation method of the air-triggered stress-coordinated self-healing asphalt-based fiber rod of the present invention; Figure 3 This is a flowchart of the specific steps in step a of the preparation method of the air-triggered stress-coordinated self-healing asphalt-based fiber rod described in this invention; Figure 4 This is a flowchart illustrating the specific steps of step b in the preparation method of the air-triggered stress-coordinated self-healing asphalt-based fiber rod described in this invention.

[0020] The annotations in the attached figures are explained as follows: 1. Asphalt-based outer layer; 2. Air-triggered composite inner core. Detailed Implementation

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] The present invention will be further described below with reference to the accompanying drawings: like Figure 1 As shown, the air-triggered stress-coordinated self-healing asphalt-based fiber rod includes an asphalt-based outer layer 1 and an air-triggered composite inner core 2. The asphalt-based outer layer 1 wraps around the outer periphery of the air-triggered composite inner core 2, forming a continuous and stable double-layer coaxial core-shell structure with an outer diameter of 1-3 mm and an outer wall thickness of 0.2-0.8 mm. It is continuous, dense, and pore-free.

[0024] Furthermore: the asphalt-based outer layer 1 comprises 70# road petroleum asphalt, 3wt% SBS modifier, and 0.3wt% silane coupling agent KH-550; the 3wt% SBS modifier is linear or star-shaped; the 0.3wt% silane coupling agent KH-550 is γ-aminopropyltriethoxysilane; Furthermore: the air-triggered composite core 2 comprises, by percentage, 40%-50% epoxy resin, 20%-25% air-responsive amine curing agent, 10%-20% asphalt rejuvenator, 5%-10% reinforcing filler, and 1%-2% coupling agent KH-550; the mass ratio of epoxy resin to air-responsive amine curing agent is strictly 2:1; the epoxy resin is E-51 or E-44; the air-responsive amine curing agent is ethylenediamine or diethylenetriamine; the asphalt rejuvenator is aromatic rubber oil or furfural extract oil; and the reinforcing filler is nano-calcium carbonate or carbon fiber powder. Application method: Add this fiber rod to the asphalt mixture at a mass fraction of 3%–8%, and form it on the asphalt pavement through conventional mixing, paving and compaction processes; when cracks occur in the pavement, the stress at the crack tip will break through the outer layer 1 of the asphalt matrix, exposing the air-triggered composite inner core 2 and exposing it to air. Subsequently, the air-triggered composite inner core 2 undergoes a curing reaction, filling the crack and bonding with the surrounding asphalt matrix, thus achieving in-situ self-repair of the crack.

[0025] Example 1 Air-triggered stress-coordinated self-healing bitumen-based fiber rods include a bitumen-based outer layer 1 and an air-triggered composite inner core 2. The bitumen-based outer layer 1 wraps around the outer periphery of the air-triggered composite inner core 2, forming a continuous and stable double-layer coaxial core-shell structure with an outer diameter of 1-3 mm and an outer wall thickness of 0.2-0.8 mm. The outer layer is continuous, dense, and pore-free.

[0026] Preferred: The asphalt-based outer layer 1 comprises 70# road petroleum asphalt, 3wt% SBS modifier, and 0.3wt% silane coupling agent KH-550; the 3wt% SBS modifier is linear, YH-791; the 0.3wt% silane coupling agent KH-550 is γ-aminopropyltriethoxysilane; the air-triggered composite inner core 2 comprises, by percentage, 46% epoxy resin, 23% air-responsive amine curing agent, 20% asphalt rejuvenator, 9% reinforcing filler, and 2% coupling agent KH-550; the mass ratio of epoxy resin to air-responsive amine curing agent is strictly 2:1; the epoxy resin is E-51; the air-responsive amine curing agent is ethylenediamine; the asphalt rejuvenator is aromatic rubber oil; and the reinforcing filler is nano-calcium carbonate.

[0027] Example 2 The difference between Example 2 and Example 1 is as follows: Preferably, the asphalt-based outer layer 1 comprises 70# road petroleum asphalt, 3wt% SBS modifier, and 0.3wt% silane coupling agent KH-550; the 3wt% SBS modifier is star-shaped; the 0.3wt% silane coupling agent KH-550 is γ-aminopropyltriethoxysilane; the air-triggered composite inner core 2 comprises, by percentage, 48% epoxy resin, 24% air-responsive amine curing agent, 17% asphalt rejuvenator, 9% reinforcing filler, and 2% coupling agent KH-550; the mass ratio of epoxy resin to air-responsive amine curing agent is strictly 2:1; the epoxy resin is E-51; the air-responsive amine curing agent is ethylenediamine; the asphalt rejuvenator is aromatic rubber oil; and the reinforcing filler is nano-calcium carbonate.

[0028] Example 3 The difference between Example 3 and Example 1 is as follows: Preferably, the asphalt-based outer layer 1 comprises 70# road petroleum asphalt, 3wt% SBS modifier, and 0.3wt% silane coupling agent KH-550; the 3wt% SBS modifier is star-shaped; the 0.3wt% silane coupling agent KH-550 is γ-aminopropyltriethoxysilane; the air-triggered composite inner core 2 comprises, by percentage, 50% epoxy resin, 25% air-responsive amine curing agent, 16% asphalt rejuvenator, 8% reinforcing filler, and 1% coupling agent KH-550; the mass ratio of epoxy resin to air-responsive amine curing agent is strictly 2:1; the epoxy resin is E-44; the air-responsive amine curing agent is diethylenetriamine; the asphalt rejuvenator is furfural extract oil; and the reinforcing filler is carbon fiber powder.

[0029] like Figure 2 As shown, the present invention also provides a method for preparing air-triggered stress-synergistic self-healing bitumen-based fiber rods, comprising the following steps: a. Stirring and developing to obtain asphalt-based outer layer 1 for later use; b. After stirring in a water bath according to the ratio, transfer to vacuum degassing to obtain air-triggered composite core 2 for later use; c. Using a twin-screw coaxial extruder, an asphalt-based outer layer 1 and an air-triggered composite inner core 2 are extruded in an inner-outer-outer-inner-layer manner to obtain a continuous and stable double-layer coaxial core-shell fiber rod with uniform outer diameter, consistent wall thickness, and no air bubbles in the inner core.

[0030] Furthermore: such as Figure 3 As shown, the specific steps of step a are as follows: a1. Add 70# base bitumen into the reactor and heat it to 150℃ to completely melt and dehydrate it; a2. Add 3wt% SBS modifier and allow it to swell and develop for 30 min under high-speed stirring conditions at 160℃ and 300r / min. a3. Cool down to 155℃, add 0.3wt% KH-550 coupling agent, and continue stirring for 15 minutes to disperse it evenly; a4. Discharge and set aside to obtain an asphalt-based outer layer 1 that is resistant to high temperatures, has controllable low-temperature brittleness, and is compatible with the asphalt matrix.

[0031] Furthermore: such as Figure 4 As shown, the specific steps of step b are as follows: b1. Add epoxy resin, asphalt recycling agent and coupling agent KH-550 in sequence according to the ratio, and stir in a 70℃ water bath for 20 minutes until initially mixed and uniform. b2. Add reinforcing filler and ultrasonically disperse for 10 minutes to eliminate agglomeration. The power of ultrasonic dispersion for 10 minutes is 200W to 300W. b3. Add air-responsive amine curing agent and stir quickly until homogeneous; b4. Immediately switch to nitrogen-protected vacuum degassing for 10 minutes. The vacuum level of nitrogen-protected vacuum degassing for 10 minutes is -0.08MPa to -0.09MPa, which is used to remove air bubbles and prevent pre-curing. b5. Store in a sealed, light-proof container to obtain an air-triggered composite core 2 that does not cure upon contact with air.

[0032] Furthermore, the specific parameters for step c are: Outer barrel temperature: 140℃-150℃; Inner core barrel temperature: 60℃-70℃; The ratio of the inner to outer layer feed rates is 1:3.5; Screw extrusion speed: 80 r / min; The die setting of the twin-screw coaxial extruder is low-temperature air-cooled to prevent the core from solidifying due to water cooling.

[0033] 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. An air-triggered stress-synergistic self-healing bitumen-based fiber rod, characterized in that: It includes an asphalt-based outer layer (1) and an air-triggered composite inner core (2). The asphalt-based outer layer (1) wraps around the outer periphery of the air-triggered composite inner core (2), forming a continuous and stable double-layer coaxial core-shell structure. The asphalt-based outer layer (1) comprises 70# road petroleum asphalt, 3wt% SBS modifier and 0.3wt% silane coupling agent KH-550; The air-triggered composite core (2) comprises, by percentage, 40%-50% epoxy resin, 20%-25% air-responsive amine curing agent, 10%-20% asphalt rejuvenator, 5%-10% reinforcing filler and 1%-2% coupling agent KH-550; the mass ratio of the epoxy resin to the air-responsive amine curing agent is strictly 2:

1.

2. The air-triggered stress-synergistic self-healing bitumen-based fiber rod according to claim 1, characterized in that: Outer diameter 1-3mm, outer wall thickness 0.2-0.8mm, continuous, dense and without pores.

3. The air-triggered stress-synergistic self-healing bitumen-based fiber rod according to claim 1, characterized in that: The 3wt% SBS modifier is linear or star-shaped; the 0.3wt% silane coupling agent KH-550 is γ-aminopropyltriethoxysilane.

4. The air-triggered stress-synergistic self-healing bitumen-based fiber rod according to claim 1, characterized in that: The epoxy resin is E-51 or E-44; the air-responsive amine curing agent is ethylenediamine or diethylenetriamine; the asphalt regenerator is aromatic rubber oil or furfural extract oil; and the reinforcing filler is nano-calcium carbonate or carbon fiber powder.

5. A method for preparing air-triggered stress-synergistic self-healing asphalt-based fiber rods, used to prepare the air-triggered stress-synergistic self-healing asphalt-based fiber rods according to any one of claims 1-4, characterized in that, The specific preparation method includes the following steps: a. Stirring and developing to obtain the asphalt-based outer layer (1) for later use; b. After stirring in a water bath according to the ratio, transfer to vacuum degassing to obtain the air-triggered composite core (2) for later use; c. Using a twin-screw coaxial extruder, the asphalt-based outer layer (1) and the air-triggered composite inner core (2) are extruded in layers to obtain a continuous and stable double-layer coaxial core-shell fiber rod.

6. The method for preparing air-triggered stress-synergistic self-healing bitumen-based fiber rods according to claim 5, characterized in that: The specific steps of step a are as follows: a1. Add 70# base bitumen into the reactor and heat it to 150℃ to completely melt and dehydrate it; a2. Add 3wt% SBS modifier and allow it to swell and develop for 30 min under high-speed stirring conditions at 160℃ and 300r / min. a3. Cool down to 155℃, add 0.3wt% KH-550 coupling agent, and continue stirring for 15 minutes to disperse it evenly; a4. Discharge and set aside to obtain the asphalt-based outer layer (1).

7. The preparation method of the air-triggered stress-synergistic self-healing bitumen-based fiber rod according to claim 5, characterized in that: The specific steps of step b are as follows: b1. Add the epoxy resin, the asphalt recycling agent and the coupling agent KH-550 in sequence according to the proportion, and stir in a 70°C water bath for 20 minutes until initially mixed and uniform. b2. Add the reinforcing filler and ultrasonically disperse for 10 minutes to eliminate agglomeration; b3. Add the air-responsive amine curing agent and stir quickly until homogeneous; b4. Immediately switch to nitrogen protection and vacuum degassing for 10 minutes to remove air bubbles and prevent pre-curing; b5. Store in a sealed, light-proof container to obtain the air-triggered composite core (2), which is sealed but does not cure and only cures when exposed to air.

8. The method for preparing air-triggered stress-synergistic self-healing bitumen-based fiber rods according to claim 5, characterized in that: The specific parameters for step c are as follows: Outer barrel temperature: 140℃-150℃; Inner core barrel temperature: 60℃-70℃; The ratio of the inner to outer layer feed rates is 1:3.5; Screw extrusion speed: 80 r / min.

9. The method for preparing air-triggered stress-synergistic self-healing bitumen-based fiber rods according to claim 7, characterized in that: The power of the ultrasonic dispersion for 10 minutes is 200W to 300W; the vacuum degree of the nitrogen-protected vacuum degassing for 10 minutes is -0.08MPa to -0.09MPa.

10. The method for preparing air-triggered stress-synergistic self-healing bitumen-based fiber rods according to claim 8, characterized in that: The die setting of the twin-screw coaxial extruder is a low-temperature air-cooled setting method to avoid the core from being stimulated and solidified due to water cooling.

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