Preparation method of self-healing anti-oxidation regenerated asphalt

Abstract

The invention discloses a preparation method of self-healing and anti-oxidation recycled asphalt, and belongs to the technical field of recycled asphalt preparation. The preparation method of the self-healing and anti-oxidation regenerated asphalt comprises the following steps: firstly, calcining a biomass material in an oxygen-free gas flow; then performing modification treatment by using an activating agent to obtain modified biochar; and finally, preparing the regenerated asphalt mixture by taking the modified charcoal, an aromatic hydrocarbon regenerant, SBS and the like as regenerated asphalt modifiers. The method is simple in process, low in cost, environmentally friendly, sustainable and high in designability. On one hand, the modified charcoal and the aromatic hydrocarbon regenerant effectively improve the mechanical strength of the regenerated asphalt; on the other hand, the modified charcoal enhances the adsorption effect on the aromatic hydrocarbon regenerant, and improves the anti-aging performance and the self-healing capability of the regenerated asphalt. Finally, under the condition of relatively low use amount of the aromatic hydrocarbon regenerant, the regenerant and the modified charcoal effectively improve the self-healing and self-repairing capabilities of the regenerated asphalt, and the secondary aging is relieved.

Description

Technical Field

[0001] The present invention relates to the technical field of recycled asphalt preparation, and particularly relates to a method for preparing self-healing and antioxidant recycled asphalt. Background Art

[0002] Recycled asphalt has been widely used in fields such as road engineering, waterproof engineering, and building foundation engineering due to its environmental protection and sustainability. However, due to asphalt aging, the performance of recycled asphalt pavements often fails to meet the standards required for asphalt roads. Adding an appropriate amount of aromatic hydrocarbon regenerant to aged asphalt is a common strategy to reduce the agglomeration of polar groups in aged asphalt and is also the key to effectively restoring the mechanical properties of recycled asphalt. However, a relatively high dosage of aromatic hydrocarbon regenerant is required to significantly improve the mechanical properties of recycled asphalt; and aromatic hydrocarbon regenerants are volatile, and under the combined influence of environmental factors and traffic, recycled asphalt is easily re-aged, ultimately seriously affecting the service life of asphalt pavements. In view of this, preventing the volatilization of aromatic hydrocarbon regenerants in recycled asphalt and improving the self-repair and self-healing ability of the asphalt system have become hot topics of concern in the academic and industrial circles, and are of great significance for achieving stable performance and long life of recycled asphalt pavements, as well as sustainable utilization of energy.

[0003] In view of the above problems, this invention document proposes a method for preparing self-healing and antioxidant recycled asphalt. Summary of the Invention

[0004] The purpose of the present invention is to solve the disadvantages of poor mechanical properties of recycled asphalt and the volatility of aromatic hydrocarbon regenerants, and to propose a method for preparing self-healing and antioxidant recycled asphalt.

[0005] In order to achieve the above purpose, the present invention adopts the following technical scheme:

[0006] A method for preparing self-healing and antioxidant recycled asphalt, by weight, is prepared by mixing 3 - 6 parts of modified biochar, 100 parts of aged asphalt, 2 - 6 parts of aromatic hydrocarbon regenerant, 1 - 4 parts of SBS modifier, 0.1 - 0.9 part of stabilizer, and 15 - 25 parts of petroleum asphalt; the modified biochar is rich in oxygen-containing functional groups, and these functional groups have a strong adsorption effect on aromatic molecules.

[0007] Preferably, the aged asphalt accounts for 70 - 85% of the total recycled asphalt mixture.

[0008] A method for preparing self-healing and antioxidant recycled asphalt includes the following steps:

[0009] S1. Dry the biomass material and sinter it in an oxygen-free gas stream, and collect the biochar after cooling, denoted as A;

[0010] S2. Mix the alkaline, acidic or neutral activator with A in a certain mass ratio, add an appropriate amount of pure water and stir, then dry and grind to obtain B;

[0011] S3. Sinter the mixture B in an oxygen-free gas stream to obtain modified biochar rich in functional groups, denoted as C;

[0012] S4. Heat 100 parts of the collected aged asphalt in an electric furnace to 140 - 170 °C, weigh 15 - 25 parts of petroleum asphalt and 3 - 6 parts of modified biochar C, and slowly and evenly add them to the melted aged asphalt. Keep the temperature of the asphalt mixture at 140 - 170 °C in a constant-temperature electric furnace, and then use a high-speed disperser to stir at 200 - 700 r / min for 10 - 30 min;

[0013] Subsequently, add 2 - 6 parts of aromatic hydrocarbon regenerant and 1 - 4 parts of SBS modifier, and use a high-speed shearing machine to shear at a speed of 2000 - 6000 r / min for 30 - 60 min. During this high-speed shearing, the asphalt temperature needs to be raised to 170 - 190 °C;

[0014] Finally, add 0.1 - 0.9 parts of stabilizer while maintaining the temperature at 170 - 190 °C, and use a high-speed disperser to stir at 200 - 700 r / min for 30 - 60 min to obtain self-healing and antioxidant regenerated asphalt.

[0015] Preferably, in S1, the biomass material is selected from at least one of materials rich in cellulose and lignin such as waste wood, straw, and bamboo.

[0016] Preferably, in S1, the carbonization temperature range is 300 - 700 °C.

[0017] Preferably, in S2, the selected activator includes at least one of alkaline activators, acidic activators, and neutral activators;

[0018] Among them, the alkaline activator includes but is not limited to at least one of KOH, NaOH, or K2CO3;

[0019] The acidic activator includes but is not limited to at least one of HNO3, H3PO4, or H2SO4;

[0020] The neutral activator includes but is not limited to at least one of ZnCl2, FeCl3, CaCl2, KMnO4, or H2O2.

[0021] Preferably, in S3, the oxidation temperature range is 400 - 1000 °C.

[0022] Preferably, in S4, the modified biochar component is crushed to 200 - 1000 mesh.

[0023] Preferably, in S4, the aromatic hydrocarbon regenerant is one or more of petroleum-based, bio-based, or engineering waste oil.

[0024] Preferably, in S4, the stabilizer is sulfur powder.

[0025] Preferably, in S4, the SBS modifier includes one or more of linear SBS modifier or SBS star-shaped modifier.

[0026] Compared with the prior art, the present invention provides a method for preparing self-healing and antioxidant recycled asphalt, having the following beneficial effects:

[0027] The method for preparing self-healing and antioxidant recycled asphalt includes the following steps: First, calcine the biomass material in an oxygen-free gas stream; then modify it with an activator to obtain modified biochar; finally, use the modified biochar, aromatic hydrocarbon regenerant, and SBS, etc. as recycled asphalt modifiers to prepare a recycled asphalt mixture. This method has simple technology, easily available raw materials, low cost, environmental protection and sustainability, and strong designability. Among them, the modified biochar is obtained by calcining the biomass material in an oxygen-free gas stream and then modifying it with an activator. On the one hand, the modified biochar, aromatic hydrocarbon regenerant, and SBS effectively improve the mechanical strength of the aged asphalt (recycled asphalt); on the other hand, the biochar rich in functional groups has a strong adsorption effect on the aromatic hydrocarbon regenerant, improving the anti-aging performance and self-healing ability of the recycled asphalt. This study combines the performance advantages of each component to complement each other, solving the problem of easy volatilization of the aromatic hydrocarbon regenerant in asphalt. Finally, at a lower dosage of the aromatic hydrocarbon regenerant, the modified biochar and regenerant effectively alleviate the secondary aging of the recycled asphalt by virtue of their own functional advantages. At the same time, they improve the mechanical strength of the recycled asphalt and extend the service life of the recycled asphalt pavement. Description of the Drawings

[0028] Figure 1 It is a research technical roadmap of a self-healing and antioxidant recycled asphalt proposed in Example 1 of the present invention;

[0029] Figure 2 It is the stress-strain curve graph of three asphalt models in Example 1 of the present invention;

[0030] Figure 3 It is the "gap" cavity diagram of the aged asphalt model in Example 1 of the present invention;

[0031] Figure 4 It is the "elliptical" cavity diagram in the biochar-modified recycled asphalt model in Example 1 of the present invention;

[0032] Figure 5 It is the three-dimensional model diagram of the modified biochar adsorbing the aromatic hydrocarbon regenerant in Example 1 of the present invention;

[0033] Figure 6 This is a three-dimensional model diagram of the modified biochar adsorption aromatic hydrocarbon regenerant in other directions in Embodiment 1 of the present invention. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0035] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0036] Embodiment 1:

[0037] In this embodiment, waste poplar sawdust is selected as the raw material to prepare modified biochar.

[0038] A formula for self-healing and antioxidant regenerated asphalt includes: modified biochar, aromatic hydrocarbon regenerant, SBS modifier, stabilizer sulfur powder, virgin petroleum asphalt, and aged asphalt.

[0039] It is prepared according to the following steps:

[0040] S1. Select waste poplar sawdust, and in a nitrogen atmosphere, heat it to 450 °C at a heating rate of 5 °C / min in a tube furnace, hold for 30 min, take it out after natural cooling, and record the product as A1;

[0041] S2. Select KOH solution as the modifier, mix the KOH solution with A1 at a mass ratio of 1:1, add an appropriate amount of pure water and stir, then dry and grind, and record the product as B1;

[0042] S3. Sinter B1 in a nitrogen atmosphere, heat it to 800 °C at a heating rate of 4 °C / min, hold for 30 min, cool and collect it in a nitrogen stream, and record the product as C1;

[0043] S4. Crush the modified biochar C1 to 300 mesh;

[0044] S5. Heat 100 portions of aged asphalt collected in an electric furnace to 170 °C, weigh 15 portions of petroleum asphalt and 4 portions of modified biochar C1, and slowly and evenly add them to the heated aged asphalt. Keep the temperature of the asphalt mixture at 170 °C with a constant-temperature electric furnace, and then use a high-speed disperser to stir at 400 r / min for 30 min;

[0045] Subsequently, add 3 portions of aromatic hydrocarbon regenerant and 2 portions of SBS modifier, and use a high-speed shearer to shear at a speed of 6000 r / min for 60 min. During this high-speed shearing period, the asphalt temperature needs to be raised to 190 °C;

[0046] Finally, at 190 °C, add 0.9 portion of stabilizer sulfur powder, and use a high-speed disperser to stir at 700 r / min for 60 min to obtain self-healing and antioxidant regenerated asphalt.

[0047] The mechanical properties of the regenerated modified asphalt prepared in this example are shown in Table 1; for comparison, we also tested the mechanical properties of virgin asphalt, aged asphalt, and aromatic hydrocarbon regenerated asphalt only (regenerated asphalt) as a control group to characterize the degree of performance recovery of the regenerated asphalt by the modified biochar. Among them, the bulk modulus characterizes the compressive resistance of the material, the shear modulus characterizes the ability of the material to resist shear strain, and the Young's modulus characterizes the ability of the solid material to resist deformation; among them, compared with the aged asphalt, the regenerated modified asphalt obtained in Example 1 has different degrees of recovery in each mechanical property;

[0048] Compared with the regenerated asphalt, the regenerated modified asphalt obtained in Example 1 is stronger in mechanical properties;

[0049] Compared with the virgin asphalt, the bulk modulus and Young's modulus of the asphalt obtained in Example 1 are larger, indicating that its compressive resistance and deformation resistance are enhanced.

[0050] In addition, for mechanism explanation, we used the method of molecular dynamics simulation to establish a virgin asphalt model, an aged asphalt model, and a regenerated modified asphalt model (Example 1 model) respectively. After simulation and optimization, the analysis of mechanical properties and intermolecular interactions was carried out, and its technical route is as Figure 1 shown.

[0051] First, stretch the three types of asphalt along the longitudinal axis direction at 298 K, set each strain to 0.5%, and stretch for 140 steps. The stress-strain curves are as Figure 2 shown, showing the same numerical trend as the experimental values. At the same time, in order to observe the crack propagation during the stretching process of the molecular dynamics simulation, we compared the fracture progress. After applying an external load, the asphalt model elongates along the longitudinal axis direction. As Figure 3As shown, in the aged asphalt model, continuous loading causes nano-voids to expand and merge with adjacent nano-voids, forming "crack" cavities, which then fracture; while in the biochar-modified recycled asphalt model (as Figure 4 shown), continuous loading causes the cracks to exhibit "elliptical" cavities. From a macroscopic perspective, aged asphalt exhibits characteristics such as low ductility and high stiffness during the tensile process, while the modified biochar and aromatic hydrocarbon regenerants, due to their small molecular weights, are effectively dispersed within the asphalt matrix, penetrate the gaps between asphalt molecules, depolymerize some aggregated asphaltene molecules, and thus enhance the fluidity of asphalt molecules, making the mechanical properties of asphalt change from "brittle" to "tough".

[0052] Figure 5 and Figure 6 are the molecular models of the modified biochar and aromatic hydrocarbon regenerants constructed in the simulation box of , and the three-dimensional model diagrams in different directions obtained after optimization and simulation. It can be seen that the small-molecule regenerants are all adsorbed around the modified biochar. Among them, the adsorption of the aromatic hydrocarbon regenerant by the large number of benzene ring aggregations and carboxyl groups in the modified biochar molecules is relatively strong.

[0053] Example 2:

[0054] In this example, modified biochar is prepared using waste dry leaves as raw materials.

[0055] A formulation for self-healing and antioxidant recycled asphalt includes: modified biochar, aromatic hydrocarbon regenerant, SBS modifier, stabilizing sulfur powder, virgin petroleum asphalt, and aged asphalt.

[0056] It is prepared according to the following steps:

[0057] 1) Select waste leaves and dry them. Under an argon atmosphere, heat them in a tubular furnace at a heating rate of 4 °C / min to 500 °C, hold for 30 min, and take them out after natural cooling, denoted as A2;

[0058] 2) Select H2O2 as the modifier, mix it with A2 in a mass ratio of 1:1, add an appropriate amount of pure water and dry it for later use. The product is denoted as B2;

[0059] 3) Sinter B2 in an argon atmosphere, heat it at a heating rate of 5 °C / min to 900 °C, hold for 30 min, cool it in an argon stream and collect it. The product is denoted as C2;

[0060] 4) Crush the modified biochar C2 to 800 mesh;

[0061] 5) Heat 100 portions of collected aged asphalt in an electric furnace to 150 °C, weigh 20 portions of petroleum asphalt and 5 portions of modified biochar C2, and slowly and evenly add them to the heated aged asphalt. Keep the temperature of the asphalt mixture at 150 °C with a constant-temperature electric furnace, and then use a high-speed disperser to stir at 400 r / min for 30 min;

[0062] Subsequently, add 4 portions of aromatic hydrocarbon regenerant and 3 portions of SBS modifier, and use a high-speed shearing machine to shear at a speed of 6000 r / min for 60 min. During this high-speed shearing period, the asphalt temperature needs to be raised to 190 °C;

[0063] Finally, at 190 °C, add 0.9 portion of stabilizer sulfur powder, and use a high-speed disperser to stir at 600 r / min for 60 min to obtain self-healing and antioxidant recycled asphalt.

[0064] The mechanical properties of the recycled modified asphalt prepared in this example are shown in Table 1.

[0065] Among them, compared with the aged asphalt, the recycled modified asphalt obtained in Example 2 has improved mechanical properties.

[0066] Table 1 Performance parameters of asphalt

[0067]

[0068] To sum up, this study takes molecular structure design as the strategy and first proposes to use modified biochar materials in the field of recycled asphalt technology. As the pyrolysis product of biomass waste, modified biochar is modified by an activator to introduce a large number of oxygen-containing functional groups. These functional groups have a strong adsorption effect on aromatic hydrocarbon regenerants, replacing the limited improvement ability of single-component aromatic hydrocarbon regenerants on the performance of recycled asphalt. Finally, relying on its excellent self-healing and self-repair functions, it effectively alleviates the secondary aging of recycled asphalt, and combines the performance advantages of each component to make up for each other, solves the problem of easy volatilization of aromatic hydrocarbon regenerants in asphalt, effectively improves the antioxidant and self-healing abilities of the recycled asphalt system, and then realizes the performance stability of recycled asphalt pavements and extends the service life.

[0069] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A self-healing, antioxidant regenerated asphalt, characterized in that, The recycled asphalt composition includes: modified biochar, aromatic hydrocarbon regenerant, SBS modifier, stabilizer, virgin petroleum asphalt, and aged asphalt.

2. The self-healing and antioxidant regenerated asphalt according to claim 1, wherein, The recycled asphalt raw materials, by weight, include 3 - 6 parts of modified biochar, 100 parts of aged asphalt, 2 - 6 parts of aromatic hydrocarbon regenerant, 1 - 4 parts of SBS modifier, 0.1 - 0.9 parts of stabilizer, and 15 - 25 parts of petroleum asphalt.

3. The self-healing and antioxidant regenerated asphalt according to claim 2, wherein The aged asphalt accounts for 70 - 85% of the total recycled asphalt mixture.

4. The preparation method of a self-healing and antioxidant regenerated asphalt according to claim 3, characterized in that, It includes the following steps: S1. Dry the biomass material and sinter it in an oxygen - free stream. After cooling, collect the obtained biochar, denoted as A. S2. Mix an alkaline, acidic, or neutral activator with A in a certain mass ratio, add an appropriate amount of pure water and stir. Then dry and grind it, denoted as B. S3. Sinter the mixture B in an oxygen - free stream to obtain modified biochar rich in functional groups, denoted as C. S4. Heat 100 parts of the collected aged asphalt in an electric furnace to 140 - 170 °C. Weigh 15 - 25 parts of petroleum asphalt and 3 - 6 parts of modified biochar C, and slowly and evenly add them to the melted aged asphalt. Keep the temperature of the asphalt mixture at 140 - 170 °C in a constant - temperature electric furnace, and then use a high - speed disperser to stir at 200 - 700 r / min for 10 - 30 min. Subsequently, add 2 - 6 parts of aromatic hydrocarbon regenerant and 1 - 4 parts of SBS modifier, and use a high - speed shearing machine to shear at a speed of 2000 - 6000 r / min for 30 - 60 min. During this high - speed shearing, the asphalt temperature needs to be raised to 170 - 190 °C. Finally, add 0.1 - 0.9 parts of stabilizer while maintaining the temperature at 170 - 190 °C, and use a high - speed disperser to stir at 200 - 700 r / min for 30 - 60 min to obtain self - healing and antioxidant recycled asphalt.

5. The preparation method of a self-healing and antioxidant regenerated asphalt according to claim 4, characterized in that, The biomass material is selected from at least one of materials rich in cellulose and lignin such as waste wood, straw, and bamboo.

6. The preparation method of a self-healing and antioxidant regenerated asphalt according to claim 4, characterized in that, In S1, the carbonization temperature range is 300 - 700 °C.

7. The preparation method of a self-healing and antioxidant regenerated asphalt according to claim 4, characterized in that, In S2, the selected activator includes at least one of alkaline activators, acidic activators, and neutral activators. Among them, the alkaline activator includes but is not limited to at least one of KOH, NaOH, or K2CO3. The acidic activator includes but is not limited to at least one of HNO3, H3PO4, or H2SO4. The neutral activator includes but is not limited to at least one of ZnCl2, FeCl3, CaCl2, KMnO4, or H2O2.

8. The preparation method of a self-healing and antioxidant regenerated asphalt according to claim 4, characterized in that, In S3, the oxidation temperature range is 400 - 1000 °C.

9. The preparation method of a self-healing and antioxidant regenerated asphalt according to claim 4, characterized in that, In S4, the modified biochar component is crushed to 200 - 1000 mesh. The aromatic hydrocarbon regenerant comes from one or more of petroleum - based, bio - based, or engineering waste oils.

10. The preparation method of a self-healing and antioxidant regenerated asphalt according to claim 4, characterized in that, In S4, the stabilizer is sulfur powder. The SBS modifier includes one or more of linear SBS modifiers or SBS star - shaped modifiers.

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