Asphalt composite modifier and preparation method thereof, modified asphalt binder and preparation method and application thereof

Abstract

The invention belongs to the technical field of asphalt materials, and particularly relates to an asphalt composite modifier which comprises the following components in parts by weight: 60-90 parts of fly ash, 10-40 parts of a regenerated oil agent and 0-5 parts of an interface coupling accelerator, wherein the regenerated oil agent is adsorbed and fixed on the surface and in a pore structure of fly ash particles, and the modifier is powdery or granular. According to the invention, industrial solid waste fly ash is upgraded from traditional'filler replacement 'to a functional carrier, high-dosage and high-value utilization of bulk solid waste is realized, and the problems of land occupation and environmental pollution caused by fly ash stockpiling are effectively reduced; meanwhile, recycled or low-cost raw materials such as waste engine oil regeneration liquid and vegetable oil are selected as the regenerated oil agent, so that resource waste is avoided, and the idea of circular economy is met. The whole technical route does not need high-energy-consumption processing, and carbon emission and environmental load are greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of asphalt material technology, and particularly relates to asphalt composite modifiers and their preparation methods, modified asphalt binders and their preparation methods and applications. Background Technology

[0002] In road engineering, asphalt binder, as the core cementing material, is mixed with mineral aggregates to form asphalt mixtures, which are widely used in the paving of various types of roads. However, asphalt materials themselves have inherent defects such as high temperature sensitivity, susceptibility to rutting at high temperatures, susceptibility to cracking at low temperatures, insufficient adhesion to aggregates, and weak resistance to water damage. During long-term service, under the influence of environmental factors such as repeated vehicle loads, rain and snow erosion, and temperature fluctuations, the road surface is prone to rutting, cracks, and spalling, which seriously affect the service quality and lifespan of the road.

[0003] To improve the road performance of asphalt materials, the industry has developed various modification technologies: such as modifying the binder by adding polymers, using fiber-reinforced mixture structures, or adding mineral fillers such as limestone powder to optimize the performance of the asphalt mortar. Among these, mineral fillers mainly improve the viscosity of asphalt mortar and enhance interfacial adhesion through micro-filling. However, because these fillers lack chemical activity, they can only achieve physical-level performance adjustment, limiting their modification potential and making it difficult to fundamentally solve the problem of imbalanced high and low temperature performance of asphalt materials.

[0004] In recent years, fly ash, as a major industrial byproduct of coal-fired power plants, has been recognized for its micron-sized spherical morphology, certain specific surface area, and potential activity (mainly composed of...). Composed of oxides, fly ash has been attempted for application in the field of asphalt materials. In existing technologies, fly ash is mostly added in the form of partial replacement of limestone mineral powder. Although it can improve the rheological properties of asphalt mortar, enhance the high-temperature stability of the mixture, and strengthen the adhesion between asphalt and aggregates to a certain extent, this type of application is still limited to the traditional idea of ​​"physical filling substitution". It fails to fully activate the active components and interfacial interaction potential of fly ash, resulting in low functional utilization and inability to achieve high-value transformation.

[0005] In the field of reclaimed asphalt pavement (RAP) recycling, traditional technologies often restore the ductility and fluidity of aged asphalt by directly adding low-viscosity recycling agents (such as waste engine oil recycling fluid, vegetable oil, and bio-oil). However, this method has significant drawbacks: the one-time addition of recycling agents can lead to a substantial decrease in the high-temperature rutting resistance of the recycled asphalt, and the agents are prone to volatilization and loss during use, resulting in poor distribution uniformity and an inability to achieve long-term stable recycling effects. To address this issue, the industry has gradually explored slow-release recycling agent technologies, such as using porous inorganic carriers or microcapsules to encapsulate recycling components, enabling their gradual release to delay asphalt aging and impart self-healing capabilities to the material. However, these technologies generally suffer from complex processes, high production costs, and difficulties in large-scale production, making it difficult to meet the needs of practical engineering applications.

[0006] In summary, existing technologies face two major bottlenecks: First, the application of fly ash in asphalt materials remains at the level of "filler replacement," lacking a functional synergistic utilization pathway and failing to effectively combine its pore structure and active components with the needs of asphalt modification. Second, in asphalt recycling technology, traditional methods of using recycling agents cannot simultaneously address low-temperature performance recovery and high-temperature stability maintenance, while novel slow-release technologies are limited by cost and process constraints, hindering industrialization. Therefore, there is an urgent need to develop a technical solution that integrates high-value utilization of solid waste, asphalt modification, and recycling functions. This solution should achieve large-scale disposal of fly ash while addressing issues such as comprehensive performance optimization of asphalt materials and stable RAP recycling effects, while also meeting engineering requirements for low-carbon environmental protection, cost control, and construction compatibility. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned technical problems by providing asphalt composite modifiers and their preparation methods, modified asphalt binders and their preparation methods, and their applications.

[0008] A composite asphalt modifier includes fly ash, a recycled oil agent, and an interfacial coupling accelerator, wherein, by weight, fly ash comprises 60-90 parts, recycled oil agent comprises 10-40 parts, and interfacial coupling accelerator comprises 0-5 parts. The regenerated oil agent is adsorbed and fixed on the surface and pore structure of fly ash particles, and the modifier is in powder or granular form.

[0009] A modified asphalt binder includes a base asphalt and 10% to 40% of the composite modifier by weight of the base asphalt.

[0010] A method for preparing a composite modifier includes the following steps: The fly ash is dried. Under heating and stirring conditions, a regenerating oil agent is added to fly ash, so that the regenerating oil agent is adsorbed by the fly ash and forms immobilized composite particles. The surface of the immobilized composite particles is modified by adding an interfacial coupling accelerator and then cooling to obtain the composite modifier, or the composite modifier is obtained by granulation after cooling.

[0011] A method for preparing modified asphalt binder involves heating and stirring base asphalt, and gradually adding a composite modifier at a weight of 10% to 40% of the base asphalt at that temperature, dispersing it evenly, and then cooling it to obtain the modified asphalt binder.

[0012] Application of a modified asphalt binder in the preparation of hot-mix asphalt mixtures or recycled asphalt mixtures from old asphalt pavement.

[0013] The beneficial effects of this invention are: In this invention, the composite modifier incorporates 60%–90% fly ash, upgrading industrial solid waste fly ash from a traditional "filler substitute" to a functional carrier. This achieves high-volume, high-value utilization of bulk solid waste, effectively reducing the land occupation and environmental pollution caused by fly ash stockpiling. Simultaneously, the regenerated oil agent uses recycled or low-cost raw materials such as waste engine oil regeneration fluid and vegetable oil, avoiding resource waste and aligning with the circular economy concept. The entire technical route eliminates the need for energy-intensive processing, significantly reducing carbon emissions and environmental impact, thus meeting the current industrial demand for low-carbon and environmentally friendly solutions.

[0014] Through a multi-mechanism approach of "immobilized slow-release of regenerated oil agent + synergistic effect of fly ash activity + regulation by interfacial coupling accelerator," this invention overcomes the bottleneck of existing technologies where "low-temperature performance recovery and high-temperature stability are mutually exclusive": ① The porous structure of fly ash enables the slow release of the regenerated oil agent, avoiding the decrease in high-temperature strength of asphalt caused by one-time addition, while gradually restoring the viscoelastic properties of aged asphalt and taking into account low-temperature crack resistance; ② The fly ash contains The synergistic effect of active oxides and interfacial coupling accelerators significantly enhances the adhesion between asphalt and aggregates and improves resistance to water damage; ③ The fine particle filling effect of fly ash improves the stiffness of asphalt mastic, and combined with the "softening" effect of recycled oil, achieves "soft-hard balance", reduces the temperature sensitivity of asphalt materials, and greatly improves the comprehensive road performance of high-temperature rutting resistance and low-temperature cracking resistance; In addition, the local release of recycled oil at microcracks can wet the crack surface, giving the material self-healing potential, effectively delaying the development of pavement diseases and extending the service life of roads.

[0015] The composite modifier of this invention can simultaneously achieve two core functions without additional supporting equipment: firstly, it can directly modify the base asphalt to prepare high-performance modified asphalt binders; secondly, it can be applied to the recycling of reclaimed asphalt pavement (RAP), restoring the ductility of aged binders while maintaining the high-temperature stability of recycled mixtures, thus solving the cumbersome problem of separate processing for "modification" and "recycling" in traditional technologies. It is suitable for various application scenarios such as hot-mix asphalt mixtures and RAP recycled mixtures, significantly broadening the engineering applicability of the technology and reducing the overall cost of road construction and maintenance.

[0016] The composite modifier is available in powder or granular form, facilitating storage, transportation, and precise metering. Its preparation process is simple, requiring no complex equipment, and it is highly compatible with existing asphalt mixing and RAP recycling processes, requiring no modification to existing production equipment and can be directly integrated into engineering construction workflows. Its low operational threshold and strong adaptability effectively reduce the difficulty and cost of technology promotion, demonstrating significant industrialization feasibility.

[0017] In terms of raw materials, fly ash and recycled oil agents are both low-cost or recyclable raw materials, significantly replacing expensive mineral powder, polymer modifiers, and new asphalt, thereby significantly reducing the cost of asphalt material preparation and road engineering. From an environmental perspective, it reduces solid waste landfill pollution, resource waste, and carbon emissions, alleviating ecological pressure. From an engineering perspective, by improving the pavement's resistance to damage and its self-healing potential, it reduces the frequency and cost of subsequent maintenance, lowering the total life-cycle cost. This achieves a harmonious balance of economic, environmental, and social benefits. Attached Figure Description

[0018] Figure 1 A schematic diagram of the preparation process of fly ash-based composite modifier; Figure 2 This is a schematic diagram illustrating the microscopic self-healing effect of asphalt materials incorporating the modifier of this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0021] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0022] Example 1: Preparation of fly ash-based composite modifier and its modification of matrix asphalt: (1) Preparation of modifiers (e.g.) Figure 1 (As shown): Select fly ash from a coal-fired power plant (in this embodiment, high-calcium fly ash is used, for example, CaO mass fraction of 5% to 20%; loss on ignition LOI ≤ 8%; median particle size D50 of 5 to 40 μm, which can be adjusted appropriately according to the source). Dry the fly ash to remove adsorbed water (e.g., dry to a moisture content < 1%).

[0023] The fly ash is then heated to 120–150°C and stirred continuously. At this temperature, a regenerated oil agent (such as waste engine oil regeneration fluid, vegetable oil, bio-oil, or lubricating oil fraction; the viscosity of the regenerated oil agent at 60°C is preferably 50–500 mPa·s) is gradually added. The regenerated oil agent is adsorbed by the fly ash and pre-immobilized. Stirring is maintained for 10–40 minutes to ensure uniform distribution of the immobilized composite particles.

[0024] After cooling the system to 80–110°C, add the interfacial coupling accelerator (such as an amine anti-stripping agent or a silane coupling agent). The preferred amount of accelerator is 0.5%–3.0% of the fly ash mass. Continue stirring for 5–20 minutes to complete the surface modification. Allow to cool naturally to room temperature to obtain the powdered composite modifier. For easier metering and addition, further granulation can be performed, with a particle size preferably of 1–5 mm. During granulation, 2%–8% (mass fraction) of wax or asphalt can be added as a forming aid.

[0025] It should be noted that the loading of the regenerated oil agent (based on the total mass of the modifier) ​​can be determined by the 105℃ isothermal mass difference method, and is usually controlled within the range of 10% to 30% to balance the low-temperature recovery ability and high-temperature stability.

[0026] (2) Preparation of modified asphalt: 70# road petroleum asphalt was selected as the base asphalt and heated to 160-180℃ while stirring. The above-mentioned composite modifier was added in batches according to 10%-40% of the mass of the base asphalt. After each batch was added, stirring or shearing was continued to ensure that the modifier was evenly dispersed and formed a stable system. If necessary, shearing for 5-30 minutes could be performed to promote the diffusion and homogenization of the recycled oil agent in the binder. Finally, degassing and cooling were performed to obtain the modified asphalt binder. The modified binder usually exhibits a darker color and a slightly improved consistency.

[0027] (3) Performance testing and criteria (e.g.) Figure 2 As shown, Figure 2 This demonstrates the process by which fly ash particles adsorb recycled oil to form a "microcapsule" structure, and release the recycled oil to wet the crack surface and promote healing after crack formation: Compared with unmodified base asphalt, modified asphalt typically exhibits the following characteristics under standard test conditions: Improved high-temperature rheological properties: softening point shows an upward trend; DSR complex modulus |G*| increases and phase angle δ decreases, indicating improved high-temperature stability and rutting resistance; Low-temperature performance retention: Ductility remained at a reasonable level at 5°C, with no significant degradation observed; Enhanced adhesion and resistance to water damage: Both adhesion and water damage tests showed an improvement trend; Temperature sensitivity is reduced: the range of fluctuation of rheological parameters with temperature changes at different temperatures is reduced.

[0028] These phenomena are consistent with the slow-release and interface synergy mechanism proposed in this invention: the porous structure of fly ash forms "microencapsulated slow release" of the regenerated oil agent, avoiding the high-temperature performance degradation caused by one-time refueling; the surface active oxides of fly ash interact with the polar groups of asphalt, improving adhesion performance; the filling effect of fine fly ash particles enhances the stiffness of the mortar, achieving "soft-hard balance" together with the regenerated oil agent.

[0029] Example 2: Application of fly ash-based composite modifier in the recycling of reclaimed asphalt pavement (RAP): (1) Materials and Modification Treatment: Severely aged RAP materials after many years of service were selected. The RAP can be heat-treated first to reduce viscosity and promote mixing, or the aged binder can be recovered by extraction for comparison. The composite modifier of this invention is added at 10% to 25% of the mass of the recycled binder (the specific dosage is determined according to the rubber content of the RAP and the target performance). The mixture is stirred / sheared in the range of 150 to 170°C to fully disperse the modifier and complete the regeneration and activation, thus obtaining the recycled modified asphalt binder.

[0030] At the mixture level, hot-mix recycled mixtures with RAP content of 30% to 50% can be prepared, and new aggregates and new binders can be added appropriately to meet the design gradation and asphalt-aggregate ratio; composite modifiers can be added with the binder or dry-mixed with RAP first and then added to the binder, both methods can be implemented.

[0031] (2) Performance Comparison and Applicability: Compared with unmodified aged binders, recycled modified asphalt typically exhibits the following characteristics: restored penetration, softening point reduced to a more reasonable range, significantly restored ductility, reduced viscosity at 135℃, and improved workability; it also maintains a high modulus under high-temperature conditions and does not experience a decrease in strength due to recycled oil agents. The recycled mixtures prepared in this way show improved trends in Marshall stability, splitting tensile strength, water immersion residual stability (TSR), rutting performance, and fatigue performance.

[0032] The above effects are consistent with the mechanism of Example 1: the slow-release effect of the regenerated oil agent can restore the low-temperature ductility; the interfacial activation and rheological regulation of fly ash can maintain high-temperature stability and improve adhesion, thereby achieving a comprehensive balance between high and low temperature performance and water damage resistance in the regeneration system.

[0033] As demonstrated by the above embodiments, the pre-adsorbed immobilized fly ash composite modifier provided by this invention can be used as a modifier for asphalt binders and can also be applied to RAP recycling systems. While improving high-temperature stability, enhancing interfacial adhesion and water damage resistance, it maintains good low-temperature ductility, thus achieving a synergistic effect of integrated modification and recycling. Compared with the traditional method of "fly ash merely replacing filler," this invention achieves the functional utilization of fly ash at the binder level through carrier-based slow release and interfacial activation, possessing good engineering applicability and industrialization prospects.

[0034] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. An asphalt composite modifier, characterized in that, It includes fly ash, regenerated oil agent and interfacial coupling accelerator, with fly ash 60-90 parts, regenerated oil agent 10-40 parts and interfacial coupling accelerator 0-5 parts by weight. The regenerated oil agent is adsorbed and fixed on the surface and pore structure of fly ash particles, and the modifier is in powder or granular form.

2. A modified asphalt binder, characterized in that: It includes base asphalt and 10% to 40% by weight of the composite modifier described in claim 1.

3. A method for preparing the composite modifier according to claim 1, characterized in that, Includes the following steps: The fly ash is dried. Under heating and stirring conditions, a regenerating oil agent is added to fly ash, so that the regenerating oil agent is adsorbed by the fly ash and forms immobilized composite particles. The surface of the immobilized composite particles is modified by adding an interfacial coupling accelerator and then cooling to obtain the composite modifier, or the composite modifier is obtained by granulation after cooling.

4. A method for preparing the modified asphalt binder according to claim 2, characterized in that: The base asphalt is heated and stirred. At this temperature, a composite modifier is gradually added at 10% to 40% of the weight of the base asphalt. After it is evenly dispersed, it is cooled to obtain the modified asphalt binder.

5. The application of the modified asphalt binder according to claim 2 in the preparation of hot-mix asphalt mixtures or recycled asphalt mixtures from old asphalt pavement.

6. The composite modifier according to claim 1, characterized in that: The fly ash meets one or more of the following performance indicators: CaO mass fraction of 5% to 20%; loss on ignition (LOI) ≤ 8%; median particle size D50 of 5 to 40 μm; specific surface area of ​​0.2 to 10 m² / g.

7. The asphalt composite modifier according to claim 6, characterized in that, The regenerated oil agent is selected from waste engine oil regeneration fluid, vegetable oil, bio-oil, or petroleum lubricating oil fraction; the viscosity of the regenerated oil agent at 60°C is 50–500. It has an acid value ≤5mgKOH / g and is compatible with asphalt.

8. The asphalt composite modifier according to claim 7, characterized in that, The loading of the regenerated oil agent is 10% to 30% based on the total mass of the modifier.

9. The asphalt composite modifier according to claim 8, characterized in that, The interface coupling accelerator is selected from amine anti-stripping agents, silane coupling agents, or surfactants; the amount of the interface coupling accelerator is 0.5% to 3.0% of the fly ash mass; if the modifier is granular, its particle size is 1 to 5 mm.

10. The method for preparing modified asphalt binder according to claim 4, characterized in that: After adding the composite modifier, shearing and stirring are performed to promote the diffusion and uniform distribution of the regenerated oil agent and fly ash components.

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