A method for preparing and constructing asphalt pavement pothole repair blocks

Abstract

This application proposes a method for preparing and constructing pothole repair blocks for asphalt pavements. Preparation method: Dry-mixed low-melting-point polyether-type TPU granules with preheated aggregates (oil-rich RAP material and steel slag); then wet-mixed with heated base asphalt and recycling agent, followed by the addition of mineral powder to obtain a mixture; finally, low-pressure static pressing is used to form repair blocks with an open-pore structure. Construction method: Clean the pothole and apply emulsified asphalt; calculate the required number of repair blocks based on the pothole volume; microwave activation: place the repair blocks in a heating box, and place the heating box in a microwave oven to heat the repair blocks until they become a molten mixture; casting: quickly pour the molten mixture from the heating box into the cleaned pothole and level it with a scraper. This application, through the synergistic effect of dry TPU and microwave activation with steel slag, can simultaneously achieve high solid waste utilization, high toughness, and rapid and convenient construction for repairing potholes in asphalt pavements.

Description

[Technical Field] This application relates to the field of road repair technology, and in particular to a method for preparing and constructing pothole repair blocks for asphalt pavement. [Background Technology] With my country's highway network entering its maintenance phase on a large scale, rapid and durable repair of potholes in asphalt pavements has become an urgent need for the industry. The timeliness and quality of asphalt pavement pothole repair are core challenges in maintenance work. On the other hand, road maintenance and the steel industry generate large amounts of solid waste, such as recycled asphalt pavement material (RAP) and steel slag. The dumping of this solid waste not only occupies land but may also cause environmental pollution. Therefore, developing a repair material that can absorb solid waste on a large scale while possessing excellent road performance, especially high toughness and durability, is of great significance for promoting the green and sustainable development of the highway industry.

[0001] Currently, the most similar prior art and its defects are as follows: (1) Traditional wet-process TPU (thermoplastic polyurethane) modified bitumen preparation for repair materials This technical solution typically includes the following steps: First, the TPU modifier and the base asphalt are mixed at high temperatures. Under high-temperature conditions (typically 165-185°C), homogeneous TPU-modified asphalt is prepared by long-term blending (typically 30-60 minutes) using a high-speed shearing device (shear rate often exceeding 4000 rpm). This pre-prepared modified asphalt is then used as a binder and mixed with aggregates, mineral powder, etc., in a mixing pot at a specific ratio under heating to obtain a polymer-modified asphalt mixture for road paving.

[0002] This technology has the following drawbacks: wet TPU modification requires specialized high-temperature, high-speed shearing equipment. Furthermore, modified asphalt suffers from storage stability issues, leading to complex production processes, high energy consumption, and increased costs, making it difficult to promote its application in ordinary mixing plants. In addition, due to the prolonged high-temperature shearing of TPU during the wet process, some TPU molecular chains may break and degrade, preventing the full retention of its inherent high elasticity in the final mixture. Particularly when this technology is applied to the product form of "precast repair test blocks," the modified asphalt continues to age during storage, and the heat transfer from the surface to the interior is slow and uneven when using traditional external heat sources on-site. This causes the surface polymer-modified asphalt to undergo secondary or even tertiary thermal oxidation aging, while the internal modified asphalt fails to fully melt, resulting in severe degradation of the final activated mixture's performance and failure to achieve the expected repair effect.

[0003] (2) General dry-process asphalt mixture preparation technology with added modifiers This technology typically involves directly adding solid materials such as fibers, rubber granules, and plastic granules into the mixing pot during the initial or middle stages of aggregate and asphalt mixing. The main mechanisms of action of fiber additives (such as polyester fibers and lignin fibers) are reinforcement, oil absorption, and stabilization. They form a three-dimensional network in the mixture, physically inhibiting asphalt flow, thereby reducing segregation and improving stability. However, fibers themselves do not melt into a binder phase during heating, thus failing to significantly improve the flexibility and toughness of the mixture. The addition of rubber / plastic granules is usually to consume specific solid waste or utilize their elasticity. However, their poor compatibility with asphalt and weak interfacial bonding often lead to reduced mixture strength and difficulty in achieving uniform dispersion.

[0004] The technology has the following drawbacks: since conventional dry additives (such as fibers) mainly play a reinforcing and stabilizing role rather than melt bonding, they cannot form a continuous network structure after heating like TPU, thus having limited improvement on the toughness and low-temperature crack resistance of the mixture.

[0005] (3) Factory-prefabricated asphalt mixture repair blocks This approach typically involves using hot-mix asphalt mixtures (which may be conventional SBS-modified or high-modulus asphalt) The asphalt mixture is pressed into slabs of a certain size in the factory. During on-site construction, external heat sources such as open flames, hot air, or heat-conducting oil plates are needed to heat the bottom of the pit and the repair block for a long time, from the surface to the inside, so that they are softened and then compacted and bonded.

[0006] The technology has the following drawbacks: the heating of traditional precast repair blocks relies on heat conduction from the outside to the inside from an external heat source, resulting in extremely low heating efficiency and a long heating time (usually more than 40 minutes). It is also very easy to cause severe aging of the surface asphalt while the inside remains unsoftened, forming a "burnt outside, raw inside" phenomenon, which seriously affects the repair quality. At the same time, the existing precast block technology has not been designed with materials for microwave heating, and its aggregates usually do not have good microwave absorption characteristics, making it impossible to use an efficient and uniform microwave heating method for activation.

[0007] (4) High proportion of RAP material recycling technology This technology typically involves adding large amounts of recycled asphalt pavement (RAP) to road repair or paving materials to achieve large-scale utilization of maintenance solid waste resources. To ensure the initial asphalt-aggregate ratio of the mixture, in actual engineering projects, it is often preferable to select RAP with a higher content of old asphalt.

[0008] This technology has the following drawbacks: because the old asphalt in the RAP material is exposed to the natural environment and traffic loads for a long time, it has undergone severe oxidation and aging, and the lightweight components have volatilized, resulting in a significant decrease in its activity. In precast block products, if there is a lack of effective instantaneous activation methods, the old asphalt in the RAP material only serves as "black aggregate" and cannot regain its bonding properties, resulting in insufficient durability of the repaired structure.

[0009] Therefore, how to solve the problems of uneven on-site heating of precast blocks, polymer performance degradation and low solid waste utilization rate in the existing technology is one of the technical problems that urgently need to be solved in this field. [Summary of the Invention] The purpose of this application is to provide a method for preparing and constructing asphalt pavement pothole repair blocks. By using dry TPU, steel slag microwave absorbing aggregate and oil-rich RAP material in synergy, combined with a specific pore structure formed by low-pressure prefabrication, the method aims to solve the problems of uneven on-site heating of precast blocks, polymer performance degradation and low solid waste utilization rate in the prior art.

[0010] This application provides a method for preparing asphalt pavement pothole repair blocks, including the following steps: S1. Raw material preparation and pretreatment: Prepare aggregates, base asphalt, recycling agent, mineral powder and low melting point polyether TPU particles; preheat the aggregates to 120-160℃, and dry the polyether TPU particles.

[0011] S2. Dry mixing: Put the preheated aggregate and the dried polyether TPU granules into a forced intermittent mixing pot and dry mix for 50-70 seconds; S3. Wet mixing: Add base asphalt and recycling agent heated to 150-165℃ to the forced intermittent mixing pot and wet mix for 50-70 seconds, then add mineral powder and continue mixing for 80-100 seconds to obtain the mixture; S4. Repair block molding: Quickly transfer the mixed material into the mold, statically press it for 20-35 seconds under a low pressure of 0.5-3MPa, and after demolding and cooling, a repair block with an open pore structure is obtained.

[0012] Furthermore, the aggregate is composed of oil-rich RAP material and steel slag; the recycling agent is 3%-8% of the mass of old asphalt contained in the oil-rich RAP material.

[0013] Furthermore, the polyether-type TPU particles have a particle size of 1-4 mm, a melt index of 15-25 g / 10 min, and a melting point of 120-150 °C.

[0014] Further, in step S1, the drying process involves drying the polyether-type TPU particles at 60℃-80℃ for 2-4 hours to reduce their moisture content to below 0.1%.

[0015] Furthermore, in step S4, the pressure is preferably 1.0 MPa-2.0 MPa.

[0016] Furthermore, in step S4, the mold is a rectangular mold or a cylindrical mold.

[0017] Furthermore, in the repair block prepared in step S4, the mass percentage of the polyether-type TPU particles is 1%-5%, and the mass percentage of the aggregate is ≥90%.

[0018] This application also provides a method for constructing asphalt pavement pothole repair blocks, using the repair blocks prepared above, including the following steps: On-site preparation: Clean the pit and calculate the number of repair blocks needed based on the volume of the pit; Microwave activation: Place the repair block in a heating box and then place the heating box in a microwave oven to heat for 3-8 minutes; utilize the wave absorption properties of steel slag to heat the inside of the repair block until the polyether-type TPU particles melt, thus obtaining a molten mixture; Casting and molding: Quickly pour the molten mixture in the heating box into the cleaned pit and level it with a scraper.

[0019] Furthermore, a thin layer of emulsified asphalt is applied as a tack coat inside the cleaned pit.

[0020] Furthermore, the heating box is a microwave-resistant engineering plastic heating box.

[0021] Compared with the prior art, this application has the following beneficial effects: This application addresses the problems of uneven on-site heating of precast blocks, polymer performance degradation, and low solid waste utilization in existing technologies by using dry TPU, steel slag microwave absorbing aggregate, and oil-rich RAP material in synergy, combined with a specific pore structure formed by low-pressure prefabrication.

[0022] This application abandons the traditional "wet" modification process and creatively adopts a "dry" method to directly premix solid TPU particles with aggregates. Firstly, it completely eliminates the complex, expensive, and energy-intensive high-temperature, high-speed shear modification equipment and processes, enabling the production line to be implemented in any conventional asphalt mixing plant, significantly lowering the industrialization threshold and production costs. Simultaneously, because the TPU particles avoid prolonged high-temperature shear stress during pre-modification, their polymer chain structure is fully preserved. This allows their inherent high elasticity, high toughness, and other superior properties to be "stored" almost without loss in the precast repair blocks and completely released upon final use, solving the technical pain point of polymer pre-degradation in wet processes.

[0023] This application utilizes a microwave oven to activate the repair block. The steel slag within the repair block not only acts as a hard aggregate, but its contained metal oxides (such as Fe3O4) also serve as highly efficient microwave sensitive agents, capable of instantly and uniformly converting microwave energy into heat energy, achieving "volume heating" of the repair material from the inside out. This heating method allows the TPU particles dispersed in the mixture to melt synchronously and rapidly, thus forming a homogeneous and continuous three-dimensional polymer network structure with the asphalt in a very short time (approximately 3-8 minutes) at the construction site. This achieves a perfect transformation of the mixture from a "rigid precast block" to a "high-toughness castable," with final performance far exceeding that of traditional hot-mix asphalt. This enables the repair of potholes in asphalt pavements. [Attached Image Description] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A flowchart illustrating the manufacturing process of asphalt pavement pothole repair blocks provided in this application embodiment; Figure 2 This is a flowchart illustrating the construction method for asphalt pavement pothole repair blocks provided in an embodiment of this application.

Detailed Implementation Methods

[0025] It should be understood that the described embodiments are merely some, not all, of the embodiments in this specification. All other embodiments obtained by those skilled in the art based on the embodiments in this specification without inventive effort are within the scope of protection of this specification.

[0026] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this specification. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] The technical solutions protected by the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0028] Please see Figure 1 The present application provides a method for preparing an asphalt pavement pothole repair block, comprising the following steps: See Figure 1As shown, this application discloses a method for preparing asphalt pavement pothole repair blocks, including the following steps: S1. Raw material preparation and pretreatment: Prepare aggregates, base asphalt, recycling agent, mineral powder, and low-melting-point polyether TPU granules. Preheat the aggregates to 120-160℃, and dry the polyether TPU granules. The aggregates consist of oil-rich RAP material and steel slag, and the recycling agent is 3%-8% of the mass of the old asphalt contained in the oil-rich RAP material. Preheating the aggregates to 120-160℃ aims to remove moisture, activate the surface activity of the aggregates, and prevent excessive aging of the old asphalt in the oil-rich RAP material. The drying process involves drying the polyether TPU granules at 60℃-80℃ for 2-4 hours until their moisture content is below 0.1%.

[0029] As one implementation method, the aggregate preheating process is as follows: oil-rich RAP material and steel slag are separately placed into a drying drum and heated to 130°C±10°C. The polyether-type TPU particles have a particle size of 1-4 mm, a melt index of 15-25 g / 10 min, and a melting point of 120-150°C to ensure rapid melting and flow during subsequent microwave heating. The particle size of the polyether-type TPU particles is preferably 2-3 mm. When the oil-rich RAP material has a particle size of less than 4.75 mm, the steel slag particle size is 4.7-13.5 mm.

[0030] S2. Dry mixing: The preheated aggregate and the dried polyether-type TPU granules are put into a forced intermittent mixing pot and dry-mixed for 50-70 seconds. Preferably, it is dry-mixed for 60 seconds.

[0031] Specifically, the preheated aggregate and the metered solid TPU particles are put into a forced intermittent mixing pot and dry-mixed for 60 seconds at a temperature of 120-150°C. The purpose of this step is to make the TPU particles evenly dispersed and physically adhered to the surface of the aggregate.

[0032] S3. Wet mixing: Add base asphalt heated to 150-165°C and a recycling agent to a forced-batch mixing pot and wet mix for 50-70 seconds, preferably 60 seconds. Then add mineral powder and continue mixing for 80-100 seconds, preferably 90 seconds, to obtain a mixture. At this time, the hot asphalt will come into contact with the surface of the TPU particles, causing surface swelling and partial melting, forming a preliminary, heterogeneous "asphalt-TPU" composite binder, thereby encapsulating the aggregate. As one embodiment, add base asphalt heated to 150-165°C and a recycling agent to a forced-batch mixing pot, wet mix for 60 seconds at 145°C ± 5°C, then add mineral powder and continue mixing for 90 seconds to obtain a mixture.

[0033] S4. Repair Block Molding: The mixed material is quickly transferred to a mold and statically pressed for 20-35 seconds under a low pressure of 0.5-3 MPa. After demolding and cooling, a repair block with an open pore structure is obtained. The mass percentage of polyether-type TPU particles in the obtained repair block is 1%-5%, and the mass percentage of aggregate is ≥90%.

[0034] Specifically, at room temperature, the mixed material is quickly transferred into a mold and compacted for 20-35 seconds using a static pressing method under a low pressure of 0.5-3 MPa. The preferred pressure is 1.0 MPa-2.0 MPa.

[0035] Preferably, the patch is compacted at a low pressure of 1.0 MPa for 30 seconds, and then demolded and cooled. This low pressure is intended to give the patch sufficient strength for handling and storage, while maintaining a relatively loose open structure to facilitate microwave energy penetration and uniform internal heating.

[0036] The mold is a rectangular mold or a cylindrical mold, such as a rectangle of 100mm×100mm×50mm or a cylinder of 100mm in diameter and 50mm in height.

[0037] S5. Packaging and Warehousing: Cool the molded repair blocks to below 40°C at room temperature, then seal them in plastic bags and store them in a dry warehouse. Repair blocks are recommended for use within 12 months.

[0038] The regenerator is a liquid asphalt regenerator, preferably refined waste edible oil as a bio-based regenerator. Combined with a high proportion of RAP material and steel slag, a fully cyclical regeneration formulation system is constructed. Compared to traditional petrochemical regenerators, experimental data shows that due to the excellent penetration ability and high flash point characteristics of the bio-based regenerator, it can achieve instantaneous activation of old asphalt in oil-rich RAP material in a microwave field when combined with steel slag. Compared to traditional mineral oil, the bio-based regenerator improves the low-temperature toughness of the repair material while better assisting polyether-type TPU in forming a continuous modified network in the molten state. This allows the repair block to reach the strength requirements for open traffic within 15-20 minutes, and improves long-term anti-aging performance by more than 15%.

[0039] The activation mechanism of microwave-heated repair blocks: Fe3O4 metal oxide in steel slag is an excellent microwave absorber, which can quickly convert microwave energy into heat energy, causing the repair block to heat up uniformly from the inside. After rapidly reaching above 150°C, the TPU particles completely melt and rapidly mix and diffuse with the surrounding asphalt to form a homogeneous, high-toughness TPU-modified asphalt mortar, making the entire mixture a castable mortar with good fluidity.

[0040] To fully verify the feasibility and accuracy of this application, we designed two implementation methods: Example 1 is used to verify the general effectiveness of the preparation method of the repair block; Example 2 is used to verify the influence of molding pressure on the preparation method of the repair block; Example 3 simulates actual engineering application scenarios.

[0041] Example 1: Effect of different TPU doping amounts This set of examples aims to explore the optimal dosage range of TPU particles. Other components were kept constant, only the following modifications were made. Variable TPU content.

[0042] Raw materials: 70# road petroleum asphalt, bio-based regenerator, oil-rich RAP with 8.5% old asphalt content, steel slag with a particle size between 4.75mm and 9.5mm, limestone powder, and polyether-type TPU particles with a particle size of 2-3mm.

[0043] Mixing process: All adopt the "dry method" process of first dry mixing TPU and aggregate for 20 seconds, then adding asphalt and recycling agent and wet mixing for 60 seconds.

[0044] Molding: All samples were molded into small repair blocks at room temperature using the static pressing method (pressure 1.0 MPa).

[0045] Performance Testing: All prepared mixtures were activated by microwave heating (10kW, 5 minutes), and their key performance indicators were tested. See Table 1 below: Table 1. Comparison of Components and Performance Test Results in Example 1 Analysis and Conclusion: Due to the addition of TPU, the low-temperature crack resistance, high-temperature stability, and water stability of all embodiments were superior to those of Comparative Example 1 (without TPU).

[0046] When the TPU content is 2.0% (Examples 1-2), the various properties reach the best balance, with the best low-temperature crack resistance and water stability, and the high-temperature performance reaches 6720 cycles / mm, achieving a balance between rigidity and flexibility.

[0047] When the TPU content increases to 5.0% (Examples 1-3), although the dynamic stability continues to improve, some TPU may not be completely melted and dispersed, resulting in a decrease in interfacial bonding quality and a slight decline in low-temperature crack resistance and water stability. Considering all performance aspects, a TPU content of 1%-3% is the preferred range, with 2% being optimal.

[0048] Example 2: The Influence of Different Molding Pressures This set of embodiments aims to explore the optimal molding pressure of prefabricated repair blocks to balance handling strength and microwave activation efficiency.

[0049] Raw materials: 70# road petroleum asphalt, oil-rich RAP with 8.5% old asphalt content, bio-based regenerator, steel slag with a particle size between 4.75mm and 9.5mm, and polyether-type TPU particles with a particle size of 2-3mm.

[0050] Mixing process: All adopt the "dry method" process of first dry mixing TPU and aggregate for 20 seconds, then adding asphalt and recycling agent and wet mixing for 60 seconds.

[0051] Molding: All samples were molded into small repair blocks at room temperature using the static pressing method (pressures of 0.5, 1.0, and 3.0 MPa, respectively).

[0052] Performance testing: All prepared mixtures were activated by microwave heating (10kW, 5 minutes), and their key performance indicators were tested. The results are shown in Table 2 below.

[0053] Table 2 Comparison of Parameters and Performance Test Results for Example 2 Analysis and Conclusion: Because molding pressure directly affects the density of the repair block. If the pressure is too low (0.5 MPa), the repair block will be too weak. Insufficient pressure hinders storage and transportation. At a pressure of 1.0 MPa, the repair block possesses sufficient handling strength, and its loose internal structure facilitates microwave energy penetration and vapor escape, achieving rapid and uniform activation, resulting in optimal performance. Excessive pressure (3.0 MPa) leads to an overly dense repair block, making it difficult for microwaves to quickly penetrate and heat the interior, resulting in prolonged and uneven activation times. The presence of undercooked material inside also reduces low-temperature crack resistance and water stability. Therefore, low-pressure molding at around 1.0 MPa is crucial in this application.

[0054] Example 3: A comprehensive comparison with traditional processes: This set of embodiments is intended to compare the best embodiment of this application with two conventional processes to highlight the overall advantages of this application.

[0055] Raw materials: 70# road petroleum asphalt, oil-rich RAP with 8.5% old asphalt content, bio-based regenerator, steel slag with a particle size between 4.75mm and 9.5mm, limestone mineral powder, and polyether-type TPU particles with a particle size of 2-3mm.

[0056] Mixing process: All adopt the "dry method" process of first dry mixing TPU and aggregate for 20 seconds, then adding asphalt and recycling agent and wet mixing for 60 seconds.

[0057] Molding: All samples were molded into small sizes at room temperature using a hydrostatic pressing method (pressure 1.0 MPa). Repair the patch.

[0058] Performance testing: The prepared mixtures were activated by microwave heating (10kW, 5 minutes), and their key performance indicators were tested, as shown in Table 3.

[0059] Table 3 Comparison of the Best Embodiment of this Application and Two Traditional Processes Analysis and Conclusion: Thanks to the adoption of the "dry TPU" process, this application comprehensively surpasses traditional wet SBS modified and cold patch materials in key road performance aspects such as low-temperature crack resistance, high-temperature stability, and water stability.

[0060] By introducing "steel slag" as a microwave sensitive agent and combining it with the product form of "prefabricated repair blocks," this application has achieved a revolutionary improvement in construction efficiency and effectively solved the industry's technical problem of short storage period for hot-mixed materials.

[0061] Ultimately, this application has achieved a synergistic breakthrough in the three dimensions of high performance, high efficiency, and green environmental protection, and its technical effect has an overwhelming and significant improvement over the existing technology.

[0062] See Figure 1 As shown in the embodiment of this application, a method for constructing asphalt pavement pothole repair blocks includes the following steps: On-site preparation: Clean the potholes; to further improve adhesion, apply a thin layer of emulsified asphalt as a tack coat inside the cleaned potholes; calculate the number of repair blocks required based on the pothole volume. Microwave activation: Place the repair block into a heating box, and then place the heating box into a microwave oven and heat for 3-8 minutes; utilize the wave absorption properties of steel slag to raise the internal temperature of the repair block until the polyether-type TPU particles melt, obtaining a molten mixture; the heating box is a microwave-resistant engineering plastic heating box.

[0063] When using a 10kW microwave oven, the heating time can be set to 5 minutes.

[0064] Casting and Molding: Quickly pour the molten mixture from the heating chamber into the cleaned pit and level it with a scraper. For the edges and joints of the pit, a small tamper or manual compaction can be used to enhance the density of the interface bond. Due to the toughening effect of TPU, the mixture has sufficient initial strength when cooled to about 90°C, and traffic can be opened within 15-20 minutes after casting.

[0065] Because this application abandons the traditional "wet" modification process and creatively adopts a "dry" direct modification process... Next, solid TPU granules are premixed with aggregates. This process completely eliminates the need for complex, expensive, and energy-intensive high-temperature, high-speed shear modification equipment and procedures, allowing the production line to be implemented in any conventional asphalt mixing plant, significantly lowering the industrialization threshold and production costs. Simultaneously, because the TPU granules avoid prolonged high-temperature shear stress during pre-modification, their polymer chain structure is fully preserved. This allows their inherent high elasticity, high toughness, and other superior properties to be "stored" almost without loss in the precast repair blocks and completely released upon final use, solving the technical pain point of polymer pre-degradation in wet processes.

[0066] This invention specifically selects steel slag as a crucial component of the aggregate and designs it in synergy with the "dry TPU" and "microwave heating" processes. The steel slag not only serves as a hard aggregate, but its contained metal oxides (such as Fe3O4) also act as highly efficient microwave sensitive agents, capable of instantly and uniformly converting microwave energy into heat energy, achieving "volume heating" of the repair material from the inside out. This heating method allows the TPU particles dispersed in the mixture to melt synchronously and rapidly, thus forming a homogeneous and continuous three-dimensional polymer network structure with the asphalt in a very short time (approximately 3-8 minutes) at the construction site. This achieves a perfect transformation of the mixture from a "rigid precast block" to a "high-toughness castable," with final performance far exceeding that of traditional hot-mix asphalt.

[0067] Due to the synergistic effect of the aforementioned "dry TPU" and "microwave activation," the repair material (repair block) prepared in this application exhibits an exceptionally superior balance of high and low temperature performance after construction: the continuous network formed by TPU endows the material with extraordinary flexibility and crack resistance (manifested as extremely high low-temperature bending strain), while the steel slag and RAP material together provide stable skeletal support, ensuring excellent high-temperature rutting resistance. Simultaneously, the rapid and uniform microwave heating completely avoids the problems of surface asphalt aging and insufficient internal heat generation caused by traditional external heating methods, thus ensuring the uniformity and reliability of the quality of each repair.

[0068] Because this application designs the final product as a low-pressure molded repair block, the product achieves standardization, commercialization, and portability. It can be stored, transported, and sold at room temperature for extended periods, just like ordinary building materials, completely solving the industry problem of short shelf life and the need for insulated transportation of hot-mix asphalt mixtures. This not only provides highway maintenance departments with a "ready-to-use" rapid-response material, greatly improving the efficiency of handling routine maintenance tasks such as minor potholes, but also creates a completely new material sales and supply model, laying a solid foundation for the commercial promotion of repair materials.

[0069] Since the formulation system of this application uses RAP material and steel slag as the main aggregates, with a total admixture content of over 80%, it not only achieves all high-performance indicators, but also greatly promotes the high-value-added resource utilization of solid waste in road engineering, which is in line with the green and circular sustainable development strategy and has significant environmental and social benefits.

[0070] In summary, this application, through the organic integration of three core innovations—"dry TPU process," "microwave activation of steel slag," and "prefabricated repair block product form"—successfully solves multiple long-standing challenges such as high performance, high efficiency, low cost, environmental friendliness, and convenient construction within a single technical solution, providing a complete and highly competitive road repair solution.

[0071] The above description is merely a preferred embodiment of this specification and is not intended to limit this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of protection of this specification.

Claims

1. A method for preparing an asphalt pavement pothole repair block, characterized in that, Includes the following steps: S1. Raw material preparation and pretreatment: Prepare aggregates, base asphalt, recycling agent, mineral powder and low melting point polyether TPU particles; preheat the aggregates to 120-160℃, and dry the polyether TPU particles; S2. Dry mixing: Put the preheated aggregate and the dried polyether TPU granules into a forced intermittent mixing pot and dry mix for 50-70 seconds; S3. Wet mixing: Add base asphalt and recycling agent heated to 150-165℃ to the forced intermittent mixing pot and wet mix for 50-70 seconds, then add mineral powder and continue mixing for 80-100 seconds to obtain the mixture; S4. Repair block molding: Quickly transfer the mixed material into the mold, statically press it for 20-35 seconds under a low pressure of 0.5-3MPa, and after demolding and cooling, a repair block with an open pore structure is obtained.

2. The method for preparing asphalt pavement pothole repair blocks according to claim 1, characterized in that, The aggregate is composed of oil-rich RAP material and steel slag; the recycling agent is 3%-8% of the mass of old asphalt contained in the oil-rich RAP material.

3. The method for preparing asphalt pavement pothole repair blocks according to claim 1, characterized in that, The polyether-type TPU particles have a particle size of 1-4 mm, a melt index of 15-25 g / 10 min, and a melting point of 120-150 °C.

4. The method for preparing asphalt pavement pothole repair blocks according to claim 1, characterized in that, In step S1, the drying process involves drying the polyether-type TPU particles at 60℃-80℃ for 2-4 hours until their moisture content is below 0.1%.

5. The method for preparing asphalt pavement pothole repair blocks according to claim 1, characterized in that, In step S4, the pressure is preferably 1.0 MPa-2.0 MPa.

6. The method for preparing asphalt pavement pothole repair blocks according to claim 1, characterized in that, In step S4, the mold is a rectangular mold or a cylindrical mold.

7. The method for preparing asphalt pavement pothole repair blocks according to claim 1, characterized in that: In step S4, the mass percentage of the polyether-type TPU particles in the repair block is 1%-5%, and the mass percentage of the aggregate is ≥90%.

8. A method for constructing asphalt pavement pothole repair blocks, characterized in that, The repair block prepared according to claim 7 is used in the following steps: On-site preparation: Clean the pit and calculate the number of repair blocks needed based on the volume of the pit; Microwave activation: Place the repair block in a heating box and then place the heating box in a microwave oven to heat for 3-8 minutes; utilize the wave absorption properties of steel slag to heat the inside of the repair block until the polyether-type TPU particles melt, thus obtaining a molten mixture; Casting and molding: Quickly pour the molten mixture in the heating box into the cleaned pit and level it with a scraper.

9. The construction method for asphalt pavement pothole repair blocks according to claim 8, characterized in that, Apply a thin layer of emulsified asphalt as a tack coat to the cleaned pit.

10. The construction method for asphalt pavement pothole repair blocks according to claim 8, characterized in that, The heating box is a microwave-resistant engineering plastic heating box, and the microwave oven has a power of ≥10kW.

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