Method for designing dosage of metal fiber in asphalt pavement with active ice and snow melting of surface layer

Abstract

The application discloses a surface heating active ice and snow melting asphalt pavement metal fiber mixing amount design method and relates to the heating field of asphalt concrete. The active ice and snow melting asphalt pavement is obtained by adding a metal material into asphalt mixture as a microwave reflecting material at a certain proportion as a mixing amount; a pavement material composition design method is provided; a microwave surface layer energy retention model is established through a microwave heating test; key parameters such as a reflection coefficient and an energy retention rate are included; key indexes such as a microwave surface layer utilization rate, an ice melting efficiency factor and a critical mixing amount efficiency are introduced; test measurement and data fitting are combined; and the influence of the metal mixing amount on the microwave energy distribution is quantitatively analyzed. The application optimizes the composition of the asphalt concrete pavement material, guarantees the pavement structure performance, significantly improves the absorption and conversion efficiency of the microwave energy on the pavement surface, realizes the high-efficiency and energy-saving heating effect, and provides a scientific and efficient solution for the material design of the active ice and snow melting asphalt pavement.

Description

Technical Field

[0001] This invention relates to the field of asphalt concrete heating technology, specifically to a method for designing the amount of metal fiber admixture in active ice-melting asphalt pavement with surface heating. Background Technology

[0002] Traditional snow and ice melting technologies rely heavily on physical or chemical methods, such as spreading de-icing agents, mechanical removal, or electric de-icing. While these methods have addressed road icing to some extent, they also have significant limitations. The chloride salts in chemical de-icing agents corrode road structures, pollute soil and groundwater, and accelerate the corrosion of bridges and vehicles with long-term use. Mechanical de-icing is inefficient and disruptive to traffic, and struggles to cope with continuous snowfall or extreme low temperatures. Electric de-icing, while offering targeted temperature control, is extremely energy-intensive and requires complex equipment maintenance, hindering large-scale deployment. With increasingly stringent environmental regulations and rising energy conservation demands, the sustainability of these methods faces serious challenges, necessitating the development of more efficient and environmentally friendly alternatives.

[0003] Microwave heating technology, as an emerging method for melting snow and ice, exhibits unique advantages by directionally emitting microwave energy towards the road surface and utilizing the dielectric loss of the material to generate heat. Microwaves can penetrate the ice and snow layer to directly heat the road surface material, avoiding the heat loss problem of traditional methods, and precise temperature control can be achieved by adjusting the emission parameters. However, the practical application of this technology is limited by the absorption efficiency of microwave energy by asphalt concrete. In existing technologies, metal materials (such as steel wool and iron filings) are often added to enhance the microwave absorption performance, but the design of the dosage often relies on experience or trial and error, lacking systematic theoretical guidance. Excessive metal addition causes excessive reflection of microwaves on the surface, preventing energy from effectively penetrating into the interior of the material; insufficient addition allows microwaves to penetrate to the middle and lower layers of the road surface, significantly reducing energy utilization. This extensive design not only wastes energy but may also lead to the deterioration of material mechanical properties due to uneven metal distribution, such as decreased compressive strength and shortened fatigue life. To address the aforementioned issues, it is urgent to establish a doping design method based on the synergistic analysis of electromagnetic theory and material thermal properties. By optimizing the doping ratio of microwave reflective materials, the dynamic balance between surface reflection energy and middle and lower layer penetration energy can be precisely controlled, thereby maximizing microwave energy utilization. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for designing the amount of metal fiber used in active ice-melting asphalt pavement with surface heating, which solves the technical problem that existing technologies cannot achieve a dynamic balance between surface reflection energy and middle and lower layer penetration energy.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for designing the metal fiber content of surface-heated active ice-melting asphalt pavement, wherein the pavement includes a top layer, a middle layer and a bottom layer arranged from top to bottom on a base layer, wherein the top layer is made of asphalt mixture mixed with microwave reflective material, and the middle layer and the bottom layer are made of ordinary asphalt mixture;

[0006] The method for designing the metal fiber doping content includes the following steps:

[0007] S1. Determine the required asphalt type, aggregate, and admixture in the asphalt mixture, and prepare asphalt concrete ice-covered specimens with different amounts of microwave reflective material.

[0008] S11, according to gradient doping ( Asphalt concrete specimens were prepared with a concentration of 1% to 9%, and n sets (n≥4) of parallel samples were prepared for each gradient.

[0009] S12. Calculate the volume of water required to make the ice layer based on the desired ice layer thickness. The density of ice is... =0.9 g / cm³, the density of water =1.0g / cm³;

[0010] S13. Pour water into a leak-proof mold coated with hydraulic oil and place it in a freezer at -T℃ to freeze until the ice layer is completely formed.

[0011] S14. Spray a small amount of water on the surface of the rut plate, place it on the ice layer, and freeze it together with the mold in a freezer at -T℃ until the ice layer and the rut plate specimen are frozen together. Take it out and demold it.

[0012] S2. Measure the reflection coefficient of each icing specimen. and transmission coefficient Calculate the proportion of reflected energy and the proportion of transmitted energy ;

[0013] S3. Calculate the energy retention rate of icing specimens with different doping amounts based on the energy balance equation:

[0014]

[0015] S4, with a certain power Microwave irradiation was applied to ice-covered specimens, and changes in ice thickness were monitored using a laser displacement sensor. Calculate the ice melting efficiency factor ;

[0016] S41. Calculate the ice melting rate using changes in ice thickness and microwave heating time:

[0017]

[0018] S42. Calculate the ice melting efficiency factor:

[0019]

[0020] in =334 J / g is the latent heat of ice melting;

[0021] S5. Calculate based on the critical doping efficiency index. To obtain the optimal doping amount, the value of is determined.

[0022]

[0023] when When the dosage is reached, the corresponding dosage is the optimal dosage.

[0024] S6. Select the option that satisfies the requirements. Maximum and The dosage is used as the final design parameter for active ice and snow melting asphalt pavement;

[0025] Furthermore, the microwave frequency and power used by the vector network analyzer in step S2 when detecting the reflection coefficient and incident coefficient need to be consistent with the microwave frequency and power in step S4.

[0026] Furthermore, the proportion of reflected energy mentioned in step S2 is The proportion of transmitted energy is ;

[0027] Furthermore, the critical doping efficiency index mentioned in step S5 The basis for judgment is:

[0028] when When the doping amount is insufficient, energy penetration dominates, and most microwaves pass through the ice layer and the top layer, remaining in the middle layer and below without heating the top layer. In this case, the doping amount of metal reflective material should be increased appropriately.

[0029] when When the doping amount is too high, energy reflection becomes dominant. Too much metal will form a metal shielding layer on the surface of the upper layer, causing most of the microwaves to be reflected directly into the air on the first reflection of the upper layer without heating the upper layer. In this case, the doping amount of metal reflective material should be reduced appropriately.

[0030] when At this point, the sum of the reflected and transmitted energy of the microwaves reaches its minimum. At this time, most of the microwaves are continuously reflected inside the upper layer, resulting in an increase in the temperature of the upper layer, which corresponds to the optimal doping amount of the metal reflective material.

[0031] The application of this invention is a method for designing the metal fiber content in active ice-melting asphalt pavements with surface heating, specifically including: adjusting the metal admixture content... This allows for efficient retention of microwave energy on the surface, reducing reflection and penetration losses. By combining critical admixture efficiency indicators, the optimal metal admixture dosage is precisely determined, enabling the road surface to achieve the optimal balance between ice melting efficiency and energy utilization under fixed microwave parameters.

[0032] By employing the above technical solution, the present invention provides a method for designing the metal fiber content of surface-heated active ice-melting asphalt pavement, which has at least the following beneficial effects:

[0033] 1. This invention scientifically controls the doping ratio of microwave reflective materials to balance the surface absorption, reflection, and penetration of microwave energy, significantly improving energy utilization efficiency and greatly reducing energy consumption while achieving rapid ice melting. By optimizing the doping design, energy reflection loss and ineffective penetration are reduced, ensuring that microwave energy is concentrated on the surface and efficiently converted into heat energy. This avoids the material performance degradation caused by excessive doping in traditional methods and solves the energy waste problem caused by insufficient doping, providing reliable support for energy-saving and environmentally friendly ice and snow melting technology.

[0034] 2. This invention, combining theoretical models and experimental verification, establishes a systematic method for designing the doping levels of microwave reflective materials. This method can accurately select the optimal parameter combination that balances energy absorption efficiency, material durability, and construction feasibility. By quantifying the correlation between microwave energy distribution and material properties, it overcomes the blindness of traditional trial-and-error methods, shortens the design cycle, and reduces development costs, providing scientific guidance for the engineering application of microwave heating for melting ice and snow.

[0035] 3. This invention fully leverages the potential of microwave reflective materials in improving de-icing rates and reducing energy consumption. By dynamically optimizing the balance between energy absorption and loss, it achieves the dual goals of maximizing de-icing efficiency and minimizing energy consumption. Compared to traditional de-icing technologies, this invention achieves superior de-icing effects with lower energy consumption, promoting the sustainable development of green road construction and intelligent transportation systems, and providing an efficient and environmentally friendly technical solution for addressing extreme climate challenges. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0037] Figure 1 This is a flowchart of the metal doping design calculation method of the present invention;

[0038] Figure 2This is a schematic diagram of the upper, middle, and lower layers of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the microwave heating ice-melting device of the present invention;

[0040] In the picture:

[0041] 1. Microwave heating layer; 2. Middle and lower layers; 3. Steel wool; 4. Asphalt mixture; 5. Ice layer; 6. Microwave heating equipment; Detailed Implementation

[0042] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This will allow for a full understanding of how the present application uses technical means to solve technical problems and achieve technical effects, and to facilitate its implementation.

[0043] Please refer to Figures 1-3 This illustration shows a specific implementation of this embodiment. This embodiment focuses on the design method of metal fiber admixture for active ice-melting asphalt pavement with surface heating. By scientifically controlling the admixture ratio of microwave reflective materials (such as steel wool), it achieves efficient retention and conversion of microwave energy on the pavement surface, breaking through the bottlenecks of high energy loss and low ice-melting efficiency in traditional technologies.

[0044] This embodiment designs multiple microwave heating experiments to systematically analyze the influence of steel wool content (1%-9%) on microwave reflection coefficient, transmission coefficient, and surface energy retention rate. Combining the heating efficiency factor and critical content efficiency index, a quantitative correlation model of "content-energy distribution-ice melting efficiency" is established. This model dynamically balances the surface absorption, reflection, and penetration of microwave energy, ensuring that energy is concentrated for ice melting while avoiding reflection loss or ineffective penetration due to improper content.

[0045] To achieve the above technical effects, this embodiment proposes a design method for the metal fiber content of active ice-melting asphalt pavement with surface heating. The pavement includes a top layer, a middle layer and a bottom layer set from top to bottom on the base layer. The top layer is made of asphalt mixture mixed with microwave reflective material, and the middle layer and the bottom layer are made of ordinary asphalt mixture.

[0046] The method for designing the metal fiber doping content includes the following steps:

[0047] S1. Select AC-13 as the mixture type, use 70# matrix asphalt basalt aggregate (including coarse and fine aggregates) as raw material, and steel wool as an admixture to prepare asphalt concrete icing specimens with different microwave reflective material admixtures. The size of the asphalt concrete specimen is 3cm*30cm*30cm, and the size of the iced specimen is 5cm*30cm*30cm. The specific preparation steps are as follows:

[0048] S11. According to the gradient dosage (mass ratio to asphalt) Asphalt concrete specimens were prepared at (1%, 3%, 5%, 7%, 9%), with 4 parallel samples for each gradient;

[0049] S12. Given that the density of ice is... =0.9 g / cm³, the density of water =1.0g / cm³ To make an ice layer with a thickness of 2cm, the required ice layer volume is 2cm*30cm*30cm, and the required water volume is 1620cm³.

[0050] S13. Pour 1620 cm³ of water into a leak-proof mold coated with hydraulic oil. The mold size is 31 cm * 31 cm, slightly larger than the size of the rutted slab specimen. Place the water-filled mold in a freezer at -15°C for 24 hours until the ice layer is completely formed.

[0051] S14. Spray a small amount of water on the surface of the specimen, place it on the ice layer, and freeze it together with the mold in a freezer at -15℃ for 5 hours to freeze the ice layer and the rut plate specimen together. Take it out and demold it.

[0052] S2. The reflection coefficient of each icing specimen was measured using a vector network analyzer with a frequency of 2.45 GHz and a power of 800 W. and transmission coefficient ,according to , Calculate the percentage of reflected energy and the proportion of transmitted energy ;

[0053] S3. Calculate the energy retention rate of icing specimens with different doping amounts based on the energy balance equation:

[0054]

[0055] The average value of the test results for the four parallel samples is shown in Table 1.

[0056]

[0057] Table 1 Calculated values ​​of energy retention rate

[0058] Based on the data in Table 1, the fitted curve is obtained as follows:

[0059]

[0060] S4. In an outdoor environment with a temperature of 0℃, the ice-covered specimen is irradiated with a microwave at a frequency of 2.45GHz and a power of 800W, and the change in ice thickness is monitored by a laser displacement sensor. Ice thickness data were recorded every 5 seconds, and the average value of the data from the four parallel samples was calculated. The specific values ​​are shown in Table 2.

[0061] steel wool content 1% 3% 5% 7% 9% 0s 2 2 2 2 2 5s 1.99 1.95 1.9 1.92 1.95 10s 1.97 1.89 1.8 1.83 1.88 15s 1.94 1.82 1.69 1.74 1.8 20s 1.9 1.74 1.58 1.65 1.72 25s 1.86 1.65 1.46 1.56 1.64 30s 1.81 1.56 1.34 1.47 1.56 35s 1.76 1.46 1.22 1.38 1.48 40s 1.7 1.36 1.1 1.29 1.4 45s 1.64 1.25 0.98 1.2 1.32 50s 1.57 1.14 0.86 1.1 1.24 55s 1.5 1.03 0.74 1.01 1.16 60s 1.43 0.92 0.62 0.92 1.08 65s 1.35 0.81 0.5 0.83 1

[0062] Table 2. Ice thickness variation table

[0063] S41. Calculate the ice melting rate using changes in ice thickness and microwave heating time:

[0064]

[0065] S42. Calculate the ice melting efficiency factor:

[0066]

[0067] in =334 J / g is the latent heat of ice melting; the calculation results are shown in Table 3:

[0068]

[0069] Table 3 Melting efficiency factor

[0070] S5. Calculate based on the critical doping efficiency index. To obtain the optimal doping amount, the value of is determined.

[0071]

[0072] when At that time, the corresponding dosage is the optimal dosage; the critical dosage efficiency index mentioned in step S5 The basis for judgment is:

[0073] when When the doping amount is insufficient, energy penetration dominates, and most microwaves pass through the ice layer and the top layer, remaining in the middle layer and below without heating the top layer. In this case, the doping amount of metal reflective material should be increased appropriately.

[0074] when When the doping amount is too high, energy reflection becomes dominant. Too much metal will form a metal shielding layer on the surface of the upper layer, causing most of the microwaves to be reflected directly into the air on the first reflection of the upper layer without heating the upper layer. In this case, the doping amount of metal reflective material should be reduced appropriately.

[0075] when At this point, the sum of the reflected and transmitted energy of the microwaves reaches its minimum. At this time, most of the microwaves are continuously reflected inside the upper layer, resulting in an increase in the temperature of the upper layer, which corresponds to the optimal doping amount of the metal reflective material.

[0076] S6. Select the option that satisfies the requirements. Maximum and The dosage of steel wool is used as the final design parameter for active ice and snow melting asphalt pavement. According to the test data, the optimal dosage is 5%.

[0077] The application of this invention is a method for designing the metal fiber content in active ice-melting asphalt pavements with surface heating, specifically including: adjusting the metal admixture content... This allows for efficient retention of microwave energy on the surface, reducing reflection and penetration losses. By combining critical admixture efficiency indicators, the optimal metal admixture dosage is precisely determined, enabling the road surface to achieve the optimal balance between ice melting efficiency and energy utilization under fixed microwave parameters.

[0078] The above embodiments provide a detailed description of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for designing the metal fiber content in surface-heating active ice-melting asphalt pavement, characterized in that, The road surface includes a top layer, a middle layer, and a bottom layer disposed from top to bottom on a base layer. The top layer is made of asphalt mixture mixed with microwave reflective material, and the middle layer and the bottom layer are made of ordinary asphalt mixture. The method for designing the metal fiber doping content includes the following steps: S1. Determine the required asphalt type, aggregate, and admixture in the asphalt mixture, and prepare asphalt concrete ice-covered specimens with different amounts of microwave reflective material. S11, according to gradient doping =1%~9%, prepare asphalt concrete specimens, n sets of parallel samples for each gradient, n≥4; S12. Calculate the volume of water required to make the ice layer based on the desired ice layer thickness. The density of ice is... =0.9 g / cm³, the density of water =1.0g / cm³; S13. Pour water into a leak-proof mold coated with hydraulic oil and place it in a freezer at -T℃ to freeze until the ice layer is completely formed. S14. Spray a small amount of water on the surface of the rut plate, place it on the ice layer, and freeze it together with the mold in a freezer at -T℃ until the ice layer and the rut plate specimen are frozen together. Take it out and demold it. S2. Measure the reflection coefficient of each icing specimen. and transmission coefficient Calculate the proportion of reflected energy and the proportion of transmitted energy ; S3. Calculate the energy retention rate of icing specimens with different doping amounts based on the energy balance equation: ； S4, with a certain power Microwave irradiation was applied to ice-covered specimens, and changes in ice thickness were monitored using a laser displacement sensor. Calculate the ice melting efficiency factor ; S41. Calculate the ice melting rate using changes in ice thickness and microwave heating time: ； S42. Calculate the ice melting efficiency factor: ； in =334 J / g is the latent heat of ice melting; S5. Calculate based on the critical doping efficiency index. To obtain the optimal doping amount, the value of is determined. ； when When the dosage is reached, the corresponding dosage is the optimal dosage. S6. Select the option that satisfies the requirements. Maximum and The dosage is used as the final design parameter for active ice and snow melting asphalt pavement.

2. The method according to claim 1, characterized in that, The microwave frequency and power used by the vector network analyzer in step S2 to detect the reflection coefficient and incident coefficient need to be consistent with the microwave frequency and power in step S4.

3. The method according to claim 1, characterized in that, The proportion of reflected energy in step S2 is The proportion of transmitted energy is .

4. The method according to claim 1, characterized in that, The critical doping efficiency index mentioned in step S5 The basis for judgment is: when When the doping amount is insufficient, energy penetration dominates, and most microwaves pass through the ice layer and the top layer, remaining in the middle layer and below without heating the top layer. In this case, the doping amount of metal reflective material should be increased appropriately. when When the doping amount is too high, energy reflection becomes dominant. Too much metal will form a metal shielding layer on the surface of the upper layer, causing most of the microwaves to be reflected directly into the air on the first reflection of the upper layer without heating the upper layer. In this case, the doping amount of metal reflective material should be reduced appropriately. when At this point, the sum of the reflected and transmitted energy of the microwaves reaches its minimum. At this time, most of the microwaves are continuously reflected inside the upper layer, resulting in an increase in the temperature of the upper layer, which corresponds to the optimal doping amount of the metal reflective material.

5. An application of the method as described in any one of claims 1-4, characterized in that, The design method for the metal fiber content of active ice-melting asphalt pavement for surface heating specifically includes: adjusting the metal admixture content... This allows for efficient retention of microwave energy on the surface, reducing reflection and penetration losses. By combining critical admixture efficiency indicators, the optimal metal admixture dosage is precisely determined, enabling the road surface to achieve the optimal balance between ice melting efficiency and energy utilization under fixed microwave parameters.

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