A low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting road surface

Abstract

The present invention discloses a low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting pavement, which belongs to the field of research and development of intelligent and functional pavement materials. The present invention adopts the method of first mixing stainless steel microfilaments with asphalt and mineral powder to add stainless steel microfilaments, and adopts a pre-voltage method and a three-piece electrode layout method designed based on the conductive mechanism. It can give the traditional pavement structure material - asphalt concrete excellent electrical and thermal conductivity while ensuring its excellent mechanical and deformation properties. Then, when connected to an external power supply, the conductive asphalt concrete can be heated and heated by electrothermal conversion according to Joule's law, thereby realizing self-melting of ice and snow on the road surface. The low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting pavement proposed by the present invention can be directly applied to airport runways, parking lots, bridge decks, tunnel entrances and other sections with heavy snow accumulation in the form of full-size conductive asphalt concrete pavement, strip pavement, and overlay layer.

Description

Technical Field

[0001] The invention relates to a low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting road surface, belonging to the field of intelligent / functional road surface materials. Background Art

[0002] Snow and ice on asphalt roads seriously impact the efficient operation of transportation infrastructure (especially airport runways, bridges, and tunnel entrances), socioeconomic development, and have become a common challenge for global road transportation systems. The presence of snow and ice reduces tire-road adhesion to only one-eighth to one-quarter of that on dry roads. This leads to poor driving behavior, such as wheel slippage, deviation, extended braking distances, and brake failure, resulting in frequent traffic accidents and serious casualties. To ensure the safe and efficient operation of transportation infrastructure, addressing the issue of snow and ice on roads is urgent. Traditional methods for snow and ice removal have evolved from manual removal to mechanical shoveling and chemical snow melting (i.e., spreading snow-melting agents). Manual snow and ice removal is inefficient and costly; mechanical shoveling is incomplete and requires expensive equipment; and the chlorides in snow-melting agents pollute soil and water sources and are corrosive to road surface materials. Consequently, researchers and engineers have developed numerous new snow and ice removal methods and technologies, incorporating advanced materials, new products, new machines / equipment, and innovative concepts. Among them, the conductive asphalt concrete ice and snow melting method has the advantages of not requiring traffic interruption, not affecting the integrity of the road structure, timely melting of ice and snow, and easy preparation, which has attracted great attention.

[0003] The addition of conductive fillers can impart excellent electrical and thermal conductivity to asphalt concrete, a traditional pavement structural material, while maintaining its excellent mechanical and deformation properties. Furthermore, when connected to an external power source, the conductive asphalt concrete can heat up through electrothermal conversion according to Joule's law, achieving self-melting ice and snow on the pavement. Furthermore, conductive asphalt concrete pavements can be completed using conventional mixing and compaction processes, and their asphalt concrete matrix can be a fine-grained asphalt concrete or asphalt mastic macadam mixture for the upper layer, an anti-skid wear layer or an ultra-thin wear layer, asphalt surface treatment for quick repair, and an asphalt fine sand overlay. In other words, it is widely applicable to substrates with different aggregate gradations. However, previous studies have found that the electrical heating performance of conductive asphalt concrete is limited by its resistivity, which depends on the type, dosage, and size of the added conductive filler. Currently, single carbon fiber addition or a combination of carbon fiber and other conductive fillers (primarily graphene, graphite, and steel slag) is commonly used to reduce the resistivity and achieve the desired heating effect. However, carbon fiber is expensive and mostly exists in the form of clusters, which makes it difficult to disperse the fibers, the dispersion process is complicated, and many invalid fibers will be produced (i.e., fibers that are ineffective in improving the resistivity of asphalt concrete). Therefore, only a high dosage of carbon fiber can significantly change the conductivity of asphalt concrete, but this will inevitably lead to high costs for materials and construction. The composite use of graphene / graphite / steel slag and carbon fiber can reduce the dosage of carbon fiber, but the high price of graphene and the high dosage of graphite / steel slag will lead to greater cost problems and easily have a negative impact on the road performance of asphalt concrete. In addition, cheap steel wool fiber is also widely used in conductive asphalt concrete, but its effect on resistivity modification is poor, and it has defects such as high dosage, inconsistent length and diameter, need for manual cutting, and difficulty in dispersion. In summary, the field of electrothermal conductive asphalt concrete still has problems such as high dosage of conductive filler, low conductivity, and high cost, which seriously restricts the application of electrothermal ice and snow melting of conductive asphalt concrete. Summary of the Invention

[0004] To address these issues, the present invention aims to provide an electric snow-melting pavement based on stainless steel microfilament conductive asphalt concrete, which boasts low resistivity, low conductive filler content, low cost, and excellent snow-melting performance. The conductive filler used in the conductive asphalt concrete is low-content stainless steel microfilaments with micron-level diameters, a stainless matrix, a high aspect ratio, high flexibility, high conductivity, and excellent mechanical properties. By applying a voltage to the stainless steel microfilament conductive asphalt concrete using a pre-applied voltage method based on a conductive mechanism (tunneling effect) and a three-electrode arrangement, the concrete is efficiently heated and heated using its excellent electrothermal conversion properties, thereby rapidly melting snow and ice.

[0005] The technical solution of the present invention:

[0006] A low-content stainless steel microwire conductive asphalt concrete electric heating snow-melting pavement is disclosed. Stainless steel microwires are added to the asphalt concrete, and voltage is applied to the stainless steel microwire conductive asphalt concrete using a pre-voltage method designed based on the conductive mechanism and a three-piece electrode layout method.

[0007] The stainless steel microwire is made of molybdenum-chromium stainless steel with high chloride ion corrosion resistance, has a diameter of 10-30 μm, a length of 6-15 mm, an elongation greater than 1%, a tensile strength greater than 780 MPa, and a content of 0.7-1% of the volume of asphalt in asphalt concrete.

[0008] The stainless steel microwires are added in a manner of first mixing the stainless steel microwires, asphalt and mineral powder, and then mixing them with aggregate.

[0009] Furthermore, the mixing process is as follows: the aggregate is preheated to 160-170°C for 1.5-2 hours; the asphalt, mineral powder, and stainless steel microwires are preheated to 150-160°C for 1.5-2 hours; the stainless steel microwires, asphalt, and mineral powder are then mixed and stirred at 150-160°C (mixing temperature) for 90-120 seconds, the aggregate is then added, stirred at 150-160°C (mixing temperature) for 90-120 seconds, and then formed at 140-150°C (forming temperature) with 75-100 compaction cycles. The stainless steel microwire conductive asphalt concrete can achieve optimal mixing and conductive effects under existing mixing methods.

[0010] Furthermore, the matrix of the asphalt concrete used (composed of a mixture of asphalt, mineral powder, and aggregate) is extremely wide and has fewer restrictions. It can be a fine-grained asphalt mixture (i.e., a nominal maximum particle size of 9.5 or 13.2 mm), an anti-skid wear layer or an ultra-thin wear layer, or an asphalt surface treatment for rapid repair and an asphalt fine sand overlay.

[0011] Furthermore, the three-piece electrode layout method is to place three stainless steel mesh electrodes on both sides and the middle position (i.e., left, middle, and right) of the stainless steel microfilament conductive concrete electric heating snow-melting road surface, which can increase the overlap probability of the stainless steel microfilaments between the electrodes, thereby improving the conductive properties and electrothermal properties of the conductive asphalt concrete; the single hole side length of the stainless steel mesh electrode is 2-5mm.

[0012] Furthermore, the pre-voltage method designed based on the conductive mechanism is to pre-apply instantaneous voltage to the left and middle electrodes, and the middle and right electrodes in turn before formally applying the set voltage to start electrothermal melting of ice and snow, and then cut off the power, and then formally apply the set voltage to the left and right electrodes; this method can utilize the breakdown effect of the interface capacitance (or tunnel effect) between stainless steel microwires, thereby significantly improving the conductive properties and electrothermal properties of conductive asphalt concrete.

[0013] The low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting pavement can be used in the form of conductive asphalt concrete full-size pavement, strip pavement, and overlay layer in sections with heavy snow accumulation such as airport runways, parking lots, bridge decks, and tunnel entrances.

[0014] The present invention improves the electrical conductivity of asphalt concrete and gives it excellent electric heating and snow-melting performance by adding stainless steel microwires in a way that they are first mixed with asphalt and mineral powder, and adopts a pre-voltage method and a three-piece electrode layout method designed based on the conductive mechanism. Its main action mechanism includes the following four aspects: 1) Stainless steel microwires with micron-level diameter, stainless matrix, high aspect ratio, high flexibility, high electrical conductivity, high thermal conductivity and high mechanical properties have extremely free spatial distribution such as bending and orientation, and are easy to form a three-dimensional overlapping conductive network in asphalt concrete, which can give asphalt concrete long-term stable high electrical conductivity and thermal conductivity at a low dosage, and will not cause tire punctures; 2) When stainless steel microwires are first mixed with asphalt and mineral powder, the stainless steel microwires with a soft texture can be moved along with the asphalt The swirling flow of the mortar makes the stainless steel microwires smooth and organized; at the same time, the stainless steel microwires are more easily evenly dispersed in the asphalt concrete due to the filling effect of the asphalt mortar on the gaps between the stainless steel microwires. 3) The conductive path of the stainless steel microwire conductive asphalt concrete is composed of the pure resistance equivalent to the microwire overlap path and the capacitor equivalent to the interfacial capacitance (tunnel effect) between the microwires. When the pre-applied voltage is high enough, it can "break down" the interfacial capacitor between the microwires (i.e., the tunnel effect), reducing the matrix resistance to a certain extent, or in other words, the high voltage temporarily opens part of the conductive path. 4) Based on the conductive mechanism, when a three-piece electrode layout is used, the presence of the intermediate electrode network will greatly increase the probability of stainless steel microwires overlapping to form a three-dimensional conductive network and reduce the tortuosity and length of the conductive path, thereby significantly improving the conductive performance. The combined effect of these four steps, reasons, or methods gives low-content stainless steel microwire conductive asphalt concrete excellent conductive properties and electric heating and snow melting performance.

[0015] Beneficial effects of the present invention: The present invention improves the electrical conductivity of asphalt concrete and gives it excellent electric heating snow and ice melting performance by adding stainless steel microwires by first mixing them with asphalt and mineral powder, and adopts a pre-voltage method and a three-piece electrode layout method designed based on the conductive mechanism. This overcomes the problems in the field of electrically heated conductive asphalt concrete, such as large amount of conductive filler, low conductivity, high cost, poor snow and ice melting effect (such as long time consumption and low energy utilization). At the same time, low-content stainless steel microwires can be directly incorporated into asphalt concrete, with a simple preparation process and good dispersion performance, without the need for a complex dispersion process. The low-content stainless steel microwire conductive asphalt concrete electric heating snow and ice melting pavement based on the pre-voltage method and the three-piece electrode layout method can be directly applied to airport runways, parking lots, bridge panels, tunnel entrances and other sections with heavy snow accumulation in the form of full-size conductive asphalt concrete pavement, strip pavement, and overlay layer. Its high electrical conductivity, pre-voltage method, and three-piece electrode layout can improve the electrothermal conversion efficiency and ice and snow melting rate. It can also be combined with mechanical snow removal (i.e., first using electric heating to melt the bonding layer between the upper surface and the overlying snow layer, and then using mechanical snow removal to quickly shovel the snow layer) to remove ice and snow with low energy consumption, short time consumption, and low road damage. In addition, the asphalt concrete matrix used can be fine-grained asphalt concrete and asphalt mastic macadam mixture, or it can be an anti-skid wear layer or ultra-thin wear layer, or it can be asphalt surface treatment for rapid repair and asphalt fine sand overlay. Moreover, optimizing the aggregate gradation design is expected to further improve the electrical conductivity and electrothermal performance of stainless steel microfilament conductive asphalt concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the voltage application process of the stainless steel microwire conductive asphalt concrete specimen, including the pre-voltage process and the formal voltage application process.

[0017] Figure 2 Schematic diagram of the electrode layout of the stainless steel microwire conductive asphalt concrete specimen. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0019] The electrothermal ice and snow melting performance tests of stainless steel microfilament conductive asphalt concrete panels were conducted in a laboratory. The test panels used a fine-grained AC asphalt concrete substrate. During the mixing process, 0.7-1 vol% stainless steel microfilaments were first mixed with asphalt and mineral powder at high temperatures (150-160°C) for 90-120 seconds. Aggregate was then added and stirred at high temperatures (150-160°C) for 90-120 seconds. The test panels measured 300 mm × 300 mm × 50 mm. Three stainless steel mesh electrodes were embedded on the left and right sides and in the center of the test panels, with a spacing of 260 mm between the electrodes, 20 mm from the side edges, and 10 mm from the top and bottom edges. To demonstrate the electrothermal ice and snow melting performance of the stainless steel microfilament conductive asphalt concrete, a 50V / 60V DC power supply and pre-applied voltage were applied to the test panels for electrothermal ice and snow melting tests. In the ice melting test, the ice layer thickness was 4 mm (330 g); in the snow melting test, the snow layer was 2 cm (490 g) and 4 cm (980 g) of dense snow (density 0.27 g / cm 3 ), and the test environment was a windless, enclosed space at around -10°C. In the de-icing and snow-melting tests, if the temperature of any thermocouple of the specimen reached 40°C (the maximum heating temperature of the specimen determined based on the softening point of asphalt), the voltage was stopped for 20 minutes (power-off stage), and then the pressure was applied again. The specimen melted the snow in a cycle of power supply and power-off stages (pressurization-depressurization cycle) until the snow layer was completely melted, and the test was terminated. During the test, 7 thermocouples (K series products produced by Omega, with an accuracy of 0.1°C) were pasted or embedded on the upper surface, middle layer and lower surface of the specimen plate to record the temperature data of the specimen in real time during the electric heating de-icing and snow-melting process, and another thermocouple was arranged to record the ambient temperature.

[0020] Example 1

[0021] This embodiment adopts a method of first mixing stainless steel microwires with asphalt and mineral powder, and then adding low-dosage stainless steel microwires with micron-level diameter, stainless matrix, high aspect ratio, high flexibility, high electrical conductivity and high mechanical properties, and adopts a pre-voltage method designed based on the conductive mechanism and a three-piece electrode layout method to give and improve the electrical conductivity of asphalt concrete, and then develops an electric heating snow-melting road surface based on its excellent electrothermal conversion characteristics. It is suitable for use in airport runways, parking lots, bridge panels, tunnel entrances and other sections with heavy snow accumulation in the form of full-size pavements, strip pavements and overlays of conductive asphalt concrete.

[0022] In this embodiment, fine-grained AC-10 asphalt concrete is used as the matrix; the diameter of the stainless steel microwire used is 10 μm, the length is 6 mm, and the admixture amount is 1 vol% of the asphalt volume (equivalent to 0.36% of the mass of the asphalt concrete, i.e. 0.36%); the mixing process is as follows: the aggregate is preheated at 170°C for 2 hours, the stainless steel microwire, asphalt and mineral powder are preheated at 160°C for 2 hours, then the stainless steel microwire is mixed with the asphalt and mineral powder at 160°C for 100 seconds, and then the aggregate is added and stirred for 100 seconds. The molding temperature is 140°C and the compaction times are 85 times; the size of the newly cast road panel of the molding scale is 300mm×300mm×50mm, and stainless steel mesh electrodes of size 260mm×30mm are buried on the left and right sides and the middle position of the panel respectively. The mesh size of the electrode mesh is 2mm×3mm, the distance between the electrodes on both sides is 260mm, the distance from the two side edges is 20mm, and the distance from the upper and lower edges is 10mm. A voltage of 50 V was used to pre-apply voltage to the test piece and to formally apply voltage.

[0023] The test results show (as shown in Table 1) that the low-content stainless steel microfilament conductive asphalt concrete specimens exhibit excellent ice melting performance at a voltage of 50V and a windless environment of -10℃. They can melt 4mm of ice in the electrode area within 180 minutes, with an energy utilization rate of up to 66.49% and a power density of approximately 260.42W / m 2 .

[0024] Example 2

[0025] This embodiment adopts a method of first mixing stainless steel microwires with asphalt and mineral powder, and then adding low-dosage stainless steel microwires with micron-level diameter, stainless matrix, high aspect ratio, high flexibility, high electrical conductivity and high mechanical properties, and adopts a pre-voltage method designed based on the conductive mechanism and a three-piece electrode layout method to give and improve the electrical conductivity of asphalt concrete, and then develops an electric heating snow-melting road surface based on its excellent electrothermal conversion characteristics. It is suitable for use in airport runways, parking lots, bridge panels, tunnel entrances and other sections with heavy snow accumulation in the form of full-size pavements, strip pavements and overlays of conductive asphalt concrete.

[0026] In this embodiment, fine-grained AC-13 asphalt concrete is used as the matrix; the stainless steel microwires used have a diameter of 20 μm and a length of 10 mm, and the admixture amount is 0.75 vol% of the asphalt volume (equivalent to 0.27 wt% of the asphalt concrete mass); the mixing process is as follows: the aggregate is preheated at 163°C for 1.75 hours, the stainless steel microwires, asphalt, and mineral powder are preheated at 150°C for 1.75 hours, and then the stainless steel microwires, asphalt, and mineral powder are mixed at 150°C for 1.75 hours. Mix and stir at 0°C for 90 seconds, then add aggregate and stir for 90 seconds. The molding temperature is 140°C, and the number of compaction cycles is 100. The newly cast road slab has a size of 300mm × 300mm × 50mm. Stainless steel mesh electrodes measuring 260mm × 30mm are embedded on the left and right sides and in the middle of the slab. The mesh size of the electrode mesh is 2mm × 3mm. The spacing between the electrodes is 260mm, and the distance from the two edges is 20mm. The distance from the upper and lower edges is 10mm. A 60V voltage is used for pre-voltage and the main voltage is applied to the specimen.

[0027] The test results show (as shown in Table 1) that the low-content stainless steel microfilament conductive asphalt concrete specimens exhibit excellent ice melting performance at a voltage of 60V and a windless environment of -10℃. They can melt 4mm of ice in the electrode area within 120 minutes, with an energy utilization rate of up to 88.59% and a power density of approximately 685.78W / m 2 .

[0028] Example 3

[0029] This embodiment adopts a method of first mixing stainless steel microwires with asphalt and mineral powder, and then adding low-dosage stainless steel microwires with micron-level diameter, stainless matrix, high aspect ratio, high flexibility, high electrical conductivity and high mechanical properties, and adopts a pre-voltage method designed based on the conductive mechanism and a three-piece electrode layout method to give and improve the electrical conductivity of asphalt concrete, and then develops an electric heating snow-melting road surface based on its excellent electrothermal conversion characteristics. It is suitable for use in airport runways, parking lots, bridge panels, tunnel entrances and other sections with heavy snow accumulation in the form of full-size pavements, strip pavements and overlays of conductive asphalt concrete.

[0030] In this embodiment, fine-grained AC-13 asphalt concrete is used as the matrix; the diameter of the stainless steel microwire used is 20 μm, the length is 15 mm, and the admixture amount is 0.7 vol% of the asphalt volume (equivalent to 0.25% of the mass of the asphalt concrete, i.e. 0.25 wt%); the mixing process is as follows: the aggregate is preheated at 160°C for 1.5 hours, the stainless steel microwire, asphalt and mineral powder are preheated at 150°C for 1.5 hours, and then the stainless steel microwire, asphalt and mineral powder are first mixed at 150°C. The mixture was stirred for 120 seconds, followed by the addition of aggregate and mixing for another 120 seconds. The molding temperature was 150°C, and the number of compaction cycles was 75. The newly cast road slab had a size of 300mm × 300mm × 50mm. Stainless steel mesh electrodes measuring 260mm × 30mm were embedded on the left and right sides and in the middle of the slab. The mesh size of the electrode mesh was 2mm × 3mm. The spacing between the electrodes was 260mm, and the distance from the two edges was 20mm. The distance from the upper and lower edges was 10mm. A 60V voltage was used for pre-voltage and the main voltage application.

[0031] The test results show (as shown in Table 1) that the low-content stainless steel microfilament conductive asphalt concrete specimens exhibit excellent ice melting performance at 60V voltage and -10℃ windless environment. They can melt 4mm ice in the electrode area within 160 minutes, with an energy utilization rate of up to 84.26% and a power density of approximately 415.22W / m 2 .

[0032] Example 4

[0033] This embodiment adopts a method of first mixing stainless steel microwires with asphalt and mineral powder, and then adding low-dosage stainless steel microwires with micron-level diameter, stainless matrix, high aspect ratio, high flexibility, high electrical conductivity and high mechanical properties, and adopts a pre-voltage method designed based on the conductive mechanism and a three-piece electrode layout method to give and improve the electrical conductivity of asphalt concrete, and then develops an electric heating snow-melting road surface based on its excellent electrothermal conversion characteristics. It is suitable for use in airport runways, parking lots, bridge panels, tunnel entrances and other sections with heavy snow accumulation in the form of full-size pavements, strip pavements and overlays of conductive asphalt concrete.

[0034] In this embodiment, fine-grained AC-13 type asphalt concrete is used as the matrix; the diameter of the stainless steel microwire used is 20 μm, the length is 10 mm, and the admixture amount is 0.75 vol% of the asphalt volume (equivalent to 0.27% of the mass of the asphalt concrete, i.e. 0.27 wt%); the mixing process is as follows: the aggregate is preheated at 163°C for 2 hours, the stainless steel microwire, asphalt and mineral powder are preheated at 155°C for 2 hours, and then the stainless steel microwire, asphalt and mineral powder are mixed at 155°C. The mixture was mixed for 120 seconds, followed by the addition of aggregate and mixing for another 120 seconds. The molding temperature was 150°C, and the number of compaction cycles was 100. The newly cast road slab had a size of 300mm × 300mm × 50mm. Stainless steel mesh electrodes measuring 260mm × 30mm were embedded on the left and right sides and in the middle of the slab. The mesh size of the electrode mesh was 2mm × 3mm. The spacing between the electrodes was 260mm, and the distance from the two edges was 20mm. The distance from the upper and lower edges was 10mm. A 60V voltage was used for pre-voltage and the main voltage application.

[0035] The test results show (as shown in Table 1) that the low-content stainless steel microfilament conductive asphalt concrete specimens exhibit excellent snow melting performance under a voltage of 60V and a windless environment of -10℃. They can melt a 2cm snow layer (490g) in 63 minutes and a 4cm snow layer (about 980g) in 95 minutes. The energy utilization rate is about 80% and the power density is about 2000W / m 2 .

[0036] Comparative Example 1

[0037] Comparative Example 2 uses 18 vol% graphite, 0.3 wt% carbon fiber and steel slag (instead of all aggregates) to design and prepare a multiphase composite conductive asphalt concrete. In this comparative example, the specimen matrix is ​​Superpave-12.5 graded asphalt concrete with a size of 300mm×300mm×50mm, and two L-shaped perforated aluminum plate electrodes are buried on both sides of the specimen. In this comparative example, the graphite particle size is 150μm, and the carbon fiber is asphalt-based chopped carbon fiber with a diameter of 10-14μm and a length of 4-7mm. The resistance of the specimen plate is about 600Ω, and the resistivity is 35Ω·m. Under the condition of 200V DC voltage power supply, the upper surface of the specimen plate can be heated by about 10°C after pressurization for 50 minutes; the snow melting test conducted in an outdoor environment (-2°C, 2-3 winds) shows that the specimen plate can melt 5cm of naturally accumulated snow (about 450g) within 120 minutes, with an energy density of 877.78W / m 2 .

[0038] Comparative Example 2

[0039] Comparative Example 2: 0.4 wt% carbon fiber (9 mm in length, 6.5 μm in diameter) and 30 wt% graphite (150 mesh) were used to prepare a cast conductive asphalt concrete for road ice and snow melting. The test showed that at 50 V and -8°C indoor conditions, the conductive asphalt concrete test plate (300 × 300 × 50 mm in size) with L-shaped electrodes on both sides had a high conductivity. 3 , resistance 336Ω, resistivity 16.8Ω·m) can be increased by 5-6°C after 90 minutes of pressurization; in the ice melting test under the same conditions, the specimen can melt 3.3mm of ice in 240 minutes, with an energy density of 82.67W / m 2 .

[0040] Comparative Example 3

[0041] Comparative Example 3 prepared a conductive asphalt concrete with a resistivity of 5.75Ω·m by adding 0.3wt% 6mm PAN-based carbon fiber and 12wt% graphite tailings (as fine aggregate) and adopting a top-bottom electrode arrangement. The specimen size was 300mm×300mm×50mm, and two copper mesh electrodes were embedded in the upper and lower planes of the specimen as positive and negative electrodes. In a temperature rise test at room temperature (18°C), after applying a 30V voltage for 60min, the specimen could be heated by about 11°C, and the energy density was 366W / m 2 In the ice melting test at 30V voltage and -20℃ environment, the specimen can melt 2mm ice layer within 2 hours.

[0042] Performance Testing

[0043] The ice-melting and snow-melting time parameters (pressurization time and pressure-off time), energy parameters, and test conditions of stainless steel microfilament conductive asphalt concrete in the ice-melting / snow-melting test are shown in Table 1. Table 1 shows that due to the differences in the size, dosage, preparation process and voltage of the stainless steel microfilament material, the ice-melting and snow-melting performance of the four groups of embodiments are slightly different, but the stainless steel microfilament conductive asphalt concrete specimens in Examples 1, 2, 3 and 4 all have extremely low conductive filler dosages and exhibit excellent conductivity and ice-melting and snow-melting performance. For example, the resistivity of the stainless steel microfilament conductive asphalt concrete specimen in Example 1 is 1.75Ω·m. It can melt a 4mm ice layer in the electrode area within 2 hours at a voltage of 60V and a windless environment of -10℃. The energy utilization rate is as high as 88.59%, and the power density is about 685.78W / m 2 The resistivity of the stainless steel microfilament conductive asphalt concrete specimen in Example 2 is about 0.6Ω·m. At a voltage of 60V and a windless environment of -10℃, it can melt a 2cm snow layer (490g) within 63min and a 4cm snow layer (about 980g) within 95min. The energy utilization rate is about 80% and the power density is about 2000W / m 2. The difference between the two lies mainly in the difference in mixing temperature and molding temperature. The addition of stainless steel microwires can greatly increase the thermal conductivity of asphalt concrete (about 30.38%), resulting in intensified heat exchange between asphalt concrete and the environment. Therefore, during the process of placing the test mold (in the roller) and the rolling process, the stainless steel microwire asphalt concrete cools down quickly, affecting the control of the molding temperature and compaction degree, and is not conducive to the bonding between asphalt and aggregate, resulting in a larger density of the specimen. Therefore, appropriately increasing the mixing temperature and molding temperature can increase the compaction degree of the specimen, thereby improving the performance of electric heating ice and snow melting.

[0044] Table 1 Electric heating snow melting effect based on low-content stainless steel microwire conductive asphalt concrete

[0045]

[0046] Note: The ice and snow melting time in the table is in the form of A+B, where A represents the voltage application time during the ice or snow melting test, and B represents the voltage disconnection time.

Claims

1. A low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting road surface, characterized in that: The low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting pavement is prepared by adding stainless steel micro-wires into asphalt concrete and applying voltage to the stainless steel micro-wire conductive asphalt concrete using a pre-voltage method and a three-piece electrode arrangement designed based on the conductive mechanism. The stainless steel microwire is made of molybdenum-chromium stainless steel, has a diameter of 10-30 μm, a length of 6-15 mm, and a content of 0.7-1% of the volume of asphalt in asphalt concrete. The three-piece electrode arrangement method is to place three stainless steel mesh electrodes on both sides and the middle of the stainless steel micro-wire conductive concrete electric heating snow-melting road surface; The pre-voltage method designed based on the conductive mechanism is to pre-apply instantaneous voltage to the left and middle electrodes, and the middle and right electrodes in turn before officially applying the set voltage to start electrothermal melting of ice and snow, then cut off the power, and then officially apply the set voltage to the left and right electrodes.

2. The low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting road surface according to claim 1 is characterized in that: The stainless steel microwires are added in a manner of first mixing the stainless steel microwires, asphalt and mineral powder, and then mixing them with aggregate.

3. The low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting road surface according to claim 2 is characterized in that: The mixing process is as follows: the aggregate preheating temperature is 160-170 ℃, and the preheating time is 1.5-2 hours; the asphalt, mineral powder and stainless steel microwire are preheated at 150-160 ℃, and the preheating time is 1.5-2 hours; then the stainless steel microwire, asphalt and mineral powder are mixed and stirred at 150-160 ℃ for 90-120 s, and then the aggregate is added, stirred at 150-160 ℃ for 90-120 s, and then formed at 140-150 ℃, and the number of compaction times is 75-100 times.

4. A low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting road surface according to claim 1 or 2, characterized in that: The matrix of the asphalt concrete used is a fine-grained asphalt mixture, an anti-skid wear layer, an ultra-thin wear layer or an asphalt surface treatment and an asphalt fine sand overlay.

5. The low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting road surface according to claim 3 is characterized in that: The matrix of the asphalt concrete used is a fine-grained asphalt mixture, an anti-skid wear layer, an ultra-thin wear layer or an asphalt surface treatment and an asphalt fine sand overlay.

6. A low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting road surface according to claim 1, 2 or 5, characterized in that: The side length of a single hole of the stainless steel mesh electrode is 2-5 mm.

7. The low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting road surface according to claim 3 is characterized in that: The side length of a single hole of the stainless steel mesh electrode is 2-5 mm.

8. The low-content stainless steel micro-wire conductive asphalt concrete electric heating snow-melting road surface according to claim 4 is characterized in that: The side length of a single hole of the stainless steel mesh electrode is 2-5 mm.

9. A low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting pavement according to any one of claims 1-3 or 5 or 7-8 is used in sections with heavy snow accumulation such as airport runways, parking lots, bridge decks, and tunnel entrances, and is applied in the form of full-size pavement, strip pavement, or overlay.

10. The low-content stainless steel microfilament conductive asphalt concrete electric heating snow-melting pavement according to claim 4 is used in airport runways, parking lots, bridge decks, and tunnel entrances where snow accumulates heavily, and is applied in the form of full-size pavement, strip pavement, and overlay.

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