Preparation method of steel slag asphalt concrete capable of quickly melting ice and snow under microwave action

Abstract

The invention discloses a preparation method of steel slag asphalt concrete capable of quickly melting ice and snow under the action of microwaves, which comprises the following steps: mixing SBS (styrene butadiene styrene), decrosslinked rubber and a wave-absorbing modifier to obtain a composite modifier; the composite modifier and matrix asphalt are blended, meanwhile, a stabilizer and a compatilizer are added, shearing and stirring are conducted, and wave-absorbing modified asphalt is obtained; placing the steel slag powder in an alkali solution, stirring at the temperature of more than 100 DEG C, reacting at normal pressure for more than half an hour, and after the reaction is finished, filtering and drying a product for the first time to obtain the wave-absorbing reinforced steel slag powder; the wave-absorbing modified asphalt, the steel slag coarse and fine aggregate and the wave-absorbing reinforced steel slag powder are subjected to grading design and stirred for 120-200 s at the temperature of 185-195 DEG C, and the steel slag asphalt concrete is obtained; when microwaves act on the accumulated and frozen steel slag asphalt concrete, the steel slag aggregate, the wave-absorbing reinforced steel slag powder, the wave-absorbing reinforcing agent and the like have dielectric loss and magnetic loss on the microwaves, the asphalt concrete converts microwave electromagnetic energy into heat energy, and rapid ice and snow melting of the steel slag asphalt concrete is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of materials, and in particular relates to a method for preparing steel slag asphalt concrete capable of melting ice and removing snow under the action of microwaves. Background Art

[0002] Winter icing is a huge challenge faced by cold regions. Ice accumulation on roads and bridges in winter reduces the surface friction coefficient of roads and bridge decks, making it difficult for vehicles to drive and pedestrians to travel.

[0003] In view of the shortcomings of traditional snow and ice removal methods, researchers have focused on new snow and ice melting technologies such as frozen pavement suppression, thermal heating, energy conversion, and microwave snow and ice removal. Among them, the new thermal snow and ice melting method of microwave snow and ice removal has been favored by many scholars because it does not damage the road surface, does not pollute the environment, and has high energy efficiency in thick ice removal. However, some engineering structures have poor microwave absorption capabilities, and the design and application of microwave sensitive coatings for deicing applications are still in their infancy and have many shortcomings. Summary of the invention

[0004] Purpose of the invention: To solve the shortcomings of existing snow and ice removal methods, the present invention proposes a method for preparing steel slag asphalt concrete that can melt ice and snow under the action of microwaves, which can greatly improve the dielectric loss and magnetic loss of asphalt concrete to microwaves, convert microwave electromagnetic energy into thermal energy, and achieve rapid heating of asphalt concrete to melt ice and snow under the action of microwaves. On the premise of improving the ice and snow melting performance of the prepared asphalt material, the asphalt concrete material has good high and low temperature performance.

[0005] Technical solution: A method for preparing steel slag asphalt concrete that can melt ice and remove snow under the action of microwaves, comprising the following steps:

[0006] Step 1: SBS, de-crosslinked rubber and a wave-absorbing modifier are mixed to obtain a composite modifier with wave-absorbing performance; the composite modifier is blended with base asphalt, and a stabilizer and a compatibilizer are added at the same time, and shearing and stirring are performed to obtain a wave-absorbing modified asphalt;

[0007] Step 2: placing the steel slag powder in an alkaline solution with a pH value of 9-11, stirring at a temperature greater than 100°C, and reacting at normal pressure for more than half an hour. After the reaction is completed, the product is filtered and dried once to obtain the wave absorbing enhanced steel slag powder;

[0008] Step 3: The wave-absorbing modified asphalt, steel slag coarse and fine aggregates and wave-absorbing enhanced steel slag powder are graded and stirred at 185-195° C. for 120-200 seconds to obtain steel slag asphalt concrete.

[0009] Furthermore, the wave absorbing modifier is one or a combination of pyrolysis carbon black, polyaniline, polypyrrole, silicon nitride, graphite or recycled carbon fiber.

[0010] Furthermore, the Mooney viscosity of the de-crosslinked rubber is 10 to 40, and the sol content is 40% to 70wt%.

[0011] Furthermore, the SBS, de-crosslinked rubber and absorbing modifier are mixed in an internal mixer, and the mass ratio of the three is: 0-50:20-60:5-20; the internal mixer is stably set at 60-140° C., and the mixing time is 5-15 minutes.

[0012] Furthermore, the base asphalt is 70# base asphalt or 90# base asphalt.

[0013] Furthermore, the stabilizer is sulfur, and the compatibilizer is rubber oil or aromatic oil.

[0014] Furthermore, the mass ratio of the composite modifier, the wave absorbing modifier, the stabilizer and the compatibilizer is 100:10-25:0.5-3:1-4.

[0015] Furthermore, the mass ratios of steel slag coarse and fine aggregates, wave-absorbing and enhanced steel slag powder and wave-absorbing modified asphalt are: 83.8% to 88.3%: 2.3% to 7.9%: 4.8% to 9.8%.

[0016] Furthermore, the mass ratio of the absorbing modifier, the stabilizer and the compatibilizer is 100:10-35:1-10.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0018] (1) The method of the present invention improves the microwave absorption capacity of asphalt and the high and low temperature performance of asphalt by compounding microwave absorbing materials such as polyaniline, polypyrrole, silicon nitride, etc. with SBS and de-crosslinked rubber, and solves the problem that the absorbing asphalt prepared by magnetic metal powder or ferrite has poor wettability and high cost. The constructed microwave absorbing asphalt helps to improve the service life of asphalt mixture performance;

[0019] (2) The method of the present invention does not require the preparation of complex capsules and does not use electromagnetic heating equipment to heat to melt ice and snow, thereby solving the problems of the existing ice-melting and snow-melting capsules, such as complicated preparation process, large limitations of electromagnetic heating technology, and high cost. At the same time, the asphalt concrete utilizes steel slag solid waste from the metallurgical industry, solving the problem of handling large amounts of industrial solid waste. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be further described below in conjunction with embodiments.

[0021] Embodiment 1:

[0022] Steel slag belongs to the ferrite type of absorbing material, which can generate both high dielectric loss and hysteresis loss in the process of interacting with electromagnetic waves. In this embodiment, steel slag is added to ordinary concrete as a filler. On the one hand, it can improve the dielectric loss and microwave heat conversion efficiency of ordinary concrete. The effect of steel slag powder dosage on the dielectric properties, microwave deicing efficiency and mechanical properties of concrete is studied experimentally, providing a reference for preparing microwave deicing concrete pavement using steel slag as aggregate. On the other hand, according to the research results of the research team in the early stage on steel slag drainage asphalt pavement, the use of steel slag instead of traditional aggregate can improve the cohesion between aggregate and asphalt. Under large pore conditions, steel slag asphalt concrete does not expand, and has good application prospects. Therefore, using steel slag in asphalt concrete and developing key technologies for active ice and snow suppression of absorbing asphalt concrete are effective ways to solve the problem of road icing in winter in a scientific, effective, environmentally friendly and economical way.

[0023] Therefore, this embodiment proposes a method for preparing steel slag asphalt concrete that can melt ice and remove snow under the action of microwaves, which mainly includes the following steps:

[0024] Step 1: Mix SBS (styrene-butadiene-styrene), de-crosslinked rubber, and polypyrrole in a mass ratio of 25:40:11, and react in an internal mixer at 120°C for 8 minutes until the torque is balanced to obtain a composite modifier for asphalt. Weigh 1000g of 70# matrix asphalt in a round iron can and heat it to 160°C using an electric heating jacket to completely melt it. Set the speed of the high-speed shear disperser to 4000r / min, blend 150g of the prepared composite modifier with 1000g of 70# matrix asphalt, and add 10g of stabilizer sulfur and 12g of rubber oil at the same time, and perform shear stirring at a shear stirring temperature of 180°C for 40min to obtain a modified asphalt with wave absorbing function.

[0025] In this step, polypyrrole can be replaced by other absorbing modifiers, including but not limited to one or a combination of pyrolysis carbon black, polyaniline, polypyrrole, silicon nitride, graphite or recycled carbon fiber.

[0026] The Mooney viscosity of the de-crosslinked rubber in this step is 10-40, and the sol content is 40%-70wt%.

[0027] In the actual preparation, as long as the mass ratio of SBS, de-crosslinked rubber and absorbing modifier is: 0-50:20-60:5-20; the internal mixer is set to 60-140°C for stability, and the mixing time is 5-15 minutes. And in the actual preparation, 90# matrix asphalt can also be used. In this step, rubber oil is used as a compatibilizer, which can also be replaced by other compatibilizers, such as aromatic oil. In the actual preparation, it is necessary to meet the following requirements: the mass ratio of composite modifier, absorbing modifier, stabilizer, and compatibilizer is: 100:10-25:0.5-3:1-4, and the mass ratio of absorbing modifier, stabilizer, and compatibilizer is: 100:10-35:1-10.

[0028] Step 2: Place the steel slag powder in a reactor containing an alkaline solution of NaOH or KOH with a pH value of 9-11, stir at a temperature greater than 100°C, and react at normal pressure for more than half an hour. After the reaction is completed, the product is filtered and dried once to obtain the wave-absorbing enhanced steel slag powder.

[0029] Step 3: Using AC-13 grading, the mass percentage of each raw material is: coarse and fine aggregate accounts for 84.6%, wave-absorbing and enhanced steel slag powder accounts for 6.5%, and modified asphalt accounts for 4.8%; among them, among the coarse and fine aggregates, 9.5-16mm steel slag accounts for 38.9%, 4.75-9.5mm steel slag accounts for 30.9%, 2.36-4.75mm steel slag accounts for 5.1%, and 0-2.36mm steel slag accounts for 9.7%.

[0030] Heat the coarse and fine aggregates to 185°C, heat the modified asphalt to 180-185°C, start the mixing pot, add the coarse and fine aggregates and the wave-absorbing steel slag powder, stir for 90s at 185°C, add the modified asphalt, continue stirring for 180s, cast and shape at 170-175°C, let stand for at least 24 hours, and form a large rutting plate. In the actual preparation, it is necessary to meet the following mass ratios: 83.8%-88.3% of steel slag coarse and fine aggregates, 2.3%-7.9% of steel slag powder, and 4.8%-9.8%. In the actual preparation process, it is only necessary to mix the modified asphalt with the coarse and fine aggregates of steel slag and the wave-absorbing steel slag powder, and then heat it to 185-195°C and stir for 120-200s to obtain the asphalt mixture, and then use microwave heating to cast and shape at 170-175°C, and let stand for at least 24 hours.

[0031] Step 4: After the large rutting plate is formed and cooled to room temperature, it is placed on a special test platform. The test platform has drainage holes at the bottom and is surrounded by fences of a certain height. Use ice-making molds to make cubes of ice with a side length of about 1 to 2 cm, and evenly spread the ice on the surface of the large rutting plate. Make the ice layer reach an average thickness of about 1 to 2 cm, forming a more realistic icing scene.

[0032] Step 5: Use a microwave generator with a power of 1500 watts and a frequency of 2.45 GHz as a microwave device, and install the microwave transmitting antenna about 10 to 20 cm above the surface of the large rutting plate. Pre-buried multiple high-precision temperature sensors at different locations of the large rutting plate (center, four corners and middle of the edge of the rutting plate) to achieve real-time observation of temperature changes and ice melting.

[0033] The loss factor of asphalt concrete under microwaves increases. When microwaves act on steel slag asphalt concrete covered with snow and ice, steel slag aggregate, wave-absorbing steel slag powder, wave-absorbing enhancer, etc. have dielectric loss and magnetic loss to microwaves. Asphalt concrete converts microwave electromagnetic energy into thermal energy. Through short-term microwave heating, the asphalt concrete can be quickly and evenly heated from -10°C to 5-10°C, achieving rapid ice and snow melting of steel slag asphalt concrete.

[0034] Example 2

[0035] This embodiment proposes a method for preparing steel slag asphalt concrete that can melt ice and remove snow under the action of microwaves, which mainly includes the following steps:

[0036] Step 1: Mix SBS, de-crosslinked rubber, silicon nitride and polyaniline in a mass ratio of 50:40:10:10, and react in an internal mixer at 120°C for 8 minutes until the torque is balanced to obtain a composite modifier for asphalt. Weigh 1000g of 70# matrix asphalt in a round iron can and heat it to 160°C using an electric heating jacket to completely melt it. Set the speed of the high-speed shear disperser to 4000r / min, add 150g of the prepared composite modifier and 1000g of 70# matrix asphalt for blending, and add 15g of stabilizer sulfur and 10g of rubber oil for shear stirring. The shear stirring temperature is 160°C and the time is 60min to obtain a modified asphalt with wave absorbing function.

[0037] Step 2: Same as Example 1, prepare microwave absorbing enhanced steel slag powder.

[0038] Step 3: Using AC-13 grading, the mass percentage of each raw material is: coarse and fine aggregate accounts for 82.6% (including 9.5-16mm steel slag accounting for 36.8%, 4.75-9.5mm steel slag accounting for 31.5%, 2.36-4.75mm steel slag accounting for 5.2%, 0-2.36mm steel slag accounting for 9.1%), 6.5% of wave-absorbing and enhanced steel slag powder, and 5.0% of modified asphalt; heat the coarse and fine aggregates to 185°C, heat the modified asphalt to 180-185°C, start the stirring pot, add the coarse and fine aggregates and the wave-absorbing and enhanced steel slag powder in turn, stir at 185°C for 90s, add the modified asphalt, stir for 180s, and form a large rutting plate at 170-175°C.

[0039] Step 4: Same as in Example 1, spread the ice cubes evenly on the test platform.

[0040] Step 5: Same as in Example 1, heating is performed using a microwave device and real-time observation is performed.

[0041] Example 3

[0042] This embodiment proposes a method for preparing steel slag asphalt concrete that can melt ice and remove snow under the action of microwaves, which mainly includes the following steps:

[0043] Step 1: Mix SBS, de-crosslinked rubber, cracked carbon black and graphite in a mass ratio of 40:50:8:12, and react in an internal mixer at 120°C for 8 minutes until the torque is balanced to obtain a composite modifier for asphalt. Weigh 1000g of 70# matrix asphalt in a round iron can and heat it to 160°C using an electric heating jacket to completely melt it. Set the speed of the high-speed shear disperser to 4000r / min, add 150g of the prepared composite modifier and 1000g of 70# matrix asphalt for blending, and add 15g of stabilizer sulfur and 10g of rubber oil for shear stirring. The shear stirring temperature is 160°C and the time is 60min to obtain a modified asphalt with wave absorbing function.

[0044] Step 2: Same as Example 1, prepare microwave absorbing enhanced steel slag powder.

[0045] Step 3: Using AC-13 grading, the mass percentage of each raw material is: coarse and fine aggregate accounts for 82.6% (including 9.5-16mm steel slag accounting for 36.8%, 4.75-9.5mm steel slag accounting for 31.5%, 2.36-4.75mm steel slag accounting for 5.2%, 0-2.36mm steel slag accounting for 9.1%), 6.5% of wave-absorbing and enhanced steel slag powder, and 5.0% of modified asphalt; heat the coarse and fine aggregates to 185°C, heat the modified asphalt to 180-185°C, start the stirring pot, add the coarse and fine aggregates and the wave-absorbing and enhanced steel slag powder in turn, stir at 185°C for 90s, add the modified asphalt, stir for 180s, and form a large rutting plate at 170-175°C.

[0046] Step 4: Same as in Example 1, spread the ice cubes evenly on the test platform.

[0047] Step 5: Same as in Example 1, heating is performed using a microwave device and real-time observation is performed.

[0048] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be further described below in conjunction with comparative examples.

[0049] Comparative Example 1

[0050] The comparative example adopts the following steps to prepare asphalt concrete:

[0051] Step 1: Weigh 1000g of 70# base asphalt in a round iron can, heat it to 160℃ using an electric heating jacket to completely melt it. Set the speed of the high-speed shear disperser to 4000r / min, add 150g of SBS modifier material and 1000g of 70# base asphalt for blending, and add 10g of stabilizer sulfur and 12g of rubber oil, and perform shear stirring at a shear stirring temperature of 160℃ for 50min to obtain SBS modified asphalt.

[0052] Step 2: Using AC-13 grading, the mass percentage of each raw material is: coarse and fine aggregate accounts for 82.6% (including 9.5-16mm steel slag accounting for 36.8%, 4.75-9.5mm steel slag accounting for 31.5%, 2.36-4.75mm steel slag accounting for 5.2%, 0-2.36mm steel slag accounting for 9.1%), SBS modified asphalt accounts for 5.0%; heat the coarse and fine aggregates to 185°C, heat the SBS modified asphalt to 180-185°C, start the stirring pot, add the coarse and fine aggregates and SBS modified asphalt, stir at 185°C for 180s, and form a large rutting plate at 170-175°C.

[0053] Step 3: Same as in Example 1, spread the ice cubes evenly on the test platform.

[0054] Step 4: Same as in Example 1, heating is performed using a microwave device and real-time observation is performed.

[0055] Comparative Example 2

[0056] The comparative example adopts the following steps to prepare asphalt concrete:

[0057] Step 1: Mix SBS, de-crosslinked rubber, silicon nitride and polyaniline in a mass ratio of 50:40:10:10, and react in an internal mixer at 120°C for 8 minutes until the torque is balanced to obtain a composite modifier for asphalt. Weigh 1000g of 70# matrix asphalt in a round iron can and heat it to 160°C using an electric heating jacket to completely melt it. Set the speed of the high-speed shear disperser to 4000r / min, add 150g of the prepared composite modifier and 1000g of 70# matrix asphalt for blending, and add 15g of stabilizer sulfur and 10g of rubber oil for shear stirring. The shear stirring temperature is 160°C and the time is 60min to obtain a modified asphalt with wave absorbing function.

[0058] Step 2: Using AC-13 grading, the mass percentage of each raw material is: coarse and fine aggregate accounts for 82.6% (including 9.5-16mm steel slag accounting for 36.8%, 4.75-9.5mm steel slag accounting for 31.5%, 2.36-4.75mm steel slag accounting for 5.2%, 0-2.36mm steel slag accounting for 9.1%), modified asphalt accounts for 5.0%; heat the coarse and fine aggregates to 185°C, heat the modified asphalt to 180-185°C, start the stirring pot, add the coarse and fine aggregates and modified asphalt, stir for 180s, and form a large rutting plate at 170-175°C.

[0059] Step 3: Same as in Example 1, spread the ice cubes evenly on the test platform.

[0060] Step 4: Same as in Example 1, heating is performed using a microwave device and real-time observation is performed.

[0061] The large rutting plates prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were placed on a test platform after cooling, and ice cubes of the same mass and size were weighed and evenly laid on the rutting plates. Ice and snow melting performance tests were conducted under the action of a microwave device at the same initial temperature, and the test results are shown in Table 1.

[0062] Table 1 Performance comparison of examples and comparative examples

[0063] Time for ice layer to melt completely (min) Maximum temperature of the specimen (℃) Heating rate (℃ / s) Example 1 20.2 84.7 1.91 Example 2 19.5 85.4 2.03 Example 3 20.6 84.3 1.77 Comparative Example 1 65.3 55.6 0.17 Comparative Example 2 53.9 67.8 1.12

[0064] From Table 1, the time for the ice layer to completely melt in the three embodiments is relatively close, all about 20 minutes, which is significantly shorter than that of Comparative Examples 1 and 2; the maximum temperature of the test pieces is also relatively high, between 84 and 85.5°C; the heating rate is between 1.8 and 2.1°C / s, which is also at a relatively high level. This shows that in the present invention, different modifier components and ratios can make the prepared asphalt material show good microwave absorption and heating performance under the action of microwaves, thereby effectively promoting the melting of the ice layer.

[0065] In Comparative Example 1, the modified asphalt prepared using only SBS modifier material has a much longer time for the ice layer to completely melt than that in the example. This shows that the composite modifier can significantly improve the ability of asphalt to promote the melting of ice layers under the action of microwaves, compared with a single SBS modifier, and greatly accelerates the ice melting rate. In Comparative Example 2, only microwave-absorbing modified asphalt is used, and microwave-absorbing steel slag powder is not used. Although the performance is better than that of Comparative Example 1, there is still a large gap compared with the example, which shows that only by simultaneously modifying the asphalt and steel slag to absorb microwaves can the best effect be achieved.

[0066] The present invention prepares modified asphalt with good microwave absorption capacity by compounding absorbing materials such as polyaniline, polypyrrole, silicon nitride with SBS and de-crosslinked rubber, and shearing and blending with asphalt, and at the same time has good high and low temperature performance. On the other hand, steel slag coarse and fine aggregates and steel slag powder replace ordinary aggregates and mineral powder, which improves the loss factor of asphalt concrete under microwaves. When microwaves act on the damaged road surface of the microwave ice-melting and snow-melting asphalt concrete, both the aggregates and asphalt have dielectric loss and magnetic loss to microwaves. The asphalt concrete converts microwave electromagnetic energy into thermal energy. By heating for a certain period of time, the asphalt concrete is quickly and evenly heated to 45-85°C, and the thermal repair effect of asphalt is utilized to achieve rapid ice-melting and snow-melting of asphalt concrete.

Claims

1. A method for preparing steel slag asphalt concrete that can quickly melt ice and snow under the action of microwaves, characterized in that: The following steps are involved: Step 1: SBS, de-crosslinked rubber and microwave absorbing modifier are mixed to obtain a composite modifier with microwave absorbing performance; The composite modifier is mixed with the base asphalt, and a stabilizer and a compatibilizer are added, and shearing and stirring are performed to obtain the wave-absorbing modified asphalt; Step 2: placing the steel slag powder in an alkaline solution, stirring at a temperature greater than 100°C, and reacting at normal pressure for more than half an hour. After the reaction is completed, the product is filtered and dried once to obtain the wave absorbing enhanced steel slag powder; Step 3: The wave-absorbing modified asphalt, steel slag coarse and fine aggregates and wave-absorbing enhanced steel slag powder are graded and stirred at 185-195° C. for 120-200 seconds to obtain steel slag asphalt concrete.

2. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The wave absorbing modifier is one or a combination of pyrolysis carbon black, polyaniline, polypyrrole, silicon nitride, graphite or recycled carbon fiber.

3. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The Mooney viscosity of the de-crosslinked rubber is 10-40, and the sol content is 40%-70wt%.

4. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The SBS, de-crosslinked rubber and wave absorbing modifier are mixed in an internal mixer, and the mass ratio of the three is 0-50:20-60:5-20; the internal mixer is stably set at 60-140°C, and the mixing time is 5-15 minutes.

5. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The matrix asphalt is 70# matrix asphalt or 90# matrix asphalt.

6. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The stabilizer is sulfur, and the compatibilizer is rubber oil or aromatic oil.

7. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The pH value of the alkaline solution is 9-11.

8. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The mass ratio of the composite modifier, the wave-absorbing modifier, the stabilizer and the compatibilizer is 100:10-25:0.5-3:1-4.

9. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The mass ratios of steel slag coarse and fine aggregates, wave-absorbing and enhanced steel slag powder and wave-absorbing modified asphalt are: 83.8% to 88.3%: 2.3% to 7.9%: 4.8% to 9.8%.

10. The method for preparing steel slag asphalt concrete capable of rapidly melting ice and snow under microwave action according to claim 1, characterized in that: The mass ratio of the wave absorbing modifier, the stabilizer and the compatibilizer is 100:10-35:1-10.