SiO2 aerogel modified asphalt as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of modified asphalt preparation, and discloses SiO2 aerogel modified asphalt as well as a preparation method and application thereof.The preparation method comprises the following steps: heating an asphalt matrix to a flowing state, adding an aerogel additive at the same temperature into the asphalt matrix, and uniformly mixing the asphalt matrix with the aerogel additive to obtain SiO2 aerogel modified asphalt; wherein the adding amount of the aerogel additive is 1%-3% of the mass of the asphalt matrix; siO2 aerogel powder or coupled SiO2 aerogel powder is adopted as the aerogel additive. The modified asphalt prepared by the invention has good thermal insulation and heat resistance, the high-temperature performance, the anti-aging performance and the water stability are all improved, and the low-temperature performance is slightly reduced. The asphalt is endowed with thermal insulation and heat resistance, the rutting problem in a high-temperature region and the low-temperature cracking problem in a cold region can be effectively relieved, and the asphalt is simple and convenient to prepare, simple in production equipment, mild in process condition and relatively high in production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of modified asphalt preparation technology, specifically relating to a SiO2 aerogel modified asphalt, its preparation method, and its application. Background Technology

[0002] Asphalt is a complex polymer mixture that is easily affected by temperature. It exhibits a viscous flow state at high temperatures, a viscoelastic state at medium temperatures, and a hard and brittle elastic solid at low temperatures. Therefore, asphalt pavements are prone to rutting and deformation in the high temperatures of summer, and often experience low-temperature cracking in the cold winter.

[0003] The high-altitude and cold regions, which span tropical, subtropical, warm temperate, temperate and cold temperate zones and include plateaus, have highly variable climates. This poses a severe environmental challenge to asphalt pavements. Rutting in the south and cracking in the north have long been problems that have plagued road engineers. These issues have resulted in short pavement lifespan, poor service performance, and repeated repairs, leading to serious economic losses and road traffic safety problems.

[0004] Currently, the development of heat-insulating asphalt pavement materials is considered an effective way to address the impact of temperature on asphalt pavements. Related research shows that within the pavement temperature range of 40℃ to 70℃, for every 5℃ increase, rutting deformation more than doubles. The preparation of heat-insulating asphalt pavement materials can be approached from two aspects: aggregates and asphalt. Aggregates are often replaced with heat-insulating aggregates with high porosity, such as ceramics, ceramsite, ceramsite sand, refractory crushed stone, calcined bauxite, and expanded vermiculite. This easily leads to poor mechanical and fatigue properties of the asphalt pavement. While diatomaceous earth, hollow glass microspheres, and hollow polyester fibers can improve the heat-insulating properties of asphalt, these inorganic materials have poor compatibility with organic asphalt, often resulting in heat-insulating asphalt pavement materials with poor low-temperature performance and insufficient water stability, and their thermal conductivity ranges from 0.04 to 0.20 W / (m·K). Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a SiO2 aerogel modified asphalt, its preparation method, and its application. The SiO2 aerogel modified asphalt of the present invention has good high-temperature performance, low-temperature performance, and water stability, as well as good thermal insulation properties.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing SiO2 aerogel-modified asphalt includes the following steps: The asphalt matrix is ​​heated to a fluid state, and then an aerogel additive at the same temperature is added to the asphalt matrix. The asphalt matrix and the aerogel additive are then mixed to obtain SiO2 aerogel modified asphalt. The aerogel additive is added at a rate of 1%-3% of the mass of the asphalt matrix; the aerogel additive is SiO2 aerogel powder or coupled SiO2 aerogel powder.

[0007] Preferably, when the aerogel additive is SiO2 aerogel powder, the amount of SiO2 aerogel powder added is 1%-2% of the mass of the asphalt matrix; When the aerogel additive is coupled SiO2 aerogel powder, the amount of coupled SiO2 aerogel powder added is 2%-3% of the mass of the asphalt matrix.

[0008] Preferably, when adding aerogel additives at the same temperature to the asphalt matrix, the aerogel additives are added in batches, and the amount added in each batch does not exceed 1% of the mass of the asphalt matrix.

[0009] Preferably, the preparation process of the coupled SiO2 aerogel powder includes: SiO2 aerogel powder is added to a coupling agent solution, mixed evenly and dried to remove the solvent, thus obtaining coupled SiO2 aerogel powder. The mass ratio of the SiO2 aerogel powder to the coupling agent solution is in the range of 1:(1-3).

[0010] Preferably, the coupling agent solution comprises a coupling agent, water, and anhydrous ethanol, wherein the mass ratio of anhydrous ethanol to water ranges from (0 to 7):1, and the mass ratio of the total mass of anhydrous ethanol to water to the mass of the coupling agent ranges from (1 to 4):1.

[0011] Preferably, the coupling agent is one or two of the following: silane coupling agent, titanate coupling agent, aluminate coupling agent, zirconate coupling agent, and chromium complex coupling agent.

[0012] Preferably, the asphalt matrix is ​​any one of 90# base asphalt, 70# base asphalt, SBS modified asphalt, rubber asphalt, and high modulus asphalt; When the asphalt matrix is ​​heated to a fluid state: The heating temperature for 90# base asphalt is 150℃~160℃; The heating temperature for 70# base asphalt is 155℃~165℃; The heating temperature for SBS modified bitumen is 165℃~175℃; The heating temperature for rubber asphalt and high-modulus asphalt is 175℃~185℃.

[0013] Preferably, a variable speed mixing method is used to mix the asphalt matrix and the aerogel additive evenly. The variable speed mixing rate range is 500~1500 r / min, and the variable speed is 20~50 r / s.

[0014] The present invention also provides a SiO2 aerogel modified asphalt, which is prepared by the preparation method of the present invention as described above.

[0015] The present invention also provides the application of the SiO2 aerogel modified bitumen as described above, wherein the SiO2 aerogel modified bitumen is used to prepare the heat-insulating bitumen mixture.

[0016] The present invention has the following beneficial effects: In the SiO2 aerogel-modified asphalt preparation method of this invention, the asphalt matrix is ​​heated to a fluid state, and then an aerogel additive at the same temperature is added to the asphalt matrix. This avoids interface defects caused by temperature differences between the two materials, allowing the aerogel additive to be better dispersed in the asphalt matrix. This prevents the aerogel from agglomerating when the asphalt cools and avoids structural damage from high-temperature impacts, ensuring uniform distribution of the aerogel in the asphalt and allowing the low thermal conductivity of SiO2 aerogel to be stably utilized, thus ensuring a consistent distribution of the thermal conductivity of the modified asphalt. Simultaneously, the 1%-3% aerogel dosage design achieves an optimal balance between performance and cost. This range allows the aerogel to form a continuous thermally insulating network in the asphalt, avoiding weak thermal insulation due to insufficient dosage, while preventing damage to the asphalt bonding structure due to excessive dosage. Furthermore, the low dosage significantly reduces the amount of expensive SiO2 aerogel used, saving costs. Regarding additive types, SiO2 aerogel powder or coupled SiO2 aerogel powder is specifically selected, effectively addressing the compatibility issue between inorganic materials and organic asphalt. Ordinary SiO2 aerogel powder ensures basic compatibility through chemical stability, while coupled-modified powder enhances adhesion through interface optimization. Both options retain cost advantages while providing high-performance solutions to suit different engineering needs. The entire process of this invention requires only three steps: heating, adding at the same temperature, and mixing. It eliminates the need for specialized equipment and complex procedures, reducing production requirements, adapting to both factory and on-site production, shortening the modification cycle, reducing operational errors, and avoiding secondary impacts of complex processes on the performance of both aerogel and asphalt. The SiO2 aerogel-modified asphalt prepared by this invention exhibits uniform dispersion, stable performance, controllable cost, and simple operation, providing an efficient and feasible solution for the application of SiO2 aerogel in asphalt modification. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the steps required in the preparation process are briefly described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a flowchart illustrating the preparation method of a preferred embodiment of the present invention.

[0018] Figure 2(a) is a photograph of the rut plate to be tested with the heat sensor attached in Embodiment 4 of the present invention; Figure 2(b) is a photograph of the temperature test status of the top and bottom surfaces of the outdoor test rut plate in Embodiment 4 of the present invention.

[0019] Figure 3(a) is a photograph of the cut Marshall specimen in Example 5 of the present invention; Figure 3(b) is a diagram of the process of testing the thermal conductivity of the Marshall specimen in Example 5 of the present invention.

[0020] Figure 4(a) is a diagram showing the dispersion of SiO2 aerogel in asphalt in Example 3 of the present invention; Figure 4(b) is a diagram showing the dispersion of SiO2 aerogel in asphalt in Comparative Example 1 of the present invention. Detailed Implementation

[0021] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0022] This invention discloses a SiO2 aerogel-modified asphalt and its preparation method. Those skilled in the art can draw upon this content and make modifications or appropriate alterations and combinations to the methods and process parameters described herein without departing from the scope, spirit, and intent of this invention. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within this invention.

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0024] The raw material information used in the specific embodiments of this invention is as follows: Silane coupling agent KH-550, supplier: Nanjing Chuangshi Chemical Additives Co., Ltd.; 50 SiO2 aerogel powder with specific particle size, supplier: Shenzhen Zhongning Technology Co., Ltd. IC type SBS modified bitumen, supplier: Shandong Jingbo Petrochemical Co., Ltd.; Anhydrous ethanol, supplier: Shandong Ruigang Chemical Co., Ltd. Distilled water (hereinafter referred to as water), prepared in the laboratory; Coarse and fine limestone crushed stone, supplier: Ankang Tianlong Mining Engineering Construction Co., Ltd., Shaanxi Province; Recycled RAP material, supplier: Shaanxi Sanqin Road & Bridge Co., Ltd.

[0025] This invention explores a simple method and process for treating SiO2 aerogel and incorporating it into asphalt in an economical and reasonable manner to prepare SiO2 aerogel heat-insulating asphalt with excellent thermal insulation properties. Simultaneously, a novel method and process are used to treat SiO2 aerogel to enhance its adhesion to asphalt. This can simultaneously alleviate the problem of rutting deformation of asphalt pavements at high temperatures by improving both thermal insulation and asphalt mixture performance. In winter, it can also provide thermal insulation for the middle and lower layers of asphalt pavements, reducing low-temperature cracking. Furthermore, it avoids the problems of porous aggregates significantly reducing pavement performance and the poor thermal insulation effect of conventional heat-insulating materials modified asphalt. This invention has significant engineering, economic, and environmental implications.

[0026] The SiO2 aerogel modified asphalt of the present invention belongs to a type of modified asphalt, the raw materials of which include asphalt matrix, SiO2 aerogel powder, coupling agent, distilled water and anhydrous ethanol. The asphalt matrix can be any one of the following road petroleum asphalts: 90# base asphalt, 70# base asphalt, rubber asphalt, SBS modified asphalt, high modulus asphalt, etc. The SiO2 aerogel powder is a micron- or nano-sized white / light blue solid lightweight powder produced by atmospheric pressure drying or supercritical drying processes. The coupling agent is one or two of the following: silane coupling agent, titanate coupling agent, aluminate coupling agent, zirconate coupling agent, and chromium complex coupling agent. The inventors of this application have creatively discovered that adding untreated SiO2 aerogel powder to asphalt can give asphalt thermal insulation properties and improve its high-temperature performance, but it has an adverse effect on the water stability and low-temperature performance of asphalt. However, asphalt modified with SiO2 aerogel treated with coupling agent (i.e., coupled SiO2 aerogel) not only does not affect the thermal insulation properties of asphalt, but also significantly improves the adhesion of asphalt, enhances the water stability of asphalt, and improves the low-temperature performance of asphalt. This invention innovatively proposes a process for treating SiO2 aerogel powder using a coupling agent solution. First, the prepared coupling agent solution is placed in a stainless steel cup. Then, an appropriate amount of SiO2 aerogel powder is added to the coupling agent solution in batches. Each addition can be stirred evenly using an asphalt mixer or a glass rod until the SiO2 aerogel powder is completely added. Subsequently, the resulting mixture is heated in an oven and stirred once every certain period of time until the solvent is dried, thus obtaining a coupled SiO2 aerogel powder that can bond well with asphalt. Preferably, the steps for preparing the coupling agent solution include: mixing a certain mass of water with an appropriate amount of anhydrous ethanol solution, stirring with a glass rod for 1-2 minutes at a stirring speed of 50-100 r / min to obtain an alcohol solution; mixing a certain mass of the alcohol solution with an appropriate amount of coupling agent, stirring with a glass rod for 3-5 minutes at a stirring speed of 50-100 r / min to obtain the coupling agent solution.

[0027] Preferably, the coupling agent solution comprises a coupling agent, water, and anhydrous ethanol. The mass ratio of the coupling agent to the ethanol solution in the coupling agent solution is preferably 1:(1-4), while the mass ratio of anhydrous ethanol to water in the ethanol solution is preferably (0~7):1. Preferably, the mass ratio of SiO2 aerogel to coupling agent solution is 1:(1-3). Preferably, when treating SiO2 aerogel powder with coupling agent solution, the rotation speed of the asphalt mixer should be 100~300 r / min and the stirring time should be 2~5 min; the stirring speed of the glass rod should be 50~100 r / min and the stirring time should be 5~10 min. Preferably, when heating the mixture of SiO2 aerogel powder and coupling agent solution in an oven, the temperature range inside the oven should be 100℃~120℃. The mixture should be taken out of the oven every 5min~10min and stirred for 1min~3min at a speed of 50~100r / min using a stainless steel or glass rod stirrer, with a stirring interval of 10min. This invention innovatively incorporates different amounts of SiO2 aerogel powder or coupled SiO2 aerogel powder into an asphalt matrix and tests its penetration, softening point, ductility, adhesion grade, surface energy, thermal conductivity, and thermal insulation coefficient. In some embodiments of this invention, the mass fraction of untreated SiO2 aerogel added to asphalt is preferably 1% to 2%, and the mass fraction of coupled SiO2 aerogel added to asphalt is preferably 2% to 3%. This invention also innovatively compared the differences in thermal conductivity and microstructure between SiO2 aerogel-modified asphalt prepared by high-speed shearing (5000 r / min) and low-speed stirring (500~1500 r / min). It was found that the difference in thermal conductivity between the two methods was very small. The SiO2 aerogel in the SiO2 aerogel-modified asphalt prepared by high-speed shearing was more dispersed, but the SiO2 aerogel particles were severely broken, with the ratio of the number of clusters to single particles being 1:3. In contrast, the ratio of the number of clusters to single particles in the SiO2 aerogel prepared by low-speed stirring was about 1:1, but the integrity was higher. Given the small difference in thermal resistance properties between the two methods, the high requirements for high-speed shearing equipment, and the complexity of operation, the low-speed stirring method was ultimately recommended. This invention also innovatively provides a low-speed stirring preparation process for SiO2 aerogel modified asphalt, which mainly includes the following steps: First, place the barrelled asphalt matrix in an oven and heat it to a fluid state. Then, pour an appropriate amount of the asphalt matrix into a stainless steel cup and continue to place it in the oven for heat preservation. Next, weigh an appropriate amount of SiO2 aerogel powder or coupled SiO2 aerogel powder according to the mass ratio and place it in a stainless steel cup. Place it in an oven and heat it to the same temperature as the asphalt matrix. Then, take out the asphalt matrix and use a mixer to stir at variable speed. At the same time, take out the SiO2 aerogel powder or coupled SiO2 aerogel powder and add it to the asphalt matrix in batches. Stir until the asphalt matrix and SiO2 aerogel powder are uniformly mixed, or the asphalt matrix and coupled SiO2 aerogel powder are uniformly mixed, to obtain SiO2 aerogel modified asphalt. Preferably, the appropriate heating temperature to a fluid state is selected for different types of asphalt: 150℃~160℃ for 90# base asphalt, 155℃~165℃ for 70# base asphalt, 165℃~175℃ for SBS modified asphalt, and 175℃~185℃ for rubber asphalt and high modulus asphalt.

[0028] Preferably, the heating time for SiO2 aerogel powder and coupled SiO2 aerogel powder should be 10 min to 20 min. When the dosage exceeds 1%, it should be added in batches (when adding in batches, the dosage each time should not exceed 1% of the mass of the asphalt matrix), and each addition should be stirred for 5 min to 10 min. The stirring method of the mixer should be variable speed stirring, with a stirring speed of 500 to 1500 r / min and a variable speed of 20 to 50 r / s. The stirring process should be covered to ensure that the stirring process is close to a sealed state, reduce the overflow of SiO2 aerogel, and reduce the impact on the environment.

[0029] Example 1 The preparation method of SiO2 aerogel modified asphalt in this embodiment includes the following process: See Figure 1Mix 10% water and 70% anhydrous ethanol, and stir with a glass rod at 60 rpm for 2 minutes to ensure thorough mixing and prepare an alcohol solution; then add 20... % silane coupling agent KH-550 was mixed into an alcohol solution and stirred with a glass rod at a speed of 50~100 r / min for 3 min to prepare a coupling agent solution. The prepared coupling agent solution was placed in a stainless steel cup, and SiO2 aerogel powder was added to the coupling agent solution in 5 batches, with 10% SiO2 aerogel powder added in each batch, and the total amount added was 50% of the mass of the coupling agent solution. Each time SiO2 aerogel powder was added, it was stirred at a speed of 200 r / min for 3 min using an asphalt mixer until the SiO2 aerogel powder was completely added and stirred evenly. Then the mixture of SiO2 aerogel powder and coupling agent solution was placed in an oven at 105℃ and heated. Every 10 min, it was taken out of the oven and stirred with a glass rod at a speed of 60 r / min for 2 min until the solvent was dried to obtain coupled SiO2 aerogel powder. Take a small bucket of SBS modified asphalt, a stainless steel cup, and coupled SiO2 aerogel powder and place them in a 175℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of SBS modified asphalt into a stainless steel cup and place it in a 175℃ oil bath. Insert the stirring rod of the asphalt mixer into the asphalt, ensuring that the stirring blades are in the middle or lower part of the asphalt. Start the mixer and stir at a variable speed within the range of 500~1500 r / min, with the speed variation rate preferably being 50 r / s. Add 0.5% of the coupled SiO2 aerogel powder by weight of the asphalt in 4 equal portions. After each addition of coupled SiO2 aerogel powder, stir for 5 minutes to prepare SiO2 aerogel modified asphalt.

[0030] Example 2 The preparation method of SiO2 aerogel modified asphalt in this embodiment includes the following process: Mix 80% water with 20% silane coupling agent KH-550 and stir with a glass rod at 60 r / min for 3 min to prepare a coupling agent solution. Place the prepared coupling agent solution into a stainless steel cup, and then add 50% of the mass of SiO2 aerogel powder to the coupling agent solution in 5 equal batches. Each time, stir with an asphalt mixer at 200 r / min for 3 min until the SiO2 aerogel powder is completely added and stirred evenly. Then, place the mixture of SiO2 aerogel powder and coupling agent solution in an oven at 105℃ and heat it. Every 10 min, take it out of the oven and stir with a glass rod at 60 r / min for 2 min until the solvent is dried to obtain coupled SiO2 aerogel powder. Take a small bucket of SBS modified asphalt, a stainless steel cup, and coupled SiO2 aerogel powder and place them in a 175℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of SBS modified asphalt into a stainless steel cup and place it in a 175℃ oil bath. Insert the stirring rod of the asphalt mixer into the asphalt, ensuring that the stirring blades are in the middle or lower part of the asphalt. Start the mixer and stir at a variable speed within the range of 500~1500 r / min, with the speed variation rate preferably being 50 r / s. Add 0.5% of the coupled SiO2 aerogel powder by weight of the asphalt in 4 equal portions. After each addition of coupled SiO2 aerogel powder, stir for 5 minutes to prepare SiO2 aerogel modified asphalt.

[0031] Example 3 The preparation method of SiO2 aerogel modified asphalt in this embodiment includes the following process: Take a small bucket of SBS modified asphalt, a stainless steel cup, and SiO2 aerogel powder and place them in a 175℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of SBS modified asphalt into a stainless steel cup and place it in a 175℃ oil bath. Insert the stirring rod of the asphalt mixer into the asphalt, ensuring that the stirring blades are in the middle or lower part of the asphalt. Start the mixer and stir at a variable speed within the range of 500~1500 r / min, with the speed variation rate preferably being 50 r / s. Add 0.5% of the asphalt mass of SiO2 aerogel powder in 4 equal portions. After each addition of SiO2 aerogel powder, stir for 5 minutes to prepare SiO2 aerogel modified asphalt.

[0032] Example 4 The preparation method of SiO2 aerogel modified asphalt in this embodiment includes the following process: Based on the method and process of Example 1, the SiO2 aerogel modified asphalt was prepared. The SMA-13 ​​aggregate gradation curve was designed using coarse and fine limestone aggregates and RAP material with 30% aggregate mass. According to the Marshall volume design method and Marshall specimen preparation method in standard JTG F40-2004 and standard JTGE20-2011, the SiO2 aerogel modified asphalt content of 4.52% by mass was determined. Eight rut plate specimens with a size of 30cm×30cm×5cm were prepared by wheel rolling method and marked as MR-30.

[0033] Four rut slabs were taken, and temperature sensors were attached to different positions on the top and bottom surfaces of each rut slab specimen. The edges and bottom were then wrapped with 5cm thick insulating foam board. At 13:00 on a sunny summer day with an ambient temperature of 35℃, the rut slab specimens were placed outdoors in sunlight to test their heat insulation capabilities. Following the rutting test method in JTG E20-2011, the high-temperature stability of the two types of rut slab specimens was tested, comparing the differences in dynamic stability and rut depth. The attachment methods of the thermal sensors on the bottom and sides of the tested rut slabs and the outdoor test conditions are shown in Figures 2(a) and 2(b).

[0034] Example 5 The preparation method of SiO2 aerogel modified asphalt in this embodiment includes the following process: The SiO2 aerogel-modified asphalt prepared according to the method and process of Example 1 was used with the same SMA-13 ​​aggregate gradation curve and 4.52% SiO2 aerogel-modified asphalt content as in Example 4. Two sets of Marshall specimens were prepared according to the method in specification JTG E20-2011, with each set containing 3 Marshall specimens. One set of Marshall specimens was cut into specimens with a thickness of 20 mm and 40 mm, and thermal conductivity was tested together with the original 63.5 mm thick Marshall specimen. The testing instrument was a DRP-II type thermal conductivity meter, and the testing method was based on the steady-state method. The cut Marshall specimens are shown in Figure 3(a), and the testing instrument is shown in Figure 3(b).

[0035] Example 6 The preparation method of SiO2 aerogel modified asphalt in this embodiment includes the following process: The coupling SiO2 aerogel powder prepared using the method and process in Example 1 was placed in a 165℃ oven with a small bucket of 70# base asphalt, a stainless steel cup, and the coupling SiO2 aerogel powder. The heating process was as follows: A certain mass of SBS modified asphalt was poured into a stainless steel cup and placed in a 165℃ oil bath. The stirring rod of the asphalt mixer was inserted into the asphalt, ensuring that the stirring blades were in the middle or lower part of the asphalt. The mixer was started and stirred at a variable speed within the range of 500~1500 r / min, with the variable speed preferably being 50 r / s. 0.5% of the mass of coupling SiO2 aerogel powder was added to the asphalt in four equal portions. After each addition of coupling SiO2 aerogel powder, the mixture was stirred for 5 minutes to prepare the SiO2 aerogel modified base asphalt.

[0036] Example 7 The preparation method of SiO2 aerogel modified asphalt in this embodiment includes the following process: The coupled SiO2 aerogel powder prepared using the method and process in Example 1 was placed in a 175℃ oven with a small bucket of high-modulus asphalt (HMB), a stainless steel cup, and the coupled SiO2 aerogel powder. The heating process was as follows: A certain mass of SBS modified asphalt was poured into a stainless steel cup and placed in a 175℃ oil bath. The stirring rod of the asphalt mixer was inserted into the asphalt, ensuring that the stirring blades were in the middle or lower part of the asphalt. The mixer was started and stirred at a variable speed within the range of 500~1500 r / min, with the speed variation preferably being 50 r / s. 0.5% of the mass of the coupled SiO2 aerogel powder was added in four equal portions. After each addition of the coupled SiO2 aerogel powder, the mixture was stirred for 5 minutes to prepare the SiO2 aerogel modified matrix asphalt.

[0037] Comparative Example 1 The preparation method for this comparison includes the following steps: Take a small bucket of SBS modified asphalt, a stainless steel cup, and SiO2 aerogel powder and place them in a 175℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of SBS modified asphalt into a stainless steel cup and place it in a 175℃ oil bath. Insert the mixing head of the asphalt shearing machine into the asphalt, ensuring that the mixing head is in the middle or lower part of the asphalt. Start the shearing machine and shear at a shearing rate of 5000 r / min. Add 0.5% of the asphalt mass of SiO2 aerogel powder in 4 equal portions, shearing for 30 minutes after each addition, to prepare SiO2 aerogel modified asphalt.

[0038] Comparative Example 2 The preparation method for this comparison includes the following steps: Take a small bucket of SBS modified asphalt, a stainless steel cup, and SiO2 aerogel powder and place them in a 175℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of SBS modified asphalt into a stainless steel cup and place it in a 175℃ oil bath. Insert the stirring rod of the asphalt mixer into the asphalt, ensuring that the stirring blades are in the middle or lower part of the asphalt. Start the mixer and stir at a speed range of 500~1500 r / min, with the speed variation rate preferably being 50 r / s. Add 0.5% of the asphalt mass of the coupled SiO2 aerogel powder in 8 equal portions. After each addition of the coupled SiO2 aerogel powder, stir for 5 minutes to prepare SiO2 aerogel modified asphalt.

[0039] Comparative Example 3 The preparation method for this comparison includes the following steps: Place a small bucket of SBS modified bitumen and a stainless steel cup into a 175℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of SBS modified bitumen into the stainless steel cup to obtain SBS modified bitumen that can be used for sample preparation.

[0040] Comparative Example 4 The preparation method for this comparison includes the following steps: Based on the ordinary SBS modified asphalt of Comparative Example 3, coarse and fine limestone aggregates and RAP material of 30% by mass were used to make the aggregate according to the aggregate gradation curve in Example 4. Similarly, the SBS modified asphalt content of 4.52% by mass was used, and eight rut plate specimens with a size of 30cm×30cm×5cm were prepared by wheel rolling method and marked as CAM.

[0041] Four rutting slabs were taken, and temperature sensors were attached to different positions on the top and bottom surfaces of each slab specimen. The edges and bottom were then wrapped with 5cm thick insulating foam board. At 13:00 on a sunny summer day with an ambient temperature of 35℃, the rutting slab specimens were placed outdoors in direct sunlight to test their thermal insulation capabilities. Following the rutting test method in JTG E20-2011, the high-temperature stability of the remaining four rutting slab specimens was tested, comparing their dynamic stability and rutting depth differences.

[0042] Comparative Example 5 The preparation method for this comparison includes the following steps: Based on the ordinary SBS modified asphalt of Comparative Example 3, using the same crushed stone and RAP material, SMA-13 ​​type aggregate gradation curve, and SiO2 aerogel modified asphalt content of 4.52% by mass as in Example 4, two groups of Marshall specimens were prepared according to the method in specification JTG E20-2011. Each group contained 3 Marshall specimens. One group of Marshall specimens was cut into specimens with a thickness of 20 mm and 40 mm. Together with the original Marshall specimen with a thickness of 63.5 mm, the thermal conductivity was tested. The instrument used for testing was a DRP-II type thermal conductivity meter, and the testing method was based on the steady-state method.

[0043] Comparative Example 6 The preparation method for this comparison includes the following steps: Take a small bucket of 70# base asphalt and a stainless steel cup and put them into a 165℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of 70# base asphalt into the stainless steel cup to obtain 70# base asphalt that can be used for sample preparation.

[0044] Comparative Example 7 The preparation method for this comparison includes the following steps: Take a small bucket of high modulus asphalt (HMB) and a stainless steel cup and place them in a 175℃ oven and heat for 2 hours. The specific process is as follows: Pour a certain mass of high modulus asphalt (HMB) into the stainless steel cup to obtain high modulus asphalt (HMB) that can be used for sample preparation.

[0045] Comparison of test results between the above embodiments and comparative examples: Samples were prepared using the asphalt from Example 3 and Comparative Example 1, and their thermal conductivity and microstructure were tested. The microstructures are shown in Figures 4(a) to 4(b). The thermal conductivity of the asphalt was... The test results are shown in Table 1: Table 1

[0046] As can be seen from Figures 4(a) and 4(b), although the SiO2 aerogel particles in Example 3 are not as dispersed in the asphalt matrix as in Comparative Example 1, the particles in Example 3 are rounded and have a very complete structure, while the angular SiO2 aerogel particles in Comparative Example 1 are the product of high-speed shearing and fragmentation (see the particles circled in Figure 4(b)). Meanwhile, the thermal conductivity of the SiO2 aerogel asphalt in Example 3 is 0.126 W / (m·K), only 0.004 W / (m·K) higher than that of Comparative Example 1 (approximately 3.3% of Example 3). This indicates that the thermal insulation and heat-resistant effects of the two are not significantly different. Due to the advantages of the simple process, low equipment requirements, and high production efficiency of the stirring method, it is more suitable for the preparation of SiO2 aerogel modified asphalt.

[0047] Asphalt samples were prepared using the asphalt samples from Examples 1-3 and Comparative Examples 2-3. Their thermal conductivity, penetration, softening point, ductility, viscosity at 135℃, adhesion work to aggregates, and the penetration and ductility of asphalt residue after RTFOT were tested. The test results are shown in Table 2. The specifications refer to those for ID-type SBS modified asphalt. Table 2

[0048] As shown in Table 2, the SiO2 aerogel-modified asphalt in Examples 1 to 3 all meet the specifications for ID-type SBS-modified asphalt, and the thermal conductivity is reduced by 33.3% to 59.8% compared to the SBS-modified asphalt in Comparative Example 3, indicating that the asphalt in Examples 1 to 3 all have heat insulation and heat-resistant functions. The increase in softening point, the small decrease in residual ductility, and the increase in penetration ratio reflect that the high-temperature performance and anti-aging performance of the asphalt in Examples 1 to 3 are improved. The slight decrease in ductility indicates that the low-temperature performance of the asphalt in Examples 1 to 3 is slightly reduced. The good viscosity index at 135℃ indicates that the construction performance of the asphalt in Examples 1 to 3 meets the requirements. The increased adhesion work of the SiO2 aerogel-modified asphalt in Examples 1 to 2 with added coupling agent reflects that the water stability is also improved. Although the thermal conductivity in Comparative Example 2 was reduced by 55% compared to Comparative Example 3, the low-temperature ductility of Comparative Example 2 decreased too much, and the viscosity at 135℃ could not meet the specifications. Therefore, a SiO2 aerogel content of 4% was not suitable for application. Only a SiO2 aerogel content of less than 4% could take into account both the properties of the asphalt itself and its heat insulation and heat-resistant functions.

[0049] The properties of the asphalt mixture rutting slabs in Example 4 and Comparative Example 4 are shown in Table 3. The thermal insulation performance indicators are all indicators after 2 hours of outdoor light and heat testing, at which time the top and bottom surface temperatures are basically stable and more representative. To reduce the influence of external factors, the top surface temperature, bottom surface temperature, dynamic stability, and rutting depth listed in Table 3 are the average values ​​of the corresponding indicators of the four rutting slabs.

[0050] Table 3

[0051] As shown in Table 3, the temperature difference between the top and bottom surfaces of the rutting board MR-30 in Example 4 is 5.6℃ higher than that in Comparative Example 4, indicating that SiO2 aerogel-modified asphalt can impart good thermal insulation properties to asphalt mixtures. The dynamic stability of Example 4 is about 12.4% higher than that of Comparative Example 4, while the rutting depth of Example 4 is 11.1% lower than that of Comparative Example 4, indicating that incorporating SiO2 aerogel into SBS-modified asphalt improves the high-temperature stability of SBS-modified asphalt mixtures, that is, enhances the rutting resistance of SBS-modified asphalt mixtures.

[0052] The thermal conductivity test results of the asphalt mixture in Example 5 and Comparative Example 5 are shown in Table 4. The thermal conductivity test value is the average value of 3 Marshall specimens. The test set temperature is 60℃. The steady state judgment is based on the temperature difference between the top and bottom surfaces reaching a stable state. The reference temperature is 0℃.

[0053] Table 4

[0054] As shown in Table 4, the thermal conductivity of the 20mm, 40mm, and 63.5mm Marshall specimens in Example 5 is 0.054 W / (m·K), 0.066 W / (m·K), and 0.111 W / (m·K) lower than that of the Marshall specimen in Comparative Example 5, respectively. This means that the addition of SiO2 aerogel to SBS modified asphalt can reduce the thermal conductivity of the corresponding thickness of the Marshall specimen by 11.4%, 12.6%, and 18.6%, respectively. This indicates that SiO2 aerogel can improve the thermal insulation performance of the Marshall specimen, and the thermal insulation effect increases with the increase of specimen thickness.

[0055] Asphalt samples were prepared using the asphalt samples from Examples 6-7 and Comparative Examples 6-7, and their thermal conductivity, penetration, softening point, ductility, and adhesion work with aggregates were tested. The test results are shown in Table 5.

[0056] Table 5

[0057] As shown in Table 5, the thermal conductivity of the asphalt in Examples 6 and 7 was 43.9% and 47.5% lower than that in Comparative Examples 6 and 7, respectively, indicating that the addition of 2% coupling SiO2 aerogel to 70# base asphalt and high modulus asphalt can significantly improve the thermal insulation performance of the asphalt matrix. Compared with Comparative Examples 6 and 7, the penetration of Examples 6 and 7 decreased and the softening point increased, indicating that the high-temperature performance of SiO2 aerogel-modified asphalt was improved, while the ductility decreased slightly, indicating that the low-temperature performance was slightly reduced. The increase in adhesion work indicates that the water damage resistance of SiO2 aerogel-modified asphalt was improved.

[0058] In summary, this invention provides a SiO2 aerogel-modified asphalt and its preparation method. The SiO2 aerogel-modified asphalt provided by this invention is obtained from asphalt matrix, SiO2 aerogel powder, coupling agent, distilled water, and anhydrous ethanol. The modified asphalt prepared by this invention exhibits excellent thermal insulation properties, improved high-temperature performance, anti-aging properties, and water stability, while meeting low-temperature performance requirements for road use. This invention imparts thermal insulation properties to asphalt, effectively alleviating rutting problems in high-temperature areas and low-temperature cracking problems in cold regions. The preparation is simple, the production equipment is basic, the process conditions are mild, and the production efficiency is high.

[0059] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a SiO2 aerogel modified bitumen, characterized in that, The process comprises the following steps: The asphalt base is heated to a flow state, and the aerogel additive at the same temperature is added into the asphalt base, and then the asphalt base and the aerogel additive are uniformly mixed to obtain the SiO2 aerogel modified asphalt; The addition amount of the aerogel additive is 1%-3% of the mass of the asphalt base; and the aerogel additive is SiO2 aerogel powder or coupled SiO2 aerogel powder.

2. The method for preparing SiO2 aerogel-modified asphalt according to claim 1, characterized in that, When the aerogel additive is SiO2 aerogel powder, the addition amount of the SiO2 aerogel powder is 1%-2% of the mass of the asphalt base. When the aerogel additive is coupled SiO2 aerogel powder, the addition amount of the coupled SiO2 aerogel powder is 2%-3% of the mass of the asphalt base.

3. The method for preparing SiO2 aerogel-modified asphalt according to claim 2, characterized in that, When the aerogel additive at the same temperature is added into the asphalt base, the aerogel additive is added in batches, and the addition amount of each batch is not more than 1% of the mass of the asphalt base.

4. The method for preparing SiO2 aerogel-modified asphalt according to claim 1, characterized in that, The preparation process of the coupled SiO2 aerogel powder comprises the following steps: The SiO2 aerogel powder is added into a coupling agent solution, uniformly mixed, dried, and the solvent is removed to obtain the coupled SiO2 aerogel powder. The mass ratio of the SiO2 aerogel powder and the coupling agent solution is 1:(1-3).

5. The method for preparing SiO2 aerogel-modified asphalt according to claim 4, characterized in that, The components of the coupling agent solution include a coupling agent, water and anhydrous ethanol, wherein the mass ratio of the anhydrous ethanol and the water is (0-7):1, and the mass ratio of the total mass of the anhydrous ethanol and the water and the coupling agent is (1-4):

1.

6. The method of claim 4 or 5, wherein the SiO2 aerogel modified asphalt is prepared by the steps of: The coupling agent is one or two of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zirconate coupling agent and a chromium complex coupling agent.

7. The method for preparing SiO2 aerogel-modified asphalt according to claim 1, characterized in that, The asphalt base is any one of 90# base asphalt, 70# base asphalt, SBS modified asphalt, rubber asphalt and high modulus asphalt. When the asphalt base is heated to a flow state: The heating temperature of the 90# base asphalt is 150-160℃; The heating temperature of the 70# base asphalt is 155-165℃; The heating temperature of the SBS modified asphalt is 165-175℃; The heating temperature of the rubber asphalt and the high modulus asphalt is 175-185℃.

8. The method for preparing SiO2 aerogel-modified asphalt according to claim 1, characterized in that, The variable speed stirring mode is used to uniformly mix the asphalt base and the aerogel additive, and the variable speed stirring rate is 500-1500r / min, and the variable speed rate is 20-50r / s.

9. A SiO2 aerogel modified bitumen, characterized in that, The SiO2 aerogel modified asphalt is prepared by any one of the preparation methods of claims 1-8.

10. Use of the SiO2 aerogel modified bitumen according to claim 9, characterized in that, The SiO2 aerogel modified asphalt is used to prepare the heat-resistant asphalt mixture material.

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