A hard pitch masterbatch preparation method based on low-temperature granulation

Abstract

This invention relates to the field of road construction materials technology, and particularly to a method for preparing hard asphalt masterbatch based on low-temperature granulation. The method includes: melting de-oiled asphalt in a reactor; dynamically adjusting the stirring speed based on the molten state to obtain activated molten asphalt; adding Guangyuan rock asphalt and SBS compatibilizer to the activated molten asphalt for primary homogenization treatment; determining the dispersion uniformity characteristic value to adjust the shear speed to obtain preliminary mixed asphalt; transferring the preliminary mixed asphalt to an ultrasonic homogenizer for secondary homogenization treatment; cooling the mixed asphalt and adding a phase change material to start stirring; detecting the dispersion variation coefficient of the phase change material to adjust the stirring speed and stirring time; feeding the mixed colloid into a twin-screw granulator; controlling the barrel temperature in stages to determine the temperature difference between adjacent sections; extruding cylindrical granules; cooling to room temperature via a conveyor belt; and sealing and packaging to obtain the finished product. This invention solves the problem of low replacement rate of petroleum asphalt with de-oiled asphalt.

Description

Technical Field

[0001] This invention relates to the field of road construction materials technology, and in particular to a method for preparing hard asphalt masterbatch based on low-temperature granulation. Background Technology

[0002] In existing technologies, the highest replacement rate of petroleum asphalt with deoiled asphalt is only 15%. Furthermore, using deoiled asphalt alone results in extremely poor low-temperature crack resistance of the asphalt mixture, with a low-temperature flexural strain ≤1800με, making it unsuitable for cold-winter climates. Forcibly increasing the replacement rate to over 20% leads to problems such as low-temperature brittleness and high-temperature segregation ≥2.5%. The high rutting resistance of Guangyuan rock asphalt is not combined with the temperature adaptability of phase change materials; relying solely on deoiled asphalt as a single base material to improve hardness fails to balance high replacement rates with high and low-temperature performance. Conventional asphalt preparation methods only employ low-speed mixing, resulting in poor compatibility between deoiled asphalt and base asphalt, with component dispersion particle sizes ≥10μm, leading to insufficient stability in road performance. Moreover, existing hard asphalt is mostly liquid, prone to stratification during transportation and storage, and suffers from poor metering accuracy during on-site mixing, making precise control of quantitative replacement impossible.

[0003] Chinese Patent Publication No. CN113621244A discloses a DOA-SBS-rubber powder ternary composite high-modulus modified asphalt and its preparation method. The modified asphalt comprises the following raw materials: No. 70 asphalt, deoiled asphalt, rubber powder, SBS modifier, and stabilizer. However, the proportion of deoiled asphalt used in this method to replace petroleum asphalt is less than 10%, and deoiled asphalt itself has high hardness and brittleness. Simply increasing its content to pursue high modulus will directly lead to a sharp decrease in the flexibility of the asphalt binder system, causing it to become brittle at low temperatures, resulting in extremely poor low-temperature crack resistance. Summary of the Invention

[0004] Therefore, the present invention provides a method for preparing hard asphalt masterbatch based on low-temperature granulation, in order to overcome the problem of low proportion of deoiled asphalt replacing petroleum asphalt in the prior art.

[0005] To achieve the above objectives, the present invention provides a method for preparing hard asphalt masterbatch based on low-temperature granulation, comprising: Step S1: Add the deoiled asphalt into the reactor, heat it to the first preset temperature, start stirring and melt it at the first stirring speed. During the melting process, the melting state is determined based on the real-time measured viscosity of the first asphalt melt, and the stirring speed is dynamically adjusted to obtain activated molten asphalt. Step S2: Determine the amount of 70# road petroleum asphalt to be added based on the penetration of the activated molten asphalt. After adding the asphalt, heat it to the second preset temperature to obtain the asphalt mixture raw material. Step S3: Based on the difference between the viscosity of the asphalt mixture and the viscosity of the first asphalt melt in step S1, determine the amount of SBS compatibilizer to be added, start the high-speed shear homogenizer to perform primary homogenization treatment with a preset shear speed and shear gap, and obtain preliminary mixed asphalt. Step S4: Transfer the preliminary mixed asphalt to an ultrasonic homogenizing device. Determine the initial power and frequency of the ultrasonic homogenizing device based on the difference between the particle size of Guangyuan rock asphalt in the preliminary mixed asphalt and the preset target particle size, and perform secondary homogenization treatment to obtain mixed asphalt. Step S5: When the particle size of the mixed asphalt reaches the preset target range, a rapid sample is taken and the microstructure of the sample is scanned to confirm that the SBS phase is in a continuous network shape, the rock asphalt particles are fully wrapped by the asphalt phase and there are no large-sized agglomerates. Step S6: After cooling the mixed asphalt to the third preset temperature, add the phase change material, start the paddle mixer and adjust the mixing speed to the second mixing speed. Adjust the mixing speed and mixing time based on the detected dispersion variation coefficient to obtain the mixed colloid. Step S7: The mixed colloid is fed into a twin-screw granulator, the barrel temperature is controlled in stages, and the temperature difference between adjacent sections is determined based on the dispersion variation coefficient, and cylindrical granules are extruded. Step S8: The cylindrical particles are cooled to room temperature by an air-cooled conveyor belt, sealed and packaged to obtain the finished hard asphalt masterbatch.

[0006] Further, step S1 includes: Step S11: Add the deoiled bitumen into the reactor and heat it to 150°C; Step S12: Start the anchor stirring and stir at 300 r / min for 30 min to melt; Step S13: Based on the result that the real-time measured asphalt melt viscosity is less than the preset viscosity threshold, it is determined that the deoiled asphalt has been activated. Based on the result that the real-time measured asphalt melt viscosity is greater than or equal to the preset viscosity threshold, it is determined that step S12 is repeated and the stirring speed is increased by 50 r / min.

[0007] Further, determining the amount of 70# road petroleum asphalt to be added in step S2 includes: Step S21: Obtain the measured penetration of the activated molten asphalt; Step S22: Calculate the first needle penetration difference value based on the difference between the measured needle penetration and the target needle penetration. Step S23: Calculate the second penetration difference value based on the difference between the measured penetration and the penetration of 70# road petroleum asphalt; Step S24: Calculate the blending ratio coefficient based on the ratio of the difference between the first needle penetration and the second needle penetration. Step S25: Calculate the amount of 70# road petroleum asphalt to be added based on the product of the activated molten asphalt mass and the blending ratio coefficient.

[0008] Further, determining the amount of SBS compatibilizer added in step S3 includes: Step S31: Obtain the viscosity of the asphalt mixture raw material; Step S32: Calculate the viscosity difference value based on the difference between the viscosity of the asphalt mixture and the viscosity of the first asphalt melt. Step S33: Calculate the amount of SBS compatibilizer added based on the product of the viscosity difference value and the basic amount of compatibilizer added.

[0009] Further, step S4 includes: Step S41: Maintain the system temperature at 165℃~170℃ and transfer it to an ultrasonic homogenization device; Step S42: Perform ultrasonic homogenization at 500W power and 20kHz frequency for 12 minutes; Step S43: During the processing, samples are taken every 3 minutes to detect the maximum particle size of the mixture; Step S44: Based on the result that the maximum particle size is greater than 10 μm, extend the ultrasonic treatment for 3 min and repeat step S43 until the maximum particle size is no greater than 10 μm.

[0010] Further, step S5 includes: Step S51: Sampling is performed when the particle size D90 of Guangyuan rock asphalt is detected to be less than or equal to 5 μm and continuously and stably greater than or equal to 3 minutes. Step S52: Obtain a microscopic image of the sample under 400x magnification and scan the microscopic image. If the area percentage of the SBS phase is greater than or equal to 30% and there are no asphalt aggregates greater than or equal to 20μm, the homogenization treatment is deemed qualified. If the area percentage of the SBS phase is less than 30% and there are asphalt aggregates greater than or equal to 20μm, repeat step S4.

[0011] Further, in step S6, obtaining the dispersion coefficient of variation includes: Step S61: Detect the particle size distribution of the phase change material; Step S62: Calculate the standard deviation of the particle size and the average particle size of the phase change material; Step S63: Calculate the standard deviation of particle size and the average particle size to obtain the dispersion variation coefficient.

[0012] Further, in step S6, based on the result that the dispersion variation coefficient is less than or equal to 15%, it is determined that the phase change material has been uniformly dispersed, and based on the result that the dispersion variation coefficient is greater than 15%, it is determined that the stirring time be extended by 10 minutes and the stirring speed be increased by 10%.

[0013] Further, step S7 includes: Step S71: The mixed colloid is fed into a twin-screw granulator, wherein the screw speed of the twin-screw granulator is set to 150 r / min; Step S72: The barrel temperature is divided into three segments for control. The temperature difference between adjacent segments is determined based on the product of the dispersion coefficient of variation and the base regulating temperature. The preset temperature of Zone 1 is 100℃, the basic adjustment temperature is 10℃, the temperature of Zone 1 is lower than the temperature of Zone 2, and the temperature of Zone 2 is lower than the temperature of Zone 3. Step S73: Extrude molten strips through a cylindrical template with a die head aperture of 4mm; Step S74: The strip is cut into cylindrical particles with a particle size of 3mm to 5mm by a rotating cutter.

[0014] Furthermore, the basic mass ratio of the hard asphalt masterbatch is: 40-50 parts deoiled asphalt, 20-25 parts Guangyuan rock asphalt, 5-8 parts phase change material, 15-25 parts 70# road petroleum asphalt, and 3-5 parts SBS compatibilizer. The phase change material is PEG4000 or paraffin composite phase change material, and the SBS compatibilizer is YH-792.

[0015] Compared with existing technologies, the beneficial effects of this invention are that it solves the problems of high initial viscosity and poor fluidity of deoiled asphalt through an innovative process of dynamically adjusting the stirring speed. The high initial viscosity of the deoiled asphalt is addressed by real-time monitoring of the melt viscosity; when the viscosity drops below a preset threshold, it indicates that the asphalt macromolecular chains begin to untangle, improving fluidity. This forms activated molten asphalt with higher reactivity, laying the foundation for subsequent compatibility modification and enabling the deoiled asphalt to form a well-compatible system with the base asphalt.

[0016] Furthermore, this invention calculates a first penetration difference value based on the difference between the measured penetration of activated molten asphalt and the target penetration value; then, it calculates a second penetration difference value based on the difference between the measured penetration and the penetration of 70# asphalt; and calculates the blending ratio coefficient by the ratio of the first penetration to the second penetration difference value, ensuring precise control of the penetration of the mixed system. This achieves precise control of asphalt mixture performance under high-proportion replacement of deoiled asphalt, avoiding the performance degradation caused by increased replacement rate in traditional methods.

[0017] Furthermore, this invention quantifies the change in polarity / polarization of the system by measuring the viscosity difference, and then inversely calculates the amount of SBS compatibilizer added. The difference between the viscosity of the asphalt mixture and the original melt viscosity reflects the degree of system compatibility. A larger viscosity difference indicates poorer compatibility, requiring more SBS as a bridge to enhance interfacial bonding and form a continuous three-dimensional network structure. Precise control of the SBS compatibilizer addition amount enables the SBS phase to form a continuous network structure, significantly improving the elasticity and toughness of the asphalt. Furthermore, this invention employs an innovative process of ultrasonic homogenization and real-time particle size monitoring to solve the problem of uneven dispersion of rock asphalt. Guangyuan rock asphalt is treated with ultrasonic homogenization to reduce the particle size to less than or equal to 10μm. The ultrasonic treatment time is dynamically adjusted to ensure that the rock asphalt particles are fully coated by the asphalt phase, forming a uniform dispersion system and giving full play to the high rutting resistance of Guangyuan rock asphalt.

[0018] Furthermore, this invention introduces the dispersion variation coefficient as a control index to solve the problem of uneven dispersion of phase change materials. By calculating the ratio of the standard deviation of the particle size of the phase change material to the average particle size, the dispersion uniformity is quantified to ensure that the phase change material is uniformly dispersed in asphalt and to achieve temperature-adaptive regulation.

[0019] Furthermore, this invention innovatively transforms liquid asphalt into granular masterbatch, solving transportation and storage problems. By using a twin-screw granulator for segmented temperature control, the temperature difference between adjacent zones is determined based on the dispersion coefficient of variation. This achieves the granulation of hard asphalt, avoiding stratification during transportation and storage, ensuring metering accuracy during on-site mixing, and realizing precise control of quantitative substitution. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of a method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention; Figure 2 This is a schematic diagram of step S1 in the method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention. Figure 3 This is a schematic diagram of step S4 in the method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention. Figure 4 This is a logical diagram of step S6 in the method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0022] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] Please see Figure 1 As shown, it is a schematic flowchart of a method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention, including: Step S1: Add the deoiled asphalt into the reactor, heat it to the first preset temperature, start stirring and melt it at the first stirring speed. During the melting process, the melting state is determined based on the real-time measured viscosity of the first asphalt melt, and the stirring speed is dynamically adjusted to obtain activated molten asphalt. Step S2: Determine the amount of 70# road petroleum asphalt to be added based on the penetration of the activated molten asphalt. After adding the asphalt, heat it to the second preset temperature to obtain the asphalt mixture raw material. Step S3: Based on the difference between the viscosity of the asphalt mixture and the viscosity of the first asphalt melt in step S1, determine the amount of SBS compatibilizer to be added, start the high-speed shear homogenizer to perform primary homogenization treatment with a preset shear speed and shear gap, and obtain preliminary mixed asphalt. Step S4: Transfer the preliminary mixed asphalt to an ultrasonic homogenizing device. Determine the initial power and frequency of the ultrasonic homogenizing device based on the difference between the particle size of Guangyuan rock asphalt in the preliminary mixed asphalt and the preset target particle size, and perform secondary homogenization treatment to obtain mixed asphalt. Step S5: When the particle size of the mixed asphalt reaches the preset target range, a rapid sample is taken and the microstructure of the sample is scanned to confirm that the SBS phase is in a continuous network shape, the rock asphalt particles are fully wrapped by the asphalt phase and there are no large-sized agglomerates. Step S6: After cooling the mixed asphalt to the third preset temperature, add the phase change material, start the paddle mixer and adjust the mixing speed to the second mixing speed. Adjust the mixing speed and mixing time based on the detected dispersion variation coefficient to obtain the mixed colloid. Step S7: The mixed colloid is fed into a twin-screw granulator, the barrel temperature is controlled in stages, and the temperature difference between adjacent sections is determined based on the dispersion variation coefficient, and cylindrical granules are extruded. Step S8: The cylindrical particles are cooled to room temperature by an air-cooled conveyor belt, sealed and packaged to obtain the finished hard asphalt masterbatch.

[0024] Please see Figure 2 As shown, this is a logical schematic diagram of step S1 in the method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention. Step S1 includes: Step S11: Add the deoiled bitumen into the reactor and heat it to 150°C; Step S12: Start the anchor stirring and stir at 300 r / min for 30 min to melt; Step S13: The viscosity of the asphalt melt is measured in real time by an online viscometer. Based on the result that the viscosity of the asphalt melt is less than a preset viscosity threshold, it is determined that the deoiled asphalt has been activated. Based on the result that the viscosity of the asphalt melt is greater than or equal to the preset viscosity threshold, it is determined that step S12 is repeated and the stirring speed is increased by 50 r / min. The preset viscosity threshold is 5000 mPa·s.

[0025] In step S1, the deoiled asphalt has a high initial viscosity and poor fluidity. By monitoring the melt viscosity in real time and dynamically adjusting the stirring speed, heat and mass transfer can be accelerated, local overheating and carbonization can be avoided, and the asphalt macromolecular chains can be untangled and activated to form activated molten asphalt with higher reactivity, laying the foundation for subsequent compatibility modification.

[0026] Specifically, determining the amount of 70# road petroleum asphalt to be added in step S2 includes: Step S21: Obtain the measured penetration of the activated molten asphalt; Step S22: Calculate the first needle penetration difference value based on the difference between the measured needle penetration and the process target needle penetration. Preferably, the process target needle penetration is 70 (0.1 mm). Step S23: Calculate the second penetration difference value based on the difference between the measured penetration and the penetration of 70# road petroleum asphalt; Step S24: Calculate the blending ratio coefficient based on the ratio of the difference between the first needle penetration and the second needle penetration. Step S25: Calculate the amount of 70# road petroleum asphalt to be added based on the product of the activated molten asphalt mass and the blending ratio coefficient.

[0027] It is understood that in this embodiment, a dual difference ratio model is established by combining the measured penetration of activated asphalt with the penetration of 70# asphalt and the performance of the target product, and the dosage of 70# asphalt is scientifically calculated to ensure the performance balance of the mixed system.

[0028] Specifically, determining the amount of SBS compatibilizer to be added in step S3 includes: Step S31: Obtain the viscosity of the asphalt mixture raw material; Step S32: Calculate the viscosity difference value based on the difference between the viscosity of the asphalt mixture and the viscosity of the first asphalt melt. Step S33: Calculate the amount of SBS compatibilizer added based on the product of the viscosity difference value and the basic amount of compatibilizer added. Preferably, the basic amount of SBS compatibilizer added is 5 parts.

[0029] It is understood that in this embodiment, the amount of SBS compatibilizer added directly affects the formation of the elastic network. This invention uses the viscosity difference between the mixed raw materials and the original melt as a criterion to quantify the change in the polarity / polarization degree of the system, thereby inferring the required amount of SBS. The greater the viscosity difference, the worse the compatibility, and more SBS is needed as a bridge to enhance the interfacial bonding and form a continuous three-dimensional network structure.

[0030] Please see Figure 3 As shown, this is a logical schematic diagram of step S4 in the method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention. Step S4 includes: Step S41: Maintain the system temperature at 165℃~170℃ and connect the ultrasonic homogenizer. Step S42: Perform ultrasonic homogenization at 500W power and 20kHz frequency for 12 minutes; Step S43: During the processing, samples are taken every 3 minutes, and the maximum particle size of the mixture is detected by an offline particle size analyzer; Step S44: Based on the result that the maximum particle size is greater than 10 μm, extend the ultrasonic treatment for 3 min and repeat step S33 until the maximum particle size is no greater than 10 μm.

[0031] Guangyuan rock asphalt is a natural hard asphalt that needs to be refined to fully exert its effects. Ultrasonic cavitation can generate instantaneous extreme pressure, high temperature, and strong shock waves in a liquid, producing tremendous crushing force on particle agglomerates. Ultrasonic parameters are adjusted based on the difference between the real-time detected particle size and the target particle size, forming a closed-loop control system. This ensures that regardless of fluctuations in raw material batches, sufficient ultrasonic energy input can process the rock asphalt particles to the ideal fineness.

[0032] Specifically, step S5 includes: Step S51: When the online laser particle size analyzer detects that the D90 of Guangyuan rock asphalt particles is less than or equal to 5 μm and remains stable for ≥3 minutes, sampling is performed. Step S52: Obtain a microscopic image of the sample under 400x magnification and scan the microscopic image. If the area percentage of the SBS phase is greater than or equal to 30% and there are no asphalt aggregates greater than or equal to 20μm, the homogenization treatment is deemed qualified. If the area percentage of the SBS phase is less than 30% and there are asphalt aggregates greater than or equal to 20μm, repeat step S3.

[0033] Understandably, direct observation using equipment such as scanning electron microscopy confirms that the SBS phase forms a continuous network, proving that the SBS has fully swelled, stretched, and cross-linked, forming a three-dimensional network that provides elasticity and toughness. This is the microstructure guarantee for low-temperature crack resistance. Confirmation that the rock asphalt particles are fully encapsulated by the asphalt phase and lack large-sized agglomerates demonstrates that the rock asphalt is uniformly dispersed, well-bonded to the asphalt matrix, and can stably provide rigidity reinforcement, rather than existing as a defect. If the test fails, return to step S4 for reprocessing to ensure quality.

[0034] Please see Figure 4 As shown, this is a logical diagram of step S6 in the method for preparing hard asphalt masterbatch based on low-temperature granulation according to an embodiment of the present invention. In step S5, obtaining the dispersion variation coefficient includes: Step S61: The particle size distribution of the phase change material is detected in real time using an online laser particle size analyzer; Step S62: Calculate the standard deviation of the particle size and the average particle size of the phase change material; Step S63: Calculate the standard deviation of particle size and the average particle size to obtain the dispersion variation coefficient.

[0035] Specifically, in step S6, it is determined that the phase change material has been uniformly dispersed based on the result that the dispersion variation coefficient is less than or equal to 15%, and it is determined that the stirring time is extended by 10 minutes and the stirring speed is increased by 10% based on the result that the dispersion variation coefficient is greater than 15%.

[0036] Understandably, the coefficient of variation (CV) is a statistical indicator that measures the dispersion of data. It quantifies the uniformity of dispersion by detecting particle size distribution online and calculating the CV value. A smaller CV value indicates a more concentrated and uniform particle size distribution in the phase change material. By adjusting the stirring speed and time based on CV value feedback, the dispersion process can be proactively optimized to its best state, ensuring that each phase change material particle can effectively function.

[0037] Specifically, step S7 includes: Step S71: The mixed colloid is fed into a twin-screw granulator, wherein the screw speed of the twin-screw granulator is set to 150 r / min; Step S72: The barrel temperature is divided into three segments for control. The temperature difference between adjacent segments is determined based on the product of the dispersion coefficient of variation and the base regulating temperature. The preset temperature of Zone 1 is 100℃, the basic adjustment temperature is 10℃, the temperature of Zone 1 is lower than the temperature of Zone 2, and the temperature of Zone 2 is lower than the temperature of Zone 3. Step S73: Extrude molten strips through a cylindrical template with a die head aperture of 4mm; Step S74: The strip is cut into cylindrical particles with a particle size of 3mm to 5mm by a rotating cutter.

[0038] Specifically, the basic mass ratio of the hard asphalt masterbatch is: 40-50 parts deoiled asphalt, 20-25 parts Guangyuan rock asphalt, 5-8 parts phase change material, 15-25 parts 70# road petroleum asphalt, and 3-5 parts SBS compatibilizer. The phase change material is PEG4000 or paraffin composite phase change material, and the SBS compatibilizer is YH-792.

[0039] This invention, through the synergistic formulation design of deoiled asphalt, rock asphalt, SBS and phase change materials, combined with an intelligent preparation process based on feedback from multiple parameters such as viscosity, penetration, particle size and dispersion uniformity, achieves a significant reduction in raw material costs and petroleum consumption, while simultaneously obtaining high and low temperature road performance that surpasses traditional formulations, thus realizing a dual breakthrough in both economy and technology. Example 1

[0040] In this embodiment, the basic mass ratio of the hard asphalt masterbatch is 40 parts deoiled asphalt, 20 parts Guangyuan rock asphalt, 5 parts phase change material, and 25 parts 70# asphalt. Step S1: Add 500 kg of deoiled bitumen into a reactor equipped with a temperature control and viscosity online monitoring system, heat it to the first preset temperature of 160°C, start stirring, and set the initial stirring speed to 60 rpm.

[0041] During the melting process, the viscosity of the asphalt melt is monitored in real time by an online viscometer. When the viscosity is detected to drop from the initial 8000 mPa·s to 3000 mPa·s, it is determined that the melting is becoming uniform. The stirring speed is then dynamically increased to 80 rpm, and stirring is continued for 30 minutes to obtain activated molten asphalt with good fluidity.

[0042] In step S2, the penetration of the activated molten asphalt was measured to be 70 (0.1 mm). According to the formula, 14.4 wt% of 70# road petroleum asphalt needs to be added, which is 84.5 kg.

[0043] After adding the material, the temperature is raised to the second preset temperature of 170℃, and stirred at a constant temperature for 20 minutes to obtain a uniform asphalt mixture.

[0044] In step S3, the viscosity of the asphalt mixture was measured to be 2200 mPa·s, while the viscosity of the first asphalt melt in step S1 was 3000 mPa·s, with a difference of 800 mPa·s; the amount of SBS compatibilizer added was calculated to be 0.13 wt%, which is 0.76 kg.

[0045] Start the high-speed shear homogenizer, set the shearing speed to 3000 rpm, the shearing gap to 0.3 mm, and shear for 45 minutes to obtain preliminary mixed asphalt.

[0046] Step S4: Sample analysis of the Guangyuan rock asphalt in the preliminary mixed asphalt shows that the average particle size is 45μm, the target particle size is ≤20μm, and the difference is 25μm. Based on the difference, set the initial parameters of the ultrasonic homogenizing device to 800W and 25kHz, and perform ultrasonic treatment for 20 minutes, during which the system temperature is maintained at ≤175℃ by circulating cooling.

[0047] Step S5: When the laser particle size analyzer shows that the rock asphalt particle size D90 ≤ 18 μm, a sample is quickly taken and the microstructure is observed using a field emission scanning electron microscope. The results show that the SBS phase forms a continuous three-dimensional network structure, the rock asphalt particles are uniformly dispersed and completely wrapped by the asphalt matrix, and there are no aggregates larger than 30 μm, which meets the requirements.

[0048] Step S6: Cool the mixed asphalt to the third preset temperature of 150°C, add 5wt%, i.e. 29.6kg of micro phase change material, start the paddle mixer, and set the initial second mixing speed to 70rpm. The dispersion variation coefficient was measured online, with an initial value of 18%. The stirring speed was gradually increased to 90 rpm and the stirring time was extended to 40 min until the dispersion variation coefficient was less than 8%, thus obtaining a uniformly mixed colloid.

[0049] Step S7: The mixed colloid is fed into a twin-screw granulator and the temperature is controlled in four sections: feeding section 140℃, compression section 145℃, homogenization section 150℃, and extrusion section 148℃. Based on a final dispersion variation coefficient of 7.5%, and with the interval temperature difference set to ≤5℃, cylindrical particles with a diameter of 3mm are stably extruded.

[0050] Step S8: The cylindrical particles are cooled to room temperature by an air-cooled conveyor belt at a temperature of 25°C and a speed of 2 m / s, and then sealed and packaged to obtain the hard asphalt masterbatch product. Example 2

[0051] In this embodiment, the basic mass ratio of the hard asphalt masterbatch is 50 parts deoiled asphalt, 25 parts Guangyuan rock asphalt, 8 parts phase change material, 12 parts 70# asphalt, and 5 parts SBS; the preset preparation parameters are the same as in Example 1. Example 3

[0052] In this embodiment, the basic mass ratio of the hard asphalt masterbatch is 45 parts deoiled asphalt, 23 parts Guangyuan rock asphalt, 3 parts phase change material, 20 parts 70# asphalt, and 4 parts SBS; the preset preparation parameters are the same as in Example 1. Comparative example: In this comparative example, the basic mass ratio of the hard asphalt masterbatch is 60 parts deoiled asphalt and 40 parts 70# asphalt, without the addition of Guangyuan rock asphalt, phase change material and SBS. The preparation process uses a single stirring motion at a speed of 1000 r / min, without activation, homogenization, or granulation steps. Performance tests were conducted on the products of Examples 1-3 and the comparative examples, and the results are shown in the table below: Table 1 Product Performance Test Results ; It is evident that Examples 1-3, through the synergistic effect of multiple materials and refined processes, can still comprehensively surpass the performance of traditional formulations at low substitution rates even with a high proportion of petroleum asphalt substitution, achieving both high performance and low cost.

[0053] The performance of Examples 1-3 all meet high standards and provide options for different application scenarios. For example, in regions where high-temperature rutting resistance is a priority, the formulation of Example 2 can be selected; while in regions where low-temperature performance is more critical, the formulation of Example 1 can be used as a reference.

[0054] This invention successfully solves the industry problem of large-scale modification of asphalt, especially by achieving long-term stable dispersion of the modifier in asphalt, thus giving it value for engineering applications.

[0055] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing hard asphalt masterbatch based on low-temperature granulation, characterized in that, include: Step S1: Add the deoiled asphalt into the reactor, heat it to the first preset temperature, start stirring and melt it at the first stirring speed. During the melting process, the melting state is determined based on the real-time measured viscosity of the first asphalt melt, and the stirring speed is dynamically adjusted to obtain activated molten asphalt. Step S2: Determine the amount of 70# road petroleum asphalt to be added based on the penetration of the activated molten asphalt. After adding the asphalt, heat it to the second preset temperature to obtain the asphalt mixture raw material. Step S3: Based on the difference between the viscosity of the asphalt mixture and the viscosity of the first asphalt melt in step S1, determine the amount of SBS compatibilizer to be added, start the high-speed shear homogenizer to perform primary homogenization treatment with a preset shear speed and shear gap, and obtain preliminary mixed asphalt. Step S4: Transfer the preliminary mixed asphalt to an ultrasonic homogenizing device. Determine the initial power and frequency of the ultrasonic homogenizing device based on the difference between the particle size of Guangyuan rock asphalt in the preliminary mixed asphalt and the preset target particle size, and perform secondary homogenization treatment to obtain mixed asphalt. Step S5: When the particle size of the mixed asphalt reaches the preset target range, a rapid sample is taken and the microstructure of the sample is scanned to confirm that the SBS phase is in a continuous network shape, the rock asphalt particles are fully wrapped by the asphalt phase and there are no large-sized agglomerates. Step S6: After cooling the mixed asphalt to the third preset temperature, add the phase change material, start the paddle mixer and adjust the mixing speed to the second mixing speed. Adjust the mixing speed and mixing time based on the detected dispersion variation coefficient to obtain the mixed colloid. Step S7: The mixed colloid is fed into a twin-screw granulator, the barrel temperature is controlled in stages, and the temperature difference between adjacent sections is determined based on the dispersion variation coefficient, and cylindrical granules are extruded. Step S8: The cylindrical particles are cooled to room temperature by an air-cooled conveyor belt, sealed and packaged to obtain the finished hard asphalt masterbatch.

2. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 1, characterized in that, Step S1 includes: Step S11: Add the deoiled bitumen into the reactor and heat it to 150°C; Step S12: Start the anchor stirring and stir at 300 r / min for 30 min to melt; Step S13: Based on the result that the real-time measured asphalt melt viscosity is less than the preset viscosity threshold, it is determined that the deoiled asphalt has been activated. Based on the result that the real-time measured asphalt melt viscosity is greater than or equal to the preset viscosity threshold, it is determined that step S12 is repeated and the stirring speed is increased by 50 r / min.

3. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 2, characterized in that, Determining the amount of 70# road petroleum asphalt to be added in step S2 includes: Step S21: Obtain the measured penetration of the activated molten asphalt; Step S22: Calculate the first needle penetration difference value based on the difference between the measured needle penetration and the target needle penetration. Step S23: Calculate the second penetration difference value based on the difference between the measured penetration and the penetration of 70# road petroleum asphalt; Step S24: Calculate the blending ratio coefficient based on the ratio of the difference between the first needle penetration and the second needle penetration. Step S25: Calculate the amount of 70# road petroleum asphalt to be added based on the product of the activated molten asphalt mass and the blending ratio coefficient.

4. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 3, characterized in that, Determining the amount of SBS compatibilizer to be added in step S3 includes: Step S31: Obtain the viscosity of the asphalt mixture raw material; Step S32: Calculate the viscosity difference value based on the difference between the viscosity of the asphalt mixture and the viscosity of the first asphalt melt. Step S33: Calculate the amount of SBS compatibilizer added based on the product of the viscosity difference value and the basic amount of compatibilizer added.

5. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 4, characterized in that, Step S4 includes: Step S41: Maintain the system temperature at 165℃~170℃ and transfer it to an ultrasonic homogenization device; Step S42: Perform ultrasonic homogenization at 500W power and 20kHz frequency for 12 minutes; Step S43: During the processing, samples are taken every 3 minutes to detect the maximum particle size of the mixture; Step S44: Based on the result that the maximum particle size is greater than 10 μm, extend the ultrasonic treatment for 3 min and repeat step S43 until the maximum particle size is no greater than 10 μm.

6. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 5, characterized in that, Step S5 includes: Step S51: Sampling is performed when the particle size D90 of Guangyuan rock asphalt is detected to be less than or equal to 5 μm and continuously and stably greater than or equal to 3 minutes. Step S52: Obtain a microscopic image of the sample under 400x magnification and scan the microscopic image. If the area percentage of the SBS phase is greater than or equal to 30% and there are no asphalt aggregates greater than or equal to 20μm, the homogenization treatment is deemed qualified. If the area percentage of the SBS phase is less than 30% and there are asphalt aggregates greater than or equal to 20μm, repeat step S4.

7. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 6, characterized in that, In step S6, obtaining the dispersion coefficient of variation includes: Step S61: Detect the particle size distribution of the phase change material; Step S62: Calculate the standard deviation of the particle size and the average particle size of the phase change material; Step S63: Calculate the standard deviation of particle size and the average particle size to obtain the dispersion variation coefficient.

8. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 7, characterized in that, In step S6, based on the result that the dispersion variation coefficient is less than or equal to 15%, it is determined that the phase change material has been uniformly dispersed, and based on the result that the dispersion variation coefficient is greater than 15%, it is determined that the stirring time be extended by 10 minutes and the stirring speed be increased by 10%.

9. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to claim 8, characterized in that, Step S7 includes: Step S71: The mixed colloid is fed into a twin-screw granulator, wherein the screw speed of the twin-screw granulator is set to 150 r / min; Step S72: The barrel temperature is divided into three segments for control. The temperature difference between adjacent segments is determined based on the product of the dispersion coefficient of variation and the base regulating temperature. The preset temperature of Zone 1 is 100℃, the basic adjustment temperature is 10℃, the temperature of Zone 1 is lower than the temperature of Zone 2, and the temperature of Zone 2 is lower than the temperature of Zone 3. Step S73: Extrude molten strips through a cylindrical template with a die head aperture of 4mm; Step S74: The strip is cut into cylindrical particles with a particle size of 3mm to 5mm by a rotating cutter.

10. The method for preparing hard asphalt masterbatch based on low-temperature granulation according to any one of claims 1-9, characterized in that, The basic mass ratio of the hard asphalt masterbatch is: 40-50 parts deoiled asphalt, 20-25 parts Guangyuan rock asphalt, 5-8 parts phase change material, and 15-25 parts 70# road petroleum asphalt. The phase change material is PEG4000 or paraffin composite phase change material, and the SBS compatibilizer is YH-792.

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