A rock asphalt modified asphalt based on a wet activation process and a preparation method thereof

Abstract

The application provides a rock asphalt modified asphalt based on a wet activation process and a preparation method thereof, and relates to the field of asphalt.The rock asphalt modified asphalt comprises the following raw materials in parts by weight: 82-90 parts of base asphalt, 9-17 parts of pretreated buton rock asphalt and 0.3-1.2 parts of a composite activation additive; the composite activation additive is composed of oleic acid amide and terpene resin in a mass ratio of 2.5-3.5:0.8-1.2; the modified asphalt is prepared by using the wet activation process.The modified asphalt prepared by the application has low cost and high performance, can be better applied in road engineering, can realize high-temperature anti-rutting and low-temperature anti-cracking high-quality road performance, and can also achieve a low cost.

Description

Technical Field

[0001] This invention relates to the field of asphalt, and in particular to a rock asphalt modified asphalt based on a wet activation process and its preparation method. Background Technology

[0002] Asphalt pavement is the core load-bearing form of my country's road transportation system. While 70# road petroleum asphalt, a commonly used base asphalt, enjoys high application rates, its chemical composition limits its performance. This results in several shortcomings, including rutting at high temperatures, shrinkage and cracking at low temperatures, weak resistance to aging and water damage, and insufficient adhesion to aggregates. Consequently, its service life is significantly reduced in heavy traffic, high-temperature and rainy conditions, and cold regions, making it unsuitable for the long-term service requirements of modern roads. To compensate for these performance deficiencies, SBS modified asphalt has become the mainstream high-performance option. However, SBS modifiers are expensive, requiring strict temperature control during processing and incurring high costs for specialized equipment. Furthermore, the finished product is prone to problems such as segregation during storage, poor workability during construction, and a sharp decline in performance after aging, significantly increasing road construction and maintenance costs and limiting its large-scale application in economical and universal road projects.

[0003] Natural Buton rock asphalt, as a natural modified material with abundant reserves and low procurement costs, is rich in asphaltenes, resins, and inert minerals. It can effectively optimize the colloidal structure of asphalt and comprehensively improve road performance, making it a preferred material to replace expensive artificial modifiers. However, existing rock asphalt modified asphalt processing technology has obvious technical shortcomings: conventional dry blending only achieves shallow physical mixing, resulting in uneven dispersion of rock asphalt particles and insufficient release of internal active components, leading to negligible modification effects; traditional wet processes rely solely on simple stirring or shearing treatment, resulting in poor compatibility between rock asphalt and base asphalt, weak interfacial bonding, and easy segregation of the finished product, with limited performance improvement, achieving only simple compounding.

[0004] In summary, existing rock asphalt modified asphalt technologies generally suffer from core problems such as conventional processes, insufficient activation, and an imbalance between performance and cost, making it difficult to meet the actual needs of road engineering for "low-cost, high-performance, easy-to-construct, and highly stable" modified asphalt. Summary of the Invention

[0005] In view of this, the present invention proposes a rock asphalt modified asphalt based on a wet activation process and its preparation method.

[0006] This invention uses base asphalt as the main material, combined with natural Buton rock asphalt, compounded with trace amounts of activating additives, and supplemented with a wet activation process to produce highly stable rock asphalt modified asphalt. This product is suitable for heavy-duty traffic highways, urban arterial roads, municipal road networks, and old road surface renovation projects. It has better performance than ordinary asphalt, lower cost, and has the dual core advantages of cost reduction and efficiency improvement as well as long-term road use.

[0007] Furthermore, traditional rock asphalt-modified asphalt technologies generally suffer from problems such as insufficient activation and an imbalance between performance and cost, making it difficult to meet the actual needs of road engineering for "low-cost, high-performance, easy-to-construct, and highly stable" asphalt. Therefore, developing a rock asphalt-modified asphalt with better performance and storage stability, while balancing cost control and performance upgrades, is of great significance to the development of road asphalt materials.

[0008] The technical solution of this invention is implemented as follows: A rock asphalt modified asphalt based on a wet activation process comprises the following raw materials in parts by weight: 82-90 parts of base asphalt, 9-17 parts of pretreated Buton rock asphalt, and 0.3-1.2 parts of composite activation additive; wherein the composite activation additive is composed of oleic acid amide and terpene resin in a mass ratio of 2.5-3.5:0.8-1.2.

[0009] Furthermore, the base asphalt includes at least one of 70# road petroleum base asphalt, 90# road petroleum base asphalt, and 110# road petroleum base asphalt.

[0010] Furthermore, the method for preparing the pretreated Buton rock bitumen includes the following steps: (1) Buton rock asphalt is selected, with an asphalt content ≥22%; (2) First, dehydrate under vacuum at 60-70℃ for 4-6 hours; then, mechanically grind and air classify the particles to control the particle size at 120-200 mesh; finally, use low-temperature plasma surface roughening treatment at 60-80℃, vacuum degree 10-40Pa, power 80-120W, and treatment time 3-5 minutes, and store in a sealed, dry place.

[0011] Furthermore, the preparation method of the composite activating agent includes the following steps: heating oleic amide to 60-70℃ to melt, then adding solid terpene resin, stirring at a constant temperature for 20-40 minutes, cooling to room temperature, and then sealing and storing.

[0012] This invention also provides a method for preparing rock asphalt modified asphalt based on a wet activation process, comprising the following steps: (1) Gradient preheating and melting of base asphalt (basic material preparation process): Weigh the base asphalt according to the proportion, add it into the reactor, turn on the heat transfer oil heating system and stirring device, and perform gradient heating operation: the first stage heats up to 130-140℃, the stirring speed is 250-350r / min, and the low speed is stirred for 8-12min to break up the base asphalt lumps at room temperature and initially melt it; the second stage heats up to 150-158℃, the stirring speed is adjusted to 350-450r / min, and the constant temperature is stirred for 18-25min; until the base asphalt is completely melted and there are no solid lumps.

[0013] This step avoids the problems of asphalt aging and volatilization of lightweight components caused by conventional one-time high-temperature heating, ensuring the fluidity and component stability of the base asphalt, and providing a uniform liquid phase environment for subsequent rock asphalt blending.

[0014] (2) Stepwise swelling and premixing of rock asphalt (pre-dispersion and activation process): Keep the temperature of the reactor stable at 150-158℃, start the automatic feeding device, and add the pretreated Buton rock asphalt to the molten matrix asphalt in 2-4 batches; after the feeding is completed, add the composite activation additive and continue stirring until the system is uniform. Among them, the interval between each feeding is 6-9 minutes, the stirring speed is increased to 500-650 r / min throughout the feeding process, and the stirring is kept at a constant temperature after all the materials are fed to complete the initial swelling and dispersion; then add the specified amount of composite activation additive, reduce the speed to 250-350 r / min, and stir at low speed for 5-8 minutes to make the additive uniformly coat the rock asphalt particles and activate the surface active sites.

[0015] This step avoids the agglomeration and clumping of rock asphalt by feeding it in stages. It utilizes a constant temperature environment to allow the rock asphalt particles to fully swell and dissolve, and with the help of additives, it achieves preliminary dispersion and activation, laying the foundation for subsequent deep activation. Precautions: The feeding speed should be controlled at 0.5-1 kg / min to prevent dust from flying. The absence of visible rock asphalt agglomerates is considered a premixed form.

[0016] (3) Multi-field coupling wet activation: After premixing, close the feeding port, strengthen the sealing of the vessel, turn on the heat transfer oil heating system, and heat the mixture at a uniform rate to 168-178℃. First, start the ultrasonic-assisted activation system for cavitation dispersion, and then switch to the high-speed shear machine for wet shearing. During the ultrasonic-assisted stage, use intermittent ultrasonic mode for dispersion. Then, turn off the ultrasonic system, turn on the high-speed shear machine, and perform wet shearing activation to ensure uniform shearing throughout the vessel.

[0017] This step utilizes ultrasonic cavitation to break up rock asphalt micro-agglomerates and remove internal active asphaltenes. Then, high-speed shearing is used to achieve the mutual solubility and interfacial chemical bonding of rock asphalt and matrix asphalt, thus optimizing the problems of uneven dispersion and insufficient activation of rock asphalt.

[0018] (4) Temperature-controlled crosslinking maturation and stabilization (finished product shaping process): After activation, turn off the high-speed shearing machine, turn on the autoclave cooling system, and perform a step-down cooling operation to control the temperature and mature in stages, and finally keep it warm and sealed for storage. Among them, the step-down cooling operation is as follows: the first stage is to cool down to 152-158℃, adjust the stirring speed to 250-350r / min, and mature at a constant temperature for 30-40min; the second stage is to cool down to 130-138℃, reduce the stirring speed to 150-200r / min, and stir at low speed for 8-12min to further stabilize the asphalt colloidal structure.

[0019] This step, through stepped cooling and constant-temperature curing, allows the modified asphalt system to fully cross-link and stabilize, avoiding problems such as stratification, segregation, and uneven soft spots in the finished product, and improving storage stability and workability.

[0020] Further, in step (1), the second stage involves heating at a constant rate of 3-5℃ / min.

[0021] Furthermore, in step (2), the feeding speed is controlled at 0.5-1 kg / min.

[0022] Further, in step (2), the pretreated Buton rock asphalt is added to the molten matrix asphalt in 2-4 equal portions; the constant temperature stirring temperature is 150-158℃, and the stirring time is 25-32min.

[0023] Further, in step (3), the ultrasonic dispersion specifically involves using an intermittent ultrasonic mode for 12-18 minutes, with the intermittent ultrasonic mode being on for 25-35 seconds and off for 8-12 seconds, the ultrasonic frequency being 25-35 kHz, and the ultrasonic power being 800-1200 W.

[0024] Furthermore, in step (3), during the wet shearing activation process, the shearing disc is immersed in 2 / 3 of the mixture liquid surface; the wet shearing speed is 4000-5500 r / min, and the wet shearing time is 35-45 min.

[0025] Further, in step (4), the first stage involves rapid cooling at a rate of 5-8℃ / min.

[0026] Further, in step (4), the second stage involves slow cooling at a rate of 1-2 °C / min.

[0027] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention adopts a specific component compound system formulation: with matrix asphalt, pretreated Buton rock asphalt and composite activating agent as the core, and the weight ratio range of each component, taking into account both low cost and high performance.

[0028] (2) Key technologies for raw material pretreatment: The pretreatment process of Buton rock asphalt is a three-step pretreatment method that involves low-temperature vacuum dehydration, grinding and grading, and low-temperature plasma surface roughening, as well as corresponding moisture content, particle size and activity control indicators, which is different from the conventional method of directly feeding raw rock asphalt.

[0029] (3) Refined wet activation core process: abandoning the traditional four-step wet process of gradient preheating and melting, step-by-step swelling and premixing, multi-field coupling activation, and step-temperature cross-linking and maturation, which is different from the existing process.

[0030] (4) Key protection of finished product performance and application: High-stability rock asphalt composite modified asphalt finished product with lower cost than ordinary base asphalt and performance between ordinary asphalt and SBS modified asphalt, prepared by the above process and formula, and protection of the application of the product in road engineering.

[0031] (5) This invention makes targeted improvements to address the core defects of traditional dry and wet rock asphalt modification processes. Relying on pretreatment technology, additives, and refined wet processes, its advantages also include the following aspects: To address the problems of uneven dispersion, insufficient activation, and easy stratification and segregation in traditional processes, this invention pre-treats rock asphalt, combines it with a composite activation additive to break down interfacial barriers, and then uses a coupled activation process to achieve mutual solubility of raw materials. As a result, the finished product is free from stratification and segregation, is fully activated, and has a better modification effect than traditional processes. To address the problems of asphalt aging, poor performance, and cost imbalance caused by the crude temperature control and single shearing of traditional processes, this invention adopts gradient step precise temperature control to avoid asphalt aging. At the same time, it relies on rock asphalt to reduce raw material costs, achieving both high-temperature rutting resistance and low-temperature crack resistance in road applications, while also being affordable. Detailed Implementation

[0032] Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods; Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available. Mechanical grinding equipment used for Buton bitumen pretreatment: VRERA brand solid pulverizer YXA-4; The air classifier used in Buton asphalt pretreatment is the Huimeike HMK-200 air classifier. Rotary drum type low-temperature plasma treatment instrument: VP-R5 rotary drum type low-temperature plasma treatment instrument; Ultrasonic disperser: JZFS-28 high-frequency ultrasonic disperser; High-speed shearing machine: Weiguang BME100L high-speed shearing machine.

[0033] Example 1 (Experimental Group 1) A rock asphalt modified asphalt based on a wet activation process is prepared from the following raw materials in parts by weight: 85 parts of 70# road petroleum matrix asphalt, 14.6 parts of pretreated Buton rock asphalt, and 0.4 parts of composite activation additive; the composite activation additive is composed of vegetable oleic acid amide and terpene resin in a mass ratio of 3:1.

[0034] I. Raw Material Processing The specific components and indicator requirements are as follows: Performance indicators of 1.70# road petroleum base asphalt: penetration at 25℃ 60-80 (0.1mm), softening point ≥46℃, ductility at 15℃ ≥100cm, flash point ≥260℃, dynamic viscosity at 60℃ ≥180Pa·s, wax content ≤2.2%, solubility ≥99.5%.

[0035] 2. Pretreatment of Buton rock asphalt: (1) The raw material is Indonesian Buton rock asphalt with an asphalt content of ≥22%, sufficient organic matter, and minerals mainly composed of silicon dioxide and calcium carbonate. It does not contain harmful impurities such as heavy metals. (2) Pretreatment process: First, the material is dehydrated at a low temperature of 60-70℃ for 4-6 hours, and the moisture content is strictly controlled to ≤0.8% to avoid uneven mixing caused by air bubbles during processing; then, it is mechanically ground and air classified to control the particle size to 120-200 mesh, with uniform particles and no lumps; finally, a low temperature plasma surface roughening treatment is adopted, with a treatment temperature of 60-80℃, a vacuum degree of 10-40Pa, a power of 80-120W, and a treatment time of 3-5 minutes to improve the surface roughness and number of active sites of rock asphalt and strengthen the interfacial bonding force with the matrix asphalt. The aforementioned low-temperature plasma surface roughening treatment equipment and treatment conditions are as follows: ① Processing equipment: A rotary low-temperature plasma treatment instrument is used; ② Processing gas: A mixture of argon (Ar) and oxygen (O2) is used, with a volume ratio of 9:1. Argon serves as an inert carrier gas, mainly playing a physical sputtering etching role, which can form a rough structure on the rock asphalt surface and remove the surface inert oxide layer. Oxygen serves as a reactive gas, which can help introduce polar functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups, increase the surface active sites, and improve the compatibility with the matrix asphalt and composite activation aids. The total flow rate of the mixed gas is controlled at 20-50 sccm. ③ Processing parameters: The processing power is controlled at 80-120W, the processing time is 3-5min; the processing temperature is controlled at 60-80℃ to avoid sudden temperature changes that may cause rock asphalt particles to agglomerate or deteriorate in performance; the vacuum degree is controlled at 10-40Pa; the equipment working frequency is 40kHz, and the drum speed is adjusted to 30r / min. ④ Specific operating steps: First, evenly load the ground and graded rock asphalt powder into the detachable rotating drum of the equipment, close and seal the equipment cavity; start the vacuum system and evacuate the vacuum degree in the cavity to 10-40 Pa; introduce a mixture of argon and oxygen (volume ratio 9:1), adjust the gas flow rate to 20-50 sccm, and keep the internal gas pressure of the cavity stable at 10-40 Pa; turn on the plasma generator, adjust the power to 80-120W and the working frequency to 40kHz, start the rotating drum (speed 30r / min), and begin the surface roughening treatment for 3-5 minutes; after the treatment is completed, first turn off the plasma generator, stop the introduction of the mixed gas, slowly depressurize to normal pressure, then open the cavity to take out the rock asphalt powder, and immediately transfer it to a sealed dry container for storage to prevent oxidation or moisture absorption of the surface active sites.

[0036] (3) Storage requirements: Pretreated rock asphalt must be sealed and dried to prevent moisture absorption and clumping. Agglomerated particles must be thoroughly removed before feeding.

[0037] 3. Composite activating agent: This is a component that activates rock asphalt and stabilizes asphalt colloids, as detailed below: (1) Components and selection of auxiliary agents It is formulated by compounding plant oleic acid amide and terpene resin in a specific mass ratio: ① Plant oleic acid amide: purity ≥95%, free of mechanical impurities and free acids and bases, iodine value ≤80g / 100g, acid value ≤10mgKOH / g; ② Terpene resin: esterified modified terpene resin is selected, softening point 90-110℃, acid value ≤1mgKOH / g, ash content ≤0.05%.

[0038] (2) Mechanism of compounding of adjuvants When the two components are compounded in a 3:1 mass ratio, a composite additive with three functions—dispersion and activation, interface modification, and colloidal stabilization—is formed, specifically as follows: ① Dispersion and agglomeration: The plant oleic acid amide molecules contain long-chain alkyl and amide polar groups, which can penetrate the gaps between rock asphalt micro-agglomerates, reduce the interparticle interfacial energy, break up rock asphalt agglomerates, and at the same time reduce the interfacial resistance between rock asphalt and matrix asphalt, helping rock asphalt particles to be uniformly dispersed in matrix asphalt, solving the problem of uneven dispersion of rock asphalt in conventional processes; ② Activation and synergistic effect: The amide polar groups can interact with the active sites on the surface of rock asphalt and in the matrix asphalt. The resin and asphaltenes form hydrogen bonds, activating the inert asphaltenes inside the rock asphalt, promoting molecular-level miscibility and interfacial bonding between the rock asphalt and the base asphalt, greatly improving the efficiency of wet activation, and making the modification effect far exceed that of conventional physical blending; ③ Colloidal stabilizing effect: As a cross-linking reinforcing component, terpene resin can be embedded in the asphalt colloidal structure, filling the gaps between the resin and asphaltenes, improving the cohesive strength of the asphalt colloidal, and inhibiting the segregation of modified asphalt during storage and transportation, solving the common industry problem of poor storage stability of rock asphalt modified asphalt, and also slightly optimizing the high-temperature rutting resistance and low-temperature ductility of asphalt.

[0039] (3) Requirements for quality control and addition of additives ① Compounding requirements: The vegetable oil amide needs to be heated to 60-70℃ to melt beforehand, and then solid terpene resin is added in proportion. Stir at a constant temperature for 30 minutes until completely miscible. After cooling to room temperature, seal and store. ② Storage requirements: Store at room temperature in a dry place away from light. The storage temperature should be ≤35℃. Before adding the additive, check its state. It can only be used if it is a uniform viscous liquid without layering or impurities. ③ Addition requirements: It must be added in the later stage of rock asphalt premixing to ensure that the additive first coats the rock asphalt particles before entering the activation stage.

[0040] II. Preparation method and processing steps Abandoning the conventional wet process of simple mixing and shearing, a four-step process is adopted: gradient preheating and melting of base asphalt → stepwise swelling and premixing of rock asphalt → multi-field coupled wet activation → temperature-controlled crosslinking curing and stabilization. The specific steps are as follows: Step 1: Gradient preheating and melting of base asphalt (basic material preparation process) Weigh out 70# road petroleum base asphalt according to the mixing ratio, add it to the reactor, turn on the heat transfer oil heating system and stirring device, and perform gradient heating operation: the first stage heats up to 130-140℃, the stirring speed is 300r / min, and the stirring is done at low speed for 10min to break up the base asphalt lumps at room temperature and initially melt it; the second stage heats up at a rate of 3-5℃ / min at a uniform rate to 150-158℃, the stirring speed is adjusted to 350-450r / min, and the stirring is done at a constant temperature for 18-25min until the base asphalt is completely melted and there are no solid lumps.

[0041] Step 2: Stepwise swelling and premixing of rock asphalt (pre-dispersion and activation process) Maintain a stable reactor temperature of 150-158℃, start the automatic feeding device, and slowly add the pretreated Buton rock asphalt to the molten matrix asphalt in three equal portions. After feeding, add the composite activating agent and continue stirring until the system is homogeneous. Each rock asphalt feeding should be spaced 6-9 minutes apart, with the stirring speed increased to 500-650 r / min throughout the feeding process. After all materials have been fed, maintain a constant temperature (150-158℃) and stir for 25-32 minutes to complete the initial swelling and dispersion. Then add the specified amount of composite activating agent, reduce the stirring speed to 300 r / min, and stir at low speed for 5-8 minutes to ensure the agent evenly coats the rock asphalt particles and activates surface active sites. The feeding speed should be controlled at 0.5-1 kg / min to prevent dust from flying. The absence of visible rock asphalt agglomerates indicates a premixed state.

[0042] Step 3: Multi-field coupled wet activation After premixing, close the feeding port, strengthen the vessel seal, and turn on the heat transfer oil heating system to uniformly heat the mixture to 168-178℃. First, start the ultrasonic-assisted activation system (ultrasonic disperser) for cavitation dispersion, and then switch to the high-speed shear for wet shearing. During the ultrasonic-assisted stage, adjust the ultrasonic frequency to 25-35kHz and the ultrasonic power to 800-1200W, and use an intermittent ultrasonic mode (on for 30 seconds, off for 10 seconds) to disperse for 12-18 minutes (including the time for each "off for 10 seconds") to avoid local overheating. Then, turn off the ultrasonic system, turn on the high-speed shear, adjust the shearing speed to 4000-5500r / min, and perform wet shear activation for 35-45 minutes. Immerse the shearing disc to 2 / 3 of the liquid surface of the mixture to ensure uniform shearing throughout the vessel.

[0043] Step 4: Temperature-controlled cross-linking, curing, and stabilization (finished product shaping process) After activation, the high-speed shearing machine is turned off, the autoclave cooling system is turned on, and a stepped cooling operation is performed. The autoclave is then matured in stages with controlled temperature, and finally sealed and stored. In the first stage, the temperature is rapidly reduced to 152-158℃ at a rate of 5-8℃ / min, the stirring speed is adjusted to 250-350r / min, and the autoclave is matured at a constant temperature for 30-40min to eliminate the internal stress generated during activation. In the second stage, the temperature is slowly reduced to 130-138℃ at a rate of 1-2℃ / min, the stirring speed is reduced to 200r / min, and the autoclave is stirred at a low speed for 10min to further stabilize the asphalt colloidal structure.

[0044] Example 2 (Experimental Group 2) Based on Example 1, the amount of base asphalt is reduced and the amount of pretreated Buton rock asphalt is increased. A rock asphalt modified asphalt based on a wet activation process is prepared from the following raw materials in parts by weight: 83 parts of 70# road petroleum base asphalt, 16.6 parts of pretreated Buton rock asphalt, and 0.4 parts of composite activation additive; the composite activation additive is composed of vegetable oleic acid amide and terpene resin in a mass ratio of 3:1.

[0045] Experimental group 3 (Comparative example 1) Based on Example 1, only oleamide was used as a single additive, without the addition of terpene resin. A rock asphalt modified asphalt based on a wet activation process was prepared from the following raw materials in parts by weight: 85 parts of 70# road petroleum base asphalt, 14.6 parts of pretreated Buton rock asphalt, and 0.4 parts of vegetable oleamide.

[0046] Experimental group 4 (Comparative example 2) Based on Example 1, only terpene resin was used as a single additive, and the oleic acid amide component was removed. A rock asphalt modified asphalt based on a wet activation process was prepared from the following raw materials in parts by weight: 85 parts of 70# road petroleum base asphalt, 14.6 parts of pretreated Buton rock asphalt, and 0.4 parts of terpene resin.

[0047] Experimental group 5 (Comparative example 3) Based on Example 1, no composite activating agents are used, i.e., no vegetable oleic acid amides and terpene resins are added. A rock asphalt modified asphalt based on a wet activation process is prepared from the following raw materials in parts by weight: 85 parts of 70# road petroleum base asphalt and 15 parts of pretreated Buton rock asphalt.

[0048] Experimental group 6 (Comparative example 4) All samples used 70# road petroleum base asphalt, that is, pure 70# base asphalt was used as a blank control, without adding any rock asphalt or modifying additives, and without any special modification process.

[0049] Experimental group 7 (Comparative example 5) All samples used SBSI-D modified asphalt as a positive control (high-performance control). SBS ID modified asphalt is the highest grade (Grade D) of Class I modified asphalt in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40).

[0050] Experimental group 8 (Comparative example 6) The main difference from Example 1 is that the refined wet process is replaced with a conventional simple wet process, lacking the steps of step-by-step swelling, coupled activation, and stepped maturation. Specifically, after all materials are premixed, the feeding port is closed, the heat transfer oil heating system is turned on, and the mixture is heated to 165-170°C at a uniform rate. The shearing machine is then turned on for wet shearing activation, and the shearing speed is adjusted to 3500-4000 r / min, so that the shearing disc is immersed in 2 / 3 of the mixture. The temperature is kept constant at 165-170°C, and shearing is continued for 35 minutes. After shearing is completed, the shearing machine is turned off and cooled to room temperature.

[0051] Experimental group 9 (Comparative example 7) The main difference from Example 1 is that no composite activating agent was added, and a dry modification process was used: dry blending (the base asphalt was directly added and coarsely mixed after melting, without a wet process).

[0052] A rock asphalt modified asphalt is prepared from the following raw materials in parts by weight: 85 parts of 70# road petroleum base asphalt and 15 parts of pretreated Buton rock asphalt. The specific preparation method is as follows: Weigh the 70# road petroleum base asphalt according to the proportion and add it to a reaction vessel. Turn on the heat transfer oil heating system and stirring device to heat the base asphalt to 150-158℃ and melt it completely. Add the pretreated Buton rock asphalt into the molten base asphalt in one go, premixing without swelling. Turn on the stirring device and adjust the speed to 500-650 r / min for coarse mixing. Maintain a constant temperature of 150-158℃ and continue coarse mixing until there are no obvious visible rock asphalt agglomerates. Then cool down.

[0053] Experimental group 10 (Comparative example 8) The main difference from Example 1 is that the pretreated Buton rock bitumen was replaced with conventional rock bitumen, i.e., the Buton rock bitumen before pretreatment had the following characteristics: appearance: dark brown to black powder, no visible impurities, uniform color, no lumps; water content ≤2.5%; chloroform solubility ≥25%; asphaltene content: 22±2%; and impurity content such as mud and sand ≤1%. The effect of rock bitumen pretreatment was investigated.

[0054] Experimental group 11 (Comparative example 9) Further adjustments were made to Experiment Group 8, with the main difference being that the pretreated Buton rock asphalt was replaced with conventional rock asphalt (i.e., the Buton rock asphalt before pretreatment), which was the same as in Experiment Group 10. The effects of the wet process and rock asphalt pretreatment were further investigated.

[0055] Experimental group 12 (Comparative example 10) Further adjustments were made to Experiment Group 9, with the main difference being that the pretreated Buton rock asphalt was replaced with conventional rock asphalt (i.e., the Buton rock asphalt before pretreatment), which was the same as in Experiment Group 10. The influence of conventional dry process and rock asphalt pretreatment was further investigated.

[0056] The products in test groups 1-12 were tested, and the test results for test groups 1-12 are shown in Table 1 below: Table 1 Test Results of Experimental Indicators

[0057] The technical specifications for AC-13 rock asphalt modified asphalt mixtures are shown in Table 2 below: Table 2 Technical Specifications of AC-13 Rock Asphalt Modified Asphalt Mixture

[0058] AC-13 mixtures (fine-grained dense-graded asphalt concrete) were prepared using products from test groups 1-12 respectively, and the performance of the mixtures was tested. The dosage of products from test groups 1-12 in the mixtures was 5%. The test results for various indicators are shown in Table 3 below. Table 3 Results of performance testing of the mixture

[0059] Experimental Group 1, as the basic scheme of this invention, adopts a combination of pretreated rock asphalt, composite activating agents, and refined wet process. Because the rock asphalt is dehydrated, ground, and surface-treated in advance, the problems of high water content, large surface inertia, and incompatibility with matrix asphalt of virgin rock asphalt are solved. In addition, the composite additive helps to disperse and stabilize the colloidal structure. Then, the refined wet process allows the rock asphalt to fully swell, activate, and distribute evenly. Therefore, the asphalt has moderate softness and hardness, significantly improved high-temperature performance, and stable storage. Correspondingly, in the mixture, it not only ensures sufficient high-temperature rutting resistance, but also has a good bonding effect between asphalt and aggregate. The water stability is much better than that of conventional asphalt, and all performances are balanced and fully meet the standards.

[0060] Based on the technology of Experiment 1, Experiment 2 only increased the amount of pretreated Buton rock asphalt, while keeping the other pretreatment, additives and process conditions the same. The addition of more pretreated Buton rock asphalt can further improve the hardness and high-temperature viscosity of the asphalt. Therefore, the high-temperature stability of the mixture is closer to that of SBS modified asphalt. At the same time, thanks to the pretreatment and process guarantee, the rock asphalt can still be evenly dispersed and bond well with the aggregate. The water stability performance is also slightly improved. Only the low-temperature ductility is slightly reduced. Overall, it still maintains an excellent level.

[0061] In Experiment Group 3, only oleic acid amide was used as a single additive, and the terpene resin component was removed. Although oleic acid amide can play a certain dispersing role, the lack of terpene resin's thickening and stabilizing effect on asphalt colloid resulted in rock asphalt being only initially dispersed in asphalt and unable to form a stable colloidal structure. Consequently, the high-temperature viscosity and storage stability of the asphalt decreased, and its high-temperature rutting resistance and water stability were weaker than those of Experiment Group 1.

[0062] Experimental group 4 used only terpene resin as a single additive, removing the oleamide component. Although terpene resin can improve the viscosity and high-temperature performance of asphalt, it lacks the dispersing and lubricating effect of oleamide. Rock asphalt is difficult to fully disperse in the base asphalt, and local agglomeration is likely to occur, which makes the low-temperature ductility of asphalt worse. The mixture is prone to embrittlement at low temperatures. At the same time, uneven dispersion will also affect the bonding effect between asphalt and aggregate, and the water stability will be reduced accordingly. The overall modification effect is significantly worse than the scheme with two-component compound additives.

[0063] Experimental group 5 did not use any composite activating additives and relied solely on the process to blend and modify the pretreated rock asphalt. Due to the lack of additives to assist in dispersion, activation and stabilization, the interfacial barrier between the rock asphalt and the base asphalt could not be effectively broken. Even after pretreatment and fine mixing, the activation degree of the rock asphalt was still limited, the high temperature increase of the asphalt was small and the storage stability was average. The modification effect of the mixture was greatly weakened, only slightly better than ordinary 70# asphalt.

[0064] Experimental group 6 used pure 70# base asphalt as a blank control, without adding any rock asphalt or modifying additives, and without any special modification process, as the baseline group.

[0065] Experimental group 7 used SBS modified asphalt as a high-performance control (positive control).

[0066] Experimental group 8 used pretreated rock asphalt and composite additives, but changed the refined wet process to a conventional simple wet process. It lacked the steps of step swelling, coupled activation and stepped maturation. The rock asphalt could only achieve preliminary blending and could not be fully activated. The internal effective components could not be fully released, resulting in the high temperature performance and storage stability of the asphalt being inferior to that of Scheme 1. The high temperature rutting resistance and water stability of the mixture were also reduced accordingly.

[0067] Although pretreated rock asphalt was used in test group 9, no additives were added and dry construction was adopted. Dry construction is just a simple physical mixing of rock asphalt, aggregate and asphalt. Rock asphalt cannot be integrated into the matrix asphalt to form a uniform system. There are no additives to improve the adhesion with the aggregate. As a result, the asphalt itself has poor uniformity and serious segregation. The bonding strength between the asphalt and the aggregate in the mixture is insufficient. Under the action of water erosion, it is very easy to peel off. The water stability index cannot meet the standard. The high temperature and low temperature performance is also deteriorated.

[0068] In Experiment Group 10, untreated virgin rock asphalt was used in combination with composite additives and a refined wet process. The virgin rock asphalt had strong surface inertness and high water content, making it difficult to fundamentally improve its dispersibility and compatibility. The rock asphalt could not fully exert its modifying effect, and the high-temperature performance and storage stability of the asphalt were weaker than those of the pretreated solution. Consequently, the high-temperature rutting resistance and water stability of the mixture were reduced.

[0069] Experimental group 11 used untreated virgin rock asphalt and conventional wet process, retaining composite additives. The virgin rock asphalt itself had poor dispersibility, and the conventional wet process was insufficient in activation, resulting in the rock asphalt being unable to be effectively dispersed and activated. The asphalt colloidal structure was unstable and segregation was obvious. The mixture not only had lower high-temperature performance than ordinary 70# asphalt, but the bonding effect between asphalt and aggregate was also greatly reduced. The freeze-thaw splitting strength ratio could not meet the specification requirements, and there were obvious defects in road performance.

[0070] Experimental group 12 used untreated virgin rock asphalt, no activating additives, and dry construction, which is the worst combination for traditional rock asphalt applications. The rock asphalt was neither pretreated to improve its condition nor aided by additives for dispersion. It was simply mixed by dry method, which could not achieve effective modification at all. The rock asphalt was just mechanically added to the mixture. There was almost no reliable bond between the asphalt and the aggregate. The mixture had a large porosity and insufficient strength. Key indicators such as high temperature, water stability, and low temperature were all not up to standard.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A rock-modified asphalt based on a wet activation process, characterized in that, The raw materials include the following parts by weight: 82-90 parts of base bitumen, 9-17 parts of pretreated Buton rock bitumen, and 0.3-1.2 parts of composite activating agent; the composite activating agent is composed of oleic acid amide and terpene resin in a mass ratio of 2.5-3.5:0.8-1.

2.

2. The rock asphalt modified asphalt based on wet activation process according to claim 1, characterized in that, The base asphalt includes at least one of 70# road petroleum base asphalt, 90# road petroleum base asphalt, and 110# road petroleum base asphalt.

3. The rock asphalt modified asphalt based on wet activation process according to claim 1, characterized in that, The method for preparing the pretreated Buton rock bitumen includes the following steps: (1) Buton rock asphalt is selected, with an asphalt content ≥22%; (2) First, dehydrate under vacuum at 60-70℃ for 4-6 hours; then, mechanically grind and air classify the particles to control the particle size at 120-200 mesh; finally, use low-temperature plasma surface roughening treatment at 60-80℃, vacuum degree 10-40Pa, power 80-120W, and treatment time 3-5 minutes, and store in a sealed, dry place.

4. The rock asphalt modified asphalt based on wet activation process according to claim 1, characterized in that, The preparation method of the composite activator includes the following steps: heating oleic amide to 60-70℃ to melt, then adding terpene resin, stirring at a constant temperature for 20-40 minutes, cooling to room temperature, and then sealing and storing.

5. The method for preparing rock asphalt modified asphalt based on wet activation process according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Weigh the base asphalt according to the proportion, add it into the reactor, and perform gradient heating and stirring: in the first stage, heat the asphalt to 130-140℃, stir at 250-350r / min, and stir at low speed for 8-12min; in the second stage, heat the asphalt to 150-158℃, adjust the stirring speed to 350-450r / min, and stir at constant temperature for 18-25min. To obtain molten matrix bitumen; (2) Keep the temperature of the reactor stable at 150-158℃, and add Buton rock bitumen to the molten matrix bitumen in step (1) in 2-4 portions; After the feed is completed, add the composite activating agent and continue stirring until the system is uniform to obtain the mixture; (3) Heat the mixture to 168-178℃, first disperse it with ultrasonication, and then switch to a high-speed shear machine for wet shearing activation; (4) After activation, perform a step cooling operation and staged temperature control for maturation. In the first stage, the temperature is lowered to 152-158℃, the stirring speed is adjusted to 250-350r / min, and the temperature is kept constant for 30-40min. In the second stage, the temperature is lowered to 130-138℃, the stirring speed is reduced to 150-200r / min, and the stirring speed is kept low for 8-12min. Finally, it is stored in an insulated and sealed container.

6. The method for preparing rock asphalt modified asphalt based on wet activation process according to claim 5, characterized in that, Step (1): The second stage involves heating at a uniform rate of 3-5℃ / min; Step (2): The feeding speed is controlled at 0.5-1kg / min.

7. The method for preparing rock asphalt modified asphalt based on wet activation process according to claim 5, characterized in that, Step (2): Add the pretreated Buton rock asphalt to the molten matrix asphalt in 2-4 equal portions; Each feeding interval is 6-9 minutes. The stirring speed is increased to 500-650 r / min throughout the feeding process. After all materials are fed, the mixture is stirred at a constant temperature. The constant temperature stirring temperature is 150-158℃, and the stirring time is 25-32 minutes; After adding the composite activating agent, reduce the rotation speed to 250-350 r / min and stir for 5-8 min.

8. The method for preparing rock asphalt modified asphalt based on wet activation process according to claim 5, characterized in that, Step (3), the ultrasonic dispersion specifically: use intermittent ultrasonic mode for ultrasonic dispersion for 12-18 minutes, the intermittent ultrasonic mode is on for 25-35 seconds and off for 8-12 seconds, the ultrasonic frequency is 25-35 kHz and the ultrasonic power is 800-1200 W.

9. The method for preparing rock asphalt modified asphalt based on wet activation process according to claim 5, characterized in that, In step (3), during the wet shearing activation process, the shearing disc is immersed in 2 / 3 of the mixture liquid surface; the wet shearing speed is 4000-5500 r / min, and the wet shearing time is 35-45 min.

10. The method for preparing rock asphalt modified asphalt based on wet activation process according to claim 5, characterized in that, Step (4): In the first stage, the temperature is rapidly reduced at a rate of 5-8℃ / min; in the second stage, the temperature is slowly reduced at a rate of 1-2℃ / min.

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