High-content rubber powder composite Kelan No. 90 modified asphalt and preparation process thereof

Abstract

The invention relates to the technical field of road engineering materials, and discloses high-content rubber powder composite Ke-smelted 90 # modified asphalt and a preparation process thereof, the modified asphalt is prepared by compounding Ke-smelted 90 # matrix asphalt, 10%-20% rubber powder, SBS, a viscosity reducer, nano calcium carbonate, a coupling agent and surlyn resin; the preparation method comprises the following steps: rapidly heating the matrix asphalt, performing staged and multi-stage mixing, performing high-shear grinding, and performing fine dispersion by a colloid mill. According to the invention, high-valued utilization of waste resources is realized, pavement performance and construction convenience of the modified asphalt are remarkably improved, the problems of segregation and overhigh viscosity of high-content rubber powder are solved, and the product has excellent softening point, ductility and elastic recovery rate and low construction viscosity.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, specifically relating to a high-content rubber powder composite 90-grade modified asphalt and its preparation process. Background Technology

[0002] Waste recycling has become an important pathway to achieving sustainable development. Especially in the field of transportation infrastructure construction, the optimization of asphalt, a core material, and the incorporation of environmentally friendly materials play a crucial role in improving road service levels, extending service life, and reducing life-cycle carbon emissions. Waste tires, as a typical, widely distributed, and non-degradable polymeric waste, not only occupy significant land resources when improperly dumped, but also pose a long-term threat to the ecological environment. Traditional waste tire disposal methods, such as landfilling or incineration, lead to serious environmental problems and fail to achieve effective resource recycling.

[0003] To address the challenges of waste tire disposal and improve the performance of asphalt pavements, the industry has developed a series of technological approaches, among which processing waste tires into rubber powder and then using it as a modifier in asphalt concrete is the most common. Specifically, this method typically involves mechanically crushing, desulfurizing, and finely granulating the waste tires to obtain rubber powder with uniform particle size and enhanced surface activity. Subsequently, this pre-treated rubber powder is incorporated into the base asphalt, and through physical blending or certain chemical cross-linking, modified asphalt with excellent elasticity, ductility, and high-temperature stability is formed. This modified asphalt can effectively improve the pavement's resistance to fatigue cracking, its ability to resist rutting deformation, and reduce noise, thereby significantly improving road performance and durability. For a considerable period, this technological approach has achieved significant technological progress and application results in simultaneously solving waste disposal and improving road material performance, laying a solid foundation for the development of asphalt modification technology. The design principle lies in using refined processing to create a relatively stable dispersion system between rubber particles and asphalt matrix. This leverages the elasticity and toughness of rubber to compensate for the brittleness and plasticity deficiencies of asphalt, achieving synergistic performance optimization. However, with the continuous increase in traffic load and increasingly stringent requirements for road material performance, the aforementioned existing technologies have gradually revealed their inherent limitations and deep-seated contradictions in practical applications. Fundamentally, existing waste tire rubber powder preparation processes, to ensure good dispersion and modification effects in asphalt, often require significant equipment costs, consume high levels of energy, and suffer from low production efficiency. For example, while desulfurization regeneration and fine granulation help improve the activity and compatibility of the rubber powder with asphalt, their complex processes significantly increase production costs, making the final cost of the rubber powder far higher than that of unprocessed raw rubber powder. This severely weakens the economic benefits of waste tire resource utilization, thus limiting its potential for high-volume application in asphalt. This trade-off between economic cost and technological effectiveness constitutes the first deep-seated contradiction currently facing the high-value utilization of waste tires. More critically and challengingly, the inherent limitations of existing technologies become increasingly apparent when attempting to apply these modified rubber powders or traditional polymer modifiers (such as SBS) to specific types of base asphalt, such as Kronen 90 asphalt with high resin content. Kronen 90 asphalt, with its unique chemical composition and rheological properties, exhibits a rapid and significant increase in viscosity after the introduction of conventional modifiers. This abnormal viscosity surge is not a simple, controllable change, but rather a near-uncontrolled system response, causing the modified asphalt to become abnormally viscous, difficult to pump, mix, and pave, severely restricting subsequent construction operations and even rendering the modification process technically infeasible. This phenomenon is not accidental, but rather stems from the complex physicochemical interactions between its high resin content and the added polymers or rubber particles, forming a highly cohesive and difficult-to-process network structure.This inherent material property makes it almost impossible to effectively modify No. 90 asphalt under the existing modification technology framework. Even if modification is barely achieved, the deterioration of its processing performance greatly reduces its application value. Summary of the Invention

[0004] This invention provides a high-content rubber powder composite modified asphalt of No. 90 and its preparation process, aiming to solve key technical problems in existing technologies such as high preparation cost and limited dosage of waste tire rubber powder, and abnormal viscosity surge and severe deterioration of processing performance caused by high rubber content during the modification process of No. 90 base asphalt. This invention achieves high-value utilization of waste resources while significantly improving the road performance and construction convenience of modified asphalt. The high-content rubber powder composite modified asphalt of No. 90 disclosed in this invention is characterized by comprising the following components by mass percentage: 70% to 85% No. 90 base asphalt; 10% to 20% rubber powder; 1.5% to 3% styrene-butadiene-styrene block copolymer (SBS); 3% to 5% viscosity reducer; 1.5% to 2.5% nano-grade calcium carbonate filler; 0.5% to 1.5% coupling agent; and 1.5% to 2.5% saline resin. The total mass of the above components is 100%.

[0005] In a preferred embodiment of the present invention, the refined No. 90 base asphalt has physical properties including a penetration of 80-100 (0.1 mm, 25°C), a softening point of 43-50°C, and a ductility of not less than 100 cm (15°C). The refined No. 90 base asphalt is characterized by a high resin content, with the following mass percentage ranges for saturated components, aromatic components, resin components, and asphaltene: saturated components 5%–10%, aromatic components 40%–50%, resin components 30%–40%, and asphaltene 10%–15%. This unique component characteristic is the fundamental reason for its abnormally high viscosity under the action of conventional modifiers, which the present invention effectively overcomes through subsequent specific processes and synergistic effects of the components.

[0006] In a preferred embodiment of the present invention, the rubber powder is obtained from waste tires through mechanical crushing. The mechanical crushing process includes multi-stage crushing and sieving to ensure that the particle size distribution of the rubber powder meets specific requirements. Specifically, the waste tires are first initially crushed to obtain rubber fragments with a particle size of several millimeters, and then further finely crushed. The fine crushing employs room temperature shear grinding or low-temperature cryogenic crushing technology to maximize the preservation of the polymer structure integrity of the rubber. The crushed rubber powder is sieved through a 40-mesh (425 micrometers) standard test sieve to ensure that all rubber powder particles can pass through the sieve. Coarse particles that do not pass through the 40-mesh sieve are returned to the crushing equipment for further crushing until all of them pass through the sieve. The particle size distribution of the rubber powder has a D90 value (i.e., 90% of the particles are smaller than this value) of less than 425 micrometers, and a D50 value (median particle size) between 150 and 250 micrometers. The bulk density of the rubber powder is 0.4–0.6 g / cm³. 3 The moisture content is less than 0.5%. This type of rubber powder, prepared mechanically, retains more of the characteristics of vulcanized rubber without undergoing desulfurization or other chemical activation treatments. Its cost-effectiveness is significantly better than rubber powder that has undergone deep activation treatment, but its compatibility and dispersibility with asphalt require more stringent process control. This invention, through an innovative preparation process, enables the effective modification and refining of No. 90 asphalt at high dosages.

[0007] In a preferred embodiment of the present invention, the styrene-butadiene-styrene block copolymer (SBS) has a radial or linear structure, a styrene content of 25% to 35%, a melt flow index (MFI, 200℃ / 5kg) of 1 to 5 g / 10 min, and a Mooney viscosity (ML1+4, 100℃) of 40 to 60. The SBS can significantly improve the elasticity and toughness of asphalt, and enhance its low-temperature crack resistance and high-temperature rutting resistance. In the modified asphalt system, SBS swells by absorbing lightweight components from the asphalt, forming a continuous or semi-continuous network structure, thereby imparting elastic characteristics to the asphalt.

[0008] In a preferred embodiment of the present invention, the viscosity reducer is mainly composed of rubber oil or aromatic oil. The viscosity reducer has a flash point of not less than 200°C and a kinematic viscosity (100°C) of 10–50 mmHg. 2 / s, density (15℃) is 0.9~1.0g / cm³ 3The aniline point is 10-50℃. The addition of the rubber oil or aromatic oil is not merely as a simple diluent. Its core function lies in the fact that this viscosity reducer, rich in aromatic hydrocarbon components, has good compatibility with the high content of asphaltenes and gums in 90# asphalt. Introduced in the early stages of the preparation process, the viscosity reducer can preferentially swell and plasticize the heavy components (such as asphaltenes and gums) in the asphalt, thereby interfering with and inhibiting the formation of an excessively dense network structure after the introduction of rubber powder and SBS, thus effectively controlling the abnormal surge in system viscosity at the molecular level. Simultaneously, the viscosity reducer can also promote the swelling and dispersion of rubber powder, improving the interfacial compatibility between rubber powder and the asphalt matrix, thereby improving the ductility and processing performance of the modified asphalt. By reducing the internal friction of the system, it significantly improves the rheological properties of high-solids content (high rubber powder content) mixtures at high temperatures.

[0009] In a preferred embodiment of the present invention, the average particle size (D50) of the nano-sized calcium carbonate filler is 20 to 80 nanometers, and the specific surface area is 15 m². 2 / g to 30m 2 The surface of the modified asphalt is coated with fatty acids (e.g., stearic acid) or silane coupling agents to improve its dispersibility in the organic phase and its interfacial adhesion to asphalt. The introduction of nano-sized calcium carbonate not only improves the adhesion between the modified asphalt and aggregates, thereby enhancing the water stability of the asphalt mixture, but also, due to its nano-sized size and uniform dispersion, can serve as a micro-reinforcing phase, effectively improving the modulus and hardness of the modified asphalt. Simultaneously, it helps stabilize the macroscopic rheological properties of the modified asphalt system by adsorbing lightweight components in the asphalt through its high specific surface area, and may have a favorable structural guiding effect on the formation of the asphalt-polymer network, further synergistically controlling viscosity.

[0010] In a preferred embodiment of the present invention, the coupling agent is mainly composed of an organosilane coupling agent or a titanate coupling agent with dual functional groups of inorganic and organic groups. Preferably, the coupling agent is γ-aminopropyltriethoxysilane or isopropyltris(dodecylbenzenesulfonyl)titanate. The introduction of the coupling agent aims to establish an effective interfacial connection between the rubber powder, nanomaterials and organic polymers such as asphalt and SBS through chemical bonding or physical adsorption. The inorganic groups (such as silanol groups or titanoxy groups) of the coupling agent can react with the hydroxyl groups on the surface of nano-calcium carbonate or the residual active sites on the surface of the rubber powder to form stable chemical bonds; at the same time, its organic groups (such as amino, vinyl, or benzenesulfonyl groups) can physically entangle or chemically crosslink with asphalt molecules or SBS polymer segments, thereby significantly enhancing the interfacial bonding strength between the components and improving the storage stability, anti-segregation ability, and mechanical properties of the composite modified asphalt. It is particularly crucial for mechanically crushed rubber powder with poor dispersibility, effectively promoting its uniform dispersion in the asphalt matrix and inhibiting agglomeration.

[0011] In a preferred embodiment of the present invention, the ionomer resin is mainly composed of ionic polymers of ethylene-(meth)acrylate zinc salt, sodium salt, or lithium salt. The ionomer resin has a melt index (190℃ / 2.16kg) of 0.5–5 g / 10 min and a density of 0.92–0.96 g / cm³. 3 The glass transition temperature is between -10°C and 5°C. The ionic cross-linked structure of the sarin resin endows it with unique physical properties, including excellent toughness, strength, and high-temperature stability. When incorporated into modified asphalt, the sarin resin, by forming a physical network with ionic cross-linking points, can significantly improve the modulus and elasticity of the modified asphalt, thereby enhancing the pavement's rutting resistance and fatigue life. Its dispersion behavior in asphalt forms a complementary reinforcing network with SBS, further improving the overall mechanical properties of the modified asphalt.

[0012] This invention also discloses a preparation process for high-content rubber powder composite modified asphalt No. 90, characterized by the following steps: Step 1, pretreatment and rapid heating of the base asphalt: The modified asphalt No. 90 is added to an asphalt high-temperature tank and slowly heated to 160°C to 170°C, and premixed by mechanical stirring to ensure uniform heating of the asphalt. Subsequently, the temperature of the asphalt is rapidly increased to 195°C to 205°C using a tubular rapid heater and maintained within this temperature range to reduce the initial viscosity of the asphalt, laying a rheological foundation for the efficient mixing of subsequent components. The tubular rapid heater adopts a continuous flow heating mode, and its heating rate is controlled at 5-10°C / second to ensure that the residence time of the asphalt at high temperature is minimized and to avoid aging.

[0013] Step Two, First-Stage Mixing and Strategic Addition: The rapidly heated Kronoswiss 90 base asphalt is introduced into the primary mixer. Under continuous stirring, the viscosity reducer, a portion of the rubber powder (50% to 70% of the total rubber powder), and all the coupling agent are simultaneously or continuously added to the primary mixer in predetermined proportions using a metering feeder. The primary mixer employs an anchor or paddle mixer, with the stirring speed controlled at 100 to 300 rpm and the stirring time at 15 to 30 minutes. This ensures that the viscosity reducer can fully penetrate the Kronoswiss 90 asphalt, effectively swelling the heavy components of the asphalt, while the rubber powder and coupling agent begin to disperse initially. This strategic addition at this stage aims to utilize the synergistic effect of the viscosity reducer and coupling agent to manage the viscosity characteristics of the Kronoswiss 90 asphalt from an early stage, promoting the initial wetting and dispersion of the rubber powder, and creating favorable conditions for subsequent high-intensity mixing.

[0014] Step 3, Second Stage Mixing and Addition of Remaining Components: The mixture obtained in Step 2 is transferred to a two-stage spiral mixer. In this mixer, under stirring conditions, the remaining rubber powder, all SBS, all nano-sized calcium carbonate filler, and all Sarin resin are added sequentially or simultaneously via a metering feeder. The two-stage spiral mixer employs a double-spiral or multi-spiral structure, with the stirring speed controlled at 200 to 400 rpm, the mixing temperature maintained at 190°C to 200°C, and the stirring time at 30 to 60 minutes. The purpose of this stage is to ensure that all polymers (SBS, Sarin resin) and solid fillers (remaining rubber powder, nanomaterials) are fully wetted and initially dispersed in the asphalt matrix. During this stage, the SBS begins to absorb oil and swell, forming a preliminary polymer network.

[0015] Step Four, Third Stage Mixing and Homogenization: The mixture obtained in Step Three is introduced into a three-stage spiral mixer for further homogenization. The three-stage spiral mixer employs a more compact propeller design, increasing the stirring speed to 300-500 rpm, maintaining the mixing temperature at 185°C-195°C, and stirring for 20-40 minutes. This stage, through continuous shearing and mixing, further improves the dispersion uniformity of each component, ensures sufficient polymer swelling, and prepares the system for subsequent high-shear grinding, thereby enhancing the macroscopic homogeneity of the system.

[0016] Step 5, High-Shear Grinding: The mixture obtained in Step 4 is continuously pumped to a shear grinding mill for high-intensity shear treatment. The shear grinding mill is preferably a rotor-stator type high-shear grinding device, with a rotor linear velocity of 20 m / s to 35 m / s and a gap between the stator and rotor controlled at 0.1 mm to 0.5 mm. The mixture needs to undergo single or multiple cycles of shear grinding until the particle size distribution D90 value of the rubber powder in the asphalt is less than 100 micrometers, and the SBS polymer particles are fully dispersed and swollen, forming a uniform network structure. This step promotes the micronization, activation, and depolymerization of the rubber powder by providing strong mechanical shear force, while accelerating the swelling of SBS and its miscibility with the asphalt matrix. This controls the viscosity of the system within a processable range, avoiding the abnormal viscosity surge that occurs in conventional high-shear modification of No. 90 asphalt, achieving the desired development state in a single shearing operation. The temperature during the shear grinding process is controlled at 180℃ to 190℃ to prevent localized overheating.

[0017] Step Six: Fine Dispersion and Stability Enhancement via Colloid Milling: The mixture obtained in Step Five, after high-shear grinding, is continuously pumped to a colloid mill for fine dispersion. The rotor linear velocity of the colloid mill is 25 m / s to 40 m / s, and the grinding gap is controlled between 0.05 mm and 0.2 mm. This step aims to further refine the rubber powder particles, eliminate potential agglomerates, and ensure the uniform distribution and refinement of the SBS polymer network, thereby significantly improving the storage stability, anti-segregation performance, and macroscopic uniformity of the modified asphalt. The temperature during this stage is controlled between 175°C and 185°C. After colloid milling, the viscosity of the modified asphalt should meet the process requirements for pumping and paving.

[0018] Step Seven, Development and Storage: The composite modified asphalt obtained in Step Six is ​​introduced into a sedimentation-resistant rubber asphalt development tank equipped with a low-shear stirring device. It is then continuously stirred at low speed at a temperature of 170℃ to 180℃ for 2.5 to 3.5 hours. During this development process, deeper physicochemical interactions occur between the components, the polymer network structure is further improved, and the compatibility between the rubber powder and asphalt is continuously enhanced. This allows the modified asphalt to reach its optimal performance and effectively prevents the sedimentation and segregation of the rubber powder and nanomaterials, ensuring the uniformity and stability of the final product. After development, the high-content rubber powder composite refined No. 90 modified asphalt can be packaged or used directly in construction.

[0019] The core advantage of the preparation process disclosed in this invention lies in providing a systematic solution to the viscosity problem caused by the high resin content of 90# base asphalt. Specifically, the early introduction and specific proportion of the viscosity reducer, combined with the interfacial activation effect of the coupling agent, effectively pre-treats the asphalt matrix before high-intensity shear grinding, inhibits excessive networking of heavy components, and maintains the system viscosity within a controllable range by promoting the initial swelling and dispersion of the rubber powder, significantly avoiding the viscosity runaway phenomenon in the modification process of 90# asphalt in the prior art. Simultaneously, the combination of multi-stage mixing, high-shear grinding, and fine dispersion by colloid milling provides sufficient mechanical and thermal energy input to the mechanically crushed rubber powder that has not been deeply activated, ensuring that it can achieve sufficient swelling, micronization, and uniform dispersion at high dosages, thereby effectively exerting its modifying effect. The addition of nano-sized calcium carbonate and sarin resin further synergistically improves the overall road performance of the modified asphalt.

[0020] The high-content rubber powder composite modified asphalt prepared by this invention is characterized by: 1. Penetration (0.1 mm, 25℃): between 60 and 80, indicating moderate hardness. 2. Softening point (ring and ball method, ℃): not lower than 65℃, indicating significantly improved high-temperature stability and effective resistance to rutting deformation. 3. Ductility (5 cm / min, 5℃, cm): not less than 20 cm, indicating excellent low-temperature crack resistance. 4. Elastic recovery rate (25℃, %): not less than 80%, indicating significantly improved elastic modulus and fatigue resistance. 5. Segregation (softening point difference, ℃): not greater than 2.5℃, indicating excellent storage stability and effectively overcoming the technical problem of easy segregation in high-content rubber powder asphalt. 6. Brinell rotational viscosity (135℃, mPa·s): not higher than 3000 mPa·s, and Brinell rotational viscosity at 175℃ not higher than 1000 mPa·s, indicating that it has good fluidity and pumpability at construction temperature, fully meeting the requirements of existing construction equipment and processes for modified asphalt viscosity, and completely solving the problem of excessively high viscosity after modification of Kelian No. 90 asphalt, making it difficult to construct.

[0021] In summary, this invention, by constructing a system solution that combines a specific component formulation with an innovative preparation process, not only effectively solves the dual challenges of cost and performance faced by applying high-volume mechanically crushed rubber powder to 90# asphalt, but also fundamentally overcomes the inherent defect of viscosity runaway during the modification process of 90# base asphalt. This provides a novel modified asphalt material and its production method that is environmentally friendly, economically efficient, and has excellent road performance, demonstrating significant industrial application value and social benefits. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the preparation process of the high-content rubber powder composite compound 90 modified asphalt of the present invention. Detailed Implementation

[0023] This invention provides a high-content rubber powder composite modified asphalt No. 90 and its preparation process. This technical solution aims to systematically solve the key technical problems of high cost and limited dosage of waste tire rubber powder in traditional modification processes, and the abnormal viscosity surge of modified No. 90 base asphalt due to its unique component characteristics, which seriously affects its processing performance and construction convenience.

[0024] Through the ingenious synergistic design of component selection, proportioning strategy, and multi-stage preparation process, this invention achieves the effective and high-value utilization of waste resources and significantly improves the road performance and construction adaptability of modified asphalt. In a specific embodiment, the high-content rubber powder composite modified asphalt of No. 90 is characterized by being precisely proportioned by mass percentage of the following components: No. 90 base asphalt 78.0%; rubber powder 15.0%; styrene-butadiene-styrene block copolymer (SBS) 2.0%; viscosity reducer 4.0%; nano-grade calcium carbonate filler 2.0%; coupling agent 0.5%; and sarin resin 0.5%. The total mass ratio of the above components is 100%.

[0025] In a preferred embodiment of the present invention, the Kelian No. 90 base asphalt is obtained by further processing the heavy fraction after atmospheric and vacuum distillation of crude oil through a specific deep processing technology. It exhibits typical physical properties: penetration of 85 (0.1 mm, 25°C), softening point of 46°C, and ductility of not less than 100 cm (15°C). SARA (saturated, aromatic, resinous, and asphaltenes) component analysis of this base asphalt revealed a saturated content of 7.2%, an aromatic content of 44.5%, a resinous content of 35.3%, and an asphaltenes content of 13.0%. This combination of high aromatic and resinous content endows Kelian No. 90 asphalt with excellent ductility and low-temperature performance. However, its high content of resins and asphaltenes makes it prone to forming highly entangled or gel-like network structures when blended with polymer modifiers (such as SBS) or high-content rubber powder, leading to a nonlinear and abnormally rapid increase in system viscosity.

[0026] This invention effectively suppresses this unfavorable rheological behavior by precisely controlling component interactions and process parameters. Furthermore, the rubber powder is derived from a mixture of waste truck tires and passenger car tires, obtained through a refined mechanical crushing process. This process begins with preliminary coarse crushing, breaking down the waste tires into rubber fragments with a particle size of approximately 20 to 50 millimeters.

[0027] Subsequently, these fragments are fed into a multi-stage fine grinding system, including a room-temperature shear mill and a liquid nitrogen-assisted cryogenic grinder, to ensure the required fineness is achieved while maintaining the integrity of the polymer chains. Precise control of the shear rate and freezing temperature minimizes excessive degradation or surface activation of the rubber molecular chains. The ground rubber powder undergoes rigorous particle size separation via a vibrating sieve system, with all particles passing through a standard 40-mesh sieve (425 micrometers aperture). Larger particles that fail to pass are automatically returned to the grinding equipment for further processing until all meet the particle size requirements. The final rubber powder, with a particle size distribution determined by a laser particle size analyzer, has a D90 value (i.e., 90% of the particles are smaller than this value) of 380 micrometers and a D50 value (median particle size) of 210 micrometers.

[0028] Furthermore, the bulk density of the adhesive powder is 0.52 g / cm³. 3 The moisture content is strictly controlled below 0.3%. This type of rubber powder, prepared by a purely mechanical method, retains the intrinsic structure of vulcanized rubber without chemical desulfurization or activation treatment, thus offering a significant cost advantage. However, its surface activity is low, and its compatibility with the asphalt matrix is ​​poor, making it prone to agglomeration and sedimentation, thus posing greater challenges to subsequent preparation processes.

[0029] In a preferred embodiment of the present invention, the styrene-butadiene-styrene block copolymer (SBS) is selected from the radially structured KRATOND1101 type SBS, with a styrene content of 30%, a melt index (MFI, 200℃ / 5kg) of 3.5g / 10min, and a Mooney viscosity (ML1+4, 100℃) of 50. This grade of SBS exhibits good elasticity and a low melting temperature, effectively improving the elastic recovery ability, low-temperature crack resistance, and high-temperature rutting resistance of asphalt. In the modified asphalt system, SBS molecules swell by absorbing the light components (mainly aromatic and partially saturated components) in the asphalt, thereby forming a continuous or semi-continuous three-dimensional physical cross-linked network. The establishment of this network is key to imparting elastic characteristics to the modified asphalt.

[0030] In one specific embodiment, the viscosity reducer is an environmentally friendly rubber oil with a high aromatic content, specifically TDAE (Treated Distillate Aromatic Extract). This viscosity reducer has a flash point of 220°C and a kinematic viscosity (100°C) of 35 mmHg. 2 / s, density (15℃) is 0.98g / cm³ 3The aniline point is 35°C. The core function of this viscosity reducer is not simple dilution, but rather its excellent compatibility with the high content of resin powder and asphaltenes in 90# asphalt. The viscosity reducer is strategically introduced in the early stages of the preparation process, allowing it to preferentially and deeply penetrate and swell the heavy components in the asphalt. This pre-swelling effect effectively interferes with and weakens the excessively dense, high-viscosity network structure formed by these heavy components after the subsequent introduction of rubber powder and SBS. By pre-"plasticizing" the asphalt matrix at the molecular level, the viscosity reducer fundamentally inhibits abnormal spikes in system viscosity.

[0031] At the same time, it also significantly promotes the wetting and swelling of the rubber powder particles, reduces the interfacial tension between the rubber powder and the asphalt matrix, thereby improving the dispersion uniformity and compatibility of the rubber powder, and ultimately improving the processing rheological properties and ductility of high-content rubber powder composite modified asphalt.

[0032] Furthermore, the average particle size (D50) of the nano-sized calcium carbonate filler is 50 nanometers, and the specific surface area is 22 m². 2 / g, its surface is modified by hydrophobic coating with stearic acid. This surface treatment enhances the dispersibility of nano-calcium carbonate in the organic phase and its interfacial adhesion with the asphalt matrix. The introduction of nano-calcium carbonate has multiple functions: firstly, as a highly efficient filler, it can significantly improve the adhesion between modified asphalt and aggregates, thereby improving the water stability of asphalt mixtures and reducing water damage.

[0033] Secondly, due to its nanoscale size and uniform dispersion in the asphalt matrix, it acts as a micro-reinforcing phase, effectively improving the modulus and hardness of modified asphalt and enhancing its resistance to rutting deformation. Furthermore, its high specific surface area allows it to adsorb some of the lightweight components in the asphalt, contributing to the stabilization of the macroscopic rheological properties of the modified asphalt system. Through its interfacial activity, it also plays a beneficial guiding role in the formation and structural improvement of the SBS polymer network, thus contributing positively to the synergistic control of the system viscosity.

[0034] In a preferred embodiment of the present invention, the coupling agent is γ-aminopropyltriethoxysilane (KH-550). This coupling agent's molecular structure contains an amino group (organophilic group) and a triethoxysilyl group (inorganophilic group). Its inorganic-philic group, upon hydrolysis, can generate silanol, which can chemically bond with the hydroxyl groups on the surface of nano-calcium carbonate or the residual active functional groups on the surface of the rubber powder. Simultaneously, its amino functional group can establish interfacial connections with polar components in asphalt molecules or SBS polymer segments through physical entanglement or chemical cross-linking. Through this bidirectional chemical bridging effect, the coupling agent significantly enhances the interfacial bonding strength between solid particles such as rubber powder and nano-calcium carbonate and organic polymers such as asphalt and SBS. This is crucial for improving the storage stability, anti-segregation ability, and macroscopic mechanical properties of composite modified asphalt. Especially for mechanically crushed rubber powder that has not been deeply activated, the coupling agent can effectively promote its uniform dispersion in the asphalt matrix and inhibit its agglomeration behavior.

[0035] In one specific embodiment, the Ionomer resin used is DuPont Surlyn 8940, whose main component is ethylene-zinc methacrylate. This Ionomer resin has a melt index (190℃ / 2.16kg) of 1.8g / 10min and a density of 0.94g / cm³. 3 The glass transition temperature is approximately 0°C. The unique ionic cross-linking structure of sarin resin endows it with excellent toughness, strength, and high-temperature stability. When incorporated into modified asphalt, the sarin resin forms a physical network with dynamic ionic cross-linking points within the asphalt matrix. This network complements and synergistically enhances the elastic network formed by SBS, significantly improving the shear modulus and elasticity of the modified asphalt, thereby strengthening the overall rutting resistance and fatigue life of the pavement. The addition of sarin resin provides additional mechanical property enhancements to high-content rubber-powder composite modified asphalt, especially in terms of performance stability under extreme temperatures.

[0036] The present invention also discloses a preparation process for high-content rubber powder composite 90 modified asphalt, characterized by systematically overcoming the challenge of blending high-content rubber powder with high-resin content matrix asphalt through a series of precisely controlled stage operations.

[0037] Please refer to Figure 1First, in step one, the pretreatment and rapid heating of the base asphalt. 78.0% of the refined No. 90 base asphalt is precisely metered and added to a high-temperature asphalt tank equipped with a high-efficiency heat exchanger. The tank is equipped with a low-speed anchor mixer to ensure uniform heating of the asphalt. The asphalt is slowly heated to 165°C and premixed for approximately 10 minutes. Subsequently, the asphalt is continuously pumped into a specially designed tubular rapid heater. This heater employs a unique serpentine tube bundle structure and a high heat flux design, enabling it to rapidly raise the asphalt temperature from 165°C to 200°C in a very short time (typically less than 30 seconds), with the heating rate strictly controlled at 8°C / second. The purpose of this rapid heating is to ensure that the asphalt reaches the required reaction temperature while minimizing its residence time at high temperatures, thereby effectively inhibiting thermal aging of the asphalt and maintaining its original physicochemical properties. Throughout the rapid heating and transportation process, the asphalt temperature is maintained within the range of 195°C to 205°C to significantly reduce the initial viscosity of the asphalt, laying a good rheological foundation for the efficient wetting and dispersion of subsequent solid components. Secondly, step two, the first stage of mixing and strategic addition.

[0038] The rapidly heated asphalt obtained in step one is continuously fed into a primary mixer. This mixer is equipped with a paddle agitator with a baffle plate, and the mixing speed is set to 200 rpm. Under continuous mixing, 4.0% of the viscosity reducer (TDAE), 70% of the rubber powder (accounting for 15.0% of the total rubber powder), i.e., 10.5% of the rubber powder, and all of the 0.5% coupling agent (KH-550) are continuously and synchronously injected into the primary mixer through their respective independent inlets in a predetermined ratio using a high-precision metering feeding device. The mixing time in this stage is controlled to be 20 minutes.

[0039] The strategic aspect of this stage lies in the early and simultaneous introduction of viscosity reducers and coupling agents. The abundant aromatic components in the viscosity reducers preferentially penetrate and swell to overcome the high resin and asphaltenes content in No. 90 asphalt, thus pre-treating the asphalt matrix at a physical level. This effectively inhibits the formation of an over-crosslinked network structure during subsequent high-intensity mixing, controlling the viscosity surge from the source. Simultaneously, the addition of coupling agents rapidly promotes the wetting and dispersion of rubber powder particles in the initial stage, reducing the interfacial tension between the rubber powder and asphalt, creating favorable conditions for the subsequent full swelling and uniform distribution of the rubber powder.

[0040] This stage of mixing ensures the initial uniform distribution of the components and interface activation. Next, step three, the second stage mixing, involves the addition of the remaining components. The mixture obtained in step two is pumped via pipeline to a two-stage spiral mixer. This mixer employs a double-spiral structure design, possessing excellent axial and radial mixing capabilities, with a stirring speed set at 300 rpm and a mixing temperature precisely maintained at 195°C. In this mixer, the remaining 30% of the rubber powder (i.e., 4.5% rubber powder), all of the 2.0% SBS (KRATOND1101), all of the 2.0% nano-sized calcium carbonate filler, and all of the 0.5% Suryn resin (Surlyn8940) are added sequentially or simultaneously via another metering system. The mixing time for this stage is 45 minutes. The purpose of this stage is to ensure that all polymers (SBS, Suryn resin) and the remaining solid fillers (rubber powder, nano-calcium carbonate) are adequately wetted and initially dispersed in the pretreated asphalt matrix. In this stage, SBS begins to absorb the lightweight components in the asphalt and slowly swells, gradually forming a preliminary polymer network. Sarin resin also begins to soften and disperse at high temperatures. Nano-calcium carbonate, through the action of a coupling agent, further enhances its bonding with the asphalt matrix. Next, in step four, the third stage of mixing and homogenization, the mixture obtained in step three is continuously pumped to a three-stage spiral mixer. This mixer is equipped with more compact propeller blades, providing a higher shear rate and stronger mixing intensity. The stirring speed is further increased to 400 rpm, and the mixing temperature is maintained at 190°C. The stirring time for this stage is set to 30 minutes. Through continuous shearing and mixing, the main goal of this stage is to further improve the dispersion uniformity of the components, ensure sufficient swelling of the polymers (SBS and Sarin resin), and promote the formation of a more complete macroscopically homogeneous system in the asphalt matrix. This homogenization treatment is crucial for improving the efficiency of subsequent high-shear grinding and product quality. Further, in step five, high-shear grinding...

[0041] The homogeneous mixture obtained in step four is continuously pumped to a rotor-stator high-shear mill. This mill has high energy input characteristics, with a rotor linear velocity set at 28 m / s and the gap between the stator and rotor precisely controlled at 0.2 mm. The mixture undergoes multiple cycles of shear milling, typically 3 to 5 times, with the flow rate and time of each cycle optimized. High-shear milling is one of the core steps in the process of this invention. It provides strong mechanical shear force to refine, deagglomerate, and activate the powder particles, ultimately reducing their particle size distribution D90 value to less than 90 micrometers.

[0042] Simultaneously, high shear force significantly accelerates the swelling of SBS polymer in asphalt and its miscibility with the asphalt matrix, promoting the formation of a fine and uniform continuous network structure of SBS. This step effectively controls the abnormal viscosity surge that may occur during the modification of No. 90 asphalt due to high resin content, keeping the system viscosity within a pumpable and workable range. The temperature during the grinding process is precisely controlled at 185℃ to avoid localized overheating that could adversely affect the properties of the asphalt and polymer. Furthermore, step six, fine dispersion and enhanced stability through colloid milling.

[0043] The high-shear grinding mixture obtained in step five is continuously pumped to a high-performance colloid mill for fine dispersion. The rotor linear velocity of the colloid mill is set to 32 m / s, and the grinding gap is precisely controlled at 0.1 mm. The main objective of this step is to further refine the rubber powder particles, eliminate any remaining micro-agglomerates, and ensure the uniform distribution and refinement of the SBS polymer network. The extreme shear force provided by the colloid mill significantly improves the storage stability, anti-segregation properties, and macroscopic uniformity of the modified asphalt, ensuring long-term product performance stability. The temperature during this stage is controlled at 180°C. After colloid milling, the viscosity of the modified asphalt reaches a level that meets the requirements of existing pumping, storage, and paving construction processes.

[0044] Finally, step seven, development and storage. The composite modified asphalt obtained in step six is ​​poured into a sedimentation-resistant rubber asphalt development tank equipped with a low-shear agitator. Development is carried out at 175°C with continuous stirring at a low speed of 50 rpm for 3.0 hours. During this development process, deeper physicochemical interactions occur between the components, particularly the polymer network structure of SBS and sarin resin is further improved and stabilized, and the compatibility between rubber powder and asphalt is continuously enhanced. This low-speed stirring also effectively prevents sedimentation and segregation of rubber powder and nanomaterials during long-term storage, ensuring the homogeneity and long-term storage stability of the final product. After development, the high-content rubber powder composite 90# modified asphalt can be packaged or directly used in subsequent asphalt mixture production and construction. The high-content rubber powder composite 90# modified asphalt prepared by this invention exhibits excellent road performance and processing adaptability after various performance index tests.

[0045] 1) Asphalt performance study The properties of conventionally briquette-refined No. 90 asphalt and blended briquette-refined No. 90 asphalt with different rubber powder contents were studied. The properties of conventionally briquette-refined No. 90 asphalt and blended briquette-refined No. 90 asphalt with different rubber powder contents are shown in Table 1 and Table 2, respectively.

[0046] Table 1. Performance of conventionally compounded No. 90 asphalt under different rubber powder content conditions.

[0047] Table 2. Performance of Blended No. 90 Asphalt under Different Rubber Powder Content Conditions

[0048] 2) Properties of asphalt mixtures The results of the comparison of low-temperature performance between conventional asphalt mixtures and asphalt mixtures modified with high rubber powder content are shown in Table 3.

[0049] Table 3. Traditional asphalt mixtures and asphalt mixtures modified with high rubber powder content

[0050] Compared to SMA-13, ARHM-13 exhibited a 7.95℃ decrease in fracture temperature, representing a 29.0% reduction, indicating that the high-content rubber-asphalt mixture demonstrated better low-temperature performance. The freeze-thaw strength, characterizing the maximum stress the mixture could withstand during low-temperature shrinkage, also showed a significant improvement. ARHM-13 showed a 2.46MPa increase in fracture strength compared to the discontinuously graded SMA-13, representing a 69.5% increase. The inflection point temperature and the rate of increase in temperature stress reflected the changes in the rheological properties of the material system during temperature decrease, i.e., the occurrence of the ductile-brittle transition. Specifically, compared to SMA-13, ARHM-13 showed a 7.76℃ decrease in inflection point temperature, representing a 36.0% reduction, and an increase of 0.076 in the slope of the relaxation stage temperature stress curve, representing a 35.3% increase. In summary, the addition of rubber powder significantly delayed the ductile-brittle transition process by mitigating crack initiation and hindering crack propagation, thereby effectively improving the low-temperature performance of the system.

[0051] The high-temperature rutting resistance of conventional modified asphalt mixtures and high-content rubber powder modified asphalt mixtures is shown in Table 4.

[0052] Table 4. Comparison of High-Temperature Rutting Resistance between Conventional Modified Asphalt Mixture and High-Concentration Rubber Powder Modified Asphalt Mixture

[0053] The data comparison above clearly demonstrates that this invention, through the synergistic effect of a specific component formulation and innovative preparation process, not only effectively solves the dual challenges of cost and performance faced by applying high-volume mechanically crushed rubber powder to No. 90 asphalt, but also fundamentally overcomes the inherent defect of viscosity runaway during the modification process of No. 90 base asphalt. It successfully controls the construction viscosity of the modified asphalt within a reasonable range, ensuring good workability. The resulting modified asphalt possesses excellent penetration, softening point, ductility, elastic recovery rate, and storage stability, significantly improving its overall road performance. It fully meets or even exceeds the stringent requirements of modern high-grade highways for asphalt materials, demonstrating significant industrial application value and social benefits.

Claims

1. A high-content rubber powder composite compound 90# modified asphalt, characterized in that, Composed of the following components by mass percentage: Refining No. 90 base asphalt to 70%-85%; 10%-20% adhesive powder; Styrene-butadiene-styrene block copolymer 1.5%-3%; Viscosity reducer 3%-5%; Nano-grade calcium carbonate filler material: 1.5%-2.5%; Coupling agent 0.5%-1.5%; Sarin resin 1.5%-2.5%; The total mass of all components is 100%.

2. The high-content rubber powder composite refined No. 90 modified asphalt according to claim 1, characterized in that: The penetration of the refined No. 90 base bitumen is 80-100, the softening point is 43-50℃, and the ductility is ≥100cm. The mass percentage content ranges of the saturated content, aromatic content, resin content, and asphaltene in the refined No. 90 base bitumen are as follows: saturated content 5%-10%, aromatic content 40%-50%, resin content 30%-40%, and asphaltene 10%-15%. The rubber powder is obtained from waste tires through a multi-stage crushing and screening process using mechanical crushing. Its particle size distribution has a D90 value < 425 micrometers, a D50 value between 150-250 micrometers, and a bulk density of 0.4-0.6 g / cm³. 3 Moisture content <0.5%.

3. The high-content rubber powder composite refined No. 90 modified asphalt according to claim 1, characterized in that: The styrene-butadiene-styrene block copolymer has a radial or linear structure, a styrene content of 25%-35%, a melt index of 1-5 g / 10 min, and a Mooney viscosity of 40-60. The viscosity reducer is mainly composed of rubber oil or aromatic oil, with a flash point ≥200℃ and a kinematic viscosity of 10-50 mmHg. 2 / s, density is 0.9-1.0 g / cm³ 3 The aniline point is 10-50℃. The viscosity reducer is rich in aromatic hydrocarbon components, which have good compatibility with the high content of gum and asphaltenes in the No. 90 asphalt.

4. The high-content rubber powder composite refined No. 90 modified asphalt according to claim 1, characterized in that: The nanoscale calcium carbonate filler has an average particle size of 20-80 nanometers and a specific surface area of ​​15-30 m². 2 / g, the surface of which is coated and modified with fatty acid or silane coupling agent; the main component of the silane coupling agent is an organosilane coupling agent or titanate coupling agent with dual functional groups of inorganic and organic groups, preferably γ-aminopropyltriethoxysilane or isopropyltrititanate.

5. The high-content rubber powder composite refined No. 90 modified asphalt according to claim 1, characterized in that: The sarin resin is mainly composed of ionic polymers of ethylene-(meth)acrylate zinc salt, sodium salt, or lithium salt, with a melt index of 0.5-5 g / 10 min and a density of 0.92-0.96 g / cm³. 3 The glass transition temperature is between -10°C and 5°C, and the sarin resin forms a physical network with ionic crosslinking points.

6. A preparation process for high-content rubber powder composite calendered No. 90 modified asphalt, applied to the high-content rubber powder composite calendered No. 90 modified asphalt according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Pretreatment and rapid heating of the base asphalt; Step Two: Phase One Mixing and Strategic Addition; Step 3: Second stage mixing and addition of remaining components; Step 4, the third stage of mixing and homogenization; Step 5: High-shear grinding; Step 6: Fine dispersion and enhanced stability through colloid milling; Step 7: Development and Storage.

7. The preparation process according to claim 6, characterized in that: Step one includes: heating the No. 90 matrix asphalt to 160-170°C and premixing it by mechanical stirring, then rapidly raising the temperature of the asphalt to 195-205°C by a tubular rapid heater and maintaining this temperature range, with the heating rate of the tubular rapid heater controlled at 5-10°C / second. Step two includes: introducing the heated No. 90 base asphalt into a primary mixer, and adding the viscosity reducer, some rubber powder and all coupling agent into the primary mixer in a predetermined ratio under continuous stirring. The primary mixer adopts an anchor or paddle mixer, the stirring speed is controlled at 100-300 rpm, and the stirring time is 15-30 minutes.

8. The preparation process according to claim 7, characterized in that: Step three includes: transferring the mixture obtained in step two to a two-stage spiral mixer, and adding the remaining adhesive powder, all SBS, all nano-sized calcium carbonate filler, and all Sarin resin under stirring conditions. The two-stage spiral mixer adopts a double spiral or multi-spiral structure, the stirring speed is controlled at 200-400 rpm, the mixing temperature is maintained at 190-200℃, and the stirring time is 30-60 minutes. Step four includes: introducing the mixture obtained in step three into a three-stage spiral mixer, with a stirring speed of 300-500 rpm, a mixing temperature of 185-195℃, and a stirring time of 20-40 minutes.

9. The preparation process according to claim 8, characterized in that: Step five includes: continuously pumping the mixture obtained in step four to a rotor-stator high-shear grinding equipment for shearing treatment. The rotor linear speed is 20-35 m / s, and the gap between the stator and the rotor is controlled at 0.1-0.5 mm. The mixture needs to undergo single or multiple cycles of shearing and grinding until the particle size distribution D90 value of the rubber powder particles in the asphalt is <100 micrometers. The temperature during the shearing and grinding process is controlled at 180-190℃. Step six includes: continuously pumping the mixture obtained in step five to a colloid mill for fine dispersion treatment, wherein the rotor linear velocity of the colloid mill is 25-40 m / s, the grinding gap is controlled at 0.05-0.2 mm, and the temperature of the colloid mill treatment stage is controlled at 175-185℃.

10. The preparation process according to claim 9, characterized in that: Step seven includes: pouring the composite modified asphalt obtained in step six into a sedimentation-resistant rubber asphalt development tank equipped with a low-shear stirring device, and continuously stirring and developing it at a low speed at a temperature of 170-180℃ for 2.5 to 3.5 hours. The high-content rubber powder composite refined No. 90 modified asphalt prepared by the above preparation process has a penetration of 60-80, a softening point ≥65℃, a ductility ≥20cm, an elastic recovery rate ≥80%, a segregation ≤2.5℃, a Brookfield rotational viscosity ≤3000mPa·s, and a Brookfield rotational viscosity at 175℃ ≤1000mPa·s.

Images