High viscosity emulsified asphalt and method for preparing the same

Abstract

The application belongs to the technical field of road engineering materials, and particularly discloses high-viscosity emulsified asphalt and a preparation method thereof, which comprises the following steps: S1, adjusting the pH of part of deionized water to 2-3, adding part of a composite emulsifier and a stabilizer, and stirring until completely dissolved to obtain an acidic soap solution; S2, adjusting the pH of the remaining deionized water to 9-10, adding an amino-terminated hyperbranched polyamide, an amino-terminated liquid butadiene-acrylonitrile and epoxy-modified nano silicon dioxide, and obtaining an alkaline activation solution after high-speed dispersion; S3, after heating base asphalt, pouring the base asphalt into the acidic soap solution, and obtaining initial emulsion through colloid mill shearing emulsification; S4, after cooling the initial emulsion, adding the alkaline activation solution, the remaining composite emulsifier and an epoxy resin emulsion in sequence under stirring, continuing to stir, cooling to room temperature, and filtering, and the high-viscosity emulsified asphalt is obtained.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, specifically relating to a high-viscosity emulsified asphalt and its preparation method. Background Technology

[0002] Emulsified asphalt, a key road construction material in the field of road engineering, is widely used in highway construction, preventive maintenance, and bridge deck waterproofing tack coats due to its energy-saving and carbon-reducing advantages brought about by its normal-temperature construction characteristics, as well as its excellent aggregate coating ability. In recent years, with the increasing demands for interlayer shear strength in high-grade highway asphalt pavement wearing courses, steep longitudinal slope sections, and bridge deck paving, the need for high-viscosity modified emulsified asphalt has become increasingly urgent. High-viscosity emulsified asphalt can significantly enhance the adhesion between asphalt and aggregates, improving the pavement's resistance to rutting and shoving, and has become a hot research topic in the industry.

[0003] Currently, the mainstream technical approaches to achieving high viscosity in emulsified asphalt can be divided into two categories: one is physical blending modification based on polymer latex, and the other is in-situ thickening modification based on chemical crosslinking. The former is represented by linear polymer latexes such as SBS (styrene-butadiene-styrene block copolymer) and SBR (styrene-butadiene rubber), which are dispersed in the asphalt emulsion system under high shear and utilize polymer network entanglement to increase viscosity; the latter introduces crosslinking agents to promote chemical reactions between the polymer and the active components of asphalt, constructing a three-dimensional network structure.

[0004] Chinese patent application CN116355584A discloses a novel high-viscosity modified emulsified asphalt bridge deck waterproof bonding material and its preparation method. The technical solution is as follows: the high-viscosity modified emulsified asphalt comprises, by weight, 50-65 parts base asphalt, 1-3 parts SBS latex, 2-3 parts SBR latex, 1-3 parts CR latex, 3-4 parts emulsifier, 0.5-0.7 parts stabilizer, 0.8-1.0 parts acidity regulator, 0.02-0.03 parts Class A additives, 0.1-0.3 parts Class B additives, and 30-35 parts water. The preparation method employs a "two-stage thermal mixing method" and a "two-stage crosslinking reaction" process: First, SBS latex, SBR latex, CR latex, and Class A additives (zinc oxide / magnesium oxide crosslinking agent + ethylidene thiourea accelerator) are added to the base soap solution and subjected to high-speed shearing to ensure thorough mixing and crosslinking of the latex modifiers, resulting in a composite soap solution; then, the composite soap solution is emulsified with the hot matrix asphalt through a colloid mill to obtain Class A modified emulsified asphalt; finally, Class B additives (organic peroxide crosslinking agent 2,4-dichlorobenzoyl peroxide + triallyl isocyanurate accelerator) are added to the Class A modified emulsified asphalt and subjected to high-speed shearing again, resulting in a second crosslinking reaction that allows the latex and matrix asphalt to form a stable network structure. This scheme uses SBS, SBR, and CR latexes for composite modification and two cross-linking reactions to achieve a balance between viscosity and stability in emulsified asphalt. However, firstly, the SBS, SBR, and CR used are all linear polymer latexes, which have inherently limited compatibility with asphalt, requiring high shear force dispersion. Furthermore, the physical cross-linking network formed is prone to dissociation at high temperatures, resulting in a significant reduction in viscosity contribution at high temperatures. Secondly, the secondary cross-linking reaction mainly occurs after emulsification, and the cross-linking network is mainly formed outside the asphalt particles or in the aqueous phase. This makes it difficult to effectively overcome the gravity sedimentation caused by the density difference between polymers and asphalt particles during storage, easily leading to phase separation and limited improvement in storage stability. In addition, although linear polymers can improve high-temperature performance, their molecular chains tend to harden and become brittle at low temperatures, resulting in insufficient improvement in the low-temperature crack resistance of the material, making it difficult to meet the stringent requirements for both high and low temperature performance of pavement materials in extremely cold regions. Summary of the Invention

[0005] To address the problems of poor high-viscosity emulsified asphalt performance at both high and low temperatures and poor storage stability in existing technologies, this invention aims to provide a high-viscosity emulsified asphalt and its preparation method. Through time-series and pH control, terminal amino-terminated hyperbranched polyamide, terminal amino-terminated liquid butadiene-acrylonitrile, epoxy-modified nano-silica, and epoxy resin emulsion are in situ and directionally anchored on the surface of asphalt particles. This effectively avoids the phase separation, component agglomeration, and demulsification problems caused by traditional simple blending, thus improving the storage stability of the emulsified asphalt. Simultaneously, the cross-linked network synergistically constructed by the modified components enables the product to possess both high viscosity and good high and low temperature performance, making it suitable for various complex engineering scenarios.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing high-viscosity emulsified asphalt includes the following steps: S1. Preparation of acidic soap solution: Heat part of the deionized water to 40-50℃, adjust the pH to 2-3, add part of the composite emulsifier and stabilizer, stir until completely dissolved, and obtain acidic soap solution; S2. Preparation of alkaline activation solution: Heat the remaining deionized water to 55-65℃, adjust the pH to 9-10, add amino-terminated hyperbranched polyamide, amino-terminated liquid butadiene-acrylonitrile and epoxy-modified nano silica, and disperse at high speed at 2000-3000r / min for 20-30min to obtain alkaline activation solution. S3. Primary emulsification: After heating the base asphalt to 150℃-170℃, pour it into the acidic soap solution from step S1, and shear emulsify it for 3-5 minutes using a colloid mill at a speed of 2500-3500r / min to obtain the primary emulsion. S4. Secondary compounding: Cool the primary emulsion from step S3 to 50-55℃, and add the alkaline activating liquid from step S2, the remaining compound emulsifier, and the epoxy resin emulsion in sequence while stirring. Continue stirring for 10-15 minutes, then quickly cool to room temperature and filter to obtain high-viscosity emulsified asphalt.

[0007] In this scheme, acidic soap solution and alkaline activating solution are prepared in steps to control the timing of emulsification and modification reactions. First, the asphalt base emulsification is completed to form a stable primary emulsion. Then, the interface reaction is triggered by acid-base neutralization, so that the modified components can be quickly adsorbed and bonded on the surface of asphalt particles to form an organic-inorganic interface layer. This constructs a core-shell structure with the asphalt matrix as the core and the organic-inorganic hybrid layer as the shell, which effectively avoids the problems of phase separation, component agglomeration and demulsification caused by traditional simple blending. When an alkaline activating solution is added to an acidic pre-emulsion, the local pH is instantly neutralized, forming a "pH-responsive interfacial self-assembly" process. The core of this process lies in the fact that the addition of the alkaline activating solution instantly neutralizes the acidic environment of the pre-emulsion. On one hand, this activates the reactivity of the terminal amino-terminated hyperbranched polyamide, enabling it to bond with the asphalt surface groups. On the other hand, the change in pH also regulates the charge state of each component's surface, enhancing the electrostatic adsorption between the negatively charged epoxy-modified nano-silica and the positively charged asphalt particles. This drives the modified components to spontaneously and orderly arrange themselves on the particle surface, forming an organic-inorganic hybrid interfacial layer. Simultaneously, the epoxy resin emulsion is uniformly dispersed and adsorbed on the asphalt particle interface, forming an "interfacial active pairing" with the pre-anchored amino components, precisely laying the groundwork for efficient crosslinking after demulsification during construction. This ensures that the synergistic crosslinking network is uniformly and stably constructed around and between asphalt particles, rather than forming local clusters, guaranteeing that each component can fully function and maximize performance.

[0008] Preferably, the stirring speed in step S1 is 150-250 r / min.

[0009] Preferably, the feeding rate of hot asphalt added to the acidic soap solution in step S3 is 2.5-3.3 kg / min.

[0010] Preferably, the stirring speed in step S4 is 400-600 r / min.

[0011] The present invention also provides a high-viscosity emulsified asphalt prepared by the above method.

[0012] Preferably, the high-viscosity emulsified asphalt comprises the following raw materials in parts by weight: 100 parts base asphalt; 3.0-5.0 parts composite emulsifier; 3-5 parts amino-terminated hyperbranched polyamide; 1.5-2.5 parts amino-terminated liquid butadiene-acrylonitrile; 0.8-1.2 parts epoxy-modified nano silica; 2-4 parts epoxy resin emulsion; 0.1-0.3 parts stabilizer; and 45-55 parts water.

[0013] In this scheme, a synergistic crosslinking network is constructed through the synergistic effect of amino-terminated hyperbranched polyamide, amino-terminated liquid butadiene-acrylonitrile, epoxy-modified nano-silica, and epoxy resin emulsion, which solves the technical problem of the difficulty in achieving both high and low temperature performance of traditional high-viscosity emulsified asphalt.

[0014] Low-dosage end-amino hyperbranched polyamides and epoxy resin emulsions work together to form a dense three-dimensional chemical cross-linked network, serving as the rigid skeleton of the asphalt system. This significantly improves the high-temperature viscosity and softening point of the emulsified asphalt. Simultaneously, the end-amino liquid butadiene-acrylonitrile, with its flexible chains, embeds itself into this rigid network, relieving internal stress and resolving the contradiction of "excessive rigidity leading to brittleness" in high-viscosity asphalt. Furthermore, it optimizes the interfacial compatibility of each component, preventing component delamination. The epoxy groups on the surface of epoxy-modified nano-silica can simultaneously participate in the cross-linking of the organic network, firmly anchoring inorganic nanoparticles in the organic matrix to form an organic-inorganic hybrid structure. This structure acts as a stress transfer hub, dispersing locally concentrated stress into the three-dimensional network. This not only alleviates the internal stress concentration of the rigid skeleton but also activates the toughening mechanism of the flexible chain segments. Thus, with low dosage, it simultaneously achieves cross-scale performance improvements in high viscosity, high softening point, and high and low temperature ductility.

[0015] Preferably, the terminal amino hyperbranched polyamide has a molecular weight of 1900-2200 and an amino functionality of 12-16.

[0016] In this scheme, the molecular weight and amino range ensure that the terminal amino groups have sufficient reactivity, enabling them to efficiently chemically bond with the acidic components of asphalt (carboxyl groups, phenolic hydroxyl groups, etc.) during the demulsification process, while forming an appropriate crosslinking density. This ensures both the viscosity improvement effect and avoids excessive crosslinking that could lead to increased brittleness of the system.

[0017] Preferably, the preparation method of the epoxy-modified nano-silica includes the following steps: Tetraethyl orthosilicate and epoxy silane coupling agent are dispersed in an aqueous ethanol solution, stirred until homogeneous, the pH of the system is adjusted to 9-10, the temperature is raised to 60-80℃, and the reaction is stirred for 4-6 hours. The product is then separated, washed, vacuum dried, and ground to obtain the final product.

[0018] In this scheme, epoxy-modified nano-silica is prepared by sol-gel in-situ co-condensation, so that epoxy groups are uniformly distributed on the surface and near-surface layer of nanoparticles, laying the microstructure foundation for the storage stability and high viscosity of high-viscosity emulsified asphalt.

[0019] Preferably, the epoxy silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0020] Preferably, the mass ratio of the tetraethyl orthosilicate, γ-glycidoxypropyltrimethoxysilane, and the aqueous ethanol solution is 2-4:1:10.

[0021] Preferably, the composite emulsifier is composed of hexadecyltrimethylammonium bromide, alkyl polysaccharide and ligninamine.

[0022] Preferably, the mass ratio of hexadecyltrimethylammonium bromide, alkyl polysaccharide and ligninamine is 2:0.9-1.1:0.9-1.1.

[0023] In this scheme, the compound emulsification system can simultaneously and efficiently emulsify matrix asphalt, amino-terminated hyperbranched polyamide, amino-terminated liquid butadiene-acrylonitrile, and epoxy-modified nano-silica through the multi-component charge synergy effect and steric hindrance effect, forming a stable and uniform multiphase suspension system.

[0024] Preferably, the epoxy resin emulsion is an aqueous epoxy resin emulsion.

[0025] Preferably, the solid content of the aqueous epoxy resin emulsion is 50%-54%, and the epoxy equivalent is 450-550 g / eq.

[0026] Preferably, the stabilizer is obtained by compounding ammonium chloride and polyvinyl alcohol.

[0027] Preferably, the degree of polymerization of the polyvinyl alcohol is 1700-1800.

[0028] Preferably, the mass ratio of ammonium chloride to polyvinyl alcohol is 0.9-1.1:1.

[0029] In this scheme, ammonium chloride, as an electrolyte stabilizer, can adjust the thickness of the electric double layer of the emulsion and enhance the electrostatic repulsion between asphalt particles; polyvinyl alcohol, as a high molecular protective colloid, prevents particle aggregation through steric hindrance; the synergistic effect of the two further improves the overall stability of the emulsion.

[0030] Compared with the prior art, the beneficial effects of the present invention are: The method for preparing high-viscosity emulsified asphalt in this invention utilizes electrostatic adsorption and bonding through time-series and pH control to form an organic-inorganic interface layer. This constructs a core-shell structure with the asphalt matrix as the core and the organic-inorganic hybrid layer as the shell, effectively avoiding the problems of phase separation, component agglomeration, and demulsification caused by traditional simple blending. Furthermore, it achieves in-situ, directional anchoring of modified components on the surface of asphalt particles, ensuring that the cross-linked network constructed by the modified components can truly be established around and between the asphalt particles, thereby achieving optimal performance.

[0031] This invention modifies the base asphalt by using a specific ratio of terminal amino hyperbranched polyamide, terminal amino liquid butadiene-acrylonitrile, epoxy-modified nano silica, and epoxy resin emulsion to construct a synergistic crosslinking network. This results in an emulsified asphalt with a 5-day storage stability of <3%, an evaporation residue dynamic viscosity of 54673-58168 Pa·s at 60°C, a softening point >90°C, and a ductility of >30 cm at 5°C. This invention solves the technical problems of traditional high-viscosity emulsified asphalt, such as the contradiction between viscosity and workability, difficulty in balancing high and low temperature performance, poor storage stability, and easy component stripping. Detailed Implementation

[0032] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0033] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available.

[0034] Base asphalt: 70# road petroleum asphalt, conforming to GB / T15180-2017 standard; Alkyl glycoside produced by Yixing Jinlan Chemical Co., Ltd., model APG0810; Lignin amine produced by Jinan Shengquan Group Co., Ltd., model SOBIOL-1P; Amino-terminated hyperbranched polyamide produced by Wuhan Hyperbranched Resin Co., Ltd., model HyPerN103; molecular weight 1900-2200, amino functionality 12-16; Amino-terminated liquid butadiene-acrylonitrile (ATBN): number average molecular weight 2000-3000, amino-terminated content 0.3-0.6mmol / g, butadiene segment proportion 70%-80%; Waterborne epoxy resin emulsion produced by Shanghai Huayi Chemical Co., Ltd., model STW602, solid content 50%-54%, epoxy equivalent 450-550g / eq; Polyvinyl alcohol produced by Anhui Wanwei Group Co., Ltd., model PVA1788.

[0035] Preparation Examples 1-4: Preparation of Modified Nano-Silica Preparation Example 1 Take 3 kg of tetraethyl orthosilicate and 1 kg of γ-glycidoxypropyltrimethoxysilane and disperse them in 10 kg of 50 wt% ethanol aqueous solution. Stir well and add 25 wt% ammonia water dropwise to adjust the pH of the system to 9.5. Heat to 70℃ and stir for 5 h. After the reaction is completed, centrifuge to separate the product and wash it 3-5 times with anhydrous ethanol. Dry it under vacuum to constant weight and grind it through a 200 mesh sieve to obtain white powdered epoxy-modified nano silica.

[0036] Preparation Example 2 2 kg of tetraethyl orthosilicate and 1 kg of γ-glycidyl etheroxypropyltrimethoxysilane were dispersed in 10 kg of 50 wt% ethanol aqueous solution and stirred evenly. 25 wt% ammonia was added dropwise to adjust the pH of the system to 9. The temperature was raised to 60 °C and the reaction was stirred for 6 h. After the reaction was completed, the product was separated by centrifugation and washed 3-5 times with anhydrous ethanol. The product was dried under vacuum to constant weight and ground through a 200-mesh sieve to obtain white powdered epoxy-modified nano-silica.

[0037] Preparation Example 3 4 kg of tetraethyl orthosilicate and 1 kg of γ-glycidyl etheroxypropyltrimethoxysilane were dispersed in 10 kg of 50 wt% ethanol aqueous solution and stirred evenly. 25 wt% ammonia was added dropwise to adjust the pH of the system to 10. The temperature was raised to 80 °C and the reaction was stirred for 4 h. After the reaction was completed, the product was separated by centrifugation and washed 3-5 times with anhydrous ethanol. The product was dried under vacuum to constant weight and ground through a 200-mesh sieve to obtain white powdered epoxy-modified nano-silica.

[0038] Preparation Example 4 Preparation Example 4 is basically the same as Preparation Example 1, except that γ-glycidoxypropyltrimethoxysilane is replaced with an equal amount of γ-aminopropyltriethoxysilane to obtain amino-modified nano silica.

[0039] Example 1 The preparation method of high-viscosity modified emulsified asphalt in this embodiment includes the following steps: S1. Preparation of acidic soap solution: Take 3.25 kg of deionized water, heat to 45℃, adjust the pH to 2.5 with 37 wt% hydrochloric acid, add 0.3 kg of premixed composite emulsifier and 0.02 kg of stabilizer, stir at 200 r / min until completely dissolved to obtain acidic soap solution, keep warm for later use; S2. Preparation of alkaline activation solution: Take 1.75 kg of deionized water and add it to a high-speed dispersion vessel. Heat the vessel to 60°C and adjust the pH to 9.5 with 25 wt% ammonia water. Then add 0.4 kg of amino-terminated hyperbranched polyamide, 0.4 kg of amino-terminated liquid butadiene-acrylonitrile, and 0.1 kg of epoxy-modified nano-silica (from preparation example 1) in sequence. Disperse the mixture at 2500 r / min for 25 min to obtain the alkaline activation solution. S3. Primary Emulsification: Place 10 kg of base asphalt in a heating tank, start stirring at 400 r / min, heat to 160℃, and hold for 23 min until the asphalt is completely melted to obtain molten asphalt; preheat the colloid mill to 45℃, introduce the acidic soap solution from step S1 into it, control the stirring speed at 1200 r / min, introduce the heated asphalt into the colloid mill (feeding speed controlled at 2.9 kg / min), then adjust the colloid mill speed to 3000 r / min, shear emulsify for 4 min to obtain the primary emulsion; S4. Secondary compounding: Cool the primary emulsion from step S3 to 52°C, and add the alkaline activating liquid from step S2, 0.1 kg of premixed composite emulsifier, and 0.3 kg of epoxy resin emulsion in sequence while stirring at 500 r / min. Continue stirring for 12 min, then quickly cool to room temperature and filter to obtain high-viscosity emulsified asphalt. The premixed composite emulsifier is obtained by mixing hexadecyltrimethylammonium bromide, alkyl polysaccharide and lignin amine in a mass ratio of 2:1:1; the stabilizer is obtained by mixing ammonium chloride and polyvinyl alcohol in a mass ratio of 1:1.

[0040] Example 2 The method for high-viscosity modified emulsified asphalt in this embodiment includes the following steps: S1. Preparation of acidic soap solution: Take 2.7 kg of deionized water, heat to 40℃, adjust the pH to 2 with 37 wt% hydrochloric acid, add 0.225 kg of premixed composite emulsifier and 0.01 kg of stabilizer, stir at 150 r / min until completely dissolved to obtain acidic soap solution, keep warm for later use; S2. Preparation of alkaline activation solution: Take 1.8 kg of deionized water and add it to a high-speed dispersion vessel. Heat the vessel to 55°C and adjust the pH to 9 with 25 wt% ammonia. Then add 0.3 kg of amino-terminated hyperbranched polyamide, 0.15 kg of amino-terminated liquid butadiene-acrylonitrile, and 0.08 kg of epoxy-modified nano-silica (from preparation example 2) in sequence. Disperse the mixture at 2000 r / min for 30 min to obtain the alkaline activation solution. S3. Primary Emulsification: Place 10 kg of base asphalt in a heating tank, start stirring at 300 r / min, heat to 150℃, and hold for 25 min until the asphalt is completely melted to obtain molten asphalt; preheat the colloid mill to 40℃, introduce the acidic soap solution from step S1 into it, control the stirring speed at 1200 r / min, introduce the heated asphalt into the colloid mill (feeding speed controlled at 2.5 kg / min), then adjust the colloid mill speed to 2500 r / min, shear emulsify for 5 min to obtain the primary emulsion; S4. Secondary compounding: Cool the primary emulsion from step S3 to 50°C, and add the alkaline activating liquid from step S2, 0.075 kg of composite emulsifier, and 0.2 kg of epoxy resin emulsion sequentially while stirring at 400 r / min. Continue stirring for 10 min, then quickly cool to room temperature and filter through a 100-mesh nylon sieve to obtain high-viscosity emulsified asphalt. The premixed composite emulsifier is obtained by mixing hexadecyltrimethylammonium bromide, alkyl polysaccharide and lignin amine in a mass ratio of 2:0.9:0.9; the stabilizer is obtained by mixing ammonium chloride and polyvinyl alcohol in a mass ratio of 1:0.9.

[0041] Example 3 The preparation method of high-viscosity modified emulsified asphalt in this embodiment includes the following steps: S1. Preparation of acidic soap solution: Take 3.85 kg of deionized water and heat it to 50°C. Adjust the pH to 3 with 37 wt% hydrochloric acid. Add 0.375 kg of premixed composite emulsifier and 0.03 kg of stabilizer. Stir at 250 r / min until completely dissolved to obtain acidic soap solution. S2. Preparation of alkaline activation solution: Take 1.65 kg of deionized water and add it to a high-speed dispersion vessel. Heat the vessel to 65°C and adjust the pH to 10 with 25 wt% ammonia. Then add 0.5 kg of amino-terminated hyperbranched polyamide, 0.25 kg of amino-terminated liquid butadiene-acrylonitrile, and 0.12 kg of epoxy-modified nano-silica (from preparation example 3) in sequence. Disperse the mixture at 3000 r / min for 20 min to obtain the alkaline activation solution. S3. Primary Emulsification: Place 10 kg of base asphalt in a heating tank, start stirring at 500 r / min, heat to 170℃, and hold for 20 min until the asphalt is completely melted to obtain molten asphalt; preheat the colloid mill to 50℃, introduce the acidic soap solution from step S1 into it, control the stirring speed at 1200 r / min, introduce the heated asphalt into the colloid mill (feeding speed controlled at 3.3 kg / min), then adjust the colloid mill speed to 3500 r / min, shear emulsify for 3 min to obtain the primary emulsion; S4. Secondary compounding: Cool the primary emulsion from step S3 to 55°C, and add the alkaline activating liquid from step S2, the remaining 0.125 kg of premixed compound emulsifier, and 0.4 kg of epoxy resin emulsion in sequence while stirring at 600 r / min. Continue stirring for 15 min, then quickly cool to room temperature and filter through a 100-mesh nylon sieve to obtain high-viscosity emulsified asphalt. The premixed composite emulsifier is obtained by mixing hexadecyltrimethylammonium bromide, alkyl polysaccharide and lignin amine in a mass ratio of 2:1.1:1.1; the stabilizer is obtained by mixing ammonium chloride and polyvinyl alcohol in a mass ratio of 1:1.1.

[0042] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that in Comparative Example 1, the terminal amino hyperbranched polyamide is replaced with an equal amount of terminal amino liquid butadiene-acrylonitrile.

[0043] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that no terminal amino hyperbranched polyamide was added in Comparative Example 2.

[0044] Comparative Example 3 Comparative Example 3 is basically the same as Example 1, except that in Comparative Example 3, the epoxy-modified nano silica is replaced with an equal amount of amino-modified nano silica (from Preparation Example 4).

[0045] Comparative Example 4 Comparative Example 4 is basically the same as Example 1, except that no epoxy-modified nano-silica was added in Comparative Example 4.

[0046] Comparative Example 5 Comparative Example 5 is basically the same as Example 1, except that the preparation method of the high-viscosity emulsified asphalt specifically includes the following steps: S1. Preparation of soap solution: Take 3.25 kg of deionized water, heat it to 45°C, add 0.3 kg of premixed composite emulsifier and 0.02 kg of stabilizer, stir at 200 r / min until completely dissolved to obtain the basic soap solution; S2. Take 1.75 kg of deionized water and add it to a high-speed dispersion vessel. Heat the vessel to 60°C and add 0.4 kg of amino-terminated hyperbranched polyamide, 0.4 kg of amino-terminated liquid butadiene-acrylonitrile, and 0.1 kg of epoxy-modified nano-silica (from Preparation Example 1) and the basic soap solution from step S1 in sequence. Disperse the solution at 2500 r / min for 25 min to obtain a composite soap solution. S3. Emulsification: Place 10 kg of base asphalt in a heating tank, turn on the stirrer at 400 r / min, heat to 160℃, and keep warm for 23 min until the asphalt is completely melted to obtain molten asphalt; preheat the colloid mill to 45℃, introduce the composite soap solution from step S2 into it, control the stirring speed at 1200 r / min, introduce the heated asphalt into the colloid mill (feeding speed controlled at 2.9 kg / min), then adjust the speed of the colloid mill to 3000 r / min, and shear emulsify for 4 min to obtain the primary emulsion; S4. Secondary compounding: Cool the primary emulsion from step S3 to 52°C, and add 0.1 kg of premixed compound emulsifier and 0.3 kg of epoxy resin emulsion sequentially while stirring at 500 r / min. Continue stirring for 12 min, then quickly cool to room temperature and filter through a 100-mesh nylon sieve to obtain high-viscosity emulsified asphalt. The premixed composite emulsifier is obtained by mixing hexadecyltrimethylammonium bromide, alkyl polysaccharide and lignin amine in a mass ratio of 2:1:1; the stabilizer is obtained by mixing ammonium chloride and polyvinyl alcohol in a mass ratio of 1:1.

[0047] Performance testing The properties of the emulsified asphalts prepared in Examples 1-3 and Comparative Examples 1-5 were tested according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025). The test results are shown in Table 1.

[0048] Table 1 Performance test results of high-viscosity emulsified asphalt

[0049] As can be seen from the test results in Table 1, the high-viscosity emulsified asphalt prepared in Examples 1-3 of this invention meets the requirements of high-standard engineering in all performance indicators; the 5-day storage stability is 1.5%-2.1%; the dynamic viscosity of the evaporation residue at 60℃ reaches 54673-58168 Pa·s, and the softening point reaches above 91℃; the ductility at 5℃ is 32-41 cm. Compared to Example 1, the high-viscosity emulsified asphalt in Comparative Examples 1-2 showed a significant decrease in dynamic viscosity / softening point at 60°C and a significant deterioration in storage stability. This indicates that the high-density terminal amino groups provided by the three-dimensional spherical structure of the end-amino hyperbranched polyamide are the core nodes for forming a dense chemical crosslinking network. When the end-amino hyperbranched polyamide is missing, a dense rigid skeleton cannot be constructed, resulting in a significant decrease in viscosity and softening point. The asphalt particles lack an effective organic-inorganic interface layer on their surface, making them prone to demulsification and aggregation, leading to increased particle density differences and easy sedimentation and stratification during storage. Furthermore, the linear ATBN has limited compatibility and tends to agglomerate within the particles, further compromising emulsion stability.

[0050] Compared to Example 1, the 5-day storage stability of Comparative Examples 3-4 was significantly deteriorated, with a decrease in dynamic viscosity and softening point at 60°C. In Comparative Example 3, an equal amount of amino-modified nano-silica was used instead of epoxy-modified nano-silica. On the one hand, the amino groups on its surface competed with the amino groups in the polymer system and could not be effectively anchored, thus failing to form an organic-inorganic interface layer with the terminal amino hyperbranched polyamide. The particles were prone to demulsification and aggregation, and had poor compatibility in the organic phase, resulting in reduced storage stability. On the other hand, it could not act as an inorganic crosslinking point to participate in the crosslinking reaction of the polymer and form a stress transmission hub, resulting in a decrease in viscosity, low-temperature ductility, and softening point. Comparative Example 4 did not add epoxy-modified nano-silica, thus losing its hybrid reinforcement and thixotropic stabilizing effects. On the one hand, without inorganic nodes to disperse stress, the chemical crosslinking network was prone to local stress concentration, leading to a decrease in viscosity. On the other hand, without thixotropic network support, the asphalt particles settled due to density differences, resulting in deteriorated 5-day storage stability.

[0051] Compared to Example 1, Comparative Example 5, which uses a one-step emulsification process (without acid-activated emulsifier, alkali-activated modifier, and acid-base neutralization process) to premix all aqueous components, showed a slight decrease in dynamic viscosity at 60°C and a significant deterioration in storage stability. The reason for this is that, due to the absence of alkali-activated modifier, the terminal amino hyperbranched polyamide and epoxy-modified nano-silica could not form an effective organic-inorganic hybrid interface layer on the surface of asphalt particles, resulting in insufficient stability of the formed interface film and easy demulsification and aggregation of particles. This also demonstrates that the acid-base neutralization process achieves in-situ, directional anchoring of the modified components on the surface of asphalt particles, effectively avoiding phase separation and component agglomeration problems caused by simple blending, and ensuring that the cross-linked network constructed by the modified components can be truly established around and between the asphalt particles, thereby achieving optimal performance.

[0052] In summary, this invention ensures, through time and pH control of the preparation process, that the synergistic cross-linking network structure constructed by the terminal amino hyperbranched polyamide, terminal amino liquid butadiene-acrylonitrile, epoxy-modified nano silica, and epoxy resin emulsion modified components can be truly established around and between asphalt particles, thereby achieving optimal performance. This solves the technical problems of traditional high-viscosity emulsified asphalt, such as the contradiction between viscosity and workability, difficulty in balancing high and low temperature performance, poor storage stability, and easy peeling of components.

[0053] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing high-viscosity emulsified asphalt, characterized in that, Includes the following steps: S1. Preparation of acidic soap solution: Heat part of the deionized water to 40-50℃, adjust the pH to 2-3, add part of the composite emulsifier and stabilizer, stir until completely dissolved, and obtain acidic soap solution. Keep warm for later use. S2. Preparation of alkaline activation solution: Heat the remaining deionized water to 55-65℃, adjust the pH to 9-10, add amino-terminated hyperbranched polyamide, amino-terminated liquid butadiene-acrylonitrile and epoxy-modified nano silica, and disperse at high speed at 2000-3000r / min for 20-30min to obtain alkaline activation solution. S3. Primary emulsification: After heating the base asphalt to 150℃-170℃, pour it into the acidic soap solution from step S1, and shear emulsify it for 3-5 minutes using a colloid mill at a speed of 2500-3500r / min to obtain the primary emulsion. S4. Secondary compounding: Cool the primary emulsion from step S3 to 50-55℃, and add the alkaline activating liquid from step S2, the remaining compound emulsifier, and the epoxy resin emulsion in sequence while stirring. Continue stirring for 10-15 minutes, then quickly cool to room temperature and filter to obtain high-viscosity emulsified asphalt.

2. The method for preparing high-viscosity emulsified asphalt according to claim 1, characterized in that, The stirring speed in step S1 is 150-250 r / min.

3. The method for preparing high-viscosity emulsified asphalt according to claim 1, characterized in that, In step S3, the feeding rate of hot asphalt added to the acidic soap solution is 2.5-3.3 kg / min.

4. The method for preparing high-viscosity emulsified asphalt according to claim 1, characterized in that, The stirring speed in step S4 is 400-600 r / min.

5. A high-viscosity emulsified asphalt, characterized in that, It is prepared by the method described in any one of claims 1-4.

6. The high-viscosity emulsified asphalt according to claim 5, characterized in that, The raw materials include the following parts by weight: 100 parts of base asphalt; 3.0-5.0 parts of composite emulsifier; 3-5 parts of amino-terminated hyperbranched polyamide; 1.5-2.5 parts of amino-terminated liquid butadiene-acrylonitrile; 0.8-1.2 parts of epoxy-modified nano silica; 2-4 parts of epoxy resin emulsion; 0.1-0.3 parts of stabilizer; and 45-55 parts of water.

7. The high-viscosity emulsified asphalt according to claim 6, characterized in that, The preparation method of the epoxy-modified nano-silica includes the following steps: Tetraethyl orthosilicate and epoxy silane coupling agent are dispersed in an aqueous ethanol solution, stirred until homogeneous, the pH of the system is adjusted to 9-10, the temperature is raised to 60-80℃, and the reaction is stirred for 4-6 hours. The product is then separated, washed, vacuum dried, and ground to obtain the final product.

8. The high-viscosity emulsified asphalt according to claim 6, characterized in that, The composite emulsifier is obtained by compounding hexadecyltrimethylammonium bromide, alkyl polysaccharide and ligninamine.

9. The high-viscosity emulsified asphalt according to claim 6, characterized in that, The stabilizer is obtained by compounding ammonium chloride and polyvinyl alcohol.

10. The high-viscosity emulsified asphalt according to claim 6, characterized in that, The epoxy resin emulsion is an aqueous epoxy resin emulsion with a solid content of 50%-54% and an epoxy equivalent of 450-550 g / eq.

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