Tough synergy type composite modified asphalt for hydraulic panel leveling layer and preparation method thereof

Abstract

The application discloses a strong and tough synergic composite modified asphalt for hydraulic panel leveling layer and a preparation method thereof. Raw materials of the composite modified asphalt include base asphalt, composite modifier, rubber oil and vulcanizing agent. Raw materials of the composite modifier include epoxidized castor oil, HDI (hexamethylene diisocyanate), polymerization inhibitor, phthalic anhydride, inhibitor and chain termination agent. The application drops HDI into the epoxidized castor oil with the polymerization inhibitor to generate epoxidized polyurethane. The epoxidized polyurethane, phthalic anhydride and inhibitor are formed into composite glue particles with a certain size by a granulator. The crosslinking network of the long chain of the epoxidized castor oil and the HDI can effectively help the modified asphalt to realize strong and tough synergy, and the control of the crosslinking density can effectively reduce the viscosity of the modified asphalt, so that the material is more suitable for preparing the asphalt concrete for the strong and tough synergic, long service life hydraulic asphalt concrete panel leveling and cementing layer.

Description

Technical Field

[0001] This invention relates to the field of asphalt modification technology, and in particular to a strong and tough synergistic composite modified asphalt for hydraulic panel leveling layers and its preparation method. Background Technology

[0002] The hydraulic asphalt concrete panel can be divided into a sealing layer, a seepage-proof layer, a drainage layer, a seepage-proof bottom layer, a leveling and bonding layer, and a bottom bedding layer from top to bottom. The leveling and bonding layer plays a role in supporting the upper structure and tightly bonding with the lower structure. It provides a flat and solid foundation for the upper layer, ensures that the seepage-proof layer is laid evenly, transmits stress, and prevents slippage and separation between the upper and lower layers.

[0003] Currently, the materials widely used in leveling binders are base asphalt and SBS modified asphalt. These asphalt materials have poor toughness, which means that the leveling binder does not have enough strength to support the superstructure and effectively resist the damage caused by the superstructure load. It is also susceptible to stress concentration, which can lead to cracking.

[0004] Existing technologies utilize bio-based raw materials and polyols to generate prepolymers through addition polymerization, followed by chain extender reactions to produce polymer materials, which are then applied to asphalt systems to enhance the material's toughness, tear resistance, and abrasion resistance. However, the reaction process of generating polyurethane from bio-based raw materials and polyols is relatively fast, and the reaction between isocyanate and hydroxyl groups is a strongly exothermic reaction. Existing technologies still have the following problems:

[0005] 1. The temperature fluctuations during the reaction are large and difficult to control, affecting the performance of the synthesized materials. An excessively fast reaction rate leads to a sudden drop in system temperature, accelerating cross-linking, causing the synthesized modified asphalt to lose its processability and performance controllability, ultimately forming an irreversible gel.

[0006] 2. Increased viscosity of synthetic materials leads to increased sensitivity to temperature dissipation. During the construction of hydraulic asphalt concrete in low-temperature environments, asphalt with higher viscosity tends to solidify rapidly. At high temperatures, its good dispersion properties are rapidly lost as the temperature decreases, resulting in insufficient interfacial bonding between the asphalt binder system and aggregate particles. This prevents effective wetting of the aggregate surface and the formation of a continuous coating layer, thereby affecting the mechanical properties and durability of the asphalt binder and making it unsuitable for use as a leveling binder layer in hydraulic asphalt concrete panels. Summary of the Invention

[0007] The technical problem this invention aims to solve is to address the shortcomings of the existing technology by providing a strong and synergistic composite modified asphalt for leveling hydraulic asphalt panels and its preparation method. The invention uses epoxidized castor oil, HDI, polymerization inhibitors, phthalic anhydride, inhibitors, chain terminators, and other materials to prepare a composite modified material. Then, base asphalt, rubber oil, and a vulcanizing agent are added to finally obtain the composite modified asphalt. This invention effectively controls the reaction process, enhancing the toughness, tear resistance, and abrasion resistance of the modified asphalt while reducing viscosity and temperature sensitivity, thus making it suitable for leveling and bonding layers in hydraulic asphalt concrete panels.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A composite modified asphalt for a strong and synergistic leveling layer of hydraulic asphalt concrete panels, characterized in that: the raw materials of the composite modified asphalt are proportioned in the following mass parts:

[0010] 65-72 parts of base asphalt

[0011] 22-28 parts of composite modified material

[0012] 6-8 parts of rubber oil

[0013] Vulcanizing agent 0.3-0.4 parts,

[0014] The raw materials of the composite modifier are proportioned in the following mass parts:

[0015] Epoxidized castor oil 30-38 parts

[0016] HDI (hexamethylene diisocyanate) 55-65 parts

[0017] Polymerization inhibitor 0.5-1.0 parts,

[0018] Phthalic anhydride 5-6 parts

[0019] Chain terminator 1.5-2.0 parts,

[0020] Inhibitor 0.2-0.3 parts.

[0021] Epoxidized castor oil is prepared from castor oil via acid-catalyzed peroxidation. This peroxidation reaction introduces epoxy groups, which can crosslink with the isocyanate groups of HDI and the active hydrogen in asphalt, forming a more stable three-dimensional network, enhancing reactivity and improving the material's mechanical properties. The strong interaction between the epoxy groups and the polar components of asphalt reduces phase separation and improves the interfacial compatibility between polyurethane and asphalt. The epoxidized structure reduces the hydrophilicity of castor oil and enhances hydrolysis resistance, allowing the material to maintain good sealing and mechanical properties even after long-term exposure to wind and rain, making it suitable for hydraulic engineering environments.

[0022] HDI possesses a flexible aliphatic chain structure, which imparts soft segments to polyurethane. This, combined with the rigid network of epoxidized castor oil, synergistically enhances the elongation at break of the composite modified asphalt. It combines long-chain flexibility with cross-linking rigidity, significantly improving the material's toughness. The aliphatic HDI structure exhibits strong resistance to UV aging, and its hydrophobic properties, combined with the hydrophobic properties of epoxidized castor oil, extend the material's outdoor service life. It is suitable for hydraulic applications such as leveling cementitious layers exposed to long-term exposure, offering superior weather resistance. Furthermore, HDI has low volatility and low toxicity, meeting environmental protection requirements.

[0023] Epoxidized castor oil long chains provide high toughness, while HDI crosslinking networks enhance rigidity, effectively helping modified asphalt achieve a synergistic effect of strength and toughness. Furthermore, epoxidized polyurethane has a microphase separation structure of soft segments (epoxidized castor oil long chains) and hard segments (urethane groups). The soft segments have a higher glass transition temperature, while the asphalt has a lower one, making them complementary at low temperatures: asphalt is prone to embrittlement when it enters the glassy state, while the soft segments retain the flexibility of the molecular chains, absorbing and releasing stress through the local movement of the molecular chains, thus delaying the increase in system viscosity; while the three-dimensional network formed by the hard segments maintains the overall structural stability of the material and avoids low-temperature embrittlement. This dynamic network of soft and hard segment microphase separation can significantly reduce the sensitivity of asphalt to temperature loss, ensuring that the asphalt retains its workability after transitioning from the high-temperature construction environment to the low-temperature environment.

[0024] Phthalic anhydride primarily functions as an interfacial compatibilizer. Through the reaction of its anhydride groups with the epoxy groups of epoxidized castor oil and the isocyanate groups of HDI, it enhances the compatibility between the polyurethane network and the asphalt phase, while simultaneously regulating the curing reaction rate to prevent excessive crosslinking. However, the dosage of phthalic anhydride should not be too high. When the grafting reaction between phthalic anhydride and asphalt reaches equilibrium, the ratio of phthalic anhydride to asphalt is fixed. As the amount of phthalic anhydride increases, the mechanical properties of the modified asphalt, such as strength and toughness, no longer improve but decrease. Excessive phthalic anhydride can lead to excessively high crosslinking density in the polyurethane network, resulting in embrittlement of the polyurethane-asphalt interface.

[0025] The base asphalt is at least one of natural asphalt, petroleum asphalt, and coal tar pitch. Preferably, the base asphalt is 90# petroleum asphalt with a penetration (25℃) of 80-100 (0.1mm).

[0026] The chain terminator is at least one of thiobisphenol, quinone derivatives, and aromatic amines. The chain terminator blocks the chain reaction by chemically binding to or neutralizing free radicals, inhibiting oxidation or degradation processes and enhancing the anti-aging ability of asphalt.

[0027] The vulcanizing agent is at least one selected from dicumyl peroxide, sulfur, and di-tert-butyl peroxide. Its function is to form a stable three-dimensional polymer network through dynamic vulcanization, promoting the cross-linking reaction between the composite modifier and asphalt, and improving the storage stability of the modified asphalt.

[0028] The polymerization inhibitor is at least one of p-toluenesulfonic acid, dibutyl phthalate, and p-hydroxyanisole. p-Toluenesulfonic acid inhibits the condensation reaction between isocyanate and hydroxyl groups; dibutyl phthalate acts as a plasticizer, reducing system viscosity and delaying gelation; p-hydroxyanisole captures free radicals, preventing HDI self-polymerization, providing multiple polymerization inhibition mechanisms. The reaction process can be specifically controlled according to environmental needs, preventing a sudden increase in system viscosity or premature gelation.

[0029] The inhibitor is at least one of BHT (butylated hydroxytoluene), dilauryl thiodipropionate, and diphenylamine. Its main function is to inhibit the excessive crosslinking reaction between HDI and epoxidized castor oil, preventing excessive self-polymerization of HDI or rapid reaction with hydroxyl groups to form a rigid network, which would lead to excessively high asphalt viscosity and reduced compaction. The inhibitor dynamically regulates the reactivity of HDI with hydroxyl / epoxy groups through a synergistic mechanism of free radical capture, catalyst poisoning, and intermediate stabilization, thereby balancing crosslinking density and workability.

[0030] The preparation method of the composite modified asphalt for the high-strength and synergistic hydraulic asphalt concrete panel leveling layer according to claim 1 includes the following steps:

[0031] Step 1: Preparation of epoxidized polyurethane: Add 1-3% polymerization inhibitor to epoxidized castor oil, add liquid HDI dropwise to epoxidized castor oil at a temperature of 80-90℃, and stir to generate epoxidized polyurethane. The addition ratio of liquid HDI to epoxidized castor oil is between 1:1.45 and 1:2.15.

[0032] Step 2: Preparation of composite modified material: To avoid local overheating, the material is fed in stages. The epoxidized polyurethane, phthalic anhydride, inhibitor, and chain terminator are fed in stages in the order described above, and chemical force is used for melt blending. The mixture is then granulated by a granulator to become a composite modified material.

[0033] Step 3: Preparation of composite modified asphalt: The composite modifier and rubber oil are added to the base asphalt, and the vulcanizing agent is slowly added after high-speed shearing. After swelling and development, the composite modified asphalt is obtained.

[0034] In step 1, the temperature at which liquid HDI is added is 85°C. The isocyanate index R of the reaction between liquid HDI and epoxidized castor oil is 1.6–1.8, preferably 1.7, to prevent self-polymerization of HDI due to its high activity. The aliphatic chain structure of HDI forms soft segments through gradual polymerization, while the separation of hard segments (urethane groups) from soft segments (epoxidized castor oil segments) ensures the high toughness of the material. Meanwhile, during the reaction of epoxidized castor oil and HDI to form polyurethane, an excessively rapid reaction rate leads to a sudden rise in system temperature, accelerating crosslinking and ultimately forming an irreversible gel with a rapid increase in viscosity, affecting industrial production. Therefore, a polymerization inhibitor is needed to suppress the rapid reaction between HDI and the hydroxyl groups of epoxidized castor oil. Adding a polymerization inhibitor can maintain the system at a low viscosity without reducing the mechanical properties of the final polyurethane, which is beneficial for enhancing the toughness of the modified asphalt.

[0035] In step 3, the high-speed shearing speed is 4000-6000 r / min and the shearing time is 30-45 min to ensure uniform dispersion of the composite modifier and avoid asphalt aging during the shearing preparation process; the stirring speed for swelling development is 200-300 r / min and the stirring time is 90-120 min; the temperature for both high-speed shearing and swelling development is 170-180℃.

[0036] Polyurethane is highly prone to curing and segregation, stratifying and precipitating in asphalt systems. This application addresses this by preparing a composite modifier to form homogenized composite particles, enhancing the compatibility of the polyurethane network with asphalt, reducing phase separation problems, and allowing the polymer to be more uniformly dispersed in the asphalt, thus improving the overall homogeneity of the material. Simultaneously, the crosslinking reaction process of the composite particles can be controlled through granulation. The granulated particle structure physically isolates and slows down the rapid reaction between HDI and hydroxyl groups. Inhibitors (such as BHT) in the composite particles suppress excessive crosslinking of HDI and epoxidized castor oil through free radical capture and reactivity regulation. The particle structure formed after granulation allows the crosslinking density to be gradually released during processing, avoiding excessive crosslinking during modification that leads to excessively high viscosity or gelation, thus ensuring workability.

[0037] Based on the application of the composite modified asphalt according to claim 1, the characteristic is that it is applied to the leveling and bonding layer of hydraulic asphalt concrete panels.

[0038] The present invention has the following beneficial effects:

[0039] 1. The long chains of epoxidized castor oil provide high toughness, while the HDI crosslinking network enhances rigidity, synergistically improving the toughness, tear resistance, and abrasion resistance of modified asphalt. Furthermore, the epoxidized polyurethane has a microphase separation structure of soft segments (long chains of epoxidized castor oil) and hard segments (urethane groups). The soft segments have a higher glass transition temperature, while the asphalt has a lower one, making them complementary at low temperatures: asphalt is prone to embrittlement when it enters the glassy state, while the soft segments retain the flexibility of the molecular chains, absorbing and releasing stress through localized molecular chain movement, thus delaying the increase in system viscosity. Meanwhile, the three-dimensional network formed by the hard segments maintains the overall structural stability of the material, preventing low-temperature embrittlement. This dynamic network of soft and hard segment microphase separation can significantly reduce the sensitivity of asphalt to temperature loss, ensuring that the asphalt retains its workability after transitioning from a high-temperature construction environment to a low-temperature environment.

[0040] 2. This invention employs a multi-stage reaction control technology, adding polymerization inhibitors, depressants, and chain terminators in stages during the reaction process to control the exothermic reaction and regulate the reaction progress. The polymerization inhibitors provide multiple inhibition mechanisms, rather than relying solely on a single acidic environment to suppress the reaction; the depressants further control excessive cross-linking; and the chain terminators block the chain reaction. The three work synergistically to regulate the cross-linking density, reduce the system viscosity, and thus reduce the temperature sensitivity of the modified asphalt.

[0041] 3. This invention uses a granulation process to prepare composite modified asphalt, regulates the crosslinking reaction process, controls the system temperature by segmented feeding to avoid local overheating, and the particle structure formed after granulation allows the crosslinking density to be gradually released during processing, avoiding excessive crosslinking during modification that leads to excessively high viscosity or gelation, thus ensuring construction performance.

[0042] 4. The composite modifier prepared by this invention has good compatibility with asphalt, solving the processing problems caused by excessive reaction rate and over-reaction of high-polymer-modified asphalt. It allows for the incorporation of higher polymer content into the modified asphalt system, enhancing the toughness, tear resistance and wear resistance of the modified asphalt, while reducing the temperature sensitivity of the modified asphalt, making it more suitable for the leveling and bonding layer of hydraulic asphalt concrete panels.

[0043] 5. The composite modified asphalt prepared by this invention is resistant to ultraviolet aging and has strong hydrolysis resistance, which extends the service life of the material in the hydraulic environment; it has low toxicity and is not easily volatile, thus ensuring environmental performance; and the higher dosage of epoxidized castor oil reduces costs, making it more suitable for the leveling and bonding layer of hydraulic asphalt concrete panels that are strong and tough, unaffected by temperature, and have a long service life. Attached Figure Description

[0044] none. Detailed Implementation

[0045] The present invention will be further illustrated by the following embodiments, but the scope of protection of the claims of the present invention is not limited by the embodiments.

[0046] The sources of the raw materials used in the embodiments of this invention are as follows:

[0047] The base asphalt consisted of 90# and 70# petroleum asphalt, purchased from Jiangsu Xinyue Asphalt Co., Ltd.

[0048] The chain terminator is one or more of thiobisphenol, quinone derivatives and aromatic amines, purchased from Hubei Xinrunde Chemical Co., Ltd.

[0049] Rubber oil, purchased from Jiangsu Zhonghong Green Environmental Protection Co., Ltd.

[0050] The vulcanizing agent is one or more of dicumyl peroxide, sulfur, and di-tert-butyl peroxide, purchased from Shandong Xuchen Chemical Technology Co., Ltd.

[0051] Epoxidized castor oil, purchased from Jiangsu Shenglun Chemical Technology Co., Ltd.

[0052] HDI (hexamethylene diisocyanate), purchased from Jiangsu Bost Chemical Technology Co., Ltd.

[0053] The polymerization inhibitor is one or more of p-toluenesulfonic acid, dibutyl phthalate and p-hydroxyanisole, purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0054] Phthalic anhydride was purchased from Shandong Xuchen Chemical Technology Co., Ltd.

[0055] The inhibitors are one or more of BHT (butylated hydroxytoluene), dilaurate thiodipropionate, and diphenylamine, purchased from Anhui Haihua Technology Group Co., Ltd.

[0056] Example 1

[0057] A composite modified asphalt (1#) for a strong and synergistic leveling layer of hydraulic asphalt concrete panels, which is used as a leveling binder layer for hydraulic asphalt concrete panels, comprises the following components by weight:

[0058]

[0059] The composite modifier is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor and chain terminator.

[0060] in:

[0061] The base asphalt is 90# petroleum asphalt.

[0062] The composite modified material comprises the following components by weight:

[0063]

[0064] The inhibitor mentioned is BHT.

[0065] The chain terminator is thiobisphenol.

[0066] The vulcanizing agent is dicumyl peroxide.

[0067] The polymerization inhibitor is p-toluenesulfonic acid.

[0068] The preparation method of the composite modified asphalt for the above-mentioned strong and tough synergistic hydraulic asphalt concrete panel leveling layer includes the following steps:

[0069] (1) Take 30 parts by weight of epoxidized castor oil, add 0.5 parts by weight of polymerization inhibitor, and add 65 parts by weight of liquid HDI at 85°C. Stir at 500 r / min for 30 min to generate epoxidized polyurethane. Control the isocyanate index R of the reaction between liquid HDI and epoxidized castor oil to be 1.7.

[0070] (2) The prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, 1.5 parts by mass of chain terminator and 0.2 parts by mass of inhibitor were added in the order of polyurethane-phthalic anhydride-inhibitor-chain terminator and chemically melt-blended, and the composite modified material was prepared by granulation.

[0071] (3) Add 22 parts by weight of the composite modifier and 6 parts by weight of the rubber oil to 72 parts by weight of 90# base asphalt, raise the temperature of the mixture to 175°C, shear at 6000 r / min for 45 min, add 0.3 parts by weight of the vulcanizing agent, keep the temperature at 175°C, stir at 300 r / min for 120 min to swell and develop, and then obtain the composite modified asphalt.

[0072] Example 2

[0073] A composite modified asphalt (2#) for a strong and synergistic leveling layer of hydraulic asphalt concrete panels, which is used as a leveling binder layer for hydraulic asphalt concrete panels, comprises the following components by weight:

[0074]

[0075] The composite modifier is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor and chain terminator.

[0076] in:

[0077] The base asphalt is 70# petroleum asphalt.

[0078] The composite modified material comprises the following components by weight:

[0079]

[0080] The inhibitor is dilaurate thiodipropionate.

[0081] The chain terminator is a quinone derivative.

[0082] The vulcanizing agent is sulfur.

[0083] The polymerization inhibitor is dibutyl phthalate.

[0084] The preparation method of the composite modified asphalt for the above-mentioned strong and tough synergistic hydraulic asphalt concrete panel leveling layer includes the following steps:

[0085] (1) Take 34 parts by mass of epoxidized castor oil, add 0.7 parts by mass of polymerization inhibitor, and add 62 parts by mass of liquid HDI dropwise at 80°C. Stir at 300 r / min for 50 min to generate epoxidized polyurethane. Control the isocyanate index R of the reaction between liquid HDI and epoxidized castor oil to be 1.6.

[0086] (2) The prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, 1.8 parts by mass of chain terminator and 0.3 parts by mass of inhibitor were added in the order of polyurethane-phthalic anhydride-inhibitor-chain terminator and chemically melt-blended, and the composite modified material was prepared by granulation.

[0087] (3) Add 26 parts by weight of the composite modifier and 7 parts by weight of the rubber oil to 68 parts by weight of 70# base asphalt, raise the temperature of the mixture to 170°C, shear at 4000 r / min for 30 min, add 0.3 parts by weight of the vulcanizing agent, keep the temperature at 170°C, stir at 200 r / min for 90 min to swell and develop, and then obtain the composite modified asphalt.

[0088] Example 3

[0089] A composite modified asphalt (3#) for a strong and synergistic leveling layer of hydraulic asphalt concrete panels, which is used as a leveling binder layer for hydraulic asphalt concrete panels, comprises the following components by weight:

[0090]

[0091] The composite modifier is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor and chain terminator.

[0092] in:

[0093] The base asphalt is 90# petroleum asphalt.

[0094] The composite modified material comprises the following components by weight:

[0095]

[0096] The inhibitor is diphenylamine.

[0097] The chain terminator is an aromatic amine.

[0098] The vulcanizing agent is di-tert-butyl peroxide.

[0099] The polymerization inhibitor is p-hydroxyanisole.

[0100] The preparation method of the composite modified asphalt for the above-mentioned strong and tough synergistic hydraulic asphalt concrete panel leveling layer includes the following steps:

[0101] (1) Take 38 parts by weight of epoxidized castor oil, add 1.0 parts by weight of polymerization inhibitor, and add 60 parts by weight of liquid HDI at 90°C. Stir at 450 r / min for 30 min to generate epoxidized polyurethane. Control the isocyanate index R of the reaction between liquid HDI and epoxidized castor oil to be 1.7.

[0102] (2) The prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, 2.0 parts by mass of chain terminator and 0.3 parts by mass of inhibitor were added in the order of polyurethane-phthalic anhydride-inhibitor-chain terminator and chemically melt-blended, and the composite modified material was prepared by granulation.

[0103] (3) Add 28 parts by weight of the composite modifier and 8 parts by weight of the rubber oil to 65 parts by weight of 90# base asphalt, raise the temperature of the mixture to 180°C, shear at 5500 r / min for 40 min, add 0.4 parts by weight of the vulcanizing agent, keep the temperature at 180°C, stir at 250 r / min for 100 min to swell and develop, and then obtain the composite modified asphalt.

[0104] Example 4

[0105] A composite modified asphalt (4#) for a strong and synergistic leveling layer of hydraulic asphalt concrete panels, which is used as a leveling binder layer for hydraulic asphalt concrete panels, comprises the following components by weight:

[0106]

[0107] The composite modifier is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, and chain terminator.

[0108] in:

[0109] The base asphalt is 90# petroleum asphalt.

[0110] The composite modified material comprises the following components by weight:

[0111]

[0112] The chain terminator is thiobisphenol.

[0113] The vulcanizing agent is dicumyl peroxide.

[0114] The polymerization inhibitor is p-toluenesulfonic acid.

[0115] The preparation method of the composite modified asphalt for the above-mentioned strong and tough synergistic hydraulic asphalt concrete panel leveling layer includes the following steps:

[0116] (1) Take 30 parts by weight of epoxidized castor oil, add 0.5 parts by weight of polymerization inhibitor, and add 65 parts by weight of liquid HDI at 85°C. Stir at 500 r / min for 30 min to generate epoxidized polyurethane. Control the isocyanate index R of the reaction between liquid HDI and epoxidized castor oil to be 1.7.

[0117] (2) The prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, and 1.5 parts by mass of chain terminator were added in the order of polyurethane-phthalic anhydride-chain terminator and chemically melt-blended, and the composite modified product was prepared by granulation.

[0118] (3) Add 22 parts by weight of the composite modifier and 6 parts by weight of the rubber oil to 72 parts by weight of 90# base asphalt, raise the temperature of the mixture to 175°C, shear at 6000 r / min for 45 min, add 0.3 parts by weight of the vulcanizing agent, keep the temperature at 175°C, stir at 300 r / min for 120 min to swell and develop, and then obtain the composite modified asphalt.

[0119] To investigate the strength and toughness of the composite modified asphalt prepared by the above method, the compressive strength of the composite modified asphalt in a normal temperature environment was measured by compression test, and the elongation at break in a low temperature environment was measured by tensile test. The performance of the modified asphalt was evaluated by the two indicators of compressive strength and elongation at break. The test results are shown in Table 1.

[0120] Table 1 shows the properties of the composite modified asphalt obtained in Examples 1-4.

[0121] sample Compressive strength (MPa) Elongation at break (%) viscosity Base asphalt 6.5 10.2 0.55 SBS modified asphalt 12.3 21.5 0.61 1# 16.4 27.1 1.53 2# 15.9 27.6 1.62 3# 16.7 26.8 1.58 4# 15.1 25.8 3.21

[0122] Table 1 shows that the composite modified asphalt exhibits significantly better performance than the most widely used SBS modified asphalt and base asphalt. The incorporation of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor, and chain terminator significantly improves the strength and toughness synergistic properties of asphalt. Asphalt concrete prepared with appropriate gradation shows promise as an ideal leveling and bonding layer material for hydraulic asphalt concrete panels. Example 4, without inhibitors, showed significantly higher viscosity than the other three groups, indicating excessive crosslinking density and high viscosity. Adding inhibitors can further regulate the degree of crosslinking of macromolecular chains, significantly improving its low-temperature fluidity and mixing performance, ensuring the formation of a uniform and dense asphalt film within the mixture.

[0123] This invention involves adding HDI dropwise to epoxidized castor oil with a polymerization inhibitor to generate epoxidized polyurethane. The epoxidized polyurethane, phthalic anhydride, inhibitor, and chain terminator are then granulated into composite particles of a specific size using a granulator, resulting in better compatibility with asphalt. The long chains of epoxidized castor oil and the crosslinking network of HDI effectively help the modified asphalt achieve a synergistic effect of strength and toughness, enhancing the elongation at break and low-temperature crack resistance of the asphalt. Furthermore, controlling the crosslinking density can effectively reduce the viscosity of the modified asphalt, making it less susceptible to solidification due to temperature variations. By using a high polymer content, the synthesized composite modified asphalt is more suitable for preparing asphalt concrete for leveling and bonding layers of hydraulic asphalt concrete panels with a strong, tough, and long service life.

[0124] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A high-strength, synergistic composite modified asphalt for leveling hydraulic panels, characterized in that: The raw materials for the composite modified asphalt are proportioned in the following parts by mass: 65-72 parts of base bitumen 22-28 parts of composite modified material 6-8 parts of rubber oil Vulcanizing agent 0.3~0.4 parts, The raw materials of the composite modifier are proportioned in the following mass parts: Epoxidized castor oil 30-38 parts HDI 55~65 parts Polymerization inhibitor 0.5~1.0 parts, Phthalic anhydride 5-6 parts Chain terminator 1.5~2.0 parts, The inhibitor is 0.2 to 0.3 parts, wherein the inhibitor is at least one selected from BHT (butylated hydroxytoluene), dilauryl thiodipropionate, and diphenylamine; Step 1: Preparation of epoxidized polyurethane: Add 1-3% of polymerization inhibitor to epoxidized castor oil, and add liquid HDI dropwise to the epoxidized castor oil at a temperature of 80-90℃. Stir to generate epoxidized polyurethane. The addition ratio of liquid HDI to epoxidized castor oil is between 1:1.45 and 1:2.

15. The isocyanate index R of the reaction between liquid HDI and epoxidized castor oil is 1.6-1.

8. Step 2: Preparation of composite modified material: Epoxy polyurethane, phthalic anhydride, inhibitor, and chain terminator are added in stages according to the order described above, and then melt-blended by chemical force and granulated to form composite modified material. Step 3: Preparation of composite modified asphalt: The composite modifier and rubber oil are added to the base asphalt, and the vulcanizing agent is slowly added after high-speed shearing. After swelling and development, the composite modified asphalt is obtained.

2. The composite modified asphalt according to claim 1, characterized in that: The base asphalt is at least one of natural asphalt, petroleum asphalt, and coal tar pitch.

3. The composite modified asphalt according to claim 1, characterized in that: The chain terminator is at least one of thiobisphenol, quinone derivatives, and aromatic amines.

4. The composite modified asphalt according to claim 1, characterized in that: The vulcanizing agent is at least one of dicumyl peroxide, sulfur, and di-tert-butyl peroxide.

5. The composite modified asphalt according to claim 1, characterized in that: The polymerization inhibitor is at least one of p-toluenesulfonic acid, dibutyl phthalate, and p-hydroxyanisole.

6. A method for preparing the strong and tough synergistic composite modified asphalt for the hydraulic panel leveling layer according to claim 1, characterized in that, The steps are as follows: Step 1: Preparation of epoxidized polyurethane: Add 1-3% of polymerization inhibitor to epoxidized castor oil, and add liquid HDI dropwise to the epoxidized castor oil at a temperature of 80-90℃. Stir to generate epoxidized polyurethane. The addition ratio of liquid HDI to epoxidized castor oil is between 1:1.45 and 1:2.

15. The isocyanate index R of the reaction between liquid HDI and epoxidized castor oil is 1.6-1.

8. Step 2: Preparation of composite modified material: Epoxy polyurethane, phthalic anhydride, inhibitor, and chain terminator are added in stages according to the order described above, and then melt-blended by chemical force and granulated to form composite modified material. Step 3: Preparation of composite modified asphalt: Composite modified asphalt is prepared by adding composite modifier and rubber oil to base asphalt, followed by high-speed shearing and slow addition of vulcanizing agent, and then allowing it to swell and develop.

7. The preparation method according to claim 6, characterized in that: In step 1, the temperature at which liquid HDI is added is 85°C, and the isocyanate index R of the reaction between liquid HDI and epoxidized castor oil is 1.

7.

8. The preparation method according to claim 6, characterized in that: In step 3, the high-speed shearing speed is 4000-6000 r / min and the shearing time is 30-45 min; the swelling development stirring speed is 200-300 r / min and the stirring time is 90-120 min; the temperature for both high-speed shearing and swelling development is 170-180℃.

9. The application of the composite modified asphalt according to claim 1, characterized in that: A leveling adhesive layer applied to hydraulic asphalt concrete panels.

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