Warm-mixing anti-rutting synergistic interaction type composite modifier and use method thereof

Abstract

The invention relates to the technical field of roads, in particular to a warm-mixing anti-rutting synergistic interaction type composite modifier and a using method thereof.The warm-mixing anti-rutting synergistic interaction type composite modifier is prepared from, by mass, 40-65% of main modified resin, 15-30% of warm-mixing synergist, 10-25% of anti-rutting enhancer and 1-5% of auxiliaries; wherein the main modified resin is ethylene-vinyl acetate and epoxy resin; the warm mixing synergist comprises nano silicon dioxide particles and a surfactant in a mass ratio of (65-85): (15-35); wherein the surfaces of the nano silicon dioxide particles are modified with polyethylene glycol monomethyl ether; the anti-rut reinforcing agent is maleic anhydride grafted polyolefin fiber subjected to gradient modification; the viscosity of the asphalt is reduced through methoxypolyethylene glycol to realize low-temperature construction, and meanwhile, the methoxypolyethylene glycol is molten to permeate the fiber groove; in the service stage, methoxypolyethylene glycol is crystallized and cured to form nano wedge locking fibers, epoxy resin and fiber covalent anchor points cooperatively construct an enhanced network, and the anti-rutting capacity is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of roads, and in particular to a warm-mix anti-rutting synergistic composite modifier and a use method thereof. Background Art

[0002] The use of warm-mix technology in roads can reduce the mixing and compaction temperature of asphalt mixtures, thereby reducing energy consumption and carbon emissions, reducing the emission of harmful gases such as asphalt smoke during construction, improving the construction environment, and at the same time broadening the applicable range of construction temperature to meet construction needs under low temperature conditions; the use of anti-rutting technology can enhance the road's ability to resist plastic deformation, significantly improve the road's durability under repeated vehicle rolling, reduce the maintenance and reconstruction costs caused by rutting diseases, and ensure driving safety and comfort; the coordinated application of warm-mix and anti-rutting technologies will help roads achieve green construction and long-term stable service.

[0003] Currently, the anti-rutting properties of asphalt pavements mainly rely on high modulus agents, polyethylene or rubber powder modifiers. These materials need to be mixed at a high temperature above 160°C. Although they improve the deformation resistance, they aggravate the aging of asphalt, increase energy consumption, and PE is prone to uneven dispersion, causing weak interfaces. Warm mix agents mostly use synthetic wax or zeolite. Although they can achieve construction at 135-145°C, they suffer a significant loss of high-temperature stability and lack self-repairing capabilities during service.

[0004] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a warm-mix anti-rutting synergistic composite modifier and a method for using the same. During the mixing stage, polyethylene glycol monomethyl ether is used to reduce the viscosity of asphalt to achieve low-temperature construction, while the molten polyethylene glycol monomethyl ether penetrates the fiber grooves. During the service stage, the polyethylene glycol monomethyl ether is crystallized and solidified to form nano-wedge locked fibers, and the epoxy resin and the fiber covalent anchor points synergistically construct an enhanced network, significantly improving the anti-rutting ability, thereby achieving the purpose of warm-mix anti-rutting synergistic enhancement.

[0006] The first object of the present invention is to provide a warm-mix anti-rutting synergistic composite modifier, which comprises, by mass percentage, 40-65% of a main modified resin, 15-30% of a warm-mix synergist, 10-25% of an anti-rutting enhancer, and 1-5% of an additive;

[0007] Among them, the main modified resins are ethylene vinyl acetate and epoxy resin;

[0008] The main modified resin accounts for a high proportion, and is a core component of the composite modifier, wherein the ethylene-vinyl acetate and the epoxy resin can be melted to form a low-viscosity carrier at high temperature, rapidly wrap aggregate and penetrate into bitumen paste, and also can activate the amine group on the surface of the anti-rutting reinforcing agent, initiate the ring-opening reaction of the epoxy, form a firm covalent bond anchor point at the interface of the fiber and the bitumen, and lay a foundation for constructing a space network support system against rutting;

[0009] The warm-mixing synergist comprises nano-silicon dioxide particles and a surfactant in a mass ratio of 65-85:15-35, wherein the nano-silicon dioxide particles are surface-modified by polyethylene glycol monomethyl ether;

[0010] The anti-rutting reinforcing agent is a maleic anhydride grafted polyolefin fiber which is gradient-modified.

[0011] 10-25% of the anti-rutting reinforcing agent is a polyolefin fiber which is treated by a multi-stage amine functionalization, and the amount thereof can ensure that a stable space network support system is formed in the bitumen mixture, directly share the shear stress borne by the skeleton aggregate, and avoid affecting the construction and road performance of the mixture due to too much fiber;

[0012] In use, in the bitumen mixture mixing stage, the melted main modified resin wraps the aggregate to form a low-viscosity bitumen paste, and at the same time, the maleic anhydride functional group on the surface of the gradient-modified polyolefin fiber is activated at high temperature, the ring-opening reaction of the epoxy resin is triggered, and the β-hydroxy tertiary amine covalent anchor point is generated, so that a fiber-bitumen chemical bonding network is preliminarily constructed; at this time, the nano-silicon dioxide modified by polyethylene glycol monomethyl ether releases a flexible long chain, is embedded into the bitumen colloid structure to weaken the intermolecular force, and significantly reduces the viscosity of the system to realize warm-mixing construction; the polyethylene glycol monomethyl ether molecules in the molten state migrate in the bitumen medium and penetrate into the surface grooves of the fiber by relying on the polarity of the terminal hydroxyl group;

[0013] In the service stage, the polyethylene glycol monomethyl ether which penetrates into the surface grooves is crystallized and solidified as a hard nano wedge to mechanically lock the fiber displacement; at the same time, the epoxy resin continuously crosslinks and solidifies, and cooperates with the covalent anchor point to strengthen the fiber space network, so that the fiber directly shares the shear stress of the aggregate skeleton, and significantly inhibits the plastic flow of the bitumen mixture;

[0014] And a dynamic hydrogen bond network of the hydroxyl group of the polyethylene glycol monomethyl ether, the carboxyl group of the bitumen and the amide bond of the fiber is formed at the three-phase interface (the aggregate phase, the bitumen paste phase and the anti-rutting reinforcing agent phase), the vehicle load energy is dissipated through bonding reconstruction, and self-repair of micro-cracks is realized, so that the unification of low-temperature construction energy saving and long-term anti-rutting performance is finally achieved.

[0015] Preferably, the auxiliary agent comprises a low-melting-point wax, a dispersant and a stabilizer;

[0016] The dispersant is oleic acid amide;

[0017] The stabilizer is nano-titanium dioxide coated with stearic acid on the surface;

[0018] 1-5% of the auxiliary agent can adjust the interfacial compatibility between the components of the composite modifier of the application, and ensure the realization of the synergistic effect of warm mixing and anti-rutting.

[0019] As a preferred scheme of the application, the method for gradient modification comprises:

[0020] The surface of the polyolefin fiber is etched using a 5-8% NaOH solution to form etched fibers with grooves; more specifically, through alkaline etching, a micro-groove structure is constructed on the surface of the fiber, increasing the specific surface area of the fiber, providing more active sites for subsequent reactions, and also facilitating the formation of mechanical interlocking with other components in the asphalt mixture, laying the foundation for the construction of a fiber and asphalt chemical bonding network.

[0021] The etched fiber is melt-blended with maleic anhydride and a free radical initiator is added, and grafting is carried out at 130-160°C to obtain grafted fibers; more specifically, the free radical initiator in this process promotes the grafting of maleic anhydride onto the surface of the etched fiber, introducing maleic anhydride functional groups that can be activated at high temperatures during the mixing stage of the asphalt mixture, triggering a reaction with epoxy resin to generate beta-hydroxy tertiary amine covalent anchor points, and initially constructing a fiber and asphalt chemical bonding network.

[0022] The grafted fiber is reacted with a polyamine compound at a mass ratio of 100:8-12 at 90-110°C, and after washing and drying, an anti-rutting enhancer is obtained; more specifically, this step causes the maleic anhydride functional groups on the grafted fiber to react with the polyamine compound, producing new active amine groups on the surface of the fiber, which react with epoxy resin to form covalent anchor points, while enhancing the interaction between the fiber and the asphalt, crosslinking and curing with the epoxy resin during the service stage to synergistically strengthen the fiber spatial network and enhance the anti-rutting performance.

[0023] As a preferred embodiment of the present invention, the polyamine compound is at least one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine; more specifically, when reacting with the grafted fiber, the amino group of the polyamine compound can fully undergo an aminolysis reaction with the carboxylic anhydride group on the maleic anhydride grafted chain segment, and a large number of active amine groups are introduced to the fiber surface. These active amine groups can efficiently react with the epoxy resin to generate β-hydroxy tertiary amine covalent anchor points during the asphalt mixture mixing stage, thereby accelerating the initial construction of the fiber asphalt chemical bonding network; during the service stage, it helps the epoxy resin to continuously cross-link and cure, further strengthen the fiber space network, enable the fiber to more effectively share the aggregate skeleton shear stress, and inhibit the plastic flow of the asphalt mixture; at the same time, the amino group introduced by the polyamine compound can also participate in the formation of a dynamic hydrogen bond network at the three-phase interface, interact with the hydroxyl group of polyethylene glycol monomethyl ether and the carboxyl group of asphalt, dissipate vehicle load energy through bonding reconstruction, assist in the self-repair of microcracks, and synergistically improve low-temperature construction energy saving and long-term anti-rutting performance.

[0024] As a preferred embodiment of the present invention, the free radical initiator is dicumyl peroxide, added in an amount of 0.5-1.2% by weight of maleic anhydride. More specifically, dicumyl peroxide can stably decompose to produce free radicals at 130-160°C. An appropriate amount of free radicals can effectively initiate the opening of double bonds in maleic anhydride, allowing it to be smoothly grafted onto the etched polyolefin fiber surface, introducing maleic anhydride functional groups. The addition of 0.5-1.2% ensures a sufficient grafting reaction while avoiding increased side reactions and performance degradation caused by excessive initiator, thereby ensuring that the fiber will subsequently crosslink and cure with the epoxy resin to synergistically strengthen the fiber spatial network during service.

[0025] As a preferred embodiment of the present invention, the polyolefin fiber is at least one of isotactic polypropylene fiber, polyethylene fiber, and ethylene-propylene copolymer fiber. More specifically, the polyolefin fiber is compatible with the grafting temperature and has excellent chemical stability and mechanical properties, capable of maintaining structural integrity under high-temperature mixing and long-term service conditions of asphalt mixtures.

[0026] As a preferred embodiment of the present invention, the epoxy resin is bisphenol A epoxy resin;

[0027] The mass ratio of ethylene vinyl acetate (EVA) to epoxy resin is 15-28:72-85.

[0028] More specifically, the molecular structure of bisphenol A epoxy resin contains two epoxy groups. During the high-temperature mixing stage of the asphalt mixture, they can fully react with the active amine groups on the surface of the anti-rutting enhancer to efficiently generate β-hydroxy tertiary amine covalent anchor points, rapidly building a fiber-asphalt chemical bonding network. Furthermore, during the service phase, they can continuously crosslink and cure, synergizing with the covalent anchor points to further strengthen the fiber spatial network and enhance the inhibitory effect on the plastic flow of the asphalt mixture.

[0029] Controlling the mass ratio of ethylene vinyl acetate and epoxy resin at 15-28:72-85 can not only ensure that the molten EVA quickly wraps the aggregate during the mixing stage of the asphalt mixture to form a low-viscosity asphalt mortar, reduce the initial viscosity of the system, and facilitate warm mix construction; but also ensure that there is a sufficient proportion of epoxy resin to react with the anti-rutting enhancer to build a stable chemical bonding network.

[0030] As a preferred embodiment of the present invention, a method for modifying the surface of nano-silica particles with polyethylene glycol monomethyl ether comprises:

[0031] (1) Nano-silica and a silane coupling agent are dispersed in toluene at a mass ratio of 1:0.15-0.25, refluxed at 110±5°C for 2-5 hours, and centrifuged to obtain epoxylated SiO2; more specifically, KH560 is selected as the silane coupling agent. During the above process, the alkoxy groups of the silane coupling agent react with the hydroxyl groups on the surface of the silica to introduce epoxy groups on the surface to form epoxylated SiO2, which provides active sites for the subsequent grafting reaction;

[0032] (2) Epoxy-SiO2 and polyethylene glycol monomethyl ether are mixed in a mass ratio of 1:1.2 to 1.5, triethylamine is added, and the mixture is reacted at 85±5°C for 5-15 hours. More specifically, in the above process, triethylamine is used as a catalyst. At 85±5°C, the terminal hydroxyl group of polyethylene glycol monomethyl ether attacks the epoxy group to cause a ring-opening reaction, thereby grafting the epoxy group to the surface of the nano-silica in the form of a covalent bond to form a flexible long-chain structure.

[0033] (3) After washing with ethanol, vacuum drying is performed at 40-60°C to obtain a grafted product; more specifically, unreacted polyethylene glycol monomethyl ether and triethylamine are removed by washing with ethanol, and under vacuum drying conditions at 40-60°C, thermal decomposition of polyethylene glycol monomethyl ether is avoided and residual solvent is completely removed, thereby obtaining nano-silica with polyethylene glycol monomethyl ether uniformly grafted on the surface. Nano-silica can achieve warm mixing in asphalt by weakening the intermolecular forces of asphalt through flexible chain segments, and improve the anti-rutting performance during the service stage by crystallizing and interlocking fibers and forming a dynamic hydrogen bond network.

[0034] As a preferred embodiment of the present invention, the particle size of the nano-silica particles is 15-20 nm, the molecular weight of polyethylene glycol monomethyl ether is 6000-9000 Da, and the triethylamine is 0.8-1.2% of the mass of the polyethylene glycol monomethyl ether. More specifically, the above particle size range ensures that the nano-silica has good dispersibility in the asphalt system, which can fully utilize the small size effect of the nanomaterial to make the particles uniformly distributed in the asphalt colloidal structure, while avoiding the agglomeration phenomenon caused by the small particle size that affects the modification effect.

[0035] The polyethylene glycol monomethyl ether in the above molecular weight range has a moderate chain length. During the asphalt mixture mixing stage, it can provide sufficient flexibility to weaken the intermolecular forces of asphalt, significantly reducing the viscosity of the system to achieve warm mix construction, and can also ensure that the terminal hydroxyl groups can effectively participate in the formation of a dynamic hydrogen bond network at the three-phase interface during service.

[0036] Triethylamine is used as a catalyst. The added amount can effectively promote the ring-opening reaction between the hydroxyl groups of polyethylene glycol monomethyl ether and the epoxy groups on the surface of epoxylated silica to ensure the full progress of the grafting reaction, while avoiding the increase of side reactions or the introduction of excessive impurities due to excessive catalyst.

[0037] As a preferred embodiment of the present invention, the surfactant is a mixture of stearic acid monoglyceride and Tween.

[0038] More specifically, the mass ratio of the two is 1-5:1-4. Stearic acid monoglyceride can reduce the interfacial tension between asphalt and aggregate, improve the asphalt wrapping, provide lubrication at high temperature, and cooperate with polyethylene glycol monomethyl ether to reduce the viscosity of the mixture and promote warm mixing; Tween enhances the dispersion stability of nano-silica, prevents agglomeration, and promotes the compatibility of various components, assists the dynamic hydrogen bond network, dissipates load energy, realizes self-repair of microcracks, and improves the rutting resistance and durability of the road surface.

[0039] A second object of the present invention is to provide a method for using a warm-mix anti-rutting synergistic composite modifier, comprising:

[0040] S1 adds a composite modifier, accounting for 5-8% of the asphalt mass, to a base asphalt at 160-170°C and mixes to form a modified asphalt mortar. More specifically, under high-temperature mixing, ethylene-vinyl acetate melts and disperses to form a low-viscosity carrier that encapsulates the epoxy resin, significantly reducing the overall viscosity of the base asphalt and improving its fluidity. Simultaneously, high temperature activates the surface anhydride functional groups of the anti-rutting enhancer and triggers the ring-opening of the epoxy resin to react with its newly formed surface amine groups, initially constructing covalent anchor points of β-hydroxy tertiary amines between the fiber, epoxy, and asphalt, laying the foundation for chemical bonding in the subsequent spatial network.

[0041] S2: Aggregates preheated to 140-150°C are mixed with modified asphalt mortar, and dry and wet mixed at 135-145°C to obtain an asphalt mixture. More specifically, the nano-silica modified with polyethylene glycol monomethyl ether releases flexible long chains at the warm mixing temperature, and synergistically with surfactants to significantly weaken the intermolecular forces of asphalt, reducing the viscosity of the system to a level that can be constructed at 135-145°C. At the same time, the molten polyethylene glycol monomethyl ether molecules migrate in the asphalt medium and directional penetrate into the surface grooves of the polyolefin fiber through the polarity of the terminal hydroxyl groups. Dry mixing ensures that the aggregate is evenly coated with the modified asphalt mortar, while wet mixing allows the mineral powder to fill the voids to form a homogeneous mixture.

[0042] S3 asphalt mixture is paved at ≥125℃, initially compacted at 120-130℃, and finally compacted at ≥90℃. More specifically, within the compaction temperature range, on the one hand, it ensures that polyethylene glycol monomethyl ether remains in a molten state to complete the final penetration and fiber interlocking preparation, and on the other hand, it promotes the cross-linking and curing of epoxy resin and the strengthening of covalent anchor points. The external force of rolling causes the anti-rutting enhancer to be evenly dispersed and directionally arranged in the mixture. After the final compaction, natural cooling will induce the crystallization and solidification of polyethylene glycol monomethyl ether into nano-wedge mechanically interlocked fibers, and drive the final formation of the epoxy covalent network and dynamic hydrogen bond network, giving the road surface immediate and gradually enhanced anti-rutting and self-repairing capabilities.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The composite modifier of the present invention releases flexible chain segments through polyethylene glycol monomethyl ether modified nano-silica to cooperate with surfactants, significantly reducing asphalt viscosity and lowering the mixing temperature to 135-145°C, greatly reducing energy consumption and emissions; simultaneously, the main modified resin is used to melt-wrap the aggregate to form a low-viscosity slurry, combined with the directional penetration channel of the gradient modified fiber, to ensure the uniformity of the mixture and smooth construction under low temperature conditions;

[0045] (2) During the service phase, the polyethylene glycol monomethyl ether that penetrates into the fiber grooves crystallizes and solidifies into nano-wedges to mechanically lock the fiber displacement; the epoxy resin and the β-hydroxy tertiary amine covalent anchor points on the fiber surface are cross-linked and solidified to construct a spatial network; the gradient modified polyolefin fiber directly shares the aggregate shear stress. The three work together to greatly improve the deformation resistance and significantly inhibit the plastic flow and rutting formation of the pavement.

[0046] (3) The hydroxyl groups of polyethylene glycol monomethyl ether, asphalt carboxyl groups and fiber amide bonds at the three-phase interface form a dynamic hydrogen bond network, which dissipates vehicle load energy through reversible bond breaking and reorganization, achieving self-repair of microcracks. The continuous cross-linking and curing of epoxy resin enhances the road surface's rutting resistance over time. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention is a schematic flow chart of a method for using the warm-mix anti-rutting synergistic composite modifier. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0049] The sources of materials used in the following examples and comparative examples are as follows:

[0050] Ethylene vinyl acetate: Mitsui Chemicals, Japan;

[0051] Bisphenol A epoxy resin: Shandong Tianmai Chemical Co., Ltd.

[0052] Nano-silica particles: Henan Haiborui Silicon Material Technology Co., Ltd.;

[0053] Polyethylene glycol monomethyl ether: Sundar Chemical (Nantong) Co., Ltd.

[0054] Silane coupling agent (KH560): Heshan Jinrunna New Materials Co., Ltd.

[0055] Stearic acid monoglyceride: Guangzhou Jiadele Biochemical Technology Co., Ltd.;

[0056] Twain: Shanghai Yuanye Biotechnology Co., Ltd.;

[0057] Maleic anhydride: Jiangsu Sanmu Group Co., Ltd.

[0058] Dicumyl peroxide: Qingdao Haida Chemical Co., Ltd.

[0059] Diethylenetriamine: Tosoh, Japan;

[0060] Polypropylene / ethylene fiber: Jiangsu Haiyang Chemical Fiber Co., Ltd.

[0061] Oleamide: Jinan Zhengkang Chemical Co., Ltd.

[0062] Stearic acid-coated nano-titanium dioxide: Hangzhou Hengna New Materials Co., Ltd.

[0063] Example 1:

[0064] The composite modifier of the present invention comprises:

[0065] The composite modifier consists of 55% main modifying resin, 25% warm-mix synergist, 18% anti-rutting enhancer, and 2% additives, calculated by mass percentage. The main modifying resin is ethylene vinyl acetate and bisphenol A epoxy resin, with a mass ratio of 20:80. The warm-mix synergist comprises modified nano-silica particles and a surfactant in a mass ratio of 75:25. The nano-silica particles are 15-20 nm in size and surface-modified with polyethylene glycol monomethyl ether (PEG) with a molecular weight of 8,000 Da. The surfactant is a mixture of stearic acid monoglyceride and polysorbate (Tween) in a mass ratio of 3:2. The anti-rutting enhancer is made from isotactic polypropylene fibers via gradient modification. The additives consist of low-melting-point wax, oleamide, and nano-titanium dioxide coated with stearic acid in random proportions.

[0066] The preparation method of modified nano-silica particles is as follows:

[0067] Nano-silica and silane coupling agent (KH560) were dispersed in toluene at a mass ratio of 1:0.2, refluxed at 110°C for 3 h, and centrifuged after the reaction to obtain epoxy-SiO2.

[0068] Then, epoxylated SiO2 and polyethylene glycol monomethyl ether were mixed in a mass ratio of 1:1.3, and triethylamine with a mass ratio of 1% of polyethylene glycol monomethyl ether was added, and the mixture was reacted at 85°C for 10 hours. After the reaction was completed, the mixture was washed with ethanol and dried in vacuum at 50°C to obtain nano-silica particles with surface modified with polyethylene glycol monomethyl ether.

[0069] The preparation method of the anti-rutting enhancer is as follows:

[0070] Immerse isotactic polypropylene fibers in a 6% NaOH solution at room temperature for 2 hours, then rinse repeatedly with clean water until neutral, and vacuum dry to obtain etched fibers with grooves.

[0071] The etched fiber and maleic anhydride were melt-blended at a mass ratio of 1:0.15, and dicumyl peroxide (1% by mass of maleic anhydride) was added as a free radical initiator. The mixture was reacted at 150°C for 1.5 hours to obtain a grafted fiber.

[0072] The grafted fiber and diethylenetriamine were reacted at a mass ratio of 100:10 at 100°C for 2 hours. After the reaction, the fiber was washed with ethanol and dried in a vacuum at 60°C to obtain an anti-rutting enhancer.

[0073] The method for using the warm-mix anti-rutting synergistic composite modifier includes:

[0074] S1: Heat the base asphalt to 165°C, add the above-mentioned composite modifier accounting for 6% of the asphalt mass, and shear at 800 rpm for 20 minutes to uniformly disperse the composite modifier in the asphalt to form a modified asphalt mortar;

[0075] S2: preheat the aggregate to 145°C, add the modified asphalt mortar, dry mix for 15 seconds and then wet mix for 45 seconds at 140°C to fully coat the aggregate with the asphalt to obtain an asphalt mixture;

[0076] S3 spreads the asphalt mixture at a temperature of 130°C, then performs initial compaction at 125°C, using a double steel wheel roller for two static compactions; then performs final compaction at a temperature not lower than 95°C, using a rubber wheel roller for three compactions, until the road surface is smooth and dense.

[0077] Example 2: The difference from Example 1 is that:

[0078] The warm-mix anti-rutting synergistic composite modifier of the present invention is specifically composed of: 49% main modified resin, 30% warm-mix synergist, 20% anti-rutting enhancer and 1% auxiliary agent in terms of mass percentage;

[0079] Example 3: The difference from Example 1 is that:

[0080] The warm-mix anti-rutting synergistic composite modifier of the application, by mass percentage, the specific composition of the composite modifier is: 55% main modified resin, 25% warm-mix synergist, 19% anti-rutting enhancer and 1% auxiliary agent.

[0081] Example 4: Different from example 1 is:

[0082] The anti-rutting enhancer is a gradient-modified maleic anhydride grafted polyolefin fiber, the polyolefin fiber is selected as an ultrahigh molecular weight polyethylene fiber, and the specific preparation method is:

[0083] The ultrahigh molecular weight polyethylene fiber is immersed in a NaOH solution with a concentration of 8%, treated at room temperature for 2.5h, washed repeatedly with water to neutral after taking out, and vacuum dried to obtain etched fibers with grooves;

[0084] The etched fibers are melt-blended with maleic anhydride at a mass ratio of 1:0.18, 1% of dicumyl peroxide is added as a free radical initiator, and the reaction is carried out at 132℃ for 1.5h to obtain grafted fibers;

[0085] The grafted fibers are reacted with diethylenetriamine at a mass ratio of 100:9 at 100℃ for 2h, washed with ethanol after the reaction is completed, and vacuum dried at 60℃ to obtain the anti-rutting enhancer.

[0086] Comparative example 1:

[0087] Different from example 1 is that the nano-silicon dioxide particles in the warm-mix synergist are not modified by polyethylene glycol monomethyl ether.

[0088] Comparative example 2:

[0089] Different from example 1 is that the anti-rutting enhancer uses isotactic polypropylene fibers without gradient modification treatment.

[0090] Comparative example 3:

[0091] Different from example 1 is that the main modified resin only uses ethylene-vinyl acetate (EVA), and the bisphenol A type epoxy resin is removed, EVA accounts for 100% of the mass of the main modified resin, and the remaining components are consistent with example 1.

[0092] Comparative example 4:

[0093] Different from example 1 is that in the preparation process of the anti-rutting enhancer, the NaOH etching step of the polypropylene fiber is omitted, and the polypropylene fiber is directly melt-blended and grafted with maleic anhydride, and the subsequent steps remain unchanged, and the remaining components are consistent with example 1.

[0094] Comparative example 5:

[0095] The difference from Example 1 is that in the preparation of the anti-rutting enhancer, diethylenetriamine is replaced by butylamine (monoprimary amine, non-polyamine compound), and the rest is the same as Example 1.

[0096] The following tests were performed on the examples and comparative examples:

[0097] Dynamic stability: Refer to the test method of "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2011) T0719 and use a rutting test machine for testing.

[0098] The modified asphalt mixture was made into 300mm×300mm×50mm rutting plate specimens. The specimens were tested at 60°C with a load of 0.7MPa and a reciprocating rolling method. The deformation curve of the specimens was recorded over time.

[0099] Calculate dynamic stability according to the formula: DS = 42000 / (d 60 -d 45 ), where d 60 and d 45 The deformation at 45min and 60min respectively.

[0100] Microcrack self-healing efficiency: 400 mm × 50 mm × 6 mm prismatic specimens were prepared and loaded with a 10 Hz sine wave on an MTS fatigue testing machine until the crack length Δa0 = 2 mm. The specimens were then kept at a constant temperature of 25°C for 24 h, during which the crack closure was observed using SEM.

[0101] Asphalt mixture mixing temperature reduction value: According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", prepare a base asphalt mixture without adding a modifier and a modified asphalt mixture prepared according to the examples and comparative examples, respectively. Keep the two mixtures to achieve the same paving and workability, and record the difference between the minimum mixing temperature of the base asphalt mixture and the minimum mixing temperature of the modified asphalt mixture with the modifier of the present invention.

[0102] After the above tests were carried out on the embodiments and comparative examples, the data in Table 1 were obtained;

[0103] Table 1 Test results of the embodiments and comparative examples

[0104]

[0105] In the examples, polyethylene glycol monomethyl ether-modified nanosilica, combined with surfactants, significantly reduces asphalt viscosity, achieving a 16-18°C drop in mixing temperature and reducing energy consumption. The primary modified resin and gradient-modified fiber ensure uniformity of the mixture at low temperatures. During service, the crystallization and curing of polyethylene glycol monomethyl ether, the cross-linking of the epoxy resin, and the fiber synergize to achieve a dynamic stability of 8,800-9,500 times / mm, significantly reducing rutting. The dynamic hydrogen bond network at the three-phase interface achieves a microcrack self-healing efficiency of 62%-68%, and the continuous curing of the epoxy resin further enhances anti-rutting performance.

[0106] Comparative Example 1: Nano-silica without modification of polyethylene glycol monomethyl ether cannot release flexible chain segments to reduce the viscosity of asphalt mixture, resulting in a mixing temperature drop of only 8°C; at the same time, the lack of nano-wedges formed by the crystallization of polyethylene glycol monomethyl ether cannot mechanically lock the displacement of polyolefin fibers, and the dynamic stability drops to 5200 times / mm; and the nano-silica surface has insufficient hydroxyl groups, making it difficult to participate in the formation of a dynamic hydrogen bond network at the three-phase interface, and the micro-crack self-repair efficiency is only 25%.

[0107] Comparative Example 2: The surface of the unmodified polypropylene fiber has no active amino groups and cannot undergo epoxy ring-opening reaction with the epoxy resin in the main modified resin, resulting in the loss of covalent bond anchor points of β-hydroxy tertiary amine. The fiber cannot form an effective support network, and the dynamic stability drops to 4800 times / mm; at the same time, due to the lack of amino group participation, the hydrogen bond density at the three-phase interface is greatly reduced, and the self-repair efficiency of microcracks is only 20%.

[0108] Comparative Example 3: After the epoxy resin is removed from the main modified resin, it cannot undergo a ring-opening reaction with the amino groups on the surface of the polyolefin fiber, the fiber-asphalt interface loses its covalent bond anchoring effect, the spatial network support system fails, the anti-rutting performance is significantly reduced, and the dynamic stability is only 5500 times / mm; in addition, the lack of the epoxy resin cross-linking effect weakens the bonding force of the three-phase interface, and the microcrack self-repair efficiency is only 28%.

[0109] Comparative Example 4: The etching step of the polyolefin fiber is omitted, resulting in a surface without a groove structure, making it difficult for the molten polyethylene glycol monomethyl ether to penetrate deeply and crystallize to form nanowedges. The fiber is easy to slide in the asphalt, and the dynamic stability is reduced to 5000 times / mm; and the lack of etching leads to a decrease in the specific surface area of ​​the fiber, weakening the synergistic dispersion effect with nano-silica, and the self-repair efficiency of microcracks is only 22%.

[0110] Comparative Example 5: Using monoprimary amine (butylamine) instead of polyamine compounds cannot achieve multi-level amine functionalization on the fiber surface, and only forms a single layer of amine groups, resulting in a significant reduction in the number of covalent bond anchor points, a significant decrease in the interface strength between the fiber and asphalt, and a dynamic stability as low as 4500 times / mm; at the same time, the hydrogen bond network formed by the monoprimary amine is not stable enough, and it is difficult to achieve microcrack self-repair through reversible bond breaking and recombination, with an efficiency of only 18%.

[0111] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A warm mix anti-rutting synergistic composite modifier, characterized in that: Calculated by mass percentage, it includes: 40-65% main modified resin, 15-30% warm mix synergist, 10-25% anti-rutting enhancer and 1-5% additive; Among them, the main modified resins are ethylene vinyl acetate and epoxy resin; The warm mix synergist comprises nano-silica particles and a surfactant in a mass ratio of 65-85:15-35; wherein the surface of the nano-silica particles is modified with polyethylene glycol monomethyl ether; The anti-rutting enhancer is gradient-modified maleic anhydride grafted polyolefin fiber.

2. The warm-mix anti-rutting synergistic composite modifier according to claim 1, characterized in that: The gradient modification method comprises: The surface of the polyolefin fiber is etched using a 5-8% NaOH solution to form an etched fiber with grooves; The etched fiber is melt-blended with maleic anhydride, and a free radical initiator is added, and grafting is performed at 130-160° C. to obtain a grafted fiber; The grafted fiber is reacted with a polyamine compound at 90-110 DEG C, and the anti-rutting enhancer is prepared after washing and drying.

3. The warm-mix anti-rutting synergistic composite modifier according to claim 2, characterized in that: The polyamine compound is at least one of diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

4. The warm-mix anti-rutting synergistic composite modifier according to claim 2, characterized in that: The free radical initiator is dicumyl peroxide, and the added amount is 0.5-1.2% of the mass of maleic anhydride.

5. The warm-mix anti-rutting synergistic composite modifier according to claim 2, characterized in that: The polyolefin fiber is at least one of isotactic polypropylene fiber, polyethylene fiber and ethylene-propylene copolymer fiber.

6. The warm-mix anti-rutting synergistic composite modifier according to claim 1, characterized in that: The epoxy resin is bisphenol A epoxy resin; The mass ratio of the ethylene vinyl acetate to the epoxy resin is 15-28:72-85.

7. The warm-mix anti-rutting synergistic composite modifier according to claim 1, characterized in that: The method for modifying the surface of nano-silica particles with polyethylene glycol monomethyl ether comprises: (1) Disperse nano-silica and silane coupling agent in toluene at a mass ratio of 1:0.15-0.25, reflux at 110±5℃ for 2-5h, and centrifuge to obtain epoxy-SiO2; (2) Mix epoxylated SiO2 and polyethylene glycol monomethyl ether in a mass ratio of 1:1.2~1.5, add triethylamine, and react at 85±5℃ for 5-15h; (3) After washing with ethanol, vacuum drying was performed at 40-60°C to obtain the grafted product.

8. The warm-mix anti-rutting synergistic composite modifier according to claim 7, characterized in that: The particle size of the nano-silica particles is 15-20 nm, the molecular weight of polyethylene glycol monomethyl ether is 6000-9000 Da, and the content of triethylamine is 0.8-1.2% of the mass of the polyethylene glycol monomethyl ether.

9. The warm-mix anti-rutting synergistic composite modifier according to claim 1, characterized in that: The surfactant is a mixture of stearic acid monoglyceride and Tween.

10. A method for using a warm-mix anti-rutting synergistic composite modifier, characterized in that: include: Adding 5-8% of the composite modifier by weight of the asphalt into the base asphalt at 160-170°C, mixing to form a modified asphalt mortar; Mixing the aggregate preheated to 140-150° C. and the modified asphalt mortar, and dry-mixing and wet-mixing at 135-145° C. to obtain an asphalt mixture; The asphalt mixture is paved at ≥125°C, initially compacted at 120-130°C, and finally compacted at ≥90°C.

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