Environment-friendly warm mix asphalt regenerant and preparation method thereof

Abstract

The invention provides an environment-friendly warm mix asphalt regenerant and a preparation method thereof, and relates to the technical field of road engineering materials, and the environment-friendly warm mix asphalt regenerant comprises 20-30% of a high-molecular polymer which is polyvinyl alcohol; 5-10% of a surfactant, which is polyoxyethylene ether; the nano composite material is a graphene / carbon nano tube composite material, and the mass ratio of graphene to carbon nano tubes is 2: 1; 0.5-3% of an antioxidant, which is butyl hydroxy anisd; 5-15% of a multifunctional modified additive which is a compound of nano silicon powder and sulfide, the nano silicon powder accounts for 80%, and the sulfide accounts for 20%; 0-5% of a green and environment-friendly component which is polylactic acid; and 0-5% of a solvent which is a terpene solvent. According to the environment-friendly warm mix asphalt regenerant and the preparation method thereof, organic combination of high performance and low carbon emission is realized; and the polyurethane self-repairing component endows the regenerant with micro-crack automatic closing capability in the warm mixing or service period, so that the long-term stability is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering materials, in particular to an environmentally friendly warm mix asphalt regenerator and a preparation method thereof. Background Art

[0002] Currently, asphalt concrete is widely used in road construction. With increasing traffic volume and the extension of road service life, the aging problem of road surfaces has gradually become apparent. As asphalt ages, its physical and chemical properties significantly deteriorate, especially its crack resistance, aging resistance, and resistance to water damage, which seriously affect the service life of the road and traffic safety. To address this problem, the use of recycled asphalt materials has gradually become an important means of road repair and maintenance. Existing recycled asphalt technology mainly improves its performance by mixing discarded asphalt with new asphalt. The core of this method lies in the addition of regeneration agents, which adjust the physical properties of the asphalt to restore its original crack resistance and aging resistance. The types and effects of regeneration agents vary. Among them, the common warm-mix asphalt regeneration agent has become a mainstream technology by lowering the mixing temperature of asphalt, reducing energy consumption, and improving environmental friendliness. Warm-mix asphalt technology not only reduces the temperature but also effectively reduces the impact of temperature fluctuations on asphalt performance, providing support for low-carbon and green construction.

[0003] The biggest drawback of existing warm-mix asphalt rejuvenators is their unstable performance. In particular, their ability to bind to asphalt can lead to a decrease in effectiveness after repeated heating and prolonged use, rendering them ineffective in restoring the properties of aged asphalt. This fluctuating performance not only impacts the lifespan of roads but can also increase ongoing maintenance costs. Therefore, there is an urgent need for a new warm-mix asphalt rejuvenator that not only improves asphalt regeneration performance but also maintains long-term stability, ensuring the long-term safety of road structures. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides an environmentally friendly warm mix asphalt regeneration agent and a preparation method thereof. The technical problem to be solved by the invention is: how to improve the stability of the performance of the existing warm mix asphalt regeneration agent.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: an environmentally friendly warm mix asphalt regeneration agent, comprising:

[0006] High molecular weight polymer: 20-30%, polyvinyl alcohol;

[0007] Surfactant: 5-10%, which is polyoxyethylene ether;

[0008] Nanocomposite material: 1-5%, graphene / carbon nanotube composite material, wherein the mass ratio of graphene to carbon nanotube is 2:1;

[0009] Antioxidant: 0.5-3%, butylated hydroxyanisole;

[0010] Multifunctional modification additive: 5-15%, which is a composite of nano-silicon powder and sulfide, wherein the nano-silicon powder accounts for 80% and the sulfide accounts for 20%;

[0011] Green and environmentally friendly ingredients: 0-5%, polylactic acid;

[0012] Solvent: 0-5%, terpene solvent.

[0013] Preferably, the terpene solvent includes lemon oil, orange peel oil or peppermint oil, which can help adjust the fluidity of the regeneration agent and ensure its uniform dispersion in the asphalt.

[0014] Preferably, the molecular weight of the high molecular weight polymer polyvinyl alcohol is 5000-10000, and the molecular weight of the surfactant polyoxyethylene ether is 1500-3000.

[0015] A method for preparing an environmentally friendly warm mix asphalt regeneration agent comprises the following steps:

[0016] S1. The polymer polyvinyl alcohol, the surfactant polyoxyethylene ether, the nanocomposite graphene / carbon nanotube composite material, the antioxidant butylated hydroxyanisole, the multifunctional modifying additive nanosilicon powder and sulfide complex, the green and environmentally friendly ingredient polylactic acid, and the solvent terpene solvent are mixed uniformly in a mass ratio to form a uniform raw material mixture;

[0017] S2. The raw material mixture is heated to 110°C to 130°C and stirred continuously at this temperature for 3-4 hours to ensure that the components are fully reacted and a uniform regeneration agent formula is formed. The temperature is controlled with an accuracy of ±2°C.

[0018] S3 continues heating and maintaining the temperature until the solvent is completely evaporated to obtain a solid regeneration agent formulation, wherein the water content of the solid regeneration agent formulation does not exceed 1%;

[0019] S4. The resulting solid regeneration agent formulation is cooled to room temperature and the particle size is adjusted to 10-50 μm by grinding or sieving;

[0020] S5. Continue stirring the cooled regeneration agent and add an appropriate amount of polyurethane material to enhance the self-repairing function of the regeneration agent, allowing it to automatically repair microcracks during heating or use, thereby improving its long-term stability;

[0021] S6. Mix the resulting regeneration agent with asphalt in a mass ratio of 1:10 to 1:20 and perform a warm mixing operation at 120°C to 140°C to ensure uniform dispersion and full integration of the regeneration agent in the asphalt;

[0022] S7. Cooling the final mixed asphalt rejuvenator to room temperature to obtain a warm mix asphalt rejuvenator with good thermal stability, aging resistance, crack resistance and environmental friendliness, which is used for road construction and maintenance.

[0023] Preferably, the surfactant polyoxyethylene ether has a molecular weight of 2000-2500 and a surface tension of less than 40 mN / m, which can effectively promote the uniform dispersion of the regeneration agent and the aged asphalt and avoid sedimentation or stratification.

[0024] Preferably, the addition amount of the polyurethane material in S5 is 1-3%, the polyurethane material is a polyurethane prepolymer, the polyurethane prepolymer is a reaction product of isocyanates and polyols, the molecular weight of the isocyanate is 3000-6000, and the molecular weight of the polyol is 2000-4000.

[0025] Preferably, the particle dispersion during the warm mixing process in S6 reaches more than 90%, ensuring good bonding and uniformity between the regeneration agent and the asphalt, and avoiding stratification or sedimentation.

[0026] Preferably, the high-temperature heating process in S2 includes a first stage and a second stage: the first stage is a preheating stage at 60-80°C for activating polyvinyl alcohol and surfactants, and the second stage is a reaction stage at 110-130°C for ensuring that all ingredients in the regeneration agent formula fully react and enhance their performance.

[0027] The present invention provides an environmentally friendly warm mix asphalt regeneration agent and a preparation method thereof. It has the following beneficial effects:

[0028] This environmentally friendly warm-mix asphalt regeneration agent and its preparation method significantly improve the interfacial compatibility and dispersibility between the regeneration agent and aged asphalt, avoiding sedimentation and stratification; the introduction of nano-graphene / carbon nanotube composite materials and nano-silicon-sulfide composite additives not only enhances the structural strength and anti-aging ability of the regeneration agent, but also inhibits crack propagation at the micro level; the butylated hydroxyanisole antioxidant and the green polylactic acid component jointly play an anti-aging and environmental protection role, achieving an organic combination of high performance and low carbon emissions; the polyurethane self-healing component gives the regeneration agent the ability to automatically close microcracks during warm mixing or service, ensuring long-term stable performance.

[0029] The preparation process adopts a three-stage heating process of "60-80℃ preheating activation → 110-130℃ main reaction → solvent evaporation → particle size control" with a temperature accuracy of ±2℃ to ensure that all components fully react and the solvent is completely removed. The resulting solid powder has a water content of ≤1%, a particle size of 10-50μm, and a dispersion of >90%; the subsequent warm mixing process (1:10-1:20 mixing at 120-140℃) is simple and energy-saving, and can quickly and evenly integrate the regeneration agent into the asphalt system; the overall production process is easy to operate and can be promoted on a large scale industrially, significantly improving the thermal stability, crack resistance and service life of road materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flowchart for implementing the invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] like Figure 1 As shown, an embodiment of the present invention provides an environmentally friendly warm mix asphalt regeneration agent, including: a high molecular polymer: 20-30%, which is polyvinyl alcohol, the molecular weight of the high molecular polymer polyvinyl alcohol is 5000-10000, and the molecular weight of the surfactant polyoxyethylene ether is 1500-3000.

[0033] Surfactant: 5-10%, which is polyoxyethylene ether.

[0034] Nanocomposite material: 1-5%, which is a graphene / carbon nanotube composite material, with a mass ratio of graphene to carbon nanotubes of 2:1.

[0035] Antioxidant: 0.5-3%, butylated hydroxyanisole.

[0036] Multifunctional modification additive: 5-15%, which is a composite of nano silicon powder and sulfide, with nano silicon powder accounting for 80% and sulfide accounting for 20%.

[0037] Green and environmentally friendly ingredients: 0-5%, polylactic acid.

[0038] Solvent: 0-5%, which is a terpene solvent. The options of terpene solvents include lemon oil, orange peel oil or peppermint oil, which can help adjust the fluidity of the regeneration agent and ensure its uniform dispersion in the asphalt.

[0039] A method for preparing an environmentally friendly warm mix asphalt regeneration agent comprises the following steps:

[0040] S1. Poly(vinyl alcohol) polymer, surfactant polyoxyethylene ether, nanocomposite graphene / carbon nanotube composite, antioxidant butylated hydroxyanisole, multifunctional modifying additive nanosilicon powder and sulfide complex, environmentally friendly ingredient polylactic acid, and solvent terpene are mixed uniformly in appropriate mass ratios to form a homogeneous raw material mixture. The surfactant polyoxyethylene ether has a molecular weight of 2000-2500 and a surface tension of less than 40 mN / m, effectively promoting uniform dispersion of the regeneration agent and aged asphalt, preventing sedimentation or stratification.

[0041] S2. Heat the raw material mixture to a temperature between 110°C and 130°C and continue stirring at this temperature for 3-4 hours to ensure that all components fully react and form a uniform regeneration agent formula. The temperature is controlled with an accuracy of ±2°C. The high-temperature heating process in S2 consists of a first stage and a second stage: the first stage is a preheating stage at 60-80°C for activating the polyvinyl alcohol and surfactant, and the second stage is a reaction stage at 110-130°C for ensuring that all components in the regeneration agent formula fully react and enhance its performance.

[0042] The specific implementation is as follows:

[0043] In a 250 ml double-layer glass reactor, 50 g of the prepared raw material mixture was added, nitrogen was introduced to replace oxygen, a mechanical stirring paddle (400 rpm) and a thermocouple temperature sensor (accuracy ±0.1°C) were installed, and a reflux condenser was connected to the top to recover volatiles.

[0044] The first stage (60-80℃ preheating activation, a total of 30 minutes).

[0045] The temperature was raised from room temperature (25°C) to 75°C at a rate of about 2°C / min, which took about 25 minutes.

[0046] Then slowly raise the temperature to 80°C at 1.5°C / min, which takes about 7 minutes.

[0047] The mixture was stirred at 80°C for 30 minutes.

[0048] After sampling, the viscosity was measured by a Brookfield viscometer and was found to be approximately 28.4 Pa·s (100 rpm), which was much higher than 15 Pa·s at room temperature, indicating that the polyvinyl alcohol and polyoxyethylene ether had been fully wetted and activated.

[0049] In Fourier transform infrared spectroscopy (FT-IR), the stretching vibration peak of hydroxyl (–OH) (≈3400 cm -1 ) The absorbance increased by about 12%, further demonstrating the activation effect.

[0050] The initial dispersion of the nanocomposite material was observed under an optical microscope and was about 65%.

[0051] The second stage (main reaction at 110-130°C, 3.5 hours in total).

[0052] The temperature was raised to 110°C at 2°C / min, and then to 125°C at 1°C / min. The total heating time was about 27 minutes, and the temperature was controlled at 125±1.5°C.

[0053] The reaction was carried out at a constant temperature of 125°C for 3.5 hours, and samples were taken every hour. The results were as follows:

[0054] 0h: viscosity 128 mPa·s, water content 1.10 wt% (Karl Fischer volumetric titration method), dispersity 72%.

[0055] 1h: Viscosity 112 mPa·s, water content 1.00 wt%, dispersion 78%.

[0056] 2h: viscosity 102 mPa·s, water content 0.95 wt%, dispersion 85%.

[0057] 3.5h: viscosity 94mPa·s, water content 0.88wt%, dispersion 92%.

[0058] The sample taken at the end of 3.5 hours was observed by transmission electron microscopy (TEM), which showed that the graphene layers and carbon nanotubes were intertwined and distributed, and the average diameter of the composite agglomerates was ≈220nm.

[0059] The zeta potential measurement result was approximately –32 mV, indicating that the dispersed system had good charge stability;

[0060] Fourier transform infrared spectroscopy showed that the ether bond (≈1100 cm -1 ) The absorption peak intensity increased by about 10%, indicating that the cross-linking between components was enhanced.

[0061] After the reaction, the system was uniformly dark reddish brown, without stratification or precipitation, and the viscosity was stable at 95±4 mPa·s, meeting the requirements for subsequent solvent evaporation.

[0062] Environmental and safety monitoring:

[0063] The reaction was carried out at normal pressure (≈1.02 atm) throughout the process, and no overpressure occurred.

[0064] The energy consumption of this batch is about 1.8kWh.

[0065] The solvent recovery rate of reflux condensation is ≈96%, and the volatile organic compound (VOC) content in the tail gas is tested to be qualified.

[0066] Through the above-mentioned two-stage precise temperature control and multi-point online monitoring, the comprehensive completion of polymer activation, nanomaterial dispersion, component cross-linking and dehydration is ensured, providing high-quality intermediate products for subsequent S3–S7 steps.

[0067] S3. Continue heating and maintaining the temperature until the solvent is completely evaporated to obtain a solid regeneration agent formula, wherein the water content of the solid regeneration agent formula does not exceed 1%.

[0068] S4. The obtained solid regeneration agent formulation is cooled to room temperature and the particle size is adjusted to 10-50 μm by grinding or sieving.

[0069] S5. Continue stirring the cooled regeneration agent and add an appropriate amount of polyurethane material. This can enhance the regeneration agent's self-repairing function, allowing it to automatically repair microcracks during heating or use, improving its long-term stability. The polyurethane material is added in an amount of 1-3%. The polyurethane material is a polyurethane prepolymer, which is the reaction product of an isocyanate and a polyol. The molecular weight of the isocyanate is 3000-6000, and the molecular weight of the polyol is 2000-4000.

[0070] The specific implementation is as follows:

[0071] Preparation and weighing:

[0072] 50 g of regeneration agent powder obtained by S4 with a particle size distribution of 10–50 μm (average of about 20 μm) was placed in a 500 mL stainless steel stirring tank.

[0073] Adding polyurethane prepolymer:

[0074] Accurately weigh 1g of polyurethane prepolymer (2wt%), which is isocyanate-terminated (M n ≈4500) and polyether polyol (M n ≈3000) reaction product.

[0075] Dispersion and reaction conditions:

[0076] Heat the tank to 60°C and stir at 300 r / min for 1 hour; the heating and cooling rates are controlled within 2°C / min to keep the system uniform and avoid agglomeration.

[0077] Self-repair performance test:

[0078] Microcrack preparation: A small amount of the mixture was pressed into a cylindrical specimen with a diameter of 10 mm and a height of 5 mm, and microcracks with a depth of about 20 μm were artificially scratched on the side wall using a microknife.

[0079] Self-repair treatment: Place the specimen in a 120°C oven for 30 minutes.

[0080] Microscopic imaging: An optical microscope was used to capture images of the crack before and after the crack was formed. The crack width was measured to have shrunk from the original 20 μm to an average of 3 μm, with a closure rate of 85%.

[0081] Mixture appearance and stability:

[0082] After S5, the powder color changed from dark brown to uniform reddish brown, and the Zeta potential was measured to be –30 mV, indicating good charge stability. After being placed in a 50°C environmental chamber for 7 days, no visible agglomeration or stratification was observed.

[0083] S6. Mix the resulting regeneration agent with asphalt in a mass ratio of 1:10 to 1:20 and perform a warm mix operation at 120°C to 140°C to ensure uniform dispersion and complete integration of the regeneration agent into the asphalt. The particle dispersion during the warm mix should exceed 90%, ensuring good bonding and uniformity between the regeneration agent and the asphalt, and avoiding stratification or sedimentation.

[0084] The specific implementation is as follows:

[0085] Proportioning and heating:

[0086] 50 g of the regeneration agent of S5 and 750 g of aged asphalt sampled at room temperature (needle penetration 20 dmm) were put into the second reactor at a mass ratio of 1:15, and heated to 130°C at a heating rate of about 3°C / min.

[0087] Warm mix:

[0088] Stir at 250 r / min at 130°C for 30 minutes to ensure that the regeneration agent particles are fully dispersed and evenly integrated with the asphalt matrix; maintain reflux condensation to recover any volatile components.

[0089] Dispersion and rheological properties:

[0090] Dispersion test: A thin slice of warm-mix asphalt was taken and the particle dispersion was evaluated using a polarizing microscope and image analysis software. The result was 92%.

[0091] Brookfield viscosity (135℃, 200s -1 ):160mPa·s.

[0092] Needle penetration (25℃, 100g, 5s): 67dmm.

[0093] Softening point (R&B method): 54°C.

[0094] Heat aging stability:

[0095] The viscosity of the warm-mix modified asphalt was measured after RTFO (short-term aging). It was found that the viscosity change rate before and after aging was only 10%, which was better than the 18% increase in the control example (no polyurethane added).

[0096] Appearance and storage:

[0097] After the warm mixing is completed, the asphalt has a uniform color and no stratification or precipitation; after being stored in a sealed container at room temperature (25°C) for 30 days, the viscosity and needle penetration changes are both within 5%, indicating good long-term stability.

[0098] S7. Cooling the final mixed asphalt rejuvenator to room temperature to obtain a warm mix asphalt rejuvenator with good thermal stability, aging resistance, crack resistance and environmental friendliness, which is used for road construction and maintenance.

[0099] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly warm mix asphalt regeneration agent, characterized in that: include: High molecular weight polymer: 20-30%, polyvinyl alcohol; Surfactant: 5-10%, which is polyoxyethylene ether; Nanocomposite material: 1-5%, graphene / carbon nanotube composite material, wherein the mass ratio of graphene to carbon nanotube is 2:1; Antioxidant: 0.5-3%, butylated hydroxyanisole; Multifunctional modification additive: 5-15%, which is a composite of nano-silicon powder and sulfide, wherein the nano-silicon powder accounts for 80% and the sulfide accounts for 20%; Green and environmentally friendly ingredients: 0-5%, polylactic acid; Solvent: 0-5%, terpene solvent.

2. The environmentally friendly warm mix asphalt regeneration agent according to claim 1, characterized in that: The terpene solvent may be selected from lemon oil, orange peel oil or peppermint oil.

3. The environmentally friendly warm mix asphalt regeneration agent according to claim 1, characterized in that: The molecular weight of the high molecular weight polymer polyvinyl alcohol is 5000-10000, and the molecular weight of the surfactant polyoxyethylene ether is 1500-3000.

4. A method for preparing an environmentally friendly warm mix asphalt regeneration agent, characterized in that: include: S1. The polymer polyvinyl alcohol, the surfactant polyoxyethylene ether, the nanocomposite graphene / carbon nanotube composite material, the antioxidant butylated hydroxyanisole, the multifunctional modifying additive nanosilicon powder and sulfide complex, the green and environmentally friendly ingredient polylactic acid, and the solvent terpene solvent are mixed uniformly in a mass ratio to form a uniform raw material mixture; S2. The raw material mixture is heated to 110 to 130°C and stirred at this temperature for 3 to 4 hours with a temperature control accuracy of ±2°C; S3 continues heating and maintaining the temperature until the solvent is completely evaporated to obtain a solid regeneration agent formulation, wherein the water content of the solid regeneration agent formulation does not exceed 1%; S4. The resulting solid regeneration agent formulation is cooled to room temperature and the particle size is adjusted to 10-50 μm by grinding or sieving; S5. Continue stirring the cooled regeneration agent and add the polyurethane material; S6. The resulting regeneration agent is mixed with asphalt in a mass ratio of 1:10 to 1:20 and warm-mixed at 120 to 140 ° C; S7. Cool the final mixed asphalt rejuvenator to room temperature for use in road construction and maintenance.

5. The method for preparing an environmentally friendly warm mix asphalt regeneration agent according to claim 1, characterized in that: The molecular weight of the surfactant polyoxyethylene ether is 2000-2500 and the surface tension is lower than 40mN / m.

6. The method for preparing an environmentally friendly warm mix asphalt regeneration agent according to claim 1, characterized in that: The addition amount of the polyurethane material in S5 is 1-3%. The polyurethane material is a polyurethane prepolymer, which is a reaction product of isocyanates and polyols. The molecular weight of the isocyanate is 3000-6000, and the molecular weight of the polyol is 2000-4000.

7. The method for preparing an environmentally friendly warm mix asphalt regeneration agent according to claim 1, characterized in that: The particle dispersion during the warm mixing process in S6 reaches more than 90%.

8. The method for preparing an environmentally friendly warm mix asphalt regeneration agent according to claim 1, characterized in that: The high-temperature heating process in S2 includes a first stage and a second stage: the first stage is a preheating stage at 60-80°C, and the second stage is a reaction stage at 110-130°C.

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