Asphalt mixture additive as well as preparation method and application thereof

Abstract

The invention discloses an asphalt mixture additive as well as a preparation method and application thereof. The asphalt mixture additive comprises the following components in parts by weight: 100 parts of base asphalt; 1-10 parts of a modifier; 1-10 parts of a performance regulator; the performance regulator is obtained by modifying nano silicon dioxide with an accelerant, and the accelerant is a phosphate ester substance. The asphalt mixture additive disclosed by the invention is used in the asphalt mixture mixing process, and the use performances of high temperature resistance, stripping resistance, rutting resistance and the like of the asphalt mixture can be improved.

Description

Technical Field

[0001] This invention belongs to the field of asphalt, and specifically relates to an asphalt mixture additive, its preparation method, and its application. Background Technology

[0002] Asphalt, due to its good adhesion, ductility, and deformability, is widely used in road paving, roof waterproofing, and pipeline corrosion protection. However, because asphalt is a thermoplastic material, it undergoes irreversible plastic deformation when exposed to high temperatures, limiting its applications. For example, during road paving, high ground temperatures in summer can cause ruts and other problems. These issues severely affect the road performance of asphalt.

[0003] Especially during road paving, poor high-temperature resistance of asphalt will directly affect the service life of the road. Furthermore, long-term erosion and washing by rainwater can weaken the adhesion between asphalt and aggregate, leading to asphalt-aggregate separation and water damage, further impacting the service life of the asphalt pavement. To obtain high-performance road asphalt, various polymers, anti-rutting agents, antioxidants, and anti-stripping agents are added to modify the asphalt.

[0004] CN101525492A discloses a layered silicate nano-asphalt modifier, and CN101817982A discloses a nano-organic montmorillonite and SBS modified asphalt. However, the organic montmorillonite modifiers prepared by these methods require high shear rates and long shear times to ensure that the montmorillonite is fully and uniformly dispersed in the asphalt. Moreover, when the amount of organic montmorillonite added increases, it is difficult to achieve uniform and stable dispersion in the asphalt, which also reduces the adhesion and stability of the asphalt.

[0005] Nanomaterials possess characteristics such as small size effect and surface effect, which can alter the microstructure of asphalt, thereby improving its macroscopic properties. For example, nano-sized SiO2, with its large surface energy and excellent stability, is one of the commonly used nanomaterials in asphalt modification. Adding nano-sized SiO2 to asphalt increases the rutting factor and decreases the rheological aging index, indicating improved rutting and aging resistance. However, nano-SiO2 is prone to agglomeration, forming large aggregates that hinder the realization of the nano-effect. Furthermore, the large number of -Si-OH groups on the surface of nano-SiO2 makes it hydrophilic and oleophobic, resulting in poor compatibility with asphalt and difficulty in uniform dispersion, thus weakening its improving effect on asphalt.

[0006] Currently, methods such as high-intensity, high-speed shear mixing have been used to improve the dispersibility of nanoparticles in asphalt, thereby enhancing the overall performance of asphalt. Compared to mechanical mixing, surface modification of nanoparticles can not only reduce agglomeration between nanoparticles but also enhance the interfacial interaction between them through physical adsorption or chemical grafting, thus improving the performance of modified asphalt. Due to the inertness of the asphalt surface, surface treatment of nanoscale materials is necessary to chemically modify the asphalt and improve the overall performance of asphalt and its mixtures. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an asphalt mixture additive, its preparation method, and its application. This asphalt mixture additive, used during the asphalt mixture mixing process, can improve the performance of asphalt mixtures, including high-temperature resistance, spalling resistance, and rutting resistance.

[0008] The first aspect of the present invention provides an asphalt mixture additive, comprising, by weight:

[0009] 100 parts of base asphalt;

[0010] 1-10 parts of modifier;

[0011] Performance regulator 1-10 parts;

[0012] The performance regulator is obtained by modifying nano-silica with an accelerator. The accelerator is a phosphate ester, preferably at least one of dodecyl phosphate MAP, potassium monoalkyl phosphate MAP-K, fatty alcohol ether phosphate MOA-3P, and fatty alcohol ether phosphate MOA-9P.

[0013] Further, the performance modifier, by weight, comprises:

[0014] 100 parts of accelerator;

[0015] 60-100 parts of nano-silica;

[0016] 1 to 10 parts of coupling agent.

[0017] Furthermore, the particle size of the nano-silica is 20nm to 100nm.

[0018] Further, the coupling agent is a titanate coupling agent, preferably a chelating titanate coupling agent, and is further selected from at least one of bis(dioctyloxypyrophosphate) ethylene titanate, di(triethanolamine) titanate diisopropyl, and di(triethylamine) titanate diisopropyl.

[0019] Further, the modifier is obtained by activating pitch-based graphene microsheets with an activator. The modifier, by weight, comprises:

[0020] 100 parts activator;

[0021] 20-100 parts of pitch-based graphene micro flakes.

[0022] Furthermore, the average diameter of the pitch-based graphene microsheets is 10–100 nm, and the thickness is 10–50 nm.

[0023] Further, the activator is polyethyleneimine, preferably branched polyethyleneimine; more preferably, the molecular weight of polyethyleneimine is 1000 to 100000.

[0024] Furthermore, the asphalt content of the base asphalt is 40wt% to 80wt%, and the softening point is 100℃ to 200℃.

[0025] Further, the base asphalt is preferably obtained by mixing ethylene tar heavy fraction oil and hydrocracking unconverted oil, followed by oxidation and then polycondensation. The ethylene tar heavy fraction oil is a heavy fraction obtained after vacuum distillation to remove light components, with a distillation range >350℃. The hydrocracking unconverted oil is derived from conventional wax oil hydrocracking processes, with a distillation range >400℃. The mass ratio of the ethylene tar heavy fraction oil to the hydrocracking unconverted oil is 3:7 to 7:3.

[0026] Furthermore, the particle size of the asphalt mixture additive is 10-100 mesh.

[0027] A second aspect of the present invention provides a method for preparing the above-mentioned asphalt mixture additive, comprising:

[0028] (a) Preparation of the modifier;

[0029] (b) Preparation of performance modifiers;

[0030] (c) The modifier obtained in step (a) and the performance regulator prepared in step (b) are added to the molten base asphalt and mixed. The mixture is stirred and then reacted. After the reaction is completed, the mixture is cooled and crushed to obtain an asphalt mixture additive.

[0031] Further, in step (a), the method for preparing the modifier includes:

[0032] i) Preparation of pitch-based graphene microsheets;

[0033] ii) The activator is mixed and reacted with pitch-based graphene microsheets to prepare a modifier.

[0034] Further, in step i), the preparation method of pitch-based graphene micro flakes includes: adding concentrated nitric acid to the raw material pitch powder, reacting under stirring, with a reaction temperature of 70-90℃, a reaction time of 2-8h, a stirring speed of 20-200rpm, and after the reaction is completed, cooling, filtration, and drying to obtain pitch-based graphene micro flakes.

[0035] Further, in step i), the raw material asphalt is solvent-degraded asphalt and / or natural asphalt; the softening point of the raw material asphalt is 100-200℃.

[0036] Further, in step i), the mass ratio of the raw material asphalt to concentrated nitric acid is 1:5 to 20. The mass concentration of the concentrated nitric acid is 65% to 70%.

[0037] Furthermore, in step i), the filtration and drying can be performed using conventional methods in the art. Before filtration, the solution can be diluted with a diluent, such as distilled water.

[0038] Further, in step ii), the activator is mixed and reacted with pitch-based graphene microsheets, specifically including:

[0039] 1) The pitch-based graphene microsheets prepared in step i) are mixed with epoxy silane coupling agent and ethanol, heated and refluxed, the resulting suspension is centrifuged, the precipitate is ultrasonically dispersed with ethanol, the supernatant is removed, washed and dried to obtain the intermediate product.

[0040] 2) Dissolve the activator in ethanol, add the intermediate product obtained in step 1), heat under reflux, centrifuge the resulting suspension, disperse the precipitate with water by ultrasonication, remove the supernatant, wash, and dry to obtain the modifier.

[0041] Further, in step 1), the epoxy silane coupling agent is 3-glycidyl etheroxypropylmethyldiethoxysilane (GPTMS). The mass-to-volume ratio of the pitch-based graphene microsheets to the epoxy silane coupling agent is 1:1 to 3 g / mL; the pitch-based graphene microsheets, epoxy silane coupling agent, and ethanol are mixed, wherein the volume ratio of the epoxy silane coupling agent to ethanol is 1:1 to 5.

[0042] Furthermore, in steps 1) and 2), the conditions for the heating reflux are each independent:

[0043] The temperature is 80–120℃, and the heating and reflux time is 12–36 h.

[0044] Further, in step 1), the centrifugation speed is 5000–15000 rpm, and the centrifugation time is 10–30 min. The ultrasonic dispersion frequency is 20 kHz–60 kHz, and the ultrasonic dispersion time is 5–20 min. The drying temperature is 50–80 °C, and the drying time is 5–20 h.

[0045] Furthermore, the ethanol used in steps 1) and 2) is anhydrous ethanol.

[0046] Further, in step 2), the amount of activator added is 1-20% based on the mass of ethanol. The amount of intermediate product added is 1-30% based on the mass of ethanol. The mass ratio of activator to intermediate product is 1:1-2.

[0047] Further, in step 2), the centrifugation speed is 5000–15000 rpm, and the centrifugation time is 10–30 min. The ultrasonic dispersion frequency is 20 kHz–60 kHz, and the ultrasonic dispersion time is 5–20 min. The drying temperature is 50–80 °C, and the drying time is 5–20 h.

[0048] Further, in step (b), the method for preparing the performance modifier includes:

[0049] Nano-silica was added to a reaction vessel, and water vapor and nitrogen were introduced simultaneously to carry out a primary reaction; then an accelerator and coupling agent were added to carry out a secondary reaction. After the reaction was completed, the material was cooled and dried to obtain the performance regulator.

[0050] Furthermore, the total amount of water vapor and nitrogen introduced satisfies the system pressure of 0.1 to 0.5 MPa, wherein the volume ratio of water vapor to nitrogen is 1 to 5:1.

[0051] Furthermore, the conditions for the first reaction are: a reaction temperature of 100–140°C and a reaction time of 10–30 min.

[0052] Furthermore, the pressure is reduced to atmospheric pressure before adding the accelerator and coupling agent.

[0053] Furthermore, the conditions for the secondary reaction are: reaction temperature 80–120°C, reaction time 10–60 min, and the reaction is carried out under stirring at a speed of 50–500 rpm.

[0054] Furthermore, the drying conditions are as follows: the drying temperature is 40–80°C, and the drying time is 1–20 hours.

[0055] Further, in step (c), the method for preparing the base asphalt includes: mixing ethylene tar heavy fraction oil with hydrocracking unconverted oil, followed by an oxidation-polymerization reaction. Specifically, the ethylene tar heavy fraction oil and hydrocracking unconverted oil are added to a reactor at a mass ratio of 3:7 to 7:3. The mixture is first heated to 250–300°C, air is introduced, the reaction pressure is 0.2–1.0 MPa, and the reaction time is 20–90 min. Then, the mixture is heated a second time at a temperature 50–100°C higher than the first heating temperature, inert gas is introduced, the reaction pressure is 1.0–2.0 MPa, and the reaction time is 60–180 min to obtain the base asphalt.

[0056] Further, in step (c), the reaction temperature is 150–250°C, and the reaction time is 1–10 h. The stirring speed is 50–500 rpm.

[0057] Further, in step (c), the cooling is cooling to -20°C to 0°C.

[0058] A third aspect of the present invention provides an application of the above-mentioned asphalt mixture additive in road construction.

[0059] Furthermore, the application specifically involves first mixing the asphalt mixture additive with road asphalt, and then mixing it with aggregate and mineral powder; alternatively, the road asphalt can be mixed with aggregate first, and then the aforementioned asphalt mixture additive and mineral powder can be added and mixed further to obtain an asphalt mixture for road construction.

[0060] Further, after mixing the aggregates according to the required proportions, heat the mixture to 160–190°C for dehumidification and maintain the temperature, then mix thoroughly. Add the aforementioned asphalt mixture additives to the road asphalt and mix for 30–60 seconds. Add the dehumidified and heat-maintained aggregates and mix for 30–90 seconds. Add mineral powder and continue mixing for 30–60 seconds to obtain the asphalt mixture. Alternatively, this mixing process can be performed by first adding road asphalt to the aggregates and mixing for 45–90 seconds, then adding the asphalt mixture additives and mixing for 30–90 seconds, and finally adding mineral powder and continuing mixing for 30–60 seconds.

[0061] Furthermore, the amount of asphalt mixture additives added accounts for 1 wt% to 20 wt% of the mass of road asphalt.

[0062] Compared with the prior art, the present invention has the following advantages:

[0063] (1) The asphalt mixture additive of the present invention firstly uses branched polyethyleneimine to activate asphalt-based graphene micro flakes. The base asphalt is asphalt with high asphalt content. Its asphalt can undergo a grafting reaction with the surface-activated asphalt-based graphene micro flakes, making it easier for cationic active groups to be evenly and firmly distributed on the asphalt surface. This can effectively increase the softening point of asphalt, which can not only improve the high temperature resistance and rutting resistance, but also make the additive evenly dispersed in the asphalt mixture in a shorter mixing time, thereby improving the overall performance of the mixture.

[0064] (2) In the process of preparing the performance regulator, the present invention first contacts the SiO2 surface with water vapor to activate and generate a large number of hydroxyl groups, which can graft specific phosphate esters onto the SiO2 surface, and can quickly and stably disperse the phosphate esters into the asphalt mixture, thereby improving the asphalt mixture's resistance to spalling and further improving the overall performance of the asphalt pavement. Detailed Implementation

[0065] The technical solution of the present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments. In the present invention, wt% is a mass fraction.

[0066] First, ethylene cracking tar was subjected to vacuum distillation to remove light components, yielding a heavy ethylene tar fraction with an initial boiling point >350℃, an asphaltenes content of 28.7%, and a softening point of 92.3℃. This heavy ethylene tar fraction was used as feedstock in the following examples and comparative examples. The unconverted hydrocracking oil was a fraction with an initial boiling point >400℃, an asphaltenes content of 11.5%, and a softening point of 30.6℃.

[0067] Example 1

[0068] (a) 48g of asphalt powder with a softening point of 153.8℃ was added to a flask, and 400g of concentrated nitric acid (65%) was slowly added. The reaction was carried out with stirring at a temperature of 90℃ for 6 hours and a stirring speed of 50 rpm. After the reaction was completed, the mixture was cooled to room temperature, diluted with a small amount of distilled water, and filtered through a microporous membrane. The filtrate was evaporated to dryness by vacuum distillation to obtain asphalt-based graphene microsheets (average sheet diameter 40nm, thickness 25nm).

[0069] Take 36g of the prepared pitch-based graphene microsheets, 46mL of 3-glycidyl etheroxypropylmethyldiethoxysilane, and 200mL of ethanol, add them to a flask, and stir and reflux the mixture at 100℃ for 22h. Then, centrifuge the suspension at 12000rpm for 20min and remove the supernatant; sonicate with 85mL of ethanol for 16min at a frequency of 20kHz, remove the supernatant, repeat the washing three times, and place the product in a 60℃ oven for 18h to obtain the intermediate product.

[0070] 55g of polyethyleneimine (molecular weight 2000) was dissolved in 350g of ethanol and stirred until homogeneous. Then, 60g of the intermediate product prepared above was added, and the mixture was stirred and refluxed at 105℃ for 16h. The suspension was then centrifuged at 11000rpm for 20min, and the supernatant was removed. The mixture was then ultrasonically dispersed with deionized water at a frequency of 20kHz for 10min, and the supernatant was removed. The washing was repeated three times, and the product was placed in a 70℃ oven for 10h to obtain the modifier.

[0071] (b) 21.5 g of nano-silica (particle size 20 nm) was added to a reactor, and water vapor and nitrogen gas were simultaneously introduced, with a volume ratio of water vapor to nitrogen gas of 3:1. The reactor pressure was maintained at 0.3 MPa, and the reaction was carried out at 120 °C for 15 min. Then, the reactor pressure was reduced to atmospheric pressure, and 30.8 g of potassium monoalkyl phosphate salt MAP-K and 2.5 g of diisopropyl di(triethanolamine)titanate were added. The reaction was carried out again under stirring at 100 °C for 50 min and a stirring speed of 200 rpm. After the reaction was completed, the material was cooled to room temperature. It was then dried in a 65 °C oven for 10 h to obtain the performance regulator.

[0072] (c) 120g of ethylene tar heavy fraction oil and 180g of hydrocracking unconverted oil were mixed and added to a reactor. The mixture was heated to 280°C, air was introduced, the reaction pressure was 0.6MPa, and the reaction time was 75min. Then the temperature was raised to 350°C, N2 was introduced, the reaction pressure was 1.4MPa, and the reaction time was 70min to obtain the base asphalt. The properties are shown in Table 1.

[0073] 200g of the prepared base asphalt was heated to a molten state, and 19.8g of the prepared modifier and 12.6g of the prepared performance regulator were added. The mixture was stirred and mixed at 195℃ for 2.5h at a stirring speed of 120rpm. After the reaction was completed, the mixture was cooled to -15℃, pulverized, and the asphalt mixture additive was obtained. Its properties are shown in Table 2.

[0074] Example 2

[0075] (a) 58g of asphalt powder with a softening point of 146.2℃ was added to a flask, and 320g of concentrated nitric acid (68%) was slowly added. The reaction was carried out with stirring at a temperature of 85℃ for 4.5h and a stirring speed of 100rpm. After the reaction was completed, the mixture was cooled to room temperature, diluted with a small amount of distilled water, and filtered through a microporous membrane. The filtrate was evaporated to dryness by vacuum distillation to obtain asphalt-based graphene microsheets (average sheet diameter 75nm, thickness 40nm).

[0076] Take 48g of the prepared pitch-based graphene microsheets, 60mL of 3-glycidyl etheroxypropylmethyldiethoxysilane, and 160mL of ethanol, add them to a flask, and stir and reflux the mixture at 105℃ for 28h. Then, centrifuge the suspension at 12500rpm for 20min and remove the supernatant; sonicate with 100mL of ethanol for 12min at a frequency of 20kHz, remove the supernatant, repeat the washing process 3 times, and place the product in a 70℃ oven for 10h to obtain the intermediate product.

[0077] 48g of polyethyleneimine (molecular weight 1000) was dissolved in 280g of ethanol and stirred until homogeneous. Then, 55g of the intermediate product prepared above was added, and the mixture was stirred and refluxed at 110℃ for 25h. The suspension was then centrifuged at 12000rpm for 25min, and the supernatant was removed. The mixture was then ultrasonically dispersed with deionized water for 18min at a frequency of 20kHz, and the supernatant was removed. The washing was repeated three times, and the product was placed in a 75℃ oven for 12h to obtain the modifier.

[0078] (b) 28.2 g of nano-silica (particle size 50 nm) was added to a reactor, and water vapor and nitrogen gas were simultaneously introduced, with a water vapor to nitrogen gas volume ratio of 2:1. The reactor pressure was maintained at 0.2 MPa, and the reaction was carried out at 130 °C for 25 min. Then the reactor pressure was reduced to atmospheric pressure. 42.5 g of dodecyl phosphate (MAP) and 1.8 g of di(triethylamine)titanate (DIT) were added, and the reaction was carried out again under stirring. The reaction temperature was 110 °C, the reaction time was 35 min, and the stirring speed was 350 rpm. After the reaction was completed, the material was cooled to room temperature. It was then dried in a 70 °C oven for 8 h to obtain the performance regulator.

[0079] (c) 100g of ethylene tar heavy fraction oil and 200g of hydrocracking unconverted oil were mixed and added to a reactor. The mixture was heated to 290°C, air was introduced, the reaction pressure was 0.5MPa, and the reaction time was 80min. Then the temperature was raised to 345°C, N2 was introduced, the reaction pressure was 1.6MPa, and the reaction time was 120min to obtain the base asphalt. The properties are shown in Table 1.

[0080] 200g of the prepared base asphalt was heated to a molten state, and 15.6g of the prepared modifier and 17.2g of the prepared performance regulator were added. The mixture was stirred and mixed at 185℃ for 3 hours at a stirring speed of 200 rpm. After the reaction was completed, the mixture was cooled to -18℃ and pulverized. The properties of the asphalt mixture additive are shown in Table 2.

[0081] Example 3

[0082] (a) 52g of asphalt powder with a softening point of 163.3℃ was added to a flask, and 430g of concentrated nitric acid (65%) was slowly added. The reaction was carried out with stirring at 70℃ for 7.5h and a stirring speed of 120rpm. After the reaction was completed, the mixture was cooled to room temperature, diluted with a small amount of distilled water, and filtered through a microporous membrane. The filtrate was evaporated to dryness by vacuum distillation to obtain asphalt-based graphene microsheets (average sheet diameter 80nm, thickness 35nm).

[0083] Take 43.8 g of the prepared pitch-based graphene microsheets, 85 mL of 3-glycidyl etheroxypropylmethyldiethoxysilane, and 260 mL of ethanol, add them to a flask, and stir and reflux the mixture at 115 °C for 20 h. Then, centrifuge the suspension at 13000 rpm for 25 min, remove the supernatant, and sonicate with 120 mL of ethanol for 20 min at a frequency of 40 kHz. Remove the supernatant, repeat the washing process three times, and place the product in a 70 °C oven for 20 h to obtain the intermediate product.

[0084] 56.5 g of polyethyleneimine (molecular weight 5000) was dissolved in 350 g of ethanol and stirred until homogeneous. Then, 61.4 g of the intermediate product prepared above was added, and the mixture was stirred and refluxed at 100 °C for 32 h. The suspension was then centrifuged at 12000 rpm for 25 min, and the supernatant was removed. The mixture was then ultrasonically dispersed with deionized water for 15 min at a frequency of 40 kHz. The supernatant was removed, and the mixture was washed three times. The product was then placed in a 70 °C oven for 18 h to obtain the modifier.

[0085] (b) 33.4 g of nano-silica (75 nm particle size) was added to a reactor, and water vapor and nitrogen gas were simultaneously introduced, with a water vapor to nitrogen gas volume ratio of 2.5:1. The reactor pressure was maintained at 0.25 MPa, and the reaction was carried out at 135 °C for 30 min. Then, the reactor pressure was reduced to atmospheric pressure. 38.2 g of fatty alcohol ether phosphate MOA-9P and 1.4 g of di(triethylamine)titanate diisopropyl ester were added, and the reaction was carried out again under stirring. The reaction temperature was 95 °C, the reaction time was 45 min, and the stirring speed was 300 rpm. After the reaction was completed, the material was cooled to room temperature. It was then dried in a 55 °C oven for 16 h to obtain the performance regulator.

[0086] (c) 150g of ethylene tar heavy fraction oil and 150g of hydrocracking unconverted oil were mixed and added to a reactor. The mixture was heated to 280°C, air was introduced, the reaction pressure was 0.7MPa, and the reaction time was 75min. Then the temperature was raised to 360°C, N2 was introduced, the reaction pressure was 1.2MPa, and the reaction time was 150min to obtain the base asphalt. The properties are shown in Table 1.

[0087] 200g of the prepared base asphalt was heated to a molten state, and 14.5g of the prepared modifier and 11.8g of the prepared performance regulator were added. The mixture was stirred and mixed at 200℃ for 1.5h at a stirring speed of 150rpm. After the reaction was completed, the mixture was cooled to -10℃, pulverized, and the asphalt mixture additive was obtained. Its properties are shown in Table 2.

[0088] Example 4

[0089] (a) 50g of asphalt powder with a softening point of 158.4℃ was added to a flask, and 400g of concentrated nitric acid (65wt%) was slowly added. The reaction was carried out with stirring at 85℃ for 3 hours and a stirring speed of 150rpm. After the reaction was completed, the mixture was cooled to room temperature, diluted with a small amount of distilled water, and filtered through a microporous membrane. The filtrate was evaporated to dryness by vacuum distillation to obtain asphalt-based graphene microsheets (average sheet diameter 50nm, thickness 35nm).

[0090] Take 31.6 g of the prepared pitch-based graphene microsheets, 65 mL of 3-glycidyl etheroxypropylmethyldiethoxysilane, and 250 mL of ethanol, add them to a flask, and stir and reflux the mixture at 115 °C for 25 h. Then, centrifuge the suspension at 13000 rpm for 20 min and remove the supernatant; sonicate with 130 mL of ethanol for 18 min at a frequency of 40 kHz, remove the supernatant, repeat the washing process 3 times, and place the product in a 75 °C oven for 6 h to obtain the intermediate product.

[0091] 38.4 g of polyethyleneimine (molecular weight 7000) was dissolved in 200 g of ethanol and stirred until homogeneous. Then, 45.6 g of the intermediate product prepared above was added, and the mixture was stirred and refluxed at 120 °C for 30 h. The suspension was then centrifuged at 13500 rpm for 20 min, and the supernatant was removed. The mixture was then ultrasonically dispersed with deionized water for 18 min at a frequency of 40 kHz. The supernatant was removed, and the mixture was washed three times. The product was then placed in a 70 °C oven for 9 h to obtain the modifier.

[0092] (b) 41.5 g of nano-silica (particle size 35 nm) was added to a reactor, and water vapor and nitrogen gas were simultaneously introduced, with a volume ratio of water vapor to nitrogen gas of 4:1. The reactor pressure was maintained at 0.45 MPa, and the reaction was carried out at 140 °C for 20 min. Then, the reactor pressure was reduced to atmospheric pressure. 50.6 g of fatty alcohol ether phosphate MOA-3P and 2.8 g of di(triethylamine)titanate diisopropyl ester were added, and the reaction was carried out again under stirring. The reaction temperature was 115 °C, the reaction time was 55 min, and the stirring speed was 250 rpm. After the reaction was completed, the material was cooled to room temperature. It was then dried in a 60 °C oven for 12 h to obtain the performance regulator.

[0093] (c) 170g of ethylene tar heavy fraction oil and 130g of hydrocracking unconverted oil were mixed and added to a reactor. The mixture was heated to 295°C, air was introduced, the reaction pressure was 0.9 MPa, and the reaction time was 80 min. Then the temperature was raised to 350°C, N2 was introduced, the reaction pressure was 1.5 MPa, and the reaction time was 160 min to obtain the basic asphalt. The properties are shown in Table 1.

[0094] 200g of the prepared base asphalt was heated to a molten state, and 14.2g of the prepared modifier and 12.4g of the prepared performance regulator were added. The mixture was stirred and mixed at 180°C for 2.5 hours at a stirring speed of 300 rpm. After the reaction was completed, the mixture was cooled to -20°C and pulverized to obtain the asphalt mixture additive, the properties of which are shown in Table 2.

[0095] Comparative Example 1

[0096] (a) 50g of asphalt powder with a softening point of 158.4℃ was added to a flask, and 400g of concentrated nitric acid (65wt%) was slowly added. The reaction was carried out with stirring at 85℃ for 3 hours and a stirring speed of 150rpm. After the reaction was completed, the mixture was cooled to room temperature, diluted with a small amount of distilled water, and filtered through a microporous membrane. The filtrate was evaporated to dryness by vacuum distillation to obtain asphalt-based graphene microsheets (average sheet diameter 50nm, thickness 35nm).

[0097] (b) 170g of ethylene tar heavy fraction oil and 130g of hydrocracking unconverted oil were mixed and added to a reactor. The mixture was heated to 295°C, air was introduced, the reaction pressure was 0.9 MPa, and the reaction time was 80 min. Then the temperature was raised to 350°C, N2 was introduced, the reaction pressure was 1.5 MPa, and the reaction time was 160 min to obtain the base asphalt. The properties are shown in Table 1.

[0098] 200g of the prepared base asphalt was heated to a molten state, and 14.2g of the prepared graphene microsheets were added. The mixture was stirred at 180°C for 2.5 hours at a stirring speed of 300 rpm. After the reaction was completed, the mixture was cooled to -20°C and pulverized to obtain the asphalt mixture additive, the properties of which are shown in Table 2.

[0099] Comparative Example 2

[0100] (a) 50g of asphalt powder with a softening point of 158.4℃ was added to a flask, and 400g of concentrated nitric acid (65wt%) was slowly added. The reaction was carried out with stirring at 85℃ for 3 hours and a stirring speed of 150rpm. After the reaction was completed, the mixture was cooled to room temperature, diluted with a small amount of distilled water, and filtered through a microporous membrane. The filtrate was evaporated to dryness by vacuum distillation to obtain asphalt-based graphene microsheets (average sheet diameter 50nm, thickness 35nm).

[0101] Take 31.6 g of the prepared pitch-based graphene microsheets, 65 mL of 3-glycidyl etheroxypropylmethyldiethoxysilane, and 250 mL of ethanol, add them to a flask, and stir and reflux the mixture at 115 °C for 25 h. Then, centrifuge the suspension at 13000 rpm for 20 min and remove the supernatant; sonicate with 130 mL of ethanol for 18 min at a frequency of 40 kHz, remove the supernatant, repeat the washing process 3 times, and place the product in a 75 °C oven for 6 h to obtain the intermediate product.

[0102] 38.4 g of polyethyleneimine (molecular weight 7000) was dissolved in 200 g of ethanol and stirred until homogeneous. Then, 45.6 g of the intermediate product prepared above was added, and the mixture was stirred and refluxed at 120 °C for 30 h. The suspension was then centrifuged at 13500 rpm for 20 min, and the supernatant was removed. The mixture was then ultrasonically dispersed with deionized water for 18 min at a frequency of 40 kHz. The supernatant was removed, and the mixture was washed three times. The product was then placed in a 70 °C oven for 9 h to obtain the modifier.

[0103] (b) Add 41.5g of nano-silica (particle size of 35nm) to the reactor, add 50.6g of fatty alcohol ether phosphate MOA-3P and 2.8g of di(triethylamine)titanate diisopropyl ester, stir at room temperature for 55min at a stirring speed of 250rpm to obtain the performance regulator.

[0104] (c) 170g of ethylene tar heavy fraction oil and 130g of hydrocracking unconverted oil were mixed and added to a reactor. The mixture was heated to 295°C, air was introduced, the reaction pressure was 0.9 MPa, and the reaction time was 80 min. Then the temperature was raised to 350°C, N2 was introduced, the reaction pressure was 1.5 MPa, and the reaction time was 160 min to obtain the basic asphalt. The properties are shown in Table 1.

[0105] 200g of the prepared base asphalt was heated to a molten state, and 14.2g of the prepared modifier and 12.4g of the prepared performance regulator were added. The mixture was stirred and mixed at 180°C for 2.5 hours at a stirring speed of 300 rpm. After the reaction was completed, the mixture was cooled to -20°C and pulverized to obtain the asphalt mixture additive, the properties of which are shown in Table 2.

[0106] Test case

[0107] The asphalt mixture additives from Examples 1-4 and Comparative Examples 1-2 were used to prepare asphalt mixtures. The preparation process is as follows: After batching according to the AC-13 grade aggregate ratio requirements, the mixture was heated to 180℃ for dehumidification and kept at that temperature, and then mixed evenly for later use; the asphalt mixture additives were added to the road asphalt and mixed for 35 seconds, followed by the addition of the dehumidified aggregate and mixing for 40 seconds; mineral powder was added and mixing was continued for 40 seconds to obtain the asphalt mixture, the properties of which are shown in Table 3.

[0108] The road asphalt used was 70A asphalt produced by Sinopec, accounting for 4.6% of the total weight of the asphalt mixture; the asphalt mixture additives accounted for 10% of the road asphalt content, and the mixing temperature was 165℃. The mixed asphalt mixture was kept warm in an oven at 170℃, and then molded into Marshall specimens at 165℃ for relevant performance tests.

[0109] The freeze-thaw splitting test involves vacuum saturating the standard specimen with water for 15 minutes according to the T0717 standard water saturation test method, followed by immersion in water for 0.5 hours under normal pressure; freezing it in a constant temperature refrigerator (-18℃) for 16 hours, then keeping it warm in a constant temperature water bath at 60℃ for 24 hours; finally immersing the specimen in a constant temperature water bath at 25℃ for at least 2 hours; and then performing a splitting test on the specimen with a loading rate of 50 mm / min. The data are shown in Table 3.

[0110] Table 1 Properties of Basic Asphalt

[0111] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Softening point, ℃ 138.6 140.2 146.6 155.5 155.5 155.5 Asphalt, % 45.6 50.4 48.2 52.3 52.3 52.3

[0112] Table 2 Properties of Asphalt Mixture Additives

[0113] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Softening point, ℃ 145.8 148.6 155.4 168.3 155.9 159.4 Zeta potential / mV +25.2 +26.6 +28.8 +32.6 - +24.0 Particle size, mesh 40 60 40 60 60 60 Dispersion good good good good Difference good

[0114] Table 3. Performance of asphalt mixtures in Examples 1-4 and Comparative Examples 1-2

[0115]

[0116] The scope of protection of this invention is not limited to the above embodiments, but is defined by the claims. Those skilled in the art can make appropriate modifications to these embodiments without departing from the technical concept and spirit of this invention, and these modified embodiments are also included within the scope of protection of this invention.

Claims

1. An asphalt mixture additive, characterized in that, The asphalt mixture additive, by weight, comprises: 100 parts of base asphalt; 1-10 parts of modifier; Performance regulator 1-10 parts; The performance regulator is obtained by modifying nano-silica with an accelerator. The accelerator is a phosphate ester, preferably at least one of dodecyl phosphate MAP, potassium monoalkyl phosphate MAP-K, fatty alcohol ether phosphate MOA-3P, and fatty alcohol ether phosphate MOA-9P.

2. The asphalt mixture additive according to claim 1, characterized in that, The performance modifier, by weight, comprises: 100 parts of accelerator; 60-100 parts of nano-silica; 1 to 10 parts of coupling agent.

3. The asphalt mixture additive according to claim 2, characterized in that, The particle size of the nano-silica is 20nm to 100nm.

4. The asphalt mixture additive according to claim 2, characterized in that, The coupling agent is a titanate coupling agent, preferably a chelating titanate coupling agent, and further selected from at least one of bis(dioctyloxypyrophosphate) ethylene titanate, di(triethanolamine) titanate diisopropyl, and di(triethylamine) titanate diisopropyl.

5. The asphalt mixture additive according to claim 1, characterized in that, The modifier is obtained by activating asphalt-based graphene microsheets with an activator, and the modifier comprises, by weight parts: 100 parts activator; 20-100 parts of pitch-based graphene micro flakes.

6. The asphalt mixture additive according to claim 5, characterized in that, The average diameter of the pitch-based graphene microsheets is 10–100 nm, and the thickness is 10–50 nm. And / or, the activator is polyethyleneimine, preferably branched polyethyleneimine; more preferably, the molecular weight of polyethyleneimine is 1,000 to 100,000.

7. The asphalt mixture additive according to claim 1, characterized in that, The asphalt content of the base asphalt is 40wt% to 80wt%, and the softening point is 100℃ to 200℃.

8. The asphalt mixture additive according to claim 1, characterized in that, The particle size of the asphalt mixture additive is 10-100 mesh.

9. A method for preparing asphalt mixture additives according to any one of claims 1-8, comprising: (a) Preparation of the modifier; (b) Preparation of performance modifiers; (c) The modifier obtained in step (a) and the performance regulator prepared in step (b) are added to the molten base asphalt and mixed. The mixture is stirred and then reacted. After the reaction is completed, the mixture is cooled and crushed to obtain an asphalt mixture additive.

10. The preparation method according to claim 9, characterized in that, In step (a), the method for preparing the modifier includes: i) Preparation of pitch-based graphene microsheets; ii) The activator is mixed and reacted with pitch-based graphene microsheets to prepare a modifier.

11. The preparation method according to claim 10, characterized in that, In step i), the preparation method of pitch-based graphene micro flakes includes: adding concentrated nitric acid to the raw material pitch powder, reacting under stirring, with a reaction temperature of 70-90℃, a reaction time of 2-8h, and a stirring speed of 20-200rpm; after the reaction is completed, cooling, filtration, and drying are performed to obtain pitch-based graphene micro flakes.

12. The preparation method according to claim 10, characterized in that, In step ii), the activator is mixed and reacted with pitch-based graphene microsheets, specifically including: 1) The pitch-based graphene microsheets prepared in step i) are mixed with epoxy silane coupling agent and ethanol, heated and refluxed, the resulting suspension is centrifuged, the precipitate is ultrasonically dispersed with ethanol, the supernatant is removed, washed and dried to obtain the intermediate product. 2) Dissolve the activator in ethanol, add the intermediate product obtained in step 1), heat under reflux, centrifuge the resulting suspension, disperse the precipitate with water by ultrasonication, remove the supernatant, wash, and dry to obtain the modifier.

13. The preparation method according to claim 12, characterized in that, In step 1), the epoxy silane coupling agent is 3-glycidyl etheroxypropylmethyldiethoxysilane; And / or, the mass-to-volume ratio of the pitch-based graphene microsheets to the epoxy silane coupling agent is 1:1 to 3 g / mL; And / or, mix pitch-based graphene microsheets, epoxy silane coupling agent and ethanol, wherein the volume ratio of epoxy silane coupling agent to ethanol is 1:1 to 5.

14. The preparation method according to claim 12, characterized in that, In steps 1) and 2), the heating and reflux conditions are each independent: the temperature is 80-120°C and the heating and reflux time is 12-36h.

15. The preparation method according to claim 12, characterized in that, In step 2), the amount of activator added is 1-20% based on the mass of ethanol; the amount of intermediate product added is 1-30% based on the mass of ethanol; wherein the mass ratio of activator to intermediate product added is 1:1-2.

16. The preparation method according to claim 9, characterized in that, In step (b), the method for preparing the performance modifier includes: Nano-silica was added to a reaction vessel, and water vapor and nitrogen were introduced simultaneously to carry out a primary reaction; then an accelerator and coupling agent were added to carry out a secondary reaction. After the reaction was completed, the material was cooled and dried to obtain the performance regulator.

17. The preparation method according to claim 16, characterized in that, The total amount of water vapor and nitrogen introduced satisfies the system pressure of 0.1 to 0.5 MPa, wherein the volume ratio of water vapor to nitrogen is 1 to 5:1; And / or, the conditions for the first reaction are: a reaction temperature of 100–140°C and a reaction time of 10–30 min; And / or, the conditions for the secondary reaction are: reaction temperature 80-120℃, reaction time 10-60 min, the reaction is carried out under stirring, and the stirring speed is 50-500 rpm.

18. The preparation method according to claim 9, characterized in that, In step (c), the preparation method of the base asphalt includes: mixing ethylene tar heavy fraction oil with hydrocracking unconverted oil, and then carrying out an oxidation followed by polycondensation reaction; specifically, adding ethylene tar heavy fraction oil and hydrocracking unconverted oil to a reaction vessel at a mass ratio of 3:7 to 7:3, heating for the first time, introducing air, with a reaction pressure of 0.2 to 1.0 MPa and a reaction time of 20 to 90 min; then heating for the second time, introducing inert gas, with a reaction pressure of 1.0 to 2.0 MPa and a reaction time of 60 to 180 min, to obtain the base asphalt.

19. The preparation method according to claim 9, characterized in that, In step (c), the reaction temperature is 150–250°C, the reaction time is 1–10 h, and the stirring speed is 50–500 rpm.

20. The application of the asphalt mixture additive according to any one of claims 1-8 or the asphalt mixture additive prepared by any one of claims 9-19 in road construction.

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