Rubber powder grafted nano material composite modifier modified asphalt, preparation method thereof and asphalt mixture

Abstract

The invention discloses rubber powder grafted nano material composite modifier modified asphalt, a preparation method thereof and an asphalt mixture, and belongs to the technical field of modified asphalt. The modified asphalt is prepared by modifying a carboxylated nano material grafted with aminated rubber powder. According to the invention, the rubber powder and the nano material are grafted, so that the advantages of the rubber powder and the nano material can be fully played, the high temperature, low temperature, water stability and other properties of asphalt and asphalt mixtures are remarkably improved, and a new solution is provided for high performance and sustainable development of asphalt pavements; therefore, the method has good application prospect and value in the field of road engineering.

Description

Technical Field

[0001] The invention belongs to the technical field of modified asphalt, and in particular relates to a rubber powder-grafted nano material composite modifier modified asphalt, a preparation method thereof and an asphalt mixture. Background Art

[0002] With the rapid development of transportation, asphalt pavement has become the main form of road construction due to its many advantages. However, traditional matrix asphalt and asphalt mixtures have exposed a series of performance defects during use, making it difficult to meet the growing needs of modern transportation. In summer, when the temperature is high, traditional asphalt mixtures are prone to rutting, congestion and other diseases. In some sections with large traffic volume and heavy vehicles, rutting diseases are particularly serious, which not only affects the flatness of the road surface and reduces driving comfort, but also shortens the service life of the road surface and increases maintenance costs. Asphalt pavements in cold areas often face the problem of low-temperature cracking. When the temperature drops, the flexibility of asphalt decreases, becoming hard and brittle. Under the combined action of temperature stress and vehicle load, cracks are easily generated. Once these cracks are formed, they will gradually expand, resulting in increased water damage to the road surface and further damage to the road surface structure. In order to improve the performance of asphalt and asphalt mixtures, domestic and foreign scholars have carried out a lot of research, among which modified asphalt technology has become an important means. Common modifiers can improve the high-temperature and low-temperature properties of asphalt to a certain extent, but there are problems such as high cost and limited modification effect.

[0003] Rubber powder modified asphalt is a technology with potential. It adds rubber powder from waste tires to asphalt, which can not only realize the resource utilization of waste tires, but also improve some properties of asphalt. However, the performance improvement of simple rubber powder modified asphalt is still insufficient, and the compatibility between rubber powder and asphalt needs to be improved. Nanomaterials show good application prospects in the field of modified asphalt due to their unique nano effect. The addition of nanomaterials can improve the microstructure of asphalt and enhance the mechanical properties and rheological properties of asphalt. However, the dispersion problem of nanomaterials in asphalt has always been a key factor restricting its modification effect. Therefore, it is of great significance and value to solve the problems existing in rubber powder and nanomaterials in asphalt modification. Summary of the invention

[0004] The invention provides a rubber powder grafted nano material composite modifier modified asphalt, in which the rubber powder is modified by amino modification and the nano material is modified by carboxyl modification.

[0005] The preparation method of the above-mentioned rubber powder grafted nano material composite modifier modified asphalt comprises the following steps:

[0006] (1) Amide modification of rubber powder

[0007] a. Preparation of rubber powder A

[0008] Adding an organic solvent to the rubber powder for extraction; after the extraction is completed, washing and drying, then adding an alkaline solution and stirring for reaction; after the reaction is completed, washing and drying to obtain rubber powder A;

[0009] b. Preparation of rubber powder B

[0010] Add the coupling agent to the organic solution and stir evenly to obtain a coupling agent solution; then add the rubber powder A and stir to react; after the reaction is completed, wash and dry to obtain the rubber powder B, i.e., the amino rubber powder;

[0011] (2) Carboxylation modification of nanomaterials

[0012] The nanomaterial is mixed with an organic solvent, ultrasonically dispersed, and then a surface modifier is added to react; after the reaction is completed, the nanomaterial is washed and dried to obtain a carboxylated nanomaterial;

[0013] (3) Aminated rubber powder grafted with carboxylated nanomaterials

[0014] The carboxyl nanomaterial is added to an organic solvent, dispersed by ultrasonic, and then the amino rubber powder is added, stirred evenly, and then the accelerator is added, and stirred to react; after the reaction is completed, the precipitate is taken and dried to obtain the amino rubber powder grafted carboxyl nanomaterial;

[0015] (4) Preparation of modified asphalt

[0016] The base asphalt is baked to a molten state, and the amino rubber powder is added to graft the carboxylated nanomaterials, stirred to react, and then high-speed shearing is performed, and finally stirring and developing is performed to obtain modified asphalt.

[0017] In the above preparation method, in step (1), the extraction time is selected from 1 to 3 hours; and the stirring reaction time is selected from 1 to 3 hours.

[0018] In the above preparation method, in the step (1), the rubber powder is selected from one or more of styrene-butadiene rubber powder, butadiene rubber, and nitrile rubber, and its particle size is 0.1-0.5 mm; the organic solvent is selected from one or more of acetone, toluene, dichloromethane, chloroform, cyclohexanone, ethyl acetate, methyl ethyl ketone, and tetrahydrofuran; the alkaline solution is one or more of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, and calcium hydroxide solution, and its concentration is 0.5-1.5 mol / L.

[0019] In the above preparation method, in the step (1), the coupling agent is selected from one or more of aminopropyltriethoxysilane, aminopropyltriethoxysilane, aminopropylmethyldimethoxysilane, aminopropyldimethylmethoxysilane, aminopropyldimethoxyethoxysilane, aminopropylmethyldiethoxysilane, aminopropyldimethylethoxysilane, aminopropylethyldimethoxysilane, aminopropyldiethylmethoxysilane, aminopropylethyldiethoxysilane, aminopropylmethoxydiethoxysilane, aminopropyldiethylethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0020] In the above preparation method, in step (1), the organic solution is a mixed solution of water and an organic solvent, wherein the organic solvent is selected from one or more of anhydrous ethanol, methanol, isopropanol, and acetone, and the mass ratio of the organic solvent to water is 1:2 to 3.

[0021] In the above preparation method, in step (2), the nanomaterial is selected from one or more of nano calcium carbonate, nano silicon dioxide, nano kaolin, nano aluminum oxide, nano titanium oxide, nano zinc oxide, carbon nanotubes, nano carbon fibers, graphene, graphene oxide, nano montmorillonite, graphite phase carbon nitride, molybdenum disulfide, titanium disulfide, and titanium diselenide, and its particle size is 10nm-1μm.

[0022] In the above preparation method, in step (2), the organic solvent is selected from one or more of anhydrous ethanol, methanol, isopropanol, and acetone.

[0023] In the above preparation method, in step (2), the surface modifier is selected from one or more of formic acid, acetic acid, caproic acid, acrylic acid, succinic acid, citraconic acid, mesaconic acid, itaconic acid, fumaric acid, maleic acid, malonic acid, lauric acid, oxalic acid, phthalic acid, isophthalic acid, citric acid, 1,3,5-benzenetricarboxylic acid, 1,2,3-benzenetricarboxylic acid, and oleic acid.

[0024] In the above preparation method, in step (2), the reaction conditions are selected from: stirring at 50-70° C. and condensing and refluxing for 2-4 h.

[0025] In the above preparation method, in step (3), the stirring reaction conditions are selected from: stirring the reaction at 40-70° C. for 3-6 hours.

[0026] In the above preparation method, in step (3), the organic solvent is selected from one or more of anhydrous ethanol, methanol, isopropanol, and acetone.

[0027] In the above preparation method, in step (3), the accelerator is selected from one or more of dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), carbonyldiimidazole (CDI), and tetramethylammonium chloride (TMAC).

[0028] In the above preparation method, in step (4), the matrix asphalt is selected from one or more of petroleum asphalt, rock asphalt, lake asphalt, and coal asphalt.

[0029] In the above preparation method, in step (4), the stirring reaction conditions are selected from: stirring at 170-190°C for 10-30 min; the high-speed shearing conditions are selected from: shearing at a rate of 4000-6000 r / min for 40-60 min; the stirring and developing conditions are selected from: developing at a stirring rate of 300-600 r / min for 1-2 h.

[0030] In the above preparation method, the raw materials in each step are selected from the following mass parts:

[0031] Step a in step (1): 10-30 parts of rubber powder, 200-400 parts of organic solvent, and 200-400 parts of alkaline solution; step b in step (1): 1.5-7.5 parts of coupling agent, 150-450 parts of organic solution, and 10-20 parts of rubber powder A; step (2): 1-10 parts of nanomaterial, 200-300 parts of organic solvent, and 0.5-5 parts of surface modifier; step (3): 1.5-15 parts of carboxylated nanomaterial, 150-450 parts of organic solvent, 10-20 parts of amino rubber powder, and 0.15-1.5 parts of accelerator; step (4): 200-800 parts of matrix asphalt, and 40-80 parts of amino rubber powder grafted with carboxylated nanomaterial;

[0032] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual applications, the portion number can be enlarged or reduced in proportion to the portion number.

[0033] In a specific embodiment, the raw materials in each step are selected from the following mass parts:

[0034] Step a in step (1): 20 parts of rubber powder, 200 parts of organic solvent, and 200 parts of alkaline solution; step b in step (1): 3 parts of coupling agent, 180 parts of organic solution, and 15 parts of rubber powder A; step (2): 5 parts of nanomaterial, 200 parts of organic solvent, and 2 parts of surface modifier; step (3): 5 parts of carboxylated nanomaterial, 250 parts of organic solvent, 15 parts of aminated rubber powder, and 0.6 parts of accelerator; step (4): 400 parts of base asphalt, and 48 parts of aminated rubber powder grafted with carboxylated nanomaterial;

[0035] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual applications, the portion number can be enlarged or reduced in proportion to the portion number.

[0036] The present invention provides the application of the rubber powder grafted nano material composite modifier modified asphalt in road engineering.

[0037] The present invention provides an asphalt mixture, which is composed of the following components in parts by weight:

[0038] 2000-6000 parts of coarse aggregate, 1500-3000 parts of fine aggregate, 200-600 parts of modified mineral powder, 200-600 parts of modified asphalt, 1-5 parts of anti-stripping agent;

[0039] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual applications, the portion number can be enlarged or reduced in proportion to the portion number.

[0040] In a specific embodiment, the asphalt mixture consists of the following components in parts by weight:

[0041] 4960 parts of coarse aggregate, 2240 parts of fine aggregate, 400 parts of modified mineral powder, 400 parts of modified asphalt, 2.5 parts of anti-stripping agent;

[0042] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual applications, the portion number can be enlarged or reduced in proportion to the portion number.

[0043] The above-mentioned asphalt mixture is prepared by the following method:

[0044] Coarse aggregate and fine aggregate are mixed, and dry-mixed for 30 to 60 seconds; then modified asphalt is added, and wet-mixed for 1 to 2 minutes; finally, modified mineral powder and anti-stripping agent are added, and stirred for 30 to 60 seconds to obtain an asphalt mixture.

[0045] In the above-mentioned asphalt mixture, among the coarse aggregate, the particle size of 16-26.5 mm accounts for 25-28%, the particle size of 9.5-16 mm accounts for 24-27%, and the particle size of 4.75-9.5 mm accounts for 10-13%; the anti-stripping agent is selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, acryloyloxyethyltrimethylammonium chloride, tetraethylenepentamine modified polybutyl acrylate, and 2-acrylamide-2-methylpropane sulfonic acid.

[0046] In the above-mentioned asphalt mixture, the modified mineral powder is prepared by the following method:

[0047] The polymer emulsion and the mineral powder are mixed, stirred at 50-70° C. at a stirring speed of 300-600 r / min for 30-60 min, and then dried at 100-120° C. for 3-5 h to constant weight to obtain modified mineral powder.

[0048] In the above-mentioned preparation method of modified mineral powder, the polymer emulsion is selected from one of SBS (styrene-butadiene-styrene block copolymer) emulsion, SEBS (hydrogenated styrene-butadiene-styrene block copolymer) emulsion, SBR (styrene-butadiene rubber) emulsion, EVA (ethylene-vinyl acetate copolymer) emulsion, and VAE (vinyl acetate-ethylene copolymer) emulsion; the mineral powder is selected from one of basalt, S75 granulated blast furnace slag powder, fly ash, red mud, S95 granulated blast furnace slag powder, coal gangue powder, and phosphogypsum, and its particle size is less than 0.075 mm.

[0049] In the above-mentioned preparation method of modified mineral powder, each raw material is selected from the following parts by weight: 50-300 parts of polymer emulsion, 200-600 parts of mineral powder;

[0050] When the component is a solid component, the portion number represents grams; when the component is a liquid component, the portion number represents milliliters; in actual applications, the portion number can be enlarged or reduced in proportion to the portion number.

[0051] The beneficial effects of the present invention are:

[0052] In the present invention, nanomaterials can limit the thermal motion of asphalt molecules, and rubber powder can also better combine with asphalt through grafting to enhance structural stability, thereby effectively reducing the flow and deformation of asphalt and improving the rutting resistance of the road surface. At low temperatures, it can improve the crystallization performance of asphalt, reduce the brittle point of asphalt, enable asphalt to maintain good flexibility at low temperatures, and reduce the cracking phenomenon caused by low-temperature shrinkage of the road surface.

[0053] Nanomaterial grafted rubber powder grafts flexible high molecular polymers onto the surface of rigid nanomaterials, achieving an effective combination of organic and inorganic materials, forming a stable chemical structure inside the asphalt, which can effectively prevent oxygen, moisture, etc. from contacting the asphalt and slow down the occurrence of oxidation reactions. Some nanomaterials also have good ultraviolet absorption capabilities, and the grafted rubber powder can also better disperse the nanomaterials in the asphalt, enhance the ability to resist ultraviolet rays, and reduce the impact of light aging.

[0054] Since the rubber powder grafted nanomaterial modified asphalt has good performance, the durability of the road paved with this material is improved, and the frequency of road maintenance and renovation is reduced. In the long run, it can significantly reduce the maintenance cost of roads and improve the efficiency of road use. In addition, the grafting modification of rubber powder prepared from waste tires can achieve high added value utilization of waste rubber, reduce the pollution of waste tires to the environment, meet the requirements of sustainable development, and also reduce the dependence of road construction on new resources.

[0055] The mineral powder modified by polymer emulsion is added to the asphalt mixture, which effectively improves the bonding force of the whole system, helps the aggregate to form physical entanglement and chemical adsorption with the asphalt molecules, makes the internal particles more tightly bound, effectively enhances the cohesion, and forms a more stable structure. At the same time, the polymer can provide a certain flexibility and deformation capacity for the asphalt mixture, reduce the cracks caused by temperature shrinkage, and significantly improve its low-temperature crack resistance, which can better adapt to the climate conditions in cold areas.

[0056] In summary, by grafting rubber powder with nanomaterials, the advantages of rubber powder and nanomaterials can be fully utilized, and the high temperature, low temperature, water stability and other properties of asphalt and asphalt mixtures can be significantly improved, providing new solutions for the high performance and sustainable development of asphalt pavements, thus having good application prospects and value in the field of road engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 FTIR graphs of original rubber powder and amino rubber powder;

[0058] Figure 2 FTIR images of carboxylated nano-silica and nano-silica;

[0059] Figure 3 is the complex shear modulus diagram of each modified asphalt;

[0060] Figure 4 The phase angle of each modified asphalt varies with temperature;

[0061] Figure 5 is the rutting factor of each modified asphalt;

[0062] Figure 6 is the creep stiffness of each modified asphalt;

[0063] Figure 7 is the creep rate of each modified asphalt;

[0064] Figure 8 is the softening point increment of each modified asphalt;

[0065] Fig. 9 is the rutting dynamic stability of each asphalt mixture;

[0066] Fig.10 is the failure strain of each asphalt mixture;

[0067] Fig.11 is the residual stability and freeze-thaw splitting strength ratio of each asphalt mixture. DETAILED DESCRIPTION

[0068] The base asphalt used in the following implementation of the present invention is No. 90 base asphalt produced by Qilu Petrochemical Company, and its relevant parameters are shown in Table 1.

[0069] Table 1

[0070] Test indicators unit Technical requirements Test data Test methods Needle penetration (25℃) 0.1mm 80-100 86 T0604 Softening point ℃ ≥45 47.9 T0604 Elongation (15℃) cm ≥100 ＞150 T0605

[0071] The coarse aggregate, fine aggregate and mineral powder used in the present invention are all basalt purchased from Zouping Basalt Co., Ltd.

[0072] Other materials used in the present invention, if not otherwise stated, can be obtained through commercial channels. Other terms used in the present invention, unless otherwise specified, generally have the meanings commonly understood by those of ordinary skill in the art. The present invention is further described in detail below in conjunction with specific examples and with reference to data. The following examples are only for illustrating the present invention, and are not intended to limit the scope of the present invention in any way.

[0073] Example 1

[0074] This embodiment relates to the preparation of asphalt modified by amino-butadiene styrene rubber powder grafted with carboxylated nano-silicon dioxide composite modifier and asphalt mixture.

[0075] 1. Preparation of amino-butadiene styrene rubber powder grafted carboxylated nano-silica composite modifier modified asphalt

[0076] (1) Amino modification of styrene-butadiene rubber powder

[0077] 20 g of styrene-butadiene rubber powder was placed in a Soxhlet extractor, 200 mL of acetone was added, and the powder was extracted for 2 h, washed with deionized water for 3 times, and dried in an oven at 70°C for 8 h, and then placed in a beaker filled with 200 mL of sodium hydroxide solution (1 mol / L) and stirred for 2 h, and then washed with deionized water for 3 times and dried at 70°C for 8 h to obtain rubber powder A;

[0078] Add 60 mL of acetone to 120 mL of distilled water, mix well to obtain an organic solution; add 3 g of aminopropyltriethoxysilane to the organic solution, stir for 1.5 hours to obtain a coupling agent solution; add 15 g of rubber powder A to the coupling agent solution, stir at a rate of 500 r / min for 3 hours, wash with deionized water 3 times, and place in a vacuum drying oven at 70°C to dry for 8 hours to obtain rubber powder B, i.e., amino-butadiene styrene rubber powder.

[0079] (2) Carboxylation modification of nano-silica

[0080] 5 g of nano-silica was added to 200 mL of anhydrous ethanol, ultrasonically dispersed for 15 min, 2 g of oxalic acid was added, placed in a magnetic stirrer, stirred at a constant temperature of 70°C, condensed and refluxed for 4 h, cooled to room temperature, and the precipitate was washed 3 times with anhydrous ethanol, filtered, and dried at 70°C for 8 h to obtain carboxylated nano-silica.

[0081] (3) Aminated styrene-butadiene rubber powder grafted with carboxylated nano-silica

[0082] 5 g of carboxylated nano-silica was added to 250 mL of anhydrous ethanol and ultrasonicated for 15 min, 15 g of amino-butadiene styrene rubber powder was added, stirred for 10 min, 0.6 g of dicyclohexylcarbodiimide was added, and the reaction was stirred at 60 ° C for 4 h. After cooling, the solid precipitate was taken out and placed in a vacuum oven at 60 ° C to dry. After constant weight, a composite modifier, i.e., amino-butadiene styrene rubber powder grafted with carboxylated nano-silica, was obtained.

[0083] (4) Preparation of modified asphalt

[0084] Heat 400g of base asphalt to a molten state, add 48g (12%) of amino-butadiene styrene rubber powder grafted carboxylated nano-silica composite modifier, stir at 180°C for 20min, then move to a shearing machine and shear at a rate of 5000r / min for 60min, finally stir and develop at 170°C at a rate of 500r / min for 1.5h to obtain amino-butadiene styrene rubber powder grafted carboxylated nano-silica modified asphalt.

[0085] 2. Preparation of asphalt mixture

[0086] 100 g of SBS emulsion and 400 g of basalt powder were added to a stirring kettle, stirred at 70°C and 500 r / min for 40 min, and then placed in an oven and dried at 120°C for 4 h to constant weight to obtain modified powder.

[0087] Place the coarse aggregate and fine aggregate in an oven at 180°C and dry for 2 hours; put 2080g of coarse aggregate with a particle size of 16-26.5mm, 2000g of coarse aggregate with a particle size of 9.5-16mm, 880g of coarse aggregate with a particle size of 4.75-9.5mm and 2240g of fine aggregate into a mixing pot and dry mix for 40 seconds, then add 400g of modified asphalt and wet mix for 90 seconds, finally add 400g of modified mineral powder and 2.5g of ethylenediamine, stir for 40 seconds to obtain an asphalt mixture.

[0088] Figure 1 The FTIR graphs of the original rubber powder and the amino-treated rubber powder are shown.

[0089] like Figure 1 As shown, the original rubber powder and the amino rubber powder are at 1077cm -1 There are absorption peaks at 3325cm, which are attributed to the vibration of OH. However, unlike the original rubber powder, the characteristic peak of the amino rubber powder is wider and stronger here, which is due to the superposition vibration of NH and OH. -1 The original rubber powder did not show an absorption peak, while the amino-modified rubber powder produced a bending vibration peak of NH. The above results show that the amino group was successfully modified on the surface of the rubber powder.

[0090] Figure 2 The FTIR graph of carboxylated nanosilica is shown.

[0091] like Figure 2 As shown in the figure, both nano-silica and carboxylated nano-silica are at 1050 cm -1 There is an absorption peak, which is attributed to the Si-O-Si stretching vibration. The carboxylated nano-silica has an absorption peak at 3431 cm -1 and 1625cm -1 New characteristic peaks are generated at , which are attributed to the stretching vibration of OH and C=O on the carboxyl group, indicating that the nano-silica is successfully modified with carboxyl groups.

[0092] Example 2

[0093] This embodiment relates to the preparation of asphalt modified by aminated styrene butadiene rubber powder grafted with carboxylated nano-silicon dioxide composite modifier and asphalt mixture. The difference from Example 1 is that in the preparation process of modified asphalt, the amount of aminated styrene butadiene rubber powder grafted with carboxylated nano-silicon dioxide composite modifier used is 56g (14%).

[0094] Example 3

[0095] This embodiment relates to the preparation of asphalt modified by aminated styrene butadiene rubber powder grafted with carboxylated nano-silicon dioxide composite modifier and asphalt mixture. The difference from Example 1 is that in the preparation of modified asphalt, the amount of aminated styrene butadiene rubber powder grafted with carboxylated nano-silicon dioxide composite modifier used is 64g (16%).

[0096] Example 4

[0097] This embodiment relates to the preparation of asphalt modified by amino-butadiene rubber powder grafted with carboxylated nano-titanium oxide composite modifier and asphalt mixture.

[0098] 1. Preparation of amino-butadiene rubber powder grafted carboxylated nano-titanium oxide composite modifier modified asphalt

[0099] (1) Amino modification of butadiene rubber powder

[0100] 20 g of cis-1,2-butadiene rubber powder was placed in a Soxhlet extractor, 200 mL of acetone was added, and the mixture was extracted for 2 h, washed with deionized water for 3 times, dried in an oven at 70°C for 8 h, and then placed in a beaker filled with 200 mL of potassium hydroxide solution (1 mol / L) and stirred for 2 h, and then washed with deionized water for 3 times and dried at 70°C for 8 h to obtain rubber powder A;

[0101] Add 60 mL of dichloromethane to 120 mL of distilled water, mix well to obtain an organic solution; add 4 g of aminopropyldimethoxyethoxysilane to the organic solution, stir for 2 hours to obtain a coupling agent solution; add 15 g of rubber powder A to the coupling agent solution, stir at a rate of 600 r / min for 3 hours, wash with deionized water 3 times, and place in a vacuum drying oven at 70°C to dry for 8 hours to obtain rubber powder B, i.e., aminobutyl rubber powder.

[0102] (2) Carboxylation modification of nano-titanium oxide

[0103] 5 g of nano-titanium oxide was added to 200 mL of anhydrous ethanol, ultrasonically dispersed for 15 min, 3 g of maleic acid was added, placed in a magnetic stirrer, stirred at a constant temperature of 70 ° C, condensed and refluxed for 3 h, cooled to room temperature, and the precipitate was washed 3 times with anhydrous ethanol, filtered, and dried at 70 ° C for 8 h to obtain carboxylated nano-titanium oxide.

[0104] (3) Aminated butadiene rubber powder grafted with carboxylated nano-titanium oxide

[0105] 5 g of carboxylated nano-titanium oxide was added to 250 mL of anhydrous ethanol and ultrasonicated for 20 min, 15 g of amino-butyl rubber powder was added, stirred for 15 min, 0.8 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide was added, and the mixture was stirred at 60 ° C for 3 h. After cooling, the solid precipitate was taken out and placed in a vacuum oven at 60 ° C for drying. After constant weight, a composite modifier was obtained, i.e., amino-butyl rubber powder grafted with carboxylated nano-titanium oxide.

[0106] (4) Preparation of modified asphalt

[0107] Heat 400g of base asphalt to a molten state, add 56g of amino-butyl rubber powder grafted carboxylated nano-titanium oxide composite modifier, stir at 180°C for 20min, then move to a shearing machine and shear at a rate of 5500r / min for 50min, finally stir and develop at 170°C at a rate of 500r / min for 2h to obtain amino-butyl rubber powder grafted carboxylated nano-titanium oxide modified asphalt.

[0108] 2. Preparation of asphalt mixture

[0109] 100 g of SBS emulsion and 400 g of basalt powder were added to a stirring kettle, stirred at 70°C and 500 r / min for 40 min, and then placed in an oven and dried at 120°C for 4 h to constant weight to obtain modified powder.

[0110] Place the coarse aggregate and fine aggregate in an oven at 180°C and dry for 2 hours; put 2160g of coarse aggregate with a particle size of 16-26.5mm, 1920g of coarse aggregate with a particle size of 9.5-16mm, 800g of coarse aggregate with a particle size of 4.75-9.5mm and 2320g of fine aggregate into a mixing pot and dry mix for 40 seconds, then add 400g of modified asphalt and wet mix for 90 seconds, finally add 400g of modified mineral powder and 2.5g of triethylenetetramine, stir for 30 seconds to obtain an asphalt mixture.

[0111] Comparative Example 1

[0112] This comparative example provides the above-mentioned unmodified No. 90 base asphalt produced by Qilu Petrochemical Company, and its relevant indicators are shown in Table 1.

[0113] To prepare asphalt mixture, the steps are as follows:

[0114] Place the coarse aggregate and fine aggregate in an oven at 180°C and dry for 2 hours; put 2080g of coarse aggregate with a particle size of 16-26.5mm, 2000g of coarse aggregate with a particle size of 9.5-16mm, 880g of coarse aggregate with a particle size of 4.75-9.5mm and 2240g of fine aggregate into a mixing pot and dry mix for 40s, then add 400g of base asphalt and wet mix for 90s, finally add 400g of basalt slag powder and 2.5g of ethylenediamine, stir for 40s to obtain an asphalt mixture.

[0115] Comparative Example 2

[0116] This comparative example involves the preparation of amino-styrene-butadiene rubber powder modified asphalt and asphalt mixture. The preparation method is as shown in the above-mentioned Example 1, and the difference from Example 1 is that the amount of carboxylated nano-silica used in this comparative example is 0g.

[0117] 1. Preparation of amino-butadiene styrene rubber powder modified asphalt

[0118] (1) Amino modification of styrene-butadiene rubber powder

[0119] 20 g of styrene-butadiene rubber powder was placed in a Soxhlet extractor, 200 mL of acetone was added, and the powder was extracted for 2 h, washed with deionized water for 3 times, and dried in an oven at 70°C for 8 h, and then placed in a beaker filled with 200 mL of sodium hydroxide solution (1 mol / L) and stirred for 2 h, and then washed with deionized water for 3 times and dried at 70°C for 8 h to obtain rubber powder A;

[0120] Add 60 mL of acetone to 120 mL of distilled water, mix well to obtain an organic solution; add 3 g of aminopropyltriethoxysilane to the organic solution, stir for 1.5 hours to obtain a coupling agent solution; add 15 g of rubber powder A to the coupling agent solution, stir at a rate of 500 r / min for 3 hours, wash with deionized water 3 times, and place in a vacuum drying oven at 70°C to dry for 8 hours to obtain rubber powder B, i.e., amino-butadiene styrene rubber powder.

[0121] (2) Preparation of modified asphalt

[0122] Heat 400g of base asphalt to a molten state, add 36g (9%) of amino-butadiene styrene rubber powder, stir at 180°C for 20min, then move to a shearing machine and shear at a rate of 5000r / min for 60min, and finally stir and develop at 170°C at a rate of 500r / min for 1.5h to obtain amino-butadiene styrene rubber powder modified asphalt.

[0123] 2. Preparation of asphalt mixture

[0124] 100 g of SBS emulsion and 400 g of basalt powder were added to a stirring kettle, stirred at 70°C and 500 r / min for 40 min, and then placed in an oven and dried at 120°C for 4 h to constant weight to obtain modified powder.

[0125] Place the coarse aggregate and fine aggregate in an oven at 180°C and dry for 2 hours; put 2080g of coarse aggregate with a particle size of 16-26.5mm, 2000g of coarse aggregate with a particle size of 9.5-16mm, 880g of coarse aggregate with a particle size of 4.75-9.5mm and 2240g of fine aggregate into a mixing pot and dry mix for 40 seconds, then add 400g of modified asphalt and wet mix for 90 seconds, finally add 400g of modified mineral powder and 2.5g of ethylenediamine, stir for 40 seconds to obtain an asphalt mixture.

[0126] Comparative Example 3

[0127] This comparative example involves the preparation of carboxylated nano-silicon dioxide modified asphalt and asphalt mixture. The preparation method is as shown in the above-mentioned Example 1, and the difference from Example 1 is that the amount of amino-butadiene styrene rubber powder used in this comparative example is 0g.

[0128] 1. Preparation of carboxylated nano-silica modified asphalt

[0129] (1) Carboxylation modification of nano-silica

[0130] 5 g of nano-silica was added to 200 mL of anhydrous ethanol, ultrasonically dispersed for 15 min, 2 g of oxalic acid was added, placed in a magnetic stirrer, stirred at a constant temperature of 70°C, condensed and refluxed for 4 h, cooled to room temperature, and the precipitate was washed 3 times with anhydrous ethanol, filtered, and dried at 70°C for 8 h to obtain carboxylated nano-silica.

[0131] (2) Preparation of modified asphalt

[0132] Heat 400g of base asphalt to a molten state, add 12g (3%) carboxylated nano-silica, stir at 180°C for 20min, then move to a shearing machine and shear at a rate of 5000r / min for 60min, and finally stir and develop at 170°C at a rate of 500r / min for 1.5h to obtain carboxylated nano-silica modified asphalt.

[0133] 2. Preparation of asphalt mixture

[0134] 100 g of SBS emulsion and 400 g of basalt powder were added to a stirring kettle, stirred at 70°C and 500 r / min for 40 min, and then placed in an oven and dried at 120°C for 4 h to constant weight to obtain modified powder.

[0135] Place the coarse aggregate and fine aggregate in an oven at 180°C and dry for 2 hours; put 2080g of coarse aggregate with a particle size of 16-26.5mm, 2000g of coarse aggregate with a particle size of 9.5-16mm, 880g of coarse aggregate with a particle size of 4.75-9.5mm and 2240g of fine aggregate into a mixing pot and dry mix for 40 seconds, then add 400g of modified asphalt and wet mix for 90 seconds, finally add 400g of modified mineral powder and 2.5g of ethylenediamine, stir for 40 seconds to obtain an asphalt mixture.

[0136] Comparative Example 4

[0137] This comparative example involves the preparation of amino-butadiene styrene rubber powder / carboxylated nano-silicon dioxide modified asphalt and asphalt mixture. The preparation method is as shown in the above-mentioned Example 1, and the difference from Example 1 is that the amino-butadiene styrene rubber powder and carboxylated nano-silicon dioxide are not grafted in this comparative example.

[0138] 1. Preparation of amino-butadiene styrene rubber powder / carboxylated nano-silica modified asphalt

[0139] (1) Amino modification of styrene-butadiene rubber powder

[0140] 20 g of styrene-butadiene rubber powder was placed in a Soxhlet extractor, 200 mL of acetone was added, and the powder was extracted for 2 h, washed with deionized water for 3 times, and dried in an oven at 70°C for 8 h, and then placed in a beaker filled with 200 mL of sodium hydroxide solution (1 mol / L) and stirred for 2 h, and then washed with deionized water for 3 times and dried at 70°C for 8 h to obtain rubber powder A;

[0141] Add 60 mL of acetone to 120 mL of distilled water, mix well to obtain an organic solution; add 3 g of aminopropyltriethoxysilane to the organic solution, stir for 1.5 hours to obtain a coupling agent solution; add 15 g of rubber powder A to the coupling agent solution, stir at a rate of 500 r / min for 3 hours, wash with deionized water 3 times, and place in a vacuum drying oven at 70°C to dry for 8 hours to obtain rubber powder B, i.e., amino-butadiene styrene rubber powder.

[0142] (2) Carboxylation modification of nano-silica

[0143] 5 g of nano-silica was added to 200 mL of anhydrous ethanol, ultrasonically dispersed for 15 min, 2 g of oxalic acid was added, placed in a magnetic stirrer, stirred at a constant temperature of 70°C, condensed and refluxed for 4 h, cooled to room temperature, and the precipitate was washed 3 times with anhydrous ethanol, filtered, and dried at 70°C for 8 h to obtain carboxylated nano-silica.

[0144] (3) Preparation of modified asphalt

[0145] Heat 400g of base asphalt to a molten state, add 36g (9%) amino-butadiene styrene rubber powder and 12g (3%) carboxylated nano-silica, stir at 180°C for 20min, then move to a shearing machine and shear at a rate of 5000r / min for 60min, finally stir and develop at 170°C at a rate of 500r / min for 1.5h to obtain amino-butadiene styrene rubber powder / carboxylated nano-silica modified asphalt.

[0146] 2. Preparation of asphalt mixture

[0147] 100 g of SBS emulsion and 400 g of basalt powder were added to a stirring kettle, stirred at 70°C and 500 r / min for 40 min, and then placed in an oven and dried at 120°C for 4 h to constant weight to obtain modified powder.

[0148] Place the coarse aggregate and fine aggregate in an oven at 180°C and dry for 2 hours; put 2080g of coarse aggregate with a particle size of 16-26.5mm, 2000g of coarse aggregate with a particle size of 9.5-16mm, 880g of coarse aggregate with a particle size of 4.75-9.5mm and 2240g of fine aggregate into a mixing pot and dry mix for 40 seconds, then add 400g of modified asphalt and wet mix for 90 seconds, finally add 400g of modified mineral powder and 2.5g of ethylenediamine, stir for 40 seconds to obtain an asphalt mixture.

[0149] Comparative Example 5

[0150] This comparative example involves the preparation of amino-butadiene styrene rubber powder grafted carboxylated nano-silicon dioxide composite modifier modified asphalt and asphalt mixture. The preparation method is as shown in the above-mentioned Example 1, and the difference from Example 1 is that unmodified mineral powder is used in the preparation of the asphalt mixture of this comparative example.

[0151] 1. Performance testing and evaluation of modified asphalt

[0152] Indicators such as penetration, ductility, softening point and separation softening point difference are basic performance indicators of asphalt. According to the requirements of "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the present invention tests the influence of the rubber powder grafted nanomaterial composite modifier added to asphalt on the basic performance indicators of asphalt.

[0153] 1. Softening point, ductility, penetration and segregation softening point difference

[0154] The test results are shown in Table 2.

[0155] Table 2

[0156]

[0157] Softening point is an important indicator of thermal stability of asphalt materials. As can be seen from Table 2, compared with Comparative Example 1, the softening points of the comparative examples and examples after adding the modifier are significantly improved. The highest softening point in the comparative examples is 58.6°C in Comparative Example 4, that is, the rubber powder and nanomaterials are co-mixed to modify the asphalt. The softening point in the examples is as low as 62.5°C in Example 1 and as high as 64.6°C in Example 2, indicating that the softening point of the amino rubber powder and carboxylated nanomaterials used to modify asphalt after grafting is better than the single and co-mixed of the two, and it is not easy to soften and deform in a high temperature environment, which is more conducive to the performance of the road surface in high temperature seasons. Among them, compared with Examples 1 and 3, Examples 2 and 4 have higher softening points, indicating that the modifier dosage is better at 14%.

[0158] The penetration can characterize the consistency of asphalt and indirectly reflect the hardness of asphalt. The penetration of the examples and comparative examples 2-4 in Table 2 has decreased, but the decrease in the examples is more significant, with the lowest being 63.5 (0.1 mm) in example 3 and the lowest being 68.2 (0.1 mm) in comparative example 4, indicating that the addition of the modifier improves the penetration of asphalt, and the use of the modifier for modified asphalt after grafting is significantly better than single and multiple additions, which also shows that the examples have greater hardness and better ability to resist external deformation at room temperature.

[0159] Ductility is an indicator of asphalt flexibility and crack resistance. A higher ductility value means that asphalt has better flexibility and deformation ability at low temperatures, can adapt to the shrinkage stress caused by temperature changes, and reduce the possibility of low-temperature cracking of the road surface. At 5°C, compared with Comparative Example 1, the ductility of Example 1 and Comparative Examples 2-4 increased significantly, with the increase in Example 1 being greater, with the maximum being 37.1 cm in Example 4 and the minimum being 35.3 cm in Example 1. The maximum ductility of the comparative example is 30.2 cm in Example 4, indicating that the ductility of the modified asphalt after the rubber powder is grafted with the nanomaterial is better, and is best when the modifier dosage is 14%.

[0160] Segregation softening point difference is a key indicator for evaluating the uniformity of polymer modified asphalt, reflecting the quality of the anti-segregation performance of modified asphalt during storage. The smaller the softening point difference, the better its storage performance. From the data in Table 2, it can be seen that although the softening point difference of the embodiment and the comparative example meet the requirements of the specification, the segregation softening point difference of the embodiment can reach as low as 0.63°C in Example 4 and as high as 1.09°C in Example 1, while the lowest in the comparative example is 1.98°C in Comparative Example 4. It can be seen that when the rubber powder and nanomaterials are mixed, the storage performance of the modified asphalt can be improved, but after the two are grafted, the storage performance is significantly improved, indicating that the modified asphalt modified by the grafted modifier is not prone to polymer floating or sinking during the 48h storage process, and can maintain good performance stability, and the compatibility of the internal polymer and asphalt is better. Among them, the best is achieved when the dosage of the modifier in the embodiment is 14%.

[0161] 2. Complex shear modulus and phase angle

[0162] Figure 3 and Figure 4 They are the detection results of complex shear modulus and phase angle respectively.

[0163] The complex shear modulus is an important indicator for characterizing the viscoelasticity of asphalt. It comprehensively reflects the ability of asphalt to resist deformation under dynamic shear. The larger the value, the stronger the ability of asphalt to resist deformation. The phase angle reflects the phase difference between stress and strain of asphalt under dynamic shear load. Its value is closely related to the viscosity and elastic properties of asphalt. Among them, the larger the complex shear modulus and the smaller the phase angle, the less likely the asphalt is to undergo permanent deformation, and it has better high-temperature rheological properties.

[0164] Depend on Figure 3 and Figure 4 It can be seen that as the temperature rises, the complex shear modulus of each comparative example and embodiment shows a downward trend, and the phase angle shows an increasing trend. This is because when the temperature rises, the thermal motion of the asphalt molecules intensifies, the intermolecular force weakens, the viscosity of the asphalt decreases, and the ability to resist deformation decreases. At the same temperature, compared with comparative example 1, after adding different functionalized modifiers in comparative examples 2 to 4, the complex shear modulus increases and the phase angle decreases. Among them, after adding two modifiers, amino rubber powder and carboxyl nanomaterial, to comparative example 4, the improvement effect of the complex shear modulus and phase angle is significantly better than that of comparative examples 2 and 3, indicating that the addition of the two modifiers is more conducive to improving the performance of asphalt. After adding the grafted modifier in the embodiment, compared with comparative example 4 with the best effect in the comparative example, the complex modulus and phase angle are further increased and decreased, respectively, and the effect is very significant, indicating that the asphalt modified by the grafted modifier has a stronger ability to resist deformation under dynamic shear, which means that its high temperature performance is better and it is less likely to have deformation diseases such as rutting under high temperature conditions.

[0165] 3. Rutting factor

[0166] Figure 5 The changes of the rutting factors of the embodiments and the comparative examples are shown.

[0167] The rutting factor is a key indicator for evaluating the high-temperature performance of asphalt. It is the ratio between the complex shear modulus and the sine value of the phase angle, reflecting the ability of asphalt to resist rutting deformation under high temperature and repeated loads. The larger the rutting factor value, the stronger the asphalt's ability to resist rutting.

[0168] from Figure 5It can be seen that as the temperature rises, the rutting factors of all comparative examples and examples show a downward trend. From comparative examples 2-3 and comparative example 4, it can be seen that the composite admixture is better than the single admixture modified asphalt, and in the comparison between comparative example 4 and the example, the performance of the grafted asphalt is significantly better than the ungrafted rubber powder and nanomaterial. This is because the grafted composite modifier combines with the asphalt to enhance the cohesive force, so that it has sufficient ability to resist external forces. The anti-rutting performance of the asphalt in the example is relatively less sensitive to temperature changes. In areas with large temperature changes, it is more conducive to maintaining good performance of the road surface, which is consistent with the above analysis of the complex shear modulus and phase angle, and Examples 2 and 4 are the best.

[0169] 4. Low temperature rheological properties

[0170] Figure 6 and Figure 7 The changes of creep stiffness (S) and creep rate (m) are shown respectively.

[0171] Creep stiffness (S) is an important indicator for measuring asphalt's ability to resist deformation under low temperature conditions. It reflects the ease with which asphalt deforms under constant stress. The larger the value, the harder the asphalt is at low temperatures and the stronger its ability to resist deformation, but it may also be more prone to cracking. The creep rate (m) characterizes the speed at which asphalt's deformation changes over time at low temperatures, reflecting the viscoelastic properties of asphalt. The larger the creep rate, the faster the deformation of asphalt develops at low temperatures, the more viscous components the material has, and some stress can be relieved through viscous flow at low temperatures.

[0172] Depend on Figure 6 and Figure 7 It can be seen that the creep stiffness of Comparative Examples 2-4 is lower than that of Comparative Example 1, and Comparative Example 4 < Comparative Example 2 < Comparative Example 3; the creep rate is increased, and Comparative Example 4 > Comparative Example 2 > Comparative Example 3, indicating that the single addition of rubber powder is better than the single addition of nanomaterials, and the combined addition of rubber powder and nanomaterials is better than the single addition of the two. This may be due to the insufficient crosslinking of the single-addition modifier with asphalt, and the chemical bonding reaction with the asphalt component is not completely generated, while the combined addition of the amino rubber powder and carboxylated nanomaterials added in Comparative Example 4 can play a certain synergistic role. In the examples, the improvement of creep stiffness and creep rate is more significant, and both are the best in Examples 2 and 4, indicating that the grafted modifier is better than the asphalt modified by the combined modifier, because the amino rubber powder and the carboxylated nanomaterials are grafted to form a stable crosslinked network structure, which improves rigidity while also having better flexibility, and can adapt to the shrinkage stress caused by temperature changes to a certain extent, reducing the risk of low-temperature cracking, thereby improving low-temperature crack resistance.

[0173] 5. Anti-aging performance evaluation

[0174] Figure 8The change in softening point increment of the embodiments and comparative examples is shown.

[0175] The softening point increment is an important indicator for evaluating the aging performance of asphalt. It reflects the change in the softening point of asphalt after aging and reflects the asphalt's ability to resist aging. The larger the softening point increment, the higher the degree of hardening of the asphalt after aging, and the more obvious its performance degradation.

[0176] Depend on Figure 8 It can be seen that, whether it is heat aging or light-heat coupling aging, the softening points of each comparative example and embodiment have different degrees of increment. Under the same aging method, the softening point increment of comparative example 4 is lower than that of comparative examples 2 and 3, and the embodiment is even lower, indicating that the asphalt mixed with amino rubber powder and carboxyl nanomaterial alone becomes harder after aging, and the degree of performance degradation is relatively high, and the mixed with the two is second. In contrast, the asphalt of the embodiment has better anti-aging performance, and Examples 2 and 4 are the best. The grafted composite modifier can block part of the conduction of light and heat and diffusion in the asphalt system, making the light components in the asphalt evaporate more slowly. The modified asphalt prepared by the grafted composite modifier can better improve the anti-aging performance of the modified asphalt, and can better maintain its own stability and road performance in the face of environmental factors such as heat and light.

[0177] 2. Asphalt mixture testing and evaluation

[0178] The road performance of the asphalt mixtures in the above implementation cases were tested in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The test results and analysis are shown below.

[0179] 1. High temperature stability

[0180] Fig. 9 The changes in rutting dynamic stability of the embodiment and the comparative example are shown.

[0181] Rutting dynamic stability is a key indicator for evaluating the high-temperature rutting resistance of asphalt mixtures. The higher the dynamic stability value, the stronger the asphalt mixture's ability to resist rutting deformation.

[0182] from Fig. 9It can be seen that the rutting dynamic stability of Examples 1-4 is significantly higher than that of Comparative Examples 1-5. The rutting dynamic stability values ​​of Examples 1-4 are between 5000 and 5725 times / mm, while the rutting dynamic stability of Comparative Examples 1-4 is between 1569 and 4129 times / mm. The dynamic stability of the asphalt mixture after the aminated rubber powder is grafted with the carboxylated nanomaterial composite modifier is greatly improved. This is because the aminated rubber powder and the carboxylated nanomaterial form a more stable cross-linked network structure with the asphalt after grafting, which is more compact in the mixture and has a stronger ability to resist rutting deformation under high temperature and repeated loads. By comparing comparative examples 2-4 with the embodiments, it is shown that the modified asphalt mixture prepared by the grafted composite modifier is significantly better than the composite and single modifiers; by comparing comparative example 5 with the embodiments, it is shown that the mineral powder modified by the polymer emulsion has become a strong chemical bond between asphalt and aggregate, enhancing the adhesion between the two and the cohesion of the asphalt mixture, and further improving the high temperature performance of the asphalt mixture.

[0183] 2. Low temperature crack resistance

[0184] Fig.10 The changes in the failure strain of the embodiments and the comparative examples are shown.

[0185] Low temperature bending test is used to evaluate the low temperature performance of asphalt mixture. The greater the failure strain, the greater the deformation that the asphalt mixture can withstand before failure, the better the toughness of the material, and the stronger its ability to resist cracking.

[0186] Depend on Fig.10 It can be seen that compared with comparative examples 1-4, the failure strain of comparative example 5 and embodiment 1-4 is significantly improved, and the ability to resist cracking in low temperature environment is stronger. This is because the amino rubber powder grafted carboxylated nano-material composite modifier provides a stable network structure for the asphalt mixture, which can prevent relative slip between aggregates, and can effectively transmit and dissipate stress, thereby reducing stress concentration and cracking. Compared with comparative example 5, the improvement of the failure strain of embodiment 1-4 is more significant. This is because the polymer has a certain toughness and tensile strength. The mineral powder modified by the polymer emulsion has a stronger bonding effect with asphalt and aggregates, forming physical entanglement and chemical adsorption with them, and the internal particles are more tightly bonded. In a low temperature environment, it can produce greater deformation before being destroyed by external forces, and has better toughness and low temperature cracking resistance. Among them, the failure strain of embodiments 2 and 4 reaches the maximum value, indicating that the optimal dosage of the amino rubber powder grafted nano-material composite modifier is 14%, which is consistent with the previous analysis.

[0187] 3. Water stability

[0188] Fig.11 The changes in residual stability and freeze-thaw splitting strength ratio of the embodiments and comparative examples are shown.

[0189] Residual stability and freeze-thaw splitting tensile strength ratio are important indicators for evaluating the water stability of asphalt mixtures. The higher the residual stability and freeze-thaw splitting tensile strength ratio, the better the water stability of the mixture.

[0190] Depend on Fig.11 It can be seen that the residual stability and freeze-thaw splitting tensile strength ratio of Examples 1-4 and Comparative Example 5 are higher than those of Comparative Example 1-4, indicating that the asphalt mixture modified by the grafted composite modifier can better maintain its strength under the erosion of water and after experiencing freeze-thaw cycles, and its ability to resist water damage is enhanced and has better resistance to freeze-thaw damage. Compared with Comparative Example 5, the residual stability and freeze-thaw splitting tensile strength ratio of Examples 1-4 are significantly improved. This is because after the mineral powder is modified by the polymer emulsion, the polymer is firmly wrapped on the surface of the mineral powder, forming a hydrophobic film structure with a certain thickness on the surface of the mineral powder, which can effectively prevent moisture from entering the interface between asphalt and mineral powder. In a low temperature environment, its toughness can also play a role in preventing cracks from being generated and expanding. When applied in actual engineering, it can more effectively improve the durability of the road surface, greatly reduce water damage and freeze-thaw damage, and has significant engineering application value.

[0191] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A rubber powder grafted nano material composite modifier modified asphalt, characterized in that: In the modified asphalt, the rubber powder is modified by amino, and the nano material is modified by carboxyl.

2. The modified asphalt according to claim 1, characterized in that The preparation method of the modified asphalt comprises the following steps: (1) Amide modification of rubber powder a. Preparation of rubber powder A Adding an organic solvent to the rubber powder for extraction; after the extraction is completed, washing and drying, then adding an alkaline solution and stirring for reaction; after the reaction is completed, washing and drying to obtain rubber powder A; b. Preparation of rubber powder B Add the coupling agent to the organic solution and stir evenly to obtain a coupling agent solution; then add the rubber powder A and stir to react; after the reaction is completed, wash and dry to obtain the rubber powder B, i.e., the amino rubber powder; (2) Carboxylation modification of nanomaterials The nanomaterial is mixed with an organic solvent, ultrasonically dispersed, and then a surface modifier is added to react; after the reaction is completed, the nanomaterial is washed and dried to obtain a carboxylated nanomaterial; (3) Aminated rubber powder grafted with carboxylated nanomaterials The carboxyl nanomaterial is added to an organic solvent, dispersed by ultrasonic, and then the amino rubber powder is added, stirred evenly, and then the accelerator is added, and stirred to react; after the reaction is completed, the precipitate is taken and dried to obtain the amino rubber powder grafted carboxyl nanomaterial; (4) Preparation of modified asphalt The base asphalt is baked to a molten state, and the amino rubber powder is added to graft the carboxylated nanomaterials, stirred to react, and then high-speed shearing is performed, and finally stirring and developing is performed to obtain modified asphalt.

3. The modified asphalt according to claim 2, characterized in that: In the step (1): The rubber powder is selected from one or more of styrene-butadiene rubber powder, butadiene rubber, and nitrile rubber; the organic solvent is selected from one or more of acetone, toluene, dichloromethane, chloroform, cyclohexanone, ethyl acetate, methyl ethyl ketone, and tetrahydrofuran; the alkaline solution is one or more of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, and calcium hydroxide solution; The coupling agent is selected from one or more of aminopropyltriethoxysilane, aminopropyltriethoxysilane, aminopropylmethyldimethoxysilane, aminopropyldimethylmethoxysilane, aminopropyldimethoxyethoxysilane, aminopropylmethyldiethoxysilane, aminopropyldimethylethoxysilane, aminopropylethyldimethoxysilane, aminopropyldiethylmethoxysilane, aminopropylethyldiethoxysilane, aminopropylmethoxydiethoxysilane, aminopropyldiethylethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; The organic solution is a mixed solution of water and an organic solvent, wherein the organic solvent is selected from one or more of anhydrous ethanol, methanol, isopropanol, and acetone, and the mass ratio of the organic solvent to water is 1:2-3.

4. The modified asphalt according to claim 2, characterized in that: In the step (2): The nanomaterial is selected from one or more of nano calcium carbonate, nano silicon dioxide, nano kaolin, nano aluminum oxide, nano titanium oxide, nano zinc oxide, carbon nanotubes, nano carbon fibers, graphene, graphene oxide, nano montmorillonite, graphite phase carbon nitride, molybdenum disulfide, titanium disulfide, and titanium diselenide; The organic solvent is selected from one or more of anhydrous ethanol, methanol, isopropanol and acetone; The surface modifier is selected from one or more of formic acid, acetic acid, caproic acid, acrylic acid, succinic acid, citraconic acid, mesaconic acid, itaconic acid, fumaric acid, maleic acid, malonic acid, lauric acid, oxalic acid, phthalic acid, isophthalic acid, citric acid, 1,3,5-benzenetricarboxylic acid, 1,2,3-benzenetricarboxylic acid, and oleic acid.

5. The modified asphalt according to claim 2, characterized in that: In the step (3): The organic solvent is selected from one or more of anhydrous ethanol, methanol, isopropanol, and acetone; the accelerator is selected from one or more of dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), carbonyldiimidazole (CDI), and tetramethylammonium chloride (TMAC).

6. The modified asphalt according to claim 2, characterized in that: In the step (2), the reaction conditions are selected from: stirring at 50-70°C and condensing and refluxing for 2-4 hours; in the above preparation method, in the step (3), the stirring reaction conditions are selected from: stirring at 40-70°C for 3-6 hours; in the step (4), the stirring reaction conditions are selected from: stirring at 170-190°C for 10-30 minutes, the high-speed shearing conditions are selected from: shearing at a rate of 4000-6000 r / min for 40-60 minutes, and the stirring and developing conditions are selected from: developing at a stirring rate of 300-600 r / min for 1-2 hours.

7. The modified asphalt according to claim 2, characterized in that: The raw materials in each step are selected from the following mass parts: Step a in step (1): 10-30 parts of rubber powder, 200-400 parts of organic solvent, and 200-400 parts of alkaline solution; step b in step (1): 1.5-7.5 parts of coupling agent, 150-450 parts of organic solution, and 10-20 parts of rubber powder A; step (2): 1-10 parts of nanomaterial, 200-300 parts of organic solvent, and 0.5-5 parts of surface modifier; step (3): 1.5-15 parts of carboxylated nanomaterial, 150-450 parts of organic solvent, 10-20 parts of aminated rubber powder, and 0.15-1.5 parts of accelerator; step (4): 200-800 parts of matrix asphalt, and 40-80 parts of aminated rubber powder grafted with carboxylated nanomaterial.

8. Use of the rubber powder grafted nanomaterial composite modifier modified asphalt according to any one of claims 1 to 7 in road engineering.

9. An asphalt mixture, characterized in that: The asphalt mixture is composed of the following components in parts by mass: 2000-6000 parts of coarse aggregate, 1500-3000 parts of fine aggregate, 200-600 parts of modified mineral powder, 200-600 parts of rubber powder grafted nano material composite modifier modified asphalt, and 1-5 parts of anti-stripping agent.

10. The asphalt mixture according to claim 9, characterized in that: The asphalt mixture is prepared by the following method: The coarse aggregate and the fine aggregate are mixed and dry-mixed for 30 to 60 seconds; then, the rubber powder grafted nano-material composite modifier is added to modify the asphalt and wet-mixed for 1 to 2 minutes; finally, the modified mineral powder and the anti-stripping agent are added and stirred for 30 to 60 seconds to obtain the asphalt mixture.

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