Recycled asphalt concrete and preparation method thereof

Abstract

The invention relates to the technical field of asphalt concrete, and discloses recycled asphalt concrete and a preparation method thereof.The recycled asphalt concrete is prepared from, by mass, 70-80 parts of new asphalt, 10-15 parts of limestone, 5-10 parts of basalt, 3-8 parts of mineral powder, 40-60 parts of recycled asphalt mixture, 1-5 parts of reinforcing filler and 3-6 parts of thermosetting resin. The waste edible oil-loaded oxidized bagasse fiber, the porous carbon nitride nanosheet-loaded diatomite and tetraethyl silicate are mixed and reacted to form a reinforcing filler with a cross-linked network structure, the waste edible oil-loaded oxidized bagasse fiber is used as an aerogel skeleton structure, and the surface contains a long-chain alkane structure in the waste edible oil, so that the strength of the aerogel is enhanced. The aerogel interacts with the new asphalt and the old asphalt, so that the aerogel is filled into the asphalt, and the reinforcing filler with a cross-linked network structure has relatively high mechanical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt concrete, and specifically to a recycled asphalt concrete and a preparation method thereof. Background Art

[0002] Asphalt concrete is obtained after mineral mixture and asphalt binder are mixed and compacted. It is one of the main materials for modern road pavement structures, widely used in various road pavements, especially suitable for high-speed driving road pavements. Asphalt concrete pavement has good mechanical properties and road performance, with a flat and seamless pavement, shock absorption and low noise, comfortable driving, high traffic safety, etc. Moreover, the asphalt pavement can realize the recycling of pavement materials, so it is favored by designers and constructors in highway construction.

[0003] Combining new asphalt with waste asphalt mixture, adding new aggregates, additives, etc., the prepared recycled asphalt concrete realizes the recycling of waste asphalt mixture. However, the continuous aging of waste asphalt mixture makes it hard and brittle, and its viscoelastic properties deteriorate, resulting in easy aging and cracking of recycled asphalt concrete, and poor compatibility between new and old asphalt, leading to potholes on the recycled asphalt concrete pavement not long after use. Summary of the Invention

[0004] The present invention provides a recycled asphalt concrete and a preparation method thereof, which solve the problems of poor compatibility between new and old asphalt in recycled asphalt concrete and continuous aging of waste asphalt mixture.

[0005] The technical solution of the present invention:

[0006] A recycled asphalt concrete, comprising the following raw materials in parts by mass: 70 - 80 parts of new asphalt, 10 - 15 parts of limestone, 5 - 10 parts of basalt, 3 - 8 parts of mineral powder, 40 - 60 parts of recycled asphalt mixture, 1 - 5 parts of reinforcing filler, 3 - 6 parts of thermosetting resin;

[0007] The reinforcing filler is obtained by mixing and reacting epoxidized waste cooking oil, polyethylene glycol and oxidized sugarcane fiber, and then mixing with diatomite loaded with porous carbon nitride nanosheets and tetraethyl orthosilicate;

[0008] The epoxidized waste cooking oil is obtained by screening and filtering waste cooking oil, treating it with an alkaline solution, and then mixing it with a mixed solution;

[0009] The diatomite loaded with porous carbon nitride nanosheets is obtained by treating diatomite with acid, mixing it with melamine and β - cyclodextrin, and then calcining it at high temperature;

[0010] Furthermore, a preparation method of a recycled asphalt concrete comprises the following steps:

[0011] S1. Place the new asphalt in a mixing pot, heat it to 95 - 105 °C while stirring to obtain preheated asphalt. Mix limestone, basalt, and mineral powder, stir at 160 - 180 °C for 5 - 10 min, add the preheated asphalt, and continue stirring for 5 - 10 min to obtain a mixture.

[0012] S2. Mix the recycled asphalt mixture and the reinforcing filler, stir at 130 - 150 °C for 5 - 10 min, add the mixture and the thermosetting resin, and stir at 100 - 110 °C for 3 - 5 min to obtain recycled asphalt concrete.

[0013] Further, the new asphalt is 70# base asphalt.

[0014] Further, the particle size of the recycled asphalt mixture is 3.2 - 4.3 mm.

[0015] Further, the apparent density of basalt is 2.7 - 3.1 g / cm 3 , the water absorption rate is 1.5 - 1.6%, the crushing value is 15.2 - 17.3%, and the particle size is 8 - 10 mm.

[0016] Further, the crushing value index of limestone is grade two, the compressive strength is 80 - 100 MPa, and the particle size is 1 - 3 mm.

[0017] Further, the mineral powder is S95 - grade mineral powder, the apparent density is 2.6 - 2.7 g / cm 3 , the specific surface area is 450 - 500 m 2 / kg, the water content is 0.2 - 1%, and the particle size is 3.2 - 4.3 mm.

[0018] Further, the reinforcing filler is specifically prepared by the following steps:

[0019] A1. Add diatomite to a nitric acid solution with a concentration of 3 - 5 mol / L, stir evenly, stir - treat at 75 - 85 °C for 4 - 5 h, cool to room temperature, filter, wash, and dry to obtain acid - treated diatomite.

[0020] A2. Add melamine and β - cyclodextrin to deionized water, stir at 500 - 600 r / mim for 30 - 40 min, add the acid - treated diatomite, stir evenly, place it in a hydrothermal kettle, stir - react at 170 - 190 °C for 20 - 24 h, cool to room temperature, filter, wash, dry, place it in a muffle furnace, calcine at 500 - 600 °C for 2 - 3 h, cool to room temperature, take it out to obtain diatomite loaded with porous carbon nitride nanosheets.

[0021] A3. Screen the waste cooking oil through a sieve with 300 - 500 meshes to remove large particles, preheat it to 100 °C, add an alkaline solution to adjust the pH to 8 - 9, place it in a water bath at 100 °C, stir for 20 min, and after standing, remove the upper organic oil phase glycerol to obtain pretreated waste cooking oil;

[0022] A4. Mix the mixed solution and the pretreated waste cooking oil, and place them in an oil bath. Heat to 45 - 55 °C and stir at a rate of 80 - 120 r / min for 3 - 5 h. Then continue to heat to 120 - 125 °C, remove the moisture, and cool to room temperature to obtain epoxidized waste cooking oil;

[0023] A5. Mix the epoxidized waste cooking oil and polyethylene glycol, stir evenly, add p - toluenesulfonic acid, and stir and react at 80 - 100 °C for 1 - 2 h. Then cool to 70 - 80 °C, add ethanol and oxidized sugarcane bagasse fiber and mix, stir and react for 8 - 10 h, and then stir at 90 - 100 °C until the organic solvent ethanol volatilizes, and cool to room temperature to obtain modified sugarcane bagasse fiber;

[0024] A6. Mix deionized water, tetraethyl orthosilicate and ethanol mixture, stir evenly, add hydrochloric acid to adjust the pH to 2 - 3, stir evenly, add modified sugarcane bagasse fiber and diatomite loaded with porous carbon nitride nanosheets, stir, and adjust the pH to 6 - 8 with ammonia water, stand to form a gel. After the gel is aged, it is freeze - dried to obtain an enhanced filler.

[0025] Furthermore, during the above - mentioned A1 reaction process, the diatomite is treated with nitric acid, so that impurities such as Al 3+ 、Fe 3+ 、Ca 2 + 、Mg 2+ in the diatomite will react with the acid to form soluble salts and precipitate out, avoiding the impurities from falling off into the asphalt and causing the performance of the asphalt to decline, and exposing enough pore structures to increase the porosity of the diatomite.

[0026] Furthermore, during the above - mentioned A2 reaction process, the porous structure of the acid - treated diatomite has excellent adsorption performance. Adsorb the nitrogen - carbon precursor melamine and β - cyclodextrin on the acid - treated diatomite. After hydrothermal treatment and high - temperature calcination, the nitrogen - carbon precursor melamine and β - cyclodextrin self - assemble into layered - structured carbon nitride nanosheets on the acid - treated diatomite. And during the high - temperature calcination process, β - cyclodextrin decomposes by heat to generate gas, creating pores in the layered - structured carbon nitride nanosheets, realizing the synthesis of porous carbon nitride nanosheets on the acid - treated diatomite to obtain diatomite loaded with porous carbon nitride nanosheets.

[0027] Further, in the above A3 reaction process, the waste cooking oil is sieved and filtered to remove solid residues and some acidic compounds in the waste cooking oil, reducing the moisture sensitivity of the waste cooking oil; under the action of an alkaline sodium hydroxide solution, the triglycerides in the waste cooking oil are hydrolyzed to form glycerol and unsaturated fatty acids with small molecular chains, and the upper organic oil phase glycerol is removed to obtain pretreated waste cooking oil.

[0028] Further, in the above A4 reaction process, the mixed solution is composed of hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid. Using hydrogen peroxide as the oxygen supply body, glacial acetic acid as the oxygen carrier, and concentrated sulfuric acid as the catalyst, the double bonds on the molecular chain of the pretreated waste cooking oil are oxidized to epoxy bonds, realizing the epoxidation of the pretreated waste cooking oil to obtain epoxidized waste cooking oil.

[0029] Further, in the above A5 reaction process, hydrochloric acid is used as the catalyst, enabling the carboxyl groups contained in the epoxidized waste cooking oil to undergo an esterification reaction with the hydroxyl groups in polyethylene glycol, and the hydroxyl groups in polyethylene glycol can also react with the carboxyl groups in oxidized sugarcane bagasse fiber. In addition, the porous structure of the oxidized sugarcane bagasse fiber can adsorb the epoxidized waste cooking oil into the pores of the oxidized sugarcane bagasse fiber, causing the epoxidized waste cooking oil to be coated on the surface of the oxidized sugarcane bagasse fiber to obtain modified sugarcane bagasse fiber.

[0030] Further, in the above A6 reaction process, the oxygen-containing functional groups contained in the modified sugarcane bagasse fiber can be chemically bonded with the silicon hydroxyl groups generated by the hydrolysis of tetraethyl orthosilicate to form an aerogel with a cross-linked network structure, and the hydroxyl groups on the surface of the diatomite loaded with porous carbon nitride nanosheets can also react with the silicon hydroxyl groups generated by the hydrolysis of tetraethyl orthosilicate, causing the diatomite loaded with porous carbon nitride nanosheets to be embedded in the aerogel structure to obtain a reinforcing filler.

[0031] Further, in step A1, the dosage ratio of diatomite to nitric acid solution is (2 - 3) g : (45 - 55) mL.

[0032] Further, in step A2, the dosage ratio of melamine, β-cyclodextrin, deionized water, and acid-treated diatomite is (3 - 5) g : (0.1 - 0.2) g : (55 - 65) mL : (2 - 3) g.

[0033] Further, in step A3, the alkaline solution is sodium hydroxide solution with a mass fraction of 50 - 60%.

[0034] Further, in step A4, the mass ratio of the mixed solution to the pretreated waste cooking oil is (6 - 7) : (8 - 12).

[0035] Further, in step A5, the dosage ratio of epoxidized waste cooking oil, polyethylene glycol, p-toluenesulfonic acid, ethanol, and oxidized bagasse fiber is (5.2 - 5.4) g : (6.1 - 6.3) g : (0.3 - 0.4) g : (55 - 65) mL : (12 - 12.6) g.

[0036] Further, in step A6, the dosage ratio of deionized water, tetraethyl orthosilicate, ethanol, modified bagasse fiber, and diatomite loaded with porous carbon nitride nanosheets is (35 - 45) mL : (8 - 12) g : (75 - 85) mL : (5.2 - 5.4) g : (2.2 - 2.4) g.

[0037] Further, the particle size of the diatomite is 20 - 30 μm, and the pore diameter is 30 - 50 nm.

[0038] Further, the waste cooking oil is selected from one of rancid soybean oil, rancid rapeseed oil, rancid sunflower oil, rancid salad oil, and expired rapeseed oil.

[0039] Further, the waste cooking oil is rancid soybean oil, and the acid value is 75.1 - 75.8 mgKOH / g.

[0040] Further, the mixed solution is prepared by mixing hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid in a mass ratio of (3.4 - 3.6) : (2.3 - 2.6) : (0.02 - 0.04).

[0041] Further, the polyethylene glycol is polyethylene glycol 400.

[0042] The present invention has the following beneficial effects:

[0043] (1) In the technical solution of the present invention, the diatomite is treated with nitric acid, so that Al in the diatomite 3+ 、Fe 3+ 、Ca 2+ 、Mg 2+Impurities such as will react with the acid to form soluble salts and precipitate, avoiding the shedding of impurities into the asphalt, which may cause a decline in the performance of the asphalt. Moreover, there are sufficient pore structures in the exposed areas, increasing the porosity of the diatomite, which is beneficial to improving the compatibility with the new and old asphalt and enhancing the performance of the recycled asphalt concrete. Porous carbon nitride nanosheets are synthesized on the acid-treated diatomite. On the one hand, the porous carbon nitride nanosheets can enhance the absorption of visible light and improve the ultraviolet aging performance of the asphalt concrete. On the other hand, the porous carbon nitride nanosheets can adsorb and fix the metal impurities that have not been removed in the acid-treated diatomite, avoiding the shedding of impurities into the asphalt and affecting the performance of the asphalt. Moreover, the porous adsorption performance of the porous carbon nitride nanosheets and the acid-treated diatomite can adsorb the molten new and old asphalt mixtures on the surface, improving the dispersibility of the diatomite loaded with porous carbon nitride nanosheets in the asphalt mixture, avoiding poor compatibility between the new and old asphalt, which may lead to the phenomenon that the recycled asphalt concrete pavement becomes potholed soon after use, and improving the rutting resistance of the asphalt concrete. In addition, the layered porous carbon nitride nanosheets and the acid-treated diatomite can effectively prevent the transfer of heat to the asphalt pavement, improving the aging performance of the recycled asphalt concrete.

[0044] (2) In the technical solution of the present invention, the waste cooking oil is screened and filtered to remove solid residues and some acidic compounds in the waste cooking oil, reducing the moisture sensitivity of the waste cooking oil. Under the action of the alkaline sodium hydroxide solution, the triglycerides in the waste cooking oil are hydrolyzed to form glycerol and unsaturated fatty acids with small molecular chains. Their long-chain alkane structure interacts with the asphalt, enabling the waste cooking oil to penetrate into the asphalt better and improving the crack resistance of the asphalt. Epoxidation treatment of the waste cooking oil can consume the easily oxidized double bonds in the waste cooking oil, avoiding the easy aging of the asphalt caused by the addition of the waste cooking oil to the asphalt matrix. Moreover, the carried epoxy groups can improve the bonding strength between the waste cooking oil and the asphalt, enabling the waste cooking oil components to fill into the asphalt concrete, improving the high-temperature resistance and anti-aging performance of the asphalt concrete, and turning the waste cooking oil into a useful material, which is cheap and easily available.

[0045] (3) In the technical solution of the present invention, the epoxidized waste cooking oil is coated on the surface of oxidized bagasse fibers by polyethylene glycol oil. On the one hand, polyethylene glycol consumes the carboxyl groups in the epoxidized waste cooking oil, reducing the acidity of the waste cooking oil. Adding it to asphalt is beneficial to increasing the viscosity of asphalt and enhancing the anti-aging performance of asphalt concrete. Moreover, polyethylene glycol forms a cross-linked network structure in the epoxidized waste cooking oil and fills into the asphalt concrete, significantly improving the mechanical strength of the asphalt concrete. On the other hand, bagasse fibers can fill into the pore structure of the asphalt concrete and have an excellent aspect ratio, improving the toughness of the asphalt concrete and reducing cracks caused by temperature changes, thereby extending the service life of the road surface. In addition, the epoxidized waste cooking oil is coated on the surface of oxidized bagasse fibers. The long-chain alkane structure in the epoxidized waste cooking oil interacts with new and old asphalt, improving the compatibility of the oxidized bagasse fibers in the asphalt and enhancing the compressive strength of the asphalt concrete.

[0046] (4) In the technical solution of the present invention, the oxidized bagasse fibers loaded with waste cooking oil, the diatomite loaded with porous carbon nitride nanosheets and tetraethyl orthosilicate are mixed and reacted to form an aerogel structure with a cross-linked network structure. On the one hand, the oxidized bagasse fibers loaded with waste cooking oil serve as the aerogel skeleton structure. The long-chain alkane structure contained in the waste cooking oil on the surface interacts with new and old asphalt, enabling the aerogel to fill into the asphalt. Moreover, the formed aerogel has a porous structure and can adsorb molten new and old asphalt, improving the compatibility of new and old asphalt and avoiding the phenomenon that the regenerated asphalt concrete road surface becomes potholed soon due to poor compatibility of new and old asphalt. On the other hand, the aerogel structure with a cross-linked network structure has high mechanical properties. Incorporating it into the asphalt concrete can effectively improve the flexibility and crack resistance of the asphalt concrete. Specific embodiments

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0048] The raw materials used in the embodiments of the present invention are as follows, and all the reagents used are of analytical grade.

[0049] The thermosetting resin is polycarbonate.

[0050] The particle size of the diatomite is 25 μm and the pore diameter is 40 nm.

[0051] The waste cooking oil is rancid soybean oil with an acid value of 75.5 mg KOH / g.

[0052] The polyethylene glycol is polyethylene glycol 400, Green Link (Jining) Chemical Technology Co., Ltd.

[0053] The new asphalt is 70# base asphalt.

[0054] The particle size of the recycled asphalt mixture is 3.8 mm.

[0055] The apparent density of basalt is 2.9 g / cm 3 , the water absorption rate is 1.55%, the crushing value is 15.2%, and the particle size is 9 mm.

[0056] The crushing value index of limestone is grade II, the compressive strength is 90 MPa, and the particle size is 2 mm.

[0057] The mineral powder is S95 grade mineral powder, and the apparent density is 2.65 g / cm 3 , the specific surface area is 475 m 2 / kg, the water content is 0.5%, and the particle size is 4 mm.

[0058] The length of the bagasse fiber is 0.3 μm and the diameter is 70 nm.

[0059] The oxidized bagasse fiber is specifically prepared by the following steps:

[0060] Add 1.2 g of bagasse fiber to 100 mL of deionized water, stir evenly, add 0.016 g of 2,2,6,6-tetramethylpiperidine-1-oxyl radical, 0.1 g of sodium bromide, and 2 g of sodium hypochlorite, stir evenly, add 2.5 mL of hydrochloric acid with a mass fraction of 36% to adjust the pH to 10, react at room temperature and a rate of 500 r / min for 30 min, then filter, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 min to obtain oxidized bagasse fiber.

[0061] The reinforcing filler in Example 1 is specifically prepared by the following steps:

[0062] A1. Add 2.5 g of diatomite to 50 mL of nitric acid solution with a concentration of 4 mol / L, stir evenly, stir and treat at 80 °C for 4.5 h, cool to room temperature, filter, wash with deionized water until the washing liquid is neutral, and dry in an oven at 105 °C for 4 h to obtain acid-treated diatomite;

[0063] A2. Add 4 g of melamine and 0.15 g of β-cyclodextrin to 60 mL of deionized water, stir at 550 r / min for 35 min, add 2.5 g of acid-treated diatomite, stir evenly, place it in a hydrothermal reactor, stir and react at 180 °C for 22 h. After cooling to room temperature, filter it, wash it 3 times with deionized water, dry it in an oven at 60 °C for 10 min, place it in a muffle furnace, calcine it at 550 °C for 2.5 h, cool to room temperature, take it out, and obtain diatomite loaded with porous carbon nitride nanosheets;

[0064] A3. Screen 15 g of rancid soybean oil through a 400-mesh sieve to remove large particles, preheat it to 100 °C, add an alkaline solution of 50% mass fraction of sodium hydroxide solution to adjust the pH to 8.5, place it in a water bath at 100 °C, stir for 20 min, let it stand, and remove the upper organic oil phase glycerol to obtain pretreated waste cooking oil;

[0065] A4. Mix 6.5 g of the mixed solution and 10 g of pretreated waste cooking oil, place it in an oil bath, heat it to 50 °C, stir at a rate of 100 r / min for 4 h, continue to heat it to 123 °C, remove the moisture, and cool to room temperature to obtain epoxidized waste cooking oil; The mixed solution is composed of hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid mixed in a mass ratio of 3.5:2.5:0.03;

[0066] A5. Mix 5.3 g of epoxidized waste cooking oil and 6.2 g of polyethylene glycol, stir evenly, add 0.35 g of p-toluenesulfonic acid, stir and react at 90 °C for 1.5 h, cool to 70 - 80 °C, add 60 mL of ethanol and 12.3 g of oxidized bagasse fiber and mix, stir and react for 9 h, then stir at 95 °C until the organic solvent ethanol volatilizes, and cool to room temperature to obtain modified bagasse fiber;

[0067] A6. Mix 40 mL of deionized water, 10 g of tetraethyl orthosilicate, and 80 mL of ethanol, stir evenly, add hydrochloric acid with a concentration of 1 mol / L to adjust the pH to 2.5, stir for 30 min, add 5.3 g of modified bagasse fiber, 2.3 g of diatomite loaded with porous carbon nitride nanosheets, and ammonia water with a concentration of 1 mol / L to adjust the pH to 7, let it stand to form a gel. After the gel is aged for 24 h, place it in a freezer and dry it at -25 °C for 20 h to obtain the reinforcing filler.

[0068] Comparative Example 1 The difference between this comparative example and Example 1 is that the acid-treated diatomite is replaced by diatomite, and the rest of the steps and raw materials are the same as those in Example 1.

[0069] The reinforcing filler is specifically prepared by the following steps:

[0070] A1. Add 4 g of melamine and 0.15 g of β-cyclodextrin to 60 mL of deionized water, stir at 550 r / min for 35 min, add 2.5 g of diatomite, stir evenly, place in a hydrothermal autoclave, stir and react at 180 °C for 22 h. After cooling to room temperature, filter, wash with deionized water 3 times, dry in an oven at 60 °C for 10 min, place in a muffle furnace, calcine at 550 °C for 2.5 h, cool to room temperature, take out, and obtain diatomite loaded with porous carbon nitride nanosheets;

[0071] A2. Screen 15 g of rancid soybean oil through a 400-mesh sieve to remove large particles, preheat to 100 °C, add an alkaline solution of 50% mass fraction of sodium hydroxide solution to adjust the pH to 8.5, place in a water bath at 100 °C, stir for 20 min, let stand, and remove the upper organic oil phase glycerol to obtain pretreated waste cooking oil;

[0072] A3. Mix 6.5 g of the mixed solution and 10 g of pretreated waste cooking oil, place in an oil bath, heat up to 50 °C, stir at a rate of 100 r / min for 4 h, continue to heat up to 123 °C, remove moisture, and cool to room temperature to obtain epoxidized waste cooking oil; the mixed solution is composed of hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid mixed in a mass ratio of 3.5:2.5:0.03;

[0073] A4. Mix 5.3 g of epoxidized waste cooking oil and 6.2 g of polyethylene glycol, stir evenly, add 0.35 g of p-toluenesulfonic acid, stir and react at 90 °C for 1.5 h, cool down to 70 - 80 °C, add 60 mL of ethanol and 12.3 g of oxidized sugarcane fiber, stir and react for 9 h, then stir at 95 °C until the organic solvent ethanol volatilizes, cool to room temperature, and obtain modified sugarcane fiber;

[0074] A5. Mix 40 mL of deionized water, 10 g of tetraethyl orthosilicate, and 80 mL of ethanol, stir evenly, add hydrochloric acid with a concentration of 1 mol / L to adjust the pH to 2.5, stir for 30 min, add 5.3 g of modified sugarcane fiber, 2.3 g of diatomite loaded with porous carbon nitride nanosheets, and ammonia water with a concentration of 1 mol / L to adjust the pH to 7, let stand to form a gel. After the gel is aged for 24 h, place it in a freezer and dry at -25 °C for 20 h to obtain the reinforcing filler.

[0075] Comparative Example 2 The difference between this comparative example and Example 1 is that the diatomite loaded with porous carbon nitride nanosheets is replaced with acid-treated diatomite, and the remaining steps and raw materials are the same as those in Example 1.

[0076] The reinforcing filler is specifically prepared by the following steps:

[0077] A1. Add 2.5 g of diatomaceous earth to 50 mL of a nitric acid solution with a concentration of 4 mol / L, stir evenly, stir and process at 80 °C for 4.5 h, cool to room temperature, filter, wash with deionized water until the washing liquid is neutral, and dry in an oven at 105 °C for 4 h to obtain acid-treated diatomaceous earth;

[0078] A2. Screen 15 g of rancid soybean oil through a 400-mesh sieve to remove large particles, preheat to 100 °C, add an alkaline solution of a 50% by mass potassium hydroxide solution to adjust the pH to 8.5, place in a water bath at 100 °C, stir for 20 min, let stand, and remove the upper organic oil phase glycerol to obtain pretreated waste cooking oil;

[0079] A3. Mix 6.5 g of the mixed solution and 10 g of pretreated waste cooking oil, place in an oil bath, heat to 50 °C, stir at a rate of 100 r / min for 4 h, continue to heat to 123 °C, remove water, and cool to room temperature to obtain epoxidized waste cooking oil; the mixed solution is composed of hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid mixed in a mass ratio of 3.5:2.5:0.03;

[0080] A4. Mix 5.3 g of epoxidized waste cooking oil and 6.2 g of polyethylene glycol, stir evenly, add 0.35 g of p-toluenesulfonic acid, stir and react at 90 °C for 1.5 h, cool to 70 - 80 °C, add 60 mL of ethanol and 12.3 g of oxidized bagasse fiber and mix, stir and react for 9 h, then stir at 95 °C until the organic solvent ethanol volatilizes, and cool to room temperature to obtain modified bagasse fiber;

[0081] A5. Mix 40 mL of deionized water, 10 g of tetraethyl orthosilicate, and 80 mL of ethanol, stir evenly, add hydrochloric acid with a concentration of 1 mol / L to adjust the pH to 2.5, stir for 30 min, add 5.3 g of modified bagasse fiber, 2.3 g of acid-treated diatomaceous earth, and ammonia water with a concentration of 1 mol / L to adjust the pH to 7, let stand to form a gel, after the gel is aged for 24 h, place it in a freezer and dry at -25 °C for 20 h to obtain the reinforcing filler.

[0082] Comparative Example 3 The difference between this comparative example and Example 1 is that the epoxidized waste cooking oil is replaced with pretreated waste cooking oil, and the remaining steps and raw materials are the same as in Example 1.

[0083] The reinforcing filler is specifically prepared by the following steps:

[0084] A1. Add 2.5 g of diatomaceous earth to 50 mL of a nitric acid solution with a concentration of 4 mol / L, stir evenly, stir and process at 80 °C for 4.5 h, cool to room temperature, filter, wash with deionized water until the washing liquid is neutral, and dry in an oven at 105 °C for 4 h to obtain acid-treated diatomaceous earth;

[0085] A2. Add 4 g of melamine and 0.15 g of β-cyclodextrin to 60 mL of deionized water, stir at 550 r / min for 35 min, add 2.5 g of acid-treated diatomite, stir evenly, place in a hydrothermal reactor, stir and react at 180 °C for 22 h. After cooling to room temperature, filter, wash with deionized water 3 times, dry in an oven at 60 °C for 10 min, place in a muffle furnace, calcine at 240 °C for 2.5 h, cool to room temperature, take out, and obtain diatomite loaded with porous carbon nitride nanosheets;

[0086] A3. Screen 15 g of rancid soybean oil through a 400-mesh sieve to remove large particles, preheat to 100 °C, add an alkaline solution of 50% by mass of sodium hydroxide solution to adjust the pH to 8.5, place in a water bath at 100 °C, stir for 20 min, let stand, and remove the upper organic oil phase glycerol to obtain pretreated waste cooking oil;

[0087] A4. Mix 5.3 g of pretreated waste cooking oil and 6.2 g of polyethylene glycol, stir evenly, add 0.35 g of p-toluenesulfonic acid, stir and react at 90 °C for 1.5 h, cool to 70 - 80 °C, add 60 mL of ethanol and 12.3 g of oxidized sugarcane fiber, stir and react for 9 h, then stir at 95 °C until the organic solvent ethanol volatilizes, and cool to room temperature to obtain modified sugarcane fiber;

[0088] A5. Mix 40 mL of deionized water, 10 g of tetraethyl orthosilicate and 80 mL of ethanol, stir evenly, add hydrochloric acid with a concentration of 1 mol / L to adjust the pH to 2.5, stir for 30 min, add 5.3 g of modified sugarcane fiber, 2.3 g of diatomite loaded with porous carbon nitride nanosheets and ammonia water with a concentration of 1 mol / L to adjust the pH to 7, let stand to form a gel. After the gel is aged for 24 h, place it in a freezer and dry at -25 °C for 20 h to obtain the reinforcing filler.

[0089] Comparative Example 4 The difference between this comparative example and Example 1 is that polyethylene glycol was not added, and the remaining steps and raw materials are the same as those in Example 1.

[0090] The reinforcing filler is specifically prepared by the following steps:

[0091] A1. Add 2.5 g of diatomite to 50 mL of nitric acid solution with a concentration of 4 mol / L, stir evenly, stir and treat at 80 °C for 4.5 h, cool to room temperature, filter, wash with deionized water until the washing liquid is neutral, and dry in an oven at 105 °C for 4 h to obtain acid-treated diatomite;

[0092] A2. Add 4 g of melamine and 0.15 g of β-cyclodextrin to 60 mL of deionized water, stir at 550 r / min for 35 min, add 2.5 g of acid-treated diatomite, stir evenly, place it in a hydrothermal reactor, stir and react at 180 °C for 22 h. After cooling to room temperature, filter, wash with deionized water 3 times, dry in an oven at 60 °C for 10 min, place it in a muffle furnace, calcine at 550 °C for 2.5 h, cool to room temperature, take out, and obtain diatomite loaded with porous carbon nitride nanosheets;

[0093] A3. Screen 15 g of rancid soybean oil through a 400-mesh sieve to remove large particles, preheat to 100 °C, add an alkaline solution of 50% mass fraction of sodium hydroxide solution to adjust the pH to 8.5, place it in a water bath at 100 °C, stir for 20 min, let it stand, and remove the upper organic oil phase glycerol to obtain pretreated waste cooking oil;

[0094] A4. Mix 6.5 g of the mixed solution and 10 g of pretreated waste cooking oil, place it in an oil bath, heat up to 50 °C, stir at a rate of 100 r / min for 4 h, continue to heat up to 123 °C, remove the water, and cool to room temperature to obtain epoxidized waste cooking oil; the mixed solution is composed of hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid mixed in a mass ratio of 3.5:2.5:0.03;

[0095] A5. Mix 5.3 g of epoxidized waste cooking oil and 12.3 g of oxidized sugarcane fiber to obtain a composite;

[0096] A6. Mix 40 mL of deionized water, 10 g of tetraethyl orthosilicate, and 80 mL of ethanol, stir evenly, add hydrochloric acid with a concentration of 1 mol / L to adjust the pH to 2.5, stir for 30 min, add 5.3 g of the composite, 2.3 g of diatomite loaded with porous carbon nitride nanosheets, and ammonia water with a concentration of 1 mol / L to adjust the pH to 7, let it stand to form a gel. After the gel is aged for 24 h, place it in a freezer and dry at -25 °C for 20 h to obtain the reinforcing filler.

[0097] Comparative Example 5 The difference between this comparative example and Example 1 is that tetraethyl orthosilicate was not added, and the remaining steps and raw materials are the same as those in Example 1.

[0098] The reinforcing filler is specifically prepared by the following steps:

[0099] A1. Add 2.5 g of diatomite to 50 mL of a nitric acid solution with a concentration of 4 mol / L, stir evenly, stir and treat at 80 °C for 4.5 h, cool to room temperature, filter, wash with deionized water until the washing liquid is neutral, and dry in an oven at 105 °C for 4 h to obtain acid-treated diatomite;

[0100] A2. Add 4 g of melamine and 0.15 g of β-cyclodextrin to 60 mL of deionized water, stir at 550 r / min for 35 min, add 2.5 g of acid-treated diatomite, stir evenly, place it in a hydrothermal reactor, stir and react at 180 °C for 22 h. After cooling to room temperature, filter it, wash it 3 times with deionized water, dry it in an oven at 60 °C for 10 min, place it in a muffle furnace, calcine it at 550 °C for 2.5 h, cool to room temperature, take it out, and obtain diatomite loaded with porous carbon nitride nanosheets;

[0101] A3. Screen 15 g of rancid soybean oil through a 400-mesh sieve to remove large particles, preheat it to 100 °C, add an alkaline solution of 50% mass fraction of sodium hydroxide solution to adjust the pH to 8.5, place it in a water bath at 100 °C, stir for 20 min, let it stand, and remove the upper organic oil phase glycerol to obtain pretreated waste cooking oil;

[0102] A4. Mix 6.5 g of the mixed solution and 10 g of pretreated waste cooking oil, place it in an oil bath, heat it to 50 °C, stir at a rate of 100 r / min for 4 h, continue to heat it to 123 °C, remove the moisture, and cool to room temperature to obtain epoxidized waste cooking oil; the mixed solution is composed of hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid mixed in a mass ratio of 3.5:2.5:0.03;

[0103] A5. Mix 5.3 g of epoxidized waste cooking oil and 6.2 g of polyethylene glycol, stir evenly, add 0.35 g of p-toluenesulfonic acid, stir and react at 90 °C for 1.5 h, cool down to 70 - 80 °C, add 60 mL of ethanol and 12.3 g of oxidized sugarcane bagasse fiber and mix, stir and react for 9 h, then stir at 95 °C until the organic solvent ethanol volatilizes, and cool to room temperature to obtain modified sugarcane bagasse fiber;

[0104] A6. Mix 5.3 g of modified sugarcane bagasse fiber and 2.3 g of diatomite loaded with porous carbon nitride nanosheets to obtain enhanced filler.

[0105] Example 2 A recycled asphalt concrete, comprising the following raw materials in parts by mass: 70 parts of 70# base asphalt, 10 parts of limestone, 5 parts of basalt, 3 parts of mineral powder, 40 parts of recycled asphalt mixture, 1 part of the enhanced filler prepared in Example 1, and 3 parts of polycarbonate;

[0106] A preparation method of recycled asphalt concrete, comprising the following preparation steps:

[0107] S1. Place 70# base asphalt in a mixing pot, heat it to 95 °C while stirring to obtain preheated asphalt, mix limestone, basalt, and mineral powder, stir at 160 °C for 5 min, add the preheated asphalt, and continue to stir for 5 min to obtain a mixture;

[0108] S2. Mix the recycled asphalt mixture with the reinforcing filler prepared in Example 1, stir at 130 °C for 5 min, add the mixture and polycarbonate, and stir at 100 °C for 3 min to obtain recycled asphalt concrete.

[0109] Example 3 A recycled asphalt concrete, comprising the following raw materials in parts by mass: 75 parts of 70# base asphalt, 13 parts of limestone, 8 parts of basalt, 5 parts of mineral powder, 50 parts of recycled asphalt mixture, 3 parts of the reinforcing filler prepared in Example 1, 5 parts of polycarbonate;

[0110] A preparation method of recycled asphalt concrete, comprising the following preparation steps:

[0111] S1. Place the 70# base asphalt in a mixing pot, heat it to 100 °C while stirring to obtain preheated asphalt, mix the limestone, basalt, and mineral powder, stir at 170 °C for 8 min, add the preheated asphalt, and continue to stir for 8 min to obtain a mixture;

[0112] S2. Mix the recycled asphalt mixture with the reinforcing filler prepared in Example 1, stir at 140 °C for 8 min, add the mixture and polycarbonate, and stir at 105 °C for 4 min to obtain recycled asphalt concrete.

[0113] Example 4 A recycled asphalt concrete, comprising the following raw materials in parts by mass: 80 parts of 70# base asphalt, 15 parts of limestone, 10 parts of basalt, 8 parts of mineral powder, 60 parts of recycled asphalt mixture, 5 parts of the reinforcing filler prepared in Example 1, 6 parts of polycarbonate;

[0114] A preparation method of recycled asphalt concrete, comprising the following preparation steps:

[0115] S1. Place the 70# base asphalt in a mixing pot, heat it to 105 °C while stirring to obtain preheated asphalt, mix the limestone, basalt, and mineral powder, stir at 180 °C for 10 min, add the preheated asphalt, and continue to stir for 10 min to obtain a mixture;

[0116] S2. Mix the recycled asphalt mixture with the reinforcing filler prepared in Example 1, stir at 150 °C for 10 min, add the mixture and polycarbonate, and stir at 110 °C for 5 min to obtain recycled asphalt concrete.

[0117] Comparative Example 6 The difference between this comparative example and Example 3 is that the reinforcing filler prepared in Example 1 is replaced with the substance prepared in Comparative Example 1, and the remaining steps are the same as those in Example 3.

[0118] Comparative Example 7 The difference between this comparative example and Example 3 is that the reinforcing filler prepared in Example 1 is replaced with the substance prepared in Comparative Example 2, and the remaining steps are the same as those in Example 3.

[0119] Comparative Example 8 The difference between this comparative example and Example 3 is that the reinforcing filler prepared in Example 1 is replaced with the substance prepared in Comparative Example 3, and the remaining steps are the same as those in Example 3.

[0120] Comparative Example 9 The difference between this comparative example and Example 3 is that the reinforcing filler prepared in Example 1 is replaced with the substance prepared in Comparative Example 4, and the remaining steps are the same as those in Example 3.

[0121] Comparative Example 10 The difference between this comparative example and Example 3 is that the reinforcing filler prepared in Example 1 is replaced with the substance prepared in Comparative Example 5, and the remaining steps are the same as those in Example 3.

[0122] Now, the performance of the recycled asphalt concrete prepared in Examples 2 - 4 and Comparative Examples 6 - 10 is tested.

[0123] The high - temperature rutting test, low - temperature beam bending test, and immersion Marshall test are carried out according to the methods of T0719 - 2011, T0715 - 2011, and T0709 - 2011 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20 - 2011) respectively to measure the rutting resistance (dynamic stability), compressive strength, and stability of the above - prepared asphalt pavement materials.

[0124] Aging resistance performance test: The asphalt pavement materials are placed in an aging test chamber. The aging lamp is a 420W high - pressure mercury lamp with an aluminum reflector lamp cover. The irradiation time of the high - pressure mercury lamp is 72h, and the softening point (°C) and ductility (mm) of the asphalt pavement materials are recorded.

[0125] The measured data are shown in Table 1 below:

[0126] Table 1

[0127]

[0128] In Comparative Example 6, the acid - treated diatomite is replaced with the reinforcing filler prepared from diatomite and added to the recycled asphalt concrete, and its anti - aging performance and mechanical properties decline. This proves that after the diatomite is treated with nitric acid, the Al 3+ , Fe 3+ , Ca 2+ , Mg 2+ and other impurities in the diatomite will react with the acid to form soluble salts and precipitate out, avoiding the impurities from falling off into the asphalt and causing the decline of asphalt performance. Moreover, the porous structure of the acid - treated diatomite is conducive to the synthesis of a large number of porous carbon nitride nanosheets on the acid - treated diatomite, improving the rutting resistance and anti - aging performance of the asphalt concrete. While in Comparative Example 6, the diatomite is not acid - treated, and its anti - aging performance and mechanical properties decline.

[0129] In Comparative Example 7, the diatomite loaded with porous carbon nitride nanosheets was replaced with an enhanced filler prepared from acid-treated diatomite and added to the recycled asphalt concrete. Its anti-aging performance and mechanical properties decreased, which proved that synthesizing porous carbon nitride nanosheets on acid-treated diatomite could enhance the absorption of visible light, improve the anti-aging performance of asphalt concrete, and the porous carbon nitride nanosheets could adsorb and fix the metal impurities not removed in the acid-treated diatomite, avoiding the impurities falling off into the asphalt and affecting the service performance of the asphalt. In Comparative Example 7, the porous carbon nitride nanosheets were absent, and its anti-aging performance and mechanical properties decreased.

[0130] In Comparative Example 8, the epoxidized waste cooking oil was replaced with an enhanced filler prepared from pretreated waste cooking oil and added to the recycled asphalt concrete. Its anti-aging performance and mechanical properties decreased, which proved that epoxidizing the waste cooking oil could consume the easily oxidized double bonds in the waste cooking oil, avoid the asphalt being easily aged due to the addition of the waste cooking oil into the asphalt matrix, and the carried epoxy groups could improve the bonding strength between the waste cooking oil and the asphalt, enabling the waste cooking oil and oxidized sugarcane fiber to be filled into the asphalt concrete, improving the anti-aging performance and mechanical strength of the asphalt concrete. In Comparative Example 8, the pretreated waste cooking oil contained easily oxidized double bonds, and its anti-aging performance and mechanical properties decreased.

[0131] In Comparative Example 9, the enhanced filler prepared without adding polyethylene glycol was added to the recycled asphalt concrete. Its mechanical strength and aging resistance decreased, which proved that polyethylene glycol consumed the carboxyl groups in the epoxidized waste cooking oil, reduced the acidity of the waste cooking oil, and adding it to the asphalt was beneficial to increasing the viscosity of the asphalt, strengthening the asphalt. Moreover, polyethylene glycol formed a cross-linked network structure in the epoxidized waste cooking oil and filled into the asphalt concrete, significantly improving the mechanical strength of the asphalt concrete. In Comparative Example 9, polyethylene glycol was absent, and its mechanical strength and aging resistance decreased.

[0132] In Comparative Example 10, the enhanced filler prepared without adding tetraethyl orthosilicate was added to the recycled asphalt concrete. Its mechanical properties decreased, which proved that the oxidized sugarcane fiber loaded with waste cooking oil, the diatomite loaded with porous carbon nitride nanosheets, and tetraethyl orthosilicate reacted and mixed to form an aerogel structure with a cross-linked network structure, improving the compatibility between the new and old asphalt, and the aerogel structure with a cross-linked network structure had high mechanical properties. In Comparative Example 10, the aerogel structure prepared without tetraethyl orthosilicate was absent, and its mechanical properties decreased.

[0133] The data in Table 1 show that the recycled asphalt concrete prepared in Examples 2-4 met the requirements of the test performance, while the recycled asphalt concrete prepared in Comparative Examples 6-10 did not meet the performance requirements standard, indicating that the recycled asphalt concrete prepared by the present invention has excellent aging resistance and mechanical strength.

[0134] In the description of the specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0135] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar ways to substitute, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A recycled asphalt concrete, characterized in that, It includes the following raw materials in parts by mass: 70 - 80 parts of new asphalt, 10 - 15 parts of limestone, 5 - 10 parts of basalt, 3 - 8 parts of mineral powder, 40 - 60 parts of recycled asphalt mixture, 1 - 5 parts of reinforcing filler, and 3 - 6 parts of thermosetting resin; The reinforcing filler is obtained by mixing and reacting epoxidized waste cooking oil, polyethylene glycol, and oxidized bagasse fibers, and then mixing with diatomite loaded with porous carbon nitride nanosheets and tetraethyl orthosilicate; The epoxidized waste cooking oil is obtained by screening and filtering waste cooking oil, treating it with an alkaline solution, and then mixing it with a mixed solution; The diatomite loaded with porous carbon nitride nanosheets is obtained by treating diatomite with an acid, mixing it with melamine and β - cyclodextrin, and then calcining it at a high temperature; 2. A recycled asphalt concrete according to claim 1, wherein, The waste cooking oil is selected from one of rancid soybean oil, rancid rapeseed oil, rancid sunflower oil, rancid salad oil, and expired rapeseed oil; 3. A recycled asphalt concrete according to claim 1, characterized in that, The alkaline solution is a sodium hydroxide solution with a mass fraction of 50 - 60%; 4. A recycled asphalt concrete according to claim 1, wherein, The mixed solution is composed of hydrogen peroxide, glacial acetic acid, and concentrated sulfuric acid mixed in a mass ratio of (3.4 - 3.6):(2.3 - 2.6):(0.02 - 0.04); 5. A recycled asphalt concrete according to claim 1, wherein, The particle size of the diatomite is 20 - 30μm, and the pore size is 30 - 50nm; 6. A recycled asphalt concrete according to claim 1, characterized in that, The new asphalt is 70# base asphalt; the particle size of the recycled asphalt mixture is 3.2 - 4.3mm; 7. A recycled asphalt concrete according to claim 1, characterized in that, The apparent density of the basalt is 2.7 - 3.1 g / cm 3 , the water absorption rate is 1.5 - 1.6%, the crushing value is 15.2 - 17.3%, and the particle size is 8 - 10 mm.

8. A recycled asphalt concrete according to claim 1, wherein, The crushing value index of the limestone is grade two, the compressive strength is 80 - 100MPa, and the particle size is 1 - 3mm; 9. A recycled asphalt concrete according to claim 1, wherein, The mineral powder is S95 grade mineral powder with an apparent density of 2.6 - 2.7 g / cm 3 , a specific surface area of 450 - 500 m 2 / kg, a water content of 0.2 - 1%, and a particle size of 3.2 - 4.3 mm.

10. A method for preparing the recycled asphalt concrete according to any one of claims 1 to 9, characterized in that, It includes the following steps: S1. Place the new asphalt in a mixing pot, heat it to 95 - 105°C while stirring to obtain preheated asphalt. Mix the limestone, basalt, and mineral powder, stir at 160 - 180°C for 5 - 10 minutes, add the preheated asphalt, and continue to stir for 5 - 10 minutes to obtain a mixture; S2. Mix the recycled asphalt mixture and the reinforcing filler, stir at 130 - 150°C for 5 - 10 minutes, add the mixture and the thermosetting resin, and stir at 100 - 110°C for 3 - 5 minutes to obtain recycled asphalt concrete.

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