Modified filler, SMA-13 asphalt mixture and preparation method of SMA-13 asphalt mixture

Abstract

The invention discloses a modified filler, an SMA-13 asphalt mixture and a preparation method thereof, and relates to the technical field of asphalt, the SMA-13 asphalt mixture is prepared from the following components: 4-8 parts of SMA-13 asphalt, 4-8 parts of modified filler, 50-80 parts of coarse aggregate, and 20-50 parts of fine aggregate; the modified filler is prepared from the following components: 10 parts of ardealite, 5-8 parts of quick lime, 5-60 parts of limestone and 10-30 parts of modified basalt fiber; the prepared asphalt mixture has excellent high-temperature stability, low-temperature crack resistance, water damage resistance and anti-fatigue durability, the service life of a road is prolonged, the maintenance cost is reduced, and a safe, economical, environment-friendly and efficient novel material system is provided for the road construction industry.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt, and particularly relates to a modified filler, an SMA-13 asphalt mixture and a preparation method thereof. Background Art

[0002] An asphalt mixture is a composite material formed by mixing asphalt and aggregates in a certain proportion, and is the main structural material for highways, airports, urban roads and square pavements. According to the grading characteristics and functional requirements, asphalt mixtures can be divided into various types such as dense-graded, open-graded, asphalt macadam, penetration macadam and porous asphalt mixtures. Among them, SMA (Stone Matrix Asphalt) mixture is a framework dense-graded asphalt mixture, which consists of a coarse aggregate framework, asphalt mastic (a mixture of asphalt and filler) and a fiber stabilizer, and has the characteristics of "more coarse and less fine, discontinuous grading". SMA mixtures are widely used in high-grade highways and heavy-duty traffic pavements due to their good high-temperature stability, rutting resistance, skid resistance, wear resistance and anti-aging ability.

[0003] Phosphogypsum is the main solid waste generated in the production process of wet-process phosphoric acid, and its main component is calcium sulfate dihydrate (CaSO4·2H2O). China produces about 70 million tons of phosphogypsum every year, which occupies a large amount of land resources for stacking, and there are environmental risks such as acid leaching and heavy metal pollution. The resource utilization of phosphogypsum is an effective way to solve its environmental problems, and the current main application directions include cement retarders, building gypsum, ammonium sulfate production and subgrade fillers. However, due to impurities such as residual free acid, soluble phosphorus and fluorine in phosphogypsum, its direct application is severely restricted. Especially when used as a filler in road engineering, its acidic characteristics will affect the water stability and durability of asphalt mixtures.

[0004] CN108147771A discloses an asphalt concrete, which comprises the following raw materials in parts by weight: 47 parts of matrix asphalt, 3 parts of stabilizer, 2 parts of modifier, 7 parts of ultraviolet barrier particles, and 39 parts of concrete; the stabilizer is sulfur, the modifier is YH791H linear SBS, and the concrete is a mixture of sodium sulfite powder, reinforcing fiber, fly ash, iron powder, phosphogypsum and aggregate.

[0005] However, with the continuous increase of traffic loads and the increasing complexity of climate conditions, the existing asphalt mixture technology faces many challenges: First, the rutting deformation problem of the road surface under high-temperature conditions is still prominent, especially in areas with heavy traffic and extremely high-temperature climates; Second, the brittleness of asphalt mixtures increases under low-temperature environments, and temperature stress cracking and fatigue cracks are prone to occur; Third, water damage, as the main factor affecting the durability of asphalt pavements, leads to the peeling of the asphalt-aggregate interface and a reduction in strength; Fourth, asphalt mixtures are affected by multiple factors such as ultraviolet radiation, oxygen oxidation, and moisture erosion during service, accelerating aging and resulting in performance degradation; Fifth, the existing modification technologies generally have problems such as high cost, complex processes, and poor environmental friendliness, and it is difficult to achieve the coordinated improvement of multiple performances. In addition, although the resource utilization of industrial by-products is beneficial to saving resources and protecting the environment, how to solve the problems of stability and compatibility during their application is still a technical challenge.

[0006] Therefore, developing a multifunctional synergistic modification filler system to solve the comprehensive performance problems of asphalt mixtures in complex environments and simultaneously achieve the resource utilization of industrial by-products has important theoretical research value and engineering application prospects. Summary of the Invention

[0007] In order to solve the deficiencies of the existing technology, the purpose of the present invention is to provide a modified filler, SMA-13 asphalt mixture and its preparation method. The SMA-13 asphalt mixture realizes a significant improvement in the comprehensive performance of pavement materials through a multi-functional synergistic mechanism, can effectively solve the technical problems of poor service performance of traditional asphalt mixtures under extreme climate and heavy traffic conditions, and also realizes the resource utilization of industrial by-products, with significant economic and environmental benefits.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A modified filler, in parts by weight, is made of the following components: 10 parts of phosphogypsum, 5-8 parts of quicklime, 5-60 parts of limestone, and 10-30 parts of modified basalt fiber.

[0010] The phosphogypsum has a particle size of 150-500 mesh and a pH value of 3.5-4.1; the quicklime has a particle size of 150-500 mesh, and the limestone has a particle size ≤ 0.6 mm.

[0011] Preferably, the preparation method of the modified basalt fiber includes the following steps:

[0012] (1) Clean the basalt fiber, then immerse it in an ethanol aqueous solution, add 3-piperazinylpropylmethyldimethoxysilane, adjust the pH of the system, stir and react, filter, wash, and dry the product to obtain pretreated fiber;

[0013] Surface treatment with silane coupling agent: 3-Piperazinylpropylmethyldimethoxysilane first undergoes a hydrolysis reaction in an acidic ethanol aqueous solution. The methoxy group (–OCH3) reacts with water molecules to form silanol groups (–Si–OH) and methanol. Subsequently, the hydrolyzed silane undergoes a condensation reaction with the siloxyl groups (Si–OH) on the surface of basalt fibers to form a stable silicon-oxygen bond (Si–O–Si) structure. At the same time, condensation crosslinking may also occur between adjacent silanol groups to form a network structure. This process firmly grafts the piperazinyl group (containing secondary amine groups) onto the fiber surface, providing active sites for subsequent reactions. The entire process is affected by the pH value. An acidic environment is favorable for the hydrolysis reaction of silane, while an increase in temperature accelerates the rate of the condensation reaction.

[0014] Preferably, in step (1), the basalt fibers are successively ultrasonically cleaned with acetone and deionized water for 10 - 20 min; the pH of the system is adjusted to 4 - 5 with glacial acetic acid; the stirring reaction conditions are stirring at 60 - 75 °C for 3 - 6 h.

[0015] Preferably, in step (1), the dosage ratio of basalt fibers, ethanol aqueous solution, and 3-piperazinylpropylmethyldimethoxysilane is 10 g: 150 - 200 mL: 4 - 8 g; the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 80 - 90: 10 - 20.

[0016] (2) Disperse the pretreated fibers in xylene, then add diethyl 2-allylphosphite, and dropwise add BPO under a nitrogen atmosphere. Carry out a reflux reaction, filter, wash, and dry the product to obtain intermediate fibers;

[0017] Grafting reaction initiated by free radicals: Using BPO as a free radical initiator, under heating conditions, BPO first decomposes to form benzoyloxy radicals, and then decarboxylates to form phenyl radicals. These highly active radicals extract hydrogen atoms from the secondary amine groups (–NH–) on the piperazine ring to generate nitrogen radicals. The generated nitrogen radicals initiate a nucleophilic addition attack on the C=C double bond in the diethyl 2-allylphosphite molecule. Subsequently, the carbon radicals terminate the reaction chain by hydrogen extraction or combination with other radicals. The entire reaction must be carried out under a nitrogen atmosphere to prevent oxygen from quenching the free radicals and reducing the grafting efficiency.

[0018] Preferably, in step (2), the dosage ratio of pretreated fibers, xylene, diethyl 2-allylphosphite, and BPO is 10 g: 100 - 150 mL: 2 - 3.5 g: 0.02 - 0.05 g.

[0019] Preferably, in step (2), the reflux reaction conditions are refluxing at 65 - 80 °C for 4 - 7 h; the product is successively washed with acetone and THF 2 - 3 times.

[0020] (3) Disperse the intermediate fibers into the DMF / THF solvent, then add epoxy group SBS and triethylamine, stir evenly, carry out reflux reaction, filter, wash and dry the product to obtain modified basalt fibers.

[0021] Ring-opening addition of epoxy group and secondary amine: Triethylamine is used as an alkaline catalyst. First, it activates the residual secondary amine groups on the fiber surface, enhancing its nucleophilicity. The activated secondary amine anion conducts nucleophilic attack on the epoxy groups in the epoxy group SBS, resulting in the opening of the epoxy ring. Since there are multiple epoxy groups on the SBS molecular chain, one SBS molecule may react with multiple secondary amine groups on the fiber surface to form a network cross-linked structure. At the same time, the hydroxyl groups generated by the reaction may undergo a secondary reaction with the epoxy groups, further enhancing the cross-linking density.

[0022] Preferably, in step (3), the dosage ratio of the intermediate fibers, DMF / THF solvent, epoxy group SBS, and triethylamine is 10 g: 100 - 120 mL: 3 - 7 g: 0.05 - 0.2 g; the volume ratio of DMF to THF in the DMF / THF solvent is 7 - 8: 2 - 3.

[0023] Preferably, in step (3), the reflux reaction conditions are reflux reaction at 200 - 400 r / min and 75 - 90 °C for 7 - 10 h; the product is washed with THF and ethanol 2 - 3 times in sequence.

[0024] Preferably, in step (3), the preparation method of the epoxy group SBS includes the following steps: Take styrene and cyclohexane, stir and heat up to 55 - 65 °C, add n-butyllithium, stir for 30 - 60 min, add butadiene, react for 30 - 60 min, add styrene, react for 20 - 40 min, add propylene oxide, react for 10 - 20 min, add epichlorohydrin, react for 10 - 20 min, polymerize and dry to obtain epoxy group SBS.

[0025] The present invention also claims a preparation method of a modified filler, which includes the following steps: Stir and mix phosphogypsum, quicklime, limestone, and modified basalt fibers at 50 - 80 r / min for 60 - 180 s to obtain the modified filler.

[0026] The present invention also claims an SMA-13 asphalt mixture, which is made of the following components in parts by weight: 4 - 8 parts of SMA-13 asphalt, 4 - 8 parts of modified filler, 50 - 80 parts of coarse aggregate, and 20 - 50 parts of fine aggregate.

[0027] The present invention also claims to protect a preparation method of SMA-13 asphalt mixture, which includes the following steps: preheating coarse aggregates at 160-180°C for 0.5-1.5 h, preheating fine aggregates at 160-180°C for 0.5-1.5 h, and mixing for 60-180 s to obtain an aggregate mixture; preheating SMA-13 asphalt at 130-160°C for 1-3 h, then adding it to the aggregate mixture and mixing for 60-180 s to obtain an intermediate mixture; preheating modified filler at 140-160°C for 0.5-1.5 h, adding it to the intermediate mixture, and stirring for 60-180 s to obtain the SMA-13 asphalt mixture.

[0028] The coarse aggregates are basalt, with specifications of at least one of 3-5 mm, 5-10 mm, 10-15 mm, and 10-20 mm. The crushing value of the coarse aggregates is not more than 28%, the apparent relative density is not less than 2.5, the water absorption rate is not more than 3%, the adhesion to asphalt is not less than Grade 4, and the content of particles with a particle size less than 0.075 mm detected by the water washing method is not more than 1%.

[0029] The fine aggregates are basalt, with a specification of 0-3 mm, an apparent relative density of not less than 2.5, a methylene blue value of not more than 25 g / kg, a sand equivalent of not less than 60%, and an angularity of not less than 30 s.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention provides an SMA-13 asphalt mixture. The SMA-13 asphalt, as the basic binder, provides good adhesion and film-forming properties; the phosphogypsum in the modified filler realizes the resource utilization of industrial by-products, undergoes a hardening reaction with quicklime, neutralizes the acidity of the phosphogypsum, forms a reticular structure with a certain strength, and enhances the early strength of the mixture; limestone, as the aggregate filling material, improves the volume stability and water damage resistance of the mixture; the modified basalt fiber plays a role in enhancing, dispersing stress, and inhibiting crack propagation. At the same time, its surface active groups form chemical bonds with asphalt, improving the interfacial bonding strength. The coarse aggregate basalt forms a strong skeleton structure with its high hardness and excellent crushing value, bearing the main load; while the fine aggregates effectively fill the skeleton gaps, improving the overall density. This combination of optimized ratios makes the asphalt mixture possess excellent high-temperature stability, low-temperature crack resistance, water stability, and fatigue durability, and is particularly suitable for road paving under heavy traffic and extreme climate conditions.

[0032] 2. The present invention provides a modified basalt fiber, achieving synergistic enhancement of multiple functions through three-step surface modification. First, piperazine groups, as a kind of nitrogen-containing heterocyclic compound, have remarkable antioxidant ability, can effectively capture free radicals generated during the aging process of asphalt, block the oxidation chain reaction. At the same time, their basic properties can neutralize acidic components in asphalt, reduce the rate of increase in acid value during the aging process, enabling the modified asphalt mixture to maintain long-term stability under ultraviolet radiation and atmospheric oxidation conditions, and delaying the hardening and embrittlement of asphalt. Second, phosphite groups can decompose and release phosphorus free radicals, which can rapidly terminate the thermal oxidation chain reaction, and can also react with oxygen free radicals to form stable phosphates, cutting off the oxidation chain, thereby effectively decomposing peroxides accumulated during the aging process of asphalt; in addition, it also has a certain anti-ultraviolet degradation effect, capturing free radicals generated by ultraviolet radiation and slowing down the photo-oxidation process on the asphalt surface; the phosphite group and piperazine group can also form a synergistic antioxidant system, constructing an all-round and long-lasting aging protection network; at the same time, in the event of a fire, it can form a charred protective layer, endowing the material with certain flame retardant properties. Third, the introduction of epoxy-based SBS realizes the "bridging" effect between basalt fiber and asphalt. The epoxy groups undergo ring-opening addition reactions with polar groups such as carboxyl and hydroxyl groups in asphalt to form chemical bonding, while the non-polar segments of SBS have good compatibility with alkane components of asphalt. This amphiphilic structure significantly improves the bonding strength at the fiber-asphalt interface, reducing the phenomenon of interfacial debonding; at the same time, the SBS elastomer network endows the asphalt mixture with higher elastic recovery ability and rutting resistance, improving the low-temperature flexibility and fatigue cracking resistance of the mixture. Overall, when this multifunctional modified basalt fiber is used in combination with traditional fillers, a composite reinforcement system with both "rigidity-flexibility-tenacity" is constructed, effectively improving the comprehensive service performance and service life of the asphalt mixture, especially showing excellent performance under conditions of drastic temperature fluctuations and heavy traffic. Detailed Embodiments

[0033] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in detail with reference to embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased through market channels or synthesized from raw materials purchased through market channels.

[0035] Preparation method of epoxy group SBS, comprising the following steps: Take 13 g of styrene and 500 g of cyclohexane, stir and heat up to 60 °C, add 0.6 mL of n-butyllithium, stir for 35 min, add 60 g of butadiene, react for 45 min, add 13 g of styrene, react for 30 min, add 0.2 mL of propylene oxide, react for 12 min, add 0.3 mL of epichlorohydrin, react for 15 min, polymerize and dry to obtain epoxy group SBS.

[0036] The basalt fiber is purchased from Wuhan Qixing New Technology Materials Co., Ltd., with a length of 10 - 30 mm, a diameter of 13 - 17 μm, and a compressive strength of ≥1050 MPa.

[0037] A preparation method of SMA-13 asphalt mixture, comprising the following steps:

[0038] (1) Ultrasonically clean 10 g of basalt fiber with acetone and deionized water for 10 - 20 min in sequence, then immerse it in 150 - 200 mL of ethanol aqueous solution (volume ratio of ethanol to deionized water is 80 - 90:10 - 20), add 4 - 8 g of 3-piperazinylpropylmethyldimethoxysilane, adjust the pH of the system to 4 - 5 with glacial acetic acid, stir and react at 60 - 75 °C for 3 - 6 h, filter, wash and dry the product to obtain pretreated fiber;

[0039] (2) Disperse 10 g of pretreated fiber into 100 - 150 mL of xylene, then add 2 - 3.5 g of diethyl 2-allylphosphite, dropwise add 0.02 - 0.05 g of BPO under a nitrogen atmosphere, reflux and react at 65 - 80 °C for 4 - 7 h, filter the product, wash it with acetone and THF for 2 - 3 times in sequence, and dry to obtain intermediate fiber;

[0040] (3) Disperse 10 g of intermediate fiber into 100 - 120 mL of DMF / THF solvent (volume ratio of DMF to THF is 7 - 8:2 - 3), then add 3 - 7 g of epoxy group SBS and 0.05 - 0.2 g of triethylamine, stir evenly, reflux and react at 200 - 400 r / min and 75 - 90 °C for 7 - 10 h, filter the product, wash it with THF and ethanol for 2 - 3 times in sequence, and dry to obtain modified basalt fiber;

[0041] (4) Mix 10 parts of phosphogypsum, 5 - 8 parts of quicklime, 5 - 60 parts of limestone, and 10 - 30 parts of modified basalt fiber at 50 - 80 r / min for 60 - 180 s to obtain modified filler; preheat 50 - 80 parts of basalt coarse aggregate at 160 - 180 °C for 0.5 - 1.5 h, preheat 20 - 50 parts of basalt fine aggregate at 160 - 180 °C for 0.5 - 1.5 h, and mix for 60 - 180 s to obtain an aggregate mixture; preheat 4 - 8 parts of SMA - 13 asphalt at 130 - 160 °C for 1 - 3 h, then add it to the aggregate mixture and mix for 60 - 180 s to obtain an intermediate mixture; preheat 4 - 8 parts of modified filler at 140 - 160 °C for 0.5 - 1.5 h, add it to the intermediate mixture, and stir for 60 - 180 s to obtain the SMA - 13 asphalt mixture.

[0042] The following are specific examples to further illustrate the present invention.

[0043] Example 1

[0044] A preparation method of SMA - 13 asphalt mixture, comprising the following steps:

[0045] (1) Ultrasonically clean 10 g of basalt fiber with acetone and deionized water for 15 min in sequence, then immerse it in 150 mL of ethanol aqueous solution (the volume ratio of ethanol to deionized water is 90:10), add 8 g of 3 - piperazinylpropylmethyldimethoxysilane, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 75 °C for 3 h, filter, wash, and dry the product to obtain pretreated fiber;

[0046] (2) Disperse 10 g of pretreated fiber into 120 mL of xylene, then add 3.5 g of diethyl 2 - allylphosphite, dropwise add 0.05 g of BPO under a nitrogen atmosphere, reflux and react at 80 °C for 4 h, filter the product, wash it with acetone and THF twice in sequence, and dry to obtain intermediate fiber;

[0047] (3) Disperse 10 g of intermediate fiber into 100 mL of DMF / THF solvent (the volume ratio of DMF to THF is 7:3), then add 7 g of epoxy - SBS and 0.2 g of triethylamine, stir evenly, reflux and react at 400 r / min and 90 °C for 7 h, filter the product, wash it with THF and ethanol twice in sequence, and dry to obtain modified basalt fiber;

[0048] (4) Stir and mix 10 g of phosphogypsum, 8 g of quicklime, 60 g of limestone, and 30 g of modified basalt fiber at 60 r / min for 120 s to obtain modified filler; preheat 800 g of basalt coarse aggregate at 170 °C for 1 h, preheat 500 g of basalt fine aggregate at 170 °C for 1 h, and mix for 120 s to obtain an aggregate mixture; preheat 80 g of SMA-13 asphalt at 150 °C for 2 h, then add it to the aggregate mixture and mix for 120 s to obtain an intermediate mixture; preheat 80 g of modified filler at 150 °C for 1 h, add it to the intermediate mixture, and stir for 120 s to obtain the SMA-13 asphalt mixture.

[0049] Example 2

[0050] A preparation method of an SMA-13 asphalt mixture, comprising the following steps:

[0051] (1) Ultrasonically clean 10 g of basalt fiber with acetone and deionized water for 15 min in sequence, then immerse it in 150 mL of an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 90:10), add 6 g of 3-piperazinylpropylmethyldimethoxysilane, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 70 °C for 4 h, filter, wash, and dry the product to obtain pretreated fiber;

[0052] (2) Disperse 10 g of pretreated fiber in 120 mL of xylene, then add 3.0 g of diethyl 2-allylphosphite, dropwise add 0.04 g of BPO under a nitrogen atmosphere, reflux and react at 75 °C for 5 h, filter the product, wash it with acetone and THF twice in sequence, and dry to obtain intermediate fiber;

[0053] (3) Disperse 10 g of intermediate fiber in 100 mL of a DMF / THF solvent (the volume ratio of DMF to THF is 7:3), then add 6 g of epoxy SBS and 0.15 g of triethylamine, stir evenly, reflux and react at 300 r / min and 85 °C for 8 h, filter the product, wash it with THF and ethanol twice in sequence, and dry to obtain modified basalt fiber;

[0054] (4) Stir and mix 10 g of phosphogypsum, 7 g of quicklime, 40 g of limestone, and 25 g of modified basalt fiber at 60 r / min for 120 s to obtain modified filler; preheat 700 g of basalt coarse aggregate at 170 °C for 1 h, preheat 400 g of basalt fine aggregate at 170 °C for 1 h, and mix for 120 s to obtain an aggregate mixture; preheat 70 g of SMA-13 asphalt at 150 °C for 2 h, then add it to the aggregate mixture and mix for 120 s to obtain an intermediate mixture; preheat 40 - 80 g of modified filler at 150 °C for 1 h, add it to the intermediate mixture, and stir for 120 s to obtain the SMA-13 asphalt mixture.

[0055] Example 3

[0056] A preparation method of SMA-13 asphalt mixture, comprising the following steps:

[0057] (1) Ultrasonically clean 10 g of basalt fibers with acetone and deionized water for 15 min in sequence, then immerse them in 150 mL of ethanol aqueous solution (the volume ratio of ethanol to deionized water is 90:10), add 5 g of 3-piperazinylpropylmethyldimethoxysilane, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 65 °C for 5 h, filter, wash and dry the product to obtain pretreated fibers;

[0058] (2) Disperse 10 g of pretreated fibers in 120 mL of xylene, then add 2.5 g of diethyl 2-allylphosphite, dropwise add 0.03 g of BPO under a nitrogen atmosphere, reflux and react at 70 °C for 6 h, filter the product, wash it twice with acetone and THF in sequence, and dry to obtain intermediate fibers;

[0059] (3) Disperse 10 g of intermediate fibers in 100 mL of DMF / THF solvent (the volume ratio of DMF to THF is 7:3), then add 4 g of epoxy SBS and 0.1 g of triethylamine, stir evenly, reflux and react at 300 r / min and 80 °C for 9 h, filter the product, wash it twice with THF and ethanol in sequence, and dry to obtain modified basalt fibers;

[0060] (4) Stir and mix 10 g of phosphogypsum, 6 g of quicklime, 20 g of limestone, and 15 g of modified basalt fibers at 60 r / min for 120 s to obtain modified filler; preheat 600 g of basalt coarse aggregate at 170 °C for 1 h, preheat 300 g of basalt fine aggregate at 170 °C for 1 h, mix for 120 s to obtain an aggregate mixture; preheat 50 g of SMA-13 asphalt at 150 °C for 2 h, then add it to the aggregate mixture, mix for 120 s to obtain an intermediate mixture; preheat 50 g of modified filler at 150 °C for 1 h, add it to the intermediate mixture, and stir for 120 s to obtain the SMA-13 asphalt mixture.

[0061] Example 4

[0062] A preparation method of SMA-13 asphalt mixture, comprising the following steps:

[0063] (1) Ultrasonically clean 10 g of basalt fibers with acetone and deionized water for 15 min successively, then immerse them in 150 mL of an ethanol aqueous solution (volume ratio of ethanol to deionized water is 90:10), add 4 g of 3-piperazinylpropylmethyldimethoxysilane, adjust the pH of the system to 4.5 with glacial acetic acid, and stir and react at 60 °C for 6 h. Filter, wash, and dry the product to obtain pretreated fibers;

[0064] (2) Disperse 10 g of pretreated fibers in 120 mL of xylene, then add 2 g of diethyl 2-allylphosphite, dropwise add 0.02 g of BPO under a nitrogen atmosphere, and reflux and react at 65 °C for 7 h. Filter the product, wash it twice with acetone and THF successively, and dry it to obtain intermediate fibers;

[0065] (3) Disperse 10 g of intermediate fibers in 100 mL of a DMF / THF solvent (volume ratio of DMF to THF is 7:3), then add 3 g of epoxy SBS and 0.05 g of triethylamine, stir evenly, and reflux and react at 200 r / min and 75 °C for 10 h. Filter the product, wash it twice with THF and ethanol successively, and dry it to obtain modified basalt fibers;

[0066] (4) Stir and mix 10 g of phosphogypsum, 5 g of quicklime, 5 g of limestone, and 10 g of modified basalt fibers at 60 r / min for 120 s to obtain modified filler; preheat 500 g of basalt coarse aggregate at 170 °C for 1 h, preheat 200 g of basalt fine aggregate at 170 °C for 1 h, and mix them for 120 s to obtain an aggregate mixture; preheat 40 g of SMA-13 asphalt at 150 °C for 2 h, then add it to the aggregate mixture and mix for 120 s to obtain an intermediate mixture; preheat 40 g of modified filler at 150 °C for 1 h, add it to the intermediate mixture, and stir for 120 s to obtain the SMA-13 asphalt mixture.

[0067] Comparative Example 1

[0068] A preparation method of an SMA-13 asphalt mixture, comprising the following steps:

[0069] (1) Ultrasonically clean 10 g of basalt fibers with acetone and deionized water for 15 min successively, then immerse them in 150 mL of an ethanol aqueous solution (volume ratio of ethanol to deionized water is 90:10), add 8 g of 3-piperazinylpropylmethyldimethoxysilane, adjust the pH of the system to 4.5 with glacial acetic acid, and stir and react at 75 °C for 3 h. Filter, wash, and dry the product to obtain pretreated fibers;

[0070] (2) Disperse 10 g of the pretreated fiber into 120 mL of xylene, then add 3.5 g of diethyl 2 - allylphosphite, dropwise add 0.05 g of BPO under a nitrogen atmosphere, reflux and react at 80 °C for 4 h. Filter the product, wash it twice with acetone and THF respectively, and dry it to obtain the intermediate fiber;

[0071] (3) Stir and mix 10 g of phosphogypsum, 8 g of quicklime, 60 g of limestone, and 30 g of the intermediate fiber at 60 r / min for 120 s to obtain the modified filler; preheat 800 g of basalt coarse aggregate at 170 °C for 1 h, preheat 500 g of basalt fine aggregate at 170 °C for 1 h, mix them for 120 s to obtain the aggregate mixture; preheat 80 g of SMA - 13 asphalt at 150 °C for 2 h, then add it to the aggregate mixture and mix for 120 s to obtain the intermediate mixture; preheat 80 g of the modified filler at 150 °C for 1 h, add it to the intermediate mixture, and stir for 120 s to obtain the SMA - 13 asphalt mixture.

[0072] Comparative Example 2

[0073] A preparation method of an SMA - 13 asphalt mixture, comprising the following steps:

[0074] (1) Ultrasonically clean 10 g of basalt fiber with acetone and deionized water for 15 min in sequence, then immerse it into 150 mL of an ethanol - aqueous solution (the volume ratio of ethanol to deionized water is 90:10), add 8 g of 3 - piperazinylpropylmethyldimethoxysilane, adjust the pH of the system to 4.5 with glacial acetic acid, stir and react at 75 °C for 3 h. Filter, wash, and dry the product to obtain the pretreated fiber;

[0075] (2) Stir and mix 10 g of phosphogypsum, 8 g of quicklime, 60 g of limestone, and 30 g of the pretreated fiber at 60 r / min for 120 s to obtain the modified filler; preheat 800 g of basalt coarse aggregate at 170 °C for 1 h, preheat 500 g of basalt fine aggregate at 170 °C for 1 h, mix them for 120 s to obtain the aggregate mixture; preheat 80 g of SMA - 13 asphalt at 150 °C for 2 h, then add it to the aggregate mixture and mix for 120 s to obtain the intermediate mixture; preheat 80 g of the modified filler at 150 °C for 1 h, add it to the intermediate mixture, and stir for 120 s to obtain the SMA - 13 asphalt mixture.

[0076] The performance tests were carried out on the asphalt mixtures prepared in Examples 1-4 and Comparative Examples 1-2. The Marshall stability and immersion residue stability were detected by "T0709-2011"; the freeze-thaw splitting strength ratio was detected by "T0729-2000"; the dynamic stability was detected by "T0729-2000". The specimens were subjected to accelerated aging, which was carried out at a temperature of 65 °C and a humidity of 85% for 1000 h, and ultraviolet irradiation of 100 μw / cm 2 . After aging, the above experiments were carried out again to evaluate the effect of aging on the performance of the asphalt mixture. The specific data are shown in Table 1.

[0077] Table 1 Performance test results of asphalt mixture

[0078]

[0079]

[0080] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A modified filler, characterized in that It is made of the following components by weight parts: 10 parts of phosphogypsum, 5 - 8 parts of quicklime, 5 - 60 parts of limestone, and 10 - 30 parts of modified basalt fiber.

2. The modified filler according to claim 1, wherein, The preparation method of the modified basalt fiber includes the following steps: (1) Clean the basalt fiber, then immerse it in an ethanol aqueous solution, add 3 - piperazinylpropylmethyldimethoxysilane, adjust the pH of the system, stir and react, filter, wash, and dry the product to obtain pretreated fiber; (2) Disperse the pretreated fiber in xylene, then add diethyl 2 - allylphosphite, dropwise add BPO under a nitrogen atmosphere, reflux and react, filter, wash, and dry the product to obtain intermediate fiber; (3) Disperse the intermediate fiber in a DMF / THF solvent, then add epoxy - based SBS and triethylamine, stir evenly, reflux and react, filter, wash, and dry the product to obtain modified basalt fiber.

3. The modified filler according to claim 2, wherein In step (1), the basalt fiber is ultrasonically cleaned with acetone and deionized water in sequence for 10 - 20 min; the pH of the system is adjusted to 4 - 5 with glacial acetic acid; the stirring reaction condition is stirring and reacting at 60 - 75 °C for 3 - 6 h.

4. The modified filler according to claim 2, wherein In step (1), the dosage ratio of basalt fiber, ethanol aqueous solution, and 3 - piperazinylpropylmethyldimethoxysilane is 10 g: 150 - 200 mL: 4 - 8 g; the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 80 - 90: 10 - 20.

5. The modified filler according to claim 2, wherein In step (2), the dosage ratio of pretreated fiber, xylene, diethyl 2 - allylphosphite, and BPO is 10 g: 100 - 150 mL: 2 - 3.5 g: 0.02 - 0.05 g.

6. The modified filler according to claim 2, wherein In step (2), the reflux reaction condition is refluxing and reacting at 65 - 80 °C for 4 - 7 h; the product is washed with acetone and THF in sequence for 2 - 3 times.

7. The modified filler according to claim 2, wherein In step (3), the dosage ratio of intermediate fiber, DMF / THF solvent, epoxy - based SBS, and triethylamine is 10 g: 100 - 120 mL: 3 - 7 g: 0.05 - 0.2 g; the volume ratio of DMF to THF in the DMF / THF solvent is 7 - 8: 2 - 3.

8. The modified filler according to claim 2, wherein, In step (3), the reflux reaction condition is refluxing and reacting at 200 - 400 r / min and 75 - 90 °C for 7 - 10 h; the product is washed with THF and ethanol in sequence for 2 - 3 times.

9. An SMA-13 asphalt mixture, characterized in that, It is made of the following components by weight parts: 4 - 8 parts of SMA - 13 asphalt, 4 - 8 parts of modified filler, 50 - 80 parts of coarse aggregate, and 20 - 50 parts of fine aggregate.

10. The preparation method of the SMA-13 asphalt mixture according to claim 9, characterized in that, It includes the following steps: Preheat the coarse aggregate at 160 - 180 °C for 0.5 - 1.5 h, preheat the fine aggregate at 160 - 180 °C for 0.5 - 1.5 h, mix for 60 - 180 s to obtain an aggregate mixture; preheat the SMA - 13 asphalt at 130 - 160 °C for 1 - 3 h, then add it to the aggregate mixture, mix for 60 - 180 s to obtain an intermediate mixture; preheat the modified filler at 140 - 160 °C for 0.5 - 1.5 h, add it to the intermediate mixture, and stir for 60 - 180 s to obtain the SMA - 13 asphalt mixture.

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