Modified steel slag mixture, preparation method thereof and pavement structure

Abstract

This invention provides a modified steel slag mixture, its preparation method, and a pavement structure. The modified steel slag mixture comprises the following raw materials: SBS modified asphalt, basalt aggregate, modified steel slag, and mineral powder. The raw materials for preparing the modified steel slag include: steel slag, hydrophobic silane A, waterborne acrylic polyurethane dispersion, glycidyl methacrylate, and aminosilane. The hydrophobic silane A includes at least one of n-octyltrimethoxysilane, isooctyltriethoxysilane, and n-dodecyltrimethoxysilane. This invention solves the problems of volume instability and insufficient adhesion durability with asphalt caused by the expansion of free oxides upon contact with water in road applications of steel slag.

Description

Technical Field

[0001] This invention relates to the field of road engineering, and more particularly to a modified steel slag mixture, its preparation method, and pavement structure. Background Technology

[0002] Steel slag, an industrial byproduct, is considered an ideal substitute for natural aggregates in road construction due to its high hardness and wear resistance. Its alkaline properties allow for good chemical adhesion to weakly acidic asphalt, and its rough, porous surface also facilitates physical adhesion. Furthermore, steel slag's sharp edges, high strength, and good wear resistance significantly improve the durability and safety of asphalt pavements. However, despite these advantages in road engineering, the utilization rate of steel slag remains low. This is mainly because steel slag contains free calcium oxide and magnesium oxide, which expand in volume upon contact with water, leading to random cracking in the asphalt pavement and severely affecting its water stability and service life.

[0003] To address the water damage problem of steel slag, common pretreatment methods include aging, autoclaving, steam treatment, and carbonation. However, these methods generally suffer from drawbacks such as long processing cycles, low efficiency, complex operation, and high costs, limiting the large-scale application of steel slag. Furthermore, while surface treatment with silicone resins can improve the properties of steel slag to some extent, its brittleness, the need for high-temperature curing, and the use of toxic solvents for dilution present numerous inconveniences in practice. Therefore, developing an efficient, low-cost, and environmentally friendly steel slag modification method is crucial to improving the utilization rate of steel slag in road engineering. Summary of the Invention

[0004] The main objective of this invention is to provide a modified steel slag mixture, its preparation method, and a pavement structure, aiming to solve the problems of volume instability and insufficient adhesion durability with asphalt caused by the expansion of free oxides when steel slag encounters water in road applications.

[0005] To achieve the above objectives, the present invention provides a modified steel slag mixture comprising the following raw materials: SBS modified bitumen, basalt aggregate, modified steel slag, and mineral powder;

[0006] The raw materials for preparing the modified steel slag include: steel slag, hydrophobic silane A, waterborne acrylic polyurethane dispersion, glycidyl methacrylate, and aminosilane.

[0007] The hydrophobic silane A includes at least one of n-octyltrimethoxysilane, isooctyltriethoxysilane, and n-dodecyltrimethoxysilane.

[0008] This invention significantly improves the overall performance of steel slag in asphalt mixtures through the synergistic design of specific components. Specifically, the waterborne acrylic polyurethane dispersion serves as the film-forming matrix, exhibiting excellent flexibility and construction stability; the epoxy groups introduced by glycidyl methacrylate (GMA) can covalently react with the active groups in SBS-modified asphalt, greatly enhancing the interfacial bond strength between steel slag and asphalt; hydrophobic silanes A (such as n-octyltrimethoxysilane) construct a long-lasting hydrophobic layer on the steel slag surface, effectively blocking moisture intrusion and inhibiting the hydration and swelling of free oxides in the steel slag; aminosilanes (such as KH-550) further provide highly reactive -NH2 to strengthen interfacial interactions and lay the foundation for interlayer chemical crosslinking in the double-layer structure. The combined effect of these components enables the modified steel slag in dense-graded asphalt mixtures to possess excellent high-temperature stability, water stability, and fatigue resistance, while also providing material support for the synergistic interlayer functions of permeable pavements.

[0009] In some embodiments, the composition includes the following components by weight: 3-8 parts SBS modified bitumen, 20-45 parts basalt aggregate, 50-65 parts modified steel slag, and 5-8 parts mineral powder.

[0010] Under the above conditions, the volume stability of the mixture is improved, ensuring excellent road performance, and it is also suitable for road engineering projects with high requirements for water stability and durability.

[0011] In some embodiments, the basalt aggregate has a particle size distribution range of 0.075 mm to 4.75 mm.

[0012] Under the above conditions, the reasonable gradation of fine aggregates improves the density and high-temperature deformation resistance of the mixture; on the other hand, it avoids the impact of excessively coarse particles on the surface smoothness.

[0013] The present invention also provides a method for preparing the modified steel slag mixture, comprising the following steps:

[0014] The modified steel slag, the basalt aggregate, the mineral powder, and the modified asphalt are heated and mixed separately to obtain the modified steel slag mixture.

[0015] In some embodiments, the method for preparing the modified steel slag includes the following steps:

[0016] S1. The aqueous acrylic polyurethane dispersion, the hydrophobic silane A, and the glycidyl methacrylate are mixed and reacted to obtain a hybrid dispersion;

[0017] S2. The hybrid dispersion is sprayed onto the surface of the steel slag to obtain hydrophobic steel slag;

[0018] S3. The modified steel slag is obtained by spraying the aminosilane dispersion onto the hydrophobic steel slag a second time and curing it at room temperature.

[0019] The modified steel slag is prepared by first reacting an aqueous acrylic polyurethane dispersion, hydrophobic silane A, and glycidyl methacrylate (GMA) in situ to form a hybrid dispersion, which is then sprayed onto the steel slag surface to construct a dense substrate with both hydrophobicity and epoxy activity. Subsequently, a second coating is applied using an aminosilane dispersion to enrich the surface with highly reactive -NH2 groups. This step-by-step design avoids the aminosilane being embedded during film formation, ensuring that -NH2 is efficiently exposed on the outermost surface of the particles. This allows for strong interactions with acidic components in the asphalt, improving interfacial adhesion and water stability, and also provides reaction sites for interlayer covalent crosslinking with the epoxy groups in the base layer of the double-layer permeable structure.

[0020] In some embodiments, the method for preparing the modified steel slag includes the following steps:

[0021] S1. The aqueous acrylic polyurethane dispersion, the hydrophobic silane A and the glycidyl methacrylate are mixed and reacted in a mass ratio of (80-120):(4-8):(2-5) to obtain a hybrid dispersion;

[0022] S2. The hybrid dispersion is sprayed onto the surface of the steel slag at 3.5% to 5.5% of the steel slag mass, and after standing, hydrophobic steel slag is obtained.

[0023] S3. Prepare a hydrolytic dispersion by mixing 1 to 3 parts of the aminosilane, and spray the hydrolytic dispersion of the aminosilane onto the hydrophobic steel slag a second time at 1.0% to 2.5% of the mass of the steel slag. After drying, the modified steel slag is obtained.

[0024] The present invention also provides a road surface structure, the road surface structure comprising a surface layer and a base layer stacked sequentially, wherein the raw material for preparing the surface layer includes the modified steel slag mixture.

[0025] In some embodiments, the raw materials for preparing the base layer include: steel slag, γ-glycidoxypropyltrimethoxysilane, and 3,3,3-trifluoropropyltrimethoxysilane.

[0026] In some embodiments, the raw materials for preparing the base layer include steel slag and a mixed modifying liquid for surface modification;

[0027] The mixed modified liquid contains γ-glycidoxypropyltrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane in a mass ratio of (3-5):(2-4).

[0028] In this invention, the surface layer uses the aforementioned modified steel slag mixture, which possesses excellent asphalt adhesion, water stability, and structural load-bearing capacity. This invention significantly enhances the interfacial bonding strength between the two layers by constructing a covalent cross-linked network between the amino groups enriched on the surface of the modified steel slag in the surface layer and the epoxy groups on the surface of the modified steel slag in the base layer. This effectively suppresses interlayer relative slippage and interfacial debonding that may occur under traffic loads and environmental effects. This chemical bonding mechanism not only improves the overall structural integrity and fatigue resistance but also "anchors" the spatial positional relationship of the upper and lower skeleton particles at the microscale, thereby maintaining the vertical alignment and long-term connectivity of the permeable pore channels. Based on this, the superhydrophobic properties imparted by the base steel slag after modification with 3,3,3-trifluoropropyltrimethoxysilane can promote the rapid roll-off of rainwater and effectively repel the adhesion of oil and fine particulate pollutants, further preventing pore blockage. This double-layer structure realizes a functional gradient design of strong adhesion and anti-peeling upper layer and fast drainage and anti-clogging lower layer. It not only ensures high permeability efficiency, but also maintains long-term connectivity of pore channels through interlayer covalent bonding, which greatly improves the overall durability of permeable pavement.

[0029] In some embodiments, the method for preparing the pavement structure includes:

[0030] A1. After laying the base course on the roadbed, 2,4,6-tris(dimethylaminomethyl)phenol is applied to its surface to obtain the modified base course;

[0031] A2. The surface layer is laid on the surface of the modified base layer to obtain the road structure.

[0032] DMP-30 significantly promotes in-situ covalent cross-linking between the exposed amino groups on the surface of the modified steel slag in the top layer and the epoxy groups on the surface of the base layer steel slag. This forms a chemical bond network at the interface between the upper and lower layers, which not only firmly anchors the skeletal structure and inhibits interlayer slip, but also effectively maintains the spatial alignment and connectivity of the void channels. Compared to traditional bilayer structures that rely on physical interlocking, this method significantly improves interlayer shear strength and long-term drainage stability.

[0033] A1. After laying the base course on the roadbed, evenly spray an aqueous solution containing 2,4,6-tris(dimethylaminomethyl)phenol onto its surface. The aqueous solution contains 0.5%–1.0% by mass of 2,4,6-tris(dimethylaminomethyl)phenol, 3%–7% by mass of propylene glycol, and the remainder is deionized water. The spraying rate is 1.5–2.5 L / m². 2 The modified base layer is obtained;

[0034] A2. Lay the surface layer onto the modified base layer to obtain the road structure.

[0035] In some embodiments, the method for preparing the base layer includes:

[0036] B1. γ-glycidoxypropyltrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane were mixed and dispersed, and then hydrolyzed to obtain a mixed solution;

[0037] B2. The mixture is sprayed onto the surface of the steel slag and then dried.

[0038] In some embodiments, the preparation method of the substrate includes blending γ-glycidoxypropyltrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane, followed by hydrolysis to form a stable mixture, and then spraying it onto the surface of steel slag to cure it into a film. The epoxy groups provide chemical anchors for subsequent interfacial crosslinking with the amino groups of the surface layer, while the perfluorinated structure endows the substrate with excellent superhydrophobicity, effectively preventing water films, oil stains, and fine particles from clogging the pores.

[0039] In some embodiments, the method for preparing the base layer includes:

[0040] B1. Mix γ-glycidoxypropyltrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane in a mass ratio of (3-5):(2-4), and then perform a hydrolysis reaction to obtain a modified solution;

[0041] B2. The modified liquid is sprayed onto the surface of the steel slag at a concentration of 2.0% to 3.0% of the steel slag mass, and the surface of the steel slag is dried after drying.

[0042] In this invention, the hydrophobicity of the surface layer hydrophobic silane A is sufficient to effectively prevent water from penetrating the interior of the steel slag and inhibit the hydration expansion of free calcium / magnesium oxide. Simultaneously, its molecular structure is compatible with subsequent grafting of aminosilanes, facilitating a strong physical-chemical bond with SBS-modified asphalt. The base layer, as the main body of the drainage channel, needs to maintain high porosity over a long period, facing risks such as rainwater retention, oil deposition, and fine particle blockage. Therefore, a perfluorosilane with extremely low surface energy is introduced. Its -CF3 group endows the steel slag surface with superhydrophobic and even oleophobic properties, promoting rapid rainwater runoff and repelling the adhesion of organic pollutants, thereby achieving anti-clogging functionality. The upper layer emphasizes adhesion and durability, while the lower layer emphasizes long-term permeability—not only fully utilizing the chemical advantages of different hydrophobic silanes, but also solving the technical bottleneck of traditional permeable pavements that are prone to performance degradation due to pore blockage or interlayer debonding through material-structure synergy.

[0043] In some embodiments, the pH of the hydrolysis is 5 to 6. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not 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 creative effort are within the scope of protection of the present invention.

[0045] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0046] To further illustrate the present invention, the following examples are provided:

[0047] Example 1

[0048] A modified steel slag mixture and its preparation method, specifically:

[0049] A densely packed asphalt mixture prepared using modified steel slag, comprising the following components by weight: 4.85 parts SBS modified asphalt, 30 parts basalt aggregate with a particle size of 4.75–0.075 mm, 60 parts modified steel slag, and 5.15 parts limestone powder with a particle size not greater than 0.075 mm.

[0050] The modified steel slag, basalt aggregate, and limestone powder were heated in an oven at 175°C for 2.5 hours, and the SBS modified asphalt was heated to 170°C. Then, the heated modified steel slag, basalt aggregate, and limestone powder were put into a mixer preheated to 180°C and dry-mixed for 30 seconds. Then, the SBS modified asphalt was added and the mixture was continued to be mixed for 90 seconds until uniform, thus obtaining the modified steel slag asphalt mixture.

[0051] The modified steel slag is prepared as follows:

[0052] S1.1 The converter steel slag is crushed and screened to obtain particles with a diameter of 8-18mm. After being thoroughly washed with clean water, it is dried in an oven at 90℃ for 2 hours. To optimize the surface activity, the steel slag is lightly acid-washed (using a dilute acetic acid solution with pH≈5.0 for 10 minutes). After acid washing, it is thoroughly washed with water and dried again at 60℃ for 1 hour.

[0053] S1.2 Add 100 parts of anionic aqueous acrylic polyurethane dispersion with a solid content of 40% and 10 parts of anhydrous ethanol to a high-speed emulsifier. Under shear at 3000 r / min, slowly add 6 parts of n-octyltrimethoxysilane, 3 parts of glycidyl methacrylate (GMA) and 0.5 parts of AIBN, controlling the adding time to 20 min. After the addition is complete, continue stirring for 30 min to obtain pre-emulsion A.

[0054] S1.3 Reduce the rotation speed of preemulsion A to 800 r / min, add 0.8 parts of potassium methylsilicate aqueous solution (mass concentration 10%), adjust the pH to 8.0, react for 1 h, and obtain hybrid dispersion B;

[0055] S2. The hybrid dispersion B is evenly sprayed onto the surface of the dried steel slag obtained in step S1 using an atomizing nozzle at 4.5% of the steel slag mass, and left to stand for 30 minutes to obtain hydrophobic steel slag.

[0056] S3. Subsequently, 1.5 parts of γ-aminopropyltriethoxysilane (KH-550) and 50 parts of deionized water were mixed in a disperser at a speed of 200 r / min. Hydrochloric acid catalyst was added to control the pH of the mixture at 5-6. After reacting for 1 h, a hydrophilic silane hydrolysis product was obtained. This product was prepared into a surface grafting solution and sprayed a second time at 1.5% of the steel slag mass. The mixture was stirred for another 3 min. Finally, it was cured at room temperature for 1.5 h and then dried at 60 °C for 1.5 h to obtain modified steel slag.

[0057] A road surface structure consists of, from top to bottom: surface layer and base layer;

[0058] The specific construction methods are as follows:

[0059] A1. First, level and compact the roadbed to ensure that the bearing capacity meets the design requirements; then lay the base course, and spread the prepared base course modified steel slag evenly to the design thickness (50mm) using a paver or manually. Then, use a light vibratory roller to statically compact once and then micro-vibrate once to avoid over-compaction which would reduce the porosity. After compaction, evenly sprinkle a transparent solution of 2.0L / m² of 0.8wt% 2,4,6-tris(dimethylaminomethyl)phenol, 5wt% propylene glycol and the remainder deionized water on its surface.

[0060] A2. Spread the modified steel slag mixture on the base course to a thickness of 30mm, using the same spreading process as the base course; compaction is performed by using a double-drum roller for 2-3 static passes (speed 1.5km / h) to ensure stable interlocking of surface particles and a smooth surface.

[0061] The preparation method of the modified steel slag at the base layer is as follows:

[0062] B1.1 Take the same source of converter steel slag, screen to obtain particles with a diameter of 5~12mm, wash, dry at 100℃ for 3h and lightly acid wash (pH 5.0, 10 min) for later use;

[0063] B1.2 Preparation of epoxy-hydrophobic composite modification solution: Dissolve 4 parts of γ-glycidoxypropyltrimethoxysilane (KH-560) and 2 parts of 3,3,3-trifluoropropyltrimethoxysilane in 94 parts of anhydrous ethanol, add 0.5 parts of deionized water and 0.2 parts of glacial acetic acid, and stir at room temperature for 45 min to obtain the modification solution; spray the modification solution evenly onto the surface of the base steel slag at 2.5% of the steel slag mass, and then dry at 60℃ for 1.5 h.

[0064] Example 2

[0065] The difference between this embodiment and Embodiment 1 is that in step S3, the amount of γ-aminopropyltriethoxysilane (KH-550) applied in the second spray is 1.0% of the mass of the steel slag, while the rest of the preparation process and road structure construction method are the same as in Embodiment 1.

[0066] Example 3

[0067] A modified steel slag mixture and its preparation method, specifically:

[0068] A densely packed asphalt mixture prepared using modified steel slag, comprising the following components by weight: 4.85 parts SBS modified asphalt, 30 parts basalt aggregate with a particle size of 4.75–0.075 mm, 60 parts modified steel slag, and 5.15 parts limestone powder with a particle size not greater than 0.075 mm.

[0069] The modified steel slag, basalt aggregate, and limestone powder were heated in an oven at 175°C for 2.5 hours, and the SBS modified asphalt was heated to 170°C. Then, the heated modified steel slag, basalt aggregate, and limestone powder were put into a mixer preheated to 180°C and dry-mixed for 30 seconds. Then, the SBS modified asphalt was added and the mixture was continued to be mixed for 90 seconds until uniform, thus obtaining the modified steel slag asphalt mixture.

[0070] The modified steel slag is prepared as follows:

[0071] S1.1 The converter steel slag is crushed and screened to obtain particles with a diameter of 8-18mm. After being thoroughly washed with clean water, it is dried in an oven at 90℃ for 2 hours. In order to optimize the surface activity, the steel slag is lightly acid-washed (using a dilute acetic acid solution with pH≈5.2 for 12 minutes). After acid washing, it is thoroughly washed with water and dried again at 60℃ for 1 hour.

[0072] S1.2 Add 105 parts of anionic aqueous acrylic polyurethane dispersion with a solid content of 40% and 10 parts of anhydrous ethanol to a high-speed emulsifier. Under shear at 3000 r / min, slowly add 7 parts of n-octyltrimethoxysilane, 2.8 parts of glycidyl methacrylate (GMA) and 0.5 parts of AIBN, controlling the adding time to 20 min. After the addition is complete, continue stirring for 30 min to obtain pre-emulsion A.

[0073] S1.3 Reduce the rotation speed of preemulsion A to 800 r / min, add 0.8 parts of potassium methylsilicate aqueous solution (mass concentration 10%), adjust the pH to 8.0, react for 1 h, and obtain hybrid dispersion B;

[0074] S2. The hybrid dispersion B is evenly sprayed onto the surface of the dried steel slag obtained in step S1 using an atomizing nozzle at 4.8% of the steel slag mass, and left to stand for 25 minutes to obtain hydrophobic steel slag.

[0075] S3. Subsequently, 1.8 parts of γ-aminopropyltriethoxysilane (KH-550) and 50 parts of deionized water were mixed in a disperser at a speed of 200 r / min. Hydrochloric acid catalyst was added to control the pH of the mixture at 5-6. After reacting for 1 h, hydrophilic silane hydrolysis product was obtained, which was prepared into a surface grafting solution. The solution was then sprayed with a secondary atomization at 1.8% of the steel slag mass, and stirred for another 3 min. Finally, it was cured at room temperature for 1.2 h and then dried at 60 °C for 1.5 h to obtain modified steel slag.

[0076] A road surface structure consists of, from top to bottom: surface layer and base layer;

[0077] The specific construction methods are as follows:

[0078] A1. First, the roadbed is leveled and compacted to ensure that the bearing capacity meets the design requirements. Then, the base course is laid. The prepared modified steel slag base course is evenly spread to the design thickness (50mm) using a paver or manually. Then, a light vibratory roller is used for static compaction once and micro-vibration once to avoid over-compaction which would reduce porosity. After compaction, 2.0L / m² of cement is evenly sprayed on its surface. 2 A clear solution of 0.7 wt% 2,4,6-tris(dimethylaminomethyl)phenol, 6 wt% propylene glycol and the balance deionized water;

[0079] A2. Spread the modified steel slag mixture on the base course to a thickness of 30mm, using the same spreading process as the base course; compaction is performed using a double-drum roller with static compaction for 2-3 passes (speed 1.5km / h) to ensure stable interlocking of surface particles and a smooth surface. The preparation method of the modified steel slag for the base course is as follows:

[0080] B1.1 Take the same source of converter steel slag, screen to obtain particles with a diameter of 5~12mm, wash, dry at 100℃ for 3h and lightly acid wash (pH 5.2, 12 min) for later use;

[0081] B1.2 Preparation of epoxy-hydrophobic composite modification solution: Dissolve 4 parts of γ-glycidoxypropyltrimethoxysilane (KH-560) and 3 parts of 3,3,3-trifluoropropyltrimethoxysilane in 94 parts of anhydrous ethanol, add 0.5 parts of deionized water and 0.3 parts of glacial acetic acid, control the hydrolysis pH at 5.2-5.5, and stir at room temperature for 45 min to obtain the modification solution; spray the modification solution evenly onto the surface of the base steel slag at 2.5% of the steel slag mass, and then dry at 60℃ for 1.5 h.

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is that no aminosilane was added, while the remaining components and all construction steps are the same as in Example 1.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that no epoxy silane was added, while the remaining components and all construction steps are the same as in Example 1.

[0086] Comparative Example 3

[0087] The difference between this comparative example and Example 1 is that the steel slag modification in the base layer is replaced with n-octyltrimethoxysilane instead of 3,3,3-trifluoropropyltrimethoxysilane, and the steel slag in the surface layer is replaced with 3,3,3-trifluoropropyltrimethoxysilane instead of n-octyltrimethoxysilane, while the other conditions are the same.

[0088] Test Example 1

[0089] This test example simulates the initial permeability and water stability tests of the double-layer permeable pavement structures prepared in the examples and comparative examples, conducted immediately after construction and before opening to traffic. Follow-up tests were then performed at 3-month intervals to evaluate the long-term retention of their drainage function. Tests were conducted according to the "Field Testing Procedures for Highway Subgrade and Pavement" (JTG 3450—2019) T0971—2019 "Test Method for Pavement Permeability Coefficient" and the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG3410—2025). The test results are shown in Table 1.

[0090] Table 1. Performance Testing

[0091]

[0092] Test Example 1 evaluated the performance of the double-layer permeable pavements prepared in Examples 1-3, and the results are shown in Table 1. The permeability coefficient of all examples was above 6100 mL / min, significantly better than the minimum requirement of 3000 mL / min specified in the "Technical Specification for Design and Construction of Drainage Asphalt Pavement" (JTG / T 3350-03-2020). Simultaneously, the residual stability after immersion exceeded 96%, achieving excellent resistance to water damage while ensuring efficient drainage.

[0093] This invention employs a two-step functionalization design for the surface-modified steel slag. First, a flexible hydrophobic underlayer composed of waterborne acrylic polyurethane, hydrophobic silane, and glycidyl methacrylate is formed on the steel slag surface. This effectively blocks moisture intrusion to inhibit the expansion of free oxides, while simultaneously introducing epoxy active groups to enhance chemical adhesion to asphalt. Then, a secondary spraying with amino silane enriches the amino groups at a high density on the outermost surface of the particles, strengthening the interfacial interaction with asphalt and reserving reaction sites for interlayer crosslinking. Secondly, the base layer steel slag is synergistically modified with γ-glycidoxypropyltrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane, simultaneously constructing an epoxy functional layer and a superhydrophobic layer on the surface. The former provides chemical anchors for crosslinking with the surface layer's –NH2, while the latter endows the base layer with excellent self-cleaning and anti-clogging capabilities, ensuring long-term stability of high porosity. Applying 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) to the base layer surface as a catalyst promotes the formation of a covalent cross-linked network between the surface layer –NH2 and the base layer epoxy groups. This not only significantly improves the interlayer shear strength and inhibits slippage and delamination, but also "locks" the spatial alignment of the voids between the upper and lower layers from a microstructural perspective. This achieves high permeability efficiency (permeability coefficient > 6000 mL / min) while ensuring water stability (immersion residual stability > 96%) and long-term drainage function without attenuation. This truly solves the technical bottleneck of poor durability caused by interlayer failure or pore blockage in traditional permeable pavements.

[0094] In summary, the above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the specification and contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A pavement structure, the pavement structure comprising a base course and a surface course stacked sequentially, wherein the surface course is prepared from a modified steel slag mixture; The base layer is prepared from raw materials including: Steel slag, γ-glycidoxypropyltrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane; The method for preparing the base layer includes: B1. γ-glycidoxypropyltrimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane were mixed and dispersed, and then hydrolyzed to obtain a mixed solution; B2. The mixture is sprayed onto the surface of the steel slag and then dried; The construction method for the road surface structure includes: A1. After laying the base course on the roadbed, 2,4,6-tris(dimethylaminomethyl)phenol is applied to its surface to obtain the modified base course; A2. The surface layer is laid on the surface of the modified base layer to obtain the road structure; The modified steel slag mixture comprises, by weight, the following components: 3-8 parts SBS modified bitumen, 20-45 parts basalt aggregate, 50-65 parts modified steel slag, and 5-8 parts mineral powder; The raw materials for preparing the modified steel slag include: steel slag, hydrophobic silane A, waterborne acrylic polyurethane dispersion, glycidyl methacrylate, and aminosilane. The hydrophobic silane A includes at least one of n-octyltrimethoxysilane, isooctyltriethoxysilane, and n-dodecyltrimethoxysilane; The preparation method of the modified steel slag mixture includes the following steps: The modified steel slag, the basalt aggregate, the mineral powder, and the SBS modified asphalt are heated and mixed separately to obtain the modified steel slag mixture; The method for preparing the modified steel slag includes the following steps: S1. The aqueous acrylic polyurethane dispersion, the hydrophobic silane A, and the glycidyl methacrylate are mixed and reacted to obtain a hybrid dispersion; S2. The hybrid dispersion is sprayed onto the surface of the steel slag to obtain hydrophobic steel slag; S3. The modified steel slag is obtained by spraying the hydrophobic steel slag with the dispersion of aminosilane a second time and curing it at room temperature.

2. The pavement structure of claim 1, wherein, The basalt aggregate has a particle size distribution range of 0.075 mm to 4.75 mm.

3. The pavement structure of claim 1, wherein, The particle size distribution range of the steel slag is 8–18 mm.

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