High-performance layered modified full-structure steel slag asphalt pavement and construction method thereof

Abstract

The invention discloses a high-performance layered modified full-structure steel slag asphalt pavement and a construction method thereof, and belongs to the technical field of road engineering. The structure is composed of an upper surface layer, a middle surface layer and a lower surface layer, each layer is paved by adopting a mixture prepared from steel slag aggregate with the doping amount not less than 80% and special modified asphalt, and the upper surface layer adopts QT-ER2 epoxy modified asphalt, so that the upper surface layer is endowed with ultrahigh rut resistance, skid resistance and durability; the middle surface layer adopts QT-HM3 high-viscosity toughening modified asphalt, so that excellent high-temperature stability is guaranteed; the lower surface layer is made of QT-M30 composite reinforced modified asphalt, and excellent fatigue resistance and water stability are provided. By means of the layer position adaptation design, the three problems of uneven performance, volume expansion and low utilization rate in steel slag application are systematically solved, a special construction technology is matched, efficient resource utilization of the steel slag is achieved, the comprehensive performance of the road surface is remarkably improved, the service life of the road surface is remarkably prolonged, the whole-cycle cost is reduced, and economic benefits and environmental protection benefits are remarkable.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to a high-performance layered modified full-structure steel slag asphalt pavement and its construction method. Background Technology

[0002] With the continuous and rapid development of my country's steel industry, the output of steel slag, as a major industrial solid waste, has been increasing year by year. Statistics show that my country's annual steel slag production has exceeded 160 million tons, with a huge historical stockpile, but the comprehensive utilization rate is still below 30%. The massive open-air stockpiling of steel slag not only occupies valuable land resources but also easily leads to a series of serious environmental problems such as dust pollution, soil alkalization, and groundwater pollution. On the other hand, traditional road construction heavily relies on the mining of natural sand and gravel aggregates; long-term, large-scale predatory mining has led to ecological crises such as mountain destruction, riverbed damage, and resource depletion. Therefore, promoting the large-scale resource utilization of steel slag in road engineering is a major strategic requirement for achieving the goal of "zero-waste cities" and ensuring the sustainable development of transportation infrastructure.

[0003] Steel slag, due to its advantages such as hardness, excellent wear resistance, high crushing value, and good adhesion to asphalt, is considered an ideal material to replace natural aggregates in asphalt pavement structures. This not only "turns waste into treasure" and utilizes a huge amount of solid waste, but also reduces dependence on natural mineral resources, resulting in significant environmental and economic benefits.

[0004] However, despite years of research, the large-scale and high-value application of steel slag in asphalt pavements has consistently faced three core technological bottlenecks, resulting in its application being largely limited to test sections or base courses, and failing to achieve widespread application across the entire structural layer:

[0005] First, there is insufficient performance adaptability. Asphalt pavement is a layered structural system, with the upper, middle, and lower layers bearing different mechanical and functional requirements: the upper layer directly bears vehicle loads, wear, and environmental effects, requiring excellent anti-skid, anti-rutting, anti-aging, and anti-cracking properties; the middle layer is the main load-bearing layer, requiring excellent high-temperature stability and shear deformation resistance; and the lower layer requires good fatigue cracking resistance and water stability. Existing technologies typically use a single modifier (such as SBS modified asphalt) or a general modification scheme to treat asphalt mixtures containing steel slag, lacking a fine distinction between the functions of each layer. This "one-size-fits-all" approach cannot meet the differentiated performance requirements of each structural layer, leading to an imbalance in the overall pavement performance, making it prone to localized defects such as rutting, shoving, and fatigue cracking, and making it difficult to guarantee a long pavement life.

[0006] Secondly, the volume stability of steel slag poses a significant risk. The free calcium oxide (f-CaO) and free magnesium oxide (f-MgO) contained in steel slag are its Achilles' heel. These substances undergo a slow, delayed hydration reaction upon contact with water during the pavement's service life, leading to volume expansion. If the modified asphalt lacks sufficient coating, adhesion, and toughness to effectively suppress this expansion stress, it can cause micro-cracks, bulges, and even structural damage within the mixture, severely jeopardizing the long-term durability and service safety of the pavement. Most existing technologies mitigate this risk by simply extending the aging time of steel slag or reducing its dosage, failing to provide a systematic solution from the root cause of material modification.

[0007] Third, the resource utilization efficiency and economic viability are low. Limited by the aforementioned performance and stability issues, the current engineering practice generally uses low levels of steel slag (usually below 50%), and it is mostly limited to a single structural layer (such as the surface layer or base layer), failing to achieve efficient utilization across the entire pavement structure. This low-level utilization model neither fully utilizes the massive stockpiles of steel slag nor leverages its high-strength properties to enhance the overall load-bearing capacity of the pavement. Furthermore, the increased maintenance costs due to performance uncertainties also diminish its economic advantages throughout its life cycle.

[0008] Therefore, there is an urgent need in this field for a novel technological solution that can systematically and simultaneously address the three major challenges of performance adaptation, volume stability, and efficient utilization, thereby enabling the high-volume, high-performance, and long-life application of steel slag in various structural layers of asphalt pavements. This is not only crucial for promoting the high-value utilization of industrial solid waste, but also an essential requirement for building green, durable, and economical highways. Summary of the Invention

[0009] Objective of the invention: To address the above-mentioned problems, this invention provides a high-performance layered modified full-structure steel slag asphalt pavement and its construction method.

[0010] The technical solution is a high-performance layered modified full-structure steel slag asphalt pavement. The pavement structure includes a top layer, a middle layer and a bottom layer from top to bottom. Each layer is paved with high-volume steel slag asphalt mixture modified with a special modifier, wherein steel slag aggregate accounts for more than 80% of the total mass of aggregate.

[0011] The upper layer is made of epoxy-modified steel slag asphalt mixture, and its binder is QT-ER2 epoxy-modified asphalt;

[0012] The intermediate layer uses high-viscosity toughened modified steel slag asphalt mixture, and its binder is QT-HM3 high-viscosity toughened modified asphalt.

[0013] The lower layer uses a composite reinforced modified steel slag asphalt mixture, and its binder is QT-M30 composite reinforced modified asphalt.

[0014] Preferably, in the top layer epoxy-modified steel slag asphalt mixture, the QT-ER2 epoxy-modified asphalt is composed of base asphalt and QT-ER2 epoxy system, the QT-ER2 epoxy system is composed of E51 epoxy resin, amine curing agent and additives, and its dosage is 30%-35% of the mass of base asphalt; the gradation of the mixture is SMA-13 ​​or AC-13.

[0015] Preferably, the technical indicators of the QT-ER2 epoxy modified asphalt meet the following requirements: tensile strength at 23℃ ≥ 1.5MPa, elongation at break ≥ 180%, and construction allowance time ≥ 180min; the technical indicators of the top layer epoxy modified steel slag asphalt mixture meet the following requirements: dynamic stability at 60℃ ≥ 50,000 cycles / mm, low-temperature flexural strain at -10℃ ≥ 3,000με, and skid resistance attenuation rate ≤ 15.2% after 600,000 cycles.

[0016] Preferably, in the intermediate layer high-viscosity toughened modified steel slag asphalt mixture, the QT-HM3 high-viscosity toughened modified asphalt is composed of base asphalt and QT-HM3 composite modifier. The QT-HM3 composite modifier is a compound of SBS modifier and desulfurized rubber particles, and its dosage is not less than 5% of the mass of base asphalt; the gradation of the mixture is AC-20.

[0017] Preferably, the technical indicators of the QT-HM3 high-viscosity toughened modified asphalt meet the following requirements: penetration at 25℃ 40-60 (0.1mm), softening point ≥80℃, and dynamic viscosity at 60℃ ≥100,000 Pa·s; the technical indicators of the intermediate layer high-viscosity toughened modified steel slag asphalt mixture meet the following requirements: dynamic stability at 70℃ ≥3000 times / mm, and freeze-thaw splitting strength ratio ≥90%.

[0018] Preferably, in the lower layer composite reinforced modified steel slag asphalt mixture, the QT-M30 composite reinforced modified asphalt is composed of base asphalt and QT-M30 composite modifier, wherein the QT-M30 composite modifier is mainly composed of linearized active waste rubber that has undergone desulfurization treatment, and its dosage is not less than 4.5% of the mass of base asphalt; the gradation of the mixture is AC-25.

[0019] Preferably, the technical indicators of the QT-M30 composite reinforced modified asphalt meet the following requirements: penetration at 25℃ 40-80 (0.1mm), ductility at 5℃ ≥30cm, and softening point ≥70℃; the technical indicators of the lower layer composite reinforced modified steel slag asphalt mixture meet the following requirements: low-temperature flexural strain at -10℃ ≥3000με, and freeze-thaw splitting strength ratio ≥90%.

[0020] This invention also provides a construction method for high-performance layered modified full-structure steel slag asphalt pavement, comprising the following steps:

[0021] S1: Raw material preparation and inspection: The steel slag aggregate is aged to ensure that the free calcium oxide (f-CaO) content meets the specifications; QT-ER2 epoxy system, QT-HM3 composite modifier, and QT-M30 composite modifier are prepared or procured respectively.

[0022] S2: Preparation of modified asphalt:

[0023] S2a: At the mixing plant, QT-HM3 composite modifier is mixed with base asphalt heated to 175-185℃ using a high-speed shearing process to prepare QT-HM3 high-viscosity toughened modified asphalt for the intermediate surface layer;

[0024] S2b: At the mixing plant, the QT-M30 composite modifier is mixed with the base asphalt heated to 170-180℃ using a mixing and development process to prepare the QT-M30 composite reinforced modified asphalt for the lower layer.

[0025] S3: Mixing of the mixture:

[0026] S3a: Mixing of the lower layer aggregate: Heat the lower layer aggregate (steel slag content ≥80%) to 185-190℃ and mix it with the QT-M30 composite reinforced modified asphalt prepared in S2b at 180-185℃;

[0027] S3b: Mixing of intermediate surface course aggregate: Heat the intermediate surface course aggregate (steel slag content ≥80%) to 190-195℃ and mix it with the QT-HM3 high viscosity toughened modified asphalt prepared in S2a at 185-190℃;

[0028] S3c: Top layer mixture mixing: The synchronous spraying and mixing process is adopted. The top layer aggregate (100% steel slag content) is heated to 190-195℃, first dry-mixed with the base asphalt heated to 150-160℃, and then wet-mixed with the pre-mixed QT-ER2 epoxy system. The discharge temperature is controlled at 170-185℃.

[0029] S4: Mixture transportation and paving: Transport vehicles shall be covered and insulated throughout the entire process; the paving temperature of the lower and middle layers shall not be lower than 165℃, and the paving temperature of the upper layer shall not be lower than 150℃;

[0030] S5: Roll forming:

[0031] S5a: Sub-layer compaction: Compaction is carried out using a combination of heavy-duty pneumatic roller and double-drum vibratory roller, with an initial compaction temperature of not less than 160℃.

[0032] S5b: Intermediate surface layer compaction: Compaction is carried out using a double-drum vibratory roller, with an initial compaction temperature of not less than 165℃;

[0033] S5c: Top layer compaction: A double-drum vibratory roller is used for close-following, slow-speed, high-frequency, low-amplitude compaction. The initial compaction temperature is not lower than 145℃, and the final compaction temperature is not lower than 90℃.

[0034] Preferably, in step S1, the aging time of the steel slag aggregate is not less than 6 months.

[0035] Preferably, in step S3c, the total time from the start of mixing the QT-ER2 epoxy system with asphalt to the completion of mixing and discharge is strictly controlled within the residence time of the epoxy system of 180 minutes.

[0036] Beneficial effects: This invention, through layered functional design, systematically solves three major problems of performance imbalance, expansion risks, and low utilization rate of steel slag asphalt pavement, significantly improving the overall performance and service life of the pavement. This technology achieves high-volume resource utilization of steel slag in the entire structural layer, reducing the total life cycle cost while ensuring excellent road performance, thus possessing significant economic benefits and environmental value. Attached Figure Description

[0037] Figure 1 This is a flowchart of the construction method of the present invention. Detailed Implementation

[0038] The technical solution 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 some embodiments of the present invention, and not all 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 protection scope of the present invention.

[0039] Example 1: Highway surface layer (epoxy-modified steel slag ultrathin overlay)

[0040] 1. Application Scenarios:

[0041] A highway is undergoing preventative maintenance. The original pavement structure is intact, but slight wear and reduced skid resistance have appeared on the surface. The plan is to repair and upgrade it using a 2.5cm thick ultra-thin overlay.

[0042] 2. Structural Design:

[0043] Layer: Top layer (ultra-thin cover layer)

[0044] Thickness: 2.5 cm;

[0045] Mixture type: Epoxy-modified steel slag asphalt mixture;

[0046] Grading: AC-5 (fine gradation);

[0047] Steel slag content: 100% (completely replaces natural aggregates).

[0048] 3. Materials and proportions:

[0049] Aggregate: (1# (5-10mm): 2# (3-5mm): 3# (0.6-3mm): 4# (0-0.6mm): Mineral powder = 5:53:27:8:7);

[0050] cementitious material:

[0051] Base asphalt: SBS modified asphalt (PG 76-22), with a dosage of 6.0% of the mixture mass.

[0052] QT-ER2 epoxy system: It is made by mixing E51 epoxy resin and amine curing agent at a mass ratio of 2.3:1, and its dosage is 32% of the mass of the base asphalt.

[0053] Target mix ratio: aggregate : asphalt (including epoxy system) = 94 : 6.

[0054] 4. Key construction techniques:

[0055] Mixing: A synchronous spray mixing plant is used. First, the steel slag aggregate is heated to 195℃±5℃ and dry-mixed with SBS modified asphalt at 165℃ for 10 seconds. Then, the premixed QT-ER2 epoxy system is added, and the mixture is quickly wet-mixed for 45 seconds to ensure uniformity before discharge. The discharge temperature is controlled above 175℃.

[0056] Transportation and paving: Transport vehicles are equipped with double-layered covers for insulation and are quickly transported to the site. The paving temperature is not lower than 165℃, and the paver operates at a uniform speed and continuously.

[0057] Compaction: An 11-ton double-drum roller is used for close-contact compaction. The initial compaction temperature (one pass of static compaction + one pass of vibratory compaction) should not be lower than 155℃, and the final compaction temperature (one pass of static compaction) should not be lower than 110℃. The entire compaction process must be completed within the epoxy system's residence time (180 minutes).

[0058] 5. Performance Verification: After molding, the pavement core samples were tested, and the results are shown in Table 1 below:

[0059] Table 1. Performance Comparison of Epoxy-Modified Steel Slag Ultrathin Overlays for Highways

[0060]

[0061] Two years after the road opened to traffic, the ultra-thin overlay showed no ruts or cracks on its surface and exhibited extremely low degradation in anti-skid performance, successfully achieving the goal of long-life maintenance.

[0062] Example 2: New Class I Highway Construction Project (Full Structural Application)

[0063] 1. Application scenario: A newly built first-class highway with a high proportion of heavy traffic, requiring high load-bearing capacity and long service life in its design.

[0064] 2. Structural Design:

[0065] Bottom layer: 8cm, AC-25, steel slag content 85%;

[0066] Middle layer: 6cm, AC-20, steel slag content 80%;

[0067] Top layer: 4cm, SMA-13, steel slag content 100%.

[0068] 3. Materials and proportions:

[0069] Lower layer:

[0070] Cementitious material: QT-M30 composite reinforced modified asphalt (QT-M30 modifier added externally at 4.8%);

[0071] Oil-stone ratio: 4.3%.

[0072] Middle layer:

[0073] Cementitious material: QT-HM3 high-viscosity toughened modified asphalt (QT-HM3 modifier added externally at 5.2%);

[0074] Oil-stone ratio: 4.6%.

[0075] Top layer:

[0076] Cementitious material: QT-ER2 epoxy-modified asphalt (epoxy system content is 33% of the asphalt mass);

[0077] Oil-stone ratio: 6.3%.

[0078] 4. Key construction techniques:

[0079] Layered mixing and transportation: Production is carried out simultaneously in three mixing plants according to their respective processes. The lower and middle layers of modified asphalt are pre-mixed in the factory; the upper layer of epoxy asphalt is simultaneously sprayed and mixed on-site. All vehicles transporting the mixture are strictly insulated.

[0080] Layered paving and compaction:

[0081] The lower layer: paving temperature ≥165℃; heavy pneumatic tire roller (initial compaction) + double steel drum roller (secondary compaction, final compaction) combination rolling.

[0082] Intermediate layer: paving temperature ≥170℃; vibratory compaction using a double-drum roller.

[0083] Top layer: paving temperature ≥155℃; compacted by a double-drum roller with close following, slow speed, high frequency and low amplitude.

[0084] Interlayer bonding: Before each layer is laid, apply tack coat evenly to ensure interlayer bonding.

[0085] 5. Performance verification and economic benefits: as shown in Table 2.

[0086] Table 2 Comparison of Performance of All-Structure Steel Slag Pavement on Class I Highways

[0087]

[0088] Economic efficiency: Although the cost of the modifier increases by about 15%, the overall construction cost decreases by about 5% because the cost of steel slag aggregate is 40% lower than that of natural aggregate and the transportation distance is shorter. It is estimated that the life-cycle maintenance cost can be reduced by more than 30% due to improved durability. This invention not only comprehensively improves the physical quality of the pavement (rutting resistance, structural strength), but also achieves a reduction in construction costs and a significant optimization of life-cycle costs through high-volume utilization of steel slag, achieving a high degree of unity between economic and social benefits.

[0089] Example 3: Heavy-duty road surface layer in port area (high-toughness and high-elasticity composite structure)

[0090] 1. Application Scenarios:

[0091] The heavy-duty road in a port container yard is subjected to extreme heavy loads, slow traffic, and frequent starts and stops, requiring extremely high resistance to rutting and fatigue at high temperatures.

[0092] 2. Structural Design:

[0093] Layer: Top layer (high-strength rutting-resistant layer)

[0094] Thickness: 5 cm;

[0095] Mixture type: High-viscosity, toughened modified steel slag asphalt mixture (reinforced);

[0096] Grading: AC-16 (coarse gradation, dense skeleton structure);

[0097] Steel slag content: 90%.

[0098] 3. Materials and proportions:

[0099] Cementitious material: QT-HM3 high-viscosity toughened modified asphalt (QT-HM3 modifier dosage increased to 6.0%), using hard asphalt as the base asphalt (PG 82-22).

[0100] Oil-stone ratio: 4.8%.

[0101] Proportioning: Designed using the volumetric method to ensure the formation of a strong skeletal structure.

[0102] 4. Key construction techniques:

[0103] Mixing: Increase the mixing temperature to 195℃±5℃ and extend the dry mixing time to ensure uniform distribution of coarse steel slag particles.

[0104] Compaction: High-intensity compaction is carried out using a large-tonnage double-drum roller to ensure a compaction degree of over 98%.

[0105] 5. Performance Verification: Heavy-duty rutting tests and four-point bending fatigue tests were conducted under simulated port conditions. The results are shown in Table 3.

[0106] Table 3 Comparison of Surface Layer Performance of Heavy-Duty Roads in Port Areas

[0107]

[0108] This solution is specifically designed for extreme heavy-load conditions, demonstrating that the modifier technology in this invention can be flexibly adapted and provides ultra-high-performance pavement solutions for special occasions through the high strength characteristics of steel slag.

[0109] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A high-performance layered modified full-structure steel slag asphalt pavement, characterized in that, The road structure consists of a top layer, a middle layer and a bottom layer from top to bottom. Each layer is constructed using high-volume steel slag asphalt mixture modified with a special modifier, in which steel slag aggregate accounts for more than 80% of the total aggregate mass. The upper layer is made of epoxy-modified steel slag asphalt mixture, and its binder is QT-ER2 epoxy-modified asphalt; The intermediate layer uses high-viscosity toughened modified steel slag asphalt mixture, and its binder is QT-HM3 high-viscosity toughened modified asphalt. The lower layer uses a composite reinforced modified steel slag asphalt mixture, and its binder is QT-M30 composite reinforced modified asphalt.

2. The high-performance layered modified full-structure steel slag asphalt pavement according to claim 1, characterized in that: In the above-layer epoxy-modified steel slag asphalt mixture, the QT-ER2 epoxy-modified asphalt is composed of base asphalt and QT-ER2 epoxy system. The QT-ER2 epoxy system is composed of E51 epoxy resin, amine curing agent and additives, and its dosage is 30%-35% of the mass of base asphalt; the gradation of the mixture is SMA-13 ​​or AC-13.

3. The high-performance layered modified full-structure steel slag asphalt pavement according to claim 2, characterized in that: The technical specifications of the QT-ER2 epoxy modified asphalt meet the following requirements: tensile strength at 23℃ ≥ 1.5MPa, elongation at break ≥ 180%, and construction allowance time ≥ 180min; the technical specifications of the top layer epoxy modified steel slag asphalt mixture meet the following requirements: dynamic stability at 60℃ ≥ 50,000 cycles / mm, low-temperature flexural strain at -10℃ ≥ 3,000με, and skid resistance attenuation rate ≤ 15.2% after 600,000 cycles.

4. The high-performance layered modified full-structure steel slag asphalt pavement according to claim 1, characterized in that: In the intermediate layer high-viscosity toughened modified steel slag asphalt mixture, the QT-HM3 high-viscosity toughened modified asphalt is composed of base asphalt and QT-HM3 composite modifier. The QT-HM3 composite modifier is a compound of SBS modifier and desulfurized rubber particles, and its dosage is not less than 5% of the mass of base asphalt; the gradation of the mixture is AC-20.

5. A high-performance layered modified full-structure steel slag asphalt pavement according to claim 4, characterized in that: The technical specifications of the QT-HM3 high-viscosity toughened modified asphalt meet the following requirements: penetration at 25℃ 40-60 (0.1mm), softening point ≥80℃, and dynamic viscosity at 60℃ ≥100,000 Pa·s; the technical specifications of the intermediate layer high-viscosity toughened modified steel slag asphalt mixture meet the following requirements: dynamic stability at 70℃ ≥3000 times / mm, and freeze-thaw splitting strength ratio ≥90%.

6. The high-performance layered modified full-structure steel slag asphalt pavement according to claim 1, characterized in that: In the lower layer composite reinforced modified steel slag asphalt mixture, the QT-M30 composite reinforced modified asphalt is composed of base asphalt and QT-M30 composite modifier. The QT-M30 composite modifier is mainly composed of linearized active waste rubber that has undergone desulfurization treatment, and its dosage is not less than 4.5% of the mass of the base asphalt. The gradation of the mixture is AC-25.

7. A high-performance layered modified full-structure steel slag asphalt pavement according to claim 6, characterized in that: The technical specifications of the QT-M30 composite reinforced modified asphalt meet the following requirements: penetration at 25℃ 40-80 (0.1mm), ductility at 5℃ ≥30cm, and softening point ≥70℃; the technical specifications of the lower layer composite reinforced modified steel slag asphalt mixture meet the following requirements: low temperature flexural strain at -10℃ ≥3000με, and freeze-thaw splitting strength ratio ≥90%.

8. A construction method for a high-performance layered modified full-structure steel slag asphalt pavement as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Raw material preparation and inspection: The steel slag aggregate is aged to ensure that the free calcium oxide (f-CaO) content meets the specifications; QT-ER2 epoxy system, QT-HM3 composite modifier, and QT-M30 composite modifier are prepared or procured respectively. S2: Preparation of modified asphalt: S2a: At the mixing plant, QT-HM3 composite modifier is mixed with base asphalt heated to 175-185℃ using a high-speed shearing process to prepare QT-HM3 high-viscosity toughened modified asphalt for the intermediate surface layer; S2b: At the mixing plant, the QT-M30 composite modifier is mixed with the base asphalt heated to 170-180℃ using a mixing and development process to prepare the QT-M30 composite reinforced modified asphalt for the lower layer. S3: Mixing of the mixture: S3a: Mixing of the lower layer aggregate: Heat the lower layer aggregate (steel slag content ≥80%) to 185-190℃ and mix it with the QT-M30 composite reinforced modified asphalt prepared in S2b at 180-185℃; S3b: Mixing of intermediate surface course aggregate: Heat the intermediate surface course aggregate (steel slag content ≥80%) to 190-195℃ and mix it with the QT-HM3 high viscosity toughened modified asphalt prepared in S2a at 185-190℃; S3c: Top layer mixture mixing: The synchronous spraying and mixing process is adopted. The top layer aggregate (100% steel slag content) is heated to 190-195℃, first dry-mixed with the base asphalt heated to 150-160℃, and then wet-mixed with the pre-mixed QT-ER2 epoxy system. The discharge temperature is controlled at 170-185℃. S4: Mixture transportation and paving: Transport vehicles shall be covered and insulated throughout the entire process; the paving temperature of the lower and middle layers shall not be lower than 165℃, and the paving temperature of the upper layer shall not be lower than 150℃; S5: Roll forming: S5a: Sub-layer compaction: Compaction is carried out using a combination of heavy-duty pneumatic roller and double-drum vibratory roller, with an initial compaction temperature of not less than 160℃. S5b: Intermediate surface layer compaction: Compaction is carried out using a double-drum vibratory roller, with an initial compaction temperature of not less than 165℃; S5c: Top layer compaction: A double-drum vibratory roller is used for close-following, slow-speed, high-frequency, low-amplitude compaction. The initial compaction temperature is not lower than 145℃, and the final compaction temperature is not lower than 90℃.

9. The construction method according to claim 8, characterized in that: In step S1, the aging time of the steel slag aggregate shall not be less than 6 months.

10. The construction method according to claim 8, characterized in that: In step S3c, from the start of mixing the QT-ER2 epoxy system with asphalt to the completion of mixing and discharge, the total time is strictly controlled within the residence time of the epoxy system of 180 minutes.

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