A composite asphalt pavement structure with all steel slag

Abstract

This invention belongs to the technical field of road paving, specifically relating to a fully steel slag composite asphalt pavement structure. This fully steel slag composite asphalt pavement structure is located on the roadbed and, from bottom to top, consists of a roadbed improvement layer, a composite base layer, and an asphalt surface layer. The roadbed improvement layer is a fully steel slag aggregate improvement layer; the composite base layer, from bottom to top, consists of a semi-rigid base layer containing fine steel slag aggregate and a flexible base layer containing large-diameter steel slag aggregate; the asphalt surface layer, from bottom to top, consists of a medium-to-high steel slag content asphalt mixture lower layer and a high steel slag content anti-skid and abrasion-resistant surface layer. The pavement structure of this invention is completely different from traditional asphalt pavements. Through the differentiated application of steel slag content and specifications in different structural layers, the coarse and fine steel slag aggregates are fully utilized, not only increasing the utilization rate of steel slag but also saving on the application of road construction materials such as sand and gravel aggregates, resulting in significant economic and social benefits; moreover, the resulting asphalt pavement has a long service life.

Description

Technical Field

[0001] This invention belongs to the technical field of road paving, specifically relating to a fully steel slag composite asphalt pavement structure. Background Technology

[0002] Highways are a vital infrastructure for national economic and social development. As a crucial component of the national economy, they play a significant role in both promoting and constraining economic growth. Over 90% of my country's high-grade highways use asphalt pavements with semi-rigid base courses. However, highway and other infrastructure construction faces a shortage of high-quality aggregates. On the one hand, semi-rigid base courses are thick, requiring substantial amounts of sand, gravel, and other road construction materials for their construction. In my country alone, asphalt pavement construction consumes 250 million tons of high-quality sand and gravel annually (enough to form a 1m cross-section). 2 The wall (which could circle the Earth's equator 2.8 times) has a huge negative impact on the environment, leading to the destruction of mountains and other ecological environments. At the same time, in areas where high-quality stone resources are scarce, it is often necessary to transport them from other places over long distances or even across regions to ensure the quality of the road surface, resulting in huge transportation pressure and energy consumption, and huge costs. On the other hand, the shrinkage cracking of semi-rigid base courses and the resulting reflective cracks in asphalt pavements are common, causing early damage to the road structure. Periodic major repairs and reconstructions also cause huge waste of resources and financial and environmental pressures.

[0003] Steel slag is the largest solid waste generated in the steel industry, accounting for approximately 15% of crude steel production. Steel slag aggregate possesses advantages such as high strength, strong wear resistance, and good asphalt adsorption, exhibiting excellent road performance after treatment, making it a good alternative to sand and gravel aggregates for road construction. However, the application rate of steel slag in road surfaces is only 10% of its production, leaving a large portion unutilized. The main reasons for this are as follows: First, steel slag differs from ordinary aggregates in characteristics. It contains unstable components such as free calcium oxide, which easily swells upon contact with water. Traditional methods of directly replacing aggregates pose a potential risk of road surface damage.

[0004] Secondly, existing technologies use relatively small amounts of steel slag when adding steel slag to the mixture, with stone still making up a large proportion of the mixture. Furthermore, existing steel slag mixtures cannot be applied to the entire system (the entire structure of asphalt pavement). When steel slag is added, the pavement is prone to mushroom cloud-like cracking. The root cause lies in the problem of the amount of steel slag added and the mismatch of the steel slag aggregate ratio.

[0005] Third, the aggregate specifications for asphalt pavement mixtures are high, and traditional application methods have a low application rate of steel slag aggregates. It is impossible to achieve full application of coarse and fine aggregates in the entire structure of asphalt pavement, which increases the application cost of steel slag and causes great waste. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned deficiencies by providing a fully integrated steel slag composite asphalt pavement structure. Compared with existing technologies, the pavement structure of this invention is completely different from traditional asphalt pavements. Through the differentiated application of steel slag content and specifications in different structural layers, coarse and fine steel slag aggregates are applied throughout the entire pavement. That is, the entire structure of the asphalt pavement from top to bottom is a mixture structure containing steel slag aggregates. This not only improves the utilization rate of steel slag and saves on the application of road construction materials such as sand and gravel aggregates, resulting in significant economic and social benefits, but also provides a longer service life. The service life of traditional asphalt pavement structures is generally 12-15 years, while the service life of the fully integrated steel slag composite asphalt pavement structure described in this invention can reach 20-25 years.

[0007] The specific technical solution of the present invention is as follows:

[0008] A composite asphalt pavement structure consisting entirely of steel slag is located on the roadbed, and from bottom to top consists of a roadbed improvement layer, a composite base layer, and an asphalt surface layer.

[0009] The subgrade improvement layer is an all-steel slag granular material improvement layer;

[0010] The composite base layer consists of a semi-rigid base layer containing fine steel slag aggregate and a flexible base layer containing large-diameter steel slag aggregate, from bottom to top.

[0011] The asphalt surface layer consists of, from bottom to top, a medium-to-high steel slag asphalt mixture lower layer and a high steel slag anti-skid and wear-resistant surface layer.

[0012] The improved layer of all-steel slag aggregate is made by mixing and compacting 100% steel slag aggregate with water.

[0013] In the semi-rigid base layer containing fine steel slag aggregate, the aggregate with a sieve opening of less than 4.75 mm is steel slag aggregate, and the aggregate with a sieve opening of more than 4.75 mm is stone; the binder is cement.

[0014] In the flexible base layer containing large-diameter steel slag aggregate, the aggregate with a sieve opening of 19 mm or larger is steel slag aggregate, and the aggregate with a sieve opening of less than 19 mm is limestone, manufactured sand and mineral powder; the binder is asphalt.

[0015] The 4.75-19mm aggregate in the lower layer of the asphalt mixture with medium to high steel slag content is a composite of steel slag aggregate and limestone aggregate or 100% steel slag aggregate. When the 4.75-19mm aggregate is a mixture of steel slag aggregate and limestone aggregate, the steel slag aggregate content in the 4.75-19mm aggregate is ≤70% of the total aggregate of the lower layer of the asphalt mixture; the binder is asphalt.

[0016] The high steel slag content anti-slip wear surface layer contains steel slag aggregate with aggregates larger than 4.75mm and limestone and mineral powder with aggregates smaller than 4.75mm; the binder is asphalt and the additive is lignin fiber.

[0017] In this invention, each layer of the all-steel slag composite asphalt pavement structure is specifically as follows:

[0018] The specific composition of the steel slag aggregate in the all-steel slag granular material improvement layer is as follows: by mass ratio, the ratio of steel slag aggregate with a particle size of 20-30mm: 10-20mm: 5-10mm: 0-5mm is 12-18: 27-33: 20-26: 29-35.

[0019] The specific aggregate composition of the semi-rigid base course containing fine steel slag aggregate is as follows: by mass ratio, 20-25mm stone: 10-20mm stone: 5-10mm stone: 3-5mm steel slag aggregate: 0-3mm steel slag aggregate is 22-28: 25-31: 18-24: 6-12: 14-20.

[0020] Preferably, the stone material is one or more of limestone aggregate, granite aggregate, amphibolite aggregate, or urban construction waste material.

[0021] The moisture content of the aggregate in the semi-rigid base course containing fine steel slag is 4.8-5.2%.

[0022] The aggregate composition of the flexible base course containing large-diameter steel slag aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm limestone: 0-5mm limestone manufactured sand: mineral powder is 41-47: 1-6: 10-16: 8-14: 24-30: 1-5.

[0023] The asphalt binder in the flexible base course containing large-diameter steel slag aggregate is SBS modified petroleum asphalt; the amount of SBS modified petroleum asphalt used is 3.2-3.8 wt%.

[0024] The specific aggregate composition of the lower layer of the asphalt mixture with medium to high steel slag content is as follows: by mass ratio, 10-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm steel slag aggregate: 0-5mm limestone manufactured sand: mineral powder is 13-19: 28-34: 20-26: 24-30: 1-6. The lower layer is the key load-bearing layer above the base course, and the 4.75-19 aggregate is the most important aggregate, which is also the range of aggregates with good performance requirements for the skeleton. However, the traditional use of limestone for this grade of aggregate has poor resistance to rutting and durability. The aggregate ratio of this layer described in this invention can effectively enhance its resistance to rutting and durability.

[0025] The asphalt binder in the lower layer of the asphalt mixture with medium to high steel slag content is SBS modified petroleum asphalt; the asphalt content is 3.9-4.5 wt%.

[0026] The aggregate composition of the anti-slip wear surface layer with high steel slag content is as follows: by mass ratio, 10-15mm steel slag aggregate: 5-10mm steel slag aggregate: 0-3mm limestone: mineral powder = 35-41: 33-40: 12-18: 7-13.

[0027] The asphalt binder in the aggregate of the high steel slag content anti-skid wear surface layer is high viscoelastic modified petroleum asphalt; the asphalt content is 5.6-6.2 wt%; and the lignin fiber content is 0.3-0.36 wt%.

[0028] The steel slag aggregate has a moisture content of 4.0%-4.5%; the free calcium oxide content of the steel slag aggregate is ≤3%, and the water immersion expansion rate is ≤1.8%.

[0029] Furthermore, the specific layers of the entire steel slag composite asphalt pavement structure are as follows:

[0030] The specific composition of the steel slag aggregate in the all-steel slag granular material improvement layer is as follows: by mass ratio, the ratio of steel slag aggregate with particle size of 20-30mm: steel slag aggregate with particle size of 10-20mm: steel slag aggregate with particle size of 5-10mm: steel slag aggregate with particle size of 0-5mm is 15:30:23:32.

[0031] The aggregate composition of the semi-rigid base course containing fine steel slag is as follows: by mass ratio, 20-25mm stone: 10-20mm stone: 5-10mm stone: 3-5mm steel slag: 0-3mm steel slag = 25:28:21:9:17.

[0032] The semi-rigid base course containing fine steel slag aggregate has a moisture content of 5.1% and a maximum dry density of 2.374 g / cm³. 3 .

[0033] The aggregate composition of the flexible base layer containing large-diameter steel slag aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm limestone: 0-5mm limestone manufactured sand: mineral powder = 44:3:13:11:27:2.

[0034] The amount of SBS modified petroleum asphalt binder in the flexible base course containing large-diameter steel slag aggregate is 3.5 wt%.

[0035] The specific composition of the aggregate in the lower layer of the asphalt mixture with medium and high steel slag content is as follows: by mass ratio, 10-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm steel slag aggregate: 0-5mm limestone manufactured sand: mineral powder = 16:31:23:27:3.

[0036] The amount of SBS-modified petroleum asphalt binder in the lower layer of the asphalt mixture with medium and high steel slag content is 4.2%.

[0037] The aggregate composition of the anti-slip and wear-resistant surface layer with high steel slag content is as follows: by mass ratio, 10-15mm steel slag aggregate: 5-10mm steel slag aggregate: 0-3mm limestone: mineral powder = 38:37:15:10.

[0038] The amount of high-viscoelastic modified petroleum asphalt binder in the aggregate of the high-steel slag content anti-skid wear surface layer is 5.9 wt%; the amount of lignin fiber is 0.33 wt%.

[0039] The steel slag aggregate has a moisture content of 4.3% and a maximum dry density of 2.261 g / cm³. 3 .

[0040] In this invention, the gradation range of the all-steel slag aggregate improvement layer in the all-steel slag composite asphalt pavement structure is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 90-100% passing rate for a standard sieve with a 31.5mm aperture; 64-84% passing rate for a standard sieve with a 19mm aperture; 40-59% passing rate for a standard sieve with a 9.5mm aperture; 24-42% passing rate for a standard sieve with a 4.75mm aperture; 14-30% passing rate for a standard sieve with a 2.36mm aperture; 6-17% passing rate for a standard sieve with a 0.6mm aperture; and 0-7% passing rate for a standard sieve with a 0.075mm aperture.

[0041] In this invention, the gradation range of the semi-rigid base course containing fine steel slag aggregate in the fully steel slag composite asphalt pavement structure is as follows: 100% passing rate for a standard sieve with a 31.5mm aperture; 92-100% passing rate for a standard sieve with a 26.5mm aperture; 80-86% passing rate for a standard sieve with a 19mm aperture; 45-55% passing rate for a standard sieve with a 9.5mm aperture; 28-36% passing rate for a standard sieve with a 4.75mm aperture; 18-26% passing rate for a standard sieve with a 2.36mm aperture; 10-16% passing rate for a standard sieve with a 0.6mm aperture; and 2-5% passing rate for a standard sieve with a 0.075mm aperture.

[0042] In this invention, the gradation range of the flexible base course containing large-diameter steel slag aggregate in the fully composite asphalt pavement structure is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 90-100% passing rate for a standard sieve with a 31.5mm aperture; 70-95% passing rate for a standard sieve with a 26.5mm aperture; 40-76% passing rate for a standard sieve with a 19mm aperture; 28-58% passing rate for a standard sieve with a 13.2mm aperture; and [missing information - likely related to gradation range]. The passing rates are as follows: 19-39% for standard sieve apertures of 4.75mm, 6-29% for standard sieve apertures of 2.36mm, 6-18% for standard sieve apertures of 1.18mm, 3-15% for standard sieve apertures of 0.6mm, 2-10% for standard sieve apertures of 0.3mm, 1-7% for standard sieve apertures of 0.15mm, and 1-4% for standard sieve apertures of 0.075mm.

[0043] In this invention, the gradation range of the lower layer of the asphalt mixture with medium to high steel slag content in the all-steel slag composite asphalt pavement structure is as follows: 100% passing rate through a standard sieve with a 26.5mm aperture; 90-100% passing rate through a standard sieve with a 19mm aperture; 83-95% passing rate through a standard sieve with a 16mm aperture; 73-86% passing rate through a standard sieve with a 13.2mm aperture; 56-70% passing rate through a standard sieve with a 9.5mm aperture; 35-48% passing rate through a standard sieve with a 4.75mm aperture; 22-33% passing rate through a standard sieve with a 2.36mm aperture; 16-23% passing rate through a standard sieve with a 1.18mm aperture; 10-16% passing rate through a standard sieve with a 0.6mm aperture; 6-11% passing rate through a standard sieve with a 0.3mm aperture; 5-9% passing rate through a standard sieve with a 0.15mm aperture; and 4-6% passing rate through a standard sieve with a 0.075mm aperture.

[0044] In this invention, the gradation range of the high steel slag content anti-skid and wear-resistant surface layer of the all-steel slag composite asphalt pavement structure is as follows: 100% passing rate through a standard sieve with a 16mm aperture; 90-100% passing rate through a standard sieve with a 13.2mm aperture; 50-75% passing rate through a standard sieve with a 9.5mm aperture; 20-34% passing rate through a standard sieve with a 4.75mm aperture; 15-26% passing rate through a standard sieve with a 2.36mm aperture; 14-24% passing rate through a standard sieve with a 1.18mm aperture; 12-20% passing rate through a standard sieve with a 0.6mm aperture; 10-16% passing rate through a standard sieve with a 0.3mm aperture; 9-15% passing rate through a standard sieve with a 0.15mm aperture; and 8-12% passing rate through a standard sieve with a 0.075mm aperture.

[0045] In this invention, the thickness of the all-steel slag aggregate improvement layer in the all-steel slag composite asphalt pavement structure is 15-20cm, the thickness of the semi-rigid base layer containing fine steel slag aggregate is 50-60cm, the thickness of the flexible base layer containing large-diameter steel slag aggregate is 10-15cm, the thickness of the asphalt mixture lower layer with medium to high steel slag content is 12-16cm, and the thickness of the anti-skid and abrasion-resistant surface layer with high steel slag content is 4-6cm.

[0046] In this invention, the compaction degree of the all-steel slag aggregate improvement layer in the all-steel slag composite asphalt pavement structure is ≥96%; the compaction degree of the semi-rigid base layer containing fine steel slag aggregate is ≥97%; the porosity of the flexible base layer containing large-diameter steel slag aggregate is 15-20%; and the porosity of the asphalt mixture lower layer with medium to high steel slag content and the anti-skid wear surface layer with high steel slag content are both 2-3%.

[0047] The beneficial effects of this invention are as follows: Compared with the prior art, the all-steel slag composite asphalt pavement structure of this invention has the following advantages:

[0048] (1) By applying the different contents and specifications of steel slag in different structural layers, steel slag coarse and fine aggregates can be used in the whole system, which improves the utilization rate of steel slag. At present, the amount of steel slag is generally 20-30%, while the amount of steel slag in this invention is at least 70%, or even more than 90% of the total steel slag, which saves the application of road construction materials such as sand and gravel aggregates, resulting in huge economic and social benefits.

[0049] Taking a 309.2-kilometer-long four-lane expressway as an example, the steel slag composite asphalt pavement structure described in this invention can save approximately 26,800 yuan / (year·km·single lane) in construction and maintenance costs compared to the current traditional asphalt pavement. The total annual cost savings for the entire length is: 26,800 yuan / year·km × 309.2 kilometers × 4 lanes × 1 year = 33,146,240 yuan.

[0050] (2) By adding steel slag aggregate with advantages such as high strength, high wear resistance and strong adsorption to the mixture, and adding steel slag aggregate of specific specifications according to the function of each structural layer, and making targeted design for the steel slag aggregate mixture, the risk of damage to the pavement structure caused by the expansion of steel slag when it comes into contact with water is avoided, the pavement structure performance is improved, and the service life of the road is extended to 20-25 years.

[0051] (3) By incorporating fine steel slag aggregate with micro-expansion characteristics into semi-rigid materials, the occurrence of shrinkage cracks in semi-rigid materials is reduced, the durability of pavement structures is improved, and the financial and social pressure caused by pavement maintenance is reduced.

[0052] (4) By adding steel slag aggregate to the asphalt mixture, the rutting resistance of the asphalt mixture is improved, and the early damage to the road surface is effectively reduced.

[0053] (5) By incorporating steel slag aggregate into the asphalt mixture in the surface layer, the anti-skid and anti-wear properties of the asphalt pavement are improved, thus enhancing driving safety. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the all-steel slag composite asphalt pavement structure described in this invention.

[0055] Among them, 1 is the roadbed, 2 is the all-steel slag aggregate improvement layer, 3 is the semi-rigid base course containing fine steel slag aggregate, 4 is the flexible base course containing large-diameter steel slag aggregate, 5 is the asphalt mixture lower layer with medium and high steel slag content, and 6 is the anti-skid and wear-resistant surface layer with high steel slag content. Detailed Implementation

[0056] The combined base asphalt pavement structure of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] Example 1

[0058] The entire steel slag composite asphalt pavement structure is located on subgrade 1, and consists of, from bottom to top, a subgrade improvement layer, a composite base layer, and an asphalt surface layer. The subgrade improvement layer is a full steel slag aggregate improvement layer; the composite base layer consists of, from bottom to top, a semi-rigid base layer containing fine steel slag aggregate and a flexible base layer containing large-diameter steel slag aggregate; the asphalt surface layer consists of, from bottom to top, a medium-to-high steel slag content asphalt mixture lower layer and a high steel slag content anti-skid and abrasion-resistant surface layer.

[0059] The following combination Figure 1 The structure of each layer is explained in detail from bottom to top:

[0060] The all-steel slag aggregate improvement layer 2 is made by mixing and compacting 100% steel slag aggregate with water. The specific composition of the steel slag aggregate is as follows: by mass ratio, the ratio of steel slag aggregate with a particle size of 20-30mm: 10-20mm: 5-10mm: 0-5mm is 15:30:23:32.

[0061] The gradation range of the all-steel slag aggregate improvement layer is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 99% passing rate for a standard sieve with a 31.5mm aperture; 82% passing rate for a standard sieve with a 19mm aperture; 49.2% passing rate for a standard sieve with a 9.5mm aperture; 32.2% passing rate for a standard sieve with a 4.75mm aperture; 24.5% passing rate for a standard sieve with a 2.36mm aperture; 12.3% passing rate for a standard sieve with a 0.6mm aperture; and 4.6% passing rate for a standard sieve with a 0.075mm aperture.

[0062]

[0063]

[0064] In the semi-rigid base course 3 containing fine steel slag aggregate, the aggregate with a sieve opening smaller than 4.75 mm is steel slag aggregate, and the aggregate with a sieve opening larger than 4.75 mm is limestone aggregate; the binder is cement. The moisture content of the aggregate is 5.1%, and the maximum dry density is 2.374 g / cm³. 3 The aggregate composition is as follows: by mass ratio, 20-25mm limestone: 10-20mm limestone: 5-10mm limestone: 3-5mm steel slag: 0-3mm steel slag = 25:28:21:9:17.

[0065] The gradation range of the semi-rigid base course containing fine steel slag aggregate is as follows: 100% passing rate for a standard sieve with a sieve aperture of 31.5 mm; 96.3% passing rate for a standard sieve aperture of 26.5 mm; 82.4% passing rate for a standard sieve aperture of 19 mm; 50.5% passing rate for a standard sieve aperture of 9.5 mm; 30.6% passing rate for a standard sieve aperture of 4.75 mm; 21.2% passing rate for a standard sieve aperture of 2.36 mm; 11.5% passing rate for a standard sieve aperture of 0.6 mm; and 2.5% passing rate for a standard sieve aperture of 0.075 mm.

[0066] The flexible base course 4 containing large-diameter steel slag aggregate uses steel slag aggregate with sieve openings larger than 19mm, and limestone manufactured sand and mineral powder with sieve openings smaller than 19mm. The binder is SBS modified petroleum asphalt, with a dosage of 3.5wt%. The specific composition of the aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm limestone : 0-5mm limestone manufactured sand : mineral powder = 44 : 3 : 13 : 11 : 27 : 2.

[0067] The gradation ranges for flexible base courses containing large-diameter steel slag aggregates are as follows: 100% passing rate for standard sieve apertures of 37.5mm; 100% passing rate for standard sieve apertures of 31.5mm; 94.3% passing rate for standard sieve apertures of 26.5mm; 61.7% passing rate for standard sieve apertures of 19mm; 41.7% passing rate for standard sieve apertures of 13.2mm; 30.5% passing rate for standard sieve apertures of 9.5mm; 14.9% passing rate for standard sieve apertures of 4.75mm; 11.2% passing rate for standard sieve apertures of 2.36mm; 8.4% passing rate for standard sieve apertures of 1.18mm; 5.8% passing rate for standard sieve apertures of 0.6mm; 4.1% passing rate for standard sieve apertures of 0.3mm; 3.2% passing rate for standard sieve apertures of 0.15mm; and 2.3% passing rate for standard sieve apertures of 0.075mm.

[0068] The 4.75-19mm aggregate in the lower layer 5 of the medium-high steel slag asphalt mixture is a composite of steel slag aggregate and limestone aggregate. The binder is SBS modified petroleum asphalt, with a dosage of 4.2wt%. The specific composition of the aggregate is as follows: by mass ratio, 10-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm steel slag aggregate : 0-5mm limestone manufactured sand : mineral powder = 16 : 31 : 23 : 27 : 3.

[0069] The gradation ranges for the lower layer of asphalt mixtures with medium to high steel slag content are as follows: 100% passing rate for a standard sieve with a 26.5mm aperture; 97.9% passing rate for a standard sieve with a 19mm aperture; 85.2% passing rate for a standard sieve with a 16mm aperture; 79.4% passing rate for a standard sieve with a 13.2mm aperture; 61.5% passing rate for a standard sieve with a 9.5mm aperture; 40.8% passing rate for a standard sieve with a 4.75mm aperture; 25.1% passing rate for a standard sieve with a 2.36mm aperture; 19.6% passing rate for a standard sieve with a 1.18mm aperture; 13.4% passing rate for a standard sieve with a 0.6mm aperture; 7.6% passing rate for a standard sieve with a 0.3mm aperture; 6.3% passing rate for a standard sieve with a 0.15mm aperture; and 5% passing rate for a standard sieve with a 0.075mm aperture.

[0070] The high steel slag content anti-slip wear surface layer 6 contains steel slag aggregate with a thickness of 4.75mm or more, and limestone and mineral powder with a thickness of less than 4.75mm. The binder is high viscoelastic modified petroleum asphalt, and the additive is lignin fiber. The asphalt binder content is 5.9wt%, and the lignin fiber content is 0.33wt%. The specific composition of the aggregate is as follows: by mass ratio, 10-15mm steel slag aggregate : 5-10mm steel slag aggregate : 0-3mm limestone : mineral powder = 38 : 37 : 15 : 10.

[0071] The gradation range of the anti-slip wear surface layer with high steel slag content is as follows: 100% passing rate for a standard sieve aperture of 16mm; 95.2% passing rate for a standard sieve aperture of 13.2mm; 60.6% passing rate for a standard sieve aperture of 9.5mm; 30.4% passing rate for a standard sieve aperture of 4.75mm; 22.3% passing rate for a standard sieve aperture of 2.36mm; 19.8% passing rate for a standard sieve aperture of 1.18mm; 17.9% passing rate for a standard sieve aperture of 0.6mm; 15.1% passing rate for a standard sieve aperture of 0.3mm; 12.9% passing rate for a standard sieve aperture of 0.15mm; and 11.2% passing rate for a standard sieve aperture of 0.075mm.

[0072] The moisture content of the above-mentioned steel slag aggregate is 4.3%; the maximum dry density is 2.261 g / cm³. 3The free calcium oxide content of the steel slag aggregate is 1.78%, and the water immersion swelling rate is 1.12%.

[0073] In this embodiment, the thickness of the all-steel slag composite asphalt pavement structure is 15cm for the all-steel slag aggregate improvement layer, 50cm for the semi-rigid base layer containing fine steel slag aggregate, 12cm for the flexible base layer containing large-diameter steel slag aggregate, 12cm for the asphalt mixture lower layer with medium to high steel slag content, and 4cm for the anti-skid and abrasion-resistant surface layer with high steel slag content.

[0074] In this embodiment, the compaction degree of the all-steel slag composite asphalt pavement structure is 97% for the all-steel slag aggregate improvement layer; the compaction degree of the semi-rigid base course containing fine steel slag aggregate is 98%; the porosity of the flexible base course containing large-diameter steel slag aggregate is 16%; and the porosity of the asphalt mixture lower layer with medium to high steel slag content and the anti-skid wear surface layer with high steel slag content are both 2.5%.

[0075] The pavement performance of the all-steel slag composite asphalt pavement structure described in this embodiment will be tested below.

[0076] 1. Calculation of the overall structural performance of the road surface

[0077] Preliminary traffic surveys and analyses of the test section indicate that the daily traffic volume of large passenger vehicles and freight trucks is 1950 vehicles / day. The average annual growth rate of traffic volume within the design service life is 6.5%, with a directional coefficient of 0.55 and a lane coefficient of 1.0. The cumulative traffic volume of large passenger vehicles and freight trucks in the design lanes within the design service life is:

[0078]

[0079] Therefore, the design traffic load level is medium.

[0080] With 30% of trucks being full-truckloads and 55% being semi-trailer trucks, the highway TTC classification is determined to be TTC1 according to Table A.2.6-1 of the "Specifications for Design of Asphalt Pavement of Highways" (JTG D50-2017). Then, the vehicle type distribution coefficient is determined according to Table A.2.6-2, as shown in Table 1.

[0081] Table 1 Vehicle Type Distribution Coefficient

[0082]

[0083] The ratio of unloaded vehicles to fully loaded vehicles should be selected according to Table A.3.3-2 of the "Specifications for Design of Asphalt Pavement of Highways" as shown in Table 2.

[0084] Table 2. Proportion of partially loaded and fully loaded vehicles

[0085] Vehicle type Category 2 3 categories 4 categories 5 categories 6 categories 7 categories 8 categories 9 categories 10 categories 11 categories Non-fully loaded vehicle ratio 0.85 0.9 0.65 0.75 0.55 0.7 0.45 0.6 0.55 0.65 Fully loaded vehicle ratio 0.15 0.1 0.35 0.25 0.45 0.3 0.55 0.4 0.45 0.35

[0086] The design parameters for asphalt pavement structure verification include the permanent deformation of the asphalt mixture layer, the tensile stress at the bottom of the inorganic binder stabilized layer, the low-temperature cracking index of the asphalt surface layer, and the antifreeze thickness verification. Based on the two parameters of permanent deformation of the asphalt mixture layer and tensile stress at the bottom of the inorganic binder stabilized layer, the equivalent design axle load conversion factors for each vehicle type (non-fully loaded and fully loaded) are obtained, as shown in Table 3.

[0087] Table 3 Equivalent Design Axle Load Conversion Factors for Non-Fully Loaded and Fully Loaded Vehicles

[0088]

[0089]

[0090] (1) When the tensile stress at the bottom of the inorganic binder stabilized layer is determined as the design index, the initial annual design lane daily average equivalent week number N1 is shown in Table 4.

[0091] Table 4. Initial Year Design Lane Daily Average Equivalent Axle Times N1 (times)

[0092]

[0093]

[0094] Then the cumulative number of times the equivalent design axle load of the design lane is applied is N. e2 for:

[0095]

[0096] (2) When the permanent deformation of the asphalt mixture layer is used as the design index, the average daily equivalent axle number N1 of the initial annual design lane (the period from the opening to the first maintenance for ruts is 8 years) is determined, and the results are shown in Table 5.

[0097] Table 5. Initial Year Design Lane Daily Average Equivalent Axle Times N1 (times)

[0098]

[0099]

[0100] Then the cumulative number of times the equivalent design axle load of the design lane is applied is N. e3 for:

[0101]

[0102] 2. Preliminary pavement structure scheme

[0103] Based on the design traffic load level, the pavement structure is shown in Table 6.

[0104] Table 6. Proposed Asphalt Pavement Structure (i.e., the structure described in this embodiment)

[0105]

[0106] 3. Material parameters of roadbed and structural layers

[0107] (1) Resilient modulus of the top surface of the roadbed

[0108] The resilient modulus of the top surface of the subgrade, after humidity adjustment and reduction by wet-dry or freeze-thaw cycles, is E0 = 52 MPa, which is greater than 40 MPa and meets the requirements of 5.2.2 of the "Specifications for Design of Highway Asphalt Pavement".

[0109] (2) Flexural strength and elastic modulus of base layer and granular layer materials

[0110] The elastic modulus of inorganic binder stabilized materials is determined by multiplying it by the structural layer modulus adjustment factor of 0.5. The specific calculation results are shown in Table 7.

[0111] Table 7. Flexural strength and elastic modulus of base and improvement layer materials

[0112] Material Name Flexural tensile strength (MPa) Compressive resilient modulus (MPa) Semi-rigid base course containing fine steel slag aggregate 1.2 8000 All-steel slag granular material improvement layer 0.5 2000

[0113] (3) Modulus of asphalt surface layer and flexible base layer

[0114] The dynamic compression modulus of asphalt mixtures was selected according to the recommended range in Table 5.5.11 of the "Specifications for Design of Asphalt Pavement on Highways". The test temperature was 20℃ and the loading frequency was 10Hz. The specific values ​​are shown in Table 8.

[0115] Table 8 Dynamic Compression Modulus of Asphalt Mixtures at 20℃

[0116] Asphalt mixture types Dynamic compressive modulus (MPa) Anti-slip wear surface layer with high steel slag content 12000 Medium-to-high steel slag content asphalt mixture lower layer 15000 Flexible base course containing large-diameter steel slag aggregate 20000

[0117] Note: Modified asphalt is selected as the type of asphalt.

[0118] (4) Poisson's ratio

[0119] The Poisson's ratio of various materials should be selected according to Table 5.5.11 of the "Specifications for Design of Highway Asphalt Pavement", as shown in Table 9.

[0120] Table 9 Poisson's Ratio

[0121]

[0122] 4. Structural verification

[0123] According to Table 6.2.1 of the "Specifications for Design of Highway Asphalt Pavement", the design parameters that need to be verified for this pavement structure combination are the tensile stress at the bottom of the inorganic binder stabilized layer and the permanent deformation of the asphalt mixture layer.

[0124] (1) Fatigue cracking calculation of semi-rigid base layer

[0125] The fatigue cracking life of the base course should be calculated based on the tensile stress at the bottom of each all-steel slag aggregate improved layer obtained from the pavement structure analysis, using the following formula.

[0126]

[0127] According to Table B.1.1 of the "Specifications for Design of Asphalt Pavement on Highways", the regional adjustment factor K for the test section is interpolated. α Take 0.65.

[0128] Based on the location of the test section, the temperature adjustment coefficient of the reference pavement structure was obtained from Table G.1.2 of the "Specifications for Design of Highway Asphalt Pavement".

[0129] Based on the preliminary pavement structure and structural layer material parameters, according to the formula... Calculate the temperature adjustment coefficient K of the pavement structure T2 .

[0130] K T2 = 0.874 × 1.155 × 0.77 1+(-0.209)+0.126 =0.794.

[0131] According to Table B.2.1-1 of the "Specifications for Design of Asphalt Pavement of Highway", the fatigue failure model parameters are a = 13.24 and b = 12.52.

[0132] Based on the structural layer thickness and mechanical parameters, the tensile stress at the bottom of the semi-rigid base layer was calculated using the theory of elastic layered systems, and is listed in Table 10.

[0133] Table 10 Calculation results of tensile stress at the bottom of semi-rigid base layer

[0134] Base layer (cm) Tensile stress (MPa) 50 0.209

[0135] The fatigue crack life of semi-rigid base layers is calculated and listed in Table 11.

[0136] Table 11 Fatigue Cracking Life of Semi-rigid Substrates

[0137]

[0138] (2) Fatigue cracking calculation of semi-rigid base layer

[0139] Based on the structural layer thickness and mechanical parameters, and using the elastic layered system theory, the fatigue crack life of the base layer is less than the cumulative number of times the equivalent design axle load of the design lane is applied, thus failing to meet the design requirements. The base layer thickness is increased in increments of 20mm. When the base layer thickness reaches 400mm, the fatigue crack life of the base layer exceeds the cumulative number of times the equivalent design axle load of the design lane is applied, thus meeting the design requirements. The structural details are shown in Table 12.

[0140] Table 12 Fatigue Cracking Life of Semi-rigid Substrates

[0141]

[0142] (3) Dynamic stability of asphalt mixture layer

[0143] The test temperature was 70℃, the wheel rolling pressure was 1.0MPa, and the dynamic stability of the asphalt mixture rutting is shown in Table 13.

[0144] Table 13 Dynamic stability of asphalt mixture rutting test

[0145] Material type Dynamic stability (cycles / mm) Anti-slip wear surface layer with high steel slag content 4986 Medium-to-high steel slag content asphalt mixture lower layer 3524 Flexible base course containing large-diameter steel slag aggregate 2860

[0146] (4) Low-temperature cracking index of road surface

[0147] The low-temperature cracking index (CI) of asphalt pavement is calculated using the following formula.

[0148] CI = 1.95 × 10 -3 s t lg b-0.075(T+0.07H a )lg S t +0.15.

[0149] In this embodiment, the test road's low-temperature design temperature T was -40℃; the roadbed filler was low-liquid-limit clay, and the roadbed type parameter b = 2; the stiffness modulus S of the surface layer modified asphalt was measured in the bending beam rheological test at -30℃. t The pressure is 130 MPa; the thickness of the asphalt mixture layer is h. a =160mm. Substituting the determined parameters into the above formula, the low-temperature cracking index CI of the asphalt pavement is calculated to be 2, which meets the requirements for the low-temperature cracking index in Table 3.0.6-2 of the specification.

[0150] Example 2

[0151] The all-steel slag aggregate improvement layer 2 is made by mixing and compacting 100% steel slag aggregate with water. The specific composition of the steel slag aggregate is as follows: by mass ratio, the ratio of steel slag aggregate with a particle size of 20-30mm: 10-20mm: 5-10mm: 0-5mm is 12:27:20:29.

[0152] The gradation range of the all-steel slag aggregate improvement layer is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 98.2% passing rate for a standard sieve with a 31.5mm aperture; 73.4% passing rate for a standard sieve with a 19mm aperture; 51.8% passing rate for a standard sieve with a 9.5mm aperture; 33.5% passing rate for a standard sieve with a 4.75mm aperture; 16.1% passing rate for a standard sieve with a 2.36mm aperture; 8.2% passing rate for a standard sieve with a 0.6mm aperture; and 3.5% passing rate for a standard sieve with a 0.075mm aperture.

[0153] In the semi-rigid base course 3 containing fine steel slag aggregate, the aggregate with a sieve opening smaller than 4.75 mm is steel slag aggregate, and the aggregate with a sieve opening larger than 4.75 mm is limestone aggregate; the binder is cement. The moisture content of the aggregate is 4.8%, and the maximum dry density is 2.374 g / cm³. 3 The aggregate composition is as follows: by mass ratio, 20-25mm stone: 10-20mm stone: 5-10mm stone: 3-5mm steel slag: 0-3mm steel slag = 22:25:18:6:14.

[0154] The gradation range of the semi-rigid base course containing fine steel slag aggregate is as follows: 100% passing rate for a standard sieve with a sieve aperture of 31.5 mm; 99.1% passing rate for a standard sieve aperture of 26.5 mm; 81.6% passing rate for a standard sieve aperture of 19 mm; 50.3% passing rate for a standard sieve aperture of 9.5 mm; 31.9% passing rate for a standard sieve aperture of 4.75 mm; 21.5% passing rate for a standard sieve aperture of 2.36 mm; 11.3% passing rate for a standard sieve aperture of 0.6 mm; and 3% passing rate for a standard sieve aperture of 0.075 mm.

[0155] The flexible base course 4 containing large-diameter steel slag aggregate uses steel slag aggregate with sieve openings larger than 19mm, and limestone manufactured sand and mineral powder with sieve openings smaller than 19mm. The binder is SBS modified petroleum asphalt, with a dosage of 3.5wt%. The specific composition of the aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm limestone : 0-5mm limestone manufactured sand : mineral powder = 41 : 6 : 10 : 8 : 30 : 1.

[0156] The gradation ranges for flexible base courses containing large-diameter steel slag aggregate are as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 96.8% passing rate for a standard sieve with a 31.5mm aperture; 86.5% passing rate for a standard sieve with a 26.5mm aperture; 62.8% passing rate for a standard sieve with a 19mm aperture; 41.2% passing rate for a standard sieve with a 13.2mm aperture; 32.4% passing rate for a standard sieve with a 9.5mm aperture; 23.5% passing rate for a standard sieve with a 4.75mm aperture; 12.2% passing rate for a standard sieve with a 2.36mm aperture; 8.5% passing rate for a standard sieve with a 1.18mm aperture; 4.2% passing rate for a standard sieve with a 0.6mm aperture; 4.1% passing rate for a standard sieve with a 0.3mm aperture; 3.4% passing rate for a standard sieve with a 0.15mm aperture; and 2.3% passing rate for a standard sieve with a 0.075mm aperture.

[0157] The 4.75-19mm aggregate in the lower layer 5 of the medium-high steel slag asphalt mixture is a composite of steel slag aggregate and limestone aggregate. The binder is SBS modified petroleum asphalt, with a dosage of 4.2wt%. The specific composition of the aggregate is as follows: by mass ratio, 10-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm steel slag aggregate : 0-5mm limestone manufactured sand : mineral powder = 13 : 28 : 26 : 24 : 6.

[0158] The gradation ranges for the lower layer of asphalt mixtures with medium to high steel slag content are as follows: 100% passing rate through a standard sieve with a 26.5mm aperture; 98.6% passing rate through a standard sieve with a 19mm aperture; 89.4% passing rate through a standard sieve with a 16mm aperture; 78.6% passing rate through a standard sieve with a 13.2mm aperture; 63.4% passing rate through a standard sieve with a 9.5mm aperture; 42.2% passing rate through a standard sieve with a 4.75mm aperture; 27.1% passing rate through a standard sieve with a 2.36mm aperture; 19.8% passing rate through a standard sieve with a 1.18mm aperture; 13.4% passing rate through a standard sieve with a 0.6mm aperture; 8.1% passing rate through a standard sieve with a 0.3mm aperture; 6.6% passing rate through a standard sieve with a 0.15mm aperture; and 4.5% passing rate through a standard sieve with a 0.075mm aperture.

[0159] The high steel slag content anti-slip wear surface layer 6 contains steel slag aggregate with a thickness of 4.75mm or more, and limestone and mineral powder with a thickness of less than 4.75mm. The binder is high viscoelastic modified petroleum asphalt, and the additive is lignin fiber. The amount of asphalt binder is 5.9wt%, and the amount of lignin fiber is 0.33wt%. The specific composition of the aggregate is as follows: by mass ratio, 10-15mm steel slag aggregate : 5-10mm steel slag aggregate : 0-3mm limestone : mineral powder = 35 : 33 : 12 : 7.

[0160] The gradation range of the anti-slip wear surface layer with high steel slag content is as follows: 100% passing rate for a standard sieve with a 16mm aperture; 98.7% passing rate for a standard sieve with a 13.2mm aperture; 58.8% passing rate for a standard sieve with a 9.5mm aperture; 26.9% passing rate for a standard sieve with a 4.75mm aperture; 20.3% passing rate for a standard sieve with a 2.36mm aperture; 19.1% passing rate for a standard sieve with a 1.18mm aperture; 15.6% passing rate for a standard sieve with a 0.6mm aperture; 13.5% passing rate for a standard sieve with a 0.3mm aperture; 12.2% passing rate for a standard sieve with a 0.15mm aperture; and 11% passing rate for a standard sieve with a 0.075mm aperture.

[0161] The moisture content of the above-mentioned steel slag aggregate is 4.3%; the maximum dry density is 2.261 g / cm³. 3 The free calcium oxide content of the steel slag aggregate was 1.21%, and the water immersion swelling rate was 1.34%.

[0162] In this embodiment, the thickness of the all-steel slag composite asphalt pavement structure is 20cm for the all-steel slag aggregate improvement layer, 60cm for the semi-rigid base layer containing fine steel slag aggregate, 15cm for the flexible base layer containing large-diameter steel slag aggregate, 16cm for the asphalt mixture lower layer with medium to high steel slag content, and 6cm for the anti-skid and abrasion-resistant surface layer with high steel slag content.

[0163] In this embodiment, the compaction degree of the all-steel slag composite asphalt pavement structure is 97% for the all-steel slag aggregate improvement layer; the compaction degree of the semi-rigid base course containing fine steel slag aggregate is 98%; the porosity of the flexible base course containing large-diameter steel slag aggregate is 18%; and the porosity of the asphalt mixture lower layer with medium to high steel slag content and the anti-skid abrasion surface layer with high steel slag content are both 2.3%.

[0164] Subgrade and structural layer material parameters

[0165] (1) Resilient modulus of the top surface of the roadbed

[0166] The resilient modulus of the top surface of the roadbed, reduced by humidity adjustment and wet-dry or freeze-thaw cycles, is E0 = 55 MPa.

[0167] (2) Flexural strength and elastic modulus of base layer and granular layer materials

[0168] The elastic modulus of inorganic binder stabilized materials is determined by multiplying it by the structural layer modulus adjustment factor of 0.5. The specific calculation results are shown in Table 14.

[0169] Table 14 Bending strength and elastic modulus of base and improvement layer materials

[0170] Material Name Flexural tensile strength (MPa) Compressive resilient modulus (MPa) Semi-rigid base course containing fine steel slag aggregate 1.5 8300 All-steel slag granular material improvement layer 0.6 2450

[0171] (3) Modulus of asphalt surface layer and flexible base layer

[0172] The dynamic compression modulus of asphalt mixtures was selected according to the recommended range in Table 5.5.11 of the "Specifications for Design of Highway Asphalt Pavement". The test temperature was 20℃ and the loading frequency was 10Hz. The specific values ​​are shown in Table 15.

[0173] Table 15 Dynamic Compression Modulus of Asphalt Mixtures at 20℃

[0174] Asphalt mixture types Dynamic compressive modulus (MPa) Anti-slip wear surface layer with high steel slag content 12800 Medium-to-high steel slag content asphalt mixture lower layer 15500 Flexible base course containing large-diameter steel slag aggregate 19600

[0175] Note: Modified asphalt is selected as the type of asphalt.

[0176] (4) Dynamic stability of asphalt mixture layer

[0177] The test temperature was 70℃, the wheel rolling pressure was 1.0MPa, and the dynamic stability of the asphalt mixture under rutting is shown in Table 16.

[0178] Table 16 Dynamic stability of asphalt mixture rutting test

[0179] Material type Dynamic stability (cycles / mm) Anti-slip wear surface layer with high steel slag content 5128 Medium-to-high steel slag content asphalt mixture lower layer 3672 Flexible base course containing large-diameter steel slag aggregate 3014

[0180] Example 3

[0181] The all-steel slag aggregate improvement layer 2 is made by mixing and compacting 100% steel slag aggregate with water. The specific composition of the steel slag aggregate is as follows: by mass ratio, the ratio of steel slag aggregate with a particle size of 20-30mm: 10-20mm: 5-10mm: 0-5mm is 18:33:26:35.

[0182] The gradation range of the all-steel slag aggregate improvement layer is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 97.8% passing rate for a standard sieve with a 31.5mm aperture; 73.2% passing rate for a standard sieve with a 19mm aperture; 49.6% passing rate for a standard sieve with a 9.5mm aperture; 33.1% passing rate for a standard sieve with a 4.75mm aperture; 21.5% passing rate for a standard sieve with a 2.36mm aperture; 11.2% passing rate for a standard sieve with a 0.6mm aperture; and 3.3% passing rate for a standard sieve with a 0.075mm aperture.

[0183] In the semi-rigid base course 3 containing fine steel slag aggregate, the aggregate with a sieve opening smaller than 4.75 mm is steel slag aggregate, and the aggregate with a sieve opening larger than 4.75 mm is limestone aggregate; the binder is cement. The moisture content of the aggregate is 5.1%, and the maximum dry density is 2.374 g / cm³. 3 The aggregate composition is as follows: by mass ratio, 20-25mm stone: 10-20mm stone: 5-10mm stone: 3-5mm steel slag: 0-3mm steel slag = 28:31:24:12:20.

[0184] The gradation range of the semi-rigid base course containing fine steel slag aggregate is as follows: 100% passing rate for a standard sieve with a sieve aperture of 31.5 mm; 97.8% passing rate for a standard sieve aperture of 26.5 mm; 82.4% passing rate for a standard sieve aperture of 19 mm; 48.8% passing rate for a standard sieve aperture of 9.5 mm; 31.6% passing rate for a standard sieve aperture of 4.75 mm; 21.7% passing rate for a standard sieve aperture of 2.36 mm; 12.5% ​​passing rate for a standard sieve aperture of 0.6 mm; and 2.8% passing rate for a standard sieve aperture of 0.075 mm.

[0185] The flexible base course 4 containing large-diameter steel slag aggregate uses steel slag aggregate with sieve openings larger than 19mm, and limestone manufactured sand and mineral powder with sieve openings smaller than 19mm. The binder is SBS modified petroleum asphalt, with a dosage of 3.5wt%. The specific composition of the aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm limestone aggregate: 0-5mm limestone manufactured sand: mineral powder = 47:5:15:14:30:5.

[0186] The gradation range of the flexible base course containing large-diameter steel slag aggregate is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 99.6% passing rate for a standard sieve with a 31.5mm aperture; 81.8% passing rate for a standard sieve with a 26.5mm aperture; 62.7% passing rate for a standard sieve with a 19mm aperture; 45.3% passing rate for a standard sieve with a 13.2mm aperture; 28.5% passing rate for a standard sieve with a 9.5mm aperture; 17.6% passing rate for a standard sieve with a 4.75mm aperture; 11.4% passing rate for a standard sieve with a 2.36mm aperture; 9.1% passing rate for a standard sieve with a 1.18mm aperture; 6.2% passing rate for a standard sieve with a 0.6mm aperture; 3.6% passing rate for a standard sieve with a 0.3mm aperture; 3.4% passing rate for a standard sieve with a 0.15mm aperture; and 2.3% passing rate for a standard sieve with a 0.075mm aperture.

[0187] The 4.75-19mm aggregate in the lower layer 5 of the medium-high steel slag asphalt mixture is a composite of steel slag aggregate and limestone aggregate. The binder is SBS modified petroleum asphalt, with a dosage of 4.2wt%. The specific composition of the aggregate is as follows: by mass ratio, 10-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm steel slag aggregate : 0-5mm limestone manufactured sand : mineral powder = 18 : 30 : 20 : 30 : 6.

[0188] The gradation ranges for the lower layer of asphalt mixtures with medium to high steel slag content are as follows: 100% passing rate through a standard sieve with a 26.5mm aperture; 96.8% passing rate through a standard sieve with a 19mm aperture; 87.5% passing rate through a standard sieve with a 16mm aperture; 78.8% passing rate through a standard sieve with a 13.2mm aperture; 63.1% passing rate through a standard sieve with a 9.5mm aperture; 40.7% passing rate through a standard sieve with a 4.75mm aperture; 26.6% passing rate through a standard sieve with a 2.36mm aperture; 19.3% passing rate through a standard sieve with a 1.18mm aperture; 12.4% passing rate through a standard sieve with a 0.6mm aperture; 8.6% passing rate through a standard sieve with a 0.3mm aperture; 6.5% passing rate through a standard sieve with a 0.15mm aperture; and 4% passing rate through a standard sieve with a 0.075mm aperture.

[0189] The high steel slag content anti-slip wear surface layer 6 contains steel slag aggregate with a thickness of 4.75mm or more, and limestone and mineral powder with a thickness of less than 4.75mm. The binder is high viscoelastic modified petroleum asphalt, and the additive is lignin fiber. The amount of asphalt binder is 6.2wt%, and the amount of lignin fiber is 0.33wt%. The specific composition of the aggregate is as follows: by mass ratio, 10-15mm steel slag aggregate : 5-10mm steel slag aggregate : 0-3mm limestone : mineral powder = 41 : 33 : 18 : 13.

[0190] The gradation range of the anti-slip wear surface layer with high steel slag content is as follows: 100% passing rate for a standard sieve aperture of 16mm; 96.8% passing rate for a standard sieve aperture of 13.2mm; 62.2% passing rate for a standard sieve aperture of 9.5mm; 26.7% passing rate for a standard sieve aperture of 4.75mm; 20.4% passing rate for a standard sieve aperture of 2.36mm; 18.3% passing rate for a standard sieve aperture of 1.18mm; 16.0% passing rate for a standard sieve aperture of 0.6mm; 13.7% passing rate for a standard sieve aperture of 0.3mm; 13.2% passing rate for a standard sieve aperture of 0.15mm; and 10.2% passing rate for a standard sieve aperture of 0.075mm.

[0191] The moisture content of the above-mentioned steel slag aggregate is 4.3%; the maximum dry density is 2.261 g / cm³. 3 The free calcium oxide content of the steel slag aggregate is 1.24%, and the water immersion swelling rate is 1.09%.

[0192] In this embodiment, the thickness of the all-steel slag composite asphalt pavement structure is 15cm for the all-steel slag aggregate improvement layer, 60cm for the semi-rigid base layer containing fine steel slag aggregate, 15cm for the flexible base layer containing large-diameter steel slag aggregate, 16cm for the asphalt mixture lower layer with medium to high steel slag content, and 6cm for the anti-skid and abrasion-resistant surface layer with high steel slag content.

[0193] In this embodiment, the compaction degree of the all-steel slag composite asphalt pavement structure is 97% for the all-steel slag aggregate improvement layer; the compaction degree of the semi-rigid base course containing fine steel slag aggregate is 98%; the porosity of the flexible base course containing large-diameter steel slag aggregate is 17.5%; and the porosity of the asphalt mixture lower layer with medium to high steel slag content and the anti-skid abrasion surface layer with high steel slag content are both 2.6%.

[0194] Subgrade and structural layer material parameters

[0195] (1) Resilient modulus of the top surface of the roadbed

[0196] The resilient modulus of the roadbed top surface, reduced by humidity adjustment and wet-dry or freeze-thaw cycles, is E0 = 56 MPa.

[0197] (2) Flexural strength and elastic modulus of base layer and granular layer materials

[0198] The elastic modulus of inorganic binder stabilized materials is determined by multiplying it by the structural layer modulus adjustment factor of 0.5. The specific calculation results are shown in Table 17.

[0199] Table 17 Flexural Strength and Elastic Modulus of Base and Improvement Layer Materials

[0200] Material Name Flexural tensile strength (MPa) Compressive resilient modulus (MPa) Semi-rigid base course containing fine steel slag aggregate 1.6 8520 All-steel slag granular material improvement layer 0.55 2500

[0201] (3) Modulus of asphalt surface layer and flexible base layer

[0202] The dynamic compression modulus of asphalt mixtures was selected according to the recommended range in Table 5.5.11 of the "Specifications for Design of Asphalt Pavement on Highways". The test temperature was 20℃ and the loading frequency was 10Hz. The specific values ​​are shown in Table 18.

[0203] Table 18 Dynamic Compression Modulus of Asphalt Mixtures at 20℃

[0204]

[0205]

[0206] Note: Modified asphalt is selected as the type of asphalt.

[0207] (4) Dynamic stability of asphalt mixture layer

[0208] The test temperature was 70℃, the wheel rolling pressure was 1.0MPa, and the dynamic stability of the asphalt mixture rutting is shown in Table 19.

[0209] Table 19 Dynamic Stability of Asphalt Mixture Rutting Test

[0210] Material type Dynamic stability (cycles / mm) Anti-slip wear surface layer with high steel slag content 5060 Medium-to-high steel slag content asphalt mixture lower layer 3460 Flexible base course containing large-diameter steel slag aggregate 3226

[0211] Example 4

[0212] The difference from Example 1 is that the 4.75-19mm aggregate in the lower layer 5 of the medium-high steel slag content asphalt mixture is 100% steel slag aggregate. The specific composition of the aggregate is as follows: by mass ratio, 10-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm steel slag aggregate : 0-5mm steel slag aggregate : mineral powder = 16 : 31 : 23 : 27 : 3.

[0213] Everything else is the same as in Example 1.

[0214] The dynamic compression modulus of asphalt mixtures at 20℃ are as follows: surface layer 12800MPa, lower layer 14900MPa, and flexible base layer 16500MPa.

[0215] Dynamic stability of asphalt mixture rutting test: surface layer 4826 times / mm, lower layer 3150 times / mm, flexible base layer 3028 times / mm.

[0216] Comparative Example 1

[0217] The comparative example is a traditional asphalt pavement structure, and the verification analysis of its pavement structure is as follows:

[0218] Using the same traffic volume parameters as described in Example 1, and replacing the steel slag aggregate with limestone crushed stone for recalculation and analysis, the dynamic compression modulus of the asphalt mixture in Comparative Example 1 under 20°C conditions is as follows: surface layer 9000MPa, lower layer 12000MPa, and flexible base layer 16000MPa.

[0219] Dynamic stability of asphalt mixture rutting test: surface layer 1960 times / mm, lower layer 2146 times / mm, flexible base layer 2338 times / mm.

[0220] Subbase design lane equivalent design axle load cumulative action N e2 =7.681324×10 8 The road surface low-temperature cracking index (CI) is 5. All performance characteristics are inferior to the road surface structure of this invention. The road surface structure of this invention effectively improves the rutting resistance and low-temperature resistance of asphalt mixtures, and effectively reduces early road surface damage.

[0221] Comparative Example 2

[0222] The difference from Example 1 is that in the comparative example, the composite base course of the steel slag composite asphalt pavement structure consists of a semi-rigid base course containing large-diameter steel slag aggregate and a flexible base course containing fine steel slag aggregate from bottom to top.

[0223] In the flexible base course containing large-diameter steel slag aggregate, the aggregate with a sieve opening of 19mm or larger is steel slag aggregate, while the aggregate with a sieve opening of less than 19mm is limestone manufactured sand and mineral powder; the binder is SBS modified petroleum asphalt, with a dosage of 3.5wt%. The specific composition of the aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm limestone : 0-5mm limestone manufactured sand : mineral powder = 44 : 3 : 13 : 11 : 27 : 2.

[0224] The gradation ranges for flexible base courses containing large-diameter steel slag aggregates are as follows: 100% passing rate for standard sieve apertures of 37.5mm; 100% passing rate for standard sieve apertures of 31.5mm; 94.3% passing rate for standard sieve apertures of 26.5mm; 61.7% passing rate for standard sieve apertures of 19mm; 41.7% passing rate for standard sieve apertures of 13.2mm; 30.5% passing rate for standard sieve apertures of 9.5mm; 14.9% passing rate for standard sieve apertures of 4.75mm; 11.2% passing rate for standard sieve apertures of 2.36mm; 8.4% passing rate for standard sieve apertures of 1.18mm; 5.8% passing rate for standard sieve apertures of 0.6mm; 4.1% passing rate for standard sieve apertures of 0.3mm; 3.2% passing rate for standard sieve apertures of 0.15mm; and 2.3% passing rate for standard sieve apertures of 0.075mm.

[0225] In the semi-rigid base course 3 containing fine steel slag aggregate, the aggregate with a sieve opening smaller than 4.75 mm is steel slag aggregate, and the aggregate with a sieve opening larger than 4.75 mm is basalt aggregate; the binder is cement. The moisture content of the aggregate is 5.1%, and the maximum dry density is 2.374 g / cm³. 3 The aggregate composition is as follows: by mass ratio, 20-25mm stone: 10-20mm stone: 5-10mm stone: 3-5mm steel slag: 0-3mm steel slag = 25:28:21:9:17.

[0226] The gradation range of the semi-rigid base course containing fine steel slag aggregate is as follows: 100% passing rate for a standard sieve with a sieve aperture of 31.5 mm; 96.3% passing rate for a standard sieve aperture of 26.5 mm; 82.4% passing rate for a standard sieve aperture of 19 mm; 50.5% passing rate for a standard sieve aperture of 9.5 mm; 30.6% passing rate for a standard sieve aperture of 4.75 mm; 21.2% passing rate for a standard sieve aperture of 2.36 mm; 11.5% passing rate for a standard sieve aperture of 0.6 mm; and 2.5% passing rate for a standard sieve aperture of 0.075 mm.

[0227] The thickness of the semi-rigid base course containing large-diameter steel slag aggregate is 60 cm, and the thickness of the flexible base course containing fine steel slag aggregate is 15 cm. The compaction degree of the semi-rigid base course containing large-diameter steel slag aggregate is 98%; the porosity of the flexible base course containing fine steel slag aggregate is 15.5%.

[0228] The others are the same as in Example 1.

[0229] Using the same traffic volume parameters as described in Example 1, the dynamic compression modulus of the asphalt mixture in Comparative Example 2 under 20°C conditions were: 10300 MPa for the surface layer, 11500 MPa for the lower layer, and 13000 MPa for the flexible base layer.

[0230] Dynamic stability of asphalt mixture rutting test: surface layer 2080 times / mm, lower layer 2158 times / mm, flexible base layer 2260 times / mm.

[0231] Subbase design lane equivalent design axle load cumulative action N e2 =6.943167×10 8 The road surface low-temperature cracking index CI = 4. All performance characteristics are inferior to the road surface structure of this invention.

[0232] Comparative Example 3

[0233] The difference from Example 1 is that in the comparative example of the whole steel slag composite asphalt pavement structure, the asphalt surface layer from bottom to top consists of a lower layer of asphalt mixture with high steel slag content and an anti-skid and wear-resistant surface layer with medium and high steel slag content.

[0234] In the high-steel-slag-content anti-slip wear surface layer 6, the aggregates larger than 4.75mm are steel slag aggregates, and the aggregates smaller than 4.75mm are limestone and mineral powder. The binder is high-viscosity modified petroleum asphalt, and the additive is lignin fiber. The asphalt binder content is 5.9wt%, and the lignin fiber content is 0.33wt%. The specific composition of the aggregates is as follows: by mass ratio, 10-15mm steel slag aggregate : 5-10mm steel slag aggregate : 0-3mm limestone : mineral powder = 38 : 37 : 15 : 10.

[0235] The gradation range of the anti-slip wear surface layer with high steel slag content is as follows: 100% passing rate for a standard sieve aperture of 16mm; 95.2% passing rate for a standard sieve aperture of 13.2mm; 60.6% passing rate for a standard sieve aperture of 9.5mm; 30.4% passing rate for a standard sieve aperture of 4.75mm; 22.3% passing rate for a standard sieve aperture of 2.36mm; 19.8% passing rate for a standard sieve aperture of 1.18mm; 17.9% passing rate for a standard sieve aperture of 0.6mm; 15.1% passing rate for a standard sieve aperture of 0.3mm; 12.9% passing rate for a standard sieve aperture of 0.15mm; and 11.2% passing rate for a standard sieve aperture of 0.075mm.

[0236] In the lower layer 5 of the medium-high steel slag content asphalt mixture, the 4.75-19mm aggregate is a composite of steel slag aggregate and limestone aggregate. The binder is SBS modified petroleum asphalt, with a dosage of 4.2wt%. The specific composition of the aggregate is as follows: by mass ratio, 10-30mm steel slag aggregate : 10-20mm steel slag aggregate : 5-10mm steel slag aggregate : 0-5mm limestone manufactured sand : mineral powder = 16 : 31 : 23 : 27 : 3.

[0237] The gradation ranges for the lower layer of asphalt mixtures with medium to high steel slag content are as follows: 100% passing rate for a standard sieve with a 26.5mm aperture; 97.9% passing rate for a standard sieve with a 19mm aperture; 85.2% passing rate for a standard sieve with a 16mm aperture; 79.4% passing rate for a standard sieve with a 13.2mm aperture; 61.5% passing rate for a standard sieve with a 9.5mm aperture; 40.8% passing rate for a standard sieve with a 4.75mm aperture; 25.1% passing rate for a standard sieve with a 2.36mm aperture; 19.6% passing rate for a standard sieve with a 1.18mm aperture; 13.4% passing rate for a standard sieve with a 0.6mm aperture; 7.6% passing rate for a standard sieve with a 0.3mm aperture; 6.3% passing rate for a standard sieve with a 0.15mm aperture; and 5% passing rate for a standard sieve with a 0.075mm aperture.

[0238] The thickness of the asphalt mixture lower layer is 16 cm, and the thickness of the anti-skid and abrasion-resistant surface layer is 6 cm. The porosity of both the asphalt mixture lower layer and the anti-skid and abrasion-resistant surface layer is 2.5%.

[0239] The others are the same as in Example 1.

[0240] Using the same traffic volume parameters as described in Example 1, the dynamic compression modulus of the asphalt mixture in Comparative Example 3 under 20°C conditions were: 10300 MPa for the surface layer, 11000 MPa for the lower layer, and 12400 MPa for the flexible base layer.

[0241] Dynamic stability of asphalt mixture rutting test: surface layer 2020 times / mm, lower layer 2158 times / mm, flexible base layer 2286 times / mm.

[0242] Subbase design lane equivalent design axle load cumulative action N e2 =7.143267×10 8 The road surface low-temperature cracking index CI = 5. All performance characteristics are inferior to the road surface structure of this invention.

[0243] Comparative Example 4

[0244] The difference from Example 1 is that the aggregate composition of the semi-rigid base layer containing fine steel slag aggregate is as follows: by mass ratio, 20-25mm andesite: 10-20mm andesite: 5-10mm andesite: 3-5mm steel slag aggregate: 0-3mm steel slag aggregate is 25:28:21:20:30.

[0245] Using the same traffic volume parameters as described in Example 1, the dynamic compression modulus of the asphalt mixture in Comparative Example 4 under 20°C conditions were: 9200 MPa for the surface layer, 9800 MPa for the lower layer, and 10100 MPa for the flexible base layer.

[0246] Dynamic stability of asphalt mixture rutting test: surface layer 1940 times / mm, lower layer 1958 times / mm, flexible base layer 2046 times / mm.

[0247] Subbase design lane equivalent design axle load cumulative action N e2 =3.536832×10 8 Second; Road surface low-temperature cracking index CI = 3.

[0248] Comparative Example 5

[0249] The difference from Example 1 is that the specific composition of the steel slag aggregate in the all-steel slag granular material improvement layer is as follows: by mass ratio, the ratio of steel slag aggregate with particle size of 20-30mm: 10-20mm: 5-10mm: 0-5mm is 25:40:10:15.

[0250] Using the same traffic volume parameters as described in Example 1, the dynamic compression modulus of the asphalt mixture in Comparative Example 5 under 20°C conditions were: 8800 MPa for the surface layer, 9100 MPa for the lower layer, and 9950 MPa for the flexible base layer.

[0251] Dynamic stability of asphalt mixture rutting test: surface layer 1840 times / mm, lower layer 1926 times / mm, flexible base layer 1980 times / mm.

[0252] Subbase design lane equivalent design axle load cumulative action Ne2 =2.587425×10 8 The road surface low-temperature cracking index CI = 3. All performance characteristics are inferior to the road surface structure of this invention.

Claims

1. A fully steel slag composite asphalt pavement structure, located on the roadbed, comprising, from bottom to top, a roadbed improvement layer, a composite base layer, and an asphalt surface layer, characterized in that, The subgrade improvement layer is an all-steel slag granular material improvement layer; The composite base course consists of a semi-rigid base course containing fine steel slag aggregate and a flexible base course containing large-diameter steel slag aggregate, from bottom to top. The asphalt surface layer consists of, from bottom to top, a medium-to-high steel slag asphalt mixture lower layer and a high steel slag anti-skid and wear-resistant surface layer. The improved layer of all-steel slag aggregate is made by mixing and compacting 100% steel slag aggregate; In the semi-rigid base layer containing fine steel slag aggregate, the aggregate with a sieve opening of less than 4.75 mm is steel slag aggregate, and the aggregate with a sieve opening of more than 4.75 mm is stone; the binder is cement. In the flexible base layer containing large-diameter steel slag aggregate, the aggregate with a sieve opening of 19 mm or larger is steel slag aggregate, and the aggregate with a sieve opening of less than 19 mm is limestone, manufactured sand and mineral powder; the binder is asphalt. The 4.75-19mm aggregate in the lower layer of the asphalt mixture with medium to high steel slag content is a composite of steel slag aggregate and limestone aggregate or 100% steel slag aggregate. When the 4.75-19mm aggregate is a mixture of steel slag aggregate and limestone aggregate, the steel slag aggregate content in the 4.75-19mm aggregate is ≤70% of the total aggregate of the lower layer of the asphalt mixture; the binder is asphalt. The high steel slag content anti-slip wear surface layer contains steel slag aggregate with aggregates larger than 4.75mm and limestone and mineral powder with aggregates smaller than 4.75mm; the binder is asphalt and the additive is lignin fiber. The specific composition of the steel slag aggregate in the all-steel slag granular material improvement layer is as follows: by mass ratio, the ratio of steel slag aggregate with a particle size of 20-30mm: 10-20mm: 5-10mm: 0-5mm is 12-18: 27-33: 20-26: 29-35. The specific aggregate composition of the semi-rigid base course containing fine steel slag aggregate is as follows: by mass ratio, 20-25mm stone: 10-20mm stone: 5-10mm stone: 3-5mm steel slag aggregate: 0-3mm steel slag aggregate is 22-28: 25-31: 18-24: 6-12: 14-20; The moisture content of the aggregate in the semi-rigid base course containing fine steel slag is 4.8-5.2%. The aggregate composition of the flexible base layer containing large-diameter steel slag aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm limestone: 0-5mm limestone manufactured sand: mineral powder is 41-47: 10-16: 8-14: 24-30: 1-5; The asphalt binder in the flexible base course containing large-diameter steel slag aggregate is SBS-modified petroleum asphalt; the dosage of this SBS-modified petroleum asphalt is 3.2-3.8 wt%. The specific composition of the aggregate in the lower layer of the asphalt mixture with medium and high steel slag content is as follows: by mass ratio, 10-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm steel slag aggregate: 0-5mm limestone manufactured sand: mineral powder is 13-19: 28-34: 20-26: 24-30: 1-6; The asphalt binder in the lower layer of the asphalt mixture with medium to high steel slag content is SBS modified petroleum asphalt; the asphalt content is 3.9-4.5 wt%. The aggregate composition of the anti-slip wear surface layer with high steel slag content is as follows: by mass ratio, 10-15mm steel slag aggregate: 5-10mm steel slag aggregate: 0-3mm limestone: mineral powder = 35-41: 33-40: 12-18: 7-13; The asphalt binder in the aggregate of the high steel slag content anti-skid wear surface layer is high viscoelastic modified petroleum asphalt; the asphalt content is 5.6-6.2 wt%; and the lignin fiber content is 0.3-0.36 wt%. The steel slag aggregate has a moisture content of 4.0%-4.5%; the free calcium oxide content of the steel slag aggregate is ≤3%, and the water immersion expansion rate is ≤1.8%.

2. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The stone material is one or more of limestone aggregate, granite aggregate, amphibolite aggregate, or urban construction waste materials.

3. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The specific composition of the steel slag aggregate in the all-steel slag granular material improvement layer is as follows: by mass ratio, the ratio of steel slag aggregate with a particle size of 20-30mm: 10-20mm: 5-10mm: 0-5mm is 15:30:23:32; The aggregate composition of the semi-rigid base course containing fine steel slag is as follows: by mass ratio, 20-25mm stone: 10-20mm stone: 5-10mm stone: 3-5mm steel slag: 0-3mm steel slag = 25: 28: 21: 9: 17; The semi-rigid base course containing fine steel slag aggregate has an aggregate moisture content of 5.1% and a maximum dry density of 2.374 g / cm³. The specific aggregate composition of the flexible base layer containing large-diameter steel slag aggregate is as follows: by mass ratio, 20-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm limestone: 0-5mm limestone manufactured sand: mineral powder = 44:3:13:11:27:2; The amount of SBS-modified petroleum asphalt binder in the flexible base course containing large-diameter steel slag aggregate is 3.5 wt%. The specific composition of the aggregate in the lower layer of the asphalt mixture with medium and high steel slag content is as follows: by mass ratio, 10-30mm steel slag aggregate: 10-20mm steel slag aggregate: 5-10mm steel slag aggregate: 0-5mm limestone manufactured sand: mineral powder = 16:31:23:27:3; The amount of SBS-modified petroleum asphalt binder in the lower layer of the asphalt mixture with medium to high steel slag content is 4.2%. The aggregate composition of the anti-slip and wear-resistant surface layer with high steel slag content is as follows: by mass ratio, 10-15mm steel slag aggregate: 5-10mm steel slag aggregate: 0-3mm limestone: mineral powder = 38:37:15:10; The high-steel slag content anti-skid wear surface layer contains 5.9 wt% high-viscoelastic modified petroleum asphalt as the asphalt binder and 0.33 wt% lignin fiber in its aggregate. The steel slag aggregate has a moisture content of 4.3% and a maximum dry density of 2.261 g / cm³.

4. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The gradation range of the all-steel slag granular material improvement layer is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 90-100% passing rate for a standard sieve with a 31.5mm aperture; 64-84% passing rate for a standard sieve with a 19mm aperture; 40-59% passing rate for a standard sieve with a 9.5mm aperture; 24-42% passing rate for a standard sieve with a 4.75mm aperture; 14-30% passing rate for a standard sieve with a 2.36mm aperture; 6-17% passing rate for a standard sieve with a 0.6mm aperture; and 0-7% passing rate for a standard sieve with a 0.075mm aperture.

5. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The gradation range of the semi-rigid base course containing fine steel slag aggregate is as follows: 100% passing rate for a standard sieve with a 31.5mm aperture; 92-100% passing rate for a standard sieve with a 26.5mm aperture; 80-86% passing rate for a standard sieve with a 19mm aperture; 45-55% passing rate for a standard sieve with a 9.5mm aperture; 28-36% passing rate for a standard sieve with a 4.75mm aperture; 18-26% passing rate for a standard sieve with a 2.36mm aperture; 10-16% passing rate for a standard sieve with a 0.6mm aperture; and 2-5% passing rate for a standard sieve with a 0.075mm aperture.

6. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The gradation range of the flexible base course containing large-diameter steel slag aggregate is as follows: 100% passing rate for a standard sieve with a 37.5mm aperture; 90-100% passing rate for a standard sieve with a 31.5mm aperture; 70-95% passing rate for a standard sieve with a 26.5mm aperture; 40-76% passing rate for a standard sieve with a 19mm aperture; 28-58% passing rate for a standard sieve with a 13.2mm aperture; and 19-30% passing rate for a standard sieve with a 9.5mm aperture. 9%; the passing rate range for a standard sieve aperture of 4.75mm is 6-29%; the passing rate range for a standard sieve aperture of 2.36mm is 6-18%; the passing rate range for a standard sieve aperture of 1.18mm is 3-15%; the passing rate range for a standard sieve aperture of 0.6mm is 2-10%; the passing rate range for a standard sieve aperture of 0.3mm is 1-7%; the passing rate range for a standard sieve aperture of 0.15mm is 1-6%; and the passing rate range for a standard sieve aperture of 0.075mm is 1-4%.

7. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The gradation range of the lower layer of the asphalt mixture with medium and high steel slag content is as follows: 100% passing rate through a standard sieve with a 26.5mm aperture; 90-100% passing rate through a standard sieve with a 19mm aperture; 83-95% passing rate through a standard sieve with a 16mm aperture; 73-86% passing rate through a standard sieve with a 13.2mm aperture; 56-70% passing rate through a standard sieve with a 9.5mm aperture; 35-48% passing rate through a standard sieve with a 4.75mm aperture; 22-33% passing rate through a standard sieve with a 2.36mm aperture; 16-23% passing rate through a standard sieve with a 1.18mm aperture; 10-16% passing rate through a standard sieve with a 0.6mm aperture; 6-11% passing rate through a standard sieve with a 0.3mm aperture; 5-9% passing rate through a standard sieve with a 0.15mm aperture; and 4-6% passing rate through a standard sieve with a 0.075mm aperture.

8. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The gradation range of the anti-slip wear surface layer with high steel slag content is as follows: 100% passing rate for a standard sieve with a 16mm aperture; 90-100% passing rate for a standard sieve with a 13.2mm aperture; 50-75% passing rate for a standard sieve with a 9.5mm aperture; 20-34% passing rate for a standard sieve with a 4.75mm aperture; 15-26% passing rate for a standard sieve with a 2.36mm aperture; 14-24% passing rate for a standard sieve with a 1.18mm aperture; 12-20% passing rate for a standard sieve with a 0.6mm aperture; 10-16% passing rate for a standard sieve with a 0.3mm aperture; 9-15% passing rate for a standard sieve with a 0.15mm aperture; and 8-12% passing rate for a standard sieve with a 0.075mm aperture.

9. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The thickness of the all-steel slag aggregate improvement layer is 15-20cm, the thickness of the semi-rigid base layer containing fine steel slag aggregate is 50-60cm, the thickness of the flexible base layer containing large-diameter steel slag aggregate is 10-15cm, the thickness of the asphalt mixture lower layer with medium to high steel slag content is 12-16cm, and the thickness of the anti-skid and wear-resistant surface layer with high steel slag content is 4-6cm.

10. The all-steel slag composite asphalt pavement structure according to claim 1, characterized in that, The compaction degree of the all-steel slag aggregate improvement layer is ≥96%; the compaction degree of the semi-rigid base course containing fine steel slag aggregate is ≥97%; the porosity of the flexible base course containing large-diameter steel slag aggregate is 15-20%; and the porosity of the asphalt mixture lower layer with medium to high steel slag content and the anti-skid wear surface layer with high steel slag content is 2-3%.

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