Crack-resistant high-particle-size regenerated asphalt stabilized macadam material and preparation method and pavement structure thereof

Abstract

The invention provides an anti-crack high-size and large-particle-size regenerated asphalt stabilized macadam material, a preparation method thereof and a pavement structure. The regenerated asphalt stabilized macadam material comprises a base material, supplementary asphalt and a regenerant, the base material comprises an asphalt pavement solid waste material and large-particle-size gravel with the particle size larger than 30 mm and smaller than 50 mm, and the content of the asphalt pavement solid waste material is 68%-82% by taking the total mass of the base material as 100%; the content of the large-particle-size broken stones is 18%-32%; the asphalt pavement solid waste material contains old asphalt, and the content of the regenerant is 7%-9% of the old asphalt; the content of the supplementary asphalt is 0.86%-1.44% by taking the total mass of the base material as 100%. According to the invention, a rigid framework is formed by the large-particle-size broken stones, and a framework-dense structure is constructed by combining dense filling of the asphalt pavement solid waste material, so that the splitting strength is remarkably improved, the deflection value is reduced, and ruts and deformation under heavy traffic can be effectively resisted.

Description

Technical Field

[0001] This invention relates to a crack-resistant, high-strength, high-grain size recycled asphalt stabilized crushed stone material, its preparation method, and pavement structure, belonging to the field of recycled asphalt pavement materials for highway engineering. Background Technology

[0002] Asphalt pavement is the main structural form of high-grade highway pavement, generating a significant amount of asphalt pavement solid waste (RAP) annually due to major and medium-scale repairs. To protect the environment and reduce mining, the high-value and resource-based recycling of asphalt pavement materials has become a global focus in recent years. Plant-mixed hot recycling is the most widely used RAP recycling technology, but the RAP content is relatively low, generally not exceeding 30%. Cement-stabilized crushed stone, with its low price and high load-bearing capacity, has been widely used in asphalt pavements as a base structure. However, with recent economic development and the increasing heavy traffic, cement-stabilized crushed stone semi-rigid base asphalt pavement structures are subjected to repeated wheel loads during use. Cement-stabilized crushed stone materials are highly susceptible to micro-cracks, and they are also prone to drying shrinkage and thermal shrinkage cracks. The combined effect of these two factors easily leads to reflective cracking of the pavement, resulting in overall damage to the asphalt pavement.

[0003] To address the common problems of reflective cracking and poor durability in semi-rigid base asphalt pavements of high-grade highways, extensive indoor research has been conducted on asphalt-stabilized large-diameter crushed stone base courses, and related test roads have been paved. As a type of flexible structural layer, asphalt-stabilized large-diameter crushed stone base courses possess strong flexibility and deformation capacity; as a stress-dissipating layer, they can significantly improve the pavement's resistance to reflective cracking. However, this type of large-diameter asphalt-stabilized crushed stone material uses virgin aggregates instead of recycled asphalt, resulting in a higher cost—40% higher than cement-stabilized crushed stone—and therefore its usage is very limited. Secondly, the maximum particle size of asphalt-stabilized crushed stone base courses is generally 25-30mm, resulting in a structural load-bearing capacity that is about 20% lower than that of semi-rigid base courses, making them prone to rutting.

[0004] Given the technical problems existing in the current technology, it has become an urgent technical problem to be solved to develop a high-strength, crack-resistant, high-proportion recycled asphalt stabilized crushed stone material. Summary of the Invention

[0005] The problem the invention aims to solve

[0006] To address the existing technical problems in current technologies, this invention focuses on increasing the content of solid waste materials in plant-mixed hot recycled asphalt pavement. It provides a high-strength, crack-resistant, high-proportion recycled asphalt-stabilized crushed stone material to tackle the issues of easy cracking and damage in semi-rigid base asphalt pavements and the high cost and insufficient load-bearing capacity of traditional asphalt-stabilized crushed stone. This recycled asphalt-stabilized crushed stone material exhibits excellent mechanical and fatigue properties. Compared to cement-stabilized crushed stone materials, it reduces material costs and improves fatigue durability, offering significant advantages in terms of environmental friendliness, economy, and durability. It effectively solves the problems of easy cracking, short service life, and low utilization rate of solid waste materials in existing semi-rigid base asphalt pavements.

[0007] This invention uses large-diameter crushed stone (greater than 30mm and less than 50mm) and selects solid waste materials from asphalt pavement to replace materials with a diameter of less than 25mm to form a dense skeleton structure, thus creating a large-diameter recycled asphalt-stabilized crushed stone material. This improves the pavement structure's resistance to reflective cracking and its structural bearing capacity. It constructs a skeleton interlocking structure with fine aggregate densely filling the large-diameter skeleton's porosity. Through reasonable structural design and construction application, it overcomes the problems of low resource utilization rate of asphalt pavement solid waste, short pavement service life, and high construction energy consumption, providing technical support for low-carbon, high-value recycled pavement structures made from asphalt solid waste.

[0008] The present invention also provides a method for preparing recycled asphalt-stabilized crushed stone material. This preparation method is simple and easy to implement, can make full use of solid waste materials from asphalt pavement, and is suitable for mass production and has wide applications.

[0009] Solution for solving the problem

[0010] This invention provides a recycled asphalt-stabilized crushed stone material, comprising: a base material, supplementary asphalt, and a recycling agent; wherein,

[0011] The substrate comprises asphalt pavement solid waste material and large-diameter crushed stone with a particle size greater than 30 mm and less than 50 mm. Based on the total mass of the substrate (100%), the content of the asphalt pavement solid waste material is 68%-82%; the content of the large-diameter crushed stone is 18%-32%; and...

[0012] The solid waste material of the asphalt pavement contains used asphalt, and the content of the recycling agent is 7%-9% of the used asphalt;

[0013] Based on the total mass of the substrate as 100%, the content of the supplementary bitumen is 0.86%-1.44%.

[0014] According to the recycled asphalt stabilized crushed stone material of the present invention, the asphalt pavement solid waste material includes asphalt pavement solid waste material with a particle size of less than 8 mm, asphalt pavement solid waste material with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste material with a particle size of greater than 12 mm and less than 25 mm.

[0015] The mass ratio of the asphalt pavement solid waste material with a particle size of less than 8 mm, the asphalt pavement solid waste material with a particle size of greater than 8 mm and less than 12 mm, and the asphalt pavement solid waste material with a particle size of greater than 12 mm and less than 25 mm is (4.0-5.0):(1.5-2.0):(2.5-3.2).

[0016] According to the recycled asphalt-stabilized crushed stone material of the present invention, the moisture content of the asphalt pavement solid waste material is less than 3%.

[0017] Based on the mass of the solid waste material of the asphalt pavement being 100%, the content of the old asphalt is 3-5%.

[0018] According to the recycled asphalt stabilized crushed stone material of the present invention, the crushing value of the asphalt pavement solid waste material with a particle size greater than 4.75 mm and less than 25 mm is less than 26%.

[0019] According to the recycled asphalt stabilized crushed stone material of the present invention, the crushing value of the large-diameter crushed stone is less than 26%, and the moisture content of the large-diameter crushed stone is less than 2%.

[0020] The present invention also provides a method for preparing recycled asphalt stabilized crushed stone material according to the present invention, which includes the step of mixing the components of the recycled asphalt stabilized crushed stone material;

[0021] Preferably, the preparation method includes the following steps:

[0022] Heat the solid waste material of asphalt pavement to 130-150℃, heat the large-diameter crushed stone to 180-200℃, and heat the supplementary asphalt to 155-165℃.

[0023] The heated large-diameter crushed stone and solid waste material from asphalt pavement are first put into a mixing pot and dry-mixed for 30-60 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 30-60 seconds. The material is discharged after the temperature is controlled at 160-170℃ to prepare recycled asphalt stabilized crushed stone material.

[0024] The present invention also provides a road surface structure, wherein the road surface structure comprises, from top to bottom, a top layer, a bottom layer, a base layer, a first water-stabilized base layer, and a second water-stabilized base layer; wherein the base layer comprises recycled asphalt-stabilized crushed stone material according to the present invention.

[0025] According to the road structure of the present invention, the construction process of the recycled asphalt stabilized crushed stone material includes the following steps:

[0026] Paving steps: Paving is carried out using a paver. Preferably, the paving temperature is not lower than 155℃, the loose paving coefficient is 1.20-1.30, and the paving speed is 2-3m / min.

[0027] Compaction steps: A combined compaction process is used to compact the base course.

[0028] According to the road structure of the present invention, the compaction step includes initial compaction, intermediate compaction and final compaction; wherein, the initial compaction includes vibratory compaction using a double-drum roller, the intermediate compaction includes compaction using a rubber-tired roller, and the final compaction includes static compaction using a double-drum roller.

[0029] According to the pavement structure of the present invention, the pavement structure comprises, from top to bottom, a top layer, a bottom layer, a base layer, a first water-stabilized base layer, and a second water-stabilized base layer; wherein, the top layer is an SMA-13 ​​type asphalt mixture; the bottom layer is an AC-20 type asphalt mixture; the base layer is a recycled asphalt stabilized crushed stone material layer according to any one of claims 1-5; and both the first water-stabilized base layer and the second water-stabilized base layer are cement stabilized crushed stone layers.

[0030] The effects of the invention

[0031] The recycled asphalt stabilized crushed stone material of the present invention has excellent mechanical properties and stability. It forms a rigid skeleton by using large-diameter crushed stone with a particle size greater than 30mm and less than 50mm, combined with dense filling of solid waste material from asphalt pavement, to construct a skeleton-dense structure, which significantly improves splitting strength and reduces deflection value, and can effectively resist rutting and deformation under heavy traffic.

[0032] Furthermore, the recycled asphalt stabilized crushed stone material of the present invention exhibits outstanding crack resistance and durability. By utilizing the material's flexible deformation capability and through gradation optimization combined with precise compaction technology, it reduces reflective cracking after traffic commencement, and its fatigue durability life is increased by more than 30% compared to cement stabilized crushed stone.

[0033] Furthermore, the recycled asphalt stabilized crushed stone material of the present invention has strong construction adaptability, solves the segregation problem of large particle size mixtures, has a low standard deviation of flatness, and has a thinner structural layer for large particle size recycled asphalt stabilized crushed stone compared with traditional gradation.

[0034] Furthermore, the preparation method of recycled asphalt stabilized crushed stone material is simple and easy to implement, can make full use of solid waste materials from asphalt pavement, and is suitable for mass production and has a wide range of applications. Attached Figure Description

[0035] Figure 1 A schematic diagram of a road surface structure according to an application embodiment of the present invention is shown. Detailed Implementation

[0036] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0037] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0038] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0039] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0040] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0041] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0042] <First Aspect>

[0043] A first aspect of the present invention provides a recycled asphalt-stabilized crushed stone material, comprising: a base material, supplementary asphalt, and a recycling agent; wherein,

[0044] The substrate comprises asphalt pavement solid waste material and large-diameter crushed stone with a particle size greater than 30 mm and less than 50 mm. Based on the total mass of the substrate (100%), the content of the asphalt pavement solid waste material is 68%-82%; the content of the large-diameter crushed stone is 18%-32%; and...

[0045] The solid waste material of the asphalt pavement contains used asphalt, and the content of the recycling agent is 7%-9% of the used asphalt;

[0046] Based on the total mass of the substrate as 100%, the content of the supplementary bitumen is 0.86%-1.44%.

[0047] The recycled asphalt stabilized crushed stone material of the present invention has excellent mechanical properties and stability. It forms a rigid skeleton by using large-diameter crushed stone with a particle size greater than 30mm and less than 50mm, combined with dense filling of solid waste material from asphalt pavement, to construct a skeleton-dense structure, which significantly improves splitting strength and reduces deflection value, and can effectively resist rutting and deformation under heavy traffic.

[0048] Asphalt pavement solid waste materials

[0049] In this invention, based on the total mass of the substrate as 100%, the content of asphalt pavement solid waste material is 68%-82%. The 68%-82% content of asphalt pavement solid waste material in this invention is significantly higher than the content in existing recycled asphalt mixtures. By using a large amount of asphalt pavement solid waste material, a skeleton interlocking structure can be constructed, allowing the asphalt pavement solid waste material to densely fill the large-particle-size skeleton porosity. Compared to cement-stabilized crushed stone materials, material costs are reduced by more than 15%, and fatigue durability is increased by more than 30%. This demonstrates significant advantages in terms of green environmental protection, economy, and durability, effectively solving the problems of easy cracking, short service life, and low utilization rate of asphalt pavement solid waste materials in semi-rigid base asphalt pavements in my country.

[0050] Specifically, this invention selects recycled asphalt stabilized crushed stone materials with a particle size of less than 25mm to replace the original materials with a particle size of less than 25mm to form a dense skeleton structure, thereby preparing large-particle-size recycled asphalt stabilized crushed stone materials, improving the pavement structure's resistance to reflective cracking and structural bearing capacity, constructing a skeleton interlocking structure, and densely filling the large-particle-size skeleton with fine aggregates to reduce void ratio. Through reasonable structural design and construction application, it overcomes industry problems such as low solid waste resource utilization rate of asphalt pavement, short pavement service life, and high construction energy consumption.

[0051] In some specific implementations, the asphalt pavement solid waste material includes asphalt pavement solid waste material with a particle size of less than 8 mm, asphalt pavement solid waste material with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste material with a particle size of greater than 12 mm and less than 25 mm. Furthermore, by using asphalt pavement solid waste material with a particle size of less than 8 mm, asphalt pavement solid waste material with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste material with a particle size of greater than 12 mm and less than 25 mm, the voids in the large-diameter crushed stone can be fully filled, achieving dense filling, thereby constructing a skeleton-dense structure, further improving splitting strength, and reducing deflection value.

[0052] Specifically, the mass ratio of asphalt pavement solid waste material with a particle size of less than 8 mm, asphalt pavement solid waste material with a particle size greater than 8 mm and less than 12 mm, and asphalt pavement solid waste material with a particle size greater than 12 mm and less than 25 mm is (4.0-5.0):(1.5-2.0):(2.5-3.2). When the mass ratio of asphalt pavement solid waste material with a particle size of less than 8 mm, asphalt pavement solid waste material with a particle size greater than 8 mm and less than 12 mm, and asphalt pavement solid waste material with a particle size greater than 12 mm and less than 25 mm is (4.0-5.0):(1.5-2.0):(2.5-3.2), the function of the asphalt pavement solid waste material can be most effectively exerted.

[0053] Furthermore, in this invention, the moisture content of the asphalt pavement solid waste material is below 3%; and based on the mass of the asphalt pavement solid waste material as 100%, the content of the old asphalt is 3-5%. By using asphalt pavement solid waste material, this invention allows for the full utilization of the old asphalt within the material, requiring only a small amount of supplementary asphalt to obtain recycled asphalt-stabilized crushed stone material.

[0054] In some specific implementation schemes, the crushing value of asphalt pavement solid waste materials with a particle size greater than 4.75 mm and less than 25 mm is below 26%. When the crushing value of these materials is below 26%, they are less likely to be crushed under repeated vehicle loads, forming a stable interlocking skeleton structure with enhanced compressive strength. Asphalt pavement solid waste materials with a particle size greater than 4.75 mm and less than 25 mm can be obtained through screening.

[0055] This invention utilizes the flexible deformation capacity of solid waste materials from asphalt pavement, and through gradation optimization and precise compaction processes, reduces reflective cracking after traffic commencement, increasing fatigue durability by more than 30% compared to cement-stabilized crushed stone.

[0056] By using the recycled asphalt-stabilized crushed stone material of this invention, high-value recycling of solid waste materials from asphalt pavement can be achieved, reducing solid waste accumulation and mining.

[0057] Large-diameter crushed stone

[0058] The large-diameter crushed stone of this invention has a particle size greater than 30 mm and less than 50 mm. This invention uses large-diameter crushed stone as the main skeleton of the recycled asphalt stabilized crushed stone material, thereby forming a skeleton interlocking structure. The interlocking effect between the large-diameter crushed stones can resist load deformation and is beneficial for the dense filling of solid waste materials in asphalt pavements.

[0059] In this invention, based on the total mass of the substrate as 100%, the content of large-diameter crushed stone is 18%-32%. When the content of large-diameter crushed stone is 18%-32%, it is beneficial to form a skeleton interlocking structure, which enables the dense filling of solid waste materials in asphalt pavement, thereby obtaining the desired recycled asphalt stabilized crushed stone material.

[0060] In some specific implementation schemes, the crushing value of the large-diameter crushed stone is below 26%. When the crushing value of the large-diameter crushed stone is below 26%, it ensures that the crushed stone possesses good resistance to crushing, forming a stable interlocking skeleton, effectively improving the bearing capacity and deformation resistance of the pavement structure, while avoiding excessive particle crushing and gradation loss during construction compaction, ensuring a uniform and dense structural layer. The moisture content of the large-diameter crushed stone is below 2%.

[0061] Other components

[0062] This invention also includes supplementary asphalt and a recycling agent. Since asphalt pavement solid waste materials contain old asphalt, only a small amount of asphalt needs to be added, and appropriate recycling agents are used to obtain recycled asphalt-stabilized crushed stone materials.

[0063] In this invention, the asphalt pavement solid waste material contains recycled asphalt, and the content of the recycling agent is 7%-9% of the recycled asphalt. The invention does not impose any particular limitation on the recycling agent; it can be a recycling agent commonly used in the art. Specifically, the recycling agent can be one or a combination of two or more of the following: RA-25 type recycling agent, Runqiang-RA102 asphalt recycling agent, JM-RA recycling agent, etc.

[0064] Since solid waste materials for asphalt pavement contain a significant amount of old asphalt, only a small amount of additional asphalt is needed. Specifically, based on the total mass of the substrate (100%), the content of the additional asphalt is 0.86%-1.44%. The type of additional asphalt is not particularly limited in this invention; it can be any asphalt commonly used in the art, such as 70# road petroleum asphalt.

[0065] The recycled asphalt stabilized crushed stone material of the present invention is suitable for heavy traffic sections (such as national and provincial trunk highways) and old road repair projects, and can maintain stable performance in complex climate areas such as high temperature (road surface temperature above 70°C) and rainy areas.

[0066] <Preparation Method>

[0067] A second aspect of the present invention provides a method for preparing a recycled asphalt-stabilized crushed stone material according to the first aspect of the present invention, comprising the step of mixing the components of the recycled asphalt-stabilized crushed stone material;

[0068] Preferably, the preparation method includes the following steps:

[0069] Heat the solid waste material of asphalt pavement to 130-150℃, heat the large-diameter crushed stone to 180-200℃, and heat the supplementary asphalt to 155-165℃.

[0070] The heated large-diameter crushed stone and solid waste material from asphalt pavement are first put into a mixing pot and dry-mixed for 30-60 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 30-60 seconds. The material is discharged after the temperature is controlled at 160-170℃ to prepare recycled asphalt stabilized crushed stone material.

[0071] The mixing method of this invention can solve the problem of segregation in large-particle-size mixtures, resulting in a low standard deviation of smoothness. This allows for a thinner base course in subsequent road structures.

[0072] <Second aspect>

[0073] A second aspect of the present invention provides a road surface structure, which comprises, from top to bottom, a top layer, a bottom layer, a base layer, a first water-stabilized base layer, and a second water-stabilized base layer; wherein the base layer comprises recycled asphalt-stabilized crushed stone material according to the first aspect.

[0074] This invention improves the pavement's resistance to reflective cracking and its load-bearing capacity by using recycled asphalt-stabilized crushed stone as a flexible base layer, i.e., a stress-dissipating layer, between the asphalt surface layer and the semi-rigid base layer.

[0075] In some specific implementation schemes, the construction process of the recycled asphalt stabilized crushed stone material includes the following steps:

[0076] Paving steps: Paving is carried out using a paver. Preferably, the paving temperature is not lower than 155℃, the loose paving coefficient is 1.20-1.30, and the paving speed is 2-3m / min.

[0077] Compaction steps: A combined compaction process is used to compact the base course.

[0078] In some specific implementations, the compaction step includes initial compaction, intermediate compaction, and final compaction; wherein, the initial compaction includes vibratory compaction using a double-drum roller, the intermediate compaction includes compaction using a rubber-tired roller, and the final compaction includes static compaction using a double-drum roller.

[0079] In some specific implementations, in this invention, the initial compaction can be achieved by vibratory compaction with a double-drum roller for 2 or more passes at a speed of 2-3 km / h, with an initial temperature ≥150℃; the secondary compaction can be achieved by compaction with a rubber-tired roller for 7-8 passes, followed by vibratory compaction with a single-drum roller for 2-3 passes, and vibratory compaction with a double-drum roller for 2-4 passes, at a speed of 4-5 km / h; the final compaction can be achieved by static compaction with a double-drum roller for 2 or more passes at a speed of 3-4 km / h, with a final surface temperature ≥110℃.

[0080] In some specific implementation schemes, the road structure consists of, from top to bottom, a top layer, a bottom layer, a base layer, a first water-stabilized base layer, and a second water-stabilized base layer; wherein, the top layer is an SMA-13 ​​type asphalt mixture; the bottom layer is an AC-20 type asphalt mixture; the base layer is a recycled asphalt stabilized crushed stone material layer according to any one of claims 1-5; and both the first water-stabilized base layer and the second water-stabilized base layer are cement stabilized crushed stone layers.

[0081] The present invention does not impose any particular limitation on the construction process of other layers; any feasible construction process in the field may be used.

[0082] Example

[0083] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0084] Example 1

[0085] Project Overview: This is a major overhaul project for a highway with a design speed of 120 km / h and a heavy traffic ratio of 30%. Large-diameter recycled asphalt stabilized crushed stone material (10 cm thick) is used as the base course to replace the AC-25 base course. The base material of the large-diameter recycled asphalt stabilized crushed stone material includes asphalt pavement solid waste material (RAP) and large-diameter crushed stone. The content of asphalt pavement solid waste material is 80%, and the content of large-diameter crushed stone is 20%.

[0086] Raw material parameters

[0087] Asphalt pavement solid waste (RAP): Moisture content 2.5%, old asphalt content 4.2%, penetration at 25℃ 25×0.1mm, and crushing value of 23% for asphalt pavement solid waste with a particle size greater than 4.75mm and less than 25mm.

[0088] The mass ratio of asphalt pavement solid waste materials with a particle size of less than 8 mm, asphalt pavement solid waste materials with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste materials with a particle size of greater than 12 mm and less than 25 mm is 5:2:3.

[0089] Large-diameter crushed stone: with a particle size greater than 30mm and less than 50mm, a crushing value of 22%, and a moisture content of 1.8%.

[0090] Recycling agent: RA-25 type, viscosity at 60℃ is 2500mm² / s, flash point is 230℃, and the content of recycling agent is 8% of the old asphalt content in solid waste materials of asphalt pavement.

[0091] Supplementary asphalt: 70# road petroleum asphalt, penetration 68×0.1mm, softening point 46℃, supplementary asphalt content is 0.87%.

[0092] Preparation process:

[0093] The solid waste material of the asphalt pavement is heated to 130°C, the large-diameter crushed stone is heated to 190°C, and the supplementary asphalt is heated to 160°C.

[0094] The heated large-diameter crushed stone and asphalt pavement solid waste materials are first put into a mixing pot and dry-mixed for 50 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 40 seconds. The material is discharged after the temperature is controlled at 160℃ to prepare recycled asphalt stabilized crushed stone material.

[0095] Example 2

[0096] Project Overview: This is a major overhaul project for a national and provincial trunk highway with a design speed of 100 km / h. Large-particle-size recycled asphalt stabilized crushed stone material is used as a flexible base course (11 cm thick) to replace the AC-25 base course. The base material of the large-particle-size recycled asphalt stabilized crushed stone material includes asphalt pavement solid waste material (RAP) and large-particle-size crushed stone. The content of asphalt pavement solid waste material is 70%, and the content of large-particle-size crushed stone is 30%.

[0097] Raw material parameters

[0098] Asphalt pavement solid waste (RAP): Moisture content 2.5%, old asphalt content 4.3%, penetration at 25℃ 25×0.1mm, and crushing value of 23% for asphalt pavement solid waste with a particle size greater than 4.75mm and less than 25mm.

[0099] The mass ratio of asphalt pavement solid waste materials with a particle size of less than 8 mm, asphalt pavement solid waste materials with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste materials with a particle size of greater than 12 mm and less than 25 mm is approximately 5:1.94:3.06.

[0100] Large-diameter crushed stone: with a particle size greater than 30mm and less than 50mm, a crushing value of 22%, and a moisture content of 1.8%.

[0101] Recycling agent: RA-25 type, viscosity at 60℃ is 2500mm² / s, flash point is 230℃, and the content of recycling agent is 8% of the old asphalt content in solid waste materials of asphalt pavement.

[0102] Supplementary asphalt: 70# road petroleum asphalt, penetration 68×0.1mm, softening point 46℃, supplementary asphalt content is 1.06%.

[0103] Preparation process:

[0104] The solid waste material of the asphalt pavement is heated to 135°C, the large-diameter crushed stone is heated to 185°C, and the supplementary asphalt is heated to 155°C.

[0105] The heated large-diameter crushed stone and asphalt pavement solid waste materials are first put into a mixing pot and dry-mixed for 50 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 40 seconds. The material is discharged after the temperature is controlled at 165℃ to prepare recycled asphalt stabilized crushed stone material.

[0106] Example 3

[0107] Project Overview: A certain project has a design speed of 80 km / h and a heavy traffic ratio of 20%. The base course uses large-particle-size recycled asphalt stabilized crushed stone material. The base material of the large-particle-size recycled asphalt stabilized crushed stone material includes asphalt pavement solid waste material (RAP) and large-particle-size crushed stone. The content of asphalt pavement solid waste material is 75%, and the content of large-particle-size crushed stone is 25%.

[0108] Raw material parameters

[0109] Asphalt pavement solid waste (RAP): moisture content 2.45%, old asphalt content 4.2%, penetration at 25℃ 26×0.1mm, and crushing value of 21% for asphalt pavement solid waste with a particle size greater than 4.75mm and less than 25mm.

[0110] The mass ratio of asphalt pavement solid waste materials with a particle size of less than 8 mm, asphalt pavement solid waste materials with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste materials with a particle size of greater than 12 mm and less than 25 mm is approximately 4.8:1.8:2.9.

[0111] Large-diameter crushed stone: with a particle size greater than 30mm and less than 50mm, a crushing value of 21%, and a moisture content of 1.7%.

[0112] Recycling agent: RA-25 type, viscosity at 60℃ is 2500mm² / s, flash point is 230℃, and the content of recycling agent is 8% of the old asphalt content in solid waste materials of asphalt pavement.

[0113] Supplementary asphalt: 70# road petroleum asphalt, penetration 68×0.1mm, softening point 46℃, supplementary asphalt content is 1.06%.

[0114] Preparation process:

[0115] The solid waste material of the asphalt pavement is heated to 135°C, the large-diameter crushed stone is heated to 190°C, and the supplementary asphalt is heated to 160°C.

[0116] The heated large-diameter crushed stone and solid waste material from asphalt pavement are first put into a mixing pot and dry-mixed for 30 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 30 seconds. The material is discharged after the temperature is controlled at 165℃ to prepare recycled asphalt stabilized crushed stone material.

[0117] Example 4

[0118] Project Overview: A certain project has a design speed of 100km / h and a heavy traffic ratio of 30%. The base course uses large-particle-size recycled asphalt stabilized crushed stone material. The base material of the large-particle-size recycled asphalt stabilized crushed stone material includes asphalt pavement solid waste material (RAP) and large-particle-size crushed stone. The content of asphalt pavement solid waste material is 78%, and the content of large-particle-size crushed stone is 22%.

[0119] Raw material parameters

[0120] Asphalt pavement solid waste (RAP): Moisture content 2.6%, old asphalt content 3.9%, penetration at 25℃ 26×0.1mm, crushing value of asphalt pavement solid waste with particle size greater than 4.75mm and less than 25mm 21%.

[0121] The mass ratio of asphalt pavement solid waste materials with a particle size of less than 8 mm, asphalt pavement solid waste materials with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste materials with a particle size of greater than 12 mm and less than 25 mm is approximately 4.6:1.6:2.8.

[0122] Large-diameter crushed stone: greater than 30mm and less than 50mm, crushing value 21%, moisture content 1.7%.

[0123] Recycling agent: RA-25 type, viscosity at 60℃ is 2500mm² / s, flash point is 230℃, and the content of recycling agent is 8% of the old asphalt content in solid waste materials of asphalt pavement.

[0124] Supplementing asphalt: 70# road petroleum asphalt, penetration 68×0.1mm, softening point 46℃, new asphalt-aggregate ratio is 1.06%.

[0125] Preparation process:

[0126] The solid waste material of the asphalt pavement is heated to 135°C, the large-diameter crushed stone is heated to 195°C, and the supplementary asphalt is heated to 165°C.

[0127] The heated large-diameter crushed stone and solid waste material from asphalt pavement are first put into a mixing pot and dry-mixed for 35 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 35 seconds. The material is discharged after the temperature is controlled at 165℃ to prepare recycled asphalt stabilized crushed stone material.

[0128] Comparative Example 1

[0129] Project Overview: A major overhaul project of a national and provincial trunk road uses large-particle-size recycled asphalt stabilized crushed stone material as a flexible base course (11cm thick) to replace the AC-25 base course. The base material of the large-particle-size recycled asphalt stabilized crushed stone material includes asphalt pavement solid waste material (RAP) and large-particle-size crushed stone, with the content of asphalt pavement solid waste material being 50% and the content of large-particle-size crushed stone being 50%.

[0130] Asphalt pavement solid waste (RAP): Moisture content 2.5%, old asphalt content 4.2%, penetration at 25℃ 25×0.1mm, and crushing value of 23% for asphalt pavement solid waste with a particle size greater than 4.75mm and less than 25mm.

[0131] The mass ratio of asphalt pavement solid waste materials with a particle size of less than 8 mm, asphalt pavement solid waste materials with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste materials with a particle size of greater than 12 mm and less than 25 mm is 5:2:3.

[0132] Large-diameter crushed stone: with a particle size greater than 30mm and less than 50mm, a crushing value of 22%, and a moisture content of 1.8%.

[0133] Recycling agent: RA-25 type, viscosity at 60℃ is 2500mm² / s, flash point is 230℃, and the content of recycling agent is 8% of the old asphalt content in solid waste materials of asphalt pavement.

[0134] Supplementing asphalt: 70# road petroleum asphalt, penetration 68×0.1mm, softening point 46℃, new asphalt-aggregate ratio is 0.87%.

[0135] Preparation process:

[0136] The solid waste material of the asphalt pavement is heated to 130°C, the large-diameter crushed stone is heated to 200°C, and the supplementary asphalt is heated to 165°C.

[0137] The heated large-diameter crushed stone and solid waste material from asphalt pavement are first put into a mixing pot and dry-mixed for 50 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 40 seconds. The material is discharged after the temperature is controlled at 170℃ to prepare recycled asphalt stabilized crushed stone material.

[0138] Performance testing

[0139] Relevant testing and detection methods:

[0140] 1. Maximum theoretical relative density

[0141] The tests were conducted according to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTG 3410-2025) T 0711, and the results are shown in Table 1.

[0142] 2. Relative density of hair volume

[0143] The tests were conducted according to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTG 3410-2025) T 0706, and the results are shown in Table 1.

[0144] 3. Compressive strength (MPa)

[0145] The tests were conducted according to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTG 3410-2025) T 0713, and the results are shown in Table 1.

[0146] 4. Splitting strength (MPa)

[0147] The tests were conducted according to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTG 3410-2025) T 0806, and the results are shown in Table 1.

[0148] 5. Dynamic stability (cycles / mm)

[0149] The tests were conducted according to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTG 3410-2025) T 0719, and the results are shown in Table 1.

[0150] Table 1 Comparison of performance test results between each embodiment and the comparative example

[0151]

[0152] As can be seen from Table 1, the large-particle-size recycled asphalt stabilized crushed stone materials of Examples 1-4 of the present invention have better performance effects, while the comparative examples have no relevant performance effects because they could not be properly molded.

[0153] Application Examples

[0154] 1. Cement-stabilized crushed stone is paved using a paver to form a second water-stabilized layer with a thickness of 20cm. The paving speed is 2-3m / min, and the loose paving coefficient is 1.3. A combination of double-drum roller and rubber-tired roller is used for compaction. The initial compaction is done with two passes of vibratory rolling (speed 2km / h), the intermediate compaction is done with six passes of static rolling (speed 3km / h), and the final compaction is done with two passes of static rolling (speed 4km / h). After 7 days of curing (moisture curing, strength reaches 3.5MPa), the compaction degree is tested to be 99%, and the thickness deviation is ±8%.

[0155] 2. Cement-stabilized crushed stone was paved using a paver to form the first water-stabilized layer, with a thickness of 20cm. The paving speed was 3m / min, and the loose paving coefficient was 1.3. A combination of double-drum roller and rubber-tired roller was used for compaction. The initial compaction was done with two passes of vibratory rolling (speed 2km / h), the intermediate compaction with six passes of static rolling (speed 3km / h), and the final compaction with two passes of static rolling (speed 4km / h). After 7 days of curing (moisture curing, strength reaching 3.5MPa), the compaction degree was tested to be 98.5%, and the thickness deviation was ±8%.

[0156] 3. Preheat the paver screed to 110℃, then pave the recycled asphalt stabilized crushed stone material to form a base course with a thickness of 10cm. The paving temperature is 155℃, the speed is 2m / min, and the loose paving coefficient is 1.25. Next, vibratory compaction is performed twice with a double-drum roller at a speed of 2km / h, with an initial temperature of 150℃. Then, seven passes are performed with a rubber-tired roller, followed by two passes with a single-drum roller and four passes with a double-drum roller, at a speed of 4km / h. Finally, two passes are performed with a double-drum roller at a speed of 3km / h, resulting in a final surface temperature of 110℃. The compaction degree reaches 98% (laboratory standard density), the smoothness is 3mm, and the thickness deviation is ±8%. Curing is continued until the surface temperature reaches 50℃ before proceeding to the next layer.

[0157] 4. AC-20 asphalt mixture was paved using a paver to form the lower layer, which was 6cm thick. The paving speed of the paver was 2m / min and the paving temperature was 145℃. The compaction was carried out using a double steel drum roller, with two passes of initial compaction vibration (temperature 140℃), four passes of secondary compaction vibration, and two passes of final static compaction (final temperature 100℃). The compaction degree was tested to be 98% and the smoothness was 1.5mm.

[0158] 5. SMA13 asphalt mixture was paved using a paver to form the surface layer, with a thickness of 4cm. The paver speed was 2m / min, and the paving temperature was 150℃. Compaction was performed using a double-drum roller, with two passes of initial vibration (temperature 140℃), four passes of secondary vibration, and two passes of final static compaction (final temperature 100℃). Testing showed a compaction degree of 98%, a smoothness of 2mm, and a texture depth of 0.5mm, resulting in the pavement structure as follows: Figure 1 As shown.

[0159] Application of comparative examples

[0160] 1. Cement-stabilized crushed stone was paved using a paver to form a second water-stabilized layer with a thickness of 20cm. The paving speed was 2m / min, and the loose paving coefficient was 1.3. A combination of double-drum roller and rubber-tired roller was used for compaction. The initial compaction was done with two passes of vibratory rolling (speed 2km / h), the intermediate compaction with six passes of static rolling (speed 3km / h), and the final compaction with two passes of static rolling (speed 4km / h). After 7 days of curing (moisture curing, strength 3.5MPa), the compaction degree was tested and the thickness deviation was ±8%.

[0161] 2. Cement-stabilized crushed stone was paved using a paver to form the first water-stabilized layer, with a thickness of 36cm. The paving speed was 2m / min, and the loose paving coefficient was 1.3. A combination of double-drum roller and rubber-tired roller was used for compaction. The initial compaction was done with two passes of vibratory rolling (speed 2km / h), followed by four passes of static rolling (speed 3km / h) and two passes of static rolling (speed 4km / h). After 7 days of curing (moisture curing, strength 3.6MPa), the compaction degree was tested and the thickness deviation was ±8%.

[0162] 3. Preheat the paver screed to 110℃, then pave the AC-25 asphalt mixture to form a base course with a thickness of 8cm. The paving temperature is 155℃, the speed is 2m / min, and the loose paving coefficient is 1.25. Perform two passes of vibratory compaction with a double-drum roller at a speed of 2km / h, with an initial temperature of 150℃. Then, perform seven passes with a rubber-tired roller, followed by two passes of vibratory compaction with a single-drum roller, and four passes of vibratory compaction with a double-drum roller at a speed of 4km / h. Finally, perform two passes of static compaction with a double-drum roller at a speed of 4km / h, achieving a final surface temperature of 110℃. The compaction degree should be 98% (laboratory standard density), the smoothness ≤3mm, and the thickness deviation ±8%. Curing should continue until the surface temperature reaches 50℃ before proceeding to the next layer.

[0163] 4. AC-20 asphalt mixture was paved using a paver to form the lower layer, which was 6cm thick. The paving speed of the paver was 2m / min and the paving temperature was 135℃. The compaction was carried out using a double-drum roller, with two passes of initial compaction vibration (temperature 130℃), four passes of secondary compaction vibration, and two passes of final static compaction (final temperature 100℃). The compaction degree was tested to be 98% and the smoothness was 2.5mm.

[0164] 5. SMA13 asphalt mixture was paved using a paver to form the surface layer, which was 4cm thick. The paving speed was 1.5m / min and the paving temperature was 150℃. The compaction was carried out using a double-drum roller, with two passes of initial compaction vibration (temperature 140℃), four passes of secondary compaction vibration, and two passes of final static compaction (final temperature 100℃). The compaction degree was tested to be 98%, the smoothness was 2mm, and the texture depth was 0.4mm, resulting in the pavement structure.

[0165] Performance testing

[0166] The bearing capacity of the two pavement structures in the application examples and comparative examples was evaluated using dynamic deflection values ​​obtained by FWD (Falling Weight Deflectometer). The test was conducted in accordance with T 0953-2019 "Deflection Test Method of Falling Weight Deflectometer" in the "Specifications for Field Testing of Highway Subgrade and Pavement" (JTG 3450-2019).

[0167] The test results are as follows: Under a standard load of 50kN, the FWD dynamic deflection value of the application example is 0.15mm, and the FWD dynamic deflection value of the application comparison example is 0.18mm.

[0168] The test results show that the pavement structure layer using large-particle-size recycled asphalt stabilized crushed stone material has a smaller deflection value, which significantly improves the overall stiffness of the pavement structure, that is, improves the overall load-bearing capacity of the pavement structure.

[0169] The large-particle-size recycled asphalt stabilized crushed stone material of the present invention can realize the high-value recycling of old asphalt pavement (RAP), reduce solid waste accumulation and mining, save 0.765 tons of stone per ton of mixture, and reduce carbon emissions by about 20%.

[0170] In addition, the large-particle-size recycled asphalt stabilized crushed stone material of the present invention has a wide range of applications: it is suitable for heavy traffic sections (such as national and provincial trunk highways) and old road repair projects, and can maintain stable performance in complex climate zones such as high temperature (road surface temperature above 70°C) and rainy areas.

[0171] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0172] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A recycled asphalt-stabilized crushed stone material, characterized in that, include: Substrate, supplementary bitumen, and recycling agent; among which, The substrate comprises asphalt pavement solid waste material and large-diameter crushed stone with a particle size greater than 30 mm and less than 50 mm. Based on the total mass of the substrate (100%), the content of the asphalt pavement solid waste material is 68%-82%; the content of the large-diameter crushed stone is 18%-32%; and... The solid waste material of the asphalt pavement contains used asphalt, and the content of the recycling agent is 7%-9% of the used asphalt; Based on the total mass of the substrate as 100%, the content of the supplementary bitumen is 0.86%-1.44%.

2. The recycled asphalt-stabilized crushed stone material according to claim 1, characterized in that, The asphalt pavement solid waste materials include asphalt pavement solid waste materials with a particle size of less than 8 mm, asphalt pavement solid waste materials with a particle size of greater than 8 mm and less than 12 mm, and asphalt pavement solid waste materials with a particle size of greater than 12 mm and less than 25 mm. The mass ratio of the asphalt pavement solid waste material with a particle size of less than 8 mm, the asphalt pavement solid waste material with a particle size of greater than 8 mm and less than 12 mm, and the asphalt pavement solid waste material with a particle size of greater than 12 mm and less than 25 mm is (4.0-5.0):(1.5-2.0):(2.5-3.2).

3. The recycled asphalt-stabilized crushed stone material according to claim 1 or 2, characterized in that, The moisture content of the solid waste material for the asphalt pavement is below 3%; Based on the mass of the solid waste material of the asphalt pavement being 100%, the content of the old asphalt is 3-5%.

4. The recycled asphalt-stabilized crushed stone material according to any one of claims 1-3, characterized in that, The crushing value of solid waste materials from asphalt pavement with a particle size greater than 4.75 mm and less than 25 mm is less than 26%.

5. The recycled asphalt-stabilized crushed stone material according to any one of claims 1-4, characterized in that, The crushing value of the large-diameter crushed stone is below 26%, and the moisture content of the large-diameter crushed stone is below 2%.

6. A method for preparing recycled asphalt-stabilized crushed stone material according to any one of claims 1-5, characterized in that, This includes the step of mixing the components of the recycled asphalt-stabilized crushed stone material; Preferably, the preparation method includes the following steps: Heat the solid waste material of asphalt pavement to 130-150℃, heat the large-diameter crushed stone to 180-200℃, and heat the supplementary asphalt to 155-165℃. The heated large-diameter crushed stone and solid waste material from asphalt pavement are first put into a mixing pot and dry-mixed for 30-60 seconds. Then, a recycling agent is added, followed by the addition of heated supplementary asphalt and wet-mixed for 30-60 seconds. The material is discharged after the temperature is controlled at 160-170℃ to prepare recycled asphalt stabilized crushed stone material.

7. A road surface structure, characterized in that, The road structure comprises, from top to bottom, a top layer, a bottom layer, a base layer, a first water-stabilized base layer, and a second water-stabilized base layer; wherein the base layer comprises recycled asphalt-stabilized crushed stone material according to any one of claims 1-5.

8. The road structure according to claim 7, characterized in that, The construction process of the recycled asphalt stabilized crushed stone material includes the following steps: Paving steps: Paving is carried out using a paver. Preferably, the paving temperature is not lower than 155℃, the loose paving coefficient is 1.20-1.30, and the paving speed is 2-3m / min. Compaction steps: A combined compaction process is used to compact the base course.

9. The road structure according to claim 8, characterized in that, The compaction steps include initial compaction, intermediate compaction, and final compaction; wherein, the initial compaction includes vibratory compaction using a double-drum roller, the intermediate compaction includes compaction using a rubber-tired roller, and the final compaction includes static compaction using a double-drum roller.

10. The pavement structure according to claim 7, characterized in that, The road structure consists of, from top to bottom, an upper layer, a lower layer, a base layer, a first water-stabilized base layer, and a second water-stabilized base layer; wherein, the upper layer is an SMA-13 ​​type asphalt mixture; the lower layer is an AC-20 type asphalt mixture; the base layer is a recycled asphalt stabilized crushed stone material layer according to any one of claims 1-5; and both the first water-stabilized base layer and the second water-stabilized base layer are cement stabilized crushed stone layers.

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