Inverted roadbed and pavement structure using comprehensive utilization of solid waste

Abstract

The present invention discloses an inverted roadbed and pavement structure for comprehensive utilization of solid waste, comprising an upper embankment paved sequentially with recycled aggregates from demolition and construction solid waste, a roadbed paved with cement-desulfurized slag-gypsum composite stabilized engineering slag, a pavement subbase paved with recycled aggregates from demolition and construction solid waste stabilized with desulfurized gypsum-cement, an upper pavement base paved with graded crushed stone from recycled aggregates from waste concrete, a lower and middle pavement layer paved with factory-mixed hot-recycled SBS modified asphalt mixture, an upper layer paved with semi-flexible pavement material, and an asphalt wearing course paved with a high-viscosity modified asphalt mixture. The present invention optimizes and combines the design based on the stress characteristics and functional features of each structural layer, can be used on high-grade roads, and has the characteristics of long service life, high driving safety, and high comfort. The material selection of each structural layer conforms to the concept of green ecological development under the background of "dual carbon" and realizes the rational utilization of large amounts of solid waste in the road engineering field.

Description

Technical Field

[0001] The present invention belongs to the technical field of road engineering, and in particular relates to an inverted roadbed and pavement structure for comprehensive utilization of solid waste. Background Art

[0002] With the development of urban renewal and construction in my country, especially in the construction of new urban areas, the demolition of numerous obsolete buildings has generated a significant amount of construction and demolition solid waste. Earthwork balancing during construction produces a large amount of construction debris, and excavation of roads produces a large amount of recycled SBS-modified asphalt pavement material. The storage and landfilling of solid waste not only consumes land resources but also pollutes the environment. Currently, the resource utilization rate of industrial solid wastes such as slag and desulfurized gypsum is low. Therefore, the combined application of construction and demolition solid waste, construction debris, recycled SBS-modified asphalt pavement material, and industrial solid waste in roadbed and pavement structures can be considered comprehensive solid waste utilization. Road construction consumes a large amount of sand and gravel aggregate, which is increasingly scarce in the context of ecologically sustainable development. The comprehensive utilization of solid waste in road construction not only achieves the resource utilization of multiple sources of solid waste but also addresses the shortage of road construction materials, offering significant economic, social, and environmental benefits. Previous studies have shown that these various types of solid waste can be transformed into high-quality road construction materials through processing and refined mix design.

[0003] In recent years, with the advent of quality engineering, high-quality, high-standard construction, and long-life asphalt pavement structures, insufficient roadbed strength has become a major factor affecting pavement life, in addition to the performance of the pavement itself. The pavement structure currently used on high-grade roads in my country is primarily a semi-rigid base asphalt pavement structure. To date, semi-rigid base asphalt pavement structures still suffer from reflective cracking. Research has shown that an inverted pavement structure, in which graded gravel is laid on a semi-rigid base structure and a stress-absorbing layer is installed, can effectively prevent reflective cracking. Therefore, in the context of my country's high-quality, sustainable road transportation development, a design for an inverted roadbed pavement structure that comprehensively utilizes solid waste is proposed. This is necessary to achieve the resourceful utilization of multiple sources of solid waste while ensuring the overall performance of the road structure. A search revealed that Chinese patent CN212714350U discloses a low-grade road structure using multi-source solid waste, proposing the use of inorganic stabilized aggregates from demolition solid waste as the pavement base layer, with factory-mixed hot recycled asphalt mixture used for paving the lower layer. Chinese patent CN209722626U discloses a road structure based on an inorganic mixture stabilized with recycled fly ash from construction waste, proposing the use of inorganic stabilized aggregates from demolition solid waste as the pavement base layer. None of these patents mention the use of solid waste in the roadbed, and the proposed pavement structure schemes cannot simultaneously meet the requirements of heavy load resistance and self-reflective crack resistance. Since they do not use a high-strength roadbed, their longevity remains to be verified. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an inverted roadbed and pavement structure for comprehensive utilization of solid waste, so as to ensure that various types of solid waste can be comprehensively utilized on a large scale, and at the same time meet the demand for the use of long-life pavements on high-grade roads, so as to solve the shortcomings of the existing technology.

[0005] In order to achieve the above object, the purpose of the present invention is achieved through the following technical solutions:

[0006] Provided is an inverted roadbed and pavement structure for comprehensive utilization of solid waste, comprising an upper embankment filled with recycled aggregates of demolition solid waste, which is paved in sequence from bottom to top on the foundation of a lower embankment of a road, a roadbed paved with cement-desulfurized slag-gypsum composite stabilized engineering slag, a pavement subbase paved with desulfurized gypsum-cement stabilized recycled aggregates of demolition solid waste, an upper pavement base paved with graded crushed stone of recycled aggregate from waste concrete, a pavement lower layer and middle surface layer paved with factory-mixed hot-recycled SBS modified asphalt mixture, an upper layer paved with semi-flexible pavement material, and an asphalt wearing course paved with a high-viscosity modified asphalt mixture; the pavement lower layer and the middle surface layer, as well as the middle surface layer and the upper layer, are connected by a modified emulsified asphalt tack coat, and a high-elasticity modified asphalt stress absorption layer is paved between the pavement subbase and the pavement upper base.

[0007] For example, in the inverted roadbed and pavement structure for comprehensive utilization of solid waste, the uneven coefficient C of the recycled aggregate of the upper embankment is u In the range of 10 to 50.

[0008] For example, in the solid waste comprehensive utilization inverted roadbed and pavement structure, the bearing ratio CBR value of the composite stabilized engineering slag of the roadbed is not less than 10%.

[0009] For example, in the inverted roadbed and pavement structure for comprehensive utilization of solid waste, the mass percentage of desulfurized gypsum in the base layer of the pavement is 30% of the cement.

[0010] For example, in the inverted roadbed and pavement structure for comprehensive utilization of solid waste, the crushing value of the recycled aggregate graded crushed stone on the base layer of the pavement is not less than 40%.

[0011] In the inverted roadbed and pavement structure for comprehensive utilization of solid waste, the semi-flexible pavement material of the upper layer is completed by grouting cement-based slurry in large-void asphalt mixture, and the dynamic stability of the semi-flexible pavement material at 70°C is not less than 30,000 times·mm -1 .

[0012] For example, in the inverted roadbed and pavement structure for comprehensive utilization of solid waste, the thickness of the asphalt film on the surface of the stone particles in the high-viscosity modified asphalt mixture of the asphalt wearing layer is 15 to 20 μm.

[0013] As for the inverted roadbed and pavement structure for comprehensive utilization of solid waste, the structural layer thickness of the upper embankment is 70 cm, the thickness of the roadbed is 80 cm, the thickness of the pavement subbase is 30 to 40 cm, the thickness of the pavement upper base is 18 to 20 cm, the thickness of the pavement lower layer is 8 to 9 cm, the thickness of the middle surface layer is 6 to 7 cm, the thickness of the upper layer is 4 to 5 cm, and the thickness of the asphalt wearing layer is 1 to 2 cm.

[0014] This pavement structure, while ensuring a long service life, high driving safety and comfort, achieves the maximum comprehensive utilization of various types of solid waste, including demolition and construction solid waste, construction debris, industrial solid waste, and road surface recycled materials, in the subgrade and pavement structure. It meets the requirements for high-quality and high-quality projects under the background of dual carbon and ecological green development. Compared with the existing technology, the beneficial technical effects of this invention are specifically manifested in:

[0015] 1. The present invention adopts a roadbed paved with cement-slag-desulfurized gypsum composite stabilized engineering slag. The cement-slag-desulfurized gypsum undergoes a hydration reaction, which not only enhances the strength of the roadbed but also makes the roadbed slightly expansive, thereby enhancing its crack resistance. The increased roadbed strength is conducive to improving the overall strength of the pavement structure and extending its service life.

[0016] 2. The present invention effectively solves the problem of surface reflective cracks caused by shrinkage deformation of the semi-rigid base by laying a graded crushed stone flexible base on the semi-rigid base. At the same time, a stress absorption layer is provided between the semi-rigid base and the flexible base to avoid stress concentration caused by shrinkage deformation of the semi-rigid base, further enhancing the pavement structure's ability to prevent reflective cracks, thereby helping to extend the service life of the pavement.

[0017] 3. The present invention lays an asphalt wearing course on the upper surface of the semi-flexible pavement, thereby ensuring that the upper surface of the pavement has the ability to resist vehicle loads, while improving the driving comfort of the pavement, and also facilitating maintenance and repair in the later operation stage, thereby achieving rapid repair of the pavement's anti-skid performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To further illustrate the above-mentioned objectives, structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the overall structure of a preferred embodiment of the present invention;

[0020] In the figure: 1. Upper road embankment; 2. Roadbed; 3. Pavement subbase; 4. Pavement upper base; 5. Pavement lower layer; 6. Middle surface layer; 7. Upper layer; 8. Asphalt wearing layer; 9. Modified emulsified asphalt tack coat; 10. Highly elastic modified asphalt stress absorption layer. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0022] See Figure 1 As shown, the inverted roadbed and pavement structure for comprehensive utilization of solid waste according to the present invention comprises, from bottom to top, an upper embankment 1 constructed of recycled aggregate from demolition solid waste, laid on the foundation of the lower embankment; a roadbed 2 constructed of cement-desulfurized slag-gypsum composite stabilized engineering slag; a subbase 3 constructed of recycled aggregate from demolition solid waste stabilized with desulfurized gypsum-cement; an upper base 4 constructed of graded crushed stone from recycled aggregate from waste concrete; a lower pavement layer 5 and a middle pavement layer 6 constructed of factory-mixed hot-recycled SBS modified asphalt mixture; an upper pavement layer 7 constructed of semi-flexible pavement material; and an asphalt wearing course 8 constructed of a high-viscosity modified asphalt mixture. A modified emulsified asphalt tack coat 9 is used to connect the lower pavement layer 5 and the middle pavement layer 6, as well as the middle pavement layer 6 and the upper pavement layer 7. A high-elasticity modified asphalt stress absorption layer 10 is laid between the lower pavement layer 3 and the upper pavement layer 4.

[0023] Continuing to refer to the figure, in a preferred embodiment, the thickness of the structural layer of the upper embankment 1 is 70 cm, and the unevenness coefficient C of the recycled aggregate of the upper embankment 1 is u In the range of 10 to 50, the optimal value is 35.

[0024] The thickness of the roadbed 2 is 80 cm, and the bearing ratio CBR value of the composite stabilized engineering slag of the roadbed 2 is not less than 10%, and the optimal value is 32%.

[0025] The thickness of the road subbase 3 is 30-40 cm, preferably 40 cm. The amount of desulfurized gypsum used is 1.5% of the total mass of the composite stabilized recycled aggregate, and the amount of cement used is 5% of the total mass of the composite stabilized recycled aggregate.

[0026] The thickness of the road base 4 is 18 to 20 cm, the mass percentage of desulfurized gypsum in the road base 4 to cement is 30%, and the crushing value of the recycled aggregate graded gravel in the road base 4 is not less than 40%, and optimally not less than 50%.

[0027] The thickness of the lower pavement layer 5 is 8-9 cm, with an optimal value of 8 cm. The thickness of the middle surface layer 6 is 6-7 cm, with an optimal value of 6 cm. The technical performance of the factory-mixed hot-recycled SBS modified asphalt mixture in the lower pavement layer 5 and the middle surface layer 6 meets the technical requirements for SBS modified asphalt mixtures in the current specification "Technical Specification for Highway Asphalt Pavement Construction" (JTG F40-2004). The specific technical performance is shown in the following table:

[0028] Technical indicators Measured value Specification requirements <![CDATA[Dynamic stability (times·mm -1 )]]> 4500 ≥2800 Residual strength ratio of freeze-thaw splitting test (%) 90 ≥80 Low temperature bending test failure strain (με) 3500 ≥3000

[0029] The thickness of the upper layer 7 is 4 to 5 cm, preferably 4 cm. The semi-flexible pavement material of the upper layer 7 is made by grouting cement-based slurry in a large-void asphalt mixture. The void ratio of the asphalt mixture is 25%. The dynamic stability of the semi-flexible pavement material at 70°C is not less than 30,000 times·mm -1 , the optimal value is 40000 times·mm -1 .

[0030] The thickness of the asphalt wearing layer 8 is 1-2 cm, preferably 1 cm. The thickness of the asphalt film on the surface of the stone particles in the high-viscosity modified asphalt mixture of the asphalt wearing layer 8 is 15-20 μm, preferably 18 μm.

[0031] The present invention adopts a roadbed paved with cement-slag-desulfurized gypsum composite stabilized engineering slag. The cement-slag-desulfurized gypsum undergoes a hydration reaction, which on the one hand enhances the strength of the roadbed, and on the other hand makes the roadbed slightly expansive, thereby enhancing the roadbed's resistance to cracking. The increase in roadbed strength is beneficial to improving the overall strength of the pavement structure and extending its service life. The present invention effectively solves the problem of surface reflective cracks caused by shrinkage deformation of the semi-rigid base layer by laying a graded crushed stone flexible base layer on the semi-rigid base layer. At the same time, a stress absorption layer is provided between the semi-rigid base layer and the flexible base layer to avoid stress concentration caused by shrinkage deformation of the semi-rigid base layer, further enhancing the pavement structure's ability to prevent reflective cracks, and thereby contributing to extending the service life of the pavement. The present invention lays an asphalt wear layer on the upper layer of the semi-flexible pavement, thereby ensuring that the upper layer of the pavement has the ability to resist vehicle loads, while improving the driving comfort of the pavement, and also facilitating maintenance and repair in the later operation stage, thereby achieving rapid repair of the pavement's anti-skid performance.

[0032] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A solid waste comprehensive utilization inverted roadbed and pavement structure, characterized in that: The invention comprises an upper embankment filled with recycled aggregates of demolition solid wastes, which is paved in sequence from bottom to top on the foundation of the lower embankment of the road; a roadbed paved with cement-desulfurized slag-gypsum composite stabilized engineering slag; a road subbase paved with desulfurized gypsum-cement stabilized recycled aggregates of demolition solid wastes; a road upper base paved with graded crushed stone of recycled aggregates of waste concrete; a road lower layer and a middle surface layer paved with factory-mixed hot recycled SBS modified asphalt mixture; an upper layer paved with semi-flexible pavement material; and an asphalt wearing course paved with a high-viscosity modified asphalt mixture; between the road lower layer and the middle surface layer, and between the The middle surface layer and the upper layer are both connected by a modified emulsified asphalt tack coat, and a high-elasticity modified asphalt stress absorption layer is laid between the pavement subbase and the pavement upper base; the unevenness coefficient Cu of the recycled aggregate of the upper embankment is in the range of 10 to 50, the bearing ratio CBR value of the composite stabilized engineering slag of the roadbed is not less than 10%, the mass percentage of desulfurized gypsum in the pavement upper base to cement is 30%, the semi-flexible pavement material of the upper layer is completed by grouting cement-based slurry in large-void asphalt mixture, and the 70°C dynamic stability of the semi-flexible pavement material is not less than 30,000 times·mm-1.

2. The inverted roadbed and pavement structure for comprehensive utilization of solid waste according to claim 1, characterized in that: The crushing value of the recycled aggregate graded crushed stone on the base layer of the pavement is not less than 40%.

3. The inverted roadbed and pavement structure for comprehensive utilization of solid waste according to claim 1, characterized in that: The thickness of the asphalt film on the surface of the stone particles in the high-viscosity modified asphalt mixture of the asphalt wearing layer is 15-20 μm.

4. The inverted roadbed and pavement structure for comprehensive utilization of solid waste according to claim 1, characterized in that: The thickness of the structural layer of the upper embankment is 70 cm, the thickness of the roadbed is 80 cm, the thickness of the pavement subbase is 30~40 cm, the thickness of the pavement upper base is 18~20 cm, the thickness of the pavement lower layer is 8~9 cm, the thickness of the middle surface layer is 6~7 cm, the thickness of the upper layer is 4~5 cm, and the thickness of the asphalt wearing layer is 1~2 cm.

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