Rigid-flexible fusion asphalt pavement structure for blackening reconstruction of old cement pavement

Abstract

The utility model relates to the technical field of highway reconstruction, specifically relates to a kind of rigid-flexible fusion asphalt pavement structure for old cement road white plus black reconstruction, from bottom to top include semi-rigid bottom base course, flexible cement concrete base course and asphalt concrete surface course in turn.Rigid-flexible fusion asphalt pavement structure enhances the structural synergy between asphalt surface course and old cement pavement, improves the adaptability to hidden disease of old pavement, improves the service life of road after white plus black reconstruction, and reduces the maintenance cost in later period.

Description

Technical Field

[0001] This utility model relates to the field of highway reconstruction technology, specifically to a rigid-flexible asphalt pavement structure for the white-to-black renovation of old cement roads. Background Technology

[0002] The "white-to-black" renovation of old cement roads refers to the technique of treating the old cement concrete pavement (white pavement) and then laying an asphalt concrete surface layer (black pavement). This method can utilize the structural strength of the original cement pavement while improving the driving comfort, and is a commonly used, economical, and effective means of upgrading and renovating old roads.

[0003] However, due to the differences in mechanical properties between old cement concrete pavement and asphalt concrete pavement, problems such as interface delamination and localized settlement can easily occur when there is poor interfacial bonding or uncoordinated stress. For example, if the surface of the old pavement is not thoroughly cleaned, a sliding interface will form between the asphalt layer and the cement slab, causing shoving and bumping when vehicles brake or accelerate. The effect of the white-to-black pavement renovation is highly dependent on the original condition of the old cement pavement. If the inspection and evaluation are not thorough or the defects are not properly treated, hidden dangers can easily be left behind, and even a chain reaction of secondary defects can occur.

[0004] The fundamental flaw in the "white-plus-black" pavement reconstruction lies in the challenge of synergistic integration between the rigid base layer and the flexible surface layer, as well as the mismatch between the hidden dangers of the old pavement and the performance of the new structure. Although existing technologies have mitigated the chain reaction caused by secondary defects to some extent by assessing the types of defects before reconstruction and strengthening construction quality control, the post-reconstruction pavement performance still falls short of meeting the requirements for long-life highways. Summary of the Invention

[0005] The purpose of this utility model is to provide a road surface structure for the upgrading and renovation of old cement roads, so as to enhance the structural synergy between the asphalt surface layer and the old cement road surface, improve the adaptability to the hidden defects of the old road surface, extend the service life of the road surface after the asphalt-to-asphalt renovation, and reduce the later maintenance costs.

[0006] To achieve the above objectives, this utility model proposes a rigid-flexible asphalt pavement structure for the renovation of old cement roads, which includes, from bottom to top, a semi-rigid subbase, a flexible cement concrete base, and an asphalt concrete surface layer. The flexible cement concrete base course is constructed to utilize impact energy to crack the semi-rigid pavement of the old cement road. The resilient modulus of the flexible cement concrete base layer is comparable to that of the asphalt concrete surface layer, which enables the flexible cement concrete base layer and the asphalt concrete surface layer to be effectively integrated into one, jointly bearing load and coordinating deformation. The top of the flexible cement concrete base layer is milled to form a transition layer for enhancing the fusion with the asphalt concrete surface layer. The transition layer is configured to form an implantation groove on the top of the flexible cement concrete base layer by milling.

[0007] The flexible cement concrete base layer is milled 1cm-3cm from the top to form an uneven, exposed aggregate of gravel and cement stone. Hot asphalt is then spread on it to give it the characteristics of an asphalt mixture. This aggregate is then interlocked and bonded with the overlaid asphalt concrete surface layer to form a rigid-flexible transition layer. This allows the upper and lower layers to merge into one, share the load, and deform together.

[0008] Preferably, the flexible cement concrete base course includes a surface layer and a cracked layer. The surface layer is located above the cracked layer and is used to construct a transition layer. The surface layer is provided with contact areas for transmitting impact energy. The surface layer is configured to use the contact areas to transmit impact energy to the cracked layer. The cracked layer is configured to generate oblique cracks from bottom to top under the action of impact energy, thus forming a flexible treatment for the semi-rigid pavement.

[0009] As a preferred option, 1kg-2kg of hot ordinary asphalt, modified asphalt, or high-viscosity, high-elasticity asphalt is sprayed per square meter on the transition layer, and crushed stone with a particle size of 1cm-2cm and pre-coated with 3‰-5‰ asphalt is spread on it.

[0010] As a preferred option, the cracking rate of the cracked layer reaches more than 80%, which makes the resilient modulus of the flexible cement concrete base layer between 1000MPa and 2000MPa.

[0011] Preferably, the contact area is distributed in a quincunx pattern on the surface.

[0012] As a preferred option, the semi-rigid subbase is composed of cement-stabilized crushed stone, and the thickness of the semi-rigid subbase is 18cm-46cm.

[0013] As a preferred option, the thickness of the asphalt concrete pavement is 3cm-18cm.

[0014] The rigid-flexible asphalt pavement structure provided by this utility model for the white-to-black renovation of old cement roads has the following substantial features and advancements compared with existing technologies: This rigid-flexible asphalt pavement structure, used for the white-to-black renovation of old cement roads, utilizes a flexible cement concrete base layer as a transitional core layer connecting the subbase and surface layer. It retains the load-bearing capacity of cement concrete while gaining adaptable deformation capacity through flexible treatment, becoming key to coordinating the stress on the upper and lower layers. Since the resilient modulus of the flexible cement concrete base layer is comparable to that of the asphalt concrete surface layer, the two can effectively integrate into a cohesive whole structure. Under the action of external forces such as vehicle loads, the load can be more evenly transmitted and distributed between the two layers, avoiding the stress concentration problem caused by excessive differences in elastic modulus in traditional structures. This significantly improves the load-bearing capacity and deformation resistance of the entire pavement structure, enhances the structural synergy between the asphalt surface layer and the old cement pavement, and improves the adaptability to hidden defects in the old pavement. Furthermore, by directly using impact energy to treat the semi-rigid pavement of the old cement road to form a flexible cement concrete base layer, it eliminates the complex steps of demolishing the old road and repaving the base layer in traditional renovations, extending the service life of the white-to-black pavement and reducing later maintenance costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a rigid-flexible asphalt pavement structure for the renovation of old cement roads using a combination of white and black asphalt pavement, as described in this utility model embodiment.

[0016] Figure 2 This is a schematic diagram of the flexible cement concrete base layer in an embodiment of this utility model.

[0017] Figure 3 This is a schematic diagram of a partial surface structure of the flexible cement concrete base layer in an embodiment of this utility model.

[0018] Reference numerals: 1. Subgrade; 2. Semi-rigid subbase; 3. Flexible cement concrete base course; 4. Asphalt concrete surface course; 5. Transition course; 31. Surface course; 32. Cracked course; 33. Contact area. Detailed Implementation

[0019] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0020] Currently, the fundamental shortcomings of asphalt pavement reconstruction lie in the challenge of synergistic integration between the rigid base layer and the flexible surface layer, as well as the mismatch between the hidden defects of the old pavement and the performance of the new structure. This utility model proposes a rigid-flexible asphalt pavement structure for asphalt-asphalt reconstruction of old cement roads, aiming to enhance the structural synergy between the asphalt surface layer and the old cement pavement, improve adaptability to hidden defects in the old pavement, extend the service life of the reconstructed pavement, and reduce subsequent maintenance costs.

[0021] like Figure 1As shown, a rigid-flexible asphalt pavement structure for the renovation of old cement roads includes, from bottom to top, a semi-rigid subbase 2, a flexible cement concrete base 3, and an asphalt concrete surface layer 4.

[0022] The flexible cement concrete base layer 3 is constructed to utilize impact energy to crack the semi-rigid pavement of the old cement road. The resilient modulus of the flexible cement concrete base layer 3 is comparable to that of the asphalt concrete surface layer 4, which enables the flexible cement concrete base layer 3 and the asphalt concrete surface layer 4 to be effectively integrated into one, jointly bearing load and coordinating deformation. The top of the flexible cement concrete base layer 3 is milled and roughened to form a transition layer 5 for enhancing the integration with the asphalt concrete surface layer 4. The transition layer 5 is constructed to form an implantation groove on the top of the flexible cement concrete base layer by milling and roughening.

[0023] Therefore, the semi-rigid subbase 2, as the lowest structure, relies on the high strength, high stability and low deformation characteristics of semi-rigid materials to provide a solid foundation platform for the superstructure. Its core function is to disperse and transfer the superload to the subgrade 1, while resisting the vertical deformation caused by subgrade settlement, avoiding the overall structural damage caused by subgrade instability, and eliminating the hidden danger of surface cracking caused by foundation settlement from the root.

[0024] The flexible cement concrete base layer 3 serves as a transitional core layer connecting the subbase and the surface layer. It retains the load-bearing capacity of cement concrete and gains adaptable deformation capacity through flexible treatment, becoming the key to coordinating the stress on the upper and lower layers.

[0025] The asphalt concrete surface layer 4 is in direct contact with vehicle loads and the natural environment. Relying on the flexibility, anti-skid properties and sealing properties of asphalt materials, it provides a comfortable driving surface while blocking external factors such as water and temperature from eroding the base layer.

[0026] Meanwhile, the transition layer 5, formed by milling and roughening the top of the flexible cement concrete base layer 3 through the implantation groove, significantly increases the contact area between the base layer and the asphalt surface layer. During asphalt concrete paving, the molten asphalt can penetrate deep into the implantation groove, forming a mechanical interlocking structure, replacing the traditional method of relying solely on interface bonding, significantly improving the interlayer shear strength, and preventing interlayer slippage during vehicle braking or steering.

[0027] The core problem with traditional pavements is that the elastic modulus of rigid base layers and flexible surface layers differs greatly, usually by 10 to 20 times. This leads to severe stress concentration at the interface between the surface layer and the base layer under vehicle loads. The surface layer fatigues and cracks due to excessive bending, while the base layer develops reflective cracks due to rigid constraints, ultimately triggering a chain of defects.

[0028] Meanwhile, the flexible cement concrete base layer 3 undergoes controlled treatment of the rigid cement concrete using specialized cracking equipment, reducing its rebound modulus to a level comparable to that of the asphalt concrete surface layer 4. Under load, the surface layer and the base layer are no longer in a "hard-rigid-flexible" antagonistic relationship, but rather undergo simultaneous elastic deformation. The stress generated by the load is evenly distributed across the two layers, preventing local stress from exceeding the material limits. Furthermore, the similar moduli result in a more balanced stress distribution at the bonding interface between the two layers, reducing interfacial delamination caused by relative slippage. This allows the surface layer and the base layer to truly become a unified load-bearing unit, sharing the load.

[0029] Traditional pavement interlayer bonding relies on a single tack coat or primer coat, which is prone to interfacial delamination due to excessive shear stress. To address this issue, 1-2 kg of hot ordinary asphalt, modified asphalt, or high-viscosity, high-elasticity asphalt is applied per square meter to transition layer 5, along with crushed stone with a particle size of 1-2 cm pre-coated with 3‰-5‰ asphalt. The crushed stone coverage of transition layer 5 is 50%-70%.

[0030] like Figure 1 and Figure 2 As shown, the flexible cement concrete base layer 3 includes a surface layer 31 and a cracked layer 32. The surface layer 31 is located above the cracked layer 32 and is used to contact the asphalt concrete surface layer 4. Figure 3 As shown, a contact area 33 for transmitting the impact energy of a dedicated cracking device is provided on the surface layer 31.

[0031] The surface layer 31 is configured to transfer the impact energy of the special cracking equipment to the cracking layer 32 through the contact area 33; the cracking layer 32 is configured to generate oblique cracks from bottom to top under the action of impact energy, forming a flexible treatment of the rigid cement concrete base layer.

[0032] In this process, the surface layer 31 serves as an intermediate layer for energy transfer. Through a pre-defined contact area 33, it concentrates and uniformly introduces the impact energy from the specialized cracking equipment into the cracking layer 32, preventing the energy from being dissipated meaninglessly or overloaded locally in the surface layer 31. For example, the specialized cracking equipment generates impact energy through free fall.

[0033] The oblique cracking from bottom to top in the cracked layer 32 is a controllable directional micro-cracking. The cracks start at the bottom of the cracked layer 32 and extend obliquely upwards. This ensures the formation of a uniform micro-crack network inside the cracked layer 32 while strictly limiting the crack range. It prevents the cracks from penetrating the surface layer 31 and from affecting the semi-rigid subbase 2. This ensures that the rigid cement concrete base layer maintains its structural integrity while becoming flexible, avoiding strength reduction due to excessive fragmentation.

[0034] The cracked layer 32, with its energy-directed, regularly patterned crack system, significantly optimizes the structural stress. The diagonal cracks intersect with the vertical and horizontal stresses generated by vehicle loads, dispersing stress more efficiently. Under load, the cracks can absorb energy through minute displacements, preventing stress concentration in localized areas.

[0035] The contact area 33 serves as an energy input point, reducing the loss of impact energy during transmission. This ensures that every microcrack in the cracked layer 32 is driven by controllable energy, avoiding local over-cracking or under-cracking caused by traditional blind impacts and significantly improving the quality uniformity of the flexible treatment.

[0036] By pre-setting the location and density of the contact area 33, the degree of cracking can be adjusted according to the pavement design requirements, achieving customized solutions. Simultaneously, directional cracking reduces the vibration impact on surrounding structures and minimizes construction disruption to the surrounding environment.

[0037] like Figure 3 As shown, the contact areas 33 are distributed in a staggered pattern on the surface layer 31. The area of ​​each contact area 33 is greater than 140 cm². There are 3-6 contact areas 33 per square meter on the surface layer 31.

[0038] Therefore, compared to a row-and-column distribution, a staggered layout allows the contact area 33 to form a denser network of energy transfer nodes on the surface layer 31, ensuring that each area of ​​the cracked layer 32 is effectively covered by impact energy. Even in road sections with a wide road surface, it can avoid localized uncracked or over-cracked areas caused by uneven energy distribution, ensuring that the resilience modulus of the cracked layer 32 remains highly consistent throughout the entire road section.

[0039] The impact energy transmitted from adjacent contact areas 33 forms a superimposed stress field inside the cracked layer 32. The direction of the oblique cracks will become more regular due to this energy crossover, preventing the cracks from spreading disorderly due to energy disturbance, and further improving the structural stability of the cracked layer 32.

[0040] According to some preferred embodiments of the present invention, the cracking rate of the cracking layer 32 reaches more than 80%, so that the elastic modulus of the flexible cement concrete base layer 3 is between 1000MPa and 2000MPa.

[0041] According to some preferred embodiments of this utility model, the flexible cement concrete base layer 3 is made of cement concrete with a grade of C30 or higher. The thickness of the flexible cement concrete base layer 3 is 15cm-26cm. The semi-rigid subbase layer 2 is composed of cement-stabilized crushed stone. The thickness of the semi-rigid subbase layer 2 is 18cm-46cm.

[0042] Preferably, the asphalt concrete surface layer 4 is paved with a thickness of 3cm-18cm. The flexible cement concrete base layer 3 has cement concrete strips on both sides to ensure lateral stability of the road surface. The width of the cement concrete strips is 50cm-80cm, and the thickness is the same as that of the flexible cement concrete base layer 3.

[0043] This utility model is not limited to the specific technical solutions described in the above embodiments. Besides the above embodiments, this utility model may have other implementation methods. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A rigid-flexible asphalt pavement structure for the renovation of old cement roads using a combination of white and black asphalt, characterized in that, From bottom to top, it includes a semi-rigid subbase (2), a flexible cement concrete base (3), and an asphalt concrete surface layer (4). The flexible cement concrete base course (3) is constructed to utilize impact energy to crack the semi-rigid pavement of the old cement road. The resilient modulus of the flexible cement concrete base layer (3) is comparable to that of the asphalt concrete surface layer (4), which enables the flexible cement concrete base layer (3) and the asphalt concrete surface layer (4) to be effectively integrated into one, jointly bearing load and coordinating deformation. The top of the flexible cement concrete base layer (3) is milled to form a transition layer (5) for enhancing the integration with the asphalt concrete surface layer (4). The transition layer (5) is configured to form an implantation groove on the top of the flexible cement concrete base layer (3) by milling.

2. The rigid-flexible asphalt pavement structure for the white-to-black renovation of old cement roads according to claim 1, characterized in that, The flexible cement concrete base layer (3) includes a surface layer (31) and a cracked layer (32), wherein the surface layer (31) is located above the cracked layer (32) and is used to construct a transition layer (5). The surface layer (31) is provided with a contact area (33) for transmitting impact energy, and the surface layer (31) is configured to transmit impact energy to the cracking layer (32) using the contact area (33). The cracked layer (32) is configured to generate oblique cracks from bottom to top under the action of impact energy, forming a flexible treatment for the semi-rigid pavement.

3. The rigid-flexible asphalt pavement structure for the white-to-black renovation of old cement roads according to claim 2, characterized in that, The cracking rate of the cracked layer (32) reaches more than 80%, so that the elastic modulus of the flexible cement concrete base layer (3) is between 1000MPa and 2000MPa.

4. The rigid-flexible asphalt pavement structure for the white-to-black renovation of old cement roads according to claim 2, characterized in that, The contact area (33) is distributed in a plum blossom pile pattern on the surface layer (31).

5. The rigid-flexible asphalt pavement structure for the white-to-black renovation of old cement roads according to claim 1, characterized in that, The semi-rigid base course (2) is composed of cement-stabilized crushed stone, and the thickness of the semi-rigid base course (2) is 18cm-46cm.

6. The rigid-flexible asphalt pavement structure for the white-to-black renovation of old cement roads according to claim 1, characterized in that, The thickness of the asphalt concrete surface layer (4) is 3cm-18cm.

Images