An antireflection crack modified asphalt pavement structure

Abstract

The utility model discloses a kind of anti-reflection crack modified asphalt pavement structures, it is related to pavement construction technical field, the anti-reflection crack modified asphalt pavement structure, including modified asphalt wearing course, anti-crack modified asphalt intermediate course, stress absorption layer, cement stabilized macadam base course, graded broken stone bottom base course and soil base arranged from top to bottom, the top surface of the absorption layer is equipped with several trapezoidal grooves along transverse interval distribution, trapezoidal groove fills flexible modified asphalt mastic, for absorbing and dispersing stress concentration from base layer.This utility model is by setting trapezoidal groove, grid fiber reinforced belt, sawtooth interface, anti-crack transition layer and antifreeze temperature insulation cushion layer and other multistage collaborative structure, form the composite anti-crack system that is integrated with stress release, absorption, enhancement and antifreeze, effectively inhibit the generation and expansion of reflection crack, significantly improve the durability and overall performance of cold region asphalt pavement.

Description

Technical Field

[0001] This utility model relates to the field of road construction technology, and in particular to an anti-reflective crack modified asphalt pavement structure. Background Technology

[0002] In some high-altitude and cold regions, asphalt pavements have long faced severe durability challenges. Some areas have a cold temperate continental monsoon climate with long and cold winters, with extreme low temperatures reaching below -30°C, and relatively hot and humid summers with an annual temperature difference of over 60°C. Coupled with the widespread distribution of seasonally frozen soil, the pavement structure is prone to cracking under repeated freeze-thaw cycles and drastic temperature gradient changes. More notably, cement-stabilized crushed stone base courses often develop transverse microcracks under the effects of construction drying shrinkage and temperature shrinkage. Under the combined action of traffic loads and environmental factors, the stress in these cracks accumulates upwards, gradually reflects upwards, and penetrates the asphalt surface layer, forming typical "reflective cracks".

[0003] Such cracks not only affect the smoothness of the road surface and driving comfort, but also accelerate water infiltration, causing a series of problems such as softening of the base layer, mud pumping, and frost heave, which seriously shortens the service life of the road.

[0004] Current conventional prevention and control measures mostly focus on material modification, such as using SBS-modified asphalt and adding fibers. While these measures improve the low-temperature crack resistance of asphalt mixtures to some extent, they have limited intervention in structural stress transfer and cannot fundamentally block the propagation path of reflective cracks. Some projects have attempted to use geogrids for reinforcement, but problems such as poor interlayer bonding and stress concentration at grid nodes have emerged. Utility Model Content

[0005] This utility model provides a modified asphalt pavement structure for resisting reflective cracking, comprising, from top to bottom, a modified asphalt wearing course, a crack-resistant modified asphalt intermediate course, a stress-absorbing course, a cement-stabilized crushed stone base course, a graded crushed stone subbase course, and a subgrade. The top surface of the absorption course is provided with several trapezoidal grooves distributed laterally, and the trapezoidal grooves are filled with flexible modified asphalt rubber to absorb and disperse stress concentration from the base course.

[0006] Preferably, the width of the trapezoidal groove is 5-10cm and the depth is 2-4cm, forming a periodic stress relief unit.

[0007] Preferably, a mesh fiber reinforcement strip is embedded in the top surface of the stress-absorbing layer along the transverse direction. The mesh fiber reinforcement strip is a polyester fiber woven strip, and the mesh fiber reinforcement strip is arranged alternately with the trapezoidal groove.

[0008] Preferably, a sawtooth interface structure is provided on the top surface of the cement-stabilized crushed stone base layer. The tooth height of the sawtooth interface is 1-3cm and the tooth spacing is 10-20cm. The bottom of the stress-absorbing layer is engaged with the sawtooth interface.

[0009] Preferably, a crack-resistant transition layer is provided between the cement-stabilized crushed stone base course and the graded crushed stone subbase course. The crack-resistant transition layer is a lean cement concrete layer with added short-cut fibers, with a thickness of 5 to 8 cm. Its surface is provided with shallow pit texture to inhibit the upward development of shrinkage cracks in the base course.

[0010] Preferably, a high-viscosity, high-toughness modified emulsified asphalt bonding layer is sprayed between the modified asphalt wearing layer and the crack-resistant modified asphalt intermediate layer, and the bonding layer thickness is 0.3 to 0.6 kg / m².

[0011] Preferably, an antifreeze and heat-insulating layer is laid on top of the soil base. The antifreeze and heat-insulating layer is made of molded polystyrene foam board with a thickness of 10-15cm to reduce the frost depth.

[0012] Preferably, the stress-absorbing layer has a thickness of 2 to 4 cm, and its mixture contains polyacrylonitrile fibers or basalt fibers with a length of 6 to 12 mm, with the fiber content being 0.2% to 0.4% of the total mass of the asphalt mixture.

[0013] Preferably, the modified asphalt wearing course is made of SBS modified asphalt mixture with a thickness of 3-5 cm, and the crack-resistant modified asphalt intermediate course is made of asphalt mixture with added rubber powder and SBS composite modification with a thickness of 5-7 cm.

[0014] Preferably, the cement-stabilized crushed stone base course is mixed with an antifreeze agent and a micro-expansion agent.

[0015] This utility model provides an anti-reflective crack modified asphalt pavement structure, which, compared with the prior art, offers the following advantages: 1. This utility model forms periodic stress release units by setting several trapezoidal grooves distributed laterally on the top surface of the stress absorption layer and filling the grooves with flexible modified asphalt rubber. This effectively cuts off the upward reflection path of base layer cracks. When microcracks are generated in the cement-stabilized crushed stone base layer due to temperature changes or drying shrinkage, the stress is interrupted by the trapezoidal groove structure during the upward transmission through the sawtooth interface. The flexible filling material undergoes coordinated deformation, absorbing and dispersing stress concentration, significantly delaying the initiation and expansion of reflective cracks. At the same time, the trapezoidal grooves and the mesh fiber reinforcement strip are arranged alternately to form a "release-reinforcement" composite mechanism, which allows local deformation while maintaining the tensile strength of the overall structure, greatly improving the crack resistance and durability of the pavement under repeated freeze-thaw cycles and temperature gradient changes in cold regions.

[0016] 2. This utility model adopts a multi-level synergistic crack-resistant design, which inhibits the development of reflective cracks from both structural and material dimensions. The sawtooth interface structure enhances the interlocking effect between the base layer and the stress-absorbing layer, and improves the uniformity of stress transmission between layers. The short-cut fibers and surface pit texture in the crack-resistant transition layer effectively inhibit the penetration of shrinkage cracks in the base layer. The anti-freeze and heat-insulating cushion layer reduces the freezing depth and uneven frost heave from the source, reducing the causes of cracking. The above structure, together with the modified asphalt layer and the high-bonding layer, constitutes a complete anti-reflective cracking system, which not only improves the deformation adaptability of the pavement structure, but also enhances the synergistic working performance between layers. It is especially suitable for areas such as Harbin with severe winters, large temperature differences, and frequent freeze-thaw cycles. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model; Figure 2 This is a cross-sectional view of the overall structure of an embodiment of the present utility model; Figure 3 This is a top view schematic diagram of the stress-absorbing layer structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the mesh fiber reinforced tape structure according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the meshing state of the sawtooth structure according to an embodiment of the present utility model; Figure 6 This is a schematic diagram of the antifreeze and heat insulation pad structure according to an embodiment of the present utility model; Figure 7 This is a schematic diagram of the crack-resistant transition layer structure according to an embodiment of the present invention.

[0019] Figure label: 1. Modified asphalt wearing course; 2. Crack-resistant modified asphalt intermediate course; 3. Stress-absorbing course; 4. Cement-stabilized crushed stone base course; 5. Graded crushed stone subbase course; 6. Subgrade; 7. Trapezoidal groove; 8. Fiber mesh reinforcement strip; 9. Serrated; 10. Antifreeze and heat insulation layer; 11. Crack-resistant transition layer. Detailed Implementation

[0020] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0021] Please refer to Figure 1 and Figure 2 This utility model provides a modified asphalt pavement structure with anti-reflective cracking, which includes a modified asphalt wearing course 1, an anti-crack modified asphalt intermediate course 2, a stress absorbing course 3, a cement-stabilized crushed stone base course 4, a graded crushed stone subbase course 5, and a subgrade 6 arranged from top to bottom. The structural layers are connected by functional interfaces to form a complete, coordinated, and crack-resistant composite system.

[0022] Among them, the modified asphalt wearing course 1 uses SBS modified asphalt mixture with a thickness of 3-5cm. It has excellent high temperature stability, anti-aging performance and anti-skid performance, and can effectively resist the shearing effect of wheels and ultraviolet aging.

[0023] The crack-resistant modified asphalt intermediate layer 2 uses asphalt mixture modified with rubber powder and SBS, with a thickness of 5-7cm. The introduction of rubber powder significantly improves the elasticity and low-temperature ductility of the asphalt binder, so that it still has good crack resistance below -20℃, and is suitable for extreme low temperature environments in cold regions during winter.

[0024] like Figure 6 As shown, a high-viscosity and toughness modified emulsified asphalt bonding layer is sprayed between the modified asphalt wearing course 1 and the crack-resistant modified asphalt intermediate course 2. The spraying amount is 0.3-0.6 kg / m². This bonding layer not only enhances the interlayer bonding strength and prevents interlayer slippage and voids, but its high toughness characteristics can also absorb some of the interlayer shear stress, further delaying crack propagation.

[0025] like Figure 3 As shown, the stress-absorbing layer 3 has a thickness of 2-4 cm and is made of asphalt mixture with polyacrylonitrile fibers or basalt fibers of 6-12 mm in length. The fibers form a three-dimensional network structure in the mixture, which significantly improves the tensile strength, fatigue resistance and post-cracking ductility of the material. More importantly, the top surface of the stress-absorbing layer 3 is provided with several trapezoidal grooves 7 distributed laterally along the road. Each trapezoidal groove 7 runs through the entire width of the road surface, and the center-to-center distance between adjacent trapezoidal grooves 7 is 15-30 cm, forming a periodic stress release zone.

[0026] The trapezoidal groove 7 has a groove width of 5-10cm, a depth of 2-4cm, and an angle of 60°-75° between the groove wall and the bottom surface, forming a standard trapezoidal cross section. The groove is filled with flexible modified asphalt rubber (such as high-elasticity rubber asphalt or TPS modified asphalt). This rubber has high ductility (ductility > 40cm at 5℃) and good low-temperature performance. It can achieve coordinated flow and elastic recovery when the base layer has minor cracks or uneven deformation, absorb and disperse the stress concentration transmitted upward, and effectively block the direct upward extension path of reflective cracks.

[0027] like Figure 4As shown, a mesh fiber reinforcement strip 8 is embedded on the top surface of the stress-absorbing layer 3, in the area between adjacent trapezoidal grooves 7. The mesh fiber reinforcement strip 8 is woven from polyester fiber and is mesh-shaped (preferably with a mesh size of 20cm×20cm~30cm×30cm) with a width of 5~8cm. It is laid in the transverse direction and anchored in the asphalt layer. The mesh fiber reinforcement strip 8 and the trapezoidal grooves 7 are arranged in an alternating manner on the plane to form a "groove-strip" composite structure: the groove area allows local deformation to release stress, while the reinforcement strip area provides continuous tensile stiffness. The two work together to achieve a crack-resistant mechanism of "local flexible release + overall rigid constraint", avoiding the problem of overall strength reduction caused by a single flexible structure.

[0028] like Figure 5 As shown, a sawtooth 9-shaped interface structure is prefabricated on the top surface of the cement-stabilized crushed stone base layer 4. The tooth height of the sawtooth 9-shaped structure is 1-3cm and the tooth spacing is 10-20cm. It is milled or prefabricated after the base layer is cured and shaped by a special mold. When the stress absorption layer 3 is paved, the bottom is embedded in the sawtooth 9-shaped interface to form a mechanical interlock, which significantly enhances the interlayer shear resistance, improves the uniformity of stress transmission, prevents interlayer slippage, and disperses the concentrated stress to multiple toothed units, reducing the local stress peak.

[0029] like Figure 7 As shown, a crack-resistant transition layer 11 is set between the cement-stabilized crushed stone base course 4 and the graded crushed stone subbase course 5. The crack-resistant transition layer 11 is made of lean cement concrete with added short-cut polypropylene fibers (0.1% to 0.3%), with a thickness of 5 to 8 cm and a cement content controlled at 80 to 120 kg / m³ to reduce the risk of hydration heat and drying shrinkage cracking. Its surface is formed with shallow pit texture (0.5 to 1.0 cm deep) by roughening or embossing process. On the one hand, it increases the mechanical interlocking with the upper base course, and on the other hand, it induces the uniform release of shrinkage stress through the distribution of micro-defects, inhibiting the formation and penetration of large-scale shrinkage cracks.

[0030] like Figure 6 As shown, an antifreeze and heat insulation layer 10 is laid on top of the subgrade 6. It is made of molded polystyrene foam board with a density of 20-30 kg / m³ and a thickness of 10-15 cm. The antifreeze and heat insulation layer 10 has a low thermal conductivity, which can effectively block the downward transfer of cold from the ground surface, significantly reduce the seasonal freezing depth, prevent road surface heave and cracking caused by uneven freezing and swelling of the subgrade 6, and reduce the inducing factors of reflective cracks from the source.

[0031] In addition, the graded crushed stone subbase 5 adopts a dense gradation with a maximum particle size of no more than 37.5 mm and a compaction degree of no less than 98%, which has both good bearing capacity and drainage performance, and avoids water accumulation that leads to softening of the base layer.

[0032] In summary, firstly, trapezoidal grooves 7 are set on the top surface of the stress-absorbing layer 3, filled with flexible modified asphalt adhesive to absorb and disperse the stress generated by the base course cracks and block the reflection path. Secondly, the mesh fiber reinforcement strips 8 are arranged alternately with the trapezoidal grooves to provide local deformation release and overall rigid constraint, enhancing crack resistance. The top surface of the cement-stabilized crushed stone base course 4 has a pre-fabricated sawtooth 9-shaped interface to enhance interlayer bonding and uniformly transfer stress. A crack-resistant transition layer 11 is set between the base course and the subbase course, with shallow pit texture on the surface inducing uniform release of shrinkage stress. An anti-freeze and heat-insulating cushion layer 10 is laid on top of the subgrade 6 to reduce the impact of frost heave. All layers are tightly connected by a high-viscosity and toughness modified emulsified asphalt bonding layer to ensure interlayer stability and synergistically improve pavement durability and anti-reflective cracking ability.

[0033] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A modified asphalt pavement structure resistant to reflective cracking, characterized in that: The structure includes, from top to bottom, a modified asphalt wear layer (1), a crack-resistant modified asphalt intermediate layer (2), a stress-absorbing layer (3), a cement-stabilized crushed stone base course (4), a graded crushed stone subbase course (5), and a soil base course (6). The stress-absorbing layer (3) has several trapezoidal grooves (7) spaced laterally on its top surface. The trapezoidal grooves (7) are filled with flexible modified asphalt adhesive to absorb and disperse stress concentration from the base course.

2. The anti-reflective cracking modified asphalt pavement structure according to claim 1, characterized in that: The trapezoidal groove (7) has a groove width of 5-10cm and a depth of 2-4cm, forming a periodic stress relief unit.

3. The anti-reflective cracking modified asphalt pavement structure according to claim 2, characterized in that: The stress-absorbing layer (3) has a mesh fiber reinforcement strip (8) embedded in the transverse direction on its top surface. The mesh fiber reinforcement strip (8) is a polyester fiber woven strip, and the mesh fiber reinforcement strip (8) and the trapezoidal groove (7) are arranged alternately.

4. The anti-reflective cracking modified asphalt pavement structure according to claim 3, characterized in that: A sawtooth (9) shaped interface structure is provided on the top surface of the cement-stabilized crushed stone base (4). The tooth height of the sawtooth (9) shaped interface is 1-3cm and the tooth spacing is 10-20cm. The bottom of the stress absorption layer (3) is engaged with the sawtooth (9) shaped interface.

5. The anti-reflective cracking modified asphalt pavement structure according to claim 1, characterized in that: A high-viscosity, high-toughness modified emulsified asphalt bonding layer is sprayed between the modified asphalt wear layer (1) and the crack-resistant modified asphalt intermediate layer (2), with a bonding layer thickness of 0.3 to 0.6 kg / m².

6. The anti-reflective cracking modified asphalt pavement structure according to claim 5, characterized in that: An antifreeze and heat insulation layer (10) is laid on top of the soil base (6). The antifreeze and heat insulation layer (10) is made of molded polystyrene foam board with a thickness of 10-15cm, which is used to reduce the freezing depth.

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