Inverted asphalt pavement structure

Abstract

The utility model discloses an inverted asphalt pavement structure which comprises an improvement layer, a cushion layer, a hydraulic material processing layer, a stress diffusion middle layer, a subbase layer, a base layer and a surface layer which are sequentially paved from bottom to top, the thickness of the improved layer is 100 cm, and the improved layer is formed by paving sandy clay; the thickness of the cushion layer is 50cm, and the cushion layer is formed by paving sandy clay; the thickness of the hydraulic material treatment layer is 25cm, and the hydraulic material treatment layer is formed by paving 3%-5% cement improved soil; the thickness of the stress diffusion middle layer is 12 cm, and the stress diffusion middle layer is formed by paving graded broken stones with the particle size range of 0-20 mm; the thickness of the subbase layer is 9-10cm, and the subbase layer is formed by paving asphalt macadam; the base layer is formed by paving asphalt macadam; and the surface layer is formed by paving semi-open graded asphalt concrete.

Description

Technical Field

[0001] The utility model relates to the technical field of highway engineering, and particularly relates to an inverted asphalt pavement structure. Background Technique

[0002] In recent years, the construction of asphalt pavements in China has also shown a trend towards long-life asphalt pavements. However, China is not willing to completely abandon the semi-rigid base structure that has been used for a long time. Instead, it is more inclined to improve this structure. The inverted structure is one of the mainstream practices. The inverted structure refers to the inversion of the base layer, that is, using inorganic binder stabilized materials with higher stiffness in the sub-base layer, and using flexible graded crushed stone or asphalt stabilized materials in the base layer. In current relevant patents in China, the design of the inverted asphalt pavement structure mostly involves the inversion of the upper and lower layers inside the asphalt layer and the base layer. Substantially, it is still in the form of a semi-rigid base asphalt pavement structure, not a true inverted asphalt pavement structure. It also does not consider the need to set a seal layer on the graded crushed stone layer during construction in rainy weather, and lacks the design of the cushion layer and the improvement layer, and fails to fully display the inverted asphalt pavement structure, and cannot effectively solve the problem of reflective cracking of asphalt pavements.

[0003] Nowadays, in the project of assisting in the construction of Africa, Chinese enterprises need to follow French standards for road structure construction, and this premise is to be familiar with the pavement structure. The inverted asphalt pavement structure was proposed by France in 1988 to solve the problem of reflective cracks in semi-rigid bases. Therefore, in order to address the deficiencies of existing research results and effectively solve the problem of reflective cracking of semi-rigid base asphalt pavements, it is necessary to propose an inverted asphalt pavement structure based on French standards. Content of the Utility Model

[0004] In view of the above problems, the utility model provides an inverted asphalt pavement structure, which provides a true and complete inverted asphalt pavement structure. It not only solves the problem of easy reflective cracking of traditional semi-rigid base asphalt pavements, but also provides a solution for waterproofing during rainy season construction. At the same time, it can also provide reference for projects that need to follow French standards for the construction and design of inverted pavement structures.

[0005] To achieve the above purpose, the technical solution of the utility model is as follows.

[0006] An inverted asphalt pavement structure, characterized in that it includes an improvement layer, a cushion layer, a hydraulically hardened material treatment layer, a stress diffusion intermediate layer, a subbase course, a base course and a surface course paved in sequence from bottom to top; the thickness of the improvement layer is 100 cm and it is paved with sandy clay; the thickness of the cushion layer is 50 cm and it is paved with sandy clay; the thickness of the hydraulically hardened material treatment layer is 25 cm and it is paved with 3% - 5% cement-improved soil; the thickness of the stress diffusion intermediate layer is 12 cm and it is paved with graded crushed stone with a particle size range of 0 - 20 mm; the thickness of the subbase course is 9 - 10 cm and it is paved with asphalt macadam; the thickness of the base course is 9 cm and it is paved with asphalt macadam; the thickness of the surface course is 6 cm and it is paved with semi-open-graded asphalt concrete.

[0007] Preferably, the paving materials used in the improvement layer, the cushion layer, the hydraulically hardened material treatment layer, the stress diffusion intermediate layer, the subbase course, the base course and the surface course meet the French requirements. Among them, the asphalt in the asphalt mixture used for the subbase course, the base course and the surface course meets the requirements of asphalt grades 35 / 50 or 50 / 70 in NF EN 12591 standard, and the performance of the mineral aggregates meets the requirements in French specification NFP 18-545 and EN 13043.

[0008] Preferably, the anti-fatigue performance of the subbase course and the base course is better than that of the surface course and they have a load-bearing function.

[0009] Preferably, the CBR value of the material bearing capacity of the improvement layer and the cushion layer exceeds the domestic requirements for the same functional layer.

[0010] Preferably, a prime coat and a seal coat are successively arranged between the stress diffusion intermediate layer and the subbase course; the prime coat is paved with 0 / 1 grade diluted asphalt at a spraying dosage of 1 kg / m 2 ; the seal coat is mainly used to seal the voids on the surface of the stress diffusion intermediate layer to prevent water intrusion and damage caused by weather or vehicle action.

[0011] Preferably, an emulsified asphalt lower bonding layer is provided between the subbase course and the base course; an emulsified asphalt upper bonding layer is provided between the base course and the surface course; the emulsified asphalt lower bonding layer and the emulsified asphalt upper bonding layer are paved with cationic emulsified asphalt with a residual asphalt content ≥ 65% at a spreading amount ≥ 250 g / m 2 ;

[0012] Preferably, the organic matter content of the sandy clay used in the improvement layer is < 1.0%, the plasticity index ≤ 25, the liquid limit < 50, and the California bearing ratio ≥ 15.

[0013] Preferably, the organic matter content of the sandy clay used in the cushion layer is < 1.0%, the plasticity index ≤ 25, the liquid limit < 50, the California bearing ratio ≥ 20, and the secondary static deformation modulus EV2 ≥ 80 Mpa.

[0014] Preferably, the soil of the cement-improved soil used in the hydraulic material treatment layer is sandy clay or laterite aggregate; the organic matter content in the cement-improved soil used in the hydraulic material treatment layer is ≤ 0.5%, the plasticity index is < 20, and the sieve passing amount through 80μm is ≤ 20%.

[0015] Preferably, the compaction degree of the hydraulic material treatment layer is ≥ 98%, and the 7d CBR value is ≥ 150.

[0016] Preferably, the sieve passing amount through 80μm of the graded broken stone used in the stress diffusion intermediate layer is 4% - 9%, and the methylene blue value is < 0.1%.

[0017] Preferably, the asphalt dosage in the asphalt macadam used for the subbase and base course is ≥ 4.2%, and the abundance coefficient K is ≥ 2.8; the asphalt dosage in the semi-open graded asphalt concrete used for the surface course is ≥ 5.0%, and the abundance coefficient K is ≥ 3.2.

[0018] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0019] (1) The present utility model adopts an inverted asphalt pavement structure, that is, the stress diffusion intermediate layer and the hydraulic material treatment layer are inverted, with an asphalt macadam base course and an asphalt concrete surface course paved on the upper layer, and a cushion layer and an improvement layer paved on the lower layer. At the same time, the thicknesses of each layer of the pavement structure are reasonably set and suitable paving materials are selected. On the one hand, a cushion layer and an improvement layer are provided under the hydraulic material treatment layer, and the CBR value of the material properties of the cushion layer and the improvement layer is higher than the domestic requirements, which improves the overall bearing capacity of the pavement structure, realizes an effective transition with the subgrade, and can reduce the influence of uneven settlement of the subgrade; on the other hand, a stress diffusion intermediate layer is provided between the hydraulic material treatment layer and the asphalt layer to achieve a smooth connection of the pavement materials from semi-rigid to flexible, forming a state of combining rigidity and flexibility, which can effectively prevent the cracking of the hydraulic material treatment layer. In addition, the structural design conforms to the long-life pavement design concept, and a long-term usable base course can be provided, and only the surface course needs to be repaired during the road maintenance process.

[0020] (2) A pavement structure form provided by the present utility model not only enriches the experience of road pavement structure design in our country, but also enables the designers and constructors in our country to make full use of the advanced engineering construction technologies and engineering construction experiences in our country on the basis of understanding the French standards, which is conducive to the external popularization and application of the engineering construction technologies in our country. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a cross-sectional view of an inverted asphalt pavement structure of the present utility model;

[0022] The meanings of the various markings in the above figures are as follows: 1 - improvement layer, 2 - cushion layer, 3 - hydraulically bound material treatment layer, 4 - stress diffusion intermediate layer, 410 - prime coat, 420 - seal coat, 5 - subbase, 510 - emulsified asphalt lower bonding layer, 6 - base course, 610 - emulsified asphalt upper bonding layer, 7 - surface course. Detailed implementation manners

[0023] In order to make the objectives, implementation manners and advantages of the present utility model clearer, the present utility model will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0024] Embodiment

[0025] An inverted asphalt pavement structure, as Figure 1 shown, includes an improvement layer 1, a cushion layer 2, a hydraulically bound material treatment layer 3, a stress diffusion intermediate layer 4, a subbase 5, a base course 6 and a surface course 7 paved in sequence from bottom to top; a prime coat 410 and a seal coat 420 are successively provided between the stress diffusion intermediate layer 4 and the subbase 5; an emulsified asphalt lower bonding layer 510 is provided between the subbase 5 and the base course 6; an emulsified asphalt upper bonding layer 610 is provided between the base course 6 and the surface course 7;

[0026] Among them, the thickness of the improvement layer 1 is 100 cm, and it is paved with sandy clay. The organic matter content of the sandy clay is < 1.0%, the plasticity index ≤ 25, the liquid limit < 50, and the California bearing ratio ≥ 12;

[0027] The thickness of the cushion layer 2 is 50 cm, and it is paved with sandy clay. The organic matter content of the sandy clay is < 1.0%, the plasticity index ≤ 25, the liquid limit < 50, the California bearing ratio ≥ 20, and the secondary static deformation modulus EV2 ≥ 80 Mpa;

[0028] The thickness of the hydraulically bound material treatment layer 3 is 25 cm, and it is paved with 3% - 5% cement-improved soil. The soil quality of the cement-improved soil is sandy clay. The organic matter content of the sandy clay is < 1.0%, the plasticity index ≤ 25, the liquid limit < 50, the California bearing ratio ≥ 20, and the secondary static deformation modulus EV2 ≥ 80 Mpa; after construction, the compaction degree of the hydraulically bound material treatment layer 2 ≥ 98%, and the 7d CBR value ≥ 150;

[0029] The thickness of the stress diffusion intermediate layer 4 is 12 cm, and it is paved with graded crushed stone with a particle size range of 0 - 20 mm; the 80μm sieve passing rate of the graded crushed stone is 4% - 9%, and the methylene blue value < 0.1%;

[0030] The prime coat 420 is paved with 0 / 1 grade diluted asphalt at a spraying dosage of 1 kg / m 2 ;

[0031] The emulsified asphalt lower bonding layer 510 and the emulsified asphalt upper bonding layer 610 are paved by spraying cationic emulsified asphalt with a residual asphalt content of ≥ 65% at a spraying rate of ≥ 250 g / m 2 ;

[0032] The thickness of the subbase course 5 is 9 - 10 cm and it is paved with asphalt macadam; the thickness of the base course 6 is 9 cm and it is paved with asphalt macadam; the thickness of the surface course 7 is 6 cm and it is paved with semi-open graded asphalt concrete. The asphalt in the asphalt mixture used for the subbase course, base course and surface course meets the requirements of asphalt grades 35 / 50 or 50 / 70 in NF EN 12591 standard, and the properties of the mineral aggregate meet the requirements of French specification NFP 18 - 545 and EN 13043. The asphalt content in the asphalt macadam used for the subbase course 5 and base course 6 is ≥ 4.2%, and the abundance coefficient K ≥ 2.8. The asphalt content in the semi-open graded asphalt concrete used for the surface course 7 is ≥ 5.0%, and the abundance coefficient K ≥ 3.2.

[0033] The construction method of the inverted asphalt pavement structure of the present utility model is as follows: First, construct the improvement layer 1, followed by the cushion layer 2; then construct the hydraulically hardening material treatment layer 3; after the strength reaches the design requirements, construct the stress diffusion intermediate layer 4; construct the prime coat 410 on the surface of the stress diffusion intermediate layer 4; after the prime coat 420 breaks, construct the seal coat 420, and then construct the subbase course 5; construct the emulsified asphalt lower bonding layer 510 on the subbase course 5, and then construct the base course 6 immediately; construct the emulsified asphalt upper bonding layer 610 and the surface course 7 on the base course 6. Each process needs to pass the quality acceptance before proceeding to the next process.

Claims

1. An inverted asphalt pavement structure, characterized in that: The invention comprises an improvement layer (1), a cushion layer (2), a hydraulic material treatment layer (3), a stress diffusion intermediate layer (4), a subbase layer (5), a base layer (6) and a surface layer (7) which are paved in sequence from bottom to top; the improvement layer (1) is 100 cm thick and is paved with sandy clay; the cushion layer (2) is 50 cm thick and is paved with sandy clay; the hydraulic material treatment layer (3) is 25 cm thick and is paved with 3% to 5% cement improved soil; the stress diffusion intermediate layer (4) is 12 cm thick and is paved with graded crushed stone with a particle size range of 0 to 20 mm; the subbase layer (5) is 9 to 10 cm thick and is paved with asphalt crushed stone; the base layer (6) is 9 cm thick and is paved with asphalt crushed stone; the surface layer (7) is 6 cm thick and is paved with semi-open graded asphalt concrete.

2. The inverted asphalt pavement structure according to claim 1, characterized in that: The paving materials used in the improved layer (1), cushion layer (2), hydraulic material treatment layer (3), stress diffusion intermediate layer (4), subbase layer (5), base layer (6) and surface layer (7) meet French requirements.

3. The inverted asphalt pavement structure according to claim 1, characterized in that: The base layer (5) and base layer (6) have better fatigue resistance than the surface layer (7) and have a load-bearing function; the material load-bearing capacity of the improved layer (1) and cushion layer (2) exceeds the domestic requirements for layers with the same function.

4. The inverted asphalt pavement structure according to claim 1, characterized in that: A permeable layer (410) and a sealing layer (420) are sequentially arranged between the stress diffusion intermediate layer (4) and the base layer (5); the permeable layer (410) is made of 0 / 1 grade diluted asphalt at a spraying dosage of 1 kg / m 2 The sealing layer is mainly used to seal the surface gaps of the stress diffusion intermediate layer (4) to prevent moisture from invading.

5. The inverted asphalt pavement structure according to claim 1, characterized in that: An emulsified asphalt lower bonding layer (510) is provided between the subbase layer (5) and the base layer (6); an emulsified asphalt upper bonding layer (610) is provided between the base layer (6) and the surface layer (7); the emulsified asphalt lower bonding layer (510) and the emulsified asphalt upper bonding layer (610) are made of cationic emulsified asphalt with a residual asphalt content of ≥65% and a spreading amount of ≥250 g / m 2 Paved.

6. The inverted asphalt pavement structure according to claim 1, characterized in that: The sandy clay used in the improved layer (1) has an organic matter content of <1.0%, a plasticity index of ≤25, a liquid limit of <50, and a California bearing ratio of ≥15; the sandy clay used in the cushion layer (2) has an organic matter content of <1.0%, a plasticity index of ≤25, a liquid limit of <50, a California bearing ratio of ≥20, and a secondary static deformation modulus EV2 of ≥80Mpa.

7. The inverted asphalt pavement structure according to claim 1, characterized in that: The cement-improved soil used in the hydraulic material treatment layer (3) is sandy clay or laterite granules; the organic matter content of the cement-improved soil used in the hydraulic material treatment layer (3) is ≤0.5%, the plasticity index is <20, and the 80μm sieve amount is ≤20%.

8. The inverted asphalt pavement structure according to claim 1, characterized in that: The compaction degree of the hydraulic material treatment layer (3) is ≥98%, and the 7d CBR value is ≥150.

9. The inverted asphalt pavement structure according to claim 1, characterized in that: The graded crushed stone used in the stress diffusion intermediate layer (4) has a 80 μm sieving rate of 4% to 9% and a methylene blue value of <0.1%.

10. The inverted asphalt pavement structure according to claim 1, characterized in that: The asphalt content of the asphalt crushed stone used in the subbase (5) and the base layer (6) is ≥4.2%, and the abundance coefficient K is ≥2.8; the asphalt content of the semi-open graded asphalt concrete used in the surface layer (7) is ≥5.0%, and the abundance coefficient K is ≥3.2.

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