Anti-crack pavement structure in high-altitude area and construction method of anti-crack pavement structure

Abstract

The invention relates to an anti-crack pavement structure in a high-altitude area and a construction method of the anti-crack pavement structure in the technical field of civil engineering. The pavement structure comprises an ultra-low-dose cement stabilized macadam upper base layer and an asphalt-rich stress absorbing layer. The upper base layer of the pavement structure adopts graded broken stone doped with ultralow-dose cement, the strength of the base layer is reduced, the base layer turns from semi-rigid to semi-flexible, after the base layer is matched with the surface layer modulus and deformation inconsistency is reduced, base layer cracks are reflected to the surface layer, meanwhile, it is guaranteed that the upper base layer is not loosened during construction, and residual deformation is reduced in the later period; the asphalt-rich stress absorption layer is constructed at the top of the pavement, so that the influence of base layer cracks reflected to an asphalt surface layer is reduced, the pavement cracks are reduced, the influence of moisture on a roadbed can be reduced, and the overall stability and performance durability of the pavement are improved; the base layer reflection cracks in northwest regions with large temperature difference, high altitude and strong ultraviolet radiation are reduced, the service life of the pavement is prolonged, the maintenance cost is reduced, and the application prospect is wide.

Description

Technical Field

[0001] This application relates to the field of civil engineering technology, and in particular to a crack-resistant pavement structure for high-altitude areas and its construction method. Background Technology

[0002] To improve the service life of pavement structures, my country has long adopted the design philosophy of "strong base, thin surface, and stable subgrade." Based on my country's economic foundation and the current state of highway construction, inorganic binder-stabilized base courses, represented by cement-stabilized crushed stone, will continue to be widely used in pavement structures of highways of all grades for a considerable period due to their advantages such as good load-bearing capacity, high stability, and strong frost resistance. However, inorganic binder-stabilized base course materials are brittle and highly sensitive to changes in humidity and temperature. During service, the combined effects of temperature, humidity, and load make them prone to cracking. These cracks then extend to the asphalt pavement shortly after the road is opened to traffic, forming reflective cracks that ultimately affect the surface course and service performance, resulting in significant social and economic losses.

[0003] Although some provinces in China have begun to use flexible base courses to reduce reflective cracking in the base course, the cost of the structures used, such as asphalt macadam and fiber-reinforced graded macadam, is relatively high. Inverted graded macadam structures are widely used in Fujian Province, but due to residual deformation and fatigue risks, as well as the influence of temperature and humidity environmental factors, they have not been promoted in China.

[0004] Therefore, this invention is proposed. Summary of the Invention

[0005] In view of the problems existing in the background technology, this application provides a crack-resistant pavement structure and its construction method for high-altitude areas. It can reduce the strength of the base course, making the base course change from semi-rigid to semi-flexible, thereby matching the modulus with the surface course. This reduces the possibility of base course cracks reflecting to the surface course after deformation inconsistency, reduces the residual deformation and fatigue risks of the graded crushed stone base course, and further alleviates the damage to the base course caused by upward reflection of cracks and sealing the surface course water seepage through the asphalt-rich stress absorption layer. It is particularly suitable for the impact of rain, snow and freeze-thaw on the pavement in high-altitude areas of Northwest China, and extends the service life of the pavement.

[0006] According to one aspect of the present invention, a crack-resistant pavement structure for high-altitude areas is provided, comprising, from bottom to top, a cement-stabilized crushed stone subbase, a cement-stabilized crushed stone lower base, an ultra-low dosage cement-stabilized crushed stone upper base, a lower layer, an intermediate layer, and a top layer; wherein the cement dosage of the ultra-low dosage cement-stabilized crushed stone upper base is lower than that of the cement-stabilized crushed stone subbase and the cement-stabilized crushed stone lower base, and no strength or core sampling tests are performed; an asphalt-rich stress-absorbing layer is laid between the ultra-low dosage cement-stabilized crushed stone upper base and the lower layer.

[0007] In some embodiments of the present invention, the cement dosage of the cement-stabilized crushed stone subbase is lower than the cement dosage of the cement-stabilized crushed stone underbase.

[0008] In some embodiments of the present invention, the cement dosage of the ultra-low dosage cement-stabilized crushed stone upper base course is 1.0% to 2.0% by weight, the cement dosage of the cement-stabilized crushed stone lower base course is 2.5% to 3.0%, and the cement dosage of the cement-stabilized crushed stone lower base course is 3.5% to 4.0%.

[0009] In some embodiments of the present invention, the thickness of the ultra-low dose cement-stabilized crushed stone upper base course, the cement-stabilized crushed stone lower base course, and the cement-stabilized crushed stone lower base course are each independently 18cm~20cm.

[0010] In some embodiments of the present invention, the thickness of the asphalt-rich stress-absorbing layer is 1.5cm to 2.5cm.

[0011] In some embodiments of the present invention, the lower layer is made of AC25 asphalt concrete or ATB25 asphalt concrete; the thickness of the lower layer is 7.5cm to 8.5cm.

[0012] In some embodiments of the present invention, the intermediate layer is made of AC20 concrete asphalt or Sup20 concrete asphalt; the thickness of the intermediate layer is 5.5cm to 6.5cm.

[0013] In some embodiments of the present invention, the top layer is made of AC13 asphalt concrete or SMA13 asphalt concrete; the thickness of the top layer is 3.5cm to 4.5cm.

[0014] According to another aspect of the present invention, a construction method for a crack-resistant pavement structure in high-altitude areas as described above is provided, comprising the following steps: spreading and compacting a 2.5%~3.0% cement-stabilized crushed stone mixture to obtain a cement-stabilized crushed stone subbase; spraying a measured amount of cement slurry on the cement-stabilized crushed stone subbase, then spreading and compacting a 3.5%~4.0% cement-stabilized crushed stone mixture to obtain a cement-stabilized crushed stone lower base; spraying a measured amount of cement slurry on the cement-stabilized crushed stone lower base, then spreading and compacting a 1.0%~2.0% ultra-low dosage cement-stabilized crushed stone mixture to obtain an ultra-low dosage cement-stabilized crushed stone upper base, and performing curing by covering with a cloth and a film and sprinkling water; spraying a tack coat on the ultra-low dosage cement-stabilized crushed stone upper base, and sequentially laying an asphalt-rich stress-absorbing layer, a lower layer, an intermediate layer, and a top layer to obtain the crack-resistant pavement structure in high-altitude areas.

[0015] Compared with the prior art, the present invention achieves the following technical effects: This invention proposes using ultra-low dosage cement-stabilized crushed stone mixture to form an ultra-low dosage cement-stabilized crushed stone upper base course. This reduces the base course strength, transforming it from semi-rigid to semi-flexible, matching the modulus with the surface course. This reduces the reflection of base course cracks to the surface course after deformation inconsistency, thus reducing residual deformation and fatigue risks in the graded crushed stone base course. At the same time, the application of a certain thickness of asphalt-rich stress-absorbing layer further mitigates the upward reflection of cracks and seals the damage to the base course caused by water seepage from the surface course. This invention is particularly suitable for the impact of rain, snow, and freeze-thaw cycles on road surfaces in high-altitude areas of Northwest China, effectively extending the service life of the road surface. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the crack-resistant pavement structure of the present invention; Figure 2 This is a schematic diagram of the crack-resistant pavement structure of Example 1.

[0017] The labels in the attached diagram represent the following: 1. Cement-stabilized crushed stone subbase; 2. Cement-stabilized crushed stone lower base; 3. Ultra-low dosage cement-stabilized crushed stone upper base; 4. Asphalt-rich stress-absorbing layer; 5. Lower layer; 6. Middle layer; 7. Upper layer. Detailed Implementation

[0018] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0019] In the following description, when referring to the accompanying drawings, the same numbers in different drawings denote the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0020] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0021] Inorganic binder-stabilized base course materials are brittle and highly sensitive to changes in humidity and temperature. During service, they are easily prone to cracking due to the combined effects of temperature, humidity, and load. Although some provinces in China have begun to use flexible base courses to reduce reflective cracking, such as Shandong Province laying a 10cm-15cm asphalt-aggregate structure on top of a water-stabilized base course as a flexible base course; Fujian Province using an inverted structure consisting of a water-stabilized subbase, a lower base course, and a 15cm graded aggregate structure as a stress-absorbing layer; and Hebei Province constructing a three-layer graded aggregate base course (with fiber admixture) as a test road, research showed that flexible base courses effectively reduced reflective cracking in cement-stabilized structures. However, asphalt-aggregate and fiber-admixed graded aggregate structures are relatively expensive, and inverted structure graded aggregate is difficult to compact, posing risks of residual deformation and fatigue. Therefore, they have not been widely adopted in China.

[0022] Therefore, this application proposes a crack-resistant pavement structure and its construction method for high-altitude areas, which can effectively solve the problem of pavement structural cracking and is particularly suitable for the impact of rain, snow and freeze-thaw cycles on pavement in high-altitude areas of Northwest China, effectively extending the service life of pavement.

[0023] This application discloses a crack-resistant pavement structure for high-altitude areas. For example... Figure 1 As shown, the crack-resistant pavement structure in high-altitude areas includes, from bottom to top, layers of cement-stabilized crushed stone subbase 1, cement-stabilized crushed stone lower base 2, ultra-low dosage cement-stabilized crushed stone upper base 3, lower layer 5, middle layer 6, and upper layer 7. Among them, the cement dosage of cement-stabilized crushed stone upper base 3 is lower than that of cement-stabilized crushed stone subbase 1 and cement-stabilized crushed stone lower base 2, respectively. An asphalt-rich stress-absorbing layer 4 is laid between ultra-low dosage cement-stabilized crushed stone upper base 3 and lower layer 5.

[0024] In this invention, the use of low-dose cement-stabilized crushed stone as the base course reduces the strength of the base course, transforming it from semi-rigid to semi-flexible, matching the modulus of the surface layer. This reduces the likelihood of base course cracks reflecting onto the surface layer after inconsistent deformation, and also reduces residual deformation and fatigue risks in the graded crushed stone base course. Simultaneously, the asphalt-rich stress-absorbing layer further mitigates upward reflection of cracks and seals the damage to the base course caused by surface layer water seepage, improving the overall stability and durability of the pavement. Under the premise that the pavement structural strength, base course fatigue cracking, surface layer permanent deformation, and surface layer fatigue cracking performance meet design requirements, this invention solves the problem of pavement structural cracking. It is particularly suitable for the impact of rain, snow, and freeze-thaw cycles on pavements in high-altitude areas of Northwest China, helping to reduce reflective cracking in the base course in Northwest China, which has large temperature differences, high altitude, and strong ultraviolet radiation, effectively extending the service life of the pavement. Moreover, the pavement structure is simple, rationally designed, easy to construct, and reduces maintenance costs, showing broad application prospects.

[0025] In some embodiments of the present invention, the cement dosage of the cement-stabilized crushed stone subbase is lower than that of the cement-stabilized crushed stone underbase.

[0026] In this embodiment, by using cement-stabilized crushed stone subbase and cement-stabilized crushed stone lower base with conventional cement dosage, and setting the cement dosage of the cement-stabilized crushed stone subbase to be lower than that of the cement-stabilized crushed stone lower base, the overall strength of the pavement structure layer can be effectively guaranteed.

[0027] In some embodiments of the present invention, the cement in the cement-stabilized crushed stone is added externally by weight percentage, the aggregate ratio is 100, and the cement dosage refers to the percentage of cement mass to aggregate mass, that is, the cement dosage is based on the total weight of the aggregate, and the cement dosage = (cement weight / total aggregate weight) × 100%. The cement dosage for the ultra-low dosage cement-stabilized crushed stone upper base course is 1.0%~2.0%, the cement dosage for the cement-stabilized crushed stone subbase course is 2.5%~3.0%, and the cement dosage for the cement-stabilized crushed stone lower base course is 3.5%~4.0%.

[0028] Preferably, the thickness of the ultra-low dosage cement-stabilized crushed stone upper base course, cement-stabilized crushed stone subbase course, and cement-stabilized crushed stone lower base course is 18cm~20cm, respectively.

[0029] In this embodiment, an ultra-low dosage cement-stabilized crushed stone upper base layer of 18cm~20cm is added with about 1.0%~2.0% cement. This structural layer serves as a reflective crack reduction layer. With the help of its stress dissipation effect, it can effectively solve the shortcomings of the graded crushed stone due to resonance looseness during the rolling process. After adding low dosage cement, it is beneficial to the molding of cement-stabilized graded crushed stone. The water-stabilized base layer is a semi-rigid and semi-flexible structure, which ensures that the modulus of the water-stabilized mixture is closer to or consistent with the modulus of the surface layer.

[0030] Preferably, the thickness of the asphalt-rich stress-absorbing layer is 1.5cm to 2.5cm. The asphalt-rich stress-absorbing layer is a mixture of asphalt and crushed stone, which is mixed at a mixing plant, laid by a paver, and compacted.

[0031] In this embodiment, the 1.5cm~2.5cm asphalt-rich stress-absorbing layer, by increasing the amount of asphalt and compared with the conventional process of separately spreading and compacting asphalt and crushed stone, has a porosity of about 2% in the mixture. Compared with the three layers of upper, middle and lower layers used in the conventional design of road surface structure in China, which often use AC dense gradation or SMA skeleton dense structure, the porosity of the pavement structure is as high as 4%. The asphalt-rich stress-absorbing layer of this invention can effectively reduce the impact of water on the pavement in areas with severe rain, snow and freeze-thaw cycles.

[0032] In some embodiments of the present invention, the lower layer may be AC25 asphalt concrete or ATB25 asphalt concrete; the thickness of the lower layer is 7.5cm to 8.5cm.

[0033] In some embodiments of the present invention, the intermediate layer may be made of AC20 concrete asphalt or Sup20 concrete asphalt; the thickness of the intermediate layer is 5.5cm to 6.5cm.

[0034] In some embodiments of the present invention, the top layer may be AC13 asphalt concrete or SMA13 asphalt concrete; the thickness of the top layer is 3.5cm to 4.5cm.

[0035] This embodiment also proposes a construction method for the above-mentioned crack-resistant pavement structure in high-altitude areas, which includes the following steps: Spread and compact a 2.5%~3.0% cement-stabilized crushed stone mixture to obtain a cement-stabilized crushed stone subbase.

[0036] On a cement-stabilized crushed stone subbase, a measured amount of cement slurry is sprinkled, and a 3.5%~4.0% cement-stabilized crushed stone mixture is spread and compacted to obtain the cement-stabilized crushed stone subbase.

[0037] On the cement-stabilized crushed stone lower base, a certain amount of cement slurry is sprinkled, and a mixture of 1.0%~2.0% ultra-low dosage cement-stabilized crushed stone is spread and compacted to obtain an ultra-low dosage cement-stabilized crushed stone upper base, which is then covered with a cloth and a film and sprayed with water for curing.

[0038] By spraying a tack coat onto an ultra-low dose cement-stabilized crushed stone base course and then sequentially laying an asphalt-rich stress-absorbing layer, a lower layer, a middle layer, and a top layer, a crack-resistant pavement structure for high-altitude areas is obtained.

[0039] The construction method of the high-altitude crack-resistant pavement structure described above in this application will be further explained below with reference to specific embodiments.

[0040] Example 1 1) such as Figure 2 As shown, an 18cm thick cement-stabilized crushed stone base course with standard dosage is laid, compacted, and then cement slurry is sprinkled to achieve a pure cement concentration of 0.6kg / m³. 2 ~1.0kg / m 2 This ensures the connection between the subsequent cement-stabilized crushed stone subbase and the cement-stabilized crushed stone base course.

[0041] 2) Lay an 18cm thick layer of standard-dosage cement-stabilized crushed stone subbase on the cement-stabilized crushed stone base course, compact it, and sprinkle cement slurry to achieve a pure cement concentration of 0.6kg / m³. 2 ~1.0kg / m 2 This ensures the connection between the ultra-low dosage cement-stabilized crushed stone upper base course and the cement-stabilized crushed stone lower base course.

[0042] 3) Lay an 18cm thick layer of low-dose and ultra-low-dose cement-stabilized crushed stone upper base on the cement-stabilized crushed stone lower base, compact it, and then perform curing with a cloth and a film.

[0043] 4) Spray tack coat on the ultra-low dosage cement-stabilized crushed stone base course and lay a 2cm thick asphalt-rich stress-absorbing layer.

[0044] 5) On the asphalt-rich stress-absorbing layer, lay an 8cm thick AC25 asphalt concrete lower layer, a 6cm thick AC20 concrete asphalt intermediate layer, and a 4cm thick AC13 asphalt concrete upper layer in sequence to finally obtain a crack-resistant pavement structure.

[0045] Test case The cumulative equivalent axle loads, low-temperature cracking index, asphalt layer penetration strength, and antifreeze thickness corresponding to asphalt layer rutting and semi-rigid layer fatigue cracking of the pavement structure and selected materials in Example 1 were verified respectively. Table 1. Experimental Results:

[0046] As shown in the table above, the selected pavement structure and materials meet the requirements of all calculations. The pavement structure of this invention is simple and does not require additional large equipment. By incorporating low-dose cement into graded crushed stone, it avoids the residual deformation and fatigue risks caused by current graded crushed stone and reduces the modulus of high-dose water-stabilized base course, maintaining consistency with the modulus of flexible pavement. By adding a 2cm thick asphalt-rich stress-absorbing layer, it prevents rainwater and snowmelt from seeping into the subgrade and causing overall damage to the pavement structure. Therefore, it significantly improves pavement durability and reduces pavement maintenance costs. Calculations show that all indicators of this crack-resistant pavement structure are superior to pavement design specifications. It is foreseeable that this pavement structure can guarantee the long-term performance of the pavement under long-term loads and has broad application prospects.

[0047] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A crack-resistant pavement structure for high-altitude areas, characterized in that, It includes a cement-stabilized crushed stone subbase, a cement-stabilized crushed stone lower base, an ultra-low dosage cement-stabilized crushed stone upper base, a lower layer, a middle layer, and a top layer, laid from bottom to top. The cement dosage of the ultra-low dosage cement-stabilized crushed stone upper base course is lower than that of the cement-stabilized crushed stone lower base course and the cement-stabilized crushed stone lower base course, respectively. An asphalt-rich stress-absorbing layer is laid between the ultra-low dosage cement-stabilized crushed stone upper base course and the lower base course.

2. The crack-resistant pavement structure for high-altitude areas according to claim 1, characterized in that, The cement dosage of the cement-stabilized crushed stone subbase is lower than that of the cement-stabilized crushed stone underbase.

3. The crack-resistant pavement structure for high-altitude areas according to claim 2, characterized in that, By weight percentage, the cement content of the ultra-low dosage cement-stabilized crushed stone upper base course is 1.0%~2.0%, the cement content of the cement-stabilized crushed stone lower base course is 2.5%~3.0%, and the cement content of the cement-stabilized crushed stone lower base course is 3.5%~4.0%.

4. The crack-resistant pavement structure for high-altitude areas according to claim 3, characterized in that, The thicknesses of the ultra-low dosage cement-stabilized crushed stone upper base course, cement-stabilized crushed stone subbase course, and cement-stabilized crushed stone lower base course are each 18cm to 20cm.

5. The crack-resistant pavement structure for high-altitude areas according to claim 1, characterized in that, The thickness of the asphalt-rich stress-absorbing layer is 1.5cm to 2.5cm.

6. The crack-resistant pavement structure for high-altitude areas according to claim 1, characterized in that, The lower layer is made of AC25 asphalt concrete or ATB25 asphalt concrete. The thickness of the lower layer is 7.5cm to 8.5cm.

7. The crack-resistant pavement structure for high-altitude areas according to claim 1, characterized in that, The intermediate layer is made of AC20 concrete asphalt or Sup20 concrete asphalt. The thickness of the intermediate layer is 5.5cm to 6.5cm.

8. The crack-resistant pavement structure for high-altitude areas according to claim 1, characterized in that, The upper layer is made of AC13 asphalt concrete or SMA13 asphalt concrete. The thickness of the top layer is 3.5cm to 4.5cm.

9. A construction method for a crack-resistant pavement structure in high-altitude areas as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Spread and compact a 2.5%~3.0% cement-stabilized crushed stone mixture to obtain a cement-stabilized crushed stone subbase. On the cement-stabilized crushed stone subbase, a measured amount of cement slurry is sprinkled, and a 3.5%~4.0% cement-stabilized crushed stone mixture is spread and compacted to obtain the cement-stabilized crushed stone lower base. On the cement-stabilized crushed stone lower base, a certain amount of cement slurry is sprinkled, and a 1.0%~2.0% ultra-low dosage cement-stabilized crushed stone mixture is spread and compacted to obtain an ultra-low dosage cement-stabilized crushed stone upper base, and then cured with a cloth and a film. A tack coat is applied to the ultra-low dosage cement-stabilized crushed stone base course, and then an asphalt-rich stress-absorbing layer, a lower layer, a middle layer, and a top layer are laid in sequence to obtain the crack-resistant pavement structure for high-altitude areas.

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