Low-carbon anti-crack pavement base structure

Abstract

The utility model discloses a low-carbon anti-crack pavement base structure. The low-carbon anti-cracking pavement base structure comprises a modified asphalt mixture upper surface layer, a modified asphalt concrete middle surface layer, an asphalt concrete lower surface layer, an asphalt stabilized macadam flexible upper base layer, a lower sealing layer, a super sulfate cement fiber stabilized macadam lower base layer, a super sulfate cement stabilized macadam subbase layer and subgrade soil from top to bottom, the pavement base structure disclosed by the utility model can meet the structural bearing capacity and fully utilize the recycled aggregate, has the advantages of low carbon, crack resistance and high toughness, reduces the generation of dry shrinkage and temperature shrinkage cracks, enhances the durability of a road base and prolongs the service life of a road.

Description

Technical Field

[0001] This utility model relates to a road base structure, and more particularly to a low-carbon, crack-resistant road base structure. Background Technology

[0002] Semi-rigid base asphalt pavement is the most common pavement structure used on highways in my country. However, due to the inherent thermal shrinkage cracking and drying shrinkage cracking problems of the cement-stabilized crushed stone materials commonly used in semi-rigid bases, these cracks easily propagate and reflect onto the asphalt surface layer under load, forming reflective cracks. Surface moisture can easily penetrate into the pavement structure through these cracks, leading to pumping, base layer delamination, and large-scale cracking and pothole damage in the surface layer, reducing the pavement structure's load-bearing capacity, affecting driving safety and comfort, and shortening the service life of the pavement structure. Therefore, the cracking problem of semi-rigid bases has become a technical challenge affecting the normal use of highways. Furthermore, cement-stabilized base materials require a large amount of cement, and the cement production process involves significant carbon dioxide emissions. Meanwhile, the loss and recycling rate of construction materials during road maintenance are low. How to effectively reduce carbon emissions while ensuring road performance has become an important research topic in the field of road engineering.

[0003] To address the frequent reflective cracking problem in semi-rigid base asphalt pavements, existing technologies employ various composite pavement structures to suppress reflective cracking. For example, the patent application CN218756827U, entitled "A Composite Base Durable Pavement Structure for Suppressing Reflective Cracks," discloses a durable pavement structure consisting of a rutting-resistant asphalt surface layer, a graded crushed stone upper base layer, and a persulfate cement-stabilized crushed stone lower base layer. However, this structure utilizes a graded crushed stone upper base layer with very weak structural bearing capacity, and uses persulfate cement-stabilized crushed stone as the lower base layer. This further reduces the overall load-bearing capacity of the structure, making it unable to withstand high vehicle loads and limiting its applicability in high-grade highways. The patent application CN222119812U, entitled "A Pavement Base Structure," uses micro-expansion cement as the upper base layer binder and pre-cut joints in the water-stabilized lower base layer to reduce expansion and contraction along the driving direction. The anti-cracking measures adopted in the above structure only play a role in reducing drying shrinkage and thermal shrinkage in the early stage of pavement structure service. They ignore the adverse effects of repeated vehicle loads on the structure during the long service life of the road and cannot reduce or suppress the occurrence of reflective cracks throughout the entire life cycle.

[0004] Therefore, it is necessary to provide a low-carbon, crack-resistant, and durable base pavement structure that not only meets the load-bearing capacity requirements of high-grade highways and resists the generation and propagation of cracks throughout the entire service life of the pavement, but also helps to reduce carbon emissions from road engineering. Summary of the Invention

[0005] Purpose of the invention: The purpose of this utility model is to provide a low-carbon, crack-resistant pavement base structure with strong crack resistance and structural bearing capacity.

[0006] Technical solution: This utility model discloses a low-carbon crack-resistant pavement base structure, which includes the following structure from top to bottom: modified asphalt mixture surface layer, asphalt concrete bottom layer, lower sealing layer, supersulfate cement fiber stabilized crushed stone subbase, supersulfate cement stabilized crushed stone base course, and subgrade soil.

[0007] In a further preferred embodiment, a modified asphalt concrete intermediate layer is provided between the modified asphalt mixture upper layer and the asphalt concrete lower layer, and an asphalt-stabilized crushed stone flexible upper base layer is provided between the asphalt concrete lower layer and the lower sealing layer.

[0008] The modified asphalt mixture surface layer has a thickness of 4-6 cm, preferably 4 cm; the asphalt stabilized crushed stone flexible base course can effectively resist reflective cracks, increase the propagation distance of reflective cracks in the asphalt layer, prolong the propagation time, and improve the fatigue life of the pavement structure.

[0009] The thickness of the surface layer in the modified asphalt concrete is 6-8 cm.

[0010] The thickness of the asphalt concrete lower layer is 8-10 cm.

[0011] The thickness of the asphalt-stabilized crushed stone flexible upper base course is 8-12cm, preferably 10cm.

[0012] The lower seal layer is an asphalt-aggregate mixture with a thickness of 1.5–2 cm; the asphalt is petroleum asphalt or emulsified asphalt, the aggregate size is 5–10 mm, and the amount used is controlled at 5–8 m³. 3 / 1000m 2 .

[0013] The thickness of the supersulfate cement fiber-stabilized crushed stone subbase is 18cm to 36cm, the length of the polypropylene fibers incorporated is 15 to 20mm, and the dosage ranges from 0.9kg / m². 3 ~2.0kg / m 3 The thickness of the supersulfate cement stabilized crushed stone subbase is 18cm to 20cm.

[0014] Invention Principle: This invention relates to a low-carbon, crack-resistant pavement base structure. It utilizes a multi-layered design to create a pavement structure with strong crack resistance and load-bearing capacity. The flexible asphalt-stabilized crushed stone upper base effectively resists reflective cracking, increases the propagation distance of reflective cracks within the asphalt layer, prolongs the propagation time, and improves the fatigue life of the pavement structure. The lower sealing layer, acting as a transition layer, provides bonding and strengthens interlayer connections. The thicker supersulfate cement fiber-stabilized crushed stone lower base can bear the traffic loads transferred from the surface layer. Simultaneously, the presence of fibers enhances the compressive and flexural tensile strength of the lower base. The supersulfate cement subbase and lower base work together in the early stages of pavement construction to effectively reduce thermal shrinkage cracks caused by temperature stress and drying shrinkage cracks caused by decreased moisture content.

[0015] This utility model's low-carbon, crack-resistant pavement base structure can be tailored to different road grades. For low-grade highways, considering economic and cost factors, the surface layer consists of a modified asphalt mixture surface layer and an asphalt concrete base layer, with a lower sealing layer to enhance the connection between the surface layer and the base layer. The lower base layer is equipped with a supersulfate cement fiber-stabilized crushed stone layer. The combined crack-resistant properties of supersulfate cement and fiber allow the pavement base structure to effectively resist the adverse effects of cracking throughout its service life. The lower base layer, in conjunction with the supersulfate cement subbase, prevents bottom-up cracking caused by tension at the bottom of the base layer. For high-grade highways, a modified asphalt concrete intermediate surface layer and an asphalt-stabilized crushed stone flexible upper base layer are further added. This increases the surface layer combination and improves the load-bearing capacity of the pavement structure to cope with the extremely heavy traffic loads of high-grade highways. The asphalt-stabilized crushed stone flexible upper base layer further increases the propagation distance of reflective cracks in the asphalt layer, thereby extending the propagation time and improving the fatigue life of the pavement structure.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The low-carbon crack-resistant pavement base structure of the present invention has extremely strong crack resistance and structural bearing capacity, meets the bearing capacity requirements of highways of various grades, resists the generation and propagation of cracks, extends the service life of the pavement, and helps to reduce the carbon emissions of road engineering. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the road base structure of Embodiment 1 of this utility model;

[0018] Figure 2 This is a schematic diagram of the road base structure of Embodiment 2 of this utility model;

[0019] Among them: 1- Modified asphalt mixture surface layer, 2- Modified asphalt concrete intermediate layer, 3- Asphalt concrete lower layer, 4- Asphalt stabilized crushed stone flexible upper base course, 5- Lower seal layer, 6- Supersulfate cement fiber stabilized crushed stone lower base course, 7- Supersulfate cement stabilized crushed stone subbase course, 8- Subgrade soil. Detailed Implementation

[0020] The technical solution of this utility model will be further described below with reference to the embodiments. The test materials used in the embodiments can all be purchased through conventional means.

[0021] Example 1

[0022] The low-carbon, crack-resistant pavement base structure of this utility model includes the following structure from top to bottom: modified asphalt mixture upper layer 1, asphalt concrete lower layer 3, lower sealing layer 5, supersulfate cement fiber stabilized crushed stone lower base layer 6, supersulfate cement stabilized crushed stone subbase layer 7, and subgrade soil 8.

[0023] Among them, the modified asphalt mixture upper layer 1 has a thickness of 4cm, the asphalt concrete lower layer 3 has a thickness of 8cm, the lower seal layer 5 has a thickness of 2cm, the supersulfate cement fiber stabilized crushed stone lower base layer 6 has a thickness of 36cm, and the supersulfate cement stabilized crushed stone subbase layer 7 has a thickness of 20cm.

[0024] Example 2

[0025] The low-carbon, crack-resistant pavement base structure of this utility model includes the following structures from top to bottom: modified asphalt mixture surface layer 1, modified asphalt concrete intermediate layer 2, asphalt concrete bottom layer 3, asphalt stabilized crushed stone flexible upper base layer 4, lower sealing layer 5, supersulfate cement fiber stabilized crushed stone lower base layer 6, supersulfate cement stabilized crushed stone subbase layer 7, and subgrade soil 8.

[0026] Among them, the modified asphalt mixture surface layer 1 has a thickness of 4cm, the modified asphalt concrete intermediate layer 2 has a thickness of 6cm, the asphalt concrete bottom layer 3 has a thickness of 8cm, the asphalt stabilized crushed stone flexible upper base layer 4 has a thickness of 10cm, the lower sealing layer 5 has a thickness of 2cm, the supersulfate cement fiber stabilized crushed stone lower base layer 6 has a thickness of 36cm, and the supersulfate cement stabilized crushed stone subbase layer 7 has a thickness of 20cm.

[0027] The flexible upper base course of asphalt-stabilized crushed stone can effectively resist reflective cracking, increase the propagation distance of reflective cracks in the asphalt layer, prolong the propagation time, and improve the fatigue life of the pavement structure.

[0028] The supersulfate cement fiber stabilized crushed stone subbase 6 and supersulfate cement stabilized crushed stone base course 7 use supersulfate cement whose raw materials are more than 95% solid waste such as slag and gypsum, and only less than 5% cement clinker, which reduces the carbon emission per unit mass of cementitious materials in the base course by more than 50%. Supersulfate cement fiber stabilized crushed stone subbase 6 and supersulfate cement stabilized crushed stone base course 7 are composed of aggregate and binder, and the binder ratio is slag: desulfurized gypsum: silicate cement = 16:3:1.

[0029] The fiber-stabilized crushed stone subbase 6 uses fiber cement stabilized crushed stone composed of cement binder, crushed stone aggregate, and polypropylene fiber. On the one hand, it compensates for the loss of overall structural bearing capacity caused by the reduction of cement content in the subbase and base course. On the other hand, the use of fiber can reduce the original thermal shrinkage and drying shrinkage cracks in the matrix of the subbase. During the load-bearing stage, it can also effectively delay crack propagation, improve the crack resistance and toughness of cement stabilized crushed stone, and enable the matrix to continue to maintain its ability to resist deformation and cracking after cracking.

[0030] After the supersulfate cement stabilized crushed stone base course 7 is laid and cured, the main hydration product of supersulfate cement, ettringite, is generated by the reaction of the solid and liquid phases. The resulting expansion force puts pressure on the base course, thereby offsetting or reducing thermal shrinkage cracks caused by temperature stress and drying shrinkage cracks caused by the decrease in water content.

[0031] Therefore, the road base structure of this utility model can meet the structural bearing capacity and make full use of recycled aggregates, while having the advantages of low carbon, crack resistance and high toughness, reducing the generation of drying shrinkage and thermal shrinkage cracks, enhancing the durability of the road base, and extending the service life of the road.

Claims

1. A low carbon anti-cracking pavement base structure, characterized by, The low-carbon anti-cracking pavement base structure comprises, from top to bottom, a modified asphalt mixture upper layer (1), an asphalt concrete lower layer (3), a lower seal coat (5), an ultra-sulfate cement fiber stabilized macadam lower base layer (6), an ultra-sulfate cement stabilized macadam bottom base layer (7), and a roadbed soil (8).

2. The low carbon anti-cracking pavement base structure according to claim 1, characterized by, The modified asphalt mixture upper layer (1) and the asphalt concrete lower layer (3) are provided with a modified asphalt concrete middle layer (2) therebetween, and the asphalt concrete lower layer (3) and the lower seal coat (5) are provided with an asphalt stabilized macadam flexible upper base layer (4) therebetween.

3. The low carbon anti-cracking pavement base structure according to claim 1, characterized by, The modified asphalt mixture upper layer (1) has a thickness of 4-6 cm.

4. The low carbon anti-cracking pavement base structure according to claim 2, wherein, The modified asphalt concrete middle layer (2) has a thickness of 6-8 cm.

5. The low carbon anti-cracking pavement base structure according to claim 1, wherein, The asphalt concrete lower layer (3) has a thickness of 8-10 cm.

6. The low carbon anti-cracking pavement base structure according to claim 2, wherein, The asphalt stabilized macadam flexible upper base layer (4) has a thickness of 8-12 cm.

7. The low carbon anti-cracking pavement base structure according to claim 1, wherein, The lower seal coat (5) is an asphalt macadam mixture lower seal coat, and has a thickness of 1.5-2 cm.

8. The low carbon anti-cracking pavement base structure according to claim 1, wherein, The ultra-sulfate cement fiber stabilized macadam lower base layer (6) has a thickness of 18-36 cm.

9. The low carbon anti-cracking pavement base structure according to claim 1, wherein, The ultra-sulfate cement stabilized macadam bottom base layer (7) has a thickness of 18-20 cm.

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