A method of repairing an asphalt pavement with a trench

Abstract

This invention discloses a method for repairing asphalt pavement through pipeline excavation, comprising the following steps: S1: Milling and crushing the original road structure in layers to produce old asphalt pavement waste and old base course waste; S2: Excavating a trench downwards from the top surface of the original roadbed, laying a pipeline, and filling the trench to the top surface of the original roadbed; S3: Processing the old base course waste to form recycled aggregate, and then mixing it to form self-compacting concrete; S4: Forming a self-compacting recycled concrete base course above the backfill material; S5: Crushing and screening the old asphalt pavement waste into a first waste with a small particle size and a second waste with a large particle size; S6: Heating the first waste, adding the first aggregate, adding asphalt and a recycling agent, and mixing to form a medium-grained recycled asphalt mixture, forming a recycled medium-grained asphalt concrete surface layer; S7: Heating the second waste, adding the second aggregate, adding asphalt and a recycling agent, and mixing to form a fine-grained recycled asphalt mixture, forming a recycled fine-grained asphalt concrete surface layer, thus completing the pavement repair.

Description

Technical Field

[0001] This invention relates to the field of road repair technology, and in particular to a method for repairing asphalt pavement through pipeline excavation. Background Technology

[0002] Currently, urban black and odorous water bodies and waterlogging seriously damage the living environment and the city's image. The root cause is primarily the severe constraint of combined sewer systems on urban drainage and flood control capabilities, and the inadequacy of urban drainage networks. Implementing rainwater and sewage separation projects is a crucial means of improving urban drainage systems, but many problems still exist in current urban rainwater and sewage separation projects. Currently, urban roads are mainly asphalt pavements. When laying pipelines, it is necessary to break down the original road structure, which generates a large amount of waste asphalt pavement materials and inorganic binders. If these materials are discarded, they will occupy land and pollute the environment. After the road is laid, it needs to be restored in time. However, the boundary of the pipeline trench operation surface makes it difficult to compact the road repair material. After the road is opened to traffic, the repaired road surface is prone to sinking. When inorganic binder stabilized material or plain concrete is used as the base layer to repair the road surface, it generally requires a closed curing period of up to 7 days, which prolongs the time of urban traffic congestion. After the road surface is repaired and opened to traffic, the large difference in modulus of the base material and the lack of coordination of the repair boundary make the joint between the repaired road surface and the existing road surface easy to be damaged under the action of external vehicle loads, which seriously affects the service life of the road surface and driving comfort. Summary of the Invention

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a method for repairing asphalt pavement through pipeline excavation, which saves materials and has a short maintenance time.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A method for repairing asphalt pavement after pipeline excavation includes the following steps:

[0006] S1: Based on the location of the pipeline design, the original road structure is milled and crushed in layers. The crushed original road surface layer produces old asphalt pavement waste material, and the crushed original road base layer produces old base layer waste material.

[0007] S2: Excavate a trench downward from the top surface of the original roadbed for laying the pipeline, lay the pipeline, and fill the trench to the top surface of the original roadbed with backfill material, the backfill material being located on the outer periphery of the pipeline;

[0008] S3: The old base waste material generated in step S1 is washed with water, crushed by a crusher, screened, and mixed into recycled aggregate. Then, water, sand, cement, and water-reducing agent are added and mixed at room temperature to prepare self-compacting concrete.

[0009] S4: By pouring the self-compacting concrete, a self-compacting recycled concrete base layer is formed above the backfill material;

[0010] S5: The old asphalt pavement waste material generated in step S1 is crushed and screened into first waste material with small particle size and second waste material with large particle size.

[0011] S6: Heat the first waste material, add the first aggregate, add asphalt and recycling agent and mix to form a medium-grained recycled asphalt mixture. Lay the medium-grained recycled asphalt mixture on top of the self-compacting recycled concrete base layer to form a recycled medium-grained asphalt concrete surface layer.

[0012] S7: Heat the second waste material, add the second aggregate, add asphalt and recycling agent and mix to form a fine-grained recycled asphalt mixture. Lay the fine-grained recycled asphalt mixture on top of the recycled medium-grained asphalt concrete surface layer to form a recycled fine-grained asphalt concrete surface layer, thus completing the road repair.

[0013] Preferably, in step S2, a crushed stone cushion layer is laid on top of the backfill material, the crushed stone cushion layer is located at the top of the trench, the self-compacting recycled concrete base layer is located on top of the crushed stone cushion layer, the thickness of the crushed stone cushion layer is 15-20cm, the backfill material includes crushed stone chips or medium-coarse sand, and the compaction degree of the backfill material after filling is not less than 95%.

[0014] Preferably, in step S3, the particle size of the recycled aggregate is 5-31.5 mm, the cement is P.O42.5 grade fast-setting, fast-hardening, and early-strength cement, the water-reducing agent is polycarboxylate water-reducing agent, and the mass ratio of cement, sand, the recycled aggregate, water, and polycarboxylate water-reducing agent is 1:2:3:0.6:0.06.

[0015] Preferably, in step S4, the thickness of the self-compacting recycled concrete base course is 25-35 cm. After the self-compacting recycled concrete base course has been cured for 5 hours, a tack coat, a slurry seal coat, and a fiberglass grid are sprayed sequentially from bottom to top on the top of the self-compacting recycled concrete base course. The fiberglass grid is then connected to the original road base course using a fixing device. The tack coat includes PC-2 type cationic emulsified asphalt, and the dosage of PC-2 type cationic emulsified asphalt is 0.7-1.5 L / m. 2 The slurry seal layer comprises ES-2 type emulsified asphalt, with an ES-2 type emulsified asphalt dosage of 0.9–1.0 L / m³. 2 The fiberglass grid has a longitudinal and transverse strength of 50-80 KN / m and an elongation at break of no more than 3%.

[0016] Preferably, the fixing device includes U-shaped nails, the fiberglass grid is located above the self-compacting recycled concrete base layer, the outer periphery of the fiberglass grid extends above the original road base layer, the U-shaped nails connect the outer periphery of the fiberglass grid to the original road base layer, the lateral spacing between adjacent U-shaped nails is 20m, and the longitudinal spacing is 100cm.

[0017] Preferably, in step S5, the heating temperature of the first waste material is 150°C, and before asphalt mixing, a recycling agent is sprayed on the surface of the first waste material, with the amount of recycling agent being 4 to 7% of the weight of the first waste material.

[0018] Preferably, in step S6, the recycled medium-grained asphalt concrete surface layer is located on top of the fiberglass grid, the thickness of the recycled medium-grained asphalt concrete surface layer is 6 cm, the particle size of the first aggregate is 0-19.5 mm, the heating temperature of the first aggregate is 180 °C, and the heating temperature of the asphalt is 150 °C.

[0019] Preferably, in step S6, a tack coat is sprayed onto the top of the recycled medium-grained asphalt concrete surface layer. The tack coat is PC-3 type emulsified asphalt, and the dosage of the tack coat is 0.3–0.6 L / m. 2 .

[0020] Preferably, in step S7, the heating temperature of the second waste material is 150°C. Before asphalt mixing, a recycling agent is sprayed onto the surface of the second waste material. The amount of the recycling agent is 4-7% of the weight of the second waste material. The fine-grained recycled asphalt mixture is laid on top of the tack coat and the recycled fine-grained asphalt concrete surface layer is compacted. The thickness of the recycled fine-grained asphalt concrete surface layer is 4cm. The particle size of the second aggregate is 0-13.2mm. The heating temperature of the second aggregate is 180°C, and the heating temperature of the asphalt is 150°C.

[0021] Preferably, the pipeline excavation asphalt pavement repair method further includes step S10: smoothing and shaping the recycled fine-grained asphalt concrete surface layer.

[0022] One of the above technical solutions has at least one of the following advantages or beneficial effects: This pipeline excavation asphalt pavement repair method recycles and utilizes the waste materials from the old base course and old asphalt pavement generated during the excavation and trenching of the original pavement surface and base course for pipeline laying. These recycled materials are then used to pave the excavated and demolished parts of the original road structure, achieving the recycling of waste materials. This effectively solves the problems of land occupation and environmental pollution caused by waste materials. The use of recycled old base course materials and the self-compacting recycled concrete base course with high fluidity, rapid early strength development, and vibration-free self-compacting properties effectively solves the problems of poor compaction due to limited boundary conditions at the construction site and long base course curing time. This significantly reduces the manpower required for the pouring and vibration processes at the construction site, enabling rapid pavement repair after pipeline laying, short base course curing time, reduced use of asphalt and aggregate, avoids land occupation and environmental pollution caused by excavated materials, timely opening of traffic, reducing urban congestion, and ensuring pavement service life and driving comfort.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram of an embodiment of the present invention. Detailed Implementation

[0026] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0027] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the purpose of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0028] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0029] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0030] in, Figure 1 The reference direction coordinate system of this invention is given below, in conjunction with... Figure 1 The directions shown illustrate embodiments of the present invention.

[0031] An embodiment of the present invention provides a method for repairing asphalt pavement through pipeline excavation, comprising the following steps:

[0032] S1: Based on the designed location of the pipeline 100, the original road structure 200 is milled and crushed in layers. The crushed original road surface layer 210 produces old asphalt pavement waste material, and the crushed original road base layer 220 produces old base layer waste material. It can be understood that the original road structure 200 includes the original road surface layer 210, the original road base layer 220 and the original roadbed 230 from top to bottom. The original road surface includes the original road surface layer 210 and the original road base layer 220.

[0033] S2: Excavate a trench 300 for laying the pipeline 100 from the top surface of the original roadbed 230 downwards, lay the pipeline 100, and fill the trench 300 to the top surface of the original roadbed 230 with backfill material 310. The backfill material 310 is located on the outer periphery of the pipeline 100. In other words, backfill material 310 is filled around the pipeline 100.

[0034] S3: The old base waste material generated in step S1 is washed with water, crushed by a crusher, screened, and mixed into recycled aggregate. Then, water, sand, cement, and water-reducing agent are added and mixed at room temperature to prepare self-compacting concrete.

[0035] S4: By pouring self-compacting concrete, a self-compacting recycled concrete base layer 400 is formed above the backfill material 310;

[0036] S5: The old asphalt pavement waste material generated in step S1 is crushed and screened into first waste material with small particle size and second waste material with large particle size. Specifically, the first waste material has a particle size greater than or equal to 5mm and the second waste material has a particle size less than 5mm.

[0037] S6: Heat the first waste material, add the first aggregate, add asphalt and recycling agent and mix to form a medium-grained recycled asphalt mixture. Lay the medium-grained recycled asphalt mixture on top of the self-compacting recycled concrete base course 400 to form a recycled medium-grained asphalt concrete surface course 500.

[0038] S7: Heat the second waste material, add the second aggregate, add asphalt and recycling agent and mix to form a fine-grained recycled asphalt mixture. Lay the fine-grained recycled asphalt mixture on top of the recycled medium-grained asphalt concrete surface layer 500 to form the recycled fine-grained asphalt concrete surface layer 600, thus completing the road repair.

[0039] This pipeline excavation and asphalt pavement repair method recycles and reuses the waste materials from the original pavement surface layer 210 and original pavement base layer 220 generated during pipeline excavation and trench laying. These recycled materials are then used to pave the excavated and demolished sections of the original pavement structure, achieving waste material recycling and effectively solving the problems of land occupation and environmental pollution caused by waste materials. The recycled base layer waste, combined with self-compacting recycled concrete base layer 400, features a low water-cement ratio, high fluidity, rapid early strength development, and self-compacting properties without vibration. Vibration can fill the formwork by its own weight, greatly reducing the manpower required for the pouring and vibration processes on the construction site. It effectively solves the problems of poor compaction due to limited boundary conditions and long base curing time on the construction site. It also enables rapid road repair after 100% pipeline laying, short base curing time, reduced use of asphalt and stone, avoids land occupation and environmental pollution from excavated materials, timely opening of traffic, reduced urban congestion, and ensures road service life and driving comfort.

[0040] See Figure 1 In step S2, a crushed stone cushion layer 320 is laid on top of the backfill material 310. The crushed stone cushion layer 320 is located on top of the trench 300. The self-compacting recycled concrete base layer 400 is located on top of the crushed stone cushion layer 320. The thickness of the crushed stone cushion layer 320 is 15-20cm. The backfill material 310 includes crushed stone chips or medium-coarse sand. The compaction degree of the backfill material 310 after filling is not less than 95%. The crushed stone cushion layer 320 is a graded crushed stone layer. In other words, the crushed stone cushion layer 320 is located between the backfill material 310 and the self-compacting recycled concrete base layer 400.

[0041] As a preferred embodiment of the present invention, see Figure 1 In step S3, the particle size of the recycled aggregate is 5-31.5 mm, the cement is P.O42.5 grade fast-setting and fast-hardening early-strength cement, and the water-reducing agent is polycarboxylate water-reducing agent. Preferably, the mass ratio of cement, sand, recycled aggregate, water and polycarboxylate water-reducing agent is 1:2:3:0.6:0.06.

[0042] See Figure 1 In some embodiments, in step S4, the thickness of the self-compacting recycled concrete base course 400 is 25-35 cm. After the self-compacting recycled concrete base course 400 has cured for 5 hours, a tack coat 410, a slurry seal coat 420, and a fiberglass geogrid 430 are sprayed sequentially from bottom to top on the top of the self-compacting recycled concrete base course 400. In other words, the tack coat 410 is spread on the top of the self-compacting recycled concrete base course 400, the slurry seal coat 420 is sprayed on top of the tack coat 410, and the fiberglass geogrid 430 is laid on top of the slurry seal coat 420. The fiberglass geogrid 430 is connected to the original road base course 220 using a fixing device. The tack coat 410 includes PC-2 type cationic emulsified asphalt, and the amount of PC-2 type cationic emulsified asphalt is 0.7-1.5 L / m. 2 The slurry seal 420 comprises ES-2 type emulsified bitumen, with a thickness of 6–10 mm and an ES-2 type emulsified bitumen dosage of 0.9–1.0 L / m³. 2 The fiberglass geogrid 430 has a longitudinal and transverse strength of 50-80 KN / m and a breaking elongation of no more than 3%. Preferably, the fiberglass geogrid 430 is BJG50*50, and the longitudinal and transverse overlap length between the webs of the fiberglass geogrid 430 is greater than 20cm. The fiberglass geogrid 430 is laid at the overlap between the repaired road surface and the original road base 220, which solves the problems of large difference in modulus of base material and inconsistency of repair boundary, and ensures the service life of the road surface and driving comfort.

[0043] In some embodiments, see Figure 1 The fixing device includes U-shaped nails 440. Fiberglass grid 430 is located above the self-compacting recycled concrete base layer 400. The outer periphery of the fiberglass grid 430 extends above the original road base layer 220. The U-shaped nails 440 connect the outer periphery of the fiberglass grid 430 to the original road base layer 220. The width of the fiberglass grid 430 is greater than the width of the self-compacting recycled concrete base layer 400. The width of the fiberglass grid 430 is 200mm larger on each side than the width of the self-compacting recycled concrete base layer 400. The lateral spacing between adjacent U-shaped nails 440 is 20mm, and the longitudinal spacing is 100cm.

[0044] Preferably, in step S5, the heating temperature of the first waste material is 150°C, and before asphalt mixing, a recycling agent is sprayed on the surface of the first waste material, with the amount of recycling agent being 4 to 7% of the weight of the first waste material.

[0045] See Figure 1 In step S6, the recycled medium-grained asphalt concrete surface layer 500 is located on top of the fiberglass grid 430. The thickness of the recycled medium-grained asphalt concrete surface layer 500 is 6cm. The particle size of the first aggregate is 0-19.5mm. The heating temperature of the first aggregate is 180℃. The grade of the asphalt is 70. The heating temperature is 150℃. Preferably, the weight ratio of the first waste material, the first aggregate, and the asphalt is 25:15:1.

[0046] In some embodiments, in step S6, tack coat 510 is sprayed onto the top of the recycled medium-grained asphalt concrete surface layer 500. The tack coat 510 is PC-3 type emulsified asphalt, and the dosage of the tack coat 510 is 0.3 to 0.6 L / m. 2 Specifically, the dosage of tack coat 510 is 0.5 L / m. 2 .

[0047] In a preferred embodiment of the present invention, in step S7, the heating temperature of the second waste material is 150°C. Before asphalt mixing, a recycling agent is sprayed onto the surface of the second waste material, and the amount of recycling agent is 4-7% of the weight of the second waste material. The fine-grained recycled asphalt mixture is laid on top of the tack coat 510 and compacted into a recycled fine-grained asphalt concrete surface layer 600. The thickness of the recycled fine-grained asphalt concrete surface layer 600 is 4cm. The particle size of the second aggregate is 0-13.2mm. The heating temperature of the second aggregate is 180°C, and the heating temperature of the asphalt is 150°C. Preferably, the weight ratio of the second waste material, the second aggregate, and the asphalt is 20:15:1.

[0048] Preferably, the pipeline excavation asphalt pavement repair method further includes S10: smoothing and shaping the recycled fine-grained asphalt concrete surface layer, opening it to traffic, thus completing the rapid repair of the pipeline excavation asphalt pavement.

[0049] Comparative Example 1:

[0050] In contrast, in step S1, the original road surface (including the original road surface layer 210 and the original road base layer 220) is milled and crushed in layers, and the old road surface material generated from the crushing is transported to the construction waste disposal site. In step S4, the self-compacting recycled concrete base layer 400 is replaced with plain concrete C20 base layer. In other words, in steps S6 and S7, the first waste material and the second waste material are not used. Instead, a fresh asphalt mixture is formed by mixing new asphalt and new aggregates. The other steps are the same as those of the present invention, resulting in Comparative Example 1.

[0051] Comparative Example 2:

[0052] In step S1, the original road surface (including the original road surface layer 210 and the original road base layer 220) is milled and crushed in layers, and the old road surface material generated from the crushing is transported to the construction waste disposal site. In step S4, the self-compacting recycled concrete base layer 400 is replaced with cement-stabilized crushed stone base layer, wherein the cement content is 5%. In steps S6 and S7, the first waste material and the second waste material are not used. In other words, in steps S6 and S7, the first waste material and the second waste material are not used. Instead, the asphalt mixture formed by mixing new asphalt and new aggregates is used. The other steps are the same as those of the present invention, resulting in Comparative Example 2.

[0053] Specific comparison method: High-temperature rutting tests, low-temperature bending tests, and water damage resistance tests were conducted on the asphalt mixtures used for pavement repair in Comparative Example 1 and Comparative Example 2 to evaluate the pavement repair materials' road performance. The test results are as follows:

[0054]

[0055] The experiments conducted show that the recycled asphalt mixture prepared from waste asphalt pavement in this scheme contains aged asphalt, has fewer lightweight components, higher hardness, and higher viscosity. At the same time, the aged asphalt has lower water temperature sensitivity and can effectively resist the spalling effect between asphalt and aggregate. As a result, the recycled asphalt mixture in this scheme has superior high-temperature deformation resistance and water damage resistance compared to the fresh mixtures in Comparative Examples 1 and 2.

[0056] For this method, core samples were taken from the pavements repaired in Comparative Examples 1 and 2 to test the pavement compaction degree; simultaneously, rebound deflection values ​​were measured to evaluate the structural bearing capacity. The test results are as follows:

[0057] compaction Rebound deflection value This method 98.2 32.4 Comparative Example 1 97.1 28.6 Comparative Example 2 97.3 33.1

[0058] It can be seen that this method has a high degree of compaction. This is because the recycled mixture is prepared from waste asphalt pavement material. The waste material is mixed twice. The old aggregate in the waste material has reduced angularity during service, milling, and mixing. The frictional resistance is small and it is easy to compact during the compaction process. At the same time, this method uses self-compacting recycled concrete to pour the base layer. It has a low water-cement ratio, high fluidity, and is easy to compact, which effectively solves the problem of poor compaction due to the limited boundary of the pipeline trench working surface on the construction site.

[0059] The construction operation cycle and economic benefits of the three construction methods were statistically analyzed. The statistical and analytical results are as follows:

[0060] This method involves curing the self-compacting concrete base course for 5 hours (1. The old asphalt pavement material removed during pipeline excavation is recycled, reducing the amount of asphalt and aggregate used, and avoiding the land occupation and environmental pollution caused by the waste of excavated materials; 2. The base course curing time is short, allowing for earlier traffic opening and reducing urban congestion).

[0061] Comparative Example 1: Cement-stabilized crushed stone base course curing for 7 days (1. Old asphalt pavement materials removed during pipeline excavation need to be discarded or disposed of, causing environmental impact or incurring disposal costs; 2. Long base course curing time affects residents' travel and increases urban congestion).

[0062] Comparative Example 2: C20 plain concrete base course cured for 7 days (1. Old asphalt pavement materials removed during pipeline excavation need to be discarded or disposed of, causing environmental impact or incurring disposal costs; 2. Long base course curing time affects residents' travel and increases urban congestion factors)

[0063] Therefore, this method has a short base curing time, reduces the amount of asphalt and stone used, and avoids the waste of excavated materials occupying land and polluting the environment.

[0064] In the description of this specification, references to terms such as "example," "embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0065] Of course, the present invention is not limited to the above-described embodiments. Those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for repairing asphalt pavement after pipeline excavation, characterized in that: Includes the following steps: S1: Based on the location of the pipeline design, the original road structure is milled and crushed in layers. The crushed original road surface layer produces old asphalt pavement waste material, and the crushed original road base layer produces old base layer waste material. S2: Excavate a trench downward from the top surface of the original roadbed for laying the pipeline, lay the pipeline, and fill the trench to the top surface of the original roadbed with backfill material, the backfill material being located on the outer periphery of the pipeline; S3: The waste material from the old base layer generated in step S1 is washed with water, crushed by a crusher, screened, and mixed into recycled aggregate. Then, water, sand, cement, and water-reducing agent are added and mixed at room temperature to prepare self-compacting concrete. The particle size of the recycled aggregate is 5-31.5mm, the cement is P.O42.5 grade fast-setting and fast-hardening early-strength cement, and the water-reducing agent is polycarboxylate water-reducing agent. The mass ratio of cement, sand, recycled aggregate, water, and polycarboxylate water-reducing agent is 1:2:3:0.6:0.

06. S4: By pouring the self-compacting concrete, a self-compacting recycled concrete base layer is formed above the backfill material; the thickness of the self-compacting recycled concrete base layer is 25-35cm. After the self-compacting recycled concrete base layer has been cured for 5 hours, a tack coat, a slurry seal coat, and a fiberglass geogrid are sprayed sequentially from bottom to top on the top of the self-compacting recycled concrete base layer. The fiberglass geogrid is connected to the original road base layer using a fixing device. The tack coat includes PC-2 type cationic emulsified asphalt, and the dosage of PC-2 type cationic emulsified asphalt is 0.7-1.5L / m2. The slurry seal coat includes ES-2 type emulsified asphalt, and the dosage of ES-2 type emulsified asphalt is 0.9-1.0L / m2. The longitudinal and transverse strengths of the fiberglass geogrid are both 50-80KN / m, and the elongation at break is not greater than 3%. S5: The old asphalt pavement waste material generated in step S1 is crushed and screened into a first waste material with a small particle size and a second waste material with a large particle size; the heating temperature of the first waste material is 150℃, and before asphalt mixing, a recycling agent is sprayed on the surface of the first waste material, and the amount of recycling agent is 4-7% of the weight of the first waste material; S6: Heat the first waste material, add the first aggregate, add asphalt and recycling agent and mix to form a medium-grained recycled asphalt mixture. Lay the medium-grained recycled asphalt mixture on top of the self-compacting recycled concrete base layer to form a recycled medium-grained asphalt concrete surface layer. S7: Heat the second waste material, add the second aggregate, add asphalt and recycling agent and mix to form a fine-grained recycled asphalt mixture. Lay the fine-grained recycled asphalt mixture on top of the recycled medium-grained asphalt concrete surface layer to form a recycled fine-grained asphalt concrete surface layer, thus completing the road repair.

2. The method for repairing asphalt pavement through pipeline excavation according to claim 1, characterized in that: In step S2, a crushed stone cushion layer is laid on top of the backfill material. The crushed stone cushion layer is located at the top of the trench. The self-compacting recycled concrete base layer is located on top of the crushed stone cushion layer. The thickness of the crushed stone cushion layer is 15-20cm. The backfill material includes crushed stone chips or medium-coarse sand. The compaction degree of the backfill material after filling is not less than 95%.

3. The method for repairing asphalt pavement through pipeline excavation according to claim 1, characterized in that: The fixing device includes U-shaped nails. The fiberglass grid is located above the self-compacting recycled concrete base layer. The outer periphery of the fiberglass grid extends above the original road base layer. The U-shaped nails connect the outer periphery of the fiberglass grid to the original road base layer. The lateral spacing between adjacent U-shaped nails is 20m, and the longitudinal spacing is 100cm.

4. The method for repairing asphalt pavement through pipeline excavation according to claim 1, characterized in that: In step S6, the recycled medium-grained asphalt concrete surface layer is located on top of the fiberglass grid. The thickness of the recycled medium-grained asphalt concrete surface layer is 6 cm. The particle size of the first aggregate is 0-19.5 mm. The heating temperature of the first aggregate is 180 °C. The heating temperature of the asphalt is 150 °C.

5. The method for repairing asphalt pavement after pipeline excavation according to claim 1, characterized in that: In step S6, tack coat oil is sprayed on top of the reclaimed granular asphalt concrete surface layer, the tack coat oil is PC-3 type emulsified asphalt, the amount of the tack coat oil is 0.3-0.6L / m 2 .

6. The method for repairing asphalt pavement through pipeline excavation according to claim 5, characterized in that: In step S7, the heating temperature of the second waste material is 150°C. Before asphalt mixing, a recycling agent is sprayed onto the surface of the second waste material. The amount of the recycling agent is 4-7% of the weight of the second waste material. The fine-grained recycled asphalt mixture is laid on top of the tack coat and the recycled fine-grained asphalt concrete surface layer is rolled. The thickness of the recycled fine-grained asphalt concrete surface layer is 4cm. The particle size of the second aggregate is 0-13.2mm. The heating temperature of the second aggregate is 180°C, and the heating temperature of the asphalt is 150°C.

7. The method for repairing asphalt pavement through pipeline excavation according to claim 1, characterized in that: It also includes S10: smoothing and shaping of recycled fine-grained asphalt concrete surface layer.

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