A disposal method for asphalt pavement in-situ regeneration, a test piece preparation method, and a test piece evaluation method

Abstract

The application discloses a kind of asphalt pavement in situ regeneration disposal methods, mainly using the in situ regeneration stick with composite regenerant is placed in the asphalt pavement needing repair, and using heating method makes composite regenerant and waste asphalt react, to complete the in situ repair of asphalt pavement, reduce transportation cost, save energy, shorten construction period, and reduce the influence on environment;It is also disclosed that test piece preparation and test piece evaluation, sampling test is carried out to the in situ regenerated asphalt pavement, and the test piece sample and the reference sample are subjected to softening point test, PG grading test, ductility test and low-temperature bending beam rheological test, to accurately know the softening point, ductility, rut factor and creep rate of the test piece sample and the reference sample, and comparison is made, to obtain the quality and performance of regenerated asphalt, and then the diffusion of composite regenerant is calculated, to further know the regeneration effect of regenerated asphalt pavement.

Description

Technical Field

[0001] This invention belongs to the technical field of road repair, and particularly relates to a treatment method for in-situ regeneration of asphalt pavement, a test specimen preparation method, and a test specimen evaluation method. Background Technology

[0002] In China, there are a vast number of asphalt roads, covering urban roads, highways, rural roads, and other areas. Asphalt is a common road paving material. Due to factors such as traffic flow and climate change, the lifespan of asphalt roads is limited. However, regular inspection and maintenance can extend their lifespan and ensure safe passage.

[0003] The main raw material for asphalt roads is asphalt mixture. Traditional methods of asphalt mixture production and use typically rely on fresh raw materials, including petroleum-refined asphalt and natural aggregates. However, with the increasing demand for asphalt mixtures and the pursuit of sustainable development, the reuse and recycling of waste asphalt mixtures has become an important technological and economic trend. The reuse and recycling of waste asphalt mixtures refers to the recycling and reprocessing of waste asphalt pavement materials for use in new asphalt concrete production and road construction. This reduces resource waste, lowers environmental pollution, and also reduces the use and cost of new materials.

[0004] Several asphalt mixture recycling technologies already exist, including hot recycling (heating crushed waste asphalt pavement particles in hot recycling equipment to soften the asphalt, then adding appropriate amounts of new asphalt and additives to regenerate and produce recycled asphalt concrete that meets specifications), cold recycling (using specialized machinery to recycle waste pavement on-site when the pavement damage is minor), and chemical recycling (adding modifiers and additives during the recycling process to improve the performance and quality of the recycled asphalt concrete). These methods often require transporting waste asphalt mixtures to specialized recycling plants for processing, and then returning the recycled mixture to the construction site for use. This not only increases costs and energy consumption but may also lead to environmental pollution and traffic congestion.

[0005] Therefore, the increased cost and high energy consumption of existing waste asphalt mixture treatment methods, as well as the need for newly proposed waste asphalt mixture treatment methods to ensure that the quality and performance of recycled mixtures meet the requirements of road construction, are technical problems that need to be solved by those skilled in the art. Summary of the Invention

[0006] One of the objectives of this invention is to address the problems of increased processing costs and high energy consumption associated with the disposal of existing waste asphalt mixtures. This invention provides a method for in-situ regeneration of asphalt pavements, a method for preparing test specimens, and a method for evaluating test specimens, enabling in-situ regeneration of asphalt pavements, thereby reducing processing costs and energy consumption.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution: A method for in-situ recycling of asphalt pavement includes the following steps: S1. Preparation of in-situ regeneration rods; S2. Drill holes in the asphalt pavement and install and fix in-situ recycling rods in the holes; S3. Install temperature sensors in the surface layer of the asphalt pavement and lay wire mesh on the asphalt pavement. S4. Microwave heating is applied to the area where the wire mesh is laid, and heat preservation treatment is performed. S5. Fill the drilled holes where in-situ recycling rods are installed, microwave heat the asphalt pavement again, and compact the asphalt pavement to complete the in-situ recycling treatment of the asphalt pavement.

[0008] Further, step S1 includes the following sub-steps: S1-1. Mix the regenerator, diffusion aid, and penetration aid in a ratio of 3:1:1 and place them in a clean container. Use a mixer to stir the mixture evenly to obtain a composite regenerator. S1-2. Pour the composite regenerator into the silicone mold until it overflows, then place the silicone mold containing the composite regenerator in a freezer at -18°C and freeze for 24 hours. S1-3. After freezing and storage, some of the composite regenerant overflows. The overflowing solid composite regenerant is cut off along the opening of the silicone mold to ensure that the upper surface is flat. S1-4. Then, remove the solid composite regenerator from the silicone mold and place it into the metal rod mold. Seal the top surface with a lid to obtain an in-situ regenerated rod. Further, step S2 specifically involves: marking the drilling locations on the asphalt pavement, drilling holes, cleaning the drill cuttings from the inner wall and bottom of the holes, fixing the pre-prepared in-situ regeneration rods in the drilled holes, and evenly sprinkling activator powder inside the holes. Further, step S3 includes the following sub-steps: S3-1. In the area where the in-situ recycling rods are distributed, one temperature sensor is laid out laterally in the center of the lane and one temperature sensor is laid out every 5 meters longitudinally. Circular holes with a diameter of 2-3 cm and a depth of 10 cm are drilled in the surface layer of the asphalt pavement, and the temperature sensors are placed in the circular holes. S3-2. Lay heated wire mesh on the surface of the asphalt pavement, then fix the ends of the wire mesh and place counterweight bags on the wire mesh. Further, step S4 specifically includes: The counterweight bags on the surface of the recycled wire mesh are recycled. 300-500ml of water is poured into each hole where the in-situ recycling rod is placed. A microwave heating vehicle is used to heat the road surface in the area where the wire mesh is laid. When the temperature sensor of the asphalt pavement surface structure detects that the road surface temperature reaches above 60℃, the microwave heating vehicle stops. Heat insulation cloth is used to cover and repair the surface. The heat insulation cloth is then sealed and fixed with rivets around its perimeter. At the same time, sandbags preheated to 60℃-90℃ are placed at the location where the in-situ recycling rod is laid. The composite recycling agent of the in-situ recycling rod diffuses in a sealed manner.

[0009] Further, step S5 includes the following sub-steps: After S5-1 and 3h-6h, remove the heat insulation cloth and sandbags, take out the in-situ recycling rod from the hole, pour the remaining undiffused in-situ recycling rod's composite recycling agent into the premixed asphalt mixture and mix it thoroughly, then fill the hole and compact the filled area. S5-2. Use a microwave heating vehicle to heat the compacted road surface by driving. When the temperature sensor of the asphalt pavement surface structure detects that the road surface temperature reaches above 90°C, stop the microwave heating vehicle from driving. S5-3. Compact the asphalt pavement and let it stand for 12-24 hours after compaction.

[0010] Another objective of this invention is to make the in-situ recycling of asphalt pavement feasible. Therefore, a test specimen preparation method and a test specimen evaluation method are proposed, which can ensure that the quality and performance of the recycled mixture meet the requirements of road construction.

[0011] The above-mentioned objective of this invention is achieved through the following technical solution: A method for preparing test specimens for in-situ regeneration of asphalt pavement, comprising sampling the aforementioned in-situ regenerated asphalt pavement, including the following steps: (1) Determine the sampling location After the asphalt pavement is recycled in situ, at least one hole that was originally fixed with an in-situ recycling rod is randomly selected. Taking the center point of the single in-situ recycling rod as the center A, circular marking lines with radii of 3dm, 6dm, 9dm, 12dm and 15dm are drawn with a marker pen. The circle with a radius of 15dm is subdivided into 5 arc-shaped areas, which are named Area I, Area II, Area III, Area IV and Area V respectively. These 5 areas are used as sampling locations. (2) Cutting and sampling Five arc-shaped sampling pieces were cut out sequentially from the inside to the outside of regions I, II, III, IV and V using a cutting machine. The cutting depth was the length of the in-situ regeneration rod. (3) Obtain test specimen samples Five arc-shaped sampling pieces were separated by centrifugation to obtain the corresponding asphalt binder, resulting in five arc-shaped test specimen samples.

[0012] A method for evaluating test specimens of in-situ regeneration of asphalt pavement, which uses the asphalt binder of the five arc-shaped test specimen samples obtained above for evaluation, includes the following steps: 1) Set up a reference group. Without in-situ treatment of the asphalt pavement, cut and centrifuge the asphalt binder of the reference group to obtain a reference sample. 2) Evaluation tests are conducted on the asphalt binder of the test specimen and the asphalt binder of the reference sample. The evaluation tests include softening point test, PG classification test, ductility test and low temperature bending beam rheological test to obtain test data of softening point, ductility, rutting factor and creep rate. The softening point, ductility, rutting factor and creep rate are the evaluation indicators. 3) Plot regression curves based on experimental data, calculate weights, and then define the comprehensive regeneration evaluation index O; 4) Determine the relevant technical parameters of the optimal diffusion zone, the attenuation zone, and the degradation zone to obtain a comprehensive evaluation of the regeneration effect.

[0013] Furthermore, step 3) of plotting the regression curve based on the experimental data includes the following sub-steps: 3-1) For the softening point test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regeneration rod is used as the abscissa. The ratio D of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample is used. i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, D1), (6, D2), (9, D3), (12, D4), and (15, D5). Based on the data from these 5 coordinate points, we obtain the linear regression equation for the softening point: y=k. 软 x+b软 D i The calculation formula is: , Among them, D i The ratio of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample; 3-2) For the ductility test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio M of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference sample is... i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, M1), (6, M2), (9, M3), (12, M4), and (15, M5). Based on the data from these 5 coordinate points, we obtain the linear regression equation y=k. 延 x+b 延 M i The calculation formula is: , Among them, M i The ratio of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference sample; 3-3) For the PG grading test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio N of the absolute value of the change in rutting factor of the five arc-shaped test specimens to the rutting factor of the reference sample is used. i Using (i=1~5) as the ordinate, we obtain 5 coordinate points (3, N1), (6, N2), (9, N3), (12, N4), and (15, N5). Based on the data from these 5 coordinate points, we obtain the linear regression equation for the rut factor: y=k 车 x+b 车 N i The calculation formula is: , Where, N i The ratio of the absolute value of the rutting factor change of the five arc-shaped test specimens to the rutting factor of the reference sample; 3-4) For the low-temperature bending beam rheological test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio H of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference sample is... i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, H1), (6, H2), (9, H3), (12, H4), and (15, H5). Based on the data from these 5 coordinate points, we obtain the linear regression equation for the creep rate: y=k 蠕 x+b 蠕 Hi The calculation formula is:

[0014] Among them, H i The value is the ratio of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference specimen.

[0015] Furthermore, step 3) weight calculation includes the following sub-steps: 3-5) For each regression equation, plot the corresponding straight line L on the same coordinate system. i (i=1~4), draw two perpendicular lines to the X-axis, labeled L. a L b Two perpendicular lines L to the X-axis a L b Passing through points (3, 0) and (15, 0) respectively, L i (i=1~4), L a L b The area of ​​the trapezoid formed by the x-axis and the x-axis is denoted as S. i-a-b-X (i=1~4), S 1-a-b-X S 2-a-b-X S 3-a-b-X and S 4-a-b-X These correspond to softening point, ductility, rutting factor, and creep rate, respectively. 3-6) Calculate the area S of the trapezoid. i-a-b-X (i=1~4), calculate the area S of each trapezoid. i-a-b-X The weights of each evaluation index (i=1~4) are calculated to obtain the weight G. i (i=1~4), G1, G2, G3 and G4 correspond to the softening point evaluation index, ductility evaluation index, rutting factor evaluation index and creep rate evaluation index, respectively. The weight G1 of the softening point index is calculated as follows: ; The formula for calculating the weight G2 of the ductility index is as follows: ; The formula for calculating the weight G3 of the rut factor index is as follows: ; The formula for calculating the weight G4 of the creep rate index is as follows: .

[0016] Furthermore, step 3) defines the comprehensive regeneration evaluation index O. i O i(i=1~4) is the sum of the products of the results of the four evaluation indicators and their corresponding weights, representing the comprehensive regeneration evaluation index O. i The calculation formula is: , Among them, i=1~5, O i D is the comprehensive regeneration evaluation index for areas I-V. i The ratio of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample, M i The ratio of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference specimen, N i The ratio of the absolute value of the rutting factor change of the five arc-shaped test specimens to the rutting factor of the reference specimen, H i G1 is the ratio of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference sample. G1 is the weight of the softening point index, G2 is the weight of the ductility index, G3 is the weight of the rutting factor index, and G4 is the weight of the creep rate index.

[0017] Further, step 4) determining the relevant technical parameters of the optimal diffusion region, the attenuation region, and the degradation region includes the following sub-steps: 4-1) Using the radial distance from the arc point of each of the five arc-shaped test specimens to the center of the in-situ regeneration rod as the abscissa, the comprehensive regeneration evaluation index O is calculated. i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, O1), (6, O2), (9, O3), (12, O4), and (15, O5). Based on the data from these 5 coordinate points, we obtain the linear regression equation y=k O x+b O ; 4-2) Based on the regression equation y=k O x+b O Calculate the maximum value O of the ordinate of the equation. max Calculate the maximum value of the ordinate O. max The x-coordinate corresponding to 70% is x1, and the maximum value of the y-coordinate is O. max The x-coordinate corresponding to 40% is x2, and the maximum value of the y-coordinate is O. max The x-coordinate corresponding to 10% is x3; 4-3) Using the center point of a single in-situ regeneration rod as the center, draw circular marking lines with radii of x1, x2, and x3 through the center, respectively, to obtain three circles with radii of x1, x2, and x3. The circular area with radius x1 is marked as region VII, the annular area with radius in the range of [x1, x2] is marked as region VIII, and the annular area with radius in the range of [x2, x3] is marked as region IX. Define region VII as the optimal diffusion region, region VIII as the attenuation region, and region IX as the degradation region. 4-4) Calculate the area S1 of the optimal diffusion zone, the area S2 of the attenuation zone, and the area S3 of the deterioration zone. Define the first diffusion coefficient K1 and the second diffusion coefficient K2 of the composite regenerator. K1 is the ratio of the area S1 of the optimal diffusion zone to the area S2 of the attenuation zone, and K2 is the ratio of the area S1 of the optimal diffusion zone to the area S3 of the deterioration zone. The formula for calculating K1 is: , Wherein, K1 is the first diffusion coefficient of the composite regenerator, S1 is the area of ​​the optimal diffusion region, and S2 is the area of ​​the attenuation region; The formula for calculating K2 is:

[0018] Wherein, K2 is the second diffusion coefficient of the composite regenerator, S1 is the area of ​​the optimal diffusion zone, and S3 is the area of ​​the deterioration zone.

[0019] The beneficial effects of this invention are as follows: (1) A method for in-situ repair of asphalt pavement was designed. The method mainly involves placing an in-situ recycling rod with a composite recycling agent into the asphalt pavement to be repaired, and using a heating method to make the composite recycling agent react with the waste asphalt, thereby completing the in-situ repair of the asphalt pavement, reducing transportation costs, saving energy, shortening the construction period, and reducing the impact on the environment. (2) Test specimen preparation and evaluation were carried out. The in-situ recycled asphalt pavement was sampled and tested. The test specimen samples and reference samples were subjected to softening point test, PG classification test, ductility test and low temperature bending beam rheological test to accurately determine the softening point, ductility, rutting factor and creep rate of the test specimen samples and reference samples. The quality and performance of recycled asphalt were obtained by comparison. Then, the diffusion of composite recycling agent was calculated to determine the recycling effect of recycled asphalt pavement. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the metal mold for the in-situ regeneration rod in the in-situ regeneration method for asphalt pavement of the present invention. Figure 2 This is a diagram showing the steel wire mesh layout of a method for in-situ regeneration of asphalt pavement according to the present invention. Figure 3 This is a diagram illustrating the circulating travel scheme of a microwave heating vehicle for an in-situ regeneration method of asphalt pavement according to the present invention. Figure 4 This is a schematic diagram of the cutting and sampling process for preparing test specimens for in-situ regeneration of asphalt pavement according to the present invention. Figure 5 This is a schematic diagram of the regression curve of the softening point change ratio in the test specimen evaluation method of the in-situ regeneration of asphalt pavement according to the present invention. Figure 6 This is a schematic diagram of the regression curve of the ductility change ratio in the test specimen evaluation method of the in-situ regeneration of asphalt pavement according to the present invention. Figure 7 This is a schematic diagram of the regression curve of the rutting factor change ratio in the test specimen evaluation method of the in-situ regeneration of asphalt pavement according to the present invention. Figure 8 This is a schematic diagram of the creep rate change percentage regression curve of the test specimen evaluation method for in-situ regeneration of asphalt pavement according to the present invention. Figure 9 This is a schematic diagram illustrating the calculation of the area under the regression curve of the evaluation index for the test specimen evaluation method of in-situ regeneration of asphalt pavement according to the present invention. Figure 10 This is a schematic diagram of the O regression curve of the comprehensive regeneration evaluation index of the test specimen evaluation method for in-situ regeneration of asphalt pavement according to the present invention. Figure 11 This is a schematic diagram illustrating the determination of the optimal diffusion zone, attenuation zone, and deterioration zone ordinates for the test specimen evaluation method of in-situ regeneration of asphalt pavement according to the present invention. Figure 12 This is a schematic diagram showing the optimal diffusion zone, attenuation zone, and deterioration zone areas of the test specimen evaluation method for in-situ regeneration of asphalt pavement according to the present invention. Figure 13 This is a flowchart of a method for in-situ regeneration of asphalt pavement according to the present invention. Detailed Implementation

[0021] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0022] Example 1

[0023] A method for in-situ recycling of asphalt pavement includes the following steps: S1. Preparation of in-situ regeneration rods, including the following sub-steps: S1-1. Mix the regenerator, diffusion aid, and penetration aid in a ratio of 3:1:1 and place them in a clean container. Use a mixer to stir the mixture evenly to obtain a composite regenerator, which is in the form of a slurry. S1-2. Pour the composite regenerator into the silicone mold until it overflows. Place the silicone mold containing the composite regenerator in a freezer at -18°C and freeze for 24 hours to obtain a solid composite regenerator. S1-3. After frozen storage, some of the composite regenerant overflows. Use an electric saw to cut off the overflowing solid composite regenerant along the opening of the silicone mold to ensure that the upper surface is flat. S1-4. Then, the solid composite regenerator is removed from the silicone mold and placed into the metal rod mold. The top surface is sealed with a lid to obtain an in-situ regenerated rod. The metal rod mold is a hollow cylindrical metal mold with a closed bottom and an open top. The surrounding surface has regularly distributed holes for the regenerator to diffuse. It is worth noting that the metal mold is made of aluminum, and the mold size can be in the range of 5-10cm inner diameter and 10-15cm height, for reference. Figure 1 In this embodiment 1, the mold has an inner diameter of 8cm and a height of 12cm. The diameter of the holes around the metal mold is 1cm. The silicone mold is mainly used for the preparation of composite regenerative agent solids. Its size is the same as that of the metal rod mold. The electric saw is a rechargeable electric chainsaw.

[0024] S2. Drill holes in the asphalt pavement and install and fix in-situ recycling rods in the holes. Specifically, mark the drilling positions on the asphalt pavement, drill the holes, clean the drilling slag on the inner wall and bottom of the holes, and then put the pre-prepared in-situ recycling rods into the drilled holes and fix them in place. Also, evenly sprinkle activator powder in the holes. It is worth noting that after determining the spacing of the in-situ recycling rods, the first hole drilling position A1 was marked in the center of the test pavement with a yellow marker. Subsequently, the drilling positions of other holes were marked at 5-meter intervals on all four sides of A1, and so on, until the drilling positions were marked. The drilling equipment was an electric core drill equipped with a synthetic diamond thin-walled drill bit, with a core diameter of 20cm and a core depth of 50cm. The activator powder, mainly composed of reduced iron powder, was used to subsequently react exothermically with water, promoting the penetration and diffusion of the composite recycling agent within the asphalt pavement.

[0025] S3. Install temperature sensors in the surface layer of the asphalt pavement and lay wire mesh on the asphalt pavement, including the following sub-steps: S3-1. In the area where the in-situ recycling rods are distributed, one temperature sensor is laid out laterally in the center of the lane and one temperature sensor is laid out every 5 meters longitudinally. Circular holes with a diameter of 2-3 cm and a depth of 10 cm are drilled in the surface layer of the asphalt pavement, and the temperature sensors are placed in the circular holes. It's worth noting that a circular hole with a diameter of 3cm and a depth of 10cm is drilled at the designated location using an electric drill. Since the temperature sensor needs to be connected to a power source, a shallow groove with a width of 2.4cm and a depth of 3cm needs to be cut transversely on one side of the circular hole. The connecting wire is then laid in the shallow groove and led out beyond the road width. Cold patch material is then filled into the circular hole and the shallow groove and compacted. Furthermore, the temperature sensor is a thermocouple temperature sensor with a sensing range of 20-200℃ and a testing accuracy of 0.1℃. After installation, a reading device is used to read the road surface temperature data to ensure data accuracy.

[0026] S3-2, reference Figure 2 A heated wire mesh is laid on the surface of the asphalt pavement, then the ends of the wire mesh are fixed, and a counterweight bag is placed on the wire mesh. It is worth noting that before laying the heated wire mesh, the damaged sections of the road surface need to be repaired and maintained to ensure the smoothness of the asphalt pavement. The heated wire mesh is made of hot-dip galvanized iron wire or zinc-aluminum alloy wire, which is machine-woven into a hexagonal double-twisted metal mesh by hot-dip galvanized anti-corrosion treatment, with transverse reinforcing bars woven into the mesh at certain intervals. The diameter of the steel wire can be in the range of 2.0-2.7mm, the diameter of the reinforcing bars can be in the range of 3.4-5mm, and the tensile strength of the steel wire should not be less than 38kg / m. 2 In this embodiment, the wire diameter is 2.5mm, the reinforcing bar diameter is 35mm, and the wire tensile strength is 50kg / m. 2 A counterweight bag is a structural counterweight bag used to provide stability and support. The main material is a wear-resistant, waterproof, and weather-resistant fiber bag or cloth bag. The filling includes sand, water, metal particles, etc. The weight of a single bag is not less than 25kg. Placing a counterweight bag can prevent the wire mesh from warping or wrinkling.

[0027] S4. Microwave heating and heat preservation treatment are applied to the area where the wire mesh is laid. The counterweight bags on the surface of the recycled wire mesh are recycled. 300-500ml of water is poured into each hole where the in-situ recycling rod is placed. A microwave heating vehicle is used to heat the road surface in the area where the wire mesh is laid. When the temperature sensor of the asphalt pavement surface structure detects that the road surface temperature reaches above 60℃, the microwave heating vehicle stops. Heat insulation cloth is used to cover and repair the surface. The heat insulation cloth is then sealed and fixed with rivets around its perimeter. At the same time, sandbags preheated to 60℃-90℃ are placed at the location where the in-situ recycling rod is laid. The composite recycling agent of the in-situ recycling rod diffuses in a sealed manner.

[0028] It is worth noting that 400ml of water is poured into each hole. Adding water activates the activator, releasing heat and accelerating the transformation of the recycling agent from solid to liquid, while also promoting the penetration and diffusion of the recycling agent in the asphalt pavement surface layer. Microwave heating is used to raise the surface layer temperature, thereby accelerating the diffusion of the recycling agent into the surface asphalt mixture. The microwave heating vehicle is an integrated maintenance vehicle for asphalt pavement using microwave technology, emitting microwaves at a frequency of 2450MHz. The vehicle's travel speed is set to 5-10km / h. This embodiment refers to... Figure 3 The microwave heating vehicle's travel speed is set to 8 km / h. The vehicle travels in a cyclical manner between different lanes, using a single lane as a travel unit, to ensure that the regenerated road surface is heated evenly. The heat insulation cloth is sealed and fixed with rivets around its perimeter to prevent heat loss from the road surface. The heat insulation cloth is one of glass fiber cloth, ceramic fiber cloth, or polyester fiber cloth, with a thermal conductivity of 0.15 W / (m·K). The sandbags are square sandbags, specifically 70°C, and their main filling material is fine sand or quartz sand with high heat capacity. The sandbags are usually made of heat-resistant fabric, specifically cotton, linen, or canvas.

[0029] S5. Fill the drilled holes where in-situ recycling rods are installed, microwave heat the asphalt pavement again, and compact the asphalt pavement to complete the in-situ recycling treatment of the asphalt pavement.

[0030] Further, step S5 includes the following sub-steps: After S5-1 and 5h, remove the heat insulation cloth and sandbags, take out the in-situ recycling rod from the hole, pour the remaining undiffused in-situ recycling rod's composite recycling agent into the premixed asphalt mixture and mix it thoroughly, then fill the hole and compact the filled area. S5-2. Use a microwave heating vehicle to heat the compacted road surface by driving. When the temperature sensor of the asphalt pavement surface structure detects that the road surface temperature reaches above 90°C, stop the microwave heating vehicle from driving. S5-3. Compact the asphalt pavement and let it stand for 24 hours after compaction.

[0031] It's worth noting that the microwave heating vehicle's travel speed is also set to 8 km / h. The vehicle travels in a cyclical pattern between different lanes, using a single lane as a travel unit. A road compactor is used to compact the filling area. A rubber-tired roller is used for initial compaction, followed by a steel-drum roller for secondary compaction. The rubber-tired roller is a compaction device used in road construction and earthwork engineering. The steel-drum roller is a heavy-duty compaction machine used in civil engineering and road construction.

[0032] In addition, the location of the holes needs to be planned. Given that the core diameter is 20cm, the distance between the in-situ recycling rods needs to be determined, and the hole location arrangement is summarized as a drilling plan. Since drilling is for inserting the in-situ recycling rods to allow them to react with the asphalt pavement material, and each in-situ recycling rod has a limiting diffusion radius during application, it is necessary to determine the limiting diffusion radius of a single in-situ recycling rod. Therefore, a preliminary experiment can be used to determine this. The road surface in the preliminary experiment is 20m long and 20m wide, the diameter of the in-situ recycling rod is 10cm, and the limiting diffusion radius of each in-situ recycling rod is preset to 2m. Therefore, the maximum distance between any two in-situ recycling rods is 4m. Thus, there are 5 holes on the road surface in the preliminary experiment. 5. A total of 25 in-situ recycling rods were used. After completing steps S1-S5 above, samples were taken for preliminary experiments, and softening point tests, PG grading tests, ductility tests, and low-temperature bending beam rheology tests (BBR) were conducted. The test data were then processed to obtain the areas of the optimal diffusion zone, attenuation zone, and deterioration zone. The specific test process can be referred to Example 3. Based on the areas of the optimal diffusion zone, attenuation zone, and deterioration zone, the limiting diffusion penetration radius was calculated. According to the preliminary experiment, the actual limiting diffusion penetration radius was 3.5m. Therefore, the drilling scheme was as follows: the maximum spacing between every two in-situ recycling rods was 7m. However, in order for the composite recycling agent of the in-situ recycling rods to fully react with the asphalt pavement, the spacing between every two in-situ recycling rods was set to 5m.

[0033] Therefore, the more complete step S2 is as follows: design a drilling scheme based on the ultimate diffusion and penetration radius of the in-situ regeneration rod, drill and lay holes in the asphalt pavement according to the drilling scheme, and install and fix the in-situ regeneration rod in the holes. Specifically, mark the drilling positions on the asphalt pavement, drill the holes, clean the drill cuttings on the inner wall and bottom of the holes, put the pre-prepared in-situ regeneration rod into the drilled holes and fix it, and evenly sprinkle activator powder in the holes.

[0034] Example 2

[0035] Reference Figure 4 A method for preparing test specimens for in-situ regeneration of asphalt pavement, comprising the following steps: Sampling of the aforementioned in-situ regenerated asphalt pavement. (1) Determine the sampling location After the asphalt pavement was recycled in situ, a hole that originally had an in-situ recycling rod was randomly selected. Taking the center point of the single in-situ recycling rod as the center A, circular marking lines with radii of 3dm, 6dm, 9dm, 12dm and 15dm were drawn with a yellow marker pen. The circle with a radius of 15dm was subdivided into 5 arc-shaped areas, which were named Area I, Area II, Area III, Area IV and Area V, respectively. These 5 areas were used as sampling locations. (2) Cutting and sampling Five arc-shaped sampling pieces were cut out sequentially from the inside to the outside of areas I, II, III, IV and V using a cutting machine. The cutting depth was the length of the in-situ regeneration rod. The cutting equipment was a laser positioning cutting machine. (3) Obtain test specimen samples Five arc-shaped sampling pieces were separated by centrifugation to obtain the corresponding asphalt binder, resulting in five arc-shaped test specimen samples.

[0036] Specifically, the asphalt binder was obtained by centrifugation separation method T0722-1993 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2019).

[0037] Example 3

[0038] A method for evaluating test specimens of in-situ regeneration of asphalt pavement, which uses the asphalt binder of the five arc-shaped test specimen samples obtained above for evaluation, includes the following steps: 1) Set up a reference group. Without in-situ treatment of asphalt pavement, cut and centrifuge the asphalt binder of the reference group to obtain a reference sample. Similarly, the asphalt binder is obtained by centrifugation separation method T0722-1993 in the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2019). 2) Evaluation tests are conducted on the asphalt binder of the test specimen and the asphalt binder of the reference sample. The evaluation tests include softening point test, PG classification test, ductility test and low temperature bending beam rheological test to obtain test data of softening point, ductility, rutting factor and creep rate. The softening point, ductility, rutting factor and creep rate are the evaluation indicators. It is worth noting that the softening point test was conducted according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2019) T0606; the ductility test was conducted according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2019) T0605, with a test temperature of 5℃; the PG grading test was conducted according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2019) T0628, with a test frequency of 10 rad / s, a starting temperature of 40℃, and a test temperature interval of 6℃; the low-temperature bending beam rheological test (BBR) was conducted according to the AASHTO-T313 specification, applying a 3-point load of 980mN±50mN for loading times of 8 seconds, 15 seconds, 30 seconds, 60 seconds, 120 seconds, and 240 seconds, with a test temperature of -18℃.

[0039] Based on softening point test, PG classification test, ductility test and low temperature bending beam rheology test (BBR), the softening point, ductility, rutting factor and creep rate of the reference sample asphalt binder specimens were measured, totaling 4 data points; the softening point, ductility, rutting factor and creep rate of the asphalt binder specimens in 5 test areas (areas I, II, III, IV and V) of the test specimens were measured, totaling 20 data points, as shown in Table 1.

[0040] Table 1 Test results of asphalt binder specimens

[0041] Asphalt aging causes the asphalt to harden and become brittle, which in turn increases the softening point and rutting factor of the asphalt sample, while reducing its ductility and creep rate.

[0042] In the above experiments, the reference sample asphalt was old asphalt that had not undergone in-situ recycling treatment, while the test sample asphalt was new asphalt that had undergone in-situ recycling treatment. According to the data in Table 1, compared with the reference sample asphalt, the test sample asphalt had a lower softening point and rutting factor, but higher ductility and creep rate. Therefore, the reference sample asphalt showed a higher degree of aging, while the test sample asphalt showed a lower degree of aging, demonstrating the effectiveness of in-situ recycling treatment in reducing the aging degree of old asphalt.

[0043] 3) Plot regression curves based on experimental data, calculate weights, and then define the comprehensive regeneration evaluation index O; 4) Determine the relevant technical parameters of the optimal diffusion zone, the attenuation zone, and the degradation zone to obtain a comprehensive evaluation of the regeneration effect.

[0044] Furthermore, step 3) of plotting the regression curve based on the experimental data includes the following sub-steps: 3-1) For the softening point test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regeneration rod is used as the abscissa. The ratio D of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample is used. i (i=1~5) as the ordinate, or reduced to Figure 5 As shown: the distance (dm) from the radial direction of the arc point in the test area to the center of the in-situ regeneration rod is used as the abscissa, and the percentage change in softening point (%) is used as the ordinate, resulting in 5 coordinate points (3, D1), (6, D2), (9, D3), (12, D4), and (15, D5). Based on the data from these 5 coordinate points, the linear regression equation for the softening point, y=k, is obtained. 软 x+b 软 D i The calculation formula is: , Among them, D i The ratio of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample; Specifically, refer to Figure 5 The five obtained coordinate points are (3, 0.14), (6, 0.124), (9, 0.083), (12, 0.071), and (15, 0.05). Based on the data from these five coordinate points, the linear regression equation for the softening point is y = -0.0078x + 0.1635, R0. 2 =0.9692, R 2 R is a statistical index used to measure the goodness of fit of a regression equation, and its value ranges from 0 to 1. 2 The closer the value is to 1, the better the fit of the regression equation, indicating that the soft-point linear regression equation has a good fit.

[0045] 3-2) For the ductility test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio M of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference sample is... i (i=1~5) as the ordinate, or reduced to Figure 6 As shown: the distance (dm) from the radial direction of the arc point in the test area to the center of the in-situ regenerated rod is used as the abscissa, and the percentage change in ductility (%) is used as the ordinate, resulting in 5 coordinate points (3, M1), (6, M2), (9, M3), (12, M4), and (15, M5). Based on the data from these 5 coordinate points, the linear regression equation for ductility, y=k, is obtained. 延 x+b 延 M i The calculation formula is: , Among them, M iThe ratio of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference sample; Specifically, refer to Figure 6 The five coordinate points obtained are (3, 1.815), (6, 1.444), (9, 0.963), (12, 0.519), and (15, 0.185). Based on the data from these five coordinate points, the linear regression equation for the ductility is obtained as y = -0.1395x + 2.2407, with R0. 2 =0.9966, R 2 R is a statistical index used to measure the goodness of fit of a regression equation, and its value ranges from 0 to 1. 2 The closer the value is to 1, the better the fit of the regression equation, indicating that the linear regression equation has a good fit.

[0046] 3-3) For the PG grading test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio N of the absolute value of the change in rutting factor of the five arc-shaped test specimens to the rutting factor of the reference sample is used. i (i=1~5) as the ordinate, or reduced to Figure 7 As shown: the distance (dm) from the radial point of the test area arc to the center of the in-situ regeneration rod is used as the abscissa, and the percentage change in rutting factor (%) is used as the ordinate, resulting in 5 coordinate points (3, N1), (6, N2), (9, N3), (12, N4), and (15, N5). Based on the data from these 5 coordinate points, the linear regression equation for the rutting factor, y=k, is obtained. 车 x+b 车 The formula for calculating Ni is: , Where, N i The ratio of the absolute value of the rutting factor change of the five arc-shaped test specimens to the rutting factor of the reference sample; Specifically, refer to Figure 7 The five coordinate points obtained are (3, 0.791), (6, 0.727), (9, 0.632), (12, 0.367), and (15, 0.33). Based on the data from these five coordinate points, the linear regression equation for the rut factor is y = -0.0427x + 0.954, with R0. 2 =0.9331, R 2 R is a statistical index used to measure the goodness of fit of a regression equation, and its value ranges from 0 to 1. 2 The closer the value is to 1, the better the fit of the regression equation, indicating that the linear regression equation for the rut factor has a good fit.

[0047] 3-4) For the low-temperature bending beam rheological test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio H of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference sample is... i (i=1~5) as the ordinate, or reduced to Figure 8 As shown: the distance (dm) from the radial direction of the arc point in the test area to the center of the in-situ regeneration rod is used as the abscissa, and the percentage change in creep rate (%) is used as the ordinate, resulting in five coordinate points: (3, H1), (6, H2), (9, H3), (12, H4), and (15, H5). Based on the data from these five coordinate points, the linear regression equation y=k is obtained. 蠕 x+b 蠕 H i The calculation formula is:

[0048] Among them, H i The value is the ratio of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference specimen.

[0049] Specifically, refer to Figure 8 The five coordinate points obtained are (3, 0.25), (6, 0.214), (9, 0.143), (12, 0.071), and (15, 0.036). Based on the data from these five coordinate points, the linear regression equation for the creep rate is obtained as y = -0.019x + 0.3141, R0. 2 =0.9843, R 2 R is a statistical index used to measure the goodness of fit of a regression equation, and its value ranges from 0 to 1. 2 The closer the value is to 1, the better the fit of the regression equation, indicating that the linear regression equation for creep rate has a good fit.

[0050] Because some performance indicators of asphalt improve while others decrease after recycling, the evaluation of the recycling effect can be obtained by using the test data of a reference sample asphalt as baseline data and calculating the ratio of the absolute value of the change in test data of the test specimen asphalt before and after recycling to the test data of the reference sample asphalt.

[0051] Furthermore, step 3) weight calculation includes the following sub-steps: 3-5) For each regression equation, refer to Figure 9 Plot the line L corresponding to this equation on the same coordinate system. i (i=1~4), draw two perpendicular lines to the X-axis, labeled L. a L b Two perpendicular lines L to the X-axis aL b Passing through points (3, 0) and (15, 0) respectively, L i (i=1~4), L a L b The area of ​​the trapezoid formed by the x-axis and the x-axis is denoted as S. i-a-b-X (i=1~4), S 1-a-b-X S 2-a-b-X S 3-a-b-X and S 4-a-b-X These correspond to softening point, ductility, rutting factor, and creep rate, respectively. 3-6) Calculate the area S of the trapezoid. i-a-b-X (i=1~4), calculate the area S of each trapezoid. i-a-b-X The weights of each evaluation index (i=1~4) are calculated to obtain the weight G. i (i=1~4), G1, G2, G3 and G4 correspond to the softening point evaluation index, ductility evaluation index, rutting factor evaluation index and creep rate evaluation index, respectively. The weight G1 of the softening point index is calculated as follows: ; The formula for calculating the weight G2 of the ductility index is as follows: ; The formula for calculating the weight G3 of the rut factor index is as follows: ; The formula for calculating the weight G4 of the creep rate index is as follows: .

[0052] Calculate the area S enclosed by the line graphs of each indicator. i-a-b-X (i=1~4), the S values ​​of each indicator i-a-b-X The weights of each evaluation index (i=1~4) are calculated to obtain the weight G. i (i=1~4), see Table 2.

[0053] Table 2. Area and weight of evaluation indicators

[0054] Based on the area enclosed by the line graphs of each evaluation index in Table 2 and their respective weights, it can be seen that the rutting factor and ductility are important indicators for evaluating the regeneration effect of in-situ regeneration rods.

[0055] Furthermore, step 3) defines the comprehensive regeneration evaluation index O. i O i (i=1~4) is the sum of the products of the results of the four evaluation indicators and their corresponding weights, representing the comprehensive regeneration evaluation index O.i The calculation formula is: , Among them, i=1~5, O i D is the comprehensive regeneration evaluation index for areas I-V. i The ratio of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample, M i The ratio of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference specimen, N i The ratio of the absolute value of the rutting factor change of the five arc-shaped test specimens to the rutting factor of the reference specimen, H i G1 is the ratio of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference sample. G1 is the weight of the softening point index, G2 is the weight of the ductility index, G3 is the weight of the rutting factor index, and G4 is the weight of the creep rate index.

[0056] The comprehensive regeneration evaluation index O for each test specimen is shown in Table 3.

[0057] Table 3. Results of the comprehensive regeneration evaluation index of test specimens in each region.

[0058] Further, step 4) determining the relevant technical parameters of the optimal diffusion region, the attenuation region, and the degradation region includes the following sub-steps: 4-1) Using the radial distance from the arc point of each of the five arc-shaped test specimens to the center of the in-situ regeneration rod as the abscissa, the comprehensive regeneration evaluation index O is calculated. i (i=1~5) as the ordinate, or reduced to Figure 10 As shown: the distance (dm) from the radial point of the arc in the test area to the center of the in-situ regenerated rod is used as the abscissa, and the percentage change of the comprehensive regeneration evaluation index (%) is used as the ordinate, resulting in 5 coordinate points (3, O1), (6, O2), (9, O3), (12, O4), and (15, O5). Based on the data from these 5 coordinate points, the linear regression equation for the comprehensive regeneration evaluation index, y=k, is obtained. O x+b O ; Specifically, refer to Figure 10 The five coordinate points are (3, 1.277), (6, 1.049), (9, 0.746), (12, 0.411), and (15, 0.212). Based on the data from these five coordinate points, the linear regression equation for the comprehensive regeneration evaluation index is y = -0.0922x + 1.5694, R0. 2 =0.9939, R 2R is a statistical index used to measure the goodness of fit of a regression equation, and its value ranges from 0 to 1. 2 The closer the value is to 1, the better the fit of the regression equation, indicating that the linear regression equation of the comprehensive regeneration evaluation index has a good fit.

[0059] 4-2) Based on the regression equation y=k O x+b O Calculate the maximum value O of the ordinate of the equation. max Calculate the maximum value of the ordinate O. max The x-coordinate corresponding to 70% is x1, and the maximum value of the y-coordinate is O. max The x-coordinate corresponding to 40% is x2, and the maximum value of the y-coordinate is O. max The x-coordinate corresponding to 10% is x3; Specifically, refer to Figure 11 Based on the linear regression equation y = -0.0922x + 1.5694 of the comprehensive regeneration evaluation index, the maximum value of the ordinate O of the equation is calculated. max Given 1.5694, calculate the ordinate O. max The x-coordinate corresponding to 70% is x1 = 5.107, and the y-coordinate is O. max The x-coordinate corresponding to 40% is x2 = 10.213, and the y-coordinate is O. max The x-coordinate corresponding to 10% is x3 = 15.320.

[0060] 4-3), reference Figure 12 Using the center point of a single in-situ regeneration rod as the center, use a marker pen to draw circular marking lines with radii of x1, x2, and x3 respectively, resulting in three circles with radii of x1, x2, and x3. The circular region with radius x1 is marked as region VII, the annular region with radius in the range [x1, x2] is marked as region VIII, and the annular region with radius in the range [x2, x3] is marked as region IX. Region VII is defined as the optimal diffusion region, region VIII as the attenuation region, and region IX as the degradation region. 4-4) Calculate the area S1 of the optimal diffusion zone, the area S2 of the attenuation zone, and the area S3 of the deterioration zone. Define the first diffusion coefficient K1 and the second diffusion coefficient K2 of the composite regenerator. K1 is the ratio of the area S1 of the optimal diffusion zone to the area S2 of the attenuation zone, and K2 is the ratio of the area S1 of the optimal diffusion zone to the area S3 of the deterioration zone. The formula for calculating K1 is: , Wherein, K1 is the first diffusion coefficient of the composite regenerator, S1 is the area of ​​the optimal diffusion region, and S2 is the area of ​​the attenuation region; The formula for calculating K2 is:

[0061] Wherein, K2 is the second diffusion coefficient of the composite regenerator, S1 is the area of ​​the optimal diffusion zone, and S3 is the area of ​​the deterioration zone.

[0062] Specifically, refer to Figure 12 Using the formula for calculating the area of ​​a circle, the optimal diffusion zone area was calculated to be 81.921 cm². 2 The area of ​​the attenuation region is 245.764 cm². 2 The area of ​​the deteriorated zone is 409.606 cm². 2 Then, according to the formula for calculating K1, we get K1=0.33, and according to the formula for calculating K2, we get K2=0.20. The larger K1 and K2 are, the better the regeneration effect of the in-situ regeneration rod.

[0063] In summary, to ensure the feasibility of in-situ recycling of asphalt pavement, a test specimen preparation method and an evaluation method for the test specimen were proposed. The softening point, ductility, rutting factor, creep rate, comprehensive recycling evaluation index, area of ​​the optimal diffusion zone, area of ​​the attenuation zone, and area of ​​the deterioration zone of the recycled asphalt pavement were determined. The analysis showed that the rutting factor and ductility are important indicators for evaluating the recycling effect of in-situ recycling rods, which ensures that the quality and performance of the recycled mixture meet the requirements of road construction.

[0064] The above-described embodiments are merely one implementation of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for in-situ recycling of asphalt pavement, characterized in that, Includes the following steps: S1. Preparation of in-situ regeneration rods; S2. Drill holes in the asphalt pavement and install and fix in-situ recycling rods in the holes; S3. Install temperature sensors in the surface layer of the asphalt pavement, lay wire mesh on the asphalt pavement, and place counterweight bags on the wire mesh. S4. Microwave heating is applied to the area where the wire mesh is laid, followed by heat preservation treatment. Specifically, step S4 involves: The counterweight bags on the surface of the recycled wire mesh are recycled. 300-500ml of water is poured into each hole where the in-situ recycling rod is placed. A microwave heating vehicle is used to heat the road surface in the area where the wire mesh is laid. When the temperature sensor of the asphalt pavement surface structure detects that the road surface temperature reaches above 60℃, the microwave heating vehicle stops. Heat insulation cloth is used to cover and repair the surface. The heat insulation cloth is sealed and fixed with rivets around its perimeter. At the same time, sandbags preheated to 60℃-90℃ are placed at the location where the in-situ recycling rod is laid. The composite recycling agent of the in-situ recycling rod diffuses in a sealed manner. S5. Fill the drilled hole where the in-situ recycling rod is installed. Specifically, after 3-6 hours, remove the heat insulation cloth and sandbags, take out the in-situ recycling rod from the hole, pour the remaining undiffused in-situ recycling rod composite recycling agent into the premixed asphalt mixture, mix it thoroughly and evenly, fill the hole, and then compact the filled area. The asphalt pavement is then microwave-heated again and compacted to complete the in-situ regeneration of the asphalt pavement.

2. The method for in-situ recycling of asphalt pavement according to claim 1, characterized in that, Step S1 includes the following sub-steps: S1-1. Mix the regenerator, diffusion aid, and penetration aid in a ratio of 3:1:1 and place them in a clean container. Use a mixer to stir the mixture evenly to obtain a composite regenerator. S1-2. Pour the composite regenerator into the silicone mold until it overflows, then place the silicone mold containing the composite regenerator in a freezer at -18°C and freeze for 24 hours. S1-3. After freezing and storage, some of the composite regenerant overflows. The overflowing solid composite regenerant is cut off along the opening of the silicone mold to ensure that the upper surface is flat. S1-4. Then, remove the solid composite regenerator from the silicone mold and place it into the metal rod mold. Seal the top surface with a lid to obtain an in-situ regenerated rod. The specific steps of step S2 are as follows: marking the drilling positions on the asphalt pavement, drilling the holes, cleaning the drill cuttings on the inner wall and bottom of the holes, fixing the pre-prepared in-situ regeneration rods in the drilled holes, and evenly spreading activator powder inside the holes.

3. The method for in-situ recycling of asphalt pavement according to claim 2, characterized in that, Step S3 includes the following sub-steps: S3-1. In the area where the in-situ recycling rods are distributed, one temperature sensor is laid out laterally in the center of the lane and one temperature sensor is laid out every 5 meters longitudinally. Circular holes with a diameter of 2-3 cm and a depth of 10 cm are drilled in the surface layer of the asphalt pavement, and the temperature sensors are placed in the circular holes. S3-2. Lay heated wire mesh on the surface of the asphalt pavement, and then fix the ends of the wire mesh.

4. The method for in-situ recycling of asphalt pavement according to claim 3, characterized in that, Step S5 includes the following sub-steps: S5-1. A microwave heating vehicle is used to heat the compacted road surface by traveling. When the temperature sensor of the asphalt pavement surface structure detects that the road surface temperature reaches above 90°C, the microwave heating vehicle stops traveling. S5-2. Compact the asphalt pavement and let it stand for 12-24 hours after compaction.

5. A method for preparing test specimens for in-situ regeneration of asphalt pavement, characterized in that, The sampling of the in-situ regenerated asphalt pavement of claim 1 includes the following steps: (1) Determine the sampling location After the asphalt pavement is recycled in situ, at least one hole that was originally fixed with an in-situ recycling rod is randomly selected. Taking the center point of the single in-situ recycling rod as the center A, circular marking lines with radii of 3dm, 6dm, 9dm, 12dm and 15dm are drawn with a marker pen. The circle with a radius of 15dm is subdivided into 5 arc-shaped areas, which are named Area I, Area II, Area III, Area IV and Area V respectively. These 5 areas are used as sampling locations. (2) Cutting and sampling Five arc-shaped sampling pieces were cut out sequentially from the inside to the outside of regions I, II, III, IV and V using a cutting machine. The cutting depth was the length of the in-situ regeneration rod. (3) Obtain test specimen samples Five arc-shaped sampling pieces were separated by centrifugation to obtain the corresponding asphalt binder, resulting in five arc-shaped test specimen samples.

6. A method for evaluating test specimens of in-situ regeneration of asphalt pavement, characterized in that, The evaluation of the asphalt binder using the five arc-shaped test specimens obtained in claim 5 includes the following steps: 1) Set up a reference group. Without in-situ treatment of the asphalt pavement, cut and centrifuge the asphalt binder of the reference group to obtain a reference sample. 2) Evaluation tests are conducted on the asphalt binder of the test specimen and the asphalt binder of the reference sample. The evaluation tests include softening point test, PG classification test, ductility test and low temperature bending beam rheological test to obtain test data of softening point, ductility, rutting factor and creep rate. The softening point, ductility, rutting factor and creep rate are the evaluation indicators. 3) Plot regression curves based on experimental data, calculate weights, and then define the comprehensive regeneration evaluation index O; 4) Determine the relevant technical parameters of the optimal diffusion zone, the attenuation zone, and the degradation zone to obtain a comprehensive evaluation of the regeneration effect.

7. The method for evaluating test specimens of in-situ regeneration of asphalt pavement according to claim 6, characterized in that, Step 3), which involves plotting a regression curve based on the experimental data, includes the following sub-steps: 3-1) For the softening point test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regeneration rod is used as the abscissa. The ratio D of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample is used. i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, D1), (6, D2), (9, D3), (12, D4), and (15, D5). Based on the data from these 5 coordinate points, we obtain the linear regression equation for the softening point: y=k. 软 x+b 软 D i The calculation formula is: ， Among them, D i The ratio of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample; 3-2) For the ductility test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio M of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference sample is... i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, M1), (6, M2), (9, M3), (12, M4), and (15, M5). Based on the data from these 5 coordinate points, we obtain the linear regression equation y=k. 延 x+b 延 M i The calculation formula is: ， Among them, M i The ratio of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference sample; 3-3) For the PG grading test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio N of the absolute value of the change in rutting factor of the five arc-shaped test specimens to the rutting factor of the reference sample is used. i Using (i=1~5) as the ordinate, we obtain 5 coordinate points (3, N1), (6, N2), (9, N3), (12, N4), and (15, N5). Based on the data from these 5 coordinate points, we obtain the linear regression equation for the rut factor: y=k 车 x+b 车 N i The calculation formula is: ， Where, N i The ratio of the absolute value of the rutting factor change of the five arc-shaped test specimens to the rutting factor of the reference sample; 3-4) For the low-temperature bending beam rheological test, the distance from the radial direction of the arc point of the five arc-shaped test specimens to the center of the in-situ regenerated rod is used as the abscissa. The ratio H of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference sample is... i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, H1), (6, H2), (9, H3), (12, H4), and (15, H5). Based on the data from these 5 coordinate points, we obtain the linear regression equation for the creep rate: y=k 蠕 x+b 蠕 H i The calculation formula is: Among them, H i The value is the ratio of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference specimen.

8. The method for evaluating test specimens of in-situ regeneration of asphalt pavement according to claim 7, characterized in that, Step 3) weight calculation includes the following sub-steps: 3-5) For each regression equation, plot the corresponding straight line L on the same coordinate system. i (i=1~4), draw two perpendicular lines to the X-axis, labeled L. a L b Two perpendicular lines L to the X-axis a L b Passing through points (3, 0) and (15, 0) respectively, L i (i=1~4), L a L b The area of ​​the trapezoid formed by the x-axis and the x-axis is denoted as S. i-a-b-X (i=1~4), S 1-a-b-X S 2-a-b-X S 3-a-b-X and S 4-a-b-X These correspond to softening point, ductility, rutting factor, and creep rate, respectively. 3-6) Calculate the area S of the trapezoid. i-a-b-X (i=1~4), calculate the area S of each trapezoid. i-a-b-X The weights of each evaluation index (i=1~4) are calculated to obtain the weight G. i (i=1~4), G1, G2, G3 and G4 correspond to the softening point evaluation index, ductility evaluation index, rutting factor evaluation index and creep rate evaluation index, respectively. The weight G1 of the softening point index is calculated as follows: ； The formula for calculating the weight G2 of the ductility index is as follows: ； The formula for calculating the weight G3 of the rut factor index is as follows: ； The formula for calculating the weight G4 of the creep rate index is as follows: 。 9. The evaluation method for test specimens of in-situ regeneration of asphalt pavement according to claim 6, characterized in that, Step 3) defines the comprehensive regeneration evaluation index O. i O i (i=1~4) is the sum of the products of the results of the four evaluation indicators and their corresponding weights, representing the comprehensive regeneration evaluation index O. i The calculation formula is: ， Among them, i=1~5, O i D is the comprehensive regeneration evaluation index for areas I-V. i The ratio of the absolute value of the softening point change of the five arc-shaped test specimens to the softening point of the reference sample, M i The ratio of the absolute value of the ductility change of the five arc-shaped test specimens to the ductility of the reference specimen, N i The ratio of the absolute value of the rutting factor change of the five arc-shaped test specimens to the rutting factor of the reference specimen, H i G1 is the ratio of the absolute value of the creep rate change of the five arc-shaped test specimens to the creep rate of the reference sample. G1 is the weight of the softening point index, G2 is the weight of the ductility index, G3 is the weight of the rutting factor index, and G4 is the weight of the creep rate index.

10. The method for evaluating test specimens of in-situ regeneration of asphalt pavement according to claim 6, characterized in that, Step 4) determines the relevant technical parameters of the optimal diffusion region, the attenuation region, and the degradation region, including the following sub-steps: 4-1) Using the radial distance from the arc point of each of the five arc-shaped test specimens to the center of the in-situ regeneration rod as the abscissa, the comprehensive regeneration evaluation index O is calculated. i Using (i=1~5) as the ordinate, we obtain 5 coordinate points: (3, O1), (6, O2), (9, O3), (12, O4), and (15, O5). Based on the data from these 5 coordinate points, we obtain the linear regression equation y=k O x+b O ; 4-2) Based on the regression equation y=k O x+b O Calculate the maximum value O of the ordinate of the equation. max Calculate the maximum value of the ordinate O. max The x-coordinate corresponding to 70% is x1, and the maximum value of the y-coordinate is O. max The x-coordinate corresponding to 40% is x2, and the maximum value of the y-coordinate is O. max The x-coordinate corresponding to 10% is x3; 4-3) Using the center point of a single in-situ regeneration rod as the center, draw circular marking lines with radii of x1, x2, and x3 through the center, respectively, to obtain three circles with radii of x1, x2, and x3. The circular area with radius x1 is marked as region VII, the annular area with radius in the range of [x1, x2] is marked as region VIII, and the annular area with radius in the range of [x2, x3] is marked as region IX. Define region VII as the optimal diffusion region, region VIII as the attenuation region, and region IX as the degradation region. 4-4) Calculate the area S1 of the optimal diffusion zone, the area S2 of the attenuation zone, and the area S3 of the deterioration zone. Define the first diffusion coefficient K1 and the second diffusion coefficient K2 of the composite regenerator. K1 is the ratio of the area S1 of the optimal diffusion zone to the area S2 of the attenuation zone, and K2 is the ratio of the area S1 of the optimal diffusion zone to the area S3 of the deterioration zone. The formula for calculating K1 is: ， Wherein, K1 is the first diffusion coefficient of the composite regenerator, S1 is the area of ​​the optimal diffusion region, and S2 is the area of ​​the attenuation region; The formula for calculating K2 is: Wherein, K2 is the second diffusion coefficient of the composite regenerator, S1 is the area of ​​the optimal diffusion zone, and S3 is the area of ​​the deterioration zone.

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