Full-depth foamed asphalt cold recycling construction method

Abstract

The application provides a full-depth foamed asphalt cold regeneration construction method, comprising the following steps: S1, determining mechanical configuration; S2, determining regeneration material mix proportion design; S3, test section construction; and S4, foamed asphalt in-situ cold regeneration construction; in the application, the milling cutter two is far away from the milling cutter one, so that the working depth of the adjusted milling cutter two and the milling cutter two is ensured to be different, and the need of deep pavement milling is met; the adjustable screening mechanism arranged in the application can adjust the size of the screen hole according to the need, so that the need of different sizes during sampling is met, and the convenience during use is improved; the application relates to the technical field of road engineering, in particular to a full-depth foamed asphalt cold regeneration construction method; the application is developed in view of the shortage of the prior art, and a full-depth foamed asphalt cold regeneration construction method is provided, and the application facilitates asphalt pavement repair.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to a full-depth foamed asphalt cold recycling construction method. Background Technology

[0002] With my country's rapid economic development and high-speed growth in traffic volume, the phenomena of heavy-load and overloaded vehicles have become increasingly serious, and various defects in traditional asphalt pavements have become more and more apparent. As of 2017, the total length of highways in China reached 4.6963 million kilometers, including 131,000 kilometers of expressways. The length of highways under maintenance reached 4.59 million kilometers, accounting for 97.7% of the total highway mileage. my country's highway transportation spends a considerable amount on highway maintenance. The rational utilization of asphalt pavement waste can reduce environmental pollution and the phenomenon of waste accumulation occupying land, and is more conducive to the protection of my country's natural resources.

[0003] At present, asphalt pavement recycling technology can be divided into hot mix and cold mix based on the mixing temperature of the mixture, on-site mixing and road mixing based on the mixing location, and in-situ cold recycling of asphalt layers and full-depth in-situ cold recycling based on the recycled materials and thickness.

[0004] In full-depth in-situ cold recycling construction, when designing the mix proportion, only about 1 to 3 sets of samples that meet the specifications are selected for Marshall tests to select the dominant mix proportion. No optimal mix proportion design scheme for foamed asphalt cold recycling is proposed.

[0005] Therefore, in order to address the above problems, a full-depth foamed asphalt cold recycling construction method is proposed to solve these problems. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by developing a full-depth foamed asphalt cold recycling construction method, which facilitates the repair of asphalt pavements.

[0007] The technical solution to the problem solved by this invention is as follows: This invention provides a full-depth foamed asphalt cold recycling construction method, comprising the following steps: S1: Determine the mechanical configuration; S2: Determine the mix design of recycled materials; S3: Construction of the test section; S4: In-situ cold recycling of foamed asphalt.

[0008] The mechanical configuration in S1 includes a recycling machine, a cement spreader, a tanker truck, a paver, a compaction equipment, a material transport vehicle, and a loader. The specific structure of the recycling machine includes an outer shell, a motor, wheels, a mounting cavity, a layered milling mechanism, an adjustable screening mechanism, and a sampling and conveying mechanism. The motor is fixedly connected to the lower left and right sides of the outer shell, and wheels are fixedly connected to the external output shaft of the motor. The mounting cavity is located inside the lower side of the outer shell. The layered milling mechanism is located on the left side of the mounting cavity. The adjustable screening mechanism is located on the right side of the mounting cavity. The sampling and conveying mechanism is located inside the right side of the outer shell.

[0009] As an optimization, the specific structure of the layered milling mechanism includes a hydraulic cylinder, a movable seat, a motor, a connecting shaft, a drive pulley, a belt, a milling hob, a connecting shaft, a transmission pulley, a belt, a transmission pulley, a connecting shaft, a milling hob, a conveying pipe, a screw rod, and a motor. The motor is fixedly connected to the outer left front side of the outer casing. The connecting shaft is movably connected to the lower left side of the mounting cavity, and the center of the front side of the connecting shaft is fixedly connected to the output shaft of the motor. The drive pulley is located behind the movable seat, and its center is fixedly connected to the outer rear side of the connecting shaft. The left side of the movable seat is movably connected to the outer side of the connecting shaft. The lower left side of the movable seat is movably connected to the connecting shaft, and the connecting shaft is fixedly connected to the outer rear side of the connecting shaft. There is a transmission pulley 1, which is connected to the drive pulley via a belt 1. A connecting shaft 3 is movably connected to the lower right side inside the movable seat, and a transmission pulley 2 is fixedly connected to the outer rear side of the connecting shaft 3. The transmission pulley 2 is connected to the transmission pulley 1 via a belt 2. The upper side of the hydraulic cylinder 1 is movably connected to the upper left side of the mounting cavity, and the lower piston rod of the hydraulic cylinder is movably connected to the upper left side of the movable seat. The milling hob 1 is fixedly connected to the outside of the connecting shaft 1. The milling hob 2 is fixedly connected to the outside of the connecting shaft 3. The conveying pipe is fixedly connected to the upper right side inside the movable seat, and a motor 3 is fixedly connected to the top of the conveying pipe. The screw rod 1 is movably connected to the inside of the conveying pipe, and the upper center of the screw rod 1 is fixedly connected to the output shaft of the motor 3.

[0010] As an optimization, the adjustable screening mechanism includes a fixed base, a guide groove, a screening chamber, a sieve hole seat, a sieve hole cavity, an adjusting sieve plate, a screw, a motor, a turntable, a fixed shaft, a sliding block, a motor, a driven gear, a driving gear, and a splined shaft. The fixed base has a screening chamber inside its left side, with a guide groove in the center of the screening chamber. Motor 4 is fixedly connected to the upper right side of the fixed base. The sieve hole seat is laterally movably connected inside the guide groove, with a sliding block fixedly connected to the right end of the sieve hole seat. A sieve hole cavity is located inside the center of the sieve hole seat. The screw is movably connected to the center right side of the sieve hole cavity, with a driven gear fixedly connected to the right end of the screw. The adjusting sieve plate is externally... The adjusting screen plate is laterally movably connected inside the screen cavity. A threaded hole in the center of the right side of the adjusting screen plate is connected to a screw rod. The turntable is movably connected inside the upper right side of the fixed base. The center of the turntable is fixedly connected to the lower output shaft of the motor. A fixed shaft is fixedly connected to the lower edge of the turntable, and the outside of the fixed shaft is movably connected to the interior of the longitudinal groove on the upper side of the sliding block. The motor is fixedly connected to the lower right side of the fixed base. A spline shaft is fixedly connected to the left output shaft of the motor. The driving gear is movably connected inside the lower right side of the screen cavity. A spline hole in the center of the driving gear is connected to a spline shaft. The upper teeth of the driving gear are connected to the lower teeth of the driven gear.

[0011] As an optimization, the specific structure of the sampling and conveying mechanism includes a collection trough seat, a second screw rod, a collection trough, a conveying hole, a connecting block, a second hydraulic cylinder, a chute, a lifting and conveying channel, a third screw rod, a collection box, a sixth motor, and a seventh motor; the chute is horizontally opened on the lower right side of the mounting cavity, and a horizontally connected collection trough seat is movably connected inside the chute; a collection trough is provided on the left side of the collection trough seat, a conveying hole is provided on the lower side of the collection trough seat, a seventh motor is fixedly connected to the external right side of the collection trough seat, and a connecting block is fixedly connected to the bottom of the collection trough seat; the second screw rod is movably connected to the conveying hole. Inside the feeding hole, the center of the right side of the second spiral rod is fixedly connected to the output shaft of the left side of the seventh motor; the second hydraulic cylinder is fixedly connected to the lower right side of the slide groove, and the end of the left piston rod of the second hydraulic cylinder is fixedly connected to the right side of the connecting block; the collection box is located inside the right side of the outer shell; the lifting and conveying channel is located inside the right side of the outer shell, and the upper right outlet of the lifting and conveying channel is connected to the inside of the collection box; the sixth motor is fixedly connected to the upper right side of the outer shell; the third spiral rod is movably connected inside the lifting and conveying channel, and the center of the upper side of the third spiral rod is fixedly connected to the lower output shaft of the sixth motor.

[0012] As an optimization, the specific steps of S3 are as follows: S31: Construction preparation; S311: The minimum daily temperature during the construction period of foamed asphalt in-situ cold recycling structural layer should be above 10°C; S312: Select the test section as required; S32: Construction plan finalized: S321: Based on experience and the characteristics of the recycling machinery used, formulate 3 to 5 different combinations of recycling machine travel speed and rotor speed. Mill the old road according to the designed recycling depth. Take representative materials after milling and send them to the laboratory for screening. Select the scheme with the gradation closest to the ideal gradation as the scheme of recycling machine travel speed and rotor speed during construction. S322: Based on the determined regenerator travel speed and rotor speed, take representative material samples after milling and send them to the laboratory for indoor mix design verification; S323: Use 1 to 3 compaction schemes for construction (including roller tonnage, rolling sequence, number of passes, etc.) to determine the most reasonable compaction scheme. S324: Select representative recycled mixtures and send them to the laboratory to determine the moisture content and maximum dry density of the recycled mixtures. Then, mold specimens and determine their wet and dry splitting strength to verify the production mix proportion. S325: Test the deflection, compaction, flatness, thickness, width and other indicators of the test section; S326: Based on the results of the test section, the final determination of the gradation of the recycled mixture, the traveling speed of the recycling machine, the rotor speed, and the compaction process of the recycled mixture during construction.

[0013] As an optimization, the specific steps of S2 are as follows: S21: Inspection of original road surface materials; Before applying foamed asphalt in-situ cold recycling, it is necessary to sample the original pavement material. If possible, a recycling machine can be used to mill representative samples from the existing pavement. Sampling with a recycling machine not only provides a useful visual understanding of the structural layers and pavement materials but also offers the opportunity to extract real samples for laboratory testing. These samples allow for the evaluation of the material quality of the original pavement structural layers and accurately reflect the mix design results. If this is not possible, a milling machine can be used at an appropriate speed (a milling speed of 3–4 m / min is generally recommended).

[0014] S211: The selected milling material samples shall be tested in strict accordance with relevant specifications and procedures; S212: For poorly graded milled waste material, its gradation should be improved by adding some new material. For newly added material, representative samples from the designated material yard should be taken and tested strictly in accordance with relevant specifications and procedures.

[0015] S22: Material requirements; S221: The materials to be stabilized in in-situ cold recycling of foamed bitumen shall meet the following requirements: The maximum particle size of a single particle in a foamed asphalt stabilized recycled layer should not exceed 37.5 mm; S222: The minimum acceptable expansion rate and half-life of the base asphalt used for foaming are 10 times and 8 seconds, respectively. Asphalt that does not meet these requirements should be replaced. If the foaming requirements can be met by adding a foaming agent without affecting the properties of the asphalt itself, it can also be used.

[0016] S223: When cement is used as a recycled active filler, ordinary Portland cement, slag Portland cement, and pozzolanic Portland cement may be used. Cement with an initial setting time of 3 hours or more and a final setting time of 6 hours or more should not be used. Rapid-hardening cement, high-early-strength cement, or cement that has been damp and deteriorated should not be used. Cement should be loose, dry, and free of lumps and caking. For composite Portland cement, its strength must be tested beforehand. The cement strength grade is usually 42.5 MPa.

[0017] S224: Clean water should be used for foamed asphalt stabilization recycling. Testing should be conducted if there is any doubt about the water quality.

[0018] S23: Asphalt performance testing; S231: When designing the mix proportions, the basic indicators and foaming properties of the base asphalt must first be tested; S232: After the basic indicators of the asphalt are tested, the foaming characteristics can be determined, as follows: S2321: The foaming temperature of asphalt is usually selected from three temperatures: 150°C, 160°C, and 170°C. S2322: The foaming water content shall be at least 4 units, typically 1.5%, 2.0%, 2.5%, and 3.0% of the asphalt mass. S2323: Heat the asphalt circulating in the testing machine to the required temperature and maintain it for at least 5 minutes before starting the test; S2324: Calibrate the asphalt injection flow rate and set a timer so that the amount of asphalt injected each time is 500g; S2325: Spray foamed asphalt into a steel drum (275mm in diameter), and use the scale provided with the testing machine to measure the maximum height of the foamed asphalt inside the drum as the maximum volume; S2326: The time taken for foamed bitumen to decay to half its maximum volume is measured using a stopwatch and is taken as the half-life of the foamed bitumen. S2327: Repeat at least three times until the readings of maximum volume and half-life are similar each time; S2328: For each temperature, repeat S2325~S2327 at at least 3 moisture contents; S2329: Plot a graph with water content (%) on the x-axis and expansion rate (multiple) and half-life (S) on the y-axis, based on experimental data, and select the foaming temperature and foaming water volume that can produce the best foaming effect.

[0019] S24: Mineral aggregate gradation design S241: The gradation of each component material in the recycled asphalt pavement material and the new aggregate was measured; S242: Determine the composite gradation based on the gradation of the old mixture and the new additive. The gradation range is shown in Table 1. Plot the gradation curve to ensure that the designed composite gradation is within the corresponding gradation range. The designed composite gradation should be close to the median value of the gradation range in the table. If repeated adjustments are not satisfactory, the new additive should be replaced and the design should be repeated.

[0020] S25: Determination of maximum dry density and optimum moisture content; S251: When stabilizing old pavement materials with foamed asphalt, a small amount of cement or lime is usually added in combination with the foamed asphalt. Cement is commonly used in construction. When preparing test samples, the cement dosage is usually 1.5%. The cement dosage is expressed as a percentage of the cement mass to the total dry mass of the material, i.e., cement dosage = cement mass / (cement mass + dry mass of the old material to be stabilized).

[0021] S252: Determine the maximum dry density and optimum moisture content of the mixture according to the method in T0131 of the "Specifications for Testing Geotechnical Engineering for Highways" (JTG-E40).

[0022] S26: Sample preparation; S261: Calculate the dry mass of the recycled mixture sample; S262: Calculate the amount of active filler required; S263: Place the required quantity of mixture and filler into the mixing tank and dry mix for 30 seconds; S264: Calculate and determine the optimal amount of water for mixing; S265: Add water to the mixing tank and mix for 30 seconds until homogeneous; S266: Determine the amount of foamed asphalt (the amount of asphalt is generally selected as 1.5%, 2%, 2.5%, or 3%), and consider the influence of some asphalt adhering to the mixing blades of the mixing pot. The actual amount of asphalt added is usually 1.25 times the calculated value. S267: Connect the mechanical mixing plant and the foaming equipment together so that foamed asphalt can be directly sprayed into the mixing pot; S268: Turn on the mixer and mix for at least 10 seconds before spraying foamed asphalt into the mixing pot, and continue mixing for 30 seconds after spraying foamed asphalt. S269: Transfer the mixed foamed asphalt stabilized material into a container and seal it immediately to prevent moisture loss; S2610: Produce specimens immediately following the steps below, with at least 4 different foamed bitumen contents.

[0023] S27: Molded test specimen S271: Mix the various parts according to the proportion of old asphalt pavement milling material and cement in the synthetic gradation, add water corresponding to 65% of the optimum moisture content determined by the heavy compaction test to the mixture, and then add 1.5%, 2.0%, 2.5% and 3.0% of the four types of foamed asphalt respectively and mix. S272: For medium-grained gradation, the mixed material is compacted on both sides 75 times each using the Marshall compaction method to form specimens; S273: Place the sample and mold together on their side in a 60°C forced-air oven to cure until constant weight. The curing time is generally not less than 40 hours. S274: Remove the mold from the oven and place the sample directly on its side to cool for 12 hours before demolding; S28: Determine the optimal amount of foamed bitumen; S281: Each group of foamed asphalt specimens shall undergo a 15°C splitting tensile test and a 24-hour water immersion splitting tensile test. The 24-hour water immersion splitting tensile test method is as follows: the specimen is completely immersed in a 25°C constant temperature water bath for 22 hours, then completely immersed in a 15°C constant temperature water bath for 2 hours, and then immediately subjected to a 15°C splitting tensile test. The splitting tensile strength test shall be conducted according to the method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011).

[0024] S282: Based on the results of splitting strength and immersion splitting strength tests, combined with Table 2.7 and engineering experience, the optimal foamed asphalt content (OAC) is determined comprehensively.

[0025] S283: For roads with high-volume, extra-heavy, or extremely heavy traffic, if foamed asphalt mixtures are used in the surface layer structure, triaxial tests are required to determine the shear strength of the foamed asphalt mixture, thereby improving the long-term performance of the road. Vibrated cylindrical specimens should have a diameter of φ-150mm and a height of h-300mm. If the performance indicators of recycled mixtures do not meet the design requirements, the mix design should be revised by adjusting the material composition.

[0026] As an optimization, in step S2, the recycled materials include recycled asphalt mixture and cement, with a mineral aggregate ratio of 98.2:1.8, an asphalt foaming temperature of 160±5℃, a water content of 2.4%, a foamed asphalt content of 3.0%, an optimum moisture content of 4.8%, and a maximum dry density of 2.06 g / m³. 3 .

[0027] As an optimization, the specific steps of S4 are as follows: S41: Construction layout; Before reconstruction, a series of marker stakes (poles) should be placed on both sides of the road as baselines to restore the road's centerline. The spacing between the marker stakes (poles) should not exceed 20 meters for curves and 40 meters for straight sections.

[0028] S42: Original road surface treatment; Remove debris from the original road surface (including adjacent lanes and shoulders that do not require regeneration) and mark the edge lines. Remove manhole covers and similar structures from the regenerated section. Treat defects such as frost heave, ruts, subsidence, undulations, and potholes on the original road to make it basically smooth.

[0029] S43: Pre-reshaping of the original road; When the cross slope (including superelevation or camber) and longitudinal slope of the original road need to be adjusted, certain methods should be used to smooth out the original unevenness such as local bulges or depressions to meet the design requirements.

[0030] Large settlements or slope changes exceeding the thickness of the recycled layer must be treated separately before recycling.

[0031] For road sections with particularly high groundwater levels, drainage ditches (or blind drains) should be excavated at regular intervals (10-30m) on both sides of the road shoulders of the regenerated road section.

[0032] S44: Prepare newly added materials; S441: Under normal circumstances, no new materials need to be added, unless the gradation of the original pavement material is very undesirable; S442: The thickness of the added virgin material must be less than the thickness of the recycled material, and usually not exceed 5 cm. S443: Calculate the amount of newly added material: Calculate the amount of new material to be added per square meter based on the average density within the original road recycling depth; The newly added material is spread using a paver; When a paver is unavailable, a grader or loader can be used as an auxiliary tool. In this case, the cost should be calculated based on the weight or volume of each truckload of material. Calculate the stacking distance for each truckload of material, and ensure that the quantity of material in each truckload is approximately equal; S444: Within the same material yard supply route, spread or level the material from far to near to avoid insufficient or excessive material in some sections; S445: Spread the new material evenly on the old road surface, at a rate of 1000m. 2 This is a uniform section; check whether the quality of the newly added material is uniform.

[0033] S45: Cement spreading; Cement should be added using cement slurry trucks or cement spreader trucks.

[0034] Do not spread cement on the entire construction section at the same time. Instead, spread cement evenly within the working width of the cold recycling machine. Only after completing one working width of the work area should you spread cement on the next working area.

[0035] S46: Cold recycling machine milling and mixing; Arrange the construction equipment as follows: cement spreader truck - water tanker truck - hot asphalt tanker truck - recycling machine - paver - roller, and connect the corresponding pipelines. Start the construction equipment and mill and mix the road surface according to the set recycling depth. When the recycling machine starts working, the rotor should be completely cut down to the bottom of the recycled layer to break up the recycled material, so that the mixed depth of the loosened recycled material meets the design requirements. The working width of the recycling machine is 3.8 meters, and recycling requires three operations depending on the road width.

[0036] The travel speed of the cold recycling machine should be adjusted according to the road surface damage and recycling depth, generally between 4m / min and 5m / min, to minimize fluctuations in the gradation of the milled material. In areas with severe network cracking, the recycling machine's travel speed should be reduced, and the rotor speed increased. A dedicated person should follow the recycling machine to continuously check the recycling depth and assist the operator in making adjustments. For recycling machines with screeds, the thickness of the mixture behind the screed should be checked frequently. After each recycling stage, the milling hub's cutter holder and cutter head should be inspected, and any damaged parts replaced immediately.

[0037] S47: Recycled material paving; Paving operations must be carried out slowly, evenly, and continuously; the paving speed must not be changed arbitrarily or the process must not be stopped midway. Paving cannot be carried out on rainy days, and paving should also be stopped if the temperature is below 10℃.

[0038] The loose paving coefficient of foamed asphalt recycled layer is generally 1.4~1.45.

[0039] S48: Recycled material compaction; S481: Based on the different road widths, roller wheel widths, and wheel gauges, a compaction plan should be formulated to ensure that each part is compacted as many times as possible, and the sides of the road surface should be compacted 2-3 more times.

[0040] S482: A single-drum vibratory roller should be installed after the recycling machine for initial compaction. During initial compaction, the roller should first perform one pass of static compaction, closely following the recycling machine. After static compaction, high-amplitude, low-frequency vibration compaction should be used. The number of compaction passes should be sufficient to ensure that the compaction degree within the bottom 2 / 3 thickness of the recycled layer meets the specified requirements. Each compaction cycle should begin at the start of the construction section and end at the edge of the recycling machine, with the compaction width exceeding the width of the recycling section. The operating speed of the roller must not exceed 3 km / h.

[0041] S483: If wheel sticking occurs during initial compaction with a large-tonnage single-drum roller, the rubber-tired roller can be pre-sprayed with water for pre-compaction before initial compaction.

[0042] S484: After the initial compaction, a double-drum vibratory roller is used for secondary compaction with weak vibration (low amplitude, high frequency). On straight sections and horizontal curves without superelevation, when rolling from the shoulder towards the center of the road, the roller should overlap by 1 / 2 the roller width, completing one pass when the full width of the road surface is covered. Generally, 4-6 passes are required. The roller speed should be 1.5-1.7 km / h for the first two passes, and 2.0-2.5 km / h thereafter.

[0043] S485: Finally, use a rubber-tired roller for final compaction, at least 8 passes. Water can be sprayed for compaction if necessary.

[0044] S486: It is strictly forbidden for road rollers to turn around or brake suddenly on completed or ongoing road sections, and the surface of the recycled layer must be protected from damage.

[0045] S487: During the compaction process, the surface of the recycled layer should always be kept moist. If the moisture evaporates too quickly, a small amount of water should be added in time, but it is strictly forbidden to spray a large amount of water for compaction.

[0046] S49: Treatment of transverse and longitudinal seams S491: Treatment of transverse seams: A. Downtime should be minimized during construction. B. The machinery should be strictly inspected, especially the air venting of the water pipes. Gas must be removed before the liquid reaches the spray bar. C. Pay attention to checking the amount of cement slurry or water sprayed in order to avoid excessive or insufficient application in the horizontal direction. D. When the recycling machine resumes operation at the shutdown location, the entire recycling machine must be moved back to a distance of 1.5m from the recycled material. S492: Treatment of Longitudinal Joints: The working width of the recycling machine is 3.8 meters. Recycling requires three operations depending on the road width, resulting in longitudinal joints between two adjacent work surfaces. The minimum overlap between adjacent work surfaces is 10 cm to ensure the continuity of recycled material at the longitudinal joint and to avoid unrecycled material being trapped between adjacent work surfaces. The longitudinal joint should be kept moist to facilitate bonding between materials. The location of the longitudinal joint should avoid the wheel tracks of slow-moving and heavy vehicles as much as possible.

[0047] S410: Health preservation.

[0048] After the foamed asphalt recycled base course is completed, the curing time before the upper structural layer is laid should not be less than 7 days, or the moisture content should be less than 2%.

[0049] When maintaining health in a closed-off environment, one can engage in natural health practices and generally does not need to take other measures.

[0050] When conducting health maintenance under open traffic conditions, the passage of heavy vehicles should be strictly restricted, the driving speed should be controlled within 20km / h, and vehicles are strictly prohibited from making U-turns or speeding on the regeneration layer.

[0051] To prevent damage to the surface layer from vehicle wheels, slow-cracking emulsified asphalt can be evenly spread on the recycled layer for maintenance.

[0052] The effects described in the invention are merely those of the embodiments, and not all the effects of the invention. The above technical solutions have the following advantages or beneficial effects: 1. This invention optimizes the mix proportions of foamed asphalt cold recycled mixtures, improving the interlocking ability of aggregates and enhancing the shear stress resistance of the mixture, effectively supplementing the current Marshall method specification. It clearly specifies the proportions of recycled materials and the recycling conditions. The recycled materials include recycled asphalt mixture and cement, with an aggregate ratio of 98.2:1.8, an asphalt foaming temperature of 160±5℃, a water content of 2.4%, a foamed asphalt content of 3.0%, an optimum moisture content of 4.8%, and a maximum dry density of 2.06 g / m³. 3 It can effectively utilize old road materials and improve road surface performance.

[0053] 2. This invention optimizes the layout of the recycling train sets, arranging the construction equipment in the order of cement spreader truck - water tanker truck - hot asphalt tanker truck - recycling machine - paver - roller. This overcomes the problems of dust and uneven mixing when adding aggregates, making the recycling train sets more suitable for the domestic construction market. It effectively overcomes problems such as environmental pollution, deviation of aggregate addition from the mix ratio, and uneven aggregate mixing, improves construction quality, expands the applicable scope of foamed asphalt cold recycling construction, and contributes to the promotion of foamed asphalt in-situ cold recycling technology.

[0054] 3. In this invention, since the second milling cutter is far away from the first milling cutter, it ensures that the working depths of the second milling cutter and the first milling cutter are different after adjustment, thus meeting the needs of milling deeper road surfaces.

[0055] 4. The adjustable screening mechanism provided in this invention can adjust the size of the sieve holes as needed, thereby meeting the needs of different sizes during sampling and improving the convenience of use.

[0056] 5. The sampling and conveying mechanism provided in this invention can extend the collection trough seat by extending the cylinder two, thereby facilitating the conveying of the screened material to the lower side of the lifting and conveying channel by the rotating screw rod two. Then, the motor six drives the screw rod three to rotate, and the rotation of the screw rod three conveys the material to the collection box, which makes it easier to send the sample material to the laboratory for testing, thereby improving the convenience of use. Attached Figure Description

[0057] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0058] Figure 1 This is a gradation curve diagram of the present invention.

[0059] Figure 2 This is a schematic diagram of the splitting strength of the present invention.

[0060] Figure 3 This is a schematic diagram of the dry and wet splitting strength ratio of the present invention.

[0061] Figure 4 This is a schematic diagram of the regeneration machine.

[0062] Figure 5 for Figure 4 A sectional view.

[0063] Figure 6 This is a schematic diagram of the layered milling mechanism.

[0064] Figure 7 This is a schematic diagram of the adjustable screening mechanism.

[0065] Figure 8 This is a schematic diagram of the sampling and conveying mechanism.

[0066] 1-Outer shell; 2-Motor 1; 3-Wheel; 4-Mounting cavity; 5-Layer milling mechanism; 6-Adjustable screening mechanism; 7-Sampling and conveying mechanism; 51-Cylinder 1; 52-Moving seat; 53-Motor 2; 54-Connecting shaft 1; 55-Drive pulley; 56-Belt 1; 57-Milling hob 1; 58-Connecting shaft 2; 59-Transmission pulley 1; 510-Belt 2; 511-Transmission pulley 2; 512-Connecting shaft 3; 513-Milling hob 2; 514-Conveying pipe; 515-Screw rod 1; 516-Motor 3; 61-Fixed seat; 62- 63-Guide trough; 64-Screw hole seat; 65-Screw hole cavity; 66-Adjusting screen plate; 67-Screw one; 68-Motor four; 69-Turntable; 610-Fixed shaft; 611-Slide block; 612-Motor five; 613-Driven gear; 614-Drive gear; 615-Splined shaft; 71-Collection trough seat; 72-Screw rod two; 73-Collection trough; 74-Conveying hole; 75-Connecting block; 76-Hydraulic cylinder two; 77-Slide trough; 78-Lifting and conveying channel; 79-Screw rod three; 710-Collection box; 711-Motor six; 712-Motor seven. Detailed Implementation

[0067] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings. The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure of the invention, components and arrangements of specific examples are described below. Furthermore, reference numerals and / or letters may be repeated in different examples. This repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. It should be noted that the components illustrated in the drawings are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and processes are omitted to avoid unnecessarily limiting the invention. Terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0068] like Figures 1 to 8 As shown, a full-depth foamed asphalt cold recycling construction method includes the following steps: S1: Determine the mechanical configuration.

[0069] like Figure 4 and Figure 5 As shown, the mechanical configuration in S1 includes a recycling machine, a cement spreader, a tanker truck, a paver, a compaction device, a material transport vehicle, and a loader. The specific structure of the recycling machine includes a housing 1, a motor 2, wheels 3, a mounting cavity 4, a layered milling mechanism 5, an adjustable screening mechanism 6, and a sampling and conveying mechanism 7. The motor 2 is fixedly connected to the interior of the lower left and right sides of the housing 1, and wheels 3 are fixedly connected to the external output shaft of the motor 2. The mounting cavity 4 is provided inside the lower side of the housing 1. The layered milling mechanism 5 is located on the left side of the mounting cavity 4. The adjustable screening mechanism 6 is located on the right side of the mounting cavity 4. The sampling and conveying mechanism 7 is located inside the right side of the housing 1.

[0070] like Figure 6As shown, the specific structure of the layered milling mechanism 5 includes a hydraulic cylinder 51, a movable seat 52, a motor 53, a connecting shaft 54, a drive pulley 55, a belt 56, a milling hob 57, a connecting shaft 58, a transmission pulley 59, a belt 510, a transmission pulley 511, a connecting shaft 512, a milling hob 513, a conveying pipe 514, a screw rod 515, and a motor 516; the motor 53 is fixedly connected to the outside of the left front side of the outer casing 1. The connecting shaft 54 ​​is movably connected to the lower left side of the mounting cavity 4, and the center of the front side of the connecting shaft 54 ​​is fixedly connected to the output shaft of the motor 53. The drive pulley 55 is located behind the movable seat 52, and the center of the drive pulley 55 is fixedly connected to the outside of the rear side of the connecting shaft 54. The left side of the movable seat 52 is movably connected to the outside of the connecting shaft 54. The lower left side of the movable seat 52 is movably connected to the connecting shaft 58, and the outer rear side of the connecting shaft 58 is fixedly connected to the transmission pulley 59. The transmission pulley 59 is connected to the drive pulley 55 through the belt 56. The lower right side of the movable seat 52 is movably connected to the connecting shaft 512, and the outer rear side of the connecting shaft 512 is fixedly connected to the transmission pulley 511. The transmission pulley 511 is connected to the transmission pulley 59 through the belt 510. The upper side of the cylinder 51 is movably connected to the upper left side of the mounting cavity 4, and the lower piston rod of the cylinder 51 is connected to the upper left side of the movable seat 52. The milling hob 57 is internally fixedly connected to the outside of the connecting shaft 54; the milling hob 513 is internally fixedly connected to the outside of the connecting shaft 512; the conveying tube 514 is fixedly connected to the upper right side inside the movable seat 52, and the top of the conveying tube 514 is fixedly connected to the motor 516; the screw rod 515 is movably connected to the inside of the conveying tube 514, and the upper center of the screw rod 515 is fixedly connected to the output shaft of the motor 516.

[0071] like Figure 7As shown, the adjustable screening mechanism 6 includes a fixed base 61, a guide groove 62, a screening chamber 63, a sieve hole seat 64, a sieve hole cavity 65, an adjusting sieve plate 66, a screw 67, a motor 68, a turntable 69, a fixed shaft 610, a sliding block 611, a motor 612, a driven gear 613, a driving gear 614, and a splined shaft 615. The fixed base 61 has a screening chamber 63 inside its left side, and a guide groove 62 in the center of the screening chamber 63. A motor 68 is fixedly connected to the upper right side of the fixed base 61. The sieve hole seat 64 is laterally movably connected inside the guide groove 62. A sliding block 611 is fixedly connected to the right end of the sieve hole seat 64, and a sieve hole cavity 65 is located inside the center of the sieve hole seat 64. The screw 67 is movably connected to the center right side of the sieve hole cavity 65, and a driven gear 613 is fixedly connected to the right end of the screw 67. The adjusting screen plate 66 is laterally movably connected to the inside of the screen cavity 65. The threaded hole at the center of the right side of the adjusting screen plate 66 is connected to the screw 67. The turntable 69 is movably connected to the inside of the upper right side of the fixed base 61. The center of the turntable 69 is fixedly connected to the lower output shaft of the motor 68. A fixed shaft 610 is fixedly connected to the lower edge of the turntable 69, and the outside of the fixed shaft 610 is movably connected to the inside of the longitudinal groove on the upper side of the sliding block 611. The motor 612 is fixedly connected to the lower right side of the fixed base 61. A spline shaft 615 is fixedly connected to the left output shaft of the motor 612. The driving gear 614 is movably connected to the inside of the lower right side of the screen cavity seat 64. The spline hole at the center of the driving gear 614 is connected to the spline shaft 615. The upper teeth of the driving gear 614 are connected to the lower teeth of the driven gear 613.

[0072] like Figure 8As shown, the specific structure of the sampling and conveying mechanism 7 includes a collection trough seat 71, a second spiral rod 72, a collection trough 73, a conveying hole 74, a connecting block 75, a second hydraulic cylinder 76, a slide 77, a lifting and conveying channel 78, a third spiral rod 79, a collection box 710, a sixth motor 711, and a seventh motor 712; the slide 77 is horizontally opened on the lower right side of the mounting cavity 4, and the horizontal collection trough seat 71 is movably connected inside the slide trough 77; the collection trough seat 71 has a collection trough 73 on its left side, a conveying hole 74 on its lower side, a seventh motor 712 fixedly connected to the outside of the right side of the collection trough seat 71, and a connecting block 75 fixedly connected to the bottom of the collection trough seat 71; the second spiral rod 72... The spiral rod 72 is movably connected inside the conveying hole 74. The center of the right side of the spiral rod 72 is fixedly connected to the output shaft of the motor 712 on the left side. The hydraulic cylinder 76 is fixedly connected to the lower right side of the slide groove 77. The end of the piston rod on the left side of the hydraulic cylinder 76 is fixedly connected to the right side of the connecting block 75. The collection box 710 is located inside the right side of the outer shell 1. The lifting conveying channel 78 is located inside the right side of the outer shell 1. The upper right outlet of the lifting conveying channel 78 is connected to the inside of the collection box 710. The motor 711 is fixedly connected to the upper right side of the outer shell 1. The spiral rod 79 is movably connected inside the lifting conveying channel 78. The center of the upper side of the spiral rod 79 is fixedly connected to the output shaft of the lower side of the motor 711.

[0073] The recycling machine operates as follows: First, the extension of cylinder 51 causes the movable seat 52 to rotate around connecting shaft 54, thereby adjusting the working depth of milling cutter 57 and milling cutter 513. Since milling cutter 513 is located away from milling cutter 57, the adjusted working depths of milling cutter 513 and milling cutter 513 are different, thus meeting the needs of milling deeper surfaces. Then, motor 53 is started to drive milling cutter 513 and milling cutter 513 to rotate together, thus conveying the milled material to the lower inlet of conveying pipe 514. Then, motor 516 drives the auger 515 to rotate, while auger 51... The rotation of 5 transports the material to the adjustable screening mechanism 6 for screening. The adjustable screening mechanism 6 can adjust the size of the sieve holes as needed to meet the needs of different sizes during sampling, thus improving the convenience of use. The sampling and conveying mechanism 7 can extend the collection trough seat 71 by extending the cylinder 2 76, so that the screened material can be transported to the lower side of the lifting and conveying channel 78 by the rotating screw rod 2 72. Then, the motor 6 711 drives the screw rod 3 79 to rotate, and the rotation of the screw rod 3 79 transports the material to the collection box 710, which makes it easier to send the sample material to the laboratory for testing, thus improving the convenience of use.

[0074] S2: Determine the mix design of recycled materials.

[0075] The specific steps of S2 are as follows: S21: Inspection of original road surface materials; Before applying foamed asphalt in-situ cold recycling, it is necessary to sample the original pavement material. If available, a recycling machine can be used to mill representative samples from the existing pavement. Sampling with a recycling machine not only provides a useful visual understanding of the structural layers and pavement materials but also offers the opportunity to extract real samples for laboratory testing. These samples allow for the evaluation of the material quality of the original pavement structural layers and accurately reflect the mix design results. If this is not possible, a milling machine can be used at an appropriate speed (a milling speed of 3–4 m / min is generally recommended).

[0076] S211: The selected milling material samples shall be tested in strict accordance with relevant specifications and procedures; S212: For poorly graded milled waste material, its gradation should be improved by adding some new material. For newly added material, representative samples from the designated material yard should be taken and tested strictly in accordance with relevant specifications and procedures.

[0077] S22: Material requirements; S221: The materials to be stabilized in in-situ cold recycling of foamed bitumen shall meet the following requirements: The maximum particle size of a single particle in a foamed asphalt stabilized recycled layer should not exceed 37.5 mm; the particle composition of the foamed asphalt stabilized recycled layer should be within the gradation range listed in Table 1.

[0078] Table 1. Gradation Range of Foamed Asphalt Cold Recyclable Materials S222: The minimum acceptable expansion rate and half-life of the base asphalt used for foaming are 10 times and 8 seconds, respectively. Asphalt that does not meet these requirements should be replaced. If the foaming requirements can be met by adding a foaming agent without affecting the properties of the asphalt itself, it can also be used.

[0079] S223: When cement is used as a recycled active filler, ordinary Portland cement, slag Portland cement, and pozzolanic Portland cement may be used. Cement with an initial setting time of 3 hours or more and a final setting time of 6 hours or more should not be used. Rapid-hardening cement, high-early-strength cement, or cement that has been damp and deteriorated should not be used. Cement should be loose, dry, and free of lumps and caking. For composite Portland cement, its strength must be tested beforehand. The cement strength grade is usually 42.5 MPa.

[0080] S224: Clean water should be used for foamed asphalt stabilization recycling. Testing should be conducted if there is any doubt about the water quality.

[0081] S23: Asphalt performance testing; S231: When designing the mix proportion, the basic index test and foaming performance test of the base asphalt must be carried out first. The requirements are shown in Table 2.

[0082] Table 2 Asphalt Technical Indicators Testing S232: After the basic asphalt index tests are completed, the foaming characteristics can be determined. The steps are as follows: S2321: The foaming temperature of asphalt is usually selected from three temperatures: 150°C, 160°C, and 170°C. S2322: The foaming water content shall be at least 4 units, typically 1.5%, 2.0%, 2.5%, and 3.0% of the asphalt mass. S2323: Heat the asphalt circulating in the testing machine to the required temperature and maintain it for at least 5 minutes before starting the test; S2324: Calibrate the asphalt injection flow rate and set a timer so that the amount of asphalt injected each time is 500g; S2325: Spray foamed asphalt into a steel drum (275mm in diameter), and use the scale provided with the testing machine to measure the maximum height of the foamed asphalt inside the drum as the maximum volume; S2326: The time taken for foamed bitumen to decay to half its maximum volume is measured using a stopwatch and is taken as the half-life of the foamed bitumen. S2327: Repeat at least three times until the readings of maximum volume and half-life are similar each time; S2328: For each temperature, repeat S2325~S2327 at at least 3 moisture contents; S2329: Plot a graph with water content (%) on the x-axis and expansion rate (multiple) and half-life (S) on the y-axis, based on experimental data, and select the foaming temperature and foaming water volume that can produce the best foaming effect.

[0083] Table 3 Recommended foamed asphalt results S24: Mineral aggregate gradation design S241: The gradation of each component material in the recycled asphalt pavement material and the new aggregate was measured; S242: Determine the composite gradation based on the gradation of the old mixture and the new additive. The gradation range is shown in Table 1. Plot the gradation curve to ensure that the designed composite gradation is within the corresponding gradation range. The designed composite gradation should be close to the median value of the gradation range in the table. If repeated adjustments are not satisfactory, the new additive should be replaced and the design should be repeated.

[0084] S25: Determination of maximum dry density and optimum moisture content; S251: When stabilizing old pavement materials with foamed asphalt, a small amount of cement or lime is usually added in combination with the foamed asphalt. Cement is commonly used in construction. When preparing test samples, the cement dosage is usually 1.5%. The cement dosage is expressed as a percentage of the cement mass to the total dry mass of the material, i.e., cement dosage = cement mass / (cement mass + dry mass of the old material to be stabilized).

[0085] S252: Determine the maximum dry density and optimum moisture content of the mixture according to the method in T0131 of the "Specifications for Testing Geotechnical Engineering for Highways" (JTG-E40).

[0086] S26: Sample preparation; S261: Calculate the dry mass of the recycled mixture sample; S262: Calculate the amount of active filler required; S263: Place the required quantity of mixture and filler into the mixing tank and dry mix for 30 seconds; S264: Calculate and determine the optimal amount of water for mixing; S265: Add water to the mixing tank and mix for 30 seconds until homogeneous; S266: Determine the amount of foamed asphalt (the amount of asphalt is generally selected as 1.5%, 2%, 2.5%, or 3%), and consider the influence of some asphalt adhering to the mixing blades of the mixing pot. The actual amount of asphalt added is usually 1.25 times the calculated value. S267: Connect the mechanical mixing plant and the foaming equipment together so that foamed asphalt can be directly sprayed into the mixing pot; S268: Turn on the mixer and mix for at least 10 seconds before spraying foamed asphalt into the mixing pot, and continue mixing for 30 seconds after spraying foamed asphalt. S269: Transfer the mixed foamed asphalt stabilized material into a container and seal it immediately to prevent moisture loss; S2610: Produce specimens immediately following the steps below, with at least 4 different foamed bitumen contents.

[0087] S27: Molded test specimen S271: Mix the various parts according to the proportion of old asphalt pavement milling material and cement in the synthetic gradation, add water corresponding to 65% of the optimum moisture content determined by the heavy compaction test to the mixture, and then add 1.5%, 2.0%, 2.5% and 3.0% of the four types of foamed asphalt respectively and mix. S272: For medium-grained gradation, the mixed material is compacted on both sides 75 times each using the Marshall compaction method to form specimens; S273: Place the sample and mold together on their side in a 60°C forced-air oven to cure until constant weight. The curing time is generally not less than 40 hours. S274: Remove the mold from the oven and place the sample directly on its side to cool for 12 hours before demolding; S28: Determine the optimal amount of foamed bitumen; S281: Each group of foamed asphalt specimens shall undergo a 15°C splitting tensile test and a 24-hour water immersion splitting tensile test. The 24-hour water immersion splitting tensile test method is as follows: the specimen is completely immersed in a 25°C constant temperature water bath for 22 hours, then completely immersed in a 15°C constant temperature water bath for 2 hours, and then immediately subjected to a 15°C splitting tensile test. The splitting tensile strength test shall be conducted according to the method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011).

[0088] Table 4. Results of Dry and Wet Splitting Strength Tests at 15°C S282: Based on the results of splitting strength and water immersion splitting strength tests, and combined with engineering experience, the optimal foamed asphalt content (OAC) is determined comprehensively.

[0089] S283: For roads with high-volume, extra-heavy, or extremely heavy traffic, if foamed asphalt mixtures are used in the surface layer structure, triaxial tests are required to determine the shear strength of the foamed asphalt mixtures to improve the long-term performance of the road. Traffic class classifications can be found in Table 6. Vibrated cylindrical specimens should have a diameter of φ-150mm and a height of h-300mm. Specific performance verification indicators are shown in Table 7. If the performance indicators of the recycled mixture do not meet the design requirements in Table 5, the mix design should be revised by adjusting the material composition.

[0090] Table 5 Technical Standards for Foamed Asphalt Recycled Mixtures Table 6 Design Traffic Load Levels Table 7 Shear Performance Requirements for Heavy and Extra Heavy Traffic Sections S3: Construction of the test section.

[0091] The specific steps of S3 are as follows: S31: Construction Preparation S311: The minimum daily temperature during the construction period of foamed asphalt in-situ cold recycling structural layer should be above 10°C; S312: Select the test section as required; and specify the following requirements for the test section: Table 8. Road surface conditions suitable for in-situ cold recycling of foamed asphalt S32: Construction plan finalized: S321: Based on experience and the characteristics of the recycling machinery used, formulate 3 to 5 different combinations of recycling machine travel speed and rotor speed. Mill the old road according to the designed recycling depth. Take representative materials after milling and send them to the laboratory for screening. Select the scheme with the gradation closest to the ideal gradation as the scheme of recycling machine travel speed and rotor speed during construction. S322: Based on the determined regenerator travel speed and rotor speed, take representative material samples after milling and send them to the laboratory for indoor mix design verification; S323: Strictly follow the relevant requirements of the "Technical Specification for Recycling Asphalt Pavement of Highway" (JTG / T5521-2019) and adopt 1 to 3 compaction schemes (including roller tonnage, rolling sequence, number of passes, etc.) to determine the most reasonable rolling scheme. S324: Select representative recycled mixtures and send them to the laboratory to determine the moisture content and maximum dry density of the recycled mixtures. Then, mold specimens and determine their wet and dry splitting strength to verify the production mix proportion. S325: Test the deflection, compaction, flatness, thickness, width and other indicators of the test section; S326: Based on the results of the test section, the final determination of the gradation of the recycled mixture, the traveling speed of the recycling machine, the rotor speed, and the compaction process of the recycled mixture during construction.

[0092] S4: In-situ cold recycling of foamed asphalt.

[0093] The specific steps of S4 are as follows: S41: Construction layout; Before reconstruction, a series of marker stakes (poles) should be placed on both sides of the road as baselines to restore the road's centerline. The spacing between the marker stakes (poles) should not exceed 20 meters for curves and 40 meters for straight sections.

[0094] S42: Original road surface treatment; Remove debris from the original road surface (including adjacent lanes and shoulders that do not require regeneration) and mark the edge lines. Remove manhole covers and similar structures from the regenerated section. Treat defects such as frost heave, ruts, subsidence, undulations, and potholes on the original road to make it basically smooth.

[0095] S43: Pre-reshaping of the original road; When the cross slope (including superelevation or camber) and longitudinal slope of the original road need to be adjusted, certain methods should be used to smooth out the original unevenness such as local bulges or depressions to meet the design requirements.

[0096] Large settlements or slope changes exceeding the thickness of the recycled layer must be treated separately before recycling.

[0097] For road sections with particularly high groundwater levels, drainage ditches (or blind drains) should be excavated at regular intervals (10-30m) on both sides of the road shoulders of the regenerated road section.

[0098] S44: Prepare newly added materials; S441: Under normal circumstances, no new materials need to be added, unless the gradation of the original pavement material is very undesirable; S442: The thickness of the added virgin material must be less than the thickness of the recycled material, and usually not exceed 5 cm. S443: Calculate the amount of newly added material: Calculate the amount of new material to be added per square meter based on the average density within the original road recycling depth; The newly added material is spread using a paver; When a paver is unavailable, a grader or loader can be used as an auxiliary tool. In this case, the cost should be calculated based on the weight or volume of each truckload of material. Calculate the stacking distance for each truckload of material, and ensure that the quantity of material in each truckload is approximately equal; S444: Within the same material yard supply route, spread or level the material from far to near to avoid insufficient or excessive material in some sections; S445: Spread the new material evenly on the old road surface, at a rate of 1000m. 2 This is a uniform section; check whether the quality of the newly added material is uniform.

[0099] S45: Cement spreading; Cement should be added using cement slurry trucks or cement spreader trucks.

[0100] Do not spread cement on the entire construction section at the same time. Instead, spread cement evenly within the working width of the cold recycling machine. After completing one working width, spread cement on another working width.

[0101] S46: Cold recycling machine milling and mixing; Arrange the construction equipment as follows: cement spreader truck - water tanker truck - hot asphalt tanker truck - recycling machine - paver - roller, and connect the corresponding pipelines. Start the construction equipment and mill and mix the road surface according to the set recycling depth. When the recycling machine starts working, the rotor should be completely cut down to the bottom of the recycled layer to break up the recycled material, so that the mixed depth of the loosened recycled material meets the design requirements. The working width of the recycling machine is 3.8 meters, and recycling requires three operations depending on the road width.

[0102] The travel speed of the cold recycling machine should be adjusted according to the road surface damage and recycling depth, generally between 4m / min and 5m / min, to minimize fluctuations in the gradation of the milled material. In areas with severe network cracking, the recycling machine's travel speed should be reduced, and the rotor speed increased. A dedicated person should follow the recycling machine to continuously check the recycling depth and assist the operator in making adjustments. For recycling machines with screeds, the thickness of the mixture behind the screed should be checked frequently. After each recycling stage, the milling hub's cutter holder and cutter head should be inspected, and any damaged parts replaced immediately.

[0103] S47: Recycled material paving; Paving operations must be carried out slowly, evenly, and continuously; the paving speed must not be changed arbitrarily or the process must not be stopped midway. Paving cannot be carried out on rainy days, and paving should also be stopped if the temperature is below 10℃.

[0104] The loose paving coefficient of foamed asphalt recycled layer is generally 1.4~1.45.

[0105] S48: Recycled material compaction; S481: Based on the different road widths, roller wheel widths, and wheel gauges, a compaction plan should be formulated to ensure that each part is compacted as many times as possible, and the sides of the road surface should be compacted 2-3 more times.

[0106] S482: A single-drum vibratory roller should be installed after the recycling machine for initial compaction. During initial compaction, the roller should first perform one pass of static compaction, closely following the recycling machine. After static compaction, high-amplitude, low-frequency vibration compaction should be used. The number of compaction passes should be sufficient to ensure that the compaction degree within the bottom 2 / 3 thickness of the recycled layer meets the specified requirements. Each compaction cycle should begin at the start of the construction section and end at the edge of the recycling machine, with the compaction width exceeding the width of the recycling section. The operating speed of the roller must not exceed 3 km / h.

[0107] S483: If wheel sticking occurs during initial compaction with a large-tonnage single-drum roller, the rubber-tired roller can be pre-sprayed with water for pre-compaction before initial compaction.

[0108] S484: After the initial compaction, a double-drum vibratory roller is used for secondary compaction with weak vibration (low amplitude, high frequency). On straight sections and horizontal curves without superelevation, when rolling from the shoulder towards the center of the road, the roller should overlap by 1 / 2 the roller width, completing one pass when the full width of the road surface is covered. Generally, 4-6 passes are required. The roller speed should be 1.5-1.7 km / h for the first two passes, and 2.0-2.5 km / h thereafter.

[0109] S485: Finally, use a rubber-tired roller for final compaction, at least 8 passes. Water can be sprayed for compaction if necessary.

[0110] S486: It is strictly forbidden for road rollers to turn around or brake suddenly on completed or ongoing road sections, and the surface of the recycled layer must be protected from damage.

[0111] S487: During the compaction process, the surface of the recycled layer should always be kept moist. If the moisture evaporates too quickly, a small amount of water should be added in time, but it is strictly forbidden to spray a large amount of water for compaction.

[0112] S49: Treatment of transverse and longitudinal seams; S491: Treatment of transverse seams: A. Downtime should be minimized during construction. B. The machinery should be strictly inspected, especially the air venting of the water pipes. Gas must be removed before the liquid reaches the spray bar. C. Pay attention to checking the amount of cement slurry or water sprayed in order to avoid excessive or insufficient application in the horizontal direction. D. When the recycling machine resumes operation at the shutdown location, the entire recycling machine must be moved back to a distance of 1.5m from the recycled material. S492: Treatment of Longitudinal Joints: The working width of the recycling machine is 3.8 meters. Recycling requires three operations depending on the road width, resulting in longitudinal joints between two adjacent work surfaces. The minimum overlap between adjacent work surfaces is 10 cm to ensure the continuity of recycled material at the longitudinal joint and to avoid unrecycled material being trapped between adjacent work surfaces. The longitudinal joint should be kept moist to facilitate bonding between materials. The location of the longitudinal joint should avoid the wheel tracks of slow-moving and heavy vehicles as much as possible.

[0113] S410: Health preservation.

[0114] After the foamed asphalt recycled base course is completed, the curing time before the upper structural layer is laid should not be less than 7 days, or the moisture content should be less than 2%.

[0115] When maintaining health in a closed-off environment, one can engage in natural health practices and generally does not need to take other measures.

[0116] When conducting health maintenance under open traffic conditions, the passage of heavy vehicles should be strictly restricted, the driving speed should be controlled within 20km / h, and vehicles are strictly prohibited from making U-turns or speeding on the regeneration layer.

[0117] To prevent damage to the surface layer from vehicle wheels, slow-cracking emulsified asphalt can be evenly spread on the recycled layer for maintenance.

[0118] In S2, the recycled materials include recycled asphalt mixture and cement, with a mineral aggregate ratio of 98.2:1.8, an asphalt foaming temperature of 160±5℃, a water content of 2.4%, a foamed asphalt content of 3.0%, an optimum moisture content of 4.8%, and a maximum dry density of 2.06 g / m³. 3 .

[0119] Although the specific embodiments of the invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the invention. Based on the technical solutions of the invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the invention.

Claims

1. A method for constructing full-depth foamed asphalt cold recycling, characterized in that, Includes the following steps: S1: Determine the mechanical configuration; S2: Determine the mix design of recycled materials; S3: Construction of the test section; S4: In-situ cold recycling of foamed asphalt; The mechanical configuration in S1 includes a recycler, a cement spreader, a tanker truck, a paver, a compaction equipment, a material transport vehicle, and a loader. The specific structure of the recycler includes an outer shell (1), a motor (2), wheels (3), a mounting cavity (4), a layered milling mechanism (5), an adjustable screening mechanism (6), and a sampling and conveying mechanism (7). The outer shell (1) has a motor (2) fixedly connected inside the front and rear positions on the left and right lower sides, and a wheel (3) is fixedly connected to the external output shaft of the motor (2). The lower side of the outer shell (1) has an installation cavity (4). The layered milling mechanism (5) is located on the left side of the mounting cavity (4); The adjustable screening mechanism (6) is located on the right side of the mounting cavity (4); The sampling and conveying mechanism (7) is located inside the right side of the outer casing (1); The specific structure of the layered milling mechanism (5) includes a hydraulic cylinder (51), a movable seat (52), a motor (53), a connecting shaft (54), a drive pulley (55), a belt (56), a milling hob (57), a connecting shaft (58), a transmission pulley (59), a belt (510), a transmission pulley (511), a connecting shaft (512), a milling hob (513), a conveying pipe (514), a screw rod (515), and a motor (516). The second motor (53) is fixedly connected to the outside of the left front side of the outer casing (1); The first connecting shaft (54) is movably connected to the lower left side of the mounting cavity (4), and the center of the front side of the first connecting shaft (54) is fixedly connected to the output shaft of the second motor (53); The drive pulley (55) is located on the rear side of the movable seat (52), and the center of the drive pulley (55) is fixedly connected to the rear side of the connecting shaft (54); The movable seat (52) is movably connected to the outside of the connecting shaft one (54) on the left side. The movable seat (52) is movably connected to the lower left side of the interior of the movable seat (52). The connecting shaft two (58) is fixedly connected to the outer rear side of the connecting shaft two (58). The connecting shaft one (59) is connected to the driving pulley (55) through the belt one (56). The movable seat (52) is movably connected to the lower right side of the interior of the movable seat (52). The connecting shaft three (512) is fixedly connected to the outer rear side of the connecting shaft three (512). The connecting shaft two (511) is connected to the connecting shaft one (59) through the belt two (510). The upper side of the first hydraulic cylinder (51) is movably connected to the upper left side of the mounting cavity (4), and the lower piston rod of the first hydraulic cylinder (51) is movably connected to the upper left side of the movable seat (52); The milling hob (57) is internally fixedly connected to the outside of the connecting shaft (54); The milling hob two (513) is internally fixedly connected to the outside of the connecting shaft three (512); The conveying pipe (514) is fixedly connected to the upper right side inside the movable seat (52), and a motor (516) is fixedly connected to the top of the conveying pipe (514). The first screw rod (515) is movably connected inside the conveying pipe (514), and the upper center of the first screw rod (515) is fixedly connected to the output shaft of the third motor (516).

2. The method for constructing a full-depth foamed asphalt cold recycling system according to claim 1, characterized in that: The adjustable screening mechanism (6) includes a fixed base (61), a guide groove (62), a screening chamber (63), a sieve hole seat (64), a sieve hole cavity (65), an adjusting sieve plate (66), a screw (67), a motor (68), a turntable (69), a fixed shaft (610), a sliding block (611), a motor (612), a driven gear (613), a driving gear (614), and a splined shaft (615). The fixed base (61) has a screening chamber (63) inside on the left side, and a guide groove (62) is provided in the center of the screening chamber (63). The fixed base (61) has a motor (68) fixedly connected to the upper right side. The sieve seat (64) is laterally movably connected inside the guide groove (62), and a sliding block (611) is fixedly connected to the right end of the sieve seat (64). The sieve seat (64) has a sieve cavity (65) in the center. The screw (67) is movably connected to the center of the right side of the sieve cavity (65), and a driven gear (613) is fixedly connected to the right end of the screw (67). The adjusting sieve plate (66) is laterally movably connected to the inside of the sieve cavity (65), and the threaded hole provided in the center of the right side of the adjusting sieve plate (66) is connected to the screw rod (67); The turntable (69) is movably connected to the upper right side of the fixed base (61). The center of the turntable (69) is fixedly connected to the lower output shaft of the motor (68). A fixed shaft (610) is fixedly connected to the lower edge of the turntable (69), and the outside of the fixed shaft (610) is movably connected to the inside of the longitudinal groove provided on the upper side of the slide block (611). The motor five (612) is fixedly connected to the lower right side of the fixed base (61), and a spline shaft (615) is fixedly connected to the output shaft on the left side of the motor five (612). The drive gear (614) is movably connected to the lower right side of the screen hole seat (64). The spline hole in the center of the drive gear (614) is connected to the spline shaft (615). The upper tooth of the drive gear (614) is connected to the lower tooth of the driven gear (613).

3. The method for constructing a full-depth foamed asphalt cold recycling system according to claim 1, characterized in that: The specific structure of the sampling and conveying mechanism (7) includes a collection trough seat (71), a second screw rod (72), a collection trough (73), a conveying hole (74), a connecting block (75), a second oil cylinder (76), a slide chute (77), a lifting and conveying channel (78), a third screw rod (79), a collection box (710), a sixth motor (711), and a seventh motor (712). The chute (77) is horizontally opened on the lower right side of the mounting cavity (4), and a horizontal collection trough seat (71) is movably connected inside the chute (77). The collection trough (73) is provided on the left side of the collection trough (71), the collection trough (74) is provided on the lower side of the collection trough (71), the motor (712) is fixedly connected to the outside of the right side of the collection trough (71), and the connecting block (75) is fixedly connected to the bottom of the collection trough (71). The second screw rod (72) is movably connected inside the conveying hole (74), and the right center of the second screw rod (72) is fixedly connected to the left output shaft of the seventh motor (712); The second hydraulic cylinder (76) is fixedly connected to the lower right side of the slide groove (77), and the end of the piston rod on the left side of the second hydraulic cylinder (76) is fixedly connected to the right side of the connecting block (75); The collection box (710) is located inside the right side of the outer shell (1); The lifting and conveying channel (78) is located inside the right side of the outer shell (1), and the upper right outlet of the lifting and conveying channel (78) is connected to the inside of the collection box (710); The motor six (711) is fixedly connected to the upper right side of the outer casing (1); The three screw rods (79) are movably connected inside the lifting and conveying channel (78), and the upper center of the three screw rods (79) is fixedly connected to the lower output shaft of the six motors (711).

4. The method for constructing a full-depth foamed asphalt cold recycling system according to claim 1, characterized in that: The specific steps of S3 are as follows: S31: Construction preparation; S311: The minimum daily temperature during the construction period of foamed asphalt in-situ cold recycling structural layer should be above 10°C; S312: Select the test section as required; S32: Construction plan finalized; S321: Based on experience and the characteristics of the recycling machinery used, formulate 3 to 5 different combinations of recycling machine travel speed and rotor speed. Mill the old road according to the designed recycling depth. Take representative materials after milling and send them to the laboratory for screening. Select the scheme with the gradation closest to the ideal gradation as the scheme of recycling machine travel speed and rotor speed during construction. S322: Based on the determined regenerator travel speed and rotor speed, take representative material samples after milling and send them to the laboratory for indoor mix design verification; S323: Use 1 to 3 compaction schemes for construction to determine the most reasonable rolling scheme; S324: Select representative recycled mixtures and send them to the laboratory to determine the moisture content and maximum dry density of the recycled mixtures. Then, mold specimens and determine their wet and dry splitting strength to verify the production mix proportion. S325: Test the deflection, compaction, flatness, thickness, width and other indicators of the test section; S326: Based on the results of the test section, the final determination of the gradation of the recycled mixture, the traveling speed of the recycling machine, the rotor speed, and the compaction process of the recycled mixture during construction.

5. The method for constructing a full-depth foamed asphalt cold recycling system according to claim 1, characterized in that: The specific steps of S2 are as follows: S21: Inspection of original road surface materials; S22: Material requirements; S23: Asphalt performance testing; S24: Mineral aggregate gradation design; S25: Determination of maximum dry density and optimum moisture content; S26: Sample preparation; S27: Molded specimen; S28: Determine the optimal amount of foamed bitumen.

6. The method for constructing a full-depth foamed asphalt cold recycling system according to claim 5, characterized in that: In S2, the recycled materials include recycled asphalt mixture and cement, with a mineral aggregate ratio of 98.2:1.8, an asphalt foaming temperature of 160±5℃, a water content of 2.4%, a foamed asphalt content of 3.0%, an optimum moisture content of 4.8%, and a maximum dry density of 2.06 g / m³. 3 .

7. The method for constructing a full-depth foamed asphalt cold recycling system according to claim 1, characterized in that: The specific steps of S4 are as follows: S41: Construction layout; S42: Original road surface treatment; S43: Pre-reshaping of the original road; S44: Prepare newly added materials; S45: Cement spreading; S46: Cold recycling machine milling and mixing; S47: Recycled material paving; S48: Recycled material compaction; S49: Treatment of transverse and longitudinal seams; S410: Health preservation.

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