Double-layer continuous paving construction technology for pavement recycling

Abstract

The present invention belongs to the technical field of highway maintenance, especially the construction technology of double-layer continuous paving for pavement recycling. Aiming at the problems, this technology mainly introduces the construction technology of double-layer continuous paving for a 9-meter-wide road, including the following steps: S1 Construction preparation; S2 Milling of foamed asphalt cold recycling; S3 Spreading of aggregate for foamed asphalt cold recycling; S4 Spreading of cement for foamed asphalt cold recycling; S5 Operation of foamed asphalt cold recycling; S6 Synchronous paving and milling of in-situ cement recycling; S7 Spreading of stone materials for synchronous paving of cold recycling of cement; S8 Spreading of cement for synchronous paving of cold recycling of cement; S9 Recycling operation of synchronous paving of cold recycling of cement; S10 Paving of synchronous paving of cold recycling of cement; S11 Compaction of synchronous paving of cold recycling of cement; S12 Paving of foamed asphalt cold recycling; S13 Compaction of foamed asphalt cold recycling; S14 Curing and opening to traffic. The double-layer continuous paving construction adopted in the present invention saves the curing time of the base course of the water-stable cold recycling mixture, speeds up the construction progress, saves the construction cost, and is of great significance to the protection of water resources and the ecological environment.

Description

Technical Field

[0001] The present invention relates to the technical field of highway maintenance, and particularly to a construction process for double-layer continuous paving of pavement recycling. Background Art

[0002] During the current highway maintenance process, the cold recycling and reuse of the base course and surface course have attracted wide attention and found new applications. The cold recycling technology can solve problems such as the stacking, abandonment, and environmental pollution of waste pavement materials, realize the recycling and reuse of waste pavement materials, reduce the exploitation of mineral resources such as stone materials, protect the environment, and reduce the cost of road maintenance and repair. Nowadays, many road base courses and surface courses need to be centrally processed and repaired. Due to the relatively low requirements for some road grades and the short construction period and tight tasks, it is necessary to design a construction process for double-layer continuous paving of pavement recycling to solve the above problems. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems in the prior art, and a construction process for double-layer continuous paving of pavement recycling is proposed.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] The construction process for double-layer continuous paving of pavement recycling proposed by the present invention mainly introduces the construction process for double-layer continuous paving of a 9-meter-wide road, including the following steps: S1 Construction Preparation; S2 Milling of Foamed Asphalt Cold Recycling; S3 Aggregate Spreading of Foamed Asphalt Cold Recycling; S4 Cement Spreading of Foamed Asphalt Cold Recycling; S5 Operation of Foamed Asphalt Cold Recycling; S6 Synchronous Paving and Milling of Cement In-situ Recycling; S7 Stone Spreading of Synchronous Paving of Cement Cold Recycling; S8 Cement Spreading of Synchronous Paving of Cement Cold Recycling; S9 Recycling Operation of Synchronous Paving of Cement Cold Recycling; S10 Paving of Synchronous Paving of Cement Cold Recycling; S11 Compaction of Synchronous Paving of Cement Cold Recycling; S12 Paving of Foamed Asphalt Cold Recycling; S13 Compaction of Foamed Asphalt Cold Recycling; S14 Curing and Opening to Traffic.

[0006] Preferably, it is specifically divided into the following steps:

[0007] S1. Construction preparation includes machine preparation and material preparation:

[0008] Machine preparation includes:

[0009] Foamed asphalt recycling unit: 3800CR system (recycling machine, asphalt tanker, water truck, etc.); 1 paver; 1 tandem roller (with strong and weak vibration adjustment), a fully hydraulic single drum roller of 20t or more; 1 rubber-tyred roller of more than 26t, 2 water trucks, and 6 transport vehicles.

[0010] One 380CR in-situ cold recycler; one full-hydraulic single-drum vibratory roller over 20t, one paver; one 30T rubber-tyred roller, two water trucks; one cement distributor, one stone distributor.

[0011] Material preparation includes:

[0012] According to the design results of the mix ratio, prepare the required raw materials, including foamed asphalt, crushed stones, cement and other materials. The remaining auxiliary materials are determined according to on-site observations.

[0013] S2. Foamed asphalt cold recycling milling:

[0014] First, the asphalt recycler mills half of the surface layer with a length of 400 meters and transports it to the designated location for stacking by transport vehicles;

[0015] Then, use a 1m milling machine to mill the old asphalt surface layer of the half-width carriageway outside the working width of the recycler in advance. The milling depth is the same as the recycling depth. Convey the milled materials to the working surface to be recycled through a conveyor belt and level them with a forklift.

[0016] S3. Aggregate spreading for foamed asphalt cold recycling:

[0017] For crushed stones, use the spreading method of a stone distributor. Calculate the spreading amount per square meter according to the mix ratio and dosage. Uniformly spread the crushed stones on the surface of the old road. During construction, calibrate the spreading amount of the crushed stones to ensure that the crushed stones are accurately spread according to the metering of the mix ratio design. The crushed stones are required to be evenly distributed in the longitudinal section and may not be fully covered in the cross section because the mixture will converge towards the middle conveyor belt position during milling and mixing by the recycler, and the mixture will continue to be mixed during the convergence process;

[0018] After the spreading of the crushed stones is completed, calibrate the spreading amount of the crushed stones per square meter on-site to determine the final spreading effect and quality.

[0019] S4. Cement spreading for foamed asphalt cold recycling:

[0020] After the spreading of the crushed stones is completed, for cement, use the spreading method of a cement distributor. The additives are also spread using a distributor. Calculate the spreading amount per square meter of the cement content according to the design results of the mix ratio.

[0021] The spreading amount of the cement should be calibrated on-site or locally controlled by the total amount. The cement spreading is required to be evenly distributed in the longitudinal section and may not be fully covered in the cross section because the mixture will converge towards the middle conveyor belt position during milling and mixing by the recycler. Once the cement spreading is completed, no other vehicles are allowed to enter the construction area except for the recycler (including auxiliary equipment).

[0022] S5. Foamed asphalt cold recycling operation:

[0023] Start the construction equipment and loosen and mix the road surface according to the set regeneration depth. The recycled mixture is transported to the transport vehicle through the conveyor belt of the recycling machine, and the transport vehicle transports it to the starting position of the foamed asphalt cold recycling paving and waits. The recycling unit must carry out the recycling operation at a constant speed and continuously, and shall not change the speed randomly or stop midway. The recycling construction speed shall be 3 - 6 m / min, and the additional water consumption and asphalt dosage are determined by the results of the mix design.

[0024] S6. Synchronous paving of in-situ cement recycling milling:

[0025] After the foamed asphalt cold recycling machine finishes recycling and mixing, the original old road base is exposed. Then, a 1m milling machine is used to mill the old road base of the half-width carriageway outside the working width of the recycling machine in advance. The milling depth is the same as the regeneration depth. The milled material is transported to the working surface to be recycled through the conveyor belt and leveled by a forklift.

[0026] S7. Synchronous paving of in-situ cement recycling stone spreading:

[0027] The crushed stones are spread by a spreader. Calculate the spreading amount per square meter according to the dosage based on the mix ratio. The aggregate should be kept dry, and local total control is adopted for the aggregate. When there are no conditions, manual spreading can also be adopted, but when manually spreading, grid lines should be marked on the road surface with lime powder in advance. Total control should be carried out according to an area of every 100 m2 - 300 m2, and the spreading should be of uniform thickness.

[0028] S8. Synchronous paving of in-situ cement recycling cement spreading:

[0029] The method of spreading by a spreader can be adopted. The cement spreading amount should be calibrated on-site or local total control is adopted. The cement spreader is generally 2.5m, and the recycling width is 3.8m. When the spreader spreads once, the cement dosage corresponding to the width should be converted. The cement spreading requires uniform distribution in the longitudinal section, and it does not need to cover the entire cross-section because the mixture will converge towards the middle conveyor belt position during the milling and mixing by the recycling machine.

[0030] S9. Synchronous paving of in-situ cement recycling operation, including the following steps:

[0031] (1) Connect the required construction machines and tools end to end in sequence at the construction starting point and connect the corresponding pipelines;

[0032] (2) Start the construction equipment and mill and mix the road surface according to the set regeneration depth. The recycling unit must carry out the recycling operation slowly, evenly and continuously, and shall not change the speed randomly or stop midway. The recycling construction speed depends on the type of the recycling machine and the recycled material, and shall be 3 - 6 m / min;

[0033] (3) On straight lines and flat curves without superelevation, the regenerator should first start along the outer side of the road width and then gradually work towards the inner side of the road width; on flat curves with superelevation, the regenerator should first start along the inner side of the road width and then gradually work towards the outer side of the road width;

[0034] (4) Consider using talcum powder to draw lines on the reclaimed pavement as a guide for the reclaimer to ensure that the reclaimer moves in the correct direction. When the cutting depth of the reclaimer needs to be adjusted in special circumstances, it should be adjusted slowly (within 3mm at a time) to avoid obvious misalignment and avoid height differences when the subsequent paver is paving;

[0035] (5) There should be a dedicated person following the regenerator to check the regeneration depth, cement content and water content at any time, and cooperate with the regenerator operator to make adjustments;

[0036] (6) 4 to 5 people should be arranged behind the regenerator to handle the edge separation and clean up the impurities in the mixture and the residual material at the starting position of each cut to prevent affecting the longitudinal joints, transverse joints, flatness and density of the recycled materials;

[0037] (7) During the construction process, if there is any doubt about the gradation of the mixture, the regeneration depth, or the amount of water injected, construction should be stopped and continued only after the problems are resolved.

[0038] S10, synchronous paving of cement cold recycling paving, specifically comprising the following steps:

[0039] (1) During paving construction, attention should be paid to controlling the cross slope and thickness;

[0040] (2) During the paving process, the amplitude of the screed plate and the vibration frequency of the rammer should be reasonably selected. Generally, the cold recycled mixture should be treated with the method of "the vibration frequency of the rammer is greater than the amplitude of the screed plate" to improve the initial compaction of the cold recycled mixture. The gap at the widened hinge of the screed plate should be carefully adjusted to prevent marks on the road surface after paving;

[0041] (3) During the paving process, the paver must control the height of the material level sensor so that the spiral feeder in the storage box is always buried in the cold recycled mixture to a height of not less than 3 / 4, so as to reduce the segregation of the cold recycled mixture during the paving process. When paving or patching by hand, the buckle shovel method should be used instead of the flat throwing method; while paving and patching, the hand force should be consistent to avoid artificial segregation of the cold recycled mixture;

[0042] (4) The paving machine screed must be tightly spliced ​​without any gaps to prevent the particles from getting stuck and leaving streaks on the pavement;

[0043] (5) When installing and operating the paver, anti-segregation measures for the mixture should be taken, such as reducing the ground clearance of the front baffle of the feeder. A special person should be arranged behind the paver to eliminate segregation phenomena, remove the local concentrated area of coarse aggregates, and fill it with newly mixed mixture.

[0044] (6) Flatness control: After the paver finishes paving, the quality inspector should promptly use a three-meter straightedge to detect the flatness, especially at the starting and stopping positions of the paver. The areas that do not meet the requirements should be leveled manually in a timely manner.

[0045] (7) At the longitudinal lap joint, manual raking is used to collect the material to ensure that the road surface will not be higher than the already compacted road surface when the roller compacts.

[0046] S11. Synchronous paving and cold recycling compaction of cement: The machine body includes the following steps:

[0047] (1) The recommended compaction construction process is:

[0048] Rolling stage Roller type / quantity Number of rolling passes Rolling speed (km / h) Initial compaction 13t double steel wheel Static compaction for 2 passes 4-6 Re-compaction Full hydraulic single steel wheel over 20t and rubber-tyred roller over 30t Single steel wheel: vibration before and after for 3 - 5 passes, rubber-tyred roller: kneading for 4 - 6 passes 2-4 Final compaction 13t double steel wheel Static compaction for 1 pass 2-4

[0049] (2) During the compaction process, the surface of the recycled layer should always be kept moist. If the water evaporates too quickly, water should be sprinkled in a timely manner, but the amount of water should not be too large.

[0050] (3) To avoid the mixture being pushed and bulged during compaction, the driving wheel should face the paver during compaction, and the compaction should be carried out from the outside to the center. On the superelevation section, it should be compacted from low to high, and on the slope, the driving wheel should be compacted from low to high.

[0051] (4) During the compaction process, if there are phenomena such as "springiness", looseness, and peeling, it should be turned over and remixed (adding an appropriate amount of cement) or treated by other methods in a timely manner to meet the quality requirements.

[0052] (5) After each section of compaction is completed and the compaction degree is inspected and qualified, the in-situ recycling construction of foamed asphalt should be carried out immediately (it must be completed within the initial setting time of the cement).

[0053] S12. In-situ paving of foamed asphalt cold recycling:

[0054] After the in-situ cold recycling compaction of cement is completed and the compaction degree is detected and qualified, the foamed asphalt cold recycling paver is in place. The transport vehicle loaded with foamed asphalt mixture is docked with the paver, and the paver is used for paving. The paving coefficient is determined according to the model of the paver. The thickness and flatness are controlled by an aluminum alloy beam in the middle. The thickness and flatness of the recycled layer are strictly controlled to ensure that the cross slope of the road arch meets the design requirements.

[0055] S13. Compaction of foamed asphalt cold recycling, specifically including the following steps:

[0056] (1) Behind each paver, follow with 1 vibrating roller for compaction. The compaction length each time is about 100m. Then, use 1 single-drum roller and 1 pneumatic tire roller respectively for compaction, with distinct layers and obvious demarcation signs set.

[0057] (2) Compaction must follow the principles of "starting from light to heavy, from slow to fast, from static to vibrating, from the edge to the middle, and from low to high".

[0058] (3) Determine the compaction combination as follows: the double-drum roller vibrates after a static pass at the front for 1 time → the vibrating roller vibrates strongly at the front and back for 3 times → the pneumatic tire roller stabilizes the pressure for 4 times → the double-drum roller makes a static pass for 1 time. Compact until there are no wheel marks. During the compaction process, use the sand replacement method to detect the compaction degree at any time. When it is unqualified, repeat the compaction until the detection meets the compaction degree requirements. After the detection shows that the compaction degree meets the requirements, the compaction end time of the foamed asphalt should be controlled to be completed before the initial setting time of the base cement.

[0059] S14, Curing and Opening to Traffic:

[0060] (1) When curing under the condition of closed traffic, natural curing can be carried out. Generally, no measures are required, and vehicle passage is prohibited during the curing period.

[0061] (2) When a complete base and surface layer core sample can be taken by a core drill with a Ф150mm drill bit for the regenerated layer, the curing can be ended.

[0062] (3) When it is necessary to open to traffic after curing, a layer of slow-cracking emulsified asphalt should be promptly sprayed after compaction, and the spraying amount should be 0.3kg / ㎡ - 0.6kg / ㎡.

[0063] Compared with the prior art, the present invention provides a pavement regeneration double-layer continuous paving construction process, which has the following beneficial effects:

[0064] 1. For this pavement regeneration double-layer continuous paving construction process, through a multi-functional rapid detection vehicle, quickly detect pavement diseases, and assist with a ground-penetrating radar to comprehensively understand the hidden diseases within the pavement structure, providing a basis for pavement disease treatment, and thus ensuring the comprehensive elimination of pavement problems.

[0065] 2. For this pavement regeneration double-layer continuous paving construction process, by adopting in-situ cold recycling of cement based on synchronous paving, the new in-situ cold recycler adopts a down-cutting method, which very well ensures the uniformity of the recycled mixture.

[0066] 3. For this pavement regeneration double-layer continuous paving construction process, the recycled mixture is synchronously conveyed to the paver through a conveyor belt, and after being paved by the paver, it is compacted, ensuring the uniformity of the mixture and the pavement flatness.

[0067] 4. The double-layer continuous paving construction technology for pavement recycling shortens the curing time of in-situ cold recycling of cement from the original 7 days to 2 - 3 days by adding vibration-free and curing-free agents during base recycling. While shortening the construction period and improving efficiency, it will not reduce the due strength of the pavement.

[0068] 5. The double-layer continuous paving construction technology for pavement recycling adopts the form of double-layer continuous paving of in-situ cold recycled base of cement and in-situ cold recycled lower surface layer of foamed asphalt through synchronous paving. The base and surface layer are cured together, shortening the construction period. The interlayer connection is tight. When extracting core samples, the surface layer and the base can be taken out together without spreading prime coat oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a schematic diagram of the construction process flow of the double-layer continuous paving construction technology for pavement recycling proposed by the present invention.

[0070] Figure 2 It is a schematic diagram of the pavement layered structure of the double-layer continuous paving construction technology for pavement recycling proposed by the present invention.

[0071] In the figure: 1. AC-13 (SBS) modified asphalt concrete layer; 2. Foamed asphalt cold recycled layer; 3. Cement stabilized crushed stone cold recycled layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0072] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0073] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0074] Refer to Figure 1 - 2 , the double-layer continuous paving construction technology for pavement recycling includes the following step processes: S1 Construction preparation; S2 Milling of foamed asphalt cold recycling; S3 Aggregate spreading of foamed asphalt cold recycling; S4 Cement spreading of foamed asphalt cold recycling; S5 Operation of foamed asphalt cold recycling; S6 Milling of in-situ recycled cement through synchronous paving; S7 Stone spreading of in-situ cold recycled cement through synchronous paving; S8 Cement spreading of in-situ cold recycled cement through synchronous paving; S9 Recycling operation of in-situ cold recycled cement through synchronous paving; S10 Paving of in-situ cold recycled cement through synchronous paving; S11 Compaction of in-situ cold recycled cement through synchronous paving; S12 Paving of foamed asphalt cold recycling; S13 Compaction of foamed asphalt cold recycling; S14 Curing and opening to traffic.

[0075] In the specific implementation manner, it is specifically divided into the following steps:

[0076] S1. Construction preparation includes machinery preparation and material preparation:

[0077] Machinery preparation includes:

[0078] Foamed asphalt recycling unit: 3800CR system (recycling machine, asphalt tanker, water truck, etc.); 1 paver; 1 tandem roller (with strong and weak vibration adjustment), a full-hydraulic single-drum roller of 20t or more; 1 rubber-tyred roller of more than 26t, 2 water trucks, 6 transport vehicles;

[0079] 1 in-situ cold recycling machine 380CR; 1 full-hydraulic single-drum vibratory roller of more than 20t, 1 paver; 1 30T rubber-tyred roller, 2 water trucks; 1 cement spreader, 1 stone spreader.

[0080] Material preparation includes:

[0081] According to the design results of the mix ratio, prepare the required raw materials, including foamed asphalt, crushed stone, cement and other materials, and the remaining auxiliary materials are determined according to the on-site observation requirements.

[0082] S2. Foamed asphalt cold recycling milling:

[0083] First, the asphalt recycling machine mills half of the surface course, with a length of 400 meters, and transports it to the designated location for stacking by transport vehicle;

[0084] Then, use a 1m milling machine to mill the old asphalt surface course of the half-width carriageway outside the working width of the recycling machine in advance. The milling depth is the same as the recycling depth. Convey the milled material to the working surface to be recycled through a conveyor belt and level it with a forklift.

[0085] S3. Foamed asphalt cold recycling aggregate spreading:

[0086] For the crushed stone, use the method of spreading by a spreader. Calculate the spreading amount per square meter according to the mix ratio and the dosage. Uniformly spread the crushed stone on the old road surface. During construction, calibrate the spreading amount of the crushed stone to ensure that the crushed stone is accurately spread according to the measurement of the mix ratio design. The crushed stone spreading is required to be evenly distributed in the longitudinal section, and it may not cover the entire cross section because the mixture will converge towards the middle conveyor belt position during milling and mixing by the recycling machine, and the mixture will continue to be mixed during the convergence process;

[0087] After the crushed stone spreading is completed, calibrate the spreading amount of the crushed stone per square meter on-site to determine the final spreading effect and quality.

[0088] S4. Foamed asphalt cold recycling cement spreading:

[0089] After the gravel is spread, the cement is spread by a spreader truck, and the additive is also spread by a spreader truck. According to the mix design results, the cement dosage is calculated according to the dosage to obtain the spreading amount per square meter.

[0090] The cement spreading amount should be calibrated on-site or controlled by local total amount. The cement spreading is required to be evenly distributed in the longitudinal section, and the cross-section may not be fully covered because the mixture will converge to the middle conveyor belt position during milling and mixing by the recycling machine. Once the cement spreading is completed, no other vehicles are allowed to enter the construction area except the recycling machine (including auxiliary equipment).

[0091] S5. Foamed asphalt cold recycling operation:

[0092] Start the construction equipment and loosen and mix the road surface according to the set recycling depth. The recycled mixture is transported to the transport vehicle through the conveyor belt of the recycling machine, and the transport vehicle transports it to the starting position of the foamed asphalt cold recycling paving and waits. The recycling unit must carry out the recycling operation at a constant speed and continuously, and shall not change the speed randomly or pause in the middle. The recycling construction speed should be 3 - 6 m / min, and the additional water consumption and asphalt dosage are determined by the mix design results.

[0093] S6. Synchronous paving of in-situ cement recycling milling:

[0094] After the foamed asphalt cold recycling machine recycles and mixes, the original old road base is exposed. Then, a 1m milling machine is used to mill the old road base of the half-width driving lane outside the working width of the recycling machine in advance. The milling depth is the same as the recycling depth. The milled material is transported to the working surface to be recycled through the conveyor belt and leveled by a forklift.

[0095] S7. Synchronous paving of in-situ cement recycling spreading of stone materials:

[0096] The gravel is spread by a spreader truck. The spreading amount per square meter is calculated according to the dosage according to the mix ratio. The aggregate should be kept dry, and the aggregate is controlled by local total amount. When there is no condition, manual spreading can also be adopted, but when manually spreading, grid lines should be marked with lime powder on the road surface in advance, and the total amount should be controlled preferably according to the area of every 100 m2 - 300 m2, and the spreading should be of uniform thickness.

[0097] S8. Synchronous paving of in-situ cement recycling spreading of cement:

[0098] The method of spreading by a spreader truck can be adopted. The cement spreading amount should be calibrated on-site or controlled by local total amount. The cement spreader is generally 2.5m, and the recycling width is 3.8m. The cement amount for one pass of the spreader should be converted into the corresponding width. The cement spreading is required to be evenly distributed in the longitudinal section, and the cross-section may not be fully covered because the mixture will converge to the middle conveyor belt position during milling and mixing by the recycling machine.

[0099] S9. Synchronous paving of cement cold recycling operation, including the following steps:

[0100] (1) At the starting point of the construction, connect all the required construction machines and tools end to end in sequence and connect the corresponding pipelines;

[0101] (2) Start the construction equipment and mill and mix the road surface according to the set recycling depth. The recycling unit must carry out the recycling operation slowly, evenly and continuously, and shall not change the speed randomly or stop midway. The recycling construction speed depends on the type of the recycling machine and the recycling material, and should be 3 - 6 m / min;

[0102] (3) On straight sections and horizontal curve sections without superelevation, the recycling machine should start from the outside of the road width first and then gradually construct towards the inside of the road width; on horizontal curve sections with superelevation, the recycling machine should start from the inside of the road width first and then gradually construct towards the outside of the road width;

[0103] (4) It should be considered to draw lines with talcum powder on the recycled road surface as the direction guide for the recycling machine to ensure that the recycling machine moves forward in the correct direction. When the cutting depth of the recycling machine needs to be adjusted in case of special circumstances, it should be adjusted slowly (the one-time height adjustment is within 3 mm) to avoid obvious stepped phenomena and height differences when the subsequent paver is paving;

[0104] (5) There should be a special person following behind the recycling machine to check the recycling depth, cement content and water content at any time and cooperate with the operator of the recycling machine for adjustment;

[0105] (6) It is advisable to arrange 4 - 5 people behind the recycling machine to handle the edge segregation, clean the impurities in the mixture and the surplus materials at the starting position of each pass to prevent affecting the longitudinal joints, transverse joints, flatness and compactness of the recycled materials;

[0106] (7) During the construction process, if there are any doubts about the gradation of the mixture, recycling depth and water injection volume, the construction should be stopped and continued after the problems are solved.

[0107] S10. Synchronous paving of cement cold recycling, specifically including the following steps:

[0108] (1) Pay attention to controlling the cross slope and thickness during paving construction;

[0109] (2) During the paving process, the amplitude of the screed and the vibration frequency of the tamper should be reasonably selected. Generally, for cold recycled mixtures, the method of "the vibration frequency of the tamper is greater than the amplitude of the screed" is preferably adopted to improve the initial compaction degree of the cold recycled mixture. The gap at the hinge where the screed is widened should be carefully adjusted tightly to prevent traces on the road surface after paving;

[0110] (3) During the paving process of the paver, it is necessary to control the height of the material level sensor well, so that the screw feeder in the storage hopper is always buried in the cold recycled mixture by no less than 3 / 4 of its height, in order to reduce the segregation of the cold recycled mixture during the paving process. When paving or patching manually, the shoveling process should be adopted, and the flat throwing method is not suitable; while paving, level up at the same time, and the force of hand should be consistent to avoid causing artificial segregation of the cold recycled mixture;

[0111] (4) The screed of the paver must be spliced tightly without any gaps to prevent the particles from getting stuck and pulling out streaks on the pavement;

[0112] (5) During the installation and operation of the paver, measures to prevent segregation of the mixture such as reducing the height of the front baffle of the feeder from the ground should be taken. A special person should be arranged behind the paver to eliminate the segregation phenomenon, shovel the local area where coarse aggregates are concentrated, and fill it with newly mixed mixture;

[0113] (6) Flatness control: After the paver finishes paving, the quality inspector should promptly use a three-meter straightedge to detect the flatness, especially the flatness at the starting and stopping positions of the paver. The places that do not meet the requirements should be leveled manually in a timely manner;

[0114] (7) At the longitudinal lap joint, use manual pushing and raking to collect the material to ensure that the road surface will not be higher than the already compacted road surface when the roller compacts.

[0115] S11. Synchronous paving and cement cold recycling compaction: The machine body includes the following steps:

[0116] The recommended compaction construction process is:

[0117] Rolling stage Roller type / quantity Number of rolling passes Rolling speed (km / h) Initial compaction 13t double steel wheel Static compaction for 2 passes 4-6 Re-compaction Full hydraulic single steel wheel over 20t and rubber-tyred roller over 30t Single steel wheel: vibration before and after for 3 - 5 passes, rubber-tyred roller: kneading for 4 - 6 passes 2-4 Final compaction 13t double steel wheel Static compaction for 1 pass 2-4

[0118] (2) During the compaction process, the surface of the recycled layer should always be kept moist. If the water evaporates too quickly, water should be sprinkled in time, but the amount of water should not be too large;

[0119] (3) To avoid the mixture being pushed and crowded to form bumps during compaction, the driving wheel should be facing the paver during compaction, and compact from the outside to the center. On the superelevation section, compact from low to high, and on the slope, the driving wheel should be compacted from low to high;

[0120] (4) During the compaction process, if there are phenomena such as "springiness", looseness, and peeling, it should be turned over and remixed (adding an appropriate amount of cement) or treated by other methods to meet the quality requirements;

[0121] (5) After each section of compaction is completed and the compaction degree is inspected and qualified, the in-situ recycling construction of foamed asphalt should be carried out immediately (it must be completed within the initial setting time of the cement).

[0122] S12. Foamed asphalt cold recycling paving:

[0123] After the in-situ cold recycling of cement is rolled and the compaction degree is qualified, the foamed asphalt cold recycling paver is in place. The transport vehicle loaded with foamed asphalt mixture is docked with the paver, and the paver is used for paving. The paving coefficient is determined according to the type of the paver. The thickness and flatness are controlled by aluminum alloy beams in the middle. The thickness and flatness of the recycled layer are strictly controlled to ensure that the cross slope of the road arch meets the design requirements.

[0124] S13. Foamed asphalt cold recycling rolling, specifically including the following steps:

[0125] (1) Behind each paver, follow 1 vibratory roller for rolling. The length of one-time rolling is about 100m, and then 1 single-drum roller and 1 pneumatic tire roller are used for rolling respectively. The layers are distinct, and obvious demarcation marks are set.

[0126] (2) The rolling must follow the principles of "from light to heavy, from slow to fast, from static to vibrating, from edge to middle, from low to high".

[0127] (3) Determine the rolling combination for compaction. The double-drum roller vibrates after static pressing for 1 pass → the vibratory roller vibrates greatly back and forth for 3 passes → the pneumatic tire roller stabilizes the pressure for 4 passes → the double-drum roller statically presses for 1 pass. Roll until there are no wheel marks. During the rolling process, the compaction degree is detected by the sand replacement method at any time. When it is unqualified, repeat the rolling until the compaction degree requirement is met. After the compaction degree meets the requirement through detection, the end time of the foamed asphalt rolling should be controlled to be completed before the initial setting time of the base cement.

[0128] S14. Curing and opening to traffic:

[0129] (1) When curing under the condition of closed traffic, natural curing can be carried out. Generally, no measures need to be taken, and vehicle passage is prohibited during the curing period.

[0130] (2) When the core samples of the base and surface layers can be taken out completely by a core drill with a Ф150mm drill bit for the recycled layer, the curing can be ended.

[0131] (3) When it is necessary to open to traffic after curing, a layer of slow-cracking emulsified asphalt should be sprayed in time after the compaction is completed. The spraying amount should be 0.3kg / ㎡ - 0.6kg / ㎡.

[0132] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Double-layer continuous paving construction technology for pavement recycling, Characterized in that, Specifically includes the following steps and processes: S1. Construction preparation; S2. Foamed asphalt cold recycling milling: First, the asphalt recycling machine mills half of the road surface layer with a length of 400 meters and transports it to the designated location for stacking by a transport vehicle; then, a 1m milling machine is used to mill the old asphalt surface layer of the half-width carriageway outside the working width of the recycling machine in advance. The milling depth is the same as the recycling depth. The milled material is conveyed to the working surface to be recycled by a conveyor belt and leveled by a forklift; S3. Aggregate spreading for foamed asphalt cold recycling: The crushed stones are spread by a spreading vehicle. According to the mix ratio, the spreading amount per square meter is calculated according to the dosage. The crushed stones are evenly spread on the old road surface. During construction, the spreading amount of the crushed stones is calibrated to ensure that the crushed stones are accurately spread according to the metering designed by the mix ratio. The spreading of the crushed stones is required to be evenly distributed in the longitudinal section; After the spreading of the crushed stones is completed, the spreading amount of the crushed stones per square meter is corrected on-site to determine the final spreading effect and quality; S4. Cement spreading for foamed asphalt cold recycling: After the spreading of the crushed stones is completed, the cement is spread by a spreading vehicle, and the additives are also spread by a spraying vehicle. According to the design result of the mix ratio, the cement content is calculated according to the dosage for the spreading amount per square meter; The spreading amount of the cement should be calibrated on-site or locally controlled by the total amount. The spreading of the cement is required to be evenly distributed in the longitudinal section. Once the spreading of the cement is completed, no vehicles other than the recycling machine are allowed to enter the construction area; S5. Foamed asphalt cold recycling operation: Start the construction equipment, loosen and mix the road surface according to the set recycling depth. The recycled mixture is transported to the transport vehicle through the conveyor belt of the recycling machine. The transport vehicle transports it to the starting position of the foamed asphalt cold recycling paving and waits. The recycling unit must carry out the recycling operation at a constant speed and continuously, and shall not change the speed randomly or stop midway. The recycling construction speed is 3-6m / min, and the additional water consumption and asphalt consumption are determined by the design result of the mix ratio; S6. Synchronous paving of cement in-situ recycling milling: After the foamed asphalt cold recycling machine regenerates and mixes, the original old road base is exposed. Then, a 1m milling machine is used to mill the old road base of the half-width carriageway outside the working width of the recycling machine in advance. The milling depth is the same as the recycling depth. The milled material is conveyed to the working surface to be recycled by a conveyor belt and leveled by a forklift; S7. Synchronous paving of cement cold recycling stone spreading; S8. Synchronous paving of cement cold recycling cement spreading; S9. Synchronous paving of cement cold recycling regeneration operation; S10. Synchronous paving of cement cold recycling paving; S11. Synchronous paving of cement cold recycling compaction; S12. After the compaction of the cement in-situ cold recycling is completed and the compaction degree is qualified, the foamed asphalt cold recycling paver is in place. The transport vehicle loaded with the foamed asphalt mixture is docked with the paver, and the paving is carried out by the paver. The paving coefficient is determined according to the type of the paver. The thickness and flatness are controlled by an aluminum alloy beam in the middle. The thickness and flatness of the recycled layer are strictly controlled to ensure that the cross slope of the road arch meets the design requirements; S13. Foamed asphalt cold recycling compaction; S14. Curing and opening to traffic.

2. In the double-layer continuous paving construction technology for pavement recycling according to claim 1, Characterized in that, Specifically, it is divided into the following steps: S1. Construction preparation includes machinery preparation and material preparation: Machinery preparation includes: 3800CR foamed asphalt recycling unit, and the 3800CR foamed asphalt recycling unit includes a recycling machine, an asphalt tanker truck and a water truck; 1 paver; 1 tandem steel wheel roller with strong and weak vibration adjustment, a full hydraulic single steel wheel roller of 20t or more; 1 rubber-tyred roller of more than 26t, 2 water trucks, and 6 transport vehicles; 1 380CR in-situ cold recycling machine; 1 full hydraulic single steel wheel vibratory roller of more than 20t, 1 paver; 1 30T rubber-tyred roller, 2 water trucks; 1 cement spreader, 1 stone spreader; Material preparation includes: According to the design results of the mix ratio, prepare the required raw materials, including foamed asphalt, crushed stones, and cement materials; S2. Foamed asphalt cold recycling milling: First, the asphalt recycling machine mills half of the surface layer with a length of 400 meters and transports it to a designated location for stacking by a transport vehicle; Then, use a 1m milling machine to mill the old asphalt surface layer of the half-width driving lane outside the working width of the recycling machine in advance. The milling depth is the same as the recycling depth. Convey the milled materials to the working surface to be recycled through a conveyor belt and level them with a forklift; S3. Aggregate spreading for foamed asphalt cold recycling: For crushed stones, use the spreading method of a spreader truck. Calculate the spreading amount per square meter according to the mix ratio and usage; evenly spread the crushed stones on the old road surface. During construction, calibrate the spreading amount of the crushed stones to ensure that the crushed stones are accurately spread according to the metering of the mix ratio design. The crushed stone spreading is required to be evenly distributed in the longitudinal section and not fully covered in the cross section because the mixture will converge towards the middle conveyor belt position during milling and mixing by the recycling machine, and the mixture will continue to be mixed during the convergence process; After the crushed stone spreading is completed, calibrate the spreading amount of crushed stones per square meter on-site to determine the final spreading effect and quality; S4. Cement spreading for foamed asphalt cold recycling: After the crushed stone spreading is completed, for cement, use the spreading method of a spreader truck. Additives are also spread using a spreader truck. According to the design results of the mix ratio, calculate the spreading amount per square meter according to the cement content and usage; The cement spreading amount should be calibrated on-site or locally controlled by the total amount. The cement spreading is required to be evenly distributed in the longitudinal section and not fully covered in the cross section because the mixture will converge and be mixed towards the middle conveyor belt position during milling and mixing by the recycling machine; once the cement spreading is completed, no vehicles other than the recycling machine are allowed to enter the construction area; S5. Foamed asphalt cold recycling operation: Start the construction equipment and loosen and mix the road surface according to the set recycling depth; the recycled mixture is transported to the transport vehicle through the conveyor belt of the recycling machine, and the transport vehicle transports it to the starting position of the foamed asphalt cold recycling paving and waits; the recycling unit must carry out the recycling operation at a constant speed and continuously, and shall not change the speed randomly or pause midway. The recycling construction speed is 3 - 6m / min, and the additional water consumption and asphalt consumption are determined by the design results of the mix ratio; S6. Synchronous paving and in-situ cement recycling milling: After the foamed asphalt cold recycling machine finishes recycling and mixing, the original old road base is exposed. Then, a 1m milling machine is used to mill the old road base of the half-width carriageway outside the working width of the recycling machine in advance. The milling depth is the same as the recycling depth. The milled materials are transported to the working surface to be recycled through a conveyor belt and leveled by a forklift. S7. Synchronously paving cement cold recycling and spreading stones: For crushed stones, the spreading method of a spreading vehicle is adopted. Calculate the spreading amount per square meter according to the dosage based on the mix ratio. The aggregate should be kept dry, and local total control is adopted for the aggregate. When there is no condition, manual spreading is adopted, but when manually spreading, grid lines should be marked on the road surface with lime powder in advance, and total control should be carried out according to the area of every 100m² - 300m². The spreading should be of uniform thickness. S8. Synchronously paving cement cold recycling and spreading cement: For the spreading amount of cement by the spreading vehicle method, it should be calibrated on-site or local total control is adopted. The cement spreading vehicle is 2.5m, and the recycling width is 3.8m. When the spreading vehicle spreads once, it is necessary to convert it into the cement dosage corresponding to the corresponding width. The cement spreading requires uniform distribution in the longitudinal section and not full coverage in the cross section because the mixture will converge towards the middle conveyor belt position during milling and mixing by the recycling machine. S9. Synchronously paving cement cold recycling and recycling operation, including the following steps: (1) At the construction starting point, connect all the required construction machines and tools end to end in sequence and connect the corresponding pipelines. (2) Start the construction equipment and mill and mix the road surface according to the set recycling depth. The recycling unit must carry out the recycling operation slowly, evenly and continuously, and shall not change the speed randomly or stop midway. The recycling construction speed depends on the type of the recycling machine and the recycling materials, and is 3 - 6m / min. (3) On straight sections and flat curve sections without superelevation, the recycling machine should start from the outside of the road width first and then gradually construct towards the inside of the road width; on flat curve sections with superelevation, the recycling machine should start from the inside of the road width first and then gradually construct towards the outside of the road width. (4) It should be considered to draw lines with talcum powder on the recycled road surface as the direction guidance for the recycling machine to ensure that the recycling machine moves forward in the correct direction; when the cutting depth of the recycling machine needs to be adjusted in case of special circumstances, adjust it slowly to avoid obvious stepped phenomena and height differences when the subsequent paver is paving. (5) There should be a special person following behind the recycling machine to check the recycling depth, cement content and water content at any time and cooperate with the recycling machine operator for adjustment. (6) Arrange 4 - 5 people behind the recycling machine to handle the edge segregation, clean the impurities in the mixture and the surplus materials at the starting position of each pass to prevent affecting the longitudinal joint, transverse joint, flatness and compactness of the recycled materials. (7) During the construction process, when there are any doubts about the gradation of the mixture, recycling depth and water injection amount, the construction should be stopped. S10. Synchronously paving cement cold recycling and paving, specifically including the following steps: (1) During paving construction, attention should be paid to controlling the cross slope and thickness. (2) During the paving process, the amplitude of the screed and the vibration frequency of the tamper should be reasonably selected; for the cold recycled mixture, the method of "the vibration frequency of the tamper is greater than the amplitude of the screed" is adopted; the gap at the articulated joint of the widened screed should be carefully adjusted to be tight. (3)During the paving process of the paver, it is necessary to control the height of the material level sensor well, so that the screw feeder in the storage bin is always buried in the cold recycled mixture by no less than 3 / 4 of its height, in order to reduce the segregation of the cold recycled mixture during the paving process; when paving or patching manually, the shoveling process should be adopted, and the method of flat throwing should be avoided; while paving, level it up at the same time, and the force of the hand should be consistent; (4)The screed of the paver must be spliced tightly without any gaps to prevent the granular materials from being stuck and pulling out streaks on the pavement; (5)During the installation and operation of the paver, measures to prevent the segregation of the mixture should be taken by reducing the ground clearance of the front baffle of the feeder. Special personnel should be arranged behind the paver to eliminate the segregation phenomenon, shovel the local areas where coarse aggregates are concentrated, and fill them with newly mixed mixture; (6)Flatness control: After the paver finishes paving, the quality inspector should promptly use a three-meter straightedge to detect the flatness, including the flatness at the starting and stopping positions of the paver. The places that do not meet the requirements should be leveled manually in a timely manner; (7)At the longitudinal lap joint, use a manual push rake to collect the materials to ensure that the road surface will not be higher than the already compacted road surface when the roller compacts; S11. Synchronous paving and cold recycling compaction of cement: The machine body includes the following steps: (1)The recommended compaction construction process is: In the initial compaction stage, use a 13t double steel wheel roller to compact statically for 2 passes at a speed of 4 - 6 km / h; In the recompaction stage, use a full hydraulic single steel wheel of more than 20t and a rubber tire roller of more than 30t. The single steel wheel vibrates front and back for 3 - 5 passes, and the rubber tire roller kneads for 4 - 6 passes at a speed of 2 - 4 km / h; In the final compaction stage, use a 13t double steel wheel roller to compact statically for 1 pass at a speed of 2 - 4 km / h; (2)During the compaction process, the surface of the recycled layer should always be kept moist. When the water evaporates too fast, water should be sprinkled in time to make up; (3)To avoid the mixture being pushed and bulged during compaction, the driving wheel should be facing the paver during compaction, and compact from the outside to the center. On the superelevation section, compact from low to high, and on the slope, the driving wheel should be compacted from low to high; (4) During the compaction process, when there are loose or peeling phenomena, it should be turned over and remixed in time; (5)After each section of compaction is completed and the compaction degree is checked and qualified, the in-situ recycling construction of foamed asphalt should be carried out immediately; S12. Paving of foamed asphalt cold recycling: After the in-situ cold recycling compaction of cement is completed and the compaction degree is detected and qualified, the foamed asphalt cold recycling paver is in place. The transport vehicle loaded with foamed asphalt mixture is docked with the paver, and the paver is used for paving. Determine the paving coefficient according to the type of the paver; use an aluminum alloy beam to control the thickness and flatness in the middle, and strictly control the thickness and flatness of the recycled layer; S13. Compaction of foamed asphalt cold recycling, specifically including the following steps: (1)Behind each paver, follow 1 vibrating roller for compaction. The length of one-time compaction is 100m, and then 1 single steel wheel and 1 rubber tire roller are used for compaction respectively, with distinct layers and obvious demarcation marks set; (2)Compaction must follow the principles of "first light then heavy, first slow then fast, first static then vibrating, first edge then middle, first low then high"; (3)Determine the proposed compaction combination: the front wheel of the tandem steel wheel roller is static and the rear wheel vibrates for 1 pass → the vibratory roller vibrates strongly in both the front and rear for 3 passes → the pneumatic tire roller stabilizes the pressure for 4 passes → the tandem steel wheel roller makes a static pressure for 1 pass; compact until there are no wheel marks. During the compaction process, the compaction degree shall be detected by the sand replacement method at any time. When it is unqualified, repeat the compaction until the compaction degree requirement is met through detection; after the compaction degree is detected to meet the requirements, the rolling end time of the foamed asphalt should be controlled to be completed before the initial setting time of the base cement. S14. Curing and opening to traffic: (1)When curing under the condition of closed traffic, natural curing can be carried out without taking measures. (2)When a complete core sample of the base course and surface course can be taken out by a core drill with a drill bit of Ф150mm for the regenerated layer, the curing can be ended. (3)When it is necessary to open to traffic after curing, a layer of slow-cracking emulsified asphalt shall be sprayed in a timely manner after the compaction is completed, and the spraying amount is 0.3 kg / ㎡ - 0.6 kg / ㎡.

Images