Hot in-place recycling asphalt mixture and construction method

Abstract

The invention provides a hot in-place recycling asphalt mixture and a construction method, and relates to the technical field of asphalt mixtures, and the hot in-place recycling asphalt mixture is obtained by recycling old asphalt pavement materials in a high proportion, reducing new material consumption and carbon emission, realizing resource recycling and green construction and introducing a regenerant to recover the performance of aged asphalt. The high-temperature rut resistance, the low-temperature crack resistance, the fatigue resistance and the interface bonding strength of the mixture are synergistically improved by matching with the styrene butadiene rubber modifier, the basalt fiber, the nano silicon dioxide and other functional materials, and the mixture is ensured to be uniform and free of segregation through precise feeding sequence, high-pressure atomization spraying and forced stirring parameter control. The defects of gray materials, oil balls and the like are avoided, the compactness, the flatness and the overall structure stability of the regenerated pavement are improved, and the problems of performance degradation and insufficient durability of a traditional regenerated mixture are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt mixtures, and in particular to an in-situ hot recycling asphalt mixture and a construction method thereof. Background Art

[0002] During the use of asphalt concrete, problems such as pavement aging, wear, and cracking occur, and urgent repairs and reconstructions are needed. The traditional pavement renovation method is to first dig out the old pavement and then lay a new pavement, which requires a large amount of destructive work, pollutes the environment, and wastes the recyclable resources of the old pavement. The in-situ hot recycling technology of asphalt concrete can effectively solve this problem, not only improving the pavement quality, but also increasing the proportion of reusing the old pavement, maximizing the recycling of waste mixtures, directly saving a large amount of sand, gravel, and asphalt, and effectively saving a large amount of land resources for quarrying construction sand and gravel.

[0003] The existing Chinese patent with the publication number CN117700156B discloses a recycled asphalt mixture and a preparation method thereof. The preparation method of the recycled asphalt mixture includes: heating aggregates, modified asphalt, mineral powder, and modified fibers to 150 - 160 °C; heating the modified recycled asphalt material by microwave to 140 - 150 °C, dry mixing for 1 - 2 min, then successively adding raw materials, mixing for 1 - 2 min each time after adding a raw material, then adding a warm mix agent, controlling the microwave heating temperature to 140 - 150 °C, and stirring and mixing evenly to obtain the recycled asphalt mixture. The warm mix technology reduces the construction difficulty, simultaneously reduces the construction temperature, increases the content of the old asphalt pavement, reduces the environmental pollution during construction, and alleviates the secondary aging of asphalt in the waste asphalt mixture, making the recycled asphalt mixture have a wider application prospect. However, the recycled asphalt mixture has problems such as the decline in the performance of aged asphalt, insufficient high and low temperature performance, poor durability, and weak interfacial bonding, and there are certain defects in performance during actual use.

[0004] In view of the above problems, a kind of in-situ hot recycling asphalt mixture and a construction method thereof are proposed to solve the above problems. Summary of the Invention

[0005] The technical problem to be solved by the invention is to overcome the defects existing in the prior art and propose an organic matter recovery process from ultrafiltration residue liquid, thereby solving the problems of the decline in the performance of aged asphalt, insufficient high and low temperature performance, poor durability, and weak interfacial bonding existing in the recycled asphalt mixture:

[0006] An in-situ hot recycling asphalt mixture comprises the following raw materials in parts by weight: 60-75 parts of old asphalt pavement materials, 2-5 parts of new asphalt, 1-3 parts of recycling agent, 10-20 parts of new aggregates, 2-5 parts of mineral powder, 0.3-0.6 parts of basalt fiber, 1-2 parts of styrene-butadiene rubber modifier, 1-2 parts of nano-silica, 0.2-0.5 parts of anti-stripping agent, and 0.1-0.3 parts of light stabilizer.

[0007] Further, the content of old asphalt in the old asphalt pavement materials is 3%-6%, wherein the content of coarse aggregates with a particle size greater than 4.75 mm is 40%-60%, the content of fine aggregates with a particle size less than 4.75 mm is 30%-50%, the content of mineral powder is 5%-15%, the penetration of the old asphalt is 20-60 mm under standard test conditions, and the softening point is between 40-60 °C.

[0008] Further, the penetration of the new asphalt is 60-80 mm under standard test conditions, and the softening point is not less than 46 °C.

[0009] Further, the density of the recycling agent is 0.9-1.1 g / cm 3 at 25 °C, the kinematic viscosity is 50-200 Pa·s, and the flash point is not less than 200 °C.

[0010] Further, the apparent density of the mineral powder is ≥2.5 g / cm 3 , the water content is ≤1%, and the content of particles with a particle size range less than 0.6 mm is ≥90%.

[0011] Further, the tensile strength of the basalt fiber is ≥2000 MPa, and the elastic modulus is ≥90 GPa.

[0012] Further, the particle size of the nano-silica is 10-100 nm, the specific surface area is 200-300 m 2 / g, and the silica content is ≥99%.

[0013] Further, the styrene-butadiene rubber modifier comprises the following raw materials in parts by weight: 50-75 parts of styrene-butadiene rubber, 15-25 parts of aromatic oil, 0.5-1 part of sulfur, wherein the styrene content of the styrene-butadiene rubber is 20%-30%, the flash point of the aromatic oil is ≥200 °C, the kinematic viscosity is 10-30 mm 2 / s, and the sulfur purity is ≥99%.

[0014] A construction method of an in-situ hot recycling asphalt mixture uses the in-situ hot recycling asphalt mixture as described in claims 1-8, and comprises the following steps: S1. Construction preparation and pretreatment: Dig and repair the over-deep damaged and loose diseases, mill the deformed diseases with a thickness of 30-50 mm, remove the markings, mill the periphery of the expansion joint and pre-lay new materials;

[0015] S2. Road surface heating: Uniformly heat the modified asphalt road surface to no more than 200°C, with a width on each side wider than the loosened surface by ≥200 mm. At the longitudinal joint lap, heat more than the edge line by 150 - 200 mm, and the equipment spacing of the regeneration unit ≤2 m;

[0016] S3. Monitoring of loosening and exposed surface temperature: The loosening depth is uniform, with a gradual adjustment error of ±3 mm. The loosened surface maintains roughness. After loosening, the temperature of the exposed modified asphalt surface ≥100°C;

[0017] S4. Addition and mixing of new materials: Add regenerant, new asphalt and mixture according to the mix ratio to ensure that the mixture is uniform without segregation, white and flower materials, and oil lumps;

[0018] S5. Paving operation: The paving speed is 1.5 - 4 m / min, synchronized with the heating equipment. Use a double screed board. The paving temperature of the modified asphalt mixture ≥130°C, and the screed board preheating ≥110°C;

[0019] S6. Compaction: Compaction closely follows the paver. The double steel wheel roller reduces water spraying, and the rubber tire roller does not spray water. For areas such as corners where large machines cannot compact, use a small vibratory roller or a vibrating rammer for supplementary compaction;

[0020] S7. Natural curing: Close the traffic after compaction until the road surface temperature ≤50°C;

[0021] S8. Quality inspection during construction: Check the regenerant, new material gradation, and asphalt content daily. Real-time monitor and control the deviation of the regeneration thickness within the range of -1 mm to +5 mm, ensure that the construction width is not less than the design value, and synchronously detect the compaction degree.

[0022] Furthermore, S4 includes the following steps:

[0023] S41. When adding regenerant, new asphalt and mixture according to the mix ratio, first use an automated metering system to calibrate the addition amounts of regenerant, new asphalt and new aggregates. For the regenerant, use a high-pressure atomizing spraying device to spray at a pressure of 0.4 - 0.6 MPa, keep the nozzle 30 - 50 cm away from the loosened material surface, so that the regenerant evenly covers the old material, forming a fan-shaped mist surface, and the coverage width error is within ±10 cm. Heat the new asphalt to 165 - 175°C, transport it through a heat transfer oil insulation pipeline, and dynamically regulate the flow rate of the new asphalt according to the mix ratio with the help of a gear pump. And record the pressure and flow rate data every 10 minutes to ensure that the addition amount is consistent with the designed usage amount;

[0024] S42. Feed materials in the order of "reclaimed materials - rejuvenator - new aggregates - mineral powder - modified asphalt", and then start the twin-shaft forced mixer to carry out staged mixing work. First is the premixing stage. First, mix the reclaimed materials at a low speed of 300 - 400 r / min for 3 - 5 s, then spray in the rejuvenator and continue mixing for 6 - 8 s to promote the full penetration of the rejuvenator into the aged asphalt. Then enter the gradation adjustment stage, add new aggregates and mineral powder, increase the mixing speed to 500 - 600 r / min, and mix for 8 - 10 s to initially mix the materials evenly. Then reach the modified fusion stage, put in materials such as styrene-butadiene rubber modifier, basalt fiber, and nano-silica, and mix at a high speed of 700 - 800 r / min for 10 - 15 s to fully disperse the modified materials. Finally is the cementing and coating stage, add new modified asphalt, anti-stripping agent, and light stabilizer, and carry out wet mixing at a rotation speed of 800 - 1000 r / min for 30 - 35 s. At the same time, monitor the discharge temperature in real time to ensure it is within the range of 160 - 175 °C to ensure that the aggregates can be completely coated by the asphalt mortar;

[0025] S43. During preparation, a special person monitors the discharge of each batch through the visualization window, records the color and uniformity, takes samples at multiple places to check for oil clusters and mottled materials. If segregation or mottled materials are found, extend the mixing time and remix twice. If the pipeline is blocked resulting in oil clusters, use high-pressure air to dredge it. After detecting that the residual asphalt meets the standards, carry out construction.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] A hot in-place recycling asphalt mixture and construction method proposed by the present invention, in terms of material composition, by highly recycling old asphalt pavement materials, significantly reduces the consumption of new materials and carbon emissions, realizes resource recycling and green construction; introduces a rejuvenator to restore the performance of aged asphalt, and is combined with functional materials such as styrene-butadiene rubber modifier, basalt fiber, and nano-silica to synergistically improve the high-temperature rutting resistance, low-temperature crack resistance, fatigue resistance, and interface bonding strength of the mixture, solving the problems of performance decline and insufficient durability of traditional recycled mixtures.

[0028] In terms of construction technology, through precise feeding sequence, high-pressure atomization spraying, and forced mixing parameter control, it ensures that the mixture is uniform without segregation, avoiding defects such as mottled materials and oil clusters; combined with real-time temperature monitoring, gradation screening, and quality dynamic adjustment mechanism, it realizes the refined control of the construction process, significantly improves the compaction degree, flatness, and overall structural stability of the recycled pavement, is suitable for efficient recycling and repair under complex climate conditions, and extends the service life of the pavement. Brief Description of the Drawings

[0029] The disclosure of the present invention will be described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them:

[0030] Figure 1 Schematically shows a flow chart of the construction method of in-situ hot recycled asphalt mixture proposed according to an embodiment of the present invention. Detailed implementation manners

[0031] It is easily understood that according to the technical solution of the present invention, without changing the essence of the present invention, those of ordinary skill in the art can propose various interchangeable structural ways and implementation manners. Therefore, the following detailed implementation manners and the accompanying drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as all of the present invention or as a limitation or restriction on the technical solution of the present invention.

[0032] Example 1

[0033] According to an embodiment of the present invention, an in-situ hot recycled asphalt mixture, the raw materials of the in-situ hot recycled asphalt mixture include: 68 parts of old asphalt pavement materials, 3.5 parts of new asphalt, 2 parts of regenerant, 15 parts of new aggregates, 3.5 parts of mineral powder, 0.45 parts of basalt fiber, 1.5 parts of styrene-butadiene rubber modifier, 1.5 parts of nano-silica, 0.35 parts of anti-stripping agent, 0.2 parts of light stabilizer. Through the corresponding ratio, the dual effects of performance improvement and resource recycling are achieved. The use of a high proportion of old asphalt pavement materials significantly improves the recycling rate of waste materials, meeting the requirements of green environmental protection and low-carbon construction. The new asphalt and regenerant can restore the performance of aged asphalt and reconstruct the viscosity and flexibility of the cementing system. The new aggregates and mineral powder optimize the gradation and enhance the skeleton support structure of the mixture. The basalt fiber and styrene-butadiene rubber modifier act synergistically to improve the tensile strength, anti-fatigue cracking ability and deformation coordination of the material. The nano-silica and anti-stripping agent improve the interfacial bonding performance and enhance the anti-water damage and wear resistance characteristics. The light stabilizer effectively resists ultraviolet aging and delays the performance decay. The overall formula takes into account both economy and road performance, making the recycled mixture have excellent mechanical strength, durability and anti-aging ability, suitable for in-situ hot recycling repair of asphalt pavements, and realizing the efficient utilization of waste materials and the sustainable improvement of pavement performance.

[0034] The content of old asphalt in the old asphalt pavement material is between 3% and 6%. Among them, the content of coarse aggregate with a particle size greater than 4.75 mm is 40%-60%, the content of fine aggregate with a particle size less than 4.75 mm is 30%-50%, the content of mineral powder is 5%-15%, and the penetration of the old asphalt is between 20 and 60 mm under standard test conditions. Penetration time: 5 s, softening point is between 40 and 60 °C. The standard test conditions are: test temperature: 25 °C, standard needle mass: 100 g. The index limits of the old asphalt pavement material lay the foundation for the performance of the recycled mixture by precisely controlling the component composition and the performance of the old asphalt. The old asphalt content of 3%-6% ensures the efficient utilization of waste materials while avoiding insufficient bonding ability caused by excessive asphalt aging or unbalanced content. The grading design of 40%-60% of coarse aggregate with a particle size greater than 4.75 mm and 30%-50% of fine aggregate with a particle size less than 4.75 mm forms a framework dense structure, improving the compressive strength and deformation resistance of the mixture. The coordinated ratio of coarse and fine aggregates can reduce the void ratio and enhance the overall stability. The mineral powder content of 5%-15% acts as a filling inert component, optimizing the viscosity of the slurry, improving the bonding effect between aggregates, and enhancing the fatigue cracking resistance. The penetration of the old asphalt is 20-60 mm and the softening point is 40-60 °C at 25 °C, indicating that it retains certain viscoelasticity and temperature stability, facilitating the penetration and fusion of the rejuvenator, restoring the asphalt colloid structure, and avoiding insufficient toughness or poor high-temperature stability of the binder after regeneration due to excessive aging.

[0035] The penetration of the new asphalt is between 60 and 80 mm under standard test conditions, the softening point ≥ 46 °C, the rejuvenator has good fluidity, compatibility and anti-aging performance. Its density at 25 °C is: 0.9-1.1 g / cm 3 , and the kinematic viscosity at 60 °C is: 50-200 Pa·s, flash point: ≥ 200 °C. The penetration and softening point ensure that it has appropriate viscosity and high-temperature stability. When compounded with the old asphalt, it can optimize the viscoelasticity of the binder, improve the low-temperature cracking resistance and high-temperature rutting resistance of the mixture. The good fluidity of the rejuvenator promotes the penetration and softening of the aged asphalt, the compatibility ensures the uniform fusion of new and old components, and the anti-aging performance delays the aging process of the recycled asphalt. The two work together to restore the performance of the old asphalt, enhancing the overall durability and road performance of the recycled mixture.

[0036] The apparent density of the mineral powder ≥ 2.5 g / cm 3 , the water content ≤ 1%, the particle content with a particle size range less than 0.6 mm ≥ 90%, the tensile strength of basalt fiber ≥ 2000 MPa, the elastic modulus ≥ 90 GPa, the particle size of nano-silica: 10-100 nm, specific surface area: 200-300 m 2 / g, with a silica content of ≥99%. The apparent density of the mineral powder and low water content ensure its compactness and dry state, avoiding moisture interference with the bonding effect of the binder. A particle size <0.6mm accounting for ≥90% allows it to fully fill the aggregate gaps, optimizing the viscosity of the mastic and the interfacial bonding force, enhancing the compactness of the mixture and its resistance to fatigue cracking. The high tensile strength and elastic modulus of basalt fiber can effectively bear the load and disperse stress, improving the tensile strength and deformation resistance of the mixture, inhibiting crack propagation, and enhancing toughness and durability. By uniformly dispersing nano-silica in the asphalt system, the bonding strength and toughness of the binder are significantly enhanced, filling micro-pores and improving interfacial compatibility, increasing the compactness of the mixture and its resistance to water damage. High purity ensures its chemical stability, synergistically enhancing anti-aging and abrasion resistance performance, and optimizing the mechanical strength and durability of the asphalt mixture.

[0037] The styrene-butadiene rubber modifier comprises the following raw materials in parts by weight: 50 - 75 parts of styrene-butadiene rubber, 15 - 25 parts of aromatic oil, and 0.5 - 1 part of sulfur. Among them, the styrene content of the styrene-butadiene rubber is between 20% - 30%, the flash point of the aromatic oil is ≥200°C, and the kinematic viscosity is 10 - 30mm 2 / s, with sulfur purity ≥99%. Styrene-butadiene rubber combines rubber elasticity and resin compatibility, improving the flexibility of asphalt, its resistance to fatigue cracking, and low-temperature anti-brittle cracking performance. Aromatic oil, as a softening and plasticizing component, improves the compatibility between rubber and asphalt and processing fluidity, enhancing the flexibility of the system. High-purity sulfur promotes the vulcanization cross-linking reaction between rubber and asphalt, forming a stable network structure, improving the bonding strength between the modifier and asphalt and its high-temperature stability. The synergistic effect of the three makes the modified asphalt mixture possess excellent elastic recovery ability, deformation resistance, and weather resistance, effectively dealing with pavement fatigue, cracking, etc. under heavy traffic and complex environments.

[0038] In this embodiment, the proportion of old asphalt pavement materials is 68%, with a high resource recycling rate and the cost reduced by about 30% compared to brand-new mixtures. After the new asphalt and the rejuvenator are compounded, the softening point of the old asphalt is increased by 15% - 20%, the ductility at 15°C is restored to more than 90% of the original asphalt, and the bonding force is enhanced by 25%. The new aggregates and mineral powder make the Marshall stability reach 12 - 15kN and the flow value 2 - 3mm, with the overall structural strength increased by 20%. 0.45% basalt fiber increases the splitting strength by 18% and the crack resistance by 30%. 1.5% styrene-butadiene rubber modifier makes the low-temperature ductility at -10°C reach more than 30cm, the elastic recovery rate ≥85%, and the anti-aging performance is improved by 40%. 1.5% nano-silica increases the high-temperature dynamic stability to more than 8000 times / mm, and 0.35% anti-stripping agent makes the adhesion grade of aggregates and asphalt reach grade 5 by the boiling water method, effectively reducing water stripping. 0.2% light stabilizer makes the performance retention rate ≥85% after 500 hours of ultraviolet aging, significantly extending the service life of the pavement, and the comprehensive performance meets the technical standards for the regeneration of heavy traffic pavement.

[0039] Table 1 is the parameter test table of Example 1

[0040]

[0041]

[0042] Table 1

[0043] Example Two

[0044] The difference between this example and Example 1 is that no styrene-butadiene rubber is added.

[0045] Comparison result: The rutting dynamic stability drops to 4,500 times / mm, and it is prone to bleeding and deformation at high temperature; the low-temperature bending failure strain is 2,200 με, and cracking occurs at -20 °C.

[0046] Reason: The styrene-butadiene rubber elastic network is missing, the high-temperature viscosity of the asphalt mortar is insufficient, and the brittleness of the asphalt film increases at low temperature, making it unable to effectively dissipate temperature stress.

[0047] Example Three

[0048] The difference between this example and Example 1 is that no basalt fiber is added. The lack of fiber leads to a decrease in crack resistance, and the mineral powder is increased to 4.0 parts to enhance compactness.

[0049] Comparison result: The number of fatigue test cycles drops from 100,000 times to 60,000 times, and the propagation of microcracks accelerates; the Marshall stability drops to 10.2 kN, and the compressive strength decreases.

[0050] Reason: The "reinforcement effect" of basalt fiber is missing, the load transfer efficiency between aggregates drops, and cracks are prone to initiate in stress concentration areas.

[0051] Example Four

[0052] The difference between this example and Example 1 is that no nano-silica is added. The nano-filler is missing, and the mineral powder is increased to 4.5 parts to compensate for the interfacial bonding.

[0053] Comparison result: The asphalt film peeling rate after thin film oven reaches 12%, and the water permeability coefficient rises to 180 ml / min; the specific surface area of the mortar decreases by 30%, and the interfacial bonding force between asphalt and filler drops.

[0054] Reason: The "nano-effect" of nano-silica is missing, a dense mortar structure cannot be formed, moisture is easy to invade the aggregate-asphalt interface, and peeling is accelerated.

[0055] Example Five

[0056] The difference between this example and Example 1 is that no regenerant is added. New asphalt is additionally supplemented to 6.0 parts to maintain the total amount of binder, and new aggregates are increased to 18 parts to improve the skeleton structure.

[0057] Comparison result: The penetration of the old asphalt is only 35, the softening point rises to 65 °C, and the aging is serious; the viscosity ratio of the recycled mixture reaches 4.5. The viscosity ratio of this recycled mixture is more than 3 times the standard value, and the brittleness of the asphalt increases.

[0058] Reason: The aromatic components missing in the aged asphalt are not replenished, and the light components of the old asphalt are insufficient, resulting in the decline of the performance of the binder.

[0059] Example VI

[0060] The difference between this example and Example I is that no anti-stripping agent is added, and the mineral powder is increased to 5.0 parts.

[0061] Comparison result: The stripping rate by the boiling water method reaches 15%, and the freeze-thaw splitting strength ratio drops to 70%; the adhesion of acidic aggregates decreases significantly.

[0062] Reason: The anti-stripping agent is missing, unable to neutralize the acidic groups on the surface of the aggregates, the chemical adsorption force between the asphalt and the aggregates weakens, and the risk of water damage increases.

[0063] Table 2 is a parameter comparison table of Example 1 and Examples 2-6

[0064]

[0065] Table 2

[0066] Another technical solution provided by the present invention is a construction method for in-situ hot recycled asphalt mixture, including the following steps: S1. Construction preparation and pretreatment: Dig and repair the super-deep damaged and loose diseases, mill the deformed diseases with a depth of 30-50 mm, remove the markings, mill the periphery of the expansion joint and pre-lay new materials;

[0067] S2. Pavement heating: Uniformly heat the modified asphalt pavement to no more than 200 °C, the width on each side is ≥ 200 mm wider than the loosened surface, the heating at the longitudinal joint lap exceeds the side line by 150-200 mm, and the equipment spacing of the recycling unit is ≤ 2 m;

[0068] S3. Loosening and monitoring of the exposed surface temperature: The loosening depth is uniform, the gradient adjustment error is ±3 mm, the loosened surface maintains roughness, and after loosening, the temperature of the exposed surface of the modified asphalt is ≥ 100 °C;

[0069] S4. Addition and mixing of new materials: Add regenerant, new asphalt and mixture according to the mix ratio to ensure that the mixture is uniform without segregation, white and flower materials, and oil lumps;

[0070] S5. Paving operation: The paving speed is 1.5-4 m / min, synchronized with the heating equipment, double screeds are used, the paving temperature of the modified asphalt mixture is ≥ 130 °C, and the screed is preheated ≥ 110 °C;

[0071] S6, Roller Compaction: Compaction follows closely behind the paver. For the tandem steel wheel roller, reduce the water spraying, and for the pneumatic tired roller, do not spray water. For areas such as corners that cannot be compacted by large machines, use a small vibratory roller or a vibrating rammer for supplementary compaction;

[0072] S7, Natural Curing: After compaction, close the traffic until the pavement temperature ≤ 50°C;

[0073] S8, Quality Inspection during Construction Process: Check the rejuvenator, new aggregate gradation, and asphalt content daily. Real-time monitor and control the deviation of the regeneration thickness within the range of -1 mm to +5 mm, ensure that the construction width is not less than the design value, and synchronously detect the compaction degree.

[0074] S4 includes the following steps:

[0075] S41, When adding the rejuvenator, new asphalt, and mixture according to the mix ratio, first use an automated metering system to calibrate the addition amounts of the rejuvenator, new asphalt, and new aggregates. For the rejuvenator, use a high-pressure atomizing spraying device to spray at a pressure of 0.4 - 0.6 MPa, keep the nozzle 30 - 50 cm away from the loosened material surface, so that the rejuvenator evenly covers the old material, forming a fan-shaped mist surface, and the coverage width error is within ±10 cm. Heat the new asphalt to 165 - 175°C, transport it through a heat-conducting oil insulation pipeline, and use a gear pump to dynamically adjust the flow rate of the new asphalt according to the mix ratio, and record the pressure and flow rate data every 10 minutes to ensure that the addition amount is consistent with the designed dosage;

[0076] S42, Load materials in the order of "old material - rejuvenator - new aggregate - mineral powder - modified asphalt", and then start the twin-shaft forced mixer to carry out staged mixing work. First is the premixing stage, first stir the old material at a low speed of 300 - 400 r / min for 3 - 5 s, then spray in the rejuvenator and continue stirring for 6 - 8 s to promote the full penetration of the rejuvenator into the aged asphalt. Then enter the gradation adjustment stage, add the new aggregate and mineral powder, increase the stirring speed to 500 - 600 r / min, and stir for 8 - 10 s to make the materials preliminarily mixed evenly. Then to the modification fusion stage, put in materials such as styrene-butadiene rubber modifier, basalt fiber, and nano-silica, stir at a high speed of 700 - 800 r / min for 10 - 15 s to fully disperse the modified materials. Finally is the cementing and coating stage, add the new modified asphalt, anti-stripping agent, and light stabilizer, and carry out wet mixing at a rotation speed of 800 - 1000 r / min for 30 - 35 s, while real-time monitoring the discharge temperature to ensure that it is within the range of 160 - 175°C to ensure that the aggregates can be completely coated with the asphalt mortar;

[0077] S43. During preparation, a dedicated person monitors the discharge of each batch through a visualization window, records the color and uniformity, takes samples at multiple locations to check for oil lumps and variegated materials. If segregation or variegated materials are found, extend the mixing time and remix twice. If the pipeline is blocked and causes oil lumps, use high-pressure air to unclog it. After the residual asphalt passes the inspection, start the construction.

[0078] In this embodiment, through the refined control of the whole process, this construction method systematically solves the problems in traditional in-situ hot recycling, such as incomplete treatment of diseases, uneven mixing of materials, deviation in temperature control, and insufficient compaction quality: During the construction preparation stage, targeted treatment is carried out on ultra-deep damage, deformation diseases, and expansion joints to eliminate structural hidden dangers; during the heating and loosening link, through width control, coordination of equipment spacing, and temperature monitoring, ensure that the old materials are evenly softened; for the addition and mixing of new materials, high-pressure atomization spraying, sequential feeding, and multi-stage mixing parameter control are adopted to achieve precise dispersion of the regenerant and modified materials, and avoid segregation and variegated materials; during the paving and compaction link, through the double screed process, compaction equipment combination, and corner supplementary compaction, ensure the flatness and compaction degree; the curing and quality inspection form a "construction - detection - adjustment" closed loop, and monitor indicators such as gradation, thickness, and compaction degree in real time. Finally, while achieving high recycling of old materials, significantly improve the uniformity, structural stability, and long-term durability of the recycled road surface, providing a reliable guarantee for the recycling construction of high-grade highways.

[0079] The technical scope of the present invention is not limited to the content described above. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. An in-situ hot recycling asphalt mixture, characterized in that, It comprises the following raw materials in parts by weight: 60 - 75 parts of old asphalt pavement materials, 2 - 5 parts of new asphalt, 1 - 3 parts of regenerant, 10 - 20 parts of new aggregate, 2 - 5 parts of mineral powder, 0.3 - 0.6 parts of basalt fiber, 1 - 2 parts of styrene-butadiene rubber modifier, 1 - 2 parts of nano-silica, 0.2 - 0.5 parts of anti-stripping agent, and 0.1 - 0.3 parts of light stabilizer.

2. The in-situ hot recycling asphalt mixture according to claim 1, wherein The content of old asphalt in the old asphalt pavement materials is 3% - 6%. Among them, the content of coarse aggregate with a particle size greater than 4.75 mm is 40% - 60%, the content of fine aggregate with a particle size less than 4.75 mm is 30% - 50%, the content of mineral powder is 5% - 15%, the penetration of the old asphalt is 20 - 60 mm under standard test conditions, and the softening point is between 40 - 60 °C.

3. The in-situ hot recycling asphalt mixture according to claim 1, wherein The penetration of the new asphalt is 60 - 80 mm under standard test conditions, and the softening point is not less than 46 °C.

4. The in-situ hot recycling asphalt mixture according to claim 1, characterized in that, The density of the regenerant is 0.9 - 1.1 g / cm at 25°C 3 , kinematic viscosity: 50 - 200 Pa·s, flash point not less than 200°C.

5. The in-situ hot recycling asphalt mixture according to claim 1, wherein The apparent density of the mineral powder is ≥ 2.5 g / cm 3 , the water content is ≤ 1%, and the content of particles with a particle size range less than 0.6 mm is ≥ 90%.

6. The in-situ hot recycling asphalt mixture according to claim 1, characterized in that, The tensile strength of the basalt fiber is ≥2000 MPa, and the elastic modulus is ≥90 GPa.

7. The in-situ hot recycling asphalt mixture according to claim 1, wherein The particle size of the nano-silica is 10 - 100 nm, the specific surface area is 200 - 300 m 2 / g, and the silica content is ≥99%.

8. The in-situ hot recycling asphalt mixture according to claim 1, characterized in that The styrene-butadiene rubber modifier comprises the following raw materials in parts by weight: 50-75 parts of styrene-butadiene rubber, 15-25 parts of aromatic oil, and 0.5-1 part of sulfur, wherein the styrene content of the styrene-butadiene rubber is 20%-30%, the flash point of the aromatic oil is ≥200°C, the kinematic viscosity is 10-30 mm 2 / s, and the sulfur purity is ≥99%.

9. A construction method for in-situ hot recycled asphalt mixture, which uses the in-situ hot recycled asphalt mixture as described in claims 1-8, and is characterized in that, It includes the following steps: S1. Construction preparation and pretreatment: Repair the super-deep damaged and loose diseases by patching, mill the deformed diseases with a depth of 30 - 50 mm, remove the markings, mill the periphery of the expansion joint and pre-lay new materials; S2. Pavement heating: Uniformly heat the modified asphalt pavement to no more than 200 °C, the width on each side is ≥200 mm wider than the loosened surface, the heating at the longitudinal joint overlap exceeds the side line by 150 - 200 mm, and the equipment spacing of the regeneration unit is ≤2 m; S3. Loosening and monitoring of the exposed surface temperature: The loosening depth is uniform, the gradual adjustment error is ±3 mm, the loosened surface maintains roughness, and after loosening, the temperature of the exposed surface of the modified asphalt is ≥100 °C; S4. Addition and mixing of new materials: Add regenerant, new asphalt and mixture according to the mix ratio to ensure that the mixture is uniform without segregation, white and flower materials, and oil lumps; S5. Paving operation: The paving speed is 1.5 - 4 m / min, synchronized with the heating equipment, using a double screed, the paving temperature of the modified asphalt mixture is ≥130 °C, and the screed is preheated to ≥110 °C; S6. Rolling and compaction: Compaction follows the paver closely. The double-drum roller reduces water spraying, and the rubber-tired roller does not spray water. For areas such as corners where large machines cannot compact, a small vibrating roller or vibrating rammer is used for supplementary compaction; S7. Natural curing: After compaction, traffic is closed until the pavement temperature ≤50 °C; S8. Quality inspection during construction: Check the regenerant, new material gradation, and asphalt content daily, monitor and control the deviation of the regeneration thickness in the range of -1 mm to +5 mm in real time to ensure that the construction width is not less than the design value, and synchronously detect the compaction degree.

10. The construction method of the in-situ hot recycling asphalt mixture according to claim 9, characterized in that, The said S4 includes the following steps: S41. When adding the regenerant, new asphalt and mixture according to the mix ratio, first use an automated metering system to calibrate the addition amounts of the regenerant, new asphalt and new aggregates. For the regenerant, use a high-pressure atomizing spraying device to spray at a pressure of 0.4 - 0.6 MPa, keep the nozzle 30 - 50 cm away from the loosened material surface, so that the regenerant evenly covers the old material, forming a fan-shaped mist surface, and the coverage width error is within ±10 cm. Heat the new asphalt to 165 - 175 °C, transport it through a heat-conducting oil insulation pipeline, dynamically regulate the flow rate of the new asphalt according to the mix ratio with the help of a gear pump, and record the pressure and flow rate data every 10 minutes to ensure that the addition amount is consistent with the designed dosage; S42. Feed the materials in the order of "old material - regenerant - new aggregates - mineral powder - modified asphalt", and then start the double-shaft forced mixer to carry out staged mixing work. First is the premixing stage. First, stir the old material at a low speed of 300 - 400 r / min for 3 - 5 s, then spray in the regenerant and continue stirring for 6 - 8 s to promote the full penetration of the regenerant into the aged asphalt. Then enter the grading adjustment stage, add new aggregates and mineral powder, increase the stirring speed to 500 - 600 r / min, and stir for 8 - 10 s to preliminarily mix the materials evenly. Then to the modification and fusion stage, put in materials such as styrene-butadiene rubber modifier, basalt fiber, and nano-silica, stir at a high speed of 700 - 800 r / min for 10 - 15 s to fully disperse the modified materials. Finally is the cementation and coating stage, add new modified asphalt, anti-stripping agent and light stabilizer, and carry out wet mixing at a rotation speed of 800 - 1000 r / min for 30 - 35 s, while monitoring the discharge temperature in real time to ensure that it is within the range of 160 - 175 °C to ensure that the aggregates can be completely coated by the asphalt mortar; S43. During the preparation, a special person monitors the discharge of each batch through a visualization window, records the color and uniformity, takes samples at multiple places to check for oil lumps and variegated materials. If segregation or variegated materials are found, extend the mixing time and remix twice. If the pipeline is blocked resulting in oil lumps, use high-pressure air to dredge it. After detecting that the residual asphalt meets the standards, proceed with the construction.

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