Micro-amount of new asphalt based full-rap cold recycled asphalt mixture and preparation method thereof

Abstract

The application discloses a kind of based on trace new asphalt full RAP cold regeneration asphalt mixture and preparation method, the content of each substance in the cold regeneration asphalt mixture is asphalt pavement recycling material 96-97wt%, dilution asphalt 0.8-1wt%, old material activator 1.5-2wt%, mineral powder 0.5-1wt%, diluent and old material activator contain D40 de-aromatic solvent oil and D60 de-aromatic solvent oil.The preparation method includes the following steps: preparation dilution asphalt and old material activator;Rich oil and lean oil asphalt pavement recycling material, mineral powder are placed in oven and dried;First, rich oil and lean oil asphalt pavement recycling material are respectively mixed with old material activator, then mixed with dilution asphalt, mineral powder.The cold regeneration asphalt mixture prepared by the application has excellent comprehensive performance, and at the same time realizes the maximization of RAP material regeneration ratio and the trace control of new asphalt.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of asphalt pavement materials and preparation, and particularly relates to a full-RAP cold recycled asphalt mixture based on trace new asphalt and a preparation method. BACKGROUND

[0002] At present, the highway mileage in China has reached millions of kilometers, of which more than 90% of the expressways are asphalt pavements. With the increasing service life of asphalt pavements, many asphalt pavements have reached the design period, and a large amount of asphalt pavements need to be repaired, reconstructed and maintained every year, thereby generating a large amount of reclaimed asphalt pavement (RAP). Regeneration and utilization of the reclaimed asphalt pavement RAP by mixing it into new asphalt mixture to repave the pavement is an effective way to realize the resource utilization of solid waste. This technology not only effectively solves the problems of waste material stacking and environmental pollution, but also releases the residual value of old materials, reduces the demand for natural resources such as stone and asphalt, and simultaneously realizes carbon emission reduction benefits.

[0003] Under the combined action of long-term driving load and environmental factors, the aggregate particles of the asphalt pavement will produce fatigue damage, and will be affected by milling, crushing and storage processes, thereby causing the reclaimed asphalt pavement RAP to have more fine aggregate components, i.e., to exhibit fine aggregate enrichment characteristics. It is worth noting that due to the bonding effect of aged asphalt, there are a large number of false particle groups in the reclaimed asphalt pavement RAP, forming a mixture of virtual and real particle agglomerates. The false particle groups will be structurally broken during the compaction of the asphalt mixture, directly changing the design gradation of the asphalt mixture.

[0004] The cold recycling technology of RAP materials is the mainstream technology for highway paving, reconstruction and maintenance, and the cold recycling technology mainly includes emulsified asphalt cold recycling and foamed asphalt cold recycling. The emulsified asphalt cold recycling is to disperse high-temperature asphalt into an oil-in-water emulsion through an emulsifier, and the emulsion can be mixed with aggregate at room temperature during construction. After the water evaporates, the asphalt particles re-agglomerate and break, forming a continuous asphalt film to bond the aggregate. The foamed asphalt cold recycling is to inject water into hot asphalt at 150-180℃, and the water instantaneously vaporizes to make the asphalt volume expand, forming a foam structure and mixing with the aggregate. After the foam breaks, the asphalt wraps the aggregate in the form of droplets, but the foamed asphalt is discontinuously distributed on the surface of the aggregate, having the characteristics of spot welding.

[0005] The existing research finds that the RAP material regeneration ratio and application layer can be improved by pretreating the RAP material, adding an external additive, and optimizing the construction process, but there are still some technical problems: (1) Although the application layer can be improved to the pavement surface layer (lower layer, middle layer, and upper layer), the RAP material regeneration ratio is usually not more than 50%, and the maximization of the RAP material regeneration ratio cannot be realized; (2) The amount of new asphalt is still large, and whether it is applied to the base layer or the surface layer, the trace addition of new asphalt (usually the addition amount of new asphalt is not more than 1% of the regenerated asphalt mixture is regarded as trace addition) cannot be realized; (3) The new and old asphalt cannot be fully fused, which will limit the overall performance of the asphalt mixture. Therefore, it is urgent to develop a full-RAP cold recycled asphalt mixture based on trace new asphalt and a preparation method to solve the problems existing in the prior art. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a full-RAP cold recycled asphalt mixture based on trace new asphalt, wherein the mass percentage of each substance in the cold recycled asphalt mixture is 96-97wt% of asphalt pavement recycling material, 0.8-1wt% of dilution asphalt, 1.5-2wt% of old material activator, and 0.5-1wt% of mineral powder; the mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil is used as a diluent in the dilution asphalt, and the old material activator contains D40 de-aromatic solvent oil and D60 de-aromatic solvent oil.

[0007] Preferably, the asphalt pavement recycling material is composed of asphalt pavement recycling material in a rich oil state and asphalt pavement recycling material in a lean oil state, and the mass percentage of the asphalt pavement recycling material in a rich oil state and the asphalt pavement recycling material in a lean oil state in the asphalt pavement recycling material is both 50%.

[0008] Preferably in any of the above schemes, the asphalt pavement recycling material in a rich oil state includes two grades of particle size, 3-5mm and 0-3mm, and the mass percentage of each grade of particle size in the asphalt pavement recycling material in a rich oil state is 70-80wt% of particle size 3-5mm and 20-30wt% of particle size 0-3mm.

[0009] In any of the above solutions, it is preferred that the lean oil state asphalt pavement recycling material includes five particle size ranges, 19-21.5 mm, 16-19 mm, 13.2-16 mm, 9.5-13.2 mm, and 4.75-9.5 mm, and the mass percentage of each particle size range in the lean oil state asphalt pavement recycling material is 5-8 wt% for the 19-21.5 mm particle size range, 12-18 wt% for the 16-19 mm particle size range, 6-10 wt% for the 13.2-16 mm particle size range, 17-23 wt% for the 9.5-13.2 mm particle size range, and 48-52 wt% for the 4.75-9.5 mm particle size range.

[0010] In any of the above solutions, it is preferred that the mass percentage of each substance in the dilution asphalt is 65-70 wt% for the base asphalt, 2-4 wt% for the SBS modifier, 0.2-0.5 wt% for the anti-stripping agent, 25-28 wt% for the diluent, and 2-3 wt% for the aromatic oil; the diluent is a mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil, and the mass percentage of each substance in the diluent is 30-50 wt% for the D40 de-aromatic solvent oil and 50-70 wt% for the D60 de-aromatic solvent oil.

[0011] In any of the above solutions, it is preferred that the base asphalt is No. 70 base asphalt; the SBS modifier is linear SBS modifier; and the anti-stripping agent is a non-amine anti-stripping agent, which is any one or several of polyphosphoric acid, phosphate ester, and nitrogen-containing complex.

[0012] The D40 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatization and hydrorefining and then fractionation, using straight-run distillate oil, hydrocracking distillate oil, or low-sulfur straight-run aviation kerosene as raw material, with a distillation range of 150-200℃, a closed flash point of 40-50℃, an aromatic content of less than 0.03 wt%, a sulfur content of less than 0.2 mg / kg, and a saturated hydrocarbon content of more than 99.9%.

[0013] The D60 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatization and hydrorefining and then fractionation, using straight-run distillate oil, hydrocracking distillate oil, or low-sulfur straight-run aviation kerosene as raw material, with a distillation range of 180-230℃, a closed flash point of 60-70℃, an aromatic content of less than 0.03 wt%, a sulfur content of less than 0.2 mg / kg, and a saturated hydrocarbon content of more than 99.9%.

[0014] The flash point of the aromatic oil is not less than 200℃, the density is 0.99-1.02 g / cm 3 , and the kinematic viscosity at 100℃ is 15-22 mm 2 / s.

[0015] Preferably in any of the above solutions, the mass percentage of each substance in the old material activator is 40-45wt% of D40 de-aromatic solvent oil, 40-45wt% of D60 de-aromatic solvent oil, and 10-20wt% of aromatic oil.

[0016] Preferably in any of the above solutions, the D40 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatic hydrogenation refining and fractionation from straight-run fraction oil, hydrocracking fraction oil or low-sulfur straight-run aviation kerosene, with a distillation range of 150-200℃, a closed flash point of 40-50℃, an aromatic content of less than 0.03wt%, a sulfur content of less than 0.2mg / kg, and a saturated hydrocarbon content of more than 99.9%.

[0017] The D60 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatic hydrogenation refining and fractionation from straight-run fraction oil, hydrocracking fraction oil or low-sulfur straight-run aviation kerosene, with a distillation range of 180-230℃, a closed flash point of 60-70℃, an aromatic content of less than 0.03wt%, a sulfur content of less than 0.2mg / kg, and a saturated hydrocarbon content of more than 99.9%.

[0018] The flash point of the aromatic oil is not less than 200℃, the density is 0.99-1.02g / cm 3 , and the kinematic viscosity at 100℃ is 15-22mm 2 / s.

[0019] The present application also provides a preparation method of the full-RAP cold recycled asphalt mixture based on trace new asphalt, for preparing the full-RAP cold recycled asphalt mixture based on trace new asphalt as described in any of the above solutions, which comprises the following steps in the order:

[0020] Step one: prepare the dilution asphalt according to the designed material ratio and process parameters, and store it at room temperature for standby;

[0021] Step two: mix the D40 de-aromatic solvent oil, the D60 de-aromatic solvent oil and the aromatic oil according to the designed material ratio, to obtain the old material activator, and store it at room temperature for standby;

[0022] Step three: put the asphalt pavement recycling materials in rich-oil state of each size range, the asphalt pavement recycling materials in lean-oil state of each size range, and the mineral powder into the oven respectively for drying treatment, and after the drying treatment is completed, take out the asphalt pavement recycling materials in rich-oil state of each size range, the asphalt pavement recycling materials in lean-oil state of each size range, and the mineral powder from the oven respectively, and cool them to room temperature naturally for standby;

[0023] Step four: put the asphalt pavement recycling materials of each grade particle size in rich oil state into the first mixing pot and stir using the stirrer; put the asphalt pavement recycling materials of each grade particle size in poor oil state into the second mixing pot and stir using the stirrer;

[0024] Step five: add part of the old material activator into the first mixing pot and continue to stir using the stirrer; add the remaining old material activator into the second mixing pot and continue to stir using the stirrer; after the stirring is completed, transfer all the materials in the second mixing pot into the first mixing pot;

[0025] Step six: add the dilution asphalt into the first mixing pot and continue to stir using the stirrer;

[0026] Step seven: add the mineral powder into the first mixing pot and continue to stir using the stirrer; after the stirring is completed, the micro-new-asphalt-based full RAP cold recycled asphalt mixture can be prepared.

[0027] Preferably, in step one, the preparation method of the dilution asphalt comprises the following steps in the order:

[0028] Step (1): weigh the base asphalt, SBS modifier, anti-stripping agent, D40 de-aromatic solvent oil, D60 de-aromatic solvent oil, and aromatic oil according to the designed material ratio;

[0029] Step (2): put the base asphalt into a container, then put the container containing the base asphalt into an oven for heating, the heating temperature is 100-120℃, and the heating time is 1-2h;

[0030] Step (3): after the heating is completed, take out the container containing the base asphalt from the oven, add the SBS modifier into the container, then put the container containing the base asphalt and SBS modifier on an electromagnetic oven for heating, stir and heat at the same time, until the base asphalt and SBS modifier are completely mixed, the heating temperature is raised to 160-170℃, and the heating time is 15-20min;

[0031] Step (4): put the container containing the base asphalt and SBS modifier into an oil bath pot and use a high-speed shearing instrument for shearing stirring, so as to prepare the SBS modified asphalt, the temperature of the oil bath pot is 160-170℃, the shearing speed is 5000-6000r / min, and the shearing stirring time is 0.5-1h;

[0032] Step (5): reduce the temperature of the oil bath pot to 100-120℃, then add D60 de-aromatic solvent oil using a stirrer while stirring, and the stirring time is 15-20 min, so that the SBS modified asphalt and the D60 de-aromatic solvent oil are fully mixed; continue to reduce the temperature of the oil bath pot to 60-80℃, then add D40 de-aromatic solvent oil using a stirrer while stirring, and the stirring time is 15-20 min, so that the D40 de-aromatic solvent oil is fully mixed;

[0033] Step (6): keep the temperature of the oil bath pot unchanged, continue to stir using a stirrer, add aromatic oil while stirring, and stir until the aromatic oil is fully mixed, the temperature of the oil bath pot is 60-80℃, and the stirring time is 15-20 min.

[0034] Step (7): keep the temperature of the oil bath pot unchanged, continue to stir using a stirrer, add anti-stripping agent while stirring, and stir until the anti-stripping agent is fully mixed, the temperature of the oil bath pot is 60-80℃, the stirring time is 15-20 min, and after the stirring is completed, the diluted asphalt is obtained.

[0035] In step three, the drying temperature of the asphalt pavement recycling material in each size fraction in the oil-rich state, the asphalt pavement recycling material in each size fraction in the oil-poor state, and the mineral powder is 100-110℃, and the drying time is 1-2h.

[0036] In step four, the asphalt pavement recycling material in each size fraction in the oil-rich state is placed in the first mixing pot for stirring, and the asphalt pavement recycling material in each size fraction in the oil-poor state is placed in the second mixing pot for stirring, and the stirring temperature is room temperature, the stirring speed is 70-100r / min, and the stirring time is 60-90s.

[0037] In step five, 70-80% of the old material activator is added to the first mixing pot, and 20-30% of the old material activator is added to the second mixing pot, the stirring temperature is room temperature, the stirring speed is 70-100r / min, and the stirring time is 60-90s.

[0038] In step six, the diluted asphalt is added to the first mixing pot for stirring, the stirring temperature is room temperature, the stirring speed is 70-100r / min, and the stirring time is 60-90s.

[0039] In step seven, the mineral powder is added to the first mixing pot for stirring, the stirring temperature is room temperature, the stirring speed is 70-100r / min, and the stirring time is 60-90s.

[0040] In the present application, the asphalt pavement recycling material in rich oil state includes two particle sizes, 3-5 mm and 0-3 mm, i.e. 3 mm≤particle size<5 mm and 0 mm<particle size<3 mm. The asphalt pavement recycling material in lean oil state includes five particle sizes, 19-21.5 mm, 16-19 mm, 13.2-16 mm, 9.5-13.2 mm and 4.75-9.5 mm, i.e. 19 mm≤particle size<21.5 mm, 16 mm≤particle size<19 mm, 13.2 mm≤particle size<16 mm, 9.5 mm≤particle size<13.2 mm and 4.75 mm≤particle size<9.5 mm. For each particle size, the material with a particle size between the upper and lower two sieve holes is obtained after the material passes through the upper and lower two sieve holes in turn, for example: the particle size is 16-19 mm (16 mm≤particle size<19 mm), i.e. the material with a particle size between 16-19 mm is obtained after the material passes through 19 mm sieve hole and 16 mm sieve hole in turn.

[0041] In the present application, the asphalt pavement recycling material (RAP) refers to the waste mixture recovered from the old asphalt pavement, which is obtained after milling, crushing, screening and other treatments, and its main components are old asphalt and old aggregate, and the outer surface of the old aggregate is partially or entirely coated with old asphalt. The asphalt pavement recycling material includes two states, rich oil RAP and lean oil RAP, wherein the rich oil RAP refers to the outer surface of the old aggregate being entirely coated with old asphalt, and the whole is old asphalt, and the lean oil RAP refers to the outer surface of the old aggregate not being coated with old asphalt or being partially coated with old asphalt, and the proportion of old asphalt is not more than 30% in the whole. It should be noted that after milling, crushing, screening and other treatments, the outside of the asphalt pavement recycling material is dust, which looks similar to sandy soil. When the asphalt pavement recycling material is mixed with the old material activator, the old material activator activates it, and at this time, the outer surface of the old aggregate is partially or entirely coated with old asphalt.

[0042] The particle size range of the asphalt pavement recycling material in rich oil state contains the oil layer thickness, and since the outer surface of the old aggregate in rich oil state is entirely coated with old asphalt, the oil layer thickness cannot be ignored. The particle size range of the asphalt pavement recycling material in lean oil state also contains the oil layer thickness, but the outer surface of the old aggregate in lean oil state is not coated with old asphalt or is partially coated with old asphalt, and even if the oil layer thickness is contained, the oil layer thickness can be ignored.

[0043] In the present application, D40 de-aromatic solvent oil, D60 de-aromatic solvent oil and aromatic oil are used in the preparation of dilution asphalt and old material activator, which is the first time in the cold recycling asphalt mixture preparation technology and is an important material for preparing cold recycling asphalt mixture. In the preparation of dilution asphalt, the mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil is used as a diluent, and the final prepared dilution asphalt still maintains good flow state at room temperature after cooling, and can be mixed with asphalt pavement recycling material at room temperature; the addition of aromatic oil in the preparation of dilution asphalt can lay a foundation for promoting the fusion of new and old asphalt in the subsequent preparation of asphalt mixture process.

[0044] In the preparation of old material activator, D40 de-aromatic solvent oil, D60 de-aromatic solvent oil and aromatic oil are used, and the synergistic effect of the three substances can fully activate the old asphalt on the surface of asphalt pavement recycling material in rich oil state and lean oil state, which is beneficial to promote the mutual fusion between new asphalt and old asphalt in the preparation of asphalt mixture.

[0045] D40 de-aromatic solvent oil and D60 de-aromatic solvent oil are colorless, non-toxic, small odor, strong solubility, good volatility, and the content of saturated hydrocarbon is more than 99.9%, and have good oxidation stability; under the condition of room temperature and natural ventilation, D40 de-aromatic solvent oil and D60 de-aromatic solvent oil can be used normally without special safety and fire prevention measures, the contact danger is very low, the production and construction process is safer, and the influence on atmospheric environment and worker health is very small; the volatilization speed of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil is good, and the volatilization degree is complete, which can ensure that there is enough time for full paving and compaction at the construction site, and the influence of the two substances on the performance of cold recycling asphalt mixture is small.

[0046] In the present application, the synergistic effect among the asphalt pavement recycling material (including rich oil RAP and lean oil RAP), the diluent (D40+D60+aromatic oil), the old material activator (D40+D60+aromatic oil) and other substances makes the new and old asphalt quickly blend at room temperature, realizes physical modification, maximizes the regeneration ratio of RAP material (including fine particle size and coarse particle size), reduces the amount of new asphalt (the amount of new asphalt is not more than 1%), improves the road performance of cold recycling asphalt mixture, and can be used for paving middle surface layer of asphalt pavement.

[0047] By using the mixture of D40 and D60, the volatilization gradient can be controlled, the early performance development rate of the recycled mixture can be significantly improved, and the curing time can be shortened. A small amount of new asphalt can only cover a limited surface area of RAP, but after adding the diluent, its low viscosity enables it to rapidly spread and penetrate into almost all RAP particle surfaces and internal pores, so that the not more than 1% new asphalt can touch and act on several times the mass of aged asphalt.

[0048] The aged asphalt is activated and regenerated by the old material activator, and the diluted new asphalt has good fluidity and permeability at room temperature. The two quickly fuse to form a new type of blended binder phase with homogeneity and high performance, so that the aged asphalt in the RAP is transformed from "waste" to the main effective component of the mixture binder phase. This "activation of RAP asphalt as the main component, and a small amount of new asphalt to optimize and improve" synergistic strategy overturns the traditional cold regeneration which relies on a large amount of new asphalt to provide binding force, so as to realize the dual goals of 100% RAP utilization and minimization of new asphalt usage (≤1%) while ensuring excellent road performance (which can be used for the middle surface layer).

[0049] Through the old material activator, the performance of the aged asphalt has been greatly restored, and it can bear the bonding function again. The new asphalt does not need to be the main binder, and only a small amount of key components of the old asphalt is needed to supplement. This makes most of the aged asphalt in RAP be effectively utilized as the main body of the mixture binder phase, and fundamentally reduces the demand for the total amount of new asphalt. The rapid and uniform fusion of a small amount of new asphalt and a large amount of activated RAP asphalt forms a new type of blended asphalt with performance better than that of aged asphalt and close to that of new asphalt. This process is efficiently completed at room temperature, so that the overall bonding phase performance is significantly improved with a small amount of new asphalt.

[0050] In the present application, D40 de-aromatic solvent oil, D60 de-aromatic solvent oil and aromatic oil are mixed in advance to prepare the old material activator, and then the old material activator is first added to the asphalt pavement recycling material (including oil-rich RAP and oil-poor RAP) for mixing.

[0051] Regarding the first addition of the old material activator: D40 rapidly penetrates into the surface layer of the aged asphalt to reduce the local viscosity at the initial stage of mixing due to its extremely low viscosity and small molecular weight, and D60 expands the penetration depth and maintains a long-term softening effect. Aromatic oil is rich in aromatic components and is a strong solvent for asphaltene, which can directly disassemble the asphaltene network and supplement the light oil components (saturated components, aromatic components) lost during the aging process to improve the colloidal stability. The chemical properties of the activated aged asphalt and the new asphalt are significantly reduced, and the compatibility is greatly improved, which is beneficial to the fusion of new and old asphalt into a whole.

[0052] The description of the pot mixing activation of the rich-oil RAP and the lean-oil RAP: if the rich-oil RAP (fine particle size) and the lean-oil RAP (coarse particle size) are mixed with the old material activator, the old material activator can be absorbed by the coarse aggregate voids in a large amount, resulting in an insufficient dosage for activating the aged asphalt. The pot mixing can make the old material activator more fully contact with the aged asphalt in the rich-oil RAP and the aged asphalt on the surface of the lean-oil RAP, reduce the invalid absorption by the coarse aggregate, and thus improve the utilization rate of the old material activator. Meanwhile, the pot mixing can help to avoid the early sticking problem of the coarse and fine RAP materials, make the RAP materials more evenly coated by the asphalt, reduce the whitening material phenomenon, and improve the uniformity of the mixture.

[0053] In the whole process of preparing the cold recycled asphalt mixture, the selection and ratio of the substances, the adding sequence of the substances, the process parameters of the steps, and the selection and ratio of the three substances in the old material activator and the adding timing of the old material activator (the old material activator is first added to the asphalt pavement recycling material for mixing) are all very crucial. Only the synergistic effect of the various formula parameters and process parameters can achieve the technical effect expected by the present application.

[0054] The present application has the following beneficial effects:

[0055] (1) The present application uses D40 de-aromatic solvent oil and D60 de-aromatic solvent oil as the diluent and the component of the old material activator, starts from solving the fast fusion of new and old asphalt at room temperature, and develops the full-RAP cold recycled asphalt mixture based on a small amount of new asphalt through physical modification (keeping the diluted asphalt in a good flowing state at room temperature, which can be mixed with the asphalt pavement recycling material at room temperature), 100% RAP formula design (combining the rich-oil asphalt pavement recycling material and the lean-oil asphalt pavement recycling material to replace all aggregates), new asphalt dosage control (the new asphalt addition amount is not more than 1% of the asphalt mixture), and process innovation (especially mixing the D40 de-aromatic solvent oil, the D60 de-aromatic solvent oil and the aromatic oil in advance to prepare the old material activator, and then making the old material activator first mixed with the asphalt pavement recycling material), breaks through the technical bottlenecks of the cold recycling technology in the application at a higher level, the maximum RAP recycling ratio, and the reduction of the new asphalt amount, and develops the full-RAP cold recycled asphalt mixture based on a small amount of new asphalt.

[0056] (2) This invention proposes for the first time the use of D40 dearomatic solvent oil and D60 dearomatic solvent oil in the preparation technology of cold recycled asphalt mixture. When preparing diluted asphalt, the mixture of D40 dearomatic solvent oil and D60 dearomatic solvent oil is used as a diluent, which can keep the diluted asphalt in a good flow state at room temperature and can be directly mixed with RAP material at room temperature. D40 dearomatic solvent oil and D60 dearomatic solvent oil are also used when preparing old material activator. The two substances, when used in combination with aromatic oil, can fully activate the old asphalt in the recycled asphalt pavement material, which is conducive to promoting the rapid fusion of new and old asphalt at room temperature.

[0057] (3) The present invention uses recycled asphalt pavement material to replace all aggregates, including both coarse-grained RAP material and fine-grained RAP material, thereby maximizing the proportion of recycled RAP material, while only adding a trace amount of new asphalt.

[0058] (4) The D40 dearomatic solvent oil and D60 dearomatic solvent oil used in this invention are excellent solvents that are highly environmentally friendly and pollution-free. They are colorless, non-toxic, and have very little odor, which can provide workers with a good construction environment. At the same time, the aromatic content is less than 0.03wt% and the sulfur content is less than 0.2mg / kg, resulting in low emissions and minimal impact on the environment.

[0059] (5) The D40 dearomatic solvent oil and D60 dearomatic solvent oil used in this invention have a fast dissolution rate with asphalt. They can activate the aged asphalt on the surface of the recycled asphalt pavement material at room temperature, reduce its viscosity, and promote the good integration of new and old asphalt, thereby improving the cohesion of cold recycled asphalt mixture.

[0060] (6) The cold recycled asphalt mixture prepared by the present invention has excellent comprehensive performance and can meet the performance requirements of hot-mix asphalt mixtures for the surface layer of highways, first-class highways and other grades of roads, thus realizing the utilization of higher layers.

[0061] (7) The cold recycled asphalt mixture prepared by the present invention can quickly form strength and can be laid on the surface layer more quickly, thereby shortening the waiting time for the road to open to traffic and reducing the impact on road traffic. Attached Figure Description

[0062] Figure 1 This is a process flow diagram of a preferred embodiment of the cold recycled asphalt mixture based on trace amounts of new asphalt and its preparation method according to the present invention;

[0063] Figure 2 for Figure 1 A photograph of the asphalt pavement recycling material (oil-rich RAP) in the illustrated embodiment;

[0064] Figure 3 for Figure 1A photograph of a bituminous pavement recycling material (lean RAP) in the embodiment shown;

[0065] Figure 4 For Figure 1 A photograph of an old material activator prepared in the embodiment shown;

[0066] Figure 5 For Figure 1 A photograph of a bituminous pavement recycling material (lean RAP) in the embodiment shown;

[0067] Figure 6 For Figure 1 A photograph of a bituminous pavement recycling material (lean RAP) in the embodiment shown;

[0068] Figure 7 For Figure 1 A photograph of a dilution bitumen prepared in the embodiment shown;

[0069] Figure 8 For Figure 1 A photograph of a full-RAP cold recycling bituminous mixture based on a trace amount of new bitumen prepared in the embodiment shown. DETAILED DESCRIPTION

[0070] In order to further understand the inventive content of the present application, the present application will be described in detail below in combination with specific embodiments.

[0071] Embodiment One:

[0072] According to a preferred embodiment of the full-RAP cold recycling bituminous mixture based on a trace amount of new bitumen of the present application, the mass percentage of each substance in the cold recycling bituminous mixture is 96.5wt% of a bituminous pavement recycling material, 0.9wt% of a dilution bitumen, 1.8wt% of an old material activator, and 0.8wt% of a mineral powder; a mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil is used as a diluent in the dilution bitumen, and the old material activator contains D40 de-aromatic solvent oil and D60 de-aromatic solvent oil.

[0073] The bituminous pavement recycling material is composed of a rich-oil bituminous pavement recycling material and a lean-oil bituminous pavement recycling material, and the mass percentage of the rich-oil bituminous pavement recycling material and the lean-oil bituminous pavement recycling material in the bituminous pavement recycling material is both 50%.

[0074] The rich-oil bituminous pavement recycling material includes two grades of particle sizes, 3-5mm and 0-3mm, and the mass percentage of each grade of particle size in the rich-oil bituminous pavement recycling material is 75wt% of particle size 3-5mm and 25wt% of particle size 0-3mm.

[0075] The lean oil state asphalt pavement recycling material includes five particle size grades, 19-21.5mm, 16-19mm, 13.2-16mm, 9.5-13.2mm, 4.75-9.5mm, and the mass percentage of each particle size grade in the lean oil state asphalt pavement recycling material is 7wt% for the particle size 19-21.5mm, 15wt% for the particle size 16-19mm, 8wt% for the particle size 13.2-16mm, 20wt% for the particle size 9.5-13.2mm, and 50wt% for the particle size 4.75-9.5mm.

[0076] The mass percentage of each substance in the dilution asphalt is 67.5wt% for the base asphalt, 3wt% for the SBS modifier, 0.5wt% for the anti-stripping agent, 26.5wt% for the diluent, and 2.5wt% for the aromatic oil; the diluent is a mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil, and the mass percentage of each substance in the diluent is 40wt% for the D40 de-aromatic solvent oil and 60wt% for the D60 de-aromatic solvent oil.

[0077] The mass percentage of each substance in the old material activator is 42wt% for the D40 de-aromatic solvent oil, 42wt% for the D60 de-aromatic solvent oil, and 16wt% for the aromatic oil.

[0078] In this embodiment, the base asphalt is No. 70 base asphalt; the SBS modifier is linear SBS modifier; and the anti-stripping agent is non-amine anti-stripping agent, which is a nitrogen-containing complex, and the nitrogen-containing complex is AR-2 type anti-stripping agent produced by Shenzhen Jinlong Chemical Technology Co., Ltd., and is a liquid.

[0079] In this embodiment, the D40 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatic hydrogenation refining and fractionation from straight-run distillate oil, hydrocracking distillate oil or low-sulfur straight-run aviation kerosene, and has a distillation range of 150-200℃, a closed flash point of 40-50℃, an aromatic content of less than 0.03wt%, a sulfur content of less than 0.2mg / kg, and a saturated hydrocarbon content of more than 99.9%. The D60 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatic hydrogenation refining and fractionation from straight-run distillate oil, hydrocracking distillate oil or low-sulfur straight-run aviation kerosene, and has a distillation range of 180-230℃, a closed flash point of 60-70℃, an aromatic content of less than 0.03wt%, a sulfur content of less than 0.2mg / kg, and a saturated hydrocarbon content of more than 99.9%. The flash point of the aromatic oil is not less than 200℃, the density is 0.99-1.02g / cm 3 , the kinematic viscosity at 100℃ is 15-22mm 2The D40 de-aromatic solvent oil and the D60 de-aromatic solvent oil are both produced by Jinan Yuan Yang Chemical Co., Ltd., and the aromatic oil is produced by Shandong Furunada Chemical Co., Ltd.

[0080] As shown in the drawings, the embodiment also provides a preparation method of the full-RAP cold recycled asphalt mixture based on a small amount of new asphalt, which is used for preparing the full-RAP cold recycled asphalt mixture based on a small amount of new asphalt, and comprises the following steps in sequence: Figure 1 Step one: dilute asphalt is prepared according to the designed material ratio and process parameters, and is stored for standby at normal temperature;

[0081] Step two: the D40 de-aromatic solvent oil, the D60 de-aromatic solvent oil and the aromatic oil are mixed uniformly according to the designed material ratio, so as to prepare old material activator, which is stored for standby at normal temperature;

[0082] Step three: the asphalt pavement recycling materials in the oil-rich state of each size range, the asphalt pavement recycling materials in the oil-poor state of each size range and the mineral powder are respectively put into an oven for drying treatment, and after the drying treatment is completed, the asphalt pavement recycling materials in the oil-rich state of each size range, the asphalt pavement recycling materials in the oil-poor state of each size range and the mineral powder are respectively taken out from the oven and naturally cooled to normal temperature for standby;

[0083] Step four: the asphalt pavement recycling materials in the oil-rich state of each size range are put into a first mixing pot and stirred by using a stirrer, and the asphalt pavement recycling materials in the oil-poor state of each size range are put into a second mixing pot and stirred by using a stirrer;

[0084] Step five: part of the old material activator is added into the first mixing pot and continuously stirred by using the stirrer, and the remaining old material activator is added into the second mixing pot and continuously stirred by using the stirrer, and after the stirring is completed, the materials in the second mixing pot are all transferred into the first mixing pot;

[0085] Step six: the dilute asphalt is added into the first mixing pot and continuously stirred by using the stirrer;

[0086] Step seven: the mineral powder is added into the first mixing pot and continuously stirred by using the stirrer, and after the stirring is completed, the full-RAP cold recycled asphalt mixture based on a small amount of new asphalt can be prepared.

[0087] In step one, the preparation method of the dilute asphalt comprises the following steps in sequence:

[0088] Step (1): base asphalt, SBS modifier, anti-stripping agent, D40 de-aromatic solvent oil, D60 de-aromatic solvent oil and aromatic oil are weighed according to the designed material ratio for standby;

[0089] Step (2): the base asphalt, the SBS modifier, the anti-stripping agent, the D40 de-aromatic solvent oil, the D60 de-aromatic solvent oil and the aromatic oil are mixed uniformly to prepare the dilute asphalt, which is stored for standby at normal temperature.

[0090] Step (2): Put the base asphalt into a container, and then put the container containing the base asphalt into an oven for heating, the heating temperature is 110℃, and the heating time is 1.5h;

[0091] Step (3): After the heating is completed, the container containing the base asphalt is taken out of the oven, the SBS modifier is added into the container, and then the container containing the base asphalt and the SBS modifier is placed on the electromagnetic oven for heating, and the temperature is increased while stirring until the base asphalt and the SBS modifier are completely mixed, the heating temperature is increased to 165℃, and the heating time is 17.5min;

[0092] Step (4): Put the container containing the base asphalt and the SBS modifier into an oil bath pot, and use a high-speed shearing instrument for shearing stirring, thereby obtaining the SBS modified asphalt, the temperature of the oil bath pot is 165℃, the shearing speed is 5500r / min, and the shearing stirring time is 0.75h;

[0093] Step (5): The temperature of the oil bath pot is reduced to 110℃, and then the D60 de-aromatic solvent oil is added while stirring by using a stirrer, and the stirring time is 17.5min, so that the SBS modified asphalt and the D60 de-aromatic solvent oil are completely mixed; the temperature of the oil bath pot is continuously reduced to 70℃, and then the D40 de-aromatic solvent oil is added while stirring by using a stirrer, and the stirring time is 17.5min, so that the D40 de-aromatic solvent oil is completely mixed;

[0094] Step (6): The temperature of the oil bath pot is kept unchanged, and the stirring is continued by using a stirrer, and the aromatic oil is added while stirring, and the stirring is continued until the aromatic oil is completely mixed, the temperature of the oil bath pot is 70℃, and the stirring time is 17.5min;

[0095] Step (7): The temperature of the oil bath pot is kept unchanged, and the stirring is continued by using a stirrer, and the anti-stripping agent is added while stirring, and the stirring is continued until the anti-stripping agent is completely mixed, the temperature of the oil bath pot is 70℃, the stirring time is 17.5min, and after the stirring is completed, the diluted asphalt is obtained.

[0096] In step three, the drying temperature of the asphalt pavement recycling material in each size fraction in the oil-rich state, the asphalt pavement recycling material in each size fraction in the oil-poor state, and the mineral powder is 105℃, and the drying time is 1.5h.

[0097] In step four, the asphalt pavement recycling material in each size fraction in the oil-rich state is placed into a first mixing pot for stirring, and the asphalt pavement recycling material in each size fraction in the oil-poor state is placed into a second mixing pot for stirring, the stirring temperature is room temperature, the stirring speed is 85r / min, and the stirring time is 75s.

[0098] In step five, 75% of the old material activator is added to the first mixing pot and 25% of the old material activator is added to the second mixing pot, both at room temperature, at a stirring speed of 85 r / min, and for a stirring time of 75 s.

[0099] In step six, the diluted asphalt is added to the first mixing pot and stirred at room temperature, at a stirring speed of 85 r / min, and for a stirring time of 75 s.

[0100] In step seven, the mineral powder is added to the first mixing pot and stirred at room temperature, at a stirring speed of 85 r / min, and for a stirring time of 75 s.

[0101] In this embodiment, the asphalt pavement recycling material in the rich oil state and the asphalt pavement recycling material in the lean oil state used are as shown in Figure 2 and Figure 3 respectively, the prepared old material activator is as shown in Figure 4 , the substance after mixing the asphalt pavement recycling material in the rich oil state with the old material activator is as shown in Figure 5 , the substance after mixing the asphalt pavement recycling material in the lean oil state with the old material activator is as shown in Figure 6 , the prepared diluted asphalt is as shown in Figure 7 , and the prepared full-RAP cold recycled asphalt mixture based on a small amount of new asphalt is as shown in Figure 8 .

[0102] The micro-new asphalt based full RAP cold recycled asphalt mixture and the preparation method have the following beneficial effects: (1) D40 and D60 de-aromatic solvent oil are used as the components of the diluent and the old material activator, starting from solving the rapid fusion of new and old asphalt at room temperature, through physical modification, 100% RAP formula design, new asphalt dosage control and process innovation, the technical bottlenecks of cold recycling technology in the aspects of application at a higher level, maximum RAP material regeneration ratio and less new asphalt dosage are broken through. (2) D40 and D60 de-aromatic solvent oil are first used in the cold recycled asphalt mixture preparation technology, wherein the mixture of D40 and D60 de-aromatic solvent oil is used as the diluent when preparing the diluted asphalt, so that the diluted asphalt can maintain a good flow state at room temperature; D40 and D60 de-aromatic solvent oil are also used in the preparation of the old material activator, and are used in combination with aromatic oil to fully activate the old asphalt in the asphalt pavement recycling material, which is conducive to promoting the rapid fusion of new and old asphalt at room temperature. (3) The asphalt pavement recycling material is used to replace all aggregates, including RAP materials of coarse and fine particle sizes, so that the RAP material regeneration ratio is maximized, and only a small amount of new asphalt is added. (4) The prepared cold recycled asphalt mixture has excellent comprehensive performance, can perfectly meet the performance requirements of the hot mixed asphalt mixture of the middle surface layer, and realizes the utilization at a higher level. (5) The prepared cold recycled asphalt mixture can quickly form strength, and the upper surface layer can be paved in advance, so as to shorten the waiting time for opening traffic and reduce the influence on road traffic.

[0103] Embodiment two

[0104] According to another preferred embodiment of the micro-new asphalt based full RAP cold recycled asphalt mixture, the material ratio, preparation process, used equipment, technical principle and beneficial effects are basically the same as those of the first embodiment, except that:

[0105] The mass percentage of each substance in the cold recycled asphalt mixture is 96wt% of the asphalt pavement recycling material, 1wt% of the diluted asphalt, 2wt% of the old material activator and 1wt% of the mineral powder; the mixture of D40 and D60 de-aromatic solvent oil is used as the diluent in the diluted asphalt, and the old material activator contains D40 and D60 de-aromatic solvent oil.

[0106] The asphalt pavement recycling material is composed of asphalt pavement recycling material in a rich oil state and asphalt pavement recycling material in a lean oil state, and the mass percentage of the asphalt pavement recycling material in the rich oil state and the asphalt pavement recycling material in the lean oil state in the asphalt pavement recycling material is 50%.

[0107] The rich-oil-state asphalt pavement recycling material includes two particle sizes, 3-5mm and 0-3mm, and the mass percentage of each particle size in the rich-oil-state asphalt pavement recycling material is 70wt% for the particle size of 3-5mm and 30wt% for the particle size of 0-3mm.

[0108] The lean-oil-state asphalt pavement recycling material includes five particle sizes, 19-21.5mm, 16-19mm, 13.2-16mm, 9.5-13.2mm and 4.75-9.5mm, and the mass percentage of each particle size in the lean-oil-state asphalt pavement recycling material is 5wt% for the particle size of 19-21.5mm, 18wt% for the particle size of 16-19mm, 6wt% for the particle size of 13.2-16mm, 23wt% for the particle size of 9.5-13.2mm and 48wt% for the particle size of 4.75-9.5mm.

[0109] The mass percentage of each substance in the diluted asphalt is 65wt% for the base asphalt, 4wt% for the SBS modifier, 0.2wt% for the anti-stripping agent, 28wt% for the diluent and 2.8wt% for the aromatic oil; the diluent is a mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil, and the mass percentage of each substance in the diluent is 30wt% for the D40 de-aromatic solvent oil and 70wt% for the D60 de-aromatic solvent oil.

[0110] The mass percentage of each substance in the old material activator is 40wt% for the D40 de-aromatic solvent oil, 40wt% for the D60 de-aromatic solvent oil and 20wt% for the aromatic oil.

[0111] In step one, the preparation method of the diluted asphalt includes the following main process parameters: step (2), the base asphalt is put into an oven for heating, the heating temperature is 100℃, and the heating time is 2h; step (3), the SBS modifier is added into the base asphalt for heating, the heating temperature is 160℃, and the heating time is 20min; step (4), the base asphalt and the SBS modifier are put into an oil bath pot for shearing stirring, the temperature of the oil bath pot is 160℃, the shearing speed is 6000r / min, and the shearing stirring time is 1h; step (5), the temperature of the oil bath pot is reduced to 100℃, then the D60 de-aromatic solvent oil is added for stirring, the stirring time is 20min, the temperature of the oil bath pot is continuously reduced to 60℃, then the D40 de-aromatic solvent oil is added for stirring, the stirring time is 20min; step (6), the aromatic oil is added into the oil bath pot for continuous stirring, the temperature of the oil bath pot is 60℃, and the stirring time is 20min; step (7), the anti-stripping agent is added into the oil bath pot for continuous stirring, the temperature of the oil bath pot is 60℃, and the stirring time is 20min.

[0112] In step three, the drying temperature of the asphalt pavement recycling material in oil-rich state of each particle size, the asphalt pavement recycling material in oil-poor state of each particle size, and the mineral powder is 100 DEG C, and the drying time is 2h.

[0113] In step four, the asphalt pavement recycling material in oil-rich state of each particle size is put into the first mixing pot for stirring, and the asphalt pavement recycling material in oil-poor state of each particle size is put into the second mixing pot for stirring, wherein the stirring temperature is normal temperature, the stirring speed is 70 r / min, and the stirring time is 90s.

[0114] In step five, 70% of the old material activator is added into the first mixing pot, and 30% of the old material activator is added into the second mixing pot, wherein the stirring temperature is normal temperature, the stirring speed is 70 r / min, and the stirring time is 90s.

[0115] In step six, the dilution asphalt is added into the first mixing pot for stirring, wherein the stirring temperature is normal temperature, the stirring speed is 70 r / min, and the stirring time is 90s.

[0116] In step seven, the mineral powder is added into the first mixing pot for stirring, wherein the stirring temperature is normal temperature, the stirring speed is 70 r / min, and the stirring time is 90s.

[0117] Example three:

[0118] According to another preferred embodiment of the full RAP cold recycled asphalt mixture based on trace new asphalt provided by the application, the material ratio, preparation process, used equipment, technical principle, beneficial effects and the like are basically the same as those of example one, and the difference is that:

[0119] The mass percentage of each substance in the cold recycled asphalt mixture is 97wt% of the asphalt pavement recycling material, 0.8wt% of the dilution asphalt, 1.5wt% of the old material activator, and 0.7wt% of the mineral powder; the mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil is used as the diluent in the dilution asphalt, and the old material activator contains D40 de-aromatic solvent oil and D60 de-aromatic solvent oil.

[0120] The asphalt pavement recycling material is composed of the asphalt pavement recycling material in oil-rich state and the asphalt pavement recycling material in oil-poor state, and the mass percentage of the asphalt pavement recycling material in oil-rich state and the asphalt pavement recycling material in oil-poor state in the asphalt pavement recycling material is 50%.

[0121] The asphalt pavement recycling material in oil-rich state includes two particle sizes, which are 3-5mm and 0-3mm, and the mass percentage of each particle size in the asphalt pavement recycling material in oil-rich state is 80wt% of the particle size 3-5mm and 20wt% of the particle size 0-3mm.

[0122] The lean oil state asphalt pavement recycling material includes five particle size grades, 19-21.5mm, 16-19mm, 13.2-16mm, 9.5-13.2mm, 4.75-9.5mm, and the mass percentage of each particle size grade in the lean oil state asphalt pavement recycling material is 8wt% for the particle size 19-21.5mm, 12wt% for the particle size 16-19mm, 10wt% for the particle size 13.2-16mm, 18wt% for the particle size 9.5-13.2mm, and 52wt% for the particle size 4.75-9.5mm.

[0123] The mass percentage of each substance in the dilution asphalt is 70wt% for the base asphalt, 2wt% for the SBS modifier, 0.5wt% for the anti-stripping agent, 25.5wt% for the diluent, and 2wt% for the aromatic oil; the diluent is a mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil, and the mass percentage of each substance in the diluent is 50wt% for the D40 de-aromatic solvent oil and 50wt% for the D60 de-aromatic solvent oil.

[0124] The mass percentage of each substance in the old material activator is 45wt% for the D40 de-aromatic solvent oil, 45wt% for the D60 de-aromatic solvent oil, and 10wt% for the aromatic oil.

[0125] In step one, the preparation method of the dilution asphalt includes the following main process parameters: step (2), the base asphalt is heated in an oven, the heating temperature is 120℃, and the heating time is 1h; step (3), the SBS modifier is added to the base asphalt for heating, the heating temperature is 170℃, and the heating time is 15min; step (4), the base asphalt and the SBS modifier are put into an oil bath pot for shearing stirring, the temperature of the oil bath pot is 170℃, the shearing speed is 5000r / min, and the shearing stirring time is 0.5h; step (5), the temperature of the oil bath pot is reduced to 120℃, then the D60 de-aromatic solvent oil is added for stirring, the stirring time is 15min, the temperature of the oil bath pot is continuously reduced to 80℃, then the D40 de-aromatic solvent oil is added for stirring, the stirring time is 15min; step (6), the aromatic oil is added to the oil bath pot for continuous stirring, the temperature of the oil bath pot is 80℃, and the stirring time is 15min; step (7), the anti-stripping agent is added to the oil bath pot for continuous stirring, the temperature of the oil bath pot is 80℃, and the stirring time is 15min.

[0126] In step three, the drying temperature of each particle size grade of the rich oil state asphalt pavement recycling material, each particle size grade of the lean oil state asphalt pavement recycling material, and the mineral powder is 110℃, and the drying time is 1h.

[0127] In step four, the asphalt pavement recycling materials of each grade particle size in oil-rich state are put into the first mixing pot for stirring, and the asphalt pavement recycling materials of each grade particle size in oil-poor state are put into the second mixing pot for stirring, the stirring temperature is normal temperature, the stirring speed is 100 r / min, and the stirring time is 60 s.

[0128] In step five, 80% of the old material activator is added into the first mixing pot, and 20% of the old material activator is added into the second mixing pot, the stirring temperature is normal temperature, the stirring speed is 100 r / min, and the stirring time is 60 s.

[0129] In step six, the diluted asphalt is added into the first mixing pot for stirring, the stirring temperature is normal temperature, the stirring speed is 100 r / min, and the stirring time is 60 s.

[0130] In step seven, the mineral powder is added into the first mixing pot for stirring, the stirring temperature is normal temperature, the stirring speed is 100 r / min, and the stirring time is 60 s.

[0131] The early stability, molding stability, water stability, dynamic stability and other performance tests are carried out on the full RAP cold recycled asphalt mixtures prepared in the above three embodiments based on micro new asphalt, the test equipment, test environment, test conditions, sample shape and size are the same, three sets of parallel tests are carried out for each performance test, and then the average value is taken.

[0132] I. Initial stability and molding stability test

[0133] The cold recycled asphalt mixture with a mass of 980 g (the actual mass is taken as the standard for controlling the height of the test piece 63.5±1.5 mm) is weighed and loaded into the test mold, and is double-sidedly tamped for 50 times. After being vertically placed at room temperature for 2 h, the test piece is demolded. After being cured in a water tank at 25±1℃ for 30 min, the Marshall stability of the test piece is measured, which is the initial stability. The test results are shown in Table 1.

[0134] The cold recycled asphalt mixture with a mass of 1100 g (the actual mass is taken as the standard for controlling the height of the test piece 63.5±1.5 mm) is weighed and loaded into the test mold, and is double-sidedly tamped for 50 times. The test piece is placed in a 105±5℃ oven together with the test mold in a vertical manner for 24 h, and after being taken out, it is double-sidedly tamped for 25 times. Then, the test piece is vertically placed together with the test mold at room temperature for 24 h, and is demolded. After being cured in a water tank at 60±1℃ for 30 min, the Marshall stability of the test piece is measured, which is the molding stability. The test results are shown in Table 2. The test results are shown in Table 1.

[0135] Table 1 Test results of initial stability and molding stability of cold recycled asphalt mixture

[0136]

[0137] II. Water stability test

[0138] The cold recycled asphalt mixture with a mass of 1170g (actual mass is based on the controlled specimen height of 63.5±1.5mm) was placed in the mold and compacted for 50 times on both sides. The specimen together with the mold was placed in a 105±5℃ oven in a vertical side-up manner for 48h, after which it was removed and compacted for 25 times on both sides, and then removed from the mold after being placed vertically at room temperature for 24h.

[0139] The specimens were randomly divided into two groups, and the number of specimens in one group should not be less than 4. One group of specimens was placed in a 60℃ constant temperature water tank for 60min and then subjected to the Marshall test, and the other group of specimens was placed in a 60℃ constant temperature water tank for 48h and then subjected to the Marshall test. The ratio of the two is the residual stability ratio, and the test results are shown in Table 2.

[0140] Table 2 Test results of immersion residual stability of cold recycled asphalt mixture

[0141]

[0142] The specimens were randomly divided into two groups, each group not less than 4. The first group of specimens was placed on the platform and stored at room temperature for standby. The second group of specimens was placed in a vacuum dryer, the water inlet hose was closed, the vacuum pump was started, the vacuum degree of the dryer was above 98.3kPa (730mmHg), and maintained for 15min, then the water inlet hose was opened, and the cold water flow was introduced into the water through the negative pressure to immerse the specimen in water, and after 15min of immersion, the atmospheric pressure was restored. The second group of specimens was taken out and placed in a plastic bag, about 10mL of water was added, the bag opening was tied tightly, the specimen was placed in a constant temperature refrigerator, the freezing temperature was-18℃±2℃, and maintained for 16±1h. The specimen was taken out and immediately placed in a 60±0.5℃ constant temperature water tank, soaked for 3min, and then the plastic bag was removed and continued to be soaked for 24h±30min. The first group and the second group of specimens were immersed in a constant temperature water tank with a temperature of 25±0.5℃ for 2h±10min. The test results of the first group of specimens are the splitting strength, and the ratio of the second group to the first group is the freeze-thaw splitting tensile strength ratio, and the test results are shown in Table 3.

[0143] Table 3 Test results of splitting strength and freeze-thaw splitting strength of cold recycled asphalt mixture

[0144]

[0145] III. Dynamic stability test

[0146] A test mold with a length of 300 mm, a width of 300 mm, and a thickness of 50 mm is used. After the mixed cold recycled asphalt mixture is slightly mixed with a small shovel, it is evenly loaded into the test mold along the edge to the center in sequence, and the middle part is slightly higher than the periphery. Before molding, the rolling wheel is preheated to about 80°C, then the test mold containing the asphalt mixture is placed on the platform of the wheel roller, the rolling wheel is gently lowered, the total load is adjusted to 9 kN (linear load 300 N / cm), the wheel roller is started, and after rolling for 2 rounds (4 times), it is stopped, the load is removed, the test piece is turned over, the same load is added, and the test piece is rolled until the surface of the test piece is flush with the top edge of the test mold. After the test piece is rolled, it is quickly placed in a 60°C electric hot air drying oven and dried to constant weight.

[0147] The test piece is placed in a constant temperature room that has reached a test temperature of 60±1°C, and is kept at a temperature of 5-12h. The test piece is moved to the test bench of the wheel tracking test machine, and the test wheel is in the central part of the test piece, and the walking direction must be consistent with the rolling or driving direction of the test piece. The test temperature is 60°C, and the wheel pressure is 0.7 MPa. Start the wheel tracking deformation automatic recording instrument, start the test machine, and make the test wheel walk back and forth for about 1h, which completes the wheel tracking test. The test results are shown in Table 4.

[0148] Table 4 Test results of dynamic stability of cold recycled asphalt mixture

[0149]

[0150] As can be seen from the test results in Tables 1-4, the cold recycled asphalt mixture prepared in the above examples has excellent comprehensive performance, and can meet the performance requirements of hot-mixed asphalt mixture for surface layer of expressway, first-class highway and other grade roads. According to the requirements of “Technical Specification for Construction of Highway Asphalt Pavement” (JTG F40-2004), the Marshall stability of hot-mixed asphalt mixture for surface layer of expressway, first-class highway and other grade roads is not less than 5 KN, the residual stability of Marshall test after immersion in water is not less than 80%, the residual strength ratio of freeze-thaw splitting test is not less than 75%, and the dynamic stability is not less than 1000. The initial stability is more than 3 times higher than the requirement of 3 kN in “Technical Specification for Construction of Highway Asphalt Pavement” (JTG F40-2004).

[0151] The oven, mixing pot, oil bath pot, stirrer and other equipment used in the above examples are conventional equipment in the art, and the model, structure and other aspects of the equipment are not specially required. The AR-2 type anti-stripping agent used in the above examples is purchased from Shenzhen Jinlong Chemical Technology Co., Ltd., the D40 and D60 de-aromatic solvent oils are purchased from Jinan Yuan Yang Chemical Co., Ltd., the aromatic oil is purchased from Shandong Furuanda Chemical Co., Ltd., and the asphalt pavement recycled material, mineral powder, No. 70 base asphalt, linear SBS modifier and other materials are purchased from Beijing Municipal Road & Bridge Materials Group Co., Ltd.

[0152] Particularly, the technical solutions of the present application involve many parameters, and the beneficial effects and significant progress of the present application can be obtained only by comprehensively considering the synergistic effect between each parameter. Moreover, the value range of each parameter in the technical solution is obtained through a large number of experiments. For each parameter and the mutual combination of each parameter, the inventors have recorded a large amount of experimental data. Due to the limited space, the specific experimental data is not disclosed here.

[0153] It is not difficult for those skilled in the art to understand that the present application includes any combination of the parts shown in the summary and the specific embodiment part of the present application specification and the drawings. Due to the limited space and in order to make the specification brief, each scheme formed by these combinations is not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A micro-new bituminous based full RAP cold recycled asphalt mixture characterized in that: The mass percentage of each substance in the cold recycled asphalt mixture is 96-97wt% of asphalt pavement recycling material, 0.8-1wt% of dilution asphalt, 1.5-2wt% of old material activator, and 0.5-1wt% of mineral powder; the mixture of D40 and D60 de-aromatic solvent oil is used as the diluent in the dilution asphalt, and the old material activator contains D40 and D60 de-aromatic solvent oil; The preparation method of the cold recycled asphalt mixture comprises the following steps in sequence: Step one: prepare the dilution asphalt according to the designed material ratio and process parameters, and store it at room temperature for standby; Step two: mix D40 de-aromatic solvent oil, D60 de-aromatic solvent oil and aromatic oil uniformly according to the designed material ratio to prepare the old material activator, and store it at room temperature for standby; Step three: put the asphalt pavement recycling material in rich oil state of each size range, the asphalt pavement recycling material in lean oil state of each size range, and the mineral powder into the oven respectively for drying treatment, and then take them out from the oven respectively after the drying treatment is completed, and cool them to room temperature naturally for standby; Step four: put the asphalt pavement recycling material in rich oil state of each size range into the first mixing pot, and stir it with the stirrer; put the asphalt pavement recycling material in lean oil state of each size range into the second mixing pot, and stir it with the stirrer; Step five: add part of the old material activator into the first mixing pot, and continue to stir it with the stirrer; add the remaining old material activator into the second mixing pot, and continue to stir it with the stirrer; after the stirring is completed, transfer all the substances in the second mixing pot into the first mixing pot; Step six: add the dilution asphalt into the first mixing pot, and continue to stir it with the stirrer; Step seven: add the mineral powder into the first mixing pot, and continue to stir it with the stirrer, and then the full RAP cold recycled asphalt mixture based on a small amount of new asphalt can be prepared after the stirring is completed.

2. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 1, wherein: The asphalt pavement recycling material is composed of asphalt pavement recycling material in rich oil state and asphalt pavement recycling material in lean oil state, and the mass percentage of the asphalt pavement recycling material in rich oil state and the asphalt pavement recycling material in lean oil state in the asphalt pavement recycling material is 50%.

3. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 2, wherein: The asphalt pavement recycling material in rich oil state includes two size ranges, 3-5mm and 0-3mm, and the mass percentage of each size range in the asphalt pavement recycling material in rich oil state is 70-80wt% of 3-5mm and 20-30wt% of 0-3mm.

4. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 3, wherein: The lean oil state asphalt pavement recycling material includes five particle size grades, 19-21.5 mm, 16-19 mm, 13.2-16 mm, 9.5-13.2 mm and 4.75-9.5 mm, and the mass percentage of each particle size grade in the lean oil state asphalt pavement recycling material is 5-8 wt% for the particle size 19-21.5 mm, 12-18 wt% for the particle size 16-19 mm, 6-10 wt% for the particle size 13.2-16 mm, 17-23 wt% for the particle size 9.5-13.2 mm, and 48-52 wt% for the particle size 4.75-9.5 mm.

5. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 4, wherein: The mass percentage of each substance in the dilution asphalt is 65-70 wt% for the base asphalt, 2-4 wt% for the SBS modifier, 0.2-0.5 wt% for the anti-stripping agent, 25-28 wt% for the diluent, and 2-3 wt% for the aromatic oil; the diluent is a mixture of D40 de-aromatic solvent oil and D60 de-aromatic solvent oil, and the mass percentage of each substance in the diluent is 30-50 wt% for the D40 de-aromatic solvent oil and 50-70 wt% for the D60 de-aromatic solvent oil.

6. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 5, wherein: The base asphalt is No. 70 base asphalt; the SBS modifier is linear SBS modifier; the anti-stripping agent is non-amine anti-stripping agent, which is any one or several of polyphosphoric acid, phosphate ester and nitrogen-containing complex; The D40 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatic hydrogenation refining and fractionation of straight-run distillate oil, hydrocracking distillate oil or low-sulfur straight-run aviation kerosene as raw material, with a distillation range of 150-200℃, a closed flash point of 40-50℃, an aromatic content of less than 0.03 wt%, a sulfur content of less than 0.2 mg / kg, and a saturated hydrocarbon content of more than 99.9%; The D60 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatic hydrogenation refining and fractionation of straight-run distillate oil, hydrocracking distillate oil or low-sulfur straight-run aviation kerosene as raw material, with a distillation range of 180-230℃, a closed flash point of 60-70℃, an aromatic content of less than 0.03 wt%, a sulfur content of less than 0.2 mg / kg, and a saturated hydrocarbon content of more than 99.9%; The flash point of the aromatic oil is not less than 200℃, the density is 0.99-1.02 g / cm 3 , the kinematic viscosity at 100℃ is 15-22 mm 2 / s.

7. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 6, wherein: The mass percentage of each substance in the old material activator is 40-45 wt% for the D40 de-aromatic solvent oil, 40-45 wt% for the D60 de-aromatic solvent oil, and 10-20 wt% for the aromatic oil.

8. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 7, wherein: The D40 de-aromatic solvent oil is obtained by deep desulfurization and de-aromatic hydrogenation refining and fractionation of straight-run distillate oil, hydrocracking distillate oil or low-sulfur straight-run aviation kerosene as raw material, with a distillation range of 150-200℃, a closed flash point of 40-50℃, an aromatic content of less than 0.03 wt%, a sulfur content of less than 0.2 mg / kg, and a saturated hydrocarbon content of more than 99.9%; The D60 de-aromatic solvent oil is prepared by using straight-run distillate oil, hydrocracking distillate oil or low-sulfur straight-run aviation kerosene as raw material, deep desulfurization and de-aromatic hydrofining and then fractionation, with a distillation range of 180-230 DEG C, a closed flash point of 60-70 DEG C, an aromatic content of less than 0.03wt%, a sulfur content of less than 0.2mg / kg and a saturated hydrocarbon content of more than 99.9%; The flash point of the aromatic oil is not less than 200℃, the density is 0.99-1.02 g / cm 3 , the kinematic viscosity at 100℃ is 15-22 mm 2 / s.

9. The micro-new bituminous based full RAP cold recycled asphalt mixture as claimed in claim 8, wherein: In step one, the preparation method of the diluted asphalt comprises the following steps in sequence, Step (1): according to the designed material ratio, the base asphalt, SBS modifier, anti-stripping agent, D40 de-aromatic solvent oil, D60 de-aromatic solvent oil and aromatic oil are weighed; Step (2): the base asphalt is put into a container, and then the container containing the base asphalt is put into an oven for heating, the heating temperature is 100-120 DEG C, and the heating time is 1-2h; Step (3): after the heating is completed, the container containing the base asphalt is taken out from the oven, the SBS modifier is added into the container, and then the container containing the base asphalt and the SBS modifier is placed on an electromagnetic oven for heating, while stirring and temperature rising, until the base asphalt and the SBS modifier are completely mixed, the heating temperature is increased to 160-170 DEG C, and the heating time is 15-20min; Step (4): the container containing the base asphalt and the SBS modifier is put into an oil bath pot, and high-speed shearing instrument is used for shearing and stirring, so that the SBS modified asphalt is prepared, the temperature of the oil bath pot is 160-170 DEG C, the shearing speed is 5000-6000r / min, and the shearing and stirring time is 0.5-1h; Step (5): the temperature of the oil bath pot is reduced to 100-120 DEG C, then the D60 de-aromatic solvent oil is added while stirring by using a stirrer, the stirring time is 15-20min, so that the SBS modified asphalt and the D60 de-aromatic solvent oil are completely mixed, the temperature of the oil bath pot is continuously reduced to 60-80 DEG C, then the D40 de-aromatic solvent oil is added while stirring by using the stirrer, the stirring time is 15-20min, so that the D40 de-aromatic solvent oil is completely mixed; Step (6): the temperature of the oil bath pot is kept unchanged, the stirring is continuously carried out by using the stirrer, the aromatic oil is added while stirring, and the stirring is carried out until the aromatic oil is completely mixed, the temperature of the oil bath pot is 60-80 DEG C, and the stirring time is 15-20min; Step (7): the temperature of the oil bath pot is kept unchanged, the stirring is continuously carried out by using the stirrer, the anti-stripping agent is added while stirring, and the stirring is carried out until the anti-stripping agent is completely mixed, the temperature of the oil bath pot is 60-80 DEG C, the stirring time is 15-20min, and after the stirring is completed, the diluted asphalt is prepared. 10.The micro-new asphalt based full RAP cold recycled asphalt mixture according to claim 9, wherein: In step three, the drying temperature of the asphalt pavement recycling materials in each size range in oil-rich state, the asphalt pavement recycling materials in each size range in oil-poor state and the mineral powder is 100-110 DEG C, and the drying time is 1-2h. In step four, the asphalt pavement recycling materials of each grade particle size in oil-rich state are put into the first mixing kettle for stirring, and the asphalt pavement recycling materials of each grade particle size in oil-poor state are put into the second mixing kettle for stirring, the stirring temperature is normal temperature, the stirring speed is 70-100 r / min, and the stirring time is 60-90 s; In step five, 70-80% of the old material activator is added into the first mixing kettle, and 20-30% of the old material activator is added into the second mixing kettle, the stirring temperature is normal temperature, the stirring speed is 70-100 r / min, and the stirring time is 60-90 s; In step six, the diluted asphalt is added into the first mixing kettle for stirring, the stirring temperature is normal temperature, the stirring speed is 70-100 r / min, and the stirring time is 60-90 s; in step seven, the mineral powder is added into the first mixing kettle for stirring, the stirring temperature is normal temperature, the stirring speed is 70-100 r / min, and the stirring time is 60-90 s.

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