Emulsified asphalt cold recycling asphalt pavement material, preparation method and application thereof

Abstract

The application provides an emulsified asphalt cold recycling asphalt pavement material, a preparation method and application thereof, and belongs to the technical field of cement-based modified asphalt pavement materials. The preparation method of the emulsified asphalt cold recycling asphalt pavement material is simple and easy to operate, realizes high-mixing application of RAP, and does not need heating and mixing treatment; the preparation cost is low, clean production is realized, and the method is suitable for large-area popularization. The emulsified asphalt cold recycling asphalt pavement material is a product composed of medium-grained modified emulsified asphalt cold recycling mixture as a middle surface layer material and coarse-grained ordinary emulsified asphalt cold recycling mixture as a lower surface layer material. The overall performance is excellent, and the emulsified asphalt cold recycling asphalt pavement material has strong pavement performance and crack resistance. The emulsified asphalt cold recycling asphalt pavement material can effectively replace widely used lower surface layer and middle surface layer hot-mixed asphalt mixtures in pavement surface layer structures, the formed asphalt pavement surface layer structure has strong pavement performance, and makes a positive contribution to resource utilization of road solid wastes.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cement-based modified asphalt pavement materials, and particularly relates to an emulsified asphalt cold recycling asphalt pavement material, a preparation method and application thereof. BACKGROUND

[0002] At present, the amount of road solid waste is huge and increases rapidly every year; the recycling rate of the road solid waste is low, and the resource utilization rate is not high. In the prior art, the road solid waste is usually treated by simple landfill and open-air stacking; this treatment method not only occupies a large amount of land area, but also causes comprehensive pollution of water, soil and air, and has environmental safety hazards.

[0003] The road solid waste can be converted into RAP (recycled asphalt mixture) through recycling processing, recycling utilization or other measures, and the RAP is applied to the asphalt pavement surface layer structure, which has the advantages of construction at normal temperature, no environmental pollution, reduced construction cost and high RAP utilization rate. However, in the prior art, the asphalt pavement material obtained by using the RAP has poor performance and weak crack resistance, which has limitations in the application of the asphalt pavement surface layer structure; if the performance required for the application in the asphalt pavement surface layer structure is met, the amount of RAP added is usually reduced and a large amount of new aggregate is introduced in the prior art, which is not conducive to the resource utilization of the road solid waste. SUMMARY

[0004] The main purpose of the application is to provide an emulsified asphalt cold recycling asphalt pavement material, a preparation method and application thereof, and to solve the problems of poor pavement performance, weak crack resistance and low resource utilization rate of the existing recycled asphalt pavement material.

[0005] To achieve the above purpose, the application provides a preparation method of an emulsified asphalt cold recycling asphalt pavement material, which comprises the following steps:

[0006] A coarse-grained ordinary emulsified asphalt cold recycling mixture is provided; the coarse-grained ordinary emulsified asphalt cold recycling mixture comprises ordinary emulsified asphalt for cold recycling.

[0007] A medium-grained modified emulsified asphalt cold recycling mixture is provided; the medium-grained modified emulsified asphalt cold recycling mixture comprises SBS modified emulsified asphalt for cold recycling.

[0008] The coarse-grained ordinary emulsified asphalt cold recycling mixture and the medium-grained modified emulsified asphalt cold recycling mixture are used in combination to obtain an emulsified asphalt cold recycling asphalt pavement material.

[0009] The cold regeneration ordinary emulsified asphalt and the cold regeneration SBS modified emulsified asphalt both comprise a cold regeneration emulsifier.

[0010] The first composition comprises two or more of a tallow-based primary amine, a hydrogenated tallow-based primary amine, a coconut oil-based primary amine, an oleyl primary amine, a tall oil primary amine, and an alkyl imidazoline acetate.

[0011] The second composition comprises two or more of a polyethyleneimine (PEI), an alkylphenol polyoxyethylene ether, a fatty alcohol polyoxyethylene ether, and a non-ionic polyacrylamide.

[0012] The third composition comprises one or more of an organosilane coupling agent, a fatty alcohol polyoxyethylene ether, a fatty acid polyoxyethylene ester, and a polyether-modified silicone oil.

[0013] Further, the coarse-grained ordinary emulsified asphalt cold regeneration mixture further comprises first new aggregate, coarse RAP, fine RAP, water, cement, and mineral powder; the coarse-grained ordinary emulsified asphalt cold regeneration mixture comprises, by mass fraction, 0-20 parts of the first new aggregate, 35-50 parts of the coarse RAP, 40-60 parts of the fine RAP, 3.0-5.0 parts of the cold regeneration ordinary emulsified asphalt, 2-5 parts of the water, 1-2 parts of the cement, and 1-5 parts of the mineral powder.

[0014] The medium-grained modified emulsified asphalt cold regeneration mixture further comprises second new aggregate, coarse RAP, fine RAP, water, cement, and mineral powder; the medium-grained modified emulsified asphalt cold regeneration mixture comprises, by mass fraction, 0-20 parts of the second new aggregate, 30-45 parts of the coarse RAP, 45-65 parts of the fine RAP, 3.5-5.5 parts of the cold regeneration SBS modified emulsified asphalt, 3-6 parts of the water, 1-2 parts of the cement, and 1-5 parts of the mineral powder.

[0015] Further, the cold regeneration ordinary emulsified asphalt comprises, by mass fraction, 60-65 parts of base asphalt, 2.2-3.2 parts of the cold regeneration emulsifier, 34-38 parts of water, and 0.3-0.8 parts of hydrochloric acid.

[0016] The cold regeneration SBS modified emulsified asphalt comprises, by mass fraction, 60-65 parts of SBS modified asphalt, 1.0-2.0 parts of a mixing type SBS modified emulsifier, 1.0-2.0 parts of the cold regeneration emulsifier, 34-38 parts of water, 0.1-0.5 parts of a stabilizer, and 0.3-0.8 parts of hydrochloric acid.

[0017] Further, the pH value of the common emulsified asphalt for cold regeneration and the SBS modified emulsified asphalt for cold regeneration is 2-3.

[0018] Further, the first new aggregate is limestone material, and the size of the first new aggregate is 20-30mm; the second new aggregate is limestone material, and the size of the second new aggregate is 10-20mm.

[0019] Further, the size of the coarse RAP includes two grades of 8-16mm and 16-25mm; and the size of the fine RAP is 0-8mm.

[0020] Further, the cement is a silicate retarding cement; and the mineral powder is limestone mineral powder, and the size of the limestone mineral powder is a 0.075mm screen passing rate of >75%.

[0021] Further, the combination is used in the following manner: the coarse-grained common emulsified asphalt cold regeneration mixture is laid flat as a lower layer; and the medium-grained modified emulsified asphalt cold regeneration mixture is laid flat as a middle surface layer on the upper side of the lower layer; wherein the thickness of the lower layer is ≥ the thickness of the middle surface layer.

[0022] The application further provides an emulsified asphalt cold regeneration asphalt pavement material prepared by the preparation method of the emulsified asphalt cold regeneration asphalt pavement material.

[0023] The application further provides an application of the emulsified asphalt cold regeneration asphalt pavement material in an asphalt pavement surface layer structure, wherein the coarse-grained common emulsified asphalt cold regeneration mixture in the emulsified asphalt cold regeneration asphalt pavement material is used as raw material to lay a lower layer structure of the asphalt pavement surface layer structure.

[0024] The medium-grained modified emulsified asphalt cold regeneration mixture in the emulsified asphalt cold regeneration asphalt pavement material is used as raw material to lay a middle surface layer structure of the asphalt pavement surface layer structure.

[0025] The SMA-13 asphalt mixture is used as raw material to lay a top surface layer structure of the asphalt pavement surface layer structure.

[0026] The thickness of the top surface layer structure, the middle surface layer structure and the lower layer structure is 3-5cm, 8-14cm and 10-16cm respectively.

[0027] Compared with the prior art, the application has at least the following advantages:

[0028] The preparation method of the emulsified asphalt cold regeneration asphalt pavement material is simple and easy to operate, realizes high-mixing application of RAP, and does not need heating and mixing treatment; the preparation cost is low, realizes clean production, and is suitable for large-area promotion.

[0029] The emulsified asphalt cold recycling asphalt pavement material provided by the application is a product composed of middle-grained modified emulsified asphalt cold recycling mixture as middle surface layer material and coarse-grained ordinary emulsified asphalt cold recycling mixture as lower surface layer material. The emulsified asphalt cold recycling asphalt pavement material can be applied to asphalt pavement surface layer structure; the splitting strength thereof is ≥0.8 MPa, the freeze-thaw splitting strength ratio is ≥80%, and the dynamic stability is ≥9000 times·mm -1 ; the overall performance is excellent, and the pavement performance and crack resistance are strong.

[0030] The emulsified asphalt cold recycling asphalt pavement material provided by the application can be applied to asphalt pavement surface layer structure as middle and lower surface layer structure, combined with SMA-13 asphalt mixture to construct upper, middle and lower three-layer surface layer structure; can effectively replace the widely used lower surface layer and middle surface layer hot-mixed asphalt mixture in pavement surface layer structure, and the formed asphalt pavement surface layer structure has strong pavement performance; and makes positive contribution to the resource utilization of road solid waste. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0032] Figure 1 The asphalt pavement surface layer structure provided by the application is shown in the figure;

[0033] Figure 2 The gradation curve of the middle-grained modified emulsified asphalt cold recycling mixture in embodiment 2 of the application is shown in the figure;

[0034] Figure 3 The gradation curve of the coarse-grained ordinary emulsified asphalt cold recycling mixture in embodiment 2 of the application is shown in the figure;

[0035] Figure 4 The flowchart of the preparation method of the emulsified asphalt cold recycling asphalt pavement material provided by the application is shown in the figure.

[0036] The implementation, functional features and advantages of the application will be further described with reference to the drawings. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work, fall within the protection scope of the present application.

[0038] In addition, the technical solutions among various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it. When the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0039] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified by the present application, both endpoints of each numerical range and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application are consistent with the mastery of the prior art by those skilled in the art and the description of the present application. Any method, equipment and material of the prior art similar or equivalent to the method, equipment and material described in the embodiments of the present application can also be used to realize the present application.

[0040] In order to solve the problems of poor pavement performance, weak crack resistance, or low road resource utilization rate of the existing recycled asphalt pavement material, the present application provides a preparation method of emulsified asphalt cold recycled asphalt pavement material, comprising the following steps:

[0041] A coarse-grained ordinary emulsified asphalt cold recycled mixture is provided; the coarse-grained ordinary emulsified asphalt cold recycled mixture includes ordinary emulsified asphalt for cold recycling. It should be noted that the coarse-grained ordinary emulsified asphalt cold recycled mixture refers to an emulsified asphalt cold recycled mixture with a maximum particle size of usually 37.5 mm.

[0042] A medium-grained modified emulsified asphalt cold recycled mixture is provided; the medium-grained modified emulsified asphalt cold recycled mixture includes 3.0-5.0 parts of SBS modified emulsified asphalt for cold recycling. It should be noted that the medium-grained modified emulsified asphalt cold recycled mixture refers to an emulsified asphalt cold recycled mixture with a maximum particle size of usually 26.5 mm.

[0043] The coarse-grained ordinary emulsified asphalt cold recycled mixture and the medium-grained modified emulsified asphalt cold recycled mixture are used in combination to obtain an emulsified asphalt cold recycled asphalt pavement material.

[0044] Among the ordinary emulsified asphalt for cold recycling and the SBS modified emulsified asphalt for cold recycling, both include an emulsifier for cold recycling; the emulsifier for cold recycling includes a first composition with a proportion ≥60%, a second composition with a proportion ≥10% and a third composition with a proportion ≥5%.

[0045] The first composition includes two or more of a tallow-based primary amine, a hydrogenated tallow-based primary amine, a coconut-based primary amine, an oleyl-based primary amine, a tall oil primary amine, and an alkyl imidazoline acetate.

[0046] The second composition includes two or more of a polyethyleneimine (PEI), an alkylphenol polyoxyethylene ether, a fatty alcohol polyoxyethylene ether, and a non-ionic polyacrylamide.

[0047] The third composition includes one or more of an organosilane coupling agent, a fatty alcohol polyoxyethylene ether, a fatty acid polyoxyethylene ester, and a polyether-modified silicone oil.

[0048] Optionally, the total incorporation amount of the RAP is ≥ 70%; optionally, the total incorporation amount of the RAP is ≥ 75%.

[0049] The preparation method of the emulsified asphalt cold recycled asphalt pavement material provided by the application is simple and easy to operate, realizes high incorporation amount application of the RAP, and does not need to be heated and mixed for processing; the preparation cost is low, clean production is realized, and the application is suitable for large-area promotion.

[0050] Further, the coarse-grained ordinary emulsified asphalt cold recycled mixture further includes first new aggregate, coarse RAP, fine RAP, water, cement, and mineral powder; the coarse-grained ordinary emulsified asphalt cold recycled mixture includes, in mass parts, 0-20 parts of first new aggregate, 35-50 parts of coarse RAP, 40-60 parts of fine RAP, 3.0-5.0 parts of ordinary emulsified asphalt for cold recycling, 2-5 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder. Optionally, the coarse-grained ordinary emulsified asphalt cold recycled mixture includes, in mass parts, 35-50 parts of coarse RAP, 40-60 parts of fine RAP, 3.0-5.0 parts of ordinary emulsified asphalt for cold recycling, 2-5 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder. Optionally, the coarse-grained ordinary emulsified asphalt cold recycled mixture includes, in mass parts, 1-20 parts of first new aggregate, 35-50 parts of coarse RAP, 40-60 parts of fine RAP, 3.0-5.0 parts of ordinary emulsified asphalt for cold recycling, 2-5 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder.

[0051] Specifically, the coarse-grained ordinary emulsified asphalt cold recycled mixture is obtained in the following manner: first, the first new aggregate, coarse RAP, part of the water, and part of the ordinary emulsified asphalt for cold recycling are subjected to first mixing treatment to obtain coarse-grained first mixed material; the remaining water is used to wet the fine RAP to obtain pre-wetted fine RAP; then the pre-wetted fine RAP and the remaining ordinary emulsified asphalt for cold recycling are added to the coarse-grained first mixed material, and second mixing treatment is performed to obtain coarse-grained second mixed material; finally, cement and mineral powder are added to the coarse-grained second mixed material, and third mixing treatment is performed to obtain the coarse-grained ordinary emulsified asphalt cold recycled mixture. Preferably, the first mixing treatment, the second mixing treatment, and the third mixing treatment are all mixing in a mixing kettle. Optionally, the mixing time of the first mixing treatment, the second mixing treatment, and the third mixing treatment is 60-120s.

[0052] The medium-grained modified emulsified asphalt cold recycled mixture further includes second new aggregate, coarse RAP, fine RAP, water, cement, and mineral powder; the medium-grained modified emulsified asphalt cold recycled mixture includes, by mass fraction, 0-20 parts of second new aggregate, 30-45 parts of coarse RAP, 45-65 parts of fine RAP, 3.5-5.5 parts of SBS modified emulsified asphalt for cold recycling, 3-6 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder. Optionally, the medium-grained modified emulsified asphalt cold recycled mixture includes, by mass fraction, 35-50 parts of coarse RAP, 40-60 parts of fine RAP, 3.0-5.0 parts of SBS modified emulsified asphalt for cold recycling, 2-5 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder. Optionally, the medium-grained modified emulsified asphalt cold recycled mixture includes, by mass fraction, 1-20 parts of second new aggregate, 30-45 parts of coarse RAP, 45-65 parts of fine RAP, 3.5-5.5 parts of SBS modified emulsified asphalt for cold recycling, 3-6 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder.

[0053] Specifically, the medium-grained modified emulsified asphalt cold recycled mixture is obtained in the following manner: first, the second new aggregate, coarse RAP, part of the water, and part of the SBS modified emulsified asphalt for cold recycling are subjected to fourth mixing treatment to obtain medium-grained fourth mixed material; the remaining water is used to wet the fine RAP to obtain pre-wetted fine RAP; then the pre-wetted fine RAP and the remaining SBS modified emulsified asphalt for cold recycling are added to the medium-grained fourth mixed material, and fifth mixing treatment is performed to obtain medium-grained fifth mixed material; finally, cement and mineral powder are added to the medium-grained fifth mixed material, and sixth mixing treatment is performed to obtain the medium-grained modified emulsified asphalt cold recycled mixture. Preferably, the fourth mixing treatment, the fifth mixing treatment, and the sixth mixing treatment are all mixing in a mixing kettle. Optionally, the mixing time of the fourth mixing treatment, the fifth mixing treatment, and the sixth mixing treatment is 60-120s.

[0054] Further, the cold recycling ordinary emulsified asphalt comprises, by mass fraction, 60-65 parts of base asphalt, 2.2-3.2 parts of cold recycling emulsifier, 34-38 parts of water, and 0.3-0.8 parts of hydrochloric acid.

[0055] The cold recycling SBS modified emulsified asphalt comprises, by mass fraction, 60-65 parts of SBS modified asphalt, 1.0-2.0 parts of mixing type SBS modified emulsifier, 1.0-2.0 parts of cold recycling emulsifier, 34-38 parts of water, 0.1-0.5 parts of stabilizer, and 0.3-0.8 parts of hydrochloric acid. Preferably, the mixing type SBS modified emulsifier is a slow-cracking mixing type SBS modified emulsifier produced by Tianjin Kangzewei Technology Co., Ltd. Optionally, the stabilizer comprises one or more of ammonium chloride, potassium chloride, sodium chloride, and polyvinyl alcohol.

[0056] Further, the pH values of the cold recycling ordinary emulsified asphalt and the cold recycling SBS modified emulsified asphalt are both 2-3. Specifically, only after being dissolved in water and carrying a positive charge, the emulsifier molecules can effectively wrap the surface of the tiny particles of the molten asphalt to form a positively charged interface film, thereby preventing the asphalt particles from re-aggregating through the charge repulsion effect, and thus achieving stable emulsification. If the acid is not adjusted, the emulsifiers cannot be fully dissolved and ionized, and the emulsification efficiency will be greatly reduced, or even lead to emulsification failure.

[0057] Further, the first new aggregate is of limestone material, and the specification of the first new aggregate is 20-30 mm; the second new aggregate is of limestone material, and the specification of the second new aggregate is 10-20 mm.

[0058] Further, the specification of the coarse RAP includes two grades of 8-16 mm and 16-25 mm; and the specification of the fine RAP is 0-8 mm. It should be noted that, in the field, the specification of the RAP is limited, wherein 8-16 mm represents RAP with a particle size greater than 8 mm and less than or equal to 16 mm; 16-25 mm represents RAP with a particle size greater than 16 mm and less than or equal to 25 mm; and 0-8 mm represents RAP with a particle size greater than 0 mm and less than or equal to 8 mm.

[0059] Further, the cement is a silicate retarding cement; and the mineral powder is limestone mineral powder with a specification of 0.075 mm screen passing rate >75%.

[0060] Further, the combined use is as follows: the coarse-grained ordinary emulsified asphalt cold recycling mixture is used as the lower layer and is laid flat; and the medium-grained modified emulsified asphalt cold recycling mixture is used as the middle surface layer and is laid flat on the upper side of the lower layer; wherein the thickness of the lower layer is ≥ the thickness of the middle surface layer.

[0061] The application further provides a preparation method of the emulsified asphalt cold recycling asphalt pavement material.

[0062] The emulsified asphalt cold recycling asphalt pavement material comprises a medium-grained modified emulsified asphalt cold recycling mixture as a middle surface layer material and a coarse-grained ordinary emulsified asphalt cold recycling mixture as a lower surface layer material. -1 The emulsified asphalt cold recycling asphalt pavement material has excellent overall performance, high pavement performance and high crack resistance.

[0063] The application further provides an application of the emulsified asphalt cold recycling asphalt pavement material in a surface layer structure of an asphalt pavement.

[0064] The medium-grained modified emulsified asphalt cold recycling mixture in the emulsified asphalt cold recycling asphalt pavement material is used as raw material to pave a middle surface layer structure of the asphalt pavement.

[0065] The SMA-13 asphalt mixture is used as raw material to pave a top surface layer structure of the asphalt pavement.

[0066] The thicknesses of the top surface layer structure, the middle surface layer structure and the lower surface layer structure are 3-5 cm, 8-14 cm and 10-16 cm respectively.

[0067] The emulsified asphalt cold recycling asphalt pavement material can be used as a middle and lower surface layer structure to construct a three-layer surface layer structure in combination with the SMA-13 asphalt mixture, and can effectively replace the widely used hot-mixed asphalt mixture for the lower surface layer and the middle surface layer of the surface layer structure of the asphalt pavement.

[0068] The following is a specific example of the application:

[0069] Example 1

[0070] (1) Preparation of ordinary emulsified asphalt for cold recycling

[0071] 63 parts of base asphalt, 2.5 parts of emulsifier for cold recycling, 34.0 parts of water and 0.5 parts of hydrochloric acid are emulsified by a mixing kettle to obtain ordinary emulsified asphalt for cold recycling.

[0072] The emulsifier for cold regeneration is composed of 75% of a first composition (50% hydrogenated tallow-based primary amine, 20% tallow-based primary amine, 5% tall oil primary amine) + 15% of a second composition (12% polyethylene imine PEI, 3% non-ionic polyacrylamide) + 10% of a third composition (7% fatty alcohol polyoxyethylene ether, 3% organic silane coupling agent).

[0073] (2) Preparation of SBS modified emulsified asphalt for cold regeneration

[0074] 63 parts of SBS modified asphalt, 1.5 parts of mixing type SBS modified emulsifier (slow cracking mixing type SBS modified emulsifier produced by Tianjin Kangzewei Technology Co., Ltd.), 1.3 parts of emulsifier for cold regeneration, 33.2 parts of water, 0.3 parts of sodium chloride and 0.5 parts of hydrochloric acid are emulsified by a mixing kettle to obtain SBS modified emulsified asphalt for cold regeneration.

[0075] The emulsifier for cold regeneration is composed of 75% of a first composition (50% hydrogenated tallow-based primary amine, 20% tallow-based primary amine, 5% tall oil primary amine) + 15% of a second composition (12% polyethylene imine PEI, 3% non-ionic polyacrylamide) + 10% of a third composition (7% fatty alcohol polyoxyethylene ether, 3% organic silane coupling agent).

[0076] Example 2

[0077] Preparation of emulsified asphalt cold regeneration asphalt pavement material (coarse-grained ordinary emulsified asphalt cold regeneration mixture and medium-grained modified emulsified asphalt cold regeneration mixture are prepared respectively, and the two are used in combination to obtain)

[0078] (1) Preparation of coarse-grained ordinary emulsified asphalt cold regeneration mixture

[0079] The components of the coarse-grained ordinary emulsified asphalt cold regeneration mixture are provided, which include, by mass fraction, 12 parts of first new aggregate (20-30 mm), 23 parts of coarse RAP (16-25 mm), 20 parts of coarse RAP (8-16 mm), 42 parts of fine RAP (0-8 mm), 3 parts of mineral powder, 4.0 parts of ordinary emulsified asphalt for cold regeneration (prepared in Example 1), 2.8 parts of additional water and 1.5 parts of cement. The synthetic gradation curve is obtained according to 12 parts of first new aggregate (20-30 mm), 23 parts of coarse RAP (16-25 mm), 20 parts of coarse RAP (8-16 mm), 42 parts of fine RAP (0-8 mm) and 3 parts of mineral powder, and the corresponding gradation curve is plotted, as shown in Figure 2 It can be seen from Figure 2 that the synthetic gradation curve is between the upper limit curve and the lower limit curve of the gradation curve graph, and meets the gradation requirements.

[0080] The first new aggregate, coarse RAP (16-25 mm), coarse RAP (8-16 mm), part of water, and part of the cold recycling ordinary emulsified asphalt are first mixed in a mixing kettle for 60 s; then the pre-wetted fine RAP (the remaining water-wetted fine RAP) and the remaining cold recycling ordinary emulsified asphalt are mixed for 60 s; finally, cement and mineral powder are mixed for 60 s, and the coarse-grained ordinary emulsified asphalt cold recycling asphalt mixture is stirred, which is then used to form Marshall test pieces and rut test pieces, and the performance test results are recorded. The test item is marked as Example 2-(1).

[0081] (2) Preparation of medium-grained modified emulsified asphalt cold recycling mixture

[0082] The components of the medium-grained modified emulsified asphalt cold recycling asphalt mixture are provided, which include, by mass fraction, 12 parts of second new aggregate (10-20 mm), 18 parts of coarse RAP (16-25 mm), 20 parts of coarse RAP (8-16 mm), 47 parts of fine RAP (0-8 mm), 3 parts of mineral powder, 4.5 parts of SBS modified emulsified asphalt for cold recycling, 3.1 parts of additional water, and 1.5 parts of cement. The synthetic gradation curve is obtained according to 12 parts of second new aggregate (10-20 mm), 18 parts of coarse RAP (16-25 mm), 23 parts of coarse RAP (8-16 mm), 44 parts of fine RAP (0-8 mm), and 3 parts of mineral powder, and the corresponding gradation curve is plotted, as shown in FIG. 2. Figure 3 As can be seen from FIG. 2, the synthetic gradation curve is between the upper limit curve and the lower limit curve of the gradation curve graph, which meets the gradation requirements. Figure 3

[0083] The second new aggregate, coarse RAP (16-25 mm), coarse RAP (8-16 mm), part of water, and part of the cold recycling SBS modified emulsified asphalt are first mixed in a mixing kettle for 60 s; then the pre-wetted fine RAP (the remaining water-wetted fine RAP) and the remaining cold recycling SBS modified emulsified asphalt are mixed for 60 s; finally, cement and mineral powder are mixed for 60 s, and the medium-grained modified emulsified asphalt cold recycling mixture is stirred, which is then used to form Marshall test pieces and rut test pieces, and the performance test results are recorded. The test item is marked as Example 2-(2).

[0084] Comparative Example 1

[0085] The cold recycling ordinary emulsified asphalt prepared in reference to Example 1-(1) is prepared as follows. Compared with the cold recycling ordinary emulsified asphalt preparation steps in Example 1, only the composition ratio of the cold recycling emulsifier is changed, and the specific substances and ratios of the remaining components, the specific substances and ratios of the compositions in the cold recycling emulsifier are the same; specifically:

[0086] ​A, without 75% of the first composition, only 90% of the second composition, 10% of the third composition. The resulting comparative ordinary emulsified asphalt is named Comparative Example 1-A.

[0087] B, without 75% of the first composition, only 15% of the second composition, 85% of the third composition. The resulting comparative ordinary emulsified asphalt is named Comparative Example 1-B.

[0088] C, without 15% of the second composition, only 90% of the first composition, 10% of the third composition. The resulting comparative ordinary emulsified asphalt is named Comparative Example 1-C.

[0089] D, without 15% of the second composition, only 75% of the first composition, 25% of the third composition. The resulting comparative ordinary emulsified asphalt is named Comparative Example 1-D.

[0090] E, without 10% of the third composition, only 85% of the first composition, 15% of the second composition. The resulting comparative ordinary emulsified asphalt is named Comparative Example 1-E.

[0091] F, without 10% of the third composition, only 75% of the first composition, 25% of the second composition. The resulting comparative ordinary emulsified asphalt is named Comparative Example 1-F.

[0092] Analysis Example 1

[0093] The test items of the cold recycling ordinary emulsified asphalt of Example 1- (1) and the comparative ordinary emulsified asphalt of Comparative Examples 1-A to 1-F are subjected to emulsified asphalt performance testing. Among them, the test items include demulsification speed, Engler viscosity, evaporation residue index, adhesion to coarse aggregate and room temperature storage stability; the test steps and performance standards of specific performance testing are all referred to the relevant provisions of “Standard Test Methods for Asphalt and Asphalt Mixtures for Highway Engineering” (JTG E20-2011). The corresponding performance test results are shown in Table 1.

[0094] Table 1 Comparison of emulsified asphalt performance test results

[0095]

[0096] From Table 1, it can be seen that the emulsified asphalt performance test of the cold recycling ordinary emulsified asphalt of Example 1- (1) has excellent performance indicators, all of which meet the technical requirements in “Technical Specification for Highway Asphalt Pavement Recycling” (JTG T 5521-2019). Among Comparative Examples 1-A to 1-F, Comparative Examples 1-A and 1-B cannot complete the emulsification of asphalt, and among the remaining comparative ordinary emulsified asphalt that can complete asphalt emulsification, only Comparative Example 1-E meets the specification technical requirements.

[0097] Comparative Example 2

[0098] The coarse-grained ordinary emulsified asphalt cold recycling mixture prepared with reference to Example 2-(1) is prepared as follows. Compared with the coarse-grained ordinary emulsified asphalt cold recycling mixture preparation step in Example 2-(1), only the cold recycling ordinary emulsified asphalt therein is replaced with each comparative ordinary emulsified asphalt of Comparative Example 1-A to Comparative Example 1-F, and the other components and proportions are the same; specifically:

[0099] A, the coarse-grained ordinary emulsified asphalt mixture of Comparative Example 2-A is prepared by using Comparative Example 1-A.

[0100] B, the coarse-grained ordinary emulsified asphalt mixture of Comparative Example 2-B is prepared by using Comparative Example 1-B.

[0101] C, the coarse-grained ordinary emulsified asphalt mixture of Comparative Example 2-C is prepared by using Comparative Example 1-C.

[0102] D, the coarse-grained ordinary emulsified asphalt mixture of Comparative Example 2-D is prepared by using Comparative Example 1-D.

[0103] E, the coarse-grained ordinary emulsified asphalt mixture of Comparative Example 2-E is prepared by using Comparative Example 1-E.

[0104] F, the coarse-grained ordinary emulsified asphalt mixture of Comparative Example 2-F is prepared by using Comparative Example 1-F.

[0105] Analysis Example 2

[0106] The test items of the coarse-grained ordinary emulsified asphalt cold recycling mixture of Example 2-(1), the granular modified emulsified asphalt cold recycling mixture of Example 2-(2), and the coarse-grained comparative ordinary emulsified asphalt of Comparative Example 2-A to Comparative Example 2-F are subjected to mixture performance testing, and the test items include bulk relative density, void ratio, splitting strength, freeze-thaw splitting strength ratio, and dynamic stability; the test steps of the specific performance testing are all with reference to the relevant provisions of “Highway Engineering Asphalt and Asphalt Mixture Test Procedures” (JTGE20-2011). The corresponding performance test results are shown in Table 2.

[0107] Table 2 Comparison of performance test results of each mixture

[0108]

[0109] From Table 2, the volume index of the coarse-grained ordinary emulsified asphalt cold recycled asphalt mixture of Example 2-(1) and the medium-grained modified emulsified asphalt cold recycled asphalt mixture of Example 2-(2) meets the technical requirements in the Technical Specification for Asphalt Pavement Recycling (JTG T 5521-2019), and the mechanical indexes and road performance indexes are far superior to the technical requirements of the emulsified asphalt cold recycled asphalt mixture for the surface layer of the asphalt pavement, and the coarse-grained ordinary emulsified asphalt cold recycled asphalt mixture can completely replace the hot-mixed asphalt mixture for the middle and lower layers of the asphalt pavement. In Comparative Examples 2-A to 2-F, Comparative Examples 2-A, 2-B and 2-D failed to prepare the cold recycled mixture, and the performance indexes of the coarse-grained ordinary emulsified asphalt mixture prepared in the remaining examples were far lower than those of the coarse-grained ordinary emulsified asphalt cold recycled asphalt mixture of Example 2-(1).

[0110] Therefore, the medium-grained modified emulsified asphalt cold recycled mixture and the coarse-grained ordinary emulsified asphalt cold recycled mixture in the present application can be combined to form an emulsified asphalt cold recycled asphalt pavement material as a middle and lower layer structure, which completely replaces the hot-mixed asphalt mixture for the middle and lower layers of the asphalt pavement. The preparation method of the emulsified asphalt cold recycled asphalt pavement material is shown in the flowchart of Figure 4 Specifically, in the actual paving process of the asphalt pavement surface layer structure, the coarse-grained ordinary emulsified asphalt cold recycled mixture is used as a lower layer structure 3 (with a thickness of 10-16 cm) of the asphalt pavement surface layer structure (refer to Figure 1 ), the medium-grained modified emulsified asphalt cold recycled mixture is used as a middle layer structure 2 (with a thickness of 8-14 cm) of the asphalt pavement surface layer structure, and the SMA-13 asphalt mixture is used as a top layer structure 1 (with a thickness of 3-5 cm) of the asphalt pavement surface layer structure. The three layer materials are sequentially paved and compacted from bottom to top to form the asphalt pavement surface layer structure, which has strong road damage resistance.

[0111] In the above technical solution of the present application, the above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation or direct / indirect application in other related technical fields based on the technical concept of the present application and the content of the present application are included in the patent protection scope of the present application.

Claims

1. A method for preparing emulsified asphalt cold recycled asphalt pavement material, characterized in that, Including the following steps: A coarse-grained ordinary emulsified asphalt cold recycling mixture is provided; the coarse-grained ordinary emulsified asphalt cold recycling mixture includes ordinary emulsified asphalt for cold recycling; Medium-grained modified emulsified asphalt cold recycling mixture is provided; the medium-grained modified emulsified asphalt cold recycling mixture includes SBS modified emulsified asphalt for cold recycling; The coarse-grained ordinary emulsified asphalt cold recycled mixture and the medium-grained modified emulsified asphalt cold recycled mixture are used in combination to obtain emulsified asphalt cold recycled asphalt pavement material. The ordinary emulsified asphalt for cold recycling and the SBS modified emulsified asphalt for cold recycling both include a cold recycling emulsifier; the cold recycling emulsifier includes a first composition with a proportion of ≥60%, a second composition with a proportion of ≥10%, and a third composition with a proportion of ≥5%. The first composition consists of tallow-based primary amine, hydrogenated tallow-based primary amine, and tallow-based primary amine; The second composition consists of polyethyleneimine (PEI) and nonionic polyacrylamide; The third composition consists of an organosilane coupling agent and a fatty alcohol polyoxyethylene ether.

2. The method for preparing emulsified asphalt cold recycled asphalt pavement material according to claim 1, characterized in that, The coarse-grained ordinary emulsified asphalt cold recycled mixture further includes a first new aggregate, coarse RAP, fine RAP, water, cement, and mineral powder; the coarse-grained ordinary emulsified asphalt cold recycled mixture, by weight, includes: 0-20 parts of the first new aggregate, 35-50 parts of the coarse RAP, 40-60 parts of the fine RAP, 3.0-5.0 parts of the ordinary emulsified asphalt for cold recycling, 2-5 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder; The medium-grained modified emulsified asphalt cold recycled mixture further includes a second new aggregate, coarse RAP, fine RAP, water, cement, and mineral powder; the medium-grained modified emulsified asphalt cold recycled mixture, by weight, includes: 0-20 parts of the second new aggregate, 30-45 parts of the coarse RAP, 45-65 parts of the fine RAP, 3.5-5.5 parts of the SBS modified emulsified asphalt for cold recycling, 3-6 parts of water, 1-2 parts of cement, and 1-5 parts of mineral powder.

3. The method for preparing emulsified asphalt cold recycled asphalt pavement material according to claim 1, characterized in that, The ordinary emulsified asphalt for cold recycling comprises, by weight: 60-65 parts base asphalt, 2.2-3.2 parts emulsifier for cold recycling, 33-38 parts water, and 0.3-0.8 parts hydrochloric acid; The SBS modified emulsified asphalt for cold recycling comprises, by weight: 60-65 parts of SBS modified asphalt, 1.0-2.0 parts of mixed-type SBS modified emulsifier, 1.0-2.0 parts of the emulsifier for cold recycling, 33-38 parts of water, 0.1-0.5 parts of stabilizer, and 0.3-0.8 parts of hydrochloric acid.

4. The method for preparing emulsified asphalt cold recycled asphalt pavement material according to claim 3, characterized in that, The pH value of both the ordinary emulsified asphalt used for cold recycling and the SBS modified emulsified asphalt used for cold recycling is 2-3.

5. The method for preparing emulsified asphalt cold recycled asphalt pavement material according to claim 2, characterized in that, The first new aggregate is made of limestone and has a size of 20-30mm; the second new aggregate is made of limestone and has a size of 10-20mm.

6. The method for preparing emulsified asphalt cold recycled asphalt pavement material according to claim 2, characterized in that, The coarse RAP specifications include two grades: 8~16mm and 16~25mm; the fine RAP specifications are 0~8mm.

7. The method for preparing emulsified asphalt cold recycled asphalt pavement material according to claim 2, characterized in that, The cement is silicate retarded cement; the mineral powder is limestone mineral powder, and the limestone mineral powder has a sieve passing rate of >75% on a 0.075mm sieve.

8. The method for preparing emulsified asphalt cold recycled asphalt pavement material according to claim 1, characterized in that, The combination is used as follows: the coarse-grained ordinary emulsified asphalt cold recycled mixture is laid as the lower layer and leveled; the medium-grained modified emulsified asphalt cold recycled mixture is laid as the middle layer on top of the lower layer and leveled; wherein the thickness of the lower layer is greater than or equal to the thickness of the middle layer.

9. An emulsified asphalt cold recycled asphalt pavement material prepared by the preparation method of the emulsified asphalt cold recycled asphalt pavement material according to any one of claims 1 to 8.

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