High-stability steel slag asphalt mixture and preparation method thereof

Abstract

The application belongs to the technical field of pavement materials, and particularly relates to a high-stability steel slag asphalt mixture and a preparation method thereof. The high-stability steel slag asphalt mixture comprises the following raw materials in parts by weight: 60-80 parts of coarse aggregate steel slag with a particle size greater than 2.36 mm, 40-60 parts of fine aggregate stone with a particle size less than 2.36 mm, 10-15 parts of modified mineral powder, 20-25 parts of No. 90 base asphalt, 15-30 parts of steel slag stabilizer and 0.4-0.5 parts of asphalt modifier. The stability of the steel slag asphalt mixture is greatly improved, and the durability of the pavement can be enhanced by using the mixture.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pavement materials, and particularly relates to a high-stability steel slag asphalt mixture and a preparation method thereof. BACKGROUND

[0002] Due to the continuous consumption of road construction, overexploitation of non-renewable natural stone causes serious and irreparable damage to the environment, so it is necessary to find alternative materials. Solid waste generated by industrial metallurgy, i.e., steel slag, is an ideal material because it is low in cost and has similar mineral composition to natural stone. Steel slag is a byproduct of industrial steelmaking, and China produces hundreds of millions of tons per year, but only 20% of this material is recycled; the remaining total amount exceeds 700 million tons, which is usually stacked or buried in landfills. Stacking steel slag not only occupies a large amount of land resources, but also produces dust, polluting the air; in addition, steel slag buried in landfills can seep heavy metal ions, polluting the soil and causing serious damage to the environment. Therefore, using steel slag instead of natural stone for road construction is a win-win method to solve the above problems. Steel slag has the advantages of rough surface, high strength and high wear resistance, and has good physical and mechanical properties, and can be used as aggregate in asphalt pavement.

[0003] However, unlike natural stone, steel slag contains an excess of free calcium oxide or / and free magnesium oxide on the surface. These free active ingredients will hydrate to generate Ca(OH)2, Mg(OH)2, etc. when in contact with water, which in turn causes volume expansion.

[0004] The pavement paved with ordinary conventional steel slag asphalt mixture is prone to cracking and other diseases after encountering water, thereby greatly affecting the water stability of the steel slag asphalt mixture and reducing the service life of the pavement, limiting the application of steel slag in asphalt pavement.

[0005] At present, the improvement of the stability of steel slag often adopts traditional heat warming method and natural accumulation and solidification method. The traditional heat warming method uses equipment with large volume, which needs to be specially built, and has high requirements for process operation. If the slag layer is not loosened in time during the treatment process, slagging phenomenon will occur, which has adverse effects on the treatment effect of steel slag. The natural accumulation and solidification method has a long treatment time and occupies a large area. SUMMARY

[0006] In order to improve the stability of the steel slag asphalt mixture and enhance the durability of the pavement, the application provides a high-stability steel slag asphalt mixture and a preparation method thereof.

[0007] The technical scheme of the application is as follows:

[0008] A high-stability steel slag asphalt mixture, comprising the following raw materials by weight: 60-80 parts of coarse aggregate steel slag with a particle size greater than 2.36 mm, 40-60 parts of fine aggregate stone with a particle size less than 2.36 mm, 10-15 parts of modified mineral powder, 20-25 parts of No. 90 base asphalt, 15-30 parts of steel slag stabilizer, and 0.4-0.5 parts of asphalt modifier.

[0009] In the high-stability steel slag asphalt mixture, the crushing value of the coarse aggregate steel slag is less than or equal to 20%, the solidity is less than or equal to 10%, the content of needles and flakes with a size greater than or equal to 9.5 mm is less than or equal to 6%, the content of weak particles is less than or equal to 3.5%, the abrasion value is less than or equal to 20%, and the adhesion to asphalt is greater than or equal to 6 levels.

[0010] The coarse aggregate steel slag is blast furnace steel slag, and the fine aggregate stone is at least one of andesite, granite or basalt. The andesite, granite or basalt fine aggregate is mixed with the blast furnace steel slag as alkaline aggregate, and the stability of the mixture is improved under the guarantee of the steel slag stabilizer.

[0011] In the high-stability steel slag asphalt mixture, the performance indicators of the blast furnace steel slag are as follows:

[0012] The apparent relative density of the 3-5 mm blast furnace steel slag is 3.365-3.380, the bulk relative density is 3.160-3.175, the water absorption is 2.0-2.3%, and the free calcium oxide content is 1.2-1.4%.

[0013] The apparent relative density of the 5-10 mm blast furnace steel slag is 3.330-3.340, the bulk relative density is 3.090-3.100, the water absorption is 1.8-2.1%, and the free calcium oxide content is 1.55-1.65%.

[0014] The apparent relative density of the 10-15 mm blast furnace steel slag is 3.295-3.3100, the bulk relative density is 3.050-3.150, the water absorption is 1.6-1.8%, and the free calcium oxide content is 2.0-2.3%.

[0015] The apparent relative density of the andesite is greater than or equal to 2.800, the sand equivalent is 70-85%, and the methylene blue value is 1.8-3.0 g / kg.

[0016] The apparent relative density of the granite is greater than or equal to 2.550, the sand equivalent is 80-90%, and the methylene blue value is 1.5-2.0 g / kg.

[0017] The apparent relative density of the basalt is greater than or equal to 2.730, the sand equivalent is 75-85%, and the methylene blue value is 2.3-2.8 g / kg.

[0018] In the application, the modified mineral powder in the high-stability steel slag asphalt mixture is titanium ester coupling agent GR-201 modified limestone mineral powder; the particle size of the steel slag stabilizer is 0.075-0.3 mm; and the asphalt modifier is warm-mixing agent LEADCAP. The titanium ester coupling agent GR-201 modified limestone mineral powder as a filler can significantly improve the adhesion of asphalt and aggregate, and reduce the amount of asphalt, and has an oil absorption effect.

[0019] In the application, the aggregate gradation range of the high-stability steel slag asphalt mixture is one of the following a, b and c:

[0020] a, the proportion of each grade of AC-13 gradation is:

[0021] 10-15 mm steel slag: 5-10 mm steel slag: 3-5 mm steel slag: 0-3 mm stone: modified mineral powder = 56-60: 10-14: 16-18: 9: 3; the amount of 90# base asphalt is 4.6-4.8 wt%.

[0022] b, the proportion of each grade of SMA-13 gradation is:

[0023] Modified mineral powder: 0-3 mm stone: 5-10 mm steel slag: 10-15 mm steel slag = 8-10: 10-14: 30-35: 44-48; the amount of 90# base asphalt is 5.9-6.1 wt%; and lignin fiber is further included, and the amount is 3.3-3.5 wt‰.

[0024] c, the proportion of each grade of SMA-5 gradation is:

[0025] Modified mineral powder: 0-3 mm stone: 3-5 mm steel slag = 8: 31: 59-63; the amount of 90# base asphalt is 6.1-6.3 wt%; and lignin fiber is further included, and the amount is 3.5-3.7 wt‰.

[0026] In the application, the steel slag stabilizer in the high-stability steel slag asphalt mixture is prepared by the following method:

[0027] (1) batching: FeO powder with a purity of 99.5% and an average particle size of 180-200 μm is mixed and ground with MgO powder with a purity of 99.9% and an average particle size of 0.2-0.25 μm to obtain a powder mixture; wherein the mass ratio of FeO powder to MgO powder is 21-22: 78-79;

[0028] (2) granulation: the powder mixture obtained in step (1) is pressed into a ball particle with a diameter of 7-9 mm and a weight of 0.3-0.5 g by using a press; the pressing pressure is 2-2.5 MPa; the pressing into a ball particle can increase the powder briquetting and promote sintering.

[0029] (3) primary sintering: the ball particle obtained in step (2) is sintered in a gas-tight electric furnace at a high-purity argon gas pressure of 6-10 atm and a temperature of 1770-1780 K for 24 hours;

[0030] (4) cooling, grinding and re-granulation: the ball obtained after the primary sintering in step (3) is cooled in the furnace at a rate of 300 K / h, and after cooling, the ball is taken out, crushed into powder and ground, and then re-granulated;

[0031] (5) secondary sintering: the ball obtained by re-granulation is sintered for the second time according to the conditions of the primary sintering in step (3) to obtain a steel slag stabilizer.

[0032] The steel slag stabilizer prepared by the method has higher purity, and the purity can reach 95-98%; the high-purity steel slag stabilizer is used in a steel slag asphalt mixture, which can greatly reduce the mass fraction of free components on the steel slag aggregate to 0.01-0.02 wt%.

[0033] In the present application, the high-stability steel slag asphalt mixture has a normal-temperature leakage loss of <0.1%; a 60℃ flying test loss of 6-7%; a dynamic stability test under the condition of 70℃ and 1.0 MPa for 4000-5000 times; a 50℃ Hamburg rutting test deformation of 3-4 mm; a freeze-thaw splitting strength ratio of 88-95%; and a low-temperature bending strain of 2900-3400 με.

[0034] The preparation method of the high-stability steel slag asphalt mixture comprises the following steps:

[0035] (1) preparation of warm-mixed asphalt: a bitumen modifier is added to No. 90 base bitumen, and stirring is carried out at a temperature of 130-150℃ and a rotation speed of 1000-1200 r / min for 10-12 min;

[0036] (2) stabilization and modification of coarse aggregate steel slag: the steel slag coarse aggregate is mixed with the steel slag stabilizer for 80-90 s at a mixing temperature of 140-150℃;

[0037] (3) mixture mixing: the stabilized and modified coarse aggregate steel slag is first mixed with fine aggregate stone for 90-120 s, then the warm-mixed asphalt obtained in step (1) is added and mixed for 90-100 s, and then modified mineral powder is added and mixed for 80-90 s after the end of the mixing; the mixing temperature is 145-150℃.

[0038] Based on the mixed mixture, if the mixing temperature is too high, the aging of asphalt will be accelerated, thereby affecting the fatigue performance of the subsequent mixture; however, if the mixing temperature is too low, the void ratio of the mixture will be affected, and the mixing will be insufficient.

[0039] In the application, the thickness of the warm-mixed asphalt film in the high-stability steel slag asphalt mixture preparation method is 6-8 mu.

[0040] The beneficial effects of the application are:

[0041] 1、The high-stability steel slag mixture of the application specifies that the mixing method is warm mixing, compared with the traditional hot mixing method, the application can improve the adhesion of steel slag aggregate and warm-mixed asphalt, guarantee the integrity and durability of subsequent rolling, and achieve energy saving. The temperature of the traditional hot-mixed mixture is between 170-200 DEG C, which consumes a lot of energy, and the measured temperature value fluctuates greatly during the mixing process, which cannot be accurately controlled, resulting in problems such as mixture aging or caking or reduced adhesion of asphalt and aggregate. Warm mixing can ensure that the aggregate and asphalt are mixed fully and uniformly, and the temperature is controlled in a reasonable range to prevent the steel slag stabilizer and fine aggregate attached to the surface of the steel slag aggregate from falling off due to high temperature, thereby improving the overall stability.

[0042] 2、The application specifies the preparation and material selection of steel slag stabilizer, warm-mixed asphalt and modified mineral powder in the high-stability steel slag mixture, and limits the selection of fine aggregate. By performing gradation design on the performance indicators of the high-stability steel slag mixture, the comprehensive road performance of the high-stability steel slag mixture is effectively guaranteed.

[0043] 3、The application solves the instability deformation disease caused by the insufficient water stability of the traditional steel slag asphalt mixture, effectively guarantees the integrity and durability of the road use effect, and has significant economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The figure is the gradation curve of the SMA-13 high-stability steel slag asphalt mixture in Example 1 of the application.

[0045] Figure 2 The figure is the gradation curve of the AC-13 high-stability steel slag asphalt mixture in Example 3 of the application. DETAILED DESCRIPTION

[0046] The technical solutions of the application will be described in detail below with reference to the drawings.

[0047] 1、The steel slag stabilizer used is prepared by the following method:

[0048] (1) Blending: FeO powder with a mass fraction of 21.71% and a purity of 99.5% and an average particle size of 180 μm is mixed and ground with MgO powder with a mass fraction of 78.29% and a purity of 99.9% and an average particle size of 0.2 μm to obtain a powder mixture;

[0049] (2) Granulation: The powder mixture obtained in step (1) is compressed into a pellet particle with a diameter of 8 mm and a weight of 0.4 g using a press; the compression pressure is 2 MPa; the pellet particle is compressed to increase the powder briquetting and promote sintering.

[0050] (3) First sintering: The pellet particle obtained in step (2) is sintered in a gas-tight electric furnace at 1773 K for 24 hours under a high-purity argon gas pressure of 10 atm;

[0051] (4) Cooling, grinding, and re-granulation: The pellet obtained after the first sintering in step (3) is cooled in the furnace at a rate of 300 K / h, and after cooling, the pellet is taken out, crushed into powder, ground, and re-granulated;

[0052] (5) Second sintering: The pellet obtained by re-granulation is sintered for the second time under the conditions of the first sintering in step (3) to obtain a steel slag stabilizer.

[0053] 2. The titanium ester coupling agent GR-201 used to modify the limestone powder: titanium ester coupling agent GR-201, an amphoteric compound, a slightly yellow clear liquid, with a density and flash point of 1.026 g / mL and 55°C at a temperature of 30°C, compatible with analytical pure anhydrous ethanol, analytical pure isopropyl alcohol and other organic additives, and its modification mechanism is as follows:

[0054]

[0055] The technical indicators of the titanium ester coupling agent GR-201 modified limestone powder are shown in Table 1:

[0056] Table 1

[0057]

[0058] 3. The technical indicators of the No. 90 base asphalt used are shown in Table 2:

[0059] Table 2

[0060]

[0061] Example 1 (SMA-13 high-stability steel slag asphalt mixture)

[0062] The high-stability steel slag asphalt mixture comprises the following raw materials in parts by weight: coarse aggregate high-temperature blast furnace slag with a particle size greater than 2.36 mm, 80 parts; fine aggregate granite with a particle size less than 2.36 mm, 60 parts; titanium ester coupling agent GR-201 modified limestone powder, 15 parts; No. 90 base asphalt, 25 parts; steel slag stabilizer, 25 parts; and asphalt warm-mixing agent LEADCAP, 0.5 part.

[0063] The indexes of the blast furnace slag are shown in Table 3.

[0064] Table 3

[0065] Test Index Steel Slag Aggregate Crushing Value (%) 18 Soundness (%) 8 Needle and Flake Content (> 9.5 mm, %) 3 Weak Particle Content (%) 2 Wear Value (%) 12 Adhesion to Asphalt (Grade) 7

[0066] The granite has an apparent relative density of 2.560, a sand equivalent of 83, and a methylene blue value of 1.8.

[0067] The SMA-13 high-stability steel slag asphalt mixture has the following proportions of each grade of aggregate in the aggregate grading:

[0068] The limestone powder: 0-3 mm granite: 5-10 mm blast furnace slag: 10-15 mm blast furnace slag = 8:10.5:34:47.5; the asphalt content is 5.9 wt%, and the lignin fiber content is 3.3 wt%.

[0069] The 5-10 mm blast furnace slag has an apparent relative density of 3.335, a bulk volume relative density of 3.090, a water absorption of 2.0%, and a free calcium oxide content of 1.58%.

[0070] The 10-15 mm blast furnace slag has an apparent relative density of 3.298, a bulk volume relative density of 3.056, a water absorption of 1.7%, and a free calcium oxide content of 2.1%.

[0071] The SMA-13 high-stability steel slag asphalt mixture has the following synthetic grading, as shown in Table 4:

[0072] The high-stability steel slag mixture grading described in this embodiment is shown in Table 4, wherein the initial selection is three gradings, namely, grading 1, grading 2, and grading 3, and finally, grading 2 is adopted.

[0073] Table 4

[0074]

[0075]

[0076] The preparation method of the high-stability steel slag asphalt mixture comprises the following steps:

[0077] (1) Preparation of warm mix asphalt: warm mix asphalt agent LEADCAP was added into No. 90 base asphalt, and stirred at 150℃ and 1000 rpm for 10 min;

[0078] (2) Stabilization and modification of coarse aggregate steel slag: 5-10 mm blast furnace steel slag was mixed with steel slag stabilizer for 30 s, and then 10-15 mm blast furnace steel slag was added and mixed for another 60 s; the mixing temperature was 140℃;

[0079] (3) Mixing of mixture: the stabilized and modified coarse aggregate steel slag and lignin fiber were mixed with fine aggregate granite for 90 s, and then the warm mix asphalt obtained in step (1) was added and mixed for 90 s, and modified mineral powder was added and mixed for another 80 s after the end of mixing; the mixing temperature was 145℃.

[0080] The thickness of the warm mix asphalt film adhered to the mixture was 6 μm.

[0081] Example 2 (SMA-5 surface layer high stability steel slag asphalt mixture)

[0082] The high stability steel slag asphalt mixture comprises the following raw materials by weight: 70 parts of coarse aggregate blast furnace steel slag with a particle size greater than 2.36 mm, 50 parts of fine aggregate andesite with a particle size less than 2.36 mm, 10 parts of titanate coupling agent GR-201 modified limestone mineral powder, 22 parts of No. 90 base asphalt, 18 parts of steel slag stabilizer, and 0.44 parts of warm mix asphalt agent LEADCAP.

[0083] The indexes of the blast furnace steel slag are shown in Table 5:

[0084] Table 5

[0085] Test Index Steel Slag Aggregate Crushing Value (%) 15 Soundness (%) 7 Needle and Flake Content (> 9.5 mm, %) 5 Weak Particle Content (%) 2.5 Wear Value (%) 11 Adhesion to Asphalt (Grade) 6

[0086] The andesite has an apparent relative density of 2.812, a sand equivalent of 78%, and a methylene blue value of 1.8 g / kg.

[0087] The SMA-5 surface layer high stability steel slag asphalt mixture has the following proportions of each grade of aggregate in the aggregate grading:

[0088] Mineral powder: 0-3 mm andesite: 3-5 mm blast furnace steel slag = 8:31:61; the amount of lignin fiber is 3.5 wt‰; the amount of asphalt is 6.1 wt%.

[0089] The 3-5 mm blast furnace steel slag has an apparent relative density of 3.370, a bulk volume relative density of 3.168, a water absorption rate of 2.2%, and a free calcium oxide content of 1.3%.

[0090] The synthesis gradation of the SMA-5 high stability steel slag asphalt mixture is shown in Table 6.

[0091] Table 6

[0092] Screen Opening Size (mm) 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Passing Rate (%) 72 47.1 33.4 23.4 15.2 8.7 7.3 5.2 Required Range (%) 68-85 38-68 24-50 15-38 10-28 7-20 5-15 4-8

[0093] The preparation method of the high stability steel slag asphalt mixture comprises the following steps:

[0094] (1) Preparation of warm mix asphalt: warm mix asphalt agent LEADCAP is added into No. 90 base asphalt, and stirring is carried out at a temperature of 140℃ and a rotating speed of 1000 revolutions / min for 10 min;

[0095] (2) Stability modification of coarse aggregate steel slag: the coarse aggregate blast furnace steel slag is mixed with the steel slag stabilizer for 80 s at a mixing temperature of 145℃;

[0096] (3) Mixture mixing: the stability modified coarse aggregate steel slag and the lignin fiber are mixed with the fine aggregate andesite for 100 s, then the warm mix asphalt obtained in step (1) is added for mixing for 100 s, and after the end, the modified mineral powder is added for mixing for 90 s; wherein the mixing temperature is 150℃.

[0097] The thickness of the warm mix asphalt film adhered to the mixture is 8μm.

[0098] Example 3 (AC-13 high stability steel slag asphalt mixture)

[0099] The high stability steel slag asphalt mixture comprises the following raw materials by weight: coarse aggregate blast furnace steel slag with a particle size greater than 2.36mm 60 parts, fine aggregate basalt with a particle size less than 2.36mm 40 parts, titanium ester coupling agent GR-201 modified limestone mineral powder 12 parts, No. 90 base asphalt 20 parts, steel slag stabilizer 16 parts, and warm mix asphalt agent LEADCAP 0.4 parts.

[0100] The indexes of the blast furnace steel slag are shown in Table 7:

[0101] Table 7

[0102] Test Index Steel Slag Aggregate Crushing Value (%) 12 Soundness (%) 8 Needle and Flake Content (> 9.5 mm, %) 2 Weak Particle Content (%) 2.0 Wear Value (%) 10 Adhesion to Asphalt (Grade) 7

[0103] The basalt has an apparent relative density of 2.736, a sand equivalent of 76%, and a methylene blue value of 2.5g / kg.

[0104] The aggregate gradation of the AC-13 high stability steel slag asphalt mixture is as follows: 10-15mm blast furnace steel slag: 5-10mm blast furnace steel slag: 3-5mm blast furnace steel slag: 0-3mm basalt: mineral powder = 58:12:18:9:3; and the asphalt dosage is 4.6wt%.

[0105] The apparent relative density of the 3-5 mm blast furnace steel slag is 3.378, the bulk volume relative density is 3.172, the water absorption is 2.3%, and the free calcium oxide content is 1.4%.

[0106] The apparent relative density of the 5-10 mm blast furnace steel slag is 3.340, the bulk volume relative density is 3.100, the water absorption is 1.9%, and the free calcium oxide content is 1.61%.

[0107] The apparent relative density of the 10-15 mm blast furnace steel slag is 3.303, the bulk volume relative density is 3.132, the water absorption is 1.8%, and the free calcium oxide content is 2.2%.

[0108] The synthetic gradation of the AC-13 high-stability steel slag asphalt mixture is shown in Table 8:

[0109] Table 8

[0110] Screen Opening Size (mm) 16 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Passing Rate (%) 100 98 79.5 47.5 32.3 21.6 14.7 9.5 7.6 6.7 Graded Median (%) 100 95 76.5 53 37 26.5 19 13.5 10 6

[0111] The preparation method of the high-stability steel slag asphalt mixture comprises the following steps:

[0112] (1) Preparation of warm mix asphalt: warm mix asphalt LEADCAP is added to No. 90 base asphalt, and stirring is carried out at a temperature of 130 DEG C and a rotating speed of 1200 r / min for 12 min;

[0113] (2) Stability modification of coarse aggregate steel slag: 5-10 mm blast furnace steel slag in the coarse aggregate steel slag is mixed with a steel slag stabilizer for 30 s, and then 3-5 mm blast furnace steel slag and 10-15 mm blast furnace steel slag are added and mixed for 60 s; wherein the mixing temperature is 140 DEG C;

[0114] (3) Mixture mixing: the stability modified coarse aggregate steel slag is mixed with fine aggregate basalt for 110 s, and then the warm mix asphalt obtained in step (1) is added and mixed for 100 s, and then modified mineral powder is added and mixed for 85 s after the end; wherein the mixing temperature is 150 DEG C.

[0115] In the present application, the thickness of the warm mix asphalt film in the high-stability steel slag asphalt mixture preparation method is 7 μm.

[0116] Comparative Example 1

[0117] The high-stability steel slag asphalt mixture comprises the following raw materials in parts by weight: coarse aggregate blast furnace steel slag with a particle size greater than 2.36 mm 80 parts, fine aggregate granite with a particle size less than 2.36 mm 20 parts, titanate coupling agent GR-201 modified limestone powder 8 parts, No. 90 base asphalt 22 parts, steel slag stabilizer 12 parts, and asphalt warm-mixing agent LEADCAP 0.3 part.

[0118] The other is the same as in Example 3.

[0119] Comparative Example 2

[0120] The high-stability steel slag asphalt mixture comprises the following raw materials in parts by weight: coarse aggregate blast furnace steel slag with a particle size greater than 2.36 mm 85 parts, fine aggregate andesite with a particle size less than 2.36 mm 15 parts, titanate coupling agent GR-201 modified limestone powder 10 parts, No. 90 base asphalt 24 parts, steel slag stabilizer 15 parts, and asphalt warm-mixing agent LEADCAP 0.4 part.

[0121] The other is the same as in Example 3.

[0122] Comparative Example 3

[0123] Different from Example 2, the coarse aggregate steel slag is converter steel slag, wherein the apparent relative density of the converter steel slag is 2.95, the bulk volume relative density is 2.912, the water absorption is 2.43%, the crushing value is 17.2%, the soundness is 12%, the needle and flake content ≥ 9.5 mm is 12%, the weak particle content is 5%, and the abrasion value is 18.5%.

[0124] The other is the same as in Example 2.

[0125] Comparative Example 4

[0126] Different from Example 2, the coarse aggregate steel slag is open-hearth steel slag, wherein the apparent relative density of the open-hearth steel slag is 3.124 g / cm3, the bulk volume relative density is 3.100, the water absorption is 2.14%, the crushing value is 25.3%, the soundness is 11%, the needle and flake content ≥ 9.5 mm is 10%, the weak particle content is 7%, and the abrasion value is 23%.

[0127] The other is the same as in Example 2.

[0128] Comparative Example 5

[0129] Different from Example 2, the fine aggregate is limestone, wherein the apparent relative density of the limestone is 2.610, the bulk volume relative density is 2.574, the water absorption is 0.54%, the methylene blue value is 2.1%, and the sand equivalent is 80%.

[0130] Comparative Example 6

[0131] The difference from Example 1 is that the asphalt used is SBS (1-D type), the hot mixing temperature is 185°C, and the indices of the asphalt are shown in Table 9. The others are the same as in Example 1.

[0132] Table 9 Performance indices of SBS modified asphalt

[0133]

[0134]

[0135] Comparative Example 7

[0136] The difference from Example 2 is that the preparation method of the high-stability steel slag asphalt mixture of the comparative example comprises the following steps:

[0137] (1) Preparation of warm mix asphalt: warm mix asphalt agent LEADCAP is added to No. 90 base asphalt, and stirring is carried out at a temperature of 140°C and a rotation speed of 1000 rpm for 10 min;

[0138] (2) Direct mixing: first, the coarse aggregate steel slag and the steel slag stabilizer are added, and then the fine aggregate andesite, modified mineral powder and the warm mix asphalt obtained in step (1) are added in sequence; mixing is carried out at 150°C to obtain the steel slag asphalt mixture.

[0139] The thickness of the warm mix asphalt film adhered to the mixture is 8 μm.

[0140] The performance of the steel slag asphalt mixture of each example and comparative example is determined as follows, and the determination results are shown in Table 10. The free calcium oxide content in Table 10 is the free calcium oxide content on the surface of the steel slag after mixing of the coarse aggregate steel slag and the steel slag stabilizer.

[0141] Table 10

[0142]

[0143]

Claims

1. A method for preparing a high-stability steel slag asphalt mixture, characterized by, It comprises the following steps: (1) Preparation of warm mix asphalt: incorporate asphalt modifier in No. 90 base asphalt, stir at a temperature of 130-150℃ and a rotation speed of 1000-1200 r / min for 10-12 min; (2) Stabilization and modification of coarse aggregate steel slag: mix steel slag coarse aggregate with steel slag stabilizer for 80-90 s at a temperature of 140-150℃; The steel slag stabilizer is prepared by the following method:

1. Blending: mix FeO powder with a purity of 99.5% and an average particle size of 180-200 µm with MgO powder with a purity of 99.9% and an average particle size of 0.2-0.25 µm by grinding to obtain a powder mixture; wherein the mass ratio of FeO powder to MgO powder is 21-22:78-79; 2. Pelletizing: use a press to compress the powder mixture obtained in step (1) into pellets with a diameter of 7-9 mm and a weight of 0.3-0.5 g; 3. First sintering: sinter the pellets obtained in step (2) in a gas-tight electric furnace at a high-purity argon gas pressure of 6-10 atm and a temperature of 1770-1780 K for 24 hours; 4. Cooling, grinding, and re-pelletizing: cool the pellets obtained after the first sintering in step (3) in the furnace at a rate of 300 K / h, then take out the pellets, crush them into powder, grind, and re-pelletize; 5. Second sintering: re-pelletize the pellets obtained in step (4) under the same conditions as the first sintering in step (3) to obtain the steel slag stabilizer; (3) Mixing: first mix the stabilized and modified coarse aggregate steel slag with fine aggregate stone for 90-120 s, then add the warm mix asphalt obtained in step (1) and mix for 90-100 s, and finally add modified mineral powder and mix for 80-90 s; the mixing temperature is 145-150℃ in all cases; The aggregate gradation range in the high-stability steel slag asphalt mixture is one of the following a, b, and c: a. In the AC-13 aggregate gradation, the proportion of each size is: 10-15 mm steel slag: 5-10 mm steel slag: 3-5 mm steel slag: 0-3 mm stone: modified mineral powder = 56-60:10-14:16-18:9:3; the amount of No. 90 base asphalt is 4.6-4.8 wt%; b. In the SMA-13 aggregate gradation, the proportion of each size is: Modified mineral powder: 0-3 mm stone: 5-10 mm steel slag: 10-15 mm steel slag = 8-10:10-14:30-35:44-48; the amount of No. 90 base asphalt is 5.9-6.1 wt%; it also includes lignin fibers, the amount of which is 3.3-3.5 wt‰; c. In the SMA-5 aggregate gradation, the proportion of each size is: Modified mineral powder: 0-3 mm stone: 3-5 mm steel slag = 8:31:59-63; the amount of No. 90 base asphalt is 6.1-6.3 wt%; it also includes lignin fibers, the amount of which is 3.5-3.7 wt‰.

2. The method of claim 1, wherein the high-stability steel slag asphalt mixture is prepared by mixing the steel slag, the filler, and the asphalt at a ratio of 50-70: 10-30: 20-30. The crushing value of the coarse aggregate steel slag is less than or equal to 20%, the firmness is less than or equal to 10%, the content of needle and flake with a size of more than 9.5 mm is less than or equal to 6%, the content of weak particles is less than or equal to 3.5%, the abrasion value is less than or equal to 20%, and the adhesion to asphalt is more than or equal to 6 levels. The coarse aggregate steel slag is a blast furnace steel slag; and the fine aggregate stone is at least one of andesite, granite or basalt.

3. The method of claim 1, wherein the high-stability steel slag asphalt mixture is prepared by mixing 100 parts by weight of the steel slag, 100 parts by weight of the filler, 100 parts by weight of the asphalt, and 0.1 to 0.3 parts by weight of the additive. The modified mineral powder is a limestone mineral powder modified by a titanate coupling agent GR-201; the particle size of the steel slag stabilizer is 0.075-0.3 mm; and the asphalt modifier is a warm mixing agent LEADCAP.

4. The method of claim 1, wherein the high-stability steel slag asphalt mixture is prepared by mixing 100 parts by weight of the asphalt, 50 to 150 parts by weight of the steel slag, 20 to 60 parts by weight of the filler, and 2 to 6 parts by weight of the polymer. The normal temperature bleeding loss of the steel slag asphalt mixture is less than 0.1%; the loss of the 60 DEG C flying test is 6-7%; the dynamic stability test under the condition of 70 DEG C and 1.0 MPa is 4000-5000 times; the deformation of the 50 DEG C Hamburg rutting test for 20000 times is 3-4 mm; the freeze-thaw splitting strength ratio is 88-95%; and the low-temperature bending strain is 2900-3400 με.

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