Asphalt mixture containing waste nickel slag powder

Abstract

The invention discloses an asphalt mixture containing waste nickel slag powder. The asphalt mixture is prepared from the following components in parts by mass: 90 to 100 parts of aggregate, 4.0 to 4.5 parts of asphalt and 4.5 to 5.5 parts of filler, wherein the filler is limestone mineral powder doped with nickel slag powder; the nickel slag powder is prepared by adopting the following method: firstly, crushing a water-cooled nickel slag block, then carrying out multi-stage ball milling, and finally, screening and drying the nickel slag powder subjected to ball milling treatment to obtain the nickel slag powder. The asphalt mixture disclosed by the invention has good water damage resistance, high-temperature stability and ultraviolet aging resistance, and meanwhile, the preparation cost of the asphalt mixture can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to an asphalt mixture containing waste nickel slag powder. Background Art

[0002] Asphalt mixtures mainly consist of three major elements: asphalt, aggregates, and fillers, among which fillers play an indispensable role. In the prior art, the filler of asphalt mixtures is mineral powder, which can enhance the strength, stability, and extend the service life of asphalt mixtures. However, the series of processes from the mining, processing to the application of mineral powder are often accompanied by over-exploitation of natural resources, damage to the ecological environment, and unnecessary energy consumption. These problems undoubtedly become the key bottlenecks restricting the development of sustainable road construction. Moreover, asphalt mixtures based on mineral powder also have problems such as high low-temperature brittleness and insufficient asphalt film thickness, which are prone to cause pavement spalling, cracking, and weak water damage resistance. Therefore, asphalt mixtures based on mineral powder have problems of high energy consumption and heavy pollution in mineral powder production and insufficient durability of asphalt mixtures. Nickel slag, as a solid waste generated during the smelting of nickel ferroalloy, its recycling value is gradually attracting wide attention in the industry. Summary of the Invention

[0003] Object of the Invention: The object of the present invention is to provide an asphalt mixture containing waste nickel slag powder, which has good water damage resistance, high-temperature stability, and anti-ultraviolet aging performance, and can also significantly reduce the cost of preparing asphalt mixtures.

[0004] Technical Solution: The asphalt mixture containing waste nickel slag powder according to the present invention comprises the following components in parts by mass: 90 - 100 parts of aggregates, 4.0 - 4.5 parts of asphalt, and 4.5 - 5.5 parts of fillers; wherein, the filler is limestone mineral powder admixed with nickel slag powder.

[0005] Among them, the filler consists of the following components in mass percentage: 0 - 50% of mineral powder and 50 - 100% of nickel slag powder.

[0006] Among them, the nickel slag powder is prepared by the following method: first, crush the water-cooled nickel slag blocks, perform multi-stage ball milling after crushing, and finally screen and dry the nickel slag powder after ball milling treatment to obtain nickel slag powder.

[0007] First, use a planetary ball mill to preliminarily grind the nickel slag, and then perform secondary high-energy ball milling on the nickel slag powder obtained by the planetary ball mill. Preliminary grinding (planetary ball mill): Refine the nickel slag blocks after jaw crushing into coarse powder (about 50 - 200 μm), initially break the particle agglomeration, and improve the uniformity of subsequent processing; ball milling time: 2 - 4 hours, specifically depending on the hardness of the nickel slag and the target particle size; ball-to-material ratio: 10:1 - 15:1 (mass ratio of balls to materials) to ensure sufficient collision and grinding. Secondary high-energy ball milling treatment: Further reduce the particle size of the nickel slag powder to 5 - 150 μm, and at the same time activate the active components such as SiO2 and Fe2O3 in the nickel slag through mechanochemical action, enhancing its chemical bonding ability with asphalt. Ball milling time: 6 - 12 hours to improve the particle fineness and activity. Ball-to-material ratio: Increase to 20:1 - 25:1, and control the specific surface area of the particles at 300 - 450m 2 / kg through secondary ball milling, thereby balancing asphalt adsorption and asphalt film thickness (maintaining 8 - 10 μm) and avoiding thin asphalt film caused by excessive adsorption.

[0008] When the nickel slag powder obtained by the above method is doped into the asphalt mixture, it can improve the high-temperature stability, water damage resistance, and low-temperature crack resistance of the asphalt mixture. The reasons are as follows: The micron-sized particles of the nickel slag powder can fill the gaps in the aggregate skeleton, improving the compactness of the mixture. That is, the particle size distribution of 5 - 150 μm can fill the voids of both coarse and fine aggregates simultaneously, reducing the asphalt demand while increasing the structural compactness (reducing the porosity of the asphalt mixture by 15 - 20%), thereby reducing high-temperature rutting deformation and having good high-temperature stability performance. At the same time, the active oxides (such as SiO2) in the nickel slag powder can chemically adsorb with asphalt. High-energy ball milling causes lattice defects and free metal ions to form on the surface of the nickel slag (forming an amorphous structure on the surface of the nickel slag, increasing the free Fe 2+ 、Si 4 + ion concentration and enhancing the chemical bonding ability with asphalt), promoting chemical bonding with the polar components in asphalt (such as the complexation of Fe 2+ with asphaltene), thereby enhancing the interfacial adhesion between the aggregate and the asphalt slurry, and reducing the spalling risk caused by water erosion. At the same time, the rigid particles of the nickel slag powder can disperse stress concentration, and the active components improve the toughness of asphalt, delaying the problem of low-temperature cracking.

[0009] Among them, the particle size of the nickel slag powder is 5 - 150 μm; the particle size of the nickel slag powder is basically the same as that of the mineral powder.

[0010] Among them, the screen aperture of the screening process is 0.075 mm; the drying temperature is 175 °C, and the drying time is 0.5 - 1 h.

[0011] Among them, the aggregate is at least one of basalt or limestone.

[0012] Among them, the asphalt is at least one of SBS modified asphalt and 70# base asphalt.

[0013] The preparation method of the above asphalt mixture containing waste nickel slag powder includes the following steps:

[0014] (1) Mix the filler at room temperature using a drum mixer for 5 - 10 minutes to obtain a uniformly dispersed filler.

[0015] (2) Heat the aggregate and the filler at 160°C - 180°C for 4 hours respectively. Meanwhile, heat the asphalt at 135°C for 1 - 2 hours.

[0016] (3) At 160 - 180°C, dry - mix the aggregate for 90 seconds.

[0017] (4) Add the asphalt to the aggregate in step (3) and mix for 90 seconds until uniform to obtain a mixture.

[0018] (5) Add the pre - heated filler to the mixture and stir for 90 seconds until uniform. Cast and cure the mixed mixture at 140°C - 160°C to obtain an asphalt mixture with nickel slag powder replacing mineral powder.

[0019] Nickel slag is mainly composed of minerals such as fayalite and ferro - olivine, and its chemical composition is complex, with relatively high contents of SiO2 and Fe2O3. Replacing mineral powder with nickel slag can utilize its active components (such as SiO2, Fe2O3) to enhance the asphalt adhesion, optimize the particle gradation to improve the density, and maintain the effective asphalt film thickness by reducing the specific surface area, thereby improving the crack resistance, waterproof property, high - temperature stability and anti - ultraviolet aging performance of the asphalt mixture; at the same time, nickel slag is used as industrial solid waste for resource utilization, which has the functions of reducing costs and environmental benefits.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The addition of the nickel slag powder prepared by the present invention can significantly improve the freeze-thaw splitting strength ratio of the asphalt mixture, thereby effectively improving the water damage resistance of the asphalt pavement; (2) After the nickel slag powder prepared by the present invention is added, the dynamic stability, Marshall stability and maximum bending strain of the asphalt mixture can be guaranteed to be not less than 100% of the asphalt mixture prepared with limestone ore powder as filler, indicating that the nickel slag of the present invention can effectively ensure the high and low temperature performance of the asphalt mixture; (3) Compared with the asphalt mixture prepared with 100% limestone ore powder as filler, the asphalt mixture of the present invention has good water damage resistance and UV aging resistance, and nickel slag powder as a substitute for limestone ore powder can effectively reduce the mining of natural fillers and absorb solid waste nickel slag, which not only has significant environmental benefits but also can reduce the preparation cost of asphalt mixture; (4) Compared with limestone ore powder, the nickel slag powder prepared by the present invention has a relatively rough surface, which will help increase friction and increase asphalt viscosity, thereby improving the overall strength and density of the asphalt mixture and ensuring the structural stability of the asphalt pavement under high and low temperature conditions. DETAILED DESCRIPTION

[0021] In the present invention, the water-cooled nickel slag blocks are sourced from Jiangsu Delong Nickel Industry Co., Ltd. and are obtained by high-pressure water quenching and rapid cooling of the molten slag during nickel smelting.

[0022] The nickel slag powder is prepared by the following method: specifically, a water-cooled nickel slag block is crushed by a jaw crusher, and the nickel slag is preliminarily ground by a planetary ball mill, wherein the ball milling time is 4 hours and the ball-to-material ratio is 15:1; the nickel slag powder obtained by grinding by the planetary ball mill is subjected to a secondary high-energy ball milling treatment, wherein the ball milling time is 12 hours and the ball-to-material ratio is 25:1; and finally, the nickel slag powder subjected to the high-energy ball milling treatment is sieved through a sieve with an aperture of 0.075 mm, and the sieved material is dried in an oven at 175° C. for 0.5 to 1 hour to obtain nickel slag powder with a particle size of 5 to 150 μm.

[0023] The asphalt mixtures of Examples 1 to 6 were prepared based on the nickel slag powder prepared by the above method.

[0024] Example 1

[0025] The method for preparing an asphalt mixture containing waste nickel slag powder of the present invention comprises the following steps:

[0026] (1) nickel slag powder and limestone ore powder were mixed in a mass ratio of 9:1 and mixed with a drum mixer at room temperature for 5 minutes to obtain a filler mixture containing 90 wt% of nickel slag powder;

[0027] (2) Weigh 90 parts by mass of basalt aggregate and 4.5 parts by mass of filler mixture, put them on a tray together, and heat them in an oven at 165 °C for 4 hours; put the asphalt in an oven at 135 °C and heat it for 1 hour; after the heating is completed, set the temperature of the asphalt mixture mixing pot to 165 °C;

[0028] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0029] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0030] (5) Add the preheated filler mixture to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140 °C - 160 °C to obtain the asphalt mixture.

[0031] Example 2

[0032] The preparation method of the asphalt mixture containing waste nickel slag powder of the present invention includes the following steps:

[0033] (1) Blend according to the mass ratio of nickel slag powder to limestone powder of 8:2, and mix with a drum mixer at room temperature for 8 min to obtain a filler mixture with uniformly dispersed nickel slag powder of 80 wt%;

[0034] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of filler mixture, put them on a tray together, and heat them in an oven at 165 °C for 4 hours; put the asphalt in an oven at 135 °C and heat it for 1 hour; after the heating is completed, set the temperature of the asphalt mixture mixing pot to 165 °C;

[0035] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0036] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0037] (5) Add the preheated filler mixture to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140 °C - 160 °C to obtain the asphalt mixture.

[0038] Example 3

[0039] The preparation method of the asphalt mixture containing waste nickel slag powder of the present invention includes the following steps:

[0040] (1) Mix according to the mass ratio of nickel slag powder to limestone powder of 7:3, and mix with a drum mixer at room temperature for 8 minutes to obtain a filler mixture with evenly dispersed nickel slag powder of 70 wt%;

[0041] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of the filler mixture, and place them on trays and put them into an oven at 165 °C for 4 hours; put the asphalt into an oven at 135 °C for 1 hour; after heating is completed, set the temperature of the asphalt mixture mixing pot to 165 °C;

[0042] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0043] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0044] (5) Add the preheated filler mixture to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140 °C - 160 °C to obtain the asphalt mixture.

[0045] Example 4

[0046] The preparation method of the asphalt mixture containing waste nickel slag powder of the present invention includes the following steps:

[0047] (1) Mix according to the mass ratio of nickel slag powder to limestone powder of 6:4, and mix with a drum mixer at room temperature for 8 minutes to obtain a filler mixture with evenly dispersed nickel slag powder of 60 wt%;

[0048] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of the filler mixture, and place them on trays and put them into an oven at 165 °C for 4 hours; put the asphalt into an oven at 135 °C for 1 hour; after heating is completed, set the temperature of the asphalt mixture mixing pot to 165 °C;

[0049] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0050] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0051] (5) Add the preheated filler mixture to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140 °C - 160 °C to obtain the asphalt mixture.

[0052] Example 5

[0053] Preparation method of asphalt mixture containing waste nickel slag powder, comprising the following steps:

[0054] (1) Mix in accordance with a mass ratio of nickel slag powder to limestone powder of 5:5, and mix with a drum mixer at normal temperature for 8 min to obtain a filler mixture with evenly dispersed nickel slag powder accounting for 50 wt%;

[0055] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of the filler mixture, place them on trays together, and heat in an oven at 165 °C for 4 hours; place the asphalt in an oven at 135 °C and heat for 1 hour; after heating is completed, set the temperature of the asphalt mixture mixing pot to 165 °C;

[0056] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0057] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0058] (5) Add the preheated filler mixture to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140 °C to 160 °C to obtain the asphalt mixture.

[0059] Example 6

[0060] Preparation method of asphalt mixture containing waste nickel slag powder, comprising the following steps:

[0061] (1) The filler consists of 100% nickel slag powder;

[0062] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of nickel slag powder, place them on trays together, and heat in an oven at 165 °C for 4 hours; place the asphalt in an oven at 135 °C and heat for 1 hour; after heating is completed, set the temperature of the asphalt mixture mixing pot to 165 °C;

[0063] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0064] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0065] (5) Add the preheated nickel slag powder to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140 °C to 160 °C to obtain the asphalt mixture.

[0066] Comparative Example 1

[0067] A preparation method of asphalt mixture, comprising the following steps:

[0068] (1) The filler consists of 100% limestone powder;

[0069] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of limestone powder, put them on a tray together and heat them in an oven at 165°C for 4 hours; put the asphalt in an oven at 135°C and heat it for 1 hour; after the heating is completed, set the temperature of the asphalt mixture mixing pot to 165°C;

[0070] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0071] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0072] (5) Add the preheated limestone powder to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140°C - 160°C to obtain the asphalt mixture.

[0073] Comparative Example 2

[0074] A preparation method of nickel slag powder: Specifically, use a jaw crusher to crush the water-cooled nickel slag blocks, and then use a planetary ball mill to preliminarily grind the nickel slag. The ball milling time is 4 hours and the ball-to-material ratio is 15:1; perform secondary high-energy ball milling treatment on the nickel slag powder ground by the planetary ball mill. The ball milling time is 16 hours and the ball-to-material ratio is 30:1; finally, screen the nickel slag powder treated by high-energy ball milling under a sieve with a pore size of 0.075 mm, and dry the undersize material in an oven at 175°C for 0.5 - 1 h to obtain nickel slag powder with a particle size of 5 - 50 μm. The specific surface area of the nickel slag powder increases from 300 m 2 / kg to 500 m 2 / kg.

[0075] Based on the above nickel slag powder to prepare asphalt mixture, comprising the following steps:

[0076] (1) Mix according to the mass ratio of nickel slag powder to limestone powder of 7:3, and mix with a drum mixer at room temperature for 8 min to obtain a filler mixture with evenly dispersed nickel slag powder of 70 wt%;

[0077] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of the filler mixture, put them on a tray together and heat them in an oven at 165°C for 4 hours; put the asphalt in an oven at 135°C and heat it for 1 hour; after the heating is completed, set the temperature of the asphalt mixture mixing pot to 165°C;

[0078] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixer and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0079] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixer and mix for 90 s until uniform to obtain a mixture;

[0080] (5) Add the preheated filler mixture to the mixture and use the mixer to stir for 90 s until uniform; Pour and cure the asphalt mixture in the mixer at 140 °C - 160 °C to obtain the asphalt mixture.

[0081] Comparative Example 3

[0082] A preparation method of nickel slag powder: Specifically: Use a jaw crusher to crush the water-cooled nickel slag blocks, and then use a planetary ball mill to preliminarily grind the nickel slag. The ball milling time is 4 hours and the ball-to-material ratio is 15:1; Perform secondary high-energy ball milling treatment on the nickel slag powder obtained by planetary ball milling. The ball milling time is 12 hours and the ball-to-material ratio is 25:1; Finally, screen the nickel slag powder treated by high-energy ball milling under a sieve with a pore size of 0.075 mm, and dry the undersize material in an oven at 195 °C for 0.5 - 1 h to obtain nickel slag powder with a particle size of 5 - 150 μm.

[0083] Based on the above nickel slag powder to prepare asphalt mixture, including the following steps:

[0084] (1) Mix according to the mass ratio of nickel slag powder to limestone powder of 7:3, and mix with a drum mixer at room temperature for 8 min to obtain a filler mixture with uniformly dispersed nickel slag powder of 70 wt%;

[0085] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of filler mixture, put them on trays and place them in an oven at 165 °C for 4 hours; Put the asphalt in an oven at 135 °C for 1 hour; After the heating is completed, set the temperature of the asphalt mixture mixer to 165 °C;

[0086] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixer and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0087] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixer and mix for 90 s until uniform to obtain a mixture;

[0088] (5) Add the preheated filler mixture to the mixture and use the mixer to stir for 90 s until uniform; Pour and cure the asphalt mixture in the mixer at 140 °C - 160 °C to obtain the asphalt mixture.

[0089] Comparative Example 4

[0090] A preparation method of nickel slag powder: Specifically, a jaw crusher is used to crush the water-cooled nickel slag blocks, and then a planetary ball mill is used to preliminarily grind the nickel slag. The ball milling time is 4 hours, and the ball-to-material ratio is 15:1. The nickel slag powder obtained by grinding with the planetary ball mill is subjected to secondary high-energy ball milling treatment. The ball milling time is 12 hours, and the ball-to-material ratio is 25:1. Finally, the nickel slag powder treated by high-energy ball milling is screened under a sieve with a pore size of 0.075 mm, and the undersize after screening is dried in an oven at 175 °C for 0.2 h to obtain nickel slag powder with a particle size of 5 - 150 μm.

[0091] Based on the above nickel slag powder, an asphalt mixture is prepared, including the following steps:

[0092] (1) Mix according to the mass ratio of nickel slag powder to limestone powder of 7:3, and mix with a drum mixer at room temperature for 8 min to obtain a filler mixture with 70 wt% of evenly dispersed nickel slag powder;

[0093] (2) Weigh 90 parts by mass of basalt aggregate and 5.5 parts by mass of the filler mixture, and put them on trays into an oven at 165 °C and heat for 4 hours; put the asphalt into an oven at 135 °C and heat for 1 hour; after the heating is completed, set the temperature of the asphalt mixture mixing pot to 165 °C;

[0094] (3) Place the coarse aggregate and fine aggregate in the asphalt mixture mixing pot and dry mix for 90 s to pre-mix the coarse and fine aggregates;

[0095] (4) Add 4.5 parts by mass of asphalt (SBS modified asphalt) to the mixing pot and mix for 90 s until uniform to obtain a mixture;

[0096] (5) Add the preheated filler mixture to the mixture, and use the mixing pot to stir for 90 s until uniform; pour and cure the asphalt mixture in the mixing pot at 140 °C - 160 °C to obtain the asphalt mixture.

[0097] Evaluate the high-temperature performance, water stability, stiffness, and anti-ultraviolet aging performance of the asphalt mixtures prepared in Examples 1 - 6 and Comparative Examples 1 - 4. Among them, the dynamic modulus is tested at a frequency of 0.1 Hz. The test results are shown in Table 1.

[0098] Table 1

[0099]

[0100] As can be seen from Table 1, the asphalt mixture of Example 3 has good high-temperature stability, water damage resistance and anti-ultraviolet aging performance; when the nickel slag content is 70 wt.%, the mass loss rate is the lowest (0.68%), which is better than that of Comparative Example 1 (1.52%). This is because components such as Fe2O3 and SiO2 in nickel slag form an amorphous structure through high-energy ball milling, which can absorb ultraviolet rays and convert them into heat energy, slowing down the photo-oxidation reaction of asphalt. At the same time, the dense structure formed by the filling of nickel slag powder (the porosity is reduced by at least 15%) can effectively reduce oxygen penetration and inhibit the free radical chain reaction; so that the asphalt does not age during the long-term use process, thereby maintaining the stability of the asphalt mixture structure.

[0101] From the comparison between Examples 1 and 2, it can be seen that when the mixing time is increased from 5 min to 8 min, the interfacial bonding between nickel slag and mineral powder can be made closer, the asphalt mortar can be more fully wrapped, the plasticity of the mixture is improved, and the flow value of Example 2 (25.01 mm) is better than that of Example 1 (24.85 mm). From the comparison between Example 3 and Example 6, it can be seen that since the surface roughness of nickel slag powder is higher than that of mineral powder, when the dosage of nickel slag powder is too high, the grading curve of the asphalt mixture deviates from the ideal S-shaped curve, and the porosity increases; at the same time, too high a dosage of nickel slag powder will cause a significant increase in the active components in the system, resulting in excessive adsorption of asphalt, and then leading to a decrease in the effective asphalt film thickness (<6 μm), resulting in a decrease in the high and low temperature performance of the asphalt mixture (the rut depth of Example 6 is 5.95 mm) (too thin an asphalt film will destroy the balance between structural asphalt and free asphalt in the asphalt mixture, resulting in a sudden drop in low temperature crack resistance (enhanced brittleness) and a sharp increase in the risk of water damage (water is easily infiltrated into the uncoated aggregates), and at the same time, the high temperature rutting resistance will be weakened due to insufficient lubrication between particles). The dynamic modulus is the highest (593 MPa) when the dosage of nickel slag powder is 70 wt.%, because the rigid particles of nickel slag form a "skeleton-mastic" interlocking structure with asphalt; when excessive amounts are incorporated (Example 6), it will lead to too high a proportion of rigid particles, increasing the brittleness of the asphalt mixture, and thus the modulus decreases (the dynamic modulus of Example 6 is 478 MPa). From the comparison between Example 3 and Comparative Examples 3 to 4, it can be seen that when the drying temperature > 180 °C, the hydroxyl groups (-OH) on the surface of nickel slag dehydrate, the active sites decrease, and the loss of hydroxyl groups weakens the chemical bonding between nickel slag and asphalt, resulting in a decrease in interfacial adhesion, and water is more likely to infiltrate and cause peeling; secondly, the destruction of the rigid skeleton-mastic interlocking structure leads to a decrease in high temperature shear resistance; at the same time, the loss of hydroxyl groups as ultraviolet absorption sites accelerates the photooxidation of asphalt; in addition, high temperature thermal stress induces microcracks in nickel slag, and the increase in porosity will reduce the dynamic modulus. These effects together lead to a comprehensive decline in the water stability, high temperature stability and durability of the mixture. When the drying time is insufficient (<0.5 h), the residual water causes the filler to agglomerate. On the one hand, the distribution of nickel slag in the mixture is uneven, and on the other hand, the residual water evaporates during mixing to form micropores, reducing the density, thus reducing the Marshall stability. From the comparison between Example 3 and Comparative Example 2, it can be seen that when the grinding is excessive, the particle size will be refined to 5 - 50 μm, and the specific surface area increases from 300 m 2 / kg to 500 m 2 / kg, and the activity is over-activated, resulting in an increase in the asphalt adsorption amount. Excessive adsorption will lead to a decrease in the effective asphalt film thickness, bringing problems similar to those caused by excessive addition of nickel slag powder.

Claims

1. An asphalt mixture containing waste nickel slag powder, characterized in that, It comprises components in the following parts by mass: 90 - 100 parts of aggregate, 4.0 - 4.5 parts of asphalt, and 4.5 - 5.5 parts of filler; wherein, the filler is limestone powder admixed with nickel slag powder; the nickel slag powder is prepared by the following method: first, crush the water-cooled nickel slag blocks, then conduct multi-stage ball milling, and finally screen and dry the nickel slag powder after ball milling to obtain the nickel slag powder.

2. The asphalt mixture containing waste nickel slag powder according to claim 1, characterized in that: The filler is composed of components in the following mass percentages: 0 - 50% of powder and 50 - 100% of nickel slag powder.

3. The asphalt mixture containing waste nickel slag powder according to claim 1, wherein: The particle size of the obtained nickel slag powder is 5 - 150 μm.

4. The asphalt mixture containing waste nickel slag powder according to claim 1, wherein: The ball milling time of the first-stage ball milling is 2 - 4 hours, and the ball-to-material ratio is 10:1 - 15:

1.

5. The asphalt mixture containing waste nickel slag powder according to claim 1, characterized in that: The ball milling time of the second-stage ball milling is 6 - 12 hours, and the ball-to-material ratio is 20:1 - 25:

1.

6. The asphalt mixture containing waste nickel slag powder according to claim 1, wherein: The screen aperture of the screening process is 0.075 - 0.080 mm.

7. The asphalt mixture containing waste nickel slag powder according to claim 1, wherein: The drying temperature is 175 - 180 °C, and the drying time is 0.5 - 1 h.

8. The asphalt mixture containing waste nickel slag powder according to claim 1, characterized in that: The aggregate is at least one of basalt and limestone.

9. The asphalt mixture containing waste nickel slag powder according to claim 1, characterized in that: The asphalt is at least one of SBS modified asphalt and 70# base asphalt.

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