Metallurgical solid waste-based anti-stripping agent for asphalt mixture, and preparation method and application thereof

Abstract

The application discloses a metallurgical solid waste-based anti-stripping agent for asphalt mixture as well as a preparation method and application thereof. 2 The specific surface area of the anti-stripping agent is greater than or equal to 600 m2 / g, and the anti-stripping agent comprises, in percentage by weight, 40-80% of modified desulfurization ash, 19-55% of modified steel slag powder and 1-5% of a surfactant. The content of the metallurgical solid waste in the anti-stripping agent is greater than 90%, the problem that metallurgical solid wastes such as desulfurization ash, steel slag and slag are difficult to be comprehensively recycled is solved, and the environmental pollution of the metallurgical solid waste is alleviated. The method overcomes the problems of performance deficiency and low utilization rate of single solid waste by modifying the desulfurization ash and the steel slag, and can save production cost, simplify the production process and improve the anti-stripping performance of the asphalt mixture.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of road engineering materials and metallurgical solid waste recycling, and more particularly relates to a metallurgical solid waste-based asphalt mixture anti-stripping agent and a preparation method and application thereof. BACKGROUND

[0002] Water damage is one of the key problems affecting the long-term service performance of asphalt pavement. After water penetrates into the asphalt mixture, it destroys the bonding interface between asphalt and aggregate under the repeated action of temperature changes and traffic loads, leading to asphalt film peeling, and a series of diseases such as aggregate exposure, loose, and potholes. Especially for acidic aggregate (such as granite, andesite), which is rich in hydrophilic groups such as silanol groups (Si-OH), the adhesion to asphalt is naturally poor, and water absorption easily leads to asphalt film peeling. After the pavement suffers water damage, the structural strength and safety of the pavement are reduced, and the maintenance cost of the pavement is high. In order to improve the water damage resistance of asphalt mixture, anti-stripping agents are generally added to asphalt mixture in road engineering to improve the adhesion and interface stability of asphalt and aggregate.

[0003] Commonly used anti-stripping agents include inorganic anti-stripping agents (such as slaked lime, cement), amine anti-stripping agents, and non-amine polymer anti-stripping agents, with slaked lime being the main one in practical application. The Ca²⁺ and OH⁻ in slaked lime (Ca(OH)2) or cement react with H⁺ on the surface of acidic aggregate to neutralize the surface acidity of the aggregate, generating stable compounds such as calcium silicate (CaSiO3) or calcium aluminate (CaAl2O4), which in turn improves the adhesion of the aggregate to the asphalt. However, adding excessive alkaline substances can easily make the asphalt mixture brittle, reducing the low-temperature crack resistance, and there are also problems of high cost and limited natural exploitation. Amine anti-stripping agents combine with acidic aggregate through hydrophilic amino groups and combine with asphalt through lipophilic groups, thereby achieving anti-stripping effect. However, it has poor high-temperature resistance, significant adhesion decline after aging, and high raw material cost. Non-amine polymer anti-stripping agents form stable silicon-oxygen bonds (Si-O) through chemical bonding between active groups (such as hydroxyl groups and carboxyl groups) on the molecular chain and Si-OH on the surface of acidic aggregate, converting the hydrophilic surface of acidic aggregate into a hydrophobic surface to form a hydrophobic film, thereby reducing water penetration and the risk of water damage to the pavement. Moreover, some anti-stripping agents also have environmental pollution risks and other problems, making it difficult to meet the demand for green and low-carbon transportation development. Therefore, there is an urgent need to develop new asphalt mixture anti-stripping agents with stable performance and green and low carbon.

[0004] At present, a large amount of solid waste will be produced in the process of steel smelting and flue gas desulfurization, among which the large solid waste represented by steel slag, slag and desulfurization ash has huge output. If it cannot be effectively disposed, it will not only occupy land resources, but also cause potential threat to the ecological environment. Steel slag and slag contain various active or potential active components, which have cementation potential; and desulfurization ash is usually alkaline, contains certain calcium-based or magnesium-based components, and has the ability to adjust the pH value of the system and improve the interface reaction environment. Although these metallurgical solid wastes have similar characteristics with cement and lime, which makes it possible to functionally utilize them in road materials. But in the existing technology, different metallurgical solid wastes are generally used separately to prepare asphalt anti-stripping agent, which cannot maximize the comprehensive utilization of these metallurgical solid wastes. For example, patent CN108373283A uses steel slag tailings, lime, fly ash and active agent to prepare asphalt mixture anti-stripping agent, and patent CN105645452A only uses desulfurization ash to prepare asphalt anti-stripping agent. But there is a problem of insufficient alkalinity of desulfurization ash itself when used to prepare asphalt anti-stripping agent. Although steel slag contains a certain amount of alkaline substances (such as CaO, MgO, etc.) and active substances, if the unmodified steel slag is directly added to the desulfurization ash, due to the dense surface structure of the steel slag and the existence of a large number of crystalline phases in the steel slag itself, the hydration activity is poor (i.e. the ability of steel slag to react with water to generate cementitious substances is poor), and it is difficult to form a stable bonding interface with asphalt. Therefore, how to improve the anti-stripping performance of asphalt mixture while improving the comprehensive utilization rate of metallurgical solid waste resources has become a problem that needs to be solved in this field, especially to realize the preparation of metallurgical solid waste such as desulfurization ash and steel slag into asphalt mixture anti-stripping agent with stable performance and the ability to adjust the interface and enhance the adhesion of aggregate and asphalt. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a kind of based on metallurgical solid waste's asphalt mixture anti-stripping agent and its preparation method and application, its purpose is to modify desulfurization ash and steel slag raw materials, wherein desulfurization ash is modified by high temperature calcination to convert calcium sulfate dihydrate into semi-hydrated calcium sulfate and / or anhydrous calcium sulfate that is easy to hydrate, and the particle size of modified steel slag and granulated blast furnace slag is ≤100 microns, the specific surface area of the anti-stripping agent obtained by uniformly mixing 40~80% of modified desulfurization ash, 19~55% of modified steel slag powder and 1~5% of surfactant is ≥600m 2 / kg, thereby solving the technical problems that the alkalinity of desulfurization ash itself is not enough when used to prepare asphalt anti-stripping agent, and the hydration activity of steel slag raw material is poor, making it difficult to jointly use desulfurization ash and steel slag raw material to prepare asphalt mixture anti-stripping agent.

[0006] To achieve the above purpose, according to one aspect of the present application, a kind of based on metallurgical solid waste's asphalt mixture anti-stripping agent is provided, the specific surface area of the anti-stripping agent is ≥600m 2 / kg, by weight percent, including modified desulfurization ash 40-80%, modified steel slag powder 19-55%, and surfactant 1-5%;

[0007] The modified desulfurization ash is desulfurization ash that is physically modified to convert calcium sulfate dihydrate into semi-hydrated calcium sulfate and / or anhydrous calcium sulfate;

[0008] The modified steel slag powder is a micro-powder having a particle size of ≤100 microns obtained by modifying steel slag and granulated blast furnace slag; by mass ratio, the modified steel slag powder includes 40-60% steel slag, 32-45% granulated blast furnace slag, and 3-7% modifier. In some embodiments, the components of the surfactant include triethanolamine, polyethylene glycol, polyacrylamide, anhydrous ethanol, and sodium dodecyl phosphate.

[0009] Preferably, the asphalt mixture anti-stripping agent, the steel slag is low alkalinity steel slag, and the modifier is alkali metal hydroxide or alkali metal carbonate.

[0010] Preferably, the asphalt mixture anti-stripping agent, 90% of the sample particle size of the modified steel slag powder is ≤60 microns.

[0011] Preferably, the asphalt mixture anti-stripping agent, the modified desulfurization ash is desulfurization ash obtained by modifying desulfurization ash from which free water is removed by calcination at a high temperature of 220-300°C for 30 minutes or more.

[0012] Preferably, the asphalt mixture anti-stripping agent, the surfactant is a mixture of triethanolamine, polyethylene glycol, polyacrylamide, anhydrous ethanol, and sodium dodecyl phosphate in a mass ratio of 1:1:2:1:1.

[0013] Preferably, the asphalt mixture anti-stripping agent, by weight percent, includes modified desulfurization ash 60-80%, modified steel slag powder 19-40%, and surfactant 1-3%.

[0014] According to another aspect of the present application, a preparation method of an asphalt mixture anti-stripping agent is also provided, the asphalt mixture anti-stripping agent being the anti-stripping agent as described in the present application, and the preparation method being prepared according to the following steps:

[0015] (1) Desulfurization ash modification: after the desulfurization ash raw material is dried to remove free water, high-temperature calcination is used to convert calcium sulfate dihydrate into semi-hydrated calcium sulfate and / or anhydrous calcium sulfate, to obtain modified desulfurization ash;

[0016] (2) Steel slag modification: by mass percent, 40-60% steel slag raw material, 32-45% granulated blast furnace slag, and 3-7% modifier are mixed, and ball-milled to a particle size of ≤100 microns, to obtain modified steel slag powder; the modifier is alkali metal hydroxide or alkali metal carbonate.

[0017] (3) The anti-stripping agent for asphalt mixture is prepared by mixing 40-80% of the modified desulfurization ash, 19-55% of the modified steel slag powder and 1-5% of the surfactant in percentage by mass, and high-speed ball milling into micro powder with specific surface area of ≥600 m2 / kg.

[0018] Preferably, the preparation method, in step (1), the high-temperature calcination temperature is 220-300℃, and the calcination time is 30 min or more; in step (2), the ball milling speed is 100-200 r / min, and the ball milling time is 60 min or more; in step (3), the high-speed ball milling speed is 500-1000 r / min, and the ball milling time is 10-30 min.

[0019] According to another aspect of the present application, the anti-stripping agent as described in the present application is also provided for use in preparing water-damage-resistant asphalt mixture, which is added as an admixture or as a filler substitute, wherein the anti-stripping agent is added as an admixture in an amount of 1-5% of the mass of the asphalt mixture; and the anti-stripping agent is added as a filler substitute by replacing the filler with the same mass to heat-mix with the asphalt and aggregate.

[0020] According to another aspect of the present application, the anti-stripping agent as described in the present application is also provided for use in preparing water-damage-resistant asphalt mixture, which is added as an admixture or as a filler substitute, wherein the anti-stripping agent is added as an admixture in an amount of 1-5% of the mass of the asphalt mixture; and the anti-stripping agent is added as a filler substitute by replacing the filler with the same mass to heat-mix with the asphalt and aggregate.

[0021] The principle of the present application is that the desulfurization ash is modified by calcination to convert calcium sulfate dihydrate into semi-hydrated calcium sulfate and anhydrous calcium sulfate, which can absorb part of the water to generate calcium sulfate dihydrate in the process of water intrusion into the asphalt, and the calcium sulfate dihydrate whiskers form a columnar shape to form an anchoring effect and strengthen the performance of the asphalt mixture. The modified desulfurization ash contains a large amount of calcium sulfate and calcium carbonate and a small amount of calcium hydroxide, which can provide an alkaline environment and fill the voids.

[0022] The modified steel slag powder is obtained by modifying the steel slag, granulated blast furnace slag and modifier to obtain the modified steel slag powder with a particle size of ≤100 microns. It is found that the hydration activity of the active substances such as CaO, SiO2 and Al2O3 contained in the steel slag itself can be improved at this particle size. Under the chemical activation of the modifier such as alkali metal hydroxide or alkali metal carbonate and the physical activation of the ball milling process, on the one hand, the inert crystalline phase in the steel slag is deconstructed and reconstructed to form more active mineral phases; on the other hand, the steel slag powder has finer particle size and larger specific surface area, thereby helping to improve the contact area between the asphalt and the aggregate. The hydration product generated by the hydration reaction of the steel slag powder and water in the alkaline environment can form a rigid transition layer at the interface of the asphalt and the aggregate, thereby improving the interfacial bonding strength and the overall stability of the mixture. The added granulated blast furnace slag provides additional silicate active components, further enhancing the hydration activity of the modified steel slag powder and the overall anti-stripping agent.

[0023] When the modified desulfurization ash and the modified steel slag powder are subjected to secondary high-speed ball milling to prepare the anti-stripping agent, under the action of the surfactant, the secondary high-speed ball milling can increase the fineness of the overall anti-stripping agent, enhance its dispersibility in the asphalt, and further strengthen the adhesion between the asphalt and the aggregate.

[0024] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects by preparing the asphalt mixture anti-stripping agent from the modified desulfurization ash and low-alkalinity steel slag:

[0025] 1. The asphalt mixture anti-stripping agent provided by the present application can comprehensively utilize the unique properties of various metallurgical solid waste components, overcoming the performance deficiencies and low utilization rate of single solid waste. The various components play a synergistic role to significantly enhance the adhesion of asphalt and aggregate and improve the water damage resistance of asphalt mixture.

[0026] 2. The asphalt mixture anti-stripping agent provided by the present application can be used as an additive according to conventional anti-stripping agents, or directly used as a filler. The preparation of asphalt mixture can be carried out without adding natural fillers, thereby saving production costs and simplifying the production process while achieving the purpose of improving the anti-stripping performance of asphalt mixture.

[0027] 3. The content of metallurgical solid waste in the asphalt mixture anti-stripping agent provided by the present application exceeds 90%. The production and use process not only has low carbon emissions and low cost, but also solves the problem of resource utilization of metallurgical solid waste such as desulfurization ash, steel slag and slag, alleviates the environmental pollution of metallurgical solid waste, and realizes effective utilization. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the particle size distribution of the modified steel slag powder. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] The present application provides an anti-stripping agent for asphalt mixture prepared from metallurgical solid waste, which is in the form of micropowder, and has a specific surface area of ≥600 m 2 / kg, and contains, by weight percentage, modified desulfurization ash 40-80%, modified steel slag powder 19-55%, and surfactant 1-5%; the modified steel slag powder is a micropowder with a particle size of ≤100 microns obtained by physical and chemical modification of steel slag and granulated blast furnace slag; preferably, 90% of the sample particle size of the modified steel slag powder is ≤60 microns.

[0031] In some embodiments, the anti-stripping agent preferably contains modified desulfurization ash 60-80%, modified steel slag powder 19-40%, and surfactant 1-3%.

[0032] The modified steel slag powder contains, by mass ratio, 40-60% steel slag powder, 32-45% granulated blast furnace slag powder, and 3-7% modifier. The steel slag is low-alkalinity steel slag, and the modifier is an alkali metal hydroxide or an alkali metal carbonate, which is used to stimulate the hydration activity of the low-alkalinity steel slag. In some embodiments, the modified steel slag powder is prepared as follows:

[0033] The modified steel slag powder is obtained by mixing, by mass percentage, 40-60% steel slag raw material, 32-45% granulated blast furnace slag, and 3-7% modifier, and ball milling into micropowder with a particle size of ≤100 microns; preferably, 90% of the sample particle size of the modified steel slag powder is ≤60 microns.

[0034] In the present application, the modification of steel slag can be carried out by low-speed ball milling at a speed of 100-200 r / min. For example, in some embodiments, the steel slag raw material is a byproduct in the steelmaking process, and is low-alkalinity steel slag with a particle size of greater than 2.36 mm; the granulated blast furnace slag is a byproduct of blast furnace ironmaking, and has a particle size of greater than 2.36 mm; the low-speed ball milling is carried out at a speed of 100-200 r / min for 60 min or more. Both the steel slag and the granulated blast furnace slag are alkaline metallurgical solid waste, and the calcium ions therein can react with the acid in the asphalt to form alkaline earth metal soaps (such as Ca(C 17 H 35 COO)2), which have strong polarity and stability, and can form a chemical bonding layer on the surface of the aggregate; the alkalinity of the steel slag can neutralize the negative charge SiO2 -, reduce the competition adsorption of water molecules to the interface, but the hydration activity of the low-alkalinity steel slag without modification is low. Although the addition of alkali can stimulate the hydration activity of the steel slag, it needs to be noted that different alkali substances and their dosages will have different effects on the hydration activity. Therefore, in practical applications, appropriate alkali substances and dosages need to be selected according to specific conditions. In the present application, alkali metal hydroxides or alkali metal carbonates are used as the modifier, and the addition of 3-7% can stimulate the hydration activity of the low-alkalinity steel slag, and the ball milling is further combined to increase the hydration activity of the low-alkalinity steel slag.

[0035] Preferably, the modified steel slag further comprises lime powder, and the mass percentage of the lime powder is 5-8%.

[0036] The desulfurization ash is modified by high-temperature calcination to convert CaSO4·2H2O into CaSO4·0.5H2O and / or easily-hydrated CaSO4, and the desulfurization ash after the modification is the modified desulfurization ash. The easily-hydrated CaSO4·0.5H2O or easily-hydrated CaSO4 in the modified desulfurization ash reacts with the eroding water to generate CaSO4·2H2O whiskers in the process of water vapor erosion of asphalt, and the CaSO4·2H2O whiskers form anchoring effect in the form of columns, which can further improve the adhesion of the aggregate and asphalt, and is also beneficial to improving the high-temperature performance of the asphalt. In some embodiments, the modified desulfurization ash is obtained by high-temperature calcination of the desulfurization ash at 220-300℃ for more than 30 minutes.

[0037] In some embodiments, the surfactant is mixed according to the mass ratio of triethanolamine, polyethylene glycol, polyacrylamide, anhydrous ethanol and sodium dodecyl phosphate of 1:1:2:1:1.

[0038] The present application further provides a preparation method of the asphalt mixture anti-stripping agent, which comprises the following steps:

[0039] (1) Desulfurization ash modification: after the desulfurization ash raw material is dried to remove free water, high-temperature calcination is used to convert CaSO4·2H2O into CaSO4·0.5H2O and / or easily-hydrated CaSO4, and the modified desulfurization ash is obtained. In some embodiments, the temperature of the high-temperature calcination is 220-300℃, and the calcination time is more than 30 minutes.

[0040] (2) Steel slag modification: according to 40-60% steel slag raw material, 32-45% granulated blast furnace slag and 3-7% modifier, the mixture is ball milled to obtain modified steel slag powder with a particle size of ≤100 microns; the steel slag raw material is low-alkalinity steel slag, and the modifier is alkali metal hydroxide or alkali metal carbonate. In some embodiments, the steel slag modification adopts a rotation speed of 100-200 r / min, and the ball milling is more than 60 minutes.

[0041] (3) Preparation of asphalt mixture anti-stripping agent: by mass percentage, 40-80% modified desulfurization ash, 19-55% modified steel slag powder and 1-5% surfactant are mixed, wherein the sum of the mass percentages of the modified desulfurization ash, the modified steel slag powder and the surfactant is 100%, and high-speed ball milling is performed to form a micro-powder with a specific surface area ≥600 m 2 / kg, i.e. the asphalt mixture anti-stripping agent. In some embodiments, the high-speed ball milling is 500-1000 r / min, and the ball milling is performed for 10-30 min.

[0042] In the method, the desulfurization ash in step (1) is one or both of a dry desulfurization product or a semi-dry desulfurization product, which is modified by high-temperature calcination to convert calcium sulfate dihydrate (CaSO4·2H2O) into calcium sulfate hemihydrate (CaSO4·0.5H2O) and / or easily-hydrated anhydrous calcium sulfate. Compared with unmodified desulfurization ash, the modified desulfurization ash in the present application can significantly improve the water damage resistance of the anti-stripping agent. It is speculated that the reason may be that the semi-hydrated calcium sulfate or anhydrous calcium sulfate formed by calcination modification of the desulfurization ash can re-form calcium sulfate dihydrate crystals when it comes into contact with water, and the columnar calcium sulfate dihydrate crystals can play an anchoring role, thereby enhancing the water damage resistance of the asphalt mixture.

[0043] Under the dual action of chemical activation by an alkali metal hydroxide or an alkali metal carbonate and physical activation by ball milling in step (2), on the one hand, the inert crystalline phase in the steel slag is deconstructed and reconstructed to form more active mineral phases, for example, the crystalline phase in the steel slag can be converted into a glass phase in the process of ball milling, thereby improving the hydration activity of the modified steel slag powder; on the other hand, the internal active components of the steel slag can be precipitated to promote the hydration reaction with the invading water to generate cementitious substances, thereby enhancing the adhesion of the aggregate and the asphalt. In addition, the surface of the steel slag raw material particles is multi-angled and rough after modification, and the mechanical interlocking force between the steel slag and the asphalt is strong, thereby forming an anchoring effect and reducing the risk of interface peeling.

[0044] Fly ash is fine ash collected from flue gas after burning coal powder in a coal-fired power plant, mainly composed of SiO2 and Al2O3, and requires an external activator to exhibit activity. For example, in the patent CN108373283B, the fly ash undergoes hydration in an alkaline environment generated by lime and high-alkalinity electric furnace steel slag to form a compound with hydraulic cementitious properties. Granulated blast furnace slag is a fine granular glassy material produced by quenching molten slag discharged during blast furnace ironmaking, mainly composed of silicates and aluminosilicates, which can further enhance the hydration activity of the modified steel slag in the present application. Preferably, 5-8% of lime is added during the modification of the steel slag in step (2) and ball milling is performed simultaneously.

[0045] Step (3) can increase the fineness of the anti-stripping agent as a whole, enhance its dispersibility in the asphalt, and further strengthen the adhesion between the asphalt and the aggregate by high-speed ball milling under the action of the surfactant. The triethanolamine in the surfactant can prevent the aggregation of particles during the ball milling process, improve the flowability and density of the powder, and thus promote the hydration reaction of the active substances in the modified steel slag powder; the polyacrylamide is a high molecular polymer, the non-polar groups in the polyacrylamide have a strong affinity with the asphalt, and the polar groups have a strong affinity with the aggregate, so that the interfacial force between the aggregate and the asphalt can be further enhanced. The polyethylene glycol forms a flexible polymer layer on the surface of the particles by adsorption, thereby preventing the aggregation of the particles, and the sodium dodecyl phosphate is an anionic surfactant, so that the dispersibility of the anti-stripping agent in the asphalt is synergistically enhanced, and the water damage resistance of the asphalt mixture is improved.

[0046] In addition, the application further provides a use of the anti-stripping agent in the preparation of the water damage resistant asphalt mixture.

[0047] In the use, the anti-stripping agent is added as an admixture or as a filler substitute, wherein the anti-stripping agent is added as the admixture according to 1-5% of the mass of the asphalt mixture; and the anti-stripping agent is added as the filler substitute according to the equal mass of the filler to be replaced.

[0048] In addition, the application further provides a water damage resistant asphalt mixture, which comprises aggregate, asphalt and the anti-stripping agent.

[0049] The following is an example of desulfurized ash, which is a byproduct produced after removing sulfides (mainly sulfur dioxide) in flue gas generated during steel smelting by physical or chemical methods, and the main components include desulfurized gypsum (CaSO4·2H2O), calcium sulfite (CaSO3), calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3) and the like.

[0050] Steel slag is a byproduct in the steelmaking process, and its mineral composition is mainly tricalcium silicate, followed by dicalcium silicate, RO phase, etc. Steel slag is divided into alkaline steel slag and acidic steel slag according to the properties of molten slag, and can be divided into low-alkalinity steel slag, neutral steel slag and high-alkalinity steel slag according to the alkalinity. The steel slag used in the following examples is a low-alkalinity steel slag.

[0051] Granulated blast furnace slag is a fine granular glassy material formed by quenching the molten material with silicate and silico-aluminate as the main components obtained during the smelting of pig iron in a blast furnace, which is not crystallized. The granulated blast furnace slag is similar to the cement composition, which contains more than 95% of glass body and dicalcium silicate, calcium yellow long stone, wollastonite and the like.

[0052] Example 1 Preparation of anti-stripping agent for asphalt mixture using metallurgical solid waste

[0053] The steel slag used in this example is low alkalinity steel slag, and the particle size is 2.36-4.75 mm.

[0054] The specific preparation steps of the anti-stripping agent are as follows:

[0055] (1) Modification of desulfurization ash: 1000 g of desulfurization ash raw material was dried at 105°C for 2 h (to remove free water in free state), and then air was blown into the combustion furnace to calcine the calcium sulfate dihydrate in the desulfurization ash into semi-water calcium sulfate which is easy to hydrate and / or anhydrous calcium sulfate which is easy to hydrate, to obtain modified desulfurization ash. For example, the modified desulfurization ash can be obtained by calcining at 220-300°C for more than 30 min. In this example, the desulfurization ash was calcined at 300°C for 30 min to obtain the modified desulfurization ash.

[0056] (2) Modification of steel slag: granulated blast furnace slag and steel slag were first dried in an oven at 105°C for 2 h. According to the mixing ratio of 50% steel slag (500 g), 45% granulated blast furnace slag (450 g), and 5% modifier (50 g) (the modifier in this example is sodium hydroxide), the mixture was uniformly mixed and then ball milled in a horizontal ball mill at a speed of 150 r / min for 60 min to obtain modified steel slag powder. Laser particle size analyzer (high resolution particle size analyzer) was used for testing. The instrument model is Mastersizer3000 (Malvern ms3000), data acquisition rate is 10 kHz, red light source maximum 4 mW He-Ne, 632.8 nm, blue light source 10 mW LED, 470 nm, and the test results are as follows: concentration 0.0054%, span 1.217, consistency 0.375, D[3,2] 5.94 μm, D[4,3] 35.0 μm, DV(10) 14.9 μm, DV(50) 34.5 μm, DV(90) 56.9 μm, and the specific particle size classification is shown in Table 1. Figure 1

[0057] ​Data interpretation: D[4,3]: volume (weight) weighted average particle size; D[3,2]: area weighted average particle size; Dv(10), Dv(50), Dv(90): represent the cumulative value of the particle size volume distribution, indicating that 10%, 50%, 90% of the total sample volume in the sample is less than the particle size value. For example, Dv(50) is 5.80 μm, that is, 50% of the sample volume in the sample has a particle size less than 5.80 μm, so it is also called the median particle size. Under normal conditions, Dv(50) and D[4,3] are similar, and when the particle size distribution of the sample is asymmetric, the two will deviate. When the values of D[3,2] and D[4,3] are closer, it proves that the shape of the tested particle is more regular, and the particle size distribution is more concentrated. In this embodiment, the values of D[3,2] and D[4,3] are significantly different, indicating that the modified steel slag powder obtained has an irregular shape, and it is speculated that it has strong mechanical interlocking force with asphalt, can form an "anchoring effect", and is beneficial to reducing the risk of interface peeling.

[0058] (3) Preparation of anti-stripping agent for asphalt mixture: take modified desulfurization ash 400 g, modified steel slag powder 550 g, and surfactant 50 g. Mix the weighed powder and surfactant uniformly in a planetary ball mill at a speed of 600 r / min for 10-30 min to obtain a micropowder with a specific surface area greater than 600 m 2 / kg, that is, an anti-stripping agent for asphalt mixture, denoted as anti-stripping agent 1.

[0059] The surfactant in this embodiment is prepared according to the mass ratio of triethanolamine, polyethylene glycol, polyacrylamide, anhydrous ethanol, and sodium dodecyl phosphate of 1:1:2:1:1, wherein anhydrous ethanol is used as a solvent. Take triethanolamine 8.3 g, polyethylene glycol 8.3 g, polyacrylamide 16.6 g, anhydrous ethanol 8.3 g, and dodecyl phosphate 8.3 g to prepare.

[0060] This example also uses the obtained anti-stripping agent 1 to prepare an asphalt mixture. The asphalt mixture is an AC-13 mixture, and the gradation table is shown in Table 1. The oil stone ratio is 5%, and the specific operation is as follows:

[0061] The basalt aggregate kept at 180℃ for 4h is stirred with the asphalt at 155℃ in a mixer at 170℃ for 90s. The anti-stripping agent prepared above is added to the mixer in equal quality to replace the filler and stirred for 90s. The oil stone ratio is 5%, and the asphalt mixture (the mixture is an AC-13 mixture) is prepared.

[0062] Table 1 Synthesis gradation table of AC-13 mixture

[0063]

[0064] The ordinary asphalt mixture was prepared according to the same procedure and gradation, and no anti-stripping agent was added in the ordinary asphalt mixture, and the preparation procedure was as follows:

[0065] The basalt aggregate kept at 180℃ for 4h was stirred in a mixer at 170℃ for 90s with the asphalt at 155℃, and the filler was added and stirred in the mixer for 90s, and the oil aggregate ratio was 5%, and thus the ordinary asphalt mixture (the mixture was AC-13 mixture, and the gradation table was shown in Table 1) was prepared.

[0066] The ordinary asphalt mixture and the asphalt mixture added with the anti-stripping agent were numbered as 1# and 2# respectively.

[0067] Example 2

[0068] (1) Desulfurized ash modification: repeat example 1.

[0069] (2) Steel slag modification: repeat example 1.

[0070] (3) Preparation of anti-stripping agent: according to 60% of modified desulfurized ash, 37% of modified steel slag powder and 3% of surfactant by mass percentage, the mixture was ball milled into a micro powder (the ball milling conditions were repeated in example 1), and was recorded as anti-stripping agent 2.

[0071] Using the obtained anti-stripping agent 2, the asphalt mixture was prepared by repeating example 1.

[0072] Example 3

[0073] (1) Desulfurized ash modification: repeat example 1.

[0074] (2) Steel slag modification: repeat example 1.

[0075] (3) Preparation of anti-stripping agent: according to 80% of modified desulfurized ash, 19% of modified steel slag powder and 1% of surfactant, the mixture was ball milled into a micro powder, and the ball milling conditions were repeated in example 1, and was recorded as anti-stripping agent 3.

[0076] Using the obtained anti-stripping agent 3, the asphalt mixture was prepared by repeating example 1.

[0077] Example 4

[0078] (1) Desulfurized ash modification: repeat example 1.

[0079] (2) Steel slag modification: 600g of steel slag coarse material, 320g of granulated blast furnace slag and 30g of sodium hydroxide were mixed uniformly, and then ball milled in a horizontal ball mill at a speed of 150r / min for 60min to obtain modified steel slag powder.

[0080] (3) Preparation of anti-stripping agent: Mix 40% modified desulfurization ash, 55% modified steel slag powder and 5% surfactant, and then ball mill into micro powder. Repeat Example 1 and record it as anti-stripping agent 4.

[0081] Using the obtained anti-stripping agent 4, asphalt mixtures were prepared in the same manner as in Example 1.

[0082] Example 5

[0083] The obtained anti-stripping agent 4 was added to the asphalt mixture as an admixture, as follows:

[0084] Basalt aggregate that has been kept at 180℃ for 4 hours is mixed with asphalt at 155℃ in a mixing plant at 170℃ for 90 seconds. The prepared anti-stripping agent 4 is taken at 2% of the mass of the mixture (the sum of the mass of asphalt, hot-mix aggregate and filler) and mixed evenly with mineral powder. The mixture is then added to the mixing plant and stirred for 90 seconds to obtain the required asphalt mixture.

[0085] Example 6

[0086] (1) Desulfurization ash modification: Repeat Example 1.

[0087] (2) Steel slag modification: Granulated blast furnace slag and steel slag are first dried in an oven at 105℃ for 2 hours. The modified steel slag powder is prepared according to the following proportions: 40% (400g) steel slag, 45% (450g) granulated blast furnace slag, 8% (80g) lime, and 7% (70g) modifier (sodium hydroxide in this example). After being mixed evenly, the modified steel slag powder is obtained by ball milling in a horizontal ball mill at a speed of 150r / min for 60min.

[0088] (3) Preparation of anti-stripping agent: Repeat Example 1. Using the obtained anti-stripping agent, repeat Example 1 to prepare asphalt mixture.

[0089] To compare the effects of modified desulfurization ash, modified steel slag powder, and surfactants, the following comparative examples were conducted. The mixture prepared by adding the anti-stripping agent in the comparative examples is designated as #3.

[0090] Comparative Example 1

[0091] Example 1 was repeated, except that modified desulfurization ash was not added. The anti-stripping agent was composed of 91.7% (550g) modified steel slag powder and 8.3% (50g) surfactant by mass ratio. The mixture was ball-milled into micro powder, and the ball milling conditions were repeated in Example 1 to obtain the anti-stripping agent.

[0092] The obtained anti-stripping agent was used to prepare a mixture, which was numbered 3#.

[0093] Comparative Example 2

[0094] Repeat example 1, the difference is that no modified steel slag powder is added, that is, the anti-stripping agent component is modified desulfurization ash 88.9% (400g) and surfactant 11.1% (50g) by mass ratio, mixed and ball milled into powder, the ball milling conditions are repeated in example 1 to obtain the anti-stripping agent.

[0095] The mixture is prepared by using the obtained anti-stripping agent, and the mixture number is recorded as 3#.

[0096] Comparative example 3

[0097] Repeat example 1, the difference is that the desulfurization ash is not modified by calcination, and the anti-stripping agent component is unmodified desulfurization ash 40% (400g), modified steel slag powder 55% (550g) and surfactant 5% (50g) by mass ratio, mixed and ball milled into powder, the ball milling conditions are repeated in example 1 to obtain the anti-stripping agent.

[0098] The mixture is prepared by using the obtained anti-stripping agent, and the mixture number is recorded as 3#.

[0099] Comparative example 4

[0100] Repeat example 1, the difference is that no modifier is added to the steel slag powder, wherein the steel slag powder is prepared as follows:

[0101] Mix by mass ratio steel slag 43%, granulated blast furnace slag 48.4%, lime powder 8.6%, and ball mill to obtain steel slag powder; mix by mass ratio modified desulfurization ash 40%, steel slag powder 55% and surfactant 5%, and ball mill into powder, the ball milling conditions are repeated in example 1.

[0102] Comparative example 5

[0103] Repeat example 1, the difference is that no surfactant is added, that is, the anti-stripping agent component is modified desulfurization ash 42.1% (400g) and modified steel slag powder 57.9% (550g) by mass ratio, mixed and ball milled into powder, the ball milling conditions are repeated in example 1.

[0104] Test the residual stability, freeze-thaw splitting strength ratio and 60℃ immersion wheel tracking dynamic stability of the above mixtures 1#, 2# and 3# according to the test procedures of “Highway Engineering Asphalt and Asphalt Mixture Test Procedures” (JTGE20-2011). Among them, mixture 1# without adding anti-stripping agent is used as a control, and the residual stability, freeze-thaw splitting strength ratio and 60℃ immersion wheel tracking dynamic stability of mixture 2# prepared by adding the anti-stripping agent in the above examples are tested, and the results are shown in Table 2. Compare the effect of adding the anti-stripping agent in the above examples and comparative examples on the water damage resistance of asphalt mixture, and the results are shown in Table 3.

[0105] Table 2 Comparison of water stability performance of mixture after adding anti-stripping agent (average value, n=3)

[0106]

[0107] According to the specification requirements of T0709-2011 on the water stability performance of asphalt mixture: residual stability (%) > 80%, freeze-thaw splitting tensile strength ratio (%) > 75%.

[0108] As can be seen from Table 2, the residual stability of the asphalt mixture added with the anti-stripping agent is 96.36%~98.45%, compared with the ordinary asphalt mixture 1# without adding the anti-stripping agent, the residual stability of the asphalt mixture 2# prepared by adding the anti-stripping agent of the present application is increased by 14.12%~16.45%, and the freeze-thaw splitting tensile strength ratio is increased by 8.11%~11.61%, the residual stability and the freeze-thaw splitting strength ratio are significantly improved, which shows that the water stability of the asphalt mixture after adding the anti-stripping agent is obviously improved, and compared with the anti-stripping agent in the patent CN108373283B, the residual stability value of the mixture after adding the anti-stripping agent is higher. In addition, the anti-stripping agent can be used as a substitute for fillers, and can also be added as an external additive. The component ratio of the anti-stripping agent is modified desulfurization ash 40%~80%, modified steel slag powder 19%~55%, and surfactant 1%~5%; preferably the component ratio of the anti-stripping agent is modified desulfurization ash 60%~80%, modified steel slag powder 19%~40%, and surfactant 1%~3%.

[0109] Table 3 Effect of anti-stripping agent with different components on water damage resistance of asphalt mixture

[0110]

[0111] Note: mixture 2# adds the anti-stripping agent in the examples, and the filler is replaced by an equal amount; mixture 3# adds the anti-stripping agent in the comparative examples, and the filler is replaced by an equal amount.

[0112] As shown in Table 3, the residual stability of the asphalt mixture prepared by adding the anti-stripping agent of Comparative Example 1 (without adding modified desulfurization ash), Comparative Example 2 (without adding modified steel slag powder) and Comparative Example 5 (without adding surfactant) is 88.14%, 85% and 81.08% respectively, and the freeze-thaw splitting tensile strength ratio is 83.7%, 81.82% and 75.53% respectively. Among them, compared with Comparative Example 1, the residual stability and freeze-thaw splitting tensile strength ratio of the asphalt mixture in Example 1 are increased by 7.34% and 5.0% respectively, indicating that the addition of modified desulfurization ash in the anti-stripping agent is beneficial to improving the water damage resistance of the anti-stripping agent. Compared with Comparative Example 2, the residual stability and freeze-thaw splitting tensile strength ratio of the asphalt mixture in Example 1 are increased by 10.48% and 6.88% respectively; compared with Comparative Example 5, the residual stability and freeze-thaw splitting tensile strength ratio of the asphalt mixture in Example 1 are increased by 14.4% and 13.17% respectively. It can be seen that the addition of the above surfactant and modified steel slag powder can improve the water damage resistance of the anti-stripping agent.

[0113] As can be seen from the comparison between Comparative Example 1 and Comparative Example 3 (desulfurization ash is not modified), compared with the anti-stripping agent prepared by adding unmodified desulfurization ash, the residual stability of the asphalt mixture in Example 1 is increased by 13.59% and the freeze-thaw splitting tensile strength ratio is increased by 4.9% by adding the desulfurization ash modified by calcination. It can be seen that the desulfurization ash modified by calcination can significantly improve the water damage resistance of the anti-stripping agent.

[0114] It is easy for those skilled in the art to understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A metallurgical solid waste based anti-stripping agent for asphalt mixtures, characterized by, The specific surface area of the anti-stripping agent is ≥600 m 2 / kg, including modified desulfurization ash 40~80%, modified steel slag powder 19~55%, and surfactant 1~5% by weight percentage; The modified desulfurization ash is obtained by modifying the desulfurization ash from which free water is removed by high-temperature calcination at 220-300 DEG C for 30 min or more, so that the calcium sulfate dihydrate is converted into calcium sulfate hemihydrate and / or calcium sulfate anhydrous; The modified steel slag powder is a micro-powder with a particle size of 100 microns or less obtained by modifying steel slag and granulated blast furnace slag, which comprises, by mass percentage, 40-60% steel slag, 32-45% granulated blast furnace slag and 3-7% modifier; the modifier is alkali metal hydroxide or alkali metal carbonate; The surfactant is a mixture of triethanolamine, polyethylene glycol, polyacrylamide, anhydrous ethanol and sodium dodecyl phosphate in a mass ratio of 1:1:2:1:

1.

2. The asphalt mixture anti-stripping agent of claim 1, wherein, The steel slag is low-alkalinity steel slag.

3. The asphalt mixture anti-stripping agent of claim 2, wherein, 90% of the sample particle size of the modified steel slag powder is 60 microns or less.

4. The asphalt mixture anti-stripping agent of claim 3, wherein, The anti-stripping agent comprises, by weight percentage, 60-80% modified desulfurization ash, 19-40% modified steel slag powder and 1-3% surfactant.

5. A method of preparing an anti-stripping agent for asphalt mixtures, characterized in that, The asphalt mixture anti-stripping agent is the anti-stripping agent according to any one of claims 1 to 3, which is prepared by the following steps: (1) desulfurization ash modification: after the desulfurization ash raw material is dried to remove free water, high-temperature calcination is used to convert the calcium sulfate dihydrate into calcium sulfate hemihydrate and / or calcium sulfate anhydrous, so as to obtain modified desulfurization ash; (2) steel slag modification: a mixture comprising, by mass percentage, 40-60% steel slag, 32-45% granulated blast furnace slag and 3-7% modifier is ball milled to a particle size of 100 microns or less to obtain modified steel slag powder; the modifier is alkali metal hydroxide or alkali metal carbonate; (3) The anti-stripping agent for asphalt mixture is prepared by mixing 40-80% of modified desulfurization ash, 19-55% of modified steel slag powder and 1-5% of surfactant by mass percentage, and high-speed ball milling into micro powder with specific surface area ≥600m 2 / kg.

6. The production method according to claim 5, wherein In step (1), the high-temperature calcination temperature is 220-300 DEG C, and the calcination time is 30 min or more; in step (2), the ball milling speed is 100-200 r / min, and the ball milling time is 60 min or more; in step (3), the high-speed ball milling speed is 500-1000 r / min, and the ball milling time is 10-30 min.

7. Use of an anti-stripping agent as claimed in any one of claims 1 to 4 for the preparation of a water-damaged asphalt mixture, characterized in that, The anti-stripping agent is added as an admixture or as a filler replacement, wherein the anti-stripping agent is added as an admixture at 1-5% of the mass of the asphalt mixture; the anti-stripping agent is added as a filler replacement by replacing the filler with an equal mass of the anti-stripping agent, and then hot mixing with asphalt and aggregate.

8. A water-damaged asphalt mixture, characterized by The anti-stripping agent comprises aggregate, asphalt and the anti-stripping agent according to any one of claims 1 to 4.

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