A method for preparing road water-stabilizing layer filler based on steel slag recycling

Abstract

The present invention provides a method for preparing a road water-stabilizing layer filler based on recycled steel slag, belonging to the technical field of steel slag reuse. The method comprises the following steps: S1, pretreatment of the steel slag; S2, modification of the steel slag; S3, preparation of the filler; and S4, shaping and compaction. The road water-stabilizing layer filler of the present invention is made by recycling steel slag as a basic raw material, thereby solving the environmental pollution problem that may be caused by improper treatment of steel slag and reducing the cost of road construction. The steel slag of the present invention is pretreated and modified on the existing basis, thereby overcoming the potential volume expansion of the steel slag and avoiding the local expansion hazard when applied to the road base layer. The compressive strength and flexural strength of the road water-stabilizing layer filler are improved, and the overall water permeability is excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of steel slag recycling, and in particular is a method for preparing a road water-stabilizing layer filler based on steel slag recycling. Background Art

[0002] Steel slag is an industrial byproduct produced during the steelmaking process. It primarily consists of silicates, calcium oxide, magnesium oxide, aluminum oxide, and small amounts of sulfides and phosphides. The recycling of steel slag is crucial, not only reducing environmental pollution but also transforming it into a valuable resource.

[0003] Steel slag can be crushed and screened before being used as a base or surface material for roads. Due to its excellent mechanical properties and durability, road materials made from steel slag can improve the load-bearing capacity and service life of roads. Using steel slag as a road construction material reduces raw material procurement costs and slag handling and disposal expenses, resulting in economic benefits for both businesses and society. The recycling of steel slag aligns with the principles of green development and a circular economy, and contributes to the sustainable development of the construction industry and materials science.

[0004] Therefore, there is an urgent need for a method for preparing road water-stabilizing layer filler based on steel slag recycling. The existing preparation method has the following defects: the steel slag is crushed into a uniform particle size, which easily leads to poor overall density of the prepared filler. At the same time, the steel slag is prone to volume expansion, and local expansion hazards will occur when applied to the road base, and the overall water permeability of the prepared road water-stabilizing layer filler is poor. Summary of the Invention

[0005] In response to the above-mentioned problems, the present invention provides a method for preparing road water-stabilizing layer filler based on steel slag recycling.

[0006] The technical solution of the present invention is: a method for preparing a road water-stabilizing layer filler based on steel slag recycling, comprising the following steps:

[0007] S1. Pretreatment of steel slag

[0008] First, rinse the steel slag with tap water and then dry it to obtain a clean steel slag base material. After the steel slag base material is crushed by a crusher, it is placed in a carbonization box for carbonization treatment for 45-50 hours to obtain steel carbonized particles. Then, the steel carbonized particles are dried and ball milled until the specific surface area of ​​the steel carbonized particles is 150-180m 2 / kg;

[0009] S2. Modification of steel slag

[0010] The steel carbonized particles after ball milling, deionized water and fly ash are mixed in a mass ratio of 2:0.5 to 1:0.25, granulated and dried to obtain steel carbonized green balls, anhydrous ethanol, expanded glass beads and steel carbonized green balls are mixed in a mass ratio of 1:0.6:1, 1.2-1.5wt% of silane coupling agent is added thereto, the pH is adjusted to 7.5-8, and heat treatment is performed. After freeze drying, steel slag modified particles are obtained, and then the steel slag modified particles, silicone oil and formaldehyde are mixed in a weight ratio of 1:3:4. methyl acrylate is uniformly mixed to form a first premix, then deionized water, sodium dodecylbenzenesulfonate and sodium bicarbonate are uniformly mixed in a weight ratio of 8:3:0.2 to form a second premix, then the first premix and the second premix are mixed in a weight ratio of 1:2, ultrasonically finely emulsified at room temperature for 20-25 minutes, and 1-1.5wt% of azobisisobutyronitrile is added thereto, stirred uniformly, and placed in a water bath at a temperature of 80-85°C for 2-3 hours, and cooled to room temperature to obtain steel slag composite particles;

[0011] S3. Preparation of filler

[0012] According to parts by weight, 35-60 parts of steel slag composite particles, 5-15 parts of cement, 5-15 parts of granite powder, 3-5 parts of lime, and 30-50 parts of water are mixed until uniform, and heated at a temperature of 160-170° C. for 3-5 hours to obtain a filler blank. Then, the temperature is raised to 200-220° C., and 1-2 parts of a stabilizer are added to the filler blank. The filler blank is sheared for 10-15 minutes to obtain a filler pre-finished product. The temperature controlled at 160-170° C. refers to the initial temperature before the reaction, that is, at Before lime and water begin to react significantly and release heat, the purpose is to ensure that the mixed material can undergo preliminary heating treatment in a relatively stable temperature environment. During the heating process, cement will begin to hydrate after adding water, and lime (calcium oxide CaO) will react with water to form calcium hydroxide (Ca(OH)2). After heating to 200-220℃ and adding stabilizers, the above reaction will be further promoted, which will help improve the thermal stability and durability of the material. The shearing process will help break up the agglomerates inside the material, making it more uniform and fine.

[0013] S4, forming and compacting

[0014] The wheel rolling method is used to pre-press the filler pre-finished product 4-5 times, and finally, the direction is changed and rolled 5-10 times to obtain the filler finished product.

[0015] Furthermore, in step S1, the steel slag base material is crushed by a crusher, and then a vibrating screen is used to take steel slag particles with particle sizes in the ranges of 0.5-1.5 mm, 1.6-2.5 mm, and 2.6-4 mm, respectively. After spraying a water reducer on the surface of the steel slag particles in each particle size range, the particles are placed in a carbonization box. When the vacuum degree is -0.25 MPa, CO2 gas is introduced until the pressure in the carbonization box reaches 0.25 MPa. Then, carbonization treatment is performed to obtain steel carbonized particles.

[0016] Description: The steel slag base material is crushed into steel slag particles of different sizes. Steel slags of different sizes can be embedded in each other, which helps to improve the overall density of the mixture. Steel slags of various sizes can form a more complex skeleton structure after mixing, which helps to improve the bearing capacity and stability of the water-stabilizing layer filler. The crushed steel slag particles are carbonized, so that the active ingredients in the steel slag, such as calcium oxide, react with carbon dioxide to form calcium carbonate, thereby improving the stability and durability of the steel slag. The calcium carbonate generated during the carbonization process fills the gaps between the steel slag particles, increases the density of the material, and improves its compressive strength and flexural strength. During the carbonization treatment, spraying a water reducer on the surface of the steel slag particles can reduce the surface tension of water, making it easier for water to penetrate between the steel slag particles.

[0017] Furthermore, the water reducer is a polycarboxylic acid water reducer, selected from one of methacrylic acid, acrylic acid, acrylamide or hydroxypropyl methylcellulose.

[0018] Description: Polycarboxylate water reducer can significantly reduce the water content of concrete without affecting its workability, usually reducing water by 5% to 30%.

[0019] Furthermore, in step S2, the temperature of the deionized water is 60-90° C., and the silane coupling agent is MPS or ODMS.

[0020] Description: The temperature of deionized water is controlled within the range of 60-90℃. Through the pre-treatment of deionized water and steel carbonized particles in this temperature range, the generated hydration products can form a dense protective layer on the surface of steel slag, preventing further hydration of steel slag, improving the volume stability of steel slag, and gradually reducing the volume expansion of steel slag, thereby reducing the probability of local expansion hazards in the road base.

[0021] Furthermore, in step S3, the mixture of steel slag composite particles, cement, granite powder, lime and water is heated by a microwave + far infrared combination method, wherein the microwave + far infrared combination is performed in an intermittent heating manner.

[0022] Description: Microwave heating has the advantages of fast heating speed and uniform heating, and can quickly increase the temperature of the material; far-infrared heating transfers heat energy through infrared radiation, which is suitable for surface heating and deep heating. Microwave heating can promote the polarization and rapid movement of water molecules, accelerate the hydration reaction between cement and water, the digestion reaction between lime and water, and the hydration reaction between steel slag composite particles and granite powder and water. Far-infrared heating helps maintain the structural stability of the material, reduces the volume expansion and contraction caused by rapid hydration reaction, and helps reduce the risk of cracks in the road water-stabilizing layer filler.

[0023] Furthermore, the intermittent heating process is: heating with microwave for 35-40 seconds, cooling with a heat exchanger for 2-3 minutes, then heating with far infrared for 40-45 seconds, cooling with a heat exchanger for 2-3 minutes. This is one cycle, and the operation is repeated 3-4 times until the mixture of steel slag composite particles, cement, granite powder, lime and water is heated to 120-140° C., and finally, the mixture is kept warm for 30-35 minutes.

[0024] Description: By alternating between microwave and far-infrared heating, and utilizing the characteristics of microwave rapid heating and the advantages of far-infrared deep heating, it is possible to ensure more precise temperature control during the heating process, reduce volume expansion and contraction caused by rapid hydration reactions, improve heating efficiency, and ensure material quality. In the heating process, during the microwave + far-infrared intermittent heating process, in the first cycle of microwave heating, the mixture of lime and water will heat up rapidly and begin to chemically react. Subsequently, in the far-infrared heating stage, although the temperature drops slightly, the mixture of lime and water is still in a higher temperature range, so the reaction will continue. In the cooling stage between each microwave heating and far-infrared heating, the temperature of the mixture will decrease, which may slow down the reaction rate. However, due to the entire heating process The process is repeated, and the mixture as a whole is kept in a higher temperature range, which is sufficient to maintain the digestion process of lime and other related hydration reactions. After the entire intermittent heating process is completed, the 30-35 minute insulation step is to ensure that all reactions can be fully carried out, including the complete digestion of lime and the hydration reaction between cement and other components. During this time, even if the initial rapid reaction has been completed, the remaining reactants will continue to react, thereby ensuring that the mixture achieves the desired physical and chemical properties. Therefore, although the reaction of lime and water begins at the beginning of the heating process and will continue in subsequent heating cycles, the entire intermittent heating process is designed to be sufficient to ensure that the reaction of lime and water is complete and that the mixture eventually reaches a suitable hardened state.

[0025] Furthermore, the microwave frequency is 2.35-2.45 GHz, the far infrared wavelength is 50-80 μm, and the heating time is 1.2-1.5 hours.

[0026] Description: By precisely controlling the power, frequency and heating time of microwaves and far infrared, the heating process can be optimized and the risk of overheating and uneven heating can be reduced.

[0027] Furthermore, in step S4, the filler pre-finished product is subjected to a curing process before being pre-pressed. The curing process is as follows:

[0028] S4-1. Curing the filler blank at a temperature of 30-35°C for 12-13 hours;

[0029] S4-2, using steam curing, curing temperature of 95-100 ° C, curing time 3-4 hours, and then performing room temperature curing process again, and controlling the curing time to 5-6 hours, repeating the steam curing process, and alternating curing 2-3 times to obtain the finished filler curing product;

[0030] S4-3, spraying water on the filler curing product for 6-7 hours, and the amount of water sprayed is 12-13% of the weight of the filler curing product, and finally air-drying.

[0031] Description: The filler blank is cured in sections by alternating between room temperature curing and high-temperature steam curing. This combines the advantages of rapid hardening at high temperature with the effect of long-term stable curing at room temperature. It can reduce the rapid evaporation of water, avoid cracks on the road surface prepared by the filler, and improve the performance and quality of the filler blank.

[0032] Furthermore, when steam curing is performed in step S4-2, the steam heating rate is 4-5°C / min.

[0033] Note: By controlling the steam heating rate, it is possible to avoid the possibility of thermal stress inside the filler due to a too fast heating rate, thus avoiding cracks.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The road water-stabilizing layer filler of the present invention is made by recycling steel slag as a basic raw material, which solves the environmental pollution problem caused by improper treatment of steel slag and reduces the cost of road construction. The steel slag of the present invention is pretreated and modified on the existing basis, which overcomes the potential volume expansion of steel slag and avoids the local expansion hazard when applied to the road base. During the pretreatment, the steel slag is crushed into particles of various particle sizes in order to allow steel slag particles of various particle sizes to be embedded in each other, which helps to improve the overall density of the mixture. At the same time, the crushed steel slag particles are carbonized, which can make the active components in the steel slag, such as calcium oxide, react with carbon dioxide to generate calcium carbonate, thereby improving the stability and durability of the steel slag. The calcium carbonate generated during the carbonization process fills the steel slag. The gaps between the particles increase the density of the material and improve its compressive strength and flexural strength. During the modification treatment, deionized water and the steel carbonized particles can be prevented from further hydration, thereby reducing the expansion of the steel slag and improving the volume stability of the steel slag. After the steel slag is pretreated with fly ash, needle-shaped and spatial network products will be generated. At the same time, the products are wrapped on the surface of the steel slag to form a protective layer, which further reduces the expansion of the steel slag. The silane coupling agent can form a chemical bond bridge between the steel carbonized green balls and the expanded glass microspheres, thereby improving the compatibility and bonding strength of the two. At the same time, the expanded glass microspheres can form an open pore structure in the steel carbonized green balls. These pores provide channels for water, allowing water to pass through the steel slag composite particles, thereby improving the overall permeability of the road water-stabilizing layer filler. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0037] In order to further understand the content of the present invention, the present invention is described in detail below through examples.

[0038] Example 1

[0039] A method for preparing a road water-stabilizing layer filler based on steel slag recycling comprises the following steps:

[0040] S1. Pretreatment of steel slag

[0041] First, the steel slag is rinsed with tap water and then dried to obtain a clean steel slag base material. The steel slag base material is crushed by a crusher, and steel slag particles with particle sizes of 0.5 mm, 1.6 mm, and 2.6 mm are taken using a vibrating screen. After spraying a water reducer on the surface of the steel slag particles in each particle size range, the particles are placed in a carbonization box. When the vacuum degree is -0.25 MPa, CO2 gas is introduced until the pressure in the carbonization box reaches 0.25 MPa. The carbonization treatment is carried out for 45 hours to obtain steel carbonized particles. Then, the steel carbonized particles are dried and ball-milled until the specific surface area of ​​the steel carbonized particles is 150 m 2 / kg, washing the steel slag can remove harmful substances in the steel slag, such as heavy metals and sulfides, reducing environmental pollution and improving the resource utilization rate of the steel slag. The water reducer is methacrylic acid, and steel slag particles of various particle sizes can be interlocked, which helps to improve the overall density of the mixture. After mixing, a more complex skeleton structure can be formed, which helps to improve the bearing capacity and stability of the water-stabilizing layer filler. The crushed steel slag particles are carbonized, so that the active ingredients in the steel slag, such as calcium oxide, react with carbon dioxide to form calcium carbonate, thereby improving the stability and durability of the steel slag. The calcium carbonate generated during the carbonization process fills the gaps between the steel slag particles, increasing the density of the material and improving its compressive strength and flexural strength. During the carbonization process, spraying the water reducer on the surface of the steel slag particles can reduce the surface tension of water, making it easier for water to penetrate between the steel slag particles. When the carbonized steel particles are dried and ball-milled, the classifier can effectively separate the particles of various particle sizes, improving the grinding efficiency and particle uniformity, thereby achieving higher-precision grinding and improving the uniformity and sphericity of the particles.

[0042] S2. Modification of steel slag

[0043] The milled steel carbide particles, deionized water and fly ash were mixed in a mass ratio of 2:0.5:0.25, and stirred at a rate of 100 rpm for 10 hours, granulated and dried to obtain steel carbide green balls, wherein the temperature of the deionized water was 60°C. Then, anhydrous ethanol, expanded glass beads and steel carbide green balls were mixed in a mass ratio of 1:0.6:1. At the same time, MPS was added dropwise at a rate of 3 ml / min, and then ammonia was added to adjust the pH to 7.5. The mixture was mechanically stirred at room temperature. Stir for 9 hours and heat at 120°C for 1 hour. Then, after repeated alcohol washing twice, centrifugation at a rate of 9000r / min for 20 minutes, and freeze-drying, steel slag modified particles are obtained. The steel slag modified particles, silicone oil and methyl methacrylate are mixed uniformly in a weight ratio of 1:3:4 to form a first premix. Then, deionized water, sodium dodecylbenzene sulfonate and sodium bicarbonate are mixed uniformly in a weight ratio of 8:3:0.2 to form a second premix. Then, The first premix and the second premix are mixed in a weight ratio of 1:2, and then emulsified at room temperature for 2 hours, and then ultrasonically finely emulsified for 20 minutes, and 1wt% of azobisisobutyronitrile is added thereto, stirred evenly, and placed in a water bath at 80°C for 2 hours, and cooled to room temperature to obtain steel slag composite particles; the ball-milled steel carbonized particles are mixed with deionized water and fly ash, wherein the deionized water can prevent the steel carbonized particles from further hydration, thereby reducing the expansion of the steel slag, improving the volume stability of the steel slag, and the powder After fly ash pretreatment, coal ash steel slag will generate needle-shaped and spatial network products. At the same time, the products are wrapped around the surface of the steel slag to form a protective layer, which further reduces the expansion of the steel slag. Through the silane coupling agent, a chemical bond bridge can be formed between the steel carbonized green balls and the expanded glass microspheres, thereby improving the compatibility and bonding strength between the two. At the same time, the expanded glass microspheres can form an open pore structure in the steel carbonized green balls. These pores provide channels for moisture, allowing moisture to pass through the steel slag composite particles, thereby improving the overall permeability of the road water-stabilizing layer filler.

[0044] S3. Preparation of filler

[0045] 35 parts by weight of steel slag composite particles, 5 parts by weight of cement, 5 parts by weight of granite powder, 3 parts by weight of lime, and 30 parts by weight of water were mixed until uniform, and heated at 160° C. for 3 hours to obtain a filler preform. The mixture was then heated to 200° C., and 1 part by weight of polyvinyl alcohol was added to the filler preform. The mixture was then sheared for 10 minutes to obtain a filler preform.

[0046] S4, forming and compacting

[0047] The wheel rolling method is used to pre-press the filler pre-finished product 4 times, and finally, the direction is changed and rolled 5 times to obtain the filler finished product.

[0048] Example 2

[0049] A method for preparing a road water-stabilizing layer filler based on steel slag recycling comprises the following steps:

[0050] S1. Pretreatment of steel slag

[0051] First, the steel slag is rinsed with tap water and then dried to obtain a clean steel slag base material. The steel slag base material is crushed by a crusher, and steel slag particles with particle sizes of 1 mm, 2 mm, and 3.5 mm are respectively taken using a vibrating screen. After spraying a water reducer on the surface of the steel slag particles in each particle size range, the particles are placed in a carbonization box. When the vacuum degree is -0.25 MPa, CO2 gas is introduced until the pressure in the carbonization box reaches 0.25 MPa. The carbonization treatment is carried out for 48 hours to obtain steel carbonized particles. Then, the steel carbonized particles are dried and ball-milled until the specific surface area of ​​the steel carbonized particles is 170 m 2 / kg, washing the steel slag can remove harmful substances in the steel slag, such as heavy metals and sulfides, reducing environmental pollution and improving the resource utilization rate of the steel slag. The water reducer is methacrylic acid, and steel slag particles of various particle sizes can be interlocked, which helps to improve the overall density of the mixture. After mixing, a more complex skeleton structure can be formed, which helps to improve the bearing capacity and stability of the water-stabilizing layer filler. The crushed steel slag particles are carbonized, so that the active ingredients in the steel slag, such as calcium oxide, react with carbon dioxide to form calcium carbonate, thereby improving the stability and durability of the steel slag. The calcium carbonate generated during the carbonization process fills the gaps between the steel slag particles, increasing the density of the material and improving its compressive strength and flexural strength. During the carbonization process, spraying the water reducer on the surface of the steel slag particles can reduce the surface tension of water, making it easier for water to penetrate between the steel slag particles. When the carbonized steel particles are dried and ball-milled, the classifier can effectively separate the particles of various particle sizes, improving the grinding efficiency and particle uniformity, thereby achieving higher-precision grinding and improving the uniformity and sphericity of the particles.

[0052] S2. Modification of steel slag

[0053] The steel carbide particles after ball milling, deionized water and fly ash were mixed in a mass ratio of 2:0.8:0.25, and stirred at a rate of 130 rpm for 13 hours, granulated and dried to obtain steel carbide green balls, wherein the temperature of the deionized water was 75 ° C. Then, anhydrous ethanol, expanded glass beads and steel carbide green balls were mixed in a mass ratio of 1:0.6:1. At the same time, ODMS was added dropwise at a rate of 4 ml / min, and then ammonia was added to adjust the pH to 7.8. The mixture was mechanically stirred at room temperature. The mixture was stirred for 9.5 hours and heated at 135°C for 1.5 hours. After repeated alcohol washing for 3 times, the mixture was centrifuged at 9300 r / min for 25 minutes. After freeze-drying, the steel slag modified particles were obtained. The steel slag modified particles, silicone oil and methyl methacrylate were mixed in a weight ratio of 1:3:4 to form a first premix. Then, deionized water, sodium dodecylbenzene sulfonate and sodium bicarbonate were mixed in a weight ratio of 8:3:0.2 to form a second premix. Then, the first premix and the second premix are mixed, emulsified at room temperature for 2.5 hours, and then ultrasonically finely emulsified for 23 minutes, and 1.3 wt% of azobisisobutyronitrile is added thereto, stirred evenly, and placed in a water bath at 83°C for 2.5 hours. After cooling to room temperature, steel slag composite particles are obtained; the ball-milled steel carbonized particles are mixed with deionized water and fly ash, wherein the deionized water can prevent the steel carbonized particles from further hydration, thereby reducing the expansion of the steel slag and improving the volume stability of the steel slag. After fly ash pretreatment, fly ash steel slag will generate needle-shaped and spatial network products. At the same time, the products are wrapped around the surface of the steel slag to form a protective layer, which further reduces the expansion of the steel slag. Through the silane coupling agent, a chemical bond bridge can be formed between the steel carbonized green balls and the expanded glass microspheres, thereby improving the compatibility and bonding strength between the two. At the same time, the expanded glass microspheres can form an open pore structure in the steel carbonized green balls. These pores provide channels for moisture, allowing moisture to pass through the steel slag composite particles, thereby improving the overall permeability of the road water-stabilizing layer filler.

[0054] S3. Preparation of filler

[0055] 50 parts by weight of steel slag composite particles, 10 parts by weight of cement, 9 parts by weight of granite powder, 4 parts by weight of lime, and 33 parts by weight of water were mixed until uniformly mixed and heated at 165° C. for 4 hours to obtain a filler preform. The mixture was then heated to 210° C. and 1.5 parts by weight of polyvinyl alcohol was added to the filler preform. The mixture was then sheared for 13 minutes to obtain a filler preform.

[0056] S4, forming and compacting

[0057] The wheel rolling method is used to pre-press the filler pre-finished product 4 times, and finally, the direction is changed and rolled 8 times to obtain the filler finished product.

[0058] Example 3

[0059] A method for preparing a road water-stabilizing layer filler based on steel slag recycling comprises the following steps:

[0060] S1. Pretreatment of steel slag

[0061] First, the steel slag is rinsed with tap water and then dried to obtain a clean steel slag base material. The steel slag base material is crushed by a crusher, and steel slag particles with particle sizes of 1.5 mm, 2.5 mm, and 4 mm are taken using a vibrating screen. After spraying a water reducer on the surface of the steel slag particles in each particle size range, the particles are placed in a carbonization box. When the vacuum degree is -0.25 MPa, CO2 gas is introduced until the pressure in the carbonization box reaches 0.25 MPa. The carbonization treatment is carried out for 50 hours to obtain steel carbonized particles. Then, the steel carbonized particles are dried and ball-milled until the specific surface area of ​​the steel carbonized particles is 180 m 2 / kg, washing the steel slag can remove harmful substances in the steel slag, such as heavy metals and sulfides, reducing environmental pollution and improving the resource utilization rate of the steel slag. The water reducer is methacrylic acid, and steel slag particles of various particle sizes can be interlocked, which helps to improve the overall density of the mixture. After mixing, a more complex skeleton structure can be formed, which helps to improve the bearing capacity and stability of the water-stabilizing layer filler. The crushed steel slag particles are carbonized, so that the active ingredients in the steel slag, such as calcium oxide, react with carbon dioxide to form calcium carbonate, thereby improving the stability and durability of the steel slag. The calcium carbonate generated during the carbonization process fills the gaps between the steel slag particles, increasing the density of the material and improving its compressive strength and flexural strength. During the carbonization process, spraying the water reducer on the surface of the steel slag particles can reduce the surface tension of water, making it easier for water to penetrate between the steel slag particles. When the carbonized steel particles are dried and ball-milled, the classifier can effectively separate the particles of various particle sizes, improving the grinding efficiency and particle uniformity, thereby achieving higher-precision grinding and improving the uniformity and sphericity of the particles.

[0062] S2. Modification of steel slag

[0063] The milled steel carbide particles, deionized water and fly ash were mixed in a mass ratio of 2:1:0.25, and stirred at a rate of 150 rpm for 15 hours, granulated and dried to obtain steel carbide green balls, wherein the temperature of the deionized water was 90°C. Then, anhydrous ethanol, expanded glass beads and steel carbide green balls were mixed in a mass ratio of 1:0.6:1. At the same time, ODMS was added dropwise at a rate of 5 ml / min, and then ammonia was added to adjust the pH to 8. The mixture was mechanically stirred at room temperature. 10h, and heated at a temperature of 150 ° C for 2h, then, after repeated alcohol washing 4 times, centrifuged at a speed of 9500r / min for 30min, and freeze-dried to obtain steel slag modified particles, steel slag modified particles, silicone oil and methyl methacrylate were mixed uniformly in a weight ratio of 1:3:4 to form a first premix, then deionized water, sodium dodecylbenzene sulfonate and sodium bicarbonate were mixed uniformly in a weight ratio of 8:3:0.2 to form a second premix, and then After that, the first premix and the second premix are mixed, emulsified at room temperature for 3 hours, and then ultrasonically finely emulsified for 25 minutes, and 1.5wt% of azobisisobutyronitrile is added thereto, stirred evenly, and placed in a water bath at a temperature of 85°C for 3 hours. After cooling to room temperature, steel slag composite particles are obtained; the ball-milled steel carbonized particles are mixed with deionized water and fly ash, wherein the deionized water can prevent the steel carbonized particles from further hydration, thereby reducing the expansion of the steel slag and improving the volume stability of the steel slag, and the fly ash After being pretreated with fly ash, steel slag will generate needle-shaped and spatial network products. At the same time, the products are wrapped around the surface of the steel slag to form a protective layer, which further reduces the expansion of the steel slag. Through the silane coupling agent, a chemical bond bridge can be formed between the steel carbonized green balls and the expanded glass microspheres, thereby improving the compatibility and bonding strength between the two. At the same time, the expanded glass microspheres can form an open pore structure in the steel carbonized green balls. These pores provide channels for moisture, allowing moisture to pass through the steel slag composite particles, thereby improving the overall permeability of the road water-stabilizing layer filler.

[0064] S3. Preparation of filler

[0065] 60 parts by weight of steel slag composite particles, 15 parts by weight of cement, 15 parts by weight of granite powder, 5 parts by weight of lime, and 50 parts by weight of water were mixed until uniformly mixed and heated at 170° C. for 5 hours to obtain a filler preform. The mixture was then heated to 220° C. and simultaneously, 2 parts by weight of polyvinyl alcohol was added to the filler preform, followed by shearing for 15 minutes to obtain a filler preform.

[0066] S4, forming and compacting

[0067] The wheel rolling method is used to form the filler pre-finished product. First, the filler pre-finished product is pre-pressed 5 times. Finally, the direction is changed and rolled 10 times to obtain the filler finished product.

[0068] The water expansion rates of steel carbonized particles were tested for 2 days, 5 days, 10 days, and 15 days in deionized water at room temperature and at 60°C, 75°C, and 90°C as in Examples 1-3, to determine the variation of steel slag expansion under different water bath conditions. The variation of steel slag expansion under different water bath conditions was obtained by curve fitting, and a parameter table of the variation of steel carbonized particles expansion under different water bath conditions was obtained, as shown in Table 1:

[0069] Table 1: Parameters of the expansion characteristics of carbonized steel particles in deionized water at room temperature and the temperature of Examples 1-3

[0070]

[0071] Through the data analysis of Table 1, it is found that, taking the immersion age of 15 days as an example, the reduction effect of immersion at room temperature is the worst, and the expansion rate is still 0.55%. When the water temperature of 60°C in Example 1 is used, the expansion rate of the steel carburized particles is reduced by 0.1% compared with that at room temperature. When the water temperature of 75°C in Example 2 is used, the expansion rate of the steel carburized particles is reduced by 0.25% compared with that at 60°C. When the water temperature of 90°C in Example 3 is used, the expansion rate of the steel carburized particles is the lowest, which is 0.03%, and the effect of reducing the expansibility is significant. In summary, the effect of temperature on the expansibility is more significant. Under practical conditions, the temperature should be increased as much as possible to improve the expansion rate of the steel carburized particles, and the 90°C deionized water in Example 3 is the best.

[0072] Example 4

[0073] This embodiment differs from embodiment 3 in that:

[0074] In step S3, a microwave + far-infrared heating method is used to heat the mixture of steel slag composite particles, cement, granite powder, lime, and water. The microwave + far-infrared heating method is intermittent. During the heating process, the mixture is stirred using a built-in stirring device to ensure that the mixture is heated evenly inside and outside. In order to ensure that the mixture is evenly distributed in the microwave heating device and the far-infrared heating device, an automatic feeding system, such as a screw conveyor, a belt conveyor, or a vibrating feeder, is used to control the feed rate of the mixture to 25 g / s.

[0075] The intermittent heating process is as follows: microwave heating for 35 seconds, cooling by a heat exchanger for 2 minutes, then far-infrared heating for 40 seconds, and cooling by a heat exchanger for 2 minutes. This is one cycle, and this operation is repeated three times until the mixture of steel slag composite particles, cement, granite powder, lime and water is heated to 120°C. Finally, the mixture is kept warm for 30 minutes. The microwave heating equipment and far-infrared heating equipment used are both existing technologies; the microwave frequency is 2.35 GHz, the far-infrared wavelength is 50 μm, and the heating time is 1.2 hours.

[0076] Example 5

[0077] This embodiment differs from embodiment 3 in that:

[0078] In step S3, a microwave + far-infrared heating method is used to heat the mixture of steel slag composite particles, cement, granite powder, lime, and water. The microwave + far-infrared heating method is intermittent. During the heating process, the mixture is stirred using a built-in stirring device to ensure that the mixture is heated evenly inside and outside. In order to ensure that the mixture is evenly distributed in the microwave heating device and the far-infrared heating device, an automatic feeding system, such as a screw conveyor, a belt conveyor, or a vibrating feeder, is used to control the feed rate of the mixture to 28 g / s.

[0079] The intermittent heating process is as follows: microwave heating for 38 seconds, cooling by a heat exchanger for 2.5 minutes, then far-infrared heating for 43 seconds, and cooling by a heat exchanger for 2.5 minutes. This is one cycle, and the operation is repeated four times until the mixture of steel slag composite particles, cement, granite powder, lime and water is heated to 130°C. Finally, the mixture is kept warm for 33 minutes. The microwave heating equipment and far-infrared heating equipment used are both existing technologies; the microwave frequency is 2.4 GHz, the far-infrared wavelength is 60 μm, and the heating time is 1.3 hours.

[0080] Example 6

[0081] This embodiment differs from embodiment 3 in that:

[0082] In step S3, a microwave + far-infrared heating method is used to heat the mixture of steel slag composite particles, cement, granite powder, lime, and water. The microwave + far-infrared heating method is intermittent. During the heating process, the mixture is stirred using a built-in stirring device to ensure that the mixture is heated evenly inside and outside. In order to ensure that the mixture is evenly distributed in the microwave heating device and the far-infrared heating device, an automatic feeding system, such as a screw conveyor, a belt conveyor, or a vibrating feeder, is used to control the feed rate of the mixture to 30 g / s.

[0083] The intermittent heating process is as follows: microwave heating for 40 seconds, cooling by a heat exchanger for 3 minutes, then far-infrared heating for 45 seconds, and cooling by a heat exchanger for 3 minutes. This is one cycle, and the operation is repeated four times until the mixture of steel slag composite particles, cement, granite powder, lime and water is heated to 140°C. Finally, the mixture is kept warm for 35 minutes. The microwave heating equipment and far-infrared heating equipment used are both existing technologies; the microwave frequency is 2.45 GHz, the far-infrared wavelength is 80 μm, and the heating time is 1.5 hours.

[0084] On the basis of Example 3, the microwave + far-infrared combined heating method of Examples 4-6 was used to treat the mixture of steel slag composite particles, cement, granite powder, lime and water respectively to prepare a road water-stabilizing layer filler, and a pavement material strength tester was used to conduct an unconfined compressive strength test on the road water-stabilizing layer filler, wherein the unconfined compressive strength was calculated according to formula (1-1).

[0085]

[0086] Where: R C is the unconfined compressive strength (MPa), P is the maximum pressure at which the specimen fails (N), A is the cross-sectional area of ​​the specimen (mm), and A is calculated according to formula (1-2);

[0087]

[0088] Where: D is the diameter of the specimen (mm).

[0089] The unconfined compressive strength data of the road water-stabilizing layer filler were obtained, and the test results were recorded in Table 2.

[0090] Table 2: Unconfined compressive strength of road water-stabilizing layer fillers made from the mixtures treated by the heating methods of Examples 4-6

[0091] Example 4 Example 5 Example 6 <![CDATA[R C / MPa]]> 4.05 4.84 6.46

[0092] Through the data analysis of Table 2, it is found that the road water-stabilizing layer filler prepared by treating the mixture of steel slag composite particles, cement, granite powder, lime and water respectively using the microwave + far-infrared combined heating method of Example 6 has the highest unconfined compressive strength, while the unconfined compressive strength of the road water-stabilizing layer filler corresponding to the heating method of Example 5 is second, and the unconfined compressive strength of the road water-stabilizing layer filler corresponding to the heating method of Example 4 is the lowest. There is a close relationship between the generation of cracks in the road water-stabilizing layer filler and the unconfined compressive strength. Under normal circumstances, when the unconfined compressive strength of the filler is not sufficient to resist the effects of external loads or environmental factors (such as temperature changes, humidity changes, chemical erosion, etc.), cracks may occur. Therefore, the microwave + far-infrared combined heating method of Example 6 is the best effect on reducing cracks.

[0093] Example 7

[0094] This embodiment differs from embodiment 6 in that:

[0095] In step S4, the filler pre-finished product is subjected to curing treatment before pre-pressing. The curing process is as follows:

[0096] S4-1. Curing the filler blank at 30°C for 12 hours;

[0097] S4-2. Steam curing is performed at a temperature of 95° C. for 3 hours, followed by a room temperature curing process for 5 hours. The steam curing process is repeated twice, alternating between the two steps, to obtain a cured filler product. The steam heating rate is 4° C. / min. Before steam curing, the temperature of the filler preform should be raised to a temperature close to the steam temperature to reduce thermal shock caused by sudden temperature changes. Furthermore, before the filler preform, which has been cured at room temperature, is placed in a high-temperature steam environment, the humidity of the filler preform should be ensured to match that of the steam curing environment to avoid shrinkage or expansion caused by humidity differences.

[0098] S4-3. Spray water on the filler curing product for 6 hours, and the amount of water sprayed is 12% of the weight of the filler curing product, and finally air dry.

[0099] Example 8

[0100] This embodiment differs from embodiment 6 in that:

[0101] In step S4, the filler pre-finished product is subjected to curing treatment before pre-pressing. The curing process is as follows:

[0102] S4-1. Curing the filler blank at 33°C for 12.5 hours;

[0103] S4-2. Steam curing is performed at a temperature of 98° C. for 3.5 hours. Then, a room temperature curing process is performed again, with the curing time controlled to 5.5 hours. The steam curing process is repeated three times in alternating fashion to obtain a cured filler product. The steam heating rate is 4.5° C. / min. Before steam curing, the temperature of the filler preform should be raised to a temperature close to the steam temperature to reduce thermal shock caused by sudden temperature changes. Furthermore, before the filler preform, which has been cured at room temperature, is introduced into the high-temperature steam environment, the humidity of the filler preform should be ensured to match that of the steam curing environment to avoid shrinkage or expansion problems caused by humidity differences.

[0104] S4-3. Spray water on the filler curing product for 6.5 hours, and the amount of water sprayed is 12.5% ​​of the weight of the filler curing product, and finally air dry.

[0105] Example 9

[0106] This embodiment differs from embodiment 6 in that:

[0107] In step S4, the filler pre-finished product is subjected to curing treatment before pre-pressing. The curing process is as follows:

[0108] S4-1. Curing the filler blank at 35°C for 13 hours;

[0109] S4-2. Steam curing is performed at a temperature of 100° C. for 4 hours, followed by a room temperature curing process for 6 hours. The steam curing process is repeated three times to obtain a cured filler product. The steam heating rate is 5° C. / min. Before steam curing, the temperature of the filler preform should be raised to a temperature close to the steam temperature to reduce thermal shock caused by sudden temperature changes. At the same time, before the filler preform, which has been cured at room temperature, is placed in a high-temperature steam environment, the humidity of the filler preform should be ensured to match that of the steam curing environment to avoid shrinkage or expansion caused by humidity differences.

[0110] S4-3. Spray water on the filler curing product for 7 hours, and the amount of water sprayed is 13% of the weight of the filler curing product, and finally air dry.

[0111] On the basis of Example 6, the unconfined compressive strength test of the road water-stabilizing layer filler was carried out on the filler pre-finished products that had undergone the maintenance treatment of Examples 7-9 using a pavement material strength tester, wherein the unconfined compressive strength was calculated according to formula (1-1).

[0112] Example 7 Example 8 Example 9 <![CDATA[R C / MPa]]> 7.52 7.68 8.03

[0113] Through the data analysis of Table 2, it is found that after the filler pre-finished product is treated with the curing treatment method of Example 9, the unconfined compressive strength of the filler pre-finished product is the largest, and after the filler pre-finished product is treated with the curing treatment method of Example 8, the unconfined compressive strength of the filler pre-finished product is second, and after the filler pre-finished product is treated with the curing treatment method of Example 7, the unconfined compressive strength of the filler pre-finished product is the smallest. Therefore, the curing treatment method of Example 9 has the best effect on reducing cracks, and therefore, Example 9 is the best embodiment.

Claims

1. A method for preparing road water-stabilizing layer filler based on steel slag recycling, characterized in that: The following steps are involved: S1. Pretreatment of steel slag First, rinse the steel slag with tap water and then dry it to obtain a clean steel slag base material. After the steel slag base material is crushed by a crusher, it is placed in a carbonization box for carbonization treatment for 45-50 hours to obtain steel carbonized particles. Then, the steel carbonized particles are dried and ball milled until the specific surface area of ​​the steel carbonized particles is 150-180m 2 / kg; S2. Modification of steel slag The steel carbonized particles after ball milling, deionized water and fly ash are mixed in a mass ratio of 2:0.5 to 1:0.25, granulated and dried to obtain steel carbonized green balls, anhydrous ethanol, expanded glass beads and steel carbonized green balls are mixed in a mass ratio of 1:0.6:1, 1.2-1.5wt% of silane coupling agent is added thereto, the pH is adjusted to 7.5-8, and heat treatment is performed. After freeze drying, steel slag modified particles are obtained, and then the steel slag modified particles, silicone oil and formaldehyde are mixed in a weight ratio of 1:3:

4. methyl acrylate is uniformly mixed to form a first premix, then deionized water, sodium dodecylbenzenesulfonate and sodium bicarbonate are uniformly mixed in a weight ratio of 8:3:0.2 to form a second premix, then the first premix and the second premix are mixed in a weight ratio of 1:2, ultrasonically finely emulsified at room temperature for 20-25 minutes, and 1-1.5wt% of azobisisobutyronitrile is added thereto, stirred evenly, and placed in a water bath at a temperature of 80-85°C for 2-3 hours, and cooled to room temperature to obtain steel slag composite particles; S3. Preparation of filler 35-60 parts by weight of steel slag composite particles, 5-15 parts of cement, 5-15 parts of granite powder, 3-5 parts of lime, and 30-50 parts of water are mixed until uniform, and heated at 160-170° C. for 3-5 hours to obtain a filler preform. The temperature is then raised to 200-220° C., 1-2 parts of a stabilizer is added to the filler preform, and the mixture is sheared for 10-15 minutes to obtain a filler preform. S4, forming and compacting The wheel rolling method is used to pre-press the filler pre-finished product 4-5 times, and finally, the direction is changed and rolled 5-10 times to obtain the filler finished product.

2. The method for preparing a road water-stabilizing layer filler based on steel slag recycling according to claim 1, characterized in that: In step S1, the steel slag base material is crushed by a crusher, and then a vibrating screen is used to take steel slag particles with particle sizes in the ranges of 0.5-1.5 mm, 1.6-2.5 mm, and 2.6-4 mm, respectively. After spraying a water reducer on the surface of the steel slag particles in each particle size range, the particles are placed in a carbonization box. When the vacuum degree is -0.25 MPa, CO2 gas is introduced until the pressure in the carbonization box reaches 0.25 MPa. Then, carbonization treatment is performed to obtain steel carbonized particles.

3. The method for preparing a road water-stabilizing layer filler based on steel slag recycling according to claim 1, characterized in that: In step S2, the temperature of the deionized water is 60-90° C., and the silane coupling agent is MPS or ODMS.

4. The method for preparing a road water-stabilizing layer filler based on steel slag recycling according to claim 1, characterized in that: In step S3, the mixture of steel slag composite particles, cement, granite powder, lime and water is heated by a microwave + far infrared combination method, wherein the microwave + far infrared combination is performed in an intermittent heating manner.

5. The method for preparing a road water-stabilizing layer filler based on steel slag recycling according to claim 4, characterized in that: The intermittent heating process is as follows: heating with microwaves for 35-40 seconds, cooling with a heat exchanger for 2-3 minutes, then heating with far infrared for 40-45 seconds, and cooling with a heat exchanger for 2-3 minutes. This constitutes one cycle, and the operation is repeated 3-4 times until the mixture of steel slag composite particles, cement, granite powder, lime and water is heated to 120-140° C., and finally, the mixture is kept warm for 30-35 minutes.

6. The method for preparing a road water-stabilizing layer filler based on steel slag recycling according to claim 5, characterized in that: The microwave frequency is 2.35-2.45 GHz, the far infrared wavelength is 50-80 μm, and the heating time is 1.2-1.5 h.

7. The method for preparing a road water-stabilizing layer filler based on steel slag recycling according to claim 1, characterized in that: In step S4, the filler pre-finished product is subjected to curing treatment before pre-pressing. The curing process is as follows: S4-1. Curing the filler blank at a temperature of 30-35°C for 12-13 hours; S4-2, using steam curing, curing temperature of 95-100 ° C, curing time 3-4 hours, and then performing room temperature curing process again, and controlling the curing time to 5-6 hours, repeating the steam curing process, and alternating curing 2-3 times to obtain the finished filler curing product; S4-3. Spray water on the filler curing product for 6-7 hours, and the amount of water sprayed is 12-13% of the weight of the filler curing product, and finally air dry.

8. The method for preparing a road water-stabilizing layer filler based on steel slag recycling according to claim 7, characterized in that: During steam curing in step S4-2, the steam heating rate is 4-5°C / min.

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