Artificial reef concrete preparation method
By crushing, screening, stabilizing, grinding, washing, granulating and curing steel slag, stable steel slag aggregate is prepared for use in artificial reef concrete. This solves the problems of low utilization rate and high cost of steel slag, and achieves efficient resource utilization and improved concrete performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CENT RES INST OF BUILDING & CONSTR CO LTD MCC GRP
- Filing Date
- 2026-03-25
- Publication Date
- 2026-06-05
AI Technical Summary
Steel slag has poor stability, resulting in low resource utilization rate. It cannot be used as aggregate and cementing material, causing storage pressure and environmental pollution. In addition, traditional artificial reef materials are expensive.
By crushing and screening steel slag, stabilizing pretreatment, grinding and washing, disc granulation and curing, fine and coarse aggregates of steel slag with good stability are prepared, and then mixed with cementitious materials to prepare artificial reef concrete.
It has enabled the large-scale and high-value utilization of steel slag, which meets the needs of artificial reefs, reduces costs, and improves the long-term mechanical properties and seawater compatibility of concrete, with a compressive strength retention rate of up to 95%.
Smart Images
Figure CN122145103A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metallurgical solid waste utilization, specifically to a method for preparing artificial reef concrete, and particularly to a method for preparing steel slag aggregate and artificial reef concrete based on the aggregate. Background Technology
[0002] my country has a long coastline and its near-shore ecological environment is severely damaged. Artificial reefs play a positive role in restoring and enhancing fishery resources, improving the near-shore ecological environment, and providing marine carbon sinks and ecological services. Therefore, my country has a large demand for artificial reefs. The 2023 national artificial reef construction plan indicates that an average of over 5 million cubic meters of reefs need to be deployed annually to restore the marine ecosystem. Traditional artificial reefs mainly use materials such as natural sand and gravel and ordinary concrete. The price of high-quality sand and gravel has soared from 30 yuan / ton in 2015 to 120 yuan / ton in 2024, resulting in significant material cost pressures. my country's crude steel production has exceeded 1 billion tons for many consecutive years, corresponding to an annual steel slag discharge of 120 million tons. However, its resource utilization rate is less than 30%, resulting in a cumulative steel slag stockpile exceeding 1.2 billion tons, causing land occupation and environmental pollution.
[0003] With the increasing demands for industrialization and ecological protection, the intersection of steel slag resource utilization and marine ecological restoration is becoming an important direction for technological innovation, and some scholars are attempting to use steel slag in marine engineering. Patent CN103159448A describes a method for preparing artificial reef concrete material using steel slag as the main raw material. Its characteristic is that the hot-quenched steel slag is directly crushed and screened and used as coarse aggregate, fine aggregate, and some cementitious material raw materials. However, since expansive substances such as free calcium oxide (f-CaO) exist in the coarse and fine aggregates, whether it is completely dissolved and its long-term mechanical properties remain to be confirmed. Patent CN105693168A describes a high-strength steel slag concrete for constructing artificial reefs. Its characteristic is that it only specifies the crushing value, bulk density, water absorption rate, alkalinity, and main minerals of the steel slag coarse aggregate. Similarly, it does not consider the dissolution of f-CaO in the aggregate and its impact on long-term mechanical properties. Patent CN107759174A describes a method for preparing artificial reef concrete using carbonated pre-cured steel slag. Its characteristic is that the fine aggregate and powder of steel slag are first pre-cured by carbonation before being used as aggregate in concrete and as raw materials for some cementitious materials. It does not involve content related to coarse aggregate in concrete. Patent CN120423836A describes a process for preparing high-performance concrete using artificial aggregate, characterized by using sintered steel slag as aggregate in concrete preparation. Patent CN120518344A describes a core-shell structured ceramsite, its preparation method, and its application. Its characteristic is that the core is 2.36~4.75mm biochar, and the outer shell is made of steel slag powder, glass powder, and cement. The volume ratio of the outer shell preparation materials to biochar is 0.5~2:1, and the outer shell thickness is 2mm. The preparation process includes three mixing steps. Furthermore, this patent does not perform stabilization treatment on the steel slag, and its long-term mechanical properties require further confirmation.
[0004] In summary, the pressure to process and utilize steel slag, the urgent need for marine ecological restoration, the limitations of traditional materials, and the inherent contradictions of steel slag itself constitute the technical background of this invention. Solving the bottleneck of steel slag's expansibility and achieving a precise match between it and the requirements of artificial reefs has become a key direction for overcoming the current technological predicament. Summary of the Invention
[0005] To address, or at least partially address, the problem of the difficulty in large-scale disposal of steel slag due to its poor stability and inability to be used as aggregate and cementing material, this invention provides a method for preparing artificial reef concrete. The method uses stabilized steel slag as fine aggregate, stabilized steel slag powder as the main raw material to prepare coarse aggregate, and cement or solid waste-based adhesives as cementing materials to prepare artificial reef concrete. This provides a systematic solution for the large-scale disposal of steel slag and the reduction of the cost of artificial reef concrete.
[0006] Therefore, the specific technical solution adopted by the present invention is as follows: A method for preparing artificial reef concrete includes the following steps: S1: Preparation of steel slag fine aggregate Steel slag is crushed and screened to obtain granular materials with a particle size of less than or equal to 4.75 mm and greater than 4.75 mm. The steel slag particles with a particle size of less than or equal to 4.75 mm are subjected to stabilization pretreatment, and then dried and screened to obtain steel slag fine aggregate with a particle size distribution between 0.15 and 4.75 mm. S2: Preparation of steel slag-based coarse aggregate S21: Crushing and grinding steel slag particles with a particle size greater than 4.75 mm to obtain a specific surface area of 350~500 m². 2 Steel slag powder with a concentration between / kg was pretreated by water washing and then dried to obtain steel slag powder with good stability. S22: After mixing the steel slag powder obtained in S21 with the cementitious binder, put it into the disc granulation equipment, adjust the process parameters of the disc granulation equipment, and spray water evenly into the disc granulation equipment at the same time. After completing the first granulation, the particles are screened and the particles that meet the preset particle size range are used for secondary granulation. S23: The particles obtained in S22 that meet the preset particle size range are subjected to secondary granulation. The binder used for secondary granulation is a mixture of cement and fly ash. The binder dosage is 30% to 50% of the particles that meet the preset particle size range. The process parameters of the disc granulator are the same as those in step S22. After secondary granulation, coarse aggregate with an outer pure binder shell is formed. S24: The coarse aggregate particles obtained by secondary granulation in step S23 are cured for the first time under the first preset temperature and humidity conditions, and then cured for the second time under the second preset temperature and humidity conditions to obtain steel slag coarse aggregate with good stability and mechanical properties. S3: Preparation of artificial reef concrete The fine steel slag aggregate obtained in S1 and the coarse steel slag aggregate obtained in S2 are mixed with cementitious materials in a preset ratio, and then water and admixtures are added. After mixing again, a uniform concrete mixture is obtained. The mixture is then made into a test mold and vibrated. After molding and demolding, it is cured for 28 days in an environment with a temperature of 20±2℃ and a humidity of more than 95% to obtain artificial reef concrete test blocks.
[0007] Optionally, before crushing and screening the steel slag in step S1, the method further includes: The steel slag is subjected to pressurized hot quenching or pool-type hot quenching process, and then magnetically separated to obtain steel slag with an iron content of less than 2.0%.
[0008] Optionally, the stabilization pretreatment conditions for the steel slag particles in step S1 are as follows: The treatment agent used is at least one of acetic acid, oxalic acid, citric acid, ammonium chloride, or water. The pH value of the treatment agent is in the range of 3 to 7. The liquid-solid ratio of the treatment agent to the steel slag particles is 1 to 10 L: 1 kg. The stabilization treatment time is 0.5 to 8 h. The stirring speed is 20 to 100 r / min. The number of treatments is based on the pH value of the last washing solution being between 5 and 8.
[0009] Optionally, the pretreatment conditions for the steel slag powder water washing in step S21 are as follows: The liquid-to-solid ratio of water to steel slag powder is 1~10L:1kg, the treatment time is 0.5~8h, the stirring speed is 20~100r / min, and the number of water washes is 2~5 times.
[0010] Optionally, in step S22, the mass ratio of steel slag powder to cementitious binder is 50~80:20~50, and the cementitious binder is lime and fly ash, with a mass ratio of lime to fly ash of 1:0.1~0.9. The process parameters for adjusting the disc granulation equipment include: setting the particle diameter to about 0.8m, the rotation speed to 35~55r / min, the tilt angle to 35°~55°, and the water spray volume to 20%~35% of the total mass of steel slag powder and cementitious binder, with the water sprayed in a mist form; After the first granulation is completed, particles with a diameter between 3 and 15 mm are screened out for secondary granulation.
[0011] Optionally, the cement used in the secondary granulation in step S23 is P·O42.5 cement, and the mass ratio of P·O42.5 cement to fly ash in the binder is 1:1.
[0012] Optionally, the first preset temperature and humidity conditions in step S24 include: temperature of 30~80℃, relative humidity of 95% or higher, and curing time of 10~20h; The second preset temperature and humidity conditions include: temperature of 18~22℃, relative humidity of 95% or higher, and curing time of 10~20 days.
[0013] Optionally, in step S3, the mass ratio of steel slag fine aggregate, steel slag coarse aggregate, cementitious material, water, and admixture is 20~35:44~55:20~35:4~17.5:0.02~0.14. The admixture is a polycarboxylate superplasticizer, and the cementitious material is P·O42.5 cement or a solid waste-based cementitious material or a completely solid waste cementitious material of the same grade.
[0014] Optionally, the steel slag content in the artificial reef concrete test block obtained in step S3 shall not be less than 55%; the artificial reef concrete test block shall maintain a compressive strength of more than 38 MPa after 28 days, a strength retention rate of not less than 95% after 360 days of seawater immersion, and a pH value that is stable at 8.39~8.46.
[0015] The present invention can achieve the following beneficial effects: 1) This invention breaks through the bottleneck of large-scale, high-value utilization of steel slag. Starting from the practical needs of large-scale steel slag production and low resource utilization, and considering the high demand and manufacturing cost of artificial reef concrete, this invention achieves full-scale utilization of steel slag through "direct stabilization of fine aggregates + core-shell granulation of coarse aggregates," with a steel slag content ≥55%. This not only enables large-scale, high-value utilization of steel slag but also meets the current high demand for artificial reefs, while significantly reducing the production cost of artificial reefs.
[0016] 2) This invention overcomes the shortcomings of steel slag stability, making it suitable for long-term marine service environments. Addressing the volume instability caused by free CaO (f-CaO) in steel slag, this invention employs a strategy of "direct stabilization of fine aggregate – preparation of coarse aggregate after grinding and stabilization – thermal curing of coarse aggregate" to improve aggregate stability and mechanical properties. Results show that the crushing value of the steel slag coarse aggregate is ≤5.6% (far lower than the requirement of ≤20% for crushed stone in C30 concrete), and the compressive strength retention rate of the concrete after 360 days of seawater immersion is ≥95%, solving the durability defects of existing technologies (such as CN105693168A, which does not consider long-term mechanical properties). Simultaneously, the pH of the artificial reef concrete test block remains stable between 8.2 and 8.4 after 360 days, close to the pH of natural seawater (8.1-8.3), avoiding the inhibition of biological growth by a highly alkaline environment (existing steel slag concrete often has a pH >9-10). Attached Figure Description
[0017] Figure 1 This is a flowchart of a method for preparing artificial reef concrete based on steel slag aggregate according to some embodiments of the present invention.
[0018] Figure 2 This is a flowchart illustrating the preparation of steel slag-based coarse aggregate in a method for preparing artificial reef concrete according to some embodiments of the present invention. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0020] In existing technologies, the resource utilization of steel slag faces serious challenges due to its poor stability. Relevant standards prohibit its use in cement production, and it has historically been barred from use as aggregate. Currently, the resource utilization rate of steel slag in my country is less than 20%, with over 1 billion tons of unused steel slag stockpiled. This massive accumulation of unused steel slag not only occupies land but also risks causing heavy metal pollution of soil and groundwater.
[0021] Therefore, the present invention provides a method for preparing artificial reef concrete based on steel slag aggregate treatment, the method comprising the following steps: S1: Preparation of steel slag fine aggregate Steel slag is crushed and screened to obtain granular materials with a particle size of less than or equal to 4.75 mm and greater than 4.75 mm. The steel slag particles with a particle size of less than or equal to 4.75 mm are subjected to stabilization pretreatment, and then dried and screened to obtain steel slag fine aggregate with a particle size distribution between 0.15 and 4.75 mm. S2: Preparation of steel slag-based coarse aggregate S21: Crushing and grinding steel slag particles with a particle size greater than 4.75 mm to obtain a specific surface area of 350~500 m². 2 Steel slag powder with a concentration between / kg was pretreated by water washing and then dried to obtain steel slag powder with good stability. S22: After mixing the steel slag powder obtained in S21 with the cementitious binder, put it into the disc granulation equipment, adjust the process parameters such as rotation speed and tilt angle, and spray water evenly into the disc granulation equipment at the same time. After completing the first granulation, it is screened to obtain particles with a certain particle size range for secondary granulation. S23: The one-step granulation product obtained in S22 that meets a certain particle size range is subjected to secondary granulation. The binder used in the secondary granulation is a mixture of cement and fly ash. The binder dosage is 30% to 50% of the mass of the one-step granulation product. The process parameters of the disc granulator are the same as those in step S22. After the secondary granulation is completed, coarse aggregate with an outer shell of pure binder is formed. S24: The particles obtained from the secondary granulation in step S4 are cured for the first time under certain temperature and humidity conditions, and then cured for the second time under another temperature and humidity conditions to obtain steel slag coarse aggregate with good stability and mechanical properties. S3: Preparation of Artificial Reef Concrete The steel slag fine aggregate and steel slag coarse aggregate obtained in S1 and S2 are mixed with cementitious materials in a certain proportion, and then water and admixtures are added. After mixing again, a uniform concrete mixture is obtained. Then, 150×150×150mm specimens are made in a mold and vibrated. After molding and demolding, the specimens are cured for 28 days in an environment with a temperature of 20±2℃ and a humidity of more than 95% to obtain artificial reef concrete specimens.
[0022] In one embodiment of the present invention, in step S1, the steel slag is steel slag with a metallic iron content of less than 2.0% obtained by pressure hot quenching process or pool hot quenching process and crushing and magnetic separation screening; the conditions for stabilizing the steel slag particles include: the treatment agent is acetic acid, oxalic acid, citric acid, ammonium chloride or water and a mixture thereof, the pH value is in the range of 3 to 7, the liquid-solid ratio is 1 to 10:1 (L / kg), the stabilization treatment time is 0.5 to 8 hours, the stirring speed is 20 to 100 r / min, and the number of treatments is based on the pH value of the last washing liquid being between 5 and 8.
[0023] In one embodiment of the present invention, the pretreatment conditions for washing the steel slag powder in step S21 include: a liquid-to-solid ratio of 1 to 10:1 (L / kg), a treatment time of 0.5 to 8 hours, a stirring speed of 20 to 100 r / min, and 2 to 5 washes.
[0024] In one embodiment of the present invention, in step S22, the mass ratio of steel slag powder to cementitious binder is 50~80:20~50, the cementitious binder is lime and fly ash with a mass ratio of 1:0.1~0.9, the one-step granulation disc granulation equipment has a disc diameter of 0.8m, a rotation speed of 35~55r / min, an inclination angle of 35°~55°, and a water spray volume of 20%~35% of the total mass of steel slag powder and cementitious binder, and the water spray is in the form of mist; after the one-step granulation is completed, particles with a diameter between 3~15mm are screened out for secondary granulation.
[0025] In one embodiment of the present invention, in step S23, the binder used in the secondary granulation is P·O42.5 cement with a mass ratio of fly ash of 1:1.
[0026] In one embodiment of the present invention, in step S24, the first curing temperature is 30~80℃, the relative humidity is above 95%, and the curing time is 10~20h; the second curing temperature is 18~22℃, the relative humidity is above 95%, and the curing time is 10~20 days.
[0027] In one embodiment of the present invention, in step S3, the mass ratio of the steel slag fine aggregate, steel slag coarse aggregate, cementitious material, water, and admixture is 20~35:44~55:20~35:4~17.5:0.02~0.14, wherein the admixture is a polycarboxylate superplasticizer, and the cementitious material is P·O42.5 cement or a solid waste-based cementitious material or a completely solid waste cementitious material of the same grade.
[0028] The results showed that the crushing value of steel slag coarse aggregate was ≤5.6% (far lower than the requirement of ≤20% for crushed stone in C30 concrete), and the compressive strength retention rate of the concrete after 360 days of seawater immersion was ≥95%, solving the durability defects of existing technologies (such as CN105693168A, which did not consider long-term mechanical properties). Meanwhile, the pH of the artificial reef concrete test blocks remained stable between 8.2 and 8.4 after 360 days, close to the pH of natural seawater (8.1-8.3), avoiding the inhibition of biological growth by a highly alkaline environment (the pH of existing steel slag concrete is often >9-10).
[0029] Example 1 The present invention provides a method for treating steel slag aggregate and a method for preparing artificial reef concrete based on the aggregate, the specific steps of which are as follows: S1: Preparation of fine aggregate from steel slag. Steel slag obtained from the pool-type hot quenching process is crushed, screened, and magnetically separated to obtain steel slag with a metallic iron content of 1.5%. The steel slag is then screened again to obtain particles with a diameter less than or equal to 4.75 mm and larger than 4.75 mm. The steel slag particles with a diameter less than or equal to 4.75 mm are then stabilized under the following conditions: acetic acid solution as the stabilizing agent, pH 4.0, liquid-to-solid ratio of 5:1 (L / kg), stabilization time of 2 hours, stirring speed of 50 r / min, and a washing liquid pH of 6 after two pretreatments. After liquid-solid separation, the solids are dried and screened to obtain well-stabilized fine aggregate from steel slag with a particle size distribution between 0.15 and 4.75 mm. S2: Preparation of steel slag-based coarse aggregate.
[0030] S21: The steel slag particles with a particle size greater than 4.75 mm obtained in S1 are crushed and ground to obtain a specific surface area of 350~500 m². 2 Steel slag powder with a volume between [value missing] and [value missing] kg was pretreated by water washing under the following conditions: liquid-to-solid ratio of 5:1 (L / kg), treatment time of 2 hours, stirring speed of 60 r / min, and three water washes. After liquid-solid separation, the solid was dried to obtain steel slag powder with good stability. S22: Mix the steel slag powder obtained in S21 with the cementitious binder at a mass ratio of 65:35, wherein the cementitious binder is lime and fly ash at a mass ratio of 1:0.5. Place the uniformly mixed steel slag powder and cementitious binder into a disc granulator with a diameter of 0.8m, adjust the rotation speed to 45r / min and the inclination angle to 45°, and spray water at 25% of the total mass of steel slag powder and cementitious binder in a mist form; after the first granulation is completed, screen out particles with a diameter between 3 and 15mm for secondary granulation.
[0031] S23: The one-step granulation product obtained in S22 is subjected to secondary granulation. The binder used in the secondary granulation is a mixture of P·O42.5 cement and fly ash with a mass ratio of 1:1. Its dosage is 40% of the mass of the one-step granulation product. The process parameters of the disc granulator are the same as those in step S22. After the secondary granulation is completed, coarse aggregate with an outer pure binder shell is formed. S24: The aggregate obtained in step S23 is cured at 50℃ and relative humidity above 95% for 15 hours as the first curing; then cured at 20℃ and relative humidity above 95% for 15 days as the second curing; after two curings, steel slag-based coarse aggregate with excellent mechanical properties is obtained. S3: Preparation of artificial reef concrete.
[0032] The stable steel slag fine aggregate and steel slag-based coarse aggregate obtained from S1 and S3 were mixed with P·O42.5 cement or solid waste-based cementitious material or all-solid waste cementitious material, water, and polycarboxylate superplasticizer in a mass ratio of 25:50:25:10:0.05 to obtain a homogeneous concrete mixture. Then, 150×150×150mm specimens were made in a mold and vibrated. After molding and demolding, the specimens were cured for 28 days in an environment with a temperature of 20℃ and a humidity of over 95% to obtain artificial reef concrete specimens.
[0033] Example 2 The present invention provides a steel slag aggregate treatment method and artificial reef concrete based on the aggregate, the specific steps of which are as follows: S1: Preparation of fine aggregate from steel slag. Steel slag obtained through a pressurized hot quenching process is crushed, screened, and magnetically separated to obtain steel slag with a metallic iron content of 1.5%. This steel slag is then screened to obtain particles with a diameter less than or equal to 4.75 mm and larger than 4.75 mm. The steel slag particles with a diameter less than or equal to 4.75 mm undergo stabilization treatment under the following conditions: ammonium chloride solution as the stabilizing agent, pH range of 4.5, liquid-to-solid ratio of 10:1 (L / kg), stabilization time of 1 hour, stirring speed of 30 r / min, and a washing liquid pH of 5.8 after three pretreatments. After liquid-solid separation, the solids are dried and screened to obtain well-stabilized fine aggregate from steel slag with a particle size distribution between 0.15 and 4.75 mm. S2: Preparation of steel slag-based coarse aggregate.
[0034] S21: The steel slag particles with a particle size greater than 4.75 mm obtained in S1 are crushed and ground to obtain a specific surface area of 350~500 m². 2 Steel slag powder with a volume between [value missing] and [value missing] kg was pretreated by water washing under the following conditions: liquid-to-solid ratio of 10:1 (L / kg), treatment time of 1 hour, stirring speed of 30 r / min, and three water washes. After liquid-solid separation, the solid was dried to obtain steel slag powder with good stability. S:22: Mix the steel slag powder obtained in S21 with the cementitious binder at a mass ratio of 60:40, wherein the cementitious binder is lime and fly ash at a mass ratio of 1:0.8. Place the uniformly mixed steel slag powder and cementitious binder into a disc granulator with a diameter of 0.8m, adjust the rotation speed to 40r / min, the inclination angle to 43°, and the water spray volume to 30% of the total mass of steel slag powder and cementitious binder, spraying water in a mist form; after the first granulation is completed, screen out particles with a diameter between 3 and 15mm for secondary granulation.
[0035] S23: The one-step granulation product obtained in S22 is subjected to secondary granulation. The binder used in the secondary granulation is a mixture of P·O42.5 cement and fly ash with a mass ratio of 1:1. Its dosage is 30% of the mass of the one-step granulation product. The process parameters of the disc granulator are the same as those in step S22. After the secondary granulation is completed, coarse aggregate with an outer pure binder shell is formed. S24: The aggregate obtained in step S23 is cured at 30℃ and relative humidity above 95% for 20 hours as the first curing; then cured at 20℃ and relative humidity above 95% for 20 days as the second curing; after two curings, steel slag-based coarse aggregate with excellent mechanical properties is obtained. S3: Preparation of artificial reef concrete.
[0036] The steel slag fine aggregate and steel slag-based coarse aggregate with good stability obtained from S1 and S3 were mixed with P·O42.5 cement or solid waste-based cementitious material or all-solid waste cementitious material, water and polycarboxylate superplasticizer in a mass ratio of 20:45:20:8:0.04 to obtain a uniform concrete mixture. Then, 150×150×150mm specimens were made in the mold and vibrated. After molding and demolding, the specimens were cured for 28 days in an environment with a temperature of 22℃ and a humidity of more than 95% to obtain artificial reef concrete specimens.
[0037] Example 3 The present invention provides a method for preparing steel slag aggregate and artificial reef concrete based on the aggregate, the specific steps of which are as follows: S1: Preparation of fine aggregate from steel slag.
[0038] Steel slag obtained from the pool-type hot quenching process was crushed, screened, and magnetically separated to obtain steel slag with a metallic iron content of 1.8%. The steel slag was then screened to obtain granular material with particle sizes less than or equal to 4.75 mm and greater than 4.75 mm. The steel slag particles with a particle size less than or equal to 4.75 mm underwent stabilization treatment under the following conditions: water as the stabilizing agent, pH range of 7.0, liquid-to-solid ratio of 10:1 (L / kg), stabilization time of 5 hours, stirring speed of 100 r / min, and the pH of the washing liquid after 8 pretreatments was 8. After liquid-solid separation, the solids were dried and screened to obtain well-stabilized steel slag fine aggregate with a particle size distribution between 0.15 and 4.75 mm. S2: Preparation of steel slag-based coarse aggregate.
[0039] S21: The steel slag particles with a particle size greater than 4.75 mm obtained in S1 are crushed and ground to obtain a specific surface area of 350~500 m². 2 Steel slag powder with a volume between [value missing] and [value missing] kg was pretreated by water washing under the following conditions: liquid-to-solid ratio of 10:1 (L / kg), treatment time of 5 hours, stirring speed of 100 r / min, and 5 washes. After liquid-solid separation, the solid was dried to obtain steel slag powder with good stability. S:2: Mix the steel slag powder obtained in S21 with the cementitious binder at a mass ratio of 70:30, wherein the cementitious binder is lime and fly ash at a mass ratio of 1:0.9. Place the uniformly mixed steel slag powder and cementitious binder into a disc granulator with a diameter of 0.8m, adjust the rotation speed to 50r / min, the inclination angle to 50°, and the water spray volume to 35% of the total mass of steel slag powder and cementitious binder, spraying water in a mist form; after the first granulation is completed, screen out particles with a diameter between 3 and 15mm for secondary granulation.
[0040] S23: The one-step granulation product obtained in S22 is subjected to secondary granulation. The binder used in the secondary granulation is a mixture of P·O42.5 cement and fly ash with a mass ratio of 1:1. Its dosage is 50% of the mass of the one-step granulation product. The process parameters of the disc granulator are the same as those in step S22. After the secondary granulation is completed, coarse aggregate with an outer pure binder shell is formed. S24: The aggregate obtained in step S23 is cured at 80℃ and relative humidity above 95% for 10 hours as the first curing; then cured at 22℃ and relative humidity above 95% for 20 days as the second curing; after two curings, steel slag-based coarse aggregate with excellent mechanical properties is obtained. S3: Preparation of artificial reef concrete.
[0041] The stable steel slag fine aggregate and steel slag-based coarse aggregate obtained from S1 and S2 were mixed with P·O42.5 cement or solid waste-based cementitious material or all-solid waste cementitious material, water, and polycarboxylate superplasticizer in a mass ratio of 30:55:35:14:0.1 to obtain a homogeneous concrete mixture. Then, 150×150×150mm specimens were made in a mold and vibrated. After molding and demolding, the specimens were cured for 28 days at a temperature of 18℃ and a humidity of over 95% to obtain artificial reef concrete specimens.
[0042] Comparative Example 1 The present invention provides Comparative Example 1, which is the same as Example 1 except that it does not perform steel slag fine aggregate stabilization treatment, grinding, washing, granulation, and curing. The specific steps are as follows: S1: Preparation of fine aggregate from steel slag.
[0043] The steel slag obtained from the pool-type hot quenching process is crushed, screened, and magnetically separated to obtain steel slag with a metallic iron content of 1.5%. This steel slag is then screened to obtain steel slag particles with particle sizes ranging from 0.15 to 4.75 mm and 4.75 to 20 μm. The steel slag particles between 0.15 and 4.75 mm are not subjected to stabilization treatment and are directly used as fine aggregate in artificial reef concrete.
[0044] S2: Preparation of steel slag-based coarse aggregate.
[0045] The steel slag particles between 4.75 and 20 mm obtained from the S1 sieve are not subjected to grinding, granulation, or curing treatment and are directly used as coarse aggregate for artificial reef concrete.
[0046] S3: Preparation of artificial reef concrete.
[0047] The steel slag fine aggregate and steel slag coarse aggregate obtained from S1 and S2 are mixed with P·O42.5 cement or solid waste-based cementitious material or all-solid waste cementitious material of the same grade, water, and polycarboxylate superplasticizer in a mass ratio of 25:50:25:10:0.05 to obtain a uniform concrete mixture. Then, 150×150×150mm specimens are made in a mold and vibrated. After molding and demolding, the specimens are cured for 28 days in an environment with a temperature of 20℃ and a humidity of over 95% to obtain artificial reef concrete specimens.
[0048] Comparative Example 2 The present invention provides Comparative Example 2, which is the same as Example 2 except that it does not involve the stabilization treatment of steel slag fine aggregate, grinding, washing, granulation, and curing. The specific steps are as follows: S1: Preparation of fine aggregate from steel slag.
[0049] Steel slag obtained from a pressurized hot quenching process is crushed, screened, and magnetically separated to obtain steel slag with a metallic iron content of 1.5%. This steel slag is then screened to obtain steel slag particles with particle sizes ranging from 0.15 to 4.75 mm and 4.75 to 20 μm. The steel slag particles between 0.15 and 4.75 mm are not subjected to stabilization treatment and are directly used as fine aggregate in artificial reef concrete.
[0050] S2: Preparation of steel slag-based coarse aggregate.
[0051] The steel slag particles between 4.75 and 20 mm obtained from the S1 sieve are not subjected to grinding, granulation, or curing treatment and are directly used as coarse aggregate for artificial reef concrete.
[0052] S3: Preparation of artificial reef concrete.
[0053] The steel slag fine aggregate and steel slag coarse aggregate obtained from S1 and S2 are mixed with P·O42.5 cement or solid waste-based cementitious material or all-solid waste cementitious material, water, and polycarboxylate superplasticizer in a mass ratio of 20:45:20:8:0.04 to obtain a homogeneous concrete mixture. Then, 150×150×150mm specimens are made in a mold and vibrated. After molding and demolding, the specimens are cured for 28 days at a temperature of 22℃ and a humidity of over 95% to obtain artificial reef concrete specimens.
[0054] Comparative Example 3 The present invention provides Comparative Example 3, which is the same as Example 3 except that it does not involve the stabilization treatment of steel slag fine aggregate, grinding, washing, granulation, and curing. The specific steps are as follows: S1: Preparation of fine aggregate from steel slag.
[0055] The steel slag obtained from the pool-type hot quenching process is crushed, screened, and magnetically separated to obtain steel slag with a metallic iron content of 1.8%. This steel slag is then screened to obtain steel slag particles with particle sizes ranging from 0.15 to 4.75 mm and 4.75 to 20 μm. The steel slag particles between 0.15 and 4.75 mm are not subjected to stabilization treatment and are directly used as fine aggregate in artificial reef concrete.
[0056] S2: Preparation of steel slag-based coarse aggregate.
[0057] The steel slag particles between 4.75 and 20 mm obtained from the S1 sieve are not subjected to grinding, granulation, or curing treatment and are directly used as coarse aggregate for artificial reef concrete.
[0058] S3: Preparation of artificial reef concrete.
[0059] The steel slag fine aggregate and steel slag coarse aggregate obtained from S1 and S3 were mixed with P·O42.5 cement or solid waste-based cementitious material or all-solid waste cementitious material, water, and polycarboxylate superplasticizer in a mass ratio of 30:55:35:14:0.1 to obtain a homogeneous concrete mixture. Then, 150×150×150mm specimens were made in a mold and vibrated. After molding and demolding, the specimens were cured for 28 days at a temperature of 18℃ and a humidity of over 95% to obtain artificial reef concrete specimens.
[0060] The physical properties of the coarse aggregates obtained in Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 1. It can be seen that after stabilization and granulation, the aggregate density is closer to that of natural crushed stone or pebbles (2.8-2.8 t / m³). 3 This reduces concrete weight, making it easier to transport and use; it also increases crushing value and water absorption by 44%-65%, which is beneficial to improving the mechanical properties of concrete.
[0061] The mechanical properties of the artificial reef concrete specimens obtained in Examples 1-3 and Comparative Examples 1-3, as well as the specimens after different periods of exposure to natural seawater, were tested. The results are shown in Table 2. The results indicate that, within different curing and seawater exposure periods, the compressive strength of the concrete specimens in Examples 1-3 was 40%-130% higher than that in Comparative Examples 1-3. Furthermore, the compressive strength retention rate of the concrete specimens in Examples 1-3 after 360 days in natural seawater exceeded 95%, far exceeding the relevant standard requirement of 20 MPa for the compressive strength of artificial reefs. In contrast, the compressive strength retention rate of the concrete specimens in Comparative Examples 1-3 after 360 days in natural seawater was only about 60%, and below 20 MPa.
[0062] The artificial reef concrete specimens obtained in Examples 1-3 and Comparative Examples 1-3 were placed in artificially prepared seawater (pH 8.2) at a volume ratio of 1:1 (artificial seawater to specimen volume), ensuring complete immersion of the specimens. The pH monitoring results at different times are shown in Table 3. The results indicate that the pH of the solution in Examples 1-3 was generally maintained between 8.39 and 8.46, close to the pH of the prepared seawater, which is conducive to the growth of marine organisms. In contrast, in Comparative Examples 1-3, the pH of the solution remained above 9.57 after 30 days, and showed a continuous increasing trend over time.
[0063] The results above show that this invention, through stabilization pretreatment of fine steel slag aggregate, grinding, washing, granulating, and curing coarse steel slag particles to prepare steel slag-based coarse aggregate, and then combining it with cementitious materials, water, and admixtures, produces artificial reef concrete specimens that exhibit good long-term mechanical properties and seawater compatibility. The steel slag content in this invention can reach 55%-70%, which not only solves the problem of large-scale, low-value utilization of steel slag but also reduces the cost of artificial reef concrete materials, demonstrating promising application prospects and economic benefits.
[0064] Table 1 Physical properties of coarse aggregate in comparative examples and embodiments Table 2. Compressive strength test results (MPa) at different times Table 3. pH test results at different times The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.
Claims
1. A method for preparing artificial reef concrete, characterized in that, The steps include the following: S1: Preparation of steel slag fine aggregate Steel slag is crushed and screened to obtain granular materials with a particle size of less than or equal to 4.75 mm and greater than 4.75 mm. The steel slag particles with a particle size of less than or equal to 4.75 mm are subjected to stabilization pretreatment, and then dried and screened to obtain steel slag fine aggregate with a particle size distribution between 0.15 and 4.75 mm. S2: Preparation of steel slag-based coarse aggregate S21: Crushing and grinding steel slag particles with a particle size greater than 4.75 mm to obtain a specific surface area of 350~500 m². 2 Steel slag powder with a concentration between / kg was pretreated by water washing and then dried to obtain steel slag powder with good stability. S22: After mixing the steel slag powder obtained in S21 with the cementitious binder, put it into the disc granulation equipment, adjust the process parameters of the disc granulation equipment, and spray water evenly into the disc granulation equipment at the same time. After completing the first step of granulation, it is screened to obtain particles that meet the preset particle size range. S23: The particles obtained in S22 that meet the preset particle size range are subjected to secondary granulation. The binder used for secondary granulation is a mixture of cement and fly ash. The binder dosage is 30% to 50% of the mass of the particles that meet the preset particle size range. The process parameters of the disc granulator are the same as those in step S22. After secondary granulation, coarse aggregate with an outer pure binder shell is formed. S24: The coarse aggregate particles obtained by secondary granulation in step S23 are cured for the first time under the first preset temperature and humidity conditions, and then cured for the second time under the second preset temperature and humidity conditions to obtain steel slag coarse aggregate with good stability and mechanical properties. S3: Preparation of artificial reef concrete The fine steel slag aggregate obtained in S1 and the coarse steel slag aggregate obtained in S2 are mixed with cementitious materials in a preset ratio, and then water and admixtures are added. After mixing again, a uniform concrete mixture is obtained. The mixture is then made into a test mold and vibrated. After molding and demolding, it is cured for 28 days in an environment with a temperature of 20±2℃ and a humidity of more than 95% to obtain artificial reef concrete test blocks.
2. The method for preparing artificial reef concrete according to claim 1, characterized in that, Before crushing and screening the steel slag in step S1, the method further includes: The steel slag is subjected to pressurized hot quenching or pool-type hot quenching process, and then magnetically separated to obtain steel slag with a metallic iron content of less than 2.0%.
3. The method for preparing artificial reef concrete according to claim 1, characterized in that, The stabilization pretreatment conditions for the steel slag particles in step S1 are as follows: The treatment agent used is at least one of acetic acid, oxalic acid, citric acid, ammonium chloride, or water. The pH value of the treatment agent is in the range of 3 to 7. The liquid-solid ratio of the treatment agent to the steel slag particles is 1 to 10 L: 1 kg. The stabilization treatment time is 0.5 to 8 h. The stirring speed is 20 to 100 r / min. The number of treatments is based on the pH value of the last washing solution being between 5 and 8.
4. The method for preparing artificial reef concrete according to claim 1, characterized in that, The pretreatment conditions for water washing of steel slag powder in step S21 are as follows: The liquid-to-solid ratio of water to steel slag powder is 1~10L:1kg, the treatment time is 0.5~8h, the stirring speed is 20~100r / min, and the number of water washes is 2~5 times.
5. The method for preparing artificial reef concrete according to claim 1, characterized in that, In step S22, the mass ratio of steel slag powder to cementitious binder is 50~80:20~50, and the cementitious binder is lime and fly ash, with a mass ratio of lime to fly ash of 1:0.1~0.
9. The process parameters for adjusting the disc granulation equipment include: setting the particle diameter to about 0.8m, the rotation speed to 35~55r / min, the tilt angle to 35°~55°, and the water spray volume to 20%~35% of the total mass of steel slag powder and cementitious binder, with the water sprayed in a mist form; After the first granulation is completed, particles with a diameter between 3 and 15 mm are screened out for secondary granulation.
6. The method for preparing artificial reef concrete according to any one of claims 1-6, characterized in that, In step S23, the cement used in the secondary granulation binder is P·O42.5 cement, and the mass ratio of P·O42.5 cement to fly ash in the binder is 1:
1.
7. The method for preparing artificial reef concrete according to any one of claims 1-6, characterized in that, The first preset temperature and humidity conditions in step S24 include: temperature of 30~80℃, relative humidity of 95% or higher, and curing time of 10~20h; The second preset temperature and humidity conditions include: temperature of 18~22℃, relative humidity of 95% or higher, and curing time of 10~20 days.
8. The method for preparing artificial reef concrete according to any one of claims 1-6, characterized in that, In step S3, the mass ratio of fine steel slag aggregate, coarse steel slag aggregate, cementitious material, water, and admixture is 20~35:44~55:20~35:4~17.5:0.02~0.
14. The admixture is a polycarboxylate superplasticizer, and the cementitious material is P·O42.5 cement or a solid waste-based cementitious material or a completely solid waste cementitious material of the same grade.
9. The method for preparing artificial reef concrete according to any one of claims 1-6, characterized in that, The steel slag content in the artificial reef concrete test block obtained in step S3 shall not be less than 55%; the artificial reef concrete test block shall maintain a compressive strength of more than 38 MPa after 28 days of intactness, a strength retention rate of not less than 95% after 360 days of seawater immersion, and a pH value that is stable at 8.39~8.46.