A kind of steel slag powder-based concrete and preparation method thereof

Abstract

The present invention discloses a steel slag powder-based concrete and a preparation method thereof, belonging to the technical field of concrete materials. The cementitious material prepared by the present invention using cement, steel slag powder, slag powder and silica fume can effectively cooperate with PE fibers. At the same time, calcium sulfate whiskers can also promote each other with PE fibers, enhance the toughness of steel slag powder-based concrete, and improve the stability of steel slag powder-based concrete at high temperatures. The steel slag is mechanically ground to obtain a specific surface area greater than 450 m 2 / kg of steel slag powder is modified and then added as an admixture to cement binder to produce ultra-high ductility concrete. When polyethylene fiber is added, the cement-based composite binder can better cooperate with each other, and the steel slag powder ultra-high ductility concrete can show more excellent mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of concrete materials, and in particular to steel slag powder-based concrete and a preparation method thereof. Background Art

[0002] Steel slag is a byproduct formed by the reaction of steelmaking raw materials with various fluxes and slag-forming materials during the smelting process. Generally, 120~210 kg of steel slag is produced for every ton of steel produced. The large amount of steel slag produced has become a large solid waste. Generally, the content of minerals with high hydration activity in steel slag is low, but the content of free calcium oxide and free magnesium oxide is high. After the hydration reaction, Ca(OH)2 and Mg(OH)2 are easily generated, affecting the volume stability. Due to the complex composition of steel slag, large fluctuations in content, and rich in heavy metals, these factors limit the resource utilization of steel slag, making the comprehensive utilization of steel slag difficult. The application of steel slag in the concrete industry is a feasible way to comprehensively utilize steel slag.

[0003] Theoretically, the microscopic morphology of steel slag powder particles is less angular and flaky, which helps disperse the fibers and enhances the interfacial bonding between the fibers and the matrix. At the same time, the modification of steel slag powder improves the initial activity and stability, making it more suitable as an admixture for concrete, thereby promoting the comprehensive utilization of steel slag powder, reducing environmental burden, and improving the performance and durability of concrete. Su Jun et al. published an article entitled "Study on the Tensile Properties of Ultra-High Toughness Cement-Based Materials Blended with Steel Slag Powder" in the Journal of Hubei University of Technology. This existing technology prepares ultra-high toughness cement-based composite materials by blending steel slag powder. The results show that it is feasible to prepare cement-based composite materials using steel slag powder, but the ductility of PVA fibers is poor and cannot achieve a higher elongation fracture capacity. Wu Peng et al. published a paper titled "Bending Performance Test of Cement-based Composite Material Reinforced with High Toughness Fiber Added with Steel Slag Powder" in "Concrete". This prior art focuses on improving the utilization rate of steel slag, and improves the performance of cement-based materials with large amounts of steel slag powder by adding polyvinyl alcohol fibers to them, and prepares cement-based composite materials with ultra-high toughness with large amounts of steel slag powder. The basic mechanical properties and crack control ability are studied by compressive strength test and thin plate three-point bending test. However, the dispersion of polyvinyl alcohol fibers in concrete is poor, and the fibers are short, which limits the fiber reinforcement effect and affects the crack resistance of concrete. At the same time, the price is high, which increases the cost of concrete. The publication number is CN114620970A: Steel Slag Powder Concrete and Its Preparation Method and Application, which discloses a kind of economical, green steel slag powder concrete with good fluidity, gap passability and anti-segregation. The concrete prepared by the steel slag powder concrete has compressive strength that meets the standard and greatly reduces the production cost. The steel slag powder concrete focuses on compressive strength, has high brittleness, fails to improve the tensile strength, toughness and fatigue resistance of concrete, and fails to improve the high temperature resistance of concrete. To this end, the present invention provides a steel slag powder-based concrete and a preparation method thereof. Summary of the invention

[0004] The present invention provides a steel slag powder-based concrete and a preparation method thereof, which effectively solves the problems of low steel slag powder activity, poor stability and metal pollution in the existing steel slag powder-based concrete, and provides a steel slag powder-based concrete with better toughness, high temperature resistance and excellent high temperature mechanical properties.

[0005] The first object of the present invention is to provide a steel slag powder-based concrete, characterized in that it is composed of the following raw materials in parts by weight: 400-450 parts of cement, 300-350 parts of modified steel slag powder, 150-180 parts of slag powder, 190-205 parts of silica fume, 3-5 parts of calcium sulfate whiskers, 8-20 parts of polyethylene fibers, 260-280 parts of water, 2-4 parts of water reducer and 1-2 parts of thickener.

[0006] As a preferred embodiment, the preparation method of the modified steel slag powder is specifically as follows: grinding and sieving the steel slag powder, adding 4% to 6% potassium methyl silicate solution by mass of the steel slag powder, wherein the mass concentration of the potassium methyl silicate solution is 80%, stirring, and drying to obtain the modified steel slag powder.

[0007] As a preferred embodiment, the modified steel slag powder has a specific surface area greater than 450 m 2 / kg, 7-day activity index ≥50%, 28-day activity index ≥65%.

[0008] As a preferred implementation, after grinding and screening, the particle size of the steel slag powder is 0.15 μm to 0.6 μm.

[0009] As a preferred embodiment, the calcium sulfate whisker has a diameter of 1 μm to 8 μm, a length of 30 μm to 200 μm, an aspect ratio of 10 to 200, a CaSO4 content of ≥ 98%, a melting point of 1450°C, a water solubility of < 1200 ppm, and a density of 2.69 g / cm 3 , tensile strength is 20.5GPa, tensile modulus is 178GPa, and pH value is 6~8.

[0010] As a preferred embodiment, the silicon dioxide content in the slag powder is greater than 90%; the silica fume is primary silica fume, with a specific surface area of ​​≥400m² / kg and a particle size range of 25μm to 100μm; the cement is ordinary Portland cement, with an initial setting time of >45min, a final setting time of <10h, and a 28d strength of ≥42.5MPa.

[0011] As a preferred embodiment, the polyethylene fiber has a length of 10 mm to 30 mm, a diameter of 15 μm to 25 μm, an aspect ratio of ≥500, an elongation at break of 3% to 4%, an elastic modulus of ≥110 GPa, and a tensile strength of ≥2800 MPa.

[0012] The second object of the present invention is to provide a method for preparing the above-mentioned steel slag powder-based concrete, comprising the following steps:

[0013] Weigh the following raw materials in parts by weight: 400-450 parts of cement, 300-350 parts of modified steel slag powder, 150-180 parts of slag powder, 190-205 parts of silica fume, 3-5 parts of calcium sulfate whiskers, 8-20 parts of polyethylene fiber, 260-280 parts of water, 2-4 parts of water reducer and 1-2 parts of thickener;

[0014] Cement, silica fume, slag powder, modified steel slag powder and part of water reducing agent are dry-mixed and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducing agent is added and stirred; a thickener is added and stirred; polyethylene fiber is added and stirred at 105 r / min to 125 r / min and then at 185 r / min to 205 r / min; the fiber is evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0015] As a preferred embodiment, the weight of the partial water reducing agent is 50% of the weight of the water reducing agent.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention provides a steel slag powder-based concrete and a preparation method thereof. When preparing high-ductility steel slag powder-based concrete, the cementitious material made of cement, steel slag powder, slag powder and silica fume can effectively cooperate with PE fiber. At the same time, calcium sulfate whiskers can also promote each other with PE fiber, enhance the toughness of steel slag powder-based concrete, and improve the stability of steel slag powder-based concrete at high temperature. The steel slag is mechanically ground to obtain a specific surface area greater than 450m 2 / kg of steel slag powder is modified and added to cement binder as an admixture to produce ultra-high ductility concrete. When polyethylene fiber is added, the cement-based composite binder can work better together, and the steel slag powder ultra-high ductility concrete can show more excellent mechanical properties. By reasonably improving and treating the activity and stability of steel slag powder and reducing heavy metal pollution, it can not only save energy consumption, but also reduce environmental pollution, so it can be used to prepare green concrete.

[0018] 2. The present invention can convert Ca(OH)2, CaCO3 and free calcium oxide in steel slag powder into calcium formate products through chemical modification, but the active silicate therein is not significantly affected, thereby improving the initial activity and stability. The modified steel slag powder can be used as an admixture in concrete to improve the interfacial bonding of the cement matrix. In addition, slag powder and silica fume can improve the compactness of the fiber matrix-interface, promote the affinity between the interfaces, and make the concrete hydration structure more complete. The bridging synergistic effect between the composite cement paste and the fiber has correspondingly improved the mechanical properties and working performance of the concrete.

[0019] 3. The present invention uses calcium sulfate whiskers to toughen steel slag powder-based concrete. Calcium sulfate whiskers perform well in high temperature environments and can maintain stability under extreme temperature conditions. The temperature they can withstand can reach several thousand degrees Celsius. They have good oxidation resistance in high temperature environments and can remain relatively stable in oxidizing atmospheres and are not easily oxidized or corroded. At the same time, calcium sulfate whiskers have excellent mechanical properties, including high strength and high hardness. This enables them to provide excellent tensile, bending and compressive resistance. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific examples, but the examples are not intended to limit the present invention. The following test methods and detection methods, unless otherwise specified, are conventional methods; the reagents and raw materials, unless otherwise specified, are commercially available.

[0021] In view of the above mentioned in the background technology of the present invention: First, in the prior art, when steel slag powder is used to prepare ultra-high toughness cement-based composite materials, the PVA fiber has poor ductility and cannot reach a higher extension fracture capacity; second, when preparing high-toughness fiber-reinforced cement-based composite materials with steel slag powder, polyvinyl alcohol fiber is added to the cement-based material with a large amount of steel slag powder to improve its performance, and the basic mechanical properties and crack control ability are studied by compressive strength test and thin plate three-point bending test. Due to the poor dispersion performance of polyvinyl alcohol fiber in concrete and the short fiber, the fiber reinforcement effect is limited, the crack resistance of concrete is affected, and the price is high, which increases the cost of concrete; third, the existing steel slag powder concrete focuses on compressive strength, has high brittleness, fails to improve the tensile strength, toughness and fatigue resistance of concrete, and fails to improve the high temperature resistance of concrete. It can be seen that the existing steel slag powder-based concrete has the problems of low activity, poor stability and metal pollution of steel slag powder. Based on the above technical problems, the present invention provides a steel slag powder-based concrete and a preparation method thereof, and the technical scheme of the present invention is analyzed and explained in detail below.

[0022] The present invention first provides a steel slag powder-based concrete, which is composed of the following raw materials in parts by weight: 400-450 parts of cement, 300-350 parts of modified steel slag powder, 150-180 parts of slag powder, 190-205 parts of silica fume, 3-5 parts of calcium sulfate whiskers, 8-20 parts of polyethylene fiber, 260-280 parts of water, 2-4 parts of water reducer and 1-2 parts of thickener, wherein the thickener is hydroxypropyl methylcellulose. When preparing high-ductility steel slag powder concrete, the cementitious material prepared by cement, steel slag powder, slag powder and silica fume can effectively cooperate with PE fiber. At the same time, the calcium sulfate whiskers can also promote each other with the PE fiber, enhance the toughness of the steel slag powder-based concrete, and improve the stability at high temperature.

[0023] It should be emphasized that the use of the ternary composite cementitious material of steel slag powder-slag powder-silica fume in the present invention can reduce carbon emissions compared with traditional cement, achieve the effect, and realize the efficient connection between the composite cementitious material and the polyethylene fiber. The prepared modified steel slag powder ultra-high ductility concrete has good particle grading and flow properties. It has a better synergistic effect with slag and silica fume, and improves the microscopic and macroscopic properties between steel slag powder, slag powder and silica fume. This new type of concrete is easier to prepare, based on the design of bulk density and matrix fracture toughness, the regulation of fiber-matrix interface bonding properties, and the application of micromechanical models. By adjusting the raw materials and proportions, a high-temperature resistant, environmentally friendly, and excellent mechanical properties of steel slag powder ultra-high ductility concrete with microcracks and cracks was successfully prepared, realizing the resource utilization of solid waste steel slag powder and slag powder.

[0024] In order to further improve the synergistic effect between the steel slag powder and the other components in the concrete, the preparation method of the modified steel slag powder is as follows: grind and sieve the steel slag powder to a particle size of 0.15 μm to 0.6 μm, add 4% to 6% of the mass of the steel slag powder and a mass concentration of 80% potassium methyl silicate solution, stir, and dry to obtain the modified steel slag powder. The specific surface area of ​​the modified steel slag powder is greater than 450 m 2 / kg, 7d activity index ≥50%, 28d activity index ≥65%. The steel slag is mechanically ground to obtain a specific surface area greater than 450m 2 / kg of steel slag powder is modified and added to cement binder as an admixture to produce ultra-high ductility concrete. The Ca(OH)2, CaCO3 and free calcium oxide in the steel slag powder can be converted into calcium formate products through chemical modification, but the active silicates in it are not significantly affected, thereby improving the early activity and stability. The modified steel slag powder can be used as an admixture in concrete to improve the interfacial bonding degree of the modified steel slag powder matrix. In addition, slag powder and silica fume can improve the density of the fiber matrix-interface, promote the affinity between the interfaces, improve the interfacial bonding strength, and make the concrete hydration structure more complete. The modified steel slag powder is combined with the binder prepared by alkali activation of silica fume and slag powder. In this process, Ca(OH)2 in the steel slag powder can participate in the reaction and generate calcium silicate, while the active silicates in the steel slag powder are not affected, thereby improving the early activity of the steel slag powder. The modified product calcium formate has hydration activity, and the hydration heat is increased by 1 to 4 times. The bridging synergistic effect between the composite cement paste and the fiber has improved the mechanical properties and working performance of the concrete accordingly. When an appropriate amount of polyethylene fiber is added, the cement-based composite cementitious materials can work better together, and the steel slag powder ultra-high ductility concrete can show more excellent mechanical properties. By reasonably improving and treating the activity and stability of steel slag powder and reducing heavy metal pollution, it can not only save energy consumption, but also reduce environmental pollution and be used to prepare green concrete.

[0025] It should be noted that silica fume and silicate hydration products make the concrete structure more compact and complete, and the strength is significantly improved. In the ternary cementitious system of steel slag powder-slag powder-silicon fume of the present invention, the slag powder has a higher hydration reaction in the whole stage, which improves the overall hydration reaction. The participation of silica fume makes the surface of steel slag powder and slag powder uniformly adsorb a layer of silica fume, effectively consumes CH in the reaction system, and enhances the connection between steel slag powder-slag powder and the surrounding CSH gel.

[0026] In order to further improve the mechanical properties of steel slag powder-based concrete, after grinding and screening, the particle size of the steel slag powder is 0.15 μm to 0.6 μm, and the specific surface area of ​​the modified steel slag powder is greater than 450 m 2 / kg, 7d activity index ≥50%, 28d activity index ≥65%. The steel slag powder is prepared by putting the cooled steel slag into a jaw crusher and a roller press for crushing. The crushed steel slag is sorted into magnetic slag and non-magnetic slag by a magnetic separator. The non-magnetic slag is selected and screened to reach a certain particle size and then enters a vertical grinding mill for full grinding to make steel slag powder. After such a process treatment, the metallic iron in the steel slag can be effectively recycled, and the steel slag powder with reduced iron content has higher hydration activity and better stability, and is more suitable for preparing synthetic cement. The early activity of the modified steel slag powder is well improved, which can improve the compressive strength and flexural strength of concrete, promote the formation of cement gel, and thus enhance the mechanical properties. In addition, the modified steel slag powder has good density and chemical stability, can reduce the porosity in concrete, and improve the durability of concrete.

[0027] In order to further improve the toughness and mechanical properties of steel slag powder-based concrete, the diameter of the calcium sulfate whisker is 1μm-8μm, the length is 30μm-200μm, the aspect ratio is 10-200, the CaSO4 content is ≥98%, the melting point is 1450℃, the water solubility is <1200ppm, and the density is 2.69g / cm 3 , tensile strength of 20.5GPa, tensile modulus of 178GPa, and pH value of 6-8. The present invention toughens steel slag powder-based concrete through calcium sulfate whiskers. Calcium sulfate whiskers perform well in high temperature environments and can maintain stability under extreme temperature conditions. The temperature they withstand can reach several thousand degrees Celsius. It has good oxidation resistance in high temperature environments, can remain relatively stable in an oxidizing atmosphere, and is not easily oxidized or corroded. At the same time, calcium sulfate whiskers have excellent mechanical properties, including high strength and high hardness. This enables it to provide excellent tensile, bending and compressive resistance.

[0028] It should be noted that calcium sulfate whiskers are a fibrous material with a series of excellent physical properties, which make them widely used in high temperature and high strength environments. Calcium sulfate whiskers perform well in high temperature environments and can maintain stability under extreme temperature conditions. Its operating temperature range can usually reach several thousand degrees Celsius. At the same time, it has excellent mechanical properties, including high strength and high hardness. This enables it to provide excellent tensile, bending and compressive resistance in some demanding applications. In addition, calcium sulfate whiskers have good oxidation resistance in high temperature environments, can remain relatively stable in oxidizing atmospheres, and are not easily oxidized or corroded. Calcium sulfate is an excellent thermal conductive material, and calcium sulfate whiskers, as its derivatives, also have high thermal conductivity, making them suitable for some applications with high thermal conductivity requirements. Calcium sulfate whiskers are relatively stable chemically and have good corrosion resistance. When preparing calcium sulfate whiskers using semi-aqueous desulfurized gypsum as raw material, the raw materials do not need to be pretreated. The optimal preparation process is slurry concentration of 5%, solution pH = 5, sodium dodecyl sulfate dosage of 2%, reaction temperature of 140 ° C, and reaction time of 2.5h. Under this process, calcium sulfate whisker products with an average diameter of 1μm to 2μm and an average aspect ratio of up to 100 are prepared, with excellent morphology and uniform distribution.

[0029] In order to further improve the bonding strength between slag powder, silica fume and cement and other components in concrete, the silica content in the slag powder is greater than 90%; the silica fume is first-grade silica fume, with a specific surface area of ​​≥400m² / kg and a particle size range of 25μm to 100μm; the cement is ordinary Portland cement, with an initial setting time of >45min, a final setting time of <10h, and a 28d strength of ≥42.5MPa. The addition of silica fume makes the steel slag powder ultra-high ductility concrete of the present invention have better fluidity, increase the density between concrete, reduce the formation of pores and cracks, and reduce the viscosity and internal friction of cement concrete, so that the mechanical and thermal properties of concrete are improved, and the early and late strength of a high temperature resistant concrete is improved.

[0030] Furthermore, the slag powder has a specific surface area of ​​432m 2 / kg, water content 0.26%. The active silicates in slag powder react with modified steel slag powder and silica fume to form cementitious substances, which enhance the strength and durability of concrete. Adding slag powder can fill the pores in concrete, promote the formation of cementitious substances, improve the density of concrete, and thus improve the compressive strength, tensile strength and flexural strength of concrete. At the same time, the active ingredients in slag powder can reduce the penetration of chloride ions in concrete and improve the ability to resist chloride ion erosion. In addition, the mineral components in slag powder can also improve the concrete's resistance to sulfate erosion and alkali-aggregate reaction, and extend the service life of concrete. The application of slag powder can reduce the exploitation of natural resources, reduce environmental pollution and energy consumption. Slag is a by-product of the metallurgical industry. Using it as an admixture for concrete materials can effectively utilize resources and reduce the generation of solid waste. The application of slag powder can improve the fluidity and plasticity of concrete and improve its construction performance. Adding an appropriate amount of slag powder can reduce the viscosity of concrete, increase fluidity, and make it easier to construct and shape.

[0031] In order to increase the interface connection strength between the polyethylene fiber and the remaining components, the polyethylene fiber is 10mm to 30mm in length, 15μm to 25μm in diameter, has an aspect ratio of ≥500, an elongation at break of 3% to 4%, an elastic modulus of ≥110GPa, and a tensile strength of ≥2800MPa. The present invention adopts polyethylene fiber to prepare a high-temperature resistant steel slag powder ultra-high ductility concrete. Through the interface connection between the PE fiber and the matrix, the crack expansion of the concrete can be effectively prevented, and the crack resistance of the concrete can be improved. Especially in the case of shrinkage and temperature changes, the toughness and impact resistance of the concrete can also be increased, and its durability can be improved. The addition of polyethylene fiber can reduce the cracking and crushing of concrete, and delay the aging and damage of concrete. Polyethylene fiber can fill the pores in concrete and improve its density, and the addition of fiber can reduce the pores and microcracks in concrete, improve the impermeability of concrete, and prevent water penetration. Improve the fluidity of concrete and improve its construction performance. At the same time, the addition of fiber can reduce the viscosity and internal friction of concrete, making it easier to pour, vibrate and smooth. Polyethylene fiber can increase the wear resistance of concrete and extend the service life of concrete. The addition of fiber can reduce the wear and tear of the concrete surface and improve its wear resistance. It enables the steel slag powder-based ultra-high ductility concrete to better meet the strength criteria and energy criteria.

[0032] It should be noted that the water reducer is a composite functional polycarboxylate water reducer. The water reducer is prepared by aqueous solution free radical polymerization with modified polyether isopentenol polyoxyethylene ether as a functional macromonomer, methacryloyloxyethyl trimethylammonium chloride, acrylic acid and maleic anhydride as functional minor monomers, hydrogen peroxide and ascorbic acid redox system as initiators, and mercaptopropionic acid as a chain transfer agent. A composite functional polycarboxylate water reducer with anti-mud and collapse-preserving properties is superior to ordinary water reducers on the market.

[0033] The technical effects of the technical solution of the present invention are described below in conjunction with specific embodiments and comparative examples.

[0034] The steel slag powder-based concrete of the present invention is mainly made of silica fume, steel slag powder and slag powder, a polycarboxylic acid high-efficiency water-reducing agent is selected as a water reducer, hydroxypropyl methyl cellulose ether is selected as a thickener, and calcium sulfate whisker is selected as a high-temperature resistant material;

[0035] Example 1

[0036] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 425 parts of cement, 326 parts of modified steel slag powder, 178 parts of slag powder, 195 parts of silica fume, 4 parts of calcium sulfate whiskers, 14 parts of polyethylene fibers, 278 parts of water, 3 parts of water reducing agent and 1 part of thickener.

[0037] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 5 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0038] Dry-mix cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducer for 1 minute, and mix them evenly to obtain a cementitious material; add water and calcium sulfate whiskers to the cementitious material and mix well; then add the remaining water reducer and stir at 105 r / min for 1 minute; add a thickener and stir at 105 r / min for 1 minute; then add polyethylene fiber and stir at 105 r / min for 1 minute and then stir at 185 r / min for 2 minutes; disperse the fiber evenly in the cementitious material to obtain steel slag powder-based concrete.

[0039] After testing, the specimen had a tensile strength of 5.35 MPa, a tensile strain capacity of 8.92%, 57 cracks, and a crack width of 125 μm, showing good steady-state cracking behavior and deformation capacity.

[0040] Example 2

[0041] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 435 parts of cement, 320 parts of modified steel slag powder, 155 parts of slag powder, 205 parts of silica fume, 5 parts of calcium sulfate whiskers, 15 parts of polyethylene fibers, 270 parts of water, 3 parts of water reducing agent and 1 part of thickener.

[0042] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 10 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0043] Cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducing agent are dry-mixed for 2 minutes, and the mixture is evenly mixed to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducing agent is added and stirred at 125 r / min for 2 minutes; a thickener is added and stirred at 125 r / min for 2 minutes; polyethylene fibers are added and stirred at 125 r / min for 2 minutes and then at 205 r / min for 4 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0044] After testing, the specimen had a tensile strength of 6.08 MPa, a tensile strain capacity of 9.85%, 60 cracks, and a crack width of 131 μm, showing good steady-state cracking behavior and deformation capacity.

[0045] Example 3

[0046] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 405 parts of cement, 305 parts of modified steel slag powder, 175 parts of slag powder, 190 parts of silica fume, 3 parts of calcium sulfate whiskers, 12 parts of polyethylene fibers, 268 parts of water, 3 parts of water reducing agent and 1 part of thickener.

[0047] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 8 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0048] Silica fume, slag powder, modified steel slag powder and half the weight of water reducer are dry-mixed for 3 minutes and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; then the remaining water reducer is added and stirred at 110 r / min for 1 minute; a thickener is added and stirred at 110 r / min for 1 minute; then polyethylene fibers are added and stirred at 110 r / min for 1 minute and then at 185 r / min for 4 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0049] After testing, the specimen had a tensile strength of 5.98 MPa, a tensile strain capacity of 10.26%, 68 cracks, and a crack width of 120 μm, showing good steady-state cracking behavior and deformation capacity.

[0050] Example 4

[0051] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 400 parts of cement, 350 parts of modified steel slag powder, 150 parts of slag powder, 190 parts of silica fume, 3 parts of calcium sulfate whiskers, 8 parts of polyethylene fibers, 280 parts of water, 2 parts of water reducing agent and 1 part of thickener.

[0052] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 4% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 6 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0053] Cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducing agent are dry-mixed for 2 minutes, and the mixture is evenly mixed to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducing agent is added and stirred at 120 r / min for 2 minutes; a thickener is added and stirred at 120 r / min for 2 minutes; polyethylene fibers are added and stirred at 120 r / min for 2 minutes and then at 205 r / min for 2 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0054] After testing, the tensile strength of the specimen was 5.62MPa, the tensile strain capacity was 9.05%, the number of cracks was 58, the crack width was 123μm, and it had good steady-state cracking behavior and deformation capacity.

[0055] Example 5

[0056] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 450 parts of cement, 300 parts of modified steel slag powder, 180 parts of slag powder, 205 parts of silica fume, 5 parts of calcium sulfate whiskers, 20 parts of polyethylene fibers, 260 parts of water, 4 parts of water reducing agent and 2 parts of thickener.

[0057] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 6% by mass of the steel slag powder, and the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 7 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0058] Cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducer are dry-mixed for 3 minutes and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducer is added and stirred at 115 r / min for 2 minutes; a thickener is added and stirred at 115 r / min for 2 minutes; polyethylene fibers are added and stirred at 115 r / min for 2 minutes and then at 200 r / min for 3 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0059] After testing, the tensile strength of the specimen was 5.71MPa, the tensile strain capacity was 9.31%, the number of cracks was 59, the crack width was 128μm, and it had good steady-state cracking behavior and deformation capacity.

[0060] Example 6

[0061] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 410 parts of cement, 330 parts of modified steel slag powder, 160 parts of slag powder, 200 parts of silica fume, 4 parts of calcium sulfate whiskers, 10 parts of polyethylene fibers, 265 parts of water, 4 parts of water reducing agent and 2 parts of thickener.

[0062] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 9 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0063] Cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducer are dry-mixed for 1 minute and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducer is added and stirred at 120 r / min for 1 minute; a thickener is added and stirred at 120 r / min for 1 minute; polyethylene fibers are added and stirred at 120 r / min for 1 minute and then at 200 r / min for 2 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0064] After testing, the specimen had a tensile strength of 6.00 MPa, a tensile strain capacity of 9.25%, 57 cracks, and a crack width of 126 μm, showing good steady-state cracking behavior and deformation capacity.

[0065] Example 7

[0066] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 420 parts of cement, 320 parts of modified steel slag powder, 170 parts of slag powder, 198 parts of silica fume, 5 parts of calcium sulfate whiskers, 16 parts of polyethylene fibers, 275 parts of water, 2 parts of water reducing agent and 1 part of thickener.

[0067] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 10 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0068] Cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducing agent are dry-mixed for 2 minutes and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; then the remaining water reducing agent is added and stirred at 125 r / min for 1 minute; a thickener is added and stirred at 125 r / min for 1 minute; then polyethylene fibers are added and stirred at 125 r / min for 1 minute and then at 200 r / min for 4 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0069] After testing, the specimen had a tensile strength of 5.49 MPa, a tensile strain capacity of 8.80%, 55 cracks, and a crack width of 119 μm, showing good steady-state cracking behavior and deformation capacity.

[0070] Example 8

[0071] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 430 parts of cement, 340 parts of modified steel slag powder, 165 parts of slag powder, 202 parts of silica fume, 3 parts of calcium sulfate whiskers, 18 parts of polyethylene fibers, 280 parts of water, 3 parts of water reducing agent and 2 parts of thickener.

[0072] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 5 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0073] Cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducing agent are dry-mixed for 3 minutes and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducing agent is added and stirred at 105 r / min for 2 minutes; a thickener is added and stirred at 105 r / min for 2 minutes; polyethylene fibers are added and stirred at 105 r / min for 2 minutes and then at 190 r / min for 2 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0074] After testing, the specimen had a tensile strength of 5.78 MPa, a tensile strain capacity of 9.54%, 56 cracks, and a crack width of 124 μm, showing good steady-state cracking behavior and deformation capacity.

[0075] In order to further illustrate the technical effect of the present invention, the present invention also sets a comparative example, which is as follows:

[0076] Comparative Example 1

[0077] Compared with Example 1, the difference is that the weight portion of the polyethylene fiber is reduced to 1 part.

[0078] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 425 parts of cement, 326 parts of modified steel slag powder, 178 parts of slag powder, 195 parts of silica fume, 4 parts of calcium sulfate whiskers, 1 part of polyethylene fiber, 278 parts of water, 3 parts of water reducing agent and 1 part of thickener.

[0079] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 5 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0080] Dry-mix cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducer for 1 minute, and mix them evenly to obtain a cementitious material; add water and calcium sulfate whiskers to the cementitious material and mix well; then add the remaining water reducer and stir at 105 r / min for 1 minute; add a thickener and stir at 105 r / min for 1 minute; then add polyethylene fiber and stir at 105 r / min for 1 minute and then stir at 185 r / min for 2 minutes; disperse the fiber evenly in the cementitious material to obtain steel slag powder-based concrete.

[0081] After testing, the tensile strength of the specimen was 3.56MPa and the specimen suffered brittle failure.

[0082] Comparative Example 2

[0083] Compared with Example 1, the difference is that the weight proportion of the polyethylene fiber is increased to 25 parts.

[0084] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 425 parts of cement, 326 parts of modified steel slag powder, 178 parts of slag powder, 195 parts of silica fume, 4 parts of calcium sulfate whiskers, 25 parts of polyethylene fibers, 278 parts of water, 3 parts of water reducing agent and 1 part of thickener.

[0085] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 5% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 5 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0086] Dry-mix cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducer for 1 minute, and mix them evenly to obtain a cementitious material; add water and calcium sulfate whiskers to the cementitious material and mix well; then add the remaining water reducer and stir at 105 r / min for 1 minute; add a thickener and stir at 105 r / min for 1 minute; then add polyethylene fiber and stir at 105 r / min for 1 minute and then stir at 185 r / min for 2 minutes; disperse the fiber evenly in the cementitious material to obtain steel slag powder-based concrete.

[0087] After testing, the tensile strength of the specimen was 4.15MPa and the tensile strain capacity was 5.11%, but there was a large amount of fiber clumping.

[0088] Comparative Example 3

[0089] Compared with Example 3, the difference is that the steel slag powder is not subjected to any modification treatment.

[0090] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 405 parts of cement, 305 parts of steel slag powder, 175 parts of slag powder, 190 parts of silica fume, 3 parts of calcium sulfate whiskers, 12 parts of polyethylene fibers, 268 parts of water, 3 parts of water reducing agent and 1 part of thickener.

[0091] Cement, silica fume, slag powder, steel slag powder and half the weight of water reducing agent are dry-mixed for 3 minutes, and the mixture is evenly mixed to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducing agent is added and stirred at 110 r / min for 1 minute; a thickener is added and stirred at 110 r / min for 1 minute; polyethylene fibers are added and stirred at 110 r / min for 1 minute and then at 185 r / min for 4 minutes; the fibers are evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

[0092] After testing, the tensile strength of the specimen was 1.55MPa, and there was no steady-state cracking behavior and deformation capacity.

[0093] Comparative Example 4

[0094] Compared with Example 4, the difference is that no calcium sulfate whiskers are added.

[0095] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 400 parts of cement, 350 parts of modified steel slag powder, 150 parts of slag powder, 190 parts of silica fume, 8 parts of polyethylene fiber, 280 parts of water, 2 parts of water reducing agent and 1 part of thickener.

[0096] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 4% by mass of the steel slag powder, the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 6 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0097] Dry mix cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducer for 2 minutes, mix evenly to obtain a cementitious material; add water to the cementitious material and mix well; then add the remaining water reducer and stir at 120r / min for 2 minutes; add thickener and stir at 120r / min for 2 minutes; then add polyethylene fiber and stir at 120r / min for 2 minutes and then at 205r / min for 2 minutes; disperse the fiber evenly in the cementitious material to obtain steel slag powder-based concrete.

[0098] After testing, the tensile strength of the specimens cured at room temperature was 4.72MPa, and the tensile strain was 5.2%. However, the tensile strength and tensile strain of the specimens after high temperature were significantly lower than those of the specimens containing calcium sulfate whiskers.

[0099] Comparative Example 5

[0100] Compared with Example 5, the difference is that the polyethylene fiber is removed.

[0101] A steel slag powder-based concrete is composed of the following raw materials in parts by weight: 450 parts of cement, 300 parts of modified steel slag powder, 180 parts of slag powder, 205 parts of silica fume, 5 parts of calcium sulfate whiskers, 260 parts of water, 4 parts of water reducing agent and 2 parts of thickener.

[0102] The preparation method of the modified steel slag powder is specifically as follows: weigh an appropriate amount of steel slag powder, grind and sieve to obtain steel slag powder of 0.15-0.6 μm, weigh a potassium methyl silicate solution of 6% by mass of the steel slag powder, and the mass fraction of the potassium methyl silicate solution is 80%, slowly add it dropwise into a steel slag powder mixer stirred at a speed of 500 r / min within 7 minutes, continue stirring for 1 hour to obtain a crude product, and place the crude product in an oven at 105° C. and dry it for 6 hours to obtain formic acid modified steel slag powder SSM.

[0103] Cement, silica fume, slag powder, modified steel slag powder and half the weight of water reducer are dry-mixed for 3 minutes and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducer is added and stirred at 115 r / min for 2 minutes; a thickener is added and stirred at 115 r / min for 2 minutes to obtain steel slag powder-based concrete.

[0104] After testing, the specimen was found to have brittle failure and lacked ductility.

[0105] The properties of the steel slag powder-based concrete prepared in Examples 1 to 8 of the present invention and Comparative Examples 1 to 5 were tested, and the results are shown in Table 1.

[0106] Table 1 Mechanical properties of steel slag powder-based concrete of the present invention

[0107]

[0108] It can be seen from Table 1 that the steel slag powder-based concrete provided by the present invention has better mechanical properties, and its tensile strength and tensile strain capacity are strong. Compared with the examples, Comparative Example 1 is to reduce the weight of the polyethylene fiber in Example 1 from 14 parts to 1 part, Comparative Example 2 is to increase the weight of the polyethylene fiber in Example 1 from 14 parts to 25 parts, Comparative Example 3 is to not modify the steel slag powder in Example 3, Comparative Example 4 is to remove the calcium sulfate whisker in Example 4, and Comparative Example 5 is to remove the polyethylene fiber in Example 5. From the mechanical property data, it can be seen that the tensile strength and tensile strain of the obtained steel slag powder-based concrete are greatly affected, and the concrete specimens are brittlely damaged, have no steady-state cracking behavior and deformation capacity, and do not have ductility.

[0109] In summary, the cementitious material prepared by cement, steel slag powder, slag powder and silica fume can effectively cooperate with PE fiber. At the same time, calcium sulfate whiskers can also promote each other with PE fiber, enhance the toughness of steel slag powder-based concrete, and improve the stability at high temperature. 2 / kg of steel slag powder is modified and then added as an admixture to cement binder to produce ultra-high ductility concrete. When polyethylene fiber is added, the cement-based composite binder can better cooperate with each other, and the steel slag powder ultra-high ductility concrete exhibits more excellent mechanical properties.

[0110] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A steel slag powder-based concrete, characterized in that: The invention is composed of the following raw materials in parts by weight: 400-450 parts of cement, 300-350 parts of modified steel slag powder, 150-180 parts of slag powder, 190-205 parts of silica fume, 3-5 parts of calcium sulfate whisker, 8-20 parts of polyethylene fiber, 260-280 parts of water, 2-4 parts of water reducing agent and 1-2 parts of thickener; The preparation method of the modified steel slag powder is specifically as follows: grinding and sieving the steel slag powder, adding 4% to 6% of the mass of the steel slag powder potassium methyl silicate solution, the mass concentration of the potassium methyl silicate solution is 80%, stirring, and drying to obtain the modified steel slag powder; After grinding and screening, the particle size of the steel slag powder is 0.15 μm to 0.6 μm; the diameter of the calcium sulfate whisker is 1 μm to 8 μm, the length is 30 μm to 200 μm, the aspect ratio is 10 to 200, the CaSO4 content is ≥ 98%, the melting point is 1450°C, the water solubility is <1200 ppm, and the density is 2.69 g / cm 3 , tensile strength is 20.5GPa, tensile modulus is 178GPa, and pH value is 6-8.

2. The steel slag powder-based concrete according to claim 1, characterized in that: The modified steel slag powder has a specific surface area greater than 450 m 2 / kg, 7-day activity index ≥50%, 28-day activity index ≥65%.

3. The steel slag powder-based concrete according to claim 1, characterized in that: The silicon dioxide content in the slag powder is greater than 90%; the silicon ash is first-grade silicon ash with a specific surface area of ​​≥400m 2 / kg, particle size range is 25-100μm; the cement is ordinary Portland cement, initial setting time is greater than 45min, final setting time is less than 10h, and 28d strength is greater than or equal to 42.5MPa.

4. The steel slag powder-based concrete according to claim 1, characterized in that: The polyethylene fiber has a length of 10 mm to 30 mm, a diameter of 15 μm to 25 μm, an aspect ratio of ≥500, an elongation at break of 3% to 4%, an elastic modulus of ≥110 GPa, and a tensile strength of ≥2800 MPa.

5. The method for preparing steel slag powder-based concrete according to any one of claims 1 to 4, characterized in that: The following steps are involved: Weigh the following raw materials in parts by weight: 400-450 parts of cement, 300-350 parts of modified steel slag powder, 150-180 parts of slag powder, 190-205 parts of silica fume, 3-5 parts of calcium sulfate whiskers, 8-20 parts of polyethylene fiber, 260-280 parts of water, 2-4 parts of water reducer, and 1-2 parts of thickener; Cement, silica fume, slag powder, modified steel slag powder and part of water reducing agent are dry-mixed and mixed evenly to obtain a cementitious material; water and calcium sulfate whiskers are added to the cementitious material and mixed evenly; the remaining water reducing agent is added and stirred; a thickener is added and stirred; polyethylene fiber is added and stirred at 105 r / min to 125 r / min and then at 185 r / min to 205 r / min; the fiber is evenly dispersed in the cementitious material to obtain steel slag powder-based concrete.

6. The method for preparing steel slag powder-based concrete according to claim 5, characterized in that: The weight of the partial water reducing agent is 50% of the weight of the water reducing agent.

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