Superfine powder admixture and preparation method thereof

Abstract

The invention provides an ultrafine powder admixture and a preparation method thereof, the ultrafine powder admixture comprises a main material and / or an activator, the main material comprises slag, mining and mineral separation waste residue powder and fly ash, and the mass ratio of the slag to the mining and mineral separation waste residue powder to the fly ash is 4: 4: 2. According to the superfine powder admixture and the preparation method thereof, the superfine powder admixture is convenient to manufacture, the activity index of the superfine powder admixture is highest, the resource utilization rate is high, the cement clinker consumption can be reduced, and the solid waste utilization level can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of ultrafine powder materials, and in particular to an ultrafine powder admixture and a preparation method thereof. Background Art

[0002] The cement production process consumes a lot of energy and emits a large amount of polluting gases such as carbon dioxide, which has caused a serious burden on the environment. Some methods of carbon emission reduction in the cement industry have been proposed in related technologies, including reducing energy consumption, reducing the proportion of clinker in cement, using alternative fuels, carbon capture and storage, etc. The most important direction for cement development is to shift from producing ordinary Portland cement to producing composite cement, replacing part of the clinker with mixed materials. In some technologies, ultra-fine powder materials made of industrial solid waste such as tailings and blast furnace slag as the main raw materials will replace ordinary mixed materials, replace the proportion of clinker with solid waste resources, reduce the clinker coefficient in cement products, reduce cement clinker consumption, and improve the level of solid waste utilization.

[0003] Ultrafine composite mineral admixtures refer to powder materials that are made by mixing two or more mineral materials in a certain proportion and then ultra-finely grinding them. Mineral materials include slag powder, fly ash, limestone powder, mining waste residue powder, bottom slag and other waste residues. The fineness of the admixtures reaches the micron level. However, the activity index of existing ultrafine powder admixtures is relatively low, and the improvement of various properties after adding into cement is limited. Therefore, there is an urgent need for an ultrafine powder admixture with a high activity index. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide an ultrafine powder admixture and a preparation method thereof.

[0005] Based on the above-mentioned purpose, the first aspect of the present application provides an ultrafine powder admixture, including a main material and / or an activator, wherein the main material includes slag, mining and mineral processing waste slag powder and fly ash, and the mass ratio of the slag, the mining and mineral processing waste slag powder and the fly ash is 4:4:2.

[0006] Furthermore, the mass percentage of the activator to the main material is 0.2%.

[0007] Furthermore, the activator includes sodium silicate, sodium carbonate, triethanolamine and sodium dodecylbenzene sulfonate, and the mass ratio of the sodium silicate, the sodium carbonate, the triethanolamine and the sodium dodecylbenzene sulfonate is 6:1:6:5.

[0008] Furthermore, the average particle size of the ultrafine powder admixture is less than 45 μm.

[0009] The second aspect of the present application provides a method for preparing the ultrafine powder admixture as described in the first aspect above, comprising: first mixing the main materials in proportion, and / or adding an activator, and then grinding for 90 minutes to obtain the ultrafine powder admixture; or, first grinding each main material separately for 90 minutes, and then mixing the main materials in proportion, and / or adding an activator to obtain the ultrafine powder admixture.

[0010] From the above, it can be seen that the ultrafine powder admixture and its preparation method provided by the present application include a main material and / or an activator. The main material includes slag, mining and mineral processing waste slag powder and fly ash. The mass ratio of slag, mining and mineral processing waste slag powder and fly ash is 4:4:2. After testing, at this mass ratio, the 28d activity index of the ultrafine powder admixture is the highest. Too high or too low mass ratio will reduce the activity index. After the ultrafine powder admixture is added to cement, it can effectively improve the various properties of cement and reduce the clinker consumption in cement products. The ultrafine powder admixture and its preparation method are easy to make, the ultrafine powder admixture has the highest activity index, and the resource utilization rate is high. It can reduce the consumption of cement clinker and improve the level of solid waste utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0012] Figure 1 Micrographs of mining slag powder before and after grinding;

[0013] Figure 2 Micrographs of slag before and after grinding;

[0014] Figure 3 Micrographs of fly ash before and after grinding;

[0015] Figure 4 This is a test diagram of particle size and sphericity of different powder particles in the embodiments of this application;

[0016] Figure 5 This is an activity test diagram of different powders and ratios in the examples of this application;

[0017] Figure 6 This is a test diagram of the activity of the ultrafine powder admixture at different grinding times in the examples of this application;

[0018] Figure 7 This is a test diagram of particle size and sphericity of the ultrafine powder admixture at different grinding times in the examples of this application;

[0019] Figure 8 This is a test diagram of the activity of the ultrafine powder admixture under different amounts of activator in the examples of this application;

[0020] Fig. 9 These are electron microscope images of the ultrafine powder admixture in the examples of this application at the 3rd day and the 28th day. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments.

[0022] It should be noted that, unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0023] The cement production process consumes a lot of energy and emits a large amount of polluting gases such as carbon dioxide, which has caused a serious burden on the environment. Some methods of carbon emission reduction in the cement industry have been proposed in related technologies, including reducing energy consumption, reducing the proportion of clinker in cement, using alternative fuels, carbon capture and storage, etc. The most important direction for cement development is to shift from producing ordinary Portland cement to producing composite cement, replacing part of the clinker with mixed materials. In some technologies, ultra-fine powder materials made of industrial solid waste such as tailings and blast furnace slag as the main raw materials will replace ordinary mixed materials, replace the proportion of clinker with solid waste resources, reduce the clinker coefficient in cement products, reduce cement clinker consumption, and improve the level of solid waste utilization.

[0024] Ultrafine composite mineral admixtures refer to powder materials that are made by mixing two or more mineral materials in a certain proportion and then ultra-finely grinding them. Mineral materials include slag powder, fly ash, limestone powder, mining waste residue powder, bottom slag and other waste residues. The fineness of the admixtures reaches the micron level. However, the activity index of existing ultrafine powder admixtures is relatively low, and the improvement of various properties after adding into cement is limited. Therefore, there is an urgent need for an ultrafine powder admixture with a high activity index.

[0025] Fly ash is a volcanic ash-like mixed material formed after high-temperature combustion of coal powder. It is mainly solid waste discharged from coal-fired power plants, smelters, chemical industries and other industries. It is discharged from the furnace of the boiler along with the flue gas, and the flue gas and dust are separated by the dust collector. The dust is fly ash. Studies have shown that the activity of fly ash is significantly improved as the fineness decreases after ultra-fine grinding.

[0026] Granulated blast furnace slag is a water-extracted waste slag produced during the steelmaking process. It has a high water content and is difficult to grind in the existing processing process. The power consumption is high and a single powder is prone to agglomeration after prolonged grinding time. The particle size cannot be reduced continuously through grinding alone. The fatigue value of the ball mill medium increases after long-term operation, and the grinding efficiency decreases over a long period of time.

[0027] Mining ore dressing waste powder of natural volcanic ash is solid waste generated by sorting during the mining process, and its generation amount is about 10% to 20% of the finished product beneficiation output. At present, the main use of natural volcanic ash mining ore dressing waste powder is as a filler, filling in the roadbed, base layer and surface layer. Mining ore dressing waste powder has unique crystal nuclei and microspheres, performance (such as high compressive strength) and chemical properties (refractory, durability and stability, etc.) in ultrafine powder, and is widely used in infrastructure construction, sustainable development and low carbon dioxide emissions. Mining ore dressing waste powder has a three-dimensional aluminosilicate structure, connecting aluminum oxygen tetrahedron and silicon oxygen tetrahedron by sharing oxygen atoms. The chemical composition is similar to that of natural volcanic ash materials, but it is usually amorphous rather than crystalline. The principle is that amorphous silicon aluminum reacts with alkaline solution to form amorphous to semi-crystalline aluminosilicate inorganic polymers.

[0028] Generally speaking, polymerization is a complex multi-step process, which can be roughly divided into three steps: the amorphous phase in the raw material is dissolved by alkali solution to produce active silicon-aluminum phase; the dissolved precursor ions are redirected into monomers; these monomers undergo condensation reaction to form amorphous or semi-crystalline aluminosilicate geopolymers with a three-dimensional network structure. Therefore, any material composed of amorphous silica or alumina may be the source of ultrafine powder raw materials.

[0029] This application mainly studies the micro-nano ultrafine powders with mining ore dressing waste slag powder, blast furnace slag, fly ash and other industrial solid wastes as the main raw materials, aiming to solve environmental pollution and increase the added value of solid waste. It is added to ordinary silicate cement in the form of external admixture, which can not only improve the performance of cement and the adaptability of concrete, but also reduce the clinker coefficient in cement products. This method of producing low-carbon cement is one of the effective ways to reduce carbon, and it also reduces the production cost of cement. In the process of preparing fly ash and mining ore dressing waste slag powder, the activity is affected by factors such as its particle size, specific surface area, chemical composition and mineralogical characteristics; mechanical activation is studied to change the bonding of large glass particles, improve surface properties and aggregate grading, increase particle surface free energy, reduce the filling and encapsulation of a large amount of amorphous gel or tiny particles, and improve the physical activity of fly ash; an activator is studied to make the silicon dioxide and aluminum oxide in the volcanic ash material undergo hydrolysis reaction in alkaline solution to form aluminosilicate, so that the -Si-O-Si- or -Si-O-Al- bonds of the aluminosilicate are broken, releasing active Al 3+ and Si 4+substances, forming a silicate aluminum-based polymer with a new amorphous three-dimensional network structure; studying the effect of grinding time on the activity index of different ultrafine powders; studying the particle grading and performance changes after the multi-component ultrafine powders were added to P.O42.5 cement.

[0030] Below, through specific embodiments and combined Figures 1 to 9 To describe the technical solution of this application in detail.

[0031] In some embodiments of the present application, an ultrafine powder admixture is provided, including a main material and / or an activator, wherein the main material includes slag, mining and mineral processing waste slag powder and fly ash, and the mass ratio of the slag, the mining and mineral processing waste slag powder and the fly ash is 4:4:2.

[0032] When different main materials were ground individually, it was found that the activity index of slag could reach more than 95%, while that of mining waste slag powder was slightly lower than that of fly ash, both of which were less than 70%; various main materials were tested at different mass ratios, with the mass ratios of slag: mining waste slag powder: fly ash being 4:2:4, 4:3:3, 4:4:2, and 4:5:1, respectively. It was found that the activity of ternary mixed ball milling of slag, mining waste slag powder, and fly ash was higher than that of a single main material, and with the increase of the amount of mining waste slag powder in the ratio, the activity index first increased and then decreased. When the amount of mining waste slag powder was 40%, that is, the mass ratio was 4:4:2, the 28d activity index was the highest, which was 117%, far exceeding the activity index of pure slag ultrafine powder. It can be seen that the composite of multiple solid wastes can play a synergistic coupling role. After the physical excitation of ultrafine grinding, the lattice energy and surface energy of the material change. At the same time, the particle sizes of powders with different grindabilities are different. Reasonable ratio can adjust the grading of powder particles to achieve close stacking, which can effectively improve the activity of ultrafine powder.

[0033] Ultrafine high-activity mineral admixtures can be prepared by multi-component ultrafine grinding of slag, mining and ore dressing waste residue powder, and fly ash, and the advantages of each material can be fully utilized to achieve synergistic coupling to improve the overall performance of the material. The use of multi-solid waste composites to prepare ultrafine high-activity mineral admixtures through physical-chemical excitation, and the use of high-activity slag to drive low-activity mining and ore dressing waste residue powder can effectively improve the utilization rate of mining and ore dressing waste residue powder, reduce the preparation cost of high-quality mineral admixtures, and have important significance for alleviating environmental pressure and increasing the added value of difficult-to-treat industrial solid waste.

[0034] After the ultrafine powder admixture is added to cement, it can effectively improve various properties of cement and reduce the clinker consumption in cement products. The ultrafine powder admixture is easy to make, has the highest activity index, has high resource utilization, can reduce cement clinker consumption, and improve the level of solid waste utilization.

[0035] In some embodiments, the mass percentage of the activator to the host material is 0.2%.

[0036] The activator includes sodium silicate, sodium carbonate, triethanolamine and sodium dodecylbenzene sulfonate, and the mass ratio of the sodium silicate, the sodium carbonate, the triethanolamine and the sodium dodecylbenzene sulfonate is 6: 1: 6: 5. According to the test, at this mass percentage, the 28d activity index of the ultrafine powder admixture is the highest, and too low a mass percentage will reduce the activity index of the ultrafine powder admixture.

[0037] In some embodiments, the average particle size of the ultrafine powder blend is less than 45 μm.

[0038] According to the test, the average particle size can be less than 45μm after 90 minutes of grinding. The 28d activity index of the ultrafine powder admixture is high, and the 28d activity index of the ultrafine powder admixture larger than the average particle size is relatively low.

[0039] In some embodiments of the present application, a method for preparing an ultrafine powder admixture is provided, comprising: first mixing main materials in proportion, and / or adding an activator, and then grinding for 90 minutes to obtain an ultrafine powder admixture; or, first grinding each main material separately for 90 minutes, and then mixing the main materials in proportion, and / or adding an activator to obtain an ultrafine powder admixture.

[0040] Ball milling is to impact and crush the material through spherical grinding media. As the ball milling time increases, the material fineness will reach a critical point, at which point it is difficult to continue to refine. Ultrafine powder has the characteristics of high specific surface area, and adsorption and agglomeration are prone to occur on the surface, reducing the grinding efficiency. As the grinding time increases, the average particle size of ultrafine powder gradually decreases. When the grinding time exceeds a certain level, the agglomeration effect of ultrafine powder reduces the grinding efficiency. Too long grinding time will damage the spherical microbeads of fly ash. Although the destruction of the spherical microbeads can greatly improve the activity index of fly ash, its water demand ratio will increase significantly. Single addition will cause the rheological properties of the slurry to deteriorate and the slump loss to be large.

[0041] The mass ratio of slag: mining waste slag powder: fly ash is 4:4:2. When the grinding time is 90 minutes, the activity index of the ultrafine powder admixture can reach up to 117% at 28 days. The activity index decreases with the increase of grinding time, indicating that high-activity ultrafine mineral admixture can be prepared by grinding for 90 minutes. The average particle size of the powder after grinding for 90 minutes reaches a minimum of 3.88μm, and the average sphericity of the powder particles is the best; with the increase of grinding time, the sphericity of the ultrafine powder increases first and then decreases, and the average particle size decreases first and then slightly increases.

[0042] In addition, the test shows that the 28d activity index of the ultrafine powder admixture obtained by grinding each main material for 90 minutes separately and then mixing the main materials in proportion and / or adding an activator is higher than the 28d activity index of the ultrafine powder admixture obtained by first mixing the main materials in proportion and / or adding an activator and then grinding for 90 minutes.

[0043] Specifically, the raw materials were obtained. The slag came from Hejing Iron and Steel Plant, the fly ash came from Alaer Shengyuan Thermal Power Plant, the mining and ore dressing waste slag powder came from Aksu Youdi Trading Co., Ltd., the cement was P.O42.5 ordinary Portland cement, the activator was an alkaline organic-inorganic composite activator, the main components included sodium silicate with a modulus of 0.8 to 1.5, sodium carbonate, triethanolamine and sodium dodecylbenzene sulfonate, the mass ratio was 6:1:6:5, and it was a brown solution, the water was tap water, and the main chemical composition of each powder was shown in Table 1.

[0044] Table 1 Material composition

[0045]

[0046] The slag, mining waste residue powder and fly ash were ground separately using a test ball mill (SM-500×500). Figures 1 to 3 As shown, the left side of the figure is a micrograph before grinding, and the right side is a micrograph after grinding for 90 minutes, which was obtained by magnifying 287 times using a three-dimensional stereo microscope.

[0047] Depend on Figure 1 It can be seen that the raw material particles of mining ore dressing waste slag powder vary in size, and the apparent morphology is irregular hard particles; the structure of mining ore dressing waste slag powder after grinding is still dense, the particle size is uniform, and it is tightly attached together. When the mining ore dressing waste slag powder is ball milled, due to its hard texture, it can act as a grinding medium, which is conducive to further grinding the particles into smaller and more uniform ultrafine powder.

[0048] Depend on Figure 2 It can be seen that the slag raw material obtained by the water quenching process is a glassy material with clear edges and corners and a large number of pores distributed on the surface; the surface morphology of the slag powder particles after grinding is still irregular. Due to the brittleness of slag, it is easy to produce multi-angular powder particles through the ball milling process.

[0049] Depend on Figure 3 It can be seen that the unground fly ash contains a large number of spherical fly ash microbeads; after the ground fly ash, some of the spherical microbeads are destroyed to form ultrafine irregular particles.

[0050] Then the particle size and shape of cement, fly ash, fly ash after 90 minutes of grinding, slag after 90 minutes of grinding and mining waste residue powder after 90 minutes of grinding were measured respectively. The test results are shown in Table 2 and Figure 4 As shown in the figure, it can be seen that the average particle size of the unground fly ash (i.e., fly ash R) is similar to the average particle size of cement. The average particle size of the ground mining waste slag powder is the smallest, which is 1.65μm; the average particle size of fly ash is reduced by 1.58μm after grinding. It shows that the mining waste slag powder can be effectively ground into ultrafine powder, and grinding can effectively improve the particle size distribution of fly ash and increase the fineness of fly ash. The average sphericity of the ground mining waste slag powder is the largest, which is 0.83, indicating that the brittle mining waste slag powder can be made uniform through mechanical collision and friction during the ball milling process, which is beneficial to improve the particle morphology of the powder. The average sphericity of fly ash is significantly reduced after grinding, indicating that the microbead structure in the fly ash has been destroyed to a certain extent during the grinding process.

[0051] Table 2 Particle size and shape of various powders

[0052] Sample name Average particle size (μm) Average sphericity cement 5.92 0.718 Mining ore dressing waste powder 1.65 0.830 Fly ash R 5.67 0.777 Fly ash 4.09 0.758 slag 3.55 0.757

[0053] The activity of ultrafine powder admixtures under different main material ratios was studied. First, slag, mining waste residue powder and fly ash were ground for 90 min respectively, and the 7d activity index and 28d activity index were measured based on the activity index of cement. Then, the main materials were mixed in proportion, where the mass ratios of slag: mining waste residue powder: fly ash were 4:2:4, 4:3:3, 4:4:2, and 4:5:1, respectively. Then, 0.2% of the mass of the main material was added as an activator to obtain ultrafine powder admixtures. The 7d activity index and 28d activity index were also measured based on the activity index of cement. The test results are shown in Tables 3 and 4. Figure 5 shown.

[0054] As can be seen from the chart, when single powder is ground, the activity index of slag can reach more than 95%, and the activity index of mining waste slag powder is slightly lower than that of fly ash, both less than 73%; but the activity of slag, mining waste slag powder and fly ash after ternary compounding and ball milling is much higher than that of low-activity single mining waste slag powder and fly ash. The 28d activity index is optimal when the mass ratio of slag: mining waste slag powder: fly ash is 4:4:2, which is 117%, exceeding the activity index of pure slag ultrafine powder. It can be seen that the composite of multi-component solid waste can play its synergistic coupling role. After physical excitation of ultrafine grinding, the material undergoes changes in lattice energy and surface energy. At the same time, the particle sizes of powders with different grindability are different. Reasonable ratio can adjust the grading of powder particles to achieve close stacking, which can effectively improve the activity of ultrafine powder.

[0055] Table 3 Activity index table at different ratios

[0056]

[0057]

[0058] The activity of ultrafine powder admixture under different grinding time was studied. Slag, mining waste residue powder and fly ash were selected and mixed in a mass ratio of 4:4:2. The ultrafine powder admixture was obtained by grinding for 45min, 60min, 75min, 90min and 105min respectively. No activator was added. The 7d activity index and 28d activity index were measured based on the activity index of cement. The average particle size and average sphericity were also measured. The test results are shown in Table 4. Figure 6 and Figure 7 shown.

[0059] from Figure 6 It can be seen that when the grinding time is 90 minutes, the 28d activity index of the ultrafine powder admixture can reach up to 103%. As the grinding time continues to increase, the activity index decreases, indicating that high-activity ultrafine mineral admixtures can be prepared by grinding for 90 minutes. Figure 7 It can be seen that after 90 minutes of grinding, the average particle size of the powder reaches a minimum of 3.88μm, at which time the average sphericity of the powder particles is the best; with the increase of grinding time, the sphericity of the ultrafine powder first increases and then decreases, and the average particle size first decreases and then slightly increases. Ball milling is to impact and crush the material through spherical grinding media. With the increase of ball milling time, the fineness of the material will reach a critical point, at which time it is difficult to continue to refine, and ultrafine powder has the characteristics of high specific surface area, and adsorption and agglomeration are easy to occur on the surface, which reduces the grinding efficiency.

[0060] Table 4 Activity index table of different grinding time

[0061] Grinding time (min) 7d activity index 28d activity index Average particle size (μm) Average sphericity 45 0.72 0.94 4.83 0.711 60 0.68 0.88 4.41 0.715 75 0.70 0.95 4.30 0.732 90 0.67 1.03 3.88 0.750 105 0.76 0.96 4.15 0.745 cement 1.00 1.00 14.82 0.712

[0062] The activity of ultrafine powder admixtures under different activator dosages was studied. The main materials were selected as slag, mining waste residue powder and fly ash, which were mixed according to the mass ratio of 4:4:2. 0.02%, 0.10%, 0.15% and 0.20% of the mass of the main materials were added with activators, respectively. Then, the powder was ground for 90 minutes. The 7d activity index and 28d activity index were measured based on the activity index of cement. The test results are shown in Table 5 and Figure 8 shown.

[0063] As can be seen from the chart, the addition of different doses of stimulant has no obvious effect on improving the early activity index. With the increase of the stimulant dosage, the 7d activity index first decreases and then gradually increases; the stimulant dosage has a significant effect on the 28d activity index. With the increase of the stimulant dosage, the 28d activity index shows an overall increasing trend. When the dosage is 0.2%, the activity index reaches the maximum, and the 28d activity index increases by more than 10%. The addition of stimulant is beneficial to promote the hydration reaction process and improve the hydration activity of ultrafine admixtures.

[0064] Table 5 Activity index of different activator dosages

[0065] Activator dosage (%) 7d activity index 28d activity index 0.05 0.72 0.88 0.10 0.67 0.95 0.15 0.67 0.98 0.20 0.70 1.08 cement 1.00 1.00

[0066] Slag, mining waste residue powder and fly ash were selected and mixed in a mass ratio of 4:4:2, with a fixed grinding time of 90 minutes and an activator dosage of 0.2%. This was used as the preferred solution for ultrafine powder admixtures to study their hydration microscopic characteristics at different ages. Fig. 9 As shown, the left side is the SEM picture of the 3d-old under the optimal ratio, and the right side is the SEM picture of the 28d-old. It can be seen from the figure that more flocculent CSH gel and hexagonal CH are generated in the early hydration, there are tiny pores inside the cementitious material, and the spherical fly ash microbeads are clearly visible and have not yet undergone hydration reaction; with the extension of age, the internal flocculent CSH gel further increases, and under the secondary hydration of the ultrafine powder, the internal pores are reduced and the overall structure is more compact. As the ultrafine powder gradually undergoes a volcanic ash effect, the internal hexagonal CH calcium hydroxide content is reduced, the cementitious material is more completely hydrated, and the compressive strength can be increased.

[0067] To verify the effect of the ultrafine powder admixture of the preferred scheme in cement application, 18 parts by weight of ultrafine powder admixture were added to 100 parts by weight of cement of 4 brands, and compared with cement without ultrafine powder admixture, the cement characteristics and various properties were measured. The test results are shown in Tables 6 and 7.

[0068] Table 6 Cement characteristic test table

[0069]

[0070] Table 7 Cement performance test table

[0071]

[0072]

[0073] It can be seen from the table that after adding 18% ultrafine powder admixture, the 45μm sieve residue density of the four brands of cement all decreased, and the specific surface area all increased, which is in line with the law; the 3d strength of the four brands of cement decreased by 0.8MPa~1.8MPa, and the 28d strength increased by 1.2MPa~2.1MPa; for fluidity, 3 brands increased and 1 brand decreased; for standard viscosity, 3 brands increased slightly and 1 brand remained unchanged; the initial setting time and final setting time of the four brands of cement were slightly extended.

[0074] Through the above data on changes in particle size distribution and performance changes, it can be determined that after adding 18% ultrafine powder admixture to P.O42.5 cement, the clinker consumption in the cement product is correspondingly reduced. Due to the more reasonable particle grading, the 28d strength is significantly improved. In addition, the working performance of the cement and its adaptability to concrete are also improved.

[0075] In order to verify the application effect of ultrafine powder admixture in concrete, especially the change of long-term strength, samples were sent to the supervision and testing station, and ultrafine powder admixture was used to replace 25% and 35% of the benchmark cement. The S95 mineral powder with the highest compressive strength ratio was replaced by ultrafine powder admixture as a variable, and the compressive strength of the same age concrete was compared with that of the benchmark concrete. The test results are shown in Table 8.

[0076] Table 8 Concrete test table

[0077]

[0078] As can be seen from the table, ultrafine powder admixtures can greatly improve the activity of various minerals and give full play to their micro-aggregate effect and particle morphology effect; ultrafine powder is used in concrete to replace S95 mineral powder and part of cement, which can improve concrete strength and construction performance.

[0079] Ultrafine powder admixture is added to P.O42.5 cement by external mixing, which is a low-carbon cement production method that grinds and prepares cement separately. The amount of admixture is related to the mineral composition and proportion of clinker, the type of admixture, the particle grading of cement and other factors. The appropriate range is generally 8% to 15%. Calculated by adding 10% to 20% micro-nano ultrafine powder to P.O42.5 cement, clinker consumption can be reduced by 7% to 13%, and carbon emissions can be reduced by 0.06 tons to 0.11 tons for every ton of low-carbon cement produced.

[0080] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of simplicity.

[0081] The embodiments of the present disclosure are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. An ultrafine powder admixture, characterized in that: include: The main material and / or activator, the main material includes slag, mining and mineral processing waste slag powder and fly ash, and the mass ratio of the slag, the mining and mineral processing waste slag powder and the fly ash is 4:4:

2.

2. The ultrafine powder admixture according to claim 1, characterized in that: The mass percentage of the activator to the main material is 0.2%.

3. The ultrafine powder admixture according to claim 2, characterized in that: The activator comprises sodium silicate, sodium carbonate, triethanolamine and sodium dodecylbenzene sulfonate, and the mass ratio of the sodium silicate, the sodium carbonate, the triethanolamine and the sodium dodecylbenzene sulfonate is 6:1:6:

5.

4. The ultrafine powder admixture according to claim 1, characterized in that: The average particle size of the ultrafine powder admixture is less than 45 μm.

5. A method for preparing the ultrafine powder admixture according to any one of claims 1 to 4, characterized in that: include: Firstly, the main materials are mixed in proportion, and / or an activator is added, and then the ultrafine powder admixture is obtained by grinding for 90 minutes; Alternatively, each main material is first ground for 90 minutes, and then the main materials are mixed in proportion, and / or an activator is added to obtain an ultrafine powder admixture.

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