CN111302691A - Steel slag powder-ferromanganese slag powder composite admixture and preparation process thereof - Google Patents

Abstract

The invention discloses a steel slag powder-ferromanganese slag powder composite admixture and a preparation process thereof. The composite admixture comprises 5-30% of ferromanganese slag powder, 70%-95% of steel slag powder by weight, and the The preparation method is as follows: respectively drying, crushing, grinding, classifying or screening ferromanganese slag and steel slag to obtain ferromanganese slag powder and steel slag powder; then mixing the ferromanganese slag powder and steel slag powder uniformly according to the ratio The steel slag powder-ferromanganese slag powder composite admixture is obtained, wherein the performance of the steel slag powder meets the secondary technical requirements in the GB/T20491-2017 "Steel slag powder used in cement and concrete" standard. In the invention, the ferromanganese slag powder and the steel slag powder are mutually excited to produce the micro-aggregate effect, so as to improve the fluidity, compressive and flexural activities of the admixture in the cement mortar, increase the slump of the concrete over time, and improve the concrete resistance. Compressive and flexural strength.

Description

A steel slag powder-manganese iron slag powder composite admixture and its preparation process

technical field

The invention belongs to the technical field of building materials, and in particular relates to a steel slag powder-ferromanganese slag powder composite admixture and a preparation process thereof.

Background technique

Protecting the environment, reducing the consumption of natural resources and improving the performance of cement concrete are the two most important issues facing the field of cement and concrete. The application of concrete admixtures, on the one hand, can effectively control the total production volume of Portland cement, so that the existing industrial waste residue can be recycled and reused, thereby reducing the load on resources and the environment of the building materials industry itself and other industrial industries; On the one hand, concrete admixtures can significantly improve the mechanical properties, work performance, corrosion resistance and durability of concrete, and are an indispensable structural component of contemporary high-performance concrete. Therefore, how to use industrial waste residues, natural minerals and low-grade mineral admixtures to prepare high-strength and high-performance concrete is one of the current research hotspots.

Steel slag is the solid waste discharged during the steelmaking process, and the discharge amount of steel slag is generally about 15-20% of the steel output. In 2017, my country's crude steel output reached 832 million tons, accounting for 49.18% of the global total. The annual emission of steel slag in my country is about 133 million tons. A large amount of steel slag is left idle, which not only seriously pollutes the environment but also occupies land. Therefore, there is an urgent need to reduce, recycle and efficiently utilize steel slag. Research results in recent years have shown that the development of steel slag as a cement admixture or concrete admixture is likely to be an important way for its efficient and high value-added utilization. Steel slag is rich in minerals such as C ₃ S and C ₂ S, and is an industrial waste residue similar to inferior Portland cement clinker, which has the potential to be developed as a raw material for cement and concrete production. Steel slag powder can be used as auxiliary cementitious material to improve the wear resistance and impact resistance of cement concrete. As an auxiliary cementitious material, steel slag can reduce the use of cement clinker, which can not only reduce the pressure of the cement industry on resources, energy and the environment, but also solve the environmental problems caused by the iron and steel industry waste. Sustainable development has an irreplaceable win-win effect.

The ferromanganese slag has certain hydraulic and pozzolanic properties after being quenched and quenched by water. It is a material with high potential activity and has the value of application and development. At present, ferromanganese slag has not been fully developed and utilized in my country. Except 30% is used for cement admixture and smelting, the other 70% is used for landfill treatment, and the annual net emission is 12 million tons. The specific surface area of manganese slag used for cement admixture is about 420m ² /kg alone, and it is filled in composite form. The related research only stays in the research stage of mortar, and there is no manganese slag powder. Related research reports on the preparation of concrete fine admixtures for concrete.

SUMMARY OF THE INVENTION

Based on the above deficiencies of the prior art, considering that the steel slag powder has low early strength when used alone, while the ferromanganese slag powder has high activity, if the two composite steel slag powder and ferromanganese slag powder are mutually excited, it is expected to fill the The voids of the cement particles produce a micro-aggregate effect, thereby preparing a composite admixture with high early strength, continuous increase in late strength, and a compensating shrinkage effect. The technical problem solved by the present invention is to provide a steel slag powder-manganese iron slag powder composite admixture and a preparation process thereof, and the concrete mixed with the composite admixture has high compressive strength; the preparation process is simple, It is easy to operate, and can prepare composite admixtures with high early strength, continuous increase in late strength, and compensation for shrinkage.

In order to solve the above technical problems, the present invention provides a composite admixture of steel slag powder and ferromanganese slag powder, which comprises the following components by weight: 5-30% of ferromanganese slag powder, 70%-95% of steel slag powder, Among them, the performance of steel slag powder meets the secondary technical requirements in the GB/T20491-2017 "Steel slag powder used in cement and concrete" standard.

As the optimization of the above-mentioned technical scheme, the steel slag powder-ferromanganese slag powder composite admixture provided by the present invention further includes some or all of the following technical features:

As an improvement of the above technical solution, the median diameter D ₍₅₀₎ of the steel slag powder is ≤15 μm.

As an improvement of the above technical solution, the median diameter D ₍₅₀₎ of the ferromanganese slag powder is ≤10 μm.

As an improvement of the above technical solution, the specific surface area of the steel slag powder is 400-500 m ² /kg.

As an improvement of the above technical solution, the specific surface area of the ferromanganese slag powder is 400-600 m ² /kg.

A preparation process of steel slag powder-ferromanganese slag powder composite admixture, comprising the following steps:

1) ferromanganese slag and steel slag are respectively dried, crushed, pulverized, classified and screened to obtain ferromanganese slag powder and steel slag powder;

2) The ferromanganese slag powder and the steel slag powder are uniformly mixed according to the weight ratios of 5% to 30% and 70% to 95% to obtain a steel slag powder-ferromanganese slag powder composite admixture, wherein the performance of the steel slag powder meets GB /T20491-2017 "Steel slag powder used in cement and concrete" standard secondary technical requirements.

As the optimization of the above-mentioned technical scheme, the preparation process of the steel slag powder-ferromanganese slag powder composite admixture provided by the present invention further includes some or all of the following technical features:

As an improvement of the above technical solution, the median diameter D ₍₅₀₎ of the steel slag powder is ≤15 μm, and the specific surface area is 400-500 m ² /kg.

As an improvement of the above technical solution, the median diameter D ₍₅₀₎ of the ferromanganese slag powder is ≤10 μm, and the specific surface area is 400-600 m ² /kg.

As an improvement of the above technical solution, in the grinding process in the step 1), a grinding aid is mixed with triethanolamine as the main component, and the mixing amount of the triethanolamine is 0.02% to 0.05%.

Compared with the prior art, the technical scheme of the present invention has the following beneficial effects: the present invention, by mixing the secondary steel slag powder and the ferromanganese slag powder, utilizes the mutual excitation and synergy between the two to prepare a product with high early strength. , The composite admixture with continuous strength growth in the later stage. The composite admixture can obviously improve the fluidity of the cement cementitious material. In addition, C30-C50 grade high-strength concrete can be produced by mixing the composite admixture of the present invention with cement of the same quality, which has good compressive strength. The composite admixture of the invention can be mixed with cement in equal quality, and the mixing amount is extremely large, which significantly improves the utilization rate and resource utilization level of solid waste, and reduces the production cost of concrete materials.

The above description is only an overview of the technical solutions of the present invention, in order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand , in conjunction with the preferred embodiments, the detailed description is as follows.

Description of drawings

In order to describe the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings of the embodiments will be briefly introduced below.

Fig. 1 is the SEM image of the hydration product of cement slurry 7d of the embodiment of the present invention 1;

Fig. 2 is the SEM image of the 7d hydration product of cement-steel slag powder composite admixture pure slurry of Example 2 of the present invention;

Fig. 3 is the SEM image of 7d hydration product of cement-steel slag powder-manganese iron slag powder composite admixture pure slurry of the embodiment of the present invention;

Fig. 4 is the SEM image of the hydration product of cement slurry 28d in Example 1 of the present invention;

Fig. 5 is the SEM image of the 28d hydration product of the cement-steel slag powder composite admixture pure slurry of Example 2 of the present invention;

6 is a SEM image of the 28d hydration product of the cement-steel slag powder-manganese iron slag powder composite admixture pure slurry of Example 6 of the present invention.

Detailed ways

The specific embodiments of the present invention will be described in detail below. As part of this specification, the principles of the present invention will be illustrated by examples. Other aspects, features and advantages of the present invention will become apparent from the detailed description.

By mixing steel slag powder and ferromanganese slag powder, the invention uses the mutual excitation and synergy between the two to prepare a composite admixture with high early strength, continuous increase in late strength, and both compensation and shrinkage effects. The fluidity and compressive and flexural activity of the mixture in cement mortar can increase the slump of concrete over time and improve the compressive and flexural strength of concrete.

The ferromanganese slag powder-steel slag powder composite admixture of the present invention is prepared by the following process:

1) respectively drying, crushing, grinding, classifying or sieving ferromanganese slag and steel slag to obtain ferromanganese slag and steel slag powder;

Specifically, the ferromanganese slag is dried to a moisture content of less than 1%, then crushed to a particle size of less than 4.75mm using a jaw crusher, and then ground with a 5kg ball mill and mixed with 0.03% of Triethanolamine grinding aid is finally passed through a 0.9mm sieve to obtain a ferromanganese slag powder with a Brinell specific surface area of 456m ² /kg, a density of 2.81g/cm ^{3 and} a median diameter D ₍₅₀₎ ≤10μm.

Dry the steel slag to a moisture content of less than 1%, then use a jaw crusher to crush it to a particle size of less than 4.75mm, then use a 5kg ball mill to grind and mix 0.03% triethanolamine grinding aid during the grinding process, Finally, pass through a 0.9 mm sieve to obtain steel slag powder with a specific surface area of 410 m ² /kg, a density of 3.41 g/cm ³ and a median diameter D ₍₅₀₎ ≤ 15 μm.

2) Mixing the steel slag powder and the ferromanganese slag powder uniformly according to a certain proportion to obtain the ferromanganese slag powder-steel slag powder composite admixture.

<Table 1> Composition ratio of steel slag powder - ferromanganese slag powder composite admixture

Please refer to Table 2, which reflects the chemical composition of the ferromanganese slag micropowder and the steel slag micropowder in the composite admixture.

The steel slag powder in the composite admixture of the present invention contains more CaO, Fe ₂ O ₃ and SiO ₂ , while the ferromanganese slag powder mainly contains SiO ₂ , Al ₂ O, CaO and MnO. It can be seen that ferromanganese Slag powder has more active ingredients than steel slag powder.

<Table 2> Chemical composition of ferromanganese slag powder and steel slag powder

Please refer to Table 3. The table shows that the various proportions of ferromanganese slag powder-steel slag powder composite admixtures in Table 1 are mixed with cement according to the weight ratio of 1:3, and then the cement is obtained according to the water-to-binder ratio of 0.5. Mortar, and then according to GB/T20491-2017 "Steel Slag Powder for Cement and Concrete" standard, the test results of steel slag micropowder mortar test. As a comparison, a cement mortar not admixed with the composite admixture of the present invention was prepared as a blank sample at the same time. Table 3 reflects the fluidity of the cement mortar (Example 2-Example 7) mixed with 30% ferromanganese slag powder-steel slag powder composite admixture compared with the cement mortar (blank sample) using cement alone It is 103.5%～106.5% of blank sample. It shows that the mixing of ferromanganese slag powder-steel slag powder composite admixture can significantly improve the fluidity of cement.

<Table 3> Steel slag powder - manganese iron slag powder composite admixture cement mortar test results

Please refer to Table 4. Table 4 is the activity index obtained by processing the data results of Table 3 according to the activity calculation method in the standard GB/T20491-2017 "Steel Slag Powder for Cement and Concrete". Compared with the cement mortar (blank sample) of cement, the compressive strength activity index and flexural strength of the cement mortar (Example 2-Example 7) mixed with 30% ferromanganese slag powder-steel slag powder composite admixture The activity index has declined. According to the technical requirements of GB/T20491-2017 "Steel Slag Powder for Cement and Concrete", the activity index of first-grade steel slag powder is not less than 65% for 7d and not less than 80% for 28d; the activity of secondary steel slag powder is not less than 80%. Index 7d is not less than 55%, and 28d is not less than 65%. The 7d and 28d activity indices of the 6 samples from Example 2 to Example 7 all meet the technical requirements for secondary steel slag powder in GB/T20491-2017. The activity of 7d is 67.4%, and the activity of 28d is 80.3%, meeting the technical requirements of first-grade steel slag powder.

At the same time, three groups of examples of Example 1, Example 2 and Example 6 in Table 1 were selected to make a clean slurry test block according to GB/T1346-2011 "Standard for Water Consumption, Setting Time, and Stability Test Method for Standard Consistency of Cement", Samples were made after standard curing for 28 days, and the microscopic morphology of the fresh sections of the samples at each hydration age was observed with a scanning electron microscope (SEM) in vacuum mode, as shown in Figures 1-6. Among them, Figure 1 reflects the microscopic morphology of the hydration product of Example 1 (blank sample). Figure 1 shows that the hydration products of the standard curing 7d pure cement paste are mainly fibrous C-S-H gel and flaky CH, and have relatively There are many holes (black), and there are many unhydrated particles (white). Figure 2 reflects the microscopic morphology of the hydration product of Example 2. It can be seen in Figure 2 that the hydration product of standard curing 7d cement-steel slag powder slurry It is still fibrous C-S-H gel and sheet-like CH, but the pores are significantly reduced, and the unhydrated part is also reduced compared with the pure cement sample. Figure 3 reflects the microscopic morphology of the hydration product of Example 6. It can be seen from Figure 3 that the hydration product of the cement-steel slag powder-manganese iron slag powder slurry after curing for 7d is similar to the first two groups, but the number of pores is the least and there is no water. The chemical part is also the least compared with the first two groups. It can be seen that after the addition of steel slag powder and ferromanganese slag powder, the early hydration products of the composite admixture are more, and the unhydrated part and voids are less. The early hydration of the raw materials has a promoting effect.

Figure 4 reflects the microscopic morphology of the hydration product of Example 1 (blank sample). Figure 1 shows that the section of the standard curing 28d pure cement paste is relatively dense, and the C-S-H gel and CH are interwoven into a whole. At the same time, the network C-S-H gel is relatively dense, so the strength of the cement mortar is higher at this time. Figure 5 reflects the microscopic morphology of the hydration product of Example 2. It can be seen from Figure 5 that the hydration product of the standard curing 28d cement-steel slag powder slurry has more holes in the section than the standard curing 28d pure cement slurry section. In addition, the C-S-H in the section are mainly spherical particles and fibrous. It can be seen that the hydration degree of the composite admixture after adding the steel slag powder is lower than that of the pure cement sample. Figure 6 reflects the microscopic morphology of the hydration product of Example 6. It can be seen in Figure 6 that the cross section of the hydration product of the standard curing 28d cement-steel slag powder-manganese iron slag powder slurry is basically the same as that of the pure cement sample. The reticulated C-S-H gel is very dense. It can be seen that the addition of ferromanganese slag powder can effectively speed up the hydration process of the composite admixture, which can also explain the ratio of steel slag powder-ferromanganese slag powder-cement composite admixture. Compared with the traditional steel slag powder-cement composite admixture, it has more excellent cementitious properties.

<Table 4> Steel slag powder-ferromanganese slag powder composite admixture cement mortar activity index test results

Table 5 is a design scheme for commercial concrete with strength grades of C30 to C50. River sand with a fineness modulus of 3.4 is used as fine aggregate, and limestone crushed stone with particle size of 5 to 25 mm is continuously graded as coarse aggregate. The mixing ratio is designed as follows: cement 16.0%, natural river sand 25.6%, stone 52.0%, water reducing agent 0.03%, and mixing water 6.4%. The specific steps are: weigh 2502.5g of P.O42.5 cement, (wherein Example 8 is a blank sample of pure cement, and Example 9 is a mixture of 75% steel slag powder and 25% ferromanganese slag powder to replace 30% Cement by weight) 3991g of natural river sand, 8105.5g of stones of 5-25mm particle size (including 2026g of 5-10mm particle size, 4052g of 10-20mm particle size, 2026g of 20-25mm particle size), 4.0g of polycarboxylate water reducer , 1001g of mixing water, and then put it into a concrete mixer to mix evenly, and then prepare concrete test blocks according to GB/T50081-2002 "Mechanical Properties Test Method of Ordinary Concrete" to detect slump, slump over time, compressive strength strength, flexural strength, etc. The test results of its mechanical properties are shown in Table 5.

<Table 5> Mechanical properties test results of steel slag powder - ferromanganese slag powder composite admixture of hydrated concrete

It can be seen from Table 5 that both the initial slump and the slump with time of Example 9 are higher than those of the blank sample (Example 8), especially the slump with time. The compressive and flexural strength is slightly reduced, but all meet the design standards.

Compared with the prior art, the present invention prepares a composite admixture with high early strength and continuous increase of late strength by mixing secondary steel slag powder and ferromanganese slag powder and utilizing the mutual excitation and synergy between the two. The composite admixture can obviously improve the fluidity of the cement cementitious material. In addition, C30-C50 grade high-strength concrete can be produced by mixing the composite admixture of the present invention with cement of the same quality, which has good compressive strength. The composite admixture of the invention can be mixed with cement in equal quality, and the mixing amount is extremely large, which significantly improves the utilization rate and resource utilization level of solid waste, and reduces the production cost of concrete materials.

Each raw material listed in the present invention, as well as the upper and lower limits and interval values of each raw material in the present invention, as well as the upper and lower limits and interval values of process parameters (such as temperature, time, etc.) can realize the present invention, and will not be listed one by one here. Example.

The above descriptions are only the preferred embodiments of the present invention, of course, it cannot limit the scope of rights of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, Several improvements and changes are made, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims (9)

1. a steel slag powder-ferromanganese slag powder composite admixture is characterized in that comprising the following components by weight: ferromanganese slag powder 5～30%, steel slag powder 70%～95%, wherein steel slag powder performance It meets the second-level technical requirements in the GB/T20491-2017 "Steel Slag Powder for Cement and Concrete" standard. 2 . The steel slag powder-ferromanganese slag powder composite admixture according to claim 1 , wherein the median diameter D ₍₅₀₎ of the steel slag powder is less than or equal to 15 μm. 3 . 3 . The steel slag powder-ferromanganese slag powder composite admixture of claim 1 , wherein the median diameter D ₍₅₀₎ of the ferromanganese slag powder is less than or equal to 10 μm. 4 . 4 . The steel slag powder-manganese iron slag powder composite admixture according to claim 1 , wherein the specific surface area of the steel slag powder is 400-500 m ² /kg. 5 . 5 . The steel slag powder-ferromanganese slag powder composite admixture of claim 1 , wherein the specific surface area of the ferromanganese slag powder is 400-600 m ² /kg. 6 . 6. a preparation technology of steel slag powder-ferromanganese slag powder composite admixture, is characterized in that comprising the following steps: 1) ferromanganese slag and steel slag are respectively dried, crushed, pulverized, classified and screened to obtain ferromanganese slag powder and steel slag powder; 2) The ferromanganese slag powder and the steel slag powder are uniformly mixed according to the weight ratios of 5% to 30% and 70% to 95% to obtain a steel slag powder-ferromanganese slag powder composite admixture, wherein the performance of the steel slag powder meets GB /T20491-2017 "Steel slag powder used in cement and concrete" standard secondary technical requirements. 7. The preparation process of steel slag powder-manganese iron slag powder composite admixture according to claim 1, characterized in that: the steel slag powder median diameter D ₍₅₀₎ ≤15μm, and the specific surface area is 400～500m ² /kg. 8. the preparation technology of steel slag powder-ferromanganese slag powder composite admixture as claimed in claim 1, is characterized in that: described ferromanganese slag powder median diameter D ₍₅₀₎ ≤10μm, and specific surface area is 400 ~600m ² /kg. 9. the preparation technology of steel slag powder-manganese iron slag powder composite admixture as claimed in claim 1, it is characterized in that: described in the step 1), the grinding process is mixed with triethanolamine as main component grinding aid The dosage of the triethanolamine is 0.02% to 0.05%.

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