Mineral admixture for concrete as well as preparation method and application of mineral admixture

Abstract

The invention discloses a mineral admixture for concrete as well as a preparation method and application of the mineral admixture. The mineral admixture comprises the following components in parts by mass: 30-50 parts of steel slag micropowder; 5 to 15 parts of phosphogypsum; 5 to 15 parts of silica fume; 10 to 25 parts of fly ash; 0.1 to 1 part of modified chitosan fiber; 1 part to 10 parts of an exciting agent; the modified chitosan fibers are polyglutamic acid modified chitosan fibers. The mineral admixture is prepared from the steel slag micro powder, the phosphogypsum, the silica fume, the fly ash, the modified chitosan fiber and the exciting agent, so that the durability and the compressive strength of the concrete can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete, in particular to a mineral admixture for concrete, a preparation method and application thereof. BACKGROUND

[0002] With the development of modern concrete technology, the components in the concrete include mineral admixtures in addition to cement, coarse and fine aggregates, water reducing agent and water; the mineral admixture refers to inorganic mineral powder added during the preparation of concrete to improve the performance of fresh concrete and hardened concrete, and the fineness is the same as or finer than that of cement. Common mineral admixtures include fly ash, granulated blast furnace slag, silica fume, limestone powder, steel slag powder, phosphorus slag powder, zeolite powder, and composite mineral admixture.

[0003] Although the mineral admixture is widely used, its application still faces significant technical bottlenecks in the pursuit of high performance and multifunctional modern concrete engineering practice. For example, two or more admixtures are often used in engineering (such as fly ash and mineral powder) to make up for each other. However, this simple physical compounding often fails to achieve optimal synergy and balance of performance. The differences in the optimal dosage range, reaction rate, particle size distribution complementarity, and water reducing agent adsorbability of different admixtures interact, so that while meeting one or several performance (such as high compressive strength), other key performance (such as crack resistance or impermeability) may be sacrificed. For example, high strength and impermeability may require high silica fume, but will worsen the workability and crack resistance; good workability and crack resistance may depend on fly ash, but will weaken early strength and frost resistance.

[0004] Therefore, it is necessary to develop a mineral admixture for concrete, so that the concrete has good compressive strength and durability. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present application provides a mineral admixture for concrete, which can effectively improve the compressive strength and durability of the concrete.

[0006] The second aspect of the present application further provides a preparation method of the mineral admixture for concrete.

[0007] The third aspect of the present application further provides an application of the mineral admixture for concrete.

[0008] According to the first aspect of the present application, a mineral admixture for concrete is provided; comprising the following components calculated by mass fraction:

[0009] 30-50 parts of steel slag powder; 5-15 parts of phosphogypsum; 5-15 parts of silica fume; 10-25 parts of fly ash; 0.1-1 part of modified chitosan fiber; 1-10 parts of activator;

[0010] The modified chitosan fiber is a polyglutamic acid modified chitosan fiber.

[0011] According to a preferred embodiment of the present application, the composition comprises the following components by mass fraction:

[0012] Steel slag micro powder 35-40 parts; phosphogypsum 8-12 parts; silica fume 6-10 parts; fly ash 15-20 parts; modified chitosan fiber 0.3-0.8 parts; activator 2-5 parts.

[0013] According to a preferred embodiment of the present application, the modified chitosan fiber is prepared by the following method:

[0014] S1, mixing, defoaming polyglutamic acid, chitosan, crosslinking agent and water to prepare a spinning solution;

[0015] S2, electrospinning the spinning solution, namely.

[0016] According to a preferred embodiment of the present application, the electrospinning parameters are: push-injection speed 0.05-0.2 mm / min; spinning temperature 25-30℃; receiving distance 10-20 cm; positive pressure 8-25 kV; negative pressure -3--0.2 kV.

[0017] According to a preferred embodiment of the present application, the crosslinking agent comprises glutaraldehyde.

[0018] According to a preferred embodiment of the present application, the activator comprises at least one of alkali metal sulfate, alkali metal silicate, alkali metal phosphate, alkali metal oxalate, alkali metal formate or alkali metal hydroxide.

[0019] According to a preferred embodiment of the present application, the activator comprises at least one of sodium silicate, sodium sulfate or sodium hydroxide.

[0020] According to a preferred embodiment of the present application, the fly ash is selected from at least one of first grade fly ash or second grade fly ash.

[0021] According to a preferred embodiment of the present application, the cement is selected from at least one of Portland cement or sulphoaluminate cement.

[0022] According to a preferred embodiment of the present application, the specific surface area of the silica fume is 18 m 2 / g-25 m 2 / g, and the SiO2 content of the silica fume is >92wt%.

[0023] According to a preferred embodiment of the present application, the specific surface area of the steel slag micro-powder is 450-500 m 2 / kg.

[0024] According to a preferred embodiment of the present application, the specific surface area of the steel slag micro-powder is 480-500 m 2 / kg.

[0025] According to a preferred embodiment of the present application, the particle size of the steel slag micro-powder is preferably 25-75 μm, and more preferably 40-60 μm.

[0026] According to a preferred embodiment of the present application, the preparation method of the steel slag micro-powder preferably comprises the following steps: removing iron from steel slag tailings, and then performing crushing and screening in sequence to obtain the steel slag micro-powder; the crushing equipment is preferably roller mill and vertical mill; and the screening equipment is preferably a powder classifier.

[0027] The mineral admixture for concrete according to the embodiments of the present application has at least the following beneficial effects:

[0028] The mineral admixture according to the present application, which is prepared from steel slag micro-powder, phosphogypsum, silica fume, fly ash, modified chitosan fiber and activator, can improve the durability and strength of concrete. This is because the nano-filling effect of silica fume, the micro-aggregate effect of fly ash, and the generation and interweaving of a large amount of hydration products (C-S-H gel, ettringite, etc.) jointly act to significantly reduce the total porosity of the concrete.

[0029] Further, the steel slag and the phosphogypsum can generate ettringite and brushite, and can significantly improve the strength.

[0030] Further, on one hand, the polyglutamic acid modified chitosan fiber in the present application is chemically bonded with C-S-H gel to form a "reinforced concrete" nanostructure, which improves the toughening effect of the concrete and inhibits the generation of cracks; on the other hand, the polyglutamic acid modified chitosan fiber can block the penetration of chloride ions.

[0031] According to a second aspect of the present application, a method for preparing the mineral admixture for concrete according to the first aspect of the present application is provided, comprising the following steps:

[0032] The steel slag micro-powder, the phosphogypsum, the silica fume, the fly ash, the modified chitosan fiber and the sodium alginate-carbon nanotube composite material are mixed to obtain the mineral admixture for concrete.

[0033] The third aspect of the present application provides an application of the mineral admixture for concrete as described above in the preparation of a concrete product.

[0034] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. DETAILED DESCRIPTION

[0035] The following are specific embodiments of the present application, and the technical solutions of the present application are further described in conjunction with the embodiments, but the present application is not limited to these embodiments.

[0036] The reagents, methods and equipment used in the present application are all conventional reagents, methods and equipment in the technical field unless otherwise specified.

[0037] Some raw materials in the examples and comparative examples of the present application are as follows:

[0038] Cement: PO42.5 Portland cement, purchased from China Resources Cement;

[0039] Fly ash: secondary fly ash, commercially available;

[0040] Activator: sodium sulfate; commercially available.

[0041] Silica fume: BK-94; purchased from Shandong Bo Ken Silicon Material Co., Ltd.;

[0042] Steel slag micro-powder: specific surface area of 480-500 m 2 / kg; particle size of 40-60 μm; purchased from Hebei Yansixi Mineral Product Processing Factory.

[0043] The preparation of modified chitosan fibers is as follows:

[0044] S1, polyglutamic acid 10 parts by weight, chitosan 10 parts by weight, glutaraldehyde 2 parts by weight and 100 parts by weight of water were mixed and dissolved; stirred uniformly, and left to deaerate to obtain a spinning solution;

[0045] S2, the spinning solution was electrospun and vacuum dried. The electrospinning parameters were as follows: push injection speed of 0.2 mm / min; spinning temperature of 28℃; receiving distance of 15 cm; positive pressure of 20 kV; and negative pressure of -2 kV.

[0046] The preparation of chitosan fibers is as follows:

[0047] S1, chitosan 20 parts by weight, glutaraldehyde 2 parts by weight and 100 parts by weight of water were mixed and dissolved; stirred uniformly, and left to deaerate to obtain a spinning solution;

[0048] S2, the spinning solution was electrospun and vacuum dried. The electrospinning parameters were as follows: push injection speed of 0.2 mm / min; spinning temperature of 28℃; receiving distance of 15 cm; positive pressure of 20 kV; and negative pressure of -2 kV.

[0049] Example 1

[0050] This example provides a mineral admixture for concrete; the component content is shown in Table 1, and the preparation steps are as follows:

[0051] The steel slag micro-powder, phosphogypsum, silica fume, fly ash, modified chitosan fiber and sodium alginate-carbon nanotube composite material are mixed in proportion to obtain the mineral admixture.

[0052] Examples 2-5

[0053] Examples 2-5 provide a series of mineral admixtures for concrete, the component amount of which is shown in Table 1, and the preparation steps are the same as those of Example 1.

[0054] Table 1 Examples 1-5 (parts by weight)

[0055]

[0056] Comparative Example 1

[0057] Comparative Example 1 provides a mineral admixture for concrete, the preparation method and amount of which are the same as those of Example 1, and the difference lies in that chitosan fiber is used instead of modified chitosan fiber.

[0058] Comparative Example 2

[0059] Comparative Example 1 provides a mineral admixture for concrete, the preparation method and amount of which are the same as those of Example 1, and the difference lies in that no modified chitosan fiber is added.

[0060] Performance test

[0061] The mineral admixtures prepared in Examples 1-5 and Comparative Examples 1-2 of the present application are used to prepare C40 concrete; the raw material ratio is as follows: cement 200 parts; fly ash 70 parts; mineral admixture of the example or comparative example 100 parts; machine-made sand 900 parts; crushed stone 920 parts; polycarboxylic acid water reducer 8 parts; water 170 parts;

[0062] The preparation steps are as follows: S1, the cement, fly ash, mineral admixture of the example or comparative example, machine-made sand and crushed stone are mixed and stirred to uniformly mix them;

[0063] S2, the polycarboxylic acid water reducer and water are uniformly added to the product obtained in step S1 during stirring, and continue to stir uniformly to obtain cement concrete;

[0064] S3, after the pouring process is completed, secondary troweling is performed, and the surface of the initial setting concrete is appropriately sprinkled with water, and the method of laying "plastic film + geotextile" is used for heat preservation and moisture conservation, and the rain cloth surface is water stored, and the water spraying and water storage temperature is 30℃, and the mold is maintained for 7d.

[0065] Chloride ion permeability coefficient: tested according to GB / T 50082-2009 "Standard for testing methods for long-term performance and durability of ordinary concrete".

[0066] Compressive strength: tested according to GB / T 50081-2019 "Standard for test methods of physical and mechanical properties of concrete". The results are shown in Table 2.

[0067] Table 2

[0068]

[0069] As can be seen from the data in Table 2, the mineral admixture of the present application using steel slag micro-powder, phosphogypsum, silica fume, fly ash, modified chitosan fiber and activator as raw materials can improve the durability and strength of concrete. Especially when the raw materials of the mineral admixture are in the following ranges; steel slag micro-powder 35-40 parts; phosphogypsum 8-12 parts; silica fume 6-10 parts; fly ash 15-20 parts; modified chitosan fiber 0.3-0.8 parts; activator 2-5 parts. It has better compressive strength and durability.

[0070] The above has been described in detail in combination with the embodiments of the present application, but the present application is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the purpose of the present application.

Claims

1. A mineral admixture for concrete, characterized in that: It includes the following components calculated by mass: 30-50 parts of steel slag powder; 5-15 parts of phosphogypsum; 5-15 parts of silica fume; 10-25 parts of fly ash; 0.1-1 part of modified chitosan fiber; 1-10 parts of activator; The modified chitosan fiber is polyglutamic acid modified chitosan fiber.

2. The mineral admixture for concrete according to claim 1, characterized in that: It includes the following components calculated by mass: 35-40 parts of steel slag powder; 8-12 parts of phosphogypsum; 6-10 parts of silica fume; 15-20 parts of fly ash; 0.3 to 0.8 parts of modified chitosan fiber; 2 to 5 parts of activator.

3. The mineral admixture for concrete according to claim 1 or 2, characterized in that: The modified chitosan fiber is prepared by the following method: S1, mixing polyglutamic acid, chitosan, a cross-linking agent and water, and degassing to prepare a spinning solution; S2, electrospinning the spinning solution to obtain.

4. The mineral admixture for concrete according to claim 1 or 2, characterized in that: The activator includes at least one of alkali metal sulfate, alkali metal silicate, alkali metal phosphate, alkali metal oxalate, alkali metal format or alkali metal hydroxide.

5. The mineral admixture for concrete according to claim 1 or 2, characterized in that: The fly ash is selected from one of primary fly ash and secondary fly ash.

6. The mineral admixture for concrete according to claim 1 or 2, characterized in that: The cement is selected from at least one of Portland cement and sulphoaluminate cement.

7. The mineral admixture for concrete according to claim 1 or 2, characterized in that: The specific surface area of ​​the silica fume is 18m 2 / g~25m 2 / g, the SiO2 content of silica fume is >92wt%.

8. The mineral admixture for concrete according to claim 1 or 2, characterized in that: The specific surface area of ​​the steel slag powder is 450-500m 2 / kg.

9. A method for preparing the mineral admixture for concrete according to any one of claims 1 to 8, characterized in that: The steps include: The composite material is prepared by mixing steel slag micro powder, phosphogypsum, silica fume, fly ash, modified chitosan fiber and sodium alginate-carbon nanotube composite material.

10. Use of the mineral admixture for concrete according to any one of claims 1 to 8 in preparing concrete products.

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