Steel slag solid waste-based cementitious material, preparation method and application thereof

Abstract

This invention provides a cementitious material based on steel slag solid waste, comprising fly ash, slag, steel slag, and a composite activator, wherein the composite activator includes an alkaline activator, a sulfate activator, nano-hydrated calcium silicate, and polyvinyl butyral. This invention optimizes setting time, improves early and late strength, and enhances volume stability by employing a composite activator to synergistically activate the cementitious activity of fly ash, slag, and steel slag. This cementitious material can replace a portion of cement in concrete, mortar, roadbed materials, etc., achieving efficient utilization of industrial solid waste.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to cementitious materials based on steel slag solid waste, their preparation methods, and applications. Background Technology

[0002] The steel smelting process generates a large amount of industrial solid waste, mainly including fly ash, slag and steel slag.

[0003] Slag, a glassy solid waste formed by the rapid quenching of molten calcium aluminosilicate produced during pig iron smelting in blast furnaces, possesses potential hydraulic cementitious properties. Due to its high reactivity, slag is commonly used as a mineral admixture in cement and concrete, partially replacing cement, reducing heat of hydration, and improving later-stage strength. However, the reactivity of slag depends on alkaline activation; when used alone, its early strength development is slow, requiring combination with other activation methods to improve its cementitious efficiency.

[0004] Steel slag is a byproduct of steelmaking, primarily composed of dicalcium silicate (C2S) and tricalcium silicate (C3S). Its dense structure and high crystallinity result in low hydration activity. While steel slag can improve the workability of concrete, reduce water demand, and exhibit a certain pozzolanic effect as an admixture, its cementitious activity requires chemical or physical activation to be fully realized. Currently, chemical activators (such as NaOH and Na2SiO3) are commonly used industrially to activate steel slag, but this is costly and can easily cause shrinkage cracking in cementitious materials, affecting long-term durability. Therefore, developing low-cost, efficient, and stable steel slag activation technology is crucial.

[0005] Fly ash is a fine-particle solid waste emitted from coal-fired power plants, mainly composed of SiO2, Al2O3, and CaO, and possesses certain pozzolanic activity. While fly ash can improve the later-stage strength of cement-based materials, its low early-stage activity leads to slow strength development in the cementitious system. Existing research often employs alkaline activation or mechanical activation to enhance the reactivity of fly ash, but a single activation method is insufficient to simultaneously optimize setting time and mechanical properties.

[0006] As can be seen from the above, fly ash, slag, and steel slag exhibit significant differences in cementitious activity, and each has limitations when used individually. How to synergistically regulate the hydration process of these three materials through composite activation methods to achieve reasonable setting time, good volume stability, and to meet compressive and flexural strength requirements remains a technical challenge in this field. Existing technologies mostly focus on the utilization of single solid wastes, lacking optimized design for multi-solid-waste synergistic cementation systems, especially the development of low-cost, high-performance activators. Summary of the Invention

[0007] The purpose of this invention is to provide a cementitious material based on steel slag solid waste, its preparation method, and its application, so as to solve the above-mentioned technical problems existing in the prior art.

[0008] To solve the above-mentioned technical problems, the present invention provides a steel slag solid waste-based cementitious material, which includes fly ash, slag, steel slag, and a composite activator, wherein the composite activator includes an alkaline activator, a sulfate activator, nano-hydrated calcium silicate, and polyvinyl butyral.

[0009] Furthermore, the alkaline activator includes at least one or more of NaOH and Na2SiO3; the sulfate activator includes at least one or more of Na2SO4 and CaSO4.

[0010] Furthermore, the composite activator also includes triethanolamine.

[0011] Furthermore, it also includes additives, including iron-magnesium additives, which are borosilicate powder.

[0012] Furthermore, the composite activator is composed of NaOH, Na2SiO3, Na2SO4, nano-hydrated calcium silicate, polyvinyl butyral, and triethanolamine.

[0013] Furthermore, by weight, the composite activator is composed of 2-5 parts NaOH, 3-7 parts Na2SiO3, 1-3 parts Na2SO4, 1-3 parts nano-hydrated calcium silicate, 0.1-1.0 parts polyvinyl butyral and 0.1-0.5 parts triethanolamine;

[0014] Preferably, the composite activator is composed of 3-4 parts NaOH, 5-6 parts Na2SiO3, 1-2 parts Na2SO4, 1-3 parts nano-hydrated calcium silicate, 0.1-1.0 parts polyvinyl butyral and 0.1-0.5 parts triethanolamine;

[0015] Preferably, the composite activator is composed of 3.2 parts NaOH, 5.8 parts Na2SiO3, 1.2 parts Na2SO4, 1.5 parts nano-hydrated calcium silicate, 0.3 parts polyvinyl butyral, and 0.2 parts triethanolamine.

[0016] Furthermore, the weight ratio of the polyvinyl butyral to the Na2SO4 is 1:3 to 1:5;

[0017] Preferably, the weight ratio of polyvinyl butyral to Na2SO4 is 1:4.

[0018] Furthermore, by weight, it includes 20-40 parts fly ash, 30-50 parts slag, 10-30 parts steel slag, 5-15 parts composite activator, and 0-5 parts additives.

[0019] Preferably, by weight, it comprises 20-28 parts fly ash, 40-45 parts slag, 22-30 parts steel slag, 10-15 parts composite activator, and 2-3 parts additives.

[0020] Furthermore, by weight, it comprises 28 parts fly ash, 42 parts slag, 22 parts steel slag, 12 parts composite activator, and 2 parts boron-magnesium iron ore powder.

[0021] Preferably, by weight, it comprises 20 parts fly ash, 42 parts slag, 30 parts steel slag, 12 parts composite activator, and 3 parts boron-magnesium iron ore powder.

[0022] Furthermore, fly ash, slag, and steel slag are crushed, then mixed in proportion and stirred for 5-60 minutes. Then, composite activator and additives are added, and stirring is continued for 5-60 minutes to ensure uniform dispersion.

[0023] The metallurgical slag-based inorganic cementitious material prepared as described above can be used alone or / and mixed with clinker.

[0024] By adopting the above technical solution, the present invention has the following beneficial effects:

[0025] This invention utilizes a composite activator to synergistically activate the cementitious activity of fly ash, slag, and steel slag, optimizing setting time, improving early and late strength, and enhancing volume stability. This cementitious material can replace a portion of cement in concrete, mortar, roadbed materials, etc., achieving efficient utilization of industrial solid waste. Detailed Implementation

[0026] The present invention will now be described clearly and completely in conjunction with its technical solutions. Obviously, the described embodiments are only a part of, and not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] The present invention will be further explained below with reference to specific embodiments.

[0028] The main components (mass fraction %) of the raw materials used in the examples and comparative examples are shown in the table below:

[0029] materials silicon iron aluminum calcium magnesium <![CDATA[SO3]]> LOSS slag 31.83 3.21 15 35.78 10.24 0.34 - fly ash 42.96 5.04 33.75 4.3 2 2.49 7.39 steel slag 13.92 20.18 4.42 43.96 9.43 - -

[0030] (I) Implementation Examples

[0031] Example 1:

[0032] The preparation method of the steel slag solid waste-based cementitious material is as follows:

[0033] Crush 28 parts fly ash, 42 parts slag, and 22 parts steel slag, then mix and stir for 20 minutes. Then add 12 parts composite activator and 2 parts additives, and continue stirring for 15 minutes to ensure uniform dispersion.

[0034] The composite activator consists of 3.2 parts NaOH, 5.8 parts Na2SiO3, 1.2 parts Na2SO4, 1.5 parts nano-hydrated calcium silicate, 0.3 parts polyvinyl butyral, and 0.2 parts triethanolamine.

[0035] The manufacturer's model number for nano-hydrated calcium silicate is Xinyi Synthetic S7045;

[0036] The additive used is borosilicate powder.

[0037] Example 2:

[0038] The preparation method of the steel slag solid waste-based cementitious material is as follows:

[0039] Crush 20 parts fly ash, 42 parts slag, and 30 parts steel slag, then mix and stir for 20 minutes. Then add 12 parts composite activator and 3 parts additives, and continue stirring for 15 minutes to ensure uniform dispersion.

[0040] The composite activator consists of 3.5 parts NaOH, 5.8 parts Na2SiO3, 1.2 parts Na2SO4, 1.5 parts nano-hydrated calcium silicate, 0.3 parts polyvinyl butyral, and 0.2 parts triethanolamine.

[0041] The manufacturer's model number for nano-hydrated calcium silicate is Xinyi Synthetic S7045;

[0042] The additive used is borosilicate powder.

[0043] Comparative Example 1:

[0044] The only difference from Example 1 is that no nano-hydrated calcium silicate was added to the composite activator; specifically, the composite activator is composed of 3.2 parts NaOH, 5.8 parts Na2SiO3, 1.2 parts Na2SO4, 0.3 parts polyvinyl butyral and 0.2 parts triethanolamine.

[0045] Comparative Example 2:

[0046] The only difference from Example 1 is that polyvinyl butyral was not added to the composite activator; specifically, the composite activator is composed of 3.2 parts NaOH, 5.8 parts Na2SiO3, 1.2 parts Na2SO4, 1.5 parts nano-hydrated calcium silicate and 0.2 parts triethanolamine;

[0047] The manufacturer's model number for nano-hydrated calcium silicate is Xinyi Synthetic S7045.

[0048] Comparative Example 3:

[0049] The only difference from Example 1 is that Na2SO4 was not added to the composite activator; specifically, the composite activator is composed of 3.2 parts NaOH, 5.8 parts Na2SiO3, 1.5 parts nano-hydrated calcium silicate, 0.3 parts polyvinyl butyral and 0.2 parts triethanolamine;

[0050] The manufacturer's model number for nano-hydrated calcium silicate is Xinyi Synthetic S7045.

[0051] Comparative Example 4:

[0052] The only difference from Example 1 is that polyvinyl butyral and Na2SO4 were not added to the composite activator; specifically, the composite activator is composed of 3.2 parts NaOH, 5.8 parts Na2SiO3, 1.5 parts nano-hydrated calcium silicate and 0.2 parts triethanolamine.

[0053] The manufacturer's model number for nano-hydrated calcium silicate is Xinyi Synthetic S7045.

[0054] Comparative Example 5:

[0055] The only difference from Example 1 is that the composite activator is different; specifically, the composite activator is composed of 3.2 parts NaOH and 5.8 parts Na2SiO3.

[0056] Comparative Example 6:

[0057] The only difference from Example 1 is that the composite activator is different; specifically, the composite activator is composed of 1.2 parts Na2SO4, 1.5 parts nano-hydrated calcium silicate, 0.3 parts polyvinyl butyral and 0.2 parts triethanolamine.

[0058] The manufacturer's model number for nano-hydrated calcium silicate is Xinyi Synthetic S7045.

[0059] Comparative Example 7:

[0060] The only difference from Example 1 is that no boron-magnesium iron ore powder was added.

[0061] (II) Performance Testing

[0062] (1) Test method

[0063] Setting time: The initial setting and final setting times were determined using the test method in standard GB / T 1346-2011.

[0064] Compressive strength: The 3-day and 28-day strengths were determined using the test methods in standard GB / T 17671-2021.

[0065] Volume stability was determined according to standard GB / T 50082-2024.

[0066] (2) Test Results

[0067]

[0068]

[0069] Based on Example 1 and Comparative Examples 1-5, it can be seen that the absence of polyvinyl butyral leads to dehydration and shrinkage of the gel structure; the absence of Na2SO4 results in a decrease in its early compressive strength; the absence of nano-hydrated calcium silicate reduces both its compressive strength and volume stability; and based on Example 1 and Comparative Example 6, the lack of an initial high-alkali environment provided by NaOH leads to an increase in setting time.

[0070] As demonstrated in Example 1 and Comparative Examples 1-7, this invention optimizes setting time, improves early and late strength, and enhances volume stability by employing a composite activator to synergistically activate the cementitious activity of fly ash, slag, and steel slag. This cementitious material can replace a portion of cement in concrete, mortar, roadbed materials, etc., achieving efficient utilization of industrial solid waste.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Steel slag solid waste-based cementitious material, characterized by, By weight, it consists of 20-40 parts fly ash, 30-50 parts slag, 10-30 parts steel slag, 5-15 parts composite activator and 2-5 parts additives; The composite activator, by weight, consists of 2-5 parts NaOH, 3-7 parts Na2SiO3, 1-3 parts Na2SO4, 1-3 parts nano-hydrated calcium silicate, 0.1-1.0 parts polyvinyl butyral, and 0.1-0.5 parts triethanolamine. The weight ratio of polyvinyl butyral to Na2SO4 is 1:3-1:5; The additive is borosilicate powder.

2. The steel slag solid waste-based cementitious material according to claim 1, characterized in that, The composite activator, by weight, consists of 3.2 parts NaOH, 5.8 parts Na2SiO3, 1.2 parts Na2SO4, 1.5 parts nano-hydrated calcium silicate, 0.3 parts polyvinyl butyral, and 0.2 parts triethanolamine.

3. The steel slag solid waste-based cementitious material of claim 1, wherein, By weight, it comprises 28 parts fly ash, 42 parts slag, 22 parts steel slag, 12 parts composite activator, and 2 parts additives.

4. The method for preparing the steel slag solid waste-based cementitious material according to claim 1, characterized in that, Crush fly ash, slag, and steel slag, then mix them in proportion and stir for 5-60 minutes. Then add the composite activator and additives, and continue stirring for 5-60 minutes to ensure uniform dispersion.

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