Steel slag-based solid waste cementing material and composition design method

Abstract

The invention discloses a steel slag-based solid waste cementing material and a composition design method, and belongs to the technical field of steel slag resource utilization. The formula of the steel slag-based solid waste cementing material comprises the following components in percentage by mass: 20-35% of steel slag, 50-65% of mineral slag, 2-10% of desulfurized gypsum and 10% of cement. According to the method, the optimal alkalinity value is determined by detecting the content of CaO, SiO2, Al2O3 and MgO in the raw material steel slag and slag, the optimal dosage of the steel slag and slag is calculated according to the relationship between the alkalinity value and the alkalinity coefficient, and then the optimal proportion is obtained, so that the efficiency of ingredient ratio design is improved, and the time cost is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel slag resource utilization, and in particular relates to a steel slag-based solid waste cementitious material and a composition design method. Background Art

[0002] The comprehensive utilization of bulk industrial solid wastes such as steel slag is crucial to the overall management of solid wastes. It is an important measure to achieve industrial transformation and upgrading, and it is also one of the strategic guidelines to ensure the green and sustainable development of industry. The complex and changeable elemental composition, mineral type and physical and chemical properties of industrial solid wastes have seriously restricted the large-scale promotion and high-value application of solid waste materials. Many common industrial solid wastes such as converter slag, blast furnace slag and fly ash are mainly composed of aluminosilicate minerals, which have certain gelling activity and can be hydrated under alkaline conditions to generate hydration products such as calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) gel with similar structure and properties to cement stone. Therefore, industrial solid waste can be used as raw materials or auxiliary cementitious materials to replace part of cement.

[0003] At present, based on the workability, mechanical properties and durability of solid waste cementitious materials such as mortar, solid waste concrete and solid waste improved soil, many studies have been conducted to design the composition of multi-component solid waste cementitious materials by using experimental design methods such as single factor proportioning method, multi-factor proportioning method, empirical proportioning method, orthogonal experimental design method, response surface method and artificial neural network. However, due to the influence of factors such as the origin of raw materials, formation process, treatment method and aging time, the variability of various properties of the adapted cementitious materials is also large, even though the cementitious materials with the same components have different properties. The changes in these factors have a great influence on the performance of the final prepared cementitious materials. Therefore, the performance of cementitious materials prepared using solid waste as raw materials, especially the strength, often deviates from expectations. Therefore, industrial solid waste used in cementitious materials needs to provide a unified, standardized and refined grading and classification standard, and there is a lack of composition design methods for preparing relatively stable cementitious materials with solid waste raw materials of different properties and sources. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a steel slag-based solid waste cementitious material and a composition design method. The composition of the steel slag-based solid waste cementitious material is designed based on the intrinsic parameters of the steel slag raw materials such as particle fineness, chemical composition and degree of crystallization, and the research and preparation of steel slag-based multi-solid waste cementitious materials are carried out to provide a reference for improving the resource utilization and high-value utilization of bulk industrial solid waste such as steel slag. The cementitious material utilizes a variety of industrial solid wastes with complex components, and the method can realize the rapid design of the proportion of solid waste cementitious materials.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical purposes: A steel slag-based solid waste cementitious material, which comprises the following raw materials by mass percentage: 20-35% steel slag, 50-65% slag, 2-10% desulfurized gypsum and 10% cement.

[0007] Preferably, the steel slag-based solid waste cementitious material comprises the following raw materials, by mass percentage: 21-32% steel slag, 52-63% slag, 6% desulfurized gypsum and 10% cement.

[0008] Further preferably, the steel slag-based solid waste cementitious material comprises the following raw materials, by mass percentage: 31.75% steel slag, 52.25% slag, 6% desulfurized gypsum and 10% cement.

[0009] Furthermore, the steel slag meets the standard limit requirements of GB / T 20491-2017 "Steel slag powder used in cement and concrete", and the specific surface area is 450-550m 2 / kg.

[0010] Furthermore, the grade of the slag is S95 or above, the CaO content is ≥30wt.%, and the Al2O3 content is ≥13wt.%.

[0011] Furthermore, the desulfurized gypsum complies with the restriction requirements of the standard GB / T 21371-2008 "Industrial By-product Gypsum Used in Cement", and the radioactivity meets the requirements of the standard GB 6566-2010 "Limits of Radioactive Nuclides in Building Materials".

[0012] Furthermore, the cement is ordinary Portland cement with a strength grade of 42.5 or above.

[0013] Technical purpose 2: A method for designing the composition of the steel slag-based solid waste cementitious material, comprising the following steps:

[0014] S1. Prepare raw materials such as steel slag, slag, desulfurized gypsum and cement;

[0015] S2. Determine the contents of CaO, SiO2, Al2O3 and MgO in steel slag and ore slag, and calculate the basicity value p of steel slag according to formula (1):

[0016] p=CaO / (SiO2+P2O5)(wt.%) (1)

[0017] In the formula of steel slag-based solid waste cementitious material with the best mechanical properties, the relationship between the basicity value p of steel slag and the basicity coefficient M of steel slag and slag is as follows:

[0018] When the alkalinity value p varies between 1.30-1.80, the corresponding alkalinity coefficient M is between 0.9-1.1;

[0019] S3. After determining the basicity coefficient M of the steel slag and the slag and knowing the chemical components in the steel slag and the slag, calculate the mass percentages x and y of the steel slag and the slag in the cementitious material according to Equations (2) - (7);

[0020] A = xa1 + ya2 (2)

[0021] B = xb1 + yb2 (3)

[0022] C = xc1 + yc2 (4)

[0023] D = xd1 + yd2 (5)

[0024]

[0025] x + y + 0.1 = 1 (7)

[0026] Wherein, a1 is the content of CaO in the steel slag, wt%; a2 is the content of CaO in the slag, wt%;

[0027] b1 is the content of SiO2 in the steel slag, wt%; b2 is the content of SiO2 in the slag, wt%;

[0028] c1 is the content of Al2O3 in the steel slag, wt%; c2 is the content of Al2O3 in the slag, wt%;

[0029] d1 is the content of MgO in the steel slag, wt%; d2 is the content of MgO in the slag, wt%;

[0030] A, B, C, and D are the total contents of CaO, SiO2, Al2O3, and MgO in the steel slag-based solid waste cementitious material, respectively, wt%;

[0031] x is the mass percentage of the steel slag in the steel slag-based solid waste cementitious material, %; y is the mass percentage of the slag in the steel slag-based solid waste cementitious material, %;

[0032] S4. To make the slag-based solid waste cementitious material have high early strength and a wide range of applications, 10 wt% of ordinary Portland cement is incorporated into the formulation. Calculating the mass percentage of the desulfurized gypsum according to a content of 100 wt%.

[0033] Furthermore, when the alkalinity value 1.3 < p ≤ 1.5, the basicity coefficient M = 0.95;

[0034] When the alkalinity value 1.5 < p ≤ 1.6, the basicity coefficient M = 1.00;

[0035] When the alkalinity value 1.6 < p ≤ 1.7, the basicity coefficient M = 1.05;

[0036] When the alkalinity value is 1.7<p≤1.8, the alkalinity coefficient M=1.10.

[0037] Compared with the prior art, the present invention has the following advantages and technical effects:

[0038] The present invention prepares green and low-carbon cementitious materials by utilizing the hydration synergistic effect between various solid wastes. No other chemical reagents need to be added during the preparation process, which significantly improves the utilization rate of industrial solid waste and has good economic, social and environmental benefits. In addition, the steel slag-based solid waste cementitious material composition design method provided by the present invention is simple and quick to operate. The method can realize the rapid design of the solid waste cementitious material mix ratio, reduce the experimental workload, greatly improve the efficiency of the proportioning ratio design, and save time costs. At the same time, it also effectively reduces the human errors caused by the empirical method, improves the accuracy of the production of solid waste-based cementitious materials, and is suitable for large-scale production and market needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0040] Figure 1 Compressive strength of steel slag-based solid waste cementitious materials with different basicities;

[0041] Figure 2 Schematic diagram of the design method for the composition of steel slag-based solid waste cementitious materials. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0044] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0045] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0046] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0047] A method for designing the composition of steel slag-based solid waste cementitious materials comprises the following steps:

[0048] S1. Prepare raw materials such as steel slag, slag, desulfurized gypsum and cement;

[0049] S2. Determine the contents of CaO, SiO2, Al2O3 and MgO in steel slag and ore slag, and calculate the basicity value p of steel slag according to formula (1):

[0050] p=CaO / (SiO2+P2O5)(wt.%) (1)

[0051] In the formula of steel slag-based solid waste cementitious material with the best mechanical properties, the relationship between the basicity value p of steel slag and the basicity coefficient M of steel slag and slag is as follows:

[0052] When the alkalinity value is 1.3<p≤1.5, the alkalinity coefficient M=0.95;

[0053] When the alkalinity value is 1.5<p≤1.6, the alkalinity coefficient M=1.00;

[0054] When the alkalinity value is 1.6<p≤1.7, the alkalinity coefficient M=1.05;

[0055] When the alkalinity value is 1.7<p≤1.8, the alkalinity coefficient M=1.10;

[0056] S3. After determining the basicity coefficient M of the steel slag and the mineral slag and knowing the chemical composition of the steel slag and the mineral slag, the mass percentages x and y of the steel slag and the mineral slag in the cementitious material are calculated according to formulas (2) to (7);

[0057] A=xa1+ya2 (2)

[0058] B=xb1+yb2 (3)

[0059] C=xc1+yc2 (4)

[0060] D=xd1+yd2 (5)

[0061]

[0062] x+y+0.1=1 (7)

[0063] Wherein, a1 is the content of CaO in steel slag, wt%; a2 is the content of CaO in slag, wt%;

[0064] b1 is the content of SiO2 in steel slag, wt%; b2 is the content of SiO2 in slag, wt%;

[0065] c1 is the content of Al2O3 in steel slag, wt%; c2 is the content of Al2O3 in slag, wt%;

[0066] d1 is the content of MgO in steel slag, wt%; d2 is the content of MgO in slag, wt%;

[0067] A, B, C, and D are the total contents of CaO, SiO2, Al2O3, and MgO in the steel slag-based solid waste cementitious materials, wt%;

[0068] x is the mass percentage of steel slag in the steel slag-based solid waste cementitious material, %; y is the mass percentage of slag in the steel slag-based solid waste cementitious material, %;

[0069] S4. In order to make the slag-based solid waste cementitious material have higher early strength and wider application range, 10wt% ordinary Portland cement is added into the mix, and the mass percentage of desulfurized gypsum is calculated based on 100wt% content.

[0070] The above method can be used to obtain a steel slag-based solid waste cementitious material, which includes the following raw materials by mass percentage: 20-35% steel slag, 50-65% slag, 2-10% desulfurized gypsum and 10% cement.

[0071] Controlling the mass proportion of desulfurized gypsum below 10% can ensure that the total mass of steel slag and slag accounts for more than 80% of the mass of raw materials, which can improve the quality of solid waste cementitious materials.

[0072] In the following preferred embodiments of the present invention, the steel slag meets the standard limit requirements of GB / T 20491-2017 "Steel slag powder for cement and concrete", and the specific surface area is 450-550m2 / kg.

[0073] In the following preferred embodiments of the present invention, the slag is blast furnace slag of grade S95 or higher, with a CaO content of ≥30wt.%, and an Al2O3 content of ≥13wt.%.

[0074] In the following preferred embodiments of the present invention, the desulfurized gypsum complies with the standard restriction requirements of GB / T 21371-2008 "Industrial By-product Gypsum Used in Cement", and the radioactivity meets the requirements of GB 6566-2010 "Limits of Radioactive Nuclides in Building Materials".

[0075] In some preferred embodiments of the present invention, the cement is ordinary Portland cement with a strength grade of 42.5 or above.

[0076] The composition design method of steel slag-based solid waste cementitious material provided by the present invention only needs to detect the mass content of CaO, SiO2, Al2O3 and MgO in the raw materials steel slag and ore slag, and after calculating the alkalinity value of the batch of steel slag, the alkalinity coefficient of the cementitious material with the best mechanical properties can be found out accordingly. The test results of the chemical composition of the raw materials are substituted into formula (6) and formula (7), and the proportion of steel slag and ore slag in the cementitious material can be obtained by solving them.

[0077] The "normal temperature" mentioned in the present invention refers to 20-30°C unless otherwise specified.

[0078] The raw materials used in the present invention are all purchased from the market.

[0079] The technical solution of the present invention is further illustrated by the following embodiments.

[0080] Examples 1-6

[0081] This embodiment provides a method for calculating the ingredients of all-solid waste cementitious materials. The raw materials of the all-solid waste cementitious materials are steel slag (SS), slag (GBFS), desulfurized gypsum (DG) and cement (OPC). The composition design method of steel slag-based solid waste cementitious materials includes the following steps:

[0082] S1: Prepare raw materials: steel slag, slag, desulfurized gypsum and cement: Steel slag is ground to obtain a specific surface area of ​​450-550m 2 / kg steel slag powder; the slag grade is S95 slag powder, CaO content ≥ 30wt.%, Al2O3 content ≥ 13wt.%; the cement grade is 42.5 ordinary Portland cement;

[0083] S2: The chemical composition of steel slag and slag was tested by XRF, mainly including the content of CaO, SiO2, Al2O3 and MgO. The test results are shown in Table 1 and Table 2;

[0084] The basicity value p of steel slag is calculated according to formula (1):

[0085] p=CaO / (SiO2+P2O5)(wt.%) (1)

[0086] The basicity value p of steel slag and the basicity coefficient M of steel slag and slag satisfy the following relationship:

[0087] When the alkalinity value is 1.3<p≤1.5, the alkalinity coefficient M=0.95;

[0088] When the alkalinity value is 1.5<p≤1.6, the alkalinity coefficient M=1.00;

[0089] When the alkalinity value is 1.6<p≤1.7, the alkalinity coefficient M=1.05;

[0090] When the alkalinity value is 1.7<p≤1.8, the alkalinity coefficient M=1.10;

[0091] S3, calculating the mass percentages x and y of steel slag and slag in the cementitious material according to equations (2) to (7);

[0092] A=xa1+ya2 (2)

[0093] B=xb1+yb2 (3)

[0094] C=xc1+yc2 (4)

[0095] D=xd1+yd2 (5)

[0096]

[0097] x+y+0.1=1 (7)

[0098] Wherein, a1 is the content of CaO in steel slag, wt%; a2 is the content of CaO in slag, wt%;

[0099] b1 is the content of SiO2 in steel slag, wt%; b2 is the content of SiO2 in slag, wt%;

[0100] c1 is the content of Al2O3 in steel slag, wt%; c2 is the content of Al2O3 in slag, wt%;

[0101] d1 is the content of MgO in steel slag, wt%; d2 is the content of MgO in slag, wt%;

[0102] A, B, C, and D are the total contents of CaO, SiO2, Al2O3, and MgO in the steel slag-based solid waste cementitious materials, wt%;

[0103] x is the mass percentage of steel slag in the steel slag-based solid waste cementitious material, %; y is the mass percentage of slag in the steel slag-based solid waste cementitious material, %;

[0104] S4, 10% ordinary Portland cement content is fixed, according to 100wt% content, calculate the mass percentage of desulfurized gypsum;

[0105] S5: According to step S4, each component is weighed in proportion and mixed evenly to obtain the cementitious material. The formula of the obtained steel slag-based solid waste cementitious material is shown in Table 3.

[0106] Table 1 Chemical composition of steel slag with different basicity

[0107]

[0108] Table 2 Chemical composition of blast furnace slag

[0109] chemical composition CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO <![CDATA[Fe2O3]]> <![CDATA[SO3]]> other GBFS 32.10 30.35 20.06 10.15 0.25 2.78 4.31

[0110] Table 3 Formula of steel slag-based solid waste cementitious materials

[0111]

[0112]

[0113] The above-obtained cementitious material was cured at room temperature, and the compressive strength test was carried out according to the national standard GB / T 17671-2021 "Test method for strength of cement mortar (ISO method)". The test results are shown in Table 4.

[0114] Table 4 Test results of compressive strength of 7d and 28d cementitious materials

[0115]

[0116] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A steel slag-based solid waste cementitious material, characterized in that: By mass percentage, it includes the following raw materials: 20-35% of steel slag, 50-65% of slag, 2-10% of desulfurized gypsum, and 10% of cement.

2. The steel slag-based solid waste cementitious material according to claim 1, characterized in that: By mass percentage, it includes the following raw materials: 25-33% of steel slag, 51-58% of slag, 6% of desulfurized gypsum, and 10% of cement.

3. The steel slag-based solid waste cementitious material according to claim 1, characterized in that: By mass percentage, it includes the following raw materials: 32.34% of steel slag, 51.66% of slag, 6% of desulfurized gypsum, and 10% of cement.

4. The steel slag-based solid waste cementitious material according to claim 1, characterized in that: The specific surface area of ​​the steel slag is 450-550m 2 / kg.

5. The steel slag-based solid waste cementitious material according to claim 1, characterized in that: The level of the slag is S95 and above, the CaO content is ≥30 wt.%, and the Al2O3 content is ≥13 wt.%.

6. The steel slag-based solid waste cementitious material according to claim 1, characterized in that: The cement selected is ordinary Portland cement with a strength grade of 42.5 and above.

7. A method for designing the composition of steel slag-based solid waste cementitious materials according to any one of claims 1 to 6, characterized in that: It includes the following steps: S1. Prepare raw materials of steel slag, slag, desulfurized gypsum, and cement; S2. Measure the contents of CaO, SiO2, Al2O3, and MgO in the steel slag and slag, and calculate the basicity value p of the steel slag according to formula (1): p = CaO / (SiO2 + P2O5) (wt.%) (1) In the formula for the steel slag-based solid waste cementitious material with the best mechanical properties, the relationship between the basicity value p of the steel slag and the basicity coefficient M of the steel slag and slag is as follows: When the basicity value p varies between 1.30 and 1.80, the corresponding basicity coefficient M is between 0.9 and 1.1; S3. When the basicity coefficient M of the steel slag and slag is determined and the chemical components in the steel slag and slag are known, calculate the mass percentages x and y of the steel slag and slag in the cementitious material according to formulas (2)-(7); A = xa1 + ya2 (2) B = xb1 + yb2 (3) C = xc1 + yc2 (4) D = xd1 + yd2 (5) x + y + 0.1 = 1 (7) Wherein, a1 is the content of CaO in the steel slag, wt%; a2 is the content of CaO in the slag, wt%; b1 is the content of SiO2 in the steel slag, wt%; b2 is the content of SiO2 in the slag, wt%; c1 is the content of Al2O3 in the steel slag, wt%; c2 is the content of Al2O3 in the slag, wt%; d1 is the content of MgO in the steel slag, wt%; d2 is the content of MgO in the slag, wt%; A, B, C, and D are the total contents of CaO, SiO2, Al2O3, and MgO in the steel slag-based solid waste cementitious material, wt%; x is the mass percentage of the steel slag in the steel slag-based solid waste cementitious material, %; y is the mass percentage of the slag in the steel slag-based solid waste cementitious material, %; S4. To make the slag-based solid waste cementitious material have higher early strength and a wider application range, 10 wt% of ordinary Portland cement is incorporated in the formulation, and calculate the mass percentage of the desulfurized gypsum according to 100 wt% content.

8. According to the method for designing the composition of the steel slag-based solid waste cementitious material as claimed in claim 7, characterized in that When the basicity value 1.3 < p ≤ 1.5, the basicity coefficient M = 0.95; When the basicity value 1.5 < p ≤ 1.6, the basicity coefficient M = 1.00; When the basicity value 1.6 < p ≤ 1.7, the basicity coefficient M = 1.05; When the basicity value 1.7 < p ≤ 1.8, the basicity coefficient M = 1.10.

Images