An early-strength and crack-resistant solid waste-based belite cementitious material and its preparation method

Abstract

The present invention relates to the technical field of cement clinker preparation, and specifically discloses an early-strength and crack-resistant solid waste-based belite cementitious material and a preparation method thereof. The cementitious material comprises the following components: C2S 20-35 wt.% 、C4A3$ 20~40 wt .%, CaSO4 6~20 wt. %, C5S2$ 3~15 wt. %, C6AF2 1~3 wt. %, C 11 A7CaF2 3~15 wt. The preparation method comprises the following steps: mixing a calcium raw material, an aluminum raw material, an iron raw material, and fluorgypsum to form a raw material, and then calcining the raw material. After completion, the calcined product is rapidly cooled to obtain the cementitious material. The cementitious material of the present invention not only significantly improves its early strength and crack resistance, but also reduces the calcination temperature, thereby reducing energy consumption and carbon emissions.

Description

Technical Field

[0001] The invention relates to the technical field of cement clinker preparation, and in particular to an early-strength and crack-resistant solid waste-based belite cementitious material and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Ordinary Portland cement is currently the most widely used cement binder. It is obtained by calcining mineral raw materials at high temperatures. The main components of ordinary Portland cement include tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF). The formation temperature of tricalcium silicate (C3S) is as high as 1450°C, which results in high energy consumption and high carbon emissions in the production of ordinary Portland cement. Currently, my country's cement industry is entering a new stage of development. Green, low-carbon, and circular production are not only the requirements of the times, but also the only way for the cement industry to achieve sustainable development. Therefore, exploring low-energy cement clinker preparation technologies is of great practical significance.

[0004] Compared to tricalcium silicate, the formation temperature of dicalcium silicate is approximately 200°C lower. However, dicalcium silicate has low gelling activity and slow hydration reaction, resulting in serious deficiencies in the early strength development and crack resistance of cement clinker composed primarily of dicalcium silicate. Therefore, exploring the preparation technology of early-strength, crack-resistant cement clinker composed primarily of dicalcium silicate is an effective way to achieve green, low-carbon, low-energy, and sustainable development in the cement industry. Summary of the Invention

[0005] The present invention provides an early-strength, crack-resistant solid waste-based belite cementitious material and a preparation method thereof. This cementitious material not only significantly improves its early strength and crack resistance but also reduces the calcination temperature, thereby reducing energy consumption and carbon emissions. Specifically, the technical solution of the present invention is as follows.

[0006] First, the present invention discloses an early strength and crack resistance solid waste based belite cementitious material, comprising the following components: C2S 20~35 wt. %, C4A3$ 20~40 wt .%, CaSO46~20 wt. %, C5S2$ 3~15 wt. %,C6AF21~3 wt. %, C 11 A7CaF23~15 wt. %.

[0007] Furthermore, the cementitious material also includes gypsum. Optionally, the amount of gypsum added is 3 to 20% of the mass of the cementitious material. wt .%.

[0008] Furthermore, the gypsum includes at least one of chemically pure gypsum and solid waste gypsum (such as desulfurized gypsum, phosphogypsum, fluorinated gypsum, titanium gypsum, etc.).

[0009] The present invention also discloses a method for preparing an early-strength, crack-resistant solid waste-based belite cementitious material, comprising the steps of: uniformly mixing a calcium raw material, an aluminum raw material, an iron raw material, and fluorgypsum to form a raw meal, followed by calcining the raw meal. After calcination, the calcined product is rapidly cooled to obtain the cementitious material.

[0010] Furthermore, the proportions of the raw materials in the raw meal are as follows: 40.6-52.3 parts by weight of calcium raw material, 21.3-34.0 parts by weight of aluminum raw material, 1.2-10.1 parts by weight of iron raw material, and 14.4-23.3 parts by weight of fluorgypsum.

[0011] Furthermore, the calcium raw material includes at least one of limestone, carbide slag, quicklime, etc.

[0012] Furthermore, the aluminum raw material includes at least one of bauxite, high-aluminum fly ash, aluminum slag, etc. The high-aluminum fly ash refers to a material with an alumina content greater than 38 wt. % fly ash.

[0013] Furthermore, the iron raw material includes at least one of iron tailings, red mud, etc.

[0014] Furthermore, the calcination treatment is carried out at a temperature of 1150-1250° C. and for a time of 20-35 minutes.

[0015] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0016] The component system of the Belite cementitious material of the present invention contains a large amount of C2S and C4A3$. The C4A3$ has good early hydration ability, so that the cementitious material can have good early strength, overcoming the problem of insufficient early strength development and crack resistance caused by the low gelling activity and slow hydration reaction of C2S. At the same time, the C5S2$ and C6AF2 have the characteristics of synergistic hydration and improved crack resistance. This is because the hydration product (A, F) H3 formed by the hydration of the C6AF2 mineral with a faster reaction rate can promote the hydration rate of the C5S2$ and form an expansive hydration product, thereby curbing the microcracks caused by shrinkage of the cementitious material during the hydration and hardening process, thereby improving the crack resistance of the cementitious material of the present invention and improving the mechanical properties. In addition, when preparing the Belite cementitious material, the present invention found that the fluorine ions provided by fluorgypsum promote the decomposition of part of the C4A3$ to form C 11 A7CaF2 significantly improves the early strength of the cementitious material of the present invention, and effectively reduces the calcination temperature, thereby helping to reduce the energy consumption and carbon emissions of the cementitious material required for firing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 This is a sample of the belite cementitious material prepared in Example 1 below.

[0019] Figure 2 The following is the XRD pattern of the belite gelling material prepared in Example 1.

[0020] Figure 3 This is a sample of the belite cementitious material prepared in the following Example 2.

[0021] Figure 4 The following is the XRD pattern of the belite gelled material prepared in Example 2.

[0022] Figure 5 This is a sample of the belite cementitious material prepared in Example 3 below.

[0023] Figure 6 The following is the XRD pattern of the belite gelled material prepared in Example 3. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0025] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. The reagents and raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in the present invention are used in accordance with conventional methods in the art or in accordance with the product instructions.

[0026] In addition, any methods and materials similar or equivalent to those described herein can be applied to the method of the present invention. The technical solution of the present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0027] Example 1:

[0028] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0029] (1) Weigh the following raw materials: 50.5 parts by weight of limestone, 28.3 parts by weight of bauxite, 4.1 parts by weight of iron ore tailings, and 17.1 parts by weight of fluorspar.

[0030] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0031] (3) The raw cake is heated to 1200°C at a heating rate of 10°C / min and calcined for 30 minutes. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material, such as Figure 1 shown.

[0032] (4) The cementitious material is mixed with desulfurized gypsum and ground to obtain Belite cementitious material, wherein the desulfurized gypsum accounts for 15% of the mass of the cementitious material.

[0033] The physical phase of the cementitious material prepared in step (3) of this embodiment was tested and analyzed by X-ray diffraction (XRD). The results are as follows: Figure 2 After calculation, the content of each mineral phase in the cementitious material is as follows: C2S31.56 wt. %,C4A3$ 35.18 wt .%,CaSO414.29 wt. %,C5S2$ 7.42 wt. %,C6AF21.86 wt. %, C 11 A7CaF28.03 wt. %, and the remainder are inevitable impurities.

[0034] Performance test: (1) The early (2h) compressive strength of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 18.5 MPa. (2) The 7-day mortar linear expansion rate of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 7.9×10 -4 .

[0035] Example 2:

[0036] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0037] (1) Weigh the following raw materials: 45.3 parts by weight of limestone, 32.1 parts by weight of bauxite, 2.2 parts by weight of iron ore tailings, and 20.4 parts by weight of fluorgypsum.

[0038] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0039] (3) The raw cake is heated to 1180°C at a heating rate of 10°C / min and calcined for 35 minutes. After completion, the calcined product is quenched to room temperature by blowing air to obtain a gelled material, such as Figure 3 shown.

[0040] (4) The cementitious material is mixed with desulfurized gypsum and ground to obtain Belite cementitious material, wherein the desulfurized gypsum accounts for 12% of the mass of the cementitious material.

[0041] The physical phase of the gelling material prepared in step (3) of this embodiment was tested and analyzed by X-ray diffraction (XRD). The results are as follows: Figure 4 After calculation, the content of each mineral phase in the cementitious material is as follows: C2S 20.04 wt. %,C4A3$ 37.23 wt .%,CaSO416.48 wt. %,C5S2$ 11.52 wt. %,C6AF22.98 wt. %, C 11 A7CaF28.87 wt. %, and the remainder are inevitable impurities.

[0042] Performance test: (1) The early (2h) compressive strength of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 23.6MPa. (2) The 7-day mortar linear expansion rate of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 9.2×10 -4 .

[0043] Example 3:

[0044] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0045] (1) Weigh the following raw materials: 40.6 parts by weight of quicklime, 34.0 parts by weight of aluminum slag, 10.1 parts by weight of iron tailings, and 15.3 parts by weight of fluorgypsum.

[0046] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0047] (3) The raw cake is heated to 1250°C at a heating rate of 10°C / min and calcined for 20 minutes. After completion, the calcined product is quenched to room temperature by blowing air to obtain a gelled material, such as Figure 5 shown.

[0048] (4) The cementitious material is mixed with desulfurized gypsum and ground to obtain Belite cementitious material, wherein the desulfurized gypsum accounts for 12% of the mass of the cementitious material.

[0049] The physical phase of the gelling material prepared in step (3) of this embodiment was tested and analyzed by X-ray diffraction (XRD). The results are as follows: Figure 6 After calculation, the content of each mineral phase in the cementitious material is as follows: C2S 26.17 wt. %,C4A3$ 40.06 wt .%,CaSO48.22 wt. %,C5S2$ 14.97 wt. %,C6AF21.02 wt. %, C 11 A7CaF27.31 wt. %, and the remainder are inevitable impurities.

[0050] Performance test: (1) The early (2h) compressive strength of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 20.8 MPa. (2) The 7-day mortar linear expansion rate of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 6.7×10 -4 .

[0051] Example 4:

[0052] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0053] (1) Weigh the following raw materials: 51.1 parts by weight of limestone, high-aluminum fly ash (aluminum oxide content of 38.09 wt. %), 26.4 parts by weight, 1.1 parts by weight of iron tailings, and 21.4 parts by weight of fluorgypsum.

[0054] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0055] (3) The raw cake is heated to 1220°C at a heating rate of 10°C / min and calcined for 30 minutes. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material.

[0056] (4) The cementitious material is mixed with phosphogypsum and ground to obtain a Belite cementitious material, wherein the phosphogypsum accounts for 3% of the mass of the cementitious material.

[0057] The phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of each mineral phase in the cementitious material are as follows: C2S 35.05 wt. %,C4A3$ 22.71 wt .%,CaSO419.94 wt. %,C5S2$ 3.07 wt. %,C6AF22.63 wt. %, C 11 A7CaF215.04 wt. %, and the remainder are inevitable impurities.

[0058] Performance test: (1) The early (2h) compressive strength of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 24.9 MPa. (2) The 7-day mortar linear expansion rate of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 5.5×10 -4 .

[0059] Example 5:

[0060] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0061] (1) Weigh the following raw materials in the following proportions: 50.3 parts by weight of limestone, 21.2 parts by weight of bauxite, 5.3 parts by weight of Bayer red mud, and 23.2 parts by weight of fluorgypsum.

[0062] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0063] (3) The raw cake is heated to 1200°C at a heating rate of 10°C / min and calcined for 35 minutes. After completion, the calcined product is quenched to room temperature by blowing air to obtain a gelled material.

[0064] (4) The gelling material is mixed with fluorgypsum and ground to obtain a Belite gelling material, wherein the fluorgypsum accounts for 18% of the mass of the gelling material.

[0065] The phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of each mineral phase in the cementitious material are as follows: C2S 32.84 wt. %,C4A3$ 27.32 wt .%,CaSO418.95 wt. %,C5S2$ 13.12 wt. %,C6AF22.77 wt. %, C 11 A7CaF23.01 wt. %, and the remainder are inevitable impurities.

[0066] Performance test: (1) The early (2h) compressive strength of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 13.2 MPa. (2) The 7-day mortar linear expansion rate of the belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 5.2×10 -4 .

[0067] Example 6:

[0068] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0069] (1) Weigh the following raw materials: 52.1 parts by weight of limestone, 24.5 parts by weight of bauxite, 4.2 parts by weight of Bayer red mud, and 19.2 parts by weight of fluorgypsum.

[0070] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0071] (3) The raw cake is heated to 1180°C at a heating rate of 10°C / min and calcined for 35 minutes. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material.

[0072] (4) The gelling material is mixed with fluorinated gypsum and ground to obtain a Belite gelling material, wherein the fluorinated gypsum accounts for 20% of the mass of the gelling material.

[0073] The phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of each mineral phase in the cementitious material are as follows: C2S 33.91 wt. %,C4A3$ 20.08 wt .%,CaSO416.58 wt. %,C5S2$ 10.46 wt. %,C6AF22.69 wt. %, C 11 A7CaF214.27 wt. %, and the remainder are inevitable impurities.

[0074] Performance test: (1) The early (2h) compressive strength of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 19.6 MPa. (2) The 7-day mortar linear expansion rate of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 6.4×10 -4 .

[0075] Example 7:

[0076] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0077] (1) Weigh the following raw materials: 52.3 parts by weight of limestone, 32.1 parts by weight of bauxite, 1.2 parts by weight of Bayer red mud, and 14.4 parts by weight of fluorgypsum.

[0078] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0079] (3) The raw cake is heated to 1160°C at a heating rate of 10°C / min and calcined for 35 minutes. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material.

[0080] (4) The gelling material is mixed with desulfurized gypsum and ground to obtain Belite gelling material, wherein the desulfurized gypsum accounts for 20% of the mass of the gelling material.

[0081] The phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of each mineral phase in the cementitious material are as follows: C2S 30.43 wt. %,C4A3$ 32.79 wt .%,CaSO45.96 wt. %,C5S2$ 12.24 wt. %,C6AF21.36 wt. %, C 11 A7CaF213.75 wt. %, and the remainder are inevitable impurities.

[0082] Performance test: (1) The early (2h) compressive strength of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 22.4 MPa. (2) The 7-day mortar linear expansion rate of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 7.5×10 -4 .

[0083] Example 8:

[0084] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0085] (1) Weigh the following raw materials: 50.5 parts by weight of limestone, 28.3 parts by weight of bauxite, 4.1 parts by weight of iron ore tailings, and 17.1 parts by weight of chemically pure gypsum.

[0086] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0087] (3) The raw cake is heated to 1200°C at a heating rate of 10°C / min and calcined for 30 min. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material.

[0088] (4) The cementitious material is mixed with desulfurized gypsum and ground to obtain a Belite cementitious material, wherein the gypsum accounts for 15% of the mass of the cementitious material.

[0089] The phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of each mineral phase in the cementitious material are as follows: C2S 32.19 wt. %,C4A3$ 43.37 wt .%,CaSO411.17 wt. %,C5S2$ 9.26 wt. %,C6AF22.44 wt. %, and the remainder are inevitable impurities.

[0090] Performance test: (1) The early (2h) compressive strength of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 8.6 MPa. (2) The 7-day mortar linear expansion rate of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 1.3×10 -4 .

[0091] Example 9:

[0092] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0093] (1) Weigh the following raw materials: 45.3 parts by weight of limestone, 32.1 parts by weight of bauxite, 2.2 parts by weight of iron ore tailings, and 20.4 parts by weight of phosphogypsum.

[0094] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0095] (3) The raw cake is heated to 1180°C at a heating rate of 10°C / min and calcined for 35 minutes. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material.

[0096] (4) The cementitious material is mixed with desulfurized gypsum and ground to obtain Belite cementitious material, wherein the desulfurized gypsum accounts for 12% of the mass of the cementitious material.

[0097] The phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of each mineral phase in the cementitious material are as follows: C2S 32.67 wt. %, C4A3$ 34.13 wt .%,CaSO414.85 wt. %,C5S2$ 13.44 wt. %,C6AF22.31 wt. %, and the remainder are inevitable impurities.

[0098] Performance test: (1) The early (2h) compressive strength of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 7.4 MPa. (2) The 7-day mortar linear expansion rate of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 2.1×10 -4 .

[0099] Example 10:

[0100] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0101] (1) Weigh the following raw materials: 37.2 parts by weight of quicklime, 37.1 parts by weight of aluminum slag, 7.4 parts by weight of iron tailings, and 18.3 parts by weight of fluorgypsum.

[0102] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0103] (3) The raw cake is heated to 1250°C at a heating rate of 10°C / min and calcined for 20 min. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material.

[0104] (4) The cementitious material is mixed with desulfurized gypsum and ground to obtain Belite cementitious material, wherein the desulfurized gypsum accounts for 12% of the mass of the cementitious material.

[0105] The physical phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of the mineral phases of the clinker in the cementitious material are as follows: C2S 36.17wt.%, C4A3$ 43.61wt.%, CaSO4 7.01wt.%, C5S2$ 4.89wt.%, C6AF21.56wt.%, C 11 A7CaF2 4.73wt.%, the remainder being inevitable impurities.

[0106] Performance test: (1) The early (2h) compressive strength of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 10.3 MPa. (2) The 7-day mortar linear expansion rate of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 1.9×10 -4 .

[0107] Example 11:

[0108] A method for preparing an early-strength and crack-resistant solid waste-based belite cementitious material comprises the following steps:

[0109] (1) Weigh the following raw materials: 49.2 parts by weight of limestone, high-aluminum fly ash (aluminum oxide content of 38.09 wt. %) 32.4 parts by weight, 18.4 parts by weight of fluorgypsum.

[0110] (2) Grind the above raw materials in a grinder, add water to the obtained mixed powder and stir evenly, then press it into round cakes and dry it to obtain raw cakes.

[0111] (3) The raw cake is heated to 1220°C at a heating rate of 10°C / min and calcined for 30 minutes. After completion, the calcined product is rapidly cooled to room temperature by blowing air to obtain a gelled material.

[0112] (4) The cementitious material is mixed with phosphogypsum and ground to obtain a Belite cementitious material, wherein the phosphogypsum accounts for 3% of the mass of the cementitious material.

[0113] The phases of the cementitious material prepared in step (3) of this embodiment were tested and analyzed by X-ray diffraction (XRD). After calculation, the contents of each mineral phase in the cementitious material are as follows: C2S 38.46 wt. %,C4A3$ 23.04 wt .%,CaSO418.63 wt. %,C5S2$ 2.56 wt. %,C6AF20.97 wt. %, C 11 A7CaF213.35 wt. %, and the remainder are inevitable impurities.

[0114] Performance test: (1) The early (2h) compressive strength of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021), and the result was 11.2 MPa. (2) The 7-day mortar linear expansion rate of the Belite cementitious material prepared in step (4) of this embodiment was tested according to the "Test Method for Cement Mortar Expansion" (GB / T 23439-2017), and the result was 3.3×10 -4 .

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An early-strength and crack-resistant solid waste-based belite cementitious material, characterized in that: Includes the following components: C2S 20~35 wt. %, C4A3$ 20~40 wt .%, CaSO4 6~20 wt. %, C5S2$ 3~15 wt. %, C6AF2 1~3 wt. %, C 11 A7CaF2 3~15 wt. %.

2. The early strength and crack resistance solid waste-based belite cementitious material according to claim 1, characterized in that: The cementitious material also includes externally added gypsum.

3. The early strength and crack resistance solid waste-based belite cementitious material according to claim 2, characterized in that: The amount of gypsum is 3 to 20% of the mass of the cementitious material. wt .%; or, the gypsum includes at least one of chemically pure gypsum and solid waste gypsum.

4. The early strength and crack resistance solid waste-based belite cementitious material according to claim 3, characterized in that: The solid waste gypsum includes at least one of desulfurized gypsum, phosphogypsum, fluorinated gypsum and titanium gypsum.

5. The method for preparing the early-strength and crack-resistant solid waste-based belite cementitious material according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: mixing calcium raw material, aluminum raw material, iron raw material and fluorgypsum to form raw material, and then calcining the raw material; after the calcination, rapidly cooling the calcined product to obtain the gelling material.

6. The method for preparing the early-strength and crack-resistant solid waste-based belite cementitious material according to claim 5, characterized in that: The proportions of the raw materials in the raw meal are as follows: 40.6-52.3 parts by weight of calcium raw material, 21.3-34.0 parts by weight of aluminum raw material, 1.2-10.1 parts by weight of iron raw material, and 14.4-23.3 parts by weight of fluorgypsum.

7. The method for preparing the early-strength and crack-resistant solid waste-based belite cementitious material according to claim 5, characterized in that: The calcium raw material includes at least one of limestone, carbide slag and quicklime.

8. The method for preparing the early-strength and crack-resistant solid waste-based belite cementitious material according to claim 5, characterized in that: The aluminum raw material includes at least one of bauxite, high-aluminum fly ash, and aluminum slag.

9. The method for preparing the early-strength and crack-resistant solid waste-based belite cementitious material according to claim 5, characterized in that: The iron raw material includes at least one of iron tailings and red mud.

10. The method for preparing the early-strength and crack-resistant solid waste-based belite cementitious material according to any one of claims 5 to 9, characterized in that: The calcination temperature is 1150-1250° C. and the calcination time is 20-35 minutes.

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