Desulfurized gypsum-based cementing material as well as preparation method and application thereof
By preparing desulfurized gypsum-based cementitious materials, and utilizing the reactivity of gypsum and lime as well as the network structure of early-strength agents, the problems of desulfurized gypsum accumulation pollution and the high cost and insufficient early strength of traditional cementitious materials are solved, providing a low-cost, high-strength building material solution.
Patent Information
- Application Number
- CN202511056890.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2025-11-04
AI Technical Summary
In existing technologies, the stockpiling and disposal of desulfurized gypsum occupies land and pollutes the environment. Traditional cementitious materials are costly and lack early strength, which cannot meet the requirements of high-demand application scenarios.
Desulfurized gypsum-based cementitious materials are prepared by mixing and stirring raw materials such as desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime, and early strength agent. The ettringite in the gypsum fills the voids in the cement particles, the lime provides an alkaline environment to promote the reaction, and the early strength agent forms a spatial cross-network structure to improve early strength.
It has achieved a low-cost, high-early-strength cementitious material that is suitable for engineering construction, meets the needs of large-scale preparation, and has good engineering quality control.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of solid waste materials technology, and in particular to a desulfurized gypsum-based cementitious material, its preparation method, and its application. Background Technology
[0002] Desulfurized gypsum is a byproduct of the process of desulfurizing and purifying sulfur dioxide in flue gas produced by the combustion of sulfur-containing fuels. With the rapid advancement of the technology, the production of desulfurized gypsum is increasing. Existing production enterprises stockpile desulfurized gypsum. Although this method is simple, it occupies a large area of land and pollutes the soil and water sources at the stockpile site, seriously affecting the surrounding environment.
[0003] Cementitious materials are the most crucial materials in backfilling technology; changes in cementitious materials inevitably lead to changes in backfilling techniques. Traditional cementitious materials are ordinary Portland cement. While cement offers good performance, it is very expensive, and cement-based cementitious materials lack sufficient early strength, requiring long curing periods to reach usable standards, thus failing to meet the demands of some high-requirement applications. Therefore, developing a cementitious material with desulfurized gypsum as the main raw material, offering high early strength and low cost, has become an urgent problem to solve. Summary of the Invention
[0004] The purpose of this invention is to overcome the problems in the prior art and provide a desulfurized gypsum-based cementitious material, its preparation method, and its application.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a desulfurized gypsum-based cementitious material, comprising the following raw materials in parts by weight:
[0007] 70-80 parts desulfurized gypsum, 15-30 parts steel slag, 60-90 parts aggregate, 30-40 parts cement, 20-35 parts fly ash, 5-8 parts lime, 3-4 parts water-reducing agent, 1-1.5 parts early strength agent, and 75-80 parts water.
[0008] Preferably, the desulfurized gypsum has a moisture content of ≤1% and a particle size of 0.04 to 0.08 mm.
[0009] Preferably, the particle size of the steel slag is ≤15mm;
[0010] The aggregate particle size is ≤1cm; the density of fly ash is 2~2.3g / cm³. 3 .
[0011] Preferably, the specific surface area of the lime is 300-400 m². 2 / kg;
[0012] The water-reducing agent is a polycarboxylate water-reducing agent and / or a naphthalene-based water-reducing agent.
[0013] Preferably, the method for preparing the early strength agent includes the following steps:
[0014] (1) Carbodiimide and N-hydroxysuccinimide were added sequentially to a polycarboxylated cage-type silsesquioxane solution to obtain an activated system;
[0015] (2) The attapulgite solution and the activation system are mixed and reacted to obtain the early strength agent.
[0016] As a preferred embodiment, in step (1), the mass-to-volume ratio of polycarboxylated cage-type silsesquioxane to N,N-dimethylformamide in the polycarboxylated cage-type silsesquioxane solution is 5-10 g: 50-60 mL.
[0017] The mass ratio of carbodiimide to polycarboxylated cage-type silsesquioxane is 2–3:5–10;
[0018] The mass ratio of N-hydroxysuccinimide to polycarboxylated cage-type silsesquioxane is 1.4–1.5:5–10;
[0019] The stirring temperature after adding carbodiimide is 1–5°C, and the stirring time is 10–15 min.
[0020] The stirring temperature after adding N-hydroxysuccinimide is 20-30℃, and the stirring time is 20-40 min.
[0021] As a preferred embodiment, in step (2) the mass-to-volume ratio of attapulgite to N,N-dimethylformamide in the attapulgite solution is 10-20 g: 200-300 mL.
[0022] The mass ratio of attapulgite to polycarboxylated cage-type silsesquioxane is 10–20:5–10;
[0023] The reaction in step (2) is carried out at a temperature of 50–70°C for 10–14 hours, with a pH of 5–6 and a stirring speed of 700–800 rpm.
[0024] The present invention also provides a method for preparing the desulfurized gypsum-based cementitious material, comprising the following steps:
[0025] (a) A mixture of desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime and early strength agent is prepared to obtain a mixed dry material;
[0026] (b) Mix the dry materials, water-reducing agent and the first portion of water to obtain a wet mix;
[0027] (c) The wet mixture and the remaining water are mixed to obtain the desulfurized gypsum-based cementitious material.
[0028] Preferably, the mixing speed in step (a) is 100-200 rpm and the time is 1-2 min;
[0029] In step (b), the mass of the first portion of water is 60-70% of the total mass of water.
[0030] Preferably, the stirring speed in step (b) is 100-200 rpm and the stirring time is 1-2 min;
[0031] The mixing speed in step (c) is 400-500 rpm and the time is 2-4 min.
[0032] The present invention also provides the application of the desulfurized gypsum-based cementitious material in engineering construction.
[0033] This invention provides a desulfurized gypsum-based cementitious material, comprising the following raw materials in parts by weight: 70-80 parts desulfurized gypsum, 15-30 parts steel slag, 60-90 parts aggregate, 30-40 parts cement, 20-35 parts fly ash, 5-8 parts lime, 3-4 parts water-reducing agent, 1-1.5 parts early-strength agent, and 75-80 parts water. In this invention, desulfurized gypsum is used as the main material to replace part of the cement. The ettringite in the desulfurized gypsum fills the voids between cement particles, thereby improving the strength of the cementitious material. Furthermore, lime is used to provide an alkaline environment, causing the desulfurized gypsum to release sulfate and calcium ions. The sulfate ions combine with the alumina and calcium ions in the fly ash to form ettringite, which fills the pores between materials, improving density and early strength. The calcium ions provided by the desulfurized gypsum react with the silica in the fly ash to form calcium silicate gel, further improving the strength of the cementitious material. The present invention also provides an early strength agent, which grafts polycarboxylated cage-type silsesquioxanes onto the hydroxyl groups on the surface of attapulgite to form a spatially intersecting network structure. This structure is added to the cementitious material as a nucleation site to promote the rapid deposition of hydration products, thereby improving early strength.
[0034] The preparation method of the cementitious material of the present invention is as follows: Desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime, and an early-strength agent are mixed to obtain a dry mixture; the dry mixture, a water-reducing agent, and a first portion of water are stirred to obtain a wet mixture; the wet mixture and the remaining water are mixed to obtain the desulfurized gypsum-based cementitious material. The method provided by the present invention is simple, has low process requirements, and can achieve large-scale preparation, meeting the requirements for large quantities. Detailed Implementation
[0035] This invention provides a desulfurized gypsum-based cementitious material, comprising the following raw materials in parts by weight:
[0036] 70-80 parts desulfurized gypsum, 15-30 parts steel slag, 60-90 parts aggregate, 30-40 parts cement, 20-35 parts fly ash, 5-8 parts lime, 3-4 parts water-reducing agent, 1-1.5 parts early strength agent, and 75-80 parts water.
[0037] In this invention, the desulfurized gypsum is preferably 71 to 79 parts by mass, more preferably 72 to 78 parts by mass, and even more preferably 74 to 76 parts by mass.
[0038] In this invention, the preferred mass fraction of the steel slag is 16-29 parts, more preferably 20-25 parts, and even more preferably 22-23 parts.
[0039] In this invention, the mass fraction of the aggregate is preferably 65-85 parts, more preferably 70-80 parts, and even more preferably 74-76 parts.
[0040] In this invention, the aggregate is manufactured sand; the steel slag and aggregate achieve particle size distribution, which can improve the strength of the material.
[0041] In this invention, the cement is preferably 31 to 39 parts by mass, more preferably 32 to 38 parts by mass, and even more preferably 34 to 36 parts by mass.
[0042] In this invention, the mass fraction of the fly ash is preferably 21 to 34 parts, more preferably 25 to 30 parts, and even more preferably 26 to 27 parts.
[0043] In this invention, the mass fraction of the lime is preferably 5.5 to 7.5 parts, more preferably 6 to 7 parts, and even more preferably 6.4 to 6.5 parts.
[0044] In this invention, the water-reducing agent is preferably 3.1 to 3.9 parts by mass, more preferably 3.2 to 3.8 parts by mass, and even more preferably 3.4 to 3.6 parts by mass.
[0045] In this invention, the mass fraction of the early strength agent is preferably 1.1 to 1.4 parts, more preferably 1.2 to 1.3 parts, and even more preferably 1.24 to 1.26 parts.
[0046] In this invention, the water is preferably 76 to 79 parts by mass, more preferably 77 to 78 parts by mass, and even more preferably 77.4 to 77.6 parts by mass.
[0047] In this invention, the moisture content of the desulfurized gypsum is preferably ≤1%, more preferably ≤0.8%, and even more preferably ≤0.5%; the particle size is preferably 0.04-0.08 mm, more preferably 0.05-0.07 mm, and even more preferably 0.055-0.06 mm.
[0048] In this invention, the particle size of the steel slag is preferably ≤15mm, more preferably ≤10mm, and even more preferably ≤5mm.
[0049] In this invention, the aggregate particle size is preferably ≤1cm, more preferably ≤0.8cm, and even more preferably ≤0.5cm; the fly ash density is preferably 2-2.3g / cm³. 3 More preferably, it is 2.1–2.2 g / cm³. 3 More preferably, it is 2.15–2.18 g / cm³. 3 .
[0050] In this invention, the specific surface area of the lime is preferably 300-400 m². 2 / kg, more preferably 320-380m 2 / kg, more preferably 340-360m 2 / kg.
[0051] In this invention, the water-reducing agent is a polycarboxylate water-reducing agent and / or a naphthalene-based water-reducing agent.
[0052] In this invention, the preparation method of the early strength agent includes the following steps:
[0053] (1) Carbodiimide and N-hydroxysuccinimide were added sequentially to a polycarboxylated cage-type silsesquioxane solution to obtain an activated system;
[0054] (2) The attapulgite solution and the activation system are mixed and reacted to obtain the early strength agent.
[0055] In this invention, in step (1) the mass-volume ratio of polycarboxylated cage-type silsesquioxane to N,N-dimethylformamide in the polycarboxylated cage-type silsesquioxane solution is preferably 5-10 g: 50-60 mL, more preferably 6-9 g: 52-58 mL, and even more preferably 7-8 g: 54-56 mL.
[0056] In this invention, the mass ratio of carbodiimide to polycarboxylated cage-type silsesquioxane is preferably 2-3:5-10, more preferably 2.2-2.8:6-9, and even more preferably 2.4-2.6:7-8.
[0057] In this invention, the mass ratio of N-hydroxysuccinimide to polycarboxylated cage-type silsesquioxane is preferably 1.4-1.5:5-10, more preferably 1.42-1.48:6-9, and even more preferably 1.44-1.46:7-8.
[0058] In this invention, the stirring temperature after adding carbodiimide is preferably 1-5°C, more preferably 2-4°C, and even more preferably 2.5-3°C; the stirring time is preferably 10-15 min, more preferably 11-14 min, and even more preferably 12-13 min.
[0059] In this invention, the stirring temperature after adding N-hydroxysuccinimide is preferably 20-30°C, more preferably 22-28°C, and even more preferably 24-26°C; the stirring time is preferably 20-40 min, more preferably 25-35 min, and even more preferably 26-32 min.
[0060] In this invention, the mass-to-volume ratio of attapulgite and N,N-dimethylformamide in the attapulgite solution in step (2) is preferably 10-20g:200-300mL, more preferably 12-18g:220-280mL, and even more preferably 14-16g:240-260mL.
[0061] In this invention, the mass ratio of attapulgite to polycarboxylated cage-type silsesquioxane is preferably 10-20:5-10, more preferably 12-18:6-9, and even more preferably 14-16:7-8.
[0062] In this invention, an attapulgite solution and an activation system are mixed in a protective atmosphere, wherein the protective atmosphere is nitrogen, argon, or helium.
[0063] In this invention, the reaction temperature in step (2) is preferably 50-70°C, more preferably 55-65°C, and even more preferably 58-62°C; the reaction time is preferably 10-14 h, more preferably 11-13 h, and even more preferably 12-12.5 h; the pH is preferably 5-6, more preferably 5.2-5.8, and even more preferably 5.4-5.6; the pH is adjusted using 0.1M hydrochloric acid; the stirring speed is preferably 700-800 rpm, more preferably 720-780 rpm, and even more preferably 740-760 rpm.
[0064] In this invention, after the reaction in step (2) is completed, the agent is centrifuged, washed with water, and vacuum dried to obtain an early strength agent.
[0065] The present invention also provides a method for preparing the desulfurized gypsum-based cementitious material, comprising the following steps:
[0066] (a) A mixture of desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime and early strength agent is prepared to obtain a mixed dry material;
[0067] (b) Mix the dry materials, water-reducing agent and the first portion of water to obtain a wet mix;
[0068] (c) The wet mixture and the remaining water are mixed to obtain the desulfurized gypsum-based cementitious material.
[0069] In this invention, the mixing speed in step (a) is preferably 100-200 rpm, more preferably 120-180 rpm, and even more preferably 140-160 rpm; the mixing time is preferably 1-2 min, more preferably 1.2-1.8 min, and even more preferably 1.4-1.6 min.
[0070] In this invention, the mass of the first portion of water in step (b) is preferably 60-70% of the total mass of water, more preferably 62-68%, and even more preferably 64-66%.
[0071] In this invention, the stirring speed in step (b) is preferably 100-200 rpm, more preferably 120-180 rpm, and even more preferably 140-160 rpm; the stirring time is preferably 1-2 min, more preferably 1.2-1.8 min, and even more preferably 1.4-1.6 min.
[0072] In this invention, the mixing speed in step (c) is preferably 400-500 rpm, more preferably 420-480 rpm, and even more preferably 440-460 rpm; the mixing time is preferably 2-4 min, more preferably 2.5-3.5 min, and even more preferably 2.8-3.2 min.
[0073] The present invention also provides the application of the desulfurized gypsum-based cementitious material in engineering construction.
[0074] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0075] Example 1
[0076] 8g of polycarboxylated cage-type silsesquioxane and 55mL of N,N-dimethylformamide were mixed and stirred to prepare a polycarboxylated cage-type silsesquioxane solution. 2g of carbodiimide was added to the above solution and stirred at 1℃ for 10min. Then, 1.4g of N-hydroxysuccinimide was added and the temperature was raised to 25℃ and stirred for 30min to obtain an activation system. 15g of attapulgite and 250mL of N,N-dimethylformamide were mixed to prepare an attapulgite solution. Under a nitrogen atmosphere, the activation system and the attapulgite solution were mixed, and the stirring speed was maintained at 750rpm. The pH was adjusted to 5.5 using 0.1M hydrochloric acid, and the reaction was carried out at 60℃ for 12h. After the reaction, the mixture was centrifuged, washed with water, and vacuum dried sequentially to obtain an early strength agent.
[0077] Take 75 parts desulfurized gypsum, 20 parts steel slag, 70 parts aggregate (manufactured sand), 35 parts silicate cement, 25 parts fly ash, 7 parts lime, 3.5 parts polycarboxylate superplasticizer, 1 part of the prepared early strength agent and 77 parts water;
[0078] The desulfurized gypsum has a moisture content of 0.8% and a particle size of 0.05 mm; the steel slag has a particle size of 10 mm; the aggregate has a particle size of 0.8 cm; and the fly ash has a density of 2.1 g / cm³. 3 The specific surface area of lime is 340 m². 2 / kg.
[0079] Desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime and early strength agent are mixed at 160 rpm for 1.5 min; then water-reducing agent and 65% water are added and mixed at 150 rpm for 2 min; then the remaining water is added and mixed at 450 rpm for 3 min to obtain desulfurized gypsum-based cementitious material.
[0080] Example 2
[0081] A polycarboxylated cage-type silsesquioxane solution was prepared by mixing and stirring 5g of polycarboxylated cage-type silsesquioxane and 58mL of N,N-dimethylformamide. 3g of carbodiimide was added to the solution and stirred at 1℃ for 15min. Then, 1.5g of N-hydroxysuccinimide was added, and the temperature was raised to 25℃ and stirred for 40min to obtain the activated system. An attapulgite solution was prepared by mixing 20g of attapulgite and 300mL of N,N-dimethylformamide. Under a nitrogen atmosphere, the activated system and the attapulgite solution were mixed, and the stirring speed was maintained at 800rpm. The pH was adjusted to 5 using 0.1M hydrochloric acid, and the reaction was carried out at 70℃ for 14h. After the reaction, the mixture was sequentially centrifuged, washed with water, and vacuum dried to obtain the early strength agent.
[0082] Take 71 parts of desulfurized gypsum, 27 parts of steel slag, 88 parts of aggregate (manufactured sand), 34 parts of silicate cement, 31 parts of fly ash, 6 parts of lime, 4 parts of naphthalene-based water-reducing agent, 1.1 parts of the prepared early strength agent and 80 parts of water;
[0083] The desulfurized gypsum has a moisture content of 1% and a particle size of 0.04 mm; the steel slag has a particle size of 12 mm; the aggregate has a particle size of 0.5 cm; and the fly ash has a density of 2.3 g / cm³. 3 The specific surface area of lime is 360 m². 2 / kg.
[0084] Desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime and early strength agent are mixed at 180 rpm for 1 min; then water-reducing agent and 70% water are added and mixed at 200 rpm for 2 min; then the remaining water is added and mixed at 500 rpm for 4 min to obtain desulfurized gypsum-based cementitious material.
[0085] Example 3
[0086] A polycarboxylated cage-type silsesquioxane solution was prepared by mixing and stirring 9g of polycarboxylated cage-type silsesquioxane and 51mL of N,N-dimethylformamide. 2.3g of carbodiimide was added to the solution and stirred at 4℃ for 10min. Then, 1.4g of N-hydroxysuccinimide was added, and the temperature was raised to 30℃ and stirred for 30min to obtain the activated system. An attapulgite solution was prepared by mixing 13g of attapulgite and 260mL of N,N-dimethylformamide. The activated system and the attapulgite solution were mixed under a nitrogen atmosphere, maintaining a stirring speed of 740rpm. The pH was adjusted to 5.8 using 0.1M hydrochloric acid, and the reaction was carried out at 55℃ for 11h. After the reaction, the mixture was sequentially centrifuged, washed with water, and vacuum dried to obtain the early strength agent.
[0087] Take 78 parts of desulfurized gypsum, 16 parts of steel slag, 90 parts of aggregate (manufactured sand), 30 parts of silicate cement, 34 parts of fly ash, 8 parts of lime, 3.2 parts of naphthalene-based water-reducing agent, 1.4 parts of the prepared early strength agent and 76 parts of water;
[0088] The desulfurized gypsum has a moisture content of 0.8% and a particle size of 0.08 mm; the steel slag has a particle size of 14 mm; the aggregate has a particle size of 0.7 cm; and the fly ash has a density of 2.1 g / cm³. 3 The specific surface area of lime is 330 m². 2 / kg.
[0089] Desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime and early strength agent are mixed at 110 rpm for 2 min; then water-reducing agent and 65% water are added and mixed at 180 rpm for 2 min; then the remaining water is added and mixed at 450 rpm for 2.5 min to obtain desulfurized gypsum-based cementitious material.
[0090] The desulfurized gypsum-based cementitious material prepared above was subjected to performance tests. The setting time was tested according to method T0505 in the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420-2020). The compressive strength was tested according to method T0506 in the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420-2020). The results are recorded in Table 1.
[0091] Table 1 Performance Test Results
[0092]
[0093] As can be seen from the results in Table 1, the desulfurized gypsum-based cementitious material provided by this invention can achieve a compressive strength of 34.6 MPa at 3 days, demonstrating outstanding early strength performance; it can achieve a compressive strength of 56.3 MPa at 28 days, demonstrating excellent performance; and its initial setting time reaches 382 minutes, providing a long allowable construction time, which is beneficial for project quality control.
[0094] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A desulfurized gypsum-based cementitious material, characterized in that, Raw materials comprising the following parts by weight: 70-80 parts desulfurized gypsum, 15-30 parts steel slag, 60-90 parts aggregate, 30-40 parts cement, 20-35 parts fly ash, 5-8 parts lime, 3-4 parts water-reducing agent, 1-1.5 parts early strength agent, and 75-80 parts water.
2. The desulfurized gypsum-based cementitious material as described in claim 1, characterized in that, The desulfurized gypsum has a moisture content of ≤1% and a particle size of 0.04~0.08mm.
3. The desulfurized gypsum-based cementitious material as described in claim 2, characterized in that, The particle size of the steel slag is ≤15mm; The aggregate particle size is ≤1cm; the density of fly ash is 2~2.3g / cm³. 3 .
4. The desulfurized gypsum-based cementitious material as described in claim 3, characterized in that, The specific surface area of the lime is 300-400 m². 2 / kg; The water-reducing agent is a polycarboxylate water-reducing agent and / or a naphthalene-based water-reducing agent.
5. The desulfurized gypsum-based cementitious material as described in claim 4, characterized in that, The preparation method of the early strength agent includes the following steps: (1) An activation system was obtained by sequentially adding carbodiimide and N-hydroxysuccinimide to a polycarboxylated cage-type silsesquioxane solution; (2) The attapulgite solution and the activation system are mixed and reacted to obtain the early strength agent.
6. The desulfurized gypsum-based cementitious material as described in claim 5, characterized in that, In step (1), the mass-to-volume ratio of polycarboxylated cage-type silsesquioxane to N,N-dimethylformamide in the polycarboxylated cage-type silsesquioxane solution is 5-10 g: 50-60 mL. The mass ratio of carbodiimide to polycarboxylated cage-type silsesquioxane is 2–3:5–10; The mass ratio of N-hydroxysuccinimide to polycarboxylated cage-type silsesquioxane is 1.4–1.5:5–10; The stirring temperature after adding carbodiimide is 1–5°C, and the stirring time is 10–15 min. The stirring temperature after adding N-hydroxysuccinimide is 20-30℃, and the stirring time is 20-40 min.
7. The desulfurized gypsum-based cementitious material as described in claim 6, characterized in that, In step (2), the mass-to-volume ratio of attapulgite to N,N-dimethylformamide in the attapulgite solution is 10-20 g: 200-300 mL. The mass ratio of attapulgite to polycarboxylated cage-type silsesquioxane is 10–20:5–10; The reaction in step (2) is carried out at a temperature of 50–70°C for 10–14 hours, with a pH of 5–6 and a stirring speed of 700–800 rpm.
8. A method for preparing the desulfurized gypsum-based cementitious material according to any one of claims 1 to 7, characterized in that, Includes the following steps: (a) A mixture of desulfurized gypsum, steel slag, aggregate, cement, fly ash, lime and early strength agent is prepared to obtain a mixed dry material; (b) Mix the dry materials, water-reducing agent and the first portion of water to obtain a wet mix; (c) The wet mixture and the remaining water are mixed to obtain the desulfurized gypsum-based cementitious material.
9. The preparation method of the desulfurized gypsum-based cementitious material as described in claim 8, characterized in that, The mixing speed in step (a) is 100-200 rpm, and the time is 1-2 min; In step (b), the mass of the first portion of water is 60-70% of the total mass of water; The stirring speed in step (b) is 100-200 rpm, and the stirring time is 1-2 min; The mixing speed in step (c) is 400-500 rpm and the time is 2-4 min.
10. The application of the desulfurized gypsum-based cementitious material according to any one of claims 1 to 7 in engineering construction.