Mixed powder composition for the preparation of geopolymer cementitious materials, process for the preparation thereof and use thereof
By using a modified coal gasification slag and fly ash and a composite activator of solid water glass and red mud, the problems of large activator dosage, high curing temperature and low production efficiency of geopolymer cementitious materials have been solved. The resulting material has excellent early strength and setting efficiency, and outstanding strength stability and durability, and is suitable for construction, road and water conservancy projects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA ENERGY GRP NINGXIA COAL IND CO LTD
- Filing Date
- 2026-02-11
- Publication Date
- 2026-05-29
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of geopolymer material preparation technology, specifically to a mixed powder composition for preparing geopolymer cementitious materials, its preparation method, and its application. Background Technology
[0002] Geopolymer materials have attracted great attention from the global scientific and industrial communities due to their waste utilization, energy saving, and carbon reduction. Their preparation process is simple and does not require high-temperature calcination, and they have broad application prospects in engineering fields such as construction, roads, and water conservancy.
[0003] Currently, the preparation of geopolymer cementitious materials mainly uses single silica-alumina industrial solid waste (such as low-calcium fly ash and red mud) as the main raw materials. However, when silica-alumina solid waste is used alone, geopolymers often suffer from slow early strength development, excessively long setting time, and high curing temperature requirements. Coal gasification slag, as an industrial solid waste generated during the coal gasification process, has a huge output and high silica-alumina-calcium content. It has a highly active glassy structure and cementitious activity close to that of slag, making it a potential material for preparing geopolymers. However, due to its relatively large initial particle size and numerous internal pores, its use as a raw material for geopolymers alone results in high grinding energy consumption and high water demand.
[0004] While existing technologies have attempted to prepare geopolymers by combining two or more solid wastes, these methods often suffer from problems such as unreasonable raw material ratios, a single activation system, the need for high-temperature curing, and high costs associated with the use of activators. Therefore, developing a method for preparing high-performance, low-cost geopolymer cementitious materials with excellent early strength and setting efficiency, outstanding strength stability and durability, and the ability to be produced at room temperature is of great significance. Summary of the Invention
[0005] The purpose of this invention is to overcome the problems of existing methods for preparing geopolymer cementitious materials, such as large amounts of activator, high curing temperatures, low production efficiency, complex raw material pretreatment, and low early strength, setting efficiency, strength stability, and durability of the prepared geopolymer cementitious materials. This invention provides a mixed powder composition for preparing geopolymer cementitious materials, its preparation method, and its application. This method features small amounts of activator, low curing temperatures, and high production efficiency. Furthermore, the mixed powder composition prepared by this method is a solid, facilitating storage and transportation. In use, it can be directly mixed with water to obtain geopolymer cementitious materials with excellent early strength and setting efficiency, and outstanding strength stability and durability.
[0006] To achieve the above objectives, the present invention provides a method for preparing a mixed powder composition for preparing geopolymer cementitious materials, the method comprising the following steps: (1) Mix and grind coal gasification slag, desulfurization gypsum and mirabilite to obtain modified coal gasification slag; (2) Mix the modified coal gasification slag with fly ash; (3) Solid water glass is mixed with red mud to obtain a composite activator; (4) Mix the composite activator with the mixture obtained in step (2); The mass ratio of the modified coal gasification slag to the fly ash is 0.1-0.8:1.
[0007] Preferably, in step (2), the mass ratio of the modified coal gasification slag to the fly ash is 0.2-0.6:1.
[0008] Preferably, the modified coal gasification slag has a specific surface area ≥ 400 m². 2 / kg, particle size ≤300 mesh.
[0009] Preferably, in step (1), the mass ratio of the coal gasification slag to the desulfurization gypsum is 100:1-5, more preferably 100:1.2-4.
[0010] Preferably, the mass ratio of the coal gasification slag to the sodium sulfate is 100:1-10, more preferably 100:2-8.
[0011] Preferably, in step (3), the mass ratio of the solid water glass to the red mud is 1-10:1.
[0012] Preferably, in step (3), the modulus of the solid water glass is 1-2.
[0013] Preferably, the red mud has a particle size ≤300 mesh.
[0014] Preferably, in step (4), the mass ratio of the composite activator to the mixture obtained in step (2) is 1:5-30.
[0015] A second aspect of the present invention provides a mixed powder composition prepared by the above method.
[0016] A third aspect of the present invention provides a geopolymer cementitious material, which is prepared by mixing the above-mentioned mixed powder composition with water.
[0017] The fourth aspect of this invention provides the application of the above-mentioned geopolymer cementitious materials in the construction of buildings, roads, water conservancy projects, and the production of building materials.
[0018] The method described in this invention first involves mixing and grinding coal gasification slag, desulfurization gypsum, and mirabilite to modify the coal gasification slag, resulting in modified coal gasification slag with higher activity, stronger alkali-activated reaction activity, and optimized pore structure. Simultaneously, the modified coal gasification slag is mixed with fly ash. Through the complementary components of the coal gasification slag and fly ash, the activity of the raw materials is synergistically enhanced, solving the instability problem. Furthermore, solid water glass is mixed with red mud to obtain a solid composite activator, which is then mixed with the modified coal gasification slag and fly ash to obtain a mixed powder composition for preparing geopolymer cementitious materials. This method features low activator dosage, low curing temperature, high production efficiency, and simple raw material pretreatment process. Furthermore, the mixed powder composition prepared by this method for preparing geopolymer cementitious materials is solid, which facilitates storage and transportation. When used, it can be directly mixed with water to obtain geopolymer cementitious materials with excellent early strength and setting efficiency, as well as outstanding strength stability and durability. It has broad application prospects in engineering fields such as construction, roads, and water conservancy. Detailed Implementation
[0019] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.
[0020] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0021] The method for preparing the mixed powder composition for preparing geopolymer cementitious materials according to the present invention includes the following steps: (1) Mix and grind coal gasification slag, desulfurization gypsum and mirabilite to obtain modified coal gasification slag; (2) Mix the modified coal gasification slag with fly ash; (3) Solid water glass is mixed with red mud to obtain a composite activator; (4) Mix the composite activator with the mixture obtained in step (2); The mass ratio of the modified coal gasification slag to the fly ash is 0.1-0.8:1.
[0022] In this invention, there is no special limitation on the source of the coal gasification slag; commonly used gasification slag in this industry can be used. As a specific example, the coal gasification slag can be coal gasification slag from coal gasification power generation enterprises, with a composition of 45-55% SiO2, 20-30% Al2O3, 8-15% CaO, 3-8% Fe2O3, 1-4% MgO, and 2-5% other impurities. These other impurities will not negatively affect the implementation effect of this invention.
[0023] In the method described in this invention, in step (1), the coal gasification slag, desulfurization gypsum, and mirabilite are mixed and ground to reduce the porosity and refine the particle size of the coal gasification slag, thereby modifying the slag to obtain modified coal gasification slag with higher activity, stronger alkali-activated reaction activity, and optimized pore structure. The mixing and grinding process is a conventional method in this field and will not be described in detail here.
[0024] In some embodiments, in step (1), the mass ratio of the coal gasification slag to the desulfurization gypsum is 100:1-5, preferably 100:1.2-4, and more preferably 100:1.5-3. As a specific example, the mass ratio of the coal gasification slag to the desulfurization gypsum can be 100:1.5, 100:2, 100:2.5, or 100:3.
[0025] In some embodiments, in step (1), the mass ratio of the coal gasification slag to the sodium sulfate is 100:1-10, preferably 100:1.5-8, and more preferably 100:2-5. As a specific example, the mass ratio of the coal gasification slag to the sodium sulfate can be 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, or 100:5.
[0026] In some preferred embodiments, in step (1), the specific surface area of the modified coal gasification slag is ≥400 m². 2 / kg, preferably 400-550 m 2 / kg; the particle size of the modified coal gasification slag is ≤300 mesh, preferably 300-500 mesh.
[0027] In some preferred embodiments, in step (2), the mass ratio of the modified coal gasification slag to the fly ash is 0.2-0.6:1, more preferably 0.25-0.5:1. As a specific example, the mass ratio of the modified coal gasification slag to the fly ash can be 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, or 0.5:1.
[0028] In this invention, there is no special limitation on the source of the fly ash; commonly used fly ash in this industry can be used. As a specific example, the fly ash can be fly ash from a thermal power plant, with a composition of 40-50% SiO2, 42-49% Al2O3, 1-5% Fe2O3, 1-3% CaO, 0.5-2% TiO2, 0-1% MgO, and 1-4% other impurities. These other impurities will not negatively affect the implementation effect of this invention.
[0029] In some embodiments, in step (3), the mass ratio of the solid water glass to the red mud is 1-10:1, preferably 2-8:1, and more preferably 3-7:1. As a specific example, the mass ratio of the solid water glass to the red mud can be 3:1, 4:1, 5:1, 6:1, or 7:1.
[0030] In some embodiments, in step (3), the modulus of the solid water glass is 1-2, preferably 1.2-1.5. In this invention, the solid water glass with a modulus of 1.2-1.5 can be obtained by compounding solid water glass with a modulus of 1 and a modulus of 2. This method is a conventional means in the art and will not be described in detail here.
[0031] In some embodiments, in step (3), the red mud is dried and ground red mud. Preferably, the particle size of the red mud is ≤300 mesh, and more preferably 300-500 mesh. The red mud can be industrial solid waste generated during the alumina smelting process of bauxite, and its composition is 15-25% SiO2, 10-20% Al2O3, 30-40% CaO, 15-25% Fe2O3, and 3-8% other impurities. These other impurities will not negatively affect the implementation effect of the present invention.
[0032] In some embodiments, in step (4), the mass ratio of the composite activator to the mixture obtained in step (2) is 1:5-30, preferably 1:7-25, and more preferably 1:9-20. As a specific example, the mass ratio of the composite activator to the mixture obtained in step (2) can be 1:9, 1:10, 1:12, 1:14, 1:15, 1:16, 1:18, or 1:20.
[0033] In the method described in this invention, the modified coal gasification slag and the fly ash have complementary contents. Under the action of the composite activator, the disintegration of the aluminosilicate glass structure in the fly ash can be accelerated, ion reconstruction can be promoted, and a stable three-dimensional network structure in which CASH gel (calcium aluminum silicate hydrate) and NASH gel (sodium aluminum silicate hydrate) coexist can be generated, thereby improving the strength and durability of the geopolymer cementitious material.
[0034] The method described in this invention utilizes the complementary composition of coal gasification slag and fly ash to synergistically enhance the activity of raw materials and solve the problem of instability; and adopts a solid composite activator, which is easy to store and transport, and has the characteristics of small activator dosage, low curing temperature, high production efficiency and simple raw material pretreatment process.
[0035] The present invention also provides a mixed powder composition for preparing geopolymer cementitious materials prepared by the above method. The mixed powder composition is solid, which is convenient for storage and transportation. When used, it can be directly mixed with water to obtain geopolymer cementitious materials with excellent early strength and setting efficiency, and outstanding strength stability and durability. It has broad application prospects in the fields of construction, road and water conservancy engineering.
[0036] The present invention also provides a geopolymer cementitious material, which is prepared by mixing the above-mentioned mixed powder composition with water. This material exhibits excellent early strength and setting efficiency, as well as outstanding strength stability and durability.
[0037] In some embodiments, the preparation method of the geopolymer cementitious material includes: mixing water and the mixed powder composition at a mass ratio of 0.35-0.45:1, and stirring for 3-5 minutes until a uniform slurry is formed; The slurry is then poured into a mold, vibrated to form the material, and cured at 20-25℃ for 7-28 days to obtain the geopolymer cementitious material.
[0038] This invention further provides applications of the aforementioned geopolymer cementitious materials in the construction of buildings, roads, water conservancy projects, and the production of building materials. Due to the excellent early strength and setting efficiency, as well as outstanding strength stability and durability, these geopolymer cementitious materials have broad application prospects in the fields of construction, roads, water conservancy, and other engineering projects.
[0039] The following examples further illustrate the mixed powder composition for preparing geopolymer cementitious materials according to the present invention, its preparation method, and its application. The examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.
[0040] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.
[0041] In the following examples and comparative examples, the coal gasification slag was provided by Ningxia Coal Basic Construction Co., Ltd., and its composition was 52.53% SiO2, 26.65% Al2O3, 9.76% CaO, 5.69% Fe2O3, 3.02% MgO, and 2.35% other impurities. The fly ash was provided by Datang Tongzhou Technology Co., Ltd., and its composition is 47.32% SiO2, 45.29% Al2O3, 1.95% Fe2O3, 1.86% CaO, 1.51% TiO2, 0.56% MgO and 1.51% other impurities.
[0042] Example 1 (1) Mix and grind 1000g of coal gasification slag, 20g of desulfurization gypsum and 30g of sodium sulfate, and then sieve to obtain modified coal gasification slag (specific surface area of 400m²). 2 / kg, particle size 300 mesh); (2) Mix 300g of modified coal gasification slag with 700g of fly ash evenly; (3) Mix 160g of water glass (modulus 1.4) with 40g of ground red mud (particle size 300 mesh) evenly to obtain a composite activator; (4) Mix 920g of the mixture obtained in step (2) with 80g of composite activator to obtain a mixed powder composition; (5) Mix 400g of water and 1000g of mixed powder composition, stir for 5min until a uniform slurry is formed, then pour the slurry into a mold, vibrate to form, and cure at 25℃ for 28 days to obtain geopolymer cementitious material S1.
[0043] Example 2 (1) Mix and grind 1000g of coal gasification slag, 15g of desulfurized gypsum and 20g of sodium sulfate, and then sieve to obtain modified coal gasification slag (specific surface area of 420m²). 2 / kg, particle size is 380 mesh); (2) Mix 200g of modified coal gasification slag with 800g of fly ash evenly; (3) Mix 60g of water glass (modulus 1.2) with 20g of ground red mud (particle size 280 mesh) evenly to obtain a composite activator; (4) Mix 950g of the mixture obtained in step (2) with 50g of composite activator to obtain a mixed powder composition; (5) Mix 350g of water and 1000g of mixed powder composition, stir for 5 minutes to form a uniform slurry, then pour the slurry into a mold, vibrate to form, and cure at 25°C for 28 days to obtain geopolymer cementitious material S2.
[0044] Example 3 (1) Mix and grind 1000g of coal gasification slag, 30g of desulfurization gypsum and 50g of sodium sulfate, and then sieve to obtain modified coal gasification slag (specific surface area of 450m²). 2 / kg, particle size is 350 mesh); (2) Mix 400g of modified coal gasification slag with 800g of fly ash evenly; (3) Mix 140g of water glass (modulus 1.5) with 20g of ground red mud (particle size 250 mesh) evenly to obtain a composite activator; (4) Mix 900g of the mixture obtained in step (2) with 100g of the composite activator to obtain a mixed powder composition; (5) Mix 450g of water and 1000g of mixed powder composition, stir for 5 minutes to form a uniform slurry, then pour the slurry into a mold, vibrate to form, and cure at 25°C for 28 days to obtain geopolymer cementitious material S3.
[0045] Example 4 The method described in Example 1 is implemented, except that in step (1), the amount of desulfurized gypsum used is 60g, and the geopolymer cementitious material S4 is finally obtained.
[0046] Example 5 The method described in Example 1 was implemented, except that in step (1), the amount of Glauber's salt used was 110g, and the geopolymer cementitious material S5 was finally obtained.
[0047] Example 6 The method described in Example 1 is implemented, except that in step (2), 100g of modified coal gasification slag and 1000g of fly ash are mixed evenly to finally obtain geopolymer cementitious material S6.
[0048] Example 7 The method described in Example 1 is implemented, except that in step (2), 800g of modified coal gasification slag and 1000g of fly ash are mixed evenly to finally obtain geopolymer cementitious material S7.
[0049] Example 8 The method described in Example 1 is implemented, except that in step (4), 800g of the mixture obtained in step (2) is mixed evenly with 200g of composite activator to finally obtain geopolymer cementitious material S8.
[0050] Comparative Example 1 The method described in Example 1 is implemented, except that step (1) is omitted. In step (2), the modified coal gasification slag is replaced with an equal mass of coal gasification slag, and the geopolymer cementitious material D1 is finally obtained.
[0051] Comparative Example 2 The method described in Example 1 is implemented, except that step (2) is omitted. In step (4), the modified coal gasification slag and fly ash mixture of the same mass are replaced with the modified coal gasification slag and fly ash mixture, and finally the geopolymer cementitious material D2 is obtained.
[0052] Comparative Example 3 The method described in Example 1 is implemented, except that step (2) is omitted. In step (4), an equal mass of fly ash is used to replace the modified coal gasification slag and fly ash mixture, and finally, geopolymer cementitious material D3 is obtained.
[0053] Comparative Example 4 The method described in Example 1 is implemented, except that in step (2), 90g of modified coal gasification slag and 1000g of fly ash are mixed evenly to finally obtain geopolymer cementitious material D4.
[0054] Comparative Example 5 The method described in Example 1 is implemented, except that in step (2), 900g of modified coal gasification slag and 1000g of fly ash are mixed evenly to finally obtain geopolymer cementitious material D5.
[0055] Test case (1) The compressive strength of the geopolymer cementitious materials prepared in the examples and comparative examples was tested on the 7th day and the 28th day using the method of GB / T 17671-2021 "Test Method for Strength of Cement Mortar". The results are shown in Table 1.
[0056] (2) The water absorption rate of the geopolymer cementitious materials prepared in the examples and comparative examples was tested using the method of Appendix A of GB / T 17671-2021 "Method for Determination of Water Absorption Rate of Cement Mortar". The results are shown in Table 1.
[0057] Table 1
[0058] As shown in Table 1, the geopolymer cementitious materials (S1-S8) prepared in the embodiments of the present invention exhibit significantly higher compressive strengths at 7 days and 28 days than the comparative examples (D1-D5), and significantly lower water absorption rates. This indicates that the geopolymer cementitious materials prepared by the method of the present invention possess superior early strength, later strength, and durability. Among them, Example 3 demonstrates the best performance, achieving a compressive strength of 34.2 MPa at 7 days and 50.1 MPa at 28 days, with a water absorption rate of only 6.5%.
[0059] Comparing Example 1 with Comparative Example 1, it can be seen that modifying coal gasification slag (mixing desulfurized gypsum and sodium sulfate powder) can significantly improve the strength of geopolymer cementitious materials and reduce water absorption. Unmodified coal gasification slag, due to its high porosity and low activity, results in poor product performance. Comparing Example 1 with Comparative Examples 2 and 3, it can be seen that the combined use of modified coal gasification slag and fly ash can achieve a complementary and synergistic effect. When modified coal gasification slag or fly ash is used alone as a raw material, the strength and durability of the product both decrease significantly. Comparing Example 1 with Examples 6 and 7 and Comparative Examples 4 and 5, it can be seen that when the mass ratio of modified coal gasification slag to fly ash is in the range of 0.2-0.6:1, the product performance is better. Outside this range, the strength decreases and the water absorption increases. In addition, Examples 4 and 5 show that when the amount of desulfurized gypsum and sodium sulfate exceeds the preferred range, the product performance decreases slightly, indicating that the raw material ratio needs to be controlled within a reasonable range to ensure the best effect.
[0060] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing a mixed powder composition for preparing geopolymer cementitious materials, characterized in that, The method includes the following steps: (1) Mix and grind coal gasification slag, desulfurization gypsum and mirabilite to obtain modified coal gasification slag; (2) Mix the modified coal gasification slag with fly ash; (3) Solid water glass is mixed with red mud to obtain a composite activator; (4) Mix the composite activator with the mixture obtained in step (2); The mass ratio of the modified coal gasification slag to the fly ash is 0.1-0.8:
1.
2. The method according to claim 1, characterized in that, In step (2), the mass ratio of the modified coal gasification slag to the fly ash is 0.2-0.6:1; Preferably, the modified coal gasification slag has a specific surface area ≥ 400 m². 2 / kg, particle size ≤300 mesh.
3. The method according to claim 1 or 2, characterized in that, In step (1), the mass ratio of the coal gasification slag to the desulfurization gypsum is 100:1-5, preferably 100:1.2-4.
4. The method according to claim 1 or 2, characterized in that, The mass ratio of the coal gasification slag to the sodium sulfate is 100:1-10, preferably 100:2-8.
5. The method according to any one of claims 1-4, characterized in that, In step (3), the mass ratio of the solid water glass to the red mud is 1-10:
1.
6. The method according to any one of claims 1-5, characterized in that, In step (3), the modulus of the solid water glass is 1-2; and / or The red mud has a particle size of ≤300 mesh.
7. The method according to any one of claims 1-6, characterized in that, In step (4), the mass ratio of the composite activator to the mixture obtained in step (2) is 1:5-30.
8. A mixed powder composition prepared by the method according to any one of claims 1-7.
9. A geopolymer cementitious material, characterized in that, The geopolymer cementitious material is prepared by mixing the mixed powder composition of claim 8 with water.
10. The application of the geopolymer cementitious material according to claim 9 in the construction of buildings, roads, water conservancy projects and the production of building materials.