A high-strength hard gypsum material and its production process

Abstract

The invention discloses a high-strength hard gypsum material and a production process thereof, belonging to the technical field of building materials. The method comprises the following steps: S1, adding modified fiber to silicate cement slurry, mixing uniformly, and obtaining reinforced cement slurry; S2, grinding anhydrite into powder, adding water and a modified water-reducing agent, adding a retarder, and stirring uniformly to obtain a mixture; S3, adding the reinforced cement slurry to the mixture, stirring and mixing, and calcining at 150-180°C for 4-6 hours to obtain the high-strength hard gypsum material. The invention uses anhydrite as a matrix and reduces the water consumption of the prepared gypsum material and the voids generated in the hardening process of the gypsum material by introducing the modified water-reducing agent. Meanwhile, the introduced reinforced cement slurry can generate a large amount of C-S-H gel in the hydration process to fill the voids in the anhydrite and cover the surface of the anhydrite particles. The synergistic effect of the two further improves the strength of the prepared gypsum material.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a high-strength hard gypsum material and a production process thereof. Background Art

[0002] Gypsum, a hydrate primarily composed of calcium sulfate, offers excellent thermal insulation, fire resistance, noise reduction, and humidity control. It is widely used as an inorganic non-metallic material in various fields, including architecture, sculpture, model making, and the medical field. Gypsum products made with it as the primary raw material have long been favored by various industries for their excellent processing properties, ease of molding, and affordability. Beta-hemihydrate gypsum, in particular, forms a robust lattice structure during hardening, exhibiting high mechanical strength and durability, making it a key choice in the construction and decorative materials sectors.

[0003] At present, in order to ensure the dispersibility and fluidity of the gypsum material slurry during use, it is necessary to add a water amount far higher than the theoretical requirement for hemihydrate gypsum to be converted into dihydrate gypsum. During the hardening process of the gypsum material slurry, excess water will escape from the hardened gypsum material in the form of water vapor, causing a large number of voids to be generated in the structure of the hardened gypsum material. The gypsum material thus becomes loose and porous, and its strength and hardness are greatly reduced. In addition, the dihydrated calcium sulfate produced during the hydration process of the gypsum material has a large solubility, which makes the gypsum material easily dissolve in water, damaging the structure of the gypsum crystals, resulting in a significant decrease in the strength of the gypsum material. Therefore, how to improve the toughness of the gypsum material is a technical problem that needs to be solved at present. Summary of the Invention

[0004] The object of the present invention is to provide a high-strength hard gypsum material and a production process thereof to solve the problems in the background technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A production process for high-strength gypsum material comprises the following steps:

[0007] S1. Adding modified fiber to silicate cement slurry and mixing evenly to obtain reinforced cement slurry;

[0008] S2. Grind the anhydrite into powder, add water and modified water-reducing agent, add retarder, and stir evenly to obtain a mixture;

[0009] S3. Add reinforced cement slurry to the mixture, stir and mix, and then calcine at 150-180° C. for 4-6 hours to obtain high-strength hard gypsum material.

[0010] Furthermore, the weight ratio of the silicate cement slurry and the modified fiber is 70:0.5-1; the weight ratio of the anhydrite, water, modified water reducer and retarder is 100-120:30-40:0.5-1:0.3; and the usage ratio of the mixture and the reinforced cement slurry is 90-110:10.

[0011] Furthermore, the modified fiber is prepared by the following steps:

[0012] A1. Add nano-silica to toluene, ultrasonically disperse at room temperature for 2 hours, add silane coupling agent hydrolyzate, reflux at 40-55°C for 5-6 hours, cool, filter, wash, and dry to obtain modified nano-silica; and obtain nano-silica grafted with silane coupling agent by an elimination reaction between the silane coupling agent and the hydroxyl groups on the surface of the nano-silica.

[0013] A2. Add modified nano-silica to toluene, stir and mix, add triethylenediamine, mix evenly, add polyvinyl alcohol fiber, and react at 100-110°C for 2-3 hours. After cooling, filter, wash with deionized water, and dry to obtain modified fiber; use triethylenediamine as a catalyst to react the epoxy group on the surface of the modified nano-silica with the hydroxyl group on the surface of the polyvinyl alcohol fiber to obtain polyvinyl alcohol fiber grafted with nano-silica.

[0014] Furthermore, the usage ratio of the toluene, nano-silica, and silane coupling agent hydrolyzate is 40 mL: 1.5-4 g: 2 mL; the silane coupling agent hydrolyzate is prepared by dissolving 0.5-2 g of silane coupling agent KH-560 in 5 mL of water.

[0015] Furthermore, the usage ratio of the toluene, modified nano-silica, triethylenediamine and polyvinyl alcohol fiber is 60 mL: 1.5-2 g: 0.4 g: 8-14 g.

[0016] Furthermore, the aspect ratio of the polyvinyl alcohol fiber is 800-900.

[0017] Furthermore, the modified water-reducing agent is prepared by the following steps:

[0018] B1. Maleic anhydride was added to glycidol, stirred and mixed, and then p-toluenesulfonic acid was added. The mixture was stirred and reacted at 70-75° C. for 0.5-1 h. The temperature was then lowered to 60° C., polyphosphoric acid was added, and the mixture was stirred and reacted for 1-2 h. After cooling, a modified glycerophosphate was obtained. Using p-toluenesulfonic acid as a catalyst, a ring-opening reaction occurred between the hydroxyl group of glycidol and the anhydride of maleic anhydride to obtain a glycerol monoester, which was then polymerized with polyphosphoric acid to obtain a modified glycerophosphate containing maleic acid.

[0019] B2, in distilled water, add isobutylene alcohol polyoxyethylene ether, stirring and dissolving under 25-35 ℃ of condition, then add modified glycerophosphate and acrylic acid, after mixing, drip thioglycolic acid and ascorbic acid, stirring and dissolving, then under 50-60 ℃ of condition, drip the hydrogen peroxide that concentration is 30wt% while stirring, stop stirring after dropwising, and continue reaction 5-6h, after cooling, be 20wt% sodium hydroxide solution regulating pH value to 6-7 with concentration, obtain modified water-reducing agent; With ascorbic acid and hydrogen peroxide as initiator, thioglycolic acid is chain-transfer agent, macromonomer isobutylene alcohol polyoxyethylene ether and acrylic acid are reacted and synthesize polycarboxylic acid intermediate, and then with modified glycerophosphate polymerization, obtain the modified water-reducing agent that main chain contains modified glycerophosphate.

[0020] Furthermore, the usage ratio of the glycidol, maleic anhydride, p-toluenesulfonic acid and polyphosphoric acid is 20 mL: 10-15 g: 1-5 g: 15-20 mL.

[0021] Furthermore, the usage ratio of the distilled water, isobutylene alcohol polyoxyethylene ether, modified glycerol phosphate, acrylic acid, thioglycolic acid, ascorbic acid and hydrogen peroxide is 100 mL: 20-30 mL: 0.5 mL: 50-55 mL: 0.5 mL: 0.2 g: 4-8 mL.

[0022] A high-strength hard gypsum material is produced by the above production process.

[0023] Beneficial effects of the present invention:

[0024] The modified fiber of the present invention is grafted with nano-silica on its surface, forming microscopic nano-scale protrusions on the surface of the modified fiber, thereby increasing the roughness of the surface of the modified fiber. When blended with silicate cement slurry, the modified fiber and silicate cement slurry are mechanically interlocked, the interfacial bonding strength between the modified fiber and silicate cement slurry is improved, and the modified fiber is evenly dispersed in the silicate cement slurry, thereby strengthening the silicate cement slurry.

[0025] The modified water-reducing agent of the present invention introduces modified glycerophosphate into the main chain. When mixed with anhydrite under hydration conditions, a large number of carboxyl groups are generated. The modified water-reducing agent molecules are adsorbed on the anhydrite surface through complexation with calcium ions on the anhydrite surface, so that the modified water-reducing agent is uniformly dispersed in the anhydrite matrix. The electrostatic repulsion and steric hindrance effect enhance the dispersion between anhydrite particles, thereby enabling the anhydrite to obtain good dispersibility when using a small amount of water, thereby reducing the water consumption of the prepared gypsum material. At the same time, the glycerol generated by the hydrolysis of the ester group in the modified glycerophosphate can compete with water molecules for hydration sites in the early stage of anhydrite hydration, reducing the hydration of water molecules with the anhydrite, thereby enhancing the retarding effect of the anhydrite during hydration.

[0026] The present invention uses anhydrite as a matrix and, through the introduction of a modified water-reducing agent, improves the dispersibility between anhydrite particles, reduces the water consumption of the prepared gypsum material, and thus reduces the voids generated in the gypsum material during the hardening process, making the internal structure of the hardened gypsum material more compact, thereby enhancing the strength and hardness of the gypsum material. Simultaneously, the introduced reinforced cement slurry can generate a large amount of CSH gel during the hydration process, which fills the voids in the anhydrite, forming a gypsum material with a more compact and firm internal structure. Furthermore, the reinforced cement slurry can also form a CSH gel coating on the surface of the anhydrite particles, thereby reducing the dissolution of the anhydrite during the hydration process. Therefore, through the synergistic effect of the modified water-reducing agent and the reinforced cement slurry, the strength and hardness of the prepared gypsum material can be further improved. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment provides a modified fiber, which is prepared by the following steps:

[0030] A1. Add 1.5 g of nano-silica to 40 mL of toluene, ultrasonically disperse at room temperature for 2 h, add 2 mL of a silane coupling agent hydrolyzate prepared by dissolving 0.5 g of silane coupling agent KH-560 in 5 mL of water, reflux at 40°C for 5 h, cool, filter, wash, and dry to obtain modified nano-silica;

[0031] A2. Add 1.5 g of modified nano-silica to 60 mL of toluene, stir and mix, add 0.4 g of triethylenediamine, mix evenly, add 8 g of polyvinyl alcohol fiber, and react at 100 ° C for 2 h. After cooling, filter, wash with deionized water, and dry to obtain modified fiber.

[0032] Example 2

[0033] This embodiment provides a modified fiber, which is prepared by the following steps:

[0034] A1. Add 3 g of nano-silica to 40 mL of toluene, ultrasonically disperse at room temperature for 2 h, add 2 mL of a silane coupling agent hydrolyzate prepared by dissolving 1 g of silane coupling agent KH-560 in 5 mL of water, reflux at 45°C for 5.5 h, cool, filter, wash, and dry to obtain modified nano-silica;

[0035] A2. Add 1.8 g of modified nano-silica to 60 mL of toluene, stir and mix, add 0.4 g of triethylenediamine, mix evenly, add 10 g of polyvinyl alcohol fiber, and react at 105 ° C for 2.5 hours. After cooling, filter, wash with deionized water, and dry to obtain modified fiber.

[0036] Example 3

[0037] This embodiment provides a modified fiber, which is prepared by the following steps:

[0038] A1. Add 4 g of nano-silica to 40 mL of toluene, ultrasonically disperse for 2 h at room temperature, add 2 mL of a silane coupling agent hydrolyzate prepared by dissolving 2 g of silane coupling agent KH-560 in 5 mL of water, reflux at 55°C for 6 h, cool, filter, wash, and dry to obtain modified nano-silica;

[0039] A2. Add 2 g of modified nano-silica to 60 mL of toluene, stir and mix, add 0.4 g of triethylenediamine, mix evenly, add 14 g of polyvinyl alcohol fiber, and react at 110 ° C for 3 h. After cooling, filter, wash with deionized water, and dry to obtain modified fiber.

[0040] Example 4

[0041] This embodiment provides a modified water-reducing agent, which is prepared by the following steps:

[0042] B1. Add 10 g of maleic anhydride to 20 mL of glycidol, stir and mix, then add 1 g of p-toluenesulfonic acid, stir and react at 70° C. for 0.5 h, then cool to 60° C., add 15 mL of polyphosphoric acid, continue stirring and react for 1 h, and cool to obtain modified glycerophosphate;

[0043] B2, 20mL of isobutylene alcohol polyoxyethylene ether was added to 100mL of distilled water, and the mixture was stirred and dissolved at 25°C. Then, 0.5mL of modified glycerophosphate and 50mL of acrylic acid were added. After mixing, 0.5mL of thioglycolic acid and 0.2g of ascorbic acid were added dropwise, and the mixture was stirred and dissolved. Then, 4mL of 30wt% hydrogen peroxide was added dropwise while stirring at 50°C. Stirring was stopped after completion of the addition, and the reaction was continued for 5h. After cooling, the pH value was adjusted to 6 with sodium hydroxide solution to obtain a modified water-reducing agent.

[0044] Example 5

[0045] This embodiment provides a modified water-reducing agent, which is prepared by the following steps:

[0046] B1. Add 13 g of maleic anhydride to 20 mL of glycidol, stir and mix, then add 3 g of p-toluenesulfonic acid, stir and react at 73 ° C for 0.5 h, then cool to 60 ° C, add 18 mL of polyphosphoric acid, continue stirring and react for 1.5 h, and cool to obtain modified glycerophosphate;

[0047] B2, 25mL isobutylene alcohol polyoxyethylene ether was added to 100mL distilled water, stirring and dissolving under 30°C conditions, then 0.5mL modified glycerophosphate and 53mL acrylic acid were added, after mixing, 0.5mL thioglycolic acid and 0.2g ascorbic acid were added dropwise, stirring and dissolving, then 6mL of hydrogen peroxide with a concentration of 30wt% was added dropwise while stirring under 55°C conditions, stirring was stopped after completion of the addition, and the reaction was continued for 5.5h, and after cooling, the pH value was adjusted to 6.5 with sodium hydroxide solution to obtain modified water-reducing agent.

[0048] Example 6

[0049] This embodiment provides a modified water-reducing agent, which is prepared by the following steps:

[0050] B1. Add 15 g of maleic anhydride to 20 mL of glycidol, stir and mix, then add 5 g of p-toluenesulfonic acid, stir and react at 75 ° C for 1 h, then cool to 60 ° C, add 20 mL of polyphosphoric acid, continue stirring and react for 2 h, and cool to obtain modified glycerophosphate;

[0051] B2, 30mL of isobutylene alcohol polyoxyethylene ether was added to 100mL of distilled water, and the mixture was stirred and dissolved at 35°C. Then, 0.5mL of modified glycerophosphate and 55mL of acrylic acid were added. After mixing, 0.5mL of thioglycolic acid and 0.2g of ascorbic acid were added dropwise, and the mixture was stirred and dissolved. Then, 8mL of hydrogen peroxide with a concentration of 30wt% was added dropwise while stirring at 60°C. Stirring was stopped after completion of the addition, and the reaction was continued for 6h. After cooling, the pH value was adjusted to 7 with sodium hydroxide solution to obtain a modified water-reducing agent.

[0052] Example 7

[0053] This embodiment provides a production process for high-strength hard gypsum material, comprising the following steps:

[0054] S1. Add 0.5 parts by weight of modified fiber to 70 parts by weight of silicate cement slurry, mix well, and obtain reinforced cement slurry;

[0055] S2. Grind 100 parts by weight of anhydrite into powder, add 30 parts by weight of water and 0.5 parts by weight of modified water-reducing agent, and add 0.3 parts by weight of retarder, stir well, and obtain a mixture;

[0056] S3. Add 10 parts by weight of reinforced cement slurry to 90 parts by weight of the mixture, stir and mix, and then calcine at 150° C. for 4 hours to obtain a high-strength hard gypsum material.

[0057] Example 8

[0058] This embodiment provides a production process for high-strength hard gypsum material, comprising the following steps:

[0059] S1. Add 0.8 parts by weight of modified fiber to 70 parts by weight of silicate cement slurry, mix well, and obtain reinforced cement slurry;

[0060] S2, 110 parts by weight of anhydrite were ground into powder, 35 parts by weight of water and 0.8 parts by weight of modified water-reducing agent were added, and 0.3 parts by weight of retarder were added at the same time, and stirred to obtain a mixture;

[0061] S3. Add 10 parts by weight of reinforced cement slurry to 100 parts by weight of the mixture, stir and mix, and then calcine at 160° C. for 5 hours to obtain a high-strength hard gypsum material.

[0062] Example 9

[0063] This embodiment provides a production process for high-strength hard gypsum material, comprising the following steps:

[0064] S1. Add 1 part by weight of modified fiber to 70 parts by weight of silicate cement slurry, mix well, and obtain reinforced cement slurry;

[0065] S2, 120 parts by weight of anhydrite were ground into powder, 40 parts by weight of water and 1 part by weight of modified water-reducing agent were added, and 0.3 parts by weight of retarder were added at the same time, and stirred to obtain a mixture;

[0066] S3. Add 10 parts by weight of reinforced cement slurry to 110 parts by weight of the mixture, stir and mix, and then calcine at 180° C. for 6 hours to obtain a high-strength hard gypsum material.

[0067] Comparative Example 1: Compared with Example 7, no modified fiber was added, and the rest were the same.

[0068] Comparative Example 2: Compared with Example 7, the modified water-reducing agent was replaced with a commercially available polycarboxylate water-reducing agent in equal amounts, and the rest were the same.

[0069] Comparative Example 3: Compared with Example 7, no reinforcing cement is added, and the rest is the same.

[0070] Performance tests were conducted on Examples 7 to 9 and Comparative Examples 1 to 3. The flexural strength and compressive strength were measured in accordance with GB / T 9776-2008. The water consumption for standard consistency, setting time, and flowability were measured in accordance with GB / T 17669.4-1999. The results are shown in Table 1.

[0071] Table 1

[0072]

[0073] As can be seen from Table 1, the standard consistency water consumption of the gypsum materials prepared by the enhanced cement slurry and the modified water-reducing agent in Examples 7-9 is significantly lower than that of the standard consistency water consumption of Comparative Examples 1-3, and the neat slurry fluidity is higher than that of Comparative Examples 1-3, indicating that the modified water-reducing agent improves the dispersibility between the gypsum material particles. In addition, the setting time of Examples 7-9 is also higher than that of Comparative Examples 2-3, indicating that the modified water-reducing agent has a certain retarding effect; compared with Comparative Examples 2 and 3, Example 7 has higher flexural strength and compressive strength, indicating that under the synergistic effect of the enhanced cement slurry and the modified water-reducing agent, the prepared gypsum material has higher toughness.

[0074] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0075] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A production process for high-strength gypsum material, characterized in that: The following steps are involved: S1. Adding modified fiber to silicate cement slurry and mixing evenly to obtain reinforced cement slurry; S2. Grind the anhydrite into powder, add water and modified water-reducing agent, add retarder, and stir evenly to obtain a mixture; S3, adding reinforced cement slurry to the mixture, stirring and mixing, and calcining at 150-180° C. for 4-6 hours to obtain a high-strength hard gypsum material; The modified fiber is prepared by the following steps: A1. Add nano-silica to toluene, ultrasonically disperse at room temperature for 2 hours, add silane coupling agent hydrolyzate, reflux at 40-55°C for 5-6 hours, cool, filter, wash, and dry to obtain modified nano-silica; A2. Add modified nano-silica to toluene, stir and mix, add triethylenediamine, mix well, add polyvinyl alcohol fiber, and react at 100-110°C for 2-3 hours. After cooling, filter, wash with deionized water, and dry to obtain modified fiber; The modified water-reducing agent is prepared by the following steps: B1. Add maleic anhydride to glycidol, stir and mix, then add p-toluenesulfonic acid, stir and react at 70-75°C for 0.5-1h, then cool to 60°C, add polyphosphoric acid, continue stirring and react for 1-2h, and cool to obtain modified glycerophosphate; B2. Add isobutylene alcohol polyoxyethylene ether into distilled water, stir and dissolve at 25-35 ° C, then add modified glycerol phosphate and acrylic acid, mix well, add thioglycolic acid and ascorbic acid dropwise, stir and dissolve, then add hydrogen peroxide with a concentration of 30wt% while stirring at 50-60 ° C, stop stirring after completion of the addition, and continue the reaction for 5-6h, after cooling, adjust the pH value to 6-7 with sodium hydroxide solution to obtain a modified water reducer.

2. The production process of a high-strength hard gypsum material according to claim 1, characterized in that: The weight ratio of the silicate cement slurry to the modified fiber is 70:0.5-1; the weight ratio of the anhydrite, water, modified water reducer and retarder is 100-120:30-40:0.5-1:0.3; and the usage ratio of the mixed material and the reinforced cement slurry is 90-110:

10.

3. The production process of a high-strength gypsum material according to claim 1, characterized in that: The dosage ratio of the toluene, nano-silica and silane coupling agent hydrolyzate is 40 mL: 1.5-4 g: 2 mL; the silane coupling agent hydrolyzate is prepared by dissolving 0.5-2 g of silane coupling agent KH-560 in 5 mL of water.

4. The production process of a high-strength gypsum material according to claim 1, characterized in that: The usage ratio of the toluene, modified nano-silica, triethylenediamine and polyvinyl alcohol fiber is 60 mL: 1.5-2 g: 0.4 g: 8-14 g.

5. The production process of a high-strength hard gypsum material according to claim 1, characterized in that: The aspect ratio of the polyvinyl alcohol fiber is 800-900.

6. The production process of a high-strength hard gypsum material according to claim 1, characterized in that: The usage ratio of the glycidol, maleic anhydride, p-toluenesulfonic acid and polyphosphoric acid is 20 mL: 10-15 g: 1-5 g: 15-20 mL.

7. The production process of a high-strength gypsum material according to claim 1, characterized in that: The usage ratio of the distilled water, isobutylene alcohol polyoxyethylene ether, modified glycerophosphate, acrylic acid, thioglycolic acid, ascorbic acid and hydrogen peroxide is 100 mL: 20-30 mL: 0.5 mL: 50-55 mL: 0.5 mL: 0.2 g: 4-8 mL.

8. A high-strength gypsum material, characterized in that: Prepared according to the production process according to any one of claims 1 to 7.

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