Cement-based binder and method for its production

Abstract

The application relates to the technical field of building materials, in particular to a cement-based cementitious material and a preparation method thereof, which is composed of the following components in parts by weight: 60-100 parts of Portland cement, 20-30 parts of active mineral admixture, 3-7 parts of composite nanomaterial, 100-120 parts of fine aggregate, 0.8-1.3 parts of water reducing agent, 1-2 parts of additive and 12-16 parts of water. The cement-based cementitious material in the application is prepared by introducing the composite nanomaterial into the cementitious material matrix composed of the Portland cement, the active mineral admixture, the fine aggregate, the water reducing agent, the additive and water, so that the cement-based cementitious material has excellent breaking strength and structural stability, can bear heavy vehicle rolling, equipment standing and frequent personnel passing, and can guarantee the firmness and durability of the floor and prolong the service life from the root.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a cement-based cementitious material and its preparation method. Background Technology

[0002] The C40 high-strength cement self-leveling terrazzo system is made with C40 grade cement-based materials as the core, combined with various types of high-wear-resistant aggregates such as corundum, natural colored stones, and quartz sand, and integrated with a refined terrazzo process. This system combines the high compressive strength and high hardness advantages of C40 materials with its self-leveling properties. Through a rich mix of aggregates, it achieves a diverse balance between decoration and performance, delivering a refined terrazzo texture that fulfills the triple value of "high strength and durability + convenient construction + diverse aesthetics," precisely meeting the stringent requirements of high-end residential underground garages, modern high-tech factories, and other similar settings.

[0003] As the core structural material of the system, it meets the C40 concrete strength grade standard, with a compressive strength ≥40MPa. It possesses excellent flexural strength and structural stability, capable of withstanding heavy vehicle pressure, static equipment placement, and frequent pedestrian traffic, ensuring the floor's durability from the outset. Simultaneously, it is compatible with self-leveling processes, exhibiting good fluidity and setting stability, laying a solid foundation for subsequent paving and terrazzo processes, precisely matching the stringent strength requirements of high-end scenarios. Therefore, to meet the demanding needs of high-end residential underground garages, modern high-tech factories, and other similar scenarios, there is an urgent need to design a cementitious material with high compressive strength and good flexural resistance. Summary of the Invention

[0004] In view of the problems mentioned in the background art above, the purpose of this invention is to provide a cement-based cementitious material and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A cement-based cementitious material is composed of the following components by weight: 60-100 parts silicate cement, 20-30 parts active mineral admixtures, 3-7 parts composite nanomaterials, 100-120 parts fine aggregates, 0.8-1.3 parts water-reducing agent, 1-2 parts additives, and 12-16 parts water. The water-reducing agent is a polycarboxylate-based water-reducing agent. The fine aggregate is selected from continuously graded quartz sand with a particle size of 0.15-0.6 mm and a mud content of ≤1%.

[0006] As a further preferred embodiment of the present invention, the active mineral admixture is composed of slag powder, silica fume, and ultrafine fly ash in a mass ratio of (5-6):(3-4):(2-3); The additive is composed of nano-calcium carbonate, hydroxyethyl methyl cellulose, and zinc phosphate in a mass ratio of (4-5):(2-3):1.

[0007] As a further preferred embodiment of the present invention, the preparation method of the composite nanomaterial is as follows: 1) Calcium nitrate and silica sol were mixed and used as a precursor, and then added to an ethanol aqueous solution along with a regulator. After being ultrasonically dispersed evenly, a mixed solution was obtained. 2) Add porous nanosheets to the mixed solution, disperse them evenly by ultrasonication, transfer them to a hydrothermal reactor, react at a constant temperature for 14-16 hours, and after the reaction is completed, allow them to cool naturally to room temperature. After centrifugation, freeze-dry to obtain the composite nanomaterial.

[0008] Furthermore, in step 1), the ratio of calcium nitrate, silica sol, regulator, and ethanol aqueous solution is (10-15) g: (8-12) g: (42-48) g: (550-600) mL; The regulator is composed of polyethylene glycol and polyvinylpyrrolidone in a mass ratio of 1:(1.2-1.5); The mass concentration of the ethanol aqueous solution is 17-20 wt%.

[0009] Furthermore, in step 2), the solid-liquid ratio of the porous nanosheets and the mixed solution is 1g:(15-25)mL; The temperature of the isothermal reaction is 170-180℃.

[0010] As a further preferred embodiment of the present invention, the method for preparing the porous nanosheets is as follows: 1) Montmorillonite and intercalating agent are added to the solvent in sequence and stirred and dispersed at room temperature to obtain a precursor suspension; 2) Transfer the precursor suspension to a hydrothermal reactor and react at a constant temperature for 10-13 hours. After naturally cooling to room temperature, centrifuge at 4500-5500 r / min for 20-30 minutes to remove multiple layers of precipitate. Take the upper layer and centrifuge at 11000-12000 r / min for 35-40 minutes to collect the middle layer suspension, thus obtaining the purified nanosheet suspension. 3) Add the template agent to the nanosheet suspension, sonicate at 55-58℃ for 5-8 hours with 80-100W, then wash with deionized water and ethanol alternately and freeze-dry to obtain porous nanosheets with a single-layer large pore structure.

[0011] Furthermore, in step 1), the ratio of the amount of montmorillonite, intercalating agent, and solvent is (10-15) g: (130-150) g: (500-800) mL; The intercalating agent is composed of hexadecyltrimethylammonium bromide and triethanolamine in a mass ratio of 1:(3-4); The solvent is composed of deionized water and ethanol in a volume ratio of (4-5):1.

[0012] Furthermore, in step 2), the temperature of the isothermal reaction is 110-115℃.

[0013] Furthermore, in step 3), the ratio of the template agent to the nanosheet suspension is (2.5-3.0) g: (200-260) mL; The template agent is composed of sodium carbonate, citric acid and polyethylene glycol in a mass ratio of 1:(2.3-2.8):(0.5-0.8).

[0014] A method for preparing a cement-based cementitious material, comprising the following specific steps: According to the weight proportions, mix silicate cement, active mineral admixtures, fine aggregates and additives, then add composite nanomaterials, stir evenly, then add water-reducing agent and water, and stir thoroughly until evenly mixed.

[0015] The beneficial effects of this invention are: In this invention, an intercalating agent can be efficiently inserted into the interlayer gaps of layered montmorillonite, significantly weakening the interlayer van der Waals forces, which is beneficial for the subsequent peeling of intact monolayers without damaging the crystal structure of montmorillonite. Furthermore, triethanol, as a small-molecule alkanolamine compound, can pre-introduce active groups such as hydroxyl and amino groups on the nanosheet surface, enhancing the interfacial bonding with the cementitious gel matrix and facilitating the subsequent deposition of nanorods onto the nanosheet surface to form a strong bond. Then, through a hydrothermal reaction, the precursor interlayers are continuously and uniformly bonded under the synergistic effect of the intercalating agent and solvent molecules. By uniformly spreading the layers and completely weakening the interlayer forces, a complete thin-layer exfoliation is achieved. After gradient centrifugation purification and separation, porous nanosheets with a monolayer large-pore structure are obtained. Then, an inorganic calcium-silicon precursor and a regulator are added to an ethanol-water solution and stirred to obtain a mixed solution. The porous nanosheets are used as the matrix material and added to the mixed solution. After hydrothermal reaction, nanorods are generated. Due to the abundance of hydroxyl active sites on the surface of the nanorods, the nanorods and porous nanosheets can not only form a strong interface bond through hydrogen bonding, but the nanorods can also be embedded in the porous nanosheets. By inserting nanorods into the pores of porous nanosheets, a vertically intercalated structure of nanorods is formed on the porous nanosheets, thus obtaining a composite nanomaterial. When this composite nanomaterial is introduced into a cement-based gel material, the intercalation between the nanorods allows the composite nanomaterial to form a multi-layered continuous phase structure through interlocking connections. This creates layer upon layer of "rigid partitions" within the gel material, making the structure more compact and dispersing localized pressure over a larger area, preventing stress concentration and making it more resistant to crushing and external forces, thus exhibiting excellent resistance. In addition to compressive strength, the "rigid diaphragm" formed by the framework has a layered structure with high strength. When a crack encounters the "rigid diaphragm" during its propagation, it is forced to deflect, making the propagation path longer and consuming a large amount of energy, thus inhibiting crack propagation. Moreover, the composite nanomaterial has many active groups on its surface, resulting in high interfacial bonding strength with the cement-based gel material. This means that when the crack pulls the composite nanomaterial from the gel material, it needs to overcome interfacial friction, resulting in huge energy consumption, which further inhibits crack propagation. As a result, the gel material has strong flexural resistance and high flexural strength.

[0016] The cement-based gel material of this invention introduces composite nanomaterials into a gel material matrix composed of silicate cement, active mineral admixtures, fine aggregates, water-reducing agents, additives, and water. The active mineral admixtures can fill pores, optimize the structure of hydration products, and improve the density of the matrix. The fine aggregates can enhance the overall skeletal stability of the material and reduce shrinkage deformation. The modifier can strengthen the interfacial bonding, optimize the crystal structure of hydration products, and improve structural stability. The composite nanomaterials can disperse stress and inhibit crack propagation, enhancing the compressive strength and flexural strength of the gel material. Thus, the cement-based gel material has excellent flexural strength and structural stability, and can withstand heavy vehicle rolling, equipment idling, and frequent personnel passage, ensuring the floor is solid, durable, and has a long service life from the source. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In this embodiment of the invention, a polycarboxylate-based water-reducing agent is selected; The fine aggregate is continuously graded quartz sand with a particle size of 0.15-0.6mm and a mud content of ≤1%. The active mineral admixture is composed of slag powder, silica fume, and ultrafine fly ash in a mass ratio of 5:3:2, with the slag powder particle size ≤45μm, the silica fume specific surface area ≥15000㎡ / kg, and the ultrafine fly ash being Class I fly ash. The additive consists of nano-calcium carbonate, hydroxyethyl methyl cellulose, and zinc phosphate in a mass ratio of 4:2:1. Example 1

[0019] A cement-based cementitious material is composed of the following components in parts by weight: 60 parts silicate cement, 20 parts active mineral admixtures, 3 parts composite nanomaterials, 100 parts fine aggregate, 0.8 parts water-reducing agent, 1 part additive, and 12 parts water. The specific preparation method is as follows: According to the weight proportions, mix silicate cement, active mineral admixtures, fine aggregates and additives, then add composite nanomaterials, stir evenly, then add water-reducing agent and water, and stir thoroughly until evenly mixed.

[0020] The preparation methods of composite nanomaterials are as follows: 1) Add 10g of montmorillonite and 130g of intercalating agent composed of hexadecyltrimethylammonium bromide and triethanolamine in a mass ratio of 1:3 to 500mL of solvent composed of deionized water and ethanol in a volume ratio of 4:1. After stirring and dispersing at room temperature, a precursor suspension is obtained. 2) The precursor suspension was transferred to a hydrothermal reactor and reacted at 110°C for 10 hours. After naturally cooling to room temperature, it was centrifuged at 4500 r / min for 20 minutes to remove the multilayer precipitate. The upper layer was taken and centrifuged at 11000 r / min for 35 minutes to collect the middle layer suspension, thus obtaining the purified nanosheet suspension. 3) Add 2.5g of template agent composed of sodium carbonate, citric acid and polyethylene glycol in a mass ratio of 1:2.3:0.5 to 200mL of nanosheet suspension. Sonicate at 80W for 5h at 55℃. Then wash with deionized water and ethanol alternately and freeze-dry to obtain porous nanosheets with a single-layer large pore structure. 4) Mix 10g of calcium nitrate and 8g of silica sol as a precursor, and add it sequentially with 42g of a regulator composed of polyethylene glycol and polyvinylpyrrolidone in a mass ratio of 1:1.2 into 550mL of 17wt% ethanol aqueous solution. After ultrasonic dispersion, a mixed solution is obtained. 5) Add porous nanosheets to the mixed solution at a solid-liquid ratio of 1g:15mL. After ultrasonic dispersion, transfer the mixture to a hydrothermal reactor and react at 170℃ for 14h. After the reaction is complete, allow it to cool to room temperature naturally. After centrifugation, freeze-dry to obtain the composite nanomaterial. Example 2

[0021] A cement-based cementitious material is composed of the following components in parts by weight: 80 parts silicate cement, 25 parts active mineral admixtures, 5 parts composite nanomaterials, 110 parts fine aggregate, 1 part water-reducing agent, 1.5 parts additives, and 15 parts water. The specific preparation method is as follows: According to the weight proportions, mix silicate cement, active mineral admixtures, fine aggregates and additives, then add composite nanomaterials, stir evenly, then add water-reducing agent and water, and stir thoroughly until evenly mixed.

[0022] The preparation methods of composite nanomaterials are as follows: 1) Add 12g of montmorillonite and 140g of intercalating agent composed of hexadecyltrimethylammonium bromide and triethanolamine in a mass ratio of 1:3.5 to 700mL of solvent composed of deionized water and ethanol in a volume ratio of 4.5:1. After stirring and dispersing at room temperature, a precursor suspension is obtained. 2) The precursor suspension was transferred to a hydrothermal reactor and reacted at 112°C for 12 hours. After naturally cooling to room temperature, it was centrifuged at 5000 r / min for 25 min to remove the multilayer precipitate. The upper layer was taken and centrifuged at 12000 r / min for 36 min to collect the middle layer suspension, thus obtaining the purified nanosheet suspension. 3) Add 2.8g of template agent composed of sodium carbonate, citric acid and polyethylene glycol in a mass ratio of 1:2.5:0.6 to 240mL of nanosheet suspension. Sonicate at 100W for 7h at 56℃. After repeated washing with deionized water and ethanol, freeze-dry to obtain porous nanosheets with a single-layer large pore structure. 4) Mix 13g of calcium nitrate and 10g of silica sol as a precursor, and add it sequentially with 45g of a regulator composed of polyethylene glycol and polyvinylpyrrolidone in a mass ratio of 1:1.3 into 580mL of 18wt% ethanol aqueous solution. After ultrasonic dispersion, a mixed solution is obtained. 5) Add porous nanosheets to the mixed solution at a solid-liquid ratio of 1g:20mL. After ultrasonic dispersion, transfer the mixture to a hydrothermal reactor and react at 175℃ for 15h. After the reaction is complete, allow it to cool to room temperature naturally. After centrifugation, freeze-dry the mixture to obtain the composite nanomaterial. Example 3

[0023] A cement-based cementitious material is composed of the following components in parts by weight: 100 parts silicate cement, 30 parts active mineral admixtures, 7 parts composite nanomaterials, 120 parts fine aggregate, 1.3 parts water-reducing agent, 2 parts additives, and 16 parts water. The specific preparation method is as follows: According to the weight proportions, mix silicate cement, active mineral admixtures, fine aggregates and additives, then add composite nanomaterials, stir evenly, then add water-reducing agent and water, and stir thoroughly until evenly mixed.

[0024] The preparation methods of composite nanomaterials are as follows: 1) Add 15g of montmorillonite and 150g of intercalating agent composed of hexadecyltrimethylammonium bromide and triethanolamine in a mass ratio of 1:4 to 800mL of solvent composed of deionized water and ethanol in a volume ratio of 5:1. After stirring and dispersing at room temperature, a precursor suspension is obtained. 2) The precursor suspension was transferred to a hydrothermal reactor and reacted at 115°C for 13 hours. After naturally cooling to room temperature, it was centrifuged at 5500 r / min for 30 minutes to remove the multilayer precipitate. The upper layer was taken and centrifuged at 12000 r / min for 40 minutes to collect the middle layer suspension, thus obtaining the purified nanosheet suspension. 3) Add 3.0g of template agent composed of sodium carbonate, citric acid and polyethylene glycol in a mass ratio of 1:2.8:0.8 to 260mL of nanosheet suspension. Sonicate at 100W for 8h at 58℃. Then wash with deionized water and ethanol alternately and freeze-dry to obtain porous nanosheets with a single-layer large pore structure. 4) Mix 15g of calcium nitrate and 12g of silica sol as a precursor, and add it sequentially with 48g of a regulator composed of polyethylene glycol and polyvinylpyrrolidone in a mass ratio of 1:1.5 into 600mL of 20wt% ethanol aqueous solution. After ultrasonic dispersion, a mixed solution is obtained. 5) Add porous nanosheets to the mixed solution at a solid-liquid ratio of 1g:25mL. After ultrasonic dispersion, transfer the mixture to a hydrothermal reactor and react at 180℃ for 16h. After the reaction is complete, allow it to cool to room temperature naturally. After centrifugation, freeze-dry to obtain the composite nanomaterial.

[0025] Comparative Example 1: This comparative example is basically the same as Example 1, except that it does not contain composite nanomaterials.

[0026] Comparative Example 2: This comparative example is basically the same as Example 1, except that it does not contain active mineral admixtures.

[0027] Comparative Example 3: This comparative example is basically the same as Example 1, except that it does not contain any additives.

[0028] Comparative Example 4: This comparative example is basically the same as Example 1, except that in the preparation of the composite nanomaterial, the remaining steps 1)-3) are omitted.

[0029] Comparative Example 5: This comparative example is basically the same as Example 1, except that in the preparation of the composite nanomaterial, the remaining steps 4)-5) are omitted.

[0030] Test experiment: Using the methods provided in Examples 1-3 and Comparative Examples 1-5, gel material samples were obtained respectively. Then, they were mixed with sand, gravel, water and polycarboxylate superplasticizer at a mass ratio of 350:810:990:170:2 to obtain concrete. After curing for 28 days, the compressive strength and flexural strength were tested according to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)". The results are shown in Table 1.

[0031] Table 1

[0032] As shown in Table 1, the cement-based gel material of this invention has excellent flexural and compressive strength, good structural stability, and can withstand heavy vehicle rolling, equipment idling, and frequent personnel passage, thus ensuring the floor is solid, durable, and has a long service life.

[0033] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A cement-based binder, characterized in that, It is composed of the following components by weight: 60-100 parts silicate cement, 20-30 parts active mineral admixtures, 3-7 parts composite nanomaterials, 100-120 parts fine aggregates, 0.8-1.3 parts water-reducing agent, 1-2 parts additives, and 12-16 parts water; The water-reducing agent is a polycarboxylate-based water-reducing agent. The fine aggregate is selected from continuously graded quartz sand with a particle size of 0.15-0.6 mm and a mud content of ≤1%.

2. The cement-based binder according to claim 1, characterized in that, The active mineral admixture is composed of slag powder, silica fume, and ultrafine fly ash in a mass ratio of (5-6):(3-4):(2-3); The additive is composed of nano-calcium carbonate, hydroxyethyl methyl cellulose, and zinc phosphate in a mass ratio of (4-5):(2-3):

1.

3. The cement-based binder according to claim 1, characterized in that, The preparation method of the composite nanomaterial is as follows: 1) Calcium nitrate and silica sol were mixed and used as a precursor, and then added to an ethanol aqueous solution along with a regulator. After being ultrasonically dispersed evenly, a mixed solution was obtained. 2) Add porous nanosheets to the mixed solution, disperse them evenly by ultrasonication, transfer them to a hydrothermal reactor, react at a constant temperature for 14-16 hours, and after the reaction is completed, allow them to cool naturally to room temperature. After centrifugation, freeze-dry to obtain the composite nanomaterial.

4. The cement-based binder according to claim 3, characterized in that, In step 1), the ratio of calcium nitrate, silica sol, regulator, and ethanol aqueous solution is (10-15) g: (8-12) g: (42-48) g: (550-600) mL; The regulator is composed of polyethylene glycol and polyvinylpyrrolidone in a mass ratio of 1:(1.2-1.5); The mass concentration of the ethanol aqueous solution is 17-20 wt%.

5. A cement-based binder according to claim 3, characterized in that, In step 2), the solid-liquid ratio of the porous nanosheets and the mixed solution is 1g:(15-25)mL; The temperature of the isothermal reaction is 170-180℃.

6. The cement-based binder according to claim 3, characterized in that, The porous nanosheets are prepared as follows: 1) Montmorillonite and intercalating agent are added to the solvent in sequence and stirred and dispersed at room temperature to obtain a precursor suspension; 2) Transfer the precursor suspension to a hydrothermal reactor and react at a constant temperature for 10-13 hours. After naturally cooling to room temperature, centrifuge at 4500-5500 r / min for 20-30 minutes to remove multiple layers of precipitate. Take the upper layer and centrifuge at 11000-12000 r / min for 35-40 minutes to collect the middle layer suspension, thus obtaining the purified nanosheet suspension. 3) Add the template agent to the nanosheet suspension, sonicate at 55-58℃ for 5-8 hours with 80-100W, then wash with deionized water and ethanol alternately and freeze-dry to obtain porous nanosheets with a single-layer large pore structure.

7. A cement-based binder according to claim 6, characterized in that, In step 1), the ratio of montmorillonite, intercalating agent, and solvent is (10-15) g : (130-150) g ​​: (500-800) mL; The intercalating agent is composed of hexadecyltrimethylammonium bromide and triethanolamine in a mass ratio of 1:(3-4); The solvent is composed of deionized water and ethanol in a volume ratio of (4-5):

1.

8. A cement-based binder according to claim 6, characterized in that, In step 2), the temperature of the isothermal reaction is 110-115℃.

9. A cement-based binder according to claim 6, characterized in that, In step 3), the ratio of the template agent to the nanosheet suspension is (2.5-3.0) g : (200-260) mL; The template agent is composed of sodium carbonate, citric acid and polyethylene glycol in a mass ratio of 1:(2.3-2.8):(0.5-0.8).

10. A method for preparing a cement-based cementitious material according to any one of claims 1-9, characterized in that, The specific steps are as follows: According to the weight proportions, mix silicate cement, active mineral admixtures, fine aggregates and additives, then add composite nanomaterials, stir evenly, then add water-reducing agent and water, and stir thoroughly until evenly mixed.

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