Preparation method of graphene oxide loaded nano silicon dioxide composite material and cement reinforcing method

Abstract

The invention discloses a preparation method of a graphene oxide loaded nano silicon dioxide composite material and a cement reinforcing method, and the preparation method comprises the following steps: S1, mixing graphite powder with concentrated sulfuric acid, adding potassium permanganate, reacting, and adding a hydrogen peroxide solution to stop the reaction to obtain a first reaction solution; filtering the first reaction liquid, washing the first reaction liquid with water until the first reaction liquid is neutral (pH is 6.5-7.5), dispersing the first reaction liquid in deionized water, and performing ultrasonic treatment to obtain graphene oxide dispersion liquid; s2, adding a silane coupling agent into the graphene oxide dispersion liquid, adjusting the pH value to 8-9, and carrying out a reaction to obtain a second reaction liquid; s3, adding a silicate ester silicon source into the second reaction solution, adding an acid solution to adjust the pH value to 2-4, and reacting to obtain a third reaction solution; s4, carrying out centrifugal separation, washing and drying on the third reaction liquid to obtain a graphene oxide loaded nano silicon dioxide composite material; when the composite material prepared by the method is used for cement, the mixing amount is small and the reinforcing effect is excellent.

Description

Technical Field

[0001] This application relates to the field of composite material preparation technology, and in particular to a method for preparing graphene oxide-supported nano-silica composite materials and a cement reinforcement method. Background Technology

[0002] In the production and preparation of cement-based materials, admixtures are usually added to improve the strength and overall performance of cement. However, traditional cement admixtures (such as silica fume and fly ash) have limited activity and can only partially increase the amount of cement hydration products, thus only partially improving the density of cement stone. Although chemical admixtures can usually reduce the water-cement ratio, they cannot deeply optimize the pore structure of cement stone.

[0003] Existing research utilizes nanomaterials to enhance the performance of cement-based materials. Studies have shown that adding nano-graphene and nano-silica yields superior results in improving the strength and durability of cement-based materials. Graphene oxide is a nanomaterial with a thickness on the nanometer scale and a two-dimensional plane on the micrometer scale. Its surface often contains oxygen-containing functional groups, which, in addition to its high strength, can form chemical bonds with cement hydration products, optimizing product distribution. Furthermore, its two-dimensional plane can exert a template effect, promoting the growth of hydration products along the template plane and improving the bonding ability between hydration products and graphene. In summary, the addition of graphene oxide to cement-based materials can effectively inhibit microcrack propagation and improve the mechanical properties of the material. Nano-silica, being one-dimensional nanoparticles, possesses a high specific surface area, resulting in high activity that accelerates the secondary hydration reaction with cement, generating more CSH gel. Simultaneously, its nanoscale advantage can fill the pores of cement stone, significantly refining the pore size.

[0004] However, both have limitations when used alone: ​​the template effect of graphene oxide is limited, and the hydration products are oriented in a low degree in the template direction, resulting in a weak bonding ability between graphene oxide and the cement paste bulk phase, and failing to fully utilize the mechanical property advantages of graphene oxide itself. When high amounts of nano-SiO2 are incorporated, agglomeration is prone to occur, resulting in a low effective dispersion concentration, and it can easily lead to a sharp increase in the viscosity of cement paste, causing a significant deterioration in workability. Summary of the Invention

[0005] To address the drawbacks of incorporating graphene oxide and nano-silica into cement alone, a composite material prepared by graphene oxide-supported nano-silica and a cement reinforcement method are provided.

[0006] The objective of this invention is achieved through the following technical solutions: A method for preparing graphene oxide-supported nano-silica composite material includes the following steps: S1: Mix graphite powder with concentrated sulfuric acid, add potassium permanganate to react; after the reaction is complete, add hydrogen peroxide solution to stop the reaction and obtain the first reaction solution; filter the first reaction solution, wash with water until neutral (pH 6.5-7.5), disperse in deionized water, and sonicate to obtain graphene oxide dispersion; S2: Add the silane coupling agent to the graphene oxide dispersion obtained in step S1, adjust the pH value to 8-9 to carry out the reaction, and obtain the second reaction solution; S3: Add a silicate ester silicon source to the second reaction solution, add acid to adjust the pH value to 2-4, and react to obtain the third reaction solution; S4: The third reaction solution was centrifuged, washed, and dried to obtain a graphene oxide-supported nano-silica composite material.

[0007] By employing the above technical solution, the pre-reaction of graphene oxide with silane coupling agent, under alkaline conditions, hydrolyzes the coupling agent to generate silanol groups, which then undergo ring-opening or condensation reactions with the epoxy / carboxyl groups on the surface of graphene oxide, forming a covalently bonded interface. In an acidic environment, the addition of silicate-based silicon sources allows for in-situ nucleation and growth of nano-SiO2 on the surface of graphene oxide sheets via a sol-gel method, achieving uniform distribution of nano-silica on the graphene surface and reducing agglomeration. The use of silane coupling agent further enhances the interfacial bonding between the two, forming stable chemical bonds. Acidic conditions inhibit the rapid self-aggregation of SiO2 particles, forcing silicate ions to preferentially adsorb onto the coupling agent-modified graphene oxide surface, forming a "GO-SiO2 core-shell structure." This composite structure maintains the high specific surface area and excellent mechanical properties of graphene while fully utilizing the pozzolanic activity of nano-silica, requiring only a low dosage to optimize the density and mechanical properties of the cement matrix.

[0008] Optionally, the silane coupling agent is 3-aminopropyltriethoxysilane or 3-glycidoxypropyltrimethoxysilane.

[0009] By adopting the above technical solution, the amino group of 3-aminopropyltriethoxysilane and the carboxyl group of graphene oxide form a covalent bond through an amidation reaction, which enhances the interfacial binding energy and prevents SiO2 from falling off; while the epoxy group of 3-glycidoxypropyltrimethoxysilane reacts with the hydroxyl group of graphene oxide through ring opening to form an ether bond; the silanol groups after hydrolysis of both can condense with the SiO2 precursor, the amino group of 3-aminopropyltriethoxysilane can catalyze the SiO2 condensation rate, and the long chain of 3-glycidoxypropyltrimethoxysilane enhances the steric hindrance effect; both silane coupling agents have a better effect on enhancing the interfacial binding between graphene oxide and SiO2.

[0010] Optionally, the amount of silane coupling agent added is 5% to 15% of the mass of graphene oxide.

[0011] By adopting the above technical solution, we can avoid the uneven SiO2 loading caused by insufficient modification sites on the graphene oxide surface when the amount added is too small; at the same time, we can avoid the excess coupling agent from self-aggregating into low molecular weight siloxane fragments when the amount added is too large, occupying the active sites of graphene oxide and hindering the effective loading. Within this range, we can achieve monodisperse loading of nano-SiO2 on the graphene oxide surface and avoid stress concentration caused by particle agglomeration.

[0012] Optionally, the silicate source is tetraethyl orthosilicate.

[0013] By adopting the above technical solution, tetraethyl orthosilicate is used as a silicate silicon source. Its hydrolysis and condensation rate is controllable. Under acidic conditions with a pH of 2 to 4, the ethoxy group of tetraethyl orthosilicate is gradually hydrolyzed into silicic acid, and then a Si-O-Si network is formed on the surface of graphene oxide through a condensation reaction. At the same time, the low viscosity of tetraethyl orthosilicate allows it to quickly penetrate into the spaces between graphene oxide to form a through-type SiO2 supported structure.

[0014] Optionally, the amount of tetraethyl orthosilicate added is 80% to 200% of the mass of graphene oxide.

[0015] By adopting the above technical solution, when the amount of tetraethyl orthosilicate is too small, the SiO2 layer thickness is <5nm, which cannot completely cover the surface of graphene oxide; when the amount of tetraethyl orthosilicate is too large, the excess tetraethyl orthosilicate self-aggregates into free SiO2 particles; within this range, both the two-dimensional reinforcement effect of graphene oxide and the pozzolanic activity of nano-SiO2 are utilized.

[0016] Optionally, in step S3, after adding the silicate-based silicon source, tributyl phosphate is also added.

[0017] By adopting the above technical solution, the phosphate ester can be selectively adsorbed on the surface of silicic acid or silanol groups to form a steric hindrance layer, which hinders the collision and aggregation of SiO2 particles, slows down the silicic acid condensation reaction rate, makes the average particle size of SiO2 smaller, and improves the dispersibility of SiO2.

[0018] The second objective of this invention is achieved through the following technical solution: A cement reinforcement method includes the following steps: mixing the graphene oxide-supported nano-silica composite material prepared by any of the above-mentioned graphene oxide-supported nano-silica composite material preparation methods with water, dispersing it to obtain a suspension, and adding it to cement slurry under stirring. The dosage of the graphene oxide-supported nano-silica composite material is 0.02% to 0.08% of the cement mass.

[0019] By adopting the above technical solutions, the composite material is uniformly dispersed, and the composite material provides heterogeneous nucleation sites in the cement paste to promote CSH gel formation; the pozzolanic reaction of silica produces additional cementitious materials; the bridging effect of graphene improves toughness and crack resistance; the composite material within this range can significantly improve the mechanical properties and durability of cement-based materials.

[0020] Optionally, the dosage of graphene oxide-supported nano-silica composite material is 0.03% to 0.05% of the cement mass.

[0021] By adopting the above technical solution, the reinforcement effect is not obvious if the composite material dosage is too low. At the same time, it can also avoid the possibility that the graphene sheet stacking may cause local stress concentration and microcracks when the composite material dosage is too high. The composite material has a better effect on cement reinforcement within this dosage range.

[0022] In summary, this application has at least the following beneficial effects: (1) Under alkaline conditions, graphene oxide and silane coupling agent pre-react to form a covalent bond interface, which promotes the uniform distribution of nano-silica on the graphene surface and effectively improves the agglomeration problem of nanoparticles. (2) In an acidic environment, silicate ester silicon sources hydrolyze and condense in situ on the modified graphene oxide sheets to grow nano-silica particles, forming a tightly bonded "silicon-carbon binary structure" and enhancing the interfacial stability of the composite material. (3) The silicon-carbon binary structure can synergistically leverage the advantages of graphene oxide’s high mechanical load-bearing capacity and nano-silica’s high pozzolanic activity and nano-size effect, thus endowing cement-based materials with excellent comprehensive performance at low dosage. Detailed Implementation

[0023] raw material Graphite powder, grade TS-1, with fixed carbon of 99.9wt%, ash content of 0.1wt% to 10wt%, moisture content of 0.2wt%, and particle size (μm) of ≥60%. The detection equipment, a laser particle size distribution meter, was purchased from Qingdao Tianyuan Graphite Co., Ltd. Tetraethyl orthosilicate, with a tetraethyl orthosilicate content of 99.7 wt%, an ethanol content of 0.4 wt%, and a polyethyl orthosilicate content of 0.1 wt%, was purchased from Ningxia Shenglan Chemical Environmental Protection Technology Co., Ltd. Methyl orthosilicate, with a content of 99.6 wt% methyl orthosilicate, 0.35 wt% methanol, and 0.05 wt% polymethyl silicate, was purchased from Ningxia Shenglan Chemical Environmental Protection Technology Co., Ltd. 3-Aminopropyltriethoxysilane, purity ≥99wt%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. 3-Glycidyl etheroxypropyltrimethoxysilane, purity ≥97.0 wt%, purchased from THIAI (Shanghai) Chemical Industry Development Co., Ltd. Dodecyltrimethoxysilane, purity ≥95wt%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Octyltriethoxysilane, purity ≥97wt%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Tributyl phosphate, purity ≥99wt%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. The P·O 42.5 grade ordinary silicate cement, potassium permanganate, sodium silicate, 98wt% concentrated sulfuric acid, 10wt% hydrochloric acid, 30wt% hydrogen peroxide solution, 30wt% ammonia water, and anhydrous ethanol are all commercially available.

[0024] Example 1 A graphene oxide-supported nano-silica composite material is prepared by the following method: S1: Mix 10g of graphite powder with 110mL of 98wt% concentrated sulfuric acid in a reaction vessel, add 30g of potassium permanganate, place the reaction vessel in a 0℃ ice-water bath for 2 hours, then place the reaction vessel in a 40℃ oil bath for 2 hours. After the reaction is complete, add 500mL of deionized water to dilute and obtain a diluted solution. Add 60mL of 15wt% hydrogen peroxide solution dropwise to the diluted solution at a rate of 1.5mL / min to terminate the reaction and obtain the first reaction solution. Centrifuge the first reaction solution at 8000rpm to obtain the separated product. Wash the separated product with deionized water until neutral, i.e., pH 7.0±0.1, and centrifuge at 8000rpm to obtain graphene oxide. Weigh 15g of graphene oxide, disperse it in 2000mL of deionized water, and sonicate at 300W for 40min to obtain a graphene oxide dispersion. S2: Add 1.5g of 3-aminopropyltriethoxysilane to the graphene oxide dispersion obtained in step S1, add 30wt% ammonia to adjust the pH to 8.5±0.1, and stir at 30rpm for 3h at 60℃ to obtain the second reaction solution. S3: Add 15g of tetraethyl orthosilicate to the second reaction solution obtained in step S2, add 10wt% dilute hydrochloric acid to adjust the pH to 3±0.1, react at 50℃ for 9h, adjust the temperature to 40℃ and react for 3h to obtain the third reaction solution; S4: The third reaction solution was centrifuged at 8000 rpm for 10 min, washed 4 times alternately with anhydrous ethanol and deionized water, and vacuum dried at 70℃ for 18 h to obtain graphene-supported nano-silica composite material.

[0025] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0026] Comparative Example 1 A graphene oxide-supported nano-silica composite material differs from Example 1 in that: no silane coupling agent is added in step S2, while the rest is the same as in Example 1.

[0027] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0028] Comparative Example 2 A graphene oxide-supported nano-silica composite material differs from Example 1 in that sodium silicate is used in place of tetraethyl orthosilicate by mass, while the rest is the same as in Example 1.

[0029] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement. The graphene oxide-supported nano-silica composite material was thus obtained by comparison.

[0030] Example 2 A graphene oxide-supported nano-silica composite material differs from Example 1 in that: dodecyltrimethoxysilane is used in place of 3-aminopropyltriethoxysilane by mass, while the rest is the same as in Example 1.

[0031] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement. The graphene oxide-supported nano-silica composite material was obtained from this example.

[0032] Example 3 A graphene oxide-supported nano-silica composite material differs from Example 1 in that octyltriethoxysilane is used in place of 3-aminopropyltriethoxysilane by mass, while the rest is the same as in Example 1.

[0033] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0034] Example 4 A graphene oxide-supported nano-silica composite material differs from Example 1 in that 3-glycidyl etheroxypropyltrimethoxysilane is used in place of 3-aminopropyltriethoxysilane by mass, while the rest is the same as in Example 1.

[0035] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0036] Example 5 A graphene oxide-supported nano-silica composite material, which differs from Example 1 in that: 0.75g of 3-aminopropyltriethoxysilane is used, while the rest of the components are the same as in Example 1.

[0037] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0038] Example 6 A graphene oxide-supported nano-silica composite material differs from Example 1 in that: 2.25g of 3-aminopropyltriethoxysilane is used, while the rest of the components are the same as in Example 1.

[0039] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0040] Example 7 A graphene oxide-supported nano-silica composite material differs from Example 1 in that: 0.3g of 3-aminopropyltriethoxysilane is used, while the rest of the material is the same as in Example 1.

[0041] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0042] Example 8 A graphene oxide-supported nano-silica composite material, which differs from Example 1 in that: 3-aminopropyltriethoxysilane is 3g, and the rest is the same as in Example 1.

[0043] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0044] Example 9 A graphene oxide-supported nano-silica composite material differs from Example 1 in that it uses methyl orthosilicate in place of ethyl orthosilicate, while the rest is the same as in Example 1.

[0045] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0046] Example 10 A graphene oxide-supported nano-silica composite material differs from Example 1 in that 12g of tetraethyl orthosilicate is added, while the rest is the same as in Example 1.

[0047] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0048] Example 11 A graphene oxide-supported nano-silica composite material differs from Example 1 in that 30g of tetraethyl orthosilicate is added, while the rest is the same as in Example 1.

[0049] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0050] Example 12 A graphene oxide-supported nano-silica composite material differs from Example 1 in that 7.5g of tetraethyl orthosilicate is added, while the rest is the same as in Example 1.

[0051] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0052] Example 13 A graphene oxide-supported nano-silica composite material differs from Example 1 in that 37.5g of tetraethyl orthosilicate is added, while the rest is the same as in Example 1.

[0053] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0054] Example 14 A graphene oxide-supported nano-silica composite material differs from Example 1 in that: in step S3, 0.5g of tributyl phosphate is added after adding tetraethyl orthosilicate and before adding hydrochloric acid to adjust the pH; the rest is the same as in Example 1.

[0055] A type of reinforced cement mortar is obtained by the following reinforcement method: 180g of graphene-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0056] Comparative Example 3 A graphene oxide-supported nano-silica composite material, identical to that in Example 14.

[0057] A type of reinforced cement mortar is obtained by the following reinforcement method: 45g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0058] Comparative Example 4 A graphene oxide-supported nano-silica composite material, identical to that in Example 14.

[0059] A type of reinforced cement mortar is obtained by the following reinforcement method: 450g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0060] Example 15 A graphene oxide-supported nano-silica composite material, identical to that in Example 14.

[0061] A type of reinforced cement mortar is obtained by the following reinforcement method: 135g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0062] Example 16 A graphene oxide-supported nano-silica composite material, identical to that in Example 14.

[0063] A type of reinforced cement mortar is obtained by the following reinforcement method: 225g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0064] Example 17 A graphene oxide-supported nano-silica composite material, identical to that in Example 14.

[0065] A type of reinforced cement mortar is obtained by the following reinforcement method: 90g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3 The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0066] Example 18 A graphene oxide-supported nano-silica composite material, identical to that in Example 14.

[0067] A type of reinforced cement mortar is obtained by the following reinforcement method: 360g of graphene oxide-supported nano-silica composite material is mixed with 10L of deionized water and ultrasonically dispersed at 300W for 5min to obtain a suspension. The suspension is then added to a 1m³ container at a rate of 1L / min. 3The cement slurry was stirred at 200 rpm and then at 500 rpm for 15 minutes to obtain reinforced cement mortar. The cement slurry contained 450 kg of cement, 1350 kg of standard sand, and 215 kg of water. The cement was P·O 42.5 grade ordinary Portland cement.

[0068] Examples 1-18 and Comparative Examples 1-4 were tested. The 3-day and 28-day compressive strength and flexural strength of the cement mortar were tested according to GB / T 17671-2021 "Test Method for Strength of Cement Mortar". The test results are shown in Table 1.

[0069] Table 1 Comparative test results of each embodiment Based on Table 1, the analyses of Examples 1-18 and Comparative Examples 1-4 are as follows: Compared with Example 1, the 3-day and 28-day compressive strength and flexural strength of cement mortar in Example 1 are greater than those of cement mortar in Comparative Example 1.

[0070] The difference between Example 1 and Comparative Example 1 is that Example 1 uses a silane coupling agent to treat graphene oxide; the use of the silane coupling agent enhances the interfacial bonding between graphene oxide and nano-silica, forming a stable chemical bond. Therefore, it is necessary to treat graphene oxide with a silane coupling agent.

[0071] Compared with Example 1, the 3-day and 28-day compressive strength and flexural strength of cement mortar in Example 1 are greater than those of cement mortar in Example 2.

[0072] The difference between Example 1 and Comparative Example 2 is that Example 1 uses silicate ester as silicon source; silicate ester silicon sources are more easily hydrolyzed into silicic acid in an acidic environment, which can be used to generate nano-SiO2; it can be seen that using silicate ester as silicon source is necessary.

[0073] Comparing Examples 1 and Examples 2-4, the 3-day and 28-day compressive strength and flexural strength of cement mortar in Example 1 are greater than those of cement mortar in Examples 2-3; the 3-day and 28-day compressive strength and flexural strength of cement mortar in Example 1 are close to those of cement mortar in Example 4.

[0074] The difference between Examples 1 and Examples 2-4 is as follows: In Example 1, the silane coupling agent is 3-aminopropyltriethoxysilane, while in Example 4, the silane coupling agent is 3-glycidoxypropyltrimethoxysilane. The amino group of 3-aminopropyltriethoxysilane forms a covalent bond with the carboxyl group of graphene oxide through an amidation reaction, enhancing the interfacial binding energy and preventing SiO2 from detaching. The epoxy group of 3-glycidoxypropyltrimethoxysilane undergoes ring-opening and reacts with the hydroxyl group of graphene oxide to form an ether bond. 3-aminopropyltriethoxysilane and 3-glycidoxypropyltrimethoxysilane are more effective than other silane coupling agents. Therefore, 3-aminopropyltriethoxysilane or 3-glycidoxypropyltrimethoxysilane is the preferred silane coupling agent.

[0075] Comparing Examples 1, 5-6, and 7-8, the 3-day and 28-day compressive strength and flexural strength of the cement mortar in Example 1 are greater than those in Examples 5-8; the 3-day and 28-day compressive strength and flexural strength of the cement mortar in Examples 5-6 are also greater than those in Examples 7-8.

[0076] The difference between Examples 1 and Examples 5-8 is that in Examples 1 and 5-6, the silane coupling agent is 5%-15% of the mass of graphene oxide, while in Example 1, the silane coupling agent is 10% of the mass of graphene oxide. Within this range, the amount of silane coupling agent added avoids uneven loading of nano-SiO2 on the surface of graphene oxide and prevents stress concentration caused by particle agglomeration. Therefore, a silane coupling agent content of 5%-15% of the mass of graphene oxide is preferred, and a silane coupling agent content of 10% of the mass of graphene oxide is also preferred within this range.

[0077] Comparing Example 1 and Example 9, the 3-day and 28-day compressive strength and flexural strength of the cement mortar in Example 1 are greater than those of the cement mortar in Example 9.

[0078] The difference between Example 1 and Example 9 is that in Example 1, the silicate silicon source is tetraethyl orthosilicate. Compared with other silicate silicon sources, tetraethyl orthosilicate has a slower and more controllable hydrolysis rate, which is more conducive to the formation of more uniform silica. Therefore, tetraethyl orthosilicate is the preferred silicate silicon source.

[0079] Comparing Examples 1 and 10-13, the 3-day and 28-day compressive strength and flexural strength of the cement mortar in Example 1 are greater than those of the cement mortar in Examples 10-13; the 3-day and 28-day compressive strength and flexural strength of the cement mortar in Examples 10-11 are greater than those of the cement mortar in Examples 12-13.

[0080] The difference between Examples 1, 10-11, and 12-13 is that in Examples 1 and 10-11, the amount of tetraethyl orthosilicate added is 80%-200% of the mass of graphene oxide, while in Example 1, the amount of tetraethyl orthosilicate added is 100% of the mass of graphene oxide. Within this range, the SiO2 thickness formed by tetraethyl orthosilicate is moderate and provides complete coverage, without forming free SiO2 particles. Therefore, an addition amount of 80%-200% of the mass of graphene oxide is preferred, and an addition amount of 100% of the mass of graphene oxide is also preferred within this range.

[0081] Comparing Example 1 and Example 14, the 3-day and 28-day compressive strength and flexural strength of the cement mortar in Example 14 are both greater than those of the cement mortar in Example 1.

[0082] The difference between Example 1 and Example 14 is that in Example 14, tributyl phosphate was added after tetraethyl orthosilicate. Tributyl phosphate hinders the collision and aggregation of SiO2 particles, slows down the rate of silicic acid condensation reaction, and improves the dispersibility of SiO2. It can be seen that adding tributyl phosphate after tetraethyl orthosilicate is better.

[0083] Comparing Examples 14, 3-4, and 15-18, the 3-day and 28-day compressive and flexural strengths of the cement mortar in Example 14 are greater than those in Comparative Examples 3-4 and 15-18; the 3-day and 28-day compressive and flexural strengths of the cement mortar in Examples 15-18 are greater than those in Comparative Examples 3-4; and the 3-day and 28-day compressive and flexural strengths of the cement mortar in Examples 15-16 are greater than those in Examples 17-18.

[0084] The differences between Examples 14, 15-16, 17-18, and Comparative Examples 3-4 are as follows: the composite material in Examples 14-18 is 0.02%-0.08% of the cement mass, the composite material in Examples 14-16 is 0.03%-0.05% of the cement mass, and the composite material in Example 14 is 0.04% of the cement mass. A composite material content of 0.02%-0.08% of the cement mass is sufficient to improve the performance of cement-based materials, and a composite material content of 0.03%-0.05% of the cement mass has a superior effect on cement reinforcement. Therefore, a composite material content of 0.02%-0.08% of the cement mass is necessary, 0.03%-0.05% is preferred, and 0.03% of the cement mass is preferred within this range.

[0085] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of protection claimed by the present invention, they are protected by patent law.

Claims

1. A method for preparing a graphene oxide supported nanosilica composite material, characterized in that, The method comprises the following steps: S1: mixing graphite powder with concentrated sulfuric acid, adding potassium permanganate for reaction; after the reaction is completed, adding hydrogen peroxide solution to stop the reaction, to obtain a first reaction liquid; filtering the first reaction liquid, washing with water until neutral (pH 6.5-7.5), dispersing in deionized water, and ultrasonic treatment to obtain a graphene oxide dispersion liquid; S2: adding a silane coupling agent to the graphene oxide dispersion liquid obtained in step S1, adjusting the pH value to 8-9 for reaction, to obtain a second reaction liquid; S3: adding a silicate silicon source to the second reaction liquid, adding acid to adjust the pH value to 2-4, and reacting to obtain a third reaction liquid; S4: obtaining a graphene oxide loaded nanosilica composite material after centrifugal separation, washing, and drying of the third reaction liquid.

2. The method for preparing a graphene oxide-supported nano-silica composite material according to claim 1, characterized in that, The silane coupling agent is 3-aminopropyl triethoxysilane or 3-glycidyl ether oxypropyl trimethoxysilane.

3. The method for preparing a graphene oxide-supported nano-silica composite material according to claim 2, characterized in that, The addition amount of the silane coupling agent is 5%-15% of the mass of the graphene oxide.

4. The method for preparing a graphene oxide-supported nano-silica composite material according to claim 1, characterized in that, The silicate silicon source is tetraethyl orthosilicate.

5. The method for preparing a graphene oxide-supported nano-silica composite material according to claim 4, characterized in that, The addition amount of the tetraethyl orthosilicate is 80%-200% of the mass of the graphene oxide.

6. The method for preparing a graphene oxide-supported nano-silica composite material according to claim 1, characterized in that, After adding the silicate silicon source in step S3, tributyl phosphate is also added.

7. A method of cement enhancement, characterized by, The method comprises the following steps: mixing the graphene oxide loaded nanosilica composite material prepared by the method according to any one of claims 1-6 with water, obtaining a suspension after dispersion, and adding the suspension into cement paste under stirring, wherein the graphene oxide loaded nanosilica composite material accounts for 0.02%-0.08% of the mass of the cement.

8. A method of cement augmentation according to claim 7, wherein, The graphene oxide loaded nanosilica composite material accounts for 0.03%-0.05% of the mass of the cement.

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