Polyurethane nano-alumina composite repair material and preparation method thereof

Abstract

The invention discloses a polyurethane nanometer aluminum oxide composite repairing material and a preparation method thereof, and belongs to the technical field of tunnel engineering materials. The concrete comprises the following components in parts by mass: 350-400 parts of cement, 60-80 parts of fly ash, 40-60 parts of silica fume, 15-20 parts of polyurethane, 20-25 parts of nano aluminum oxide, 600-700 parts of sand, 4-6 parts of a water reducing agent and 170-190 parts of water. The cement-based composite repair material provided by the invention can simultaneously meet the requirements of setting time, permeability and coagulability. Due to the introduction of nano aluminum oxide, the compactness and the wear resistance of the material can be improved, and the permeability can be promoted, so that the material can permeate into a part with the smallest crack. The elastic characteristic of polyurethane is beneficial to keeping the repairing effect when the material deals with micro-deformation of the structure, and the bonding strength between a repairing area and an original structure is improved, so that the long-term stable repairing effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering materials, and specifically relates to a polyurethane nano-alumina composite repair material and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] In the construction of modern urban infrastructure, subway stations are important transportation hubs, and their structural safety and durability have received great attention. In particular, the side walls of subway stations are affected by factors such as the large volume of one-time concrete pouring and the dense distribution of steel bars, and often crack during operation, which leads to water leakage, seriously affecting the safety of the station and the comfort of passengers. At present, the main technology to solve this problem is a repair material based on cement-water glass double slurry. Although the cement-water glass double slurry repair material uses water glass as a quick-setting agent to shorten the setting time of the repair material and enable cracks to be repaired quickly, these materials are often difficult to penetrate into small cracks due to their poor permeability, and have poor adhesion to the original structure interface, which easily leads to the reappearance of cracks after repair, resulting in repeated damage and high maintenance costs. However, it is difficult to quickly realize the repair of subway stations without using quick-setting agents such as water glass, and long-term construction will bring inconvenience to passengers. It is difficult for the existing technology to meet the needs of setting time, permeability and coagulation at the same time. Summary of the invention

[0004] In order to address the deficiencies of the prior art, the purpose of the present invention is to provide a polyurethane nano-alumina composite repair material and a preparation method thereof. The repair material of the present invention enhances permeability through nanotechnology, allowing it to penetrate into tiny cracks, and utilizes polyurethane to improve interfacial adhesion to avoid recurrence of diseases. Innovative coagulation time regulation and optimized fluidity design make the material easy to construct and meet the needs of rapid repair. In addition, the addition of nano-alumina improves the microstructure and durability of the material, making the repair more durable and stable.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In the first aspect, the present invention provides a polyurethane nano-alumina composite repair material, comprising the following components in parts by weight: 350-400 parts of cement, 60-80 parts of fly ash, 40-60 parts of silica fume, 15-20 parts of polyurethane, 20-25 parts of nano-alumina, 600-700 parts of sand, 4-6 parts of water reducer, and 170-190 parts of water.

[0007] Preferably, the cement comprises 42.5 ordinary Portland cement.

[0008] Preferably, the fly ash is of grade I, with an average particle size of 10 to 30 μm and a specific surface area greater than 500 cm 2 / g.

[0009] Preferably, the mass percentage of silicon dioxide in the silica ash is not less than 97%, the volcanic ash activity index is greater than 95%, and the specific surface area is greater than 21.0 m 2 / g, density is 2.10~2.30g / cm 3 .

[0010] Preferably, the polyurethane is a cationic water-based polyurethane with a viscosity of 0.1 to 1 Pa·s and a solid content of 40% to 50%.

[0011] Preferably, the particle size of the nano-alumina is 5 to 10 nm.

[0012] Preferably, the sand is fine quartz sand with a mesh size of 200 and a bulk density of less than 1500 kg / m 3 .

[0013] Preferably, the water reducing agent is a polycarboxylic acid-based water reducing agent, with a solid content greater than 30%, a pH value of 7 to 8, and a water reduction rate of more than 30%.

[0014] In a second aspect, the present invention provides a polyurethane nano-alumina composite repair material as described in the first aspect, comprising the following steps:

[0015] S1. Mixing polyurethane with 20% to 30% of water to form a polyurethane solution;

[0016] S2, mixing cement, fly ash, silica fume, nano-alumina and sand to obtain a mixed dry component;

[0017] S3. Add the polyurethane solution and the remaining water to the mixed dry ingredients, stir evenly, then add a water reducing agent and stir to obtain a polyurethane nano-alumina composite repair material.

[0018] Preferably, in step S1, stirring is performed at 45 to 60 r / min for 3 to 5 min, in step S2, stirring is performed at 45 to 60 r / min for 3 to 5 min, in step S3, stirring is performed at 45 to 60 r / min for 2 to 3 min until stirring is uniform, and a water reducing agent is added and stirred at 140 to 160 r / min for 4 to 5 min.

[0019] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0020] The present invention introduces nano-alumina and polyurethane to achieve the penetration of repair materials into fine cracks in concrete, improve the bonding strength, provide a more lasting and stable repair effect, and help extend the service life of the concrete structure of the subway station.

[0021] The present invention achieves the characteristic of rapid setting by optimizing the material ratio rather than by adding an early setting agent, which enables the repair material to quickly harden and function without losing performance. It is very suitable for occasions that need urgent repair, such as the maintenance of public transportation facilities such as subway stations, and quickly restores the integrity and function of the facilities without interfering with normal operations. At the same time, by adjusting the ratio, the setting time of the material can be flexibly controlled according to the specific working conditions, so that it has better fluidity and permeability, can penetrate into tiny cracks, and achieve a more thorough repair effect, which is of great significance for the thorough treatment of structural cracks.

[0022] As an important filling material, nano-alumina can penetrate into extremely small cracks due to its nano-scale size. This high permeability ensures that the repair material can reach the deepest part of the crack and form a mechanical interlock with the inside of the crack, thereby achieving effective filling and sealing of the crack. The addition of nano-alumina not only improves the overall performance of the material, but also enhances the sealing and waterproofness of the repaired structure, greatly extending the service life of the structure and reducing maintenance costs.

[0023] The introduction of polyurethane enhances the bonding strength between the repair material and the original concrete structure. Polyurethane has excellent bonding properties and can form strong chemical bonds and physical interlocks to ensure a close bond between the repair layer and the original structure, effectively preventing the repair layer from falling off due to vibration or temperature changes. This enhanced bonding not only improves the reliability of the repair, but also ensures long-term durability, avoiding the tediousness and cost of repeated maintenance after the repair. DETAILED DESCRIPTION

[0024] In view of the defects of the prior art that it is difficult to simultaneously meet the requirements of setting time, permeability and coagulation, the present invention aims to enhance the bonding performance by introducing polyurethane, and improve the microstructural strength of the material by combining nanomaterials (mainly nano-alumina), optimize the mix ratio and improve the performance, thereby creating a cement-based composite repair material with excellent fluidity, high permeability and good interface adhesion. While ensuring the adjustable setting time and fluidity, it ensures that the material can penetrate into tiny cracks and form a firm bond with the concrete structure interface to avoid recurrence of diseases. The introduction of nano-alumina can not only improve the density and wear resistance of the material, but also promote better permeability, so that the material can penetrate into the smallest part of the crack. At the same time, the elastic properties of polyurethane help the material maintain the repair effect when dealing with structural micro-deformation, increase the bonding strength between the repair area and the original structure, and achieve a long-term and stable repair effect.

[0025] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0026] Example 1

[0027] The polyurethane nano-alumina composite repair material includes the following components in parts by mass: 400 parts of cement, 80 parts of fly ash, 60 parts of silica fume, 20 parts of polyurethane, 25 parts of nano-alumina, 700 parts of sand, 4 parts of water reducer, and 170 parts of water.

[0028] The cement is 42.5 ordinary Portland cement, which has good compatibility with polycarboxylic acid water reducer.

[0029] Fly ash is Grade I, with an average particle size between 10 and 30 microns and a specific surface area greater than 500 cm 2 / g.

[0030] The mass percentage of silicon dioxide in silica ash is not less than 97%, the volcanic ash activity index is greater than 95%, and the specific surface area is greater than 21.0m 2 / g, density is 2.20g / cm 3 .

[0031] The polyurethane is a cationic water-based polyurethane with a viscosity of 0.1 to 1 Pa·s and a solid content of 40% to 50%.

[0032] The particle size of nano-alumina is 5 to 10 nm.

[0033] The sand is fine quartz sand, mesh size is 200 mesh, and the bulk density is less than 1500kg / m 3 .

[0034] The water reducing agent is a polycarboxylic acid-based water reducing agent, with a solid content greater than 30%, a pH value of about 7.5, and a water reduction rate of more than 30%.

[0035] The preparation method of the polyurethane nano-alumina composite repair material is as follows:

[0036] (1) Mix polyurethane with 20% to 30% water and stir at 45 rpm for 5 minutes to form a uniform polyurethane solution.

[0037] (2) Add cement, fly ash, silica fume, nano-alumina and sand into the mixer according to the designed proportion and stir at 45 r / min for 5 min to ensure that all dry ingredients are thoroughly mixed.

[0038] (3) First, add the polyurethane solution and the remaining water into the mixer where the materials have been mixed, stir at 45 r / min for 3 min to ensure uniform mixing, then add the water reducer and stir at 150 r / min for 5 min to form a uniform slurry.

[0039] Example 2

[0040] The polyurethane nano-alumina composite repair material includes the following components in parts by mass: 350 parts of cement, 60 parts of fly ash, 40 parts of silica fume, 15 parts of polyurethane, 20 parts of nano-alumina, 600 parts of sand, 6 parts of water reducer, and 190 parts of water.

[0041] The selection requirements and preparation methods of each component are the same as those in Example 1.

[0042] Comparative Example 1

[0043] The polyurethane repair material includes the following components in parts by mass: 350 parts of cement, 60 parts of fly ash, 40 parts of silica fume, 15 parts of polyurethane, 600 parts of sand, 6 parts of water reducer, and 190 parts of water.

[0044] The selection requirements and preparation methods of each component are the same as those in Example 1.

[0045] Comparative Example 2

[0046] The nano-alumina repair material includes the following components in parts by mass: 350 parts of cement, 60 parts of fly ash, 40 parts of silica fume, 25 parts of nano-alumina, 600 parts of sand, 6 parts of water reducer, and 190 parts of water.

[0047] The selection requirements of each component are the same as those in Example 1, and the preparation method does not include the preparation of the polyurethane solution compared with Example 1.

[0048] Comparative Example 3

[0049] The repair material includes the following components in parts by mass: 350 parts of cement, 60 parts of fly ash, 40 parts of silica fume, 18 parts of water glass, 600 parts of sand, 6 parts of water reducing agent, and 190 parts of water.

[0050] The selection requirements and preparation methods of the components other than water glass are the same as those in Example 1. Water glass is commercially available sodium silicate water glass with a density of 1.4-1.5 g / cm 3 , modulus 2.6, viscosity 30-50mPa·s.

[0051] The preparation method of the repair material is as follows:

[0052] (1) mixing water glass and 30% water with stirring to obtain a water glass mixed solution;

[0053] (2) mixing cement, fly ash, silica fume, nano-alumina and sand;

[0054] (3) adding the remaining 70% of water and a water reducing agent and stirring to obtain a cement paste;

[0055] (4) Mixing the mixed solution obtained in step (1) and the cement slurry obtained in step (3) and rapidly stirring them to obtain a cement-water glass repair material.

[0056] Table 1 Performance indicators of Examples 1 to 3 and Comparative Examples 1 and 2

[0057]

[0058] The expansion, compressive strength, adhesion, setting time and impermeability grade of Examples 1 to 2 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 1. Compared with the comparative examples, Examples 1 and 2 performed well in multiple performance indicators. In particular, Example 1 was superior to the comparative example in expansion, compressive strength, adhesion, setting time and impermeability grade, indicating its excellent fluidity, rapid hardening ability and efficient penetration performance, which is suitable for emergency repair needs. At the same time, Example 2 adjusted the proportion composition compared with Example 1, so that the setting time was adjusted from 40min in Example 1 to 90min, but the compressive strength and adhesion were still maintained at a high level, ensuring the long-term stability and durability of the repair material. These improvements are attributed to the addition of polyurethane and nano-alumina. The combination of these two materials significantly improves the bonding strength and waterproof performance of the repair material, making the material show significant advantages in the maintenance and reinforcement of key infrastructure such as subway stations. In Comparative Example 1, only polyurethane was added, which maintained a certain degree of adhesion but other properties decreased; in Comparative Example 2, only nano-alumina was added, although it had a high expansibility, other properties could not meet the requirements. Comparative Example 3 is a traditional cement-water glass double slurry repair material, except for the shorter setting time, the other properties are much lower than those of Example 1 and Example 2. By comparing the examples and comparative examples, it can be found that in addition to enhancing the adhesion and permeability of polyurethane and nano-alumina, the two work together to improve the overall performance of the repair material.

[0059] Example 3

[0060] The polyurethane nano-alumina composite repair material includes the following components in parts by mass: 350 parts of cement, 60 parts of fly ash, 40 parts of silica fume, 15 parts of polyurethane, 20 parts of nano-alumina, 600 parts of sand, 4 parts of water reducer, and 170 parts of water.

[0061] The cement is 42.5 ordinary Portland cement, which has good compatibility with polycarboxylic acid water reducer.

[0062] Fly ash is Grade I, with an average particle size between 10 and 30 microns and a specific surface area greater than 500 cm 2 / g.

[0063] The mass percentage of silicon dioxide in silica ash is not less than 97%, the volcanic ash activity index is greater than 95%, and the specific surface area is greater than 21.0m 2 / g, density is 2.10g / cm 3 .

[0064] The polyurethane is a cationic water-based polyurethane with a viscosity of 0.1 to 1 Pa·s and a solid content of 40% to 50%.

[0065] The particle size of nano-alumina is 5 to 10 nm.

[0066] The sand is fine quartz sand, mesh size is 200 mesh, and the bulk density is less than 1500kg / m 3 .

[0067] The water reducing agent is a polycarboxylic acid-based water reducing agent, with a solid content greater than 30%, a pH value of about 7.5, and a water reduction rate of more than 30%.

[0068] The preparation method of the polyurethane nano-alumina composite repair material is as follows:

[0069] (1) Mix polyurethane with 20% to 30% water and stir at 45 rpm for 3 minutes to form a uniform polyurethane solution.

[0070] (2) Add cement, fly ash, silica fume, nano-alumina and sand into the mixer according to the designed proportion and stir at 45 r / min for 3 min to ensure that all dry ingredients are thoroughly mixed.

[0071] (3) First, add the polyurethane solution and the remaining water into the mixer where the materials have been mixed, stir at 45 r / min for 3 min to ensure uniform mixing, then add the water reducer and stir at 140 r / min for 4 min to form a uniform slurry.

[0072] Example 4

[0073] The polyurethane nano-alumina composite repair material includes the following components in parts by mass: 400 parts of cement, 80 parts of fly ash, 60 parts of silica fume, 20 parts of polyurethane, 25 parts of nano-alumina, 700 parts of sand, 6 parts of water reducer, and 190 parts of water.

[0074] The cement is 42.5 ordinary Portland cement, which has good compatibility with polycarboxylic acid water reducer.

[0075] Fly ash is Grade I, with an average particle size between 10 and 30 microns and a specific surface area greater than 500 cm 2 / g.

[0076] The mass percentage of silicon dioxide in silica ash is not less than 97%, the volcanic ash activity index is greater than 95%, and the specific surface area is greater than 21.0m 2 / g, density is 2.30g / cm 3 .

[0077] The polyurethane is a cationic water-based polyurethane with a viscosity of 0.1 to 1 Pa·s and a solid content of 40% to 50%.

[0078] The particle size of nano-alumina is 5 to 10 nm.

[0079] The sand is fine quartz sand, mesh size is 200 mesh, and the bulk density is less than 1500kg / m 3 .

[0080] The water reducing agent is a polycarboxylic acid-based water reducing agent, with a solid content greater than 30%, a pH value of about 7.5, and a water reduction rate of more than 30%.

[0081] The preparation method of the polyurethane nano-alumina composite repair material is as follows:

[0082] (1) Mix polyurethane with 20% to 30% water and stir at 60 r / min for 5 minutes to form a uniform polyurethane solution.

[0083] (2) Add cement, fly ash, silica fume, nano-alumina and sand into the mixer according to the designed proportion and stir at 60 r / min for 5 min to ensure that all dry ingredients are thoroughly mixed.

[0084] (3) First, add the polyurethane solution and the remaining water into the mixer where the materials have been mixed, stir at 60 r / min for 3 min to ensure uniform mixing, then add the water reducer and stir at 160 r / min for 5 min to form a uniform slurry.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polyurethane nano-alumina composite repair material, characterized in that: The invention comprises the following components in parts by weight: 350-400 parts of cement, 60-80 parts of fly ash, 40-60 parts of silica fume, 15-20 parts of polyurethane, 20-25 parts of nano-alumina, 600-700 parts of sand, 4-6 parts of water reducing agent and 170-190 parts of water.

2. The polyurethane nano-alumina composite repair material according to claim 1, characterized in that: The cement includes 42.5 ordinary Portland cement.

3. The polyurethane nano-alumina composite repair material according to claim 1, characterized in that: The fly ash is of grade I, with an average particle size of 10 to 30 μm and a specific surface area of ​​more than 500 cm 2 / g.

4. The polyurethane nano-alumina composite repair material according to claim 1, characterized in that: The mass percentage of silicon dioxide in the silica ash is not less than 97%, the volcanic ash activity index is greater than 95%, and the specific surface area is greater than 21.0m 2 / g, density is 2.10~2.30g / cm 3 .

5. The polyurethane nano-alumina composite repair material according to claim 1, characterized in that: The polyurethane is a cationic water-based polyurethane with a viscosity of 0.1-1 Pa·s and a solid content of 40%-50%.

6. The polyurethane nano-alumina composite repair material according to claim 1, characterized in that: The particle size of the nano-alumina is 5-10 nm.

7. The polyurethane nano-alumina composite repair material according to claim 1, characterized in that: The sand is fine quartz sand with a mesh size of 200 and a bulk density of less than 1500 kg / m 3 .

8. The polyurethane nano-alumina composite repair material according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid-based water reducing agent, with a solid content greater than 30%, a pH value of 7 to 8, and a water reducing rate of more than 30%.

9. A polyurethane nano-alumina composite repair material as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Mixing polyurethane with 20% to 30% of water to form a polyurethane solution; S2, mixing cement, fly ash, silica fume, nano-alumina and sand to obtain a mixed dry component; S3. Add the polyurethane solution and the remaining water to the mixed dry ingredients, stir evenly, then add a water reducing agent and stir to obtain a polyurethane nano-alumina composite repair material.

10. The preparation method according to claim 9, characterized in that: In step S1, the mixture is stirred at 45 to 60 r / min for 3 to 5 min. In step S2, the mixture is stirred at 45 to 60 r / min for 3 to 5 min. In step S3, the mixture is stirred at 45 to 60 r / min for 2 to 3 min until the mixture is uniformly stirred. Then, a water reducing agent is added and stirred at 140 to 160 r / min for 4 to 5 min.

Images