Capsule fiber capable of reducing permeability of RPC (reactive powder concrete) and application of capsule fiber

Abstract

The invention discloses a capsule fiber capable of reducing RPC permeability and application. The capsule fiber comprises a polypropylene fiber with an inner cavity, and the inner cavity is filled with polyurethane liquid glue; the length of the capsule fiber is 12-20 mm, the diameter of an inner cavity is 1-2 mm, and the wall thickness of the capsule fiber is 0.5-1 mm. The capsule fiber provided by the invention not only can improve the strength, toughness and durability of RPC concrete, but also can fill and repair the RPC concrete when the RPC concrete generates micro-damage, and has better penetration resistance.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to capsule fiber for reducing RPC permeability and application thereof. Background Art

[0002] Ultra-High Performance Concrete (UHPC), also known as Reactive Powder Concrete (RPC), has high strength, high toughness and high durability. Because RPC has excellent mechanical properties, it can be used for the storage of air, methane and hydrogen. Although RPC has excellent mechanical properties and durability, in practical applications, the porosity and permeability of RPC are still issues that need to be further optimized. Traditional RPC improves density and microstructure by optimizing particle grading, thermal curing and other methods, but these methods still cannot fully meet the requirements for RPC's anti-permeability performance under extreme conditions. There are also some existing technologies that improve the strength of RPC by adding short steel fibers, polypropylene fibers, and basalt short fibers, and also add microcapsules containing binders for repair. The existing method not only requires the addition of short steel fibers, polypropylene fibers, basalt short fibers and microcapsules, which is more troublesome, but also the cracks in the microcapsules are difficult to control. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a capsule fiber and application for reducing the permeability of RPC. The application of the capsule fiber of the present invention can not only improve the strength, toughness and durability of RPC concrete, but also fill and repair the RPC concrete when micro-damage occurs, so as to maintain longer-term anti-permeability performance.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A capsule fiber for reducing the permeability of RPC, the capsule fiber comprising a polypropylene fiber having an inner cavity filled with polyurethane liquid glue;

[0006] The capsule fiber is 12-20 mm long, the inner cavity diameter is 1-2 mm, and the capsule fiber wall thickness is 0.5-1 mm.

[0007] Compared with the prior art, the present invention has the following beneficial effects:

[0008] 1. After adding the capsule fiber of the present invention to RPC concrete, the strength of RPC concrete is equivalent to that of RPC concrete with steel fiber added, and the permeability of RPC concrete can be increased by 10 -13 ~10 -14Moreover, when RPC concrete is slightly damaged, cracks will appear on the surface of the capsule fiber, and the polyurethane liquid glue in the inner cavity will seep out to fill the damaged space of the RPC concrete and solidify and bond, compensating for the strength loss, filling the new cracks and original pores, and maintaining longer-term anti-penetration performance.

[0009] 2. The capsule fiber of the present invention has a length of 12-20 mm, an inner cavity diameter of 1-2 mm, and a capsule fiber wall thickness of 0.5-1 mm. Firstly, it can ensure that during the preparation of RPC concrete, the capsule fiber is more easily dispersed and moved in the stirring medium, and the capsule fiber has good fluidity, so that the capsule fiber is evenly distributed in the RPC concrete, thereby ensuring the stability and reliability of the overall performance of the RPC concrete; secondly, the capsule fiber that meets the above requirements bears less pressure per unit area during the stirring and mixing process, and is also subjected to less mechanical impact and friction, and basically does not break during the stirring and mixing process, which is very important in practical applications; in addition, when the RPC concrete is slightly damaged, the capsule fiber that meets the above requirements can pull out cracks when subjected to force, ensuring that the polyurethane liquid glue in the inner cavity seeps out, fills the damaged space of the RPC concrete, compensates for the strength loss and improves the RPC anti-penetration performance.

[0010] As a preferred embodiment of the present invention, the capsule fiber is 15 mm long, the inner cavity diameter is 1 mm, and the capsule fiber wall thickness is 0.5 mm.

[0011] As a preferred embodiment of the present invention, the outer surface of the capsule fiber is formed with a serrated shape. In this scheme, the outer surface of the capsule fiber is formed with a serrated shape. First, after being stirred and mixed evenly, the capsule fiber is not easy to move and settle, and can still maintain a uniform distribution state in the RPC concrete, further ensuring the stability and reliability of the overall performance of the RPC concrete; second, the capsule fiber with a serrated surface enhances the mechanical anchoring with the concrete through its surface indentations, can be more effectively combined with the concrete matrix, improve the crack resistance and toughness of the concrete, thereby increasing the bearing capacity and durability of the concrete; third, when the RPC concrete is stressed, the outer surface is formed with a serrated capsule fiber, and the force is concentrated at the indentation. When the RPC concrete is slightly damaged, cracks can be quickly generated at the capsule fiber indentation and the polyurethane liquid glue in the inner cavity can be exuded.

[0012] The embodiment of the present invention further provides an application of capsule fiber for reducing the permeability of RPC, which is applied to prepare RPC concrete, including the following components in parts by mass:

[0013] Cement 0.8-1.2 parts;

[0014] 1.4-1.6 parts of fine aggregate;

[0015] Silica fume 0.2-0.3 parts;

[0016] Water reducing agent 0.03-0.04 parts;

[0017] 0.2-0.3 parts of water;

[0018] 0.004-0.008 parts of the capsule fiber described in any one of the above embodiments.

[0019] The scheme adopts the RPC concrete prepared by the above components, and adopts the above proportion of cement and fine aggregate to form a reasonable particle gradation, which can improve the packing density of the matrix, thereby improving the density of the mixture; silica fume has high activity and fineness, and can further fill the tiny gaps between cement and fine aggregate, improve the density and strength of concrete, and silica fume can also react with cement hydration products to improve the strength and durability of concrete; adding 0.004-0.008 parts of capsule fiber can make the RPC concrete have high strength, high toughness and high durability, and can maintain long-term anti-penetration performance; using a water reducer to reduce the water-cement ratio, improves the fluidity and strength of the cement slurry, and is more conducive to the uniform distribution of capsule fibers in the RPC concrete.

[0020] As a preferred embodiment of the present invention, the SiO2 content in the fine aggregate is greater than 90%, and quartz sand with a particle size distribution of 150-600 mm and quartz powder with a particle size of less than 44 μm are mixed in a ratio of 3:1. In this solution, the mixture of quartz sand with a particle size distribution of 150-600 mm and quartz powder with a particle size of less than 44 μm can better fill the voids inside the concrete, reduce the porosity, and improve the density and durability of the concrete. The addition of quartz powder can further refine the interface transition zone and improve the bonding force between the aggregate and the cement paste.

[0021] As a preferred embodiment of the present invention, the SiO2 content in the silica ash is greater than 90%, the average particle size is 0.1 mm, and the specific surface area is 2×10 4 ~2.5×10 4 m 2 / kg. The silica fume of this solution has small particle size and large specific surface area, and can fill the voids in the cement paste, thereby improving the compactness of the concrete, improving the resistance of the concrete to chloride ion penetration, and enhancing the durability of the concrete; SiO2 in the silica fume reacts with Ca(OH)2 produced by cement hydration to form CSH gel, which enhances hydration and improves the compressive and flexural strengths of RPC.

[0022] As a preferred embodiment of the present invention, the preparation method of RPC concrete is as follows:

[0023] S1: Weigh cement and silica fume according to the proportion, and use a forced mixer to dry mix them evenly;

[0024] S2: Weigh quartz sand and quartz powder according to the proportion, add them and dry mix them evenly;

[0025] S3: Weigh capsule fiber according to the ratio, add it and dry mix it evenly;

[0026] S4: Weigh the water reducer and water according to the proportion, mix them, add them and wet mix them evenly;

[0027] S5: After injection into the mold, immediately transfer to the curing room and control the humidity in the curing room to above 95% and the temperature to 40-45℃.

[0028] In this scheme, in the existing RPC concrete preparation method, the steps of adding capsule fiber and mixing are added, and the preparation method is simple; the humidity in the curing room is controlled to be above 95%, and the temperature is 40-45°C. Under high temperature curing, the pore volume of RPC is mainly distributed in a smaller range, and the pore structure is more uniform. At the same time, the higher temperature promotes the formation of cement hydration products, and the compressive strength and flexural strength of RPC concrete are improved, optimizing its mechanical properties. The prepared RPC concrete has high strength, high toughness and high durability, and can maintain long-term anti-permeability performance. DETAILED DESCRIPTION

[0029] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions therein are essentially used for illustration rather than for limiting the present invention.

[0030] In the following embodiments, cement, water and water reducing agent are used as follows:

[0031] Cement: Conch brand PO 52.5R Portland cement.

[0032] Water: Ordinary tap water.

[0033] Water reducing agent: polycarboxylic acid high performance water reducing agent with water reducing rate greater than 25%.

[0034] Example 1

[0035] This embodiment discloses a capsule fiber for reducing the permeability of RPC, wherein the capsule fiber comprises a polypropylene fiber having an inner cavity filled with polyurethane liquid glue; the capsule fiber is 15 mm long, the inner cavity has a diameter of 1 mm, and the capsule fiber wall thickness is 0.5 mm.

[0036] This embodiment also discloses that capsule fiber is used to prepare RPC concrete, including the following components in parts by mass:

[0037] 1 part cement

[0038] 1.51 parts of fine aggregate;

[0039] Silica fume 0.28 parts;

[0040] Water reducing agent 0.032 parts;

[0041] 0.25 parts of water;

[0042] Capsule fiber 0.005 parts.

[0043] Among them, the SiO2 content in the fine aggregate is greater than 90%, and the quartz sand with a particle size distribution of 150-600mm and the quartz powder with a particle size less than 44μm are mixed in a ratio of 3:1; the SiO2 content in the silica ash is greater than 90%, the average particle size is 0.1mm, and the specific surface area is 2×10 4 ~2.5×10 4 m 2 / kg.

[0044] The preparation method of the RPC concrete of this embodiment is as follows:

[0045] S1: Weigh cement and silica fume according to the proportion, and use a forced mixer to dry mix them evenly;

[0046] S2: Weigh quartz sand and quartz powder according to the proportion, add them and dry mix them evenly;

[0047] S3: Weigh capsule fiber according to the ratio, add it and dry mix it evenly;

[0048] S4: Weigh the water reducer and water according to the proportion, mix them, add them and wet mix them evenly;

[0049] S5: After injection into the mold, immediately transfer to the curing room and control the humidity in the curing room to above 95% and the temperature to 40-45℃.

[0050] Example 2

[0051] The difference between this embodiment and embodiment 1 is that:

[0052] The capsule fiber is 12 mm long, the inner cavity diameter is 1 mm, and the capsule fiber wall thickness is 0.5 mm.

[0053] Example 3

[0054] The difference between this embodiment and embodiment 1 is that:

[0055] The capsule fiber is 18 mm long, the inner cavity diameter is 1.5 mm, and the capsule fiber wall thickness is 0.8 mm.

[0056] Example 4

[0057] The difference between this embodiment and embodiment 1 is that:

[0058] The capsule fiber is 20 mm long, the inner cavity diameter is 2 mm, and the capsule fiber wall thickness is 1 mm.

[0059] Example 5

[0060] The difference between this embodiment and embodiment 1 is that the RPC concrete is prepared, including the following components in parts by mass:

[0061] 0.8 parts of cement;

[0062] 1.4 parts of fine aggregate;

[0063] Silica fume 0.2 parts;

[0064] 0.03 parts of water reducing agent;

[0065] 0.2 parts of water;

[0066] Capsule fiber 0.004 parts.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1 is that the RPC concrete is prepared, including the following components in parts by mass:

[0069] 1.2 parts of cement;

[0070] 1.6 parts of fine aggregate;

[0071] Silica fume 0.3 parts;

[0072] Water reducing agent 0.04 parts;

[0073] 0.3 parts of water;

[0074] Capsule fiber 0.008 parts.

[0075] The compressive strength, flexural strength, porosity and gas permeability of the RPC concrete of Examples 1-6 were tested respectively, and the results are shown in the following table:

[0076]

[0077] It can be seen from the test results in the above table that the RPC concrete prepared by the method of the present invention has excellent compressive strength and flexural strength, and at the same time has ultra-low porosity and permeability. Moreover, after the capsule fiber for reducing the permeability of RPC of the present invention is added, it can maintain longer anti-permeability performance and can be used for the storage of air, methane and hydrogen.

[0078] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A capsule fiber for reducing the permeability of RPC, characterized in that: The capsule fiber comprises a polypropylene fiber having an inner cavity, and the inner cavity is filled with polyurethane liquid glue; The capsule fiber is 12-20 mm long, the inner cavity diameter is 1-2 mm, and the capsule fiber wall thickness is 0.5-1 mm.

2. The capsule fiber for reducing RPC permeability according to claim 1, characterized in that: The capsule fiber is 15 mm long, the inner cavity diameter is 1 mm, and the capsule fiber wall thickness is 0.5 mm.

3. A capsule fiber for reducing RPC permeability according to claim 1 or 2, characterized in that: The outer surface of the capsule fiber is formed in a serrated shape.

4. An application of capsule fiber for reducing the permeability of RPC, characterized in that: Used to prepare RPC concrete, including the following components by mass: Cement 0.8-1.2 parts; 1.4-1.6 parts of fine aggregate; Silica fume 0.2-0.3 parts; Water reducing agent 0.03-0.04 parts; 0.2-0.3 parts of water; 0.004-0.008 parts of the capsule fiber according to any one of claims 1-3.

5. The use of capsule fiber for reducing RPC permeability according to claim 4, characterized in that: The SiO2 content in the fine aggregate is greater than 90%, and quartz sand with a particle size distribution of 150-600 mm and quartz powder with a particle size less than 44 μm are mixed in a ratio of 3:

1.

6. The use of capsule fiber for reducing RPC permeability according to claim 4, characterized in that: The silica ash has a SiO2 content of more than 90%, an average particle size of 0.1 mm, and a specific surface area of ​​2×10 4 ~2.5×10 4 m 2 / kg.

7. The use of capsule fiber for reducing RPC permeability according to any one of claims 4 to 6, characterized in that: The preparation method of RPC concrete is as follows: S1: Weigh cement and silica fume according to the proportion, and use a forced mixer to dry mix them evenly; S2: Weigh quartz sand and quartz powder according to the proportion, add them and dry mix them evenly; S3: Weigh capsule fiber according to the ratio, add it and dry mix it evenly; S4: Weigh the water reducer and water according to the proportion, mix them, add them and wet mix them evenly; S5: After injection into the mold, immediately transfer to the curing room and control the humidity in the curing room to above 95% and the temperature to 40-45℃.

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