Blended fiber reactive powder concrete, preparation method thereof and preparation method of finished product

Abstract

The invention relates to fiber-doped reactive powder concrete which is characterized in that long steel fibers, short steel fibers, end hook fibers and glass fibers are doped into the concrete, the doping amount of the long steel fibers is 0-1.5% of the volume of the concrete, the doping amount of the short steel fibers is 0.5-2% of the volume of the concrete, the doping amount of the end hook fibers is 0-2% of the volume of the concrete, and the doping amount of the glass fibers is 0.5-2% of the volume of the concrete. The doping amount of the glass fibers is 0-1% of the volume of the concrete. The invention further relates to a preparation method of the fiber-blended reactive powder concrete and a preparation method of a fiber-blended reactive powder concrete finished product. The fiber is reasonable in proportion and high in feasibility, the mechanical property of the prepared mixed fiber reactive powder concrete can be enhanced, and the mixed fiber reactive powder concrete is particularly suitable for steel fiber concrete with the high breaking strength requirement and belongs to the technical field of novel RPC materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new RPC materials, in particular to a mixed fiber reactive powder concrete and a preparation method thereof, and further relates to a preparation method of a mixed fiber reactive powder concrete product. BACKGROUND

[0002] Reactive powder concrete (RPC) is a new type of ultra-high performance concrete. Steel fiber reactive powder concrete is a concrete composite material formed by adding an appropriate amount of steel fibers to RPC. Adding steel fibers to concrete can significantly enhance its crack resistance, tensile properties and ductility; it can also enhance the fracture toughness. This is crucial for reactive powder concrete (RPC). Compared with traditional concrete, steel fiber reactive powder concrete has significantly higher mechanical properties. At the same time, the cement content of RPC is only half of that of ordinary concrete, and the carbon dioxide emissions during its production are only about 50% of that of ordinary concrete, which makes it very suitable for the development needs of green buildings. Because of these characteristics, RPC plays a key role in the fields of housing construction, aerospace engineering and nuclear power plant engineering.

[0003] At present, there are many studies on the influence of mixed fibers of different types on the mechanical properties of reactive powder concrete, but the influence of mixed steel fibers of different lengths on the mechanical properties of reactive powder concrete is relatively lacking, so it is urgent to prepare a mixed fiber reactive powder concrete with better mechanical properties. SUMMARY

[0004] In view of the technical problems existing in the prior art, the purpose of the present application is to provide a mixed fiber reactive powder concrete and a preparation method thereof.

[0005] Another purpose of the present application is to provide a preparation method of a mixed fiber reactive powder concrete product.

[0006] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions: A mixed fiber reactive powder concrete, in which long steel fibers, short steel fibers, end hook fibers and glass fibers are mixed in the concrete, the long steel fiber mixing amount is 0-1.5% of the volume of the concrete, the short steel fiber mixing amount is 0.5-2% of the volume of the concrete, the end hook fiber mixing amount is 0-2% of the volume of the concrete, and the glass fiber mixing amount is 0-1% of the volume of the concrete.

[0007] As a preferred, the concrete raw materials include cement, silica fume, mineral powder, fly ash, machine-made sand, water and water reducing agent.

[0008] As a preferred, the cement is P·Ⅱ42.5R, and the fly ash is grade I fly ash.

[0009] As a preferred, the water reducing agent is polycarboxylic acid high performance water reducing agent, the water reducing rate is 28%, and the density is 1.043 g / cm 3 .

[0010] As a preferred, the long steel fiber specification is 19 mm, and the short steel fiber specification is 13 mm.

[0011] As a preferred, the long steel fiber incorporation amount is 1% of the concrete volume, and the short steel fiber incorporation amount is 1% of the concrete volume.

[0012] A preparation method of a mixed fiber reactive powder concrete, comprising the following steps: a. First, the reactive powder concrete dry mixture is weighed and poured into a single-shaft concrete mixer, and the mixed fibers including long steel fibers, short steel fibers, end-hook fibers and glass fibers are added to the grid screen placed above the inlet of the concrete mixer, so that the mixed fibers are uniformly scattered into the concrete mixer; b. After all the mixtures are uniformly stirred, the measured amount of the admixture and water are added, and the stirring is continued.

[0013] As a preferred, in step a, the stirring time is 90 seconds; in step b, after the admixture and water are added, the stirring time is 3 minutes.

[0014] As a preferred, in step b, a part of the water is poured into the concrete mixer after washing the amount of the admixture.

[0015] A preparation method of a mixed fiber reactive powder concrete product, comprising the following steps: (1) A template is made, and a release agent is applied to the bottom of the template before pouring; (2) The mixed fiber reactive powder concrete described in any one of claims 1-6 is made by using a concrete mixer; (3) After the concrete mixing is completed, it is poured into the template, and the pouring is vibrated at the same time; finally, the top surface is smoothed to make a mixed fiber reactive powder concrete semi-finished product, and the mixed fiber reactive powder concrete product is obtained after the semi-finished product is cured for 7-8 days.

[0016] The principle of the present application is that different types of fibers such as long steel fibers, short steel fibers, end-hooked fibers and glass fibers are mixed in concrete, and a plurality of implementation schemes are constructed by controlling the fiber volume fraction and proportion combination. The dosage of each type of fiber is controlled in the range of 0% to 2% of the total volume of concrete to form different length effects, interface bonding effects and synergistic reinforcement mechanisms. Combined with a plurality of test data, the different fiber combinations are compared and verified in terms of flexural strength, impact resistance and toughness improvement to obtain the end value, median value and optimal mixing range. By introducing a multi-fiber synergistic system, the crack propagation behavior and energy dissipation capacity of the reactive powder concrete are improved, and the damage resistance of the material under complex stress conditions is improved.

[0017] The present application has the following advantages: 1. The present application introduces a composite mixing system of long steel fibers, short steel fibers, end-hooked fibers and glass fibers, and each type of fiber has differences in length scale, interface bonding and fracture mechanism. Short fibers inhibit the formation of microcracks in the early stage, end-hooked fibers enhance the pull-out resistance, long fibers provide bridging action in the crack propagation stage, and glass fibers improve deformation compatibility. Through the synergistic effect of multiple fibers, the crack resistance, bending resistance and energy dissipation performance of concrete can be significantly improved.

[0018] 2. In the RPC, different lengths of steel fibers are appropriately mixed to reduce the total dosage of steel fibers.

[0019] 3. By mixing different lengths of steel fibers, the strength of the material can be effectively improved, and the cost can be reduced.

[0020] 4. Compared with single fibers, the mixing of long steel fibers and short steel fibers can improve the flexural strength of concrete. The high crack resistance provided by short steel fibers and the bending resistance provided by long steel fibers are complementary, and the combination of the two can make the concrete exhibit excellent tensile, bending and crack resistance under various load conditions.

[0021] 5. The addition of long and short steel fibers and other components has a linkage effect, which can produce a more optimal effect than when they are added separately. For example, in actual construction, short steel fibers can control the generation of microcracks in the early stage, while long steel fibers can provide bridging action when the crack develops to a larger size. The synergistic effect of the two helps to improve the durability and comprehensive mechanical properties of concrete.

[0022] 6. The fiber ratio of the present application is reasonable and highly feasible, which can enhance the mechanical properties of the prepared mixed fiber reactive powder concrete, and is particularly suitable for steel fiber concrete with high flexural strength requirements.

[0023] 7. The technical system obtained by the present application has the characteristics of adjustable proportion and feasible implementation, and can provide a basis for the impact resistance, blast resistance and structural safety design of high-performance concrete. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 This is a schematic diagram of the failure of the flexural specimen.

[0025] Figure 2 This is a schematic diagram of the failure of a cubic compression specimen. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to specific embodiments.

[0027] Explanation of the source of raw materials used in the examples: The cement used is P.II42.5R cement produced by Yingde Conch Cement Co., Ltd.; the fly ash used is Class F Grade I fly ash produced by Yangxi Haibin Power Development Co., Ltd.; the water-reducing agent used is polycarboxylate-based high-performance water-reducing agent produced by Guangdong Hongqiang New Materials Co., Ltd.

[0028] Example 1 A fiber-reinforced reactive powder concrete comprises long steel fibers, short steel fibers, end-hooked fibers, and glass fibers incorporated into the concrete. The amounts of long steel fibers, short steel fibers, end-hooked fibers, and glass fibers are all 1% of the concrete volume. The long steel fibers have a diameter of 19 mm, and the short steel fibers have a diameter of 13 mm. The fiber volume fraction refers to the proportion of the total concrete volume and is included in the overall mix design.

[0029] Concrete raw materials include cement, silica fume, mineral powder, fly ash, manufactured sand, water, and a water-reducing agent. The cement is P·Ⅱ42.5R, the fly ash is Grade I fly ash, and the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent with a water reduction rate of 28% and a density of 1.043 g / cm³. 3 In this embodiment, per 1m 3 The concrete contains 720kg of cement, 206kg of silica fume, 93kg of mineral powder, 90kg of Class I fly ash, 1000kg of manufactured sand, 183kg of water, and 26kg of water-reducing agent as basic materials.

[0030] A method for preparing fiber-reinforced active powder concrete, comprising the following steps: (1) Make a template, using a flat steel plate as the base plate, and use steel strips of different sizes to fix it around the perimeter. Apply a release agent to the bottom of the template before pouring.

[0031] (2) The following are the specific steps for preparing fiber-reinforced active powder concrete using a concrete mixer: a. First, the active powder concrete dry mixture is weighed and poured into a single-shaft concrete mixer for 90 seconds. The mixed fibers, including long steel fibers, short steel fibers, end-hook fibers, and glass fibers, are added to the grid screen placed above the inlet of the concrete mixer to ensure uniform distribution of the mixed fibers in the concrete mixer.

[0032] b. After the mixture is well mixed, the measured amount of admixture and water is added, and the mixing is continued for another 3 minutes. When adding water, a portion of the water is used to rinse the measuring cylinder containing the admixture, and the remaining water is directly added to the concrete mixer.

[0033] (3) After the concrete is mixed, it is poured into the formwork and vibrated while pouring. Finally, the top surface is smoothed to produce a mixed fiber active powder concrete semi-finished product. After curing for 7-8 days, the mixed fiber active powder concrete product is obtained.

[0034] Example Two A mixed fiber active powder concrete is prepared by incorporating short steel fibers, end-hook fibers, and glass fibers into the concrete. The short steel fibers are added at a volume of 2% of the concrete, the end-hook fibers at a volume of 1.5% of the concrete, and the glass fibers at a volume of 0.5% of the concrete. The short steel fibers have a specification of 13mm.

[0035] In step (2)a, the active powder concrete dry mixture is first weighed and poured into a single-shaft concrete mixer for 90 seconds. The mixed fibers, including short steel fibers, end-hook fibers, and glass fibers, are added to the grid screen placed above the inlet of the concrete mixer to ensure uniform distribution of the mixed fibers in the concrete mixer.

[0036] This example does not mention the parts of Example One.

[0037] Performance Test: The instrument for the cube compressive strength test is an electro-hydraulic servo pressure testing machine. According to the standard "GBT 50081-2019 Concrete Physical and Mechanical Properties Test Methods Standard" and "Ultra-high Performance Concrete Basic Properties and Test Methods", the size of the standard cube test specimen is 100mm x 100mm x 100mm, and there are 6 test specimens in each group. The average value of the test specimens with a deviation of less than 15% from the average value is taken as the measured value.

[0038] The flexural strength is an index to measure the toughness of the test specimen. The test uses a four-point bending loading method, with the upper and lower support positions on the surface of the test specimen, and the molded side as the contact surface. The upper pressure head distance is adjusted to 100mm, and the lower pressure head distance is adjusted to 300mm, leaving 50mm at both ends of the test specimen.

[0039] The test uses a stress loading control method, with a loading speed of 0.05MPa / s.

[0040] According to the standard "GBT 50081-2019 Concrete Physical and Mechanical Properties Test Method Standard" and "Ultra High Performance Concrete Basic Performance and Test Method", the specimen size is 100mmx100mmx400mm, and each group has 6-8 specimens. The average value of the specimen with a deviation of less than 15% from the average value and a broken section within the two concentrated loads is taken as the measured value. The specimens participating in the average value calculation should not be less than 4.

[0041] According to the obtained material performance test results, the results are as follows.

[0042]

[0043] As can be seen from the table, the short fiber of the mixed fiber reactive powder concrete prepared by the example of the present application is better than the long fiber in improving the compressive performance of RPC; the long fiber is better than the short fiber in improving the flexural performance of RPC; the flexural strength of the 1% of the concrete volume of the 13mm short steel fiber and the 1% of the concrete volume of the 19mm long steel fiber is enhanced relative to the 2% of the concrete volume of the 13mm short steel fiber, and the average flexural strength is increased by 18.7%. It can be found that the mixed fiber reactive powder concrete has the best flexural capacity when the mixed fiber is 1% long steel fiber and 1% short steel fiber. Therefore, the mixed fiber reactive powder concrete has high flexural strength, saves materials, has high application value, and has strong popularization.

[0044] In addition to the above-mentioned manner, the present application can be mixed with fibers in other existing reactive powder concretes. These transformation modes all belong to the protection scope of the present application.

[0045] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes, and all shall be included in the protection scope of the present application.

Claims

1. A hybrid fiber reinforced cementitious composite, characterized by, The long steel fiber, the short steel fiber, the end hook fiber and the glass fiber are mixed in the concrete, the long steel fiber mixing amount is 0-1.5% of the concrete volume, the short steel fiber mixing amount is 0.5-2% of the concrete volume, the end hook fiber mixing amount is 0-2% of the concrete volume, and the glass fiber mixing amount is 0-1% of the concrete volume.

2. A hybrid fiber reinforced powder concrete according to claim 1, characterized in that, The concrete raw materials include cement, silica fume, mineral powder, fly ash, machine-made sand, water and water reducing agent.

3. A hybrid fiber reinforced powder concrete according to claim 2, characterized in that: The cement is P·Ⅱ 42.5R, and the fly ash is grade I fly ash.

4. A hybrid fiber reinforced powder concrete according to claim 2, characterized in that: The water reducing agent is a polycarboxylic acid high performance water reducing agent, with a water reducing rate of 28% and a density of 1.043 g / cm 3 .

5. A hybrid fiber reinforced powder concrete according to claim 1, characterized in that: The long steel fiber specification is 19mm, and the short steel fiber specification is 13mm.

6. A hybrid fiber reinforced powder concrete according to claim 1, characterized in that: The long steel fiber mixing amount is 1% of the concrete volume, and the short steel fiber mixing amount is 1% of the concrete volume.

7. A method of producing a hybrid fiber reinforced powder concrete according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: a. First, the active powder concrete dry mixture is weighed and poured into a single-shaft concrete mixer, and the mixed fibers including long steel fibers, short steel fibers, end hook fibers and glass fibers are added to the grid screen above the concrete mixer inlet, so that the mixed fibers are evenly scattered into the concrete mixer; b. After all the mixtures are uniformly stirred, the measured amount of admixture and water is added, and the stirring is continued.

8. A method of manufacturing a hybrid fiber reinforced powder concrete according to claim 7, characterized in that: In step a, the stirring time is 90 seconds; in step b, after the admixture and water are added, the stirring time is 3 minutes.

9. A method of manufacturing a hybrid fiber reinforced powder concrete according to claim 7, characterized in that: In step b, a part of the water is used to rinse the amount of the admixture cylinder and then poured into the concrete mixer.

10. A method for producing a finished product of a hybrid fiber reinforced reactive powder concrete, characterized by, The method comprises the following steps: (1) making a formwork, and coating a release agent on the bottom of the formwork before pouring; (2) using a concrete mixer to make the mixed fiber active powder concrete according to any one of claims 1-6; (3) pouring the concrete into the formwork after the concrete mixing is completed, and vibrating while pouring; finally, the top surface is smoothed to make a mixed fiber active powder concrete semi-finished product, and the mixed fiber active powder concrete finished product is obtained after the semi-finished product is maintained for 7-8 days.

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