Concrete material for building

Abstract

The invention provides a concrete material for a building. The concrete material is prepared from the following raw materials in parts by weight: 400 to 600 parts of cement, 2 to 5 parts of a water reducing agent, 600 to 800 parts of coarse aggregate, 300 to 500 parts of fine aggregate, 5 to 10 parts of fly ash, 10 to 80 parts of silica fume, 5 to 15 parts of composite modified fiber and 100 to 150 parts of water, the composite modified fiber comprises modified coconut fiber, modified cotton stalk fiber and modified polypropylene fiber in a mass ratio of 1: (0.5-1): (2-3). By selecting specific fibers and limiting the usage amount of the fibers, the fiber compound can be better fused with other components such as cement, and the performance of the concrete material is further improved.

Description

Technical Field

[0001] The present application belongs to the field of building materials, and specifically relates to a concrete material for construction. Background Art

[0002] Concrete is mainly an artificial stone made of gravel, sand, gel material, water, admixtures and additives in a certain proportion, which is mixed evenly, vibrated to make it dense, and cured to harden.

[0003] With the acceleration of urbanization, there are more and more buildings with large spans, high strength and complex structures, and the requirements for concrete properties are getting higher and higher. Prefabricated and assembled building structures are becoming more and more mainstream in the construction industry. Prefabricated concrete components must be transported long distances after being produced in factories. This form of construction places higher requirements on the crack resistance and stability of the concrete itself.

[0004] The cement matrix is ​​brittle, has low tensile strength and strain capacity, and high-strength concrete has cracks. In order to solve the generation and development of cracks in concrete, fiber materials such as polymer fibers, metal fibers, plant fibers, etc. are added to the concrete to improve the performance of high-strength concrete. This can not only prevent the expansion of concrete cracks, but also improve the tensile strength and toughness of cement-based composite materials.

[0005] When adding fiber materials, their disordered state and water absorption will, to a certain extent, hinder the fusion of fibers with other concrete components such as cement and reduce fluidity; and there will be agglomeration between fibers. How to improve the workability of concrete and the uniform dispersion of fibers so that fibers can play a better role in concrete has not been well solved at present. Summary of the invention

[0006] In order to solve the above problems, the present application proposes a concrete material for construction, comprising the following raw materials in parts by weight: 400-600 parts of cement, 2-5 parts of water reducing agent, 600-800 parts of coarse aggregate, 300-500 parts of fine aggregate, 5-10 parts of fly ash, 10-80 parts of silica fume, 5-15 parts of composite modified fiber, and 100-150 parts of water;

[0007] The composite modified fiber comprises modified coconut shell fiber, modified cotton stalk fiber and modified polypropylene fiber, and the mass ratio thereof is 1:(0.5-1):(2-3).

[0008] The cement used in this application is common commercially available silicate cement.

[0009] The cotton stalk fiber used in the present application is extracted from the stems of cotton plants and contains about 40-50% cellulose. The cotton stalk fiber in the present application is Shandong upland cotton stalk, which is obtained after soaking-crushing-skinning-beating-washing-drying.

[0010] The coconut shell fiber used in the present application is obtained by soaking coconut shell in sodium hydroxide solution to remove pectin and wax, then washing with clean water and air-drying to obtain the coconut shell fiber, wherein the cellulose content of the coconut shell fiber is 40% and the lignin content is 45%.

[0011] The advantages of adding coconut shell fiber, cotton stalk fiber and polypropylene to concrete materials mainly include: 1. It can enhance crack resistance, effectively inhibit the plastic shrinkage and drying shrinkage of concrete, and reduce the occurrence of cracks; 2. Improve the toughness of concrete, making it less likely to break when subjected to impact or vibration; 3. Improve tensile strength; 4. Coconut shell fiber, as a natural recycled material, reduces the consumption of industrial fibers and conforms to the concept of environmental protection; 5. Improve durability. Coconut shell fiber has certain corrosion resistance and resistance to microbial erosion, which helps to extend the service life of concrete.

[0012] Preferably, the modified cotton stalk fiber has a length of 5-10 mm and a fineness of 2-4 mm; the modified coconut shell fiber has a length of 16-20 mm and a fineness of 100-200 μm; the modified polypropylene fiber has a length of 12-15 mm and a fineness of 1-2 mm.

[0013] The fineness of the fiber in the present invention refers to the diameter of a single fiber.

[0014] Preferably, cellulose nano whiskers are dispersed in a copper ammonia solvent until the cellulose nano whiskers are completely dissolved, and nano copper ammonia cellulose hydrosol is obtained after aging; coconut shell fiber, cotton stalk fiber, and polypropylene fiber are immersed in the nano copper ammonia cellulose hydrosol in batches for ultrasonic treatment, and modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber are obtained after drying.

[0015] The copper ammonia solvent in the present application is prepared using a conventional method, such as dissolving copper sulfate in deionized water and stirring until dissolved, slowly adding ammonia water to form a dark blue copper ammonia complex solution, and stirring until uniform.

[0016] In order to make the cellulose nano whiskers better dissolve in the copper ammonia solvent, an appropriate amount of dispersant, such as urea and sodium hydroxide, can be added.

[0017] Preferably, the concentration of the nano-cuprammonium cellulose hydrosol is 0.5-1.5 mol / L; and the particle size of the cellulose nano whiskers is 100-150 nm.

[0018] Preferably, the modified coconut shell fiber, modified cotton stalk fiber and modified polypropylene fiber are immersed in a mixed solution of tetraethyl orthosilicate and ethanol, and then the three modified fibers are taken out and placed in the reaction solution for reaction at 30-60° C. for 10-50 min, and then dried to obtain a composite modified fiber after secondary modification.

[0019] Preferably, in the mixed solution of ethyl orthosilicate and ethanol, the content of ethyl orthosilicate is 60-80%;

[0020] The reaction solution is a mixed solution of ethanol, water, a pH regulator and a dispersant, the pH regulator is ammonia water or hexamethylenetetramine, and the pH of the reaction solution is adjusted to 9-11; the mass ratio of ethanol to water is (5-7):1;

[0021] The dispersant is one of potassium chloride, sodium chloride or lithium chloride, and the content of the dispersant is 0.5% to 2% of the mass of the reaction solution.

[0022] Preferably, the water reducer is a polycarboxylic acid water reducer or an aminosulfonate water reducer.

[0023] Preferably, the coarse aggregate is ceramsite, crushed stone or pebble, and the particle size is 10-20 mm.

[0024] Preferably, the fine aggregate is ceramsite sand, river sand or quartz sand, and the particle size is 0.2-2 mm.

[0025] Preferably, the coconut shell fiber, cotton stalk fiber and polypropylene fiber are subjected to a fiber pretreatment step before being immersed in the nano-cuprammonium cellulose hydrosol, wherein the fiber pretreatment step comprises placing the three fibers in a 1-3% sodium hydroxide solution at 30-50° C. for 10-20 minutes, then rinsing with clean water and drying.

[0026] This application can bring the following beneficial effects:

[0027] 1. The present application adds coconut shell fiber, cotton stalk fiber and polypropylene fiber to concrete materials, which can not only improve the crack resistance, toughness, tensile strength and durability of concrete; by selecting specific fibers and limiting the amount of fibers used, the fiber composite can be better integrated with cement and other ingredients;

[0028] 2. The present application has found through experiments that the length and fineness of the fibers used are limited, and the fibers are more evenly distributed in the concrete, thus avoiding the agglomeration of the fibers, and further improving the performance of the concrete;

[0029] 3. Coating the fiber surface with copper ammonia cellulose can improve the interfacial bonding between the fiber and the concrete matrix, and enhance the mechanical properties and crack resistance. Secondly, copper ammonia has antibacterial and anti-corrosion properties, which can reduce microbial corrosion and chemical erosion and extend the life of concrete.

[0030] 4. Coating the fiber surface with cuprammonium cellulose can improve the compatibility between the fiber and cement. Nano cuprammonium cellulose hydrosol can form a uniform transition layer on the fiber surface, reduce the interface defects between the fiber and the cement matrix, and increase the bonding force; the coating can improve the wettability of the fiber surface, making it easier for cement slurry to penetrate into the fiber surface and improve the bonding strength; a stronger chemical bond can be formed between cuprammonium and cement, further improving the interfacial bonding performance; the cuprammonium coating, as a flexible transition layer, can alleviate the stress concentration between the fiber and cement and reduce the risk of cracking;

[0031] 5. The present application utilizes an in-situ polymerization method to generate nano-silicon dioxide particles in-situ on the fiber surface, forming a strong chemical bond and improving the adhesion of the coating. Secondly, it can further fill the fine gaps on the fiber surface after copper ammonia modification, making the fiber surface denser, further refining the void structure of the concrete, reducing the porosity, making the interior of the concrete more dense, making the interface transition zone more dense, reducing the penetration channels of moisture and harmful ions, and further improving the mechanical properties, durability, and frost resistance of the concrete;

[0032] 6. Nano-silicon dioxide has a large specific surface area and good dispersibility. It can be adsorbed on the fiber surface, reduce the agglomeration between fibers, and make the fibers disperse more evenly in the concrete, thereby improving the workability of the concrete;

[0033] 7. The water reducing agent, coarse aggregate, fine aggregate, fly ash and silica fume selected in this application can not only improve the performance of the concrete itself, but also better cooperate with cement and composite modified fiber.

[0034] 8. The present application uses composite modified fibers, which can greatly reduce the use of fly ash and silica fume, and can also achieve good product performance. DETAILED DESCRIPTION

[0035] The specific conditions not specified in the examples were carried out according to conventional conditions or conditions recommended by the manufacturer. All reagents and instruments used were conventional products obtained from commercial channels unless otherwise specified.

[0036] [Example 1]

[0037] The present embodiment provides a building concrete material, which is composed of the following raw materials in parts by weight: 400 parts of cement, 2 parts of polycarboxylic acid-based water-reducing agent, 800 parts of ceramsite (particle size is 10 mm), 500 parts of ceramsite sand (particle size is 0.2 mm), 10 parts of fly ash, 80 parts of silica fume, 5 parts of composite modified fiber, and 100 parts of water; wherein the composite modified fiber includes modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber, and the mass ratio is 1:0.5:2.5.

[0038] The preparation method of the composite modified fiber is as follows:

[0039] (1) Preparation of copper ammonia solvent: Weigh 80 g of copper sulfate and dissolve it in 500 mL of deionized water. Use a pipette to drop concentrated ammonia water (ammonia content 28%-29%) and stir rapidly to form a light blue copper hydroxide precipitate. When no more precipitate is produced, stop dropping ammonia water and wash the precipitate with hot distilled water (decantation method) until the washing liquid contains no sulfate to obtain a copper ammonia solvent.

[0040] (2) dispersing cellulose nano whiskers with a particle size of 100 nm in the copper ammonia solvent obtained in step (1), and aging at 30° C. for 1-2 days to prepare a nano-copper ammonia cellulose hydrosol with a concentration of 0.5 mol / L;

[0041] (3) Coconut shell fiber (length 16 mm, fineness 100 μm), cotton stalk fiber (length 5 mm, fineness 4 mm), and polypropylene fiber (length 12 mm, fineness 1 mm) are immersed in batches into the nano-cuprammonium cellulose hydrosol obtained in step (2) and ultrasonically treated for 30 minutes. After drying, modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber are obtained, respectively.

[0042] [Example 2]

[0043] The present embodiment provides a building concrete material, which is composed of the following raw materials in parts by weight: 600 parts of cement, 5 parts of polycarboxylic acid-based water-reducing agent, 600 parts of crushed stone (particle size is 20 mm), 400 parts of river sand (particle size is 2 mm), 5 parts of fly ash, 30 parts of silica fume, 15 parts of composite modified fiber, and 150 parts of water; wherein the composite modified fiber includes modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber, and the mass ratio is 1:1:3.

[0044] The preparation method of the composite modified fiber is as follows:

[0045] (1) Pretreatment of fiber raw materials: coconut shell fiber, cotton stalk fiber, and polypropylene fiber were placed in a 3% sodium hydroxide solution at 30°C for 10 min, then rinsed with clean water and dried;

[0046] (2) Preparation of copper ammonia solvent: Weigh 80 g of copper sulfate and dissolve it in 500 mL of deionized water. Use a pipette to drop concentrated ammonia water (ammonia content 28%-29%) and stir rapidly to form a light blue copper hydroxide precipitate. Stop dropping ammonia water when no more precipitate is produced. Wash the precipitate with hot distilled water (decantation method) until the washing liquid contains no sulfate to obtain a copper ammonia solvent.

[0047] (3) dispersing cellulose nano whiskers with a particle size of 150 nm in the copper ammonia solvent obtained in step (1), and aging at 30° C. for 1-2 days to prepare a nano-copper ammonia cellulose hydrosol with a concentration of 1.5 mol / L;

[0048] (4) Coconut shell fiber (length 20 mm, fineness 200 μm), cotton stalk fiber (length 10 mm, fineness 2 mm), and polypropylene fiber (length 15 mm, fineness 2 mm) are immersed in batches into the nano-cuprammonium cellulose hydrosol obtained in step (2) and ultrasonically treated for 30 minutes. After drying, modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber are obtained, respectively.

[0049] [Example 3]

[0050] The present embodiment provides a building concrete material, which is composed of the following raw materials in parts by weight: 500 parts of cement, 3 parts of aminosulfonate water reducing agent, 650 parts of pebbles (particle size is 16 mm), 300 parts of quartz sand (particle size is 1 mm), 8 parts of fly ash, 10 parts of silica fume, 6 parts of composite modified fibers, and 120 parts of water; wherein the composite modified fibers include modified coconut shell fibers, modified cotton stalk fibers, and modified polypropylene fibers, and the mass ratio is 1:1:2.

[0051] The preparation method of the composite modified fiber is as follows:

[0052] (1) Pretreatment of fiber raw materials: coconut shell fiber, cotton stalk fiber, and polypropylene fiber were placed in a 1% sodium hydroxide solution at 50°C for 20 min, then rinsed with clean water and dried;

[0053] (2) Preparation of copper ammonia solvent: Weigh 80 g of copper sulfate and dissolve it in 500 mL of deionized water. Use a pipette to drop concentrated ammonia water (ammonia content 28%-29%) and stir rapidly to form a light blue copper hydroxide precipitate. Stop dropping ammonia water when no more precipitate is produced. Wash the precipitate with hot distilled water (decantation method) until the washing liquid contains no sulfate to obtain a copper ammonia solvent.

[0054] (3) dispersing cellulose nano whiskers with a particle size of 120 nm in the copper ammonia solvent obtained in step (1), and aging at 30° C. for 1-2 days to prepare a nano-copper ammonia cellulose hydrosol with a concentration of 1.0 mol / L;

[0055] (4) Coconut shell fiber (length 18 mm, fineness 160 μm), cotton stalk fiber (length 8 mm, fineness 3 mm), and polypropylene fiber (length 13 mm, fineness 2 mm) are immersed in batches into the nano-cuprammonium cellulose hydrosol obtained in step (2) and ultrasonically treated for 30 minutes. After drying, modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber are obtained, respectively.

[0056] [Example 4]

[0057] This embodiment is a building concrete material, the raw material composition and proportion are the same as those of Example 3, the difference lies in the preparation method of the composite modified fiber, the preparation method of Example 3 is applied to modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber, and then secondary modification is performed through the following steps:

[0058] S1: immersing the obtained modified coconut shell fiber, modified cotton stalk fiber and modified polypropylene fiber in a mixed solution of tetraethyl orthosilicate and ethanol (wherein the content of tetraethyl orthosilicate is 60%), and ultrasonically treating for 30 minutes;

[0059] S2: Prepare a reaction solution with a mass ratio of ethanol to water of 5:1, add 0.5% potassium chloride by mass of the reaction solution, mix well, and adjust the pH of the solution to 9 with ammonia water;

[0060] S3: The three modified fibers in S1 are taken out and placed into the reaction solution in S2 to react at 30° C. for 50 min, and then dried to obtain the composite modified fiber after secondary modification.

[0061] [Example 5]

[0062] The difference from Example 4 is that the secondary modification preparation method of the composite modified fiber is different. The secondary modification method of this embodiment is as follows:

[0063] S1: immersing the obtained modified coconut shell fiber, modified cotton stalk fiber and modified polypropylene fiber in a mixed solution of tetraethyl orthosilicate and ethanol (wherein the content of tetraethyl orthosilicate is 70%), and ultrasonically treating for 30 minutes;

[0064] S2: prepare a reaction solution with a mass ratio of ethanol to water of 6:1, add 1% lithium chloride by mass of the reaction solution, mix well, and adjust the pH of the solution to 10 with hexamethylenetetramine;

[0065] S3: The three modified fibers in S1 are taken out and placed into the reaction solution in S2 to react at 50° C. for 30 min, and then dried to obtain the composite modified fiber after secondary modification.

[0066] [Example 6]

[0067] The difference from Example 4 is that the secondary modification preparation method of the composite modified fiber is different. The secondary modification method of this embodiment is as follows:

[0068] S1: immersing the obtained modified coconut shell fiber, modified cotton stalk fiber and modified polypropylene fiber in a mixed solution of tetraethyl orthosilicate and ethanol (wherein the content of tetraethyl orthosilicate is 80%), and ultrasonically treating for 30 minutes;

[0069] S2: Prepare a reaction solution with a mass ratio of ethanol to water of 7:1, add 2% of the mass of the reaction solution of sodium chloride, mix well, and adjust the pH of the solution to 11 with ammonia water;

[0070] S3: The three modified fibers in S1 are taken out and placed into the reaction solution in S2 to react at 60° C. for 10 min, and then dried to obtain the composite modified fiber after secondary modification.

[0071] [Example 7]

[0072] Compared with Example 4, the difference is that the method for secondary modification of the fiber is different. This example uses nano-silica sol, and the three fibers are placed in the silica sol for ultrasonication for 30 minutes. The average particle size of the nano-silica sol is 30 nm, and the silica content is 20%.

[0073] [Comparative Example 1]

[0074] Compared with Example 1, the difference is that composite fibers, namely coconut shell fibers (length 16 mm, fineness 100 μm), cotton stalk fibers (length 5 mm, fineness 4 mm), and polypropylene fibers (length 12 mm, fineness 1 mm) are added in a mass ratio of 1:0.5:2.5, and the fibers are not modified.

[0075] [Comparative Example 2]

[0076] Compared with Example 1, the difference is that the modified cotton stalk fiber is replaced by modified straw fiber, and the modification method is the same as that of Example 1.

[0077] [Comparative Example 3]

[0078] Compared with Example 1, the difference is that the modified polypropylene fiber is replaced by modified basalt fiber, and the modification method is the same as that of Example 1.

[0079] [Comparative Example 4]

[0080] Compared with Example 1, the difference is that the modified coconut shell fiber is not contained, and the composite modified fiber is composed of modified cotton stalk fiber and modified polypropylene fiber, and the mass ratio is 0.5:2.5.

[0081] [Comparative Example 5]

[0082] Compared with Example 1, the difference is that the modified cotton stalk fiber is not contained, and the composite modified fiber is composed of modified coconut shell fiber and modified polypropylene fiber, and the mass ratio is 1:2.5.

[0083] [Comparative Example 6]

[0084] Compared with Example 3, the difference is that modified polypropylene fiber is not contained, and the composite modified fiber is composed of modified coconut shell fiber and modified cotton stalk fiber, and the mass ratio is 1:1.

[0085]

Characterization

[0086] 1. Cube compressive strength test, refer to the test method in "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081). This test uses 150mm*150mm*150mm cubic test blocks, which are cured in a standard curing room at 20±2℃ and relative humidity above 95℃. After curing for 7d and 28d, the universal testing machine is used to test the compressive strength of 3 7d and 3 28d cubes. The loading speed of the universal testing machine is controlled at 0.5MPa / s-0.8MPa / s until the test block is completely destroyed and the loading is stopped. The results are expressed as average values.

[0087] 2. Flexural strength test: This test uses a test block of 100mm*100mm*400mm, with a size conversion coefficient of 0.85 between standard test blocks. It is cured in a standard curing room at 20±2℃ and a relative humidity of more than 95℃. After the test block has been cured for 28 days, the test block is taken out and its flexural strength is measured by the three-point test loading method. The loading speed of the universal testing machine is controlled at 0.5MPa / s until the test block breaks and the loading is stopped. The result is expressed as an average value.

[0088] 3. After completing the cube compressive strength test and flexural strength test, observe the cross section of the damaged test block to see whether the fibers are evenly distributed in the test block. Score the observation results, with scores ranging from 1 to 10 from uneven distribution to even distribution.

[0089]

[0090] From the data analysis in the above table, it can be seen that Examples 1-3 of the present invention use cuprammonium cellulose hydrosol to modify the fiber once, and compared with Comparative Example 1, that is, no fiber modification, the mechanical properties of the concrete samples are significantly improved; Examples 4-6 generate silica in situ on the fiber surface with a particle size of 20-40 nm. Compared with Example 3, the mechanical properties of the concrete samples are further significantly improved, especially Example 5, which has the best concrete mechanical properties.

[0091] Compared with Example 4, Example 7 coated silica on the fiber surface, and the result was far inferior to the in-situ generation of silica on the fiber surface. The reason is that, on the one hand, in-situ generation of silica can be more evenly distributed on the fiber surface, reducing the agglomeration of silica nanoparticles; on the other hand, in-situ generation of silica can fill the gaps on the fiber surface, making the fiber surface smoother and repairing the defects on the fiber surface to a certain extent.

[0092] From the concrete samples of Examples 2-6, it can be seen that the selection of fiber is also very important. The present invention selects coconut shell fiber, cotton stalk fiber, polypropylene fiber, and limits the fiber length, fineness, and fiber mass ratio, which have great technical contributions to the mechanical properties of concrete and the uniformity of fiber.

[0093] 4. Carbonation test: According to the national standard GB / T50082-2009 "Standard for test methods for long-term performance and durability of ordinary concrete", this test uses a test block of 100mm*100mm*400mm. During the carbonization process, test blocks of 3d, 7d, 14d, and 28d are taken respectively, and the splitting method is used to break them and measure the depth.

[0094]

[0095] From the data analysis in the above table, it can be seen that Examples 1-3 of the present invention utilize cuprammonium cellulose hydrosol to modify the fiber once, and compared with Comparative Example 1, which does not modify the fiber, the durability of the concrete sample is significantly improved; compared with Example 3, Examples 4-6 generate silica in situ on the fiber surface, and the durability of the concrete sample is further significantly improved, especially Example 5, which has the best concrete mechanical properties.

[0096] From the concrete samples of Examples 2-6, it can be seen that the selection of fiber is also very important. The present invention selects coconut shell fiber, cotton stalk fiber, polypropylene fiber, and limits the fiber length, fineness, and fiber mass ratio, which has a great technical contribution to the durability of concrete.

[0097] 5. Crack resistance: The crack-resistant concrete obtained after standard curing for 7 days was placed in an environment with a humidity of 90% and a temperature of 25°C for curing. Whether cracks appeared on the concrete surface was observed after 12 days and 24 days respectively.

[0098] Experiment number 12d Whether cracks occur 24d whether cracks occur Example 1 no no Example 2 no no Example 3 no no Example 4 no no Example 5 no no Example 6 no no Example 7 no no Comparative Example 1 Cracks Cracks Comparative Example 2 no no Comparative Example 3 no Cracks Comparative Example 4 no no Comparative Example 5 no no Comparative Example 6 no Cracks

[0099] From the data analysis in the above table, it can be seen from Examples 1-3 that coating cuprammonium cellulose on the fiber surface can effectively prevent cracks in concrete; from Examples 4-6, it can be seen that in-situ generation of nano-silicon dioxide particles on the fiber surface can also effectively prevent cracks in concrete; from Comparative Examples 2-6, it can be seen that the selection of specific fibers, specific ratios, and different fibers of different lengths and finenesses can effectively prevent cracks in concrete.

[0100] 6. Slump test: Use a trumpet-shaped slump bucket with an upper opening of 100mm, a lower opening of 200mm, and a height of 300mm to fill the concrete three times. After each filling, use a tamping hammer to hit the bucket wall evenly from the outside to the inside for 25 times, and smooth it after tamping. Then pull up the bucket, and the concrete will collapse due to its own weight. The slump is the height of the bucket minus the height of the highest point of the concrete after collapse, and the diameter of the concrete flow area is the expansion.

[0101]

[0102] From the data analysis in the above table, it can be seen from Examples 1-3 that coating cuprammonium cellulose on the fiber surface can improve the fluidity of concrete and the workability of concrete; from Examples 4-6, it can be seen that in-situ generation of nano-silicon dioxide particles on the fiber surface can better improve the fluidity of concrete; from Comparative Examples 2-6, it can be seen that the selection of specific fibers, specific ratios, and different fibers of different lengths and finenesses have a great influence on the fluidity of concrete and the workability between multiple components.

[0103] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0104] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A concrete material for construction, characterized in that: The raw materials include the following parts by weight: 400-600 parts of cement, 2-5 parts of water reducing agent, 600-800 parts of coarse aggregate, 300-500 parts of fine aggregate, 5-10 parts of fly ash, 10-80 parts of silica fume, 5-15 parts of composite modified fiber, and 100-150 parts of water; The composite modified fiber comprises modified coconut shell fiber, modified cotton stalk fiber and modified polypropylene fiber, and the mass ratio thereof is 1:(0.5-1):(2-3).

2. A building concrete material according to claim 1, characterized in that: The length of the modified cotton stalk fiber is 5-10 mm, and the fineness is 2-4 mm; the length of the modified coconut shell fiber is 16-20 mm, and the fineness is 100-200 μm; the length of the modified polypropylene fiber is 12-15 mm, and the fineness is 1-2 mm.

3. A building concrete material according to claim 1, characterized in that: The cellulose nano whiskers are dispersed in a copper ammonia solvent until the cellulose nano whiskers are completely dissolved, and nano-copper ammonia cellulose hydrosol is obtained after aging; coconut shell fiber, cotton stalk fiber, and polypropylene fiber are immersed in the nano-copper ammonia cellulose hydrosol in batches for ultrasonic treatment, and modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber are obtained after drying.

4. A building concrete material according to claim 3, characterized in that: The concentration of the nano cuprammonium cellulose hydrosol is 0.5-1.5 mol / L; the particle size of the cellulose nano whisker is 100-150 nm.

5. A building concrete material according to claim 3, characterized in that: The modified coconut shell fiber, modified cotton stalk fiber and modified polypropylene fiber are immersed in a mixed solution of tetraethyl orthosilicate and ethanol, and then the three modified fibers are taken out and put into the reaction solution to react at 30-60°C for 10-50 minutes, and then dried to obtain a composite modified fiber after secondary modification.

6. A building concrete material according to claim 5, characterized in that: In the mixed solution of ethyl orthosilicate and ethanol, the content of ethyl orthosilicate is 60-80%; The reaction solution is a mixed solution of ethanol, water, a pH regulator and a dispersant, the pH regulator is ammonia water or hexamethylenetetramine, and the pH of the reaction solution is adjusted to 9-11; the mass ratio of ethanol to water is (5-7):1; The dispersant is potassium chloride, sodium chloride or lithium chloride, and the content of the dispersant is 0.5% to 2% of the mass of the reaction solution.

7. A building concrete material according to claim 1, characterized in that: The water reducer is a polycarboxylic acid water reducer or an aminosulfonate water reducer.

8. The building concrete material according to claim 1, characterized in that: The coarse aggregate is ceramsite, crushed stone or pebble, and the particle size is 10-20mm.

9. The building concrete material according to claim 1, characterized in that: The fine aggregate is ceramsite sand, river sand or quartz sand, and the particle size is 0.2-2 mm.

10. The building concrete material according to claim 3, characterized in that: Before being immersed in the nano-cuprammonium cellulose hydrosol, the coconut shell fiber, cotton stalk fiber and polypropylene fiber are subjected to a fiber pretreatment step, which comprises placing the three fibers in a 1-3% sodium hydroxide solution at 30-50° C. for 10-20 minutes, then washing with clean water and drying.

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