A construction concrete material

Abstract

This application discloses a concrete material for construction, comprising the following raw materials in parts by weight: 400-600 parts cement, 2-5 parts water-reducing agent, 600-800 parts coarse aggregate, 300-500 parts fine aggregate, 5-10 parts fly ash, 10-80 parts silica fume, 5-15 parts composite modified fiber, and 100-150 parts water; wherein the composite modified fiber includes modified coconut shell 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 amount of fibers used, the fiber composite can better integrate with cement and other components, further improving the performance of the concrete material.

Description

Technical Field

[0001] This application belongs to the field of building materials, specifically relating to a type of concrete material for building. Background Technology

[0002] Concrete is an artificial stone material mainly composed of gravel, sand, gelling materials, water, admixtures, and additives mixed in a certain proportion, and then mixed evenly, vibrated to compact, and cured.

[0003] With the acceleration of urbanization, there are more and more buildings with large spans, high strength and complex structures, which puts higher and higher demands on the properties of concrete. Precast assembled building structures are becoming more and more mainstream in the construction industry. Precast concrete components need to be transported over long distances after being produced in the factory. This type of building places higher demands on the crack resistance and stability of the concrete itself.

[0004] Cement-based materials are brittle, have low tensile strength and strain capacity, and high-strength concrete is prone to cracking. To address the generation and development of cracks in concrete, fiber materials such as polymer fibers, metal fibers, and plant fibers are added to improve the performance of high-strength concrete. This not only prevents crack propagation in concrete but also enhances the tensile strength and toughness of cement-based composite materials.

[0005] Adding fiber materials can hinder the integration of fibers with other concrete components, such as cement, due to their disordered state and water absorption, thus reducing fluidity. Furthermore, fibers may agglomerate. Currently, there is no good solution to improve the workability of concrete and the uniform dispersion of fibers, so that fibers can play a better role in concrete. Summary of the Invention

[0006] To address the aforementioned problems, this application proposes a concrete material for construction, comprising the following raw materials in parts by weight: 400-600 parts cement, 2-5 parts water-reducing agent, 600-800 parts coarse aggregate, 300-500 parts fine aggregate, 5-10 parts fly ash, 10-80 parts silica fume, 5-15 parts composite modified fiber, and 100-150 parts water.

[0007] The composite modified fiber includes modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber, with a mass ratio of 1:(0.5-1):(2-3).

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

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

[0010] The coconut shell fiber used in this application is obtained by soaking coconut shells in sodium hydroxide solution to remove pectin and wax, then rinsing with water and air drying. The coconut shell fiber contains 40% cellulose and 45% lignin.

[0011] The advantages of adding coconut shell fiber, cotton stalk fiber, and polypropylene to concrete materials mainly include: 1. Enhancing crack resistance by effectively inhibiting plastic shrinkage and drying shrinkage of concrete, thus reducing crack formation; 2. Improving the toughness of concrete, making it less prone to breakage under impact or vibration; 3. Improving tensile strength; 4. As a natural recycled material, coconut shell fiber reduces the consumption of industrial fibers, aligning with environmental protection principles; 5. Improving durability, as coconut shell fiber possesses certain corrosion resistance and antimicrobial erosion capabilities, helping 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; and the modified polypropylene fiber has a length of 12-15 mm and a fineness of 1-2 mm.

[0013] In this invention, the fineness of the fiber refers to the diameter of a single fiber.

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

[0015] In this application, the copper ammonia solvent is prepared using conventional methods, such as dissolving copper sulfate in deionized water and stirring until dissolved, slowly adding ammonia to form a deep blue copper ammonia complex solution, and stirring until homogeneous.

[0016] To improve the dissolution of cellulose nanocrystals in copper ammonia solvent, an appropriate amount of dispersant, such as urea or sodium hydroxide, can be added.

[0017] Preferably, the concentration of the nano-copper ammonia cellulose hydrosol is 0.5-1.5 mol / L; and the particle size of the cellulose nanocrystals 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. Then, the three modified fibers are taken out and placed in the reaction solution and reacted at 30-60℃ for 10-50 minutes. After drying, the composite modified fiber after secondary modification is obtained.

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

[0020] The reaction solution is a mixture of ethanol, water, pH adjuster and dispersant. The pH adjuster is ammonia 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-reducing agent is a polycarboxylate-based water-reducing agent or an aminosulfonate water-reducing agent.

[0023] Preferably, the coarse aggregate is ceramsite, crushed stone, or pebbles with a particle size of 10-20 mm.

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

[0025] Preferably, the coconut shell fiber, cotton stalk fiber, and polypropylene fiber undergo a fiber pretreatment step before being immersed in nano-copper ammonium cellulose hydrosol. The fiber pretreatment step includes immersing the three types of fibers in a 1-3% sodium hydroxide solution at 30-50°C for 10-20 minutes, rinsing them with water, and then drying them.

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

[0027] 1. This application adds coconut shell fiber, cotton stalk fiber, and polypropylene fiber to concrete materials, which can 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 components.

[0028] 2. Through experiments, this application has found that by limiting the length and fineness of the fibers used, the fibers are more evenly distributed in the concrete, avoiding the agglomeration of fibers and further improving the performance of the concrete.

[0029] 3. Coating the fiber surface with cuprammonium cellulose can improve the interfacial bonding between the fiber and the concrete matrix, and enhance mechanical properties and crack resistance; secondly, cuprammonium cellulose has antibacterial and anti-corrosion properties, reducing microbial corrosion and chemical erosion, and extending the service life of concrete;

[0030] 4. Coating the fiber surface with cuprammonium cellulose can improve the compatibility between the fiber and cement. The nano-cuprammonium cellulose hydrosol can form a uniform transition layer on the fiber surface, reducing interfacial defects between the fiber and the cement matrix and increasing adhesion. The coating can improve the wettability of the fiber surface, making it easier for cement slurry to penetrate the fiber surface and improving the bonding strength. Cuprammonium cellulose can form stronger chemical bonds with cement, further improving the interfacial bonding performance. As a flexible transition layer, the cuprammonium cellulose coating can alleviate stress concentration between the fiber and cement and reduce the risk of cracking.

[0031] 5. This application utilizes in-situ polymerization to generate nano-silica particles on the fiber surface in situ, forming strong chemical bonds and improving the adhesion of the coating. Secondly, it can further fill the fine gaps on the surface of the copper-ammonia modified fiber, making the fiber surface more dense, further refining the void structure of the concrete, reducing porosity, making the interior of the concrete more compact, making the interface transition zone more compact, reducing the penetration channels of water and harmful ions, and further improving the mechanical properties, durability, and frost resistance of the concrete.

[0032] 6. Nano silica has a large specific surface area and good dispersibility, which can be adsorbed on the fiber surface, reducing the agglomeration between fibers and making the fibers more uniformly dispersed in concrete, thereby improving the workability of 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 concrete itself, but also better cooperate with cement and composite modified fibers.

[0034] 8. This application uses composite modified fibers, which can greatly reduce the amount of fly ash and silica fume used, and can also achieve excellent product performance. Detailed Implementation

[0035] Unless otherwise specified in the examples, the conditions were performed according to standard conditions or the manufacturer's recommendations. All reagents and instruments used were commercially available products unless otherwise specified.

[0036]

Example 1

[0037] This embodiment describes a concrete material for construction, composed of the following raw materials in parts by weight: 400 parts cement, 2 parts polycarboxylate superplasticizer, 800 parts ceramsite (particle size 10mm), 500 parts ceramsite sand (particle size 0.2mm), 10 parts fly ash, 80 parts silica fume, 5 parts composite modified fiber, and 100 parts water; wherein the composite modified fiber includes modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber, in a mass ratio of 1:0.5:2.5.

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

[0039] (1) Preparation of copper ammonia solvent: Weigh 80g of copper sulfate, dissolve it in 500mL of deionized water, add concentrated ammonia water (ammonia content 28%-29%) dropwise with a pipette, and stir rapidly to form a light blue copper hydroxide precipitate. Stop adding ammonia water when no more precipitate is formed. Wash the precipitate with hot distilled water (decanting method) until the washing solution is free of sulfate ions to obtain copper ammonia solvent.

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

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

[0042]

Example 2

[0043] This embodiment describes a concrete material for construction, composed of the following raw materials in parts by weight: 600 parts cement, 5 parts polycarboxylate superplasticizer, 600 parts crushed stone (particle size 20mm), 400 parts river sand (particle size 2mm), 5 parts fly ash, 30 parts silica fume, 15 parts composite modified fiber, and 150 parts water; wherein the composite modified fiber includes modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber in a mass ratio of 1:1:3.

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

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

[0046] (2) Preparation of copper ammonia solvent: Weigh 80g of copper sulfate, dissolve it in 500mL of deionized water, add concentrated ammonia water (ammonia content 28%-29%) dropwise with a pipette, and stir rapidly to form a light blue copper hydroxide precipitate. Stop adding ammonia water when no more precipitate is formed. Wash the precipitate with hot distilled water (decanting method) until the washing solution is free of sulfate ions to obtain copper ammonia solvent.

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

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

[0049]

Example 3

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

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

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

[0053] (2) Preparation of copper ammonia solvent: Weigh 80g of copper sulfate, dissolve it in 500mL of deionized water, add concentrated ammonia water (ammonia content 28%-29%) dropwise with a pipette, and stir rapidly to form a light blue copper hydroxide precipitate. Stop adding ammonia water when no more precipitate is formed. Wash the precipitate with hot distilled water (decanting method) until the washing solution is free of sulfate ions to obtain copper ammonia solvent.

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

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

[0056]

Example 4

[0057] This embodiment describes a building concrete material with the same raw material composition and proportions as in Example 3. The difference lies in the preparation method of the composite modified fiber. The modified fiber is applied to modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber using the preparation method of Example 3, and then undergoes secondary modification through the following steps:

[0058] S1: The modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber were immersed in a mixed solution of tetraethyl orthosilicate and ethanol (of which the content of tetraethyl orthosilicate was 60%) and ultrasonically treated for 30 min.

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

[0060] S3: Take out the three modified fibers from S1 and put them into the reaction solution in S2. React at 30℃ for 50 minutes and dry to obtain the composite modified fiber after secondary modification.

[0061]

Example 5

[0062] The difference from Example 4 lies in the secondary modification preparation method of the composite modified fiber. The secondary modification method of this example is as follows:

[0063] S1: The modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber were immersed in a mixed solution of tetraethyl orthosilicate and ethanol (the content of tetraethyl orthosilicate was 70%) and ultrasonically treated for 30 minutes.

[0064] S2: Prepare the reaction solution with an ethanol to water mass ratio of 6:1. Add 1% lithium chloride by mass of the reaction solution, mix well, and then adjust the pH of the solution to 10 with hexamethylenetetramine.

[0065] S3: Take out the three modified fibers from S1 and put them into the reaction solution in S2. React at 50°C for 30 minutes. After drying, the composite modified fiber after secondary modification is obtained.

[0066]

Example 6

[0067] The difference from Example 4 lies in the secondary modification preparation method of the composite modified fiber. The secondary modification method of this example is as follows:

[0068] S1: The modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber were immersed in a mixed solution of tetraethyl orthosilicate and ethanol (of which the content of tetraethyl orthosilicate was 80%) and ultrasonically treated for 30 min.

[0069] S2: Prepare the reaction solution with an ethanol to water mass ratio of 7:1. Add 2% sodium chloride by mass of the reaction solution, mix well, and then adjust the pH of the solution to 11 with ammonia.

[0070] S3: Take out the three modified fibers from S1 and put them into the reaction solution in S2. React at 60℃ for 10 min. After drying, the composite modified fiber after secondary modification is obtained.

[0071]

Example 7

[0072] Compared with Example 4, the difference lies in the method of secondary modification of the fibers. In this example, nano silica sol is used. The three types of fibers are placed in the silica sol and sonicated 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 are added, namely coconut shell fiber (16 mm in length and 100 μm in fineness), cotton stalk fiber (5 mm in length and 4 mm in fineness), and polypropylene fiber (12 mm in length and 1 mm in fineness), in a mass ratio of 1:0.5:2.5, without any modification treatment to the fibers.

[0075] Comparative Example 2

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

[0077] Comparative Example 3

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

[0079] Comparative Example 4

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

[0081] Comparative Example 5

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

[0083] Comparative Example 6

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

[0085] [Characteristics]

[0086] 1. Cube compressive strength test: Referencing the test methods in the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081), this test used 150mm*150mm*150mm cube specimens. These were cured in a standard curing room at 20±2℃ and relative humidity above 95%. After 7 days and 28 days of curing, a universal testing machine was used to test the compressive strength of three 7-day and three 28-day cubes. The loading speed of the universal testing machine was controlled between 0.5MPa / s and 0.8MPa / s until the specimens were completely destroyed. The results are expressed as the average value.

[0087] 2. Flexural strength test: This test uses a 100mm*100mm*400mm specimen, with a size conversion factor of 0.85 between the specimen and the standard specimen. The specimen is cured in a standard curing room at 20±2℃ and relative humidity above 95%. After the specimen has been cured for 28 days, it is removed and its flexural strength is measured using the three-point loading method. The loading speed of the universal testing machine is controlled at 0.5MPa / s until the specimen breaks. The result is expressed as the average value.

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

[0089]

[0090] Analysis of the data in the table above shows that, in Examples 1-3 of this invention, the mechanical properties of the concrete samples were significantly improved by modifying the fibers once with cuprammonium cellulose hydrosol, compared with Comparative Example 1, which did not modify the fibers. In Examples 4-6, silica with a particle size of 20-40 nm was generated in situ on the fiber surface. Compared with Example 3, the mechanical properties of the concrete samples were further significantly improved, especially in Example 5, where the concrete mechanical properties were the best.

[0091] Compared to Example 4, Example 7, which involves coating silica onto the fiber surface, yielded significantly less effective results than in-situ silica generation on the fiber surface. This is because, firstly, in-situ silica generation allows for a more uniform distribution on the fiber surface, reducing the aggregation of silica nanoparticles; secondly, it fills gaps in the fiber surface, resulting in a smoother surface and mitigating surface defects to some extent.

[0092] Comparing the concrete samples in Examples 2-6, it can be seen that the choice of fiber is also very important. The present invention uses coconut shell fiber, cotton stalk fiber, and polypropylene fiber, and limits the fiber length, fineness, and mass ratio, which makes a significant technical contribution to the mechanical properties of concrete and the uniformity of fibers.

[0093] 4. Carbonation test: According to the national standard GB / T50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", this test uses 100mm*100mm*400mm test blocks. During the carbonation process, test blocks are taken at 3d, 7d, 14d and 28d respectively, and the fracture depth is measured by splitting method.

[0094]

[0095] Analysis of the data in the table above shows that, in Examples 1-3 of this invention, the fiber was modified once using cuprammonium cellulose hydrosol, and the durability of the concrete samples was significantly improved compared with Comparative Example 1, which did not modify the fiber. Compared with Example 3, Examples 4-6 generated silica in situ on the fiber surface, and the durability of the concrete samples was further significantly improved. In particular, Example 5 showed the best mechanical properties of the concrete.

[0096] Comparing the concrete samples in Examples 2-6, it can be seen that the choice of fiber is also very important. The present invention uses coconut shell fiber, cotton stalk fiber, and polypropylene fiber, and limits the fiber length, fineness, and mass ratio, which makes a significant 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 90% humidity and 25℃ for curing. Cracks were observed on the concrete surface after 12 days and 24 days.

[0098] Experiment number Does crack appear in 12 days? Did cracks appear in 24 days? 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] Analysis of the data in the table above shows that, as seen in Examples 1-3, coating the fiber surface with cuprammonium cellulose effectively prevents concrete from cracking; as seen in Examples 4-6, generating nano-silica particles in situ on the fiber surface can also effectively prevent concrete from cracking; and as seen in Comparative Examples 2-6, selecting specific fibers and specific proportions, and choosing different lengths and finenesses for different fibers can effectively prevent concrete from cracking.

[0100] 6. Slump Test: Use a funnel-shaped slump cone with a top opening of 100mm, a bottom opening of 200mm, and a height of 300mm. Fill the cone with concrete in three stages. After each filling, use a tamping hammer to evenly tap the cone 25 times from the outside to the inside along the wall, compacting and smoothing the surface. Then lift the cone. The concrete will slump due to its own weight. The slump is calculated by subtracting the height of the highest point of the slumped concrete from the height of the cone. The diameter of the concrete flow area is the spread.

[0101]

[0102] Analysis of the data in the table above shows that, as seen in Examples 1-3, coating the fiber surface with cuprammonium cellulose improves the fluidity and workability of the concrete; as seen in Examples 4-6, the in-situ generation of nano-silica particles on the fiber surface further enhances the fluidity of the concrete; and as seen in Comparative Examples 2-6, the selection of specific fibers, specific proportions, and different fiber lengths and finenesses have a significant impact on the fluidity of the concrete and the workability between the multiple components.

[0103] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0104] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A type of concrete material for building construction, characterized in that, The raw materials include the following parts by weight: 400-600 parts cement, 2-5 parts water-reducing agent, 600-800 parts coarse aggregate, 300-500 parts fine aggregate, 5-10 parts fly ash, 10-80 parts silica fume, 5-15 parts composite modified fiber, and 100-150 parts water. The composite modified fiber includes modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber, with a mass ratio of 1:(0.5-1):(2-3). The preparation method of the composite modified fiber is as follows: cellulose nanofibers are dispersed in a copper ammonia solvent until the cellulose nanofibers are completely dissolved, and after aging, a nano-copper ammonia cellulose hydrosol is obtained; coconut shell fiber, cotton stalk fiber, and polypropylene fiber are immersed in the nano-copper ammonia cellulose hydrosol in batches and ultrasonically treated, and after drying, modified coconut shell fiber, modified cotton stalk fiber, and modified polypropylene fiber are obtained respectively; 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 a reaction solution and reacted at 30-60℃ for 10-50 min, and after drying, a composite modified fiber after secondary modification is obtained.

2. The concrete material for building construction according to claim 1, characterized in that, 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.

3. The concrete material for building construction according to claim 1, characterized in that, The concentration of the nano-copper ammonia cellulose hydrosol is 0.5-1.5 mol / L; the particle size of the cellulose nanocrystals is 100-150 nm.

4. A building concrete material according to claim 1, characterized in that, In a mixed solution of tetraethyl orthosilicate and ethanol, the content of tetraethyl orthosilicate is 60-80%. The reaction solution is a mixture of ethanol, water, pH adjuster and dispersant. The pH adjuster is ammonia 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.

5. A building concrete material according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate-based water-reducing agent or an aminosulfonate water-reducing agent.

6. A building concrete material according to claim 1, characterized in that, The coarse aggregate is ceramsite, crushed stone, or pebbles with a particle size of 10-20 mm.

7. A building concrete material according to claim 1, characterized in that, The fine aggregate is ceramsite sand, river sand or quartz sand, with a particle size of 0.2-2mm.

8. A building concrete material according to claim 1, characterized in that, Before being immersed in nano-copper ammonium cellulose hydrosol, coconut shell fiber, cotton stalk fiber, and polypropylene fiber undergo a fiber pretreatment step. The fiber pretreatment step includes immersing the three types of fibers in a 1-3% sodium hydroxide solution at 30-50℃ for 10-20 minutes, rinsing them with water, and then drying them.

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