Concrete prepared based on recycled fiber and preparation method thereof

Abstract

This application relates to the field of concrete and specifically discloses a concrete prepared based on recycled fiber and a preparation method thereof. The concrete comprises the following raw materials: cement, coarse aggregate, fine aggregate, water, admixture, recycled fiber, carbonized filler, and mineral admixture. The recycled fiber comprises a mixture of alkalized glass fiber scraps and modified waste textile fiber, wherein the modified waste textile fiber is prepared by sequentially treating waste fiber with oxygen plasma and then impregnating it with a modifying liquid. The preparation method comprises the following steps: mixing the cement, coarse aggregate, and fine aggregate, adding the carbonized filler and mineral admixture, stirring, and then adding the recycled fiber to prepare a powder mixture; and mixing the admixture with water, adding the powder mixture, and stirring to prepare concrete. This application has the characteristic of enabling the use of recycled waste fiber in concrete as recycled fiber to improve concrete performance.

Description

Technical Field

[0001] The present application relates to the field of concrete, and more particularly, to a concrete prepared based on recycled fibers and a preparation method thereof. Background Art

[0002] With the world's increasing attention to sustainable development and environmental protection, how to efficiently utilize renewable resources has become a research hotspot in various fields, especially in the field of building materials. Exploring the application of recycled fibers not only helps reduce waste emissions, but also significantly improves the performance of building materials. As a renewable resource, recycled fibers have broad application prospects in concrete.

[0003] A large amount of textile and clothing waste is generated every year around the world, making it one of the world's major solid wastes. Most of this waste is landfilled or incinerated, which not only takes up a lot of land resources but also releases harmful gases and causes environmental pollution. Converting the above-mentioned waste fibers into recycled fibers and applying them to concrete can effectively reduce the amount of these wastes and reduce the pressure on the environment.

[0004] Although there is currently research on applying fibers to concrete to improve the durability of concrete, traditional materials such as steel fiber and glass fiber, compared with the above traditional materials, the cost of waste fibers is lower, which can effectively reduce the cost of building materials, while solving the problem of waste and realizing the reuse of waste. Therefore, how to regenerate the above waste fibers and apply them as recycled fibers in concrete to improve the performance of concrete is of great significance. Summary of the Invention

[0005] In order to recycle waste concrete into recycled fibers and apply them to concrete to improve the performance of concrete, the present application provides a concrete prepared based on recycled fibers and a preparation method thereof.

[0006] In a first aspect, the present application provides a concrete prepared based on recycled fibers, using the following technical solution:

[0007] A concrete prepared based on recycled fiber, comprising the following raw materials in parts by weight:

[0008] 450-530 parts of cement, 760-850 parts of coarse aggregate, 500-600 parts of fine aggregate, 120-150 parts of water, 3-6 parts of admixtures, 20-30 parts of recycled fiber, 50-80 parts of carbonized filler and 60-80 parts of mineral admixtures;

[0009] The regenerated fibers include a mixture of alkalized glass fiber scraps and modified waste textile fibers in a mass ratio of 1:(0.6-0.8), wherein the modified waste textile fibers are prepared by sequentially treating waste fibers including cotton fibers and polyester fibers with oxygen plasma and then impregnating with a modifying solution, wherein the modifying solution includes tert-butyl ester, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid, and dimethylaminoethyl methacrylate;

[0010] Waste fibers are obtained by crushing textile waste, magnetically separating it, and then washing and desizing it.

[0011] By adopting the above technical solution, the recycled fiber in this application is a mixture of alkalized glass fiber scraps and modified waste textile fibers. The glass fiber scraps can significantly strengthen the concrete, and the high elongation and flexibility of the cotton fiber complement the high modulus of the polyester fiber to construct a toughness support system in the concrete, which plays a bridging role in improving the mechanical properties and crack resistance of the concrete. Moreover, after the glass fiber scraps are alkalized, the roughness of the glass fiber is improved, and on the other hand, oxygen-containing functional groups are introduced on their surface. In combination with the waste fiber being treated with oxygen plasma, the roughness of the waste fiber can be improved, and on the other hand, oxygen-containing functional groups are introduced on their surface. In this way, on the one hand, it is helpful for the glass fiber scraps to overlap with the modified waste textile fibers, so that a three-dimensional randomly distributed support structure can be formed inside the concrete, which has better reinforcement and crack resistance, and can also form a more complex mechanical bite with the cement slurry to improve the mechanical properties and crack resistance.

[0012] On the other hand, after the waste fiber is treated in the modifying liquid, the introduction of functional groups such as amino and carboxyl groups can form chemical bonds with the hydroxyl groups on the surface of the glass fiber, thereby improving the connection strength of the recycled fiber, and also improving the interfacial bonding performance between it and the cement base, so that it is evenly dispersed in the cement-based material, which can better play a bridging role and delay the initiation and expansion of cracks; and after being treated with the modifying liquid, its sulfonic acid group can chelate with cement hydration products such as calcium ions in calcium hydroxide, thereby improving the interfacial bonding strength between the recycled fiber and the cement matrix, and the dimethylamino group is protonated in the alkaline environment of concrete to form a cationic site, so that it can be adsorbed on the surface of negatively charged cement particles, reducing fiber agglomeration and improving dispersibility. The introduction of tertiary carbonate groups can not only form a steric hindrance between fibers and reduce agglomeration, but also improve the hygroscopic properties of cotton fibers due to their steric hindrance, alleviating the stress caused by fiber shrinkage when the cotton fibers absorb moisture and dry, forming crack expansion.

[0013] Finally, the addition of recycled fibers in this application is based on glass fiber scraps and waste textile fibers, which are post-processed and then added to achieve the regeneration of waste fibers and their reuse in concrete, reducing costs, solving the problem of waste disposal, and significantly improving the mechanical properties and durability of concrete.

[0014] Optionally, when preparing the modified waste textile fibers, the specific operation of the oxygen plasma treatment is: treating the waste fibers at a power of 150-200 W and an oxygen flow rate of 50-80 sccm for 3-5 minutes, and the oxygen plasma treatment is carried out at a vacuum degree of 10-20 Pa to obtain pretreated waste fibers.

[0015] By adopting the above technical solution, waste fibers containing cotton fibers and polyester fibers are first treated with oxygen plasma, thereby introducing functional groups such as hydroxyl and carboxyl groups on the surface of the waste fibers, thereby improving the defect of poor hydrophobicity of the polyester fibers and poor compatibility with cement-based concrete. The waste fibers are then modified in a modifying liquid. The carboxyl functional groups in the maleic anhydride in the modifying liquid can form chemical bonds with the hydroxyl functional groups on the waste fibers, and the unsaturated double bonds at the other ends can be copolymerized with the unsaturated double bonds in tert-butyl carbonate, 2-acrylamide-2-methylpropanesulfonic acid, and dimethylaminoethyl methacrylate. In this way, sulfonic acid groups are introduced by 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate is introduced by dimethylaminoethyl methacrylate, and tert-butyl carbonate groups are introduced by tert-butyl carbonate. The waste fibers are then added to concrete to interact with the cement base material and alkalized glass fibers to improve the performance of the concrete.

[0016] Optionally, when preparing the modified waste textile fibers, the specific operation of the modification liquid impregnation treatment is as follows: first, tert-butyl vinyl carbonate, maleic anhydride and acetone solution are mixed to prepare a primary modification liquid, then the pretreated waste fibers treated with oxygen plasma are added to the primary modification liquid, ammonium persulfate is added, the temperature is raised to 50-60° C., and the fibers are impregnated at a pressure of 0.2-0.3 MPa for 40-60 minutes, and dried to obtain the primary modified waste fibers;

[0017] Then, 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water are mixed to prepare a modified impregnation solution, and then the obtained primary modified waste fiber is added to the modified impregnation solution, and ammonium persulfate is added and the temperature is raised to 70-80°C. After impregnation treatment for 40-60 minutes, the modified waste textile fiber is dried.

[0018] By adopting the above technical solution, the pretreated waste fibers after oxygen plasma treatment are first immersed in a tert-butyl ester solution to introduce tert-butyl ester groups on the pretreated waste fibers to form a hydrophobic interface layer, and then immersed in a mixed solution of 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate for grafting modification to introduce sulfonic acid groups and dimethylamino groups to form a hydrophilic interface. In this way, a hydrophobic-hydrophilic gradient interface layer is formed on the waste fibers, which can utilize the steric hindrance effect of the tert-butyl ester groups in the hydrophobic layer to alleviate the agglomeration of the waste fibers and help dispersion, and also alleviate the hygroscopic properties of the cotton fibers. At the same time, the hydrophilic layer interface of the outer layer can enhance the mechanical bite and interfacial adhesion properties with the cement matrix, which helps to improve the mechanical properties and durability of the concrete.

[0019] Optionally, during the impregnation treatment with the modification solution, the mass ratio of versatate, maleic anhydride and acetone solution is 1:(2-3):(3-4), the mass ratio of pretreated waste fiber to primary modification solution is 1:(4-6), and the amount of ammonium persulfate added to the primary modification solution is 0.2-0.6wt% of the pretreated waste fiber;

[0020] The added mass ratio of 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water is 1:(1-1.2):(6-8), and the added mass ratio of the primary reformed waste fiber to the modified impregnation solution is 1:(4-6). The amount of ammonium persulfate added to the modified impregnation solution is 0.5-1% of the amount of the primary reformed waste fiber.

[0021] By adopting the above technical solution, the addition amount of tert-butyl ester can not only improve the moisture absorption performance of cotton fibers to a certain extent, preventing shrinkage cracks formed after subsequent drying due to water absorption, but also improve the agglomeration phenomenon between fibers and improve the performance of concrete.

[0022] Optionally, during the modification liquid impregnation treatment, when 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate are mixed with water, 4-amino-2,2-dimethylbutyric acid and N-(hydroxymethyl)acrylamide are also added, and the amount of 4-amino-2,2-dimethylbutyric acid added is 1-3wt% of the primary modified waste fiber, and the amount of N-(hydroxymethyl)acrylamide added is 0.5-1wt% of the primary modified waste fiber.

[0023] By adopting the above technical solution, the introduction of 4-amino-2,2-dimethylbutyric acid can introduce amino groups on the waste fibers, form hydrogen bonds with cement hydration products, enhance interfacial chemical adhesion, and improve mechanical properties and crack resistance. The addition of N-(hydroxymethyl)acrylamide forms a three-dimensional network structure through a cross-linking reaction, thereby further improving the mechanical properties and crack resistance, improving the mechanical properties of textile waste fibers, and improving the performance of concrete.

[0024] Optionally, the alkalized glass fiber scraps are prepared by the following method:

[0025] The glass fiber scraps are immersed in a sodium hydroxide solution with a mass concentration of 10-15% for 5-10 minutes, filtered and dried to obtain the alkalized glass fiber scraps.

[0026] Optionally, the carbonized filler is prepared by the following method:

[0027] The waste fiber is mixed with iron-containing sludge, starch and polyvinyl alcohol in a mass ratio of 1: (0.1-0.2): (0.2-0.3): (0.05-0.1), and water is added to stir into a slurry with a water content of 5-10%. The slurry is first treated at 350-380°C for 40-60 minutes, and then heated to 650-700°C and treated for 40-60 minutes to obtain a carbonized filler.

[0028] By adopting the above-mentioned technical solution, in this application, waste fibers and iron-containing sludge are subjected to pyrolysis treatment. The iron element in the iron-containing sludge acts as a catalyst to promote the fiber decomposition to form an amorphous carbon precursor, and then the temperature is continued to rise to form a carbon skeleton filler. The addition of polyvinyl alcohol helps to bond and mix the waste fibers, iron-containing sludge and starch. The addition of starch serves as a carbon skeleton source and pore-forming agent, so that the prepared carbonized filler has a certain microporous structure. Its tiny pore structure can relieve the stress concentration inside the concrete, and its pore structure can store a certain amount of environmental moisture, which is released when drying to maintain the humidity inside the concrete, achieving a certain degree of self-curing and improving the durability of the concrete.

[0029] Optionally, the mineral admixture is nano-silicon dioxide and metakaolin in a mass ratio of 1:(2-3).

[0030] By adopting the above technical solution, nano-silica and metakaolin are selected as mineral admixtures, and their volcanic ash effect forms a three-dimensional gel network with the carbon nanostructure in the carbonized filler, thereby improving the density of the concrete matrix and enhancing the mechanical properties.

[0031] Optionally, the coarse aggregate is crushed stone with a continuous grade particle size of 5-15 mm, the fine aggregate is machine-made sand with a fineness modulus of 2.5-3; and the admixture is polycarboxylate water reducer.

[0032] In a second aspect, the present application provides a method for preparing concrete based on recycled fibers, which adopts the following technical solution:

[0033] A method for preparing concrete based on recycled fiber comprises the following steps:

[0034] After mixing cement, coarse aggregate and fine aggregate, carbonized filler and mineral admixture are added, and after stirring, recycled fiber is added to prepare a powder mixture;

[0035] The admixture is mixed with water and then added to the powder mixture and stirred to prepare concrete.

[0036] By adopting the above technical solution, the method provided by the present application is simple, convenient, easy to industrialize, and realizes waste recycling.

[0037] In summary, this application has the following beneficial effects:

[0038] 1. The recycled fiber in this application is a mixture of alkalized glass fiber scraps and modified waste textile fibers. The glass fiber scraps can significantly strengthen the concrete, while the high elongation and flexibility of the cotton fiber complement the high modulus of the polyester fiber to form a tough support system in the concrete, play a bridging role, and improve the mechanical properties and crack resistance of the concrete.

[0039] 2. In the present application, after the waste fibers are treated in the modifying liquid, the functional groups such as amino and carboxyl groups introduced therein can form chemical bonds with the hydroxyl groups on the surface of the glass fibers, thereby improving the connection strength of the regenerated fibers, and also improving the interfacial bonding performance between the waste fibers and the cement base, so that the waste fibers are evenly dispersed in the cement-based materials, which can better play a bridging role and delay the initiation and expansion of cracks. Moreover, after being treated with the modifying liquid, the sulfonic acid groups thereof can chelate with the cement hydration products such as calcium ions in calcium hydroxide to improve the interfacial bonding strength between the regenerated fibers and the cement matrix, and the dimethylamino groups are protonated in the alkaline environment of the concrete to form cationic sites, which can be adsorbed on the surface of the negatively charged cement particles, reduce fiber agglomeration, and improve dispersibility. The introduction of tertiary carbonate groups can not only form a steric hindrance between the fibers and reduce agglomeration, but also improve the hygroscopic properties of the cotton fibers due to their steric hindrance, thereby alleviating the stress caused by fiber shrinkage when the cotton fibers absorb moisture and dry, thereby forming crack expansion. DETAILED DESCRIPTION

[0040] The present application is further described in detail below with reference to the examples. It is particularly noted that if no specific conditions are specified in the following examples, the reactions are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0041] In the following examples, PO 42.5 ordinary Portland cement was used as cement;

[0042] The polycarboxylate water reducer is PCA®-9 series polycarboxylate high efficiency water reducer produced by Jiangsu Subote New Materials Co., Ltd.

[0043] The waste fibers in the following preparation examples and embodiments were prepared by crushing waste clothing and fabrics into 5-10 mm pieces using a fiber opener, followed by magnetic separation to remove metal impurities. The waste fibers were then soaked in 5 wt % sodium hydroxide at 50° C. for 20 min, followed by soaking in a 5% OP-10 surfactant solution at 40° C. for 15 min, followed by washing with water to remove residual chemicals, oil stains, color, etc., and then dehydrated and dried to obtain the waste fibers.

[0044] The raw waste fibers used to prepare the modified waste textile fibers in the following preparation examples and the waste fibers used to prepare the carbonized fillers in the examples are all waste fibers prepared by the above method.

[0045] The following preparation examples are examples of the preparation of modified waste textile fibers:

[0046] Preparation Example 1

[0047] A method for preparing modified waste textile fibers comprises the following steps:

[0048] 1) Waste fibers containing cotton fibers and polyester fibers were treated at a power of 180 W and an oxygen flow rate of 60 sccm for 4 minutes, and the oxygen plasma treatment was performed at a vacuum degree of 15 Pa to obtain pretreated waste fibers;

[0049] 2) The tert-butyl vinyl carbonate, maleic anhydride and 65wt% acetone aqueous solution were mixed in an addition mass ratio of 1:2:3 to prepare a primary reforming liquid, and then the pretreated waste fiber treated with oxygen plasma was added to the primary reforming liquid, and the addition mass ratio of the pretreated waste fiber to the primary reforming liquid was 1:5. Ammonium persulfate was added, and the amount of ammonium persulfate added to the primary reforming liquid was 0.4wt% of the pretreated waste fiber. The temperature was raised to 55°C, and the mixture was immersed under a pressure of 0.2MPa for 50min. After drying, the primary reformed waste fiber was obtained;

[0050] Then, 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water are mixed in a mass ratio of 1:1.1:7 to prepare a modified impregnation solution, and then the obtained primary modified waste fiber is added to the modified impregnation solution, and the addition mass ratio of the primary modified waste fiber to the modified impregnation solution added with 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate is 1:5. Ammonium persulfate is added, and the amount of ammonium persulfate added to the modified impregnation solution is 0.8wt% of the amount of the primary modified waste fiber. Then, the temperature is raised to 75°C, and after impregnation treatment for 50 minutes under a pressure of 0.2MPa, it is dried to obtain the modified waste textile fiber.

[0051] Preparation Example 2

[0052] A method for preparing modified waste textile fibers comprises the following steps:

[0053] 1) treating waste fibers containing cotton fibers and polyester fibers at a power of 150 W and an oxygen flow rate of 50 sccm for 5 minutes, and performing the oxygen plasma treatment at a vacuum degree of 10 Pa to obtain pretreated waste fibers;

[0054] 2) The tert-butyl vinyl carbonate, maleic anhydride and 65wt% acetone aqueous solution were mixed in an addition mass ratio of 1:2:3 to prepare a primary reforming liquid, and then the pretreated waste fiber treated with oxygen plasma was added to the primary reforming liquid, and the addition mass ratio of the pretreated waste fiber to the primary reforming liquid was 1:4. Ammonium persulfate was added, and the amount of ammonium persulfate added to the primary reforming liquid was 0.2wt% of the pretreated waste fiber. The temperature was raised to 50°C, and the mixture was immersed under a pressure of 0.2MPa for 60min. After drying, the primary reformed waste fiber was obtained;

[0055] Then, 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water are mixed in a mass ratio of 1:1:6 to prepare a modified impregnation solution, and then the obtained primary modified waste fiber is added to the modified impregnation solution, and the addition mass ratio of the primary modified waste fiber to the modified impregnation solution added with 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate is 1:4. Ammonium persulfate is added, and the amount of ammonium persulfate added to the modified impregnation solution is 0.5wt% of the amount of the primary modified waste fiber. Then, the temperature is raised to 70°C, and after impregnation treatment for 60 minutes under a pressure of 0.2MPa, it is dried to obtain the modified waste textile fiber.

[0056] Preparation Example 3

[0057] A method for preparing modified waste textile fibers comprises the following steps:

[0058] 1) treating waste fibers containing cotton fibers and polyester fibers at a power of 200 W and an oxygen flow rate of 80 sccm for 3 minutes, and performing the oxygen plasma treatment at a vacuum degree of 20 Pa to obtain pretreated waste fibers;

[0059] 2) A primary reforming solution was prepared by mixing versatate, maleic anhydride and a 65wt% acetone aqueous solution in a mass ratio of 1:3:4, and then the pretreated waste fiber treated with oxygen plasma was added to the primary reforming solution, and the addition mass ratio of the pretreated waste fiber to the primary reforming solution was 1:6. Ammonium persulfate was added, and the amount of ammonium persulfate added to the primary reforming solution was 0.6wt% of the pretreated waste fiber. The temperature was raised to 60°C, and the mixture was immersed under a pressure of 0.3MPa for 40 minutes. After drying, the primary reformed waste fiber was obtained;

[0060] Then, 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water are mixed in a mass ratio of 1:1.2:8 to prepare a modified impregnation solution, and then the obtained primary modified waste fiber is added to the modified impregnation solution, and the addition mass ratio of the primary modified waste fiber to the modified impregnation solution added with 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate is 1:6. Ammonium persulfate is added, and the amount of ammonium persulfate added to the modified impregnation solution is 1wt% of the amount of the primary modified waste fiber. Then, the temperature is raised to 80°C, and after impregnation treatment for 40 minutes under a pressure of 0.3MPa, it is dried to obtain the modified waste textile fiber.

[0061] Preparation Example 4

[0062] A method for preparing modified waste textile fibers is carried out according to the method in Preparation Example 1, except that 4-amino-2,2-dimethylbutyric acid and N-(hydroxymethyl)acrylamide are further added to the modified impregnation solution in step 2), and the amount of 4-amino-2,2-dimethylbutyric acid added is 2wt% of the initially modified waste fibers, and the amount of N-(hydroxymethyl)acrylamide added is 0.8wt% of the initially modified waste fibers.

[0063] Preparation Example 5

[0064] A method for preparing modified waste textile fibers is carried out according to the method in Preparation Example 1, except that 4-amino-2,2-dimethylbutyric acid and N-(hydroxymethyl)acrylamide are further added to the modified impregnation solution in step 2), and the amount of 4-amino-2,2-dimethylbutyric acid added is 1wt% of the initially modified waste fiber, and the amount of N-(hydroxymethyl)acrylamide added is 0.5wt% of the initially modified waste fiber.

[0065] Preparation Example 6

[0066] A method for preparing modified waste textile fibers is carried out according to the method in Preparation Example 1, except that, in step 2), 4-amino-2,2-dimethylbutyric acid and N-(hydroxymethyl)acrylamide are further added to the modified impregnation solution, and the amount of 4-amino-2,2-dimethylbutyric acid added is 3wt% of the initial modified waste fiber, and the amount of N-(hydroxymethyl)acrylamide added is 1wt% of the initial modified waste fiber.

[0067] Comparative Preparation Example 1

[0068] A method for preparing modified waste textile fibers is carried out according to the method in Preparation Example 1, except that versatate is not added in step 2).

[0069] Comparative Preparation Example 2

[0070] A method for preparing modified waste textile fibers is carried out according to the method in Preparation Example 1, except that 2-acrylamide-2-methylpropanesulfonic acid is not added in step 2).

[0071] Comparative Preparation Example 3

[0072] A method for preparing modified waste textile fibers is carried out according to the method in Preparation Example 1, except that an equal amount of dimethylaminoethyl methacrylate is replaced by KH-550.

[0073] Comparative Preparation Example 4

[0074] A method for preparing modified waste textile fibers is carried out according to the method in Preparation Example 1, without performing step 2).

[0075] The following preparation example is an example of preparing alkalized glass fiber scraps:

[0076] Preparation Example 7

[0077] A method for preparing alkalized glass fiber scraps comprises the following steps:

[0078] The fiber scraps produced during the preparation of glass fiber were immersed in a sodium hydroxide solution with a mass concentration of 12% for 10 minutes, and then filtered and dried to obtain alkalized glass fiber scraps.

[0079] Preparation Example 8

[0080] A method for preparing alkalized glass fiber scraps comprises the following steps:

[0081] The fiber scraps produced during the glass fiber preparation process were immersed in a sodium hydroxide solution with a mass concentration of 10% for 10 minutes, and then filtered and dried to obtain the alkalized glass fiber scraps.

[0082] Preparation Example 9

[0083] A method for preparing alkalized glass fiber scraps comprises the following steps:

[0084] The fiber scraps produced during the preparation of glass fiber were immersed in a sodium hydroxide solution with a mass concentration of 15% for 5 minutes, and then filtered and dried to obtain alkalized glass fiber scraps.

[0085] Example 1

[0086] A method for preparing concrete based on recycled fiber comprises the following steps:

[0087] 480 kg of cement, 800 kg of coarse aggregate, and 550 kg of fine aggregate were mixed, 60 kg of carbonized filler and 70 kg of mineral admixture were added, and after stirring, 25 kg of recycled fiber was added to prepare a powder mixture;

[0088] 4 kg of admixture was mixed with 135 kg of water and then added to the powder mixture and stirred to prepare concrete.

[0089] The coarse aggregate is crushed stone with a continuous particle size of 5-15mm, the fine aggregate is machine-made sand with a fineness modulus of 2.5-3; the admixture is polycarboxylate water reducer;

[0090] Mineral admixtures are nano-silica and metakaolin with a mass ratio of 1:2.5;

[0091] The regenerated fiber is a mixture of alkalized glass fiber scraps and modified waste textile fibers in a mass ratio of 1:0.7, the alkalized glass fiber scraps are the alkalized glass fiber scraps prepared in Preparation Example 7, and the modified waste textile fibers are the modified waste textile fibers prepared in Preparation Example 1;

[0092] Carbonized fillers are prepared by the following method:

[0093] Waste fiber, iron-containing sludge (iron-containing sludge with an iron content of 5wt% formed after water treatment and the addition of coagulants such as polyferric sulfate), starch and polyvinyl alcohol are mixed in a mass ratio of 1:0.15:0.25:0.08, and water is added to stir into a slurry with a water content of 8%. The slurry is then first treated at 370°C for 50 minutes, and then heated to 680°C and treated for 50 minutes to obtain a carbonized filler.

[0094] Example 2

[0095] A method for preparing concrete based on recycled fiber comprises the following steps:

[0096] 450 kg of cement, 760 kg of coarse aggregate, and 500 kg of fine aggregate were mixed, 50 kg of carbonized filler and 60 kg of mineral admixture were added, and after stirring, 20 kg of recycled fiber was added to prepare a powder mixture;

[0097] 3 kg of admixture was mixed with 120 kg of water, added to the powder mixture, and stirred to prepare concrete.

[0098] The coarse aggregate is crushed stone with a continuous particle size of 5-15mm, the fine aggregate is machine-made sand with a fineness modulus of 2.5-3; the admixture is polycarboxylate water reducer;

[0099] The mineral admixtures are nano-silica and metakaolin with a mass ratio of 1:2;

[0100] The regenerated fiber is a mixture of alkalized glass fiber scraps and modified waste textile fibers in a mass ratio of 1:0.6, the alkalized glass fiber scraps are the alkalized glass fiber scraps prepared in Preparation Example 8, and the modified waste textile fibers are the modified waste textile fibers prepared in Preparation Example 2;

[0101] Carbonized fillers are prepared by the following method:

[0102] Waste fiber, iron-containing sludge (iron-containing sludge with an iron content of 5wt% formed after water treatment and the addition of coagulants such as polyferric sulfate), starch and polyvinyl alcohol are mixed in a mass ratio of 1:0.1:0.2:0.05, and water is added to stir into a slurry with a water content of 5%. The slurry is then first treated at 350°C for 60 minutes, and then heated to 650°C and treated for 60 minutes to obtain a carbonized filler.

[0103] Example 3

[0104] A method for preparing concrete based on recycled fiber comprises the following steps:

[0105] 530 kg of cement, 850 kg of coarse aggregate, and 600 kg of fine aggregate were mixed, and 80 kg of carbonized filler and 80 kg of mineral admixture were added. After stirring, 30 kg of recycled fiber was added to prepare a powder mixture.

[0106] 6 kg of admixture was mixed with 150 kg of water and then added to the powder mixture and stirred to prepare concrete.

[0107] The coarse aggregate is crushed stone with a continuous particle size of 5-15mm, the fine aggregate is machine-made sand with a fineness modulus of 2.5-3; the admixture is polycarboxylate water reducer;

[0108] The mineral admixtures are nano-silica and metakaolin with a mass ratio of 1:3;

[0109] The regenerated fiber is a mixture of alkalized glass fiber scraps and modified waste textile fibers in a mass ratio of 1:0.8, the alkalized glass fiber scraps are the alkalized glass fiber scraps prepared in Preparation Example 9, and the modified waste textile fibers are the modified waste textile fibers prepared in Preparation Example 3;

[0110] Carbonized fillers are prepared by the following method:

[0111] Waste fiber, iron-containing sludge (iron-containing sludge with an iron content of 5wt% formed after water treatment and the addition of coagulants such as polyferric sulfate), starch and polyvinyl alcohol are mixed in a mass ratio of 1:0.2:0.3:0.1, and water is added to stir into a slurry with a water content of 10%. The slurry is then first treated at 380°C for 40 minutes, and then heated to 700°C and treated for 40 minutes to obtain a carbonized filler.

[0112] Examples 4-6

[0113] A method for preparing concrete based on recycled fibers is carried out according to the method in Example 1, except that the modified waste textile fibers are the modified waste textile fibers prepared in Preparation Examples 4-6, respectively.

[0114] Example 7

[0115] A method for preparing concrete based on recycled fiber is carried out according to the method in Example 1, except that starch is not added in the step of preparing the carbonized filler.

[0116] Comparative Example 1

[0117] A method for preparing concrete based on recycled fiber is carried out according to the method in Example 1, except that alkalized glass fiber scraps are used as the recycled fiber.

[0118] Comparative Examples 2-5

[0119] A method for preparing concrete based on recycled fibers is carried out according to the method in Example 1, except that the modified waste textile fibers are the modified waste textile fibers prepared in Comparative Preparation Examples 1-4, respectively.

[0120] Comparative Example 6

[0121] A method for preparing concrete based on recycled fibers is carried out according to the method in Example 1, except that no carbonized filler is added to the raw materials.

[0122] Comparative Example 7

[0123] A method for preparing concrete based on recycled fibers is carried out according to the method in Example 1, except that an equal amount of modified waste textile fibers in the recycled fibers are replaced by unmodified waste textile fibers.

[0124] Performance testing

[0125] The concrete prepared in the examples and comparative examples of the present application was tested for 28d compressive strength and crack resistance. The compressive strength was tested with reference to GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", and the crack resistance was tested with reference to GB / T 50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete". The number and total length of cracks were counted, and the statistical results are shown in Table 1 below.

[0126] Table 1:

[0127]

[0128] Referring to the test results in Table 1 above, the embodiment of the present application uses the regenerated fiber and the carbonized filler to work together, significantly improving the compressive strength of the concrete while reducing the number and total length of cracks, and having excellent mechanical properties and Kanglei performance. This is because the regenerated fiber forms a three-dimensional randomly distributed support structure inside the concrete, enhancing the integrity and toughness of the concrete material. At the same time, the addition of the carbonized filler forms a certain stress buffer system, improving the mechanical properties and crack resistance of the concrete; combined with the test results of Example 1 and Examples 4-6, 4-amino-2,2-dimethylbutyric acid and N-(hydroxy When starch is added to the carbonized filler, it helps to introduce functional groups such as amino groups into the waste fibers, change the fiber activity, promote the chemical bonding between the fibers and the cement matrix, and between the waste fibers and the glass fiber scraps, and further improve the mechanical properties and durability of the concrete. Combined with the test results of Example 7, when starch is not added to the carbonized filler, its compressive strength and crack resistance are slightly reduced. The addition of starch can serve as a source of carbon skeleton and as a pore-forming agent to form a certain pore structure, provide stress buffering, and ultimately improve the crack resistance while compensating for the strength loss caused by the pores.

[0129] Referring to the test results of Example 1 and Comparative Example 1, when only alkalized glass fiber scraps were used as the regenerated fiber, the compressive strength and crack resistance were significantly reduced. Combined with the test results of Comparative Examples 2-4, when no tert-butyl ester was added to the modified impregnation liquid, the crack resistance and strength were reduced. When no 2-acrylamide-2-methylpropanesulfonic acid or dimethylaminoethyl methacrylate was added in Comparative Examples 3-4, the comprehensive performance was also reduced. Combined with the test results in Comparative Example 5, when the waste fiber was only treated with oxygen plasma but not modified by impregnation with the modifying liquid, its performance was significantly reduced. Combined with the test results of Comparative Examples 6 and 7, when no carbonized filler was added, its mechanical properties were reduced and the crack resistance was slightly reduced. When only waste textile fibers were added in Comparative Example 7, its performance was also significantly reduced.

[0130] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A concrete prepared based on recycled fiber, characterized in that: It includes the following raw materials in parts by weight: 450-530 parts of cement, 760-850 parts of coarse aggregate, 500-600 parts of fine aggregate, 120-150 parts of water, 3-6 parts of admixtures, 20-30 parts of recycled fiber, 50-80 parts of carbonized filler and 60-80 parts of mineral admixtures; The regenerated fibers include a mixture of alkalized glass fiber scraps and modified waste textile fibers in a mass ratio of 1:(0.6-0.8), wherein the modified waste textile fibers are prepared by sequentially treating waste fibers including cotton fibers and polyester fibers with oxygen plasma and then impregnating with a modifying solution, wherein the modifying solution includes tert-butyl ester, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid, and dimethylaminoethyl methacrylate; Waste fiber is obtained by crushing textile waste, magnetically separating it, and then washing and desizing it; Carbonized fillers are prepared by the following method: The waste fiber is mixed with iron-containing sludge, starch and polyvinyl alcohol in a mass ratio of 1: (0.1-0.2): (0.2-0.3): (0.05-0.1), and water is added to stir into a slurry with a water content of 5-10%. The slurry is first treated at 350-380°C for 40-60 minutes, and then heated to 650-700°C and treated for 40-60 minutes to obtain a carbonized filler.

2. The concrete prepared based on recycled fiber according to claim 1, characterized in that: When preparing the modified waste textile fibers, the specific operation of the oxygen plasma treatment is: treating the waste fibers for 3-5 minutes under the conditions of a power of 150-200W and an oxygen flow rate of 50-80sccm, and the oxygen plasma treatment is carried out under a vacuum degree of 10-20Pa to obtain pretreated waste fibers.

3. The concrete prepared based on recycled fiber according to claim 1, characterized in that: When preparing the modified waste textile fibers, the specific operation of the modification liquid impregnation treatment is as follows: first, versatate vinyl carbonate, maleic anhydride and acetone solution are mixed to prepare a primary modification liquid, then the pretreated waste fibers treated with oxygen plasma are added to the primary modification liquid, ammonium persulfate is added, the temperature is raised to 50-60° C., and the fibers are impregnated at a pressure of 0.2 or 0.3 MPa for 40-60 minutes, and dried to obtain the primary modified waste fibers; Then, 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water are mixed to prepare a modification liquid, and then the obtained primary modified waste fiber is added to the modification liquid, ammonium persulfate is added, and then the temperature is raised to 70-80°C, and after impregnation treatment at a pressure of 0.2 or 0.3 MPa for 40-60 minutes, it is dried to obtain the modified waste textile fiber.

4. The concrete prepared based on recycled fiber according to claim 3, characterized in that: During the modification liquid impregnation treatment, the mass ratio of versatate, maleic anhydride and acetone solution is 1:(2-3):(3-4), the mass ratio of pretreated waste fiber to primary modification liquid is 1:(4-6), and the amount of ammonium persulfate added to the primary modification liquid is 0.2-0.6wt% of the pretreated waste fiber; The added mass ratio of 2-acrylamide-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water is 1:(1-1.2):(6-8), and the added mass ratio of the primary reformed waste fiber to the modified liquid is 1:(4-6). The amount of ammonium persulfate added to the modified liquid is 0.5-1wt% of the amount of the primary reformed waste fiber.

5. The concrete prepared based on recycled fiber according to claim 3, characterized in that: During the modification liquid impregnation treatment, when 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate are mixed with water, 4-amino-2,2-dimethylbutyric acid and N-(hydroxymethyl)acrylamide are also added, and the amount of 4-amino-2,2-dimethylbutyric acid added is 1-3wt% of the primary modified waste fiber, and the amount of N-(hydroxymethyl)acrylamide added is 0.5-1wt% of the primary modified waste fiber.

6. The concrete prepared based on recycled fiber according to claim 1, characterized in that: Alkali-treated glass fiber scraps are prepared by the following method: The glass fiber scraps are immersed in a sodium hydroxide solution with a mass concentration of 10-15% for 5-10 minutes, filtered and dried to obtain the alkalized glass fiber scraps.

7. The concrete prepared based on recycled fiber according to claim 1, characterized in that: The mineral admixture is nano-silicon dioxide and metakaolin in a mass ratio of 1:(2-3).

8. The concrete prepared based on recycled fiber according to claim 1, characterized in that: The coarse aggregate is crushed stone with a continuous grade of particle size of 5-15 mm, the fine aggregate is machine-made sand with a fineness modulus of 2.5-3; and the admixture is polycarboxylate water reducer.

9. A method for preparing concrete based on recycled fibers according to any one of claims 1 to 8, characterized in that: The following steps are involved: After mixing cement, coarse aggregate and fine aggregate, carbonized filler and mineral admixture are added, and after stirring, recycled fiber is added to prepare a powder mixture; The admixture is mixed with water and then added to the powder mixture and stirred to prepare concrete.

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