Concrete prepared based on regenerated fibers and preparation method thereof

Abstract

The invention relates to the field of concrete, and particularly discloses concrete prepared based on regenerated fibers and a preparation method thereof, the concrete comprises the following raw materials: cement, coarse aggregate, fine aggregate, water, an additive, regenerated fibers, a carbonized filler and a mineral admixture; wherein the regenerated fibers comprise a mixture of alkalized glass fiber leftover materials and modified waste textile fibers, and the modified waste textile fibers are prepared by sequentially carrying out oxygen plasma treatment and modification liquid dipping treatment on waste fibers; the preparation method comprises the following steps: mixing the cement, the coarse aggregate and the fine aggregate, adding the carbonized filler and the mineral admixture, stirring, and adding the regenerated fiber to prepare a powder mixture; and mixing the admixture with water, adding the powder mixture, and stirring to obtain the concrete. The method has the characteristic that the regenerated waste fibers are used as regenerated fibers to be applied to the concrete so as to improve the performance of the concrete.

Description

Technical Field

[0001] This application relates to the field of concrete, and more specifically, it relates to a kind of concrete prepared based on recycled fibers and its preparation method. Background Art

[0002] With the global emphasis on sustainable development and environmental protection, how to efficiently utilize recycled 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 to reduce waste emissions but also can significantly improve the performance of building materials. As a renewable resource, the application of recycled fibers in concrete has broad application prospects.

[0003] A large amount of textile and clothing waste is generated globally every year, which is one of the major solid wastes in the world. Most of these wastes are landfilled or incinerated, not only occupying a large amount of land resources but also releasing harmful gases, causing environmental pollution. Converting the above-mentioned waste fibers into recycled fibers and applying them to concrete can effectively reduce the quantity of these wastes and relieve the environmental pressure.

[0004] Although there are currently studies on applying fibers to concrete to improve its durability, traditional materials such as steel fibers and glass fibers are used. Compared with the above traditional materials, waste fibers have a lower cost, can effectively reduce the cost of building materials, and at the same time solve waste problems and achieve the reuse of waste. Therefore, it is of great significance to regenerate the above waste fibers and apply them as recycled fibers to concrete to improve the performance of concrete. Summary of the Invention

[0005] In order to realize the application of recycled waste fibers as recycled fibers in concrete to improve the performance of concrete, this application provides a kind of concrete prepared based on recycled fibers and its preparation method.

[0006] In the first aspect, this application provides a kind of concrete prepared based on recycled fibers, adopting the following technical scheme: A kind of concrete prepared based on recycled fibers, comprising 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 admixture, 20 - 30 parts of recycled fiber, 50 - 80 parts of carbonization filler, and 60 - 80 parts of mineral admixture; Among them, the regenerated fiber includes a mixture of alkalized glass fiber scraps and modified waste textile fibers with a mass ratio of 1:(0.6 - 0.8). The modified waste textile fibers are prepared by successively subjecting waste fibers containing cotton fibers and polyester fibers to oxygen plasma treatment and modified liquid impregnation treatment. The modified liquid contains vinyl versatate, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid, and dimethylaminoethyl methacrylate; The waste fibers are obtained by crushing textile waste, followed by magnetic separation, and then washing and desizing.

[0007] By adopting the above technical solution, in this application, the regenerated fiber selects a mixture of alkalized glass fiber scraps and modified waste textile fibers. The glass fiber scraps can significantly enhance the concrete. The high extensibility and flexibility of cotton fibers complement the high modulus of polyester fibers to form a tough support system in the concrete, playing a bridging role to improve the mechanical properties and crack resistance of the concrete. Moreover, after the alkalization treatment of the glass fiber scraps, on the one hand, the roughness of the glass fiber is increased, and on the other hand, oxygen-containing functional groups are introduced on its surface. Combined with the oxygen plasma treatment of the waste fibers, on the one hand, the roughness of the waste fibers can also be increased, and on the other hand, oxygen-containing functional groups are introduced on its surface. In this way, on the one hand, it helps the alkalized glass fiber scraps to cooperate with the modified waste textile fibers for better lap joint, so as to form a three-dimensional random distribution support structure inside the concrete, achieving better strengthening and crack resistance, and also forming a more complex mechanical interlock with the cement paste to improve the mechanical properties and crack resistance; On the other hand, after the waste fibers are treated in the modified liquid, the introduced functional groups such as amino and carboxyl groups can form chemical bonding with the hydroxyl groups on the glass fiber surface, thereby improving the connection strength of the regenerated fiber. Moreover, it can also improve the interfacial bonding performance between the regenerated fiber and the cement matrix, enabling it to be evenly dispersed in the cement-based material, better playing the bridging role, delaying the initiation and propagation of cracks; and after being treated with the modified liquid, its sulfonic acid group can chelate with calcium ions in cement hydration products such as calcium hydroxide to improve the interfacial bonding strength between the regenerated fiber and the cement matrix. The dimethylamino group is protonated to form cationic sites in the alkaline environment of the concrete, so it can adsorb on the surface of negatively charged cement particles, reducing fiber agglomeration and improving dispersibility. The introduction of the versatic acid group can not only form a steric hindrance effect between the fibers to reduce agglomeration, but also improve the moisture absorption performance of cotton fibers due to its steric hindrance effect, alleviating the stress caused by fiber shrinkage during the moisture absorption and drying of cotton fibers and preventing crack propagation.

[0008] Finally, in this application, the addition of the regenerated fiber is based on alkalized glass fiber scraps and waste textile fibers, and it is added after post-treatment, realizing the regeneration of waste fibers and their reuse in concrete, reducing costs, solving the problem of waste treatment, and significantly improving the mechanical properties and durability of concrete.

[0009] Optionally, when preparing the modified waste textile fibers, the specific operation of the oxygen plasma treatment is as follows: treating the waste fibers at a power of 150 - 200 W and an oxygen flow rate of 50 - 80 sccm for 3 - 5 min, and the oxygen plasma treatment is carried out under a vacuum degree of 10 - 20 Pa to obtain pretreated waste fibers.

[0010] By adopting the above technical solution, the waste fibers containing cotton fibers and polyester fibers are first treated with oxygen plasma, so that functional groups such as hydroxyl groups and carboxyl groups can be introduced on the surface of the waste fibers, improving the defect that the hydrophobicity of polyester fibers and the compatibility with cement-based concrete are poor. Then, they are modified in the modification liquid. The carboxyl functional group in maleic anhydride in the modification liquid can form a chemical bond with the hydroxyl functional group on the waste fibers, and the unsaturated double bond at the other end can copolymerize with the unsaturated double bonds in vinyl versatate, 2 - acrylamido - 2 - methylpropanesulfonic acid, and dimethylaminoethyl methacrylate. In this way, the role of 2 - acrylamido - 2 - methylpropanesulfonic acid is to introduce sulfonic acid groups, the role of dimethylaminoethyl methacrylate is to introduce dimethylamino groups, and the role of vinyl versatate is to introduce tertiary carbonate groups. Then, they are added to the concrete to act with the cement base material and alkali-resistant glass fibers to improve the concrete performance.

[0011] Optionally, when preparing the modified waste textile fibers, the specific operation of the modification liquid impregnation treatment is as follows: First, vinyl versatate, maleic anhydride, and acetone solution are mixed to obtain a primary modification liquid. Then, the pretreated waste fibers after oxygen plasma treatment are added to the primary modification liquid, ammonium persulfate is added, and the temperature is raised to 50 - 60 °C, and the impregnation treatment is carried out under a pressure of 0.2 - 0.3 MPa for 40 - 60 min, and then dried to obtain primary modified waste fibers; Then, 2 - acrylamido - 2 - methylpropanesulfonic acid, dimethylaminoethyl methacrylate, and water are mixed to obtain a modified impregnation liquid. Then, the obtained primary modified waste fibers are added to the modified impregnation liquid, ammonium persulfate is added, the temperature is raised to 70 - 80 °C, and after impregnation treatment for 40 - 60 min, they are dried to obtain modified waste textile fibers.

[0012] By adopting the above technical solutions, the pretreated waste fibers after oxygen plasma treatment are first impregnated in a vinyl versatate solution to introduce vinyl versatate groups onto the pretreated waste fibers, forming a hydrophobic interface layer. Then, they are impregnated and graft-modified in a mixed solution of 2-acrylamido-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate to introduce sulfonic acid groups and dimethylamino groups, forming a hydrophilic interface. In this way, a hydrophobic-hydrophilic gradient interface layer is formed on the waste fibers. The steric hindrance effect of the vinyl versatate groups in the hydrophobic layer can alleviate the agglomeration of the waste fibers, contributing to dispersion, and also alleviate the moisture absorption performance of the cotton fibers. At the same time, the hydrophilic layer interface on the outer layer can enhance the mechanical interlocking and interfacial adhesion performance with the cement matrix, helping to improve the mechanical properties and durability of the concrete.

[0013] Optionally, when the modified liquid is impregnated and treated, the mass ratio of vinyl versatate, maleic anhydride, and acetone solution added is 1:(2 - 3):(3 - 4), the mass ratio of the pretreated waste fibers to the initially modified liquid added is 1:(4 - 6), and the addition amount of ammonium persulfate added to the initially modified liquid is 0.2 - 0.6 wt% of the pretreated waste fibers. The mass ratio of 2-acrylamido-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate, and water added is 1:(1 - 1.2):(6 - 8), the mass ratio of the initially modified waste fibers to the modified impregnating liquid added is 1:(4 - 6), and the addition amount of ammonium persulfate added to the modified impregnating liquid is 0.5 - 1% of the addition amount of the initially modified waste fibers.

[0014] By adopting the above technical solutions, the addition amount of vinyl versatate can, to a certain extent, improve the moisture absorption performance of the cotton fibers, prevent shrinkage cracks formed after subsequent drying due to water absorption, and on the other hand, can also improve the agglomeration phenomenon between the fibers and improve the concrete performance.

[0015] Optionally, when the modified liquid is impregnated and treated, when 2-acrylamido-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate are mixed with water, 4-amino-2,2-dimethylbutyric acid and N-(hydroxymethyl)acrylamide are also added. The addition amount of 4-amino-2,2-dimethylbutyric acid is 1 - 3 wt% of the initially modified waste fibers, and the addition amount of N-(hydroxymethyl)acrylamide is 0.5 - 1 wt% of the initially modified waste fibers.

[0016] By adopting the above technical solutions, the introduction of 4-amino-2,2-dimethylbutyric acid can introduce amino groups onto the waste fibers, which can form hydrogen bonds with the cement hydration products, enhance the interfacial chemical adhesion, improve the mechanical properties and crack resistance. The addition of N-(hydroxymethyl)acrylamide forms a three-dimensional network structure through cross-linking reactions, thereby further improving the mechanical properties and crack resistance, improving the mechanical properties of the waste fibers of textile materials, and improving the concrete performance.

[0017] Optionally, the alkalized glass fiber scraps are obtained by the following method: The glass fiber scraps are impregnated in a sodium hydroxide solution with a mass concentration of 10-15% for 5-10 minutes, and then filtered and dried to obtain the alkalized glass fiber scraps.

[0018] Optionally, the carbonized filler is obtained by the following method: The waste fibers, iron-containing sludge, starch, and polyvinyl alcohol are mixed in a mass ratio of 1:(0.1-0.2):(0.2-0.3):(0.05-0.1), and then water is added and stirred into a slurry. The water content of the slurry is 5-10%. Then, it is first treated at 350-380°C for 40-60 minutes, and then the temperature is raised to 650-700°C. After treatment for 40-60 minutes, the carbonized filler is obtained.

[0019] By adopting the above technical solution, in this application, the waste fibers and iron-containing sludge are pyrolyzed. The iron element in the iron-containing sludge acts as a catalyst to promote the fiber cracking to form an amorphous carbon precursor, and then the temperature is continuously raised to form a carbon skeleton filler. The addition of polyvinyl alcohol helps the adhesion and mixing of the waste fibers, iron-containing sludge, and starch. The addition of starch serves as a carbon skeleton source and a pore-forming agent, so that the prepared carbonized filler has a certain microporous structure. Its tiny pore structure can relieve the internal stress concentration of the concrete, and its pore structure can store a certain amount of environmental moisture and release it during drying to maintain the internal humidity of the concrete, achieving a certain degree of self-curing and improving the durability of the concrete.

[0020] Optionally, the mineral admixture is selected as nano-silica and metakaolin with a mass ratio of 1:(2-3).

[0021] By adopting the above technical solution, the mineral admixture is selected as nano-silica and metakaolin. Its pozzolanic effect and the carbon nanostructure in the carbonized filler form a three-dimensional gel network, improving the compactness of the concrete matrix and the mechanical properties.

[0022] Optionally, the coarse aggregate is selected as crushed stone with a continuous particle size of 5-15 mm, and the fine aggregate is selected as manufactured sand with a fineness modulus of 2.5-3; the admixture is selected as polycarboxylate water reducer.

[0023] In the second aspect, this application provides a preparation method of concrete prepared based on recycled fibers, adopting the following technical solution: A preparation method of concrete prepared based on recycled fibers, comprising the following steps: After mixing cement, coarse aggregate, and fine aggregate, add the carbonized filler and mineral admixture, and then add the recycled fibers after stirring to obtain a powder mixture; Mix the admixture and water and then add them to the powder mixture, and stir to obtain the concrete.

[0024] By adopting the above technical solutions, the method provided by the present application is simple, convenient and easy to industrialize, and realizes the recycling of waste.

[0025] In summary, the present application has the following beneficial effects: 1. In the present application, the recycled fiber is selected as a mixture of alkalized glass fiber scraps and modified waste textile fibers. The glass fiber scraps can significantly enhance the concrete, and the high extensibility and flexibility of cotton fibers complement the high modulus of polyester fibers to form a toughness support system in the concrete, playing a bridging role to improve the mechanical properties and crack resistance of the concrete. 2. After the waste fibers in the present application are treated in the modification liquid, the introduction of functional groups such as amino and carboxyl groups can form chemical bonding with the hydroxyl groups on the surface of glass fibers, thereby improving the connection strength of the recycled fibers. Moreover, it can also improve the interfacial bonding performance between the recycled fibers and the cement matrix, making them evenly dispersed in the cement-based material, and better playing the bridging role to delay the initiation and propagation of cracks. After being treated with the modification liquid, the sulfonic acid groups can chelate with calcium ions in cement hydration products such as calcium hydroxide to improve the interfacial bonding strength between the recycled fibers and the cement matrix. The dimethylamino group is protonated in the alkaline environment of the concrete to form cationic sites, which can be adsorbed on the surface of negatively charged cement particles, reducing fiber agglomeration and improving dispersibility. The introduction of the tertiary carbonic acid group can not only form a steric hindrance effect between the fibers to reduce agglomeration, but also improve the moisture absorption performance of cotton fibers due to its steric hindrance effect, alleviating the formation of stress and crack propagation caused by fiber shrinkage during the moisture absorption and drying of cotton fibers. Specific embodiments

[0026] The following further elaborates on the present application with reference to embodiments. It should be specifically noted that: for those not specifying specific conditions in the following embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Except for special instructions, the raw materials used in the following embodiments can all be obtained from ordinary commercial sources.

[0027] In the following embodiments, P.O 42.5 ordinary Portland cement is selected. The polycarboxylate superplasticizer is selected from the PCA®-9 series of polycarboxylate high-performance superplasticizers of Jiangsu Sobute New Materials Co., Ltd.

[0028] In the following preparation examples and examples, the waste fibers are obtained by crushing waste clothes and fabrics with a fiber opener to form waste materials with a size of 5-10 mm, then removing metal impurities by magnetic separation, and then soaking them first in 5 wt% sodium hydroxide at a soaking temperature of 50 °C for 20 min, and then soaking them in a surfactant solution of OP-10 with a mass concentration of 5% at a soaking temperature of 40 °C for 15 min, and then washing with water to remove residual chemicals, removing oil stains, colors, etc., and then dehydrating and drying to obtain waste fibers.

[0029] In the following preparation examples, the waste fibers used as raw materials for preparing modified waste textile fibers and the waste fibers in the preparation of carbonized fillers in the examples are all waste fibers prepared by the above method.

[0030] The following preparation examples are for the preparation of modified waste textile fibers: Preparation Example 1 A method for preparing modified waste textile fibers includes the following steps: 1). Treat waste fibers containing cotton fibers and polyester fibers under the conditions of a power of 180 W and an oxygen flow rate of 60 sccm for 4 min, and the oxygen plasma treatment is carried out under a vacuum degree of 15 Pa to obtain pretreated waste fibers; 2). Mix vinyl versatate, maleic anhydride and 65 wt% acetone aqueous solution according to an addition mass ratio of 1:2:3 to obtain a primary modification liquid, and then add the pretreated waste fibers after oxygen plasma treatment to the primary modification liquid. The addition mass ratio of the pretreated waste fibers to the primary modification liquid is 1:5. Add ammonium persulfate, and the addition amount of ammonium persulfate added to the primary modification liquid is 0.4 wt% of the pretreated waste fibers. Heat to 55 °C and carry out impregnation treatment at a pressure of 0.2 MPa for 50 min, and dry to obtain primary modified waste fibers; Then mix 2-acrylamido-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water according to a mass ratio of 1:1.1:7 to obtain a modified impregnation liquid, and then add the obtained primary modified waste fibers to the modified impregnation liquid. The addition mass ratio of the primary modified waste fibers to the modified impregnation liquid added with 2-acrylamido-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate is 1:5. Add ammonium persulfate, and the addition amount of ammonium persulfate added to the modified impregnation liquid is 0.8 wt% of the addition amount of the primary modified waste fibers. Then heat to 75 °C and carry out impregnation treatment at a pressure of 0.2 MPa for 50 min, and then dry to obtain modified waste textile fibers.

[0031] Preparation Example 2 A method for preparing modified waste textile fibers includes the following steps: 1), Treat the waste fibers containing cotton fibers and polyester fibers under the conditions of a power of 150 W and an oxygen flow rate of 50 sccm for 5 minutes, and the oxygen plasma treatment is carried out under a vacuum of 10 Pa to obtain pretreated waste fibers; 2), Mix vinyl versatate, maleic anhydride and 65 wt% aqueous acetone solution according to the addition mass ratio of 1:2:3 to obtain the primary modification liquid. Then add the pretreated waste fibers after oxygen plasma treatment to the primary modification liquid. The addition mass ratio of the pretreated waste fibers to the primary modification liquid is 1:4. Add ammonium persulfate, and the addition amount of ammonium persulfate added to the primary modification liquid is 0.2 wt% of the pretreated waste fibers. Heat to 50 °C and carry out impregnation treatment at a pressure of 0.2 MPa for 60 minutes. After drying, obtain the primary modified waste fibers; Then mix 2-acrylamido-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate and water according to the mass ratio of 1:1:6 to obtain the modified impregnation liquid. Then add the obtained primary modified waste fibers to the modified impregnation liquid. The addition mass ratio of the primary modified waste fibers to the modified impregnation liquid added with 2-acrylamido-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate is 1:4. Add ammonium persulfate, and the addition amount of ammonium persulfate added to the modified impregnation liquid is 0.5 wt% of the addition amount of the primary modified waste fibers. Then heat to 70 °C and carry out impregnation treatment at a pressure of 0.2 MPa for 60 minutes, and then dry to obtain the modified waste textile fibers.

[0032] Preparation Example 3 A preparation method of modified waste textile fibers, comprising the following steps: 1), Treat the waste fibers containing cotton fibers and polyester fibers under the conditions of a power of 200 W and an oxygen flow rate of 80 sccm for 3 minutes, and the oxygen plasma treatment is carried out under a vacuum of 20 Pa to obtain pretreated waste fibers; 2), Mix vinyl versatate, maleic anhydride and 65 wt% aqueous acetone solution according to the addition mass ratio of 1:3:4 to obtain the primary modification liquid. Then add the pretreated waste fibers after oxygen plasma treatment to the primary modification liquid. The addition mass ratio of the pretreated waste fibers to the primary modification liquid is 1:6. Add ammonium persulfate, and the addition amount of ammonium persulfate added to the primary modification liquid is 0.6 wt% of the pretreated waste fibers. Heat to 60 °C and carry out impregnation treatment at a pressure of 0.3 MPa for 40 minutes. After drying, obtain the primary modified waste fibers; Then, 2-acrylamido-2-methylpropanesulfonic acid, dimethylaminoethyl methacrylate, and water were mixed in a mass ratio of 1:1.2:8 to prepare a modified impregnating solution. Then, the obtained preliminarily modified waste fibers were added to the modified impregnating solution. The added mass ratio of the preliminarily modified waste fibers to the modified impregnating solution containing 2-acrylamido-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate was 1:6. Ammonium persulfate was added, and the addition amount of ammonium persulfate added to the modified impregnating solution was 1 wt% of the addition amount of the preliminarily modified waste fibers. Then, the temperature was raised to 80 °C, and after impregnation treatment at 0.3 MPa for 40 min, it was dried to obtain modified waste textile fibers.

[0033] Preparation Example 4 A method for preparing modified waste textile fibers was 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 were further added to the modified impregnating solution, and the addition amount of 4-amino-2,2-dimethylbutyric acid was 2 wt% of the preliminarily modified waste fibers, and the addition amount of N-(hydroxymethyl)acrylamide was 0.8 wt% of the preliminarily modified waste fibers.

[0034] Preparation Example 5 A method for preparing modified waste textile fibers was 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 were further added to the modified impregnating solution, and the addition amount of 4-amino-2,2-dimethylbutyric acid was 1 wt% of the preliminarily modified waste fibers, and the addition amount of N-(hydroxymethyl)acrylamide was 0.5 wt% of the preliminarily modified waste fibers.

[0035] Preparation Example 6 A method for preparing modified waste textile fibers was 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 were further added to the modified impregnating solution, and the addition amount of 4-amino-2,2-dimethylbutyric acid was 3 wt% of the preliminarily modified waste fibers, and the addition amount of N-(hydroxymethyl)acrylamide was 1 wt% of the preliminarily modified waste fibers.

[0036] Comparative Preparation Example 1 A method for preparing modified waste textile fibers was carried out according to the method in Preparation Example 1, except that in step 2), vinyl versatate was not added.

[0037] Comparative Preparation Example 2 A method for preparing modified waste textile fibers was carried out according to the method in Preparation Example 1, except that in step 2), 2-acrylamido-2-methylpropanesulfonic acid was not added.

[0038] Comparative Preparation Example 3 A preparation method of modified waste textile fibers, which is carried out according to the method in Preparation Example 1, except that dimethylaminoethyl methacrylate is replaced with KH-550 in equal amount.

[0039] Comparative Preparation Example 4 A preparation method of modified waste textile fibers, which is carried out according to the method in Preparation Example 1 without performing the treatment in step 2).

[0040] The following preparation examples are for the preparation of alkalized glass fiber scraps: Preparation Example 7 A preparation method of alkalized glass fiber scraps includes the following steps: The fiber scraps generated during the glass fiber preparation process are impregnated in a sodium hydroxide solution with a mass concentration of 12% for 10 min, and then filtered and dried to obtain alkalized glass fiber scraps.

[0041] Preparation Example 8 A preparation method of alkalized glass fiber scraps includes the following steps: The fiber scraps generated during the glass fiber preparation process are impregnated in a sodium hydroxide solution with a mass concentration of 10% for 10 min, and then filtered and dried to obtain alkalized glass fiber scraps.

[0042] Preparation Example 9 A preparation method of alkalized glass fiber scraps includes the following steps: The fiber scraps generated during the glass fiber preparation process are impregnated in a sodium hydroxide solution with a mass concentration of 15% for 5 min, and then filtered and dried to obtain alkalized glass fiber scraps.

[0043] Example 1

[0044] A preparation method of concrete based on recycled fibers includes the following steps: After mixing 480 kg of cement, 800 kg of coarse aggregate, and 550 kg of fine aggregate, 60 kg of carbonation filler and 70 kg of mineral admixture are added, and after stirring, 25 kg of recycled fibers are added to obtain a powder mixture; 4 kg of admixture is mixed with 135 kg of water and then added to the powder mixture, and stirred to obtain concrete.

[0045] Among them, the coarse aggregate is selected as crushed stone with a continuous particle size of 5-15 mm, the fine aggregate is selected as manufactured sand with a fineness modulus of 2.5-3; the admixture is selected as polycarboxylate water reducer; The mineral admixture is selected as nano-silica and metakaolin with a mass ratio of 1:2.5; The regenerated fiber is a mixture of alkalized glass fiber scraps and modified waste textile fibers with a mass ratio of 1:0.7. The alkalized glass fiber scraps are the alkalized glass fiber scraps obtained in Preparation Example 7, and the modified waste textile fibers are the modified waste textile fibers obtained in Preparation Example 1. The carbonized filler is prepared by the following method: Mix waste fibers with iron-containing sludge (iron-containing sludge with an iron content of 5 wt% formed after adding coagulants such as polyferric sulfate in water treatment), starch, and polyvinyl alcohol in a mass ratio of 1:0.15:0.25:0.08, add water and stir into a slurry with a water content of 8%. Then, first treat it at 370 °C for 50 min, then raise the temperature to 680 °C, and after treating for 50 min, the carbonized filler is obtained.

[0046] Example 2

[0047] A preparation method of concrete prepared based on regenerated fiber, comprising the following steps: Mix 450 kg of cement, 760 kg of coarse aggregate, and 500 kg of fine aggregate, add 50 kg of carbonized filler and 60 kg of mineral admixture, stir, and then add 20 kg of regenerated fiber to obtain a powder mixture; Mix 3 kg of admixture with 120 kg of water and add it to the powder mixture, and stir to obtain concrete.

[0048] Among them, the coarse aggregate is selected as crushed stone with a continuous particle size of 5 - 15 mm, the fine aggregate is selected as manufactured sand with a fineness modulus of 2.5 - 3; the admixture is selected as polycarboxylate water reducer; The mineral admixture is selected as nano-silica and metakaolin with a mass ratio of 1:2; The regenerated fiber is a mixture of alkalized glass fiber scraps and modified waste textile fibers with a mass ratio of 1:0.6. The alkalized glass fiber scraps are the alkalized glass fiber scraps obtained in Preparation Example 8, and the modified waste textile fibers are the modified waste textile fibers obtained in Preparation Example 2. The carbonized filler is prepared by the following method: Mix waste fibers with iron-containing sludge (iron-containing sludge with an iron content of 5 wt% formed after adding coagulants such as polyferric sulfate in water treatment), starch, and polyvinyl alcohol in a mass ratio of 1:0.1:0.2:0.05, add water and stir into a slurry with a water content of 5%. Then, first treat it at 350 °C for 60 min, then raise the temperature to 650 °C, and after treating for 60 min, the carbonized filler is obtained.

[0049] Example 3

[0050] A preparation method of concrete prepared based on regenerated fiber, comprising the following steps: After mixing 530 kg of cement, 850 kg of coarse aggregate, and 600 kg of fine aggregate, 80 kg of carbonized filler and 80 kg of mineral admixture were added. After stirring, 30 kg of recycled fiber was added to obtain a powder mixture; 6 kg of admixture was mixed with 150 kg of water and then added to the powder mixture, and stirred to obtain concrete.

[0051] Among them, the coarse aggregate is selected as crushed stone with a continuous particle size of 5 - 15 mm, and the fine aggregate is selected as manufactured sand with a fineness modulus of 2.5 - 3; the admixture is selected as polycarboxylate water reducer; The mineral admixture is selected as nano-silica and metakaolin with a mass ratio of 1:3; The recycled fiber is a mixture of alkali-activated glass fiber scraps and modified waste textile fibers with a mass ratio of 1:0.8. The alkali-activated glass fiber scraps are selected as the alkali-activated glass fiber scraps obtained in Preparation Example 9, and the modified waste textile fibers are selected as the modified waste textile fibers obtained in Preparation Example 3; The carbonized filler is prepared by the following method: Waste fiber, iron-containing sludge (iron-containing sludge with an iron content of 5 wt% formed after adding coagulants such as polyferric sulfate in water treatment), starch, and polyvinyl alcohol were mixed in a mass ratio of 1:0.2:0.3:0.1, and then water was added and stirred into a slurry. The water content of the slurry was 10%. Then, it was first treated at 380 °C for 40 min, and then heated to 700 °C and treated for 40 min to obtain the carbonized filler.

[0052] Examples 4 - 6 A preparation method of concrete based on recycled fiber is carried out according to the method in Example 1, except that the modified waste textile fibers are respectively selected as the modified waste textile fibers obtained in Preparation Examples 4 - 6.

[0053] Example 7

[0054] A preparation method of concrete based on recycled fiber is carried out according to the method in Example 1, except that starch is not added in the preparation step of the carbonized filler.

[0055] Comparative Example 1 A preparation method of concrete based on recycled fiber is carried out according to the method in Example 1, except that the recycled fiber is selected as alkali-activated glass fiber scraps.

[0056] Comparative Examples 2 - 5 A preparation method of concrete based on recycled fiber is carried out according to the method in Example 1, except that the modified waste textile fibers are respectively selected as the modified waste textile fibers obtained in Comparative Preparation Examples 1 - 4.

[0057] Comparative Example 6 A preparation method of concrete prepared based on recycled fibers, which is carried out according to the method in Example 1, except that no carbonization filler is added to the raw materials.

[0058] Comparative Example 7 A preparation method of concrete prepared based on recycled fibers, which is carried out according to the method in Example 1, except that the modified waste textile fibers in the recycled fibers are replaced with unmodified waste textile fibers in equal amounts.

[0059] Performance testing The concrete prepared in the examples and comparative examples of this application was tested for 28-day compressive strength and crack resistance. The compressive strength was carried out in accordance with GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and the crack resistance was carried out in accordance with GB / T 50082-2009 "Standard for Test Methods of 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.

[0060] Table 1:

[0061] Referring to the test results in Table 1 above, in the examples of this application, the combined action of recycled fibers and carbonization fillers significantly improves the compressive strength of concrete, while reducing the number and total length of cracks, and has excellent mechanical properties and crack resistance. This is because the recycled fibers form a three-dimensional disordered distribution support structure inside the concrete, enhancing the integrity and toughness of the concrete material. At the same time, the addition of carbonization fillers 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, when 4-amino-2,2-dimethylbutyric acid and N-(hydroxymethyl)acrylamide are also added to the modified impregnating solution, it helps to introduce functional groups such as amino groups into the waste fibers, change the fiber activity, and promote the chemical bonding between the fibers and the cement matrix as well as between the waste fibers and the glass fiber scraps, further improving the mechanical properties and durability of the concrete. Combining with the test results of Example 7, when the carbonization filler does not contain starch, its compressive strength decreases slightly and the crack resistance also decreases slightly. The addition of starch can not only be used as a carbon skeleton source, but also as a pore-forming agent to form a certain pore structure, providing stress buffering, and ultimately improving the crack resistance while making up for the strength loss caused by the pores.

[0062] Referring to the test results of Example 1 and Comparative Example 1, when only the alkalized glass fiber scraps are selected as the regenerated fiber, both the compressive strength and the crack resistance are significantly reduced. Combining with the test results of Comparative Examples 2-4, when vinyl versatate is not added to the modified impregnating solution, both its crack resistance and strength are reduced. In Comparative Examples 3-4, when 2-acrylamide-2-methylpropanesulfonic acid or dimethylaminoethyl methacrylate is not added, its comprehensive performance is also reduced. Combining with the test results in Comparative Example 5, when the waste fiber is only treated by oxygen plasma and not impregnated and modified by the modified solution, its performance is significantly reduced. Combining with the test results of Comparative Examples 6 and 7, when the carbonized filler is not added, its mechanical properties are reduced and the crack resistance is also slightly reduced. In Comparative Example 7, when only waste textile fibers are added, its performance is also significantly reduced.

[0063] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions according to needs, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A concrete prepared based on recycled fibers, 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 subjecting waste fibers including cotton fibers and polyester fibers to oxygen plasma treatment and impregnation with a modifying liquid, wherein the modifying liquid includes tert-butyl vinyl carbonate, maleic anhydride, 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate; The waste fibers are obtained by crushing textile waste, magnetically separating it, and then washing and desizing it.

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 oxygen plasma treatment is: treating the waste fibers for 3-5 minutes at a power of 150-200 W and an oxygen flow rate of 50-80 sccm, and the oxygen plasma treatment is carried out at a vacuum degree of 10-20 Pa 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 fiber, the specific operation of the modified liquid impregnation treatment is: first, tert-butyl vinyl carbonate, maleic anhydride and acetone solution are mixed to obtain a primary modified liquid, and then the pretreated waste fiber treated with oxygen plasma is added to the primary modified liquid, and ammonium persulfate is added, and the temperature is raised to 50-60° C., and the impregnation treatment is carried out at a pressure of 0.2-0.3 MPa for 40-60 minutes, and the primary modified waste fiber is obtained after drying; 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, ammonium persulfate is added, and then the temperature is raised to 70-80° C., and after impregnation treatment at a pressure of 0.2-0.3 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 immersion treatment, the mass ratio of tert-butyl vinyl carbonate, maleic anhydride and acetone solution is 1:(2-3):(3-4), the mass ratio of pre-treated 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 pre-treated 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 primary modified waste fiber to modified impregnation solution is 1:(4-6), and the amount of ammonium persulfate added to the modified impregnation solution is 0.5-1wt% of the amount of primary modified waste fiber added.

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 added amount of 4-amino-2,2-dimethylbutyric acid is 1-3wt% of the primary modified waste fiber, and the added amount of N-(hydroxymethyl)acrylamide 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: Carbonized fillers are prepared by the following method: 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.

8. 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).

9. 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.

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

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