Modified polyester fiber low-carbon high-strength concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete preparation, and particularly discloses modified polyester fiber low-carbon high-strength concrete and a preparation method thereof. The invention relates to modified polyester fiber low-carbon high-strength concrete, which comprises the following raw materials: 30-40 parts of cement; 15 to 25 parts of fly ash; 5-10 parts of silica fume; 10 to 15 parts of slag powder; 40 to 50 parts of quartz sand; 80 to 100 parts of broken stone; 0.1 to 0.3 part of aluminum powder; 0.8 to 1.5 parts of a water reducing agent; 1 to 1.5 parts of a defoaming agent; 1-3 parts of modified polyester fiber; 15 to 25 parts of water; 0.5 to 1.5 parts of nano calcium carbonate; the modified polyester fiber is obtained by forming an ordered nano composite layer on the surface of the polyester fiber through molecular self-assembly of nano zinc oxide particles. According to the concrete disclosed by the invention, the compressive strength and breaking strength of the concrete are remarkably improved by introducing the modified polyester fibers.

Description

Technical Field

[0001] The present application relates to the technical field of concrete preparation, and more specifically, to a modified polyester fiber low-carbon high-strength concrete and a preparation method thereof. Background Art

[0002] Concrete is a widely used material in construction projects. With the development of the construction industry, the requirements for concrete strength and other properties are constantly increasing. Ordinary concrete has certain limitations in strength and is difficult to meet the requirements of some projects with high requirements for building structure strength, such as high-rise buildings and long-span bridges.

[0003] In the related art, an application document with publication number CN108529961A discloses a green high-performance concrete material and a preparation method thereof, comprising cement, admixtures, aggregates, admixtures and water, wherein the admixtures include fly ash, silica fume and slag; the aggregates include sand and stone; the admixtures include polyester fiber / polypropylene fiber, expansion agent, water reducer, air entraining agent and steel fiber; and each raw material is prepared according to the following weight ratio: 180-250 parts of cement, 200-290 parts of fly ash, 45-80 parts of slag, 25-65 parts of silica fume, 655-695 parts of sand, 1000-1200 parts of stone, 25-65 parts of expansion agent, 3.6-4.9 parts of steel fiber, 0.4-0.9 parts of polyester fiber / polypropylene fiber, 6.6-7.9 parts of water reducer, 0.55-0.75 parts of air entraining agent and 135-155 parts of water. Cement, fly ash, slag, silica fume, sand, stone and expansion agent are weighed in parts by weight, put into a mixer, and stirred at a constant speed for 1-3 minutes to mix evenly to obtain a first mixture; steel fiber and polyester fiber / polypropylene fiber are weighed in parts by weight, and then the steel fiber and polyester fiber / polypropylene fiber are added to the first mixture, and stirred at a constant speed for 1-3 minutes to mix evenly to obtain a second mixture; water, water reducing agent and air entraining agent are taken in parts by weight, and put into the mixer in sequence, and stirred evenly to obtain a mixed solution; the mixed solution is added to the second mixture in 3-5 times, and stirred at a constant speed for 3-5 minutes to obtain a semi-finished concrete product; the semi-finished concrete product is poured into a mold for molding, and vibrated manually or mechanically for 20-30 seconds to obtain the green high-performance concrete material.

[0004] In the related art, concrete is strengthened by adding fibers such as polyester fibers. The creep deformation of polyester fibers under long-term load in concrete cannot be ignored. Creep is a slow and continuous process that causes polyester fibers to gradually elongate under stress and then undergo plastic deformation. This deformation not only reduces the strength of the fiber itself, but also affects the reinforcing effect of the fiber in concrete. For high-strength concrete, the creep deformation of the fiber may weaken its overall strength, causing the concrete to exhibit weaker compressive resistance when subjected to extreme loads.

[0005] In addition, creep deformation can weaken the bond between the glass fiber and the concrete matrix. If the bond between the fiber and the concrete is insufficient, the fiber may be pulled out of the concrete when subjected to external forces, resulting in localized strength problems in the concrete. Summary of the invention

[0006] In order to enhance the strength performance of concrete, the present application provides a modified polyester fiber low-carbon high-strength concrete and a preparation method thereof.

[0007] The modified polyester fiber low-carbon high-strength concrete provided in this application adopts the following technical solution: A modified polyester fiber low-carbon high-strength concrete, comprising the following raw materials: 30-40 parts of cement; 15-25 parts of fly ash; Silica fume 5-10 parts; 10-15 parts of slag powder; 40-50 parts of quartz sand; 80-100 parts of crushed stone; Aluminum powder 0.1-0.3 parts; Water reducing agent 0.8-1.5 parts; 1-1.5 parts of defoaming agent; 1-3 parts of modified polyester fiber; 15-25 parts water; Nano calcium carbonate 0.5-1.5 parts; The modified polyester fiber is obtained by forming an ordered nano composite layer on the surface of the polyester fiber through molecular self-assembly of nano zinc oxide particles.

[0008] By adopting the above technical scheme, silica fume and slag powder have good activity. They can refine the pore structure of concrete, fill tiny pores, improve the density of concrete, and enhance the strength and impermeability of concrete. Quartz sand and crushed stone as aggregates provide concrete with good volume stability and deformation resistance. Aluminum powder reacts with other substances in an alkaline environment to produce hydrogen, forming tiny pores, which improves the pore structure of concrete to a certain extent, making the concrete lighter and having certain thermal insulation properties. Water reducer can significantly reduce the water consumption of concrete mixtures and improve the strength of concrete while ensuring the working performance of concrete. Defoamer can effectively eliminate bubbles introduced during mixing, avoid the adverse effects of large bubbles on the concrete structure, and improve the uniformity and strength of concrete. Nano calcium carbonate has the characteristics of high activity and small particle size. It can fill in the tiny pores between cement particles, participate in the hydration reaction of cement, promote the generation and crystallization of hydration products, and further enhance the microstructure of concrete. Modified polyester fiber is a key factor in improving the strength of concrete. Nano zinc oxide particles have a high specific surface area and excellent mechanical properties, and form an ordered nanocomposite layer on the surface of polyester fibers through molecular self-assembly. The active groups on the surface of nano zinc oxide particles are chemically bonded with the groups on the surface of polyester fibers, and there are strong intermolecular forces, such as van der Waals forces. These interactions enhance the interaction between the molecular chains in the polyester fibers, making it difficult for the molecular chains of the polyester fibers to slip and deform when subjected to external forces, effectively reducing creep deformation. When concrete is subjected to stress, the modified polyester fiber can evenly distribute the load to the entire concrete matrix with its stable nanocomposite layer structure. When concrete is subjected to pressure, the modified polyester fiber can bear part of the pressure, prevent the generation and expansion of microcracks inside the concrete, thereby significantly improving the compressive strength of the concrete. When concrete is subjected to bending force, the modified polyester fiber can cross the cracks, withstand tensile stress, and improve the flexural strength of the concrete. It is like a reinforcing bar inside the concrete, which enhances the toughness and deformation capacity of the concrete, so that the concrete can better resist damage when subjected to bending loads.

[0009] Optionally, the modified polyester fiber is prepared by the following steps: A. Dissolve zinc acetate in a mixed solution of anhydrous ethanol and ethylene glycol (volume ratio 3:2), and mix under magnetic stirring to form solution A; B. Mix deionized water, anhydrous ethanol and glacial acetic acid to form solution B, take solution A and solution B at a mass ratio of 1:1, add solution B dropwise to solution A under stirring, and control the dropping speed at 1 drop / second. After the dropping is completed, continue stirring and reacting for 2-3 hours to obtain nano zinc oxide sol; C. Aging the nano zinc oxide sol at 70° C. for 12 hours, then drying at 85° C. for 12 hours, and finally calcining at 550° C. for 3 hours to obtain nano zinc oxide particles; D. Adding the nano zinc oxide particles into a toluene solution containing γ-methacryloxypropyltrimethoxysilane, wherein the concentration of γ-methacryloxypropyltrimethoxysilane is 0.15 mol / L, and reacting the solution under reflux at 85° C. for 3-6 hours. After the reaction, washing the solution with anhydrous ethanol, centrifuging and drying the solution to obtain active nano zinc oxide particles. E. Sodium dodecyl sulfate, active nano zinc oxide particles and aluminum acetylacetonate are mixed to obtain a reaction solution, and then the pH value of the reaction solution is adjusted to 7.0 with a dilute hydrochloric acid solution, and then polyester fiber is added, followed by stirring at 40-50° C. and a speed of 250 r / min for 1-3 hours to obtain modified polyester fiber.

[0010] By adopting the above technical scheme, in step A, the mixed solution of anhydrous ethanol and ethylene glycol provides a good dissolving environment for zinc acetate and can adjust the hydrolysis rate of zinc acetate. Magnetic stirring makes zinc acetate fully dissolved and evenly dispersed to form a stable solution A, which lays the foundation for subsequent reactions. In step B, deionized water participates in the hydrolysis reaction of zinc acetate, and glacial acetic acid inhibits the hydrolysis rate to avoid excessive hydrolysis leading to particle agglomeration. After aging, drying and calcination treatment in step C, the aging process promotes further growth and agglomeration of nano zinc oxide particles, making its structure more stable; drying removes moisture in the sol to prevent moisture from affecting subsequent reactions; calcination increases the crystallinity of nano zinc oxide particles, enhances their performance, and obtains high-quality nano zinc oxide particles. In step D, the nano-zinc oxide particles react with γ-methacryloxypropyltrimethoxysilane in a toluene solution, and the siloxy groups of the silane coupling agent condense with the hydroxyl groups on the surface of the nano-zinc oxide particles, successfully grafting organic groups containing double bonds on the surface of the nano-zinc oxide particles, providing active sites for subsequent self-assembly with polyester fibers.

[0011] In step E, sodium dodecyl sulfate forms a micellar structure in the solution, with its hydrophilic head in contact with water outward and its hydrophobic tail aggregated inward. When the polyester fiber is immersed in the solution, the micelles are adsorbed on the surface of the polyester fiber, changing its surface physical and chemical properties. There are various intermolecular interactions between the γ-methacryloxypropyl group on the surface of the active nano zinc oxide particles and the sodium dodecyl sulfate micelles and the surface of the polyester fiber, such as hydrogen bonds, electrostatic effects, etc. Aluminum acetylacetonate, as a catalyst, promotes these interactions, allowing the active nano zinc oxide particles to be adsorbed more quickly and stably near the surface of the polyester fiber. Under heating and stirring conditions, the active nano zinc oxide particles gradually arrange in order around the micelles on the surface of the polyester fiber. Over time, they are further fixed by chemical bonding and intermolecular forces to form a tightly bound and structurally ordered nano composite layer, which greatly enhances the performance of the polyester fiber and enables it to better play a reinforcing role in concrete.

[0012] Optionally, in step A, the mass ratio of the mixed solution of zinc acetate, anhydrous ethanol and ethylene glycol is 1:5:7.

[0013] By adopting the above technical solution, the above mass ratio ensures that zinc acetate has good solubility and dispersibility in the mixed solution, and at the same time can appropriately control the rate of the hydrolysis reaction, which is conducive to forming a uniform and stable solution system, ensuring the stable quality of the subsequently prepared nano zinc oxide sol.

[0014] Optionally, in step B, the volume ratio of deionized water, anhydrous ethanol and glacial acetic acid is 5:4:2.

[0015] By adopting the above technical solution, the above volume ratio can accurately control the balance of hydrolysis and polycondensation reaction. The appropriate amount of glacial acetic acid added effectively inhibits the agglomeration of particles, helps to prepare nano zinc oxide sol with uniform particle size and stable performance, and provides a guarantee for obtaining high-quality nano zinc oxide particles.

[0016] Optionally, in step D, the mass ratio of the nano zinc oxide particles to the toluene solution containing γ-methacryloxypropyltrimethoxysilane is 1:(4-5).

[0017] By adopting the above technical solution, this mass ratio ensures that the grafting reaction is fully carried out, so that a sufficient number of organic groups can be successfully grafted onto the surface of the nano zinc oxide particles, creating favorable conditions for subsequent self-assembly on the surface of the polyester fiber to form a stable nano-composite layer.

[0018] Optionally, in step E, the mass ratio of sodium dodecyl sulfate, active nano zinc oxide particles and aluminum acetylacetonate is 5:10:3.

[0019] By adopting the above technical solution, this mass ratio can ensure the formation of a uniform and dense nanocomposite layer on the surface of the polyester fiber. Under this ratio, the sodium dodecyl sulfate micelles can effectively guide the adsorption and arrangement of active nano zinc oxide particles, and aluminum acetylacetonate can fully exert its catalytic effect, thereby enhancing the creep resistance of the polyester fiber and improving its reinforcement effect in concrete.

[0020] Optionally, the defoamer is any one of a silicone defoamer, a polyether defoamer, and a mineral oil defoamer.

[0021] By adopting the above technical solution, the above defoaming agent can effectively eliminate the bubbles generated during the concrete mixing process, optimize the pore structure of the concrete, reduce the adverse effects of harmful pores on the strength of the concrete, and synergize with other components to improve the comprehensive performance of the concrete.

[0022] Optionally, the particle size of the nano calcium carbonate is 300-500nm.

[0023] By adopting the above technical solution, nano calcium carbonate in this particle size range has a large specific surface area and high activity. In concrete, it can fill the tiny pores between cement particles, participate in the hydration reaction of cement, promote the formation and crystallization of hydration products, refine the microstructure of concrete, improve the density and strength of concrete, and enhance the impermeability and durability of concrete.

[0024] The present application also provides a method for preparing modified polyester fiber low-carbon high-strength concrete, which adopts the following technical solution: A method for preparing modified polyester fiber low-carbon high-strength concrete comprises the following steps: S1. Mixing the modified polyester fiber with water and stirring for 5-10 minutes to obtain a fiber suspension; S2. Add cement, fly ash, silica fume, slag powder, quartz sand, crushed stone, aluminum powder, water reducer, and nano calcium carbonate into a mixer, stir for 5-10 minutes, then add the fiber suspension, and continue stirring for 10-15 minutes to obtain modified polyester fiber low-carbon high-strength concrete.

[0025] In summary, this application has the following beneficial effects: 1. This application significantly improves the compressive strength and flexural strength of concrete by introducing modified polyester fibers. The nanocomposite layer on the surface of the modified polyester fibers enhances the bonding force between the polyester fibers and the concrete matrix, while improving the creep resistance of the polyester fibers themselves. When concrete is subjected to pressure and bending forces, the modified polyester fibers can effectively disperse stress and avoid structural damage caused by stress concentration, thereby greatly improving the compressive and flexural strength of concrete, making the concrete perform better when subjected to heavy loads and complex stress environments.

[0026] 2. This application optimizes the microstructure of concrete by precisely controlling the raw material ratio and preparation process. The raw materials work together, fly ash, silica fume, slag powder and nano calcium carbonate refine and fill the pore structure, and the defoamer eliminates harmful bubbles, so that the density and uniformity of the concrete are improved. The reasonable raw material ratio creates good conditions for the uniform distribution of modified polyester fiber in concrete, further improving the strength performance of concrete.

[0027] 3. The preparation process of the modified polyester fiber low-carbon high-strength concrete of the present application is simple and efficient, with a wide range of raw materials and controllable costs. During the preparation process, after the raw materials are mixed in proportion, a high-performance concrete material can be prepared through a simple mixing process. Although the preparation process of the modified polyester fiber involves multiple steps, the operation is relatively simple and suitable for industrial production. This preparation process not only reduces production costs, but also improves production efficiency, making the material have broad application prospects in the field of construction engineering. DETAILED DESCRIPTION

[0028] The present application is further described in detail below with reference to the embodiments.

[0029] Preparation example of modified polyester fiber Preparation Example 1 The modified polyester fiber is prepared by the following steps: A. Dissolve 10 g of zinc acetate in a mixed solution of 50 g of anhydrous ethanol and 70 g of ethylene glycol and stir at a speed of 500 r / min for 30 min under magnetic stirring to form solution A; B. Mix 5 mL of deionized water, 4 mL of anhydrous ethanol and 2 mL of glacial acetic acid to form solution B. Take 10 g of solution A and 10 g of solution B respectively. Add solution B dropwise to solution A under stirring at 200 r / min. The dropping speed is controlled at 1 drop / second. After the dropping is completed, continue stirring and reacting for 2 hours to obtain nano zinc oxide sol; C. Aging the nano zinc oxide sol at 70° C. for 12 hours, then drying at 85° C. for 12 hours, and finally calcining at 550° C. for 3 hours to obtain nano zinc oxide particles; D. Add 10g of nano zinc oxide particles to 40g of toluene solution containing γ-methacryloxypropyltrimethoxysilane (concentration of 0.15mol / L), and reflux at 85°C for 3h. After the reaction, wash with anhydrous ethanol 3 times, 10min each time, then centrifuge at 5000r / min for 5min, and then dry at 60°C for 6h to obtain active nano zinc oxide particles; E. Weigh 5 g of sodium dodecyl sulfate, 10 g of active nano zinc oxide particles and 3 g of aluminum acetylacetonate to obtain a reaction solution, adjust the pH value of the reaction solution to 7.0 with a dilute hydrochloric acid solution, then add 5 g of polyester fiber, and then stir the reaction at 40° C. and 250 r / min for 1 h to obtain modified polyester fiber.

[0030] Preparation Example 2 The modified polyester fiber is prepared by the following steps: A. Dissolve 10 g of zinc acetate in a mixed solution of 50 g of anhydrous ethanol and 70 g of ethylene glycol, and stir at a speed of 500 r / min for 30 min under magnetic stirring to form solution A; B. Mix 5 mL of deionized water, 4 mL of anhydrous ethanol and 2 mL of glacial acetic acid to form solution B. Take 10 g of solution A and 10 g of solution B respectively. Add solution B dropwise to solution A under stirring at 200 r / min. The dropping speed is controlled at 1 drop / second. After the dropping is completed, continue stirring and reacting for 2.5 hours to obtain nano zinc oxide sol; C. Aging the nano zinc oxide sol at 70° C. for 12 hours, then drying at 85° C. for 12 hours, and finally calcining at 550° C. for 3 hours to obtain nano zinc oxide particles; D. Add 10g of nano zinc oxide particles to 45g of toluene solution containing γ-methacryloxypropyltrimethoxysilane (concentration of 0.15mol / L), and reflux at 85°C for 4.5h. After the reaction, wash with anhydrous ethanol 3 times, 10min each time, then centrifuge at 5000r / min for 5min, and then dry at 60°C for 6h to obtain active nano zinc oxide particles; E. Weigh 5 g of sodium dodecyl sulfate, 10 g of active nano zinc oxide particles and 3 g of aluminum acetylacetonate to obtain a reaction solution, adjust the pH value of the reaction solution to 7.0 with a dilute hydrochloric acid solution, then add 5 g of polyester fiber, and then stir the reaction at 45° C. and 250 r / min for 2 h to obtain modified polyester fiber.

[0031] Preparation Example 3 The modified polyester fiber is prepared by the following steps: A. Dissolve 10 g of zinc acetate in a mixed solution of 50 g of anhydrous ethanol and 70 g of ethylene glycol, and stir at a speed of 500 r / min for 30 min under magnetic stirring to form solution A; B. Mix 5 mL of deionized water, 4 mL of anhydrous ethanol and 2 mL of glacial acetic acid to form solution B. Take 10 g of solution A and 10 g of solution B respectively. Add solution B dropwise to solution A under stirring at 200 r / min. The dropping speed is controlled at 1 drop / second. After the dropping is completed, continue stirring and reacting for 3 hours to obtain nano zinc oxide sol; C. Aging the nano zinc oxide sol at 70° C. for 12 hours, then drying at 85° C. for 12 hours, and finally calcining at 550° C. for 3 hours to obtain nano zinc oxide particles; D. Add 10g of nano zinc oxide particles to 50g of toluene solution containing γ-methacryloxypropyltrimethoxysilane (concentration of 0.15mol / L), and reflux at 85°C for 6h. After the reaction, wash with anhydrous ethanol 3 times, 10min each time, then centrifuge at 5000r / min for 5min, and then dry at 60°C for 6h to obtain active nano zinc oxide particles; E. Weigh 5 g of sodium dodecyl sulfate, 10 g of active nano zinc oxide particles and 3 g of aluminum acetylacetonate to obtain a reaction solution, adjust the pH value of the reaction solution to 7.0 with a dilute hydrochloric acid solution, then add 5 g of polyester fiber, and then stir the reaction at 50° C. and 250 r / min for 3 h to obtain modified polyester fiber.

[0032] Preparation Example 4 The difference between the modified polyester fiber and Preparation Example 3 is that aluminum acetylacetonate is not added in step E of this comparative example. Specifically, step E is as follows: Weigh 5 g of sodium dodecyl sulfate and 10 g of active nano zinc oxide particles to obtain a reaction solution, adjust the pH value of the reaction solution to 7.0 with a dilute hydrochloric acid solution, then add 5 g of polyester fiber, and then stir the reaction at 50° C. and 250 r / min for 3 hours to obtain modified polyester fiber.

[0033] The other steps are the same as those in Preparation Example 3.

[0034] Preparation Example 5 The modified polyester fiber is different from Preparation Example 3 in that step D is not performed in this comparative example, that is, the nano zinc oxide particles are not activated, and the nano zinc oxide particles are directly used to participate in the reaction in the subsequent step E. The other preparation steps are the same as those in Preparation Example 3.

[0035] Preparation Example 6 The modified polyester fiber is different from Preparation Example 3 in that the reaction solution in step E of this Preparation Example is stirred at 250 r / min for 3 hours at 30° C. to obtain the modified polyester fiber, and the other preparation steps are the same as Preparation Example 3. Example Example 1

[0036] A modified polyester fiber low-carbon high-strength concrete, whose raw material components and dosages are shown in Table 1, wherein the defoaming agent is an organosilicon defoaming agent, the water reducer is a polycarboxylic acid high-efficiency water reducer, the particle size of nano calcium carbonate is 300nm, and the modified polyester fiber is the modified polyester fiber prepared in Preparation Example 1.

[0037] A modified polyester fiber low-carbon high-strength concrete, the preparation method of which is as follows: S1, mixing the modified polyester fiber with water and stirring for 5 minutes to obtain a fiber suspension; S2. Add cement, fly ash, silica fume, slag powder, quartz sand, crushed stone, aluminum powder, water reducer, and nano calcium carbonate into a mixer and stir for 5 minutes. Then add the fiber suspension and continue stirring for 10 minutes to obtain modified polyester fiber low-carbon high-strength concrete. Example 2

[0038] A modified polyester fiber low-carbon high-strength concrete, whose raw material components and dosages are shown in Table 1, wherein the defoaming agent is a polyether defoaming agent, the water reducer is a polycarboxylic acid high-efficiency water reducer, the particle size of nano calcium carbonate is 400nm, and the modified polyester fiber is the modified polyester fiber prepared in Preparation Example 2.

[0039] A modified polyester fiber low-carbon high-strength concrete, the preparation method of which is as follows: S1, mixing the modified polyester fiber with water and stirring for 7 minutes to obtain a fiber suspension; S2. Add cement, fly ash, silica fume, slag powder, quartz sand, crushed stone, aluminum powder, water reducer, and nano calcium carbonate into a mixer and stir for 7 minutes. Then add the fiber suspension and continue stirring for 12 minutes to obtain modified polyester fiber low-carbon high-strength concrete. Example 3

[0040] A modified polyester fiber low-carbon high-strength concrete, whose raw material components and dosages are shown in Table 1, wherein the defoaming agent is a mineral oil defoaming agent, the water reducer is a polycarboxylic acid high-efficiency water reducer, the particle size of nano calcium carbonate is 500nm, and the modified polyester fiber is the modified polyester fiber prepared in Preparation Example 3.

[0041] A modified polyester fiber low-carbon high-strength concrete, the preparation method of which is as follows: S1, mixing the modified polyester fiber with water and stirring for 10 minutes to obtain a fiber suspension; S2. Add cement, fly ash, silica fume, slag powder, quartz sand, crushed stone, aluminum powder, water reducer, and nano calcium carbonate into a mixer and stir for 10 minutes. Then add the fiber suspension and continue stirring for 15 minutes to obtain modified polyester fiber low-carbon high-strength concrete.

[0042] Table 1 Raw material components and amounts of concrete in Examples 1-3 (g) raw material Example 1 Example 2 Example 3 cement 30 35 40 Fly ash 15 20 25 Silica Fume 5 7 10 Slag powder 10 12 15 Quartz sand 40 45 50 gravel 80 90 100 Aluminum powder 0.1 0.2 0.3 Water reducing agent 0.8 1.2 1.5 Defoaming agent 1 1.2 1.5 Modified polyester fiber 1 2 3 water 15 20 25 Nano Calcium Carbonate 0.5 1 1.5 Example 4

[0043] A modified polyester fiber low-carbon high-strength concrete, which is different from Example 1 in that the modified polyester fiber in this example is the modified polyester fiber prepared in Preparation Example 4. Example 5

[0044] A modified polyester fiber low-carbon high-strength concrete, which is different from Example 1 in that the modified polyester fiber in this example is the modified polyester fiber prepared in Preparation Example 5. Example 6

[0045] A modified polyester fiber low-carbon high-strength concrete, which is different from Example 1 in that the modified polyester fiber in this example is the modified polyester fiber prepared in Preparation Example 6.

[0046] Comparative Example Comparative Example 1 A modified polyester fiber low-carbon high-strength concrete is different from Example 1 in that an equal amount of unmodified polyester fiber is used instead of the modified polyester fiber in this comparative example.

[0047] Comparative Example 2 A modified polyester fiber low-carbon high-strength concrete, which is different from Example 1 in that nano calcium carbonate is not added in this comparative example.

[0048] Comparative Example 3 A modified polyester fiber low-carbon high-strength concrete, which is different from Example 1 in that the amount of modified polyester fiber used in this comparative example is 5g.

[0049] Performance testing Compressive strength test Test object: concrete prepared in Examples 1-6 and Comparative Examples 1-3.

[0050] Test method: According to GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", the prepared concrete is cast into a 150mm×150mm×150mm cubic specimen, cured for 28 days under standard curing conditions (temperature 20±2℃, relative humidity above 95%), and then loaded on a pressure testing machine at a specified loading speed until the specimen is destroyed. The failure load is recorded and the compressive strength is calculated.

[0051] Test results: See Table 2.

[0052] Flexural strength test Test object: concrete prepared in Examples 1-6 and Comparative Examples 1-3.

[0053] Test method: According to GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", cast concrete into 150mm×150mm×600mm (or 550mm) prism specimens, cure them for 28 days under standard curing conditions, use a three-point loading method, load them on a flexural testing machine, record the load when the specimen is destroyed, and calculate the flexural strength.

[0054] Test results: See Table 2.

[0055] Table 2 Test results project Compressive strength (MPa) Flexural strength (MPa) Example 1 65.3 7.8 Example 2 64.8 7.6 Example 3 64.5 7.5 Example 4 52.5 6.0 Example 5 48.0 5.5 Example 6 50.2 5.8 Comparative Example 1 40.0 4.0 Comparative Example 2 58.0 6.5 Comparative Example 3 55.0 6.2 The modified polyester fibers prepared using the complete process in Examples 1-3 function effectively in concrete. From the perspective of enhanced strength, the nanocomposite layer on the surface of the modified polyester fiber enhances the force between the molecular chains and reduces the creep deformation of the polyester fiber. When concrete is subjected to stress, it can continuously disperse stress, which is directly reflected in the compressive strength and flexural strength. In Example 1, the raw materials work well together, nano-calcium carbonate fills the pores, the modified polyester fibers are evenly distributed, the compressive strength reaches 65.3MPa, and the flexural strength reaches 7.8MPa. Although the raw material ratios in Examples 2 and 3 are changed, they still maintain relatively high performance, indicating that raw material adjustments within a reasonable range will not affect the core role of the modified polyester fiber in enhancing performance.

[0056] In Example 4, aluminum acetylacetonate was not added when preparing the modified polyester fiber. Aluminum acetylacetonate can promote the interaction between the active nano zinc oxide particles and the surface of the polyester fiber during the modification process. Without aluminum acetylacetonate, the nanocomposite layer is not formed perfectly, resulting in a significant reduction in the reinforcing effect of the modified polyester fiber, causing the compressive strength of the concrete to drop to 52.5 MPa and the flexural strength to drop to 6.0 MPa.

[0057] In Example 5, organic group grafting was not performed on the nano zinc oxide particles. Organic group grafting is a key step to provide active sites for subsequent self-assembly. Without organic group grafting, it is difficult for the nano zinc oxide particles to form a stable bond with the polyester fibers, and the performance of the polyester fibers cannot be effectively enhanced. The final compressive strength of the concrete is only 48.0 MPa, and the flexural strength is 5.5 MPa.

[0058] In Example 6, when preparing the modified polyester fiber, the temperature of the reaction solution in step E was 30°C, which was lower than the normal range. The lower temperature affected the orderly arrangement and chemical bonding of the nano zinc oxide particles on the surface of the polyester fiber, making the nano composite layer structure not tight enough, resulting in a concrete compressive strength of 50.2 MPa and a flexural strength of 5.8 MPa.

[0059] Comparative Example 1 uses unmodified polyester fibers, and no nanocomposite layer is formed, which cannot effectively strengthen concrete. Polyester fibers are prone to creep under long-term stress and cannot disperse stress well, so the compressive strength is only 40.0 MPa and the flexural strength is 4.0 MPa.

[0060] In Comparative Example 2, nano-calcium carbonate was not added, and the internal pore structure of the concrete was not effectively optimized, resulting in a decrease in compressive strength and flexural strength. The compressive strength was 58.0 MPa and the flexural strength was 6.5 MPa.

[0061] Although modified polyester fiber is used in Comparative Example 3, the amount is increased to 5 parts. Too much modified polyester fiber may be unevenly dispersed in the concrete, affecting the uniformity of the overall structure, resulting in a compressive strength of 55.0 MPa and a flexural strength of 6.2 MPa, both lower than those of Examples 1-3.

[0062] In summary, through the analysis of the performance test results of each embodiment and comparative example, it is fully verified that the present application can significantly improve the compressive strength and flexural strength of concrete by modifying the polyester fiber, as well as a reasonable raw material ratio and preparation process.

[0063] 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 modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A modified polyester fiber low-carbon high-strength concrete, characterized in that: The raw materials include the following components: 30-40 parts of cement; 15-25 parts of fly ash; Silica fume 5-10 parts; 10-15 parts of slag powder; 40-50 parts of quartz sand; 80-100 parts of crushed stone; Aluminum powder 0.1-0.3 parts; Water reducing agent 0.8-1.5 parts; Defoaming agent 1-1.5 parts; 1-3 parts of modified polyester fiber; 15-25 parts water; Nano calcium carbonate 0.5-1.5 parts; The modified polyester fiber is obtained by forming an ordered nano composite layer on the surface of the polyester fiber through molecular self-assembly of nano zinc oxide particles.

2. The modified polyester fiber low-carbon high-strength concrete according to claim 1, characterized in that: The modified polyester fiber is prepared by the following steps: A. Dissolve zinc acetate in a mixed solution of anhydrous ethanol and ethylene glycol (volume ratio 3:2), and mix under magnetic stirring to form solution A; B. Mix deionized water, anhydrous ethanol and glacial acetic acid to form solution B, take solution A and solution B at a mass ratio of 1:1, add solution B dropwise to solution A under stirring, and control the dropping speed at 1 drop / second. After the dropping is completed, continue stirring and reacting for 2-3 hours to obtain nano zinc oxide sol; C. Aging the nano zinc oxide sol at 70° C. for 12 hours, then drying at 85° C. for 12 hours, and finally calcining at 550° C. for 3 hours to obtain nano zinc oxide particles; D. Adding the nano zinc oxide particles into a toluene solution containing γ-methacryloxypropyltrimethoxysilane, wherein the concentration of γ-methacryloxypropyltrimethoxysilane is 0.15 mol / L, and reacting the solution under reflux at 85° C. for 3-6 hours. After the reaction, washing the solution with anhydrous ethanol, centrifuging and drying the solution to obtain active nano zinc oxide particles. E. Sodium dodecyl sulfate, active nano zinc oxide particles and aluminum acetylacetonate are mixed to obtain a reaction solution, and then the pH value of the reaction solution is adjusted to 7.0 with a dilute hydrochloric acid solution, and then polyester fiber is added, followed by stirring at 40-50° C. and a speed of 250 r / min for 1-3 hours to obtain modified polyester fiber.

3. The modified polyester fiber low-carbon high-strength concrete according to claim 2, characterized in that: The mass ratio of the zinc acetate, anhydrous ethanol and ethylene glycol mixed solution in step A is 1:5:

7.

4. The modified polyester fiber low-carbon high-strength concrete according to claim 2, characterized in that: In step B, the volume ratio of deionized water, anhydrous ethanol and glacial acetic acid is 5:4:

2.

5. The modified polyester fiber low-carbon high-strength concrete according to claim 2, characterized in that: In the step D, the mass ratio of the nano zinc oxide particles to the toluene solution containing γ-methacryloxypropyltrimethoxysilane is 1:(4-5).

6. The modified polyester fiber low-carbon high-strength concrete according to claim 2, characterized in that: In the step E, the mass ratio of sodium dodecyl sulfate, active nano zinc oxide particles and aluminum acetylacetonate is 5:10:

3.

7. The modified polyester fiber low-carbon high-strength concrete according to claim 1, characterized in that: The defoamer is any one of an organosilicon defoamer, a polyether defoamer and a mineral oil defoamer.

8. The modified polyester fiber low-carbon high-strength concrete according to claim 1, characterized in that: The particle size of the nano calcium carbonate is 300-500nm.

9. A method for preparing the modified polyester fiber low-carbon high-strength concrete according to any one of claims 1 to 8, characterized in that: The steps include: S1. Mixing the modified polyester fiber with water and stirring for 5-10 minutes to obtain a fiber suspension; S2. Add cement, fly ash, silica fume, slag powder, quartz sand, crushed stone, aluminum powder, water reducer, and nano calcium carbonate into a mixer, stir for 5-10 minutes, then add the fiber suspension, and continue stirring for 10-15 minutes to obtain modified polyester fiber low-carbon high-strength concrete.