Polyester fiber concrete material and preparation method thereof

Abstract

The invention discloses a polyester fiber concrete material and a preparation method thereof, and relates to the technical field of concrete, the polyester fiber concrete material comprises: a powder material formed by mixing cement, fly ash, sandstone and regenerated PET fiber; the water material is composed of water and a water reducing agent or water; wherein the mixing mass ratio of the cement to the fly ash to the sandstone to the regenerated PET fiber is 300 to (95 to 105) to (1100 to 1200) to (0.8 to 2.2); the regenerated PET fiber is prepared by cleaning and activating regenerated PET fiber and performing nano silicon dioxide internal strengthening and / or surface core-shell structure coating modification in sequence. According to the polyester fiber concrete material, modification of the regenerated PET fibers is realized through polymer nano-compounding, so that the interface bonding effect of the regenerated PET fibers in the polyester fiber concrete material is improved, and the problem of insufficient stress transmission caused by reduction of the cross sectional area of the regenerated PET fibers is solved; the effect that the strength requirement of concrete is met while the bending strength is remarkably improved is achieved.

Description

Technical Field

[0001] This application relates to the field of concrete technology, and in particular to a polyester fiber concrete material and its preparation method. Background Technology

[0002] Polyester (PET) fiber, due to its high strength and good chemical stability, can be recycled from waste plastic bottles, making it an ideal reinforcing fiber for concrete. PET fiber is stronger and cheaper than traditional polypropylene fiber, which is beneficial for resource recycling. However, its application in cement-based materials is still relatively limited.

[0003] In existing technologies, plasma treatment, especially cold plasma treatment, is commonly used to address issues such as poor hydrophilicity and difficulty in mixing and dispersing at the fiber-matrix interface. This process increases the surface roughness of the fiber without damaging it, activating polar groups and making the fiber more hydrophilic, thereby improving the bond performance between the fiber and the cement matrix. For virgin PET fibers, plasma treatment enhances the adhesion between the fiber and the surrounding matrix. In four-point bending tests, the specimens exhibit more significant strain hardening, with improved compressive and flexural strength, preventing excessive and sudden cracking and limiting crack opening. However, for recycled PET fibers, the reduced cross-sectional area after treatment decreases their tensile stress transfer capacity, potentially leading to gradual softening of the specimen during four-point bending and a decrease in flexural strength. This makes it difficult to effectively utilize them in concrete for reinforcement, and further improvements are needed. Summary of the Invention

[0004] In view of this, the first objective of this application is to provide a polyester fiber reinforced concrete material to effectively improve tensile crack resistance and durability. The specific solution is as follows: A polyester fiber reinforced concrete material, comprising: The powder is composed of a mixture of cement, fly ash, sand, gravel, and recycled PET fibers. Water-based materials consist of water and water-reducing agents or water; The mixing mass ratio of the cement, fly ash, sand and gravel and recycled PET fiber is 300:95-105:1100-1200:0.8-2.2. The recycled PET fiber is prepared by sequentially cleaning and activating recycled PET fiber, followed by internal reinforcement with nano-silica and / or surface core-shell structure coating modification.

[0005] Preferably, the cement is grade 42.5 high-strength silicate cement.

[0006] Preferably, the sand and gravel is composed of gravel with a particle size of 5-15mm and medium sand.

[0007] Preferably, the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0008] Preferably, the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 58-62℃ for 35-45 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain cleaned and activated fibers.

[0009] Preferably, the internal reinforcement of the nano-silica includes the following steps: Step ① Selecting nano-SiO2 with a particle size of 18-22nm and adding 2% by mass of silane coupling agent KH-550 to a mixer for mixing and stirring to obtain modified nano-SiO2 with surface-grafted amino active groups; Step ② Adding the modified nano-SiO2 and cleaned and activated recycled PET fibers to an extruder for melt extrusion at a mass ratio of 0.076-0.082:1, controlling the melt temperature at 270℃ and the stirring speed at 300r / min to obtain composite fibers with a diameter of 0.019-0.021mm; Step ③ Stretching the composite fibers three times and heat-setting them at 120℃ for 10min to obtain reinforced and shaped fibers.

[0010] Preferably, the method further includes pre-cooling the reinforced and shaped fiber in an environment with a temperature of -5°C for 5 minutes, and then feeding it into a calendering roller with a wavelength of 0.8 mm and a wave height of 0.003 mm on the surface, controlling the feeding speed to be 5 m / min, to obtain a shaped fiber with a regular corrugated surface; and the corrugation depth of the regular corrugated surface is less than or equal to 0.002 mm.

[0011] Preferably, the surface core-shell structure coating modification includes: Step ① mixing nano-CaCO3 with a particle size of 50±5nm with deionized water, and ultrasonically dispersing to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier; Step ③ adding 0.5% by mass of... Water-reducing agent and deionized water are used to obtain a shell-core modifier with a solid content of 30±1%; Step ④: Regenerated PET fibers that have been cleaned and activated or internally reinforced with nano-silica are immersed in the shell-core modifier and ultrasonically treated to obtain coated fibers; Step ⑤: The coated fibers are placed in an environment with a temperature of 80±2℃ for 30 minutes to obtain continuously coated fibers; Step ⑥: The continuously coated fibers are immersed in a KH-550-ethanol solution with a mass fraction of 0.5% and the immersion time is controlled to be 5 minutes. After removal, they are naturally air-dried to obtain modified fibers.

[0012] Preferably, in step ②, the cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for a continuous stirring time of 20 min; in step ③, the water-reducing agent is a polycarboxylate superplasticizer.

[0013] A second objective of this invention is to provide a method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0014] As can be seen from the above solutions, this application provides a polyester fiber concrete material and its preparation method, which have the following beneficial effects: 1. By modifying recycled PET fibers through polymer nanocomposites, the interfacial bonding effect of recycled PET fibers in the polyester fiber concrete material is improved, and the problem of insufficient stress transfer caused by the reduction of cross-sectional area of ​​recycled PET fibers is reduced, so as to achieve the effect of significantly improving flexural strength while meeting the strength requirements of concrete. 2. The cleaning and activation treatment of recycled PET fibers by etching with NaOH solution will form a micro-concave structure on the surface of the recycled PET fibers, thereby increasing the specific surface area. In conjunction with the internal reinforcement of nano-silica, the structure of the recycled PET fibers will be more compact and will effectively increase the number of physical meshing points. The core-shell structure coating based on nano-CaCO3 core-gel-shell modifier forms a core-shell structure, which improves the fusion effect between the surface of the recycled PET fibers and the powder, significantly reduces the interface defects between the recycled PET fibers and the powder, thereby improving the structural strength of the polyester fiber concrete material. 3. The strength of recycled PET fibers is significantly improved by strengthening and stretching through nano-silica, and the interfacial bonding force is effectively improved. This enables the recycled PET fibers to effectively transfer stress and inhibit crack propagation in the polyester fiber concrete material. When the polyester fiber concrete material is subjected to external forces, the recycled PET fibers achieve an effective bridging effect, reducing the generation and development of cracks. This effectively improves the compressive, tensile, and impact toughness of the polyester fiber concrete material and reduces the risk of brittle fracture. 4. By processing waste PET materials into recycled PET fibers and applying them to polyester fiber concrete, the environmental problems of waste PET materials are effectively solved, resource recycling is achieved, and through effective modification treatment, the problems of poor compatibility and limited reinforcing effect between recycled PET fibers and the powder of polyester fiber concrete are overcome, so that recycled PET fibers can effectively improve the mechanical and chemical properties of polyester fiber concrete. Detailed Implementation

[0015] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0016] It should be mentioned that the cement in this application is 42.5 grade high-strength silicate cement. The aggregate consists of gravel with a particle size of 5-15mm and medium sand. The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0017] The following will provide a detailed description of a polyester fiber concrete material and its preparation method according to this application.

[0018] A polyester fiber concrete material includes a powder and a liquid component. The powder is composed of cement, fly ash, sand, and recycled PET fibers. The liquid component is composed of water and a water-reducing agent or water. The mass ratio of cement, fly ash, sand, and recycled PET fibers is 300:95-105:1100-1200:0.8-2.2. The recycled PET fibers are prepared by sequentially cleaning and activating recycled PET fibers, followed by internal reinforcement with nano-silica and / or surface core-shell structure coating modification.

[0019] It should be noted that the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 58-62℃ for 35-45 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in 3% dilute hydrochloric acid for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

[0020] The internal reinforcement of nano-silica includes step ① selecting nano-SiO2 with a particle size of 18-22nm and adding 2% by mass of silane coupling agent KH-550 to a mixer for mixing and stirring to obtain modified nano-SiO2 with surface-grafted amino active groups; step ② feeding the modified nano-SiO2 and cleaned and activated recycled PET fibers into an extruder at a mass ratio of 0.076-0.082:1 for melt extrusion, controlling the melt temperature at 270℃ and the stirring speed at 300r / min to obtain straight... The composite fiber has a diameter of 0.019-0.021 mm; Step ③ stretches the composite fiber three times and heat-sets it at 120℃ for 10 minutes to obtain reinforced and shaped fiber; Step ④ pre-cools the reinforced and shaped fiber in an environment at -5℃ for 5 minutes, and then feeds it into a calendering roller with a wavelength of 0.8 mm and a wave height of 0.003 mm on the surface, controlling the feeding speed at 5 m / min to obtain a shaped fiber with a regular corrugated surface; and the corrugation depth of the regular corrugated surface is less than or equal to 0.002 mm.

[0021] The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with deionized water at a particle size of 50±5nm and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier. The cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for 20 min; Step ③ Adding nano-C... Add 0.5% by mass of polycarboxylate superplasticizer and deionized water to the aCO3 core-gel shell modifier to obtain a shell-core modifier with a solid content of 30±1%; Step ④ Immerse the cleaned and activated or nano-silica reinforced recycled PET fibers in the shell-core modifier, and obtain coated fibers after ultrasonic treatment; Step ⑤ Place the coated fibers in an environment with a temperature of 80±2℃ for 30 min to dry and obtain continuous coated fibers; Step ⑥ Immerse the continuous coated fibers in a 0.5% by mass KH-550-ethanol solution, control the immersion time to 5 min, and air dry naturally after removal to obtain modified fibers.

[0022] A method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0023] Example 1 A polyester fiber concrete material includes a powder and a liquid component. The powder is composed of cement, fly ash, sand, and recycled PET fibers. The liquid component consists of water and a water-reducing agent. The mass ratio of cement, fly ash, sand, and recycled PET fibers is 300:95:1100:0.8. The recycled PET fibers are prepared by sequentially cleaning and activating recycled PET fibers, followed by internal reinforcement modification with nano-silica.

[0024] It should be noted that the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 58℃ for 35 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

[0025] The internal reinforcement of nano-silica includes step ① selecting nano-SiO2 with an average particle size of 18nm and adding 2% by mass of silane coupling agent KH-550 to a mixer for mixing and stirring to obtain modified nano-SiO2 with surface-grafted amino active groups; step ② feeding the modified nano-SiO2 and cleaned and activated recycled PET fibers into an extruder at a mass ratio of 0.076:1 for melt extrusion, controlling the melt temperature at 270℃ and the stirring speed at 300r / min to obtain a diameter of 0. 0.19-0.021mm composite fiber; Step ③ stretch the composite fiber 3 times, heat set it at 120℃ for 10 minutes to obtain reinforced and shaped fiber; Step ④ place the reinforced and shaped fiber in an environment of -5℃ for 5 minutes to pre-cool, and then feed it into a calendering roller with a wavelength of 0.8mm and a wave height of 0.003mm, and control the feeding speed to 5m / min to obtain a shaped fiber with a regular corrugated surface; and the corrugation depth of the regular corrugated surface is less than or equal to 0.002mm.

[0026] A method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0027] Example 2 A polyester fiber concrete material includes a powder and a liquid component. The powder is composed of cement, fly ash, sand, and recycled PET fibers. The liquid component consists of water and a water-reducing agent. The mass ratio of cement, fly ash, sand, and recycled PET fibers is 300:100:1150:1.2. The recycled PET fibers are prepared by sequentially cleaning and activating recycled PET fibers, followed by internal reinforcement modification with nano-silica.

[0028] It should be noted that the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 60℃ for 40 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

[0029] The internal reinforcement of nano-silica includes step ① selecting nano-SiO2 with a particle size of 18-22nm and adding 2% by mass of silane coupling agent KH-550 to a mixer for mixing and stirring to obtain modified nano-SiO2 with surface-grafted amino active groups; step ② feeding the modified nano-SiO2 and cleaned and activated recycled PET fibers into an extruder at a mass ratio of 0.080:1 for melt extrusion, controlling the melt temperature at 270℃ and the stirring speed at 300r / min to obtain nano-SiO2 with a diameter of 0. 0.019-0.021mm composite fiber; Step ③ stretch the composite fiber 3 times, heat set it at 120℃ for 10 minutes to obtain reinforced and shaped fiber; Step ④ place the reinforced and shaped fiber in an environment of -5℃ for 5 minutes to pre-cool, and then feed it into a calendering roller with a wavelength of 0.8mm and a wave height of 0.003mm, and control the feeding speed at 5m / min to obtain a shaped fiber with a regular corrugated surface; and the corrugation depth of the regular corrugated surface is less than or equal to 0.002mm.

[0030] A method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0031] Example 3 A polyester fiber concrete material includes a powder and a liquid component. The powder is composed of cement, fly ash, sand, and recycled PET fibers. The liquid component consists of water and a water-reducing agent. The mass ratio of cement, fly ash, sand, and recycled PET fibers is 300:105:1200:2.2. The recycled PET fibers are prepared by sequentially cleaning and activating recycled PET fibers, followed by internal reinforcement modification with nano-silica.

[0032] It should be noted that the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 62℃ for 45 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

[0033] The internal reinforcement of nano-silica includes step ① selecting nano-SiO2 with a particle size of 18-22nm and adding 2% by mass of silane coupling agent KH-550 to a mixer for mixing and stirring to obtain modified nano-SiO2 with surface-grafted amino active groups; step ② feeding the modified nano-SiO2 and cleaned and activated recycled PET fibers into an extruder at a mass ratio of 0.082:1 for melt extrusion, controlling the melt temperature at 270℃ and the stirring speed at 300r / min to obtain nano-SiO2 with a diameter of 0. 0.019-0.021mm composite fiber; Step ③ stretch the composite fiber 3 times, heat set it at 120℃ for 10 minutes to obtain reinforced and shaped fiber; Step ④ place the reinforced and shaped fiber in an environment of -5℃ for 5 minutes to pre-cool, and then feed it into a calendering roller with a wavelength of 0.8mm and a wave height of 0.003mm, and control the feeding speed at 5m / min to obtain a shaped fiber with a regular corrugated surface; and the corrugation depth of the regular corrugated surface is less than or equal to 0.002mm.

[0034] A method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0035] Example 4 A polyester fiber concrete material includes a powder and a liquid component. The powder is composed of cement, fly ash, sand, and recycled PET fibers. The liquid component consists of water and a water-reducing agent. The mass ratio of cement, fly ash, sand, and recycled PET fibers is 300:95:1100:0.8. The recycled PET fibers are prepared by sequentially cleaning and activating recycled PET fibers, followed by surface core-shell structure coating modification.

[0036] It should be noted that the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 58℃ for 35 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

[0037] The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with deionized water at a particle size of 50±5nm and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier. The cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for 20 min; Step ③ Adding nano-C... Add 0.5% by mass of polycarboxylate superplasticizer and deionized water to the aCO3 core-gel shell modifier to obtain a shell-core modifier with a solid content of 30±1%; Step ④ Immerse the cleaned and activated or nano-silica reinforced recycled PET fibers in the shell-core modifier, and obtain coated fibers after ultrasonic treatment; Step ⑤ Place the coated fibers in an environment with a temperature of 80±2℃ for 30 min to dry and obtain continuous coated fibers; Step ⑥ Immerse the continuous coated fibers in a 0.5% by mass KH-550-ethanol solution, control the immersion time to 5 min, and air dry naturally after removal to obtain modified fibers.

[0038] A method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0039] Example 5 A polyester fiber concrete material includes a powder and a liquid component. The powder is composed of cement, fly ash, sand, and recycled PET fibers. The liquid component consists of water and a water-reducing agent. The mass ratio of cement, fly ash, sand, and recycled PET fibers is 300:100:1150:1.2. The recycled PET fibers are prepared by sequentially cleaning and activating recycled PET fibers, followed by surface core-shell structure coating modification.

[0040] It should be noted that the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 58℃ for 35 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

[0041] The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with deionized water at a particle size of 50±5nm and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier. The cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for 20 min; Step ③ Adding nano-C... Add 0.5% by mass of polycarboxylate superplasticizer and deionized water to the aCO3 core-gel shell modifier to obtain a shell-core modifier with a solid content of 30±1%; Step ④ Immerse the cleaned and activated or nano-silica reinforced recycled PET fibers in the shell-core modifier, and obtain coated fibers after ultrasonic treatment; Step ⑤ Place the coated fibers in an environment with a temperature of 80±2℃ for 30 min to dry and obtain continuous coated fibers; Step ⑥ Immerse the continuous coated fibers in a 0.5% by mass KH-550-ethanol solution, control the immersion time to 5 min, and air dry naturally after removal to obtain modified fibers.

[0042] A method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0043] Example 6 A polyester fiber concrete material includes a powder and a liquid component. The powder is composed of cement, fly ash, sand, and recycled PET fibers. The liquid component consists of water and a water-reducing agent. The mass ratio of cement, fly ash, sand, and recycled PET fibers is 300:105:1200:2.2. The recycled PET fibers are prepared by sequentially cleaning and activating recycled PET fibers, followed by surface core-shell structure coating modification.

[0044] It should be noted that the cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 58℃ for 35 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

[0045] The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with deionized water at a particle size of 50±5nm and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier. The cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for 20 min; Step ③ Adding nano-C... Add 0.5% by mass of polycarboxylate superplasticizer and deionized water to the aCO3 core-gel shell modifier to obtain a shell-core modifier with a solid content of 30±1%; Step ④ Immerse the cleaned and activated or nano-silica reinforced recycled PET fibers in the shell-core modifier, and obtain coated fibers after ultrasonic treatment; Step ⑤ Place the coated fibers in an environment with a temperature of 80±2℃ for 30 min to dry and obtain continuous coated fibers; Step ⑥ Immerse the continuous coated fibers in a 0.5% by mass KH-550-ethanol solution, control the immersion time to 5 min, and air dry naturally after removal to obtain modified fibers.

[0046] A method for preparing a polyester fiber concrete material, comprising the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after 28 days of standard curing, the finished polyester fiber concrete material is obtained.

[0047] Example 7 The difference between Example 7 and Example 1 is that in Example 7, the recycled PET fiber is prepared by sequentially cleaning and activating the recycled PET fiber, as well as internal strengthening with nano-silica and surface core-shell structure coating modification.

[0048] The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with deionized water at a particle size of 50±5nm and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier. The cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for 20 min; Step ③ Adding nano-C... Add 0.5% by mass of polycarboxylate superplasticizer and deionized water to the aCO3 core-gel shell modifier to obtain a shell-core modifier with a solid content of 30±1%; Step ④ Immerse the cleaned and activated or nano-silica reinforced recycled PET fibers in the shell-core modifier, and obtain coated fibers after ultrasonic treatment; Step ⑤ Place the coated fibers in an environment with a temperature of 80±2℃ for 30 min to dry and obtain continuous coated fibers; Step ⑥ Immerse the continuous coated fibers in a 0.5% by mass KH-550-ethanol solution, control the immersion time to 5 min, and air dry naturally after removal to obtain modified fibers.

[0049] Example 8 The difference between Example 8 and Example 1 is that in Example 8, the recycled PET fiber is prepared by sequentially cleaning and activating the recycled PET fiber, as well as internal reinforcement with nano-silica and surface core-shell structure coating modification.

[0050] The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with deionized water at a particle size of 50±5nm and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier. The cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for 20 min; Step ③ Adding nano-C... Add 0.5% by mass of polycarboxylate superplasticizer and deionized water to the aCO3 core-gel shell modifier to obtain a shell-core modifier with a solid content of 30±1%; Step ④ Immerse the cleaned and activated or nano-silica reinforced recycled PET fibers in the shell-core modifier, and obtain coated fibers after ultrasonic treatment; Step ⑤ Place the coated fibers in an environment with a temperature of 80±2℃ for 30 min to dry and obtain continuous coated fibers; Step ⑥ Immerse the continuous coated fibers in a 0.5% by mass KH-550-ethanol solution, control the immersion time to 5 min, and air dry naturally after removal to obtain modified fibers.

[0051] Example 9 The difference between Example 9 and Example 1 is that in Example 9, the recycled PET fiber is prepared by sequentially cleaning and activating the recycled PET fiber, as well as internal reinforcement with nano-silica and surface core-shell structure coating modification.

[0052] The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with deionized water at a particle size of 50±5nm and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension, stirring evenly, and then adding 5% by mass of cement slurry, and continuing to stir to obtain a nano-CaCO3 core-gel-shell modifier. The cement slurry is 42.5 grade silicate cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for 20 min; Step ③ Adding nano-C... Add 0.5% by mass of polycarboxylate superplasticizer and deionized water to the aCO3 core-gel shell modifier to obtain a shell-core modifier with a solid content of 30±1%; Step ④ Immerse the cleaned and activated or nano-silica reinforced recycled PET fibers in the shell-core modifier, and obtain coated fibers after ultrasonic treatment; Step ⑤ Place the coated fibers in an environment with a temperature of 80±2℃ for 30 min to dry and obtain continuous coated fibers; Step ⑥ Immerse the continuous coated fibers in a 0.5% by mass KH-550-ethanol solution, control the immersion time to 5 min, and air dry naturally after removal to obtain modified fibers.

[0053] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the recycled PET fibers in Comparative Example 1 were not cleaned and activated, nor were they prepared with internal reinforcement modification of nano-silica.

[0054] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the recycled PET fibers in Comparative Example 2 were not prepared by internal reinforcement modification with nano-silica.

[0055] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that no recycled PET fibers were added in Comparative Example 3.

[0056] Performance testing: According to GB / T 17671-1999: The compressive strength and flexural strength at 28 days were measured, and the splitting tensile strength at the same age was also determined.

[0057] Impact toughness was evaluated using a closed-circuit impact testing machine; The maximum crack width and crack energy release before final fracture were measured.

[0058] The performance test results are shown in Table 1 below.

[0059] Table 1 Performance Test Results

[0060] As shown in Table 1 above, the content of recycled PET fiber in Examples 7 to 9 of this application increased from 0.0535% to 0.1471%, and its flexural strength increased from 7.3 MPa to 7.9 MPa, an increase of 8.2%, its splitting tensile strength increased from 3.2 MPa to 3.4 MPa, an increase of 6.2%, and its ultimate tensile strain increased from 0.110% to 0.125%, an increase of 13.6%. It can be seen that, based on the dual modification method, the increase in the content of recycled PET fiber will increase the spatial network density of recycled PET fiber and have more bridging points when cracks propagate, so as to effectively improve the ultimate tensile strain capacity.

[0061] Based on Comparative Example 1, it can be observed that although the content of recycled PET fiber is increased, the performance is difficult to improve effectively due to the weak interfacial bonding ability. Based on the two different modification schemes in Examples 1 to 6, the synergistic effect of increasing the content of recycled PET fiber is significantly lower than that in Examples 7 to 9. This indicates that synergistic internal reinforcement with nano-silica and surface core-shell structure coating modification will achieve a more significant performance improvement, enabling the prepared polyester fiber concrete material to effectively improve tensile crack resistance and durability.

[0062] In summary, this application provides a polyester fiber concrete material and its preparation method. This polyester fiber concrete material modifies recycled PET fibers through polymer nanocompositing, thereby improving the interfacial bonding effect of the recycled PET fibers in the polyester fiber concrete material and reducing the problem of insufficient stress transfer caused by the reduced cross-sectional area of ​​the recycled PET fibers. This achieves the effect of significantly improving flexural strength while meeting the strength requirements of concrete. Specifically, in the modification treatment of the recycled PET fibers, the cleaning and activation treatment by etching the recycled PET fibers with NaOH solution forms a micro-concave structure on the surface of the recycled PET fibers, thereby increasing the specific surface area. Combined with the internal reinforcement of nano-silica, this makes the structure of the recycled PET fibers more compact and effectively increases the number of physical interlocking points. The surface core-shell structure coating, based on a nano-CaCO3 core-gel-shell modifier, forms a core-shell structure, improving the fusion effect between the surface of the recycled PET fibers and the powder, significantly reducing interfacial defects between the recycled PET fibers and the powder, thereby improving the structural strength of the polyester fiber concrete material. Meanwhile, the strength of recycled PET fibers is significantly improved and the interfacial bonding is effectively improved through nano-silica reinforcement and stretching. This enables the recycled PET fibers to effectively transfer stress and inhibit crack propagation in the polyester fiber concrete material. When the polyester fiber concrete material is subjected to external forces, the recycled PET fibers achieve an effective bridging effect, reducing the generation and development of cracks. This effectively improves the compressive, tensile, and impact toughness of the polyester fiber concrete material and reduces the risk of brittle fracture. Therefore, the preparation method of the polyester fiber concrete material is convenient, and by turning waste PET material into recycled PET fiber and applying it to the polyester fiber concrete material, it not only effectively solves the environmental protection problem of waste PET material and realizes resource recycling, but also overcomes the problems of poor compatibility and limited reinforcing effect between recycled PET fiber and the powder of the polyester fiber concrete material through effective modification treatment, so that recycled PET fiber can effectively improve the mechanical and chemical properties of the polyester fiber concrete material.

[0063] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.

[0064] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0065] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A polyester fiber reinforced concrete material, characterized in that, include: The powder is composed of a mixture of cement, fly ash, sand, gravel, and recycled PET fibers. Water-based materials consist of water and water-reducing agents or water; The mixing mass ratio of the cement, fly ash, sand and gravel and recycled PET fiber is 300:95-105:1100-1200:0.8-2.

2. The recycled PET fiber is prepared by sequentially cleaning and activating recycled PET fiber, followed by internal reinforcement with nano-silica and / or surface core-shell structure coating modification.

2. The polyester fiber reinforced concrete material according to claim 1, characterized in that: The cement is grade 42.5 high-strength silicate cement.

3. The polyester fiber reinforced concrete material according to claim 1, characterized in that: The sand and gravel consist of gravel with a particle size of 5-15mm and medium sand.

4. The polyester fiber concrete material according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

5. The polyester fiber concrete material according to claim 1, characterized in that: The cleaning and activation process includes: Step ① Selecting recycled PET fibers with a length of 12-15 mm and a diameter of 0.015-0.023 mm for later use; Step ② Immersing the recycled PET fibers in a 5% NaOH solution and stirring in a constant temperature water bath at 58-62℃ for 35-45 minutes to obtain etched fibers with a surface etching depth ≤0.002 mm; Step ③ Rinsing the etched fibers with deionized water until the pH is less than 7.2, then soaking them in a 3% dilute hydrochloric acid solution for 5 minutes, followed by washing with deionized water and drying at 60℃ to obtain clean and activated fibers.

6. The polyester fiber concrete material according to claim 1, characterized in that: The internal reinforcement of the nano-silica includes the following steps: Step ① Selecting nano-SiO2 with a particle size of 18-22nm and adding 2% by mass of silane coupling agent KH-550 to a mixer for mixing and stirring to obtain modified nano-SiO2 with surface-grafted amino active groups; Step ② Adding the modified nano-SiO2 and cleaned and activated recycled PET fibers to an extruder for melt extrusion at a mass ratio of 0.076-0.082:1, controlling the melt temperature at 270℃ and the stirring speed at 300r / min to obtain composite fibers with a diameter of 0.019-0.021mm; Step ③ Stretching the composite fibers three times and heat-setting them at 120℃ for 10min to obtain reinforced and shaped fibers.

7. The polyester fiber concrete material according to claim 6, characterized in that: The method also includes pre-cooling the reinforced and shaped fiber in an environment with a temperature of -5℃ for 5 minutes, and then feeding it into a calendering roller with a wavelength of 0.8 mm and a wave height of 0.003 mm on the surface, controlling the feeding speed to be 5 m / min, to obtain a shaped fiber with a regular corrugated surface; and the corrugation depth of the regular corrugated surface is less than or equal to 0.002 mm.

8. The polyester fiber reinforced concrete material according to claim 1, characterized in that: The surface core-shell structure coating modification includes the following steps: Step ① Mixing nano-CaCO3 with a particle size of 50±5nm with deionized water and dispersing it ultrasonically to obtain a nano-CaCO3 suspension with a solid-liquid ratio of 1:5; Step ② Adding 10% by mass of silane coupling agent to the nano-CaCO3 suspension and stirring until homogeneous, then adding 5% by mass of cement slurry and stirring continuously to obtain a nano-CaCO3 core-gel-shell modifier; Step ③ Adding 0.5% by mass of water-reducing agent and deionized water to the nano-CaCO3 core-gel-shell modifier to obtain a core-shell modifier with a solid content of 30±1%; Step ④ Immersing cleaned and activated or nano-silica-reinforced recycled PET fibers into the core-shell modifier and ultrasonically treating them to obtain coated fibers; Step ⑤ Drying the coated fibers in an environment at 80±2℃ for 30 minutes to obtain continuous coated fibers. Step 6: Immerse the continuously coated fiber in a 0.5% KH-550-ethanol solution for 5 minutes, and then air dry it after removal to obtain the modified fiber.

9. A polyester fiber reinforced concrete material according to claim 8, characterized in that: In step ②, the cement slurry is 42.5 grade Portland cement with a water-cement ratio of 0.4, and the stirring speed is controlled at 800 r / min for a continuous stirring time of 20 min; in step ③, the water-reducing agent is a polycarboxylate superplasticizer.

10. A method for preparing a polyester fiber reinforced concrete material, used to prepare a polyester fiber reinforced concrete material as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1, Aggregate premixing: Put cement, fly ash, sand and gravel into a mixing mixer and dry mix to obtain uniformly dispersed aggregate; Step 2, Fiber filling: Add the recycled PET fibers into the mixer in multiple batches and mix them evenly, controlling the mixing speed to 100 r / min to obtain fiber aggregate; Step 3, Add water and stir: Add water alone to the fiber aggregate, or add water-reducing agent and water, and stir to obtain fiber aggregate slurry; Step 4, Pouring and Curing: The fiber aggregate slurry is poured and compacted using a steel mold, and after standard curing for 28 days, the finished polyester fiber concrete material is obtained.

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