A high-performance powder material based on polymer fiber-reinforced UHPC and a preparation method thereof

Abstract

The application discloses a kind of high-performance powder materials based on high polymer fiber reinforced UHPC and preparation method thereof, belong to concrete technical field.Preparation method includes: plasma surface activation treatment is carried out to PE fiber, and oxygen-containing active group is introduced;Amino-terminated polyether is grafted to the surface of fiber, and forms flexible molecular brush layer;Grafting fiber is immersed in mineralization solution containing calcium ions, and in situ growth calcium carbonate and other mineral seed crystals on the surface of molecular brush layer;Modified fiber is mixed with cementitious material, aggregate and other components to prepare UHPC;The gradient interface structure of "PE fiber-flexible layer-mineral layer-matrix" constructed by the application realizes the synergy of high strength and high toughness by realizing strong bonding through chemical bonding, relieving modulus mismatch through flexible layer, and enhancing friction by mineral interlocking.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a high-performance UHPC powder material based on polymer fiber reinforcement and its preparation method. Background Technology

[0002] Ultra-High Performance Concrete (UHPC) is a novel cementitious material with ultra-high compressive strength, excellent durability, and a dense microstructure. Through precise particle size distribution design, ultra-low water-cement ratio, and the incorporation of highly efficient water-reducing agents, UHPC achieves extreme density and is widely used in fields with extremely stringent material performance requirements, such as bridge engineering, nuclear power plant protection structures, and marine engineering.

[0003] However, the high strength of UHPC comes at the cost of toughness. Due to its ultra-low water-cement ratio and dense structure, UHPC exhibits significant brittle fracture characteristics, low tensile strength, and insufficient post-cracking load-bearing capacity, which greatly limits its application under dynamic loads, impact loads, or large deformation conditions. To improve the toughness and crack resistance of UHPC, the engineering community has widely adopted the technical approach of incorporating high-performance fibers.

[0004] Currently, commonly used reinforcing fibers in UHPC mainly include steel fibers, carbon fibers, basalt fibers, and polymer fibers. Among them, steel fibers have become the mainstream choice for fiber reinforcement in UHPC due to their high elastic modulus (approximately 200 GPa) and good bonding performance with the cement matrix. A typical steel fiber reinforced UHPC, with a 2% volumetric admixture, can achieve a flexural strength of [missing value]. It exhibits excellent bending resistance.

[0005] However, steel fiber reinforced UHPC also has many limitations: (1) The steel fiber density is high (approximately 7.8 g / cm³). 3 (1) The structure's self-weight is significantly increased; (2) Steel fibers are at risk of corrosion in a strongly alkaline environment, affecting long-term durability; (3) The high stiffness of steel fibers causes the composite material to fail rapidly after reaching peak strength, with limited improvement in toughness; (4) The high cost of steel fibers increases the economic burden of UHPC.

[0006] In contrast, polymer fibers, especially high-strength, high-modulus polyethylene fibers (PE fibers), have a low density (approximately 0.97 g / cm³). 3 It boasts advantages such as corrosion resistance and high ductility. The tensile strength of PE fiber can reach [value missing]. Elongation at break is as high as In theory, it can provide excellent toughening effects for UHPC. In addition, PE fibers are non-conductive and non-magnetic, which has irreplaceable advantages in certain special applications (such as electromagnetic shielding requirements).

[0007] However, the application of PE fibers in cement-based composites faces serious technical bottlenecks: First, the poor interfacial adhesion is the most fundamental problem. PE fibers have a smooth surface, strong chemical inertness, and low surface energy, meaning they bond with the cement matrix primarily through weak mechanical friction. Studies have shown that the interfacial shear strength between smooth PE fibers and the cement matrix is ​​typically only... Far lower than steel fiber The weak interface causes the fibers to slip easily when the composite material is under stress, making it impossible to effectively transfer stress and significantly reducing the reinforcing effect.

[0008] Secondly, fiber dispersion is also a significant issue. PE fibers have a highly hydrophobic surface, making them prone to agglomeration and entanglement in cement paste, forming "fiber balls." This not only affects the fluidity of the paste but also creates weak areas after hardening, becoming the initiation points for cracks.

[0009] To address the aforementioned technical challenges, existing technologies have proposed various methods for modifying the surface of PE fibers: Physical modification methods mainly include plasma treatment and corona discharge treatment, which introduce oxygen-containing functional groups onto the fiber surface by bombarding it with high-energy particles, thereby improving surface activity. However, the effects of physical modification are usually relatively superficial, the modified layer thickness is limited, and its stability is insufficient in alkaline environments.

[0010] Chemical modification methods include acid etching, silane coupling agent treatment, and graft polymerization. Among these, silane coupling agent treatment is a relatively mature technology that can improve the compatibility between fibers and the matrix to a certain extent. However, most existing chemical modification methods only focus on improving chemical bonding strength, neglecting the modulus matching problem between PE fibers (soft) and cement matrix (hard). Although direct chemical bonding improves the initial bond strength, the lack of a transition layer makes it prone to interfacial brittle cracking under stress.

[0011] In summary, how to effectively solve the interfacial bonding and dispersion problems between PE fibers and the UHPC matrix while maintaining the advantages of PE fibers being lightweight and corrosion-resistant, and how to construct a PE fiber-reinforced UHPC material system that has both high strength and high toughness, is a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0012] To overcome the technical problems of strong surface inertness of PE fibers, weak adhesion to the matrix, and easy entrainment of air bubbles during stirring in existing UHPC materials, which leads to interface defects, this invention provides a high-performance UHPC powder material based on polymer fiber reinforcement and its preparation method.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: A high-performance UHPC powder material based on polymer fiber reinforcement is made from the following components in parts by weight: cementing material Portions; aggregates Parts; chemical admixtures Parts; and surface-functionalized modified PE fibers share.

[0014] The surface-functionalized modified PE fiber has a core-shell structure, including a PE fiber matrix and a flexible mineralization induction layer anchored to the surface of the PE fiber matrix by chemical bonding; the flexible mineralization induction layer is composed of amino-terminated polyether molecular chains and calcium-containing mineral seeds grown in situ on the molecular chains.

[0015] The cementitious material includes silicate cement, silica fume, and ultrafine mineral powder; the aggregate is quartz sand; and the chemical admixture is powdered polycarboxylate superplasticizer.

[0016] To ensure that the UHPC matrix possesses superior mechanical properties and dry-mix storage stability, the present invention provides the following preferred specifications for the aforementioned cementitious materials, aggregates, and chemical admixtures: Silicate cement: P.II 52.5 grade or higher silicate cement is preferred, with a specific surface area of C3A (tricalcium aluminate) content High-grade, low-C3A cement is selected to reduce the heat of hydration and ensure high early strength of the matrix.

[0017] Silica fume: Preferably, non-dense microsilica powder with a SiO2 content of [missing information]. The average particle size is This fills the tiny gaps between cement particles, creating a volcanic ash effect.

[0018] Ultrafine mineral powder: S95 or S105 grade granulated blast furnace slag powder is preferred, with a specific surface area of It is used to improve the bulk density of powder and the development of its strength in the later stage.

[0019] Specifically, in the In the cementitious materials, the mass ratio of silicate cement, silica fume, and ultrafine mineral powder is as follows: : : .

[0020] The aggregate is multi-graded quartz sand with a SiO2 content of mud content .

[0021] To comply with the principle of maximum bulk density, the quartz sand is composed of coarse sand ( mesh), medium sand ( (mesh) and fine sand ( (Item) by mass ratio : It is a compound of 1.0. This continuous gradation design can minimize the porosity of the matrix.

[0022] Since the product of this invention is in the form of a dry-mixed powder, the polycarboxylate superplasticizer must be a powdered, high-water-reducing polycarboxylate superplasticizer with a high solid content. Water reduction rate .

[0023] In addition, the chemical additives may also contain premixed powdered defoamers (such as organosilicon powder defoamers) as needed to further reduce the gas content during the stirring process.

[0024] The surface-functionalized modified PE fiber is prepared by the following steps: Step S1: Surface pre-activation treatment PE fiber precursors are surface activated to generate oxygen-containing active groups on their surface, resulting in pre-activated PE fibers.

[0025] As a preferred technical solution, the surface activation treatment employs low-temperature plasma treatment. The specific process involves placing the PE fiber in a plasma treatment device, with the treatment atmosphere being argon, oxygen, or nitrogen, and the treatment power being [missing information]. Processing time is .

[0026] The diameter of the PE fiber precursor is , length is Tensile strength elastic modulus .

[0027] Principle explanation: High-energy particles bombard the PE molecular chain, breaking CH or CC bonds to generate free radicals, which react with the surrounding gases to generate a large number of oxygen-containing active groups such as carboxyl (-COOH), hydroxyl (-OH) and carbonyl (C=O) in situ on the fiber surface, providing reaction sites for subsequent chemical grafting.

[0028] Step S2: Grafting flexible polyetheramine molecular brush The pre-activated PE fibers obtained in step S1 are immersed in a reaction solution containing terminal amino polyethers for grafting reaction. The amino groups at the ends of the terminal amino polyether molecular chains are chemically bonded to the oxygen-containing active groups to form a flexible molecular brush layer on the fiber surface, thus obtaining grafted PE fibers.

[0029] Raw material selection: The terminal amino polyether is a polyetheramine with copolymer segments of ethylene oxide (EO) and propylene oxide (PO); its weight-average molecular weight is [missing information]. ; and the molar percentage of propylene oxide (PO) in the copolymer segment is .

[0030] Reaction conditions: The reaction solvent is ethanol or water, and the ratio of the pre-activated PE fiber to the reaction solvent is 1:1. The concentration of the amino-terminated polyether in the reaction solvent is The reaction temperature is The reaction time is .

[0031] Activation Enhancement: To promote grafting efficiency, an amidating condensation agent is added during the reaction. The amidating condensation agent consists of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) and N-hydroxysuccinimide (NHS). To ensure sufficient activation of trace carboxyl groups on the fiber surface, the concentration of the amidating condensation agent in the reaction solution is set as follows: the concentration of EDC·HCl is... The concentration of NHS is .

[0032] Preferably, the mass ratio of EDC·HCl to NHS is controlled at 1: 1. This excessive concentration of activator is much higher than the stoichiometry of carboxyl groups on the fiber surface, which can overcome the steric hindrance effect of the solid-liquid interface reaction and maximize the grafting rate.

[0033] Reaction Mechanism: The primary amine at the end of the amino-terminated polyether acts as a nucleophile, attacking the activated carboxyl group and undergoing a dehydration condensation reaction to form a stable amide covalent bond. After the reaction, ungrafted free polyether amine is removed by washing to ensure that the flexible molecular brush layer is firmly anchored to the fiber surface by chemical bonds.

[0034] Step S3: In-situ mineralization synergy Grafted PE fibers are immersed in a mineralization precursor solution, and calcium ions are chelated using the active sites on the flexible molecular brush layer to induce the growth of calcium-containing mineral seeds in situ. The result is obtained after drying.

[0035] Mineralization system: The mineralization precursor solution is a saturated calcium hydroxide solution or a buffer solution containing calcium salts (such as calcium nitrate, calcium chloride, or calcium acetate), and the concentration of calcium ions in the solution is [missing information]. pH value maintained The ratio of grafted PE fiber to mineralized precursor solution is 1: .

[0036] Synergistic process: The immersion time of the fiber in the solution is During this period, the terminal amino polyether molecular chain is in an extended conformation. The ether bonds (-O-) on the molecular chain and the terminal amino groups strongly chelate calcium ions in the solution through coordination, forming a calcium-rich precursor layer.

[0037] Curing and shaping: After soaking, the fibers need to undergo... Hot air drying. The drying process causes the adsorption layer to dehydrate and shrink, which tightly encapsulates and fixes the in-situ grown micro / nano-sized calcium-containing mineral seeds onto the polyether flexible layer, forming a shear-resistant "soft-hard composite" shell.

[0038] This invention also claims a method for preparing a UHPC high-performance powder material, comprising the following steps: (1) The cementitious material, aggregate and chemical admixture are put into a mixer and dry-mixed to obtain a premix; (2) The prepared surface-functionalized modified PE fibers are added to the premix by airflow dispersion or batch feeding; (3) Continue stirring until the fibers are evenly dispersed in the powder, then discharge and package.

[0039] To ensure that the fibers do not agglomerate and that the flexible mineralization-inducing layer on the surface does not detach due to excessive friction, the stirring in step (3) is performed using a forced planetary mixer or a plow mixer, with the stirring speed controlled at [speed value missing]. The stirring time is .

[0040] Compared with the prior art, the present invention has the following beneficial effects: 1. The UHPC high-performance powder material provided by this invention achieves a dual breakthrough in mechanical and workability through the scientific compounding of its components. Specifically, the cementitious material system (cement, silica fume, and ultrafine mineral powder) constructs a dense microstructure, providing ultra-high matrix strength; the rationally graded quartz sand aggregate further optimizes the particle packing density; and the introduction of surface-functionalized modified PE fibers, a core component, solves the interfacial bonding problem between high-strength fibers and the cement matrix in traditional UHPC. During mixing and subsequent hydration, these modified fibers not only exhibit excellent dispersibility, avoiding stress concentration defects caused by fiber agglomeration, but also actively induce hydration products (CSH gel) in the matrix to grow directionally onto the fiber surface, forming a strong and tough interface with both chemical bonding and physical interlocking. This "soft-hard" interfacial structure significantly improves the fiber pull-out work, enabling the UHPC material to withstand higher loads after cracking under stress through the bridging effect of the fibers, significantly improving the material's flexural strength, ductility, and energy absorption capacity.

[0041] 2. The fiber preparation process of this invention improves the fiber surface properties progressively through a three-step synergistic strategy of "surface activation - flexible grafting - in-situ mineralization": First, the surface activation treatment breaks the chemical inertness of the PE fiber surface, and the in-situ generated carboxyl groups and other oxygen-containing groups provide highly active "chemical anchors" for subsequent modification, which is a prerequisite for achieving strong chemical bonding; Second, the grafting of flexible polyetheramine molecular brushes plays a dual role: On the one hand, the flexible segments are firmly anchored to the fiber surface through stable amide covalent bonds, making them shear-resistant and non-detachable; on the other hand, the hydrophobic propylene oxide (PO) segments introduced into the polyether chain endow the fiber with... The fiber surface exhibits excellent in-situ defoaming capabilities, actively eliminating microbubbles adhering to the fiber surface during stirring and significantly reducing interfacial porosity. Simultaneously, the flexible chain segments can also serve as a "stress buffer layer," improving the modulus matching between the rigid matrix and the fiber. Finally, in-situ mineralization synergistically utilizes the chelating effect of polyether chains on calcium ions to construct a nanoscale calcium-containing mineral seed layer on the outermost layer of the fiber. This not only protects the internal flexible layer but, more importantly, possesses a natural crystal structure similarity to cement hydration products, inducing rapid nucleation and growth of cement slurry on the fiber surface. This achieves molecular-level chemical welding, significantly improving fiber pull-out resistance. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0043] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0044] A method for preparing UHPC high-performance powder material based on polymer fiber reinforcement includes the following steps. (1) Place the PE fiber in a plasma processing device. The processing atmosphere is argon, oxygen, or nitrogen, and the processing power is [missing information]. Processing time is Preactivated PE fibers are obtained; (2) The pre-activated PE fiber is immersed in a reaction solution containing terminal amino polyether for grafting reaction (the terminal amino polyether is a polyetheramine with copolymer segments of ethylene oxide (EO) and propylene oxide (PO) and its weight average molecular weight is ). And the molar percentage of propylene oxide (PO) in the copolymer segment is The reaction solvent is ethanol or water, and the ratio of the pre-activated PE fiber to the reaction solvent is 1: The concentration of the amino-terminated polyether in the reaction solvent is The reaction temperature is The reaction time is An amidation condensing agent (EDC / NHS system) is added during the reaction, and the concentration of EDC·HCl is [missing information]. The concentration of NHS is Grafted PE fibers were obtained. (3) The grafted PE fibers are immersed in a mineralization precursor solution, wherein the mineralization precursor solution is a saturated calcium hydroxide solution or a buffer solution containing calcium salts (such as calcium nitrate, calcium chloride, or calcium acetate), and the concentration of calcium ions in the solution is [missing information]. pH value maintained The ratio of grafted fiber to mineralized precursor solution is 1: The immersion time of the fiber in the solution is After soaking, the fibers need to be processed. Hot air drying yields surface-functionalized modified PE fibers; (4) Partial cementitious materials (silicate cement, silica fume and ultrafine mineral powder in mass ratio) : : (Combined) aggregate ( mesh coarse sand, Eye Sand and Fine sand by mass ratio : (1.0 compound) and A portion of the chemical admixture polycarboxylate superplasticizer is added to a mixer and dry-mixed to obtain a premix; (5) Surface-functionalized modified PE fibers are added to the premix by airflow dispersion or batch feeding; (6) Use a forced planetary mixer or a plow mixer, and control the mixing speed to be as follows: The stirring time is Continue this process until the fibers are evenly dispersed in the powder, then discharge and package.

[0045] The present invention will be further described below through specific embodiments. Example 1

[0046] A method for preparing UHPC high-performance powder material based on polymer fiber reinforcement includes the following steps. (1) The diameter is PE fibers with a length of 12mm were placed in a plasma treatment device. The treatment atmosphere was argon, the treatment power was 500W, and the treatment time was 30s to obtain pre-activated PE fibers. (2) The pre-activated PE fiber was immersed in a reaction solution containing terminal amino polyether (Jeffamine M-2070) for grafting reaction. The reaction solvent was ethanol, the ratio of pre-activated PE fiber to reaction solvent was 1:50 g / mL, and the concentration of terminal amino polyether in the reaction solvent was 50 g / L. During the reaction, an amidation condensing agent (EDC / NHS system) was added. The concentration of EDC·HCl was 5 g / L, and the concentration of NHS was 5 g / L. The reaction temperature was 80℃, and the reaction time was 2 h to obtain grafted PE fiber. (3) The grafted PE fiber was immersed in a Tris-HCl buffer solution of calcium chloride (calcium ion concentration was 0.5 mol / L, pH=10); the ratio of grafted PE fiber to mineralized precursor solution was 1:100 g / mL; the fiber was immersed in the solution for 12 h; after immersion, the fiber was dried by hot air at 55℃ to obtain surface functionalized modified PE fiber. (4) Mix 12000g of cementitious material (a mixture of silicate cement, silica fume, and ultrafine mineral powder in a mass ratio of 0.75:0.12:0.15) and 14000g of aggregate ( mesh coarse sand, Eye Sand and Fine sand (mixed in a mass ratio of 1.2:1.7:1.0) and 500g of polycarboxylate superplasticizer are added to a mixer and dry-mixed to obtain a premix. (5) Add 400g of surface-functionalized modified PE fiber to the premix in batches; (6) Use a forced planetary mixer, control the mixing speed at 100 r / min, and the mixing time at 3 min until the fiber is evenly dispersed in the powder. Then discharge and package the product. Example 2

[0047] A method for preparing UHPC high-performance powder material based on polymer fiber reinforcement includes the following steps. (1) The diameter is PE fibers with a length of 12mm were placed in a plasma treatment device. The treatment atmosphere was argon, the treatment power was 400W, and the treatment time was 80s to obtain pre-activated PE fibers. (2) The pre-activated PE fiber was immersed in a reaction solution containing terminal amino polyether (Jeffamine M-2070) for grafting reaction. The reaction solvent was ethanol, the ratio of pre-activated PE fiber to reaction solvent was 1:40 g / mL, and the concentration of terminal amino polyether in the reaction solvent was 40 g / L. During the reaction, an amidation condensing agent (EDC / NHS system) was added. The concentration of EDC·HCl was 4 g / L, and the concentration of NHS was 4 g / L. The reaction temperature was 70℃, and the reaction time was 3 h to obtain grafted PE fiber. (3) The grafted PE fiber was immersed in a Tris-HCl buffer solution of calcium chloride (calcium ion concentration was 0.4 mol / L, pH=10); the ratio of grafted PE fiber to mineralized precursor solution was 1:80 g / mL; the fiber was immersed in the solution for 9 hours. After immersion, the fiber was dried by hot air at 55℃ to obtain surface functionalized modified PE fiber. (4) Mix 11,000g of cementitious material (a mixture of silicate cement, silica fume, and ultrafine mineral powder in a mass ratio of 0.75:0.12:0.15) and 13,000g of aggregate ( mesh coarse sand, Eye Sand and Fine sand (mixed in a mass ratio of 1.2:1.7:1.0) and 400g of polycarboxylate superplasticizer are added to a mixer and dry-mixed to obtain a premix. (5) Add 300g of surface-functionalized modified PE fiber to the premix in batches; (6) Use a forced planetary mixer, control the mixing speed at 80 r / min, and the mixing time at 5 min until the fiber is evenly dispersed in the powder. Then discharge and package the product. Example 3

[0048] A method for preparing UHPC high-performance powder material based on polymer fiber reinforcement includes the following steps. (1) The diameter is PE fibers with a length of 12mm were placed in a plasma treatment device. The treatment atmosphere was argon, the treatment power was 200W, and the treatment time was 130s to obtain pre-activated PE fibers. (2) The pre-activated PE fiber was immersed in a reaction solution containing terminal amino polyether (Jeffamine M-2070) for grafting reaction. The reaction solvent was ethanol, the ratio of pre-activated PE fiber to reaction solvent was 1:30 g / mL, and the concentration of terminal amino polyether in the reaction solvent was 20 g / L. During the reaction, an amidation condensing agent (EDC / NHS system) was added. The concentration of EDC·HCl was 2 g / L, and the concentration of NHS was 2 g / L. The reaction temperature was 50℃, and the reaction time was 5 h to obtain grafted PE fiber. (3) The grafted PE fiber was immersed in a Tris-HCl buffer solution of calcium chloride (calcium ion concentration was 0.1 mol / L, pH=10); the ratio of grafted PE fiber to mineralized precursor solution was 1:40 g / mL; the fiber was immersed in the solution for 4 hours. After immersion, the fiber was dried by hot air at 55℃ to obtain surface functionalized modified PE fiber. (4) Mix 9000g of cementitious material (a mixture of silicate cement, silica fume, and ultrafine mineral powder in a mass ratio of 0.75:0.12:0.15) and 11000g of aggregate ( mesh coarse sand, Eye Sand and Fine sand (mixed in a mass ratio of 1.2:1.7:1.0) and 300g of polycarboxylate superplasticizer are added to a mixer and dry-mixed to obtain a premix. (5) Add 200g of surface-functionalized modified PE fiber to the premix in batches; (6) Use a forced planetary mixer, control the mixing speed at 80 r / min, and the mixing time at 8 min until the fiber is evenly dispersed in the powder. Then, discharge and package the product. Example 4

[0049] A method for preparing UHPC high-performance powder material based on polymer fiber reinforcement includes the following steps. (1) The diameter is PE fibers with a length of 12mm were placed in a plasma treatment device. The treatment atmosphere was argon, the treatment power was 100W, and the treatment time was 180s to obtain pre-activated PE fibers. (2) The pre-activated PE fiber was immersed in a reaction solution containing terminal amino polyether (Jeffamine M-2070) for grafting reaction. The reaction solvent was ethanol, the ratio of pre-activated PE fiber to reaction solvent was 1:50 g / mL, and the concentration of terminal amino polyether in the reaction solvent was 10 g / L. During the reaction, an amidation condensing agent (EDC / NHS system) was added. The concentration of EDC·HCl was 1 g / L, and the concentration of NHS was 1 g / L. The reaction temperature was 40℃, and the reaction time was 6 h to obtain grafted PE fiber. (3) The grafted PE fiber was immersed in a Tris-HCl buffer solution of calcium chloride (calcium ion concentration was 0.05 mol / L, pH=10); the ratio of grafted PE fiber to mineralized precursor solution was 1:20 g / mL; the fiber was immersed in the solution for 1 h; after immersion, the fiber was dried by hot air at 55℃ to obtain surface functionalized modified PE fiber. (4) Mix 8000g of cementitious material (a mixture of silicate cement, silica fume, and ultrafine mineral powder in a mass ratio of 0.75:0.12:0.15) and 10000g of aggregate ( mesh coarse sand, Eye Sand and Fine sand (mixed in a mass ratio of 1.2:1.7:1.0) and 200g of polycarboxylate superplasticizer are added to a mixer and dry-mixed to obtain a premix. (5) Add 150g of surface-functionalized modified PE fiber to the premix in batches; (6) Use a forced planetary mixer, control the mixing speed at 30 r / min, and the mixing time at 10 min until the fiber is evenly dispersed in the powder. Then discharge and package the product.

[0050] Comparative Example 1 A method for preparing UHPC high-performance powder material based on polymer fiber reinforcement includes the following steps: (1) The diameter is PE fibers with a length of 12mm were placed in a plasma treatment device. The treatment atmosphere was argon, the treatment power was 500W, and the treatment time was 30s to obtain pre-activated PE fibers. (2) The pre-activated PE fiber was immersed in a reaction solution containing terminal amino polyether (Jeffamine M-2070) for grafting reaction. The reaction solvent was ethanol, the ratio of pre-activated PE fiber to reaction solvent was 1:50 g / mL, and the concentration of terminal amino polyether in the reaction solvent was 50 g / L. During the reaction, an amidation condensing agent (EDC / NHS system) was added. The concentration of EDC·HCl was 5 g / L, and the concentration of NHS was 5 g / L. The reaction temperature was 80℃, and the reaction time was 2 h to obtain grafted PE fiber. (3) Mix 12000g of cementitious material (a mixture of silicate cement, silica fume, and ultrafine mineral powder in a mass ratio of 0.75:0.12:0.15) and 14000g of aggregate ( mesh coarse sand, Eye Sand and Fine sand (mixed in a mass ratio of 1.2:1.7:1.0) and 500g of polycarboxylate superplasticizer are added to a mixer and dry-mixed to obtain a premix. (4) Add 400g of grafted PE fiber and 20g of calcium carbonate powder to the premix in batches; (5) Use a forced planetary mixer, control the mixing speed at 100 r / min, and the mixing time at 3 min until the fiber is evenly dispersed in the powder. Then, discharge and package the product.

[0051] Comparative Example 2 A method for preparing UHPC high-performance powder material based on polymer fiber reinforcement includes the following steps. (1) The diameter is PE fibers with a length of 12mm were placed in a plasma treatment device. The treatment atmosphere was argon, the treatment power was 500W, and the treatment time was 30s to obtain pre-activated PE fibers. (2) The pre-activated PE fiber was immersed in a Tris-HCl buffer solution of calcium chloride (calcium ion concentration was 0.5 mol / L, pH=10); the ratio of grafted PE fiber to mineralized precursor solution was 1:100 g / mL; the fiber was immersed in the solution for 12 h; after immersion, the fiber was dried by hot air at 55℃ to obtain surface functionalized modified PE fiber. (3) Mix 12000g of cementitious material (a mixture of silicate cement, silica fume, and ultrafine mineral powder in a mass ratio of 0.75:0.12:0.15) and 14000g of aggregate ( mesh coarse sand, Eye Sand and Fine sand (mixed in a mass ratio of 1.2:1.7:1.0) and 500g of polycarboxylate superplasticizer are added to a mixer and dry-mixed to obtain a premix. (4) Add 400g of surface-functionalized modified PE fiber and 10g of amino-terminated polyether (Jeffamine M-2070) to the premix in batches; (5) Use a forced planetary mixer, control the mixing speed at 100 r / min, and the mixing time at 3 min until the fiber is evenly dispersed in the powder. Then, discharge and package the product.

[0052] To verify the performance of the UHPC high-performance powder material prepared in this invention, tests were conducted according to GB / T 31387-2015 "Reactive Powder Concrete" and related standards: Flowability (spreadability): The flowability of freshly mixed mortar was tested according to GB / T 2419-2005 "Method for Determination of Flowability of Cement Mortar" to characterize the dispersibility of fibers and their influence on rheology.

[0053] Flexural and compressive strengths: The grout was cast into prism-shaped specimens of 40mm × 40mm × 160mm. After standard curing for 28 days, the strengths were measured using a fully automated flexural and compressive strength testing machine. The failure mode description was obtained through macroscopic observation of the failed prism-shaped specimens during the flexural strength and fracture energy tests.

[0054] Interfacial shear strength: A single fiber was vertically fixed at the center of the mold, and the matrix material was poured, with the fiber embedment depth controlled at 5 mm. After standard curing for 28 days, the specimen was subjected to a pull-out test using a computer-controlled electronic universal testing machine at a loading rate of 1 mm / min. The maximum load Fmax during fiber pull-out was recorded, and the result was calculated according to the formula... The interfacial shear strength was calculated (where d is the fiber diameter and L is the embedment depth).

[0055] Fracture energy: The fracture energy is calculated by recording the load-deflection curve through a three-point bending beam test, which is used to evaluate the toughness of the material.

[0056] Table 1 UHPC Performance Test Results Note: "Multiple cracks" indicates that the fiber and the matrix have formed an excellent stress transfer mechanism, which dissipates energy; "brittle fracture" indicates that the interfacial bonding is insufficient and the fiber has failed to effectively inhibit crack propagation.

[0057] With adjustments to plasma treatment intensity, grafting concentration, and mineralization time (examples) The material properties exhibit regular changes, but all remain at a high level, indicating that the preparation process of this invention has good controllability and adaptability. The combination of process parameters in Example 1 achieved the optimal performance balance.

[0058] Example 1 exhibits a flexural strength as high as 26.8 MPa and a fracture energy of 3650 N / m, significantly superior to the comparative example. This indicates that the gradient interface structure of "PE fiber-flexible polyetheramine layer-mineral seed crystal-cement matrix" constructed in this invention not only provides extremely strong chemical and physical anchoring forces but also significantly enhances the toughness of the material through the buffering effect of the flexible layer.

[0059] In Comparative Example 1, although grafted fibers and calcium salts were used, the interfacial shear strength of a single fiber was only 2.1 MPa, far lower than the 6.8 MPa in Example 1. This indicates that simple physical mixing cannot form an effective mineral interlocking structure on the fiber surface. Free calcium salts cannot provide interfacial friction; instead, they may affect cement hydration due to excessively high local ion concentrations, leading to a slight decrease in overall strength.

[0060] Comparative Example 2 used direct mineralized fibers without a flexible layer and added polyetheramine. The added polyetheramine easily caused flocculation or uneven air entrainment in strongly alkaline cement paste, resulting in a decrease in flowability from 245 mm to 210 mm. Although the fiber surface contained minerals, the lack of a flexible polyetheramine molecular brush as a buffer layer led to a modulus mismatch between the rigid mineral layer and the soft PE fiber. During stress, the mineral shell easily detached brittlely from the fiber surface, resulting in low interfacial shear strength (3.2 MPa) and extremely low fracture energy (2260 N / m). This fully demonstrates that introducing terminal amino polyethers to form a chemically bonded flexible molecular brush layer in step S2 is the key technical means to solve the contradiction between high strength and high toughness, rather than simply adding components.

[0061] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-performance UHPC powder material based on polymer fiber reinforcement, characterized in that, It is made from the following components in parts by weight: cementing material Portions; aggregates Parts; chemical admixtures share; and surface-functionalized modified PE fibers share.

2. The UHPC high-performance powder material according to claim 1, characterized in that, The surface-functionalized modified PE fiber is prepared by the following steps: Step S1: Surface activation treatment is performed on the PE fiber filament to generate oxygen-containing active groups on its surface, thus obtaining pre-activated PE fiber; Step S2: Immerse the pre-activated PE fiber in a reaction solution containing terminal amino polyether to carry out a grafting reaction. The amino groups at the end of the terminal amino polyether molecular chain chemically bond with oxygen-containing active groups to form a flexible molecular brush layer on the fiber surface, thus obtaining grafted PE fiber. Step S3: Immerse the grafted PE fiber in the mineralization precursor solution, utilize the active sites on the flexible molecular brush layer to chelate calcium ions, induce the growth of calcium-containing mineral seeds in situ, and obtain the product after drying.

3. The UHPC high-performance powder material according to claim 2, characterized in that, In step S1, the surface activation treatment employs one of the following: low-temperature plasma treatment, high-energy ray irradiation, or chemical oxidation treatment; the diameter of the PE fiber filament is... , length is Tensile strength elastic modulus .

4. The UHPC high-performance powder material according to claim 2, characterized in that, In step S2, the terminal amino polyether is a polyetheramine having copolymer segments of ethylene oxide and propylene oxide; the weight-average molecular weight of the terminal amino polyether is ; and the molar percentage of propylene oxide in the copolymer segment is .

5. The UHPC high-performance powder material according to claim 2, characterized in that, In step S2, the conditions for the grafting reaction are: the reaction solvent is ethanol or water, and the reaction temperature is... The reaction time is The ratio of the pre-activated PE fiber to the reaction solvent is 1: The concentration of the amino-terminated polyether in the reaction solvent is An amidation condensing agent, composed of EDC·HCl and NHS, is added during the reaction process. The concentration of EDC·HCl in the reaction solution is [missing information]. The concentration of NHS in the reaction solution is .

6. The UHPC high-performance powder material according to claim 2, characterized in that, In step S3, the mineralization precursor solution is a saturated calcium hydroxide solution or a buffer solution containing a calcium salt; the calcium salt is selected from at least one of calcium nitrate, calcium chloride, or calcium acetate, and the concentration of calcium ions in the solution is [missing information]. .

7. The UHPC high-performance powder material according to claim 2, characterized in that, In step S3, the ratio of grafted fibers to mineralization precursor solution is 1: ; The immersion time of the fiber in the mineralized precursor solution is During this period, the pH value of the solution is maintained at [value missing]. .

8. The UHPC high-performance powder material according to claim 1, characterized in that, The cementitious material includes silicate cement, silica fume, and ultrafine mineral powder; the aggregate is quartz sand; and the chemical admixture is powdered polycarboxylate superplasticizer.

9. One claim The method for preparing UHPC high-performance powder material according to any one of the claims is characterized in that, Includes the following steps: (1) The cementitious material, aggregate and chemical admixture are put into a mixer and dry-mixed to obtain a premix; (2) The surface-functionalized modified PE fibers are added to the premix by airflow dispersion or batch feeding; (3) Continue stirring until the fibers are evenly dispersed in the powder, then discharge and package.

10. The preparation method according to claim 9, characterized in that, In step (3), the stirring is performed using a forced planetary mixer or a plow mixer, with a stirring speed of [missing information]. The stirring time is .

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