A woven fiber reinforced alkali-activated ultra-high performance concrete panel and a preparation method and application thereof

Abstract

This invention belongs to the field of concrete composite materials technology, and particularly relates to a woven fiber-reinforced alkali-activated ultra-high performance concrete slab, its preparation method, and its application. The slab includes a fiber reinforcement layer and an alkali-activated ultra-high performance concrete base layer. The fiber reinforcement layer comprises a mesh-like arrangement of fibers, and the alkali-activated ultra-high performance concrete base layer contains a mixture of long and short fibers. The alkali-activated ultra-high performance concrete base layer is connected to the surface of the fiber reinforcement layer, and its thickness is 10mm-20mm. The fiber reinforcement layer and alkali-activated ultra-high performance concrete selected in this application both possess the advantages of high strength, high durability, and good fire resistance. By combining them to form a composite slab, the prepared woven fiber-reinforced alkali-activated ultra-high performance concrete slab exhibits very high strength.

Description

Technical Field

[0001] This invention belongs to the field of concrete composite materials technology, and particularly relates to a braided fiber reinforced alkali-activated ultra-high performance concrete slab, its preparation method and application. Background Technology

[0002] Reinforced concrete structures account for over 80% of bridge construction in my country, meeting widespread industrial demand. However, due to the poor corrosion resistance and high-temperature resistance of concrete structures, concrete structures and components are prone to damage during use, leading to direct exposure of reinforcing steel to the air and a significant reduction in load-bearing capacity. Especially in high-temperature fire environments, concrete structures are prone to peeling and cracking. If timely and effective reinforcement and repair are not carried out, the service safety of the concrete structure will ultimately be jeopardized.

[0003] Ultra-high performance concrete (UHPC) has better workability than ordinary concrete, making it a popular choice for many demanding construction projects. UHPC typically has a tensile strength greater than 7 MPa and a compressive strength greater than 120 MPa, and it also has good ductility. However, due to the dense structure of UHPC, the higher the strength, the greater the chance of it bursting. Under high temperature conditions, the probability of bursting is much higher than that of ordinary concrete.

[0004] Carbon fiber reinforced polymer (CFRP) composites are widely used in structural reinforcement due to their lightweight and high strength. Traditional reinforcement methods typically involve bonding CFRP sheets to the concrete surface using organic structural adhesives (such as epoxy resin) to share the load. However, using organic adhesives as binders presents challenges such as poor heat resistance and aging, leading to interface delamination and poor durability. New technologies are needed to overcome these difficulties. Textile reinforced concrete (TRC) is a novel composite material combining FRP fabric with cementitious materials. It not only possesses the excellent mechanical properties of FRP but also exhibits significantly improved interface durability due to the use of inorganic binders. However, traditional reinforcement methods suffer from the aging and heat resistance issues of organic structural adhesives (such as epoxy resin), resulting in poor reinforcement effectiveness. Furthermore, the problem of ultra-high performance concrete (UHPC) being prone to cracking under high-temperature conditions during fires remains unresolved, posing a safety hazard.

[0005] Therefore, in order to solve these problems, it is necessary to explore a new type of high-performance high-temperature resistant material to replace UHPC. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that existing composite concrete structures have defects such as poor reinforcement effect and easy cracking. To overcome the shortcomings and defects mentioned in the background art, the present invention provides a woven fiber reinforced alkali-activated ultra-high performance concrete slab, its preparation method and application.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] A woven fiber-reinforced alkali-activated ultra-high performance concrete slab, characterized in that the slab includes a fiber reinforcement layer and an alkali-activated ultra-high performance concrete base layer, the fiber reinforcement layer includes a mesh-like fiber web, the alkali-activated ultra-high performance concrete base layer contains mixed long and short fibers, the alkali-activated ultra-high performance concrete base layer is connected to the surface of the fiber reinforcement layer, and the thickness of the alkali-activated ultra-high performance concrete base layer is 10mm-20mm.

[0009] The bonding performance between alkali-activated ultra-high performance concrete (UHPC) and the fiber-reinforced layer is comparable to that of UHPC at room temperature. Alkali-activated UHPC exhibits good fire resistance, while the two materials also demonstrate excellent bond strength. Although the bond performance between alkali-activated UHPC and the fiber-reinforced layer mesh decreases to some extent with increasing temperature at high temperatures, it remains significantly better than that of UHPC. Therefore, reinforced panels with an alkali-activated UHPC base and a fiber-reinforced layer exhibit stronger high-temperature resistance.

[0010] Preferably, the mixed long and short fibers include long fibers and short fibers. The long fibers have a length of 13mm-20mm and are added at 1.5%-2% of the total volumetric admixture of ultra-high performance concrete. The short fibers have a length of 5mm-8mm and are added at 1.5%-2% of the total volumetric admixture of ultra-high performance concrete. The ratio of long to short fiber length is 1.628-4. The fiber type of the long and short fibers includes straight steel fibers.

[0011] The long and short fibers used in this application are straight steel fibers. High-deformation-ratio steel fibers are not as effective as straight steel fibers in enhancing the compressive and flexural strength of UHPGC. Corrugated steel fibers have a high thinning ratio and higher mechanical interlocking and friction, but the UHPGC matrix is ​​brittle and cannot withstand the higher stress generated at the matrix interface by the corrugated fibers, causing the specimen matrix to fail prematurely before the fibers are pulled out.

[0012] This application further distinguishes between doped long and short fibers. Short steel fibers can suppress the formation of microcracks, while long steel fibers have high strength and stiffness, which can suppress large cracks and improve the crack strength of the material. The two types of fibers work synergistically, and the strength and ductility are significantly improved compared to single fibers. The compressive strength of 3% short fiber doping is 127.83 MPa, the compressive strength of 3% long fiber doping is 151.57 MPa, and the compressive strength of 1.5% each of long and short fibers reaches 157.68 MPa.

[0013] Preferably, the alkali-activated ultra-high performance concrete base layer comprises the following components by weight:

[0014] 520-640 parts of slag;

[0015] 130-160 parts fly ash;

[0016] 200-350 parts silica fume;

[0017] Surfactant 480-510 parts;

[0018] 234-312 parts of long and short fibers;

[0019] 150-160 parts of 20-40 mesh quartz sand;

[0020] 210-220 parts of 40-70 mesh quartz sand;

[0021] 380-390 parts of 70-110 mesh quartz sand;

[0022] 270-280 parts of quartz sand with a mesh size of 110 or higher.

[0023] Ultra-high performance geopolymer concrete (UHPGC) is a type of green cementitious material formed by chemically activating aluminosilicate minerals (mainly metallurgical slag, coal-fired power plant waste, municipal solid waste, etc.) and curing them at room temperature or high temperature. Unlike the reaction products of silicate cement, the reaction products of geopolymer cementitious materials are generally more dense in phase, exhibiting high early strength and corrosion resistance. Although the preparation of the activator consumes some energy, the overall energy consumption and carbon emissions of geopolymer preparation are lower than those of silicate cement production because the high-temperature calcination of raw materials can be avoided. Therefore, using geopolymer cement to replace silicate cement to prepare ultra-high performance geopolymer concrete (UHPGC) has significant energy-saving and emission-reduction effects.

[0024] This application re-selects and re-formulates the raw materials for alkali-activated ultra-high performance concrete. Among them, silica fume plays an important role in chemical filling and densification through its physical properties as an ultrafine powder, thus playing a key role in improving the mechanical and long-term performance of concrete. At the same time, the appropriate addition of silica fume helps to improve flowability, prolong setting time and increase matrix strength. This application selects quartz sand of different mesh sizes as raw materials. Quartz sand of different mesh sizes can fill the voids in the material, adjust the particle distribution and internal structure of the material to improve the density of concrete, thereby enhancing its durability.

[0025] Preferably, the activator comprises NaOH powder, water, and Na2SiO3 solution, wherein the modulus of the Na2SiO3 solution is 2.2-2.3; wherein, by mass, the activator comprises 340-350 parts of Na2SiO3 solution, 40-50 parts of NaOH powder, and 100-110 parts of water.

[0026] The alkali activator used in this application is a mixed solution of caustic soda (NaOH) and water glass. The chemical composition of sodium silicate water glass can be expressed as Na2O%nSiO2, where n is the modulus of water glass. The value of n is adjusted by adding sodium hydroxide, thereby adjusting the concentration of the alkali activator to suit the alkali-activated ultra-high performance concrete base layer of this application.

[0027] Slag, fly ash, or silica fume serve as precursors for alkali-activated ultra-high performance concrete base layers, while quartz sand acts as aggregate to fill the voids in the concrete.

[0028] Preferably, the fiber reinforcement layer is made of biaxial carbon fiber.

[0029] Under the same technical concept, this application also provides a method for preparing woven fiber reinforced alkali-activated ultra-high performance concrete slabs, including the following steps:

[0030] (1) Preparation of alkali-activated ultra-high performance concrete;

[0031] (2) Laying a mesh-like fiber reinforcement layer;

[0032] (3) The alkali-activated ultra-high performance concrete is poured onto the fiber-reinforced layer and leveled by vibration to obtain woven fiber-reinforced alkali-activated ultra-high performance concrete slabs.

[0033] Preferably, the method for preparing alkali-activated ultra-high performance concrete specifically includes the following steps:

[0034] Slag, fly ash, and silica fume are mixed, quartz sand is added and dry mixing is continued, then an activator is added and wet mixing is carried out. Mixed long and short fibers are added and stirring is continued to obtain alkali-activated ultra-high performance concrete.

[0035] Under the same technical concept, this application also provides an application of woven fiber reinforced alkali-activated ultra-high performance concrete slabs, wherein the woven fiber reinforced alkali-activated ultra-high performance concrete slabs are disposed on the surface of beams for reinforcing beams.

[0036] Preferably, the preparation method for the material disposed on the surface of the beam specifically includes the following steps:

[0037] (1) Prepare alkali-activated ultra-high performance concrete by placing the fiber reinforcement layer at the bottom of the beam;

[0038] (2) The alkali-activated ultra-high performance concrete is sprayed onto the surface of the fiber-reinforced layer to form a woven fiber-reinforced alkali-activated ultra-high performance concrete slab fixed to the bottom of the beam, thus completing the reinforcement.

[0039] Preferably, the ends of the woven fiber-reinforced alkali-activated ultra-high performance concrete slab are anchored to the beam using bolts.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] (1) The fiber-reinforced layer and alkali-activated ultra-high performance concrete selected in this application have the advantages of high strength, high durability and good fire resistance. This application combines them to form a composite board, and the woven fiber-reinforced alkali-activated ultra-high performance concrete board prepared can have very high strength.

[0042] (2) The plate material of this application overcomes the obvious shortcomings of UHPC being prone to cracking at high temperatures and the mechanical properties of alkali-activated materials not meeting the high performance requirements. It ensures reinforcement efficiency and improves structural durability in high-temperature environments during fires. The fiber mesh strengthens the crack bridging effect, improves the crack resistance and ductility of the structure, and can also effectively resist the deterioration of the original structure and reinforcement materials by high-temperature environments.

[0043] (3) The woven fiber reinforced alkali-activated ultra-high performance concrete slab provided in this application can be applied to the reinforcement of various beams, walls and other materials. It is easy to construct and can quickly and easily reinforce and maintain damaged beams, and has high industrial value. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is the construction design drawing of the woven fiber reinforced alkali-activated ultra-high performance concrete slab of Example 1;

[0046] Figure 2 This is a flowchart of the preparation process of alkali-activated ultra-high performance concrete in Example 1; Detailed Implementation

[0047] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0048] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0049] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0050] Example 1:

[0051] A woven fiber-reinforced alkali-activated ultra-high performance concrete slab is disclosed. The slab includes a fiber reinforcement layer and an alkali-activated ultra-high performance concrete base layer. The fiber reinforcement layer is mesh-like, and the alkali-activated ultra-high performance concrete base layer contains mixed long and short fibers. The thickness of the alkali-activated ultra-high performance concrete base layer is 10-20 mm, and it is connected to the surface of the fiber reinforcement layer.

[0052] The long and short fibers are straight steel fibers. The long fibers are 13 mm long and 0.12 mm in diameter, and the short fibers are also 13 mm long and 0.12 mm in diameter. The total volumetric content of the long and short fibers in the ultra-high performance concrete is 1.5% each.

[0053] The fiber reinforcement layer is made of carbon fiber reinforced polymer (CFRP) with a thickness of 0.22 mm, a mesh spacing of 5 mm, a tensile strength of 2300 MPa, and a tensile modulus of 230 GPa.

[0054] Alkali-activated ultra-high performance concrete includes the following components:

[0055] 560 kg of slag;

[0056] 140 kg of fly ash;

[0057] 300 kg of silica fume;

[0058] Straight steel long fiber: 117kg-156kg; Straight steel short fiber: 117kg-156kg;

[0059] The activator includes NaOH solution and Na2SiO3 solution, wherein the concentration of NaOH solution is 98.0±1% and the amount added is 43.8 kg; water is 107.5 kg; the molar ratio of Na2O / SiO2 in Na2SiO3 solution is 2.3 and the modulus is 2.25; the amount added is 340.6 kg.

[0060] 800 mesh quartz sand 273kg; 70-110 mesh quartz sand 381kg; 40-70 mesh quartz sand 211kg; 20-40 mesh quartz sand 152kg;

[0061] The specific proportions are shown in Table 1 below:

[0062] Table 1: Components of Alkali-Activated Ultra-High Performance Concrete

[0063]

[0064] Where B represents the precursor raw materials, which is the total mass of slag, fly ash and silica fume.

[0065] Preparation methods of alkali-activated ultra-high performance concrete, such as Figure 2 As shown, the specific steps include:

[0066] The surfactant was prepared the day before: NaOH solution was prepared using NaOH flakes, with a concentration of 98.0±1%; the SiO2 / Na2O molar ratio of Na2SiO3 was approximately 2.3, and the water content was approximately 56.5%;

[0067] The activator is obtained by mixing two alkaline solutions, NaOH and Na2SiO3, in a molar ratio of 2.249.

[0068] First, slag, fly ash, and mixed silica fume are combined to form a mixed precursor. The mixture is dry-mixed for 2 minutes. The silica fume accounts for 30% of the mass of the mixed precursor, and the ratio of slag to fly ash is 4:1.

[0069] Then add quartz sand and stir for 1 minute. After dry mixing, add activator and wet mix for 4 minutes. Finally, add long and short straight steel fibers through a 6mm steel sieve within 5 minutes, and continue stirring for 4 minutes to ensure effective distribution.

[0070] A method for preparing woven fiber reinforced alkali-activated ultra-high performance concrete slabs includes the following steps:

[0071] (1) Preparation of alkali-activated ultra-high performance concrete;

[0072] (2) Laying a mesh-like fiber reinforcement layer;

[0073] (3) The alkali-activated ultra-high performance concrete is poured onto the fiber-reinforced layer and leveled by vibration to obtain woven fiber-reinforced alkali-activated ultra-high performance concrete slabs.

[0074] The preparation method of alkali-activated ultra-high performance concrete specifically includes the following steps:

[0075] An application of woven fiber-reinforced alkali-activated ultra-high performance concrete slabs, wherein the woven fiber-reinforced alkali-activated ultra-high performance concrete slabs are applied to the surface of beams to reinforce them. A schematic diagram of the reinforcement is shown below. Figure 1 As shown.

[0076] The preparation method for setting on the surface of beam material specifically includes the following steps:

[0077] (1) Prepare alkali-activated ultra-high performance concrete by placing the fiber reinforcement layer at the bottom of the beam;

[0078] (2) The alkali-activated ultra-high performance concrete is sprayed onto the surface of the fiber-reinforced layer to form a woven fiber-reinforced alkali-activated ultra-high performance concrete slab fixed to the bottom of the beam, thus completing the reinforcement.

[0079] The ends of the woven fiber-reinforced alkali-activated ultra-high performance concrete slabs are anchored to the beams using bolts.

[0080] Comparative Example 1:

[0081] The raw materials and methods used in Comparative Example 1 are the same as those in Example 1. The difference is that the alkali-activated ultra-high performance concrete used in Comparative Example 1 does not contain long or short fibers. The specific mix proportions are shown in Table 2 below:

[0082] Table 1: Comparative Components of Alkali-Activated Ultra-High Performance Concrete

[0083]

[0084] Where B represents the precursor raw materials, which is the total mass of slag, fly ash and silica fume.

[0085] High-temperature tests were conducted on the woven fiber reinforced alkali-activated ultra-high performance concrete slabs of Example 1 and Comparative Example 1, as well as the woven fiber reinforced alkali-activated ultra-high performance concrete slabs fixed to the bottom of the beams formed thereon. The experimental results are shown in Table 1.

[0086]

[0087]

[0088] (Note: N represents no steel fiber added, S represents mixed steel fibers of 1.5% each (13mm long and 6mm short), and the number after N / S represents the temperature at which the steel fibers are damaged by high temperature.)

[0089] The results verified that they exhibited excellent high-temperature resistance under high-temperature conditions. As the temperature increased, the strengths of each component decreased, while the strengths of the steel fiber-mixed components increased at all temperatures compared to the unmixed components.

Claims

1. A woven fiber-reinforced alkali-activated ultra-high performance concrete slab, characterized in that, The plate consists of a fiber-reinforced layer and an alkali-activated ultra-high performance concrete base layer. The fiber-reinforced layer comprises a mesh-like fiber network, and the material of the fiber-reinforced layer is biaxial carbon fiber. The alkali-activated ultra-high performance concrete base layer contains a mixture of long and short fibers, which are connected to the surface of the fiber-reinforced layer. The thickness of the alkali-activated ultra-high performance concrete base layer is 10mm-20mm. The mixture of long and short fibers includes both long and short fibers. The long fibers have a length of 13mm-20mm and are added at 1.5%-2% of the total volumetric admixture of the ultra-high performance concrete. The short fibers have a length of 5mm-8mm and are also added at 1.5%-2% of the total volumetric admixture of the ultra-high performance concrete. The ratio of long to short fiber length is 1.628-4. The type of fiber used for both the long and short fibers is straight steel fiber. The alkali-activated ultra-high performance concrete base layer, by mass proportion, includes the following components: 520-640 parts of slag; 130-160 parts fly ash; 200-350 parts silica fume; Surfactant 480-510 parts; 234-312 parts of long and short fibers; 150-160 parts of 20-40 mesh quartz sand; 210-220 parts of 40-70 mesh quartz sand; 380-390 parts of 70-110 mesh quartz sand; The active ingredient comprises 270-280 parts of quartz sand with a mesh size of 110 or larger, and the active ingredient comprises NaOH powder, water and Na2SiO3 solution, wherein the modulus of the Na2SiO3 solution is 2.2-2.3; wherein, by mass, the active ingredient comprises 340-350 parts of Na2SiO3 solution, 40-50 parts of NaOH powder and 100-110 parts of water.

2. A method for preparing woven fiber reinforced alkali-activated ultra-high performance concrete slabs as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of alkali-activated ultra-high performance concrete; (2) Laying a mesh-like fiber reinforcement layer; (3) The alkali-activated ultra-high performance concrete is poured onto the fiber-reinforced layer and leveled by vibration to obtain woven fiber-reinforced alkali-activated ultra-high performance concrete slabs.

3. The preparation method according to claim 2, characterized in that, The method for preparing alkali-activated ultra-high performance concrete specifically includes the following steps: Slag, fly ash, and silica fume are mixed, quartz sand is added and dry mixing is continued, then an activator is added and wet mixing is carried out. Mixed long and short fibers are added and stirring is continued to obtain alkali-activated ultra-high performance concrete.

4. An application of the woven fiber reinforced alkali-activated ultra-high performance concrete slab as described in claim 1, characterized in that, The woven fiber-reinforced alkali-activated ultra-high performance concrete slab is applied to the surface of the beam to reinforce it.

5. The application as described in claim 4, characterized in that, The preparation method for the material disposed on the surface of the beam specifically includes the following steps: (1) Prepare alkali-activated ultra-high performance concrete by placing the fiber reinforcement layer at the bottom of the beam; (2) The alkali-activated ultra-high performance concrete is sprayed onto the surface of the fiber-reinforced layer to form a woven fiber-reinforced alkali-activated ultra-high performance concrete slab fixed to the bottom of the beam, thus completing the reinforcement.

6. The application as described in claim 4 or 5, characterized in that, The ends of the woven fiber-reinforced alkali-activated ultra-high performance concrete slab are anchored to the beam with bolts.

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