A high-fluidity, low-shrinkage, high-toughness fiber concrete and its preparation method

Abstract

The present invention provides a high-fluidity, low-shrinkage, and high-toughness fiber concrete. The concrete of the present invention comprises cement, viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixtures, mullite sand, basalt coarse aggregates, multi-scale hybrid fibers, a special super-dispersing viscosity-reducing admixture, and water; by utilizing the "ball bearing effect" of fly ash microspheres in the viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixtures and the viscosity-reducing effect of the special super-dispersing viscosity-reducing admixture, the workability of the concrete mixture is optimized, the compactness and homogeneity of the concrete are improved, and the self-compacting and high-fluidity design of high-strength concrete is realized; multi-scale synergistically enhances the toughness of the fiber concrete: by utilizing the small-scale effect of gas-phase nano-SiO2 particles, the toughening design of the fiber concrete at the molecular scale can be realized; the high-fluidity, high elastic modulus, high-toughness, and low-shrinkage fiber concrete of the present invention has the characteristics of high strength, self-compacting, and high durability, solves the problem of easy downward deflection of the mid-span of large-span concrete box arch bridges, and has important practical application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a high-fluidity, low-shrinkage, and high-toughness fiber concrete and a preparation method thereof. Background Art

[0002] China has currently become a major bridge country in the world, and many bridges have ranked among the top in the world in terms of bridge span. In recent years, bridge engineering has developed rapidly, the scale of bridges has been continuously expanded, and a large number of new long-span bridges have emerged. Due to its reasonable force characteristics, magnificent bridge type, large spanning ability, good environmental coordination, and high economic benefits, arch bridges have been unanimously recognized by the engineering community and have become one of the frequently preferred bridge types in design. However, the terrain in western China is complex, with many high mountains and deep valleys. Therefore, arch bridges have a relatively large span in design, while the arch rings formed by ordinary concrete have a high self-weight and low toughness, and are prone to problems such as mid-span deflection, making it difficult to meet the requirements of mountain bridge construction.

[0003] Fiber concrete is a new type of multiphase composite material formed by incorporating randomly distributed fibers into ordinary concrete. The randomly distributed fibers incorporated into the concrete can effectively inhibit the expansion of internal micro-cracks and the formation of macro-cracks in the concrete. Compared with ordinary concrete, the tensile, compressive, shear, and flexural properties of fiber concrete have been greatly improved, and at the same time, its toughness, durability, wear resistance, fatigue resistance, impact resistance, etc. have also been improved, turning the originally brittle concrete material into a composite material with certain plasticity. Therefore, fiber concrete is very suitable for application in bridge arch structures and has gradually been recognized and widely used in different types of buildings, such as houses, road surfaces, water conservancy projects, etc.

[0004] At present, C80 - C100 concrete at home and abroad is prone to cracking due to high heat of hydration, large shrinkage, poor toughness, etc. Moreover, the viscosity of the concrete is high and the fluidity is poor, which cannot meet the requirements of high fluidity for densely reinforced concrete. UHPC materials have the properties of ultra-high strength (>120 MPa), high toughness, and high durability, but the cement, silica fume and other cementitious materials used in UHPC materials are very high, and the water-cement ratio is extremely low, resulting in problems such as large shrinkage, easy cracking, and extremely high cost, which limit its application.

[0005] Based on the existing defects of fiber concrete, it is necessary to improve it. Summary of the Invention

[0006] In view of this, the present invention provides a high-fluidity, low-shrinkage, and high-toughness fiber concrete and a preparation method thereof to solve the defects existing in the prior art.

[0007] In a first aspect, the present invention provides a highly fluid, low shrinkage, and high toughness fiber concrete, comprising the following raw materials: 400 - 550 kg / m of cement 3 , 100 - 300 kg / m of viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture 3 , 600 - 900 kg / m of mullite sand 3 , 1000 - 1200 kg / m of basalt coarse aggregate 3 , 10 - 100 kg / m of multi-scale hybrid fiber 3 , 6 - 10 kg / m of super-dispersing viscosity-reducing special admixture 3 , 5 - 25 kg / m of expansive agent 3 , 120 - 180 kg / m of water 3 ;

[0008] Among them, the super-dispersing viscosity-reducing special admixture includes an air-entraining water reducer and an anti-sludge viscosity-reducing water reducer.

[0009] Preferably, for the highly fluid, low shrinkage, and high toughness fiber concrete, the preparation method of the air-entraining water reducer comprises the following steps:

[0010] Add sodium metabisulfite and liquid alkali to water for reaction to obtain a sodium bisulfite solution;

[0011] Add acetone, dihydroeugenol, and an auxiliary agent to the sodium bisulfite solution. The sulfonation reaction occurs between sodium bisulfite and acetone to form α-olefin sulfonate;

[0012] After the sulfonation reaction ends, add formaldehyde for condensation reaction. After the condensation reaction is completed, add a foam stabilizer to obtain the air-entraining water reducer.

[0013] Preferably, for the highly fluid, low shrinkage, and high toughness fiber concrete, the preparation method of the anti-sludge viscosity-reducing water reducer comprises the following steps:

[0014] Using epichlorohydrin and methyl allyl polyoxyethylene ether as raw materials, prepare a methyl allyl polyoxyethylene chlorohydrin ether intermediate through a ring-opening polymerization reaction;

[0015] Using dihydroeugenol and the methyl allyl polyoxyethylene chlorohydrin ether intermediate as raw materials, prepare a dihydroeugenol-grafted polyether macromonomer;

[0016] Using the dihydroeugenol-grafted polyether macromonomer and acrylic acid as raw materials, prepare the anti-sludge viscosity-reducing water reducer.

[0017] Preferably, for the highly fluid, low shrinkage, and high toughness fiber concrete, the viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture includes a mixture of mineral powder, fly ash microspheres, silica fume, and C 4 AF.

[0018] Preferably, for the high-fluidity, low-shrinkage, and high-toughness fiber concrete, the specific surface area of the mineral powder is 300 - 900 m 2 / kg; the SiO 2 mass content of silica fume is ≥95%, the specific surface area is ≥15500 m 2 / kg, and the 28-day activity index is ≥100%; the calcination temperature of C 4 AF is 1340 - 1390 °C, its specific surface area is 350 - 500 m 2 / kg, and the aluminum doping content is 17 - 20%.

[0019] Preferably, for the high-fluidity, low-shrinkage, and high-toughness fiber concrete, the multi-scale hybrid fibers include a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic fumed nano-SiO 2 particles. Among them, the mass ratio of the copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic fumed nano-SiO 2 particles is 100:(0 - 40):(0 - 30):(0 - 10).

[0020] Preferably, for the high-fluidity, low-shrinkage, and high-toughness fiber concrete, the nominal length of the copper-plated steel fibers is 6 - 13 mm, the equivalent diameter is 0.10 - 0.20 mm, the fracture strength is ≥2000 MPa, and the elastic modulus is 160 - 220 GPa; the nominal length of the multi-anchor steel fibers is 10 - 16 mm, the equivalent diameter is 0.18 - 0.25 mm, the fracture strength is ≥1000 MPa, and the elastic modulus is 210 - 230 GPa; the nominal length of the temperature-shrinkable organic fibers is 6 - 12 mm, the equivalent diameter is 0.10 - 0.20 mm, the fracture strength is ≥550 MPa, and the elastic modulus is ≥8 GPa; the specific surface area of the hydrophilic fumed nano-SiO 2 particles is ≥380 m 2 / g.

[0021] Preferably, for the high-fluidity, low-shrinkage, and high-toughness fiber concrete, the cement is P·II 52.5 Portland cement;

[0022] The expansive agent is azodicarbonamide expansive agent;

[0023] The saturated surface dry water absorption rate of the mullite sand is 1% - 8%, the particle size is 20 - 40 mm, and the apparent density is 2300 - 2600 kg / m 3 ;

[0024] The water absorption rate of the basalt coarse aggregate is 1% - 5%, and it is a high-strength aggregate with a continuous gradation of 5 - 16 mm. The apparent density of the basalt coarse aggregate is 2800 - 3100 kg / m 3 .

[0025] Preferably, for the high-fluidity, low-shrinkage, and high-toughness fiber concrete, the super-dispersing viscosity-reducing special admixture further includes an ionic adsorption-dispersing defoaming agent, a viscosity modifier, and a retarder.

[0026] In a second aspect, the present invention also provides a method for preparing the high-fluidity, low-shrinkage, and high-toughness fiber concrete, comprising the following steps:

[0027] Mix cement, viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixtures, an expansive agent, mullite sand, and basalt coarse aggregate, then stir, add water and the super-dispersing viscosity-reducing special admixture, continue stirring, then add multi-scale hybrid fibers, mold, vibrate, and form, and cover the surface with an impermeable film for film curing;

[0028] After demolding, perform standard curing to obtain the high-fluidity, low-shrinkage, and high-toughness fiber concrete.

[0029] The present invention has the following beneficial effects compared with the prior art:

[0030] 1. The high-fluidity, low-shrinkage, and high-toughness fiber concrete of the present invention includes cement, viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixtures, mullite sand, basalt coarse aggregate, multi-scale hybrid fibers, a super-dispersing viscosity-reducing special admixture, and water; it utilizes the "ball bearing effect" of fly ash microspheres in the viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixtures and the viscosity-reducing effect of the super-dispersing viscosity-reducing special admixture to optimize the workability of the concrete mixture, improve the compactness and homogeneity of the concrete, and achieve self-compacting and high-fluidity design of high-strength concrete; multi-scale synergistically enhances the toughness of the fiber concrete: the small-scale effect of gas-phase nano-SiO 2 particles can achieve toughness-enhancing design of the fiber concrete at the molecular scale; C 4The AF component releases a large amount of Al in the early stage of hydration, enters the C-S-H gel to form a large amount of C-(A)-S-H gel, increases the chain length of the Si-O chain in the gel, and effectively improves the toughness of fiber concrete at the molecular scale; by utilizing the characteristics of the temperature-shrinkable fiber that shrinks at high temperature and applies pre-compressive stress, toughening of concrete is achieved at the micron scale; at the same time, adding copper-plated steel fibers and multi-anchor steel fibers to the concrete realizes the toughening of concrete at the macroscopic scale; by using high-modulus mullite sand and basalt coarse aggregates and preparing high-modulus fiber concrete with a compressive strength grade of C80 - C100 and an elastic modulus ≥ 45 GPa according to the dense packing design principle; by utilizing the internal curing effect of mullite sand and basalt coarse aggregates, combined with the compensating shrinkage of azodicarbonamide expander, the problem of large shrinkage of high-strength fiber concrete is improved to a certain extent. At the same time, combined with the premix process, it promotes the formation of a high-strength and dense C-S-H gel interfacial transition zone around the mullite sand, reduces the porosity, solves the defect problem between the paste and the interface, and improves the mechanical properties and durability of the high-fluidity, high-elastic modulus, high-toughness and low-shrinkage fiber concrete.

[0031] 2. The apparent density of the high-fluidity, high-elastic modulus, high-toughness and low-shrinkage fiber concrete obtained by the present invention is 2300 - 2600 kg / m 3 , and at the same time, the compressive strength grade can reach above C80, and it has good workability, mechanical properties and volume stability, can effectively improve the toughness, elastic modulus and durability of concrete components, and has important practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 is the structural formula of the air-entraining water reducer of the present invention;

[0034] Figure 2 is the infrared spectrum (IR) diagram of the air-entraining water reducer (DAFS) prepared by the present invention;

[0035] Figure 3 is the nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) diagram of the air-entraining water reducer (DAFS) prepared by the present invention;

[0036] Figure 4 is the infrared spectrum (IR) diagram of the anti-sludge viscosity-reducing water reducer (DPCE) prepared by the present invention;

[0037] Figure 5 1H NMR spectrum of the anti-sludging viscosity-reducing water reducer (DPCE) prepared according to the present invention 1 1H NMR Specific embodiments

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". The various embodiments of the present invention may exist in a range form; it should be understood that the description in a range form is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0040] The embodiments of the present application provide a high-fluidity, low-shrinkage, and high-toughness fiber concrete, comprising the following raw materials: 400 - 550 kg / m 3 of cement, 100 - 300 kg / m 3 of viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture, 600 - 900 kg / m 3 of mullite sand, 1000 - 1200 kg / m 3 of basalt coarse aggregate, 10 - 100 kg / m 3 of multi-scale hybrid fiber, 6 - 10 kg / m 3 of super-dispersed viscosity-reducing special admixture, 5 - 25 kg / m 3 of expansive agent, and 120 - 180 kg / m 3 of water;

[0041] Among them, the super-dispersed viscosity-reducing special admixture includes an air-entraining water reducer and an anti-sludging viscosity-reducing water reducer.

[0042] The high-fluidity, low-shrinkage, and high-toughness fiber concrete of the present invention comprises cement, viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixtures, mullite sand, basalt coarse aggregates, multi-scale hybrid fibers, a special super-dispersing viscosity-reducing admixture, and water. By adjusting the dosage of fly ash microspheres in the viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixtures and the dosage of the special super-dispersing viscosity-reducing admixture, the working performance and compactness of the concrete are regulated to achieve self-compacting and high-fluidity design of the concrete. The incorporation of multi-scale hybrid fibers can enhance the toughness of the prepared concrete at multiple scales such as macroscopic, micron, nano, and molecular scales, realizing the high-toughness design of fiber concrete. Additionally, by utilizing the internal curing effect of water-saturated pre-wetted high-strength mullite sand and basalt coarse aggregates, the shrinkage of the concrete is reduced, the volume stability and crack resistance of the concrete are improved, and the elastic modulus of the concrete is increased to prepare high-fluidity, low-shrinkage, high-toughness, and high-modulus concrete with an elastic modulus ≥ 45 GPa. Moreover, the thermally shrinking organic fiber component in the multi-scale hybrid fibers shrinks due to heat during the early hydration stage of the cementitious paste, forming multiple pre-compression stress fields inside the concrete, improving the internal stress environment of the concrete, thereby enhancing the crack resistance of the concrete. It synergistically improves the volume stability of the fiber concrete with the internal curing effect of mullite sand and basalt coarse aggregates, further reducing the shrinkage of the concrete and realizing the low-shrinkage design of the fiber concrete. The high-fluidity, high-elastic modulus, high-toughness, and low-shrinkage fiber concrete of the present invention combines high strength, self-compacting, and high-durability properties, solves the problem of easy downward deflection of the mid-span of large-span concrete box arch bridges, and has important practical application value.

[0043] In some embodiments, the preparation method of the air-entraining water reducer comprises the following steps:

[0044] S1. Sodium metabisulfite and liquid caustic soda are added to water to obtain a sodium bisulfite solution;

[0045] S2. Acetone, dihydroeugenol, and an auxiliary agent are added to the sodium bisulfite solution. The sulfonation reaction occurs between sodium bisulfite and acetone to generate α-olefin sulfonate;

[0046] S3. After the sulfonation reaction ends, formaldehyde is added for a condensation reaction. After the condensation reaction is completed, a foam stabilizer is added to obtain the air-entraining water reducer.

[0047] Specifically, in step S2, after the sulfonation reaction ends, formaldehyde is added for a condensation reaction. Since acetone is in excess in the initial stage of the reaction, formaldehyde and acetone first undergo a crossed aldol condensation reaction to generate a large amount of dihydroxymethylacetone, which then alternately condenses with the previous α-hydroxy sulfonate to form a main chain with a dispersing effect. And dihydroeugenol has only one active hydrogen atom, which dehydrates and polycondenses with dihydroxymethylacetone to both ends of the main chain, obtaining a high molecular polymer with hydrophobic ends.

[0048] The structural formula of the air-entraining water reducer of the present invention is shown as follows:

[0049]

[0050] Among them, x is a positive integer between 30 and 80, and y is a positive integer between 20 and 70.

[0051] Specifically, the structural formula of the high-fluidity, low-shrinkage, and high-toughness fiber concrete prepared by the present invention is as Figure 1 shown. Its preparation method includes: adding dihydroeugenol (2-methoxy-4-propylphenol) and liquid alkali (such as sodium hydroxide solution) to water, making the pH value of the base material strongly alkaline, and then adding sodium metabisulfite to dissolve it to obtain a saturated sodium bisulfite solution; then dropping acetone to react with the saturated sodium bisulfite solution to generate sodium α-olefin sulfonate through sulfonation reaction; after the sulfonation reaction ends, immediately raise the temperature and drop formaldehyde for condensation reaction. At the initial stage of the reaction, the generated dihydroxymethylacetone, sodium α-olefin sulfonate, and dihydroeugenol are dehydrated and condensed together to obtain the final reaction product, high-fluidity, low-shrinkage, and high-toughness fiber concrete (DAFS). The present invention uses dihydroeugenol as the key raw material, first conducts chemical modification, grafts it to both ends of the sulfonated acetone formaldehyde condensate, and prepares high-fluidity, low-shrinkage, and high-toughness fiber concrete (DAFS).

[0052] In some embodiments, acetone is added to the sodium bisulfite solution, and at the same time, dihydroeugenol and an auxiliary agent are added, and sulfonation reaction is carried out at a temperature not higher than 55 °C to generate sodium α-olefin sulfonate.

[0053] In some embodiments, after the sulfonation reaction ends, formaldehyde is dropped while keeping the temperature unchanged. After dropping formaldehyde, the temperature is raised to 95-99 °C for condensation reaction. During this process, dihydroeugenol is added for dehydration polycondensation, and at the same time, an auxiliary agent is added. After the condensation reaction is completed, a foam-stabilizing agent is added to obtain an air-entraining water-reducing agent.

[0054] Specifically, in the above embodiments, the auxiliary agent is provided by Wuhan Subo New Building Materials Co., Ltd., with the model AM01. Adding the auxiliary agent can make the bubbles inside the concrete doped with DAFS smaller and more stable.

[0055] Specifically, in the above embodiments, the foam-stabilizing agent can be cellulose ether, glutinous rice slurry, etc.

[0056] In some embodiments, after the sulfonation reaction ends, formaldehyde is dropped while keeping the temperature unchanged. After dropping formaldehyde, the temperature is raised to 95-99 °C for condensation reaction to obtain high-fluidity, low-shrinkage, and high-toughness fiber concrete.

[0057] In some embodiments, the mass ratio of dihydroeugenol, sodium metabisulfite, acetone, formaldehyde, and the auxiliary agent is (10-15):(35-40):(45-55):(130-140):(1-5); preferably (10-15):38:50:136:2. In practice, the amounts of acetone and formaldehyde are fixed at 50 g and 136 g respectively.

[0058] In some embodiments, the base includes at least one of sodium hydroxide and potassium hydroxide.

[0059] In some embodiments, when preparing high-fluidity, low-shrinkage, high-toughness fiber concrete (DAFS), during its condensation reaction, in order to prevent the reaction from being difficult to control and to allow acetone and formaldehyde to fully react to generate more dihydroxymethylacetone, the feeding method of formaldehyde is dropwise addition. In this way, at the initial stage of the reaction, acetone can react with formaldehyde through crossed aldol condensation reaction to generate a large amount of dihydroxymethylacetone under the condition of excess acetone.

[0060] In some embodiments, the specific preparation method of high-fluidity, low-shrinkage, high-toughness fiber concrete (DAFS) includes the following steps: sequentially add metered deionized water, sodium hydroxide aqueous solution (liquid alkali) and sodium metabisulfite into a four-necked flask equipped with a stirrer, a condenser and a thermometer. After stirring and dissolving, add acetone and continue stirring for 10 min. Pour the solution of dihydroeugenol previously dissolved with alkali into the reaction solution. After adding a certain proportion of additives according to the total mass of the reaction solution, sulfonate at a temperature not exceeding 55 °C for 1 h. After the sulfonation is completed, keep the temperature unchanged and dropwise add formaldehyde for 3 h. After dropping formaldehyde, raise the temperature to 97 ± 2 °C and condense for 2.5 h. Finally, cool the reactant to room temperature to obtain a high air-entraining water reducer solution (DAFS).

[0061] In some embodiments, the preparation method of the anti-sludge viscosity-reducing water reducer includes the following steps:

[0062] S1. Using epichlorohydrin and allyl polyoxyethylene ether as raw materials, prepare an allyl polyoxyethylene chlorohydrin ether intermediate through ring-opening polymerization reaction;

[0063] S2. Using dihydroeugenol and allyl polyoxyethylene chlorohydrin ether intermediate as raw materials, prepare a dihydroeugenol-grafted polyether macromonomer;

[0064] S3. Using the dihydroeugenol-grafted polyether macromonomer and acrylic acid as raw materials, prepare an anti-sludge viscosity-reducing water reducer.

[0065] In some embodiments, the structural formula of the anti-sludge viscosity-reducing water reducer is as follows:

[0066]

[0067] Among them, a is a positive integer between 5 and 20, b is a positive integer between 20 and 100, c is a positive integer between 1 and 5, and n is a positive integer between 25 and 55.

[0068] Based on the designable characteristics of the molecular structure of polycarboxylate superplasticizers, this invention grafts dihydroeugenol onto the terminal hydroxyl group of methyl allyl polyether macromonomer, uses alkyl to replace the terminal hydroxyl group of the polyether macromonomer and simultaneously introduces benzene ring functional groups to prepare an anti-sludging viscosity-reducing superplasticizer (DPCE).

[0069] In some embodiments, after heating and melting methyl allyl polyoxyethylene ether, boron trifluoride diethyl etherate is added, and epichlorohydrin is dropwise added at 55 - 65 °C, and a methyl allyl polyoxyethylene epichlorohydrin ether intermediate is prepared through ring-opening polymerization reaction; wherein, the molar ratio of boron trifluoride diethyl etherate, epichlorohydrin, and methyl allyl polyoxyethylene ether is (0.03 - 0.05):(1.2 - 1.3):(0.9 - 1.1).

[0070] In some embodiments, after mixing dihydroeugenol and methyl allyl polyoxyethylene epichlorohydrin ether intermediate, the pH is adjusted to 12 - 13, and the reaction is carried out at 75 - 85 °C to obtain a dihydroeugenol-grafted polyether macromonomer.

[0071] In some embodiments, the molar ratio of dihydroeugenol and methyl allyl polyoxyethylene epichlorohydrin ether intermediate is (0.8 - 1.2):(0.8 - 1.2).

[0072] In some embodiments, when preparing the anti-sludging viscosity-reducing superplasticizer (DPCE), the preparation method of the dihydroeugenol-grafted polyether macromonomer includes the following steps:

[0073] S1. First, adopt the acid-catalysis method, using epichlorohydrin (ECH) and methyl allyl polyoxyethylene ether (HPEG, Mx = 2400) as the main raw materials. After heating and melting HPEG, the commonly used boron trifluoride diethyl etherate (Et 2 O·BF 3 ) is used as the catalyst, and ECH is uniformly dropwise added at 60 °C, and a methyl allyl polyoxyethylene epichlorohydrin ether intermediate is prepared through ring-opening polymerization reaction; the dosage of the three raw materials is n(Et 2 O·BF 3 ):n(ECH):n(HPEG)=0.04:1.25:1 (molar ratio). The dropping time of ECH is 0.5 h. After dropping, continue the heat preservation reaction for 2 h and then cool down, and remove the excessive ECH through vacuum distillation to obtain the finished product methyl allyl polyoxyethylene epichlorohydrin ether intermediate;

[0074] S2. Then continue to adopt the base-catalysis method, using dihydroeugenol and methyl allyl polyoxyethylene epichlorohydrin ether intermediate as the main raw materials. After adding them into the reaction vessel according to the molar ratio of 1:1, use NaOH solution to adjust the pH value to 13, and react at 80 °C for 3 h to obtain the dihydroeugenol-grafted polyether macromonomer (D-HPEG).

[0075] In some embodiments, the preparation of the anti-sludge viscosity-reducing water reducer (DPCE) includes the following steps:

[0076] First, using allyl polyoxyethylene ether macromonomer (HPEG, Mx = 2400) and acrylic acid (AA) as the main raw materials, with an acid-ether ratio of 4:1 (molar ratio), a common water-reducing polycarboxylate superplasticizer (PCE-S) is synthesized through free radical copolymerization reaction; secondly, using dihydroeugenol grafted polyether macromonomer (D-HPEG) to replace HPEG equivalently at 20% - 25%, a new type of anti-sludge viscosity-reducing polycarboxylate water reducer (DPCE) is synthesized.

[0077] In some embodiments, the viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture includes a mixture of mineral powder, fly ash microspheres, silica fume, and C 4 AF.

[0078] Among them, the mass ratio of mineral powder, fly ash microspheres, silica fume, and C 4 AF is (10 - 30):(10 - 40):(10 - 40):(10 - 50).

[0079] In some embodiments, the specific surface area of the mineral powder is 300 - 900m 2 / kg.

[0080] In some embodiments, the SiO 2 mass content of silica fume is ≥95%, the specific surface area is ≥15500m 2 / kg, and the 28-day activity index is ≥100%.

[0081] In some embodiments, the calcination temperature of C 4 AF (i.e., tetracalcium ferroaluminate) is 1340 - 1390°C, its specific surface area is 350 - 500m 2 / kg, and the aluminum doping content is 17 - 20%.

[0082] In some embodiments, the multi-scale hybrid fibers include a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic fumed nano-SiO 2 particles. Among them, the mass ratio of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic fumed nano-SiO 2 particles is 100:(0 - 40):(0 - 30):(0 - 10).

[0083] In some embodiments, the nominal length of the copper-plated steel fibers is 6 - 13mm, the equivalent diameter is 0.10 - 0.20mm, the fracture strength is ≥2000MPa, and the elastic modulus is 160 - 220Gpa.

[0084] In some embodiments, the nominal length of the multi-anchor steel fiber is 10 - 16 mm, the equivalent diameter is 0.18 - 0.25 mm, the fracture strength is ≥1000 MPa, and the elastic modulus is 210 - 230 GPa.

[0085] In some embodiments, the nominal length of the temperature-shrinkable organic fiber is 6 - 12 mm, the equivalent diameter is 0.10 - 0.20 mm, the fracture strength is ≥550 MPa, and the elastic modulus is ≥8 GPa.

[0086] In some embodiments, the hydrophilic fumed nano-SiO 2 particles are of the Hydrophillic-380 type, and the specific surface area is ≥380 m 2 / g.

[0087] In some embodiments, the cement is P·II 52.5 Portland cement.

[0088] In some embodiments, the expansive agent is azodicarbonamide expansive agent.

[0089] In some embodiments, the mullite sand is a porous aggregate with a saturated surface dry water absorption rate of 1% - 8%, a particle size of 20 - 40 mm, and an apparent density of 2300 - 2600 kg / m 3 .

[0090] In some embodiments, the basalt coarse aggregate has a water absorption rate of 1% - 5% and is a high-strength aggregate with a continuous gradation of 5 - 16 mm. The apparent density of the basalt coarse aggregate is 2800 - 3100 kg / m 3 .

[0091] In some embodiments, the special super-dispersing viscosity-reducing admixture further includes an ionic adsorption-dispersing defoaming agent, a viscosity modifier (VMA), and a retarder (HNJ).

[0092] In some embodiments, the mass ratio of the air-entraining water reducer, the anti-sludge viscosity-reducing water reducer, the ionic adsorption-dispersing defoaming agent, the viscosity modifier, and the retarder in the special super-dispersing viscosity-reducing admixture is 1:(0.6 - 1.2):(0.1 - 0.5):(0.03 - 0.07):(0.02 - 0.06).

[0093] Among them, the defoaming agent is an ionic adsorption-dispersing defoaming agent, which can ionize positive ions and negative ions after dissolving in water. These ions adsorb on the surface of colloidal particles with opposite charges, and then a double electric layer is formed on the ion surface, resulting in an increase in the zeta potential. Organic silicon-based, polyether-based, etc. can be selected; the viscosity modifier can be selected from polyacrylamide, cellulose ether, polyvinyl alcohol, xanthan gum, etc.; the retarder can be selected from sodium gluconate, polyphosphoric acid, sodium citrate, etc.

[0094] In some embodiments, the ionic adsorption dispersion defoamer used is acrylic acid modified silicone. Its acrylic acid functional groups can adsorb cement mineral admixture particles, and the silicone can reduce the surface tension and trigger the uniform dispersion of different cementitious material particles.

[0095] Based on the same inventive concept, the present invention also provides a preparation method of the above-mentioned high-fluidity, low-shrinkage and high-toughness fiber concrete, comprising the following steps:

[0096] S1. Mix cement, viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture, expansive agent, mullite sand and basalt coarse aggregate, then stir, add water and super-dispersing viscosity-reducing special additive, continue to stir, then add multi-scale hybrid fibers, mold, vibrate and form, and cover the surface with an impermeable film for film curing;

[0097] S2. After demolding, perform standard curing to obtain the high-fluidity, low-shrinkage and high-toughness fiber concrete.

[0098] Specifically, mix cement, viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture, expansive agent, mullite sand and basalt coarse aggregate in a mixer for 1 - 2 min, then add water and super-dispersing viscosity-reducing special additive, continue to stir for 5 - 10 min, then add multi-scale hybrid fibers, mold, vibrate and form, and cover the surface with an impermeable film for film curing; after demolding, perform standard curing for 28 d to obtain the high-fluidity, low-shrinkage and high-toughness fiber concrete.

[0099] The principle adopted by the present invention is as follows:

[0100] 1. The present invention incorporates multi-scale hybrid fibers and realizes the high-toughness design of fiber concrete through toughening design of concrete at multiple scales of macro, micron, nano and molecule. Specifically, it is manifested as follows: using copper-plated steel fibers and multi-anchor steel fibers in hybrid to improve the interfacial transition zone of traditional concrete and enhance the toughness of concrete at the macro scale; by adding temperature-shrinkage type fibers and utilizing the characteristic of generating pre-compressive stress due to their temperature rise and shrinkage, enhancing the toughness of concrete at the micron scale; by introducing gas-phase nano-SiO 2 and further improving the toughness and mechanical properties of concrete at the nano scale through the small-scale effect; in addition, by adjusting the dosage of viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture and the proportion of C 4 AF components therein, regulating the composition of C-S-H gel in fiber concrete to form high-aluminum doped C-A-S-H gel and enhancing the toughness of fiber concrete at the molecular scale;

[0101] 2. The present invention realizes the high-modulus design of fiber concrete by incorporating high-modulus mullite sand and basalt coarse aggregate. Compared with ordinary quartz sand, machine-made sand and river sand, mullite sand has the characteristics of high strength and high elastic modulus, and can well improve the mechanical properties and elastic modulus of high-toughness fiber concrete.

[0102] 3. Using the super-dispersed viscosity-reducing special admixture prepared by the present invention as an admixture can effectively eliminate the number of large air bubbles in fiber concrete, increase the compactness of the paste, and at the same time introduce a large number of small-sized air bubbles into the concrete through the air-entraining component therein, effectively improving the fluidity of fiber concrete; meanwhile, the "ball-bearing" effect of the fly ash microsphere component in the viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture can also effectively improve the workability of fiber concrete. The synergistic effect of the super-dispersed viscosity-reducing special admixture and the viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture realizes the high-fluidity design of fiber concrete.

[0103] 4. In addition, the porous-structured mullite sand and basalt coarse aggregate have an internal curing effect in the cementitious paste after being saturated and pre-wetted with water, which can relieve the self-drying effect of the cement stone matrix, reduce the shrinkage of fiber concrete, and improve its volume stability and crack resistance; in addition, the compensating shrinkage effect of the azodicarbonamide expander further improves the volume stability of fiber concrete, realizing the low-shrinkage design of fiber concrete.

[0104] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0105] 1. Utilize the "ball-bearing" effect of fly ash microspheres in the viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture and the viscosity-reducing effect of the super-dispersed viscosity-reducing special admixture to optimize the workability of the concrete mixture, improve the compactness and homogeneity of the concrete, and realize the self-compacting and high-fluidity design of high-strength concrete.

[0106] 2. Synergistically improve the toughness of fiber concrete at multiple scales: Utilize the small-scale effect of gas-phase nano-SiO 2 particles to achieve toughness enhancement design of fiber concrete at the molecular scale; C 4 AF components release a large amount of Al during the early hydration stage, enter the C-S-H gel to form a large amount of C-(A)-S-H gel, increase the chain length of the Si-O chain in the gel, and effectively improve the toughness of fiber concrete at the molecular scale; utilize the characteristics of the temperature-shrinking fiber to shrink at high temperature and apply pre-compressive stress to achieve toughness enhancement of the concrete at the micron scale; at the same time, adding copper-plated steel fibers and multi-anchor steel fibers to the concrete realizes toughness enhancement of the concrete at the macroscopic scale.

[0107] 3. Using high-modulus mullite sand and basalt coarse aggregate, high-modulus fiber concrete with an elastic modulus ≥ 45 GPa can be prepared when the compressive strength grade is C80 - C100 through the dense packing design principle.

[0108] 4. By utilizing the internal curing effect of mullite sand and basalt coarse aggregate, and combining with the compensating shrinkage of azodicarbonamide expander, the problem of large shrinkage of high-strength fiber concrete is improved to a certain extent. At the same time, the pre-mixing process is combined to promote the formation of a high-strength and dense C-S-H gel interfacial transition zone around the mullite sand, reduce the porosity, solve the defect problem between the paste and the interface, and improve the mechanical properties and durability of high-fluidity, high-elastic modulus, high-toughness and low-shrinkage fiber concrete.

[0109] The apparent density of the high-fluidity, high-elastic modulus, high-toughness and low-shrinkage fiber concrete obtained by the present invention is 2300-2600 kg / m 3 , and at the same time, the compressive strength grade can reach above C80, and it has good workability, mechanical properties and volume stability, can effectively improve the toughness, elastic modulus and durability of concrete components, and has important practical application value.

[0110] The following further illustrates the high-fluidity, low-shrinkage and high-toughness fiber concrete of the present application, its preparation method, concrete admixtures and applications with specific examples. This part further illustrates the content of the present invention with specific examples, but should not be construed as a limitation of the present invention. Unless otherwise specified, the technical means adopted in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0111] In the following examples, the cement is Huaxin P·II 52.5 ordinary Portland cement; the expander is azodicarbonamide expander; the viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture is a mixture of ultrafine mineral powder, fly ash microspheres, silica fume and high-activity C 4 AF in proportion, where the specific surface area of the ultrafine mineral powder is 300-900 m 2 / kg; the SiO 2 mass content of silica fume is ≥95%, the specific surface area is ≥15500 m 2 / kg, and the 28-day activity index is ≥100%; the calcination temperature of C 4 AF is 1340-1390 °C, and its specific surface area is 350-500 m 2 / kg, with an aluminum doping content of 17 - 20%; the multi-scale hybrid fibers are composed of a mixture of various fibers. Among them, the copper-plated steel fibers and multi-anchor steel fibers are both produced by Wuhan Xintu Engineering New Materials Technology Co., Ltd. The nominal length of the copper-plated steel fibers is 13 mm, the equivalent diameter is 0.20 mm, the fracture strength is ≥2000 MPa, and the elastic modulus is 200 - 220 GPa; the nominal length of the multi-anchor steel fibers is 16 mm, the equivalent diameter is 0.25 mm, the fracture strength is ≥1000 MPa, and the elastic modulus is 210 - 230 GPa. The nominal length is 13 mm, the equivalent diameter is 0.22 mm, the fracture strength is about 3500 MPa, and the elastic modulus is about 52 GPa; the temperature-shrinking organic fibers (specifically polypropylene fibers) have a nominal length of 6 - 12 mm, an equivalent diameter of 0.10 - 0.20 mm, a fracture strength of ≥550 MPa, and an elastic modulus of ≥8 GPa; the hydrophilic gas-phase nano-SiO 2 particles are of the Hydrophillic-380 type, with a specific surface area of ≥380 m 2 / g; the water is ordinary tap water.

[0112] In the following examples, the preparation method of the air-entraining water reducer (DAFS) includes the following steps:

[0113] Add liquid sodium hydroxide to water in a four-necked flask equipped with a stirrer, a condenser, and a thermometer. After making the pH value of the base material strongly alkaline (pH = 12), add sodium metabisulfite to dissolve it to obtain a saturated solution of sodium bisulfite. Under the condition of a temperature of 50 °C, dropwise add acetone for sulfonation for 1 h to generate sodium α-olefin sulfonate through the sulfonation reaction. After the sulfonation reaction ends, keep the temperature unchanged and dropwise add formaldehyde for 3 h, then add dihydroeugenol and an auxiliary agent. After dropping formaldehyde, raise the temperature to 97 ± 2 °C for condensation for 2.5 h. Finally, cool the reactant to room temperature, and add an appropriate amount (a foaming stabilizer of 0.3% of the mass of dihydroeugenol) of a foaming stabilizer (specifically cellulose ether) to obtain the air-entraining water reducer (DAFS); among them, the mass ratio of dihydroeugenol, sodium metabisulfite, acetone, formaldehyde, and the auxiliary agent (provided by Wuhan Subo New Building Materials Co., Ltd., model AM01) is 12:38:50:136:2.

[0114] In the following examples, the preparation method of the anti-sludge viscosity-reducing water reducer (DPCE) includes the following steps:

[0115] S1. First, adopt the acid-catalysis method. Using epichlorohydrin (ECH) and allyl polyoxyethylene ether (HPEG, Mx = 2400) as the main raw materials, after heating and melting HPEG, use the common boron trifluoride diethyl ether (Et 2 O·BF 3)As a catalyst, keep adding ECH dropwise at a constant speed of 60 °C, and prepare the intermediate of methyl allyl polyoxyethylene epichlorohydrin ether through ring-opening polymerization reaction; the amounts of the three raw materials are n(Et 2 O·BF 3 ): n(ECH): n(HPEG) = 0.04: 1.25: 1 (molar ratio). The dropping time of ECH is 0.5 h. After dropping, keep the temperature for reaction for another 2 h and then cool down. Remove the excessive ECH by vacuum distillation to obtain the finished product of the intermediate of methyl allyl polyoxyethylene epichlorohydrin ether;

[0116] S2. Continue to adopt the base-catalyzed method. Using dihydroeugenol and the intermediate of methyl allyl polyoxyethylene epichlorohydrin ether as the main raw materials, after adding them into the reaction vessel in a molar ratio of 1:1, use the NaOH solution to adjust the pH value to 13, and react at 80 °C for 3 h to obtain the dihydroeugenol-grafted polyether macromonomer (D-HPEG);

[0117] S3. Using the dihydroeugenol-grafted polyether macromonomer (D-HPEG) and acrylic acid (AA) as raw materials, synthesize the anti-sludge viscosity-reducing water reducer (DPCE) through free radical copolymerization reaction; the molar ratio of acrylic acid (AA) to the dihydroeugenol-grafted polyether macromonomer (D-HPEG) is 4:1.

[0118] Figure 2 This is the infrared spectrum (IR) diagram of the air-entraining water reducer (DAFS) prepared by the present invention.

[0119] Figure 2 In the infrared spectrum (IR) shown, at 3448 cm -1 is the characteristic absorption peak of hydroxyl (-OH), at 2931 cm -1 is the characteristic absorption peak of methylene (-CH 2 -), at 1643 cm -1 the strong absorption peak is the characteristic adsorption peak of carbonyl (C=O), and at 1188 cm -1 and 1041 cm -1 are the stretching peaks of S-O and S=O with sulfonic acid groups, which are several typical characteristic peaks of the molecule of sulfonated acetone formaldehyde condensate (AFS). Compared with AFS, the characteristic absorption peak of hydroxyl (-OH) of the polymer obtained by grafting the air-entraining water reducer (DAFS) is significantly weakened, which is related to the disappearance of hydroxyl during the dehydration condensation of phenolic compounds and dihydroxyacetone. In addition, DAFS has a relatively strong characteristic absorption peak of benzene ring at 1585 cm -1 , indicating that dihydroeugenol containing benzene ring functional groups is grafted onto the molecular chain of AFS through chemical reaction.

[0120] Figure 3 This is the nuclear magnetic resonance hydrogen spectrum ( 11H NMR spectrum

[0121] In Figure 3 the nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) shown, there are significantly new characteristic nuclear magnetic absorption peaks of benzene ring H atoms at the chemical shift δ = 6.55 - 6.73 of DAFS. And due to the polycondensation of the alkyl chain to the AFS molecular chain through formaldehyde, the characteristic peak intensities corresponding to CH 3 and CH 2 near δ = 1.22 and 1.82 of several grafted products are significantly enhanced, further indicating that dihydroeugenol containing benzene ring functional groups is grafted onto the main chain of the AFS molecule through chemical reactions.

[0122] Figure 4 This is the infrared spectrum (IR) of the anti-sludge viscosity-reducing water reducer (DPCE) prepared in the present invention.

[0123] Figure 4 The infrared spectrum (IR) characterization results shown indicate that compared with the polycarboxylate water reducer (PCE-S) synthesized without adding dihydroeugenol, the prepared anti-sludge viscosity-reducing polycarboxylate water reducer DPCE has new characteristic absorption peaks of benzene ring at 1600 cm -1 and 1510 cm -1 etc. It shows that the modified polyether D-HPEG synthesized from dihydroeugenol has been successfully grafted onto the DPCE molecular chain.

[0124] Figure 5 This is the nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) of the anti-sludge viscosity-reducing water reducer (DPCE) prepared in the present invention.

[0125] Figure 5 In the nuclear magnetic resonance hydrogen spectrum ( 1 1H NMR) characterization results shown, DPCE has new characteristic nuclear magnetic absorption peaks of benzene ring H atoms at the chemical shift δ = 6.81 - 6.93 compared with PCE-S, which is consistent with the infrared spectrum characterization results, further indicating that the modified polyether D-HPEG synthesized from dihydroeugenol has been successfully grafted onto the DPCE molecular chain.

[0126] Example 1

[0127] This embodiment of the present application provides a high-fluidity, low-shrinkage, and high-toughness fiber concrete, including the following raw materials: cement 480 kg / m 3 , viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture 185 kg / m 3 , mullite sand 840 kg / m 3 , basalt coarse aggregate 1100 kg / m 3 , multi-scale hybrid fiber 41 kg / m 3 , super-dispersing viscosity-reducing special admixture 10 kg / m3 , expansive agent 10 kg / m 3 , water 141 kg / m 3 ;

[0128] Among them, the viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture includes a mixture of mineral powder, fly ash microspheres, silica fume and C 4 AF; the mass ratio of mineral powder, fly ash microspheres, silica fume and C 4 AF is 20:30:30:20;

[0129] The multi-scale hybrid fibers include a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers and hydrophilic gas-phase nano-SiO 2 particles;

[0130] Among them, the mass ratio of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers and hydrophilic gas-phase nano-SiO 2 particles is 80:20:10:1;

[0131] The super-dispersed viscosity-reducing special admixture includes a mixture of air-entraining water reducer, anti-sludge viscosity-reducing water reducer, defoamer, viscosity modifier and retarder; among them, the defoamer is acrylic-modified silicone, the viscosity modifier is xanthan gum, and the retarder is sodium citrate;

[0132] The mass ratio of air-entraining water reducer, anti-sludge viscosity-reducing water reducer, defoamer, viscosity modifier and retarder is 1:0.65:0.004:0.006:0.012;

[0133] The preparation method of the above-mentioned high-fluidity, low-shrinkage and high-toughness fiber concrete includes the following steps:

[0134] S1. Soak mullite sand (840 kg / m 3 ) and basalt coarse aggregate (1100 kg / m 3 ) in water until saturated;

[0135] S2. Mix the saturated mullite sand, saturated basalt coarse aggregate, cement (480 kg / m 3 ), viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture (185 kg / m 3 ), expansive agent (10 kg / m 3 ) in a mixing pan for 2 min, then add water (141 kg / m 3 ) and super-dispersed viscosity-reducing special admixture (10 kg / m 3 ), continue to mix for 8 min, then add multi-scale hybrid fibers (41 kg / m 3 ), mold, vibrate and form, cover the surface with an impermeable film for film curing; after demolding, carry out standard curing for 28 d to obtain high-fluidity, low-shrinkage and high-toughness fiber concrete.

[0136] Example 2

[0137] An embodiment of the present application provides a high-fluidity, low-shrinkage, and high-toughness fiber concrete, comprising the following raw materials: 520 kg / m of cement 3 , 160 kg / m of viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture 3 , 900 kg / m of mullite sand 3 , 1000 kg / m of basalt coarse aggregate 3 , 41 kg / m of multi-scale hybrid fiber 3 , 10 kg / m of super-dispersing viscosity-reducing special admixture 3 , 10 kg / m of expansive agent 3 , 141 kg / m of water 3 ;

[0138] Among them, the viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture includes a mixture of mineral powder, fly ash microspheres, silica fume, and C 4 AF; the mass ratio of mineral powder, fly ash microspheres, silica fume, and C 4 AF is 20:30:30:20;

[0139] The multi-scale hybrid fiber includes a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic gas-phase nano-SiO 2 particles;

[0140] Among them, the mass ratio of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic gas-phase nano-SiO 2 particles is 80:20:10:1;

[0141] The super-dispersing viscosity-reducing special admixture includes a mixture of an air-entraining water reducer, an anti-sludge viscosity-reducing water reducer, a defoaming agent, a viscosity modifier, and a retarder; among them, the defoaming agent is acrylic acid-modified silicone, the viscosity modifier is xanthan gum, and the retarder is sodium citrate;

[0142] The mass ratio of the air-entraining water reducer, the anti-sludge viscosity-reducing water reducer, the defoaming agent, the viscosity modifier, and the retarder is 1:0.65:0.004:0.006:0.012;

[0143] The preparation method of the above high-fluidity, low-shrinkage, and high-toughness fiber concrete comprises the following steps:

[0144] S1. Soak mullite sand (900 kg / m 3 ) and basalt coarse aggregate (1000 kg / m 3 ) in water until they reach a saturated water state;

[0145] S2. The saturated mullite sand, the saturated basalt coarse aggregate, and cement (520 kg / m3 ) The viscosity-reducing, strength-increasing and toughness-enhancing mineral admixture (160 kg / m 3 ), the expansive agent (10 kg / m 3 ) are stirred in a mixing pan for 2 min, then water (141 kg / m 3 ) and the special super-dispersing viscosity-reducing admixture (10 kg / m 3 ) are added, and stirring continues for 8 min. Then multi-scale hybrid fibers (41 kg / m 3 ) are added, and it is put into a mold, vibrated and formed, and the surface is covered with an impermeable film for film curing; after demolding, standard curing is carried out for 28 d to obtain high-fluidity, low-shrinkage and high-toughness fiber concrete.

[0146] Comparative Example 1

[0147] This comparative example provides a fiber concrete, including the following raw materials: cement 480 kg / m 3 , viscosity-reducing, strength-increasing and toughness-enhancing mineral admixture 185 kg / m 3 , quartz sand 840 kg / m 3 , crushed stone 1100 kg / m 3 , multi-scale hybrid fibers 41 kg / m 3 , special super-dispersing viscosity-reducing admixture 10 kg / m 3 , expansive agent 0 kg / m 3 , water 141 kg / m 3 ;

[0148] Among them, the viscosity-reducing, strength-increasing and toughness-enhancing mineral admixture includes a mixture of mineral powder, fly ash microspheres, silica fume and C 4 AF; the mass ratio of mineral powder, fly ash microspheres, silica fume and C 4 AF is 20:30:30:20;

[0149] The multi-scale hybrid fibers include a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkage organic fibers and hydrophilic gas-phase nano-SiO 2 particles;

[0150] Among them, the mass ratio of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkage organic fibers and hydrophilic gas-phase nano-SiO 2 particles is 80:20:10:1;

[0151] The special super-dispersing viscosity-reducing admixture includes a mixture of an air-entraining water reducer, an anti-sludge viscosity-reducing water reducer, an antifoaming agent, a viscosity modifier and a retarder; among them, the antifoaming agent is acrylic acid-modified silicone, the viscosity modifier is xanthan gum, and the retarder is sodium citrate;

[0152] The mass ratio of the air-entraining water reducer, anti-sludge viscosity-reducing water reducer, defoamer, viscosity modifier, and retarder is 1:0.65:0.004:0.006:0.012;

[0153] The preparation method of the above fiber concrete includes the following steps:

[0154] S1. Immerse the quartz sand (840 kg / m 3 ) in water until it reaches a saturated water state;

[0155] S2. Stir the saturated quartz sand, crushed stone (1100 kg / m 3 ), cement (480 kg / m 3 ), viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture (185 kg / m 3 ) in a mixing pan for 2 min, then add water (141 kg / m 3 ) and super-dispersing viscosity-reducing special admixture (10 kg / m 3 ), continue stirring for 8 min, then add multi-scale hybrid fibers (41 kg / m 3 ), mold, vibrate, and form. Cover the surface with an impermeable film for film curing; after demolding, conduct standard curing for 28 d to obtain the fiber concrete.

[0156] Comparative Example 2

[0157] This comparative example provides a fiber concrete, including the following raw materials: cement 480 kg / m 3 , viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture 185 kg / m 3 , quartz sand 840 kg / m 3 , crushed stone 1100 kg / m 3 , multi-scale hybrid fibers 41 kg / m 3 , super-dispersing viscosity-reducing special admixture 10 kg / m 3 , expansive agent 10 kg / m 3 , water 141 kg / m 3 ;

[0158] Among them, the viscosity-reducing, strength-enhancing, and toughness-enhancing mineral admixture includes a mixture of mineral powder, fly ash microspheres, silica fume, and C 4 AF; the mass ratio of mineral powder, fly ash microspheres, silica fume, and C 4 AF is 20:30:30:20;

[0159] The multi-scale hybrid fibers include a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic fumed nano-SiO 2 particles;

[0160] Among them, the copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic fumed nano-SiO2 The mass ratio of the particles is 80:20:10:1;

[0161] The special super-dispersing viscosity-reducing admixture includes a mixture of an air-entraining water reducer, an anti-sludge viscosity-reducing water reducer, an antifoaming agent, a viscosity modifier, and a retarder; among them, the antifoaming agent is acrylic acid-modified silicone, the viscosity modifier is xanthan gum, and the retarder is sodium citrate;

[0162] The mass ratio of the air-entraining water reducer, the anti-sludge viscosity-reducing water reducer, the antifoaming agent, the viscosity modifier, and the retarder is 1:0.65:0.004:0.006:0.012;

[0163] The preparation method of the above fiber concrete includes the following steps:

[0164] S1. Soak the quartz sand (840 kg / m 3 ) in water until it reaches a saturated water state;

[0165] S2. Put the saturated quartz sand, crushed stone (1100 kg / m 3 ), cement (480 kg / m 3 ), viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture (185 kg / m 3 ), and expansion agent (10 kg / m 3 ) into the mixing pot and stir for 2 min, then add water (141 kg / m 3 ) and the special super-dispersing viscosity-reducing admixture (10 kg / m 3 ), continue to stir for 8 min, then add multi-scale hybrid fibers (41 kg / m 3 ), mold, vibrate, and form, cover the surface with an impermeable film for film curing; after demolding, conduct standard curing for 28 d to obtain the fiber concrete.

[0166] Comparative Example 3

[0167] This comparative example provides a fiber concrete, including the following raw materials: cement 480 kg / m 3 , viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture 185 kg / m 3 , mullite sand 840 kg / m 3 , basalt coarse aggregate 1100 kg / m 3 , multi-scale hybrid fibers 41 kg / m 3 , ordinary water reducer (specifically polycarboxylate water reducer) 10 kg / m 3 , expansion agent 10 kg / m 3 , water 141 kg / m 3 ;

[0168] Among them, the viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture includes mineral powder, fly ash microspheres, silica fume, and C 4Mixture of AF; Mineral powder, fly ash microspheres, silica fume and C 4 The mass ratio of AF is 20:30:30:20;

[0169] The multi-scale hybrid fibers include a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers and hydrophilic fumed nano-SiO 2 particles;

[0170] Among them, the mass ratio of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers and hydrophilic fumed nano-SiO 2 particles is 80:20:10:1;

[0171] The preparation method of the above fiber concrete includes the following steps:

[0172] S1. Immerse mullite sand (840 kg / m 3 ) and basalt coarse aggregate (1100 kg / m 3 ) in water until saturated;

[0173] S2. Put the saturated mullite sand, saturated basalt coarse aggregate, cement (480 kg / m 3 ), viscosity-reducing, strength-enhancing and toughness-enhancing mineral admixture (185 kg / m 3 ), expansive agent (10 kg / m 3 ) into the mixing pot and stir for 2 min, then add water (141 kg / m 3 ) and ordinary water reducer (10 kg / m 3 ), continue to stir for 8 min, then add multi-scale hybrid fibers (41 kg / m 3 ), mold, vibrate and form, cover the surface with an impermeable film for film curing; after demolding, carry out standard curing for 28 d to obtain fiber concrete.

[0174] Comparative Example 4

[0175] This comparative example provides a fiber concrete, including the following raw materials: cement 480 kg / m 3 , silica fume 95 kg / m 3 , fly ash microspheres 90 kg / m 3 , mullite sand 840 kg / m 3 , basalt coarse aggregate 1100 kg / m 3 , steel fibers 60 kg / m 3 , super-dispersed viscosity-reducing special admixture 10 kg / m 3 , expansive agent 10 kg / m 3 , water 141 kg / m 3 ;

[0176] The special admixture for super-dispersion viscosity reduction includes a mixture of an air-entraining water reducer, an anti-sludge viscosity-reducing water reducer, a defoamer, a viscosity modifier, and a retarder; among them, the defoamer is acrylic-modified silicone, the viscosity modifier is xanthan gum, and the retarder is sodium citrate;

[0177] The mass ratio of the air-entraining water reducer, the anti-sludge viscosity-reducing water reducer, the defoamer, the viscosity modifier, and the retarder is 1:0.65:0.004:0.006:0.012;

[0178] The preparation method of the above fiber concrete includes the following steps:

[0179] S1. Immerse both mullite sand (840 kg / m 3 ) and basalt coarse aggregate (1100 kg / m 3 ) in water until they reach a saturated water state;

[0180] S2. Stir the saturated mullite sand, the saturated basalt coarse aggregate, cement (480 kg / m 3 ), silica fume (95 kg / m 3 ), fly ash microspheres (90 kg / m 3 ), and expansive agent (10 kg / m 3 ) in a mixing pot for 2 min, then add water (141 kg / m 3 ) and the special admixture for super-dispersion viscosity reduction (10 kg / m 3 ), continue to stir for 8 min, then add steel fibers (60 kg / m 3 ), mold, vibrate, and form. Cover the surface with an impermeable film for film curing; after demolding, conduct standard curing for 28 d to obtain the fiber concrete.

[0181] Performance testing

[0182] Test the performance of the high-fluidity, low-shrinkage, and high-toughness fiber concrete in Test Examples 1-2 and the fiber concrete in Comparative Examples 1-4. The results are shown in Table 1 below.

[0183] Table 1 - Performance of fiber concrete in different examples

[0184]

[0185] The above results show that the high-fluidity, high-elastic modulus, high-toughness and low-shrinkage fiber concrete obtained by the present invention has good workability, mechanical properties and volume stability, and the compressive strength of the obtained high-fluidity, high-elastic modulus, high-toughness and low-shrinkage fiber concrete is above 90 MPa. In addition, by comparing Example 1 with Comparative Example 1, it is found that the use of internal curing aggregates (mullite sand) and expansive agents can effectively reduce the shrinkage and creep properties of concrete; by comparing Example 1 with Comparative Examples 1-2, it is found that the incorporation of high-modulus mullite sand and basalt coarse aggregates can effectively improve the elastic modulus and mechanical properties of concrete; by comparing Example 1 with Comparative Example 3, it is found that the incorporation of a special super-dispersing viscosity-reducing admixture can significantly improve the fluidity of concrete; by comparing Example 1 with Comparative Example 4, it is found that the introduction of multi-scale hybrid fibers and C 4 AF can effectively improve the flexural toughness of concrete.

[0186] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-fluidity, low-shrinkage, and high-toughness fiber concrete, characterized in that, it comprises the following raw materials: Cement: 400 - 550 kg / m 3 , viscosity-reducing, strength-increasing and toughness-increasing mineral admixture: 100 - 300 kg / m 3 , mullite sand: 600 - 900 kg / m 3 , basalt coarse aggregate: 1000 - 1200 kg / m 3 , multi-scale hybrid fiber: 10 - 100 kg / m 3 , special super-dispersing viscosity-reducing admixture: 6 - 10 kg / m 3 , expansive agent: 5 - 25 kg / m 3 , water: 120 - 180 kg / m 3 ; The super-dispersion viscosity-reducing special admixture is a mixture of an air-entraining water reducer, an anti-sludge viscosity-reducing water reducer, an antifoaming agent, a viscosity modifier, and a retarder; The viscosity-reducing, strength-enhancing and toughness-increasing mineral admixture includes mineral powder, fly ash microspheres, silica fume and a mixture of C 4 AF; The multi-scale hybrid fibers include a mixture of copper-plated steel fibers, multi-anchor steel fibers, temperature-shrinkable organic fibers, and hydrophilic fumed nano-SiO 2 particles; the temperature-shrinkable organic fibers are polypropylene fibers; The structural formula of the air-entraining water reducer is as follows: ； wherein, x is a positive integer between 30 and 80, and y is a positive integer between 20 and 70; The structural formula of the anti-sludge viscosity-reducing water reducer is as follows: ； wherein, a is a positive integer between 5 and 20, b is a positive integer between 20 and 100, c is a positive integer between 1 and 5, and n is a positive integer between 25 and 55.

2. The high-fluidity, low-shrinkage, and high-toughness fiber concrete according to claim 1, characterized in that, the preparation method of the air-entraining water reducer comprises the following steps: Adding sodium metabisulfite and liquid caustic soda into water for reaction to obtain a sodium bisulfite solution; Adding acetone, dihydroeugenol, and an auxiliary agent into the sodium bisulfite solution, and the sodium bisulfite and acetone undergo a sulfonation reaction to generate α-olefin sulfonate; After the sulfonation reaction ends, adding formaldehyde for a condensation reaction, and adding a foam stabilizer after the condensation reaction is completed to obtain the air-entraining water reducer.

3. The high-fluidity, low-shrinkage, and high-toughness fiber concrete according to claim 1, characterized in that, the preparation method of the anti-sludge viscosity-reducing water reducer comprises the following steps: Using epichlorohydrin and allyl polyoxyethylene ether as raw materials, and preparing an allyl polyoxyethylene chlorohydrin ether intermediate through a ring-opening polymerization reaction; Using dihydroeugenol and the allyl polyoxyethylene chlorohydrin ether intermediate as raw materials to prepare a dihydroeugenol-grafted polyether macromonomer; Using the dihydroeugenol-grafted polyether macromonomer, allyl polyoxyethylene ether, and acrylic acid as raw materials to prepare the anti-sludge viscosity-reducing water reducer.

4. The high-fluidity, low-shrinkage, and high-toughness fiber concrete according to claim 1, characterized in that, The specific surface area of the mineral powder is 300 - 900 m 2 / kg; the SiO 2 mass content of silica fume is ≥ 95%, the specific surface area is ≥ 15500 m 2 / kg, and the 28-day activity index is ≥ 100%; the calcination temperature of C 4 AF is 1340 - 1390 °C, its specific surface area is 350 - 500 m 2 / kg, and the aluminum doping content is 17 - 20%.

5. The high-fluidity, low-shrinkage, and high-toughness fiber concrete according to claim 1, characterized in that, The mass ratio of the copper-plated steel fiber, multi-anchor steel fiber, temperature-shrinkable organic fiber and hydrophilic fumed nano-SiO 2 particles is 100:(0~40):(0~30):(0~10).

6. The high-fluidity, low-shrinkage, and high-toughness fiber concrete according to claim 1, characterized in that, The nominal length of the copper-plated steel fiber is 6 to 13 mm, the equivalent diameter is 0.10 to 0.20 mm, the fracture strength is ≥2000 MPa, and the elastic modulus is 160 to 220 GPa; the nominal length of the multi-anchor steel fiber is 10 to 16 mm, the equivalent diameter is 0.18 to 0.25 mm, the fracture strength is ≥1000 MPa, and the elastic modulus is 210 to 230 GPa; the nominal length of the temperature-shrinkable organic fiber is 6 to 12 mm, the equivalent diameter is 0.10 to 0.20 mm, the fracture strength is ≥550 MPa, and the elastic modulus is ≥8 GPa; the hydrophilic fumed nano-SiO 2 The specific surface area of the particles is ≥380 m 2 / g.

7. The high-fluidity, low-shrinkage, and high-toughness fiber concrete according to claim 1, characterized in that, the cement is P•II52.5 Portland cement; the expansive agent is azodicarbonamide expansive agent; The saturated surface dry water absorption rate of the mullite sand is 1% - 8%, the particle size is 20 - 40 mm, and the apparent density is 2300 - 2600 kg / m 3 ; the water absorption rate of the basalt coarse aggregate is 1% - 5%; The basalt coarse aggregate is a high-strength aggregate with a continuous grading of 5 - 16 mm, and the apparent density of the basalt coarse aggregate is 2800 - 3100 kg / m 3 .

8. A preparation method of the high-fluidity, low-shrinkage, and high-toughness fiber concrete according to any one of claims 1 to 7, characterized in that, it comprises the following steps: Mixing cement, viscosity-reducing, strength-increasing, and toughness-increasing mineral admixture, expansive agent, mullite sand, and basalt coarse aggregate, then stirring, adding water and the super-dispersion viscosity-reducing special admixture, continuing to stir, then adding multi-scale hybrid fibers, molding in a mold, vibrating, and forming, covering the surface with an impermeable film for film curing; After demolding, perform standard curing to obtain the high-fluidity, low-shrinkage, and high-toughness fiber concrete.

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