A seawater erosion-resistant ferroaluminate cement concrete and its preparation method

Abstract

The present invention relates to the technical field of building materials, and discloses a seawater-resistant calcium ferrite cement concrete and a preparation method thereof, which are obtained by using bis[3-(trimethoxysilyl)propyl]amine, perfluorohexylethylene, and 3-bromopropene as raw materials, through addition and quaternization reactions, polymerizing with acrylic monomers, and then compounding with calcium ferrite cement, composite steel slag powder, and modified basalt fibers, etc.; the fluorinated quaternary ammonium salt siloxane modifier has relatively rich siloxane bond functional groups on the surface of the siloxane, which can undergo a condensation reaction with the silanol groups on the surface of the concrete substrate after hydrolysis, effectively filling the pores and cracks in the concrete material; the composite steel slag powder admixture has fine particles, which can make the system structure filled more tightly and improve the ability to hinder the penetration and diffusion of Cl ‑ ions; the modified basalt fibers improve the dispersion stability in the matrix and further improve the seawater erosion resistance of the concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly to an iron aluminate cement concrete resistant to seawater erosion and a preparation method thereof. Background Art

[0002] With the large-scale construction of docks, bridges, offshore projects, etc., the adverse effects of seawater on concrete have emerged, that is, the durability problem of concrete becomes very important; traditional portland cement concrete has a porous structure, and water and other harmful ions will penetrate into its interior through the pores, and it often shows certain limitations in the marine environment. Especially when facing the corrosion of multiple complex factors such as salts, climate, and organisms in seawater, its performance often fails to meet the requirements of long-term use; iron aluminate cement, as a new type of cement material, with anhydrous calcium sulfoaluminate and iron phase as the main minerals, forms a series of cements with rapid hardening, expansion, and self-stress. This kind of cement shows good performance in ordinary environments, but its corrosion resistance still has room for improvement in the marine environment.

[0003] At present, in engineering, the method of adjusting the cement mineral ratio is usually adopted to improve the corrosion resistance of iron aluminate cement concrete. However, adjusting the mineral ratio requires adjusting a series of parameters such as the raw material ratio of cement and the firing system, which is too difficult; there is also a method of improving its corrosion resistance by adding other components, such as the compound of expansion agent, mineral admixture, and water reducer. Through the interaction of the above several substances, the compactness of concrete is improved, and then the anti-erosion ability of concrete is improved; but these components only reduce the penetration of chloride ions by increasing the compactness of concrete; the effective components in some corrosion inhibitors with the function of inhibiting chloride ion penetration are mostly nitrites, so their scope of application is limited.

[0004] Steel slag is a solid waste generated during the steelmaking process by artificially adding slag-making agents to clarify the molten steel. Its mineral composition is similar to that of cement clinker, and it has certain hydration activity after being ground fine; siloxane materials have a small molecular structure, and the silicon-oxygen macromolecules formed after hydrolysis and polycondensation are easy to react with the silicon hydroxyl groups on the surface of the concrete substrate, thus playing a role in densifying the concrete structure; the purpose of the present invention is to prepare an iron aluminate cement concrete with excellent seawater corrosion resistance by combining the internal addition of steel slag ultra-fine admixture and the internal infiltration of fluorine-containing quaternary ammonium salt siloxane modifier, significantly improving the mechanical properties and corrosion resistance of the concrete. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and to provide an iron aluminate cement concrete resistant to seawater erosion and a preparation method thereof. This iron aluminate cement has high mechanical strength, resistance to seawater scouring and erosion, and can greatly improve the durability of concrete.

[0006] The present invention is realized through the following technical solutions:

[0007] A seawater erosion-resistant ferroaluminate cement concrete comprises the following components in parts by weight: 70 - 90 parts of ferroaluminate cement, 10 - 30 parts of composite steel slag micro powder admixture, 230 - 280 parts of crushed stone, 180 - 210 parts of quartz sand, 15 - 30 parts of fly ash, 5 - 8 parts of polycarboxylate superplasticizer, 2 - 5 parts of admixture, 1 - 5 parts of modified basalt fiber, 2 - 10 parts of fluorinated quaternary ammonium salt siloxane modifier, and 40 - 50 parts of deionized water.

[0008] The preparation method of the composite steel slag micro powder admixture is as follows: Mix steel slag, slag and zeolite according to a mass ratio of 25:65:10, add an appropriate amount of deionized water, control the solid content at 40 - 45%, grind with an intermittent ball mill, grind to a median particle size of ≤5 μm at 40 - 60°C, add carboxymethyl cellulose and an activator, and stir at room temperature for 15 - 30 min to obtain the composite steel slag micro powder admixture; the activator is a mixture of sodium sulfate, triisopropanolamine and silica powder, and the mass ratio of the three is 2:2:1.

[0009] Further, the admixture is any one of 2 - phosphono - 1,2,4 - butanetricarboxylic acid, sodium gluconate, and hydroxyethylidene diphosphonic acid.

[0010] Further, the preparation method of the modified basalt fiber is as follows: Ultrasonically disperse 10 g of basalt fiber, 2 g of KH560 and 30 mL of ethanol evenly, react at 60°C for 3 h, and obtain it after centrifugal drying.

[0011] Further, the preparation method of the fluorinated quaternary ammonium salt siloxane modifier is as follows:

[0012] Step (1): Under a nitrogen atmosphere, add bis[3 - (trimethoxysilyl)propyl]amine and methanol to a reaction flask, stir evenly, add perfluorohexylethylene, stir and react, after the reaction is completed, concentrate under reduced pressure, and obtain a fluorinated siloxane monomer after drying.

[0013] Step (2): Under a nitrogen atmosphere, add the fluorinated siloxane monomer and N,N - dimethylformamide to a reaction flask, stir evenly, add 3 - bromopropene, react at 80 - 100°C for 16 - 24 h, cool to room temperature, filter, wash with deionized water, and obtain an alkenyl fluorinated siloxane monomer after drying.

[0014] Step (3): Under a nitrogen atmosphere, methyl methacrylate, acrylic acid, 2-acrylamido-2-methylpropionic acid, vinyl fluorosiloxane monomer and deionized water are added to a reaction flask. After stirring evenly, potassium persulfate is dissolved in deionized water to prepare an initiator solution with a mass fraction of 30-40%, and it is added dropwise at a rate of 2-3.5 mL / min. After the addition is completed, the reaction is carried out at 70-85 °C for 1-3 h, and then cooled to 35-45 °C. An aqueous sodium bicarbonate solution is added to adjust the pH to neutral to obtain a fluorinated quaternary ammonium salt siloxane modifier.

[0015] Furthermore, in step (1), the molar ratio of bis[3-(trimethoxysilyl)propyl]amine to perfluorohexylethylene is 1:1.05-1.2.

[0016] Furthermore, in step (1), the reaction temperature is 45-60 °C and the reaction time is 5-12 h.

[0017] Furthermore, in step (2), the molar ratio of the fluorosiloxane monomer to 3-bromopropene is 1:1.1-1.4.

[0018] Furthermore, in step (3), the mass ratio of methyl methacrylate, acrylic acid, 2-acrylamido-2-methylpropionic acid, vinyl fluorosiloxane monomer, and potassium persulfate is 100:10-20:8-15:3-12:4-8.

[0019] Furthermore, the preparation method of the seawater erosion-resistant ferroaluminate cement concrete is as follows: Ferroaluminate cement, composite steel slag powder admixture, crushed stone, quartz sand, and fly ash are poured into a concrete mixer and dry-mixed for 50-80 s. After mixing evenly, an admixture, polycarboxylate superplasticizer, and deionized water are added, and the mixture is stirred for 5-10 min. Then, modified basalt fibers and a fluorinated quaternary ammonium salt siloxane modifier are added and stirred for 10-20 min. After mixing evenly, it is poured into a mold, vibrated for 20-40 s, leveled with a trowel, left standing for 16-24 h to demold, and placed in a steam curing box for steam curing to obtain the seawater erosion-resistant ferroaluminate cement concrete.

[0020] Furthermore, during the steam curing process, it is first left to stand at room temperature for 5-8 h, then cured at a constant temperature of 50-65 °C for 12-16 h, and finally cured naturally for 7-10 days.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention uses bis[3-(trimethoxysilyl)propyl]amine, perfluorohexylethylene, and 3-bromopropene as raw materials to obtain an alkenyl fluorosiloxane monomer through addition and quaternization reactions, and polymerizes it with acrylic monomers to obtain a fluorinated quaternary ammonium salt siloxane modifier. Then, it is compounded with ferrite cement, composite steel slag powder, and modified basalt fibers to obtain a ferrite cement concrete resistant to seawater erosion.

[0023] (1) The fluorinated quaternary ammonium salt siloxane modifier contains organofluorine and organosilicon with good hydrophobic properties, which can form a waterproof layer on the concrete surface to prevent the entry of erosion factors in a physical barrier manner; the positive charge of the quaternary ammonium salt cation can adsorb free chloride ions in the concrete to form a stable compound, reducing the number of free chloride ions in the concrete, thereby reducing the corrosion risk of chloride ions to the concrete; the alkoxy groups in the siloxane can undergo a condensation reaction with the silanol groups on the surface of the concrete substrate after hydrolysis to form a tetrahedral Si-O-Si covalent bond, thus crosslinking into a dense hardened microstructure; the fluorinated quaternary ammonium salt siloxane modifier has relatively rich siloxane bond functional groups on its surface, which will tightly crosslink the hydration products together after combining with the ferrite cement-based material to form a dense grid structure, improving the bonding strength between the hydration products, effectively filling the pores and cracks in the concrete material, and thus improving the mechanical properties and durability of the concrete.

[0024] (2) The composite steel slag powder admixture has fine particles, a smooth surface, and high dispersion, which is beneficial to improving the fluidity of fresh concrete and can fully fill the pores and capillary channels of hardened concrete, densify the concrete, and can undergo a secondary reaction with Ca(OH)2 generated by cement hydration to fill the pores and block the through capillary channels, making the pore size of the cement fly ash paste finer, the pore tortuosity increase, and the connected pores decrease. The addition of the steel slag-based composite admixture makes the system composed of complex particles. Compared with single cement particles, particles of different sizes enter the concrete, changing the pore structure of the concrete, reducing its porosity, and making the pore distribution more uniform, enabling the system structure to be filled more tightly, thereby improving the ability of the concrete to hinder the penetration and diffusion of Cl - ions.

[0025] (3) The modified basalt fiber is modified by KH560, which increases its specific surface area, reduces the interfacial tension, improves the dispersion stability in the matrix, and enhances the compatibility and bonding force with the concrete; the steel slag-based composite admixture, fluorinated quaternary ammonium salt siloxane modifier, and modified basalt fiber have a synergistic effect, forming a spatial network structure, which can make the structure of the concrete more dense, increase the anti-seepage effect of the concrete, and thus improve the anti-seepage performance and corrosion resistance of the concrete, further broadening the application range of the concrete. Specific embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 belong to the scope of protection of the present invention. Unless otherwise specified, the raw materials and reagents used in this application are all commercially available products or can be prepared by known methods.

[0027] Preparation of composite steel slag powder admixture: Mix steel slag, slag and zeolite in a mass ratio of 25:65:10, add an appropriate amount of deionized water, control the solid content at 40-45%, and grind using an intermittent ball mill. Grind to a median particle size of ≤5 μm at 40-60 °C, add carboxymethyl cellulose and an activator, and stir at room temperature for 15-30 min to obtain the composite steel slag powder admixture; the activator is a mixture of sodium sulfate, triisopropanolamine and silica powder, and the mass ratio of the three is 2:2:1.

[0028] The preparation method of modified basalt fiber is as follows: Ultrasonically disperse 10 g of basalt fiber, 2 g of KH560 and 30 mL of ethanol evenly, react at 60 °C for 3 h, and obtain it after centrifugal drying.

[0029] Bis[3-(trimethoxysilyl)propyl]amine, CAS No. 82985-35-1.

[0030] Perfluorohexylethylene, CAS No. 25291-17-2.

[0031] 3-Bromopropene, CAS No. 106-95-6.

[0032] Example 1

[0033] (1) Under a nitrogen atmosphere, add 45 mmol of bis[3-(trimethoxysilyl)propyl]amine and 270 mL of methanol to the reaction flask. After stirring evenly, add 52.2 mmol of perfluorohexylethylene and react at 55 °C for 8 h. Concentrate under reduced pressure and dry to obtain a fluorosiloxane monomer. The preparation reaction formula is as follows:

[0034]

[0035] (2) Under a nitrogen atmosphere, add 42 mmol of fluorosiloxane monomer and 420 mL of N,N-dimethylformamide to the reaction flask. After stirring evenly, add 48.3 mmol of 3-bromopropene and react at 90 °C for 18 h. Cool to room temperature, filter, wash with deionized water, and dry to obtain an alkenyl fluorosiloxane monomer. The preparation reaction formula is as follows:

[0036]

[0037] (3) Under a nitrogen atmosphere, 100 g of methyl methacrylate, 15 g of acrylic acid, 12 g of 2-acrylamido-2-methylpropanoic acid, 3 g of alkenyl fluorosiloxane monomer and 40 mL of deionized water were added to a reaction flask. After stirring evenly, 5 g of potassium persulfate was dissolved in deionized water to prepare an initiator solution with a mass fraction of 35%, and it was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the reaction was carried out at 75 °C for 2 h, then cooled to 30 °C, and an aqueous sodium bicarbonate solution was added to adjust the pH to neutral to obtain a fluorinated quaternary ammonium salt siloxane modifier.

[0038] (4) 90 g of ferroaluminate cement, 10 g of composite steel slag powder admixture, 260 g of crushed stone, 205 g of quartz sand and 25 g of fly ash were poured into a concrete mixer and dry-mixed for 60 s. After mixing evenly, 4 g of 2-phosphono-1,2,4-tricarboxylic acid butane, 6 g of polycarboxylate water reducer and 45 g of deionized water were added, and the mixture was stirred for 8 min. Then 1 g of modified basalt fiber and 2 g of fluorinated quaternary ammonium salt siloxane modifier were added and stirred for 15 min. After mixing evenly, it was poured into a mold, vibrated for 30 s, leveled with a trowel, left standing for 20 h to demold, and placed in a steam curing box for steam curing. First, it was left standing at room temperature for 6 h, then cured at a constant temperature of 60 °C for 14 h, and finally cured naturally for 7 days to obtain ferroaluminate cement concrete resistant to seawater erosion.

[0039] Example 2

[0040] (1) Under a nitrogen atmosphere, 150 mmol of bis[3-(trimethoxysilyl)propyl]amine and 600 mL of methanol were added to a reaction flask. After stirring evenly, 157.5 mmol of perfluorohexylethylene was added, and the reaction was carried out at 60 °C for 5 h. After concentration under reduced pressure and drying, a fluorosiloxane monomer was obtained.

[0041] (2) Under a nitrogen atmosphere, 140 mmol of fluorosiloxane monomer and 1120 mL of N,N-dimethylformamide were added to a reaction flask. After stirring evenly, 154 mmol of 3-bromopropene was added, and the reaction was carried out at 100 °C for 16 h. After cooling to room temperature, filtration, washing with deionized water and drying, an alkenyl fluorosiloxane monomer was obtained.

[0042] (3) Under a nitrogen atmosphere, 100 g of methyl methacrylate, 10 g of acrylic acid, 8 g of 2-acrylamido-2-methylpropanoic acid, 5 g of alkenyl fluorosiloxane monomer and 30 mL of deionized water were added to a reaction flask. After stirring evenly, 4 g of potassium persulfate was dissolved in deionized water to prepare an initiator solution with a mass fraction of 30%, and it was added dropwise at a rate of 2 mL / min. After the addition was completed, the reaction was carried out at 85 °C for 1 h, then cooled to 45 °C, and an aqueous sodium bicarbonate solution was added to adjust the pH to neutral to obtain a fluorinated quaternary ammonium salt siloxane modifier.

[0043] (4) Pour 90 g of ferroaluminate cement, 10 g of composite steel slag powder admixture, 230 g of crushed stone, 180 g of quartz sand, and 30 g of fly ash into a concrete mixer and dry mix for 50 s. After mixing evenly, add 2 g of sodium gluconate, 5 g of polycarboxylate water reducer, and 40 g of deionized water, and mix and stir for 5 min. Then add 2 g of modified basalt fiber and 4 g of fluorinated quaternary ammonium salt siloxane modifier, stir for 10 min, pour the mixture into a mold after mixing evenly, vibrate and compact for 20 s, level with a trowel, let stand for 16 h to demold, and place it in a steam curing box for steam curing. First, let it stand at room temperature for 5 h, then cure at a constant temperature of 65 °C for 12 h, and finally cure naturally for 8 days to obtain ferroaluminate cement concrete resistant to seawater erosion.

[0044] Example 3

[0045] (1) Under a nitrogen atmosphere, add 20 mmol of bis[3-(trimethoxysilyl)propyl]amine and 140 mL of methanol to a reaction flask. After stirring evenly, add 24 mmol of perfluorohexyl ethylene and react at 45 °C for 12 h. Concentrate under reduced pressure and dry to obtain a fluorinated siloxane monomer.

[0046] (2) Under a nitrogen atmosphere, add 15 mmol of fluorinated siloxane monomer and 180 mL of N,N-dimethylformamide to a reaction flask. After stirring evenly, add 21 mmol of 3-bromopropene and react at 80 °C for 24 h. Cool to room temperature, filter, wash with deionized water, and dry to obtain an alkenyl fluorinated siloxane monomer.

[0047] (3) Under a nitrogen atmosphere, add 100 g of methyl methacrylate, 20 g of acrylic acid, 15 g of 2-acrylamido-2-methylpropionic acid, 7 g of alkenyl fluorinated siloxane monomer, and 50 mL of deionized water to a reaction flask. After stirring evenly, dissolve 8 g of potassium persulfate in deionized water to prepare an initiator solution with a mass fraction of 40%, and add it dropwise at a rate of 3.5 mL / min. After the addition is completed, react at 70 °C for 3 h, cool to 35 °C, and add an aqueous sodium bicarbonate solution to adjust the pH to neutral to obtain a fluorinated quaternary ammonium salt siloxane modifier.

[0048] (4) Pour 90 g of ferroaluminate cement, 10 g of composite steel slag powder admixture, 280 g of crushed stone, 210 g of quartz sand, and 15 g of fly ash into a concrete mixer and dry mix for 80 s. After mixing evenly, add 5 g of hydroxyethylidene diphosphonic acid, 8 g of polycarboxylate water reducer, and 50 g of deionized water, and mix and stir for 10 min. Then add 3 g of modified basalt fiber and 6 g of fluorinated quaternary ammonium salt siloxane modifier, stir for 20 min, pour the mixture into a mold after mixing evenly, vibrate for 40 s, level with a trowel, let stand for 24 h and demold, and place it in a steam curing box for steam curing. First, let it stand at room temperature for 8 h, then cure at a constant temperature of 65 °C for 12 h, and finally cure naturally for 9 days to obtain ferroaluminate cement concrete resistant to seawater erosion.

[0049] Example 4

[0050] (1) Under a nitrogen atmosphere, add 80 mmol of bis[3-(trimethoxysilyl)propyl]amine and 440 mL of methanol to a reaction flask. After stirring evenly, add 88 mmol of perfluorohexylethylene and react at 50 °C for 9 h. Concentrate under reduced pressure and dry to obtain a fluorinated siloxane monomer.

[0051] (2) Under a nitrogen atmosphere, add 75 mmol of fluorinated siloxane monomer and 720 mL of N,N-dimethylformamide to a reaction flask. After stirring evenly, add 93 mmol of 3-bromopropene and react at 95 °C for 20 h. Cool to room temperature, filter, wash with deionized water, and dry to obtain an alkenyl fluorinated siloxane monomer.

[0052] (3) Under a nitrogen atmosphere, add 100 g of methyl methacrylate, 16 g of acrylic acid, 14 g of 2-acrylamido-2-methylpropionic acid, 10 g of alkenyl fluorinated siloxane monomer, and 35 mL of deionized water to a reaction flask. After stirring evenly, dissolve 7 g of potassium persulfate in deionized water to prepare an initiator solution with a mass fraction of 32%, and add it dropwise at a rate of 3 mL / min. After the addition is complete, react at 80 °C for 3 h, cool to 30 °C, and add an aqueous sodium bicarbonate solution to adjust the pH to neutral to obtain a fluorinated quaternary ammonium salt siloxane modifier.

[0053] (4) Pour 90 g of ferroaluminate cement, 10 g of composite steel slag powder admixture, 245 g of crushed stone, 190 g of quartz sand, and 25 g of fly ash into a concrete mixer and dry mix for 65 s. After mixing evenly, add 3 g of 2-phosphono-1,2,4-tricarboxylic acid butane, 6 g of polycarboxylate water reducer, and 48 g of deionized water, and mix and stir for 8 min. Then add 4 g of modified basalt fiber and 8 g of fluorinated quaternary ammonium salt siloxane modifier, stir for 15 min, inject into a mold after mixing evenly, vibrate for 35 s, level with a trowel, let stand for 24 h and demold, and place in a steam curing box for steam curing. First, cure at room temperature for 6 h, then cure at a constant temperature of 60 °C for 15 h, and finally cure naturally for 10 days to obtain ferroaluminate cement concrete resistant to seawater erosion.

[0054] Example 5

[0055] (1) Under a nitrogen atmosphere, add 32 mmol of bis[3-(trimethoxysilyl)propyl]amine and 175 mL of methanol to a reaction flask. After stirring evenly, add 36.8 mmol of perfluorohexylethylene and react at 50 °C for 12 h. Concentrate under reduced pressure and dry to obtain a fluorinated siloxane monomer.

[0056] (2) Under a nitrogen atmosphere, add 25 mmol of fluorinated siloxane monomer and 255 mL of N,N-dimethylformamide to a reaction flask. After stirring evenly, add 32 mmol of 3-bromopropene and react at 85 °C for 18 h. Cool to room temperature, filter, wash with deionized water, and dry to obtain an alkenyl fluorinated siloxane monomer.

[0057] (3) Under a nitrogen atmosphere, add 100 g of methyl methacrylate, 14 g of acrylic acid, 12 g of 2-acrylamido-2-methylpropanoic acid, 12 g of alkenyl fluorinated siloxane monomer, and 40 mL of deionized water to a reaction flask. After stirring evenly, dissolve 5 g of potassium persulfate in deionized water to prepare an initiator solution with a mass fraction of 35%, and add it dropwise at a rate of 2.5 mL / min. After the addition is completed, react at 75 °C for 2 h, cool to 40 °C, and add an aqueous sodium bicarbonate solution to adjust the pH to neutral to obtain a fluorinated quaternary ammonium salt siloxane modifier.

[0058] (4) Pour 90 g of ferroaluminate cement, 10 g of composite steel slag powder admixture, 270 g of crushed stone, 205 g of quartz sand, and 25 g of fly ash into a concrete mixer and dry mix for 75 s. After mixing evenly, add 4 g of sodium gluconate, 8 g of polycarboxylate water reducer, and 50 g of deionized water, and mix and stir for 10 min. Then add 5 g of modified basalt fiber and 10 g of fluorinated quaternary ammonium salt siloxane modifier, stir for 20 min, pour the mixture into a mold after mixing evenly, vibrate and compact for 30 s, level with a trowel, let stand for 20 h and demold, and place it in a steam curing box for steam curing. First, let it stand at room temperature for 6 h, then cure at a constant temperature of 60 °C for 16 h, and finally cure naturally for 10 days to obtain ferroaluminate cement concrete resistant to seawater erosion.

[0059] Comparative Example 1

[0060] (1) Under a nitrogen atmosphere, add 100 g of methyl methacrylate, 15 g of acrylic acid, 12 g of 2-acrylamido-2-methylpropionic acid, 3 g of 3-(methacryloyloxy)propyltrimethoxysilane (CAS No. 2530-85-0, structural formula ) and 40 mL of deionized water into a reaction flask. After stirring evenly, dissolve 5 g of potassium persulfate in deionized water to prepare an initiator solution with a mass fraction of 35%, and add it dropwise at a rate of 2.5 mL / min. After the addition is completed, react at 75 °C for 2 h, cool down to 30 °C, and add an aqueous sodium bicarbonate solution to adjust the pH to neutral to obtain a siloxane modifier.

[0061] (2) Pour 90 g of ferroaluminate cement, 10 g of composite steel slag powder admixture, 260 g of crushed stone, 205 g of quartz sand, and 25 g of fly ash into a concrete mixer and dry mix for 60 s. After mixing evenly, add 4 g of 2-phosphono-1,2,4-tricarboxylic acid butane, 6 g of polycarboxylate water reducer, and 45 g of deionized water, and mix and stir for 8 min. Then add 1 g of modified basalt fiber and 2 g of siloxane modifier, stir for 15 min, pour the mixture into a mold after mixing evenly, vibrate and compact for 30 s, level with a trowel, let stand for 20 h and demold, and place it in a steam curing box for steam curing. First, let it stand at room temperature for 6 h, then cure at a constant temperature of 60 °C for 14 h, and finally cure naturally for 7 days to obtain ferroaluminate cement concrete.

[0062] Comparative Example 2

[0063] (1) Under a nitrogen atmosphere, 100 g of methyl methacrylate, 15 g of acrylic acid, 12 g of 2-acrylamido-2-methylpropanoic acid, and 40 mL of deionized water were added to a reaction flask. After stirring evenly, 5 g of potassium persulfate was dissolved in deionized water to prepare an initiator solution with a mass fraction of 35%, and it was added dropwise at a rate of 2.5 mL / min. After the addition was completed, the reaction was carried out at 75 °C for 2 h. Then, the temperature was lowered to 30 °C, and an aqueous sodium bicarbonate solution was added to adjust the pH to neutral to obtain an acrylic resin.

[0064] (2) 90 g of ferrite cement, 10 g of composite steel slag powder admixture, 260 g of crushed stone, 205 g of quartz sand, and 25 g of fly ash were poured into a concrete mixer and dry-mixed for 60 s. After mixing evenly, 4 g of 2-phosphono-1,2,4-tricarboxylic acid butane, 6 g of polycarboxylate water reducer, and 45 g of deionized water were added, and the mixture was stirred for 8 min. Then, 1 g of modified basalt fiber and 2 g of acrylic resin were added, and the mixture was stirred for 15 min. After mixing evenly, it was poured into a mold, vibrated for 30 s, leveled with a trowel, left standing for 20 h and then demolded, and placed in a steam curing box for steam curing. First, it was left standing at room temperature for 6 h, then cured at a constant temperature of 60 °C for 14 h, and finally cured naturally for 7 days to obtain ferrite cement concrete.

[0065] Comparative Example 3

[0066] 100 g of ferrite cement, 260 g of crushed stone, 205 g of quartz sand, and 25 g of fly ash were poured into a concrete mixer and dry-mixed for 60 s. After mixing evenly, 4 g of 2-phosphono-1,2,4-tricarboxylic acid butane, 6 g of polycarboxylate water reducer, and 45 g of deionized water were added, and the mixture was stirred for 8 min. Then, 1 g of modified basalt fiber was added, and the mixture was stirred for 15 min. After mixing evenly, it was poured into a mold, vibrated for 30 s, leveled with a trowel, left standing for 20 h and then demolded, and placed in a steam curing box for steam curing. First, it was left standing at room temperature for 6 h, then cured at a constant temperature of 60 °C for 14 h, and finally cured naturally for 7 days to obtain ferrite cement concrete.

[0067] Electric flux test: Referring to the standard of GB / T 50082-2009, the concrete was prepared into specimens with a diameter of 100 mm and a height of 50 mm, and the electric flux of the concrete specimens was measured using a concrete chloride ion electric flux measuring instrument. The experimental solution was 3% NaCl solution.

[0068] Acid and alkali resistance test: The prepared concrete was made into specimens with dimensions of 200 mm × 200 mm × 100 mm, and they were respectively immersed in a 15% dilute sulfuric acid and sodium hydroxide solution. The liquid level was 30 mm higher than the upper surface of the specimen, and the minimum distance between the specimen and the container wall was 30 mm. The solution temperature was maintained at 25 °C. After 28 days, the specimens were taken out, the surface was cleaned with water, and then they were placed in a standard curing room for 2 days, and then taken out to observe the surface condition.

[0069] Table 1 Corrosion Resistance Performance Test

[0070]

[0071]

[0072] The smaller the electric flux of the concrete, the better the compactness of the concrete, and it can better resist the erosion of the chloride ion environment. From the test results in the above table, it can be seen that with the increase of the content of the fluorinated quaternary ammonium salt siloxane modifier, the corrosion resistance of the ferroaluminate cement concrete gradually increases. Among them, the electric flux in Example 4 is only 330 C, showing good seawater corrosion resistance. This is because on the one hand, the fluorinated quaternary ammonium salt siloxane modifier contains organofluorine and organosilicon with good hydrophobic properties, which can form a waterproof layer on the concrete surface to prevent the entry of erosion factors in a physical barrier manner; the positive charge of the quaternary ammonium salt cation can adsorb with the free chloride ions in the concrete to form a stable compound, reducing the number of free chloride ions in the concrete, thereby reducing the corrosion risk of chloride ions to the concrete; at the same time, after the siloxane is hydrolyzed to hydroxyl groups, it can undergo hydrolysis condensation reaction with the silanol groups on the surface of the concrete substrate to form a tetrahedral Si-O-Si covalent bond, thereby crosslinking into a dense hardened microstructure. On the other hand, the composite steel slag powder admixture reacts with Ca(OH)2 generated by cement hydration for a secondary reaction, which can fill the pores and block the through capillary pore channels, making the pore size of the cement fly ash paste finer, the pore tortuosity increase, and the connected pores decrease, thereby improving the ability of the concrete to hinder the - ion penetration and diffusion. In Comparative Example 1, there are no organofluorine and quaternary ammonium salt groups, and in Comparative Example 2, there are no organosilicon fluorine and quaternary ammonium salts, and their corrosion resistance is average; in Comparative Example 3, there are no organic modifiers and composite steel slag powder admixtures, and its corrosion resistance is the worst.

[0073] Mechanical Property Test: According to GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the compressive strength and flexural strength of the prepared concrete were tested. The specimen size was 100 mm × 100 mm × 100 mm, and the loading rate given by the universal testing machine was 2.4 kN / s.

[0074] Table 2 Compressive Strength and Flexural Strength Test

[0075] Compressive strength (MPa) Flexural strength (MPa) Example 1 69.4 5.4 Example 2 77.8 6.1 Example 3 84.5 6.9 Example 4 92.1 7.5 Example 5 93.4 7.6 Comparative Example 1 50.3 5.2 Comparative Example 2 41.7 4.8 Comparative Example 3 35.3 4.2

[0076] The modified basalt fiber is modified by KH560, which increases its specific surface area, reduces the interfacial tension, improves the dispersion stability in the matrix, and enhances the compatibility and bonding strength with concrete; the fluorinated quaternary ammonium salt siloxane modifier has relatively abundant siloxane bond functional groups on its surface. After combining with the ferroaluminate cement-based material, it will crosslink the hydration products tightly together to form a dense grid structure, improving the bonding strength between the hydration products and effectively filling the pores and cracks in the concrete material; the steel slag-based composite admixture has fine particles, a smooth surface, and a high dispersion degree, which is beneficial to improving the fluidity of fresh concrete and can fully fill the pores and capillary channels of hardened concrete, densifying the concrete, thereby improving the mechanical properties and durability of the concrete.

[0077] Example 6

[0078] The difference between this example and Example 4 is that the addition amount of the composite steel slag powder admixture is 15 g, and the addition amount of the ferroaluminate cement is 85 g, and other conditions remain the same.

[0079] Example 7

[0080] The difference between this example and Example 4 is that the addition amount of the composite steel slag powder admixture is 20 g, and the addition amount of the ferroaluminate cement is 80 g, and other conditions remain the same.

[0081] Example 8

[0082] The difference between this example and Example 4 is that the addition amount of the composite steel slag powder admixture is 25 g, and the addition amount of the ferroaluminate cement is 75 g, and other conditions remain the same.

[0083] Example 9

[0084] The difference between this example and Example 4 is that the addition amount of the composite steel slag powder admixture is 30 g, and the addition amount of the ferroaluminate cement is 70 g, and other conditions remain the same.

[0085] Comparative Example 4

[0086] The difference between this example and Example 4 is that no composite steel slag powder admixture is added, and the addition amount of the ferroaluminate cement is 100 g, and other conditions remain the same.

[0087] Impermeability performance test: Referring to the GB / T 50082-2009 standard, the water penetration resistance of the concrete is tested by the water penetration height method. The concrete is made into a frustum with an inner diameter of 180 mm at the upper mouth, an inner diameter of 190 mm at the lower mouth, and a height of 250 mm, and placed in a concrete permeameter for water penetration resistance test, with the water pressure added being 1.5 MPa.

[0088] Electric Flux Test: Referring to the standard of GB / T 50082-2009, concrete specimens with a diameter of 100 mm and a height of 50 mm were prepared, and the electric flux of the concrete specimens was measured using a concrete chloride ion electric flux measuring instrument. The experimental solution was 3% NaCl solution.

[0089] Table 3 Anti-permeability Performance and Corrosion Resistance Performance Test

[0090]

[0091] With the increase in the content of steel slag-based composite admixture, the anti-permeability performance and anti-chloride ion performance of concrete are enhanced. This is because the addition of steel slag-based composite admixture makes the system composed of complex particles. Compared with single cement particles, particles of different sizes enter the concrete, changing the pore structure of the concrete, reducing its porosity, and making the pore distribution more uniform, which can make the system structure filled more tightly; the steel slag-based composite admixture, fluorine-containing quaternary ammonium salt siloxane modifier, and modified basalt fiber have a synergistic effect, forming a spatial network structure, which can make the structure of the concrete more dense, increase the anti-permeability effect of the concrete, and further broaden the application range of the concrete.

[0092] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, which all belong to the protection scope of the present application; the methods used in the present application are conventional methods unless otherwise specified.

Claims

1. A seawater-resistant ferroaluminate cement concrete, characterized in that, The ferroaluminate cement concrete comprises the following components in parts by weight: 70-90 parts of ferroaluminate cement, 10-30 parts of composite steel slag micro powder admixture, 230-280 parts of crushed stone, 180-210 parts of quartz sand, 15-30 parts of fly ash, 5-8 parts of polycarboxylate superplasticizer, 2-5 parts of admixture, 1-5 parts of modified basalt fiber, 2-10 parts of fluorinated quaternary ammonium salt siloxane modifier and 40-50 parts of deionized water; The preparation method of the composite steel slag micro powder admixture is as follows: mixing steel slag, slag and zeolite according to a mass ratio of 25:65:10, adding an appropriate amount of deionized water, controlling the solid content to be 40-45%, grinding with an intermittent ball mill, grinding to a median particle size of ≤5 μm at 40-60 °C, adding carboxymethyl cellulose and an activator, and stirring at room temperature for 15-30 min to obtain the composite steel slag micro powder admixture; the activator is a mixture of sodium sulfate, triisopropanolamine and silica powder, and the mass ratio of the three is 2:2:1; The preparation method of the fluorinated quaternary ammonium salt siloxane modifier is as follows: Step (1): Under a nitrogen atmosphere, add bis[3-(trimethoxysilyl)propyl]amine and methanol to a reaction flask, stir evenly, add perfluorohexylethylene, stir and react, after the reaction is completed, concentrate under reduced pressure, and dry to obtain a fluorosiloxane monomer; Step (2): Under a nitrogen atmosphere, add the fluorosiloxane monomer and N,N-dimethylformamide to a reaction flask, stir evenly, add 3-bromopropene, react at 80-100 °C for 16-24 h, cool to room temperature, filter, wash with deionized water, and dry to obtain an alkenyl fluorosiloxane monomer; Step (3): Under a nitrogen atmosphere, add methyl methacrylate, acrylic acid, 2-acrylamido-2-methylpropionic acid, the alkenyl fluorosiloxane monomer and deionized water to a reaction flask, stir evenly, dissolve potassium persulfate in deionized water to prepare an initiator solution with a mass fraction of 30-40%, and add it dropwise at a rate of 2-3.5 mL / min. After the dropwise addition is completed, react at 70-85 °C for 1-3 h, cool to 35-45 °C, and add an aqueous sodium bicarbonate solution to adjust the pH to neutral to obtain the fluorinated quaternary ammonium salt siloxane modifier.

2. The seawater erosion-resistant calcium ferrite cement concrete according to claim 1, wherein The admixture is any one of 2-phosphono-1,2,4-tricarboxylic acid butane, sodium gluconate, and hydroxyethylidene diphosphonic acid.

3. The seawater erosion-resistant ferroaluminate cement concrete according to claim 1, characterized in that, The preparation method of the modified basalt fiber is as follows: ultrasonically disperse 10 g of basalt fiber, 2 g of KH560 and 30 mL of ethanol evenly, react at 60 °C for 3 h, and centrifuge and dry to obtain it.

4. The seawater erosion-resistant ferroaluminate cement concrete according to claim 1, wherein, In the step (1), the molar ratio of bis[3-(trimethoxysilyl)propyl]amine to perfluorohexylethylene is 1:1.05-1.

2.

5. The seawater erosion-resistant ferroaluminate cement concrete according to claim 1, characterized in that In the step (1), the reaction temperature is 45-60 °C, and the reaction time is 5-12 h.

6. The seawater erosion-resistant ferroaluminate cement concrete according to claim 1 and its preparation method are characterized in that, In the step (2), the molar ratio of the fluorosiloxane monomer to 3-bromopropene is 1:1.1-1.

4.

7. The seawater erosion-resistant ferroaluminate cement concrete according to claim 1, wherein In the step (3), the mass ratio of methyl methacrylate, acrylic acid, 2-acrylamido-2-methylpropionic acid, vinyl fluorosiloxane monomer, and potassium persulfate is 100:10 - 20:8 - 15:3 - 12:4 - 8.

8. A preparation method of seawater erosion-resistant ferroaluminate cement concrete according to any one of claims 1-7, characterized in that, The preparation method is as follows: Pour ferrite cement, composite steel slag powder admixture, crushed stone, quartz sand, and fly ash into a concrete mixer and dry mix for 50 - 80 s. After mixing evenly, add an admixture, polycarboxylate superplasticizer, and deionized water, and mix and stir for 5 - 10 min. Then add modified basalt fiber and fluorinated quaternary ammonium salt siloxane modifier, stir for 10 - 20 min. After mixing evenly, pour it into a mold, vibrate and compact for 20 - 40 s, level it with a trowel, let it stand for 16 - 24 h to demold, and place it in a steam curing box for steam curing to obtain ferrite cement concrete resistant to seawater erosion.

9. The preparation method of the seawater erosion-resistant ferroaluminate cement concrete according to claim 8, characterized in that The steam curing process is to first rest at room temperature for 5 - 8 h, then carry out constant temperature curing at 50 - 65 °C for 12 - 16 h, and finally carry out natural curing for 7 - 10 days.

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