A recycled aggregate concrete electric pole and a preparation method thereof

Abstract

This invention discloses a recycled aggregate concrete pole and its preparation method, belonging to the field of concrete technology. The recycled aggregate concrete pole of this invention comprises corrosion-resistant reinforcing steel bars treated with an anti-corrosion coating and recycled aggregate concrete; the anti-corrosion coating comprises an anti-corrosion copolymer; the anti-corrosion copolymer comprises 10-20 parts of benzotriazole functional monomer, 10-20 parts of 3-methacryloyloxypropyltrimethoxysilane, 15-25 parts of methacryloylethyl sulfobetaine, 8-16 parts of glycidyl methacrylate, 5-9 parts of octadecyl methacrylate, 2-6 parts of dimethyl vinylphosphonate, 12-26 parts of methyl methacrylate, and 4-12 parts of butyl methacrylate. This invention achieves long-term corrosion protection and synergistic improvement of structural durability in the recycled aggregate concrete pole by constructing an organic-inorganic hybrid dual-anchoring anti-corrosion coating on the surface of the reinforcing steel bars and forming a chemical gradient interface with the recycled aggregate concrete.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to a concrete pole using recycled aggregate and its preparation method. Background Technology

[0002] Recycled aggregate concrete poles, which use recycled aggregate from crushed waste concrete to replace natural aggregate, represent an important direction for achieving solid waste resource utilization and the green and low-carbon transformation of the building materials industry. However, recycled aggregates have old cement paste adhering to their surface, resulting in significantly higher porosity than natural aggregates. This leads to an accelerated migration rate of moisture and corrosive ions within the concrete. In the service environment of the poles, the reinforcing bars are subjected to the coupled effects of highly alkaline pore fluid and high salt flux, significantly increasing the risk of pitting corrosion induction and propagation. This, in turn, causes cracking and spalling of the concrete cover, ultimately leading to pole structural failure. Existing reinforcing bar protection measures mainly include epoxy coatings and silane impregnation. However, epoxy coatings rely solely on physical adsorption to bond with the reinforcing bar surface, resulting in insufficient wet adhesion in humid and alkaline environments, making them prone to blistering and peeling. Silane impregnation layers are only nanometer thick; although they can form chemical bonds with the reinforcing bar surface, they cannot provide an effective ion barrier or sufficient physical shielding thickness. Furthermore, in existing technologies, corrosion inhibitors are mostly introduced into the coating through physical doping, which easily dissolves and is lost after long-term immersion in concrete pore fluid, limiting the protective lifespan. Therefore, there is still a technological gap in the long-term durability protection of steel reinforcement in recycled aggregate concrete poles. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this invention provides a concrete pole using recycled aggregate and its preparation method. The technical solution to achieve the objective of this invention is as follows: A type of concrete pole using recycled aggregate, wherein the reinforcing steel of the concrete pole is treated with an anti-corrosion coating, the anti-corrosion coating comprising, by weight, 100 parts of an anti-corrosion copolymer, 40-60 parts of anhydrous ethanol, 20-40 parts of anhydrous butyl acetate, 0.3-0.8 parts of crosslinking catalyst, 1-3 parts of rheology modifier, 0.5-1 parts of leveling agent, and 0.3-0.8 parts of defoamer; the anti-corrosion copolymer comprising, by weight, copolymer monomers comprising: 10-20 parts of benzotriazole functional monomer, 10-20 parts of 3-methacryloyloxypropyltrimethoxysilane, 15-25 parts of methacryloylethyl sulfobetaine, 8-16 parts of glycidyl methacrylate, 5-9 parts of octadecyl methacrylate, 2-6 parts of dimethyl vinylphosphonate, 12-26 parts of methyl methacrylate, and 4-12 parts of butyl methacrylate.

[0004] The sum of all the monomers is 100 parts by weight; the weight ratio of methacryloylethyl sulfobetaine to octadecyl methacrylate is (1.5~3):1; the rheology modifier is selected from polyamide wax-type rheology modifiers; the leveling agent is selected from organosilicon leveling agents; the defoamer is selected from polysiloxane defoamers; the crosslinking catalyst is selected from 2,4,6-tris(dimethylaminomethyl)phenol.

[0005] The preparation method of the preservative copolymer includes the following steps: mixing 3-methacryloyloxypropyltrimethoxysilane, methacryloylethyl sulfobetaine, glycidyl methacrylate, dimethyl vinylphosphonate, methyl methacrylate, and butyl methacrylate as a monomer solution for later use; dissolving the benzotriazole functional monomer in a solvent and adding a portion of the initiator for later use; dissolving the remaining initiator in a solvent for later use; and simultaneously and slowly adding the two initiator-containing solutions to the monomer solution for reaction. After the reaction is completed, the preservative copolymer is purified to obtain the preservative copolymer.

[0006] The initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and di-tert-butyl peroxide.

[0007] The preparation method of the benzotriazole functional monomer includes the following steps: Aniline compounds were diazotized and coupled with m-phenylenediamine to obtain azophenylenediamine compounds. The azophenylenediamine compounds were then heated under reflux in the presence of copper salt and pyridine to oxidize and cyclize to obtain 2-phenyl-2H-benzotriazole-5-amine. Monoallyl sulfide diglycidyl ether was mixed with 2-phenyl-2H-benzotriazole-5-amine and a catalyst, and purified to obtain benzotriazole functional monomers.

[0008] The reaction is carried out under nitrogen protection; the aniline compound is selected from one or more of 4-methylaniline, 4-ethylaniline, 4-propylaniline, 4-n-butylaniline, 4-sec-butylaniline, 4-tert-butylaniline, 4-pentylaniline, 4-hexylaniline, 4-heptylaniline, 4-octylaniline, 4-nonylaniline, and 4-decylaniline; the copper salt is selected from copper acetate monohydrate, copper chloride dihydrate, copper nitrate trihydrate, and sulfuric acid pentahydrate. The catalyst is selected from one or more of copper and anhydrous copper acetate; the molar ratio of the monoallyl sulfide diglycidyl ether to 2-phenyl-2H-benzotriazole-5-amine is 1:(2.0~2.2); the catalyst is selected from one or more of 2,4,6-tris(dimethylaminomethyl)phenol, triethylamine, N,N-dimethylbenzylamine, 2-methylimidazole, and 2-ethyl-4-methylimidazole; the amount of the catalyst is 0.03~0.07 parts.

[0009] The method for preparing the monoallyl thioether diglycidyl ether includes the following steps: under argon protection, 4-mercaptophenol is deprotonated and then reacted with 3-chloro-2-chloromethylprop-1-ene, and purified to obtain monoallyl thioether bisphenol; then, monoallyl thioether bisphenol is reacted with epichlorohydrin under the action of a phase transfer catalyst and a base, and purified to obtain monoallyl thioether diglycidyl ether.

[0010] The molar ratio of 4-mercaptophenol to 3-chloro-2-chloromethylprop-1-ene is (2.5~3.5):1; the molar ratio of monoallyl thioether bisphenol to epichlorohydrin is 1:(4~6); the phase transfer catalyst is selected from one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, hexadecyltrimethylammonium bromide, and trioctylmethylammonium chloride.

[0011] The method for preparing the anti-corrosion coating includes the following steps: under nitrogen protection, the anti-corrosion copolymer is added to a mixed solvent of anhydrous ethanol and anhydrous butyl acetate and stirred at room temperature to dissolve; a crosslinking catalyst, rheology modifier, leveling agent and defoamer are added and stirring is continued; the mixture is filtered to obtain the anti-corrosion coating; the coating is sealed in a nitrogen headspace container and stored at 5~25℃.

[0012] The concrete pole also includes recycled aggregate concrete; the recycled aggregate concrete, by weight, comprises 350-420 parts cement, 800-900 parts recycled coarse aggregate, 600-700 parts recycled fine aggregate, 60-100 parts fly ash, 10-30 parts silica fume, 6-10 parts polycarboxylate superplasticizer, and 130-160 parts water; wherein the water, cement, fly ash, and silica fume meet the water-cement ratio of 0.28-0.32, the sum of fly ash and silica fume does not exceed 35% of the total weight of the cementitious materials, and the recycled fine aggregate and recycled coarse aggregate meet the sand ratio of 30%-50%.

[0013] Another object of the present invention is to protect the preparation method of the concrete pole using recycled aggregate, comprising the following steps: sandblasting the steel bar to Sa2.5 grade with a surface roughness Ra of 40~70 μm, cleaning it, and then coating it with the anti-corrosion coating as described above or the anti-corrosion coating prepared by the method described above, controlling the wet film thickness to 80~120 μm, curing it at room temperature to allow silane hydrolysis and condensation, and then heat curing to allow epoxy-amine ring-opening crosslinking to obtain anti-corrosion steel bar; mixing the recycled aggregate with cement, fly ash, silica fume, water-reducing agent and water to form concrete, pouring it into a mold containing the anti-corrosion steel bar, centrifuging to form it, and obtaining the recycled aggregate concrete pole after steam curing and standard curing.

[0014] This invention utilizes the synergistic effect of multifunctional groups in the side chains of the anti-corrosion copolymer to construct a multi-scale protection system on the surface of steel bars, ranging from molecular to macroscopic levels.

[0015] First, the interface employs a dual anchoring layer. The trimethoxysilane group of the 3-methacryloxypropyltrimethoxysilane side chain hydrolyzes in moisture to form silanetriol, which dehydrates and condenses with hydroxylated iron oxide on the steel reinforcement surface to form Fe-O-Si covalent bonds. The phosphonate group of the dimethyl vinylphosphonate side chain hydrolyzes in the alkaline environment of concrete to form phosphonic acid groups, which form stable coordination chelates with oxides on the iron surface. These two anchoring mechanisms are independent and complementary. Even if reversible hydrolysis of local silicon-oxygen bonds occurs in strongly alkaline micro-regions, the phosphonic acid coordination anchor can still maintain interfacial connectivity, and vice versa, thus providing redundant wet adhesion protection.

[0016] Second, the coating exhibits a hybrid cross-linked network. Self-condensation between silanetriols forms a three-dimensional Si-O-Si inorganic glassy network, interspersed between organic polymer segments, creating an organic-inorganic hybrid structure that improves coating density and solvent resistance. During the thermosetting stage, the epoxy groups on the glycidyl methacrylate side chain undergo ring-opening reactions with the secondary amine and hydroxyl groups on the benzotriazole side chain, generating ether bonds and a tertiary amine cross-linked network. This ether bond network exhibits superior saponification resistance in strong alkalis compared to traditional ester or urethane bonds. Even if a small number of ester groups undergo hydrolysis during long-term service, the ether bond cross-linked network can still maintain the overall integrity of the coating.

[0017] Third, the external surface features multi-scale ion and water barriers. The sulfobetaine inner salt of the methacryloyl ethyl sulfobetaine side chain does not dissociate in strong alkalis, forming a dense hydrated layer on the coating surface through electrostatic induction. This generates a hydration entropy repulsion effect, hindering corrosive ions such as chloride ions from approaching the coating surface. The long-chain octadecyl methacrylate forms low-surface-energy hydrophobic microdomains on the outer surface of the coating, reducing the permeability coefficient of liquid water molecules. The hydrophilic hydrated layer and the hydrophobic alkyl chain are complementary at the nanoscale, with the epoxy crosslinking network limiting the phase domain size and preventing the hydrophilic channels from penetrating.

[0018] Fourth, defect passivation and zero-loss corrosion inhibition. The benzotriazole ring is covalently fixed to the polymer side chain. When corrosive ions penetrate the coating and reach the surface of the steel reinforcement, they coordinate with the active sites on the iron surface through nitrogen atoms, forming a local hydrophobic adsorption layer. This increases the anodic reaction overpotential and inhibits pitting corrosion nucleation. Since the benzotriazole ring is not a physical dopant, the problem of corrosion inhibitor migration and loss is avoided.

[0019] Fifth, the coating is chemically compatible with concrete. The residual silanol groups on the outer surface of the coating accumulate at the coating-concrete interface and undergo condensation reactions with the silanol groups in the CSH gel, a cement hydration product, to form Si-O-Si covalent bonds. This creates a chemical gradient interface from metal to inorganic cement among the steel reinforcement, coating, and concrete, eliminating the risk of interfacial delamination.

[0020] Beneficial effects

[0021] In the preparation system of the recycled aggregate concrete pole of this invention, the anti-corrosion treatment of the steel reinforcement surface is the key to ensuring the long-term service durability of the component. The technical advantages of this invention mainly rely on the design of the anti-corrosion coating for the steel reinforcement and its multi-scale interface mechanism, specifically manifested as follows: (1) Enhanced dual-anchoring interface. The coating forms Fe-O-Si covalent bonds with the steel reinforcement surface through silanol salts, and simultaneously forms stable coordination chelates with iron oxides through phosphonate groups, constituting an organic-inorganic dual-anchoring system. The two anchoring mechanisms are independent and complementary. Even if local silicon-oxygen bonds undergo reversible hydrolysis in strongly alkaline micro-regions, the phosphonate coordination anchor can still maintain the interfacial connection, and vice versa. This significantly improves the wet adhesion of the coating in humid and alkaline environments, avoiding the blistering and peeling of traditional physical adsorption coatings.

[0022] (2) Alkali-resistant and saponification-resistant crosslinking network. The coating body is based on a carbon-carbon skeleton, and the side chains form ether bonds and tertiary amine crosslinking networks through epoxy-amine ring opening. This ether bond network has significantly better hydrolysis resistance than the ester bonds in traditional polyurethane or epoxy ester coatings in the highly alkaline environment of concrete pore fluid. Even if a small amount of methacrylate side groups undergo alkali-catalyzed hydrolysis during long-term service, the ether bond crosslinking network can still maintain the overall integrity of the coating and prevent catastrophic failure.

[0023] (3) Multi-scale ion and water barrier. The sulfobetaine inner salt side chain forms a dense hydrated layer on the coating surface, which prevents corrosive ions such as chloride ions from approaching the steel reinforcement surface through the hydration entropy repulsion effect; the long-chain octadecyl side chain provides low surface energy hydrophobic micro-regions, reducing the permeability coefficient of liquid water molecules. The hydrophilic hydrated layer and the hydrophobic alkyl chain complement each other at the nanoscale, and the epoxy cross-linking network restricts the phase domain size, preventing hydrophilic channels from penetrating, forming a physical and chemical synergistic water and chloride barrier.

[0024] (4) Low leaching corrosion inhibition and defect passivation. The benzotriazole ring is fixed to the polymer side chain by covalent bonds, avoiding the migration and dissolution problems of physically doped corrosion inhibitors. When corrosive ions penetrate the coating and reach the surface of the steel bar, the benzotriazole ring coordinates with the active sites on the iron surface through nitrogen atoms to form a local hydrophobic adsorption layer, which inhibits pitting corrosion nucleation and achieves long-term chemical protection of the steel bar.

[0025] (5) Endogenous crosslinking and no curing agent migration. The side chains of the benzotriazole functional monomer have secondary amine and hydroxyl groups, which can directly undergo ring-opening crosslinking with epoxy groups during the thermosetting stage. There is no need to use large doses of small molecule amine curing agents. Only a small amount of crosslinking promoter is needed to achieve rapid crosslinking, which reduces the amount of small molecule curing agent used, reduces the risk of its migration and loss, and ensures that the coating maintains a stable network structure during its service life.

[0026] (6) Chemical compatibility between the coating and concrete. The residual silanol groups on the outer surface of the coating accumulate at the coating-concrete interface and undergo condensation reaction with the silanol groups in the CSH gel, a cement hydration product, to form Si-O-Si covalent bonds. This makes the steel reinforcement, coating, and concrete form a chemical gradient interface from metal to inorganic cement, rather than a completely separate multiphase system, fundamentally eliminating the risk of interfacial delamination and avoiding becoming a weak channel for water and ion penetration.

[0027] (7) Adaptable to the production and service environment of recycled aggregate poles. The coating completes silane hydrolysis and condensation anchoring under room temperature and humidity conditions, and epoxy-amine crosslinking is completed in the subsequent heating stage. This curing sequence ensures that chemical anchoring precedes the formation of a dense organic network, adapting to the steam curing regime in pole production. At the same time, the flexible monomer segments and rigid crosslinking network in the coating work together to adapt to the thermal expansion difference between the steel reinforcement and the recycled aggregate concrete, reducing the risk of coating cracking under temperature cycling. Attached Figure Description

[0028] Figure 1 Synthetic route diagram for benzotriazole functional monomer 1.

[0029] Figure 2 The image shows the 1H NMR spectrum of benzotriazole functional monomer 1. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0032] The raw materials and equipment used in the examples and comparative examples are described below, where eq represents molar equivalent: Crosslinking catalyst: 2,4,6-tris(dimethylaminomethyl)phenol, commercially available.

[0033] Rheology modifier: BYK-410, commercially available.

[0034] Leveling agent: BYK-333, commercially available.

[0035] Defoamer: BYK-066N, commercially available.

[0036] Recycled coarse aggregate: particle size 10~20 mm, conforming to the technical requirements of Class II recycled coarse aggregate in JGJ / T 240-2011 "Technical Specification for Application of Recycled Aggregate", commercially available.

[0037] Recycled fine aggregate: particle size 0~5 mm, conforming to the technical requirements of Class II recycled fine aggregate in JGJ / T 240-2011 "Technical Specification for Application of Recycled Aggregate", commercially available.

[0038] Cement: Silicate cement, PII 52.5R, commercially available.

[0039] Fly ash: Grade II fly ash, commercially available.

[0040] Silica fume: SiO2 with an average particle size of 0.1~0.3μm, commercially available.

[0041] Polycarboxylate superplasticizer: PCA®-Ⅳ, purchased from Jiangsu Subote.

[0042] Water: Tap water, meeting the requirements of the standard "Mixing Water for Concrete" (JGJ 63-2006).

[0043] Commercially available anti-corrosion coatings: acrylic anti-corrosion coatings that meet the requirements of "Soluble-based Acrylic Resin Coatings" (GB / T 25264-2010).

[0044] 2-p-tert-butylphenyl-2H-benzotriazole-5-amine: Prepared in-house, the preparation method is as follows: Dissolve 1.0 eq of 4-tert-butylaniline in 10 mL of methanol with stirring. Slowly add 2.8 eq of 12M hydrochloric acid while cooling in an ice bath. Cool the solution to 0°C and continue stirring. Slowly add 1 mL of 1.2 eq of sodium nitrite aqueous solution to generate the diazonium salt intermediate in situ over 15 min, and continue stirring for 10 min. In a separate reaction vessel, dissolve 1.5 eq of m-phenylenediamine in 15 mL of a 2:1 methanol-water mixture and stir in an ice bath. Pre-adjust the pH to 5.5 with dilute hydrochloric acid. While maintaining the reaction system temperature at 3–5°C, slowly add the above diazonium salt solution to the mixed solution. During the addition, add 0.5 M sodium hydroxide solution to maintain the pH at 5–6. Continue stirring at 3–5°C for 30 min, then add 200 mL of sodium hydroxide solution. 4-p-tert-butylphenylazo-1,3-phenylenediamine was obtained by precipitating an orange solid in 15 mL of tetrahydrofuran. After filtration and thorough washing, 1.0 eq of 4-p-tert-butylphenylazo-1,3-phenylenediamine was dissolved in 15 mL of tetrahydrofuran. 4.2 eq of copper acetate monohydrate and 10 mL of pyridine were added with stirring, and the mixture was heated to reflux for 3 h. After the reaction, volatile components were removed by vacuum distillation. The residue was extracted with 200 mL of ethyl acetate and washed three times with 50 mL of 0.1 M disodium ethylenediaminetetraacetate aqueous solution each time. The organic phase was dried over anhydrous magnesium sulfate, filtered, concentrated, and then separated by silica gel column chromatography using a 5:1 (dichloromethane to ethyl acetate) mixed solvent containing 0.5% (v / v) triethylamine as the eluent to obtain 2-p-tert-butylphenyl-2H-benzotriazole-5-amine, the structure of which is shown below. .

[0045] 2-p-Methylphenyl-2H-benzotriazole-5-amine: prepared in-house, the preparation method is the same as that of 2-p-tert-butylphenyl-2H-benzotriazole-5-amine, except that 4-tert-butylaniline is replaced with 4-methylaniline, and all other conditions remain the same, to obtain 2-p-methylphenyl-2H-benzotriazole-5-amine.

[0046] Monoallyl thioether diglycidyl ether: prepared in-house, the preparation method is as follows: Under argon protection, 3.0 eq of 4-mercaptophenol was dissolved in 15 mL of dry 2-methyltetrahydrofuran, and 3 eq of sodium hydride was added. The mixture was stirred at 0 °C for 30 min to form a suspension. Separately, 1.0 eq of 3-chloro-2-chloromethylprop-1-ene was dissolved in 15 mL of dry 2-methyltetrahydrofuran and slowly added dropwise to the above suspension over 35 min with vigorous stirring. After the addition was complete, the reaction mixture was heated to 45 °C and reacted for 3 h. The mixture was then cooled to 0 °C, and anhydrous ethanol was slowly added dropwise under argon protection until no bubbles were generated to quench excess sodium hydride. The mixture was diluted with 50 mL of dry toluene, filtered to remove inorganic salts, and the filter cake was washed twice with 20 mL of dry toluene. The organic phases were combined. The organic phase was washed twice with 0.5 M dilute hydrochloric acid, and then twice with water until neutral. The organic phase was dried over anhydrous magnesium sulfate, filtered, concentrated under reduced pressure, and purified by column chromatography to obtain monoallyl thioether bisphenol. The content of monoallyl thioether bisphenol was 1.0 eq. eq, mix it with 5.0 eq epichlorohydrin and heat to 45℃ and stir until homogeneous; separately, dissolve 2.0 eq sodium hydroxide and 0.07 eq benzyltriethylammonium chloride in 30 mL water, and slowly add the alkali solution dropwise to the above mixture over 30 min at 45℃ with stirring. After the addition is complete, keep the reaction at this temperature for 3 h, taking samples every 1 h for thin-layer chromatography monitoring until the bisphenol starting material spot disappears; after cooling to room temperature, add 100 mL toluene and 50 mL water to the reaction system for dilution, stir, allow to stand and separate, discard the aqueous phase, wash the organic phase twice with water, and then use a 0.05 concentration... M was washed twice rapidly with hydrochloric acid, then twice with water until neutral. All aqueous phases were combined and extracted three times with ethyl acetate. All organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and excess epichlorohydrin was recovered by vacuum distillation. The residue was concentrated under reduced pressure below 40°C and purified by silica gel column chromatography using a mixed solvent of toluene and ethyl acetate (7:1 v / v) containing 1% acetone as the eluent. The eluent was concentrated under reduced pressure below 40°C and slurried with a mixed solvent of diethyl ether and isopropanol (1:1 v / v) at a solid-liquid ratio of 1 g: 10 mL. After stirring at room temperature for 30 min, the mixture was filtered to obtain monoallyl thioether diglycidyl ether, with the structure shown below: .

[0047] Benztriazole functional monomer 1: bis(2-(4-tert-butylphenyl)-2H-benzotriazole-5-yl) monoallyl thioether bisphenol di(2-hydroxy-3-propylamine): self-prepared, preparation method as follows: Under nitrogen protection, 1.0 eq of monoallyl sulfide diglycidyl ether and 2.1 eq of 2-p-tert-butylphenyl-2H-benzotriazole-5-amine were dissolved in anhydrous N,N-dimethylformamide. 0.05 eq of 2,4,6-tris(dimethylaminomethyl)phenol was added as a catalyst. The mixture was heated to 90 °C and stirred for 6 h, with samples taken every 1 h for thin-layer chromatography monitoring until the epoxy starting material spot disappeared. After the reaction was completed, the mixture was cooled to room temperature, poured into 300 mL of ice water, and 20 eq of [unclear - possibly a specific ingredient or substance] was added. The organic phases were extracted three times with ethyl acetate after stirring with sodium chloride solution for 30 min. The combined organic phases were washed twice with saturated sodium chloride solution and then twice with water until neutral. The organic phase was dried over anhydrous magnesium sulfate, filtered, concentrated under reduced pressure, and then purified by silica gel column chromatography using a mixed solvent of dichloromethane and methanol (volume ratio 10:1) containing 0.5% triethylamine as the eluent to obtain bis(2-(4-tert-butylphenyl)-2H-benzotriazole-5-yl)monallyl thioether bisphenol di(2-hydroxy-3-propylamine), i.e., benzotriazole functional monomer 1, with the structure shown below: .

[0048] Benzotriazole functional monomer 2: prepared in-house. The preparation method is the same as that of benzotriazole functional monomer 1, except that 2-p-tert-butylphenyl-2H-benzotriazole-5-amine is replaced with 2-p-methylphenyl-2H-benzotriazole-5-amine, while other conditions remain unchanged, to obtain benzotriazole functional monomer 2.

[0049] Functional monomer 3: prepared in-house. The preparation method is the same as that of benzotriazole functional monomer 1, except that 2-p-tert-butylphenyl-2H-benzotriazole-5-amine is replaced with 4-methylaniline, while other conditions remain unchanged, to obtain functional monomer 3.

[0050] Anticorrosive copolymer 1: Self-made, preparation method is as follows: Under nitrogen protection, 15 parts of 3-methacryloyloxypropyltrimethoxysilane, 20 parts of methacryloylethyl sulfobetaine, 12 parts of glycidyl methacrylate, 4 parts of dimethyl vinylphosphonate, 18 parts of methyl methacrylate, and 8 parts of butyl methacrylate were dissolved in a mixed solvent of 160 mL anhydrous toluene and 60 mL anhydrous N,N-dimethylformamide. The mixture was heated to 75°C and stirred until dissolved. 15 parts of benzotriazole functional monomer 1 were dissolved in a mixed solvent of 40 mL anhydrous toluene and 10 mL anhydrous N,N-dimethylformamide, and 1.5 parts of azobisisobutyronitrile were added, placed in a constant-pressure dropping funnel. Separately, 1.5 parts of azobisisobutyronitrile were dissolved in 20 mL anhydrous toluene and placed in another constant-pressure dropping funnel. The contents of the reaction flask were equilibrated at 75°C under a nitrogen atmosphere for 30 minutes. After 3 minutes, two streams of liquid were added slowly and simultaneously, with the dropping rate controlled to maintain the dropping time at 3 hours. After the dropping was complete, the temperature was raised to 80°C and the reaction was continued at this temperature for 8 hours. During this period, samples were taken every 2 hours for Fourier transform infrared spectroscopy to monitor the characteristic absorption peak of the carbon-carbon double bond until the peak area no longer decreased. After the reaction was completed, the mixture was cooled to room temperature and, under vigorous stirring, the reaction solution was slowly poured into a pre-cooled 500 mL mixture of anhydrous n-hexane and anhydrous acetone in a volume ratio of 5:1 to precipitate the copolymer. After filtration, the copolymer was washed three times with anhydrous n-hexane and dried in a vacuum drying oven at 45°C and a vacuum of 0.09 MPa for 24 hours to obtain the dried anticorrosive copolymer 1. The entire operation was carried out under nitrogen protection and in a dry environment with a dew point not higher than -20°C. The obtained anticorrosive copolymer 1 was sealed and stored under nitrogen.

[0051] Preservative copolymer 2: Prepared in-house. The preparation method is the same as that of preservative copolymer 1, except that benzotriazole functional monomer 1 is replaced with 10 parts, 3-methacryloyloxypropyltrimethoxysilane is replaced with 10 parts, methacryloylethyl sulfobetaine is replaced with 15 parts, glycidyl methacrylate is replaced with 16 parts, octadecyl methacrylate is replaced with 5 parts, dimethyl vinylphosphonate is replaced with 6 parts, methyl methacrylate is replaced with 26 parts, and butyl methacrylate is replaced with 12 parts. All other conditions remain unchanged to obtain preservative copolymer 2.

[0052] Anticorrosive copolymer 3: Prepared in-house. The preparation method is the same as that of anticorrosive copolymer 1, except that benzotriazole functional monomer 1 is replaced with 20 parts, 3-methacryloyloxypropyltrimethoxysilane is replaced with 20 parts, methacryloylethyl sulfobetaine is replaced with 25 parts, glycidyl methacrylate is replaced with 8 parts, octadecyl methacrylate is replaced with 9 parts, dimethyl vinylphosphonate is replaced with 2 parts, methyl methacrylate is replaced with 12 parts, and butyl methacrylate is replaced with 4 parts. All other conditions remain unchanged to obtain anticorrosive copolymer 3.

[0053] Anticorrosive copolymer 4: prepared in-house. The preparation method is the same as that of anticorrosive copolymer 1, except that benzotriazole functional monomer 1 is replaced with benzotriazole functional monomer 2, while other conditions remain unchanged, thus obtaining anticorrosive copolymer 4.

[0054] Anticorrosive copolymer 5: prepared in-house. The preparation method is the same as that of anticorrosive copolymer 1, except that the benzotriazole functional monomer 1 is replaced with functional monomer 3, while all other conditions remain unchanged, thus obtaining anticorrosive copolymer 5. Table 1 Formulations of anti-corrosion copolymers 1 to 5 (by weight)

[0055] Preparation Example Preparation Example 1 Anti-corrosion coating 1: Self-made, preparation method is as follows: Under nitrogen protection, 100 parts of the anti-corrosion copolymer 1 were added to a mixed solvent of 50 parts anhydrous ethanol and 30 parts anhydrous butyl acetate, and stirred at room temperature for 2 h until completely dissolved. 0.5 parts of 2,4,6-tris(dimethylaminomethyl)phenol as a crosslinking catalyst, 2 parts of dehydrated rheology modifier, 0.8 parts of leveling agent, and 0.5 parts of defoamer were added, and stirring was continued for 1 h. The mixture was filtered through a 200-mesh drying filter to obtain the anti-corrosion coating. The coating was sealed in a nitrogen headspace container and stored at 20°C, with the moisture content controlled below 100 ppm.

[0056] Anti-corrosion coating 2: self-made. The preparation method is the same as that of anti-corrosion coating 1, except that anti-corrosion copolymer 1 is replaced with anti-corrosion copolymer 2, while other conditions remain unchanged, thus obtaining anti-corrosion coating 2.

[0057] Anti-corrosion coating 3: self-made. The preparation method is the same as that of anti-corrosion coating 1, except that anti-corrosion copolymer 1 is replaced with anti-corrosion copolymer 3, while other conditions remain unchanged, thus obtaining anti-corrosion coating 3.

[0058] Anti-corrosion coating 4: self-made. The preparation method is the same as that of anti-corrosion coating 1, except that anti-corrosion copolymer 1 is replaced with anti-corrosion copolymer 4, while other conditions remain unchanged, thus obtaining anti-corrosion coating 4.

[0059] Anti-corrosion coating 5: self-made. The preparation method is the same as that of anti-corrosion coating 1, except that anti-corrosion copolymer 1 is replaced with anti-corrosion copolymer 5, while other conditions remain unchanged, thus obtaining anti-corrosion coating 5.

[0060] Examples 1-6 and Comparative Examples 1-3 Example 1

[0061] Recycled aggregate concrete pole 1: Self-made, preparation method as follows: S1. Surface treatment and coating of steel bars: HRB400 steel bars were sandblasted to Sa2.5 grade with a surface roughness of Ra50 μm; the sandblasted steel bars were immersed in anhydrous ethanol and ultrasonically cleaned for 15 min, and then dried with nitrogen to ensure that the surface was free of water and oil; anti-corrosion coating 1 was applied by air spraying, and the wet film thickness was controlled to be 100 μm; the surface was dried by standing for 30 min at room temperature of 25℃ and relative humidity of 60%, and then the surface was cured with moisture for 48 h to allow the side chain trimethoxysilyl groups to fully hydrolyze and condense, forming Fe-O-Si covalent bonds and a three-dimensional siloxane network on the surface of the steel bars; then the surface was transferred to a forced-air drying oven and pre-dried at 60℃ for 1 h to remove residual solvent, and then heated to 110℃ and kept at the temperature for 3 h to allow the epoxy groups to fully open the ring and cross-link with the secondary amine and hydroxyl groups of the benzotriazole side chain to form a dense ether bond cross-linking network, resulting in anti-corrosion steel bar 1 with a dry film thickness of 50 μm; S2. Preparation of Recycled Aggregate Concrete Poles: Recycled coarse and fine aggregates are washed and dried until the moisture content is no higher than 3%. By weight, 380 parts cement, 850 parts recycled coarse aggregate, 650 parts recycled fine aggregate, 80 parts fly ash, 20 parts silica fume, 6 parts polycarboxylate superplasticizer, and 144 parts water are mixed to form concrete. The above-mentioned anti-corrosion steel bars are tied into a pole reinforcement cage. Sharp impacts are avoided during handling and tying. Before placement into the formwork, the coating integrity is visually inspected. Minor scratches are manually applied with the same coating. After surface drying at room temperature for 2 hours, the pole can be placed into the formwork to continue the residual cross-linking reaction in the alkaline environment of the concrete. According to the relevant provisions of GB / T 4623-2014 "Circular Concrete Poles," the same steel reinforcement cage is used to prepare a tapered pole with a wall thickness of 50 mm, a taper of 1 / 75, a tip diameter of 190 mm, a root diameter of 350 mm, and a pole length of 12 mm. For a concrete pole measuring m, the concrete mixture is poured in layers into a steel mold and centrifuged to ensure the concrete is dense and evenly distributed. The centrifuged pole with mold is then placed in a curing kiln and cured with constant-temperature steam at 60℃ for 10 hours to allow the concrete to reach the required strength for demolding. After demolding, the pole is placed in a standard curing environment with a temperature of 20℃ and a relative humidity of ≥95% and cured continuously for 28 days to obtain the recycled aggregate concrete pole 1.

[0062] Example 2

[0063] Recycled aggregate concrete pole 2: Self-made. The preparation method is the same as that of recycled aggregate concrete pole 1, except that cement is replaced with 350 parts, recycled coarse aggregate with 800 parts, recycled fine aggregate with 600 parts, fly ash with 60 parts, silica fume with 10 parts, polycarboxylate superplasticizer with 6 parts, and water with 130 parts. All other conditions remain the same.

[0064] Example 3

[0065] Recycled aggregate concrete pole 3: Self-made. The preparation method is the same as that of recycled aggregate concrete pole 1, except that cement is replaced with 420 parts, recycled coarse aggregate with 900 parts, recycled fine aggregate with 700 parts, fly ash with 100 parts, silica fume with 30 parts, polycarboxylate superplasticizer with 10 parts, and water with 160 parts. All other conditions remain the same, thus obtaining recycled aggregate concrete pole 3.

[0066] Example 4

[0067] Recycled aggregate concrete pole 4: self-made. The preparation method is the same as that of recycled aggregate concrete pole 1, except that anti-corrosion coating 1 is replaced with anti-corrosion coating 2, while other conditions remain unchanged, thus obtaining recycled aggregate concrete pole 4.

[0068] Example 5

[0069] Recycled aggregate concrete pole 5: self-made. The preparation method is the same as that of recycled aggregate concrete pole 1, except that anti-corrosion coating 1 is replaced with anti-corrosion coating 3, while other conditions remain unchanged, thus obtaining recycled aggregate concrete pole 5.

[0070] Example 6

[0071] Recycled aggregate concrete pole 6: self-made. The preparation method is the same as that of recycled aggregate concrete pole 1, except that the anti-corrosion coating 1 is replaced with anti-corrosion coating 4, while other conditions remain unchanged, thus obtaining recycled aggregate concrete pole 6.

[0072] Comparative Example 1 Recycled aggregate concrete pole 7: self-made. The preparation method is the same as that of recycled aggregate concrete pole 1, except that the anti-corrosion coating 1 is replaced with anti-corrosion coating 5, while other conditions remain unchanged, thus obtaining recycled aggregate concrete pole 7.

[0073] Comparative Example 2 Recycled aggregate concrete pole 8: Self-made. The preparation method is the same as that of recycled aggregate concrete pole 1, except that the anti-corrosion coating 1 is replaced with commercially available anti-corrosion coating, while other conditions remain unchanged, thus obtaining recycled aggregate concrete pole 8.

[0074] Comparative Example 3 Recycled aggregate concrete pole 9: Self-made. The preparation method is the same as that of recycled aggregate concrete pole 1. The difference is that the anti-corrosion coating 1 is not used to treat the steel bars. All other conditions remain the same, and recycled aggregate concrete pole 9 is obtained.

[0075] The following are the test methods for performance parameters involved in this invention: 1. Nuclear magnetic resonance hydrogen spectrum test: Characterization was performed using a nuclear magnetic resonance spectrometer (Bruker AM-600, Avance 600).

[0076] 2. Compressive strength, bending moment and crack resistance coefficient test: The compressive strength, bending moment and crack resistance coefficient of the recycled aggregate concrete pole specimens after curing 1 to 7 were tested in accordance with GB / T 4623-2014 "Circular Concrete Poles". Each circular specimen was divided into three pieces as a group. The results are shown in Table 2.

[0077] 3. Flexural strength: The test was conducted according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". A cuboid specimen with a cross-section of 100 mm × 100 mm and a length of 400 mm was used. The flexural strength was tested after curing under the same conditions as the pole. The results are shown in Table 2.

[0078] 4. Corrosion current density test: The linear polarization principle method was adopted, and the results were evaluated in accordance with GB / T 50344-2019 "Technical Standard for Testing Building Structures". A three-electrode system was used (steel bar as working electrode, saturated calomel electrode as reference electrode, and stainless steel mesh as auxiliary electrode). The test was conducted in concrete pore fluid with 0.1 M sodium chloride simulating pH 12.5. The polarization potential range relative to the open circuit potential was ±10 mV, and the scan rate was 0.166 mV / s. Non-damaged sections were taken out for testing 1 day and 90 days after the steel bar was embedded in the concrete.

[0079] Table 2 Performance test results of Examples 1-6 and Comparative Examples 1-3

[0080] Table 2 shows that the compressive and flexural strengths of Examples 1-3 are at similar levels, with minor fluctuations mainly due to changes in the total amount of cementitious materials and the proportion of aggregates in the concrete mix design. Example 4 reduced the content of siloxane and benzotriazole functional monomers, resulting in decreased chemical anchoring density and corrosion inhibition capacity of the coating, leading to weakened interfacial bonding between the reinforcing steel and concrete, and a decrease in bending moment and crack resistance coefficient compared to Example 1. Example 5 increased the content of siloxane and benzotriazole functional monomers, enhancing the chemical anchoring and corrosion inhibition effect of the coating on the reinforcing steel surface, effectively suppressing the pitting corrosion tendency of the reinforcing steel in alkaline pore liquid, thus improving the crack resistance coefficient. In Example 6, after replacing tert-butyl with p-methylphenyl, the hydrophobic barrier effect of the coating weakened, and its bending moment and crack resistance coefficient were slightly lower than those of Example 1, indicating that the difference in hydrophobicity of aromatic ring substituents affects the interfacial protection effect.

[0081] Comparative Example 1, lacking a benzotriazole corrosion inhibitor group, was more prone to pitting corrosion of the reinforcing steel in the alkaline pore liquid of concrete. The volume expansion of corrosion products led to a decrease in the bond strength between the reinforcing steel and the concrete interface, and caused microcracks in the concrete cover. This was directly reflected in a significant reduction in bending moment and crack resistance coefficient. Within 28 days, the corrosion was not severe enough to significantly weaken the concrete itself, so its compressive and flexural strengths decreased less compared to the Example group. Comparative Example 2 used a commercially available anti-corrosion coating, which provided basic physical isolation, but lacked a dual anchoring system of siloxane chemical anchoring and phosphonic acid coordination anchoring. The coating and reinforcing steel interface relied mainly on physical adsorption, resulting in insufficient wet adhesion. Its bending moment and crack resistance coefficient were lower than those of the Example group. Comparative Example 3 did not undergo any anti-corrosion treatment on the reinforcing bars. Its bending moment and crack resistance coefficient were the lowest among all test groups, and its crack resistance coefficient was lower than the specification requirements. Its flexural strength test value was low because the specimen underwent brittle fracture along the protective layer cracks caused by the corrosion of the reinforcing bars. This phenomenon indicates that the uncoated reinforcing bars have already undergone significant early corrosion in the high humidity environment of recycled aggregate.

[0082] Furthermore, the corrosion current density in the embodiment is lower than that in the comparative example, indicating that the dual-anchoring anti-corrosion coating of the present invention can maintain the integrity of the passivation film on the steel reinforcement surface for a long time even in a high-porosity, high-salt-flux environment of recycled aggregate. Fluctuations in the total amount of cementitious materials and the proportion of aggregates in the mix proportion have a limited impact on the corrosion current density, further demonstrating that the multi-scale protection mechanism of the coating itself is the dominant factor in inhibiting the electrochemical corrosion of the steel reinforcement.

[0083] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A type of concrete pole using recycled aggregate, characterized in that, The steel bars of the concrete poles are treated with an anti-corrosion coating. The anti-corrosion coating, by weight, comprises 100 parts of an anti-corrosion copolymer, 40-60 parts of anhydrous ethanol, 20-40 parts of anhydrous butyl acetate, 0.3-0.8 parts of crosslinking catalyst, 1-3 parts of rheology modifier, 0.5-1 parts of leveling agent, and 0.3-0.8 parts of defoamer. The anti-corrosion copolymer, by weight, comprises: 10-20 parts of benzotriazole functional monomer, 10-20 parts of 3-methacryloyloxypropyltrimethoxysilane, 15-25 parts of methacryloylethyl sulfobetaine, 8-16 parts of glycidyl methacrylate, 5-9 parts of octadecyl methacrylate, 2-6 parts of dimethyl vinylphosphonate, 12-26 parts of methyl methacrylate, and 4-12 parts of butyl methacrylate.

2. The concrete pole using recycled aggregate as described in claim 1, characterized in that, The crosslinking catalyst is selected from 2,4,6-tris(dimethylaminomethyl)phenol; the rheology modifier is selected from polyamide wax-type rheology modifiers; the leveling agent is selected from organosilicon leveling agents; the defoamer is selected from polysiloxane defoamers; the weight ratio of methacryloylethyl sulfobetaine to octadecyl methacrylate is (1.5~3):1, and the sum of all components is 100 parts.

3. The concrete pole using recycled aggregate as described in claim 1, characterized in that, The preparation method of the preservative copolymer includes the following steps: mixing 3-methacryloyloxypropyltrimethoxysilane, methacryloylethyl sulfobetaine, glycidyl methacrylate, dimethyl vinylphosphonate, methyl methacrylate, and butyl methacrylate as a monomer solution for later use; dissolving the benzotriazole functional monomer in a solvent and adding a portion of the initiator for later use; dissolving the remaining initiator in a solvent for later use; and simultaneously and slowly adding the two initiator-containing solutions to the monomer solution for reaction. After the reaction is completed, the preservative copolymer is purified to obtain the preservative copolymer.

4. The concrete pole using recycled aggregate as described in claim 1, characterized in that, The method for preparing the benzotriazole functional monomer includes the following steps: diazotizing an aniline compound and coupling it with m-phenylenediamine to obtain an azophenylenediamine compound; then heating the azophenylenediamine compound under reflux in the presence of copper salt and pyridine to oxidize and cyclize it to obtain 2-phenyl-2H-benzotriazole-5-amine; mixing monoallyl sulfide diglycidyl ether with 2-phenyl-2H-benzotriazole-5-amine and a catalyst, purifying the mixture, and obtaining the benzotriazole functional monomer.

5. The concrete pole using recycled aggregate as described in claim 4, characterized in that, The reaction conditions are under nitrogen protection; the aniline compound is selected from one or more of 4-methylaniline, 4-ethylaniline, 4-propylaniline, 4-n-butylaniline, 4-sec-butylaniline, 4-tert-butylaniline, 4-pentylaniline, 4-hexylaniline, 4-heptylaniline, 4-octylaniline, 4-nonylaniline, and 4-decylaniline; the copper salt is selected from copper acetate monohydrate, copper chloride dihydrate, copper nitrate trihydrate, copper sulfate pentahydrate, and other non-copper compounds. The catalyst is selected from one or more of copper acetate aqueous solution; the molar ratio of the monoallyl sulfide diglycidyl ether to 2-p-tert-butylphenyl-2H-benzotriazole-5-amine is 1:(2.0~2.2); the catalyst is selected from one or more of 2,4,6-tris(dimethylaminomethyl)phenol, triethylamine, N,N-dimethylbenzylamine, 2-methylimidazole, and 2-ethyl-4-methylimidazole; the amount of the catalyst is 0.03~0.07 parts.

6. The concrete pole using recycled aggregate as described in claim 4, characterized in that, The method for preparing the monoallyl thioether diglycidyl ether includes the following steps: deprotonating 4-mercaptophenol and reacting it with 3-chloro-2-chloromethylprop-1-ene, purifying it to obtain monoallyl thioether bisphenol; then reacting the monoallyl thioether bisphenol with epichlorohydrin under the action of a phase transfer catalyst and a base, purifying it to obtain monoallyl thioether diglycidyl ether.

7. The concrete pole using recycled aggregate as described in claim 6, characterized in that, The molar ratio of 4-mercaptophenol to 3-chloro-2-chloromethylprop-1-ene is (2.5~3.5):1; the molar ratio of monoallyl thioether bisphenol to epichlorohydrin is 1:(4~6); the phase transfer catalyst is selected from one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, hexadecyltrimethylammonium bromide, and trioctylmethylammonium chloride.

8. The concrete pole using recycled aggregate as described in claim 1, characterized in that, The method for preparing the anti-corrosion coating includes the following steps: adding the anti-corrosion copolymer to a mixed solvent of anhydrous ethanol and anhydrous butyl acetate, stirring and dissolving at room temperature; adding a crosslinking catalyst, rheology modifier, leveling agent and defoamer, and continuing to stir; filtering to obtain the anti-corrosion coating, and storing it in a sealed container.

9. The concrete pole using recycled aggregate as described in claim 1, characterized in that, The concrete pole also includes recycled aggregate concrete; the recycled aggregate concrete, by weight, includes 350-420 parts cement, 800-900 parts recycled coarse aggregate, 600-700 parts recycled fine aggregate, 60-100 parts fly ash, 10-30 parts silica fume, 6-10 parts polycarboxylate superplasticizer, and 130-160 parts water.

10. The method for preparing a concrete pole using recycled aggregate as described in any one of claims 1 to 9, characterized in that, The process includes the following steps: the steel bars are sandblasted to Sa2.5 grade with a surface roughness of Ra 40~70 μm, cleaned, coated with anti-corrosion paint, cured at room temperature and humidity, and then heat-cured to obtain anti-corrosion steel bars; recycled aggregates are mixed with cement, fly ash, silica fume, water-reducing agent and water to form concrete, which is poured into a mold containing anti-corrosion steel bars, centrifuged, and cured with steam and standard curing to obtain recycled aggregate concrete poles.

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