A self-excited geopolymer anticorrosive coating and a preparation method thereof

Abstract

The application discloses a kind of self-activated geopolymer anticorrosion coating and preparation method thereof, which is prepared with modified fly ash hollow microsphere, superfine slag powder, recycled concrete micro powder, desulfurization gypsum, activated red mud powder, carbide slag powder, wood ash powder, polycarboxylic acid water reducing agent, defoaming agent and the like as raw materials;The modified fly ash hollow microsphere is modified calcium-iron hydrotalcite coated with fly ash hollow microsphere.In-situ growth of calcium-iron hydrotalcite loaded with DTPMP inside acid-treated fly ash hollow microspheres using microwave-assisted technology can improve the effect of geopolymer anticorrosion coating on replacing harmful ions and improve its corrosion resistance;At the same time, the modified red mud powder, carbide slag powder and wood ash powder can form a ternary alkaline environment rich in Ca(OH), Na(OH) and Ka(OH) when they come into contact with water, which can stimulate more complete geopolymerization of silicate and aluminate precursors, thus obtaining a self-activated geopolymer anticorrosion coating that is strong, dense and resistant to chloride ion penetration.

Description

Technical Field

[0001] The present invention belongs to the field of geopolymer-based anti-corrosion coatings, and in particular relates to a self-excited geopolymer anti-corrosion coating and a preparation method thereof, which is intended to effectively protect reinforced concrete structures in coastal environments. Background Art

[0002] Reinforced concrete structures are a widely used engineering structure worldwide. However, their durability is severely threatened by corrosion from corrosive chemicals such as chloride, sulfate, and carbonate ions. High concentrations of corrosive ions (especially chloride) in seawater, particularly in coastal environments, significantly exacerbate this corrosion. These ions penetrate the concrete's pores and reach the steel reinforcement, destroying the steel's self-healing passivation layer. This leads to corrosion of the steel, further damaging and potentially failing the reinforced concrete structure.

[0003] Geopolymer, an inorganic polymer, is produced by the excitation reaction of aluminosilicate materials under alkaline conditions. Its unique three-dimensional spatial network structure is derived from the dissolution and re-condensation process of aluminosilicate. The inherent durability of this structure and its good adhesion to cement-based materials and construction steel make geopolymer an ideal surface corrosion protection coating. Its anti-corrosion mechanism mainly relies on the reaction of CASH and CSH with Cl - Physical adsorption of Cl - Chemical adsorption. Due to the unique two-dimensional structure of hydrotalcite, it has good anion replacement ability. Therefore, many researchers have added hydrotalcite to anti-corrosion coatings to improve the coating's adsorption capacity for harmful chloride ions, thereby improving the corrosion resistance of the coating in harsh environments. However, due to the strong van der Waals interaction between hydrotalcites, directly adding hydrotalcite to the coating can easily cause the hydrotalcite powder to agglomerate. At the same time, due to the strong ion replacement ability of hydrotalcite, in the early stage of the hydration reaction of the geopolymer coating, hydrotalcite is easy to react with the free Cl inside the geopolymer. - 、SO4 2- 、CO3 2- The premature replacement reaction occurs, significantly weakening the hydrotalcite's ion replacement capacity after the geopolymer coating hardens. Furthermore, hydrotalcite is mostly synthesized using traditional hydrothermal methods, which are time-consuming, have strict requirements on the synthesis temperature, and are complex and costly, making them unsuitable for large-scale synthesis.

[0004] At present, commonly used geopolymer activators, such as sodium silicate, sodium hydroxide and other strong alkaline chemicals, can quickly promote the dissolution of aluminosilicate into silicon-oxygen tetrahedron SiO4 4- and aluminum oxide tetrahedron AlO45- , and then these compounds re-condense and harden. This process easily leads to the rapid setting phenomenon of geopolymer slurry, which limits the ease of use and construction time of the coating, and the coating has a large self-shrinkage in the early stage, and is prone to cracking during the hardening process. In addition, these strong alkaline activators usually need to be pre-prepared in a specific proportion, which increases the difficulty of construction, and they are corrosive to a certain extent, making them inconvenient for long-term storage and transportation. Therefore, more and more scholars are committed to studying a method that only requires the addition of water and relies on the alkaline environment formed by the gelling material when it meets water to carry out geopolymerization. However, the alkaline environment formed by industrial solid waste has the problems of low strength, large early self-shrinkage, and resistance to Cl in actual use. - Problems such as poor permeability. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a self-excited geopolymer anti-corrosion coating and a preparation method thereof.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A self-excited geopolymer anti-corrosion coating comprises the following raw materials in parts by weight: 20-30 parts of modified fly ash hollow microspheres, 30-40 parts of ultrafine slag powder, 20-30 parts of recycled concrete powder, 10-20 parts of desulfurized gypsum, 5-10 parts of activated red mud powder, 10-20 parts of calcium carbide slag powder, 5-10 parts of wood ash powder, 0.2-0.3 parts of polycarboxylic acid water reducer, 0.3-0.5 parts of defoaming agent, and 50-60 parts of deionized water.

[0008] Furthermore, the modified fly ash hollow microspheres are specifically fly ash hollow microspheres coated with modified calcium iron hydrotalcite; the preparation thereof comprises the following steps:

[0009] 1) Fly ash hollow microspheres were added to deionized water at a solid-liquid ratio of 1 g:10 mL, the pH value was adjusted to 1.5-2, and the mixture was stirred at room temperature for 2 h. The mixture was filtered, washed with deionized water three times, and placed in a drying oven at 60°C for 4 h to obtain pretreated fly ash hollow microspheres.

[0010] 2) The fly ash hollow microspheres pretreated in step 1) were added to deionized water at a solid-liquid ratio of 1 g:10 mL. After ultrasonic dispersion, calcium nitrate hexahydrate (Ca(NO3)2·6H2O), ferric nitrate nonahydrate (Fe(NO3)2·9H2O), and diethylenetriaminepenta(methylenephosphonic acid) (DTPMP) were added. The pH was adjusted to 10-11, and the mixture was stirred at 46-50°C for 2 h. The mixture was then transferred to a vacuum oven and placed for 1 h to obtain a suspension.

[0011] 3) The suspension obtained in step 2) was subjected to microwave treatment, cooled to room temperature, filtered, washed three times with deionized water, and then transferred to a vacuum drying oven at 60° C. and dried for 8 h to obtain modified calcium iron hydrotalcite coated with fly ash hollow microspheres.

[0012] Furthermore, the frequency of the ultrasonic dispersion in step 2) is 20-40 kHz, and the time is 8-15 minutes.

[0013] Furthermore, the mass ratio of the pretreated fly ash hollow microspheres, calcium nitrate hexahydrate, ferric nitrate nonahydrate and DTPMP used in step 2) is 5:1.2:1.1:0.8.

[0014] Furthermore, the microwave treatment in step 3) is performed at a temperature of 85-90° C., a power of 450 W, and a time of 30 min.

[0015] Furthermore, the activated red mud powder is prepared by placing the red mud powder in a muffle furnace and calcining it at 700° C. for 4 hours (heating rate of 5° C. / min).

[0016] The fly ash hollow microspheres used are 80-120 mesh. The ultrafine slag powder used is 300-400 mesh. The recycled concrete powder used is 100-200 mesh. The desulfurized gypsum used is 100-200 mesh. The calcium carbide slag powder used is 200-300 mesh. The wood ash powder used is 200-300 mesh. The red mud powder used is 200-300 mesh.

[0017] The preparation method of the self-excited geopolymer anti-corrosion coating comprises the following steps: dry-mixing modified fly ash hollow microspheres, ultrafine slag powder, recycled concrete powder, desulfurized gypsum, activated red mud powder, calcium carbide slag powder, wood ash powder, defoaming agent, and polycarboxylic acid water reducer in proportion, with the dry-mixing speed being 150-200 r / min; subsequently, adding deionized water and continuing stirring for 3-4 minutes, with the stirring speed being 1500-1800 r / min, to obtain the self-excited geopolymer anti-corrosion coating.

[0018] The present invention uses microwave-assisted technology to in-situ grow DTPMP-loaded calcium iron hydrotalcite inside acidified fly ash hollow microspheres, and uses the hydrotalcite in a geopolymer anti-corrosion coating, thereby improving the effect of the geopolymer anti-corrosion coating in replacing harmful ions and enhancing its corrosion resistance. Simultaneously, activated red mud powder, carbide slag powder, and wood ash powder, when in contact with water, can form a ternary alkaline environment rich in Ca(OH), Na(OH), and Ka(OH), thereby stimulating aluminosilicate precursors to undergo a more complete geopolymerization reaction. Furthermore, the filling effect of recycled concrete micropowder and fly ash hollow microspheres is utilized to reduce the autogenous shrinkage rate of early self-excited geopolymers, thereby preventing harmful substances from directly corroding the substrate through cracks.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] 1. The application uses fly ash hollow microspheres as the carrier of hydrotalcite, and through the good dispersibility of fly ash hollow microspheres, the agglomeration of hydrotalcite in the geopolymer anti-corrosion coating is avoided. At the same time, under the coating of fly ash hollow microspheres, the displacement reaction of Cl - , SO4 2- , CO3 2- , etc. existing in the early hydration process of hydrotalcite and geopolymer coating is reduced, and the ability of the hardened geopolymer anti-corrosion coating to displace harmful ions such as Cl - , SO4 2- is effectively ensured.

[0021] 2. The application uses microwave-assisted technology to in-situ grow calcium-iron hydrotalcite loaded with corrosion inhibitor DTPMP inside the acidized fly ash hollow microspheres. The electromagnetic waves directly act on the ions in the solution, the heating rate is high and the heating is uniform, which effectively improves the problems of long time consumption, complex technology and high cost existing in the traditional hydrothermal synthesis of hydrotalcite, and helps to quickly synthesize smaller and more uniform hydrotalcite nanocrystals, greatly improving the synthesis rate of hydrotalcite. At the same time, DTPMP is a green corrosion inhibitor as an organic phosphonate compound, and the phosphonic acid group has strong affinity for the steel surface, which can form a two-dimensional monomolecular phosphonate film on the steel surface through chemical or physical adsorption, thereby blocking the corrosion of corrosive media. The loaded DTPMP in the application can be released during use, showing good corrosion protection ability, thereby improving the corrosion resistance of the geopolymer anti-corrosion coating.

[0022] 3. In the application, the activated red mud powder, calcium carbide slag powder and wood ash powder form a ternary alkaline environment rich in Ca(OH), Na(OH) and Ka(OH) when they come into contact with water, which can effectively accelerate the dissolution and re-polymerization of silicate and aluminate precursors, produce more C-A-S-H, C-S-H and N-A-S-H gel, thereby improving the hardness of the self-activated geopolymer coating and forming a dense and strong protective layer. At the same time, due to the filling effect of the recycled concrete micro-powder and fly ash hollow microspheres, the early self-shrinkage rate of the self-activated geopolymer is reduced, and the direct corrosion of harmful substances through cracks is avoided.

[0023] 4. The cementitious material of the application is derived from industrial solid waste, construction waste and biomass combustion ash, and uses an environmentally friendly and cost-effective production method. No additional alkaline activator is needed, and hardening can be completed by simply mixing with water, greatly simplifying the construction process and being conducive to long-term storage and transportation of the material. At the same time, the application reduces environmental pollution and avoids potential harm to construction personnel during the construction process, further demonstrating the advantages of green environmental protection. DETAILED DESCRIPTION

[0024] A self-activated geopolymer anticorrosive coating, raw materials used in the coating include, by weight: modified fly ash hollow microsphere 20-30 parts, superfine slag powder 30-40 parts, recycled concrete powder 20-30 parts, desulfurization gypsum 10-20 parts, activated red mud powder 5-10 parts, carbide slag powder 10-20 parts, wood ash powder 5-10 parts, polycarboxylic acid water reducer 0.2-0.3 parts, defoaming agent 0.3-0.5 parts, deionized water 50-60 parts.

[0025] The preparation method of the self-activated geopolymer anticorrosive coating comprises the following steps:

[0026] 1) Add fly ash hollow microspheres in deionized water according to the solid-liquid ratio of 1g:10mL, adjust the pH value to 1.5-2 by adding 0.1mol / L hydrochloric acid solution, stir at room temperature for 2h, filter, wash with deionized water for 3 times, and then put into a 60℃ drying box for 4h to obtain pretreated fly ash hollow microspheres;

[0027] 2) Add the pretreated fly ash hollow microspheres in step 1) in deionized water according to the solid-liquid ratio of 1g:10mL, ultrasonic dispersion at a frequency of 20-40KHz for 8-15min, then add calcium nitrate hexahydrate (Ca(NO3)2·6H2O), iron nitrate nonahydrate (Fe(NO3)2·9H2O), diethylene triamine penta (methylene phosphonic acid) (DTPMP) according to the mass ratio of 5:1.2:1.1:0.8, adjust the pH value to 10-11 by adding 0.1mol / L sodium hydroxide solution, and then stir at 46-50℃ for 2h (the heating rate is 6.0-6.8℃ / min), and then transfer to a vacuum box for 1h to obtain a suspension;

[0028] 3) Microwave treat the suspension obtained in step 2) at 85-90℃ and a power of 450W for 30min, cool at room temperature, filter the suspension, wash with deionized water for 3 times, and then transfer to a 60℃ vacuum drying box for 8h to obtain fly ash hollow microsphere coated modified calcium-iron hydrotalcite, which is modified fly ash hollow microsphere;

[0029] 4) Place the red mud powder in a muffle furnace and calcine at 700℃ for 4h (the heating rate is 5℃ / min) to obtain activated red mud powder;

[0030] 5) Dry mix the modified fly ash hollow microspheres, superfine slag powder, recycled concrete powder, desulfurization gypsum, activated red mud powder, carbide slag powder, wood ash powder, defoaming agent, and polycarboxylic acid water reducer according to the proportion, the dry mixing speed is 150-200r / min; then, add deionized water and continue to stir for 3-4min, the stirring speed is 1500-1800r / min, to obtain a self-activated geopolymer anticorrosive coating.

[0031] The application provides a self-activated geopolymer anticorrosive coating and a preparation method thereof. In order to further illustrate the technical means and effects adopted by the application, the application is described in detail below in combination with specific embodiments.

[0032] The fly ash hollow microsphere used has a size of 80-120 meshes; the superfine slag powder has a size of 300-400 meshes; the recycled concrete micro powder has a size of 100-200 meshes; the desulfurization gypsum has a size of 100-200 meshes; the carbide slag powder has a size of 200-300 meshes; the wood ash powder has a size of 200-300 meshes; and the red mud powder has a size of 200-300 meshes. Embodiment

[0033] In this embodiment, the raw material ratio of the self-activated geopolymer anticorrosive coating is as follows: modified fly ash hollow microsphere 22 parts, recycled concrete micro powder 28 parts, superfine slag powder 35 parts, desulfurization gypsum 15 parts, activated red mud powder 10 parts, carbide slag powder 15 parts, wood ash powder 5 parts, polycarboxylic acid water reducer 0.2 parts, defoaming agent 0.4 parts, and deionized water 60 parts.

[0034] In this embodiment, the preparation method of the self-activated geopolymer anticorrosive coating is performed according to the following steps:

[0035] Step one: add fly ash hollow microspheres in deionized water according to a solid-liquid ratio of 1g:10mL, add 0.1mol / L hydrochloric acid solution to adjust the pH value to 1.5-2, stir for 2h at room temperature, filter, wash with deionized water for 3 times, and then place in a 60℃ drying box for 4h;

[0036] Step two: add the fly ash hollow microspheres dried in step one in deionized water according to a solid-liquid ratio of 1g:10mL, and ultrasonically disperse for 8-15min at a frequency of 20-40KHz, then add Ca(NO3)2·6H2O, Fe(NO3)2·9H2O and DTPMP according to a mass ratio of 5:1.2:1.1:0.8, add 0.1mol / L sodium hydroxide solution to adjust the pH value to 10-11, and then stir for 2h at 46-50℃ (the heating rate is 6.0-6.8℃ / min), and then transfer to a vacuum box for 1h to obtain a suspension;

[0037] Step three: microwave treat the suspension obtained in step two at a microwave power of 450w and a temperature of 85-90℃ for 30min, cool at room temperature, filter the suspension, wash with deionized water for 3 times, and then transfer to a 60℃ vacuum drying box for 8h to obtain fly ash hollow microsphere-coated modified calcium-iron hydrotalcite, i.e., modified fly ash hollow microspheres.

[0038] Step four: the red mud powder is placed in a muffle furnace for calcination at a temperature of 700°C (at a heating rate of 5°C / min) for 4h to obtain the activated red mud powder;

[0039] Step five: the modified fly ash hollow microsphere, the superfine slag powder, the recycled concrete micro powder, the activated red mud powder, the desulfurization gypsum, the carbide slag powder, the wood ash powder, the defoaming agent, and the polycarboxylic acid water reducer are dry-mixed in proportion at a rotation speed of 150-200r / min; then, deionized water is added for continuous stirring for 3-4min at a rotation speed of 1500-1800r / min to obtain a self-activated geopolymer anti-corrosion coating.

[0040] In the comparative example 1, the fly ash hollow microsphere is not modified.

[0041] In this example, the raw material ratio of the self-activated geopolymer coating is as follows: fly ash hollow microsphere 12 parts, DTPMP modified calcium-iron hydrotalcite 10 parts, recycled concrete micro powder 28 parts, superfine slag powder 35 parts, desulfurization gypsum 15 parts, activated red mud powder 10 parts, carbide slag powder 15 parts, wood ash powder 5 parts, polycarboxylic acid water reducer 0.2 parts, defoaming agent 0.4 parts, and deionized water 60 parts.

[0042] In this example, the preparation method of the self-activated geopolymer coating is as follows:

[0043] Step one: Ca(NO3)2·6H2O, Fe(NO3)2·9H2O, and DTPMP are mixed in a mass ratio of 1.2:1.1:0.8, then deionized water is added in a solid-liquid ratio of 1g:10mL, and 0.1mol / L sodium hydroxide solution is added to adjust the pH value to 10-11, and then the mixture is stirred at 46-50°C for 2h (at a heating rate of 6.0-6.8°C / min) to obtain a suspension;

[0044] Step two: the suspension obtained in step one is subjected to microwave treatment at a microwave power of 450w and a temperature of 85-90°C for 30min, and then the suspension is cooled at room temperature, filtered, washed with deionized water for 3 times, and then transferred to a 60°C vacuum drying oven for drying for 8h to obtain DTPMP modified calcium-iron hydrotalcite;

[0045] Step three: the red mud powder is placed in a muffle furnace for calcination at a temperature of 700°C (at a heating rate of 5°C / min) for 4h to obtain the activated red mud powder.

[0046] Step 4: Dry mix fly ash hollow microspheres, ultrafine slag powder, recycled concrete powder, desulfurized gypsum, activated red mud powder, carbide slag powder, wood ash powder, DTPMP-modified calcium iron hydrotalcite, defoamer, and polycarboxylate superplasticizer in appropriate proportions at a speed of 150-200 rpm. Then, add deionized water and continue stirring for 3-4 minutes at a speed of 1500-1800 rpm. This yields a self-excited geopolymer coating.

[0047] Comparative Example 2 does not use microwave technology

[0048] In this embodiment, the raw material ratio of the self-excited geopolymer coating is as follows, by weight: 22 parts of modified fly ash hollow microspheres, 28 parts of recycled concrete powder, 35 parts of ultrafine slag powder, 15 parts of desulfurized gypsum, 10 parts of activated red mud powder, 15 parts of calcium carbide slag powder, 5 parts of wood ash powder, 0.2 parts of polycarboxylic acid water reducer, 0.4 parts of defoaming agent, and 60 parts of deionized water.

[0049] In this embodiment, the preparation method of the self-excited geopolymer coating is carried out according to the following steps:

[0050] Step 1: Add fly ash hollow microspheres to deionized water at a solid-liquid ratio of 1g:10mL, add 0.1mol / L hydrochloric acid solution to adjust the pH value to 1.5-2, stir at room temperature for 2h, filter, rinse with deionized water 3 times, and place in a 60℃ drying oven for 4h;

[0051] Step 2: Add the dried fly ash hollow microspheres obtained in step 1 to deionized water at a solid-liquid ratio of 1 g:10 mL, and ultrasonically disperse them at a frequency of 20~40 kHz for 8~15 minutes. Then, add Ca(NO3)2·6H2O, Fe(NO3)2·9H2O, and DTPMP at a mass ratio of 5:1.2:1.1:0.8, and add 0.1 mol / L sodium hydroxide solution to adjust the pH value to 10-11. Keep stirring at 46~50°C for 2 hours (heating rate of 6.0~6.8°C / min), cool to room temperature, filter, wash with deionized water three times, and then transfer to a 60°C vacuum drying oven and dry for 8 hours to obtain modified fly ash hollow microspheres that have not been microwave treated.

[0052] Step 3: calcining the red mud powder in a muffle furnace at a temperature of 700°C (heating rate of 5°C / min) for 4 hours to obtain activated red mud powder;

[0053] Step four: dry mix modified fly ash cenospheres, superfine slag powder, recycled concrete powder, activated red mud powder, desulfurization gypsum, carbide slag powder, wood ash powder, defoaming agent, polycarboxylic acid water reducer according to the proportion, dry mixing speed is 150~200r / min; then, add deionized water and continue stirring for 3~4min, stirring speed is 1500~1800r / min, to obtain a self-activated geopolymer coating.

[0054] Comparative example 3 does not add DTPMP

[0055] In this embodiment, the raw material ratio of the self-activated geopolymer coating is: modified fly ash cenospheres 22 parts, recycled concrete powder 28 parts, superfine slag powder 35 parts, desulfurization gypsum 15 parts, activated red mud powder 10 parts, carbide slag powder 15 parts, wood ash powder 5 parts, polycarboxylic acid water reducer 0.2 parts, defoaming agent 0.4 parts, deionized water 60 parts.

[0056] In this embodiment, the preparation method of the self-activated geopolymer coating is as follows:

[0057] Step one: add fly ash cenospheres in deionized water according to the solid-liquid ratio of 1g:10mL, add 0.1mol / L hydrochloric acid solution to adjust the pH value to 1.5~2, then stir at room temperature for 2h, filter, wash with deionized water for 3 times, and then put into a 60℃ drying box for 4h;

[0058] Step two: add the fly ash cenospheres dried in step one in deionized water according to the solid-liquid ratio of 1g:10mL, ultrasonic dispersion at a frequency of 20~40KHz for 8~15min, then add Ca(NO3)2·6H2O, Fe(NO3)2·9H2O according to the mass ratio of 5:1.2:1.1, add 0.1mol / L sodium hydroxide solution to adjust the pH value to 10-11, then heat at 46~50℃ for 2h (heating rate is 6.0~6.8℃ / min), then transfer to a vacuum box and place for 1h to obtain a suspension;

[0059] Step three: microwave treat the suspension obtained in step two, microwave power is 450w, temperature is 85~90℃, treatment time is 30min, cool at room temperature, then filter the suspension, wash with deionized water for 3 times, then transfer to a 60℃ vacuum drying box and dry for 8h to obtain modified fly ash cenospheres;

[0060] Step four: calcine the red mud powder in a muffle furnace, calcination temperature is 700℃ (heating rate is 5℃ / min), time is 4h, to obtain activated red mud powder;

[0061] Step five: dry mix the modified fly ash cenospheres, superfine slag powder, recycled concrete powder, desulfurization gypsum, modified red mud powder, carbide slag, wood ash, defoaming agent, and polycarboxylic acid superplasticizer according to the proportion, the dry mixing speed is 150-200 r / min; then, add deionized water and continue to stir for 3-4 min, the stirring speed is 1500-1800 r / min, and a self-activated geopolymer etching coating is obtained.

[0062] The corrosion resistance effect of the coating is determined by the following method, and the results are shown in Table 1:

[0063] (1) The coating is uniformly distributed on the surface of the steel bar by spraying or dipping. After curing for 7 days in an environment with a temperature of 20°C and a humidity of 60-70%, the coated steel bar is placed in simulated seawater for accelerated corrosion with an applied voltage of 26V for 1 hour. After corrosion, the corrosion current density and rust inhibition rate of the coated steel bar are tested by an electrochemical workstation.

[0064] The rust inhibition rate (R) is calculated by the following formula: or

[0065]

[0066] Wherein, I0 is the current density of the uncoated steel bar, and I is the current density of the coated steel bar. corr,0 corr

[0067] (2) The coating is uniformly applied on the surface of the concrete test block by spraying or brushing, and the thickness of the coating is 1±0.1 mm. The size of the concrete test block is 100 mm in diameter and 50 mm in height. After curing for one week in an environment with a temperature of 20°C and a humidity of 95%, the concrete test block coated with the coating is tested for rapid chloride ion permeability according to the national standard GB / T50082-2024 "Standard for Testing Methods for Long-term Performance and Durability of Concrete".

[0068] (3) After curing the coating in an environment with a temperature of 20°C and a humidity of 95% for 7 days, the coating is crushed, dried, and sieved with a 100 mesh sieve to obtain a dry coating powder. The dry coating powder is added to a 0.1 mol / L sodium chloride solution at a solid-liquid ratio of 1g:5ml, and the chloride ion adsorption is carried out at a temperature of 20°C. After 7 days, the chloride ion content of the obtained filtrate is tested.

[0069] Table 1

[0070]

[0071] ​​​​As shown in Table 1, the rust inhibition rate of the coated rebar in the example reaches 97.5%, which is obviously higher than that of the comparative example, indicating that the coating prepared in the example can provide better corrosion protection for the rebar. Meanwhile, the chloride ion penetration depth in the example is only 0.5 mm, while the chloride ion penetration depth in the comparative example is >1.8 mm, indicating that the coating in the example can completely fix the chloride ions inside the coating, thus having better resistance to chloride ion penetration. The chloride ion adsorption amount of the dry powder coating in the example is 5.83 mg / g, which exhibits excellent chloride ion adsorption level.

[0072] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent changes and modifications within the technical range disclosed in the present application, which shall fall within the protection scope of the present application.

Claims

1. A self-excited geopolymer anti-corrosion coating, characterized by: The raw materials used include, by weight: 20-30 parts of modified fly ash hollow microspheres, 30-40 parts of ultrafine slag powder, 20-30 parts of recycled concrete powder, 10-20 parts of desulfurized gypsum, 5-10 parts of activated red mud powder, 10-20 parts of calcium carbide slag powder, 5-10 parts of wood ash powder, 0.2-0.3 parts of polycarboxylate water reducer, 0.3-0.5 parts of defoaming agent, and 50-60 parts of deionized water; The modified fly ash hollow microspheres are specifically fly ash hollow microspheres coated with modified calcium iron hydrotalcite; the preparation thereof comprises the following steps: 1) Fly ash hollow microspheres were added to deionized water at a solid-liquid ratio of 1 g:10 mL, the pH value was adjusted to 1.5-2, and the mixture was stirred at room temperature for 2 h, filtered, washed three times with deionized water, and dried at 60°C for 4 h to obtain pretreated fly ash hollow microspheres; 2) Add the fly ash hollow microspheres pretreated in step 1) to deionized water at a solid-liquid ratio of 1 g:10 mL. After ultrasonic dispersion, add calcium nitrate hexahydrate, ferric nitrate nonahydrate, and diethylenetriamine penta (methylene phosphonic acid). Adjust the pH to 10-11, maintain stirring at 46-50°C for 2 h, and then transfer to a vacuum chamber for 1 h to obtain a suspension. 3) The suspension obtained in step 2) was subjected to microwave treatment, and then cooled at room temperature and filtered, washed with deionized water three times, and then dried at 60° C. for 8 h to obtain fly ash hollow microspheres coated with modified calcium iron hydrotalcite.

2. The self-excited geopolymer anti-corrosion coating according to claim 1, characterized in that: The frequency of the ultrasonic dispersion in step 2) is 20-40 kHz, and the time is 8-15 minutes.

3. The self-excited geopolymer anti-corrosion coating according to claim 1, characterized in that: The mass ratio of the pretreated fly ash hollow microspheres, calcium nitrate hexahydrate, ferric nitrate nonahydrate and diethylenetriamine penta (methylene phosphonic acid) used in step 2) is 5:1.2:1.1:0.

8.

4. The self-excited geopolymer anti-corrosion coating according to claim 1, characterized in that: The microwave treatment in step 3) is performed at a temperature of 85-90° C., a power of 450 W, and a time of 30 min.

5. The self-excited geopolymer anti-corrosion coating according to claim 1, characterized in that: The activated red mud powder is prepared by placing the red mud powder in a muffle furnace and calcining it at 700° C. for 4 hours.

6. A method for preparing the self-excited geopolymer anti-corrosion coating according to claim 1, characterized in that: Modified fly ash hollow microspheres, ultrafine slag powder, recycled concrete powder, desulfurized gypsum, activated red mud powder, carbide slag powder, wood ash powder, defoamer, and polycarboxylate water reducer are dry-mixed in proportion; then, deionized water is added and stirring is continued for 3 to 4 minutes to obtain the self-excited geopolymer anti-corrosion coating.

7. The method for preparing the self-excited geopolymer anti-corrosion coating according to claim 6, characterized in that: The rotation speed of the dry mixing is 150~200r / min; the rotation speed of the stirring is 1500~1800r / min.

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