Coated slow-release medium transmission inhibitor as well as preparation method and application thereof

Abstract

The invention discloses a coated slow-release medium transmission inhibitor as well as a preparation method and application thereof, and belongs to the technical field of building material admixtures. The coated slow-release medium transmission inhibitor is prepared from the following raw materials: a pore compacting component, a pore film forming component, a particle coating component, a dispersing component and a mineral admixture, wherein the pore compacting component is a compacting filler; the pore film forming component is redispersible rubber powder; the particle coating component is a lipophilic organic matter with the vaporization temperature of 60-300 DEG C; the particle coating component uniformly and compactly coats the surfaces of the pore compacting component and the pore film forming component. The coated slow-release medium transmission inhibitor can be applied to reinforced concrete structures of tunnels, mines, sewage treatment, pipeline corrosion prevention, municipal engineering, energy engineering and the like in water-rich or salt-rich environments, is used for inhibiting transmission of corrosive media into concrete, and has a remarkable inhibiting effect on dissolution of calcium ions in the concrete.

Description

Technical Field

[0001] The present invention belongs to the technical field of building material admixtures, and particularly relates to a coated slow-release medium transmission inhibitor, a preparation method and an application thereof. Background Art

[0002] For reinforced concrete projects in underground structures for a long time, such as tunnels, mines, municipal, energy and sewage treatment projects, etc., the reinforced concrete structure will inevitably be eroded by groundwater or sewage for a long time, resulting in prominent problems such as underground structure leakage and corrosion damage. Corrosive media will penetrate into the concrete interior along with water, causing concrete corrosion damage; calcium ions in the concrete will also dissolve out with groundwater, causing leakage. It is estimated that about 90% of tunnels around the world will have leakage problems. Due to characteristics such as a large water-binder ratio, high cement dosage, and fast setting time, the primary support concrete of tunnels in a water-rich environment is prone to calcium ion dissolution and precipitation, resulting in concrete damage and deterioration. Its deterioration mechanism is that unhydrated cement and soluble cement hydration products are washed out by flowing water to precipitate calcium ions, and under the action of the concentration difference inside and outside, they migrate into the environment, gradually increasing the porosity and decreasing the strength of the primary support concrete. Further, the dissolution of hydration products leads to a decrease in the pH of the pore fluid, increasing the risk of steel arch corrosion. At the same time, a large amount of calcium ions precipitate and react in the tunnel drainage system to form calcium carbonate crystals, clogging the drain pipes (ditches), resulting in slippery tunnel pavements and damaged electrical appliances, thus endangering the driving safety and structural durability of the long-term operation of the tunnel.

[0003] Currently, there have been studies on improving the resistance of concrete to medium transmission and calcium ion dissolution, mainly including methods such as reducing the water-binder ratio, adding mineral admixtures, and enhancing hydrophobicity. The research results of Yu et al. (Construction Building Materials, 2018, 161: 509-518) show that compared with concrete specimens with a water-binder ratio of 0.5, the mass loss, calcium hydroxide dissolution amount, and porosity of concrete with a water-binder ratio reduced to 0.35 have been significantly improved. However, for the convenience of shotcrete construction, the water-binder ratio of the primary support concrete of tunnels is generally relatively high, and reducing the water-binder ratio will affect the construction performance of the concrete. Existing research shows that adding mineral admixtures can reduce Ca(OH) in the hydration products 2The amount of [material] refines the pores of concrete and improves its anti-corrosion performance. Han (Construction & Building Materials, 2014, 68 (oct. 15): 630 - 636) et al. studied the effects of fly ash and slag on the anti-corrosion performance of concrete. The results showed that when the fly ash content was less than 65% (mass fraction), the concrete had good anti-corrosion performance. When the slag content was less than 70% (mass fraction), the concrete showed good long-term anti-corrosion performance. The research by Wolfram et al. (Cement & Concrete Composites, 2015) showed that reducing the water-binder ratio and adding fly ash and slag could improve the anti-corrosion performance of concrete, where the fly ash content was not more than 40% (mass fraction) and the slag content was not more than 70% (mass fraction). However, due to the low degree of hydration of the cementitious system, the early strength of the primary support concrete would decrease, and at the same time, the setting time would be prolonged, thus having an adverse impact on tunnel construction. Materials that improve the compactness of concrete include not only mineral admixtures but also nanomaterials, etc. Common nanomaterials mainly include nano-silica, nano-titanium dioxide, and nano-calcium carbonate, etc. Jalal et al. (Materials and Design, 2012, 34: 389 - 400.) studied the effects of nano-silica on the properties of self-compacting concrete. The results showed that after adding nano-silica, the pore structure of the concrete became more refined and dense, and the concrete strength increased, but the inhibitory effect on medium transmission was relatively limited.

[0004] Patent CN108129052 B discloses an application of fatty acid esters as anti-rainwater erosion additives for permeable concrete and an anti-rainwater erosion additive for permeable concrete. The fatty acid esters are long-chain organic carboxylic acid esters. Through the strong alkalinity of the concrete, they can be hydrolyzed to release organic carboxylic acids and react with calcium ions in the hydration products to form calcium fatty acid hydrophobic substances, thereby enhancing the anti-rainwater erosion performance of permeable concrete. And anti-rainwater erosion additives are prepared according to different functional components. In the invention, due to the poor hydrophilicity of the fatty acid esters, it affects the dispersion of effective components during the concrete mixing process. At the same time, the calcium carboxylate formed by the reaction of the long-chain hydrophobic substances has a negative impact on the microstructure and mechanical properties of the concrete, thus affecting the actual application effect. CN114890734A discloses an anti-calcium erosion cement-based material for concrete, which is prepared by mixing two-component materials with water. This invention material inhibits the dissolution of calcium ions by brushing the surface of the concrete after mixing, and has the advantages of good workability, high strength, good compatibility with the matrix, fast setting and hardening speed, low calcium dissolution degree in soft water, not easy to peel off, convenient transportation, and low price. Nevertheless, existing anti-medium transmission inhibition technologies still have problems in anti-erosion engineering applications, such as the anti-erosion effect is not significant enough, the directly added nanomaterials affect the workability of the concrete and are not convenient for construction, some admixtures have a great impact on the work and mechanical properties of the concrete, especially the calcium ion dissolution inhibition performance of the concrete is still not ideal; in addition, in water-rich or salt-rich environments, the corrosion and damage of the concrete's own structure caused by water flow scouring and salt erosion are greatly aggravated, which is more likely to cause the dissolution of calcium ions in the concrete, and this also brings new challenges to the anti-calcium ion erosion of the concrete. Summary of the Invention

[0005] In order to better improve the anti-medium transmission and anti-calcium ion erosion performance of concrete, enhance the long-term corrosion resistance of concrete, especially the anti-calcium ion dissolution performance in water-rich or salt-rich environments, the present invention provides a coated slow-release medium transmission inhibitor, a preparation method and an application, and applies this inhibitor to the reinforced concrete structures of tunnels, mines, sewage treatment, pipeline anti-corrosion and municipal, energy and other projects in water-rich or salt-rich environments to inhibit the transmission of corrosive media into the concrete, and at the same time has a significant inhibitory effect on the dissolution of calcium ions in the concrete.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A coated slow-release medium transmission inhibitor, the preparation raw materials of which include the following components according to mass percentage:

[0008] Pore dense component…………………………10% - 50%,

[0009] Pore film-forming component…………………………10% - 30%,

[0010] The particle coating component…………………………0.5% - 10%,

[0011] The dispersion component………………………………0.1% - 5%,

[0012] The balance is mineral admixture;

[0013] The pore densification component is a dense filler; the pore film - forming component is redispersible polymer powder; the particle coating component is a lipophilic organic compound with a vaporization temperature of 60 - 300°C; the particle coating component uniformly and densely coats the surfaces of the pore densification component and the pore film - forming component.

[0014] Preferably, the particle coating component can be vaporized and then coat the surfaces of the pore densification component and the pore film - forming component to form a uniform and dense protective film, so as to achieve the slow release of the dense filler and the redispersible polymer powder and the long - term effect of inhibiting calcium ion dissolution.

[0015] Preferably, both the pore densification component and the pore film - forming component coated with the particle coating component are in a spherical or quasi - spherical structure; the spherical or quasi - spherical structure is more conducive to the application of powder particles in the concrete system. It not only does not affect the fluidity of the concrete, but also can appropriately improve the mechanical properties of the concrete.

[0016] Preferably, in the preparation raw materials of the coated slow - release medium transmission inhibitor, the percentage mass ratio of the particle coating component is 0.5% - 3.5%. The material composition and dosage of the particle coating component are closely related to the thickness and compactness of the coating film layer, and are also closely related to the release process after participating in cement hydration later. Generally, the higher the percentage mass ratio of the coating component, the thicker and more compact the coating film layer on the particle surface. However, an overly thick coating film layer is not conducive to the later release of the densification and film - forming components. And the lower the percentage mass ratio, the thinner the coating film layer, and it will also be released earlier in the strong alkaline environment of the cement - based material, resulting in incomplete cement hydration and affecting the compactness of the hydration product structure and the long - term anti - medium erosion performance.

[0017] Optionally, the dense filler is one or a combination of solid particles such as silica fume, densified silica fume, nano - silica, nano - calcium carbonate, nano - titanium dioxide, etc.; further, the specific surface area of the silica fume and the densified silica fume is 20000 - 25000m 2 / kg. The particle sizes of the nano-silica, nano-calcium carbonate, and nano-titanium dioxide are between 10 and 1000 nm, and more preferably between 10 and 500 nm. In addition to the composition and structure of the nano-particles themselves having a great influence on the pore density of concrete, the size of the nano-particle diameter also has a significant impact on the pore structure and the interfacial transition zone of concrete. The optimization of pore density and the interfacial transition zone has a huge impact on the improvement of anti-medium permeability. In the present invention, the nano-particle diameter is preferably selected by comparison. At the same time, according to different concrete mixing systems, the types, particle diameters, and compositions of nano-materials can be selectively matched, so as to achieve better anti-medium permeability performance.

[0018] Preferably, the redispersible powder includes, but is not limited to, VAE powder, styrene-based powder, etc. This type of redispersible powder has good compatibility with the strong alkaline system of cement-based materials, can participate in the cement hydration process, and can be evenly distributed on the surface of hydration products. After being released in a strong alkali and strong salt system, it has the characteristics of rapid dissolution, high-efficiency dispersion, and uniform distribution, so as to more efficiently improve the stability of the hydration products themselves and effectively inhibit the dissolution rate of calcium ions in the hydration products under a strong penetration medium system.

[0019] Preferably, the lipophilic organic matter specifically includes, but is not limited to, one or several combinations of paraffin, stearic acid, organosiloxane, etc. Coating materials with similar performance characteristics can also be applied. The coating material has the characteristic of vaporizing into a film. Moreover, through the regulation of the vaporization film-forming temperature, the percentage mass content of the film-forming substance, and the mixing process, the uniform denseness of the film formed on the surface of the coated particles and the regulation of the coating film thickness can be achieved, so as to realize the slow release of the coated particles and avoid the premature participation of the particle densification and film-forming components in the cement hydration, which affects the structure and pore density of the hydration products.

[0020] Preferably, the dispersing component is a powder-type water reducer, including, but is not limited to, one or several combinations of naphthalene-based, melamine-based, and polycarboxylate-based water reducers.

[0021] Preferably, the mineral admixture is one or several combinations of fly ash, slag powder, and stone powder.

[0022] On the other hand, the present invention also provides a preparation method of the coated slow-release medium transmission inhibitor, which specifically includes the following steps:

[0023] (1) Add the pore-dense component and the pore-forming film component into the mixer. After stirring evenly, heat up the temperature in the mixer to 60 - 300 °C, and slowly add the vaporized particle coating component. Control the temperature in the mixer so that the added particle coating component remains in a vaporized state, and through the mixing process of the materials, make the lipophilic organic matter form a uniform adsorption on the surface of the solid powder particles. Then slowly lower the temperature so that the vaporized film adsorbed on the particle surface gradually solidifies and forms, thus forming a uniform and stable coating film;

[0024] (2) Lower the temperature in the mixer to below 60 °C, add the dispersion component and the mineral admixture into the mixer, continue to mix evenly and then discharge, thus obtaining the coated slow-release medium transmission inhibitor.

[0025] The preparation process of the coated slow-release medium transmission inhibitor described in the present invention includes several processes such as the mixing of the dense filler and the redispersible rubber powder, surface coating, and the mixing with the dispersion component and the mineral admixture. The powder mixing process is carried out in the mixer; the coating process vaporizes the coating material through the heating process, adds it into the mixer through the vaporization atomization device, and is evenly distributed in the mixer at a relatively high temperature. Through the adsorption on the surface of the dense filler and the redispersible rubber powder, a coating film layer is formed, and then through means such as gradually lowering the temperature, the coating material is finally solidified on the particle surface, thus realizing the uniform coating of the particles. Gradually lowering the temperature can be achieved by air cooling or liquid cooling means, and is controlled by the process equipment. The cooling process can be selected and optimized according to the different characteristics of the coating material.

[0026] On the other hand, the present invention also provides the application of the coated slow-release medium transmission inhibitor. The coated slow-release medium transmission inhibitor can be applied to the reinforced concrete structures of tunnels, sewage treatment, pipeline anti-corrosion, and municipal and energy projects in water-rich or salt-rich environments to inhibit the transmission of corrosive media and the dissolution of calcium ions in concrete; the coated slow-release medium transmission inhibitor is incorporated during the concrete mixing process, and the incorporation amount is 5% - 10% of the amount of the cementitious material; the coated slow-release medium transmission inhibitor is added during the concrete mixing process, and the mixing time during the mixing process can be appropriately extended by 30 s - 1 min to ensure the full mixing of the calcium ion corrosion inhibitor and the concrete mixture. At the same time, strictly control the water consumption of the concrete to ensure that the concrete added with the calcium ion corrosion inhibitor is mixed according to the designed ratio.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The coated slow-release medium transmission inhibitor includes a pore-compacting component and a pore-filming component. The pore-compacting component can fill the pores of the hydration products during the hydration process, enhancing the self-compactness of the concrete; the pore-filming component can form an organic film layer inside the pores during the hydration process, and this film layer can effectively inhibit the action of water and other corrosive salt media on the cement hydration products, thereby reducing the dissolution rate of calcium ions and the corrosion rate in the cement hydration products. Through the synergistic effect of pore compaction and pore internal filming in the concrete, the effect of enhancing the resistance of concrete to calcium ion dissolution can be effectively achieved.

[0029] (2) In addition, the coated slow-release medium transmission inhibitor of the present invention also performs surface modification treatment on the pore-compacting component and the pore-filming component through a special vaporization treatment preparation process. After surface treatment, it can slow down the direct action of the pore-compacting component and the pore-filming component with the hydration products in the early stage of cement hydration, thereby avoiding the influence of the pore-compacting component and the pore-filming component on the workability and early mechanical properties of the concrete; after surface coating treatment, as the cement hydration progresses, the pore-compacting component and the pore-filming component are gradually released, and then fill the pores inside the concrete after relatively complete hydration and perform pore internal filming modification, so as to better achieve the effects of concrete performance development, long-term resistance to medium transmission, and corrosion inhibition.

[0030] (3) Furthermore, the coated slow-release medium transmission inhibitor of the present invention is processed by a special vaporization process. The functional components include particles of different sizes and dispersing components, including but not limited to nanoparticles and other powder particles. By combining dense particles of different sizes, the compactness of the hydration products can be optimized and enhanced, thereby better achieving the effects of medium transmission inhibition and calcium ion corrosion inhibition. Detailed implementation mode

[0031] The following examples describe in more detail the preparation of the powder particle-coated slow-release medium transmission inhibitor according to the method of the present invention, and these examples are given in an illustrative manner, aiming to enable those familiar with this technology to understand the content of the present invention and implement it accordingly, but these examples in no way limit the scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0032] The parts of each raw material in each example and comparative example are all parts by mass. Among them, the naphthalene-based and polycarboxylate dispersants are both produced by Jiangsu Sobute New Materials Co., Ltd., with models JM-A and PCA-I respectively, and the powdered melamine water reducer is produced by BASF, with model F-15. The dispersants described in the present invention are not limited to the above manufacturers and models, and other dispersants with the same functions can also be used as the materials for the examples.

[0033] Example 1

[0034] Add 50 parts of silica fume with a specific surface area of 23,500 m 2 / kg and 15 parts of VAE latex into the mixer. Stir for 30 min in the mixer. After stirring evenly, heat the mixer to 220 °C. Vaporize 5 parts of paraffin liquid through the spraying device and introduce it into the mixer. At a temperature of 120 °C, continue to mix the powder material and the vaporized paraffin. After mixing for 30 min, start to cool down, so that the vaporized paraffin is fully adsorbed on the surface of the powder particles and gradually forms a coating film layer. When the temperature drops to 50 °C, add 4.5 parts of powdered naphthalene-based water reducer and 25.5 parts of fly ash into the mixer, and continue to mix for 40 min. After mixing evenly, discharge to obtain the powder particle-coated slow-release medium transmission inhibitor S1.

[0035] Example 2

[0036] Add 37 parts of silica fume with a specific surface area of 20,000 m 2 / kg and 30 parts of VAE latex into the mixer. Stir for 30 min in the mixer. After stirring evenly, heat the mixer to 250 °C. Vaporize 3 parts of stearic acid liquid through the spraying device and introduce it into the mixer. At a temperature of 250 °C, continue to mix the powder material and the vaporized stearic acid. After mixing for 30 min, start to cool down, so that the vaporized stearic acid is fully adsorbed on the surface of the powder particles and gradually forms a coating film layer. When the temperature drops to 40 °C, add 3 parts of powdered polycarboxylate water reducer and 27 parts of mineral powder into the mixer, and continue to mix for 50 min. After mixing evenly, discharge to obtain the powder particle-coated slow-release medium transmission inhibitor S2.

[0037] Example 3

[0038] Add 20 parts of nano-silica with a particle size of 50 nm and 20 parts of styrene-butadiene resin powder into the mixer. Stir for 40 min in the mixer. After stirring evenly, heat the mixer to 150 °C. Vaporize 3 parts of dodecyltriethylsiloxane liquid through the spraying device and introduce it into the mixer. At a temperature of 250 °C, continue to mix the powder material and the vaporized dodecyltriethoxysilane. After mixing for 40 min, start to cool down, so that the vaporized dodecyltriethylsiloxane is fully adsorbed on the surface of the powder particles and gradually forms a coating film layer. When the temperature drops to 30 °C, add 2.5 parts of powdered melamine water reducer, 24.5 parts of mineral powder and 30 parts of fly ash into the mixer, and continue to mix for 30 min. After mixing evenly, discharge to obtain the powder particle-coated slow-release medium transmission inhibitor S3.

[0039] Example 4

[0040] Add 20 parts of nano-silica with a particle size of 15 nm and 20 parts with a specific surface area of 25,000 m 225 parts of encrypted silica fume and VAE latex powder per kg were added to a mixer and stirred for 50 min. After stirring evenly, the mixer was heated to 200 °C. 3.5 parts of liquid paraffin were vaporized through a spraying device and introduced into the mixer. At a temperature of 250 °C, the powder material and the vaporized paraffin steam were continuously mixed. After mixing for 30 min, the temperature was decreased, so that the vaporized paraffin was fully adsorbed on the surface of the powder particles and gradually formed a coating film layer. When the temperature decreased to 30 °C, 3.5 parts of powdered melamine water reducer and 27.5 parts of stone powder were added to the mixer, and mixing continued for 60 min. After mixing evenly, the mixture was discharged to obtain the powder particle-coated slow-release medium transmission inhibitor S4.

[0041] Example 5

[0042] 15 parts of nano-titanium dioxide with a particle size of 100 nm and 20 parts of VAE latex powder were added to a mixer and stirred for 30 min. After stirring evenly, the mixer was heated to 280 °C. 1 part of stearic acid was liquefied through a spraying device and introduced into the mixer. At a temperature of 280 °C, the powder material and the vaporized stearic acid steam were continuously mixed. After mixing for 30 min, the temperature was decreased, so that the vaporized stearic acid was fully adsorbed on the surface of the powder particles and gradually formed a coating film layer. When the temperature decreased to 40 °C, 0.5 part of powdered polycarboxylate water reducer, 43.5 parts of fly ash and 20 parts of mineral powder were added to the mixer, and mixing continued for 60 min. After mixing evenly, the mixture was discharged to obtain the powder particle-coated slow-release medium transmission inhibitor S5.

[0043] Example 6

[0044] 25 parts of nano-calcium carbonate with a particle size of 500 nm and 10 parts of Taichung ABS high rubber powder were added to a mixer and stirred for 50 min. After stirring evenly, the mixer was heated to 180 °C. 2.5 parts of lauric acid were liquefied through a spraying device and introduced into the mixer. At a temperature of 180 °C, the powder material and the vaporized lauric acid steam were continuously mixed. After mixing for 30 min, the temperature was decreased, so that the vaporized lauric acid was fully adsorbed on the surface of the powder particles and gradually formed a coating film layer. When the temperature decreased to 40 °C, 1 part of powdered polycarboxylate water reducer, 30 parts of fly ash and 31.5 parts of stone powder were added to the mixer, and mixing continued for 30 min. After mixing evenly, the mixture was discharged to obtain the powder particle-coated slow-release medium transmission inhibitor S6.

[0045] Comparative Example 1

[0046] This comparative example was set based on Example 2. The difference was that the pore-dense component was not coated, and other conditions were the same as those in Example 2.

[0047] Add 30 parts of VAE latex to the mixer, stir in the mixer for 30 min. After stirring evenly, heat the mixer to 250 °C. Vaporize 3 parts of stearic acid liquid through the spraying device and introduce it into the mixer. At the temperature of 250 °C, continue to mix the powder material and vaporized stearic acid. After mixing for 30 min, start to cool down, so that the vaporized stearic acid is fully adsorbed on the surface of the powder particles and gradually forms a coating film layer. When the temperature drops to 40 °C, add 37 parts of silica fume with a specific surface area of 20,000 m 2 / kg, 3 parts of powdered polycarboxylate superplasticizer and 27 parts of mineral powder into the mixer, continue to mix for 50 min, and discharge after mixing evenly to obtain the powder particle coated slow-release medium transport inhibitor D1

[0048] Comparative Example 2

[0049] This comparative example is set based on Example 2. The difference is that the pore-forming film component is not coated, and other conditions are the same as those in Example 2.

[0050] Add 37 parts of silica fume with a specific surface area of 20,000 m 2 / kg to the mixer, stir in the mixer for 30 min. After stirring evenly, heat the mixer to 250 °C. Vaporize 3 parts of stearic acid liquid through the spraying device and introduce it into the mixer. At the temperature of 250 °C, continue to mix the powder material and vaporized stearic acid. After mixing for 30 min, start to cool down, so that the vaporized stearic acid is fully adsorbed on the surface of the powder particles and gradually forms a coating film layer. When the temperature drops to 40 °C, add 30 parts of VAE latex, 3 parts of powdered polycarboxylate superplasticizer and 27 parts of mineral powder into the mixer, continue to mix for 50 min, and discharge after mixing evenly to obtain the powder particle coated slow-release medium transport inhibitor D2.

[0051] Comparative Example 3

[0052] This comparative example is set based on Example 2. The difference is that the particle coating component is not vaporized, and other conditions are the same as those in Example 2.

[0053] Add 37 parts of silica fume with a specific surface area of 20,000 m 2 / kg and 30 parts of VAE latex to the mixer, stir in the mixer for 30 min. After stirring evenly, introduce 3 parts of stearic acid liquid into the mixer, continue to mix the powder material and paraffin for 30 min, so that the paraffin is adsorbed on the surface of the powder particles. Raise the temperature to 40 °C, add 3 parts of powdered polycarboxylate superplasticizer and 27 parts of mineral powder into the mixer, continue to mix for 50 min, and discharge after mixing evenly to obtain the powder particle coated slow-release medium transport inhibitor D3.

[0054] Application Example

[0055] The coated slow-release medium transmission inhibitor of the present invention is mainly applied to the reinforced concrete structures of tunnels, mines, sewage treatment, pipeline anti-corrosion, and municipal and energy projects in water-rich or salt-rich environments, used to inhibit the transmission of corrosive media into the concrete, and at the same time has a significant inhibitory effect on the dissolution of calcium ions in the concrete. The coated slow-release medium transmission inhibitor is incorporated during the concrete mixing process, and the incorporation dosage is 5% - 10% relative to the dosage of the cementitious material. During the mixing process, the mixing time can be appropriately extended by 30s - 1min to ensure the full mixing of the medium transmission inhibitor and the concrete mixture. At the same time, strictly control the water consumption of the concrete to ensure that the concrete added with the medium transmission inhibitor is mixed according to the designed ratio.

[0056] Taking the application of the corrosion-resistant structure concrete in the tunnel as an example, the anti-corrosion materials are applied to the shotcrete, and the dissolution of calcium ions in the shotcrete is inhibited by the coated slow-release medium transmission inhibitor. The selected raw materials include Portland cement (PO 42.5), large stones (basalt 10 - 20mm), river sand (medium sand), accelerating agent (alkali-free liquid), inhibitor (different samples of the coated slow-release medium transmission inhibitor prepared in the examples of the present invention). The concrete mix proportion is shown in Table 1. To ensure the same water-binder ratio, when adding the powder-coated slow-release medium transmission inhibitor, the dosage of Portland cement is deducted equally. In order to better compare the inhibitory effect of the present invention on the dissolution of calcium ions in the tunnel structure concrete, the commonly used dense silica fume (SF) and the samples of Comparative Examples 1 - 3 (D1 - D3) are selected as the comparative samples.

[0057] Table 1 Concrete mix proportion (kg / m 3 )

[0058]

[0059] Mold the concrete and study the effects of different comparative samples and the samples prepared by the present invention on the sulfate corrosion resistance, chloride ion penetration resistance, and calcium ion dissolution of the concrete, etc. Among them, the test methods for the sulfate corrosion resistance coefficient and chloride ion diffusion coefficient refer to the test methods specified in GB / T 50082-2009 "Standard Test Methods for Long-Term Performance and Durability of Ordinary Concrete". The calcium ion dissolution rate of the anti-corrosion performance is tested by the immersion method, which is the ratio of the calcium ion dissolution amount after 14d of immersion to the total calcium ion amount of the concrete. The experimental results are shown in Table 2.

[0060] Table 2 Concrete anti-medium penetration and calcium ion dissolution performance (kg / m 3 )

[0061]

[0062]

[0063] The experimental results in Table 2 show that SF, D1, D2, D3 and the coated slow-release medium transport inhibitor prepared by the present invention all have relatively significant effects on inhibiting sulfate corrosion, reducing the chloride ion diffusion coefficient and reducing the calcium ion dissolution rate. Among them, the sample prepared by the present invention has a more excellent improvement effect on various corrosion resistance performances. Moreover, after surface coating, the influence of the nano-dense and film-forming materials on the working and mechanical properties of concrete is also greatly reduced, especially showing excellent effects in reducing the chloride ion diffusion coefficient and calcium ion dissolution rate. The reduction of the chloride ion diffusion coefficient and calcium ion dissolution rate further highlights the improvement and enhancement of the long-term anti-corrosion performance of concrete by this technology.

Claims

1. A coated slow-release medium transmission inhibitor, characterized in that, its preparation raw materials include the following components by mass percentage: Pore-dense component ………………………… 10% - 50%, Pore-forming film component ………………………… 10% - 30%, Particle coating component ………………………… 0.5% - 10%, Dispersion component ……………………………… 0.1% - 5%, The balance is mineral admixture; The pore-dense component is dense filler; the pore-forming film component is redispersible powder; the particle coating component is an oil-soluble organic matter with a vaporization temperature of 60 - 300 °C; the particle coating component uniformly and densely coats the surfaces of the pore-dense component and the pore-forming film component.

2. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, after being vaporized, the particle coating component uniformly coats the surfaces of the pore-dense component and the pore-forming film component.

3. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, both the pore-dense component and the pore-forming film component coated with the particle coating component are in a spherical or quasi-spherical structure.

4. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, in the preparation raw materials of the coated slow-release medium transmission inhibitor, the mass percentage of the particle coating component is 0.5% - 3.5%.

5. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, the dense filler is one or a combination of several of silica fume, densified silica fume, nano-silica, nano-calcium carbonate, nano-titanium dioxide.

6. The coated slow-release medium transmission inhibitor according to claim 5, characterized in that, The specific surface area of the silica fume and the densified silica fume is 20,000 to 25,000 m 2 / kg.

7. The coated slow-release medium transmission inhibitor according to claim 5, characterized in that, the particle sizes of the nano-silica, nano-calcium carbonate, and nano-titanium dioxide are between 10 - 1000 nm.

8. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, the redispersible powder is one of VAE powder and styrene-based powder.

9. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, the oil-soluble organic matter is one or a combination of several of paraffin, stearic acid, and organosiloxane.

10. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, the dispersion component is a powder-type water reducer.

11. The coated slow-release medium transmission inhibitor according to claim 1, characterized in that, the mineral admixture is one or a combination of several of fly ash, slag powder, and stone powder.

12. The preparation method of the coated slow-release medium transmission inhibitor according to any one of claims 1 - 11, characterized in that, specifically includes the following steps: (1) Add the pore-dense component and the pore-forming film component into the mixer. After stirring evenly, heat up the temperature in the mixer to 60 - 300 °C, and slowly add the vaporized particle coating component. Control the temperature in the mixer so that the added particle coating component remains in a vaporized state, and through the mixing process of the materials, make the lipophilic organic matter form a uniform adsorption on the surface of the solid powder particles. Then slowly lower the temperature so that the vaporized film adsorbed on the particle surface gradually solidifies and forms a coating film; (2) Lower the temperature in the mixer to below 60 °C, add the dispersion component and the mineral admixture into the mixer, continue to mix evenly and then discharge the material, thus obtaining the coated slow-release medium transmission inhibitor.

13. Application of the coated slow-release medium transmission inhibitor according to any one of claims 1 - 11, characterized in that, the coated slow-release medium transmission inhibitor is incorporated and used during the concrete mixing process, and the incorporation amount is 5% - 10% of the dosage of the cementitious material.

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