Cement-based protective material with ion capture and induced passivation functions and application thereof

Abstract

This invention relates to the field of cement building materials, specifically disclosing a cement-based protective material with both ion trapping and induced passivation functions and its application. The cement-based protective material comprises the following components: 95-100 parts by weight of magnesium phosphate cement, 4-6 parts by weight of retarder, and 20-25 parts by weight of composite modifier. The composite modifier comprises modified dry powder, calcium-containing dry powder, mixing water, and a dispersant, and the modified dry powder is obtained by calcining a layered bimetallic hydroxide with an aluminum source. The cement-based protective material of this invention exhibits high Cl- content... ‑ SO4 2‑ In addition to its excellent impermeability in CO2 environments, it can also actively capture corrosive ions, promote the formation and maintenance of a stable passivation film on the steel surface, thereby providing more long-lasting and reliable protection for marine steel structures.

Description

Technical Field

[0001] This invention relates to the field of cement building materials, specifically to a cement-based protective material with both ion trapping and induced passivation functions and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] With the vigorous development of my country's marine economy and new energy industry, a large number of steel structure facilities such as offshore wind power, cross-sea bridges, port terminals, and submarine pipelines have been built. These facilities operate for extended periods in harsh marine environments, facing high concentrations of chloride ions (Cl). - ), sulfate ions (SO4) 2- Corrosion is caused by a combination of factors, including dissolved carbon dioxide (CO2), fluctuations in oxygen concentration, and microorganisms. Among these, Cl... - Corrosion by SO4 is a major cause of pitting corrosion and stress corrosion cracking in steel, and high SO4 content... 2- The environment will exacerbate the chemical erosion and expansion damage of concrete or coating materials, causing the anti-corrosion coating of steel structures to fail rapidly, seriously threatening the safety and service life of engineering structures.

[0004] To address the aforementioned issues, magnesium phosphate cement-based coatings have been increasingly adopted for the protection of marine steel structures due to their high early strength, excellent adhesion, and environmental friendliness. However, traditional magnesium phosphate cement-based coatings lack sufficient long-term corrosion protection under prolonged seawater immersion, especially against various corrosive ions (Cl). - SO4 2- Under the coupling effect of CO2, pore development and Cl2 are likely to occur. - Problems such as penetration and passivation film damage make it difficult to meet the long-term corrosion protection requirements of marine engineering. Summary of the Invention

[0005] This invention provides a cement-based protective material with both ion trapping and induced passivation functions, and its application. This material is suitable for use in high Cl- environments. - SO4 2- In CO2 environments, it not only possesses excellent impermeability but also actively captures corrosive ions, promotes the formation and maintenance of a stable passivation film on the steel surface, thereby providing more long-lasting and reliable protection for marine steel structures. Specifically, the technical solution of this invention is as follows.

[0006] First, this invention provides a cement-based protective material with both ion trapping and induced passivation functions. Its raw materials include the following components: 95-100 parts by weight of magnesium phosphate cement, 4-6 parts by weight of retarder, and 20-25 parts by weight of composite modifier. The composite modifier comprises modified dry powder, calcium-containing dry powder, mixing water, and a dispersant, and the modified dry powder is formed by calcining a layered bimetallic hydroxide with an aluminum source.

[0007] Furthermore, the retarder includes at least one of borax, boric acid, etc.

[0008] Further, the magnesium phosphate cement is composed of magnesium oxide and phosphate in a mass ratio of 2-3:1. Optionally, the phosphate includes at least one of potassium dihydrogen phosphate, aluminum dihydrogen phosphate, etc.

[0009] Furthermore, the mass ratio of the modified dry powder, calcium-containing dry powder, mixing water, and dispersant is 1.5~6:1~2:18~20:0.03~0.05.

[0010] Further, the calcium-containing dry powder includes at least one of carbide slag, quicklime, etc. Optionally, the fineness of the calcium-containing dry powder is 200-300 mesh.

[0011] Furthermore, the dispersant includes at least one of sodium hexametaphosphate, sodium polyacrylate, etc.

[0012] Furthermore, the calcination temperature is 500~600℃, and the calcination time is 4~5 hours.

[0013] Furthermore, the modified dry powder has a fineness of 250-400 mesh.

[0014] Furthermore, the mass ratio of the layered bimetallic hydroxide to the aluminum source is 1~2.3:1.

[0015] Further, the layered bimetallic hydroxide includes at least one of Ca / Al-LDH, Mg / Al-LDH, etc. The aluminum source includes at least one of aluminum hydroxide, bauxite extract, etc., preferably bauxite extract.

[0016] Further, the preparation process of the bauxite extract includes: placing bauxite powder in nitric acid with a mass fraction of 10-15% and heating to 50-60°C for leaching for 4-5 hours. After extraction, allow it to stand, take the supernatant, and add alkali solution dropwise until no more precipitate appears. Then, separate the precipitate, wash, and dry to obtain the bauxite extract. Optionally, the alkali solution includes at least one of sodium hydroxide, potassium hydroxide, and ammonia.

[0017] Secondly, this invention provides the application of the cement-based protective material with both ion trapping and induced passivation functions in fields such as building engineering, marine engineering, and water conservancy and hydropower engineering.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0019] This invention uses layered bimetallic hydroxide (LDH) and modified dry powder formed by calcination of an aluminum source as components of a composite modifier. On one hand, the LDH decomposes to form amorphous magnesium aluminum oxide with a high specific surface area and rich in defects, which further forms a composite structure with γ-Al2O3 decomposed from the aluminum source, significantly improving its activity and stability in subsequent applications. On the other hand, the decomposition of the aluminum source to form γ-Al2O3 is exothermic and leads to local sintering, while the decomposition products of the LDH act as physical barrier agents to effectively isolate the agglomeration of γ-Al2O3 particles, thereby maintaining a smaller grain size and higher specific surface area of ​​γ-Al2O3, which is more conducive to ion adsorption. On the other hand, the surface of the LDH decomposition products has abundant alkaline sites and structural defects, while the surface of γ-Al2O3 is mainly acidic. During the calcination process, the two form a unique acid-base bifunctional surface. Furthermore, γ-Al2O3 provides an additional aluminum source to penetrate into the layers of LDH decomposition products, increasing the cation charge density in the layers. This results in a layer structure with higher crystallinity and a more complete structure, effectively enhancing the adsorption capacity of the modified dry powder of the present invention for anions. Consequently, the composite modifier of the present invention has a better ability to improve the corrosion resistance of protective materials.

[0020] When the composite modifier of the present invention is incorporated into magnesium phosphate cement, on the one hand, the highly active γ-Al2O3 and the magnesium ions provided by magnesium oxide in the magnesium phosphate cement participate in the reconstruction of the LDH product layer to form RBD-CLDH. In this structure, Al 3+ Partially replaces Mg 2+ / Ca 2+ This leads to an increase in the positive charge density of the layers, requiring more interlayer anions to balance the charge. Therefore, compared to the uncalcined layered bimetallic oxide, it has a stronger adsorption capacity for anions, effectively improving the adsorption capacity and thus enabling the adsorption of more Cl. - SO4 2- The RBD-CLDH effectively enhances the ability to capture anions in seawater environments, reducing the amount of corrosive media penetrating the protective material layer to the steel surface. Furthermore, the RBD-CLDH preferentially captures and stores anions such as phosphate and hydrogen phosphate in the interlayer during the early hydration stage of magnesium phosphate cement. When the amount of corrosive media in seawater... - SO4 2-After invasion, the phosphate and hydrogen phosphate ions between the attack layers exchange to form stable RBD-LDH-Cl. - With RBD-LDH-SO4 2- The released phosphate and hydrogen phosphate ions diffuse to the steel surface and interact with the Fe on the surface. 2+ The phosphating reaction of Fe(OH)2, FeOOH, etc., generates a stable iron phosphate passivation film, passivating the steel surface. This mechanism actively captures corrosive ions, promoting the formation and maintenance of a stable passivation film on the steel surface. This achieves a triple anti-corrosion mechanism of "chemical passivation + capture + physical barrier," providing longer-lasting and more reliable protection for steel structures. Furthermore, the calcium-containing dry powder in the composite modifier of this invention provides an alkaline environment, facilitating the initial formation of an alkaline passivation film and promoting the generation of the RBD-LDH. Moreover, the active γ-Al2O3 reacts with Ca(OH)2 in the calcium-containing dry powder to generate hydrated calcium aluminate, which can further react with invading Cl-. - and SO4 2- The reaction produces Friedel's salt or Kuzel's salt to achieve the reaction with Cl. - and SO4 2- The calcium ions provided by the calcium-containing dry powder can react with the phosphate ions released during the hydration of magnesium phosphate cement to form slightly soluble tricalcium phosphate (Ca3(PO4)2). These fine precipitates precisely fill the micropores and gaps in the matrix of the protective material, improving the overall density, reducing the material's permeability, and further enhancing the protective performance of the cement-based protective material of this invention. Finally, the highly active γ-Al2O3 and RBD-CLDH can also provide hydration sites for magnesium phosphate cement, facilitating the anchoring of the formed ferric phosphate / ferrous phosphate passivation film onto the steel surface, increasing the bonding strength between the protective material and the steel, and helping to prevent protective failure caused by the detachment of the protective layer. Attached Figure Description

[0021] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein:

[0022] Figure 1 The image shows a sample of the composite modifier prepared in Example 1 below.

[0023] Figure 2 The following is a test diagram of the bond strength between the cement-based protective material and steel in Example 1.

[0024] Figure 3 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 1.

[0025] Figure 4 The image shows a sample of the composite modifier prepared in Example 2 below.

[0026] Figure 5 The following is a test diagram of the bond strength between the cement-based protective material and steel in Example 2.

[0027] Figure 6 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 2.

[0028] Figure 7 The image shows a sample of the composite modifier prepared in Example 3 below.

[0029] Figure 8 The following is a test diagram of the bond strength between the cement-based protective material and steel in Example 3.

[0030] Figure 9 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 3.

[0031] Figure 10 The image shows a sample of the composite modifier prepared in Example 4 below.

[0032] Figure 11 The following is a test diagram of the bond strength between the cement-based protective material and the steel in Example 4.

[0033] Figure 12 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 4.

[0034] Figure 13 The image shows a sample of the composite modifier prepared in Example 5 below.

[0035] Figure 14 The following is a test diagram of the bond strength between the cement-based protective material and steel in Example 5.

[0036] Figure 15 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 5.

[0037] Figure 16 The image shows a sample of the composite modifier prepared in Example 6 below.

[0038] Figure 17 The following is a test diagram of the bond strength between the cement-based protective material and steel in Example 6.

[0039] Figure 18 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 6.

[0040] Figure 19The image shows a sample of the composite modifier prepared in Example 7 below.

[0041] Figure 20 The following is a test diagram of the bond strength between the cement-based protective material and steel in Example 7.

[0042] Figure 21 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 7.

[0043] Figure 22 The image shows a sample of the composite modifier prepared in Example 8 below.

[0044] Figure 23 The following is a test diagram of the bond strength between the cement-based protective material and the steel in Example 8.

[0045] Figure 24 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 8.

[0046] Figure 25 The image shows a sample of the composite modifier prepared in Example 9 below.

[0047] Figure 26 The following is a test diagram of the bond strength between the cement-based protective material and steel in Example 9.

[0048] Figure 27 The following is a test diagram of the bond strength between the cement-based protective material and concrete in Example 9. Detailed Implementation

[0049] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention.

[0051] Example 1

[0052] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0053] (1) Layered bimetallic hydroxide (Ca / Al-LDH) and aluminum hydroxide were mixed at a mass ratio of 2:1 and then mixed at a speed of 200 r / min for 30 min to obtain a mixed powder. The mixed powder was then placed in a muffle furnace and heated to 600℃ for 4 hours at a heating rate of 10℃ / min. After completion, it was cooled to room temperature, and the obtained calcined product was ground and passed through a 300-mesh sieve to obtain a modified dry powder for later use.

[0054] (2) Weigh each component according to the mass ratio of the modified dry powder, calcium-containing dry powder (carbide slag, 300 mesh), mixing water, and dispersant (sodium hexametaphosphate) described in this embodiment: 3.5:1.5:18:0.04. Then, first add the calcium-containing dry powder to the water, and then add the dispersant and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the obtained suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium hexametaphosphate). Figure 1 (As shown), for later use.

[0055] (3) Take the following components in the following proportions: 100 parts by weight of magnesium phosphate cement, 5 parts by weight of retarder (borax), and 23 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 2.5:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0056] Performance Testing: (S1) According to the "Adhesion Test of Paint and Varnish by Pull-Off Method" (GB / T-5210-2006), the bond strength A1 between the cement-based protective material prepared in this embodiment and steel and concrete was tested respectively (results were 1.15MPa and 4.06MPa, respectively). Then, the bond strength A2 after 84 days of simulated seawater immersion was tested, and the strength retention rate was calculated and recorded as A1 retention rate and A2 retention rate, respectively. The higher the value, the better the anti-detachment effect of the cement-based protective material under seawater erosion. The bond strength tests between the cement-based protective material and steel and concrete are as follows: Figure 2 , Figure 3 As shown. (S2) Apply the cement-based protective material to the Q235 steel sheet, seal the edges with epoxy, leaving a 1cm margin. 2 Using the protective layer as the working area, the corrosion resistance of the protective layer was tested using a CHI660E electrochemical workstation after 28 and 84 days of simulated seawater immersion. Simultaneously, the corrosion current density i was fitted using the Tafel extrapolation method. ccor The polarization resistance Rp. The test results for each performance indicator are shown in Table 1 below.

[0057] Table 1

[0058] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 90.29% 95.57% <![CDATA[1.8783μA / cm 2 ]]> <![CDATA[22774Ω·cm 2 ]]> <![CDATA[0.9377μA / cm 2 ]]> <![CDATA[45754Ω·cm 2 ]]>

[0059] Example 2

[0060] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0061] (1) Layered bimetallic hydroxide (Mg / Al-LDH) and aluminum hydroxide were mixed at a mass ratio of 1:1 and then mixed at a speed of 200 r / min for 30 min to obtain a mixed powder. The mixed powder was then placed in a muffle furnace and heated to 500℃ for 5 hours at a heating rate of 10℃ / min. After completion, it was cooled to room temperature, and the obtained calcined product was ground and passed through a 400-mesh sieve to obtain a modified dry powder for later use.

[0062] (2) Weigh each component according to the mass ratio of the modified dry powder, calcium-containing dry powder (quicklime, 200 mesh), mixing water, and dispersant (sodium hexametaphosphate) described in this embodiment = 1.5:1:19:0.03. Then, first add the calcium-containing dry powder to the water, and then add the dispersant and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the obtained suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium hexametaphosphate). Figure 4 (As shown), for later use.

[0063] (3) Take the following components in the following proportions: 95 parts by weight of magnesium phosphate cement, 4 parts by weight of retarder (borax), and 20 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 3:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0064] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 5 , Figure 6 As shown in the figure, the results are 0.99 MPa and 3.86 MPa, respectively. The test results of each performance index are shown in Table 2 below.

[0065] Table 2

[0066] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 84.84% 89.79% <![CDATA[2.3504μA / cm 2 ]]> <![CDATA[19938Ω·cm 2 ]]> <![CDATA[1.3071μA / cm 2 ]]> <![CDATA[40940Ω·cm 2 ]]>

[0067] Example 3

[0068] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0069] (1) Layered bimetallic hydroxide (Mg / Al-LDH) and aluminum hydroxide were mixed at a mass ratio of 2.3:1 and then mixed at a speed of 200 r / min for 35 min to obtain a mixed powder. The mixed powder was then placed in a muffle furnace and heated to 500℃ for 4.5 hours at a heating rate of 10℃ / min. After completion, it was cooled to room temperature, and the obtained calcined product was ground and passed through a 250 mesh sieve to obtain a modified dry powder for later use.

[0070] (2) Weigh each component according to the mass ratio of the modified dry powder, calcium-containing dry powder (quicklime, 300 mesh), mixing water, and dispersant (sodium polyacrylate) described in this embodiment: 6:2:20:0.05. First, add the calcium-containing dry powder to water, then add the dispersant and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the resulting suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium polyacrylate). Figure 7 (As shown), for later use.

[0071] (3) Take the following components in the following proportions: 98 parts by weight of magnesium phosphate cement, 6 parts by weight of retarder (boric acid), and 25 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 2:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0072] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 8 , Figure 9 As shown, the results were 1.34 MPa and 4.41 MPa, respectively. The test results for each performance index are shown in Table 3 below.

[0073] Table 3

[0074] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 87.36% 93.65% <![CDATA[2.1512μA / cm 2 ]]> <![CDATA[24758Ω·cm 2 ]]> <![CDATA[0.7904μA / cm 2 ]]> <![CDATA[55662Ω·cm 2 ]]>

[0075] Example 4

[0076] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0077] (1) Weigh each component according to the mass ratio of calcium-containing dry powder (carbide slag, fineness 300 mesh), mixing water, and dispersant (sodium hexametaphosphate) = 1.5:18:0.04. Then, first add the calcium-containing dry powder to the water, and then add the dispersant and stir at a speed of 500 r / min for 6 min to obtain the composite modifier (e.g., sodium hexametaphosphate). Figure 10 (As shown), for later use.

[0078] (2) Take the following components in the following proportions: 100 parts by weight of magnesium phosphate cement, 5 parts by weight of retarder (borax), and 23 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 2.5:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0079] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 11 , Figure 12 As shown, the results were 0.74 MPa and 2.85 MPa, respectively. The test results for each performance index are shown in Table 4 below.

[0080] Table 4

[0081] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 74.32% 80.04% <![CDATA[6.5766μA / cm 2 ]]> <![CDATA[6035Ω·cm 2 ]]> <![CDATA[6.848μA / cm 2 ]]> <![CDATA[6120Ω·cm 2 ]]>

[0082] Example 5

[0083] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0084] (1) The layered bimetallic hydroxide (Ca / Al-LDH) was mixed at 200 r / min for 30 min and then placed in a muffle furnace. It was then heated to 600 °C for 4 hours at a heating rate of 10 °C / min. After the calcination was completed, it was cooled to room temperature, and the calcined product was ground and passed through a 300-mesh sieve to obtain modified dry powder for later use.

[0085] (2) Weigh each component according to the mass ratio of the modified dry powder, calcium-containing dry powder (carbide slag, 300 mesh), mixing water, and dispersant (sodium hexametaphosphate) described in this embodiment: 3.5:1.5:18:0.04. Then, first add the calcium-containing dry powder to the water, and then add the dispersant and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the obtained suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium hexametaphosphate). Figure 13 (As shown), for later use.

[0086] (3) Take the following components in the following proportions: 100 parts by weight of magnesium phosphate cement, 5 parts by weight of retarder (borax), and 23 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 2.5:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0087] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 14 , Figure 15 As shown, the results were 0.87 MPa and 3.12 MPa, respectively. The test results for each performance index are shown in Table 5 below.

[0088] Table 5

[0089] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 76.13% 85.44% <![CDATA[2.7335μA / cm 2 ]]> <![CDATA[15392Ω·cm 2 ]]> <![CDATA[4.5809μA / cm 2 ]]> <![CDATA[9383Ω·cm 2 ]]>

[0090] Example 6

[0091] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0092] (1) Weigh each component according to the mass ratio of the modified dry powder to mixing water and dispersant (sodium hexametaphosphate) as described in Example 2 above: 1.5:19:0.03. Then, first add the dispersant to the water and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the obtained suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium hexametaphosphate). Figure 16 (As shown), for later use.

[0093] (2) Take the following components in the following proportions: 95 parts by weight of magnesium phosphate cement, 4 parts by weight of retarder (borax), and 20 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 3:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0094] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 17 , Figure 18 As shown, the results were 0.76 MPa and 3.05 MPa, respectively. The test results for each performance index are shown in Table 6 below.

[0095] Table 6

[0096] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 75.62% 86.17% <![CDATA[3.5781μA / cm 2 ]]> <![CDATA[12077Ω·cm 2 ]]> <![CDATA[3.9154μA / cm 2 ]]> <![CDATA[10842Ω·cm 2 ]]>

[0097] Example 7

[0098] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0099] (1) After mixing aluminum hydroxide powder at a speed of 200 r / min for 35 min, the mixture was placed in a muffle furnace and then heated to 500 °C for 4.5 hours at a heating rate of 10 °C / min. After the mixture was cooled to room temperature, the calcined product was ground and passed through a 250 mesh sieve to obtain modified dry powder for later use.

[0100] (2) Weigh each component according to the mass ratio of the modified dry powder, calcium-containing dry powder (quicklime, 300 mesh), mixing water, and dispersant (sodium polyacrylate) described in this embodiment: 6:2:20:0.05. First, add the calcium-containing dry powder to water, then add the dispersant and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the resulting suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium polyacrylate). Figure 19 (As shown), for later use.

[0101] (3) Take the following components in the following proportions: 98 parts by weight of magnesium phosphate cement, 6 parts by weight of retarder (boric acid), and 25 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 2:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0102] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 20 , Figure 21 As shown, the results were 0.61 MPa and 2.79 MPa, respectively. The test results for each performance index are shown in Table 7 below.

[0103] Table 7

[0104] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 59.01% 72.75% <![CDATA[6.7304μA / cm 2 ]]> 6443Ω·cm² <![CDATA[5.2884μA / cm 2 ]]> <![CDATA[8132Ω·cm 2 ]]>

[0105] Example 8

[0106] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0107] (1) Layered bimetallic hydroxide (Mg / Al-LDH) and aluminum hydroxide were mixed at a mass ratio of 1:1 and then mixed at a speed of 200 r / min for 30 min. After the mixture was completed, the resulting powder was ground and then passed through a 400-mesh sieve to obtain modified dry powder for later use.

[0108] (2) Weigh each component according to the mass ratio of the modified dry powder, calcium-containing dry powder (quicklime, 200 mesh), mixing water, and dispersant (sodium hexametaphosphate) described in this embodiment = 1.5:1:19:0.03. Then, first add the calcium-containing dry powder to the water, and then add the dispersant and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the obtained suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium hexametaphosphate). Figure 22 (As shown), for later use.

[0109] (3) Take the following components in the following proportions: 95 parts by weight of magnesium phosphate cement, 4 parts by weight of retarder (borax), and 20 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 3:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0110] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 23 , Figure 24 As shown, the results were 0.68 MPa and 2.94 MPa, respectively. The test results for each performance index are shown in Table 8 below.

[0111] Table 8

[0112] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 67.64% 75.87% <![CDATA[4.5355μA / cm 2 ]]> <![CDATA[9213Ω·cm 2 ]]> <![CDATA[3.8307μA / cm 2 ]]> <![CDATA[10988Ω·cm 2 ]]>

[0113] Example 9

[0114] The preparation of a cement-based protective material with both ion trapping and induced passivation functions includes the following steps:

[0115] (1) Place 200-mesh bauxite powder in 15% nitric acid and heat to 60°C for 4 hours. After extraction, let stand for 30 minutes, take the supernatant and add sodium hydroxide solution dropwise until no more precipitate appears. Filter out the precipitate and wash it three times with water. Then dry at 80°C to remove moisture to obtain bauxite extract.

[0116] (2) The layered bimetallic hydroxide (Mg / Al-LDH) and the bauxite extract were mixed at a mass ratio of 2.3:1 and then mixed at a speed of 200 r / min for 35 min to obtain a mixed powder. The mixed powder was then placed in a muffle furnace and heated to 500°C at a heating rate of 10°C / min for 4.5 hours. After completion, it was cooled to room temperature, and the obtained calcined product was ground and passed through a 250-mesh sieve to obtain a modified dry powder for later use.

[0117] (3) Weigh each component according to the mass ratio of the modified dry powder, calcium-containing dry powder (quicklime, 300 mesh), mixing water, and dispersant (sodium polyacrylate) described in this embodiment: 6:2:20:0.05. Then, first add the calcium-containing dry powder to the water, and then add the dispersant and stir at 500 r / min for 6 min. After completion, add the modified dry powder to the obtained suspension and stir at 200 r / min for 10 min to obtain the composite modifier (e.g., sodium polyacrylate). Figure 25 (As shown), for later use.

[0118] (4) Take the following components in the following proportions: 98 parts by weight of magnesium phosphate cement, 6 parts by weight of retarder (boric acid), and 25 parts by weight of the composite modifier described in this embodiment. Wherein: the magnesium phosphate cement is composed of magnesium oxide powder and potassium dihydrogen phosphate powder in a mass ratio of 2:1. Mix the magnesium phosphate cement and the retarder and stir for 2 minutes, then add the composite modifier and continue stirring for 3 minutes to obtain the cement-based protective material.

[0119] Performance testing: The various performance indicators of the cement-based protective material prepared in this embodiment were tested using the same method as in Example 1 above. The bond strength A1 between the cement-based protective material and steel and concrete was tested as follows: Figure 26 , Figure 27 As shown, the results were 1.56 MPa and 4.91 MPa, respectively. The test results for each performance index are shown in Table 9 below.

[0120] Table 9

[0121] A1 retention rate A2 retention rate <![CDATA[28 days i ccor > 28-day RP <![CDATA[84 days i ccor > 84 days Rp 92.41% 96.83% <![CDATA[0.9705μA / cm 2 ]]> <![CDATA[31981Ω·cm 2 ]]> <![CDATA[0.6012μA / cm 2 ]]> <![CDATA[59447Ω·cm 2 ]]>

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cement-based protective material with both ion capturing and induced passivation functions, characterized in that, It comprises the following components: 95-100 parts by weight of magnesium phosphate cement, 4-6 parts by weight of retarder, and 20-25 parts by weight of composite modifier; wherein: the composite modifier comprises modified dry powder, calcium-containing dry powder, mixing water and dispersant, and the modified dry powder is calcined from layered bimetallic hydroxide and aluminum source; The mass ratio of the modified dry powder, calcium-containing dry powder, mixing water, and dispersant is 1.5~6:1~2:18~20:0.03~0.05; The calcium-containing dry powder includes at least one of carbide slag and quicklime. The mass ratio of the layered bimetallic hydroxide to the aluminum source is 1~2.3:1; The aluminum source includes at least one of aluminum hydroxide and bauxite extract; The calcination temperature is 500~600℃, and the calcination time is 4~5 hours.

2. The cement-based protective material with both ion trapping and induced passivation functions according to claim 1, characterized in that, The magnesium phosphate cement is composed of magnesium oxide and phosphate in a mass ratio of 2 to 3:1; the phosphate includes at least one of potassium dihydrogen phosphate and aluminum dihydrogen phosphate; the retarder includes at least one of borax and boric acid.

3. The cement-based protective material with both ion trapping and induced passivation functions according to claim 1, characterized in that, The fineness of the calcium-containing dry powder is 200-300 mesh.

4. The cement-based protective material with both ion trapping and induced passivation functions according to claim 1, characterized in that, The dispersant includes at least one of sodium hexametaphosphate and sodium polyacrylate.

5. The cement-based protective material with both ion trapping and induced passivation functions according to claim 1, characterized in that, The layered bimetallic hydroxide includes at least one of Ca / Al-LDH and Mg / Al-LDH.

6. The cement-based protective material with both ion trapping and induced passivation functions according to claim 1, characterized in that, The preparation process of the bauxite extract includes: placing bauxite powder in nitric acid with a mass fraction of 10-15% and heating it to 50-60°C for 4-5 hours for extraction; after completion, allowing it to stand, taking the supernatant, and adding alkali solution dropwise until no more precipitate appears; then separating the precipitate, washing and drying it to obtain the bauxite extract.

7. The cement-based protective material with both ion trapping and induced passivation functions according to claim 6, characterized in that, The alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, and ammonia water.

8. The cement-based protective material with both ion trapping and induced passivation functions according to any one of claims 1-7, characterized in that, The modified dry powder has a fineness of 250~400 mesh.

9. The application of the cement-based protective material with ion trapping and induced passivation functions as described in any one of claims 1-8 in the fields of building engineering, marine engineering or water conservancy and hydropower engineering.

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