Seawater-resistant concrete repair material and preparation method thereof

Abstract

The present application provides a seawater-resistant concrete repair material, which consists of two ingredients: a repairable high-bonding concrete ingredient M1 and a salt-resistant and antibacterial dense concrete ingredient M2. The composition of the repairing high-bonding concrete mix M1 is 55-65wt.% modified magnesium phosphate cement, 1.5-2.5wt.% ternary copolymer polyacrylamide, 25-35wt.% quartz sand with a fineness modulus of 2.5-2.7, and 5-10wt.% ultrafine steel fiber with a cross-sectional area of ​​0.01mm2 or less. The composition of the salt-resistant and antibacterial dense concrete mix M2 is 55-60wt.% modified magnesium phosphate cement, 0.4-0.8wt.% ternary copolymer polyacrylamide, 10-20wt.% coarse aggregate, 10-15wt.% fine aggregate, 5-10wt.% ordinary steel fiber, 0.1-0.5wt.% water reducer, and 0.01-0.5wt.% cuprous oxide. By combining the two concrete mixes, a stable and excellent repair effect can be achieved.

Description

Technical Field

[0001] The present application belongs to the field of concrete, and specifically relates to a seawater-resistant concrete repair material used in marine environments and a preparation method thereof. Background Art

[0002] As we all know, the marine environment is quite different from the terrestrial environment, primarily due to the presence of large amounts of salt and marine microorganisms in seawater. While the main factors contributing to concrete failure on land are oxygen erosion and external impact, in the marine environment, the primary factors contributing to concrete failure are chloride ion attack, marine microbial attack, seawater pressure, and periodic tidal impact.

[0003] Therefore, when designing concrete for land use and marine use, researchers approach the design from completely different perspectives to ensure that the concrete is suitable for the respective environments. Similarly, when researching repair materials for land-based and marine-based concrete, different failure causes and usage environments must be considered.

[0004] Currently, there is no comprehensive research on marine concrete repair materials, and repair materials used for terrestrial concrete are typically used. However, when used to repair marine concrete, these terrestrial concrete repair materials suffer from poor repair effectiveness, unstable performance, and short lifespan. Therefore, this application aims to provide a seawater-resistant concrete repair material and a method for its preparation. Summary of the Invention

[0005] In order to fill the relative gap in concrete repair materials specifically for use in marine engineering environments, the present application provides a seawater-resistant concrete repair material and a preparation method thereof that are particularly suitable for use in marine engineering environments. The material can effectively repair partially failed concrete in marine engineering environments with good repair effects, stable performance and long service life.

[0006] A seawater-resistant concrete repair material, comprising two ingredients: a repairable high-bonding concrete ingredient M1 and a salt-resistant and antibacterial dense concrete ingredient M2;

[0007] Among them, the composition of the repairable high-bonding concrete mix M1 is:

[0008]

[0009] Among them, the composition of salt-resistant and antibacterial dense concrete mix M2 is:

[0010]

[0011] Among them, the repairing high-bonding concrete ingredient M1 is used to directly repair the failed parts of the concrete, and the salt-resistant and antibacterial dense concrete ingredient M2 is used to enhance the strength and life of the repaired concrete.

[0012] Furthermore, the modified magnesium phosphate cement is composed of: magnesium oxide: potassium dihydrogen phosphate: aluminum silicate: EDTA-2Na in a mass ratio of (20-30): (20-25): (4-8): (1-5).

[0013] Furthermore, the ternary copolymer polyacrylamide is a ternary copolymer polyacrylamide of acrylamide, acrylic acid, and allyl-A-D-galactopyranoside.

[0014] Furthermore, the acrylamide, acrylic acid, and allyl-A-D-galactopyranoside ternary copolymerized polyacrylamide preferably has a structure as shown in (I),

[0015]

[0016] Wherein, in formula (I), x:y:z=(50-70):(15-25):(15-25).

[0017] Furthermore, in the repairable high-bonding concrete mix M1, the content of the ternary copolymer polyacrylamide is preferably 2-2.5 wt.%.

[0018] Furthermore, the ordinary steel fiber refers to a steel fiber with a cross-sectional area between 0.1 mm 2 -4mm 2 of steel fiber.

[0019] In the repairable high-bonding concrete mix M1, a relatively high content of ternary copolymer polyacrylamide is added, considering its application in seawater. This ensures low turbidity while increasing the concrete's viscosity and reducing its expansion, making repair work in seawater relatively easy. This means that a relatively small amount of concrete can be used to quickly repair specific failure sites. If the ternary copolymer polyacrylamide content is less than 1.5 wt.%, the expansion is too high, making it unsuitable for rapid repair of concrete in marine environments.

[0020] In addition, during the early research process, the inventors found that ternary copolymer polyacrylamide has good water absorption. The more it is incorporated into concrete, the stronger its water absorption is. When the amount incorporated is too much, more water is not discharged during molding. This water evaporates during the hardening process of the mortar, causing certain micropores, which manifests as an increase in the content of harmful pores and multiple harmful pores in the microscopic morphology, and then shows a decrease in compressive strength in the macroscopic. However, in the concrete repair material used in the marine environment of this application, the repairing high-bonding concrete ingredient M1 is used to directly repair the failed part of the concrete, and its outer surface is also surface repaired with the salt-resistant and antibacterial dense concrete ingredient M2, and no coarse aggregate is used. Therefore, it is almost impossible for a large number of harmful pores and multiple harmful pores to form in the repair layer. Therefore, 1.5-2.5wt.% ternary copolymer polyacrylamide is more suitable, and is no longer limited to the upper limit of 1.5wt.% in traditional concrete. More preferably, in the repairable high-bonding concrete mix M1, the content of the ternary copolymer polyacrylamide is preferably 2-2.5 wt.%.

[0021] At the same time, the function of the repairable high-bonding concrete mix M1 is to quickly repair the parts that need to be repaired and serve as an intermediate layer to receive the external salt-resistant and antibacterial concrete layer. No coarse aggregate is added to its composition. However, this will reduce the strength of the intermediate layer. To this end, the present application adds a cross-sectional area of ​​​​less than or equal to 0.01mm in the repairable high-bonding concrete mix M1. 2 Ultrafine steel fibers. General steel fibers have excellent tensile strength and can be used to improve the compressive strength, tensile strength, flexural strength, impact strength, toughness, impact toughness and other properties of concrete. The cross-sectional area S1 used in this application is less than or equal to 0.01mm 2 The steel fibers not only improve the strength of concrete, but also effectively increase the density of the middle layer of concrete, thereby increasing the stability and service life of the repaired concrete. When the cross-sectional area of ​​the steel fibers is too large, the density of the concrete will decrease as the cross-sectional area increases.

[0022] The salt-resistant and antibacterial dense concrete mix M2 is used to repair the entire concrete surface and improve the strength and life of the entire concrete surface. Therefore, compared with the repairing high-bonding concrete mix M1, the expansion of the concrete made from the salt-resistant and antibacterial dense concrete mix M2 needs to be appropriately increased, and it is also necessary to maintain a relatively high viscosity and low turbidity. Therefore, it is necessary to control the content of ternary copolymer polyacrylamide within the range of 0.4-0.8wt.%. If the content of ternary copolymer polyacrylamide is too high, especially above 1.2wt.%, the expansion of the concrete will decrease significantly, which will affect the strength of the concrete.

[0023] Furthermore, in the salt-resistant and antibacterial dense concrete mix M2, it is necessary to use both fine aggregate and coarse aggregate to maintain the basic strength of the concrete. In addition, it is necessary to further add ordinary steel fibers, and utilize the excellent tensile / compressive strength of ordinary steel fibers to improve the compressive strength, tensile strength, flexural strength, impact strength, toughness, impact toughness and other properties of concrete. At the same time, considering the cost factor, ordinary steel fibers can be used. In addition, in order to enhance the antibacterial properties of concrete, especially for microorganisms in the marine environment, an appropriate amount of cuprous oxide is added. Thus, by improving the antibacterial properties, the microbial erosion of concrete caused by the attachment of marine microorganisms to the concrete surface can be reduced, thereby increasing the life of the concrete.

[0024] The modified magnesium phosphate cement used in this application is made from magnesium oxide, potassium dihydrogen phosphate, silicon oxide, aluminum oxide, and EDTA-2Na in appropriate proportions. EDTA-2Na is suitable for use in marine environments and can appropriately extend the setting time of magnesium phosphate cement in marine construction environments. Aluminum silicate can react with potassium dihydrogen phosphate and magnesium oxide to form various stable products, such as magnesium aluminum phosphate and magnesium aluminum silicate, improving the concrete's salt resistance, water resistance, and strength. DETAILED DESCRIPTION

[0025] The specific solutions of this application will be described in detail below.

[0026] Preparation Example 1

[0027] Acrylamide, acrylic acid, and allyl-A-D-galactopyranoside ternary copolymerized polyacrylamide are prepared in the following steps:

[0028] 1) Weigh 42.65 g (about 0.6 mol) of acrylamide, 14.41 g (about 0.2 mol) of acrylic acid, and 44.04 g (about 0.2 mol) of allyl-A-D-galactopyranoside, and dissolve them in 404.4 g of deionized water to obtain an aqueous solution with a total mass concentration of 20 wt.%;

[0029] 2) adding 0.17 g of urea (approximately 0.4 wt.% of acrylamide), 0.085 g of EDTA-2Na (approximately 0.2 wt.% of acrylamide), and 0.17 g of sodium formate (approximately 0.4 wt.% of acrylamide) to the aqueous solution in sequence, and stirring uniformly at room temperature;

[0030] 3) Adjust the pH to 8 with NaOH solution, and then introduce nitrogen to deoxygenate for 28 minutes;

[0031] 4) Add 0.26 g of azobisisobutylimidazoline hydrochloride (approximately 0.6 wt.% of acrylamide) and seal the container and heat at 20° C. for 4 hours;

[0032] 5) Add 0.26 g of ammonium persulfate (approximately 0.6 wt.% of acrylamide) and seal the container and heat at 35° C. for 5 hours;

[0033] 6) The obtained colloidal product is taken out, dried and crushed to obtain powdered polyacrylamide, which is recorded as M1.

[0034] The product M1 of Example 1 was subjected to infrared spectroscopy (IR) and quantitative 13C spectrum determination.

[0035] In the IR spectrum, the stretching vibration peak of the carbonyl group (C=O) in the amide group appears at 1656 cm -1 The stretching vibration peak of the primary amide (-NH2) in the amide group appears at 3348 cm -1 The stretching vibration peak of secondary amide (-NH) is at 3178cm -1 The stretching vibration peak of -CN is at 1119cm -1 1405cm -1 and 1549cm -1 The absorption peaks at 2918 cm-1 are the symmetric and antisymmetric stretching vibration peaks of the carboxyl group (-COO-). The characteristic absorption peak of the methylene group (-CH2) in the skeleton is at 2918 cm-1. -1 1316cm -1 The peak at is caused by the stretching vibration of the methine (-CH).

[0036] Quantitative 13C spectrometry revealed characteristic peaks for the pyranose rings C1-C6 at 61.02-102.77 ppm. The integrated area of ​​the characteristic peaks revealed an x:y:z ratio of approximately 3:1:1. Viscometry revealed a viscosity-average molecular weight (Mv) of 14.83 million, with a monomer conversion rate exceeding 99.9%. This confirms that the polyacrylamide prepared in this example has the structure shown in Formula (I).

[0037] (I)

[0038] And the x:y:z is 3:1:1.

[0039] Preparation Example 2

[0040] The modified magnesium phosphate cement is prepared according to the mass ratio of magnesium oxide: potassium dihydrogen phosphate: aluminum silicate: EDTA-2Na of 30 kg: 25 kg: 6 kg: 3 kg.

[0041] Example 1

[0042] A seawater-resistant concrete repair material, comprising two ingredients: a repairable high-bonding concrete ingredient M1 and a salt-resistant and antibacterial dense concrete ingredient M2;

[0043] Among them, the composition of the repairable high-bonding concrete mix M1 is:

[0044]

[0045] Among them, the composition of salt-resistant and antibacterial dense concrete mix M2 is:

[0046]

[0047] Example 2

[0048] A seawater-resistant concrete repair material, comprising two ingredients: a repairable high-bonding concrete ingredient M1 and a salt-resistant and antibacterial dense concrete ingredient M2;

[0049] Among them, the composition of the repairable high-bonding concrete mix M1 is:

[0050]

[0051] Among them, the composition of salt-resistant and antibacterial dense concrete mix M2 is:

[0052]

[0053] Example 3

[0054] A seawater-resistant concrete repair material, comprising two ingredients: a repairable high-bonding concrete ingredient M1 and a salt-resistant and antibacterial dense concrete ingredient M2;

[0055] Among them, the composition of the repairable high-bonding concrete mix M1 is:

[0056]

[0057]

[0058] Among them, the composition of salt-resistant and antibacterial dense concrete mix M2 is:

[0059]

[0060] Comparative Example

[0061] In order to verify and compare the excellent performance and effect of the seawater-resistant concrete repair material of the present application, the following comparative examples are set for comparison.

[0062] Comparative Example 1

[0063] The salt-resistant and antibacterial dense concrete mix M2 in Example 1 is directly used as a repair material for repairing concrete structures in marine environments, and the repairable high-bonding concrete mix M1 is omitted.

[0064] Comparative Example 2

[0065] The repairing high-bonding concrete mix M1 in Example 1 is directly used as the repair material for repairing the concrete structure in the marine environment, and the salt-resistant and antibacterial dense concrete mix M2 is omitted.

[0066] Comparative Example 3

[0067] The content of ternary copolymerized polyacrylamide in M1 of Example 1 was reduced to 0.6 wt.%, and the content of modified magnesium phosphate cement was increased to 56.4 wt.%.

[0068] Comparative Example 4

[0069] The content of terpolymer polyacrylamide in M2 of Example 1 was increased to 2 wt.%, and the content of coarse aggregate was reduced to 22.4 wt.%.

[0070] Comparative Example 5

[0071] The ultrafine steel fibers in the restorative high-bonding concrete mix M1 of Example 1 were replaced with ordinary steel fibers of corresponding content.

[0072] Comparative Example 6

[0073] The cuprous oxide in the salt-resistant and antibacterial dense concrete mix M2 of Example 1 was omitted.

[0074] The concrete repair materials of Examples 1-3 and Comparative Examples 1-6 were respectively used to repair concrete in a simulated marine environment, and then performance tests were performed.

[0075] The repair method is as follows: first, remove the defective parts of the failed parts of the concrete in the simulated marine environment, then apply the concrete slurry made of the repairable high-bonding concrete ingredient M1 to the cleaned area to be repaired, and then apply the concrete slurry made of the salt-resistant and antibacterial dense concrete ingredient M2 to the surface of the concrete slurry made of the repairable high-bonding concrete ingredient M1.

[0076] The tested properties include 28-day compressive strength, bonding strength between the repair structure and the repair matrix, resistance to chloride ion penetration, and antibacterial properties.

[0077] Chloride ion penetration resistance was assessed using the DC coulometric method, following the test method outlined in the "Standard for Electrical Evaluation of Chloride Ion Permeability of Concrete." The specimens were vacuum-saturated with water, and the current flowing through them was then measured at 60V DC voltage every 30 minutes for 6 hours. Permeability was graded from best to worst as "impermeable," "very low," "low," "medium," and "high." See Table 1 for detailed test results.

[0078] Table 1 Performance test results

[0079]

[0080] From the performance test results in Table 1, it can be found that the seawater-resistant concrete repair material of the present application is used to repair concrete structures in marine environments according to the method of "first removing the defective parts of the failed parts of the concrete in the simulated marine environment, and then making the repairing high-bonding concrete ingredient M1 into a concrete slurry and applying it to the area to be repaired after the removal, and then making the salt-resistant and antibacterial dense concrete ingredient M2 into a concrete slurry and applying it on the surface of the concrete slurry made of the repairing high-bonding concrete ingredient M1". Excellent compressive strength, bonding strength, antibacterial properties, and extremely low resistance to chloride ion penetration are obtained.

Claims

1. A seawater-resistant concrete repair material, comprising two ingredients: a repairable high-bonding concrete ingredient M1 and a salt-resistant and antibacterial dense concrete ingredient M2; in, The composition of the repairable high-bonding concrete mix M1 is: Modified magnesium phosphate cement 55-65wt.% Ternary copolymer polyacrylamide 1.5-2.5wt.% 25-35wt.% quartz sand with a fineness modulus of 2.5-2.7 Cross-sectional area less than or equal to 0.01mm 2 Ultrafine steel fiber 5-10wt.% Among them, the composition of salt-resistant and antibacterial dense concrete mix M2 is: Modified magnesium phosphate cement 55-60wt.% Ternary copolymer polyacrylamide 0.4-0.8wt.% Coarse aggregate 10-20wt.% Fine aggregate 10-15wt.% Ordinary steel fiber 5-10wt.% Water reducing agent 0.1-0.5wt.% Cuprous oxide 0.01-0.5wt.%; Wherein, the sum of the components constituting the salt-resistant and antibacterial dense concrete mix M2 is 100%; The repairable high-bonding concrete mix M1 is used to directly repair failed parts of the concrete, and the salt-resistant and antibacterial dense concrete mix M2 is used to enhance the strength and life of the repaired concrete. The modified magnesium phosphate cement is composed of: magnesium oxide: potassium dihydrogen phosphate: aluminum silicate: EDTA-2Na in a mass ratio of (20-30): (20-25): (4-8): (1-5); The ternary copolymer polyacrylamide is a ternary copolymer polyacrylamide of acrylamide, acrylic acid, and allyl-A-D-galactopyranoside; and has a structure as shown in (I). Wherein, in formula (I), x:y:z=(50-70):(15-25):(15-25).

2. The seawater-resistant concrete repair material according to claim 1, characterized in that: In the repairable high-bonding concrete mix M1, the content of ternary copolymer polyacrylamide is 2-2.5 wt.%.

3. The seawater-resistant concrete repair material according to claim 1, characterized in that: The ordinary steel fiber refers to a steel fiber with a cross-sectional area of ​​0.1 mm 2 -4mm 2 of steel fiber.

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