A concrete anti-corrosion additive and its preparation method and usage method

Abstract

The present invention discloses a concrete anti-corrosion admixture, as well as its preparation and use methods. The anti-corrosion admixture comprises the following components, by weight: 40-50 parts GHL powder, 45-55 parts poly(p-phenylene benzobisoxazole) fiber, 20-30 parts light-burned magnesium oxide, and 5-10 parts nanocellulose. The GHL powder includes polyacrylamide and modified tuff-limestone mineral powder. This admixture improves the concrete's anti-corrosion properties by enhancing its compactness and hydrophobicity, reducing the decomposition of calcium hydroxide, and thereby delaying calcium dissolution.

Description

Technical Field

[0001] The invention belongs to the technical field of building material concrete admixtures, and in particular relates to a concrete anti-corrosion admixture and a preparation method and a use method thereof. Background Art

[0002] Dissolution is one of the major diseases of hydraulic concrete. Concrete structures in water conservancy and transportation facilities, such as dams, cross-sea bridges, tunnels, and underground pipelines, are exposed to ambient water for long periods of time. The ion concentration difference between the concrete pore solution and the ambient water causes the continuous diffusion and loss of calcium ions and other substances into the ambient water. This leads to the dissolution of the CSH gel, a decrease in concrete alkalinity, and a degradation of material properties. Existing data show that when calcium dissolution reaches 25%, the compressive strength of concrete decreases by 36% and the tensile strength by 66%. When calcium dissolution exceeds 33%, the concrete loses its strength.

[0003] At present, the main preventive measures for the dissolution problem of hydraulic concrete are the following: reducing the water-cement ratio to increase the density of concrete, but an excessively low water-cement ratio not only increases the difficulty of construction but is also not conducive to uniform pouring; the surface is coated with hydrophobic materials such as epoxy resin, but chemical coatings may pollute water bodies and have high requirements for construction technology; in addition, processes such as improving drainage facilities and isolating water contact are not used for structures such as dam concrete that are below the water level all year round.

[0004] The above measures have certain limitations in preventing and controlling the corrosion of hydraulic concrete and cannot fundamentally solve the problem of calcium ion dissolution in concrete. Therefore, it is necessary to study an admixture that improves the corrosion resistance of concrete itself to fundamentally solve the problem of calcium dissolution in concrete. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a concrete anti-corrosion admixture, which improves the hydrophobicity and density of the concrete itself by adding GHL powder and nanocellulose, and reduces the occurrence of concrete cracks and the erosion of environmental water by combining with poly(p-phenylene benzobisoxazole) fiber; another purpose of the present invention is to provide a method for preparing the concrete anti-corrosion admixture; another purpose of the present invention is to provide a method for using the concrete anti-corrosion admixture.

[0006] Technical solution: The present invention provides an anti-corrosion admixture for concrete, comprising the following components: by weight, 40 to 50 parts of GHL powder, 45 to 55 parts of poly(p-phenylene benzobisoxazole) fiber, 20 to 30 parts of light-burned magnesium oxide, and 5 to 10 parts of nanocellulose; wherein the GHL powder comprises polyacrylamide and modified tuff-limestone mineral powder.

[0007] Further, the tuff-limestone powder is modified by the following method: Mix 40-50 parts of limestone and 40-50 parts of tuff, roll and then grind into powder, sieve to obtain a mixed powder with a particle size less than 0.075 mm, heat to 70-90 °C, add a modifier containing stearic acid, stir evenly for 1-3 h and then stop the reaction, filter the slurry and dry it at 110-130 °C for 3-5 h, use a blender to disperse the dried product, and sieve to obtain the modified tuff-limestone powder with a particle size less than 0.075 mm.

[0008] Furthermore, the modifier containing stearic acid comprises the following components: by weight, 80-90 parts of water, 5-8 parts of stearic acid, 2-3 parts of sodium hydroxide, and 1-2 parts of calcium hydroxide.

[0009] Furthermore, the preparation method of the modifier containing stearic acid is: Mix the components of the modifier and carry out a saponification reaction at 80-95 °C for 1-3 h to obtain the modifier.

[0010] Furthermore, the GHL powder comprises the following components: by weight, 60-80 parts of modified tuff-limestone powder, and 5-20 parts of polyacrylamide powder.

[0011] Among them, the preparation method of the GHL powder is: Mechanically mix the modified tuff-limestone powder and polyacrylamide powder for 5 min to obtain the GHL powder.

[0012] Preferably, the diameter of the poly(p-phenylene benzobisoxazole) fiber is 10-25 μm, the length is 3-19 mm; the calcination temperature of the light-burned magnesia is 700-800 °C; the diameter of the nanocellulose is 10-50 nm.

[0013] For the anti-corrosion performance admixture of concrete of the present invention, the polyacrylamide in the GHL powder improves the viscosity of the concrete and enhances the water retention effect of the concrete. The modified tuff-limestone powder not only plays a filling role in the concrete, but also due to its increased hydrophobicity after modification, it reduces water evaporation, reduces drying shrinkage and the generation of microcracks. The poly(p-phenylene benzobisoxazole) fiber has high strength, high modulus and alkali resistance stability, and combines well with the concrete, effectively reducing the generation of macroscopic cracks in the concrete. The light-burned magnesia expands after hydration and has the effect of compensating for the shrinkage of the concrete. The nanocellulose inhibits the early hydration of the cement and promotes the later hydration of the cement, effectively improving the microstructure of the concrete and inhibiting the generation of microcracks. Each component of the anti-corrosion performance admixture of concrete of the present invention acts synergistically, improving the compactness of the concrete, reducing the erosion of environmental water, and enhancing the anti-corrosion performance of hydraulic concrete.

[0014] On the other hand, the present invention provides a method for preparing the above concrete anti-corrosion additive, and the preparation method is as follows: the raw material components of the concrete anti-corrosion additive are mechanically mixed evenly in a stirrer to obtain the concrete anti-corrosion additive. Specifically, by mass parts, 40-50 parts of limestone and 40-50 parts of tuff are mixed, rolled and then ground into powder, and the mixed powder with a particle size less than 0.075 mm is obtained by screening, heated to 70-90 °C, and after adding a modifier containing stearic acid, the mixture is evenly stirred for 1-3 h and then the reaction is stopped. The slurry is filtered by suction and dried at 110-130 °C for 3-5 h, and the dried product is dispersed by a stirrer and screened to obtain a modified tuff-limestone powder with a particle size less than 0.075 mm. 60-80 parts of the modified tuff-limestone powder and 5-20 parts of polyacrylamide powder are mechanically mixed for 5 min to obtain GHL powder. 40-50 parts of GHL powder, 45-55 parts of poly(p-phenylene benzobisoxazole) fiber, 20-30 parts of light-burned magnesia, and 5-10 parts of nanocellulose are mechanically mixed evenly in a stirrer for 15-30 min to obtain the concrete anti-corrosion additive.

[0015] On the other hand, the present invention provides a method for using the above concrete anti-corrosion additive. The additive is added after the concrete is wet-stirred for 1 min, and the dosage is 1.0-5.0 kg per cubic meter of concrete.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0017] (1) The polyacrylamide powder in the GHL powder of the present invention has the function of improving the viscosity of concrete and enhancing the hydrophobicity of concrete; the modified tuff-limestone powder not only plays a filling role in concrete, but also increases the surface tension of capillary pores after modification, reduces water evaporation, reduces drying shrinkage and the generation of microcracks;

[0018] (2) The poly(p-phenylene benzobisoxazole) fiber of the present invention has high strength, high modulus and alkali resistance stability, and combines well with concrete, effectively reducing the generation of macroscopic cracks in concrete;

[0019] (3) The light-burned magnesia of the present invention generates expansion after hydration, which has the effect of compensating for the shrinkage of concrete.

[0020] (3) The nanocellulose of the present invention inhibits the early hydration of cement, promotes the later hydration of cement, effectively improves the microstructure of concrete, and inhibits the generation of microcracks;

[0021] (4) The components of the concrete anti-corrosion additive of the present invention act synergistically, improve the compactness of concrete, reduce the erosion of environmental water, and improve the anti-corrosion performance of hydraulic concrete. Specific embodiments

[0022] Example 1

[0023] This example provides a concrete anti-corrosion additive. The additive includes the following components: by weight, 50 parts of GHL powder, 45 parts of poly(p-phenylene benzobisoxazole) fiber, 20 parts of light-burned magnesia, and 10 parts of nanocellulose. Among them, the diameter of the poly(p-phenylene benzobisoxazole) fiber is 10 - 25 μm, and the length is 3 - 19 mm; the diameter of the nanocellulose is 10 - 50 nm, and the calcination temperature of the light-burned magnesia is 700 °C.

[0024] The preparation method of the concrete anti-corrosion additive in this example is: by weight, mix 50 parts of GHL powder, 45 parts of poly(p-phenylene benzobisoxazole) fiber, 20 parts of light-burned magnesia, and 10 parts of nanocellulose mechanically in a stirrer for 15 - 30 min to obtain the concrete anti-corrosion additive.

[0025] Among them, the GHL powder includes the following components: by weight fraction, mix 60 parts of modified tuff-limestone powder and 20 parts of polyacrylamide powder. The preparation method of the GHL powder is: mix 40 parts of limestone and 50 parts of tuff, roll and grind into powder, sieve to obtain a mixed powder with a particle size less than 0.075 mm, heat to 70 - 90 °C, add a modifier containing stearic acid, stir evenly for 1 - 3 h and then stop the reaction, filter the slurry and dry it at 110 - 130 °C for 3 - 5 h, use a stirrer to disperse the dried product, and sieve to obtain the modified tuff-limestone powder with a particle size less than 0.075 mm. Mechanically mix the modified tuff-limestone powder and polyacrylamide powder for 5 min to obtain the GHL powder.

[0026] Among them, the modifier containing stearic acid includes the following components: by weight, 80 parts of water, 8 parts of stearic acid, 3 parts of sodium hydroxide, and 2 parts of calcium hydroxide.

[0027] This example provides a concrete anti-corrosion additive. Add the additive to the ordinary concrete after wet mixing for 1 min, and the dosage is 3.0 kg per cubic meter of concrete. The ordinary concrete includes the following components: cement, water, sand, small stones (5 - 20 mm), large stones (20 - 40 mm), and water reducer.

[0028] Example 2

[0029] This example provides a concrete anti-corrosion additive. The additive includes the following components: by weight, 40 parts of GHL powder, 55 parts of poly(p-phenylene benzobisoxazole) fiber, 30 parts of light-burned magnesia, and 10 parts of nanocellulose. Among them, the diameter of the poly(p-phenylene benzobisoxazole) fiber is 10 - 25 μm, and the length is 3 - 19 mm; the diameter of the nanocellulose is 10 - 50 nm; the calcination temperature of the light-burned magnesia is 700 °C.

[0030] The preparation method of the concrete anti-corrosion additive in this embodiment is as follows: by weight, 40 parts of GHL powder, 55 parts of poly(p-phenylene benzobisoxazole) fiber, 30 parts of light-burned magnesia, and 5 parts of nanocellulose are mechanically mixed evenly in a stirrer for 15 - 30 minutes to obtain the concrete anti-corrosion additive.

[0031] Among them, the GHL powder includes the following components: by weight fraction, 80 parts of modified tuff-limestone powder and 5 parts of polyacrylamide powder. The preparation method of the GHL powder is: 50 parts of limestone and 40 parts of tuff are mixed, rolled and then ground into powder, screened to obtain a mixed powder with a particle size less than 0.075 mm, heated to 70 - 90 °C, after adding a modifier containing stearic acid, stirred evenly for 1 - 3 hours and then the reaction is stopped. The slurry is filtered by suction and dried at 110 - 130 °C for 3 - 5 hours, and the dried product is dispersed by a stirrer and screened to obtain modified tuff-limestone powder with a particle size less than 0.075 mm. The modified tuff-limestone powder and polyacrylamide powder are mechanically mixed for 5 minutes to obtain the GHL powder.

[0032] Among them, the modifier containing stearic acid contains the following components: by weight, 90 parts of water, 5 parts of stearic acid, 2 parts of sodium hydroxide, and 1 part of calcium hydroxide.

[0033] This embodiment provides a concrete anti-corrosion additive. The additive is added after the ordinary concrete is wet-stirred for 1 minute, and the dosage is 3.0 kg per cubic meter of concrete. The ordinary concrete includes the following components: cement, water, sand, small stones (5 - 20 mm), large stones (20 - 40 mm), and water reducer.

[0034] Example 3

[0035] This embodiment provides a concrete anti-corrosion additive. The additive includes the following components: by weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of light-burned magnesia, and 8 parts of nanocellulose. Among them, the diameter of the poly(p-phenylene benzobisoxazole) fiber is 10 - 25 μm, and the length is 3 - 19 mm; the diameter of the nanocellulose is 10 - 50 nm; the calcination temperature of the light-burned magnesia is 700 °C.

[0036] The preparation method of the concrete anti-corrosion additive in this embodiment is as follows: by weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of light-burned magnesia, and 8 parts of nanocellulose are mechanically mixed evenly in a stirrer for 15 - 30 minutes to obtain the concrete anti-corrosion additive.

[0037] Among them, the GHL powder includes the following components: by weight fraction, 70 parts of modified tuff-limestone powder and 12 parts of polyacrylamide powder. The preparation method of the GHL powder is as follows: mix 50 parts of limestone and 50 parts of tuff, roll and then grind into powder, screen to obtain a mixed powder with a particle size less than 0.075 mm, heat to 70-90 °C, add a modifier containing stearic acid, stir evenly for 1-3 h and then stop the reaction, filter the slurry and dry it at 110-130 °C for 3-5 h, use a stirrer to disperse the dried product, and screen to obtain modified tuff-limestone powder with a particle size less than 0.075 mm. Mechanically mix the modified tuff-limestone powder and polyacrylamide powder for 5 min to obtain the GHL powder.

[0038] Among them, the modifier containing stearic acid includes the following components: by weight, 85 parts of water, 6 parts of stearic acid, 2 parts of sodium hydroxide, and 2 parts of calcium hydroxide.

[0039] This embodiment provides a concrete anti-corrosion additive. The additive is added after the ordinary concrete is wet-stirred for 1 min, and the dosage is 3.0 kg per cubic meter of concrete. The ordinary concrete includes the following components: cement, water, sand, small stones (5-20 mm), large stones (20-40 mm), and water reducer.

[0040] Comparative Example 1

[0041] Compared with Example 3, the difference in this comparative example is that the GHL powder is not incorporated in this comparative example. Specifically, the additive includes the following components: by weight, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of light-burned magnesia, and 8 parts of nanocellulose.

[0042] By weight, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of light-burned magnesia, and 8 parts of nanocellulose are mechanically mixed in a blender for 15-30 min to obtain an additive without GHL powder, and 3.0 kg of this additive is incorporated per cubic meter of concrete.

[0043] Comparative Example 2

[0044] Compared with Example 3, the difference in this comparative example is that the poly(p-phenylene benzobisoxazole) fiber is not incorporated in this comparative example. Specifically, the additive includes the following components: by weight, 45 parts of GHL powder, 25 parts of light-burned magnesia, and 8 parts of nanocellulose.

[0045] By weight, 45 parts of GHL powder, 25 parts of light-burned magnesia, and 8 parts of nanocellulose are mechanically mixed in a blender for 15-30 min to obtain an additive without poly(p-phenylene benzobisoxazole) fiber, and 3.0 kg of this additive is incorporated per cubic meter of concrete. The preparation method of the GHL powder is the same as that in Example 3.

[0046] Comparative Example 3

[0047] Compared with Example 3, the difference in this comparative example is that this comparative example does not incorporate lightly burned magnesium oxide. Specifically, the admixture includes the following components: by weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, and 8 parts of nanocellulose.

[0048] By weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, and 8 parts of nanocellulose are mechanically mixed in a blender for 15 - 30 min to obtain the admixture, and 3.0 kg of this admixture is incorporated into each cubic meter of concrete. The preparation method of GHL powder is the same as that in Example 3.

[0049] Comparative Example 4

[0050] Compared with Example 3, the difference in this comparative example is that this comparative example does not incorporate nanocellulose. Specifically, the admixture includes the following components: by weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, and 25 parts of lightly burned magnesium oxide.

[0051] By weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, and 25 parts of lightly burned magnesium oxide are mechanically mixed in a blender for 15 - 30 min to obtain the admixture without nanocellulose, and 3.0 kg of this admixture is incorporated into each cubic meter of concrete. The preparation method of GHL powder is the same as that in Example 3.

[0052] Comparative Example 5

[0053] Compared with Example 3, the difference in this comparative example is that 1.0 kg of this admixture is incorporated into each cubic meter of concrete. Specifically, the admixture includes the following components: by weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of lightly burned magnesium oxide, and 8 parts of nanocellulose.

[0054] By weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of lightly burned magnesium oxide, and 8 parts of nanocellulose are mechanically mixed in a blender for 15 - 30 min to obtain the admixture, and 1.0 kg of this admixture is incorporated into each cubic meter of concrete. The preparation method of GHL powder is the same as that in Example 3.

[0055] Comparative Example 6

[0056] Compared with Example 3, the difference in this comparative example is that 5.0 kg of this admixture is incorporated into each cubic meter of concrete. Specifically, the admixture includes the following components: by weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of lightly burned magnesium oxide, and 8 parts of nanocellulose.

[0057] By weight, 45 parts of GHL powder, 50 parts of poly(p-phenylene benzobisoxazole) fiber, 25 parts of light-burned magnesia and 8 parts of nanocellulose were mechanically mixed in a blender for 15 - 30 min to obtain an admixture, and 5.0 kg of this admixture was incorporated into each cubic meter of concrete. The preparation method of GHL powder was the same as that in Example 3.

[0058] Test on anti-corrosion performance

[0059] The specimen without admixture was used as the blank sample. According to the Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete (GB / T 50082 - 2009), the corrosion depth, mass loss rate and flexural strength of the concrete specimens after corrosion in 6.0 mol / L NH4Cl solution were tested. The concrete mix proportion is shown in Table 1, the test results of corrosion depth are shown in Table 2, the test results of mass loss rate are shown in Table 3, and the test results of flexural strength are shown in Table 4.

[0060] Table 1 Concrete mix proportion

[0061]

[0062] Table 2 Test results of corrosion depth

[0063]

[0064]

[0065] Table 3 Test results of mass loss rate

[0066]

[0067] Table 3 Test results of flexural strength

[0068]

[0069] From the above test results, it can be seen that compared with the blank group, the incorporation of the anti-corrosion admixture of the present invention reduces the corrosion depth and strength loss after corrosion of the concrete, and has the effect of significantly improving the anti-corrosion performance of the concrete. Among the three examples, the effect of Example 3 is the best. At 7 d, 28 d and 90 d of corrosion, the corrosion depth is reduced by 52.9%, 42.1% and 35.7% respectively, the mass loss rate is reduced by 85.7%, 70.3% and 43.6% respectively, and the flexural strength is increased by 22.7%, 43.3% and 52.6% respectively. Compared with the examples, the anti-corrosion performance in the comparative examples all decreases. Therefore, the mix proportion of Example 3 is the most preferred mix proportion, and 3.0 kg / m 3 is the optimal dosage.

[0070] The above are all preferred embodiments of the present invention, and do not limit the protection scope of this application. Any modifications, equivalent replacements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A concrete anti-corrosion admixture, characterized in that: The admixture comprises the following components: by weight, 40 to 50 parts of GHL powder, 45 to 55 parts of poly(p-phenylene benzobisoxazole) fibers, 20 to 30 parts of light-burned magnesium oxide, and 5 to 10 parts of nanocellulose; The GHL powder includes polyacrylamide and modified tuff-limestone powder. The modified tuff-limestone powder is prepared by mixing 40-50 parts of limestone and 40-50 parts of tuff, crushing and grinding to obtain a mixed powder; heating the mixed powder to 70-90°C, then adding a modifier containing stearic acid, and reacting for a period of time. After the reaction is completed, the obtained product is filtered, dried and sieved to obtain the modified tuff-limestone powder.

2. The concrete anti-corrosion admixture according to claim 1, characterized in that: The reaction time of adding the modifier containing stearic acid to the mixed powder is 1-3 hours.

3. The concrete anti-corrosion admixture according to claim 1, characterized in that: The modifier containing stearic acid comprises the following components: by weight, 80-90 parts of water, 5-8 parts of stearic acid, 2-3 parts of sodium hydroxide, and 1-2 parts of calcium hydroxide.

4. The concrete anti-corrosion admixture according to claim 1, characterized in that: The preparation method of the modifier containing stearic acid comprises the following steps: mixing various components of the modifier, performing saponification reaction at 80-95° C. for 1-3 hours, and obtaining the modifier containing stearic acid.

5. The concrete anti-corrosion admixture according to claim 1, characterized in that: The GHL powder comprises the following components: by weight, 60 to 80 parts of modified tuff-limestone mineral powder and 5 to 20 parts of polyacrylamide powder.

6. The concrete anti-corrosion admixture according to claim 5, characterized in that: The preparation method of GHL powder is as follows: modified tuff-limestone mineral powder and polyacrylamide powder are mechanically mixed to obtain GHL powder.

7. The concrete anti-corrosion admixture according to claim 1, characterized in that: The diameter of the poly(p-phenylene benzobisoxazole) fiber is 10-25 μm, and the length is 3-19 mm; the calcination temperature of the light-burned magnesium oxide is 700-800° C.; and the diameter of the nanocellulose is 10-50 nm.

8. A method for preparing the concrete anti-corrosion admixture according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: mechanically mixing various component raw materials of the concrete anti-corrosion admixture in a stirrer to obtain the concrete anti-corrosion admixture.

9. A method for using the concrete anti-corrosion admixture according to any one of claims 1 to 7, characterized in that: After wet mixing of concrete, add concrete anti-corrosion admixture in a dosage of 1.0~5.0kg per cubic meter of concrete.

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