Corrosion-resistant concrete additive and preparation method thereof

Abstract

The invention relates to the technical field of concrete additives, and discloses a corrosion-resistant concrete additive and a preparation method thereof.The corrosion-resistant concrete additive is prepared from pyrophosphoric acid modified kaolin, sulfonated polymethyl vinyl ether and water; wherein the pyrophosphoric acid modified kaolin is prepared by reacting triammonium citrate modified kaolin with pyrophosphoric acid under the action of a water-carrying agent; the triammonium citrate modified kaolin is prepared by dispersing kaolin in deionized water and adding triammonium citrate to perform intercalation modification on the kaolin; the sulfonated polymethyl vinyl ether is prepared by reacting polymethyl vinyl ether maleic anhydride with 2-aminoethanesulfonic acid under the catalytic action of ferric chloride. When the concrete additive acts on concrete, the mechanical strength and corrosion resistance of the concrete can be enhanced, the application field of the concrete is effectively expanded, the durability of the concrete is enhanced, and the concrete has longer service life.

Description

Technical Field

[0001] The invention relates to the technical field of concrete additives, and in particular to a corrosion-resistant concrete additive and a preparation method thereof. Background Art

[0002] Concrete is an indispensable building material in modern buildings. It is generally mixed with various additives such as cement, sand and gravel. Among them, concrete additives, as an important component affecting the quality of concrete products, have a profound impact on the compressive strength and corrosion resistance of concrete. Nowadays, with the continuous development and innovation of modern engineering, the improvement of the compressive strength and corrosion resistance of concrete by ordinary concrete additives can no longer meet the needs of modern engineering development, especially in harsh environments. Ordinary concrete additives have limited protection for concrete, especially in highly corrosive environments such as marine engineering and chemical facilities. The durability of concrete is not strong, which greatly limits the scope of application and service life of concrete in actual engineering.

[0003] The patent with publication number CN103755216B discloses a method for preparing a composite concrete additive. The raw materials of the composite concrete additive are alunite, dickite, zeolite powder, montmorillonite, sodium bentonite, fly ash, calcium fluoride, sucrose, polyvinyl alcohol, methyl cellulose, sodium carbonate, gypsum, sodium silicate, aluminum powder, and boric acid. The raw materials of the concrete additive prepared by the invention are easy to obtain, the production process is simple, the use process is convenient and can be used evenly, the production stability is met, the quality of the produced concrete is effectively guaranteed, and the prepared concrete has excellent mechanical strength. However, the corrosion resistance of the concrete made by the concrete additive prepared by the patent needs to be improved, which greatly limits the application field of the concrete. Summary of the invention

[0004] The purpose of the present invention is to provide a corrosion-resistant concrete additive and a preparation method thereof, which solves the problem that when ordinary concrete additives act on concrete, the prepared concrete has general compressive strength and poor corrosion resistance.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A corrosion-resistant concrete additive comprises the following raw materials in parts by weight: 30-40 parts of pyrophosphate-modified kaolin, 20-30 parts of sulfonated polymethyl vinyl ether, and 150-180 parts of water; the pyrophosphate-modified kaolin is prepared by reacting triammonium citrate-modified kaolin with pyrophosphate under the action of a water-carrying agent; the triammonium citrate-modified kaolin is prepared by dispersing kaolin in deionized water and adding triammonium citrate to perform intercalation modification; the sulfonated polymethyl vinyl ether is prepared by reacting polymethyl vinyl ether maleic anhydride with 2-aminoethane sulfonic acid under the catalytic action of ferric chloride.

[0006] Furthermore, the preparation method of the pyrophosphate-modified kaolin comprises the following steps: S1: Place kaolin in deionized water, ultrasonically disperse for 10-15 minutes, add triammonium citrate, heat and mix thoroughly, filter, wash and dry to obtain triammonium citrate modified kaolin; S2: Place the triammonium citrate modified kaolin in anhydrous ethanol, ultrasonically disperse for 5-10 minutes, add pyrophosphoric acid and a water-carrying agent, mix well, heat up and reflux for reaction, collect the product after cooling to room temperature, and obtain pyrophosphoric acid modified kaolin.

[0007] In this scheme, kaolin is ultrasonically dispersed in deionized water and then triammonium citrate is added. The structure of triammonium citrate contains quaternary ammonium groups, which can undergo ion exchange reactions with the interlayers of kaolin, so that triammonium citrate is inserted into the interlayers of kaolin to obtain triammonium citrate-modified kaolin. At the same time, the structure of this triammonium citrate-modified kaolin has active hydroxyl groups that can react with the phosphate groups in the pyrophosphate structure under the promotion of the water-carrying agent to obtain pyrophosphate-modified kaolin. This pyrophosphate-modified kaolin uses kaolin as a base material, has good adsorption, and can effectively enhance the cohesiveness and water retention of concrete. The use of triammonium citrate intercalated kaolin can not only promote the dispersion of kaolin in concrete, but also enhance the bonding ability with concrete. The pyrophosphate in its structure can enhance the water retention capacity of concrete and the strength of concrete. The formed phosphate groups can produce ion exchange reactions with hydroxides in an alkaline environment, reduce the concentration of alkaline substances, consume them, and improve the corrosion resistance of concrete.

[0008] Furthermore, in step S1, the temperature of the heating and sufficient mixing and stirring is 45-50°C and the time is 3-5h.

[0009] Furthermore, in step S2, the water-carrying agent is cyclohexane.

[0010] Furthermore, in step S2, the time of the temperature rising reflux reaction is 8-10 hours.

[0011] Furthermore, the preparation method of the sulfonated polymethyl vinyl ether comprises the following steps: Polymethyl vinyl ether maleic anhydride is placed in N,N-dimethylformamide, 2-aminoethanesulfonic acid and a catalyst are added after ultrasonic oscillation, the temperature is raised to 95-100°C and stirred for reaction for 2-3 hours, and low-boiling substances are removed by vacuum distillation to obtain sulfonated polymethyl vinyl ether.

[0012] In this scheme, under the action of a catalyst, the anhydride group in the maleic anhydride structure of polymethyl vinyl ether and the amino group in the 2-aminoethane sulfonic acid structure undergo a ring-opening reaction to obtain a sulfonated polymethyl vinyl ether with a carboxyl group and a sulfonic acid group. The sulfonated polymethyl vinyl ether has a plurality of sulfonic acid groups in its structure, has good salt resistance and acid resistance, and can effectively improve the corrosion resistance of concrete. At the same time, the plurality of carboxyl groups in its structure can chelate with calcium ions in the concrete slurry to form nanoparticles to fill the holes in the concrete, produce barrier properties, effectively block the invasion of corrosive media, and improve the corrosion resistance of concrete. Through the combination of the sulfonic acid group and the carboxyl group, the two produce a synergistic effect, and jointly enhance the corrosion resistance of the concrete, so that it has a long service life.

[0013] Furthermore, the power of the ultrasonic oscillation is 500-600W, and the time is 1-1.5h.

[0014] Furthermore, the catalyst is ferric chloride.

[0015] A method for preparing a corrosion-resistant concrete additive comprises the following steps: The pyrophosphate-modified kaolin is placed in water, ultrasonically dispersed for 15-20 minutes, sulfonated polymethyl vinyl ether is added, and the mixture is fully stirred for 1-2 hours. The product is collected to obtain a concrete additive.

[0016] Through the above technical scheme, pyrophosphate-modified kaolin is used in combination with sulfonated polymethyl vinyl ether, and an anti-corrosion effect is produced through the formed phosphate ester group. At the same time, a synergistic effect is produced with the sulfonic acid group and the carboxyl group in the structure of the sulfonated polymethyl vinyl ether, producing the same effect from different directions, thereby jointly improving the ability of concrete additives to enhance the anti-corrosion performance of concrete.

[0017] Beneficial effects of the present invention: The present invention participates in the preparation process of the corrosion-resistant concrete additive by preparing pyrophosphate-modified kaolin and sulfonated polymethyl vinyl ether. When the pyrophosphate-modified kaolin and sulfonated polymethyl vinyl ether are applied to concrete, the strength and corrosion resistance of the concrete can be effectively enhanced, the applicable field of the concrete can be effectively expanded, the durability of the concrete can be enhanced, and the concrete can have a longer service life.

[0018] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 The present invention is a flow chart of the preparation of the concrete additive. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The preparation methods of sulfonated polymethyl vinyl ether and pyrophosphate modified kaolin in the following examples and comparative examples of the present invention are as follows: 1. Preparation of sulfonated polymethyl vinyl ether 3 g of polymethyl vinyl ether maleic anhydride was placed in 80 ml of N,N-dimethylformamide, and 500 W ultrasonic oscillation was applied for 1 hour. Then, 2.6 g of 2-aminoethanesulfonic acid and 0.03 g of ferric chloride were added. The temperature was raised to 95 ° C and stirred for 2 hours. Low boiling materials were removed by vacuum distillation to obtain sulfonated polymethyl vinyl ether.

[0023] Through the above technical solution, the anhydride group in the maleic anhydride structure of polymethyl vinyl ether and the amino group in the 2-aminoethane sulfonic acid structure undergo a ring-opening reaction to obtain sulfonated polymethyl vinyl ether with carboxyl groups and sulfonic acid groups. The sulfonated polymethyl vinyl ether has multiple sulfonic acid groups in its structure, has good salt resistance and acid resistance, and can effectively improve the corrosion resistance of concrete. At the same time, the multiple carboxyl groups in its structure can chelate with calcium ions in the concrete slurry to form nanoparticles to fill the concrete pores, enhance the barrier properties of the concrete, effectively block the invasion of corrosive media, and enhance the corrosion resistance of the concrete. Through the combination of the sulfonic acid group and the carboxyl group, a synergistic effect is generated to jointly enhance the corrosion resistance of the concrete.

[0024] 2. Preparation of pyrophosphate-modified kaolin S1: 5 g of kaolin was placed in 100 ml of deionized water, and after ultrasonic dispersion for 10 min, 3 g of triammonium citrate was added, and the mixture was heated to 45 °C and stirred for 3 h. After filtering, washing and drying, triammonium citrate modified kaolin was obtained; S2: 5.5 g of triammonium citrate modified kaolin was placed in 120 ml of anhydrous ethanol, and after ultrasonic dispersion for 5 minutes, 5 g of pyrophosphoric acid and 3 g of cyclohexane were added, mixed evenly, and refluxed at elevated temperature for 8 hours. After cooling to room temperature, the product was collected to obtain pyrophosphoric acid modified kaolin.

[0025] Through the above technical scheme, kaolin is ultrasonically dispersed in deionized water and then triammonium citrate is added. Since the triammonium citrate structure contains quaternary ammonium groups, it can undergo ion exchange reactions with the interlayers of kaolin, so that the triammonium citrate is inserted into the interlayers of kaolin to obtain triammonium citrate modified kaolin. At the same time, the triammonium citrate modified kaolin structure has active hydroxyl groups that can react with the phosphate groups in the pyrophosphate structure under the promotion of the water-carrying agent to obtain pyrophosphate modified kaolin. This pyrophosphate modified kaolin uses kaolin as a substrate, has good adsorption, and can effectively enhance the cohesiveness and water retention of concrete. The use of triammonium citrate intercalated kaolin can not only promote the dispersion of kaolin in concrete, but also enhance the bonding ability with concrete. The pyrophosphate in its structure can enhance the water retention capacity of concrete and enhance the strength of concrete. The formed phosphate group can produce ion exchange reactions with hydroxides in an alkaline environment, reduce the concentration of alkaline substances, consume them, and improve the corrosion resistance of concrete. Example 1

[0026] Preparation of concrete additives 30 parts of pyrophosphate-modified kaolin were placed in 150 parts of water, and ultrasonically dispersed for 15 minutes. 20 parts of sulfonated polymethyl vinyl ether were added, and the mixture was fully stirred for 1 hour. The product was collected to obtain a concrete additive. Example 2

[0027] Preparation of concrete additives 35 parts of pyrophosphate-modified kaolin were placed in 165 parts of water, and ultrasonically dispersed for 18 minutes. 25 parts of sulfonated polymethyl vinyl ether were added, and the mixture was fully stirred for 1.5 hours. The product was collected to obtain a concrete additive. Example 3

[0028] Preparation of concrete additives 40 parts of pyrophosphate-modified kaolin were placed in 180 parts of water, and ultrasonically dispersed for 20 minutes. 30 parts of sulfonated polymethyl vinyl ether were added, and the mixture was fully stirred for 2 hours. The product was collected to obtain a concrete additive.

[0029] Comparative Example 1 Preparation of concrete additives 25 parts of sulfonated polymethyl vinyl ether were placed in 165 parts of water, and the mixture was stirred for 1.5 hours. The product was collected to obtain a concrete additive.

[0030] Comparative Example 2 Preparation of concrete additives 35 parts of pyrophosphate-modified kaolin were placed in 165 parts of water, ultrasonically dispersed for 18 minutes, fully stirred for 1.5 hours, and the product was collected to obtain a concrete additive.

[0031] Comparative Example 3 Preparation of concrete additives 35 parts of triammonium citrate modified kaolin were placed in 165 parts of water, and ultrasonically dispersed for 18 minutes. 25 parts of sulfonated polymethyl vinyl ether were added, and the mixture was fully stirred for 1.5 hours. The product was collected to obtain a concrete additive.

[0032] Performance Testing 10kg cement, 1.5kg fly ash, 18kg sand and gravel, 13kg water and 0.5kg concrete additive were added into a mixer, fully mixed and stirred for 10 minutes to obtain concrete, molded and vibrated, and placed at room temperature for 48 hours before demolding to obtain concrete test blocks; the obtained concrete test blocks were cured for 28 days in a standard environment with a temperature of 20°C and a relative humidity of more than 95% as samples; the compressive and corrosion resistance of the samples were tested with reference to the standards GB / T50107-2010 "Concrete Strength Test and Evaluation Standard" and GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete"; the specific test results are shown in the following table:

[0033] It can be seen from the above table that the samples prepared in Examples 1 to 3 all have excellent compressive resistance and corrosion resistance. The concrete additive added to the sample prepared in Comparative Example 1 did not add pyrophosphate-modified kaolin during preparation, so the corrosion resistance and compressive strength were average. The concrete additive added to the sample prepared in Comparative Example 2 did not add sulfonated polymethyl vinyl ether during preparation, and the corrosion resistance was good, but the compressive strength was average. The concrete additive added to the sample prepared in Comparative Example 3 directly added triammonium citrate-modified kaolin and sulfonated polymethyl vinyl ether during preparation, and the compressive strength was excellent, but the erosion resistance was not as good as that of the examples, because the triammonium citrate-modified kaolin did not further react with pyrophosphate.

[0034] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0035] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A corrosion-resistant concrete additive, characterized in that: The invention comprises the following raw materials in parts by weight: 30-40 parts of pyrophosphate-modified kaolin, 20-30 parts of sulfonated polymethyl vinyl ether and 150-180 parts of water; the pyrophosphate-modified kaolin is prepared by reacting triammonium citrate-modified kaolin with pyrophosphate under the action of a water-carrying agent; the triammonium citrate-modified kaolin is prepared by dispersing kaolin in deionized water and adding triammonium citrate to perform intercalation modification; the sulfonated polymethyl vinyl ether is prepared by reacting polymethyl vinyl ether maleic anhydride with 2-aminoethane sulfonic acid under the catalytic action of ferric chloride.

2. A corrosion-resistant concrete additive according to claim 1, characterized in that: The preparation method of the pyrophosphate-modified kaolin comprises the following steps: S1: Place kaolin in deionized water, ultrasonically disperse for 10-15 minutes, add triammonium citrate, heat and mix thoroughly, filter, wash and dry to obtain triammonium citrate modified kaolin; S2: Place the triammonium citrate modified kaolin in anhydrous ethanol, ultrasonically disperse for 5-10 minutes, add pyrophosphoric acid and a water-carrying agent, mix well, heat up and reflux for reaction, collect the product after cooling to room temperature, and obtain pyrophosphoric acid modified kaolin.

3. A corrosion-resistant concrete additive according to claim 2, characterized in that: In step S1, the temperature for heating and fully mixing is 45-50°C and the time is 3-5h.

4. A corrosion-resistant concrete additive according to claim 2, characterized in that: In step S2, the water-carrying agent is cyclohexane.

5. The corrosion-resistant concrete additive according to claim 2, characterized in that: In step S2, the temperature rising and reflux reaction time is 8-10 hours.

6. The corrosion-resistant concrete additive according to claim 1, characterized in that: The preparation method of the sulfonated polymethyl vinyl ether comprises the following steps: Polymethyl vinyl ether maleic anhydride is placed in N,N-dimethylformamide, 2-aminoethanesulfonic acid and a catalyst are added after ultrasonic oscillation, the temperature is raised to 95-100°C and stirred for reaction for 2-3 hours, and low-boiling substances are removed by vacuum distillation to obtain sulfonated polymethyl vinyl ether.

7. The corrosion-resistant concrete additive according to claim 6, characterized in that: The power of the ultrasonic oscillation is 500-600W, and the time is 1-1.5h.

8. The corrosion-resistant concrete additive according to claim 6, characterized in that: The catalyst is ferric chloride.

9. A method for preparing the corrosion-resistant concrete additive according to claim 1, characterized in that: The following steps are involved: The pyrophosphate-modified kaolin is placed in water, ultrasonically dispersed for 15-20 minutes, sulfonated polymethyl vinyl ether is added, and the mixture is fully stirred for 1-2 hours. The product is collected to obtain a concrete additive.

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