Concrete foam stabilizer based on quaternary ammonium salt cationized graphene oxide material as well as preparation method and application of concrete foam stabilizer

Abstract

The invention provides a concrete foam stabilizer based on a quaternary ammonium salt cationization graphene oxide material as well as a preparation method and application of the concrete foam stabilizer. The quaternary ammonium salt cationization graphene oxide material is prepared by the following steps: firstly carrying out epoxypropane hydrophobic modification on hydroxyl on the surface of graphene oxide (GO), and then carrying out quaternary ammonium salt cationization; the obtained modified material has positive charges on the surface, and can play an electrostatic adsorption role with an anionic air entraining agent, so that more air entraining agent molecules are adsorbed on the surface of graphene oxide and spread, gather and arrange on a gas-liquid interface to form a continuous network structure, the thickness of an air bubble film is increased, introduced bubbles are stable and not broken, and the air entraining effect is improved. The foam stabilizer has excellent foam stabilizing performance.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, and in particular to a concrete foam stabilizer based on a quaternary ammonium salt cationized graphene oxide material, and a preparation method and application thereof. Background Art

[0002] With the vigorous development of infrastructure construction in my country, people are paying more and more attention to the durability of concrete. The tiny, uniform and closed bubbles in concrete can greatly improve the workability and water retention of concrete mixtures, reduce the slump loss rate, and thus improve the durability of hardened concrete such as frost resistance, impermeability and carbonation resistance. Bubbles are unstable in fresh concrete, often accompanied by the aggregation or rupture of bubbles. The disappearance of bubbles over time is a very complex process involving bubble aggregation and fusion, Ostwald ripening mechanism, etc. The composition of modern cement and concrete is complex and diverse. Due to the influence of salt ions and adsorption, traditional air-entraining agents are easy to chelate with salt ions to form precipitation or be adsorbed by components and become ineffective. The introduced bubbles are uneven in size and easy to rupture, resulting in the fluctuation of concrete air content over time and the degradation of bubble structure, which affects the freeze-thaw resistance, strength and durability of concrete after hardening.

[0003] At present, researchers generally adopt multiple components to develop air entraining agents with good foam stability, but generally there will be two or more compatibility problems. At present, more studies have found that solid particles have an important impact on the stability of bubbles, can cooperate with air entraining agent molecules on the interface, form more stable bubble shells, and can also improve the microstructure after hardening. CN112062500A adds hydrophobic nanoparticles as nano-enhanced particle components in the composite components, which increases the flexibility of the bubble liquid film and the overall stability of the bubble in the concrete. But the nanoparticles used are silicon dioxide, which itself has negative electricity, and there is electrostatic repulsion between the anionic air entraining agents commonly used in concrete, which is not conducive to giving full play to the synergy between the two, and then reduces the foam stabilizing effect of its performance in concrete.

[0004] Therefore, finding a foam stabilizer that has a simple preparation method and can fully exert synergistic effects with the commonly used air-entraining agent in concrete is one of the technologies that needs to be studied at present. Summary of the invention

[0005] Aiming at the problems of poor compatibility of various admixtures in the prior art compounding means, poor synergistic foam stabilization effect of solid particles and air entraining agents, etc., the present application proposes a concrete foam stabilizer based on quaternary ammonium salt cationized graphene oxide material, a preparation method and application thereof, wherein the quaternary ammonium salt cationized graphene oxide material is prepared by first hydrophobically modifying the hydroxyl groups on the surface of graphene oxide (GO) with propylene oxide, and then quaternary ammonium salt cationization thereof; the surface of the obtained modified material has a positive charge, and can exert an electrostatic adsorption effect with the anionic air entraining agent, so that more air entraining agent molecules are adsorbed on the surface of graphene oxide, and spread and aggregate at the gas-liquid interface to form a continuous network structure, increase the thickness of the bubble film, make the introduced bubbles stable and unbroken, and have excellent foam stabilization performance.

[0006] A concrete foam stabilizer based on quaternary ammonium salt cationized graphene oxide material, wherein the concrete foam stabilizer is obtained by firstly hydrophobically modifying the hydroxyl groups on the surface of graphene oxide with propylene oxide to obtain an intermediate A, and then using N,N dialkyl fatty acid to perform a quaternary ammonium salt cationization reaction on the intermediate A;

[0007] The mass ratio of the graphene oxide to propylene oxide is 1:(1-24);

[0008] The mass ratio of the intermediate A and N,N dialkyl fatty acid is 1:(0.1-1.2);

[0009] The structural formula of the concrete foam stabilizer is shown in the following formula (1):

[0010]

[0011] Wherein, m=an integer from 2 to 10; n=an integer from 0 to 5; R1 is CH3 or CH3CH2; R2 is CH3, CH3CH2 or CH3(CH2)2.

[0012] The quaternary ammonium salt graphene oxide material of the present application includes a hydrophobic unit and a hydrophilic group, wherein the hydrophobic unit is composed of an aromatic ring structure in graphene oxide, 2 to 10 propylene oxide hydrophobic units, an alkyl chain containing 1 to 2 carbon atoms (R1), and an alkyl chain containing 1 to 3 carbon atoms (R2), wherein the propylene oxide unit and the alkyl carbon chain are covalently connected to the surface of graphene oxide through chemical bonds, and the hydrophilic structure is a cationic group containing a quaternary ammonium group.

[0013] A larger number of propylene oxides and a longer carbon chain length will cause molecular entanglement, weakening the electrostatic attraction between the propylene oxide and the anionic air-entraining agent and affecting the foam stabilizing effect; a smaller number of propylene oxides and a shorter carbon chain length will result in poorer hydrophobicity, or even turn the material into a hydrophilic material. The molecules of this material will not be distributed at the gas-liquid interface of the bubbles, but will instead remain free in the concrete slurry, losing its original foam stabilizing effect.

[0014] The N,N dialkyl fatty acid is any one of N,N dimethylcarbamic acid, N,N dimethylglycine, N,N dimethylalanine, 4-N,N dimethylaminobutyric acid, diethylcarbamic acid, diethylaminoacetic acid, diethylaminopropionic acid, diethylaminobutyric acid, and diethylaminovaleric acid.

[0015] The density of hydroxyl groups in the above graphene oxide is 0.01 to 0.04 mol / g.

[0016] The preparation method of the quaternary ammonium salt graphene oxide material of the present application firstly reacts the hydroxyl groups on the surface of graphene oxide with propylene oxide under the action of catalyst I to perform a ring-opening polymerization reaction to generate an intermediate A with a hydrophobic segment; intermediate A is modified with N,N dialkyl fatty acid through an esterification reaction under the action of catalyst II to form an intermediate B with strong hydrophobicity, and then intermediate B is reacted with a halogenated alkane to perform quaternary ammonium salt cationization to obtain a concrete foam stabilizer based on quaternary ammonium salt graphene oxide material. The synthesis route is as follows:

[0017]

[0018] Wherein, m=an integer from 2 to 10; n=an integer from 0 to 5; R1=CH3 or CH3CH2; R2=CH3, CH3CH2 or CH3(CH2)2.

[0019] A preparation method of a concrete foam stabilizer based on quaternary ammonium salt cationic graphene oxide material comprises the following steps: (1) dispersing graphene oxide in an organic solvent, adding a catalyst I under nitrogen protection, slowly introducing propylene oxide, cooling, filtering, washing and drying after the reaction is completed to obtain an intermediate A with a hydrophobic segment; (2) dissolving the intermediate A in an organic solvent, adding a catalyst II, slowly adding an N,N dialkyl fatty acid, heating and refluxing, distilling and removing the solvent after the reaction is completed, filtering, washing and drying to obtain an intermediate B with strong hydrophobicity; (3) dissolving the intermediate B in an organic solvent, slowly adding a halogenated alkane, distilling and removing the solvent after the reaction is completed, filtering, washing and drying to obtain a concrete foam stabilizer.

[0020] During the above steps (1), (2), and (3), the mass percentage concentration of graphene oxide, intermediate A, and intermediate B after being dissolved in an organic solvent is 1% to 50%.

[0021] In the above step (1), the catalyst I is any one of sodium methoxide, sodium hydroxide, potassium hydroxide and sodium ethoxide; the amount of the catalyst I is 3-5% of the mass of the graphene oxide.

[0022] In the above step (2), the catalyst II is any one of sodium p-toluenesulfonate, 4-dimethylaminopyridine / N,N'-dicyclohexylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride / N-hydroxysuccinimide; the amount of catalyst II used is 3-10% of the mass of intermediate A.

[0023] In the above step (3), the halogenated alkane is any one of methyl iodide, ethyl iodide, propyl iodide, methyl bromide, ethyl bromide and propyl bromide; the amount of the halogenated alkane used is 0.03 to 0.9 times the mass of the intermediate B.

[0024] The reaction temperature of the above step (1) is 130°C to 160°C, and the reaction time is 1 to 3 hours; the reaction temperature of the above step (2) is 80 to 130°C, and the reaction time is 3 to 5 hours; the reaction temperature of the above step (3) is 70 to 110°C, and the reaction time is 4 to 10 hours.

[0025] The organic solvent used in the above steps (1), (2) and (3) is any one of methanol, ethanol, isopropanol and tetrahydrofuran.

[0026] The concrete foam stabilizer based on quaternary ammonium salt cationic graphene oxide material is used in combination with an anion air entraining agent; the two can be premixed in advance to make the modified material uniformly dispersed in the anion air entraining agent aqueous solution, and the mixed solution is added to the concrete and stirred. The mass ratio of the foam stabilizer to the anion air entraining agent is (0.01-0.5):1; the total amount of the foam stabilizer and the anion air entraining agent is (0.05-1.0) ten thousandths of the total cementitious material mass.

[0027] Compared with the prior art, this application has the following advantages:

[0028] (1) The present application first hydrophobically modifies the hydroxyl groups on the surface of graphene oxide (GO) with propylene oxide, and then cationizes the hydroxyl groups with quaternary ammonium salt; the surface of the modified material obtained has a positive charge, and has several hydrophobic segments connected to the surface of graphene oxide by covalent bonds. This structure overcomes the electrostatic repulsion between the same cationic groups, while shortening the distance between the hydrophobic segments, enhancing their hydrophobic association, making the molecules more closely and orderly arranged at the gas-liquid interface of the bubble, improving the surface activity of the material, and thus achieving a more excellent foam stabilizing effect;

[0029] (2) The positive charge on the surface of the foam stabilizer material of the present application can play an electrostatic adsorption role with the anionic air entraining agent, so that more air entraining agent molecules are adsorbed on the surface of graphene oxide. The two are spread and tightly clustered at the gas-liquid interface to form a continuous network structure, increase the thickness of the bubble film, make the introduced bubbles stable and not broken, and have excellent foam stabilization performance; at the same time, the prepared material has excellent mechanical properties, which helps to improve the strength of concrete. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution 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.

[0031] In the application examples of the present invention, the reactors used are all equipped with a thermometer, a stirrer, and an inert gas inlet, and are all cleaned and dried before use.

[0032] Example 1

[0033] 1 g of graphene oxide (OH density is 0.02 mol / g) was dispersed in 50 g of methanol, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.04 g of sodium methoxide, heated to 140 ° C, and slowly introduced with 4.64 g of propylene oxide. After reacting for 2 h, the temperature was lowered to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m4) with a hydrophobic segment.

[0034] 1 g of intermediate A (GO-m4) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, 0.05 g of DMAP / DCC was added, the temperature was raised to 80 ° C, and then 0.36 g of N, N-dimethylglycine was slowly added. The mixture was heated to reflux and reacted for 4 hours. The temperature was then lowered to 50 ° C, and the solvent was distilled off to obtain a crude product that was filtered, washed with ethanol, and dried to obtain an intermediate B (GO-m4-n2) with strong hydrophobicity.

[0035] 1 g of the intermediate (GO-m4-n2) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, heated to 80°C, and then 0.52 g of ethyl iodide was slowly added. The mixture was heated under reflux for 6 h, and the heating and reflux were stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-m4-n2-CH2CH3).

[0036] Example 2

[0037] 1 g of graphene oxide (OH density is 0.03 mol / g) was dispersed in 60 g of isopropanol, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.03 g of sodium ethoxide, heated to 150 ° C, slowly introduced with 3.48 g of propylene oxide, reacted for 3 h, cooled to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m2) with a hydrophobic segment.

[0038] 1 g of intermediate A (GO-m2) was dissolved in 60 g of isopropanol, put into a reactor with a reflux water separator, 0.038 g of sodium p-toluenesulfonate was added, the temperature was raised to 90°C, and then 0.88 g of N,N-dimethylbutyric acid was slowly added. The mixture was heated to reflux and reacted for 3 hours. The temperature was then lowered to 50°C, and the solvent was distilled off to obtain a crude product which was filtered, washed with ethanol, and dried to obtain an intermediate B (GO-m2-n4) with strong hydrophobicity.

[0039] 1 g of the intermediate (GO-m4-n4) was dissolved in 60 g of isopropanol, put into a reactor with a reflux water separator, heated to 90°C, and then 0.69 g of bromopropane was slowly added. The mixture was heated under reflux for 8 h, and the reflux was stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-m2-n4-(CH2)2CH3).

[0040] Example 3

[0041] 1 g of graphene oxide (OH density is 0.04 mol / g) was dispersed in 80 g of THF, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.05 g of sodium hydroxide, heated to 160 ° C, and slowly introduced with 23.2 g of propylene oxide. After reacting for 3 h, the temperature was lowered to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m10) with a hydrophobic segment.

[0042] 1 g of intermediate A (GO-m10) was dissolved in 80 g of THF, put into a reactor with a reflux water separator, 0.1 g of DMAP / DCC was added, the temperature was raised to 130°C, and then 0.29 g of diethylaminovaleric acid was slowly added. The mixture was heated to reflux and reacted for 1 h, then the temperature was lowered to 50°C, the solvent was distilled off, and the crude product was filtered, washed with ethanol, and dried to obtain intermediate B (GO-m10-n5) with strong hydrophobicity.

[0043] 1 g of the intermediate (GO-m10-n5) was dissolved in 80 g of THF, put into a reactor with a reflux water separator, heated to 70°C, and then 0.28 g of iodopropane was slowly added. The mixture was heated to reflux for 10 h, and the heating and reflux were stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-m10-n5-(CH2)2CH3).

[0044] Example 4

[0045] 1 g of graphene oxide (OH density is 0.01 mol / g) was dispersed in 100 g of ethanol, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.035 g of potassium hydroxide, heated to 130 ° C, and slowly introduced with 1.16 g of propylene oxide. After reacting for 1.5 h, the temperature was lowered to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m2) with a hydrophobic segment.

[0046] 1 g of intermediate A (GO-m2) was dissolved in 100 g of ethanol, put into a reactor with a reflux water separator, 0.06 g of DMAP / DCC was added, the temperature was raised to 80°C, and then 0.41 g of N,N-dimethylcarbamic acid was slowly added. The mixture was heated to reflux and reacted for 3.5 h. The temperature was then lowered to 50°C, and the solvent was distilled off to obtain a crude product which was filtered, washed with ethanol, and dried to obtain an intermediate B (GO-m2-n0) with strong hydrophobicity.

[0047] 1 g of the intermediate (GO-m2-n0) was dissolved in 100 g of ethanol, put into a reactor with a reflux water separator, heated to 100°C, and then 0.37 g of methyl bromide was slowly added. The reaction was heated to reflux for 5 h, and the heating and reflux were stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-m2-n0-CH3).

[0048] Example 5

[0049] 1 g of graphene oxide (OH density is 0.025 mol / g) was dispersed in 50 g of methanol, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.05 g of sodium hydroxide, heated to 150 ° C, and slowly introduced with 11.6 g of propylene oxide. After reacting for 2 h, the temperature was lowered to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m8) with a hydrophobic segment.

[0050] 1 g of intermediate A (GO-m8) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, 0.09 g of sodium p-toluenesulfonate was added, the temperature was raised to 100 ° C, and then 0.23 g of diethylcarbamic acid was slowly added. The mixture was heated to reflux and reacted for 4 hours. The temperature was then lowered to 50 ° C, and the solvent was distilled off to obtain a crude product that was filtered, washed with ethanol, and dried to obtain an intermediate B (GO-m8-n0) with strong hydrophobicity.

[0051] 1 g of the intermediate (GO-m8-n0) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, heated to 70°C, and then 0.33 g of iodopropane was slowly added. The reaction was heated to reflux for 10 h, and the heating and reflux were stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-m8-n0-(CH2)2CH3).

[0052] Comparative Example 1

[0053] The difference from Example 1 is that the concrete foam stabilizer (GO-m4-n2) is not quaternary ammonium salt cationized.

[0054] 1 g of graphene oxide (OH density is 0.02 mol / g) was dispersed in 50 g of methanol, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.04 g of sodium methoxide, heated to 140 ° C, and slowly introduced with 4.64 g of propylene oxide. After reacting for 2 h, the temperature was lowered to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m4) with a hydrophobic segment.

[0055] 1 g of intermediate A (GO-m4) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, 0.05 g of DMAP / DCC was added, the temperature was raised to 80 ° C, and then 0.36 g of N, N-dimethylglycine was slowly added. The mixture was heated to reflux and reacted for 4 hours. The temperature was then lowered to 50 ° C, and the solvent was distilled off to obtain a crude product that was filtered, washed with ethanol, and dried to obtain an intermediate B (GO-m4-n2) with strong hydrophobicity.

[0056] Comparative Example 2

[0057] The difference from Example 1 is that the concrete foam stabilizer (GO-n2-b0) without modified propylene oxide hydrophobic chain

[0058] 1 g of graphene oxide (OH density is 0.02 mol / g) was dispersed in 50 g of methanol, ultrasonically dispersed for 1 h, and put into a reactor in a reflux water separator, 0.05 g of DMAP / DCC was added, the temperature was raised to 80 ° C, and then 2.06 g of N, N-dimethylglycine was slowly added. The mixture was heated to reflux and reacted for 4 h, then cooled to 50 ° C, and the solvent was distilled off to obtain a crude product that was filtered, washed with ethanol, and dried to obtain an intermediate B (GO-n2) with strong hydrophobicity.

[0059] 1 g of intermediate B (GO-n2) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, heated to 80°C, and then 0.52 g of ethyl iodide was slowly added. The reaction was heated under reflux for 6 h, and the heating and reflux were stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-n2-CH2CH3).

[0060] Comparative Example 3

[0061] The difference from Example 1 is that the concrete foam stabilizer (GO-m4) of unmodified N,N dialkyl fatty acid

[0062] 1 g of graphene oxide (OH density is 0.02 mol / g) was dispersed in 50 g of methanol, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.04 g of sodium methoxide, heated to 140 ° C, and slowly introduced with 4.64 g of propylene oxide. After reacting for 2 h, the temperature was lowered to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m4) with a hydrophobic segment.

[0063] 1 g of intermediate A (GO-m4) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, heated to 80°C, and then 0.52 g of ethyl iodide was slowly added. The reaction was heated under reflux for 6 h, and the heating and reflux were stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-m4).

[0064] The intermediates of unmodified N,N-dialkyl fatty acids cannot react with halogenated alkanes, that is, only the propylene oxide hydrophobic chains are modified on the surface of graphene oxide.

[0065] Comparative Example 4

[0066] The difference from Example 1 is that only graphene oxide (GO) is included.

[0067] Comparative Example 5

[0068] The difference from Example 1 is that iodine pentane is used as a halogenated alkane to quaternize the material with a cationized concrete foam stabilizer (GO-m4-n2-(CH2)4CH3)

[0069] 1 g of graphene oxide (OH density is 0.02 mol / g) was dispersed in 50 g of methanol, ultrasonically dispersed for 1 h, put into a reactor, introduced with nitrogen, added with 0.04 g of sodium methoxide, heated to 140 ° C, and slowly introduced with 4.64 g of propylene oxide. After reacting for 2 h, the temperature was lowered to below 50 ° C, filtered, washed with ethanol, and dried to obtain intermediate A (GO-m4) with a hydrophobic segment.

[0070] 1 g of intermediate A (GO-m4) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, 0.05 g of DMAP / DCC was added, the temperature was raised to 80 ° C, and then 0.36 g of N, N-dimethylglycine was slowly added. The mixture was heated to reflux and reacted for 4 hours. The temperature was then lowered to 50 ° C, and the solvent was distilled off to obtain a crude product that was filtered, washed with ethanol, and dried to obtain an intermediate B (GO-m4-n2) with strong hydrophobicity.

[0071] 1 g of the intermediate (GO-m4-n2) was dissolved in 50 g of methanol, put into a reactor with a reflux water separator, heated to 80°C, and then 0.66 g of iodine pentane was slowly added. The mixture was heated to reflux for 6 h, and the heating and reflux were stopped. The temperature was lowered to 50°C, and the solvent was distilled off. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain the concrete foam stabilizer C (GO-m4-n2-(CH2)4CH3).

[0072] The preparation information of the above examples and comparative examples is shown in Table 1 below:

[0073] Table 1 Molecular structure information of materials prepared in Examples and Comparative Examples

[0074] OH density / mol / g m n R1 R2 Example 1 0.02 4 2 <![CDATA[CH3]]> <![CDATA[CH2CH3]]> Example 2 0.03 2 4 <![CDATA[CH3]]> <![CDATA[(CH2)2CH3]]> Example 3 0.04 10 5 <![CDATA[CH2CH3]]> <![CDATA[(CH2)2CH3]]> Example 4 0.01 2 0 <![CDATA[CH3]]> <![CDATA[CH3]]> Example 5 0.025 8 0 <![CDATA[CH2CH3]]> <![CDATA[(CH2)2CH3]]> Comparative Example 1 0.02 4 2 <![CDATA[CH3]]> - Comparative Example 2 0.02 - 2 <![CDATA[CH3]]> <![CDATA[CH3]]> Comparative Example 3 0.02 4 - - - Comparative Example 4 0.02 - - - - Comparative Example 5 0.02 4 2 <![CDATA[CH3]]> <![CDATA[(CH2)4CH3]]>

[0075] Test Example 1: Performance Test

[0076] The test was carried out in accordance with the relevant provisions of GB8076-2008 "Concrete Admixtures", and the foam stabilizer obtained in the synthesis example was used to test the air content and strength of the concrete, and the bubble structure and parameters of the corresponding concrete test block were measured using a hardening pore structure analyzer. The compressive strength test was carried out in accordance with the compressive strength test in GBT50081-2002 "Test Methods for Mechanical Properties of Ordinary Concrete" to test the compressive strength of the quaternary ammonium salt-containing cationic graphene oxide material. The test block was a 15cm×15cm×15cm cube, and the concrete test block was placed in a standard curing room for 28 days before the test.

[0077] The concrete mix ratio used is shown in Table 2:

[0078] Table 2

[0079] cement Sand Dashi Xiaoshi water Polycarboxylate water reducer / rubber 3.30kg 7.29kg 7.14kg 4.76kg 1.25kg 0.15wt%

[0080] The cement used is Jiangnan Onoda P.II 52.5 cement, the sand is medium sand with fineness modulus Mx=2.7, and the coarse aggregate is 5-20mm continuous graded crushed stone. The polycarboxylate water reducer and anion air entraining agent used are provided by Jiangsu Subote New Materials Co., Ltd.

[0081] The specific test results are shown in Table 3 below:

[0082] Table 3

[0083]

[0084] From the test data of the initial concrete air content and the air content after 1h in Table 3, it can be seen that the concrete foam stabilizer based on the quaternary ammonium salt cationic graphene oxide material of the present invention has basically no air entraining effect initially, but has an excellent foam stabilizing effect when used in combination with anionic air entraining agent. The initial air content of the concrete mixed with the embodiment is basically the same as the initial air content of the concrete mixed with only the air entraining agent, but the air content after 1h is higher than the air content of the concrete mixed with only the air entraining agent, and the air content loss is reduced.

[0085] It can be seen from the data of Examples 1 to 5 that the foam stabilizing effect of Example 1 is the best, indicating that the quaternary ammonium salt cationized graphene oxide material with a suitable propylene oxide hydrophobic segment and an alkyl chain with a suitable carbon number has the best foam stabilizing effect; by comparing Examples 1 and 3, it can be seen that the foam stabilizing effect of the concrete foam stabilizer with a large number of propylene oxides and a long alkyl chain will be relatively worse, because a large number of propylene oxides and a long carbon chain length will cause molecular entanglement, weakening the electrostatic attraction between it and the anionic air entraining agent, affecting the foam stabilizing effect; by comparing Examples 1 and 4, it can be seen that the foam stabilizing effect of the concrete foam stabilizer with a small number of propylene oxides and a short alkyl chain will also be relatively worse, because the hydrophobicity of the small number of propylene oxides and the short carbon chain length will be relatively poor, and even become a hydrophilic material, and the molecules of this material will not be distributed at the gas-liquid interface of the bubble, but will be free in the concrete slurry, losing the original foam stabilizing effect.

[0086] By comparing the data of Example 1 and Comparative Example 1, it can be seen that quaternary ammonium salt cationization is an important technical means of the material of the present invention. Comparative Example 1 is a modified material that only has hydrophobicity but no hydrophilic group. When it is used in combination with anion air entrainment, the material molecules cannot be arranged at the gas-liquid interface of the bubble to form an electrostatic adsorption effect with the air entraining agent, and thus there is no good foam stabilizing effect; similarly, by comparing the data of Example 1 and Comparative Examples 2, 3, 4, and 5, it can be seen that if the material is not modified with hydrophobic ethylene oxide and alkyl carbon chain, its foam stabilizing effect will deteriorate or even disappear; in addition, the foam stabilizing effect of Comparative Example 5 in which the material is cationically modified with iodine pentane is also poor because the alkyl group of iodine pentane is longer, and the steric hindrance is large, resulting in the cationization reaction process not being as strong as the reaction of the shorter alkyl chain, the material preparation is not thorough, and the longer alkyl chain will also cause the entanglement of the material molecules to affect the performance of foam stabilization. In summary, the quaternary ammonium salt cation-modified graphene oxide material proposed in the present invention needs to have a surface with positive charge, a suitable propylene oxide hydrophobic segment, and an alkyl chain with a suitable carbon number to have an excellent foam stabilizing effect.

[0087] By comparing the data of the hardened average pore diameter of concrete in Table 3, it can be seen that the hardened average pore diameter of concrete mixed with Examples 1 to 5 is smaller than that of the blank group mixed with only air entraining agent, which further illustrates that the concrete foam stabilizer proposed in the present invention is conducive to the role of anionic air entraining agent, and forms a double-layer film of nanomaterial-air entraining agent on the surface of the bubble liquid film between the concrete and the air entraining agent, thereby increasing the thickness of the bubble film, making the introduced bubbles stable and unbroken, and the pores after hardening are smaller, which is conducive to the stability of the air content of the concrete.

[0088] By comparing the strength data in Table 3, it can be seen that the quaternary ammonium salt cation-modified graphene oxide material proposed in the present invention has a significant improvement effect on the compressive strength of concrete, and has a high compressive strength even when the air content is high. This is because the graphene oxide used in the material of the present invention has excellent mechanical properties and high hardness. Therefore, concrete mixed with the material provided by the present invention can solve the problem of concrete strength loss caused by increased air content.

[0089] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A concrete foam stabilizer based on quaternary ammonium salt cationized graphene oxide material, characterized in that: The concrete foam stabilizer is obtained by first hydrophobically modifying the hydroxyl groups on the surface of graphene oxide with propylene oxide to obtain an intermediate A, and then using N,N dialkyl fatty acid to perform a quaternary ammonium salt cationization reaction on the intermediate A. The mass ratio of graphene oxide to propylene oxide is 1:(1-24); The mass ratio of the intermediate A to N,N dialkyl fatty acid is 1:(0.1-1.2); The structural formula of the concrete foam stabilizer is shown in the following formula (1): Wherein, m=an integer from 2 to 10; n=an integer from 0 to 5; R1 is CH3 or CH3CH2; R2 is CH3, CH3CH2 or CH3(CH2)2.

2. A concrete foam stabilizer according to claim 1, characterized in that: The N,N dialkyl fatty acid is any one of N,N dimethylaminoformic acid, N,N dimethylglycine, N,N dimethylalanine, 4-N,N dimethylaminobutyric acid, diethylaminoformic acid, diethylaminoacetic acid, diethylaminopropionic acid, diethylaminobutyric acid, and diethylaminovaleric acid.

3. A concrete foam stabilizer according to claim 1, characterized in that: The density of hydroxyl groups in the graphene oxide is 0.01 to 0.04 mol / g.

4. A method for preparing a concrete foam stabilizer based on a quaternary ammonium salt cationized graphene oxide material according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: (1) dispersing graphene oxide in an organic solvent, adding a catalyst I under nitrogen protection, slowly introducing propylene oxide, cooling, filtering, washing and drying after the reaction is completed, and obtaining an intermediate A with a hydrophobic segment; (2) dissolving the intermediate A in an organic solvent, adding a catalyst II, and then slowly adding a nitrogen-containing polycarboxylic acid, heating and refluxing, and after the reaction is completed, distilling off the solvent, filtering, washing and drying to obtain an intermediate B with strong hydrophobicity; and (3) dissolving the intermediate B in an organic solvent, slowly adding a halogenated alkane, and after the reaction is completed, distilling off the solvent, filtering, washing and drying to obtain a concrete foam stabilizer.

5. The preparation method according to claim 4, characterized in that: During the steps (1), (2), and (3), the mass percentage concentration of graphene oxide, intermediate A, and intermediate B after being dissolved in an organic solvent is 1% to 50%.

6. The preparation method according to claim 4, characterized in that: In the step (1), the catalyst I is any one of sodium methoxide, sodium hydroxide, potassium hydroxide and sodium ethoxide; the amount of the catalyst I is 3-5% of the mass of the graphene oxide.

7. The preparation method according to claim 4, characterized in that: In the step (2), the catalyst II is any one of sodium p-toluenesulfonate, 4-dimethylaminopyridine / N,N'-dicyclohexylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride / N-hydroxysuccinimide; the amount of the catalyst II is 3-10% of the mass of the intermediate A.

8. The preparation method according to claim 4, characterized in that: In the step (3), the halogenated alkane is any one of methyl iodide, ethyl iodide, propyl iodide, methyl bromide, ethyl bromide and propyl bromide; and the amount of the halogenated alkane used is 0.03 to 0.9 times the mass of the intermediate B.

9. The preparation method according to claim 4, characterized in that: The reaction temperature of step (1) is 130°C to 160°C, and the reaction time is 1 to 3 hours; the reaction temperature of step (2) is 80 to 130°C, and the reaction time is 3 to 5 hours; the reaction temperature of step (3) is 70 to 110°C, and the reaction time is 4 to 10 hours.

10. An application of a concrete foam stabilizer based on quaternary ammonium salt cationic graphene oxide material, characterized in that: The foam stabilizer is used in combination with an anionic air entraining agent; the mass ratio of the foam stabilizer to the anionic air entraining agent is (0.01-0.5):1; the total amount of the foam stabilizer and the anionic air entraining agent is (0.05-1.0) ten thousandths of the mass of the total cementitious material; the foam stabilizer is the foam stabilizer described in any one of claims 1-3 or the foam stabilizer obtained by the preparation method described in any one of claims 4-9.

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