High-foam-stability concrete air entraining agent with multi-substructure and preparation method of high-foam-stability concrete air entraining agent

Abstract

The invention discloses a high-foam-stability concrete air entraining agent with a multi-substructure and a preparation method of the high-foam-stability concrete air entraining agent. The air entraining agent comprises a polyamine main chain, a hydrophobic chain mounted on the polyamine main chain and a phosphonate anion functional group grafted on the polyamine main chain. The molecular structure of the air entraining agent provided by the invention has the advantages of multi-type, high surface activity, lower solid doping amount compared with the conventional air entraining agent, uniform and fine bubbles can be generated when the air entraining agent is added into premixed concrete, the stability of the bubbles in time is excellent, the workability of the premixed concrete can be greatly improved, and the bleeding rate and the slurry bleeding rate are obviously reduced; the branched chains are multi-sub-chains, good air entraining and foam stabilizing effects are achieved, the main chain has a good reinforcing effect, concrete strength reduction caused by increase of the air content is made up, and the air entraining and foam stabilizing performance of the whole system is kept excellent; phosphonic acid groups in molecules of the air entraining agent are insensitive to components of concrete and mineral admixtures and have relatively weak adsorption capacity to clay, so that the air entraining agent has relatively good retarding and slump retaining properties.

Description

Technical Field

[0001] This invention relates to concrete admixtures, specifically to a highly stable foaming concrete air-entraining agent with a multi-substructure and its preparation method. Background Technology

[0002] Concrete is a widely used building material formed by mixing materials in a certain proportion. With the development of the domestic construction industry, the functionality of concrete has been put forward with very high requirements. Aerated concrete is a new type of concrete that is made by fully mixing foam and cement paste and then pumping it for on-site pouring or molding. It has the advantages of being lightweight, heat-insulating, fire-resistant, sound-insulating, and frost-resistant.

[0003] Aerated concrete plays a vital role throughout its entire life cycle. In the ready-mixed concrete stage, a certain amount of air bubbles can improve the concrete's fluidity, encapsulation, and softness, reducing problems such as spalling, bleeding, grout leakage, or aggregate loss. In other words, air bubbles are crucial and indispensable in ensuring the workability of concrete. During the hardening stage, the migration, coalescence, aggregation, and overflow of air bubbles can lead to problems affecting the appearance of hardened concrete, such as pitting and honeycombing. However, the micro- and nano-sized air bubbles remaining in the concrete system are equally important, playing a crucial role in the concrete's air permeability, water permeability, shrinkage, and freeze-thaw resistance. Therefore, air bubbles play a significant role throughout the entire life cycle of concrete, exhibiting a dual nature. Thus, controlling air bubbles in concrete is a major research topic, and air-entraining agents are an important means to address this issue.

[0004] Concrete air-entraining agents generally possess an amphiphilic molecular structure with molecular weights ranging from several thousand to ten thousand. Their main function is to introduce a large number of fine, uniform, and stable air bubbles during concrete mixing, thereby regulating the performance of the pre-mixed stage and the mechanical properties during the hardening stage. In practical applications, the dosage of air-entraining agent in concrete only needs to be a few thousandths to a few ten-thousandths of the cement content to meet the usage requirements. Currently commonly used concrete air-entraining agents include: rosin resins, alkyl and alkyl aromatic sulfonates, fatty alcohol sulfonates, saponins, protein salts, petroleum sulfonates, etc. From a chemical structure perspective, the above-mentioned air-entraining agents are all traditional single-chain surfactants, i.e., amphiphilic molecules with a hydrophilic group at one end and a hydrophobic group at the other end.

[0005] In summary, current technical solutions mainly involve the mixing and simple chemical modification of existing amphiphilic surfactant molecules (such as the air-entraining agents disclosed in CN116924719A, CN110104986A, and CN117049814A). However, with the changes in concrete construction and usage scenarios such as low-grade manufactured sand, various types of mineral admixtures, and harsh construction environments, using only mixing methods is somewhat simplistic and suffers from poor air-entraining and foam-stabilizing properties. Summary of the Invention

[0006] To address the issues of single-chain molecular structure and poor bubble stability of air-entraining agents, this invention provides a highly stable concrete air-entraining agent with a multi-substrate structure and its preparation method. This air-entraining agent adopts a multi-substrate structure, which not only has high surface activity but also a lower folded solids content than conventional air-entraining agents. It can generate uniform and fine bubbles, and the bubbles exhibit excellent stability over time.

[0007] To achieve the above objectives, the present invention provides a highly stable foaming concrete air-entraining agent with a multi-substrate structure, comprising a polyamine backbone, a hydrophobic chain mounted on the polyamine backbone, and a phosphonate anionic functional group grafted onto the polyamine backbone, the structural formula of which is as follows:

[0008] in: R1 is an alkyl group containing C1~C14 aliphatic straight chains, branches, or cyclic chains, or an alkyl aryl group containing C0~C4 aliphatic straight chains or branches; R2 is methyl, ethyl, or butyl; m is 4~40, n is 1~10, x is 2~10, and y is 2~10.

[0009] Preferably, the ratio of the hydrophobic chain, the polyamine backbone, and the phosphonate anionic functional group is (2~10):1:(2~10).

[0010] Preferably, the hydrophobic chain has a molecular weight of 200-2000 and a hydrophilic-lipophilic balance (HLB) of 10-20. Controlling the HLB of the hydrophobic segment is particularly crucial; an HLB of 10-20 indicates that the hydrophobic segment possesses gas-entraining capabilities.

[0011] Preferably, the polyamine molecule contains an ethylenediamine chain segment.

[0012] Preferably, the phosphonic acid group is linked to the polyamine molecule via a methylene group, and the number of phosphonate groups is two or more, specifically determined by the NH content of the main chain and the amount of grafted hydrophobic chains occupied.

[0013] The second aspect of this invention provides a method for preparing the above-mentioned high-stability foaming concrete air-entraining agent with a multi-substrate structure. This method involves a ring-opening polymerization reaction between a corresponding monohydric alcohol and an epoxy compound, followed by a reaction with a halogenating agent to obtain an intermediate halogenated polyether. The halogenated polyether then undergoes a nucleophilic substitution reaction with a polyamine backbone, followed by a one-step Mannich reaction in an aqueous system to obtain the final product. Specifically, the method includes the following steps: S1. After mixing the initiator and catalyst, under anaerobic conditions of 100~160℃ and 0.1~0.4Mpa, the epoxy compound is slowly introduced to react until the feeding is finished, and then cured for 0.5~1h to obtain the polyether intermediate. S2. At 65~75℃, a halogenated reagent is added dropwise to the polyether intermediate. After the addition is completed, the temperature is maintained for 2~3 hours to obtain the intermediate halogenated polyether. The hydrogen halide tail gas from the condensation reaction of the polyether intermediate and the halogenated reagent is degassed under vacuum and absorbed by conventional liquid alkali (5~30% sodium hydroxide or potassium hydroxide aqueous solution). The absorption equipment is a conventional absorption tank with submerged gas inlet or a spray tower for industrial tail gas. Single-stage, two-stage or multi-stage absorption can be used. S3. Add halogenated polyether and polyamine molecules according to a molar ratio of NH functional groups of 1:2 and react at 95~105℃ for 2~4h to obtain the amination polyether intermediate. S4. The amination polyether intermediate, aldehyde and phosphorous acid are mixed evenly and reacted at 100~120℃ for 2~12h under the action of a catalyst to obtain a high-stability foaming concrete air-entraining agent with a multi-particle structure.

[0014] Preferably, when R1 is an alkyl group containing a C1-C14 aliphatic straight chain, branched chain, or cyclic chain, its initiator is a monohydric alcohol containing the corresponding chain structure, selected from methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 1-pentanol, isoamyl alcohol, 1-hexanol, isohexanol, cyclopentanol, cyclohexanol, C8-C10 fatty alcohols, C10-C12 fatty alcohols, and C12-C14 fatty alcohols; When R1 is a C0~C4 aliphatic straight-chain or branched alkyl aryl group, its initiator is a monohydric phenol containing the corresponding chain structure, selected from phenol, p-methylphenol, p-ethylphenol, p-propylphenol, p-isopropylphenol, p-butylphenol, p-isobutylphenol, and p-tert-butylphenol. The epoxy compound is selected from one or more of ethylene oxide, propylene oxide, butane oxide, and pentane oxide; The catalyst is potassium hydroxide, sodium methoxide, sodium metal, or sodium hydride; The molar ratio of the initiator, catalyst and epoxide is 1:(0.04~0.06):(11~24).

[0015] Preferably, in step S2, the halogenated reagent is selected from one or more of thionyl chloride, phosphorus trichloride, and phosphorus pentachloride; the molar ratio of the polyether intermediate to the halogenated reagent is 1:(1.02~1.1).

[0016] Preferably, in step S3, the polyamine molecule is selected from one or more of the monomers diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethylenepolyamine.

[0017] Preferably, in step S4, the catalyst is selected from concentrated sulfuric acid, p-toluenesulfonic acid, βOne of the following: naphthalenesulfonic acid, trifluoromethanesulfonic acid, strong acidic cationic resin NKC-9, and perfluorosulfonic acid resin Nafion SAC, is used in an amount of 1.0% to 10.0% of the molar amount of the phosphonic acid reagent, i.e., phosphorous acid; The amount of aldehyde used is 1.0 to 2.0 times the molar amount of NH functional group; the amount of phosphorous acid used is 1.0 to 2.0 times the molar amount of NH functional group. The amount of water added as solvent is 30% to 50% of the sum of the molecular weights of the haloether and the polyamine.

[0018] When used, its dosage (converted to solid dosage) is 0.001%~0.05% of the total cementitious material mass. When the dosage is less than 0.001%, its dispersibility is poor and cannot meet the engineering requirements. When the dosage is greater than 0.05%, it cannot resolve the contradiction between high air content and high freeze-thaw resistance / high strength in increasingly complex concrete raw material systems such as poorly graded / high powder / high mud content manufactured sand, high carbon content mineral admixtures, and various types of cement with varying compositions, as well as in special scenarios such as hydropower dams, marine engineering, high altitude, low air pressure, and large temperature differences.

[0019] Through the above technical solution, the present invention achieves the following beneficial effects: The air-entraining agent of this invention has a multi-particle molecular structure, high surface activity, and a lower folded-solid content than conventional air-entraining agents. When added to ready-mixed concrete, it can generate uniform and fine bubbles with excellent stability over time, which can greatly improve the workability of ready-mixed concrete and significantly reduce bleeding rate and slurry rate. The multi-particle branched chain brings better air-entraining and foam-stabilizing effects, while the main chain has a good reinforcing effect, compensating for the decrease in concrete strength caused by increased air content, and maintaining excellent air-entraining and foam-stabilizing performance of the overall system. The phosphonic acid groups in the air-entraining agent molecule are not sensitive to concrete and mineral admixture components and have weak adsorption capacity for clay, thus the air-entraining agent has good retarding and slump-preserving properties. It can have a synergistic effect with other air-entraining agents, has good compatibility, can be used and stored stably, and the raw materials are readily available. The parameters are mild, which is conducive to industrialization. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in detail below with reference to examples. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0021] All materials used in this invention are commercially available commodities. The raw materials used in the synthesis were purchased from Nanjing Wanqing Reagent Co., Ltd., the organic solvents (chemically pure) were purchased from Sinopharm Chemical Reagent Co., Ltd., and the polycarboxylate superplasticizer was produced by Jiangsu Subote New Material Co., Ltd.

[0022] Example 1 Methods for preparing highly stable foaming concrete air-entraining agents with multi-substrate structures include: S1. In a dry reactor, add 1 mol of methanol as the initiator and 0.04 mol of sodium methoxide as the catalyst. After purging with nitrogen, heat to 100ºC and control the pressure at 0.4 MPa. Slowly introduce 10 mol of propylene oxide. After the feeding is completed, allow it to mature for 0.5 h. Continue to introduce 6 mol of ethylene oxide. After the feeding is completed, allow it to mature for 0.5 h. Evacuate the gas and cool to room temperature. Neutralize with acetic acid to a pH of about 7.0 to obtain a polyether intermediate. S2. Add 1 mol of polyether intermediate to the reaction flask, stir, heat to 65°C, slowly add 1.1 mol of thionyl chloride, control the reaction temperature not to exceed 75°C, until the addition is complete, and then keep warm for 2 hours. The exhaust gas is passed into the alkaline absorption bottle (secondary). Turn on the vacuum system after the absorption bottle until the reaction is complete, stop the vacuum, balance the pressure of the reaction bottle, and discharge the material to obtain the intermediate chlorinated polyether. S3. Add 1 mol of chlorinated polyether, 0.5 mol of diethylenetriamine, and 30% of the total mass of chlorinated polyether and diethylenetriamine to a four-necked flask equipped with a reflux condenser. Stir and reflux at 95°C for 2 hours under constant temperature oil bath conditions. Then cool down and discharge the material to obtain the amination polyether intermediate. S4. In a four-necked flask equipped with a reflux condenser, add 1 mol of amination polyether intermediate, 0.6 mol of 37.5% formaldehyde solution, 0.6 mol of phosphorous acid, and 0.024 mol of concentrated sulfuric acid in sequence. Under constant temperature heating in an oil bath, stir and heat to 105℃ for reflux reaction for 6 hours. Then cool down, adjust the solid content of the material with water to 60%, and discharge the material to obtain a high-stability foaming concrete air-entraining agent with a multi-particle structure.

[0023] Example 2 Methods for preparing highly stable foaming concrete air-entraining agents with multi-substrate structures include: S1. In a dry reactor, add 1 mol of 1-butanol as the initiator and 0.04 mol of sodium methoxide as the catalyst. After purging with nitrogen, heat to 160ºC and control the pressure at 0.1 MPa. Slowly introduce 4 mol of propylene oxide. After the feeding is completed, allow it to mature for 0.5 h. Continue to introduce 8 mol of ethylene oxide. After the feeding is completed, allow it to mature for 0.5 h. Evacuate the gas and cool to room temperature. Neutralize with acetic acid to a pH of about 7.0 to obtain a polyether intermediate. S2. Add 1 mol of polyether intermediate to the reaction flask, stir, heat to 65°C, slowly add 1.05 mol of thionyl chloride, control the reaction temperature not to exceed 75°C, until the addition is complete, then keep warm for 2 hours. The exhaust gas is passed into the alkaline absorption bottle (secondary). Turn on the vacuum system after the absorption bottle until the reaction is complete, then stop the vacuum, balance the pressure of the reaction bottle, and discharge the material to obtain the intermediate chlorinated polyether. S3. Add 1 mol of chlorinated polyether, 0.3 mol of triethylenetetramine, and water (50% of the total mass of chlorinated polyether and triethylenetetramine) to a four-necked flask equipped with a reflux condenser. Stir and reflux at 95°C for 2 hours under constant temperature oil bath conditions. Then cool down and discharge the material to obtain the amination polyether intermediate. S4. Add 1 mol of amination polyether intermediate, 0.3 mol of 37.5% formaldehyde solution, 0.3 mol of phosphorous acid, and 0.015 mol of p-toluenesulfonic acid to a four-necked flask equipped with a reflux condenser in sequence. Stir and reflux at 100°C for 12 hours under constant temperature oil bath conditions. Then cool down, adjust the solid content of the material with water to 60%, and discharge the material to obtain a high-stability foaming concrete air-entraining agent with a multi-particle structure.

[0024] Example 3 Methods for preparing highly stable foaming concrete air-entraining agents with multi-substrate structures include: S1. In a dry reactor, add 1 mol of initiator C10-C12 fatty alcohol (CAS No.: 68154-97-2) and 0.06 mol of catalyst sodium methoxide. After purging with nitrogen, heat to 120ºC, control the pressure at 0.2MPa, and slowly introduce 1 mol of propylene oxide. After the feed is completed, allow it to mature for 0.5h. Then, continue to introduce 10 mol of ethylene oxide. After the feed is completed, allow it to mature for 0.5h. Evacuate the gas, cool to room temperature, and neutralize with acetic acid to a pH of about 7.0 to obtain a polyether intermediate. S2. Add 1 mol of polyether intermediate to the reaction flask, stir, heat to 65°C, slowly add 1.06 mol of thionyl chloride, control the reaction temperature not to exceed 75°C, until the addition is complete, and then keep warm for 3 hours. The exhaust gas is passed into the alkaline absorption bottle (secondary). Turn on the vacuum system after the absorption bottle until the reaction is complete, stop the vacuum, balance the pressure of the reaction bottle, and discharge the material to obtain the intermediate chlorinated polyether. S3. Add 1 mol of chlorinated polyether, 0.2 mol of tetraethylenepentamine, and water accounting for 40% of the total mass of chlorinated polyether and tetraethylenepentamine to a four-necked flask equipped with a reflux condenser. Stir and reflux at 100°C for 3 hours under constant temperature oil bath conditions. Then cool down and discharge the material to obtain the amination polyether intermediate. S4. Add 1 mol of amination polyether intermediate, 0.3 mol of 37.5% formaldehyde solution, and 0.3 mol of phosphorous acid sequentially to a four-necked flask equipped with a reflux condenser. β 0.024 mol of naphthalenesulfonic acid was stirred in a constant-temperature oil bath and refluxed at 110°C for 4 hours. The mixture was then cooled, and the solid content of the material was adjusted to 60% with water before being discharged to obtain a highly stable foaming concrete air-entraining agent with a multi-particle structure.

[0025] Example 4 Methods for preparing highly stable foaming concrete air-entraining agents with multi-substrate structures include: S1. In a dry reactor, add 1 mol of cyclohexanol as the initiator and 0.05 mol of sodium methoxide as the catalyst. After purging with nitrogen, heat to 160ºC and control the pressure at 0.4 MPa. Slowly introduce 6 mol of propylene oxide. After the feed is completed, allow it to mature for 0.5 h. Then, continue to introduce 14 mol of ethylene oxide. After the feed is completed, allow it to mature for 0.5 h. Evacuate the gas and cool to room temperature. Neutralize with acetic acid to a pH of about 7.0 to obtain a polyether intermediate. S2. Add 1 mol of polyether intermediate to the reaction flask, stir, heat to 65°C, slowly add 1.04 mol of thionyl chloride, control the reaction temperature not to exceed 75°C, until the addition is complete, then keep warm for 3 hours. The exhaust gas is passed into the alkaline absorption bottle (secondary). Turn on the vacuum system after the absorption bottle until the reaction is complete, then stop the vacuum, balance the pressure of the reaction bottle, and discharge the material to obtain the intermediate chlorinated polyether. S3. Add 1 mol of chlorinated polyether, 0.1 mol of pentaethylenehexamine, and 30% of the total mass of chlorinated polyether and pentaethylenehexamine to a four-necked flask equipped with a reflux condenser. Stir and reflux at 100°C for 3 hours under constant temperature oil bath conditions. Then cool down and discharge the material to obtain the amination polyether intermediate. S4. In a four-necked flask equipped with a reflux condenser, add 1 mol of amination polyether intermediate, 0.2 mol of 37.5% formaldehyde solution, 0.2 mol of phosphorous acid, and 0.016 mol of trifluoromethanesulfonic acid in sequence. Under constant temperature heating in an oil bath, stir and reflux at 110°C for 4 hours. Then cool down, adjust the solid content of the material with water to 60%, and discharge the material to obtain a high-stability foaming concrete air-entraining agent with a multi-cell structure.

[0026] Example 5 Methods for preparing highly stable foaming concrete air-entraining agents with multi-substrate structures include: S1. In a dry reactor, add 1 mol of phenol as an initiator and 0.05 mol of sodium hydride as a catalyst. After purging with nitrogen, heat to 130ºC and control the pressure at 0.3 MPa. Slowly introduce 8 mol of butylene oxide. After the feeding is complete, allow it to mature for 0.5 h. Then, continue to introduce 10 mol of pentane oxide. After the feeding is complete, allow it to mature for 0.5 h. Evacuate the gas and cool to room temperature. Neutralize with acetic acid to a pH of about 7.0 to obtain a polyether intermediate. S2. Add 1 mol of polyether intermediate to the reaction flask, stir, heat to 65°C, slowly add 1.02 mol of phosphorus trichloride, control the reaction temperature not to exceed 75°C, until the addition is complete, and then keep warm for 3 hours. The tail gas is passed into the alkaline absorption bottle (secondary). Turn on the vacuum system after the absorption bottle until the reaction is complete, stop the vacuum, balance the pressure of the reaction bottle, and discharge the material to obtain the intermediate chlorinated polyether. S3. Add 1 mol of chlorinated polyether, 0.05 mol of polyethylene polyamine, and water (30% of the total mass of chlorinated polyether and polyethylene polyamine) to a four-necked flask equipped with a reflux condenser. Stir and reflux at 105°C for 2 hours under constant temperature oil bath conditions. Then cool down and discharge the material to obtain the amination polyether intermediate. S4. In a four-necked flask equipped with a reflux condenser, add 1 mol of amination polyether intermediate, 0.1 mol of 37.5% formaldehyde solution, 0.1 mol of phosphorous acid, and 0.001 mol of strong acid cationic resin NKC-9 in sequence. Under constant temperature heating oil bath conditions, stir and heat to 115℃ for reflux reaction for 6 hours. Then cool down, adjust the solid content of the material with water to 60%, and discharge the material to obtain a high-stability foaming concrete air-entraining agent with a multi-particle structure.

[0027] Example 6 Methods for preparing highly stable foaming concrete air-entraining agents with multi-substrate structures include: S1. In a dry reactor, add 1 mol of p-tert-butylphenol as the initiator and 0.04 mol of sodium hydride as the catalyst. After purging with nitrogen, heat to 150ºC and control the pressure at 0.1 MPa. Slowly introduce 4 mol of epoxide. After the feeding is completed, ripen for 0.5 h, evacuate the gas, cool to room temperature, and neutralize with acetic acid to a pH of about 7.0 to obtain a polyether intermediate. S2. Add 1 mol of polyether intermediate to the reaction flask, stir, heat to 65°C, slowly add 1.04 mol of phosphorus pentachloride, control the reaction temperature not to exceed 75°C, until the addition is complete, then keep warm for 3 hours. The exhaust gas is passed into the alkaline absorption bottle (secondary). Turn on the vacuum system after the absorption bottle until the reaction is complete, then stop the vacuum, balance the pressure of the reaction bottle, and discharge the material to obtain the intermediate chlorinated polyether. S3. Add 1 mol of chlorinated polyether, 0.05 mol of polyethylene polyamine, and 30% of the total mass of chlorinated polyether and polyethylene polyamine to a four-necked flask equipped with a reflux condenser. Stir and reflux at 95°C for 4 hours under constant temperature oil bath conditions. Then cool down and discharge the material to obtain the amination polyether intermediate. S4. In a four-necked flask equipped with a reflux condenser, add 1 mol of amination polyether intermediate, 0.1 mol of 37.5% formaldehyde solution, 0.1 mol of phosphorous acid, and 0.01 mol of perfluorosulfonic acid resin Nafion SAC in sequence. Under constant temperature heating oil bath conditions, stir and heat to 120℃ for reflux reaction for 2 hours. Then cool down, adjust the solid content of the material with water to 60%, and discharge the material to obtain a high-stability foaming concrete air-entraining agent with a multi-cell structure.

[0028] Comparative Example 1 The other conditions are the same as in Example 1, except that only polyether intermediates that have not undergone chlorination are used.

[0029] Comparative Example 2 Commercially available sodium dodecyl polyoxyethylene ether sulfate (AES) air-entraining agent.

[0030] Performance testing The air content of concrete and the change in air content over 1 hour of the air-entraining agent of this invention were tested according to the method described in GB / T 8076-20086.5.4; The water leakage rate was tested according to the method described in GB / T 8076-2008 6.5.3; The compressive strength was tested according to the method described in GB / T 8076-2008 6.6.1; The distribution of air bubbles in fresh concrete was determined using the AVA3000 fresh concrete pore structure analyzer from German, Denmark.

[0031] This invention uses the mix proportions in Table 1 to test the air content of concrete and the change in air content over 1 hour, initial slump / flowability and 1-hour slump / flowability, bleeding rate, 28-day compressive strength, and air bubble distribution in fresh concrete.

[0032] Table 1 Concrete Mix Proportions

[0033] Table 2. Changes in air content and fluidity of concrete over time and hardening strength indices

[0034] Table 3. Air bubble distribution in freshly mixed concrete

[0035] Data in Tables 2 and 3 show that in natural sand, the air-entraining agent of this invention effectively improves workability, with a 1-hour bleeding rate of 0%, while the comparative example, due to its weak foam-stabilizing effect, has a bleeding rate exceeding 2%. Data on bubble time shows that the air-entraining agent of this invention has a strong foam-stabilizing effect in concrete systems, with an initial air content of 5%–6% and a 1-hour loss rate of less than 10%. In the initial fresh concrete, microbubbles with a diameter less than 50µm account for more than 65%, and the change over time is small; even after 1 hour, the proportion of microbubbles with a diameter less than 50µm in the fresh concrete can still reach more than 60%. Concrete incorporating the air-entraining agent of this invention exhibits a 28-day compressive strength greater than 98%, ensuring hardened strength. This is mainly because the branched chains of the air-entraining agent of this invention are multi-particle, which brings better air-entraining and foam-stabilizing effects, while the main chain has a good reinforcing effect, compensating for the decrease in concrete strength caused by increased air content without affecting the overall air-entraining and foam-stabilizing performance of the system.

[0036] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0037] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0038] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A highly stable foaming concrete air-entraining agent with a multi-substructure, characterized in that, It includes a polyamine backbone, a hydrophobic chain mounted on the polyamine backbone, and a phosphonate anionic functional group grafted onto the polyamine backbone, with the following structural formula: in: R1 is an alkyl group containing C1~C14 aliphatic straight chains, branches, or cyclic chains, or an alkyl aryl group containing C0~C4 aliphatic straight chains or branches; R2 is methyl, ethyl, or butyl; m is 4~40, n is 1~10, x is 2~10, and y is 2~10.

2. The high-stability foaming concrete air-entraining agent with a multi-substructure according to claim 1, characterized in that, The ratio of the hydrophobic chain, the polyamine backbone, and the phosphonate anionic functional group is (2~10):1:(2~10).

3. The high-stability foaming concrete air-entraining agent with a multi-substructure according to claim 1, characterized in that, The hydrophobic chain has a molecular weight of 200-2000 and a hydrophilic-lipophilic balance (HLB) of 10-20, while the air-entraining agent has a molecular weight of 1000-20000.

4. The high-stability foaming concrete air-entraining agent with a multi-substructure according to claim 1, characterized in that, The polyamine molecule contains ethylenediamine chain segments.

5. The high-stability foaming concrete air-entraining agent with a multi-substructure according to claim 1, characterized in that, The phosphonic acid group is linked to a polyamine molecule via a methylene group, and the number of phosphonate groups is two or more.

6. A method for preparing a high-stability foaming concrete air-entraining agent with a multi-substructure as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. After mixing the initiator and catalyst, under anaerobic conditions of 100~160℃ and 0.1~0.4Mpa, the epoxy compound is slowly introduced to react until the feeding is finished, and then cured for 0.5~1h to obtain the polyether intermediate. S2. At 65~75℃, add a halogenated reagent dropwise to the polyether intermediate, and keep warm for 2~3 hours after the addition is completed to obtain the intermediate halogenated polyether. S3. Add halogenated polyether and polyamine molecules according to a molar ratio of NH functional groups of 1:2 and react at 95~105℃ for 2~4h to obtain the amination polyether intermediate. S4. The amination polyether intermediate, aldehyde and phosphorous acid are mixed evenly in water and reacted at 100~120℃ for 2~12h under the action of a catalyst to obtain a highly stable foaming concrete air-entraining agent with a multi-particle structure.

7. The preparation method according to claim 6, characterized in that, When R1 is an alkyl group containing a C1~C14 aliphatic straight chain, branched chain, or cyclic chain, its initiator is a monohydric alcohol containing the corresponding chain structure, selected from methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 1-pentanol, isoamyl alcohol, 1-hexanol, isohexanol, cyclopentanol, cyclohexanol, C8-C10 fatty alcohol, C10-C12 fatty alcohol, and C12-C14 fatty alcohol; When R1 is a C0~C4 aliphatic straight-chain or branched alkyl aryl group, its initiator is a monohydric phenol containing the corresponding chain structure, selected from phenol, p-methylphenol, p-ethylphenol, p-propylphenol, p-isopropylphenol, p-butylphenol, p-isobutylphenol, and p-tert-butylphenol. The epoxy compound is selected from one or more of ethylene oxide, propylene oxide, butane oxide, and pentane oxide; The catalyst is potassium hydroxide, sodium methoxide, sodium metal, or sodium hydride; The molar ratio of the initiator, catalyst and epoxide is 1:(0.04~0.06):(11~24).

8. The method for preparing a high-stability foaming concrete air-entraining agent with a multi-substructure according to claim 6, characterized in that, In step S2, the halogenated reagent is selected from one or more of thionyl chloride, phosphorus trichloride, and phosphorus pentachloride; the molar ratio of the polyether intermediate to the halogenated reagent is 1:(1.02~1.1).

9. The method for preparing a high-stability foaming concrete air-entraining agent with a multi-substructure according to claim 6, characterized in that, In step S3, the polyamine molecule is selected from one or more of the monomers diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethylenepolyamine.

10. The method for preparing the high-stability foaming concrete air-entraining agent with a multi-substructure according to claim 6, characterized in that, In step S4, the catalyst is selected from concentrated sulfuric acid, p-toluenesulfonic acid, β The amount of one of the following is 1.0% to 10.0% of the molar amount of phosphorous acid: naphthalenesulfonic acid, trifluoromethanesulfonic acid, strong acid cationic resin NKC-9, and perfluorosulfonic acid resin Nafion SAC. The amount of aldehyde is 1.0 to 2.0 times the molar amount of NH functional group; the amount of phosphorous acid is 1.0 to 2.0 times the molar amount of NH functional group; and the amount of water is 30% to 50% of the sum of the molecular weights of the halogenated polyether and the polyamine.

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