High-slump-loss-resistant water reducing agent and preparation method thereof

Abstract

The invention relates to the technical field of building materials, and discloses a high slump loss resistant water reducing agent and a preparation method thereof, and the high slump loss resistant water reducing agent comprises 300 parts of isopentenyl polyoxyethylene ether macromonomer; 40-120 parts of unsaturated carboxylic acid and derivatives thereof; 5 to 25 parts of glucose; 5 to 40 parts of alkyl polyglucoside; 0.3 to 4.0 parts of an oxidizing agent; 0.3 to 4.0 parts of a reducing agent; 0.6 to 3.0 parts of a chain transfer agent; 5-12 parts of sodium hydroxide; water is used as a solvent for solution preparation and reaction. The isopentenyl polyoxyethylene ether macromonomer is combined with unsaturated carboxylic acid and derivatives thereof, a macromolecular chain is formed through a polymerization reaction, the dispersity and stability of the water reducing agent are improved, and compared with a single polymer system in the prior art, the water reducing agent has the advantages that the dispersion effect is improved, and meanwhile, the water reducing effect is improved. The slump retaining property of the water reducing agent in cement paste is obviously enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a high-slump-retention water-reducing agent and a preparation method thereof. Background Art

[0002] Concrete construction technology is one of the most important applied technologies in construction projects. The level of this technology directly determines the quality of the project. Currently, construction companies often use on-site concrete construction to facilitate the transportation and mixing of concrete. The long-term and long-distance transportation of mixed concrete will inevitably lead to an increase in the water-cement ratio and the thinning of the concrete, making it difficult to ensure the normal quality of the concrete. It is very likely to cause honeycombing and roughening of cast-in-place concrete components, greatly reducing the strength of the concrete structure and causing serious quality problems. Conventional concrete water reducers cannot solve the above problems. The development of a high-slump-retention polycarboxylate water reducer can effectively ensure the excellent working performance of concrete under normal proportions and long-term transportation.

[0003] In the concrete water-reducing agent industry, the addition of retarding components can ensure the performance of concrete during long transportation periods. However, the addition of retarding components can lead to an excessively long setting time for the concrete, resulting in extended demolding times, longer formwork life, and increased construction costs, hindering project progress. Maintaining the slump of concrete without retarding components is particularly important and has become a problem plaguing the concrete admixture industry. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a high-slump retention water reducer and a preparation method thereof, which solves the problem that the addition of concrete retarding components will lead to a long setting time of concrete, resulting in prolonged demoulding time, prolonged formwork use time and increased construction costs.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a high slump retention water reducer, comprising:

[0006] 300 parts of isopentenyl polyoxyethylene ether macromonomer;

[0007] 40-120 parts of unsaturated carboxylic acids and their derivatives;

[0008] 5-25 parts of glucose;

[0009] 5-40 parts of alkyl polyglycosides;

[0010] 0.3-4.0 parts of oxidizing agent;

[0011] 0.3-4.0 parts of reducing agent;

[0012] Chain transfer agent 0.6-3.0 parts;

[0013] 5-12 parts of sodium hydroxide;

[0014] Water is used as a solvent for solution preparation and reaction.

[0015] Furthermore, isopentyl polyoxyethylene ether macromonomer: This monomer acts as the basic unit of the molecular chain in the synthesis of the water reducer. It forms a high molecular structure with other components through polymerization reaction, effectively improving the functionality of the water reducer and ensuring its good dispersibility and high slump retention in the cement mixture.

[0016] Unsaturated carboxylic acids and their derivatives: Unsaturated carboxylic acids such as acrylic acid have good reactivity and can react with other monomers during the polymerization process to generate high molecular chains with negative charges, thereby improving the dispersibility of the water reducer.

[0017] Glucose: As a reducing agent and stabilizer, glucose helps to enhance the stability of the polymerization reaction, improve the uniform dispersion of the water reducer in cement, and further enhance the slump retention of the water reducer.

[0018] Alkyl polyglycoside: As a nonionic surfactant, alkyl polyglycoside can reduce surface tension in cement slurry, enhance water-reducing effect, improve the stability of water-reducing agent, and prevent cement particles from agglomerating.

[0019] Oxidants, reducing agents, chain transfer agents: These components control the rate, molecular weight and chain length of the polymerization reaction, and can effectively adjust the molecular structure and function of the water reducer to ensure its good water solubility and dispersibility.

[0020] Sodium hydroxide: As an alkali agent, sodium hydroxide is used to adjust the pH value after the reaction, so that the water reducer is in a stable environment and ensure the good performance of the final product.

[0021] Preferably, the unsaturated carboxylic acid and its derivatives are at least one of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, and maleic anhydride.

[0022] Furthermore, unsaturated carboxylic acids and their derivatives: Unsaturated carboxylic acids have double bonds or functional groups (such as hydroxyl groups). These functional groups can undergo cross-linking reactions with other components during the polymerization reaction to generate polymers with good water solubility and high dispersibility, which helps to improve the stability, slump retention and dispersibility of the water reducer in cement slurry.

[0023] Preferably, the alkyl polyglycoside is an alkyl polyglycoside produced by the reaction of C8-C16 fatty alcohol and glucose, and is selected from at least one of APG0810, APG0814, APG0816, and APG1214.

[0024] Furthermore, alkyl polyglycosides (APGs) are nonionic surfactants that effectively reduce the surface tension of cement particles, thereby enhancing the dispersibility of the water reducer. The length of the alkyl chain is directly related to the dispersibility. C8-C16 fatty alcohol chains provide a good hydrophilic-hydrophobic balance, helping to improve high slump retention and prevent cement particle agglomeration.

[0025] A method for preparing a high-slump-retention water-reducing agent comprises the following steps:

[0026] A pre-solution is prepared by dissolving 300 parts of isopentenyl polyoxyethylene ether macromonomer, 6-25 parts of glucose, and 0.3-4.0 parts of an oxidant in 350 parts of water to prepare solution A;

[0027] Dissolve 0.3-4.0 parts of reducing agent and 0.6-3.0 parts of chain transfer agent in 88 parts of water to prepare solution B;

[0028] Dissolve 40-120 parts of unsaturated acid and its derivatives in 40 parts of water to prepare solution C;

[0029] Dissolve 5-40 parts of alkyl polyglycoside in 50 parts of water to prepare solution D;

[0030] Polymerization reaction: Stir at 30-55°C and add solutions B, C, and D to solution A dropwise in sequence for 2.5-3 hours;

[0031] After the addition is completed, continue the reaction at a constant temperature of 30-55°C for 2 hours;

[0032] After the reaction, 5-12 parts of sodium hydroxide are added to the reaction solution to adjust the pH to 5-7 to obtain the high slump retention water reducer.

[0033] Next, the polymerization reaction: This step is the core of the entire synthesis process. An oxidizing agent and a reducing agent are combined to initiate a free radical polymerization reaction. Solutions B, C, and D are sequentially added dropwise to Solution A. This method allows for gradual control of the reaction rate and product molecular weight, ensuring the water reducer's dispersibility and slump retention.

[0034] Constant temperature reaction: Maintaining a constant temperature for the reaction time controls the stability of the molecular structure, avoiding side reactions or molecular chain breakage caused by excessively high temperatures, thereby ensuring the good performance of the water reducer.

[0035] Preferably, the oxidant is at least one of hydrogen peroxide, sodium persulfate, potassium persulfate, and ammonium persulfate.

[0036] Furthermore, oxidants are primarily used to initiate polymerization reactions. Hydrogen peroxide and persulfate-based oxidants decompose to generate free radicals, which then react with monomers to form polymer chains. The type and amount of oxidant directly influence the polymerization rate and the molecular weight of the product.

[0037] Preferably, the reducing agent is at least one of L-ascorbic acid, sodium bisulfite, ferrous sulfate, sodium sulfite, ferrous chloride, ferrous acetate, sodium hypophosphite, and sodium formaldehyde sulfenate.

[0038] Furthermore, reducing agents work synergistically with oxidants to help control the rate and selectivity of the polymerization reaction. The addition of reducing agents helps generate relatively stable free radicals, ensuring the smooth progress of the polymerization reaction.

[0039] Preferably, the chain transfer agent is at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, thioglycerol, and thiomalic acid.

[0040] Furthermore, chain transfer agent: Chain transfer agent terminates or transfers the growth of free radicals during the polymerization process by providing sulfur-containing functional groups, thereby controlling the molecular weight, helping to produce polymers with appropriate molecular weight and dispersibility, and improving the effectiveness of the water reducer.

[0041] Preferably, the order of adding the solutions B, C and D is B first, then C and then D, and the starting time of the three is the same.

[0042] Furthermore, the control of the drop-addition sequence: the reasonable design of the drop-addition sequence helps to avoid certain components from reacting prematurely with other components in the initial reaction, thereby ensuring the smooth progress of the reaction and the uniformity of the product.

[0043] Preferably, the alkaline agent used to adjust the pH value after the reaction is completed is a sodium hydroxide aqueous solution.

[0044] Furthermore, pH adjustment: adjusting the pH value after the reaction helps to neutralize residual acidic substances and stabilize the structure of the final product. Sodium hydroxide acts as an alkaline agent to buffer the reaction.

[0045] Preferably, the proportions of all the components are calculated by mass.

[0046] Furthermore, the calculation of mass fractions: the ratio of each component is calculated according to mass fractions, which can ensure the precise control of the reaction and the stability of the product quality.

[0047] The present invention provides a high-slump-retention water-reducing agent and a preparation method thereof. It has the following beneficial effects:

[0048] 1. The present invention adopts a combination of isopentenyl polyoxyethylene ether macromonomer and unsaturated carboxylic acid and its derivatives to form a polymer chain through polymerization reaction, thereby improving the dispersibility and stability of the water reducer. Compared with the single polymer system in the prior art, the present invention not only improves the dispersion effect, but also significantly enhances the slump retention of the water reducer in cement slurry, effectively delaying the loss of slump.

[0049] 2. The present invention adds alkyl polyglycoside and glucose to the formula to achieve synergistic effects, which not only improves the dispersibility of the water reducer, but also optimizes the uniform distribution of particles in the cement slurry, thereby improving the fluidity and stability of the final concrete. Compared with traditional water reducers, the present invention can achieve the same or even better water-reducing effect at a lower dosage, and has better economy and environmental friendliness.

[0050] 3. The present invention achieves precise control of the polymerization reaction by controlling the ratio and addition order of the oxidant, reducing agent and chain transfer agent, ensuring the stability of the molecular weight and molecular structure of the water reducer product. Unlike the widely used single free radical initiation system in the prior art, the reaction conditions of the present invention are more flexible and adjustable, solving the problem of excessive viscosity caused by excessive molecular weight.

[0051] 4. The present invention uses sodium hydroxide to adjust the pH value of the reaction solution, thereby ensuring the stability of the water reducer and its high efficiency in subsequent applications. Unlike the solutions in the prior art that require complex post-processing, the present invention avoids the generation of harmful by-products through simple and effective pH adjustment, making the water reducer have better long-term stability and applicability, and adapting to a wider range of construction environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. 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 making creative efforts are within the scope of protection of the present invention.

[0054] Please see the attached Figure 1 :

[0055] Example 1

[0056] Step 1:

[0057] Dissolve 300 parts of isopentenyl polyoxyethylene ether macromonomer and 20 parts of glucose in 350 parts of water to obtain Solution A. Add 2 parts of hydrogen peroxide to the solution as an oxidant, mix well, and let it stand for 30 minutes to ensure that the oxidant is completely dissolved and activated. In this step, the role of hydrogen peroxide is to promote the initiation of the polymerization reaction and improve the reaction efficiency.

[0058] Step 2:

[0059] Dissolve 1.5 parts of L-ascorbic acid (reducing agent) and 1.0 part of thioglycolic acid (chain transfer agent) in 88 parts of water to obtain solution B. Add solution B to solution A and stir evenly to ensure that the reducing agent can effectively work with the oxidizing agent to generate stable free radicals.

[0060] Step 3:

[0061] Mix 60 parts of acrylic acid with 40 parts of water to create Solution C. The acrylic acid in this solution, as the primary polymerization monomer, undergoes a cross-linking reaction with other components to form negatively charged polymer chains. This reaction is the core of the present invention, effectively improving the dispersibility and stability of the water reducer.

[0062] Step 4:

[0063] Dissolve 10 parts of APG0814 in 50 parts of water to obtain solution D. This solution contains the non-ionic surfactant APG0814, which can reduce the electrostatic repulsion between cement particles and improve the dispersibility of the water reducer.

[0064] Step 5:

[0065] Start stirring at 30°C and add solutions B, C, and D dropwise to solution A in sequence. The addition time is controlled within 2.5 hours. When adding the solutions dropwise, proper stirring and control of the addition speed can effectively prevent the solutions from reacting too quickly or too slowly, ensuring the uniformity and stability of the final product.

[0066] Step 6:

[0067] After the addition is complete, the mixture is stirred and reacted at a constant temperature of 30°C for 2 hours. During this period, the polymerization reaction proceeds further, and the generated polymer chains can effectively improve the dispersion and fluidity in the cement mixture.

[0068] Step 7:

[0069] After the reaction is complete, 6 parts of sodium hydroxide are added to adjust the pH to 6 to obtain the target product. The pH value is adjusted to ensure the stability of the water reducer, prevent degradation of the reaction product, and maintain its effectiveness during long-term storage and use.

[0070] Beneficial effects:

[0071] By adjusting the solution addition sequence and precisely controlling the reaction temperature, this example solves the problems of poor dispersibility and insufficient slump retention in traditional water reducers. The water reducer exhibits good dispersibility and high slump retention in concrete, effectively delaying the loss of concrete slump.

[0072] Example 2

[0073] Step 1:

[0074] 250 parts of isopentenyl polyoxyethylene ether macromonomer and 15 parts of glucose were dissolved in 350 parts of water to obtain solution A. 3 parts of sodium persulfate were added as an oxidant. At this time, the addition of sodium persulfate can quickly decompose and generate free radicals, initiating the polymerization reaction.

[0075] Step 2:

[0076] Dissolve 2 parts of ferrous sulfate and 0.8 parts of mercaptopropionic acid in 88 parts of water to obtain solution B. The role of ferrous sulfate and mercaptopropionic acid is to enhance the reducing power of the reaction, ensure the generation of stable free radicals, and control the reaction rate and chain growth.

[0077] Step 3:

[0078] Mix 50 parts of methacrylic acid with 30 parts of water to form solution C. Methacrylic acid, as an unsaturated carboxylic acid, has strong reactivity and can copolymerize with other monomers to improve the dispersibility and stability of the water reducer.

[0079] Step 4:

[0080] Dissolve 15 parts of APG0810 in 50 parts of water to obtain solution D. The APG0810 in this solution acts as a nonionic surfactant, which helps reduce the aggregation of cement particles and improves the fluidity and stability of concrete.

[0081] Step 5:

[0082] Stir at 40°C and add solutions B, C, and D dropwise to solution A over a period of about 3 hours. During the addition process, control the order and rate of addition to ensure a more uniform polymerization reaction and stable product quality.

[0083] Step 6:

[0084] After the addition is completed, the reaction is continued at a constant temperature of 40°C for 2 hours. After the polymerization reaction is completed, it is ensured that a high molecular structure is formed in the solution to improve the dispersibility of the cement.

[0085] Step 7:

[0086] After the reaction is completed, 8 parts of sodium hydroxide aqueous solution are added to the reaction solution to adjust the pH value to 5.5 to obtain the final product. By adjusting the pH value, the stability of the water reducer in different environments is ensured.

[0087] Beneficial effects:

[0088] By selecting appropriate oxidizing and reducing agents and controlling the reaction time and temperature, the water reducer of this embodiment achieves excellent dispersibility in cement slurry, reduces cement particle agglomeration, and enhances the fluidity and stability of concrete. Compared to conventional water reducers, this embodiment improves water reduction efficiency and exhibits significant slump retention.

[0089] Example 3

[0090] Step 1:

[0091] 280 parts of isopentenyl polyoxyethylene ether macromonomer and 10 parts of glucose were dissolved in 350 parts of water, and 1.5 parts of hydrogen peroxide were added as an oxidant to obtain solution A. The role of hydrogen peroxide is to start the polymerization reaction, provide the required free radicals, and help synthesize polymer chains.

[0092] Step 2:

[0093] Dissolve 3 parts of sodium bisulfite and 0.8 parts of thioglycerol in 88 parts of water to obtain solution B. Sodium bisulfate and thioglycerol provide reducing properties to ensure the smooth progress of the reaction and avoid chain growth that is too fast or too slow.

[0094] Step 3:

[0095] Mix 70 parts of hydroxyethyl acrylate with 30 parts of water to obtain solution C. As an important polymerization monomer, hydroxyethyl acrylate has a hydroxyl functional group that can cross-link with other monomers during the polymerization process to improve the hydrophilicity and stability of the water reducer.

[0096] Step 4:

[0097] 12 parts of APG0816 were dissolved in 50 parts of water to obtain solution D. As a nonionic surfactant, APG0816 can reduce the surface tension in the cement slurry and improve the dispersion effect of the water reducer.

[0098] Step 5:

[0099] While stirring at 35°C, solutions B, C, and D were added dropwise to solution A over a period of 2 hours. The appropriate temperature was maintained during the addition to ensure uniform polymerization and a controllable reaction rate.

[0100] Step 6:

[0101] After the addition is complete, continue the reaction at 35°C for 2 hours. Maintaining a constant temperature helps control the molecular weight and polymer chain growth, ensuring that the water reducer has an appropriate molecular weight distribution.

[0102] Step 7:

[0103] After the reaction is completed, 7 parts of sodium hydroxide are added to adjust the pH value to 6 to obtain a high slump-retention water reducer. By adjusting the pH value, the stability and effect of the water reducer under different pH conditions are ensured.

[0104] Beneficial effects:

[0105] This embodiment solves the problem of poor stability caused by incomplete reaction in traditional water reducers by finely adjusting the ratio of oxidizing agent to reducing agent. The water reducer has excellent dispersion effect in the cement mixture, significantly improving slump retention, and reducing the water consumption of cement.

[0106] Example 4

[0107] Step 1:

[0108] 320 parts of isopentenyl polyoxyethylene ether macromonomer and 18 parts of glucose were dissolved in 350 parts of water, and 2.5 parts of ammonium persulfate were added as an oxidant to obtain solution A. At this time, ammonium persulfate will generate free radicals by decomposition, thereby promoting the initiation of the polymerization reaction.

[0109] Step 2:

[0110] 3.5 parts of ferrous acetate and 1.2 parts of thioglycolic acid were dissolved in 88 parts of water to obtain solution B. The addition of ferrous acetate enhances the reducing nature of the reaction, helps generate stable free radicals, and controls the reaction rate.

[0111] Step 3:

[0112] Mix 50 parts of maleic anhydride with 40 parts of water to obtain solution C. Maleic anhydride, as an unsaturated carboxylic acid derivative, reacts with other monomers to form a stable polymer structure.

[0113] Step 4:

[0114] Dissolve 25 parts of APG1214 in 50 parts of water to obtain solution D. As a nonionic surfactant, APG1214 can effectively reduce the surface tension of cement particles and promote the fluidity of concrete.

[0115] Step 5:

[0116] With stirring at 50°C, solutions B, C, and D were added dropwise to solution A in sequence over a period of 2.5 hours. This step ensured the full reaction of the components and avoided overly rapid or incomplete reactions.

[0117] Step 6:

[0118] After the addition was completed, the reaction was maintained at a constant temperature of 50° C. for 2 hours to ensure that the polymerization reaction was complete and a uniform polymer chain structure was finally formed.

[0119] Step 7:

[0120] After the reaction is completed, 9 parts of sodium hydroxide aqueous solution is added to adjust the pH value to 6.5 to obtain the desired high slump retention water reducer. Adjusting the pH value helps ensure the long-term stability of the water reducer.

[0121] Beneficial effects:

[0122] By optimizing the reaction conditions, this embodiment enables the water reducer to react stably at higher temperatures, resulting in a final product with improved dispersibility and fluidity. Compared to conventional water reducers, this invention significantly improves slump retention while reducing water consumption, meeting the requirements of use in complex environments.

[0123] Comparative Example 1: Comparison between Example 1 (the present invention) and the conventional polymerization method in the prior art

[0124] Existing technical solutions:

[0125] Traditional methods for preparing water-reducing agents typically use a single monomer (such as acrylic acid or its derivatives) and relatively simple reaction conditions, typically conducting a single free radical polymerization reaction at elevated temperatures. A common practice is to directly use hydrogen peroxide as the oxidant and conduct the reaction at room temperature.

[0126] Comparison content:

[0127] In traditional solutions, the ratio of the oxidant (such as hydrogen peroxide) and the reducing agent is usually not strictly controlled, the reaction rate is fast, and the molecular weight is difficult to adjust.

[0128] The reaction time is long, and reaction at room temperature is likely to lead to incomplete polymerization, thus affecting the performance of the water reducer.

[0129] The lack of surfactants results in poor dispersion of cement particles and poor slump retention.

[0130] Comparative Example Preparation Method:

[0131] 300 parts of isopentenyl polyoxyethylene ether macromonomer and 20 parts of glucose were dissolved in 350 parts of water to obtain solution A.

[0132] 3 parts of hydrogen peroxide were added to solution A, the reaction temperature was controlled at room temperature (20-25° C.), and the polymerization reaction was directly carried out.

[0133] 40 parts of acrylic acid were directly added and the reaction continued.

[0134] The use of simple reducing agents (such as ferrous sulfate) is not precisely controlled, and the pH value is adjusted by adding sodium hydroxide after the reaction.

[0135] Comparative Example 2: Comparison of Example 2 (the present invention) with the traditional water reducer formula Prior art solution:

[0136] Traditional water reducers often use too many low-molecular-weight organic compounds, such as simple polysaccharide derivatives (e.g., glucose not used in combination with other surfactants), resulting in poor dispersion and slump retention. The reducing agents used are also usually simple single reducing agents.

[0137] Comparison content:

[0138] The traditional solution lacks the combined use of alkyl polysaccharides and non-ionic surfactants, which leads to charge accumulation between cement particles and unsatisfactory dispersion effect.

[0139] The ratio of oxidant and reducing agent is not precisely adjusted during the reaction, resulting in poor stability and dispersibility of the final product.

[0140] Without the use of low temperature or refined reaction process, the final water reducer has poor slump retention and is difficult to meet strict engineering application requirements.

[0141] Comparative Example Preparation Method:

[0142] 250 parts of isopentenyl polyoxyethylene ether macromonomer and 15 parts of glucose were dissolved in 350 parts of water to obtain solution A.

[0143] 2 parts of sodium persulfate were added to solution A, and the reaction temperature was controlled at 50°C.

[0144] 70 parts of acrylic acid and 30 parts of water were mixed to form solution B, which was added to solution A for reaction.

[0145] A simple surfactant was used without adding any alkyl polyglycoside, and the reaction was continued directly.

[0146] After the reaction was completed, sodium hydroxide was directly added to adjust the pH value without any post-treatment optimization.

[0147] Comparative Example 3: Comparison of Example 3 (the present invention) with the application of conventional surfactants

[0148] Existing technical solutions:

[0149] Traditional water reducers typically use simple surfactants during the preparation process and do not include non-ionic surfactants (such as APG) in the product. Traditional technologies rely on strong anionic or cationic surfactants, which can produce unstable interactions with other components in the cement slurry, affecting the long-term stability and dispersibility of the water reducer.

[0150] Comparison content:

[0151] The surfactants in traditional solutions use too much anionic or cationic surfactants, which may react with ions in cement slurry, resulting in poor stability and dispersibility of the water reducer in long-term use.

[0152] In contrast, the present invention uses non-ionic surfactants such as APG, which can avoid such unstable interactions and improve dispersibility and collapse retention.

[0153] Comparative Example Preparation Method:

[0154] 280 parts of isopentenyl polyoxyethylene ether macromonomer and 10 parts of glucose were dissolved in 350 parts of water to obtain solution A.

[0155] 3 parts of hydrogen peroxide were added to solution A, the reaction temperature was controlled at 30°C, and the polymerization reaction was started.

[0156] 10 parts of a simple surfactant (such as sodium dodecylbenzenesulfonate) was used as a dispersant, and no nonionic surfactant was used.

[0157] 70 parts of hydroxyethyl acrylate and 30 parts of water were mixed to form solution B, which was added to solution A for reaction.

[0158] Sodium hydroxide was directly added after the reaction to adjust the pH value without further optimizing the surfactant formulation.

[0159] Comparative Example 4: Comparison of Example 4 (the present invention) with conventional water reducer production process

[0160] Existing technical solutions:

[0161] Conventional water-reducing agent production processes typically operate at relatively high temperatures, with relatively simple control over reaction conditions and reaction time. High-temperature polymerization is commonly used, often using a single oxidizing or reducing agent. Inhomogeneities during the reaction and excessively high temperatures can lead to molecular chain instability, impacting the water-reducing agent's dispersibility and long-term slump retention.

[0162] Comparison content:

[0163] Conventional solutions use high temperatures (e.g., above 60°C) for polymerization reactions, which results in unstable molecular weight and the generation of by-products during the polymerization process, affecting the final performance of the water reducer.

[0164] Without careful pH adjustment and post-treatment after the reaction, the performance of the water reducer may decrease with the extension of storage time.

[0165] No chain transfer agent was used in the reaction to control the molecular weight, resulting in a higher molecular weight of the final product, which affected the fluidity and slump retention of the water reducer.

[0166] Comparative Example Preparation Method:

[0167] 320 parts of isopentenyl polyoxyethylene ether macromonomer and 18 parts of glucose were dissolved in 350 parts of water to obtain solution A.

[0168] 5 parts of hydrogen peroxide were added to solution A, and the reaction temperature was set to 60° C. to rapidly carry out the polymerization reaction.

[0169] 40 parts of maleic anhydride were mixed with 30 parts of water to obtain solution B, which was added to solution A for reaction.

[0170] After the reaction was completed, the pH value was adjusted directly by simple sodium hydroxide without further optimization process.

[0171] Experiment 1: Collapse resistance comparison test

[0172] Purpose of the experiment

[0173] The difference in slump retention in concrete between the water reducer prepared by Example 1 of the present invention and the conventional polymerization method (Comparative Example 1) in the prior art was compared.

[0174] Experimental procedures

[0175] Sample preparation: Water reducing agents were prepared according to the methods of Example 1 and Comparative Example 1. Example 1 used hydrogen peroxide and L-ascorbic acid as the oxidant and reducing agent, and combined them with an alkyl polyglycoside; while Comparative Example 1 only used hydrogen peroxide as the oxidant without adding any surfactant.

[0176] Concrete mix: Cement (500 g) and water (200 g) of the same mass were selected, and the water reducers of Example 1 and Comparative Example 1 were added respectively. The amount of water reducer used was 1.0% of the mass of cement.

[0177] Mixing concrete: The concrete samples were mixed in a mixer for 3 minutes to ensure uniform mixing.

[0178] Measuring initial slump: Use a standard slump tester (GB / T50080-2016) to test the slump of the mixed concrete.

[0179] Slump retention test: Take the second slump measurement 30 minutes and 1 hour after mixing. Record the slump loss rate of concrete.

[0180] Data recording: record the slump of each measurement and calculate the slump loss rate.

[0181] Experimental setup

[0182] Temperature: Room temperature (20-25°C)

[0183] Relative humidity: 50-60%

[0184] Test frequency: 30 minutes and 1 hour after stirring

[0185] Slump test standard: GB / T50080-2016

[0186] Experimental data

[0187]

[0188]

[0189] Table name: Collapse resistance comparison test results

[0190] Summarize

[0191] The test results of Experiment 1 demonstrate that the water-reducing agent in Example 1 of the present invention exhibits superior slump retention compared to Comparative Example 1. In slump measurements after 30 minutes and 1 hour, Example 1 exhibits lower slump loss rates. In particular, the slump loss rate after 1 hour was only 16.7%, significantly lower than the 44.0% of Comparative Example 1. This difference can be attributed to the use of alkyl polyglycosides in Example 1. As surfactants, alkyl polyglycosides effectively reduce the aggregation of cement particles, increase the fluidity of concrete, and maintain good fluidity and slump retention over a long period of time.

[0192] From a mechanistic perspective, the high-molecular-weight polymer structure in Example 1, through meticulously controlling the ratio of the oxidant to the reducing agent, forms a stable polymer chain, avoiding the viscosity issues associated with excessively high molecular weight. This enables the water-reducing agent to form a uniform dispersion in the cement slurry, making it less susceptible to reaggregation and providing a strong dispersing effect on cement particles. Compared to Comparative Example 1, which uses only hydrogen peroxide as the oxidant without a surfactant, Example 1 demonstrates significant advantages in dispersibility and slump retention.

[0193] Experimental results further demonstrate that the present invention, by optimizing the water-reducing agent formulation and reaction conditions, not only improves fluidity and slump retention, but also enhances the stability of concrete during construction. The water-reducing agent of Example 1, due to its superior dispersibility and stability, effectively prevents slump loss in concrete during transportation and construction, resolving the shortcomings of existing water-reducing agents in balancing high water reduction efficiency with slump retention.

[0194] Experiment 2: Dispersion comparison test

[0195] Purpose of the experiment

[0196] By measuring the particle size distribution of cement particles and comparing the difference in dispersibility between Example 2 of the present invention and a traditional water reducer (Comparative Example 2), it was verified that the surfactant (such as APG) improves the dispersibility of cement particles.

[0197] Experimental procedures

[0198] Sample preparation: Water reducing agents were prepared according to the methods of Example 2 and Comparative Example 2. In Example 2, APG0810 was used as a surfactant, while in Comparative Example 2, no nonionic surfactant was used.

[0199] Concrete paste ratio: Take the same mass of cement (500g) and water (200g), and add the water reducer in Example 2 and Comparative Example 2 respectively. The amount of water reducer used in both cases is 1.0% of the mass of cement.

[0200] Mix the concrete paste: Mix at a uniform speed in a mixer for 3 minutes to ensure that the water reducer is completely mixed with the cement.

[0201] Particle size distribution test: Take a certain amount of slurry sample and use a laser particle size analyzer (Malvern Mastersizer 3000) to perform a particle size distribution test to measure the size of cement particles and their distribution range.

[0202] Microscopic observation: Use an electron microscope to observe the cement particles in the concrete paste and record the degree of aggregation and uniformity of the particles.

[0203] Result analysis: The dispersibility of the cement particles in Example 2 and Comparative Example 2 was compared by analyzing the particle size distribution diagram and microscope images.

[0204] Experimental setup

[0205] Temperature: Room temperature (20-25°C)

[0206] Relative humidity: 50-60%

[0207] Laser particle size analyzer: Malvern Mastersizer 3000

[0208] Microscope observation: Particle observation using an electron microscope at 200 times magnification

[0209] Experimental data

[0210]

[0211]

[0212] Table name: Dispersion comparison test results

[0213] Summarize

[0214] The results of Experiment 2 show that the water-reducing agent of Example 2 of the present invention significantly outperformed that of Comparative Example 2 in terms of dispersibility. APG0810, a nonionic surfactant, played a crucial role in the water-reducing agent, significantly improving the dispersibility of cement particles. Compared to the formulation in Comparative Example 2 without a surfactant, the cement particles of Example 2 exhibited smaller D10, D50, and D90 particle sizes, a more uniform particle size distribution, lower aggregation, and a higher dispersibility evaluation score. This demonstrates that the use of APG0810 in the water-reducing agent effectively reduced electrostatic interactions between cement particles, enhanced their fluidity, and prevented particle aggregation.

[0215] Mechanistically, APG0810, as a surfactant, helps cement particles distribute evenly within the slurry by forming a stable double layer on the surface of cement particles or by reducing interparticle adsorption through hydrophobic interactions, thereby reducing particle agglomeration and sedimentation. Compared to Comparative Example 2, the cement slurry in Example 2 exhibited improved fluidity and uniformity after stirring, reflecting its enhanced dispersibility.

[0216] The experimental results show that the present invention effectively solves the problem of poor dispersibility in traditional water reducers due to the lack of effective surfactants by using APG0810. The water reducer of Example 2 not only improves the dispersibility of cement particles, but also provides better guarantees for the workability and stability of concrete.

[0217] Experiment 3: Reaction rate comparison test

[0218] Purpose of the experiment

[0219] By comparing the difference in polymerization reaction rate between Example 3 of the present invention and a conventional water reducer (Comparative Example 3), the effects of the precisely adjusted oxidant, reducing agent, and chain transfer agent in the present invention were tested.

[0220] Experimental procedures

[0221] Sample Preparation: Water reducers were prepared according to the methods of Example 3 and Comparative Example 3. Example 3 used hydrogen peroxide and L-ascorbic acid as the oxidant and reducing agent, and thioglycolic acid was added as a chain transfer agent. Comparative Example 3 used only hydrogen peroxide as the oxidant without the addition of a chain transfer agent.

[0222] Preparation of the reaction system: Take a certain amount of water (500 g) and add the water reducer in Example 3 and Comparative Example 3 respectively. Ensure that the amounts of oxidant and reducing agent used in both are the same, and the concentration of water reducer is 1.0% of the mass of cement.

[0223] Reaction rate test: Differential scanning calorimetry (DSC) was used to test the two reaction systems and record the heat flow and temperature changes during the reaction.

[0224] Record the reaction time: Starting from the addition of the oxidizing agent and reducing agent, record the time required to reach the maximum exotherm to determine the reaction rate.

[0225] Comparative analysis: Based on the DSC test results, the reaction rates of the two water reducers were compared to analyze the effect of the chain transfer agent in the water reducer of the present invention on the polymerization reaction rate.

[0226] Experimental setup

[0227] Temperature: Room temperature (20-25°C)

[0228] Reaction temperature range: 50-100℃

[0229] Equipment used: Differential Scanning Calorimeter (DSC)

[0230] Measuring time: heat flow is measured every 10 minutes

[0231] Experimental data

[0232]

[0233] Table Name: Reaction Rate Comparison Test Results

[0234] Summarize

[0235] The data from Experiment 3 demonstrate that the water reducer of Example 3 exhibits relatively stable polymerization reaction rates and a longer reaction time, with the time required to reach maximum exothermicity generally longer than that of Comparative Example 3. The reaction rates of Example 3 are generally lower than those of Comparative Example 3, indicating that the introduction of a chain transfer agent effectively slows the reaction rate and avoids the formation of byproducts associated with an overly rapid polymerization reaction. Compared to Comparative Example 3, the present invention, through precise control of the ratio of the oxidant to the reducing agent, provides a smoother reaction process, resulting in a more stable final water reducer product.

[0236] From a mechanistic perspective, the addition of thioglycolic acid in Example 3, acting as a chain transfer agent, inhibited the excessive growth of free radical chains, reduced the polymerization reaction rate, and resulted in a more uniform distribution of the final polymer chains. In contrast, Comparative Example 3 relied solely on an oxidant to initiate the reaction without the use of a chain transfer agent, resulting in a more rapid reaction and unstable polymer chains. This may have resulted in a higher molecular weight and viscosity, affecting the fluidity and dispersibility of the water reducer.

[0237] Experimental results further demonstrate that by optimizing reaction conditions during the water-reducing agent synthesis process, particularly the ratio of oxidant to reducing agent and the addition of a chain transfer agent, the present invention significantly improves the stability of the water-reducing agent, resulting in improved fluidity and dispersibility in practical applications. Compared to conventional technologies, the present invention provides a more controllable and stable method for preparing a water-reducing agent, ensuring the reliability of the product's performance under various environments.

[0238] Experiment 4: Concrete Strength Comparison Test

[0239] Purpose of the experiment

[0240] The effects of Example 4 of the present invention and a traditional water-reducing agent (Comparative Example 4) on the compressive strength of concrete in actual application were compared to verify the promoting effect of the water-reducing agent of the present invention on the cement hydration process.

[0241] Experimental procedures

[0242] Sample preparation: Water reducers were prepared according to the methods of Example 4 and Comparative Example 4. In Example 4, ammonium persulfate and sodium hydroxide were used to adjust the pH value to ensure good stability of the water reducer; while in Comparative Example 4, no chain transfer agent was used and the reaction conditions were relatively simple.

[0243] Concrete mix ratio: Select the same cement (500g) and water (200g), and add the water reducer in Example 4 and Comparative Example 4 respectively. The amount of water reducer is 1.0% of the mass of cement.

[0244] Mixing and pouring: Mix evenly in a mixer for 3 minutes to ensure that the cement and water reducer are completely mixed. Pour the mixture into a standard compression test mold and shake it gently to remove air bubbles.

[0245] Curing: Curing is carried out at 20℃, maintaining the relative humidity at around 95%, and the curing period is 28 days.

[0246] Compressive strength test: After 28 days, the compressive strength of the test pieces was tested using a compression testing machine in accordance with GB / T50081-2019.

[0247] Record data: record the compressive strength of the two samples and compare the compressive strength of Example 4 with that of Comparative Example 4.

[0248] Experimental setup

[0249] Temperature: 20℃

[0250] Relative humidity: 95%

[0251] Maintenance time: 28 days

[0252] Measurement standard: GB / T50081-2019

[0253] Test block size: 100mm×100mm×100mm

[0254] Experimental data

[0255]

[0256] Table name: Comparative test results of concrete compressive strength

[0257] Summarize

[0258] The results of Experiment 4 demonstrate that the water-reducing agent of Example 4 significantly improved the compressive strength of concrete. The compressive strength test values for Example 4 were generally above 58.2 MPa, while the compressive strength of Comparative Example 4 was only approximately 45.6 MPa. Even in repeated experiments, Example 4 maintained relatively high strength, demonstrating that the water-reducing agent of the present invention has a superior effect on promoting cement hydration. In contrast, the concrete strength of Comparative Example 4 after 28 days of curing was poor, and the test results fluctuated significantly, indicating a lack of stability.

[0259] From a mechanistic perspective, the water-reducing agent in Example 4 can more effectively promote the hydration reaction between cement and water by optimizing reaction conditions and improving the stability of the molecular structure. The polymer chain structure helps disperse cement particles, increasing the contact area between cement particles and water, thereby accelerating the hydration process of cement. This process produces more hydration products, enhancing the hardness and strength of concrete. In contrast, the traditional water-reducing agent (Comparative Example 4) lacks effective dispersibility, causing cement particles to agglomerate in the cement paste, resulting in incomplete hydration reaction and a subsequent decrease in compressive strength.

[0260] Combining experimental data with mechanistic analysis, the water-reducing agent provided in Example 4 of the present invention significantly improves the mechanical properties of concrete due to its excellent dispersibility and cement hydration-promoting effect. Compared with traditional water-reducing agents, the present invention not only improves the fluidity of concrete but also effectively enhances its long-term stability and compressive strength. This result demonstrates the potential application value of the present invention in the construction industry.

[0261] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high slump retention water reducer, characterized in that: include: 300 parts of isopentenyl polyoxyethylene ether macromonomer; 40-120 parts of unsaturated carboxylic acids and their derivatives; 5-25 parts of glucose; 5-40 parts of alkyl polyglycosides; 0.3-4.0 parts of oxidizing agent; 0.3-4.0 parts of reducing agent; Chain transfer agent 0.6-3.0 parts; 5-12 parts of sodium hydroxide; Water is used as a solvent for solution preparation and reaction.

2. A high slump retention water reducer according to claim 1, characterized in that, The unsaturated carboxylic acid and its derivatives are at least one of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, and maleic anhydride.

3. A high slump retention water reducer according to claim 1, characterized in that, The alkyl polyglycoside is an alkyl polyglycoside generated by the reaction of C8-C16 fatty alcohol and glucose, and is selected from at least one of APG0810, APG0814, APG0816, and APG1214.

4. A method for preparing a high slump retention water reducer, applied to a high slump retention water reducer according to claims 1-3, characterized in that: The steps include: A pre-solution is prepared by dissolving 300 parts of isopentenyl polyoxyethylene ether macromonomer, 6-25 parts of glucose, and 0.3-4.0 parts of an oxidant in 350 parts of water to prepare solution A; Dissolve 0.3-4.0 parts of reducing agent and 0.6-3.0 parts of chain transfer agent in 88 parts of water to prepare solution B; Dissolve 40-120 parts of unsaturated acid and its derivatives in 40 parts of water to prepare solution C; Dissolve 5-40 parts of alkyl polyglycoside in 50 parts of water to prepare solution D; Polymerization reaction: Stir at 30-55°C and add solutions B, C, and D to solution A dropwise in sequence for 2.5-3 hours; After the addition is completed, continue the reaction at a constant temperature of 30-55°C for 2 hours; After the reaction, 5-12 parts of sodium hydroxide are added to the reaction solution to adjust the pH to 5-7 to obtain the high slump retention water reducer.

5. The method for preparing a high slump retention water reducer according to claim 4, wherein: The oxidant is at least one of hydrogen peroxide, sodium persulfate, potassium persulfate, and ammonium persulfate.

6. The method for preparing a high slump retention water reducer according to claim 4, wherein: The reducing agent is at least one of L-ascorbic acid, sodium bisulfite, ferrous sulfate, sodium sulfite, ferrous chloride, ferrous acetate, sodium hypophosphite, and sodium formaldehyde sulfenate.

7. The method for preparing a high slump retention water reducer according to claim 4, wherein: The chain transfer agent is at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, thioglycerol, and thiomalic acid.

8. The method for preparing a high slump retention water reducer according to claim 4, wherein: The order of adding the solutions B, C and D is B first, then C and then D, and the starting time of the three is the same.

9. The method for preparing a high slump retention water reducer according to claim 4, wherein: After the reaction is completed, the alkaline agent used to adjust the pH value is sodium hydroxide aqueous solution.

10. The method for preparing a high slump retention water reducer according to claim 4, wherein: The proportions of all the components are calculated by mass.

Images