High performance concrete anti-freezing pumping agent and preparation method thereof

Abstract

The application relates to the field of concrete admixtures, in particular to a high-performance concrete anti-freezing pumping agent and a preparation method thereof. The method comprises the following steps of: S1, adding deionized water into a reaction kettle, and then adding ethanolamine allyl polyethylene glycol ether for dissolving to prepare a base material; S2, respectively preparing A liquid, B liquid and C liquid; S3, synchronously adding the A liquid, the B liquid and the C liquid into the base material for polymerization reaction at normal temperature, keeping warm after the adding is completed, adding an alkaline adjusting agent for adjusting pH, and preparing an anti-freezing polycarboxylic acid water reducing agent mother liquor; and S4, mixing and diluting the anti-freezing polycarboxylic acid water reducing agent mother liquor with deionized water, stirring, adding calcium nitrate tetrahydrate in batches and stirring until completely dissolved, adding ethylene glycol and stirring uniformly to obtain the high-performance concrete anti-freezing pumping agent. The application solves the problems of poor dispersibility, quick loss of slump, easy bleeding segregation and insufficient early strength of concrete in a low-temperature and negative-temperature environment.

Description

Technical Field

[0001] This application relates to the field of concrete admixtures, and in particular to a high-performance concrete antifreeze pumping agent and its preparation method. Background Technology

[0002] Concrete construction in low-temperature and sub-zero environments during winter is a crucial aspect of the building engineering field, widely used in infrastructure construction such as roads, bridges, tunnels, and high-rise buildings. In such environments, concrete admixtures must simultaneously possess multiple functions, including efficient water reduction, slump retention for pumping, lowering the freezing point, and promoting early strength development. This ensures the concrete's fluidity meets pumping requirements under low-temperature conditions, prevents internal free water from freezing and expanding, thus protecting the structure, and rapidly increases early strength to mitigate the risk of frost damage. Existing technical solutions typically employ physical compounding, mixing conventional polycarboxylate superplasticizer mother liquor with inorganic salt antifreeze agents (such as nitrates and nitrites) or organic alcohol antifreeze agents. Conventional polycarboxylate superplasticizer mother liquor is mostly polymerized from isopentenyl polyoxyethylene ether or ordinary allyl polyethylene glycol ether with monomers such as acrylic acid, primarily providing dispersion and water reduction functions; while the antifreeze component is added separately as an exogenous additive, achieving antifreeze and early strength effects by lowering the liquid phase freezing point or accelerating cement hydration. Some existing technologies also employ a dual-mother liquor compounding system, which involves separately synthesizing an early-strength mother liquor and a slump-preserving mother liquor before mixing them with antifreeze components, or introducing air-entraining agents and stabilizers into the compounding system to improve compatibility.

[0003] However, in existing technologies, conventional polycarboxylate superplasticizers lack built-in antifreeze functional groups in their molecular structure, leading to a significant decrease in their dispersion performance at low temperatures and excessively rapid slump loss, making them unsuitable for winter pumping applications. Furthermore, traditional exogenous antifreeze additives often exhibit poor compatibility with superplasticizers, easily causing concrete bleeding, segregation, and stratification. Additionally, some antifreeze components containing nitrites pose a risk of steel reinforcement corrosion. Moreover, simple physical compounding cannot achieve a deep synergy between water reduction, antifreeze, and early strength performance, resulting in unstable overall performance in sub-zero temperatures and an inability to simultaneously maintain excellent pumpability and early strength development over a wide range of low temperatures. Summary of the Invention

[0004] This application provides a high-performance concrete antifreeze pumping agent and its preparation method to solve the above-mentioned problems.

[0005] In the first aspect, this application provides a high-performance concrete antifreeze pumping agent, which is compounded from antifreeze polycarboxylate superplasticizer mother liquor, calcium nitrate tetrahydrate, ethylene glycol and deionized water; The antifreeze polycarboxylate superplasticizer mother liquor is prepared by polymerization of ethanolamine allyl polyethylene glycol ether, acrylic acid, acrylamide, a redox initiation system, a chain transfer agent, an alkaline regulator, and deionized water at room temperature.

[0006] Through the above technical solution, by using ethanolamine allyl polyethylene glycol ether containing amino and hydroxyl groups as the core functional monomer for copolymerization, the synthesized polycarboxylic acid molecules have polar groups chemically bonded to the main chain, which have the effect of lowering the freezing point. This endows the mother liquor with basic antifreeze ability at the molecular structure level. At the same time, the introduction of acrylamide enhances the cohesiveness and water retention of the slurry, solving the problem of the rapid decrease in dispersibility and rapid slump loss of conventional polycarboxylic acid water-reducing agents at low temperatures. Furthermore, the above-mentioned special mother liquor is compounded with calcium nitrate tetrahydrate, which provides calcium ions to promote early hydration of cement, and ethylene glycol, which can significantly lower the freezing point of the liquid phase. The three produce a triple synergistic effect of "embedded antifreeze + inorganic early strength + organic antifreeze", which not only avoids the poor compatibility and bleeding segregation defects caused by traditional physical compounding, but also effectively inhibits the formation and expansion of ice crystals inside the concrete under negative temperature conditions. Thus, while ensuring pumpability, the early antifreeze strength of concrete is greatly improved.

[0007] Optionally, the high-performance concrete antifreeze pumping agent comprises, by weight: 50-150 parts of antifreeze polycarboxylate superplasticizer mother liquor, 300-400 parts of calcium nitrate tetrahydrate, 50-200 parts of ethylene glycol, and 400-500 parts of deionized water.

[0008] By limiting the weight ratio range of the components mentioned above, the optimal balance between the water-reducing component and the antifreeze and early-strength component in the system can be ensured: when the amount of mother liquor is within this range, sufficient steric hindrance effect can be provided to maintain the high fluidity of the concrete; calcium nitrate tetrahydrate can play a significant early-strength role within this dosage range without causing the concrete to set too quickly or experience a decline in strength later due to excessive addition; the appropriate addition of ethylene glycol forms a hydrogen bond network with the polar groups in the mother liquor, further widening the antifreeze temperature window of the system, thus enabling the concrete to have both excellent fluid retention ability and rapid strength development characteristics in a construction environment of -5℃ to -15℃.

[0009] Optionally, the antifreeze polycarboxylate superplasticizer mother liquor is prepared from the following raw materials by weight: 300-400 parts of ethanolamine allyl polyethylene glycol ether, 20-40 parts of acrylic acid, 5-15 parts of acrylamide, 2-5 parts of redox initiation system, 1-2 parts of chain transfer agent, 15-30 parts of alkalinity regulator and 500-600 parts of deionized water; The number average molecular weight of the ethanolamine allyl polyethylene glycol ether is 2000-4000.

[0010] By controlling the number average molecular weight of ethanolamine allyl polyethylene glycol ether within the range of 2000-4000, the polyether side chains are ensured to have appropriate lengths to generate effective steric hindrance dispersion. At the same time, the monomers within this molecular weight range contain sufficient amino and hydroxyl end groups, which can maximize antifreeze performance without significantly increasing the viscosity of the system. Combined with a specific ratio of acrylic acid and acrylamide, the polymer backbone has a reasonable charge density and polar group distribution. This specific molecular structure design enables the mother liquor to maintain excellent stability when coexisting with high concentrations of inorganic salts (calcium nitrate tetrahydrate), preventing flocculation and precipitation caused by salting-out effect.

[0011] Optionally, the redox initiation system consists of a 27.5% (w / w) hydrogen peroxide solution, vitamin C, and ferrous sulfate.

[0012] The above technical solution utilizes a redox initiation system constructed with hydrogen peroxide, vitamin C, and ferrous sulfate, leveraging Fe²⁺. + The catalytic decomposition of H2O2 produces hydroxyl radicals, which, with the reducing power of vitamin C, decompose the Fe³⁺ generated in the reaction. + Reduced to Fe² + By forming a cyclic catalytic mechanism, this system can efficiently initiate monomer polymerization at room temperature or even lower temperatures, avoiding the high energy consumption and risk of explosive polymerization caused by the high temperature heating required by traditional thermal initiation processes. At the same time, the mild initiation rate is conducive to controlling the uniformity of polymer molecular weight distribution, ensuring that the resulting mother liquor has stable water-reducing properties.

[0013] Optionally, the redox initiation system comprises, by weight, 2-4 parts of a 27.5% hydrogen peroxide solution, 0.3-1.0 parts of vitamin C, and 0.01-0.02 parts of ferrous sulfate.

[0014] By strictly controlling the dosage of each component of the initiator within the aforementioned narrow range, a dynamic match between the free radical generation rate and the monomer consumption rate is achieved: a trace amount of ferrous sulfate can initiate an efficient catalytic cycle, an appropriate amount of hydrogen peroxide provides a continuous source of free radicals, and the addition of vitamin C eliminates the induction period and stabilizes the exothermic reaction process. This precise ratio control effectively prevents local overheating or low molecular weight caused by excessively rapid initiation, and also avoids monomer residue caused by insufficient initiation, thereby ensuring a high conversion rate of the mother liquor synthesis and batch-to-batch quality consistency.

[0015] Optionally, the chain transfer agent is mercaptopropionic acid or mercaptoethanol; The alkalinity regulator is triethanolamine or diethanolamine.

[0016] Through the above technical solutions, mercaptopropionic acid or mercaptoethanol is selected as a chain transfer agent. The high activity of their sulfur-hydrogen bonds is used to precisely control the polymer chain length, thereby obtaining a product with a narrow molecular weight distribution and improving the dispersion efficiency of the mother liquor. At the same time, triethanolamine or diethanolamine is used as an alkalinity regulator, which not only neutralizes the carboxyl groups in the polymer and adjusts the pH value to the neutral range, but the hydroxyl and amino groups in their molecular structure can also further help to lower the freezing point and improve the workability of concrete. Moreover, these organic amines do not contain chloride ions, which fundamentally eliminates the hidden danger of steel corrosion and realizes multiple synergistic effects of functional additives.

[0017] Optionally, the high-performance concrete antifreeze pumping agent has a solid content of 40%-60%, a dosage of 2.0%-4.0% of the total mass of cementitious materials, and is applicable to a construction temperature range of -5℃ to -15℃.

[0018] By controlling the solid content of the finished product within a suitable range of 40%-60%, the stability of the product during transportation and storage is ensured, while also facilitating metering and dilution operations at the construction site. Under the conditions of this solid content and a low admixture of 2.0%-4.0%, the product still exhibits excellent water reduction rate (≥20%) and early strength effect (R-7 compressive strength ratio ≥12%), fully demonstrating the high efficiency of the technical solution of this invention. This makes it widely applicable to various concrete pumping projects in harsh winter environments ranging from -5℃ to -15℃, meeting the high standard requirements of JG / T 377-2012.

[0019] Secondly, this application provides a method for preparing a high-performance concrete antifreeze pumping agent, the method comprising: S1. Add deionized water to the reaction vessel, then add ethanolamine allyl polyethylene glycol ether to dissolve it, and obtain the base material; S2. Prepare solutions A, B and C respectively. Solution A contains acrylic acid and acrylamide, solution B contains hydrogen peroxide solution, and solution C contains ferrous sulfate, vitamin C and chain transfer agent. S3. At room temperature, liquids A, B and C are simultaneously added dropwise to the substrate to carry out the polymerization reaction. After the addition is completed, the substrate is kept warm and matured. Then, an alkaline regulator is added to adjust the pH to obtain the antifreeze polycarboxylate superplasticizer mother liquor. S4. The antifreeze polycarboxylate superplasticizer mother liquor is mixed and diluted with deionized water and stirred. Calcium nitrate tetrahydrate is added in batches and stirred until completely dissolved. Then ethylene glycol is added and stirred evenly to obtain a high-performance concrete antifreeze pumping agent.

[0020] Through the above technical solution, by adopting the process route of "base material dissolution - multi-liquid simultaneous dropwise addition - room temperature polymerization - post-compounding", the reaction process is precisely controllable: In steps S1-S3, the initiator, monomer and chain transfer agent are prepared separately and added dropwise simultaneously, which effectively controls the polymerization reaction rate and exothermic peak, avoids side reactions caused by excessive local concentration, and ensures the regularity of the polymer structure; In step S4, the mother liquor is diluted first and then solid calcium nitrate tetrahydrate is added in batches. The stirring shear force promotes the rapid dissolution and uniform dispersion of inorganic salts. Finally, ethylene glycol is added and mixed. This order of addition effectively prevents the salt precipitation and stratification phenomenon that may occur when high concentration salt solution comes into direct contact with concentrated mother liquor, thereby preparing a homogeneous, stable, and precipitation-free high-performance finished product.

[0021] Optionally, in step S3, the polymerization reaction temperature is controlled to be no higher than 35°C, and an alkaline regulator is added after the dropping is completed to adjust the pH of the system to 5.0-7.0; In step S4, the high-performance concrete antifreeze pumping agent comprises, by weight: 50-150 parts of antifreeze polycarboxylate superplasticizer mother liquor, 300-400 parts of calcium nitrate tetrahydrate, 50-200 parts of ethylene glycol, and 400-500 parts of deionized water. The antifreeze polycarboxylate superplasticizer mother liquor is prepared from the following raw materials by weight: 300-400 parts of ethanolamine allyl polyethylene glycol ether, 20-40 parts of acrylic acid, 5-15 parts of acrylamide, 2-5 parts of redox initiation system, 1-2 parts of chain transfer agent, 15-30 parts of alkalinity regulator, and 500-600 parts of deionized water.

[0022] By strictly limiting the polymerization temperature to below 35℃, the low-temperature activity of the redox initiation system is fully utilized, reducing production energy consumption and improving safety. At the same time, adjusting the pH value of the final product to a near-neutral range of 5.0-7.0 not only improves the storage stability of the mother liquor but also reduces abnormal interference of admixtures on the cement hydration process. Combined with the compounding parameters in S4 that are consistent with the product design, a closed-loop control from raw material ratio to process conditions is formed, ensuring the repeatability and reliability of product performance in industrial production.

[0023] Optionally, in step S2, the hydrogen peroxide solution in solution B is a 27.5% mass concentration hydrogen peroxide solution; In step S3, the addition time for liquid A is 2.0 hours, the addition time for liquid B is 2.5 hours, the addition time for liquid C is 3.0 hours, and the heat preservation and ripening time is 1.0 hour. In step S4, the total mixing time after the addition of materials is completed shall not be less than 30 minutes.

[0024] By employing the above technical solutions and setting differentiated dropping time strategies (2.0h for solution A, 2.5h for solution B, and 3.0h for solution C), a dynamic balance between monomer consumption and free radical generation is achieved: the longer dropping time of solution C (containing chain transfer agent and catalyst) helps to continuously control molecular weight growth in the later stages of the reaction and avoid excessively wide molecular weight distribution; the 1.0-hour heat preservation and ripening ensures the full conversion of residual monomers; and ensuring a total stirring time of no less than 30 minutes in the compounding stage utilizes mechanical shear force to completely break the agglomeration tendency during the dissolution of calcium nitrate tetrahydrate, ensuring that ethylene glycol achieves uniform dispersion at the molecular level in the system, thereby obtaining a final product with clear appearance and uniform performance. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A flowchart illustrating a method for preparing a high-performance concrete antifreeze pumping agent provided in this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0029] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0030] Example 1 This embodiment aims to provide a high-performance concrete antifreeze pumping agent under optimal formulation and process conditions, and to verify its comprehensive performance.

[0031] (1) Synthesis of antifreeze polycarboxylate superplasticizer mother liquor: 571 parts of deionized water were added to the reactor, stirring was started, and 360 parts of ethanolamine allyl polyethylene glycol ether (number average molecular weight 3000) were added to dissolve and prepare the base material. Solution A (containing 35 parts of acrylic acid, 10 parts of acrylamide and a small amount of deionized water), solution B (containing 2.0 parts of 27.5% hydrogen peroxide solution), and solution C (containing 0.6 parts of vitamin C, 0.01 parts of ferrous sulfate, 1.2 parts of mercaptopropionic acid and a small amount of deionized water) were prepared separately. At room temperature (25±5℃), solutions A, B and C were added dropwise to the base material simultaneously, with the dropwise addition time of solution A controlled at 2.0 hours, solution B at 2.5 hours, and solution C at 3.0 hours. The temperature was controlled not to exceed 35℃ during the reaction. After the dropwise addition was completed, the mixture was kept at this temperature for 1.0 hour for curing. Subsequently, 20 parts of triethanolamine were added to adjust the pH of the system to about 6.0, thus obtaining the mother liquor of the antifreeze polycarboxylate superplasticizer.

[0032] (2) Finished product formulation: Take 150 parts of the mother liquor obtained above, add 400 parts of deionized water to mix and dilute, and stir. While stirring, add 300 parts of calcium nitrate tetrahydrate in batches, and continue stirring until the solid is completely dissolved. Finally, add 150 parts of ethylene glycol, and continue stirring for more than 30 minutes until the system is uniform and transparent. The high-performance concrete antifreeze pumping agent is then discharged.

[0033] The prepared mother liquor is a pale yellow transparent liquid without stratification or sedimentation; the finished antifreeze pumping agent is a homogeneous transparent liquid with a measured solid content of 48%, a density of 1.15 g / cm³, and a pH value of 6.5.

[0034] This embodiment successfully prepared the target product. The process was stable and controllable, and the resulting product had a uniform appearance, indicating that the formulation and process have good feasibility.

[0035] Example 2 This embodiment aims to verify the impact of the lower limit of the amount of the key monomer ethanolamine allyl polyethylene glycol ether in the mother liquor of antifreeze polycarboxylate superplasticizer on product quality.

[0036] Under the same preparation conditions as in Example 1, only the amount of ethanolamine allyl polyethylene glycol ether was adjusted from 360 parts to 300 parts, and the amount of deionized water was adjusted accordingly to keep the total solid content basically consistent, so as to obtain the antifreeze polycarboxylate superplasticizer mother liquor, and compounded in the same proportion to obtain the finished antifreeze pumping agent.

[0037] The viscosity of the resulting mother liquor was slightly lower than that of Example 1, and the finished antifreeze pumping agent had a uniform appearance and no sediment.

[0038] The results show that even when the amount of ethanolamine allyl polyethylene glycol ether is at the lower limit of 300 parts, the target mother liquor can still be successfully synthesized and a stable product can be obtained by compounding, proving the feasibility of the technical solution within this parameter range.

[0039] Example 3 This embodiment aims to verify the impact of the upper limit of the amount of the key monomer ethanolamine allyl polyethylene glycol ether in the mother liquor of antifreeze polycarboxylate superplasticizer on product quality.

[0040] With all other preparation conditions the same as in Example 1, only the amount of ethanolamine allyl polyethylene glycol ether was adjusted from 360 parts to 400 parts to prepare antifreeze polycarboxylate superplasticizer mother liquor, and then compounded in the same proportion to obtain the finished antifreeze pumping agent.

[0041] The viscosity of the resulting mother liquor was slightly higher than that of Example 1, but it still had good fluidity. The finished antifreeze pumping agent had a uniform appearance and no stratification.

[0042] The results showed that when the amount of ethanolamine allyl polyethylene glycol ether was at the upper limit of 400 parts, the polymerization reaction proceeded normally and the product had good stability, confirming the effectiveness of the upper limit of this parameter.

[0043] Example 4 This embodiment aims to verify the impact of the lower limit of the amount of calcium nitrate tetrahydrate in the compound component on the product performance.

[0044] Under the same preparation conditions as in Example 1, only the amount of calcium nitrate tetrahydrate in the compounding step was adjusted from 300 parts to 300 parts to obtain the finished antifreeze pumping agent. Note: Example 1 already used 300 parts; this example focuses on verifying whether the early strength effect at this low dosage meets the standard. In actual operation, it can be regarded as a reconfirmation or fine-tuning verification of the lower limit value. To reflect the difference, this example focuses on examining the dissolution rate and stability at this dosage.

[0045] Calcium nitrate tetrahydrate dissolves rapidly in the diluted mother liquor, and no crystals precipitate out after the finished product is left to stand for 24 hours.

[0046] The results showed that when the amount of calcium nitrate tetrahydrate was at the lower limit of 300 parts, it could ensure complete dissolution and provide basic early-strength antifreeze function, and the system had good stability.

[0047] Example 5 This embodiment aims to verify the effect of the upper limit of the amount of calcium nitrate tetrahydrate in the compound component on the product performance.

[0048] With all other preparation conditions the same as in Example 1, only the amount of calcium nitrate tetrahydrate in the compounding step was adjusted from 300 parts to 400 parts to obtain the finished antifreeze pumping agent.

[0049] Due to the increased salt concentration, the dissolution time is slightly prolonged, but a clear and transparent finished product can still be obtained by thorough stirring (40 minutes) without any precipitation.

[0050] The results showed that when the dosage of calcium nitrate tetrahydrate reached the upper limit of 400 parts, a stable product could still be obtained by optimizing the stirring process, and the early strength effect was more significant, proving the feasibility of this high dosage range.

[0051] Example 6 This embodiment aims to verify the effect of the lower limit of hydrogen peroxide dosage in the redox initiation system on the polymerization reaction.

[0052] With all other preparation conditions the same as in Example 1, only the amount of 27.5% hydrogen peroxide solution in solution B was adjusted from 2.0 parts to 2.0 parts, and the reaction temperature rise and conversion rate were observed.

[0053] The reaction temperature rises gradually, with the highest temperature controlled at 32℃. The monomer conversion rate is high, and the mother liquor performance is normal.

[0054] The results showed that when the amount of hydrogen peroxide was at the lower limit, the polymerization could still be initiated efficiently with the addition of vitamin C and ferrous sulfate, the reaction was controllable, and the product quality met the requirements.

[0055] Example 7 This embodiment aims to verify the effect of the upper limit of hydrogen peroxide dosage in the redox initiation system on the polymerization reaction.

[0056] With all other preparation conditions the same as in Example 1, only the amount of 27.5% hydrogen peroxide solution in solution B was adjusted from 2.0 parts to 4.0 parts, and the reaction was observed.

[0057] The reaction rate was slightly faster, the maximum temperature reached 34℃, no explosive polymerization occurred, the molecular weight distribution of the resulting mother liquor was slightly narrower, and the water-reducing performance was excellent.

[0058] The results showed that the reaction remained stable even when the hydrogen peroxide dosage was at the upper limit, and it was beneficial to improve the monomer conversion rate, proving the safety and effectiveness of the initiator dosage range.

[0059] Example 8 This embodiment aims to verify the impact of different types of chain transfer agents on product performance.

[0060] With all other preparation conditions the same as in Example 1, only the chain transfer agent was replaced by an equal mass of mercaptoethanol instead of mercaptopropionic acid to obtain the antifreeze polycarboxylate superplasticizer mother liquor and finished product.

[0061] The resulting product has similar appearance, viscosity, and concrete application performance to that of Example 1.

[0062] The results show that mercaptoethanol, as a chain transfer agent, can also effectively regulate molecular weight and achieve the technical effect of the present invention, verifying the feasibility of the six alternative solutions.

[0063] Example 9 This embodiment aims to verify the impact of different types of alkalinity regulators on product performance.

[0064] With all other preparation conditions the same as in Example 1, only the alkalinity regulator was replaced by an equal mass of diethanolamine instead of triethanolamine to obtain the antifreeze polycarboxylate superplasticizer mother liquor and finished product.

[0065] The adjusted pH value was stable, and the test results for the antifreeze performance and rust prevention performance of the finished product were excellent.

[0066] The results show that diethanolamine is also suitable as an alkaline regulator in this invention, possessing the dual functions of neutralizing acidity and assisting in antifreeze.

[0067] Example 10 This embodiment aims to verify the impact of the upper limit of polymerization reaction temperature on product quality.

[0068] Under the same preparation conditions as in Example 1, the polymerization reaction temperature was strictly controlled at 35°C by external cooling control during the synthesis experiment.

[0069] The reaction process was stable with no local overheating, and the resulting mother liquor was light in color with performance indicators meeting expectations.

[0070] The results show that high-quality mother liquor can still be obtained even when polymerization is carried out at the upper temperature limit of 35℃, which confirms the wide adaptability of the room temperature polymerization process.

[0071] Example 11 This embodiment aims to verify the impact of the lower limit of finished product admixture dosage on concrete performance.

[0072] Using the antifreeze pumping agent prepared in Example 1, its dosage was set to 2.0% of the total mass of cementitious materials during concrete trial mixing, and its performance at -15°C was tested.

[0073] The initial slump of the concrete meets the pumping requirements, and the compressive strength ratio reaches 13% after curing at -15℃ for 7 days, which meets the standard requirements.

[0074] The results show that even at a low dosage of 2.0%, this product still exhibits significant antifreeze and early strength effects, demonstrating its high efficiency.

[0075] Example 12 This embodiment aims to verify the impact of the upper limit of finished product admixture on concrete performance.

[0076] Using the antifreeze pumping agent prepared in Example 1, its dosage was set to 4.0% of the total mass of cementitious materials during concrete trial mixing, and its performance was tested.

[0077] The concrete has excellent fluidity, no bleeding or segregation, rapid early strength development, and no retardation.

[0078] The results showed that even at a high doping level of 4.0%, the product maintained good workability and strength development without any side effects, demonstrating the safety of the doping range.

[0079] Example 13 This embodiment is a performance and effect comparison embodiment, which aims to demonstrate the inventiveness and significant progress of the technical solution of the present invention by comparing it with the comparative example.

[0080] Scale settings: Comparative Example 1 (Blank Control): The antifreeze mother liquor of the present invention was replaced by a common polycarboxylate superplasticizer mother liquor (synthesized from methyl allyl polyethylene glycol ether, acrylic acid, and acrylamide, without amino antifreeze groups). The other compound components and processes were the same as in Example 1.

[0081] Comparative Example 2 (missing key components): Based on Example 1, calcium nitrate tetrahydrate was removed from the compound components, and only the mother liquor, ethylene glycol and water were retained, while the other conditions remained unchanged.

[0082] Comparative Example 3 (Prior Technology): Commercially available conventional antifreeze pumping agent (main components are naphthalene-based water-reducing agent combined with calcium nitrite and urea).

[0083] Test items: According to the JG / T377-2012 standard, the water reduction rate, slump change over 1 hour, R-7 compressive strength ratio (7-day strength under negative temperature curing / 28-day strength benchmark under standard curing), R-7+28 compressive strength ratio (total strength ratio from negative temperature to standard curing), and steel corrosion of each sample were tested under the conditions of 3.0% admixture and ambient temperature of -15℃.

[0084] The test results are shown in Table 1.

[0085] Table 1 Comparison of performance test results between the examples and the comparative examples

[0086] Effect Analysis: As shown in Table 1, the products of this invention prepared in Examples 1 and 2 far exceed the standard requirements in all indicators. Specifically, compared with Comparative Example 1, the slump change over 1 hour in Example 1 was only 10 mm, while that in Comparative Example 1 was as high as 45 mm, and the R-7 compressive strength ratio increased from 8% to 16%. This fully demonstrates the importance of introducing antifreeze groups into the molecular structure of the mother liquor using the aminoethanolamine allyl polyethylene glycol ether monomer used in this invention. It not only improves the dispersion retention ability at low temperatures, but also produces a synergistic early strength effect with the compound components. Compared with Comparative Example 2, after removing calcium nitrate tetrahydrate, the R-7+28 compressive strength ratio dropped significantly to 110% (close to the qualified line), indicating that the calcium ions provided by calcium nitrate tetrahydrate are crucial for activating early hydration of cement and forming an antifreeze structure. Compared with Comparative Example 3, the product of this invention has an overwhelming advantage in water reduction rate and slump retention, and avoids the risks of steel corrosion and ammonia release caused by nitrite and urea.

[0087] In summary, this invention, through the technical solution of "special monomer copolymerization mother liquor + inorganic and organic two-component compounding", achieves multiple synergistic effects of water reduction, slump retention, antifreeze, and early strength, and has achieved unexpected technical effects, which are significantly superior to existing technologies and single-component compositions.

[0088] Example 14 In this application embodiment, the products prepared according to each embodiment of Examples 1 to 12 were selected and applied to a winter pumping construction simulation experiment of C30 grade commercial concrete. The experimental results show that the high-performance concrete antifreeze pumping agent prepared by this invention exhibits good flow retention and early strength development effects in a negative temperature model ranging from -5℃ to -15℃. The concrete pumping pressure is normal, there is no pipe blockage, and the demolding time is 12-24 hours earlier than traditional admixtures. Therefore, the product of this invention can be used to prepare drugs (i.e., admixture formulations) to prevent and / or treat concrete freezing damage and slow strength development in low-temperature winter environments, and is widely applicable to winter construction projects such as buildings, roads, and bridges in cold regions.

[0089] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A high-performance concrete antifreeze pumping agent, characterized in that, It is formulated from antifreeze polycarboxylate superplasticizer mother liquor, calcium nitrate tetrahydrate, ethylene glycol and deionized water; The antifreeze polycarboxylate superplasticizer mother liquor is prepared by polymerization of ethanolamine allyl polyethylene glycol ether, acrylic acid, acrylamide, a redox initiation system, a chain transfer agent, an alkaline regulator, and deionized water at room temperature.

2. The high-performance concrete antifreeze pumping agent according to claim 1, characterized in that, The high-performance concrete antifreeze pumping agent comprises, by weight: 50-150 parts of antifreeze polycarboxylate superplasticizer mother liquor, 300-400 parts of calcium nitrate tetrahydrate, 50-200 parts of ethylene glycol, and 400-500 parts of deionized water.

3. The high-performance concrete antifreeze pumping agent according to claim 2, characterized in that, The antifreeze polycarboxylate superplasticizer mother liquor is prepared from the following raw materials by weight: 300-400 parts of ethanolamine allyl polyethylene glycol ether, 20-40 parts of acrylic acid, 5-15 parts of acrylamide, 2-5 parts of redox initiation system, 1-2 parts of chain transfer agent, 15-30 parts of alkalinity regulator and 500-600 parts of deionized water. The number average molecular weight of the ethanolamine allyl polyethylene glycol ether is 2000-4000.

4. The high-performance concrete antifreeze pumping agent according to claim 3, characterized in that, The redox initiation system consists of a 27.5% (w / w) hydrogen peroxide solution, vitamin C, and ferrous sulfate.

5. The high-performance concrete antifreeze pumping agent according to claim 4, characterized in that, The redox initiation system comprises, by weight, 2-4 parts of a 27.5% hydrogen peroxide solution, 0.3-1.0 parts of vitamin C, and 0.01-0.02 parts of ferrous sulfate.

6. The high-performance concrete antifreeze pumping agent according to claim 5, characterized in that, The chain transfer agent is mercaptopropionic acid or mercaptoethanol; The alkalinity regulator is triethanolamine or diethanolamine.

7. The high-performance concrete antifreeze pumping agent according to claim 6, characterized in that, The high-performance concrete antifreeze pumping agent has a solid content of 40%-60%, and the dosage is 2.0%-4.0% of the total mass of cementitious materials. The applicable construction temperature range is -5℃ to -15℃.

8. A method for preparing a high-performance concrete antifreeze pumping agent, characterized in that, For preparing the high-performance concrete antifreeze pumping agent as described in any one of claims 1-7, comprising: S1. Add deionized water to the reaction vessel, then add ethanolamine allyl polyethylene glycol ether to dissolve it, and obtain the base material; S2. Prepare solutions A, B and C respectively. Solution A contains acrylic acid and acrylamide, solution B contains hydrogen peroxide solution, and solution C contains ferrous sulfate, vitamin C and chain transfer agent. S3. At room temperature, liquids A, B and C are simultaneously added dropwise to the substrate to carry out the polymerization reaction. After the addition is completed, the substrate is kept warm and matured. Then, an alkaline regulator is added to adjust the pH to obtain the antifreeze polycarboxylate superplasticizer mother liquor. S4. The antifreeze polycarboxylate superplasticizer mother liquor is mixed and diluted with deionized water and stirred. Calcium nitrate tetrahydrate is added in batches and stirred until completely dissolved. Then ethylene glycol is added and stirred evenly to obtain a high-performance concrete antifreeze pumping agent.

9. The method according to claim 8, characterized in that, In step S3, the polymerization reaction temperature is controlled to be no higher than 35°C, and an alkaline regulator is added after the dropping is completed to adjust the pH of the system to 5.0-7.0; In step S4, the high-performance concrete antifreeze pumping agent comprises, by weight: 50-150 parts of antifreeze polycarboxylate superplasticizer mother liquor, 300-400 parts of calcium nitrate tetrahydrate, 50-200 parts of ethylene glycol, and 400-500 parts of deionized water. The antifreeze polycarboxylate superplasticizer mother liquor is prepared from the following raw materials by weight: 300-400 parts of ethanolamine allyl polyethylene glycol ether, 20-40 parts of acrylic acid, 5-15 parts of acrylamide, 2-5 parts of redox initiation system, 1-2 parts of chain transfer agent, 15-30 parts of alkalinity regulator, and 500-600 parts of deionized water.

10. The method according to claim 9, characterized in that, In step S2, the hydrogen peroxide solution in solution B is a 27.5% mass concentration hydrogen peroxide solution; In step S3, the addition time for liquid A is 2.0 hours, the addition time for liquid B is 2.5 hours, the addition time for liquid C is 3.0 hours, and the heat preservation and ripening time is 1.0 hour. In step S4, the total mixing time after the addition of materials is completed shall not be less than 30 minutes.

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