Novel organic polymer concrete super plasticizer

Abstract

The invention provides a novel organic polymer concrete super plasticizer, and belongs to the technical field of concrete. The invention relates to a water-based cleaning agent, which comprises a plurality of components such as methoxy polyethylene glycol monomethacrylate, sulfoethyl acrylamide, tetrahydroxypropyl ethylenediamine, methacryloyloxyethyl sulphobetaine, acrylic acid sodium gluconate, amino modified nano silicon dioxide, ammonium persulfate, mercaptopropionic acid and the like. The superplasticizer can effectively disperse cement particles and maintain good stability, not only can flexibly adjust the setting time and early strength development of the concrete, but also can further optimize the comprehensive performance of the concrete, and meets the diversified requirements of different construction scenes and building structures on the performance of the concrete.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete, and particularly relates to a novel organic polymer concrete superplasticizer. BACKGROUND

[0002] As a basic material in the construction industry, the performance of concrete directly affects the quality and durability of construction projects. Early traditional superplasticizers, such as lignin sulfonates, can improve the workability of concrete to some extent, but have limited water-reducing rate and obvious retarding effect, making it difficult to meet the needs of modern complex construction. Although naphthalene and melamine superplasticizers have improved water-reducing rate and are widely used in conventional construction, the problem of rapid loss of slump has always restricted their use in special construction environments, such as high-temperature or long-distance concrete pouring scenarios.

[0003] In existing patents, polycarboxylate superplasticizers dominate. With high water-reducing rate and excellent slump retention performance, they have become the preferred additive for high-performance concrete. However, as the construction industry continues to refine its requirements for concrete performance, existing polycarboxylate superplasticizer patent technologies still have some limitations. Some patent technologies have complex synthesis processes and high production costs, limiting their large-scale application; some patent products are sensitive to fluctuations in the quality of raw materials, and in actual engineering, when the quality of sand and gravel and other raw materials is unstable, the performance of superplasticizers is difficult to stabilize.

[0004] To address these issues, new organic polymer concrete superplasticizer patent technologies have emerged. In terms of molecular structure design, traditional polycarboxylate superplasticizers based on acrylic acid as the main chain have been broken through. For example, new multi-copolymer monomers are used, and through special polymerization processes, organic polymers with unique comb-like structures are constructed. This structure can ensure high water-reducing rate while enhancing adaptability to different raw materials. The introduction of special functional groups, such as sulfonic acid groups and carboxyl groups, on the main chain makes the adsorption and dispersion of cement particles more stable, effectively reducing the sensitivity to fluctuations in the quality of raw materials.

[0005] However, organic polymer concrete superplasticizers also have limitations when used alone, so they need to be used in combination with multiple components. The composition and ratio of the components are key technical points for superplasticizers, directly affecting their performance. Currently, various compounded superplasticizers have different components and ratios, and their performance is uneven, with room for improvement in compatibility with other components in concrete. Therefore, it is necessary to design scientific and reasonable components and ratios to enable organic polymer superplasticizers to form chemical bonds with retarders, early strength agents, and other additives, achieving true synergistic effect. SUMMARY

[0006] The existing plasticizer has uneven performance, and the adaptability with other components in the concrete needs to be improved. A scientific and reasonable component and proportion need to be designed to make the organic polymer superplasticizer form chemical bonding with the retarder, early strength agent and other additives to realize the true synergistic effect. The application provides a new type of organic polymer concrete superplasticizer, which contains methoxy polyethylene glycol monomethacrylate, sulfoethyl acrylamide, tetrahydroxypropyl ethylenediamine, methacryloyloxyethyl sulfobetaine, sodium acrylate glucose, amino modified nano silicon dioxide, ammonium persulfate, mercapto propionic acid and other components. Through the synergistic effect of the components, the superplasticizer can effectively disperse the cement particles and maintain good stability. The superplasticizer can not only flexibly adjust the setting time and early strength development of the concrete, but also further optimize the comprehensive performance of the concrete to meet the diversified needs of different construction scenes and building structures for the performance of the concrete. The specific technical scheme is as follows. A new type of organic polymer concrete superplasticizer, characterized in that the raw materials include the following mass fractions: methoxy polyethylene glycol monomethacrylate (MPEGMA) 55-60 parts, sulfoethyl acrylamide (SEAM) 15-20 parts, tetrahydroxypropyl ethylenediamine (THPEED) 5-8 parts, methacryloyloxyethyl sulfobetaine (SBMA) 10-15 parts, sodium acrylate glucose (SAG) 3-5 parts, amino modified nano silicon dioxide 3-5 parts, ammonium persulfate (APS) 1.5-2 parts, mercapto propionic acid (MPA) 0.3-0.5 parts, and the balance is deionized water, with a solid content of 40wt%-45wt%.

[0007] In the above raw materials, the average molecular weight of the methoxy polyethylene glycol monomethacrylate is 2000.

[0008] In the above raw materials, the particle size of the amino modified nano silicon dioxide is less than 50nm.

[0009] The preparation method of the above new type of organic polymer concrete superplasticizer includes the following steps: S1, pre-dispersing nano silicon dioxide: adding the amino modified nano SiO2 into deionized water and ultrasonically dispersing to form a nano SiO2 dispersion liquid; S2, monomer mixing: adding methoxy polyethylene glycol monomethacrylate (MPEGMA), sulfoethyl acrylamide (SEAM), methacryloyloxyethyl sulfobetaine (SBMA) and sodium acrylate glucose (SAG) into a reaction kettle according to the mass fraction, stirring and mixing uniformly, and heating to 60-65℃ to obtain a mixture; S3, radical copolymerization: under stirring, tetrahydroxypropyl ethylenediamine (THPEED) is added into the mixture, then ammonium persulfate (APS) is added, then mercaptopropionic acid (MPA) is added to control the molecular weight, the reaction temperature is kept at 70-75 DEG C, the stirring is kept for 4-6 hours, and the copolymer colloid is formed.

[0010] S4, nanocomposite: the nanometer SiO2 dispersion liquid is added into the colloid, the stirring is carried out at 60-65 DEG C for 1-2 hours, and the nanometer particles are combined with the polymer chains through amino-carboxylic acid bond.

[0011] S5, post-treatment: the temperature is lowered to 30-40 DEG C, the pH is adjusted to 7.0-8.5 by using NaOH aqueous solution, and the solid content is adjusted to 40-45 wt%, and the viscous liquid is obtained.

[0012] In S1 of the above preparation method, the SiO2 is added in an amount of 6-8% of the deionized water; the ultrasonic dispersion frequency is 30-50 kHz, and the ultrasonic time is 30-50 min.

[0013] In S2 of the above preparation method, the stirring speed is 200-500 r / min. This stirring speed range can make various monomers fully mixed and uniform, meanwhile, the speed is too fast to produce too much foam or cause the material splashing, and the speed is too slow to have low mixing efficiency.

[0014] In S3 of the above preparation method, the ammonium persulfate (APS) is added in three equal parts, and each part is added for three times with an interval of 20-30 min.

[0015] In S3 of the above preparation method, the stirring speed is 300-600 r / min. This stirring speed range can ensure that the initiator, various monomers and molecular weight adjusting agent fully contact, promote the reaction to uniformly proceed, and is beneficial to heat transfer and prevent local overheating.

[0016] In S4 of the above preparation method, the stirring speed is 150-300 r / min. The lower speed can ensure that the nanometer SiO2 dispersion liquid and the colloid are fully mixed, and can avoid that the high-speed stirring destroys the combination structure between the formed polymer chains and the nanometer particles.

[0017] In S5 of the above preparation method, the concentration of the NaOH aqueous solution is 2-5 mol / L.

[0018] The novel organic polymer concrete superplasticizer has the following beneficial effects: I. Methoxy polyethylene glycol monomethacrylate (MPEGMA): The long-chain polyethylene glycol part in the molecular structure has a large steric hindrance effect. When the superplasticizer is added to the concrete system, MPEGMA is adsorbed on the surface of the cement particles, and the long chain stretches into the liquid phase, like a "umbrella" around the cement particles, preventing the mutual approach and agglomeration between the cement particles, thereby significantly improving the fluidity of the concrete. Moreover, this steric hindrance effect is relatively persistent and does not quickly weaken over time, allowing the concrete to maintain good workability for a long time. The appropriate amount of MPEGMA ensures that there is enough long-chain polyethylene glycol in the superplasticizer system to provide steric hindrance effect; this ratio can ensure good dispersion and stability effect on the cement particles, and will not cause high cost or adversely affect the performance of the concrete (such as strength development) due to excessive use.

[0019] II. Sulfoethyl acrylamide (SEAM): It contains sulfonic acid group (-SO3H) and amino group (-NH2) in its molecule. The sulfonic acid group will ionize hydrogen ion in aqueous solution, making itself carry a negative charge, while the cement particles will carry a positive charge on the surface during hydration, and through electrostatic attraction, SEAM will be firmly adsorbed on the surface of the cement particles. This adsorption not only increases the charge density of the cement particle surface, generates electrostatic repulsion between particles, thereby improving the dispersibility; at the same time, SEAM can also participate in copolymerization reaction, introducing its properties into the polymer molecular chain, further improving the overall performance of the superplasticizer. The appropriate amount of SEAM makes it fully play the role of electrostatic repulsion when cooperating with other monomers, enhancing the dispersion effect on the cement particles; at the same time, this ratio also ensures that it can appropriately participate in the construction of the polymer molecular chain in the copolymerization reaction, providing the necessary performance for the superplasticizer.

[0020] THPEED: On the one hand, it is a polyhydroxy amine compound, which can react with acidic substances in the concrete system to adjust the pH value of the system, so that the system is in an acid-base environment conducive to cement hydration and superplasticizer. On the other hand, the amino and hydroxyl groups in THPEED can form stable complexes with metal ions (such as calcium ions) in cement, which can delay the hydration process of cement, play a retarding effect, avoid rapid hardening of cement, and ensure that concrete has enough operation time during construction. In addition, in the copolymerization reaction, THPEED participates in the reaction, making the molecular chain structure of the formed polymer more regular and orderly, which is conducive to improving the performance of the superplasticizer. The appropriate amount of THPEED can effectively adjust the pH value of the system, so that it is maintained in the appropriate range, which is conducive to the hydration of cement and the performance of the superplasticizer; at the same time, this amount can also play a retarding effect just right, and cooperate with other ingredients to make the cement hydration process more reasonable, neither over-retarding affecting the construction progress, nor under-retarding leading to difficult construction operation.

[0021] SBMA: It has a unique zwitterionic structure, which carries both positive and negative charges in aqueous solution. When added to concrete, it can quickly form an adsorption layer on the surface of cement particles, with the positive charge interacting with the negative charge on the surface of cement particles, and the negative charge extending outward. This not only produces electrostatic repulsion, but also provides steric hindrance effect due to its large molecule. The two effects work together to greatly enhance the dispersion effect of cement particles, thereby improving the fluidity and stability of concrete, and making it less likely to segregate and bleed during transportation and construction. The appropriate amount of SBMA allows it to form an effective adsorption layer in the concrete system, fully exerting the electrostatic repulsion and steric hindrance effect, and working together with other ingredients to achieve good dispersion and stability effect, and improve the fluidity and stability of concrete.

[0022] SAG: The molecule contains multiple hydroxyl (-OH) and carboxyl (-COO -). Both hydroxyl and carboxyl have strong hydrophilicity and complexing ability, and they can react with calcium ions and other ions on the surface of cement particles to form chemical bonds. The formation of these chemical bonds makes SAG firmly adsorbed on the surface of cement particles, and at the same time, due to the ionization of carboxyl, the surface of cement particles has more negative charges, and electrostatic repulsion between particles is generated, thereby improving dispersibility. In addition, SAG can also interact with cement hydration products to regulate the hydration rate of cement, avoid too fast or too slow hydration, and ensure the stability of the performance of concrete. The appropriate amount of SAG enables it to form appropriate adsorption and chemical bonding on the surface of cement particles, effectively regulate the hydration rate of cement, and at the same time, synergistically improve dispersibility with other ingredients. This ratio will not affect the setting time and other properties of concrete due to excessive use, nor will it fail to achieve the expected regulation and dispersion effect due to insufficient use.

[0023] Six, amino-modified nano-silica: Nano-silica itself has a large specific surface area and high surface activity. After amino modification, the amino groups (-NH2) on its surface can chemically react with carboxyl groups (-COOH) on the polymer chain, and nano-silica is introduced into the polymer network structure through chemical bonding. In this way, not only is the polymer network structure strengthened, and the strength and durability of the superplasticizer are improved; but also nano-silica can fill the tiny pores between cement particles, play a physical filling role, make the microstructure of concrete more compact, and further improve the performance of concrete. The appropriate amount of amino-modified nano-silica enables it to form appropriate adsorption and chemical bonding on the surface of cement particles, effectively regulate the hydration rate of cement, and at the same time, synergistically improve dispersibility with other ingredients. This ratio will not affect the setting time and other properties of concrete due to excessive use, nor will it fail to achieve the expected regulation and dispersion effect due to insufficient use. It can not only ensure that nano-silica effectively strengthens the polymer network structure through chemical bonding, improves the strength and durability of the superplasticizer, but also will not cause the fluidity of concrete to decrease or increase the cost due to excessive addition, and at the same time, appropriate filling can also optimize the microstructure of concrete.

[0024] Seven, ammonium persulfate (APS): It is a free radical initiator. When heated or excited under certain conditions, ammonium persulfate will undergo decomposition reaction to produce sulfate free radicals (SO4· -active radicals. These radicals can initiate the radical copolymerization of double bonds in monomers such as MPEGMA, SEAM, etc., allowing monomer molecules to connect with each other and form long-chain polymer molecules. In this process, the decomposition rate of APS and the number of free radicals generated directly affect the rate of copolymerization and the molecular weight distribution of the polymer, having a key impact on the performance of the superplasticizer. The appropriate amount of APS can provide enough free radicals within the appropriate reaction time to initiate the copolymerization of monomers, allowing the reaction to proceed smoothly and obtain a polymer with appropriate molecular weight and structure. Too much will cause the reaction to be too violent and difficult to control; too little will cause the reaction to be slow, or even unable to completely initiate the reaction.

[0025] Eight, mercaptopropionic acid (MPA): as a chain transfer agent, the sulfhydryl group (-SH) in its molecule has high activity. In the process of radical copolymerization, when the polymer molecular chain grows to a certain extent, the sulfhydryl group of MPA can react with the growing chain radical to capture the free radical, making the original growing chain radical terminate growth, while MPA itself forms a new free radical to initiate a new chain growth reaction. In this way, MPA can effectively regulate the molecular weight and molecular chain structure of the polymer, allowing the superplasticizer to have appropriate performance. Without MPA regulation, the molecular weight of the polymer will be too high or too low, resulting in the dispersion performance, stability, etc. of the superplasticizer not meeting actual demand. The appropriate amount of MPA can well regulate the molecular weight and molecular chain structure of the polymer, ensuring that the superplasticizer has good performance. By controlling this amount, the adverse effects of too high or too low molecular weight of the polymer can be avoided, ensuring that the superplasticizer can achieve the best state in terms of dispersibility, stability, etc.

[0026] Nine, the superplasticizer of the application can effectively disperse cement particles through the synergistic effect of multiple components. The space steric hindrance of MPEGMA, electrostatic repulsion of SEAM and SBMA, and chemical bonding dispersion of SAG, etc. jointly act to make cement particles uniformly dispersed in the concrete system, significantly improving the fluidity of the concrete. This means that under the same construction conditions, less water is used to achieve the same fluidity requirement, thereby reducing the water-cement ratio and improving the strength of the concrete. The adsorption layer and network structure formed by the components can effectively prevent the agglomeration and sedimentation of cement particles, reduce the occurrence of segregation and bleeding, and ensure the performance consistency of the concrete in each construction link. The amino-modified nanosilica not only enhances the polymer network structure through chemical bonding, but also makes the microstructure of the concrete more compact and the porosity lower through physical filling. This greatly improves the impermeability of the concrete and reduces the intrusion of harmful external media (such as chloride ions and sulfate ions), thereby enhancing the durability of the concrete. DETAILED DESCRIPTION

[0027] The application will be further described below in conjunction with specific implementation examples, but the application is not limited to these examples.

[0028] Example 1 A novel organic polymer concrete superplasticizer, characterized in that it comprises the following raw materials in mass fraction: methoxy polyethylene glycol monomethacrylate (MPEGMA) 58 parts, sulfonethyl acrylamide (SEAM) 18 parts, tetrahydroxypropyl ethylenediamine (THPEED) 6.5 parts, methacryloyloxyethyl sulfobetaine (SBMA) 12 parts, sodium acrylate glucose (SAG) 4 parts, amino-modified nanosilica 4 parts, ammonium persulfate (APS) 1.8 parts, mercaptopropionic acid (MPA) 0.4 parts, and the balance is deionized water, with a solid content of 42 wt%.

[0029] The preparation method of the above-mentioned novel organic polymer concrete superplasticizer comprises the following steps: S1, pre-disperse nanosilica: add amino-modified nanosilica to deionized water, the addition amount of SiO2 is 7% of the mass of deionized water, and ultrasonic dispersion is performed at 40 kHz for 40 min to form a nanosilica dispersion liquid; S2, monomer mixing: add methoxy polyethylene glycol monomethacrylate (MPEGMA), sulfisooctyl acrylamide (SEAM), methacryloyloxyethyl sulfobetaine (SBMA), and sodium acrylate glucose (SAG) into the reaction kettle according to the mass fraction, mix uniformly under 300 r / min stirring, and heat to 62℃ to obtain a mixture; S3, radical copolymerization: under the condition of 500 r / min stirring, add tetrahydroxypropyl ethylenediamine (THPEED) into the mixture, then add ammonium persulfate (APS), divide the ammonium persulfate (APS) into 3 equal parts, add in 3 times, each time add 1 / 3, and the next time after 25 min; then add mercaptopropionic acid (MPA) to control the molecular weight, keep the reaction temperature at 72℃, and continuously stir at 500 r / min for 5 h to form a copolymer colloid.

[0030] S4, nanocomposite: add nano SiO2 dispersion liquid into the colloid, stir at 200 r / min at 62℃ for 1.5 h, so that the nanoparticles are combined with the polymer chains through amino-carboxylic acid bonds.

[0031] S5, post-processing: cool to 35℃, adjust the pH to 8.0 with 3 mol / L NaOH aqueous solution, and adjust the solid content to 42wt% to obtain a viscous liquid.

[0032] Example 2 A novel organic polymer concrete superplasticizer, characterized in that it comprises the following raw materials in mass fraction: methoxy polyethylene glycol monomethacrylate (MPEGMA) 55 parts, sulfisooctyl acrylamide (SEAM) 15 parts, tetrahydroxypropyl ethylenediamine (THPEED) 5 parts, methacryloyloxyethyl sulfobetaine (SBMA) 10 parts, sodium acrylate glucose (SAG) 3 parts, amino-modified nano-silicon dioxide 3 parts, ammonium persulfate (APS) 1.5 parts, mercaptopropionic acid (MPA) 0.3 parts, and the balance is deionized water, with a solid content of 40wt%.

[0033] The preparation method of the above-mentioned novel organic polymer concrete superplasticizer comprises the following steps: S1, pre-disperse nano-silicon dioxide: add amino-modified nano-SiO2 into deionized water, the addition amount of SiO2 is 8% of the mass of deionized water, and ultrasonic dispersion is carried out at 50 kHz for 50 min to form a nano-SiO2 dispersion liquid; S2, monomer mixing: add methoxy polyethylene glycol monomethacrylate (MPEGMA), sulfisooctyl acrylamide (SEAM), methacryloyloxyethyl sulfobetaine (SBMA), and sodium acrylate glucose (SAG) into the reaction kettle according to the mass fraction, mix uniformly under 200 r / min stirring, and heat to 60℃ to obtain a mixture; S3, radical copolymerization: under the condition of stirring at 300 r / min, tetrahydroxypropyl ethylenediamine (THPEED) is added into the mixture, then ammonium persulfate (APS) is added, the ammonium persulfate (APS) is added in three equal portions, and each portion is added for three times with an interval of 20 min; then mercaptopropionic acid (MPA) is added to control the molecular weight, the reaction temperature is kept at 70℃, and the stirring is continuously carried out at 300 r / min for 4 h to form a copolymer colloid.

[0034] S4, nanocomposite: the nano-SiO2 dispersion liquid is added into the colloid, and the stirring is carried out at 60℃ and 150 r / min for 1 h to combine the nano-particles and the polymer chains through amino-carboxylic acid bond.

[0035] S5, post-treatment: the temperature is lowered to 30℃, the pH is adjusted to 7.0 by using 5 mol / L NaOH aqueous solution, and the solid content is adjusted to 40 wt% to obtain a viscous liquid.

[0036] Example 3 A novel organic polymer concrete superplasticizer, characterized in that it comprises the following raw materials in mass fraction: methoxy polyethylene glycol monomethacrylate (MPEGMA) 60 parts, sulfoethyl acrylamide (SEAM) 20 parts, tetrahydroxypropyl ethylenediamine (THPEED) 8 parts, methacryloyloxyethyl sulfobetaine (SBMA) 15 parts, sodium acrylate glucose (SAG) 5 parts, amino-modified nano-silica 5 parts, ammonium persulfate (APS) 2 parts, mercaptopropionic acid (MPA) 0.5 parts, and the balance is deionized water, and the solid content is 45 wt%.

[0037] The preparation method of the above-mentioned novel organic polymer concrete superplasticizer comprises the following steps: S1, pre-dispersing nano-silica: the amino-modified nano-SiO2 is added into deionized water, the addition amount of SiO2 is 6% of the mass of the deionized water, and the nano-SiO2 dispersion liquid is formed by ultrasonic dispersion at 30 kHz for 30 min; S2, monomer mixing: methoxy polyethylene glycol monomethacrylate (MPEGMA), sulfoethyl acrylamide (SEAM), methacryloyloxyethyl sulfobetaine (SBMA), and sodium acrylate glucose (SAG) are added into a reaction kettle in mass fraction, and the mixture is uniformly stirred at 500 r / min, and the temperature is raised to 65℃ to obtain a mixture; S3, radical copolymerization: under the condition of stirring at 600 r / min, tetrahydroxypropyl ethylenediamine (THPEED) was added into the mixture, and then ammonium persulfate (APS) was added. The ammonium persulfate (APS) was added in three equal portions, and each portion was added for three times with an interval of 30 min. Then, mercaptopropionic acid (MPA) was added to control the molecular weight. The reaction temperature was maintained at 75℃, and the stirring was continued at 600 r / min for 6 h to form a copolymer colloid.

[0038] S4, nanocomposite: the nano-SiO2 dispersion liquid was added into the colloid, and the stirring was carried out at 65℃ and 300 r / min for 2 h to combine the nano-particles and the polymer chains through amino-carboxylic acid bond.

[0039] S5, post-treatment: the temperature was lowered to 40℃, the pH was adjusted to 8.5 by using 2 mol / L NaOH aqueous solution, and the solid content was adjusted to 45 wt% to obtain a viscous liquid.

[0040] In the above examples, the average molecular weight of methoxy polyethylene glycol monomethacrylate (MPEGMA) used was 2000, which was from Shanghai Maikelin Biochemical Technology Co., Ltd.; the particle size of amino-modified nano-silicon dioxide was less than 50 nm, which was from Shanghai Jiuxite Nano-Materials Technology Co., Ltd.

[0041] In the above examples, the sulfonethyl acrylamide (SEAM) used was from Shanghai Maikelin Biochemical Technology Co., Ltd.; the tetrahydroxypropyl ethylenediamine (THPEED) was from Guangdong Yuanfeng Chemical Reagent Co., Ltd.; the methacryloyloxyethyl sulfobetaine (SBMA) was from Wuhan Lanya Medicine and Chemical Co., Ltd.; the sodium acrylate glucose (SAG) was from Weifang Jianbao Biological Technology Co., Ltd.; the ammonium persulfate (APS) was from Qidui Chemical Industry; and the mercaptopropionic acid (MPA) was from Shandong Jinyueyuan New Material Co., Ltd.

[0042] Comparative Example 1 In the plasticizer, sulfonethyl acrylamide (SEAM) was not added; and other parameters and methods were the same as those in Example 1.

[0043] Comparative Example 2 In the plasticizer, tetrahydroxypropyl ethylenediamine (THPEED) was not added; and other parameters and methods were the same as those in Example 1.

[0044] Comparative Example 3 In the plasticizer, methacryloyloxyethyl sulfobetaine (SBMA) was not added; and other parameters and methods were the same as those in Example 1.

[0045] Comparative Example 4 In the plasticizer, sodium acrylate glucose (SAG) was not added; and other parameters and methods were the same as those in Example 1.

[0046] Comparative Example 5 In the plasticizer, the amino-modified nano-silica was replaced by nano-silica; other parameters and methods were the same as in Example 1.

[0047] Comparative Example 6 In the plasticizer, ammonium persulfate (APS) was not added; other parameters and methods were the same as in Example 1.

[0048] Comparative Example 7 In the plasticizer, mercaptopropionic acid (MPA) was not added; other parameters and methods were the same as in Example 1.

[0049] Comparative Example 8 In the plasticizer, both ammonium persulfate (APS) and mercaptopropionic acid (MPA) were not added; other parameters and methods were the same as in Example 1.

[0050] Comparative Example 9 In the plasticizer, sodium acrylate glucoronate (SAG), ammonium persulfate (APS), and mercaptopropionic acid (MPA) were not added; other parameters and methods were the same as in Example 1.

[0051] The superplasticizers prepared in each of the above examples and comparative examples were tested and detected.

[0052] 1. Water-reducing rate detection: detection was performed in accordance with GB / T 8077 “Concrete Admixture Homogeneity Test Method”.

[0053] Cement: P.O 42.5 ordinary portland cement meeting GB 175 standard was selected. Aggregate: the fineness modulus of natural river sand was controlled at 2.5, and the clay content was 2.0%; 5mm-25mm continuous gradation gravel, needle flake content 10%, clay content 0.6%. Gypsum retarder FYOK-101A (Zhengzhou City, China Central Plains Coating Technology Co., Ltd.): 0.2% of the cement dosage; GH early strength agent of Gaohe Building Materials: 3% of the cement dosage; water: clean water. Reference concrete preparation: according to the mass fraction, accurately weigh 6.2 parts of cement, 10.6 parts of sand, 16.2 parts of gravel, 1 part of water, gypsum retarder FYOK-101A, and GH early strength agent, and mix them uniformly in a forced mixer for 120s. After the mixing is completed, the base concrete is obtained, the slump of the base concrete is measured, the water amount is adjusted to make the slump reach 180mm, and the water amount W0 at this time is recorded.

[0054] Preparation of concrete with superplasticizer: the superplasticizer prepared in each example and comparative example was mixed into the concrete at 1% of the cement amount, while keeping the cement, aggregate and other ingredients unchanged. After uniform stirring under the same stirring conditions, the slump was measured again, and the water amount was adjusted to make the slump reach 180 mm, the same as the reference concrete, and the water amount W1 at this time was recorded. The calculation method: water reduction rate (%) = (W0-W1) / W0 x 100%. The test results are shown in Table 1 below.

[0055] 2. Slump retention test: according to GB / T 50080 "Standard Test Methods for Properties of Fresh Concrete" for testing.

[0056] Concrete mixing: the concrete was prepared according to the preparation method of concrete with superplasticizer in the water reduction rate test, and the initial slump was measured immediately after the preparation of the concrete. When measuring, the slump cone was placed on a solid horizontal base, the inner wall and base were moistened with a wet cloth, the concrete mixture was loaded into the slump cone in three layers, each layer was inserted and tamped 25 times with a tamping rod, and finally leveled, the height difference between the height of the cone and the highest point of the concrete test body after slumping was measured, which was the initial slump T0.

[0057] Slump measurement at different times: the concrete was loaded into a sealed container, and taken out after 30 min, 60 min and 90 min, respectively. After each time, the concrete was vibrated on a vibration table for 15 s to make the concrete mixture uniform, and then the slump T 30 , T 60 , T 90 was measured again according to the measurement method of initial slump. The calculation method: slump retention value (%) = T t / T0 x 100% (t = 30, 60, 90). The test results are shown in Table 1 below.

[0058] 3. Compressive strength ratio: according to GB 8076 "Concrete Admixtures" for testing.

[0059] Test block molding: the concrete mixture was prepared according to the above water reduction rate test method, and the concrete mixture was loaded into a test mold of 150 mm x 150 mm x 150 mm in two layers, each layer was inserted and tamped 25 times with a tamping rod, and then leveled with a spatula, and 3 test blocks were prepared for each group. Curing: the test blocks were placed in a standard curing room with a temperature of 20°C and a relative humidity of 96%. The test blocks were cured for 3d, 7d and 28d, respectively.

[0060] Compressive strength test: the test was carried out using a pressure testing machine, the test block was taken out of the curing room, the surface moisture was wiped off, and placed in the center position of the lower pressure plate of the pressure testing machine, the ball seat was adjusted to make the contact balanced. The pressure was increased until the test block was destroyed, and the destruction load F was recorded. The calculation method: compressive strength f = F / A (A is the pressure bearing area of the test block, A = 150 x 150 mm² = 22500 mm²). Compressive strength ratio (%) = f1 / f0 x 100% (f1 is the compressive strength of the superplasticizer doped concrete, f0 is the compressive strength of the basic concrete without superplasticizer). The test results are shown in Table 1 below.

[0061] Table 1 Test results

[0062] From the above results, it can be seen that the superplasticizers prepared in Examples 1 to 3 have excellent performance, can form chemical bonds with retarders, early strength agents and other additives, and achieve good synergistic effect.

[0063] Comparative Example 1 (no addition of sulfonethyl acrylamide SEAM): SEAM participates in the copolymerization reaction, and the polar groups such as amino and sulfonic acid groups in its structure help to increase the adsorption and dispersion of superplasticizer molecules on cement particles. The absence of SEAM will weaken this effect, resulting in a decrease in water reduction. SEAM has a certain effect on maintaining the adsorption stability of superplasticizer molecules on the surface of cement particles. The absence of SEAM makes the superplasticizer molecules more likely to desorb from the surface of cement particles, and the slump loss is accelerated. Due to the decrease in water reduction and slump retention, the workability and density of the concrete are affected, resulting in a decrease in compressive strength ratio.

[0064] Comparative Example 2 (no addition of tetrahydroxypropyl ethylenediamine THPEED): THPEED can play a role in adjusting the reaction rate and polymer structure in the copolymerization reaction. The absence of THPEED will affect the degree of polymerization and molecular structure of the superplasticizer molecules, and further affect their dispersion and adsorption performance on cement particles. The small decrease in the performance of the superplasticizer affects the molding quality and strength development of the concrete.

[0065] Comparative Example 3 (no addition of methacryloyloxyethyl sulfobetaine SBMA): the zwitterionic structure of SBMA makes it have good surface activity and dispersion performance. The absence of SBMA will reduce the overall dispersion ability of the superplasticizer, leading to an increase in the agglomeration of cement particles, and a decrease in water reduction and slump retention. The dispersion and workability of the concrete are deteriorated, affecting the hydration process of the cement and the density of the concrete, thereby reducing the compressive strength ratio.

[0066] Comparative Example 4 (without adding sodium acrylate gluconate SAG): The gluconate structure in SAG can chemically react with the surface of cement particles to form an adsorption layer. Without adding SAG, the adsorption effect is weakened, and the dispersion and retention performance of the superplasticizer are reduced. Changes in the performance of the superplasticizer affect the internal structure and strength development of the concrete.

[0067] Comparative Example 5 (amino-modified nano-silica is used instead of nano-silica): Amino-modified nano-silica can better enhance the performance of the superplasticizer by combining with the polymer chain through an amino-carboxylic acid bond. Ordinary nano-silica has weaker binding force with the polymer chain and has less enhancing effect on the superplasticizer than amino-modified nano-silica, resulting in a slight decrease in performance.

[0068] Comparative Example 6 (without adding ammonium persulfate APS): APS is an initiator. Without adding APS, the free radical copolymerization of monomers cannot be initiated, and a superplasticizer polymer with good performance cannot be formed, resulting in the superplasticizer losing its function and the performance of the concrete deteriorating severely.

[0069] Comparative Example 7 (without adding mercaptopropionic acid MPA): MPA is used to control the molecular weight. Without adding MPA, the molecular weight distribution of the polymer becomes wider, affecting the structure and performance of the superplasticizer molecules. However, due to the combined effects of other monomers and reaction conditions, the performance changes relatively little.

[0070] Comparative Example 8 (without adding ammonium persulfate APS and mercaptopropionic acid MPA): Without an initiator to initiate the polymerization reaction and a reagent to control the molecular weight, the superplasticizer cannot form an effective structure, and the performance of the concrete is worse than when APS is not added alone.

[0071] Comparative Example 9 (without adding sodium acrylate gluconate SAG, ammonium persulfate APS, and mercaptopropionic acid MPA): Multiple key ingredients are missing, and the superplasticizer has almost no performance. The water-reducing rate, slump retention, and compressive strength of the concrete are extremely low, and it cannot meet the actual engineering requirements.

[0072] Through the above experimental detection and analysis, the role of each component of the new organic high molecular concrete superplasticizer and the influence of different formulations on performance can be comprehensively evaluated, providing a basis for optimizing the formulation and production process of the superplasticizer.

Claims

1. A novel organic polymer concrete superplasticizer, characterized by, The raw materials include the following mass fractions: methoxy polyethylene glycol monomethacrylate 55-60 parts, sulfoethyl acrylamide 15-20 parts, tetrahydroxypropyl ethylenediamine 5-8 parts, methacryloyloxyethyl sulfobetaine 10-15 parts, sodium acrylate glucose 3-5 parts, amino-modified nanosilica 3-5 parts, ammonium persulfate 1.5-2 parts, mercaptopropionic acid 0.3-0.5 parts, and the balance is deionized water, with a solid content of 40-45 wt%.

2. A novel organic polymer concrete superplasticizer according to claim 1, characterized in that, The average molecular weight of the methoxy polyethylene glycol monomethacrylate is 2000.

3. A novel organic polymer concrete superplasticizer according to claim 1, characterized in that, The particle size of the amino-modified nanosilica is less than 50 nm.

4. A novel organic polymer concrete superplasticizer according to claim 1, characterized in that, The preparation method of the novel organic polymer concrete superplasticizer comprises the following steps: S1, pre-dispersing nanosilica: adding amino-modified nanosilica to deionized water and ultrasonically dispersing to form a nanosilica dispersion; S2, mixing monomers: adding methoxy polyethylene glycol monomethacrylate, sulfoethyl acrylamide, methacryloyloxyethyl sulfobetaine, and sodium acrylate glucose to a reaction kettle in mass fractions, stirring to mix uniformly, and heating to 60-65°C to obtain a mixture; S3, free radical copolymerization: under stirring, adding tetrahydroxypropyl ethylenediamine to the mixture, then adding ammonium persulfate, then adding mercaptopropionic acid to control the molecular weight, maintaining the reaction temperature at 70-75°C, and continuously stirring for 4-6 h to form a copolymer colloid; S4, nanocomposite: adding the nanosilica dispersion to the colloid, stirring at 60-65°C for 1-2 h to bond the nanometer particles and the polymer chains through amino-carboxylic acid bonds; S5, post-treatment: cooling to 30-40°C, adjusting the pH to 7.0-8.5 with a NaOH aqueous solution, and adjusting the solid content to 40-45 wt% to obtain a viscous liquid.

5. A novel organic polymer concrete superplasticizer according to claim 4, characterized in that, In S1, the SiO2 is added in an amount of 6-8% of the mass of the deionized water; the ultrasonic dispersion frequency is 30-50 kHz, and the ultrasonic time is 30-50 min.

6. A novel organic polymer concrete superplasticizer according to claim 4, characterized in that, In S2, the stirring speed is 200-500 r / min.

7. A novel organic polymer concrete superplasticizer according to claim 4, characterized in that, In S3, the ammonium persulfate is added in three equal portions, with each portion added at an interval of 20-30 min.

8. A novel organic polymer concrete superplasticizer according to claim 4, characterized in that, In S3, the stirring speed is 300-600 r / min.

9. A novel organic polymer concrete superplasticizer according to claim 4, characterized in that, In S4, the stirring speed is 150-300 r / min.

10. A novel organic polymer concrete superplasticizer according to claim 4, characterized in that, In S5, the concentration of the NaOH aqueous solution is 2-5 mol / L.

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