Quick-response concrete segregation treatment agent

Abstract

The invention provides a quick-response concrete segregation treatment agent, and belongs to the technical field of building materials. Comprising the following components: an acrylic acid-acrylamide-N-vinyl pyrrolidone copolymer, betaine modified sodium alginate and calcined phosphogypsum. The efficient performance is achieved through the multi-component synergistic effect and process innovation. The core component acrylic acid-acrylamide-N-vinyl pyrrolidone copolymer adsorbs free water through carboxylic acid groups, acylamino is complexed with the water reducing agent, a spatial network is formed in combination with the salt resistance of NVP, and fluidity and segregation resistance balance are optimized; glycine betaine modified sodium alginate enhances cement adsorption and a calcium cross-linked network through zwitterions in an alkaline environment, so that moisture is quickly fixed; pores in the concrete are filled with the calcined phosphogypsum, and migration channels of free water are reduced; and finally, the effect of quickly responding to segregation is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a rapid-response concrete segregation treatment agent. Background Art

[0002] Concrete segregation refers to the phenomenon that the concrete mixture separates due to insufficient cohesion among its components (such as coarse aggregates, mortar, etc.), manifested as the sinking of aggregates and the floating of the paste, which in turn causes problems such as uneven structure, reduced strength, and surface defects. The main causes include improper materials and mix ratios (such as unreasonable aggregate gradation, too high water-binder ratio, excessive admixtures) and non-standard construction operations (such as insufficient mixing, too large pouring drop, and random water addition on site).

[0003] Preventing segregation requires starting from two aspects: optimizing the mix ratio and strictly managing construction. By adjusting the sand ratio, controlling the particle size distribution of fine aggregates, reasonably using admixtures, and slow-release water reducers to improve the cohesion of concrete; at the same time, strengthening the quality control of aggregates, standardizing the mixing and transportation process, and optimizing the pouring process.

[0004] A concrete segregation treatment agent is an admixture used to improve the stability of the concrete mixture, which prevents the segregation phenomenon caused by the separation of components (such as the sinking of aggregates and the floating of the paste) during transportation and pouring through physical or chemical actions. Its core goal is to maintain the homogeneity of concrete and avoid problems such as uneven strength and surface defects caused by segregation. Summary of the Invention

[0005] The purpose of the present invention is to provide a segregation treatment agent with rapid-response characteristics and quick anti-segregation effect. The specific solutions are as follows:

[0006] A rapid-response concrete segregation treatment agent contains the following components by mass:

[0007] Acrylic acid-acrylamide-N-vinylpyrrolidone copolymer 100

[0008] Betaine-modified sodium alginate 30 - 40

[0009] Calcined phosphogypsum 10 - 20

[0010] The acrylic acid-acrylamide-N-vinylpyrrolidone copolymer is a linear polymer obtained by mixing acrylic acid, acrylamide, and N-vinylpyrrolidone and then carrying out free radical polymerization under the action of a free radical initiator;

[0011] The betaine-modified sodium alginate is a linear zwitterionic polymer formed by the amidation reaction of sodium alginate and betaine derivatives;

[0012] The molar ratio of the acrylic acid, acrylamide, and N-vinylpyrrolidone is 1:2 - 3:0.2 - 0.5;

[0013] The molar ratio of the sodium alginate and the betaine derivative is 1:0.8 - 1.4.

[0014] Preferably, the G / M ratio of the sodium alginate ≤ 1.

[0015] Preferably, the betaine derivative is alkylamide betaine.

[0016] Preferably, the preparation method of the betaine-modified sodium alginate is as follows:

[0017] Dissolve the sodium alginate in water and adjust the pH to 5 - 6; then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide and stir to mix; then add the betaine derivative and adjust the pH to 7 - 8 and react for at least 24 h; then dialyze the unreacted substances and then dry.

[0018] The molar ratio of the sodium alginate, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and N-hydroxysuccinimide is 1:1.2 - 1.5:1.2 - 1.5.

[0019] Preferably, the preparation method of the acrylic acid-acrylamide-N-vinylpyrrolidone copolymer is as follows:

[0020] Dissolve the acrylic acid, acrylamide, and N-vinylpyrrolidone in a solvent and adjust the pH of the solution to 6 - 7;

[0021] In an inert gas environment, add a radical initiator of 0.1 - 0.3 wt% of the mass of the polymerization monomers to the solution; raise the temperature to 65 ± 5 °C to initiate polymerization;

[0022] Then add a chain transfer agent of 0.02 - 0.05 wt% of the mass of the polymerization monomers; raise the temperature to 70 ± 2 °C and react for 3 - 4 h;

[0023] After the reaction time ends, terminate the reaction, wash the reactants, and then dry;

[0024] The concentration of the polymerization monomers in the solution ≤ 40 wt%.

[0025] Preferably, the calcined phosphogypsum is obtained by calcining the phosphogypsum and then ball-milling it;

[0026] The calcination is to calcine the phosphogypsum at 350 - 400 °C for at least 30 min; then raise the temperature to at least 800 °C and calcine for at least 20 min; after cooling, ball-mill it to D90 ≤ 1 μm.

[0027] Through the compounding of a multi-branched linear copolymer and an inorganic filler, the present invention realizes the rapid response of concrete anti-segregation through the triple mechanisms of water reducer complexation, water retention, and setting retardation; specifically divided into:

[0028] 1: In the acrylic acid (AAC)-acrylamide (AAm)-N-vinylpyrrolidone copolymer (NVP), the carboxylic acid group of acrylic acid adsorbs free water through hydrogen bonds, reducing the bleeding rate of concrete; the ionized COO⁻ can bind to Ca²⁺ on the surface of cement particles to adjust the rheology of the paste. The amide group of acrylamide binds to the ether bond in the polycarboxylate water reducer through a coordination bond, inhibiting the segregation caused by excessive addition of the water reducer. It forms an intermolecular hydrogen bond with NVP to enhance the structural stability of the polymer at high temperatures. The polar pyrrolidone group of N-vinylpyrrolidone (NVP) improves the dispersibility of cement particles through a steric hindrance effect; and the hydrophilic-hydrophobic amphiphilicity of N-vinylpyrrolidone can improve the dispersion stability of the copolymer and enhance the temperature and salt resistance in concrete.

[0029] In order to prevent the formation of a three-dimensional network during copolymerization and control the molecular weight of the polymer, the present invention does not add a cross-linking agent during preparation but only adds a radical initiator to initiate polymerization; and a chain transfer agent is added to limit the growth of the polymer chain, thereby reducing the molecular weight and reducing the molecular weight dispersity; increasing the water absorption rate of the copolymer and reducing the viscosity.

[0030] Compared with adding separate polyacrylic acid, polyacrylamide, and polyvinylpyrrolidone; the ternary copolymer of the present invention combines the carboxylic acid group of acrylic acid (adsorbing free water), the flocculation effect of acrylamide (complexing excessive water reducer), and the hydrophobic association ability of NVP (enhancing intermolecular physical cross-linking). This synergistic effect can simultaneously solve the segregation problems caused by excessive addition of the water reducer, changes in the mud content of sand and gravel, or excessive water use. In contrast, single polyacrylic acid only inhibits segregation through water retention, but may affect fluidity due to high viscosity; while the copolymer adjusts the molecular chain flexibility of polyacrylamide (PAM) and polyvinylpyrrolidone (PVP), reducing both free water and avoiding excessive thickening.

[0031] 2. The betaine-modified sodium alginate added in the present invention; through chemical cross-linking, the carboxylic acid group of sodium alginate and the quaternary ammonium group of betaine form a stable network structure. The water retention ability of sodium alginate and the dispersion and anti-cohesion effect of betaine (reducing the viscosity of the paste through zwitterionic characteristics) are combined to simultaneously inhibit the segregation caused by excessive addition of the water reducer and excessive water use. The zwitterionic characteristics of the copolymer make it more easily dispersed in the concrete slurry, avoiding the process limitation that unmodified sodium alginate needs to be dissolved at high temperature; and when traditional betaine is used alone, it may prolong the setting time due to residual setting retardation components, while the copolymer reduces the setting retardation effect of free betaine through chemical bonding.

[0032] Sodium alginate is a linear block copolymer formed by connecting β-D-mannuronic acid (M unit) and α-L-guluronic acid (G unit) through 1,4-glycosidic bonds; the sugar ring structure of the G unit is more compact, with a high degree of carboxyl exposure, and it is easy to crosslink with divalent cations (such as Ca²⁺) to form a rigid gel. The sugar ring structure of the M unit is more flexible, with less steric hindrance in the side chain, and the molecular chain is more likely to stretch in aqueous solution, forming a more open network structure. This property is beneficial to the penetration and adsorption of water molecules; therefore, the present invention defines that the G / M ratio of sodium alginate ≤ 1; ensuring higher water absorption.

[0033] 3. In addition to containing harmful components such as acidic substances and heavy metals, phosphogypsum solid waste also contains water-soluble impurities such as fluorine and phosphorus, which will seriously limit the industrial application of phosphogypsum; therefore, phosphogypsum needs to be treated before application. The present invention adopts the method of calcining at both ends; initially removing crystal water at 350-400 °C and calcining phosphogypsum at a high temperature of about 800 °C can convert eutectic phosphorus into inert insoluble pyrophosphate, and at the same time, organic matter evaporates and is removed; realizing the harmless treatment of phosphogypsum, and then ball milling to D90 ≤ 1 μm can improve the dispersibility.

[0034] Calcium sulfate in phosphogypsum reacts with tricalcium aluminate in cement to form ettringite. This needle-like crystal can fill the internal pores of concrete, reduce the migration channels of free water, and thus inhibit the separation of the paste and aggregate. The hydration reaction of phosphogypsum is accompanied by a slight volume expansion, which can compensate for the drying shrinkage of concrete, reduce the internal stress concentration and crack propagation caused by shrinkage, and maintain the structural integrity.

[0035] The present invention realizes high performance through the synergistic action of multiple components and process innovation. Its core component, acrylic acid-acrylamide-N-vinylpyrrolidone copolymer, adsorbs free water through carboxyl groups, complexes water reducers through amide groups, and forms a spatial network in combination with the salt resistance of NVP to optimize the balance of fluidity and anti-segregation; betaine-modified sodium alginate enhances cement adsorption and calcium crosslinking network through zwitterions in an alkaline environment to quickly fix water; calcined phosphogypsum fills the internal pores of concrete, reducing the migration channels of free water. The controlled radical polymerization is adopted in the preparation method to ensure a linear structure, and the grafting process is combined to achieve high reaction efficiency. Finally, the effect of quickly responding to segregation is achieved. Detailed implementation mode

[0036] The technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0038] In the description of the present invention, the term "for example" is used to mean "serving as an example, illustration, or explanation". Any embodiment described as "for example" in the present invention is not necessarily to be construed as more preferred or advantageous than other embodiments. The following description is given to enable any person skilled in the art to make and use the present invention. In the following description, details are set forth for purposes of explanation. It should be understood that those of ordinary skill in the art can recognize that the present invention can be practiced without these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of the present invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0039] Unless otherwise specified, the experimental methods used in the specific embodiments are all conventional methods, and the materials, reagents, etc. used, unless otherwise specified, can all be obtained from commercial sources.

[0040] In the present invention, unless otherwise specified, "%" represents mass percentage; the raw materials, reagents, etc. used are all conventional commercially available products.

[0041] The sodium alginate used in the present invention is sodium alginate extracted from Sargassum sargassum, and the proportion of M units in the natural molecular chain exceeds 50%.

[0042] The radical initiator used in the present invention is azobisisobutyronitrile (AIBN).

[0043] The chain transfer agent used in the present invention is thioglycolic acid.

[0044] The betaine derivative used in the present invention is alkylamide betaine, specifically cocamidopropyl betaine.

[0045] The calcined phosphogypsum used in the present invention is treated by the following method:

[0046] The phosphogypsum is calcined at 350 - 400 °C for 30 min; then the temperature is raised to 800 °C and calcined at this temperature for 20 min; after cooling, it is ball-milled to D90 ≤ 1 μm.

[0047] Example 1

[0048] Preparation of concrete segregation treatment agent, including the following steps:

[0049] S1: Preparation of acrylic acid - acrylamide - N - vinylpyrrolidone copolymer

[0050] Dissolve acrylic acid, acrylamide, and N - vinylpyrrolidone in water, and add NaOH to adjust the pH of the solution to 6; and introduce nitrogen into the solution for 30 min to remove oxygen;

[0051] The molar ratio of acrylic acid, acrylamide, and N - vinylpyrrolidone is 1:2:0.2;

[0052] The concentration of the polymerization monomer in the solution is 40 wt%.

[0053] Introduce nitrogen into the reaction kettle, and add 0.1 wt% of azobisisobutyronitrile based on the mass of the polymerization monomer to the solution; heat up to 70 °C to initiate polymerization,

[0054] Then add 0.02 wt% of mercaptoacetic acid based on the mass of the polymerization monomer; heat up to 70 °C and react for 3 h;

[0055] After the reaction time reaches, rapidly cool down to terminate the reaction. Wash the reactant with water multiple times, and then dry;

[0056] Obtain acrylic acid - acrylamide - N - vinylpyrrolidone copolymer.

[0057] S2: Preparation of betaine - modified sodium alginate

[0058] Dissolve sodium alginate in water, and adjust the pH to 5 with dilute hydrochloric acid; then add 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide and N - hydroxysuccinimide and stir and mix; then add coconut oil amide propyl betaine and adjust the pH to 7 with NaOH and react for at least 24 h; then dialyze the unreacted substances with a cellulose membrane, and then dry;

[0059] The molar ratio of sodium alginate, coconut oil amide propyl betaine, 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide, and N - hydroxysuccinimide is 1:0.8:1.2:1.2.

[0060] Obtain the preparation of betaine - modified sodium alginate.

[0061] S3: Mixing

[0062] Take the aforementioned acrylic acid - acrylamide - N - vinylpyrrolidone copolymer, betaine - modified sodium alginate, and calcined phosphogypsum and mix them in a mass ratio of 1:0.3:0.1; then seal and store for later use.

[0063] Example 2

[0064] Preparation of concrete segregation treatment agent, including the following steps:

[0065] S1: Preparation of acrylic acid - acrylamide - N - vinylpyrrolidone copolymer

[0066] Dissolve acrylic acid, acrylamide, and N - vinylpyrrolidone in water, and add NaOH to adjust the pH of the solution to 7; and introduce nitrogen into the solution for 30 min to remove oxygen;

[0067] The molar ratio of acrylic acid, acrylamide, and N - vinylpyrrolidone is 1:2.5:0.4;

[0068] The concentration of the polymerization monomer in the solution is 40 wt%.

[0069] Introduce nitrogen into the reaction kettle, add 0.2 wt% of azobisisobutyronitrile based on the mass of the polymerization monomer to the solution; heat up to 65 °C to initiate polymerization,

[0070] Then add 0.02 wt% of mercaptoacetic acid based on the mass of the polymerization monomer; heat up to 68 °C and react for 4 h;

[0071] After the reaction time is reached, rapidly cool down to terminate the reaction, wash the reactant with water multiple times, and then dry;

[0072] Obtain acrylic acid - acrylamide - N - vinylpyrrolidone copolymer.

[0073] S2: Preparation of betaine - modified sodium alginate

[0074] Dissolve sodium alginate in water, adjust the pH to 5 with dilute hydrochloric acid; then add 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide and N - hydroxysuccinimide and stir to mix; then add coconut amide propyl betaine and adjust the pH to 8 with NaOH and react for at least 24 h; then dialyze the unreacted substances with a cellulose membrane and then dry;

[0075] The molar ratio of sodium alginate, coconut amide propyl betaine, 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide, and N - hydroxysuccinimide is 1:1.2:1.4:1.4.

[0076] Obtain the preparation of betaine - modified sodium alginate.

[0077] S3: Mixing

[0078] Take the aforementioned acrylic acid - acrylamide - N - vinylpyrrolidone copolymer, betaine - modified sodium alginate, and calcined phosphogypsum and mix them in a mass ratio of 1:0.35:0.15; then seal and store for later use.

[0079] Example 3

[0080] Preparation of concrete segregation treatment agent, including the following steps:

[0081] S1: Preparation of acrylic acid - acrylamide - N - vinylpyrrolidone copolymer

[0082] Dissolve acrylic acid, acrylamide, and N - vinylpyrrolidone in water, and add NaOH to adjust the pH of the solution to 7; then introduce nitrogen into the solution for 30 min to remove oxygen;

[0083] The molar ratio of acrylic acid, acrylamide, and N - vinylpyrrolidone is 1:3:0.5;

[0084] The concentration of the polymerization monomer in the solution is 40 wt%.

[0085] Introduce nitrogen into the reaction kettle, and add 0.3 wt% of azobisisobutyronitrile based on the mass of the polymerization monomer to the solution; heat up to 60 °C to initiate polymerization,

[0086] Then add 0.02 wt% of mercaptoacetic acid based on the mass of the polymerization monomer; heat up to 72 °C and react for 3 h;

[0087] After the reaction time reaches, rapidly cool down to terminate the reaction. Wash the reactant with water multiple times, and then dry;

[0088] Obtain acrylic acid - acrylamide - N - vinylpyrrolidone copolymer.

[0089] S2: Preparation of betaine - modified sodium alginate

[0090] Dissolve sodium alginate in water, and adjust the pH to 6 with dilute hydrochloric acid; then add 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide and N - hydroxysuccinimide and stir and mix; then add coconut oil amide propyl betaine and adjust the pH to 8 with NaOH and react for at least 24 h; then dialyze the unreacted substances with a cellulose membrane, and then dry;

[0091] The molar ratio of sodium alginate, coconut oil amide propyl betaine, 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide, and N - hydroxysuccinimide is 1:1.4:1.5:1.5.

[0092] Obtain the preparation of betaine - modified sodium alginate.

[0093] S3: Mixing

[0094] Take the aforementioned acrylic acid - acrylamide - N - vinylpyrrolidone copolymer, betaine - modified sodium alginate, and calcined phosphogypsum and mix them in a mass ratio of 1:0.4:0.2; then seal and store for later use.

[0095] Example 4

[0096] The preparation of the concrete segregation treatment agent includes the following steps:

[0097] S1: Preparation of acrylic acid - acrylamide copolymer

[0098] Dissolve acrylic acid and acrylamide in water, and add NaOH to adjust the pH of the solution to 6; and introduce nitrogen into the solution for 30 minutes to remove oxygen;

[0099] The molar ratio of acrylic acid to acrylamide is 1:2;

[0100] The concentration of the polymerization monomer in the solution is 40 wt%.

[0101] Introduce nitrogen into the reaction kettle, add 0.1 wt% of azobisisobutyronitrile based on the mass of the polymerization monomer to the solution; heat up to 70 °C to initiate polymerization,

[0102] Then add 0.02 wt% of mercaptoacetic acid based on the mass of the polymerization monomer; heat up to 70 °C and react for 3 h;

[0103] After the reaction time reaches, rapidly cool down to terminate the reaction, wash the reactant with water multiple times, and then dry;

[0104] Obtain acrylic acid - acrylamide - N - vinylpyrrolidone copolymer.

[0105] S2: Preparation of betaine - modified sodium alginate

[0106] Dissolve sodium alginate in water, adjust the pH to 5 with dilute hydrochloric acid; then add 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide and N - hydroxysuccinimide and stir and mix; then add coconut oil amide propyl betaine and adjust the pH to 7 with NaOH and react for at least 24 h; then dialyze the unreacted substances with a cellulose membrane and then dry;

[0107] The molar ratio of sodium alginate, coconut oil amide propyl betaine, 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide, and N - hydroxysuccinimide is 1:0.8:1.2:1.2.

[0108] Obtain the preparation of betaine - modified sodium alginate.

[0109] S3: Mixing

[0110] Take the aforementioned acrylic acid - acrylamide copolymer, betaine - modified sodium alginate, and calcined phosphogypsum and mix them in a mass ratio of 1:0.3:0.1; then seal and store for later use.

[0111] Example 5

[0112] Preparation of concrete segregation treatment agent, including the following steps:

[0113] S1: Preparation of mixed polymer

[0114] Weigh polyacrylic acid, polyacrylamide and polyvinylpyrrolidone in a molar ratio of 1:2:0.2 and mix them; obtain the mixed polymer.

[0115] S2: Preparation of betaine-modified sodium alginate

[0116] Dissolve sodium alginate in water and adjust the pH to 5 with dilute hydrochloric acid; then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide and stir to mix; then add cocamidopropyl betaine and adjust the pH to 7 with NaOH and react for at least 24 h; then dialyze the unreacted substances with a cellulose membrane and then dry;

[0117] The molar ratio of sodium alginate, cocamidopropyl betaine, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and N-hydroxysuccinimide is 1:0.8:1.2:1.2.

[0118] Obtain the preparation of betaine-modified sodium alginate.

[0119] S3: Mixing

[0120] Take the mixed polymer, betaine-modified sodium alginate and calcined phosphogypsum and mix them in a mass ratio of 1:0.3:0.1; then seal and store for later use.

[0121] Example 6

[0122] Preparation of concrete segregation treatment agent, including the following steps:

[0123] S1: Preparation of mixed polymer

[0124] Weigh polyacrylic acid and polyacrylamide in a molar ratio of 1:2 and mix them; obtain the mixed polymer.

[0125] S2: Preparation of betaine-modified sodium alginate

[0126] Dissolve sodium alginate in water and adjust the pH to 5 with dilute hydrochloric acid; then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide and stir to mix; then add cocamidopropyl betaine and adjust the pH to 7 with NaOH and react for at least 24 h; then dialyze the unreacted substances with a cellulose membrane and then dry;

[0127] The molar ratio of sodium alginate, cocamidopropyl betaine, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and N-hydroxysuccinimide is 1:0.8:1.2:1.2.

[0128] Preparation of betaine-modified sodium alginate

[0129] S3: Mixing

[0130] Take the mixed polymer, betaine-modified sodium alginate and calcined phosphogypsum and mix them in a mass ratio of 1:0.3:0.1; then seal and store for later use.

[0131] Example 7

[0132] Preparation of concrete segregation treatment agent, including the following steps:

[0133] S1: Preparation of acrylic acid-acrylamide-N-vinylpyrrolidone copolymer

[0134] Dissolve acrylic acid, acrylamide, and N-vinylpyrrolidone in water, and add NaOH to adjust the pH to 6 solution; and introduce nitrogen into the solution for 30 min to remove oxygen;

[0135] The molar ratio of the acrylic acid, acrylamide, and N-vinylpyrrolidone is 1:2:0.2;

[0136] The concentration of the polymerization monomer in the solution is 40 wt%.

[0137] Introduce nitrogen into the reaction kettle, add 0.1 wt% of azobisisobutyronitrile based on the mass of the polymerization monomer to the solution; heat up to 70 °C to initiate polymerization,

[0138] Then add 0.02 wt% of mercaptoacetic acid based on the mass of the polymerization monomer; heat up to 70 °C and react for 3 h;

[0139] After the reaction time reaches, rapidly cool down to terminate the reaction, wash the reactant with water multiple times, and then dry;

[0140] Obtain acrylic acid-acrylamide-N-vinylpyrrolidone copolymer.

[0141] S2: Preparation of betaine sodium alginate mixture

[0142] Weigh sodium alginate and cocamidopropyl betaine in a molar ratio of 1:0.8 and mix them; obtain betaine sodium alginate mixture.

[0143] S3: Mixing

[0144] Take the aforementioned acrylic acid-acrylamide-N-vinylpyrrolidone copolymer, betaine sodium alginate mixture and calcined phosphogypsum and mix them in a mass ratio of 1:0.3:0.1; then seal and store for later use.

[0145] Example 8

[0146] Preparation of concrete segregation treatment agent, including the following steps:

[0147] S1: Preparation of acrylic acid - acrylamide - N - vinylpyrrolidone copolymer

[0148] Dissolve acrylic acid, acrylamide, and N - vinylpyrrolidone in water, and add NaOH to adjust the pH to 6 solution; and introduce nitrogen into the solution for 30 min to remove oxygen;

[0149] The molar ratio of acrylic acid, acrylamide, and N - vinylpyrrolidone is 1:2:0.2;

[0150] The concentration of polymerization monomers in the solution is 40 wt%.

[0151] Introduce nitrogen into the reaction kettle, add 0.1 wt% of azobisisobutyronitrile based on the mass of the polymerization monomers to the solution; heat up to 70 °C to initiate polymerization,

[0152] Then add 0.02 wt% of mercaptoacetic acid based on the mass of the polymerization monomers; heat up to 70 °C and react for 3 h;

[0153] After the reaction time reaches, rapidly cool down to terminate the reaction, wash the reactants with water multiple times, and then dry;

[0154] Obtain acrylic acid - acrylamide - N - vinylpyrrolidone copolymer.

[0155] S2: Mixing

[0156] Take the aforementioned acrylic acid - acrylamide - N - vinylpyrrolidone copolymer, sodium alginate, and calcined phosphogypsum and mix them in a mass ratio of 1:0.3:0.1; then seal and store for later use.

[0157] Example 9

[0158] Preparation of concrete segregation treatment agent, including the following steps:

[0159] S1: Preparation of acrylic acid - acrylamide - N - vinylpyrrolidone copolymer

[0160] Dissolve acrylic acid, acrylamide, and N - vinylpyrrolidone in water, and add NaOH to adjust the pH to 6 solution; and introduce nitrogen into the solution for 30 min to remove oxygen;

[0161] The molar ratio of acrylic acid, acrylamide, and N - vinylpyrrolidone is 1:2:0.2;

[0162] The concentration of polymerization monomers in the solution is 40 wt%.

[0163] Introduce nitrogen into the reaction kettle, and add azobisisobutyronitrile at 0.1 wt% of the mass of the polymerization monomer to the solution; heat up to 70 °C to initiate polymerization,

[0164] then add mercaptoacetic acid at 0.02 wt% of the mass of the polymerization monomer; heat up to 70 °C and react for 3 h;

[0165] After the reaction time is reached, rapidly cool down to terminate the reaction. After washing the reactants with water multiple times, then dry;

[0166] Obtain acrylic acid-acrylamide-N-vinylpyrrolidone copolymer.

[0167] S2: Preparation of betaine-modified sodium alginate

[0168] Dissolve sodium alginate in water, and adjust the pH to 5 with dilute hydrochloric acid; then add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide and stir to mix; then add coconut amide propyl betaine and adjust the pH to 7 with NaOH and react for at least 24 h; then dialyze the unreacted substances with a cellulose membrane, and then dry;

[0169] The molar ratio of sodium alginate, coconut amide propyl betaine, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and N-hydroxysuccinimide is 1:0.8:1.2:1.2.

[0170] Obtain the preparation of betaine-modified sodium alginate.

[0171] S3: Mixing

[0172] Take the acrylic acid-acrylamide-N-vinylpyrrolidone copolymer, betaine-modified sodium alginate prepared above and mix them in a ratio of 1:0.1 by mass; then seal and store for later use.

[0173] Perform performance tests on the foregoing examples, and the test methods are as follows:

[0174] Mix 300 kg of cement, 750 kg of natural sand, 160 kg of water, 800 kg of natural gravel, and 6 kg of water reducer to obtain concrete.

[0175] Weigh 1.0 kg of the concrete segregation inhibitor prepared in the corresponding example and mix it with the above concrete. After standing, obtain the concrete to be tested; test the slump, compressive strength, and anti-segregation onset time of the concrete to be tested, and the results are shown in Table 1.

[0176] The slump of the concrete is tested in accordance with the "Standard Test Method for Properties of Ordinary Concrete Mixtures" (GB / T 50080-2016)

[0177] The compressive strength was tested in accordance with the "Standard Test Method for Physical and Mechanical Properties of Concrete" (GB / T 50081-2019).

[0178] Table 1

[0179] Group Slump / Spread (mm) Compressive Strength (Mpa) Anti-segregation Onset Time (min) Example 1 215 48.8 4 Example 2 205 49.3 3 Example 3 200 51.4 3 Example 4 240 46.4 4 Example 5 230 45.5 10 Example 6 240 43.2 8 Example 7 230 46.2 9 Example 8 245 42.3 11 Example 9 225 47.7 6 Not Added 280 31.6 / Commercially Available RH420 220 40.1 40

[0180] As can be seen from the results in Table 1, the concrete segregation treatment agents prepared in Examples 1-3 of the present invention can quickly respond to the segregation phenomenon of concrete; and have no negative impact on the compressive strength of concrete.

[0181] The concrete segregation treatment agent prepared in Example 4 lacks N-vinylpyrrolidone;

[0182] The concrete segregation treatment agent prepared in Example 5 uses polyacrylic acid, polyacrylamide, and polyvinylpyrrolidone to replace the acrylic acid-acrylamide-N-vinylpyrrolidone copolymer.

[0183] The concrete segregation treatment agent prepared in Example 6 uses polyacrylic acid and polyacrylamide to replace the acrylic acid-acrylamide-N-vinylpyrrolidone copolymer.

[0184] The concrete segregation treatment agent prepared in Example 7 uses sodium alginate and cocamidopropyl betaine to replace betaine-modified sodium alginate.

[0185] The concrete segregation treatment agent prepared in Example 8 uses sodium alginate to replace betaine-modified sodium alginate.

[0186] The concrete segregation treatment agent prepared in Example 9 does not add calcined phosphogypsum.

[0187] As mentioned above, Example 4 did not introduce N-vinylpyrrolidone and only synthesized acrylic acid-acrylamide copolymer; the missing pyrrolidone group will reduce the complexing ability of the copolymer to the polycarboxylate superplasticizer.

[0188] Example 5: Directly uses physically mixed polyacrylic acid, polyacrylamide, and polyvinylpyrrolidone; the physically mixed polymers cannot form a uniform molecular network structure and have a weak complexing effect on the superplasticizer.

[0189] Example 6 also lacks the pyrrolidone group on the basis of Example 5, resulting in a further decline in performance.

[0190] In Example 7, sodium alginate was not chemically modified with betaine, and only sodium alginate and cocamidopropyl betaine were physically mixed. Chemical modification can graft betaine groups onto the sodium alginate molecular chain to form an amphoteric ion structure and enhance the adsorption ability of free water. Physically mixed betaine is easily migrated with water, and the water retention effect is unstable, resulting in the inability to effectively bind free water in the segregated concrete.

[0191] In Example 8, the betaine modification step was completely omitted, and unmodified sodium alginate was directly used. The unmodified sodium alginate has weak water retention and lacks the hydrophobic-hydrophilic balance effect of betaine, making it difficult to adsorb excessive moisture.

[0192] In Example 9, calcined phosphogypsum was missing, and the effect of filling the internal pores of concrete and reducing the migration of free water was lacking.

[0193] The above detailed description is a specific description of one of the feasible embodiments of the present invention, and this embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or change without departing from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A quick response concrete segregation treatment agent, characterized in that: Contains the following ingredients by mass: Acrylic acid-acrylamide-N-vinyl pyrrolidone copolymer 100 Betaine modified sodium alginate 30-40 Calcined phosphogypsum 10-20 The acrylic acid-acrylamide-N-vinyl pyrrolidone copolymer is a linear polymer obtained by mixing acrylic acid, acrylamide and N-vinyl pyrrolidone and then subjecting the mixture to free radical polymerization under the action of a free radical initiator; The betaine-modified sodium alginate is a linear zwitterionic polymer formed by amidation reaction of sodium alginate and a betaine derivative; The molar ratio of acrylic acid, acrylamide and N-vinyl pyrrolidone is 1:2-3:0.2-0.5; The molar ratio of the sodium alginate to the betaine derivative is 1:0.8-1.

4.

2. The rapid response concrete segregation treatment agent according to claim 1, characterized in that: The G / M ratio of the sodium alginate is ≤1.

3. The rapid response concrete segregation treatment agent according to claim 1, characterized in that: The betaine derivative is alkylamide betaine.

4. The rapid response concrete segregation treatment agent according to claim 1, characterized in that: The preparation method of the betaine-modified sodium alginate is as follows: dissolving sodium alginate in water and adjusting the pH to 5-6; then adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide and stirring and mixing; then adding a betaine derivative and adjusting the pH to 7-8 to react for at least 24 hours; then dialyzing the unreacted product and then drying.

5. The rapid response concrete segregation treatment agent according to claim 4, characterized in that: The molar ratio of the sodium alginate to 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide is 1:1.2-1.5:1.2-1.

5.

6. The rapid response concrete segregation treatment agent according to claim 1, characterized in that: The preparation method of the acrylic acid-acrylamide-N-vinyl pyrrolidone copolymer is as follows: dissolving acrylic acid, acrylamide, and N-vinyl pyrrolidone in a solvent, and adjusting the pH of the solution to 6-7; In an inert gas environment, 0.1-0.3wt% of the free radical initiator based on the mass of the polymerization monomer is added to the solution; the temperature is raised to 65±5°C to initiate polymerization; Then add 0.02-0.05wt% of the mass of the polymerization monomer as chain transfer agent; raise the temperature to 70±2℃ and react for 3-4h; After the reaction time is over, the reaction is terminated, and the reactant is washed and then dried.

7. The rapid response concrete segregation treatment agent according to claim 6, characterized in that: The concentration of the polymerizable monomers in the solution is ≤40wt%.

8. The rapid response concrete segregation treatment agent according to claim 1, characterized in that: The calcined phosphogypsum is obtained by calcining the phosphogypsum and then ball milling it; The calcination comprises calcining the phosphogypsum at 350-400° C. for at least 30 minutes; then heating the temperature to at least 800° C. for at least 20 minutes; and then cooling the temperature and ball milling the phosphogypsum to a D90 of ≤1 μm.