CN114075316A

CN114075316A - Superplasticizer for ultrahigh-performance concrete and preparation method thereof

Info

Publication number: CN114075316A
Application number: CN202010850544.2A
Authority: CN
Inventors: 舒鑫; 冉千平; 杨勇; 张倩倩; 王秀梅; 陆加越; 郭飞; 马建峰
Original assignee: Sobute New Materials Co Ltd; Bote Building Materials Tianjin Co Ltd; Bote New Materials Taizhou Jiangyan Co Ltd; Nanjing Bote New Materials Co Ltd
Current assignee: Sobute New Materials Co Ltd; Bote Building Materials Tianjin Co Ltd; Bote New Materials Taizhou Jiangyan Co Ltd; Nanjing Bote New Materials Co Ltd
Priority date: 2020-08-21
Filing date: 2020-08-21
Publication date: 2022-02-22

Abstract

The invention provides a superplasticizer for ultra-high performance concrete and a preparation method thereof. The superplasticizer for the ultra-high performance concreteFrom branched functional groups R₂₁And a polymer chain segment of the water reducing agent; each branched functional group R₂₁3-4 water reducing agent polymer chain segments are linked; the branched functional group R₂₁The structure of (1) comprises an alkylamino phosphoric acid functional group which is connected with an ethyl group or an isopropyl group through a saturated alkyl group or a phenyl group containing 1-9 carbon atoms, wherein two carbon atoms in the ethyl group and the isopropyl group and P are branched sites, and are connected with a polymer chain segment of the water reducing agent through a single bond. The superplasticizer comprehensively enhances the adhesion capability, thereby effectively reducing the viscosity of slurry, and in addition, compared with the common commercial superplasticizer, the superplasticizer has lower solution viscosity and weaker bridging effect under the condition of the same solution concentration, and compared with the prior art, the superplasticizer can obviously improve the fluidity of ultrahigh-performance concrete and reduce the viscosity of the concrete.

Description

Superplasticizer for ultrahigh-performance concrete and preparation method thereof

Technical Field

The invention relates to the field of concrete superplasticizers, in particular to a superplasticizer for ultra-high performance concrete and a preparation method thereof.

Background

The term "concrete" as used herein generally refers indiscriminately to concrete, such as concrete, mortar or grout, which is also applicable elsewhere herein.

The high-performance water reducing agent (especially polycarboxylic acid water reducing agent or polycarboxylic acid superplasticizer) is widely applied and greatly developed since the invention is invented, and becomes an essential component in concrete. Polycarboxylic acid water reducing agents are generally prepared by radical polymerization of vinyl-containing monomers, the main chain of which is generally-CH₂-CH₂-structure or functional group substituted-CH₁-CH₂Structure) and corresponding side chains are mostly water-soluble polyethylene glycol chains, in the concrete, the charged functional groups are adsorbed on the cement particles through electrostatic interaction between the charged functional groups and the surfaces of the cement particles, and the corresponding long side chains prevent the cement particles from approaching each other and agglomerating through steric hindrance (repulsion), so that the wrapped water is released, the workability of the concrete is improved, and the water-cement ratio is reduced.

The ultra-high performance concrete (with the compressive strength of 100MPa and above) is widely concerned due to the excellent service performance, however, the water-gel ratio of the ultra-high performance concrete is extremely low (generally not higher than 0.2), the content of ultrafine powder in the cementing material component is extremely high, and in addition, the total amount of cement in the cementing material is remarkably reduced compared with that of common commercial concrete, so that the concrete has poor fluidity and high viscosity, and becomes one of the key problems restricting construction. However, the traditional polycarboxylic acid superplasticizer is designed for cement, has poor universality in an ultrahigh-performance concrete complex cementing material system and insufficient performance, and is difficult to meet the basic requirements of fluidity and low viscosity.

Aiming at the problems, people develop a new water reducing agent technology which greatly reduces the water-cement ratio of concrete, reduces the shearing resistance and improves the workability.

The water reducing agent of EP1775271A2 is designed to reduce the viscosity of concrete and have good slump retaining performance, but the water reducing agent is designed aiming at common concrete and is difficult to be applied to high/ultrahigh strength concrete.

CN106467604A reports that a viscosity-reducing polycarboxylate superplasticizer is prepared by copolymerizing bifunctionality unsaturated carboxylic ester monomers and unsaturated phosphate ester monomers with unsaturated anhydride and polyether monomers.

CN103553413A discloses a viscosity-adjusting water reducer with introduced viscosity-adjusting monomers (unsaturated alkyl ester, fluorine-containing ester, alkyl acrylamide or concrete thereof), which can effectively reduce the viscosity of the concrete, but has air-entraining function to different degrees.

CN106431060A reports that a viscosity reduction type polycarboxylate superplasticizer for high-strength concrete adopts a scheme of compounding a water reducer, a viscosity reducer and a slump retaining agent, and can reduce the viscosity of the high-strength concrete to different degrees.

CN10147533 discloses an early strength type polycarboxylate compound water reducing agent, adopts compound viscosity reduction component polyethylene glycol, obviously reduces concrete viscosity, satisfies the mobility requirement of concrete construction process.

CN103865007A discloses a preparation method of a viscosity-reducing polycarboxylic acid water reducer, wherein a certain amount of hydrophobic units and hydrophobic groups are introduced and controlled in a carboxylic acid copolymer molecular structure, so that the viscosity of a cement-based material is reduced under the action of the water reducer, and the water reducer has excellent performance.

CN105367721A discloses a preparation method and application of a viscosity-reducing polycarboxylic acid superplasticizer, wherein a monomer b containing a branched side chain and a monomer c containing a rigid ring group are mainly introduced into the structure for free radical polymerization, so that the water-gel ratio of concrete can be greatly reduced, and the viscosity of the concrete can be effectively reduced.

CN106397683A reports a polycarboxylate superplasticizer for reducing the viscosity of high-grade concrete and a preparation method thereof, the polycarboxylate superplasticizer is prepared by polymerizing terminal alkenyl polyoxyethylene ether, unsaturated acid (benzenesulfonic acid, benzoic acid, acrylic acid and the like) and unsaturated ester (unsaturated hydroxy ester) free radicals and then performing molecular rearrangement through a viscosity reduction regulator, and has the effects of high water reduction rate, good viscosity reduction effect and the like.

CN104262550A discloses a preparation method of a viscosity-reducing polycarboxylic acid water reducer, which comprises the steps of preparing unsaturated quaternary ammonium salt by using unsaturated primary amine small monomers, organic small molecules with epoxy groups and halogen-containing groups, and then reacting the unsaturated quaternary ammonium salt with an unsaturated acid tool to prepare the viscosity-reducing polycarboxylic acid water reducer, wherein the reaction is simple and easy to control, and the viscosity of concrete can be effectively reduced.

CN104371081A discloses a preparation method of a rapid dispersion viscosity-reduction type polycarboxylic acid cement dispersant, which uses unsaturated monomolecular monomer containing tertiary amino as a polymeric reducing agent to obtain a hyperbranched polycarboxylic acid cement dispersant, and greatly improves the viscosity of concrete.

The concrete viscosity reducer reported in CN106008784A is prepared by polymerizing 4-hydroxybutyl vinyl polyether, unsaturated amide and unsaturated phosphate, and can reduce the viscosity of concrete without affecting the fluidity of the concrete and improve the pumping construction performance.

The concrete viscosity regulator reported in CN105837740B is a terpolymer prepared by free radical polymerization of a monomer prepared from glycidyl methacrylate and iminodiacetic acid, acrylic acid/methacrylic acid and a cationic monomer, and effectively reduces the viscosity of C50 concrete.

The viscosity reduction type polycarboxylic acid reported in CN105732911B is prepared by polymerizing unsaturated acid, unsaturated polyether macromonomer and N- (4-vinyl benzyl) -N, N-dialkyl amine, has simple reaction, easy preparation and high water reduction rate, and can be used for reducing the viscosity of high-strength (about 0.3) concrete.

The polycarboxylic acid concrete admixture disclosed in CN100402457C is prepared by radical polymerization of (methyl) acrylic acid alkyl ester monomer, specific polyalkylene glycol unsaturated macromonomer and unsaturated acid monomer, wherein the third monomer acrylic acid alkyl ester monomer with hydrophobic effect introduced can effectively help the water reducing agent to reduce the yield stress and viscosity of concrete.

CN105367721B reports a preparation method and application of a viscosity-reducing polycarboxylic acid superplasticizer, wherein the superplasticizer adopts branched side chain polyether to increase the thickness of a water film layer, and introduces other monomers of rigid rings such as vinyl pyrrolidone and the like to improve the degree of molecular conformation extension, thereby greatly reducing the viscosity of high and ultra-high strength concrete.

The concrete viscosity regulator suitable for being compatible with the water reducing agent and reported by CN104973817B is mainly compounded by a clay stabilizer, an air entraining agent, a foam stabilizer and a thickening agent, can reduce ineffective adsorption of the water reducing agent and stabilize bubbles, is suitable for concrete of C30-C50, and improves the workability.

CN104031217B reports a loose anti-sticking high-performance polycarboxylic acid admixture which is finally prepared by aqueous solution polymerization of ester or ether macromonomers, unsaturated carboxyl monomers, organic phosphate compounds and acrylic acid-lignin polymers, can enhance the adsorption of water molecules and can effectively reduce the viscosity of high-strength concrete.

CN109535341A reports a polycarboxylic acid superplasticizer prepared by polyethylene glycol with hydrophobic modified tail end, and the viscosity reduction performance of the polycarboxylic acid superplasticizer is excellent.

CN108623756A reports that polycarboxylic acid prepared by polymerizing N-ethyl perfluorooctyl sulfonamide acrylate can be used for ultrahigh-performance concrete.

However, according to the studies of the inventors, the terminal hydrophobically modified functional group greatly affects the adsorption conformation of the polymer, thereby affecting the steric hindrance thereof, particularly in a cement-based material with a very low water-to-gel ratio, and thus the dispersing ability thereof is limited.

Generally, the surface properties of different particles in the slurry are greatly different, and the adsorption capacities of different surface water reducing agents for attaching different particles are completely different. The adhesion of the common water reducing agent on the surfaces of silica fume and other particles is weak, and the common water reducing agent cannot effectively cover the surfaces of all powder particles. In general concrete, the volume fraction of particles such as silica fume is not high, and the effect is not obvious; however, in the ultra-high performance concrete, the volume fraction of particles such as silica fume is high, and the adsorption capacity of the common water reducing agent to the particles is limited, so that the slurry viscosity is high, and the construction is difficult. In addition, the mixing amount of the common water reducing agent in the concrete with the extremely low water-cement ratio is higher, the effective adsorption efficiency is lower, according to the research of the inventor, the solution residual amount can reach 70-90% of the mixing amount, the interstitial fluid viscosity is extremely high, and the viscosity of the concrete with the ultra-high performance is very unfavorable.

The water reducing agent products mentioned in the prior art cannot solve the problem of particle adsorption capacity of the ultra-high-performance concrete, and the water reducing agents are not specially designed and cannot effectively cover the surfaces of all particles, so that the concrete is poor in fluidity and high in viscosity, the effect of the water reducing agents is very limited, the reported water-cement ratio of the concrete is mostly 0.2-0.35, the water reducing agents belong to conventional high-strength concrete, and the water reducing agents are fresh to the ultra-high-strength concrete.

Disclosure of Invention

The invention provides a superplasticizer with a novel structure and a preparation method thereof, aiming at solving the problems of poor dispersing ability, low water reducing rate and insufficient viscosity reducing effect of the traditional water reducing agent in ultra-high performance concrete. The superplasticizer comprehensively enhances the adhesion capability, thereby effectively reducing the viscosity of slurry, and in addition, compared with the common commercial superplasticizer, the superplasticizer has lower solution viscosity and weaker bridging effect under the condition of the same solution concentration, and compared with the prior art, the superplasticizer can obviously improve the fluidity of ultrahigh-performance concrete and reduce the viscosity of the concrete.

The superplasticizer for the ultrahigh-performance concrete consists of a branched functional group R₂₁And a polymer chain segment of the water reducing agent; each branched functional group R₂₁3-4 water reducing agent polymer chain segments are linked;

the branched functional group R₂₁The structure of (1) comprises an alkylamino phosphoric acid functional group which is connected with an ethyl group or an isopropyl group through a saturated alkyl group or a phenyl group containing 1-9 carbon atoms, wherein two carbon atoms in the ethyl group and the isopropyl group and P are branched sites and are connected with a polymer chain segment of the water reducing agent through a single bond;

the formula of the alkylamino phosphoric acid functional group is as follows:

X₀represents a saturated alkyl group having 1 to 9 carbon atoms or a phenyl group,

R₁₁represents H or a saturated alkyl group having 1 to 4 carbon atoms,

R₁₂represents a saturated alkyl group of 1 to 6 carbon atoms or a phenyl or carboxyl group,

M₁ ⁺represents H⁺Or Na⁺Or K⁺，

R₁₃Represents a hydrogen atom or a methyl group,

represents a connection site with a polymer chain segment of the water reducing agent;

the polymer chain segment of the water reducing agent refers to residues of existing water reducing agent molecules, and is obtained by copolymerization of unsaturated carboxylic acid, unsaturated polyether, unsaturated aminophosphoric acid or aminophosphite acid and/or unsaturated alkoxy phosphonic acid or alkoxy phosphonous acid.

The branched functional group R₂₁It can also consist of an alkylamino phosphoric acid function and an auxiliary branch function;

the structural formula of the auxiliary branch functional group is shown as the following formula (1-2) or (1-3):

wherein R is₁₄And R₁₆Each independently represents H or a methyl group,

Y₀and Y₀' independently represent a carbonyl group, -CH₂-、-CH₂CH₂-or-C₆H₄-CH₂-, represents-C₆H₄-CH₂-o-phenyl-C₆H₄-is linked to a double bond;

R₁₅and R₁₇Each independently represents-OH or H or

In the above general formula (1-2) or (1-3)

hydroxyethyl phosphoric acid or phosphorous acid (R)₁₅And R₁₇When it is a hydroxyl group) or a phosphate or phosphite (R)₁₅And R₁₇When not a hydroxyl group) functional group, linked to an ethyl or isopropyl group through a carbon atom of a hydroxyethyl group and a saturated alkoxy group, ester group or phenoxy group of 1 to 9 carbon atoms, wherein two carbon atoms of the ethyl and isopropyl groups and P are branching sites, with the water-reducing agent polymer chainThe segments are connected by single bonds.

The auxiliary branching functional group is obtained by the ring opening of glycidol and must generate a hydroxyl group.

The weight average molecular weight of the superplasticizer polymer for the ultrahigh-performance concrete is 2000-100000.

The polymer chain segment of the water reducing agent is any one of structures shown in the following general formula (2):

the chirality of the carbon atom is not limited by the general formula (2), and may be in any configuration;

the general formula (2) does not limit the distribution and connection manner of the respective repeating units (segments) in the polymer segment, and may be head-to-head connected or head-to-tail connected, and may be block or random.

Wherein R is₂₂Is a chain link of a polymer, is any one of the following structural formulas 3-1 to 3-3, and R in a single molecule of a polymer superplasticizer₂₂The link structures may be the same or different:

wherein R is₃₃Represents H or methyl.

M₂ ⁺、M₃ ⁺、M₄ ⁺、M₅ ⁺And M₆ ⁺Each independently represents H⁺Or NH₄ ⁺Or Na⁺Or K⁺；

If any structural unit in the structure is connected in the main chain of the polymer and is marked as a chain link, R in the molecule of the super plasticizer polymer₂₂The average number of links is aa;

in the general formula R₂₃、R₂₄、R₂₅、R₂₆And R₃₂Are respectively provided withIndependently represents H or methyl;

z in the structure shown in the general formula (2)₀Represents a carbonyl group or a phenyl group or-OCH₂CH₂-or-OCH₂CH₂CH₂CH₂-or-CO-NH-CH₂CH₂-or- (CH)₂)_pp-, where pp is an integer between 1 and 6, including 1 and 6;

in the general formula (2), mm and nn respectively represent the average number of the repeat units of isopropoxy and ethoxy, and can be integers or not, (mm + nn) is in the range of 8-114, and mm/(mm + nn) is not more than 1/2, so that the water solubility of the polyether and the extensibility of a molecular chain thereof in an aqueous solution can be ensured; the structure represented by the general formula (2) does not limit the connecting sequence of the ethoxy and isopropoxy repeating units, and may be either block or random;

x in the general formula (2)₁Represents a saturated alkyl group having 1 to 9 carbon atoms or a phenyl group;

y in the general formula (2)₁And Y₂Each independently represents a carbonyl group, -CH₂-、-CH₂CH₂-or-C₆H₄-CH₂-, represents-C₆H₄-CH₂-o-phenyl-C₆H₄-is linked to a double bond;

r in the general formula (2)₂₇Represents H or a saturated alkyl radical having 1 to 4 carbon atoms, R₂₈Represents a saturated alkyl group of 1 to 6 carbon atoms or a phenyl or carboxyl group, R₂₉represents-PO₃H₂or-PO₂H₂or-PO₂HNa or-PO₂HK；

R in the general formula (2)₃₀And R₃₁Each independently represents-PO₃H₂or-PO₂H₂or-POH₂Or the corresponding Na salt and potassium salt functional groups.

Aa, bb, cc, dd and ee in the structure shown in the general formula (2) respectively represent the average number of corresponding chain links of a polymer, and a branch functional group R in the polymer molecular structure of the superplasticizer for ultrahigh-performance concrete₂₁Has an average number of ff, and wherein R corresponds to the formula (1-1)₂₁Average number is recorded asff₁If the values of aa, bb, cc, dd, ee and ff need to satisfy the following conditions at the same time: (1) aa/(aa + bb + cc + dd + ee + ff) is more than or equal to 0 and less than or equal to 0.8; (2) bb/(aa + bb + cc + dd + ee + ff) is more than or equal to 0.1 and less than or equal to 0.9; (3) ff/(aa + bb + cc + dd + ee + ff) is more than or equal to 0.05 and less than or equal to 0.9. (4)0.05 ≤ (ff)₁+cc)/(aa+bb+cc+dd+ee+ff)≤0.9。

The framework structure of the superplasticizer for the ultra-high performance concrete is shown as the following formula (3):

wherein R is₂₁Represents a branched functional group.

The preparation method of the superplasticizer for the ultrahigh-performance concrete comprises the steps of polymerizing a phosphorus-containing composition C, a terminal alkenyl amine B, an aldehyde-containing micromolecule D and an optional polymerizable monomer E to form a prepolymer containing a branch functional group capable of undergoing chain transfer, and then carrying out free radical copolymerization with unsaturated carboxylic acid F and unsaturated polyether G to obtain the superplasticizer for the ultrahigh-performance concrete.

Wherein the amount of the polymerizable monomer E is 0 to 80 percent of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the polyether G in the whole reaction.

The terminal alkenylamine B is a structure shown in the following general formula (4) or any mixture of one or more than one of hydrochloride and sulfate corresponding to the structure:

wherein R is₁represents-H or methyl, X represents a saturated alkyl group having 1 to 9 carbon atoms or a phenyl group, R₂Represents H or a saturated alkyl group having 1 to 4 carbon atoms.

The phosphorus-containing composition C is a mixture of a component I and a component J, the component I is one or more than one of phosphorous acid, hypophosphorous acid, sodium hypophosphite and potassium hypophosphite which are randomly mixed, and the component J is one or more than one of phosphoric acid, polyphosphoric acid, pyrophosphoric acid, phosphorus pentoxide, water, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate and potassium dihydrogen phosphate which are mixed;

the total molar amount of hypophosphorous acid and hypophosphites in the phosphorus-containing composition is 5-90% of the total molar amount of terminal alkenylamine B, polymerizable monomer E, unsaturated carboxylic acid F and polyether G.

The molar amount of the terminal alkenyl amine B is 5-90% of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the polyether G. This ratio is to ensure that sufficient branching functionality and characteristic adsorbing groups are incorporated into the product superplasticizer.

The aldehyde group-containing small molecule D is one or more than one arbitrary mixture in the structure shown in the following general formula (5):

wherein R is₃Representing H or a saturated alkyl group containing 1 to 6 carbon atoms or a phenyl or carboxyl group, an excessively long carbon chain would impair the solubility of the small molecule D in the solvent a.

The polymerizable monomer E is one or any mixture of more than one of the following structures represented by the general formula (6):

wherein R is₄Represents H or CH₃Y represents a carbonyl group, -CH₂-、-CH₂CH₂-or-C₆H₄-CH₂-, represents-C₆H₄-CH₂-o-phenyl-C₆H₄-is linked to a double bond;

the unsaturated carboxylic acid F is one or more than one of acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic anhydride, fumaric anhydride, itaconic acid or corresponding sodium, potassium and ammonium salts thereof in any combination.

The unsaturated polyether G is one or more than one arbitrary mixture in the following general formula (7):

wherein R is₆And R₇Each independently represents-H or methyl,

z represents a carbonyl group or a phenyl group or-OCH₂CH₂-or-OCH₂CH₂CH₂CH₂-or-CO-NH-CH₂CH₂-or- (CH)₂)_p-, where p is an integer in the range of 1 to 6, including 1 and 6;

in the general formula (7), m and n respectively represent the number of the repeat units of the isopropoxy group and the ethoxy group, and can be integers or not, the value range of (m + n) is 8-114, and m/(m + n) is not more than 1/2, so that the water solubility of the polyether and the extensibility of a molecular chain thereof in an aqueous solution can be ensured; the structure represented by the general formula (7) does not limit the order of linkage of the ethoxy and isopropoxy repeating units, and may be either block or random.

The value of (m + n) reflects the length of a side chain, and if the value is too small, the side chain is shorter, which does not mean that the dispersant with the structure cannot be prepared, but the short side chain can cause poor dispersing performance, and if the value is too high, the preparation difficulty of the plasticizer is increased, the reaction efficiency is difficult to improve, the conversion rate is low, and in addition, if the side chain is too long, the adsorption group can be shielded by the side chain, so that the improvement of the adhesion capability on the surface of the solid particle is not facilitated to a certain extent.

The molar amount of the aldehyde group-containing small molecule D is 1-3 times of the total amount of the reactive functional groups of the terminal alkenylamine B, wherein the total amount of the reactive functional groups of the terminal alkenylamine B is calculated by the molar amount of the N atom-linked H atoms (denoted as N (B-H)), the amino group conversion efficiency is ensured, the second-stage reaction is prevented from being influenced, and the excessive proportion is not unreactive but is economically disadvantageous.

The phosphorus-containing composition C is used in an amount which simultaneously satisfies the following conditions: (a) the component I is used in a molar amount of P element (denoted as N (I-P)), and a molar amount of H atoms connected with N atoms of the terminal alkenyl amine B is calculated, wherein the ratio is more than or equal to 1 and less than or equal to N (I-P)/N (B-H) and less than or equal to 3, the ratio is to ensure that sites capable of generating branching are reserved at the end of the reaction in the step (1), but the ratio is too high, so that a large amount of residues influence the polymerization reaction in the step (2), and the polymerization conversion rate is low; (b) the ratio of the hypophosphorous acid to the hypophosphorous acid or the hypophosphite in the component I is arbitrary; (c) the molar amount of phosphorus element in the component J is n (J-P), and the molar amount n (E) of the polymerizable monomer E satisfies the following relationship: 1 ≦ n (J-P) + n (I-P) -n (B-H) ]/n (E), component J may not be used when polymerizable monomer E is not used in the preparation of the superplasticizer, said proportions being such as to ensure the efficiency of the ring opening of the epoxide functional groups of monomer E; (d) the molar weights of hydrogen elements and alkali metal ions in the component J are n (J-H) and n (J-M), and the dosage of the hydrogen elements and the alkali metal ions and the dosage of the terminal alkenyl amine B need to satisfy the following relation:

the proportion is to ensure that the terminal alkenyl amine B is in an ionized state, so that the ring opening of the component J to an epoxy functional group is not influenced, and the proportion is over high, cannot react and is unfavorable for economy.

The total molar amount of hypophosphorous acid and hypophosphite in the component I is 5-90% of the total molar amount of terminal alkenylamine B, polymerizable monomer E, unsaturated carboxylic acid F and polyether G. The proportion is to ensure that enough branching sites in the double bond-containing monomer participating in the free radical copolymerization are subjected to chain transfer reaction to generate a branched structure, and the upper limit of the dosage is to ensure the effective content of long side chains in the product superplasticizer so as to ensure the dispersing performance of the product superplasticizer.

The amount of the unsaturated carboxylic acid F is 0 to 80 percent of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the polyether G. The dosage of the unsaturated carboxylic acid F cannot be too high, otherwise, a characteristic adsorption group in the product superplasticizer is polymerized by terminal alkenyl amine B and a polymerizable monomer E and then is connected to a molecule of the superplasticizer; the amount is too low, the adsorption capacity on the surface is limited, and the dispersing capacity and the economical efficiency cannot be superior to those of the ultrahigh-performance concrete.

The amount of polyether G is 10-90% of the total molar amount of terminal alkenyl amine B, polymerizable monomer E, unsaturated carboxylic acid F and polyether G. If the value is too high, the absorption capacity of the superplasticizer is weaker, if the value is too low, the steric hindrance provided after the absorption is smaller, and in addition, the early fluidity of the concrete can be rapidly lost due to the too strong absorption capacity.

The preparation method of the superplasticizer for the ultrahigh-performance concrete comprises the following steps:

(1) adding a certain amount of solvent A and a certain amount of phosphorus-containing composition C into a reactor, adjusting the reactor to 70-120 ℃, uniformly stirring, continuously and uniformly adding terminal alkenyl amine B and micromolecules D containing aldehyde groups into the reactor, after the reaction time is 6-24 hours, adjusting the temperature of the reactor to 0-120 ℃, continuously and uniformly adding polymerizable monomer E into the reactor, after stirring and reacting for 1-24 hours, stopping the reaction, and removing the solvent and the volatilizable organic micromolecules in vacuum to obtain an intermediate mixture;

(2) and (2) carrying out free radical polymerization on all the intermediate mixture prepared in the step (1), unsaturated carboxylic acid F and unsaturated polyether G in an aqueous solution at 0-90 ℃ to prepare the superplasticizer for the ultra-high performance concrete. The polymerization is initiated by an initiator H, and the chain transfer agent K.

The reaction temperature of the first stage in the step (1) is 70-120 ℃, and the reaction time is 6-24 h. In the step (1), the reaction temperature of the second stage is 0-120 ℃, and the reaction time is 1-24 h. The reaction time required for each step depends on the reaction rate and conversion, and the reaction time is longer when the temperature is low.

In the step (2), the reaction temperature is 0-90 ℃, the time is counted when the initiator is added, and the reaction time is accumulated for 1-12 h. Similarly, the reaction temperature of the step depends on the initiation system, generally, the reaction temperature is relatively low by adopting a redox initiation system, and the reaction speed is high and the reaction time is short due to the high generation speed of free radicals; the temperature used is relatively high and the reaction time is long by adopting thermal initiation. The skilled person can adjust itself empirically.

The intermediate mixture, the unsaturated carboxylic acid and the unsaturated polyether are added to the reaction in a single step, in portions or continuously and uniformly over a period of time before the start of the reaction or during the reaction. The initiator is added to the reaction in a manner of adding the initiator at one time before the reaction starts or during the reaction, adding the initiator in batches or continuously and uniformly adding the initiator in a period of reaction time. And timing from the addition of the initiator, reacting for a period of time, and stopping the reaction to obtain the solution of the needed polymer superplasticizer.

The solvent A in the step (1) is any one of water, dimethyl sulfoxide, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone and acetonitrile or a mixture of water, dimethyl sulfoxide, N-dimethylformamide, N-dimethylacetamide and acetonitrile in any proportion.

The initiator H in the step (2) is a conventional radical polymerization initiation system adopted by a person skilled in the art, the initiator can be a thermal initiation or redox initiator, the initiator can be added at one time or continuously and uniformly added within a certain time, and the initiator must meet the following conditions: the initiator can be dissolved in the solvent at corresponding temperature and successfully initiates polymerization, and the initiator is fully decomposed in the reaction process so as to prevent the stability of the polymer from being influenced by the change after the reaction is finished. Including but not limited to the initiator systems listed below:

the thermal initiator is any one of azodiisobutyronitrile, azodiisoheptonitrile, azodiisobutyl amidine hydrochloride, azodiisobutyl imidazoline hydrochloride, ammonium persulfate, potassium persulfate and sodium persulfate;

the redox initiator is formed by combining an oxidant and a reducing agent, wherein the oxidant is any one of hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate;

when the oxidant is hydrogen peroxide, the reducing agent can be one or more than one of saturated alkyl mercaptan containing 2-6 carbon atoms, thioglycolic acid, ascorbic acid or mercaptopropionic acid in any combination, and in addition, one or more than one of ferrous acetate, ferrous sulfate or ferrous ammonium sulfate in any combination can be contained or not contained as a catalyst, and the catalyst is metered by the molar amount of the Fe element and is not more than 10% of the molar amount of the reducing agent. Too high a catalyst level may result in polymer molecular weight runaway.

When the oxidant is any one of ammonium persulfate, potassium persulfate and sodium persulfate, the reducing agent is any one of the following compositions: (1) one or more than one of thioglycolic acid, ascorbic acid, rongalite or mercaptopropionic acid can be combined at will, and in addition, one or more than one of ferrous acetate, ferrous sulfate or ferrous ammonium sulfate can be contained or not contained as a catalyst, and the catalyst is metered by the molar amount of Fe element and is not more than 10% of the molar amount of the reducing agent. Too high a catalyst dosage may cause a runaway polymer molecular weight; (2) one or more than one of sodium bisulfite, sodium sulfite and sodium pyrosulfite in any combination.

The amount of the initiator is calculated based on the following method, if the initiator is a thermal initiator, the mass of the initiator is 0.2-4% of the total mass of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the unsaturated polyether G; in the case of the redox initiator, the molar amount of the oxidant and the reductant is more than 0.2-4% of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the unsaturated polyether G, and the molar ratio of the oxidant to the reductant is 0.25-4.

The chain transfer agent K in the step (2) is a conventional radical polymerization chain transfer agent adopted by a person skilled in the art, and is only used for adjusting the molecular weight of the product superplasticizer so that the weight average molecular weight of the product superplasticizer is between 2000-100000. Chain transfer agents K used include, but are not limited to: (1) a small organic molecule containing a mercapto group, including but not limited to a saturated alkyl thiol containing 2-6 carbon atoms, mercaptoethanol, mercaptoethylamine, cysteine, thioglycolic acid, or mercaptopropionic acid; (2) sodium bisulfite, sodium sulfite, and sodium metabisulfite. The amount of the compound can be adjusted according to the target molecular weight of the product, and is generally 0-15% of the total molar weight of the polymerizable double bonds in the reaction system. The total molar amount of the polymerizable double bonds is numerically equal to the total molar amount of the terminal alkenyl amine B, the polyether G and the unsaturated carboxylic acid F.

The concentration of the effective reactant in the step (1) needs to be determined according to the reaction conditions, the percentage range of the total mass of the typical effective reactant to the total mass of the system is 10-90%, and the reactant needs to be ensured to be in a dissolved state in the system. The effective reactants are a phosphorus-containing composition C, a terminal alkenyl amine B, an aldehyde group-containing small molecule D and a polymerizable monomer E.

The concentration of the effective reactant in step (2) is the concentration of the conventional radical polymerization system adopted by the person skilled in the art, and can be adjusted according to the economy, the monomer feeding sequence and the like, and the typical concentration of the effective reactant is 30-80 wt%, and the effective reactant is the sum of the intermediate mixture, the polyether G and the unsaturated carboxylic acid F.

The weight average molecular weight of the superplasticizer polymer in the sample finally prepared by the invention is between 2000-100000. Too low a level impairs the adsorption capacity and too high a molecular weight can cause side effects such as increased interaction between solid particles by "bridging" and reduced fluidity of concrete, while too fast an adsorption rate leads to a faster loss of fluidity, and additional plasticizer usage is required to achieve the same fluidity, which is disadvantageous in terms of economy and reduced concrete viscosity.

Compared with the common superplasticizer sold in the market, the superplasticizer disclosed by the invention is applied to the ultra-high performance concrete (the water-gel ratio is not higher than 0.2) by referring to the embodiment, the mixing amount of the superplasticizer is correspondingly reduced by 16-42% compared with the mixing amount of the common polycarboxylic acid superplasticizer sold in the market, the viscosity is effectively reduced, and the shear viscosity can be reduced by 20-49%. In addition, the maximum dispersing capacity of the superplasticizer is obviously superior to that of a commercial superplasticizer, the fluidity of concrete can be effectively improved under the condition of extremely low water-to-gel ratio (often not higher than 0.16), and the effective fluidity of concrete can not be realized by the commercial superplasticizer no matter how much the mixing amount is added. It is to be noted that the amount of superplasticizers according to the invention may be increased compared to commercially available superplasticizers in order to achieve the same fluidity in ordinary commercial concrete.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples. All the following units are parts by mass, and all the compounds used are commercial products or synthetic products according to literature reports.

The sources of solvent A, terminal alkenylamine B, aldehyde-based small molecule D, polymerizable monomer E, polyether G (except G3 and G6), unsaturated carboxylic acid F, initiator H, and chain transfer agent K are all commercially available (carbofuran reagent, TCI reagent, Sigma-Aldrich, Huntsman and Ron reagent, etc.). Part of the polyether is industrial and is prepared by ring-opening polymerization of ethylene oxide anion under the catalysis of terminal alkenyl alcohol base, and is produced by Subot corporation.

Table 1 compound names used in the examples

Some of the compounds listed in Table 1 have the following structures:

polyethers G3 and G6 were prepared by dehydrocondensation of the corresponding polyethylene glycols or substituted polyethylene glycol ethers with unsaturated carboxylic acids:

(1) g3: prepared by reacting acrylic acid with amino poly (ethylene oxide-propylene oxide) monomethyl ether (number average molecular weight 2000, m/(m + n) ═ 0.3, from Huntsman).

Dissolving acrylic acid (7.56G, 0.105mol) and amino poly (ethylene oxide-propylene oxide) monomethyl ether (number average molecular weight 2000, 200G, 0.1mol) with 1000mL of dichloromethane, adding DMAP (0.122G, 1mmol), dropwise adding a solution of DCC (22.67G, 0.11mol) dissolved in dichloromethane (200mL) at room temperature, dropwise adding for 4h, continuing stirring for 6h after dropwise adding, filtering to remove white solid precipitate, distilling under reduced pressure, dissolving the obtained pasty solid with dichloromethane, precipitating with diethyl ether, centrifuging, repeating dichloromethane/diethyl ether precipitation for 2 times on the obtained pasty solid, and vacuum drying the final product to obtain monomer G3 with the yield of 83%.

(2) G6: prepared by reacting methacrylic acid with aminopolyethylene glycol (O- (2-aminoethyl) polyethylene glycol, number average molecular weight 5000, number of ethylene glycol repeat units about 113 from Sigma).

Dissolving methacrylic acid (0.0903G, 0.00105mol) and the aminopolyethylene glycol (5G, 0.01mol) by 50mL of dichloromethane, adding DMAP (0.00122G, 0.01mmol), dropwise adding a solution of DCC (0.2267G, 0.001mol) dissolved in dichloromethane (5mL) at room temperature, dropwise adding for 12h to obtain a white precipitate in the system, continuously stirring for 12h after the dropwise adding is finished, filtering, distilling under reduced pressure, dissolving the obtained solid by dichloromethane, precipitating by diethyl ether, filtering, repeatedly precipitating the obtained solid by dichloromethane/diethyl ether for 2 times, and drying the finally obtained product in vacuum to obtain polyether G6 with the yield of 77%.

The following are the specific procedures of the examples, all the reactions are measured based on terminal alkenylamine B, the amount of the substance converted to terminal alkenylamine B is 0.1 molar part, the following table shows the feeding ratios of the examples, the molecular weight of the product is measured by Shimadzu GPC (LC-20A), the gel column is TSK-GELSW series from TOSOH, a differential refractometer is used, and the mobile phase is 0.1MNaNO₃Aqueous solution, polyethylene glycol as the basis for molecular weight determination.

Example 1

(1) Adding acetonitrile (206.58 parts) into a reactor, adding 14.35 parts of phosphorous acid, 0.99 part of hypophosphorous acid (50% aqueous solution containing 0.99 part of water), 0.88 part of sodium hypophosphite, 4.9 parts of anhydrous phosphoric acid and 6 parts of sodium dihydrogen phosphate, adjusting the temperature of the reactor to 70 ℃, uniformly stirring, continuously and uniformly adding 7.112 parts of B1 and D1 (17.14 parts of aqueous solution and 35 wt%) into the reactor respectively, feeding for 6 hours, continuously reacting for 6 hours after the feeding is finished, adjusting the temperature of the reactor to 0 ℃, continuously and uniformly adding 11.414 parts of E1 into the reactor within 2 hours, stopping the reaction after the adding is finished and continuously stirring for 22 hours, and removing the solvent and the volatilizable small organic molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (22.06 parts), polyether G1(125 parts) and the intermediate mixture prepared in the step (1) into a flask, adjusting the temperature of a reactor to 80 ℃, uniformly stirring and mixing, adding 0.422 part of azobisisobutyronitrile powder into the mixture at one time, then uniformly dropwise adding an aqueous solution (20 parts of water) of sodium methacrylate (2.7 parts) and sodium acrylate (1.8 parts) into the mixture, dropwise adding the aqueous solution for 4 hours, starting from monomer dropwise adding, adding 0.422 part of azobisisobutyronitrile powder into the mixture at one time every half an hour for 6 batches, continuously reacting for 3 hours after the feeding is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample-DP 01 with the weight average molecular weight of 67.2 kDa.

Example 2

(1) Adding 11.08 parts of water into a reactor, then adding 26.4 parts of hypophosphorous acid and 1.96 parts of anhydrous phosphoric acid into the reactor, adjusting the temperature of the reactor to 100 ℃, uniformly stirring, continuously and uniformly adding 16.93 parts of B2 and 28.84 parts of D2 into the reactor respectively, wherein the feeding time is 1h, continuing to react for 5h after the feeding is finished, adjusting the temperature of the reactor to 60 ℃, adding 25.626 parts of E2 into the reactor once, continuing to stir for 8h, stopping the reaction, and removing the solvent and the volatile organic micromolecules in vacuum to obtain an intermediate mixture.

(2) Adding water (105.05 parts), polyether G2(240 parts) and the intermediate mixture prepared in the step (1) into a flask, adjusting the temperature of a reactor to 50 ℃, stirring and mixing uniformly, uniformly dropwise adding a mixed aqueous solution (105.05 parts of water) of acrylic acid (7.2 parts) and initiator azodiisobutyramidine hydrochloride (11.59 parts), feeding for 4 hours, continuously reacting for 8 hours after dropwise adding is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP02 with the weight-average molecular weight of 95.1 kDa.

Example 3

(1) Adding water (2382.684 parts) into a reactor, adding 52.8 parts of sodium hypophosphite, 21.6 parts of phosphorus pentoxide (7.8 parts of water in the reaction composition C is contained in a solvent and is not separately listed) and 14.2 parts of disodium hydrogen phosphate into the reactor, adjusting the temperature of the reactor to 120 ℃, uniformly stirring, continuously and uniformly adding 9.356 parts of B3 and 44.4 parts of D3 into the reactor respectively, feeding for 0.5h, continuously reacting for 5.5h after the feeding is finished, adjusting the temperature of the reactor to 80 ℃, continuously and uniformly adding 113.72 parts of E3 into the reactor within 4h, stopping the reaction after the stirring is finished for 4h, and removing the solvent and the volatilizable organic small molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (207.675 parts), polyether G3(400 parts) and the intermediate mixture prepared in the step (1) into a flask, adjusting the temperature of a reactor to 60 ℃, stirring and mixing uniformly, simultaneously, respectively and uniformly dropwise adding a 1.06 part of mercaptopropionic acid aqueous solution (water 69.225 parts), an aqueous solution of ammonium persulfate (2.28 parts dissolved in 69.225 parts of water), 4.16 parts of sodium bisulfite dissolved in 69.225 parts of water), dropwise adding for 3 hours, continuously reacting for 2 hours after the dropwise adding is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP03 with the weight average molecular weight of 49.8 kDa.

Example 4

(1) Adding N, N-dimethylacetamide (75.85 parts), adding 24.6 parts of phosphorous acid, 13.2 parts (50 wt%) of hypophosphorous acid solution and 3.92 parts of anhydrous phosphoric acid, adjusting the temperature of the reactor to 70 ℃, uniformly stirring, continuously and uniformly adding 11.916 parts of B6 and 21.2 parts of D3 into the reactor respectively, wherein the feeding time is 6 hours, continuously reacting for 6 hours after the feeding is finished, adjusting the temperature of the reactor to 100 ℃, continuously and uniformly adding 7.61 parts of E4 into the reactor within 3 hours, stopping the reaction after the stirring is finished for 1 hour, and removing the solvent and the volatile organic small molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (98.55 parts), polyether G4(123 parts) and the intermediate mixture prepared in the step (1) into a flask, adjusting the temperature of a reactor to 40 ℃, adding an aqueous solution (30 wt% and 0.45 part) of hydrogen peroxide into the reactor, stirring and mixing the mixture uniformly, simultaneously uniformly dropwise adding a mixed aqueous solution (0.352 part is dissolved in 98.55 parts of water) of mercaptoethanol (0.936 part) and ascorbic acid into the reactor, dropwise adding the mixed aqueous solution for 1h, continuing to react for 1h after the dropwise adding is finished, adjusting the temperature to room temperature, and stopping the reaction to obtain a superplasticizer sample PCE-DP04 with the weight-average molecular weight of 6.2 kDa.

Example 5

(1) Adding dimethyl sulfoxide (6.57 parts) into a reactor, adding 4.1 parts of phosphorous acid, 33 parts (50 wt%) of hypophosphorous acid solution and 8.9 parts of pyrophosphoric acid (0.9 part of water in the reaction composition C is contained in the hypophosphorous acid solution and is not separately listed), adjusting the temperature of the reactor to 100 ℃, uniformly stirring, continuously and uniformly adding 9.917 parts of B5 and D1 (17.14 parts of aqueous solution and 35 wt%) into the reactor respectively, wherein the feeding time is 12h, continuously reacting for 4h after feeding, adjusting the temperature of the reactor to 80 ℃, continuously and uniformly adding 12.813 parts of E2 into the reactor within 5h, stopping the reaction after continuously stirring for 1h, and removing the solvent and the volatilizable organic small molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (559.39 parts), polyether G5(600 parts) and the intermediate mixture prepared in the step (1) into a flask, adjusting the temperature of a reactor to 5 ℃, adding an aqueous solution of hydrogen peroxide (30 wt%, 2.27 parts) and ferrous sulfate (0.139 part), uniformly stirring and mixing, simultaneously uniformly dropwise adding a mixture of acrylic acid (7.2 parts) and ethanethiol (0.795 part) and an aqueous solution of ascorbic acid (0.88 part is dissolved in 100 parts of water), dropwise adding for 1.5h, continuously reacting for 0.5h after the dropwise adding is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP05 with the weight average molecular weight of 31.9 kDa.

Example 6

(1) Adding N-methyl pyrrolidone (85.89 parts) into a reactor, adding 4.1 parts of phosphorous acid, 6.6 parts (50 wt%) of hypophosphorous acid solution and 9.8 parts of anhydrous phosphoric acid into the reactor, adjusting the temperature of the reactor to 100 ℃, uniformly stirring, continuously and uniformly adding 11.32 parts of B4 and 21.633 parts of D2 into the reactor respectively, feeding for 4 hours, continuously reacting for 2 hours after feeding, adjusting the temperature of the reactor to 80 ℃, continuously and uniformly adding 7.11 parts of E3 into the reactor within 2 hours, stopping the reaction after continuously stirring for 4 hours, and removing the solvent and the volatile organic small molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (21.53 parts), itaconic acid (26 parts) and the intermediate mixture prepared in the step (1) into a flask, adjusting the temperature of a reactor to 35 ℃, stirring and mixing uniformly, adding 0.611 part of azobisisobutyrimidazoline hydrochloride into the reactor at one time, simultaneously and continuously and uniformly dropwise adding a mixed aqueous solution (150 parts of water) of methacrylic acid (8.6 parts) and polyether G6(252.5 parts) into the reactor within 8h, dropwise adding an aqueous solution (7.8 parts of chain transfer agent sodium bisulfite dissolved in 150 parts of water) into the reactor, continuing the reaction for 4h after the addition is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP06 with the weight average molecular weight of 14.6 kDa.

Example 7

(1) Adding water (8.029 parts) into a reactor, adding 30.75 parts of phosphorous acid, 13.2 parts (50 wt%) of hypophosphorous acid solution and 13 parts of potassium hypophosphite into the reactor, adjusting the temperature of the reactor to 80 ℃, uniformly stirring, continuously and uniformly adding 7.112 parts of B1 and 14.8 parts of D3 into the reactor respectively, feeding for 8 hours, continuing to react for 4 hours after the feeding is finished, stopping the reaction, and removing the solvent and the volatile organic small molecules in vacuum to obtain an intermediate mixture. (amount of the polymerizable monomer E used in this example was 0)

(2) Adding water (202.02 parts), polyether G2(120 parts), itaconic acid 6.5 parts and the intermediate mixture prepared in step (1) into a flask, adjusting the temperature of a reactor to 45 ℃, adding hydrogen peroxide (30% aqueous solution, 0.28 part) into the reactor at one time, stirring and mixing uniformly, continuously and uniformly adding a mixed solution (dissolved in 100 parts of water) of acrylic acid (3.6 parts), mercaptopropionic acid (0.795 part) and ascorbic acid (0.44 part) into the reactor, accumulating the feeding time for 45min, continuing the reaction for 15min after the feeding is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP07 with the weight average molecular weight of 22.6 kDa.

Example 8

(1) Adding water (41.80 parts) into a reactor, adding 13.2 parts of hypophosphorous acid, 14.41 parts (85 wt%) of phosphoric acid, 4.35 parts of dipotassium hydrogen phosphate and 6.8 parts of monopotassium phosphate into the reactor, adjusting the temperature of the reactor to 80 ℃, uniformly stirring, continuously and uniformly adding 7.112 parts of B1 and 42.4 parts of D4 into the reactor respectively, adding for 4 hours, continuously reacting for 8 hours after the feeding is finished, adjusting the temperature of the reactor to 60 ℃, continuously and uniformly adding 11.414 parts of E1 into the reactor within 1 hour, continuously stirring for 1 hour to stop the reaction, and removing the solvent and the volatile organic small molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (344.68 parts) and the intermediate mixture prepared in the step (1) into a flask, adjusting the temperature of a reactor to 60 ℃, adding ammonium persulfate (1.08 parts) into the reactor at one time, stirring and mixing uniformly, continuously and uniformly adding a mixed solution (dissolved in 300 parts of water) of polyether G1(900 parts), mercaptopropionic acid (4.24 parts) and ascorbic acid (0.88 part) into the reactor, accumulating the adding time for 4 hours, continuously reacting for 2 hours, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP08 with the weight-average molecular weight of 25.8 kDa.

Example 9

(1) Adding N, N-dimethylformamide (59.18 parts), adding 22.96 parts of phosphorous acid and 7.92 parts of hypophosphorous acid, adjusting the temperature of the reactor to 100 ℃, uniformly stirring, continuously and uniformly adding 9.356 parts of B3 and D1 (51.42 parts of aqueous solution and 35 wt%) into the reactor, respectively, feeding for 5 hours, continuously reacting for 1 hour after the feeding is finished, adjusting the temperature of the reactor to 90 ℃, continuously and uniformly adding 0.948 part of E3 into the reactor within 1 hour, continuously stirring for 2 hours after the feeding is finished, stopping the reaction, and removing the solvent and the volatile organic small molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (30 parts of water) into a flask, adjusting the temperature of a reactor to 75 ℃, adding ammonium persulfate (0.130 part) into the flask at one time, stirring and uniformly mixing, continuously and uniformly adding the intermediate mixture prepared in the step (1), a mixed solution (dissolved in 121.98 parts of water) of polyether G4(54.67 parts) and thioglycolic acid (0.147 part), feeding for 4 hours, adding the rest of ammonium persulfate into the reaction system in 4 batches within 4 hours, adding 0.13 part into the reaction system every 1 hour, continuously reacting for 4 hours after the addition is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP09 with the weight average molecular weight of 37.6 kDa.

Example 10

(1) Adding N, N-dimethylformamide (89.90 parts) into a reactor, then adding 8.2 parts of phosphorous acid and 26.4 parts of hypophosphorous acid (50% aqueous solution), adjusting the temperature of the reactor to 120 ℃, uniformly stirring, continuously and uniformly adding 9.917 parts of B5 and 7.211 parts of D2 into the reactor respectively, feeding for 9 hours, continuing to react for 3 hours after feeding is finished, stopping the reaction, and removing the solvent and the volatile organic small molecules in vacuum to obtain an intermediate mixture. (amount of the polymerizable monomer E used in this example was 0)

(2) Adding water (101.4 parts) into a flask, adjusting the temperature of a reactor to 30 ℃, adding hydrogen peroxide (30% aqueous solution, 1.13 parts) into the flask at one time, stirring and mixing uniformly, continuously and uniformly adding a mixed solution (dissolved in 101.4 parts of water) of the intermediate mixture prepared in the step (1), methacrylic acid (68.8 parts), polyether G4(205 parts), rongalite (0.385 parts) and mercaptoethanol (3.9 parts) into the mixed solution, feeding for 4 hours, continuously reacting for 1 hour after the addition is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP10 with the weight average molecular weight of 16.9 kDa.

Example 11

(1) Adding dimethyl sulfoxide (115.84 parts) into a reactor, adding 3.28 parts of phosphorous acid, 10.56 parts of hypophosphorous acid and 1.96 parts of anhydrous phosphoric acid into the reactor, adjusting the temperature of the reactor to 80 ℃, uniformly stirring, continuously and uniformly adding 9.917 parts of B5 and 14.8 parts of D3 into the reactor respectively, feeding for 4 hours, continuously reacting for 20 hours after the feeding is finished, adjusting the temperature of the reactor to 90 ℃, continuously and uniformly adding 9.131 parts of E1 into the reactor within 0.5 hour, continuously stirring for 2.5 hours after the feeding is finished, stopping the reaction, and removing the solvent and the volatile organic micromolecules in vacuum to obtain an intermediate mixture.

(2) Adding water (30.118 parts) and the intermediate mixture prepared in the step (1) into a flask, then adding hydrogen peroxide (0.45 part, 30 wt%) and ferrous ammonium sulfate (0.003336 parts), stirring and mixing uniformly, adjusting the temperature of the reactor to 40 ℃, continuously and uniformly adding a mixed solution (dissolved in 240.94 parts of water) of acrylic acid (0.72 part), itaconic acid (6.5 parts), polyether G1(80 parts) and mercaptoethanol (0.25 part) into the flask within 2.5h, simultaneously continuously and uniformly adding an ascorbic acid aqueous solution (0.2112 part of ascorbic acid dissolved in 30.118 parts of water) into the flask within 3h, continuously reacting for 1h, adjusting the temperature to room temperature, stopping the reaction, obtaining a sample PCE-DP11 of the superplasticizer with a weight average molecular weight of 63.6 kDa.

Example 12

(1) Adding N, N-dimethylformamide (107.45 parts), adding 3.28 parts of phosphorous acid, 10.56 parts of hypophosphorous acid and 7.84 parts of anhydrous phosphoric acid into the reactor, adjusting the temperature of the reactor to 80 ℃, uniformly stirring, continuously and uniformly adding 11.916 parts of B6 and 63.6 parts of D4 into the reactor respectively, feeding for 1h, continuously reacting for 9h after the feeding is finished, adjusting the temperature of the reactor to 120 ℃, continuously and uniformly adding 10.25 parts of E2 into the reactor within 2.5h, continuously stirring for 0.355 h after the feeding is finished, stopping the reaction, and removing the solvent and the volatilizable organic small molecules in vacuum to obtain an intermediate mixture.

(2) Adding water (62.788 parts) and polyether G2(240 parts) into a flask, stirring and mixing uniformly, adjusting the temperature of a reactor to 90 ℃, continuously and uniformly adding a mixed solution (dissolved in 251.152 parts of water) of the intermediate mixture prepared in the step (1), maleic anhydride (11.76 parts), ascorbic acid (0.704 part) and mercaptopropionic acid (0.254 part) into the reactor, simultaneously continuously and uniformly adding an aqueous sodium persulfate solution (dissolved in 251.152 parts of water) into the reactor for 1h, continuously reacting for 1h after the addition is finished, adjusting the temperature to room temperature, stopping the reaction, and obtaining a superplasticizer sample PCE-DP12 with the weight average molecular weight of 59.4 kDa.

Application examples

The use effect of the superplasticizer is described below by respectively adopting an extremely low water-to-gel ratio cement paste experiment and an ultra-high performance concrete experiment.

The cement (P.O.42.5) is used as the paste, the cement (P.II.52.5) is used as the concrete, and the temperature of all materials is kept constant to the required temperature before the experiment. The comparative sample was a common commercial polycarboxylic acid superplasticizer (commercial 1 is ester type, commercial 2 is ether type, side chain length 2400). It should be noted that all percentages expressed below are in comparison with the corresponding indices in the commercially available samples.

(1) Cement paste

The fluidity of the cement paste is measured according to GB/T8077-2000 'test method for the homogeneity of concrete admixtures', and all the mixing amounts of the dispersing agents are the percentage (wt%) of pure solid relative to the mass of the cement. In order to characterize the dispersion/dispersion retention properties of the samples at very low water-to-gel ratios, a cement paste was prepared using 270g of cement and 30g of silica fume, with the amount of water used being fixed at 53.1 g. The cement and the silica fume are mixed in advance by a mixer to ensure uniformity.

And testing the net slurry fluidity of different superplasticizers based on a standard net slurry stirring process, and simultaneously testing the fluidity of the cement net slurry after being placed for 30 min. The samples prepared in the examples were compared with a sample of a commercially available polycarboxylic acid superplasticizer, with the following results:

TABLE 2 Cement paste test results (20 ℃ C.)

As can be seen from the results in Table 2, although the dispersion ability of the superplasticizer prepared in the examples of the present invention is related to the structural parameters, and is higher or lower, the dispersion performance is much better than that of the commercial sample under the condition of 0.177 water-to-gel ratio, and the fluidity retention ability of most samples except PCE-DP04 and PCE-DP06 is substantially equivalent to that of commercial sample 2 and is more excellent than that of commercial sample 1.

(2) Ultra High Performance Concrete (UHPC) test (Dispersion Performance comparison, mortar)

In order to examine the maximum dispersing capacity of different samples under different mixing amounts, the fluidity of the cement mortar under the condition of extremely low water-cement ratio is examined under the condition of a given mixing ratio.

TABLE 3UHPC mortar mix proportion (by weight)

Cement	Silica fume	Superfine mineral powder	Sand	Water (W)
					0.68	0.12	0.2	0.7	0.15

First studyShear viscosity of the mortar at (240. + -.5) mm initial fluidity, initial slurry rheology curve (reference Conster. build. Mater.2017,149,359-366, maximum shear rate 25S) was measured using Rheometer (Brookfield R/S300 Rheometer)^-1) Selecting for 15s^-1Is compared (the shear rate is at the same level as the rate of slurry handling such as agitation). The V funnel time of the fluidity mortar was also measured, and the results are shown in table 4:

TABLE 4UHPC mortar test results (20 ℃, blank untested)

As can be seen from the results in Table 4, under the conditions of the tested mix ratios, all samples showed a tendency that the fluidity of the mortar increased first and then did not increase any more with the increase of the mix amount, and the fluidity of some samples increased slightly and decreased due to the increase of the viscosity, the slowing of the flow rate and the slight decrease of the fluidity during the measurement time. The maximum fluidity shown in the table is taken as the ultimate water reduction of the sample, i.e. the maximum dispersion that can be achieved, regardless of the amount of sample incorporated.

The maximum dispersancy capacity of all samples in the table is much greater than that of the commercially available samples, which illustrates the superior dispersancy capacity of the samples prepared according to the examples of the present invention. Furthermore, even when the comparative mortar was blended to a flow of 240mm, the samples of the examples of the present invention required a blending amount 0.1 to 0.3 wt% lower than that of the commercially available samples (corresponding to a percentage reduction of 16 to 42%).

Shear viscosity (15 s) of comparative mortar at (240. + -.5) mm fluidity^-1) And the V funnel time, the sample PCE-DP01-12 prepared by the embodiment of the invention can reduce the shear viscosity by 20-49% and the V funnel time by 18-50%, thus fully illustrating the viscosity reduction property of the sample.

(3) Ultra High Performance Concrete (UHPC) test (concrete, with fibers)

The mixing proportion is changed, the application performance of the superplasticizer prepared by the invention in UHPC is inspected, and the concrete mixing proportion is as follows:

TABLE 5UHPC blend ratio (weight ratio, fiber as volume fraction)

Cement	Silica fume	Fly ash	Sand	fiber/V%	Water (W)
						0.75	0.13	0.12	0.9	2	0.148

The cement (P II 52.5) for the small wild field is ordinary river sand, the fiber is steel fiber with the length-diameter ratio of 30 mm and the length-diameter ratio of 50mm, the mixing amount of a superplasticizer PCE-DP01-12, a commercial 1 and a commercial 2 is calculated by using the flexural weight of a cementing material as a reference (unit: mass percent and wt%), in a test, the slump ((20 +/-1) cm) of UHPC is controlled to be equivalent to the slump ((45 +/-2) cm) of UHPC by adjusting the using amount of the superplasticizer, the used novel material is a common and conventional PXP-I concrete defoamer sold by Jiangsu Su Bott GmbH, and the gas content of all groups of UHPC is controlled to be basically consistent by the defoamer. If the concrete fluidity is difficult to reach the indexes, the fluidity of the super plasticizer with the mixing amount of 1.0 wt% is uniformly inspected, and the concrete outlet fluidity of the super plasticizer is inspected. At this yield, the sample dispersing ability has reached a limit, and concrete fluidity is difficult to enhance by adding a superplasticizer.

Adding cement, silica fume, fly ash and sand into a stirrer, stirring for 2min, adding fibers, continuously stirring for 3min, taking out, respectively testing slump and extensibility of UHPC, and recording as 'initial/out-of-machine' and the mixing amount of the used superplasticizer. The results are as follows:

TABLE 6UHPC characterization (20 ℃ C.)

"-" indicates only slump and no spread

It can be seen that the fluidity requirements of such low water-to-cement ratio concrete cannot be met by the commercially available superplasticizers, and the superplasticizer samples prepared by the examples can impart good fluidity to the concrete with a water-to-cement ratio of 0.148. In contrast to the 28-day compressive strength of the concrete, the dispersion properties of the commercial superplasticizers were poor, with a strength slightly lower than that of the samples prepared in the examples, probably due to a slightly poor homogeneity of the slurry and aggregate.

Claims

1. A superplasticizer for ultra-high performance concrete is characterized in that the superplasticizer is composed of a branched functional group R₂₁And a polymer chain segment of the water reducing agent; each branched functional group R₂₁3-4 water reducing agent polymer chain segments are linked;

the formula of the alkylamino phosphoric acid functional group is as follows:

R₁₁represents H or a saturated alkyl group having 1 to 4 carbon atoms,

M₁ ⁺represents H⁺Or Na⁺Or K⁺，

R₁₃Represents a hydrogen atom or a methyl group,

2. The superplasticizer for ultra-high performance concrete according to claim 1, wherein said branching functional group R is a functional group₂₁It can also consist of an alkylamino phosphoric acid function and an auxiliary branch function;

wherein R is₁₄And R₁₆Each independently represents H or a methyl group,

R₁₅and R₁₇Each independently represents-OH or H or

In the above general formula (1-2) or (1-3)

Indicates the attachment site to the polymer segment of the water reducing agent.

3. The superplasticizer for ultra-high performance concrete according to claim 2, wherein R is R₁₅And R₁₇In the case of hydroxyl, the hydroxyethyl phosphoric acid or phosphorous acid is connected to the ethyl or isopropyl group through the carbon atom of the hydroxyethyl group and the saturated alkoxy group, ester group or phenoxy group of 1 to 9 carbon atoms, wherein two carbon atoms of the ethyl and isopropyl groups and P are branched sites, and are connected with the polymer chain segment of the water reducing agent through a single bond.

4. The superplasticizer for ultra-high performance concrete according to claim 2, wherein R is R₁₅And R₁₇When not hydroxyl, the phosphate or phosphite functional group is linked to the ethyl or isopropyl group through a carbon atom of the hydroxyethyl group and a saturated alkoxy group of 1 to 9 carbon atoms, an ester group or a phenoxy group, wherein two carbon atoms of the ethyl and isopropyl groups and P are branching sites, and is linked to the water reducing agent polymer segment through a single bond.

5. The superplasticizer for ultra-high performance concrete according to claim 2, wherein said auxiliary branching functional group is obtained by ring-opening of glycidol.

6. The superplasticizer for ultra-high performance concrete according to any one of claims 1 to 5, wherein the weight average molecular weight of the polymer of the superplasticizer for ultra-high performance concrete is in the range of 2000-100000.

7. The superplasticizer for ultra-high performance concrete according to claim 1, wherein said polymer segment of water reducing agent is any one of the structures according to the following general formula (2):

Wherein R is₂₂Is a chain link of a polymer, is any one of chain link structures shown in the following (3-1) to (3-3), and R in a single molecule of a polymer superplasticizer₂₂The link structures may be the same or different:

wherein R is₃₃Represents H or methyl.

in the general formula R₂₃、R₂₄、R₂₅、R₂₆And R₃₂Each independently represents H or methyl;

z in the structure shown in the general formula (2)₀To representCarbonyl or phenyl or-OCH₂CH₂-or-OCH₂CH₂CH₂CH₂-or-CO-NH-CH₂CH₂-or- (CH)₂)_pp-, where pp is an integer between 1 and 6, including 1 and 6;

in the general formula (2), mm and nn respectively represent the average number of the repeat units of isopropoxy and ethoxy, and can be integers or not, (mm + nn) is in the range of 8-114, and mm/(mm + nn) is not more than 1/2; the structure represented by the general formula (2) does not limit the connecting sequence of the ethoxy and isopropoxy repeating units, and may be either block or random;

Aa, bb, cc, dd and ee in the structure shown in the general formula (2) respectively represent the average number of corresponding chain links of a polymer, and a branch functional group R in the polymer molecular structure of the superplasticizer for ultrahigh-performance concrete₂₁Has an average number of ff, and wherein R corresponds to the formula (1-1)₂₁Average is recorded as ff₁If the values of aa, bb, cc, dd, ee and ff need to satisfy the following conditions at the same time: (1) aa/(aa + bb + cc + dd + ee + ff) is more than or equal to 0 and less than or equal to 0.8; (2) bb/(aa + bb + cc + dd + ee + ff) is more than or equal to 0.1 and less than or equal to 0.9; (3) ff/(aa + bb + cc + dd + ee + ff) is more than or equal to 0.05 and less than or equal to 0.9;(4)0.05≤(ff₁+cc)/(aa+bb+cc+dd+ee+ff)≤0.9。

8. the preparation method of the superplasticizer for ultra-high performance concrete of claim 1, wherein the superplasticizer for ultra-high performance concrete is obtained by polymerizing a phosphorus-containing composition C, a terminal alkenyl amine B, an aldehyde-containing small molecule D and an optional polymerizable monomer E to a prepolymer containing a branch functional group capable of chain transfer, and then carrying out free radical copolymerization with unsaturated carboxylic acid F and unsaturated polyether G;

wherein R is₁represents-H or methyl, X represents a saturated alkyl group having 1 to 9 carbon atoms or a phenyl group, R₂Represents H or a saturated alkyl group having 1 to 4 carbon atoms;

the total molar amount of hypophosphorous acid and hypophosphite in the component I is 5-90% of the total molar amount of terminal alkenyl amine B, polymerizable monomer E, unsaturated carboxylic acid F and polyether G;

the molar amount of the terminal alkenyl amine B is 5-90% of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the polyether G;

wherein R is₃Represents H or a saturated alkyl group containing 1 to 6 carbon atoms or a phenyl or carboxyl group, and an excessively long carbon chain impairs the solubility of the small molecule D in the solvent A;

the molar weight of the aldehyde group-containing small molecule D is 1-3 times of the total amount of the terminal alkenyl amine B active functional groups,

wherein the amount of the polymerizable monomer E is 0 to 80 percent of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the polyether G in the whole reaction;

the unsaturated carboxylic acid F is one or more than one of acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic anhydride, fumaric anhydride, itaconic acid or corresponding sodium, potassium and ammonium salts thereof in any combination;

wherein R is₆And R₇Each independently represents-H or methyl,

in the general formula (7), m and n respectively represent the number of the repeat units of the isopropoxy and the ethoxy, and can be integers or not, the value range of (m + n) is 8-114, and m/(m + n) is not more than 1/2; the structure represented by the general formula (7) does not limit the order of linkage of the ethoxy and isopropoxy repeating units, and may be either block or random;

the amount of the unsaturated carboxylic acid F is 0 to 80 percent of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the polyether G;

the amount of polyether G is 10-90% of the total molar amount of terminal alkenyl amine B, polymerizable monomer E, unsaturated carboxylic acid F and polyether G.

9. The process according to claim 8, wherein the phosphorus-containing composition C is used in an amount such as to satisfy the following conditions: (a) the amount of component I is calculated by the molar amount of P element (denoted as N (I-P)), and the total amount of active functional groups of terminal alkenyl amine B is calculated by the molar amount of H atoms connected by N atoms (denoted as N (B-H)); the ratio of the amount of the component I and the molar weight of H atoms connected by N atoms of the terminal alkenyl amine B is more than or equal to 1 and less than or equal to N (I-P)/N (B-H) and less than or equal to 3; (b) the ratio of the hypophosphorous acid to the hypophosphorous acid or the hypophosphite in the component I is arbitrary; (c) the molar amount of phosphorus element in the component J is n (J-P), and the molar amount n (E) of the polymerizable monomer E satisfies the following relationship: 1 ≦ [ n (J-P) + n (I-P) -n (B-H) ]/n (E), when polymerizable monomer E is not used in the preparation of the superplasticizer, component J may not be used; (d) the molar weights of hydrogen elements and alkali metal ions in the component J are n (J-H) and n (J-M), and the dosage of the hydrogen elements and the alkali metal ions and the dosage of the terminal alkenyl amine B need to satisfy the following relation:

10. the method according to claim 8, characterized in that it comprises in particular the steps of:

(2) and (2) carrying out free radical polymerization on all the intermediate mixture prepared in the step (1), unsaturated carboxylic acid F and unsaturated polyether G in an aqueous solution at 0-90 ℃ to prepare the superplasticizer for the ultra-high performance concrete. Initiating polymerization by adopting an initiator H, wherein a chain transfer agent is K;

The initiator H in step (2) includes, but is not limited to, the following enumerated initiator systems:

the thermal initiator is any one of azodiisobutyronitrile, azodiisoheptonitrile, azodiisobutyramidine hydrochloride, azodiisobutylimidine hydrochloride, ammonium persulfate, potassium persulfate and sodium persulfate;

when the oxidant is hydrogen peroxide, the reducing agent can be one or more than one of saturated alkyl mercaptan containing 2-6 carbon atoms, thioglycolic acid, ascorbic acid or mercaptopropionic acid in any combination, and in addition, one or more than one of ferrous acetate, ferrous sulfate or ferrous ammonium sulfate in any combination can be contained or not as a catalyst, and the catalyst is metered by the molar amount of Fe element and is not more than 10% of the molar amount of the reducing agent;

when the oxidant is any one of ammonium persulfate, potassium persulfate and sodium persulfate, the reducing agent is any one of the following compositions: (1) one or more than one of thioglycolic acid, ascorbic acid, rongalite or mercaptopropionic acid can be combined at will, and in addition, one or more than one of ferrous acetate, ferrous sulfate or ferrous ammonium sulfate can be contained or not contained as a catalyst, and the catalyst is measured by the molar weight of Fe element and is not more than 10% of the molar weight of the reducing agent;

the amount of the initiator is calculated based on the following method, if the initiator is a thermal initiator, the mass of the initiator is 0.2-4% of the total mass of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the unsaturated polyether G; if the initiator is a redox initiator, the initiator accounts for 0.2 to 4 percent of the total molar amount of the terminal alkenyl amine B, the polymerizable monomer E, the unsaturated carboxylic acid F and the unsaturated polyether G calculated by the more molar amount of the oxidant and the reducer, and the molar ratio of the oxidant to the reducer is 0.25 to 4;

the chain transfer agent K in the step (2) comprises (1) saturated alkyl mercaptan containing 2-6 carbon atoms, mercaptoethanol, mercaptoethylamine, cysteine, thioglycolic acid or mercaptopropionic acid; (2) sodium bisulfite, sodium sulfite, and sodium metabisulfite; the dosage of the compound is 0 to 15 percent of the total molar weight of polymerizable double bonds in a reaction system; the total molar amount of the polymerizable double bonds is numerically equal to the total molar amount of the terminal alkenyl amine B, the polyether G and the unsaturated carboxylic acid F.