CN102390950A - Slow-release type polycarboxylate slump-retaining agent and preparation method thereof - Google Patents

Abstract

The invention discloses a slow-release polycarboxylic acid-based slump-retaining agent and a preparation method thereof. The slump-retaining agent is composed of unsaturated carboxylic acid (poly)ethylene glycol monoester, unsaturated polyoxyalkylene ether monomer, unsaturated It is formed by mixing and copolymerizing saturated monocarboxylic acid and its derivative monomers, unsaturated ethylenic sulfonic acid and its sodium salt. The slump-retaining agent has a certain number of sulfonic acid groups and structural units such as esters and ether monomers. The synergistic effect of each unit prevents the adsorption of the clay layered porous internal structure, so it has good slump performance. The high-strength retention performance can well solve the compatibility problems of the current green high-performance concrete materials, especially the problem of excessive mud content in sand and gravel materials and the effect of polycarboxylate slump-retaining agents.

Description

Slow-release polycarboxylate slump-retaining agent and preparation method thereof

technical field

The invention relates to the field of preparation of concrete slump-retaining agent, in particular to a slow-release polycarboxylic acid-based slump-retaining agent and a preparation method thereof.

Background technique

Low-carbon green concrete is a development trend that modern high-performance concrete research and application attaches great importance to. A new challenge of concrete admixture technology is to adapt to low-carbon concrete mixed with a large amount of mineral ultra-fine powder, such as fly ash, slag powder, limestone powder, zeolite powder and metakaolin. The composition of fine powder minerals is uncertain, which often leads to problems such as segregation and bleeding of concrete or rapid loss of fluidity. In addition, sand and gravel materials in modern concrete are not all high-quality river sand and crushed pebbles. In practice, machine-made sand and gravel or mixed natural aggregates are often used. Because of the high mud content or clayey stone powder content in them, it often leads to concrete collapse. Fall loss is too fast. For polycarboxylate-based superplasticizers, the compatibility of green high-performance concrete cannot be ignored.

Generally, the molecular structure and performance of polycarboxylate superplasticizers can be adjusted through molecular design. For polycarboxylate-based water reducers, due to the high proportion of carboxylic acid groups and sulfonic acid groups in the molecular structure of the high-efficiency water-reducing components, it is easy to absorb, so when the basic dosage is used, the initial workability requirements of concrete can be met, but its The fluidity retention performance of concrete is far from meeting the requirements of pumping construction. Excessive addition will cause serious segregation and bleeding problems in freshly mixed concrete, which will destroy the constructability and durability of concrete. When the combination method of retarder and high water-reducing polycarboxylate water-reducing agent is used, the problem of excessive concrete slump loss is alleviated to a certain extent, but it is still difficult to adapt to increasingly complex concrete raw materials and high workability. Requirements, there are common problems such as easy segregation and bleeding of concrete, too long setting time and too fast loss of slump.

By adjusting the relative amount of high-efficiency water-reducing components and slow-release components, it can be used as the best way to solve the problems of concrete segregation bleeding, too long retarding time or too fast loss of fluidity. Slow-release polycarboxylate-based slump-retaining agent is used. Because its molecular structure contains less carboxylic acid groups and sulfonic acid groups, most of which are non-polar ester groups, it has high anti-adsorption ability and is suitable for alkaline concrete. In the environment, as time goes on and reacts continuously, more water-reducing components with water-reducing effect can be slowly released to supplement the effective content of water-reducing agent in the freshly mixed cement paste, so it can prevent the problem of rapid loss of concrete fluidity , can continuously repair the construction performance of concrete. At present, domestic and foreign projects have used some polycarboxylate water-reducing and slump-retaining agents, such as a comb-shaped polysulfonic acid structure small slump concrete plastic-retaining agent announced in the patent CN 101774779A, but only suitable for small slump Concrete retaining plastic soft state, can not meet the high fluidity requirement of keeping concrete for a long time; CN 101066851A discloses a kind of polycarboxylate concrete slump retaining agent containing block glue-linked structure; CN1667009A discloses a kind of carboxylic acid grafting Copolymer concrete slump-retaining agent contains dihydroxy polyether and dibasic unsaturated acid anhydride graft unit; CN101708973A is a water-retaining and plastic-retaining polycarboxylate water-reducing agent and its preparation method. It is formed by mixing macromonomers and ether macromonomers. Most of the above-mentioned slump-retaining agents are not ideal for use in concrete with a high content of clay mineral fine powder, and cannot meet the high fluidity requirements of concrete; and CN101798197A discloses A controlled-release polycarboxylate water-reducer and its preparation method for suppressing the influence of aggregate mud content, which is a water-reducer plus a retarder, and then a porous structure physical adsorption method of natural zeolite powder, to the aggregate When the mud content in the material is high, the impact on slump retention is limited. In short, the current slow-release polycarboxylic acid-based slump-retaining agent is often difficult to exert the best effect of slow-release when the clay content of the concrete sand and gravel material is high.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a slow-release polycarboxylate-based slump-retaining agent and its preparation method, which can replace polycarboxylate-based water-reducing agents in equal amounts, and can exhibit high dispersibility after compounding It has excellent performance in the application of ready-mixed commercial concrete and fair-faced concrete in prefabricated components, especially in the field of high-strength and high-performance concrete.

The purpose of the present invention is achieved through the following technical solutions:

The embodiment of the present invention provides a slow-release polycarboxylate-based slump-retaining agent, which is polymerized from the following components by weight percentage, and each component includes:

In the above-mentioned slump-retaining agent, the unsaturated carboxylic acid (poly)ethylene glycol monoester is represented by the following general formula one:

Formula 1 XCOO(R ₁ O)mH

In the above general formula 1, X represents an alkenyl group containing 2 to 4 carbon atoms, R ₁ O represents an oxyethylene group having 2 to 4 carbon atoms, m is the average number of added moles of the oxyethylene group, and m is Any number between 1 and 10.

In the above-mentioned slump-retaining agent, the unsaturated polyoxyalkylene ether monomer is represented by general formula two:

Formula 2 X0(R ₁ O)nH

In the above general formula 2, X represents an alkenyl group containing 2 to 4 carbon atoms, R ₁ O represents an oxyethylene group having 2 to 4 carbon atoms, n is the average number of added moles of the oxyethylene group, and n is Any number between 20 and 100; in the copolymer, one of the unsaturated polyoxyalkylene ether monomers is used alone or two or more are mixed.

In the above-mentioned slump-retaining agent, the unsaturated monocarboxylic acid and its derivative monomers are represented by general formula three:

General formula three

In the above general formula 3, R ₂ represents hydrogen, methyl, R ₃ represents OM ₁ , wherein M ₁ represents hydrogen, methyl, monovalent metal, divalent metal, ammonium or organic amine; in the copolymer, unsaturated monocarboxylic Acid and its derivative monomers are used alone or in combination of two or more.

In the above-mentioned slump-retaining agent, the unsaturated sulfonic acid or its salt includes: allylsulfonic acid or its salt, methallylsulfonic acid or its salt, styrenesulfonic acid or its salt, 2-methylpropene Any one of amido-3-propenesulfonic acid or its salts or a mixture of both.

In the above-mentioned slump-retaining agent, the slump-retaining agent further includes: 0.5-10% of ethylene acetate by mass percentage.

In the above-mentioned slump-retaining agent, the vinyl ester includes: any one or a mixture of vinyl acetate and vinyl propionate.

The embodiment of the present invention also provides a preparation method of a slow-release polycarboxylate slump-retaining agent, the method comprising:

According to the formula described in the above claim 1, each component of the slump-retaining agent is prepared, and the oxidation-reduction initiation system is used to polymerize each component in an aqueous solution at a temperature of 45 to 70 ° C, and the polymer obtained after polymerization is Slump retaining agent.

In the above method, the oxidant in the redox initiation system used is one of hydroperoxide, persulfate or their mixture; the amount of the oxidant is 0.2% of the total weight of monomers in each component ~2.0%;

The reducing agent in the redox initiation system used is one of low-valent compounds of sulfur, L-ascorbic acid or a mixture thereof; the amount of the reducing agent is 0.1 to 1.0% of the total weight of the monomers in each component %.

In the above method, the polymerization reaction speed is controlled in the following manner, the oxidizing agent in the redox initiation system used is formulated into a solution, or the reducing agent is formulated into a solution, or the oxidizing agent and the reducing agent are formulated into a solution respectively, and the The method of adding is to drop the prepared solution into the reaction system to control the polymerization reaction speed, and the dropping time is controlled within 2 to 5 hours.

As can be seen from the technical scheme provided above, in the embodiment of the present invention, by combining unsaturated carboxylic acid (poly)ethylene glycol monoester, unsaturated polyoxyalkylene ether monomer, unsaturated monocarboxylic acid and derivatives thereof Body and unsaturated ethylenic sulfonic acid and its sodium salt are polymerized under the redox initiation system to form a slow-release polycarboxylic acid-based slump-preventing agent. The slump-preventing agent has a certain number of sulfonic acid groups and at the same time There are structural units such as esters and ether monomers, and the synergistic effect of each unit prevents the adsorption of the clay layered porous internal structure. It replaces 10-50% of the high water-reducing polycarboxylic acid-based water-reducing agent in equal amounts, and is compounded into a polymer Carboxylic acid-based high-performance water-reducing agent (concentration 20%, generally 0.5%-1.5% of the total weight of cement), when mixed in a small amount in concrete, it has high water-reducing rate and good slump retention, and can It meets the higher requirements of various constructions under the condition of complex raw materials, and greatly improves the strength and durability of concrete.

Detailed ways

The technical solutions in the present invention will be clearly and completely described below in conjunction with specific embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiments of the present invention are further described in detail below.

The embodiment of the present invention provides a slow-release polycarboxylic acid-based slump-retaining agent, which is polymerized by the following components in weight percentage, and each component includes:

The unsaturated carboxylic acid (poly)ethylene glycol monoester in the above-mentioned slump-retaining agent is represented by the following general formula one:

Formula 1 XCOO(R ₁ O)mH

In the above general formula 1, X represents an alkenyl group containing 2 to 4 carbon atoms, R ₁ O represents an oxyethylene group having 2 to 4 carbon atoms, m is the average number of added moles of the oxyethylene group, and m is Any number between 1 and 10.

The unsaturated polyoxyalkylene ether monomer in the above-mentioned slump-retaining agent is represented by general formula two:

Formula 2 X0(R ₁ O)nH

In the above general formula 2, X represents an alkenyl group containing 2 to 4 carbon atoms, R ₁ O represents an oxyethylene group having 2 to 4 carbon atoms, n is the average number of added moles of the oxyethylene group, and n is Any number between 20 and 100; in the copolymer, one of the unsaturated polyoxyalkylene ether monomers is used alone or two or more are mixed.

The unsaturated monocarboxylic acid and its derivative monomers in the above-mentioned slump-retaining agent are represented by general formula three:

General formula three

In the above general formula 3, R ₂ represents hydrogen, methyl, R ₃ represents OM ₁ , wherein M ₁ represents hydrogen, methyl, monovalent metal, divalent metal, ammonium or organic amine; in the copolymer, unsaturated monocarboxylic Acid and its derivative monomers are used alone or in combination of two or more.

The unsaturated sulfonic acid or its salt in the above-mentioned slump retaining agent includes: allylsulfonic acid or its salt, methallylsulfonic acid or its salt, styrenesulfonic acid or its salt, 2-methacrylamide- 3-propenesulfonic acid or its salts, or a mixture of both.

The above-mentioned slump-retaining agent also includes: 0.5-10% of ethylene acetate in terms of mass percentage; the vinyl ester includes: any one or a mixture of vinyl acetate and vinyl propionate.

The preparation method of the above-mentioned slow-release polycarboxylic acid series slump-retaining agent specifically comprises the following steps:

According to the above formula, the components for the preparation of the slump-preserving agent are taken, and the components are polymerized in an aqueous solution at a temperature of 45-70°C using a redox initiation system, and the polymer obtained after polymerization is the slump-preserving agent.

In the above method, the oxidizing agent in the redox initiation system used is one of hydroperoxide, persulfate or their mixture; the amount of said oxidizing agent is 0.2%～ 2.0%;

The reducing agent in the redox initiation system used is one of the low-valent compounds of sulfur, L-ascorbic acid or their mixture; the amount of the reducing agent is 0.1-1.0% of the total weight of the monomers in each component .

In the above method, the polymerization reaction speed is controlled in the following manner, the oxidizing agent in the redox initiation system used is formulated into a solution, or the reducing agent is formulated into a solution, or the oxidizing agent and the reducing agent are formulated into a solution respectively, and the prepared The solution is added dropwise to the reaction system to control the polymerization reaction speed, and the dropping time is controlled within 2 to 5 hours.

The slow-release polycarboxylate slump-retaining agent (SRPC) prepared in the examples of the present invention is used by arbitrarily adjusting the slow-release polycarboxylate slump-retaining agent (SRPC) and the ester polycarboxylate water reducer (PC ) or ether polycarboxylate water reducer (PE) (such as 3-7:7-3), the problem of concrete slump loss within 1-2 hours can be completely controlled (can be controlled within no more than 10-20%).

In practice, each raw material can be specifically used: unsaturated carboxylic acid (poly)ethylene glycol monoester (a) can be used: (meth) hydroxyethyl acrylate, polyethylene glycol (meth) acrylate with a molecular weight of 250-500 Monoester; unsaturated polyoxyalkylene ether monomer (b) can be used: (meth)allyl polyglycol ether with a molecular weight of 600-5000; unsaturated monocarboxylic acid and its derivative monomer (c) Available: (meth)acrylic acid, (meth)acrylamide, methyl (meth)acrylate, sodium (meth)acrylate, etc.; unsaturated ethylenic sulfonic acid and its sodium salt monomer (d) can be used: (Methyl) allyl sulfonic acid or its salt, styrene sulfonic acid or its salt, 2-methacrylamide-3-propene sulfonic acid or its salt; ethylene acetate monomer (e) is: ethylene ethyl Monomers such as esters, ethylene propionate, etc.; the initiators in the redox initiation system used include: ammonium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, etc., and the reducing agent can be: sodium thiosulfate, Sodium bisulfite, sodium sulfite, stannous sulfate, ferrous sulfate, L-ascorbic acid, etc.; the molecular weight modifier can be mercaptoacetic acid or mercaptopropionic acid, or a mixture of the two; neutralization with sodium hydroxide or sodium carbonate and water mixture.

In the preparation process, the macromonomers (a), (b) are all added before the reaction starts, and the monomers (c), (d), (e) can be added during the reaction, or in batches after the reaction starts Either add continuously, or use these adding methods in combination.

When preparing the slow-release polycarboxylate slump-retaining agent, the conductivity of the deionized water used is 5-30 us/cm, preferably 5-10 us/cm; The amount used is 0.1-1.0% of the total weight of the monomers used, the amount of the molecular weight regulator is 0.1-2.0% of the total weight of the monomers, the mass concentration of the polymerized monomer mixed solution is 50-70%, and the reaction time is controlled within 3-8 hours . The prepared slow-release polycarboxylate slump retaining agent is a light colorless or light yellow transparent liquid with a mass concentration of 30% to 60%.

When the clay content of the concrete sand and gravel material is high, the clay mineral has a huge internal pore structure, which has strong water absorption and adsorption of water reducing agent, so that the current slump retaining agent cannot function. And the sustained-release polycarboxylate slump-retaining agent of the embodiment of the present invention, owing to have certain amount of sulfonic acid group, has structural units such as esters and ether monomers simultaneously, each unit synergistically prevents clay layered The adsorption of the porous internal structure has good slump retention performance, which can well solve the compatibility problem of the current green high-performance concrete materials, especially the sand and gravel materials with excessive mud content and polycarboxylate retention. The effect of the slump agent is brought into play. This more adaptable slow-release polycarboxylate-based slump-retaining agent will be of great significance to the promotion of polycarboxylate-based water reducers in commercial concrete, as well as the development of concrete admixtures and commercial concrete industries. When in use, the slump-retaining agent plays a role by replacing 30-70% of the high-water-reducing polycarboxylate-based water-reducer in an equivalent amount, and compounded into a polycarboxylate-based high-performance water-reducer (concentration: 20%, the general dosage is 0.5-1.5% of the total weight of cement), even if a small amount is added to the concrete, its dispersion performance is reflected in its high water-reducing rate and good slump retention performance, which can meet various conditions of complex raw materials. Higher construction requirements can greatly improve the strength and durability of concrete.

Embodiment two

This embodiment provides a slow-release polycarboxylate-based slump-retaining agent (SRPC). The amounts of the following components used to prepare the slump-retaining agent are all by weight. Add the methacrylic acid polyethylene glycol 400 of 50 weight parts, the methacrylic acid of 10.5 weight parts, the methallyl polyethylene glycol of 360 weight parts in the four-necked glass flask of adding device, reflux condenser, nitrogen protection device. The ethylene acetate of alcohol 2400,17.5 parts by weight, the methyl acrylate of 17.5 parts by weight, the deionized water of 450 parts by weight and the mass concentration of 3.0 parts by weight are the hydrogen peroxide of 27.5%, after being heated up to 65 ℃, at 3 In the reaction vessel, drop simultaneously the monomer aqueous solution and dropwise addition of 10.5 parts by weight of acrylic acid, 10.5 parts by weight of acrylic acid amide, 27.5 parts by weight of sodium methacrylate, and 50 parts by weight of deionized water in the reaction vessel. 2.5 parts by weight of thioglycolic acid and 60 parts by weight of L-ascorbic acid solution with a mass concentration of 2% were mixed, and the reaction temperature was controlled at 65°C. After the addition was completed, the temperature was continued at 65°C for 60 minutes to complete the polymerization reaction. Cool after heat preservation, add 36 parts by weight of NaOH with a mass concentration of 30% for neutralization, and adjust the mass concentration to 45% to obtain the polycarboxylate slump retaining agent of this embodiment. For subsequent comparative experiments, the slump retaining agent was named SRPC-1.

Embodiment Three

This embodiment provides a slow-release polycarboxylate-based slump-retaining agent (SRPC). The amounts of the following components used to prepare the slump-retaining agent are all by weight. Add the allyl polyethylene glycol 2400 of the methacrylic acid polyethylene glycol 200 of 50 weight parts, the methacrylic acid of 10.5 weight parts, 360 weight parts in the four-necked glass flask of adding device, reflux condenser, nitrogen protection device , 12.5 parts by weight of ethylene acetate, 22.5 parts by weight of methyl acrylate, 450 parts by weight of deionized water and 3.0 parts by weight of ammonium persulfate, after heating up to 65 ° C, within 3 hours respectively in the reaction vessel Add dropwise the monomer aqueous solution of the acrylic acid of 10.5 parts by weight, the acrylic acid amide of 10.2 parts by weight, the sodium propylene sulfonate of 22.5 parts, the deionized water of 50 parts by weight and the mercaptoacetic acid of 2.5 parts by weight, 60 parts by weight. The mass concentration of parts by weight is 2% sodium bisulfite solution, the reaction temperature is controlled at 65 ° C, after the dropwise addition is completed, continue to insulate at 65 ° C for 60 minutes to complete the polymerization reaction, cool after the end of the insulation, and add 36 wt. The mass concentration of part is 30% NaOH neutralization, and adjusts mass concentration to 30%, obtains the polycarboxylic acid series slump retaining agent of present embodiment. For subsequent comparative experiments, the slump retaining agent was named SRPC-2.

Embodiment Four

This embodiment provides a slow-release polycarboxylate-based slump-retaining agent (SRPC). The amounts of the following components used to prepare the slump-retaining agent are all by weight. Add 50 parts by weight of hydroxyethyl acrylate, 360 parts by weight of methallyl polyethylene glycol 2400, 35 parts by weight of methyl acrylate, 200 parts by weight in the four-necked glass flask of the nitrogen protection device Parts by weight of deionized water and 1.5 parts by weight of L-ascorbic acid and 2.5 parts by weight of mercaptopropionic acid, after heating up to 65 ° C, were added dropwise to the reaction vessel simultaneously with 27.5 parts by weight of acrylic acid, 12.5 parts by weight of methacrylic acid, 27.5 parts by weight of 2-methacrylamide-3-propenesulfonic acid, 50 parts by weight of deionized water monomer aqueous solution and dropwise mixing 60 parts by weight of 3.5% persulfuric acid Ammonium solution, the reaction temperature is controlled at 65°C. After the dropwise addition, continue to insulate at 65°C for 60 minutes to complete the polymerization reaction, cool after the heat preservation, add 36 parts by weight of NaOH with a mass concentration of 30%, and obtain The polycarboxylate slump-retaining agent of the present embodiment mass concentration 60%. For subsequent comparative experiments, the slump retaining agent was named SRPC-3.

Embodiment five

This embodiment provides a slow-release polycarboxylate-based slump-retaining agent (SRPC). The amounts of the following components used to prepare the slump-retaining agent are all by weight. Add the hydroxyethyl methacrylate of 50 weight parts, the methacrylic acid of 10.5 weight parts, the methallyl polyethylene glycol 2400 of 360 weight parts in the four-necked glass flask of adding device, reflux condenser, nitrogen protection device , 20.5 parts by weight of methyl acrylate, 450 parts by weight of deionized water and 3.0 parts by weight of ammonium persulfate, after heating up to 65 ° C, within 3 hours, dropwise mixed with 28.8 parts by weight of acrylic acid , 7.2 parts by weight of acrylic acid amide, 12.5 parts by weight of sodium propylene sulfonate, 12.5 parts by weight of 2-methacrylamide-3-propylene sulfonic acid, 50 parts by weight of deionized water monomer aqueous solution and dropwise mixed 2.5 parts by weight of mercaptopropionic acid, 60 parts by weight of L-ascorbic acid solution with a mass concentration of 2%, the reaction temperature is controlled at 65°C, after the dropwise addition, continue to be incubated at 65°C for 60 minutes, so that the polymerization reaction is completed, and the insulation After cooling, add 36 parts by weight of NaOH with a mass concentration of 30% for neutralization, and adjust the mass concentration to 40% to obtain the polycarboxylic acid-based slump-retaining agent of this embodiment. For subsequent comparative experiments, the slump retaining agent was named SRPC-4.

Comparative Example 1

This comparative example provides a slow-release polycarboxylate slump-retaining agent (SPC) for comparison. The additions of the following components used to prepare the slump-retaining agent are all by weight. , a thermometer, a dropping device, a reflux condenser, and a four-necked glass flask of a nitrogen protection device add 50 parts by weight of hydroxyethyl acrylate, 360 parts by weight of methallyl polyethylene glycol 2400, 450 parts by weight of The mass concentration of ionized water and 3.0 parts by weight is the hydrogen peroxide of 27.5%. After the temperature is raised to 65° C., in 3 hours, in the reaction vessel, dropwise simultaneously mix 30.5 parts by weight of acrylic acid, 17.5 parts by weight of ethylene acetate, Anhydrous mixed solution of 17.5 parts by weight of methyl acrylate and 5% sodium hydroxymethyl bisulfite solution of 60 parts by weight, the reaction temperature is controlled at 65 ° C, after the dropwise addition, continue to insulate at 65 ° C for 60 minutes, Make the polymerization reaction complete, cool after the heat preservation is over, add 36 parts by weight of NaOH with a mass concentration of 30% for neutralization, and adjust the mass concentration to 45%, to obtain the polycarboxylic acid-based slump-retaining agent of this comparative example. For subsequent comparative experiments, the slump retaining agent was named SPC-1.

Comparative Example Two

This comparative example provides a slow-release polycarboxylate slump-retaining agent (SPC) for comparison. The additions of the following components used to prepare the slump-retaining agent are all by weight. , a thermometer, a dropping device, a reflux condenser, a four-necked glass flask of a nitrogen protection device, add 360 parts by weight of methallyl polyethylene glycol 2400, 12.5 parts by weight of ethylene acetate, 22.5 parts by weight of acrylic acid Methyl ester, 400 parts by weight of deionized water and 3.0 parts by weight of ammonium persulfate, after heating up to 65 ° C, dropwise added 50 parts by weight of methacrylic acid polyethylene glycol 200, 10.5 parts by weight of methacrylic acid, 21.5 parts by weight of acrylic acid, 27.0 parts by weight of hydroxypropyl acrylate, 50 parts by weight of deionized water in aqueous monomer solution and 30 parts by weight of 5% sodium hydroxymethyl bisulfite solution , the reaction temperature is controlled at 65°C. After the dropwise addition, continue to insulate at 65°C for 60 minutes to complete the polymerization reaction. Cool after the heat preservation is completed, add 36 parts by weight of NaOH with a mass concentration of 30% for neutralization, and adjust the mass When the concentration reaches 50%, the polycarboxylate slump retaining agent of this comparative example is obtained, and the slump retaining agent is named SPC-2 for subsequent comparative experiments.

Comparative Example Three

This comparative example provides a slow-release polycarboxylate slump-retaining agent (SPC) for comparison. The additions of the following components used to prepare the slump-retaining agent are all by weight. , a thermometer, a dropping device, a reflux condenser, a four-necked glass flask of a nitrogen protection device, add 5.0 parts by weight of hydroxyethyl acrylate, 1.05 parts by weight of methacrylic acid, 25.0 parts by weight of methacrylic acid polyethylene glycol 400 Monoester, 3.5 parts by weight of methyl acrylate, 160 parts by weight of deionized water, 0.15 parts by weight of L-ascorbic acid and 0.25 parts by weight of mercaptopropionic acid, after heating up to 65 ° C, drop them simultaneously in the reaction vessel within 3 hours Add and mix the hydroxyethyl acrylate of 50 parts by weight, the methacrylic acid of 10.5 parts by weight, the polyethylene glycol 400 monoester of methacrylate of 250 parts by weight, the methyl acrylate of 35 parts by weight, the deionized water of 450 parts by weight monomer aqueous solution and 60 parts by weight of ammonium persulfate solution with a mass concentration of 5%. , adding 36 parts by weight of NaOH with a mass concentration of 30% for neutralization, and adjusting to a concentration of 40%, to obtain the polycarboxylate slump retaining agent of this comparative example, which is used for subsequent comparative experiments, and the slump retainer is named as SPC-3.

Comparative Example Four

This comparative example provides a slow-release polycarboxylate slump-retaining agent (SPC) for comparison. The additions of the following components used to prepare the slump-retaining agent are all by weight. , a thermometer, a dropping device, a reflux condenser, and a four-necked glass flask of a nitrogen protection device were added with 5.0 parts by weight of sodium methacrylate and 250 parts by weight of deionized water. Into the reaction container within 1 hour, drop and mix 260 parts by weight of methoxy polyethylene glycol 1200, 13.5 parts by weight of methacrylic acid, 250 parts by weight of deionized water, and 27.0 parts by weight of acrylic acid hydroxyl A mixed solution of ethyl ester, 2.0 parts by weight of thioglycolic acid and 100 parts by weight of ammonium persulfate solution with a mass concentration of 3.5%, the reaction temperature is controlled at 80-85°C, after the dropwise addition, continue to insulate at 80-85°C In 60 minutes, the polymerization reaction was completed, cooling after the insulation was finished, adding 20 parts by weight of NaOH with a mass concentration of 30% for neutralization, and adjusting the mass concentration to 30%, to obtain the polycarboxylate slump-retaining agent of this comparative example, For subsequent comparative experiments, the slump retaining agent was named SPC-4.

The slump-retaining agent SRPC series that obtains in the embodiment of the present invention contains a certain amount of sulfonic acid groups, and simultaneously contains unsaturated carboxylic acid (poly)ethylene glycol monoester, unsaturated polyoxyethylene ether, unsaturated monocarboxylic acid and Composition of monomers such as its derivatives, the slump-retaining agent SPC series that comparative example obtains basically does not have sulfonic acid group monomer or is less, does not contain unsaturated carboxylic acid polyethylene glycol base ester and unsaturated polyethylene oxide simultaneously in addition Monomers such as base ethers. The slump-retaining agents SRPC-1 to SRPC-4 obtained in the above-mentioned Examples 2-5 and the slump-retaining agents SPC-1-SPC-4 obtained in Comparative Examples 1-4 were respectively tested for cement slurry fluidity and concrete performance. The performance of the water reducing agent prepared in the embodiment of the present invention is further elaborated by application test comparison.

(1) Clean pulp test

According to the GB8077-1997 method of testing the net slurry fluidity of cement, the net slurry fluidity test uses P.O.42.5 Portland cement respectively, and is tested according to different conditions, condition one (100% benchmark cement) and condition two (90% benchmark cement +10 % metakaolin), the results are shown in Table 1.

Table 1 Fluidity Test of Clean Pulp

  Conditions (1) 100% benchmark cement;

Remark

  Condition (2) 10% metakaolin instead of benchmark cement

As can be seen from Table 1, the dispersion of slump-preserving agents SRPC-1 to SRPC-4 in Examples 2 to 5 of the present invention are higher than those of SPC-1 to SPC-4 in Comparative Examples 1 to 4 It can better meet the dispersibility and dispersion retention performance of metakaolin cement paste.

(2) C30 concrete test

Use PO42.5 Portland cement, Class II fly ash, 95 ^# mineral powder, medium fine sand (fineness modulus 2.15, mud content 5.0%), gravel (particle size 5 ~ 25mm, continuous particle size) etc. See Table 2 for the concrete mix ratio. Under the above conditions, the admixture adopts the method of commercially available ester polycarboxylate water reducer (PC) or ether polycarboxylate water reducer (PE) compound slump retaining agent, and the compounding method is as shown in Scheme 1 , shown in two, the effective mass concentration is 10%, scheme (one): ester polycarboxylate water reducer: polycarboxylate slump retaining agent: sodium gluconate=6: 2: 2, compound scheme (two ): ether polycarboxylate water reducer: polycarboxylate slump retaining agent: sodium gluconate = 4:4:2; when mixing concrete, adjust the amount of admixture according to the concrete state, and measure the initial slump of concrete Degree/expansion, 60-minute slump/expansion, the results are shown in Table 3.

Table 2 Concrete test mix ratio (kg/m ³ )

cement sand stone mineral powder fly ash water 230 750 1065 80 70 165

Table 3 Concrete Tests

Remarks Option (1):

Ester polycarboxylate water reducer PC: polycarboxylate slump retaining agent: sodium gluconate = 6:2:2

Option II):

Ether polycarboxylate water reducer PE: polycarboxylate slump retaining agent: sodium gluconate = 4:4:2

Concrete tests show that, compared with the polycarboxylate slump retaining agent SPC series of comparative examples, the polycarboxylate slump retaining agent SRPC series prepared in Examples 2 to 5 can obtain similar slump at the same replacement dosage , but the polycarboxylate slump retaining agent SRPC series can bring greater expansion and slump retention performance of concrete.

In summary, the slump-retaining agent SRPC in the embodiment of the present invention is synthesized using a certain amount of sulfonic acid-based monomers, and contains ester and ether macromonomers at the same time, which improves its ability to maintain the fluidity of concrete over time . When used, it can replace 0-50% of the amount of polycarboxylate water reducer. With the increase of the amount, the slump performance of concrete, the expansion flow performance of concrete and the performance of maintaining the initial flow state will increase.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. a sustained-release polycarboxylic is a slump retaining agent, it is characterized in that, this slump retaining agent is polymerized by following each component by weight percentage, and each component comprises:

2. sustained-release polycarboxylic according to claim 1 is a slump retaining agent, it is characterized in that, said unsaturated carboxylic acid (gathering) ethylene glycol ester is represented by formula one:

General formula one XCOO (R ₁O) mH

X representes to comprise the thiazolinyl of 2～4 carbon atoms, R in the above-mentioned general formula one ₁O representes to have the oxyethylene group of 2～4 carbon atoms, and m is the average addition mole number of the group of oxyethylene group, and m is arbitrary number of 1～10.

3. sustained-release polycarboxylic according to claim 1 is a slump retaining agent, it is characterized in that, said unsaturated polyalkylene oxide base ether monomer is represented by general formula two:

General formula two X0 (R ₁O) nH

X representes to comprise the thiazolinyl of 2～4 carbon atoms, R in the above-mentioned general formula two ₁O representes to have the oxyethylene group of 2～4 carbon atoms, and n is the average addition mole number of the group of oxyethylene group, and n is arbitrary number of 20～100; In multipolymer, unsaturated polyalkylene oxide base ether monomer is for wherein a kind of independent use or two or more mixing are used.

4. sustained-release polycarboxylic according to claim 1 is a slump retaining agent, it is characterized in that, said unsaturated monocarboxylic acid and derivatives monomer thereof are represented by general formula three:

General formula three

R in the above-mentioned general formula three ₂Represent hydrogen, methyl, R ₃Represent OM ₁, M wherein ₁Represent hydrogen, methyl, monovalence metal, divalent metal, ammonium or organic amine; In multipolymer, unsaturated monocarboxylic acid and derivatives monomer thereof are for wherein a kind of independent use or two or more mixing are used.

5. sustained-release polycarboxylic according to claim 1 is a slump retaining agent; It is characterized in that said unsaturated sulfonic acid or its sodium salt comprise: the mixture of any in allyl sulphonic acid or its sodium salt, methallylsulfonic acid or its sodium salt, styrene sulfonic acid or its sodium salt, 2-USAF RH-1-3-propene sulfonic acid or its sodium salt or two kinds.

6. sustained-release polycarboxylic according to claim 1 is a slump retaining agent, it is characterized in that, said slump retaining agent also comprises: vinyl acetate 0.5～10% by mass percentage.

7. sustained-release polycarboxylic according to claim 6 is a slump retaining agent, it is characterized in that, said vinyl ester comprises: the mixture of any in vinyl-acetic ester, the propionate or two kinds.

8. the preparation method that sustained-release polycarboxylic is a slump retaining agent is characterized in that, this method comprises:

By each component that aforesaid right requirement 1～7 each described prescription is got the preparation slump retaining agent, under 45～70 ℃ of temperature, adopt redox initiation system to make each component in the aqueous solution, carry out polymerization, the polymkeric substance that obtains after the polymerization is slump retaining agent.

9. sustained-release polycarboxylic according to claim 8 is the preparation method of slump retaining agent, it is characterized in that, the oxygenant in the redox initiation system of said employing is a kind of in hydroperoxide, the persulphate or their mixture; The consumption of said oxygenant be in each component total monomer weight 0.2%～2.0%;

Reductive agent in the redox initiation system of said employing is a kind of in the sub-compound, L-xitix of sulphur or their mixture; The consumption of said reductive agent be in each component total monomer weight 0.1～1.0%.

10. sustained-release polycarboxylic according to claim 8 is the preparation method of slump retaining agent; It is characterized in that controlled polymerization speed of response in the following manner in the said method is mixed with solution with the oxygenant in the redox initiation system that adopts; Or reductive agent is mixed with solution; Or oxygenant and reductive agent be mixed with solution respectively, through the dropping mode solution of preparation dripped in reaction system and come controlled polymerization speed of response, dropping time to be controlled at 2～5 hours.