CN108083678A - A kind of compound polycarboxylic acids early strength water-reducing agent and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of water-reducing agents for construction, in particular to a composite polycarboxylate early-strength water-reducer and a preparation method thereof. Concentrated aqueous solution, 10-30 parts of high-graft density polycarboxylate early-strength superplasticizer 40% aqueous solution, 1-5 parts of modifier, 50-60 parts of water are fully mixed to prepare a composite polycarboxylic acid Early-strength water reducer, mixed into concrete or concrete products according to 0.80% to 1.20% of the mass of the cementitious material, by promoting the hydration of cement minerals and auxiliary cementitious materials, the water-cement ratio concrete can be reduced for 1 day and 3 days The standard curing strength is increased by 60% to 80%, and the compressive strength of concrete is increased by 40% to 50% after steam curing at 40°C to 50°C for 8 hours. The 28-day compressive strength ratio of concrete mixed with composite polycarboxylate superplasticizer reaches 150 It is suitable for the production of concrete and prefabricated components that have special requirements for early strength, such as prefabricated building parts, concrete pipe piles, and winter concrete.

Description

A kind of composite polycarboxylate early-strength superplasticizer and preparation method thereof

technical field

The invention relates to the technical field of water reducers for construction, and the specific field is a polycarboxylate early-strength water reducer.

Background technique

Water reducer is a concrete admixture that can reduce the amount of mixing water while maintaining the slump of concrete basically unchanged. Most of them are anionic surfactants, such as lignosulfonate, naphthalenesulfonate formaldehyde polymer, etc. After being added to the concrete mixture, it can disperse the cement particles, improve its workability, reduce the unit water consumption, improve the fluidity of the concrete mixture; or reduce the unit cement consumption and save cement.

According to the water reducing and strengthening ability of the water reducing agent, it is divided into ordinary water reducing agent (also known as plasticizer, the water reducing rate is not less than 8%, represented by lignosulfonate), high-efficiency water reducing agent (also known as superplasticizer) Plasticizer, the water reducing rate is not less than 14%, including naphthalene series, melamine series, sulfamate series, aliphatic series, etc.) and high-performance water reducing agent (water reducing rate is not less than 25%, based on polycarboxylic acid It is represented by water reducing agent).

The water-reducing rate of the existing polycarboxylate water-reducing agent is generally less than 30%, which cannot meet the concrete construction requirements of low water-binder ratio, and because of the low water-reducing rate, the amount of cement is large, which not only increases the cost of concrete, but also affects the long-term strength and Durability is adversely affected.

Slow-release effect of grafted copolymerized branched chains: During the preparation of new water-reducers such as polycarboxylate superplasticizers, some branched chains are grafted on the molecules of the water-reduced agent. The branched chains can not only provide space Moreover, in the high alkalinity environment of cement hydration, the branched chain can be cut off slowly, thereby releasing polycarboxylic acid with dispersing effect, which can improve the dispersing effect of cement particles and control the slump. Fall loss.

Contents of the invention

The purpose of the present invention is to provide a composite polycarboxylate early-strength superplasticizer and its preparation method to solve the problem of poor early strength of concrete after the polycarboxylate superplasticizer is added in the prior art, and the long-term strength growth is not fast and the durability performance issues.

To achieve the above object, the present invention provides the following technical solutions:

A composite polycarboxylate early-strength water-reducer, in parts by weight, comprising 10-20 parts of an aqueous solution with a mass fraction of a low-graft density polycarboxylate early-strength water-reducer of 40%, high-graft density polycarboxylate The mass fraction of the early-strength water reducer is 10-30 parts of an aqueous solution of 40%, 1-5 parts of a modifier and 50-60 parts of water.

The composite polycarboxylate early-strength superplasticizer of the present invention, wherein the low-graft density polycarboxylate early-strength superplasticizer is polymerized from small molecule monomers and ether monomers; The body is a mixture of acrylic acid, hydroxyethyl acrylate, and acrylamide. The molar ratio of the three is 0.6~1.0:0~0.3:0~0.1, and the sum of the molar ratios of the three is equal to 1; the molecular weight of the ether monomer is Grade 600-6000 HPEG, TPEG one or a mixture of two, the graft density 20%-30%, the main chain polymerization degree is selected as shown in Figure 1.

The composite polycarboxylate early-strength superplasticizer of the present invention, wherein the high-graft density polycarboxylate early-strength superplasticizer is polymerized from small molecule monomers and ether monomers; The body is acrylic acid; the ether monomer is one or a mixture of HPEG and TPEG with a molecular weight of 3400-6000, and the branching density of side chains is 300%-600%, preferably 400%-500%.

The composite polycarboxylate early-strength superplasticizer of the present invention, wherein the modifier is an acid-decomposed cornstarch-acrylic acid copolymer.

The composite polycarboxylate early-strength water-reducer of the present invention, wherein the synthesis process of the low-graft density and high-graft-density polycarboxylate early-strength water-reducer is as follows:

Step 1, adding a specified amount of water, ether monomers, and small molecule monomers other than acrylic acid to the reactor in parts by weight, and stirring until all the monomer substances are dissolved;

Step 2, in parts by weight, adding a specified amount of aqueous hydrogen peroxide solution with a concentration of 27% into the reaction kettle, and the reaction system spontaneously heats up to a temperature of 30° C. or above;

Step 3, in parts by weight, the specified amount of concentration is 20% to 30% of the acrylic acid aqueous solution, the specified amount of mercaptopropionic acid solution calculated according to the main chain polymerization degree control requirements is 0.8%, and the concentration is 0.8% The L-ascorbic acid aqueous solution is added dropwise to the reaction kettle, wherein: the adding time of the acrylic acid aqueous solution is 1 to 4 hours, and the dropping time of the mercaptopropionic acid aqueous solution and the L-ascorbic acid aqueous solution is 15 to 30 minutes longer than that of the acrylic acid aqueous solution. 1 to 2 hours;

Step 4, in parts by weight, adding a specified amount of aqueous sodium hydroxide solution with a concentration of 30% into the reaction kettle, and adjusting the pH value of the solution to 5-7;

Step 5, adding a specified amount of water into the reactor, and controlling the solid content of the water reducer to 40%±1%.

The preparation method of the composite polycarboxylate early-strength water-reducer described in the present invention is to combine low-graft density polycarboxylate early-strength water-reducer, high-graft-density polycarboxylate early-strength water-reducer, modifier 1. After the water is accurately measured, stir and mix for 20-40 minutes to obtain a composite polycarboxylate superplasticizer.

Compared with the prior art, the beneficial effects of the present invention are:

Add 0.80% to 1.20% of the cementitious material into concrete or concrete products. By promoting the hydration of cement minerals and auxiliary cementitious materials, the 1-day and 3-day standard curing strength of concrete can be increased by 60%. ～80%, 40℃～50℃ steam curing for 8h increases the compressive strength of concrete by 40%～50%, and the 28-day compressive strength ratio of concrete mixed with composite polycarboxylate superplasticizer reaches more than 150%, which is suitable for Production of concrete and prefabricated components that have special requirements for early strength, such as prefabricated building parts, concrete pipe piles, and winter concrete.

Description of drawings

Figure 1 is a graph showing the relationship between the degree of polymerization of the side chains and the grafting density of the side chains of the low graft density polycarboxylate early-strength superplasticizer of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. 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.

Example 1

A composite polycarboxylate early-strength water-reducer, in parts by weight, comprising 10 parts of an aqueous solution with a mass fraction of low-graft density polycarboxylate early-strength water-reducer of 40%, high-graft density polycarboxylate early-strength The mass fraction of water reducing agent is 10 parts of 40% aqueous solution, 1 part of modifier and 50 parts of water.

Among them, the low graft density polycarboxylate early-strength superplasticizer is polymerized from small molecular monomers and ether monomers; the small molecular monomers are mixed with acrylic acid, hydroxyethyl acrylate, and acrylamide. The ratio is 0.6:0.3:0.1; the ether monomer is a mixture of HPEG and TPEG with a molecular weight of 600-6000, the graft density is 20%-30%, and the degree of polymerization of the main chain is selected as shown in Figure 1.

High-graft density polycarboxylate early-strength superplasticizer is polymerized from small molecule monomers and ether monomers; the small molecule monomers are acrylic acid; the ether monomers are mixtures of HPEG and TPEG with a molecular weight of 3400-6000. The branching density of side chains is 400%-500%.

The modifying agent is acid hydrolyzed cornstarch-acrylic acid copolymer.

The synthesis process of low graft density and high graft density polycarboxylate early strength superplasticizer is as follows:

Step 1, adding a specified amount of water, ether monomers, and small molecule monomers other than acrylic acid to the reactor in parts by weight, and stirring until all the monomer substances are dissolved;

Step 2, in parts by weight, adding a specified amount of aqueous hydrogen peroxide solution with a concentration of 27% into the reaction kettle, and the reaction system spontaneously heats up to a temperature of 30° C. or above;

Step 3, in parts by weight, the specified amount of concentration is 20% to 30% of the acrylic acid aqueous solution, the specified amount of mercaptopropionic acid solution calculated according to the main chain polymerization degree control requirements is 0.8%, and the concentration is 0.8% The L-ascorbic acid aqueous solution is added dropwise to the reaction kettle, wherein: the adding time of the acrylic acid aqueous solution is 1 to 4 hours, and the dropping time of the mercaptopropionic acid aqueous solution and the L-ascorbic acid aqueous solution is 15 to 30 minutes longer than that of the acrylic acid aqueous solution. 1 to 2 hours;

Step 4, in parts by weight, adding a specified amount of aqueous sodium hydroxide solution with a concentration of 30% into the reaction kettle, and adjusting the pH value of the solution to 5-7;

Step 5, adding a specified amount of water into the reactor, and controlling the solid content of the water reducer to 40%±1%.

The preparation method of the composite polycarboxylate early-strength water-reducer: accurately measure low-graft density polycarboxylate early-strength water-reducer, high-graft density polycarboxylate early-strength water-reducer, modifier, and water , Stir and mix for 20 to 40 minutes to obtain a composite polycarboxylate early-strength superplasticizer.

Example 2

A composite polycarboxylate early-strength water-reducer, in parts by weight, comprising 20 parts of an aqueous solution with a mass fraction of 40% of the low-graft density polycarboxylate early-strength water-reducer, high-graft density polycarboxylate early-strength The mass fraction of water reducer is 30 parts of 40% aqueous solution, 5 parts of modifier and 60 parts of water.

Among them, the low graft density polycarboxylate early-strength superplasticizer is polymerized from small molecular monomers and ether monomers; the small molecular monomers are mixed with acrylic acid, hydroxyethyl acrylate, and acrylamide. The ratio is 0.7:0.2:0.1; the ether monomer is HPEG with a molecular weight of 600-6000, the graft density is 20%-30%, and the degree of polymerization of the main chain is selected as shown in Figure 1.

High-graft density polycarboxylate early-strength superplasticizer is polymerized from small molecule monomers and ether monomers; the small molecule monomer is acrylic acid; the ether monomer is HPEG with a molecular weight of 3400-6000, and the side chain grafting density 300% to 600%.

The modifying agent is acid hydrolyzed cornstarch-acrylic acid copolymer.

The synthesis process of low graft density and high graft density polycarboxylate early strength superplasticizer is as follows:

Step 1, adding a specified amount of water, ether monomers, and small molecule monomers other than acrylic acid to the reactor in parts by weight, and stirring until all the monomer substances are dissolved;

Step 2, in parts by weight, adding a specified amount of aqueous hydrogen peroxide solution with a concentration of 27% into the reaction kettle, and the reaction system spontaneously heats up to a temperature of 30° C. or above;

Step 3, in parts by weight, the specified amount of concentration is 20% to 30% of the acrylic acid aqueous solution, the specified amount of mercaptopropionic acid solution calculated according to the main chain polymerization degree control requirements is 0.8%, and the concentration is 0.8% The L-ascorbic acid aqueous solution is added dropwise to the reaction kettle, wherein: the adding time of the acrylic acid aqueous solution is 1 to 4 hours, and the dropping time of the mercaptopropionic acid aqueous solution and the L-ascorbic acid aqueous solution is 15 to 30 minutes longer than that of the acrylic acid aqueous solution. 1 to 2 hours;

Step 4, in parts by weight, adding a specified amount of aqueous sodium hydroxide solution with a concentration of 30% into the reaction kettle, and adjusting the pH value of the solution to 5-7;

Step 5, adding a specified amount of water into the reactor, and controlling the solid content of the water reducer to 40%±1%.

The preparation method of the composite polycarboxylate early-strength water-reducer: accurately measure low-graft density polycarboxylate early-strength water-reducer, high-graft density polycarboxylate early-strength water-reducer, modifier, and water , Stir and mix for 20 to 40 minutes to obtain a composite polycarboxylate early-strength superplasticizer.

Example 3

A composite polycarboxylate early-strength water-reducer, in parts by weight, comprising 15 parts of an aqueous solution with a mass fraction of low-graft density polycarboxylate early-strength water-reducer of 40%, high-graft density polycarboxylate early-strength The mass fraction of water reducer is 20 parts of 40% aqueous solution, 3 parts of modifier and 55 parts of water.

Among them, the low graft density polycarboxylate early-strength superplasticizer is polymerized from small molecular monomers and ether monomers; the small molecular monomers are mixed with acrylic acid, hydroxyethyl acrylate, and acrylamide. The ratio is 0.8:0.15:0.05; the ether monomer is TPEG with a molecular weight of 600-6000, the graft density is 20%-30%, and the degree of polymerization of the main chain is selected as shown in Figure 1.

High graft density polycarboxylate early-strength superplasticizer is polymerized from small molecular monomers and ether monomers; small molecular monomers are acrylic acid; ether monomers are TPEG with a molecular weight of 3400-6000, and the side chain grafting density 400% to 500%.

The modifying agent is acid hydrolyzed cornstarch-acrylic acid copolymer.

The synthesis process of low graft density and high graft density polycarboxylate early strength superplasticizer is as follows:

Step 1, adding a specified amount of water, ether monomers, and small molecule monomers other than acrylic acid to the reactor in parts by weight, and stirring until all the monomer substances are dissolved;

Step 2, in parts by weight, adding a specified amount of aqueous hydrogen peroxide solution with a concentration of 27% into the reaction kettle, and the reaction system spontaneously heats up to a temperature of 30° C. or above;

Step 3, in parts by weight, the specified amount of concentration is 20% to 30% of the acrylic acid aqueous solution, the specified amount of mercaptopropionic acid solution calculated according to the main chain polymerization degree control requirements is 0.8%, and the concentration is 0.8% The L-ascorbic acid aqueous solution is added dropwise to the reaction kettle, wherein: the adding time of the acrylic acid aqueous solution is 1 to 4 hours, and the dropping time of the mercaptopropionic acid aqueous solution and the L-ascorbic acid aqueous solution is 15 to 30 minutes longer than that of the acrylic acid aqueous solution. 1 to 2 hours;

Step 4, in parts by weight, adding a specified amount of aqueous sodium hydroxide solution with a concentration of 30% into the reaction kettle, and adjusting the pH value of the solution to 5-7;

Step 5, adding a specified amount of water into the reactor, and controlling the solid content of the water reducer to 40%±1%.

The preparation method of the composite polycarboxylate early-strength water-reducer: accurately measure low-graft density polycarboxylate early-strength water-reducer, high-graft density polycarboxylate early-strength water-reducer, modifier, and water , Stir and mix for 20 to 40 minutes to obtain a composite polycarboxylate early-strength superplasticizer.

The composite polycarboxylate early-strength water reducer of Examples 1-3 is mixed into concrete or concrete products according to 0.80% to 1.20% of the mass of the cementitious material, and by promoting the hydration of cement minerals and auxiliary cementitious materials , to increase the standard curing strength of concrete in 1 day and 3 days compared with water glue by 60% to 80%, and increase the compressive strength of concrete by 40% to 50% in steam curing at 40°C to 50°C for 8 hours. The 28-day compressive strength ratio of the concrete of the superplasticizer reaches more than 150%, which is suitable for the production of concrete and prefabricated components that have special requirements for early strength, such as prefabricated building parts, concrete pipe piles, and winter concrete.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (7)

1. A composite polycarboxylate early-strength water-reducer, characterized in that: in parts by weight, it includes 10 to 20 parts of an aqueous solution with a mass fraction of 40% of a low-graft density polycarboxylate water-reducer, high The graft density polycarboxylate early-strength superplasticizer comprises 10-30 parts of an aqueous solution with a mass fraction of 40%, 1-5 parts of a modifier and 50-60 parts of water. 2. The composite polycarboxylate early-strength water reducer according to claim 1, characterized in that: the low graft density polycarboxylate early-strength water reducer is polymerized by small molecular monomers and ether monomers The small molecular monomer is a mixture of acrylic acid, hydroxyethyl acrylate and acrylamide, the molar ratio of the three is 0.6~1.0:0~0.3:0~0.1, and the sum of the molar ratios of the three is equal to 1; The ether monomer is one or a mixture of HPEG and TPEG with a molecular weight of 600-6000, and the grafting density is 20%-30%. 3. The composite polycarboxylate early-strength water reducer according to claim 1, characterized in that: the high graft density polycarboxylate early-strength water reducer is polymerized by small molecular monomers and ether monomers The small molecule monomer is acrylic acid; the ether monomer is one or a mixture of HPEG and TPEG with a molecular weight of 3400-6000, and the branching density of side chains is 300%-600%. 4. The composite polycarboxylate early-strength superplasticizer according to claim 3, characterized in that: the side chain graft density of the high graft density polycarboxylate early-strength superplasticizer is 400% to 500% . 5. The composite polycarboxylate early-strength water reducer according to claim 1, characterized in that: the modifier is acid-decomposed cornstarch-acrylic acid copolymer. 6. The composite polycarboxylate early-strength water-reducer according to claim 1, characterized in that: the synthesis process of the low-graft density and high-graft-density polycarboxylate early-strength water-reducer is as follows: Step 1, adding a specified amount of water, ether monomers, and small molecule monomers other than acrylic acid to the reactor in parts by weight, and stirring until all the monomer substances are dissolved; Step 2, in parts by weight, adding a specified amount of aqueous hydrogen peroxide solution with a concentration of 27% into the reaction kettle, and the reaction system spontaneously heats up to a temperature of 30° C. or above; Step 3, in parts by weight, the specified amount of concentration is 20% to 30% of the acrylic acid aqueous solution, the specified amount of mercaptopropionic acid solution calculated according to the main chain polymerization degree control requirements is 0.8%, and the concentration is 0.8% The L-ascorbic acid aqueous solution is added dropwise to the reaction kettle, wherein: the adding time of the acrylic acid aqueous solution is 1 to 4 hours, and the dropping time of the mercaptopropionic acid aqueous solution and the L-ascorbic acid aqueous solution is 15 to 30 minutes longer than that of the acrylic acid aqueous solution. 1 to 2 hours; Step 4, in parts by weight, adding a specified amount of aqueous sodium hydroxide solution with a concentration of 30% into the reaction kettle, and adjusting the pH value of the solution to 5-7; Step 5, adding a specified amount of water into the reactor, and controlling the solid content of the water reducer to 40%±1%. 7. The preparation method of the composite polycarboxylate early-strength water reducer according to any one of claims 1-6, characterized in that: low graft density polycarboxylate early strength water reducer, high graft density poly After accurately measuring the carboxylic acid early-strength water reducer, modifier, and water, stir and mix for 20 to 40 minutes to obtain a composite polycarboxylate early-strength water reducer.