CN110885389A

CN110885389A - Concrete viscosity reducer synthesized by simple method and preparation method thereof

Info

Publication number: CN110885389A
Application number: CN201911291045.8A
Authority: CN
Inventors: 阿光强; 王磊; 徐顺涛
Original assignee: Yunnan Senbo Concrete Additive Co Ltd
Current assignee: Yunnan Senbo Concrete Additive Co Ltd
Priority date: 2019-12-16
Filing date: 2019-12-16
Publication date: 2020-03-17
Anticipated expiration: 2039-12-16
Also published as: CN110885389B

Abstract

The invention discloses a concrete viscosity reducer synthesized by a simple method and a preparation method thereof. The concrete viscosity reducer disclosed by the invention adopts the most conventional polycarboxylic acid synthetic raw materials, and is simple and safe in synthetic process, easy for industrial production, low in price, green and environment-friendly. The molecular chains are distributed widely by using the standing reaction, so that the molecular chains move more freely, the polymer side chains have compact hydroxyl groups, the interaction force of cement particles is reduced, the viscosity of concrete is obviously reduced, and meanwhile, the strength of the concrete is not influenced and the working performance of the concrete is improved.

Description

Concrete viscosity reducer synthesized by simple method and preparation method thereof

Technical Field

The invention relates to a concrete viscosity reducer synthesized by a simple method and a preparation method thereof, belonging to the technical field of concrete admixtures.

Background

Due to the development of the construction industry, the demand for high-strength concrete is increasing, such as concrete pouring of C50 and above is required for the bottom of an extra-high building and the tower seat of a large bridge. In order to achieve the purpose of high strength of concrete, a mixing plant usually has low water consumption and high consumption of cementing materials, so that the viscosity of the concrete is very high, the fluidity is very poor, and a series of problems such as concrete production, transportation, pumping, construction and the like are easily caused, thereby limiting the popularization and application of the high-strength concrete.

In order to solve the viscosity problem of high-strength concrete, many researchers have started with both the adjustment of admixture and concrete admixture. In the aspect of admixture, fly ash and silica fume are mainly introduced, but the adjusting range is limited; on the other hand, the air entraining agent is properly added into the additive to reduce the viscosity of the concrete, but the increase of the air content can cause certain influence on the strength of the concrete. The patent CN201610331188.7 discloses a concrete viscosity reducer and a preparation method thereof, wherein 4-hydroxybutyl vinyl ether, unsaturated amide and phosphate ester are used as raw materials for polymerization to form the concrete viscosity reducer, and phosphate groups are used for reducing the viscosity of concrete; patent CN201410393433.8 discloses a preparation method of a rapidly-dispersed viscosity-reduced polycarboxylic acid cement dispersant, wherein a hyperbranched polycarboxylic acid cement dispersant is obtained by using unsaturated macromolecules containing tertiary amino groups as a reducing agent capable of participating in polymerization; patent CN201710569448.9 discloses a composite viscosity modifier for a polycarboxylate water reducer, which is composed of acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, sodium allylsulfonate and modified sulfonated cellulose. The concrete viscosity reducer needs to be subjected to a complicated synthesis process, the price of the functional small monomer is relatively high, strict requirements are imposed on production equipment, the production period is long, and the large-scale production is not facilitated.

Disclosure of Invention

Aiming at the problems, the invention provides a concrete viscosity reducer synthesized by a simple method and a preparation method thereof, which utilize the characteristics of easy self-polymerization and high reaction activity of unsaturated carboxylic acid ester, control the molecular weight of a polymer by controlling the reaction concentration and the dosage of a chain transfer agent, an initiator and the like so as to adjust the viscosity of high-grade concrete, have certain water reduction, can obviously reduce the viscosity of the high-grade concrete, and simultaneously do not influence the working performance and the strength of the concrete.

The inventor of the invention finds that when the amount of the unsaturated carboxylic acid ester in the slump retaining agent is increased during the research of the polycarboxylic acid slump retaining agent, the wrapping property and the softness of concrete are obviously improved, but the water reducing performance is influenced. On the basis, researchers try to directly mix unsaturated carboxylic ester with an initiator, a molecular regulator and a reducing agent for reaction, and as a result, the fact that the whole reaction system can be continuously carried out and the crosslinking phenomenon does not occur is found, and a sample is added into concrete in a compounding mode, so that the viscosity and the workability of the concrete are improved to a certain extent. So far, no attempt has been made to synthesize and apply the concrete viscosity reducer or other functional concrete admixture products in a mode of directly polymerizing functional small monomers for mass production.

The concrete viscosity reducer synthesized by the simple method is characterized by being prepared by polymerizing unsaturated carboxylic ester, a molecular regulator, an initiator and a reducing agent; the molar ratio of the unsaturated carboxylic ester to the molecular regulator to the initiator to the reducing agent is 1-1.2: 0.01-0.02: 0.01-0.02: 0.005-0.01: 0.001 to 0.01.

Further, the unsaturated carboxylic ester is one of tert-butyl acrylate, hydroxyethyl acrylate, methyl acrylate and hydroxypropyl acrylate;

further, the molecular regulator is one or more of dodecyl mercaptan, mercaptoethanol, thioglycolic acid, isooctyl 3-mercaptopropionate, mercaptopropanol, thioglycolic acid, sodium formate and sodium hypophosphite;

further, the initiator is one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, dibenzoyl peroxide and cumene hydroperoxide.

Further, the reducing agent is one or more of sodium formaldehyde sulfoxylate, L-sodium ascorbate and ferrous sulfate.

The preparation method of the concrete viscosity reducer synthesized by the simple method comprises the following steps: at normal temperature, adding unsaturated carboxylic ester and deionized water into a reaction kettle, uniformly stirring, sequentially adding a molecular regulator, a reducing agent and an initiator during stirring, stirring for 20 minutes, standing for reaction for 1 hour to obtain the concrete viscosity reducer, wherein the mass concentration of the final viscosity reducer is 18%.

The invention has the beneficial effects that:

1. according to the invention, unsaturated carboxylic ester is directly used for standing and self-polymerizing to form the concrete viscosity reducer, standing reaction is carried out after one-time feeding and stirring are carried out uniformly, the molecular weight distribution of the synthesized polymer is wide, the molecular chain structure is diversified, meanwhile, the molecular side chain contains a large amount of hydroxyl, the molecular side chain and the water reducer are adsorbed to generate a superimposed effect, and are adsorbed on the surface of cement particles, so that the interaction force among the cement particles is reduced, the molecular distribution of the molecular weight is wide, the molecular motion of the polymer is more free, the polymer is more completely contacted with the cement particles, the surface tension of the cement is better improved, and the.

2. The invention utilizes the most conventional synthetic raw materials in the synthesis of the polycarboxylic acid and has low cost. Meanwhile, a one-time feeding mode is adopted, the whole process does not need heating and pressurizing, and compared with a dripping mode, the method has the advantages of low requirement on equipment, short reaction time, simple process and environmental friendliness.

Detailed description of the preferred embodiments

The present invention is further illustrated by the following specific examples.

Example one

A concrete viscosity reducer synthesized by a simple method is prepared by the following steps:

at normal temperature, stirring 170g of tert-butyl acrylate and 821g of deionized water for 5 minutes, uniformly mixing, then sequentially adding 1.6g of mercaptoethanol, 2.4g L-sodium ascorbate, 2.8g of hydrogen peroxide with the concentration of 30% and 3.5g of potassium persulfate in the stirring process, continuously stirring for 20 minutes, fully mixing, standing and reacting for 1 hour to obtain the concrete viscosity reducer.

Example two

stirring 170g of hydroxyethyl acrylate and 796g of deionized water for 5 minutes and uniformly mixing at normal temperature, then sequentially adding 0.8g of mercaptopropanol, 0.8g of sodium hypophosphite, 0.3g of ferrous sulfate and 2.8g of 30% hydrogen peroxide in the stirring process, continuously stirring for 20 minutes and fully mixing, and standing for reacting for 1 hour to obtain the concrete viscosity reducer.

EXAMPLE III

And stirring 170g of methyl acrylate and 804g of deionized water for 5 minutes and uniformly mixing at normal temperature, then sequentially adding 1.4g of isooctyl 3-mercaptopropionate, 1.6g of rongalite and 3.5g of ammonium persulfate in the stirring process, continuously stirring for 20 minutes and fully mixing, and standing for reacting for 1 hour to obtain the concrete viscosity reducer.

Example four

Stirring 170g of hydroxypropyl acrylate and 802g of deionized water for 5 minutes and uniformly mixing at normal temperature, then sequentially adding 0.5g of thioglycolic acid, 1.1g of sodium formate, 1.2g of rongalite, 0.2g of ferrous sulfate and 3.5g of ammonium persulfate in the stirring process, continuously stirring for 20 minutes and fully mixing, and standing for reaction for 1 hour to obtain the concrete viscosity reducer.

The influence of the concrete viscosity reducer synthesized by the simple method, which is prepared in the embodiments 1-4 of the invention, on the performance of high-grade concrete is tested according to national standards GBT50080-2016 standard of methods for testing the performance of common concrete mixtures, JGJ/T283-2012 technical specification of self-compacting concrete application, and GB/T50081-2002 method for testing the mechanical performance of common concrete.

Table 1: concrete mixing proportion

TABLE 1

Table 2: test result of influence of concrete viscosity reducer synthesized by simple method on concrete working performance

TABLE 2

The data in tables 1 and 2 show that the concrete viscosity reducer synthesized by the simple method has good viscosity reducing effect on high-grade concrete, and compared with a standard using pure water-reducing mother liquor, the viscosity reducer with the mixing amount of 0.3 percent can obviously improve the flow rate of the concrete, does not influence the strength of the concrete, and improves the state of the concrete. Examples 1 to 4 illustrate that the synthesis of the invention is not affected by an oxidation-reduction system, and the synthesized concrete viscosity reducer has good viscosity reducing effect as long as the dosage of the molecular regulator, the initiator and the reducing agent is controlled.

FIG. 1: EXAMPLE 2 Effect of the amount of incorporation on the concrete flow Rate

FIG. 1 shows a schematic view of a

Table 3: EXAMPLE 2 Effect of the amount of the admixture on the Strength of the concrete

TABLE 3

To determine the optimum amount of admixture, the effect of the amount of admixture on the concrete flow rate was verified by taking example 2 as an example, and the data in fig. 1 shows that the concrete flow rate is increased with the increase of the amount of admixture, and the flow rate is slowly increased when the amount of admixture is higher than 0.3%; the data of the influence of the mixing amount of the example 2 in the table 2 on the strength of the concrete show that when the mixing amount is less than 0.3%, the strength of the concrete is not influenced, and after the mixing amount is more than 0.3%, the strength of the concrete is reduced along with the increase of the mixing amount, so that the optimal mixing amount of the viscosity reducer is 0.3%.

Claims

1. The concrete viscosity reducer synthesized by a simple method is characterized by being prepared by polymerizing unsaturated carboxylic ester, a molecular regulator, an initiator and a reducing agent; the molar ratio of the unsaturated carboxylic ester to the molecular regulator to the initiator to the reducing agent is 1-1.2: 0.01-0.02: 0.01-0.02: 0.005-0.01: 0.001 to 0.01.

2. The concrete viscosity reducer according to claim 1, wherein the unsaturated carboxylic acid ester is one of tert-butyl acrylate, hydroxyethyl acrylate, methyl acrylate and hydroxypropyl acrylate.

3. The concrete viscosity reducer synthesized by the simple method according to claim 1, wherein the molecular regulator is one or more of dodecyl mercaptan, mercaptoethanol, thioglycolic acid, isooctyl 3-mercaptopropionate, mercaptopropanol, thioglycolic acid, sodium formate and sodium hypophosphite.

4. The concrete viscosity reducer synthesized by the simple method according to claim 1, wherein the initiator is one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, dibenzoyl peroxide and cumene hydroperoxide.

5. The concrete viscosity reducer synthesized by the simple method according to claim 1, wherein the reducing agent is one or more of sodium formaldehyde sulfoxylate, sodium L-ascorbate and ferrous sulfate.

6. The method for preparing the concrete viscosity reducer synthesized by the simple method according to any one of claims 1 to 5 is characterized by comprising the following steps: at normal temperature, adding unsaturated carboxylic ester and deionized water into a reaction kettle, uniformly stirring, sequentially adding a molecular regulator, a reducing agent and an initiator during stirring, stirring for 20 minutes, standing for reaction for 1 hour to obtain the concrete viscosity reducer, wherein the final concentration is 18%.

7. The method for preparing the concrete viscosity reducer synthesized by the simple method according to claim 6, wherein the mass concentration of the concrete viscosity reducer synthesized by the simple method is 18%.