CN114213604B - Water reducer for assembled concrete member and preparation method thereof - Google Patents

Abstract

The invention discloses a water reducer for an assembled concrete member and a preparation method thereof, wherein the water reducer is prepared from unsaturated polyoxyethylene ether, crotonic anhydride, ethyl acrylate, 6-acrylamidocaaproic acid and butyl glycolate by carrying out esterification reaction on the 6-acrylamidocaaproic acid and the butyl glycolate, and copolymerizing an esterification product with other unsaturated monomers. The water reducer provided by the invention is a retarding water reducer, and the dispersing agent is introduced to be matched with the water reducer in the use process of the water reducer, so that the fluidity, slump retention and cohesiveness of concrete can be comprehensively improved.

Description

Water reducer for assembled concrete member and preparation method thereof

Technical Field

The invention belongs to the technical field of concrete additives, and particularly relates to a water reducer for an assembled concrete member and a preparation method thereof.

Background

The assembled concrete member is a concrete structure which is formed by assembling and connecting prefabricated members serving as main stress members. Compared with the cast-in-situ construction method, the assembly structure is beneficial to green construction, because the assembly construction can better meet the requirements of land saving, energy saving, material saving, water saving, environmental protection and the like of the green construction, reduces negative effects on the environment, including noise reduction, dust emission prevention, environmental pollution reduction, clean transportation, site interference reduction, water saving, electricity saving, material saving and other resources and energy sources, and follows the principle of sustainable development.

The following problems easily occur in the production process of the existing fabricated concrete member: (1) The phenomenon of unsmooth discharging occurs in the discharging process, and the construction progress is influenced; (2) The slump loss of the freshly mixed concrete is too fast, and particularly, the phenomenon of high temperature in summer is more obvious; (3) After slump is increased by adjusting the mixing amount of the additive, layering segregation phenomenon is easy to occur after vibrating. The above problems have arisen, and certain requirements are imposed on fluidity, slump retention and cohesiveness of concrete of the fabricated member.

The common method is to adjust the type and the mixing amount of the concrete admixture, so that the problems can be solved to a certain extent. The water reducer is more applied, has excellent water reducing effect and good dispersing effect, but is rarely applied to the assembled concrete member on the market, and is difficult to comprehensively meet the performance requirements.

In summary, how to design a water reducer for an assembled concrete member, which can improve the fluidity, slump retention and cohesiveness of concrete in the use process at the same time, is a problem that needs to be solved at present.

Disclosure of Invention

The invention aims to solve the technical problems and provide a water reducer for an assembled concrete member and a preparation method thereof, wherein the fluidity, slump retention and cohesiveness of concrete can be comprehensively improved by preparing a retarding water reducer and introducing a dispersing agent to be matched with the water reducer in the use process.

The invention realizes the aim through the following technical scheme, and the water reducer for the fabricated concrete member is prepared from the following raw materials of unsaturated polyoxyethylene ether, crotonic anhydride, ethyl acrylate, 6-acrylamidocaaproic acid and butyl glycolate in a molar ratio of 1: (0.08-0.16): (0.15-0.35): (0.1-0.3): (0.2-0.4).

Further, the molecular weight of the unsaturated polyoxyethylene ether is 400-2400, specifically allyl polyoxyethylene ether or isopentenyl polyoxyethylene ether.

The invention also provides a preparation method of the water reducer for the fabricated concrete member, which specifically comprises the following steps:

(1) Heating 6-acrylamidocaaproic acid to 100-110 ℃, adding a catalyst, uniformly mixing, then dropwise adding butyl glycolate, and carrying out esterification reaction under the stirring condition of 110-120 ℃ for 5-6h to obtain an esterification product;

(2) Adding unsaturated polyoxyethylene ether, crotonic anhydride and deionized water into a reaction kettle, regulating the temperature of the reaction kettle to 70-80 ℃, respectively dropwise adding the esterified product obtained in the step (1), ethyl acrylate and an initiator aqueous solution, and stirring for reaction for 3-5h after the dropwise adding is finished, thus obtaining a finished product of the slow-release water reducer.

Further, in the step (1), the catalyst is concentrated sulfuric acid, and the addition amount of the concentrated sulfuric acid is 1-2% of the total amount of reactants.

In the step (2), the initiator is one of azodiisobutyronitrile, benzoyl peroxide/N, N-dimethylaniline and tert-butyl hydroperoxide/sodium metabisulfite, and the mass ratio of the initiator to the unsaturated polyoxyethylene ether is (0.8-1.4): 100; the addition amount of deionized water is 50-80% of the total mass of polyoxyethylene ether and crotonic anhydride, and the mass ratio of the initiator to water in the initiator aqueous solution is 1: (2-4).

The invention also provides a use method of the water reducer for the fabricated concrete member, the prepared water reducer and the dispersing agent are uniformly mixed, then the cementing material and the aggregate are added, and then the mixing water is added for full stirring, so that the material can be discharged.

Wherein, the mixing amount of the water reducing agent and the dispersing agent is respectively 0.1 to 0.16 percent and 0.8 to 1.4 percent of the cementing material.

Further, the active ingredients of the dispersing agent are amphoteric polymers, the preparation raw materials of the amphoteric polymers comprise vinyl ether, 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride, N, N, N-trimethyl-9-octadecene-1-ammonium chloride and oleic acid, and the molar ratio of the amphoteric polymers is 1: (0.1-0.3): (0.3-0.5): (0.4-0.7).

Further, the preparation method of the amphoteric polymer comprises the following steps:

s1, mixing 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride with deionized water to prepare a solution I, and mixing N, N, N-trimethyl-9-octadecene-1-ammonium chloride with deionized water to prepare a solution II;

s2, placing vinyl ether and oleic acid into a reaction kettle, adjusting the temperature of the reaction kettle to 80-90 ℃, respectively dropwise adding the solution I, the solution II and the aqueous solution of the initiator, and stirring for reaction for 4-6 hours after the dropwise adding is finished, thus obtaining the amphoteric polymer finished product.

Further, in step S1, the mass concentration of the first solution is 30-40%, and the mass concentration of the second solution is 50-60%.

The initiator in the step S2 is ammonium persulfate or benzoyl peroxide, and the mass ratio of the initiator to vinyl ether is (1-2): 100, the mass ratio of the initiator to water in the initiator aqueous solution is 1: (1-2).

The invention also provides a preparation method of the dispersing agent in the use method of the water reducing agent, which comprises the following specific steps: concentrating the prepared amphoteric polymer solution under reduced pressure, and vacuum drying at 40-50deg.C until the water content is less than or equal to 2% to obtain solid powder; mixing the obtained solid powder with starch and porous ceramic powder, dispersing in a dispersing machine of 1000-2000r/min, spraying sodium alginate material liquid, and drying to obtain the final product.

Further, the sodium alginate material liquid comprises 10-20 parts of sodium alginate, 2-4 parts of talcum powder, 3-6 parts of phospholipid and 120-240 parts of deionized water;

the mass ratio of the solid powder to the starch to the porous ceramic powder is 1: (0.4-0.6): (10-18), and the spraying amount of the sodium alginate material liquid is 3-5%.

The invention has the beneficial effects that:

(1) The water reducer prepared by the invention is a slow-release water reducer, and is introduced into the fabricated concrete for use, so that the dispersion effect of the water reducer on cement particles can be continuously and slowly carried out, and the slump retaining performance of the concrete can be remarkably improved;

(2) When the water reducer is prepared, the side chain containing ester groups and amido groups is introduced into the molecules of the water reducer, so that the water reducer can be slowly hydrolyzed under alkaline conditions, carboxyl groups are continuously released, and a slow release effect is achieved;

(3) The side chain synthesized by 6-acrylamidocaaproic acid and butyl glycolate is introduced into the water reducer, the side chain contains an amido and two ester groups, the three groups can be gradually and slowly hydrolyzed, the slow release effect is further improved, and along with the gradual hydrolysis of the three groups, the length of the side chain is gradually reduced, so that the aim of slowly improving the coagulation effect of cement is also achieved;

(4) Because the water reducer for the assembled concrete member needs certain fluidity requirement, the water reducer is a slow-release water reducer, and when the water reducer is applied to concrete, the water reducer is accompanied by hydrolytic fracture of chain segments, so that the length of branched chains can be reduced, the dispersing effect of the water reducer is affected, and the later fluidity is reduced;

(5) The active ingredient of the dispersing agent prepared by the invention is an amphoteric polymer which contains an anionic branched chain and a cationic branched chain with long chain segments and short chain segments alternately, and has better dispersing effect;

(6) Because the amphoteric polymer in the dispersing agent has long chain branched chains and good dispersibility, but the coagulation effect of the water reducing agent on cement can be influenced after the amphoteric polymer is added, when the dispersing agent is prepared, the amphoteric polymer is subjected to slow release treatment, so that the release of the amphoteric polymer can be slowed down, the dispersion effect can be slowly exerted, and the influence on the coagulation effect of the water reducing agent can be avoided;

(7) When the dispersing agent is prepared, firstly, the amphoteric polymer is loaded in the porous ceramic powder, then the sodium alginate material liquid is used for coating treatment, and the sodium alginate is slightly soluble in water but soluble in alkaline solution, so that the coating formed by the sodium alginate material liquid can be slowly dissolved in alkaline cement mortar, the amphoteric polymer is released, and the dispersing effect of the amphoteric polymer is slowly exerted;

(8) In the preparation of the dispersing agent, the phospholipid which is a natural amphoteric molecule is also added into the sodium alginate material liquid, so that the release of the amphoteric polymer of the coating can be promoted.

Detailed Description

The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

The embodiment provides a water reducer for an assembled concrete member, wherein the preparation raw materials of the water reducer comprise allyl polyoxyethylene ether (with the molecular weight of 400-2400), crotonic anhydride, ethyl acrylate, 6-acrylamidocaaproic acid and butyl glycolate, and the molar ratio is 1:0.08:0.15:0.1:0.2.

the preparation method of the water reducer comprises the following steps:

(1) Heating 6-acrylamidocaaproic acid to 100 ℃, adding concentrated sulfuric acid, uniformly mixing, adding butyl glycolate dropwise, and carrying out esterification reaction under the stirring condition at 110 ℃ for 5 hours to obtain an esterification product, wherein the addition amount of the concentrated sulfuric acid is 1% of the total amount of reactants;

(2) Adding allyl polyoxyethylene ether, crotonic anhydride and deionized water (the addition amount is 50% of the total mass of the polyoxyethylene ether and the crotonic anhydride) into a reaction kettle, then adjusting the temperature of the reaction kettle to 70 ℃, respectively dropwise adding the esterified product obtained in the step (1), ethyl acrylate and an initiator aqueous solution, stirring and reacting for 3 hours after the dropwise adding, and finally adjusting the solid content of the reaction solution to 40%, thus obtaining the finished product of the slow-release water reducer.

In the step (2), the initiator is azodiisobutyronitrile, and the mass ratio of the initiator to the unsaturated polyoxyethylene ether is 0.8:100; the mass ratio of the initiator to the water in the initiator aqueous solution is 1:2.

example 2

On the basis of the embodiment 1, the embodiment also provides a use method of the water reducer for the fabricated concrete member, the prepared water reducer and the dispersing agent are uniformly mixed, the mixing amount of the water reducer and the dispersing agent is respectively 0.1% and 0.8% of that of the cementing material, the cementing material and the aggregate are added, and then the mixing water is added for full stirring, so that the material can be discharged.

The active ingredients of the dispersing agent are amphoteric polymers, the preparation raw materials of the amphoteric polymers comprise vinyl ether, 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride, N, N, N-trimethyl-9-octadecene-1-ammonium chloride and oleic acid, and the molar ratio is 1:0.1:0.3:0.4.

the preparation method of the amphoteric polymer comprises the following steps:

s1, mixing 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride with deionized water to prepare a solution I with the mass concentration of 30%, and mixing N, N, N-trimethyl-9-octadecene-1-ammonium chloride with deionized water to prepare a solution II with the mass concentration of 50%;

s2, placing vinyl ether and oleic acid into a reaction kettle, adjusting the temperature of the reaction kettle to 80 ℃, respectively dropwise adding the solution I, the solution II and the aqueous solution of the initiator, and stirring for reaction for 4 hours after the dropwise adding is finished, thus obtaining the amphoteric polymer finished product.

The initiator in the step S2 is ammonium persulfate, and the mass ratio of the initiator to vinyl ether is 1:100, the mass ratio of the initiator to water in the initiator aqueous solution is 1:1.

the remainder was the same as in example 1.

Example 3

On the basis of the embodiment 2, the embodiment also provides a preparation method of the dispersing agent in the using method of the water reducing agent, which comprises the following specific steps: taking the prepared amphoteric polymer solution, concentrating under reduced pressure, and vacuum drying at 40 ℃ until the water content is less than or equal to 2%, thus obtaining solid powder; mixing the obtained solid powder with starch and porous ceramic powder according to the mass ratio of 1:0.4:10, dispersing in a dispersing machine of 1000r/min, spraying sodium alginate material liquid (the spraying amount is 3%), and drying to obtain the finished product of the dispersing agent.

The sodium alginate material liquid comprises 10 parts of sodium alginate, 2 parts of talcum powder, 3 parts of phospholipid and 120 parts of deionized water.

The remainder was the same as in example 2.

Example 4

The embodiment provides a water reducer for an assembled concrete member, wherein the water reducer comprises the following raw materials in terms of preparation, namely allyl polyoxyethylene ether, crotonic anhydride, ethyl acrylate, 6-acrylamidocaaproic acid and butyl glycolate, and the molar ratio is 1:0.12:0.25:0.2:0.3.

the preparation method of the water reducer comprises the following steps:

(1) Heating 6-acrylamidocaaproic acid to 105 ℃, adding concentrated sulfuric acid, uniformly mixing, wherein the addition amount of the concentrated sulfuric acid is 1.5% of the total amount of reactants, then dropwise adding butyl glycolate, and carrying out esterification reaction under the stirring condition of 115 ℃ for 5.5 hours to obtain an esterification product;

(2) Adding allyl polyoxyethylene ether, crotonic anhydride and deionized water (the addition amount is 65% of the total mass of the polyoxyethylene ether and the crotonic anhydride) into a reaction kettle, then adjusting the temperature of the reaction kettle to 75 ℃, respectively dropwise adding the esterified product obtained in the step (1), ethyl acrylate and an initiator aqueous solution, stirring and reacting for 4 hours after the dropwise adding, and finally adjusting the solid content of the reaction solution to 40%, thus obtaining the finished product of the slow-release water reducer.

In the step (2), the initiator is benzoyl peroxide/N, N-dimethylaniline, and the mass ratio of the initiator to the unsaturated polyoxyethylene ether is 1.1:100; the mass ratio of the initiator to the water in the initiator aqueous solution is 1:3.

the embodiment also provides a use method of the water reducer for the fabricated concrete member, the prepared water reducer and the dispersing agent are uniformly mixed, the mixing amount of the water reducer and the dispersing agent is respectively 0.13% and 1.1% of that of the cementing material, the cementing material and the aggregate are added, and then the mixing water is added for full stirring, so that the material can be discharged.

The active ingredients of the dispersing agent are amphoteric polymers, the preparation raw materials of the amphoteric polymers comprise vinyl ether, 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride, N, N, N-trimethyl-9-octadecene-1-ammonium chloride and oleic acid, and the molar ratio is 1:0.2:0.4:0.55.

the preparation method of the amphoteric polymer comprises the following steps:

s1, mixing 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride with deionized water to prepare a solution I with the mass concentration of 35%, and mixing N, N, N-trimethyl-9-octadecene-1-ammonium chloride with deionized water to prepare a solution II with the mass concentration of 55%;

s2, placing vinyl ether and oleic acid into a reaction kettle, adjusting the temperature of the reaction kettle to 85 ℃, respectively dropwise adding the solution I, the solution II and the aqueous solution of the initiator, and stirring for reaction for 5 hours after the dropwise adding is finished, thus obtaining the amphoteric polymer finished product.

The initiator in the step S2 is ammonium persulfate or benzoyl peroxide, and the mass ratio of the initiator to vinyl ether is 1.5:100, the mass ratio of the initiator to water in the initiator aqueous solution is 1:1.5.

the embodiment also provides a preparation method of the dispersing agent in the use method of the water reducing agent, which comprises the following specific steps: taking the prepared amphoteric polymer solution, concentrating under reduced pressure, and vacuum drying at 45 ℃ until the water content is less than or equal to 2%, thus obtaining solid powder; mixing the obtained solid powder with starch and porous ceramic powder according to the mass ratio of 1:0.5:14, dispersing in a 1500r/min dispersing machine, spraying sodium alginate material liquid (the spraying amount is 4%), and drying to obtain the finished product of the dispersing agent.

The sodium alginate material liquid comprises 15 parts of sodium alginate, 3 parts of talcum powder, 4.5 parts of phospholipid and 180 parts of deionized water.

Example 5

The embodiment also provides a water reducer for an assembled concrete member, wherein the preparation raw materials of the water reducer comprise isopentenyl polyoxyethylene ether, crotonic anhydride, ethyl acrylate, 6-acrylamidocaaproic acid and butyl glycolate, and the molar ratio is 1:0.16:0.35:0.3:0.4.

the preparation method of the water reducer comprises the following steps:

(1) Heating 6-acrylamidocaaproic acid to 110 ℃, adding concentrated sulfuric acid, uniformly mixing, adding butyl glycolate dropwise, and carrying out esterification reaction under the stirring condition of 120 ℃ for 6 hours to obtain an esterification product, wherein the addition amount of the concentrated sulfuric acid is 2% of the total amount of reactants;

(2) Adding isopentenyl polyoxyethylene ether, crotonic anhydride and deionized water (the addition amount is 80% of the total mass of the polyoxyethylene ether and the crotonic anhydride) into a reaction kettle, then adjusting the temperature of the reaction kettle to 80 ℃, respectively dropwise adding the esterified product obtained in the step (1), ethyl acrylate and an initiator aqueous solution, stirring and reacting for 5 hours after the dropwise adding, and finally adjusting the solid content of the reaction solution to 40%, thus obtaining the finished product of the slow-release water reducer.

In the step (2), the initiator is tert-butyl hydroperoxide/sodium metabisulfite, and the mass ratio of the initiator to the unsaturated polyoxyethylene ether is 1.4:100; the mass ratio of the initiator to the water in the initiator aqueous solution is 1:4.

the embodiment also provides a use method of the water reducer for the fabricated concrete member, the prepared water reducer and the dispersing agent are uniformly mixed, the mixing amount of the water reducer and the dispersing agent is respectively 0.16% and 1.4% of that of the cementing material, the cementing material and the aggregate are added, and then the mixing water is added for full stirring, so that the material can be discharged.

The active ingredients of the dispersing agent are amphoteric polymers, the preparation raw materials of the amphoteric polymers comprise vinyl ether, 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride, N, N, N-trimethyl-9-octadecene-1-ammonium chloride and oleic acid, and the molar ratio is 1:0.3: 0.5:0.7.

the preparation method of the amphoteric polymer comprises the following steps:

s1, mixing 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride with deionized water to prepare a solution I with the mass concentration of 40%, and mixing N, N, N-trimethyl-9-octadecene-1-ammonium chloride with deionized water to prepare a solution II with the mass concentration of 60%;

s2, placing vinyl ether and oleic acid into a reaction kettle, then adjusting the temperature of the reaction kettle to 90 ℃, respectively dropwise adding the solution I, the solution II and the aqueous solution of the initiator, and stirring for reaction for 6 hours after the dropwise adding is finished, thus obtaining the amphoteric polymer finished product.

The initiator in the step S2 is ammonium persulfate or benzoyl peroxide, and the mass ratio of the initiator to vinyl ether is 2:100, the mass ratio of the initiator to water in the initiator aqueous solution is 1:2.

the embodiment also provides a preparation method of the dispersing agent in the use method of the water reducing agent, which comprises the following specific steps: taking the prepared amphoteric polymer solution, concentrating under reduced pressure, and vacuum drying at 50 ℃ until the water content is less than or equal to 2%, thus obtaining solid powder; mixing the obtained solid powder with starch and porous ceramic powder according to the mass ratio of 1:0.6:18, dispersing in a dispersing machine at 2000r/min, spraying sodium alginate material liquid (the spraying amount is 5%), and drying to obtain the finished product of the dispersing agent.

The sodium alginate material liquid comprises 20 parts of sodium alginate, 4 parts of talcum powder, 6 parts of phospholipid and 240 parts of deionized water.

Comparative example 1

The difference between this comparative example and example 3 is that the water reducer is a polycarboxylic acid type water reducer which is commercially available.

Comparative example 2

This comparative example differs from example 4 in that the dispersant is a conventional anionic dispersant, specifically sodium oleate.

Comparative example 3

This comparative example differs from example 4 in that the amphoteric polymer is an amphoteric surfactant, in particular a phospholipid.

Comparative example 4

This comparative example differs from example 4 in that the amphoteric polymer is an amphoteric surfactant, specifically alkyl dimethyl betaines.

Comparative example 5

The comparative example differs from example 4 in that the water reducing agent is incorporated in an amount of 0.08% of the cement.

Comparative example 6

The comparative example differs from example 4 in that the water reducing agent is incorporated in an amount of 0.18% of the cement.

Comparative example 7

This comparative example differs from example 4 in that the dispersant is incorporated at 0.6% of the cement.

Comparative example 8

This comparative example differs from example 4 in that the dispersant is incorporated at 1.6% of the cement.

Comparative example 9

This comparative example differs from example 5 in that the dispersant was prepared by the following method: taking the prepared amphoteric polymer solution, concentrating under reduced pressure, and vacuum drying at 50 ℃ until the water content is less than or equal to 2%, thus obtaining solid powder; the mass ratio of the obtained solid powder to the porous ceramic powder is 1:18, dispersing in a dispersing machine at 2000r/min, spraying sodium alginate material liquid (the spraying amount is 5%), and drying to obtain the finished product of the dispersing agent.

Comparative example 10

This comparative example differs from example 5 in that the dispersant was prepared by the following method: taking the prepared amphoteric polymer solution, concentrating under reduced pressure, adding starch, granulating by a granulator, dispersing in a 2000r/min dispersing machine, spraying sodium alginate material liquid (the spraying amount is 5%), and drying to obtain a finished product of the dispersing agent.

Comparative example 11

The difference between this comparative example and example 5 is that the sodium alginate material liquid does not include phospholipids.

Comparative example 12

The difference between this comparative example and example 5 is that the sodium alginate material liquid does not include talc.

1. Performance detection of the water reducer prepared by the invention

The water reducers prepared in examples 3 to 5 of the present invention and the water reducer of comparative example 1 were added to reference concrete according to GB 8076-2008 "concrete admixture", and performance tests were performed, respectively, and the results are shown in Table 1.

TABLE 1

As is clear from the results in Table 1, the water reducers prepared according to the methods of examples 3 to 5 of the present invention have better properties and a slump change of less than 10mm with time, and are free from segregation phenomenon, and can meet the performance requirements of the fabricated concrete member, compared with comparative example 1 (commercially available polycarboxylic acid type water reducer).

2. The application method of the water reducer prepared by the invention in concrete is tested

The water reducers prepared in examples 1 to 5 and comparative examples 1 to 12 according to the present invention were applied to concrete formulation according to the use method of the present invention, slump change of concrete slurry was measured and segregation phenomenon was observed, wherein slump measurement was referred to GB/T50080-2016 Standard for test method for Performance of ordinary concrete mixtures, and the results are shown in Table 2.

TABLE 2

As can be seen from the results in Table 2, the water reducer and the use method thereof according to examples 3 to 5 of the present invention can significantly improve the fluidity and slump retention of concrete without segregation.

Compared with example 1, the water reducer of example 2 added with the dispersant during use, the fluidity of the concrete was significantly improved, but the slump loss thereof was gradually increased, and a slight segregation phenomenon occurred; in order to solve the problems caused by the addition of the dispersing agent, examples 3 to 5 carried out a slow release treatment of the effective components (amphoteric polymer) in the dispersing agent, and as a result, the slump retaining property was remarkably improved and segregation phenomenon did not occur.

Comparative examples 2 to 8 changed the type of dispersant and the effective ingredient in the dispersant as compared with example 4; comparative examples 9 to 12 each changed the preparation method of the dispersant as compared with example 5; as a result, the fluidity and slump retention of the concrete of comparative examples 2 to 12 were affected to different degrees, and segregation phenomenon occurred in comparative examples 2, 9 to 12. It is described that the performance of concrete can be effectively improved only by preparing the amphoteric polymer according to the method of the present invention and preparing the amphoteric polymer as an effective ingredient into a dispersant according to the method of the present invention.

The invention has the beneficial effects that: according to the water reducer for the fabricated concrete member and the preparation method thereof, provided by the invention, the fluidity, slump retention and cohesiveness of concrete can be comprehensively improved through the preparation of the retarding water reducer and the matched use of the dispersing agent introduced in the use process of the water reducer.

Finally, it should be noted that the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited to the above-mentioned embodiment, but may be modified or some of the technical features thereof may be replaced by other technical solutions described in the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (6)

1. A water reducing agent for an assembled concrete member, characterized by: the preparation raw materials of the water reducer comprise unsaturated polyoxyethylene ether, crotonic anhydride, ethyl acrylate, 6-acrylamidocacetic acid and butyl glycolate, and the molar ratio is 1: (0.08-0.16): (0.15-0.35): (0.1-0.3): (0.2-0.4);

the molecular weight of the unsaturated polyoxyethylene ether is 400-2400, and the unsaturated polyoxyethylene ether is specifically allyl polyoxyethylene ether or isopentenyl polyoxyethylene ether;

the preparation of the water reducer for the fabricated concrete member specifically comprises the following steps:

(1) Heating 6-acrylamidocaaproic acid to 100-110 ℃, adding a catalyst, uniformly mixing, then dropwise adding butyl glycolate, and carrying out esterification reaction under the stirring condition of 110-120 ℃ for 5-6h to obtain an esterification product;

(2) Adding unsaturated polyoxyethylene ether, crotonic anhydride and deionized water into a reaction kettle, regulating the temperature of the reaction kettle to 70-80 ℃, respectively dropwise adding the esterified product obtained in the step (1), ethyl acrylate and an initiator aqueous solution, and stirring for reaction for 3-5h after the dropwise adding is finished, thus obtaining a finished product of the slow-release water reducer.

2. The water reducing agent for fabricated concrete members according to claim 1, wherein:

in the step (1), the catalyst is concentrated sulfuric acid, and the addition amount of the concentrated sulfuric acid is 1-2% of the total amount of reactants;

in the step (2), the initiator is one of azodiisobutyronitrile, benzoyl peroxide/N, N-dimethylaniline and tert-butyl hydroperoxide/sodium metabisulfite, and the mass ratio of the initiator to the unsaturated polyoxyethylene ether is (0.8-1.4): 100; the addition amount of deionized water is 50-80% of the total mass of polyoxyethylene ether and crotonic anhydride, and the mass ratio of the initiator to water in the initiator aqueous solution is 1: (2-4).

3. A method of using the water reducer for fabricated concrete components of claim 1, wherein: uniformly mixing the prepared water reducer with a dispersing agent, adding a cementing material and aggregate, adding mixing water, and fully stirring to obtain a material;

wherein the mixing amount of the water reducer and the dispersing agent is respectively 0.1-0.16% and 0.8-1.4% of the cementing material;

the active ingredients of the dispersing agent are amphoteric polymers, the preparation raw materials of the amphoteric polymers comprise vinyl ether, 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride, N, N, N-trimethyl-9-octadecene-1-ammonium chloride and oleic acid, and the molar ratio is 1: (0.1-0.3): (0.3-0.5): (0.4-0.7);

the preparation method of the amphoteric polymer comprises the following steps:

s1, mixing 3-carboxyl-N, N, N-trimethyl-2-propylene-1-ammonium chloride with deionized water to prepare a solution I, and mixing N, N, N-trimethyl-9-octadecene-1-ammonium chloride with deionized water to prepare a solution II;

s2, placing vinyl ether and oleic acid into a reaction kettle, adjusting the temperature of the reaction kettle to 80-90 ℃, respectively dropwise adding the solution I, the solution II and the aqueous solution of the initiator, and stirring for reaction for 4-6 hours after the dropwise adding is finished, thus obtaining the amphoteric polymer finished product.

4. A method of use according to claim 3, wherein:

in the step S1, the mass concentration of the first solution is 30-40%, and the mass concentration of the second solution is 50-60%;

the initiator in the step S2 is ammonium persulfate or benzoyl peroxide, and the mass ratio of the initiator to vinyl ether is (1-2): 100, the mass ratio of the initiator to water in the initiator aqueous solution is 1: (1-2).

5. A method for preparing a dispersant in a method for using a water reducing agent for fabricated concrete members according to claim 3 or 4, characterized in that: the method comprises the following specific steps: concentrating the prepared amphoteric polymer solution under reduced pressure, and vacuum drying at 40-50deg.C until the water content is less than or equal to 2% to obtain solid powder; mixing the obtained solid powder with starch and porous ceramic powder, dispersing in a dispersing machine of 1000-2000r/min, spraying sodium alginate material liquid, and drying to obtain the final product.

6. The method for producing a dispersant according to claim 5, wherein:

the sodium alginate material liquid comprises 10-20 parts of sodium alginate, 2-4 parts of talcum powder, 3-6 parts of phospholipid and 120-240 parts of deionized water;

the mass ratio of the solid powder to the starch to the porous ceramic powder is 1: (0.4-0.6): (10-18), and the spraying amount of the sodium alginate material liquid is 3-5%.