CN109749074B - Alkyl-containing viscosity-reducing polycarboxylate superplasticizer and preparation method and application thereof - Google Patents
Alkyl-containing viscosity-reducing polycarboxylate superplasticizer and preparation method and application thereof Download PDFInfo
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Abstract
The invention provides a viscosity reduction type active macromonomer, and also provides a viscosity reduction type polycarboxylate superplasticizer. The concrete doped with the product has low shrinkage rate and no cracking. The viscosity reduction hydrophobic group functional group is positioned on the side chain, the viscosity reduction effect of the water reducer can be adjusted through the content of the viscosity reduction functional group, but the content of the dispersing group is not influenced, the dispersing effect on cement particles is not influenced, and therefore the dispersing effect and the water reducing effect of the water reducer are not influenced.
Description
Technical Field
The invention relates to the technical field of concrete admixtures, in particular to an alkyl-containing viscosity-reducing polycarboxylic acid water reducer, and a preparation method and application thereof.
Background
In recent years, with the increase of the infrastructure of China, high-grade concrete gradually enters the building material market by virtue of the characteristics of high strength, good integrity and small self weight, and is particularly used in bridge engineering in large quantities. However, due to the adoption of a large amount of gel materials and a low water-gel ratio, the high-grade concrete has the problems of high viscosity and low flowing speed, so that the problems of concrete stirring, transportation, pumping and construction are caused, and the popularization and application of the high-strength and ultrahigh-strength concrete are limited to a great extent.
For engineering technicians, the problem of high viscosity of high-strength and ultrahigh-strength concrete is a long-standing technical problem. At present, the viscosity reduction method of high-strength concrete mainly adopts the steps of increasing the mixing amount of a water reducing agent and optimizing superfine powder to optimize the particle grading. The problems of bleeding, bottom scraping and the like of fresh concrete can occur when the mixing amount of the water reducing agent is increased and the viscosity of the concrete is reduced, so that certain difficulty is caused to construction, the concrete is excessively delayed to be coagulated, the formwork removal period is prolonged, and the production cost of the concrete is increased. Although many researches are carried out on the optimization of particle gradation by the optimized ultrafine powder to reduce the viscosity of concrete, the method has certain limitations, and the actual problem cannot be fundamentally solved by optimizing the particle gradation mainly depending on the strong adsorption and dispersion effects of the high-efficiency water reducing agent on the flowability of fresh concrete.
The polycarboxylic acid water reducing agent serving as a third-generation product of the concrete water reducing agent has the advantages of low mixing amount, high water reducing rate, good slump retaining performance, small shrinkage, environmental friendliness and the like, and becomes one of essential components of high-performance concrete. The high performance of the polycarboxylate-type water reducing agent is realized by selecting monomers with different structures and functions, setting the molecular structure of a specific polycarboxylate-type water reducing agent and optimally combining and controlling the polymerization degree of a main chain, the length of a side chain and the types of functional groups, and the polycarboxylate-type water reducing agent with low shrinkage and viscosity reduction functions is prepared and obtained, so that the problems of high concrete viscosity, low flowing speed, high shrinkage and the like are solved.
In recent years, viscosity-reducing polycarboxylic acid water reducing agents gradually become a research hotspot in the field of concrete admixtures, however, in the light of documents and patents of viscosity-reducing polycarboxylic acid water reducing agents, researchers mostly adopt (1) reducing the molecular weight of the water reducing agent, (2) reducing the length of PEG side chains, (3) introducing hydrophobic functional groups, such as methyl and ester groups, into the molecular structure of the water reducing agent, so as to increase the hydrophobicity of the product, thereby achieving the purposes of reducing the combination with water, releasing free water to the maximum extent, indirectly improving the water-cement ratio and further reducing the viscosity of concrete slurry. The molecular weight of the water reducing agent and the length of a PEG side chain are reduced, and the water reducing agent has the advantages that the viscosity reduction type water reducing agent has higher freedom of movement in free water than a common water reducing agent, and can extend molecular chains of the water reducing agent more quickly, so that cement particles are quickly adsorbed and dispersed, and the viscosity of cement paste is reduced. The disadvantages are that the molecular weight of the water reducing agent is small, and the absorption and dispersion group-COO-The quantity of the water reducing agent is small, the adsorption and dispersion effects of the water reducing agent molecules on cement particles are reduced, the length of PEG side chains is reduced, and the steric hindrance effect is reduced, so that the water reducing rate of the polycarboxylate water reducing agent is greatly reduced. Hydrophobic methyl and ester groups are introduced into the molecular structure of the water reducing agent, for example, methacrylate, hydroxy methacrylate and the like are introduced into the molecular structure, and the synthesized polymer has the characteristics ofA certain viscosity-reducing effect, but has the disadvantages that the hydrophobic functional group is positioned on the main chain, the content of the hydrophobic functional group is limited, and if the proportion of the hydrophobic polymerized small monomer in the copolymer for replacing methacrylic acid is too high, the dispersed group-COO is adsorbed-The content of (A) is reduced, the adsorption and dispersion of cement particles and hydration products thereof are influenced, the water reduction rate is reduced, and if the proportion of hydrophobic polymerized small monomers in the copolymer for substituting methacrylic acid is too low, the viscosity reduction effect is not obvious, and the aim of reducing the viscosity is not achieved. Therefore, the research and development of the polycarboxylic acid water reducing agent with good viscosity reduction effect and higher water reducing rate have important social and economic significance for the production and research and development of high-grade concrete, especially the production and research and development of ultrahigh-grade concrete with more than C100 and low-slump pipe pile concrete.
Disclosure of Invention
Aiming at the technical defects, the invention synthesizes PEG active macromonomer containing hydrophobic alkyl by ethylation reaction according to the design theory of a macromolecular structure, and the active macromonomer is copolymerized with acrylic acid and the like to synthesize the polycarboxylic acid water reducing agent. Because the hydrophobic alkyl is positioned on the side chain of PEG, the water reducer has the following 4 main advantages: 1. the content of the copolymer does not influence the adsorption and dispersion of-COO in the copolymer-The content of the groups does not influence the adsorption and dispersion effects of the water reducing agent; 2. the content of the hydrophobic alkyl can be adjusted at will according to the actual requirement of the viscosity reduction effect, so as to achieve the purpose of effectively solving the problems of high viscosity and low flow rate of high-grade concrete; 3. because the PEG side chain contains a large amount of hydrophobic viscosity-reducing alkyl groups, the water reducing agent molecules cannot form a complete water layer film on the surface of cement particles, but form a defective collapsed water layer film, and the defective collapsed water layer film endows the water reducing agent with the following characteristics: (1) more free water can be released, and the viscosity of cement paste is reduced; (2) the molecular weight of the water reducing agent is not limited by the viscosity reduction requirement; (3) the length of the PEG side face is not limited by the viscosity reduction requirement; 4. a large amount of hydrophobic alkyl is introduced into PEG side chain, so that the surface tension of the product is greatly reduced, and the contraction force of water evaporation is reduced, thereby reducing the contraction cracking of concrete and having good performanceReducing effect.
In order to realize the purpose, the technical scheme is as follows: the viscosity-reducing active macromonomer is a compound shown as a formula (I), wherein the compound shown as the formula (I) has the following structural formula:
wherein R is6H or CH3，R7＝CH2、CH2CH2Or OCH2CH2CH2CH2(ii) a m is an integer of 2 to 6, and x is an integer of 1 to 60. More preferably, x is an integer from 10 to 60.
The invention provides a preparation method of the viscosity-reducing active macromonomer, which comprises the following steps:
mixing an initiator enol and a catalyst, dropwise adding alkylene oxide at a constant speed of 80-120 ℃ in a protective gas atmosphere, continuously reacting for 6-12 hours at 90-110 ℃ after dropwise adding is finished within 2-4 hours, and obtaining a viscosity-reducing active macromonomer;
the structural formula of the alkylene oxide is shown as a formula (II),
The reaction formula is as follows:
preferably, the enol is at least one of allyl alcohol, methallyl alcohol, 4-hydroxybutyl vinyl ether and isopentenol, the catalyst is sodium hydride or sodium, and the protective gas is nitrogen.
Preferably, the molar ratio of the starter enol to the alkylene oxide is 1: 1 to 60. More preferably, the molar ratio of the starter enol to the alkylene oxide is 1: 10 to 60.
The invention provides a viscosity-reducing polycarboxylate superplasticizer which is a compound shown in a formula (III), wherein the structural formula of the compound shown in the formula (III) is as follows:
a is an integer of 10 to 80, b is an integer of 1 to 60, c is an integer of 1 to 80, d is an integer of 1 to 60,
a is
R1Is H or CH3；
B is
R2Is H or CH3，R3Is CH2、CH2CH2Or OCH2CH2CH2CH2，m1M is an integer of 0 to 502Is an integer of 5 to 50;
c is
R4Is H or CH3，R5Is CH2、CH2CH2Or OCH2CH2CH2CH2N is an integer of 1 to 80;
d is
R6Is H or CH3，R7Is CH2、CH2CH2Or OCH2CH2CH2CH2M is an integer of 2 to 6, and x is an integer of 1 to 60. More preferably, x is an integer from 10 to 60.
The invention provides a preparation method of the viscosity-reducing polycarboxylate superplasticizer, which comprises the following steps:
dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 to react under the condition of normal temperature, starting dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 within 2-3 h, dropwise adding the solution 3 for 10-30 min more than the solution 2, dropwise adding the solution 3 within 2.5-3.5 h, continuing to react for 4-8 h, and adjusting the pH of the reacted solution to 7-8 to obtain the viscosity-reducing polycarboxylic acid water reducer;
the reaction monomer A is at least one of acrylic acid and methacrylic acid;
the reaction monomer B is at least one of APEG/PPG, HAPEG/PPG, VAPEG/PPG and TAPEG/PPG;
the reaction monomer C is at least one of APEG, HPEG, VPEG and TPEG;
the reaction monomer D is the viscosity-reducing active macromonomer.
Preferably, the molar ratio of the reaction monomer A to the reaction monomer B to the reaction monomer C to the reaction monomer D is 4-10: 0.4-1.0: 0.6-1.2: 0.2 to 1.6.
Preferably, the addition amount of the chain transfer agent is 0.05-5% of the total mole number of the reaction monomers, the addition amount of the oxidant is 0.05-5% of the total mole number of the reaction monomers, and the addition amount of the reducing agent is 20-100% of the oxidant. The total reactive monomer moles refer to the sum of the moles of reactive monomer A, reactive monomer B, reactive monomer C and reactive monomer D.
Preferably, the oxidizing agent is hydrogen peroxide, the reducing agent is one or two of ascorbic acid and sodium bisulfite, and the chain transfer agent is one or two of thioglycolic acid and mercaptopropionic acid.
The invention provides application of the viscosity-reducing polycarboxylate superplasticizer in preparation of concrete.
The viscosity-reducing polycarboxylate superplasticizer is synthesized, and has remarkable viscosity-reducing and shrinkage-reducing effects while keeping a high water-reducing rate;
according to the invention, a PEG active macromonomer D containing alkyl hydrophobic functional groups is synthesized by using initiators such as prenol and alkyl epoxide, the macromonomer is copolymerized with a reactive monomer A, B, C to synthesize a polycarboxylic acid water reducing agent, the hydrophobic alkyl functional groups are positioned on side chains, and the content of the hydrophobic alkyl functional groups in the whole molecular structure can be randomly adjusted according to the actual requirement of the viscosity reduction effect under the condition of not influencing the water reduction rate, so that the requirement on the viscosity reduction effect is met, and the technical defect that the content of the hydrophobic functional groups influences the water reduction rate in the prior art is avoided; meanwhile, because a large amount of hydrophobic alkyl groups are introduced into PEG side chains of the water reducing agent, water reducing agent molecules cannot form a complete water layer film on the surface of cement particles, but form a defective collapsed water layer film, and the defective collapsed water layer film endows the water reducing agent with the following characteristics: (1) more free water can be released, and the viscosity of cement paste is reduced; (2) the molecular weight of the water reducing agent is not limited by the viscosity reduction requirement; (3) the PEG side chain of the water reducer molecule is not limited by viscosity reduction requirements, and the technical defect that the water reduction rate of the product is influenced by reducing the polymer molecular weight and the PEG side chain of the viscosity reduction type polycarboxylate water reducer for realizing the viscosity reduction effect in the prior art is overcome.
On the other hand, in the molecular structure of the water reducing agent, the PPG chain segment with hydrophobic effect introduced in the side chain and a large amount of hydrophobic alkyl functional groups introduced by the macromonomer D endow the synthesized water reducing agent with good capability of reducing surface tension, reduce the contractility of water evaporation and further reduce the shrinkage cracking of concrete.
Has the advantages that:
compared with the viscosity reduction type polycarboxylate superplasticizer synthesized by the prior art, the viscosity reduction type polycarboxylate superplasticizer synthesized by the method disclosed by the invention has the following advantages that the components and functional groups have mutual synergistic effect:
1. the viscosity-reducing hydrophobic group functional group is positioned on the side chain, the viscosity-reducing effect of the water reducer can be adjusted by adjusting the content of the viscosity-reducing functional group, but the content of the dispersing group and the dispersing effect on cement particles are not influenced, so that the dispersing and water-reducing effects of the water reducer are not influenced;
2. the molecular weight of the water reducing agent is not limited by the viscosity reduction effect of the water reducing agent;
3. the length of the PEG side chain in the molecular structure of the water reducing agent is not limited by the viscosity reduction effect of the water reducing agent;
4. the viscosity reduction effect is excellent, and the water reduction rate is not influenced.
5. Has better adaptability to cement.
6. Has good viscosity reduction effect.
7. Has good water reducing rate and slump retaining capacity
8. The concrete with the product has low shrinkage rate and no cracking.
Detailed Description
To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples.
Example 1
The preparation method of the viscosity-reducing polycarboxylate superplasticizer comprises the following steps:
(1) and (3) synthesizing a viscosity-reducing active macromonomer D:
1mol of methallyl alcohol and 2g of sodium hydride are added into a four-neck glass flask with a stirrer, a thermometer, a reflux condenser tube and a dropping device, stirred under the protection of nitrogen, 1mol of alkylene oxide is dropped at a constant speed at 80 ℃, after dropping for 2h, the reaction is continued for 6h at 90 ℃ to obtain the viscosity-reducing active macromonomer D.
(2) Synthesis of viscosity-reducing polycarboxylic acid water reducer
Dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 to react under the normal temperature condition, starting dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 within 3h, dropwise adding the solution 3 for 30min more than the solution 2, dropwise adding within 3.5h, continuing to react for 6h, and adjusting the pH of the reacted solution to 7 to obtain the viscosity-reducing polycarboxylic acid water reducer.
The reaction monomer A is methacrylic acid, the reaction monomer B is HPEG/PPG, the reaction monomer C is HPEG, and the reaction monomer D is the viscosity-reducing active macromonomer D obtained in the step (1). The molar ratio of the reaction monomer A to the reaction monomer B to the reaction monomer C to the reaction monomer D is 6:0.8: 1.
the oxidant is hydrogen peroxide, the reducing agent is sodium bisulfite, and the chain transfer agent is thioglycolic acid. The adding amount of the chain transfer agent is 2 percent of the total mole number of the reaction monomers, the adding amount of the oxidizing agent is 2 percent of the total mole number of the reaction monomers, and the adding amount of the reducing agent is 80 percent of the oxidizing agent.
Example 2
The preparation method of the viscosity-reducing polycarboxylate superplasticizer comprises the following steps:
(1) and (3) synthesizing a viscosity-reducing active macromonomer D:
1mol of methallyl alcohol and 2g of sodium hydride are added into a four-neck glass flask with a stirrer, a thermometer, a reflux condenser tube and a dropping device, the mixture is stirred under the protection of nitrogen, 10mol of alkylene oxide is dropped at a constant speed at 90 ℃, the dropping is completed within 3 hours, and the reaction continues for 8 hours at 100 ℃ to obtain the viscosity-reducing active macromonomer D.
(2) Synthesis of viscosity-reducing polycarboxylic acid water reducer
Dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 to react under the normal temperature condition, starting dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 within 3h, dropwise adding the solution 3 for 30min more than the solution 2, dropwise adding within 3.5h, continuing to react for 6h, and adjusting the pH of the reacted solution to 7 to obtain the viscosity-reducing polycarboxylic acid water reducer.
The reaction monomer A is methacrylic acid, the reaction monomer B is HPEG/PPG, the reaction monomer C is HPEG, and the reaction monomer D is the viscosity-reducing active macromonomer D obtained in the step (1). The molar ratio of the reaction monomer A to the reaction monomer B to the reaction monomer C to the reaction monomer D is 6:0.8: 1.
the oxidant is hydrogen peroxide, the reducing agent is sodium bisulfite, and the chain transfer agent is thioglycolic acid. The adding amount of the chain transfer agent is 2 percent of the total mole number of the reaction monomers, the adding amount of the oxidizing agent is 2 percent of the total mole number of the reaction monomers, and the adding amount of the reducing agent is 80 percent of the oxidizing agent.
Example 3
The preparation method of the viscosity-reducing polycarboxylate superplasticizer comprises the following steps:
(1) and (3) synthesizing a viscosity-reducing active macromonomer D:
1mol of methallyl alcohol and 2g of sodium hydride are added into a four-neck glass flask with a stirrer, a thermometer, a reflux condenser tube and a dropping device, stirred under the protection of nitrogen, 30mol of alkylene oxide is dropped at a uniform speed at 110 ℃, after dropping for 3h, reaction is continued for 10h at 100 ℃, and the viscosity-reducing active macromonomer D is obtained.
(2) Synthesis of viscosity-reducing polycarboxylic acid water reducer
Dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 to react under the normal temperature condition, starting dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 within 3h, dropwise adding the solution 3 for 30min more than the solution 2, dropwise adding within 3.5h, continuing to react for 6h, and adjusting the pH of the reacted solution to 7 to obtain the viscosity-reducing polycarboxylic acid water reducer.
The reaction monomer A is methacrylic acid, the reaction monomer B is HPEG/PPG, the reaction monomer C is HPEG, and the reaction monomer D is the viscosity-reducing active macromonomer D obtained in the step (1). The molar ratio of the reaction monomer A to the reaction monomer B to the reaction monomer C to the reaction monomer D is 6:0.8: 1.
the oxidant is hydrogen peroxide, the reducing agent is sodium bisulfite, and the chain transfer agent is thioglycolic acid. The adding amount of the chain transfer agent is 2 percent of the total mole number of the reaction monomers, the adding amount of the oxidizing agent is 2 percent of the total mole number of the reaction monomers, and the adding amount of the reducing agent is 80 percent of the oxidizing agent.
Example 4
The preparation method of the viscosity-reducing polycarboxylate superplasticizer comprises the following steps:
(1) and (3) synthesizing a viscosity-reducing active macromonomer D:
1mol of methallyl alcohol and 2g of sodium hydride are added into a four-neck glass flask with a stirrer, a thermometer, a reflux condenser tube and a dropping device, stirred under the protection of nitrogen, 60mol of alkylene oxide is dropped at 120 ℃ at a constant speed, the dropping is completed within 4h, and the reaction is continued for 12h at 110 ℃ to obtain the viscosity-reducing active macromonomer D.
(2) Synthesis of viscosity-reducing polycarboxylic acid water reducer
Dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 to react under the normal temperature condition, starting dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 within 3h, dropwise adding the solution 3 for 30min more than the solution 2, dropwise adding within 3.5h, continuing to react for 6h, and adjusting the pH of the reacted solution to 7 to obtain the viscosity-reducing polycarboxylic acid water reducer.
The reaction monomer A is methacrylic acid, the reaction monomer B is HPEG/PPG, the reaction monomer C is HPEG, and the reaction monomer D is the viscosity-reducing active macromonomer D obtained in the step (1). The molar ratio of the reaction monomer A to the reaction monomer B to the reaction monomer C to the reaction monomer D is 6:0.8: 1.
the oxidant is hydrogen peroxide, the reducing agent is sodium bisulfite, and the chain transfer agent is thioglycolic acid. The adding amount of the chain transfer agent is 2 percent of the total mole number of the reaction monomers, the adding amount of the oxidizing agent is 2 percent of the total mole number of the reaction monomers, and the adding amount of the reducing agent is 80 percent of the oxidizing agent.
Example 5
The preparation method of the viscosity-reducing polycarboxylate superplasticizer comprises the following steps:
(1) and (3) synthesizing a viscosity-reducing active macromonomer D:
1mol of allyl alcohol and 2g of sodium hydride are added into a four-neck glass flask with a stirrer, a thermometer, a reflux condenser tube and a dropping device, stirred under the protection of nitrogen, 30mol of alkylene oxide is dropped at a uniform speed at 110 ℃, after dropping for 3h, reaction is continued for 10h at 100 ℃ to obtain the viscosity-reducing active macromonomer D.
(2) Synthesis of viscosity-reducing polycarboxylic acid water reducer
Dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 to react under the normal temperature condition, starting dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 within 3h, dropwise adding the solution 3 for 30min more than the solution 2, dropwise adding within 3.5h, continuing to react for 6h, and adjusting the pH of the reacted solution to 7 to obtain the viscosity-reducing polycarboxylic acid water reducer.
The reaction monomer A is methacrylic acid, the reaction monomer B is APEG/PPG, the reaction monomer C is HPEG, and the reaction monomer D is the viscosity-reducing active macromonomer D obtained in the step (1). The molar ratio of the reaction monomer A to the reaction monomer B to the reaction monomer C to the reaction monomer D is 6:0.8: 1.
the oxidant is hydrogen peroxide, the reducing agent is sodium bisulfite, and the chain transfer agent is thioglycolic acid. The adding amount of the chain transfer agent is 2 percent of the total mole number of the reaction monomers, the adding amount of the oxidizing agent is 2 percent of the total mole number of the reaction monomers, and the adding amount of the reducing agent is 80 percent of the oxidizing agent.
Example 6
Parameters of examples 1 to 5 of the invention are shown in Table 1, concrete was prepared by using the viscosity-reducing polycarboxylic acid water-reducing agent synthesized in examples 1 to 5 of the invention, and a commercially available viscosity-reducing polycarboxylic acid water-reducing agent was used as a comparative example. Then, the concrete was prepared in the ratio shown in Table 2, and the properties of the concrete were measured.
TABLE 1 parameters of examples 1 to 5 of the present invention
TABLE 2 concrete mix proportion (C80)
The admixture of the present invention was a mixture (solid content: 20%) of the viscosity-reducing type polycarboxylic acid water-reducing agent of examples 1 to 5 and a conventional water-reducing type polycarboxylic acid water-reducing agent (weight ratio: 60: 40).
The admixture of the comparative example was a mixture (20% in solid content) of a commercially available viscosity-reducing type polycarboxylic acid water-reducing agent and a conventional water-reducing type polycarboxylic acid water-reducing agent (60: 40 by weight).
The concrete prepared by the viscosity-reducing polycarboxylate superplasticizers of embodiments 1-5 of the invention and the commercially available viscosity-reducing polycarboxylate superplasticizers has the following effects:
TABLE 3 concrete Effect
As can be seen from Table 3, the concrete doped with the viscosity-reducing polycarboxylic acid water reducer of the invention has better dispersibility, higher water-reducing rate, lower viscosity, better fluidity and smaller shrinkage reduction rate of hardened concrete compared with the concrete doped with the commercial viscosity-reducing polycarboxylic acid water reducer along with the increase of PEG polymerization degree in the viscosity-reducing macromonomer D in the molecular structure of the water reducer. The test results can be explained according to the theoretical model of the invention as follows:
the viscosity of the cement paste depends on the thickness of the water film layer on the surface of the cement particles, which in turn depends on the initial water addition and the water content entrapped in the flocs. In order to improve the strength of high-grade concrete, under the condition of low water-cement ratio, more free water is released mainly by virtue of the adsorption and dispersion effects of an additive and reduction of bound water, and on the basis of the theory, the theoretical model of the invention is as follows:
the hydrophobic alkyl is positioned on the PEG side chain, so that the hydrophilicity of the PEG side chain is reduced, the hydrophobicity of the PEG side chain is improved, and due to the existence of a large number of hydrophobic groups, water reducing agent molecules cannot form a complete water layer film on the surface of cement particles, but form a defective collapsed water layer film, so that more free water can be released, the viscosity of cement paste is greatly reduced, the surface tension of the water reducing agent is reduced, the contraction force of water evaporation is reduced, the contraction cracking of concrete is reduced, a good contraction reducing effect is achieved, and the compressive strength of the concrete is improved.
The best results are obtained in example 4.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (9)
1. The viscosity-reducing polycarboxylate superplasticizer is characterized by being a compound shown in a formula (III), wherein the compound shown in the formula (III) has the following structural formula:
a is an integer of 10 to 80, b is an integer of 1 to 60, c is an integer of 1 to 80, d is an integer of 1 to 60,
a is
R1Is H or CH3；
B is
R2Is H or CH3，R3Is CH2、CH2CH2Or OCH2CH2CH2CH2，m1M is an integer of 0 to 502Is an integer of 5 to 50;
c is
R4Is H or CH3，R5Is CH2、CH2CH2Or OCH2CH2CH2CH2N is an integer of 1 to 80;
d is
R6Is H or CH3，R7Is CH2、CH2CH2Or OCH2CH2CH2CH2M is an integer of 2 to 6, and x is an integer of 1 to 60;
dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 for reaction under the normal temperature condition, dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 over 2-3 h, dropwise adding the solution 3 for 10-30 min more than the solution 2, dropwise adding over 2.5-3.5 h, continuing to react for 4-8 h, adjusting the pH of the reacted solution to 7-8, and thus obtaining the viscosity-reducing polycarboxylic acid water reducer;
the reaction monomer A is at least one of acrylic acid and methacrylic acid;
the reaction monomer B is at least one of APEG/PPG, HPEG/PPG, VPEG/PPG and TPEG/PPG;
the reaction monomer C is at least one of APEG, HPEG, VPEG and TPEG;
the reactive monomer D is a compound shown in a formula (I), and the structural formula of the compound shown in the formula (I) is as follows:
wherein R is6H or CH3，R7＝CH2、CH2CH2Or OCH2CH2CH2CH2(ii) a m is an integer of 2-6, and x is an integer of 1-60;
the preparation method of the reactive monomer D comprises the following steps:
mixing an initiator enol and a catalyst, dropwise adding alkylene oxide at a constant speed of 80-120 ℃ in a protective gas atmosphere, continuously reacting for 6-12 hours at 90-110 ℃ after dropwise adding is finished within 2-4 hours, and obtaining a viscosity-reducing active macromonomer;
the structural formula of the alkylene oxide is shown as a formula (II),
2. The preparation method of the viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized by comprising the following steps:
dissolving a reaction monomer B, a reaction monomer C, a reaction monomer D and an oxidant in water to obtain a solution 1, dissolving a reaction monomer A and a chain transfer agent in water to obtain a solution 2, dissolving a reducing agent in water to obtain a solution 3, dropwise adding the solution 2 and the solution 3 into the solution 1 to react under the condition of normal temperature, starting dropwise adding the solution 2 and the solution 3 simultaneously, dropwise adding the solution 2 within 2-3 h, dropwise adding the solution 3 for 10-30 min more than the solution 2, dropwise adding the solution 3 within 2.5-3.5 h, continuing to react for 4-8 h, and adjusting the pH of the reacted solution to 7-8 to obtain the viscosity-reducing polycarboxylic acid water reducer;
the reaction monomer A is at least one of acrylic acid and methacrylic acid;
the reaction monomer B is at least one of APEG/PPG, HPEG/PPG, VPEG/PPG and TPEG/PPG;
the reaction monomer C is at least one of APEG, HPEG, VPEG and TPEG;
the reactive monomer D is a compound shown in a formula (I), and the structural formula of the compound shown in the formula (I) is as follows:
wherein R is6H or CH3，R7＝CH2、CH2CH2Or OCH2CH2CH2CH2(ii) a m is an integer of 2 to 6, and x is an integer of 1 to 60.
3. The method according to claim 2, wherein the method for preparing the reactive monomer D comprises the steps of:
mixing an initiator enol and a catalyst, dropwise adding alkylene oxide at a constant speed of 80-120 ℃ in a protective gas atmosphere, continuously reacting for 6-12 hours at 90-110 ℃ after dropwise adding is finished within 2-4 hours, and obtaining a viscosity-reducing active macromonomer;
the structural formula of the alkylene oxide is shown as a formula (II),
4. The production method according to claim 3, wherein the alkenyl alcohol is at least one of allyl alcohol, isobutenol, 4-hydroxybutyl vinyl ether and isopentenyl alcohol, the catalyst is sodium hydride or sodium, and the protective gas is nitrogen.
5. The process according to claim 3, wherein the molar ratio of the starter enol to the alkylene oxide is from 1: 1 to 60.
6. The preparation method according to claim 2, wherein the molar ratio of the reactive monomer A to the reactive monomer B to the reactive monomer C to the reactive monomer D is 4-10: 0.4-1.0: 0.6-1.2: 0.2 to 1.6.
7. The preparation method according to claim 2, wherein the addition amount of the chain transfer agent is 0.05 to 5% of the total mole number of the reaction monomers, the addition amount of the oxidizing agent is 0.05 to 5% of the total mole number of the reaction monomers, and the addition amount of the reducing agent is 20 to 100% of the oxidizing agent.
8. The preparation method according to claim 2, wherein the oxidizing agent is hydrogen peroxide, the reducing agent is one or both of ascorbic acid and sodium bisulfite, and the chain transfer agent is one or both of thioglycolic acid and mercaptopropionic acid.
9. The use of the viscosity-reducing polycarboxylate superplasticizer according to claim 1 for preparing concrete.
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| CN106471022A (en) * | 2014-07-09 | 2017-03-01 | 巴斯夫欧洲公司 | Reactive monomer as the comonomer producing polymer |
| CN108003301A (en) * | 2017-11-14 | 2018-05-08 | 佳化化学（茂名）有限公司 | A kind of preparation method of viscosity reduction type polycarboxylate water-reducer |
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| CN106471022A (en) * | 2014-07-09 | 2017-03-01 | 巴斯夫欧洲公司 | Reactive monomer as the comonomer producing polymer |
| CN104292451A (en) * | 2014-10-15 | 2015-01-21 | 南京红宝丽股份有限公司 | Preparation method and application of unsaturated polyether |
| CN108003301A (en) * | 2017-11-14 | 2018-05-08 | 佳化化学（茂名）有限公司 | A kind of preparation method of viscosity reduction type polycarboxylate water-reducer |
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