Alkali-free fluoride-free liquid accelerator and preparation method thereof

Abstract

The invention provides an alkali-free fluorine-free liquid accelerator and a preparation method thereof, the alkali-free fluorine-free liquid accelerator comprises the following components: soluble aluminum salt, a dispersant, a pH regulator, an early strength agent, polymeric alcohol amine and water, and the polymeric alcohol amine is obtained by polymerization reaction of an acrylate monomer, a polyamine monomer and an alkyl ethylene oxide monomer. According to the accelerator, the complexing ability to aluminum ions is improved by introducing polymeric alcohol amine, so that the solubility and the stability of the aluminum ions are improved, meanwhile, the solubility of amide groups can be improved by hydrophilic groups in chain segments of the polymeric alcohol amine, the setting time of concrete is shortened, and the early strength of the concrete is improved.

Description

Technical Field

[0001] The invention relates to the technical field of cement concrete accelerating agent, in particular to an alkali-free and fluorine-free liquid accelerating agent and a preparation method thereof. Background Art

[0002] Shotcrete is widely used in many fields such as tunnel engineering, slope support, and bridge construction. Accelerators have become one of the indispensable admixtures for shotcrete due to their excellent characteristics of rapid setting and early strength. Traditional powdered accelerators are very harmful to the health of construction workers due to the large amount of dust during construction. Alkaline accelerators have a high alkali content, and alkali-aggregate reaction will occur in the later stage, which seriously affects the later strength of concrete. The increase in aluminum ion content helps to increase the coagulation and hardening speed of cement-based materials. In the process of preparing accelerators, in order to improve the solubility of aluminum ions, highly toxic and highly corrosive hydrofluoric acid is sometimes used, which causes great harm to construction workers and is very unfavorable to environmental protection. In addition, if suspending agents such as magnesium fluorosilicate are used for solubilization, it is difficult to maintain stability for a long time, and the accelerator solution is thick and difficult to construct. Therefore, in order to ensure the safety of shotcrete construction and the quality of the project, the research and development of high-performance alkali-free and fluorine-free liquid accelerators is particularly important. Although alkali-free and fluorine-free liquid accelerators have become a research hotspot in the field of concrete admixtures, there are still many problems in their preparation and application. The biggest difficulty in alkali-free and fluorine-free liquid accelerators with aluminum sulfate as the main accelerating component is to overcome the short-term instability problem caused by poor solubility due to the easy hydrolysis and polymerization of aluminum sulfate. How to obtain a liquid alkali-free accelerator with high aluminum ion concentration, excellent stability and low cost has become a problem that needs to be solved urgently.

[0003] Alcoholamine is a good complexing agent for aluminum ions and can increase the solubility of aluminum ions. For example, the formula of the low-viscosity and easy-pump fluorine-free and alkali-free liquid accelerator disclosed in patent CN118545936A includes diethanolamine; the alkali-free liquid accelerator disclosed in patent CN118529964A includes triethanolamine; the formula of the ultra-early strength fluorine-free and alkali-free liquid accelerator disclosed in patent CN113603384A includes an organic solubilizing agent, and the organic solubilizing agent includes low-molecular alcoholamine; however, the low-molecular alcoholamine added to these formulas will affect the later strength of concrete, thereby affecting the use effect of the accelerator. Summary of the invention

[0004] The invention provides an alkali-free and fluorine-free liquid accelerating setting agent and a preparation method thereof. The accelerating setting agent improves the complexing ability of aluminum ions by introducing polyolamine, thereby improving the solubility and stability of aluminum ions. At the same time, the hydrophilic groups in the polyolamine chain segments can improve the solubility of the amide groups, shorten the setting time of concrete, and improve the early strength of concrete.

[0005] The technical solution adopted to achieve the above-mentioned purpose of the present invention is:

[0006] An alkali-free and fluorine-free liquid accelerating setting agent, wherein the components and mass ratios of the alkali-free and fluorine-free liquid accelerating setting agent are:

[0007] Soluble aluminum salt 30-50%

[0008]

[0009] The polymerized alcohol amine is obtained by polymerization reaction of acrylate monomer, polyamine monomer and alkylethylene oxide monomer.

[0010] The preparation method of the polymeric alcohol amine comprises the following steps:

[0011] (1) Adding acrylate monomer, polyamine monomer and catalyst A into a reaction kettle, heating to 60-130° C., reacting for 2-5 hours, and obtaining an amide compound; wherein the molar ratio of acrylate to polyamine is 1:(1-5), and the mass ratio of catalyst A to the total reactants is 1:(50-100);

[0012] (2) adding catalyst B and the amide compound obtained in step (1) into a reaction kettle, replacing the atmosphere with nitrogen, heating to 80-120° C., vacuum dehydrating, and then adding an alkylethylene oxide monomer to carry out a polymerization reaction. The polymerization reaction temperature is controlled at 80-120° C., reacting for 10-60 minutes, and cooling to room temperature to obtain an unsaturated alcohol amine; wherein the molar ratio of the amide compound to the alkylethylene oxide monomer is 1:(1-3), and the mass ratio of the catalyst B to the total reactant is 1:(50-100);

[0013] (3) taking the unsaturated alcohol amine obtained in step (2) and adding it into a reaction kettle, adding a certain amount of an oxidant, and starting to dropwise add a solution consisting of a reducing agent, a chain transfer agent and deionized water for 2 to 4 hours, and keeping the temperature for 1 to 2 hours after the dropwise addition is completed, so as to obtain a polymerized alcohol amine; wherein the molar ratio of the oxidant to the unsaturated alcohol amine is (2 to 5):100, the molar ratio of the reducing agent to the unsaturated alcohol amine is (0.1 to 1):100, and the molar ratio of the chain transfer agent to the unsaturated alcohol amine is (1 to 5):100.

[0014] Preferably, the acrylic acid ester monomer is at least one of methyl acrylate, ethyl acrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.

[0015] Preferably, the polyamine monomer is at least one of ethylenediamine, propylenediamine, tetraethylenepentamine and diethylenetriamine.

[0016] Preferably, the alkylethylene oxide monomer is at least one of ethylene oxide, propylene oxide and butylene oxide.

[0017] Preferably, the catalyst A is at least one of concentrated sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid; and the catalyst B is at least one of potassium oxide, sodium hydroxide, potassium hydroxide, potassium hydride, sodium hydride, potassium methoxide, or sodium methoxide.

[0018] Preferably, the oxidant is at least one of peracetic acid, hydrogen peroxide, benzoyl peroxide, potassium persulfate, ammonium persulfate, and sodium persulfate; the reducing agent is at least one of bleaching agent, sodium bisulfite, sodium pyrosulfite, ferrous sulfate, ferrous pyrophosphate, sodium hypophosphite, and L-ascorbic acid; the chain transfer agent is at least one of thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptoethanol, mercaptopropanol, sodium methyl methacrylate sulfonate, dodecyl mercaptan, undecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, sodium hypophosphite, isopropyl alcohol, trisodium phosphate, sodium formate, and sodium acetate.

[0019] Preferably, the soluble aluminum salt is at least one of sodium aluminate, anhydrous aluminum sulfate, polyaluminum sulfate, and aluminum sulfate 18hydrate.

[0020] Preferably, the dispersant is any one of hydrated magnesium silicate, polyethylene glycol and polyacrylamide; the pH adjuster is at least one of phosphoric acid, ethylenediaminetetraacetic acid, oxalic acid, acetic acid, citric acid and methacrylic acid; and the early strength agent is at least one of lithium carbonate, urea and calcium nitrate.

[0021] The present invention also provides a method for preparing an alkali-free and fluorine-free liquid accelerating setting agent, comprising the following steps: adding water into a reaction kettle, heating to 60-80°C, sequentially adding a soluble aluminum salt, a dispersant, an early strength agent and a polymeric alcohol amine, keeping the temperature for reaction for 1-2 hours, adding a pH regulator, adjusting the pH to 6-8, and obtaining an alkali-free and fluorine-free liquid accelerating setting agent.

[0022] Compared with the prior art, the alkali-free and fluorine-free liquid quick-setting agent provided by the present invention has the following advantages: the present invention carries out amidation reaction between acrylic acid ester and polyamine, then forms alcohol amine through ring-opening polymerization with epoxy compound, and then forms polymeric alcohol amine through polymerization reaction of unsaturated double bonds; the complexing ability for aluminum ions can be greatly increased by introducing a large number of amide groups and alcohol amine groups, and the solubility and stability of aluminum ions can be improved; at the same time, the solubility of amide groups can be improved by utilizing hydrophilic groups in chain segments, thereby shortening the setting time of concrete and improving the early strength of concrete. DETAILED DESCRIPTION

[0023] The following examples describe the alkali-free and fluorine-free liquid quick-setting agent and its preparation method in more detail, and these examples are given in an illustrative manner so that technicians familiar with this project can understand the content of the present invention and implement it, but these examples do not limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be included in the protection scope of the present invention.

[0024] Example 1

[0025] The preparation method of the polyolamine in the present embodiment comprises the following steps:

[0026] (1) In a four-necked flask equipped with a thermometer, a stirring device, and a condenser reflux tube, 86.1 g (1 mol) of methyl acrylate, 120.2 g (2 mol) of ethylenediamine, and 2.5 g of concentrated sulfuric acid were added, heated to 95° C., and reacted for 4 h to obtain an amide compound;

[0027] (2) Add 3 g of sodium methoxide and 104 g (1 mol) of an amide compound to a high-pressure reactor, replace with nitrogen, heat to 95° C., dehydrate under vacuum, then add 88.1 g (2 mol) of ethylene oxide to carry out polymerization reaction, control the polymerization reaction temperature to 90° C., react for 50 min, and cool to room temperature to obtain an unsaturated alcohol amine;

[0028] (3) 148 g (1 mol) of the obtained unsaturated alcohol amine was added to a reaction kettle, and 1.52 g of peracetic acid (0.02 mol) was added, and a solution consisting of 0.46 g (0.003 mol) of bleaching powder, 2.76 g (0.03 mol) of thioglycolic acid and 50 g of deionized water was added dropwise for 3 h. After the addition was completed, the mixture was kept warm for 1 h to obtain polymeric alcohol amine A.

[0029] The preparation method of the alkali-free and fluorine-free liquid accelerating setting agent in this embodiment comprises the following steps: adding 250 g of deionized water into a reaction kettle, heating to 60° C., sequentially adding 450 g of polyaluminum sulfate, 35 g of hydrated magnesium silicate, 20 g of lithium carbonate and 50 g of polyolamine A, keeping the temperature for reaction for 1 hour, adding 10.2 g of phosphoric acid, adjusting the pH to 7, and obtaining the alkali-free and fluorine-free liquid accelerating setting agent A.

[0030] Example 2

[0031] The preparation method of the polyolamine in the present embodiment comprises the following steps:

[0032] (1) In a four-necked flask equipped with a thermometer, a stirring device, and a condenser reflux tube, 100.1 g (1 mol) of ethyl acrylate, 222.3 g (3 mol) of propylene diamine, and 4.2 g of p-toluenesulfonic acid were added, heated to 105° C., and reacted for 3.5 h to obtain an amide compound;

[0033] (2) Add 3.5 g of sodium hydroxide and 118 g (1 mol) of an amide compound to a high-pressure reactor, replace with nitrogen, heat to 105° C., dehydrate under vacuum, then add 174.2 g (3 mol) of propylene oxide to carry out polymerization reaction, control the polymerization reaction temperature at 105° C., react for 40 min, and cool to room temperature to obtain an unsaturated alcohol amine;

[0034] (3) 176 g (1 mol) of the obtained unsaturated alcohol amine was added to a reaction kettle, and 4.95 g of 27.5% hydrogen peroxide (0.04 mol) was added, and a solution consisting of 0.52 g (0.005 mol) of sodium bisulfite, 2.12 g (0.02 mol) of 3-mercaptopropionic acid and 50 g of deionized water was added dropwise for 2.5 h. After the addition was completed, the mixture was kept warm for 1.5 h to obtain polymeric alcohol amine B.

[0035] The preparation method of the alkali-free and fluorine-free liquid accelerating setting agent in this embodiment comprises the following steps: adding 300 g of deionized water into a reaction kettle, heating to 65° C., adding 500 g of aluminum sulfate 18hydrate, 50 g of polyethylene glycol, 40 g of calcium nitrate and 60 g of polyolamine B in sequence, keeping the temperature for reaction for 1.5 h, adding 12.6 g of ethylenediaminetetraacetic acid, adjusting the pH to 7, and obtaining the alkali-free and fluorine-free liquid accelerating setting agent B.

[0036] Example 3

[0037] The preparation method of the polyolamine in the present embodiment comprises the following steps:

[0038] (1) In a four-necked flask equipped with a thermometer, a stirring device, and a condenser reflux tube, 116.1 g (1 mol) of hydroxyethyl acrylate, 283.9 g (1.5 mol) of tetraethylenepentamine, and 6 g of hydrochloric acid were added, heated to 75° C., and reacted for 3 h to obtain an amide compound;

[0039] (2) Add 5.6 g of potassium hydroxide and 243 g (1 mol) of an amide compound to a high-pressure reactor, replace with nitrogen, heat to 85° C., dehydrate under vacuum, then add 144.2 g (2 mol) of butylene oxide to carry out polymerization reaction, control the polymerization reaction temperature to 85° C., react for 30 min, and cool to room temperature to obtain an unsaturated alcohol amine;

[0040] (3) 315 g (1 mol) of the obtained unsaturated alcohol amine was added to a reaction kettle, and 12.1 g of benzoyl peroxide (0.05 mol) was added. A solution consisting of 1.23 g (0.007 mol) of L-ascorbic acid, 3.12 g (0.04 mol) of mercaptoethanol and 50 g of deionized water was added dropwise for 2 h. After the addition was completed, the mixture was kept warm for 2 h to obtain polymeric alcohol amine C.

[0041] The preparation method of the alkali-free and fluorine-free liquid accelerating setting agent in this embodiment comprises the following steps: adding 400 g of deionized water into a reaction kettle, heating to 70° C., adding 400 g of anhydrous aluminum sulfate, 45 g of polyacrylamide, 30 g of urea and 40 g of polyolamine C in sequence, keeping the temperature for reaction for 2 h, adding 8.3 g of citric acid, adjusting the pH to 7, and obtaining the alkali-free and fluorine-free liquid accelerating setting agent C.

[0042] Example 4

[0043] The preparation method of the polyolamine in the present embodiment comprises the following steps:

[0044] (1) In a four-necked flask equipped with a thermometer, a stirring device, and a condenser reflux tube, 130.1 g (1 mol) of hydroxypropyl acrylate, 103.2 g (1 mol) of diethylenetriamine, and 3 g of concentrated sulfuric acid were added, heated to 120° C., and reacted for 2 h to obtain an amide compound;

[0045] (2) Add 3.5 g of potassium hydroxide and 157 g (1 mol) of an amide compound to a high-pressure reactor, replace with nitrogen, heat to 110° C., dehydrate under vacuum, then add 66.1 g (1.5 mol) of ethylene oxide to carry out polymerization reaction, control the polymerization reaction temperature to 110° C., react for 60 min, and cool to room temperature to obtain an unsaturated alcohol amine;

[0046] (3) 201 g (1 mol) of the obtained unsaturated alcohol amine was added to a reaction kettle, and 6.84 g of ammonium persulfate (0.03 mol) was added. A solution consisting of 0.88 g (0.01 mol) of sodium hypophosphite, 10.12 g (0.05 mol) of dodecyl mercaptan and 50 g of deionized water was added dropwise for 3 h. After the addition was completed, the mixture was kept warm for 2 h to obtain polymeric alcohol amine D.

[0047] The preparation method of the alkali-free and fluorine-free liquid accelerating setting agent in this embodiment comprises the following steps: adding 500 g of deionized water into a reaction kettle, heating to 80° C., adding 400 g of sodium aluminate, 40 g of hydrated magnesium silicate, 50 g of calcium nitrate and 80 g of polyolamine D in sequence, keeping the temperature for reaction for 1 hour, adding 15.8 g of acetic acid, adjusting the pH to 7, and obtaining the alkali-free and fluorine-free liquid accelerating setting agent D.

[0048] Comparative Example 1

[0049] The preparation method of the accelerator in this comparative example is basically the same as that in Example 2, the only difference being that triethanolamine is used instead of the polymeric alcohol amine B.

[0050] Comparative Example 2

[0051] The preparation method of the accelerator in this comparative example is basically the same as that in Example 2, the only difference being that diethanolamine is used instead of polymeric alcohol amine B.

[0052] The accelerators prepared in the above Examples 1-4 and Comparative Examples 1-2 were used in the preparation of concrete, the initial and final setting times of the concrete were recorded, and the concrete strength after curing for 1 day was tested. At the same time, the accelerators were placed in a cool and dark environment, and the morphology of the accelerators after being placed for half a year was observed. The test results are shown in the following table.

[0053] Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Initial setting (min:s) 4:15 3:25 3:12 3:48 4:45 4:30 Final setting (min:s) 10:22 9:46 9:29 9:55 11:30 11:16 1d strength / MPa 9.3 9.2 9.0 8.8 7.8 8.2 Leave for 180 days No stratification No stratification No stratification No stratification Layering Slight delamination

[0054] It can be seen from the above results that, compared with the accelerating setting agent with low molecular alcohol amine, the accelerating setting agent prepared by adding polymeric alcohol amine in Examples 1-4 can further shorten the setting time of concrete and improve the early strength of concrete when applied to concrete. Moreover, after the accelerating setting agent is placed for 6 months, no stratification phenomenon occurs, and the storage time is long.

Claims

1. An alkali-free and fluorine-free liquid accelerating agent, characterized in that: The components and mass ratios of the alkali-free and fluorine-free liquid accelerating setting agent are as follows: The polymerized alcohol amine is obtained by polymerization reaction of acrylate monomer, polyamine monomer and alkylethylene oxide monomer.

2. The alkali-free and fluorine-free liquid quick-setting agent according to claim 1, characterized in that: The preparation method of the polymeric alcohol amine comprises the following steps: (1) Adding acrylate monomer, polyamine monomer and catalyst A into a reaction kettle, heating to 60-130° C., reacting for 2-5 hours, and obtaining an amide compound; wherein the molar ratio of acrylate to polyamine is 1:(1-5), and the mass ratio of catalyst A to the total reactants is 1:(50-100); (2) adding catalyst B and the amide compound obtained in step (1) into a reaction kettle, replacing the atmosphere with nitrogen, heating to 80-120° C., vacuum dehydrating, and then adding an alkylethylene oxide monomer to carry out a polymerization reaction. The polymerization reaction temperature is controlled at 80-120° C., reacting for 10-60 minutes, and cooling to room temperature to obtain an unsaturated alcohol amine; wherein the molar ratio of the amide compound to the alkylethylene oxide monomer is 1:(1-3), and the mass ratio of the catalyst B to the total reactant is 1:(50-100); (3) taking the unsaturated alcohol amine obtained in step (2) and adding it into a reaction kettle, adding a certain amount of an oxidant, and starting to dropwise add a solution consisting of a reducing agent, a chain transfer agent and deionized water for 2 to 4 hours, and keeping the temperature for 1 to 2 hours after the dropwise addition is completed, so as to obtain a polymerized alcohol amine; wherein the molar ratio of the oxidant to the unsaturated alcohol amine is (2 to 5):100, the molar ratio of the reducing agent to the unsaturated alcohol amine is (0.1 to 1):100, and the molar ratio of the chain transfer agent to the unsaturated alcohol amine is (1 to 5):

100.

3. The alkali-free and fluorine-free liquid quick-setting agent according to claim 2, characterized in that: The acrylic acid ester monomer is at least one of methyl acrylate, ethyl acrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.

4. The alkali-free and fluorine-free liquid quick-setting agent according to claim 2, characterized in that: The polyamine monomer is at least one of ethylenediamine, propylenediamine, tetraethylenepentamine and diethylenetriamine.

5. The alkali-free and fluorine-free liquid quick-setting agent according to claim 2, characterized in that: The alkylethylene oxide monomer is at least one of ethylene oxide, propylene oxide and butylene oxide.

6. The alkali-free and fluorine-free liquid quick-setting agent according to claim 2, characterized in that: The catalyst A is at least one of concentrated sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid; the catalyst B is at least one of potassium oxide, sodium hydroxide, potassium hydroxide, potassium hydride, sodium hydride, potassium methoxide, or sodium methoxide.

7. The alkali-free and fluorine-free liquid quick-setting agent according to claim 2, characterized in that: The oxidant is at least one of peracetic acid, hydrogen peroxide, benzoyl peroxide, potassium persulfate, ammonium persulfate, and sodium persulfate; the reducing agent is at least one of bleaching agent, sodium bisulfite, sodium pyrosulfite, ferrous sulfate, ferrous pyrophosphate, sodium hypophosphite, and L-ascorbic acid; the chain transfer agent is at least one of thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptoethanol, mercaptopropanol, sodium methyl acrylate sulfonate, dodecyl mercaptan, undecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, sodium hypophosphite, isopropyl alcohol, trisodium phosphate, sodium formate, and sodium acetate.

8. The alkali-free and fluorine-free liquid quick-setting agent according to claim 1, characterized in that: The soluble aluminum salt is at least one of sodium aluminate, anhydrous aluminum sulfate, polyaluminum sulfate, and aluminum sulfate 18hydrate.

9. The alkali-free and fluorine-free liquid quick-setting agent according to claim 1, characterized in that: The dispersant is any one of hydrated magnesium silicate, polyethylene glycol and polyacrylamide; the pH regulator is at least one of phosphoric acid, ethylenediaminetetraacetic acid, oxalic acid, acetic acid, citric acid and methacrylic acid; and the early strength agent is at least one of lithium carbonate, urea and calcium nitrate.

10. A method for preparing the alkali-free and fluorine-free liquid accelerating setting agent according to claim 1, characterized in that The method comprises the following steps: adding water into a reaction kettle, heating to 60-80°C, sequentially adding a soluble aluminum salt, a dispersant, an early strength agent and a polymeric alcohol amine, keeping the temperature for reaction for 1-2 hours, adding a pH regulator, adjusting the pH to 6-8, and obtaining an alkali-free and fluorine-free liquid accelerating setting agent.

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