Dispersing agent for geopolymer cementing material as well as preparation method and application of dispersing agent

Abstract

The embodiment of the invention discloses a dispersing agent for a geopolymer cementing material as well as a preparation method and application of the dispersing agent. The method comprises the following steps: mixing lignosulfonate, sulfamic acid, heteropoly acid and ethylene glycol, and carrying out degradation and sulfonation reaction to obtain modified lignosulfonate; carrying out esterification reaction on the modified lignosulfonate in the presence of methacrylic acid, a catalyst and a polymerization inhibitor to obtain a modified polymeric monomer; and carrying out polymerization reaction on the modified polymeric monomer and a polyether monomer under the action of an initiator to obtain the polymer. The dispersant disclosed by the invention can play roles in reducing the mixing water consumption and improving the water reducing effect of the dispersant in a geopolymer cementing material system, so that the curing performance defect of a geopolymer cementing material mixture is better solved, application of geopolymers is promoted, meanwhile, a large amount of cement is saved, carbon emission is reduced, and the dispersant has a wide application prospect.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of energy-saving building materials, and in particular to a dispersant for geopolymer gelling materials and a preparation method and application thereof. Background Art

[0002] At present, the preparation of geopolymer cementitious materials is still in the early stage of research and development, and has not been widely used in related engineering fields. A large amount of alkaline materials need to be added during the preparation of this system material, which makes it impossible for the traditional silicate-based concrete water-reducing dispersant to fully play its role in geopolymer cementitious materials. This makes it difficult to reduce the amount of water used in the geopolymer cementitious material mixture during mixing, which in turn causes a series of problems, such as low strength after curing, obvious shrinkage and other durability problems, which seriously limits the widespread application of geopolymer cementitious materials. Summary of the invention

[0003] To this end, the embodiments of the present invention provide a dispersant for geopolymer cementitious materials and a preparation method and application thereof. The dispersant can reduce the amount of mixing water in the geopolymer cementitious material system and improve the water-reducing effect of the dispersant, thereby better solving the curing performance defects of the geopolymer cementitious material mixture, promoting the application of geopolymers while achieving a large amount of cement savings and reducing carbon emissions, and has broad application prospects.

[0004] In order to achieve the above purpose, the embodiment of the present invention provides the following technical solutions:

[0005] According to a first aspect of an embodiment of the present invention, the present invention provides a method for preparing a dispersant for a geopolymer gelling material, the method comprising:

[0006] The lignin sulfonate, aminosulfonic acid, heteropoly acid and ethylene glycol are mixed and subjected to degradation and sulfonation reaction to obtain modified lignin sulfonate;

[0007] The modified lignin sulfonate is subjected to an esterification reaction in the presence of methacrylic acid, a catalyst and a polymerization inhibitor to obtain a modified polymerization monomer;

[0008] The modified polymer monomer and the polyether monomer undergo a polymerization reaction under the action of an initiator to obtain a polymer.

[0009] Further, the mass ratio of the lignin sulfonate, aminosulfonic acid, heteropoly acid and ethylene glycol is 40-50:15-25:5-6:300;

[0010] The temperature of the degradation and sulfonation reaction is 80-95°C and the time is 1.5-2.5h;

[0011] The heteropoly acid includes phosphotungstic acid, silicotungstic acid, and carbon-based solid acid.

[0012] Furthermore, the mass ratio of the modified lignin sulfonate, methacrylic acid, catalyst, and inhibitor is 350-400: 600-650: 7-10: 0.5-1.0;

[0013] The catalyst includes p-toluenesulfonic acid;

[0014] The polymerization inhibitor includes methyl hydroquinone, hydroquinone, p-methoxyphenol, and phenothiazine;

[0015] The temperature of the esterification reaction is 90-100° C. and the time is 2.5-3.0 hours.

[0016] Furthermore, the polyether monomer includes allyl polyoxyethylene ether and methyl allyl polyoxyethylene ether;

[0017] The initiator includes hydrogen peroxide, ammonium persulfate and sodium percarbonate.

[0018] Further, 50-70g of modified polymer monomer, 50-70g of deionized water, and 10-15g of acrylic acid are mixed to form liquid A; 1-2g of mercaptoethanol, 0.5-1g of vitamin C, and 50-70g of deionized water are mixed to form liquid B; 4-6g of hydrogen peroxide and 15-25g of deionized water are mixed to form liquid C;

[0019] 300-350g of deionized water and 300-350g of polyether monomer are added to a reaction container and stirred to dissolve, and then 1.0-2.0g of 0.5-2% ferrous sulfate solution is added, and liquid C is first added dropwise to the reaction container, and then liquid A and liquid B are added dropwise after 8-12 minutes, and liquid A is added within 110-130 minutes, liquid B is added within 130-150 minutes, and liquid C is added within 140-160 minutes, and alkali is added for neutralization, and drying and dehydration are performed to obtain the polymer.

[0020] Furthermore, the method further comprises: mixing the polymer with modified microsilica fume, wherein the mass proportion of the modified microsilica fume is 70-80%;

[0021] The preparation method of the modified microsilica powder comprises:

[0022] The microsilica powder is dispersed by air jet mill, and 0.1-0.6% of fluorosilane by mass of the microsilica powder is added and mixed to obtain the modified microsilica powder.

[0023] Furthermore, the fluorosilane includes trifluoropropyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane.

[0024] According to a second aspect of an embodiment of the present invention, the present invention provides a dispersant for geopolymer gelling material, which is prepared by any preparation method as described above.

[0025] According to a third aspect of an embodiment of the present invention, the present invention provides use of the above-mentioned dispersant for geopolymer gelling material in the preparation of geopolymer gelling material.

[0026] The embodiments of the present invention have the following advantages:

[0027] Compared with the prior art, the present invention improves the molecular structure of the existing polymer dispersant and introduces functional groups such as macromolecular sulfonic acid groups, benzene sulfonic groups, and phenol groups. The polymer molecular structure has a significant change compared to the comb-shaped structure of conventional dispersants, which significantly improves the dispersibility of the dispersant in the geopolymer cementitious material mixture system. At the same time, combined with the ball effect after the hydrophobic microsilica powder is modified, the dual effects are superimposed, effectively reducing the amount of mixing water, improving the various properties of the geopolymer after curing, overcoming the defects of the existing geopolymer cementitious materials, and providing the possibility for large-scale application of geopolymer cementitious materials. DETAILED DESCRIPTION

[0028] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Sodium lignin sulfonate: molecular weight 1000-5000, from Shixian Shuanglu Company;

[0030] Polyether monomers: allyl polyoxyethylene ether (HPEG) and methyl allyl polyoxyethylene ether (TPEG), both from Satellite Chemical.

[0031] Example 1

[0032] This embodiment provides a dispersant for geopolymer gelling material, and the preparation method thereof comprises the following steps:

[0033] (1) Take 46 g of sodium lignin sulfonate, 16 g of aminosulfonic acid, 5 g of phosphotungstic acid, and 300 g of ethylene glycol and add them into a microwave reactor, connect a condenser, control the temperature to 85° C., and react for 2 h to obtain modified sodium lignin sulfonate.

[0034] (2) Take 350 g of modified sodium lignin sulfonate, 620 g of methacrylic acid, 8 g of p-toluenesulfonic acid, and 1.0 g of methylhydroquinone and add them into a microwave reactor. Install a condenser, control the temperature to 95° C., and react for 2.5 h to obtain a modified polymer monomer.

[0035] (3) 60 g of the modified polymer monomer, 60 g of deionized water, and 12 g of acrylic acid were mixed to obtain liquid A; 1.5 g of mercaptoethanol, 0.8 g of vitamin C, and 60 g of deionized water were mixed to obtain liquid B; 5.0 g of hydrogen peroxide was mixed with 20 g of deionized water to obtain liquid C.

[0036] Add 320g of deionized water, 350g of allyl polyoxyethylene ether, and 1.5g of 1% ferrous sulfate aqueous solution to the reaction container. Then, add the mixed liquid C to the reaction container. After 10 minutes of liquid C, liquid A and liquid B are added simultaneously. Add liquid A in 120 minutes, liquid B in 140 minutes, and liquid C in 150 minutes. Add sodium hydroxide to neutralize, dry and dehydrate the obtained reactants, and the obtained powdered polymer is the dispersant for geopolymer gelling materials.

[0037] Example 2

[0038] This embodiment provides a dispersant for geopolymer gelling material, and the preparation method thereof includes:

[0039] (1) Take 50 g of sodium lignin sulfonate, 20 g of aminosulfonic acid, 6 g of silicotungstic acid, and 300 g of ethylene glycol and add them into a microwave reactor, connect a condenser, control the temperature to 88° C., and react for 2 h to obtain modified sodium lignin sulfonate.

[0040] (2) Take 400 g of modified sodium lignin sulfonate, 650 g of methacrylic acid, 8 g of p-toluenesulfonic acid, and 1.0 g of hydroquinone and add them into a microwave reactor for reaction. Install a condenser, control the temperature to 90° C., and react for 2.5 h to obtain a modified polymer monomer.

[0041] (3) 60 g of modified polymer monomer, 60 g of deionized water, and 12 g of acrylic acid were mixed to obtain liquid A; 1.8 g of mercaptoethanol, 0.5 g of vitamin C, and 50 g of deionized water were mixed to obtain liquid B; 4.2 g of hydrogen peroxide was mixed with 22 g of deionized water to obtain liquid C.

[0042] Add 350g of deionized water, 350g of methyl allyl polyoxyethylene ether, and 1.5g of 1% ferrous sulfate aqueous solution to the reaction container. Then, add the mixed liquid C to the reaction container. After 10 minutes of adding liquid C, liquid A and liquid B are added simultaneously. Add liquid A in 130 minutes, liquid B in 150 minutes, and liquid C in 140 minutes. Add sodium hydroxide to neutralize, dry and dehydrate the obtained reactants, and the obtained powdered polymer is the dispersant for geopolymer gelling materials.

[0043] Example 3

[0044] This embodiment provides a dispersant for geopolymer gelling material, and the preparation method thereof includes:

[0045] (1) Take 40 g of sodium lignin sulfonate, 25 g of aminosulfonic acid, 6 g of carbon-based solid acid, and 300 g of ethylene glycol and add them into a microwave reactor, connect a condenser, control the temperature to 85° C., and react for 2 h to obtain modified sodium lignin sulfonate.

[0046] (2) Take 400 g of modified sodium lignin sulfonate, 600 g of methacrylic acid, 7 g of p-toluenesulfonic acid, and 1.0 g of phenothiazine, add them into a microwave reactor, install a condenser, control the temperature to 98° C., and react for 2.5 h to obtain a modified polymer monomer.

[0047] (3) 65 g of the modified polymer monomer, 70 g of deionized water, and 10 g of acrylic acid were mixed to obtain liquid A; 2 g of mercaptoethanol, 0.5 g of vitamin C, and 65 g of deionized water were mixed to obtain liquid B; 6 g of hydrogen peroxide was mixed with 25 g of deionized water to obtain liquid C.

[0048] Add 350g of deionized water, 360g of allyl polyoxyethylene ether, and 1.8g of 1% ferrous sulfate aqueous solution to the reaction container. Then, add the mixed liquid C to the reaction container. After 10 minutes of liquid C, liquid A and liquid B are added simultaneously. Add liquid A in 120 minutes, liquid B in 140 minutes, and liquid C in 150 minutes. Add sodium hydroxide to neutralize, dry and dehydrate the obtained reactants, and the obtained powdered polymer is the dispersant for geopolymer gelling materials.

[0049] Example 4

[0050] This embodiment provides a dispersant for geopolymer gelling material, and the preparation method thereof includes:

[0051] (1) Preparation of modified microsilica powder: The microsilica powder was dispersed by air jet mill, and trifluoropropyltrimethoxysilane was added at a mass ratio of 0.3% of the microsilica powder and mixed.

[0052] (2) The polymer prepared in Example 1 was mixed with modified microsilica powder in a mass ratio of 3:7.

[0053] Example 5

[0054] This embodiment provides a dispersant for geopolymer gelling material, and the preparation method thereof includes:

[0055] (1) Preparation of modified microsilica powder: The microsilica powder was dispersed by air jet mill, and 0.6% of heptadecafluorodecyltrimethoxysilane by mass ratio of the microsilica powder was added and mixed.

[0056] (2) The polymer prepared in Example 2 was mixed with modified microsilica powder in a mass ratio of 3:7.

[0057] Test Example 1

[0058] Mortar test:

[0059] According to the ratio of cementitious material to sand of 1:3 and the water-cement ratio of 0.6, 450g of geopolymer cementitious material, 1350g of sand, and 22.5g of water glass with a modulus of 1.0 were taken, and 0.3% of conventional powder (carboxylic acid) water reducer on the market and 0.3% and 0.9% of the dispersant obtained by the present invention were added respectively. The mortar rheology was compared after stirring with a mortar mixer. The test results are shown in Table 1 below.

[0060] Table 1

[0061]

[0062] The test results show that the mortar expansion of the conventional water-reducing dispersant is 130mm×130mm, and the mortar flow static time is 3.0 seconds; the mortar expansion of the dispersant obtained by the present method is 180mm×180mm, and the mortar flow static time is greater than 3.9 seconds. This shows that the charge repulsion effect of the dispersant obtained by the present method is greater than that of the conventional dispersant. When the conventional water-reducing dispersant increases the mixing water amount and the water-cement ratio is adjusted to 0.635, the mortar expansion is 175mm×178mm, and the mortar flow static time is 3.9 seconds. It can be seen that the conventional dispersant has weak dispersibility in the strong alkaline geopolymer cementitious material. If the mortar dispersibility of the dispersant obtained by the present invention is to be achieved, the mortar mixing water amount needs to be increased, which will lead to reduced strength and increased crack risk. At the same time, it can be seen from the strength of the mortar 7 and 28 days after hardening that although the fluidity of the conventional dispersant mixed mortar increases from 130mm to 175mm, the strength has also decreased by at least 10%.

[0063] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A method for preparing a dispersant for geopolymer gelling material, characterized in that: The method comprises: The lignin sulfonate, aminosulfonic acid, heteropoly acid and ethylene glycol are mixed and subjected to degradation and sulfonation reaction to obtain modified lignin sulfonate; The modified lignin sulfonate is subjected to an esterification reaction in the presence of methacrylic acid, a catalyst and a polymerization inhibitor to obtain a modified polymerization monomer; The modified polymer monomer and the polyether monomer undergo a polymerization reaction under the action of an initiator to obtain a polymer.

2. The method for preparing a dispersant for geopolymer gelling material according to claim 1, characterized in that: The mass ratio of the lignin sulfonate, aminosulfonic acid, heteropoly acid and ethylene glycol is 40-50:15-25:5-6:300; The temperature of the degradation and sulfonation reaction is 80-95°C and the time is 1.5-2.5h; The heteropoly acid includes phosphotungstic acid, silicotungstic acid, and carbon-based solid acid.

3. The method for preparing a dispersant for geopolymer gelling material according to claim 1, characterized in that: The mass ratio of the modified lignin sulfonate, methacrylic acid, catalyst and inhibitor is 350-400: 600-650: 7-10: 0.5-1.0; The catalyst includes p-toluenesulfonic acid; The polymerization inhibitor includes methyl hydroquinone, hydroquinone, p-methoxyphenol, and phenothiazine; The temperature of the esterification reaction is 90-100° C. and the time is 2.5-3.0 hours.

4. The method for preparing a dispersant for geopolymer gelling material according to claim 1, characterized in that: The polyether monomers include allyl polyoxyethylene ether and methyl allyl polyoxyethylene ether; The initiator includes hydrogen peroxide, ammonium persulfate and sodium percarbonate.

5. The method for preparing a dispersant for geopolymer gelling material according to claim 1, characterized in that: Mix 50-70g of modified polymer monomer, 50-70g of deionized water, and 10-15g of acrylic acid as liquid A; mix 1-2g of mercaptoethanol, 0.5-1g of vitamin C, and 50-70g of deionized water as liquid B; mix 4-6g of hydrogen peroxide with 15-25g of deionized water as liquid C; 300-350g of deionized water and 300-350g of polyether monomer are added to a reaction container and stirred to dissolve, and then 1.0-2.0g of 0.5-2% ferrous sulfate solution is added, and liquid C is first added dropwise to the reaction container, and then liquid A and liquid B are added dropwise after 8-12 minutes, and liquid A is added within 110-130 minutes, liquid B is added within 130-150 minutes, and liquid C is added within 140-160 minutes, and alkali is added for neutralization, and drying and dehydration are performed to obtain the polymer.

6. The method for preparing a dispersant for geopolymer gelling material according to claim 1, characterized in that: The method further comprises: mixing the polymer with modified microsilica fume, wherein the mass proportion of the modified microsilica fume is 70-80%; The preparation method of the modified microsilica powder comprises: The microsilica powder is dispersed by air jet mill, and 0.1-0.6% of fluorosilane by mass of the microsilica powder is added and mixed to obtain the modified microsilica powder.

7. The method for preparing a dispersant for geopolymer gelling material according to claim 6, characterized in that: The fluorosilane includes trifluoropropyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane.

8. A dispersant for geopolymer gelling material, characterized in that: The invention is prepared by the preparation method described in any one of claims 1 to 7.

9. Use of the dispersant for geopolymer gelling material according to claim 8 in the preparation of geopolymer gelling material.

Images