Cement-based grouting material containing modified polycarboxylate superplasticizer and preparation process

Abstract

The cement-based grouting material is prepared from the following raw materials in parts by weight: 350 to 450 parts of cement, 50 to 100 parts of coal ash, 520 to 650 parts of sand, 220 to 300 parts of water, 4 to 12 parts of hyperbranched modified polycarboxylic acid water reducing agent and 60 to 110 parts of steel fiber. The hyperbranched modified polycarboxylic acid water reducing agent contains a four-arm star-shaped polycarboxylic acid polyether branched molecular chain, larger steric hindrance can be formed, mutual aggregation of cement particles is inhibited, the dispersing performance of cement silicate particles is improved, the molecular chain of the hyperbranched modified polycarboxylic acid water reducing agent contains a quaternary ammonium salt structure, an anti-polyelectrolyte effect is formed, and the cement silicate particles can be dispersed in the hyperbranched modified polycarboxylic acid water reducing agent. The molecular chain of the water reducing agent is expanded to form a more stretched adsorption form, so that the dispersing performance of cement silicate particles is further improved, and the compressive strength of cement is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of cement, in particular to a cement-based grouting material containing a modified polycarboxylic acid water-reducing agent and a preparation process thereof. Background Art

[0002] Cement-based grouting materials are mainly composed of cement, sand, fiber reinforcement, water reducer, etc., among which water reducer can improve the dispersibility of cement, improve fluidity, save cement dosage, enhance cement concrete strength, reduce slump loss, etc. At present, water reducers mainly include polycarboxylate water reducer, naphthalene water reducer, and sulfonic acid water reducer; among which most polycarboxylate water reducers are linear comb-shaped structures, with poor steric hindrance effect and poor dispersibility of cement. Hyperbranched water reducer, star-shaped multi-arm water reducer, etc. contain multiple polymer molecular chains, which can play a better steric hindrance effect and dispersibility. Patent CN115819683A discloses a solid four-arm star-shaped polycarboxylate water reducer and its preparation method, using a compound containing dithioester at the end of the four arms as a chain transfer agent, and adopting a reversible addition-fragmentation chain transfer polymerization method, the obtained polycarboxylate water reducer contains a polycarboxylate water reducer molecular chain with a comb-shaped structure, which can effectively improve the steric hindrance and dispersibility of the polycarboxylate water reducer in cement particles, and has good slump retention performance. However, the preparation method of the four-arm star-shaped dithioester chain transfer agent is relatively complicated, and compared with a single polycarboxylic acid water reducer, the introduction of cationic groups and the like into the water reducer molecular chain can further improve the dispersibility of the water reducer. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In view of the deficiencies of the prior art, the present invention provides a cement-based grouting material containing a modified polycarboxylic acid water-reducing agent with high strength and better dispersibility.

[0005] (II) Technical solution

[0006] A cement-based grouting material containing a modified polycarboxylate water reducer comprises the following raw materials in parts by weight: 350-450 parts of cement, 50-100 parts of fly ash, 520-650 parts of sand, 220-300 parts of water, 4-12 parts of hyperbranched modified polycarboxylate water reducer, and 60-110 parts of steel fiber.

[0007] The preparation process of the hyperbranched modified polycarboxylic acid water reducer is as follows: pentaerythritol tetra(thiobromoethyl propionate) acetate, acrylic acid, acrylate cationic polyethylene glycol monomethyl ether, and 2,2'-bipyridine are added to an ethanol aqueous solution, mixed well, and then sodium hydroxide is added, and the mixture is frozen in liquid nitrogen, vacuumized, and thawed, and then cuprous bromide is added, and the mixture is reacted in a nitrogen atmosphere, and after the reaction, acetone is added to precipitate the precipitate, which is filtered, washed with acetone, and dried to obtain a hyperbranched modified polycarboxylic acid water reducer. The reaction mechanism is as follows:

[0008]

[0009] The molar ratio of pentaerythritol tetrakis(thiobromoethylpropionate) acetate, acrylic acid, and acrylate cationic polyethylene glycol monomethyl ether is 1:(30-70):(12-28).

[0010] The volume fraction of the ethanol aqueous solution is 60-80%.

[0011] Wherein, sodium hydroxide is added to adjust the solution pH to 8-9.

[0012] The reaction temperature is 75-90°C and the reaction time is 24-36h.

[0013] The preparation method of pentaerythritol tetrakis (thiobromoethyl propionate) acetate is as follows: pentaerythritol tetrakis (CAS No. 10193-99-4), 2-bromoethyl acrylate (CAS No. 4823-47-6), and benzoin dimethyl ether are added to tetrahydrofuran in a molar ratio of 1: (4-4.8): (0.04-0.05), and the mixture is irradiated under a 200-500W ultraviolet lamp for 30-60 minutes to react, and the solution is concentrated, washed with n-hexane, and dried to obtain pentaerythritol tetrakis (thiobromoethyl propionate) acetate. The reaction formula is:

[0014]

[0015] Wherein, the preparation method of acrylate cationic polyethylene glycol monomethyl ether is:

[0016] (1) Add polyethylene glycol monomethyl ether, N,N-dimethylglycine (CAS No. 1118-68-9), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 4-dimethylaminopyridine in a molar ratio of 1:(2.5-3.2):(2.5-3.2):(0.2-0.26) to N,N-dimethylformamide, react at room temperature for 12-18 hours, remove N,N-dimethylformamide by vacuum distillation, wash with n-hexane, and dry to obtain tertiary amino polyethylene glycol monomethyl ether. The reaction formula is:

[0017]

[0018] (2) Add tertiary amino polyethylene glycol monomethyl ether and 2-bromoethyl acrylate in a molar ratio of 1:(4.5-6.8) to N,N-dimethylformamide, react at 100-130°C for 24-48h, remove N,N-dimethylformamide by vacuum distillation, wash with n-hexane, and dry to obtain acrylate cationic polyethylene glycol monomethyl ether. The reaction formula is:

[0019] Among them, the preparation process of cement-based grouting material containing modified polycarboxylic acid water reducer is as follows: cement, fly ash, sand, water, hyperbranched modified polycarboxylic acid water reducer and steel fiber are added into a mixing barrel, and stirred for 6-10 minutes to obtain cement-based grouting material containing modified polycarboxylic acid water reducer.

[0020] (III) Technical effect: The present invention utilizes pentaerythritol tetrathioglycolate and 2-bromoethyl acrylate to carry out mercapto-ene photo-click reaction to obtain novel pentaerythritol tetrakis (thiobromoethyl propionate) acetate.

[0021] The invention uses polyethylene glycol monomethyl ether and N,N-dimethylglycine to carry out esterification reaction to obtain tertiary amine polyethylene glycol monomethyl ether, and then carries out quaternization reaction with 2-bromoethyl acrylate to obtain acrylate cationic polyethylene glycol monomethyl ether containing alkenyl and cationic groups.

[0022] The invention uses pentaerythritol tetra(thiobromoethyl propionate) acetate as an initiator, which contains four bromoethyl initiation polymerization sites, and initiates acrylic acid and acrylate cationic polyethylene glycol monomethyl ether to carry out ATRP polymerization reaction in a catalytic system of 2,2'-bipyridine and cuprous bromide, thereby obtaining a hyperbranched modified polycarboxylic acid water reducer containing a four-arm star-shaped branched molecular chain.

[0023] The present invention uses silicate cement, fly ash, sand and steel fiber as the main components of cement grouting material, and adds novel hyperbranched modified polycarboxylate water reducer at the same time, the water reducer contains a four-arm star-shaped comb-type polycarboxylate polyether branched molecular chain, can promote the water reducer to contact with the cement silicate surface, enhance the adsorption performance of the water reducer and the cement silicate surface, form a larger steric hindrance, and the hydration film generated by the water reducer on the silicate surface at the same time can make cement particles moist, easy to slide, thereby inhibiting cement particles from mutually aggregating, significantly improving the dispersibility of cement silicate particles, and making the dispersion system of cement grouting material tend to be stable. At the same time, the molecular chain of the hyperbranched modified polycarboxylate water reducer contains a quaternary ammonium salt structure, forms an anti-polyelectrolyte effect, is the molecular chain of the water reducer expands, forms a more stretched adsorption form, further improves the dispersibility of cement silicate particles, and enhances the compressive strength of cement. DETAILED DESCRIPTION

[0024] The cement is PO42.5 silicate; the average particle size of fly ash is 200 mesh; the particle size of sand is 40-80 mesh; the specification of steel fiber is 35mm×0.75mm.

[0025] Example 1

[0026] (1) To 15 mL of tetrahydrofuran, 2 mmol of pentaerythritol tetrathioglycolate, 8 mmol of 2-bromoethyl acrylate and 0.1 mmol of benzoin dimethyl ether were added, and the mixture was reacted for 30 min under a nitrogen atmosphere and a 500 W ultraviolet lamp. The solution was concentrated, washed with n-hexane and dried to obtain pentaerythritol tetrakis(thiobromoethylpropionate) acetate.

[0027] Example 2

[0028] (1) To 20 mL of tetrahydrofuran, 2 mmol of pentaerythritol tetrathioglycolate, 9.6 mmol of 2-bromoethyl acrylate and 0.08 mmol of benzoin dimethyl ether were added, and the mixture was reacted for 60 min under a nitrogen atmosphere and a 200 W ultraviolet lamp. The solution was concentrated, washed with n-hexane and dried to obtain pentaerythritol tetrakis(thiobromoethylpropionate) acetate.

[0029] Example 3

[0030] (1) To 200 mL of N,N-dimethylformamide, 30 mmol of polyethylene glycol monomethyl ether 1000, 75 mmol of N,N-dimethylglycine, 75 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 7.8 mmol of 4-dimethylaminopyridine were added, and the mixture was reacted at room temperature for 12 h. N,N-dimethylformamide was removed by distillation under reduced pressure, and the mixture was washed with n-hexane and dried to obtain tertiary amino polyethylene glycol monomethyl ether.

[0031] (2) Add 30 mmol of tertiary amino polyethylene glycol monomethyl ether and 204 mmol of 2-bromoethyl acrylate to 400 mL of N,N-dimethylformamide, react at 100° C. for 48 h, remove N,N-dimethylformamide by distillation under reduced pressure, wash with n-hexane, and dry to obtain acrylate cationic polyethylene glycol monomethyl ether.

[0032] Example 4

[0033] (1) To 300 mL of N,N-dimethylformamide, 30 mmol of polyethylene glycol monomethyl ether 1000, 96 mmol of N,N-dimethylglycine, 96 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 6 mmol of 4-dimethylaminopyridine were added, and the mixture was reacted at room temperature for 18 h. N,N-dimethylformamide was removed by distillation under reduced pressure, and the mixture was washed with n-hexane and dried to obtain tertiary amino polyethylene glycol monomethyl ether.

[0034] (2) Add 30 mmol of tertiary amino polyethylene glycol monomethyl ether and 135 mmol of 2-bromoethyl acrylate to 300 mL of N,N-dimethylformamide, react at 130° C. for 24 h, remove N,N-dimethylformamide by distillation under reduced pressure, wash with n-hexane, and dry to obtain acrylate cationic polyethylene glycol monomethyl ether.

[0035] Example 5

[0036] (1) 1 mmol of pentaerythritol tetra(thiobromoethyl propionate) acetate (prepared according to the method of Example 1), 30 mmol of acrylic acid, 12 mmol of acrylate cationic polyethylene glycol monomethyl ether (prepared according to the method of Example 3), and 6 mmol of 2,2'-bipyridine were added to 20 mL of 80% ethanol aqueous solution, mixed, and then sodium hydroxide was added to adjust the pH of the solution to 8, and the solution was frozen in liquid nitrogen, vacuumized, and thawed. Then, 11 mmol of cuprous bromide was added, and the reaction was carried out at 80° C. in a nitrogen range for 24 hours. After the reaction, acetone was added to precipitate, and the precipitate was filtered, washed with acetone, and dried to obtain a hyperbranched modified polycarboxylic acid water reducer.

[0037] (2) Add 380 g of cement, 60 g of fly ash, 620 g of sand, 270 g of water, 4 g of hyperbranched modified polycarboxylate water reducer, and 60 g of steel fiber into a mixing bucket; stir for 6 minutes to obtain a cement-based grouting material containing a modified polycarboxylate water reducer.

[0038] Example 6

[0039] (1) 1 mmol of pentaerythritol tetra(thiobromoethylpropionate) acetate (prepared according to the method of Example 1), 40 mmol of acrylic acid, 16 mmol of acrylate cationic polyethylene glycol monomethyl ether (prepared according to the method of Example 3), and 6.6 mmol of 2,2'-bipyridine were added to 30 mL of 80% ethanol aqueous solution, mixed, and then sodium hydroxide was added to adjust the pH of the solution to 8, and the solution was frozen in liquid nitrogen, vacuumized, and thawed, and then 12 mmol of cuprous bromide was added, and the reaction was carried out at 90° C. in a nitrogen range for 24 hours. After the reaction, acetone was added to precipitate, and the precipitate was filtered, washed with acetone, and dried to obtain a hyperbranched modified polycarboxylic acid water reducer.

[0040] (2) Add 350 g of cement, 100 g of fly ash, 520 g of sand, 280 g of water, 7 g of hyperbranched modified polycarboxylate water reducer, and 80 g of steel fiber into a mixing bucket; stir for 10 min to obtain a cement-based grouting material containing a modified polycarboxylate water reducer.

[0041] Example 7

[0042] (1) 1 mmol of pentaerythritol tetra(thiobromoethylpropionate) acetate (prepared according to the method of Example 1), 55 mmol of acrylic acid, 22 mmol of acrylate cationic polyethylene glycol monomethyl ether (prepared according to the method of Example 3), and 7.4 mmol of 2,2'-bipyridine were added to 50 mL of 60% ethanol aqueous solution, mixed, and then sodium hydroxide was added to adjust the pH of the solution to 9, and the solution was frozen in liquid nitrogen, vacuumized, and thawed. Then, 15 mmol of cuprous bromide was added, and the reaction was carried out at 75° C. in a nitrogen range for 36 hours. After the reaction, acetone was added to precipitate, and the precipitate was filtered, washed with acetone, and dried to obtain a hyperbranched modified polycarboxylic acid water reducer.

[0043] (2) Add 350 g of cement, 100 g of fly ash, 650 g of sand, 300 g of water, 10 g of hyperbranched modified polycarboxylate water reducer, and 90 g of steel fiber into a mixing bucket; stir for 10 min to obtain a cement-based grouting material containing a modified polycarboxylate water reducer.

[0044] Example 8

[0045] (1) 1 mmol of pentaerythritol tetra(thiobromoethylpropionate) acetate (prepared according to the method of Example 1), 70 mmol of acrylic acid, 28 mmol of acrylate cationic polyethylene glycol monomethyl ether (prepared according to the method of Example 3), and 8 mmol of 2,2'-bipyridine were added to 50 mL of 60% ethanol aqueous solution, mixed and then sodium hydroxide was added to adjust the pH of the solution to 9, and the solution was frozen in liquid nitrogen, vacuumized, and thawed, and then 16 mmol of cuprous bromide was added, and the reaction was carried out at 90° C. in a nitrogen range for 30 hours. After the reaction, acetone was added to precipitate, and the precipitate was filtered, washed with acetone, and dried to obtain a hyperbranched modified polycarboxylic acid water reducer.

[0046] (2) Add 450 g of cement, 50 g of fly ash, 520 g of sand, 220 g of water, 12 g of hyperbranched modified polycarboxylate water reducer, and 110 g of steel fiber into a mixing bucket; stir for 60 min to obtain a cement-based grouting material containing a modified polycarboxylate water reducer.

[0047] Comparative Example 1

[0048] Add 380 g of cement, 60 g of fly ash, 620 g of sand, 270 g of water, and 60 g of steel fiber into a mixing bucket; stir for 6 minutes to obtain a cement-based grouting material.

[0049] Comparative Example 2

[0050] (1) 1 mmol of pentaerythritol tetra(thiobromoethylpropionate) acetate (prepared according to the method of Example 1), 30 mmol of acrylic acid, and 6 mmol of 2,2'-bipyridine were added to 20 mL of 80% ethanol aqueous solution, mixed, and then sodium hydroxide was added to adjust the pH of the solution to 8, and the solution was frozen in liquid nitrogen, vacuumized, and thawed. Then, 11 mmol of cuprous bromide was added, and the reaction was carried out at 80° C. in a nitrogen range for 24 hours. After the reaction, acetone was added to precipitate, and the precipitate was filtered, washed with acetone, and dried to obtain a hyperbranched modified polycarboxylic acid water reducer.

[0051] (2) Add 380 g of cement, 60 g of fly ash, 620 g of sand, 270 g of water, 4 g of hyperbranched modified polycarboxylate water reducer, and 60 g of steel fiber into a mixing bucket; stir for 6 minutes to obtain a cement-based grouting material containing a modified polycarboxylate water reducer.

[0052] Comparative Example 3

[0053] (1) 1 mmol of pentaerythritol tetra(thiobromoethyl propionate) acetate (prepared according to the method of Example 1), 30 mmol of acrylic acid, 12 mmol of allyl polyoxyethylene ether (APEG1000, structural formula: ), 6 mmol 2,2'-bipyridine is added to 20 mL of 80% ethanol aqueous solution by volume, and after mixing, sodium hydroxide is added to adjust the pH value of the solution to 8, and the solution is frozen in liquid nitrogen, vacuumized, and thawed. Then, 11 mmol cuprous bromide is added, and the reaction is carried out at 80°C in a nitrogen atmosphere for 24 hours. After the reaction, acetone is added to precipitate, and the precipitate is filtered, washed with acetone, and dried to obtain a hyperbranched modified polycarboxylic acid water reducer.

[0054] (2) Add 380 g of cement, 60 g of fly ash, 620 g of sand, 270 g of water, 4 g of hyperbranched modified polycarboxylate water reducer, and 60 g of steel fiber into a mixing bucket; stir for 6 minutes to obtain a cement-based grouting material containing a modified polycarboxylate water reducer.

[0055] Comparative Example 4

[0056] (1) 1 mmol of ethyl 2-bromopropionate (structural formula: ), 30 mmol acrylic acid, 12 mmol acrylate cationic polyethylene glycol monomethyl ether (prepared according to the method of Example 3), and 6 mmol 2,2'-bipyridine are added to 20 mL of 80% ethanol aqueous solution by volume, mixed, and then sodium hydroxide is added to adjust the pH of the solution to 8, and the solution is frozen in liquid nitrogen, vacuumized, and thawed. Then, 11 mmol cuprous bromide is added, and the reaction is carried out at 80° C. in a nitrogen range for 24 hours. After the reaction, acetone is added to precipitate, and the precipitate is filtered, washed with acetone, and dried to obtain a polycarboxylate water reducer.

[0057] (2) Add 380 g of cement, 60 g of fly ash, 620 g of sand, 270 g of water, 4 g of polycarboxylate water reducer, and 60 g of steel fiber into a mixing bucket; stir for 6 minutes to obtain a cement-based grouting material containing polycarboxylate water reducer.

[0058] Comparative Example 5

[0059] (1) Add 380 g of cement, 60 g of fly ash, 620 g of sand, 270 g of water, 4 g of CP1801X polycarboxylate water reducer, and 60 g of steel fiber into a mixing bucket; stir for 6 minutes to obtain a cement-based grouting material containing a polycarboxylate water reducer.

[0060] According to the GB / T8077-2012 method, the fluidity of cement-based grouting material is tested. The greater the fluidity of the cement-based grout, the better the dispersibility.

[0061] Table 1 Test of fluidity of pure slurry

[0062]

[0063]

[0064] Pour the cement-based grouting material containing modified polycarboxylate water-reducing agent into the mold, vibrate to degas, solidify and shape, and cure at room temperature for 7-28 days. Test the compressive strength of cement according to GB / T 17671-2021 method.

[0065] Table 2 Cement compressive strength test

[0066]

[0067] It can be seen from Table 1 and Table 2 that the initial clean paste fluidity of embodiment 5-8 reaches 295-335mm, and the 1h clean paste fluidity still remains at 293-327mm; The larger the clean paste fluidity, the better the dispersibility of cement grouting material. This is because the added hyperbranched modified polycarboxylate water-reducing agent contains a four-arm star-shaped comb-type polycarboxylate polyether branched molecular chain, which can promote the contact between the water-reducing agent and the cement silicate surface, enhance the adsorption performance of the water-reducing agent and the cement silicate surface, form a larger steric hindrance, and the hydration film generated by the water-reducing agent on the silicate surface can make the cement particles wet, easy to slide, thereby inhibiting the mutual aggregation of cement particles, significantly improving the dispersibility of cement silicate particles, and making the dispersion system of cement grouting material tend to be stable. At the same time, the molecular chain of the hyperbranched modified polycarboxylate water-reducing agent contains a quaternary ammonium salt structure, forming an anti-polyelectrolyte effect, which is the molecular chain of the water-reducing agent. It forms a more stretched adsorption form, further improves the dispersibility of cement silicate particles, and enhances the compressive strength of cement. The compressive strength of cement after curing for 28 days reaches 77.1-109.8MPa.

[0068] In Comparative Example 1, no hyperbranched modified polycarboxylate water-reducing agent was added, the dispersibility of cement particles was very poor, the fluidity of the slurry was very low, and the compressive strength was poor.

[0069] Compared with Example 5, in Comparative Example 2, a hyperbranched modified polycarboxylate water-reducing agent is prepared, and no acrylate cationic polyethylene glycol monomethyl ether is added. The water-reducing agent does not contain a comb-type polyether long chain and a cationic group, and it is difficult to form a larger steric hindrance on the silicate surface, and it is also impossible to produce an anti-polyelectrolyte effect. The dispersibility of cement particles is poor, the fluidity of the net slurry is low, and the compressive strength of the cement is poor.

[0070] Comparative Example 3 uses conventional allyl polyoxyethylene ether instead of acrylate cationic polyethylene glycol monomethyl ether. The obtained hyperbranched modified polycarboxylate water reducer does not contain cationic groups and cannot produce anti-polyelectrolyte effect. The dispersibility of cement particles is poor, the fluidity of the net slurry is low, and the compressive strength of the cement is poor.

[0071] In Comparative Example 4, ethyl 2-bromopropionate is used as an initiator, and the obtained water reducer does not contain a four-arm star-shaped polycarboxylic acid polyether branched molecular chain, cannot promote the contact between the water reducer and the cement silicate surface, cannot enhance the adsorption performance of the water reducer and the cement silicate surface, is difficult to achieve greater steric hindrance, has poor dispersibility of cement particles, has low net slurry fluidity, and has poor compressive strength of cement.

[0072] Comparative Example 5 uses conventional CP1801X polycarboxylate water reducer, which contains neither cationic groups nor four-arm star-shaped polycarboxylate polyether branched molecular chains. The dispersibility of cement particles is poor, the fluidity of the pure slurry is low, and the compressive strength of the cement is poor.

Claims

1. A cement-based grouting material containing a modified polycarboxylate water-reducing agent, characterized in that: The invention comprises the following raw materials in parts by weight: 350-450 parts of cement, 50-100 parts of fly ash, 520-650 parts of sand, 220-300 parts of water, 4-12 parts of hyperbranched modified polycarboxylic acid water reducer, and 60-110 parts of steel fiber; The preparation process of the hyperbranched modified polycarboxylic acid water reducer comprises the following steps: adding pentaerythritol tetra(thiobromoethylpropionate) acetate, acrylic acid, acrylate cationic polyethylene glycol monomethyl ether and 2,2'-bipyridine to an ethanol aqueous solution, adding sodium hydroxide after mixing, freezing in liquid nitrogen, vacuumizing and thawing, then adding cuprous bromide, reacting in a nitrogen range, adding acetone after the reaction, precipitating a precipitate, filtering, washing and drying to obtain the hyperbranched modified polycarboxylic acid water reducer.

2. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 1, characterized in that: The molar ratio of pentaerythritol tetrakis(thiobromoethylpropionate) acetate, acrylic acid, and acrylate cationic polyethylene glycol monomethyl ether is 1:(30-70):(12-28).

3. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 1, characterized in that: The volume fraction of the ethanol aqueous solution is 60-80%.

4. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 1, characterized in that: The solution pH is adjusted to 8-9 by adding sodium hydroxide.

5. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 1, characterized in that: The reaction temperature is 75-90°C and the reaction time is 24-36h.

6. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 2, characterized in that: The preparation method of pentaerythritol tetrakis (thiobromoethyl propionate) acetate is as follows: pentaerythritol tetrakisthioacetate, 2-bromoethyl acrylate and benzoin dimethyl ether are added to tetrahydrofuran, and the mixture is irradiated under a 200-500W ultraviolet lamp for reaction for 30-60 minutes in a nitrogen atmosphere, and the solution is concentrated, washed and dried to obtain pentaerythritol tetrakis (thiobromoethyl propionate) acetate.

7. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 6, characterized in that: The molar ratio of pentaerythritol tetrathioglycolate, 2-bromoethyl acrylate and benzoin dimethyl ether is 1:(4-4.8):(0.04-0.05).

8. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 2, characterized in that: The preparation method of the acrylic acid ester cationic polyethylene glycol monomethyl ether is as follows: (1) adding polyethylene glycol monomethyl ether, N,N-dimethylglycine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 4-dimethylaminopyridine to N,N-dimethylformamide, reacting at room temperature for 12-18 hours, distilling under reduced pressure, washing, and drying to obtain tertiary amino polyethylene glycol monomethyl ether; (2) Add tertiary amino polyethylene glycol monomethyl ether and 2-bromoethyl acrylate in a molar ratio of 1:(4.5-6.8) to N,N-dimethylformamide, react at 100-130° C. for 24-48 hours, remove N,N-dimethylformamide by vacuum distillation, wash with n-hexane, and dry to obtain acrylate cationic polyethylene glycol monomethyl ether.

9. The cement-based grouting material containing modified polycarboxylate water-reducing agent according to claim 8, characterized in that: The molar ratio of polyethylene glycol monomethyl ether, N,N-dimethylglycine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine in (1) is 1:(2.5-3.2):(2.5-3.2):(0.2-0.26).

10. A process for preparing a cement-based grouting material containing a modified polycarboxylate water-reducing agent according to any one of claims 1 to 9, characterized in that: Add cement, fly ash, sand, water, hyperbranched modified polycarboxylate water reducer and steel fiber into a mixing barrel and stir for 6-10 minutes to obtain a cement-based grouting material containing the modified polycarboxylate water reducer.

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