High-strength composite cement grinding aid and preparation method thereof

Abstract

The application relates to the field of building materials, and particularly discloses a high-strength composite cement grinding aid and a preparation method thereof.A high-strength composite cement grinding aid comprises the following components: triethanolamine, pentaerythritol, methylhydroxyethyl cellulose, sodium fluorosilicate, molasses and water.A high-strength composite cement grinding aid is prepared by mixing the components in sequence.The grinding aid has the advantages of good grinding effect and high late-strength of the prepared cement mortar; in addition, the preparation method is simple and convenient, and easy for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building materials, in particular to a high-strength composite cement grinding aid and a preparation method thereof. BACKGROUND

[0002] High-strength concrete is a kind of concrete with high durability and high strength, which can adapt to the development of modern engineering structure to large-span heavy load and withstand harsh environmental conditions, and is one of the main directions of future concrete development.

[0003] Concrete grinding aid is a kind of cement grinding aid, which is an important component in the preparation of concrete and is crucial to the formation of high-strength concrete. Concrete grinding aid generally participates in the grinding process of cement, and by adding concrete grinding aid, the surface energy of ultra-fine particles generated during cement grinding is reduced, the agglomeration and recrystallization of ultra-fine particles under the action of mechanical force are prevented, and the grinding efficiency and the grinding fineness of cement are affected.

[0004] The conventional concrete grinding aid on the market is mainly based on triethanolamine, which has good grinding performance, and can accelerate the hydration process of tricalcium silicate when added to cement, so that the cement mortar has good early strength. However, due to the accelerated hydration process of cement, the setting time of cement is shortened, and a large amount of hydration products is formed in a short time, which can easily lead to too fast crystallization speed and uneven distribution in the cement, and even cause more local large pores, so that the concrete cannot be supported by enough hydration products in the later stage, resulting in a decrease in the later strength of the concrete. Therefore, there is still room for improvement. SUMMARY

[0005] In order to improve the grinding performance of the grinding aid and enhance the later strength of the concrete, the present application provides a high-strength composite cement grinding aid and a preparation method thereof.

[0006] In the first aspect, the present application provides a high-strength composite cement grinding aid, which adopts the following technical scheme:

[0007] A high-strength composite cement grinding aid, comprising the following components in mass fraction:

[0008] Triethanolamine 10-30 parts;

[0009] Pentaerythritol 7-15 parts;

[0010] Cellulose derivative 2-6 parts;

[0011] Sodium fluorosilicate 5-7 parts;

[0012] Molasses 7-15 parts;

[0013] Water 50-70 parts.

[0014] By adopting the technical scheme, the addition of triethanolamine, pentaerythritol and polar nonionic surfactant is conducive to reducing the surface energy of cement particles, reducing the van der Waals force between the cement particles, reducing the particle agglomeration, improving the grinding efficiency, making the ground cement have a certain fineness, and fully hydrating in the later construction process to improve the strength of the mortar; by mixing cellulose derivatives, sodium fluorosilicate and molasses with water, the hydration of tricalcium silicate in the cement is delayed, the strength of the mortar in the later stage is improved, and the phenomenon of local large pores in the mortar due to excessive hydration speed is not prone to occur.

[0015] By adding cellulose derivatives, sodium fluorosilicate and molasses in combination with triethanolamine and pentaerythritol, the cellulose derivatives, sodium fluorosilicate and molasses are conducive to strengthening the grinding efficiency of triethanolamine and pentaerythritol, and further promoting the grinding efficiency of the grinding aid by breaking the recrystallized cement particles under the action of mechanical force, so that the cement powder prepared per unit time is finer, which is conducive to full hydration of the cement and further improves the strength of the cement; the finer ground cement is not prone to recrystallization to cause the agglomeration of the ground particles, resulting in insufficient hydration of the cement and affecting the strength of the cement.

[0016] Preferably, the triethanolamine is modified triethanolamine, and the modification method of the modified triethanolamine is: adding triethanolamine and a catalyst into a container, continuously stirring, heating to 115-150°C, and then adding maleic amide acid and diethylene glycol dibenzoate into the container in three times, fully reacting, and obtaining the modified triethanolamine; wherein the mass ratio of triethanolamine, maleic amide acid and diethylene glycol dibenzoate is (4-6):(1-2):1.

[0017] By adopting the above technical scheme, the triethanolamine is modified, the triethanolamine reacts with maleic amide acid and diethylene glycol dibenzoate under the catalysis of the catalyst to increase the polar groups on the surface of the triethanolamine, form more covalent bonds and hydrogen bonds, and be adsorbed on the surface of the cement particles, so that the ground cement repels each other and is not prone to agglomeration, which is conducive to improving the cement grinding efficiency and the dispersity of the cement in the mortar, preventing the cement from agglomerating during hydration, preventing the mortar from having local large pores due to water evaporation during the later curing process, and enhancing the later strength of the cement mortar without affecting the early strength of the cement mortar.

[0018] Preferably, the catalyst is sulfonic acid and its derivatives.

[0019] By adopting the above technical scheme, the above reaction is catalyzed by a specific type of catalyst, which is conducive to preparing modified triethanolamine with high purity and good quality.

[0020] Preferably, the cellulose derivative includes one or more of methylhydroxyethyl cellulose, cellulose acetate butyrate, hydroxyethyl cellulose acetate butyrate.

[0021] By adopting the technical scheme, the cellulose derivative is adsorbed on the surface of the cement particles to form a high-molecular hydration film, the cement curing speed is delayed, and the cement is not easily prematurely hydrated to affect the later strength of the cement mortar.

[0022] Preferably, the cellulose derivative includes methylhydroxyethyl cellulose and cellulose acetate butyrate in a mass ratio of (1-2):(1-4).

[0023] By adopting the technical scheme, the methylhydroxyethyl cellulose and the cellulose acetate butyrate in the specific ratio are synergistically compounded, the cement hydration speed is delayed, the early strength of the cement is not affected, and the cement is not easily collapsed during construction.

[0024] Preferably, the molasses includes one or more of beet molasses, cane molasses, grape molasses, and corn molasses.

[0025] By adopting the technical scheme, the one or more substances are used as the molasses, the hydration of the cement slurry is inhibited through complexation with the aluminum salt in the cement, the cement is not easily prematurely hydrated to affect the later strength of the cement mortar.

[0026] Preferably, the molasses is composed of beet molasses and cane molasses in a mass ratio of (3-7):(4-8).

[0027] By adopting the technical scheme, the beet molasses and the cane molasses in the specific ratio are used as the molasses, the cement hydration time is delayed, the early strength of the cement is not affected, and the cement is not easily collapsed during construction.

[0028] In a second aspect, the application provides a preparation method of a high-strength composite cement grinding aid.

[0029] The preparation method of the high-strength composite cement grinding aid includes the following steps.

[0030] Step 1: triethanolamine and pentaerythritol are added to a reaction kettle integrating condensation reflux and stirring, continuous stirring is performed, heating reflux is performed for 8-12 hours, a mixture is obtained, and the mixture is cooled for standby;

[0031] Step 2: the mixture obtained in step 1 is added to a container, a cellulose derivative, sodium fluorosilicate, molasses, and water are added, and stirring is performed, thereby obtaining the high-strength composite cement grinding aid.

[0032] By adopting the technical scheme, the high-strength composite cement grinding aid is prepared according to the above steps, which is beneficial to prepare the high-strength composite cement grinding aid with good grinding degree, high strength and good quality.

[0033] In summary, the present application has the following beneficial effects:

[0034] 1. By adding triethanolamine, pentaerythritol and polar nonionic surfactant, the surface energy of cement particles is reduced, the van der Waals force between cement particles is reduced, the particle agglomeration is reduced, and the grinding efficiency is improved; by mixing cellulose derivative, sodium fluorosilicate, molasses and water, the hydration of tricalcium silicate in cement is delayed, the late strength of mortar is improved, and the phenomenon of local large pores in mortar due to too fast hydration speed is not prone to occur.

[0035] 2. By adding cellulose derivative, sodium fluorosilicate, molasses, triethanolamine and pentaerythritol, the cellulose derivative, sodium fluorosilicate and molasses are beneficial to strengthen the grinding efficiency of triethanolamine and pentaerythritol, further promote the grinding efficiency of the grinding aid by breaking the cement particles recrystallized under mechanical force, and further improve the cement strength by preparing finer cement powder in unit time and promoting the hydration of cement.

[0036] 3. By modifying triethanolamine, triethanolamine reacts with maleic acid and diethylene glycol dibenzoate under the catalysis of a catalyst to increase the polar groups on the surface of triethanolamine, form more covalent bonds and hydrogen bonds adsorbed on the surface of cement particles, make the ground cement repel each other and not easy to agglomerate, improve the cement grinding efficiency and the dispersion degree of cement in mortar, prevent the cement from agglomerating and hydrating during hydration, reduce the occurrence of local large pores in cement mortar, and enhance the late strength of cement mortar without affecting the early strength of cement mortar. DETAILED DESCRIPTION

[0037] The present application is further described in detail below in combination with examples.

[0038] The raw materials of the following examples and comparative examples are all from the market, and are as follows:

[0039] The CAS number of triethanolamine is 102-71-6;

[0040] The CAS number of ethanolamine is 141-43-5;

[0041] The CAS number of pentaerythritol is 115-77-5;

[0042] The CAS number of borax is 1303-96-4;

[0043] The CAS number of microcrystalline cellulose is 9004-34-6;

[0044] The CAS number of sucrose is 57-50-1;

[0045] The CAS number of propylene glycol is 57-55-6;

[0046] The CAS number of methylhydroxyethyl cellulose is 9032-42-2;

[0047] The CAS number of methyl cellulose is 9004-67-5;

[0048] The CAS number of ethyl cellulose is 9004-57-3;

[0049] The CAS number of cellulose acetate butyrate is 9004-36-8;

[0050] The CAS number of maleic anhydride is 108-31-6;

[0051] The CAS number of vinyl acetate is 108-05-4;

[0052] The CAS number of sodium fluorosilicate is 16893-85-9;

[0053] The CAS number of toluenesulfonic acid is 104-15-4;

[0054] The CAS number of maleamic acid is 557-24-4;

[0055] The CAS number of diethylene glycol dibenzoate is 120-55-8;

[0056] The sugar beet molasses was purchased from Shanghai Yiji Industry Co., Ltd.

[0057] The sugar cane molasses was purchased from Shanghai Tingruo Chemical Co., Ltd.

[0058] The citrus molasses and corn molasses were purchased from Jiangsu Caiwei Biological Technology Co., Ltd.

[0059] Preparation Example 1

[0060] A modification method of triethanolamine is as follows:

[0061] Into a four-necked flask, 40 g of triethanolamine and 0.5 g of catalyst were added, and stirring was continuously carried out at a rotation speed of 100 r / min, and the temperature of the flask was heated to 115℃; then 3.4 g of maleic acid amide and 3.4 g of diethylene glycol dibenzoate were added into the flask; after 30 minutes of reaction, 3.3 g of maleic acid amide and 3.3 g of diethylene glycol dibenzoate were added; after another 30 minutes of reaction, 3.3 g of maleic acid amide and 3.3 g of diethylene glycol dibenzoate were added; after the addition of maleic acid amide and diethylene glycol dibenzoate was completed, the reaction was continued for 4 hours, and modified triethanolamine was obtained.

[0062] In the present preparation example, the catalyst is sulfonic acid and its derivative, specifically toluene sulfonic acid.

[0063] Preparation Example 2

[0064] A method for modifying triethanolamine, specifically as follows:

[0065] Into a four-necked flask, 60 g of triethanolamine and 0.5 g of toluene sulfonic acid were added, and stirring was continuously carried out at a rotation speed of 100 r / min, and the temperature of the flask was heated to 150℃; then 6.8 g of maleic acid amide and 6.8 g of diethylene glycol dibenzoate were added into the flask; after 30 minutes of reaction, 6.6 g of maleic acid amide and 6.6 g of diethylene glycol dibenzoate were added; after another 30 minutes of reaction, 6.6 g of maleic acid amide and 6.6 g of diethylene glycol dibenzoate were added; after the addition of maleic acid amide and diethylene glycol dibenzoate was completed, the reaction was continued for 6 hours, and modified triethanolamine was obtained.

[0066] In the present preparation example, the catalyst is sulfonic acid and its derivative, specifically toluene sulfonic acid.

[0067] Preparation Example 3

[0068] A method for modifying triethanolamine, specifically as follows:

[0069] Into a four-necked flask, 50 g of triethanolamine and 0.5 g of toluene sulfonic acid were added, and stirring was continuously carried out at a rotation speed of 100 r / min, and the temperature of the flask was heated to 130℃; then 5.1 g of maleic acid amide and 5.1 g of diethylene glycol dibenzoate were added into the flask; after 30 minutes of reaction, 4.95 g of maleic acid amide and 4.95 g of diethylene glycol dibenzoate were added; after another 30 minutes of reaction, 4.95 g of maleic acid amide and 4.95 g of diethylene glycol dibenzoate were added; after the addition of maleic acid amide and diethylene glycol dibenzoate was completed, the reaction was continued for 5 hours, and modified triethanolamine was obtained.

[0070] In the present preparation example, the catalyst is sulfonic acid and its derivative, specifically toluene sulfonic acid.

[0071] Comparative Preparation Example 1

[0072] Into a four-necked flask, 50g of triethanolamine, 0.5g of toluene sulfonic acid were added, and the flask was continuously stirred at a speed of 100r / min, and the temperature of the flask was heated to 130℃, then 5.1g of maleic amide acid and 5.1g of diethylene glycol dibenzoate were added into the flask, after 30 minutes of reaction, 4.95g of maleic amide acid and 4.95g of diethylene glycol dibenzoate were added, after another 30 minutes of reaction, 4.95g of maleic amide acid and 4.95g of diethylene glycol dibenzoate were added, and after the addition of maleic anhydride and diethylene glycol dibenzoate was completed, the reaction was continued for 5 hours, to obtain the modified triethanolamine.

[0073] In this preparation example, the catalyst is sulfonic acid and its derivatives, specifically toluene sulfonic acid.

[0074] The difference between this example and Example 3 is that an equal amount of maleic anhydride is used to replace maleic amide acid.

[0075] Comparative Preparation Example 2

[0076] Into a four-necked flask, 50g of triethanolamine, 0.5g of toluene sulfonic acid were added, and the flask was continuously stirred at a speed of 100r / min, and the temperature of the flask was heated to 130℃, then 5.1g of maleic amide acid and 5.1g of diethylene glycol dibenzoate were added into the flask, after 30 minutes of reaction, 4.95g of maleic amide acid and 4.95g of diethylene glycol dibenzoate were added, after another 30 minutes of reaction, 4.95g of maleic amide acid and 4.95g of diethylene glycol dibenzoate were added, and after the addition of maleic amide acid and vinyl acetate was completed, the reaction was continued for 5 hours, to obtain the modified triethanolamine.

[0077] In this preparation example, the catalyst is sulfonic acid and its derivatives, specifically toluene sulfonic acid.

[0078] The difference between this example and Example 3 is that an equal amount of maleic anhydride is used to replace maleic amide acid.

[0079] Example 1

[0080] A high-strength composite cement grinding aid is composed of the following components by mass:

[0081] Triethanolamine 10kg; pentaerythritol 7kg; cellulose derivative 2kg; sodium fluorosilicate 5kg; molasses 7kg; water 50kg.

[0082] In this example, the cellulose derivative is obtained by mixing 1kg of methylhydroxyethyl cellulose and 1kg of cellulose acetate butyrate; the molasses is obtained by mixing 3kg of beet molasses and 4kg of sugarcane molasses.

[0083] A method for preparing a high-strength composite cement grinding aid, comprising the following steps:

[0084] Step 1, add triethanolamine and pentaerythritol into a reaction kettle with condensation reflux and stirring integrated, continuously stir at a speed of 150 r / min, heat to 250℃, reflux for 8h, obtain a mixture, cool at room temperature and reserve;

[0085] Step 2, add the mixture obtained in step 1 into a stirrer, add methylhydroxyethyl cellulose, cellulose acetate butyrate, beet molasses, cane molasses, sodium fluorosilicate and water, stir at a speed of 150 r / min for 20 minutes, obtain a high-strength composite cement grinding aid.

[0086] Example 2

[0087] A high-strength composite cement grinding aid is composed of the following components by mass:

[0088] Triethanolamine 30 kg; pentaerythritol 15 kg; cellulose derivative 6 kg; sodium fluorosilicate 7 kg; molasses 15 kg; water 70 kg.

[0089] In this example, the cellulose derivative is obtained by mixing 2 kg of methylhydroxyethyl cellulose and 4 kg of cellulose acetate butyrate; the molasses is obtained by mixing 7 kg of beet molasses and 8 kg of cane molasses.

[0090] A method for preparing a high-strength composite cement grinding aid, comprising the following steps:

[0091] Step 1, add triethanolamine and pentaerythritol into a reaction kettle with condensation reflux and stirring integrated, continuously stir at a speed of 150 r / min, heat to 250℃, reflux for 8h, obtain a mixture, cool at room temperature and reserve;

[0092] Step 2, add the mixture obtained in step 1 into a stirrer, add methylhydroxyethyl cellulose, cellulose acetate butyrate, beet molasses, cane molasses, sodium fluorosilicate and water, stir at a speed of 150 r / min for 20 minutes, obtain a high-strength composite cement grinding aid.

[0093] Example 3

[0094] A high-strength composite cement grinding aid is composed of the following components by mass:

[0095] Triethanolamine 20 kg; pentaerythritol 11 kg; cellulose derivative 4 kg; sodium fluorosilicate 6 kg; molasses 11 kg; water 60 kg.

[0096] In this example, the cellulose derivative is obtained by mixing 1.5 kg of methylhydroxyethyl cellulose and 2.5 kg of cellulose acetate butyrate; the molasses is obtained by mixing 5 kg of beet molasses and 6 kg of cane molasses.

[0097] A preparation method of a high-strength composite cement grinding aid, comprising the following steps:

[0098] Step 1, add triethanolamine and pentaerythritol into a reaction kettle with condensation reflux and stirring integrated, continuously stir at a speed of 150 r / min, heat to 250 DEG C, reflux for 8 h, obtain a mixture, cool at room temperature and reserve;

[0099] Step 2, add the mixture obtained in step 1 into a container, add methylhydroxyethyl cellulose, cellulose acetate butyrate, sugar beet molasses, cane molasses, sodium fluorosilicate and water, stir at a speed of 150 r / min for 20 min, and obtain a high-strength composite cement grinding aid.

[0100] Example 4

[0101] A high-strength composite cement grinding aid, which is different from example 3 in that methyl cellulose is used to replace methylhydroxyethyl cellulose in equal amount.

[0102] Example 5

[0103] A high-strength composite cement grinding aid, which is different from example 3 in that ethyl cellulose is used to replace cellulose acetate butyrate in equal amount.

[0104] Example 6

[0105] A high-strength composite cement grinding aid, which is different from example 3 in that citrus molasses is used to replace sugar beet molasses in equal amount.

[0106] Example 7

[0107] A high-strength composite cement grinding aid, which is different from example 3 in that corn molasses is used to replace cane molasses in equal amount.

[0108] Example 8

[0109] A high-strength composite cement grinding aid, which is different from example 3 in that triethanolamine is modified triethanolamine and is prepared by preparation example 1;

[0110] Example 9

[0111] A high-strength composite cement grinding aid, which is different from example 3 in that triethanolamine is modified triethanolamine and is prepared by preparation example 2;

[0112] Example 10

[0113] A high-strength composite cement grinding aid, which is different from example 3 in that triethanolamine is modified triethanolamine and is prepared by preparation example 3;

[0114] Example 11

[0115] A high-strength composite cement grinding aid, which is different from Example 3 in that the triethanolamine is modified triethanolamine and is prepared from Comparative Preparation Example 1;

[0116] Example 12

[0117] A high-strength composite cement grinding aid, which is different from Example 3 in that the triethanolamine is modified triethanolamine and is prepared from Comparative Preparation Example 2;

[0118] Comparative Example 1

[0119] A high-strength composite cement grinding aid, which is different from Example 3 in that the triethanolamine is modified triethanolamine and is prepared from Comparative Preparation Example 2;

[0120] Triethanolamine 20 kg; pentaerythritol 11 kg.

[0121] A method for preparing a high-strength composite cement grinding aid, which is as follows:

[0122] Into a reaction kettle integrating condensation reflux and stirring, triethanolamine and pentaerythritol are added, and continuous stirring is carried out at a rotation speed of 150 r / min, heating reflux is carried out for 10 h, and cooling is carried out at room temperature, and a high-strength composite cement grinding aid is obtained.

[0123] Comparative Example 2

[0124] A high-strength composite cement grinding aid, which is different from Example 3 in that an equal amount of ethanolamine is used to replace triethanolamine.

[0125] Comparative Example 3

[0126] A high-strength composite cement grinding aid, which is different from Example 3 in that an equal amount of propylene glycol is used to replace pentaerythritol.

[0127] Comparative Example 4

[0128] A high-strength composite cement grinding aid, which is different from Example 3 in that an equal amount of microcrystalline cellulose is used to replace cellulose derivative.

[0129] Comparative Example 5

[0130] A high-strength composite cement grinding aid, which is different from Example 3 in that an equal amount of borax is used to replace sodium fluorosilicate.

[0131] Comparative Example 6

[0132] A high-strength composite cement grinding aid, which is different from Example 3 in that an equal amount of sucrose is used to replace molasses.

[0133] Experiment 1 Cement fineness

[0134] The cement clinker (portland cement) is first crushed into cement particles of 10-40 mm using a jaw crusher, then 10 kg of the cement particles are mixed with 4 g of the grinding aid, and put into a cement grinding mill to grind for 30 minutes at a speed of 280 r / min to obtain a composite cement. Then, the fineness of the cement is tested according to GB / T 1345-2005 "Cement Fineness Test Method (Screen Analysis Method)" using a FSY150-E negative pressure screen analyzer, and the distribution of the cement with a fineness greater than 80 μm and less than 45 μm is recorded. The more cement with a grinding fineness less than 45 μm, the better the grinding performance of the grinding aid; the more cement with a grinding fineness greater than 80 μm, the weaker the grinding performance of the grinding aid. The FSY150-E negative pressure screen analyzer is purchased from Hebei Shengmingyang Instrument and Equipment Co., Ltd.

[0135] The above experimental data are shown in Table 1.

[0136] Experimental 2 Cement Strength

[0137] The cement clinker (portland cement) is first crushed into cement particles of 10-40 mm using a jaw crusher, then 10 kg of the cement particles are mixed with 4 g of the grinding aid, and put into a cement grinding mill to grind for 30 minutes at a speed of 280 r / min to obtain a composite cement. Then, the fineness of the cement is tested according to GB / T 1345-2005 "Cement Fineness Test Method (Screen Analysis Method)" using a FSY150-E negative pressure screen analyzer, and the distribution of the cement with a fineness greater than 80 μm and less than 45 μm is recorded. The more cement with a grinding fineness less than 45 μm, the better the grinding performance of the grinding aid; the more cement with a grinding fineness greater than 80 μm, the weaker the grinding performance of the grinding aid. The FSY150-E negative pressure screen analyzer is purchased from Hebei Shengmingyang Instrument and Equipment Co., Ltd.

[0138] The above experimental data are shown in Table 1.

[0139] Table 1

[0140]

[0141] According to the data comparison of Example 3 and Comparative Example 1 in Table 1, the early (3d) compressive strength of the cement mortar prepared by using the grinding aid prepared by adding triethanolamine, pentaerythritol, cellulose derivative, sodium fluorosilicate, molasses and water in Example 3 is 23.13 MPa, the late (28d) compressive strength is 45.96 MPa, the early (3d) flexural strength is 4.83 MPa, the late (28d) flexural strength is 7.82 MPa, the cement fineness of less than 45 μm is 44.71%, and the cement fineness of more than 80 μm is 8.32%; the late compressive strength and flexural strength of the cement mortar prepared by using the grinding aid prepared by adding triethanolamine and pentaerythritol in Comparative Example 1 are obviously lower than those of Example 3, and the cement fineness is coarser than that of Example 3. It is proved that although the addition of triethanolamine and pentaerythritol is beneficial to improving the cement grinding fineness, it also easily has a great influence on the cement hydration, so that the late strength of the cement mortar prepared by using the cement is greatly affected, and the preparation of the grinding aid by simultaneously compounding cellulose derivative, sodium fluorosilicate, molasses and water is beneficial to well reducing the influence of triethanolamine and pentaerythritol on the late strength of the cement mortar.

[0142] According to the data comparison of Example 3 and Comparative Examples 2-6 in Table 1, in Comparative Examples 2-6, the grinding aid is prepared by replacing triethanolamine, pentaerythritol, cellulose derivative, sodium fluorosilicate, molasses and water with equal amount of ethanolamine, propylene glycol, microcrystalline cellulose, borax and sucrose, respectively, the early and late compressive strength and flexural strength of the cement mortar prepared by using the grinding aid are lower, and the cement particle size after grinding is coarser. It is proved that the simultaneous compounding of triethanolamine, pentaerythritol, cellulose derivative, sodium fluorosilicate and molasses is beneficial to preparing the grinding aid which can effectively improve the early and late compressive strength and flexural strength and has high grinding efficiency. In addition, the cement grinding effect of Comparative Example 2-3 is far worse than that of Comparative Example 1, which proves that only the simultaneous compounding of triethanolamine and pentaerythritol is beneficial to better improving the cement grinding fineness, and the replacement of any other grinding agent easily has a great influence on the cement grinding fineness; and the cement grinding fineness of Comparative Examples 4-6 is similar to that of Comparative Example 1, which proves that only the simultaneous compounding of cellulose derivative, sodium fluorosilicate and molasses is beneficial to further promoting the cement grinding fineness, and the replacement of any one of them can only have the effect of retarding the setting to alleviate the influence of the cement hydration on the late strength of the cement mortar, but cannot further promote the cement grinding fineness.

[0143] According to the data comparison of example 3 and example 8-12 in table 1, it can be obtained that the grinding aids prepared by using the modified triethanolamine with maleamic acid and diethylene glycol dibenzoate have better grinding fineness, and the early and late compressive strength and flexural strength of the cement mortar prepared by using the grinding aids are higher than that of example 3; according to the data comparison of example 11-12, it can be obtained that the performance of the grinding aids prepared by using equal amount of maleic anhydride and vinyl acetate instead of maleamic acid and diethylene glycol dibenzoate is decreased. It is proved that the modification of triethanolamine by adding maleamic acid and diethylene glycol dibenzoate is beneficial to increase the polar groups on the surface of triethanolamine, form more covalent bonds and hydrogen bonds, make the interaction of each functional group, adsorb on the surface of cement particles, improve the cement grinding efficiency and the dispersion degree of cement in mortar, reduce the occurrence of local large pores in cement mortar, enhance the late strength of cement mortar, and at the same time, do not affect the early strength of cement mortar. Any substitution of one of them cannot achieve the above effects.

[0144] According to the data comparison of example 4-7 in table 1, it can be obtained that the synergistic compounding of methylhydroxyethyl cellulose and cellulose acetate butyrate in a specific ratio in example 4-5 is beneficial to delay the hydration speed of cement, and does not easily affect the early strength of cement, so that the cement does not easily appear to collapse in the process of construction; the sugar beet molasses and sugarcane molasses as molasses in example 6-7 is beneficial to delay the hydration time of cement, and does not easily affect the early strength of cement, so that the cement does not easily appear to collapse in the process of construction.

[0145] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and the person skilled in the art can make a modification of the present embodiments without creative contribution according to the needs after reading the present specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A high-strength composite cement grinding aid, characterized in that, The components include the following parts by mass: 10-30 parts of triethanolamine; Pentaerythritol 7-15 parts; 2-6 parts of cellulose derivatives; 5-7 parts of sodium fluorosilicate; 7-15 parts molasses; 50-70 parts water; The triethanolamine is a modified triethanolamine. The modification method of the modified triethanolamine is as follows: triethanolamine and catalyst are added to a container, stirred continuously, heated to 115-150°C, and then maleic acid and diethylene glycol dibenzoate are added to the container in three portions. After the reaction is complete, the modified triethanolamine is obtained. The mass ratio of triethanolamine, maleic acid and diethylene glycol dibenzoate is (4-6):(1-2):

1.

2. The high-strength composite cement grinding aid according to claim 1, characterized in that, The catalyst is sulfonic acid and its derivatives.

3. The high-strength composite cement grinding aid according to claim 1, characterized in that, The cellulose derivative is composed of methyl hydroxyethyl cellulose and cellulose acetate butyrate in a mass ratio of (1-2):(1-4).

4. The high-strength composite cement grinding aid according to claim 1, characterized in that, The molasses is composed of beet molasses and sugarcane molasses in a mass ratio of (3-7):(3-8).

5. A method for preparing a high-strength composite cement grinding aid as described in any one of claims 1-4, characterized in that: Includes the following steps: Step 1: Add triethanolamine and pentaerythritol to the reaction vessel that integrates reflux and stirring, stir continuously, add sodium fluorosilicate, heat under reflux for 8-12 hours to obtain a mixture, and cool it for later use. Step 2: Add the mixture obtained in Step 1 to the container, then add cellulose derivative, molasses, and water, and stir to obtain high-strength composite cement grinding aid.

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