Early-strength cement grinding aid and preparation method thereof

Abstract

The application provides an early-strength cement grinding aid, which comprises the following components in parts by weight: 16-28 parts of silica microparticles, 8-14 parts of alumina microparticles, 14-32 parts of calcium carbonate microparticles, 0.2-0.5 parts of a particle structure control agent, 0.5-2 parts of a thickening agent, 1-10 parts of malt dextrin, 1-4 parts of sodium dihydrogen phosphate, 2-6 parts of disodium hydrogen phosphate, 20-50 parts of an alcohol organic substance and 70-100 parts of water. Compared with the prior art, the application sets the particle structure control agent, and the application can control the formation of small and dispersed calcium silicate hydrate crystal nuclei and calcium silicate-aluminate hydrate crystal nuclei, promote the formation of cement calcium silicate hydrate and calcium silicate-aluminate hydrate crystals, and greatly improve the early strength of the cement. In addition, the application further provides a preparation method of the early-strength cement grinding aid.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to an early-strength cement grinding aid and its preparation method. Background Technology

[0002] In the cement production process, cement grinding is the most energy-intensive step. To reduce production costs, save energy, and improve grinding efficiency, one of the most effective methods is to add a small amount of cement grinding aid during the grinding process. Because grinding aids can significantly reduce the surface energy of the grinding powder, improve grinding efficiency, and also improve cement quality, they have become a hot topic in the field of engineering materials research and development, possessing significant theoretical importance and broad application prospects.

[0003] In the cement grinding process, triethanolamine, a key raw material for grinding aids in existing technologies, not only has excellent grinding aid properties but also early strength-enhancing effects, thus it is widely used as an early-strength grinding aid in production. However, in industrial practice, the inventors have discovered that cement obtained with early-strength grinding aids containing triethanolamine has some adaptability issues, such as insufficient early strength, affecting physical properties like standard consistency and setting time during use, and poor compatibility with water-reducing agents; that is, the early strength of cement produced with early-strength cement grinding aids made from triethanolamine needs to be improved.

[0004] Therefore, the present invention provides an early-strength cement grinding aid and its preparation method. Summary of the Invention

[0005] To address the issues of unstable early strength, negative impact on cement physical properties, and poor compatibility with water-reducing agents in existing early-strength cement grinding aids, this invention provides an early-strength cement grinding aid and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] An early-strength cement grinding aid, wherein the early-strength cement grinding aid solution is expressed in the following parts by weight:

[0008]

[0009] Preferably, the particle size range of the silica microparticles is 100-1000 nm.

[0010] Preferably, the particle size range of the alumina microparticles is 100-1000 nm.

[0011] Preferably, the particle size range of the calcium carbonate microparticles is 100-1000 nm.

[0012] It should be noted that in the early-strength grinding aid of the present invention, the particle size range of silica microparticles, alumina microparticles, and calcium carbonate microparticles is 100-1000 nm. The weight ratio of silica microparticles, alumina microparticles, and calcium carbonate microparticles can be 2:1:4-2:1:1, preferably 2:1:2.

[0013] Preferably, the particle structure control agent is a mixture of a first composition and a second composition. The first composition consists of one or any two or three of sodium polyacrylate, polyacrylamide, and polycarboxylate superplasticizer polymer, and the second composition consists of one or any two or more of sodium dodecanoate. The mass ratio of the aforementioned polymer to linear sodium alkylate is 1:1 to 4:1. The particle structure control agent effectively controls the crystal formation process during the formation of hydrated calcium silicate and hydrated calcium aluminosilicate crystals, forming small and uniformly dispersed crystals, thereby providing numerous crystal nuclei during cement hydration and accelerating the formation rate of cement hydrated calcium silicate and hydrated calcium aluminosilicate crystals.

[0014] Preferably, the thickener is at least one of hydroxypropyl methylcellulose, sodium alginate, and sodium carboxymethyl cellulose, or a mixture of any two or more of these three. The thickener increases the solution viscosity to prevent the precipitation of silica microparticles, alumina microparticles, and calcium carbonate microparticles. Simultaneously, maltodextrin adsorbs onto the surface of the silica microparticles, alumina microparticles, and calcium carbonate microparticles to prevent particle aggregation, thus stabilizing the microparticles.

[0015] Preferably, the alcoholic organic compound is at least one of ethylene glycol, polyethylene glycol, glycerol, and polyglycerol, or a mixture of any two or three of them, or a mixture of all four.

[0016] Preferably, when the alcoholic organic compound contains polyethylene glycol, the molecular weight of the polyethylene glycol is in the range of 200-2000;

[0017] When the organic alcohol contains polyglycerol, the polyglycerol is a polymer in any form with a molecular weight range of 200-1000. Specifically, polyethylene glycol has a molecular weight range of 200-2000, and the polyglycerol is a polymer in any form with a molecular weight range of 200-1000. Organic alcohols have excellent grinding properties for cement.

[0018] Preferably, the pH range of the early-strength cement grinding aid solution is 6-8. By adjusting the ratio of sodium dihydrogen phosphate to disodium hydrogen phosphate, the silica microparticles, alumina microparticles, and calcium carbonate microparticles remain stable in the solution within the pH range of the early-strength cement grinding aid solution, preventing hydrolysis and other denaturation.

[0019] The present invention also provides a method for preparing an early-strength cement grinding aid as described above, characterized by comprising the following steps:

[0020] Step 1: Take 0.5-2 parts thickener, 1-10 parts maltodextrin, 1-4 parts sodium dihydrogen phosphate, and 2-6 parts disodium hydrogen phosphate and dissolve them in 70-100 parts water. Soak for at least 12 hours to obtain a soaking solution.

[0021] Step 2: Take 16-28 parts of silica microparticles, 8-14 parts of alumina microparticles, and 14-32 parts of calcium carbonate microparticles and place them in a mixer to mix evenly. Then add them to the soaking solution in step 1. At the same time, use a high-speed shear machine to emulsify at a speed of 5000-12000 rpm for 30 minutes to obtain a homogeneous emulsion.

[0022] The third step involves adding 0.2-0.5 parts of particle structure control agent and 20-50 parts of alcohol organic matter to the homogenized emulsion from the second step, and then stirring until a stable solution is formed to obtain an early-strength cement grinding aid solution.

[0023] As described above, the early-strength cement grinding aid and its preparation method disclosed in this invention have the following beneficial effects:

[0024] Compared with existing technologies, this invention utilizes the aforementioned early-strength cement grinding aid. The early-strength agent component in this invention uses silica microparticles, alumina microparticles, and calcium carbonate microparticles. Under a certain mixing ratio, these microparticles rapidly dissolve in the cement mixture, forming tiny and dispersed hydrated calcium silicate and hydrated calcium aluminosilicate crystal nuclei under the action of a particle structure control agent. This promotes the crystallization of hydrated calcium silicate and hydrated calcium aluminosilicate in cement, significantly improving the early strength of the cement. During cement grinding, alcohol molecules act as surfactants, positively impacting the grinding process. Furthermore, the microparticles used in this invention are uniformly dispersed around the cement particles, increasing the distance between them and preventing further agglomeration. This effectively promotes cement grinding, reduces cement fineness, and increases specific surface area. Maltodextrin is uniformly dispersed and adsorbed around silica microparticles, alumina microparticles, and calcium carbonate microparticles, preventing particle aggregation. Thickener molecules increase solution viscosity, preventing microparticle precipitation and ensuring stable microparticle existence in the solution. A sodium dihydrogen phosphate and disodium hydrogen phosphate buffer solution maintains a stable pH between 6 and 8, preventing precipitation caused by hydrolysis and dissolution of silica, alumina, and calcium carbonate microparticles due to pH changes. The incorporation of this early-strength cement grinding aid results in a 15%-25% increase in early strength (1 day), demonstrating a significant improvement effect.

[0025] The present invention will be further described below with reference to specific embodiments. Detailed Implementation

[0026] To illustrate in detail the advantages of the early-strength cement grinding aid and its preparation method provided in the embodiments of the present invention, specific embodiments are used to describe the present invention below. Furthermore, the implementation of the present invention is described below with reference to specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0027] Example 0

[0028] No grinding aids were added during the cement grinding process to prepare blank cement.

[0029] Example 1

[0030] Dissolve 0.5 parts sodium carboxymethyl cellulose, 10 parts maltodextrin, 1 part sodium dihydrogen phosphate, and 6 parts disodium hydrogen phosphate in 100 parts water and let stand for more than 12 hours to allow the sodium carboxymethyl cellulose to completely dissolve in the water.

[0031] 16 parts of silica microparticles, 8 parts of alumina microparticles, and 32 parts of calcium carbonate microparticles were added to the above aqueous solution, and emulsified at 5000 rpm for 30 minutes using a high-speed shear mill to obtain a homogeneous emulsion. Then, 0.1 parts of sodium polyacrylate, 0.1 parts of sodium dodecanoate, 15 parts of ethylene glycol, and 25 parts of polyethylene glycol were added and stirred until a stable solution was formed to obtain an early-strength cement grinding aid.

[0032] Example 2

[0033] Dissolve 1 part hydroxypropyl methylcellulose, 3 parts maltodextrin, 2 parts sodium dihydrogen phosphate, and 4 parts disodium hydrogen phosphate in 80 parts water and let stand for more than 12 hours to allow the hydroxypropyl methylcellulose to completely dissolve in the water.

[0034] 20 parts of silica microparticles, 10 parts of alumina microparticles, and 30 parts of calcium carbonate microparticles were added to the above aqueous solution and emulsified at 7000 rpm for 30 minutes using a high-speed shear mill to obtain a homogeneous emulsion. Then, 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, 25 parts of polyglycerol, and 25 parts of polyethylene glycol were added and mixed until a stable solution was formed to obtain an early-strength cement grinding aid.

[0035] Example 3

[0036] Dissolve 0.8 parts sodium carboxymethyl cellulose, 2 parts maltodextrin, 3 parts sodium dihydrogen phosphate, and 3 parts disodium hydrogen phosphate in 85 parts water and let stand for more than 12 hours to allow the sodium carboxymethyl cellulose to completely dissolve in the water.

[0037] 22 parts of silica microparticles, 11 parts of alumina microparticles, and 22 parts of calcium carbonate microparticles were added to the above aqueous solution and emulsified at 8000 rpm for 30 minutes using a high-speed shear mill to obtain a homogeneous emulsion. Then, 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, 15 parts of polyethylene glycol, and 25 parts of glycerol were added and stirred until a stable solution was formed to obtain an early-strength cement grinding aid.

[0038] Example 4

[0039] Dissolve 2 parts sodium alginate, 1 part maltodextrin, 4 parts sodium dihydrogen phosphate, and 2 parts disodium hydrogen phosphate in 70 parts water and let stand for more than 12 hours to allow the sodium alginate to completely dissolve in the water.

[0040] 28 parts of silica microparticles, 14 parts of alumina microparticles, and 14 parts of calcium carbonate microparticles were added to the above aqueous solution and emulsified at 12,000 rpm for 30 minutes using a high-speed shear mill to obtain a homogeneous emulsion. Then, 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, 10 parts of ethylene glycol, and 10 parts of glycerol were added and mixed until a stable solution was formed to obtain an early-strength cement grinding aid.

[0041] Example 5

[0042] Dissolve 1.5 parts sodium alginate, 4 parts maltodextrin, 2 parts sodium dihydrogen phosphate, and 5 parts disodium hydrogen phosphate in 80 parts water and let stand for more than 12 hours to allow the sodium alginate to completely dissolve in the water.

[0043] 22 parts of silica microparticles, 11 parts of alumina microparticles, and 22 parts of calcium carbonate microparticles were added to the above aqueous solution and emulsified at 10,000 rpm for 30 minutes using a high-speed shear mill to obtain a homogeneous emulsion. Then, 0.2 parts of polycarboxylate superplasticizer, 0.2 parts of polyacrylamide, 0.1 parts of sodium octadecanoate, 15 parts of ethylene glycol, and 25 parts of polyglycerol were added and stirred until a stable solution was formed, yielding an early-strength cement grinding aid.

[0044] Comparative Example 1

[0045] Dissolve 0.8 parts sodium carboxymethyl cellulose, 5 parts maltodextrin, 3 parts sodium dihydrogen phosphate, and 3 parts disodium hydrogen phosphate in 85 parts water and let stand for more than 12 hours to allow the sodium carboxymethyl cellulose to completely dissolve in the water.

[0046] Add 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, 55 parts of triethanolamine, 15 parts of polyethylene glycol, and 25 parts of glycerol to the above aqueous solution and mix and stir until a stable solution is formed to obtain a comparative early-strength cement grinding aid.

[0047] Comparative Example 2

[0048] Dissolve 0.8 parts sodium carboxymethyl cellulose, 5 parts maltodextrin, 3 parts sodium dihydrogen phosphate, and 3 parts disodium hydrogen phosphate in 85 parts water and let stand for more than 12 hours to allow the sodium carboxymethyl cellulose to completely dissolve in the water.

[0049] Add 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, and 55 parts of hydrated calcium silicate synthesized by precipitation method to the above solution. Emulsify the emulsion using a high-speed shear mill at 8000 rpm for 30 minutes to obtain a homogeneous emulsion. Then add 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, 15 parts of polyethylene glycol, and 25 parts of glycerol and mix until a stable solution is formed to obtain a comparative early-strength cement grinding aid.

[0050] Comparative Example 3

[0051] Dissolve 0.8 parts sodium carboxymethyl cellulose, 5 parts maltodextrin, 3 parts sodium dihydrogen phosphate, and 3 parts disodium hydrogen phosphate in 85 parts water and let stand for more than 12 hours to allow the sodium carboxymethyl cellulose to completely dissolve in the water.

[0052] Add 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, and 55 parts of hydrated calcium aluminosilicate synthesized by precipitation method to the above solution. Emulsify the emulsion using a high-speed shear mill at 8000 rpm for 30 minutes to obtain a homogeneous emulsion. Then add 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, 15 parts of polyethylene glycol, and 25 parts of glycerol and mix until a stable solution is formed to obtain a comparative early-strength cement grinding aid.

[0053] Comparative Example 4

[0054] Dissolve 0.8 parts sodium carboxymethyl cellulose, 5 parts maltodextrin, 3 parts sodium dihydrogen phosphate, and 3 parts disodium hydrogen phosphate in 85 parts water and let stand for more than 12 hours to allow the sodium carboxymethyl cellulose to completely dissolve in the water.

[0055] 22 parts of silica microparticles, 11 parts of alumina microparticles, and 22 parts of calcium carbonate microparticles were added to the above aqueous solution and emulsified at 8000 rpm for 30 minutes using a high-speed shear mill to obtain a homogeneous emulsion. Then, 15 parts of polyethylene glycol and 25 parts of glycerol were added and stirred until a stable solution was formed to obtain a comparative early-strength cement grinding aid.

[0056] Comparative Example 5

[0057] Dissolve 0.8 parts sodium carboxymethyl cellulose, 5 parts maltodextrin, 3 parts sodium dihydrogen phosphate, and 3 parts disodium hydrogen phosphate in 85 parts water and let stand for more than 12 hours to allow the sodium carboxymethyl cellulose to completely dissolve in the water.

[0058] 22 parts of silica powder, 11 parts of alumina powder, and 22 parts of calcium carbonate powder were added to the above aqueous solution and emulsified at 8000 rpm for 30 minutes using a high-speed shear mill to obtain a homogeneous emulsion. Then, 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of sodium octadecanoate, 15 parts of polyethylene glycol, and 25 parts of glycerol were added and stirred until a stable solution was formed to obtain a comparative early-strength cement grinding aid.

[0059] Table 1. Cement preparation methods in Examples 0, 1-5 and Comparative Examples 1-5

[0060]

[0061]

[0062] Table 2. Comparison results of cement grinding performance and strength of blank, examples A1-5, and comparative examples B1-5 are shown below.

[0063]

[0064]

[0065] As can be seen from the data in Table 2, the early-strength cement grinding aids provided in Examples 1-5 not only have good grinding effects but also good early-strength effects, such as a maximum increase of 3.6 MPa in 1-day strength, a maximum increase of 5.9 MPa in 3-day strength, and a maximum increase of 4.8 MPa in 28-day strength. Among them, when the weight ratio of silica microparticles, alumina microparticles, and calcium carbonate microparticles in Examples 1-4 changed from 2:1:4 to 2:1:1, Example 3 showed the best early-strength effect. That is, the optimal early-strength improvement effect was achieved when the mass ratio of silica microparticles, alumina microparticles, and calcium carbonate microparticles was 2:1:2. Compared with Comparative Examples 1-3, which used triethanolamine, hydrated calcium silicate, and hydrated calcium aluminosilicate as early-strength agents, Examples 1-5 of the present invention showed a significant increase in early-strength.

[0066] In Comparative Example 4, no particle structure control agent was used. The crystal structure of hydrated calcium silicate and hydrated calcium aluminosilicate, formed by the dissolution of silica microparticles, alumina microparticles, and calcium carbonate microparticles, was not controlled, failing to form small and dispersed crystal nuclei. This affected the early strength of the cement, resulting in an early strength increase of only 60% of that in Example 4. Comparative Example 5 used silica powder, alumina powder, and calcium carbonate powder with particle sizes in the tens of micrometers range. Because the powders dissolved slowly in the cement, the formation of hydrated calcium silicate and hydrated calcium aluminosilicate crystal nuclei was slow, and the early strength increase was not significant.

[0067] Table 3. Comparison results of standard cement consistency, setting time, and mortar fluidity for blank, examples A1-5, and comparative examples B1-5 are shown below.

[0068]

[0069] As can be seen from the data in Table 3, the early-strength cement grinding aids provided in Examples 1-6 have good compatibility with water-reducing agents, with the standard consistency of cement varying within ±0.2%, the setting time varying within ±10 min, and the mortar fluidity varying within ±10 mm.

[0070] Furthermore, by adjusting the ratio of sodium dihydrogen phosphate to disodium hydrogen phosphate, the pH range of the early-strength cement grinding aid solution of this invention can be ensured to be 6-8. Within this pH range, it is possible to prevent the silica microparticles, alumina microparticles, and calcium carbonate microparticles from denaturing due to excessively low or high pH, ​​thereby further stabilizing the production of the early-strength cement grinding aid.

[0071] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0072] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A grinding aid for early-strength cement, characterized in that, Early-strength cement grinding aid solution is provided in the following parts by weight: 16-28 parts of silica microparticles; 8-14 parts of alumina microparticles; 14-32 parts of calcium carbonate microparticles; 0.2-0.5 parts of particle structure control agent; Thickener 0.5-2 parts; 1-10 parts maltodextrin; 1-4 parts of sodium dihydrogen phosphate; 2-6 parts of disodium hydrogen phosphate; 20-50 parts of alcohols (organic compounds); 70-100 parts water; The particle size range of the silica microparticles is 100-1000 nm, the particle size range of the alumina microparticles is 100-1000 nm, and the particle size range of the calcium carbonate microparticles is 100-1000 nm. The particle structure control agent is a mixture of the first composition and the second composition. The first composition is a mixture of one or any two or three of sodium polyacrylate, polyacrylamide, and polycarboxylic acid superplasticizer polymer. The second composition is one or any two or more of sodium dodecanoate. The pH range of the early-strength cement grinding aid solution is 6-8.

2. The early-strength cement grinding aid as described in claim 1, characterized in that: The thickener is at least one of hydroxypropyl methylcellulose, sodium alginate, sodium carboxymethyl cellulose, or a mixture of any two or three of these.

3. The early-strength cement grinding aid as described in claim 1, characterized in that: The alcoholic organic compound is at least one of ethylene glycol, polyethylene glycol, glycerol, and polyglycerol, or a mixture of any two or three of them, or a mixture of all four.

4. The early-strength cement grinding aid as described in claim 3, characterized in that: When the alcoholic organic compound contains polyethylene glycol, the molecular weight of the polyethylene glycol is in the range of 200-2000; When the alcoholic organic compound contains polyglycerol, the polyglycerol has a molecular weight range of 200-1000.

5. A method for preparing an early-strength cement grinding aid according to any one of claims 1-4, characterized in that, Includes the following steps, by weight: Step 1: Take 0.5-2 parts thickener, 1-10 parts maltodextrin, 1-4 parts sodium dihydrogen phosphate, and 2-6 parts disodium hydrogen phosphate and dissolve them in 70-100 parts water. Soak for at least 12 hours to obtain a soaking solution. Step 2: Take 16-28 parts of silica microparticles, 8-14 parts of alumina microparticles, and 14-32 parts of calcium carbonate microparticles and place them in a mixer to mix evenly. Then add them to the soaking solution in step 1. At the same time, use a high-speed shear machine to emulsify at a speed of 5000-12000 rpm for 30 minutes to obtain a homogeneous emulsion. The third step involves adding 0.2-0.5 parts of particle structure control agent and 20-50 parts of alcohol organic matter to the homogenized emulsion from the second step, and then stirring until a stable solution is formed to obtain an early-strength cement grinding aid solution.

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