Preparation method and application of nano calcium silicate nucleating agent

Abstract

The invention provides a preparation method and application of a nano calcium silicate nucleating agent, and relates to the technical field of nano material preparation, the preparation method comprises the following steps: conveying a calcium salt solution, a silicate solution and a dispersant solution into a microfluidic reactor for reaction to obtain the nano calcium silicate nucleating agent; wherein the retention time of the reaction in a microchannel of the microfluidic reactor is 1 to 10 minutes; and the inner diameter of the microchannel is 20-500 [mu] m. The invention solves the technical problems of slow mass and heat transfer, long reaction time and need of exploration and amplification of the process in the traditional kettle type or magnetic stirring process for preparing nano calcium silicate, and achieves the technical effects of fast mass and heat transfer, high production efficiency, easy industrialization amplification and shortening of the industrialization research and development period. The obtained nano calcium silicate nucleating agent is beneficial to improving the early strength performance of cement, and has no influence on the later strength of the cement.

Description

Technical Field

[0001] The invention relates to the technical field of nano material preparation, in particular to a preparation method of a nano calcium silicate crystal nucleating agent and application thereof. Background Art

[0002] Cement is an indispensable basic material in modern construction, and its performance directly affects the quality, lifespan and safety of buildings. Cement compressive strength is one of the main indicators of cement performance, and compressive strength is often affected by the degree of hydration, the type and microstructure of hydration products, and the porosity.

[0003] In order to improve the compressive strength of cement, various cement early strength agents or enhancers have been widely studied and applied; these early strength agents or enhancers improve the performance of cement by providing additional crystal nuclei, changing the structure of hydration products, improving the dispersibility of cement paste, etc. However, traditional cement early strength agents still have certain limitations in improving early strength and long-term durability.

[0004] At present, nano calcium silicate has great advantages in improving the early strength of cement. However, since nano calcium silicate is mainly synthesized through a kettle stirring process, it takes a long time. It often takes more than several hours from dropwise addition and stirring to obtaining a sample, which greatly affects the production efficiency of this type of nucleating agent and is unable to respond to production needs in a timely manner. At the same time, there is a problem of slow mass transfer in the synthesis process of nano calcium silicate, and the stirring process is affected by fluid mass transfer, shear force, etc. during the scale-up production process. During the scale-up process, due to the jump in Reynolds number, the mixing efficiency of the fluid cannot be simply scaled up in proportion. The resulting differences in fluid dynamics parameters need to be adjusted repeatedly. Therefore, it is necessary to gradually scale up and continuously adjust equipment, process routes and parameters to solve the industrial production process, which extends the R&D cycle and production cost of the project's industrialization process.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the purposes of the present invention is to provide a method for preparing a nano calcium silicate crystal nucleus agent, which can quickly prepare the calcium silicate crystal nucleus agent compared with the traditional kettle type or magnetic stirring process, and effectively improves the production efficiency of the nano calcium silicate crystal nucleus agent.

[0007] The second purpose of the present invention is to provide an application of a nano calcium silicate crystal nucleating agent, which is beneficial to improving the early strength performance of cement while having no effect on the later strength of cement.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, a method for preparing a nano calcium silicate crystal nucleating agent comprises the following steps:

[0010] The calcium salt solution, the silicate solution and the dispersant solution are transported to a microfluidic reactor for reaction to obtain the nano calcium silicate crystal nucleus agent;

[0011] The residence time of the reaction in the microchannel of the microfluidic reactor is 1 min to 10 min;

[0012] The inner diameter of the microchannel is 20 μm to 500 μm;

[0013] The pH of the dispersant solution is 7 to 9;

[0014] The pH of the solution of the nano calcium silicate crystal nucleus agent is 10.5-12.

[0015] Furthermore, the calcium salt solution includes at least one of a calcium chloride aqueous solution, a calcium formate aqueous solution, a calcium nitrate aqueous solution, a calcium oxalate aqueous solution, a calcium hypochlorite aqueous solution and a calcium acetate aqueous solution.

[0016] Furthermore, the mass proportion of calcium salt in the calcium salt solution is 30% to 60%.

[0017] Furthermore, the silicate solution includes at least one of a potassium silicate aqueous solution, a potassium aluminum silicate aqueous solution and a sodium metasilicate aqueous solution.

[0018] Furthermore, the mass percentage of silicate in the silicate solution is 25% to 50%.

[0019] Furthermore, the dispersant solution includes at least one of a polyvinyl pyrrolidone aqueous solution, a polycarboxylic acid polymer aqueous solution, a methyl cellulose aqueous solution and a polyvinyl alcohol aqueous solution.

[0020] Furthermore, the mass proportion of the dispersant in the dispersant solution is 10% to 30%.

[0021] Furthermore, the preparation method comprises the following steps:

[0022] The calcium salt solution, the silicate solution and the dispersant solution are respectively pumped into a microfluidic reactor through pipelines for reaction to obtain the nano calcium silicate crystal nucleating agent;

[0023] Wherein, the mass ratio of the calcium salt solution, the silicate solution and the dispersant solution can be controlled between (0.1-0.3):(0.1-0.3):1.

[0024] Furthermore, taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt solution accounts for 10% to 25%, the flow rate of the silicate solution accounts for 15% to 35%, and the flow rate of the dispersant solution accounts for 25% to 60%.

[0025] In a second aspect, a nano calcium silicate nucleating agent prepared by any of the preparation methods described above is used in cement early strength agent.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The preparation method of the nano calcium silicate crystal nucleus agent provided by the present invention is to prepare the nano calcium silicate material by a microfluidic process. Compared with the preparation of the nano calcium silicate material by a traditional kettle or magnetic stirring process, the advantages are: (1) fast mass and heat transfer. Since the micron-level channel of the microfluidic reactor has an ultra-large specific surface area, the material can respond quickly, effectively improving the process efficiency; (2) short reaction time. Since the microfluidic process regulates the reaction microenvironment, the material can fully react in a very short time, effectively reducing the time required for the reaction; (3) no amplification effect. The microfluidic process does not need to explore the amplification process, and the industrialization process can be realized by increasing the number of microchannels, which greatly shortens the industrialization research and development cycle; (4) the nano calcium silicate crystal nucleus agent prepared by the microfluidic process can improve the early strength performance of cement, and has no effect on the later strength of cement.

[0028] The application of the nano calcium silicate crystal nucleating agent provided by the present invention is beneficial to improving the early strength performance of cement, while having no influence on the later strength of cement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 This is a transmission electron microscope image of nano calcium silicate provided in Example 1 of the present invention;

[0031] Figure 2 This is a state diagram of the nano calcium silicate crystal nucleus agent obtained in the test example of the present invention after being placed for one day;

[0032] Figure 3 This is a state diagram of the nano calcium silicate crystal nucleus agent obtained in the test example of the present invention after being placed for one month. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0034] According to a first aspect of the present invention, a method for preparing a nano calcium silicate crystal nucleating agent is provided, comprising the following steps:

[0035] The calcium salt solution, the silicate solution and the dispersant solution are transported to a microfluidic reactor for reaction to obtain a nano calcium silicate crystal nucleus agent;

[0036] The residence time of the reaction in the microchannel of the microfluidic reactor can be 1 min to 10 min, and its typical but non-limiting residence time is, for example, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min;

[0037] Meanwhile, the inner diameter of the microchannel may be 20 μm to 500 μm, and typical but non-limiting inner diameters thereof are, for example, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 150 μm, 200 μm, 300 μm, 400 μm, and 500 μm;

[0038] It should be noted that the pH of the dispersant solution may be 7-9, and the pH of the solution of the nano calcium silicate crystal nucleating agent may be 10.5-12.

[0039] In the present invention, a microfluidic process is adopted to prepare a synthetic nano calcium silicate crystal nucleus agent, which solves the problems of long reaction time, slow synthesis speed and the need to explore an amplification process in the production of nano calcium silicate by traditional kettle or magnetic stirring processes. By regulating the microenvironment of the synthesis process, the rapid synthesis of the nano calcium silicate crystal nucleus agent is achieved, the synthesis efficiency is greatly improved, and the reaction time is effectively shortened.

[0040] It should be noted that the nano calcium silicate nucleating agent is mainly composed of calcium silicate nanomaterials, water and dispersants; in the nano calcium silicate nucleating agent, calcium silicate serves as the main nucleating agent and organic matter serves as a dispersant, thereby forming a dispersed nano calcium silicate nucleating agent, which can provide more nucleation sites for the cement hydration product hydrated calcium silicate gel, effectively reduce its nucleation barrier, accelerate the degree of cement hydration, and is beneficial to improving the early strength of cement.

[0041] In a preferred embodiment, the calcium salt solution includes but is not limited to at least one of a calcium chloride aqueous solution, a calcium formate aqueous solution, a calcium nitrate aqueous solution, a calcium oxalate aqueous solution, a calcium hypochlorite aqueous solution and a calcium acetate aqueous solution; at the same time, the mass proportion of the calcium salt in the calcium salt solution can be 30% to 60%, and its typical but non-limiting mass proportion is, for example, 30%, 40%, 50%, and 60%.

[0042] In a preferred embodiment, the silicate solution includes but is not limited to at least one of an aqueous potassium silicate solution, an aqueous potassium aluminum silicate solution and an aqueous sodium metasilicate solution; at the same time, the mass proportion of silicate in the silicate solution can be 25% to 50%, and its typical but non-limiting mass proportion is, for example, 25%, 30%, 35%, 40%, 45%, and 50%.

[0043] In the present invention, the dispersant solution includes but is not limited to at least one of a polyvinyl pyrrolidone aqueous solution, a polycarboxylic acid polymer aqueous solution, a methyl cellulose aqueous solution and a polyvinyl alcohol aqueous solution; the mass proportion of the dispersant in the dispersant solution can be 10% to 30%, and its typical but non-limiting mass proportion is, for example, 10%, 15%, 20%, 25%, and 30%.

[0044] In a preferred embodiment, the preparation method of the present invention comprises the following steps:

[0045] The calcium salt solution, the silicate solution and the dispersant solution are respectively pumped into a microfluidic reactor through pipelines for reaction to obtain a nano calcium silicate crystal nucleating agent;

[0046] Wherein, the mass ratio of the calcium salt solution, the silicate solution and the dispersant solution can be controlled between (0.1-0.3):(0.1-0.3):1.

[0047] In a preferred embodiment, based on the total solution delivery flow rate of 100%, the flow rate of the calcium salt solution may account for 10% to 25%, the flow rate of the silicate solution may account for 15% to 35%, and the flow rate of the dispersant solution may account for 25% to 60%.

[0048] In summary, under the coordinated cooperation of various process parameters, the present invention can quickly prepare nano calcium silicate crystal nucleus agent through the microfluidic process. Compared with the traditional kettle or magnetic stirring process, the production efficiency of the nano calcium silicate crystal nucleus agent is effectively improved, the time required for production is significantly reduced, and the industrialization research and development cycle is greatly shortened. At the same time, the obtained nano calcium silicate crystal nucleus agent can be used as a cement early strength agent, which can effectively improve the early strength performance of cement and has no effect on the later strength of cement.

[0049] A typical preparation method of a nano calcium silicate crystal nucleating agent comprises the following steps:

[0050] (1) Preparation of solution:

[0051] A calcium salt aqueous solution is prepared, wherein the calcium salt used is at least one selected from calcium chloride, calcium formate, calcium nitrate, calcium oxalate, calcium hypochlorite and calcium acetate, and the mass proportion of the calcium salt in the calcium salt aqueous solution is 30% to 60%;

[0052] Prepare a silicate aqueous solution, wherein the silicate used is selected from at least one of potassium silicate, potassium aluminum silicate and sodium metasilicate, and the mass proportion of the silicate in the silicate aqueous solution is 25% to 50%;

[0053] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from at least one of polyvinyl pyrrolidone, polycarboxylic acid polymer, methyl cellulose and polyvinyl alcohol, and the mass proportion of the dispersant in the dispersant aqueous solution is 10% to 30%;

[0054] (2) Microfluidic process:

[0055] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is controlled between (0.1-0.3): (0.1-0.3): 1;

[0056] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into a microfluidic reactor through three-way pipes for reaction. Taking the total solution transport flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 10% to 25%, the flow rate of the silicate aqueous solution accounts for 15% to 35%, and the flow rate of the dispersant aqueous solution accounts for 25% to 60%. The residence time of the reaction in the microchannel of the microfluidic reactor is 1 min to 10 min, and the inner diameter of the microchannel is 20 μm to 500 μm, so as to obtain a nano calcium silicate solution, namely a nano calcium silicate crystal nucleating agent.

[0057] Conventional microfluidic processes often use single-channel or two-channel pipelines for sample injection, which makes it impossible to meet the reaction requirements of the samples. However, the microfluidic method in the present invention can use three-channel pipelines for simultaneous sample injection. Through the dynamic regulation of pH and the coordinated optimization of flow rate and tube diameter parameters, the preparation of stable nanocrystal core agents can be effectively achieved.

[0058] According to a second aspect of the present invention, there is provided a use of a nano calcium silicate crystal nucleating agent prepared by any of the preparation methods described above in a cement early strength agent.

[0059] The application of the nano calcium silicate crystal nucleating agent provided by the present invention is beneficial to improving the early strength performance of cement, while having no influence on the later strength of cement.

[0060] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0061] Example 1

[0062] A method for preparing a nano calcium silicate crystal nucleating agent comprises the following steps:

[0063] (1) Preparation of solution:

[0064] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium chloride, and the mass proportion of calcium chloride in the calcium salt aqueous solution is 40%;

[0065] A silicate aqueous solution is prepared, wherein the silicate used is selected from sodium metasilicate, and the mass proportion of sodium metasilicate in the silicate aqueous solution is 50%;

[0066] A dispersant aqueous solution is prepared, wherein the dispersant used is selected from polyvinyl pyrrolidone, the mass proportion of polyvinyl pyrrolidone in the dispersant aqueous solution is 20%, and the pH of the dispersant aqueous solution is adjusted to 7.5;

[0067] (2) Microfluidic process:

[0068] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.2:0.2:1;

[0069] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into a microfluidic reactor through three-way pipes for reaction. Taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 20%, the flow rate of the silicate aqueous solution accounts for 30%, and the flow rate of the dispersant aqueous solution accounts for 50%. The residence time of the reaction in the microchannel of the microfluidic reactor is 2 minutes, and the inner diameter of the microchannel is 50 μm, so as to obtain a milky white nano calcium silicate solution (pH is 10.5-12), which is the nano calcium silicate crystal nucleating agent.

[0070] Figure 1 This is a transmission electron microscope image of the nano-calcium silicate obtained in this example, and the morphology is a two-dimensional lamellar structure.

[0071] Example 2

[0072] A method for preparing a nano calcium silicate crystal nucleating agent comprises the following steps:

[0073] (1) Preparation of solution:

[0074] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium nitrate, and the mass proportion of calcium nitrate in the calcium salt aqueous solution is 50%;

[0075] A silicate aqueous solution is prepared, wherein the silicate used is selected from potassium silicate, and the mass proportion of potassium silicate in the silicate aqueous solution is 40%;

[0076] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from methyl cellulose, the mass proportion of methyl cellulose in the dispersant aqueous solution is 15%, and the pH of the dispersant aqueous solution is adjusted to 8.5;

[0077] (2) Microfluidic process:

[0078] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.2:0.25:1;

[0079] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into a microfluidic reactor through three-way pipes for reaction. Taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 25%, the flow rate of the silicate aqueous solution accounts for 25%, and the flow rate of the dispersant aqueous solution accounts for 50%. The residence time of the reaction in the microchannel of the microfluidic reactor is 6 minutes, and the inner diameter of the microchannel is 100 μm, so as to obtain a milky white nano calcium silicate solution (pH is 10.5-12), which is the nano calcium silicate crystal nucleating agent.

[0080] Example 3

[0081] A method for preparing a nano calcium silicate crystal nucleating agent comprises the following steps:

[0082] (1) Preparation of solution:

[0083] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium formate, and the mass proportion of calcium formate in the calcium salt aqueous solution is 35%;

[0084] A silicate aqueous solution is prepared, wherein the silicate used is selected from sodium metasilicate, and the mass proportion of sodium metasilicate in the silicate aqueous solution is 45%;

[0085] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from a polycarboxylic acid polymer, the mass proportion of the polycarboxylic acid polymer in the dispersant aqueous solution is 15%, and the pH of the dispersant aqueous solution is adjusted to 9;

[0086] (2) Microfluidic process:

[0087] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.25:0.2:1;

[0088] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into a microfluidic reactor through three-way pipes for reaction. Taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 20%, the flow rate of the silicate aqueous solution accounts for 20%, and the flow rate of the dispersant aqueous solution accounts for 60%. The residence time of the reaction in the microchannel of the microfluidic reactor is 3 minutes, and the inner diameter of the microchannel is 150 μm, so as to obtain a milky white nano calcium silicate solution (pH is 10.5-12), which is the nano calcium silicate crystal nucleating agent.

[0089] Example 4

[0090] A method for preparing a nano calcium silicate crystal nucleating agent comprises the following steps:

[0091] (1) Preparation of solution:

[0092] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium hypochlorite, and the mass proportion of calcium hypochlorite in the calcium salt aqueous solution is 50%;

[0093] A silicate aqueous solution is prepared, wherein the silicate used is selected from potassium aluminum silicate, and the mass proportion of potassium aluminum silicate in the silicate aqueous solution is 50%;

[0094] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from polyvinyl alcohol, the mass proportion of polyvinyl alcohol in the dispersant aqueous solution is 20%, and the pH of the dispersant aqueous solution is adjusted to 8;

[0095] (2) Microfluidic process:

[0096] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.25:0.15:1; the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution are pumped into a microfluidic reactor through three-way pipes for reaction. Taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 25%, the flow rate of the silicate aqueous solution accounts for 30%, and the flow rate of the dispersant aqueous solution accounts for 45%. The residence time of the reaction in the microchannel of the microfluidic reactor is 10 minutes, and the inner diameter of the microchannel is 300 μm, thereby obtaining a milky white nano calcium silicate solution (pH of 10.5-12), which is the nano calcium silicate crystal nucleating agent.

[0097] Example 5

[0098] A method for preparing a nano calcium silicate crystal nucleating agent comprises the following steps:

[0099] (1) Preparation of solution:

[0100] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium acetate, and the mass proportion of calcium acetate in the calcium salt aqueous solution is 45%;

[0101] A silicate aqueous solution is prepared, wherein the silicate used is selected from sodium metasilicate, and the mass proportion of sodium metasilicate in the silicate aqueous solution is 40%;

[0102] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from a polycarboxylic acid polymer, the mass proportion of the polycarboxylic acid polymer in the dispersant aqueous solution is 10%, and the pH of the dispersant aqueous solution is adjusted to 7.5;

[0103] (2) Microfluidic process:

[0104] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.2:0.2:1;

[0105] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into a microfluidic reactor through three-way pipes for reaction. Taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 20%, the flow rate of the silicate aqueous solution accounts for 25%, and the flow rate of the dispersant aqueous solution accounts for 55%. The residence time of the reaction in the microchannel of the microfluidic reactor is 8 minutes, and the inner diameter of the microchannel is 400 μm, so as to obtain a milky white nano calcium silicate solution (pH is 10.5-12), which is the nano calcium silicate crystal nucleating agent.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that in this comparative example, no calcium salt aqueous solution, silicate aqueous solution and dispersant aqueous solution are prepared, but only water is delivered to the microfluidic reactor;

[0108] The rest are the same as in Example 1.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 2 is that the residence time of the reaction in the microchannel of the microfluidic reactor in this comparative example is 10 s;

[0111] The rest are the same as in Example 1.

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 2 is that in this comparative example, the residence time of the reaction in the microchannel of the microfluidic reactor is 2 min, and the inner diameter of the microchannel is 1000 μm;

[0114] The rest are the same as in Example 1.

[0115] Comparative Example 4

[0116] This comparative example adopts the traditional stirring process to prepare the nano calcium silicate crystal nucleating agent, and the corresponding ratio is the same as that in Example 1. The specific operation is to drop the calcium salt solution and the silicate solution into the dispersant aqueous solution at the same time within 15 minutes, the stirring rate is 800 rpm, and the stirring time is 12 hours to obtain the nano crystal nucleating agent product.

[0117] Test example

[0118] The products obtained from Examples 1-5 and Comparative Examples 1-4 were used as cement early strength agents in cement to carry out mortar strength tests of P·II type cement, which were respectively recorded as Test Group 1, Test Group 2, Test Group 3, Test Group 4, Test Group 5, Comparative Group 1, Comparative Group 2, Comparative Group 3 and Comparative Group 4, thereby obtaining the cement strengths of different types of cement at different ages, as shown in Table 1.

[0119] Table 1

[0120] Experimental Group 1 Experimental Group 2 Experimental Group 3 Experimental Group 4 Experimental Group 5 Comparison group 1 Comparison group 2 Comparison group 3 Comparison group 4 12h / MPa 9.8 10.1 10.9 10.0 10.6 5.4 8.6 9.0 8.3 3d / MPa 43.2 44.2 45.3 43.0 43.9 33.1 41.4 41.2 40.8 28d / MPa 65.4 64.4 64.8 65.0 64.2 60.3 63.5 63.9 63.3

[0121] As can be seen from Table 1, the nano calcium silicate nucleus agent obtained in Examples 1-5 of the present invention is introduced into cement as a cement early strength agent (test groups 1-5), which can effectively improve the early strength of cement (12h), and the improvement effect is significantly better than that of Comparative Examples 1-4. At the same time, it also has a corresponding improvement effect on the compressive strength of 3d and 28d, and does not show the problem of strength shrinkage.

[0122] The actual pictures of the nanocrystalline nucleating agent samples obtained in Example 1 and Comparative Example 4 are shown in Figure 2 and Figure 3 , Figure 2 This is the state after one day of storage. Figure 3 The left picture shows the state after being placed for one month. The left picture shows the nanocrystal nucleus agent sample obtained in Example 1, and the right picture shows the nanocrystal nucleus agent sample obtained in Comparative Example 4. It can be seen that the sample prepared by the stirring process in Comparative Example 4 has poor dispersibility and is prone to precipitation, while the sample prepared by the microfluidic control in Example 1 still has no obvious precipitation after being placed for one month, which shows that it has excellent stability and is more suitable for practical applications.

[0123] In summary, the present invention utilizes the microfluidic process to not only quickly prepare nano calcium silicate crystal nucleating agent, effectively improve the production efficiency of the nano calcium silicate crystal nucleating agent and the stability of the crystal nucleating agent, but also the obtained nano calcium silicate crystal nucleating agent is used in cement as a cement early strength agent, which can effectively improve the early strength of cement, and at the same time, there is no shrinkage problem in the later strength.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a nano calcium silicate crystal nucleating agent, characterized in that: The following steps are involved: The calcium salt solution, the silicate solution and the dispersant solution are transported to a microfluidic reactor for reaction to obtain the nano calcium silicate crystal nucleus agent; The residence time of the reaction in the microchannel of the microfluidic reactor is 1 min to 10 min; The inner diameter of the microchannel is 20 μm to 500 μm; The pH of the dispersant solution is 7 to 9; The pH of the solution of the nano calcium silicate crystal nucleus agent is 10.5-12.

2. The preparation method according to claim 1, characterized in that: The calcium salt solution includes at least one of a calcium chloride aqueous solution, a calcium formate aqueous solution, a calcium nitrate aqueous solution, a calcium oxalate aqueous solution, a calcium hypochlorite aqueous solution and a calcium acetate aqueous solution.

3. The preparation method according to claim 2, characterized in that: The mass proportion of calcium salt in the calcium salt solution is 30% to 60%.

4. The preparation method according to claim 1, characterized in that: The silicate solution includes at least one of a potassium silicate aqueous solution, a potassium aluminum silicate aqueous solution, and a sodium metasilicate aqueous solution.

5. The preparation method according to claim 4, characterized in that: The mass percentage of silicate in the silicate solution is 25% to 50%.

6. The preparation method according to claim 1, characterized in that: The dispersant solution includes at least one of a polyvinyl pyrrolidone aqueous solution, a polycarboxylic acid polymer aqueous solution, a methyl cellulose aqueous solution, and a polyvinyl alcohol aqueous solution.

7. The preparation method according to claim 6, characterized in that: The mass proportion of the dispersant in the dispersant solution is 10% to 30%.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The calcium salt solution, the silicate solution and the dispersant solution are respectively pumped into a microfluidic reactor through pipelines for reaction to obtain the nano calcium silicate crystal nucleating agent; Wherein, the mass ratio of the calcium salt solution, the silicate solution and the dispersant solution can be controlled between (0.1-0.3):(0.1-0.3):

1.

9. The preparation method according to claim 8, characterized in that: Taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt solution accounts for 10% to 25%, the flow rate of the silicate solution accounts for 15% to 35%, and the flow rate of the dispersant solution accounts for 25% to 60%.

10. Use of the nano calcium silicate crystal nucleating agent prepared by the preparation method according to any one of claims 1 to 9 in cement early strength agent.

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