A kind of thermally induced accelerating coagulation microcapsule for cement-based materials and preparation method thereof

Abstract

The present invention discloses a thermally accelerated coagulation microcapsule for cement-based materials and a preparation method thereof. The preparation method of the thermally accelerated coagulation microcapsule comprises the following steps: 1) placing paraffin wax solid and solvent A in a certain volume ratio in a container, then heating at a certain temperature to melt the paraffin wax into a liquid state, wherein solvent A is a polar organic compound that is immiscible with the paraffin wax, is odorless and non-volatile, and has a boiling point much higher than the melting point of the paraffin wax; 2) adding a coagulant to the melted liquid paraffin, stirring the mixture evenly, cooling the mixture in an ice-water mixture, and then filtering the mixture to obtain the thermally accelerated coagulation microcapsules for cement-based materials. The thermally accelerated coagulation microcapsules obtained by the present invention have a particle size of 60 to 150 μm. When used in cement-based materials, they can both ensure the early fluidity of the cement-based cementitious material and accurately control its coagulation time.

Description

Technical Field

[0001] The invention relates to the technical field of building material admixtures, and in particular to a thermally accelerated coagulation microcapsule for cement-based materials and a preparation method thereof. Background Art

[0002] Due to the differences in their components, the setting times of several commonly used cement-based binders after hydration vary significantly. Furthermore, with the increasing demand for cement in the construction industry, some applications require rapid setting, while others prefer natural setting. Accelerators are additives that accelerate the setting and hardening of concrete. They are added at a rate of 1-2% of the cement content. The main types of accelerators are inorganic salts and organic compounds. Inorganic salts are commonly used in my country. Inorganic salt accelerators can be broadly divided into three categories based on their primary components: 1. Accelerators based on sodium and calcium salts; 2. Accelerators based on aluminum salts; and 3. Accelerators based on silicates and sulfates. Directly adding accelerators to cement-based materials can cause the cement-based binder to solidify during construction, losing its fluidity, hindering the construction process and even compromising its performance. Summary of the Invention

[0003] In view of this, the present invention aims to provide a method for preparing thermally induced accelerating coagulation microcapsules for cement-based materials. The obtained thermally induced accelerating coagulation microcapsules for cement-based materials can not only ensure the early fluidity of cement-based cementitious materials, but also accurately control their coagulation time, effectively solving the problem that the existing coagulant is directly added to cement-based cementitious materials, causing the cement-based cementitious materials to lose their state quickly and become unsuitable for construction.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A method for preparing thermally accelerated coagulation microcapsules for cement-based materials comprises the following steps:

[0006] 1) placing paraffin wax solid and solvent A in a certain volume ratio in a container, and then heating at a certain temperature to melt the paraffin wax into a liquid state, wherein solvent A is a polar organic compound that is immiscible with the paraffin wax, is odorless and non-volatile, and has a boiling point much higher than the melting point of the paraffin wax;

[0007] 2) Adding a coagulant to the melted liquid paraffin, stirring evenly, placing the mixture in an ice-water mixture to cool, and then filtering to obtain thermally accelerated coagulant microcapsules for cement-based materials.

[0008] Optionally, in step 1), the volume ratio of the paraffin solid to the solvent A is 1:2-3.

[0009] Optionally, the heating temperature in step 1) is 80-100° C. At the above heating temperature, the paraffin wax can be kept in a completely molten state while the solvent A can be prevented from boiling and volatilizing.

[0010] Optionally, the solvent A in step 1) is one or more of ethylene glycol, propylene glycol, glycerol, butylene glycol, ethyl acetate, methyl silicone oil, white mineral oil, dimethyl sulfoxide and diphenyl ether.

[0011] Optionally, the stirring rate in step 2) is 250-400 r / min, and the stirring time is 1-3 h. Under the above stirring conditions, the paraffin wax and the coagulant can be completely dispersed in the solvent A.

[0012] Optionally, the coagulant C in step 2) is one or more of potassium sulfate, sodium sulfate, aluminum sulfate, sodium chloride, potassium chloride, sodium silicate, potassium silicate, and aluminum silicate, all of which are nanoscale powders.

[0013] Optionally, in step 2), the volume ratio of the coagulant C to the paraffin solid is 1:1-2.

[0014] Optionally, the particle size of the thermally accelerated coagulation microcapsules for cement-based materials is 60 to 150 μm.

[0015] The second object of the present invention is to provide a thermally accelerated coagulation microcapsule for cement-based materials, wherein the thermally accelerated coagulation microcapsule is prepared by the above-mentioned preparation method of the thermally accelerated coagulation microcapsule for cement-based materials.

[0016] Compared with the prior art, the method for preparing thermally accelerated coagulation microcapsules for cement-based materials of the present invention has the following advantages:

[0017] 1. The heat-induced accelerating coagulant microcapsules obtained by the present invention are added as an admixture to cement-based cementitious materials. At room temperature, the outer wall of the capsule will not melt and the coagulant will not be released, thereby ensuring the early fluidity of the cement-based cementitious materials. After a certain period of time, the cement slurry is heated, the capsule melts, the coagulant is released, and the cementitious materials quickly solidify, thereby achieving the purpose of accurately controlling the setting time of the cement-based cementitious materials and making them adaptable to various complex application environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 This is a specific process flow chart for preparing the thermally accelerated coagulation microcapsules of cement-based materials of the present invention;

[0020] Figure 2This is a schematic diagram of the specific preparation structure of the thermally accelerated coagulation microcapsules of cement-based materials of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions and technical effects of the present invention, several embodiments are provided below. Obviously, what is described below is only an embodiment and does not limit the scope of protection of the present invention.

[0022] Example 1

[0023] A method for preparing thermally accelerated coagulation microcapsules for cement-based materials, such as Figure 1 and Figure 2 As shown, the specific steps include:

[0024] 1) placing solid paraffin wax and ethylene glycol (solvent A) in a volume ratio of 1:2 in a beaker, and then heating the paraffin wax on a heated magnetic stirrer until the paraffin wax is completely melted into a liquid state, wherein the heating temperature is controlled at 80° C.;

[0025] 2) adding nano sodium sulfate and nano potassium sulfate (coagulant) to the melted liquid paraffin, wherein the volume ratio of the added coagulant to the paraffin solid is 1:1, and the volume ratio of each component in the coagulant is the same, turning on the magnetic stirrer, and maintaining the above-mentioned heating temperature unchanged, stirring at a stirring rate of 250 r / min for 1 hour, and after stirring it evenly, pouring it evenly onto a glass plate and spreading it, cooling the bottom of the glass plate with an ice-water mixture, and filtering it after it is completely cooled to obtain thermally induced coagulant microcapsules for cement-based materials.

[0026] The microscopic morphology of the thermally accelerated coagulation microcapsules for cement-based materials of this embodiment was observed using an optical microscope, and the particle size of the microcapsules was measured to be 120-150 μm.

[0027] Cement-based cementitious material was prepared by using P·O42.5 grade ordinary Portland cement as cementitious material, adopting a water-binder ratio of 0.45 and adding 0.3% of the mass of the cementitious material of polycarboxylic acid high-efficiency water reducer and stirring.

[0028] The thermally accelerated coagulation microcapsules prepared in this embodiment were added to the above-mentioned cement-based cementitious material, wherein the addition amount of the thermally accelerated coagulation microcapsules in this embodiment is 1% of the mass of the above-mentioned cementitious material, and the setting time and 7d compressive strength were tested. The test results are shown in Table 1. Comparative Example 1 in Table 1 is a cement-based cementitious material without the addition of a coagulant; Comparative Example 2 is a cement-based cementitious material with the addition of a coagulant that has not been treated by the present invention, that is, 1% of the nano-sodium sulfate and nano-potassium sulfate (coagulant) of step 2) is directly added to the above-mentioned cement-based cementitious material; Example 1a is a cement-based cementitious material with the addition of the thermally accelerated coagulant microcapsules of this embodiment, and Example 1b is a cement-based cementitious material with the addition of the thermally accelerated coagulant microcapsules of this embodiment and heated at 60°C.

[0029] As shown in Table 1, the setting time of the cement-based cementitious material containing the microcapsules of this embodiment is significantly longer than that of the cement-based cementitious material directly containing a coagulant, and is comparable to that of the cement-based cementitious material without a coagulant. When the cement-based cementitious material containing the microcapsules of this embodiment is heated, the setting time is shortened, comparable to that of the cement-based cementitious material containing only a coagulant. Furthermore, the 7-day strength of the test blocks also increases after heating, likely due to the melted paraffin filling the pores in the cement, resulting in this increased strength. This indicates that the addition of the microcapsules of this embodiment can maintain the original working state of the cement-based cementitious material, and when heated, it can exert a coagulant-promoting effect comparable to that of the coagulant.

[0030] Table 1

[0031] serial number admixtures Setting time Compressive strength (7d) Comparative Example 1 none 44min 26.3MPa Comparative Example 2 coagulant 10min 25.7MPa Example 1a microcapsules 44min 26.7MPa Example 1b Microcapsules (heating) 13min 31.5MPa

[0032] Example 2

[0033] A method for preparing thermally accelerated coagulation microcapsules for cement-based materials, comprising the following steps:

[0034] 1) placing solid paraffin wax and ethylene glycol (solvent A) in a volume ratio of 1:2 in a beaker, and then heating the paraffin wax on a heated magnetic stirrer until the paraffin wax is completely melted into a liquid state, wherein the heating temperature is controlled at 80° C.;

[0035] 2) adding nano sodium sulfate, nano potassium sulfate, and nano sodium silicate (coagulant) to the melted liquid paraffin, wherein the volume ratio of the added coagulant to the paraffin solid is 1:1, and the volume ratio of each component in the coagulant is the same, turning on a magnetic stirrer, and maintaining the above-mentioned heating temperature unchanged, stirring continuously at a stirring rate of 300 r / min for 1 hour, stirring it evenly, and then pouring it evenly onto a glass plate and spreading it out. The bottom of the glass plate is cooled with an ice-water mixture, and after being completely cooled, filtering is performed to obtain thermally induced coagulant microcapsules for cement-based materials.

[0036] The microscopic morphology of the thermally accelerated coagulation microcapsules for cement-based materials of this embodiment was observed using an optical microscope, and the particle size of the microcapsules was measured to be 120-140 μm.

[0037] The performance of the thermally induced coagulant microcapsules of this embodiment was tested using the method of Example 1. The test results are shown in Table 2.

[0038] As can be seen from Table 2, the thermally induced coagulation microcapsules of this embodiment and the thermally induced coagulation microcapsules of Example 1 exhibit basically the same behavior.

[0039] Table 2

[0040] serial number admixtures Setting time Compressive strength (7d) Comparative Example 1 none 44min 26.3MPa Comparative Example 2 coagulant 9min 26.7MPa Example 2a microcapsules 44min 25.7MPa Example 2b Microcapsules (heating) 13min 30.8MPa

[0041] Example 3

[0042] A method for preparing thermally accelerated coagulation microcapsules for cement-based materials, comprising the following steps:

[0043] 1) placing solid paraffin wax and ethylene glycol (solvent A) in a volume ratio of 1:2 in a beaker, and then heating the paraffin wax on a heated magnetic stirrer until the paraffin wax is completely melted into a liquid state, wherein the heating temperature is controlled at 85° C.;

[0044] 2) adding nano-aluminum sulfate, nano-sodium silicate, and nano-sodium chloride (coagulant) to the melted liquid paraffin, wherein the volume ratio of the added coagulant to the paraffin solid is 1:1.5, and the volume ratio of each component in the coagulant is the same, turning on a magnetic stirrer, and maintaining the above-mentioned heating temperature unchanged, stirring continuously at a stirring rate of 300 r / min for 1 hour, stirring it evenly, and then pouring it evenly onto a glass plate and spreading it out. The bottom of the glass plate is cooled with an ice-water mixture, and after being completely cooled, filtering is performed to obtain thermally induced coagulant microcapsules for cement-based materials.

[0045] The microscopic morphology of the thermally accelerated coagulation microcapsules for cement-based materials of this embodiment was observed using an optical microscope, and the particle size of the microcapsules was measured to be 110-140 μm.

[0046] The performance of the thermally induced coagulant microcapsules of this embodiment was tested using the method of Example 1. The test results are shown in Table 3.

[0047] It can be seen from Table 3 that the heat-induced coagulation-promoting microcapsules of this embodiment and the heat-induced coagulation-promoting microcapsules of Example 1 exhibit basically the same behavior.

[0048] Table 3

[0049] serial number admixtures Setting time Compressive strength (7d) Comparative Example 1 none 44min 26.3MPa Comparative Example 2 coagulant 9min 25.1MPa Example 3a microcapsules 44min 25.4MPa Example 3b Microcapsules (heating) 12min 31.4MPa

[0050] Example 4

[0051] A method for preparing thermally accelerated coagulation microcapsules for cement-based materials, comprising the following steps:

[0052] 1) placing solid paraffin wax and butanediol (solvent A) in a volume ratio of 1:3 in a beaker, and then heating on a heated magnetic stirrer until the paraffin wax is completely melted into a liquid state, wherein the heating temperature is controlled at 90° C.;

[0053] 2) adding nano aluminum sulfate, nano sodium silicate, nano aluminum silicate, and nano sodium chloride (coagulant) to the melted liquid paraffin, wherein the volume ratio of the added coagulant to the paraffin solid is 1:1.5, and the volume ratio of each component in the coagulant is the same, turning on a magnetic stirrer, and maintaining the above-mentioned heating temperature unchanged, stirring at a stirring rate of 350 r / min for 1.5 hours, stirring it evenly, and then pouring it evenly onto a glass plate and spreading it out. The bottom of the glass plate is cooled with an ice-water mixture, and after being completely cooled, filtering it to obtain thermally induced coagulant microcapsules for cement-based materials.

[0054] The microscopic morphology of the thermally accelerated coagulation microcapsules for cement-based materials of this embodiment was observed using an optical microscope, and the particle size of the microcapsules was measured to be 100-140 μm.

[0055] The performance of the thermally induced coagulant-accelerating microcapsules of this embodiment was tested using the method of Example 1, and the test results are shown in Table 4. In this embodiment, the amount of coagulant and microcapsules added was 2%.

[0056] As can be seen from Table 4, the thermally induced coagulation microcapsules of this embodiment and the thermally induced coagulation microcapsules of Example 1 exhibit basically the same behavior.

[0057] Table 4

[0058] serial number admixtures Setting time Compressive strength (7d) Comparative Example 1 none 44min 26.3MPa Comparative Example 2 coagulant 6min 26.1MPa Example 4a microcapsules 44min 26.5MPa Example 4b Microcapsules (heating) 9min 31.8MPa

[0059] Example 5

[0060] A method for preparing thermally accelerated coagulation microcapsules for cement-based materials, comprising the following steps:

[0061] 1) placing solid paraffin wax and butanediol (solvent A) in a volume ratio of 1:3 in a beaker, and then heating on a heated magnetic stirrer until the paraffin wax is completely melted into a liquid state, wherein the heating temperature is controlled at 90° C.;

[0062] 2) adding nano-aluminum sulfate, nano-aluminum silicate, nano-sodium chloride, and nano-potassium chloride (coagulant) to the melted liquid paraffin, wherein the volume ratio of the added coagulant to the paraffin solid is 1:1.5, and the volume ratio of each component in the coagulant is the same, turning on a magnetic stirrer, and maintaining the above-mentioned heating temperature unchanged, stirring continuously at a stirring rate of 400 r / min for 2.5 hours to stir uniformly, then pouring it evenly onto a glass plate and spreading it out, cooling the bottom of the glass plate with an ice-water mixture, and filtering it after it is completely cooled to obtain thermally induced coagulant microcapsules for cement-based materials.

[0063] The microscopic morphology of the thermally accelerated coagulation microcapsules for cement-based materials of this embodiment was observed using an optical microscope, and the particle size of the microcapsules was measured to be 90-110 μm.

[0064] The performance of the thermally induced coagulant microcapsules of this embodiment was tested using the method of Example 1. The test results are shown in Table 5.

[0065] It can be seen from Table 5 that the heat-induced coagulation microcapsules of this embodiment and the heat-induced coagulation microcapsules of Example 1 exhibit basically the same behavior.

[0066] Table 5

[0067] serial number admixtures Setting time Compressive strength (7d) Comparative Example 1 none 44min 26.3MPa Comparative Example 2 coagulant 5min 25.9MPa Example 5a microcapsules 44min 25.8MPa Example 5b Microcapsules (heating) 8min 31.9MPa

[0068] Example 6

[0069] A method for preparing thermally accelerated coagulation microcapsules for cement-based materials, comprising the following steps:

[0070] 1) placing solid paraffin wax and butanediol (solvent A) in a volume ratio of 1:3 in a beaker, and then heating the paraffin wax on a heated magnetic stirrer until the paraffin wax is completely melted into a liquid state, wherein the heating temperature is controlled at 100° C.;

[0071] 2) adding potassium sulfate, sodium sulfate, aluminum sulfate, sodium chloride, potassium chloride, sodium silicate, potassium silicate, and aluminum silicate (coagulant) to the melted liquid paraffin, wherein the volume ratio of the added coagulant to the paraffin solid is 1:2, and the volume ratio of each component in the coagulant is the same, turning on the magnetic stirrer, and maintaining the above-mentioned heating temperature unchanged, stirring continuously at a stirring rate of 400 r / min for 3 hours, and after stirring it evenly, pouring it evenly onto a glass plate and spreading it, cooling the bottom of the glass plate with an ice-water mixture, and filtering it after it is completely cooled to obtain thermally induced coagulant microcapsules for cement-based materials.

[0072] The microscopic morphology of the thermally accelerated coagulation microcapsules for cement-based materials of this embodiment was observed using an optical microscope, and the particle size of the microcapsules was measured to be 70-100 μm.

[0073] The performance of the thermally induced coagulant microcapsules of this embodiment was tested using the method of Example 1. The test results are shown in Table 6.

[0074] It can be seen from Table 6 that the heat-induced coagulation-promoting microcapsules of this embodiment and the heat-induced coagulation-promoting microcapsules of Example 1 exhibit basically the same behavior.

[0075] Table 6

[0076] serial number admixtures Setting time Compressive strength (7d) Comparative Example 1 none 44min 26.3MPa Comparative Example 2 coagulant 5min 26.1MPa Example 6a microcapsules 44min 25.8MPa Example 6b Microcapsules (heating) 8min 31.2MPa

[0077] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing thermally accelerated coagulation microcapsules for cement-based materials, characterized in that: The following steps are involved: 1) Paraffin wax solid and solvent A are placed in a container at a certain volume ratio, and then heated at a certain temperature to melt the paraffin into a liquid state, wherein solvent A is a polar organic compound that is immiscible with the paraffin, is odorless and non-volatile, and has a boiling point much higher than the melting point of the paraffin; 2) Adding a coagulant to the melted liquid paraffin, stirring evenly, cooling in an ice-water mixture, and then filtering to obtain thermally induced coagulant microcapsules for cement-based materials; In step 1), the volume ratio of the paraffin solid to the solvent A is 1:2 to 3; The solvent A in step 1) is one or more of ethylene glycol, propylene glycol, glycerol, butylene glycol, methyl silicone oil, white mineral oil, dimethyl sulfoxide and diphenyl ether; In step 2), the volume ratio of the coagulant to the paraffin wax solid is 1:1 to 2; The particle size of the thermally accelerated coagulation microcapsules for cement-based materials is 60 to 150 μm.

2. The method for preparing thermally accelerated coagulation microcapsules for cement-based materials according to claim 1, characterized in that: The heating temperature in step 1) is 80-100°C.

3. The method for preparing thermally accelerated coagulation microcapsules for cement-based materials according to claim 1, characterized in that: The stirring rate of the stirring in step 2) is 250 to 400 r / min, and the stirring time is 1 to 3 hours.

4. The method for preparing thermally accelerated coagulation microcapsules for cement-based materials according to claim 1, characterized in that: The coagulant in step 2) is one or more of potassium sulfate, sodium sulfate, aluminum sulfate, sodium chloride, potassium chloride, sodium silicate, potassium silicate, and aluminum silicate.

5. A thermally accelerated coagulation microcapsule for cement-based materials, characterized in that: The microcapsules are prepared by the method for preparing thermally accelerated coagulation microcapsules for cement-based materials according to any one of claims 1 to 4.

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