Method for preparing thermally-induced rapid-hardening capsule by dry method

Abstract

The invention discloses a method for preparing a thermally-induced rapid-hardening capsule by a dry method. The method for preparing the thermally-induced rapid-hardening capsule by the dry method comprises the following steps: putting a cementing material accelerator into a particle vibration device, preheating while vibrating, after preheating, adding coating material powder, heating while vibrating, coating the surface of the cementing material accelerator with the coating material powder, stopping heating, and cooling to obtain the thermally-induced rapid-hardening capsule. And adding a lubricant, and continuously stirring by using a stirrer until the temperature of the mixed particles in the particle vibration device is reduced to room temperature, thereby obtaining the thermally-induced rapid-hardening capsule. According to the invention, dry preparation of the thermally-induced quick-setting capsule can be realized, the preparation process is simple and environment-friendly, the obtained thermally-induced quick-setting capsule can enable the initial setting time of a cementing material to be as long as 2 hours at normal temperature, the fluidity of concrete is maintained, pumping and conveying are facilitated, and the conveying cost is reduced; and after heating and excitation, the cementing material can be condensed within 10 minutes, so that rapid molding and demolding of the concrete are facilitated, and the construction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of controllable setting and hydration of cementitious materials, and particularly to a method for dry-preparing heat-induced rapid-setting capsules. Background Art

[0002] "On-demand setting" requires that concrete can maintain a long-term retarding state and good fluidity before setting for easy transportation to reduce transportation costs. When there is a need for molding, the concrete can quickly change from a fluid state to a solid state for easy and rapid demolding to improve construction efficiency. However, the setting and hydration of cementitious materials in concrete is a spontaneous process and is difficult to actively regulate, resulting in the transportation time and construction time of concrete being limited by the hydration and setting time of cementitious materials. Using admixtures such as accelerators and retarders is a common way to regulate the setting and hydration behavior of cementitious materials. Such admixtures can regulate the setting and hydration behavior of cementitious materials, but their functions are relatively single. The dosage of the admixture needs to be accurately controlled according to construction requirements, and it is still impossible to actively regulate the setting and hydration of concrete through external stimuli as required.

[0003] In response to the above problems, some scholars have carried out the preparation of heat-induced rapid-setting capsules. However, the existing preparation of heat-induced rapid-setting capsules often uses chemical synthesis methods. In addition to capsule synthesis during preparation, other experimental steps such as washing and drying are also required. The preparation steps are numerous, the preparation process is relatively cumbersome, the yield of the prepared capsules is low, and there are huge challenges in large-scale production. At the same time, most of the preparation processes often involve liquid reagents, which are prone to generate waste. Moreover, in order to ensure the integrity of the capsule coating and slow down the leakage of the core material, the dosage of the coating material is relatively large, making it difficult for the density of the prepared heat-induced rapid-setting agent capsules to match the density of cementitious materials or concrete, and it is difficult to be uniformly dispersed in cementitious materials or concrete for a long time. In addition, after the cementitious material and the accelerator are mixed, the setting and hardening are fast, and the operation time is usually no more than 5 minutes, the operation window is short, and the construction convenience is poor. Therefore, there is an urgent need to develop a new preparation method for heat-induced rapid-setting capsules. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method for dry-preparing heat-induced rapid-setting capsules to solve the problems of complex preparation process of existing heat-induced rapid-setting capsules, mismatch between the density of the obtained heat-induced rapid-setting capsules and the density of cement concrete, and short operation time window.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows:

[0006] A method for dry-preparing heat-induced rapid-setting capsules, comprising the following steps:

[0007] Place the gelling material accelerator in a particle vibration device and preheat it while vibrating. After the preheating is completed, add the coating material powder and heat it while vibrating to wrap the coating material powder on the surface of the gelling material accelerator. Then, stop heating, add a lubricant, and continuously stir with a stirrer until the temperature of the mixed particles in the particle vibration device drops to room temperature to obtain a thermally induced quick-setting capsule.

[0008] Optionally, by weight, the amounts of each raw material are as follows: the gelling material accelerator: 100 parts, the coating material powder: 1 - 100 parts, and the lubricant: 0.01 - 50 parts.

[0009] Optionally, the gelling material accelerator is one or more of an alkaline accelerator, a sulfate accelerator, and an aluminate accelerator, and the gelling material accelerator is in the form of solid particles with a particle size of 0.00001 - 20 mm.

[0010] Optionally, the alkaline accelerator is one or more of calcium oxide, sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, and calcium hydroxide; the sulfate accelerator is one or more of aluminum sulfate, sodium sulfate, and potassium sulfate; and the aluminate accelerator is one or more of sodium aluminate, potassium aluminate, and calcium aluminate.

[0011] Optionally, the coating material powder is one or more of paraffin powder, polycaprolactone powder, polyethylene powder, polylactic acid powder, polyvinyl alcohol powder, polyethylene glycol powder, stearic acid powder, and agar powder; and the particle size of the coating material powder is 0.000001 - 2 mm.

[0012] Optionally, the lubricant is one or more of graphite powder, talc powder, molybdenum disulfide powder, boron nitride powder, and polytetrafluoroethylene powder.

[0013] Optionally, the particle vibration device is one of a ball mill, a particle polisher, and a cylindrical mixer; the stirrer is one of a paddle stirrer, an anchor stirrer, and a frame stirrer, and the stirring rate is 0.1 - 100 rpm.

[0014] Optionally, the vibration frequency during vibration and preheating is 0.1 - 100000 Hz, the vibration power is 20 - 500 W; the preheating temperature is 40 - 160 °C, and the preheating time is 1 - 30 min.

[0015] Optionally, the addition rate of the coating material powder is 0.001 - 1000 g / min.

[0016] Optionally, the vibration frequency during vibration and heating is 0.1 - 100000 Hz, the vibration power is 20 - 500 W; the heating temperature is 40 - 160 °C, and the heating time is 1 - 120 min.

[0017] Compared with the prior art, the method for dry-preparing heat-induced rapid-setting capsules of the present invention has the following advantages:

[0018] 1. In the present invention, through external heating and vibration, the particles rub and collide with each other. The coating material powder first adheres to the surface of the gelling material rapid-setting agent particles, then melts on the surface of the gelling material rapid-setting agent particles, and separates during the vibration process, and then cools to form a shell layer wrapping the gelling material rapid-setting agent particles, effectively realizing the dry preparation of heat-induced rapid-setting capsules. The whole preparation process is simple, easy to operate and control, with high production efficiency, so it is easy to scale up production. Moreover, the whole preparation process does not involve liquid reagents and no waste is generated, which has very important environmental protection significance.

[0019] 2. After the heat-induced rapid-setting capsules prepared by the method of the present invention are mixed with the gelling material or concrete, the initial setting time of the gelling material can be as long as 2 h at normal temperature, maintaining the fluidity of the concrete, facilitating pumping and transportation, and reducing the transportation cost of the concrete. When there is a need for setting, the wrapped gelling material rapid-setting agent can be released under the action of heat stimulation, realizing the rapid setting and hardening of the gelling material or concrete, facilitating the rapid shaping and demoulding of the concrete, and improving the construction efficiency.

[0020] 3. The method of the present invention is easy to operate. On the premise of maintaining the integrity of the coating of the heat-induced rapid-setting capsules, the density of the heat-induced rapid-setting agent can be conveniently adjusted by adjusting the amount of the coating material powder, so as to match the density of different types of gelling materials or concrete with different fluidities, and realize the uniform distribution of the heat-induced rapid-setting agent in the gelling material or concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 is a schematic flow chart of the preparation of heat-induced rapid-setting capsules by the dry method of the present invention;

[0023] Figure 2 is a schematic structural diagram of the heat-induced rapid-setting capsules prepared by the present invention;

[0024] Figure 3 is a physical diagram of the gelling material rapid-setting agent of the present invention;

[0025] Figure 4 is a physical diagram of the heat-induced rapid-setting capsules of the present invention.

[0026] Reference numerals:

[0027] 1 - Infrared heating lamp, 2 - Accelerator for cementitious materials, 3 - Coating material powder, 4 - Vibration pan, 5 - Motor, 6 - Eccentric counterweight, 7 - Device base. The dotted line with an arrow in the figure indicates the vibration direction of the particles and powder;

[0028] 8 - Accelerator for cementitious materials, 9 - Coating material powder, 10 - Lubricant. Specific embodiments

[0029] To enable those skilled in the art to better understand the technical solutions and effects of the present invention, several embodiments will be provided below. Obviously, what is described below is only an embodiment, which does not limit the protection scope of the present invention.

[0030] Embodiment 1

[0031] A method for dry - preparing thermally - induced rapid - setting capsules includes the following steps:

[0032] Put 75 parts of sodium silicate with a particle size of 1 mm and 25 parts of sodium hydroxide (accelerator for cementitious materials) with a particle size of 0.2 mm into a particle polishing machine (particle vibration device) and pre - heat while vibrating. Among them, the vibration frequency is 200 Hz, the vibration power is 180 W, the pre - heating temperature is 60 °C, and the pre - heating time is 10 min. After the pre - heating is completed, add 10 parts of polycaprolactone powder with a particle size of 0.02 mm and 10 parts of paraffin powder (coating material powder) with a particle size of 0.01 mm at an addition rate of 5 g / min, and heat while vibrating. Among them, the vibration frequency is 300 Hz, the vibration power is 350 W, the heating temperature is 65 °C, and the heating time is 25 min, so that the coating material powder wraps around the surface of the accelerator for cementitious materials. Then, stop heating, add 5 parts of talc powder (lubricant), and continuously stir with a paddle - type stirrer at a stirring rate of 1 rpm until the temperature of the mixed particles in the particle polishing machine drops to room temperature, obtaining thermally - induced rapid - setting capsules. The structural schematic diagram is as Figure 2 shown. The thermally - induced rapid - setting capsules of Embodiment 1 of the present invention are used to test the setting time of the cementitious material paste. Among them, the cementitious material uses P·O42.5 ordinary Portland cement, the water - cement ratio is 0.35, the dosage of water - reducing agent is 0.2% of the dosage of the cementitious material, and the dosage of the capsules is 6% of the dosage of the cementitious material.

[0033] After testing, for the cementitious material paste added with the thermally - induced rapid - setting capsules of Embodiment 1 of the present invention, before excitation, the setting time of the cementitious material paste is 178 min; after excitation, the setting time of the cementitious material paste is 7 min.

[0034] Embodiment 2

[0035] A method for dry - preparing thermally - induced rapid - setting capsules includes the following steps:

[0036] Put 60 parts of sodium silicate with a particle size of 1 mm, 30 parts of sodium hydroxide with a particle size of 0.2 mm, and 10 parts of calcium aluminide (gel cement accelerator) with a particle size of 0.05 mm into a rolling ball machine (particle vibration device) and preheat while vibrating. Among them, the vibration frequency is 50 Hz, and the vibration power is 30 W; the preheating temperature is 90 °C, and the preheating time is 5 min. After the preheating is completed, add 15 parts of polycaprolactone powder with a particle size of 0.02 mm and 10 parts of polyvinyl alcohol powder (coating material powder) with a particle size of 0.0001 mm at an addition rate of 5 g / min, and heat while vibrating. Among them, the vibration frequency is 80 Hz, and the vibration power is 110 W, the heating temperature is 95 °C, and the heating time is 25 min, so that the coating material powder wraps around the surface of the gel cement accelerator. Then, stop heating, add 7 parts of talc powder (lubricant), and continuously stir with an anchor agitator at a stirring rate of 3 rpm until the temperature of the mixed particles in the rolling ball machine drops to room temperature to obtain a thermally induced quick-setting capsule. The structural schematic diagram is as shown in Figure 2 shown.

[0037] Test the setting time of the gel cement paste by applying the thermally induced quick-setting capsule of Example 2 of the present invention. Among them, P·O42.5 ordinary Portland cement is used as the gel cement, the water-cement ratio is 0.35, the dosage of the water-reducing agent is 0.2% of the dosage of the gel cement, and the dosage of the capsule is 6% of the dosage of the gel cement.

[0038] After testing, for the gel cement paste added with the thermally induced quick-setting capsule of Example 2 of the present invention, before excitation, the setting time of the gel cement paste is 150 min; after excitation, the setting time of the gel cement paste is 7 min.

[0039] Example 3

[0040] A method for dry-preparing a thermally induced quick-setting capsule includes the following steps:

[0041] Put 85 parts of sodium silicate with a particle size of 1 mm and 15 parts of sodium aluminate (gel cement accelerator) with a particle size of 0.05 mm into a cylindrical mixer (particle vibration device) and preheat while vibrating. Among them, the vibration frequency is 60 Hz and the vibration power is 50 W; the preheating temperature is 85 °C and the preheating time is 5 min. After the preheating is completed, add 24 parts of paraffin powder with a particle size of 0.002 mm and 6 parts of stearic acid (coating material powder) with a particle size of 0.02 mm at an addition rate of 10 g / min, and heat while vibrating. Among them, the vibration frequency is 120 Hz and the vibration power is 160 W, the heating temperature is 90 °C and the heating time is 20 min, so that the coating material powder wraps on the surface of the gel cement accelerator. Then, stop heating, add 5 parts of graphite powder (lubricant), and continuously stir with a frame stirrer at a stirring rate of 10 rpm until the temperature of the mixed particles in the cylindrical mixer drops to room temperature, obtaining a thermally induced quick-setting capsule. The structural schematic diagram is as Figure 2 shown.

[0042] The thermally induced quick-setting capsule of Example 3 of the present invention was used to test the setting time of the gel cement paste. Among them, P·O42.5 ordinary Portland cement was used as the gel cement, the water-cement ratio was 0.35, the dosage of the water-reducing agent was 0.2% of the dosage of the gel cement, and the dosage of the capsule was 6% of the dosage of the gel cement.

[0043] After testing, for the gel cement paste added with the thermally induced quick-setting capsule of Example 3 of the present invention, before excitation, the setting time of the gel cement paste was 206 min; after excitation, the setting time of the gel cement paste was 9 min.

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that the gel cement accelerator in this comparative example was not coated by the method of the present invention, that is, the gel cement accelerator in this comparative example was only composed of 75 parts of sodium silicate with a particle size of 1 mm and 25 parts of sodium hydroxide with a particle size of 0.2 mm. Its physical diagram is as Figure 3 shown, and it can be seen from Figure 3 that its moisture absorption characteristics cause water to cover its surface, which is significantly different from the thermally induced quick-setting capsule in Figure 4 Example 1. It can be seen from Figure 4 that the surface of the thermally induced quick-setting capsule in Example 1 is a coating material and there is no obvious moisture.

[0046] After adding the gel cement accelerator of this comparative example to the gel cement, the setting time of the gel cement paste was measured to be 6 min. Among them, during the test, P·O42.5 ordinary Portland cement was used as the gel cement, the water-cement ratio was 0.35, the dosage of the water-reducing agent was 0.2% of the dosage of the gel cement, and the dosage of the gel cement accelerator in Comparative Example 1 was 6% of the dosage of the gel cement.

[0047] As can be seen from the test results of Examples 1-3 of the present invention and the comparative examples, before thermal excitation, the setting time of the gelling material in the thermally induced rapid-setting capsules prepared by the method of the present invention is several hundred minutes; after thermal excitation, the setting time of the gelling material is shortened to several minutes, showing no significant difference from the setting time of directly adding a gelling material accelerator to the gelling material. There are obvious differences in the influence of the thermally induced rapid-setting capsules on the setting time of the gelling material before and after thermal excitation, and the thermally induced rapid-setting gel capsules prepared by the present invention can meet the requirement of "solidification on demand".

[0048] The schematic diagram of the preparation process of the thermally induced rapid-setting capsules in each embodiment of the present invention is as Figure 1 shown. During the preparation process, an infrared heating lamp provides heat to heat the materials (including the gelling material accelerator and the coating material powder), and the eccentric counterweight provides a vibration effect for the vibrating pan when rotating, so that the materials (including the gelling material accelerator and the coating material powder) can vibrate and tumble in the vibrating pan, generating frictional collisions, thereby realizing the dry preparation of the thermally induced rapid-setting capsules of the present invention. During the preparation, the gelling material accelerator is first added and heated, and then the coating material powder is added, which adheres to the surface of the gelling material accelerator and melts under the heating condition. After cooling, the coating material powder solidifies on the surface of the gelling material accelerator, and the adhesion between capsule particles is avoided under the vibration effect.

[0049] The above are only the 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 principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a thermal rapid gel capsule by a dry process, characterized in that: The following steps are involved: The gelling material accelerating setting agent is placed in a particle vibration device and vibrated and preheated. After the preheating is completed, the coating material powder is added and heated while vibrating so that the coating material powder is wrapped on the surface of the gelling material accelerating setting agent. Then, the heating is stopped, a lubricant is added, and the mixture is continuously stirred with a stirrer until the temperature of the mixed particles in the particle vibration device drops to room temperature, thereby obtaining a thermally accelerated gel capsule.

2. The method for preparing a thermosensitive gel capsule by dry method according to claim 1, characterized in that: In parts by weight, the usage of each raw material is: the gelling material accelerating agent: 100 parts, the coating material powder: 1-100 parts, and the lubricant: 0.01-50 parts.

3. The method for preparing a thermosensitive gel capsule by dry method according to claim 1, characterized in that: The gelling material accelerating setting agent is one or more of an alkaline accelerating setting agent, a sulfate accelerating setting agent, and an aluminate accelerating setting agent, and the gelling material accelerating setting agent is a solid particle with a particle size of 0.00001-20 mm.

4. The method for preparing a thermosensitive gel capsule by dry method according to claim 3, characterized in that: The alkaline accelerator is one or more of calcium oxide, sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, and calcium hydroxide; the sulfate accelerator is one or more of aluminum sulfate, sodium sulfate, and potassium sulfate; the aluminate accelerator is one or more of sodium aluminate, potassium aluminate, and calcium aluminate.

5. The method for preparing a thermosensitive gel capsule by dry method according to claim 1, characterized in that: The coating material powder is one or more of paraffin powder, polycaprolactone powder, polyethylene powder, polylactic acid powder, polyvinyl alcohol powder, polyethylene glycol powder, stearic acid powder, and agar powder; and the particle size of the coating material powder is 0.000001-2 mm.

6. The method for preparing a thermosensitive gel capsule by dry method according to claim 1, characterized in that: The lubricant is one or more of graphite powder, talc powder, molybdenum disulfide powder, boron nitride powder and polytetrafluoroethylene powder.

7. The method for preparing a thermosensitive gel capsule by dry method according to claim 1, characterized in that: The particle vibration device is one of a ball rolling machine, a particle polishing machine, and a drum mixer; the stirrer is one of a paddle stirrer, an anchor stirrer, and a frame stirrer, and the stirring rate is 0.1-100 rpm.

8. The method for preparing a thermosensitive gel capsule by dry method according to claim 1, characterized in that: The vibration frequency of the vibrating and preheating process is 0.1-100000 Hz, the vibration power is 20-500 W, the preheating temperature is 40-160° C., and the preheating time is 1-30 min.

9. The method for preparing a thermal rapid gel capsule by dry method according to claim 1, characterized in that: The addition rate of the coating material powder is 0.001-1000 g / min.

10. The method for preparing a thermosensitive gel capsule by dry method according to claim 1, characterized in that: The vibration frequency of the vibrating and heating process is 0.1-100000 Hz, the vibration power is 20-500 W, the heating temperature is 40-160° C., and the heating time is 1-120 min.

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