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Microcapsule for self-repairing of cement-based micro-cracks and preparation method of microcapsule

A microcapsule self-repair technology, applied in the field of waterproof building materials, can solve problems such as lack of repair agent, failure of microcapsule capsule wall, and influence on self-repair effect

Active Publication Date: 2018-08-10
SOUTH CHINA UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when the cement-based material has been in normal service for a long time, the microcapsule wall will face the danger of failure. At this time, the adhesive as a repair agent will flow out. When the concrete encounters strong external stress and produces micro-cracks, There is a lack of repairing agent to repair, which affects its self-repairing effect

Method used

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  • Microcapsule for self-repairing of cement-based micro-cracks and preparation method of microcapsule
  • Microcapsule for self-repairing of cement-based micro-cracks and preparation method of microcapsule
  • Microcapsule for self-repairing of cement-based micro-cracks and preparation method of microcapsule

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] First put 13.5g of 37% formaldehyde solution, 5g of urea, and 0g of water in a reaction vessel with a mechanical stirring device and stir evenly, then add sodium hydroxide to adjust the pH to 8.0, and keep stirring at 50°C Heating in a constant temperature water bath for 1 hour to form a urea-formaldehyde resin prepolymer, and cooling to room temperature;

[0037] Then put the cooled urea-formaldehyde resin prepolymer with 5g of calcium nitrate, 0.8g of Span 80, 0.5g of resorcinol, and 0.5g of ammonium chloride in a reaction vessel and mix them evenly, and mix them evenly at 50°C while stirring. Heating in a constant temperature water bath for 40 minutes to obtain an emulsion;

[0038] Slowly add sulfurous acid dropwise to the emulsion to adjust the pH of the system to 2.0, and heat in a constant temperature water bath at 50°C for 1.5 hours while stirring;

[0039] Then heat up to 60°C, and heat in a constant temperature water bath for 1 hour while stirring to obtain a...

Embodiment 2

[0049] Put 12g of 37% formaldehyde solution, 4.5g of urea, and 2g of water in a reaction vessel with a mechanical stirring device and stir evenly, then add triethanolamine to adjust the pH to 8.0, and heat it in a constant temperature water bath at 55°C while stirring 1h, form urea-formaldehyde resin prepolymer, cool to room temperature;

[0050] Put the cooled urea-formaldehyde resin prepolymer and the aqueous solution of 5g sodium silicate, 0.8g Tween 80, 0.4g hydroquinone, 0.6g polyethylene glycol in the reaction vessel and mix evenly, stir while stirring at 55 Heating in a constant temperature water bath at ℃ for 1 hour to obtain an emulsion;

[0051] Slowly add acetic acid dropwise to the emulsion to adjust the pH of the system to 2.5, and heat in a constant temperature water bath at 55°C for 1.5 hours while stirring;

[0052] Then heat up to 65°C, and heat in a constant temperature water bath for 1 hour while stirring to obtain a suspension, at which time the capsule wa...

Embodiment 3

[0057] First put the mixture of 15g37% formaldehyde solution, 5.5g urea and 5g water in a reaction vessel with a mechanical stirring device and stir evenly, add ammonia water to adjust the pH to 8.5, and heat it in a constant temperature water bath at 50°C for 1 hour while stirring , forming a urea-formaldehyde resin prepolymer, cooled to room temperature;

[0058] Then put the cooled urea-formaldehyde resin prepolymer and 6g of sodium metaaluminate, 0.5g of sodium dodecylbenzene sulfonate, 0.4g of polypropylene glycol, and 0.5g of ammonium chloride in a reaction vessel and mix evenly while stirring While heating in a constant temperature water bath at 50°C for 50 minutes, an emulsion was obtained;

[0059] Slowly add sulfuric acid dropwise to the emulsion to adjust the pH of the system to 3.0, and heat in a constant temperature water bath at 50°C for 1.5 hours while stirring;

[0060] Then heat up to 60°C, and heat in a constant temperature water bath for 1.5 hours while sti...

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Abstract

The invention discloses a microcapsule for self-repairing of cement-based micro-cracks and a preparation method of the microcapsule. The microcapsule is formed by coating a capsule core with a capsulewall, wherein the capsule core is mainly a repairing agent which is one or more selected from sodium metaaluminate, sodium silicate and calcium nitrate, the material of the capsule wall is urea-formaldehyde resin. The preparation method utilizes an in-situ polymerization method, and comprises the steps of: performing a reaction between a formaldehyde solution and urea at 50-70 DEG C and under a pH value of 8-9 so as to form prepolymer, cooling the prepolymer to room temperature, adding the repairing agent, an emulsifier and assistants, conducting stirring at 50-70 DEG C for 0.5-1.5 h, acidifying the pH value of the system to 2-4, and performing a reaction; heating to 50-70 DEG C, conducting heat insulation for 1-3 h, carrying out filtration after cooling is conducted, performing washing with distilled water, and drying. According to the microcapsule, when the micro-cracks are formed in concrete under the action of an external force, the repairing agent is released after the capsule wall is broken, and the released repairing agent reacts with unhydrated cement in the micro-cracks so as to produce water-insoluble particles for filling of the micro-cracks, so that a self-repairing effect of the micro-cracks is achieved.

Description

technical field [0001] The invention relates to the technical field of waterproof building materials, in particular to a microcapsule for self-repairing of cement-based micro-cracks and a preparation method thereof. Background technique [0002] As a commonly used building material, concrete is widely used in industries, civil buildings, bridges, road engineering, underground engineering, water conservancy engineering, ports and ocean engineering. However, during the service process of concrete, due to the influence of the external complex environment, tiny cracks and local damage will inevitably appear under the action of external forces, which may cause water seepage and reduce the service life, and seriously endanger the safety of the overall structure. Moreover, with the promotion of commercial concrete, the current situation of micro-cracks has become more prominent. Simply relying on external plugging measures such as traditional crack repairs is not only difficult to ...

Claims

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Application Information

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IPC IPC(8): C04B24/30C08G12/12B01J13/14B01J13/04
Inventor 张心亚李广彦林杰生李富杰
Owner SOUTH CHINA UNIV OF TECH
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