阅读说明：本技术 一种复合结构自修复微胶囊颗粒及其制备方法和应用 (Composite structure self-repairing microcapsule particle and preparation method and application thereof ) 是由 常洪雷 刘健 曲明月 薛志超 陈鲁川 程梦莹 解全一 于 2019-11-06 设计创作，主要内容包括：本发明涉及混凝土用自修复微胶囊颗粒技术领域,尤其涉及一种复合结构自修复微胶囊颗粒及其制备方法和应用。所述微胶囊颗粒由囊芯和囊壁组成,囊芯为修复裂缝的粉体修复剂；囊壁为双层结构,其中,内囊壁包裹在囊芯的外表面,外囊壁包裹在内囊壁表面；且内囊壁的材质为水泥,外囊壁的材质为聚乙烯醇。水泥内囊壁能够提供强度,PVA外囊壁具有良好的成膜和防水性能,解决了微胶囊透水性过高的问题,又使微胶囊具有足够强度,因此保证了囊芯修复剂不因微胶囊搅拌致裂或渗水提前失效,又大大降低了微胶囊对混凝土基体力学性能的负面影响；最终使微胶囊在服役期间发挥自修复作用,及时有效地修复混凝土中的微裂缝,更好地保障混凝土结构的使用寿命。(The invention relates to the technical field of self-repairing microcapsule particles for concrete, in particular to a composite structure self-repairing microcapsule particle and a preparation method and application thereof. The microcapsule particles consist of capsule cores and capsule walls, and the capsule cores are powder repairing agents for repairing cracks; the capsule wall is of a double-layer structure, wherein the inner capsule wall is wrapped on the outer surface of the capsule core, and the outer capsule wall is wrapped on the surface of the inner capsule wall; the inner bag wall is made of cement, and the outer bag wall is made of polyvinyl alcohol. The inner wall of the cement capsule can provide strength, the outer wall of the PVA capsule has good film-forming and waterproof properties, the problem of overhigh water permeability of the microcapsule is solved, and the microcapsule has enough strength, so that the capsule core repairing agent is prevented from cracking or premature failure due to water seepage caused by stirring of the microcapsule, and the negative influence of the microcapsule on the mechanical property of a concrete matrix is greatly reduced; finally, the microcapsule plays a self-repairing role in the service period, so that the microcracks in the concrete are effectively repaired in time, and the service life of the concrete structure is better ensured.)

1. The composite structure self-repairing microcapsule particle is characterized by consisting of a capsule core and a capsule wall, wherein the capsule core is a powder repairing agent for repairing cracks; the capsule wall is of a double-layer structure, wherein the inner capsule wall is wrapped on the outer surface of the capsule core, and the outer capsule wall is wrapped on the surface of the inner capsule wall; the inner capsule wall is made of cement, and the outer capsule wall is made of polyvinyl alcohol.

2. The composite structural self-repairing microcapsule particle of claim 1, wherein the material of the inner capsule wall comprises any one of ordinary cement and quick-hardening cement.

3. The composite structural self-repairing microcapsule particle of claim 1, wherein the powder repair agent comprises the following raw materials: the material comprises, by mass, 30-50% of an expanding agent, 10-20% of silica fume, 15-25% of lime powder and 15-25% of sodium carbonate.

4. The composite structural self-healing microcapsule particle of any one of claims 1 to 3, wherein the composite structural self-healing microcapsule particle is a spherical structure.

5. The preparation method of the composite structure self-repairing microcapsule particle as claimed in any one of claims 1 to 4, characterized by comprising the following steps:

(1) granulating the prepared powder repairing agent to form capsule cores, screening after the granulation is finished, and drying the capsule cores obtained by screening to obtain target capsule cores;

(2) coating cement slurry formed by cement powder on the surface of a target capsule core in a granulation mode, and curing the obtained product to harden the cement slurry to obtain a microcapsule with an inner capsule wall;

(3) and (3) forming a film of the PVA solution on the outer surface of the microcapsule with the inner capsule wall in a coating mode to obtain the microcapsule.

6. The method according to claim 5, wherein in the step (1), the powder repair agent is granulated by:

1) putting the mixed powder part of the prepared repairing agent into a disc granulator, and spraying water on the mixed powder in batches in the rotation process of the granulator to preliminarily agglomerate the powder into a spherical shape to obtain the spherical repairing agent;

2) then, continuously and simultaneously applying mixed powder and water mist on the surface of the spherical repairing agent to ensure that the diameter of the spherical repairing agent is gradually increased in the rolling process until the particle size in the disc is observed to reach the ideal range; then screening out the spherical repairing agent with proper diameter in time;

3) drying the screened-out repair agent in an oven to obtain capsule cores;

preferably, the whole process of granulating the powder repairing agent is carried out in an environment with the temperature of 20 +/-2 ℃ and the relative humidity of 50 +/-5%;

preferably, the diameter of the sieved repair agent is in the range of 1.0-5.0 mm;

preferably, the drying temperature is 60 ℃ and the drying time is 1 to 3 days.

7. The method according to claim 5, wherein in the step (2), the microcapsule having an inner wall is prepared by: laying a layer of cement powder in a chassis of a disc granulator, putting the dried capsule core into a disc, spraying water mist while adding the powder by rotating the disc granulator, uniformly coating the cement powder on microcapsule particles, maintaining the microcapsule particles under the conditions of constant temperature and constant humidity, and hardening the surfaces of the particles to obtain microcapsules with inner capsule walls;

preferably, the constant temperature and humidity conditions are as follows: the temperature is 50 +/-2 ℃, and the relative humidity is 90 +/-5 ℃.

8. The method of claim 5, wherein in the step (3), the PVA solution is filmed onto the outer surface of the microcapsule having an inner capsule wall by:

(i) putting the microcapsule with the inner capsule wall into a pan body of a coating machine, and pouring the PVA solution into a funnel of a spraying system;

(ii) in the process that the pot body rotates clockwise, a high-pressure spray gun is used for spraying PVA solution on the microcapsules with the inner capsule walls in a grading and uniform mode, and hot air flow is blown to remove moisture on the surface layers of particles, so that the PVA solution can form a film quickly;

(iii) after the PVA solution sprayed on the particle surface is completely dried to form a film, performing the next spraying until a uniform and stable PVA film is formed on the particle surface, and thus obtaining the PVA film;

(iV) screening out the bonded particle groups by using a sample separating sieve to obtain the composite structure self-repairing microcapsule particles.

9. The production method according to any one of claims 5 to 8, wherein in the step (3), the concentration of the PVA solution is 5 to 10% by mass;

preferably, the preparation method of the PVA solution is as follows: under the room temperature environment, adding PVA particles and distilled water into a container, uniformly mixing, then sealing the container to prevent water from evaporating, placing the container under a water bath condition to enable the PVA to reach a dissolving temperature after the PVA is hydrated, simultaneously stirring by using a stirrer, and then cooling the solution to the room temperature for later use;

preferably, the initial temperature of the water bath is 25-35 ℃, and the dissolving temperature is 90 +/-5 ℃;

preferably, pigment is also added to the vessel during agitation.

10. Use of the composite strucmre self-healing microcapsule particle of any one of claims 1 to 4 and/or the product made by the process of any one of claims 5 to 9 in the field of construction; preferably for repairing concrete construction cracks.

Technical Field

The invention relates to the technical field of self-repairing microcapsule particles, in particular to a composite structure self-repairing microcapsule particle for repairing concrete cracks and a preparation method and application thereof.

Background

The information disclosed in this background of the invention is only for enhancement of understanding of the general background of the invention and is not necessarily to be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

At present, the concrete is still the most used building material in the world, but the concrete is brittle and is easy to generate a large amount of micro cracks under the influence of factors such as temperature, load and the like. On one hand, the bearing area of the structure is reduced due to the occurrence of cracks in the concrete, so that the strength of the structure is reduced to some extent; on the other hand, the cracks provide fast channels for carbon dioxide, oxygen, moisture and corrosive ions in the external environment to enter the concrete, so that the corrosion of the reinforced concrete structure is accelerated, and the stability, safety and durability of the building are seriously threatened. Therefore, it is very necessary to study how to repair the microcracks generated in the concrete in time to reach the designed service life of the reinforced concrete structure.

Ordinary concrete has certain self-repairing capability due to the secondary hydration action of unhydrated cement around cracks and the crystallization precipitation action of calcium hydroxide, but the self-repairing capability is weak, so that an ideal effect cannot be achieved under natural conditions. In order to repair cracks appearing in concrete, two types of methods, namely an artificial repair method and a self-repair method, are mainly adopted at present. The manual repair method is to find and repair the macro cracks on the concrete surface through regular monitoring and detection. However, this method consumes a lot of manpower and material resources, and cannot find fine cracks in time, and thus cannot solve the problem from an early stage. There are various self-repairing methods, wherein the incorporation of microcapsule particles wrapping a repairing agent into concrete while mixing the concrete is a common and effective method at present. When concrete cracks, the capsule wall of the nearby microcapsule is broken under the action of stress at the tip of the crack, the repairing agent is scattered and dispersed to the periphery of the crack along with water, and a hydration product or an expansive substance is generated and deposited in the crack to achieve the effect of healing the crack. The self-repairing microcapsule particles can automatically induce and repair damage when concrete cracks, so that the durability of the concrete is better guaranteed. Therefore, a large number of scholars at home and abroad are attracted to carry out research and popularization.

In the above process, the preparation of the microcapsules is critical. At present, the microcapsule is mainly prepared by adopting a high polymer material as a capsule wall material. The high molecular material is used as a capsule wall material, has certain waterproof performance, and can protect the repairing agent in the microcapsule from losing efficacy due to contact with moisture before cracks appear. However, such walls do not have high strength and stiffness per se. To facilitate rapid action in repair, the particles of the repair agent inside the microcapsules are generally floppy and have little hardness and strength provided. If the microcapsules are used as raw materials to be mixed into concrete, on one hand, various mechanical properties of a building can be influenced, and the safety of the structure is not facilitated; on the other hand, in the process of stirring concrete, the microcapsules with low strength cannot provide enough bearing capacity protection for the soft repairing agent, and are easily damaged by a stirring machine running at a high speed, so that the repairing damage function cannot be exerted in the later service period.

In addition, there are also microcapsules prepared using inorganic materials such as hardened cement paste as a wall material; however, the inventor researches and discovers that: the strength and hardness of the microcapsule are ensured, but the advantage of high molecular materials does not exist, namely the water permeability of the microcapsule is greatly increased. Once the free water in the concrete enters the interior of the microcapsule through the pores and reacts with the repairing agent, when cracks are generated, the microcapsule is failed, and therefore the self-repairing function cannot be well achieved.

Disclosure of Invention

In order to solve the problem of failure of self-repairing microcapsule particles caused by insufficient strength or overhigh water permeability, the invention provides self-repairing microcapsule particles with a composite structure capsule wall, and the self-repairing microcapsule not only solves the problem of overhigh water permeability of the microcapsule, but also ensures that the microcapsule has enough strength, thereby ensuring that a capsule core repairing agent does not crack or seep water to fail in advance due to microcapsule stirring, and greatly reducing the negative influence of the microcapsule on the mechanical property of a concrete matrix.

The first purpose of the invention is to provide a composite structure self-repairing microcapsule particle.

The second purpose of the invention is to provide a preparation method of the composite structure self-repairing microcapsule particle.

The third purpose of the invention is to provide the composite structure self-repairing microcapsule particle and the application of the preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical means:

the invention discloses a composite structure self-repairing microcapsule particle, which consists of a capsule core and a capsule wall, wherein the capsule core is a powder repairing agent for repairing cracks; the capsule wall is of a double-layer structure, wherein the inner capsule wall is wrapped on the outer surface of the capsule core, and the outer capsule wall is wrapped on the surface of the inner capsule wall; the inner capsule wall is made of cement, and the outer capsule wall is made of polyvinyl alcohol (PVA).

Secondly, the invention discloses a preparation method of the composite structure self-repairing microcapsule particle, which comprises the following steps:

(1) granulating the prepared powder repairing agent to form capsule cores, screening after the granulation is finished, and drying the capsule cores obtained by screening to obtain target capsule cores;

(2) coating cement slurry formed by cement powder on the surface of a target capsule core in a granulation mode, and curing the obtained product to harden the cement slurry to obtain a microcapsule with an inner capsule wall;

(3) and (3) forming a film of the PVA solution on the outer surface of the microcapsule with the inner capsule wall in a coating mode to obtain the microcapsule.

Finally, the invention discloses the application of the composite structure self-repairing microcapsule particle and the product prepared by the preparation method in the field of buildings; such as repairing concrete construction cracks.

Compared with the prior art, the invention has the following beneficial effects:

(1) the inner capsule wall of the cement-based material can provide strength, while the outer PVA capsule wall has good film-forming property and waterproof property, and simultaneously provides annular restraining force for the interior, thereby solving the problem of overhigh water permeability of the microcapsule, ensuring that the microcapsule has enough strength, ensuring that the capsule core repairing agent does not crack or lose efficacy in advance due to the water seepage of the microcapsule during stirring, and greatly reducing the negative influence of the microcapsule on the mechanical property of the concrete matrix; finally, the microcapsule plays a self-repairing role in the service period, so that the microcracks in the concrete are effectively repaired in time, and the service life of the concrete structure is better ensured.

(2) And selecting PVA grains with the highest cost performance and quick-hardening cement in comparison, and determining the PVA film as the outer capsule wall. When the microcapsule is stressed and broken, the outer capsule wall is adhered to the inner capsule wall and falls off together, the repairing agent is released, the loss of the repairing agent is reduced, and the repairing effect is enhanced.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic structural view of a composite self-healing microcapsule particle of example 1 of the present invention; wherein 1 represents the capsule core, 2 represents the capsule wall, 2.1 represents the inner capsule wall, and 2.2 represents the outer capsule wall.

Fig. 2 is a graph showing the effect of the composite self-repairing microcapsule particle prepared in example 1 under an electron microscope.

Fig. 3 is an effect diagram of the composite self-repairing microcapsule particle prepared in example 1 under an electron microscope after being soaked.

FIG. 4 is a diagram of the effect of the composite self-repairing microcapsule particle prepared in example 1 under an electron microscope after being cut and soaked.

FIG. 5 is a comparison graph of the compressive strength of the test pieces before and after the composite self-repairing microcapsule particles prepared in example 1 of the present invention are incorporated.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

As described above, when a high molecular material or a cement-based material is used alone as a capsule wall material, there is a problem that self-repairing microcapsule particles fail due to insufficient strength or excessive water permeability. Therefore, the invention provides a self-repairing microcapsule particle with a composite structure capsule wall, which can well solve the existing problems and further explain the technical scheme.

In some typical embodiments, the composite-structured self-healing microcapsule particles are spherical structures.

In some exemplary embodiments, the material of the inner bag wall includes ordinary cement, quick-hardening cement, and the like.

In some exemplary embodiments, the powder repair agent comprises the following raw materials: the material comprises, by mass, 30-50% of an expanding agent, 10-20% of silica fume, 15-25% of lime powder and 15-25% of sodium carbonate. Because the pure cement components are used as the repairing agent which is proved to have unobvious repairing effect, mineral admixtures and proportions suitable for repairing cracks need to be researched.Wherein, the expanding agent is selected from one with the best performance, namely calcium sulphoaluminate expanding agent (CSA expanding agent). After the expanding agent meets water, the overall hydration degree of the repairing agent can be improved, the content of hydration products is increased, and calcium sulphoaluminate and calcium oxide components in the expanding agent and the water are subjected to chemical reaction to respectively form a certain amount of AFT and CH, so that volume expansion is generated, the volume stability is improved, and the repairing agent plays an important role in repairing cracks. The silica fume has no hydration property, but contains a large amount of high-activity SiO ₂On the one hand, it will react with Ca (OH) which is one of the cement hydration products ₂Reacting to generate low-alkalinity calcium silicate hydrate gel, wherein the compact hydrate is stable and insoluble and is filled in gaps; on the other hand, Ca (OH) in the cement matrix ₂The concentration of (2) is reduced, and the speed of hydration reaction is accelerated. The water consumption can be obviously reduced by adding the quicklime powder, so that the aims of reducing the water-gel ratio of the capsule core repairing agent, ensuring the softness of the repairing agent and improving the strength and durability after repairing are fulfilled; in addition, the main component of the fertilizer is calcium oxide which is mixed with CO when meeting water ₂Then calcium hydroxide and calcium carbonate are generated in turn, which can bond the cracked structure again. The sodium carbonate is easy to deliquesce in a humid environment, absorbs carbon dioxide and moisture, partially changes into sodium bicarbonate to fill cracks, reduces the intrusion of carbon dioxide into a structure and reduces the corrosion to reinforcing steel bars; most importantly, the calcium carbonate can provide a large amount of carbonate ions and Ca in the quicklime ⁺²Combined formation of CaCO ₃And the repair of the crack is realized. The mineral admixtures are mixed together according to the optimal proportion obtained by experiments, the advantages of the mineral admixtures can be respectively exerted, the matrix with cracks is finally healed, the safety and the durability of the structure are continuously guaranteed, and the designed service life is reached.

In some exemplary embodiments, in step (1), the method for granulating the powder repair agent is as follows:

1) putting the mixed powder part of the prepared repairing agent into a disc granulator, and spraying water on the mixed powder in batches in the rotation process of the granulator to preliminarily agglomerate the powder into a spherical shape to obtain the spherical repairing agent;

2) then, continuously and simultaneously applying mixed powder and water mist on the surface of the spherical repairing agent to ensure that the diameter of the spherical repairing agent is gradually increased in the rolling process until the particle size in the disc is observed to reach the ideal range; then screening out the spherical repairing agent with proper diameter in time;

3) and (4) drying the screened-out shape repairing agent in an oven to obtain the capsule core.

Further, the whole process of granulating the powder repairing agent is carried out in an environment with the temperature of 20 +/-2 ℃ and the relative humidity of 50 +/-5%.

Further, the diameter range of the screened spherical repairing agent is 1.0-5.0 mm.

Further, the drying temperature is 60 ℃, and the drying time is 1-3 days.

In some typical embodiments, in step (2), the microcapsule with inner wall is prepared by: laying a layer of cement powder in a chassis of a disc granulator, putting the dried capsule core into a disc, spraying water mist while adding the powder by rotating the disc granulator, uniformly coating the cement powder on microcapsule particles, curing under the conditions of constant temperature and constant humidity, and obtaining the microcapsule with an inner capsule wall after the surfaces of the particles are hardened.

Further, the constant temperature and humidity conditions are as follows: the temperature is 50 +/-2 ℃, and the relative humidity is 90 +/-5 ℃.

In some exemplary embodiments, in step (3), the concentration of the PVA solution is 5 to 10% by mass.

Further, the preparation method of the PVA solution comprises the following steps: under the room temperature environment, PVA particles and distilled water are added into a container and uniformly mixed, then the container is sealed to prevent water from evaporating, after PVA hydration is completed, the container is placed in a water bath condition to enable PVA to reach the dissolving temperature, a stirrer is used for stirring, and then the solution is cooled to the room temperature for standby.

Further, the initial temperature of the water bath is 25-35 ℃, and the dissolution temperature is 90 +/-5 ℃.

Further, pigment can be added into the container during stirring to ensure that whether the PVA solution completely coats the inner capsule wall is identified during subsequent preparation of the outer capsule wall. In addition, the speed is appropriate during stirring, a large amount of bubbles are generated due to an excessively high speed, and the speed is too low to achieve the dispersing effect until a PVA solution with good uniformity, stability and fluidity is formed.

In some typical embodiments, in step (3), the method for forming the PVA solution into a film on the outer surface of the microcapsule having an inner capsule wall is:

(i) the microcapsule with inner capsule wall is set inside the pot of coating machine, PVA solution is poured into the funnel of spraying system, and the work frequency of the spray gun and the atomizing area of the nozzle are regulated to make the PVA solution atomized homogeneously and have large spraying area.

(ii) In the process that the pot body rotates clockwise, the PVA solution is sprayed on the microcapsule with the inner capsule wall by a high-pressure spray gun in a grading and uniform mode, and meanwhile hot air flow is blown to remove moisture on the surface layer of particles, so that the PVA solution can be rapidly formed into a film.

(iii) And after the PVA solution sprayed on the surfaces of the particles is completely dried to form a film, performing the next spraying process until uniform and stable PVA films are formed on the surfaces of the particles, thus obtaining the PVA film. Thus, the thickness of the PVA capsule wall can be controlled by the quality and the times of spraying the solution in each round; in addition, the coating machine has polishing effect, so that the prepared granules have smooth and spherical surfaces.

(iV) screening out the bonded particle groups by using a sample separating sieve to obtain the composite structure self-repairing microcapsule particles.

The invention is further described with reference to the following figures and detailed description.