CN115536329A - Self-repairing particles, self-repairing cement-based composite material and preparation method thereof - Google Patents
Self-repairing particles, self-repairing cement-based composite material and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/02—Making microcapsules or microballoons
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/27—Water resistance, i.e. waterproof or water-repellent materials
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The invention discloses a self-repairing particle, a self-repairing cement-based composite material and a preparation method thereof, wherein the self-repairing particle comprises an inner core, a waterproof layer and an outer shell; the waterproof layer is a resin film and is coated on the outer surface of the inner core material; the shell is a cement shell; the inner core comprises the following components in parts by mass: 5 to 7 parts of sodium carbonate, 1 to 3 parts of silica fume, 1 to 3 parts of silicon dioxide, 5 to 7 parts of quicklime, 1 to 2 parts of magnesia expanding agent and 1 to 2 parts of bentonite. When the self-repairing particles are cracked under the tip stress, the repairing agent in the self-repairing particles can be gradually dissolved in water to generate a repairing substance carbonate ions, the repairing substance carbonate ions are compounded with calcium ions in the cement matrix material to form calcium carbonate precipitates, and the calcium carbonate precipitates are filled in microcracks for repairing. The waterproof layer on the outer layer of the inner core material can reduce the water absorption of the self-repairing particles, can prevent water from entering in advance, prevents the repairing agent from reacting with substances in the cement matrix in advance, and ensures that the repairing agent can play a role after the microcracks appear.
Description
Technical Field
The invention belongs to the technical field of building materials, and relates to a self-repairing particle, a self-repairing cement-based composite material and a preparation method thereof.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
Concrete is used as a building material with high compressive strength, good durability and low price, and is widely applied to the civil engineering industry at present. However, the tensile strength of concrete is far lower than the compressive strength, so that cracks are easily generated during the use process, particularly under the condition of external load, and the bearing capacity, durability and safety of the whole structure are affected.
The related technologies of cement-based material self-repair mainly comprise microcapsule self-repair, mineral cement-based self-repair, electrochemical deposition self-repair, shape memory alloy self-repair, microorganism self-repair and the like. However, each repair technology has its limitations at present, and there is a further optimization space, for example, the manufacturing process of the microcapsule material is complex and expensive; the electrochemical deposition and shape memory alloy self-repairing repair conditions are special and difficult to apply to practical engineering; the long-term activity of the microorganism in the concrete is difficult to ensure, and the repairing effect is not obvious.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a self-repairing particle, a self-repairing cement-based composite material and a preparation method thereof. The self-repairing composite material is based on the self-repairing principle of microcapsules, minerals and permeable crystals, and the influence of the coupling effect of the self-repairing particles and the permeable crystals on the self-repairing performance of the cement-based material is utilized, so that the composite material can more effectively repair cracks in and on the surface of concrete.
In order to achieve the purpose, the invention is realized by the following technical scheme:
in a first aspect, the present invention provides a self-healing particle, comprising an inner core, a waterproof layer, and an outer shell; the waterproof layer is a resin film and is coated on the outer surface of the inner core material; the shell is a cement shell;
the inner core comprises the following components in parts by mass: 5 to 7 parts of sodium carbonate, 1 to 3 parts of silica fume, 1 to 3 parts of silicon dioxide, 5 to 7 parts of quicklime, 1 to 2 parts of magnesia expanding agent and 1 to 2 parts of bentonite.
In a second aspect, the present invention provides a method for preparing the self-repairing particle, comprising the following steps:
putting sodium carbonate, silica fume, silicon dioxide, quicklime, a magnesium oxide expanding agent and bentonite into a granulator according to a certain proportion, spraying water for granulation, and drying granules to obtain an inner core;
coating the resin on the surface of the inner core to form a waterproof layer;
and finally, uniformly adhering cement powder on the surface of the waterproof layer to form a shell, thus obtaining the waterproof paint.
In a third aspect, the invention provides a self-repairing cement-based composite material based on self-repairing particles, which comprises 30-40 parts by weight of a cement matrix material and 1-3 parts by weight of a self-repairing material,
the self-repairing material comprises the self-repairing particles and a permeable crystallization additive, wherein the mass ratio of the self-repairing particles to the permeable crystallization additive is 55-70.
In a fourth aspect, the preparation method of the self-repairing cement-based composite material comprises the following steps: fully mixing the portland cement, the fly ash, the quartz sand and the self-healing particles;
and then adding a permeable crystallization additive, a water reducing agent and water into the mixture, and fully stirring to obtain the water reducing agent.
The beneficial effects achieved by one or more of the embodiments of the invention are as follows:
(1) According to the self-repairing particles, the epoxy resin is used as a waterproof layer to wrap the effective components of the self-repairing particles, so that water molecules are prevented from entering, and the phenomenon that the water molecules react prematurely and lose the self-repairing effect is avoided.
The outermost layer is wrapped by a layer of ordinary portland cement shell, so that the strength of the self-repairing particles is improved, the self-repairing particles are prevented from being damaged and losing efficacy prematurely in the process of preparing the self-repairing cement-based composite material, and the long-term effectiveness of the repairing effect is ensured. And the self-repairing particles have good compatibility with the cement-based material, and a weak surface is prevented from appearing in an interface transition region of the self-repairing particles and the cement-based material. The self-repairing particles can replace part of fine aggregate to be added into cement mortar.
The strength of the core part of the self-repairing particles is low, most of the self-repairing particles can crack from the middle after cracks appear on a cement mortar matrix, and the cracks can ensure that the repairing substances in the self-repairing particles are separated out in water so as to repair the cracks.
The self-repairing particles can heal cracks of about 1mm at most, the repairing time is short, the self-healing can be realized under the water curing condition without additional external conditions, the main healing product of the cracks is calcite precipitation, and the self-repairing particles also comprise C-S-H gel and other self-healing products.
The self-repairing cement-based composite material is maintained in seawater, the area repairing rate is rapidly improved in the early stage, and the final area repairing rate is higher. The method has important significance for the fact that the cracks can be healed more quickly and further corrosion can be prevented in ocean engineering.
Compared with a single self-repairing component, the self-repairing particles and the permeable crystallization additive provided by the invention have the advantages that the compressive strength recovery rate of the material is obviously improved and the relative permeability coefficient of the material is obviously reduced under the coupling effect of a certain proportion.
The self-repairing particles provided by the invention can repair macroscopic visible cracks of the material, the added permeable crystallization master batch repairs tiny cracks in the material, self-healing at macroscopic and microscopic angles is realized under the coupling action of the self-repairing particles and the permeable crystallization master batch, and the self-healing efficiency of the cement-based material is greatly promoted.
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 included to illustrate an exemplary embodiment of the invention and not to limit the invention.
FIG. 1 is a graph of self-healing particle structures of different particle sizes produced in examples 2 and 3 of the present invention.
Fig. 2 is a fracture surface diagram of self-healing cement-based materials prepared in examples 2 (a) and 3 (b) of the present invention.
Fig. 3 is a comparison chart of the crack self-repairing effect of the self-repairing cement-based material prepared in examples 1, 2, 3 and 4 of the present invention, wherein (a) is the effect after the crack repair of example 1, (b) is the effect after the crack repair of example 2, (c) is the effect after the crack repair of example 3, and (d) is the effect after the crack repair of example 4.
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.
In a first aspect, the invention provides a self-repairing particle, which comprises an inner core, a waterproof layer and an outer shell; the waterproof layer is a resin film and is coated on the outer surface of the inner core material; the shell is a cement shell;
the inner core comprises the following components in parts by mass: 5 to 7 parts of sodium carbonate, 1 to 3 parts of silica fume, 1 to 3 parts of silicon dioxide, 5 to 7 parts of quicklime, 1 to 2 parts of magnesia expanding agent and 1 to 2 parts of bentonite.
The self-repairing particles are smooth spherical, the powder repairing agent of the inner capsule core is softer, when the self-repairing particles break under tip stress, the repairing agent inside the self-repairing particles can be gradually dissolved in water and generate repairing substance carbonate ions, the repairing substance carbonate ions and calcium ions in the cement matrix material are compounded to form calcium carbonate precipitates, and the calcium carbonate precipitates are filled in microcracks for repairing.
The epoxy resin waterproof layer on the outer layer of the inner core material can reduce the water absorption rate of the self-repairing particles, can prevent water from entering in advance, prevents the repairing agent from reacting with substances in the cement matrix in advance, and ensures that the repairing agent can play a role after micro cracks appear, thereby ensuring the long-term effectiveness of the repairing effect. In addition, compared with microbial self-repair, the self-repair particles have long-term activity and are more favorable for repairing cracks in concrete.
The outmost layer of the self-repairing particles is a cement shell, has certain hardness, can improve the strength of the self-repairing particles, and has good compatibility with a cement-based material, so that when the cement-based material is doped into a cement mortar mixture, the integrity can be kept, and the self-repairing particles are prevented from being damaged and losing efficacy prematurely in the process of preparing the self-repairing cement-based composite material.
The shell of the self-repairing particles is made of cement, in the hydration process of cement mortar, the shell of the self-repairing particles and the cement cementing material in the cement mortar can simultaneously undergo the hydration process, the shell and the cement cementing material are well integrated, the self-repairing particles and the cement base material have good compatibility, and weak surfaces are prevented from appearing in an interface transition area of the self-repairing particles and the cement base material. The self-repairing particles can replace part of fine aggregate to be added into cement mortar.
The higher the carbon source content of the self-repairing particles is, the better the self-healing efficiency is. The calcium hydroxide can be precipitated from the cement matrix to supplement a calcium source, and the carbonate dissolved in water in the carbon dioxide in the air is relatively less, so that the carbonate difference in the self-repairing particles cannot be completely compensated; compared with the maintenance of a sample with cracks generated by deionized water in seawater, the area repair rate is rapidly improved in the early stage, and the final area repair rate is higher. This is because binding ions in the seawater can promote the efficiency and rate of self-healing. The method has important significance for the fact that the crack can be healed more quickly and further erosion can be prevented in ocean engineering.
The effects of each component in the inner core material are respectively as follows:
sodium carbonate: the cement-based material can separate out calcium hydroxide in water. Sodium carbonate is soluble in water and reacts with calcium ions to form calcium carbonate filled cracks.
Silica fume, silica: the silica fume and nanosilica can provide highly reactive silica and react with calcium hydroxide to form hydrated calcium carbonate gels (C-S-H), can fill cracks, and improve cohesion between repair products.
Quicklime: the quicklime can provide calcium and an alkaline environment to capture carbon dioxide to generate carbonate ions, so that the amount of crack repair products is increased, and self repair is better realized.
Magnesium oxide swelling agent, bentonite: the magnesium oxide expanding agent and the bentonite have water expansion characteristics, and after the inner core material of the self-healing particles is dissolved in water, the inner core material can expand to fill the reserved holes, so that the cement base is prevented from generating holes to reduce the strength of the cement.
In some embodiments, the waterproof layer is made of epoxy resin. The epoxy resin has the characteristic of good viscosity, can uniformly wrap the inner core of the self-repairing particle, and can also bond cement powder to generate a shell. Most importantly, the epoxy resin and the curing agent are cured to form a waterproof layer after reaction, and the waterproof layer has a good waterproof effect.
In some embodiments, the cement sheath is made of portland cement or sulphoaluminate cement.
In some embodiments, the self-healing particles have a particle size of 1 to 5mm;
preferably, when the particle size of the self-repairing particles is 1-2mm, the thickness of the waterproof layer is 0.1-0.2mm, and the thickness of the cement shell is 0.2-0.4mm;
when the particle size of the self-repairing particles is 2-4mm, the thickness of the waterproof layer is 0.1-0.3mm, and the thickness of the cement shell is 0.2-0.5mm.
The cement shell self-repairing particle is characterized by totally relating to two self-repairing particles with different particle sizes, wherein the particle sizes are respectively 1-2mm and 2-4mm, the self-repairing particles with the same quality have large specific surface area of small particles, the cement shell has more specific gravity, the proportion of repairing components is reduced, and the influence of the self-repairing particles on the area repairing rate has no obvious difference. The grain diameter of 2-4mm has larger inner core/outer shell ratio, and the self-healing particles with the same quality can carry more repairing substances. The self-repairing particles with the particle size of 1-2mm have better dispersibility and can be uniformly dispersed in cement mortar, and when cracks occur, the self-repairing particles can be uniformly distributed at the cracks. The mutual influence of the advantages and the disadvantages of the two particle sizes causes the influence of the particle size of the self-repairing particles on the self-healing efficiency to be insignificant.
In a second aspect, the present invention provides a method for preparing the self-repairing particle, comprising the following steps:
putting sodium carbonate, silica fume, silicon dioxide, quicklime, a magnesium oxide expanding agent and bentonite into a granulator according to a certain proportion, spraying water for granulation, and drying granules to obtain an inner core;
coating the resin on the surface of the inner core to form a waterproof layer;
and finally, uniformly adhering cement powder on the surface of the waterproof layer to form a shell, thus obtaining the waterproof paint.
The self-repairing particle inner core material has no reaction among all substances in the granulation process, ensures the functionality of the self-repairing particles, and can generate sufficient repairing products to fill microcracks through a series of physical and chemical reactions when cement cracks.
In some embodiments, the method for coating the resin on the surface of the inner core specifically comprises:
and putting the inner core into the mixed solution of the resin and the curing agent, stirring to ensure that the surface of the inner core is completely coated by the resin, fishing out the inner core, and draining off the redundant resin.
The mass ratio of the epoxy resin to the curing agent is 1:1.
preferably, the method for adhering the cement powder comprises the following steps:
spreading the filtered inner core wrapped with the resin layer in cement powder, and rolling to make the cement powder adhere to the outer surface of the inner core; and screening out excessive cement powder, and curing.
The inclination angle of the disc granulator is adjusted to be 45 degrees, the rotating speed is 30r/min, until the particle size in the disc is observed to reach the required range, and the granulation time of the inner core material is about 5-10 min.
After the preparation of the inner core of the self-repairing particle is finished, the inner core of the self-repairing particle is placed in a drying box at 40 ℃ to be dried for 24 hours, so that the effective components in the self-repairing particle can not react in advance, and the long-term effectiveness of the repairing effect is ensured.
The prepared self-repairing particles are placed in a constant temperature and humidity box (the temperature is 50 ℃, and the relative humidity is 90 percent), and the self-repairing particles with certain hardness on the shells and soft inner cores are obtained after the self-repairing particles are stored for a period of time.
In a third aspect, the invention provides a self-repairing cement-based composite material based on self-repairing particles, which comprises 30-40 parts of a cement matrix material and 1-3 parts of a self-repairing material by weight, wherein,
the self-repairing material comprises the self-repairing particles and a permeable crystallization additive, wherein the mass ratio of the self-repairing particles to the permeable crystallization additive is (4-6).
The permeable crystallization additive is crack self-healing cement-based permeable crystallization active master batch produced by Prowa science and technology Limited.
The permeable crystallization additive is an active additive, and is a core additive specially used for producing cement-based permeable crystallization waterproof paint.
The self-repairing particles are divided into three types of particles which crack from the middle, crack along a shell layer and do not crack in cement mortar. For three types and two types of particle size self-repairing particles, because the strength of the inner core part of the self-repairing particles is low, most of the self-repairing particles can crack from the middle after a crack of a cement mortar matrix occurs, but the self-repairing particles can be triggered to crack after the crack occurs instead of cracking along an interface transition area of the self-repairing particles and the cement matrix, and the crack can ensure that internal repairing substances are separated out in water so as to repair the crack.
In some embodiments, the cement matrix material consists of the following components in parts by weight:
120-140 parts of Portland cement, 60-80 parts of fly ash, 60-70 parts of quartz sand, 60-90 parts of water and 1-2 parts of water reducing agent.
The fly ash (such as I-grade fly ash) is selected to replace part of ordinary portland cement, so that the workability of mortar can be improved to a certain extent, the cement consumption is reduced, the cost is reduced, the pollution to the environment is reduced, part of solid waste is utilized, and in addition, the cement matrix material can have higher toughness.
Preferably, the cement matrix material consists of the following components in parts by weight: 125-135 parts of Portland cement, 65-75 parts of fly ash, 60-65 parts of quartz sand, 70-80 parts of water and 1-1.5 parts of water reducing agent.
Each component in the cement matrix material forms a matrix structure of the self-repairing material. The shell of the self-repairing particle structure is a cement component, can be well combined with a cement matrix material, has good compatibility, and cannot generate a weak surface at an interface, so that the improvement and the guarantee cannot greatly reduce the strength of the material, and cannot generate damage at the interface of the self-repairing particles and the cement matrix. The self-repairing particles can be uniformly dispersed in the matrix material, and the repairing effect is improved after cracks appear.
Preferably, the particle size of the quartz sand is 80-120 meshes.
In some embodiments, the mass ratio of the cement matrix material to the self-healing material is 34-36.
In some embodiments, the mass percentage of the self-healing particles in the self-healing material is 55-70%, such as 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%.
In some embodiments, the water reducer is a liquid polycarboxylic acid high efficiency water reducer.
In a fourth aspect, the preparation method of the self-repairing cement-based composite material comprises the following steps: fully mixing the portland cement, the fly ash, the quartz sand and the self-healing particles;
and then adding a permeable crystallization additive, a water reducing agent and water into the mixture, and fully stirring to obtain the water reducing agent.
The self-repairing particles are added firstly, so that the self-repairing particles can be uniformly distributed in the cement, and then water and the water reducing agent are added, so that the self-repairing particles can be uniformly dispersed in the repairing cement-based composite material, and the self-repairing function can be well achieved no matter where cracks occur.
If cement-based composite materials with different self-repairing particle contents are prepared, the cement-based composite materials with unchanged self-repairing particle contents can be prepared by replacing part of quartz sand with self-repairing particles with equal mass.
After being prepared into a sample, the sample is respectively placed in deionized water and seawater, and the difference of self-repairing efficiency of the self-repairing cement-based composite material in different underwater environments is simulated. The seawater is sampled in coastal areas of Qingdao China, wherein the ion content is Mg 2+ 1157.5mg/L、K + /Na + 10511.03mg/L、Ca 2+ 1286.57mg/L、Cl - 18091.03mg/L、SO 4 2- 2852.26mg/L、HCO 3 - 141.41mg/L、CO 3 2- 6.05mg/L。
The present invention will be further described with reference to the following examples.
Example 1
A preparation method of a self-repairing cement-based composite material comprises the following steps:
the method comprises the following steps: the preparation method of the self-repairing particle comprises the following steps:
(1) Weighing a self-repairing particle inner core material, wherein the self-repairing particle inner core material comprises the following components in parts by mass: 1 part of sodium carbonate, 1 part of silica fume, 1 part of silicon dioxide, 5 parts of quicklime and 1 part of bentonite.
(2) And (3) putting the prepared inner core material into a disc granulator, wherein the inclination angle of the disc granulator is adjusted to 45 degrees, and the rotating speed is 30r/min.
(3) Spraying deionized water on the mixed powder in batches, taking out and sieving after the particles are formed into balls, and placing the balls in a drying box at 40 ℃ to dry for 24 hours to obtain the prepared self-repairing particle inner core.
(4) And (2) rapidly and uniformly stirring the epoxy resin and the curing agent according to the mass ratio of 1.
(5) In order to prevent the samples from being adhered to each other, the filtered samples are quickly spread in ordinary portland cement, and the samples are slightly rubbed in the cement powder, so that the cement powder is uniformly adhered to the surfaces of the samples to form an outer protective shell. And finally, screening excessive cement powder by using a sieve, screening self-healing particles with the particle size of 1-2mm, and storing for later use after the epoxy resin is completely cured.
Step two: weighing a self-repairing cement matrix material, wherein the self-repairing cement matrix material comprises the following components in parts by mass: 81.1 parts of cement matrix material and 2.5 parts of self-repairing particles.
The cement matrix material comprises the following components in parts by weight: 32.5 parts of cement, 17.5 parts of fly ash, 16 parts of water, 15 parts of quartz sand and 0.1 part of water reducing agent.
Step three: the weighed materials are sequentially placed in a stirrer and fully stirred.
Step four: the material after thorough stirring was placed in a mould, demoulded after 24 hours and then stored in a standard curing chamber (20 ± 2 ℃ and 95% relative humidity) for 7 days.
Step five: the ordinary cement-based composite material after being cured for 7 days is subjected to prepressing treatment through a splitting tensile strength test to generate cracks, and then the treated sample is placed in seawater (20 +/-2 ℃) to test the area repair rate and the relative permeability coefficient after 28 days, as shown in table 1.
Example 2
A preparation method of a self-repairing cement-based composite material comprises the following steps:
the method comprises the following steps: self-healing particles were prepared according to the procedure for preparation one of example 1.
Step two: weighing a self-repairing cement matrix material, wherein the self-repairing cement matrix material comprises the following components in parts by mass: 81.1 parts of cement matrix material and 2.5 parts of self-repairing particles.
The cement matrix material comprises the following components in parts by weight: 32.5 parts of cement, 17.5 parts of fly ash, 16 parts of water, 15 parts of quartz sand and 0.1 part of water reducing agent.
Step three: the weighed materials are sequentially placed in a stirrer and fully stirred.
Step four: the material after thorough stirring was placed in a mold, demolded after 24 hours, and then cured in a standard curing room (20 ± 2 ℃ and 95% relative humidity) for 7 days.
Step five: the ordinary cement-based composite material after being cured for 7 days is subjected to prepressing treatment through a splitting tensile strength test so as to generate cracks, and then the treated sample is placed in deionized water (20 +/-2 ℃) to test the area repair rate and the relative permeability coefficient after 28 days, as shown in table 1.
Example 3
A preparation method of a self-repairing cement-based composite material comprises the following steps:
the method comprises the following steps: the preparation method of the self-repairing particle comprises the following steps:
(1) Weighing a self-repairing particle inner core material, wherein the self-repairing particle inner core material comprises the following components in parts by mass: 1 part of sodium carbonate, 1 part of silica fume, 1 part of silicon dioxide, 5 parts of quicklime and 1 part of bentonite.
(2) And (3) putting the prepared inner core material into a disc granulator, wherein the inclination angle of the disc granulator is adjusted to 45 degrees, and the rotating speed is 30r/min.
(3) Spraying deionized water on the mixed powder in batches, taking out and sieving after the particles are formed into balls, and placing the balls in a drying box at 40 ℃ to dry for 24 hours to obtain the prepared self-repairing particle inner core.
(4) And (3) rapidly and uniformly stirring the epoxy resin and the curing agent, putting the prepared inner core into the epoxy resin, rapidly stirring to ensure that the surface of the inner core is completely coated by the epoxy resin, fishing out by using a strainer, draining off the redundant epoxy resin, and forming a transparent film on the surface of the inner core to form a waterproof layer.
(5) In order to prevent the samples from being adhered to each other, the filtered samples are quickly spread in ordinary portland cement, and the samples are slightly rubbed in the cement powder, so that the cement powder is uniformly adhered to the surfaces of the samples to form an outer protective shell. And finally, screening redundant cement powder by using a screen, screening self-healing particles with the particle size of 2-4mm, and storing for later use after the epoxy resin is completely cured.
Step two: weighing a self-repairing cement matrix material, wherein the self-repairing cement matrix material comprises the following components in parts by mass: 81.1 parts of cement matrix material and 2.5 parts of self-repairing particles.
The cement matrix material comprises the following components in parts by weight: 32.5 parts of cement, 17.5 parts of fly ash, 16 parts of water, 15 parts of quartz sand and 0.1 part of water reducing agent.
Step three: the weighed materials are sequentially placed in a stirrer and fully stirred.
Step four: the material after thorough stirring was placed in a mold, demolded after 24 hours, and then cured in a standard curing room (20 ± 2 ℃ and 95% relative humidity) for 7 days.
Step five: the ordinary cement-based composite material after being cured for 7 days is subjected to prepressing treatment through a splitting tensile strength test so as to generate cracks, and then the treated sample is placed in deionized water (20 +/-2 ℃) to test the area repair rate and the relative permeability coefficient after 28 days, as shown in table 1.
The structures of the self-healing particles of different particle sizes prepared in examples 2 and 3 are shown in FIG. 1.
Example 4
A preparation method of a self-repairing cement-based composite material comprises the following steps:
the method comprises the following steps: the preparation method of the self-repairing particle comprises the following steps:
(1) Weighing a self-repairing particle inner core material, wherein the self-repairing particle inner core material comprises the following components in parts by mass: 6 parts of sodium carbonate, 1 part of silica fume, 1 part of silicon dioxide and 1 part of bentonite.
(2) And (3) putting the prepared inner core material into a disc granulator, wherein the inclination angle of the disc granulator is adjusted to 45 degrees, and the rotating speed is 30r/min.
(3) Spraying deionized water on the mixed powder in batches, taking out and sieving after the particles are formed into balls, and placing the balls in a drying box at 40 ℃ for drying for 24 hours to obtain the prepared self-repairing particle inner core.
(4) And (3) rapidly and uniformly stirring the epoxy resin and the curing agent, putting the prepared inner core into the epoxy resin, rapidly stirring to completely coat the surface of the inner core with the epoxy resin, taking out the inner core with a strainer, draining off the redundant epoxy resin, and forming a transparent film on the surface of the inner core to form a waterproof layer.
(5) In order to prevent the samples from being adhered to each other, the filtered samples are quickly spread in ordinary portland cement, and the samples are slightly rubbed in the cement powder, so that the cement powder is uniformly adhered to the surfaces of the samples to form an outer protective shell. And finally, screening excessive cement powder by using a screen, screening self-healing particles with the particle size of 2-4mm, and storing for later use after the epoxy resin is completely cured.
Step two: weighing a self-repairing cement matrix material, wherein the self-repairing cement matrix material comprises the following components in parts by mass: 81.1 parts of cement matrix material and 2.5 parts of self-repairing particles.
The cement matrix material comprises the following components in parts by weight: 32.5 parts of cement, 17.5 parts of fly ash, 16 parts of water, 15 parts of quartz sand and 0.1 part of water reducing agent.
Step three: the weighed materials are sequentially placed in a stirrer and fully stirred.
Step four: the material after thorough stirring was placed in a mould, demoulded after 24 hours and then stored in a standard curing chamber (20 ± 2 ℃ and 95% relative humidity) for 7 days.
Step five: the ordinary cement-based composite material after being maintained for 7 days is subjected to prepressing treatment through a splitting tensile strength test so as to generate cracks, and then the treated sample is placed in deionized water (20 +/-2 ℃) to test the area restoration rate, the relative permeability coefficient, the compressive strength recovery rate and the porosity after 28 days, as shown in table 1.
As can be seen from the graph 2, the fracture interface of the self-repairing cement-based material internally comprises a plurality of self-repairing particles, the self-repairing particles in the fracture interface are uniformly dispersed, most of the self-repairing particles on the fracture interface crack from the middle and along the shell layer, and the self-repairing components can be effectively released.
In fig. 3, the upper part is a fracture diagram of the self-repairing cement-based material, and the lower part is a diagram after repair, the comparison before and after repairing the crack can be seen, and the crack is basically healed after a certain period of time of repair.
Example 5
A preparation method of a self-repairing cement-based composite material comprises the following steps:
the method comprises the following steps: self-healing particles were prepared according to the preparation method of example 4.
Step two: weighing a self-repairing cement matrix material, wherein the self-repairing cement matrix material comprises the following components in parts by mass: 81.1 parts of cement matrix material, 2.5 parts of self-repairing particles and 1 part of permeable crystallization additive.
The cement matrix material comprises the following components in parts by weight: 32.5 parts of cement, 17.5 parts of fly ash, 16 parts of water, 15 parts of quartz sand and 0.1 part of water reducing agent.
Step three: the weighed materials are sequentially placed in a stirrer and fully stirred.
Step four: the material after thorough stirring was placed in a mould, demoulded after 24 hours and then stored in a standard curing chamber (20 ± 2 ℃ and 95% relative humidity) for 7 days.
Step five: the ordinary cement-based composite material after being cured for 7 days is subjected to prepressing treatment through a splitting tensile strength test, so that cracks are generated, and then the treated sample is placed in deionized water (20 +/-2 ℃) to test the compressive strength recovery rate and the porosity after 28 days, as shown in table 1.
Comparative example 1
A preparation method of a common cement-based composite material comprises the following steps:
the method comprises the following steps: weighing a cement base material, wherein the cement base material comprises the following components in parts by mass: 32.5 parts of cement, 17.5 parts of fly ash, 16 parts of water, 17.5 parts of quartz sand and 0.1 part of water reducing agent.
Step two: the weighed materials are sequentially placed in a stirrer and fully stirred.
Step three: the material after thorough stirring was placed in a mould, demoulded after 24 hours and then stored in a standard curing chamber (20 ± 2 ℃ and 95% relative humidity) for 7 days.
Step four: the ordinary cement-based composite material after being cured for 7 days is subjected to prepressing treatment through a splitting tensile strength test, so that cracks are generated, then a treated sample is placed in deionized water (20 +/-2 ℃), and the area restoration rate and the relative permeability coefficient after 28 days are tested, and are shown in table 1.
TABLE 1 Properties of the products
Compared with the comparative example 1, the embodiment 2 has the advantages that the self-repairing efficiency is improved by adding the self-repairing particles; example 2 as compared to example 1, it can be seen that the cracks can heal faster than the deionized water when cured in seawater; compared with the example 2, the self-repairing efficiency of the self-repairing particles is not much different when the particle size of the self-repairing particles is 1-2mm and 2-4 mm; compared with the example 3, the self-repairing particles with high carbon source content have better self-healing efficiency in the example 4; compared with example 4, the self-repairing cement-based composite material added with the permeable crystallization additive has the advantage that the self-repairing efficiency is obviously improved under the coupling effect of the self-repairing particles and the permeable crystallization additive in example 5.
Through the self-repairing particles with different particle sizes prepared in the examples 2 and 3, the self-repairing particles can be seen to be in a core-shell structure through the condition of the section, the outer part of the self-repairing particles is a hard shell, and the inner part of the self-repairing particles is a relatively soft self-repairing component.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A self-healing particle, comprising: comprises an inner core, a waterproof layer and an outer shell; the waterproof layer is a resin film and is coated on the outer surface of the inner core material; the shell is a cement shell;
the inner core comprises the following components in parts by mass: 5 to 7 parts of sodium carbonate, 1 to 3 parts of silica fume, 1 to 3 parts of silicon dioxide, 5 to 7 parts of quicklime, 1 to 2 parts of magnesia expanding agent and 1 to 2 parts of bentonite.
2. The self-healing particle of claim 1, wherein: the waterproof layer is made of epoxy resin.
3. The self-healing particle of claim 1, wherein: the cement shell is made of portland cement or sulphoaluminate cement.
4. The self-healing particle of claim 1, wherein: the particle size of the self-repairing particles is 1-5mm;
preferably, when the particle size of the self-repairing particles is 1-2mm, the thickness of the waterproof layer is 0.1-0.2mm, and the thickness of the cement shell is 0.2-0.4mm;
when the particle size of the self-repairing particles is 2-4mm, the thickness of the waterproof layer is 0.1-0.3mm, and the thickness of the cement shell is 0.2-0.5mm.
5. A method of making the self-healing particles of any one of claims 1 to 4, comprising: the method comprises the following steps:
putting sodium carbonate, silica fume, silicon dioxide, quicklime, a magnesium oxide expanding agent and bentonite into a granulator according to a certain proportion, spraying water for granulation, and drying granules to obtain an inner core;
coating the resin on the surface of the inner core to form a waterproof layer;
and finally, uniformly adhering cement powder on the surface of the waterproof layer to form a shell, thus obtaining the waterproof paint.
6. The method of making self-healing particles of claim 5, wherein: the method for coating the resin on the surface of the inner core specifically comprises the following steps:
putting the inner core into the mixed solution of the resin and the curing agent, stirring to ensure that the surface of the inner core is completely coated by the resin, then fishing out the inner core, and draining off the redundant resin;
the method for adhering the cement powder comprises the following steps:
spreading the filtered inner core wrapped with the resin layer in cement powder, and rolling to adhere the cement powder on the outer surface of the inner core; and screening out excessive cement powder, and curing.
7. A self-repairing cement-based composite material based on self-repairing particles is characterized in that: comprises 30-40 parts of cement matrix material and 1-3 parts of self-repairing material by weight, wherein,
the self-repairing material comprises the self-repairing particles and the permeable crystallization additive of any one of claims 1 to 4, wherein the mass ratio of the self-repairing particles to the permeable crystallization additive is 4-6.
8. The self-healing particle-based self-healing cement-based composite material of claim 7, wherein: the cement matrix material comprises the following components in parts by weight:
120 to 140 portions of Portland cement, 60 to 80 portions of fly ash, 60 to 70 portions of quartz sand, 60 to 90 portions of water and 1 to 2 portions of water reducing agent;
preferably, the cement matrix material consists of the following components in parts by weight: 125-135 parts of portland cement, 65-75 parts of fly ash, 60-65 parts of quartz sand, 70-80 parts of water and 1-1.5 parts of a water reducing agent;
preferably, the particle size of the quartz sand is 80-120 meshes.
9. The self-healing particle-based, self-healing cement-based composite material of claim 7, wherein: the mass ratio of the cement matrix material to the self-repairing material is 34-36;
preferably, the mass percentage of the self-repairing particles in the self-repairing material is 55-70%.
10. The preparation method of the self-repairing cement-based composite material of any one of claims 7 to 9, which is characterized in that: the method comprises the following steps: fully mixing the portland cement, the fly ash, the quartz sand and the self-healing particles;
and then adding a permeable crystallization additive, a water reducing agent and water into the mixture, and fully stirring to obtain the water reducing agent.
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