CN115536329B - 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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- CN115536329B CN115536329B CN202211077758.6A CN202211077758A CN115536329B CN 115536329 B CN115536329 B CN 115536329B CN 202211077758 A CN202211077758 A CN 202211077758A CN 115536329 B CN115536329 B CN 115536329B
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- 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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- 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
- 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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- 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
- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention discloses self-repairing particles, a self-repairing cement-based composite material and a preparation method thereof, wherein the self-repairing particles comprise 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 magnesium oxide expanding agent and 1 to 2 parts of bentonite. When the self-repairing particles are broken under the tip stress, the repairing agent in the self-repairing particles can be gradually dissolved in water to generate carbonate ions serving as repairing substances, and the carbonate ions are compounded with calcium ions in the cement matrix material to form calcium carbonate precipitates, so that the calcium carbonate precipitates are filled into micro-cracks to repair. The waterproof layer on the outer layer of the inner core material can reduce the water absorption rate of the self-repairing particles, prevent the water from entering in advance, prevent the repairing agent from reacting with substances in the cement matrix in advance, and ensure that the repairing agent plays a role after microcracks appear.
Description
Technical Field
The invention belongs to the technical field of building materials, and relates to self-repairing particles, 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 currently widely applied to the civil engineering industry. However, since the tensile strength of concrete is far lower than the compressive strength thereof, cracks are easily generated during the use process, particularly under the condition of external load, thereby influencing the bearing capacity, durability and safety of the whole structure.
The related technologies of cement-based material self-repairing mainly comprise microcapsule self-repairing, mineral cement-based self-repairing, electrochemical deposition self-repairing, shape memory alloy self-repairing, microorganism self-repairing and the like. However, each repair technology has limitations at present, and further optimization space exists, for example, the manufacturing process of microcapsule materials is complex and the price is high; the electrochemical deposition and the self-repairing of the shape memory alloy have special repairing conditions, and are difficult to apply to practical engineering; the microorganism is difficult to ensure long-term activity in concrete, and the repairing effect is not obvious.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide self-repairing particles, self-repairing cement-based composite materials and a preparation method thereof. The invention is based on microcapsule, mineral and osmotic crystallization self-repairing principle, and utilizes the influence of self-repairing particles and osmotic crystallization coupling effect on the self-healing performance of cement-based materials, so that the composite material can repair cracks in and on the surface of concrete more effectively.
In order to achieve the above object, the present 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 magnesium oxide expanding agent and 1 to 2 parts of bentonite.
In a second aspect, the present invention provides a method for preparing the self-healing particle, comprising the steps of:
putting sodium carbonate, silica fume, silicon dioxide, quicklime, magnesium oxide expanding agent and bentonite in proportion into a granulator, spraying water for granulation, and drying the granules to obtain an inner core;
wrapping 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.
In a third aspect, the invention provides a self-repairing cement-based composite material based on self-repairing particles, comprising, by weight, 30-40 parts of a cement matrix material and 1-3 parts of a self-repairing material, wherein,
the self-repairing material comprises the self-repairing particles and the penetrating crystallization additive, wherein the mass ratio of the self-repairing particles to the penetrating crystallization additive is 55-70:30-40.
In a fourth aspect, the method for preparing the self-repairing cement-based composite material comprises the following steps: fully mixing silicate cement, fly ash, quartz sand and self-healing particles;
and then adding the infiltration crystallization additive, the water reducer and water into the mixture, and fully stirring to obtain the water-soluble polymer.
The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:
(1) According to the self-repairing particle, the epoxy resin is used as a waterproof layer to wrap the active ingredients of the self-repairing particle, so that the entry of water molecules is prevented, the premature reaction of the self-repairing particle is avoided, and the self-repairing effect is lost.
The outermost layer is wrapped with 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 failed too early 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 in the cement-based material, and the weak surface in the interface transition area of the self-repairing particles and the cement matrix is avoided. The self-repairing particles can replace part of fine aggregate to be added into cement mortar.
The self-repairing particles have low strength of the inner core part, most self-repairing particles can be cracked from the middle after the cement mortar matrix is cracked, and the cracking can ensure that the internal repairing substances are separated out in water so as to repair the cracks.
The self-healing particles can heal cracks with the maximum diameter of about 1mm, the repairing time is short, the self-healing can be realized under the water curing condition without additional external conditions, the main healing products of the cracks are calcite precipitates, and the self-healing particles also comprise C-S-H gel and other self-healing products.
The self-repairing cement-based composite material is cured in seawater, the area repairing rate is rapidly improved in early stage, and the final area repairing rate is higher. It is important to have a greater healing speed for cracks in marine engineering, preventing further erosion.
The self-repairing particles and the osmotic crystallization additive provided by the invention have the advantages that the compressive strength recovery rate of the material is obviously improved and the relative osmotic coefficient of the material is obviously reduced compared with single self-repairing components under the coupling action of a certain proportion.
The self-repairing particles provided by the invention can repair macroscopic cracks of the material, the added penetrating crystallization master batch repairs micro cracks in the material, and under the coupling effect of the self-repairing particles and the penetrating crystallization master batch, self-healing at macroscopic and microscopic angles is realized, so that the self-healing efficiency of the cement-based material is greatly promoted.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 shows the structure of the self-repairing particles of different sizes prepared in examples 2 and 3 of the present invention.
FIG. 2 is a graph of the fracture surface of the self-repairing cement-based material prepared in example 2 (a) and example 3 (b) of the present invention.
Fig. 3 is a graph showing the comparison of the crack self-repairing effect before and after the self-repairing cement-based materials prepared in examples 1, 2, 3 and 4 according to the present invention, wherein (a) is the crack repairing effect of example 1, (b) is the crack repairing effect of example 2, (c) is the crack repairing effect of example 3, and (d) is the crack repairing effect of example 4.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. 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 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 magnesium oxide 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 the tip stress, the repairing agent in the self-repairing particles can be gradually dissolved in water to generate carbonate ions serving as repairing substances, and the carbonate ions are compounded with calcium ions in the cement matrix material to form calcium carbonate precipitates, so that the calcium carbonate precipitates are filled into micro-cracks 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, prevent moisture from entering in advance, prevent the repairing agent from reacting with substances in the cement matrix in advance, and ensure that the repairing agent plays a role after microcrack appears, thereby ensuring the long-term effectiveness of the repairing effect. In addition, compared with the self-repairing of microorganisms, the self-repairing particles have long-term activity and are more beneficial to repairing cracks in concrete.
The outermost layer of the self-repairing particles is a cement shell, has certain hardness, can improve the strength of the self-repairing particles, has good compatibility with cement-based materials, can keep integrity when being mixed with cement mortar mixture, and can prevent the self-repairing particles from being damaged and failed prematurely in the process of preparing the self-repairing cement-based composite materials.
The shell of the self-repairing particle is made of cement, and in the cement mortar hydration process, the shell of the self-repairing particle and the cement cementing material in the mortar can be hydrated simultaneously, so that the self-repairing particle and the cement-based material have good compatibility, and the occurrence of a weak surface in the interface transition area of the self-repairing particle and the cement matrix is avoided. The self-repairing particles can replace part of fine aggregate to be added into cement mortar.
The higher the content of the self-repairing granular carbon source, the better the self-healing efficiency. The cement matrix can separate out calcium hydroxide to supplement a calcium source, and carbonate generated by water dissolved in carbon dioxide in the air is relatively less, so that the difference of the carbonate in the self-repairing particles can not be completely compensated; compared with the sample with cracks generated by deionized water, the area repair rate is rapidly improved in early stage and the final area repair rate is higher. This is due to the efficiency and rate at which binding of ions in seawater can promote self-healing. The method has important significance for healing cracks faster and preventing further corrosion in ocean engineering.
The functions of the components in the inner core material are as follows:
sodium carbonate: the cement-based material may precipitate calcium hydroxide in water. Sodium carbonate is soluble in water and reacts with calcium ions to form calcium carbonate to fill the cracks.
Silica fume, silica: silica fume and nano-silica can provide highly reactive silica and react with calcium hydroxide to form hydrated calcium acid gel (C-S-H), can fill cracks, and improves cohesion between repair products.
Quicklime: the quick lime can provide calcium and alkaline environment to capture carbon dioxide to generate carbonate ions, so that the self-repairing is better realized by improving the amount of crack repairing products.
Magnesium oxide expanding agent, bentonite: the magnesium oxide expanding agent and bentonite have water expansion property, and after the inner core material of the self-healing particles is dissolved in water, the self-healing particles can expand and fill the remained holes, so that the generation of holes in the cement base is avoided, and the cement strength is reduced.
In some embodiments, the waterproof layer is made of epoxy resin. The epoxy resin has the characteristic of good viscosity, can uniformly wrap the self-repairing particle inner core, and can also bond cement powder to generate an outer shell. Most importantly, the epoxy resin and the curing agent react and then are cured to form a waterproof layer, so that the waterproof layer has good waterproof effect.
In some embodiments, the cement sheath is made of silicate cement or sulphoaluminate cement.
In some embodiments, the self-healing particles have a particle size of 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.
The self-repairing particles with two different particle sizes are respectively 1-2mm and 2-4mm, the self-repairing particles with the same mass have large specific surface area, more specific weight of cement shells and reduced repairing component ratio, but the self-repairing particles have no obvious difference on the area repairing rate. The particle size of 2-4mm has a 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, can be uniformly dispersed in cement mortar, and can be uniformly distributed at the crack position when the crack is generated. The interaction of the two particle size advantages and disadvantages results in the particle size of the self-healing particles having no significant effect on the self-healing efficiency.
In a second aspect, the present invention provides a method for preparing the self-healing particle, comprising the steps of:
putting sodium carbonate, silica fume, silicon dioxide, quicklime, magnesium oxide expanding agent and bentonite in proportion into a granulator, spraying water for granulation, and drying the granules to obtain an inner core;
wrapping 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.
The self-repairing granule inner core material has no reaction among substances in the granulating process, ensures the functionality of the self-repairing granule, and can ensure that when cement generates cracks, sufficient repairing products can be generated to fill the microcracks through a series of physicochemical reactions.
In some embodiments, the method for coating the resin on the surface of the inner core is specifically:
and (3) placing the inner core into a mixed solution of resin and curing agent, stirring to completely coat the surface of the inner core with 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 coated with the resin layer into cement powder, and rolling to adhere the cement powder to the outer surface of the inner core; and (5) screening out excessive cement powder and solidifying.
The disc granulator is tilted at 45 deg. and rotated at 30r/min until the particle size in the disc is observed to reach the desired range, and the granulation time of the core material is about 5-10 min.
And (3) placing the prepared self-repairing granule inner cores in a drying oven at 40 ℃ for drying for 24 hours so as to ensure that the active ingredients in the self-repairing granule cannot react in advance, thereby ensuring the long-term effectiveness of the repairing effect.
And (3) placing the prepared self-repairing particles into a constant temperature and humidity box (the temperature is 50 ℃ and the relative humidity is 90%), and preserving for a period of time to obtain the self-repairing particles with certain hardness of the outer shell and soft inner core.
In a third aspect, the invention provides a self-repairing cement-based composite material based on self-repairing particles, comprising, by weight, 30-40 parts of a cement matrix material and 1-3 parts of a self-repairing material, wherein,
the self-repairing material comprises self-repairing particles and an osmotic crystallization additive, wherein the mass ratio of the self-repairing particles to the osmotic crystallization additive is 4-6:1-3.
The osmotic crystallization additive is crack self-healing cement-based osmotic crystallization active master batch produced by Prowa technology Co.
The osmotic crystallization additive is an active additive, and is a core additive specially used for producing cement-based osmotic crystallization type waterproof paint.
Self-repairing particles are divided into three types in cement mortar, namely cracking from the middle, cracking along a shell layer and non-cracking. For the self-repairing particles with three types and two particle sizes, because the strength of the inner core part of the self-repairing particles is low, most of the self-repairing particles can be cracked from the middle after the crack of the cement mortar matrix occurs, but not along the interface transition region of the self-repairing particles and the cement matrix, the crack can trigger the self-repairing particles to crack after the crack occurs, and the crack can ensure that the 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 reducer.
The fly ash (such as the I-class 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 consumption of cement is reduced, the cost is reduced, the environmental pollution is reduced, and the utilization of part of solid waste is realized.
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 reducer.
Each component in the cement matrix material forms a matrix structure of the self-repairing material. The self-repairing particle structure shell is a cement component, can be well combined with a cement matrix material, has good compatibility, and can not generate a weak surface at an interface, so that the improvement is ensured that the material strength is not greatly reduced, and the self-repairing particle structure shell is not damaged at the interface of the self-repairing particle and the cement matrix. The self-repairing particles can be uniformly dispersed in the matrix material, and the repairing effect is improved after the crack appears.
Preferably, the particle size of the quartz sand is 80-120 meshes.
In some embodiments, the mass ratio of cement matrix material to self-healing material is 34-36:1.2-1.6.
In some embodiments, the self-healing particles in the self-healing material are 55-70% by mass, such as may be 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%.
In some embodiments, the water reducing agent is a liquid polycarboxylic acid high efficiency water reducing agent.
In a fourth aspect, the method for preparing the self-repairing cement-based composite material comprises the following steps: fully mixing silicate cement, fly ash, quartz sand and self-healing particles;
and then adding the infiltration crystallization additive, the water reducer and water into the mixture, and fully stirring to obtain the water-soluble polymer.
The self-repairing particles are added first, so that the self-repairing particles can be uniformly distributed in cement, and then water and a water reducing agent are added, so that the self-repairing particles can be uniformly dispersed in the repairing cement-based composite material, and a good self-repairing function can be 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 small self-repairing particle content change can adopt self-repairing particles with equal mass to replace part of quartz sand.
After the sample is prepared, the sample is respectively placed in deionized water and seawater, and the environment under different water is simulated, so that the difference of the self-repairing efficiency of the cement-based composite material is simulated. The seawater is inSampling in coastal region of Qingdao, 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 invention is further illustrated below with reference to examples.
Example 1
The preparation method of the self-repairing cement-based composite material comprises the following steps:
step one: the preparation method of the self-repairing particles comprises the following steps:
(1) The self-repairing particle inner core material is weighed and 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) The prepared core material is put into a disc granulator, the inclination angle of the disc granulator is adjusted to 45 degrees, and the rotating speed is 30r/min.
(3) And spraying deionized water onto the mixed powder in batches, taking out and sieving after the particles are spherical, and placing the powder in a drying oven 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 according to the mass ratio of 1:1, 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, then taking out by a strainer, draining off the excessive epoxy resin, and forming a layer of transparent film on the surface of the inner core to form a waterproof layer.
(5) In order to prevent the mutual adhesion between the samples, the filtered samples are rapidly spread into ordinary Portland cement, and the samples are slightly rubbed in cement powder, so that the cement powder is uniformly adhered on the surfaces of the samples to form an outer protective shell. And finally, screening out excessive cement powder by using a screen, screening out self-healing particles with the particle size of 1-2mm, and preserving for standby after the epoxy resin is completely solidified.
Step two: weighing self-repairing cement matrix material, which 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 reducer.
Step three: the weighed materials are placed in a stirrer in sequence and fully stirred.
Step four: the well-stirred material was placed in a mold, demolded 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 curing for 7 days was subjected to pre-pressing treatment by a split tensile strength test to thereby generate cracks, and then the treated sample was placed in seawater (20.+ -. 2 ℃ C.) to test its area repair rate and relative permeability coefficient after 28 days, as shown in Table 1.
Example 2
The preparation method of the self-repairing cement-based composite material comprises the following steps:
step one: self-healing particles were prepared according to the preparation method of example 1, step one.
Step two: weighing self-repairing cement matrix material, which 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 reducer.
Step three: the weighed materials are placed in a stirrer in sequence and fully stirred.
Step four: the well-stirred material was placed in a mold, demolded 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 curing for 7 days was subjected to pre-pressing treatment through a split tensile strength test to generate cracks, and then the treated sample was placed in deionized water (20.+ -. 2 ℃ C.) to test the area repair rate and relative permeability coefficient after 28 days, as shown in Table 1.
Example 3
The preparation method of the self-repairing cement-based composite material comprises the following steps:
step one: the preparation method of the self-repairing particles comprises the following steps:
(1) The self-repairing particle inner core material is weighed and 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) The prepared core material is put into a disc granulator, the inclination angle of the disc granulator is adjusted to 45 degrees, and the rotating speed is 30r/min.
(3) And spraying deionized water onto the mixed powder in batches, taking out and sieving after the particles are spherical, and placing the powder in a drying oven 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 ensure that the surface of the inner core is completely coated by the epoxy resin, then taking out by using a strainer, draining off the excessive epoxy resin, and forming a layer of transparent film on the surface of the inner core to form a waterproof layer.
(5) In order to prevent the mutual adhesion between the samples, the filtered samples are rapidly spread into ordinary Portland cement, and the samples are slightly rubbed in cement powder, so that the cement powder is uniformly adhered on the surfaces of the samples to form an outer protective shell. And finally, screening out excessive cement powder by using a screen, screening out self-healing particles with the particle size of 2-4mm, and preserving for standby after the epoxy resin is completely solidified.
Step two: weighing self-repairing cement matrix material, which 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 reducer.
Step three: the weighed materials are placed in a stirrer in sequence and fully stirred.
Step four: the well-stirred material was placed in a mold, demolded 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 curing for 7 days was subjected to pre-pressing treatment through a split tensile strength test to generate cracks, and then the treated sample was placed in deionized water (20.+ -. 2 ℃ C.) to test the area repair rate and 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
The preparation method of the self-repairing cement-based composite material comprises the following steps:
step one: the preparation method of the self-repairing particles comprises the following steps:
(1) The self-repairing particle inner core material is weighed and 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) The prepared core material is put into a disc granulator, the inclination angle of the disc granulator is adjusted to 45 degrees, and the rotating speed is 30r/min.
(3) And spraying deionized water onto the mixed powder in batches, taking out and sieving after the particles are spherical, and placing the powder in a drying oven 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 ensure that the surface of the inner core is completely coated by the epoxy resin, then taking out by using a strainer, draining off the excessive epoxy resin, and forming a layer of transparent film on the surface of the inner core to form a waterproof layer.
(5) In order to prevent the mutual adhesion between the samples, the filtered samples are rapidly spread into ordinary Portland cement, and the samples are slightly rubbed in cement powder, so that the cement powder is uniformly adhered on the surfaces of the samples to form an outer protective shell. And finally, screening out excessive cement powder by using a screen, screening out self-healing particles with the particle size of 2-4mm, and preserving for standby after the epoxy resin is completely solidified.
Step two: weighing self-repairing cement matrix material, which 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 reducer.
Step three: the weighed materials are placed in a stirrer in sequence and fully stirred.
Step four: the well-stirred material was placed in a mold, demolded 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 curing for 7 days was subjected to pre-pressing treatment through a split tensile strength test to generate cracks, and then the treated sample was placed in deionized water (20±2 ℃) to test the area restoration rate, the relative permeability coefficient, the compressive strength restoration rate and the porosity after 28 days, as shown in table 1.
As can be seen from fig. 2, the fracture interface of the self-repairing cement-based material contains a plurality of self-repairing particles inside, the self-repairing particles inside are dispersed uniformly, and the majority of the self-repairing particles on the fracture surface are cracked from the middle and along the shell layer, so that the self-repairing components can be effectively released.
In fig. 3, the top is a fracture map of the self-repairing cement-based material, and the bottom is a map after repair, and it can be seen that the crack is substantially healed after repair for a certain period of time, as compared before and after repair.
Example 5
The preparation method of the self-repairing cement-based composite material comprises the following steps:
step one: self-healing particles were prepared according to the preparation method of example 4, step one.
Step two: weighing self-repairing cement matrix material, which 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 osmotic 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 reducer.
Step three: the weighed materials are placed in a stirrer in sequence and fully stirred.
Step four: the well-stirred material was placed in a mold, demolded 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 curing for 7 days was subjected to a pre-pressing treatment by a split tensile strength test to thereby generate cracks, and then the treated sample was placed in deionized water (20.+ -. 2 ℃ C.) to test the compressive strength recovery rate and 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:
step one: weighing a cement matrix material, wherein the cement matrix 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 reducer.
Step two: the weighed materials are placed in a stirrer in sequence and fully stirred.
Step three: the well-stirred material was placed in a mold, demolded 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 curing for 7 days was subjected to pre-pressing treatment through a split tensile strength test to generate cracks, and then the treated sample was placed in deionized water (20.+ -. 2 ℃ C.) to test the area repair rate and relative permeability coefficient after 28 days, as shown in Table 1.
TABLE 1 product Properties
Example 2 shows that the addition of the self-healing particles improves the self-healing efficiency compared to comparative example 1; example 2 shows that compared to example 1, the crack heals faster when maintained in seawater than deionized water; example 3 shows that the self-repairing efficiency is not much different from that of example 2 when the particle size of the self-repairing particles is 1-2mm and 2-4 mm; example 4 shows that the self-healing particles with high carbon source content have better self-healing efficiency compared with example 3; example 5 compared with example 4, it is clear that the self-repairing cement-based composite material added with the penetrating crystallization additive has obviously improved self-repairing efficiency under the coupling action of the self-repairing particles and the penetrating crystallization additive.
The self-healing particles of different particle sizes prepared by examples 2 and 3, by section, can be seen to be core-shell structure, outer hard shell, and inner relatively soft self-healing composition.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A self-healing particle, characterized in that: 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: 5-7 parts of sodium carbonate, 1-3 parts of silica fume, 1-3 parts of silicon dioxide, 5-7 parts of quicklime, 1-2 parts of magnesium oxide expanding agent and 1-2 parts of bentonite;
the preparation method comprises the following steps:
putting sodium carbonate, silica fume, silicon dioxide, quicklime, magnesium oxide expanding agent and bentonite in proportion into a granulator, spraying water for granulation, and drying the granules to obtain an inner core;
wrapping resin on the surface of the inner core to form a waterproof layer;
finally, uniformly adhering cement powder on the surface of the waterproof layer to form a shell, thus obtaining the waterproof layer;
the waterproof layer is made of epoxy resin;
the cement shell is made of silicate cement or sulphoaluminate cement.
2. The self-healing particle of claim 1, wherein: the particle size of the self-repairing particles is 1-5mm;
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.
3. The self-healing particle according to any one of claims 1 to 2, wherein: in the preparation method, the method for wrapping the resin on the surface of the inner core comprises the following steps:
placing the inner core into a mixed solution of resin and curing agent, stirring to completely coat the surface of the inner core with the resin, fishing out the inner core, and draining off excessive resin;
the method for adhering the cement powder comprises the following steps:
spreading the filtered inner core coated with the resin layer into cement powder, and rolling to adhere the cement powder to the outer surface of the inner core; and (5) screening out excessive cement powder and solidifying.
4. A self-healing cement-based composite based on self-healing particles, characterized in that: comprises 30-40 parts of cement matrix material and 1-3 parts of self-repairing material by weight,
the self-repairing material comprises the self-repairing particles and the penetrating crystallization additive according to any one of claims 1 to 3, wherein the mass ratio of the self-repairing particles to the penetrating crystallization additive is 4-6:1-3;
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 reducer;
the particle size of the quartz sand is 80-120 meshes.
5. The self-healing cement-based composite based on self-healing particles according to claim 4, wherein:
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 reducer.
6. The self-healing cement-based composite based on self-healing particles according to claim 4, wherein: the mass ratio of the cement matrix material to the self-repairing material is 34-36:1.2-1.6;
7. the self-healing cement-based composite based on self-healing particles according to claim 4, wherein: the mass percentage of the self-repairing particles in the self-repairing material is 55-70%.
8. A method of making the self-healing cementitious composite of any one of claims 4-7, comprising: the method comprises the following steps: fully mixing silicate cement, fly ash, quartz sand and self-repairing particles;
and then adding the infiltration crystallization additive, the water reducer and water into the mixture, and fully stirring to obtain the water-soluble polymer.
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