CN111253130A - High-strength heat-resistant self-repairing concrete and preparation method thereof - Google Patents
High-strength heat-resistant self-repairing concrete 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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- 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
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/04—Heat treatment
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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
- C04B2111/00017—Aspects relating to the protection of the environment
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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
- C04B2111/34—Non-shrinking or non-cracking materials
- C04B2111/343—Crack resistant 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
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
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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
Abstract
The invention discloses a high-strength heat-resistant self-repairing concrete and a preparation method thereof, wherein the concrete comprises the following components in parts by weight: 360 parts of 340-grade cement, 160 parts of 140-grade fly ash, 800 parts of 750-grade broken stone, 750 parts of 730-grade medium sand, 120 parts of 110-grade coarse aggregate, 1-5 parts of water reducing agent, 180 parts of 170-grade water, 1-5 parts of polypropylene fiber, 50-80 parts of mineral powder, 1-5 parts of early strength agent, 20-30 parts of composite fiber and 5-10 parts of self-repairing material; the coarse aggregate is formed by mixing hollow glass microspheres and ceramsite in a mass ratio of 1: 1.2-1.5; the composite fiber comprises 5-10 parts of aramid fiber, 3-6 parts of glass fiber, 5-10 parts of resorcinol-formaldehyde resin and 0.3-1.4 parts of copolyoxymethylene; the self-repairing material comprises 6-8 parts of cement and 2-4 parts of diluted epoxy resin; the self-repairing material further comprises 0.5-1 part of calcined tuff and 0.5-1 part of carbon nano tubes; the high-strength heat-resistant concrete provided by the invention has high strength and good heat resistance, and can realize self-repair when a wall body is damaged and cracked.
Description
Technical Field
The invention relates to the technical field of concrete, in particular to concrete which is high in strength and good in heat resistance and can realize self-repair when a wall body is damaged and cracked and a preparation method thereof.
Background
The heat-resistant concrete is special concrete which can still maintain the physical and mechanical properties and good rapid cooling and heat resistance under the long-term action of high temperature of 200-1300 ℃ and has small shrinkage deformation at high temperature, and is widely applied to the reconstruction and overhaul projects of the iron-making blast furnace.
In the prior art, reference is made to a Chinese patent with an authorization publication number of CN105272020B, which discloses C40 pump concrete with the heat resistance of 500 ℃, and the single-component dosage ratio (kg/m 3) of the concrete is as follows: 200-220 cement, 80-100 fly ash, 100-120 slag micro powder, 420-460 natural medium sand with the fineness modulus of 1.8-2.0, 400 andesite machine-made sand, 980-1000 andesite continuous graded crushed stones with the thickness of 5-20mm, 4.00-4.80 admixture, 165-170 blending water and 0.9 polypropylene fiber.
The strength grade of the C40 pump concrete with the heat resistance of 500 ℃ is C40, the heat resistance temperature is 500 ℃, for some buildings with higher strength requirements, high-strength concrete is required to be used, the high-strength concrete refers to C60 and the concrete above the C60 and is called high-strength concrete, and the high-strength concrete is used as a new building material and is widely applied to high-rise building structures, large-span bridge structures and certain special structures due to the superiorities of high compressive strength, strong deformation resistance, large density and low porosity; the high-strength concrete has the greatest characteristic of high compressive strength which is generally 4-6 times of that of common strength concrete, so that the cross section of a member can be reduced, and the high-strength concrete is most suitable for high-rise buildings; however, the existing heat-resistant concrete can only reach the compressive strength of C30-C40 and can not meet the requirement of high-strength concrete, so how to enable the concrete to have high strength while obtaining heat resistance is a problem to be solved.
On the other hand, concrete is a porous brittle material, but during the use process, due to the influence of adverse factors such as fatigue effect, corrosion effect and aging, the concrete structure generates damage accumulation and resistance attenuation, so that micro cracks and local damage are inevitably generated, and the crack leakage generated by the structure under the action of vibration load, water loss drying shrinkage, settlement and corrosive media is unpredictable, and the anti-permeability performance and the service life of the concrete are seriously influenced. When the concrete generates micro cracks or partial damage, the original waterproof and anti-permeability capability is lost.
China has abundant tuff resources, the tuff has certain volcanic ash activity, and active silicon oxide, active aluminum oxide and calcium hydroxide react to generate calcium aluminosilicate hydrate with gel property. The water content of the tuff raw ore obtained by mining and crushing is too high, the tuff raw ore cannot reach the optimal use state in industrial application, and in addition, a large amount of stone powder is generated in the tuff production process and is not effectively utilized, so that the resource waste is caused. In order to improve the utilization efficiency of energy resources, the pollution prevention and control capability and the ecological environment quality in the building industry, the comprehensive utilization technology of tuff is further explored, the effects of saving resources, saving energy and reducing emission can be achieved, and the method has obvious economic benefits and social benefits.
Disclosure of Invention
The invention aims to provide high-strength heat-resistant self-repairing concrete which has high strength and good heat resistance and can realize self-repairing when a wall body is damaged and cracked, and a preparation method thereof, so as to solve the problems in the background technology.
The technical scheme of the invention is as follows:
in order to achieve the purpose, the invention provides the following technical scheme: the high-strength heat-resistant self-repairing concrete comprises the following components in parts by weight: 360 parts of 340-grade cement, 160 parts of 140-grade fly ash, 800 parts of 750-grade broken stone, 750 parts of 730-grade medium sand, 120 parts of 110-grade coarse aggregate, 1-5 parts of water reducing agent, 180 parts of 170-grade water, 1-5 parts of polypropylene fiber, 50-80 parts of mineral powder, 1-5 parts of early strength agent, 20-30 parts of composite fiber and 5-10 parts of self-repairing material;
the coarse aggregate is formed by mixing hollow glass microspheres and ceramsite in a mass ratio of 1: 1.2-1.5;
the composite fiber comprises 5-10 parts of aramid fiber, 3-6 parts of glass fiber, 5-10 parts of resorcinol-formaldehyde resin and 0.3-1.4 parts of copolymethylene;
the self-repairing material comprises 6-8 parts of cement and 2-4 parts of diluted epoxy resin.
The composite fiber is prepared by the following method: (1) stirring resorcinol-formaldehyde resin at 99-109 deg.C, melting, adding aramid fiber and glass fiber, curing at room temperature for 6-8 hr, and pulverizing into particles with average particle diameter of 10-20 mm;
(2) melting the copolyformaldehyde at 180-200 ℃, carrying out ultrasonic treatment on the product obtained in the step (1), wherein the ultrasonic frequency is 23-25kHz, the time is 5-10min, adding the product into the copolyformaldehyde, uniformly mixing, drying at 80-90 ℃, and crushing the dried product into powder with the particle size of 1-5 mm.
Preferably, the self-repairing material further comprises 0.5-1 part of calcined tuff and 0.5-1 part of carbon nanotubes. The calcined tuff is acid tuff, and is prepared by grinding tuff, sieving with a 200-mesh sieve, preheating with microwave at 600 ℃ for 10-30min under 300-plus temperature, calcining at 1100 ℃ for 0.5-1 h under 900-plus temperature, and cooling.
The preparation method of the self-repairing material comprises the steps of mixing and stirring cement, diluted epoxy resin, calcined tuff and carbon nano tubes which are weighed according to the formula ratio for 5-10min to form a viscous liquid state, extruding the viscous liquid state into blocks by an extruding machine or a briquetting machine, and crushing the viscous liquid state into particles with the diameter of 30-50 mm by a crusher.
Preferably, the resorcinol-formaldehyde resin is prepared by reacting resorcinol and formaldehyde in a mass ratio of 1:0.6-0.7 at the temperature of 100-150 ℃ and cooling; the length of the aramid fiber is 1-3mm, and the length of the glass fiber is 3-9 mm; the particle size of the hollow glass beads is 10-15mm, and the particle size of the ceramsite is 5-10 mm; the fly ash is F-class II-grade fly ash, the fly ash is low-calcium II-grade fly ash, the fineness (the screen residue of a 45-micrometer square-hole screen) is 8-12%, the water demand ratio is 95-98%, and the loss on ignition is 2-4.5%.
Preferably, the water reducing agent is one of an aliphatic (hydroxy) sulfonate high-efficiency water reducing agent, a naphthalene high-efficiency water reducing agent and a polycarboxylic acid high-efficiency water reducing agent; the fineness modulus of the medium sand is 2.3-3.0, the mud content is 2-2.6%, and the mud block content is 0.45-0.65%; the mineral powder is S95 grade mineral powder, the activity index in 28 days is 95%, and the fluidity ratio is 99%.
The preparation method of the high-strength heat-resistant self-repairing concrete comprises the following steps:
s1: quantitative weighing, namely weighing all the raw materials according to the components;
s2: fully and uniformly mixing cement, fly ash, broken stone, medium sand, mineral powder and coarse aggregate to prepare a premix;
s3: adding a water reducing agent, an early strength agent, polypropylene fibers and composite fibers into water, uniformly mixing, adding the mixture into a premix, fully mixing for 80-120min, then adding the prepared self-repairing material, fully mixing and uniformly shaking to prepare the high-strength heat-resistant self-repairing concrete.
The invention has the following beneficial effects:
compared with the prior art, the invention has the beneficial effects of high strength, heat resistance and self-repairing:
1. according to the invention, the aramid fiber and the glass fiber are blended to prepare the composite fiber, the excellent mechanical property of the glass fiber can make up the problem that the hydrogen bond between molecular chains is weak due to the fact that the aramid fiber contains a large amount of aromatic rings in molecules, and the composite fiber has excellent mechanical property, so that the concrete has higher compressive strength and heat resistance.
2. According to the invention, resorcinol-formaldehyde resin, aramid fiber and glass fiber are preferably adopted to prepare the heat-resistant fiber material, and due to the fact that the aramid fiber is lack of chemical active groups, the surface of the aramid fiber is poor in wettability and cohesiveness, the tensile strength of the aramid fiber can be improved, the cohesive force of the composite fiber is improved, and therefore, cracks of concrete at high temperature are prevented, and the heat resistance of the concrete is improved. In addition, the aramid fiber and the glass fiber are treated by the microwave, so that the bonding performance among the aramid fiber, the glass fiber and the resorcinol-formaldehyde resin in the composite fiber can be improved, the resorcinol-formaldehyde resin can fully and uniformly infiltrate the aramid fiber and the glass fiber, and the bonding performance of the composite fiber is improved.
3. The self-repairing material added in the invention mainly uses cement and diluted epoxy resin. Unlike common epoxy resin as cementing material in concrete preparation, the diluted epoxy resin is not enough to be used as cementing material but as adhesive for dry cement, and is used for pure cement molding and caking. The self-repairing material is added when the premix, the additive and water are initially mixed for 80-120min and are in a semi-fluid state, and the mixture is fully mixed and vibrated for the second time, so that the self-repairing material is uniformly distributed in the concrete, the additive and the water are fully contacted with the premix, the self-repairing material does not absorb or only absorbs little free moisture, the self-repairing material hardly further reacts with other additives and water, and most of cement ingredients in the self-repairing material are kept in a dry state and a state of not generating the concrete. When the formed concrete is used for a long time and cracks are broken, water permeates from the broken cracks and reacts with unreacted cement locally, the coated diluted epoxy resin particles can be used as fine aggregates due to a small reaction range, and the cement and the water are mixed to become liquid and slowly fill the broken cracks and then are formed, so that the self-repairing effect of the concrete is achieved.
4. The self-repairing material comprises calcined tuff and carbon nanotubes. The calcined tuff expands due to the vitreous after calcination to form a loose and porous structure, and montmorillonite in the calcined tuff has a layered structure and can generate chemical adsorption and cation exchange effects until the self-repairing material is in a dormant state after the concrete is dried and molded. When micro cracks or pores appear in the formed concrete and water permeates into the formed concrete, the doped carbon nano tubes can enhance the siphonage generated by crack fracture surfaces to introduce water into the self-repairing material uniformly existing in the concrete, the calcined tuff releases active substances after absorbing water, and Ca (OH) is provided for unhydrated cement2Calcination of tuff in alkaline environment provides highly active SiO2And Al2O3The chemical conversion is carried out, so that more stable CaSiO3 crystals, needle-shaped ettringite crystals and other filling pores are generated, the pores are blocked and cracks are filled, and the self-repairing of concrete cracks is realized; the cement is used as aggregate and catalyst in the formation of CaSiO3 crystalUnder the condition of the agent, the agent can react with the infiltrated water to form new concrete filling pores and cracks; other active groups in the self-repairing material are substituted to form new free radicals, and the new free radicals are captured by unreacted high-activity calcined tuff, and Ca (OH) is generated when water seepage occurs2When the concentration is high, the calcium ions are subjected to complexation and precipitation to fill pores and cracks. The components have synergistic effect, effectively complete the self-repairing process, further achieve the overall waterproof effect, and show good self-repairing capability.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The epoxy resin used in the following examples of the repair material was selected from E44 type epoxy resin produced by wuxi qian Guanghuazai Chemicals Co., Ltd, and tuff was selected from four-mountain stone fields in east town of Jinyun county.
Repair material 1: (1) epoxy resin E44 was diluted with benzyl alcohol and added in an amount of 80 phr. Adding 4kg of diluted epoxy resin heated to 40 ℃ into 8kg of cement, stirring for 5min, extruding into compact strips by an extruder, drying, and crushing into particles with the diameter of 30mm by a crusher.
Repairing material 2: (1) grinding the acid tuff powder, sieving with a 200-mesh sieve, preheating with microwave at 450 deg.C for 20min, calcining at 1000 deg.C for 1 hr, and cooling to obtain calcined tuff.
(2) Epoxy resin E44 was diluted with benzyl alcohol and added in an amount of 80 phr. Adding 2.5kg of diluted epoxy resin heated to 40 ℃ to 6kg of cement, adding 0.75kg of the calcined tuff prepared in the step (1) and 0.75kg of carbon nanotubes while stirring, stirring for 10min, compacting into compact strips by a briquetting machine, drying, and crushing into particles with the diameter of 40mm by a crusher.
Repairing material 3: (1) grinding the acid tuff powder, sieving with a 200-mesh sieve, preheating with microwave at 300 deg.C for 10min, calcining at 900 deg.C for 1 hr, and cooling to obtain calcined tuff.
(2) Epoxy resin E44 was diluted with benzyl alcohol and added in an amount of 80 phr. Adding 2kg of diluted epoxy resin heated to 40 ℃ into 7kg of cement, adding 0.5kg of the calcined tuff prepared in the step (1) and 0.5kg of carbon nanotubes while stirring, stirring for 5min, compacting into compact strip-shaped blocks by a briquetting machine, drying, and crushing into particles with the diameter of 50mm by a crusher.
Repairing material 4: (1) grinding the acid tuff powder, sieving with a 200-mesh sieve, preheating with microwave at 600 deg.C for 30min, calcining at 1100 deg.C for 0.5 hr, and cooling to obtain calcined tuff.
(2) Epoxy resin E44 was diluted with benzyl alcohol and added in an amount of 80 phr. Adding 2kg of diluted epoxy resin heated to 40 ℃ to 6kg of cement, adding 1kg of the calcined tuff prepared in the step (1) and 1kg of carbon nanotubes while stirring, stirring for 10min, extruding into compact strips by an extruder, drying, and crushing into particles with the diameter of 40mm by a crusher.
The following examples of composite fibers were prepared with polyoxymethylene selected from Shanyi plastication Co., Ltd, Dongguan, aramid fiber selected from Jiangxi Shuobang New Material science and technology Co., Ltd, and glass fiber selected from Hebeijing aviation mineral products Co., Ltd.
Composite fiber 1: (1) reacting resorcinol and formaldehyde in a mass ratio of 1:0.7 at 100 ℃, and cooling to obtain resorcinol-formaldehyde resin;
(2) stirring 5kg of resorcinol-formaldehyde resin at 95 ℃ until the resorcinol-formaldehyde resin is melted, adding 5kg of aramid fiber (length of 2mm) and 5kg of glass fiber (length of 6mm), curing at room temperature for 6h, and pulverizing into particles with average particle size of 10 mm;
(3) and (3) treating the particles in the step (2) for 5min by using ultrasonic waves with the frequency of 23kHz, adding the particles into 0.3kg of copolyoxyformaldehyde which is melted at 180 ℃, uniformly mixing, drying at 80 ℃, and crushing into powder with the particle size of 1mm after drying.
Composite fiber 2: (1) reacting resorcinol and formaldehyde in a mass ratio of 1:0.6 at 130 ℃, and cooling to obtain resorcinol-formaldehyde resin;
(2) stirring 7kg of resorcinol-formaldehyde resin at 100 ℃ until the resorcinol-formaldehyde resin is melted, adding 7kg of aramid fiber (length of 1mm) and 3kg of glass fiber (length of 3mm), curing at room temperature for 7h, and crushing into particles with average particle size of 15 mm;
(3) and (3) treating the particles in the step (2) for 5min by using ultrasonic waves with the frequency of 23kHz, adding the particles into 0.7kg of copolyoxyformaldehyde which is melted at 190 ℃, uniformly mixing, drying at 85 ℃, and crushing into powder with the particle size of 3mm after drying.
Composite fiber 3: (1) reacting resorcinol and formaldehyde in a mass ratio of 1:0.7 at 150 ℃, and cooling to obtain resorcinol-formaldehyde resin;
(2) stirring 10kg of resorcinol-formaldehyde resin at 105 deg.C to melt, adding 10kg of aramid fiber (length of 3mm) and 6kg of glass fiber (length of 9mm), curing at room temperature for 8 hr, and pulverizing into particles with average particle diameter of 20 mm;
(3) and (3) treating the particles in the step (2) for 10min by using ultrasonic waves with the frequency of 23kHz, adding the particles into 1.4kg of copolyoxyformaldehyde which is melted at the temperature of 200 ℃, uniformly mixing, drying at the temperature of 90 ℃, and crushing into powder with the particle size of 5mm after drying.
TABLE 1 ratio of different self-repairing material preparation examples to composite fiber preparation examples
In the following examples, the polycarboxylic acid superplasticizer is selected from Shanghai Shoorgao industries, Inc., the naphthalene series superplasticizer is selected from Luoyang Tongrun information technology Inc., the aliphatic (hydroxy) sulfonate superplasticizer is selected from Beijing Doudao building materials, Inc., and the early strength agent is selected from Jinan Yunze chemical Inc.
Table 2 materials and proportions of the materials used in the formulations of the different examples
Example 1:
s1: the cement is P.O42.5 Portland cement, the fly ash is low-calcium II-grade cement, the fineness (the sieve residue of a square-hole sieve with the size of 45 mu m) is 8 percent, the water demand ratio is 95 percent, the loss on ignition is 2 percent, the broken stone is continuous graded broken stone with the size of 5-20mm, the fineness modulus of the medium sand is 2.3, the mud content is 2 percent, the mud block content is 0.45 percent, the mineral powder is S95 grade mineral powder, the 28-day activity index is 95 percent, the fluidity ratio is 99 percent, the coarse aggregate is formed by mixing hollow glass microspheres and ceramsite with the mass ratio of 1:1.2, the particle size of the hollow glass microspheres is 10mm, and the particle size of the ceramsite is 5 mm.
S2: according to the raw material proportion in the table 2, the cement, the fly ash, the broken stone, the medium sand, the mineral powder and the coarse aggregate in the S1 are fully and uniformly mixed to prepare a premix A;
s3: according to the raw material proportion in the table 2, adding an aliphatic (hydroxy) sulfonate superplasticizer, an early strength agent, polypropylene fibers and composite fibers 1 into water, uniformly mixing, adding the obtained mixture into a premix A, fully mixing for 80min, adding the prepared self-repairing material 1, fully mixing and uniformly vibrating to obtain the high-strength heat-resistant self-repairing concrete.
Example 2 differs from example 1 in that: the fly ash is low-calcium II grade, the fineness (the screen allowance of a 45-micron square-hole screen) is 11%, the water demand ratio is 97%, the ignition loss is 3%, the fineness modulus of the medium sand is 2.7, the mud content is 2.3%, the mud block content is 0.55%, the coarse aggregate is formed by mixing hollow glass microspheres and ceramsite according to the mass ratio of 1:1.4, the particle size of the hollow glass microspheres is 13mm, and the particle size of the ceramsite is 8 mm. And S3, adding a polycarboxylic acid high-efficiency water reducing agent and a self-repairing material 2, adding the premix A, and fully mixing for 100 min.
Example 3 differs from example 1 in that: the fly ash is low-calcium II grade, the fineness (the screen allowance of a 45-micron square-hole screen) is 13%, the water demand ratio is 98%, the ignition loss is 4.5%, the fineness modulus of the medium sand is 3.0, the mud content is 2.6%, the mud block content is 0.65%, the coarse aggregate is formed by mixing hollow glass beads and ceramsite according to the mass ratio of 1:1.5, the particle size of the hollow glass beads is 15mm, and the particle size of the ceramsite is 10 mm. And (3) adding a naphthalene water reducer and a self-repairing material 3 into S3, and fully mixing for 120min after adding the premix A.
Example 4 differs from example 2 in that: in S3, composite fiber 2 and self-repairing material 3 are used.
Example 5 differs from example 2 in that: in S3, composite fibers 3 and a self-repairing material 4 are used.
Table 3 different comparison examples formula selected materials and proportion
Comparative example 1 differs from example 2 in that: coarse aggregate, polypropylene fiber, mineral powder, composite fiber and self-repairing material are not added in the formula.
Comparative example 2 differs from example 2 in that: the composite fiber is not added in the formula.
Comparative example 3 differs from example 2 in that: coarse aggregate, polypropylene fiber and mineral powder are not added in the formula.
Comparative example 4 differs from example 2 in that: coarse aggregate, polypropylene fiber, mineral powder and composite fiber are not added in the formula.
And (3) performance test aspects: high-strength heat-resistant concretes were prepared according to the methods of examples 1 to 5 and comparative examples 1 to 3, and the properties of the prepared high-strength heat-resistant concretes were examined according to the following methods, and the results are shown in table 4:
1. compressive strength: standard test blocks (refer to GB/T50081-2016 standard for testing mechanical properties of common concrete) are manufactured, and the compressive strength is measured when the standard test blocks are maintained for 1 day, 7 days and 28 days.
2. Compressive strength at high temperature: the compressive strength at high temperature was measured at standard cultivation for 28 days. The method for testing the compressive strength at high temperature comprises the following steps: taking 3 standard test blocks as a group in different embodiments and comparison examples, after standard curing for 28 days, drying for 24h at 110 ℃, burning for 3h at a constant temperature of 250 ℃, 400 ℃, 550 ℃ and 700 ℃ in a high-temperature furnace, naturally cooling to room temperature, and measuring the compression strength after burning.
3. Slump and density: the concrete is oxidized and formed under the same conditions for testing (refer to GB/T50080-2016 Standard test method for Performance of common concrete mixture).
4. Compressive strength after self-repair: taking 3 standard test blocks as a group in different and comparative examples, and measuring the compressive strength B after the standard culture for 28 days until cracks are generated; after self-healing for 28 days in an environment of 65% air humidity, the compressive strength was measured.
Table 4 test results of properties of concrete prepared in example 2 and comparative examples 1 to 4
As can be seen from the performance test results in Table 4, in comparison with the comparative examples 1-4 in which the coarse aggregate, the polypropylene fiber, the mineral powder, the composite fiber and the self-repairing material are added simultaneously, the compressive strength, the standard curing 28d high-temperature compressive strength, the density of the hardened concrete and the slump are generally lower, which indicates that the coarse aggregate and the composite fiber have good compounding effect, and the heat resistance and the strength of the concrete can be better improved by compounding the coarse aggregate and the composite fiber.
The comparison example 1 is not added with coarse aggregate, composite fiber and self-repairing material, compared with the comparison examples 2-4 which are added with coarse aggregate, polypropylene fiber and mineral powder or added with composite fiber, the density difference after hardening is not obvious, and the slump loss is slightly more than that of the comparison examples 2-4, which shows that the self-repairing material, the composite fiber, the coarse aggregate, the polypropylene fiber and the mineral powder have little influence on the hardness and slump of the prepared concrete. However, the 28-day compressive strength of the comparative example 1 is only 59.8MPa, the 28-day compressive strength loss is 26.6MPa at a high temperature of 250 ℃ to 700 ℃ in standard maintenance, and the compressive strength at a high temperature of 700 ℃ is only 28.7MPa, which is obviously inferior to that of the comparative examples 2-4, and it is demonstrated that even if the self-repairing material is added alone, the composite fiber, the coarse aggregate, the polypropylene fiber and the mineral powder can enable the concrete to have higher compressive strength and improve the heat resistance of the concrete, so that the concrete has higher strength and good heat resistance, but the effect of the composite fiber is slightly better than that of the coarse aggregate and the self-repairing material. In addition, according to the comparison between the embodiment 2 and the comparative examples 2-4, the addition of the self-repairing material does not affect the hardness and the slump of the prepared concrete, and can also generate a good compounding effect with the composite fiber, the coarse aggregate, the polypropylene fiber and the mineral powder respectively, so that the heat resistance and the compressive strength of the concrete are further improved.
In the self-repairing aspect, in the comparative example 2 and the comparative examples 2 to 4, under the condition that the preparation examples and the use amounts of the added self-repairing materials are the same, the self-repairing effect of the added composite fibers is obviously superior to that of the case without the addition of the composite fibers, and the self-repairing effect of the composite fibers added alone is slightly superior to that of the composite fibers added alone. Therefore, the self-repairing material can generate a good self-repairing compounding effect with the composite fiber, the coarse aggregate, the polypropylene fiber and the mineral powder, and the self-repairing capability of the prepared concrete is further improved.
TABLE 5 results of testing the properties of the concretes obtained in examples 1 to 5
As can be seen from the performance test results in table 5:
compared with the experimental results of the examples 1 to 3, the increase of the use amounts of the coarse aggregate, the polypropylene fiber, the mineral powder, the early strength agent and the composite fiber and the addition of the self-repairing material are all beneficial to the general improvement of the compressive strength, the standard curing 28d high-temperature compressive strength, the density after the concrete is hardened and the slump of the concrete. The benign compound effect generated by the self-repairing material, the composite fiber, the coarse aggregate, the polypropylene fiber and the mineral powder is improved along with the increase of the using amount. The performances of the examples 2 and 3 are improved compared with the performance of the example 1, and the self-repairing material further preferably added with calcined tuff and carbon nano tubes can improve the density, the slump stability and the pressure resistance of concrete.
Compared with the experimental results of the embodiments 2, 4 and 5, it can be found that the self-repairing materials with different proportions, especially the dosage of the calcined tuff and the carbon nanotubes can also influence the compressive strength, the standard-maintained 28d high-temperature compressive strength and the density and the slump of the prepared concrete after the concrete is hardened, and the higher the dosage or the proportion of the calcined tuff and the carbon nanotubes is, the more uniformly distributed in the concrete after the mixing, and the density, the slump stability and the compressive capacity of the concrete can be improved.
Comparing the experimental results of examples 1 to 5 and comparative examples 1 to 4, we can find that the most preferable case is example 5, which has a density slightly superior to that of other examples and comparative examples after hardening and a slump similar to that of other examples. The compressive strength of the alloy in standard culture for 3 days reaches 48.3MPa, the compressive strength of the alloy in standard culture for 28 days is close to 80MPa, and in a high-temperature experiment at 250-700 ℃, although the compressive strength is lost by 19.2MPa which is slightly higher than that of other examples, the final value of the alloy is 57.3MPa which is still higher than that of other examples and comparative examples; the most preferred embodiment is example 4, which shows that the amount and ratio of the calcined tuff and the carbon nanotubes in the self-repairing material can be selected according to the purpose of the concrete during the implementation process.
In the self-repairing aspect, compared with other embodiments, the self-repairing effect of the embodiment 1 is relatively poor, and only 23.2MPa is improved after repairing, because although the self-repairing effect of the concrete with cracks can be achieved only by the cement and the diluted epoxy resin formula, the self-repairing capability of the concrete can be further improved by adding the calcined limestone and the carbon nanotubes into the formula. Compared with the examples 1 to 3, it can be seen that the usage amount of the self-repairing material is in positive correlation with the self-repairing capability of the concrete, and the influence of the formula proportion of the self-repairing material is relatively small. Comparing examples 2, 4 and 5, it can be seen that the higher the usage of calcined limestone and carbon nanotubes in the formula, the better the self-repairing effect under the same usage of self-repairing material, presumably because the capillary effect of water vapor and moisture is improved by the multiple repair promoting mechanism of calcined tuff and the increase of carbon nanotube amount. In view of the combination of examples 1-5, the most preferred embodiment for repair is example 5, which still achieves a compressive strength of 70PMa after self-repair. From the perspective of improving the self-repairing compressive strength, the optimal scheme is embodiment 2, which illustrates that in the implementation process, the usage amount and the proportion of the calcined tuff and the carbon nanotubes in the self-repairing material can be selected according to the use requirement of concrete.
Claims (7)
1. The high-strength heat-resistant self-repairing concrete is characterized in that: the concrete comprises, by weight, 360 parts of 340-grade cement, 160 parts of 140-grade fly ash, 800 parts of 750-grade broken stone, 750 parts of 730-grade medium sand, 120 parts of 110-grade coarse aggregate, 1-5 parts of a water reducing agent, 180 parts of 170-grade water, 1-5 parts of polypropylene fiber, 50-80 parts of mineral powder, 1-5 parts of an early strength agent, 20-30 parts of composite fiber and 5-10 parts of a self-repairing material; the coarse aggregate is formed by mixing hollow glass microspheres and ceramsite in a mass ratio of 1: 1.2-1.5; the composite fiber comprises 5-10 parts of aramid fiber, 3-6 parts of glass fiber, 5-10 parts of resorcinol-formaldehyde resin and 0.3-1.4 parts of copolyoxymethylene; the self-repairing material comprises 6-8 parts of cement and 2-4 parts of diluted epoxy resin.
2. The high strength heat resistant self-repairing concrete of claim 1, wherein: the self-repairing material can also comprise 0.5-1 part of calcined tuff and 0.5-1 part of carbon nano tubes. The calcined tuff is acid tuff, which is prepared by grinding tuff, sieving with 200 mesh sieve, preheating with microwave at 600 deg.C for 10-30min at 300-.
3. The self-repairing material of claims 1 and 2, wherein: the preparation method comprises the steps of mixing and stirring the cement, the diluted epoxy resin, the calcined tuff and the carbon nano tubes which are weighed according to the formula ratio for 5-10min to form viscous liquid, extruding the viscous liquid into blocks by an extruding machine or a briquetting machine, and crushing the blocks into particles with the diameter of 30-50 mm by a crusher.
4. The high strength heat resistant self-repairing concrete of claim 1, wherein: the composite fiber is prepared by the following method:
(1) stirring resorcinol-formaldehyde resin at 95-105 deg.C, melting, adding aramid fiber and glass fiber, curing at room temperature for 6-8 hr, and pulverizing into particles with average particle diameter of 10-20 mm;
(2) melting the copolyformaldehyde at 180-200 ℃, carrying out ultrasonic treatment on the product obtained in the step (1), wherein the ultrasonic frequency is 23-25kHz, the time is 5-10min, adding the product into the copolyformaldehyde, uniformly mixing, drying at 80-90 ℃, and crushing the dried product into powder with the particle size of 1-5 mm.
5. The high strength heat resistant self-repairing concrete of claim 1, wherein: the resorcinol-formaldehyde resin is prepared by reacting resorcinol and formaldehyde in a mass ratio of 1:0.6-0.7 at the temperature of 100-150 ℃ and cooling; the length of the aramid fiber is 1-3mm, and the length of the glass fiber is 3-9 mm; the particle size of the hollow glass beads is 10-15mm, and the particle size of the ceramsite is 5-10 mm; the fly ash is F-class II-grade fly ash, the fly ash is low-calcium II-grade fly ash, the fineness (the screen residue of a 45-micrometer square-hole screen) is 8-12%, the water demand ratio is 95-98%, and the loss on ignition is 2-4.5%.
6. The high strength heat resistant self-repairing concrete of claim 1, wherein: the water reducing agent is one of an aliphatic (hydroxy) sulfonate high-efficiency water reducing agent, a naphthalene high-efficiency water reducing agent and a polycarboxylic acid high-efficiency water reducing agent; the fineness modulus of the medium sand is 2.3-3.0, the mud content is 2-2.6%, and the mud block content is 0.45-0.65%; the mineral powder is S95 grade mineral powder, the activity index in 28 days is 95%, and the fluidity ratio is 99%.
7. The preparation method for realizing the high-strength heat-resistant self-repairing concrete of the claims 1 to 5 is characterized by comprising the following steps of:
s1: quantitative weighing, namely weighing all the raw materials according to the components;
s2: fully and uniformly mixing cement, fly ash, broken stone, medium sand, mineral powder and coarse aggregate to prepare a premix;
s3: adding a water reducing agent, an early strength agent, polypropylene fibers and composite fibers into water, uniformly mixing, adding the mixture into a premix, fully mixing for 80-120min, then adding the prepared self-repairing material, fully mixing and uniformly shaking to prepare the high-strength heat-resistant self-repairing concrete.
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