CN110818366B - Fair-faced concrete and preparation process thereof - Google Patents
Fair-faced concrete and preparation process thereof Download PDFInfo
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- CN110818366B CN110818366B CN201911363948.2A CN201911363948A CN110818366B CN 110818366 B CN110818366 B CN 110818366B CN 201911363948 A CN201911363948 A CN 201911363948A CN 110818366 B CN110818366 B CN 110818366B
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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
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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
- C04B20/023—Chemical 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
- 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
- C04B20/10—Coating or impregnating
- C04B20/1055—Coating or impregnating with inorganic materials
- C04B20/1062—Metals
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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
- C04B20/10—Coating or impregnating
- C04B20/1055—Coating or impregnating with inorganic materials
- C04B20/1074—Silicates, e.g. glass
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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
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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 relates to fair-faced concrete and a preparation process thereof, belonging to the technical field of concrete. The fair-faced concrete comprises, by weight, 180 parts of cement, 110 parts of water, 160 parts of modified and regenerated coarse aggregate, 960 parts of 1150 parts of 960 parts of 1150 parts of 480 parts of fine aggregate, 50-105 parts of fly ash, 95-120 parts of mineral powder, 50-140 parts of glass powder, 30-60 parts of calcium oxide, 3-7 parts of a water reducer and 2-5 parts of an air entraining agent; the preparation method of the modified recycled coarse aggregate comprises the following steps: s1: taking waste concrete, crushing and screening to obtain regenerated coarse aggregate; s2: immersing the recycled coarse aggregate into a citric acid solution with the mass concentration of 4-6%, and airing; s3: stirring 50-70 parts of polyvinyl alcohol, 20-60 parts of sodium silicate and 500-700 parts of water to obtain a modified solution for later use; s4: and soaking the recycled coarse aggregate obtained in the step S2 into the modification liquid in the step S3, taking out the recycled coarse aggregate, and baking the recycled coarse aggregate at the temperature of 150 ℃ and 180 ℃ to obtain the modified recycled coarse aggregate. The fair-faced concrete has the effect of better compressive strength.
Description
Technical Field
The invention relates to the technical field of concrete, in particular to fair-faced concrete and a preparation process thereof.
Background
The fair-faced concrete is the fair-faced concrete which directly utilizes the natural texture of the formed fair-faced concrete as the veneer effect, and does not need surface treatment such as spraying, so that the individuality can be revealed, the environmental protection is facilitated, and the market share of the fair-faced concrete is gradually enlarged along with the individuation pursuit of people and the enhancement of environmental protection consciousness.
In the fair-faced concrete, the aggregate dosage is the first and is the component with the largest volume and specific gravity. The disorderly exploitation of natural sandstone resources brought by the application of aggregates causes damage to mountain vegetation and damage to river channels, so that the development and application of waste concrete construction waste as recycled coarse aggregates are more and more valued by people.
However, because the waste concrete needs to be subjected to a large external force in the process of disintegration and crushing, micro cracks are easy to appear in the aggregate, and in addition, porous old cement mortar is remained on the surface of the regenerated aggregate, so that the porosity of the regenerated aggregate is increased, and the water absorption rate of the regenerated aggregate are increased. Therefore, the compressive strength of the fair-faced concrete prepared by adopting the regenerated aggregate is easily influenced, and even the service life of the fair-faced concrete is influenced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the fair-faced concrete which has a better compressive strength effect.
The technical purpose of the invention is realized by the following technical scheme:
the clear water concrete comprises the following components in parts by weight: 180 parts of cement, 110 parts of water, 160 parts of modified recycled coarse aggregate, 960 parts of 1150 parts of fine aggregate, 480 parts of fine aggregate, 50-105 parts of fly ash, 95-120 parts of mineral powder, 50-140 parts of glass powder, 30-60 parts of calcium oxide, 3-7 parts of a water reducer and 2-5 parts of an air entraining agent; the preparation method of the modified recycled coarse aggregate comprises the following steps:
s1: taking waste concrete, crushing the waste concrete, and screening to obtain recycled coarse aggregate with the particle size of 5-25 mm;
s2: soaking the recycled coarse aggregate in the step S1 in a citric acid solution with the mass concentration of 4-6% for 1-2h, and then airing;
s3: according to the parts by weight, 50-70 parts of polyvinyl alcohol, 20-60 parts of sodium silicate and 500-700 parts of water are fully stirred to obtain a modified solution for later use;
s4: and (4) soaking the regenerated coarse aggregate obtained in the step S2 into the modification solution obtained in the step S3 for 1.5-2.5h, taking out, and baking at the temperature of 150-180 ℃ for 1.5-2.5h to obtain the modified regenerated coarse aggregate.
The poor compressive strength of the fair-faced concrete prepared from the recycled coarse aggregate is mainly caused by the fact that the porosity of the recycled coarse aggregate is high due to fine cracks in the recycled coarse aggregate and residual porous old cement mortar on the surface of the recycled coarse aggregate, so that the compactness of the fair-faced concrete is poor, and the compressive strength is reduced. By adopting the technical scheme, the compactness of the recycled coarse aggregate is improved by modifying the recycled coarse aggregate, filling and sealing the pores of the recycled coarse aggregate, so that the compactness of the prepared fair-faced concrete is effectively improved, and the compressive strength and the durability of the fair-faced concrete are improved.
The regenerated coarse aggregate is soaked by the citric acid solution, and the citric acid can dissolve the old mortar remained on the regenerated coarse aggregate, so that the old mortar adhered to the surface of the regenerated coarse aggregate is reduced, and the porosity and the water absorption of the regenerated coarse aggregate are reduced. Meanwhile, after the used mortar adhered to the surface of the recycled coarse aggregate is dissolved by the citric acid, the appearance of the recycled coarse aggregate is improved, the sphericity of the recycled coarse aggregate is improved, and the fluidity of the recycled coarse aggregate is increased, so that the compactness and the compressive strength of the fair-faced concrete are improved.
The regenerated coarse aggregate soaked by the citric acid is modified by the modifying liquid prepared from the polyvinyl alcohol and the sodium silicate, firstly, the polyvinyl alcohol and the sodium silicate are used for filling cracks and pores in the regenerated coarse aggregate, and the polyvinyl alcohol has a good bonding effect and can increase the bonding strength with the regenerated coarse aggregate, so that the filling effect on the regenerated coarse aggregate is improved, and the porosity of the regenerated coarse aggregate is reduced.
In addition, the sodium silicate can react with citric acid to generate silicic acid and sodium citrate, and the citric acid adhered to the recycled coarse aggregate is reduced, so that the corrosion of the citric acid to the fair-faced concrete is reduced, and the durability of the fair-faced concrete is improved. After being soaked in the modifying solution, the clear water concrete is baked at the temperature of 180 ℃ below zero plus 150 ℃, so that the generated silicic acid is decomposed to avoid corrosion of the silicic acid to the clear water concrete, and the silicon dioxide generated by the decomposition of the silicic acid can be used as a cementing material of the concrete to fill the pores of the clear water concrete, thereby improving the compactness of the clear water concrete and further improving the compressive strength.
The sodium citrate can reduce the hydration heat of cement in the concrete, play a role in retarding coagulation, improve the setting time of the concrete, reduce the condition that the cement generates cracks, and improve the tensile, compressive and frost resistance properties of the concrete, thereby improving the working performance of the concrete. Meanwhile, sodium citrate and calcium ions form a soluble complex, so that the speed of calcium hydroxide separating out from the cement is reduced, the possibility of reaction of sulfate ions and calcium hydroxide is reduced, the generation of ettringite crystals and gypsum is delayed, and the corrosion of the sulfate ions to the concrete is reduced.
The glass powder is used as an admixture, so that the using amount of cement can be reduced, the emission of carbon dioxide is reduced, the environment protection is facilitated, the surface of the fair-faced concrete doped with the glass powder has a good mirror effect, and the prepared fair-faced concrete has uniform color and good glossiness; and when the glass powder is used as an admixture, the glass powder has a good gelling effect, the adhesiveness of the fair-faced concrete is enhanced, and the strength of the concrete is improved.
Although the glass powder contains active ingredients, the activity is latent, and the activation is carried out by an exciting agent, a proper amount of calcium oxide is added, the calcium oxide reacts with water to produce calcium hydroxide, the calcium hydroxide reacts with the glass powder to excite the pozzolanic activity of the glass powder, so as to generate a gelling product such as calcium silicate hydrate and the like, fill the pores of the fair-faced concrete and improve the compactness of the fair-faced concrete.
The present invention in a preferred example may be further configured to: the weight ratio of the glass powder to the calcium oxide is 1.5-3.5.
By adopting the technical scheme, the activation effect on the glass powder is not obvious when the content of calcium oxide is low; when the content of the calcium oxide is excessive, excessive calcium hydroxide crystals can be generated, so that expansion cracking is caused, the internal structure defects of the fair-faced concrete are serious, the compressive strength and the crack resistance of the fair-faced concrete are influenced, and the fair-faced concrete is adversely influenced, so that the effect is optimal when the weight ratio of the glass powder to the calcium oxide is 1.5-3.5.
The present invention in a preferred example may be further configured to: the weight ratio of the polyvinyl alcohol to the sodium silicate is 1.1-1.5.
By adopting the technical scheme, the sodium silicate and the calcium hydroxide in the cement can generate hydrated calcium silicate gel, the hydrated calcium silicate gel has water absorption, the water absorption of the modified recycled aggregate is reduced, the compactness of the fair-faced concrete can be filled, and the surface of the recycled aggregate is more compact. However, when the produced hydrated calcium silicate is too gelled, a large amount of water is absorbed, so that the water absorption of the recycled aggregate is increased again, and thus, the effect is most preferable when the weight ratio of the polyvinyl alcohol to the sodium silicate is 1.0 to 1.5.
The present invention in a preferred example may be further configured to: the raw materials also comprise 7-18 parts of steel fibers in parts by weight.
Through adopting above-mentioned technical scheme, steel fibre is three-dimensional in disorder to the distribution in the concrete, and after the clear water concrete is about to appear the crack or the crack appears, steel fibre passes through the bonding force transmission load with clear water concrete matrix interface, reduces the tensile stress of clear water concrete at crack edge to reach the effect that prevents the production and the development of crack, can reduce the spalling of clear water concrete, improve clear water concrete's compressive strength and rupture strength.
The present invention in a preferred example may be further configured to: the steel fiber is rough-surface steel fiber, and the preparation method comprises the following steps:
a. after the surface of the steel wire is degreased, washing the steel wire with clean water until the washing liquid is neutral;
b. b, placing the steel wire in the step a into an electroplating bath containing copper, carrying out copper plating on the steel wire, and drying the steel wire after the copper plating is finished to obtain the steel wire with the roughness of more than 20 microns;
c. and c, performing compression molding on the steel wire obtained in the step b and cutting to obtain the steel fiber with rough surface.
Through adopting above-mentioned technical scheme, the surperficial unevenness of the rough shaped steel fibre in surface increases steel fibre and fair-faced concrete's occlusal force and frictional resistance, increases steel fibre and fair-faced concrete's joint strength, is convenient for transmit the load for the part that links to each other but not ftracture through the bridging better, increases fair-faced concrete's toughness to improve tensile strength, anti folding performance and the compressive property of concrete.
The present invention in a preferred example may be further configured to: the length-diameter ratio of the rough-surface steel fiber is 30-80.
By adopting the technical scheme, when the length and diameter of the rough-surface steel fiber are smaller, the connection strength to the bare concrete is poorer, when the bare concrete cracks, the pulling strength to the bare concrete is smaller, but the compactness of the bare concrete is influenced, and the reinforcing effect of the rough-surface steel fiber is greatly weakened; when the length-diameter ratio of the rough-surface steel fiber is larger, knotting and agglomeration are easy to occur in the blending process, so that the reinforcing effect of the rough-surface steel fiber is reduced, and when the length-diameter ratio of the rough-surface steel fiber is 30-80, the effect of improving the tensile strength and the breaking strength of the fair-faced concrete is optimal.
The present invention in a preferred example may be further configured to: the apparent density range of the recycled coarse aggregate is 2300-2400kg/m3The water absorption is 6-12%, and the crushing index value is 15-20%.
By adopting the technical scheme, the apparent density, the bulk density and the water absorption of the recycled coarse aggregate are lower than the requirements of the national standard on the coarse aggregate, and the clear water concrete with better compressive strength is prepared by modifying the recycled coarse aggregate, which shows that the performance of the recycled coarse aggregate can be effectively improved according to the modification method.
The present invention in a preferred example may be further configured to: the fine aggregate is natural sand, and the fineness modulus is 3.0-2.3.
By adopting the technical scheme, the natural sand with larger fineness modulus can cause the segregation, bleeding and poor wrapping property of the fair-faced concrete, so that the modified recycled coarse aggregate in the fair-faced concrete is easy to expose outside, and the strength of the fair-faced concrete is reduced. The machine-made sand with smaller fineness modulus can cause poor fluidity and small slump of the fair-faced concrete and can not meet the requirements of site construction, and the main reason is that the content of stone powder in natural sand is larger, partial rubber materials can be replaced in the fair-faced concrete, the water demand is increased, and the fair-faced concrete is hard, has no fluidity and can not be tamped, thereby seriously affecting the compressive strength of the fair-faced concrete.
The present invention in a preferred example may be further configured to: the water reducing agent is a polycarboxylic acid water reducing agent.
By adopting the technical scheme, the polycarboxylic acid is a high-performance water reducing agent, is a cement dispersing agent in the application of cement concrete, can reduce the mixing water consumption under the condition of keeping the cement fluidity and the using amount unchanged, thereby reducing the water cement ratio, reducing the communicated pores formed by excessive cement hydration in the solidification process of the concrete, increasing the compactness of the concrete, improving the compressive strength of the concrete and further improving the durability of the concrete.
Object two of the present invention: there is provided a process for the preparation of an as-cast finish concrete as claimed in any one of claims 1 to 3, comprising the steps of: based on the weight portion, the weight portion of the material is,
s1: mixing the modified regenerated coarse aggregate, the fine aggregate and half of water in parts by weight, and uniformly stirring to obtain an aggregate mixture;
s2: and adding the cement, the fly ash, the mineral powder, the glass powder, the calcium oxide, the water reducing agent, the air entraining agent and the balance of water into the aggregate mixture prepared in the step S1, and uniformly stirring to obtain the fair-faced concrete.
The third purpose of the invention is that: there is provided a process for the preparation of an as-cast-finish concrete as claimed in any one of claims 4 to 8, comprising the steps of: based on the weight portion, the weight portion of the material is,
s1: mixing the modified recycled coarse aggregate, the fine aggregate, the steel fiber and half of water in parts by weight, and uniformly stirring to obtain an aggregate mixture;
s2: and adding the cement, the fly ash, the mineral powder, the glass powder, the calcium oxide, the water reducing agent, the air entraining agent and the balance of water into the aggregate mixture prepared in the step S1, and uniformly stirring to obtain the fair-faced concrete.
By adopting the technical scheme, firstly, half of water in parts by weight is adopted to pre-wet the modified recycled coarse aggregate, the fine aggregate and the steel fiber, so that the modified recycled coarse aggregate, the fine aggregate and the steel fiber are conveniently and uniformly dispersed, the inactive dust on the surface of the recycled coarse aggregate is reduced, and the strength of the fair-faced concrete is favorably improved; then, raw materials such as cement, fly ash, mineral powder and the like are added, so that the cement, the fly ash and the mineral powder fill some pores and cracks, the compactness of the fair-faced concrete is increased, and the compressive strength is improved.
In summary, the invention includes at least one of the following beneficial technical effects:
1. the regenerated coarse aggregate is modified after being soaked in the citric acid and the modifying solution, so that the compactness and sphericity of the regenerated coarse aggregate are improved, the apparent density of the regenerated coarse aggregate is improved, the water absorption is reduced, and the compactness, the compression resistance and the durability of the fair-faced concrete are improved. The glass powder can improve the mirror effect of the fair-faced concrete, and simultaneously, the calcium oxide reacts with water to produce calcium hydroxide, so that the volcanic ash activity of the glass powder is excited, gelled products such as calcium silicate hydrate and the like are generated, the pores of the fair-faced concrete are filled, the compactness of the fair-faced concrete is improved, and the compressive strength of the fair-faced concrete is improved;
2. the rough-surface steel fibers are distributed in the concrete in a three-dimensional disorderly manner, and the rough-surface steel fibers transmit load through the bonding force with the bare concrete matrix interface, so that the tensile stress of the bare concrete at the edge of a crack is reduced, the effect of preventing the crack from generating and developing is achieved, and the compressive strength and the fracture resistance of the bare concrete are improved.
Detailed Description
The present invention will be described in further detail with reference to examples.
In the following examples and comparative examples:
the cement is P.O42.5 ordinary portland cement produced by Yangquan Jidong cement factories;
the fly ash is grade II fly ash produced by Lihui mineral products Co., Ltd in Dongguan city;
the mineral powder is S95 mineral powder produced by Lihui mineral products Co., Ltd, Dongguan city;
the apparent density range of the recycled coarse aggregate is 2300-2400kg/m3The water absorption rate is 6-12%, and the crushing index value is 15-20%;
the fine aggregate is natural sand produced by Yongxing stone factory of Shouyang, and the fineness modulus of the natural sand is 3.0-2.3;
the steel fiber is rough-surface steel fiber produced by Tianyi engineering fiber company Limited in Changzhou city;
the water reducing agent is a polycarboxylic acid water reducing agent produced by Shanxi Baichuan-sourced novel building materials Co;
the air entraining agent is rosin soap produced by Shanxi Baichuan-sourced novel building material company Limited;
the silica fume is purchased from silicon micro-silica powder company of the Minam Pengcheng;
the glass powder is purchased from Hubei Xingdong Chengcheng chemical Co Ltd;
calcium oxide, polyvinyl alcohol and sodium silicate are all purchased from chemical markets of Shandong Jinan city.
Example 1
The clear water concrete comprises, by weight, 180 parts of cement, 110 parts of water, 960 parts of recycled coarse aggregate, 480 parts of natural sand, 50 parts of fly ash, 95 parts of mineral powder, 50 parts of glass powder, 30 parts of calcium oxide, 3 parts of a water reducing agent and 2 parts of an air entraining agent; the preparation method of the fair-faced concrete comprises the following steps:
the preparation method of the modified recycled coarse aggregate comprises the following steps:
s1: taking waste concrete, crushing the waste concrete, and screening to obtain recycled coarse aggregate with the particle size of 5-25 mm;
s2: soaking the recycled coarse aggregate in the step S1 in a citric acid solution with the mass concentration of 4% for 1h, and then airing;
s3: mixing 50 parts by weight of polyvinyl alcohol, 20 parts by weight of sodium silicate and 500 parts by weight of water, and fully stirring to obtain a modified solution for later use;
s4: and (4) soaking the regenerated coarse aggregate obtained in the step (S2) into the modification liquid obtained in the step (S3) for 1.5h, taking out, placing at the temperature of 150 ℃, and baking for 1.5h to obtain the modified regenerated coarse aggregate.
The preparation method of the fair-faced concrete comprises the following steps:
s5: mixing the modified recycled coarse aggregate, the natural sand and half of water in parts by weight, and uniformly stirring to obtain an aggregate mixture;
s6: and adding the cement, the fly ash, the mineral powder, the glass powder, the calcium oxide, the water reducing agent, the air entraining agent and the balance of water into the aggregate mixture prepared in the step S5, and uniformly stirring to obtain the fair-faced concrete.
Example 2
The clear water concrete comprises, by weight, 255 parts of cement, 135 parts of water, 1055 parts of recycled coarse aggregate, 555 parts of natural sand, 77.5 parts of fly ash, 107.5 parts of mineral powder, 95 parts of glass powder, 45 parts of calcium oxide, 5 parts of a water reducing agent and 3.5 parts of an air entraining agent;
the preparation method of the fair-faced concrete comprises the following steps:
the preparation method of the modified recycled coarse aggregate comprises the following steps:
s1: taking waste concrete, crushing the waste concrete, and screening to obtain recycled coarse aggregate with the particle size of 5-25 mm;
s2: soaking the recycled coarse aggregate in the step S1 in a citric acid solution with the mass concentration of 5% for 1.5h, and then airing;
s3: mixing 60 parts by weight of polyvinyl alcohol, 40 parts by weight of sodium silicate and 600 parts by weight of water, and fully stirring to obtain a modified solution for later use;
s4: and (4) soaking the regenerated coarse aggregate obtained in the step (S2) into the modification solution obtained in the step (S3) for 2 hours, taking out, placing at 165 ℃ and baking for 2 hours to obtain the modified regenerated coarse aggregate.
The preparation method of the fair-faced concrete comprises the following steps:
s5: mixing the modified recycled coarse aggregate, the natural sand and half of water in parts by weight, and uniformly stirring to obtain an aggregate mixture;
s6: and adding the cement, the fly ash, the mineral powder, the glass powder, the calcium oxide, the water reducing agent, the air entraining agent and the balance of water into the aggregate mixture prepared in the step S5, and uniformly stirring to obtain the fair-faced concrete.
Example 3
The clear water concrete comprises, by weight, 330 parts of cement, 160 parts of water, 1150 parts of recycled coarse aggregate, 630 parts of natural sand, 105 parts of fly ash, 120 parts of mineral powder, 140 parts of glass powder, 60 parts of calcium oxide, 7 parts of a water reducing agent and 5 parts of an air entraining agent;
the preparation method of the fair-faced concrete comprises the following steps:
the preparation method of the modified recycled coarse aggregate comprises the following steps:
s1: taking waste concrete, crushing the waste concrete, and screening to obtain recycled coarse aggregate with the particle size of 5-25 mm;
s2: soaking the recycled coarse aggregate in the step S1 in a citric acid solution with the mass concentration of 6% for 2h, and then airing;
s3: mixing 70 parts of polyvinyl alcohol, 60 parts of sodium silicate and 700 parts of water in parts by weight, and fully stirring to obtain a modified solution for later use;
s4: and (4) soaking the regenerated coarse aggregate obtained in the step (S2) into the modification solution obtained in the step (S3) for 2.5h, taking out, placing at 180 ℃, and baking for 2.5h to obtain the modified regenerated coarse aggregate.
The preparation method of the fair-faced concrete comprises the following steps:
s5: mixing the modified recycled coarse aggregate, the natural sand and half of water in parts by weight, and uniformly stirring to obtain an aggregate mixture;
s6: and adding the cement, the fly ash, the mineral powder, the glass powder, the calcium oxide, the water reducing agent, the air entraining agent and the balance of water into the aggregate mixture prepared in the step S5, and uniformly stirring to obtain the fair-faced concrete.
Example 4
The clear water concrete is different from the clear water concrete in the embodiment 2 in that the adopted components comprise 90 parts of glass powder and 60 parts of calcium oxide, namely the weight ratio of the glass powder to the calcium oxide is 1.5.
Example 5
The clear water concrete is different from the clear water concrete in the embodiment 2 in that the adopted components comprise 90 parts of glass powder and 36 parts of calcium oxide, namely the weight ratio of the glass powder to the calcium oxide is 2.5.
Example 6
The clear water concrete is different from the clear water concrete in the embodiment 2 in that the adopted components comprise 140 parts of glass powder and 40 parts of calcium oxide, namely the weight ratio of the glass powder to the calcium oxide is 3.5.
Example 7
A bare concrete, which is different from that in example 2 in that 55 parts of polyvinyl alcohol and 50 parts of sodium silicate are used as components in step S3, i.e., the weight ratio of polyvinyl alcohol to sodium silicate is 1.1.
Example 8
A bare concrete, which is different from that in example 2 in that 52 parts of polyvinyl alcohol and 40 parts of sodium silicate are used as components in step S3, i.e., the weight ratio of polyvinyl alcohol to sodium silicate is 1.3.
Example 9
A bare concrete, which is different from that in embodiment 2 in that the components used in step S3 include 60 parts of polyvinyl alcohol and 40 parts of sodium silicate, i.e., the weight ratio of polyvinyl alcohol to sodium silicate is 1.5.
Example 10
A bare concrete, which is different from example 2 in that 7 parts of steel fibers, in which the length-diameter ratio of the steel fibers is 30, are added in step S5.
Example 11
A bare concrete, which is different from example 2 in that 12.5 parts of steel fibers, wherein the length-diameter ratio of the steel fibers is 55, are added in step S5.
Example 12
An as-cast finish concrete is different from example 2 in that 18 parts of steel fibers are added in step S5, wherein the length-diameter ratio of the steel fibers is 80.
Example 13
A fair-faced concrete is different from the concrete in example 11 in that steel fibers are rough-surfaced steel fibers, and the preparation method comprises the following steps:
a. after the surface of the steel wire is degreased, washing the steel wire with clean water until the washing liquid is neutral;
b. b, placing the steel wire in the step a into an electroplating bath containing copper, carrying out copper plating on the steel wire, and drying the steel wire after the copper plating is finished to obtain the steel wire with the roughness of more than 20 microns;
c. and c, performing compression molding on the steel wire obtained in the step b and cutting to obtain the steel fiber with rough surface.
Comparative example 1
The clear water concrete is different from the embodiment 2 in that the modified recycled coarse aggregate is replaced by the unmodified recycled coarse aggregate in the same parts in the adopted components.
Comparative example 2
The clear water concrete is different from the clear water concrete in the embodiment 5 in that the adopted components comprise 60 parts of glass powder and 50 parts of calcium oxide, namely the weight ratio of the glass powder to the calcium oxide is 1.2.
Comparative example 3
The clear water concrete is different from the clear water concrete in the embodiment 5 in that the adopted components comprise 133 parts of glass powder and 35 parts of calcium oxide, namely the weight ratio of the glass powder to the calcium oxide is 3.8.
Comparative example 4
A bare concrete, which is different from that in example 8 in that 54 parts of polyvinyl alcohol and 60 parts of sodium silicate are used as components in step S3, namely, the weight ratio of polyvinyl alcohol to sodium silicate is 0.9.
Comparative example 5
A bare concrete, which is different from that in example 8 in that 54 parts of polyvinyl alcohol and 30 parts of sodium silicate are used as components in step S3, namely, the weight ratio of polyvinyl alcohol to sodium silicate is 1.8.
Comparative example 6
An as-cast finish concrete, which is different from that of example 11, was prepared by using steel fibers having an aspect ratio of 25.
Comparative example 7
An as-cast finish concrete, which is different from that of example 11, was prepared by using steel fibers having a length-diameter ratio of 90.
The properties of the concrete of examples 1 to 13 and comparative examples 1 to 7 were measured by the following methods.
Compressive strength: and (3) manufacturing a standard test block according to GB/T50081-2016 standard of mechanical property test method of common concrete, and measuring the compressive strength of the standard test block maintained for 7 days and 28 days.
Bending strength: and (3) manufacturing a standard test block according to GB/T50081-2016 standard of mechanical property test method for common concrete, and measuring the flexural strength of the standard test block for 7d and 28d of maintenance.
And thirdly, detecting the water absorption (%) of the fair-faced concrete according to ASTMC1585-2013 Standard test method for measuring the water absorption of the hydraulic cement concrete.
Resistance to chloride ion permeability: and testing the chloride ion penetration depth of the standard test block according to a rapid chloride ion migration coefficient method in GB/T50082-2009 test method standard for long-term performance and durability of common concrete.
The concrete test results of examples 1 to 13 and comparative examples 1 to 7 are shown in Table 1.
TABLE 1 concrete durability test data
From table 1, it can be seen that:
the properties of the fair-faced concrete in the examples 1 to 13 are all superior to those of the fair-faced concrete in the comparative examples 1 to 7, which shows that the mutual relationship among the formulas of the fair-faced concrete of the invention is scientific and reasonable, the fair-faced concrete prepared by the invention has good compression resistance, bending resistance, water and chloride ion permeability resistance, and the recycled coarse aggregate is used for replacing the natural coarse aggregate, so that the cost is saved, the resource is recycled, and the prepared fair-faced concrete has excellent compression strength and permeability resistance.
In examples 10 to 12, compared with examples 1 to 2, the breaking strength, the compressive strength, the water absorption and the chloride ion permeation resistance of the fair-faced concrete in examples 10 to 12 are significantly improved, which indicates that the addition of the steel fiber can prevent the generation and the development of cracks on the fair-faced concrete, reduce the defects of the internal structure of the fair-faced concrete, improve the compactness of the fair-faced concrete, and improve the compression resistance, the breaking resistance, the water absorption and the chloride ion permeation resistance of the fair-faced concrete.
In example 13, compared with examples 10 to 12, the breaking strength, the compressive strength, the water absorption and the chloride ion permeation resistance of the fair-faced concrete in example 13 are significantly improved, which indicates that after the steel fibers are subjected to surface roughness treatment, the biting force and the frictional resistance of the steel fibers and the fair-faced concrete can be increased, the connection strength of the steel fibers and the fair-faced concrete is increased, and the toughness of the fair-faced concrete is increased, so that the tensile property, the breaking resistance and the compressive property of the concrete are improved.
Compared with the example 2, the breaking strength, the compressive strength, the water absorption and the chlorine ion permeation resistance of the fair-faced concrete in the comparative example 1 are obviously reduced, which shows that after the recycled coarse aggregate is treated by the method disclosed by the invention, the pore structure of the recycled coarse aggregate can be improved, the porosity of the recycled coarse aggregate is reduced, the mechanical property and the permeability resistance of the recycled coarse aggregate are improved, so that the compressive strength, the water absorption and the chlorine ion permeation resistance of the fair-faced concrete are improved, and the durability of the fair-faced concrete is improved.
Compared with the example 5, the bending strength, the compressive strength, the water absorption and the chloride ion permeation resistance of the fair-faced concrete in the comparative examples 2-3 are obviously reduced, which shows that the weight ratio of the glass powder to the calcium oxide has a larger influence on the performance of the fair-faced concrete, when the addition amount of the calcium oxide is smaller, the activity of the glass powder cannot be better excited, and when the addition amount of the calcium oxide is too large, excessive calcium hydroxide crystals are generated to cause expansion cracking and influence the compressive strength and the crack resistance of the fair-faced concrete, so that the effect is best when the weight ratio of the glass powder to the calcium oxide is 1.5-3.5.
Compared with the embodiment 8, the breaking strength, the compressive strength, the water absorption and the chloride ion permeation resistance of the fair-faced concrete in the comparative examples 4-5 are obviously reduced, which shows that when the weight ratio of the polyvinyl alcohol to the sodium silicate is 1.1-1.5, the modified effect on the regenerated coarse aggregate is better, so that the prepared fair-faced concrete has better breaking strength, compressive strength, water absorption and chloride ion permeation resistance, and the durability of the fair-faced concrete is improved.
The bending strength, compressive strength, water absorption and chloride ion permeability of the fair-faced concrete in comparative examples 6-7 are significantly reduced compared to example 11, indicating that the aspect ratio of the steel fiber is in the range of 30-80 with the best effect.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (9)
1. The fair-faced concrete is characterized by comprising the following components in parts by weight: 180 parts of cement, 110 parts of water, 160 parts of modified recycled coarse aggregate, 960 parts of 1150 parts of fine aggregate, 480 parts of fine aggregate, 50-105 parts of fly ash, 95-120 parts of mineral powder, 50-140 parts of glass powder, 30-60 parts of calcium oxide, 3-7 parts of a water reducer and 2-5 parts of an air entraining agent; the preparation method of the modified recycled coarse aggregate comprises the following steps:
s1: taking waste concrete, crushing the waste concrete, and screening to obtain recycled coarse aggregate with the particle size of 5-25 mm;
s2: soaking the recycled coarse aggregate in the step S1 in a citric acid solution with the mass concentration of 4-6% for 1-2h, and then airing;
s3: according to the parts by weight, 50-70 parts of polyvinyl alcohol, 20-60 parts of sodium silicate and 700 parts of 500-one sodium silicate are fully stirred to obtain a modified solution for later use, wherein the weight ratio of the polyvinyl alcohol to the sodium silicate is 1.1-1.5;
s4: and (4) soaking the regenerated coarse aggregate obtained in the step S2 into the modification solution obtained in the step S3 for 1.5-2.5h, taking out, and baking at the temperature of 150-180 ℃ for 1.5-2.5h to obtain the modified regenerated coarse aggregate.
2. The fair-faced concrete of claim 1, wherein: the weight ratio of the glass powder to the calcium oxide is 1.5-3.5.
3. The fair-faced concrete of claim 1, wherein: the raw materials also comprise 7-18 parts of steel fibers in parts by weight.
4. Bare concrete according to claim 3, characterised in that: the steel fiber is rough-surface steel fiber, and the preparation method comprises the following steps:
a. after the surface of the steel wire is degreased, washing the steel wire with clean water until the washing liquid is neutral;
b. b, placing the steel wire in the step a into an electroplating bath containing copper, carrying out copper plating on the steel wire, and drying the steel wire after the copper plating is finished to obtain the steel wire with the roughness of more than 20 microns;
c. and c, performing compression molding on the steel wire obtained in the step b and cutting to obtain the steel fiber with rough surface.
5. The fair-faced concrete of claim 4, wherein: the length-diameter ratio of the rough-surface steel fiber is 30-80.
6. The fair-faced concrete of claim 1, wherein: the apparent density range of the recycled coarse aggregate before modification is 2300-2400kg/m3The water absorption is 6-12%, and the crushing index value is 15-20%.
7. The fair-faced concrete of claim 1, wherein: the fine aggregate is natural sand, and the fineness modulus is 3.0-2.3.
8. A process for the preparation of an as-cast finish concrete as claimed in any one of claims 1 to 2, characterised in that: the method comprises the following steps: based on the weight portion, the weight portion of the material is,
s1: mixing the modified regenerated coarse aggregate, the fine aggregate and half of water in parts by weight, and uniformly stirring to obtain an aggregate mixture;
s2: and adding the cement, the fly ash, the mineral powder, the glass powder, the calcium oxide, the water reducing agent, the air entraining agent and the balance of water into the aggregate mixture prepared in the step S1, and uniformly stirring to obtain the fair-faced concrete.
9. A process for the preparation of the bare concrete according to any one of claims 3 to 5, characterised in that: the method comprises the following steps: based on the weight portion, the weight portion of the material is,
s1: mixing the modified recycled coarse aggregate, the fine aggregate, the steel fiber and half of water in parts by weight, and uniformly stirring to obtain an aggregate mixture;
s2: and adding the cement, the fly ash, the mineral powder, the glass powder, the calcium oxide, the water reducing agent, the air entraining agent and the balance of water into the aggregate mixture prepared in the step S1, and uniformly stirring to obtain the fair-faced concrete.
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| CN114890757A (en) * | 2022-06-30 | 2022-08-12 | 深圳市衡骏环保科技有限公司 | Recycled aggregate concrete and preparation method thereof |
| CN115745514A (en) * | 2022-11-22 | 2023-03-07 | 江苏省送变电有限公司 | Modified regenerated clear water concrete and preparation method thereof |
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