CN112830740B - Fair-faced concrete produced from construction waste recycled aggregate - Google Patents
Fair-faced concrete produced from construction waste recycled aggregate Download PDFInfo
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- CN112830740B CN112830740B CN202110089842.9A CN202110089842A CN112830740B CN 112830740 B CN112830740 B CN 112830740B CN 202110089842 A CN202110089842 A CN 202110089842A CN 112830740 B CN112830740 B CN 112830740B
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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
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/16—Waste materials; Refuse from building or ceramic industry
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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
- C04B20/12—Multiple coating or impregnating
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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 application relates to the field of concrete, and specifically discloses fair-faced concrete produced by construction waste recycled aggregate, which is prepared from the following raw materials in parts by weight: 420 parts of cement 360-fold, 42-65 parts of fly ash, 15-28 parts of mineral powder, 730 parts of river sand 710-fold, 1200 parts of modified recycled coarse aggregate 1100-fold, 5.6-7.8 parts of admixture, 5-8.6 parts of composite fiber and 180 parts of water 150-fold; the modified recycled coarse aggregate is prepared by the following method: pretreating waste concrete to prepare a regenerated coarse aggregate, weighing modified acrylate emulsion, modified diatomite and chitosan film liquid, sequentially spraying the modified acrylate emulsion, the modified diatomite and the chitosan film liquid on the surface of the regenerated coarse aggregate, and drying to prepare a modified regenerated coarse aggregate; the method has the effect of preventing acid radical ions from entering the internal structure of the concrete and influencing the strength of the fair-faced concrete.
Description
Technical Field
The application relates to the field of concrete, in particular to fair-faced concrete produced by building waste recycled aggregate.
Background
After the fair-faced concrete is poured, materials such as ceramic tiles, stone materials and the like are not coated on the surface of the fair-faced concrete any more, and the fair-faced concrete shows a plain state, and is also called as decorative concrete due to the extremely good decorative effect.
The construction waste recycled aggregate is obtained by crushing, cleaning and grading construction waste concrete blocks, and then screening out the aggregate again for reuse; as the waste concrete blocks can be subjected to larger external force in the crushing process, a large number of fine cracks can appear on the surface and the inside of the screened aggregate, so that the water absorption rate of the recycled aggregate is improved, and the cement mortar in the recycled aggregate also has the effect of increasing the water absorption rate of the recycled aggregate, therefore, the bare concrete produced by adopting the recycled aggregate is easy to ensure that the bare concrete has higher water absorption rate, the bare concrete is exposed in the external environment under the condition without other decorations, and when raining occurs, the bare concrete produced by adopting the recycled aggregate is easy to absorb a large amount of rainwater.
Because of the high industrialization degree of modern society, the acid rain condition is serious due to the combustion of automobile exhaust and sulfur-containing substances, and the acid rain contains Cl-、SO4 2-、NO3 -Ions and the like, the bare concrete produced by adopting the recycled aggregate can accelerate acid radical ions in acid rain to permeate into the internal structure of the concrete due to the self water absorption effect, the concrete is alkaline, and acid radical ions can generate acid-base neutralization reaction after entering the internal structure of the concrete, so that the alkali content in the concrete is reduced, the internal structure of the concrete is loose, and the strength of the bare concrete is influenced.
Disclosure of Invention
In order to avoid the acid radical ion in the excessive absorption acid rain of regeneration coarse aggregate for during acid radical ion gets into concrete inner structure, reduce the alkali content in the concrete, influence the intensity of clear water concrete, the application provides the clear water concrete of building rubbish regeneration aggregate production.
The application provides a bare concrete of construction waste recycled aggregate production adopts following technical scheme:
the fair-faced concrete produced by the construction waste recycled aggregate is prepared from the following raw materials in parts by weight: 420 parts of cement 360-fold, 42-65 parts of fly ash, 15-28 parts of mineral powder, 730 parts of river sand 710-fold, 1200 parts of modified recycled coarse aggregate 1100-fold, 5.6-7.8 parts of admixture, 5-8.6 parts of composite fiber and 180 parts of water 150-fold;
the modified recycled coarse aggregate is prepared by the following method:
i, pretreating waste concrete to prepare recycled coarse aggregate, weighing 20-35 parts of modified acrylate emulsion, and spraying the modified acrylate emulsion on the surface of 90-110 parts of recycled coarse aggregate to prepare primary coated recycled coarse aggregate;
II, weighing 32-40 parts of modified diatomite, spraying the modified diatomite on the surface of the primary coated recycled coarse aggregate prepared in the step I, and drying to prepare a semi-finished recycled coarse aggregate;
and III, weighing 42-55 parts of chitosan film liquid, spraying the chitosan film liquid on the surface of the semi-finished product recycled coarse aggregate prepared in the step II, and drying to prepare the modified recycled coarse aggregate.
Through adopting above-mentioned technical scheme, modified regeneration coarse aggregate cooperatees with composite fiber, reduces the hole of concrete inner structure through the filling effect to store the effect through collecting the acid radical ion in the acid rain, avoid acid radical ion in the acid rain to react with the alkali aggregate in the concrete, influence the intensity of concrete.
The acrylic ester emulsion, the modified diatomite and the chitosan membrane are matched, the acrylic ester emulsion is coated on the surface of the regenerated coarse aggregate, the modified diatomite particles are coated on the surface of the regenerated coarse aggregate by utilizing the better bonding effect of the acrylic ester emulsion, the surface of the regenerated coarse aggregate is coated with the chitosan membrane liquid, and the chitosan membrane liquid is cured into the chitosan membrane after being dried; when acid rain contacts with the bare concrete, the chitosan membrane attracts acid radical ions to move towards the modified regenerated coarse aggregate, the acid rain gradually destroys the coating effect of the chitosan membrane, so that the acid rain contacts with the modified diatomite, the modified diatomite absorbs the acid rain by utilizing the strong water absorption effect of the modified diatomite, the acid radical ions in the acid rain are absorbed, and the acid radical ions in the acid rain are matched with the absorption effect of the modified diatomite through the electrostatic attraction of the chitosan membrane, so that the acid radical ions in the acid rain are well stored after entering the concrete, and the acid radical ions in the acid rain are prevented from reacting with the alkali aggregate in the concrete to influence the strength of the concrete.
Preferably, the modified acrylate emulsion is prepared by the following method:
weighing 26-34 parts of water, 0.6-0.8 part of fatty alcohol-polyoxyethylene ether and 0.4-0.6 part of lauryl sodium sulfate, mixing and stirring for 10-15min, adding 9.7-10.2 parts of methyl methacrylate, 7.4-7.8 parts of butyl acrylate and 7.2-7.5 parts of isooctyl acrylate, emulsifying at 45-58 ℃ for 25-35min, adding 0.2-0.5 part of initiator, and reacting at 75-85 ℃ for 1-3h to prepare seed emulsion; weighing 9.7-10.2 parts of methyl methacrylate, 7.4-7.8 parts of butyl acrylate, 7.2-7.5 parts of isooctyl acrylate, 3.8-4.2 parts of dodecafluoroheptyl methacrylate, 1.3-1.6 parts of tetramethyltetravinylcyclotetrasiloxane and 0.2-0.5 part of initiator, mixing and stirring, dropwise adding the mixture into the seed emulsion prepared in the step (I), and reacting for 1-3 hours at the temperature of 75-85 ℃ to prepare the modified acrylate emulsion.
By adopting the technical scheme, the modified recycled coarse aggregate with stronger hydrophobic effect is prepared by adopting an emulsion polymerization method and taking acrylic ester as a main monomer and dodecafluoroheptyl methacrylate and tetramethyltetravinylcyclotetrasiloxane as functional monomers; the mechanical property of the acrylate emulsion film can be improved, the tensile strength and the elongation at break of the acrylate emulsion film are improved, the acrylate emulsion has high viscosity, and the acrylate emulsion can be tightly attached to the surface of the recycled coarse aggregate and can firmly bond the modified diatomite particles to the surface of the recycled coarse aggregate, so that the bonding effect of the modified diatomite is improved.
Preferably, the modified diatomite is prepared by the following method:
weighing 30-45 parts of diatomite, placing the diatomite into 65-80 parts of silver nitrate solution with the mass fraction of 2%, ultrasonically dispersing for 15-20min, taking out the diatomite, and drying at room temperature to obtain the modified diatomite.
By adopting the technical scheme, the diatomite is placed in the silver nitrate solution andultrasonic dispersion is carried out, so that silver nitrate enters the pore structure of the diatomite and Cl in acid rain-Cl as water molecules enter the internal pores of diatomaceous earth-Reacting with silver nitrate to obtain silver chloride precipitate, wherein the silver chloride precipitate is deposited in the inner pores of the diatomite, and SO is4 2-The silver sulfate precipitate is generated by reaction with silver nitrate, and acid radical ions in acid rain are collected and stored by utilizing the better adsorption effect of diatomite to match with the better precipitate storage effect, so that the influence of the acid radical ions on the concrete strength is avoided.
The silver nitrate solution is also attached to the surface of the modified diatomite, the modified diatomite particles are bonded to the surface of the modified acrylate emulsion film, a certain distance and a certain pore exist between the modified diatomite particles and the particles, the space position storage can be provided for precipitation, the regenerated coarse aggregate coated with the modified acrylate emulsion can be effectively isolated from acid rain by utilizing the filling effect of the precipitation, the acid rain is prevented from contacting the modified acrylate emulsion, and the surface of the regenerated coarse aggregate is prevented from absorbing the acid rain.
Preferably, the chitosan film solution is prepared by the following method:
weighing 1-3 parts of chitosan, placing the chitosan into 75-85 parts of acetic acid solution with mass fraction of 2%, and stirring and mixing to obtain the chitosan film solution.
Through adopting above-mentioned technical scheme, make chitosan membrane liquid with chitosan dissolution in acetic acid solution, contain amino in the chitosan, can produce the electrostatic attraction effect to the acid radical ion in the acid rain, the guide effect of cooperation composite fiber is convenient for shift acid radical ion to and modified diatomaceous earth mutually contact, utilize the collection of modified diatomaceous earth to store the effect, collect the processing to the acid radical ion in the acid rain, avoid the acid radical ion in the acid rain to influence the basicity of fair-faced concrete to avoid influencing the intensity of fair-faced concrete.
Preferably, the composite fiber consists of polypropylene fiber and steel fiber in the weight ratio of 1 (0.5-1).
By adopting the technical scheme, the polypropylene fiber and the steel fiber are matched to generate the functions of conduction and drainage on acid radical ions in acid rain, so that the acid rain is conveniently contacted with the modified recycled coarse aggregate, and the modified recycled coarse aggregate can collect and treat the acid radical ions in the acid rain; the polypropylene fiber has a good water conduction effect and is acid and alkali resistant, the steel fiber has a good conduction effect, and the migration of electrons can be promoted, so that the efficiency of acid radical ions in acid rain moving towards the modified recycled coarse aggregate is improved.
Preferably, the pretreatment in step i comprises the following steps: primary crushing, screening, cleaning, drying, secondary crushing, screening, cleaning and drying.
By adopting the technical scheme, the waste concrete is subjected to primary crushing to be primarily crushed into aggregate with smaller particles, after cleaning, slurry on the surface of the aggregate can be removed, and after drying, fine cracks on the surface of the aggregate are reduced, so that the water absorption of the aggregate is reduced; and then carrying out secondary crushing to ensure that the aggregate can be crushed to the added particle size of the coarse aggregate, then washing and drying again to reduce the water absorption of the aggregate, and screening and grading to prepare the coarse aggregate with lower water absorption so as to avoid the influence on the strength of the fair-faced concrete caused by more water absorption of the recycled coarse aggregate.
Preferably, the admixture consists of a polycarboxylic acid water reducing agent and sugar calcium in a weight ratio of 1 (0.3-0.8).
By adopting the technical scheme, the polycarboxylate superplasticizer is matched with the calcium saccharate to achieve a good water reducing effect; the polycarboxylate superplasticizer is matched with the modified recycled coarse aggregate, the polycarboxylate superplasticizer can form a hydrophobic film on the surface of cement particles, and the coated cement particles can generate electrostatic attraction with the modified recycled aggregate, so that the cement particles can be better bonded with the modified recycled aggregate; the calcium saccharate and the composite fiber are matched, so that the composite fiber is tightly bonded in the internal structure of the concrete, and the pores of the internal structure of the concrete can be reduced by matching the filling effect of the fly ash and the mineral powder, so that the water absorption condition of the internal structure of the concrete is reduced.
Preferably, the initiator in the step (i) is one or more of potassium persulfate, sodium persulfate and ammonium persulfate.
By adopting the technical scheme, the potassium persulfate, the sodium persulfate and the ammonium persulfate are selected as the initiator, so that the processing efficiency of the modified acrylate emulsion is improved conveniently.
In summary, the present application has the following beneficial effects:
1. the polypropylene fiber, the steel fiber, the acrylate emulsion, the modified diatomite and the chitosan membrane are matched in liquid phase, the better conduction effect of the polypropylene fiber and the steel fiber is matched with the better electrostatic attraction effect of the chitosan, so that acid radical ions in acid rain move towards the surface close to the modified regenerated coarse aggregate, the acid radical ions in the acid rain gradually damage the chitosan membrane, the acid radical ions are gradually contacted with the modified diatomite, the surface and the inner pores of the modified diatomite both contain silver ions, and the silver ions and the Cl are gradually contacted with the modified diatomite-And SO4 2-The reaction generates the sediment, the gaps among the modified diatomite surface particles provide space storage effect for the sediment, and the internal pores of the modified diatomite can store the sediment, so that acid ions in acid rain can generate the sediment to be stored, and the influence of the acid ions on the mechanical strength of the acid ions in the internal structure of the fair-faced concrete is avoided.
2. The chitosan film is alkaline, the chitosan film cannot be damaged in the mixing process of the fair-faced concrete and the curing process of the fair-faced concrete, and the chitosan film can attract the cement particles coated with the additives, so that the connection effect of the regenerated coarse aggregate and the cement particles is improved, the internal structure of the fair-faced concrete is compact, and acid rain is prevented from entering the internal structure of the fair-faced concrete.
3. After the surface of the recycled coarse aggregate is subjected to twice coating and once cladding, the bonding effect between the recycled coarse aggregate and cement particles is improved, the water absorption of the surface of the recycled coarse aggregate is reduced, and the strength of the fair-faced concrete is improved.
Detailed Description
The present application will be described in further detail with reference to examples.
Preparation example of modified acrylate emulsion
Sodium dodecyl sulfate, fatty alcohol-polyoxyethylene ether, methacrylic acid, butyl acrylate, isooctyl acrylate, dodecafluoroheptyl methacrylate, tetramethyltetravinylcyclotetrasiloxane, sodium persulfate, potassium persulfate and ammonium persulfate in the following raw materials are all sold in the ordinary market and are all analytically pure.
Preparation example 1: the modified acrylate emulsion is prepared by the following method:
weighing 30kg of water, 0.75kg of fatty alcohol-polyoxyethylene ether and 0.5kg of lauryl sodium sulfate, mixing, stirring at the rotating speed of 300r/min for 12min, adding 10.02kg of methyl methacrylate, 7.69kg of butyl acrylate and 7.37kg of isooctyl acrylate, emulsifying at the temperature of 50 ℃ for 30min, then dropwise adding 0.32kg of potassium persulfate, gradually heating to 80 ℃ after dropwise adding, and reacting at the temperature of 80 ℃ for 2h to prepare seed emulsion;
weighing 10.02kg of methyl methacrylate, 7.69kg of butyl acrylate, 7.37kg of isooctyl acrylate, 4kg of dodecafluoroheptyl methacrylate, 1.45kg of tetramethyltetravinylcyclotetrasiloxane and 0.32kg of potassium persulfate, mixing, and stirring at the rotating speed of 300r/min for 12min to prepare a mixed solution;
thirdly, dropwise adding the mixed solution prepared in the second step into the seed emulsion prepared in the first step, finishing the dropwise adding within 1h, then reacting for 2h at the temperature of 80 ℃, and cooling to room temperature to prepare the modified acrylate emulsion.
Preparation example 2: the modified acrylate emulsion is prepared by the following method:
weighing 26kg of water, 0.6kg of fatty alcohol-polyoxyethylene ether and 0.4kg of lauryl sodium sulfate, mixing, stirring for 10min at the rotating speed of 300r/min, adding 9.7kg of methyl methacrylate, 7.4kg of butyl acrylate and 7.2kg of isooctyl acrylate, emulsifying for 35min at the temperature of 45 ℃, then dropwise adding 0.2kg of sodium persulfate, gradually heating to 75 ℃ after dropwise adding, and reacting for 3h at the temperature of 75 ℃ to prepare seed emulsion;
weighing 9.7kg of methyl methacrylate, 7.4kg of butyl acrylate, 7.2kg of isooctyl acrylate, 3.8kg of dodecafluoroheptyl methacrylate, 1.3kg of tetramethyltetravinylcyclotetrasiloxane and 0.2kg of potassium persulfate, mixing, and stirring at the rotating speed of 300r/min for 12min to prepare a mixed solution;
thirdly, dropwise adding the mixed solution prepared in the second step into the seed emulsion prepared in the first step, finishing the dropwise adding within 1h, then reacting for 3h at the temperature of 75 ℃, and cooling to room temperature to prepare the modified acrylate emulsion.
Preparation example 3: the modified acrylate emulsion is prepared by the following method:
weighing 34kg of water, 0.8kg of fatty alcohol-polyoxyethylene ether and 0.6kg of lauryl sodium sulfate, mixing, stirring for 15min at the rotating speed of 300r/min, adding 10.2kg of methyl methacrylate, 7.8kg of butyl acrylate and 7.5kg of isooctyl acrylate, emulsifying for 25min at the temperature of 58 ℃, then dropwise adding 0.5kg of sodium persulfate, gradually heating to 85 ℃ after dropwise adding, and reacting for 1h at the temperature of 85 ℃ to prepare seed emulsion;
weighing 10.2kg of methyl methacrylate, 7.8kg of butyl acrylate, 7.5kg of isooctyl acrylate, 4.2kg of dodecafluoroheptyl methacrylate, 1.6kg of tetramethyltetravinylcyclotetrasiloxane and 0.5kg of ammonium persulfate, mixing, and stirring at the rotating speed of 300r/min for 12min to prepare a mixed solution;
thirdly, dropwise adding the mixed solution prepared in the second step into the seed emulsion prepared in the first step, finishing the dropwise adding within 1 hour, then reacting for 1 hour at the temperature of 85 ℃, and cooling to room temperature to prepare the modified acrylate emulsion.
Preparation example of modified diatomaceous earth
The diatomaceous earth used in the following raw materials was purchased from Shunhuan chemical technology Co., Ltd, model 06, having a specific surface area of 2m2(ii)/g; silver nitrate is a commercial analytical grade; other raw materials and equipment are all sold in the market.
Preparation example 4: weighing 38kg of diatomite, placing the diatomite in 72kg of silver nitrate solution with the mass fraction of 2%, ultrasonically dispersing for 18min under the condition of 20kHz, taking out the diatomite, and drying at room temperature to obtain the modified diatomite.
Preparation example 5: weighing 30kg of diatomite, placing the diatomite in 65kg of silver nitrate solution with the mass fraction of 2%, ultrasonically dispersing for 15min under the condition of 20kHz, taking out the diatomite, and drying at room temperature to obtain the modified diatomite.
Preparation example 6: weighing 45kg of diatomite, placing the diatomite in 80kg of silver nitrate solution with the mass fraction of 2%, ultrasonically dispersing for 20min under the condition of 20kHz, taking out the diatomite, and drying at room temperature to obtain the modified diatomite.
Preparation example of Chitosan Membrane liquid
The chitosan in the following raw materials is purchased from Qingdao Heisen Biotech limited, and the content of effective substances is 99 percent; other raw materials and equipment are all sold in the market.
Preparation example 7: the chitosan film liquid is prepared by the following method:
weighing 2kg of chitosan, placing the chitosan into 80kg of acetic acid solution with the mass fraction of 2%, and stirring for 16min at the rotating speed of 800r/min to obtain the chitosan film liquid.
Preparation example 8: the chitosan film liquid is prepared by the following method:
weighing 1kg of chitosan, placing the chitosan into 75kg of acetic acid solution with the mass fraction of 2%, and stirring for 12min at the rotating speed of 800r/min to obtain the chitosan film liquid.
Preparation example 9: the chitosan film liquid is prepared by the following method:
3kg of chitosan is weighed and placed in 85kg of acetic acid solution with the mass fraction of 2%, and the chitosan film solution is prepared after stirring for 18min at the rotating speed of 800 r/min.
Preparation example of modified recycled coarse aggregate
The following raw materials and equipment were all commercially available.
Preparation example 10: the modified recycled coarse aggregate is prepared by the following method:
i, performing primary crushing treatment on waste concrete, screening to obtain broken blocks with the particle size of 40-70mm, washing for 2 times after screening, and drying for 2 hours at 350 ℃ to obtain bone blocks; carrying out secondary crushing on the prepared aggregate blocks, screening and cleaning for 2 times, and then drying for 2 hours at 350 ℃ to obtain recycled coarse aggregate with the particle size of 5-15 mm;
II, weighing 28kg of the modified acrylate emulsion prepared in the preparation example 1, and spraying the modified acrylate emulsion on the surface of 100kg of the recycled coarse aggregate prepared in the step I to prepare a primary coated recycled coarse aggregate; weighing 36kg of the modified diatomite prepared in preparation example 4, spraying the modified diatomite on the surface of the primary coated recycled coarse aggregate, drying the primary coated recycled coarse aggregate for 2 hours at the temperature of 28 ℃, and curing the modified acrylate emulsion into a modified acrylate film to prepare a semi-finished product recycled coarse aggregate;
III, weighing 48kg of chitosan membrane liquid prepared in preparation example 7, spraying the chitosan membrane liquid on the surface of the semi-finished product regenerated coarse aggregate prepared in the step II, drying the obtained product for 2 hours at the temperature of 28 ℃, and solidifying the chitosan membrane liquid into a chitosan membrane to obtain the modified regenerated coarse aggregate.
Preparation example 11: the modified recycled coarse aggregate is prepared by the following method:
i, performing primary crushing treatment on waste concrete, screening to obtain broken blocks with the particle size of 40-70mm, washing for 2 times after screening, and drying for 2 hours at 350 ℃ to obtain bone blocks; carrying out secondary crushing on the prepared aggregate blocks, screening and cleaning for 2 times, and then drying for 2 hours at 350 ℃ to obtain recycled coarse aggregate with the particle size of 5-15 mm;
II, weighing 20kg of the modified acrylate emulsion prepared in the preparation example 2, and spraying the modified acrylate emulsion on the surface of 90kg of the recycled coarse aggregate prepared in the step I to prepare a primary coated recycled coarse aggregate; weighing 32kg of the modified diatomite prepared in preparation example 5, spraying the modified diatomite on the surface of the primary coated recycled coarse aggregate, drying the primary coated recycled coarse aggregate for 2 hours at the temperature of 28 ℃, and curing the modified acrylate emulsion into a modified acrylate film to prepare a semi-finished product recycled coarse aggregate;
III 42kg of chitosan membrane liquid prepared in preparation example 8 is weighed and sprayed on the surface of the semi-finished product regenerated coarse aggregate prepared in II, the semi-finished product regenerated coarse aggregate is dried for 2 hours at the temperature of 28 ℃, and the chitosan membrane liquid is solidified into a chitosan membrane, so that the modified regenerated coarse aggregate is prepared.
Preparation example 12: the modified recycled coarse aggregate is prepared by the following method:
i, performing primary crushing treatment on waste concrete, screening to obtain broken blocks with the particle size of 40-70mm, washing for 2 times after screening, and drying for 2 hours at 350 ℃ to obtain bone blocks; carrying out secondary crushing on the prepared aggregate blocks, screening and cleaning for 2 times, and then drying for 2 hours at 350 ℃ to obtain recycled coarse aggregate with the particle size of 5-15 mm;
II, weighing 35kg of the modified acrylate emulsion prepared in the preparation example 3, and spraying the modified acrylate emulsion on the surface of 110kg of the recycled coarse aggregate prepared in the step I to prepare a primary coated recycled coarse aggregate; weighing 40kg of the modified diatomite prepared in preparation example 6, spraying the modified diatomite on the surface of the primary coated recycled coarse aggregate, drying the primary coated recycled coarse aggregate for 2 hours at the temperature of 28 ℃, and curing the modified acrylate emulsion into a modified acrylate film to prepare a semi-finished product recycled coarse aggregate;
III, weighing 55kg of chitosan membrane liquid prepared in preparation example 9, spraying the chitosan membrane liquid on the surface of the semi-finished product regenerated coarse aggregate prepared in the step II, drying the obtained product for 2 hours at the temperature of 28 ℃, and solidifying the chitosan membrane liquid into a chitosan membrane to obtain the modified regenerated coarse aggregate.
Examples
The cement in the following raw materials is purchased from P.O42.5 Portland cement produced by Qingdao mountain and river Innovative Cement Co Ltd; the slag powder is purchased from S95 level mineral powder produced by Qingdao Mitsu-Mitsui Kongmai Kogyo; the fly ash is purchased from Xingyuan mineral powder processing factories in Lingshou county; river sand is purchased from Yitian mineral products Co., Ltd, Shijiazhuang; polypropylene fibers were purchased from the Beijing Pengyang New building materials, Inc.; the steel fiber is purchased from the shearing wave-shaped steel fiber produced by Hebei Dingyuan engineering rubber Co Ltd; the polycarboxylic acid water reducing agent is purchased from Panjin Fulong chemical company, Inc.; the sugar calcium is purchased from Shandong Weifang public trust industry trade company; other raw materials and equipment are all sold in the market.
Example 1: the clear water concrete produced by the construction waste recycled aggregate comprises the following components:
the raw materials are as follows: 380kg of cement, 57kg of fly ash, 22kg of mineral powder, 724kg of river sand, 1155kg of modified recycled coarse aggregate prepared in preparation example 10, 6.5kg of additive, 7.2kg of composite fiber and 165kg of water; the composite fiber consists of polypropylene fiber and steel fiber in the weight ratio of 1: 0.8; the admixture consists of a polycarboxylic acid water reducing agent and sugar calcium in a weight ratio of 1: 0.5.
Example 2: the clear water concrete produced by the construction waste recycled aggregate comprises the following components:
the raw materials are as follows: 360kg of cement, 42kg of fly ash, 15kg of mineral powder, 710kg of river sand, 1100kg of modified recycled coarse aggregate prepared in preparation example 11, 5.6kg of additive, 5kg of composite fiber and 150kg of water; the composite fiber consists of polypropylene fiber and steel fiber in the weight ratio of 1: 0.5; the admixture consists of a polycarboxylic acid water reducing agent and sugar calcium in a weight ratio of 1: 0.3.
Example 3: the clear water concrete produced by the construction waste recycled aggregate comprises the following components:
the raw materials are as follows: 420kg of cement, 65kg of fly ash, 28kg of mineral powder, 730kg of river sand, 1200kg of modified regenerated coarse aggregate prepared in preparation example 12, 7.8kg of additive, 8.6kg of composite fiber and 180kg of water; the composite fiber consists of polypropylene fiber and steel fiber in a weight ratio of 1: 1; the admixture consists of a polycarboxylic acid water reducing agent and sugar calcium in a weight ratio of 1: 0.8.
The slag powder in the raw materials is S95 grade slag powder with the density of 2.8g/cm3Specific surface area of 400m2The activity index (7d) is more than or equal to 85 percent, the activity index (28d) is more than or equal to 96 percent, the fluidity ratio is more than or equal to 94 percent, and the water content is less than or equal to 0.2 percent; the fly ash is F class II fly ash, the fineness of the fly ash (45 mu m square hole sieve residue)<10% water demand ratio<100% loss on ignition<6% water content<0.2 percent; river sand with fineness modulus of 2.4 and apparent density of 2650kg/m3。
Note: the additives in the raw materials include but are not limited to polycarboxylic acid water reducing agent and sugar calcium.
Application example: a preparation method of fair-faced concrete produced by construction waste recycled aggregate comprises the following steps:
s1, weighing cement, fly ash, mineral powder, river sand and water, and mixing to obtain a mixture;
s2, weighing the polypropylene fibers and the steel fibers, stirring for 5min at the rotating speed of 300r/min to prepare composite fibers, weighing the modified recycled coarse aggregate, the admixture and the composite fibers, adding the mixture prepared in the S1, mixing and stirring, pouring the mixture into a mold, and curing to obtain the finished product of the fair-faced concrete.
Comparative example
Comparative example 1: the difference between the embodiment and the embodiment 1 is that the modified recycled coarse aggregate is prepared by the following method:
and I, crushing the waste concrete to obtain recycled coarse aggregate with the particle size of 5-15 mm.
Comparative example 2: the comparative example is different from example 1 in that the modified recycled coarse aggregate is prepared by the following method:
II, weighing 36kg of the modified diatomite prepared in the preparation example 4, spraying the modified diatomite on the surface of the recycled coarse aggregate, and drying the obtained product for 2 hours at the temperature of 28 ℃ to obtain a semi-finished recycled coarse aggregate.
Comparative example 3: the comparative example is different from example 1 in that the modified recycled coarse aggregate is prepared by the following method:
II, weighing 28kg of the modified acrylate emulsion prepared in the preparation example 1, spraying the modified acrylate emulsion on the surface of 100kg of the recycled coarse aggregate prepared in the preparation example I, drying the mixture for 2 hours at the temperature of 28 ℃, and curing the modified acrylate emulsion into a modified acrylate film to prepare a semi-finished recycled coarse aggregate.
Comparative example 4: the comparative example is different from example 1 in that the modified recycled coarse aggregate is prepared by the following method:
II, weighing 28kg of the modified acrylate emulsion prepared in the preparation example 1, and spraying the modified acrylate emulsion on the surface of 100kg of the recycled coarse aggregate prepared in the step I to prepare a primary coated recycled coarse aggregate; weighing 36kg of diatomite, spraying the diatomite on the surface of the primary coated recycled coarse aggregate, drying for 2h at the temperature of 28 ℃, and curing the modified acrylate emulsion into a modified acrylate film to obtain a semi-finished recycled coarse aggregate.
Comparative example 5: the comparative example is different from example 1 in that the modified recycled coarse aggregate is prepared by the following method:
II, weighing 28kg of the modified acrylate emulsion prepared in the preparation example 1, and spraying the modified acrylate emulsion on the surface of 100kg of the recycled coarse aggregate prepared in the step I to prepare a primary coated recycled coarse aggregate; and weighing 36kg of the modified diatomite prepared in preparation example 4, spraying the modified diatomite on the surface of the primary coating recycled coarse aggregate, drying the primary coating recycled coarse aggregate for 2 hours at the temperature of 28 ℃, and curing the modified acrylate emulsion into a modified acrylate film to obtain the modified recycled concrete.
Comparative example 6: the present embodiment is different from embodiment 1 in that: the polypropylene fiber is replaced by the same mass of steel fiber in the raw material.
Performance test
The raw material proportions of the examples 1-3 and the comparative examples 1-6 are respectively adopted to prepare the finished product as-cast finish concrete standard test block.
1. Detection of compressive strength properties
And (3) manufacturing a standard test block according to GB/T50081-2019 standard of mechanical property test method of common concrete, and measuring the compressive strength of the standard test block for curing for 7d and 28 d.
2. Flexural strength Property measurement
And (3) manufacturing a standard test block according to GB/T50081-2019 standard of mechanical property test method of common concrete, and measuring the flexural strength of the standard test block for 7d and 28d of maintenance.
3. Detection of water permeation resistance
And testing the water permeation resistance pressure of the standard test block according to GB/T50082-2019 Standard test method for the long-term performance and durability of the common concrete.
4. Detection of chloride ion permeation resistance
And testing the chloride ion penetration depth of the standard test block according to a rapid chloride ion migration coefficient method in GB/T50082-2019 'test method standard of long-term performance and durability of common concrete'.
Table 1 testing table for testing performance of fair-faced concrete
Although the fair-faced concrete prepared in the embodiments 1 to 3 of the application has the problems of water seepage and chloride ion permeation, the influence on the concrete self that the concrete has higher compressive strength and bending strength is avoided, which indicates that the modified and regenerated coarse aggregate prepared in the application has a good collecting and treating effect on chloride ions, and the influence on the mechanical strength of the fair-faced concrete caused by the movement of the chloride ions in the internal structure of the fair-faced concrete is avoided.
By combining examples 1-3 and comparative examples 1-6 and combining table 1, it can be seen that in comparative example 1, when the fair-faced concrete is prepared, the waste concrete is not cleaned and dried, and compared with example 1, the compressive strength, the flexural strength, the water seepage resistance effect and the chloride ion permeation resistance effect of the fair-faced concrete prepared in comparative example 1 are all smaller than those of example 1; the number of the fine cracks on the surface of the cleaned and dried recycled coarse aggregate is obviously reduced, so that the water absorption of the recycled coarse aggregate is reduced, and the influence of the bare concrete prepared from the recycled coarse aggregate on the mechanical strength of the finished product bare concrete is avoided.
Comparative example 2 when preparing the modified recycled coarse aggregate, the surface of the recycled coarse aggregate is not sprayed with the modified acrylate emulsion, and comparative example 3 when preparing the modified recycled coarse aggregate, the surface of the recycled coarse aggregate is not sprayed with the modified diatomite, compared with example 1, the compression strength, the breaking strength, the water seepage resistance effect and the chloride ion permeation resistance effect of the fair-faced concrete prepared in comparative examples 2 and 3 are all smaller than those of example 1; the modified polyacrylic acid emulsion and the modified diatomite are matched, so that the modified diatomite is uniformly attached to the surface of the modified acrylate emulsion, the modified diatomite is attached to the surface of the regenerated coarse aggregate, and the chlorine ions are collected and treated by utilizing the hydrophobicity of the modified polyacrylic acid emulsion and the good water absorbability of the modified diatomite, so that the regenerated coarse aggregate is prevented from excessively absorbing water, and the chlorine ions are prevented from moving in the fair-faced concrete to influence the mechanical strength of the fair-faced concrete.
Comparative example 4 when the modified recycled coarse aggregate is prepared, the diatomite is not modified, that is, no silver ions exist on the surface and in the internal pore structure of the diatomite, and compared with example 1, the compression strength, the breaking strength, the water seepage resistance effect and the chlorine ion permeation resistance effect of the fair-faced concrete prepared in comparative example 4 are all smaller than those of example 1; the method has the advantages that silver ions attached to the surface and the internal structure of the diatomite can react with chloride ions, so that the chloride ions are precipitated, the chloride ions are collected and treated, and the phenomenon that the chloride ions move in the internal structure of the fair-faced concrete to influence the mechanical strength of the fair-faced concrete is avoided.
Comparative example 5 when the modified recycled coarse aggregate is prepared, the chitosan film is not coated on the surface of the modified recycled coarse aggregate, and compared with example 1, the compression strength, the breaking strength, the water seepage resistance effect and the chloride ion permeation resistance effect of the fair-faced concrete prepared in comparative example 5 are all smaller than those of example 1; the chitosan membrane, the modified diatomite and the composite fiber are matched, the chitosan is matched with the electrostatic attraction effect of chitosan on chloride ions through the conduction effect of the composite fiber, so that the chloride ions are in contact with the modified diatomite, and the chloride ions are prevented from moving in the internal structure of the fair-faced concrete and influencing the mechanical strength of the fair-faced concrete by utilizing the absorption treatment effect of the modified diatomite on the chloride ions.
Comparative example 6 when fair-faced concrete is prepared, the polypropylene fiber is replaced by the steel fiber with the same mass in the raw materials, and compared with example 1, the compressive strength, the breaking strength, the water seepage resistance effect and the chloride ion permeation resistance effect of the fair-faced concrete prepared in the comparative example 6 are all smaller than those of the concrete prepared in the example 1; the polypropylene fiber and the steel fiber are matched, so that the mechanical strength of the fair-faced concrete can be improved through the filling effect, the conduction effect can be provided for chloride ions, the chloride ions are accelerated to move towards the surface of the modified and regenerated coarse aggregate, and the chloride ions can be well collected and treated by utilizing the higher addition amount of the modified and regenerated coarse aggregate, so that the mechanical strength of the fair-faced concrete is prevented from being influenced.
The present embodiment is only for explaining the present application, and it is not limited to the present application, 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 application.
Claims (6)
1. The fair-faced concrete produced by the construction waste recycled aggregate is characterized by being prepared from the following raw materials in parts by weight: 420 parts of cement 360-fold, 42-65 parts of fly ash, 15-28 parts of mineral powder, 730 parts of river sand 710-fold, 1200 parts of modified recycled coarse aggregate 1100-fold, 5.6-7.8 parts of admixture, 5-8.6 parts of composite fiber and 180 parts of water 150-fold;
the modified recycled coarse aggregate is prepared by the following method:
i, pretreating waste concrete to prepare recycled coarse aggregate, weighing 20-35 parts by weight of modified acrylate emulsion, and spraying the modified acrylate emulsion on the surface of 90-110 parts by weight of recycled coarse aggregate to prepare primary coated recycled coarse aggregate;
II, weighing 32-40 parts by weight of modified diatomite, spraying the modified diatomite on the surface of the primary coated recycled coarse aggregate prepared in the step I, and drying to prepare a semi-finished recycled coarse aggregate;
III, weighing 42-55 parts by weight of chitosan film liquid, spraying the chitosan film liquid on the surface of the semi-finished product recycled coarse aggregate prepared in the step II, and drying to prepare modified recycled coarse aggregate;
the modified diatomite is prepared by the following method:
weighing 30-45 parts by weight of diatomite, placing the diatomite into 65-80 parts by weight of silver nitrate solution with the mass fraction of 2%, ultrasonically dispersing for 15-20min, taking out the diatomite, and drying at room temperature to obtain modified diatomite;
the modified acrylate emulsion is prepared by the following method:
weighing 26-34 parts by weight of water, 0.6-0.8 part by weight of fatty alcohol-polyoxyethylene ether and 0.4-0.6 part by weight of lauryl sodium sulfate, mixing and stirring for 10-15min, adding 9.7-10.2 parts by weight of methyl methacrylate, 7.4-7.8 parts by weight of butyl acrylate and 7.2-7.5 parts by weight of isooctyl acrylate, emulsifying at 45-58 ℃ for 25-35min, adding 0.2-0.5 part by weight of initiator, and reacting at 75-85 ℃ for 1-3h to obtain seed emulsion;
weighing 9.7-10.2 parts by weight of methyl methacrylate, 7.4-7.8 parts by weight of butyl acrylate, 7.2-7.5 parts by weight of isooctyl acrylate, 3.8-4.2 parts by weight of dodecafluoroheptyl methacrylate, 1.3-1.6 parts by weight of tetramethyltetravinylcyclotetrasiloxane and 0.2-0.5 part by weight of initiator, mixing and stirring, dropwise adding the mixture into the seed emulsion prepared in the step one, and reacting for 1-3 hours at the temperature of 75-85 ℃ to prepare the modified acrylate emulsion.
2. The fair-faced concrete produced from the construction waste recycled aggregate according to claim 1, which is characterized in that the chitosan film liquid is prepared by adopting the following method:
weighing 1-3 parts by weight of chitosan, placing the chitosan into 75-85 parts by weight of acetic acid solution with mass fraction of 2%, and stirring and mixing to obtain the chitosan film solution.
3. The fair-faced concrete produced from the construction waste recycled aggregate according to claim 1, wherein the composite fiber consists of polypropylene fiber and steel fiber in a weight ratio of 1: 0.5-1.
4. The fair-faced concrete produced by the construction waste recycled aggregate according to claim 1, wherein the pretreatment in the step I comprises the following steps: primary crushing, screening, cleaning, drying, secondary crushing, screening, cleaning and drying.
5. The fair-faced concrete produced by the construction waste recycled aggregate according to claim 1, wherein the additive consists of a polycarboxylic acid water reducing agent and calcium saccharate in a weight ratio of 1: 0.3-0.8.
6. The fair-faced concrete produced by the construction waste recycled aggregate according to the claim 1, wherein the initiator in the step (r) is one or more of potassium persulfate, sodium persulfate and ammonium persulfate.
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