CN112745072A - C25-35 recycled aggregate concrete for prefabricated building and design method thereof - Google Patents

C25-35 recycled aggregate concrete for prefabricated building and design method thereof Download PDF

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CN112745072A
CN112745072A CN202011615965.3A CN202011615965A CN112745072A CN 112745072 A CN112745072 A CN 112745072A CN 202011615965 A CN202011615965 A CN 202011615965A CN 112745072 A CN112745072 A CN 112745072A
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recycled aggregate
aggregate concrete
concrete
ratio
water
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陈培标
刘刚
张大财
霍金
朱卫东
金旺洲
刘万平
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Fujian Hongsheng Material Technology Co ltd
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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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00017—Aspects relating to the protection of the environment
    • 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
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  • Civil Engineering (AREA)
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  • Inorganic Chemistry (AREA)
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Abstract

The invention discloses C25-35 recycled aggregate concrete for fabricated buildings and a design method thereof, relating to the technical field of concrete, and the technical scheme is characterized by comprising the following components in parts by weight: 432 portions of gel material 320-; an aggregate composition 1735 parts; 3.2-10.4 parts of an additive; wherein the gel material comprises cement and mineral admixture in a weight ratio of 31-40:10-19, and the 28d compressive strength is not less than 27.4 MPa; the aggregate composition comprises primary sand and recycled aggregate according to the weight part ratio of 9: 11; the raw sand is natural sand and machine-made sand; the additive is a polycarboxylic acid high-performance water reducing agent. According to the invention, the recycled aggregate concrete is prepared by adopting the corresponding components in parts by weight, so that the recycled aggregate concrete with high mechanical and durability properties is obtained, and meanwhile, the effect of effectively utilizing and consuming recycled aggregate prepared from construction dismantling garbage is achieved.

Description

C25-35 recycled aggregate concrete for prefabricated building and design method thereof
Technical Field
The invention relates to the technical field of concrete, in particular to C25-35 recycled aggregate concrete for fabricated buildings and a design method thereof.
Background
The recycling of the construction waste is the foundation for realizing the recycling construction of urban ecology, and the biggest obstacle for preventing the recycling of the construction waste is that the construction disassembled waste product, namely recycled aggregate and the product thereof have poor performance and lack of scientific use basis and method. The recycled aggregate has poor working performance and mechanical property and elastic modulus far lower than that of the original aggregate concrete due to high water absorption, low firmness and non-uniformity of performances of different disassembled source products according to GJG-55 'design rules for mixing proportion of common concrete', so that the recycled aggregate is difficult to apply to stress parts of engineering structures.
Chinese patent application with publication number CN107382216A discloses a high-strength concrete doped with iron tailings and construction waste and a preparation method thereof, wherein the high-strength concrete comprises a multi-element gelling system, the iron tailings, stones, construction waste recycled aggregate and a water reducing agent, and each cubic meter of the high-strength concrete comprises 568.7kg-597.5kg of the multi-element gelling system, 413.9kg-430.8kg of the iron tailings, 807kg-1010.07kg of the stones, 150.93kg-371.52kg of the construction waste recycled aggregate, 8.8-9.4kg of the water reducing agent and 150.4kg-163kg of water; wherein the multielement gelling system comprises cement, fly ash, slag, silica fume and rice husk ash, and each cubic meter of the high-strength concrete comprises 268kg-279kg of cement, 87.1kg-91.9kg of fly ash, 174.2kg-183.8kg of slag, 28kg-29.9kg of silica fume and 11.4kg-12.9kg of rice husk ash.
However, the high-strength concrete and the preparation method thereof are too high in cost, so that the problem that the regeneration utilization rate of construction waste is low is difficult to solve, and the obtained high-strength concrete is poor in mechanical property and durability and needs to be improved.
Disclosure of Invention
Aiming at the defects in the prior art, the first purpose of the invention is to provide the C25-35 recycled aggregate concrete for the fabricated building, wherein the C25-35 recycled aggregate concrete for the fabricated building has the effect of remarkably improving the mechanical and durability performances of the recycled aggregate concrete.
In order to achieve the purpose, the invention provides the following technical scheme:
the C25-35 recycled aggregate concrete for the fabricated building is characterized by comprising the following components in parts by weight:
432 portions of gel material 320-;
an aggregate composition 1735 parts;
3.2-10.4 parts of an additive;
wherein the gel material comprises 31-40:10-19 parts by weight of cement and mineral admixture, and the 28d compressive strength is not less than 27.4 MPa; the aggregate composition comprises primary sand and recycled aggregate according to the weight part ratio of 9: 11; the additive is a polycarboxylic acid high-performance water reducing agent.
The invention is further configured to: the cement is P.O42.5-52.5; the mineral admixture is fly ash and mineral powder; and the fly ash is F class I-II; the mineral powder is in S95-105 grade.
The invention is further configured to: the raw sand is natural sand and machine-made sand, and the fineness modulus is 2.5-2.9; the minimum porosity of the recycled aggregate is 43.0%, and the water absorption is 2.3-6.5%.
The invention is further configured to: the minimum mixing amount water reducing rate of the polycarboxylic acid high-performance water reducing agent is 26%.
The invention is further configured to: the slump of the recycled aggregate concrete is 50-160 mm.
The second purpose of the application is to provide a design method of C25-35 recycled aggregate concrete for prefabricated buildings, which comprises the following steps:
step 1, determining the strength of recycled aggregate concrete, and calculating according to the following formula:
fcu.0≥fcu,k+1.645σ；
wherein: f. ofcu.0The value is the strength value of recycled aggregate concrete; f. ofcu,kThe standard value (MPa) of the cubic compressive strength of the recycled aggregate concrete; sigma is standard difference of strength of recycled aggregate concrete, and the value is 5.0;
step 2, determining the water-cement ratio of the recycled aggregate concrete, and calculating according to the following formula:
Figure BDA0002874910570000031
wherein:
Figure BDA0002874910570000032
the water-cement ratio of the recycled aggregate concrete is obtained; alpha is alphaaAnd alphabAre all regression coefficients, and αaValue of 0.53, alphabThe value is 0.20; f. ofbThe strength (MPa) of the gelled material 28d sand;
step 3, determining the aggregate composition dosage of the recycled aggregate concrete: obtaining the aggregate total dosage of the recycled aggregate concrete according to a stacking density test of the minimum void fraction, namely the dosage of the aggregate composition of 1735kg used per cubic meter, and calculating the required dosage of the raw sand and the recycled aggregate according to the weight part ratio of the raw sand to the recycled aggregate;
step 4, determining the water consumption of the recycled aggregate concrete, and calculating according to the following formula:
mw0＝mwo1(1-β)+mwo2；
wherein: m isw0The actual water consumption (kg/m) of each cubic of recycled aggregate concrete required by construction3)；mwo1The estimated water consumption (kg/m) per cubic meter of recycled aggregate concrete which meets the construction requirements when the water reducing agent is not blended3)；mwo2The aggregate water absorption mass (kg/m) of each cubic recycled aggregate concrete3) (ii) a Beta is the water reducing rate (%) of the water reducing agent;
and 5, determining the dosage of the gel material, and calculating according to the following formula:
Figure BDA0002874910570000041
wherein: b ism0The total cementing material dosage (kg/m) of cement and admixture for recycled aggregate concrete3) (ii) a And calculating the required weight ratio of cement to mineral admixtureThe amount of cement and mineral admixture;
and 6, determining the dosage of the additive, and calculating according to 1.9% of the dosage of the cementing material.
The invention is further configured to: after the amount of the gel material is determined through step 5, continuing to perform adjustment of the design mix ratio; the method for adjusting the design mixing ratio comprises the following steps:
s1, respectively increasing and decreasing by 0.05 according to the water-glue ratios obtained in the step 2 to form three water-glue ratios;
s2, continuing the steps 3 to 6 according to the three water-glue ratios obtained in the step S1, obtaining corresponding mixing ratios to adapt and mold a cubic compression-resistant test piece, testing the compression strength after 28d standard curing, and drawing a linear relation graph of the compression strength and the glue ratio;
s3, taking the glue ratio with higher configuration strength as the glue ratio of the design mixing ratio;
s4, continuing to judge, and if the calculated volume weight difference of the concrete volume weight ratio of the trial mix proportion to the design mix proportion is more than 2%, correcting the following formula:
Figure BDA0002874910570000051
wherein: m isw、mc、mf、mgAnd msRespectively the water, cement, fly ash and/or mineral powder, the raw sand and the recycled aggregate (kg/m) of the recycled aggregate concrete with the final mixing ratio3)；pc,tTo try out the measured value of the apparent density of the concrete (kg/m)3)；pc,cCalculated value (kg/m) of concrete mixing ratio3)。
The invention is further configured to: in the step 3, the weight part ratio of the raw sand to the recycled aggregate is 9: 11.
The invention is further configured to: in step 4, mwo1Based on the water consumption of 90mm slump, the slump is increased by 5kg/m for every 20mm3And calculating the water consumption.
The invention is further configured to: in step 5, the weight ratio of the cement to the mineral admixture is 31-40: 10-19.
In conclusion, the invention has the following beneficial effects:
1. by adopting the corresponding components in parts by weight to prepare the recycled aggregate concrete, the recycled aggregate prepared from construction dismantling garbage is effectively utilized and consumed while the recycled aggregate concrete with high mechanical and durability properties is obtained;
2. the recycled aggregate concrete designed and obtained by the design method can be used for the production and manufacture of assembly members such as assembly building enclosure walls, superposed floor slabs, stressed structure superposed secondary beams of multi-storey buildings and the like, and has wide market prospect;
3. the compressive strength, the elastic modulus and the durability of the recycled aggregate concrete are obviously improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a graph showing the relationship between the compressive strength of concrete and the ratio of glue in the first embodiment of the present application;
FIG. 2 is a graph showing the relationship between the compressive strength of concrete and the ratio of glue in example II of the present application;
fig. 3 is a graph showing the relationship between the compressive strength of concrete and the glue ratio in the third embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The concrete and the design method of the fabricated building C25-35 recycled aggregate concrete of the embodiment of the invention are specifically described as follows:
the C25-35 recycled aggregate concrete for the fabricated building comprises the following components in parts by weight:
432 portions of gel material 320-;
an aggregate composition 1735 parts;
3.2-10.4 parts of an additive;
wherein the gel material comprises 31-40:10-19 P.O42.5-52.5 cement and mineral admixture in parts by weight. Mineral admixtures include, but are not limited to, fly ash and mineral fines. The fly ash is F class I-II grade fly ash, the mineral powder is S95-105 grade, and the 28d compressive strength is not less than 27.4 MPa. The aggregate composition comprises primary sand and recycled aggregate according to the weight part ratio of 9:11, wherein the primary sand is natural sand and machine-made sand, and the fineness modulus is 2.5-2.9; the minimum porosity of the recycled aggregate is 43.0%, and the water absorption is 2.3-6.5%. The admixture is a polycarboxylic acid high-performance water reducing agent with the lowest doping amount and the water reducing rate of 26 percent.
And slump of recycled aggregate concrete obtained by the above components in parts by weight is 50-160 mm.
The application also provides a design method of the C25-35 recycled aggregate concrete for the fabricated building, which comprises the following steps:
step 1, determining the strength of recycled aggregate concrete, and calculating according to the following formula:
fcu.0≥fcu,k+1.645σ；
wherein: f. ofcu.0The value is the strength value of recycled aggregate concrete; f. ofcu,kThe standard value (MPa) of the cubic compressive strength of the recycled aggregate concrete; sigma is standard difference of strength of recycled aggregate concrete, and the value is 5.0;
step 2, determining the water-cement ratio of the recycled aggregate concrete, and calculating according to the following formula:
Figure BDA0002874910570000071
wherein:
Figure BDA0002874910570000072
the water-cement ratio of the recycled aggregate concrete is obtained; alpha is alphaaAnd alphabAre all regression coefficients, and αaValue of 0.53, alphabThe value is 0.20; f. ofbThe strength (MPa) of the gelled material 28d sand;
step 3, determining the aggregate composition dosage of the recycled aggregate concrete: obtaining the total aggregate dosage of the recycled aggregate concrete according to a stacking density test of the minimum void fraction, namely the aggregate composition dosage of 1735kg used per cubic meter, and calculating the required raw sand dosage and the required recycled aggregate dosage according to the weight part ratio of the raw sand to the recycled aggregate, namely 9: 11;
step 4, determining the water consumption of the recycled aggregate concrete, and calculating according to the following formula:
mw0＝mwo1(1-β)+mwo2；
wherein: m isw0The actual water consumption (kg/m) of each cubic of recycled aggregate concrete required by construction3)；mwo1The estimated water consumption (kg/m) per cubic meter of recycled aggregate concrete which meets the construction requirements when the water reducing agent is not blended3) And m iswo1Based on the water consumption of 90mm slump, the slump is increased by 5kg/m for every 20mm3Calculating the water consumption; m iswo2The aggregate water absorption mass (kg/m) of each cubic recycled aggregate concrete3) (ii) a Beta is the water reducing rate (%) of the water reducing agent;
and 5, determining the dosage of the gel material, and calculating according to the following formula:
Figure BDA0002874910570000081
wherein: b ism0The total cementing material dosage (kg/m) of cement and admixture for recycled aggregate concrete3) (ii) a Calculating the required dosage of the cement, the fly ash and the mineral powder according to the weight part ratio of the cement, the fly ash and the mineral powder, namely 31:9:10 or 3:1: 0;
step 6, determining the dosage of the additive, and calculating according to 1.9% of the dosage of the cementing material;
and 7, adjusting the design mixing ratio, wherein the adjusting method of the design mixing ratio comprises the following steps:
s1, respectively increasing and decreasing by 0.05 according to the water-glue ratios obtained in the step 2 to form three water-glue ratios;
s2, continuing the steps 3 to 6 according to the three water-glue ratios obtained in the step S1, obtaining corresponding mixing ratios to adapt and mold a cubic compression-resistant test piece, testing the compression strength after 28d standard curing, and drawing a linear relation graph of the compression strength and the glue ratio;
s3, taking the glue ratio with higher configuration strength as the glue ratio of the design mixing ratio;
s4, continuing to judge, and if the calculated volume weight difference of the concrete volume weight ratio of the trial mix proportion to the design mix proportion is more than 2%, correcting the following formula:
Figure BDA0002874910570000091
wherein: m isw、mc、mf、mgAnd msRespectively the water, cement, fly ash and/or mineral powder, the raw sand and the recycled aggregate (kg/m) of the recycled aggregate concrete with the final mixing ratio3)；pc,tTo try out the measured value of the apparent density of the concrete (kg/m)3)；pc,cCalculated value (kg/m) of concrete mixing ratio3)。
Example one
A design method of C30 recycled aggregate concrete for prefabricated buildings comprises the following steps:
step 1, determining the strength of recycled aggregate concrete, and calculating according to the following formula:
fcu.0≥fcu,k+1.645σ；
wherein: f. ofcu.0The value is the strength value of recycled aggregate concrete; f. ofcu,kThe standard value (MPa) of the cubic compressive strength of the recycled aggregate concrete; sigma isThe standard difference of the strength of the recycled aggregate concrete is 5.0;
i.e., fcu,kIs 30, therefore fcu.0＝30+1.645×5.0＝38.2MPa；
Step 2, determining the water-cement ratio of the recycled aggregate concrete, and calculating according to the following formula:
Figure BDA0002874910570000092
wherein:
Figure BDA0002874910570000093
the water-cement ratio of the recycled aggregate concrete is obtained; alpha is alphaaAnd alphabAre all regression coefficients, and αaValue of 0.53, alphabThe value is 0.20; f. ofbThe strength (MPa) of the gelled material 28d sand;
i.e. take fbThe pressure of the mixture is 37.4MPa,
Figure BDA0002874910570000101
step 3, determining the aggregate composition dosage of the recycled aggregate concrete: obtaining the total aggregate dosage of the recycled aggregate concrete according to a stacking density test of the minimum void fraction, namely the aggregate composition dosage of 1735kg used per cubic meter, and calculating the required raw sand dosage and the required recycled aggregate dosage according to the weight part ratio of the raw sand to the recycled aggregate, namely 9: 11;
and at this time, the amount of the primary sand is 1735kg/m3*0.45＝781kg/m3(ii) a The dosage of the recycled aggregate is 1735kg/m3-781kg/m3＝954kg/m3
Step 4, determining the water consumption of the recycled aggregate concrete, and calculating according to the following formula:
mw0＝mwo1(1-β)+mwo2；
wherein: m isw0The actual water consumption (kg/m) of each cubic of recycled aggregate concrete required by construction3)；mwo1Presumed to satisfy construction requirements without admixture of water-reducing agentWater consumption (kg/m) per cubic recycled aggregate concrete3) And m iswo1Based on the water consumption of 90mm slump, the slump is increased by 5kg/m for every 20mm3Calculating the water consumption; m iswo2The aggregate water absorption mass (kg/m) of each cubic recycled aggregate concrete3) (ii) a Beta is the water reducing rate (%) of the water reducing agent;
that is to say that the first and second electrodes,
Figure BDA0002874910570000102
mw0＝220×(1-26％)+1735×2.3％＝203kg/m3；
and 5, determining the dosage of the gel material, and calculating according to the following formula:
Figure BDA0002874910570000103
wherein: b ism0The total cementing material dosage (kg/m) of cement and admixture for recycled aggregate concrete3) (ii) a Calculating the required dosage of the cement, the fly ash and the mineral powder according to the weight part ratio of the cement, the fly ash and the mineral powder, namely 31:9: 10;
i.e. Bm0＝203/0.47＝432kg/m3(ii) a Cement consumption 432X 0.62 268kg/m3(ii) a The used amount of fly ash is 432 multiplied by 0.18 is 78kg/m3(ii) a The using amount of the mineral powder is 432 multiplied by 0.20 which is 82kg/m3；
Step 6, determining the dosage of the additive, and calculating according to 1.9% of the dosage of the cementing material;
namely, the dosage of the admixture is 432 to 1.9 percent and 8.21kg/m3；
And 7, adjusting the design mixing ratio, wherein the adjusting method of the design mixing ratio comprises the following steps:
s1, respectively increasing and decreasing by 0.05 according to the water-glue ratios obtained in the step 2 to form three water-glue ratios;
s2, continuing the steps 3 to 6 according to the three water-glue ratios obtained in the step S1, obtaining corresponding mixing ratios to adapt and mold a cubic compression-resistant test piece, testing the compression strength after 28d standard curing, and drawing a linear relation graph of the compression strength and the glue ratio;
s3, taking the glue ratio with higher configuration strength as the glue ratio of the design mixing ratio;
correspondingly, in the embodiment, the cement is P.O42.5, the fly ash is class F class II, and the mineral powder is class S95.
Wherein, the water-cement ratio of 0.47, 0.42 and 0.52 is respectively adopted to carry out a concrete mixing test, the slump and the apparent density of the mixing plant are respectively tested, and a 28d cube test piece is formed to carry out a group of test pieces of compressive strength, elastic modulus, impermeability, electric flux and carbonization test.
And compared by using the common concrete (designed according to JGJ 55-2011) of the comparative example I, namely C30, and the comparison result is shown in the following table I:
table-recycled aggregate concrete and common concrete test performance table
Figure BDA0002874910570000121
The slump of the trial concrete stirring material is 130-150mm, and the measured value and the calculated value of the apparent density are not more than 2%; as can be seen from the relationship between the concrete compressive strength and the glue ratio shown in FIG. 1, the compressive strength with the glue ratio of 2.03 is close to the design configuration strength, so that the mixing ratio is adjusted by selecting the glue ratio of 2.03, and the adjustment results are shown in Table II.
Material table for surface-II recycled aggregate concrete material
Figure BDA0002874910570000122
It is to be mentioned that the design grade of the C25-35 recycled aggregate concrete for the fabricated building is C30, and the slump is 100-160 mm; wherein the 28-day mortar compressive strength is 37.4 MPa; the fineness modulus of the primary sand is 2.9; the recycled aggregate has a particle size of 5-25mm, a minimum porosity of 43.0%, and a loose bulk density of 1735kg/m3The water absorption rate is 2.3%; and the water reducing rate of the admixture is 26 percent of polycarboxylic acid high-performance water reducing agent.
Example two
A design method of C25 recycled aggregate concrete for prefabricated buildings comprises the following steps:
step 1, determining the strength of recycled aggregate concrete, and calculating according to the following formula:
fcu.0≥fcu,k+1.645σ；
wherein: f. ofcu.0The value is the strength value of recycled aggregate concrete; f. ofcu,kThe standard value (MPa) of the cubic compressive strength of the recycled aggregate concrete; sigma is standard difference of strength of recycled aggregate concrete, and the value is 5.0;
i.e., fcu,kIs 25, therefore fcu.0＝25+1.645×5.0＝33.2MPa；
Step 2, determining the water-cement ratio of the recycled aggregate concrete, and calculating according to the following formula:
Figure BDA0002874910570000131
wherein:
Figure BDA0002874910570000132
the water-cement ratio of the recycled aggregate concrete is obtained; alpha is alphaaAnd alphabAre all regression coefficients, and αaValue of 0.53, alphabThe value is 0.20; f. ofbThe strength (MPa) of the gelled material 28d sand;
i.e. take fbThe pressure of the mixture is 37.4MPa,
Figure BDA0002874910570000133
step 3, determining the aggregate composition dosage of the recycled aggregate concrete: obtaining the total aggregate dosage of the recycled aggregate concrete according to a stacking density test of the minimum void fraction, namely the aggregate composition dosage of 1735kg used per cubic meter, and calculating the required raw sand dosage and the required recycled aggregate dosage according to the weight part ratio of the raw sand to the recycled aggregate, namely 9: 11;
and at this time,the consumption of the raw sand is 1735kg/m3*0.45＝781kg/m3(ii) a The dosage of the recycled aggregate is 1735kg/m3-781kg/m3＝954kg/m3
Step 4, determining the water consumption of the recycled aggregate concrete, and calculating according to the following formula:
mw0＝mwo1(1-β)+mwo2；
wherein: m isw0The actual water consumption (kg/m) of each cubic of recycled aggregate concrete required by construction3)；mwo1The estimated water consumption (kg/m) per cubic meter of recycled aggregate concrete which meets the construction requirements when the water reducing agent is not blended3) And m iswo1Based on the water consumption of 90mm slump, the slump is increased by 5kg/m for every 20mm3Calculating the water consumption; m iswo2The aggregate water absorption mass (kg/m) of each cubic recycled aggregate concrete3) (ii) a Beta is the water reducing rate (%) of the water reducing agent;
that is to say that the first and second electrodes,
Figure BDA0002874910570000141
mw0＝218×(1-26％)+1735×2.3％＝201kg/m3；
and 5, determining the dosage of the gel material, and calculating according to the following formula:
Figure BDA0002874910570000142
wherein: b ism0The total cementing material dosage (kg/m) of cement and admixture for recycled aggregate concrete3) (ii) a Calculating the required dosage of the cement, the fly ash and the mineral powder according to the weight part ratio of the cement, the fly ash and the mineral powder, namely 31:9: 10;
i.e. Bm0＝201/0.53＝379kg/m3(ii) a The cement consumption is 379X 0.62 235kg/m3(ii) a The use amount of the fly ash is 379 multiplied by 0.18 which is 68kg/m3(ii) a The using amount of the mineral powder is 379 multiplied by 0.20 to 76kg/m3；
Step 6, determining the dosage of the additive, and calculating according to 1.9% of the dosage of the cementing material;
namely, the dosage of the additive is 379 ═ 1.9 ═ 7.2kg/m3；
And 7, adjusting the design mixing ratio, wherein the adjusting method of the design mixing ratio comprises the following steps:
s1, respectively increasing and decreasing by 0.05 according to the water-glue ratios obtained in the step 2 to form three water-glue ratios;
s2, continuing the steps 3 to 6 according to the three water-glue ratios obtained in the step S1, obtaining corresponding mixing ratios to adapt and mold a cubic compression-resistant test piece, testing the compression strength after 28d standard curing, and drawing a linear relation graph of the compression strength and the glue ratio;
s3, taking the glue ratio with higher configuration strength as the glue ratio of the design mixing ratio;
correspondingly, in the embodiment, the cement is P.O42.5, the fly ash is class F class II, and the mineral powder is class S95.
Wherein, the water-cement ratio of 0.48, 0.53 and 0.58 are respectively adopted to carry out concrete mixing test, the slump and the apparent density of the mixing plant are respectively tested, and a 28d cube test piece is formed to carry out a group of test pieces of compressive strength, elastic modulus, impermeability, electric flux and carbonization test.
And compared with the conventional concrete (designed according to JGJ 55-2011) of the comparative example II, namely C25, and the comparison result is shown in the following table III:
test performance table for recycled aggregate concrete and common concrete
Figure BDA0002874910570000151
The slump of the trial concrete stirring material is 110-140mm, and the measured value and the calculated value of the apparent density are not more than 2%; as can be seen from the relationship between the concrete compressive strength and the glue ratio shown in FIG. 2, the compressive strength with the glue ratio of 1.89 is close to the design configuration strength, so the mix ratio is adjusted by selecting the glue ratio of 1.89, and the adjustment results are shown in Table IV.
Material table for recycled aggregate concrete material
Figure BDA0002874910570000161
It is to be mentioned that the design grade of the C25-35 recycled aggregate concrete for the fabricated building is C25, and the slump is 100-140 mm; wherein the 28-day mortar compressive strength is 37.4 MPa; the fineness modulus of the primary sand is 2.5; the recycled aggregate has a particle size of 5-25mm, a minimum porosity of 43.0%, and a loose bulk density of 1735kg/m3The water absorption rate is 2.3%; and the additive is a polycarboxylic acid high-performance water reducing agent with the addition water reducing rate of 26 percent.
EXAMPLE III
A design method of C35 recycled aggregate concrete for prefabricated buildings comprises the following steps:
step 1, determining the strength of recycled aggregate concrete, and calculating according to the following formula:
fcu.0≥fcu,k+1.645σ；
wherein: f. ofcu.0The value is the strength value of recycled aggregate concrete; f. ofcu,kThe standard value (MPa) of the cubic compressive strength of the recycled aggregate concrete; sigma is standard difference of strength of recycled aggregate concrete, and the value is 5.0;
i.e., fcu,kIs 35, therefore fcu.0＝35+1.645×5.0＝43.2MPa；
Step 2, determining the water-cement ratio of the recycled aggregate concrete, and calculating according to the following formula:
Figure BDA0002874910570000162
wherein:
Figure BDA0002874910570000171
the water-cement ratio of the recycled aggregate concrete is obtained; alpha is alphaaAnd alphabAre all regression coefficients, and αaValue of 0.53, alphabThe value is 0.20; f. ofbThe strength (MPa) of the gelled material 28d sand;
i.e. take fbThe pressure of the mixture is 47.5MPa,
Figure BDA0002874910570000172
step 3, determining the aggregate composition dosage of the recycled aggregate concrete: obtaining the total aggregate dosage of the recycled aggregate concrete according to a stacking density test of the minimum void fraction, namely the aggregate composition dosage of 1735kg used per cubic meter, and calculating the required raw sand dosage and the required recycled aggregate dosage according to the weight part ratio of the raw sand to the recycled aggregate, namely 9: 11;
and at this time, the amount of the primary sand is 1735kg/m3*0.45＝781kg/m3(ii) a The dosage of the recycled aggregate is 1735kg/m3-781kg/m3＝954kg/m3
Step 4, determining the water consumption of the recycled aggregate concrete, and calculating according to the following formula:
mw0＝mwo1(1-β)+mwo2；
wherein: m isw0The actual water consumption (kg/m) of each cubic of recycled aggregate concrete required by construction3)；mwo1The estimated water consumption (kg/m) per cubic meter of recycled aggregate concrete which meets the construction requirements when the water reducing agent is not blended3) And m iswo1Based on the water consumption of 90mm slump, the slump is increased by 5kg/m for every 20mm3Calculating the water consumption; m iswo2The aggregate water absorption mass (kg/m) of each cubic recycled aggregate concrete3) (ii) a Beta is the water reducing rate (%) of the water reducing agent;
that is to say that the first and second electrodes,
Figure BDA0002874910570000173
mw0＝215×(1-26％)+1735×2.3％＝199kg/m3；
and 5, determining the dosage of the gel material, and calculating according to the following formula:
Figure BDA0002874910570000181
wherein: b ism0The total cementing material dosage (kg/m) of cement and admixture for recycled aggregate concrete3) (ii) a Calculating the required dosage of the cement and the fly ash according to the weight part ratio of the cement, the fly ash and the mineral powder, namely 3: 1;
i.e. Bm0＝199/0.43＝463kg/m3(ii) a The cement consumption is 463 multiplied by 0.75 which is 347kg/m3(ii) a The use amount of the fly ash is 463 multiplied by 0.25 which is 116kg/m3；
Step 6, determining the dosage of the additive, and calculating according to 1.9% of the dosage of the cementing material;
namely, the additive dosage is 463 ═ 1.9 ═ 8.8kg/m3；
And 7, adjusting the design mixing ratio, wherein the adjusting method of the design mixing ratio comprises the following steps:
s1, respectively increasing and decreasing by 0.05 according to the water-glue ratios obtained in the step 2 to form three water-glue ratios;
s2, continuing the steps 3 to 6 according to the three water-glue ratios obtained in the step S1, obtaining corresponding mixing ratios to adapt and mold a cubic compression-resistant test piece, testing the compression strength after 28d standard curing, and drawing a linear relation graph of the compression strength and the glue ratio;
s3, taking the glue ratio with higher configuration strength as the glue ratio of the design mixing ratio;
correspondingly, in the embodiment, the cement is P.O42.5, the fly ash is class F class II, and the mineral powder is class S95.
Wherein, the water-cement ratio of 0.47, 0.42 and 0.52 is respectively adopted to carry out a concrete mixing test, the slump and the apparent density of the mixing plant are respectively tested, and a 28d cube test piece is formed to carry out a group of test pieces of compressive strength, elastic modulus, impermeability, electric flux and carbonization test.
And compared by adopting a third comparative example, namely C35 common concrete (designed according to JGJ 55-2011), the comparison result is shown as the following fifth table:
table five recycled aggregate concrete and common concrete test performance table
Figure BDA0002874910570000191
The slump of the trial concrete stirring material is 100-130mm, and the measured value and the calculated value of the apparent density are not more than 2%; and as can be seen from the relationship between the concrete compressive strength and the glue ratio shown in fig. 3, the compressive strength with the glue ratio of 2.19 is close to the design configuration strength, so the mixing ratio is adjusted by selecting the glue ratio of 2.19, and the adjustment result is shown in table six.
Material table for table six recycled aggregate concrete material
Figure BDA0002874910570000192
It is to be mentioned that the design grade of the C25-35 recycled aggregate concrete for the fabricated building is C35, and the slump is 90-130 mm; wherein the 28-day mortar compressive strength is 47.5 MPa; the fineness modulus of the primary sand is 2.9; the recycled aggregate has a particle size of 5-25mm, a minimum porosity of 43.0%, and a loose bulk density of 1735kg/m3The water absorption rate is 2.3%; and the additive is a polycarboxylic acid high-performance water reducing agent with the addition water reducing rate of 26 percent.
Example four
The difference between the fourth example and the third example is that the cement in the fourth example is p.o52.5.
EXAMPLE five
The difference between example five and example three is that the fly ash in example five is class F class I fly ash.
EXAMPLE six
The difference between the sixth embodiment and the third embodiment is that the ore powder in the sixth embodiment is of grade S105.
In summary, the C25-35 recycled aggregate concrete for the fabricated building and the design method thereof provided by the application obtain the required concrete of C25, C30 and C35 grades by the corresponding design method, and obtain the recycled aggregate concrete which has high mechanical and durable performances and can be used for fabricated members such as fabricated building enclosure walls, stacked floor slabs, stressed structure stacked secondary beams of multi-story buildings and the like while effectively utilizing and absorbing the recycled aggregate prepared by building disassembly garbage.
References in this application to "first," "second," "third," "fourth," etc., if any, are intended to distinguish between similar elements and not necessarily to describe a particular order or sequence. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Furthermore, the terms "comprises" and "comprising," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, or apparatus.
It should be noted that the descriptions in this application referring to "first", "second", etc. are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present application.
The principle and the implementation of the present application are explained herein by applying specific examples, and the above description of the embodiments is only used to help understand the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims (10)

1. The C25-35 recycled aggregate concrete for the fabricated building is characterized by comprising the following components in parts by weight:
432 portions of gel material 320-;
an aggregate composition 1735 parts;
3.2-10.4 parts of an additive;
wherein the gel material comprises 31-40:10-19 parts by weight of cement and mineral admixture, and the 28d compressive strength is not less than 27.4 MPa; the aggregate composition comprises primary sand and recycled aggregate according to the weight part ratio of 9: 11; the additive is a polycarboxylic acid high-performance water reducing agent.
2. The fabricated building C25-35 recycled aggregate concrete according to claim 1, wherein: the cement is P.O42.5-52.5; the mineral admixture is fly ash and mineral powder; and the fly ash is F class I-II; the mineral powder is in S95-105 grade.
3. The fabricated building C25-35 recycled aggregate concrete according to claim 1, wherein: the raw sand is natural sand and machine-made sand, and the fineness modulus is 2.5-2.9; the minimum porosity of the recycled aggregate is 43.0%, and the water absorption is 2.3-6.5%.
4. The fabricated building C25-35 recycled aggregate concrete according to claim 1, wherein: the minimum mixing amount water reducing rate of the polycarboxylic acid high-performance water reducing agent is 26%.
5. The fabricated building C25-35 recycled aggregate concrete according to claim 1, wherein: the slump of the recycled aggregate concrete is 50-160 mm.
6. A design method of C25-35 recycled aggregate concrete for prefabricated buildings is characterized by comprising the following steps:
step 1, determining the strength of recycled aggregate concrete, and calculating according to the following formula:
fcu.0≥fcu,k+1.645σ；
wherein: f. ofcu.0The value is the strength value of recycled aggregate concrete; f. ofcu,kThe standard value (MPa) of the cubic compressive strength of the recycled aggregate concrete; sigma is standard difference of strength of recycled aggregate concrete, and the value is 5.0;
step 2, determining the water-cement ratio of the recycled aggregate concrete, and calculating according to the following formula:
Figure FDA0002874910560000021
wherein:
Figure FDA0002874910560000022
the water-cement ratio of the recycled aggregate concrete is obtained; alpha is alphaaAnd alphabAre all regression coefficients, and αaValue of 0.53, alphabThe value is 0.20; f. ofbThe strength (MPa) of the gelled material 28d sand;
step 3, determining the aggregate composition dosage of the recycled aggregate concrete: obtaining the aggregate total dosage of the recycled aggregate concrete according to a stacking density test of the minimum void fraction, namely the dosage of the aggregate composition of 1735kg used per cubic meter, and calculating the required dosage of the raw sand and the recycled aggregate according to the weight part ratio of the raw sand to the recycled aggregate;
step 4, determining the water consumption of the recycled aggregate concrete, and calculating according to the following formula:
mw0＝mwo1(1-β)+mwo2；
wherein: m isw0The actual water consumption (kg/m) of each cubic of recycled aggregate concrete required by construction3)；mwo1The estimated water consumption (kg/m) per cubic meter of recycled aggregate concrete which meets the construction requirements when the water reducing agent is not blended3)；mwo2The aggregate water absorption mass (kg/m) of each cubic recycled aggregate concrete3) (ii) a Beta is the water reducing rate (%) of the water reducing agent;
and 5, determining the dosage of the gel material, and calculating according to the following formula:
Figure FDA0002874910560000023
wherein: b ism0The total cementing material dosage (kg/m) of cement and admixture for recycled aggregate concrete3) (ii) a Calculating the required dosage of the cement and the mineral admixture according to the weight part ratio of the cement to the mineral admixture;
and 6, determining the dosage of the additive, and calculating according to 1.9% of the dosage of the cementing material.
7. The method for designing C25-35 recycled aggregate concrete for prefabricated buildings according to claim 6, wherein the adjustment of the design mix ratio is continued after the gel material usage amount is determined through the step 5; the method for adjusting the design mixing ratio comprises the following steps:
s1, respectively increasing and decreasing by 0.05 according to the water-glue ratios obtained in the step 2 to form three water-glue ratios;
s2, continuing the steps 3 to 5 according to the three water-glue ratios obtained in the step S1, obtaining corresponding mixing ratios to adapt and mold a cubic compression-resistant test piece, testing the compression strength after 28d standard curing, and drawing a linear relation graph of the compression strength and the glue ratio;
s3, taking the glue ratio with higher configuration strength as the glue ratio of the design mixing ratio;
s4, continuing to judge, and if the calculated volume weight difference of the concrete volume weight ratio of the trial mix proportion to the design mix proportion is more than 2%, correcting the following formula:
Figure FDA0002874910560000031
wherein: m isw、mc、mf、mgAnd msWater, cement and powder of recycled aggregate concrete with final mixing ratio respectivelyCoal ash and/or mineral powder, raw sand and recycled aggregate (kg/m)3)；pc，tTo try out the measured value of the apparent density of the concrete (kg/m)3)；pc,cCalculated value (kg/m) of concrete mixing ratio3)。
8. The design method of the C25-35 recycled aggregate concrete for the fabricated building according to claim 6, wherein the design method comprises the following steps: in the step 3, the weight part ratio of the raw sand to the recycled aggregate is 9: 11.
9. The design method of the C25-35 recycled aggregate concrete for the fabricated building according to claim 6, wherein the design method comprises the following steps: in step 4, mwo1Based on the water consumption of 90mm slump, the slump is increased by 5kg/m for every 20mm3And calculating the water consumption.
10. The design method of the C25-35 recycled aggregate concrete for the fabricated building according to claim 6, wherein the design method comprises the following steps: in step 5, the weight ratio of the cement to the mineral admixture is 31-40: 10-19.
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