CN111620619A - C70 self-compacting shrinkage-compensating concrete filled steel tube and preparation method thereof - Google Patents
C70 self-compacting shrinkage-compensating concrete filled steel tube and preparation method thereof Download PDFInfo
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- CN111620619A CN111620619A CN202010373308.6A CN202010373308A CN111620619A CN 111620619 A CN111620619 A CN 111620619A CN 202010373308 A CN202010373308 A CN 202010373308A CN 111620619 A CN111620619 A CN 111620619A
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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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00146—Sprayable or pumpable mixtures
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/34—Non-shrinking or non-cracking materials
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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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Abstract
The invention discloses C70 self-compacting shrinkage-compensating concrete filled steel tubes and a preparation method thereof, wherein each cubic concrete consists of the following raw materials by mass: 450kg to 470kg of cement, 45kg to 70kg of fly ash or micro-beads, 40kg to 55kg of silicon powder, 50kg to 55kg of composite expanding agent, 952kg to 1008kg of coarse aggregate, 730kg to 754kg of fine aggregate, 8.85kg to 9.75kg of high-performance water reducing agent and 163kg to 171kg of water. According to the invention, the types of mineral admixtures, fine aggregates and coarse aggregates are reasonably selected, the theory of a ball effect is fully utilized, and the viscosity is scientifically reduced by a physical viscosity reduction method, so that the large flow property of concrete is effectively ensured; by optimizing the formula of the water reducing agent and the expanding agent, the air content of the concrete is reduced, the free expansion rate of the concrete is increased to compensate shrinkage, the concrete is prevented from being debonded from the inner wall of the steel pipe, and the volume stability of the concrete is effectively guaranteed. Therefore, the technical problem that the working performance of the high-strength self-compaction compensation shrinkage concrete filled steel tube is matched with the construction process of a pumping jacking method is solved.
Description
Technical Field
The invention relates to the technical field of concrete, in particular to C70 self-compacting shrinkage-compensating concrete filled steel tubes and a preparation method thereof.
Background
The steel pipe concrete is a structural member which is formed by filling concrete in a steel pipe, and the steel pipe and core concrete of the steel pipe can bear the external load together, and has the advantages of high bearing capacity, good plasticity and toughness, remarkable economic benefit and the like; with the rapid development of national economy and the continuous updating of construction technology, the advantages of the steel pipe concrete structure are more fully exerted, so that the steel pipe concrete structure is widely applied to various large-scale building engineering and transportation engineering, in particular to the application in large-span (arch bridge, cable-stayed bridge and the like) bridge engineering.
The working performance of the concrete-filled steel tube is the guarantee of the construction quality of the concrete-filled steel tube structure, and for a large-span concrete-filled steel tube arch bridge in traffic transportation engineering, the construction problems of fast concrete collapse loss, poor fluidity, large pumping pressure, pipe blockage and the like easily occur in the construction, and the phenomenon that the concrete in the pipe is not compact and is debonded from the steel pipe easily occurs, so that the quality defect is formed. The construction performance (high fluidity and low cohesiveness) and the mechanical performance (high strength and volume stability) of the concrete are the technical difficulties of concrete design and quality control.
Along with the continuous improvement of the national requirements for the quality of engineering construction, the quality requirements for sandstone materials are higher and higher, and because the natural river sand is forbidden to be mined by environmental protection and the original natural river sand resources in partial areas are deficient, the natural river sand capable of meeting the requirements are less and less, and the application of the machine-made sand in the high-strength self-compaction compensation shrinkage steel pipe concrete is better popularized.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides C70 self-compacting shrinkage-compensating concrete filled steel tube and a preparation method thereof, and the concrete filled steel tube has the performances of high strength, high fluidity, low cohesiveness, self-compacting property, shrinkage compensation, good slump retaining effect and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
a C70 self-compacting shrinkage-compensating steel tube concrete, wherein the dosage of each cubic meter of concrete is as follows: 450kg to 470kg of cement, 45kg to 70kg of micro-beads, 40kg to 55kg of silicon powder, 50kg to 55kg of composite expanding agent, 952kg to 1008kg of coarse aggregate, 730kg to 754kg of fine aggregate, 8.85kg to 9.75kg of high-performance water reducing agent and 163kg to 171kg of water.
Preferably, the micro-beads are spherical amorphous fly ash micro-beads, the thixotropic index of the micro-beads is 7.5, and the sphere density and the bulk density are 2520kg/m respectively3、650kg/m3The specific surface area is 1300m2The activity index is 87 percent, the ignition loss is 1.21 percent, and the water demand ratio is 98 percent.
Preferably, the silicon powder has a specification of SF90 or more and a specific surface area of no less than 15000m2Kg, activity index not less than 90%.
Further, the composite expanding agent is prepared from calcium oxide and magnesium oxide according to the following formula (2-4): (6-8) in mass ratio.
Further, the coarse aggregate is crushed stone with 5-16mm continuous gradation and the crushing value is less than 18%.
Further, the coarse aggregate is prepared by mixing 5-10 mm and 10-16 mm of crushed stones according to the proportion of (1-5): (9-5) in a ratio.
Preferably, the crushed stone is crushed stone of basalt and limestone with the saturated uniaxial compressive strength of not less than 105MPa of gravel or mother rock crushed by cobblestones; when the coarse aggregate is prepared, one kind of the macadam can be adopted independently, and at least two kinds of mixed macadams which can be combined randomly can also be adopted.
Preferably, the fine aggregate is machine-made sand or natural river sand which is crushed by basalt and cobblestones, the specification of the fine aggregate is 0 mm-4.75 mm, and the fineness modulus is 2.8-3.0.
Further, the high-performance water reducing agent comprises the following components in percentage by mass: 38-45% of water-reducing mother liquor, 11-22% of slump retaining agent, 10-17% of composite water-reducing slump retaining mother liquor, 0.08-0.2% of defoaming agent, 0.05-0.15% of composite defoaming air-entraining agent, 2-5% of white sugar, 2-4% of sodium gluconate, 1-3% of water-retaining agent and the balance of water.
Preferably, the water-reducing mother liquor is a composition of isobutylene alcohol polyoxyethylene ether and hydroxyethyl acrylate;
the slump retaining agent is one or a mixture of more than two of citric acid or sodium gluconate, sodium tripolyphosphate or sodium hexametaphosphate;
the composite water-reducing slump-retaining mother liquor is a copolymer of hydroxyethyl acrylate and methyl allyl polyoxyethylene ether; the defoaming agent is one or a mixture of more than two of C7-C22 high-carbon alcohol, polyether defoaming agent and organosilicon defoaming agent in any proportion;
the composite defoaming air entraining agent is one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, fatty alcohol-polyoxyethylene ether, sodium fatty alcohol-polyoxyethylene sulfonate and sodium fatty alcohol sulfate.
The water retaining agent is white powdery hydroxypropyl methyl cellulose ether.
The preparation method of the C70 self-compacting shrinkage-compensating concrete filled steel tube comprises the following steps: the method comprises the steps of firstly, respectively adding cement, silicon powder, a composite expanding agent, coarse aggregates, fine aggregates and fly ash or microbeads in a formula ratio into a mixer pot body for stirring, stirring for 20-40 seconds to fully and uniformly mix the aggregates and powder, then mixing water in a formula ratio with a high-performance water reducing agent to form a mixed solution, adding the mixed solution into the mixer pot body, and continuously stirring for 140-160 seconds to obtain the C70 self-compacting compensation shrinkage steel pipe concrete.
By adopting the technical scheme, the invention has the following beneficial effects:
1. according to the invention, the types of mineral admixtures, fine aggregates and coarse aggregates are reasonably selected, and the rolling ball effect theory is fully utilized to scientifically reduce viscosity through a physical viscosity reduction method, so that the large flow property of concrete is effectively ensured.
2. The calcium oxide and magnesium oxide compound type expanding agent adopted by the invention has low water requirement for expansion reaction, is more suitable for the environmental conditions of the steel pipe concrete with low water-cement ratio, and the calcium oxide and the magnesium oxide respectively have expansion reaction in the early stage and the middle and later stages of the concrete, and are reasonably matched, so that the period of an expansion peak value is shortened, the self-shrinkage of the steel pipe concrete is effectively compensated, the early strength is improved, and the volume stability of the steel pipe concrete is ensured.
3. The invention utilizes the spherical structure of the fly ash micro-beads to reduce the viscosity of concrete (cement paste), improve the workability of the concrete, reduce the pressure injection resistance of the concrete and improve the pumping performance of the concrete, and utilizes the spherical structure to reduce the viscosity of the concrete (cement paste), improve the workability of the concrete, reduce the pressure injection resistance of the concrete and improve the pumping performance of the concrete
4. The invention solves the bleeding of the concrete under high fluidity by doping the silicon powder, improves the workability of the concrete, and increases the compactness of the concrete, thereby improving the strength and the pumping performance of the concrete.
5. The aggregates (coarse aggregates and fine aggregates) selected by the invention are subjected to shaping treatment, the grain type edges and corners are round and regular, and the adopted grain size is 5-16mm, so that the aggregates are easy to suspend in concrete slurry, the uniformity of the concrete is ensured, and the fluidity and the self-compactness of the concrete are facilitated.
6. The C70 self-compacting shrinkage-compensating concrete filled steel tube has the characteristic of high strength, and mainly reflects that the compressive strength is greater than 80% of the designed strength in 3 days and is greater than 115% of the designed strength in 28 days; the high strength not only ensures the structural quality, but also shortens the intermittent period of the working procedure by the high strength of 3 days, thereby shortening the construction period, improving the construction efficiency, saving the cost and generating considerable economic benefit.
7. The C70 self-compaction shrinkage-compensating steel tube concrete has the characteristics of low viscosity and high fluidity, and is mainly characterized in that the concrete mixture has good wrapping property, no segregation and no bleeding in the fluid stateLess tacky; the slump is 250-270mm, the slump expansion is 670-700mm, and T500The pumping pressure and the construction risk are reduced due to the good workability of the concrete for 8-10s, and the equipment investment is reduced, so that the construction quality is ensured, and the construction cost is saved.
8. The C70 self-compacting shrinkage-compensating concrete filled steel tube has the characteristic of shrinkage compensation, and the free expansion rate is greater than 0 in a 28d closed environment; by scientifically selecting an expansion source and reasonably combining the expansion source, the period of an expansion peak value is shortened, the self-contraction of the concrete-filled steel tube is effectively compensated, the technical problem of debonding of the concrete and the inner wall of the steel tube is solved, and the volume stability of the concrete-filled steel tube is ensured.
The foregoing is a summary of the present invention, and in order to provide a clear understanding of the technical means of the present invention and to be implemented in accordance with the present specification, preferred embodiments of the present invention are described in detail below.
Detailed Description
The embodiments of the present invention are described below in terms of specific embodiments, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein.
Example 1
The embodiment provides a C70 self-compacting shrinkage-compensating concrete filled steel tube, and specifically, the dosage of each material per cubic meter of concrete is as follows: 450kg to 470kg of cement, 45kg to 70kg of micro-beads, 40kg to 55kg of silicon powder, 50kg to 55kg of composite expanding agent, 952kg to 1008kg of coarse aggregate, 730kg to 754kg of fine aggregate, 8.85kg to 9.75kg of high-performance water reducing agent and 163kg to 171kg of water.
The invention also provides a preparation method of the C70 self-compaction shrinkage-compensated concrete filled steel tube, which comprises the following steps: and (2) mixing by adopting a forced mixer, respectively putting aggregates (coarse aggregates and fine aggregates) and powder (cement, fly ash or microbeads, silicon powder and a composite expanding agent) into a mixer pot body for stirring, stirring for 20-40 seconds to fully and uniformly mix the aggregates and the powder, mixing water with a high-performance water reducing agent in a formula ratio to obtain a mixed solution, adding the mixed solution obtained after mixing the water with the high-performance water reducing agent into the mixer pot body, and continuously stirring for 140-160 seconds to obtain the C70 self-compacting compensation shrinkage steel tube concrete. It should be noted that the stirring is not interrupted in the whole process, so as to ensure the uniform mixing of the concrete, and the total stirring time is not less than 180 seconds.
In order to reduce the viscosity of concrete and improve the pumping performance of concrete, the prior art mostly adopts a chemical viscosity reduction method (adding a chemical viscosity reducer) to adjust the workability of concrete, but the concrete workability fluctuates greatly due to the change of concrete materials and the fluctuation of admixture mixing amount, so that the concrete has poor fluidity, segregation, bleeding and layering, so that accidents such as pipe blockage, pipe explosion, non-compact concrete in a steel pipe and the like occur, and the construction efficiency and the quality are directly influenced. The invention reasonably selects the types of mineral admixtures, fine aggregates and coarse aggregates, fully utilizes the theory of the ball effect, and scientifically reduces viscosity by a physical viscosity reduction method, thereby effectively ensuring the large flow property of concrete; by optimizing the formula of the water reducing agent and the expanding agent, the air content of the concrete is reduced, the free expansion rate of the concrete is increased to compensate shrinkage, the concrete is prevented from being debonded from the inner wall of the steel pipe, and the volume stability of the concrete is effectively guaranteed.
Example 2
On the basis of the above embodiment, further, the fly ash is F-type I-grade low-calcium fly ash, wherein the mass content of free CaO<1 percent and the fineness of the class I F fly ash is not more than 12 percent. The micro-beads are spherical amorphous fly ash micro-beads, the specification is MB-TC01B, the thixotropic index is 7.5, and the sphere density and the bulk density are 2520kg/m respectively3、650kg/m3The specific surface area is 1300m2Per kg, the activity index is 87 percent, the loss on ignition is 1.21 percent, and the water demand ratio is 98 percent; the invention mixes the spherical amorphous fly ash micro-beads, utilizes the spherical structure of the fly ash micro-beads and fully utilizes the theory of the ball effect, reduces the viscosity of concrete (cement paste) by a physical mode (the ball effect), improves the workability of the concrete, reduces the pressure injection resistance of the concrete and improves the pumping performance of the concrete.
Further, the specification of the silicon powder is SF90 or more, and the specific surface area is not less than 15000m2Kg, activity ofThe sex index is not less than 90%. The silicon powder is added mainly to avoid bleeding of the concrete under high fluidity, improve the workability of the concrete and increase the compactness of the concrete, thereby improving the strength and the pumping performance of the concrete.
Example 3
In order to prevent the concrete from shrinking and avoid the concrete from being debonded from the steel pipe, in the application of the prior art, an inorganic compound type expanding agent such as aluminum sulfate, aluminum oxide, calcium sulfate and the like is often added to achieve the purposes of limiting shrinkage and micro-expansion; however, the composite expanding agent needs more water for hydration, and because of the low water-cement ratio of the concrete with the steel pipe and the closed special environment which is not in contact with the outside, the water needed for the hydration of the expanding agent cannot be effectively provided, so that the effect of the expanding agent is influenced, the effects of shrinkage compensation and micro-expansion cannot be fully exerted, the concrete and the steel pipe are debonded, the internal compactness of the concrete cannot be effectively improved, the strength of the concrete is reduced, and the structural stress is influenced.
The composite expanding agent is prepared from calcium oxide and magnesium oxide in a weight ratio of (2-4): (6-8), the calcium oxide and magnesium oxide expanding agents have lower water requirement for expansion reaction than expanding agents of other expansion sources, are more suitable for the environmental conditions of the steel pipe concrete with low water-cement ratio, and respectively have expansion reaction in the early stage and the middle and later stages of the concrete, so that the expansion peak period is reasonably matched, the self-shrinkage of the steel pipe concrete is effectively compensated, the early strength is improved, and the volume stability of the steel pipe concrete is ensured.
Example 4
On the basis of the above examples, further, the coarse aggregate is crushed stone 5-16mm continuous gradation, and the crushing value is less than 18%. Preferably, the coarse aggregate is prepared by mixing crushed stones with the weight ratio of 5-10 mm and 10-16 mm according to the ratio of (1-5): (9-5) mixing; the crushed stone is preferably crushed stone formed by crushing basalt and limestone with the saturated uniaxial compressive strength of not less than 105MPa of gravel or mother rock crushed by cobblestones; when the coarse aggregate is prepared, one kind of crushed stone can be adopted independently, or at least two kinds of mixed crushed stones which can be randomly combined can be adopted, and the combination type and the proportion of the crushed stones are not limited.
Further, the specification of the fine aggregate is 0 mm-4.75 mm; the fine aggregate is machine-made sand obtained by crushing basalt and cobblestone or natural river sand (lake sand), and has fineness modulus of 2.8-3.0.
The invention selects the crushed stone with the specification of 5-16mm and the secondary-zone graded sand with the fineness modulus within the range of 2.7-3.0, scientifically selects the proportion and effectively ensures the strength index.
It is worth mentioning that the selected aggregates are subjected to shaping treatment, the grain type edges and corners are smooth and regular, and the aggregates are 5-16mm in grain size and are easy to suspend in concrete slurry, so that the uniformity of the concrete is ensured, and the fluidity and the self-compactness of the concrete are facilitated.
The preferred technical requirements of each raw material in the C70 self-compacting shrinkage-compensated concrete filled steel tube are as follows in the following table 1:
table 1 shows the raw material specifications
It needs to be further explained that the invention can reasonably select the types of mineral admixtures, fine aggregates and coarse aggregates according to the actual conditions of the market and according to local conditions, the micro-beads and the fly ash can be replaced mutually, the cobblestone crushed stones and the basalt crushed stones can be replaced mutually, and the river sand and the machine-made sand can be replaced mutually.
Example 5
Different from the embodiment, the high-performance water reducing agent comprises the following components in percentage by mass: 38-45% of water-reducing mother liquor, 11-22% of slump retaining agent, 10-17% of composite water-reducing slump retaining mother liquor, 0.08-0.2% of defoaming agent, 0.05-0.15% of composite defoaming air-entraining agent, 2-5% of white sugar, 2-4% of sodium gluconate, 1-3% of water-retaining agent and the balance of water.
Preferably, the water-reducing mother liquor is a composition of isobutylene alcohol polyoxyethylene ether and hydroxyethyl acrylate;
the slump retaining agent is one or a mixture of more than two of citric acid or sodium gluconate, sodium tripolyphosphate or sodium hexametaphosphate;
the composite water-reducing slump-retaining mother liquor is a copolymer of hydroxyethyl acrylate and methyl allyl polyoxyethylene ether; the defoaming agent is one or a mixture of more than two of C7-C22 high-carbon alcohol, polyether defoaming agent and organosilicon defoaming agent in any proportion;
the composite defoaming air entraining agent is one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, fatty alcohol-polyoxyethylene ether, sodium fatty alcohol-polyoxyethylene sulfonate and sodium fatty alcohol sulfate.
The water retaining agent is white powdery hydroxypropyl methyl cellulose ether.
The invention aims to effectively improve the workability of concrete mixtures and control the working performances of concrete slump, slump expansion, air content, setting time, slump (expansion) loss and the like over time by doping a high-performance water reducing agent.
Example 6
The embodiment provides C70 self-compacting shrinkage-compensating concrete filled steel tube, wherein the dosage of each material in each cubic meter of concrete is as follows: microbeads: silicon powder: a composite expanding agent: coarse aggregate (crushed stone): fine aggregate (machine-made sand): high-performance water reducing agent: 460% of water: 57.5: 47.5: 52.5: 980: 742: 9.3: 167.
further, the coarse aggregate is formed by crushing cobblestones and is subjected to shaping treatment, 5mm-16mm continuous gradation (the proportion of crushed stones with the specification of 5mm-10mm and 10mm-16mm is 2: 8), the needle sheet content is 0%, the crushing value is 13.9%, the mud content is 0.4%, and the apparent density is 2951kg/m3The compression strength of the parent rock is 168 MPa.
The fine aggregate is machine-made sand formed by crushing basalt, the fineness modulus is 2.98, the stone powder content is 7.9%, the crushing value is 12%, and the apparent density is 2926kg/m3。
The high-performance water reducing agent is a retarding polycarboxylic acid high-performance water reducing agent.
The preparation method of the C70 self-compacting shrinkage-compensated concrete filled steel tube described in this example is as follows: firstly, respectively adding cement, silicon powder, a composite expanding agent, coarse aggregate, fine aggregate and fly ash or microbeads in a formula ratio into a mixer pot body for stirring, stirring for 30 seconds to fully and uniformly mix the aggregate and the powder, then mixing water and a high-performance water reducing agent in a formula ratio into a mixed solution, and then adding the mixed solution into the mixer pot body for continuously stirring for 150 seconds to obtain the C70 self-compacting compensation shrinkage steel pipe concrete.
The raw material used in the embodiment is preferably grade P.O 42.5 cement produced by Chongqing Huaxingdivi cement Co; tianjin is built into the microbeads with the specification of MB-TC01B produced by New Material science and technology Limited; SF90 silicon powder of the specification produced by Woodson engineering materials, Inc.; FQY high-performance expanding agent produced by Wuhan three-source special building materials Limited liability company; a retarding polycarboxylic acid high-performance water reducing agent produced by Shanghai Sanrui high polymer materials GmbH.
Example 7
The embodiment provides C70 self-compacting shrinkage-compensating concrete filled steel tube, wherein the dosage of each material in each cubic meter of concrete is as follows: microbeads: silicon powder: a composite expanding agent: coarse aggregate (crushed stone): fine aggregate (machine-made sand): high-performance water reducing agent: 470 parts of water: 70: 55: 55: 952: 734: 9.75: 163.
further, the coarse aggregate is formed by crushing basalt and is subjected to shaping treatment, 5mm-16mm continuous gradation (the proportion of crushed stones with the specification of 5mm-10mm and 10mm-16mm is 3:7), the needle sheet content is 0%, the crushing value is 13.9%, the mud content is 0.4%, and the apparent density is 2951kg/m3The compression strength of the parent rock is 168 MPa.
The fine aggregate is machine-made sand formed by crushing basalt, the fineness modulus is 2.98, the stone powder content is 7.9%, the crushing value is 12%, and the apparent density is 2926kg/m3。
The high-performance water reducing agent adopts a retarding polycarboxylic acid high-performance water reducing agent, and comprises the following effective components: 45% of water-reducing mother liquor, 13% of slump retaining agent, 17% of composite water-reducing slump retaining mother liquor, 0.08% of defoaming agent, 0.1% of composite defoaming air-entraining agent, 2% of white sugar, 3% of sodium gluconate, 1% of water-retaining agent and 18.82% of water.
The preparation method of the C70 self-compacting shrinkage-compensated concrete filled steel tube described in this example is as follows: firstly, the cement, the silicon powder, the composite expanding agent, the coarse aggregate, the fine aggregate and the fly ash with the formula ratio are mixedOr respectively putting the microbeads into a mixer pot to be mixed, mixing for 30 seconds to fully mix the aggregates and the powder, mixing the water with the formula amount and the high-performance water reducing agent into a mixed solution, adding the mixed solution into the mixer pot, and continuously mixing for 150 seconds to obtain the C70 self-compacting shrinkage-compensated steel tube concrete. The prepared concrete mixture has very good wrapping property and fluidity, the state of the concrete mixture is very good after 3 hours, obvious amplification and reduction phenomena do not exist, various performance indexes of the concrete mixture are detected according to a test method specified by a relevant standard, and the results are as follows: slump of 245mm, slump spread of 690mm, T50010s, 2.0 percent of gas content, 86.5MPa of 28d compressive strength and 4.02 × 10 of 28d elastic modulus4Free expansion rate of 2.3 × 10 under MPa and 28d closed environment-4And various performance indexes of the concrete meet the requirements of construction process and structural design quality.
Example 8
The embodiment provides C70 self-compacting shrinkage-compensating concrete filled steel tube, wherein the dosage of each material in each cubic meter of concrete is as follows: microbeads: silicon powder: a composite expanding agent: coarse aggregate (crushed stone): fine aggregate (sand): high-performance water reducing agent: 460% of water: 70: 45: 55: 952: 754: 9.45: 164.
the coarse aggregate is formed by crushing basalt, is subjected to shaping treatment, and is 5mm-16mm continuous gradation (the proportion of crushed stones with the specification of 5mm-10mm and 10mm-16mm is 3:7), the needle sheet content is 0%, the crushing value is 13.9%, the mud content is 0.4%, and the apparent density is 2951kg/m3The compression strength of the parent rock is 168 MPa.
The fine aggregate is machine-made sand formed by crushing cobblestones, the fineness modulus is 2.87, the stone powder content is 3.5%, the crushing value is 13%, and the apparent density is 2720kg/m3。
The high-performance water reducing agent adopts a retarding polycarboxylic acid high-performance water reducing agent, and comprises the following effective components: 40% of water-reducing mother liquor, 22% of slump retaining agent, 5% of composite water-reducing slump retaining mother liquor, 0.08% of defoaming agent, 0.05% of composite defoaming air-entraining agent, 2.5% of white sugar, 2% of water-retaining agent, 1% of sodium gluconate and 27.37% of water.
The C70 self-compacting patch described in this exampleThe preparation method of the shrinkage-compensating steel pipe concrete comprises the following steps: firstly, respectively adding cement, silicon powder, a composite expanding agent, coarse aggregate, fine aggregate and fly ash or microbeads in a formula ratio into a mixer pot body for stirring, stirring for 30 seconds to fully and uniformly mix the aggregate and the powder, then mixing water and a high-performance water reducing agent in a formula ratio into a mixed solution, and then adding the mixed solution into the mixer pot body for continuously stirring for 150 seconds to obtain the C70 self-compacting compensation shrinkage steel pipe concrete. The prepared concrete mixture has very good wrapping property and fluidity, the state of the concrete mixture is very good after 3 hours, obvious amplification and reduction phenomena do not exist, various performance indexes of the concrete mixture are detected according to a test method specified by a relevant standard, and the results are as follows: slump of 255mm, slump spread of 700mm, T5009s, 2.0 percent of gas content, 84.5MPa of 28d compressive strength, 4.12 × 104MPa of 28d elastic modulus and 2.1 × 10-4 of free expansion rate under 28d closed environment, and each performance index of the concrete meets the requirements of construction process and structural design quality.
Example 9
The embodiment provides C70 self-compacting shrinkage-compensating concrete filled steel tube, wherein the dosage of each material in each cubic meter of concrete is as follows: fly ash: silicon powder: a composite expanding agent: coarse aggregate (crushed stone): fine aggregate (sand): high-performance water reducing agent: water 450: 45: 40: 55: 1008: 730: 8.85: 171.
the coarse aggregate is formed by crushing cobblestones, and is subjected to shaping treatment, 5mm-16mm continuous gradation (the proportion of crushed stones with the specification of 5mm-10mm and 10mm-16mm is 4:6), 0% of needle slice content, 9.7% of crushing value, 0.4% of mud content and 2710kg/m apparent density3。
The fine aggregate is natural river sand, the fineness modulus is 2.87, the mud content is 0.7 percent, and the apparent density is 2720kg/m3。
The high-performance water reducing agent adopts a retarding polycarboxylic acid high-performance water reducing agent, and comprises the following effective components: 28% of water-reducing mother liquor, 11% of slump retaining agent, 10% of composite water-reducing slump retaining mother liquor, 0.5% of defoaming agent, 0.1% of composite defoaming air-entraining agent, 3% of white sugar, 2% of sodium gluconate, 3% of water-retaining agent and 42.4% of water.
The preparation method of the C70 self-compacting shrinkage-compensated concrete filled steel tube described in this example is as follows: firstly, respectively adding cement, silicon powder, a composite expanding agent, coarse aggregate, fine aggregate and fly ash or microbeads in a formula ratio into a mixer pot body for stirring, stirring for 30 seconds to fully and uniformly mix the aggregate and the powder, then mixing water and a high-performance water reducing agent in a formula ratio into a mixed solution, and then adding the mixed solution into the mixer pot body for continuously stirring for 150 seconds to obtain the C70 self-compacting compensation shrinkage steel pipe concrete. The prepared concrete mixture has very good wrapping property and fluidity, the state of the concrete mixture is very good after 3 hours, obvious amplification and reduction phenomena do not exist, various performance indexes of the concrete mixture are detected according to a test method specified by a relevant standard, and the results are as follows: slump of 260mm, slump spread of 700mm, T5008s, 1.8 percent of gas content, 82.6MPa of 28d compressive strength and 4.09 × 10 of 28d elastic modulus4Free expansion rate of 1.9 × 10 under MPa and 28d closed environment-4And various performance indexes of the concrete meet the requirements of construction process and structural design quality.
The mechanical properties of the concrete described in examples 7 to 9 were evaluated by measuring the 3-day and 28-day compressive strength of the standard concrete specimen under standard conditions and by ultrasonic testing of the field structure; the construction performance of the concrete comprises concrete mixture slump, slump expansion, 3 h-time slump expansion and T500Detecting and evaluating the relevant parameters; the concrete volume stability is evaluated by detecting the gas content of a concrete mixture in the construction process, detecting the free expansion rate of a concrete test piece 28d in a closed environment and detecting the field structure by ultrasonic waves, and specific performance indexes are shown in the following table 2.
Table 2 shows the concrete workability control indexes
The test methods are all test methods specified by national and industrial standards, have no special points and are not specially described.
The application comprises the following steps: hair brushThe C70 self-compaction compensation shrinkage steel pipe concrete is arranged in a first bridge world of the same type in an engineering entity (the total length of a highway bridge in Hejiang Yangtze river, the length of a main bridge is 1420m, the length of an approach bridge (including a platform back butt strap) is 752m, the span (507m) of a flying swallow type steel pipe concrete tied arch bridge of the main bridge is arranged in a way that 20 × 30m (simply supported T-shaped beam) + (80.5+507+80.5) m (flying swallow type steel pipe concrete tied arch) +4 × 25m (simply supported T-shaped beam), a main arch ring and a main chord pipe of an edge arch ring are respectively provided with 8 simple supported T-shaped beams
Steel pipe composition, the concrete in the main chord pipe adopts C70 self-compaction compensation shrinkage steel pipe concrete), and the construction superior performances of low viscosity, high fluidity, small slump loss under high temperature environment, small pumping pressure and the like of the concrete are fully verified; after construction, through knocking and ultrasonic detection, the concrete in the pipe is uniform and dense, and no void occurs, so that the reliability of mechanical properties of the concrete, such as high strength, volume stability and the like, is further demonstrated. Therefore, the concrete filled steel tube is a combined structure, and has volume stability (namely shrinkage compensation performance) and strength matching performance (namely high strength characteristic) in the aspect of structural stress, so that the technical problem that the working performance of the high-strength self-compaction shrinkage compensation concrete filled steel tube is matched with a pumping jacking method construction process (the process requires that concrete must have the characteristics of low viscosity and high fluidity, and is mainly reflected in the characteristics that a concrete mixture has good wrapping performance, no segregation, no bleeding and no stickiness in a flow state) is solved.
In conclusion, the concrete filled steel tube has the characteristic of high strength, and mainly shows that the compressive strength is greater than 80% of the designed strength in 3 days and is greater than 115% of the designed strength in 28 days; the high strength not only ensures the structural quality, but also shortens the intermittent period of the working procedure by the high strength of 3 days, thereby shortening the construction period, improving the construction efficiency, saving the cost and generating considerable economic benefit.
The C70 self-compaction shrinkage-compensated concrete filled steel tube has the characteristics of low viscosity and high fluidity, and is mainly reflected in that the concrete mixture has good fluidityThe coating property, no segregation, no bleeding and no stickiness are realized; the slump is 250-270mm, the slump expansion is 670-700mm, and T500The pumping pressure and the construction risk are reduced due to the good workability of the concrete for 8-10s, and the equipment investment is reduced, so that the construction quality is ensured, and the construction cost is saved.
The C70 self-compacting shrinkage-compensating concrete filled steel tube also has the characteristic of shrinkage compensation, and the free expansion rate is more than 0 under the 28d closed environment; by scientifically selecting an expansion source and reasonably combining the expansion source, the period of an expansion peak value is shortened, the self-contraction of the concrete-filled steel tube is effectively compensated, the technical problem of debonding of the concrete and the inner wall of the steel tube is solved, and the volume stability of the concrete-filled steel tube is ensured.
In a word, all performance indexes (all performance indexes of concrete in the construction process and all performance indexes of a structure after construction) of the concrete structure meet the requirements of corresponding standard indexes, and the concrete structure is easy to construct and convenient to control the quality; in the face of the current situations of environmental protection and river sand resource shortage, the method is suitable for local conditions and local materials, and is suitable for wide application and popularization.
The foregoing is illustrative of the preferred embodiments of the present invention, and the present invention is not to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Any simple modification, equivalent change and modification of the above embodiments according to the technical spirit of the present invention still fall within the scope of the technical solution of the present invention.
Claims (10)
1. The C70 self-compacting shrinkage-compensating concrete filled steel tube is characterized in that the following materials are used per cubic meter of concrete: 450kg to 470kg of cement, 45kg to 70kg of micro-beads, 40kg to 55kg of silicon powder, 50kg to 55kg of composite expanding agent, 952kg to 1008kg of coarse aggregate, 730kg to 754kg of fine aggregate, 8.85kg to 9.75kg of high-performance water reducing agent and 163kg to 171kg of water.
2. The C70 self-compacting shrinkage-compensated steel tube concrete as set forth in claim 1, wherein: the micro-beads are spherical amorphous fly ash micro-beads, the thixotropic index of the micro-beads is 7.5,the sphere density and the bulk density were 2520kg/m3、650kg/m3The specific surface area is 1300m2Per kg, the activity index is 87 percent, the loss on ignition is 1.21 percent, and the water demand ratio is 98 percent;
the specification of the silicon powder is SF90 and above, and the specific surface area is not less than 15000m2Kg, activity index not less than 90%.
3. The C70 self-compacting shrinkage-compensated steel tube concrete as set forth in claim 1, wherein: the composite expanding agent is prepared from calcium oxide and magnesium oxide according to the following formula (2-4): (6-8) in mass ratio.
4. The C70 self-compacting shrinkage-compensated steel tube concrete as set forth in claim 1, wherein: the coarse aggregate is crushed stone of 5-16mm continuous gradation, and the crushing value is less than 18%.
5. The C70 self-compacting shrinkage-compensated steel tube concrete as set forth in claim 1, wherein: the coarse aggregate is prepared by mixing crushed stones with the weight ratio of 5-10 mm and 10-16 mm according to the ratio of (1-5): (9-5) in a ratio.
6. The C70 self-compacting shrinkage-compensated steel tube concrete according to claim 4 or 5, wherein: the crushed stone is crushed stone of basalt and limestone with the saturated uniaxial compressive strength of gravel or mother rock which is crushed by cobblestones and not lower than 105 MPa; when the coarse aggregate is prepared, one kind of the macadam can be adopted independently, and at least two kinds of mixed macadams which can be combined randomly can also be adopted.
7. The C70 self-compacting shrinkage-compensated steel tube concrete as set forth in claim 1, wherein: the fine aggregate is machine-made sand or natural river sand which is formed by crushing basalt and cobblestones, the specification of the fine aggregate is 0 mm-4.75 mm, and the fineness modulus is 2.8-3.0.
8. The C70 self-compacting shrinkage-compensating steel tube concrete as claimed in claim 1, wherein the high performance water reducing agent is composed of the following components by mass percent: 38-45% of water-reducing mother liquor, 11-22% of slump retaining agent, 10-17% of composite water-reducing slump retaining mother liquor, 0.08-0.2% of defoaming agent, 0.05-0.15% of composite defoaming air-entraining agent, 2-5% of white sugar, 2-4% of sodium gluconate, 1-3% of water-retaining agent and the balance of water.
9. The C70 self-compacting shrinkage-compensated steel tube concrete as set forth in claim 8, wherein: the water-reducing mother liquor is a composition of isobutylene alcohol polyoxyethylene ether and hydroxyethyl acrylate;
the slump retaining agent is one or a mixture of more than two of citric acid or sodium gluconate, sodium tripolyphosphate or sodium hexametaphosphate;
the composite water-reducing slump-retaining mother liquor is a copolymer of hydroxyethyl acrylate and methyl allyl polyoxyethylene ether, and the molecular weight of the copolymer is 5000-30000;
the defoaming agent is one or a mixture of more than two of C7-C22 high-carbon alcohol, polyether defoaming agent and organosilicon defoaming agent in any proportion;
the composite defoaming air entraining agent is one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, fatty alcohol-polyoxyethylene ether, sodium fatty alcohol-polyoxyethylene sulfonate and sodium fatty alcohol sulfate.
The water retaining agent is white powdery hydroxypropyl methyl cellulose ether.
10. The preparation method of the C70 self-compacting shrinkage-compensated steel tube concrete according to any one of claims 1-9, wherein the preparation method comprises the following steps: the method comprises the steps of firstly, respectively adding cement, silicon powder, a composite expanding agent, coarse aggregates, fine aggregates and fly ash or microbeads in a formula ratio into a mixer pot body for stirring, stirring for 20-40 seconds to fully and uniformly mix the aggregates and powder, then mixing water in a formula ratio with a high-performance water reducing agent to form a mixed solution, adding the mixed solution into the mixer pot body, and continuously stirring for 140-160 seconds to obtain the C70 self-compacting compensation shrinkage steel pipe concrete.
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| CN113149560A (en) * | 2021-04-27 | 2021-07-23 | 清华大学 | High-fluidity conductive concrete and preparation method thereof |
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| CN112979245A (en) * | 2021-03-15 | 2021-06-18 | 中国电建集团成都勘测设计研究院有限公司 | Airport pavement concrete for plateau area |
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| CN115259789A (en) * | 2022-07-20 | 2022-11-01 | 杭州惠居建筑科技有限公司 | High-thixotropy reinforced concrete for reinforcing thin plates and preparation method thereof |
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| CN115304326B (en) * | 2022-08-08 | 2023-10-20 | 杭萧钢构股份有限公司 | Shrinkage-compensating self-compacting concrete and preparation method thereof |
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| CN115504754A (en) * | 2022-10-18 | 2022-12-23 | 中铁大桥局集团有限公司 | Steel pipe concrete based on solid waste expansion and preparation method thereof |
| CN115504754B (en) * | 2022-10-18 | 2023-06-20 | 中铁大桥局集团有限公司 | Steel pipe concrete based on solid waste expansion and preparation method thereof |
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