CN111039626A - Lightweight aggregate ultrahigh-performance concrete and preparation method thereof - Google Patents
Lightweight aggregate ultrahigh-performance concrete and preparation method thereof Download PDFInfo
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- 239000011374 ultra-high-performance concrete Substances 0.000 title claims abstract description 63
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 58
- 239000010451 perlite Substances 0.000 claims abstract description 52
- 235000019362 perlite Nutrition 0.000 claims abstract description 52
- 239000004568 cement Substances 0.000 claims abstract description 45
- 239000000843 powder Substances 0.000 claims abstract description 44
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 24
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 24
- 239000000835 fiber Substances 0.000 claims abstract description 24
- 239000010959 steel Substances 0.000 claims abstract description 24
- 239000002245 particle Substances 0.000 claims abstract description 22
- 229910021487 silica fume Inorganic materials 0.000 claims abstract description 13
- 238000001723 curing Methods 0.000 claims description 35
- 238000002156 mixing Methods 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 20
- 238000001816 cooling Methods 0.000 claims description 19
- 239000000203 mixture Substances 0.000 claims description 19
- 239000011268 mixed slurry Substances 0.000 claims description 14
- 238000006467 substitution reaction Methods 0.000 claims description 12
- 238000012360 testing method Methods 0.000 claims description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 10
- 230000000694 effects Effects 0.000 claims description 10
- 238000001029 thermal curing Methods 0.000 claims description 10
- 239000006004 Quartz sand Substances 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- 238000012856 packing Methods 0.000 claims description 7
- 238000013461 design Methods 0.000 claims description 6
- 239000011398 Portland cement Substances 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 5
- 239000011402 Portland pozzolan cement Substances 0.000 claims description 3
- 239000011401 Portland-fly ash cement Substances 0.000 claims description 3
- 239000002893 slag Substances 0.000 claims description 3
- 238000012795 verification Methods 0.000 claims description 3
- 239000004567 concrete Substances 0.000 abstract description 19
- 239000000463 material Substances 0.000 abstract description 9
- 239000004566 building material Substances 0.000 abstract description 2
- 239000002994 raw material Substances 0.000 description 15
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- 238000010521 absorption reaction Methods 0.000 description 2
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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
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/04—Silica-rich materials; Silicates
- C04B14/14—Minerals of vulcanic origin
- C04B14/18—Perlite
- C04B14/185—Perlite expanded
-
- 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
- C04B28/021—Ash cements, e.g. fly ash cements ; Cements based on incineration residues, e.g. alkali-activated slags from waste incineration ; Kiln dust 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
- 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
- C04B28/08—Slag 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
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/02—Selection of the hardening environment
- C04B40/0263—Hardening promoted by a rise in temperature
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/24—Sea water resistance
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- 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
- C04B2111/40—Porous or lightweight materials
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- 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
- C04B2201/52—High compression strength concretes, i.e. with a compression strength higher than about 55 N/mm2, e.g. reactive powder concrete [RPC]
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Abstract
The invention relates to the technical field of building materials, in particular to lightweight aggregate ultrahigh-performance concrete and a preparation method thereof. The invention provides a lightweight aggregate ultra-high performance concrete which is prepared from the following components in parts by weight: 220-400 parts of cement; 100-120 parts of silica fume; 5-150 parts of expanded pearl powder; 220-260 parts of expanded perlite; 15-20 parts of a water reducing agent; 76-93 parts of steel fiber; 130-160 parts of water; the particle size of the expanded pearl powder is less than 0.075 mm; the particle size range of the expanded perlite is 0.075-0.6 mm. The lightweight ultrahigh-performance concrete designed and prepared by the invention has excellent density performance, can meet the requirements of super-large span bridges, ultrahigh-rise buildings, serving concrete members in marine complex environments and the like on the lightweight ultrahigh-strength ultrahigh-durability cement-based material, and has higher popularization value.
Description
Technical Field
The invention relates to the technical field of building materials, in particular to lightweight aggregate ultrahigh-performance concrete and a preparation method thereof.
Background
The lightweight aggregate concrete is characterized in that the apparent density is controlled to 1950kg/m by adding lightweight aggregate3The following concrete, lightweight aggregate concrete, has the advantages of high specific strength, heat preservation, heat insulation and the like, and is widely applied to various load-bearing and non-load-bearing structures. Super large span bridges, super high-rise buildings put higher requirements on the strength and durability of concrete, however, compared with traditional gravel aggregate, the mechanical property of lightweight aggregate is low, so that the lightweight aggregate concrete has the defects of low strength and poor durability, and the development and application of the lightweight aggregate concrete are limited.
The existing research focuses on the performance enhancement (improvement of mechanical properties) of lightweight aggregates, and the commonly used technical means include: (1) the lightweight aggregate with low water absorption, high strength and high quality is selected, so that the raw material cost of the lightweight aggregate concrete is improved; (2) a layer of compact shell is prefabricated on the surface of the lightweight aggregate by using a cement-based material, so that the strength of the lightweight aggregate is improved; (3) by adding the auxiliary cementing material, the performance of the interface transition zone of the lightweight aggregate and the cement paste is improved (the interface transition zone is used as a shell of the lightweight aggregate) so as to improve the performance of the lightweight aggregate concrete. However, the technical means puts higher requirements on the lightweight aggregate pretreatment process and the construction process, the preparation process is complex, and the fact that the lightweight aggregate concrete is used as a weak link is not fundamentally solved, so that the performance of the prepared lightweight aggregate concrete is improved to a limited extent.
Disclosure of Invention
The invention aims to provide lightweight aggregate ultrahigh-performance concrete and a new idea for preparing the same. The invention uses expanded perlite with wide sources, high water absorption and poor strength as lightweight aggregate (filler), and reduces the stress concentration phenomenon of concrete by improving the homogeneity of slurry, thereby realizing the preparation of the lightweight aggregate ultrahigh-performance concrete with ultrahigh strength, high toughness, high impact resistance and excellent durability; on the other hand, compared with the existing research on lightweight aggregate concrete, the lightweight aggregate concrete prepared by the research has more excellent performance.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a lightweight aggregate ultrahigh-performance concrete which is prepared from the following components in parts by weight:
the particle size of the expanded perlite is 0.075-0.6 mm;
the particle size of the expanded pearl powder is less than 0.075 mm.
Preferably, the cement is portland cement, pozzolan cement, fly ash cement, or slag cement; the average particle size of the cement was 10.6 μm.
Preferably, the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent; the water reducing rate of the water reducing agent exceeds 35 percent.
Preferably, the steel fibers are long straight steel fibers; the diameter of the steel fiber is 0.1-0.3 mm, the length is 6-15 mm, and the tensile strength is more than 1600 MPa.
Preferably, the design method for determining the lightweight aggregate ultra-high performance concrete formula comprises the following steps:
(1) based on a tight packing theory, a reference group combination ratio with a compact structure is designed by utilizing a ModifiedAndreasen and dandersen model;
(2) establishing a functional relation between the substitution amount of the expanded pearl powder and the expanded perlite and the ultrahigh performance density and strength according to an effect surface method, and determining the mixing amount of the expanded pearl powder and the expanded perlite according to the performance requirements;
(3) and (3) carrying out test verification on the proportion designed by the effect surface method to obtain the mixing proportion of the lightweight aggregate ultrahigh-performance concrete.
Preferably, the expanded pearl powder is used to replace part of cement, and the expanded perlite is used to replace part or all of quartz sand.
Preferably, the formula of the lightweight aggregate ultrahigh-performance concrete in the step (3) is as follows:
when the density of the lightweight aggregate ultrahigh-performance concrete is 1700 grade, the lightweight aggregate ultrahigh-performance concrete is prepared from the following components in parts by weight: 241 parts of cement, 112 parts of silica fume, 147 parts of expanded pearl powder, 244 parts of expanded perlite, 146 parts of water, 18 parts of water reducing agent and 93 parts of steel fiber;
when the density of the lightweight aggregate ultrahigh-performance concrete is 1800 grade, the lightweight aggregate ultrahigh-performance concrete is prepared from the following components in parts by weight: 388 parts of cement, 102 parts of silica fume, 47 parts of expanded pearl powder, 223 parts of expanded perlite, 137 parts of water, 16 parts of water reducing agent and 85 parts of steel fiber.
The invention also provides a preparation method of the lightweight aggregate ultrahigh-performance concrete in the technical scheme, which comprises the following steps:
(1) firstly mixing cement, silica fume, expanded pearl powder and expanded perlite to obtain a mixture;
(2) secondly mixing the mixture with a water reducing agent and water to obtain mixed slurry;
(3) thirdly mixing the mixed slurry with steel fibers to obtain a blank;
(4) and carrying out thermal curing on the green body to obtain the lightweight ultrahigh-performance concrete.
Preferably, the thermal curing comprises a first stage of hot water curing and a second stage of dry high-temperature curing which are sequentially carried out.
Preferably, the first-stage hot water curing comprises a pre-curing stage, a heating stage, a constant temperature stage and a cooling stage which are sequentially carried out;
the temperature of pre-curing in the first-stage hot water curing is 20-40 ℃, and the time is 12-36 hours;
the temperature rise rate of the temperature rise stage in the first-stage hot water curing is 0.1-1 ℃/min;
the temperature of the constant temperature stage in the first-stage hot water curing is 90-100 ℃, and the time is 6-8 hours;
the cooling rate of the cooling stage in the first-stage hot water curing is 0.23-0.3 ℃/min;
the second stage of dry high-temperature curing comprises a heating stage, a constant temperature stage and a cooling stage which are sequentially carried out;
the temperature rise rate of the temperature rise stage in the second-stage drying high-temperature curing is 5-10 ℃/min;
the constant temperature time of the constant temperature stage in the second stage drying high-temperature curing is 2-3 h;
and the cooling rate of the cooling stage in the second stage of drying high-temperature curing is 0.1-0.5 ℃/min.
The invention provides a lightweight aggregate ultrahigh-performance concrete which is prepared from the following components in parts by weight: 220-400 parts of cement; 100-120 parts of silica fume; 5-150 parts of expanded pearl powder; 220-260 parts of expanded perlite; 15-20 parts of a polycarboxylic acid-based high-efficiency water reducing agent; 76-93 parts of steel fiber; 130-160 parts of water. The particle size of the expanded pearl powder is less than 0.075mm, and the particle size of the expanded perlite is 0.075-0.6 mm. The invention uses expanded perlite with wide source and low performance as a light aggregate component, and the expanded perlite and the expanded pearl powder are uniformly dispersed in concrete by controlling the grain diameter and the addition of the expanded perlite and the expanded pearl powder and the cooperation of other raw materials, so that a stress-dispersed geometric structure is constructed; the stress concentration phenomenon is further avoided by adding the steel fiber, and the lightweight aggregate ultrahigh-performance concrete with ultrahigh strength, high toughness, high impact resistance and excellent durability is obtained. Compared with the prior art, the invention does not start from the reinforcement of the lightweight aggregate (traditional lightweight aggregates such as ceramsite and the like), and does not need to start from the reinforcement of the lightweight aggregateThe high-strength lightweight aggregate needs to be used, and the stress concentration phenomenon is reduced by improving the homogeneity of the cement-based material, so that the cement-based material with low density and high strength is obtained. The lightweight aggregate ultrahigh-performance concrete provided by the invention has the advantages that the raw materials are widely and easily available, the cost of the expanded perlite used as the lightweight aggregate is low, and the expanded perlite is easy to treat; the lightweight ultrahigh-performance concrete designed and prepared by the invention has excellent density performance (the density is less than 1700 kg/m)3The compressive strength is more than 150MPa, the 28-day electric flux is less than 100C), the requirements of super-large span bridges, super high-rise buildings, serving concrete members in marine complex environments and the like on light weight, super high strength and super high durability of cement-based materials can be met, and the method has high popularization value.
The invention also provides a preparation method of the lightweight aggregate ultrahigh-performance concrete, and the lightweight aggregate and other raw materials are not required to be pretreated by other processes, so that the preparation process is simplified, and the production period is shortened.
Drawings
FIG. 1 is a flow chart of the design of ultra-high performance coagulation of lightweight aggregate according to the present invention;
FIG. 2 is a diagram showing the substitution relationship among expanded perlite, expanded pearl powder and other raw materials;
FIG. 3 is a plot of experimental points for determining an experimental protocol using the effect surface method;
FIG. 4 is a schematic view of a thermal curing regime;
FIG. 5 is an electric flux of the lightweight-aggregate ultrahigh-performance concrete prepared in example 1.
Detailed Description
The invention provides a lightweight aggregate ultrahigh-performance concrete which is prepared from the following components in parts by weight:
the particle size of the expanded perlite is 0.075-0.6 mm;
the particle size of the expanded pearl powder is less than 0.075 mm.
In the present invention, all the raw material components are commercially available products well known to those skilled in the art unless otherwise specified.
In the invention, the raw materials for preparing the lightweight aggregate ultrahigh-performance concrete comprise 220-400 parts by weight of cement, preferably 220-260 parts by weight of cement, and more preferably 240 parts by weight of cement. In the present invention, the cement is preferably portland cement, pozzolan cement, fly ash cement, or slag cement, and more preferably ordinary portland cement; the average particle size of the cement is preferably 10.6 μm. In the invention, the cement has the functions of participating in hydration reaction and physical filling.
In the invention, the raw materials for preparing the lightweight aggregate ultrahigh-performance concrete comprise 100-120 parts by weight of silica fume, preferably 112 parts by weight of cement. In the invention, the silica fume plays roles of volcanic ash effect and filling effect.
In the invention, the cement is used as a reference in parts by weight, and the raw materials for preparing the lightweight aggregate ultrahigh-performance concrete comprise 5-150 parts of expanded pearl powder, and more preferably 47-147 parts; the particle size of the expanded pearl powder is preferably less than 0.075 mm. In the present invention, the preparation method of the expanded pearl powder preferably includes: carrying out ball milling on expanded perlite sold in the market, and screening to obtain expanded pearl powder with the particle size of less than 0.075 mm. In the invention, the rotation speed of the ball milling is preferably 30-40 r/min, and the time is preferably 0.3-1.0 h.
In the invention, the cement is used as a reference in parts by weight, the raw materials for preparing the lightweight aggregate ultrahigh-performance concrete comprise 220-260 parts of expanded perlite, preferably 223-244 parts of expanded perlite, and the particle size of the expanded perlite is 0.075-0.6 mm. In the present invention, the method for preparing the expanded perlite preferably comprises: and carrying out ball milling on the expanded perlite sold in the market, and screening to obtain the expanded perlite with the particle size of 0.075-0.6 mm. In the invention, the rotation speed of the ball milling is preferably 30-40 r/min, and the time is preferably 0.1-0.3 h.
In the invention, the raw materials for preparing the lightweight aggregate ultrahigh-performance concrete comprise 15-20 parts of water reducing agent, preferably 16-18 parts of cement by weight. In the invention, the water reducing agent is preferably a polycarboxylic acid water reducing agent, and the solid content of the water reducing agent is preferably 18%; the water reducing rate of the water reducing agent exceeds 35 percent.
In the invention, the raw materials for preparing the lightweight aggregate ultrahigh-performance concrete comprise 76-93 parts by weight of steel fibers, preferably 85-93 parts by weight of cement. In the present invention, the steel fibers are preferably long straight steel fibers; the diameter of the steel fiber is preferably 0.1-0.3 mm, and more preferably 0.2 mm; the length is preferably 6-15 mm, and more preferably 13 mm; the tensile strength is preferably 1600MPa or more, more preferably 2400 MPa.
In the invention, the raw materials for preparing the lightweight aggregate ultrahigh-performance concrete comprise 130-160 parts of water, preferably 137-146 parts of water based on the weight parts of the cement.
In the present invention, the design method for determining the lightweight aggregate ultra-high performance concrete formulation preferably includes the steps of:
(1) based on a tight packing theory, a reference group combination ratio with a compact structure is designed by utilizing a ModifiedAndreasen and dandersen model;
(2) establishing a functional relation between the substitution amount of the expanded pearl powder and the expanded perlite and the ultrahigh performance density and strength according to an effect surface method, and determining the mixing amount of the expanded pearl powder and the expanded perlite according to the performance requirements;
(3) and (3) carrying out test verification on the proportion designed by the effect surface method to obtain the mixing proportion of the lightweight aggregate ultrahigh-performance concrete.
The design idea of the lightweight aggregate ultra-high performance concrete (UHPC) of the present invention is as shown in fig. 1, and the present invention aims to establish a homogeneous structure preventing stress concentration instead of preparing UHPC by increasing the strength of the lightweight aggregate.
According to the invention, preferably, according to the theory of particle close packing, by using Modified Andersen and Andersen, a reasonable substitution relationship is established by adjusting the particle size ranges of the expanded pearl powder filler and the expanded perlite lightweight aggregate (namely, the expanded pearl powder is used for replacing cement, and the expanded perlite is used for replacing quartz sand so as to ensure close packing compactness), and the method specifically comprises the following steps: firstly, preparing expanded perlite with the grain size of 0.075-0.6 mm and expanded pearl powder with the grain size of less than 0.075 mm; then, by a compact packing theory, using a Modifiedandreacen and dAndersen model to preliminarily establish a substitution relationship between the expanded perlite and the expanded pearl powder for other preparation raw materials, as shown in FIG. 2, as can be seen from FIG. 2, the substitution of the expanded pearl powder or the expanded perlite for cement and quartz sand respectively has little influence on the packing compactness of the system, so that the substitution of the expanded pearl powder for part of the cement and the substitution of the expanded perlite for part or all of the quartz sand are determined; wherein, the reference group combination ratio is shown in table 1.
TABLE 1 reference group combination ratio (kg/m)3)
After determining the substitution relationship of the expanded perlite and the expanded pearl powder to other preparation raw materials, the invention further determines the substitution amount of the expanded pearl powder light filler and the expanded perlite light aggregate according to an effect surface method, which specifically comprises the following steps:
(1) determining independent variables, independent variable value ranges and dependent variables: in the invention, the substitution amount of the expanded pearl powder light filler and the expanded perlite light aggregate is independent variable, the density (in absolute dry density) and the compressive strength of the cement-based material are dependent variables, and the independent variable, the constraint condition and the dependent variables are shown in a table 2;
TABLE 2 independent variables (including constraints) and dependent variables
(2) Design experiment, record results: determining a test scheme (shown in figure 3) by using a Charge Coupled Device (CCD) method (the central point is repeated for 3 times), totaling 11 mix proportions, carrying out a test, recording test data, and showing the test scheme and test results in a table 3;
TABLE 3 test protocol (kg/m)3) And result
(3) Establishing a model and evaluating the accuracy of the model, see table 4; based on the test result, fitting the regression model to obtain the relationship between the doping amount of the lightweight aggregate (filler) and the density and strength of the cement-based material, wherein the relationship comprises the following steps:
the density is 2424.00-280.65 multiplied by the cement quantity substituted by the expanded pearl powder-610.52 multiplied by the quartz sand quantity substituted by the expanded perlite;
the strength is 190.55659+6.77904 multiplied by the quantity of the expanded pearl powder substituted by cement-68.73060 multiplied by the quantity of the expanded perlite substituted by quartz sand +7.33333 multiplied by the quantity of the expanded pearl powder substituted by cement multiplied by the quantity of the expanded perlite substituted by quartz sand-98.93519 multiplied by the quantity of the expanded pearl powder substituted by cement +18.98333 multiplied by the quantity of the expanded perlite substituted by quartz sand;
TABLE 4 evaluation results of model accuracy
Wherein, the F values of the models are 2160.17 and 96.39 respectively, and the P value is less than 0.0001, which indicates that the models are extremely remarkable; the correction decision coefficients of the model are Adj-R respectively20.99 and 0.95; complex correlation coefficient Pre-R20.99 and 0.91, indicating that the model fit is high; the result shows that the model has good reliability and high analysis reliability.
(4) Setting a range and solving, wherein different lightweight aggregate concrete designed by the invention is detailed in a table 5;
TABLE 5 solving conditions (kg/m)3)
Obtaining a formula of the lightweight aggregate ultrahigh-performance concrete according to the functional relationship and preset target performance, wherein the formula is specifically shown in table 6;
TABLE 6 formulation (kg/m) of lightweight aggregate ultra-high performance concrete3)
The invention also provides a preparation method of the lightweight aggregate ultrahigh-performance concrete in the technical scheme, which comprises the following steps:
(1) firstly mixing cement, silica fume, expanded pearl powder and expanded perlite to obtain a mixture;
(2) secondly mixing the mixture with a water reducing agent and water to obtain mixed slurry;
(3) thirdly, mixing the mixed slurry with steel fibers to prepare a blank, and thus obtaining a blank body;
(4) and carrying out thermal curing on the green body to obtain the lightweight aggregate ultrahigh-performance concrete.
The cement, the silica fume, the expanded perlite, the expanded pearl powder and the quartz sand are mixed for the first time to obtain a mixture. In the invention, the first mixing is preferably carried out under the condition of stirring, and the stirring speed is preferably 135-145 r/min; the stirring time is preferably 2-5 min, and more preferably 3 min. In the invention, the addition of the expanded perlite and the expanded pearl powder can obviously improve the friction force between the mixture and the inner wall of the stirrer, and simultaneously improve the friction force and the shearing force between the mortar mixture, and the larger friction force and the shearing force are beneficial to improving the dispersion speed of water and the water reducing agent, so that the concrete can be stirred into uniform slurry.
After the mixture is obtained, the mixture, the water reducing agent and the water are subjected to second mixing to obtain mixed slurry. In the invention, water and the water reducing agent are preferably mixed firstly, and then the obtained mixed solution is mixed with the mixture.
After the mixed slurry is obtained, the mixed slurry and the steel fiber are subjected to third mixing to prepare a blank, and a blank is obtained. After the mixed slurry is obtained, the mixed slurry is preferably stirred at a high speed, and then the steel fiber is added for mixing. In the invention, the stirring speed of the high-speed stirring is preferably 270-290 r/min, and the time is preferably 2 min. The invention improves the homogeneity of the mixed slurry by high-speed stirring.
In the invention, the third mixing is preferably carried out under the condition of stirring, and the stirring speed is preferably 135-145 r/min; the stirring time is preferably 2-3 min, and more preferably 2 min. The final addition of steel fibers in the invention can improve the dispersion uniformity of each material in the concrete.
The preparation process is not particularly limited in the invention, and the preparation process of the ultra-high performance concrete well known in the field can be adopted.
After the sample is obtained, the sample is subjected to thermal curing to obtain the lightweight aggregate ultrahigh-performance concrete. In the present invention, the thermal curing preferably includes a first stage of hot water curing and a second stage of dry high temperature curing which are sequentially performed;
the first-stage hot water curing preferably comprises a pre-curing stage, a heating stage, a constant temperature stage and a cooling stage which are sequentially carried out; the pre-curing temperature is preferably 20-40 ℃, and the time is preferably 12-36 h; the rate of the temperature rise stage is preferably 0.1-1 ℃/min; the temperature of the constant temperature stage is preferably 90-100 ℃, and the time is preferably 6-8 h; the cooling rate of the cooling stage is preferably 0.23-0.3 ℃/min;
the second-stage drying high-temperature curing preferably comprises a heating stage, a constant-temperature stage and a cooling stage which are sequentially carried out; the heating rate of the heating stage is preferably 5-10 ℃/min; in the specific embodiment of the invention, the temperature is preferably kept constant for 2-3 h every time the temperature is raised to 50 ℃; in the invention, the temperature of the constant temperature stage is preferably 250 ℃, and the constant temperature time is preferably 2-3 h; the cooling rate of the cooling stage is preferably 0.1-0.5 ℃/min.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
(1) Stirring 405kg P.O 42.5.5R ordinary portland cement (with the average particle size of 10.6 μm), 188kg silica fume, 248kg expanded pearl powder (with the particle size of 0-0.075 mm) and 410kg expanded perlite (with the particle size of 0.075-0.6 mm) at the speed of 140R/min for 3min to obtain a mixture;
(2) mixing 30kg of polycarboxylic acid water reducing agent (with the solid content of 18%) and 246kg of water, slowly adding the mixture into the mixture obtained in the step (1), and stirring the mixture at the speed of 140r/min for more than 5min to obtain mixed slurry;
(3) stirring the mixed slurry at the speed of 280r/min for 2min, then adding long straight steel fibers (the diameter is 0.2mm, the length is 13mm, and the tensile strength is 2400MPa), stirring at the speed of 140r/min for 2min, forming and demolding to obtain a blank;
(4) carrying out thermal curing on the green body according to a curing system shown in figure 4 to obtain the lightweight aggregate ultrahigh-performance concrete; the specific mode of the thermal curing is as follows: pre-curing for 24 hours at the temperature of 20 ℃; then raising the temperature to 90 ℃ at the heating rate of 1 ℃/min, and preserving the heat for 6 hours; then the temperature is reduced to 20 ℃ at the cooling rate of 0.23 ℃/min, then the temperature is increased to 250 ℃ at the rate of 5 ℃/min (the temperature is kept constant for 2h at each temperature rise of 50 ℃), and finally the temperature is reduced to room temperature at the cooling rate of 0.35 ℃/min for testing.
The obtained lightweight aggregate ultra-high performance concrete is 1600 grades, and the density is 1580kg/m3The compressive strength is 164.9 MPa.
Test examples
The durability (measured by electric flux and chloride ion diffusion depth) of the lightweight aggregate ultrahigh-performance concrete prepared in example 1 was tested, and as shown in fig. 5, it can be seen from fig. 5 that the chloride ion penetration depth of the lightweight aggregate ultrahigh-performance concrete prepared according to the present invention after the conventional curing for 28 days was 0mm, and the electric flux was < 100C, which indicates that the lightweight aggregate ultrahigh-performance concrete has excellent durability in addition to the advantages of lightweight ultrahigh strength.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. The lightweight aggregate ultrahigh-performance concrete is characterized by being prepared from the following components in parts by weight:
the particle size of the expanded pearl powder is less than 0.075 mm;
the particle size range of the expanded perlite is 0.075-0.6 mm.
2. The lightweight-aggregate ultrahigh-performance concrete according to claim 1, wherein the cement is portland cement, pozzolan cement, fly ash cement, or slag cement; the average particle size of the cement was 10.6 μm.
3. The lightweight aggregate ultrahigh-performance concrete according to claim 1, characterized in that the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent; the water reducing rate of the water reducing agent exceeds 35 percent.
4. The lightweight aggregate ultrahigh performance concrete according to claim 1, characterized in that the steel fibers are long straight steel fibers; the diameter of the steel fiber is 0.1-0.3 mm, the length is 6-15 mm, and the tensile strength is more than 1600 MPa.
5. The lightweight aggregate ultrahigh-performance concrete according to any one of claims 1 to 4, wherein the design method for determining the formula of the lightweight aggregate ultrahigh-performance concrete comprises the following steps:
(1) based on a tight packing theory, designing a reference group combination ratio with a compact structure by using a Modified Andersen and Andersen model;
(2) establishing a functional relation between the substitution amount of the expanded pearl powder and the expanded perlite and the ultrahigh performance density and strength according to an effect surface method, and determining the mixing amount of the expanded pearl powder and the expanded perlite according to the performance requirements;
(3) and (3) carrying out test verification on the proportion designed by the effect surface method to obtain the mixing proportion of the lightweight aggregate ultrahigh-performance concrete.
6. The lightweight aggregate ultrahigh-performance concrete as claimed in claim 5, wherein expanded pearl powder is used in place of part of cement, and expanded perlite is used in place of part or all of quartz sand.
7. The lightweight aggregate ultrahigh-performance concrete according to claim 5, wherein the formula of the lightweight aggregate ultrahigh-performance concrete in the step (3) is as follows:
when the density of the lightweight aggregate ultrahigh-performance concrete is 1700 grade, the lightweight aggregate ultrahigh-performance concrete is prepared from the following components in parts by weight: 244 parts of cement, 112 parts of silica fume, 147 parts of expanded pearl powder, 244 parts of expanded perlite, 146 parts of water, 18 parts of water reducing agent and 93 parts of steel fiber;
when the density of the lightweight aggregate ultrahigh-performance concrete is 1800 grade, the lightweight aggregate ultrahigh-performance concrete is prepared from the following components in parts by weight: 388 parts of cement, 102 parts of silica fume, 47 parts of expanded pearl powder, 223 parts of expanded perlite, 137 parts of water, 16 parts of water reducing agent and 85 parts of steel fiber.
8. The method for preparing the lightweight aggregate ultrahigh-performance concrete as claimed in any one of claims 1 to 7, which is characterized by comprising the following steps:
(1) firstly mixing cement, silica fume, expanded pearl powder and expanded perlite to obtain a mixture;
(2) secondly mixing the mixture with a water reducing agent and water to obtain mixed slurry;
(3) thirdly mixing the mixed slurry with steel fibers to obtain a blank;
(4) and carrying out thermal curing on the green body to obtain the lightweight ultrahigh-performance concrete.
9. The method as claimed in claim 8, wherein the thermal curing comprises a first stage of hot water curing and a second stage of dry high-temperature curing which are sequentially performed.
10. The preparation method according to claim 9, wherein the first-stage hot water curing comprises a pre-curing stage, a temperature-raising stage, a constant-temperature stage and a temperature-lowering stage which are sequentially carried out;
the temperature of pre-curing in the first-stage hot water curing is 20-40 ℃, and the time is 12-36 hours;
the temperature rise rate of the temperature rise stage in the first-stage hot water curing is 0.1-1 ℃/min;
the temperature of the constant temperature stage in the first-stage hot water curing is 90-100 ℃, and the time is 6-8 hours;
the cooling rate of the cooling stage in the first-stage hot water curing is 0.23-0.3 ℃/min;
the second stage of dry high-temperature curing comprises a heating stage, a constant temperature stage and a cooling stage which are sequentially carried out;
the temperature rise rate of the temperature rise stage in the second-stage drying high-temperature curing is 5-10 ℃/min;
the constant temperature time of the constant temperature stage in the second stage drying high-temperature curing is 2-3 h;
and the cooling rate of the cooling stage in the second stage of drying high-temperature curing is 0.1-0.5 ℃/min.
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