CN114644489B - Normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete and preparation method thereof - Google Patents
Normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete and a preparation method thereof. The ultra-high performance concrete mainly comprises 800 to 1500 weight parts of powder material, 500 to 1500 weight parts of fine aggregate, 30 to 100 weight parts of additive, 112 to 240 weight parts of water and 234 to 468 weight parts of steel fiber. The invention determines the dosage of each raw material by a determination method of different powder materials and different fine aggregate mass ratios and a fiber compound mixing principle of steel fibers. The invention also provides a preparation method of the ultra-high performance concrete. The ultra-high performance concrete can reach the C200 strength grade through normal temperature curing, and the slump expansion degree reaches 600-800 mm, so that a plurality of inconveniences in the steam curing process are avoided, and the ultra-high performance concrete is suitable for C200 grade ultra-high performance concrete construction engineering requiring on-site pouring and normal temperature curing.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete and a preparation method thereof.
Background
As a new generation of cement-based composite material, the ultra-high performance concrete usually adopts cement, silica fume and ultrafine powder as cementing materials or fillers, takes quartz sand and other hard rocks as aggregates, and selects a low water-to-gel ratio (generally not more than 0.2) to construct a compact matrix. In order to improve the brittleness of the ultra-high performance concrete matrix, steel fibers are generally used for toughening to improve the ductility of the ultra-high performance concrete when being pressed and pulled. The compressive strength of the ultra-high performance concrete can reach 120MPa, and the ultra-high performance concrete has excellent durability and is gradually applied to special civil engineering structures such as large-span bridges and anti-explosion structures.
With the improvement of the mechanical property requirement of the engineering structure on the ultra-high performance concrete, the C180 and C200 grade ultra-high performance concrete gradually receives attention. When the strength grade of the ultra-high performance concrete reaches more than C180, because the water-to-cement ratio is generally not higher than 0.17 and the volume mixing amount of the steel fibers in the single-component concrete is generally not lower than 3.0%, the working performance is difficult to be considered on the premise of ensuring the mechanical property of the ultra-high performance concrete, and inconvenience is brought to construction. In order to achieve the required mechanical and working properties, the existing research mainly determines the mixing proportion of the ultra-high performance concrete by a test method or a theoretical model method. The test method is to design different mixing ratios and test, test the working performance and mechanical performance indexes of each group of ultra-high performance concrete, and then select the mixing ratio meeting the requirements. Because the components of the ultra-high performance concrete are complex, when the raw materials or performance indexes are changed, a large amount of tests are usually needed to determine the mixing ratio, and the debugging process is complicated and low-efficiency. The theoretical model is used for designing the composition and the dosage of the cementing material and the aggregate so as to realize the close packing of the cementing material and the aggregate particles and reduce the water amount sealed between the particles, thereby improving the working performance of the ultra-high performance concrete or reducing the water-cement ratio so as to improve the mechanical performance of the ultra-high performance concrete. The existing theoretical models can be divided into a discrete model and a continuous model. Discrete models require that the particle size ranges of the various particles (cement and aggregate) do not overlap, while the particle size ranges of powder materials generally have overlapping regions, and thus the method has limitations. The continuous model calculates the volume fractions of various particles based on theoretical particle distribution and particle size distribution of various particles, but the proportion between the cementing material and the aggregate is uniquely determined when the method is adopted, and the working performance of the ultra-high performance concrete is difficult to flexibly regulate and control. At present, the mechanical property and the working property of the C200 grade ultra-high performance concrete are difficult to guarantee simultaneously, and an effective method for guiding the mixing proportion design of the C200 grade ultra-high fluidity ultra-high performance concrete is lacked.
In order to fully exert the hydration activity and the pozzolanic activity of the cementitious material, the ultra-high performance concrete is generally cured by adopting a steam curing mode. The higher the curing temperature and the longer the curing time, the faster the hydration speed of the cementing material and the faster the strength development of the ultrahigh-performance concrete. The existing research shows that compared with the steam curing at 90 ℃, the compressive strength of the ultra-high performance concrete is reduced by about 20% and the flexural strength is reduced by about 10% when the standard curing is adopted for 28 d. However, in practical engineering, steam curing brings inconvenience to construction, and meanwhile, cost is remarkably increased, which limits popularization and application of large-volume cast-in-place ultrahigh-performance concrete to a certain extent. Therefore, how to realize the preparation and the pouring of the C200-grade high-fluidity ultrahigh-performance concrete under the normal-temperature curing condition has important practical significance.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide the normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete and the preparation method thereof, so that the mechanical property and the working property of the ultrahigh-performance concrete are considered, the curing process is simplified, and the technical support is provided for the on-site pouring and normal-temperature curing of the C200-grade ultrahigh-performance concrete.
In order to achieve the purpose, the invention adopts the following technical scheme:
a normal temperature curing C200-grade high-fluidity ultrahigh-performance concrete mainly comprises 800-1500 parts by weight of powder material, 500-1500 parts by weight of fine aggregate, 30-100 parts by weight of additive, 112-240 parts by weight of water and 234-468 parts by weight of steel fiber.
The powder material comprises cement, an auxiliary cementing material and an inert filler.
The cement is portland cement or ordinary portland cement;
preferably, the cement is Portland cement or ordinary Portland cement with the strength grade of 52.5.
The auxiliary cementing material is one or more of powdery materials with hydration activity or volcanic ash activity, such as silica fume, mineral powder, fly ash and the like;
the median particle size of the particles of the supplementary cementitious material is not greater than the median particle size of the particles of cement.
The inert filler is one or more of powder materials such as quartz powder, limestone powder and the like;
the median particle size of the particles of the inert filler is not greater than the median particle size of the particles of cement.
The fine aggregate is one or more of quartz sand, corundum sand, river sand and other aggregates.
The fine aggregate is graded continuous aggregate or single-particle-grade aggregate with various particle sizes;
preferably, the fine aggregate is one or more of quartz sand, corundum sand and other hard aggregates.
The particle size of the fine aggregate is not more than 2.5mm.
The mass ratio of the powder material to the fine aggregate is 0.8-2:1.
The mass ratio of the water to the powder material is 0.14-0.16.
The additive is a mixture of a water reducing agent or a mixture of the water reducing agent and more than one of a defoaming agent, an early strength admixture, a retarder and the like;
preferably, the water reducing agent is a polycarboxylic acid high-performance water reducing agent.
The steel fiber is microfilament steel fiber, the diameter of the microfilament steel fiber is 0.1-0.3 mm, and the length-diameter ratio of the microfilament steel fiber is 30-100.
The mixing amount of the steel fiber is not less than 3% of the volume of the ultra-high performance concrete.
The steel fibers are preferably steel fibers with different length-diameter ratio specifications.
Specifically, the mass ratio between different kinds of powder is determined by the following method:
the first step is as follows: selecting the type of powder material to form a powder system; testing the particle size distribution of various powder materials;
the second step is that: determining the granularity interval of the powder system;
the third step: dividing the granularity interval in which the powder material is positioned into sub-intervals, and calculating the theoretical value of the volume content of the powder in each sub-interval by adopting a powder distribution formula;
the fourth step: presetting the volume of each powder material, calculating the design value of the powder volume in each subinterval, and selecting the volume content of each powder when the square sum of the difference between the theoretical value and the design value of the powder volume in each subinterval is minimum;
the fifth step: and testing the apparent density of various powder materials, and calculating the mass ratio among the various powder materials in the system.
Further, for a powder system composed of X powder materials, the particle size interval of the system is determined by the following method: the particle size value when the cumulative particle size of the x-th powder particle reaches 95% is recorded as the characteristic of the powder xParticle size number
(for example, the characteristic particle size of the first powder
Characteristic particle size value of the second powder
Characteristic particle size value of the third powder
…, the characteristic particle size of the x-th powder
) (ii) a X kinds of powder materials have X characteristic particle size values, and the maximum value of the X characteristic particle size values is recorded as the characteristic particle size of the powder material system, namely
The particle size interval of the powder system is marked as
Further, the number of subintervals is the same as the type of powder material: for a binary system P consisting of two powder materials 1 -P 2 (median particle diameter of particles)
Is greater than
) If there is no overlapping region between the particle sizes of the two powders (powder P) 2 Median minimum particle size value
Not less than powder P 1 Median maximum particle size value
) Then, the powder P is used 2 Median minimum particle diameter value
Is a critical point, P is 1 -P 2 Particle size interval of the system
Division into subintervals I:
and sub-interval II:
if P 1 -P 2 The two powder particle size regions in the system have an overlapping region (powder P) 2 Median minimum particle diameter value
Smaller than powder P 1 Median maximum particle size value
) Then, the powder P is used 1 Middle diameter of
As critical point, the particle size of the powder is divided into
Divided into two sub-intervals
And
for ternary system P 1 -P 2 -P 3 (P 1 、P 2 、P 3 The median diameter of the particles increases in order), which is first regarded as P 1 -P 2-3 Binary-like system (in this case P 2 And P 3 Viewed as a mixed particle System P 2-3 ，P 2-3 The particle system is in the particle size interval of
). According to the powder P 1 And mixed powder P 2-3 Whether the granularity interval has an overlapping region or not is judged by dividing P according to the interval division method of a binary system 1 -P 2-3 The system granularity interval is divided into a subinterval I and a subinterval II; within interval II, according to P 2 、P 3 Whether the granularity intervals of the two powder materials are overlapped or not is judged, and the interval II is further divided into subintervals II 1 And sub-interval II 2 I.e. P 1 -P 2 -P 3 The system granularity interval is finally divided into I, II 1 And II 2 Three subintervals. For the quaternary and above systems, the subinterval division method is the same as above.
Further, the powder distribution formula is
Further, the design value of the volume of the powder in the subinterval is determined by the following method: for a powder system (with X sub-intervals) composed of X powder materials, when the volume content of each powder material is set (the sum of the volumes of the powder materials is 100%), the X powder material is in the ith sub-interval [ i [ i ] 1 ,i 2 ]In volume content of
Wherein V Px Is a set value of the volume content of the x-th powder material,
the particle size distribution curve of the x-th powder is in the interval [ i 1 ,i 2 ]The volume fraction of the powder contained therein. The sum of the volumes of all X powder materials in the subinterval i is
The design value of the powder volume in the subinterval i is shown as
The method for calculating the design value of the powder volume in other subintervals is the same as the above.
Further, the volume content of each type of powder is determined by the following steps: for a powder system containing X subintervals, firstly, calculating a theoretical value V of the volume content of the powder in each subinterval PT (ii) a Secondly, presetting the volume content of various powder materials (the sum of the volumes of the various powder materials is 100 percent), and calculating the design value V of the powder volume in each subinterval PM . Then, adjusting the set value of the volume content of each powder material to ensure that the theoretical value V of the volume of the powder in each subinterval PT And design value V PM Sum of squares of the differences R P At a minimum, wherein
The mass ratio among the fine aggregates with different granularity specifications is determined by the following method:
the first step is as follows: selecting fine aggregate types to form an aggregate system, and testing the particle size distribution of various fine aggregates;
the second step is that: determining a granularity interval where the fine aggregate is located;
the third step: dividing the granularity interval in which the fine aggregate is positioned into sub-intervals, and calculating the volume content of the fine aggregate in each sub-interval by adopting a fine aggregate distribution formula;
the fourth step: presetting the volume of various fine aggregates, calculating the design value of the volume of the fine aggregates in each subinterval, and determining the volume content of the various fine aggregates when the square sum of the difference between the theoretical value and the design value of the volume of the aggregates in each subinterval is minimum;
the fifth step: and testing the apparent density of various fine aggregates, and calculating the mass ratio among the various fine aggregates in the system.
Further, for an aggregate system composed of fine aggregates with a Y-granularity specification, the granularity interval in which the system is located is determined by the following steps: the value of the particle diameter at which the cumulative particle size of the y-th fine aggregate particles reached 10% was regarded as the characteristic particle diameter
The particle diameter at which the cumulative particle size of the particles reached 95% was taken as the characteristic particle diameter
Characteristic particle size of fine aggregate system
The particle size interval in which the fine aggregate system is located is marked as
Furthermore, the method for dividing the fine aggregate subintervals is consistent with that of the powder material.
Further, the fine aggregate distribution formula is
When the jth sub-interval in the fine aggregate system is [ j1, j 2 ]The theoretical value of the aggregate volume content in the subinterval is
Further, the design value of the volume of the aggregate in the subinterval is determined by the following method: for an aggregate system (with Y sub-intervals) composed of Y types of fine aggregates, after the volume content of each type of fine aggregate is set, the Y type of fine aggregate is in the jth sub-interval [ j1, j 2 ]In volume fraction of
Wherein V Ay Is the set value of the volume content of the y type fine aggregate,
the particle size distribution curve of the y type fine aggregate is in the interval [ j 1 ,j 2 ]The volume fraction of the aggregate contained therein. The sum of the volumes of all Y fine aggregates in the subinterval j is
The design value of the fine aggregate volume in the subinterval j is shown as
The method for calculating the design value of the fine aggregate volume in other subintervals is the same as the above.
Further, the volume content of each type of fine aggregate is determined by the following steps: for a fine aggregate system containing Y subintervals, firstly, calculating a theoretical value V of the volume content of the fine aggregate in each subinterval AT (ii) a Secondly, the volume content of various fine aggregates is preset, so that the sum of the volumes of the various fine aggregates is
The ultra-high performance concrete is prepared by compounding steel fibers with different length-diameter ratios, and the proportion of the steel fibers with various specifications meets the compounding principle: for two aspect ratio specification steel fiber system F 1 -F 2 (F 2 Aspect ratio greater than F 1 ) Steel fiber F 2 And F 1 The volume ratio of (A) is 0.25 to 0.5. For three length-diameter ratio specification steel fiber system F 1 -F 2 -F 3 (F 1 、F 2 、F 3 Length-diameter ratio is increased in order), steel fiber F 2 And F 1 Is 0.2 to 0.35 in a volume ratio of (1,F) 3 And F 2 The volume ratio of (1) is 0.2-0.35.
A preparation method of normal temperature curing C200-grade high-fluidity ultrahigh-performance concrete comprises the following steps:
(1) Determining the mixing ratio of raw materials in the ultra-high performance concrete;
(2) Stirring the raw materials.
The mixing proportion of the raw materials in the ultra-high performance concrete is determined by the following method:
s1: determining the mass ratio of different types of powder materials in the ultra-high performance concrete;
s2: determining the mass ratio of different types of fine aggregates in the ultra-high performance concrete;
s3: designing the water consumption and the mass ratio of the powder material to the fine aggregate;
s4: designing the type and the dosage of the steel fibers, and determining the proportion of the steel fibers with different specifications;
s5: the amount of the additive is determined.
Further, the particle size interval where the powder system is located is partitioned, and the proportion of various powder materials is determined based on a powder distribution formula; the specific partitioning method is as described above.
Further, the granularity interval where the fine aggregate system is located is partitioned, and the proportion of various fine aggregates is determined based on a fine aggregate distribution formula; the specific partitioning method is as described above.
Further, the proportion of the steel fibers with different specifications is determined by a complex doping principle; the specific method of determining the ratio is as described above.
Further, the dosage of the additive is determined according to the slump expansion degree of the ultra-high performance concrete, the slump expansion degree is ensured to be between 600 and 800mm, and if the slump expansion degree of the ultra-high performance concrete can not meet the requirement by adjusting the additive, the water consumption and the mass ratio of the powder material to the fine aggregate need to be redesigned, or the additive needs to be replaced.
The specific steps of the step (2) are as follows:
p1: adding the steel fiber with the length-diameter ratio not more than 75 and all fine aggregate into a stirrer, and stirring for 0.5-2 min;
p2: adding all powder materials into a stirrer, and stirring for 0.5-2 min;
p3: adding the additive and water into a stirrer and stirring until the mixture has fluidity; the rotating speed of the stirrer is not lower than 40 revolutions per minute;
p4: keeping the stirring state of the stirrer, and uniformly adding the steel fibers with the length-diameter ratio larger than 75 into the stirrer;
p5: continuously stirring for 300-600 seconds to uniformly mix the mixture;
if the length-diameter ratio of the selected steel fibers is not more than 75, the step P4 is not needed in the preparation of the ultra-high performance concrete; if the aspect ratio of the steel fibers is greater than 75, the steel fibers are all added in step P4.
Compared with the existing ultrahigh-performance concrete and the preparation technology, the invention optimally designs the powder material and the aggregate composition based on the proposed powder distribution formula and the aggregate distribution formula respectively, and obviously improves the working performance of the ultrahigh-performance concrete. Meanwhile, the proportion of steel fibers with different specifications is optimally designed based on the proposed fiber complex doping principle, and the mechanical property of the ultra-high performance concrete is obviously improved. According to the theory, the mixing proportion of the ultra-high performance concrete can be designed efficiently and scientifically, the prepared ultra-high performance concrete can reach the strength grade of C200 through normal temperature curing, the slump expansion degree can reach 700mm, and the ultra-high performance concrete is particularly suitable for C200 concrete construction engineering requiring on-site pouring and normal temperature curing. The ultrahigh-performance concrete and the preparation method thereof provided by the invention give consideration to the mechanical property and the working property of the C200-grade ultrahigh-performance concrete, remove a plurality of inconveniences in the steam curing process, provide theoretical guidance and technical support for the large-scale on-site pouring of the normal-temperature cured C200-strength-grade ultrahigh-performance concrete, and have remarkable ecological, economic and social benefits.
Drawings
FIG. 1 is a graph showing the particle size distribution of the powdery material and the aggregate in examples 1 to 5 and comparative examples 1 to 4.
Detailed Description
The present invention will be described in further detail below with reference to the following detailed description and the accompanying drawings. These examples are not intended to limit the scope of the claims and any methods similar or equivalent to those taught herein are within the scope of the present invention.
FIG. 1 is a graph showing a distribution of particle sizes of a powdery material and an aggregate in examples 1 to 5 and comparative examples 1 to 4.
Example 1
A preparation method of normal temperature curing C200-grade high-fluidity ultrahigh-performance concrete comprises the following steps:
the first step is as follows: determining the raw material mixing ratio; the second step is that: and (3) stirring the raw materials with the determined mixing ratio to prepare the concrete.
And (3) determination of raw material mixing ratio:
the raw material mixing ratio of the normal-temperature curing C200-grade high-fluidity ultrahigh-performance concrete is determined by the following steps:
(1) Determining the mass ratio of different types of powder in the ultra-high performance concrete;
(2) Determining the mass ratio of different kinds of aggregates in the ultrahigh-performance concrete;
(3) Designing the mass ratio of water to the powder material and the mass ratio of the powder material to the aggregate;
(4) Designing the type and the dosage of the steel fibers, and determining the proportion of the steel fibers with different specifications;
(5) The amount of the additive is determined.
The powder material is prepared from PII 52.5R cement (cement), mineral powder and silica fume to form a cement-mineral powder-silica fume ternary system. The median diameter D of the cement, the mineral powder and the silica fume is known by testing the particle size distribution of the three types of powder 50 Respectively 15.17 μm,8.82 μm and 0.26 μm, and the particle size interval of the powder system is determined to be [0 μm,67.52 μm ]]. Because the silica fume and the mineral powder have no overlapping area in the granularity interval, the granularity interval is divided into [0 mu m,1.51 mu m ] by taking the minimum particle size value of 1.51 mu m of the mineral powder as a critical value]And [1.51 μm,67.52 μm]Two subintervals. Because the granularity intervals of the mineral powder and the cement have an overlapping area, the median diameter of the mineral powder is 8.82 mu m as a critical value, and the subintervals of 1.51 mu m and 67.52 mu m]Further divided into [1.51 μm,8.82 μm]And [8.82 μm,67.52 μm]Two subintervals. At this point, the particle size interval of the powder material is [0 μm,67.52 μm ]]Is divided into [0 μm,1.51 μm]、[1.51μm,8.82μm]And [8.82 μm,67.52 μm]And calculating theoretical values of the volume contents of the powder in the three subintervals to be 11.5%, 28.2% and 60.3% in sequence by adopting a powder distribution formula. By adjusting the volume fractions of cement, mineral powder and silica fume, it was found that the subintervals [0 μm,1.51 μm ] were at 64.2%, 25.5% and 10.3%, respectively (as determined by regression analysis or the like), when the volume fractions of cement, mineral powder and silica fume were 64.2%, 25.5% and 10.3%, respectively]、[1.51μm,8.82μm]And [8.82 μm,67.52 μm]The volume of the medium powder is 10.5 percent, 27.3 percent and 59.2 percent respectively, and the square sum of the difference between the theoretical value and the design value of the powder volume in each subinterval is the minimum. The apparent densities of the cement, the mineral powder and the silica fume which are respectively 3.14g/cm are obtained according to the test of the national standard GB/T208-2014 3 、2.80g/cm 3 And 2.20g/cm 3 At this time, the mass fractions of the cement, the mineral powder and the silica fume are 68.2%, 24.2% and 7.6%, and the mass ratio is 1.00.
The aggregate is quartz sand with two specifications of 26-40 meshes (I) and 40-70 meshes (II) to form a quartz sand I-quartz sand II aggregate system. By testing the particle size distribution of the two types of powder, the median diameters of the quartz sand I and the quartz sand II are 592.4 μm and 394.2 μm respectively, and the particle size intervals of the aggregate system are determined to be [229.1 μm,1019.5 μm]. Because the granularity intervals of the two aggregates have an overlapping area, the aggregates are made of quartz sandII, the median diameter of 394.2 μm is critical value, and the particle size interval [229.1 μm,1019.5 μm ] of the aggregate is]Is divided into [229.1 μm,394.2 μm]And [394.2 μm,1019.5 μm]Two subintervals. Theoretical values of the volume contents of the particles in the two subintervals are calculated to be 14.8 percent and 37.8 percent in turn by adopting an aggregate distribution formula. By adjusting the volume fractions of the silica sand I and the silica sand II, it was found that when the volume fractions of the silica sand I and the silica sand II were 39.4% and 13.2%, respectively, the subintervals [229.1 μm,394.2 μm ] were]And [394.2 μm,1019.5 μm]The volume of the medium fine aggregate is 11.6 percent and 34.9 percent respectively, and the square sum of the difference between the theoretical value and the design value of the particle volume in each subinterval is the minimum. The apparent densities of the two quartz sands which are obtained by testing according to the national standard GB/T14684-2019 are both 2.65g/cm 3 At this time, the mass ratio of the quartz sand I to the quartz sand II was 1.
The mass ratio of water to the powder material was designed to be 0.15, and the mass ratio of the powder material to the aggregate was designed to be 1.67.
The fiber is S and M type steel fiber microfilaments with the diameter of 0.2mm and the length-diameter ratio of 30 and 75 respectively, the volume ratio of the M type steel fiber to the S type steel fiber is 0.5.
The additive is a Ls-pc (A) type polycarboxylic acid high-performance water reducing agent produced by Guangdong Ruian scientific and technical practical company Limited, and the mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material.
The normal-temperature curing C200-grade high-fluidity ultrahigh-performance concrete is prepared by mixing the following raw materials in proportion:
(1) Adding the S and M type steel fibers and the aggregates (quartz sand I and quartz sand II) into a stirrer, and stirring for 60 seconds;
(2) Adding the powder materials (cement, mineral powder and silica fume) into a stirrer, and continuously stirring for 60 seconds;
(3) Adding all the polycarboxylic acid high-performance water reducing agent and water into a stirrer to be stirred until the mixture has fluidity;
(4) And continuously stirring for 450 seconds to obtain the normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete.
In this example, the slump expansion of the ultra-high performance concrete was 685mm, the compressive strengths of standard curing at 28d and 90d were 191.7MPa and 201.0MPa, respectively, and the compressive strength of steam curing at 90 ℃ for 2d was 203.4MPa. The concrete with the ultra-high performance in the embodiment has good working performance, meets the requirements of C200 grade concrete with the ultra-high performance under the conditions of standard curing and steam curing, and has excellent mechanical properties.
Example 2
The normal temperature curing C200 grade high fluidity ultra-high performance concrete in this example has the same technical characteristics as example 1 except for the following technical characteristics.
The powder material selects PII 52.5R cement (cement for short), quartz powder and silica fume to form a cement-quartz powder-silica fume ternary system with the particle size ranges of 15.17 mu m,8.82 mu m and 0.26 mu m, and the particle size range of the powder system is [0 mu m,67.52 mu m]. Since there is no overlapping area between the silica fume and the quartz powder, the particle size interval is divided into 0 μm and 1.73 μm]And [1.73 μm,67.52 μm]Two subintervals. Because of the overlapping area of the granularity interval of the quartz powder and the cement, the subinterval is 1.73 mu m and 67.52 mu m]Further divided into [1.73 μm,8.82 μm]And [8.82 μm,67.52 μm]Two subintervals. The theoretical values of the powder volume contents in the three subintervals are sequentially 13.1%, 26.7% and 60.2% by adopting a powder distribution formula, and the sum of squares of the differences between the theoretical values of the powder volume contents in the subintervals and the design value is the minimum when the volume fractions of the cement, the quartz powder and the silica fume are respectively 64.8%, 23.3% and 12.0% by adjusting the volume fractions of the cement, the quartz powder and the silica fume. The apparent densities of the cement, the quartz powder and the silica fume which are obtained by testing according to the national standard GB/T208-2014 are respectively 3.14g/cm 3 、2.65g/cm 3 And 2.20g/cm 3 At this time, the mass fractions of the cement, the quartz powder and the silica fume were 69.8%, 21.1% and 9.1%, and the mass ratio was 1.00.
The aggregate is quartz sand with two specifications of 26-40 meshes (I) and 40-70 meshes (II) to form a quartz sand I-quartz sand II aggregate system. The mass ratio of the quartz sand I to the quartz sand II in the aggregate system is 1.33, and the calculation process is the same as that in example 1.
The mass ratio of water to the powder material was designed to be 0.145, and the mass ratio of the powder material to the aggregate was designed to be 2.0.
The kind, amount and blending ratio of the fiber were the same as those of example 1.
The additive is a Ls-pc (A) type polycarboxylic acid high-performance water reducing agent produced by Guangdong Ruian scientific and technical practical company Limited, and the mixing amount of the water reducing agent is 4.0 percent of the mass of the powder material.
In this example, the slump expansion of the ultra-high performance concrete was 655mm, the compressive strengths of standard curing at 28d and 90d were 193.2MPa and 207.3MPa, respectively, and the compressive strength of steam curing at 90 ℃ at 2d was 204.4MPa. The concrete with the ultra-high performance in the embodiment has good working performance, meets the requirements of C200 grade concrete with the ultra-high performance under the standard curing condition, and has excellent mechanical properties.
Example 3
The normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete in this example has the same technical characteristics as example 1 except for the following technical characteristics.
The powder material is a cement-mineral powder-silica fume ternary system, the mass ratio of PII 52.5R cement, mineral powder and silica fume in the system is 1.00.
The aggregate is quartz sand with three specifications of 26-40 meshes (I), 40-70 meshes (II) and 70-120 meshes (III) to form a quartz sand I-II-III system, the median diameters of the quartz sand I, II and III are 592.4 mu m,394.2 mu m and 229.1 mu m respectively, and the granularity interval of the aggregate system is [152.45 mu m,1019.50 mu m]. Because the granularity intervals of the quartz sand I-II and the quartz sand II-III are both overlapped, the granularity interval (152.45 mu m,1019.50 mu m) where the aggregate is positioned is divided into]Is divided into [152.45 μm,229.1 μm]、[229.1μm,394.2μm]And [394.2 μm,1019.5 μm]Three subintervals. The volume contents of the particles in the three subintervals are sequentially 8.7 percent, 14.8 percent and 37.8 percent by adopting an aggregate distribution formula, and the sum of squares of the differences between the theoretical values and the design values of the volumes of the particles in the three subintervals is the minimum when the volume (mass) fractions of the quartz sands I, II and III are respectively 44.1 percent, 6.2 percent and 11.1 percent by adjusting the volume fractions of the three quartz sands. The apparent densities of the two quartz sands which are obtained by testing according to the national standard GB/T14684-2019 are both 2.65g/cm 3 And the mass ratio of the quartz sand I, II and III is 1.
The mass ratio of water to the powder material was designed to be 0.155, and the mass ratio of the powder material to the aggregate was designed to be 1.5.
The kind, amount and blending ratio of the fibers were the same as those of example 1.
The additive is a Ls-pc (A) type polycarboxylic acid high-performance water reducing agent produced by Guangdong Ruian scientific and technical industries, and the mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material.
In this example, the slump expansion of the ultra-high performance concrete was 705mm, the compressive strengths at standard curing of 28d and 90d were 187.4MPa and 200.5MPa, respectively, and the compressive strength at 90 ℃ and 2d by steam curing was 201.8MPa. The concrete with the ultra-high performance in the embodiment has good working performance, meets the requirements of C200 grade concrete with the ultra-high performance under the standard curing condition, and has excellent mechanical properties.
Example 4
The normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete in this example has the same technical characteristics as example 1 except for the following technical characteristics.
The powder material is a cement-mineral powder-silica fume ternary system, the mass ratio of PII 52.5R cement, mineral powder and silica fume in the system is 1.00.
The aggregate is quartz sand with two specifications of 26-40 meshes (I) and 40-70 meshes (II) to form a quartz sand I-quartz sand II aggregate system, the mass ratio of the quartz sand I to the quartz sand II in the aggregate system is 1.33, and the calculation process is the same as that in example 1.
The mass ratio of water to the powder material was designed to be 0.16, and the mass ratio of the powder material to the aggregate was designed to be 2.0.
The fiber is M and L type steel fiber microfilaments with the diameter of 0.2mm and the length-diameter ratio of 75 and 100 respectively, the volume (mass) ratio of the L and M type steel fibers is 0.33.
The additive is a Ls-pc (A) type polycarboxylic acid high-performance water reducing agent produced by Guangdong Ruian scientific and technical practical company Limited, and the mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material.
The normal-temperature curing C200-grade high-fluidity ultrahigh-performance concrete is prepared by mixing the following raw materials in proportion:
(1) Adding the M-shaped steel fiber and the aggregates (quartz sand I and quartz sand II) into a stirrer, and stirring for 60 seconds;
(2) Adding the powder materials (cement, mineral powder and silica fume) into a stirrer, and continuously stirring for 60 seconds;
(3) Adding all the additives and water into a stirrer for stirring until the mixture has fluidity;
(4) Uniformly adding the L-shaped steel fibers into a stirrer while stirring by adopting fiber feeding equipment (a fiber distributing machine, a fiber distributing bin and the like);
(5) And continuously stirring for 500 seconds to obtain the normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete.
In this example, the slump expansion of the ultra-high performance concrete was 620mm, the compressive strengths at 28d and 90d in the standard curing were 185.9MPa and 201.5MPa, respectively, and the compressive strength at 90 ℃ in the steam curing for 2d was 203.6MPa. The result shows that the ultra-high performance concrete in the embodiment has good working performance, meets the requirements of C200 grade ultra-high performance concrete under standard curing conditions, and has excellent mechanical properties.
Example 5
The normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete in this example has the same technical characteristics as example 1 except for the following technical characteristics.
The powder material is a cement-mineral powder-silica fume ternary system, the mass ratio of PII 52.5R cement, mineral powder and silica fume in the system is 1.00.
The aggregate is quartz sand with two specifications of 26-40 meshes (I) and 40-70 meshes (II) to form a quartz sand I-quartz sand II aggregate system, the mass ratio of the quartz sand I to the quartz sand II in the aggregate system is 1.33, and the calculation process is the same as that in example 1.
The mass ratio of water to the powder material was designed to be 0.16, and the mass ratio of the powder material to the aggregate was designed to be 1.82.
SS type steel fiber microfilaments and LL type steel fiber microfilaments with the diameter of 0.12mm and the length-diameter ratio of 50 to 100 are selected as the fibers, the volume ratio of the LL type steel fiber to the SS type steel fiber is 0.25 to 1, and the total mixing amount of the steel fibers is 4.0 percent of the volume of the ultrahigh-performance concrete.
The additive is a Ls-pc (A) type polycarboxylic acid high-performance water reducing agent produced by Guangdong Ruian scientific and technical practical company Limited, and the mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material.
The normal-temperature curing C200-grade high-fluidity ultrahigh-performance concrete is prepared by mixing the following raw materials in proportion:
(1) Adding SS type steel fibers and aggregates into a stirrer, and stirring for 60 seconds;
(2) Adding the powder material into a stirrer, and continuously stirring for 60 seconds;
(3) Adding all the additives and water into a stirrer for stirring until the mixture has fluidity;
(4) Uniformly adding LL-type steel fibers into a stirrer while stirring by adopting fiber feeding equipment;
(5) And continuously stirring for 600 seconds to obtain the normal-temperature cured C200-grade high-fluidity ultra-high-performance concrete.
The super high performance concrete slump expansion of the embodiment is 635mm, the standard curing 28d and 90d compressive strengths are 188.2MPa and 201.6MPa respectively, and the steam curing 2d compressive strength at 90 ℃ is 203.1MPa. The concrete with the ultra-high performance in the embodiment has good working performance, meets the requirements of C200 grade concrete with the ultra-high performance under the standard curing condition, and has excellent mechanical properties.
The physicochemical properties of the ultra-high performance concrete raw materials described in the following comparative examples were the same as those of the examples.
Comparative example 1
The powder material is selected from cement, mineral powder and silica fume, and the mass ratio of the cement to the mineral powder to the silica fume is 1.00. The aggregate is quartz sand with two specifications of 26-40 meshes (I) and 40-70 meshes (II), and the proportion of the two is 1.00. The mass ratio of the powder material to the aggregate was 1.67, and the mass ratio of water to the powder material was 0.15. The fibers are S and M type steel fiber microfilaments with the diameter of 0.2mm and the length-diameter ratio of 30 and 75 respectively, and the volume mixing amount of the S and M type steel fiber microfilaments is 3.0 percent and 1.5 percent respectively. The mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material, and the mixing process of the ultra-high performance concrete is the same as that of the embodiment 1. The present comparative example did not carry out the ratio determination according to the ratio determination method of the present invention.
The comparative example has an ultra-high performance slump expansion of 520mm, standard curing compressive strengths of 168.8MPa and 177.8MPa for 28d and 90d respectively, and steam curing compressive strength of 181.3MPa for 2d at 90 ℃. The working performance of the ultra-high performance concrete in the embodiment is poor, and the compressive strength of the ultra-high performance concrete in the embodiment does not meet the requirement of C200 grade ultra-high performance concrete under the standard curing and steam curing conditions.
Comparative example 2
The powder material is selected from cement, mineral powder and silica fume, and the mass ratio of the cement to the mineral powder to the silica fume is 1.00. The aggregate is quartz sand with two specifications of 26-40 meshes (I) and 40-70 meshes (II), and the proportion of the two is 1. The mass ratio of the powder material to the aggregate was 1.5, and the mass ratio of water to the powder material was 0.15. The fibers are S and M type steel fiber microfilaments with the diameter of 0.2mm and the length-diameter ratio of 30 and 75 respectively, and the volume mixing amount of the S and M type steel fiber microfilaments is 3.0 percent and 1.5 percent respectively. The mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material, and the mixing process of the ultra-high performance concrete is the same as that of the example 1. The present comparative example was not matched according to the matching method of the present invention.
In this example, the slump expansion of the ultra-high performance concrete was 580mm, the compressive strengths of standard curing at 28d and 90d were 172.4MPa and 181.1MPa, respectively, and the compressive strength of steam curing at 90 ℃ at 2d was 183.8MPa. The working performance of the ultra-high performance concrete in the embodiment is poor, and the compressive strength of the ultra-high performance concrete in the embodiment does not meet the requirement of C200 grade ultra-high performance concrete under the standard curing and steam curing conditions.
Comparative example 3
The powder material is selected from cement, quartz powder and silica fume, and the mass ratio of the cement to the quartz powder to the silica fume is 1.00. The aggregate is quartz sand with three specifications of 26-40 meshes (I), 40-70 meshes (II) and 70-120 meshes (III), and the proportion of the three is 1. The mass ratio of the powder material to the aggregate was 1.5, and the mass ratio of water to the powder material was 0.15. The fibers are S and M type steel fiber microfilaments with the diameter of 0.2mm and the length-diameter ratio of 30 and 75 respectively, and the volume mixing amount of the S and M type steel fiber microfilaments is 3.0 percent and 1.5 percent respectively. The mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material, and the mixing process of the ultra-high performance concrete is the same as that of the embodiment 1. The present comparative example was not matched according to the matching method of the present invention.
In this example, the slump expansion of the ultra-high performance concrete is 545mm, the compressive strengths of standard curing at 28d and 90d are 178.3MPa and 187.9, respectively, and the compressive strength of steam curing at 90 ℃ at 2d is 190.5MPa. The working performance of the ultra-high performance concrete in the embodiment is poor, and the compressive strength of the ultra-high performance concrete in the embodiment does not meet the requirement of C200 grade ultra-high performance concrete under the standard curing and steam curing conditions.
Comparative example 4
The powder material is selected from cement, mineral powder and silica fume, and the mass ratio of the cement to the mineral powder to the silica fume is 1.00. The aggregate is quartz sand with two specifications of 26-40 meshes (I) and 40-70 meshes (II), and the proportion of the two is 1. The mass ratio of the powder material to the aggregate was 1.67, and the mass ratio of water to the powder material was 0.15. The fiber is S and M type steel fiber microfilaments with the diameter of 0.2mm and the length-diameter ratio of 30 and 75 respectively, and the volume mixing amount of the S and M type steel fiber microfilaments is 1.5 percent and 3.0 percent respectively. The mixing amount of the water reducing agent is 3.5 percent of the mass of the powder material, and the mixing process of the ultra-high performance concrete is the same as that of the example 1. The present comparative example was not matched according to the matching method of the present invention.
In the embodiment, the expansion of the ultra-high performance concrete slump is 645mm, the compressive strength of standard curing in 28d and 90d is 182.6MPa and 192.2MPa respectively, and the compressive strength of steam curing in 2d at 90 ℃ is 195.1MPa. The working performance of the ultra-high performance concrete in the embodiment is good, but the compressive strength of the ultra-high performance concrete in the embodiment does not meet the requirement of C200 grade ultra-high performance concrete under the standard curing and steam curing conditions.
The amount of the single raw material used in each mixing ratio was calculated from the mass ratio of the raw materials in examples 1 to 5 (S1 to S5) and comparative examples 1 to 4 (R1 to S4) and the apparent densities of the respective raw materials, and is shown in table 1:
TABLE 1 compounding ratio (kg/m) of examples to comparative examples 3 )
Slump-spread and compressive strength indexes of the ultra-high performance concrete in examples and comparative examples are shown in Table 2.
TABLE 2 ultra high Performance concrete Performance index
Claims (6)
1. The normal-temperature cured C200-grade high-fluidity ultrahigh-performance concrete is characterized in that: the material mainly comprises 800 to 1500 weight parts of powder material, 500 to 1500 weight parts of fine aggregate, 30 to 100 weight parts of external additive, 112 to 240 weight parts of water and 234 to 468 weight parts of steel fiber;
the powder material comprises cement, an auxiliary cementing material and an inert filler;
the median particle size of the particles of the supplementary cementitious material is not greater than the median particle size of the particles of cement;
the median particle size of the particles of the inert filler is not greater than the median particle size of the particles of cement;
the fine aggregate is graded continuous aggregate or single-particle-grade aggregate with various particle sizes;
the particle size of the fine aggregate is not more than 2.5mm;
the mass ratio of the powder material to the fine aggregate is 0.8 to 2;
the additive is a water reducing agent or a mixture of the water reducing agent and more than one of a defoaming agent, an early strength admixture and a retarder;
the mass ratio of the water to the powder material is 0.14 to 0.16;
the steel fiber is a microfilament steel fiber, the diameter of the microfilament steel fiber is 0.1 to 0.3mm, and the length-diameter ratio of the microfilament steel fiber is 30 to 100;
the mass ratio between different kinds of powder is determined by the following method:
the first step is as follows: selecting the type of powder material to form a powder system; testing the particle size distribution of various powder materials;
the second step is that: determining the granularity interval of the powder system;
the third step: dividing the granularity interval in which the powder material is positioned into sub-intervals, and calculating the theoretical value of the volume content of the powder in each sub-interval by adopting a powder distribution formula;
the fourth step: presetting the volume of each powder material, calculating the design value of the powder volume in each subinterval, and selecting the volume content of each powder when the square sum of the difference between the theoretical value and the design value of the powder volume in each subinterval is minimum;
the fifth step: testing the apparent density of various powder materials, and calculating the mass ratio among the various powder materials in the system;
the mass ratio between different types or particle size specifications or graded fine aggregates is determined by the following method:
(1) Selecting fine aggregate types or particle size specifications or grading to form an aggregate system, and testing the particle size distribution of various fine aggregates;
(2) Determining a granularity interval where the fine aggregate is located;
(3) Dividing the granularity interval in which the fine aggregate is positioned into sub-intervals, and calculating the volume content theoretical value of the fine aggregate in each sub-interval by adopting a fine aggregate distribution formula;
(4) Presetting the volume of various fine aggregates, calculating the design value of the fine aggregate volume in each subinterval, and determining the volume content of various fine aggregates when the square sum of the difference between the theoretical value and the design value of the aggregate volume in each subinterval is minimum;
(5) Testing the apparent density of various fine aggregates, and calculating the mass ratio among the various fine aggregates in the system;
for a powder system consisting of X powder materials, wherein X is an integer more than or equal to 2; the granularity interval of the powder system is determined by the following method: the particle diameter value of the x-th powder particle when the cumulative particle size reaches 95% is recorded as the characteristic particle diameter value of the powder x
(ii) a X kinds of powder materials have X characteristic particle size values, and the maximum value of the X characteristic particle size values is recorded as the characteristic particle size of the powder material system, namely
The number of the subintervals is the same as the type of the powder material; the subintervals are determined by:
for a binary system P consisting of two powder materials 1 -P 2 Median diameter of the particles
Is greater than
If there is no overlapping region between the particle size ranges of the two kinds of powders, the powder P is used 2 Median minimum particle size value
Is a critical point, adding P 1 -P 2 Particle size interval of the system [2 ]
,
]Division into subintervals I: [
,
]And sub-interval II: [
,
](ii) a If P 1 -P 2 The powder P is used when there is an overlapping region between the two powder particle size ranges 1 Middle diameter of
The critical point is the particle size interval of the powder
,
]Divided into two subintervals
,
]And 2
,
]；
For ternary system P formed by three powder materials 1 -P 2 -P 3 ，P 1 、P 2 、P 3 The median diameter of the granules increases gradually, and is firstly regarded as P 1 -P 2-3 A binary-like system, in which case P is 2 And P 3 Viewed as a mixed particle System P 2-3 ，P 2-3 The particle system is in the particle size interval of [2 ]
,
](ii) a According to the powder P 1 And mixed powder P 2-3 Whether the granularity interval has an overlapping area or not is judged, and P is divided according to an interval division method of a binary system 1 -P 2-3 The system granularity interval is divided into a subinterval I and a subinterval II; within interval II, according to P 2 、P 3 Whether the granularity intervals of the two powder materials are overlapped or not is judged, and the interval II is further divided into subintervals II 1 And sub-interval II 2 I.e. P 1 -P 2 -P 3 The system granularity interval is finally divided into I, II 1 And II 2 Three subintervals;
for the quaternary and the above systems formed by four or more powder materials, the subinterval division method is analogized with a binary system and a ternary system;
the powder distribution formula is
When the powder material system is the firstiThe sub-region is [2 ]i 1 , i 2 ]The theoretical value of the powder volume content in this sub-interval is
(ii) a Then calculating theoretical values of the volume content of the fine aggregate in each divided subinterval;
in the fourth step, the design value of the powder volume in each subinterval is determined by the following method: setting the volume sum of X powder materials as 100% for a powder system consisting of X powder materials; the powder system has X sub-intervals, and after the volume content of various powder materials is set, the X powder material is in the secondiSub zone [2 ]i 1 , i 2 ]In volume fraction of
Wherein
Is a set value of the volume content of the x-th powder material,
the particle size distribution curve of the x type powder is in the interval [2 ]i 1 , i 2 ]The volume ratio of the powder contained in the powder; all X kinds of powder material are in the sub-intervaliThe sum of the volumes in (A) is
Will be a sub-intervaliThe design value of the powder volume is recorded as
(ii) a The calculation method of the volume design values of the powder in other subintervals is the same as the above;
in the fourth step, the volume content of each type of powder is determined by the following steps: for a powder system containing X subintervals, firstly, calculating a theoretical value of the volume content of the powder in each subinterval
(ii) a Secondly, presetting the volume content of various powder materials, wherein the sum of the volumes of the various powder materials is 100%, and calculating the design value of the volume of powder in each subinterval
(ii) a Then, adjusting the set value of the volume content of each powder material to enable the theoretical value of the volume of the powder in each subinterval
And design value
Sum of squares of the differencesR P At a minimum, wherein
in the method for determining the mass ratio between the fine aggregates,
for an aggregate system consisting of fine aggregates with a Y-type particle size specification, the particle size interval in which the system is located is determined by the following steps: the value of the particle diameter at which the cumulative particle size of the y-th fine aggregate particles reached 10% was regarded as the characteristic particle diameter
The particle diameter at which the cumulative particle size of the particles reaches 95% is referred to as the characteristic particle diameter
(ii) a Characteristic particle size of fine aggregate system
，
(ii) a The granularity interval of the fine aggregate system is marked as [2 ]
,
]；
The method for dividing the fine aggregate subintervals is consistent with the method for dividing the powder material subintervals: the number of the subintervals is the same as the type or granularity specification number of the fine aggregate; the subintervals are determined by:
for a binary system A consisting of two fine aggregates or fine aggregates of two particle size specifications 1 -A 2 Median diameter of the particle
Is greater than
，
Is greater than
(ii) a If the granularity intervals of two fine aggregates or fine aggregates with two granularity specifications are not overlapped, the fine aggregate A is used 2 Median minimum particle diameter value
Is a critical point, A 1 -A 2 Particle size interval of the system [2 ]
,
]Division into subintervals I: [
,
]And sub-interval II: [
,
](ii) a If A 1 -A 2 The fine aggregate A is used when the granularity interval of the two fine aggregates in the system has an overlapping area 1 Middle diameter of
Is a critical point, and the particle size interval of the fine aggregate is set
,
]Divided into two subintervals
,
]And 2
,
]；
For ternary system A formed by three fine aggregates or fine aggregates with three granularity specifications 1 -A 2 -A 3 ，A 1 、A 2 、A 3 Median diameter of the particles
、
、
The number of the grooves is increased in turn,
、
、
in
Minimum; first, it is regarded as A 1 -A 2-3 A system similar to a binary system is provided,at this time, A is 2 And A 3 Viewed as a mixed particle System A 2-3 ，A 2-3 The particle system is in the particle size interval of [2 ]
,
](ii) a According to the fine aggregate A 1 With mixing fine aggregate A 2-3 Whether the granularity interval has an overlapping area or not is judged according to the interval division method of a binary system 1 -A 2-3 The system granularity interval is divided into a subinterval I and a subinterval II; in interval II, according to A 2 、A 3 Whether the granularity intervals of the two fine aggregate are overlapped or not is judged, and the interval II is further divided into subintervals II 1 And sub-interval II 2 That is to say, A 1 -A 2 -A 3 The system granularity interval is finally divided into I, II 1 And II 2 Three subintervals;
for quaternary and above systems formed by four and above granularity specification fine aggregates, the subinterval division method is analogized with a binary system and a ternary system;
the fine aggregate distribution formula is
When in the fine aggregate systemjThe subinterval is [2 ]j 1 , j 2 ]The theoretical value of the volume content of the fine aggregate in the subinterval is
(ii) a Calculating theoretical values of the volume contents of the fine aggregates in all the subintervals;
the design value of the volume of the subinterval fine aggregate is determined by the following method: for an aggregate system consisting of Y kinds of fine aggregates, Y sub-intervals are provided, and when the volume content of each kind of fine aggregates is set, the Y kind of fine aggregates are arranged on the YjSub-section [2 ]j 1 , j 2 ]In volume fraction of
Wherein
Is the set value of the volume content of the y type fine aggregate,
the particle size distribution curve of the y fine aggregate is in the interval [2 ]j 1 , j 2 ]The volume fraction of the aggregate contained therein; all Y fine aggregates are in the subintervaljThe sum of the volumes in (A) is
Will be a sub-intervaljThe design value of the fine aggregate volume is recorded as
(ii) a The calculation method of the volume design values of the fine aggregate in other subintervals is the same as the above; the volume content of various fine aggregates in the step (4) is determined by the following steps: for a fine aggregate system containing Y subintervals, firstly, calculating a theoretical value of the volume content of the fine aggregate in each subinterval
(ii) a Secondly, the volume content of various fine aggregates is preset, so that the sum of the volumes of the various fine aggregates is
the doping amount of the steel fiber is not less than 3% of the volume of the ultra-high performance concrete;
the steel fibers adopt steel fibers with different length-diameter ratios;
when steel fibers with different length-diameter ratios are adopted for complex doping, the proportion of the steel fibers with various specifications meets the complex doping principle: for two aspect ratio specification steel fiber systems F 1 -F 2 ，F 2 Aspect ratio greater than F 1 Steel fiber F 2 And F 1 The volume ratio of (a) is 0.25 to 0.50;
for three aspect ratio specification steel fiber systems F 1 -F 2 -F 3 ，F 1 、F 2 、F 3 The length-diameter ratio is increased in turn, and the steel fiber F 2 And F 1 (iii) a volume ratio of (1) 0.20 to 0.35 3 And F 2 The volume ratio of (b) is 0.20 to 0.35.
2. The ambient curing C200-grade high-fluidity ultrahigh-performance concrete according to claim 1, characterized in that:
the fine aggregate is more than one of quartz sand, corundum sand and river sand;
the cement is Portland cement or ordinary Portland cement;
the auxiliary cementing material is more than one of powdery materials with hydration activity or volcanic ash activity, such as silica fume, mineral powder and fly ash;
the inert filler is more than one of quartz powder and limestone powder;
the water reducing agent is a polycarboxylic acid high-performance water reducing agent.
3. The room-temperature cured C200-grade high-fluidity ultra-high-performance concrete as claimed in claim 2, wherein: the cement is Portland cement or ordinary Portland cement with the strength grade of 52.5;
the fine aggregate is more than one of quartz sand and corundum sand.
4. The method for preparing normal temperature curing C200-grade high-fluidity ultra-high performance concrete according to any one of claims 1~3, which is characterized in that: the method comprises the following steps:
(1) Determining the mixing ratio of each raw material in the ultra-high performance concrete;
(2) Stirring the raw materials;
the mixing proportion of the raw materials in the ultra-high performance concrete in the step (1) is determined by the following method:
s1: determining the mass ratio of different types of powder materials in the ultra-high performance concrete;
s2: determining the mass ratio of fine aggregates of different types or granularity specifications in the ultra-high performance concrete;
s3: designing the water consumption and the mass ratio of the powder material to the fine aggregate;
s4: designing the type and the dosage of the steel fibers, and determining the proportion of the steel fibers with different specifications;
s5: determining the dosage of the additive;
the specific steps of the step (2) are as follows: if the selected steel fibers are steel fibers with the length-diameter ratio not more than 75 and steel fibers with the length-diameter ratio more than 75,
p1: adding the steel fiber with the length-diameter ratio not greater than 75 and all the fine aggregate into a stirrer, and uniformly stirring;
p2: adding all powder materials, and uniformly stirring;
p3: adding an additive and water, and stirring until the mixture has fluidity;
p4: keeping the stirring state, and adding the steel fiber with the length-diameter ratio larger than 75 into a stirrer;
p5: continuously stirring for 300 to 600 seconds to uniformly stir the mixture;
if the length-diameter ratio of the selected steel fibers is not more than 75, the step P4 is omitted; if the aspect ratio of the steel fibers is greater than 75, the steel fibers are all added in step P4.
5. The method for preparing the ambient curing C200-grade high-fluidity ultrahigh-performance concrete according to claim 4, characterized in that:
the mass ratio between different kinds of powder is determined by the following method:
the first step is as follows: selecting the type of powder material to form a powder system; testing the particle size distribution of various powder materials;
the second step is that: determining the granularity interval of the powder system;
the third step: dividing the granularity interval in which the powder material is positioned into sub-intervals, and calculating the theoretical value of the volume content of the powder in each sub-interval by adopting a powder distribution formula;
the fourth step: presetting the volume of each powder material, calculating the design value of the powder volume in each subinterval, and selecting the volume content of each powder when the square sum of the difference between the theoretical value and the design value of the powder volume in each subinterval is minimum;
the fifth step: testing the apparent density of various powder materials, and calculating the mass ratio among the various powder materials in the system;
the mass ratio between different types or particle size specifications or graded fine aggregates is determined by the following method:
(1) Selecting fine aggregate types or particle size specifications or grading to form an aggregate system, and testing the particle size distribution of various fine aggregates;
(2) Determining a granularity interval where the fine aggregate is located;
(3) Dividing the granularity interval in which the fine aggregate is positioned into sub-intervals, and calculating the volume content theoretical value of the fine aggregate in each sub-interval by adopting a fine aggregate distribution formula;
(4) Presetting the volume of various fine aggregates, calculating the design value of the volume of the fine aggregates in each subinterval, and determining the volume content of the various fine aggregates when the square sum of the difference between the theoretical value and the design value of the volume of the aggregates in each subinterval is minimum;
(5) Testing the apparent density of various fine aggregates, and calculating the mass ratio among the various fine aggregates in the system;
when steel fibers with different length-diameter ratios are adopted for complex doping, the proportion of the steel fibers with various specifications meets the complex doping principle: for two aspect ratio specification steel fiber systems F 1 -F 2 ，F 2 Aspect ratio greater than F 1 Steel fiber F 2 And F 1 The volume ratio of (A) to (B) is 0.25 to 0.50;
for three aspect ratio specification steel fiber systems F 1 -F 2 -F 3 ，F 1 、F 2 、F 3 The length-diameter ratio is increased in turn, and the steel fiber F 2 And F 1 (iv) a volume ratio of (1) to (0.20) - (0.35) 3 And F 2 The volume ratio of (a) is 0.20 to 0.35;
the using amount of the additive is determined according to the slump expansion degree of the ultra-high performance concrete, the slump expansion degree is ensured to be 600-800mm, and if the slump expansion degree of the ultra-high performance concrete can not meet the requirement by adjusting the additive, the water consumption and the mass ratio of the powder material to the fine aggregate need to be redesigned, or the additive needs to be replaced.
6. The method for preparing normal temperature curing C200 grade high-fluidity ultra-high performance concrete according to claim 4, characterized by comprising the following steps: the stirring time in the step P1 is 0.5 to 2min; the stirring time in the step P2 is 0.5 to 2min; the rotating speed of stirring in the steps P1-P5 is not less than 40 revolutions per minute.
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