CN114477908A

CN114477908A - Low-carbon ultra-light ultra-high-strength concrete and preparation method thereof

Info

Publication number: CN114477908A
Application number: CN202210153264.5A
Authority: CN
Inventors: 康小朋; 李斌斌; 徐腾飞
Original assignee: Jiangsu Jianhua New Material Technology Co ltd; Jianhua Construction Materials China Co Ltd
Current assignee: Jiangsu Jianhua New Material Technology Co ltd; Jianhua Construction Materials China Co Ltd
Priority date: 2022-02-18
Filing date: 2022-02-18
Publication date: 2022-05-13
Anticipated expiration: 2042-02-18
Also published as: CN114477908B

Abstract

The invention belongs to the technical field of building materials, and discloses low-carbon ultra-light ultra-high-strength concrete and a preparation method thereof. Adding the cement, the multifunctional admixture, the nano material and the shrinkage compensation agent into a stirrer for stirring and uniformly mixing; then adding 60-80% of water and 60-80% of composite additive, uniformly mixing, and then adding seed crystals and stirring; adding fine aggregate, continuously stirring, and adding 10-30% of water and 10-30% of composite additive mixed liquor in the stirring process; adding fibers, continuously stirring, and adding all the remaining water and the composite additive mixed solution in the stirring process; adding the coarse aggregate and stirring; and pouring the obtained product into a mold after vacuumizing, vibrating, and curing after molding to obtain the ultralight and ultrahigh-strength concrete. The concrete obtained by the invention meets the requirement of ultra-low volume weight of 1300-1600 kg/m³Meanwhile, the composite material has ultrahigh strength of 100-120 MPa and excellent durability, and is suitable for building structures with ultrahigh-rise and ultra-large span.

Description

Low-carbon ultra-light ultra-high-strength concrete and preparation method thereof

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to low-carbon ultra-light ultra-high-strength concrete and a preparation method thereof.

Technical Field

The concrete is the most widely applied building material in the engineering construction field, the structural span is continuously increased along with the continuous improvement of the building height, and the common concrete has large self weight, relatively heavy structure, large construction difficulty and high transportation and construction cost, so that the concrete is difficult to meet the requirement of the rapid development of the building industries such as super high-rise buildings, large-span bridges and the like. The lightweight concrete has light dead weight, good heat preservation and earthquake resistance, and has wide application in the special fields of building energy conservation, high-rise buildings, earthquake resistance and the like. However, the lightweight concrete uses a large amount of lightweight aggregates such as ceramsite and ceramic sand to replace high-strength gravel, so that the framework supporting effect of the aggregates is weakened, the volume weight of the concrete is reduced, and the strength of the concrete is also greatly reduced, and due to the limitation of technical bottlenecks, the volume weight of the lightweight concrete in the current engineering application is usually 1600-2000 kg/m3, the compressive strength is less than or equal to 70MPa, and no application case of ultrahigh-strength lightweight concrete (the strength is more than or equal to 100MPa) exists.

The volume weight of the traditional ultra-high performance concrete (the strength is more than or equal to 100MPa) is usually 2600kg/m³Has ultrahigh mechanical property, and the prepared building member can save 24 percent of materials and reduce the cost compared with the traditional reinforced concrete under the same bearing forceLow weight (35%), saving energy (54%), and reducing CO directly discharged₂And global warming GwP (equivalent CO)₂Emissions) reach 59% and 44%, respectively, with excellent durability and service life. How to realize the organic combination of concrete ultra-lightness and ultra-high performance has important research significance.

In the existing literature, relevant scholars further improve the strength of the lightweight concrete on the technical level by combining and matching some superfine powder materials and special fine aggregates, but the volume weight is not obviously improved. CN110922132A patent CN A lightweight ultra-high strength concrete and a preparation method thereof, the lightweight ultra-high strength concrete with the compressive strength of 130MPa is prepared by cement, admixture, broken stone, glass micro-beads, excitant, steel fiber and water reducing agent, but the volume weight of the concrete is 1850kg/m because the density of the broken stone is higher³Left and right. CN111362635B patent CN & lt & ltA light ultra-high strength concrete & gt and preparation method thereof & gt prepares the concrete with the compressive strength of 105-1850 kg/m and the bulk weight of 1850kg/m & lt/A & gt of 124MPa by using cement, ultrafine fly ash, silica fume, carborundum powder, floating beads, Peek plastic particles, organic polymer water-absorbing resin and polycarboxylic acid water reducing agent³The concrete realizes the optimization of the volume weight of the ultra-high strength concrete, but the concrete has higher cement consumption and larger carborundum powder density, and limits the further light weight of the volume weight of the concrete. CN112521095A patent of lightweight high-strength concrete and preparation method thereof, cement, silica fume, fly ash, hollow glass beads, ceramsite, titanium boride particles, polyamide fibers and water reducing agent are used for preparing the lightweight high-strength concrete with the volume weight of 1350kg/m³The strength of the light concrete is only 60MPa, and the light concrete cannot meet the requirement of ultrahigh mechanical property.

Based on summary analysis, because of the technical bottleneck of contradiction between concrete lightness and mechanical property, no existing engineering case and literature data has a volume weight less than or equal to 1600kg/m³The concrete with the strength not less than 100MPa is related to reports, so the development volume weight is 1300-1600 kg/m³The ultra-light and ultra-high-strength concrete material with the strength of 100-120 MPa realizes mutual compatibility of ultra-high performance and ultra-low volume weight of concrete, and meets the requirements of continuously improving the building height and continuously increasing the structural span for further development of the technology of promoting light concreteThe increased demand is of great significance.

Disclosure of Invention

The invention aims to provide low-carbon ultra-light ultra-high-strength concrete and a preparation method thereof, which meet the requirement of ultra-low volume weight (1300-1600 kg/m) of the concrete³) Meanwhile, the light concrete has ultrahigh strength (100-120 MPa) and excellent durability, is suitable for building structures with ultrahigh rise and ultra-large span, and promotes the further development of the light concrete technology.

In order to achieve the purpose, the invention adopts the technical scheme that:

the low-carbon ultra-light ultra-high-strength concrete comprises the following raw materials in parts by weight: 400-450 parts of cement, 300-320 parts of multifunctional admixture, 90-100 parts of nano material, 230-300 parts of fine aggregate, 160-190 parts of coarse aggregate, 15-20 parts of seed crystal, 30-40 parts of fiber, 5-10 parts of shrinkage compensator, 40-50 parts of composite admixture and 110-130 parts of water.

Further, the cement is high belite general portland cement, and the strength grade is more than or equal to 62.5;

further, the multifunctional admixture comprises 50-60 wt% of fly ash-based admixture, 25-30 wt% of superfine mineral powder and 15-20 wt% of silica fume;

further, the fly ash-based admixture is a high-specific-surface-area and high-activity admixture prepared by compounding and grinding I-grade fly ash and alkali metal sulfate, and the specific surface area is more than or equal to 700m²The activity index of the catalyst per kg and 7d is more than or equal to 120;

furthermore, the fineness of the superfine mineral powder is more than or equal to 1000 meshes, and the activity is more than or equal to S120;

further, the purity of the silica fume is more than or equal to 96 percent;

further, the nano material comprises 15-20 wt% of nano silicon dioxide and 80-85 wt% of nano calcium carbonate;

furthermore, the purity of the nano silicon dioxide is more than or equal to 99 percent, and the average particle size is less than or equal to 20 nm;

furthermore, the purity of the nano calcium carbonate is more than or equal to 98 percent, and the average particle size is less than or equal to 50 nm;

further, the fine aggregate comprises 70-80 wt% of hollow glass beads and 20-30 wt% of floating beads;

furthermore, the true density of the hollow glass beads is less than or equal to 600kg/m³The compression density is more than or equal to 4000 psi;

further, the apparent density of the floating bead is less than or equal to 700kg/m³The fineness is more than or equal to 80 meshes;

further, the coarse aggregate is high-strength ceramic microspheres with the particle size of 5-10 mm, and the stacking density is less than or equal to 850kg/m³The cylinder pressure strength is more than or equal to 8 MPa;

further, the seed crystal is a calcium silicate hydrate gel nano composite material, the solid content is more than or equal to 10%, and the particle size is less than or equal to 40 nm;

further, the fibers are synthetic fibers made of polyformaldehyde materials;

further, the shrinkage compensator is one or more of aluminosilicate, sulphoaluminate, calcium salt and magnesium salt;

further, the composite admixture is a high-shrinkage-high-water-reduction-coagulation-promotion integrated comb-shaped structure polycarboxylic ether copolymer compounded cellulose ether viscosity reducer and a silicone defoaming agent, and the mass ratio of the three is 1000:5: 1; the comb-shaped structure polycarboxylate ether copolymer is formed by copolymerization and esterification of an acrylic acid-based polymer, a grafted organic amine salt and a shrinkage-reducing functional small monomer. The polycarboxylate ether copolymer has the functions of a water reducing agent, an early strength agent and a shrinkage compensation agent.

The invention relates to a preparation method of low-carbon ultra-light ultra-high-strength concrete, which mainly comprises the following steps:

(1) weighing the component materials according to a certain proportion for later use;

(2) adding cement, multifunctional admixture, nano material and shrinkage compensation agent into a stirrer, stirring for 30-60 s, and uniformly mixing;

(3) uniformly mixing (60-80)% of water and (60-80)% of composite additive in the step (1), adding the mixture into the powder in the step (2), stirring for 3-4 min, adding all seed crystals, and stirring for 1 min;

(4) adding all fine aggregates into the slurry obtained in the step (3), continuously stirring for 1-2 min, and adding 10-30% of water and 10-30% of composite additive mixed liquor obtained in the step (1) in the stirring process;

(5) adding fibers in the step (4), continuously stirring for 0.5-1 min, and adding all the water and the composite additive mixed solution in the step (1) in the stirring process;

(6) adding the coarse aggregate in the step (5), and stirring for 20-30 s;

(7) vacuumizing the slurry obtained in the step (6) for 5-10 s, pouring the obtained product into a mold, and vibrating;

(8) after forming, standing and maintaining for 6-12 h under the conditions of 20-30 ℃ and more than or equal to 90 RH%, then performing steam maintenance for 24-48 h at 50-90 ℃, and removing the mold, and performing natural maintenance to obtain the low-carbon ultra-light ultra-high strength concrete.

Furthermore, the concrete volume weight of the ultra-light and ultra-high-strength concrete prepared by the invention is 1300-1600 kg/m³The cubic compressive strength is 100-120 MPa, and the characteristics of ultra-light weight and ultra-high strength are achieved.

Has the advantages that:

(1) the weight is reduced. By selecting low-density high-strength high-performance materials for matching and through the synergistic effect of multiple components, the concrete volume weight of 1300-1600 kg/m is realized within the limited influence range of the mechanical property of the concrete³Ultra-lightweight. Filling effect of light microsphere particles: the hollow glass beads are hollow and closed spherical light materials, the size of the hollow glass beads is 15-100 micrometers, and the hollow glass beads have good compression-resistant bearing capacity while being light in weight; the floating beads have thin and hollow walls, high hardness and high strength, and can reduce the viscosity of a concrete matrix and improve the fluidity based on the ball effect of spherical particles. ② the density of the cement is usually 3.1g/cm³The density of the admixture such as the fly ash-based admixture and the silica fume is 2.1-2.3 g/cm³About, the dosage of the admixture is improved based on the optimization of the mixing proportion, and the slurry density can be greatly reduced; high-strength ceramic microspheres are selected as coarse aggregate, the barrel pressure strength is high, the density of the high-strength ceramic microspheres is close to that of the whole slurry, and the high-strength ceramic microspheres have a good framework supporting effect while the integral homogeneity of the concrete is ensured; the performance of the synthetic fiber made of polyformaldehyde material is close to that of the steel fiber, but the density of the synthetic fiber is only the steel fiber1/5, the volume weight is obviously reduced while the excellent mechanical property of the concrete is ensured.

(2) And (4) ultrahigh strength. The ultrahigh strength of the concrete of 100-120 MPa is realized by adopting the multi-component synergistic effect through the combination and compatibility of high-strength materials, the enhancement of a nanotechnology, the tight particle packing and the control of the ultrahigh compactness of the slurry. High-strength material: based on the skeleton supporting effect of the high-strength ceramsite microspheres, high belite portland cement with extremely high mechanical property is selected and compounded with a multifunctional admixture with high activity and high specific surface area, so that the cement hydration is promoted, meanwhile, the excellent micro powder filling effect is realized, the porosity is reduced through chemical reaction, the internal pore structure is optimized, and the defects are reduced; ② nanotechnology enhancement: the super-strong volcanic ash activity and fineness of the nano powder material are utilized to refine the crystal form of a hydration product, improve an interface mechanism and combine a nano calcium silicate hydrate seed crystal, so that the potential barrier generated by C-S-H gel in the hydration process of a cementing material is reduced, the hydration efficiency of cement is greatly improved, the pore structure and the compactness of hard cement slurry are improved, and the strength, the toughness and the durability of the concrete are improved from a microscopic level; material close packing: the closest packing is formed by utilizing different particle diameters of the components in an optimal proportion, on the basis of the framework support of the ceramic microspheres, the packing gaps of micron-sized hollow glass microspheres and floating beads are filled with submicron-sized cement and admixture, and the submicron-sized pores are filled with nano silicon dioxide and nano calcium carbonate, so that the closest packing of slurry particles is realized to the maximum extent; ultrahigh compactness: the composite admixture has ultrahigh water reducing rate, viscosity reducing and shrinkage reducing effects, realizes the preparation of concrete with low water-to-gel ratio, and simultaneously ensures that the compactness of fresh slurry and hardened slurry cannot leave pore influence strength due to residual water evaporation by combining the vacuumizing treatment in the concrete preparation process, thereby realizing the absolute compactness of concrete.

(3) Excellent durability. The concrete prepared by the invention has very high compactness after hardening, and has excellent durability such as impermeability, carbonization resistance, chloride ion corrosion resistance and the like. Meanwhile, based on the supporting function of coarse and fine aggregates, the constraint function of fibers and the high shrinkage reduction of the composite admixture, the influence of drying shrinkage and chemical shrinkage is remarkably reduced by combining the rapid development of the system strength of the cementing material and steam curing optimization, and the excellent shrinkage resistance of concrete is realized.

(4) Green and low carbon. The concrete prepared by the invention has ultra-light weight and ultra-high strength, and compared with the traditional reinforced concrete, the concrete can further reduce the weight by 40-50% under the same bearing force on the basis of keeping the original weight reduction of the ultra-high performance concrete by 24%, weight reduction by 35% and energy saving by 54%, thereby greatly reducing the material consumption. The prestressed reinforcement is used in upper structures such as bridges, bridge span can be effectively increased, the number of piers is reduced, and the amount of prestressed reinforcements of the upper structures is reduced; when the building block is used in urban buildings, the dead weight of the buildings can be effectively reduced, and the foundation treatment consumption is reduced; meanwhile, the transportation efficiency and the construction efficiency can be obviously improved in the construction process, the environmental load is reduced, and the resource saving effect is obvious.

Detailed Description

The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.

Example 1:

the cement is general portland cement with strength grade of 62.5, and the specific properties are shown in Table 1

TABLE 1 Cement Properties

The fly ash-based admixture is a high-activity admixture prepared from fly ash, sulfate, silicate and the like by an ultrafine grinding technology, and the specific properties are shown in table 2:

TABLE 2 fly ash based admixtures Properties

The specific properties of the superfine mineral powder are shown in Table 3, wherein S140 mineral powder is adopted as the superfine mineral powder:

TABLE 3 superfine Ore powder Properties

Fineness of fineness	Density/(g/cm)³)	Activity of
			2000 mesh	2.86	S140

The specific properties of the silica fume are shown in Table 4:

TABLE 4 silica fume Properties

Purity/%)	Specific surface area/(m)²/kg)	Density/(g/cm)³)	Water demand ratio/%)
				96	2.8×10⁴	2.15	110

The coarse aggregate adopts high-temperature sintered ceramic balls, and the specific properties are shown in table 5:

TABLE 5 coarse aggregate Properties

Particle size/mm	Barrel pressure strength/MPa	Bulk density/(kg/m)³)	Apparent density/(kg/m)³)
				5～10	8～9	600～700	1300～1400

The specific properties of the hollow glass microspheres are shown in Table 6:

TABLE 6 hollow glass Microbead Properties

Compressive density/Psi	True density/(g/cm)³)	Bulk density/(g/cm)³)	Particle size/um	Softening point	pH value	Water content%
							4000	0.4	0.24	85	620	8.0-9.0	≤0.3

The floating beads have the fineness of 80-120 meshes and the apparent density of 720kg/m³

The nano silicon dioxide adopts a hydrophilic product, and the specific properties are shown in the table 7:

TABLE 7 nanosilica Properties

Average particle diameter/nm	Purity/%)	Specific surface area/(m)²/kg)	Density/(g/cm)³)
				20	≥99.6	280	2.31

The specific properties of the nano activated calcium carbonate are shown in Table 8:

TABLE 8 Nano-active calcium carbonate Properties

Average particle diameter/nm	Purity/%)	Fineness (325 mesh) screen residue	Density/(g/cm)³)
				50	≥98.5	0.03	2.73

The specific properties of the calcium silicate hydrate gel seed crystal are shown in Table 9:

TABLE 9 seed Properties

The composite admixture adopts the comb-shaped structure polycarboxylate ether copolymer to compound the viscosity reducer and the defoaming agent, the mass ratio is (1000:5:1), and the specific properties are shown in Table 10:

TABLE 10 Compound additive Properties

The synthetic fiber is POM type reinforced fiber.

Firstly, weighing 400 parts of cement, 160 parts of fly ash-based admixture, 80 parts of ultrafine mineral powder, 64 parts of silica fume, 16 parts of nano-silica, 80 parts of nano-calcium carbonate, 160 parts of ceramic particles, 170 parts of hollow glass microspheres, 60 parts of floating beads, 16 parts of seed crystals, 5 parts of shrinkage compensator, 30 parts of fibers, 120 parts of water and 40 parts of composite additive according to the weight ratio.

Adding cement, fly ash-based admixture, superfine mineral powder, silica fume, nano-silica, nano-calcium carbonate and shrinkage compensator into a stirrer, and stirring for 60s to obtain a mixed powder material; mixing 84 parts of water and 28 parts of additive, stirring uniformly, adding the mixture into the glue powder, stirring for 3min, adding seed crystal, and stirring for 1min to obtain a slurry material; adding hollow glass beads and floating beads, adding a mixed solution of 24 parts of water and 8 parts of additive while stirring, and stirring for 2 min; adding POM synthetic fiber, continuously stirring for 1min, and simultaneously adding all the remaining water and additive mixed liquor in the stirring process; adding ceramic microspheres, stirring for 30s, then vacuumizing for 10s, pouring, vibrating for forming, covering a curing film, standing and curing for 12h under the conditions of 20 ℃ and 95 RH%, performing steam curing at 50 ℃ for 48h, demolding, and naturally curing for 28d to obtain the ultra-light and ultra-high strength concrete.

Example 2:

the cement is general portland cement with strength grade of 62.5, and the specific properties are shown in Table 11

TABLE 11 Cement Properties

The fly ash-based admixture is a high-activity admixture prepared from fly ash, sulfate, silicate and the like by an ultrafine grinding technology, and the specific properties are shown in table 12:

TABLE 12 fly ash based admixtures Properties

The specific properties of the ultrafine mineral powder S140 are shown in Table 13:

TABLE 13 superfine mineral powder Properties

Fineness of fineness	Density/(g/cm)³)	Activity of
			2000 mesh	2.86	S140

The specific properties of the silica fume are shown in Table 4:

TABLE 14 silica fume Properties

The specific properties of the coarse aggregate high-temperature sintered ceramic ball are shown in Table 5:

TABLE 15 coarse aggregate Properties

Particle size/mm	Barrel pressure strength/MPa	Bulk density/(kg/m)³)	Apparent density/(kg/m)³)
				5-～10	10～11	700～800	1400～1500

The specific properties of the hollow glass microspheres are shown in Table 16:

TABLE 16 hollow glass bead Properties

Compressive density/Psi	True density/(g/cm)³)	Bulk density/(g/cm)³)	Particle size/um	Softening point	pH value	Water content%
							6000	0.46	0.39	80	620	8.0-9.0	≤0.3

The specific properties of the nano-silica hydrophilic product are shown in Table 17:

TABLE 17 nanosilica Properties

The specific properties of the nano activated calcium carbonate are shown in table 18:

TABLE 18 nanometer activated calcium carbonate Properties

The specific properties of the calcium silicate hydrate seeds are shown in table 19:

TABLE 19 seed Properties

The composite admixture adopts the comb-shaped structure polycarboxylate ether copolymer to compound the viscosity reducer and the defoaming agent, the mass ratio is (1000:5:1), and the specific properties are shown in Table 20:

TABLE 20 composite additive Properties

The synthetic fiber is POM type reinforced fiber.

Firstly, weighing 420 parts of cement, 150 parts of fly ash-based admixture, 90 parts of superfine mineral powder, 60 parts of silica fume, 16 parts of nano-silica, 80 parts of nano-calcium carbonate, 170 parts of ceramsite particles, 200 parts of hollow glass beads, 60 parts of floating beads, 16 parts of seed crystals, 8 parts of shrinkage compensator, 40 parts of fibers, 110 parts of water and 45 parts of composite admixture according to the weight ratio.

Adding cement, fly ash-based admixture, superfine mineral powder, silica fume, nano-silica, nano-calcium carbonate and shrinkage compensator into a stirrer, and stirring for 45s to obtain a mixed powder material; mixing 88 parts of water and 36 parts of additive, stirring uniformly, adding the mixture into the glue powder, stirring for 3min, adding seed crystal, and stirring for 1min to obtain a slurry material; adding hollow glass beads and floating beads, adding a mixed solution of 11 parts of water and 5 parts of an additive while stirring, and stirring for 2 min; adding POM synthetic fiber, continuously stirring for 0.5min, and simultaneously adding the rest of the mixed solution of water and the additive in the stirring process; adding ceramic microspheres, stirring for 20s, vacuumizing for 8s, pouring, vibration molding, covering a curing film, standing and curing for 12h at 20 ℃ and 95 RH%, curing for 24h with 80 ℃ and normal pressure steam, demolding, and naturally curing for 28d to obtain the ultra-light and ultra-high strength concrete.

Example 3:

the cement is general portland cement with strength grade of 62.5, and the specific properties are shown in Table 21

TABLE 21 Cement Properties

The fly ash-based admixture is a high-activity admixture prepared by fly ash, sulfate, silicate and the like through an ultrafine grinding technology, and the specific properties are shown in Table 22:

TABLE 22 fly ash-based admixtures Properties

The specific performance of the superfine mineral powder is shown in table 23, wherein S140 mineral powder is adopted as the superfine mineral powder:

TABLE 23 properties of the ultrafine ore powders

Fineness of fineness	Density/(g/cm)³)	Activity of
			2000 mesh	2.86	S140

The silica fume adopts high-purity silica fume, and the specific properties are shown in Table 24:

TABLE 24 silica fume Properties

The coarse aggregate adopts high-temperature sintered ceramic balls, and the specific properties are shown in table 25:

TABLE 25 coarse aggregate Properties

Particle size/mm	Barrel crush strength/MPa	Bulk density/(kg/m)³)	Apparent density/(kg/m)³)
				5～10	11.7	820	1585

The specific properties of the hollow glass microspheres are shown in table 26:

TABLE 26 hollow glass bead Performance

Compressive density/Psi	True density-(g/cm³)	Bulk density/(g/cm)³)	Particle size/um	Softening point	pH value	Water content%
							12000	0.6	0.39	70	620	8.0-9.0	≤0.3

The nano silicon dioxide adopts a hydrophilic product, and the specific properties are shown in table 27:

TABLE 27 nanosilica Properties

The specific properties of the nano activated calcium carbonate are shown in Table 28:

TABLE 28 nanometer active calcium carbonate Properties

The specific properties of the calcium silicate hydrate seeds are shown in table 29:

TABLE 29 seed Properties

The composite admixture adopts the comb-shaped structure polycarboxylate ether copolymer to compound the viscosity reducer and the defoaming agent, the mass ratio is (1000:5:1), and the specific properties are shown in Table 30:

TABLE 30 composite additive Properties

The synthetic fiber is POM type reinforced fiber with length-diameter ratio of phi 0.18 x 12 mm.

Firstly, weighing 450 parts of cement, 160 parts of fly ash-based admixture, 100 parts of ultrafine mineral powder, 60 parts of silica fume, 20 parts of nano-silica, 80 parts of nano-calcium carbonate, 185 parts of ceramsite particles, 240 parts of hollow glass beads, 60 parts of floating beads, 20 parts of seed crystals, 8 parts of shrinkage compensator, 40 parts of fibers, 130 parts of water and 50 parts of composite admixture according to the weight ratio.

Adding cement, fly ash-based admixture, superfine mineral powder, silica fume, nano-silica and nano-calcium carbonate into a stirrer, and stirring for 30s to obtain a mixed powder material; mixing 78 parts of water and 30 parts of an additive, uniformly stirring, adding the mixture into the glue powder, stirring for 4min, adding seed crystals, and stirring for 1min to obtain a slurry material; adding hollow glass beads and floating beads, adding a mixed solution of 26 parts of water and 10 parts of additive while stirring, and stirring for 2 min; adding POM synthetic fiber, continuously stirring for 1min, and simultaneously adding all the remaining water and additive mixed liquor in the stirring process; adding ceramic particles, stirring for 30s, then vacuumizing for 10s, pouring, vibrating for forming, covering a curing film, standing and curing for 12h under the conditions of 30 ℃ and 95 RH%, performing steam curing for 48h at 90 ℃, demolding, and naturally curing for 28d to obtain the ultralight ultrahigh-strength concrete.

Concrete volume weight and mechanical property detection is carried out according to the concrete mechanical property test method standard CB/T50081-plus 2019, and impermeability, carbonization resistance, chlorine ion erosion resistance and shrinkage property detection is carried out according to the GB/T50082-plus 2009 ordinary concrete long-term property and durability test method standard, and specific properties are shown in Table 31

Meter 31 ultra-light and ultra-high strength concrete performance detection

According to test results, the prepared light high-strength concrete has both ultra-light and ultra-high strength performances, and the ultra-high strength concrete with the compressive strength of more than or equal to 100MPaThe volume weight of the concrete is reduced to 1600kg/m³The minimum value is 1360kg/m³And has excellent durability such as impermeability, carbonization resistance, chlorine ion corrosion resistance and the like. Compared with the traditional ultrahigh-performance concrete, the volume weight of the concrete is 2600kg/m³And the weight reduction is realized by 40-50%.

The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.

Claims

1. The low-carbon ultra-light ultra-high-strength concrete is characterized by comprising the following raw materials in parts by weight: 400-450 parts of cement, 300-320 parts of multifunctional admixture, 90-100 parts of nano material, 230-300 parts of fine aggregate, 160-190 parts of coarse aggregate, 15-20 parts of seed crystal, 30-40 parts of fiber, 5-10 parts of shrinkage compensator, 40-50 parts of composite admixture and 110-130 parts of water;

the multifunctional admixture comprises a fly ash-based admixture, superfine mineral powder and silica fume;

the nano material comprises nano silicon dioxide and nano calcium carbonate;

the seed crystal is a calcium silicate hydrate gel nano composite material;

the composite additive is a comb-shaped polycarboxylic ether copolymer compounded cellulose ether viscosity reducer and a silicone defoaming agent.

2. The low-carbon ultra-light ultra-high-strength concrete according to claim 1, wherein the cement is high belite general purpose portland cement with a strength grade of 62.5 or more.

3. The low-carbon ultra-light ultra-high strength concrete according to claim 1, wherein the multifunctional admixture comprises 50-60 wt% of fly ash based admixture, 25-30 wt% of ultrafine mineral powder and 15-20 wt% of silica fume.

4. The low-carbon ultra-light ultra-high-strength concrete as claimed in claim 1 or 3, wherein the fly ash-based admixture is a high-specific-surface-area and high-activity admixture prepared by compounding and grinding I-class fly ash and alkali metal sulfate, and the specific surface area is not less than 700m²The activity index of the catalyst per kg and 7d is more than or equal to 120;

the fineness of the superfine mineral powder is more than or equal to 1000 meshes, and the activity is more than or equal to S120;

the purity of the silica fume is more than or equal to 96 percent.

5. The low-carbon ultra-light ultra-high strength concrete according to claim 1, wherein the nano material comprises 15-20% by weight of nano silica and 80-85% by weight of nano calcium carbonate.

6. The low-carbon ultra-light ultra-high strength concrete according to claim 1 or 5, wherein the purity of the nano silica is not less than 99%, and the average particle size is not more than 20 nm; the purity of the nano calcium carbonate is more than or equal to 98 percent, and the average grain diameter is less than or equal to 50 nm.

7. The low-carbon ultra-light ultra-high strength concrete of claim 1, wherein the fine aggregate comprises 70-80 wt% of hollow glass beads and 20-30 wt% of floating beads, wherein the true density of the hollow glass beads is less than or equal to 600kg/m³The compression density is more than or equal to 4000 psi; the apparent density of the floating bead is less than or equal to 700kg/m³The fineness is more than or equal to 80 meshes.

8. The low-carbon ultra-light ultra-high-strength concrete of claim 1, wherein the coarse aggregate is high-strength ceramic microspheres with the particle size of 5-10 mm, and the bulk density is less than or equal to 850kg/m³The cylinder pressure is more than or equal to 8 MPa.

9. The low-carbon ultra-light ultra-high strength concrete according to claim 1, wherein the calcium silicate hydrate gel nanocomposite has a solid content of 10% or more and a particle size of 40nm or less.

10. The low-carbon ultra-light ultra-high strength concrete according to claim 1, wherein the fibers are synthetic fibers made of polyoxymethylene.

11. The low carbon, ultra-light and ultra-high strength concrete of claim 1, wherein the shrinkage compensator is one or more of aluminosilicates, sulphoaluminates, calcium salts, magnesium salts.

12. The low-carbon ultra-light ultra-high strength concrete of claim 1, wherein the comb-structure polycarboxylate ether copolymer is formed by copolymerization and esterification of an acrylic-based polymer, a grafted organic amine salt and a shrinkage-reducing functional small monomer.

13. The low-carbon ultra-light ultra-high-strength concrete of claim 1, wherein the mass ratio of the comb-structure polycarboxylate ether copolymer, the cellulose ether viscosity reducer and the silicone defoamer in the composite admixture is 1000:5: 1.

14. the method for preparing the low-carbon ultra-light ultra-high-strength concrete according to claim 1, which comprises the following steps:

(1) weighing the component materials according to the proportion for later use;

(3) uniformly mixing (60-80)% of water and (60-80)% of composite additive in the step (1), adding the mixture into the powder in the step (2), stirring for 3-4 min, adding all seed crystals, and stirring;

(6) adding the coarse aggregate in the step (5), and stirring for 20-30 s;

(8) and after forming, standing and curing at the temperature of 20-30 ℃, then performing steam curing at the temperature of 50-90 ℃, removing the mold, and performing natural curing to obtain the low-carbon ultra-light ultra-high-strength concrete.

15. The method according to claim 14, wherein in the step (3), after all the seed crystals are added, the stirring time is 1 min.

16. The method according to claim 14, wherein in the step (8), the curing process is specifically as follows: standing and curing for 6-12 h under the conditions of 20-30 ℃ and more than or equal to 90 RH%, and then performing steam curing for 24-48 h at 50-90 ℃.

17. The low-carbon ultra-light ultra-high-strength concrete according to claim 1, wherein the volume weight is 1300-1600 kg/m³The cubic compressive strength is 100-120 MPa.