CN113773018A - Low-shrinkage high-crack-resistance ultrahigh-performance concrete and preparation method thereof - Google Patents
Low-shrinkage high-crack-resistance ultrahigh-performance concrete and preparation method thereof Download PDFInfo
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- 239000011374 ultra-high-performance concrete Substances 0.000 title claims abstract description 68
- 238000002360 preparation method Methods 0.000 title abstract description 14
- 239000004567 concrete Substances 0.000 claims abstract description 32
- 238000003756 stirring Methods 0.000 claims abstract description 32
- 239000000835 fiber Substances 0.000 claims abstract description 30
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 26
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000004568 cement Substances 0.000 claims abstract description 25
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 24
- 239000010959 steel Substances 0.000 claims abstract description 24
- 239000000843 powder Substances 0.000 claims abstract description 22
- 239000004576 sand Substances 0.000 claims abstract description 21
- 239000004575 stone Substances 0.000 claims abstract description 14
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 12
- 239000002002 slurry Substances 0.000 claims abstract description 12
- 239000000203 mixture Substances 0.000 claims abstract description 8
- 229910021487 silica fume Inorganic materials 0.000 claims abstract description 8
- 239000011248 coating agent Substances 0.000 claims abstract description 4
- 238000000576 coating method Methods 0.000 claims abstract description 4
- 238000000465 moulding Methods 0.000 claims abstract description 4
- 238000012423 maintenance Methods 0.000 claims abstract description 3
- 239000000463 material Substances 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 12
- 239000002131 composite material Substances 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 7
- UFLSLGGVXPPUDQ-UHFFFAOYSA-N dicalcium oxygen(2-) Chemical group [O--].[O--].[Ca++].[Ca++] UFLSLGGVXPPUDQ-UHFFFAOYSA-N 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 4
- 239000011575 calcium Substances 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 4
- 239000000292 calcium oxide Substances 0.000 claims description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 4
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 239000011398 Portland cement Substances 0.000 claims description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- 230000008901 benefit Effects 0.000 abstract description 6
- 235000013312 flour Nutrition 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 25
- 230000002829 reductive effect Effects 0.000 description 14
- 238000005336 cracking Methods 0.000 description 12
- 230000000694 effects Effects 0.000 description 12
- 230000036571 hydration Effects 0.000 description 11
- 238000006703 hydration reaction Methods 0.000 description 11
- 229910052500 inorganic mineral Inorganic materials 0.000 description 4
- 239000011707 mineral Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000004566 building material Substances 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 208000010392 Bone Fractures Diseases 0.000 description 2
- 206010017076 Fracture Diseases 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000012412 chemical coupling Methods 0.000 description 2
- 230000001808 coupling effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000007580 dry-mixing Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 229910001653 ettringite Inorganic materials 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/38—Fibrous materials; Whiskers
- C04B14/48—Metal
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/12—Waste materials; Refuse from quarries, mining or the like
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/06—Oxides, Hydroxides
- C04B22/062—Oxides, Hydroxides of the alkali or alkaline-earth metals
- C04B22/064—Oxides, Hydroxides of the alkali or alkaline-earth metals of the alkaline-earth metals
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/08—Acids or salts thereof
- C04B22/14—Acids or salts thereof containing sulfur in the anion, e.g. sulfides
- C04B22/142—Sulfates
- C04B22/143—Calcium-sulfate
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/08—Acids or salts thereof
- C04B22/14—Acids or salts thereof containing sulfur in the anion, e.g. sulfides
- C04B22/142—Sulfates
- C04B22/148—Aluminium-sulfate
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/34—Non-shrinking or non-cracking materials
- C04B2111/343—Crack resistant materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Civil Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mining & Mineral Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention discloses a low-shrinkage high-crack-resistance ultrahigh-performance concrete and a preparation method thereof, wherein the concrete comprises the following components in parts by weight: 400-500 parts of cement, 150-200 parts of silica fume, 400-500 parts of mountain flour, 750-800 parts of fine sand, 200-250 parts of coarse sand, 150-180 parts of fiber, 33-40 parts of water reducing agent, 190-200 parts of water and 40-60 parts of expanding agent. The preparation method comprises pouring cement, silica fume, stone powder and expanding agent into a concrete stirring pot, and stirring uniformly; adding fine sand and coarse sand, and stirring uniformly; pouring 50% of water and a mixture of the residual water and the water reducing agent, and stirring until slurry is formed; continuously stirring the slurry, and slowly adding the steel fiber; pouring, vibrating and molding, coating a film on the surface, and removing the film after 1 day for standard maintenance to obtain the low-shrinkage high-crack-resistance ultrahigh-performance concrete. The low-shrinkage high-crack-resistance ultrahigh-performance concrete prepared by the invention has good working performance, simple preparation method, less pollution, and good economic benefit and engineering application value.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to low-shrinkage high-crack-resistance ultrahigh-performance concrete and a preparation method thereof.
Background
Ultra-high performance concrete (UHPC) refers to a novel cement-based building material with ultrahigh strength (compressive strength is more than or equal to 150MPa), high durability and high toughness. UHPC improves the gradation of particles, reduces internal defects and improves the compactness and uniformity of materials by removing coarse aggregates and using fine sand with the thickness of about 1mm as aggregates according to the close packing principle; the volcanic ash effect and the filling effect of the active mineral admixtures such as the silica fume, the fly ash and the mineral powder are utilized, so that the pore structure of the material is improved; by using the polycarboxylic acid high-efficiency water reducing agent, the water-cement ratio is greatly reduced, and the porosity is reduced, so that the concrete material with excellent performance is obtained.
Because the performance of UHPC meets the requirements of larger span, larger bearing capacity and smaller self weight of the current building engineering structure, and the high durability of the UHPC in a severe environment, the UHPC shows wide application prospect, receives extensive attention and becomes a hotspot of research in the field of building materials. However, the magic spell of "concrete without non-cracking" is also reflected on UHPC without a hundred percent perfect material, and the risk of shrinkage cracking is even greater than that of ordinary concrete due to the self-configured characteristics of UHPC. UHPC eliminates coarse aggregate, reduces the inhibition effect of the aggregate on the shrinkage of a matrix, and has larger shrinkage; the ultra-low water-to-gel ratio, high activity admixtures, and high cement dosage result in very low internal humidity of UHPC, and self-contraction caused by capillary pressure is much greater than that of ordinary concrete. High cement usage also increases hydration heat release, causing increased temperature distortion. When the tensile stress caused by the internal shrinkage and temperature deformation of the UHPC is larger than the tensile strength of the concrete, the concrete can crack. The appearance of the cracking phenomenon not only influences the appearance of the building, but also provides a channel for external erosion media to enter the concrete, thereby seriously shortening the service life of the building, even changing the bearing capacity of the concrete structure and threatening the use safety.
The method for compensating shrinkage cracking by doping an expanding agent into concrete is a good means for solving the problem of shrinkage cracking, and currently, calcium oxide, calcium sulphoaluminate, magnesium oxide and calcium oxide-calcium sulphoaluminate composite expanding agents are mainly used in the market. However, the reaction characteristics, the expansion generation time, the water demand and the expansion amount of each expanding agent are different, and the shrinkage of UHPC is greatly different from that of common concrete, wherein the UHPC mainly has self-shrinkage, the early shrinkage has high development rate and large shrinkage, and the later shrinkage is only small. Therefore, the mixing amount and matching property of the expanding agent in UHPC are worth studying.
At present, UHPC is mainly applied to concrete products with smaller size structures such as architectural ornaments, steel-UHPC combined bridge deck pavement, prefabricated product components and the like, and the application and development of the concrete products are limited by the larger shrinkage cracking risk of the UHPC for large-volume engineering structures. Therefore, it is urgently needed to design a low-shrinkage high-crack-resistance ultra-high performance concrete according to the characteristics of UHPC.
Disclosure of Invention
The invention aims to: overcomes the defects in the prior art, and provides the low-shrinkage high-crack-resistance ultra-high performance concrete and the preparation method thereof. The UHPC in the invention reduces hydration heat and shrinkage of the ultra-high performance concrete in all directions by the physical and chemical coupling action of low cement dosage, steel fiber and calcium oxide-calcium sulphoaluminate composite expanding agent, improves tensile strength and toughness, and achieves the effects of low shrinkage and high crack resistance. In addition, the UHPC prepared by the invention has good working performance, simple preparation method, less pollution, and good economic benefit and engineering application value.
In order to achieve the purpose, the invention adopts the following technical scheme:
the low-shrinkage high-crack-resistance ultrahigh-performance concrete comprises the following components in parts by mass:
in the invention, the cement is ordinary portland cement with the strength grade not less than 42.5, and the average particle size is 8-15 μm.
The mass content of silicon dioxide in the silica fume is more than or equal to 93 percent, the average particle size is 0.3-1.2 mu m, and the specific surface area is not less than 16000m2/kg。
The calcium carbonate content in the stone powder is more than 95 wt%, and the average particle size is 8-15 μm.
The fine sand is continuous graded sand with the particle size range of 0-0.6 mm. The coarse sand is continuous graded sand with the particle size range of 0.6-1.25 mm.
The fiber is copper-plated steel fiber with the length of 6-15 mm, the diameter of 0.1-0.3 mm and the elastic modulus of not less than 50 GPa.
The water reducing agent is a polycarboxylic acid water reducing agent, the solid content is 20%, and the effective water reducing rate is more than 40%.
The expanding agent is a calcium oxide-calcium sulphoaluminate compound expanding agent, wherein:
40 to 50 percent of calcium oxide;
2 to 10 percent of calcium sulphoaluminate;
15 to 30 percent of calcium sulfate.
In the invention, cement is replaced by the mineral admixture stone powder with large mixing amount, so that the hydration heat of UHPC is reduced, and the temperature deformation is reduced. The concrete releases heat due to hydration of internal cement, heat is difficult to dissipate through the surface in a short time, a high internal and external temperature difference can be formed, and the temperature difference of mass concrete can reach 30-40 ℃ at most. Concrete temperature change can cause the volume to warp, and the volume expansion that releases heat in early stage, and later stage cooling is and is shrunk, because of the restraint of structures such as basement and reinforcing bar, concrete expansion and shrink all can produce tensile stress, bring the fracture risk. In addition, because the water-to-cement ratio of UHPC is very low (generally less than 0.2), cement in concrete cannot react sufficiently, resulting in resource wasteAnd (4) charging. The stone powder with equivalent grain size is used for replacing cement, thereby not only reducing the cracking risk, but also obviously reducing the cost of UHPC and reducing the greenhouse gas CO2The discharge of the catalyst is beneficial to the popularization and application of UHPC.
In the invention, the shrinkage of UHPC is compensated by adding the calcium oxide-calcium sulphoaluminate composite expanding agent to generate proper expansion in the early stage. Due to the characteristics of low water-gel ratio, no coarse aggregate and high gel material content of the UHPC, the shrinkage of the UHPC is greatly different from that of common concrete, which is shown in the fact that the UHPC self-shrinkage is far larger than the drying shrinkage, and the trend of large early shrinkage, fast shrinkage and later-stage micro-shrinkage is shown. The calcium oxide-calcium sulphoaluminate composite expanding agent is preferably selected, the double-expansion-source expanding agent generates calcium hydroxide through hydration of calcium oxide in the early stage, calcium sulphoaluminate is hydrated to form ettringite to generate expansion, the double-expansion-source expanding agent has the characteristics of large early-stage expansion amount, good absolute wet expansibility and long-term stability, is matched with UHPC (ultra high performance polycarbonate) shrinkage, and can effectively compensate the shrinkage.
In the invention, the steel fiber and the expanding agent are physically and chemically coupled to enhance and toughen and inhibit shrinkage. The UHPC is doped with the fiber, so that the compressive strength, the tensile strength and the fracture energy of the concrete can be improved, the concrete has certain toughness from brittleness, and the composite material theory and the fiber spacing theory mainly exist. And the steel fiber and the expanding agent are used in a composite way, the hydration product of the expanding agent can fill the gap, the binding force of the steel fiber and the matrix is enhanced, and in turn, the steel fiber has the effects of limiting expansion and contraction, the internal structure of the concrete is improved, and when the expanding agent has residues, self-stress can be generated, and the integral compactness is improved.
According to the invention, the mass ratio of each powder with different particle sizes in the matrix is designed and determined through a corrected Anderson close packing model, so that the compactness and the performance of the low-shrinkage high-crack-resistance UHPC are ensured.
The invention discloses a preparation method of low-shrinkage high-crack-resistance ultrahigh-performance concrete, which specifically comprises the following steps of:
a. weighing the raw materials according to the mass component ratio;
b. pouring the powder materials of the cement, the silica fume, the stone powder and the expanding agent into a concrete stirring pot, and dry-stirring for 30s at a rotating speed of 80-100 r/min to ensure that the cementing material is uniformly distributed;
c. adding the fine sand and the coarse sand into a stirring pot, continuously performing dry stirring at a rotating speed of 80-100 r/min for 60s, and uniformly stirring;
d. pouring 50% of the water into the stirring pot, uniformly mixing the remaining 50% of the water with the water reducing agent after 30s, and adding the mixture into the stirring pot until slurry is formed;
e. d, continuously stirring the slurry obtained in the step d for 180 seconds, slowly adding steel fibers, and stirring for 60 seconds;
f. pouring, vibrating and molding, coating a film on the surface, and removing the film after 1 day for standard maintenance to obtain the low-shrinkage high-crack-resistance ultrahigh-performance concrete.
The preparation method provided by the invention is different from the method that the fine aggregate is added after the slurry is formed in the common UHPC concrete preparation process, the gelled material and the sand with larger grain diameter are simultaneously stirred, and the friction force and the shearing force between powder materials are improved by utilizing the resistance between the mixture and the inner wall of the mortar stirring pot, so that the dispersion of water and the water reducing agent is facilitated, and the slurry forming time is shortened. In addition, different from the method of uniformly mixing the steel fiber and the powder and then adding water and the water reducing agent for stirring, the mixture is stirred into slurry firstly, and then the steel fiber is added, so that the steel fiber can be effectively dispersed by utilizing the slurry, the lapping and agglomeration of the steel fiber entering the interior can be reduced, and the damage of sand powder to copper plating on the surface of the steel fiber and the bending deformation of the steel fiber can be reduced.
Compared with the prior art, the invention has the following advantages and beneficial effects:
according to the low-shrinkage high-crack-resistance ultrahigh-performance concrete and the preparation method thereof disclosed by the invention, cement is replaced by the large-doping-amount mineral admixture stone powder, and the mix proportion design is carried out again according to a compact stacking model, so that the hydration heat and the temperature deformation are reduced, the environmental pollution is reduced, the economic benefit and the environmental protection benefit are good, and the working performance and the internal structure of UHPC are improved by doping the stone powder. The physical and chemical coupling effect of the steel fiber and the expanding agent is utilized to enhance and toughen and compensate the shrinkage. The UHPC prepared by the invention has low shrinkage and high crack resistance, solves the problem that the UHPC test piece is easy to crack in engineering practice to influence the service life, and has wide application prospect and value. The preparation method provided by the invention has the advantages of simple operation, easy implementation and low cost.
Drawings
FIG. 1 is a hydration heat map of comparative and example concrete;
FIG. 2 is a 7 day self-contraction plot for comparative examples and examples.
Detailed Description
The present invention provides a low shrinkage, high crack resistance and ultra high performance concrete and a method for preparing the same, and in order to clearly and intuitively show the objects, technical solutions and advantageous effects of the present invention, specific embodiments will be described in detail below. It should be understood that the illustrated examples are only intended to illustrate the present invention, and the present invention is not limited by the scope of the illustrated examples.
Examples and comparative examples
The present invention provides three comparative examples and two examples of different components, showing the improvement of the performance of the ultra high performance concrete of the present invention by comparison, and the parts by weight of each component are shown in table 1.
TABLE 1 raw material ratios (kg/m) of comparative example and example3)
All the parameters of the raw materials in the comparative example are consistent with the requirements in the technical scheme adopted by the invention, and the fibers in the table are steel fibers.
Comparative example 1 corresponds to a blank control; compared with the comparative example 1, the cement is replaced by the stone powder, so that the cement consumption is reduced; comparative example 3 compared to comparative example 1, the cement was reduced and 2% steel fiber was incorporated, compared to comparative example 2, the steel fiber was increased; example 1 is a group of preferred formulation of the low shrinkage and high crack resistance UHPC of the present invention, compared to comparative example 1, the amount of cement is reduced, and the expanding agent and steel fiber are added.
The preparation method of the low-shrinkage high-crack-resistance ultrahigh-performance concrete comprises the following specific steps:
s1, weighing the raw materials according to the mass component ratios in Table 1;
s2, pouring the powder materials of the cement, the silica fume, the stone powder and the expanding agent into a concrete mixing pot, and dry-mixing for 30S at the rotating speed of 100r/min to ensure that the cementing material is uniformly distributed;
s3, adding the fine sand and the coarse sand into a stirring pot, continuously performing dry stirring for 60S at the rotating speed of 100r/min, and uniformly stirring;
s4, pouring 50% of the water into a stirring pot, mixing the remaining 50% of the water with a water reducing agent uniformly after 30S, and adding the mixture into the stirring pot until slurry is formed;
s5, continuously stirring the slurry obtained in the step S4 for 180S, slowly adding the steel fibers, and stirring for 60S;
s6 pouring, vibrating and molding, coating a film on the surface, and removing the film after 1 day for standard curing to obtain the low-shrinkage high-crack-resistance ultra-high performance concrete.
Table 2 shows the results of the performance tests of the concrete for 3 days and 28 days obtained in the comparative examples and examples according to the above-mentioned procedures.
TABLE 2 working and mechanical Properties test results
As can be seen from comparative example 1 and comparative example 2 in Table 2, the use of stone powder instead of cement in comparative example 2 can significantly improve the fluidity of UHPC; as can be seen from comparative examples 2 and 3, the steel fiber has obvious improvement effect on the compressive strength, the flexural strength and the tensile strength of the UHPC; as can be seen from the comparison of example 1 with comparative example 3, the strength of UHPC is slightly reduced after the addition of the expanding agent, but the amplitude is small, and the strength reaches 138MPa after 28 days.
As shown in the hydration heat maps of the concrete of comparative example and example in FIG. 1, when cement was replaced with stone powder, the amount of hydration heat of UHPC was significantly reduced as compared with that of comparative example 1, and the reduction of the hydration heat of concrete improved the temperature deformation and cracking.
Fig. 2 shows that steel fiber, low cement content and expanding agent have the effect of reducing shrinkage of UHPC, the effect of reducing shrinkage of comparative example 2, comparative example 3 and example 1 is very obvious compared with that of comparative example 1, and the expanding agent added in example 1 has the characteristics of large early expansion amount, good absolute wet expansion and long-term stability, so that the curve shows the tendency that the shrinkage rate at early stage is slightly increased and then reduced, and finally stabilized, and the self-shrinkage of example 1 only accounts for 35% -50% of that of comparative example 1.
The results of the plate restraint cracking test are shown in Table 3.
TABLE 3 results of plate crack data processing
In table 3, the smaller the number of cracks, the smaller the maximum crack width, the smaller the average crack area per crack, the smaller the number of cracks per unit area and the total crack area, and the higher the crack resistance index, the better the crack resistance effect. Comparing the plate cracking test data, it can be seen that example 1 exhibits the best cracking resistance effect, wherein the cracking resistance index is up to 75.54%.
The comprehensive comparison between the examples and the comparative examples shows that the low-shrinkage high-crack-resistance ultrahigh-performance concrete (see example 1) provided by the invention has good shrinkage and crack resistance inhibiting effect and improved working performance.
Claims (10)
1. The low-shrinkage high-crack-resistance ultrahigh-performance concrete is characterized by comprising the following components in parts by mass:
2. the low-shrinkage high-crack-resistance ultra-high-performance concrete according to claim 1, wherein: the cement is ordinary portland cement with the strength grade not less than 42.5, and the average particle size is 8-15 mu m.
3. The low-shrinkage high-crack-resistance ultra-high-performance concrete according to claim 1, wherein: the average particle size of the silica fume is 0.3-1.2 mu m, and the specific surface area is not less than 16000m2Per kg, wherein the mass content of the silicon dioxide is more than or equal to 93 percent.
4. The low-shrinkage high-crack-resistance ultra-high-performance concrete according to claim 1, wherein: the average particle size of the stone powder is 8-15 mu m, and the content of calcium carbonate in the stone powder is more than 95 wt%.
5. The low-shrinkage high-crack-resistance ultra-high-performance concrete according to claim 1, wherein: the fine sand is continuous graded sand with the particle size range of 0-0.6 mm.
6. The low-shrinkage high-crack-resistance ultra-high-performance concrete according to claim 1, wherein: the coarse sand is continuous graded sand with the particle size range of 0.6-1.25 mm.
7. The low shrinkage, high crack resistance and ultra-high performance concrete according to claim 1, wherein; the fiber is copper-plated steel fiber with the length of 6-15 mm, the diameter of 0.1-0.3 mm and the elastic modulus of not less than 50 GPa.
8. The low-shrinkage high-crack-resistance ultra-high-performance concrete according to claim 1, wherein: the water reducing agent is a polycarboxylic acid water reducing agent, the solid content is 20%, and the effective water reducing rate is more than 40%.
9. The concrete of claim 1, wherein the expansion agent is a calcium oxide-calcium sulfoaluminate composite expansion agent, wherein:
40 to 50 percent of calcium oxide;
2 to 10 percent of calcium sulphoaluminate;
15 to 30 percent of calcium sulfate.
10. A method for preparing the low shrinkage high crack resistance ultra-high performance concrete according to any one of claims 1 to 9, characterized by comprising the steps of:
a. weighing the raw materials according to the mass component ratio;
b. pouring the powder materials of the cement, the silica fume, the stone powder and the expanding agent into a concrete stirring pot, and dry-stirring for 30s at a rotating speed of 80-100 r/min to ensure that the cementing material is uniformly distributed;
c. adding the fine sand and the coarse sand into a stirring pot, continuously performing dry stirring at a rotating speed of 80-100 r/min for 60s, and uniformly stirring;
d. pouring 50% of the water into the stirring pot, uniformly mixing the remaining 50% of the water with the water reducing agent after 30s, and adding the mixture into the stirring pot until slurry is formed;
e. d, continuously stirring the slurry obtained in the step d for 180 seconds, slowly adding steel fibers, and stirring for 60 seconds;
f. pouring, vibrating and molding, coating a film on the surface, and removing the film after 1 day for standard maintenance to obtain the low-shrinkage high-crack-resistance ultrahigh-performance concrete.
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