CN114507041A - Low-thixotropic ultrahigh-performance concrete and preparation method thereof - Google Patents
Low-thixotropic ultrahigh-performance concrete and preparation method thereof Download PDFInfo
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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
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/04—Silica-rich materials; Silicates
- C04B14/06—Quartz; Sand
- C04B14/068—Specific natural sands, e.g. sea -, beach -, dune - or desert sand
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/302—Water reducers
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
- C04B2201/52—High compression strength concretes, i.e. with a compression strength higher than about 55 N/mm2, e.g. reactive powder concrete [RPC]
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- 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
Abstract
The invention discloses low-thixotropy ultrahigh-performance concrete and a preparation method thereof. The low-thixotropy ultrahigh-performance concrete comprises the following components in parts by mass: 400-800 parts of cement, 50-300 parts of silica fume, 100-500 parts of a functional admixture, 400-1000 parts of sand, 0-800 parts of broken stone, 5-240 parts of fiber, 5-20 parts of a functional assistant, 10-40 parts of a water reducing agent and 120-180 parts of water. The low-thixotropy ultra-high performance concrete disclosed by the invention has lower thixotropy, can still keep higher fluidity in a standing state or a low shear rate state, prolongs the construction time of the ultra-high performance concrete, and ensures that the ultra-high performance concrete has higher compactness in the pouring process. In addition, the material of the invention also has low viscosity, ultrahigh strength, low shrinkage, higher elastic modulus and ultrahigh durability.
Description
Technical Field
The invention belongs to the technical field of building materials, and relates to ultra-high performance concrete, in particular to low-thixotropic ultra-high performance concrete and a preparation method thereof.
Background
The Ultra-high performance concrete (UHPC) has Ultra-high strength, high toughness and excellent durability, and can well meet the requirements of lightweight, high-rise, large-span and high durability of civil engineering structures. UHPC has the characteristics of high cementing material consumption, high content of ultrafine powder, extremely low water-gel ratio and the like, so that the particle spacing in concrete is extremely small, the particle acting force is strong, the forming speed of a flocculation structure is extremely fast, and the concrete has extremely high thixotropy. The excellent rheological property is the key for ensuring the UHPC to be poured smoothly and exerting the performance advantage thereof. There are significant differences in the demands for UHPC rheology from different casting methods. When the pumping construction is adopted, the high thixotropy can improve the sedimentation problem of high-flow UHPC aggregate and fiber, and reduce the risk of pump blockage. However, when the conventional hopper is adopted for transportation and pouring, the static working performance loss of the UHPC is obvious due to high thixotropy, the construction time is short, air bubbles are difficult to discharge in the pouring process, the compactness is poor, and the construction performance and the engineering quality are seriously influenced. In order to ensure the construction quality of the UHPC bridge deck slab in projects such as Nanjing five-bridge, the problem of UHPC compactness caused by high thixotropy is solved by adopting an inserting and tamping process, so that the construction efficiency is obviously reduced, and the construction cost is greatly increased. Therefore, the regulation and control of UHPC thixotropy are very important for construction and quality guarantee.
Patent CN2017102107384 discloses decorative ultra-high performance concrete easy to pump, which is prepared from white cement, silica fume, metakaolin, quartz sand, color, water reducing agent, magnesium aluminum silicate, cellulose ether, fiber and the like. The technology of the patent improves the thixotropy of the ultra-high performance concrete through magnesium aluminum silicate.
CN 201810359730.9 discloses a concrete thixotropic agent, which is a concrete thixotropic agent solution taking quaternary ammonium salt polymer, superfine powder and fiber as main components to increase the thixotropy of concrete and improve the construction and use performance of non-self-compacting concrete.
CN 201610894393.4 discloses a thixotropic agent for a polycarboxylate water reducer, which takes white carbon black, alkali carbonate and sulfate as main raw materials to enhance the thixotropy of fresh concrete of a prefabricated part.
However, the concrete thixotropy control technology is mainly used for enhancing the thixotropy of concrete, and is in contradiction with the requirement of low thixotropy in conventional UHPC (ultra high performance concrete) pouring. At present, the technology for reducing the thixotropy of concrete is rarely reported. CN 201610110268. X discloses a low-thixotropy self-extinction coating and a preparation method thereof, wherein the low-thixotropy self-extinction coating is prepared from silicon modified acrylic resin, acrylic acid acrylic resin, isooctyl acrylate, hydroxyethyl methacrylate, a photoinitiator, a dispersant, a leveling agent, an extinction powder, a surfactant, an antifoaming agent and the like, and the thixotropy of the coating is reduced mainly by a silicon-containing medium solid auxiliary agent (surfactant) and a macromolecular dispersant. However, the technical measures are mainly applied to the oil-based coating to improve the dispersion state of the coating, and cannot be effectively applied to the field of concrete due to the difference of technical principles and the problem of compatibility.
Disclosure of Invention
Aiming at the difficult problems that the conventional ultrahigh-performance concrete has large thixotropy, serious standing loss and short construction time, and seriously influences the construction progress and the pouring compactness, the invention provides the low-thixotropy ultrahigh-performance concrete,
the rheological property of the ultra-high performance concrete is improved, the interaction among particles is reduced, the reconstruction rate and the structural strength of a flocculation structure are reduced, the early thixotropic property of the ultra-high performance concrete is obviously reduced, the ultra-high performance concrete still keeps higher fluidity in a standing state or a low shear rate state, the construction time of the ultra-high performance concrete is prolonged, and the higher compactness in the pouring process of the ultra-high performance concrete is ensured. In addition, the low-thixotropy ultrahigh-performance concrete disclosed by the invention not only has low thixotropy, but also has low viscosity, low shrinkage, ultrahigh strength, ultrahigh toughness, higher elastic modulus and ultrahigh durability.
The low-thixotropy ultrahigh-performance concrete disclosed by the invention comprises the following components in parts by mass:
400-800 parts of cement, namely cement,
50-300 parts of silica fume,
100-500 parts of a functional admixture,
400-1000 parts of sand,
5 to 240 parts of fiber, and a fiber,
5-20 parts of functional auxiliary agent
10-40 parts of water reducing agent
120-180 parts of water;
the cement is Portland cement or ordinary Portland cement with the strength grade of 42.5 or above, and the average grain diameter is 10-20 mu m;
SiO in the silica fume2The content is more than 90 percent, and the average grain diameter of the silica fume is 0.2-5 mu m;
the functional admixture is formed by mixing corundum powder and any one or more than two of zirconium micro silicon powder, ultrafine fly ash and glass powder; wherein the average grain diameter of the zirconium micro silicon powder is 5-10 mu m, and SiO is2The content is more than 60 percent; the average particle size of the ultrafine fly ash is 5-20 μm; the average particle size of the glass powder is 20-200 mu m; what is needed isThe corundum powder is spherical particles, and the average particle size is 200-800 mu m; and the functional admixture at least contains more than 30wt% of corundum powder.
The sand is continuous graded sand with the particle size of 0.075-4.75 mm;
the fibers are synthetic fibers and/or metal fibers; wherein the synthetic fiber is any one of polypropylene fiber, polyvinyl alcohol fiber and polyformaldehyde fiber, the length is 3-20 mm, and the diameter is 40-200 mu m; the metal fiber is steel fiber, the length of the metal fiber is 3-30 mm, and the diameter of the metal fiber is 0.1-0.3 mm;
the functional auxiliary agent is a mixture of any two or more than three of sodium sulfate, calcium sulfate or sodium dodecyl sulfate and 3-methyl-1, 5-pentanediol, sodium formate, calcium hypophosphite, sodium tripolyphosphate, ethylene diamine tetra methyl sodium phosphonate and 2-butane phosphonate-1, 2, 4-tricarboxylic acid tetrasodium; and the dosage of sodium sulfate, calcium sulfate or sodium dodecyl sulfate in the functional additive is not less than 15% and not more than 35%.
The water reducing agent is prepared from a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and a polyether modified organic silicon type defoaming agent (30-90): (5-60): (2-60): (1.5-5): (0.5-1).
As an improvement, the low-thixotropy ultra-high performance concrete is also added with macadam, and the using amount of the macadam is not more than 800 parts;
the broken stone is any one of limestone, granite, diabase and basalt, and the particle size of the broken stone is 4.75-19 mm.
As a further improvement, the mass of the zirconium micro-silicon powder in the functional admixture accounts for 30-50wt% of the total mass of the functional admixture.
As a further improvement, the functional additive is added with a combination of inorganic phosphate and organic phosphonate of calcium hypophosphite and/or sodium tripolyphosphate and sodium ethylene diamine tetramethylphosphonate or tetrasodium 2-phosphonate butane-1, 2, 4-tricarboxylate, and the dosage ranges of the inorganic phosphate and the organic phosphonate are (1-2): (2-1).
The preparation method of the low-thixotropic ultrahigh-performance concrete comprises the following steps of: firstly, mixing cement, silica fume, a functional admixture, sand and broken stones for 0.5-2 min, then adding a functional auxiliary agent, water and a water reducing agent which are mixed in advance, stirring for 5-10 min, and finally adding fibers, and stirring for 2-4 min to obtain the low-thixotropic ultrahigh-performance concrete.
The invention has the beneficial effects that:
(1) by using the zirconium micro silicon powder, the ultrafine fly ash, the glass powder and the spherical corundum powder, the dispersibility of cement and silica fume particles is improved, the mutual contact probability of the cement particles and the silica fume particles is reduced, the forming rate of a flocculation structure in concrete is reduced, and the thixotropy is reduced; in addition, the powder with different particle diameters can optimize the particle size distribution of the total powder, improve the stacking compactness of the particles and effectively reduce the viscosity of the ultra-high performance concrete.
(2) The early C3A hydration rate is reduced through sodium sulfate, sodium dodecyl sulfate, 3-methyl-1, 5-pentanediol, sodium formate, calcium hypophosphite, sodium tripolyphosphate, ethylene diamine tetra methyl sodium phosphonate and 2-butane phosphonate-1, 2, 4-tricarboxylic acid tetrasodium, the formation of early ettringite is reduced, the bridging effect of the ettringite on the surfaces of cement and silica fume is reduced, the interparticle acting force is reduced, and the thixotropy of the ultra-high performance concrete is further reduced.
(3) The compound high-performance water reducing agent is adopted, based on the selective absorption characteristic of powder, the absorption behavior of the water reducing agent on the surface of the powder is improved through the carboxylic acid-based high-performance water reducing agent, the phosphonic acid-based high-performance water reducing agent, the lignosulfonate, the acrylate and the like, the uniform absorption of the water reducing agent on the surfaces of all the powder is realized, the uniform and rapid dispersion of various powder in the ultra-high-performance concrete with extremely low water-gel ratio is realized, the agglomeration problem of the ultra-fine powder in slurry due to the ultra-strong interparticle acting force is reduced, the forming rate of a flocculation structure is reduced, the thixotropy of the ultra-high-performance concrete is reduced, and the concrete has higher fluidity in a standing state or at a low shearing rate is realized.
(4) The ultrahigh strength and the ultrahigh toughness of the ultrahigh-performance concrete are realized by doping silica fume, fibers and a low water-to-gel ratio; the problem of air content increase caused by large-dosage fiber and water reducing agent is solved by introducing the defoaming agent, and the compactness of the ultrahigh-performance concrete is ensured.
By the technical measures, the prepared ultra-high performance concrete has lower thixotropy and still keeps higher fluidity in a standing state or a low shear rate state; in addition, the rubber also has low viscosity, ultrahigh strength, low shrinkage, higher elastic modulus and ultrahigh durability.
Detailed Description
To more fully explain the practice of the present invention, the following examples of the preparation of low thixotropic ultra high performance concrete are provided. These examples are merely illustrative and do not limit the scope of the invention.
The "cement" in the examples is P.II 52.5 portland cement.
The "silica fume" in the examples is an Angen 97 grade silica fume, SiO2The content is 97 percent, and the average grain diameter is 0.5 mu m;
in the functional admixture of the examples, the "zirconium micro silica powder" had an average particle diameter of 5.7 μm and SiO2The content is more than 78 percent; the average particle size of the ultrafine fly ash is 10 mu m; the average grain diameter of the glass powder is 60 mu m; the average grain diameter of the spherical corundum powder is 150 mu m;
the sand in the embodiment is continuous river sand with the particle size of 0.075-4.75 mm;
in the embodiment, the crushed stone is basalt crushed stone with 4.75-19 mm of grain size in continuous gradation;
in the embodiment, the synthetic fiber in the fiber is polyformaldehyde fiber, the length is 6mm, and the diameter is 100 μm; the metal fiber is straight steel fiber with the length of 13mm and the diameter of 0.2 mm.
TABLE 1 content of each component of the ultra-high Performance Cement-based repair Material in each example
In the embodiment 1, the functional admixture is zirconium micro silicon powder, glass powder and corundum powder, and the mass ratio is 30: 25: mixing at a ratio of 35; the fiber is straight steel fiber; the functional auxiliary agent is sodium sulfate, 3-methyl-1, 5-pentanediol, sodium formate, calcium hypophosphite and ethylene diamine tetra methyl sodium phosphonate, and the mass ratio is (20): 25: 10: 30: 15, mixing in proportion; the water reducing agent is a carboxylic acid-based high-performance water reducing agent: the weight ratio of phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent is 60: 35: 3: 1.5: mixing at a ratio of 0.5.
In the embodiment 2, the functional admixture is zirconium micro silicon powder, fine grinding fly ash and corundum powder, and the weight ratio of the zirconium micro silicon powder to the fine grinding fly ash to the corundum powder is 50: 20: mixing at a mass ratio of 30; the fiber is steel fiber; the functional auxiliary agent is sodium sulfate, 3-methyl-1, 5-pentanediol, calcium hypophosphite, sodium formate and sodium tripolyphosphate, and the mass ratio of the functional auxiliary agent is 10: 25: 15: 25: mixing at a ratio of 25; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent is 76: 20: 2: 1.5: mixing at a ratio of 0.5.
In the embodiment 3, the functional admixture is zirconium micro silicon powder and corundum powder, and the weight ratio of the zirconium micro silicon powder to the corundum powder is 30: mixing at a mass ratio of 70; the fiber is straight fiber; the functional auxiliary agent is calcium sulfate, calcium hypophosphite and 2-phosphonic acid butane-1, 2, 4-tricarboxylic acid tetrasodium according to the mass ratio of 20: 30: mixing at a ratio of 60; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent to the water reducing agent is 49.5: 45: :3: 2: mixing at a ratio of 0.5.
In example 4, the functional admixture is zirconium micro-silica powder, ultra-fine fly ash, glass powder, and corundum powder, and the mass ratio is 30: 15: 15: mixing at a ratio of 40; the fiber is polyformaldehyde fiber and straight steel fiber according to the mass ratio of 5: mixing at a ratio of 95; the functional auxiliary agent is sodium dodecyl sulfate, 3-methyl-1, 5-pentanediol, sodium tripolyphosphate and ethylene diamine tetra methyl sodium phosphonate, and the mass ratio is 35: 20: 15: mixing at a ratio of 30; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent is 80: 15: 2.5: 2: mixing at a ratio of 0.5.
In example 5, the functional admixture is zirconium micro-silica powder, ultra-fine fly ash and corundum powder according to the mass ratio of 35: 20: mixing at a ratio of 45; the fiber is straight steel fiber; the functional auxiliary agent is sodium sulfate, sodium dodecyl sulfate, 3-methyl-1, 5-pentanediol, calcium hypophosphite and sodium tripolyphosphate, and the mass ratio of the functional auxiliary agent is (20): 15: 35: 15: 15, mixing in proportion; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent is 54: 40: 3.5: 1.5: mixing at a ratio of 1.
In example 6, the functional admixture is zirconium micro-silica powder, ultra-fine fly ash and corundum powder according to the mass ratio of 50: 15: mixing at a ratio of 35; the fiber is straight steel fiber; the functional auxiliary agent is calcium sulfate, calcium hypophosphite and sodium formate according to the mass ratio of 25: 35: mixing at a ratio of 40; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent is 30: 60: 4: 5: mixing at a ratio of 1.
In example 7, the functional admixture is ultrafine fly ash, glass powder, and corundum powder in an amount of 40: 30: mixing at a ratio of 30; the fiber is straight steel fiber; the functional auxiliary agent is sodium dodecyl sulfate, 3-methyl-1, 5-pentanediol and sodium formate, and the mass ratio is 20: 50: mixing at a ratio of 30; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent to the polyether modified organic silicon type defoaming agent is 80: 15: 3: 1.5: mixing at a ratio of 0.5.
In example 8, the functional admixture is glass powder and corundum powder, and the mass ratio of glass powder to corundum powder is 50: mixing at a ratio of 50; the fiber is polyformaldehyde fiber; the functional auxiliary agent is sodium sulfate, 3-methyl-1, 5-pentanediol, sodium formate, calcium hypophosphite and sodium tripolyphosphate, and the mass ratio of the functional auxiliary agent is 15: 35: 15: 25: mixing at a ratio of 10; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent to the polyether modified organic silicon type defoaming agent is 55: 40: 2.5: 2: mixing at a ratio of 0.5.
In example 9, the functional admixture is zirconium micro-silica powder, ultra-fine fly ash, glass powder, and corundum powder, in an amount of 30: 15: 25: mixing at a ratio of 40; the fiber is polyformaldehyde fiber and straight steel fiber according to the mass ratio of 5: mixing at a ratio of 95; the functional auxiliary agent is sodium sulfate, 3-methyl-1, 5-pentanediol, calcium hypophosphite and sodium tripolyphosphate, and the mass ratio is 25: 30: 30: 15, mixing in proportion; the water reducing agent is a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and polyether modified organic silicon type defoaming agent, and the mass ratio of the water reducing agent is 90: 5: 1.5: 3: mixing at a ratio of 0.5.
Comparative example
TABLE 2 ultra high Performance Cement-based repair materials in respective proportions
Comparative example 1: the functional admixture was ground quartz powder and the other components were the same as in example 1.
Comparative example 2: the other components are the same as in example 1, lacking the functional assistant.
Comparative example 3: the water reducing agent is a common carboxyl high-performance water reducing agent, and other components are the same as those in the example 1.
Comparative example 4: the conventional ultrahigh-performance concrete is prepared by the following steps of mixing, wherein the functional admixture is ground quartz powder, the water reducing agent is a common carboxyl-based high-performance water reducing agent, the functional additive is absent, and other component materials are the same as those in example 1.
The low thixotropic ultra-high performance concrete of examples 1-9 and the ultra-high performance concrete of comparative examples 1-4 were prepared by mixing cement, silica fume, functional admixture, sand and crushed stone for 1min, adding functional adjuvant, water and water reducer mixed in advance, stirring for 6min, and finally adding fiber and stirring for 3 min.
Application examples
Comparative tests of slump expansion, viscosity, setting time and compressive strength were carried out using the ultra-high performance concretes of examples 1 to 9 and comparative examples 1 to 4.
The expansion degree of the ultra-high performance concrete is tested according to a method specified in GB50080-2016 standard of common concrete mixture performance test methods; and (3) during standing expansion degree test, putting the concrete into a slump test barrel, standing for 30min, and lifting the slump test barrel according to the standard to perform expansion degree test. The thixotropy is reflected by the loss of concrete slump after standing, and the smaller the loss of the expansion degree after standing is, the smaller the thixotropy of the concrete is.
The concrete setting time is tested according to the specified method in GB50080-2016 Standard test method for the Performance of common concrete mixtures.
Viscosity of ultra-high performance concrete passing through T50The time is reflected, the test is carried out according to the method specified in CECS 203-2006 technical Specification for application of self-compacting concrete, and the longer the time is, the higher the viscosity of the concrete is.
The compressive strength of the ultra-high performance concrete is tested according to GBT31387-2015 reactive powder concrete.
The test results are as follows:
properties of the Low viscosity Pumping ultra high Performance concretes in the examples of Table 3
TABLE 4 Performance of the ultra high Performance concrete of the comparative examples
From the test results, the ultrahigh-performance concrete prepared by adopting the functional admixture, the functional auxiliary agent and the compounded high-performance water reducing agent and adjusting the fiber dosage, sand, stone and water consumption has higher fluidity and lower thixotropy, and the setting time is not obviously different from that of the common ultrahigh-performance concrete. In addition, the concrete has higher compressive strength, and the compressive strength of the concrete can reach over 160MPa after standard curing for 28 days.
Furthermore, comparing examples 2 and 8 and examples 6 and 7, it can be seen that, although the initial fluidity is slightly lower or the same, the addition of the functional admixture of corundum powder and zircon silica fume is more advantageous for reducing the loss of the standing fluidity, i.e., decreasing the thixotropy of the ultra-high performance concrete; similarly, when a combination of inorganic and organic phosphates of calcium hypophosphite and/or sodium tripolyphosphate and sodium ethylene diamine tetra methyl phosphonate or tetrasodium 2-phosphonate butane-1, 2, 4-tricarboxylate is added to the functional assistant (examples 1, 3 and 4), the loss of fluidity of the ultra-high performance concrete at rest is minimized, i.e., the ultra-high performance concrete has lower thixotropy. In comparative example 1, ground quartz powder was used in place of the functional admixture, and the other components were the same as in example 1, and the performance data shows: the initial fluidity, thixotropy, viscosity and compressive strength of the ultra-high performance concrete are all obviously inferior to those of the concrete in example 1 by adopting the ground quartz powder. The functional admixture can reduce the formation rate of a flocculation structure in concrete and improve the thixotropy; the stacking compactness of the particles is improved, the viscosity of the ultra-high performance concrete is effectively reduced, the compactness of the concrete is improved, and the compressive strength of the concrete is improved.
In comparative example 2, lacking the functional aid and the other components being the same as in example 1, the performance data shows: in the absence of functional auxiliaries, the thixotropy of the concrete is significantly higher than that of example 1. Functional adjuvant reduces early C3The hydration rate of A reduces the formation of early ettringite, reduces the bridging effect of the ettringite on the surfaces of cement and silica fume, reduces the acting force among particles and further reduces the thixotropy of the ultrahigh-performance concrete.
In comparative example 3, a common carboxyl-based high-performance water reducing agent is used, other components are the same as those in example 1, and performance data show that: by adopting the common carboxyl high-performance water reducing agent, the initial fluidity, the thixotropy and the viscosity of the concrete are obviously inferior to those of the concrete in example 1. Based on the selective absorption characteristic of the powder, the compounded high-performance water reducing agent is adopted, so that the water reducing agent can be uniformly adsorbed on the surfaces of all the powder, the uniform and rapid dispersion of various powder in the ultra-high-performance concrete with an extremely low water-to-gel ratio is large, the forming rate of a flocculation structure is reduced, the fluidity of the ultra-high-performance concrete is increased, and the viscosity and thixotropy are reduced.
Comparative example 4 is the conventional ultra-high performance concrete mix proportion, the functional admixture is ground quartz powder, the water reducing agent is a common carboxylic acid high performance water reducing agent, the functional additive is lacked, other component materials are the same as example 1, and the performance data shows that: the low-thixotropy ultrahigh-performance concrete disclosed by the invention not only has initial fluidity obviously superior to that of the common ultrahigh performance, but also has obviously reduced thixotropy and viscosity, and has no obvious difference in setting time. In addition, the compressive strength of the low-thixotropic ultrahigh-performance concrete is also superior to that of the conventional ultrahigh-performance concrete.
Claims (6)
1. The low-thixotropy ultrahigh-performance concrete is characterized by comprising the following components in parts by mass:
400-800 parts of cement, namely cement,
50-300 parts of silica fume,
100-500 parts of a functional admixture,
400-1000 parts of sand,
5 to 240 parts of fiber, and a fiber,
5-20 parts of functional auxiliary agent
10-40 parts of water reducing agent
120-180 parts of water;
the cement is Portland cement or ordinary Portland cement with the strength grade of 42.5 or above, and the average grain diameter is 10-20 mu m;
SiO in the silica fume2The content is more than 90 percent, and the average grain diameter of the silica fume is 0.2-5 mu m;
the functional admixture is formed by mixing corundum powder and any one or more than two of zirconium micro silicon powder, ultrafine fly ash and glass powder; wherein the average grain diameter of the zirconium micro silicon powder is 5-10 mu m, and SiO is2The content is more than 60 percent; the average particle size of the ultrafine fly ash is 5-20 μm; the average grain size of the glass powder is 20-200 mu m; the corundum powder is spherical particles, and the average particle size is 200-800 mu m; the functional admixture at least contains more than 30wt% of corundum powder;
the sand is continuous graded sand with the particle size of 0.075-4.75 mm;
the fibers are synthetic fibers and/or metal fibers; wherein the synthetic fiber is any one of polypropylene fiber, polyvinyl alcohol fiber and polyformaldehyde fiber, the length is 3-20 mm, and the diameter is 40-200 mu m; the metal fiber is steel fiber, the length of the metal fiber is 3-30 mm, and the diameter of the metal fiber is 0.1-0.3 mm;
the functional auxiliary agent is a mixture of any two or more than three of sodium sulfate, calcium sulfate or sodium dodecyl sulfate and 3-methyl-1, 5-pentanediol, sodium formate, calcium hypophosphite, sodium tripolyphosphate, ethylene diamine tetra methyl sodium phosphonate and 2-butane phosphonate-1, 2, 4-tricarboxylic acid tetrasodium; the dosage of sodium sulfate, calcium sulfate or sodium dodecyl sulfate in the functional auxiliary agent is not lower than 15% and not higher than 35%;
the water reducing agent is prepared from a carboxylic acid-based high-performance water reducing agent, a phosphonic acid-based high-performance water reducing agent, lignosulfonate, acrylate and a polyether modified organic silicon type defoaming agent (30-90): (5-60): (2-60): (1.5-5): (0.5-1).
2. The low thixotropic ultra-high performance concrete of claim 1, wherein crushed stone is further added to the low thixotropic ultra-high performance concrete, and the amount of the crushed stone is not more than 800 parts; the broken stone is any one of limestone, granite, diabase and basalt, and the particle size of the broken stone is 4.75-19 mm.
3. The low-thixotropy ultra-high performance concrete according to claim 1, wherein the mass of the zirconium micro silicon powder in said functional admixture accounts for 30-50wt% of the total mass of the functional admixture.
4. The concrete of claim 1, wherein the functional assistant is added with a combination of inorganic phosphate and organic phosphonate of calcium hypophosphite and/or sodium tripolyphosphate and sodium ethylene diamine tetra methyl phosphonate or 2-phosphonic butane-1, 2, 4-tricarboxylic acid tetrasodium, and the dosage ranges of the inorganic phosphate and the organic phosphonate are (1-2): (2-1).
5. The method of preparing a low thixotropic ultra-high performance concrete of claim 1, comprising the steps of: firstly, mixing cement, silica fume, a functional admixture and sand for 0.5-2 min, then adding a functional additive, water and a water reducing agent which are mixed in advance, stirring for 5-10 min, and finally adding fibers, and stirring for 2-4 min to obtain the low-thixotropic ultrahigh-performance concrete.
6. The method of preparing a low thixotropic ultra-high performance concrete of claim 2, comprising the steps of: firstly, mixing cement, silica fume, a functional admixture, sand and broken stones for 0.5-2 min, then adding a functional auxiliary agent, water and a water reducing agent which are mixed in advance, stirring for 5-10 min, and finally adding fibers, and stirring for 2-4 min to obtain the low-thixotropic ultrahigh-performance concrete.
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| CN115893952A (en) * | 2022-12-21 | 2023-04-04 | 中交第二航务工程局有限公司 | Method for preparing ultra-high performance concrete material by using polyformaldehyde fibers |
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