CN113024211B - High-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete and preparation method thereof - Google Patents

High-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete and preparation method thereof Download PDF

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CN113024211B
CN113024211B CN202011010516.6A CN202011010516A CN113024211B CN 113024211 B CN113024211 B CN 113024211B CN 202011010516 A CN202011010516 A CN 202011010516A CN 113024211 B CN113024211 B CN 113024211B
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strength
water
concrete
stirring
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CN113024211A (en
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郑山锁
尚志刚
阮升
王斌
杨建军
郑捷
董立国
郑跃
刘华
李亚辉
温桂峰
杨松
李磊
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Xian University of Architecture and Technology
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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
    • C04B28/14—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 calcium sulfate cements
    • C04B28/141—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 calcium sulfate cements containing dihydrated gypsum before the final hardening step, e.g. forming a dihydrated gypsum product followed by a de- and rehydration step
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28C5/00—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions
    • B28C5/003—Methods for mixing
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    • 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
    • C04B14/022—Carbon
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    • 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
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    • C04B14/38—Fibrous materials; Whiskers
    • C04B14/46—Rock wool ; Ceramic or silicate fibres
    • C04B14/4643—Silicates other than zircon
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    • 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
    • C04B18/06—Combustion residues, e.g. purification products of smoke, fumes or exhaust gases
    • C04B18/08—Flue dust, i.e. fly ash
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    • 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
    • C04B18/06—Combustion residues, e.g. purification products of smoke, fumes or exhaust gases
    • C04B18/10—Burned or pyrolised refuse
    • C04B18/101—Burned rice husks or other burned vegetable material
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    • 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
    • C04B18/14—Waste materials; Refuse from metallurgical processes
    • C04B18/146—Silica fume
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    • 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
    • C04B18/18—Waste materials; Refuse organic
    • C04B18/24—Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper, cork
    • C04B18/248—Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper, cork from specific plants, e.g. hemp fibres
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    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/02—Treatment
    • C04B20/023—Chemical treatment
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    • 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
    • C04B22/12—Acids or salts thereof containing halogen in the anion
    • C04B22/124—Chlorides of ammonium or of the alkali or alkaline earth metals, e.g. calcium chloride
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    • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
    • C04B24/12—Nitrogen containing compounds organic derivatives of hydrazine
    • C04B24/122—Hydroxy amines
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    • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
    • C04B24/24—Macromolecular compounds
    • C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C04B24/2623—Polyvinylalcohols; Polyvinylacetates
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    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/02—Selection of the hardening environment
    • C04B40/0254—Hardening in an enclosed space, e.g. in a flexible container
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    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
    • 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
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Abstract

The invention discloses high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete and a preparation method thereof, wherein the mixing ratio comprises the following components: and (3) cement: sand: broken stone: fly ash: straw ash: silica fume: nano silicon: water: water reducing agent: exciting agent: defoaming agent: shrinkage reducing agent: ramie fiber: basalt fiber: hydroxyl modified single-walled carbon nanotube dispersion: carboxyl modified polyvinyl alcohol polymer = 460-470:710-720:985:75-85:65-70:40-45:3.8-4.4:105-110:14-16:12-13:2.2-2.6:11-12:5.5-5.7:9.8-10.2:25-30:16.5-18. Uniformly mixing the materials at intervals by a layered stirring method, discharging, forming and maintaining. The concrete mechanics of the invention comprises that the bonding performance and the durability of the steel are obviously improved, and the cooperative working capacity with the steel is enhanced.

Description

High-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete and preparation method thereof
Technical Field
The invention belongs to the field of building materials, and relates to concrete with high toughness, high cohesiveness, high durability and high volume stability, which is doped with ramie fibers, basalt fibers, carboxyl modified polyvinyl alcohol polymer, hydroxyl modified single-wall carbon nanotube dispersion liquid, straw ash, fly ash, silica fume and nano silicon, in particular to high-toughness high-cohesiveness C150-strength ultrahigh-strength fiber concrete and a preparation method thereof.
Background
In structural design, considering the demands of using functions, member rigidity and construction convenience, different grade concrete is generally adopted according to different stress conditions so as to meet the compressive strength, bending resistance and splitting tensile strength required by the members when the members are stressed and ensure the bonding strength of the concrete and steel for cooperative work. The concrete materials with different labels have different elastic moduli and different deformation properties, so that excessive or insufficient strength indexes can cause uncoordinated deformation of steel and concrete when the member is stressed, thereby causing that the two materials cannot fully cooperate or a certain material cannot fully exert mechanical properties, and causing material waste. The common concrete and the high-performance concrete materials have poor cracking resistance and large brittleness, and the brittleness characteristics are more obvious along with the improvement of the strength grade of the concrete, and under the condition of high stress or complex stress, concrete with specific high strength grade is often needed to be used, for example, in different reinforced layers of an ultra-high-rise structure, anti-seismic reinforced areas, frame columns (especially corner columns) of a bottom frame shear layer, shear walls and different floors of a giant ultra-high-rise structure, the strength index is small, the cross section of the components is overlarge, the rigidity is overlarge, the fat beam is the column, the structure using function is limited, the rigidity of the components is insufficient or the material is wasted due to the overlarge strength index, and therefore, the concrete with the strength grade of C150 is sometimes needed to be used specifically in consideration of bearing capacity, rigidity requirement, economic benefit, design requirement and the like, and at this time, the brittleness characteristics of the concrete can reduce the anti-seismic bearing capacity of the components and the structure, and even influence the safety and reliability of the components. Meanwhile, with the gradual improvement of the mechanical properties of steel, the toughness, the deformation performance and the bonding performance of common concrete are difficult to meet the synergistic effect between the concrete and the profile steel.
The silica fume has excellent particle size and volcanic ash activity, is an important mineral admixture for preparing high-performance concrete, but has lower annual output in China, only has 3000t-4000t, can only meet the requirement of partial high-performance concrete, and limits the mass use of the silica fume. And the yield of straw per year is more than 7 hundred million t, which is the first place in the world. At present, only a small part of straws are used for power generation of biomass energy power plants, and most of straws are still naturally piled up or burned in the open air, so that resource waste and environmental pollution are caused. Straw ash generated by power generation of a power plant can cause secondary pollution to the environment if the straw ash is not properly developed and utilized. Along with the technological progress, the straw ash prepared by burning corn straw under proper conditions contains about 85 percent of amorphous SiO 2 And a certain amount of active Al 2 O 3 The content of the metal oxide K, na is less, the pozzolan effect and the micro aggregate filling effect can be fully exerted, and the metal oxide can be applied to concrete to improve the mechanical property.
The toughness of concrete and cement-based composite materials is generally improved by adding fibers, and the existing steel fibers and synthetic fibers are difficult to popularize in concrete engineering application due to complex process, high cost and low yield, so that the engineering community gradually starts to search for high-performance plant fibers with rich sources to replace the steel fibers and the synthetic fibers. The ramie fiber has high cellulose content, high strength, high toughness, high pH resistance, green and pollution-free performance, and can effectively replace the application of steel fibers and synthetic fibers in engineering. The method is mainly used for producing the ramie in China, and the yield of the ramie accounts for more than 90% of the world, so that the ramie fibers are convenient to obtain in China, low in price and high in popularization and application value. Meanwhile, because cracks with different sizes exist in the concrete, the optimal toughening effect cannot be achieved by adding single fibers.
The carbon nano tube is a one-dimensional fiber material with nano-scale diameter and micro-scale length, has excellent physical and mechanical properties, has an elastic modulus of about 1TPa, is about 5 times that of steel, and has a density of only 1/6 of that of the steel; the tensile strength of the carbon nano tube can reach 60-150GPa, the compressive strength can reach 100-170GPa, and the fracture strain is 30% -50%. However, the carbon nano tube has complete and smooth surface, few defects and active groups, low relative solubility in water and various solutions or composite materials, large van der Waals force and surface free energy, and easy spontaneous agglomeration or winding, and seriously affects the uniform dispersion of the carbon nano tube in the polymer. The carbon nano tube is divided into a single-wall carbon nano tube and a multi-wall carbon nano tube according to the number of layers, various defects are easily captured between layers when the multi-wall carbon nano tube is formed, and the defects that the tube wall is full of small hole patterns are caused, so that the mechanical property of the multi-wall carbon nano tube is influenced, so that the single-wall carbon nano tube is selected, and is dispersed by using a surfactant and ultrasonic treatment after being modified, and the modified single-wall carbon nano tube dispersion liquid which can be stably dispersed in water is obtained on the basis that the carbon nano tube is not cut off and the mechanical property of the carbon nano tube is not damaged, so that the micro fiber toughening and reinforcing effects of the modified single-wall carbon nano tube can be fully exerted in concrete.
In summary, from the perspective of green environmental protection, cost saving and effective utilization of resources, the adoption of multistage crack control and macroscopic to microscopic particle grading optimization design, and the organic combination of the multistage crack control and the macroscopic to microscopic particle grading optimization design are considered to form a unified whole, so that the improvement and the enhancement of the internal structure of the concrete are realized, and the high-toughness high-cohesiveness ultra-high-strength concrete with the C150 strength grade, higher toughness, high cohesiveness, high durability and better cooperative deformability and capable of cooperating with high-performance steel is prepared to be the technical problem to be solved in the current field.
Disclosure of Invention
The invention aims to provide high-toughness high-cohesiveness C150-strength ultrahigh-strength fiber concrete used in different reinforcement layers, anti-seismic reinforcement areas and frame columns (especially corner columns) of bottom frame shear layers of an ultrahigh-rise structure, shear walls and different floors of a giant ultrahigh-rise structure, and a preparation method thereof.
In order to achieve the above purpose, the technical scheme disclosed by the invention is as follows: the high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete comprises the following raw materials in parts by weight:
460-470 parts of cement, 710-720 parts of sand, 985 parts of crushed stone, 75-85 parts of fly ash, 65-70 parts of straw ash, 40-45 parts of silica fume, 3.8-4.4 parts of nano silicon, 105-110 parts of water, 14-16 parts of water reducer, 12-13 parts of excitant, 2.2-2.6 parts of defoamer, 11-12 parts of shrinkage reducer, 5.5-5.7 parts of ramie fiber, 9.8-10.2 parts of basalt fiber, 16.5-18 parts of carboxyl modified polyvinyl alcohol polymer and 25-30 parts of hydroxyl modified single-wall carbon nanotube dispersion liquid.
The cement is P I62.5R-grade silicate cement, and a cement variety with good compatibility with the polycarboxylic acid water reducer is selected.
The sand adopts river sand with 7:3 mass ratio and hard texture and high-quality quartz sand with good grading, the fineness modulus of the river sand is 2.8-3.0, the silicon dioxide content in the quartz sand is not less than 98%, the grain diameter is 0.3-0.6mm, and the density is 2.62g/cm 3 。
The broken stone is basalt broken stone with good grading, compactness, hardness and rough surface, the broken stone with continuous grain size of 5-10mm and 10-15mm is mixed according to the mass ratio of 7:3, the parent rock strength is not lower than 250MPa, and the maximum grain size is not more than 15mm.
The fly ash adopts high-quality I-grade fly ash of a power plantThe ash has a screen residue of 45 μm square hole screen not more than 10%, water demand ratio not more than 95%, and specific surface area larger than 400m 2 /kg。
The straw ash is prepared by burning stems of mature corn straw at 650-820 deg.C, removing potassium, grinding for 25min with ball mill, and has silicon dioxide content of more than 84.1%, average particle diameter of 6-12 μm, and specific surface area of more than 12m 2 /g。
Further, the potassium removal treatment method comprises the following steps:
1) Placing the straw ash into distilled water for stirring and soaking, then standing, pouring out supernatant, continuously adding distilled water for stirring and soaking, and repeating the process for more than 5 times, wherein the soaking time lasts for one week;
2) Pouring out the supernatant liquid for the last time, heating to 90 ℃ with distilled water, preserving heat for 15-20min, adding distilled water for soaking after preserving heat, and repeating the step 1);
3) Repeating steps 1) and 2) twice in sequence;
4) Finally, the temperature is kept at 60 ℃ for 2 hours, and the supernatant is poured out and dried for standby.
The silica fume has silica content greater than 93%, volcanic ash activity index greater than 95%, average particle size of 0.1-0.15 μm, and specific surface area greater than 25m 2 /g。
The nano silicon is high-purity nano silicon dioxide prepared by a gas phase method, the purity is more than 99%, the average particle size is 10nm-40nm, and the specific surface area is more than 130m 2 /g。
The water reducer is a polycarboxylic acid high-performance water reducer suitable for a cementing material system with low water-cement ratio and high silica fume content, the solid content is 20%, the water reducing rate is more than 35%, and the compression strength of concrete is not adversely affected.
The shrinkage reducing agent is SU-SRA type shrinkage reducing agent.
The defoaming agent is a Liqi X-2756 efficient concrete defoaming agent.
The exciting agent is an organic-inorganic composite exciting agent, and the composite exciting agent is prepared by compounding the following raw materials in percentage by mass:
50-58% of dihydrate gypsum, 40-48% of calcium chloride and 1.5-2% of triethanolamine.
The ramie fiber is refined dry ramie fiber after alkali treatment and drying, the length is 40-50mm, the diameter is 30-40 mu m, the tensile strength is more than or equal to 1000MPa, the elastic modulus is more than or equal to 11.4GPa, the breaking elongation is 8.9%, and the specific gravity is 1.54-1.55g/cm 3 Has good hydrophilicity, high bond strength and acid and alkali resistance.
The basalt fiber has a length of 12mm, a diameter of 7-15 μm, a tensile strength of not less than 3000MPa, an elastic modulus of not less than 91GPa and a specific gravity of 2.63-2.65g/cm 3 。
The hydroxyl modified single-walled carbon nanotube dispersion liquid is prepared by the following method:
1) Adding 2 parts of single-wall carbon nanotubes into 120 parts of NaOH aqueous solution with the concentration of 3.0-5.0M according to the parts by weight, carrying out ultrasonic treatment for 15-20min, and stirring; sealing the carbon nanotube dispersion liquid at high pressure, and reacting for 180min at 200-260 ℃; cooling to room temperature, centrifugally separating, adding deionized water for dilution, and removing supernatant; then carrying out ultrasonic treatment for 20min, stirring, filtering by using a hydrophilic polytetrafluoroethylene filter membrane, and washing the obtained solid product to be neutral; drying for 12 hours at 40 ℃ to obtain the modified single-walled carbon nanotube with the surface containing hydroxyl oxygen-containing functional groups;
2) Dispersing 1 part of surfactant polyethylene glycol octyl phenyl ether and 2 parts of modified single-walled carbon nanotube into 98 parts of deionized water in turn, stirring to ensure that the modified single-walled carbon nanotube is completely soaked by surfactant aqueous solution, carrying out ultrasonic treatment for 30min, and centrifuging and settling the dispersion;
3) The upper layer liquid is filtered by 500 meshes of filter cloth to obtain carbon nano tube dispersion liquid 1; carrying out ultrasonic treatment on the liquid with the precipitation agglomerated carbon nano tubes at the bottom for 60min again to obtain carbon nano tube dispersion liquid 2, wherein the carbon nano tube dispersion liquid is hydroxyl modified single-wall carbon nano tube dispersion liquid twice;
the average pipe diameter of the single-wall carbon nano-tube is 1-2nm, the length is 10-20 mu m, and the purity is more than or equal to 98.
The carboxyl modified polyvinyl alcohol polymer is an organic polymer obtained by uniformly mixing carboxyl modified polyvinyl alcohol, water and an auxiliary agent, and comprises the following raw materials in percentage by mass:
36-39% of carboxyl modified polyvinyl alcohol, 60-63% of water and 1-1.5% of auxiliary agent;
further, the carboxyl modified polyvinyl alcohol has a degree of polymerization of 2400, an alcoholysis degree of 99%, a carboxyl/hydroxyl molar ratio of 3/97, and a ph=7.
Further, the auxiliary agent is polyacrylate defoamer.
Further, the mixing and homogenizing method comprises the following steps: placing carboxyl modified polyvinyl alcohol into water, standing for 30min at normal temperature to fully swell, then placing into a constant temperature water tank at 95 ℃ for heating and dissolving, adding an auxiliary agent, continuously stirring until a uniform transparent solution is formed, and preserving heat for later use.
The invention also discloses a preparation method of the high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete, which comprises the following steps:
1) Adding 14-16 parts by mass of water reducer and 25-30 parts by mass of hydroxyl modified single-wall carbon nanotube dispersion liquid into two-thirds of the total water, and marking as a mixed solution 1; adding 11-12 parts of weighed shrinkage reducing agent and 2.2-2.6 parts of defoamer into one third of water with total water content, marking as mixed solution 2, and preparing 16.5-18 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water content is 105-110 parts;
2) Dividing 5.5-5.7 parts of ramie fibers, 985 parts of broken stone, 710-720 parts of sand, 460-470 parts of cement, 75-85 parts of fly ash, 65-70 parts of straw ash, 40-45 parts of silica fume, 3.8-4.4 parts of nano silicon and 9.8-10.2 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of broken stone, sand, cement, fly ash, straw ash, silica fume and nano silicon in the disc mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 16.5-18 parts of prepared carboxyl modified polyvinyl alcohol polymer, and stirring for 2min;
6) Adding 12-13 parts of exciting agent into the disc mixer, and uniformly stirring for 2-3min;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method obtained by the preparation method comprises the following steps:
standard curing: pouring the concrete mixture into a cast iron mold for molding and compaction, standing for 1d-2d in a standard curing chamber with the temperature of 20+/-2 ℃ and the relative humidity of more than or equal to 95%, removing the mold, and curing in the standard curing chamber to the required age.
The invention aims to solve the problems of high brittleness, low toughness, poor durability, poor bonding performance with section steel and the like of common concrete, and utilizes the easily obtained materials in the market, adopts an improved concrete layering stirring process, considers the dosage proportion of each cementing material required by specific concrete strength grade and the quantity and size distribution of cracks in a cement matrix under corresponding proportion, and is based on multi-scale crack grading control and continuous grain grading design of the cementing material. The ramie fiber with water storage function and toughening function is adopted, the ramie fiber can play an internal curing function in the hydration process of concrete, the hydration process of a cementing material can be promoted, meanwhile, basalt fiber and hydroxyl modified single-wall carbon nano tubes are matched, carboxyl modified polyvinyl alcohol polymer is used for filling holes, and the three fibers are mutually bonded to form an organic whole, so that cracks with different dimensions in the concrete are bridged, the development of the cracks is effectively restrained, and the toughness of the concrete is enhanced; at the same time, carboxyl modified polyvinyl alcohol is polymerized The product can also encapsulate hydration products, which react more fully, and carboxyl groups contained in the hydration products react with Ca 2+ And an ionic bond is generated, and hydroxyl contained in the ionic bond forms a hydrogen bond with oxygen in a silicon-oxygen hydration product, and the ionic bond is crosslinked with the hydration product, so that the pores are effectively filled, and the structure is more compact. In addition, mineral admixtures with different particle sizes, including fly ash, straw ash, silica fume and nano-scale nano silicon dioxide, are added into the concrete, so that on one hand, continuous particle grading is formed among cementing materials, the micro aggregate filling effect of the cementing materials can be effectively exerted, on the other hand, the mineral admixtures can exert pozzolanic effect and super-superposition effect, improve hydration products of the concrete, reduce pore size, reduce harmful pore number and improve compactness of the concrete, and under the combined action of the two aspects, the bonding interface between the concrete and the profile steel is more compact, the bonding force is further improved along with the improvement of the form of the hydration products, and meanwhile, the bond between a concrete matrix and the fiber material is enhanced, so that each fiber can be synergistically acted, the toughness of the concrete is further improved, and Cl can be effectively reduced - 、SO 4 2- 、CO 2 And harmful ions such as ions invade, so that the durability of the concrete is improved. According to the invention, through the synergistic effect of the components, the pore structure of the concrete is improved, so that the internal structure of the concrete is more compact, the hydration shrinkage of the concrete and the development of cracks with different dimensions under the stress state are targeted inhibited, and finally, the novel fiber concrete material with high toughness, high bonding performance, high strength and high durability is prepared.
Compared with the prior art, the invention has the beneficial effects that:
1) The ramie fiber used in the invention is long fiber with 40-50mm, has the characteristics of high tensile strength, high elastic modulus and high toughness, and can effectively inhibit the formation and development of macroscopic cracks of concrete in a complex stress state; the natural hydrophilicity of the ramie fibers enables the surface of the ramie fibers to have strong bond strength, good bonding capability with a cement matrix, and enough anchoring length of the long fibers, so that the ramie fibers can be effectively prevented from being pulled out when the concrete cracks, further development of the cracks is prevented, and the deformation capability and the energy consumption capability of the concrete can be increased due to the bridging effect of the fibers; in addition, the ramie fiber has a unique fiber cavity structure and a huge specific surface area, and the cavity structure can store partial moisture, so that an internal curing effect is achieved, and the hydration process of concrete is promoted. Therefore, the ramie fiber can improve the mechanical property of the concrete and the durability such as crack resistance, permeability resistance, freeze thawing resistance and the like.
2) The basalt fiber and the hydroxyl modified single-wall carbon nanotube used in the invention have the characteristics of high strength and high elastic modulus, wherein the single-wall carbon nanotube is modified, and is dispersed by using a surfactant and ultrasonic treatment, so that the hydroxyl modified single-wall carbon nanotube which can be stably and uniformly dispersed in water is obtained on the basis of not cutting off the carbon nanotube and not damaging the mechanical property of the carbon nanotube, the nano-size effect and the surface effect of the hydroxyl modified single-wall carbon nanotube are used as nano-level fibers to play a bridging role, the occurrence and development of nano-level cracks are controlled, and the strength of a cement matrix material is increased; the lengths of the basalt fibers and the hydroxyl modified single-wall carbon nanotubes are respectively 12mm and 10-20 mu m, so that the formation and development of cracks caused by factors such as plastic shrinkage, temperature change and the like of the concrete can be effectively inhibited, the basalt fibers and the hydroxyl modified single-wall carbon nanotubes cooperate with ramie fibers to play a bridging role, the development of cracks with different scales in the concrete is controlled in a grading manner, and the strength, toughness, deformation performance and durability of the concrete can be effectively improved; the carboxyl modified polyvinyl alcohol polymer is added, a large amount of surface active substances in the polymer can increase the wetting effect of the aggregate surface, improve the bonding capability between the aggregate and a matrix, and simultaneously, the polymer forms a film to wrap hydration products and unhydrated particles in the concrete to form a space three-dimensional continuous network structure, so that microcracks among the matrixes are reduced, the network structure of the polymer is mutually connected with three fibers to jointly form a more dense space three-dimensional network structure, the toughness of the concrete and the bonding performance of the concrete and profile steel are improved, and further, the polymer and a cementing material have a certain degree of chemical reaction, so that the crosslinking of the polymer and the hydration products is enhanced, the bond strength of the matrix to the fibers is also enhanced, the fibers are prevented from being pulled out when the concrete is cracked, and the crack is further prevented from developing; in addition, when the invention is used for a steel reinforced concrete composite structure, three fibers and polymers are uniformly dispersed in concrete to form a space three-dimensional net structure, so that crack development of surrounding concrete is effectively restrained when steel is stressed, a circular restraint effect is formed on the steel, friction force and mechanical biting force between the steel and the concrete are effectively improved, and further, bonding force between the concrete and the steel is enhanced, so that the concrete and the steel can work cooperatively well.
3) The invention takes into consideration that the potassium ions in straw crops are mainly enriched in new leaves and spores, the content of the mature stems is lower, the potassium ion content of different types of straw crops is different, the mature stems of corn straw with low potassium ion content are selected to burn at a certain temperature, then the corn straw is subjected to potassium and sodium removal treatment in a simple and feasible potassium removal mode with low cost, alkali aggregate reaction in concrete can be effectively prevented, the straw ash obtained by grinding after the potassium removal treatment contains more than 84.1 percent of silicon dioxide and a certain amount of active Al and Fe oxides, the volcanic ash activity is higher, the particles of the straw ash are tiny (the average particle diameter is 6-12 mu m), and the porous and net channel structure in the straw ash particles enable the straw ash particles to have larger specific surface area and reach 12m 2 And/g. The straw ash is doped, so that the cementing material particles are more uniform, the gradation is good, the filling compaction effect can be achieved, and the cohesiveness of the concrete is further improved; in addition, because the straw ash has volcanic ash activity similar to that of the silica fume, the straw ash can replace part of the silica fume and can be used for Ca (OH) in a concrete system 2 The reaction generates compact and hard hydrated calcium sulfoaluminate and more stable C-S-H gel, and improves the flexural strength, compressive strength, splitting tensile strength and durability of the concrete; finally, the straw ash is used as agricultural waste, and the treated straw ash is used as a building material to replace part of cement, so that CO in the straw burning and cement production process can be reduced 2 The discharge amount is reduced, so that the cost of concrete is reduced, the reutilization of agricultural wastes is realized, and the purposes of energy conservation and environmental protection are achieved.
4) The fly ash, straw ash, silica fume, nano silicon dioxide and cement mixed in the invention have different particle size ranges to form more continuous grain composition of the cementing material,the filling effect of the micro aggregate can be better exerted, meanwhile, the super-superposition effect is generated by the fly ash, the straw ash, the silica fume and the nano silicon, the hydration of the cementing material is further promoted, more hydration products are converted into C-S-H gel, the pore structure and the cohesiveness of the concrete are improved, in addition, the nano silicon dioxide can enter into more tiny pores, and the surface of the nano silicon dioxide has more unsaturated bonds and larger surface energy, so that the hydration products, especially Ca (OH), are formed 2 The C-S-H gel is quickly gathered on the surface of the cement matrix to react, so that the C-S-H gel is promoted to grow by taking the C-S-H gel as a core, the generation of harmful crystals is limited, the interface structure of the cement matrix is strengthened, and the flexural strength, the compressive strength, the splitting tensile strength, the toughness, the bonding performance and the durability of the concrete are further improved.
5) The shrinkage reducing agent used in the invention can reduce the surface tension of water in the capillary holes of the concrete, compact the concrete structure, further control the shrinkage of the concrete mass, the plastic shrinkage at early hardening and the like, further improve the crack resistance and the permeability resistance of the concrete, and strengthen the durability of the concrete.
6) The exciting agent adopts an organic-inorganic composite exciting agent, and the exciting agent plays a role in jointly exciting by the dihydrate gypsum, the calcium chloride and the triethanolamine, so that ettringite is promoted to be generated, the concrete doped with the fly ash, the silica fume, the nano silicon dioxide and the straw ash has certain micro-expansibility, and the shrinkage performance of the concrete is improved. The glass body reticular structure on the surface of the fly ash is depolymerized by the composite excitant, so that the potential activity of the fly ash is excited, the corrosion effect of the glass body with the three-dimensional space structure taking aluminosilicate as a main hydration component in the fly ash hydration process can be enhanced, the power of forward hydration reaction is improved, more C-S-H gel, hydrated calcium aluminate and other crystals are generated, and the fly ash is promoted to participate in early hydration process. The excitation effect of the dihydrate gypsum on the mineral admixture is shown as follows: SO (SO) 4- Gel with the surface of fly ash particles and AlO dissolved in liquid phase 2- Reacting to generate hydrated calcium sulfoaluminate AFt; in addition, SO 4 2- Can also replace part of SiO in the hydrated calcium silicate 2 2- Displaced SiO 2 2- At the outer layer with Ca 2+ The calcium silicate hydrate is generated by the action, the activity of the fly ash is continuously excited, and Ca is provided by the calcium silicate hydrate 2+ SiO in fly ash, silica fume, nano silicon dioxide and straw ash 2 、Fe 2 O 3 、Al 2 O 3 And reacting to generate hydrated calcium silicate, hydrated calcium ferrite, hydrated calcium aluminate and the like. The excitation of calcium chloride to mineral admixture is mainly achieved by increasing Ca in hydration system 2+ The concentration, the formation of the hydrated chloroaluminate gel phase and the hydrated calcium aluminate are realized, besides, the calcium chloride as a strong electrolyte can also supplement Ca required by the reaction of silica fume, straw ash and nano silicon dioxide in the process of exciting the activity of the fly ash by sulfate 2+ . As an organic fly ash activity excitant, triethanolamine can complex Fe and Al phases in fly ash and the like in the hydration process, promote corrosion of the surfaces of fly ash particles and further hydrate active substances in the fly ash. The synergistic effect among the dihydrate gypsum, the calcium chloride and the triethanolamine can fully excite the activity of the mineral admixture, accelerate the hydration rate of the cementing material in the system, promote the generation of hydration products, further improve the strength, the durability and the like of the concrete.
7) The invention adopts a layered stirring method, and determines the particle size of the maximum broken stone particles through experiments, so that long fibers and aggregates can be dispersed uniformly to the greatest extent, the mutual interference of the long fibers and coarse aggregates is avoided, the aggregation of the fibers is avoided, and larger holes are generated in a cement matrix, and even the honeycomb pitting surface phenomenon is caused.
The measures can effectively improve the compressive strength, toughness, deformability, durability and the like of the concrete, and enhance the bonding strength and the collaborative deformability between the concrete and the profile steel. The high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete prepared by the method provided by the invention has the advantages that various cementing materials with different particle diameters in the concrete are uniformly distributed, the particle size is uniformly distributed from large to small, the micro aggregate filling effect of each cementing material is fully exerted, hydration products of the cementing materials can be stacked and compacted, the pore structure of the concrete is further improved, and meanwhile, the multi-scale fibers are uniformly dispersed, so that the high-cohesiveness C150 strength ultrahigh-strength fiber concrete is prepared by the method provided by the invention, and the high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete is prepared by the method provided by the inventionThe concrete has higher toughness and excellent durability, has better bonding performance with the section steel, further improves the deformability and enhances the synergy with the section steel. The fiber concrete has 28d cube compressive strength not less than 152.65MPa, flexural strength not less than 38.36MPa, splitting tensile strength not less than 16.98MPa, bonding strength with section steel not less than 8.06MPa, and chloride ion migration coefficient not greater than 15X10 -14 m 2 And/s. The high-performance fiber concrete with high volume stability, high durability and high toughness is prepared by the invention, the raw materials are easy to obtain, the preparation process is simple, the application and popularization requirements of sustainable development and modern green building materials are met, and the high-performance fiber concrete material is a novel green and environment-friendly high-performance fiber concrete material.
Detailed Description
The present invention is further described in the following with reference to specific embodiments, using examples, to make the advantages of the present invention more easily understood by those skilled in the art, but not to limit the scope of the present invention.
The invention relates to high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete, which is prepared by the following method:
1) Adding 14-16 parts by mass of water reducer and 25-30 parts by mass of hydroxyl modified single-wall carbon nanotube dispersion liquid into two-thirds of the total water, and marking as a mixed solution 1; adding 11-12 parts of weighed shrinkage reducing agent and 2.2-2.6 parts of defoamer into one third of water with total water content, marking as mixed solution 2, and preparing 16.5-18 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water content is 105-110 parts;
2) Dividing 5.5-5.7 parts of ramie fibers, 985 parts of broken stone, 710-720 parts of sand, 460-470 parts of cement, 75-85 parts of fly ash, 65-70 parts of straw ash, 40-45 parts of silica fume, 3.8-4.4 parts of nano silicon and 9.8-10.2 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of broken stone, sand, cement, fly ash, straw ash, silica fume and nano silicon in the disc mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 16.5-18 parts of prepared carboxyl modified polyvinyl alcohol polymer, and stirring for 2min;
6) Adding 12-13 parts of exciting agent into the disc mixer, and uniformly stirring for 2-3min;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete forming and curing method in the invention comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibrating table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod so as to discharge redundant bubbles in the concrete mixture; after molding, placing the test block in an environment with the temperature of 20+/-2 ℃, covering the surface of the test block with wetted geotextile, standing for 1d, removing the mold, and curing in a standard curing room with the temperature of 20+/-2 ℃ and the relative humidity of more than or equal to 95% until the required age.
Wherein:
the cement is commercial P I62.5R-grade silicate cement, and has good compatibility with the polycarboxylic acid water reducer.
The sand adopts river sand with 7:3 mass ratio and hard texture and high-quality quartz sand with good grading, the fineness modulus of the river sand is 2.8-3.0, the silicon dioxide content in the quartz sand is not less than 98%, the grain diameter is 0.3-0.6mm, and the density is 2.62g/cm 3 。
The used broken stone is basalt broken stone with good grading, compactness, hardness and rough surface, the broken stone with continuous grain size of 5-10mm and 10-15mm is mixed according to the mass ratio of 7:3, the parent rock strength is not lower than 250MPa, and the maximum grain size is not more than 15mm.
The fly ash is high-quality class I fly ash of a power plant, the screen residue of a square-hole sieve with 0.045mm is not more than 10%, and the specific surface area is more than 400m 2 Per kg, the average particle diameter is in the range of 10-30. Mu.m.
The straw ash is prepared by burning stems of mature corn straw at 650-820 deg.C, removing potassium, grinding for 25min with ball mill, and has silicon dioxide content of more than 84.1%, average particle diameter of 6-12 μm, and specific surface area of more than 12m 2 /g。
The potassium removing treatment method comprises the following steps:
1) Placing the straw ash into distilled water for stirring and soaking, then standing, pouring out supernatant, continuously adding distilled water for stirring and soaking, and repeating the process for more than 5 times, wherein the soaking time lasts for one week;
2) Pouring out the supernatant liquid for the last time, heating to 90 ℃ with distilled water, preserving heat for 15-20min, adding distilled water for soaking after preserving heat, and repeating the step 1);
3) Repeating steps 1) and 2) twice in sequence;
4) Finally, the temperature is kept at 60 ℃ for 2 hours, and the supernatant is replaced by distilled water and dried for later use.
The silica fume has silica content greater than 93%, volcanic ash activity index greater than 95%, average particle size of 0.1-0.15 μm, and specific surface area greater than 25m 2 /g。
The nano silicon is high-purity nano silicon dioxide prepared by gas phase method, the purity is more than 99%, the average grain diameter is 10nm-40nm, and the specific surface area is more than 130m 2 /g。
The water reducer is a polycarboxylic acid high-performance water reducer which is suitable for a cementing material system with low water-cement ratio and high silica fume content, the solid content is 20%, the pH value is 8.0, the water reducing rate is more than 35%, and the compression strength of the concrete is not affected.
The shrinkage reducing agent is SU-SRA type shrinkage reducing agent.
The defoaming agent is a Liqi X-2756 efficient concrete defoaming agent.
The exciting agent is an organic-inorganic composite exciting agent, and the composite exciting agent is prepared by compounding the following raw materials in percentage by mass: 50-58% of dihydrate gypsum, 40-48% of calcium chloride and 1.5-2% of triethanolamine.
The ramie fiber is refined dry ramie fiber after alkali treatment and drying, the length is 40-50mm, the diameter is 30-40 μm, the tensile strength is more than or equal to 1000MPa, the elastic modulus is more than or equal to 11.4GPa, the breaking elongation is 8.9%, and the specific gravity is 1.54-1.55g/cm 3 。
The length of basalt fiber is 12mm, the diameter is 7 μm-15 μm, the tensile strength is more than or equal to 3000MPa, the elastic modulus is more than or equal to 91GPa, and the specific gravity is 2.63-2.65g/cm 3 。
The hydroxyl modified single-walled carbon nanotube dispersion is prepared by the following method:
1) Preparing NaOH aqueous solution with the concentration of 3.0-5.0M, weighing 2 parts of single-walled carbon nanotubes, adding the single-walled carbon nanotubes into 120 parts of prepared NaOH aqueous solution, and carrying out ultrasonic treatment for 10-20min; pouring the carbon nano tube dispersion liquid into a high-pressure reaction kettle, and reacting for 180min at 200-260 ℃ after sealing; cooling to room temperature, centrifuging at 2200r/min for 30min, adding deionized water for dilution, removing clear liquid, and repeating the dilution to remove clear liquid twice; then ultrasonic treatment is carried out for 20min, stirring is carried out, a hydrophilic polytetrafluoroethylene filter membrane with the filter pore diameter of 0.1 μm is used for filtering, and the obtained solid product is washed with water until the pH value is=7; drying for 12 hours in a vacuum oven at 40 ℃ to obtain the modified single-walled carbon nanotube with the surface containing hydroxyl and oxygen functional groups;
2) Weighing 2 parts of modified single-wall carbon nanotubes with hydroxyl-containing and oxygen-containing functional groups on the surfaces, 1 part of surfactant and 98 parts of deionized water, dispersing the surfactant and the modified single-wall carbon nanotubes into deionized water in sequence, and stirring to ensure that the carbon nanotubes are completely soaked by a surfactant aqueous solution; performing ultrasonic treatment for 30min; then carrying out centrifugal sedimentation on the dispersion liquid, wherein the centrifugal rotating speed is 2200r/min, and the centrifugal time is 30min;
3) The upper layer liquid is filtered by 500 meshes of filter cloth to obtain carbon nano tube dispersion liquid 1; and carrying out ultrasonic treatment on the liquid with the precipitation agglomerated carbon nano tubes at the bottom for 60min again to obtain carbon nano tube dispersion liquid 2, wherein the hydroxyl modified single-wall carbon nano tubes in the carbon nano tube dispersion liquid 1 and 2 can be uniformly and stably dispersed in water.
Wherein the average pipe diameter of the single-wall carbon nano-tube is 1-2nm, the length is 10-20 mu m, and the purity is more than or equal to 98%; the surfactant is polyethylene glycol octyl phenyl ether.
The carboxyl modified polyvinyl alcohol polymer is an organic polymer obtained by uniformly mixing carboxyl modified polyvinyl alcohol, water and an auxiliary agent, and comprises the following raw materials in percentage by mass:
36-39% of carboxyl modified polyvinyl alcohol, 60-63% of water and 1-1.5% of auxiliary agent.
The carboxyl modified polyvinyl alcohol has a polymerization degree of 2400, an alcoholysis degree of 99%, a carboxyl/hydroxyl molar ratio of 3/97 and a ph=7; the auxiliary agent is polyacrylate defoamer.
The mixing method comprises the following steps: placing carboxyl modified polyvinyl alcohol into water, standing for 30min at normal temperature to fully swell, then placing into a constant temperature water tank at 95 ℃ for heating and dissolving, adding an auxiliary agent, continuously stirring until a uniform transparent solution is formed, and preserving heat for later use.
Specific examples are given below to further illustrate the preparation process of the present invention.
Example 1
1) Adding 14 parts by weight of water reducer and 25 parts by weight of hydroxyl modified single-walled carbon nanotube dispersion liquid into two thirds of the total water, and marking as a mixed solution 1; adding 11 parts of weighed shrinkage reducing agent and 2.4 parts of defoamer into one third of the total water, marking as mixed solution 2, and preparing 16.5 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water is 105 parts; wherein the carboxyl modified polyvinyl alcohol polymer is prepared from the following raw materials in percentage by mass: 38.5% of carboxyl modified polyvinyl alcohol, 60% of water and 1.5% of polyacrylate defoamer;
2) Dividing 5.5 parts of ramie fibers, 985 parts of broken stone, 715 parts of sand, 460 parts of cement, 75 parts of fly ash, 70 parts of straw ash, 40 parts of silica fume, 3.8 parts of nano-silica and 9.8 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of broken stone, sand, cement, fly ash, straw ash, silica fume and nano-silica in the disc mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 16.5 parts of prepared carboxyl modified polyvinyl alcohol polymer and stirring for 2min;
6) Adding 12 parts of exciting agent into a disc stirrer, and uniformly stirring for 2-3min; wherein the excitant is prepared by compounding the following raw materials in percentage by mass: 58% of dihydrate gypsum, 40% of calcium chloride and 1.5% of triethanolamine;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method in this embodiment is as follows:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibrating table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod so as to discharge redundant bubbles in the concrete mixture; after molding, placing the test block in an environment with the temperature of 20+/-2 ℃, covering the surface of the test block with wetted geotextile, standing for 1d, removing the mold, and curing in a standard curing room with the temperature of 20+/-2 ℃ and the relative humidity of more than or equal to 95% until the required age.
Example 2
1) Adding 15 parts by weight of water reducer and 27 parts by weight of hydroxyl modified single-walled carbon nanotube dispersion liquid into two thirds of the total water, and marking as a mixed solution 1; adding 12 parts of weighed shrinkage reducing agent and 2.2 parts of defoamer into one third of the total water, marking as mixed solution 2, and preparing 18 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water is 110 parts; wherein the carboxyl modified polyvinyl alcohol polymer is prepared from the following raw materials in percentage by mass: 39% of carboxyl modified polyvinyl alcohol, 60% of water and 1% of polyacrylate defoamer;
2) Dividing 5.6 parts of ramie fibers, 985 parts of crushed stone, 710 parts of sand, 465 parts of cement, 80 parts of fly ash, 65 parts of straw ash, 43 parts of silica fume, 4.4 parts of nano-silica and 10 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of crushed stone, sand, cement, fly ash, straw ash, silica fume and nano-silica in the disc mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 18 parts of prepared carboxyl modified polyvinyl alcohol polymer and stirring for 2min;
6) Adding 12.3 parts of exciting agent into the disc mixer, and uniformly stirring for 2-3min; wherein the excitant is prepared by compounding the following raw materials in percentage by mass: 54.5% of dihydrate gypsum, 43.7% of calcium chloride and 1.8% of triethanolamine;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method in this example was the same as in example 1.
Example 3
1) Adding 14 parts by weight of water reducer and 30 parts by weight of hydroxyl modified single-walled carbon nanotube dispersion liquid into two thirds of the total water, and marking as a mixed solution 1; adding 11.5 parts of weighed shrinkage reducing agent and 2.6 parts of defoamer into one third of the total water, marking as mixed solution 2, and preparing 16.5 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water is 110 parts; wherein the carboxyl modified polyvinyl alcohol polymer is prepared from the following raw materials in percentage by mass: carboxyl modified polyvinyl alcohol 37%, water 62%, polyacrylate defoamer 1%;
2) Dividing 5.6 parts of ramie fibers, 985 parts of crushed stone, 715 parts of sand, 470 parts of cement, 85 parts of fly ash, 68 parts of straw ash, 40 parts of silica fume, 4.4 parts of nano-silica and 10 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of crushed stone, sand, cement, fly ash, straw ash, silica fume and nano-silica in the disc mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 16.5 parts of prepared carboxyl modified polyvinyl alcohol polymer and stirring for 2min;
6) 13 parts of exciting agent is added into the disc mixer and evenly stirred for 2-3min; wherein the excitant is prepared by compounding the following raw materials in percentage by mass: 54% of dihydrate gypsum, 44% of calcium chloride and 2% of triethanolamine;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method in this example was the same as in example 1.
Example 4
1) Adding 15.5 parts by mass of water reducer and 28 parts by mass of hydroxyl modified single-wall carbon nanotube dispersion liquid into two-thirds of the total water, and marking as a mixed solution 1; adding 12 parts of weighed shrinkage reducing agent and 2.4 parts of defoamer into one third of the total water, marking as mixed solution 2, and preparing 17 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water is 105 parts; wherein the carboxyl modified polyvinyl alcohol polymer is prepared from the following raw materials in percentage by mass: 38.6% of carboxyl modified polyvinyl alcohol, 60.4% of water and 1% of polyacrylate defoamer;
2) Dividing 5.7 parts of ramie fibers, 985 parts of broken stone, 715 parts of sand, 460 parts of cement, 80 parts of fly ash, 70 parts of straw ash, 45 parts of silica fume, 4 parts of nano-silica and 10.1 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of broken stone, sand, cement, fly ash, straw ash, silica fume and nano-silica in the mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 17 parts of prepared carboxyl modified polyvinyl alcohol polymer and stirring for 2min;
6) Adding 12.9 parts of exciting agent into the disc mixer, and uniformly stirring for 2-3min; wherein the excitant is prepared by compounding the following raw materials in percentage by mass: 55.2% of dihydrate gypsum, 43% of calcium chloride and 1.8% of triethanolamine;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method in this example was the same as in example 1.
Example 5
1) Adding 15 parts by weight of water reducer and 25 parts by weight of hydroxyl modified single-walled carbon nanotube dispersion liquid into two thirds of the total water, and marking as a mixed solution 1; adding 11.5 parts of weighed shrinkage reducing agent and 2.4 parts of defoamer into one third of the total water, marking as mixed solution 2, and preparing 18 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water is 108 parts; wherein the carboxyl modified polyvinyl alcohol polymer is prepared from the following raw materials in percentage by mass: carboxyl modified polyvinyl alcohol 37.6%, water 61%, polyacrylate defoamer 1.4%;
2) Dividing 5.6 parts of ramie fibers, 985 parts of crushed stone, 710 parts of sand, 465 parts of cement, 75 parts of fly ash, 70 parts of straw ash, 43 parts of silica fume, 4.1 parts of nano-silica and 10.1 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of crushed stone, sand, cement, fly ash, straw ash, silica fume and nano-silica in the disc mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 18 parts of prepared carboxyl modified polyvinyl alcohol polymer and stirring for 2min;
6) Adding 12 parts of exciting agent into a disc stirrer, and uniformly stirring for 2-3min; wherein the excitant is prepared by compounding the following raw materials in percentage by mass: 54% of dihydrate gypsum, 44.5% of calcium chloride and 1.5% of triethanolamine;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method in this example was the same as in example 1.
Example 6
1) Adding 16 parts by weight of water reducer and 30 parts by weight of hydroxyl modified single-wall carbon nanotube dispersion liquid into two thirds of the total water, and marking as a mixed solution 1; adding 12 parts of weighed shrinkage reducing agent and 2.2 parts of defoamer into one third of the total water, marking as mixed solution 2, and preparing 16.5 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water is 110 parts; wherein the carboxyl modified polyvinyl alcohol polymer is prepared from the following raw materials in percentage by mass: 36% of carboxyl modified polyvinyl alcohol, 62.5% of water and 1.5% of polyacrylate defoamer;
2) Dividing 5.7 parts of ramie fibers, 985 parts of broken stone, 720 parts of sand, 470 parts of cement, 85 parts of fly ash, 65 parts of straw ash, 45 parts of silica fume, 4.4 parts of nano-silica and 10.2 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of broken stone, sand, cement, fly ash, straw ash, silica fume and nano-silica in the mixer for stirring for 1min;
3) Adding the other two parts of materials into a stirrer in the same way, and uniformly stirring;
4) Adding the mixed solution 1 in the step 1) into a stirrer, and uniformly stirring for 2-3min;
5) Adding 16.5 parts of prepared carboxyl modified polyvinyl alcohol polymer and stirring for 2min;
6) Adding 13 parts of exciting agent into the stirrer, and uniformly stirring for 2-3min; wherein the excitant is prepared by compounding the following raw materials in percentage by mass: 50% of dihydrate gypsum, 48% of calcium chloride and 2% of triethanolamine;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a stirrer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method in this example was the same as in example 1.
The following comparative examples are given to further illustrate the effects of the present invention in comparison with the examples of the present invention.
Comparative example: the ultra-high strength concrete is ultra-high strength concrete which does not adopt a gel particle continuous grading design, does not mix with fibers, does not mix with carboxyl modified polyvinyl alcohol polymer and hydroxyl modified single-wall carbon nano tube dispersion liquid and adopts a single activator.
The mixture ratio is as follows: 500 parts of cement, 700 parts of sand, 985 parts of crushed stone, 75 parts of fly ash, 55 parts of silica fume, 140 parts of water, 13 parts of water reducer, 12 parts of excitant and 2 parts of defoamer.
The preparation method comprises the following steps:
1) Adding 13 parts by weight of water reducer into water with two thirds of the total water amount, and marking as a mixed solution 1; adding 2 parts of weighed defoamer into one third of the total water, and marking as mixed solution 2, wherein the total water is 140 parts;
2) Placing 985 parts of crushed stone, 700 parts of sand, 500 parts of cement, 75 parts of fly ash and 55 parts of silica fume in a stirrer, and stirring for 1min;
3) Adding the mixed solution 1 in the step 1) into a stirrer, and uniformly stirring for 2-3min;
4) Adding 12 parts of excitant calcium chloride into a stirrer, and uniformly stirring for 2-3min;
5) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a stirrer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
The concrete molding and curing method of the comparative example is as follows:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibrating table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod so as to discharge redundant bubbles in the concrete mixture; after molding, placing the test block in an environment with the temperature of 20+/-2 ℃, covering the surface of the test block with wetted geotextile, standing for 1d, removing the mold, and curing in a standard curing room with the temperature of 20+/-2 ℃ and the relative humidity of more than or equal to 95% until the required age.
The results of the performance test of the high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete prepared in examples 1-6 and the comparative concrete are shown in Table 1.
Table 1 comparison of the properties of examples 1-6 and comparative examples
As can be seen from Table 1, the high-toughness high-cohesiveness C150-strength ultrahigh-strength fiber concrete prepared by the invention meets the compressive and bending strength required by the member when loaded, and ensures the cohesiveness of the cooperative work with steel. The 28d cube compressive strength is not less than 152.65MPa, the flexural strength is not less than 38.36MPa, the splitting tensile strength is not less than 16.98MPa, the bonding strength with the section steel is not less than 8.06MPa, and the chloride ion migration coefficient is not more than 15 multiplied by 10 -14 m 2 And/s. Example 4 is an optimal blend ratio, its cement grain sizeFor the optimum, the carboxyl modified polyvinyl alcohol polymer is optimally doped, and the fiber is optimally doped. At the C150 strength level, the steel has enough toughness and cohesiveness to improve the cooperative working capacity of the section steel and the concrete, and can be applied as a modern green building material.
The foregoing is merely illustrative of the present invention and is not intended to limit the scope of the invention in any way, and persons skilled in the art may make simple changes or substitutions without departing from the spirit of the invention. The scope of the invention should be determined by the claims.

Claims (7)

1. The high-toughness high-cohesiveness C150-strength ultrahigh-strength fiber concrete is characterized by comprising the following raw materials in parts by weight:
460 parts of cement, 715 parts of sand, 985 parts of crushed stone, 80 parts of fly ash, 70 parts of straw ash, 45 parts of silica fume, 4 parts of nano silicon dioxide, 105 parts of water, 15.5 parts of water reducer, 12.9 parts of excitant, 2.4 parts of defoamer, 12 parts of shrinkage reducer, 5.7 parts of ramie fiber, 10.1 parts of basalt fiber, 17 parts of carboxyl modified polyvinyl alcohol polymer and 28 parts of hydroxyl modified single-wall carbon nanotube dispersion liquid;
the ramie fiber is refined dry ramie fiber after alkali treatment and drying, the length is 40-50mm, the diameter is 30-40 mu m, the tensile strength is more than or equal to 766MPa, the elastic modulus is more than or equal to 9.1GPa, the breaking elongation is 8.9%, and the specific gravity is 1.54-1.55g/cm 3 ；
The basalt fiber has a length of 12mm, a diameter of 7-15 μm, a tensile strength of not less than 3000MPa, an elastic modulus of not less than 91GPa and a specific gravity of 2.63-2.65 g/cm 3 ；
The exciting agent is an organic-inorganic composite exciting agent, and the composite exciting agent is prepared by compounding the following raw materials in percentage by mass:
55.2% of dihydrate gypsum, 43% of calcium chloride and 1.8% of triethanolamine;
the carboxyl modified polyvinyl alcohol polymer is prepared from the following raw materials in percentage by mass: 38.6% of carboxyl modified polyvinyl alcohol, 60.4% of water and 1% of polyacrylate defoamer, specifically, placing the carboxyl modified polyvinyl alcohol with the mass percentage of 38.6% into 60.4% of water, standing for 30min at normal temperature to fully swell the carboxyl modified polyvinyl alcohol, then placing the carboxyl modified polyvinyl alcohol into a constant-temperature water tank with the temperature of 95 ℃ for heating and dissolving, adding 1% of polyacrylate defoamer, and continuously stirring until a uniform transparent solution is formed, thus obtaining the carboxyl modified polyvinyl alcohol polymer;
The polymerization degree of the carboxyl modified polyvinyl alcohol is 2400, the alcoholysis degree is 99%, the carboxyl/hydroxyl molar ratio is 3/97, and the pH=7;
the 28d cube compressive strength of the C150 strength ultrahigh-strength fiber concrete reaches 157.52MPa, the flexural strength reaches 40.04MPa, the splitting tensile strength reaches 18.16MPa, the bonding strength with the section steel reaches 8.39MPa, and the chloride ion migration coefficient reaches 13 multiplied by 10 - 14 m 2 /s。
2. The high-toughness high-cohesiveness C150 strength ultra-high strength fiber concrete according to claim 1, wherein the cement is p.i62.5 r-grade portland cement;
the broken stone is basalt broken stone with good grading, compactness, hardness and rough surface, the broken stone with continuous grain size of 5-10mm and 10-15mm is mixed according to the mass ratio of 7:3, the parent rock strength is not lower than 250MPa, and the maximum grain size is not more than 15mm;
the fly ash adopts high-quality class I fly ash of a power plant, the screen residue of a 45 mu m square hole screen is not more than 10%, the water demand ratio is not more than 95%, and the specific surface area is more than 400m 2 /kg；
The silica content in the silica fume is more than 93%, the volcanic ash activity index is more than 95%, the average grain diameter is 0.1-0.15 μm, and the specific surface area is more than 25m 2 /g；
The nano silicon dioxide is prepared into high-purity nano silicon dioxide by a gas phase method, the purity is more than 99 percent, the average grain diameter is 10nm-40nm, and the specific surface area is more than 130m 2 /g；
The water reducer is a polycarboxylic acid high-performance water reducer, the solid content is 20%, and the water reducing rate of the water reducer is more than 35%.
3. The high-toughness high-cohesiveness C150 strength ultra-high strength fiber concrete according to claim 1, wherein the straw ash is prepared by burning mature stems of corn straw at 650-820 ℃, then carrying out potassium treatment, and grinding for 25min by using a ball mill, and has a silica content of more than 84.1%, an average particle size of 6-12 μm, and a specific surface area of more than 12m 2 /g。
4. The high-toughness high-cohesiveness C150 strength ultra-high strength fiber concrete according to claim 3, wherein the potassium removing treatment method comprises the steps of:
1) Placing the straw ash into distilled water for stirring and soaking, then standing, pouring out supernatant, continuously adding distilled water for stirring and soaking, and repeating the process for more than 5 times, wherein the soaking time lasts for one week;
2) Pouring out the supernatant liquid for the last time, heating to 90 ℃ with distilled water, preserving heat for 15-20min, adding distilled water for soaking after preserving heat, and repeating the step 1);
3) Repeating steps 1) and 2) twice in sequence;
4) Finally, the temperature is kept at 60 ℃ for 2 hours, and the supernatant is poured out and dried for standby.
5. The high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete according to claim 1, wherein the hydroxyl-modified single-walled carbon nanotube dispersion is prepared by the following method:
1) Adding 2 parts of single-wall carbon nanotubes into 120 parts of NaOH aqueous solution with the concentration of 3.0-5.0M according to the parts by weight, carrying out ultrasonic treatment for 15-20min, and stirring; sealing the carbon nanotube dispersion liquid at high pressure, and reacting for 180min at 200-260 ℃; cooling to room temperature, centrifugally separating, adding deionized water for dilution, and removing supernatant; then carrying out ultrasonic treatment for 20min, stirring, filtering by using a hydrophilic polytetrafluoroethylene filter membrane, and washing the obtained solid product to be neutral; drying for 12 hours at 40 ℃ to obtain the modified single-wall carbon nanotube with the surface containing hydroxyl functional groups;
2) Dispersing 1 part of surfactant polyethylene glycol octyl phenyl ether and 2 parts of modified single-walled carbon nanotube into 98 parts of deionized water in turn, stirring to ensure that the modified single-walled carbon nanotube is completely soaked by surfactant aqueous solution, carrying out ultrasonic treatment for 30min, and centrifuging and settling the dispersion;
3) The upper layer liquid is filtered by 500 meshes of filter cloth to obtain carbon nano tube dispersion liquid 1; carrying out ultrasonic treatment on the liquid with the precipitation agglomerated carbon nano tubes at the bottom for 60min again to obtain carbon nano tube dispersion liquid 2, wherein the carbon nano tube dispersion liquid is hydroxyl modified single-wall carbon nano tube dispersion liquid twice;
The average pipe diameter of the single-wall carbon nano-tube is 1-2nm, the length is 10-20 mu m, and the purity is more than or equal to 98%.
6. A method for preparing the high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete based on any one of claims 1 to 5, comprising the following steps:
1) Adding 15.5 parts by mass of water reducer and 28 parts by mass of hydroxyl modified single-wall carbon nanotube dispersion liquid into two-thirds of the total water, and marking as a mixed solution 1; adding 12 parts of weighed shrinkage reducing agent and 2.4 parts of defoamer into the rest one third of water, marking as mixed solution 2, and preparing 17 parts of carboxyl modified polyvinyl alcohol polymer for later use, wherein the total water quantity is 105 parts;
2) Dividing 5.7 parts of ramie fibers, 985 parts of crushed stone, 715 parts of sand, 460 parts of cement, 80 parts of fly ash, 70 parts of straw ash, 45 parts of silica fume, 4 parts of nano silicon dioxide and 10.1 parts of basalt fibers into three parts respectively, uniformly spreading one part of ramie fibers and basalt fibers in a disc mixer, and sequentially placing one part of crushed stone, sand, cement, fly ash, straw ash, silica fume and nano silicon dioxide in the disc mixer for stirring for 1min;
3) Adding the other two parts of materials into a disc stirrer in the same way to stir uniformly;
4) Adding the mixed solution 1 in the step 1) into a disc stirrer, and uniformly stirring for 2-3min;
5) Adding 17 parts of prepared carboxyl modified polyvinyl alcohol polymer and stirring for 2min;
6) Adding 12.9 parts of exciting agent into the disc mixer, and uniformly stirring for 2-3min;
7) Finally observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc mixer, uniformly stirring for 2-3min, after 3min intervals, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and forming and curing.
7. A molding curing method of high-toughness high-cohesiveness C150 strength ultrahigh-strength fiber concrete prepared based on the preparation method of claim 6 is characterized by adopting a standard curing method:
the standard curing method is as follows: pouring the concrete mixture into a cast iron mold for molding and compaction, standing for 1-2d in a standard curing chamber with the temperature of 20+/-2 ℃ and the relative humidity of more than or equal to 95%, removing the mold, and curing in the standard curing chamber to the required age.
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