CN113185212A - High-toughness high-cohesiveness C70-strength fiber concrete and preparation method thereof - Google Patents
High-toughness high-cohesiveness C70-strength fiber 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
- 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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
- B28B11/24—Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
- B28B11/245—Curing concrete articles
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- 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
- B28C5/40—Mixing specially adapted for preparing mixtures containing fibres
- B28C5/402—Methods
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- 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
- B28C5/40—Mixing specially adapted for preparing mixtures containing fibres
- B28C5/404—Pre-treatment of fibres
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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
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Abstract
The invention discloses a high-toughness high-cohesiveness C70 strength fiber concrete and a preparation method thereof, wherein the concrete comprises the following components in proportion: cement: river sand: crushing stone: fly ash: straw ash: silica fume: nano silicon: water: water reducing agent: exciting agent: defoaming agent: shrinkage reducing agent: ramie fiber: basalt fiber: CaCO3Whisker 350-: 723: 1010: 105-112: 45-55: 14-17: 2-3.5: 155-160: 7.5-8.5: 12-13: 1.8-2.1: 6.8-7.8: 4.7-4.9: 7.9-8.1: 17.3-17.5. And (3) uniformly mixing the materials at intervals by a layered stirring method, discharging, forming and maintaining. The compression resistance, the bending resistance, the split tensile strength, the toughness, the durability and the like of the concrete can be effectively improved, and the bonding strength and the cooperative deformation capability between the concrete and the section steel are enhanced.
Description
Technical Field
The invention belongs to the field of building materials, and relates to a ramie fiber, basalt fiber and CaCO doped fiber3The concrete with the whiskers, the straw ash, the fly ash, the silica fume and the nano-silicon has higher toughness, high cohesiveness, high durability and high volume stability, and particularly relates to high-toughness high-cohesiveness C70-strength fiber concrete and a preparation method thereof.
Background
In the structural design, the requirements of use function, member rigidity and construction convenience are considered, and concrete with different grades is generally adopted according to different stress conditions so as to meet the requirements of compression strength, bending strength and split tensile strength required by the member when the member is loaded and ensure the bonding strength of cooperative work of the concrete and steel. The concrete materials with different labels have different elastic moduli and different deformation properties, so that the too large or too small strength index can cause the deformation of steel and concrete to be inconsistent when the member is stressed, thereby causing that the two materials can not work in cooperation completely or one material can not fully exert the mechanical property, and causing the material waste. Ordinary concrete and high-performance concrete materials have poor anti-cracking performance and high brittleness, and the brittleness characteristic is more obvious along with the improvement of the concrete strength grade, and under the high stress or complex stress state, concrete with a specific high strength grade is often needed to be used, for example, in components of different floors or parts with lower stress in high-rise and super-high-rise structures, the concrete with the C70 strength grade needs to be used in particular sometimes in consideration of the bearing capacity, the rigidity requirement, the economic benefit, the design requirement and the like, and at the moment, the brittleness characteristic of the concrete can reduce the anti-seismic bearing capacity of the components and the structures and even influence the safety and reliability of the components and the structures. Meanwhile, with the gradual improvement of the mechanical property of steel, the toughness, the deformation property and the bonding property of common concrete are difficult to meet the synergistic action between the concrete and the section steel.
The silica fume has excellent particle size and pozzolanic activity, is an important mineral admixture for preparing high-performance concrete, but has low annual output in China, only 3000t-4000t, can only meet the requirements of partial high-performance concrete, and limits the use of the silica fume in large quantity. As a big agricultural country, China has more than 7 hundred million t of straw output every year and is the first place in the world. At present, only a small part of straws are used for power generation of a biomass energy power plant, and most of straws are still naturally stacked or burned in the open air, so that resource waste and environmental pollution are caused. If the straw ash generated by power generation of the power plant is not developed and utilized properly, secondary pollution to the environment can be caused. With the scientific and technological progress, the straw ash prepared by burning the corn straws under proper conditions contains about 85 percent of amorphous SiO2And a certain amount of active Al2O3The content of the metal oxide K, Na is less, the volcanic ash 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 improved by adding fibers, the existing steel fibers and synthetic fibers are difficult to popularize in concrete engineering application due to complex process, high cost and low yield, and the engineering industry gradually searches 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 acid and alkali resistance, is green and pollution-free, and can effectively replace steel fiber and synthetic fiber in engineering application. China is the main production area of ramie, and the yield accounts for more than 90% of the world, so that the ramie fibers are convenient to obtain in China, are low in price and have great popularization and application values. Meanwhile, because cracks with different sizes exist in concrete, the best toughening effect cannot be achieved by doping a single fiber.
Therefore, the development of the high-toughness and high-cohesiveness concrete with the strength grade of C70, higher toughness, high cohesiveness, high durability, better cooperative deformability and capability of cooperating with high-performance steel is very urgent.
Disclosure of Invention
The invention aims to provide high-toughness high-cohesiveness C70-strength fiber concrete used in members of different floors or parts with small stress in high-rise and super-high-rise structures and a preparation method thereof, wherein the concrete has high toughness, high cohesiveness, high durability, high volume stability and better cooperative deformability, and can better cooperate with steel.
In order to achieve the purpose, the technical scheme disclosed by the invention is as follows: the high-toughness high-cohesiveness C70-strength fiber concrete comprises the following raw materials in parts by weight:
360 parts of cement 350-containing material, 723 parts of river sand, 1010 parts of gravel, 112 parts of fly ash 105-containing material, 45-55 parts of straw ash, 14-17 parts of silica fume, 2-3.5 parts of nano silicon, 160 parts of water 155-containing material, 7.5-8.5 parts of water reducing agent, 12-13 parts of exciting agent, 1.8-2.1 parts of defoaming agent, 6.8-7.8 parts of shrinkage reducing agent, 4.7-4.9 parts of ramie fiber, 7.9-8.1 parts of basalt fiber, CaCO317.3 to 17.5 portions of whisker.
Further, the cement is P. O42.5R grade ordinary portland cement, and a cement variety with good compatibility with the polycarboxylic acid water reducing agent is selected.
The river sand is medium-coarse river sand with good gradation, and the fineness modulus is 2.8-3.0.
The crushed stone is selected from artificial crushed stone which is good in gradation, compact, hard and rough in surface and mainly comprises limestone, the particle size range is 5-15mm, and grading is carried out according to continuous particle size.
The fly ash is high-quality I-grade fly ash in a power plant, and the sieve residue of a 45-micron square-hole sieve of the fly ash is not more than 12 percent, the water demand ratio is not more than 95 percent, and the specific surface area is more than 400m2/kg。
The straw ash is prepared by burning stems of mature corn straws at the temperature of 600-820 ℃, performing potassium removal treatment, and then grinding for 20min by using a ball mill, wherein the content of silicon dioxide is more than 82.3%, the average particle size is 6-15 mu m, and the specific surface area is more than 10m2/g。
Further, the potassium removal treatment method comprises the following steps:
1) placing the straw ash in distilled water, stirring and soaking, standing, pouring out supernatant, continuing adding distilled water, stirring and soaking, repeating the process for more than 5 times, and keeping the soaking time for one week;
2) pouring out the supernatant at the last time, heating to 90 ℃ with distilled water, preserving heat for 15-20min, adding distilled water for soaking after heat preservation, and repeating the step 1);
3) repeating the steps 1) and 2) for two more times in sequence;
4) and finally, preserving the heat at 60 ℃ for 2h, pouring out the supernatant and drying for later use.
The silica fume has silica content higher than 90%, average particle size of 0.1-0.3 μm, and specific surface area higher than 20m2/g；
The nano silicon is high-purity nano silicon dioxide prepared by a vapor phase method, the purity is more than 99 percent, the average particle size is 10nm-40nm, and the specific surface area is more than 130m2/g。
The water reducing agent is a polycarboxylic acid high-performance water reducing agent, the solid content is 20%, the water reducing rate is more than 30%, and the water reducing agent has no adverse effect on the compressive strength of concrete.
The shrinkage reducing agent is SU-SRA type shrinkage reducing agent.
The defoaming agent is a high-efficiency concrete defoaming agent of the Liqi X-2756.
The excitant is an organic-inorganic composite excitant which is compounded by 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 after alkali treatment and dryingDry hemp fiber with length of 40-50mm, diameter of 30-40 μm, tensile strength not less than 1000MPa, elastic modulus not less than 11.4GPa, elongation at break up to 8.9%, specific gravity of 1.54-1.55g/cm3Has good hydrophilicity, higher bond stress and acid and alkali resistance.
The length of the basalt fiber is 12mm, the diameter is 7-15 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/cm3；
The CaCO3The length of the whisker is 20-30 μm, the diameter is 0.5-2 μm, the tensile strength is more than or equal to 3000MPa, the elastic modulus is more than or equal to 410GPa, and the specific gravity is 2.86g/cm3.
The invention also discloses a preparation method of the high-toughness high-cohesiveness C70-strength fiber concrete, which comprises the following steps:
1) adding 7.5-8.5 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 6.8-7.8 parts of shrinkage reducing agent and 1.8-2.1 parts of defoaming agent which are weighed into water with one third of the total water amount, and marking as a mixed solution 2; the total water amount is 155-160 parts;
2) respectively mixing 4.7-4.9 parts of ramie fiber, 1010 parts of gravel, 723 parts of river sand, 360 parts of 350-containing cement, 112 parts of fly ash, 45-55 parts of straw ash, 14-17 parts of silica fume, 2-3.5 parts of nano silicon, 7.9-8.1 parts of basalt fiber and 17.3-17.5 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and then sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer to stir for 1 min;
3) adding the other two parts of the materials in the step 2) into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12-13 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The concrete molding and curing method obtained by the preparation method comprises the following steps:
standard maintenance: pouring the concrete mixture into a cast iron mold for molding, compacting, standing for 1d-2d in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95 percent, removing the mold, and curing in the standard curing room to the required age.
In order to overcome the problems of large brittleness, low toughness, poor durability, poor bonding performance with section steel and the like of common concrete, the invention utilizes materials which are easy to obtain in the market, adopts an improved concrete layered stirring process, considers the dosage proportion of each cementing material required by a specific concrete strength grade and the number and size distribution of cracks in a cement matrix under corresponding proportion, controls the continuous grain composition design with the cementing material based on multi-scale crack classification, and adds ramie fibers, basalt fibers and CaCO3The fiber concrete with high toughness and high bonding property C70 strength is prepared from three active mineral admixtures with different particle size ranges, such as fiber with different sizes, fly ash, straw ash, silica fume, nano-silicon and the like, and chemical admixtures, such as a water reducing agent, an exciting agent and the like. Wherein, the ramie fiber with water storage function and toughening function is adopted, which can play an 'internal curing' role in the hydration process of concrete, can promote the hydration process of a cementing material, and simultaneously, the basalt fiber and CaCO are used in a matching way3The crystal whisker bridges cracks with different scales in the concrete, effectively inhibits the development of the cracks and enhances the toughness of the concrete; in addition, mineral admixtures with different particle sizes are added into the concrete, wherein the mineral admixtures comprise fly ash, straw ash, silica fume and nano-silica with nano-scale, on one hand, continuous particle grading is formed among all cementing materials, so that the micro-aggregate filling effect can be more effectively exerted, on the other hand, all the mineral admixtures can exert the volcanic ash effect and the super-superposition effect, improve the concrete hydration products, reduce the pore size, reduce the number of harmful pores and improve the compactness of the concrete, thereby realizing the two aspects ofUnder the combined action of the surfaces, the bonding interface between the concrete and the section steel is more compact, the bonding force is further improved along with the improvement of the form of the hydration product, and simultaneously, the bond property between the concrete matrix and the fiber material is enhanced, so that the fibers can act in a synergistic manner, the toughness of the concrete is further improved, and Cl can be effectively reduced-、SO4 2-、CO2And the invasion of harmful ions improves the durability of the concrete. According to the invention, through the synergistic effect among the components, the pore structure of the concrete is improved, the internal structure of the concrete is more compact, the hydration shrinkage of the concrete and the development of cracks with different scales under a stress state are inhibited in a targeted manner, 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 fibers used in the invention are long fibers of 40-50mm, have 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 ramie fibers have natural hydrophilicity, so that the surfaces of the ramie fibers have strong bond force, the ramie fibers have good bonding capacity with a cement matrix, and the long fibers have enough anchoring length, so that the ramie fibers can effectively prevent the fibers from being pulled out when concrete cracks, the further development of the cracks is prevented, and the deformation and energy consumption capacity 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 water, so that the internal curing effect is achieved, and the hydration process of concrete is promoted. Therefore, the ramie fiber can improve the mechanical property and the durability of the concrete, such as crack resistance, permeability resistance, freeze-thaw resistance and the like.
2) Basalt fiber and CaCO used in the present invention3The whisker has the characteristics of high strength and high elastic modulus, has the lengths of 12mm and 20-30 mu m respectively, can effectively inhibit the formation and development of cracks caused by factors such as plastic shrinkage, dry shrinkage, temperature change and the like of concrete, can work with ramie fibers in a synergistic manner to play a bridging role, and can be used for developing cracks with different scales in the concreteThe strength, toughness, deformation performance and durability of the concrete can be effectively improved by carrying out grading control; in addition, when the invention is used for a section steel concrete composite structure, three fibers are uniformly dispersed in concrete to form a spatial three-dimensional network structure, so that crack development of surrounding concrete is effectively restrained when section steel is stressed, and an annular restraining effect is formed on the section steel, so that the friction force and the mechanical occlusion force between the section steel and the concrete are effectively improved, the binding force between the concrete and the section steel is further enhanced, and the concrete and the section steel can better cooperate.
3) The invention considers that potassium ions in straw crops are mainly enriched in new leaves and spores, mature stems are low in content and different types of straw crops are different in potassium ion content, the mature stems of corn straws with low potassium ion content are selected to be combusted at a certain temperature, and then potassium and sodium removal treatment is carried out on the mature stems in a simple, feasible and low-cost potassium removal mode, so that alkali aggregate reaction in concrete can be effectively prevented, the straw ash obtained by grinding after potassium removal treatment contains more than 82.3% of silicon dioxide and a certain amount of active Al and Fe oxides, and has high pozzolan activity, the straw ash has fine particles (the average particle size is 6-15 mu m), and the internal porous gaps and the network structure of the straw ash particles enable the straw ash particles to have large specific surface area and can reach 10m2(ii) in terms of/g. The straw ash is doped, so that the particles of the cementing material are more uniform, the grading is good, the filling and compacting effects can be achieved, and the cohesiveness of the concrete is further improved; in addition, the straw ash has similar pozzolanic activity with the silica fume, can replace part of the silica fume and is Ca (OH) in a concrete system2Compact and hard hydrated calcium sulphoaluminate and more stable C-S-H gel are generated by reaction, and the breaking strength, the compressive strength, the splitting tensile strength and the durability of the concrete are improved; finally, the straw ash is used as agricultural waste, and is treated to be used as a building material to replace part of cement, so that CO generated in straw burning and cement production processes can be reduced2The discharge amount is reduced, the manufacturing cost of concrete is further reduced, the agricultural waste is recycled, and the purposes of energy conservation and environmental protection are achieved.
4) The fly ash, the straw ash, the silica fume and the nano-silica which are added in the inventionThe nanometer silicon dioxide can enter more tiny pores, the surface of the nanometer silicon dioxide has more unsaturated bonds and larger surface energy, and the hydration products, especially Ca (OH) ()2The gel is quickly gathered on the surface to react, thereby promoting the growth of the C-S-H gel by taking the gel as a core, limiting the generation of harmful crystals, strengthening the interface structure of a cement matrix, and further improving the breaking strength, the compressive strength, the splitting tensile strength, the toughness, the bonding property and the durability of the concrete.
5) The shrinkage reducing agent used in the invention can reduce the surface tension of water in concrete capillary pores to compact a concrete structure, further control the volume shrinkage, drying shrinkage, early-stage hardening plastic shrinkage and the like of the concrete, further improve the crack resistance and permeability resistance of the concrete and enhance the durability of the concrete.
6) The activator adopts an organic-inorganic composite activator, and the dihydrate gypsum, the calcium chloride and the triethanolamine play an activating role together to promote the generation of the ettringite, so that the concrete doped with the fly ash, the silica fume, the nano-silica and the straw ash has certain micro-expansibility, and the shrinkage performance of the concrete is improved. The net structure of the fly ash surface vitreous body is depolymerized through the composite activator, so that the potential activity of the fly ash is excited, the corrosion effect of the three-dimensional space structure vitreous body which takes aluminosilicate as a main hydration component in the fly ash hydration process can be enhanced, the power of a forward hydration reaction is improved, more C-S-H gel, hydrated calcium aluminate and other crystals are generated, and the participation of the fly ash in an early hydration process is promoted. The excitation effect of the dihydrate gypsum on the mineral admixture is shown as follows: SO (SO)4-Gel on the surface of fly ash particles and AlO dissolved in liquid phase2-Reacting to generate hydrated calcium sulphoaluminate AFt; in addition, SO4 2-Can also displace part of calcium silicate hydrateSiO2 2-Replaced SiO2 2-In the outer layer, Ca is further mixed with2+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 hydrate2+Mixing with fly ash, silica fume, nano-silicon dioxide and SiO in straw ash2、Fe2O3、Al2O3The reaction generates hydrated calcium silicate, hydrated calcium ferrite, hydrated calcium aluminate and the like. The excitation of the mineral admixture by calcium chloride is mainly realized by increasing Ca in a hydration system2+The concentration, the formation of hydrated chloroaluminate gelled phase and the hydrated calcium aluminate are realized, and in addition, the calcium chloride serving as a strong electrolyte can supplement Ca required by the reaction of the siliceous dust, the straw ash and the nano-silica in the process of exciting the activity of the fly ash by the sulfate2+. Triethanolamine is used as an organic fly ash activity excitant, and can promote the corrosion of the surfaces of particles such as fly ash and the like by complexing Fe and Al phases in the fly ash and the like in the hydration process, so that active substances in the fly ash are further hydrated. The synergistic effect among the dihydrate gypsum, the calcium chloride and the triethanolamine can fully stimulate the activity of the mineral admixture, accelerate the hydration rate of the cementing material in the system, promote the generation of hydration products, and further improve the strength, the durability and the like of the concrete.
7) According to the invention, a layered stirring method is adopted, and the particle size of the largest crushed stone particle is determined through tests, so that long fibers and aggregates can be uniformly dispersed to the greatest extent, and the phenomena of large holes and even honeycomb pitted surface in a cement matrix caused by mutual interference of the long fibers and the coarse aggregates and fiber aggregation are avoided.
The measures can effectively improve the compressive strength, toughness, deformability, durability and the like of the concrete, and enhance the bonding strength and the cooperative deformability between the concrete and the section steel. The high-toughness and high-cohesiveness C70-strength fiber concrete prepared by the method has the advantages that the particle sizes of various gelled materials with different particle diameters in the concrete are uniformly distributed from large to small, the micro-aggregate filling effect of the gelled materials is fully exerted, the hydration products of the gelled materials can be stacked and compacted, and the concrete quality is further improvedThe pore structure and the multi-scale fibers are uniformly dispersed, and the development of cracks with different sizes is effectively inhibited, so that the concrete has higher toughness and excellent durability, has better adhesive property with the section steel, further improves the deformability, and enhances the cooperativity with the section steel. The 28d cubic compressive strength of the fiber concrete is not less than 71.89MPa, the flexural strength is not less than 20.61MPa, the splitting tensile strength is not less than 8.96MPa, the bonding strength between the fiber concrete and the section steel is not less than 4.91MPa, and the chloride ion migration coefficient is not more than 64 multiplied by 10-14m2And s. The high-performance fiber concrete with high volume stability, high durability and high toughness is prepared by the method, the raw materials are easy to obtain, the preparation process is simple, the requirements of sustainable development and application and popularization of modern green building materials are met, and the method is a novel green and environment-friendly high-performance fiber concrete material.
Detailed Description
The present invention will be further described in detail with reference to the following examples, which are provided to enable those skilled in the art to more easily understand the advantages of the present invention, but are not intended to limit the scope of the present invention.
The invention relates to a high-toughness high-cohesiveness C70 strength fiber concrete, which is prepared by the following method:
1) adding 7.5-8.5 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 6.8-7.8 parts of shrinkage reducing agent and 1.8-2.1 parts of defoaming agent which are weighed into water with one third of the total water amount, and marking as a mixed solution 2; the total water amount is 155-160 parts;
2) respectively mixing 4.7-4.9 parts of ramie fiber, 1010 parts of gravel, 723 parts of river sand, 360 parts of 350-containing cement, 112 parts of fly ash, 45-55 parts of straw ash, 14-17 parts of silica fume, 2-3.5 parts of nano silicon, 7.9-8.1 parts of basalt fiber and 17.3-17.5 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and then sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer to stir for 1 min;
3) adding the other two parts of the materials in the step 2) into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12-13 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The forming and curing method of the concrete comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
Wherein:
the cement is commercial P. O42.5R grade ordinary portland cement, and has good compatibility with polycarboxylic acid water reducing agent.
The river sand is medium coarse river sand with fineness modulus of 2.9 and apparent density of 2.59g/cm3Bulk density of 1.48g/cm3。
The crushed stone is dense hard limestone with rough surface, particle size of 5-15mm, uniform continuous gradation, and apparent density of 2.7g/cm3Bulk density of 1.51g/cm3。
The fly ash is high-quality class I fly ash in a power plant, the residue of a 0.045mm square-hole sieve is not more than 12 percent, and the specific surface area is more than 400m2Per kg, the average particle diameter is in the range of 15-30 μm.
The straw ash is prepared by burning stems of mature corn straws at the temperature of 600-820 ℃, and then burning the stemsRemoving potassium, and grinding with ball mill for 20min to obtain the final product with silicon dioxide content of more than 82.3%, average particle diameter of 6-15 μm, and specific surface area of more than 10m2/g。
The potassium removal treatment method comprises the following steps:
1) placing the straw ash in distilled water, stirring and soaking, standing, pouring out supernatant, continuing adding distilled water, stirring and soaking, repeating the process for more than 5 times, and keeping the soaking time for one week;
2) pouring out the supernatant at the last time, heating to 90 ℃ with distilled water, preserving heat for 15-20min, adding distilled water for soaking after heat preservation, and repeating the step 1);
3) repeating the steps 1) and 2) for two more times in sequence;
4) and finally, preserving the heat at 60 ℃ for 2h, replacing supernatant liquor with distilled water, and drying for later use.
The silica fume has silica content greater than 90%, average particle diameter of 0.1-0.3 μm, and specific surface area greater than 20m2/g；
The high-purity nano silicon dioxide is prepared 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 130m2/g。
The water reducing agent is a polycarboxylic acid high-performance water reducing agent, the solid content is 20%, the pH value is 8.0, the water reducing rate is more than 30%, and the compressive strength ratio of 7d to 28d is not less than 150%.
The shrinkage reducing agent is SU-SRA type shrinkage reducing agent.
The used defoamer is a high-efficiency concrete defoamer of the Liqi X-2756.
The excitant is an organic-inorganic composite excitant which is compounded by 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 alkali-treated and dried degummed ramie fiber with the length of 40-50mm, the diameter of 30-40 μm, the tensile strength of more than or equal to 1000MPa, the elastic modulus of more than or equal to 11.4GPa, the breaking elongation of 8.9 percent and the specific gravity of 1.54-1.55g/cm3。
The basalt fiber has length of 12mm and diameter7-15 μm, tensile strength not lower than 3000MPa, elastic modulus not lower than 91GPa, specific gravity 2.63-2.65g/cm3；
CaCO used3The length of the whisker is 20-30 μm, the diameter is 0.5-2 μm, the tensile strength is more than or equal to 3000MPa, the elastic modulus is more than or equal to 410GPa, and the specific gravity is 2.86g/cm3.
The following specific examples are given to further illustrate the preparation process of the present invention.
Example 1
1) Adding 8 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 7.5 parts of weighed shrinkage reducing agent and 1.9 parts of defoaming agent into one third of water of the total water amount, and marking as a mixed solution 2, wherein the total water amount is 160 parts;
2) 4.8 parts of ramie fiber, 1010 parts of broken stone, 723 parts of river sand, 360 parts of cement, 110 parts of fly ash, 50 parts of straw ash, 16 parts of silica fume, 3 parts of nano-silicon, 8.1 parts of basalt fiber and 17.4 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer for stirring for 1 min;
3) adding the other two materials into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12.5 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min; the exciting agent is compounded from the following raw materials in percentage by mass: 52.5 percent of dihydrate gypsum, 46 percent of calcium chloride and 1.5 percent of triethanolamine;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The forming and curing method of the concrete comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
Example 2
1) Adding 8.5 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 7.8 parts of shrinkage reducing agent and 2.1 parts of defoaming agent which are weighed into water with one third of the total water amount, and marking as a mixed solution 2, wherein the total water amount is 155 parts;
2) 4.9 parts of ramie fiber, 1010 parts of broken stone, 723 parts of river sand, 360 parts of cement, 109 parts of fly ash, 55 parts of straw ash, 17 parts of silica fume, 2 parts of nano-silicon, 8.1 parts of basalt fiber and 17.5 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer for stirring for 1 min;
3) adding the other two materials into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 13 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min; the exciting agent is compounded from the following raw materials in percentage by mass: 55.2% of dihydrate gypsum, 43% of calcium chloride and 1.8% of triethanolamine;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The forming and curing method of the concrete comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
Example 3
1) Adding 8 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 7.5 parts of weighed shrinkage reducing agent and 1.9 parts of defoaming agent into one third of water of the total water amount, and marking as a mixed solution 2, wherein the total water amount is 160 parts;
2) 4.7 parts of ramie fiber, 1010 parts of broken stone, 723 parts of river sand, 360 parts of cement, 112 parts of fly ash, 45 parts of straw ash, 15 parts of silica fume, 2 parts of nano-silicon, 7.9 parts of basalt fiber and 17.4 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer for stirring for 1 min;
3) adding the other two materials into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min; the exciting agent is prepared by compounding the following raw materials in percentage by mass: 58% of dihydrate gypsum, 40% of calcium chloride and 2% of triethanolamine;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The forming and curing method of the concrete comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
Example 4
1) Adding 8.5 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 6.8 parts of weighed shrinkage reducing agent and 1.8 parts of weighed defoaming agent into one third of water of the total water amount, and marking as a mixed solution 2, wherein the total water amount is 157 parts;
2) 4.8 parts of ramie fiber, 1010 parts of broken stone, 723 parts of river sand, 360 parts of cement, 108 parts of fly ash, 50 parts of straw ash, 14 parts of silica fume, 3.5 parts of nano-silicon, 7.9 parts of basalt fiber and 17.4 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer for stirring for 1 min;
3) adding the other two materials into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12.3 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min; the exciting agent is compounded from the following raw materials in percentage by mass: 55.2% of dihydrate gypsum, 43% of calcium chloride and 1.8% of triethanolamine;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The forming and curing method of the concrete comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
Example 5
1) Adding 7.5 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 7.8 parts of weighed shrinkage reducing agent and 1.9 parts of defoaming agent into one third of water of the total water amount, and recording as a mixed solution 2, wherein the total water amount is 155 parts;
2) 4.9 parts of ramie fiber, 1010 parts of crushed stone, 723 parts of river sand, 360 parts of cement, 105 parts of fly ash, 55 parts of straw ash, 14 parts of silica fume, 3.5 parts of nano-silicon, 8 parts of basalt fiber and 17.4 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer for stirring for 1 min;
3) adding the other two materials into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12.8 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min; the exciting agent is compounded from the following raw materials in percentage by mass: 55.2% of dihydrate gypsum, 43% of calcium chloride and 1.8% of triethanolamine;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The forming and curing method of the concrete comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
Example 6
1) Adding 7.5 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 7 parts of weighed shrinkage reducing agent and 2 parts of defoaming agent into one third of water in the total water amount, and marking as a mixed solution 2, wherein the total water amount is 157 parts;
2) 4.7 parts of ramie fiber, 1010 parts of broken stone, 723 parts of river sand, 360 parts of cement, 110 parts of fly ash, 45 parts of straw ash, 15 parts of silica fume, 3 parts of nano-silicon, 8 parts of basalt fiber and 17.4 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer for stirring for 1 min;
3) adding the other two materials into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min; the exciting agent is compounded from the following raw materials in percentage by mass: 52.5 percent of dihydrate gypsum, 46 percent of calcium chloride and 1.5 percent of triethanolamine.
6) Finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
The forming and curing method of the concrete comprises the following steps:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
The following is a comparison of comparative examples with examples of the present invention to further illustrate the effects of the present invention.
Comparative example: the common high-strength concrete is designed without adopting the continuous gradation of gelled particles and is not doped with fibers.
The mixture ratio is as follows: 524 parts of cement, 723 parts of river sand, 1010 parts of broken stone, 153 parts of water and 7 parts of a water reducing agent.
The preparation method comprises the following steps:
1) adding 7 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; the total water amount is 153 parts;
2) putting 1010 parts of broken stone, 723 parts of sand and 524 parts of cement into a stirrer, and stirring for 1 min;
3) adding the mixed solution 1 in the step 1) into a stirrer, and uniformly stirring for 2-3 min;
4) uniformly stirring for 2-3min at an interval of 1 min;
5) finally, observing the fluidity of the mixture, continuously adding the remaining one third of water into the stirrer, uniformly stirring for 2-3min, after 3min, stirring for 2-3min until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
Comparative example the concrete moulding and curing method described above was as follows:
pouring the concrete mixture into a cast iron mold for molding, compacting by using a vibration table, and then performing contact vibration along the outer wall of the test mold by using a vibrating rod to discharge redundant air 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 wet geotextile, standing for 1d, removing the mold, and then curing in a standard curing room with the temperature of 20 +/-2 ℃ and the relative humidity of more than or equal to 95% to the required age.
The results of the performance tests of the high tenacity, high bond C70 strength fiber concrete prepared in examples 1-6 and the comparative example concrete are shown in Table 1.
TABLE 1 comparison of the Properties of examples 1-6 with comparative examples
As can be seen from Table 1, the high-toughness and high-cohesiveness C70-strength fiber concrete prepared by the invention meets the compressive strength and bending strength required by the member when loaded, and ensures the cohesive strength of the member working in cooperation with steel. The 28d cubic compressive strength is not less than 71.89MPa, the flexural strength is not less than 20.61MPa, the splitting tensile strength is not less than 8.96MPa, the bonding strength between the structural steel and the structural steel is not less than 4.91MPa, and the chloride ion migration coefficient is not more than 64 multiplied by 10-14m2And/s, the example 1 is the optimal mixing ratio, the particle composition of the cementing material is optimal, and the fiber mixing amount is optimal. Under the strength grade of C70, the composite material has enough toughness and cohesiveness to improve the cooperative working capability of the section steel and the concrete, and can be applied as a modern green building material.
The above description is only an example of the present invention, and is further detailed description of the present invention with reference to specific preferred embodiments, and therefore, the protection scope of the present invention should not be limited thereby, and those skilled in the art can make simple changes or substitutions by using the disclosure and method of the present invention or without departing from the concept of the present invention, and should be considered as being within the protection scope of the present invention. The scope of the present invention shall be subject to the protection scope defined by the claims of the present disclosure.
Claims (10)
1. The high-toughness high-cohesiveness C70-strength fiber concrete is characterized by comprising the following raw materials in parts by weight:
360 parts of cement 350-containing material, 723 parts of river sand, 1010 parts of gravel, 112 parts of fly ash 105-containing material, 45-55 parts of straw ash, 14-17 parts of silica fume, 2-3.5 parts of nano silicon, 160 parts of water 155-containing material, 7.5-8.5 parts of water reducing agent, 12-13 parts of exciting agent, 1.8-2.1 parts of defoaming agent, 6.8-7.8 parts of shrinkage reducing agent, 4.7-4.9 parts of ramie fiber, 7.9-8.1 parts of basalt fiber, CaCO317.3 to 17.5 portions of whisker.
2. The high-toughness high-cohesiveness C70 strength fiber concrete according to claim 1, wherein said cement is P O42.5R grade Portland cement, and is selected from cement having good compatibility with polycarboxylic acid water reducer;
selecting medium-coarse river sand with good gradation from the river sand, wherein the fineness modulus is 2.8-3.0;
the crushed stone is selected from artificial crushed stone which is good in gradation, compact, hard and rough in surface and mainly comprises limestone, and the particle size range is 5mm-15 mm;
the fly ash is high-quality class I fly ash of a power plant, the sieve residue of a 45-micron square-hole sieve is not more than 12 percent, the water demand ratio is not more than 95 percent, and the specific surface area is more than 400m2/kg；
The water reducing agent is a polycarboxylic acid high-performance water reducing agent, the solid content is 20%, and the water reducing rate of the water reducing agent is more than 30%;
the defoaming agent is a high-efficiency concrete defoaming agent of the Liqi X-2756;
the shrinkage reducing agent is SU-SRA type shrinkage reducing agent.
3. The high-toughness high-cohesiveness C70 strength fiber concrete according to claim 1, wherein the straw ash is prepared from mature stems of corn stalks by incineration at a temperature of 600-820 ℃, followed by potassium removal treatment and subsequent grinding for 20min by using a ball mill; the content of silicon dioxide is more than 82.3%, and the average particle diameter is 6-15 μmSurface area greater than 10m2/g。
4. The high-toughness high-cohesiveness C70 strength fiber concrete according to claim 3, wherein said straw ash potassium-removing treatment method comprises the following steps:
1) placing the straw ash in distilled water, stirring and soaking, standing, pouring out supernatant, continuing adding distilled water, stirring and soaking for more than 5 times, and keeping the soaking time for one week;
2) pouring out the supernatant at the last time, heating to 90 ℃ with distilled water, preserving heat for 15-20min, adding distilled water for soaking after heat preservation, and repeating the step 1);
3) repeating steps 1) -2) twice;
4) and finally, preserving the heat at 60 ℃ for 2h, pouring out the supernatant and drying for later use.
5. The high tenacity high cohesive C70 strength fiber concrete according to claim 1, wherein the silica content in said silica fume is more than 90%, the average particle size is 0.1-0.3 μm, and the specific surface area is more than 20m2/g；
The nano silicon is high-purity nano silicon dioxide prepared by a vapor phase method, the purity is more than 99 percent, the average particle size is 10nm-40nm, and the specific surface area is more than 130m2/g。
6. The high-toughness high-cohesiveness C70-strength fiber concrete according to claim 1, wherein the activator is an organic-inorganic composite activator, and the composite activator is compounded from the following raw materials in percentage by mass:
50-58% of dihydrate gypsum, 40-48% of calcium chloride and 1.5-2% of triethanolamine.
7. The high-toughness high-cohesiveness C70-strength fiber concrete according to claim 1, wherein the ramie fiber is alkali-treated and dried degummed ramie fiber, the length of the degummed ramie fiber is 40-50mm, the diameter of the degummed ramie fiber is 30-40 μm, the tensile strength of the degummed ramie fiber is not less than 766MPa, the elastic modulus of the degummed ramie fiber is not less than 9.1GPa, and the elongation at break of the degummed ramie fiber is 8.9%Specific gravity of 1.54-1.55g/cm3；
The length of the basalt fiber is 12mm, the diameter is 7-15 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/cm3；
The CaCO3The length of the whisker is 20-30 μm, the diameter is 0.5-2 μm, the tensile strength is more than or equal to 3000MPa, the elastic modulus is more than or equal to 410GPa, and the specific gravity is 2.86g/cm3。
8. The high-toughness high-cohesiveness C70 strength fiber concrete according to claim 1, wherein the fiber concrete has 28d cube compressive strength of not less than 71.89MPa, breaking strength of not less than 20.61MPa, tensile strength at split of not less than 8.96MPa, and cohesiveness with section steel of not less than 4.91MPa, and chloride ion migration coefficient of not more than 64 x 10-14m2/s。
9. A method for preparing high-toughness high-cohesiveness C70-strength fiber concrete based on any one of claims 1-8, which comprises the following steps:
1) adding 7.5-8.5 parts by mass of a water reducing agent into two thirds of the total water amount, and marking as a mixed solution 1; adding 6.8-7.8 parts of shrinkage reducing agent and 1.8-2.1 parts of defoaming agent which are weighed into water with one third of the total water amount, and marking as a mixed solution 2; the total water amount is 155-160 parts;
2) respectively mixing 4.7-4.9 parts of ramie fiber, 1010 parts of gravel, 723 parts of river sand, 360 parts of 350-containing cement, 112 parts of fly ash, 45-55 parts of straw ash, 14-17 parts of silica fume, 2-3.5 parts of nano silicon, 7.9-8.1 parts of basalt fiber and 17.3-17.5 parts of CaCO3Dividing the crystal whisker into three parts according to the mass fraction, and then dividing one part of ramie fiber, basalt fiber and CaCO3Uniformly spreading the whiskers in a disc type stirrer, and then sequentially placing a part of broken stone, river sand, cement, fly ash, straw ash, silica fume and nano-silicon in the disc type stirrer to stir for 1 min;
3) adding the other two parts of the materials in the step 2) into a disc type stirrer in the same way and stirring uniformly;
4) adding the mixed solution 1 in the step 1) into a disc type stirrer, and uniformly stirring for 2-3 min;
5) adding 12-13 parts of exciting agent into the disc type stirrer, and uniformly stirring for 2-3 min;
6) finally, observing the fluidity of the mixture, continuously adding the mixed solution 2 prepared in the step 1) into a disc type stirrer, uniformly stirring for 2-3min, stirring for 2-3min after 3min intervals until the mixture is uniform, and discharging to obtain the prepared concrete mixture; and molding and maintaining.
10. The forming and curing method of the high-toughness high-cohesiveness C70-strength fiber concrete based on the claim 9 is characterized in that the standard curing method is adopted:
the standard maintenance method comprises the following steps: pouring the concrete mixture into a cast iron mold, molding, compacting, standing for 1-2 days in a standard curing room 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 room to the required age.
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