High-toughness high-cohesion c70-strength fiber concrete and method for preparing the same

Abstract

The application discloses high-toughness and high-bonding C70 strength fiber concrete and a preparation method thereof. A concrete mixing ratio comprises cement, river sand, gravel, fly ash, straw ash, silica fume, nano silicon, water, water reducing agent, activator, defoaming agent, shrinkage reducing agent, ramie fiber, basalt fiber and CaCO3 whisker, and the concrete mixing ratio is 350-360:723:1010:105-112:45-55:14-17:2-3.5:155-160:7.5-8.5:12-13:1.8-2.1:6.8-7.8:4.7-4.9:7.9-8.1:17.3-17.5. The materials are uniformly mixed by a layered mixing method, and then discharged, molded and maintained. The compressive strength, flexural strength, splitting tensile strength, toughness, durability and the like of the concrete can be effectively improved, and the bonding strength and the synergic deformation capacity between the concrete and the profile steel can be enhanced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of building materials, and is a kind of concrete with high toughness, high cohesiveness, high durability and high volume stability, which is mixed with ramie fiber, basalt fiber, CaCO3 whisker, straw ash, fly ash, silica ash and nano silicon, and specifically relates to a kind of fiber concrete with high toughness and high cohesiveness of C70 strength and a preparation method thereof. BACKGROUND

[0002] In structural design, considering the use function, component rigidity and the demand of construction convenience, different grade concrete is usually adopted for different stress conditions to meet the compressive strength, bending strength and splitting tensile strength required when the component is under load, and to ensure the cohesive strength of concrete and steel working together. Different grade concrete materials have different elastic modulus and deformation performance, so that the strength index is too large or too small, which will cause the deformation of steel and concrete to be not coordinated when the component is under load, so that the two materials cannot work together completely or one material cannot fully exert its mechanical properties, resulting in material waste. The crack resistance of ordinary concrete and high performance concrete material is poor, and the brittleness is large, and with the increase of concrete strength grade, the brittleness feature becomes more and more obvious, and in high stress or complex stress state, specific high strength grade concrete is often needed, such as in high-rise, super high-rise structure, considering the bearing capacity, rigidity demand, economic benefit, design demand and the like, sometimes C70 strength grade concrete is needed, at this time, the brittleness feature of concrete will reduce the seismic bearing capacity of component and structure, and even affect the safety and reliability. At the same time, with the gradual improvement of the mechanical properties of steel, the toughness, deformation performance and cohesive performance of ordinary concrete cannot meet the synergistic effect between concrete and profiled steel.

[0003] Silica ash has excellent particle size and pozzolanic activity, and is an important mineral admixture for preparing high performance concrete, but its annual output in China is only 3000t-4000t, which can only meet the demand of part of high performance concrete, limiting its large-scale use. China is a large agricultural country, and the annual straw yield is more than 700 million tons, ranking first in the world. At present, only a small part of the straw is used for biomass power plant, and most of the straw is still naturally stacked or open-air burned, causing resource waste and environmental pollution. If the straw ash generated by power generation is not properly developed and utilized, it will cause secondary pollution to the environment. With the progress of science and technology, it is found that under appropriate conditions, the straw ash prepared by burning corn straw contains about 85% of amorphous SiO2 and a certain amount of active Al2O3 and other metal oxides, and less K and Na, which can fully exert the pozzolanic effect and micro-aggregate filling effect, and can be applied in concrete to improve the mechanical properties.

[0004] Concrete and cement-based composite materials are usually improved in toughness by adding fibers, and existing steel fibers and synthetic fibers are difficult to popularize in concrete engineering applications due to complex process, high cost and low yield, and the engineering field gradually begins to look for abundant high-performance plant fibers to replace steel fibers and synthetic fibers. 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 fibers and synthetic fibers in engineering applications. China is the main production area of ramie, and the output accounts for more than 90% of the world, which makes ramie fiber easy to obtain in China, low in price and has great popularization and application value. At the same time, due to the existence of cracks of different sizes in concrete, adding a single fiber often cannot achieve the best toughening effect.

[0005] Therefore, it is very urgent to develop a C70 strength grade high-toughness high-adhesion concrete with high toughness, high adhesion, high durability, good synergistic deformation ability and the ability to work with high-performance steel. SUMMARY

[0006] The purpose of the present application is to provide a high-toughness high-adhesion C70 strength fiber concrete used in components of different floors or parts with smaller stress in high-rise and super high-rise structures and a preparation method thereof, which has high toughness, high adhesion, high durability, high volume stability and good synergistic deformation ability and can work well with steel.

[0007] To achieve the above purpose, the technical scheme disclosed by the present application is as follows: a high-toughness high-adhesion C70 strength fiber concrete comprises the following raw materials in mass fraction:

[0008] cement 350-360 parts, river sand 723 parts, gravel 1010 parts, fly ash 105-112 parts, straw ash 45-55 parts, silica fume 14-17 parts, nano silicon 2-3.5 parts, water 155-160 parts, water reducing agent 7.5-8.5 parts, activator 12-13 parts, defoaming agent 1.8-2.1 parts, shrinkage reducing agent 6.8-7.8 parts, ramie fiber 4.7-4.9 parts, basalt fiber 7.9-8.1 parts, and CaCO3 whisker 17.3-17.5 parts.

[0009] Further, the cement is P·O42.5R grade ordinary portland cement, and a cement variety with good compatibility with polycarboxylate superplasticizer is selected.

[0010] The river sand is selected to be medium-coarse river sand with good gradation, and the fineness modulus is 2.8-3.0.

[0011] The gravel is selected to be artificial gravel mainly of limestone with good gradation, dense hardness and rough surface, and the particle size range is 5-15 mm, and the gradation is according to continuous particle size.

[0012] The fly ash is high-quality fly ash of power plant grade I, with 45 mu m square hole sieve residue not more than 12%, water demand ratio not more than 95%, and specific surface area greater than 400 m 2 / kg.

[0013] The straw ash is obtained by burning stems of mature corn straw at a temperature of 600-820 DEG C, then removing potassium, and then grinding for 20 min by using a ball mill, with silica content greater than 82.3%, average particle size of 6-15 mu m, and specific surface area greater than 10 m 2 / g.

[0014] Further, the potassium removal treatment method comprises the following steps:

[0015] 1) the straw ash is placed in distilled water and stirred and soaked, then placed, and after the upper clear liquid is poured out, distilled water is added for stirring and soaking, and the process is repeated for more than 5 times, and the soaking time lasts for one week;

[0016] 2) after the upper clear liquid is poured out for the last time, the distilled water is heated to 90 DEG C and kept for 15-20 min, and then distilled water is added for soaking, and step 1) is repeated;

[0017] 3) steps 1) and 2) are repeated twice in sequence;

[0018] 4) finally, 60 DEG C is kept for 2 h, the upper clear liquid is poured out, and then dried for standby use.

[0019] The silica ash has silica content greater than 90%, average particle size of 0.1 mu m-0.3 mu m, and specific surface area greater than 20 m 2 / g;

[0020] The nano-silicon is high-purity nano-silicon dioxide prepared by a gas phase method, with purity greater than 99%, average particle size of 10 nm-40 nm, and specific surface area greater than 130 m 2 / g.

[0021] The water reducing agent is a polycarboxylic acid type high-performance water reducing agent, with solid content of 20%, water reducing rate of more than 30%, and no adverse effect on the compressive strength of concrete.

[0022] The shrinkage reducing agent is selected from SU-SRA type shrinkage reducing agent.

[0023] The defoaming agent is Liji X-2756 high-efficiency concrete defoaming agent.

[0024] The activator is an organic-inorganic composite activator, which is compounded according to the following mass percentage of raw materials:

[0025] 50-58% of dihydrate gypsum, 40-48% of calcium chloride, and 1.5-2% of triethanolamine.

[0026] The ramie fiber is alkali-treated and dried, and the length is 40-50mm, the diameter is 30-40um, the tensile strength is greater than or equal to 1000MPa, the elastic modulus is greater than or equal to 11.4GPa, the elongation at break reaches 8.9%, and the specific gravity is 1.54-1.55g / cm 3 , has good hydrophilicity, high holding force and acid and alkali resistance.

[0027] The basalt fiber has a length of 12mm, a diameter of 7-15um, a tensile strength greater than or equal to 3000MPa, an elastic modulus greater than or equal to 91GPa, and a specific gravity of 2.63-2.65g / cm 3 ;

[0028] The CaCO3 whisker has a length of 20-30um, a diameter of 0.5-2um, a tensile strength greater than or equal to 3000MPa, an elastic modulus greater than or equal to 410GPa, and a specific gravity of 2.86g / cm 3 .

[0029] The application further discloses a preparation method of the high-toughness and high-bonding C70-strength fiber concrete.

[0030] 1) 7.5-8.5 parts of a water reducing agent is added to two-thirds of the total water, and the mixture is recorded as mixed solution 1; 6.8-7.8 parts of a shrinkage reducing agent and 1.8-2.1 parts of an antifoaming agent are added to one-third of the total water, and the mixture is recorded as mixed solution 2; the total water is 155-160 parts;

[0031] 2) 4.7-4.9 parts of the ramie fiber, 1010 parts of the gravel, 723 parts of the river sand, 350-360 parts of the cement, 105-112 parts of the fly ash, 45-55 parts of the straw ash, 14-17 parts of the silica fume, 2-3.5 parts of the nano silicon, 7.9-8.1 parts of the basalt fiber and 17.3-17.5 parts of the CaCO3 whisker are evenly divided into three parts according to the mass fraction, then one part of the ramie fiber, the basalt fiber and the CaCO3 whisker are evenly spread in a disc-type mixer, and then one part of the gravel, the river sand, the cement, the fly ash, the straw ash, the silica fume and the nano silicon are sequentially placed in the disc-type mixer and stirred for 1min;

[0032] 3) the other two parts of the materials in step 2) are also added to the disc-type mixer in the same way and stirred uniformly;

[0033] 4) then the mixed solution 1 in step 1) is added to the disc-type mixer and stirred uniformly for 2-3min;

[0034] 5) 12-13 parts of an activator are further added to the disc-type mixer and stirred uniformly for 2-3min;

[0035] 6) Finally, the flowability of the mixture is observed, and the mixed solution 2 prepared in step 1) is continuously added to the pan mixer, and stirred evenly for 2-3 min, and after 3 min, stirred again for 2-3 min until the mixture is uniform, and then discharged, to obtain the prepared concrete mixture; and the concrete is molded and cured.

[0036] The molding and curing method of the concrete prepared by the preparation method:

[0037] Standard curing: the concrete mixture is molded and vibrated in a cast iron mold, and is left to stand in a standard curing room with a temperature of 20±2 DEG C and a relative humidity of greater than or equal to 95% for 1-2 days, and then is demolded and cured in the standard curing room until the required curing period.

[0038] The present application overcomes the problems of ordinary concrete, such as brittleness, low toughness, poor durability, and poor bonding performance with steel, and uses market-available materials, adopts an improved concrete layered mixing process, considers the required amount and ratio of each cementitious material for a specific concrete strength grade, and the number and size distribution of cracks in the cement matrix under the corresponding ratio, and based on multi-scale crack grading control and continuous particle size grading design of cementitious materials, a high-toughness and high-bonding C70-strength fiber concrete is prepared by adding ramie fibers, basalt fibers, CaCO3 whiskers, fly ash, straw ash, silica fume, nano-silica, and other active mineral admixtures with different particle size ranges, and water reducing agents, activators, and other chemical admixtures. The ramie fibers have water storage function and toughening effect, can play an "internal curing" role in the hydration process of the concrete, and can promote the hydration process of the cementitious material. Meanwhile, the basalt fibers and CaCO3 whiskers are used in combination to bridge the cracks of different scales in the concrete, effectively inhibit the development of the cracks, and enhance the toughness of the concrete. In addition, the mineral admixtures with different particle sizes, including fly ash, straw ash, silica fume, and nano-sized nano-silica, on the one hand, form a continuous particle size grading among the cementitious materials, so that the micro-aggregate filling effect can be more effectively played, and on the other hand, the mineral admixtures can play the effect of pozzolanic and superposition, improve the hydration products of the concrete, thereby reducing the pore size and the number of harmful pores, and improving the compactness of the concrete, so that the bonding interface between the concrete and the steel is more compact, the bonding force is further improved with the improvement of the morphology of the hydration products, and meanwhile, the cohesion between the concrete matrix and the fiber materials is enhanced, so that the fibers can synergistically act to further improve the toughness of the concrete, and effectively reduce the Cl - , SO4 2-The application can improve the durability of concrete by preventing the invasion of harmful ions such as CO2, and improving the pore structure of concrete, so that the internal structure of concrete is more compact, and the hydration shrinkage and crack development of different scales under stress are inhibited, and finally a new type of fiber concrete material with high toughness, high bonding performance, high strength and high durability is prepared.

[0039] Compared with the prior art, the application has the following beneficial effects:

[0040] 1) The ramie fiber used in the application is a long fiber with a length of 40-50 mm, which has high tensile strength, high elastic modulus and high toughness, and can effectively inhibit the formation and development of macro cracks in concrete under complex stress state; the natural hydrophilicity of the ramie fiber makes its surface have strong gripping force, and has good bonding capacity with the cement matrix, and in addition, the long fiber has sufficient anchoring length, which can effectively prevent the fiber from being pulled out and prevent the further development of cracks when the concrete cracks, and the bridging effect of the fiber can increase the deformation and energy consumption capacity of the concrete; in addition, the ramie fiber has a unique fiber cavity structure and a large specific surface area, and the cavity structure can store part of the water, which plays a role of "internal curing", and promotes the hydration process of the concrete. Therefore, the ramie fiber can improve the mechanical properties and durability such as crack resistance, impermeability and freeze-thaw resistance of the concrete.

[0041] 2) The basalt fiber and CaCO3 whisker used in the application have high strength and high elastic modulus, and the length is 12 mm and 20-30 microns respectively, which can effectively inhibit the formation and development of cracks caused by factors such as plastic shrinkage, dry shrinkage and temperature change of concrete, and work together with the ramie fiber to play a bridging effect, and can control the development of cracks of different scales in concrete, and can effectively improve the strength, toughness, deformation performance and durability of concrete; in addition, when the application is used in steel reinforced concrete composite structure, the three kinds of fibers are uniformly dispersed in the concrete to form a three-dimensional network structure, which effectively restrains the crack development of the surrounding concrete when the steel is stressed, forms a "ring constraint effect" on the steel, effectively improves the friction and mechanical interlocking force between the steel and the concrete, and further enhances the bonding force between the concrete and the steel, so that the concrete and the steel can work better together.

[0042] 3) The present application takes into account that potassium ions in straw crops are mainly enriched in new leaves and spores, and the content in mature stems is low, and the potassium ion content of different types of straw crops is different, and the mature stems of corn straw with low potassium ion content are burned at a certain temperature, and then the potassium and sodium are treated by a simple and easy, low-cost potassium removal method, which can effectively prevent the occurrence of alkali aggregate reaction in concrete, and the straw ash obtained after grinding after potassium removal treatment contains more than 82.3% of silicon dioxide, and a certain amount of active Al and Fe oxides, which has high pozzolanic activity, the straw ash particles are small (average particle size is 6-15 μm), and the porous and network structure inside the straw ash particles makes the specific surface area large, which can reach 10 m 2 / g. The incorporation of straw ash can make the cementitious material particles more uniform and well-graded, and can play a filling and compacting effect, thereby increasing the adhesion of the concrete; in addition, since the straw ash has similar pozzolanic activity as silica fume, it can replace part of the silica fume and react with Ca(OH)2 in the concrete system to form dense and hard hydrated calcium sulphoaluminate and more stable C-S-H gel, thereby improving the flexural strength, compressive strength, splitting tensile strength and durability of the concrete; finally, as an agricultural waste, the straw ash can be treated and used as a building material to replace part of the cement, which can reduce the CO2 emissions during the straw burning and cement production process, thereby reducing the cost of concrete and realizing the reuse of agricultural waste, and achieving the purpose of energy saving and environmental protection.

[0043] 4) The fly ash, straw ash, silica fume, and nano-silica added in the present application have different particle size ranges than cement, forming a relatively continuous cementitious material particle grading, which can better play the micro-aggregate filling effect, and at the same time, the fly ash, straw ash, silica fume and nano-silica produce "superposition effect", further promoting the hydration of the cementitious material, and converting more hydration products into C-S-H gel, improving the pore structure and adhesion of the concrete, in addition, nano-silica can enter smaller pores, and its surface has more unsaturated bonds and larger surface energy, which makes the hydration products, especially Ca(OH)2, rapidly gather on its surface to react, thereby promoting the growth of C-S-H gel with it as the core, limiting the generation of harmful crystals, strengthening the interface structure of the cement matrix, and further improving the flexural strength, compressive strength, splitting tensile strength, toughness, adhesion and durability of the concrete.

[0044] 5) The shrinkage reducing agent used in the present application can reduce the surface tension of water in the capillary pores of the concrete, making the concrete structure dense, thereby controlling the volume shrinkage, dry shrinkage and plastic shrinkage of the concrete during the early hardening stage, further improving the crack resistance and impermeability of the concrete, and enhancing the durability of the concrete.

[0045] 6) The activator in this invention is an organic-inorganic composite activator, which consists of gypsum dihydrate, calcium chloride, and triethanolamine working together to promote the formation of ettringite, giving concrete containing fly ash, silica fume, nano-silica, and straw ash a certain degree of micro-expansion and improving the shrinkage performance of concrete. The composite activator depolymerizes the glassy network structure on the surface of fly ash, thereby activating the potential activity of fly ash. This enhances the corrosion effect of the three-dimensional glassy structure with aluminosilicate as the main hydration component during fly ash hydration, increases the kinetics of the forward hydration reaction, generates more CSH gel and hydrated calcium aluminate crystals, and promotes the participation of fly ash in the early hydration process. The activating effect of gypsum dihydrate on mineral admixtures is reflected in: SO₂ 4- The gel on the surface of fly ash particles and AlO dissolved in the liquid phase 2- The reaction produces hydrated calcium sulfoaluminate AFt; additionally, SO4 2- It can also displace some of the SiO2 in hydrated calcium silicate. 2- The displaced SiO2 2- The outer layer is also related to Ca 2+ The process generates hydrated calcium silicate, which continuously activates the fly ash, providing Ca... 2+ Calcium chloride reacts with SiO2, Fe2O3, and Al2O3 in fly ash, silica fume, nano-silica, and straw ash to form hydrated calcium silicate, hydrated calcium ferrite, and hydrated calcium aluminate. The activation of mineral admixtures by calcium chloride mainly occurs by increasing the Ca content in the hydration system. 2+ This is achieved through concentration, the formation of hydrated aluminochloride gel phase, and hydrated calcium aluminate. In addition, calcium chloride, as a strong electrolyte, can also supplement the calcium required for the sulfate activation process of fly ash and the reactions of silica fume, straw ash, and nano-silica. 2+ Triethanolamine, as an organic fly ash activator, can complex the Fe and Al phases in fly ash during hydration, promoting the dissolution of fly ash particles and further hydrating the active substances in the fly ash. The synergistic effect between gypsum dihydrate, calcium chloride, and triethanolamine can fully activate the activity of mineral admixtures, accelerate the hydration rate of cementitious materials in the system, promote the formation of hydration products, and thus improve the strength and durability of concrete.

[0046] 7) The present invention adopts a layered mixing method and determines the maximum particle size of crushed stone through experiments. This method can disperse long fibers and aggregates evenly to the greatest extent, avoiding interference between long fibers and coarse aggregates and preventing fiber agglomeration, which would result in large pores in the cement matrix and even "honeycomb surface" phenomenon.

[0047] The above measures can effectively improve the compressive strength, toughness, deformation capacity, durability and the like of the concrete, and enhance the bonding strength and the synergic deformation capacity between the concrete and the steel shape. The high-toughness high-bonding C70 strength fiber concrete prepared by the method has the following advantages: the different types of cementitious materials in the concrete are uniformly distributed from large to small in size, the micro-aggregate filling effect of each cementitious material is fully played, the hydration products of the cementitious material can also be densely stacked, the pore structure of the concrete is further improved, the multi-scale fibers are uniformly dispersed, the development of cracks of different sizes is effectively inhibited, and therefore the concrete has high toughness and excellent durability, has good bonding performance with the steel shape, the deformation capacity is further improved, and the synergism with the steel shape is enhanced. The 28d cubic compressive strength of the fiber concrete is not less than 71.89 MPa, the flexural strength is not less than 20.61 MPa, the splitting tensile strength is not less than 8.96 MPa, the bonding strength with the steel shape is not less than 4.91 MPa, and the chloride ion migration coefficient is not more than 64*10 -14 m 2 / s. The high-performance fiber concrete with high volume stability, high durability and high toughness is prepared, raw materials are easy to obtain, the preparation process is simple, meets the requirements of sustainable development and modern green building material application and popularization, and is a new type of green and environment-friendly high-performance fiber concrete material. DETAILED DESCRIPTION

[0048] The advantages of the present application will be further described in detail by combining with specific embodiments and examples, so that the advantages of the present application are more easily understood by those skilled in the art, but are not used to limit the protection scope of the present application.

[0049] The high-toughness high-bonding C70 strength fiber concrete is prepared by the following method:

[0050] 1) 7.5-8.5 parts by mass of a water reducing agent is added to two-thirds of the total water, and is recorded as mixed solution 1; 6.8-7.8 parts by mass of a shrinkage reducing agent and 1.8-2.1 parts by mass of an antifoaming agent are added to one-third of the total water, and are recorded as mixed solution 2; the total water is 155-160 parts;

[0051] 2) Divide 4.7-4.9 parts of ramie fiber, 1010 parts of crushed stone, 723 parts of river sand, 350-360 parts of cement, 105-112 parts of fly ash, 45-55 parts of straw ash, 14-17 parts of silica fume, 2-3.5 parts of nano-silica, 7.9-8.1 parts of basalt fiber, and 17.3-17.5 parts of CaCO3 whiskers into three equal parts by mass fraction. Then, evenly spread one part of ramie fiber, basalt fiber, and CaCO3 whiskers in a disc mixer. Then, place one part of crushed stone, river sand, cement, fly ash, straw ash, silica fume, and nano-silica into the disc mixer in sequence and mix for 1 minute.

[0052] 3) Add the other two portions of ingredients from step 2) to the disc mixer in the same way and mix well;

[0053] 4) Then add the mixed solution 1 from step 1) to the disc mixer and stir evenly for 2-3 minutes;

[0054] 5) Add 12-13 parts of activator to the disc mixer and stir evenly for 2-3 minutes;

[0055] 6) Finally, observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer. Stir evenly for 2-3 minutes, and after a 3-minute interval, stir for another 2-3 minutes until the mixture is uniform. Discharge the mixture to obtain the prepared concrete mixture; and then shape and cure it.

[0056] The method for forming and curing concrete according to the present invention is as follows:

[0057] The concrete mixture is poured into a cast iron mold and compacted using a vibrating table. Then, a vibrator is used to vibrate along the outer wall of the mold to remove excess air bubbles from the concrete mixture. After molding, the test block is placed in an environment with a temperature of 20±2℃, and a moistened geotextile is placed on the surface of the test block. After standing for 1 day, the mold is removed, and then the test block is cured in a standard curing room at a temperature of 20±2℃ and a relative humidity of ≥95% until the required age is reached.

[0058] in:

[0059] The cement used is commercially available P·O42.5R grade ordinary Portland cement, which has good compatibility with polycarboxylate superplasticizer.

[0060] The river sand used was medium-coarse river sand with a fineness modulus of 2.9 and an apparent density of 2.59 g / cm³. 3 The bulk density is 1.48 g / cm³. 3 .

[0061] The crushed stone used is dense, hard, and rough-surfaced limestone with a particle size of 5-15 mm, uniform and continuous gradation, and an apparent density of 2.7 g / cm³.3 The bulk density is 1.51 g / cm 3 .

[0062] The fly ash used is high-quality grade I fly ash from a power plant, with a sieve residue of no more than 12% on a 0.045 mm square hole screen, a specific surface area of more than 400 m 2 / kg, and an average particle size in the range of 15-30 μm.

[0063] The straw ash used is obtained by burning the stems of mature corn straw at a temperature of 600-820°C, then treating to remove potassium, and then grinding for 20 min using a ball mill, and has a silicon dioxide content of more than 82.3%, an average particle size of 6-15 μm, and a specific surface area of more than 10 m 2 / g.

[0064] The method for removing potassium is as follows:

[0065] 1) The straw ash is placed in distilled water and stirred and soaked, then left to stand, the supernatant is poured off, and then distilled water is added again, stirred and soaked, and this process is repeated for more than 5 times, with the soaking time lasting for one week;

[0066] 2) After the supernatant is poured off for the last time, the distilled water is heated to 90°C and held for 15-20 min, then distilled water is added again for soaking, and step 1) is repeated;

[0067] 3) Steps 1) and 2) are repeated again in order twice;

[0068] 4) Finally, 60°C is held for 2 h, the supernatant is replaced with distilled water, and then dried for use.

[0069] The silica ash used has a silicon dioxide content of more than 90%, an average particle size of 0.1 μm-0.3 μm, and a specific surface area of more than 20 m 2 / g;

[0070] The nano-silicon used is high-purity nano-silicon dioxide obtained by a gas phase method, with a purity of more than 99%, an average particle size of 10 nm-40 nm, and a specific surface area of more than 130 m 2 / g.

[0071] The water reducing agent used is a polycarboxylic acid type high-performance water reducing agent, with a solid content of 20%, a pH value of 8.0, a water reducing rate of more than 30%, and a 7d / 28d compressive strength ratio of no less than 150%.

[0072] The shrinkage reducing agent used is an SU-SRA type shrinkage reducing agent.

[0073] The defoaming agent used is a Leqi X-2756 high-efficiency concrete defoaming agent.

[0074] The excitation agent used is an organic-inorganic composite excitation agent, which is compounded according to the following mass percentages of raw materials: gypsum dihydrate 50-58%, calcium chloride 40-48%, and triethanolamine 1.5-2%.

[0075] The ramie fiber used is alkali-treated and dried refined fiber, with a length of 40-50 mm, a diameter of 30-40 mu m, a tensile strength of 1000 MPa or more, an elastic modulus of 11.4 GPa or more, a breaking elongation of 8.9%, and a specific gravity of 1.54-1.55 g / cm 3 .

[0076] The basalt fiber used has a length of 12 mm, a diameter of 7-15 mu m, a tensile strength of 3000 MPa or more, an elastic modulus of 91 GPa or more, and a specific gravity of 2.63-2.65 g / cm 3 ;

[0077] The CaCO3 whisker used has a length of 20-30 mu m, a diameter of 0.5-2 mu m, a tensile strength of 3000 MPa or more, an elastic modulus of 410 GPa or more, and a specific gravity of 2.86 g / cm 3 .

[0078] The following specific embodiments are given to further illustrate the preparation method of the present application.

[0079] Example 1

[0080] 1) Add 8 parts of water-reducing agent to two-thirds of the total water, denoted as mixed solution 1; add 7.5 parts of shrinkage-reducing agent and 1.9 parts of defoaming agent to one-third of the total water, denoted as mixed solution 2, with the total water being 160 parts;

[0081] 2) Divide 4.8 parts of ramie fiber, 1010 parts of gravel, 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 CaCO3 whisker into three equal parts by mass fraction, respectively. Then evenly spread one part of ramie fiber, basalt fiber, and CaCO3 whisker in a disc-type mixer. Then place one part of gravel, river sand, cement, fly ash, straw ash, silica fume, and nano silicon in the disc-type mixer in order, and stir for 1 min;

[0082] 3) Add the other two parts of materials to the disc-type mixer in the same way and stir evenly;

[0083] 4) Then add the mixed solution 1 in step 1) to the disc-type mixer and stir evenly for 2-3 min;

[0084] 5) then 12.5 parts of the activator is added into the disc mixer and stirred evenly for 2-3 minutes; wherein, the activator is compounded by the following raw materials in the following mass percentage: gypsum dihydrate 52.5%, calcium chloride 46%, triethanolamine 1.5%;

[0085] 6) finally, the flowability of the mixture is observed, the mixed solution 2 prepared in step 1) is continuously added into the disc mixer and stirred evenly for 2-3 minutes, after 3 minutes, the mixture is stirred again for 2-3 minutes until the mixture is uniform, and then the mixture is discharged, thus the prepared concrete mixture is obtained; and the concrete mixture is molded and cured.

[0086] The molding and curing method of the concrete is as follows:

[0087] The concrete mixture is poured into an iron mold for molding, a vibration table is used for compaction, and then a vibration rod is used for contact vibration along the outer wall of the mold to discharge the excess bubbles in the concrete mixture; after molding, the test block is placed in an environment with a temperature of 20±2℃, a wet geotextile is covered on the surface of the test block, and the test block is placed for 1 day, then the mold is removed, and the test block is cured in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% until the required curing period.

[0088] Example 2

[0089] 1) 8.5 parts of the water reducing agent is added into two-thirds of the total water, which is recorded as mixed solution 1; 7.8 parts of the shrinkage reducing agent and 2.1 parts of the defoaming agent are added into one-third of the total water, which is recorded as mixed solution 2, and the total water is 155 parts;

[0090] 2) 4.9 parts of the ramie fiber, 1010 parts of the gravel, 723 parts of the river sand, 360 parts of the cement, 109 parts of the fly ash, 55 parts of the straw ash, 17 parts of the silica fume, 2 parts of the nano silicon, 8.1 parts of the basalt fiber, and 17.5 parts of the CaCO3 whisker are evenly divided into three parts according to the mass fraction, then one part of the ramie fiber, the basalt fiber, and the CaCO3 whisker are evenly spread in the disc mixer, and then one part of the gravel, the river sand, the cement, the fly ash, the straw ash, the silica fume, and the nano silicon are sequentially placed in the disc mixer and stirred for 1 minute;

[0091] 3) the other two parts of the materials are also added into the disc mixer and stirred evenly in the same way;

[0092] 4) then the mixed solution 1 in step 1) is added into the disc mixer and stirred evenly for 2-3 minutes;

[0093] 5) then 13 parts of the activator is added into the disc mixer and stirred evenly for 2-3 minutes; wherein, the activator is compounded by the following raw materials in the following mass percentage: gypsum dihydrate 55.2%, calcium chloride 43%, triethanolamine 1.8%;

[0094] 6) Finally, the flowability of the mixture is observed, and the mixed solution 2 prepared in step 1) is continuously added to the disc mixer, and stirred uniformly for 2-3 min, and after 3 min, stirred again for 2-3 min until the mixture is uniform, and then discharged, to obtain the prepared concrete mixture; and then molded and cured.

[0095] The molding and curing method of the concrete is as follows:

[0096] The concrete mixture is poured into an iron mold for molding, a vibration table is used for compaction, and then a vibration rod is used for contact vibration along the outer wall of the mold to discharge the excess bubbles in the concrete mixture; after molding, the test block is placed in an environment with a temperature of 20±2℃, and a wet geotextile is covered on the surface of the test block, and then placed for 1d, and then demolded, and then cured in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% to the required age.

[0097] Example 3

[0098] 1) A mass fraction of 8 parts of water reducing agent is added to two-thirds of the total water, which is recorded as mixed solution 1; 7.5 parts of shrinkage reducing agent and 1.9 parts of defoaming agent are added to one-third of the total water, which is recorded as mixed solution 2, and the total water is 160 parts;

[0099] 2) 4.7 parts of ramie fiber, 1010 parts of gravel, 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 CaCO3 whisker are each divided into three equal parts by mass fraction, and then one part of ramie fiber, basalt fiber, and CaCO3 whisker is evenly spread in the disc mixer, and then one part of gravel, river sand, cement, fly ash, straw ash, silica fume, and nano silicon is placed in the disc mixer in order, and stirred for 1 min;

[0100] 3) The other two parts of materials are also added to the disc mixer in the same way and stirred uniformly;

[0101] 4) Then, the mixed solution 1 in step 1) is added to the disc mixer, and stirred uniformly for 2-3 min;

[0102] 5) Then, 12 parts of activator are added to the disc mixer, and stirred uniformly for 2-3 min; wherein, the activator is compounded according to the mass percentage of the raw materials: gypsum dihydrate 58%, calcium chloride 40%, and triethanolamine 2%;

[0103] 6) Finally, the flowability of the mixture is observed, and the mixed solution 2 prepared in step 1) is continuously added to the disc-type mixer, and stirred uniformly for 2-3 min, and after 3 min, stirred again for 2-3 min until the mixture is uniform, and then discharged, thereby obtaining the prepared concrete mixture; and then molded and cured.

[0104] The molding and curing method of the concrete is as follows:

[0105] The concrete mixture is poured into an iron mold for molding, and a vibration table is used for compaction, and then a vibration rod is used for contact vibration along the outer wall of the mold to remove the excess bubbles in the concrete mixture; after molding, the test block is placed in an environment with a temperature of 20±2℃, and a wet geotextile is covered on the surface of the test block, and then placed for 1 d, and then demolded, and then cured in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% to the required age.

[0106] Example 4

[0107] 1) A mass fraction of 8.5 parts of a water reducing agent is added to two-thirds of the total water, and is recorded as mixed solution 1; a weighed 6.8 parts of a shrinkage reducing agent and 1.8 parts of an antifoaming agent are added to one-third of the total water, and is recorded as mixed solution 2, and the total water is 157 parts;

[0108] 2) 4.8 parts of ramie fibers, 1010 parts of gravel, 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 fibers, and 17.4 parts of CaCO3 whiskers are each divided into three equal parts according to the mass fraction, and then one part of the ramie fibers, the basalt fibers, and the CaCO3 whiskers are uniformly spread in a disc-type mixer, and then one part of the gravel, the river sand, the cement, the fly ash, the straw ash, the silica fume, and the nano silicon are sequentially placed in the disc-type mixer and stirred for 1 min;

[0109] 3) The other two parts of materials are also added to the disc-type mixer in the same way and stirred uniformly;

[0110] 4) Then, the mixed solution 1 in step 1) is added to the disc-type mixer and stirred uniformly for 2-3 min;

[0111] 5) Then, 12.3 parts of an activator are added to the disc-type mixer and stirred uniformly for 2-3 min; wherein, the activator is compounded according to the following mass percentage of raw materials: gypsum dihydrate 55.2%, calcium chloride 43%, and triethanolamine 1.8%;

[0112] 6) Finally, the flowability of the mixture is observed, and the mixed solution 2 prepared in step 1) is continuously added to the disc mixer, and stirred uniformly for 2-3 min, and after 3 min, stirred again for 2-3 min until the mixture is uniform, and then discharged, thereby obtaining the prepared concrete mixture; and then molded and cured.

[0113] The molding and curing method of the concrete is as follows:

[0114] The concrete mixture is poured into an iron mold for molding, and a vibration table is used for compaction, and then a vibration rod is used for contact vibration along the outer wall of the mold to remove the excess bubbles in the concrete mixture; after molding, the test block is placed in an environment with a temperature of 20±2℃, and a wet geotextile is covered on the surface of the test block, and then placed for 1 d, and then demolded, and then cured in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% to the required age.

[0115] Example 5

[0116] 1) A mass fraction of 7.5 parts of a water reducing agent is added to two-thirds of the total water, and is recorded as mixed solution 1; a weighed 7.8 parts of a shrinkage reducing agent and 1.9 parts of an antifoaming agent are added to one-third of the total water, and is recorded as mixed solution 2, and the total water is 155 parts;

[0117] 2) 4.9 parts of ramie fibers, 1010 parts of gravel, 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 fibers, and 17.4 parts of CaCO3 whiskers are each divided into three equal parts according to the mass fraction, and then one part of the ramie fibers, the basalt fibers, and the CaCO3 whiskers are uniformly spread in the disc mixer, and then one part of the gravel, the river sand, the cement, the fly ash, the straw ash, the silica fume, and the nano silicon are sequentially placed in the disc mixer and stirred for 1 min;

[0118] 3) The other two parts of materials are also added to the disc mixer in the same way and stirred uniformly;

[0119] 4) Then, the mixed solution 1 in step 1) is added to the disc mixer and stirred uniformly for 2-3 min;

[0120] 5) Then, 12.8 parts of an activator are added to the disc mixer and stirred uniformly for 2-3 min; wherein, the activator is compounded according to the following mass percentage of raw materials: gypsum dihydrate 55.2%, calcium chloride 43%, and triethanolamine 1.8%;

[0121] 6) Finally, the flowability of the mixture is observed, and the mixed solution 2 prepared in step 1) is continuously added to the disc-type mixer, and stirred evenly for 2-3 min, and after 3 min, stirred again for 2-3 min until the mixture is uniform, and then discharged, thereby obtaining the prepared concrete mixture; and molding and curing.

[0122] The molding and curing method of the concrete is as follows:

[0123] The concrete mixture is poured into an iron mold for molding, and a vibration table is used for compaction, and then a vibration rod is used for contact vibration along the outer wall of the mold to remove the excess bubbles in the concrete mixture; after molding, the test block is placed in an environment with a temperature of 20±2℃, and a wet geotextile is covered on the surface of the test block, and then placed for 1d, and then demolded, and then cured in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% to the required age.

[0124] Example 6

[0125] 1) A mass fraction of 7.5 parts of water reducing agent is added to two-thirds of the total water, which is recorded as mixed solution 1; and 7 parts of shrinkage reducing agent and 2 parts of defoaming agent are added to one-third of the total water, which is recorded as mixed solution 2, and the total water is 157 parts;

[0126] 2) 4.7 parts of ramie fiber, 1010 parts of gravel, 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 CaCO3 whisker are each divided into three equal parts by mass fraction, and then one part of the ramie fiber, basalt fiber, and CaCO3 whisker is evenly spread in the disc-type mixer, and then one part of the gravel, river sand, cement, fly ash, straw ash, silica fume, and nano silicon is sequentially placed in the disc-type mixer and stirred for 1 min;

[0127] 3) The other two parts of the materials are also added to the disc-type mixer in the same way and stirred evenly;

[0128] 4) Then, the mixed solution 1 in step 1) is added to the disc-type mixer and stirred evenly for 2-3 min;

[0129] 5) Then, 12 parts of the activator are added to the disc-type mixer and stirred evenly for 2-3 min; wherein, the activator is compounded according to the following mass percentage of raw materials: gypsum dihydrate 52.5%, calcium chloride 46%, and triethanolamine 1.5%.

[0130] 6) Finally, the flowability of the mixture is observed, and the mixed solution 2 prepared in step 1) is continuously added to the disc-type mixer, and stirred evenly for 2-3 min, and after 3 min, stirred again for 2-3 min until the mixture is uniform, and then discharged, thereby obtaining the prepared concrete mixture; and molding and curing.

[0131] The forming and curing method of the concrete is as follows:

[0132] The concrete mixture is poured into a cast iron mold for forming, a vibrating table is used for tamping, then a vibrating rod is used for contact vibration along the outer wall of the mold to discharge the excess bubbles in the concrete mixture; after forming, the test block is placed in an environment with a temperature of 20±2℃, a wet geotextile is covered on the surface of the test block, and the test block is left for 1 day, then the mold is removed, and the test block is cured in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% to the required age.

[0133] The following gives a comparison between the comparative example and the embodiment of the present application to further illustrate the effect of the present application.

[0134] The comparative example is a common high-strength concrete without using continuous grading design of cementitious particles and without adding fibers.

[0135] The proportioning is as follows: cement 524 parts, river sand 723 parts, gravel 1010 parts, water 153 parts, and water reducing agent 7 parts.

[0136] The preparation method is as follows:

[0137] 1) 7 parts of water reducing agent is added to two-thirds of the total water, which is recorded as mixed solution 1; the total water is 153 parts;

[0138] 2) one part of 1010 parts of gravel, 723 parts of sand, and 524 parts of cement is placed in a mixer and stirred for 1 min;

[0139] 3) then, the mixed solution 1 in step 1) is added to the mixer, and stirred uniformly for 2-3 min;

[0140] 4) after 1 min, the mixture is stirred uniformly for another 2-3 min;

[0141] 5) finally, the fluidity of the mixture is observed, the remaining one-third of the water is added to the mixer, and stirred uniformly for 2-3 min, after 3 min, the mixture is stirred again for 2-3 min until the mixture is uniform, and then discharged, to obtain the prepared concrete mixture; and the mixture is formed and cured.

[0142] The forming and curing method of the concrete of the comparative example is as follows:

[0143] The concrete mixture is poured into a cast iron mold for forming, a vibrating table is used for tamping, then a vibrating rod is used for contact vibration along the outer wall of the mold to discharge the excess bubbles in the concrete mixture; after forming, the test block is placed in an environment with a temperature of 20±2℃, a wet geotextile is covered on the surface of the test block, and the test block is left for 1 day, then the mold is removed, and the test block is cured in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% to the required age.

[0144] The performance test results of the high toughness and high bonding C70 strength fiber concrete prepared in Examples 1-6 and the comparative concrete are shown in Table 1.

[0145] Table 1 Performance comparison of Examples 1-6 and the comparative example

[0146]

[0147] As shown in Table 1, the high toughness and high bonding C70 strength fiber concrete prepared in the present application meets the required compressive and bending strength when the component is under load, and ensures the bonding strength of the cooperative work with the steel. The 28d cubic compressive strength is not less than 71.89 MPa, the flexural strength is not less than 20.61 MPa, the splitting tensile strength is not less than 8.96 MPa, the bonding strength between the steel and the concrete is not less than 4.91 MPa, and the chloride ion migration coefficient is not more than 64x10 -14 m 2 / s. Example 1 is the optimal mixing ratio, the cementitious material particle size distribution is optimal, and the fiber content is optimal. Under the C70 strength grade, there is sufficient toughness and bonding to improve the cooperative work ability of the steel and the concrete, and it can be applied as a modern green building material.

[0148] The above description is only the embodiment of the present application, which is further detailed in combination with the specific optimized implementation mode, and cannot limit the protection scope of the present application. The related technicians in the field should make simple changes or substitutions by using the disclosed content and method of the present application or without departing from the concept of the present application, which should be considered within the protection scope of the present application. The protection scope of the present application should be subject to the protection scope defined by the disclosed claims.

Claims

1. A high-ductility high-cohesion C70-strength fiber concrete, characterized by, The concrete comprises raw materials in the following mass fractions: cement 360 parts, river sand 723 parts, gravel 1010 parts, fly ash 110 parts, straw ash 50 parts, silica fume 16 parts, nano-silicon dioxide 3 parts, water 160 parts, water reducing agent 8 parts, activator 12.5 parts, defoaming agent 1.9 parts, shrinkage reducing agent 7.5 parts, ramie fiber 4.8 parts, basalt fiber 8.1 parts, CaCO3 whisker 17.4 parts; The ramie fiber is alkali treated and dried, the length is 40-50mm, the diameter is 30-40μm, the tensile strength is greater than or equal to 766MPa, the elastic modulus is greater than or equal to 9.1GPa, the breaking elongation reaches 8.9%, and the specific gravity is 1.54-1.55g / cm 3 ; The basalt fibers are 12 mm in length, 7 μm-15 μm in diameter, have a tensile strength ≥3000 MPa, an elastic modulus ≥91 GPa, and a specific gravity of 2.63-2.65 g / cm³. 3 ; The CaCO3 whisker has a length of 20-30 μm, a diameter of 0.5-2 μm, a tensile strength of ≥3000 MPa, an elastic modulus of ≥410 GPa, and a specific gravity of 2.86 g / cm 3 ; The straw ash is prepared by burning mature stem of corn straw at a temperature of 600-820 DEG C, removing potassium, and then grinding for 20 min by using a ball mill; the silica content is greater than 82.3%, the average particle size is 6-15 mu m, and the specific surface area is greater than 10 m 2 / g. The nano-silica is high-purity nano-silica prepared by a gas phase method, with purity greater than 99%, average particle size of 10-40 nm, and specific surface area greater than 130 m 2 / g. the activator is an organic-inorganic composite activator, and the composite activator is compounded from raw materials in the following mass percentages: dihydrated gypsum 52.5%, calcium chloride 46%, triethanolamine 1.5%; The 28d cube compressive strength of the fiber concrete with C70 strength is 75.88MPa, the flexural strength is 21.78MPa, the splitting tensile strength is 9.54MPa, the bonding strength between the fiber concrete and the steel is 5.22MPa, and the chloride ion migration coefficient is 59×10 -14 m 2 / s.

2. The high-ductility, high-cohesion C70-strength fiber concrete according to claim 1, characterized by, the cement is P•O42.5R grade ordinary portland cement; the river sand is medium-coarse river sand with good gradation, and the fineness modulus is 2.8-3.0; the gravel is artificial gravel mainly composed of limestone with good gradation, compactness, hardness and rough surface, and the particle size range is 5mm-15mm; The fly ash adopts high-quality I-class fly ash of power plant, the 45 μm square hole sieve residue is not more than 12%, the water demand ratio is not more than 95%, and the specific surface area should be greater than 400 m 2 / kg. the water reducing agent is a polycarboxylic acid high-performance water reducing agent with a solid content of 20%, and the water reducing rate of the water reducing agent is more than 30%.

3. The high ductility high bond C70 strength fiber reinforced concrete according to claim 1, wherein, The potassium-removing treatment method of the straw ash comprises the following steps: 1) The straw ash is stirred and soaked in distilled water, and then is left to stand. After the supernatant is poured out, distilled water is added again for stirring and soaking. The above steps are repeated more than 5 times, and the soaking time lasts for one week; 2) After the supernatant is poured out for the last time, the distilled water is heated to 90℃ for 15-20min. After the heat preservation is completed, distilled water is added again for soaking. The step 1) is repeated; 3) The steps 1)-2) are repeated twice; 4) After the last time of heat preservation at 60℃ for 2h, the supernatant is poured out, and then is dried for standby use.

4. The high ductility high bond C70 strength fiber reinforced concrete according to claim 1, wherein, The silica content of the silica fume is greater than 90%, the average particle size is 0.1-0.3 μm, and the specific surface area is greater than 20 m 2 / g.

5. A method of producing a high-ductility, high-cohesion C70-strength fiber concrete according to any one of claims 1 to 4, characterized by, The method comprises the following steps: 1) The water reducing agent with a mass fraction of 8 parts is added to two-thirds of the total water, which is recorded as mixed solution 1. The shrinkage reducing agent with a mass fraction of 7.5 parts and the defoaming agent with a mass fraction of 1.9 parts are added to the remaining one-third of the water, which is recorded as mixed solution 2. The total water is 160 parts; 2) The ramie fiber with a mass fraction of 4.8 parts, the gravel with a mass fraction of 1010 parts, the river sand with a mass fraction of 723 parts, the cement with a mass fraction of 360 parts, the fly ash with a mass fraction of 110 parts, the straw ash with a mass fraction of 50 parts, the silica fume with a mass fraction of 16 parts, the nano-silicon dioxide with a mass fraction of 3 parts, the basalt fiber with a mass fraction of 8.1 parts and the CaCO3 whisker with a mass fraction of 17.4 parts are each divided into three equal parts according to the mass fraction. Then one part of the ramie fiber, the basalt fiber and the CaCO3 whisker is evenly spread in a disc-type mixer. Then one part of the gravel, the river sand, the cement, the fly ash, the straw ash, the silica fume, the nano-silicon dioxide, the basalt fiber and the CaCO3 whisker is sequentially placed in the disc-type mixer for stirring for 1min; 3) The other two parts of the materials in the step 2) are also added to the disc-type mixer in the same way and are stirred uniformly; 4) Then the mixed solution 1 in the step 1) is added to the disc-type mixer, and is stirred uniformly for 2-3min; 5) Then the activator with a mass fraction of 12.5 parts is added to the disc-type mixer, and is stirred uniformly for 2-3min; 6) Finally, the fluidity of the mixture is observed. The mixed solution 2 prepared in the step 1) is added to the disc-type mixer, and is stirred uniformly for 2-3min. After an interval of 3min, the mixture is stirred again for 2-3min until the mixture is uniform. Then the mixture is discharged, and the prepared concrete mixture is obtained. Then the concrete mixture is shaped and maintained.

6. A molding and curing method of high-tenacity high-cohesion C70-strength fiber concrete prepared based on the preparation method of claim 5, characterized by, The standard maintenance method is adopted. The standard curing method is as follows: the concrete mixture is cast into a cast iron mold for molding and tamping, and is left to stand in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% for 1-2 days, the mold is removed, and then the concrete is cured in the standard curing room to the required age.

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