CN113185209B - High-toughness high-cohesiveness C220 ultrahigh-strength hybrid fiber concrete and preparation method thereof - Google Patents

Abstract

The invention discloses a high-toughness high-cohesiveness C220 ultrahigh-strength hybrid fiber concrete and a preparation method thereof, wherein the mixing proportion comprises the following components: and (3) cement: sand: broken stone: fly ash: straw ash: silica fume: nano silicon: water: water reducing agent: exciting agent: defoaming agent: shrinkage reducing agent: ramie fiber: basalt fiber: caCO (CaCO) ₃ Whisker: carboxyl modified polyvinyl alcohol polymer: nano titanium/graphene oxide dispersion = 535-540:735-740:880-890:70-75:90-100:100-105:4.8-5:85-90:17.5-18.5:15-15.5:2.6-3:12-13:6.7-7:12.5-12.7:19.2-19.5:21-22:36-39. By layered stirringThe materials are uniformly mixed by a mixing method, and the curing is prepared. The concrete mechanics, durability and the bonding performance between the profile steel are all obviously improved.

Description

High-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete and its preparation method

technical field

The invention belongs to the field of building materials, and is a kind of mixed ramie fiber, basalt fiber, CaCO ₃ whisker, carboxyl modified polyvinyl alcohol polymer, nano titanium/graphene oxide dispersion liquid, straw ash, fly ash, silica fume and The nano-silicon concrete has high toughness, high cohesiveness, high durability and high volume stability, and specifically relates to a high-toughness and high cohesion C220 ultra-high-strength hybrid fiber concrete and a preparation method thereof.

Background technique

In the structural design, considering the requirements of use function, component stiffness and convenient construction, it is usually necessary to use different grades of concrete for different stress situations to meet the required compressive, flexural and splitting tensile strength of the component when it is loaded. And to ensure the bond strength of concrete and steel working together. Concrete materials with different grades have different modulus of elasticity and different deformation properties. Therefore, if the strength index is too large or too small, the deformation of steel and concrete will not be coordinated when the component is stressed, resulting in the inability of the two materials to work together completely or the failure of a certain material. The mechanical properties cannot be fully exerted, resulting in material waste. Ordinary concrete and high-performance concrete have poor crack resistance and high brittleness. As the strength of concrete increases, the brittleness becomes more and more obvious. However, under high stress or complex stress conditions, it is often necessary to use specific high-strength concrete, such as In different floors of giant super high-rise structures, including bottom stress floors, reinforced floors, and industrial buildings, in super-long spans, heavy-duty structures, super-long-span bridges and their piers, and ultra-durable hydraulic structures with different spans and load-bearing requirements, components Bearing capacity, stiffness and structural use function are strictly required. Therefore, considering the bearing capacity, stiffness requirements, economic benefits, design requirements, etc., it is sometimes necessary to use concrete with a strength grade of C220. At this time, under complex stress and harsh environments, the concrete The brittle characteristics will reduce the seismic bearing capacity of components and structures, and even affect their safety and reliability. At the same time, with the gradual improvement of the mechanical properties of steel, the toughness, deformation properties and bonding properties of ordinary concrete have been difficult to meet the synergy between concrete and steel.

Silica fume has excellent particle size and pozzolanic activity, and is an important mineral admixture for the preparation of high-performance concrete, but its annual output in my country is low, only 3000t-4000t, which can only meet the needs of some high-performance concrete , limiting its extensive use. As a large agricultural country, my country's annual output of straw is more than 700 million tons, ranking first in the world. At present, only a small portion of straw is used in biomass power plants to generate electricity, while most of the straw is still piled up naturally or burned in the open, resulting in waste of resources and environmental pollution. If the straw ash produced by power plants is not properly developed and utilized, it will cause secondary pollution to the environment. With the advancement of science and technology, it is found that the straw ash prepared by incinerating corn stalks under appropriate conditions contains about 85% amorphous SiO ₂ and a certain amount of active Al ₂ O ₃ and other metal oxides, K, Na With less content, it can give full play to the pozzolanic effect and micro-aggregate filling effect, and can be used in concrete to improve mechanical properties.

Cement and mineral admixtures play a role in concrete through the hydration products generated by the hydration reaction, and the properties of the hydration products are often poor, and the formed needle-shaped and flaky hydration products are relatively brittle. In turn, the concrete matrix is more brittle, so providing a template for the hydration reaction of the cementitious material, allowing the hydrate to react in the template to form thick and dense hydration crystals, is an effective way to improve the internal structure of concrete. The template effect and nucleation effect of graphene oxide and nano-TiO ₂ materials can provide good attachment points for hydration products, making the hydration products stronger and denser, and fundamentally improving the brittleness of concrete.

Concrete and cement-based composite materials usually improve their toughness by adding fibers. Existing steel fibers and synthetic fibers are difficult to popularize in concrete engineering applications due to complex processes, high costs, and low output. Plant fiber to replace steel fiber and synthetic fiber. Ramie fiber has high cellulose content, high strength, high toughness, high acid and alkali resistance, green and pollution-free, and can effectively replace steel fiber and synthetic fiber in engineering applications. And my country is the main producing area of ramie, and the output accounts for more than 90% of the world, which makes ramie fiber easy to obtain in my country, low in price, and has great popularization and application value. At the same time, due to the presence of cracks of different sizes in concrete, adding a single fiber often cannot achieve the best toughening effect.

To sum up, from the perspective of environmental protection, cost saving, and effective use of resources, multi-level crack control and particle gradation optimization design from macro to micro are adopted, and the organic combination of them is considered to form a unified whole, so as to realize the internal control of concrete. The improvement and strengthening of the structure, the preparation of a C220 strength grade, high toughness, high adhesion, high durability, good collaborative deformation ability, and high toughness and high adhesion that can work with high-performance steel Ultra-high-strength concrete has become an urgent technical problem in this field.

Contents of the invention

The purpose of the present invention is to provide a super-long-span, heavy-duty structure, super-long-span bridge and its pier, High-toughness and high-cohesion C220 ultra-high-strength hybrid fiber concrete used in ultra-durable hydraulic structures and a preparation method thereof, the concrete has high toughness, high cohesion, high durability, high volume stability and good co-deformation Ability to work well with steel.

In order to achieve the above object, the technical solution disclosed in the present invention is: a high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete, including the following raw materials in parts by mass:

535-540 parts of cement, 735-740 parts of sand, 880-890 parts of gravel, 70-75 parts of fly ash, 90-100 parts of straw ash, 100-105 parts of silica fume, 4.8-5 parts of nano silicon, 85 parts of water -90 parts, 17.5-18.5 parts of water reducer, 15-15.5 parts of activator, 2.6-3 parts of defoamer, 12-13 parts of shrinkage reducer, 6.7-7 parts of ramie fiber, 12.5-12.7 parts of basalt fiber, CaCO ₃ 19.2-19.5 parts of whiskers, 36-39 parts of nano-titanium/graphene oxide dispersion, 21-22 parts of carboxyl-modified polyvinyl alcohol polymer.

Further, the cement is P·I62.5R grade Portland cement, and the cement variety with good compatibility with polycarboxylate water reducing agent is selected.

The fine aggregate adopts hard sand with a mass ratio of 1:1 and high-quality quartz sand with good gradation, the sand fineness modulus is 2.8-3.0, the silica content in the quartz sand is not less than 98%, and the particle size 0.3-0.6mm, density 2.62g/cm ³ ;

The crushed stones are basalt crushed stones with good grading, compactness and hardness, and rough surface, with a particle size range of 5-10mm, and are graded according to continuous particle size.

The fly ash is high-quality Class I fly ash from a power plant, and its 45μm square hole sieve residue is not more than 10%, the water demand ratio is not more than 95%, and the specific surface area should be more than 400m ² /kg.

The straw ash is obtained by incinerating the stems of mature corn stalks at a temperature of 650-820° C., followed by potassium removal treatment, and then grinding for 25 minutes with a ball mill. The silicon dioxide content is 84.1%, and the average particle size is 6 -12μm, the specific surface area is greater than 12m ² /g.

Further, the steps of the potassium-removing treatment method are as follows:

1) Put the straw ash in distilled water, stir and soak, then let it stand, pour off the supernatant and continue to add distilled water to stir and soak, repeat this process more than 5 times, and the soaking time lasts for one week;

2) After pouring out the supernatant for the last time, heat it to 90°C with distilled water and keep it warm for 15-20 minutes. After the heat preservation is over, pour out the supernatant, add distilled water to soak, and repeat step 1);

3) Repeat steps 1) and 2) twice in order;

4) Finally, keep warm at 60°C for 2 hours, pour off the supernatant, and dry for later use.

The silicon dioxide content of the silica fume is greater than 95%, the pozzolanic activity index is greater than 95%, the average particle size is 0.1 μm-0.15 μm, and the specific surface area is greater than 28m ² /g;

The nano-silicon is high-purity nano-silicon dioxide prepared by gas phase method, the purity is greater than 99%, the average particle diameter is 10nm-40nm, and the specific surface area is greater than 130m ² /g.

The water reducer is a polycarboxylate high-performance water reducer suitable for cementitious material systems with a low water-binder ratio and a high content of silica fume. The solid content is 20%, and the water reducing rate is above 38%. 7d, 28d The compressive strength ratio is not less than 180%, and has no adverse effect on the compressive strength of concrete.

The shrinkage reducer is SU-SRA type shrinkage reducer.

The defoamer uses Liqi X-2756 high-efficiency concrete defoamer.

The activator adopts an organic-inorganic composite activator, and the composite activator is compounded according to the following raw materials in mass percentage:

Dihydrate gypsum 50-58%, calcium chloride 40-48%, triethanolamine 1.5-2%.

The ramie fiber is fine-dried hemp fiber after alkali treatment and drying, the length is 40-50 mm, the diameter is 30 μm-40 μm, the tensile strength is ≥ 1000 MPa, the elastic modulus is ≥ 11.4 GPa, the elongation at break reaches 8.9%, and the specific gravity is 1.54-40 μm. 1.55g/cm ³ , with good hydrophilicity, high grip strength and acid and alkali resistance.

The basalt fiber has a length of 12 mm, a diameter of 7 μm-15 μm, a tensile strength ≥ 3000 MPa, a modulus of elasticity ≥ 91 GPa, and a specific gravity of 2.63-2.65 g/cm ³ ;

The CaCO ₃ whiskers have a length of 20 μm-30 μm, a diameter of 0.5 μm-2 μm, a tensile strength ≥ 3000 MPa, an elastic modulus ≥ 410 GPa, and a specific gravity of 2.86 g/cm ³ .

The carboxyl-modified polyvinyl alcohol polymer is an organic polymer obtained by mixing carboxyl-modified polyvinyl alcohol, water and additives uniformly, and the raw materials in mass percentage are composed as follows:

Carboxy-modified polyvinyl alcohol 36%-39%, water 60%-63%, additives 1%-1.5%;

Further, the degree of polymerization of the carboxyl-modified polyvinyl alcohol is 2400, the degree of alcoholysis is 99%, the carboxyl/hydroxyl molar ratio is 3/97, and pH=7;

Further, the auxiliary agent is a polyacrylate defoamer;

Further, the uniform mixing method is as follows: put carboxyl-modified polyvinyl alcohol into water, let it stand at room temperature for 30 minutes to make it fully swell, then place it in a constant temperature water tank at 95°C and heat it to dissolve, then add additives and keep stirring , until a uniform transparent solution is formed, keep warm for later use.

Described nano-titanium/graphene oxide dispersion liquid obtains by following method:

(1) Add 0.1-0.2 parts of nano-TiO ₂ and 0.1 parts of surfactant polyethylene glycol octyl phenyl ether into 100 parts of deionized water according to the mass parts, stir at high speed, and then use an ultrasonic machine to ultrasonically disperse for 20-30min, Then add 1-1.5 parts of graphene oxide powder and ultrasonically disperse for 30 minutes to obtain a nano-titanium/graphene oxide aqueous solution;

(2) Add 0.1 part of water reducer to 50 parts of deionized water, stir evenly, then add the nano-titanium/graphene oxide aqueous solution prepared in step (1), stir, and then ultrasonically disperse for 10 minutes to obtain nano-titanium/graphene oxide Dispersions;

Further, the graphene oxide is powdery, with a purity of ≥98%, a diameter of 10 μm-20 μm, a large number of oxygen-containing groups on its surface, and a high degree of dispersion in water;

Further, the nano-TiO ₂ has a purity of about 99%, a particle size of 10nm-50nm, and is hydrophilic;

Further, the water reducer is a polycarboxylate high-performance water reducer with a solid content of 20% and a pH value of 7.

The invention also discloses a preparation method of high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete, which includes the following steps:

1) Add 17.5-18.5 parts by mass of water-reducing agent and 36-39 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; Add 12-13 parts of shrinkage reducing agent and 2.6-3 parts of antifoaming agent weighed into one-third of the total water, and record it as mixed solution 2; prepare 21-22 parts of carboxy-modified polyvinyl alcohol polymer Standby after completion; the total water volume is 85-90 parts;

2) Mix 6.7-7 parts of ramie fiber, 880-890 parts of gravel, 735-740 parts of sand, 535-540 parts of cement, 70-75 parts of fly ash, 90-100 parts of straw ash, and 100-105 parts of silica fume , 4.8-5 parts of nano-silicon, 12.5-12.7 parts of basalt fiber, and 19.2-19.5 parts of CaCO ₃ whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, and CaCO ₃ whiskers on the plate In the disc mixer, put a part of crushed stone, sand, cement, fly ash, straw ash, silica fume, and nano-silicon in the disc mixer in order, and stir for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 21-22 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15-15.5 parts of activator to the disc mixer and stir evenly for 2-3 minutes;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The concrete molding and curing method obtained by the preparation method:

Standard curing: Pour the concrete mixture into cast iron molds to form and vibrate, and let it stand for 1d-2d in a standard curing room with a temperature of 20±2°C and a relative humidity of ≥95%, remove the formwork, and then place it in a standard curing room Maintain until desired age.

In order to overcome the problems of ordinary concrete such as high brittleness, low toughness, poor durability, and poor bonding performance with section steel, the present invention utilizes materials readily available in the market, adopts an improved concrete layered mixing process, and considers the various gelling properties required for specific concrete strength grades. Material dosage ratio and the number and size distribution of cracks in the cement matrix under the corresponding ratio, based on multi-scale crack classification control and continuous particle gradation design of cementitious materials, by adding three different types of ramie fiber, basalt fiber, and CaCO ₃ whiskers Fibers of different sizes and active mineral admixtures of different particle size ranges such as fly ash, straw ash, silica fume, and nano-silicon, and carboxyl-modified polyvinyl alcohol polymers that can fill pores and connect the three fibers, play a template role A high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete was prepared by using the nano-silicon/graphene oxide dispersion liquid, and chemical admixtures such as water reducers and activators. Among them, the ramie fiber with water storage function and toughening effect is used, which can play an "internal maintenance" role in the concrete hydration process and can promote the hydration process of the cementitious material. At the same time, the basalt fiber and CaCO ₃ crystals are used together beard, and use carboxy-modified polyvinyl alcohol polymer to fill the pores, and bond the three fibers to each other to form an organic whole, bridge the cracks of different scales in the concrete, effectively inhibit the development of cracks, and enhance the toughness of the concrete; At the same time, the carboxyl-modified polyvinyl alcohol polymer can also wrap the hydration product, so that the hydration product reacts more fully, and the carboxyl group contained in it forms an ionic bond with Ca ²⁺ , and the hydroxyl group contained in it is in contact with the silicon oxide hydration product. The oxygen forms hydrogen bonds and cross-links with hydration products to effectively fill the pores and make the structure more compact. In addition, mineral admixtures of different particle sizes are added to concrete, including fly ash, straw ash, silica fume and nano-scale nano-silica. On the one hand, a continuous particle gradation is formed between the cementitious materials, The micro-aggregate filling effect can be more effectively exerted. On the other hand, each mineral admixture can exert a pozzolanic effect and a superposition effect. Further, by adding nano-titanium/graphene oxide dispersion liquid, its template effect and composition can be exerted. The nuclear effect can improve the structure of concrete hydration products, thereby reducing the size of pores, reducing the number of harmful pores, and improving the compactness of concrete, so that under the joint action of the two aspects, the bonding interface between concrete and steel is more compact and the bonding With the improvement of the form of hydration products, the strength is further improved, and the grip between the concrete matrix and the fiber material is enhanced, so that the fibers can work together to further improve the toughness of the concrete, and can effectively reduce Cl ^- , SO ₄ ^2- , CO ₂ and other harmful ion intrusion, improve the durability of concrete. The present invention improves the pore structure of the concrete through the synergy between the components, makes the internal structure of the concrete more compact, and specifically suppresses its own hydration shrinkage and cracks of different scales under stress. Finally, a new fiber concrete material with high toughness, high bonding performance, high strength and high durability is prepared.

Compared with prior art, the beneficial effect of the present invention is:

1) the ramie fiber used in the present invention is the long fiber of 40-50mm, has the characteristics of high tensile strength, high elastic modulus and high toughness, can effectively suppress the formation and the development of concrete macro-cracks under complex stress state; ramie fiber The natural hydrophilicity makes the surface have a strong gripping force, and has good bonding ability with the cement matrix, coupled with the sufficient anchoring length of the long fiber, it can effectively prevent the fiber from pulling out and prevent the crack when the concrete cracks The further development of the fiber, and the bridging effect of the fiber can increase the deformation capacity and energy dissipation capacity of the concrete; in addition, the ramie fiber has a unique fiber cavity structure and a huge specific surface area, and its cavity structure can store part of the water, which plays the role of " Internal curing effect" to promote the hydration process of concrete. Therefore, ramie fibers can improve the mechanical properties of concrete and the durability properties such as crack resistance, impermeability and freeze-thaw resistance.

2) The basalt fibers and _CaCO whiskers used in the present invention have the characteristics of high strength and high elastic modulus, and the lengths are respectively 12mm and 20μm-30μm, which can effectively inhibit the formation of cracks caused by factors such as concrete plastic shrinkage, dry shrinkage, and temperature changes And development, work together with ramie fiber, play a bridging role, and control the development of cracks in different scales in concrete, which can effectively improve the strength, toughness, deformation performance and durability of concrete; adding carboxyl modified polyvinyl alcohol polymer , a large amount of surface active substances in this kind of polymer can increase the wetting effect of the aggregate surface and improve the bonding ability between the aggregate and the matrix. The particles form a three-dimensional continuous network structure in space, thereby reducing the micro-cracks between the matrix. The network structure of the polymer and the three fibers are connected to each other to form a denser three-dimensional network structure in space, which improves the toughness of concrete and its relationship with concrete. Furthermore, the polymer and the cementitious material have a certain degree of chemical reaction, which strengthens the cross-linking between itself and the hydration product, and also enhances the matrix’s grip on the fiber, preventing the fiber from pulling out when the concrete cracks. out to further prevent cracks from developing. In addition, when the present invention is used in the steel-concrete composite structure, the three kinds of fibers and polymers are evenly dispersed in the concrete and connected with each other to form a three-dimensional network structure, which can effectively restrain the cracks in the surrounding concrete when the steel is stressed, and form a " Circumferential restraint effect" effectively improves the friction force and mechanical bite force between steel and concrete, and then enhances the bonding force between concrete and steel, so that concrete and steel can work better together.

3) The present invention prepares the nano-titanium/graphene oxide dispersion that can be stably dispersed in cement by adding a dispersant. On the one hand, nano-TiO ₂ and graphene oxide play a filling role. On the other hand, nano-TiO 2 has a large surface energy, so that hydration products, especially Ca(OH) _2, can quickly gather on its surface and react, thereby promoting CSH gel. Growth with it as the core limits the formation of harmful crystals and strengthens the interface structure of the cement matrix. Graphene is the thinnest known two-dimensional material with a large specific surface area. It also has the effect of adsorption and plays the role of template, making the hydration products into thick cluster crystals, which further improves the mechanical and durability properties of concrete. On the other hand, the oxygen-containing functional groups on the surface of graphene oxide can be hydrogenated with cement hydration products. Calcium, ettringite, calcium silicate hydrate, etc. react further, change the shape of cement hydration crystal products, enhance the toughness of cement matrix, make the concrete structure have higher flexural and compressive strength, etc., and strengthen concrete and steel bonding properties between them.

4) The present invention considers that potassium ions in straw crops are mainly enriched in young leaves and spores, and the content in mature stems is relatively low, and different types of straw crops have different potassium ion contents, so corn stalks with less potassium ion content are selected. The mature stems are burned at a certain temperature, and then the potassium and sodium are removed by a simple and low-cost potassium removal method, which can effectively prevent the alkali-aggregate reaction in the concrete. The straw obtained by grinding after the potassium removal treatment The ash contains more than 84.1% of silicon dioxide and a certain amount of active Al and Fe oxides. It has high pozzolanic activity. The particles of straw ash are fine (average particle size is 6-12 μm), and the pores inside the straw ash particles And the network channel structure makes it have a large specific surface area, which can reach 12m ² /g. Adding straw ash can make the cementitious material particles more uniform and well-graded, which can play a filling and compacting effect, thereby increasing the cohesion of concrete; in addition, because straw ash has similar pozzolanic activity to silica fume, it can replace part of the silica fume. Ash, reacts with Ca(OH) ₂ in the concrete system to form dense and hard calcium sulfoaluminate hydrate and more stable CSH gel, which improves the flexural strength, compressive strength, splitting tensile strength and durability of concrete ;Finally, straw ash is treated as agricultural waste, and it can be used as building materials to replace part of cement after treatment, which can reduce _CO2 emissions due to straw incineration and cement production process, thereby reducing the cost of concrete, realizing the reuse of agricultural waste, and achieving energy saving environmental protection purposes.

5) The fly ash, straw ash, silica fume, nano-silicon dioxide and cement mixed in the present invention have different particle size ranges, forming a relatively continuous particle gradation of the cementitious material, which can better exert the micro-set At the same time, fly ash, straw ash, silica fume and nano-silicon produce a "super-superposition effect", which further promotes the hydration of cementitious materials, converts more hydration products into CSH gel, and improves the strength of concrete. Pore structure and cohesiveness, in addition, because the particle diameter of nano-silica is only nano-scale, it has a large surface energy and has a nucleation effect, so that hydration products, especially Ca(OH) ₂ , can quickly gather on its surface reaction, thereby promoting the growth of CSH gel with it as the core, limiting the generation of harmful crystals, strengthening the interface structure of the cement matrix, and at the same time, it can enter smaller pores and the surface contains a large number of unsaturated bonds, which can be fully dispersed in other The rapid hydration in the gaps between the particles further improves the flexural strength, compressive strength, splitting tensile strength, toughness, bonding performance and durability of concrete.

6) The shrinkage reducing agent used in the present invention can reduce the surface tension of water in the capillary pores of concrete, make the concrete structure compact, and then control the plastic shrinkage of concrete volume shrinkage, drying shrinkage and hardening early stage, etc., and further improve the crack resistance and seepage resistance of concrete. Enhanced the durability of concrete.

7) activator among the present invention adopts organic-inorganic compound activator, is to be to play activating action jointly by dihydrate gypsum, calcium chloride and triethanolamine, impels the generation of ettringite, makes to be mixed with fly ash, silica fume, Concrete made of nano-silica and straw ash has a certain degree of micro-expansion, which improves the shrinkage performance of concrete. Depolymerize the vitreous network structure on the surface of fly ash by compound activator, thereby stimulating the potential activity of fly ash, which can enhance the three-dimensional structure of vitreous body with aluminosilicate as the main hydration component in the hydration process of fly ash. Corrosion, improve the power of positive hydration reaction, generate more crystals such as CSH gel and calcium aluminate hydrate, and promote fly ash to participate in the early hydration process. The excitation effect of dihydrate gypsum on mineral admixture is reflected in: SO ^4- reacts with the gel on the surface of fly ash particles and AlO ^2- dissolved in the liquid phase to form calcium sulfoaluminate hydrate AFT; in addition, SO ₄ ^2- can also replace part of SiO ₂ ^2- in calcium silicate hydrate, and the replaced SiO ₂ ^2- reacts with Ca ²⁺ in the outer layer to form calcium silicate hydrate, which continuously stimulates the activity of fly ash, which provides Ca ²⁺ reacts with SiO ₂ , Fe ₂ O ₃ , and Al ₂ O ₃ in fly ash, silica fume, nano-silica, and straw ash to form calcium silicate hydrate, calcium ferrite hydrate, and aluminum hydrate calcium acid etc. The excitation of calcium chloride to mineral admixtures is mainly achieved by increasing the concentration of Ca ²⁺ in the hydration system, forming chloroaluminate hydrate gel phase and calcium aluminate hydrate. Calcium chloride, as a strong electrolyte, can also supplement the Ca ²⁺ needed for the activation of fly ash by sulfate and the reaction of silica fume, straw ash, and nano-silica. Triethanolamine, as an active stimulator of organic fly ash, can promote the dissolution of the surface of fly ash particles by complexing the Fe and Al phases in fly ash during the hydration process to make the active substances in fly ash Further hydration. The synergy between dihydrate gypsum, calcium chloride and triethanolamine can fully stimulate the activity of mineral admixtures, accelerate the hydration rate of cementitious materials in the system, promote the formation of hydration products, and then improve the strength and durability of concrete performance etc.

8) The layered mixing method is adopted in the present invention, and the maximum crushed stone particle size is determined through tests, which can disperse the long fibers and the aggregate evenly to the greatest extent, avoid mutual interference between the long fibers and the coarse aggregate, and cause fiber agglomeration to occur. As a result, large holes are produced in the cement matrix, and even the phenomenon of "honeycomb pitting" appears.

The above measures can effectively improve the compressive strength, toughness, deformation ability, durability, etc. of concrete, and enhance the bond strength and collaborative deformation ability between concrete and section steel. In the high-toughness and high-cohesion C220 ultra-high-strength hybrid fiber concrete prepared by the method of the present invention, the particle sizes of various cementitious materials with different particle diameters in the concrete are evenly distributed from large to small, and the various cementitious materials are fully utilized. The micro-aggregate filling effect of the material enables the hydration products of the gelled material to be stacked densely, and the template action and nucleation of graphene oxide and nano-TiO ₂ improve the physical and mechanical properties of the hydration products themselves, further improving the The pore structure of the concrete, while the multi-scale fibers are evenly dispersed, organically unified under the bonding action of the carboxyl-modified polyvinyl alcohol polymer, forming a three-dimensional space network structure, which effectively inhibits the development of cracks of different sizes, so the concrete has a high It has excellent toughness and excellent durability, and has good bonding performance with section steel, and the deformation ability has been further improved, and the synergy with section steel has been enhanced. The 28d cubic compressive strength of the fiber concrete is not less than 221.94MPa, the flexural strength is not less than 54.31MPa, the splitting tensile strength is not less than 26.01MPa, the bonding strength with the section steel is not less than 10.99MPa, and the chloride ion migration coefficient is not less than Greater than 8×10 ^-14 m ² /s. The invention prepares high-performance hybrid fiber concrete with high volume stability, high durability and high toughness. The raw materials are easy to obtain and the preparation process is simple, which meets the requirements of sustainable development and the application and promotion of modern green building materials. A green and environmentally friendly new high-performance hybrid fiber-reinforced concrete material.

Detailed ways

In the following, the present invention will be further described in detail by using examples in combination with specific embodiments, so as to make the advantages of the present invention easier to be understood by those skilled in the art, but it is not intended to limit the protection scope of the present invention.

The high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete of the present invention is prepared by the following method:

1) Add 17.5-18.5 parts by mass of water-reducing agent and 36-39 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; Add 12-13 parts of shrinkage reducing agent and 2.6-3 parts of antifoaming agent weighed into one-third of the total water, and record it as mixed solution 2; prepare 21-22 parts of carboxy-modified polyvinyl alcohol polymer Standby after completion; the total water volume is 85-90 parts;

2) Mix 6.7-7 parts of ramie fiber, 880-890 parts of gravel, 735-740 parts of sand, 535-540 parts of cement, 70-75 parts of fly ash, 90-100 parts of straw ash, and 100-105 parts of silica fume , 4.8-5 parts of nano-silicon, 12.5-12.7 parts of basalt fiber, and 19.2-19.5 parts of CaCO ₃ whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, and CaCO ₃ whiskers on the plate In the disc mixer, put a part of crushed stone, sand, cement, fly ash, straw ash, silica fume, and nano-silicon in the disc mixer in order, and stir for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 21-22 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15-15.5 parts of activator to the disc mixer and stir evenly for 2-3 minutes;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The forming and maintenance method of concrete among the present invention are as follows:

The concrete mixture was poured into the cast iron mold, and the vibrating table was used to vibrate, and then the vibrating rod was used to vibrate in contact with the outer wall of the test mold to discharge the excess air bubbles in the concrete mixture; after molding, the test block was placed at a temperature of In an environment of 20±2°C, cover the surface of the test block with a wet geotextile, let it stand for 1d, remove the formwork, and then maintain it in a standard curing room with a temperature of 20±2°C and a relative humidity of ≥95% to the required age. Expect.

in:

The cement is P·I62.5R grade Portland cement, and the cement variety with good compatibility with polycarboxylate water reducing agent is selected.

The fine aggregate is made of hard sand with a mass ratio of 1:1 and high-quality quartz sand with good grading. The sand fineness modulus is 2.8-3.0, the silica content in the quartz sand is not less than 98%, and the particle size is 0.3 -0.6mm, the density is 2.62g/cm ³ ;

The crushed stones are well-graded, compact and hard, and rough-surfaced basalt crushed stones, with a particle size range of 5-10mm, and are graded according to continuous particle size.

The fly ash is high-quality grade I fly ash from power plants, the sieve residue of 45μm square hole is not more than 10%, the water demand ratio is not more than 95%, the specific surface area should be more than 400m ² /kg, and the average particle size is in the range of 10-30μm .

Straw ash is obtained by incinerating the stems of mature corn stalks at a temperature of 650-820°C, then undergoing potassium removal treatment, and then using a ball mill to grind for 25 minutes. Its silicon dioxide content is 84.1%, and the average particle size is 6-12 μm , the specific surface area is greater than 12m ² /g.

Wherein, the potassium-removing treatment method steps are as follows:

1) Put the straw ash in distilled water, stir and soak, then let it stand, pour off the supernatant and continue to add distilled water to stir and soak, repeat this process more than 5 times, and the soaking time lasts for one week;

2) After pouring out the supernatant for the last time, heat it to 90°C with distilled water and keep it warm for 15-20 minutes. After the heat preservation is over, pour out the supernatant, add distilled water to soak, and repeat step 1);

3) Repeat steps 1) and 2) twice in order;

4) Finally, keep warm at 60°C for 2 hours, pour off the supernatant, and dry for later use.

The silicon dioxide content of the silica fume is greater than 95%, the pozzolanic activity index is greater than 95%, the average particle diameter is 0.1 μm-0.15 μm, and the specific surface area is greater than 28m ² /g.

Among them, nano-silicon is high-purity nano-silicon dioxide prepared by gas phase method, the purity is greater than 99%, the average particle size is 10nm-40nm, and the specific surface area is greater than 130m ² /g.

The water reducer is a polycarboxylate high-performance water reducer suitable for cementitious material systems with low water-to-binder ratio and high silica fume content. The solid content is 20%, the water reducing rate is above 38%, and the pressure resistance is 7d and 28d. The strength ratio is not less than 180%, and there is no adverse effect on the compressive strength of concrete.

The shrinkage reducer is SU-SRA type shrinkage reducer. The defoamer uses Liqi X-2756 high-efficiency concrete defoamer.

The activator adopts an organic-inorganic composite activator, and the composite activator is compounded according to the following raw materials in terms of mass percentage:

Dihydrate gypsum 50-58%, calcium chloride 40-48%, triethanolamine 1.5-2%.

Ramie fiber is dry hemp fiber after alkali treatment and drying, the length is 40-50mm, the diameter is 30μm-40μm, the tensile strength is ≥1000MPa, the elastic modulus is ≥11.4GPa, the elongation at break reaches 8.9%, and the specific gravity is 1.54-1.55g /cm ³ , has good hydrophilicity, high grip strength and acid and alkali resistance.

The length of basalt fiber is 12mm, the diameter is 7μm-15μm, the tensile strength is ≥3000MPa, the elastic modulus is ≥91GPa, and the specific gravity is 2.63-2.65g/cm ³ ;

The length of CaCO ₃ whiskers is 20μm-30μm, the diameter is 0.5μm-2μm, the tensile strength is ≥3000MPa, the elastic modulus is ≥410GPa, and the specific gravity is 2.86g/cm ³ .

Carboxyl-modified polyvinyl alcohol polymer is an organic polymer obtained by mixing carboxyl-modified polyvinyl alcohol, water and additives uniformly, and the raw material composition in terms of mass percentage is as follows:

Carboxy-modified polyvinyl alcohol 36%-39%, water 60%-63%, additives 1%-1.5%;

Among them, the degree of polymerization of carboxyl-modified polyvinyl alcohol is 2400, the degree of alcoholysis is 99%, the carboxyl/hydroxyl molar ratio is 3/97, pH=7; the auxiliary agent is polyacrylate defoamer.

The method of mixing evenly is as follows: put carboxyl-modified polyvinyl alcohol into water, let it stand for 30 minutes at room temperature to make it fully swell, then place it in a constant temperature water tank at 95°C and heat it to dissolve, then add additives and keep stirring until a uniform Transparent solution, keep warm for use.

Nano titanium/graphene oxide dispersion liquid obtains by following method:

(1) Add 0.1-0.2 parts of nano-TiO ₂ and 0.1 parts of surfactant polyethylene glycol octyl phenyl ether into 100 parts of deionized water according to the mass parts, stir at high speed, and then use an ultrasonic machine to ultrasonically disperse for 20-30min, Then add 1-1.5 parts of graphene oxide powder and ultrasonically disperse for 30 minutes to obtain a nano-titanium/graphene oxide aqueous solution;

(2) Add 0.1 part of water reducer to 50 parts of deionized water, stir evenly, then add the nano-titanium/graphene oxide aqueous solution prepared in step (1), stir, and then ultrasonically disperse for 10 minutes to obtain nano-titanium/graphene oxide Dispersions;

Among them, graphene oxide is in powder form, with a purity of ≥98%, and a diameter of 10μm-20μm. Its surface has a large number of oxygen-containing groups and has a high degree of dispersion in water; nano-TiO ₂ has a purity of about 99%, and a particle size of 10nm -50nm, hydrophilic.

The water reducer is a polycarboxylate high-performance water reducer with a solid content of 20% and a pH value of 7. Different specific examples are given below to further illustrate the preparation method of the present invention.

Example 1

1) Add 18.5 parts by mass of water-reducing agent and 39 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; 13 parts of shrinkage reducing agent and 2.6 parts of antifoaming agent are added to one-third of the total water, which is recorded as mixed solution 2; 21 parts of carboxy-modified polyvinyl alcohol polymers are prepared for later use; the total water is 85 parts; Among them, the nano-titanium/graphene oxide dispersion is made of 1.6 parts of graphene oxide powder and 0.2 parts of nano- _TiO2 ; the carboxyl-modified polyvinyl alcohol polymer is prepared from the raw materials in mass percentage: carboxyl-modified polyvinyl alcohol 37 %, water 62%, polyacrylate defoamer 1%;

2) Mix 6.9 parts of ramie fiber, 885 parts of gravel, 740 parts of sand, 537 parts of cement, 75 parts of fly ash, 90 parts of straw ash, 105 parts of silica fume, 4.9 parts of nano silicon, 12.5 parts of basalt fiber, 19.2 parts of CaCO ₃ Whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, CaCO ₃ whiskers in the disc mixer, and then a part of gravel, sand, cement, fly ash, straw Ash, silica fume, and nano-silicon are placed in a pan mixer in sequence, and stirred for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 21 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15.5 parts of activator to the disc mixer, and stir evenly for 2-3 minutes; wherein, the activator is compounded according to the raw materials in terms of mass percentage: 54% of dihydrate gypsum, 44% of calcium chloride, triethanolamine 2 %;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The forming and curing method of concrete in the present embodiment are as follows:

The concrete mixture was poured into the cast iron mold, and the vibrating table was used to vibrate, and then the vibrating rod was used to vibrate in contact with the outer wall of the test mold to discharge the excess air bubbles in the concrete mixture; after molding, the test block was placed at a temperature of In an environment of 20±2°C, cover the surface of the test block with a wet geotextile, let it stand for 1d, remove the formwork, and then maintain it in a standard curing room with a temperature of 20±2°C and a relative humidity of ≥95% to the required age. Expect.

Example 2

1) Add 18 parts by mass of water-reducing agent and 38 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; 12.5 parts of shrinkage reducing agent and 3 parts of antifoaming agent are added to the water of one-third of the total water volume, which is recorded as mixed solution 2; 21.5 parts of carboxyl-modified polyvinyl alcohol polymers are prepared for later use; the total water volume is 85 parts; Among them, the nano-titanium/graphene oxide dispersion is made of 1.1 parts of graphene oxide powder and 0.3 parts of nano- _TiO2 ; the carboxyl-modified polyvinyl alcohol polymer is prepared from the raw materials in mass percentage: carboxyl-modified polyvinyl alcohol 39 %, water 60%, polyacrylate defoamer 1%;

2) 7 parts of ramie fiber, 880 parts of gravel, 740 parts of sand, 535 parts of cement, 72.5 parts of fly ash, 95 parts of straw ash, 100 parts of silica fume, 4.9 parts of nano silicon, 12.6 parts of basalt fiber, 19.4 parts of CaCO ₃ Whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, CaCO ₃ whiskers in the disc mixer, and then a part of gravel, sand, cement, fly ash, straw Ash, silica fume, and nano-silicon are placed in a pan mixer in sequence, and stirred for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 21.5 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15 parts of activator to the disc mixer, and stir evenly for 2-3 minutes; wherein, the activator is compounded according to the raw materials in terms of mass percentage: 54.5% of dihydrate gypsum, 43.7% of calcium chloride, 1.8% of triethanolamine %;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The molding and curing method of concrete in this embodiment is the same as that in Embodiment 1.

Example 3

1) Add 18.5 parts by mass of water-reducing agent and 37 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; 12.5 parts of shrinkage reducing agent and 2.6 parts of antifoaming agent are added to the water of one-third of the total water volume, which is recorded as mixed solution 2; 21 parts of carboxyl-modified polyvinyl alcohol polymers are prepared for later use; the total water volume is 85 parts; Among them, the nano-titanium/graphene oxide dispersion is made of 1.6 parts of graphene oxide powder and 0.3 parts of nano- _TiO2 ; the carboxyl-modified polyvinyl alcohol polymer is prepared from the raw materials in mass percentage: carboxyl-modified polyvinyl alcohol 38.7 %, water 60.1%, polyacrylate defoamer 1.2%;

2) Mix 6.8 parts of ramie fiber, 880 parts of gravel, 738 parts of sand, 537 parts of cement, 72 parts of fly ash, 95 parts of straw ash, 103 parts of silica fume, 5 parts of nano silicon, 12.6 parts of basalt fiber, 19.2 parts of CaCO ₃ Whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, CaCO ₃ whiskers in the disc mixer, and then a part of gravel, sand, cement, fly ash, straw Ash, silica fume, and nano-silicon are placed in a pan mixer in sequence, and stirred for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 21 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15.3 parts of activator to the disc mixer, and stir evenly for 2-3 minutes; wherein, the activator is compounded according to the raw materials in terms of mass percentage: 58% of dihydrate gypsum, 40% of calcium chloride, 1.5% of triethanolamine %;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The molding and curing method of concrete in this embodiment is the same as that in Embodiment 1.

Example 4

1) Add 17.5 parts by mass of water-reducing agent and 36 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; 12 parts of shrinkage reducing agent and 2.6 parts of antifoaming agent are added to 1/3 of the total water, which is recorded as mixed solution 2; 22 parts of carboxy-modified polyvinyl alcohol polymers are prepared for later use; the total water is 90 parts; Among them, the nano-titanium/graphene oxide dispersion is made of 1.2 parts of graphene oxide powder and 0.2 parts of nano-TiO ₂ ; the carboxy-modified polyvinyl alcohol polymer is prepared from the raw materials in mass percentage: carboxy-modified polyvinyl alcohol 37.5 %, water 61%, polyacrylate defoamer 1.5%;

2) 6.7 parts of ramie fiber, 885 parts of gravel, 735 parts of sand, 540 parts of cement, 73 parts of fly ash, 90 parts of straw ash, 103 parts of silica fume, 5 parts of nano silicon, 12.6 parts of basalt fiber, 19.5 parts of CaCO ₃ Whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, CaCO ₃ whiskers in the disc mixer, and then a part of gravel, sand, cement, fly ash, straw Ash, silica fume, and nano-silicon are placed in a pan mixer in sequence, and stirred for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 22 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15 parts of activator to the disc mixer, and stir evenly for 2-3 minutes; wherein, the activator is compounded according to the raw materials in terms of mass percentage: 52.2% of dihydrate gypsum, 46% of calcium chloride, and 1.8% of triethanolamine. %;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The molding and curing method of concrete in this embodiment is the same as that in Embodiment 1.

Example 5

1) Add 17.5 parts by mass of water-reducing agent and 36 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; 12.5 parts of shrinkage reducing agent and 2.6 parts of antifoaming agent are added to the water of one-third of the total water volume, which is recorded as mixed solution 2; 21.5 parts of carboxyl-modified polyvinyl alcohol polymers are prepared for later use; the total water volume is 90 parts; Among them, the nano-titanium/graphene oxide dispersion is made of 1.3 parts of graphene oxide powder and 0.2 parts of nano- _TiO2 ; the carboxyl-modified polyvinyl alcohol polymer is prepared from the raw materials in mass percentage: carboxyl-modified polyvinyl alcohol 37.5 %, water 61.5%, polyacrylate defoamer 1%;

2) Mix 6.8 parts of ramie fiber, 890 parts of gravel, 738 parts of sand, 535 parts of cement, 75 parts of fly ash, 100 parts of straw ash, 100 parts of silica fume, 4.8 parts of nano silicon, 12.6 parts of basalt fiber, 19.2 parts of CaCO ₃ Whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, CaCO ₃ whiskers in the disc mixer, and then a part of gravel, sand, cement, fly ash, straw Ash, silica fume, and nano-silicon are placed in a pan mixer in sequence, and stirred for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 21.5 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15 parts of activator to the disc mixer, and stir evenly for 2-3 minutes; wherein, the activator is compounded according to the raw materials in terms of mass percentage: 50% of dihydrate gypsum, 48% of calcium chloride, triethanolamine 2 %;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The molding and curing method of concrete in this embodiment is the same as that in Embodiment 1.

Example 6

1) Add 18 parts by mass of water-reducing agent and 36 parts by mass of nano-titanium/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; 13 parts of shrinkage reducing agent and 3 parts of antifoaming agent are added to the water of one-third of the total water volume, which is recorded as mixed solution 2; 22 parts of carboxyl-modified polyvinyl alcohol polymers are prepared for later use; the total water volume is 90 parts; Among them, the nano-titanium/graphene oxide dispersion is made of 1.5 parts of graphene oxide powder and 0.3 parts of nano- _TiO2 ; the carboxyl-modified polyvinyl alcohol polymer is prepared from the raw materials in mass percentage: carboxyl-modified polyvinyl alcohol 36 %, water 63%, polyacrylate defoamer 1%;

2) Mix 7 parts of ramie fiber, 890 parts of gravel, 735 parts of sand, 540 parts of cement, 70 parts of fly ash, 100 parts of straw ash, 105 parts of silica fume, 4.8 parts of nano silicon, 12.7 parts of basalt fiber, 19.5 parts of CaCO ₃ Whiskers, respectively divided into three parts, and then evenly spread a part of ramie fiber, basalt fiber, CaCO ₃ whiskers in the disc mixer, and then a part of gravel, sand, cement, fly ash, straw Ash, silica fume, and nano-silicon are placed in a pan mixer in sequence, and stirred for 1 min;

3) In the same way, add the other two ingredients into the pan mixer and stir evenly;

4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes;

5) Add 22 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes;

6) Add 15.2 parts of activator to the disc mixer, and stir evenly for 2-3 minutes; wherein, the activator is compounded according to the raw materials in terms of mass percentage: 54% of dihydrate gypsum, 44.5% of calcium chloride, 1.5% of triethanolamine %;

7) Finally observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the disc mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained.

The molding and curing method of concrete in this embodiment is the same as that in Embodiment 1.

The comparative example is compared with the embodiment of the present invention as follows to further illustrate the effect of the present invention.

Comparative example: Ultra-high-strength concrete without continuous gradation design of gelled particles, without adding fibers, without adding carboxyl-modified polyvinyl alcohol polymer and nano-titanium/graphene oxide dispersion, and using a single activator.

The ratio is: 540 parts of cement, 735 parts of sand, 885 parts of crushed stone, 90 parts of fly ash, 110 parts of silica fume, 120 parts of water, 16.5 parts of water reducing agent, 14.5 parts of activator, and 2.4 parts of defoaming agent.

The preparation method is:

1) Add 16.5 parts by mass of water reducer to two-thirds of the total water, which is recorded as mixed solution 1; add 2.4 parts of defoamer to one-third of the total water , recorded as mixed solution 2, with a total water content of 120 parts;

2) Put 885 parts of gravel, 735 parts of sand, 540 parts of cement, 90 parts of fly ash, and 110 parts of silica fume in a mixer, and stir for 1 minute;

3) Then add the mixed solution 1 in step 1) to the mixer, and stir evenly for 2-3 minutes;

4) Add 14.5 parts of calcium chloride activator to the mixer, and stir evenly for 2-3 minutes;

5) Finally observe the fluidity of the mixture, continue to add the mixed solution 2 prepared in step 1) to the mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform, and the material is discharged , that is, the prepared concrete mixture is obtained; molding and curing are carried out.

The forming and curing method of the concrete described in the comparative example are as follows:

The concrete mixture was poured into the cast iron mold, and the vibrating table was used to vibrate, and then the vibrating rod was used to vibrate in contact with the outer wall of the test mold to discharge the excess air bubbles in the concrete mixture; after molding, the test block was placed at a temperature of In an environment of 20±2°C, cover the surface of the test block with a wet geotextile, let it stand for 1d, remove the formwork, and then maintain it in a standard curing room with a temperature of 20±2°C and a relative humidity of ≥95% to the required age. Expect.

Table 1 shows the performance test results of the high-toughness and high-cohesion C220 ultra-high-strength hybrid fiber concrete prepared in Examples 1-6 and the comparative concrete.

The performance contrast of table 1 embodiment 1-6 and comparative example

It can be seen from Table 1 that the high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete prepared by the present invention can meet the required compressive and flexural strength when the component is loaded, and ensure the bonding strength for cooperating with steel. Its 28d cube compressive strength is not less than 221.94MPa, its flexural strength is not less than 54.31MPa, its splitting tensile strength is not less than 26.01MPa, its bonding strength with section steel is not less than 10.99MPa, and its chloride ion migration coefficient is not greater than 8× ^10-14 m ² /s. Example 3 is the optimal mix ratio, the particle gradation of the gelling material is optimal, the carboxyl-modified polyvinyl alcohol polymer content is optimal, the fiber content is optimal, and the nano-titanium/graphene oxide dispersion liquid. Under the C220 strength grade, it has enough toughness and cohesiveness to improve the synergy between steel and concrete, and can be used as a modern green building material.

The above is only an embodiment of the present invention, and is a further detailed description of the present invention in conjunction with specific optimized implementations, and cannot therefore limit the protection scope of the present invention. Those skilled in the art can use the content and methods disclosed in the present invention, or Under the premise of not departing from the concept of the present invention, any simple changes or substitutions should be considered within the protection scope of the present invention. The protection scope of the present invention shall be determined by the protection scope defined by the disclosed claims.

Claims (7)

1. A high toughness and high cohesion C220 ultra-high-strength hybrid fiber concrete is characterized in that the concrete comprises the raw materials of the following mass fractions: 537 parts of cement, 740 parts of sand, 885 parts of gravel, 75 parts of fly ash, 90 parts of straw ash, 105 parts of silica fume, 4.9 parts of nano-silica, 85 parts of water, 18.5 parts of water reducing agent, and 15.5 parts of activator , 2.6 parts of defoaming agent, 13 parts of shrinkage reducing agent, 6.9 parts of ramie fiber, 12.5 parts of basalt fiber, 19.2 parts of CaCO ₃ whiskers, 39 parts of nano-titanium dioxide/graphene oxide dispersion, 21 parts of carboxy-modified polyvinyl alcohol polymer ; The ramie fiber is fine-dried hemp fiber after alkali treatment and drying, the length is 40-50mm, the diameter is 30μm-40μm, the tensile strength is ≥ 766MPa, the elastic modulus is ≥ 9.1GPa, the elongation at break reaches 8.9%, and the specific gravity is 1.54- 1.55g/ ^cm3 ; The basalt fiber has a length of 12 mm, a diameter of 7 μm-15 μm, a tensile strength ≥ 3000 MPa, a modulus of elasticity ≥ 91 GPa, and a specific gravity of 2.63-2.65 g/cm ³ ; The CaCO ₃ whiskers have a length of 20 μm-30 μm, a diameter of 0.5 μm-2 μm, a tensile strength ≥ 3000 MPa, an elastic modulus ≥ 410 GPa, and a specific gravity of 2.86 g/cm ³ ; The activator adopts an organic-inorganic composite activator, and the composite activator is compounded according to the following raw materials in mass percentage: Dihydrate gypsum 54%, calcium chloride 44%, triethanolamine 2%; The carboxy-modified polyvinyl alcohol polymer is prepared from the following raw materials by mass percentage: 37% carboxy-modified polyvinyl alcohol, 62% water, 1% polyacrylate defoamer, specifically, 37% by mass Put the carboxy-modified polyvinyl alcohol into 62% water, let it stand at room temperature for 30 minutes to make it fully swell, then place it in a constant temperature water tank at 95°C and heat it to dissolve, then add 1% polyacrylate defoamer, and keep stirring Until a uniform transparent solution is formed, it is a carboxyl-modified polyvinyl alcohol polymer; The degree of polymerization of the carboxy-modified polyvinyl alcohol is 2400, the degree of alcoholysis is 99%, the carboxyl/hydroxyl molar ratio is 3/97, and pH=7; The compressive strength of C220 ultra-high-strength hybrid fiber concrete 28d cubes reaches 226.6MPa, the flexural strength reaches 55.5MPa, the splitting tensile strength reaches 26.66MPa, the bonding strength with the section steel reaches 11.17MPa, and the chloride ion migration coefficient reaches 6× 10 ^{- 14} m ² /s. 2. The high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete according to claim 1, wherein the cement is P·I62.5R grade Portland cement; The crushed stones are basalt crushed stones with good gradation, compactness and hardness, and rough surface, and are fed according to the continuous particle size of 5-10mm. The strength of the parent rock is not less than 300MPa, and the maximum particle size is 10mm; The fly ash is high-quality Class I fly ash from a power plant, and its 45 μm square hole sieve residue is not more than 10%, the water demand ratio is not more than 95%, and the specific surface area is greater than 400m ² /kg; The silicon dioxide content in the silica fume is greater than 95%, the pozzolanic activity index is greater than 95%, the average particle size is 0.1μm-0.15μm, and the specific surface area is greater than 28m ² /g; The nano-silica is high-purity nano-silica obtained by gas phase method, its purity is greater than 99%, the average particle size is 10nm-40nm, and the specific surface area is greater than 130m ² /g; The water reducer is a polycarboxylate high-performance water reducer with a solid content of 20% and a water reducing rate of more than 38%. 3. The high-toughness and high-cohesion C220 ultra-high-strength hybrid fiber concrete according to claim 1, wherein the straw ash is incinerated at a temperature of 650-820°C by the mature stems of corn stalks, and then passed through Potassium removal treatment, followed by ball mill grinding for 25 minutes, the silicon dioxide content is greater than 84.1%, the average particle size is 6-12μm, and the specific surface area is greater than 12m ² /g. 4. The high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete according to claim 3, wherein the potassium-removing treatment method comprises the steps of: 1) Stir and soak the straw ash in distilled water, then let it stand still, pour off the supernatant and continue to add distilled water to stir and soak, repeat this process more than 5 times, and the soaking time lasts for one week; 2) After pouring out the supernatant for the last time, heat it to 90°C with distilled water and keep it warm for 15-20 minutes. After the heat preservation is over, pour out the supernatant, add distilled water to soak, and repeat step 1); 3) Repeat steps 1) and 2) twice in order; 4) Finally, keep warm at 60°C for 2 hours, pour off the supernatant, and dry it for later use. 5. The high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete according to claim 1, is characterized in that, the nano-titanium dioxide/graphene oxide dispersion is obtained by the following method: (1) Add 0.2 parts of nano-titanium dioxide and 0.1 part of surfactant polyethylene glycol octylphenyl ether into 100 parts of deionized water according to the mass parts, stir at high speed, and then use an ultrasonic machine to ultrasonically disperse for 20-30 minutes, and then add 1.6 Parts of graphene oxide powder, ultrasonically dispersed for 30min, to obtain nano-titanium dioxide/graphene oxide aqueous solution; (2) Add 0.1 part of water reducer to 50 parts of deionized water, stir evenly, then add the nano-titanium dioxide/graphene oxide aqueous solution prepared in step (1), stir, and then ultrasonically disperse for 10 minutes to obtain nano-titanium dioxide/graphene oxide Dispersion liquid; the graphene oxide is powdery, with a purity ≥ 98%, and a diameter of 10 μm-20 μm; The purity of the nano-titanium dioxide is 99%, and the particle size is 10nm-50nm; The water reducer is a polycarboxylate high-performance water reducer with a solid content of 20% and a pH value of 7. 6. A preparation method based on the high-toughness and high-bonding C220 ultra-high-strength hybrid fiber concrete described in any one of claims 1-5, characterized in that, comprising the steps: 1) Add 18.5 parts by mass of water-reducing agent and 39 parts by mass of nano-titanium dioxide/graphene oxide dispersion into two-thirds of the total water, which is recorded as mixed solution 1; 13 parts of shrinkage reducing agent and 2.6 parts of antifoaming agent are added to one-third of the total water, which is recorded as mixed solution 2; 21 parts of carboxy-modified polyvinyl alcohol polymers are prepared for later use; the total water is 85 parts; 2) 6.9 parts of ramie fiber, 885 parts of gravel, 740 parts of sand, 537 parts of cement, 75 parts of fly ash, 90 parts of straw ash, 105 parts of silica fume, 4.9 parts of nano-silica, 12.5 parts of basalt fiber, 19.2 One part of CaCO ₃ whiskers was divided into three parts, and then one part of ramie fiber, basalt fiber and CaCO ₃ whiskers were evenly spread in the pan mixer, and one part of crushed stone, sand, cement, fly ash , straw ash, silica fume, and nano-silicon dioxide are placed in a pan mixer in sequence, and stirred for 1 min; 3) In the same way, add the other two ingredients into the pan mixer and stir evenly; 4) Then add the mixed solution 1 in step 1) to the disc mixer, and stir evenly for 2-3 minutes; 5) Add 21 parts of prepared carboxy-modified polyvinyl alcohol polymer and stir for 2 minutes; 6) Add 15.5 parts of activator to the disc mixer and stir evenly for 2-3 minutes; 7) Finally, observe the fluidity of the mixture, and continue to add the mixed solution 2 prepared in step 1) to the pan mixer, and stir evenly for 2-3 minutes. After an interval of 3 minutes, stir for another 2-3 minutes until the mixture is uniform. The material is discharged, that is, the prepared concrete mixture is obtained; and it is shaped and maintained. 7. A molding maintenance method of the high-toughness and high-cohesion C220 ultra-high-strength hybrid fiber concrete prepared based on the preparation method described in claim 6, characterized in that, the standard maintenance method is adopted: The standard curing method is as follows: pouring the concrete mixture into a cast iron mold to form and vibrate, and standing in a standard curing room with a temperature of 20±2°C and a relative humidity of ≥95% for 1-2 days, demoulding, and then Cultivate to the desired age in a standard curing room.