Super high-strength concrete material with compressive strength of 500-800 MPa and preparation method

Abstract

The invention provides a super high-strength concrete material with compressive strength of 500-800 MPa and a preparation method of the super high-strength concrete material. The super high-strength concrete material is prepared from 700-1600 parts of an ultrahigh-strength special cementing material, 200-350 parts of quartz powder, 550-1000 parts of fine aggregate, 50-300 parts of water, 0.7-32 parts of a nano powder material, 8-166 parts of high-strength high-elastic modulus fibers and 3.5-48 parts of a special ultrahigh-surface-activity additive. The concrete mix proportion is designed by adopting a super close packing design theory and a critical water film thickness theory for the first time, and the super high-strength concrete material with the compressive strength of 500-800 MPa is prepared by optimizing concrete raw material components and the mix proportion and adopting a warm-pressing technology. Compared with the prior art, the concrete has super high mechanical property, toughness and impermeability, and can realize the ultimate breakthrough of the strength of the existing concrete.

Description

Technical Field

[0001] The invention relates to the technical field of special concrete preparation and molding, and in particular to a super high-strength concrete material with a compressive strength of 500-800 MPa and a preparation method thereof. Background Art

[0002] As the largest building material used in modern civil engineering, concrete is widely used in construction, roads, bridges, tunnels, dams and other projects due to its excellent mechanical properties, durability, economic performance and easy construction performance. The excellent mechanical properties of concrete are the key to its becoming a structural support material, and it is also a prerequisite for ensuring the long-term safe service of concrete engineering. Therefore, how to improve the strength of concrete has become a long-term concern of many researchers since its invention. Many scholars have continuously optimized the raw materials and mix ratio of concrete in order to greatly improve its mechanical properties. For this reason, representative ultra-high performance concrete materials have emerged. They adopt the close packing theory, design the natural stacking of the particle grading of the powder material, and ensure that the mixture has excellent fluidity and forms a matrix structure with ultra-high strength after complete hydration and hardening. At present, the compressive strength of ultra-high performance concrete prepared by existing conventional methods can reach 120MPa~500MPa, while the preparation and research of concrete with higher strength (≥500MPa) are rarely reported.

[0003] Under the guidance of various forward-looking national major projects, modern concrete needs to adapt to the development of lightweight, high-rise, large-span, heavy-load and other structural forms. At the same time, the service of concrete has also shifted from ordinary environmental conditions such as atmosphere, hydraulics, and marine engineering to extreme environmental conditions such as ultra-low temperature, high temperature, ultra-high pressure, and severe corrosion. However, the performance regulation and research of traditional concrete has reached a bottleneck period, which has greatly limited its key applications and extreme service in some future-oriented super projects.

[0004] Therefore, faced with complex structural load-bearing requirements and extreme environmental challenges, the technical problem that needs to be solved urgently is: how to improve the compressive strength of concrete materials to make them super high-strength concrete materials with a compressive strength of 500 to 800 MPa. Summary of the invention

[0005] The present invention is made to solve the above-mentioned problem, and aims to provide a super high-strength concrete material with a compressive strength of 500-800 MPa and a preparation method thereof.

[0006] The present invention provides a super high-strength concrete material, which has the following characteristics: by weight, it includes: 700-1600 parts of super high-strength special cementitious material, 200-350 parts of quartz powder, 550-1000 parts of fine aggregate, 50-300 parts of water, 0.7-32 parts of nano powder material, 8-166 parts of high-strength and high-elastic modulus fiber, and 3.5-48 parts of special super high-surface activity admixture. Among them, the nano powder material is 0.1-2 wt% of the super high-strength special cementitious material, the volume content of the high-strength and high-elastic modulus fiber is 0.5-5%, the special super high-surface activity admixture is 0.5-3 wt% of the total amount of the super high-strength special cementitious material, and the water-cement ratio is 0.05-0.12. Here, the water-cement ratio refers to the ratio of the mass of water to the super high-strength special cementitious material.

[0007] In the super high-strength concrete material provided by the present invention with a compressive strength of 500-800 MPa, it may also have the following characteristics: among them, the super high-strength special cementitious material is composed of 500-900 parts of cement, 100-400 parts of silica fume, and 100-300 parts of mineral powder. The cement is one or several of P·O 525 cement, P·O 625 cement, and P·O 725 cement. The specific surface area of the cement is 350-550 m 2 / kg, and the particle size is 1-30 μm. The specific surface area of the silica fume is 2×10 4 ~2.5×10 4 m 2 / kg, and the particle size is 0.1-0.5 μm; the specific surface area of the mineral powder is 450-1000 m 2 / kg, and the particle size is 50-100 μm; the specific surface area of the quartz powder is 1.5×10 4 ~2.5×10 4 m 2 / kg, and the particle size is 0.5-10 μm.

[0008] In the super high-strength concrete material provided by the present invention with a compressive strength of 500-800 MPa, it may also have the following characteristics: among them, the nano powder material is one or several of nano-SiO2, nano-CaCO3, and nano-carbon fiber. The specific surface area of the nano powder material is 7×10 5 ~1×10 6 m 2 / kg, and the particle size is 0.001-0.1 μm. The fine aggregate is one or several of granite, basalt, quartz sand, and metal steel aggregate. The particle size of the fine aggregate is 75-1000 μm, and the compressive strength of the aggregate is greater than 200 MPa.

[0009] The super high strength concrete material with a compressive strength of 500-800 MPa provided by the present invention may also have the following characteristics: wherein the high strength and high elastic modulus fiber is one or more of organic fiber, inorganic polymer fiber and metal fiber, the organic fiber includes carbon fiber, aramid fiber and ultra-high molecular weight polyethylene fiber, the inorganic polymer fiber includes glass fiber, and the metal fiber includes steel fiber, the high strength and high elastic modulus fiber has a diameter of 0.05-0.5 mm, a length of 1-10 mm, and a shape of one or more of linear, flat mesh and three-dimensional shapes, a tensile strength of 2850-4000 MPa, and an elastic modulus of 100-300 GPa, the special super high surface active admixture is one or more of a surfactant, an anionic surfactant, a non-ionic surfactant, an amphoteric surfactant and a compound surfactant, and the special super high surface active admixture has a water reduction rate of 30-45%.

[0010] The present invention also provides a method for preparing a super high-strength concrete material with a compressive strength of 500-800 MPa, which has the following characteristics: the preparation method is a normal temperature casting molding method or a high temperature pressing molding method.

[0011] In the preparation method of the super high strength concrete material with a compressive strength of 500 to 800 MPa provided by the present invention, it can also have the following characteristics: wherein, the room temperature casting molding method specifically includes the following steps: S1, designing the mix ratio of the super high strength concrete material based on the ultra-dense packing design theory and the critical water film thickness theory, and preparing concrete raw materials of corresponding specifications according to the raw material design parameters; S2, fully dry-mixing the raw materials in step S1 and adding water, stirring to a fluid state to obtain a concrete mixture; S3, loading the concrete mixture into a mold, covering it with a plastic wrap and letting it stand for 20 to 30 hours before removing the mold to obtain a super high strength concrete material; S4, curing the super high strength concrete material for 3 days, 7 days or 28 days by using one or a combination of standard curing, steam curing or hot water curing.

[0012] In the preparation method of the super high strength concrete material with a compressive strength of 500-800 MPa provided by the present invention, it can also have the following characteristics: wherein, the raw materials of the concrete in step S1 are, by weight, 700-1600 parts of super high strength special cementitious material, 200-350 parts of quartz powder, 550-1000 parts of fine aggregate, 0.7-32 parts of nano powder material, 8-166 parts of high strength and high elastic modulus fiber and 3.5-48 parts of special super high surface active admixture.

[0013] In the method for preparing a super high-strength concrete material with a compressive strength of 500 to 800 MPa provided by the present invention, it may further have the following characteristics: Among them, the high-temperature pressing and forming method specifically includes the following steps: (1) Design the mix ratio of the super high-strength concrete material based on the super close packing design theory and the critical water film thickness theory, and prepare concrete raw materials of corresponding specifications according to the raw material design parameters; (2) Thoroughly dry-mix and mix the raw materials in step (1) and add water, and stir until in a uniformly moist state to obtain a wet powder material; (3) Weigh a certain amount of the wet powder material, fill it into the pressure mold multiple times, and perform ultrasonic dispersion on the mold; (4) Place the pressure mold on a universal material testing machine, set the temperature parameters and mechanical pressure parameters to obtain a filled concrete mold; (5) Perform high-temperature pressing on the filled concrete mold, take out the mold and disassemble it after the test to obtain the super high-strength concrete material; (6) Cure the super high-strength concrete material by one or a combination of standard curing, steam curing, or hot water curing for 3d, 7d, or 28d.

[0014] In the method for preparing a super high-strength concrete material with a compressive strength of 500 to 800 MPa provided by the present invention, it may further have the following characteristics: Among them, the concrete raw materials in step (1) are, by weight, 700 to 1600 parts of a super high-strength special cementitious material, 200 to 350 parts of quartz powder, 550 to 1000 parts of fine aggregate, 0.7 to 32 parts of nano powder material, 8 to 166 parts of high-strength and high-elastic modulus fiber, and 3.5 to 48 parts of a special super high surface activity admixture.

[0015] In the method for preparing a super high-strength concrete material with a compressive strength of 500 to 800 MPa provided by the present invention, it may further have the following characteristics: Among them, the temperature parameters in step (4) include: the target temperature is -20 to 600 °C, the heating and cooling time is 0.5 to 3 h, the constant temperature time is 0.5 to 12 h, and the number of cycles is 0 to 10 times; the mechanical pressure parameters in step (4) include: the target pressure is 100 to 20000 kN, the target strength is 10 to 1000 MPa, the loading / unloading rate is force control of 0.5 to 5 MPa / s or displacement control of 0.5 to 5 mm / min, and the constant pressure time is 0.5 to 12 h.

[0016] Functions and effects of the invention

[0017] A super high-strength concrete material with a compressive strength of 500 - 800 MPa and a preparation method thereof according to the present invention. The present invention first uses the ultra-close packing theory and the critical water film thickness theory to design the mix proportion of concrete. By considering the dry and wet powder packing parameters, the temperature and pressure compaction parameters of cement paste, and the hydration compaction characteristics and parameters of hardened cement paste, the packing structure parameters of cement hydration products are hierarchically designed from the nano-scale, micro-scale, and macro-scale. Finally, the super high-strength concrete is prepared by the normal temperature casting forming method and the high temperature pressing forming method. During the pressing forming process, the wet powder material realizes ultra-close packing between particles under the action of pressure. At this time, the cement paste is completely composed of extruded and compacted particles with wetted surfaces, and there is no porosity inside. With the cement hydration reaction under temperature and pressure, more and more hydration products are formed and continuously extruded and compacted to fill the internal structure space of the concrete, finally generating an ultra-high (≥500 MPa) strength.

[0018] The super high-strength concrete material of the present invention, by weight, comprises: 700 - 1600 parts of super high-strength special cementitious material, 200 - 350 parts of quartz powder, 550 - 1000 parts of fine aggregate, 50 - 300 parts of water, 0.7 - 32 parts of nano powder material, 8 - 166 parts of high-strength and high-elastic modulus fiber, and 3.5 - 48 parts of special super high surface activity admixture. Among them, the nano powder material is 0.1 - 2 wt% of the super high-strength special cementitious material, the volume fraction of the high-strength and high-elastic modulus fiber is 0.5 - 5%, the special super high surface activity admixture is 0.5 - 3 wt% of the total amount of the super high-strength special cementitious material, and the water-cement ratio is 0.05 - 0.12. The present invention adopts this specially designed mix proportion, and finally enables the compressive strength of the concrete material to reach 500 - 800 MPa. Specific embodiments

[0019] In order to make the technical means, creative features, achieved purposes and effects realized by the present invention easy to understand, the following embodiments specifically elaborate on the super high-strength concrete material with a compressive strength of 500 - 800 MPa and the preparation method thereof according to the present invention.

[0020] Example 1

[0021] In this example, the super high-strength concrete material with a compressive strength of 500 - 800 MPa is prepared by the normal temperature casting forming method. The preparation method specifically includes the following steps:

[0022] S1, Weigh the raw materials according to the parts by mass in Table 1, where the cement is P·O 525 cement, the particle size of nano-SiO₂ is 0.01 μm, the fine aggregate is granite with a continuous gradation of particle sizes from 75 to 300 μm: the steel fiber is a straight copper-plated steel fiber with a diameter of 0.1 mm, a length of 3 mm, and a tensile strength of 3900 MPa; the special super-high surface activity admixture is a polycarboxylate-based water reducer with a super-high water reducing rate.

[0023] Table 1 Mix proportion of concrete raw materials in Example 1

[0024]

[0025] S2, Thoroughly dry-mix the materials in step S1 and add 150 parts of water, then stir until it reaches a fluid state to obtain a concrete mixture.

[0026] S3, Pour the concrete mixture into a mold, cover it with plastic wrap and let it stand for 24 h, then remove the mold to obtain a super-high-strength concrete material.

[0027] S4, Cure the super-high-strength concrete material by steam curing for 3 d, 7 d, and 28 d, and after the curing is completed, take it out to test the mechanical properties of the concrete.

[0028] In this example, based on the super-close packing design theory and the critical water film thickness theory, the mix proportion of a super-high-strength concrete material with a compressive strength of 500 - 800 MPa is designed, and the corresponding specifications of concrete raw materials are prepared according to the raw material design parameters. The performance test of the super-high-strength concrete material in this example shows that: the compressive strength of this concrete is 579.9 MPa, the tensile strength is 56.5 MPa, the elastic modulus is 61.3 GPa, the porosity is 0.04%, and the impermeability grade ≥ P12.

[0029] In this example, the raw material ratio of the super-high-strength concrete material is designed according to the super-close packing structure design method, which specifically includes the following steps:

[0030] First, calculate the mixing ratio of the initial material powders in a tightly packed state in the dry state to determine the volume ratio of cement, silica fume, blast furnace slag powder, quartz powder, fine aggregate, and nano-powder.

[0031] According to the particle size distribution of the initial materials, use the modified Anderson model to calculate the mixing ratio of each powder material in a tightly packed state in the dry state. The initial materials are cement, silica fume, blast furnace slag powder, quartz powder, fine aggregate, and nano-powder, where the gel materials are cement, silica fume, and blast furnace slag powder.

[0032] The particle size of P·O 525 cement is 1 - 25 μm, the specific surface area is 378 m 2 / kg, and the density is 3140 kg / m 3; The particle size of silica fume is 0.2 - 0.7 μm, the specific surface area is 25400 m 2 / kg, and the density is 2450 kg / m 3 ; The particle size of mineral powder is 70 - 90 μm, the specific surface area is 790 m 2 / kg, and the density is 337 kg / m 3 ; The particle size of quartz powder is 2 - 8 μm, the specific surface area is 21800 m 2 / kg, and the density is 2730 kg / m 3 ; The nano powder material is nano - SiO₂, the particle size is 0.005 - 0.05 μm, the specific surface area is 850000 - 1100000 m 2 / kg, and the density is 121 kg / m 3 ; The fine aggregate is metallic steel aggregate, the particle size is 100 - 900 μm, the specific surface area is 89 m 2 / kg, and the density is 7790 kg / m 3 ; The steel fiber is ultra - high strength steel fiber with a diameter of 0.08 - 0.4 mm and a length of 2 - 12 mm, and the density is 7860 kg / m 3 ; During the mixing process of the powder components, 2% of a special super - high surface activity admixture is added, and the water - reducing efficiency is 40 - 45%.

[0033] Calculate the blending ratio of each powder material in the dry - state dense packing according to the particle - size distribution of the initial materials by using the modified Anderson model:

[0034]

[0035] In the formula, P(D) is the fraction of solids smaller than particle size D; D max is the maximum particle size in the solid; D min is the minimum particle size; q is the distribution modulus. Adjust the mass ratio of solid particles by using the least - squares method according to the above formula, so that the solid - particle mixture reaches the best - fitting position of the target curve, thereby determining the volume ratio of cement, silica fume, mineral powder, quartz powder, fine aggregate, and nano powder.

[0036] Second, based on the volume ratio of cement, silica fume, mineral powder, quartz powder, fine aggregate, and nano powder, establish the quantitative relationship between the concrete forming pressure and the water - film thickness through the wet - packing density.

[0037] Adopt ultrasonic dispersion to ensure the uniformity during the mixing process with water, and establish the quantitative relationship between the water - film thickness, the forming pressure, and the water - binder ratio:

[0038]

[0039] In the formula, τ is the wet - packing density; M is the weight of the mixture; V is the volume size under the action of pressure; ρ w, c , f , m , q , a , n are the densities of water, cement, silica fume, mineral powder, quartz powder, fine aggregate, and nano powder respectively; Y w , Y c , Y f , Y m , Y q , Y a , Y n are the volume ratios of water, cement, silica fume, mineral powder, quartz powder, fine aggregate, nano powder and the total mixture, respectively.

[0040]

[0041] Where λ is the porosity of the concrete after mixing; A is the specific surface area of the cementitious material component, A c , A f , A m are the specific surface areas of cement, silica fume and mineral powder respectively; R c , R f , R m are the volume ratios of cement, silica fume, mineral powder and cementitious materials respectively, and d is the thickness of water film.

[0042] The relationship between the wet bulk density of the mixture under pressure is described by the Heckel equation:

[0043] τ(P)=ae -kP +b

[0044] The relationship between the ultra-close packing coefficient and the water-binder ratio-pressure is obtained by combining with the obtained fitting formula. The relationship between the water film thickness and the molding pressure-water-binder ratio is obtained by combining with the above obtained fitting formula. The water-binder ratio refers to the ratio of water to gel material.

[0045] d(P,w)=ae -kP +bw+c

[0046] Where P is the molding pressure, w is the water-binder ratio, a, b, and c are the density constants of the powder under pressure, which are calculated by fitting the porosity results of some different water-binder ratios and molding pressures using MATLAB.

[0047] 3. Determine the initial curing conditions of concrete and the thickness of the external hydration product layer of cement particles under the corresponding conditions.

[0048] Establish the thickness of the hydrated product layer outside the cement particles under the initial curing conditions of concrete: The initial curing conditions are a temperature of 30 - 90 °C and a humidity of 40 - 95%. According to the literature, the increase in the thickness of the outer hydrated product mainly occurs from the end of the induction period to the middle of the acceleration period of the exothermic curve. Subsequently, the hydration process mainly involves the change of the internal hydrated product layer. Therefore, when the growth of the outer hydrated product layer stops, it marks the maximum particle size after the hydration of the cement particles. In this invention, the growth of the outer product is completed after 2 days. Establish the functional relationship between it and the outer hydrated product layer by measuring the degree of hydration of cement with different water-binder ratios under standard curing conditions at 2 days:

[0049] DoH' = DoH(w) * T * RH

[0050]

[0051] In the formula, DoH is the degree of hydration of cement particles with different water-binder ratios under standard curing conditions at 2 days, and the functional relationship is fitted by MATLAB. DoH' is the degree of hydration considering temperature and humidity, T is the temperature influence coefficient, t is the temperature, RH is the humidity influence coefficient, and h is the humidity. Establish the functional relationship between it and the outer hydrated product layer by measuring the degree of hydration of cement with different water-binder ratios under standard curing conditions at 2 days:

[0052] V 2d = V unreact + V product

[0053] In the formula, V 2d is the volume of the cement after 2 days of curing, mainly composed of the volume of the hydrated product V product and the volume of the unhydrated product V unreact And it is considered that when 1 cm 3 of cement particles hydrate, about 2.2 cm 3 of hydrated products are produced. Therefore, the relationship between the initial cement particle volume V initial and V unreact , V product can be calculated.

[0054] V unreact = (1 - DoH) * V initial

[0055] V product = 2.2 * DoH * V initial

[0056] V 2d = (1 + 1.2DoH) * V initial

[0057] Furthermore, the radius R of the outer product is calculated through the volume outerRelationship with the initial radius R initial of.

[0058]

[0059] IV. Based on the ultra - dense packing design where the water film thickness matches the thickness of the external hydration product layer, re - determine the volume ratios of cement, silica fume, blast furnace slag powder, quartz powder, fine aggregate, and nano - powder.

[0060] Based on the ultra - dense packing design where the water film thickness matches the thickness of the outer hydration product layer, when the water film thickness d is consistent with the thickness R of the external hydration product layer of cement particles outer it is defined as the critical water film thickness d critical and match this parameter.

[0061] d = d critical = R outer

[0062] Substitute the corrected cement particle size back into the dense packing equation, and use the least - squares method to re - design the mass ratio of solid particles, and then determine the volume ratios of cement, silica fume, blast furnace slag powder, quartz powder, fine aggregate, and nano - powder.

[0063] Example 2

[0064] In this example, the super - high - strength concrete material with a compressive strength of 500 - 800 MPa is prepared by the high - temperature pressing method. The preparation method specifically includes the following steps:

[0065] (1) Weigh the raw materials according to the parts by mass in Table 2. Among them, the cement is P·O625 cement, the nano - powder material is nano - carbon fiber with a particle size of 0.07 μm, the fine aggregate is continuously graded metal steel aggregate with a particle size of 75 - 450 μm; the high - strength and high - elastic - modulus fiber is composed of a mixture of carbon fiber and three - dimensional reticulated steel fiber; the special ultra - high surface - activity admixture is a polycarboxylate - type water - reducing agent with an ultra - high water - reducing rate.

[0066] Table 2 Mix proportion of concrete raw materials in Example 1

[0067]

[0068] (2) Thoroughly dry - mix the materials in step (1) and add 150 parts of water, and stir until it reaches a uniformly wet state to obtain wet powder materials.

[0069] (3) Fill the wet powder materials into the pressure mold multiple times, and perform ultrasonic dispersion on the mold.

[0070] (4) Place the pressure die on the universal material testing machine and set the temperature parameters: the target temperature is 470 °C, the heating and cooling time is 0.5 h, the constant temperature time is 6 h, the number of cycles is 1 time, and the mechanical pressure parameters: the target pressure is 20000 kN, the target strength is 600 MPa, the pressure increase / decrease rate is force control at 3 MPa / s, and the constant pressure time is 5 h to obtain a filled concrete die.

[0071] (5) Perform high-temperature pressing on the filled concrete die. After the test, take out the die and disassemble it to obtain the ultra-high-strength concrete material.

[0072] (6) Cure the prepared concrete material using standard curing for 3 d, 7 d, and 28 d. After the curing, take it out and test the mechanical properties of the concrete.

[0073] In this embodiment, based on the ultra-close packing design theory and the critical water film thickness theory, the mix ratio of the ultra-high-strength concrete material with a compressive strength of 500 - 800 MPa is designed, and the corresponding specifications of concrete raw materials are prepared according to the raw material design parameters. The performance test of the ultra-high-strength concrete material in this embodiment shows that: the compressive strength of this concrete is 752.3 MPa, the tensile strength is 70.1 MPa, the elastic modulus is 50.3 GPa, the porosity is 0.01%, and the impermeability grade is ≥P12.

[0074] Functions and effects of the embodiment

[0075] The prior art usually calculates the most compact packing ratio of powder materials based on the ultra-close packing theory for the mix ratio design of concrete materials, and there are defects of insufficient strength under some extreme environmental conditions. Compared with the prior art, the embodiment of the present invention is not limited to the ultra-close packing design theory, but according to the physical and chemical reactions and multi-scale structural characteristics in the whole process of concrete hardening, proposes to use the ultra-close packing theory and the critical water film thickness theory to achieve the super high-strengthening of concrete. At the same time, by adjusting the temperature parameters and mechanical pressure parameters, the strength of concrete can be continuously and highly enhanced, breaking through the strength limit of existing concrete.

[0076] In the preparation process of the present invention, the ultrasonic dispersion effect is introduced to replace the traditional mechanical vibration effect, which can not only accelerate the rapid adsorption and uniform dispersion of a small amount of water on the surface of the solid-phase powder material, but also enable all the solid-phase powder materials to quickly form a uniform, stable, and dense homogeneous state, and finally make the microstructure of the concrete more homogeneous, dense, and high-strengthened.

[0077] The present invention uses fiber materials of different types and size specifications, which can ensure that the ultra-high-strength concrete has excellent toughness before being pressed to 500 MPa, and solves the possibility of premature explosion failure.

[0078] The super high-strength concrete prepared by the present invention can meet the following technical standards:

[0079] 1) Mechanical properties: The 28-day compressive strength ≥ 500 MPa, the compressive strength ≥ 50 MPa, and the elastic modulus ≥ 50 GPa.

[0080] 2) Porosity ≤ 0.1%.

[0081] 3) Impermeability: The impermeability grade ≥ P12 (the impermeability grade is determined in accordance with the Specification "Concrete Quality Control Standard" (GB50164~2011)).

[0082] Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A super high-strength concrete material with a compressive strength of 500 - 800 MPa, characterized in that, In parts by weight, it includes: 700-1600 parts of ultra-high strength special cementitious materials, 200-350 parts of quartz powder, 550-1000 parts of fine aggregate, 50-300 parts of water, 0.7-32 parts of nano powder materials, 8-166 parts of high-strength and high-elastic modulus fibers, and 3.5-48 parts of special ultra-high surface active admixtures. Among them, the nano powder material is 0.1-2wt% of the ultra-high strength special cementitious material, the volume content of the high-strength and high elastic modulus fiber is 0.5-5%, the special ultra-high surface active admixture is 0.5-3wt% of the total amount of the ultra-high strength special cementitious material, and the water-cement ratio is 0.05-0.

12.

2. The super high strength concrete material with a compressive strength of 500-800 MPa according to claim 1, characterized in that: Among them, The ultra-high strength special cementitious material is composed of 500 - 900 parts of cement, 100 - 400 parts of silica fume, and 100 - 300 parts of blast furnace slag powder. The cement is one or more of P·O 525 cement, P·O 625 cement, and P·O 725 cement. The specific surface area of the cement is 350 - 550 m 2 / kg, and the particle size is 1 - 30 μm. The specific surface area of the silica fume is 2×10 4 ~2.5×10 4 m 2 / kg, and the particle size is 0.1 - 0.5 μm; the specific surface area of the blast furnace slag powder is 450 - 1000 m 2 / kg, and the particle size is 50 - 100 μm; the specific surface area of the quartz powder is 1.5×10 4 ~2.5×10 4 m 2 / kg, and the particle size is 0.5 - 10 μm.

3. The super high strength concrete material with a compressive strength of 500-800 MPa according to claim 1, characterized in that: Among them, The nano powder material is one or several of nano-SiO2, nano-CaCO3 and nano-carbon fiber. The specific surface area of the nano powder material is 7×10 5 ~1×10 6 m 2 / kg, the particle size is 0.001~0.1μm. The fine aggregate is one or several of granite, basalt, quartz sand and metal steel aggregate. The particle size of the fine aggregate is 75~1000μm, and the compressive strength of the aggregate is greater than 200MPa.

4. The super high strength concrete material with a compressive strength of 500-800 MPa according to claim 1, characterized in that: Among them, The high-strength and high-elastic modulus fiber is one or more of organic fiber, inorganic polymer fiber and metal fiber, the organic fiber includes carbon fiber, aramid fiber and ultra-high molecular weight polyethylene fiber, the inorganic polymer fiber includes glass fiber, and the metal fiber includes steel fiber. The high-strength and high-elastic modulus fiber has a diameter of 0.05-0.5 mm, a length of 1-10 mm, and a shape of one or more of linear, flat mesh and three-dimensional shapes. The tensile strength is 2850-4000 MPa, and the elastic modulus is 100-300 GPa. The special ultra-high surface active admixture is one or more of a surfactant, an anionic surfactant, a non-ionic surfactant, a zwitterionic surfactant and a compound surfactant, and the special ultra-high surface active admixture has a water reduction rate of 30-45%.

5. A method for preparing a super high strength concrete material with a compressive strength of 500 to 800 MPa according to any one of claims 1 to 4, characterized in that: The preparation method is a normal temperature casting molding method or a high temperature pressing molding method.

6. The preparation method of the super high-strength concrete material with a compressive strength of 500 to 800 MPa according to claim 5, characterized in that, The room temperature casting method specifically comprises the following steps: S1, design the mix ratio of super high-strength concrete materials based on the ultra-dense packing design theory and the critical water film thickness theory, and prepare concrete raw materials of corresponding specifications according to the raw material design parameters; S2, fully dry-mixing the raw materials in step S1, adding water, and stirring until fluidity is achieved to obtain a concrete mixture; S3, placing the concrete mixture into a mold, covering it with a plastic wrap and leaving it to stand for 20 to 30 hours before removing the mold to obtain a super high-strength concrete material; S4, curing the super high strength concrete material for 3 days, 7 days or 28 days by using one or a combination of standard curing, steam curing or hot water curing.

7. The method for preparing a super high strength concrete material with a compressive strength of 500-800 MPa according to claim 6, characterized in that: Among them, The concrete raw materials in the step S1 are, by weight, 700 to 1600 parts of ultra-high-strength special cementitious materials, 200 to 350 parts of quartz powder, 550 to 1000 parts of fine aggregate, 0.7 to 32 parts of nano powder materials, 8 to 166 parts of high-strength and high-elastic modulus fibers, and 3.5 to 48 parts of special ultra-high surface activity admixtures.

8. The preparation method of the super high-strength concrete material with a compressive strength of 500 to 800 MPa according to claim 5, characterized in that, The high-temperature pressing forming method specifically includes the following steps: (1) Design the mix proportion of the super-high-strength concrete material based on the super-close packing design theory and the critical water film thickness theory, and prepare the concrete raw materials of corresponding specifications according to the raw material design parameters; (2) Thoroughly dry-mix and mix the concrete raw materials in step (1) and add water, and stir until in a uniformly wet state to obtain wet powder materials; (3) Weigh a certain amount of the wet powder materials, fill them into the pressure mold multiple times, and perform ultrasonic dispersion on the mold; (4) Place the pressure mold on a universal material testing machine, set the temperature parameters and mechanical pressing parameters to obtain a filled concrete mold; (5) Perform high-temperature pressing on the filled concrete mold, take out the mold after the test is completed and disassemble it to obtain the super-high-strength concrete material; (6) Cure the super-high-strength concrete material by one or a combination of standard curing, steam curing or hot water curing for 3d, 7d or 28d.

9. The preparation method of the super-high-strength concrete material with a compressive strength of 500 to 800 MPa according to claim 8, characterized in that: Among them, The concrete raw materials in the step (1) are, by weight, 700 to 1600 parts of ultra-high-strength special cementitious materials, 200 to 350 parts of quartz powder, 550 to 1000 parts of fine aggregate, 0.7 to 32 parts of nano powder materials, 8 to 166 parts of high-strength and high-elastic modulus fibers, and 3.5 to 48 parts of special ultra-high surface activity admixtures.

10. The preparation method of the super-high-strength concrete material with a compressive strength of 500 to 800 MPa according to claim 8, characterized in that: Among them, The temperature parameters in the step (4) include: the target temperature is 20 to 600 °C, the heating and cooling time is 0.5 to 3 h, the constant temperature time is 0.5 to 12 h, and the number of cycles is 0 to 10 times; the mechanical pressing parameters in the step (4) include: the target pressure is 100 to 20000 kN, the target strength is 10 to 1000 MPa, the loading / unloading rate is force control of 0.5 to 5 MPa / s or displacement control of 0.5 to 5 mm / min, and the constant pressure time is 0.5 to 12 h.

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