CN114380558A

CN114380558A - Green high-performance cement concrete and preparation method thereof

Info

Publication number: CN114380558A
Application number: CN202210118692.4A
Authority: CN
Inventors: 李静
Original assignee: Guizhou Daxingwang New Material Technology Co ltd
Current assignee: Guizhou Yatai Yuantong Electric Co ltd
Priority date: 2022-02-08
Filing date: 2022-02-08
Publication date: 2022-04-22
Anticipated expiration: 2042-02-08
Also published as: CN114380558B

Abstract

The invention discloses green high-performance cement concrete and a preparation method thereof. According to the invention, the modified fumed silica is used as the raw material of the concrete, so that the internal pore structure of the concrete is improved, and the salt resistance and the freezing resistance of the concrete are improved; the introduction of the modified gas phase method silicon dioxide is beneficial to the combination of the matrix and the basalt fiber, and the mechanical property of the concrete is improved macroscopically.

Description

Green high-performance cement concrete and preparation method thereof

Technical Field

The invention relates to the technical field of concrete, in particular to green high-performance cement concrete and a preparation method thereof.

Background

The green high-performance cement concrete is a new building material, and compared with the traditional cement concrete, the green high-performance cement concrete has the characteristics of small using amount, high construction performance, high strength and good durability. The consumption of the cement concrete can be reduced on the premise of meeting different use requirements, and the effects of energy conservation and emission reduction are achieved. By changing the components in the cement concrete, the green high-performance cement concrete can improve the compatibility under different environments, and further expand the application field of the concrete.

The patent CN 107721317A discloses a basalt and polyvinyl alcohol mixed fiber concrete and a preparation method thereof, wherein basalt fibers accounting for 0.05 percent of the integral number of a concrete matrix and PVA fibers accounting for 0.05 percent of the integral number of the concrete matrix are mixed in the concrete matrix to improve the toughness and the crack resistance of the concrete, thereby improving the mechanical property and the service life of the concrete. Patent CN 110054443A discloses a high-strength low-shrinkage green concrete and a preparation method thereof, iron tailings are used as fine aggregates to replace part of natural sand to produce the concrete, and the dosage of coarse aggregates and fine aggregates is controlled, so that the effect of improving the strength of the concrete is achieved. The anti-sulfate and anti-freezing performance of the concrete is not improved, the use requirements under different natural environments are difficult to meet, and the application of the concrete is limited.

Disclosure of Invention

In view of the above-mentioned defects of the prior art, the technical problems solved by the present invention are: (1) the sulfate freezing resistance of the concrete is improved; (2) the mechanical strength of the concrete is improved; (3) the layering phenomenon among different components in the concrete is solved.

Salt frost damage is one of the important factors affecting the durability and service life of concrete, and the effect of salt frost on concrete is particularly obvious in cold regions. Due to the loss of sulfate resistance, salt frost damage appears on the surface of the concrete, and gradually diffuses inwards to erode the concrete, so that the performance of the concrete is reduced in all aspects. Silica fume substances are often added in the traditional process to improve the salt resistance of concrete, and the gas phase method silicon dioxide can be used as an additive for improving the salt resistance due to the characteristics of high silicon dioxide content, high specific surface area and the like.

The inventors have found that when fumed silica is added in the prior art, the dispersibility of fumed silica is poor. The surface of the silicon dioxide prepared by the vapor phase method is rich in hydroxyl, so that aggregates are easily formed among particles, and the storage condition is severer; meanwhile, after the fumed silica is added into concrete, a three-dimensional net structure is easily formed in a solid-liquid system due to hydrogen bond combination, so that the local viscosity is increased, and the agglomeration phenomenon is caused. In summary, the use of fumed silica in concrete has high requirements for storage and processing techniques, and is difficult to meet the production and construction requirements in various environments.

Therefore, the inventors modified conventional fumed silica to introduce benzene ring structure and long and short chains into the surface of fumed silica by using hydroxyl groups on the surface of fumed silica, and synergistically exerted the effects. The steric hindrance provided by the benzene ring structure and the long and short chains is large, so that the aggregation among silica particles by a gas phase method can be prevented; after the functional group is introduced, the silica particles in the gas phase method are not easy to adsorb each other under the action of electrostatic repulsion, and the aim of improving the dispersibility is fulfilled. Due to the improvement of the dispersion performance, the fumed silica can carry a large amount of concrete hydration products to be attached to the surface of the basalt fiber, calcium ions and hydroxyl ions in the concrete are adsorbed on the surface of the basalt fiber, the number of crystal nuclei for generating hydrated calcium silicate gel in the hydration process is increased, the combination of the fiber and a cement matrix is firmer, and the mechanical property of the concrete is improved macroscopically.

In order to achieve the purpose, the invention adopts the following technical scheme:

the green high-performance cement concrete is composed of cement, medium sand, broken stone, basalt fiber, modified fumed silica, a water reducing agent and water, and the green high-performance cement concrete comprises the following raw materials in parts by weight: 480-540 parts of cement, 480-540 parts of medium sand, 1050-1200 parts of broken stone, 1.2-8 parts of basalt fiber, 15-36 parts of modified fumed silica, 6.5-13 parts of a water reducing agent and 190-220 parts of water.

Preferably, the cement is any one of PII 42.5 portland cement, PII 42.5R portland cement, PIO 42.5 ordinary portland cement, and PIO 42.5R ordinary portland cement.

Preferably, the crushed stone is continuous graded crushed stone and is prepared from 5-10 mm crushed stone, 10-20 mm crushed stone and 20-31.5 mm crushed stone in a mass ratio of 1: 2: 1 is obtained by blending.

Preferably, the length of the basalt fiber is 1-3 mm.

Preferably, the water reducing agent is any one of a naphthalene-based high-efficiency water reducing agent, an aliphatic high-efficiency water reducing agent, an amino high-efficiency water reducing agent and a polycarboxylic acid high-performance water reducing agent.

Preferably, the modified fumed silica is any one of highly dispersed fumed silica and delamination-preventing fumed silica.

Preferably, the preparation method of the high-dispersion gas-phase method silicon dioxide comprises the following steps:

x1 acidifying the fumed silica with inorganic acid to obtain acidified fumed silica for later use;

x2 dispersing acidified fumed silica in a mixture formed by ethanol and diethyl ether, then adding tetramethyl m-xylylene diisocyanate, n-heptyl isocyanate and 2-naphthyl isocyanate, and reacting at 80-90 ℃ for 12-36 h under an oxygen-free condition to obtain a reaction liquid I for later use;

maintaining the X3 in an anaerobic condition, reducing the temperature of the reaction liquid I to 55-70 ℃, adding propylene glycol butyl ether, and continuing to react for 1-4 hours to obtain a reaction liquid II for later use;

and (3) keeping the X4 in an anaerobic condition, adding 2, 2-bis (hydroxymethyl) malonic acid into the reaction liquid II, continuously reacting for 1-4 h, separating to obtain a solid product, washing with alcohol, drying, and crushing to obtain the high-dispersion gas-phase-method silicon dioxide.

Preferably, the acidification treatment in the step X1 is as follows according to parts by weight: 5-8 parts of fumed silica are taken and placed in 75-125 parts of hydrochloric acid with the concentration of 0.1-0.5 mol/L for soaking for 1-3 h.

Preferably, the usage amount of the mixture of ethanol and diethyl ether in the step X2 is 150-300 parts by weight, wherein the mass ratio of ethanol to diethyl ether is 4: 1.

preferably, the amount of the tetramethyl m-xylylene diisocyanate used in the step X2 is 8 to 24 parts by weight; the using amount of the n-heptyl isocyanate is 1.5-5 parts; the using amount of the 2-naphthyl isocyanate is 0.3-1.2 parts.

Preferably, the propylene glycol butyl ether is used in the step X3 in an amount of 24-56 parts by weight.

Preferably, the 2, 2-bis (hydroxymethyl) malonic acid is used in an amount of 0.4 to 2 parts by weight in step X4.

In long-term practice and use processes, the inventor finds that after the highly-dispersed fumed silica is added into the concrete, the sulfate resistance of the concrete is improved; the high-dispersion gas phase method silicon dioxide improves the microporous structure of concrete, and further reduces the diffusion speed of corrosive ions. However, in the using process, the microstructure of part of the concrete is layered, and as the using time is prolonged, the fine layering can cause structural defects, so that various properties of the concrete are reduced. In view of this phenomenon, the inventors have observed and studied that the cause of the occurrence of the delamination phenomenon is the crystal structure of the highly dispersed fumed silica itself. The invention further improves the high-dispersion gas phase method silicon dioxide, introduces silanol groups into the original functional groups, the silanol groups can form one corner of a tetrahedral crystal structure, thereby improving the original two-dimensional crystal structure, and the silanol groups also have the characteristic of easily forming hydrogen bonds, and can form the hydrogen bonds of adjacent particles, thereby further improving the salt resistance of the concrete.

Preferably, the preparation method of the delamination-proof gas phase method silicon dioxide comprises the following steps:

y1, acidifying the gas-phase method silicon dioxide by using inorganic acid to obtain acidified gas-phase method silicon dioxide for later use;

y2, dispersing acidified fumed silica in a mixture formed by ethanol and ether, then adding tetramethyl m-xylylene diisocyanate, n-heptyl isocyanate and 2-naphthyl isocyanate, and reacting at 80-90 ℃ for 12-36 h under an oxygen-free condition to obtain a reaction liquid I for later use;

y3 is kept under an anaerobic condition, the temperature of the reaction liquid I is reduced to 55-70 ℃, propylene glycol butyl ether is added, and the reaction is continued for 1-4 hours to obtain a reaction liquid II for later use;

y4 is kept under an anaerobic condition, 2-bis (hydroxymethyl) malonic acid is added into the reaction liquid II, the reaction is continued for 1 to 4 hours, then a solid product is obtained by separation, and the high-dispersion gas phase method silicon dioxide is obtained by alcohol washing, drying and crushing for later use;

y5, dispersing the high-dispersion gas-phase method silicon dioxide in N, N-dimethylformamide, then adding mercaptopropyl methyldimethoxysilane, reacting at 75-90 ℃ for 6-12 h, removing the solvent, continuing to react for 1-4 h, separating to obtain a solid product, and then washing with alcohol, washing with water, drying and crushing to obtain a solid product I for later use;

and Y6, dispersing the solid product I in ethanol, adding methacrylamide and benzoin dimethyl ether, and reacting at 80-120 ℃ for 1-3 h to obtain the delamination-proof gas phase method silicon dioxide.

Preferably, the acidification treatment in the step Y1 is as follows according to parts by weight: 5-8 parts of fumed silica are taken and placed in 75-125 parts of hydrochloric acid with the concentration of 0.1-0.5 mol/L for soaking for 1-3 h.

Preferably, the usage amount of the mixture of ethanol and diethyl ether in the step Y2 is 150-300 parts by weight, wherein the mass ratio of ethanol to diethyl ether is 4: 1.

preferably, the usage amount of the tetramethyl m-xylylene diisocyanate in the step Y2 is 8-24 parts by weight; the using amount of the n-heptyl isocyanate is 1.5-5 parts; the using amount of the 2-naphthyl isocyanate is 0.3-1.2 parts.

Preferably, the propylene glycol butyl ether is used in the step Y3 in an amount of 24-56 parts by weight.

Preferably, the 2, 2-bis (hydroxymethyl) malonic acid is used in an amount of 0.4 to 2 parts by weight in step Y4.

Preferably, the amount of the N, N-dimethylformamide used in the step Y5 is 100 to 150 parts by weight; the using amount of the mercaptopropyl methyldimethoxysilane in the step Y5 is 5-8 parts.

Preferably, the usage amount of the ethanol in the step Y6 is 30-90 parts by weight; the usage amount of the methacrylamide is 0.3-0.6 part; the usage amount of benzoin dimethyl ether is 0.1-0.2 parts.

The invention also discloses a preparation method of the green high-performance cement concrete, which comprises the following steps:

s1, weighing the raw materials according to the formula, sequentially adding the cement, the medium sand and the broken stone into water, and stirring to obtain concrete coarse materials for later use;

s2, continuously and sequentially adding basalt fibers, modified fumed silica and a water reducing agent into the concrete coarse material obtained in the step S1, and stirring to obtain concrete mortar for later use;

and S3, carrying out construction pouring, curing and curing on the concrete mortar obtained in the step S2 to obtain the green high-performance cement concrete.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The introduction and the function of part of raw materials in the formula of the invention are as follows:

basalt fiber: the continuous fiber drawn from natural basalt has high breaking strength. The invention is used as the filler of concrete to strengthen the strength of concrete and reduce the shrinkage.

Modified fumed silica: the product is obtained by modifying nanometer white powder generated by hydrolyzing silicon halide in oxyhydrogen flame at high temperature. The invention is used for improving the salt resistance of the concrete.

Tetramethyl m-xylylene diisocyanate: a low-toxicity diisocyanate with unique structure integrates the advantages of aliphatic isocyanate and aromatic isocyanate, and the elastomer prepared from the diisocyanate is soft, has high strength, adhesion and flexibility, and has the advantages of yellowing resistance, acid resistance, durability and the like. The modified silica is used as a modified raw material of fumed silica in the invention.

N-heptyl isocyanate: organic compound, clear yellow liquid. The modified short chain raw material is introduced into the gas phase method silicon dioxide.

2-naphthyl isocyanate: organic compound, white flaky crystal. The modified silicon dioxide is used as a modified raw material for introducing a benzene ring structure into the gas-phase-method silicon dioxide.

Mercaptopropyl methyldimethoxysilane: an organic compound, a silane coupling agent. The present invention is useful for introducing silanol groups into fumed silica.

The invention has the beneficial effects that:

compared with the prior art, the modified fumed silica is used, and the benzene ring structure and the long and short chains are introduced to the surface of the modified fumed silica to provide different levels of steric hindrance, so that aggregation among fumed silica particles can be prevented; meanwhile, under the action of electrostatic repulsion, the silica particles in the gas phase method are not easy to adsorb each other, and the dispersibility is further improved.

Compared with the prior art, the modified vapor phase method silicon dioxide used in the invention can be attached to the surface of the basalt fiber, and calcium ions and hydroxyl ions in concrete are adsorbed on the surface of the basalt fiber, so that the number of crystal nuclei for generating calcium silicate hydrate gel in the hydration process is increased, the combination of the fiber and the cement matrix is more compact, and the mechanical property of the concrete is improved macroscopically.

Compared with the prior art, the silanol group is introduced into the modified gas-phase method silicon dioxide functional group, and can form one corner of a tetrahedral crystal structure, so that the original two-dimensional crystal structure is improved, and the problem of concrete layering is solved; the silanol group also has the characteristic of easily forming hydrogen bonds, and adjacent particles can form the hydrogen bonds, so that the salt resistance of the concrete is further improved.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

Some raw material parameters in the comparative examples and examples of the invention are as follows:

tetramethyl m-xylylene diisocyanate, CAS No.: 2778-42-9;

n-heptyl isocyanate, CAS No.: 4747-81-3;

2-naphthyl isocyanate, CAS No.: 2243-54-1;

mercaptopropyl methyldimethoxysilane, CAS number: 31001-77-1;

benzoin dimethyl ether, CAS No.: 24650-42-8.

Example 1

The green high-performance cement concrete is prepared by adopting the following method:

s1, sequentially adding 480kg of P.O 42.5 ordinary portland cement, 480kg of medium sand and 1050kg of broken stones into 190kg of water, and mixing at a stirring speed of 25.5rpm for 1h to obtain concrete coarse materials for later use;

s2, continuously and sequentially adding 1.2kg of basalt fibers with the length of 2mm, 15kg of high-dispersion gas-phase method silicon dioxide and 6.5kg of polycarboxylic acid high-performance water reducing agent into the concrete coarse material obtained in the step S1, and mixing for 2 hours at the stirring speed of 35rpm to obtain concrete mortar for later use;

s3, carrying out construction pouring, curing and watering curing on the concrete mortar obtained in the step S2, wherein the curing times are 3 times/day, and the curing period is 28 days, so as to obtain the green high-performance cement concrete.

The gravel is continuous graded gravel and is prepared from 5-10 mm gravel, 10-20 mm gravel and 20-31.5 mm gravel in a mass ratio of 1: 2: 1 is obtained by blending.

The preparation method of the high-dispersion gas-phase method silicon dioxide comprises the following steps:

x1 soaking 6kg of fumed silica in 100kg of 0.5mol/L hydrochloric acid for 2h to obtain acidified fumed silica for later use;

x2 acidified fumed silica was dispersed in 225kg ethanol and diethyl ether in a mass ratio of 4: 1, then adding 15kg of tetramethyl m-xylylene diisocyanate and 2.5kg of n-heptyl isocyanate, and reacting at 85 ℃ for 24 hours under the protection of nitrogen to obtain reaction liquid I for later use;

under the protection of X3 nitrogen, reducing the temperature of the reaction liquid I to 65 ℃, adding 35kg of propylene glycol butyl ether, and continuing to react for 2.5 hours to obtain a reaction liquid II for later use;

adding 0.9kg of 2, 2-bis (hydroxymethyl) malonic acid into the reaction liquid II under the protection of X4 nitrogen, continuously reacting for 2 hours, separating to obtain a solid product, washing with alcohol for 3 times, drying, and crushing to obtain the high-dispersion gas-phase-method silicon dioxide.

Example 2

x2 acidified fumed silica was dispersed in 225kg ethanol and diethyl ether in a mass ratio of 4: 1, then adding 15kg of tetramethyl m-xylylene diisocyanate and 0.8kg of 2-naphthyl isocyanate, and reacting at 85 ℃ for 24 hours under the protection of nitrogen to obtain reaction liquid I for later use;

Example 3

x2 acidified fumed silica was dispersed in 225kg ethanol and diethyl ether in a mass ratio of 4: 1, then adding 2.5kg of n-heptyl isocyanate and 0.8kg of 2-naphthyl isocyanate, and reacting at 85 ℃ for 24 hours under the protection of nitrogen to obtain reaction liquid I for later use;

Example 4

x2 acidified fumed silica was dispersed in 225kg ethanol and diethyl ether in a mass ratio of 4: 1, then adding 15kg of tetramethyl m-xylylene diisocyanate, 2.5kg of n-heptyl isocyanate and 0.8kg of 2-naphthyl isocyanate, and reacting at 85 ℃ for 24 hours under the protection of nitrogen to obtain reaction liquid I for later use;

Example 5

s2, continuously and sequentially adding 1.2kg of basalt fibers with the length of 2mm, 15kg of anti-layering vapor phase method silicon dioxide and 6.5kg of polycarboxylic acid high-performance water reducing agent into the concrete coarse material obtained in the step S1, and mixing for 2 hours at the stirring speed of 35rpm to obtain concrete mortar for later use;

The preparation method of the delamination-proof gas phase method silicon dioxide comprises the following steps:

y1 soaking 6kg of fumed silica in 100kg of 0.5mol/L hydrochloric acid for 2h to obtain acidified fumed silica for later use;

y2 acidified fumed silica was dispersed in 225kg ethanol and diethyl ether in a mass ratio of 4: 1, then adding 15kg of tetramethyl m-xylylene diisocyanate, 2.5kg of n-heptyl isocyanate and 0.8kg of 2-naphthyl isocyanate, and reacting at 85 ℃ for 24 hours under the protection of nitrogen to obtain reaction liquid I for later use;

reducing the temperature of the reaction liquid I to 65 ℃ under the protection of Y3 nitrogen, adding 35kg of propylene glycol butyl ether, and continuing to react for 2.5h to obtain reaction liquid II for later use;

adding 0.9kg of 2, 2-bis (hydroxymethyl) malonic acid into the reaction liquid II under the protection of Y4 nitrogen, continuously reacting for 2 hours, separating to obtain a solid product, washing with alcohol for 3 times, drying, and crushing to obtain high-dispersion fumed silica for later use;

y5 dispersing high-dispersion gas-phase method silicon dioxide in 100kg of N, N-dimethylformamide, then adding 6.5kg of mercaptopropyl-methyldimethoxysilane, reacting at 83 ℃ for 8h, removing the solvent, continuing to react for 2h, separating to obtain a solid product, washing with alcohol for 3 times, washing with water for 3 times, drying, and crushing to obtain a solid product I for later use;

y6 solid product I was dispersed in 45kg of ethanol, 0.4kg of methacrylamide and 0.1kg of benzoin dimethyl ether were added, and the mixture was reacted at 95 ℃ for 2 hours to obtain delamination-proof fumed silica.

Comparative example 1

s2, continuously and sequentially adding 1.2kg of basalt fibers with the length of 2mm, 15kg of fumed silica and 6.5kg of polycarboxylic acid high-performance water reducing agent into the concrete coarse material obtained in the step S1, and mixing at the stirring speed of 35rpm for 2 hours to obtain concrete mortar for later use;

Test example 1

The sulfate resistance test of the green high-performance cement concrete prepared by the invention is carried out according to the specific requirements of GB/T50082-2009 standard section 14 sulfate corrosion resistance test of test method for long-term performance and durability of common concrete. The test specimens used were cubic test pieces having dimensions of 100mm × 100mm × 100mm, and 3 pieces were prepared for each group. The test results were numerically averaged as required, determined and expressed as sulfate resistance rating. The green high performance cement concrete sulfate resistance rating is shown in table 1.

TABLE 1

	Sulfate resistance grade
		Example 1	KS60
Example 2	KS90
		Example 3	KS60
Example 4	KS120
		Example 5	KS150
Comparative example 1	KS30

The higher the sulfate resistance rating, the stronger the sulfate erosion resistance of the concrete. As can be seen from the comparison between the above examples and comparative examples, the fumed silica subjected to the modification treatment can improve the sulfate resistance grade of concrete. The reason for this may be that aggregation between the fumed silica particles can be prevented because the steric hindrance provided by the benzene ring structure and the long and short chains in the modified fumed silica is large; after the functional groups are introduced, the fumed silica particles are not easy to adsorb each other under the action of electrostatic repulsion, the aim of improving the dispersibility is achieved, the highly dispersed fumed silica effectively improves the pore structure of concrete, the diffusion of corrosive salt ions is prevented, and the effect of improving the grade of sulfate resistance is achieved.

Test example 2

The antifreeze performance test of the green high-performance cement concrete is carried out according to the specific requirements of GB/T50082-2009 section 4 antifreeze test of test method standard of long-term performance and durability of common concrete. The freeze resistance test adopts a slow freezing method, the test adopts cubic test pieces with the size of 100mm multiplied by 100mm, and 3 pieces are prepared for each group. The maintenance, test operation and precautions of the sample are carried out according to the procedures in the above-mentioned national standard. The test results are numerically averaged as required, determined and expressed as the frost resistance rating. The results of the green high performance cement concrete frost resistance tests are shown in table 2.

TABLE 2

	Grade of frost resistance
		Example 1	D200
Example 2	D200
		Example 3	D150
Example 4	D250
		Example 5	D300
Comparative example 1	D100

The higher the frost resistance grade of the concrete, the more excellent the frost resistance. As can be seen from the comparison between the above examples and comparative examples, the addition of the modified fumed silica can effectively improve the frost resistance of the concrete. The reason for this is probably that the common gas phase method silicon dioxide has poor dispersibility, is difficult to effectively improve the concrete pore structure, and the moisture is easy to permeate into the matrix through smile gaps in the concrete and cause damage after multiple freeze-thaw cycles; the modified fumed silica has strong dispersibility, can improve the pore structure and effectively prevent the penetration of moisture, so that the moisture in the matrix is less, and the interior of the matrix is not damaged after multiple freezing cycles.

Test example 3

The green high-performance cement concrete compression strength test is carried out according to the specific requirements of GB/T50081 and 2019 section 5 compression strength test of concrete physical and mechanical property test method standard. The samples were prepared in 3 blocks each using a standard cubic sample having a side length of 150 mm. The test is carried out according to the specific steps in the national standard, and the result is averaged according to the requirement. The results of the green high performance cement concrete compression strength tests are shown in table 3.

TABLE 3

	Compressive strength (MPa)
		Example 1	58.5
Example 2	60.6
		Example 3	56.3
Example 4	63.7
		Example 5	68.4
Comparative example 1	53.6

Higher compressive strength of concrete means a higher pressure limit when it is subjected to pressure from an external force. As can be seen from the comparison between the above examples and comparative examples, the addition of the modified fumed silica contributes to the improvement of the compressive strength of concrete. The reason for this is probably that the fumed silica can carry a large amount of concrete hydration products to be attached to the surface of the basalt fiber, and calcium ions and hydroxyl ions in the concrete are adsorbed on the surface of the basalt fiber, so that the number of crystal nuclei for generating hydrated calcium silicate gel in the hydration process is increased, the combination of the fiber and the cement matrix is more compact, and the mechanical property of the concrete is macroscopically improved.

Claims

1. The preparation method of the green high-performance cement concrete is characterized by comprising the following steps of: modifying the gas phase method silicon dioxide, introducing a benzene ring structure and molecular chains with different length gradients to the surface of the gas phase method silicon dioxide, and taking the modified gas phase method silicon dioxide as a raw material of concrete.

2. The method for preparing green high-performance cement concrete according to claim 1, characterized by comprising the following steps:

s1, sequentially adding 480-540 parts by weight of cement, 480-540 parts by weight of medium sand and 1050-1200 parts by weight of broken stone into 190-220 parts by weight of water, and stirring to obtain concrete coarse materials for later use;

s2, continuously and sequentially adding 1.2-8 parts by weight of basalt fibers, 15-36 parts by weight of modified fumed silica and 6.5-13 parts by weight of water reducer into the concrete coarse material obtained in the step S1, and stirring to obtain concrete mortar for later use;

3. The method for preparing green high-performance cement concrete according to claim 2, characterized in that: the gravel is continuous graded gravel and is prepared from 5-10 mm gravel, 10-20 mm gravel and 20-31.5 mm gravel in a mass ratio of 1: 2: 1 is obtained by blending.

4. The method for preparing green high-performance cement concrete according to claim 2, characterized in that: the modified gas phase method silicon dioxide is any one of high dispersion gas phase method silicon dioxide and anti-layering gas phase method silicon dioxide.

5. The method for preparing green high-performance cement concrete according to claim 4, wherein the method for preparing the high-dispersion fumed silica comprises the following steps:

6. The method for preparing green high-performance cement concrete according to claim 5, wherein the acidification treatment in the step X1 is as follows according to the parts by weight: 5-8 parts of fumed silica are taken and placed in 75-125 parts of hydrochloric acid with the concentration of 0.1-0.5 mol/L for soaking for 1-3 h.

7. The method for preparing green high-performance cement concrete according to claim 5, characterized in that: the usage amount of the mixture formed by the ethanol and the diethyl ether in the step X2 is 150-300 parts by weight, wherein the mass ratio of the ethanol to the diethyl ether is 4: 1; the using amount of the tetramethyl m-xylylene diisocyanate is 8-24 parts; the using amount of the n-heptyl isocyanate is 1.5-5 parts; the using amount of the 2-naphthyl isocyanate is 0.3-1.2 parts.

8. The method for preparing green high-performance cement concrete according to claim 5, which is characterized in that: the using amount of the propylene glycol butyl ether in the step X3 is 24-56 parts by weight.

9. The method for preparing green high-performance cement concrete according to claim 5, which is characterized in that: the using amount of the 2, 2-bis (hydroxymethyl) malonic acid in the step X4 is 0.4-2 parts.

10. The green high-performance cement concrete is characterized in that: prepared by the method of any one of claims 1 to 9.