CN111362636A - C60 carbon fiber concrete and preparation method thereof - Google Patents

Abstract

The invention discloses C60 carbon fiber concrete which is prepared from the following raw materials in parts by weight: 390 parts of cement 370-containing material, 170 parts of water 150-containing material, 710 parts of river sand 690-containing material, 1080 parts of crushed stone 1060-containing material, 7-9 parts of carbon fiber, 80-125 parts of fly ash, 40-60 parts of silica fume, 6-8 parts of water reducing agent, 9-10 parts of shrinkage reducing agent, 10-12 parts of exciting agent, 0.9-1.2 parts of dispersing agent and 0.6-0.7 part of defoaming agent; and provides a preparation method thereof. The concrete overcomes the defects of high brittleness, easy cracking, uneven carbon fiber distribution and the like of high-strength carbon fiber concrete by utilizing materials which are easily available in the market, adopting an improved concrete stirring process and adding silica fume, fly ash, hydroxypropyl methyl cellulose, a chemical additive and the like so as to prepare the carbon fiber concrete with the C60 strength grade, which has excellent workability, high volume stability and higher ductility.

Description

C60 carbon fiber concrete and preparation method thereof

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to C60 carbon fiber concrete and a preparation method thereof.

Background

The concrete with higher strength grade has more brittleness and more serious dry shrinkage, and the addition of a certain amount of carbon fiber in the high-strength concrete can improve the compression strength, the tensile strength, the bending strength and the impact resistance of the high-strength concrete and reduce the dry shrinkage and the brittleness. On the other hand, as an excellent structural material, high reinforcement is an inevitable direction of development of carbon fiber concrete.

Although the addition of carbon fibers to high-strength concrete has great advantages, the carbon fibers are not uniformly dispersed, and the mechanical properties such as compressive strength and tensile strength are reduced due to excessive addition of the carbon fibers. In addition, the incorporation of carbon fibers will also result in a reduction in the workability of the concrete.

Disclosure of Invention

The first purpose of the present invention is to solve the problems of high strength concrete, and provide a carbon fiber concrete with a grade strength of C60, which utilizes materials available in the market, adopts an improved concrete stirring process, and overcomes the disadvantages of high brittleness, easy cracking, uneven carbon fiber distribution and the like of the high strength carbon fiber concrete by adding silica fume, fly ash, hydroxypropyl methyl cellulose, chemical additives and the like, so as to prepare the carbon fiber concrete with a C60 strength grade, which has excellent workability, high volume stability and high ductility.

The second purpose of the invention is to provide a preparation method of the concrete.

The purpose of the invention is realized by the following technical scheme:

the C60 carbon fiber concrete is prepared from the following raw materials in parts by weight:

390 portions of cement 370-containing material, 170 portions of water 150-containing material, 710 portions of river sand 690-containing material, 1080 portions of crushed stone 1060-containing material, 7-9 portions of carbon fiber, 80-125 portions of fly ash, 40-60 portions of silica fume, 6-8 portions of water reducing agent, 9-10 portions of shrinkage reducing agent, 10-12 portions of exciting agent, 0.9-1.2 portions of dispersing agent and 0.6-0.7 portion of defoaming agent.

Preferably, the concrete is prepared from the following raw materials in parts by weight:

383 parts of cement, 164 parts of water, 702 parts of river sand, 1070 parts of gravel, 8 parts of carbon fiber, 100 parts of fly ash, 45 parts of silica fume, 7.2 parts of a water reducing agent, 9.6 parts of a shrinkage reducing agent, 11 parts of an exciting agent, 1.1 parts of a dispersing agent and 0.62 part of a defoaming agent.

More preferably, the cement is P.O42.5-grade ordinary portland cement with good compatibility with a polycarboxylic acid water reducing agent;

the river sand is medium sand meeting the GB/T14684-2001 grading 2 area;

the crushed stone is selected from artificial crushed stones which are good in grading, compact, hard and rough in surface and mainly comprise granite and basalt, the particle size range is 5-20mm, and grading is carried out according to continuous particle size;

the fly ash is I-grade ultra-fine fly ash of GB/T1596-;

the silica fume is silica fume which accords with GB/T18736-2002;

the water reducing agent is a polycarboxylic acid standard type high-performance water reducing agent which meets GB 8076-2008;

the shrinkage reducing agent is BT-5001 type shrinkage reducing agent;

the excitant consists of analytically pure anhydrous sodium sulfate and hydrated lime powder in a weight ratio of 1:7, and the purity of the anhydrous sodium sulfate is 99%;

the dispersant is hydroxypropyl methylcellulose with density of 1.39g/cm³The 100-mesh passing rate is more than 98.5 percent, the carbonization temperature is 280-300 ℃, and the viscosity is more than 15W;

the defoaming agent adopts tributyl phosphate, the density of the tributyl phosphate at 20 ℃ is between 0.974 and 0.980g/ml, and the acidity is H⁺Calculated by less than or equal to 0.2Percent, water content is less than or equal to 0.1 percent.

More preferably, the carbon fiber is T300 carbon fiber, the length is 7mm, the specification is 3K, the tensile strength is 3530MPa, the tensile modulus is 230GPa, and the density is 1.78g/cm³The elongation was 1.5%, the diameter was 7 μm, and the carbon content was 93%.

The preparation method of the C60 carbon fiber concrete specifically comprises the following steps:

(1) weighing cement, pebbles, river sand, fly ash, silica fume, a water reducing agent, a shrinkage reducing agent and an exciting agent according to a ratio, putting the raw materials into a stirrer at the same time, dry-stirring for 3-4min, weighing 30% of water, adding into the stirrer, and stirring for 4-5min to prepare a wet material;

(2) heating the rest 70% of water to 60 ℃, weighing the dispersing agent, and putting the dispersing agent into the water for dispersing and dissolving to obtain a dispersing solution; adding carbon fibers into the dispersion liquid, and stirring until the carbon fibers are completely dispersed;

(3) adding a defoaming agent into the carbon fiber dispersion liquid obtained in the step (2), and continuing stirring until bubbles on the surface of the dispersion liquid disappear;

(4) pouring the carbon fiber dispersion liquid obtained in the step (3) into a stirrer, and stirring the carbon fiber dispersion liquid and the wet material obtained in the step (1) for 4-5min to form a carbon fiber concrete mixture;

(5) and (4) pouring the concrete mixture obtained in the step (4) into a cast iron mold for molding and tapping, placing in an environment with the temperature of 20 +/-2 ℃, covering wet geotextile on the surface of a test block, standing for 1 day, removing the mold, and then curing in a standard curing room to the required age.

According to the invention, the brittleness of high-strength concrete is overcome by adopting carbon fibers, and the mechanical properties such as compressive strength, breaking strength and the like of the concrete are ensured by adopting a reasonable carbon fiber mixing amount; in order to disperse the carbon fibers more uniformly in the concrete slurry, Hydroxypropylmethylcellulose (HPMC) is used as a dispersant; the workability, strength and durability of the carbon fiber concrete are improved by doping the fly ash and the silica fume; by adding the shrinkage reducing agent into the concrete, the shrinkage of the concrete can be controlled and reduced, tiny pores in the concrete are filled, and the strength of the concrete is improved; in addition, the volcanic ash activity of the fly ash in the low water-cement ratio concrete can be effectively excited by adding the sodium sulfate and the hydrated lime powder as the exciting agents. According to the invention, through the synergistic effect among the components, the cementing material is more fully hydrated, the microcosmic composition in the concrete is improved, the number of harmful pores is reduced, the internal structure of the concrete is more compact, and the carbon fiber concrete material with high strength, high ductility, high durability and good workability is finally prepared.

The invention has the following beneficial effects:

(1) the reasonable carbon fiber mixing amount is adopted to ensure the mechanical properties of the concrete, such as the compressive strength, the breaking strength and the like. A large number of experimental studies show that: the mechanical properties such as the compressive strength, the rupture strength and the like of the carbon fiber concrete are the law of increasing and then reducing along with the increase of the carbon fiber doping amount, and the carbon fiber doping amount needs to be reasonably selected for ensuring the strength of the carbon fiber concrete.

Hydroxypropyl methyl cellulose (HPMC) is used as a dispersing agent of the carbon fiber, the hydroxypropyl methyl cellulose has more polar groups, hydrogen bonds are formed with polar water molecules, and simultaneously a monomolecular film and spherical micelles are formed on the surface and inside of the liquid, so that the area between water and air is reduced, the surface tension of the solution is rapidly reduced, the hydrophilicity and the wettability of the carbon fiber are increased, the dispersibility of the carbon fiber is improved, and a colloid-like dispersion system is formed.

(2) The fly ash and the silica fume are mixed, so that the filling effect, the volcanic ash effect and the micro-aggregate effect of the fly ash and the silica fume are effectively exerted, and the mutual complementary effect of the fly ash and the silica fume improves the interface bonding of cement-based aggregate and cement-based carbon fiber, reduces the pore size, reduces the number of harmful pores, and makes the internal structure of the concrete more compact.

(3) The shrinkage reducing agent can reduce the surface tension of water in the concrete to reduce the capillary tension in the concrete, thereby greatly reducing the dry shrinkage, volume shrinkage, early plastic shrinkage of hardening and the like of the concrete.

(4) The analytically pure anhydrous sodium sulfate-hydrated lime powder composite exciting agent can provide more OH^-、Ca²⁺、SO₄ ^2-Can accelerate the active SiO in the fly ash₂、Al₂O₃The reaction speed greatly increases the amount of rod-shaped hydration products, namely ettringite, so that the hydration speed and the hydration process of a fly ash-cement system are accelerated, and the early strength of the concrete is improved.

Detailed Description

The following description of the preferred embodiments of the present invention is provided for the purpose of illustration and description, and is in no way intended to limit the invention.

Raw materials;

1. cement

The cement is ordinary Portland cement, the strength grade is P.O 42.5.5, and the density is 3100kg/m³. Through inspection, all technical indexes of the cement meet the requirements of GB 175-: specific surface area not less than 300m²/kg, loss on ignition not more than 5%, SO₃The content should be not more than 3.5%, MgO₂The content is not more than 5%, the content of chloride ions is not more than 0.06%, the content of alkali is not more than 0.6%, the initial setting time is not less than 45min, the final setting time is not more than 600min, the 3-day strength is not less than 17MPa, and the 28-day strength is not less than 42.5 MPa.

Before use, the polycarboxylic acid standard high-performance water reducing agent is subjected to adaptability test between the polycarboxylic acid standard high-performance water reducing agent and the polycarboxylic acid standard high-performance water reducing agent, and the test method adopts a method in the existing building material industry standard JC/T1083-plus 2008 to finally determine that the polycarboxylic acid standard high-performance water reducing agent and the polycarboxylic acid standard high-performance water reducing agent have good compatibility.

2. Fine aggregate

The fine aggregate is natural river sand which is medium sand with apparent density of 2730kg/m³The content of the mud blocks is 0.1 percent, the mud content is 0.6 percent, the fineness modulus is 2.7, and the requirement of the GB/T14684-2001 grading 2 area is met. Through inspection, the quality of the sand meets the high-quality sand standard specified in the current building material industry standard 'quality of common concrete sand and stone and inspection method standard' JC/T52-2006 and the national standard 'Sand for building' GB/T14684-2001.

3. Coarse aggregate

The coarse aggregate adopts artificial macadam, has compact and hard mass and rough surface, and has apparent density of 2700kg/m³. The main components of the brick are granite and basalt, the content (by mass) of the main components is not less than 90%, the mud content is not more than 1%, the mud block content is not more than 0.5%, and the sulfide and sulfate content is not more than 1%. The grain shape is approximately spherical, the content of needles and flakes is small, the nominal grain size range is between 5 and 40mm, and the continuous gradation meets the requirements of table 3.2.1-2 in the standard of quality and inspection method for sand and stone for common concrete JGJ 52-2006.

4. Water (W)

The water is tap water, and the quality of the tap water meets the requirements of national standard JGJ 63-2006: pH value not less than 4.5, insoluble matter content not more than 2000mg/L, soluble matter content not more than 5000mg/L, and Cl^-The content is not more than 1000mg/L, SO₄ ^2-The content is not more than 2000mg/L, and the alkali content is not more than 1500 rag/L.

5. Fly ash

Adopts I-grade superfine fly ash with the density of 2400kg/m³. Through inspection, various standards of the fly ash meet the requirements of national standard 'fly ash used in cement and concrete' GB/T1596-2005: the screen residue of a 0.045mm square-hole screen is not more than 10 percent, the ignition loss is not more than 3 percent, and the SO₃The content should be not more than 2%, the water content should be not more than 1%, the water demand ratio should be not more than 95%, and the specific surface area should be more than 700m²/kg。

6. Silica fume

The apparent density of the powder is 2200kg/m³The quality of the concrete meets the requirements of the national standard of mineral admixture for high-strength and high-performance concrete GB/T18736-2002 and other related standards: loss on ignition of not more than 6%, SO₂The content is not less than 85%, the content of chloride ion is not more than 0.02%, the water content is not more than 3%, and the specific surface area is not less than 15000m²/kg, water requirement ratio not more than 125%, activity index (28d) not less than 85%.

7. High-efficiency water reducing agent

Adopts a polycarboxylic acid standard high-performance water reducing agent with the apparent density of 1070kg/m³The water reducing rate is 32%, the content of chloride ions is not more than 0.6%, the content of sodium sulfate is not more than 5%, the content of alkali is not more than 10%, the content of formaldehyde is not more than 0.05%, and the gas content isNot more than 6 percent, and the pH value is between 6 and 7, and the quality meets the requirements of the related standards of the existing national standard of concrete admixture GB 8076-2008 and the like.

8. Shrinkage reducing agent

Adopts sea charm BT-5001 type shrinkage reducing agent.

9. Exciting agent

An analytically pure anhydrous sodium sulfate-hydrated lime powder composite exciting agent is adopted, and the weight ratio of the anhydrous sodium sulfate to the hydrated lime powder is 1:7, the purity of the anhydrous sodium sulfate is 99%.

10. Dispersing agent

Hydroxypropyl methylcellulose (HPMC) is used as a dispersing agent, and the density is 1.39g/cm³The 100-mesh passing rate is more than 98.5 percent, the carbonization temperature is 280-300 ℃, and the viscosity is 20W.

11. Defoaming agent

Tributyl phosphate is adopted as an antifoaming agent, the density (20 ℃) of the tributyl phosphate is between 0.974 and 0.980g/ml, and the acidity (H) is⁺Calculated) is less than or equal to 0.2 percent, and the water content is less than or equal to 0.1 percent.

12. Carbon fiber

The T300 carbon fiber is adopted, the length is 7mm, and the indexes of other parameters are shown in Table 1.

TABLE 1 carbon fiber parameter index

Manufacturing and maintaining a test piece:

(1) weighing cement, pebbles, river sand, fly ash, silica fume, a water reducing agent, a shrinkage reducing agent and an exciting agent according to a ratio, putting the raw materials into a stirrer at the same time, dry-stirring for 3min, weighing 30% of water, adding into the stirrer, stirring for 5min, and preparing into a wet material.

(2) Heating the residual 70% of water to 60 ℃, weighing the dispersing agent, and putting the dispersing agent into the water for dispersing and dissolving to obtain a dispersion liquid; adding carbon fibers into the dispersion, and stirring until the carbon fibers are completely dispersed.

(3) And (3) adding a defoaming agent into the carbon fiber dispersion liquid obtained in the step (2), and continuing stirring until bubbles on the surface of the dispersion liquid disappear.

(4) And (4) pouring the carbon fiber dispersion liquid obtained in the step (3) into a stirrer, and stirring the carbon fiber dispersion liquid and the concrete wet material obtained in the step (1) for 5min to form a carbon fiber concrete mixture.

(5) Pouring the concrete mixture obtained in the step (4) into a 150mm × 150mm × 150mm cast iron mold for molding and tapping, placing in an environment with the temperature of 20 +/-2 ℃, covering wet geotextile on the surface of a test block, standing for 1 day, removing the mold, and then curing in a standard curing room for 28 days.

Example 1

In the carbon fiber concrete with the strength grade of C60 in the embodiment, the ratio of the components in the carbon fiber concrete by weight is as follows: 383 parts of cement, 164 parts of water, 702 parts of river sand, 1070 parts of gravel, 8 parts of carbon fiber, 100 parts of fly ash, 45 parts of silica fume, 7.2 parts of a water reducing agent, 9.6 parts of a shrinkage reducing agent, 11 parts of an exciting agent, 1.1 parts of a dispersing agent and 0.62 part of a defoaming agent.

Example 2

In the carbon fiber concrete with the strength grade of C60 in the embodiment, the ratio of the components in the carbon fiber concrete by weight is as follows: 370 parts of cement, 150 parts of water, 690 parts of river sand, 1060 parts of crushed stone, 7 parts of carbon fiber, 80 parts of fly ash, 40 parts of silica fume, 6 parts of water reducing agent, 9 parts of shrinkage reducing agent, 10 parts of exciting agent, 0.9 part of dispersing agent and 0.6 part of defoaming agent.

Example 3

In the carbon fiber concrete with the strength grade of C60 in the embodiment, the ratio of the components in the carbon fiber concrete by weight is as follows: 390 parts of cement, 170 parts of water, 710 parts of river sand, 1080 parts of crushed stone, 9 parts of carbon fiber, 125 parts of fly ash, 60 parts of silica fume, 8 parts of water reducing agent, 10 parts of shrinkage reducing agent, 12 parts of exciting agent, 1.2 parts of dispersing agent and 0.7 part of defoaming agent.

Testing

Slump test method: filling carbon fiber concrete into a horn-shaped slump bucket with an upper opening of 100mm, a lower opening of 200mm and a height of 300mm for three times, uniformly beating 25 times from outside to inside along the wall of the bucket by a tamping hammer after each filling, tamping and leveling. And then pulling up the barrel, wherein the concrete generates a collapse phenomenon due to self weight, and the height of the highest point of the carbon fiber concrete after the collapse is subtracted from the barrel height (300mm), namely the slump.

According to the requirements in the standard of ordinary concrete mechanical property test method (GB/T50081-2002), a microcomputer electro-hydraulic servo pressure tester with the HYE-2000 model is adopted to carry out the compression strength and the splitting tensile test on the test piece, and the test is continuously and uniformly loaded at the speed of 0.5MPa/s and the speed of 0.05MPa/s respectively until the test piece is damaged.

Table 2C 60 strength grade carbon fiber concrete test results

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. The C60 carbon fiber concrete is characterized by being prepared from the following raw materials in parts by weight:

390 portions of cement 370-containing material, 170 portions of water 150-containing material, 710 portions of river sand 690-containing material, 1080 portions of crushed stone 1060-containing material, 7-9 portions of carbon fiber, 80-125 portions of fly ash, 40-60 portions of silica fume, 6-8 portions of water reducing agent, 9-10 portions of shrinkage reducing agent, 10-12 portions of exciting agent, 0.9-1.2 portions of dispersing agent and 0.6-0.7 portion of defoaming agent.

2. The C60 carbon fiber concrete according to claim 1, wherein the concrete is prepared from the following raw materials in parts by weight:

383 parts of cement, 164 parts of water, 702 parts of river sand, 1070 parts of gravel, 8 parts of carbon fiber, 100 parts of fly ash, 45 parts of silica fume, 7.2 parts of a water reducing agent, 9.6 parts of a shrinkage reducing agent, 11 parts of an exciting agent, 1.1 parts of a dispersing agent and 0.62 part of a defoaming agent.

3. The C60 carbon fiber concrete according to claim 1 or 2, wherein the cement is P.O 42.5.5-grade ordinary portland cement with good compatibility with a polycarboxylic acid water reducer;

the river sand is medium sand meeting the GB/T14684-2001 grading 2 area;

the crushed stone is selected from artificial crushed stones which are good in grading, compact, hard and rough in surface and mainly comprise granite and basalt, the particle size range is 5-20mm, and grading is carried out according to continuous particle size;

the fly ash is I-grade ultra-fine fly ash of GB/T1596-;

the silica fume is silica fume which accords with GB/T18736-2002;

the water reducing agent is a polycarboxylic acid standard type high-performance water reducing agent which meets GB 8076-2008;

the shrinkage reducing agent is BT-5001 type shrinkage reducing agent;

the excitant consists of analytically pure anhydrous sodium sulfate and hydrated lime powder in a weight ratio of 1:7, and the purity of the anhydrous sodium sulfate is 99%;

the dispersant is hydroxypropyl methylcellulose with density of 1.39g/cm³The 100-mesh passing rate is more than 98.5 percent, the carbonization temperature is 280-300 ℃, and the viscosity is more than 15W;

the defoaming agent adopts tributyl phosphate, the density of the tributyl phosphate at 20 ℃ is between 0.974 and 0.980g/ml, and the acidity is H⁺Less than or equal to 0.2 percent and less than or equal to 0.1 percent of water.

4. The C60 carbon fiber concrete according to claim 1 or 2, wherein the carbon fibers are T300 carbon fibers, have a length of 7mm, a specification of 3K, a tensile strength of 3530MPa, a tensile modulus of 230GPa, and a density of 1.78g/cm³The elongation was 1.5%, the diameter was 7 μm, and the carbon content was 93%.

5. The method for preparing C60 carbon fiber concrete according to any one of claims 1 to 4, which comprises the following steps:

(1) weighing cement, pebbles, river sand, fly ash, silica fume, a water reducing agent, a shrinkage reducing agent and an exciting agent according to a ratio, putting the raw materials into a stirrer at the same time, dry-stirring for 3-4min, weighing 30% of water, adding into the stirrer, and stirring for 4-5min to prepare a wet material;

(2) heating the rest 70% of water to 60 ℃, weighing the dispersing agent, and putting the dispersing agent into the water for dispersing and dissolving to obtain a dispersing solution; adding carbon fibers into the dispersion liquid, and stirring until the carbon fibers are completely dispersed;

(3) adding a defoaming agent into the carbon fiber dispersion liquid obtained in the step (2), and continuing stirring until bubbles on the surface of the dispersion liquid disappear;

(4) pouring the carbon fiber dispersion liquid obtained in the step (3) into a stirrer, and stirring the carbon fiber dispersion liquid and the wet material obtained in the step (1) for 4-5min to form a carbon fiber concrete mixture;

(5) and (4) pouring the concrete mixture obtained in the step (4) into a cast iron mold for molding and tapping, placing in an environment with the temperature of 20 +/-2 ℃, covering wet geotextile on the surface of a test block, standing for 1 day, removing the mold, and then curing in a standard curing room to the required age.