CN112745085A

CN112745085A - Sprayable PVA-ECC (polyvinyl acetate-ECC) high-ductility cement-based composite material and preparation method thereof

Info

Publication number: CN112745085A
Application number: CN202110202016.0A
Authority: CN
Inventors: 谷音; 孙颖; 黄新艺; 晁鹏飞; 毛贵军
Original assignee: Fuzhou University; Fujian Yongzheng Construction Quality Inspection Co Ltd
Current assignee: Fuzhou University; Fujian Yongzheng Construction Quality Inspection Co Ltd
Priority date: 2021-02-23
Filing date: 2021-02-23
Publication date: 2021-05-04
Also published as: ZA202110195B

Abstract

The invention belongs to the technical field of composite materials, and discloses a sprayable PVA-ECC (polyvinyl acetate-ECC) high-ductility cement-based composite material and a preparation method thereof, wherein the sprayable PVA-ECC high-ductility cement-based composite material consists of 10 parts by mass of a cementing material, 5 parts by mass of fine quartz sand, 0.003-0.006 part by mass of cellulose HPMC (hydroxy propyl methyl cellulose), 0.02-0.1 part by mass of a water reducing agent, 0.17-0.23 part by mass of PVA fiber and 2.8-3 parts by mass of water, wherein the PVA fiber accounts for 1.5-2% of the sprayable PVA-ECC high-ductility cement-based composite material. The sprayable ECC disclosed by the invention has higher impermeability and chemical corrosion resistance, and the rebound rate of concrete is controlled within 5%. The sprayable ECC has excellent mechanical property, the compressive strength can reach 50MPa, the uniaxial tensile strain is 3-5%, and the sprayable ECC has obvious multi-crack cracking phenomenon and strain hardening.

Description

Sprayable PVA-ECC (polyvinyl acetate-ECC) high-ductility cement-based composite material and preparation method thereof

Technical Field

The invention belongs to the technical field of composite materials, and particularly relates to a sprayable PVA-ECC (polyvinyl alcohol-ECC) high-ductility cement-based composite material and a preparation method thereof.

Background

At present, common concrete materials have the defects of low tensile strength, poor toughness, easy cracking and difficulty in controlling the width of a cracked crack. The existence of the cracks reduces the bearing capacity of the material on one hand, so that the material is damaged under the stress action of not reaching the limit load, and the structure loses the effect. On the other hand, the corrosion channel is provided for harmful media, the damage of the structure is accelerated, and the durability of the structure is reduced.

Most of infrastructure projects built in early stage of China enter or are about to enter an aging stage, and a large number of projects need to be repaired and reinforced. Repairing and reinforcing these projects also place more stringent requirements on the material properties of the concrete, particularly toughness, ductility, durability, and crack control capability.

Therefore, the research on the cement-based composite material with high performance, high durability and multiple applicability is significant. For the enhancement of concrete toughness, however, the traditional fiber reinforced cement-based composite material has the characteristic of strain softening. The prior art provides a basic design concept of a novel engineering cement-based composite material through a mesomechanics and fracture mechanics basic principle, and consciously adjusts fibers, a matrix and a fiber matrix interface. The ultimate tensile strain of the material can reach more than 3 percent, is hundreds times of that of common concrete, and has the strain hardening characteristic similar to that of metal. The existing ECC material mainly adopts PE and PVA fibers, and the fibers cause high cost of the ECC material and are not beneficial to large-area popularization in engineering.

Through the above analysis, the problems and defects of the prior art are as follows:

(1) the existing composite material has poor flowability, easy pipe blockage during spraying, strain softening, incapability of quickly condensing after spraying, low durability, low toughness and low crack control capability.

(2) The main reason for limiting the popularization of ECC engineering is high cost, the fiber is the main reason for high price in the material, the daily PVA fiber is high in economic cost, and the domestic fiber can reduce the cost.

The difficulty in solving the above problems and defects is: (1) the daily-produced fiber is subjected to oiling treatment and hydrophobicity, so that the chemical bonding force between the fiber and a matrix is weak, the matrix and the fiber slowly fall off when being separated under stress, and the toughness of the composite material can be increased. The toughness of the concrete is increased, the development of cracks can be controlled, and the durability of the concrete structure is facilitated. (2) The fiber with the length of 8mm is adopted to replace the fiber with the length of 12mm, the fluidity of the mixture is improved, the mixture is easy to spray, the problem of pipe blockage caused by spraying can be solved, and the mechanical property is not attenuated much.

The significance of solving the problems and the defects is as follows: shotcrete is a type of concrete that is set and hardened by a shotcrete machine by using high pressure to transport the concrete through a pipe and spraying it at high speed onto a surface to be reinforced. The spraying construction saves the procedures of formwork erecting, pouring and formwork removing, can save manpower and shorten the construction period, and the sprayable ECC with high toughness and spraying construction is an excellent reinforcing material.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a sprayable PVA-ECC high-ductility cement-based composite material and a preparation method thereof.

The invention is realized in such a way that the sprayable PVA-ECC high-ductility cement-based composite material is composed of, by mass, 10 parts of a cementing material, 5 parts of fine quartz sand, 0.03-0.06 part of cellulose HPMC, 0.02-0.1 part of a water reducing agent, 0.17-0.23 part of PVA fiber and 2.8-3 parts of water.

The PVA fiber accounts for 1.5-2% of the sprayable PVA-ECC high-ductility cement-based composite material.

Furthermore, the cementing material consists of 25-65% of Portland cement, 30-65% of fly ash and 5-10% of high-age soil.

Further, the portland cement is 42.5-grade portland cement; the apparent density is 3150kg/m3, and the specific surface area is 352m 2/kg; the loss on ignition is not more than 5.0 percent, the initial setting time is 1 hour, and the final setting time is 3 hours.

Further, the fly ash is first-grade F-type low-calcium fly ash, and the mass content of free calcium oxide in the fly ash is less than 1%.

Further, the super-aged soil is active super-aged soil calcined at 750 ℃, and the fineness is 1250 meshes.

Further, the fineness of the fine quartz sand is 100-200 meshes, and the content of silicon dioxide in the fine quartz sand is not less than 99%.

Further, the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 25%.

Further, the PVA fiber had an ultimate tensile strength of 1550MPa, an elongation of 6.3%, an elastic modulus of 39GPa, and a density of 1.3g/cm³The diameter was 39 μm and the length was 8 mm.

In the invention, the cost of the domestic fiber is lower, and the 8mm short fiber is beneficial to spraying; the large amount of fly ash is beneficial to the slippage and falling of the fiber and the matrix, and the toughness of the composite material is increased.

Another object of the present invention is to provide a method for preparing a sprayable PVA-ECC high ductility cement-based composite material, comprising:

weighing portland cement, fly ash, kaolin, HPMC, fine quartz sand, water, a water reducing agent and PVA fiber in proportion;

putting the weighed portland cement, fly ash, kaolin, HPMC and fine quartz sand into a stirrer, and slowly dry-stirring for 2 minutes at the rotating speed of the stirrer of 140 +/-5 r/min to obtain a mixture A;

step three, uniformly mixing water and a water reducing agent in proportion, adding the mixture into the mixture A, and slowly stirring for 3 minutes at the rotating speed of a stirrer of 140 +/-5 r/min to obtain a mortar matrix with certain fluidity;

dispersing the PVA fiber, and slowly adding the dispersed PVA fiber along the rotation direction of a blade of a stirrer, wherein the rotation speed of the stirrer is 285 +/-10 r/min;

and step five, stirring for 5-8 minutes in combination with the fiber dispersion condition to obtain the PVA-ECC mixture with well-dispersed fibers.

By combining all the technical schemes, the invention has the advantages and positive effects that: the sprayable ECC disclosed by the invention has higher impermeability and chemical corrosion resistance, and the rebound rate of concrete is controlled within 5%. The sprayable ECC has excellent mechanical property, the compressive strength can reach 50MPa, the uniaxial tensile strain is 3-5%, and the sprayable ECC has obvious multi-crack cracking phenomenon and strain hardening.

The high-ductility cement-based composite material is prepared by using the technical scheme of replacing the daily PVA fiber with the domestic 8mm PVA, the cost of the ECC material is obviously reduced, the high-ductility cement-based composite material has excellent mechanical properties, the compressive strength can reach 40-50 MPa, and the uniaxial tensile strain can reach 5%; the toughness is obviously enhanced.

The fly ash is waste material produced by power plant, and can reduce environmental pollution, raise the reutilization rate of fly ash when it is used in concrete, and can reduce the economic cost of spraying ECC when it is used to replace cement.

Technical effect or experimental effect of comparison.

From the current material price on the market, the cost of PVA-ECC produced per cubic day is about 3 times of that of the domestic PVA-ECC.

The tensile strain of the substrate without the fibers is only 0.03 percent, the tensile strain of the PVA-ECC with the size of 12mm is 4.0 percent, the tensile strain of the PVA-ECC with the size of 8mm is 2.8-4.2 percent, and the toughness of the PVA-ECC with the size of 8mm is obviously improved relative to the toughness of the fibers, and compared with the PVA with the size of 12mm, the toughness of the PVA-ECC with the size of 8mm is not obviously weakened, and on the contrary, the flowability of the mixture with the size of 12mm is obviously improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained from the drawings without creative efforts.

FIG. 1 is a flow chart of a method for preparing a sprayable PVA-ECC high-ductility cement-based composite material according to an embodiment of the invention.

FIG. 2 is a tensile stress-strain curve of the test piece of example 2 provided in the example of the present invention.

FIG. 3 is a tensile stress-strain curve of the test piece of example 3 provided by the example of the present invention.

FIG. 4 is a tensile stress-strain curve of the test piece of example 4 provided by the example of the present invention.

FIG. 5 is a tensile stress-strain curve of the test piece of example 5 provided in the example of the present invention.

FIG. 6 is a tensile stress-strain curve of the test piece of example 6 provided by the example of the present invention.

FIG. 7 is a tensile stress-strain curve of the test piece of example 7 provided by the example of the present invention.

FIG. 8 is a tensile stress-strain curve of a test piece of example 8 provided by an example of the present invention

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Aiming at the problems in the prior art, the invention provides a sprayable PVA-ECC high-ductility cement-based composite material and a preparation method thereof, and the invention is described in detail below with reference to the accompanying drawings.

The sprayable PVA-ECC high-ductility cement-based composite material provided by the embodiment of the invention comprises, by mass, 10 parts of a cementing material, 5 parts of fine quartz sand, 0.03-0.06 part of cellulose HPMC, 0.02-0.1 part of a water reducing agent, 0.17-0.23 part of PVA fiber and 2.8-3 parts of water

The PVA fiber provided by the embodiment of the invention accounts for 1.5-2% of the sprayable PVA-ECC high-ductility cement-based composite material.

The cementing material provided by the embodiment of the invention consists of 25-65% of Portland cement, 30-65% of fly ash and 5-10% of higher age soil.

The portland cement provided by the embodiment of the invention is 42.5-grade portland cement; the apparent density is 3150kg/m3, and the specific surface area is 352m 2/kg; the loss on ignition is not more than 5.0 percent, the initial setting time is 1 hour, and the final setting time is 3 hours.

The fly ash provided by the embodiment of the invention is first-grade F-type low-calcium fly ash, and the mass content of free calcium oxide in the fly ash is less than 1%.

The super-aged soil provided by the embodiment of the invention is active super-aged soil calcined at 750 ℃, and the fineness is 1250 meshes.

The fineness of the fine quartz sand provided by the embodiment of the invention is 100-200 meshes, and the content of silicon dioxide in the fine quartz sand is not less than 99%.

The water reducing agent provided by the embodiment of the invention is a polycarboxylic acid water reducing agent, and the water reducing rate is 25%.

The PVA fiber provided by the embodiment of the invention has the ultimate tensile strength of 1550MPa, the elongation of 6.3 percent, the elastic modulus of 39GPa and the density of 1.3g/cm³The diameter was 39 μm and the length was 8 mm.

As shown in fig. 1, a preparation method of a sprayable PVA-ECC high ductility cement-based composite material provided by the embodiment of the invention comprises the following steps:

s101, weighing portland cement, fly ash, super-kaolin, HPMC, fine quartz sand, water, a water reducing agent and PVA fibers in proportion;

s102, putting the weighed portland cement, fly ash, kaolin, HPMC (hydroxy propyl methyl cellulose) and fine quartz sand into a stirrer, and performing slow dry stirring for 2 minutes at the rotating speed of the stirrer of 140 +/-5 r/min to obtain a mixture A;

s103, uniformly mixing water and a water reducing agent in proportion, adding the mixture into the mixture A, and slowly stirring for 3 minutes at the rotating speed of a stirrer of 140 +/-5 r/min to obtain a mortar matrix with certain fluidity;

s104, dispersing the PVA fibers, and slowly adding the dispersed PVA fibers along the rotation direction of a blade of a stirrer, wherein the rotation speed of the stirrer is 285 +/-10 r/min;

and S105, stirring for 5-8 minutes in combination with the fiber dispersion condition to obtain the PVA-ECC mixture with well-dispersed fibers.

The technical effects of the present invention will be further described with reference to specific embodiments.

Example 1:

the invention provides a formula of a sprayable PVA-ECC high-ductility cement-based composite material and a preparation method thereof, the formula contains cement, quartz sand, high-activity moderately-aged soil, fly ash, a water reducing agent, HPMC and PVA fiber, the mass ratio of water to a cementing material in the sprayable ECC (error correction code), namely the mass ratio of water to the cementing material, is 0.28-0.3, the mass ratio of sand to glue, namely the mass ratio of fine quartz sand to the cementing material is 1:2, and the cementing material is ordinary portland cement, fly ash and moderately-aged soil. The fly ash accounts for 30-65% of the total amount of the cementing material, the super clay accounts for 5-10% of the total amount of the cementing material, the accelerator containing 3-8% of the amount of the cementing material, the HPMC containing 0.3-0.6% of the amount of the cementing material and the water reducer containing 0.2-1% of the amount of the cementing material are used, the volume fraction of the PVA in the ECC capable of being sprayed is 1.5-2%, and therefore the mass of the PVA capable of being sprayed with the ECC in each vertical direction is 19.5-26 kg.

Firstly, dividing the raw materials into three groups of powder particles, liquid and fibers, wherein the first group is ordinary portland cement, first-grade fly ash, first-grade super-kaolin and fine quartz sand, the second group is a mixture of water and a water reducing agent, and the third group is primarily dispersed PVA fibers;

then putting the first group of powder particles weighed according to the mixing proportion into a stirrer, and slowly and dry-stirring for 2 minutes; adding the second group of liquid into the uniformly stirred mixture, and slowly stirring for 3 minutes to obtain a mortar matrix with certain fluidity;

and finally, slowly adding the PVA fibers in the third group along the rotating direction of the blades of the stirrer, and stirring for 5-8 minutes according to the fiber dispersion condition after the fiber is put into the stirrer. At the moment, the whole preparation process is finished, and the PVA-ECC mixture with well dispersed fibers is obtained.

Example 2

The sprayable PVA-ECC high-ductility cement-based composite material is prepared from 568.1 parts of ordinary portland cement, 568.1 parts of fine quartz sand, 568.1 parts of first-grade fly ash, 340.8 parts of water, 9.1 parts of a water reducing agent, 0.6 part of HPMC and 26 parts of 8mm PVA fiber (in mass).

Firstly, dividing the raw materials into three groups of powder particles, liquid and fibers, wherein the first group is ordinary portland cement, first-grade fly ash, first-grade super-kaolin and fine quartz sand, the second group is a mixture of water and a water reducing agent, and the third group is primarily dispersed PVA fibers; then putting the first group of powder particles weighed according to the mixing proportion into a stirrer, and slowly and dry-stirring for 2 minutes; adding the second group of liquid into the uniformly stirred mixture, and slowly stirring for 3 minutes to obtain a mortar matrix with certain fluidity; and finally, slowly adding the PVA fibers in the third group along the rotating direction of the blades of the stirrer, and stirring for 5-8 minutes according to the fiber dispersion condition after the fiber is put into the stirrer. At the moment, the whole preparation process is finished, and the PVA-ECC mixture with well dispersed fibers is obtained.

And (3) test results: the sprayable ECC material of example 2 has good tensile property, obvious strain hardening phenomenon, stable multi-crack cracking and small crack fineness, wherein the tensile stress-strain curve of a test piece is shown in FIG. 2. The ultimate strain is 4.21 percent, the ultimate tensile strength is 3.52MPa, and the 28d compressive strength reaches 42.7 MPa.

Example 3

The sprayable PVA-ECC high-ductility cement-based composite material is prepared from the following raw materials (in mass) 397.6 parts of ordinary portland cement, 568.1 parts of fine quartz sand, 738.5 parts of first-grade fly ash, 340.8 parts of water, 9.1 parts of a water reducing agent, 0.6 part of HPMC and 26 parts of 8mm PVA fiber.

The procedure is as in example 2.

And (3) test results: the sprayable ECC material of example 3 has good tensile property, obvious strain hardening phenomenon and stable multi-slit cracking, wherein the tensile stress-strain curve of a test piece is shown in FIG. 3. The ultimate strain is 2.8 percent, the ultimate tensile strength is 3.45MPa, and the 28d compressive strength reaches 41.0 MPa.

Example 4

A sprayable PVA-ECC high-ductility cement-based composite material is prepared from (by mass) 454.4 parts of ordinary portland cement, 568.1 parts of fine quartz sand, 568.1 parts of first-grade fly ash, 113.6 parts of high-activity kaolin, 340.8 parts of water, 9.1 parts of a water reducing agent, 0.6 part of HPMC (hydroxy propyl methyl cellulose) and 19.5 parts of PVA fiber PVA (8 mm).

The procedure is as in example 2.

And (3) test results: the sprayable ECC material of example 4 has good tensile property, obvious strain hardening phenomenon, unstable multi-crack cracking and large crack width, wherein the tensile stress-strain curve of the test piece is shown in FIG. 4. The ultimate strain is 3.52 percent, the ultimate tensile strength is 3.17MPa, and the 28d compressive strength reaches 43.6 MPa.

Example 5

A sprayable PVA-ECC high-ductility cement-based composite material is prepared from (by mass) 454.4 parts of ordinary portland cement, 568.1 parts of fine quartz sand, 568.1 parts of first-grade fly ash, 113.6 parts of high-activity kaolin, 340.8 parts of water, 9.1 parts of a water reducing agent, 0.6 part of HPMC and 26 parts of 8mm PVA fiber PVA.

The procedure is as in example 2.

And (3) test results: the sprayable ECC material of example 5 has good tensile property, obvious strain hardening phenomenon, stable multi-crack cracking and small crack width, wherein the tensile stress-strain curve of the test piece is shown in FIG. 5. The ultimate strain is 3.52 percent, the ultimate tensile strength is 3.17MPa, and the 28d compressive strength reaches 43.6 MPa.

Example 6

A sprayable PVA-ECC high-ductility cement-based composite material is prepared from 449.5 parts by mass of ordinary portland cement, 561.8 parts by mass of fine quartz sand, 561.8 parts by mass of first-grade fly ash, 112.4 parts by mass of high-activity kaolin, 359.6 parts by mass of water, 9.0 parts by mass of a water reducing agent, 0.6 part by mass of HPMC and 26 parts by mass of PVA fiber (8 mm).

The procedure is as in example 2.

And (3) test results: the sprayable ECC material of example 6 has good tensile property, obvious strain hardening phenomenon, stable multi-crack cracking and small crack width, wherein the tensile stress-strain curve of the test piece is shown in FIG. 6. The ultimate strain is 4.26 percent, the ultimate tensile strength is 3.31MPa, and the 28d compressive strength reaches 48.8 MPa.

Example 7

A sprayable PVA-ECC high-ductility cement-based composite material is prepared from 459.6 parts of ordinary portland cement, 574.4 parts of fine quartz sand, 574.4 parts of first-grade fly ash, 114.9 parts of high-activity kaolin, 321.7 parts of water, 9.2 parts of a water reducing agent, 0.6 part of HPMC and 26 parts of 8mm PVA fiber PVA by mass.

The procedure is as in example 2.

And (3) test results: the sprayable ECC material of example 7 has good tensile property, obvious strain hardening phenomenon, stable multi-crack cracking and small crack width, wherein the tensile stress-strain curve of the test piece is shown in FIG. 7. The ultimate strain is 4.06 percent, the ultimate tensile strength is 2.82MPa, and the 28d compressive strength reaches 37.7 MPa.

Example 8

A sprayable PVA-ECC high-ductility cement-based composite material is prepared from (by mass) 454.4 parts of ordinary portland cement, 568.1 parts of fine quartz sand, 568.1 parts of first-grade fly ash, 113.6 parts of high-activity kaolin, 340.8 parts of water, 9.1 parts of a water reducing agent, 0.6 part of HPMC and 19.5 parts of PVA fiber PVA with the length of 12 mm.

The procedure is as in example 2.

And (3) test results: the sprayable ECC material of example 8 has good tensile property, obvious strain hardening phenomenon, stable multi-crack cracking and small crack width, wherein the tensile stress-strain curve of the test piece is shown in FIG. 8. The ultimate strain is 4.0 percent, the ultimate tensile strength is 3.32MPa, and the 28d compressive strength reaches 44.1 MPa.

The tensile test piece and the uniaxial compression test piece were prepared according to "mechanical property test method for high-ductility fiber-reinforced cement-based composite material" (JC/T2461-2018) and "standard for basic mechanical property test method for ordinary concrete" (GB50081-2002), and the uniaxial tensile test and the compressive strength test were performed on the sprayable ECC of the above example. The fluidity of the freshly mixed PVA-ECC was tested according to GBT2419-2005 "Cement mortar fluidity determination method".

Table 1 compares the mechanical performance parameters of the sprayable ECC of the examples of the present invention:

the above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.

Claims

1. The sprayable PVA-ECC high-ductility cement-based composite material is characterized by comprising 10 parts of cementing material, 5 parts of fine quartz sand, 0.03-0.06 part of cellulose HPMC, 0.02-0.1 part of water reducing agent, 0.17-0.23 part of PVA fiber and 2.8-3 parts of water in parts by mass;

2. The sprayable PVA-ECC high ductility cement-based composite of claim 1, wherein the cementitious material consists of 25% to 65% portland cement, 30% to 65% fly ash, and 5% to 10% meta-high age soil.

3. The sprayable PVA-ECC high ductility cement-based composite of claim 2, wherein the portland cement is a 42.5 grade portland cement; the apparent density is 3150kg/m3, and the specific surface area is 352m 2/kg; the loss on ignition is not more than 5.0 percent, the initial setting time is 1 hour, and the final setting time is 3 hours.

4. The sprayable PVA-ECC high ductility cement-based composite of claim 2, wherein the fly ash is a class F low calcium fly ash having a free calcium oxide mass content of less than 1%.

5. The sprayable PVA-ECC high ductility cement-based composite material according to claim 2, wherein the higher age soil is a 750 ℃ calcined higher age soil having an activity of 1250 mesh.

6. The sprayable PVA-ECC high ductility cement-based composite material of claim 1, wherein the fine quartz sand has a fineness of 100-200 mesh and a silica content of not less than 99%.

7. The sprayable PVA-ECC high ductility cement-based composite of claim 1, wherein the water reducer is a polycarboxylate water reducer with a water reduction rate of 25%.

8. The sprayable PVA-ECC high ductility cement-based composite of claim 1, wherein the PVA fiber has an ultimate tensile strength of 1550MPa, an elongation of 6.3%, an elastic modulus of 39GPa, a density of 1.3g/cm³The diameter was 39 μm and the length was 8 mm.

9. A method of preparing a sprayable PVA-ECC high ductility cementitious composite according to claims 1 to 8, comprising:

putting the weighed portland cement, fly ash, kaolin, HPMC (hydroxy propyl methyl cellulose) and fine quartz sand into a stirrer, and performing dry mixing to obtain a mixture A;

step three, uniformly mixing water and a water reducing agent in proportion, adding the mixture into the mixture A, and stirring to obtain a mortar matrix with certain fluidity;

dispersing the PVA fiber, slowly adding the dispersed PVA fiber along the rotation direction of a blade of the stirrer, and stirring;

and fifthly, stirring for 5-8 minutes in combination with the fiber dispersion condition to obtain the PVA-ECC mixture with good fiber dispersion.

10. The method for preparing the sprayable PVA-ECC high ductility cement-based composite material according to claim 9, wherein in the second step, the slow dry mixing is carried out for 2 minutes at a mixer rotation speed of 140 +/-5 r/min;

in the third step, the rotating speed of the stirrer is 140 +/-5 r/min, and the stirring is carried out for 3 minutes at a low speed;

the rotating speed of the stirrer in the fourth step is 285 +/-10 r/min.