CN109057395B

CN109057395B - FRP-expansion ECC composite pipe for prestress reinforcement of pressure steel pipe and construction process thereof

Info

Publication number: CN109057395B
Application number: CN201811127451.6A
Authority: CN
Inventors: 黄辉; 贾彬; 路四方; 周浩
Original assignee: Southwest University of Science and Technology
Current assignee: Southwest University of Science and Technology
Priority date: 2018-09-27
Filing date: 2018-09-27
Publication date: 2023-04-28
Anticipated expiration: 2038-09-27
Also published as: CN109057395A

Abstract

The invention discloses an FRP-expansion ECC composite pipe for prestress reinforcement of a pressure steel pipe and a construction process thereof, wherein the FRP-expansion ECC composite pipe is arranged on the outer surface of a defective steel pipe and comprises the following components: an expansion ECC layer wrapping the outer surface of the defective steel pipe; a fiber cloth layer wrapped on the outer surface of the expanded ECC layer; the steel rings I with conical outer surfaces are respectively sleeved at two ends of the defective steel pipe and positioned between the fiber cloth layer and the defective steel pipe; the inner surface of the end part of the fiber cloth layer is sleeved on the steel ring I; the steel ring II is sleeved on the outer surface of the end part of the fiber cloth layer and corresponds to the steel ring I in position, so that the fiber cloth layer is fixed between the steel ring I and the steel ring II; the upper end of the steel ring I positioned at one end of the defective steel pipe is provided with an axial upper reserved hole, and the lower end of the steel ring I positioned at the other end of the defective steel pipe is provided with an axial lower reserved hole. The invention solves the problems that the defect steel pipe is corroded in the use process and repair and reinforcement are needed in the practical application.

Description

FRP-expansion ECC composite pipe for prestress reinforcement of pressure steel pipe and construction process thereof

Technical Field

The invention belongs to the field of civil engineering FRP fiber cloth, and particularly relates to an FRP-expansion ECC composite pipe for prestress reinforcement of a pressure steel pipe and a construction process thereof.

Background

Fiber reinforced composites (FRP) have the advantages of high tensile strength, light weight, corrosion resistance, thermal expansion coefficient close to that of concrete, and the like, have been widely accepted and applied in the civil engineering field since the advent of the world, and are becoming research hot spots in the field. The fiber cloth has high strength, small density and thin thickness, the dead weight and the section size of the reinforcing member are not increased basically, the carbon fiber cloth is used for the tensile, shearing and shock resistance reinforcement of the structural member, and the material and the matched impregnating adhesive are used together to form a carbon fiber composite material, so that a complete carbon fiber cloth sheet reinforcing system with excellent performance can be formed. The air contains water and air, carbon dioxide and iron can generate chemical reaction, and the common iron contains carbon, carbon element and iron form countless primary cells on the surface of the iron in the solution of the water and the carbon dioxide in the air, so that the corrosion of the steel pipe is accelerated, and if the steel pipe is buried underground, the chemical element in the soil can accelerate the corrosion of the steel pipe, so that the steel pipe inevitably encounters the problem that the corrosion needs to be reinforced in use. Traditional repairing methods for steel pipes are as follows: the normal use of the pipeline is greatly affected by welding and replacement. Therefore, there is a bottleneck in the steel pipe when reinforcement is required due to corrosion, and a device for repairing the reinforced steel pipe is required to further exert the value of the steel pipe. The development of a safe, economical and practical repairing and reinforcing system is a precondition for researching reinforcing and repairing of the steel pipe, and is one of keys for bringing the steel pipe reinforcing and prestress anchorage to the market and applying the steel pipe reinforcing and prestress anchorage to an actual structure.

Disclosure of Invention

It is an object of the present invention to address at least the above problems and/or disadvantages and to provide at least the advantages described below.

To achieve these objects and other advantages and in accordance with the purpose of the invention, there is provided an FRP-expanded ECC composite pipe for prestress reinforcement of a penstock, which is provided at an outer surface of a defective penstock, comprising:

an expansion ECC layer wrapping the outer surface of the defective steel pipe;

a fiber cloth layer wrapped on the outer surface of the expanded ECC layer;

the steel rings I with conical outer surfaces are respectively sleeved at two ends of the defective steel pipe and positioned between the fiber cloth layer and the defective steel pipe; the inner surface of the end part of the fiber cloth layer is sleeved on the steel ring I;

the steel ring II is sleeved on the outer surface of the end part of the fiber cloth layer and corresponds to the steel ring I in position, so that the fiber cloth layer is fixed between the steel ring I and the steel ring II;

the upper end of the steel ring I positioned at one end of the defective steel pipe is provided with an axial upper reserved hole, and the lower end of the steel ring I positioned at the other end of the defective steel pipe is provided with an axial lower reserved hole.

Preferably, the fiber cloth layer is any one of a bidirectional carbon fiber cloth layer, an aramid fiber cloth layer, a high-strength glass fiber cloth layer and a basalt fiber cloth layer.

Preferably, the fiber cloth layer is a multi-layer fiber cloth, and the multi-layer fiber cloth is formed by winding the fiber cloth for a plurality of times; and epoxy resin glue is coated between the fiber cloth layers of the multi-layer fiber cloth, and the fiber cloth is completely soaked.

Preferably, the thickness of the bidirectional carbon fiber cloth is 0.12-0.15 mm.

Preferably, the steel ring I is formed by connecting two semicircular steel rings I with semi-conical outer surfaces through a clamp; the steel ring II is formed by connecting two semicircular steel rings II through a clamp.

Preferably, the end of the conical surface of the steel ring I with the conical outer surface is provided with a plurality of axial branch pipes.

The invention also provides a construction process of the FRP-expansion ECC composite pipe for prestress reinforcement of the pressure steel pipe, which comprises the following steps:

polishing the surface of a defective steel pipe to be smooth, wiping the surface with alcohol, and then adhering polystyrene foam to the surface of the defective steel pipe with special glue for pearl wool;

winding fiber cloth on the surface of the polystyrene foam after the polystyrene foam is fixed, smearing epoxy resin in the winding process, fully soaking the fiber cloth, and then curing;

step three, forming a fiber cloth layer after the fiber cloth and the epoxy resin are solidified; then using a mixed solvent of n-butyl acetate and dimethylbenzene with the volume ratio of 1:2 to dissolve polystyrene foam between the fiber cloth layer and the surface of the defective steel pipe, and cleaning;

sleeving a steel ring I with a conical outer surface between the fiber cloth layer and the defective steel pipe, enabling the conical outer surfaces of the steel rings I at two ends to be oppositely arranged, arranging an upper reserved hole at the top part and arranging a lower reserved hole at the bottom part;

sleeving a steel ring II on the outer surface of the end part of the fiber cloth layer and corresponding to the steel ring I in position so as to fix the fiber cloth layer between the steel ring I and the steel ring II;

and step six, injecting the expansion ECC from the lower reserved hole, stopping injecting until the expansion ECC overflows from the upper reserved hole, blocking the lower reserved hole and the upper reserved hole, curing to form an expansion ECC layer, and obtaining the FRP-expansion ECC composite pipe for prestress reinforcement of the pressure steel pipe.

Preferably, in the third step, the preparation method of n-butyl acetate comprises the following steps: adding concentrated sulfuric acid, glacial acetic acid and n-butanol with the volume ratio of 1:2:3 into a dry container, uniformly mixing, adding zeolite, installing a water separator at the container mouth, loading a reflux condenser pipe on the water separator, adding a certain amount of water into the water separator in advance, heating and refluxing the container on asbestos screen, gradually removing water after reacting for a certain time, keeping the water level of the water layer in the water separator at the original height, waiting for a period of time without water generation, stopping heating and cooling, removing the shunt pipe, pouring the lipid layer separated from the water separator and the reaction solution in the flask into a separating funnel together, washing the lipid layer with 10% sodium carbonate solution until the pH value is 7, separating the water layer, washing the lipid layer once again, separating the water layer, pouring the lipid layer into a conical flask, adding a small amount of anhydrous sodium sulfate, pouring the dried lipid layer into the container, adding zeolite, heating and distilling on the asbestos screen, and collecting the fraction at 115-126 ℃, namely n-butyl acetate.

Preferably, the preparation method of the expansion ECC comprises the following steps: adding 300-500 parts of water, 320-450 parts of cement, 350-550 parts of quartz sand, 800-950 parts of fly ash, 10-20 parts of water reducer, 45-65 parts of silica fume, 35-55 parts of quicklime and 30-40 parts of rubber powder into a mixing tank for stirring and mixing, and spraying 120-150 parts of polymer solution with the concentration of 5-12% into the mixing tank in the form of nano fibers by an electrostatic spinning method while stirring and mixing to obtain an expansion ECC (error correction code); the electrostatic spinning method comprises the following steps: adding polyvinyl alcohol, polyvinylpyrrolidone and 1-ethyl-3-methylimidazole lactic acid in a weight ratio of 2:1:0.2 into water to prepare a polymer solution with a mass concentration of 5-12%, injecting the polymer solution into an injection container with a stainless steel nozzle of an electrostatic spinning device, applying voltage to the stainless steel nozzle by using a high-voltage power supply, injecting the polymer solution in the injection container through the stainless steel nozzle by using a propulsion pump connected with the injection container, and injecting the polymer solution into a mixing tank in a nanofiber form; the spraying conditions adopted by the electronic spraying method are as follows: the environment temperature is 20-40 ℃, the distance between the mixing tank and the stainless steel spray nozzle is 5-10 cm, the spraying flow of the polymer solution is 10-20 mL/min, the voltage is 12-28 kV, and the inner diameter of the stainless steel spray nozzle is 0.8-1.6 mm.

The invention at least comprises the following beneficial effects:

the invention solves the problems that the steel pipe is defective due to corrosion in the use process and needs to be repaired and reinforced in the practical application. When the prestress anchor is produced in a large scale, the plasticity of the steel ring I with the conical outer surface is good, the requirement on materials is low, and the prestress anchor can be produced according to actual requirements. The FRP-expansion ECC composite pipe has the advantages of simple structure, reasonable design and convenient implementation, and can be widely applied to engineering; the FRP-expansion ECC composite pipe disclosed by the invention is adhesive tape and acts simultaneously, glue is filled between the fiber cloth and the steel pipe, the fiber cloth and the steel pipe are bonded, and an annular anchorage device is used for anchoring outside the sleeve, so that the bonding of the fiber cloth and the steel pipe is firmer, the reinforcing and repairing of the steel pipe are more beneficial, the prepared expansion ECC and adhesive glue have excellent performances, and the ultimate strength of the FRP-expansion ECC composite pipe can be obviously improved.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Description of the drawings:

FIG. 1 is a longitudinal cross-sectional view of an FRP-expanded ECC composite pipe of the present invention;

FIG. 2 is a top view of the FRP-expanded ECC composite pipe of the present invention;

FIG. 3 is a cross-sectional view A-A of FIG. 1;

FIG. 4 is a left side view of steel ring I with a tapered outer surface at the left end of FIG. 1;

FIG. 5 is a right side view of steel ring I with a tapered outer surface at the right end of FIG. 1;

fig. 6 is a detail view of the left end of fig. 1;

FIG. 7 is a left side view of FIG. 1;

FIG. 8 is a right side view of FIG. 1;

FIG. 9 is a detail view of the right end of FIG. 1;

FIG. 10 is a front view of steel rim I having a tapered outer surface;

FIG. 11 is a front view of rim II;

FIG. 12 is a longitudinal cross-sectional view of an FRP-expanded ECC composite pipe of another structure of the present invention;

fig. 13 is a front view of a steel ring i having a tapered outer surface of another construction of the present invention.

The specific embodiment is as follows:

the present invention is described in further detail below with reference to the drawings to enable those skilled in the art to practice the invention by referring to the description.

It will be understood that terms, such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

Fig. 1 to 11 show an FRP-expanded ECC composite pipe for prestress reinforcement of penstock according to the present invention, which is provided on the outer surface of a defective steel pipe 1, comprising:

an expansion ECC layer 6 wrapping the outer surface of the defective steel pipe 1;

a fiber cloth layer 2 wrapped on the outer surface of the expanded ECC layer 6;

the steel rings I7 with conical outer surfaces 71 are respectively sleeved at two ends of the defective steel pipe 1 and positioned between the fiber cloth layer 2 and the defective steel pipe 8; the inner surface of the end part of the fiber cloth layer 2 is sleeved on the steel ring I7; the steel ring I is cushioned below the fiber cloth layer to play a role in fixing the composite pipeline of the fiber cloth layer; the steel ring I with the conical outer surface is adopted, so that when the steel ring I is cushioned below the fiber cloth layer composite pipeline, the conical interface is beneficial to the insertion of the steel ring I, and the fiber cloth layer composite pipeline and the steel ring I can be bonded more closely;

the steel ring II 4 is sleeved on the outer surface of the end part of the fiber cloth layer 2 and corresponds to the steel ring I7 in position, so that the fiber cloth layer 2 is fixed between the steel ring I7 and the steel ring II 4;

wherein, the upper end of steel ring I7 that is located defect steel pipe 1 one end is provided with axial upper portion preformed hole 3, and the lower extreme of steel ring I7 that is located defect steel pipe 1 other end is provided with axial lower part preformed hole 5.

In the technical scheme, the fiber cloth layer is fixed through the steel ring I and the steel ring II with the conical outer surfaces, the fiber cloth layer and the defect steel pipe are firmer, the reinforcement of the defect steel pipe is more beneficial, the expansion ECC layer plays a role in regenerating and expanding between the fiber cloth layer and the defect steel pipe, stress is applied to the fiber cloth layer, inward pressure is generated on the defect steel pipe, and the ultimate strength of the FRP-expansion ECC composite pipe is improved; the fiber cloth layer is stuck, so that the effect of protecting steel and preventing corrosion can be achieved; further improving the application of the FRP fiber cloth in engineering.

In the above technical scheme, the fiber cloth layer is any one of a bidirectional carbon fiber cloth layer, an aramid fiber cloth layer, a high-strength glass fiber cloth layer and a basalt fiber cloth layer.

In the technical scheme, the fiber cloth layer is a plurality of layers of fiber cloth, and the plurality of layers of fiber cloth are formed by winding the fiber cloth for a plurality of times; the multi-layer fiber cloth is 0 degrees and 45 degrees along the length direction of the fiber cloth according to the fiber filaments; and epoxy resin glue is coated between the fiber cloth layers of the multi-layer fiber cloth, and the fiber cloth is completely soaked. By adopting the mode, the structure of the multi-layer fiber cloth can better play a role in protecting the steel pipe and preventing corrosion, and the ultimate strength of the FRP-expansion ECC composite pipe can be improved.

In the technical scheme, the thickness of the bidirectional carbon fiber cloth is 0.12-0.15 mm.

In the technical scheme, the steel ring I7 is formed by connecting two semicircular steel rings I72 with semi-conical outer surfaces through a clamp; the steel ring II 4 is formed by connecting two semicircular steel rings II 41 through a clamp, in this way, the fastening and the disassembly of the steel ring I7 and the steel ring II 4 can be realized through the clamp connection mode, and then the formed FRP-expansion ECC composite pipe is firmly fixed and conveniently disassembled.

In the above technical scheme, as shown in fig. 12 to 13, the end of the conical surface of the steel ring i 7 with the conical outer surface is provided with a plurality of axial branch pipes 73, in this way, the plurality of branch pipes can be densely filled by the expansion ECC in the construction process, and can be firmly and fixedly connected with the expansion ECC, so that the ultimate strength of the FRP-expansion ECC composite pipe is further improved.

Example 1:

the construction process of the FRP-expansion ECC composite pipe for prestress reinforcement of the pressure steel pipe comprises the following steps of:

step six, injecting the expansion ECC from the lower reserved hole, stopping injecting until the expansion ECC overflows from the upper reserved hole, blocking the lower reserved hole and the upper reserved hole, curing to form an expansion ECC layer, and obtaining the FRP-expansion ECC composite pipe for prestress reinforcement of the pressure steel pipe;

in the third step, the preparation method of the n-butyl acetate comprises the following steps: adding concentrated sulfuric acid, glacial acetic acid and n-butanol in a volume ratio of 1:2:3 into a dry container, uniformly mixing, adding zeolite, installing a water separator at a container mouth, loading a reflux condenser pipe on the water separator, adding a certain amount of water into the water separator in advance, heating and refluxing the container on an asbestos screen, gradually removing water after reacting for a certain time, keeping the water level of the water layer in the water separator at the original height, waiting for a period of time, removing the shunt pipe after stopping heating and cooling, pouring the lipid layer separated from the water separator and the reaction solution in a flask into a separating funnel together, washing the lipid layer with 10% sodium carbonate solution until the pH value is 7, separating a water layer, washing the lipid layer once again with water, separating the water layer, pouring the lipid layer into a conical flask, adding a small amount of anhydrous sodium sulfate, pouring the dried lipid layer into the container, adding zeolite, heating and distilling on the asbestos screen, and collecting fractions at 115-126 ℃, namely n-butyl acetate;

the preparation method of the expansion ECC comprises the following steps: adding 500 parts of water, 320 parts of cement, 350 parts of quartz sand, 950 parts of fly ash, 20 parts of a water reducing agent, 65 parts of silica fume and 55 parts of quicklime into a mixing tank, stirring and mixing the materials, and spraying 150 parts of polymer solution with the concentration of 8% into the mixing tank in the form of nanofibers through an electrostatic spinning method while stirring and mixing to obtain expansion ECC; the electrostatic spinning method comprises the following steps: adding polyvinyl alcohol, polyvinylpyrrolidone and 1-ethyl-3-methylimidazole lactic acid in a weight ratio of 2:1:0.2 into water to prepare a polymer solution with a mass concentration of 8%, injecting the polymer solution into an injection container with a stainless steel nozzle of an electrostatic spinning device, applying voltage on the stainless steel nozzle by a high-voltage power supply, injecting the polymer solution in the injection container through the stainless steel nozzle by a propulsion pump connected with the injection container, and injecting the polymer solution into a mixing tank in a nanofiber form; the spraying conditions adopted by the electronic spraying method are as follows: the ambient temperature was 40 ℃, the distance between the mixing tank and the stainless steel spray head was 10cm, the polymer solution spray flow was 20mL/min, the voltage was 28kV, and the inner diameter of the stainless steel spray head was 1.6mm.

Example 2:

the preparation method of the expansion ECC comprises the following steps: 400 parts of water, 400 parts of cement, 500 parts of quartz sand, 800 parts of fly ash, 20 parts of a water reducing agent, 45 parts of silica fume and 55 parts of quicklime are added into a mixing tank to be mixed by stirring, and 150 parts of 10% polymer solution is sprayed into the mixing tank in the form of nanofibers by an electrostatic spinning method while stirring and mixing to obtain expansion ECC; the electrostatic spinning method comprises the following steps: adding polyvinyl alcohol, polyvinylpyrrolidone and 1-ethyl-3-methylimidazole lactic acid in a weight ratio of 2:1:0.2 into water to prepare a polymer solution with a mass concentration of 10%, injecting the polymer solution into an injection container with a stainless steel nozzle of an electrostatic spinning device, applying voltage on the stainless steel nozzle by a high-voltage power supply, injecting the polymer solution in the injection container through the stainless steel nozzle by a propulsion pump connected with the injection container, and injecting the polymer solution into a mixing tank in a nanofiber form; the spraying conditions adopted by the electronic spraying method are as follows: the environment temperature is 40 ℃, the distance between the mixing tank and the stainless steel spray head is 5cm, the spraying flow of the polymer solution is 15mL/min, the voltage is 20kV, the inner diameter of the stainless steel spray head is 1.2mm, and the polymer nanofiber prepared by the method can be fully fused with other raw materials, and the ultimate strength of the FRP-expansion ECC composite pipe can be further improved.

The expanded ECC layer prepared in example 1 of the present invention was cast, and the obtained expanded ECC layer was subjected to performance test, and its compressive strength was 155MPa, flexural strength was 40MPa, and tensile strength was 28.5MPa.

The expanded ECC layer prepared in example 2 of the present invention was cast, and the obtained expanded ECC layer was subjected to performance test, and had a compressive strength of 157MPa, a flexural strength of 42MPa, and a tensile strength of 29.5MPa.

Comparative example 1:

the preparation method of the expansion ECC comprises the following steps: 400 parts of water, 400 parts of cement, 500 parts of quartz sand, 800 parts of fly ash, 20 parts of water reducer, 45 parts of silica fume, 55 parts of quicklime, 40 parts of rubber powder and 15 parts of polymer fiber are added into a mixing tank to be stirred and mixed to obtain expansion ECC; the polymer fiber is formed by mixing polyvinyl alcohol fiber, polyvinylpyrrolidone fiber and 1-ethyl-3-methylimidazole lactic acid in a weight ratio of 2:1:0.2;

the rest of the procedure was exactly the same as in example 2;

the expanded ECC layer prepared in comparative example 1 was cast, and the resulting expanded ECC layer was subjected to performance test, with a compressive strength of 121MPa, a flexural strength of 28MPa, and a tensile strength of 17.5MPa.

Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well suited to various fields of use for which the invention would be readily apparent to those skilled in the art, and accordingly, the invention is not limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.

Claims

1. An FRP-expanded ECC composite pipe for prestress reinforcement of a penstock, which is provided on an outer surface of a defective penstock, comprising:

an expansion ECC layer wrapping the outer surface of the defective steel pipe;

a fiber cloth layer wrapped on the outer surface of the expanded ECC layer;

the upper end of the steel ring I positioned at one end of the defective steel pipe is provided with an axial upper preformed hole, and the lower end of the steel ring I positioned at the other end of the defective steel pipe is provided with an axial lower preformed hole;

2. The FRP-expanded ECC composite pipe for prestressed reinforcement of a penstock according to claim 1, wherein the fiber cloth layer is any one of a bi-directional carbon fiber cloth layer, an aramid fiber cloth layer, a high-strength glass fiber cloth layer, and a basalt fiber cloth layer.

3. The FRP-expanded ECC composite pipe for prestress reinforcement of penstock according to claim 1, wherein the fiber cloth layer is a multi-layered fiber cloth formed by winding a fiber cloth a plurality of times; and epoxy resin glue is coated between the fiber cloth layers of the multi-layer fiber cloth, and the fiber cloth is completely soaked.

4. The FRP-expanded ECC composite pipe for prestressed reinforcement of a penstock according to claim 2, wherein the thickness of the bidirectional carbon fiber cloth is 0.12-0.15 mm.

5. The FRP-expanded ECC composite pipe for prestress reinforcement of penstock according to claim 1, wherein the steel ring i is composed of two semicircular steel rings i having semi-conical outer surfaces connected by a clip; the steel ring II is formed by connecting two semicircular steel rings II through a clamp.

6. The FRP-expanded ECC composite pipe for prestress reinforcement of penstock according to claim 1, wherein an end of the tapered surface of the steel ring i having a tapered outer surface is provided with a plurality of branch pipes in an axial direction.

7. The FRP-expanded ECC composite pipe for prestressed reinforcement of penstock according to claim 1, wherein in said step three, n-butyl acetate is prepared by the following method: adding concentrated sulfuric acid, glacial acetic acid and n-butanol with the volume ratio of 1:2:3 into a dry container, uniformly mixing, adding zeolite, installing a water separator at the container mouth, loading a reflux condenser pipe on the water separator, adding a certain amount of water into the water separator in advance, heating and refluxing the container on asbestos screen, gradually removing water after reacting for a certain time, keeping the water level of the water layer in the water separator at the original height, waiting for a period of time without water generation, stopping heating and cooling, removing the shunt pipe, pouring the lipid layer separated from the water separator and the reaction solution in the flask into a separating funnel together, washing the lipid layer with 10% sodium carbonate solution until the pH value is 7, separating the water layer, washing the lipid layer once again, separating the water layer, pouring the lipid layer into a conical flask, adding a small amount of anhydrous sodium sulfate, pouring the dried lipid layer into the container, adding zeolite, heating and distilling on the asbestos screen, and collecting fractions at 115-126 ℃, namely n-butyl acetate.

8. The FRP-expanded ECC composite pipe for prestressed reinforcement of penstock according to claim 1, wherein the preparation method of the expanded ECC is: adding 300-500 parts of water, 320-450 parts of cement, 350-550 parts of quartz sand, 800-950 parts of fly ash, 10-20 parts of water reducer, 45-65 parts of silica fume, 35-55 parts of quicklime and 30-40 parts of rubber powder into a mixing tank, stirring and mixing, and spraying 120-150 parts of polymer solution with the concentration of 5-12% into the mixing tank in the form of nano fibers by an electrostatic spinning method while stirring and mixing to obtain an expansion ECC; the electrostatic spinning method comprises the following steps: adding polyvinyl alcohol, polyvinylpyrrolidone and 1-ethyl-3-methylimidazole lactic acid in a weight ratio of 2:1:0.2 into water to prepare a polymer solution with a mass concentration of 5-12%, injecting the polymer solution into an injection container with a stainless steel nozzle of an electrostatic spinning device, applying voltage to the stainless steel nozzle by using a high-voltage power supply, injecting the polymer solution in the injection container through the stainless steel nozzle by using a propulsion pump connected with the injection container, and injecting the polymer solution into a mixing tank in a nanofiber form; the spraying conditions adopted by the electronic spraying method are as follows: the environment temperature is 20-40 ℃, the distance between the mixing tank and the stainless steel spray head is 5-10 cm, the spraying flow of the polymer solution is 10-20 mL/min, the voltage is 12-28 kV, and the inner diameter of the stainless steel spray head is 0.8-1.6 mm.