Polypropylene fiber for cement reinforcement, molded cement made with the fiber, method of constructing concrete structure, and method of spray concreting

a technology of polypropylene fiber and cement reinforcement, which is applied in the direction of fibre treatment, yarn, transportation and packaging, etc., can solve the problems of difficult to carry or be entrapped materials, comparatively fragile molds, and accidents involving peeling or dropping of external walls, etc., to achieve excellent hydrophilicity, improve hydrophilicity, and increase the wetting index

Inactive Publication Date: 2006-04-13
HAGIHARA IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0011] The present invention basically provides fibers for cement reinforcement that have an increased index of wetting on their surface and improved hydrophilicity. The fibers comprise specified polyolefin resin, having undergone a specified surface modification treatment on surfaces thereof. That is, the fibers are spun from polypropylene resin, and their surfaces have undergone a surface modification treatment selected from oxidation treatment and fluorination treatment so that the fiber surfaces have an index of wetting of 38 dyn / cm or higher. Here, the index of wetting is a Japanese industrial standard that indicates ability for holding an adhesion between the fiber surface and the concrete. By this, an excellent hydrophilicity is given to boundary surfaces between polypropylene fibers and the cement, and cement moldings are manufactured so as to be excellent in adhesion to the cement matrixes, flexural strength and impact strength.

Problems solved by technology

However, these moldings have are comparatively fragile.
Therefore, unless properties such as the reinforced strength, flexural proof stress, flexural toughness and impact strength thereof are enough, water leaks and external-wall peeling or dropping accidents happen due to cracks of wall surfaces.
However, as for the concrete in which the steel fibers are entrapped, since the specific gravity of steel fibers is as heavy as 7.8, materials including them are difficult to carry or be entrapped.
In addition, as for shotcrete, when the concrete is sprayed, splashed and dropped, steel fibers are sometimes stepped on, causing workers to be injured.
Moreover, there is another problem as the steel fibers get rusty.
However, this autoclave curing has a problem that fibers other than those of polyolefin resin can not be used for reinforcement because they deteriorate from a shortage of heat resistant alkalinity.
On the other hand, polyolefin resin has few hydrophilic radicals in the molecular structure and few functional groups available for the adhesive property of the cement, and therefor, the adhesion of the cement matrixes is extremely inferior.
Therefore, even if the impact strength and breaking energy due to drawing resistance of the fibers increase, flexural strength has not been improved greatly yet.
However, in this case, since foreign matter is entrapped all over the resin fibers, a drawing property is missing and not enough fiber strength is obtained.
In addition, nothing contributes to improving affinity except a modifier on the surfaces of the resin fibers, and not enough reforming effects can be obtained for the amount added.
In addition, it is difficult to equally disperse the fibers in the cement because they are bulky.
In increasing the fineness of the fibers to improve dispersibility, adhesion to the cement is inferior, and the fibers are drawn out when flexural stress is charged.
Therefore, enough reinforcing effects can not be obtained.
However, since the surfactants have no adhesion to the polyolefine resin fibers, even if the polyolefin resin fibers adhere to the cement matrixes, enough adhesive strength can not be achieved therebetween.
Accordingly, the cement moldings can not improve in flexural toughness.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0055] Polypropylene resin (MFR=1.0 g / 10 minutes) was fed into an extruder, extruded from string-shaped nozzles having 2 mm φ×10 bores at 230° C. resin temperature, and drawn by a hot plate contact type drawing method. A drawing temperature was 130° C., an annealing temperature was 135° C., and a drawing magnification was 12 times. The given drawn yarn had the single yarn fineness of 50 dt.

[0056] The drawn yarn surface had undergone a corona discharge treatment as a surface oxidation treatment under 20 w·minute per 1 m2. The given polypropylene resin drawn yarn surface had an index of wetting of 42 dyn / cm.

[0057] The polypropylene resin drawn yarn was cut in 10 mm length to form short fibers.

[0058] Molding for cement moldings was based on JISR5201. That is, 100 wt. parts Portland cements and 200 wt. parts standard sands were mixed sufficiently, and therein, the fibers of 5 wt. parts and water of 65 wt. parts are added. Then they were mixed uniformly on the whole. Thereafter, they ...

example 2

[0064] The same treatments as Example 1 except the conditions that the polypropylene resin drawn yarn surface had undergone the corona discharge treatment at the rate of 30 w·minute per 1 m2 and the index of wetting the surface was 45 dyn / cm were performed.

[0065] The given moldings had the flexural strength of 26.5 MPa, Charpy impact strength of 9.8 KJ / m2. The dispersibility was good.

example 3

[0066] A drawn yarn was produced similarly with Example 1 and cut in 10 mm length to form short fibers. The short fibers were put into a reaction container, and thereafter, the container was placed under a vacuum. Gaseous oxygen of 80% by volume and gaseous fluorine of 20% by volume were injected in order, and these were reacted at 20° C. under 10 Pa pressure. The given fibers had surfaces having the index of wetting of 60 dyn / cm.

[0067] Cement moldings were molded similarly with Example 1 by using these short fibers. The given moldings had a flexural strength of 28.0 MPa and Charpy impact strength of 10.5 KJ / m2. The dispersibility was good.

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Abstract

Polyolefin resin fibers for cement reinforcement which have hydrophilicity imparted thereto and show excellent adhesion to cement matrices. The fibers are ones which have been formed from a polypropylene resin by spinning and have undergone a surface modification treatment selected from oxidation treatment and fluorination treatment so that the fiber surface has an index of wetting of 38 dyn/cm or higher. The polypropylene resin fibers for cement reinforcement, when used in the application or placing of various mortars or concretes, give cement moldings improved in flexural toughness, such as flexural strength and impact strength.

Description

FIELD OF THE INVENTION [0001] The present invention relates to polypropylene resin fibers for cement reinforcement excellent in adhesive property to cement matrixes and in reinforcing mortars, concrete and the like. In addition, the invention relates to fiber-reinforced molded cement made with the polypropylene resin fibers, a method of constructing concrete structure therewith, and a method of concrete spraying therewith. BACKGROUND OF THE INVENTION [0002] Conventionally, cement moldings, external walls of architectures, inner walls of tunnels and hillside slopes, etc. are constructed with mortars, concrete and the like. However, these moldings have are comparatively fragile. Therefore, unless properties such as the reinforced strength, flexural proof stress, flexural toughness and impact strength thereof are enough, water leaks and external-wall peeling or dropping accidents happen due to cracks of wall surfaces. Therefore, recently, synthetic resin fibers such as steel fibers, po...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D02G3/00C04B16/06C04B28/02D06M11/07E04C5/07
CPCC04B16/0633C04B28/02D06M11/07D06M2200/00Y10T428/2913E04C5/073C04B20/023
Inventor YABUKI, MASUONAKASHIMA, KAZUMASA
Owner HAGIHARA IND INC
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