JP3351724B2 - Polypropylene fiber for cement reinforcement and construction method of shotcrete using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene fiber having an excellent reinforcing effect on concrete and mortar, and a method for constructing shotcrete such as lining of a tunnel or slope concrete using the fiber.

[0002]

2. Description of the Related Art Conventionally, cement moldings using mortar or concrete, or outer walls of buildings, inner walls of tunnels, slopes, and the like have been constructed, but these are relatively brittle as molded bodies. If physical properties such as tensile strength, flexural strength, flexural toughness, and impact resistance are not sufficient, there is a risk that water leakage due to cracks in the wall surface or an accidental separation and fall of the outer wall may occur. Then, for the purpose of reinforcing concrete, steel fibers or polyvinyl alcohol fibers (for example,
No. 3-303837, Japanese Patent Publication No. 1-40786, and Japanese Patent Application Laid-Open No. 8-218220) are widely used. When bending strength and toughness are required for shotcrete, reinforcing wire mesh is installed.

[0003] However, concrete containing steel fibers is difficult to transport and mix materials due to (1) the specific gravity of the steel fibers being as high as 7.8, and (2) rebound during shotcreting. It is pointed out that there is a high risk of injury due to stepping on the dropped steel fiber, and (3) the steel fiber rusts. Concrete mixed with polyvinyl alcohol fiber has the following characteristics: (1) the fiber itself has water absorbency, (2) the fiber is hydrolyzed when heated to a high temperature with alkali, and (3) the slump does not mix with the fiber. And the unit water volume needs to be increased to secure the slump required for spraying.
(4) In order to keep the water: cement ratio constant, it is necessary to increase the amount of cement at a ratio in which the unit water amount is increased. Further, the method of installing the reinforcing wire mesh has problems such that the number of work steps for installing the wire mesh increases, the time for transporting and mounting the material increases, and the cycle of the process is affected.

In order to solve such a problem, in recent years,
Attempts have been made to use polyolefin fibers instead of steel fibers or polyvinyl alcohol fibers because of their good moldability, light weight and low cost. For example, JP-B-58-18343, JP-B-61-301, JP-B-61-26510, JP-B-62-4346,
It is found in JP-B-62-28106, JP-A-9-86984 and the like.

[0005] As the polyolefin-based fibers, single fibers, bundled yarns or short fibers of split yarns having a fineness of generally 0.01 to 100 dr and a fiber length of approximately 0.5 to 5 mm are often used. As a property from this fiber shape, a fiber having a low fineness and shortness has a drawback that a fiber mass called a fiber ball is generated, and the fiber becomes bulky and is difficult to be uniformly dispersed in cement. When the thickness is large, there is a tendency that the adhesiveness to the cement is poor and the fiber is pulled out when a bending stress is applied, so that a sufficient reinforcing effect cannot be obtained. In addition, long fibers having a low fineness are difficult to disperse in cement due to entanglement between fibers, and are often bent and kneaded into cement to cause uneven strength in cement products.

Further, since the polyolefin fiber is hydrophobic, a phenomenon that the fiber floats in a cement slurry occurs. However, by imparting hydrophilicity to the polyolefin fiber, good sedimentation can be obtained, and more dispersibility can be obtained. It is known that a predetermined fiber reinforcing effect can be obtained by improving the fiber quality and homogeneously mixing the fiber and the cement. In addition, in order to improve the entanglement and bunching properties of the polyolefin-based fibers, surface treatment with various surfactants is also performed.

[0007] Such a polyolefin fiber for cement reinforcement is used for obtaining a cement molded product by heating and curing with high production efficiency by being mixed with cement. Cured at a temperature of 200 ° C for about 8 to 20 hours. Polyolefin fibers having a melting point close to that of this heating temperature may cause thermal degradation during the curing period. In particular, fibers with low fineness are affected by heat. However, there was a problem that the fiber function was remarkably reduced.

On the other hand, polyolefin fibers have a specific gravity of 0.1
The weight is low when mixing the same volume of fiber with cement because it is light at about 91, but it is relatively difficult to uniformly disperse it in concrete due to its light specific gravity and hydrophobicity. It is said that it is necessary to consider a mixing method such as a mixing order of water and fiber and a mixing time.

[0009] A concrete mixture containing a polyolefin fiber has a relatively small rebound when sprayed and is good, but the dispersibility of the fiber affects the slump. Becomes difficult,
Conversely, when the slump is large, the rebound tends to be large.

[0010]

SUMMARY OF THE INVENTION A first object of the present invention is to use a lightweight, specific-shaped polypropylene fiber, perform an appropriate pretreatment as necessary, and to disperse the cement into the cement or to disperse the cement into the cement. An object of the present invention is to provide a cement-reinforced polypropylene fiber which has good physical bonding, is excellent in tensile strength, bending strength, bending toughness, impact resistance, and enables a cement molded product in which cracks hardly occur. The second object of the present invention is to reduce the weight,
An object of the present invention is to provide a method of applying shotcrete which is inexpensive and has an excellent reinforcing effect. This shotcrete includes shotcrete.

[0011]

According to a first aspect of the present invention, there is provided a single yarn fineness of 200 which is spun from a polypropylene resin and has irregularities on the surface in a range of 2/1 to 7/1 in average fiber cross section.
Polyoxya for monofilament of ~ 10,000dr
Lualkylene alkyl phenyl ether phosphate
(A) and polyoxyalkylene fatty acid ester (B)
Fiber treatment with a weight ratio of (A) / (B) of 60/40 to 40/60
Agent is attached at 0.01 to 2% by weight based on the total fiber, and the fiber length is 5
A summary is a polypropylene fiber for cement reinforcement obtained by cutting into ~ 60 mm.

In a second aspect of the present invention, 1 m ^{3 of a} concrete mixture comprising cement, fine aggregate, coarse aggregate, water and the like is spun from a polypropylene resin, and the average flatness of the fiber cross section on the surface is 2/1. to 7/1 of the irregularities in the range with respect to monofilament fineness 200~10,000dr was shaped, polio
Xyalkylene alkyl phenyl ether phosphate
(A) and polyoxyalkylene fatty acid ester (B)
And a fiber treatment having a weight ratio of (A) / (B) of 60/40 to 40/60.
Spraying using polypropylene fiber for cement reinforcement characterized by adhering 0.01 to 2% by weight of a physical agent to the total fiber and mixing 4.5 to 18.5 kg of fiber cut to a fiber length of 5 to 60 mm. The concrete construction method shall be the gist.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The polypropylene resin used as a fiber raw material in the present invention is a polypropylene copolymer such as a propylene homopolymer, an ethylene-propylene block copolymer or a random copolymer, or a mixture thereof. can do. Among them, propylene homopolymer is desirable for cement reinforcement requiring high strength and heat resistance, and it is particularly desirable to select one having an isotactic pentad ratio of 0.95 or more.
The melt flow rate of the polypropylene resin (hereinafter, abbreviated as MFR) is 0.1 to 0.1 in terms of continuous stable productivity.
It is preferable to select from the range of 30 g / 10 min., More preferably from the range of 1 to 10 g / 10 min.

In the spinning process, other polyolefins may be added to the polypropylene resin as needed. As other polyolefins here, high-density polyethylene, linear low-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-
And polyethylene-based resins such as alkyl acrylate copolymers and polybutene-1. Further, various additives such as an antioxidant, a lubricant, an ultraviolet absorber, an antistatic agent, an inorganic filler, an organic filler, a pigment, a crosslinking agent, a foaming agent, and a nucleating agent may be blended.

The polypropylene fiber to be spun in the present invention has a main fiber shape of a short fiber obtained by cutting a relatively thick monofilament, and its production method is not particularly limited. A manufacturing technique for extruding a filament from a die having an irregular shape or other continuous yarn shape can be employed.

In addition to the basic monolayer filament, a composite monofilament having a polypropylene high melting point component as a core layer and a polypropylene low melting point component as a sheath layer may be used as the monofilament. In this production method, polypropylene of each layer is melt-kneaded by an extruder, and a core layer composed of a high melting point component is supplied from a central discharge hole of a die in which two layers of discharge holes are provided substantially concentrically. A composite monofilament is obtained by extruding and covering a sheath layer composed of a melting point component. In this case, since the substantial strength depends on the physical properties of the core layer, it is preferable to use propylene homopolymer, isotactic polypropylene, or the like as the high melting point component, while using the propylene-ethylene block copolymer as the low melting point component. Preferred are polymers, random copolymers, syndiotactic polypropylene and the like. By using the composite monofilament obtained in this way, it is possible to suppress the thermal deterioration of the polypropylene fiber during the heat curing during concrete molding.

Next, the monofilament is subjected to a heat drawing and a heat relaxation treatment, and the heat treatment increases the rigidity of the filament to obtain a polypropylene monofilament having a small elongation and suitable for reinforcing cement. This hot stretching is performed at a temperature equal to or lower than the melting point of the polypropylene and equal to or higher than the softening point. Usually, the stretching temperature is 90 to 150 ° C., and the stretching ratio is usually 5.
1212 times, preferably 7 to 9 times. As the hot stretching method, a method such as a hot roll method, a hot plate method, an infrared irradiation method, a hot air oven method, or a hot water method can be employed.

It is important that the single-filament fineness of the formed polypropylene monofilament is from 200 to 10,000 dr, more preferably from 2,000 to 6,500 dr. Single yarn fineness
If it is less than 200dr, the fibers are too thin and the dispersion in the concrete admixture becomes uneven and fiber balls are liable to be formed, which is problematic in terms of workability and reinforceability. The contact area with the object is reduced, and the material is easily pulled out with respect to bending stress.

The tensile strength of the polypropylene filament is preferably at least 5 g / dr, more preferably at least 6 g / dr. Further, the tensile elongation is preferably 20% or less, more preferably 15% or less. If the tensile strength and the tensile elongation are out of these ranges, the strength as a polypropylene fiber for cement reinforcement is insufficient, which is not preferable.

As for the polypropylene monofilament, it is necessary to form irregularities on the surface as a next step of spinning and heat drawing. As a result, the contact area between the fiber and the concrete can be increased, and the fiber can be prevented from being pulled out after the concrete has hardened, thereby enhancing the reinforcing effect. As a method of shaping the surface, there is a method of embossing a monofilament. The embossing is performed by passing the monofilament through an embossing roll before or after the stretching, so that irregularities are continuously formed in the longitudinal direction of the monofilament.

Here, the shape such as the length and depth of the emboss may be arbitrary, but it is necessary that the average flatness of the fiber cross section by crushing is in the range of 2/1 to 7/1. . The average flatness is a numerical value indicating an average ratio of width and height in the cross section of the formed fiber having various shapes. When the average flatness is less than 2/1, the unevenness of the fiber surface is reduced. Due to the small shape, there is no difference between the smooth surface fiber and the reinforcing effect. On the other hand, if the average flatness exceeds 7/1, the strength is significantly deteriorated due to shaping, and the fiber of the predetermined fineness is dispersed in concrete. This tends to worsen the performance, which is a problem.

Further, the polypropylene monofilament having a surface with irregularities may be subjected to various treatments before or after cutting into short fibers described later.
For example, the fiber surface may be treated with a surfactant, a dispersant, a coupling agent, or the like, or may be subjected to a treatment such as surface activation or cross-linking by corona discharge treatment, ultraviolet irradiation, electron beam irradiation, or the like. Good.

Here, it is effective to perform a surface treatment with a surfactant in order to improve the affinity of the hydrophobic polypropylene fiber for concrete. As the surface treatment with this surfactant, in particular, it is composed of polyoxyalkylene alkylphenyl ether phosphate (A) and polyoxyalkylene fatty acid ester (B), and the weight ratio of (A) / (B) is 60/40. It is preferable to apply a fiber treating agent of about 40/60 to 0.01 to 2% by weight based on the total fiber. This (A)
If the weight ratio of / (B) is out of this range, the polypropylene fiber treated in the cement slurry causes a floating phenomenon, and the dispersibility deteriorates. The following simple tests were performed on the ratio of this surfactant and its effect. (A) / (B) was changed to a surfactant applied to a polypropylene fiber,
A slurry was prepared by sufficiently kneading the polypropylene fiber and the cement, allowed to stand for about 5 minutes, and the polypropylene fiber floating on the water surface was calculated with respect to the input amount. Table 1 shows the results. (B) No fibers floating on the slurry in the range of 60/40 to 40/60 were found at all.

[0024]

[Table 1]

The polyoxyalkylene alkylphenyl ether phosphate (A) can be represented by the following general formula (1). R ₁ is an alkyl-substituted phenyl group;
The alkyl group usually has 8 to 12 carbon atoms. R ₂ is an ethylene group or a 1,2-propylene group, preferably an ethylene group. X is 2 is a monoester, X is 1
Is a diester.

[0026]

Embedded image

Specific examples of the polyoxyalkylene alkyl phenyl ether phosphate (A) include polyoxyethylene nonyl phenyl ether phosphate, polyoxyethylene dodecyl phenyl ether phosphate and the like.

The above polyoxyalkylene fatty acid ester
(B) can be represented by the general formula (2). R ₃ is an alkyl or allyl group having 12 to 20 carbon atoms, preferably an alkyl or allyl group having 16 to 18 carbon atoms.

[0029]

Embedded image

The above polyoxyalkylene fatty acid ester
Specific examples of (B) include polyoxyethylene oleate and polyoxyethylene stearate.

The above polyoxyalkylene alkyl phenyl ether phosphate (A) and polyoxyalkylene fatty acid ester (B) are obtained by the following method.
Preferably the value is between 8 and 14.

[0032]

HLB = E / 5 (E = weight fraction of polyoxyalkylene moiety)

In the above range of the HLB value, the molecular weight of polyethylene glycol is appropriately adjusted, so that it has excellent affinity for resins and also has excellent hydrophilicity.

The amount of the surface treatment agent adhered to the fibers is as follows:
0.01 to 2% by weight based on the total fiber, preferably 0.05 to 0.5%
% By weight. If the adhesion amount is less than 0.01% by weight based on the total fiber, the hydrophilicity is not sufficiently imparted to the polypropylene fiber, and
If it exceeds 10% by weight, the hydrophilicity reaches a peak, the convergence of the polypropylene fibers becomes stronger, and the dispersibility in the cement slurry is poor.

Such a polypropylene monofilament is cut into a predetermined length to be a short fiber for cement reinforcement. The length of the short fibers is 5 to 60 mm, preferably 20 to 35 mm. If the fiber length is less than 5 mm, detachment from the cement occurs, and if it exceeds 60 mm, the dispersibility becomes poor, which is not preferable.

The polypropylene fiber for cement reinforcement of the present invention is used by mixing it with cement, fine aggregate, coarse aggregate, water and an appropriate amount of concrete admixture as a reinforcing fiber material.
Here, as the cement, Portland cement, blast furnace cement, silica cement, fly ash cement,
Examples include hydraulic cements such as white Portland cement and alumina cement or cements such as air-hardened cements such as gypsum and lime.Fine aggregates include river sand, sea sand, mountain sand, silica sand, glass sand, iron sand, and ash. Sand, other artificial sand, etc. are mentioned, and as coarse aggregate, reki, gravel, crushed stone, slag,
Typical examples include various artificial lightweight aggregates.

When the cement-reinforced polypropylene fiber of the present invention is used for the construction of shotcrete, the amount of the polypropylene fiber is based on 1 m ^{3 of a} concrete mixture comprising cement, fine aggregate, coarse aggregate, water and the like. 4.5-1
It is important to mix and disperse 8.5 kg, preferably 6.5 to 14.0 kg. This is because even if the blending amount of polypropylene fiber exceeds 18.5 kg, the toughness does not increase because the fiber is not evenly distributed in the concrete, while if the blending amount is less than 4.5 kg, the rebound during spraying is large, Further, the reinforcing effect after curing is small.

As a mixing method in this case, a concrete mixture composed of cement, fine aggregate, coarse aggregate, water and the like is put into a base concrete, and after kneading the base concrete, polypropylene fibers are put and kneaded. The kneading time depends on the amount of mixing per operation.
~ 90 seconds, kneading after adding polypropylene fiber
A range between 45 and 90 seconds is appropriate.

In addition, in the construction of shotcrete, when the polypropylene fiber of the present invention is used in the above-mentioned amount, it is preferable to adjust the slump range to 8 to 21 cm. If the slump is less than 8 cm, the spraying operation becomes difficult, and if the slump exceeds 21 cm, the rebound increases, which is not preferable. For spraying nozzles for applying shotcrete in such a slump range, it is effective to arrange the nozzles at right angles to the spraying surface and to make the distance between the nozzle and the spraying surface 0.5 to 1.5 m. Becomes

[0040]

EXAMPLES Hereinafter, the effectiveness of the polypropylene fiber of the present invention and the method of applying shotcrete using the same will be described with reference to examples.

Production of Fiber Polypropylene (MFR = 4.0 g / 10 min., Tm = 163 ° C.) was put into an extruder, spun from a circular nozzle, cooled, and then subjected to a hot drawing temperature of 115 ° C. by a hot air oven drawing method. The film is stretched at a heat relaxation temperature of 120 ° C. and a draw ratio of 7 to 8 times to form monofilaments of several types of fineness. Then, the emboss nip pressure is changed by using an embossed roll having a sloping lattice pattern and a hard rubber roll, and the average flatness is changed. The polypropylene monofilaments having irregularities formed on the different surfaces were obtained. An example of this uneven shape is as shown in the micrograph of FIG. Magnification is 50
In the photograph, D represents the diagonal unit length of the embossed pattern, H represents the repetition length in the longitudinal direction (mm), and U represents the width (mm) of the flat system.

On the surface of these polypropylene monofilaments, a polyoxyalkylene alkylphenyl ether phosphate (HLB = 9) 50 was used as a surfactant.
Parts by weight and polyoxyalkylene fatty acid ester (H
LB = 12) 50 parts by weight are mixed, and the polypropylene monofilament is immersed in an aqueous solution of a surface treating agent and dried, so that 0.28% by weight is attached to the total fiber, and then the fiber length becomes 30 mm. Into polypropylene fibers.

Evaluation Test In addition to the polypropylene fiber thus obtained, the concrete reinforcing effect was tested, including a comparison between a commercially available reinforcing fiber and polyvinyl alcohol fiber (the fiber length was all 30 mm).

(1) Materials used and mixing ratio Cement: Portland cement with early strength (specific gravity = 3.12) 43
0kg / m ³ fine aggregate: Kisarazu production Mountain sand (Table dry specific gravity = 2.60) 1123kg / m ³ Coarse aggregate: Ome production crushed stone 1505 (Table dry specific gravity = 2.65) 491kg / m ³ water: tap water 215kg / m ³ fiber : 1% by volume

(2) Concrete kneading method Using a forced pan type mixer having a kneading capacity of 100 liters,
Perform in batches of 50 liters. The temperature at the time of concrete kneading was about 20 ° C. The kneading method is fine aggregate, cement,
After adding water and coarse aggregate and kneading for 45 seconds, the reinforcing fibers are added while rotating the mixer, kneading is performed for 60 seconds, and the mixture is discharged.

(3) Preparation of Specimen The method was based on JSCE F552-1983, "How to make a specimen for strength and toughness test of steel fiber reinforced concrete". The specimen was released after 24 hours, and was cured in water until the age of 7 days.

(3) Test method JSCE G551-1983, JSCE standard "Testing method for flexural strength and flexural toughness of steel fiber reinforced concrete" (JSCE G552-1983).

The fibers used in this test and the test results are summarized in Table 2.

[0049]

[Table 2]

From the results shown in Table 2, the fibers of Example 1, Example 2 and Example 3 have fineness and flatness due to embossment within the range of the present invention. Sufficient reinforcement effect of the same level was confirmed. Next, comparing Example 1 and Comparative Example 1, the reinforcing effect of Example 1 in which irregularities were formed on the surface by embossing while having the same fineness was recognized, and Comparative Example 1 having a simple flat monofilament shape was inferior in the reinforcing effect. You can check. Comparative Example 2 had a low fineness, but did not produce a sufficient reinforcing effect even when embossed, and Comparative Example 3 increased the pressure by embossing, resulting in a tape shape exceeding the flatness of the present invention. Because of the deterioration, strength reduction is large and sufficient reinforcing effect does not occur,
It was confirmed that the dispersibility was not good.

Next, a similar test was conducted using the polypropylene fiber of Example 2 while changing the blending ratio in the concrete mixture. As a result, the relationship between the blending amount of the fiber and the bending toughness was shown in FIG. Shown in From FIG. 2, the reinforcing effect is excellent in the range of 4.5 to 18.5 kg / m ³ as the fiber weight, that is, in the range of 0.5 to 2% with the peak at around 1% as the capacity. In the spraying construction, the rebound is large and impractical.Conversely, if there are too many fibers, it is difficult to disperse uniformly in the concrete, resulting in a decrease in strength and poor workability such as poor pumpability for spraying. It becomes a problem.

[0052]

As described above, the cement reinforcing polypropylene fiber of the present invention has irregularities on the surface, and the irregularities significantly improve the physical bonding to the concrete, and the material separation of the concrete. Thus, pulling out of the cured fiber can be suppressed, and a reinforcement effect comparable to that of steel fiber can be expected.

Therefore, in the construction of the shotcrete, the specific gravity of the polypropylene fiber is extremely light at 0.91, so that the work of transporting and putting in the material becomes easy. In the spraying work, the amount of rebound can be reduced and the bending toughness increases, so that it can follow the behavior of the ground, so that the loosening of the ground decreases, the bearing strength of the shotcrete increases, leading to the stability of the tunnel At the same time, a reinforcing wire mesh as a construction method member is not required, thereby shortening the construction period and reducing costs. Further, there is little risk of injury due to stepping out of a fiber dropped by splashing such as steel fiber when sprayed. In addition, polypropylene fiber has a high tensile strength, so the effect of preventing cracking of sprayed concrete also increases, and rust does not occur, so that the appearance of the concrete is not impaired, and the fiber itself has no water absorption, so the quality of fresh concrete Is stable. Incidentally, in the present invention, without being limited to shotcrete, spray mortar, the bending strength of ordinary concrete and mortar, bending toughness, since the effect is recognized in increasing the tensile strength and preventing the occurrence of cracks, etc. Needless to say, it can be applied to this.

[Brief description of the drawings]

FIG. 1 is a photomicrograph (× 50) of a polypropylene fiber having an irregular surface.

FIG. 2 is a graph showing the relationship between the blending amount of polypropylene in a spray mixed slurry and the flexural toughness of concrete after spray solidification.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI E21D 11/10 E21D 11/10 D (73) Patent holder 391005891 VSL Japan Co., Ltd. 3 Nishishinjuku, Shinjuku-ku, Tokyo Hachiwara Kogyo Co., Ltd. 1-4-2, Mizushima Nakadori, Kurashiki-shi, Okayama Pref. (72) Inventor Masuo Yabuki Masushima Nakadori, Kurashiki-shi, Okayama 1-4, Hagiwara Kogyo Co., Ltd. (72) Inventor Hiroshi Ikeda 25-1, 1-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Taisei Corporation (72) Inventor Kuniaki Kataoka 1-chome, Nishi-Shinjuku, Shinjuku-ku, Tokyo 25-1 Daisei Construction Co., Ltd. (72) Zenfu Sakamoto, Inventor 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Daisei Construction Co., Ltd. (72) Inventor Masahiko Kobayashi 1-Shibuya, Shibuya-ku, Tokyo 20 -24 Shibuya Sky Irishtel 206, Nippon Shoji Co., Ltd. (72) Inventor Tatsuo Saito 3-26 Nishi-Shinjuku, Shinjuku-ku, Tokyo VSL Japan Co., Ltd. (56) References JP JP-A-9-183646 (JP, A) JP-A-5-178649 (JP, A) JP-A-57-156363 (JP, A) JP-A-63-303837 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) C04B 16/06 B28B 1/32

Claims (2)

(57) [Claims] 1. A monofilament having a single yarn fineness of 200 to 10,000 dr, which is spun from a polypropylene resin and has irregularities on the surface with an average flatness of the fiber cross section in the range of 2/1 to 7/1.
To polyoxyalkylene alkyl phenylate
Telluric acid ester (A) and polyoxyalkylene fat
Consisting of fatty acid ester (B), the weight ratio of (A) / (B) is 60 / 40-4
0/60 fiber treatment agent 0.01 to 2% by weight based on total fiber
A polypropylene fiber for cement reinforcement adhered and cut to a fiber length of 5 to 60 mm. 2. A 1 m ³ concrete mixture comprising cement, fine aggregate, coarse aggregate, water and the like is spun from a polypropylene resin, and the average flatness of the fiber cross section on the surface is 2/1.
Single yarn fineness 200 ~ 10,000d with irregularities in the range of ~ 7/1
Polyoxyalkylene for monofilament of r
Alkyl phenyl ether phosphate (A)
Lioxyalkylene fatty acid ester (B), (A) /
The fiber treatment agent having a weight ratio of (B) of 60/40 to 40/60
Of sprayed concrete using polypropylene fibers for cement reinforcement, characterized in that 4.5 to 18.5 kg of fibers obtained by adhering 0.01 to 2% by weight to fibers and cutting to a fiber length of 5 to 60 mm are mixed and sprayed. Construction method.