JPH11152617A - Fiber for reinforcing concrete and concrete molding using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber for reinforcing concrete useful for working board, etc., having a large shock absorbing energy, capable of improving flexural strength and compressed strength of a concrete molding, showing excellent reinforcing effects, by making the fiber include a fiber of high elongation having a single fiber elongation of a prescribed value or higher than it. SOLUTION: This fiber comprises (A) preferably 30-100 wt.% of a fiber of high elongation having >=500%, >=1,000% single fiber elongation, for example, a polyolefin-based fiber such as a polypropylene, etc., and more preferably (B) preferably 0-70 wt.% of a fiber of high strength having >=5 g/d, preferably >=7 g/d single fiber strength, for example, a polyolefin-based fiber, etc. Preferably at least one of the components A and B is coated with 0.1-10 wt.% based on the composition A or B of a surfactant which is selected from among a higher fatty acid metal salt, a higher alcohol sulfuric ester metal salt, an alkylbenzene sulfonic metal salt, etc., and contains a 8-22C alkyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber for reinforcing concrete having an excellent concrete reinforcing effect. More specifically, the present invention relates to a concrete reinforcing fiber suitably used for a concrete molded body mainly composed of building materials such as construction boards and tiles, and a concrete molded body formed using the concrete reinforcing fiber.

[0002]

2. Description of the Related Art Hardened cement is widely used in the fields of construction and civil engineering because of its low cost in addition to excellent properties such as compressive strength, durability and nonflammability. However,
Because it is a brittle material, it has extremely low flex resistance,
It easily breaks or cracks when bending stress is applied,
There are drawbacks such as low impact resistance. In recent years, in order to solve these problems, use of various inorganic fibers and organic synthetic fibers as fibers for reinforcing cement has been proposed. However, the properties of the fibers cannot be used effectively, or the fibers have both advantages and disadvantages, and the effects cannot be sufficiently exhibited.
The concrete reinforcement effect has not reached a satisfactory level. For example, olefin fibers have alkali resistance and heat resistance, and can be cured in an autoclave or steam, which is advantageous for concrete reinforcement. However, the surface of the olefin fiber is hydrophobic, has poor adhesion to a hydrophilic cement matrix, and has poor dispersibility in a cement slurry. As a prior art for solving this problem, there is known a technique in which fibers are subjected to surface treatment with a surfactant or the like to improve affinity with cement. (Japanese Patent Laid-Open No. 4-2
1556, JP-A-5-170497, PCT International Publication W
O90 / 06902 etc.). In recent years, in order to improve dispersibility and affinity, and to improve the reinforcing effect, the cross section of the fiber is deformed, projections or nodes are formed on the fiber surface, or the surface is coated with other components. There have been proposed improvement measures such as improving fiber strength, kneading other components, and specializing raw materials, but have not yet reached a satisfactory range.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a concrete reinforcing fiber which has a large impact absorption energy and is capable of improving the bending strength and compressive strength, particularly the impact strength, of a concrete molding. is there.

[0004] The present inventors have conducted intensive studies to achieve the above-mentioned object, and as a result, have taken advantage of the knowledge on the physical properties of fibers and the reinforcement of concrete to maintain not only the strength but also the elongation of fibers at a high level. Is important as the basis of concrete reinforcement. In addition, concrete reinforcing fibers having a hydrophobic fiber surface, such as polyolefin fibers, include higher fatty acid metal salts, higher alcohol sulfate metal salts, and higher alkyl ethers. At least one alkyl group having 8 to 22 carbon atoms selected from the group consisting of a metal salt of a sulfate ester, a metal salt of an alkylbenzenesulfonic acid, a metal salt of an alkylbenzenenaphthalenesulfonic acid, a metal salt of a paraffinsulfonic acid, an alkylamine salt, and an alkylammonium salt; Impact on the surface of the fiber This fiber is used as a fiber for concrete reinforcement because the energy absorption is increased, and the affinity and dispersibility with the cement matrix are improved, and the bending strength and compressive strength of the concrete molded body, especially the impact strength are improved. The present invention was found to be suitable, and it was found that a concrete molded article formed by using the fiber exhibited extremely excellent impact strength, thereby completing the present invention.

[0005]

The present invention has the following arrangement to solve the above-mentioned problems. (1) Concrete reinforcing fiber containing high elongation fiber (A) having a single yarn elongation of 500% or more. (2) 30 high elongation fibers (A) having a single yarn elongation of 500% or more
Concrete reinforcing fiber comprising 0 to 70% by weight of a high-strength fiber (B) having about 100% by weight and a single yarn strength of 5 g / d or more. (3) The concrete reinforcing fiber according to the above item 1 or 2, wherein the high elongation fiber (A) has a single yarn elongation of 1000% or more. (4) The concrete reinforcing fiber according to the above item 2 or 3, wherein the high-strength fiber (B) has a single-yarn strength of 7 g / d or more. (5) The concrete reinforcing fiber according to any one of the above items 1 to 4, wherein the high elongation fiber (A) or the high strength fiber (B) is a polyolefin fiber. (6) A metal salt of a higher fatty acid, a metal salt of a higher alcohol sulfate, a metal salt of an alkyl benzene sulfonic acid,
The surfactant having at least one kind selected from the group consisting of a metal salt of an alkylbenzene naphthalene sulfonic acid, a metal salt of a paraffin sulfonic acid, an alkylamine salt and an alkylammonium salt and having an alkyl group having 8 to 22 carbon atoms is preferably used. 6. The concrete reinforcing fiber according to any one of the above items 1 to 5, wherein 0.1 to 10% by weight is attached to the weight of the strength fiber (A) or the high elongation fiber (B). (7) The fiber for concrete reinforcement according to the item 6, wherein the metal salt is at least one kind of alkali metal salt selected from Na, Li, and K. (8) A concrete molded article molded using the concrete reinforcing fiber according to any one of the above items 1 to 7.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The concrete reinforcing fiber of the present invention is a concrete reinforcing fiber containing a high elongation fiber (A) having a single yarn elongation of 500% or more.

[0007] Preferably, the concrete reinforcing fiber of the present invention comprises a high elongation fiber (A) having a single yarn elongation of 500% or more.
Concrete reinforcing fiber comprising 0 to 70% by weight of high strength fiber (B) having 30 to 100% by weight and single yarn strength of 5 g / d or more. More preferably, the high elongation fiber (A) is a single yarn elongation
It is preferably at least 1000%. The high-strength fiber (B) preferably has a single yarn strength of 7 g / d or more. Still more preferably, it is desirable that the high-strength fiber (B) has a single-yarn strength of 7 g / d or more and the high-strength fiber (A) has a single-yarn elongation of 1000% or more.

[0008] A concrete molded body using the concrete reinforcing fiber has a large impact absorption energy. By increasing the impact absorption energy, the bending strength and the compressive strength, particularly the impact strength, of the concrete molded body are improved. The term "impact absorption energy" as used herein refers to energy from the time when a concrete molded body receives a stress until the stress after rupture becomes zero.

The cross-sectional shape of the fiber serving as the base material of the concrete reinforcing fiber used in the present invention may be circular or irregular. In the case of an irregular cross-section, any shape such as a flat shape, a square shape such as a triangular to octagonal shape, a T-shape, a multi-lobe shape, a hollow cross-sectional shape, etc., is not particularly limited. The shape of the fiber surface, such as the presence or absence of irregularities and the presence or absence of surface roughness due to other materials, is not particularly limited. Further, the length, thickness, mixing ratio, type of cement, type of aggregate, and method of producing a concrete molded product are not particularly limited.

The type of the fiber for reinforcing concrete of the present invention may be any of inorganic fiber, organic synthetic fiber, natural fiber and the like, and it is particularly limited as long as it has a single yarn elongation of 500% or more. Not something.

[0011] Desirably, polyolefin fibers are used. In particular, polyolefin-based fibers mainly composed of polypropylene are particularly excellent in the improvement of impact absorption energy.

When the polypropylene fiber which is a polyolefin fiber is used as a fiber for concrete reinforcement, the polypropylene fiber used as the base material is composed of 100% propylene units of the raw material polypropylene and 2% by weight or less in other polymers. It may be a substantial polypropylene homopolymer containing an ethylene unit or an α-olefin unit such as butene-1, pentene-1,4-methylpentene-1, hexene-1, octene-1, etc. having C4 or more. . Further, a mixture of a crystal random copolymer or a block copolymer of propylene, ethylene and olefin may be used as the polypropylene resin.

The polypropylene resin according to the present invention includes:
Further, within the range not hindering the effects of the present invention, an antioxidant,
Light stabilizers, ultraviolet absorbers, neutralizers, nucleating agents, epoxy stabilizers, lubricants, antibacterial agents, flame retardants, antistatic agents, pigments, plasticizers, etc. Good.

Next, as a raw material of a polypropylene fiber which is a fiber (A) having a single yarn elongation of 500% or more as a base material of the concrete reinforcing fiber of the present invention, the Q value is 4 or less and the melt flow rate is 1 to 4. A production method using a polypropylene resin of 30 g / 10 min will be described. First, spinning is preferably performed at a spinning temperature in the range of 250 to 350 ° C, and more preferably in the range of 310 to 340 ° C, because it is possible to obtain an undrawn yarn with reduced fiber orientation.
When the spinning temperature is less than 250 ° C., the fibrous polypropylene melt extruded from the spinneret from the polypropylene melt melted by the extruder is rapidly cooled, and the fiber deformation at the solidification point is large, and the orientation is further advanced. However, it is not preferable because it is an undrawn yarn. In addition, when the spinning temperature exceeds 350 ° C, the decomposition of the polypropylene resin rapidly progresses, and it is difficult not only to obtain an undrawn yarn having good spinnability due to fiber firing, but also the molecular chains of the fiber are severely cut. As a result, the molecular weight is not reduced to the desired high elongation polypropylene fiber.

When the extruded fibrous polypropylene melt is cooled, conventional methods such as air, water,
It can be cooled in a medium such as glycerin or the like to a temperature lower than the melting point, and can be drawn. However, in order to suppress the orientation of the undrawn yarn as much as possible, it is preferable to cool with air instead of quenching with liquid. Air temperature and air volume can be set arbitrarily,
In order to obtain an undrawn yarn with further suppressed orientation, it is preferable that the temperature is gradually cooled, that is, the air volume is weak and the temperature is not too low.
Such slow cooling is preferable because a higher-order crystal structure in which the lamellas are arranged at right angles to the fiber axis direction can be sufficiently formed.

The take-up speed of the undrawn yarn is 200 to 1000 m / m in order to make the undrawn yarn in which the deformation at the solidification point of the fibrous polypropylene melt is small and the orientation does not proceed.
It is preferably in. More preferably, it is preferable to take off at as low a speed as possible, so as not to be less than 200 m / min. On the other hand, if the take-up speed is 1000 m / min or more, the fibrous polypropylene melt is greatly deformed at the solidification point, becomes an oriented undrawn yarn, and the elongation is reduced. On the other hand, if it is less than 200 m / min, high-temperature spinning cannot produce a uniform undrawn yarn which is slower than the natural falling speed of the polypropylene melt having a lowered melt viscosity.

Next, stretching will be described. The polypropylene undrawn yarn obtained by the above-described method is drawn to obtain a polypropylene fiber having high elongation. A known method such as hot roll drawing, hot water drawing, and a heating plate is employed as a method for drawing the undrawn polypropylene yarn. The stretching operation can be performed by any of one-stage stretching, two-stage stretching, and multi-stage stretching.
It is preferable to perform two or more stretching operations rather than one-stage stretching. Stretching is performed at a relatively low temperature of 50 to 90 ° C. When drawn at a temperature of 90 ° C. or higher, the oriented crystallization of the undrawn yarn proceeds rapidly, and at a temperature lower than 50 ° C., the drawability is reduced and the elongation is significantly reduced. Further, the polypropylene undrawn yarn obtained by the above method may be used as a concrete reinforcing fiber without performing the drawing step. In order to obtain a polypropylene fiber having an elongation of 1000% or more, the stretching step is preferably omitted.

The stretching ratio at this time is preferably in the range of 1.0 to 1.8 times. If it exceeds 1.8 times, the single yarn elongation will decrease. Next, in the case of performing two-stage stretching, one-stage stretching requires a total stretching ratio of 40%.
% Or more, preferably at a stretch ratio of 50% or more.
Stretched to the extent that single yarn breakage and fluffing do not occur at the stage,
It is preferable that the total stretching ratio be within the above range. When the single-stage stretching is performed at a stretching ratio of less than 40% of the total stretching ratio, even if the total stretching ratio is the same as compared to the case where the single-stage stretching is performed at 40% or more of the total stretching ratio, a high elongation is obtained. No polypropylene fiber can be obtained. This is because orientation crystallization remarkably progresses in one-stage stretching, and stretching in two or more stages results in excessive stretching, resulting in lower elongation. Here, the stretching ratio is represented by a ratio between a supply roll speed and a take-up roll speed.

Further, by subjecting the drawn product of the drawn polypropylene fiber to an annealing treatment at a temperature near the melting point by a constant-length heat treatment, a relaxation heat treatment, or the like, a polypropylene fiber having improved heat shrinkage can be obtained.

Through such a spinning and drawing process, a polypropylene fiber having a physical property of a single yarn elongation of 500% or more can be obtained. In particular, when the fiber is spun at a high temperature of 310 ° C. or higher, and the low-temperature drawing or the drawing step is omitted, a high elongation polypropylene fiber having a single yarn elongation of 500% or more, which is optimal for concrete reinforcement, can be obtained.

Further, as a raw material of a polypropylene fiber which is a fiber (B) having a single yarn strength of 5 g / d or more as a base material of the concrete reinforcing fiber of the present invention, the Q value is 4 or less, and the melt flow rate is 1 to 4. A production method using a polypropylene resin of 30 g / 10 min will be described. First, spinning is preferably performed at a spinning temperature in the range of 250 to 350 ° C, and more preferably in the range of 310 to 340 ° C, because it is possible to obtain an undrawn yarn with reduced fiber orientation.
When the spinning temperature is less than 250 ° C., the fibrous polypropylene melt extruded from the spinneret from the polypropylene melt melted by the extruder is rapidly cooled, and the fiber deformation at the solidification point is large, and the orientation is further advanced. However, it is not preferable because it is an undrawn yarn. In addition, when the spinning temperature exceeds 350 ° C, the decomposition of the polypropylene resin rapidly progresses, and it is difficult not only to obtain an undrawn yarn having good spinnability due to fiber firing, but also the molecular chains of the fiber are severely cut. Even if it is reduced in molecular weight and stretched, it does not become a high-strength polypropylene fiber.

When the extruded fibrous polypropylene melt is cooled, conventional methods such as air, water,
It can be cooled in a medium such as glycerin or the like to a temperature lower than the melting point, and can be drawn. However, in order to suppress the orientation of the undrawn yarn as much as possible, it is preferable to cool with air instead of quenching with liquid. Air temperature and air volume can be set arbitrarily,
In order to obtain an undrawn yarn with further suppressed orientation, it is preferable that the temperature is gradually cooled, that is, the air volume is weak and the temperature is not too low.
Such slow cooling is preferable because a higher-order crystal structure in which the lamellas are arranged at right angles to the fiber axis direction can be sufficiently formed.

The winding speed of the undrawn yarn is 200 to 1000 m / m in order to reduce the deformation at the solidification point of the fibrous polypropylene melt and to make the undrawn yarn unoriented.
It is preferably in. More preferably, it is preferable to take off at as low a speed as possible, so as not to be less than 200 m / min. On the other hand, if the take-up speed is 1000 m / min or more, the fibrous polypropylene melt is greatly deformed at the solidification point, becomes an oriented unstretched yarn, has poor stretchability, and cannot be stretched at a high magnification. On the other hand, if it is less than 200 m / min, high-temperature spinning cannot produce a uniform undrawn yarn which is slower than the natural falling speed of the polypropylene melt having a lowered melt viscosity.

Next, stretching will be described. The polypropylene undrawn yarn obtained by the above-described method is drawn to obtain a high-strength polypropylene fiber. A known method such as hot roll drawing, hot water drawing, and a heating plate is employed as a method for drawing the undrawn polypropylene yarn. The stretching operation can be performed by any of one-stage stretching, two-stage stretching, and multi-stage stretching.
It is preferable to perform two or more stretching operations rather than one-stage stretching. Stretching is performed at a relatively low temperature of 50 to 90 ° C. When drawn at a temperature of 90 ° C. or more, the oriented crystallization of the undrawn yarn proceeds rapidly, and at a temperature lower than 50 ° C., the drawability is reduced and the draw ratio required for high strength cannot be obtained.

The stretching ratio at this time is preferably in the range of 4.2 times or more. If it is less than 4.2 times, the single yarn strength is low and does not reach the target strength. Next, when performing two-stage drawing, the film is drawn at a draw ratio of 40% or more, preferably 50% or more of the total draw ratio in one-step drawing, and then to a range where single yarn breakage and fluffing do not occur in the second step. It is preferable that the film is stretched and the total stretching ratio is within the above range. Even if the total stretching ratio is the same as the case where the single-stage stretching is performed at a stretching ratio of less than 40% of the total stretching ratio and the single-stage stretching is performed at 40% or more of the total stretching ratio, the high-strength polypropylene is used. Fiber cannot be obtained. This is because the oriented crystallization remarkably progresses in one-stage stretching, and in two or more stages stretching, unreasonable stretching occurs, and as a result, the strength does not increase. Here, the stretching ratio is represented by a ratio between a supply roll speed and a take-up roll speed.

Further, by subjecting the drawn product of the drawn polypropylene fiber to an annealing treatment at a temperature near the melting point by a constant-length heat treatment, a relaxation heat treatment, or the like, a polypropylene fiber having improved heat shrinkage can be obtained.

Through such a spinning and drawing process, a polypropylene fiber having physical properties of a single yarn strength of 5 g / d or more can be obtained. In particular, spinning at a high temperature of 310 ° C. or higher and low-temperature drawing or two-step drawing can provide a high-strength polypropylene fiber having a single-strength strength of 7 g / d or more, which is optimal for concrete reinforcement.

Preferably, the surface of the polypropylene fiber is treated with a surfactant or the like to improve the affinity with the cement.

The surfactant may be attached to the polypropylene fiber in any of the spinning step and the drawing step. The adhesion method is a roller method, a dipping method, a spray method,
A pad dry method or the like can be used. Preferably, the attachment in the spinning step and the drawing step may provide uniform attachment.

As a treating agent for the surface of the polyolefin fiber, a metal salt of a higher fatty acid,
At least one selected from the group consisting of higher alcohol sulfate metal salts, higher alkyl ether sulfate metal salts, alkylbenzenesulfonic acid metal salts, alkylbenzenenaphthalenesulfonic acid metal salts, and paraffinsulfonic acid metal salts; A surfactant containing an alkyl group and at least one alkali metal salt selected from Na, Li, and K is used as a metal salt. 0.1 to 10% by weight of the surfactant is attached to the weight of the polyolefin fiber. The method can be exemplified.

By attaching the above-mentioned surfactant to the surface of the polyolefin fiber, the affinity for cement and the dispersibility are improved. The surfactant is a compound having both polarities of a hydrophilic group and a hydrophobic group. By adhering the surfactant to the surface of the polyolefin-based fiber, between the hydrophobic polyolefin-based fiber and the surfactant, hydrophobic groups have an affinity between the hydrophobic groups and a binding force is obtained,
Between the surfactant and the cement, the hydrophilic groups face each other and the calcium ions in the cement and the salt of the surfactant are replaced, and the calcium salt of the surfactant becomes an insoluble and sticky substance, Cement particles adhere to the surface of the concrete reinforcing fiber. That is, by interposing the surfactant between the polyolefin-based fiber and the cement, the adhesion between the cement and the concrete reinforcing fiber is strengthened and the affinity is improved, and the concrete reinforcing fiber is uniformly dispersed in the cement. And the dispersibility is improved. If the amount of adhesion is less than 0.1% by weight, the above effect is not sufficiently obtained, and if the amount exceeds 10% by weight, the effect becomes saturated, and the bending strength, the impact strength, and the bending impact energy absorbing ability reach equilibrium. It is uneconomical.

The concrete reinforcing fiber of the present invention is a high elongation fiber (A) having a single yarn elongation of 500% or more, preferably 1000% or more. More preferably, it is used in a mixed blend with a high-strength fiber (B) having a single yarn strength of 5 g / d or more, more preferably 7 g / d or more. When a concrete molded article mixed with the fiber is stretched in the X-axis and a bending stress is applied in the Y-axis, the impact absorption energy increases in the X-axis direction because the single fiber elongation is 500% or more. I do.
When the single yarn strength is 5 g / d or more, the impact absorption energy increases in the Y-axis direction. That is, single yarn elongation 500%
The impact energy increases in one direction due to the above high elongation fiber (A), but the impact absorption energy in two directions is increased by mixing and blending the high strength fiber (B) with a single yarn strength of 5 g / d or more. In order to improve, the flexural strength and compressive strength, especially impact strength, of the concrete molded body are significantly increased.

[0033]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Regarding the method for evaluating the physical properties of the concrete molded body, the measurement of the bending strength was performed according to JIS-A1408. The impact strength was measured according to JIS-B7722 Charpy impact test.

Table 1 shows fiber production methods and yarn properties used in "Examples 1 to 9 and Comparative Examples 1 and 2". The melt flow rate in the table was measured according to JIS-K7210, and the measurement of single-strength elongation was performed according to JIS-L-1015. Also, Q
The value is weight average molecular weight / number average molecular weight.

[0035]

[Table 1]

Example 1 0.18 kg of the polypropylene fiber (1) in Table 1 was mixed with 18 kg of ordinary Portland cement and 6 liters of water, and the mixture was compressed at a pressure of 120 kg / cm ² for 10 seconds. One sample was 30 cm × 25 cm × 1.1 cm. A compact was formed at a size of. This compact is
After aging in steam at 5 ° C. for 5 hours, the sample was left in a room for 28 days to measure the measurement items.

Example 2 A concrete molded product was obtained in the same manner as in Example 1 except that the fiber was obtained by adhering 2.2% by weight of potassium oleate to the surface of the polypropylene fiber in Table 1 (1). .

Example 3 Except that the fiber was the polypropylene fiber of (2) in Table 1,
In the same manner as in Example 1, a concrete molded body was obtained.

Example 4 The fiber was prepared by mixing 50% of the polypropylene fiber of Table 1 (3) with the fiber of Table 1.
A concrete molded product was obtained in the same manner as in Example 1 except that the fiber mixture of (4) was made of 50% polypropylene fiber.

Example 5 The fiber was prepared by mixing 30% of the polypropylene fiber of Table 1 (3) with the fiber of Table 1.
A concrete molded product was obtained in the same manner as in Example 1 except that the mixed fiber of (4) was made of 70% of polypropylene fiber.

Example 6 A fiber was prepared by mixing 70% of the polypropylene fiber of Table 1 (3) with the fiber of Table 1.
A concrete molded product was obtained in the same manner as in Example 1 except that the fiber mixture of (4) was used, in which the polypropylene fiber was 30%.

Example 7 A fiber was prepared by mixing 50% of the polypropylene fiber of Table 1 (5) with the fiber of Table 1.
A concrete molded product was obtained in the same manner as in Example 1 except that the fiber mixture of (6) was made of 50% of polypropylene fiber.

Example 8 A fiber was prepared by mixing 50% of the polypropylene fiber of Table 1 (7) with the fiber of Table 1.
A concrete molded product was obtained in the same manner as in Example 1, except that the fiber mixture of (8) was made of 50% of polypropylene fiber.

Example 9 The fiber was prepared by mixing 50% of the polypropylene fiber of (9) in Table 1 with (1) in Table 1.
A concrete molded article was obtained in the same manner as in Example 1 except that the fiber mixture of 0) was made of 50% polypropylene fiber.

Comparative Example 1 A concrete molding was obtained in the same manner as in Example 1 except that the fiber was not used.

COMPARATIVE EXAMPLE 2 Except that the fiber was the polypropylene fiber of (11) in Table 1,
In the same manner as in Example 1, a concrete molded body was obtained.

The above Examples 1 to 9 and Comparative Examples 1 to 9
Table 2 shows the results of evaluating the physical properties of the 2 "concrete molded product.

[0048]

[Table 2]

As is clear from Table 2, Examples 1 to 9 are superior in flexural strength and compressive strength, particularly impact strength, of the concrete molded product.

Examples 1 to 9 are superior to Comparative Examples 1 and 2 in terms of flexural strength and compressive strength, particularly impact strength, of the concrete molded product. Example 2 shows the effect of performing the fiber surface treatment of Example 1. In Example 3, the effect of reinforcing a high elongation yarn having a single yarn elongation of 1000% or more is remarkable. In Examples 4 to 9, more excellent bending strength and impact strength can be obtained because they are used as a blend with fibers having a single yarn strength of 5 g / d or more or 7 g / d or more. Particularly, as shown in Example 9, a fiber having a single yarn strength of 7 g / d or more and a single yarn elongation of 10 g / d were used.
It is clear that the mixing strength of the fibers of not less than 00% significantly increases the flexural strength and the compressive strength, especially the impact strength of the concrete molding.

In Comparative Example 1, the flexural strength and compressive strength, particularly impact strength, of the concrete molded product were low because no fiber with a single yarn elongation of 500% was added.

In Comparative Example 2, the fiber was added, but the single yarn elongation was less than 500%, so that a sufficient effect was not obtained.

[0053]

The fiber for reinforcing concrete of the present invention has an excellent concrete reinforcing effect. That is, it shows improvement in bending strength and compressive strength, particularly impact strength of the concrete molded body. Due to the high single yarn elongation of the concrete reinforcing fiber, the elongation stress of the concrete molded body is improved, and the impact absorption energy is increased. Therefore, it shows improvement in bending strength and compressive strength, particularly impact strength of the concrete molded body. In addition, by mixing and blending the concrete reinforcing fiber with a high single-strength fiber, the elongation stress of the concrete molded body is further improved, and the impact absorption energy is significantly increased. As described above, by increasing the elongation of the concrete reinforcing fiber, a concrete reinforcing fiber capable of improving the bending strength and the compressive strength, particularly the impact strength, of the concrete molded body could be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI D06M 13/00 D06M 13/00

Claims (8)

[Claims] A concrete reinforcing fiber containing a high elongation fiber (A) having a single yarn elongation of 500% or more. 2. A high elongation fiber (A) having a single yarn elongation of 500% or more is from 30 to 100% by weight and a high strength fiber (B) having a single yarn strength of 5 g / d or more is from 0 to 70% by weight. A fiber for reinforcing concrete. 3. The concrete reinforcing fiber according to claim 1, wherein the high elongation fiber (A) has a single yarn elongation of 1000% or more. 4. The concrete reinforcing fiber according to claim 2, wherein the high-strength fiber (B) has a single-yarn strength of 7 g / d or more. 5. High elongation fiber (A) or high strength fiber (B)
Is a polyolefin fiber, The fiber for concrete reinforcement according to any one of claims 1 to 4. 6. High elongation fiber (A) or high strength fiber (B)
A metal salt of a higher fatty acid, a metal salt of a higher alcohol sulfate, a metal salt of an alkylbenzenesulfonic acid, a metal salt of an alkylbenzenenaphthalenesulfonic acid,
The high-strength fiber (A) or the high-strength fiber (A) has at least one surfactant selected from the group consisting of a metal salt of paraffinsulfonic acid, an alkylamine salt and an alkylammonium salt and having an alkyl group having 8 to 22 carbon atoms. The amount of 0.1 to 10% by weight based on the weight of the elongation fiber (B) is applied.
The fiber for reinforcing concrete according to any one of the above. 7. The concrete reinforcing fiber according to claim 6, wherein said metal salt is at least one kind of alkali metal salt selected from Na, Li and K. 8. A concrete molded article molded using the fiber for reinforcing concrete according to any one of claims 1 to 7.