KR100932108B1 - Polyamide Fiber for Concrete Reinforcement - Google Patents

Abstract

The present invention relates to a polyamide fiber for concrete reinforcement, characterized in that a coating liquid containing an ester lubricant and a surfactant is coated on the fiber surface.

The present invention is coated with a coating liquid containing a lubricant and a surfactant on the fiber surface is excellent in dispersibility and adhesion to concrete in concrete.

Reinforcement, concrete, reinforcing fiber, polyamide, dispersibility, adhesion, coating solution.

Description

Polyamide fiber for reinforcing concrete

The present invention relates to a polyamide fiber for concrete reinforcement, and more specifically, to improve the crack resistance, tensile strength and compressive strength of the concrete by excellent dispersibility in the concrete, adhesion to the concrete and mechanical properties It relates to a polyamide fiber for reinforcement.

Cement hardener of concrete or mortar (hereinafter abbreviated as "concrete") is widely used as an economical construction material, but has a weak point in tensile strength and toughness.

Reinforcing bars have been used as a reinforcing material for improving the toughness of concrete for more than 100 years, and recently, steel system reinforcing materials such as steel plates, pipe steel fibers, and reinforcing bars are widely used instead of reinforcing bars.

Steel fiber, such as reinforcing bar, has a thickness of 0.5 mm and a length of 30 mm, and has good adhesion to concrete and high breaking strength compared to conventional reinforcing bars. This has the advantage of easy, but when used in the construction site, such as a tunnel in which a large amount of moisture, steel fibers are easily corroded, expensive, high specific gravity, there is a problem in the dispersibility in concrete, increasing the load of the concrete.

In order to solve the conventional problems as described above, in recent years, the use of synthetic fibers instead of steel reinforcing materials such as steel fibers as a concrete reinforcing material, such as US Patent No. 5,749,961 and Taiwan Patent Publication No. 2003-47669 Is being studied.

Specifically, synthetic fibers have a smaller specific gravity than steel fibers, and are excellent in corrosion resistance, but may also reinforce concrete crack resistance, tensile strength, and compressive strength than steel fibers.

However, it is known that synthetic fibers do not improve basic structural performances such as flexural strength and flexural performance of concrete, but express only the effect of preventing cracking of concrete.

When synthetic fiber is intended to improve the basic structural performance of concrete, the amount of synthetic fiber should be increased.However, if the amount is increased, it becomes difficult to disperse in concrete, resulting in deterioration of properties such as compressive strength and flexural strength of concrete. Degrades.

Meanwhile, some methods of using synthetic fibers having high strength, such as carbon fibers, aramid fibers, and high-strength polyolefin fibers, have been carried out as concrete reinforcing materials. There was a problem that was.

Therefore, until recently, although the basic structural performance of concrete is not improved, polypropylene fiber, which is inexpensive and effective in preventing cracking of concrete, has been most widely used as a reinforcing material of concrete.

However, polypropylene fiber has good tensile strength of the fiber itself, but due to its hydrophobicity, adhesion property with concrete is poor, and thus the tensile strength of the fiber itself is not sufficiently exerted, thereby improving crack resistance, tensile strength and compressive strength of concrete. There was a problem that the effect was greatly lacking.

As another conventional technique, Japanese Laid-Open Patent Publication No. 2002-137942 proposes a polyamide fiber having a release cross section as a concrete reinforcing material in order to improve the problems caused when using polypropylene fiber as a reinforcing material.

However, since polyamide fiber is more hydrophilic than polypropylene fiber, it has excellent adhesion with concrete, but has low strength and abrasion resistance of the fiber itself, and lacks dispersibility in concrete, resulting in crack resistance, tensile strength and compressive strength of concrete. There was a problem of lack of effect to improve.

In order to solve the above problems, the present invention has excellent dispersibility in concrete and adhesion to concrete, and has excellent strength and abrasion resistance of the fiber itself, thereby greatly improving crack resistance, tensile strength and compressive strength of concrete. To provide a polyamide fiber for concrete reinforcement that can be.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, the polyamide fiber for concrete reinforcement according to the present invention is characterized in that the coating liquid containing an ester-based lubricant and a surfactant is coated on the fiber surface as shown in FIG. 1.

1 is a schematic cross-sectional view of a polyamide fiber for concrete reinforcement according to the present invention.

The present invention is coated with the coating liquid (C) on the surface of the fiber (F) is greatly improved dispersibility in the concrete and adhesion to the concrete.

The coating amount of the coating solution is preferably 0.5 to 3% by weight based on the total weight of the polyamide fiber, and when out of the range, the effect of improving the dispersibility and adhesion may be reduced.

However, in the present invention, the coating amount of the coating liquid is not particularly limited.

As a preferred example, the coating solution may be composed of 40 to 50% by weight of polyhydric alcohol ester lubricant, 30 to 40% by weight of nonionic surfactant, and 10 to 30% by weight of antistatic agent.

In addition, the polyamide fiber for concrete reinforcement according to the present invention has a relative viscosity (RV) of 2.9 or more, more preferably 3.2 or more, the strength measured under the following measurement conditions is 7.5g / d or more, elongation 50 ~ 120 It is preferable that it is%.

Elongation Measurement Condition

The polyamide fiber for concrete reinforcement was held in a universal fiber tensile tester with a gauge length of 5 mm, and then 20 times of strength and elongation were measured at a tension weight of 300 mg and a head speed of 50 mm / min. It is set as these average values.

If the relative viscosity (RV) is lower than the above range, the strength and abrasion resistance of the fiber itself is lowered, and if the strength and elongation of the fiber itself is outside the above range, the effect of improving the crack resistance of the concrete is weakened.

Moreover, it is preferable that the polyamide fiber for concrete reinforcement which concerns on this invention is 12-25 mm in length, and is 4-10 denier in fineness.

When the length is less than 12 mm, the area where the concrete and the fiber contact each other is narrowed, so that the effect of improving the tensile strength and the compressive strength of the concrete may be deteriorated. The entanglement may occur and the concrete properties may be lowered.

When the fineness is less than 4 denier, there is an advantage that the surface area of the fiber is increased to increase the contact area with the concrete, but the strength of the fiber itself may be lowered and the dispersibility of the fiber in the concrete may be reduced.

If the fineness exceeds 10 denier, the number of fibers per unit area of concrete decreases, which creates the risk of forming relatively weak areas in concrete.

In addition, the present invention further improves various physical properties of concrete by providing alkali resistance, hydrophilicity, vibration reduction resistance, and the like, which are inherent in polyamide fibers.

As for the polyamide fiber for concrete reinforcement according to the present invention, it is suitable to use 0.25 to 1 kg per 1 m 3 of concrete.

If less than 0.25 kg per 1 m 3 of concrete, the concrete reinforcing effect is lowered. If it is used more than 1 kg, the dispersibility of the fibers in the concrete is lowered, thereby reducing the tensile strength and slump of the concrete.

In the present invention, the fiber itself is hydrophilic and at the same time a coating liquid of an ester lubricant and a surfactant is coated on the fiber surface, so that the fiber is excellent in dispersibility in concrete and excellent in adhesion to concrete.

In addition, the present invention is excellent in the elongation and wear resistance of the fiber itself.

Therefore, the present invention can greatly improve the crack resistance, tensile strength and compressive strength of concrete.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the scope of the present invention is not limited to the following Examples.

Example  One

50% by weight of polyalcohol ester-based lubricant, nonionic, as a reinforcing material when preparing concrete having a unit area of 1㎥ by mixing 162kg water, 330kg cement, 868kg sand and 964kg aggregate. 0.6 kg of polyamide 6 fibers coated with 1 wt% of the total fiber weight of the coating liquid consisting of 40 wt% of the surfactant and 10 wt% of the antistatic agent were added.

The polyamide 6 fiber has a relative viscosity (RV) of 3.2, a length of 19 m, a fineness of 4 denier, and a gauge length of 5 mm, the strength measured by the above-described measuring method is 7.9 g / d, and the elongation is 70%. to be.

The results of evaluating various physical properties of the concrete produced as described above are shown in Table 2.

Example 2-Example 3

Concrete was prepared in the same process and conditions as in Example 1 except that the addition amount of polyamide 6 fiber, which is a concrete reinforcing material, and the length, fineness, strength, and elongation of the polyamide fiber were changed as shown in Table 1.

The results of evaluating various properties of the manufactured concrete are shown in Table 2.

Manufacture conditions division Addition amount (㎏ / ㎥) Length (mm) Fineness (denier) Strength (g / d) Elongation (%) Example 1 0.6 19 4 7.8 80 Example 2 0.3 19 4 7.8 80 Example 3 0.9 19 8 8.1 60

Comparative Example  One

Concrete was prepared under the same conditions as in Example 1 except that no polyamide 6 fiber of Example 1 was added as a reinforcing material in concrete production.

The results of evaluating various properties of the manufactured concrete are shown in Table 2.

Comparative Example  2

Concrete was prepared under the same conditions as in Example 1 except that 0.9 kg of the polypropylene fiber, which is not coated with the coating solution of Example 1, was added to the surface of the fiber as a reinforcing material.

The results of evaluating various properties of the manufactured concrete are shown in Table 2.

Comparative Example  3

When the concrete having a unit area of 1 m 3 was prepared by combining 162 kg of water, 330 kg of cement, 868 kg of sand, and 964 kg of aggregate, the coating solution of Example 1 was not coated on the surface as a reinforcing material. 0.6 kg of normal polyamide 6 fibers having a relative viscosity (RV) of 2.8, a length of 19 mm and a fineness of 6 denier were added.

The results of evaluating various physical properties of the concrete produced as described above are shown in Table 2.

Concrete property evaluation result division Example Comparative Example One 2 3 One 2 3 Slump (cm) 18.0 18.5 18.0 18.5 18.0 18.0 Air content rate (%) 4.9 4.7 4.5 4.8 4.7 4.9 Compressive strength (MPa) 15 hours 4.13 3.66 2.65 4.37 4.07 4.06 18 hours 6.13 6.59 5.17 6.13 5.37 6.03 1 day 12.2 11.9 10.3 11.2 8.6 11.5 3 days 27.1 28.4 25.5 24.9 24.1 25.1 7 days 33.3 34.3 32.1 32.7 30.1 31.1 Tensile strength (MPa) 1 day 1.49 1.58 1.48 1.38 1.15 1.35 3 days 2.82 2.60 2.75 2.58 2.74 2.55 7 days 3.23 3.14 3.30 2.86 2.81 2.90 Dispersibility ◎ ○ ◎ - ○ ○ Crack resistance Crack Initiation Width (mm) 0.05 or less 0.05 or less 0 (no crack) 0.07 0.07 0.06 Total crack length (cm) 5 53 0 (no crack) 104 114 82

Various physical properties in the present invention were evaluated by the following method.

Slump

Measured by the KS F 2402 method.

Air Content (%)

Measured by KS F 2421 method.

Compressive strength MPa )

It is measured by the method of KS F 2405.

·The tensile strength( MPa )

Measured by KS F 2423 method.

Dispersibility

In accordance with the test method of JCI-SF 7, the concrete mixture of unit area is washed again with water, filtered to collect reinforcing fibers contained therein, and dried to weigh. When the weight of the reinforcing fiber obtained as described above is within ± 10% of the input amount, it was divided into ◎, ○ within ± 20%, and Ⅹ when exceeding ± 20%.

Crack resistance

The cracking resistance is to be placed in a 1m × 1m × 10cm formwork with the restraining reinforcing bars 5cm in height and 10cm smaller in width and length than the formwork. Laboratory average temperature is 30 ℃. The average humidity was measured at 35% after one week of curing. The crack resistance was expressed as the total crack length by the sum of the average crack width and the total crack length in the cracked area.

1 is a schematic cross-sectional view of a polyamide fiber for concrete reinforcement according to the present invention.

* Code description of the main parts of the drawings

F: Nylon fiber C: Coating layer of coating liquid

Claims (8)

A coating liquid composed of 40-50 wt% of a polyhydric alcohol ester lubricant, 30-40 wt% of a nonionic surfactant, and 10-30 wt% of an antistatic agent is coated on the surface of the fiber, and has a fineness of 4-10 denier. Polyamide fiber for concrete reinforcement. The polyamide fiber for concrete reinforcement according to claim 1, wherein the coating amount of the coating solution is 0.5 to 3% by weight based on the total weight of the polyamide fiber. delete The polyamide fiber for concrete reinforcement of claim 1, wherein the polyamide fiber has a relative viscosity (RV) of 2.9 or more. The polyamide fiber for concrete reinforcement according to claim 1, wherein the polyamide fiber has a strength of 7.5 g / d or more measured by a gauge length of 5 mm. The polyamide fiber for concrete reinforcement according to claim 1, wherein the polyamide fiber has an elongation of 50 to 120% as measured by a gauge length of 5 mm. The polyamide fiber for concrete reinforcement according to claim 1, wherein the polyamide fiber has a length of 12 to 25 mm. delete

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