KR100651181B1 - Cement member having reinforcing fibers and composition thereof - Google Patents

Abstract

An object of the present invention is to increase the durability and fire resistance of cement materials. To this end, the present invention provides a cement material comprising the same type of organic fibers different in at least one of length and diameter in any one cement material selected from the group consisting of mortar, concrete and shotcrete. In addition, the present invention is any one cement material composition selected from the group consisting of mortar, concrete and shotcrete, the cement material composition is cement, aggregate particles, at least one dispersant, homogeneous different in at least one of length and diameter The present invention provides a cement material composition including organic fibers and water, and comprising the organic fibers at 0.05 to 5% by volume with respect to the cement material composition.

Mortar, Concrete, Shotcrete, Crack Inhibition, Fire Resistance, Durability, Organic Fiber, Reinforcement Fiber

Description

Cement material comprising reinforcing fiber and composition thereof {CEMENT MEMBER HAVING REINFORCING FIBERS AND COMPOSITION THEREOF}

1 is a schematic diagram of organic fibers having different lengths included in a cement material according to the present invention.

2 is a schematic diagram of organic fibers having different diameters included in the cement material according to the present invention.

3 is a schematic view of organic fibers having different lengths and diameters included in cement materials according to the present invention.

4 is a schematic diagram of a plastic shrinkage crack control test facility of cement material.

5A and 5B are side cross-sectional views and plan views, respectively, for a fire resistance test for testing fire resistance performance of cement materials.

6 is a graph showing the temperature curve used in the fire resistance performance test.

The present invention relates to a cement material, and more particularly, to a cement material and a cement material composition including reinforcing fibers in order to increase durability and fire resistance.

In general, the initial microcracks in cement materials such as mortar, concrete and shotcrete do not have a significant effect on structural performance, but they increase permeability and degrade their durability, and their durability deteriorates. Cause to promote. In addition, when a fire occurs in a building structure, a tunnel, and an underground space where the cement material is used, a cement material having a certain fire resistance is required to minimize the damage caused by the fire.

In this way, the cement material is to suppress the occurrence of cracks to ensure durability performance and at the same time have a sufficient fire resistance in the event of fire. Cement materials with reinforcing fibers are being developed to secure these two performances.

In the related art, US Patent No. 5,749,961 discloses a mixture of organic fibers in concrete having a compressive strength of approximately 90 to 105 MPa, and Korean Patent Publication No. 2003-47069 discloses a step of mixing concrete and organic fibers. Disclosed is a manufacturing method of high-performance concrete for preventing thermal expansion. The organic fibers melt in the event of a fire, forming voids of a certain size inside the concrete, thereby providing a path of heat and gas flow to enhance the fire resistance.

However, since the aforementioned patents and published patents use only one type of organic fiber having the same length and diameter, the effect of suppressing both micro crack and macro crack of the concrete is insufficient, thereby improving durability. There is a drawback to not having a great effect.

And WO 99/28267 discloses ultra high performance concrete containing metal fibers. Metal fiber has a great effect on improving the structural performance of concrete, but it has a bad effect on fire resistance due to high electrical conductivity, and causes a thermal explosion of concrete in the event of fire. In addition, in order to suppress cracking of concrete, a larger amount of metal fibers is required, which leads to an increase in manufacturing cost.

As described above, the conventional cement material has a disadvantage in that durability and fire resistance can not be secured at the same time by using the same type of reinforcing fiber.

Therefore, the present invention is to solve the above problems, an object of the present invention is to provide a reinforcing fiber of the same type, but also to suppress both fine cracks and large cracks to increase the durability and at the same time excellent cement fire resistance In providing ash.

In order to achieve the above object, the present invention is a cement material selected from the group consisting of mortar, concrete and shotcrete, comprising at least one cement material containing the same type of organic fibers different in length and diameter to provide.

In addition, the present invention is any one of the cement material composition selected from the group consisting of mortar, concrete and shotcrete, cement, aggregate particles, at least one dispersant, organic fibers of the same type different in at least one of length and diameter It provides a cement material composition comprising water and water, containing 0.05 to 5% by volume of the organic fibers relative to the cement material composition.

Hereinafter, the present invention will be described in detail.

The present invention relates to cement materials used in construction and civil engineering structures, where the cement materials include mortar, concrete and shotcrete. The cement material according to the present invention includes homogeneous organic fibers of different lengths, homogeneous organic fibers of different diameters, or homogeneous organic fibers of different lengths and diameters.

FIG. 1 schematically shows the organic fibers 1 and 2 having different lengths included in the cement material of the present invention, and FIG. 2 shows the organic fibers 3 and 4 having different diameters included in the cement material of the present invention. Shown schematically. In addition, FIG. 3 schematically shows organic fibers 5 and 6 having different lengths and diameters included in the cement material of the present invention.

Among the organic fibers, organic fibers having a large diameter or length suppress large cracks occurring in cement material, and organic fibers having a small diameter or length suppress fine cracks. As a result, the organic fibers suppress both large cracks and fine cracks of the cement material, thereby increasing the durability of the cement material.

The organic fibers are all organic fibers having a melting point of less than 300 ° C., preferably olefin fibers including polyethylene, polyamide fibers including nylon, polyacrylic fibers, polyester fibers, polypropylene fibers and polyvinyl alcohol fibers. It is made of either fiber.

Since these organic fibers have no thermal conductivity, they have their own fire resistance, and when the cement material rises above 300 ° C. by fire, it melts and forms voids in the cement material. Therefore, heat and gas are moved through the voids to prevent the thermal explosion of the cement material by fire.

At this time, the smaller diameter and length of the organic fiber is advantageous to secure the heat and gas migration path, the effect of preventing the thermal expansion phenomenon, but the effect of securing the resistance to cracking is weak. However, organic fibers with large diameters and lengths are effective in increasing durability by increasing resistance to cracking.

The organic fibers preferably have a diameter of 0.01 to 25 mm and a length of 1 to 100 mm.

As described above, the mortar, concrete, and shotcrete according to the present invention include the same type of organic fibers having different diameters and lengths, and have the effect of securing durability and fire resistance at the same time.

In addition, the cement material composition according to the present invention comprises cement, aggregate particles, at least one dispersant, organic fibers of the same kind and water different in at least one of the diameter and length, the organic fibers are 0.05 To 5% by volume.

If the total content of the organic fibers is less than 0.05% by volume, the effect of the cement material is insufficient in comparison with the cement material without the organic fiber added. If the total content of organic fibers exceeds 5% by volume, the organic fibers are not uniformly dispersed in the cement material, thereby increasing the voids in the cement material, which results in decreased crack suppression performance, strength performance and fire resistance performance. Cause.

In preparing the cement material composition, a simplex lattice design may be used when determining a mixing ratio of organic fibers having at least one of a diameter and a length.

The present invention will be described in more detail with reference to the following examples. However, the Examples are provided to illustrate the present invention and the present invention is not limited to these.

EXAMPLE

Examples 1 to 9, Comparative Examples 1 to 4

Table 1 below shows the optimum mixing ratio of the organic fibers determined using the simplex lattice arrangement method such that the total content of organic fibers having different lengths is 0.35% by volume based on the cement material composition. The organic fibers used at this time are polypropylene fibers, and the lengths are 4 mm, 6 mm, 8 mm, and 12 mm, respectively, and the diameters are the same as 0.09 mm.

Kind of combination Organic fiber mixing rate (%) Length: 4mm Length: 6mm Length: 8mm Length: 12mm A 0.17500 0.17500 - - B 0.17500 - 0.17500 - C 0.17500 - - 0.17500 D - 0.17500 0.17500 - E - 0.17500 - 0.17500 F - - 0.17500 0.17500 G 0.21900 0.04375 0.04375 0.04375 H 0.04375 0.21900 0.04375 0.04375 I 0.04375 0.04375 0.21900 0.04375 J 0.04375 0.04375 0.04375 0.21900 K 0.08750 0.08750 0.08750 0.08750

Table 2 below shows three examples included in the actual cement material composition among the types of the formulations described in Table 1 and considered in order to evaluate the crack control performance and the fire resistance performance of the cement material.

Organic fiber mixing rate (%) Length: 4mm Length: 6mm Length: 8mm Length: 12mm Example 1 0.17500 - 0.17500 - Example 2 0.21900 0.04375 0.04375 0.04375 Example 3 0.08750 0.08750 0.08750 0.08750

Table 3 below shows the optimum mixing ratio of the organic fibers determined using the Simplex lattice arrangement method such that the total content of organic fibers having different diameters is 0.35% by volume based on the cement material composition. The organic fibers used at this time are polypropylene fibers, and the diameters are 0.02 mm, 0.04 mm, 0.06 mm, and 0.09 mm, respectively, and the length is equal to 12 mm.

Kind of combination Organic fiber mixing rate (%) Diameter: 0.02mm Diameter: 0.04mm Diameter: 0.06mm Diameter: 0.09mm A 0.17500 0.17500 - - B 0.17500 - 0.17500 - C 0.17500 - - 0.17500 D - 0.17500 0.17500 - E - 0.17500 - 0.17500 F - - 0.17500 0.17500 G 0.21900 0.04375 0.04375 0.04375 H 0.04375 0.21900 0.04375 0.04375 I 0.04375 0.04375 0.21900 0.04375 J 0.04375 0.04375 0.04375 0.21900 K 0.08750 0.08750 0.08750 0.08750

Table 4 below shows three examples included in the actual cement material composition among the types of the formulations described in Table 3 and considered in order to evaluate the crack control performance and the fire resistance performance of the cement material.

Organic fiber mixing rate (%) Diameter: 0.02mm Diameter: 0.04mm Diameter: 0.06mm Diameter: 0.09mm Example 4 0.17500 - 0.17500 - Example 5 0.21900 0.04375 0.04375 0.04375 Example 6 0.08750 0.08750 0.08750 0.08750

Table 5 shows the optimum mixing ratio of the organic fibers determined using the Simplex lattice arrangement method such that the total content of organic fibers having different diameters and lengths is 0.35% by volume with respect to the cement material composition. Three examples contemplated for evaluation are shown. The organic fiber used at this time is a polypropylene fiber.

Organic fiber mixing rate (%) Length: 4mm Diameter: 0.02mm Length: 6mm Diameter: 0.04mm Length: 8mm Diameter: 0.06mm Length: 12mm Diameter: 0.09mm Example 7 0.17500 - 0.17500 - Example 8 0.21900 0.04375 0.04375 0.04375 Example 9 0.08750 0.08750 0.08750 0.08750

On the other hand, the four comparative examples considered in order to evaluate the crack control performance and fire resistance performance of the cement material is as follows.

In Comparative Example 1, a single shape steel fiber having a length of 30 mm and a diameter of 0.5 mm was included in the volume of 0.7% by volume relative to the concrete and shotcrete composition. In Comparative Example 2, a single-shaped organic fiber (polypropylene fiber) having a length of 19 mm and a diameter of 0.02 mm was included in 0.35% by volume relative to the concrete and shotcrete composition.

In Comparative Example 3, organic fibers having different lengths and diameters were included, but the organic fibers were included 0.04% by volume of the cement material composition. In Comparative Example 4, organic fibers having different lengths and diameters were included, but the organic fibers were included in a volume of 5.6% by volume of the cement material composition. Table 6 below shows the fiber mixing ratios of Comparative Example 3 and Comparative Example 4.

Organic fiber mixing rate (%) Length: 4mm Diameter: 0.02mm Length: 6mm Diameter: 0.04mm Length: 8mm Diameter: 0.06mm Length: 12mm Diameter: 0.09mm Comparative Example 3 0.01 0.01 0.01 0.01 Comparative Example 4 1.4 1.4 1.4 1.4

Table 7 is a composition table of the cement material used for the performance evaluation.

(kg / mm ³ ) water cement Fine aggregate Coarse aggregate High fluidizing agent (% of C) Examples 1-9 211 480 1,110 483 1.35 Comparative Examples 1 to 4

(Plastic shrinkage crack control test)

Plastic shrinkage crack control test was performed to evaluate the durability performance of cement materials. This test follows the test method proposed by Kraai and shows the plastic shrinkage crack control test fixture in FIG. 4.

In FIG. 4, reference numeral 7 denotes a mold, and reference numeral 8 denotes fixing pieces fixed around the mold bottom surface. The mold 7 has a thin plate-like internal volume of 900 × 600 × 150 mm, and each fixing piece 8 has a shape of 13 × 7 × 120 mm. The distance between the centers of the fixing pieces 8 is set to 100 mm.

The cement material having the composition shown in Table 6 was poured into a mold and plastered by reciprocating five times in the longitudinal direction using a trowel. After pouring, the temperature was maintained at 28 ± 2 ° C. and the humidity at 40 ± 3%, and the wind speed was kept constant at 6 m / s using a fan. The conditions were maintained for 24 hours in a constant temperature and humidity room.

In this process, the cement material filled in the mold shrinks with drying over time. As the fixing pieces restrain the cement material shrinking toward the mold center, tensile stress occurs in the cement material.

Table 8 shows the results of measuring the crack width and the crack length generated in the cement material after 24 hours in the constant temperature and humidity chamber, and obtained the crack area by multiplying the crack width and the crack length.

Since cracks in cement materials increase permeability and cause structural destruction, suppressing cracks is a very important factor in improving durability. From the above results, in the embodiments of the present invention in which at least one of the length and the diameter are mixed, the crack control performance is better than that of Comparative Example 1 using a single shape steel fiber and Comparative Example 2 using a single shape organic fiber. It can be seen that it is exercised.

In addition, although the organic fibers having different lengths and diameters were mixed, Comparative Example 3, in which the total content of organic fibers was 0.04% by volume, did not show a sufficient effect to suppress the occurrence of cracking, and the total content of organic fibers having different lengths and diameters was 5.6. In Comparative Example 4, which is% by volume, it can be seen that the crack inhibiting effect is not large because organic fibers are not uniformly dispersed in the cement material and are aggregated in part.

(Fireproof performance experiment)

To evaluate the fire resistance, compressive and flexural strengths were measured after exposing cement specimens to fire.

The fire test was performed using the fire resistance test furnaces shown in FIGS. 5A and 5B, and was performed according to the RABT curve (see FIG. 6), which is a fire curve temperature defined by the Ministry of Transport, Road, and Construction. In FIG. 5A and FIG. 5B, the code | symbol 9 represents a cement material specimen and the code | symbol 10 shows a heating element. The compressive strength test was conducted according to KS F 2405, and the flexural strength test was performed according to JCI SF-4.

Table 9 below shows the results of observing the surface after the cement specimen was exposed to fire, and the compressive and flexural strength test results.

Surface observation Compressive strength (MPa) Flexural strength (MPa) Residual Compressive Strength (%) Residual flexural strength (%) crack Peeling Bomb Example 1 X X X 21.5 2.7 82.2 84.7 Example 2 X X X 21.4 2.8 83.3 83.9 Example 3 X X X 20.7 2.9 82.4 81.3 Example 4 X X X 18.3 2.4 78.2 74.7 Example 5 X X X 19.4 2.3 80.3 73.9 Example 6 X X X 18.7 2.1 79.4 71.3 Example 7 X X X 17.9 2.7 78.7 76.3 Example 8 X X X 19.1 2.9 81.1 75.1 Example 9 X X X 18.3 2.8 79.2 73.1 Comparative Example 1 O O O 21.1 2.1 42.2 41.7 Comparative Example 2 O X X 24.3 1.4 48.5 40.5 Comparative Example 3 O X O 9.7 0.9 40.8 43.7 Comparative Example 4 X X X 9.5 1.6 39.7 41.3

As shown in the table, in Comparative Example 1 containing a single-shaped steel fiber cracking, peeling and thermal phenomena occurred in the specimen after the refractory test. This is because steel fibers are thermally conductive and have little resistance to fire. And most of the compressive and flexural strengths were lost after the fire test.

In Comparative Example 2 in which a single shape of organic fibers were included, thermal expansion and peeling phenomena were hardly generated, but largely occurred in comparison with the embodiments of the present invention. In addition, the compressive and flexural strengths were greatly lost after the fire test, due to the formation of the same sized voids in the specimen as the organic fibers of the same shape melted by the fire.

In addition, in Comparative Example 3 in which organic fibers having different lengths and diameters were mixed with 0.04% by volume, cracking and thermal expansion occurred, and a large decrease in strength after a fire occurred. In Comparative Example 4, in which organic fibers having different lengths and diameters were mixed with 5.6% by volume, the effect of fire resistance was not large due to the excessive amount of organic fibers and the concentration of some organic fibers.

On the other hand, in the embodiments of the present invention in which at least one of the length and the diameter are mixed with each other, no cracking, peeling, and thermal phenomena occurred in the specimen after the fire resistance test, and when the organic fibers were melted by fire, As at least one of the length and diameter formed different pores, the reduction in compressive strength and flexural strength was smaller than in the comparative examples. From the above results, it can be seen that the embodiments of the present invention exhibit better fire resistance than the comparative examples.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to

As described above, the mortar, concrete, and shotcrete according to the present invention include the same type of organic fibers having different lengths and diameters, thereby suppressing both large cracks and fine cracks, thereby increasing durability and improving fire resistance by using organic fibers. Secure. Therefore, mortar, concrete, and shotcrete according to the present invention have the effect of securing durability and fire resistance simultaneously while using the same type of holding fiber.

Claims (7)

In any cement material selected from the group consisting of mortar, concrete and shotcrete, And the cement material comprises mixed organic fibers of any one of the same type of organic fibers having different diameters and the same type of organic fibers having different diameters and lengths. The method of claim 1, Cement material having a melting point of less than 300 ℃ the organic fibers. The method of claim 2, Cement material consisting of any one of the fibers selected from the group consisting of olefin fiber comprising polyethylene, polyamide fiber including nylon, polyacrylic fiber, polyester fiber, polypropylene fiber and polyvinyl alcohol fiber . The method of claim 1, Cement material having a diameter of 0.01 to 25mm, and a length of 1 to 100mm of the organic fibers. In any cement composition selected from the group consisting of mortar, concrete and shotcrete, The cement material composition includes cement, aggregate particles, dispersant, mixed organic fibers of any one of the same kind of organic fibers having different diameters and organic fibers of the same kind having different diameters and lengths, and the organic fibers Cement material composition comprising 0.05 to 5% by volume relative to the cement material composition. The method of claim 5, Cement material composition having a melting point of less than 300 ℃ the organic fibers. The method of claim 5, The cement fiber composition has a diameter of 0.01 to 25mm, and a length of 1 to 100mm.

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