Background Art As well known to those skilled in the art, various kinds of fiber additives have been used in concrete or mortar for reinforced thereof. Representative examples of such concrete reinforced fiber additives are steel fiber, glass fiber, nylon, rayon and cotton fibers, polypropylene and polyethylene fibers, carbon fiber, and the like. Here, the steel fiber is often used for the pavement of roads, the polypropylene and polyethylene fibers are used for restricting shrinkage cracks, the carbon fiber is used in various sporting goods, and the glass fiber is used in airplanes, and the like. The carbon and glass fibers are more expensive compared with the other fiber additives, thus they are not used for the pavement of roads.

The above mentioned conventional fiber additives, however, have a disadvantage of high manufacturing cost since they are obtained by processing relatively expensive raw materials. Furthermore, the steel fiber has a difficulty in the handling and transportation thereof and causes several other problems during construction due to its high specific gravity of 7 to 8. The glass fiber and other fibers also have similar problems.

Taking account of the problems as stated above, nowadays, embodiments using waste plastics have been shown.

As one example, Korean Patent Laid-Open No. 1998-087642 discloses a structural material obtained by processing waste plastics and a forming method for the same. Considering the manufacturing process of the disclosed structural material, first, various kinds of waste plastics having different melting points are crushed in a mixed state without going through a sorting process. Then, the waste plastics are melted at an intermediate melting point between the different melting points, and are formed to have a certain shape so that a fiber material consisting of un-melted plastic chips is regularly dispersed in a matrix of molten plastic.

As another example, Korean Patent Laid-Open No. 1998-071969 discloses a plastic composition, which is obtained by mixing 0.5 to 2 weight percent of a silane compound and 0.1 to 1 weight percent of a peroxide compound into mixed waste plastics, and melting a resultant mixture at a temperature of 240 °C to 260 °C.

The silane compound is selected from among amino-silanes, alkoxy-silanes, alkyl- titanate-silanes, or a combination thereof, and the peroxide compound is selected from among aliphatic-peroxides, aromatic-peroxides, or a combination thereof.

Such utilization of waste plastics, however, has not been applied commercially yet at industrial sites, and furthermore, there still exists a need for a method of mixing waste plastics into a concrete composition for the recycling of the waste plastics as industrial refuse.

Disclosure of the Invention Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a cutting apparatus for a fiber reinforced material made from a polyethylene terephtahlate (PET) material obtained by processing waste plastics such as PET bottles, and a composition containing the fiber reinforced material, in order to recycle the waste plastics conforming to the use purposes of construction materials.

Currently, there has been widely used in the field of construction a green slope soil nail reinforcing method, wherein non-hardened fluid mortar is injected into a constructional fabric form by means of a high pressure pump, and the like, thereby forming a concrete mat for use in the repair of scoured regions on slopes, and for preventing corrosion of banks, and protecting foundations of various structures. It is another object of the present invention to complement weak points of mortar or plain concrete by charging a recycled plastic material, which takes the form of cut pieces having constant shapes, into the mortar for reinforced thereof, or in case of construction of a concrete structure, by adding the recycled plastic material into in-situ plain concrete or injecting the recycled plastic material along with shotcrete in a mixed state in order to achieve a steel reinforced effect, thereby achieving an increase in tensile strength, toughness, wear-resistance, shock- resistance, restriction of crack expansion of the mortar or plain concrete, and an improvement in rigidity against bending, compression and splitting thereof.

It is yet another object of the present invention to substitute eco-friendly waste plastics for existing common fiber reinforced materials.

In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of a cutting apparatus for use in a rolled fiber reinforced material, the fiber reinforced material being manufactured by performing a crushing process for crushing a polyethylene terephtahlate (PET) material obtained by processing collected waste plastics such as PET bottles, and then successively performing a mixing process, compression molding process, and dry curing process, the apparatus comprising: a main roller, around which the rolled fiber reinforced material is wound, the main roller having a first motor mounted at one side thereof; a cutting blade for primarily cutting the rolled fiber reinforced material released from the main roller; a lower end belt conveyor driven by a third motor about a pair of first transfer rollers; an upper end belt conveyor driven about a pair of second transfer rollers; and a slicing saw blade located between the upper end belt conveyor and the lower end belt conveyor, the slicing saw blade being driven by a second motor.

In accordance with another aspect of the present invention, there is provided a cutting apparatus for use in a linear fiber reinforced material, the fiber reinforced material being manufactured by performing a crushing process for crushing a polyethylene terephtahlate (PET) material obtained by processing collected waste plastics such as PET bottles, and then successively performing a mixing process, compression molding process, and dry curing process, the apparatus comprising: a main roller, around which the linear fiber reinforced material is wound; first, second, third and forth rollers, along these rollers the linear fiber reinforced material being moved when placed thereon; a water vessel, in which water is received and the second roller and third roller are seated; a compression roller for compressing the linear fiber reinforced material; a forming roller for forming the compressed linear fiber reinforced material to have a certain shape; and a cutting blade for cutting the formed linear fiber reinforced material.

In accordance with yet another aspect of the present invention, there is provided an in-situ mortar composition comprising: 70 to 75 weight parts of cement; 1 to 10 weight parts of an admixture; and 0.1 to 1.5 weight parts of a fiber reinforced material, based on the total weight parts of the composition, wherein the fiber reinforced material is made from a polyethylene terephtahlate (PET) material obtained by processing waste plastics such as PET bottles, and is cut into pieces having a thickness of 0.5 to 2.0 millimeters and a length of 1 to 8 centimeters, the fiber reinforced material pieces being mixed into mortar, concrete, or shotcrete for reinforced of a plain concrete structure or steel reinforced structure.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view schematically illustrating the structure of a cutting apparatus for use in a rolled fiber reinforced material in accordance with the present invention; Fig. 2 is a sectional view schematically illustrating the structure of the cutting apparatus shown in Fig. 1; Fig. 3 is a sectional view schematically illustrating the structure of a cutting apparatus for use in a linear fiber reinforced material in accordance with the present invention; Fig. 4 is a perspective view schematically illustrating the structure of the cutting apparatus shown in Fig. 3; and Fig. 5 is sectional view illustrating various sectional shapes of fiber reinforced material pieces produced by making use of the cutting apparatus in accordance with the present invention.

Best Mode for Carrying Out the Invention The present invention provides a fiber reinforced material, which is intended to be mixed into mortar or concrete so as to increase rigidity and toughness thereof. Such touglmess is essential property of a structural material, and the use of the fiber reinforced material increases toughness of the structural material by up to more than fifteen times. Conventionally, even in case of general reinforced concrete, it experiences corrosion of its constitutional materials including a reinforced material, and invasion of foreign materials due to the generation and expansion of cracks, resulting in breakage around the cracks, and an adverse effect in the durability of the concrete. According to the present invention, however, the fiber reinforced material effectively restricts the generation and expansion of cracks in concrete, thereby continuously maintaining the concrete as a concrete structure, for example, a concrete pavement having a high durability and a high reliability.

The concrete pavement containing the fiber reinforced material as stated above, further, shows an improvement in shock-resistance and wear-resistance against a traffic load applied to the superficial layer thereof. That is, it is noted that, when the fiber reinforced material of the present invention is added to concrete, tensile strength, toughness, wear-resistance, shock-resistance, restriction of crack expansion, and rigidity against bending, compression and splitting of the concrete can be increased.

Figs. 1 and 2 are a perspective view and a sectional view, respectively, which schematically illustrate the structure of a cutting apparatus for use in a rolled fiber reinforced material. The rolled fiber reinforced material is produced by performing a crushing process for crushing a polyethylene terephtahlate (PET) material obtained by processing collected waste plastics such as PET bottles, and then successively performing a mixing process, compression molding process, and dry curing process. The cutting apparatus for the rolled fiber reinforced material comprises a main roller 25, a cutting blade 30, a lower end belt conveyor 40, an upper end belt conveyor 55, and a slicing saw blade 50. The main roller 25 is wound around the circumference thereof with the rolled fiber reinforced material, designated as reference numeral 10, and is provided at its one side with a first motor 20. The cutting blade 30 serves to primarily cut the rolled fiber reinforced material 10 released from the main roller 25. The lower end belt conveyor 40 is driven by a third motor 49 about a pair of first transfer rollers 45, and the upper end belt conveyor 55 is driven about a pair of second transfer rollers 57. The slicing saw blade 50 is located between the upper end belt conveyor 55 and the lower end belt conveyor 40, and is driven by a second motor 47. With the use of the cutting apparatus of the present invention as stated above, the rolled fiber reinforced material 10 is cut into fiber reinforced material pieces 120 having a length of 2 to 8 centimeters. The fiber reinforced material pieces 120 have various sectional shapes as shown in Fig. 5.

Figs. 3 and 4 are a perspective view and a sectional view, respectively, which schematically illustrate the structure of a cutting apparatus for use in a linear fiber reinforced material. The cutting apparatus for the linear fiber reinforced material, designated as reference numeral 60, comprises a main roller 65 around which the linear fiber reinforced material 60 is wound, first, second, third and forth rollers 70,71, 72, and 73, along which the linear fiber reinforced material 60 is moved when placed thereon, a water vessel 80 in which an appropriate amount of water is received and the second roller 71 and third roller 72 are seated, a compression roller 90 for compressing the linear fiber reinforced material 60, a forming roller 100 for forming the compressed linear fiber reinforced material 60 to have a certain shape, and a cutting blade 110 for cutting the formed linear fiber reinforced material 60 to produce fiber reinforced material pieces.

The fiber reinforced material pieces 120 produced by making use of the cutting apparatuse are intended to be mixed into mortar, concrete, or shotcrete for use in construction or public works, thereby producing a fiber reinforced composition. For example, in case of a mortar composition, it consists of 70 to 75 weight parts of cement, 1 to 10 weight parts of an admixture, and 0.1 to 1.5 weight parts of the fiber reinforced material pieces 120, based on the total weight parts of the mortar composition. The fiber reinforced material pieces 120 are made from a polyethylene terephtahlate (PET) material obtained by processing collected waste plastics such as PET bottles, and cutting a resultant mixture to have a thickness of 0.5 to 2.0 millimeters and a length of 1 to 8 centimeters. The mortar composition is intended to be mixed into mortar, concrete, or shotcrete for reinforced of a plain concrete structure or even steel reinforced structure.

Through an indoor experiment performed in a laboratory for comparing and analyzing the compression strength of the composition, it was experimentally verified that the compression strength is variable according to the mixed amount of the fiber reinforced material. The indoor experiment was performed on the basis of the composition which had been aged for twenty-eight days. The composition exhibits the highest compression strength when the volume proportion of the fiber reinforced material made from the recycled plastics is 0.1%, rather than 0%, 0.3%, or 0.5%. The highest value is increased by approximately 32% compared to when the volume proportion of the fiber reinforced material is 0%. The volume proportion of 0% means a non-reinforced composition. Further, the highest value is increased by 20% to 23% above the case in which the volume proportion of the fiber reinforced material is 0.3% or 0.5%.

When analyzing an increase in the compression strength of the composition depending on the kinds of fiber reinforced materials mixed thereto, the compression strength of a steel fiber reinforced composition is approximately 1.45 times as large as that of the fiber reinforced composition using the recycled plastics, and the compression strength of a polypropylene fiber reinforced composition is approximately 1.13 times as large as that of the fiber reinforced composition using the recycled plastics.

Considering the tensile strength, similarly, the fiber reinforced composition using the recycled plastics exhibits the highest tensile strength when the volume proportion of the fiber reinforced material is 0. 1%. When the fiber reinforced material made from the recycled plastics is provided in this amount, the resultant composition exhibits a tensile strength approximately 29% above that of the non- reinforced composition, and 11% to 23% above that of the 0.3% or 0.5% fiber reinforced compositions.

By comparing the tensile strengths of the above mentioned various compositions, it was found that the fiber reinforced composition using the recycled plastics and the polypropylene fiber reinforced composition show relatively similar tensile strengths, and the steel fiber reinforced composition shows a tensile strength increased by approximately 34.6% compared to that of the fiber reinforced composition using the recycled plastics.

Considering analyzed results of bending toughness relation to a fiber reinforced mortar containing the fiber reinforced material made from the recycled plastics, it achieves an increase in an internal tension resistibility and crack resistibility thereof. Such a fiber reinforced mortar further secures ductility, that is, toughness. This means that it secures deformation energy to a large extent, thereby being capable of preventing breakage of a structure due to brittleness. In this case, the toughness can be expressed as an area of a load-defonnation curve (stress-strain diagram). From this area, the toughness can be quantified.

As estimation methods of toughness, there are methods proposed by ACI (American Concrete Institute), ASTM (American Society for Testing & materials), and the like.

As stated above, most of methods for calculating a toughness index define an initial cracking point as a proportional limit point of the load-deformation curve.

In case of concrete, however, it is very difficult to find an accurate proportional limit point since it does not show such a proportional limit point. Further, even in the same materials and same specimens, their proportional limit points may be considerably differential from each other, thus considerably affecting the toughness index to be calculated.

The following Table shows results of bending toughness indexes according to different fiber reinforced materials at different volume proportions, which are calculated by ACI and ASTM methods. As can be seen from the Table, the fiber reinforced material made from the recycled plastics shows a toughness effect having a clearly curved shape.

Table volume proportion of ASTM method ACI fiber reinforced Is Iio 130 method material (%) 0% 5.83 (1. 00) 8.21 (1. 00) 8. 89 (1. 00) 9.56 (1. 00) PET 0.1% 8.31 (1. 43) 13.79 (1. 67) 15.98 (1. 80) 20.36 (2.13) Steel 0. 1% 8.88 (1. 52) 22.55 (2.75) 35.25 (3.97) 36.55 (3.82) PP 0. 1% 8.52 (1. 46) 18.57 (2.26) 29.63 (3. 33) 24.87 (2.60) PET 0.3% 5.34 (0.92) 15.02 (1. 83) 19.73 (2.22) 21.55 (2.25) Steel 0. 3% 8.22 (1. 41) 28. 95 (3.53) 40.12 (4.51) 75.36 (7.88) PP 0.3% 7.53 (1. 29) 20.33 (2.48) 32.75 (3.68) 29.63 (3.10) PET 0.5% 6.12 (1. 05) 9.78 (1. 19) 14.78 (1. 66) 18.01 (1. 88) Steel 0. 5% 7.98 (1. 37) 24. 12 (2.94) 36.53 (4.11) 45.23 (4.73) PP 0. 5% 7.88 (1. 35) 12.38 (1. 51) 20.78 (2.34) 21. 14 (2.21) In the above Table, the results show load-deformation curves obtained when the fiber reinforced material made from the recycled plastics, steel fiber, or polypropylene fiber is mixed into mortar at volume proportions of 0%, 0.1%, 0.3%, and 0.5%, respectively, on the basis of the total weight of the mortar. As can be seen from the experimental results 130 in the ASTM method and the ACI method, differently from an expectation that the fiber reinforced material made from the recycled plastics will show the highest toughness effect when the volume proportion thereof is 0.5%, it shows the highest toughness effect when the volume proportion thereof is 0.3%, and the toughness effect is reduced in order of 0.1% and 0.5%.

The highest value is increased by a maximum of 125% above that of a non- reinforced composition. On the whole, the fiber reinforced material made from the recycled plastics and the polypropylene fiber provide toughness effects having a difference of approximately 20%, and the steel fiber provides a toughness effect far better than that of the others. In conclusion, compared with the non-reinforced composition, the fiber reinforced material made from the recycled plastics shows a clear increase in toughness effect. Although the toughness effect varies according to the shape of the fiber reinforced material, in case of the fiber shape proposed in the above experiment, the volume proportion of the fiber reinforced material achieving the highest toughness effect is in a range of 0. 1% to 0. 3% on the basis of the volume of a specimen.

Industrial Applicability As apparent from the above description, the present invention provides a cutting apparatus for use in a fiber reinforced material made from a polyethylene terephtahlate (PET) material obtained by processing waste plastics, such as PET bottles, which achieves a reduction in manufacturing cost and a mass production of fiber reinforced material pieces.

Further, according to the present invention, as a recycled plastic material taking the form of cut pieces having constant shapes, is charged into mortar for reinforced thereof, or, in case of construction of a concrete structure, as the recycled plastic material is added into in-situ plain concrete or is injected along with shotcrete in a mixed state in order to achieve a steel reinforced effect, it is possible to complement weak points of the mortar or plain concrete, thereby achieving an increase in tensile strength, toughness, wear-resistance, shock-resistance, restriction of crack expansion of the mortar or plain concrete, and an improvement in rigidity against bending, compression and splitting thereof.

Furthermore, by virtue of the fact that waste plastic are utilized so as to produce the recycled plastic material of good quality, it is possible to reduce a cost required for burning or reclamation of the waste plastics as well as to reduce contamination of the environment due to the waste plastics.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.