JPH10286819A - Method for handling fiber material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent soaring or floating of short fiber in the air by freezing the fiber such as carbon fiber, and conducting handling operation such as measuring, conveying, storing or charging of the fiber of frozen state. SOLUTION: Carbon fiber such as, for example, filament state to be called 'chipped strand' having a length of several mm to several tens mm and a diameter of several μm to several tens μm is to be an object. Freezing adopts a freezing method for freezing, for example, with liquid nitrogen as refrigerant. The method comprises the steps of freezing the carbon fiber of the short fiber (S101), suitably metering the frozen carbon fiber according to a predetermined mixing design (S102), and then charging the metered carbon fiber as remained in the frozen state (S103). At each time of handling, there is no fear of soaring the short fiber in the air. Thus, handling of the short fiber in each operation is facilitated, and effective operation is performed. Hence, an operator can avoid erroneous sucking of the short fiber in his nose or filling of the fiber in his eye.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for handling short fibers mainly used for fiber reinforced concrete.

[0002]

2. Description of the Related Art It is well known that concrete has a very low tensile strength as compared with its compressive strength, and its elongation ability is very poor as compared with steel or the like. Research has been conducted into fiber-reinforced concrete by mixing short fibers, also called chopped strands, into concrete.By combining carbon fibers and aramid fibers, which have excellent tensile strength and elongation capacity, with concrete as a matrix, It is expected that the tensile strength and elongation ability can be improved.

[0003]

However, such short fibers have a length of several mm to several tens mm and a diameter of several μm to
It is in the form of a filament of several tens of μm and extremely lightweight, and is likely to fly into the air when short fibers are dropped at the time of metering or mixing of a mixer, or by natural wind or draft of air by air conditioning.

[0004] For this reason, if there is a problem that the weighing operation or the charging operation cannot be performed smoothly or if there is a possibility that the short fibers floating in the air may be inhaled or caught by eyes, measures for health and hygiene should be taken. There was also a problem that it had to be taken separately.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a method of handling a fiber material capable of preventing short fibers from rising and floating in the air.

[0006]

In order to achieve the above-mentioned object, a method for handling a fiber material according to the present invention comprises the steps of freezing short fibers such as carbon fibers and shortening the frozen state. Handling operations such as measurement, transport, storage, and introduction of fibers are performed.

Further, in the method for handling a fiber material according to the present invention, moisture is imparted to the short fibers before freezing the short fibers.

In the method of handling a fiber material according to the present invention, short fibers such as carbon fibers are frozen in advance, and handling such as weighing, transporting, storing and throwing is performed in the frozen state. This eliminates the risk that the short fibers will fly into the air at the time of weighing or charging the mixer, and facilitates handling in each step.

The method for freezing the short fibers is optional. Specifically, a freezing method using liquid nitrogen as a refrigerant besides ordinary freezing equipment is conceivable. According to the latter method,
Short fibers can be frozen economically with relatively simple equipment and even when the amount of freezing is small. The short fibers include steel fibers, glass fibers, carbon fibers, and synthetic fibers formed of polyethylene, polypropylene, aramid, or the like.

Here, when water is imparted to the short fibers before freezing the short fibers, the short fibers can be reliably frozen irrespective of the water content of the short fibers.
The formation of the frozen layer on the surface of the short fibers prevents the short fibers from becoming entangled with each other, and improves the dispersibility and the mixing ratio in the concrete.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the method for handling a fiber material according to the present invention is applied to a process for producing fiber reinforced concrete will be described below with reference to the accompanying drawings.

FIG. 1 is a flowchart showing a procedure of a method for handling a fiber material according to the present embodiment. As shown in the figure, in the method for handling a fiber material according to the present embodiment, first, carbon fibers which are short fibers are frozen (step 101).

[0013] The carbon fiber is called, for example, a chopped strand and has a length of several mm to several tens mm and a diameter of several μm to
Filaments of about several tens of μm can be targeted.

For freezing the carbon fiber, for example, a freezing method using liquid nitrogen as a refrigerant can be adopted. According to such a method, relatively simple equipment and a small amount of freezing are used. It can also economically freeze carbon fibers.

Next, the frozen carbon fibers are appropriately weighed according to a predetermined blending design (step 102), and thereafter, the measured carbon fibers are put into a mixer in a frozen state (step 103).

This eliminates the risk that the carbon fibers will fly into the air when measuring or charging the mixer, and facilitates the handling of the carbon fibers in each step.

After the carbon fiber is put into the mixer, the carbon fiber is stirred and kneaded together with other concrete materials put into the mixer, and the carbon fiber is dispersed in the fresh concrete.

As described above, according to the method for handling fiber material according to the present embodiment, the carbon fiber is frozen in advance before the weighing or charging is performed. There is no danger of soaring.

Therefore, the handling of the carbon fibers during each operation is facilitated, and the metering and feeding can be performed reliably. Further, it is possible to prevent a situation in which the worker accidentally inhales the carbon fiber or gets into the eyes of the worker.

It is to be noted that although the carbon fiber may be dried before being weighed or charged if the carbon fiber is simply wetted, the handling method according to the present embodiment has an effect of preventing the carbon fiber from flying into the air. It can last for a certain period of time.

In this embodiment, carbon fibers are used as short fibers. However, the present invention is not limited to such materials. Instead of carbon fibers, steel fibers, glass fibers, or polyethylene, polypropylene, or aramid may be used. Synthetic fibers or the like may be used.

Although not particularly mentioned in the above description, it goes without saying that the handling method of the present invention can be applied in a factory or on-site.

Also, in the present embodiment, the time of weighing and the time of charging are assumed as the handling process. Alternatively, for example, a process of temporarily storing the product outdoors or indoors, or a process of transporting the product from a storage location to a mixer truck. May be applied. According to such a configuration, even if the wind blows outdoors, or the airflow is generated in the room due to the opening and closing of the door or the air conditioning, there is no fear that the carbon fibers fly into the air during storage or transportation.

Although not specifically mentioned in the present embodiment, when the water content of the carbon fiber is small, water may be added to the carbon fiber before freezing it.

FIG. 2 is a flowchart showing a method of handling a fiber material according to such a modification. In this modification, as shown in the figure, first, carbon fibers, which are short fibers, are immersed in water (step 111), and then the carbon fibers are frozen (step 101).

Thereafter, similarly to the above-described embodiment, the frozen carbon fibers are appropriately measured according to a predetermined blending design (step 102), and then the measured carbon fibers are put into a mixer in a frozen state. (Step 103). Then, the carbon fiber is stirred and kneaded with the other concrete material put into the mixer, and dispersed in the fresh concrete.

According to the present modification, as in the above-described embodiment, there is no possibility that the carbon fibers will fly into the air at the time of weighing or mixing in the mixer, and the handling of the carbon fibers in each step becomes easy. Irrespective of the degree of water content, this can be reliably frozen, and by forming a frozen layer on the surface of the carbon fiber, entanglement of the carbon fibers is prevented, dispersibility in concrete and There is another effect that the mixing ratio is improved.

[0028]

As described above, according to the method for handling fiber material according to the first aspect of the present invention, there is no fear that short fibers will fly into the air during handling such as weighing, storage, transportation, and charging. This facilitates handling of short fibers during each operation, making it possible to carry out each operation reliably, and prevents workers from accidentally inhaling short fibers or getting in the eyes of workers. Can also be avoided.

According to the fiber material handling method of the present invention according to the second aspect, in addition to the effect of the first aspect, it is ensured that the short fiber is frozen irrespective of the water content. By forming a frozen layer on the surface of the staple fiber, tangling of the staple fiber is prevented, and another effect of improving the dispersibility and mixing ratio in the concrete is exhibited.

[0030]

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for handling a fiber material according to an embodiment.

FIG. 2 is a flowchart showing a method of handling a fiber material according to a modification.

[Explanation of symbols]

 101 freezing step 102 measuring step (handling step) 103 charging step (handling step) 111 moisture applying step

Claims (2)

[Claims] 1. A method of handling a fiber material, comprising freezing short fibers such as carbon fibers and performing handling operations such as weighing, transporting, storing, and throwing the frozen short fibers. 2. The method for handling a fiber material according to claim 1, wherein moisture is imparted to the short fibers before freezing the short fibers.