JPS6258886B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for dispersing and mixing carbon fibers into raw materials such as concrete and mortar. The aim is to make it easy to perform manual construction and to make carbon fiber-containing concrete and mortar universally applicable to construction and civil engineering fields.

In recent years, research and development of cement-based composite materials has been actively conducted as a way to improve performance such as bending and tensile strength, impact resistance, and cracking resistance, which are considered to be shortcomings of concrete and mortar.As a result, alkali-resistant glass fiber , attempts have been made to incorporate steel fibers, and this has already been put to practical use in many fields. However, it is a well-established theory that these fibers are thought to have drawbacks in heat resistance, chemical resistance, rust generation, and dispersibility.

Carbon fiber, which is said to be stronger than steel and lighter than aluminum, has appeared in recent years, and although it is a high-performance material that compensates for the drawbacks of the above fibers, it is also expensive, and its uses are limited to sports equipment, heat-resistant materials, etc. It was limited to some. However, recently, the manufacturing and development technology for carbon fiber has progressed rapidly and the possibility of supplying it at a low price has emerged, so it is becoming easier to use it as a cement-based composite material.

In order to use carbon fiber as a cement-based composite material, short carbon fibers are used, and the practical allowable length of the fibers is considered to be about 3 to 30 m/m.
The diameter of the current single fibers is 8 to 18 microns, and the specific gravity is
1.2 to 1.9, it has the property of coagulating like flocs and forming small lumps, and in this state, it can be mixed with cement, aggregate, etc. in a dry state or with water added using a conventional concrete or mortar mixer. Even in a wet state, the fibers form small ball-shaped lumps, and it is extremely difficult to disperse them into single fibers. Currently, the only practical method is to use a special high-performance concrete mixer to disperse cement, aggregate, short carbon fibers, dispersant, water reducer, and water simultaneously using a wet method and special technology. However, at present, even with this method, it is not possible to disperse fibers with a certain fiber length, which is considered to be the most practical. There is also a method in which a mixture of wood wool, glass fiber, and fiber cement is passed in a dry state between rolls provided with protrusions that rotate at the same peripheral speed, but in this method, since the roller peripheral speeds are the same, the mixture is not entangled. It is not possible to loosen the aggregated flocculent short carbon fibers into single fibers.

The present invention involves making short carbon fiber-containing cement or premix mortar in which monofilament short carbon fibers are uniformly dispersed in advance in a factory using a dry method in raw materials for concrete or mortar, and then using a conventional mixer to create cement or premix mortar containing short carbon fibers. This method makes it possible to easily construct high-performance concrete and mortar, and eliminates the drawbacks of conventional methods.

Next, an embodiment of the apparatus for carrying out the method of the present invention shown in the accompanying drawings will be described in detail. 1 and 2 are cylindrical bodies with different diameters, and a large number of needle-like protrusions 3 and 4 made of synthetic resin with appropriate elasticity are evenly provided on the surface.
They are designed to be able to rotate at different circumferential speeds. The rotational speeds of the rotating bodies 1 and 2 can be freely changed to desired rotational speeds using five and six transmissions, respectively.
7, the short carbon fibers in the form of single fibers fall from the opposing parts of the rotors 1 and 2 to the mixer, and on the way to the mixer, raw materials for concrete and mortar placed on the side are scattered and sprayed, and the short carbon fibers are 8 is a nozzle for primary blending of the powder and the powder; 8 is a hopper for small pieces of cotton short carbon fibers 10 arranged above the opposing parts of the pair of rotating bodies 1 and 2; 9 is a small piece of fiber in the hopper; A feeding device 11 for supplying the mass to the intersecting portion of the needle-like protrusions 3 and 4 is a well-known powder stirring device disposed below the rotating bodies 1 and 2.

Next, the method of the present invention will be explained. Hopper 8
A small lump of cotton-like short carbon fibers 10 is fed from the inside by a feeding device 9, and is thrown between the rotating bodies 1 and 2, and is scraped by needle-like protrusions 3 and 4 rotating at different circumferential speeds. It is transported downward while being loosened. At this time, the difference in the circumferential speeds of the rotating bodies 1 and 2 is set in advance by the transmissions 5 and 6 to be most appropriate for the length of the fibers, so that the flocculent short carbon fibers 10 are kept constant. Within the permissible limit of , regardless of the length, the fibers scatter as single fibers 12 and fall into the stirrer 11 below. In this case, the needle-like protrusions 3 and 4 have elasticity, so they rotate smoothly even if they come into contact with each other, but hard needle-like protrusions made of metal or the like may be arranged so that they do not come into contact with each other. An elastic band such as a belt with hard needle-like protrusions installed on the surface may also be used. The shape of the needle may be any of those shown in FIGS. 3 and 4, or may be any other shape. On the other hand, raw materials 13 for concrete and mortar are scattered from the nozzle 7 and dropped into the stirrer 11 while being mixed with the scattered short carbon fibers 12 in the form of single fibers. Next, monofilament short carbon fibers 12, raw materials 13 for concrete or mortar, and other coarse aggregates or additives are evenly mixed in the stirrer 11. Note that the rotating bodies 1 and 2 may have the same diameter and rotate at different rotational speeds, or an endless belt may be used instead of the cylindrical body, or raw materials for concrete or mortar may be directly mixed with an agitator. You may send it.

According to the method of the present invention, small pieces of cotton-like short carbon fibers are moved relative to each other by a pair of movable bodies each having a large number of needle-like protrusions on the surface, and the small pieces of cotton-like short carbon fibers are moved between the two movable bodies. The lumps are fed one after another, and while the needle-like protrusions of the moving body with a slow circumferential speed hold down the small lumps, the needle-like protrusions of the movable body with a fast circumferential speed scrape the small lumps, loosening the small lumps into single fibers, and moving them downward. Short carbon fibers can be dispersed and mixed into raw materials such as concrete and mortar by falling and uniformly mixing with raw materials such as concrete and mortar. Therefore, carbon fiber-containing cement or It is possible to make premix mortar, and it is extremely useful in various fields.

[Brief explanation of the drawing]

FIG. 1 is a cutaway front view of essential parts of an embodiment of an apparatus for carrying out the method of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1. FIGS. 3a and 3b and 4a and 4b are a front view and a side sectional view of the needle-like protrusion, respectively. 1, 2...Rotating body, 3, 4...Acicular projection, 5,
6... Transmission, 7... Powder injection nozzle, 8... Hopper, 9... Feeding device, 10... Cotton short carbon fiber lump, 11... Powder stirring device, 12... Single Fibrous short carbon fibers, 13... Raw materials for concrete, mortar, etc.

Claims (1)

[Claims] 1. A pair of movable bodies each having a large number of needle-like protrusions on the surface are moved relative to each other, and the floc-like short carbon fibers are sequentially fed between the two movable bodies, The needle-like protrusions of the movable body with a slow circumferential speed hold down the small lump, while the needle-like protrusions of the movable body with a fast circumferential speed scrape the small lump, loosening the small lump, forming a single fiber, and falling downward, concrete, A method in which short carbon fibers are dispersed and mixed into raw materials such as concrete and mortar so that they are uniformly mixed with raw materials such as mortar.