JPS5814288B2 - Manufacturing method of fiber reinforced concrete laminated pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a fiber-reinforced concrete pipe using metal fibers and non-metal fibers in addition to reinforcing bars as concrete reinforcing materials.

In general, concrete pipes are divided into two types: those reinforced with reinforcing bars, asbestos, metal fibers, etc., and those that are not reinforced at all, such as unreinforced concrete IJ pipes. It is used for different purposes.

Among them, the types of reinforced concrete pipes are:
(I) Reinforced concrete pipe manufactured by pouring concrete into a formwork containing reinforcing bars and compacting it using a vibrator, (If) Concrete is poured into a formwork containing reinforcing bars and compacted by centrifugal force. There are reinforced concrete pipes manufactured while compacting (concrete is poured into a formwork containing button reinforcing bars, and reinforced concrete pipes are manufactured while compacting by rolling the concrete surface using rolls.

However, all of these conventional reinforced concrete pipes have the drawbacks of being heavy, having low cracking strength, and insufficient wear resistance.

As a method to solve these drawbacks, concrete pipes have been developed in which metal fibers such as steel fibers are mixed into concrete in addition to reinforcing bars.

This type of concrete pipe is manufactured by mixing metal fibers such as steel fibers into concrete and compacting the concrete using centrifugal force, and has better wear resistance and strength than existing reinforced concrete pipes. It has the effect of being

However, this concrete pipe mixed with metal fibers has caused an alarming problem in that the metal fibers in the concrete are rusted and rust is generated on the inner and outer surfaces of the pipe.

In particular, rust occurring on the inner surface of the pipe is undesirable and poses major restrictions on the uses of concrete pipes.

The object of the present invention is to solve the above-described conventional rust problem and to propose a method for manufacturing a concrete pipe that is lightweight and has high strength and is superior in abrasion resistance compared to existing concrete pipes.

This invention is a method for manufacturing a concrete laminated pipe whose main body is composed of two layers: a layer mixed with metal fibers such as steel fibers and a layer mixed with non-metallic fibers such as carbon fibers, and the metal fibers and non-metallic fibers are mixed into concrete or mortar. The concrete mixed with metal fibers is first poured into the formwork and compacted by centrifugal force, vibration, roll compaction, etc., and then the concrete mixed with non-metal fibers is poured into the formwork. By compacting using the same method, a metal fiber mixed layer is formed on the outer surface of the tube, and a non-metal fiber mixed layer is formed on the inner surface of the tube.

The metal fibers in this invention include ordinary steel, stainless steel,
Alternatively, the material is not particularly limited as long as the material is metal, such as steel fibers subjected to rust prevention treatment.

Further, the non-metallic fibers may be carbon fibers, glass fibers, asbestos, rock wool, etc., which have the same reinforcing effect as metal fibers.

The metal fibers and the non-metal fibers should have an elastic modulus ratio and a specific gravity ratio of 2 to 6, and both fibers should be placed in concrete or mortar so that the volume ratio is 0.05 to 6. shall be mixed separately.

The reason why the elastic modulus ratio and specific gravity ratio of the metal fibers and non-metal fibers are limited to 2 to 6 is as follows.

When the elastic modulus ratio of metal fibers and non-metallic fibers is less than 2, it is effective in improving crack strength, but toughness and deformability become poor. No reinforcement effect on strength can be expected.

Further, the specific gravity pA of the steel fiber is 7.87, the specific gravity pB of carbon fiber is 1.4 to 1.8, and the pB of glass fiber is 2.5.
Since the pB of asbestos is 2.4 to 3.4, p
A/pB was also limited to 2-6.

Further, the volume mixing ratio of the metal fibers and non-metal fibers is set to 0.
The reason for limiting it to 0.05 to 6 was determined from the mixing ratio so that the reinforcing effects of both fibers would be equivalent; below 0.05, the improvement effect of metal fibers on cracking strength, tensile strength, and bending strength will be almost gone. If the value is 6 or more, the effect of improving cracking strength, tensile strength, and bending strength due to non-metallic fibers cannot be expected. It becomes.

The reason why the metal fiber mixed layer was laminated on the outer surface side and the non-metal fiber mixed layer was laminated on the inner surface side is as follows.

In other words, when a metal fiber mixed layer is laminated on the inner surface of the tube,
Water flowing in pipes, and other. There is a risk that the metal fibers will rust due to liquids, expand in volume, and cause cracks in the matrix.

Therefore, the inner surface of the tube was constructed with a layer mixed with non-metallic fibers that would not rust even if it came into contact with water or other liquids.

Note that if water or liquid is not flowing, the laminated structure may be reversed.

The laminated concrete pipe manufactured by the method of this invention has a layer mixed with non-metallic fibers on the inner surface of the pipe and a layer mixed with metal fibers on the outer surface of the pipe, so rust will not occur due to water or other liquids flowing on the inner surface of the pipe. Moreover, since the non-metallic fibers themselves have high wear resistance and can provide the same reinforcing effect as metal fibers, it is expected that the strength of the pipe itself will increase and the wall thickness will be reduced.

Further, when reinforcing with iron/reinforcement, the amount of iron used can be reduced.

Next, one embodiment of the present invention will be described based on the drawings.

Here, a method of forming while compacting by centrifugal force will be explained as an example.

Prior to molding, metal fibers a having an elastic modulus ratio and specific gravity ratio of 2 to 6 and non-metal fibers b are mixed at a volume mixing ratio of 0.05 to 6.
The metal fibers a and non-metal fibers b are separately kneaded together with matrix-forming materials such as cement, aggregate, water, and admixtures so that the fibers are in the range of 6.

First, concrete and mortar mixed with metal fibers a are poured into the formwork 1 which is being rotated in the circumferential direction on the rotary support roller 2, and the wall thickness is adjusted to the circumferential direction while applying centrifugal force. When the mixture becomes uniform, concrete and mortar mixed with non-metallic fibers B are added to form a metal fiber-mixed layer A on the outer surface of the tube and a non-metallic fiber-mixed layer B on the inner surface of the tube.

At this time, since each fiber is two-dimensionally dispersed in the circumferential direction and the tube axis direction, the orientation is advantageous for bending or hoop tension that occurs in the tube due to loads from the inner and outer surfaces after curing.

In addition, in order to resist ring bending of the tube, it is sufficient to reinforce the inner and outer surfaces of the tube, so it is often not necessary to mix fibers in the center of the tube wall thickness. As shown in the figure, concrete and mortar mixed with metal fiber a, normal concrete and mortar mixed with reinforcing fibers, and concrete and mortar mixed with non-metallic fibers are sequentially poured into formwork 1. However, it is also possible to form a metal fiber mixed layer A on the outer surface of the tube, a non-metal fiber mixed layer B on the inner surface of the tube, and a plain concrete layer or plain mortar layer C between the fiber mixed layers A and B.

In addition, when manufacturing reinforced concrete pipes, Figure 1,
As shown in FIG. 2, reinforcing reinforcing bars 3 are inserted into the formwork 1 in advance, and fiber-mixed concrete and mortar are poured into the formwork 1.

As described above, according to the present invention, it is possible to manufacture a concrete pipe in which a layer of metal fibers is laminated on the outer surface of the pipe and a layer of non-metallic fibers is layered on the inner surface of the pipe. It is possible to provide concrete pipes that can be used in a wide range of applications, including general, agricultural, and marine structures.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view showing one embodiment of the present invention, and Fig. 2 is a longitudinal sectional front view showing another embodiment of the same.
...Formwork, 2...Support roller, 3...Reinforcement bar, a...Metal fiber, b...Non-metal fiber, A...Metal fiber mixed layer, B
... Non-metallic fiber mixed layer, C... Plain concrete layer or plain mortar layer.

Claims (1)

[Claims] 1 Metal fibers and non-metal fibers with an elastic modulus ratio and specific gravity ratio of 2 to 6 are used as reinforcing materials, and the volume mixing ratio of the metal fibers and non-metal fibers is in the range of 0.05 to 6. Concrete mixed with metal fibers and concrete mixed with non-metal fibers are mixed separately into the formwork,
A method for manufacturing a fiber-reinforced concrete laminated pipe, which comprises laminating a metal fiber mixed layer on the outer surface of the pipe and a non-metal fiber mixed layer on the inner surface of the pipe.