JPS646005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing tough lightweight cellular concrete bodies.

More specifically, the present invention relates to a method for producing a lightweight cellular concrete body that can be reinforced with alkali-resistant fibers at desired portions of the concrete body when manufacturing a lightweight cellular concrete body provided with reinforcing reinforcing bars.

In recent years, lightweight aerated concrete bodies have become lightweight, fireproof,
It is used in building structures due to its properties such as heat insulation and sound absorption, but on the other hand, it has lower strength and is more fragile than regular concrete, and is susceptible to shocks during product manufacturing, transportation, construction, etc. This has the disadvantage that the product is easily chipped, which reduces the yield of the product and requires time for repair.

These drawbacks are often seen in commonly used lightweight cellular concrete bodies with reinforcing steel, especially in their corners and protrusions. Conventionally, the solution to this problem is to use a foamed cement slurry in which alkali-resistant fibers are dispersed. This method has been proposed, but if the fibers used are long, they may get entangled with the stirring blades of the dispersion mixer, and even if they are well dispersed, the fluidity of the slurry will be significantly reduced. I was naturally restricted.
In addition, the intense contact between fibers and air bubbles for weight reduction,
This causes defoaming of the bubbles, which has also been regarded as one of the problems.

The present invention was made to solve these problems, and will be described in detail below.

Lightweight aerated concrete bodies with reinforcing reinforcing bars usually have parts that are particularly susceptible to external forces such as shocks and other parts that are not, depending on their shape and usage. The method for producing a lightweight cellular concrete body according to the present invention includes casting a foamed cement slurry containing alkali-resistant fibers of a required length on the outer surface of reinforcing reinforcing bars of the lightweight cellular concrete body at least near the portions that are susceptible to external forces. The purpose is to fix it in advance.

The reinforcing reinforcing bars used in the present invention are usually coated with anti-rust coating, and although this anti-rust coating helps to fix the fibers, the present invention is of course not limited to this method; This can also be achieved by fixing using a melt adhesive. Note that the fixation mentioned here does not need to be permanent, and it is sufficient that the fixation is fixed to the reinforcing reinforcing bars at least until the completion of pouring the cement slurry.

Next, the alkali-resistant fibers used in the present invention include alkali-resistant glass fibers, nylon fibers, vinylon fibers, polypropylene fibers, carbon fibers, pulp fibers, asbestos, flooring, stainless steel fibers, etc. When curing in an autoclave, heat-resistant and alkali-resistant glass fiber, carbon fiber,
Pulp fibers, asbestos, stainless steel fibers, etc. are selected.

The thickness and length of these fibers are not particularly limited, but those having a diameter of about 10 μm to 500 μm and a length of at least 7 mm or more, preferably about 20 to 100 mm are used.

We will explain how to fix various types of fibers to reinforcing bars. Because lightweight aerated concrete is naturally lightweight, it carbonates more quickly than regular concrete, and because it is porous, it is easily exposed to air and absorbs water, so internal reinforcing bars are usually treated to prevent rust. is used.

As this rust prevention treatment, a rust preventive coating treatment is generally used. These anti-rust agents include cement slurry made by adding adhesive substances such as rubber latex, resin emulsion, and asphalt emulsion to alkaline powders of Portland cement, quicklime, and slaked lime, or bitumen made by dissolving thermoplastic resin and asphalt in a solvent. The reinforcing reinforcing bars are immersed in a bath containing these rust preventive agents to form a rust preventive coating layer on the surface of each reinforcing bar.
The thickness of this coating layer can be increased by increasing the number of cycles of dipping and solidification, but the various fibers are deposited using a spray gun or the like while the coating tank is in an unsolidified state. In order to prevent the adhesion of fibers from damaging the rust preventive coating layer, it is usually desirable that the fibers adhere to the second and subsequent rust preventive coating layers.

In addition to the method using the above-mentioned spray gun, the method of attaching the fibers may also be a method of partially applying an aqueous suspension of the fibers. Alternatively, after applying a rust preventive agent to the reinforcing reinforcing bars in a frame, it may be placed in a fiber stock tank while unhardened and brought into direct contact with the outer surface of the fibers, so that the rust preventive agent adheres only to the outer surface of the frame and is then solidified.

Furthermore, if the fibers are to be attached to the entire surface of each reinforcing reinforcing bar in a framework, the fibers may be passed through a tank where they are suspended in the air, or the rust preventive may be placed in a water suspension of the fibers after solidification. Another possible method is to soak the reinforcing reinforcing bars so that the fibers can easily adhere to the entire reinforcing bars. By adding, for example, 0.1% by weight of water-soluble polymers such as various cellulose derivatives, polyvinyl alcohol, starch, etc. to the aqueous suspension, the fibers can be smoothly fixed to the reinforcing reinforcing bars.

The fiber length must be appropriately selected depending on the distance between the outer surface of the lightweight cellular concrete body and the reinforcing reinforcing bars, that is, the fog thickness. If the length is too long, the tips of the fibers will protrude from the outer surface of the lightweight cellular concrete body, causing various other problems, which is not preferable.

Also, if it is too short, no reinforcing effect will be produced.

In this way, the reinforcing reinforcing bars to which alkali-resistant fibers are fixed partially or, if necessary, for reinforcing, are installed in a formwork for concrete pouring,
Foamed cement slurry for lightweight concrete is poured in the usual manner. This injection is preferably carried out gradually in consideration of dispersion of the fibers into the slurry.

By employing the manufacturing method described above, there is an effect that fiber reinforcement can be easily carried out without any problem at least in a desired portion of a lightweight concrete body.

The purpose, structure, and effects of the present invention are as described above, but the gist of the present invention is to provide a method for manufacturing a lightweight cellular concrete body with reinforcing reinforcing bars.
The present invention provides a method for producing a lightweight cellular concrete body using a reinforcing reinforcing bar having alkali-resistant fibers fixed to at least a surface portion of the reinforcing bar that is close to a desired portion of the lightweight cellular concrete body.

This will be explained below using examples.

Example A reinforcing reinforcing bar measuring 860 mm (W) x 1760 mm (L) was prepared by fixing the periphery of a 100 mm square weld mesh bar with 50 mm L angle steel using 6 mmφ iron wire, and rubber latex-based cement slurry was prepared. After being immersed in a rust preventive solution bath, the rust preventive coating treatment was carried out twice by repeating air drying, and after the third immersion, a large amount of 40φ polypropylene fiber cut into 50 mm length was applied to each corner of the reinforcing reinforcing bars. After adhering over a length of 200 mm, it was air-dried and fixed. Next, the reinforcing reinforcing bars were fixed in the center of a 900 mm (W) x 1800 mm (L) x 100 mm (H) formwork, and a foamed cement slurry was made of 90 parts by weight of Portland cement, 10 parts by weight of fine silica sand, and 50.5 parts by weight of water. Add a proteolytic foaming agent (trade name: Formics C, manufactured by Hano Kogyo KK) to the mixture.
A foam-containing cement slurry with a slurry specific gravity of 0.890 obtained by introducing 4.6 parts by weight of an aqueous foaming solution (bulk specific gravity 0.05) was slowly cast.

It was left to cure together with the formwork in a humid atmosphere at 40°C for 24 hours, and after curing for two weeks at room temperature and in a humid air condition, it was removed from the mold. This concrete molded body is placed flat on the floor,
A 5 kg eggplant-shaped steel ball was dropped from a height of 2 m above the top of the concrete body, 15 to 20 mm inside the corner, and the state of missing concrete was observed. 4
When I looked at each of the three corners, there were only a few dents and hair cracks, and there was no chipping at the corners.

Comparative Example Molding and testing were carried out under the same conditions as in the example except that no reinforcing fibers were used, but there were frequent chippings and clutches at each corner.

Claims (1)

[Claims] 1. In a method for manufacturing a lightweight cellular concrete body with reinforcing reinforcing bars, a reinforcing bar in which alkali-resistant fibers are fixed to at least the surface portion of the reinforcing bars that is close to a desired part of the lightweight cellular concrete body is used. A method for producing a lightweight aerated concrete body characterized by: