JPS6143316B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to steam-cured lightweight cellular concrete with excellent impact resistance. Steam-cured lightweight aerated concrete (below)
(abbreviated as ALC) is made by mixing silica raw materials such as silica sand and silica stone and calcareous raw materials such as lime and cement in an appropriate proportion with water, and then adding a foaming agent such as aluminum metal powder. It is manufactured by foaming it to a semi-plastic state, then transferring it to an autoclave and curing it with high temperature and high pressure steam. ALC manufactured in this way has a large number of pores and is therefore lighter than water, but it is said to be prone to chipping due to impacts received during the manufacturing process, product transportation, or construction, as well as localized concentrated loads. There are drawbacks. In order to prevent these ALCs used as building materials from chipping, a method has conventionally been proposed in which a fibrous material such as glass fiber is bonded to the surface layer of the ALC using a synthetic resin binder for reinforcement. However, although it is true that impact resistance can be improved by reinforcing these fiber materials, the effect is not expected because the reinforcing material is only fixed to the surface layer. At present, it is not possible to obtain as much impact resistance as possible, and there is a strong desire for something with even better impact resistance. The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional methods and provide an ALC with improved impact resistance.
In order to achieve this object, the present invention adds and mixes carbon fibers with a diameter of 20μ or less and a length of 100mm or less, preferably 3mm or more and 100mm or less, in an amount of 0.1 to 3.0% by weight based on the total solids of the above-mentioned mixture. This is then autoclaved using a standard method to obtain ALC with excellent impact resistance. The outline of the present invention will be explained below. In addition to the carbon fibers used in the present invention, various fibers may be used to mix in the production of the ALC of the present invention. For example, asbestos fiber, glass fiber or alkali-resistant glass fiber, etc.
Fibers with strong stiffness, such as the former type,
In the foaming process of ALC production, the formation of independent spherical cells is inhibited, resulting in a decrease in strength and impact resistance. However, it has fatal drawbacks such as being eluted into alkaline water during the autoclave curing process, both of which are undesirable. Therefore, the fibers used in the production of ALC of the present invention are specified as carbon fibers. There are various types of carbon fibers used in the present invention, such as carbon fibers obtained by firing and carbonizing organic fibers such as polyacrylonitrile, rayon, polyethine, polypropylene, lignin poval, and pituti, or if necessary, further carbon fibers. Graphitized so-called graphite fibers can be used. As mentioned above, the carbon fiber has a diameter of 20
μ or less, with a length of 100 mm or less, preferably 3 to 100 mm, is added and mixed into the slurry in an amount of 0.1 to 3.0% by weight based on the total solids of the raw material mixture. The reason why the diameter of the carbon fiber is set to 20μ or less is that if the diameter is larger than this, the fiber loses its flexibility, which causes excessive stress during foaming and prevents the formation of good bubbles. The above refers to a fiber length of 100 mm or more and an additive amount of 3.0 mm.
If the amount exceeds % by weight, the added fibers will become entangled with each other and form a "marimo" shape, making it difficult to disperse uniformly, causing internal defects and reducing mechanical strength. 3mm or less, the amount added is
This is because if the amount is less than 0.1% by weight, the impact resistance effect will not be noticeable. Calcareous raw materials, which are the main raw material mixtures for ALC, include lime and cement; silica raw materials include silica stone, silica sand, blast furnace slag, and fly ash; foaming agents include aluminum powder and surfactants, etc. There are no particular restrictions as long as it is suitable. For stirring the raw material mixture, commonly used stirrers such as paddle mixers, propeller mixers, pot mixers, etc. can be used. In order to uniformly disperse the carbon fibers, the carbon fibers may be treated with a surfactant beforehand, or a surfactant may be added to the raw material slurry as necessary. Steam curing in an autoclave after foam molding can be carried out under general conditions, for example, using saturated steam at a gauge pressure of 10 Kg/cm ² and a temperature of 180°C. The lightweight cellular concrete of the present invention had a bending strength that has a strong correlation with impact resistance, and its effect was measured, and as shown in the examples, it showed about twice the bending strength of the case without carbon fibers. Examples will be described below. Example 6 parts by weight of quicklime powder, 22 parts by weight of Portland cement, 32 parts by weight of silica powder, 0.05 parts by weight of aluminum powder, 40 parts by weight of water, 0.1 to 3.0% by weight based on the total amount of the solids. After adding and mixing specified carbon fibers to form a slurry, steam-cured lightweight cellular concrete was manufactured according to normal operations. A 4 x 4 x 16 cm test piece was cut out from the obtained product and its bending strength was measured using a Michalies tester instead of the impact resistance test. The results are shown in Table 1.

【table】

【table】

[Table] As is clear from Table 1, the bending strength was significantly improved in all cases except for Experiments Nos. 2 and 3, and Nos. 4 and 5, which were outside the scope of the present invention. However, the fiber length is 100mm
For those with a large amount added, the added fibers became marimo-like. In addition, the bulk specific gravity of the product is 0.48~
0.51, and no obstruction to foaming was observed due to the added fibers.

Claims (1)

[Claims] 1. In steam-cured lightweight cellular concrete whose main raw materials are powdered silica raw materials and calcareous raw materials, carbon fibers with a diameter of 20 μ or less and a length of 100 mm or less are added to the slurry mixture of the raw materials at 0.1% of the total solid content.
Steam-cured lightweight cellular concrete with excellent impact resistance, containing ~3.0% by weight.