JPS6257600B2 - - 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 into 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, making it lighter than water, but it is said to be prone to chipping due to shocks and local concentrated loads during the manufacturing process, product transportation, or construction. There are drawbacks. In order to prevent these ALCs used as building materials from chipping, conventional methods have been proposed in which the surface layer of ALC is reinforced by bonding fibrous materials such as glass fibers and synthetic fibers using synthetic resins and inorganic binders. has been done. 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. I didn't get as much as I should have. In addition, attempts have been made to mix asbestos fibers as a reinforcing material into the ALC raw material mixture, but when asbestos fibers are added to the mixed slurry, asbestos fibers have water-retentive properties, they form a ball-like shape and are not evenly distributed. There was a problem of not being dispersed, and asbestos fibers absorbed water over time during the foaming process, which increased the viscosity of the slurry and inhibited foaming, making it difficult to form independent spherical cells. 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 objective, the present invention uses asbestos fibers that have been treated with a water-repellent substance in the raw material formulation of ALC, in proportion to the total solid content of the above-mentioned formulation.
0.1 to 5% by weight is added and mixed, and then autoclaved according to a conventional method to obtain ALC with excellent impact resistance. The outline of the present invention will be explained below. As the asbestos fibers to be mixed in when producing the ALC of the present invention, amphibole asbestos fibers and serpentine asbestos fibers, which are generally called asbestos, can be used. Asbestos fibers are characterized by excellent mechanical performance such as heat resistance, alkali resistance, and tensile strength.
Even when exposed for a long time to alkaline water with a pH of about 13 at ℃, there is almost no change in strength retention. These asbestos fibers are coated with silicone resins, such as dimethyl silicone oil, silicone varnish, phenyl silicone oil, their respective modified products or their respective emulsions or carboxylic acid salts, carboxylic acid soaps, vegetable oil soaps, paraffin and their respective emulsions. In order to attach a general water repellent and, in some cases, sufficiently adhere the water repellent to the asbestos fibers, the raw material is treated with a water repellent using a solvent, an activator, a catalyst, etc., and then dried and baked. It is used by adding it to the slurry in an amount of 0.1 to 5.0% by weight based on the total solids of the formulation. The reason for limiting the amount of asbestos fiber added to the above range is that the amount added is
If the amount is more than 5.0% 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. This is because if the amount is less than % by weight, the impact resistance effect will not be noticeable. Water-repellent treated asbestos fibers can be homogeneously dispersed in the raw material blending slurry by loosening them well and mixing them in. Also, by preventing the fibers from absorbing water during the foaming process, the increase in viscosity of the slurry can be suppressed. It can be expected to form good bubbles. Calcareous raw materials, which are a mixture of the main raw materials for ALC, include lime and cement; silica raw materials include silica stone, silica sand, silica clay, blast furnace slag, and fly ash; foaming agents include aluminum powder, surfactants, etc. There is no particular restriction as long as it is commonly used. For stirring the raw material mixture, commonly used stirrers such as paddle mixers, propeller mixers, turbo mixers, grid mixers, pot mixers, etc. can be used. In order to uniformly disperse the water-repellent asbestos fibers in the raw material slurry, a surfactant is attached to the fibers in advance and added to the raw material mixture, or a surfactant is added to the raw material slurry as necessary. can also be added. 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. Examples will be described below. Example 1 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, and dimethyl silicone oil based on the total amount of the solids. After immersing serpentine-based asbestos fibers (3-10 mm in length) in a solution diluted with xylol at a ratio of 1:9,
After drying and baking at 300°C for 5 minutes, a predetermined proportion of the mixture was added and mixed, and steam-cured lightweight cellular concrete with a specific gravity of 0.5 was produced according to normal operations. Cut a 10 x 15 x 3 cm test piece from the obtained product,
For the impact test, the test piece was placed horizontally at the fulcrum distance.
Fix it at 10cm and place a weight from a height of 13cm in its center.
A 300g egg-shaped steel ball was dropped, and the number of drops was measured until the test piece cracked.
Therefore, the greater the number of drops, the better the impact resistance. Regarding the quality of the bubbles, the ones where the bubbles generated by microscopic observation were non-uniform and had few closed cells were expressed as "failure". Further, as a comparative example, a material to which no asbestos fiber was added was also tested in the same manner. The results are shown in Table 1.

[Table] From the results in Table 1, Test No. 3-6 had better impact resistance and better bubble condition than the comparative example. However, in Test No. 2, in which the addition of asbestos fibers was below the lower limit, the impact resistance was not good;
In No. 7, the added amount of fibers exceeded the upper limit and the fibers were shaped like a potato and were not evenly distributed, making it impossible to obtain satisfactory results. Example 2 Serpentine-based asbestos fibers (length 3-10 mm) were used in the same raw material formulation as in Example 1, and this was mixed with 10% by weight of methylhydrodiene polysiloxane and 1% by weight of dibutyltin dilaurate as water repellents. Immerse in trichlorethylene solution and dry at 200℃
After baking for 1 minute and mixing in a predetermined proportion, steam-cured concrete with a specific gravity of 0.5 was produced according to normal operations and tested in the same manner as in Example 1. The results are shown in Table 2.

[Table] With the water repellent used in this example, drying and baking treatments after immersing asbestos fibers can be performed more easily than in Example 1. Test Nos. 9 to 12 in which the amount of asbestos fiber added is within the range of the present invention is Example 1.
It is recognized that it has excellent impact resistance as well. Example 3 Serpentine-based asbestos fibers (3-10 mm in length) were used with the same raw material formulation as in Example 1, treated with an ethyl ether solution containing 20 g of aluminum stearate soap as a water repellent, and dried. A predetermined proportion of the product baked at 120° C. for 2 minutes was added and mixed to obtain a product, and a performance test was conducted in the same manner as in Example 1. The results are shown in Table 3.

[Table] From the results in Table 3, it was found that Test Nos. 15-18 in which the amount of asbestos fiber added was within the range of the present invention had excellent impact resistance as in Example 1.

Claims (1)

[Claims] 1. In steam-cured lightweight cellular concrete whose main raw materials are powdered siliceous raw materials and calcareous raw materials, asbestos fibers treated with a water-repellent substance in a slurry mixture of the raw materials are added at a ratio of 0.1 to 0.1 to the total solid content. Steam-cured lightweight cellular concrete with excellent impact resistance, containing 5.0% by weight.