SU84387A1 - A method of manufacturing cardboard-reinforced products from gypsum sawn masses - Google Patents

Description

The subject of the invention is a method of making articles reinforced from the surface of a cardboard from hyiso-onylic masses.

A distinctive feature of the proposed method is that, in order to obtain a product of high mechanical strength at minimum moisture and after molding, the working mass consisting of a mixture of semi-ahydrous gypsum powder and sawdust pre-moistened with the amount of water necessary for hydration of gypsum is placed in a press - the form between two sheets of PVC: laminated cardboard, with a layer of pure gypsum between the mass and the cardboard, is molded under pressure and aged in a compressed state until hardened. After hardening, the molded product is removed from the mold and kept under conditions that exclude the possibility of warping until the necessary strength is obtained.

The essence of the proposed method consists in the following. Completely loose working weight, prepared by displacing construction or molding gypsum with sawdust sifted through a sieve (with a cell size of not more than 3 mm), minimally moistened with the amount of water necessary for full hydration of ioluvodny gypsum, and placed in a suitable mold between two sheets wet cardboard, compressed on a press under some pressure and in a compressed state is held until cured. Thereafter, the molded product is removed from the i-mold and placed in a shtabel where it is kept for several hours until the desired strength is obtained.

With the right dosage of water, the product is obtained with a final moisture content not exceeding the natural one in normal conditions.

No. 84387 2 shrinkage, due to which the operation day can be excluded from the technological process.

The products obtained in this way have a high mechanical strength, because the process of hygiene is carried out under pressure and with the minimum required water content.

The composition of the mass can vary within very wide limits. Irakpcheskp acceptable should be considered content in the mass of air in dry sawdust (assuming their absolute moisture content lovi)) in limits from 8 to 40% by weight of gypsum.

The total pressure of the sawdust within the limits of 20–40 can be considered completely sufficient for the indicated limits. moreover, the shutter speed of products in a compressed state can be reduced by npii lowered against the pressure, 1pp pressure. At Go.iee high x, but compared with the above, it is possible to manufacture products of mass ii3, content of air-dry sawdust up to 6 kg of weight of gypsum.

The time required to hold products in a compressed state depends, depending on the composition of the mass of CBOIICTB gypsum and practically varies from 15 to 60 minutes, increasing the increase in the content of sawdust.

The working mass prepared by the methods described above for a long time retains its activity, since almost all the water introduced into it is in the burrows of sawdust and until it is molded in contact with gypsum, a small fraction of it falls. When molded, the bulk of the water is squeezed out of the molds, fills the space between the gypsum parts, displaces the remaining air, and reacts with the semi-drained 1IS. The retention time of such a lag of activity until form is approximately 5–15 minutes and depends on the properties of the gypsum, the composition of the mass, and the particle size of the minerals. According to the p-stechenen of the indicated period, the gypsum is visibly hydrated, Aiacca dries out and slightly heats up, the nose, which becomes unsuitable for molding.

In order to significantly increase the duration of preserving a mass of activity until the formation, on the surface of the particles of the vaporized onilok before mixing them with h; a dog skin is applied to a sewn sheath containing a setting of giisa, which is ignored; This is a sharp decrease in the concentration retarding solution concentration.

Most commonly, the method of applying the coating is that wetted (slightly smaller than the calculated amount of water) and, at the intensity of their unmixing, sprinkle with a small amount of hins setting retarder solution. This method of processing sawdust makes it possible to obtain a working mass that retains its activity R for an hour or more with a relatively low consumption of the retarder. When forming the mass, the water is extracted from the sawdust and the water drastically reduces the concentration of the retarder, as a result of which the plaster hardening process is slowed down very slightly.

Among other ways of applying a temporary protective coating on the surface of sawdust particles before mixing them with gypsum, you can specify, and a nrn measures, the following:

a) the wrinkling of moistened onilok with finely powdered dry mink powder retarder skvvatshapi rtmca;

b) preliminary sifting out of the fine fraction of sawdust (less than 1 mm), moistening them with a solution of set retarder and subsequent;

mixing with water moistened sawdust with a particle size of from 1 to 3 mm.

Subject invention

Claims (2)

1. A method of manufacturing gypsum-sawdust mass products reinforced from the surface of the cardboard, characterized in that, in order to obtain products of high mechanical strength with minimum final moisture after molding, the working mass prepared by mixing the powder of semi-aquatic hins with the previously moistened hydration with the amount of water in sawdust, placed in the appropriate mold between two sheets of cardboard, wetted from the side of the cardboard adjacent to the mass, using between the mass and cardboard of pure gypsum interlayers, they are molded with pressure and maintained in a compressed state until hardening, after which the molded product, extracted from the iress-form, is kept under conditions that exclude the possibility of warping, until it acquires the necessary strength. 2. Acceptance of the method according to claim., Characterized in that. in order to impart a working mass to the properties for a long time to preserve their activity before molding, a protective coating containing the retarding agent of gypsum setting, which practically stops during molding due to a sharp decrease in the setting retarder solution, is applied to the surface of the particles of wetted sawdust . № 84387