Method for semi-dry pressing of gypsum

FIELD: construction.

SUBSTANCE: swollen perlite is used, which is first saturated with water, water that is not retained by a swollen perlite granule is filtered, the water-saturated perlite is mixed with gypsum, the produced mix is supplied into a die mould for further pressing, and pressed at 10 MPa at least.

EFFECT: increased strength of a finished product with increased time of mortar hardening.

2 cl

 

The present invention relates to the field of construction, in particular to a method dry pressing of plaster.

The main task for semi-dry pressing of gypsum is to increase the time before the solidification of the solution, i.e. there exists a need for rapid delivery of the solution in the working area. In case of impossibility of such a quick delivery of the solution in the working area target dry pressing of gypsum will not be achieved.

There are many ways of making gypsum products using dry pressing (see, for example, patent RF №2278841 published 27.06.2006, or patent of the RF No. 2297399 published 20.04.2007), in which the plaster or gypsum with impurities interfere with the water filled in the form, and then squeezed by the press.

The main disadvantages of such methods are:

1) under normal zatvorenii water at the points of contact of the gypsum with water at any delay pressing quickly begins solidification, resulting in lumps in the total mass of the solution;

2) when compressed gypsum mass penetration of water occurs on the way from the bottom up, that does not necessarily will go evenly, and therefore, modulepage ratio may be different, and the product will not have uniform strength.

The difference of the way dry pressing of plaster from the mixing water is very low, water is ipsum ratio. The less modulepage the ratio, the stronger the resulting gypsum, but the faster it hardens. And, therefore, more dense structure cannot be used when pouring, but its strength will be much higher (for Vodopiyanov ratio of 0.2-0.3). Under normal zatvorenii water per 1 kg of gypsum accounts for about 700-800 ml of water, i.e. the ratio is 0.7 to 0.8. When semi-dry pressing modulepage ratio is 0.2-0.3, and the pressing time is a few seconds, before which the plaster does not have time to react with water.

The technical result of the present invention is to increase the strength of the final product with increasing time curing water-saturated mass.

The technical result is achieved by using dry pressing method of the plaster according to the present invention. The method includes the steps, which use expanded perlite, which is pre-saturated with water, mixing expanded perlite saturated with gypsum, serves the mixture in the mold for further pressing and pressed at a pressure of not less than 10 MPa.

An additional feature of the present invention is that the use of expanded perlite with a granule size from 75 to 100 microns and use plaster with a granule size of from 20 to 60 microns.

Another feature of N. the present invention is that, after the surgery pre-saturated with water, filtered water that is not held by the grains of expanded perlite.

The dry pressing method consists in the following. Use expanded perlite with a granule size from 75 to 100 μm. Before mixing expanded perlite with gypsum, perlite fall asleep in the water and carry out its mixtures. Then soaked expanded perlite is placed on a sieve to filter out the excess water that is not held by the grains of expanded perlite. When granules of expanded perlite will hold the amount of water that can't get out of it. In this form (water-saturated) expanded perlite is mixed with gypsum and served in the mold. The process of mixing and compaction is carried out at temperatures above zero, otherwise the dry pressing process will not be possible. When the compression of the mixture in the mold creates a pressure not less than 10 MPa (typically about 20 MPa), the microspheres of expanded perlite, dissolved, water is released and is uniform wetting of gypsum water throughout the volume.

Due to the high density of the product is due to the high compaction pressure there is practically no intergranular space, which further prevents the penetration of water in the finished product, resulting in water the absorption of the product will not exceed 5%.

To achieve the necessary Vodopiyanov the ratio of the weight of the wetted expanded perlite is clean water weight, because the weight of the perlite can be neglected (the weight of the perlite is 0.08 weight taking of water).

The plaster soaked perlite can be mixed up to 1 hour. As a result of this pressing, the resulting product may be immediately after pressing extracted from the mold, and 2 hours after compaction reaches a compressive strength of about 12-13 MPa when using gypsum G4. When fully curing (drying) the strength of the product increases to 15-17 MPa in compression, which corresponds to the compressive strength for brick.

For operations on semi-dry pressing of gypsum can be used standard equipment.

1. Method dry pressing of gypsum comprising the steps are:
- use of expanded perlite with a granule size from 75 to 100 μm, which was previously saturated with water;
- mixing expanded perlite saturated with gypsum with a granule size of from 20 to 60 μm;
applying the mixture in the mold for further pressing; and
- pressed at a pressure of not less than 10 MPa.

2. The method according to claim 1, characterized in that after the surgery, pre-saturated with water, tfilter who agree water, not held by the grains of expanded perlite.



 

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