RU2384541C2 - Raw mixture for manufacture of unshrinkable construction material - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: raw mix contains industrial gypsum, water and additives in the form of potassium sulfate and sodium chloride, at the following ratio of components, wt %: industrial gypsum 65-70; potassium sulfate 1.4-2.0; sodium chloride 1.5-2.0; water - the rest.

EFFECT: improved strength of material simultaneously with reduction of its cost.

1 tbl, 3 ex

Description

The invention relates to the field of building materials, in particular to the production of gypsum products, for example wall blocks and plates for building partitions.

It is known that in the manufacture of plates for partitions, a gypsum binder with mineral or organic additives or without additives is used (GOST 6428-83 "Plaster plates for partitions. Technical conditions"). The material has a compressive strength in the dried state of at least 5 MPa, a bending strength of at least 2.4 MPa.

The disadvantages of this material are its low strength and high cost.

Closest to the claimed technical essence is a binder intended for use in the production of gypsum products, containing semi-aquatic gypsum and an additive - a waste product from the production of methyl methacrylate (Patent 2155171, Russia. Astringent. Ivaschenko Yu.G., Polyakov A.V. Declaration 03.10. 1996, published on August 27, 2000, Bulletin No. 7). When using this binder, the setting time is reduced while maintaining sufficient strength of the products and their cost is reduced. The disadvantage of this technical solution is the low compressive strength.

The invention solves the problem of increasing the strength of gypsum products and at the same time reducing their cost.

This is achieved by the fact that the raw mixture contains technogenic gypsum, water and additives in the form of potassium sulfate and sodium chloride, in the following ratio of components, wt.%:

Man-made gypsum 65-70,

Potassium sulfate 1.4-2.0,

Sodium Chloride 1.5-2.0,

Water is the rest.

The use of man-made gypsum allows to increase the strength of the finished product under compression due to the formation of high density gypsum stone

The content of man-made gypsum in an amount of less than 65 wt.% Does not provide the required strength of the material obtained, and in an amount of more than 70 wt.% Does not provide the necessary mobility of the mixture.

Potassium sulfate forms an unstable intermediate compound with water and man-made gypsum, accelerating the hydration of man-made gypsum. As a result, the acceleration of the setting and hardening times occurs, which leads to an increase in the strength of the obtained material under compression at a daily age.

The content of potassium sulfate in an amount of less than 1.4 wt.% Does not provide sufficient acceleration of the setting process, and in an amount of more than 2.0 wt.% Complicates mixing due to too quick setting.

The presence of sodium chloride allows you to accelerate the processes of crystal formation, which leads to an increase in the strength of the material up to 28 days of hardening.

The content of sodium chloride in an amount of less than 1.5 wt.% Does not improve the strength properties of the material, in an amount of more than 2.0 wt.% Leads to the formation of efflorescences on the surface of the material.

The total content of additives should be in the range of 3.0-3.5 wt.%, Which is necessary to intensify the setting and hardening of the mixture. With a lower value, the material will have low strength in the early stages, with a larger amount, laying and compaction of the material is difficult.

The reduction in the cost of gypsum products is ensured by the fact that the main component of the raw material mixture is man-made gypsum - a waste product from hydrofluoric acid production from feldspar.

The raw material mixture is prepared as follows.

Man-made gypsum is subjected to grinding to a specific surface of 3000-4000 g / cm ² , then mixed until dry with a uniform state with potassium sulfate and sodium chloride. The resulting dry mixture is shut with water, mixed thoroughly and molded products by casting. The products are kept in molds at room temperature for a day, after which they are redistributed and stored for 28 days.

Example 1

Technogenic gypsum was milled to a specific surface area of 3500 g / cm ² , a weighed portion of 1000 g was taken, mixed dry to a homogeneous state with potassium sulfate in an amount of 20 g and sodium chloride in an amount of 30 g. The resulting dry mixture was closed with 425 ml of water. Samples were molded from the resulting mixture.

Hardening occurred at an air humidity of 60-80% and an air temperature of 20 ± 2 ° C for 28 days.

Example 2

We took the following composition, g:

Man-made gypsum 1000 Potassium sulfate 25 Sodium chloride 25 Water 425.

Samples were prepared according to the method described in example 1.

Example 3

We took the following composition, g:

Man-made gypsum 1000 Potassium sulfate 22 Sodium chloride thirty Water 425.

Samples were prepared according to the method described in example 1.

The results obtained are illustrated by the data given in the table.

Table No. p / p Composition, wt.% The compressive strength after 1 day, MPa The compressive strength after 28 days, MPa one Man-made gypsum 1000 8.2 29.2 Potassium sulfate twenty Sodium chloride thirty Water 425 2 Man-made gypsum 1000 8.0 28,4 Potassium sulfate 25 Sodium chloride 25 Water 425 3 Man-made gypsum 1000 8.1 25.8 Potassium sulfate thirty Sodium chloride 22 Water 425

Products obtained from the inventive raw mix have high strength and cost-effectiveness. The use of man-made gypsum, which is a waste of the production of hydrofluoric acid from feldspar and located in dumps, can improve the ecological situation of the region and its storage.

Claims (1)

A raw mixture for the manufacture of gypsum products containing gypsum, water and additives, characterized in that it contains technogenic gypsum, and as additives, potassium sulfate and sodium chloride in the following ratio, wt.%:
Man-made gypsum 65-70 Potassium sulfate 1.4-2.0 Sodium chloride 1.5-2.0 Water Rest