RU2039021C1 - Method of manufacture of construction structures - Google Patents

Abstract

FIELD: manufacture of construction materials. SUBSTANCE: calcium sulfate, mineral and chemical additives are used. Earthy gypsum is used as calcium sulfate dehydrate in proportion of 0.5-1,5 parts of the whole mass. Glass powder and Portland-cement are used as mineral additives in proportion of 0.5-1.5 each of the whole mass; LST powder as chemical additive in the same proportion as the above additives. Moreover, fine-crystal fraction structure (2-10 mm) gypsum rock (heated up to 160-170 C) is introduced in the amount of 35-45 percent of building plaster. EFFECT: higher durability and lower prime cost.

Description

 The invention relates to the production of building materials, in particular to methods for manufacturing building products from gypsum.

A known method of manufacturing building products (floorboards) from gypsum by laying in the form of gypsum, water and aggregate with a ratio of 1: (0.35-0.55) (0.9-1.1), followed by compaction (pressing at 5 -25 MPa) with the simultaneous removal of excess moisture, gypsum dough is first placed in the mold, and a layer of the aggregate fraction of 2.5-5 mm or 5-10 mm is placed in it [1]
Properties of gypsum products obtained by this method:
bending strength, 1 day MPa 4-8 bending strength, 28 days 6-20
average strength, g / cm ³ 18-2.0 Moss hardness, units 3-5
The disadvantage of this method is the reduced bending strength, the complexity of the molding process equipment.

The prototype of the invention is a method of preparation from semi-aquatic (building gypsum), two-water gypsum, an alkali-containing additive (lime or cement) and a water repellent agent, followed by molding of products from the resulting mixture [2]
The disadvantages of this method is the reduced bending strength to 12 MPa.

To eliminate this drawback, a method of manufacturing construction products, by preparing a raw mixture of plaster, gypsum dihydrate powder, cement and water, followed by molding, in the raw material mixture is further added stekloporoshok, technical lignosulfonate powder and heated to 160-170 ^C. gypsum fraction 2 -10 mm in an amount of 35-45% by weight of gypsum, while the content of each of the remaining components of the raw material mixture is 0.5-1.5 parts by weight per 100 parts by weight gypsum plaster.

To implement this method, the following raw materials were used:
Portland cement in accordance with GOST 10178-76 of the Ulyanovsk plant brand 400,
glass powder obtained by grinding sheet cullet according to GOST 111-78,
technical lignosulfate (LST) according to GOST 1.2 13-183-83,
gypsum stone fraction 2-10 mm and gypsum flour GOST 4013-82 Arakchinsky gypsum plant TSSR.

The introduction of small amounts of Portland cement, glass powder, gypsum flour and dry powder LST into the composition of the gypsum binder helps to reduce microcracking during hardening of the gypsum stone, which leads to an increase in bending strength. Gypsum heated to 160-170 ^{° C} also improves the flexural strength by increasing the adhesion to the gypsum binder, since its surface has active nuclei in the form of CaSO ^_4. 0.5 Н ₂ О, during compaction, the aggregate creates high local pressures reaching 7000-20000 MPa, and during hardening it reduces the volumetric deformation of gypsum stone. Excess moisture is removed due to its accumulation by the surface of the active (heated) aggregate in the process of self-vacuuming. Microscopic studies showed a decrease in the number of microcracks, especially when using a filler (gypsum stone with a fine-grained structure, and X-ray diffraction analysis showed that CaSO _{4 is} almost absent in the hardened gypsum binder ^. 0.5 Н ₂ О, i.e. the hydration process proceeds most fully.

 The method was carried out in the following way.

Activated gypsum binder was preliminarily prepared by co-grinding building gypsum, gypsum flour, glass powder, dry powder LST and Portland cement to a specific surface of 500-1000 cm ³ / g. Then loaded activated form gypsum binder (mixing with water), heated to 160-170 ^C gypsum fr. 2-10 mm and the mold was vibrated for 30-50 s and then the resulting product was left in the mold for 30 minutes and unformed.

 In the table. 1 presents examples of the composition of the components of the activated gypsum binder.

 Table 2 presents the properties of the products, in the manufacture of which used building gypsum brand G4-G5, and in table 3 building gypsum brand G9-G10.

 Table 4 shows the dependences of the properties of gypsum products (Example 2 of Table 1) on the heating temperature of gypsum stone (aggregate).

 In the table. 5 shows the dependence of the properties of gypsum products (example 2, table 1) on the structure of gypsum stone.

 Table 6 presents the properties of gypsum products (example 2, table 1) depending on the fractional composition of gypsum stone (aggregate).

 Unlike the prototype, building products according to this method have increased bending strength, hardness and reduced cost due to the saving of 35-45% of gypsum, and the gypsum binder does not require ultra-fine grinding.

Claims (1)

METHOD FOR PRODUCING BUILDING PRODUCTS by preparing the raw mix from building gypsum, gypsum powder, cement and water, followed by molding, characterized in that glass powder, technical lignosulfonate powder and gypsum stone of fraction 2 10 mm heated to 160 170 ^o C are added to the raw mix in the amount of 35 45% by weight of gypsum, while the content of each of the remaining components of the raw mix is 0.5 to 1.5 wt.h. per 100 parts by weight gypsum plaster.

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