SU775073A1 - Composition for making construction articles - Google Patents

Description

The invention relates to the building materials industry and can be used in the manufacture of gypsum wall products. In the building materials industry, for the manufacture of wall stones, gypsum or gypsum-cement-pozzolanum is used, mostly with mineral or organic aggregates or without aggregates 1. The closest in technical essence and the result is achieved is a composition for the manufacture of wall gypsum stones, including gypsum cement and water 12. However, to obtain a convenient mixture, an increased amount of mixing water is required (water gypsum ratio 0.54-0.56), which leads to a decrease in the physicomechanical properties of the products (grade 25-35). Wall stones are obtained with a large number of deep cracks and are characterized by high brittleness; as a result of this, due to the presence of frayings on the stones, dullness of edges and corners, they do not meet the requirements of the standard. In addition, the use of such a composition leads to waste of gypsum in a gang. In order to reduce the flow rate, various aggregates have to be found. The introduction of aggregates in mixtures, which differ in their mineralogical composition from that of a binder, which are practically not involved in the hardening process and are an inert filler, leads to a deterioration of the physical and mechanical properties of wall stones. The purpose of the invention is to increase the crack resistance and strength of products. The goal is achieved by the fact that the composition as a gypsum in the carrier contains semi-aquatic gypsum of the following fractional composition, wt.%: Fraction 1-3 mm 18-20 Fraction 0.30, 9 mm. 8-10 Fraction less than 0.3 mmEstalless with the following ratio of components, wt.%: Semi-aquatic gypsum 65-70 Water 30-35

The use of semi-aquatic gypsum of the above-mentioned fractional composition ensures the formation of a dense and strong structure of wall stones; this does not require the introduction of inert filler into the composition.

The proposed granulometric composition of semi-aquatic gypsum is easily obtained by grinding calcined gypsum rubble in a modernized hammer crusher without separation. During modernization in the crusher, the grate was replaced by a perforated metal sheet with slotted holes 3 mm wide, arranged in a checkerboard pattern. In connection with the abandonment of the grinding equipment, the energy consumption is reduced and the productivity of the processing line is increased.

To obtain wall stones, three mixtures were prepared, each containing semi-water gypsum with a fraction of 0.30, 9 mm 9 mass% and differing from each other with a content of semi-aqueous gypsum with a fraction of 1-3 mm, equal to 10, 20 and 30 mass in each mixture. %, as well as the content of semi-, aqueous gypsum fraction less than 0.3 mm, constituting an additional part up to 100% in each mixture.

Each molding sand is prepared with a water gypsum ratio of 0.48 and washed down in molds. After stripping, the products are tested according to PCT USSR 5003-72.

The prepared compositions have the following characteristics of physico-mechanical properties, presented in table. one.

In addition, three mixtures are prepared containing each hemihydrate gypsum

70 wt.% And differing from each other in water content equal to 30, 33 and 35 wt.% In each mixture.

Semi-aquatic gypsum take the following particle size distribution, wt.%:

Fractions 1-3 mm 19

Fractions 0.30, 9 mm9

Fraction less

Oh, 3 mm.72

Each molding mixture is poured into molds. After demolding, the products are tested on the PCT of the Ukrainian SSR 5003-72.

The prepared compositions have the following characteristics of physico-mechanical properties, presented in table. 2

The physicomechanical parameters of the proposed composition are superior to those of the well-known composition.

The optimum water content is in the range of 30-33% and with its increase, a decrease in the strength of the properties of the samples is observed.

The increase in the physicomechanical indicators of gypsum-concrete stones occurs as a result of the choice of the optimal particle size distribution of semi-aquatic gypsum and the possibility of the use of mixtures with a reduced water-gypsum ratio.

The optimum content of the semi-aquatic gypsum fraction of 1-3 mm is in the range of 18-20%, while decreasing it, deterioration of the physicomechanical properties of the samples is observed, accompanied by cracking.

The technology for making wall stones of the proposed composition does not change as compared with that used for a known composition.

Table

eleven

44

ten

10 12

49

51 47

15

14

There are

table 2

18 22 20

Missing Same

 and

Claims (2)

1. Guide to the production of hyp, sa and gypsum products. M., Gosstroyizdat, 1963, p. 38-40. . 0 2. Republican Standard of the Ukrainian SSR. Gypsum and gypsum concrete wall stones. MOUTH OF THE USSR 5003-72, Kiev, 1972.