RU2341477C1 - Binding agent and method of its preparation - Google Patents

Abstract

FIELD: chemistry, construction.

SUBSTANCE: binding agent includes, wt %: semi-water gypsum of β-modification -57.3-62.9, grinded basic granular blast-furnace slag - 15.2-16.25, caustic magnesite - 10.8-16.25, clyite dust from cyclones - 0.45-0.9, bischofite solution with density 1.2 g/cm³ in terms of magnesium chloride MgCl₂ -9.75-10.2. Method of preparation of said binding agent includes mixing said gypsum, said slag and caustic magnesite, tempering of dry mixture with bischofite solution with density 1.2 g/cm³ and further introduction of said dust 1-2 min before formation.

EFFECT: increase of strength under compression, extension of stiffening terms, reduction of binding agent water resistance.

2 cl, 2 tbl

Description

The invention relates to a binder composition and a method for its preparation and can be used for the manufacture of wall products from lightweight concrete and thermal insulation products for walls and other structures.

Known astringent, including ground:

high-strength steaming gypsum stone (α-modifications), acid blast furnace slag - blast furnace waste and additionally an air binder - quicklime in the following ratio of these components, wt.%:

Ground:

steamed gypsum 68-73 granular acid slag - waste domain production 24-30 quicklime 2-3

The composition of such a binder was developed by the Krasnoufimskiy factory of large-sized products in 1977 (VTU-1-77).

Known binder has a high water resistance To _size = 0.60 ÷ 0.65 and a relatively high grade for strength M100-M300, as well as slower setting time.

Along with the advantages, there are also disadvantages:

- complicated cooking technology associated with steaming gypsum stone and calcining limestone to produce lime;

- low water resistance To _size <0.8.

The closest composition of the binder to the proposed is given in ed. testimonial. USSR No. 1303586, MKl. C04B 28/14; 7/04, publ. 04/15/87, including components in the following ratio, wt.%:

semi-aquatic building plaster 73-97 iron waste blast furnace gas treatment 2-17 caustic magnesite 1-10

The disadvantages of a binder include:

- high water resistance (K _size > 0.8).

Disadvantages:

- low compressive strength R = 4,28-6,2 MPa _{compression channel;}

- short setting time, complicating the technology for producing concrete on its basis: the beginning of setting 6-9 minutes, the end of setting 13-15 minutes

The objective of the proposed technical solution is to increase the compressive strength, extend the setting time, lower the water resistance of the binder.

The binder, including β-modified semi-aquatic gypsum, blast furnace waste, caustic magnesite, bischofite solution, contains bischofite solution with a density of 1.2 g / cm ³ , ground granulated blast furnace slag and additional aluminosilicate additive - expanded clay from cyclones in the following ratio of components, wt.%:

specified gypsum 57.3-62.9 specified slag 15.2-16.25 caustic magnesite 10.8-16.25 indicated dust 0.45-0.9 bischofite solution with a density of 1.2 g / cm ³ in terms of magnesium chloride MgCl ₂ 9.75-10.2

The method of preparation of a binder according to claim 1, comprising mixing said gypsum, said slag and caustic magnesite, mixing the dry mixture with a bischofite solution with a density of 1.2 g / cm ³ and then introducing said dust 1-2 minutes before molding.

In table 1 - the composition of the binder prepared by the proposed method. Properties of the proposed binder composition.

Table 2 shows the composition of the binder prepared by the proposed method, taking into account MgCl ₂ introduced into the composition with bischofite solution.

The method of preparation of the binder.

A known method of preparing a gypsum binder to determine the standard consistency (normal density) according to GOST 23789-79 "Gypsum gypsum" p. 4.1-4.3, followed by determination of the compressive strength of the hardened dough after 2 hours in the form of samples 16 × 4 × 4 cm in size (GOST 23789 - 79 p. 5.1-5.5).

Due to the fact that the proposed binder composition contains more than 50% of construction semi-aquatic gypsum of β-modification, the known method (analog) is partially accepted as the basis.

The closest way to prepare a binder to the proposed is given in Auth. Testimonial. USSR No. 1303586, MKl. C04B 28/14; 7/04, publ. 04/15/87, Bull. No. 14.

The essence of the known method is as follows:

A mixture is dosed by weight, including wt.%: Semi-aquatic gypsum 73-97, caustic magnesite 1-10, iron-containing blast furnace waste 2-17, followed by mixing and mixing of the dry mixture with an aqueous solution of six-water magnesium oxychloride (bischofite) MgCl ₂ · 6H ₂ O with a density of 1.1% or a concentration of 30% (and anhydrous MgCl ₂ - 12% concentration) based on the preparation of a suspension mixture of normal density (spread of the test with a Suttard viscometer 180 ± 5 mm).

The suspension mixture is molded by casting in metal molds measuring 16 × 4 × 4 cm, and after the end of setting, the samples are redissembled and, after hardening in air, were tested for strength and water resistance after 2 hours and 28 days. But they are tested for strength according to the methods of GOST 23789-79 and "Cement gypsum" 5.1-5.5.

The known method, along with the advantages (simplicity of molding technology - casting method, achieving high water resistance), has the following disadvantages:

1. The low compressive strength after 28 days of hardening in air _{compression channel} R = 4,28-6,2 MPa, which makes it difficult to not lower than B10 concrete.

2. Short setting time, which complicates the technology of manufacturing concrete based on it.

The proposed binder is molded by molding. The binder was tested for strength after 28 days of hardening in air, due to the delayed setting time and slower hardening. Normal binder density, setting time, compressive strength (R _cr , MPa) are determined according to GOST 23789-79 “Plaster binders”. Table 1 shows the composition of the binder taking into account MgCl ₂ and the proposed method for its preparation, as well as the corresponding properties of the binder R _cr and K _size .

1. The composition of the binder is a composition consisting of two binders of air hardening (gypsum and magnesia) with the addition of activating substances: ground blast granulated main slag and expanded clay dust from cyclones - a waste from the production of expanded clay.

2. Increases compressive strength in 2.4-5.7 times.

3. The composition of the proposed binder similar to the composition of the prototype is among the waterproof materials, because To _size > 0.8.

4. The setting time is reduced, which simplifies the technology of manufacturing concrete and other building products based on it.

Achieving this goal is achieved by the following physical and mechanical processes and positive factors, specifically:

1. The increase in strength is ensured by: adding to the gypsum low-strength binder a more durable magnesia binder.

2. Magnesium oxide increases the hydraulic activity of ground granulated slag (basic modulus), and therefore, the strength of granulated slag and mixed binder in general, this also contributes to the preservation of water resistance (see AA Pashchenko, VP Serbin and others. “Binding materials ", - Kiev, Vishcha school, 1975. 444 p., Specifically p. 316-319).

3. Using a more concentrated bischofite solution, the plasticization of the dough from the binder is enhanced and the amount of water introduced with bischofite is reduced to obtain a suspension mixture of normal density, i.e. in the prototype, the water consumption is 42.4 wt.%, and in the proposed 36.2 ÷ 37.7 (see table 2), which helps to increase strength and water resistance.

4. With an increase in the composition of the binder fraction of gypsum hemihydrate, a decrease in strength and water resistance is observed, but the setting process is accelerated, which is very important and appropriate, gypsum binder is cheaper than magnesia.

5. The introduced expanded clay dust performs three positive functions:

a) slows down the setting time, because temporarily adsorbs micropores to water, which inhibits the hydration reactions of gypsum, caustic magnesite and granulated slag;

b) increases crack resistance during hardening;

c) promotes coagulation and demolition of metal forms until the end of setting, i.e. accelerates the turnover of metal forms, i.e. expanded clay dust is introduced into the binder 1-2 minutes before molding. It is not advisable to introduce expanded clay dust before mixing with bischofite, since this complicates the process of feeding the binder to the molding site by pump injection. The composition of the binder that promotes the disposal of three wastes, specifically: expanded clay dust from cyclones and caustic magnesite, which also settles in cyclones in the production of magnesite refractories in Sadki (see GOST 1216-87 “Magnesite caustic powders PMK-90”), as well gravel slag is utilized - a blast furnace waste.

A bischofite solution with a density of 1.2 g / cm ^{3 is} compensated by a higher strength per unit consumption of the binder, and the adaptability of its use due to the setting, since without plaster, it does not set.

The developed composition of the binder and the method of its preparation is more profitable in comparison with the gypsum binder grade G4-G5 due to the increased water resistance, strength and delayed setting time, i.e. the scope of the proposed binder becomes wider.

Claims (2)

1. Binder including hemihydrate gypsum β-modification, exhaust blast furnace, caustic magnesite, bishofit solution, characterized in that it comprises a solution bishofit density of 1.2 g / cm ^3, as a waste blast furnace - main ground granulated blast furnace slag, and additional aluminosilicate additive - expanded clay dust from cyclones in the following ratio of components, wt.%: specified gypsum 57.3-62.9 specified slag 15.2-16.25 caustic magnesite 10.8-16.25 indicated dust 0.45-0.9 bischofite solution with a density of 1.2 g / cm ³ in terms of magnesium chloride MgCl ₂ 9.75-10.2 2. The method of preparation of a binder according to claim 1, including mixing the specified gypsum, the specified slag and caustic magnesite, mixing the dry mixture with a bischofite solution with a density of 1.2 g / cm ³ and the subsequent introduction of the specified dust 1-2 minutes before molding.