RU2385851C1 - Crude mixture for making fireproof coating - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to the industry of construction materials and can be used in industrial and construction organisations for fireproofing building structures. The crude mixture for making fireproof coating contains the following in wt %: gypsum 14.6-21.7; foamed vermiculite 33.4-50; wastes from sawing volcanic tuff 22.5-33.3; caustic lime 7.83-11.5; saponified wood resin 0.07-0.1. ^ EFFECT: increased fire-resistance of building structures due to reduced thermal conductivity of fireproof concrete in case of fire with simultaneous reduction of specific consumption of gypsum without reduction in strength. ^ 3 tbl

Description

The invention relates to the building materials industry and is intended for fire protection of steel, reinforced concrete and reinforced cement structures in civil, industrial and rural construction.

Known flame retardants on Portland cement, gypsum, water glass, alumina cement with various additives [1, 2, 3]. Expanded vermiculite and perlite are used as porous aggregates.

The closest are raw mixes for the manufacture of fire retardant coatings using gypsum, expanded perlite and granular mineral wool [4], having the following composition, wt.%:

gypsum 59-85 expanded perlite 12.5-25 granular mineral wool 2.6-16.

The disadvantages of these compositions are the high consumption of gypsum, a relatively high coefficient of thermal conductivity and low crack resistance of the coating at high temperatures during a fire.

One of the materials that are an effective replacement for part of gypsum and aggregate for flame retardants may be tuff sand - waste from sawing of volcanic tuff. The feasibility of using volcanic tuff sawing waste as a filler of a heat-fire-retardant mortar and concrete is due to high refractoriness of 1200-1280 ° C, porosity, in addition, pulverized tuff sand fractions are an active hydraulic additive that reduces the consumption of binder.

The objectives of the invention are to reduce the specific consumption of gypsum without compromising strength, reducing the thermal conductivity of flame retardant concrete and mortar, increasing the crack resistance of the coating and expanding the raw material base.

The tasks are solved by using gypsum, expanded vermiculite, sawdust from volcanic tuff, quicklime, and saponified wood tar (SDO) in a fire-retardant raw material mixture.

Gypsum semi-water gypsum grade G-5, normally hardening, medium grinding corresponded to the requirements of GOST 125-79.

Powdery calcium lime powder from the Uglovskiy lime plant was in accordance with GOST 9179-77.

To improve the rheological characteristics of the flame retardant mixture and the physicomechanical properties of the mortar and concrete, we used the surface-active air-entraining additive SDO developed by the All-Russian Research Institute of Iron Reinforced Concrete and Central Research Institute of Chemical Engineering (TU-81-05-2-78).

The chemical composition of volcanic tuff sawing waste is presented in table 1.

Table 1 The content of the main components in% by weight SiO ₂ Al ₂ O ₃ Fe ₂ About ₃ CaO MgO TiO Na ₂ O + K ₂ O SO ₃ p.p.p. 73.1 13.75 1.75 1.65 1.12 0.23 3.87 0.12 2.0

The maximum grain size of volcanic tuff sawing waste was 2.5 mm.

Expanded vermiculite - Kovdor deposit with the largest grain size of 5 mm and bulk density of 140 kg / m ³ .

Granulometric compositions of vermiculite and tuff sand are shown in table 2.

table 2 Granulometric composition of aggregates Name of material Private sieve residues,% Passed through 0.14 sieve 2.5 1.25 0.63 0.315 0.14 Vermiculite 26.0 21.3 30.6 14,4 5.1 2.6 Tuff sand - fifteen eighteen 21 eleven 35

Lumpy air is first crushed in a jaw crusher, then finely ground in a ball mill. Volcanic tuff sawing waste is sieved through a No. 2.5 sieve and dried in an oven to constant weight. Expanded vermiculite is sieved through a No. 5 sieve.

The preparation of the mixture is carried out in a forced-action mixer, in which, after supplying water with the addition of SDO, a mixture of gypsum and lime, then tuff sand and expanded vermiculite, or a premixed dry mixture of gypsum, quicklime, tuff sand and expanded vermiculite are successively loaded. Mixing of all components is continued until a uniform flame retardant feed mixture is obtained. The duration of mixing the mixture is 1.5-2 minutes

To study the fire-retardant effectiveness of the proposed flame retardants, the reinforced cement slabs were formed with a fire-retardant layer. The cement-cement layer was formed on a standard vibrating platform, the fixation of the fine mesh and bar reinforcement is performed by known methods. The fire-retardant layer is formed by injection molding and natural drying is carried out in air-dry conditions. Fire-retardant coating is also applied to metal, reinforced concrete and reinforced-cement structures in the conditions of a construction site manually or mechanically using plaster aggregates of domestic or foreign production.

Fire tests were carried out on samples with dimensions of 190 × 190 mm on an electric furnace in a horizontal position according to the temperature regime of a “standard” fire, regulated by GOST 30247.0-94. The fire resistance limit on the bearing capacity (R) of reinforced cement slabs was estimated by heating the woven mesh in the structural layer (at the boundary of the layers) to 300 ° C. The moisture content of the fine-grained concrete of the cement-cement layer and the flame retardant composition at the time of testing was 3-4% and 8-10%, respectively. During the fire tests of the two-layer elements, violations of their integrity were not detected.

The compositions of the fire-retardant raw material mixture according to the invention and their main physical and mechanical properties, the fire resistance limits of two-layer reinforced cement slabs are shown in table 3. Table 3 also shows the results of comparative tests of reinforced cement slabs with a fire-retardant layer based on control compositions close to the prototype compositions. This is due to the fact that the flame retardant properties of the compositions of the prototypes were determined for steel load-bearing elements.

Table 3 Reinforced cement layer, mm Fire retardant layers, mm thick The ratio of components in the mixture, wt.% The average density ρ, kg / m ³ Tensile strength, MPa Fire resistance of plates, min gypsum vermiculite tuff sand lime FROM TO bearing capacity (R) thermal insulating ability (E) under compression when bending one 2 3 four 5 6 7 8 9 10 eleven 12 Reinforced cement slabs with a fire retardant layer based on control compositions close to those of the prototype twenty fifteen 66.6 33,4 - - - 730 1,6 1,1 42 47 twenty fifteen fifty fifty - - - 540 0.9 0.6 62 65 twenty twenty fifty fifty - - - 540 0.9 0.6 200 80 twenty 25 fifty fifty - - - 540 0.9 0.6 240 97 Armored cement slabs with a fire retardant layer based on developed formulations twenty fifteen 21.7 33,4 33.3 11.5 0.1 720 1.65 1,1 48 fifty twenty fifteen 14.6 fifty 22.5 7.83 0,07 540 0.85 0.6 68 70 twenty twenty 14.6 fifty 22.5 7.83 0,07 540 0.85 0.6 220 87 twenty 25 14.6 fifty 22.5 7.83 0,07 540 0.85 0.6 260 107

From table 3 it can be seen that with a lower consumption of gypsum and with approximately the same density and compressive strength and bending of fire-retardant concrete (mortar), the proposed compositions provide higher limits of fire resistance of cement-cement slabs, which is due to the porosity and hydraulic activity of sawn waste of volcanic tuff, as well as air entrainment FROM TO. The highest fire retardant properties have compositions with an average density of 540 kg / m ³ . The use of quicklime as a causative agent of the latent hydraulic activity of tuff sand allows to reduce the consumption of gypsum by 2 or more times without reducing the strength of the fire retardant solution. In addition, the setting time is slowed down, and the softening coefficient of gypsum concrete and mortar increases.

Information sources

1. Strakhov V.L., Garashchenko A.N. Fire protection of building structures: modern means and methods of optimal design // Building materials. 2002. No.6. C.2-5.

2. Copyright certificate of the USSR No. 275342. IPC E04B 1/94. Composition for coating metal elements / Schipanov A.I., Labozin P.G. // BI No. 22, 07/03/1970.

3. Guidance on the composition and use of heat-insulating and fire-resistant perlite plasters. M .: Stroyizdat, 1975 .-- 15 p.

4. Guidelines for the implementation of fireproof and heat-insulating plasters in a mechanized way. M .: Stroyizdat, 1977 .-- 46 p.

Claims (1)

The raw material mixture for the manufacture of a fire-retardant coating, including gypsum and porous aggregates, characterized in that it contains expanded vermiculite and volcanic tuff sawing waste, which are both an active mineral additive, and as additives, quicklime and saponified wood resin the next time the ratio of components, wt.%:
gypsum 14.6-21.7 expanded vermiculite 33,4-50 volcanic tuff sawing waste 22.5-33.3 quicklime 7.83-11.5 saponified wood resin 0.07-0.1