RU2595016C1 - Fire-retardant fibre-vermiculite-concrete crude mixture - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention can be used by industrial and construction organisations for fireproofing of building structures. Fire-retardant crude mixture for making of fireproof coating contains, MP: portland cement - 8.4-13.2; expanded vermiculite of 0.16-5 mm fraction - 16.47-21.32; volcanic ash of 0-0.16 mm fraction - 9.2-15.2; basalt fibre - 1.0-1.5; wood saponified resin - 0.08-0.13; unslaked lime - 8.1-13.3; gypsum plaster - 0.4-0.6; water - the rest.

EFFECT: higher fire resistance of building structures, reduced specific consumption of portland cement, increased strength of vermiculite concrete, higher crack resistance and fire-retardant properties of the coating during fire, wider raw material base.

1 cl, 3 tbl

Description

The invention relates to the construction materials industry and can be used by industrial and construction organizations for fire protection of concrete, reinforced concrete and metal structures.

Known flame retardants on Portland cement, gypsum, water glass, alumina cement with various additives [1, 2, 3, 4, 5]. Expanded vermiculite and perlite are used as porous aggregates.

The closest are raw mixes for the manufacture of fire retardant coatings using Portland cement, expanded vermiculite, sawdust from volcanic tuff, saponified wood resin, quicklime and building gypsum [6].

The disadvantages of these compositions are the insufficient raw material base of volcanic tuff sawing waste, relatively low tensile strength and bending of vermiculite concrete, a relatively high thermal conductivity and low crack resistance of the coating at high temperatures during a fire.

The objective of the invention is to expand the raw material base, reduce the specific consumption of Portland cement, increase the strength of vermiculite concrete, increase crack resistance and fire retardant properties of the coating during a fire.

The problem is solved through the use of Portland cement, expanded vermiculite, volcanic ash, quicklime, gypsum, basalt fiber and saponified wood tar (SDO) in a fire retardant raw material mixture.

The studies used Portland cement ПЦ500-DO manufactured by Belgorodsky Cement CJSC, a gypsum binder of the Ust-Dzhegutinsky gypsum plant brand G-5 BII. As an active mineral additive, volcanic ash of the Zayukovsky deposit of a fraction of 0-0.16 mm was used.

The chemical composition of volcanic ash is presented in table 1.

Aggregate - expanded vermiculite of the St. Petersburg mica factory fraction 0.16-5 mm.

The particle size distribution of expanded vermiculite is shown in table 2.

.For dispersed reinforcement of the composite, basalt fiber manufactured by Ivotsteklo OJSC of the RNB-9-1200-4c grade was used, the ratio of fiber length to diameter based on preliminary experiments was adopted $$\raisebox{1ex}{$l$}\!\left/ \!\raisebox{-1ex}{$d$}\right.=1444$$

.

To improve the rheological characteristics of the proposed fire-retardant raw material 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).

Lumpy air is first crushed in a jaw crusher, then finely ground in a ball mill. Volcanic ash is sieved through a sieve No. 0,16 and dried in an oven to constant weight.

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 Portland cement, gypsum, lime, basalt fiber, volcanic ash, then expanded vermiculite, or a premixed dry mixture of Portland cement, gypsum, quicklime, basalt fiber are sequentially loaded volcanic ash and expanded vermiculite. Mixing of all components is continued until a uniform fire retardant fiber-vermiculite-concrete raw material mixture is obtained. The duration of mixing the mixture is 1.5-2 minutes

To study the fire-retardant effectiveness of the proposed fiber-reinforced concrete compositions, reinforced cement slabs with a fire-retardant layer were formed. 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 on a vibrating platform from a mixture with a mobility of 3-5 cm by immersion of the StroyTSNIL cone. Fire-retardant coating is also applied to metal and reinforced concrete structures in a construction site using fine-mesh mesh manually or mechanized 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 layer boundary) 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 fiber-vermiculite-concrete raw material mixture according to the invention and their main physicomechanical properties, fire resistance limits of two-layer reinforced cement slabs are shown in table 3. Table 3 also shows the test results of reinforced cement slabs with a fire-retardant layer based on control compositions using sawdust from volcanic tuff fraction 0- 2.5 mm.

From table 3 it can be seen that with a lower consumption of Portland cement and at approximately the same density, the developed fibro-vermiculite-concrete compositions have higher compressive and bending strengths.

This is due to the fact that volcanic ash is used fractions from 0-0.16 mm, which increases the content of the chemically active component in contrast to the tuff sand fraction up to 2.5 mm used in the prototype. The highest flame retardant properties are possessed by compositions with an average density of 480-570 kg / m ³ .

The introduction of basalt fibers increases the compressive strength of a fiber-reinforced concrete composite by 1.28 times, and by bending, by 1.85 times with respect to the strength of the initial matrix. Compared with the prototype, the compressive strength of the fiber-reinforced concrete composite increases 2.22 times, and bending - 3.25 times. This will make it possible to produce large-sized fiber-vermiculite-concrete products. In addition, reinforcing the initial matrix with basalt fibers increases the crack resistance and fire retardant properties of the coating due to the perception of tensile temperature stresses during a fire.

Information sources

1. USSR copyright certificate No. 893944. IPC C04B 15/02. Raw mix for the manufacture of fire retardant coating / Komar A.G., Topchiy V.D. and others // B.I. No. 48, 12.30.81.

2. RF patent No. 2173309. IPC C04B 41/65. Plaster composition for fire protection of building steel structures / Rubin M.M., Sheinin E.I., Kitaykin V.D. // B.I. No. 25, 09/10/2001.

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

4. 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.

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

6. Khezhev T.A., Khezhev H.A. RF patent No. 2372314. Fireproof raw material mix // Bull. No. 31. 2009.

Claims (1)

Fire retardant raw material mixture for the manufacture of a fire retardant coating, including Portland cement, porous aggregates, water and additives, characterized in that it contains expanded vermiculite fraction 0.16-5 mm and volcanic ash fraction 0-0.16 mm, which is simultaneously both active mineral additive, and as additives - quicklime, gypsum, basalt fiber and saponified wood resin in the following ratio of components, wt. %:
Portland cement 8.4-13.2 Expanded Vermiculite 16.47-21.32 Volcanic ash 9.2-15.2 Saponified wood resin 0.08-0.13 Quicklime 8.1-13.3 Gypsum plaster 0.4-0.6 Basalt fiber 1.0-1.5 Water rest