CS229800B1 - Incombustible flexible asbestos-cement element - Google Patents

Description

The invention relates to a non-combustible flexible asbestos-cement building element.

Due to its fragility and lack of mechanical workability, a common asbestos-cement element is not suitable for many construction applications. In addition, it has a very high fire resistance due to the destruction of low porous mass by escaping water vapor at high temperatures. These properties limit its use as a sheath material up to 1 cm thick. An asbestos-cement element with increased porosity, characterized by good workability and volume stability, is known. However, this material produced using siliceous additives contains a relatively high amount of asbestos, including economically demanding long-fiber asbestos. It is therefore advisable to use this material solely for fire protection purposes. For use as sheathing material for sandwich panels and lightweight partition walls, for interior cladding and wall cladding etc. An asbestos-cement element is known whose advantage besides very good mechanical machinability and good fire resistance is the high flexibility achieved by the addition of bunioin, which together with the asbestos serves as a dispersion reinforcement. Namely, kraft pulp, ground in the range of 20 to 60, is used. To control the technological process of forming the sheet and to influence the dewatering process, especially when working with pulp, the addition of small amounts of artificial inorganic fibers with increased resistance in alkaline environments. Suitable mineral fibers with a modified composition by addition of zirconium oxide, basalt fibers and the like, characterized by a smooth surface and low water retention. The disadvantage of using these inorganic fibers is the increased production costs compared to the use of pulp alone, in terms of purchasing the necessary

229,400 raw materials, as well as the production itself, because the number of components in the preparation of the initial suspension increases.

The aforementioned drawbacks are eliminated with the non-combustible flexible asbestos cement element according to the invention, which consists in that it contains 5 to 20% by weight of chrysotile asbestos of grades 3 to 6 according to ON 72 17 40 or their binding mixtures, further 5 to 20% by weight. kraft pulp having a fineness of 5 to 40 °

SR and / or waste pulp containing 70 to 99 fibrous fractions and 50 to 90 pips of Portland cement.

The use of unground kraft pulp, possibly with a low degree of grinding or waste pulp of the same treatment, allows to omit the spin of artificial inorganic fibers while maintaining the required drainage rate and yield, as well as mechanical workability and fire resistance of the final product. This results in a reduction of raw material costs and simplification of the production technology by reducing the number of starting components.

In the production process, a kraft pulp suspension is first prepared to which asbestos is added and finally the cement or treated waste from the production of the material is mixed. The suspension obtained is dewatered in a conventional manner on a Hatsch molding machine. The obtained wet carpet is processed into molded or non-molded products, after which the final size adjustment is carried out.

The invention will be explained in more detail below with reference to exemplary embodiments.

Example 1

A slurry of 8.0 kg chrysotile asbestos # 4 15.0 kg chrysotile asbestos # 5 14.0 kg chrysotile asbestos # 27.0 kg of kraft pulp 15 ° SR 240 kg of cement was prepared as described above.

The dewatered suspension was pressed and allowed to mature for 28 days. The finished products had a bulk density

229 800

450 kg.m, flexural strength in the direction parallel to the fibers 28 MPa, in the direction perpendicular to the fibers 24 MPa.

Example 2

From a suspension of 17.0 kg chrysotile asbestos δ. 3 32.0 kg chrysotile asbestos δ. 6 21.0 kg kraft pulp 7 ° SR 250 kg cement

10.0 kg of production waste were prepared in a similar manner as in Example 1 to products having a bulk density of 1,500 kg / m @ 2, a bending strength in the fiber direction of 26 MPa, in a direction perpendicular to the fibers of 20 MPa.

Example 3

The starting suspension had the following composition:

12.0 kg chrysotile asbestos δ. 5 23.0 kg chrysotile asbestos δ. 6 42.0 kg waste pulp

260 kg of cement

15.0 kg of production waste

The resulting products had a bulk density of 1400 kg / m 2, a flexural tensile strength in a direction parallel to the fibers of 24 MPa, in a direction perpendicular to the fibers of 17 MPa.

Example 4

From the initial suspension containing 45,0 kg chrysotile asbestos δ. 5 27.0 kg Kraft pulp 10 ° SR 220 kg cement

13.0 kg of production waste was produced by dewatering and subsequent pressing products, which showed a density of 1280 kg.m, a flexural tensile strength in the fiber direction of 22 MPa, in a direction perpendicular to the fibers of 16 MPa

229 800

Finished products are designed primarily for the interior of residential, civic, industrial and agricultural buildings, family houses and cottages and for various types of flat parts. With suitable surface treatment, lightweight partition walls, inner wall cladding and inner wall cladding are applied to the walls. They can also be used for fire insulation and for wind protection of roof structures. The surface treatment can be done both by classical coatings, by dispersion spraying and wallpapering. Cutting and drilling can be done with conventional tools with reinforced tips. Products are mold resistant and according to ČSN 73 0862 are classified into category A - non-combustible.

Claims (2)

OBJECT OF THE INVENTION. Flame retardant flexible asbestos cement element, characterized in that it contains 5 to 20% by weight of chrysotile asbestos of grades 3 to 6 according to ON 72 1760 or mixtures thereof, and 5 to 20% by weight of kraft pulp having a fineness of 5 to 40 ° SR and / or waste pulp containing 70 to 99 wt.% fibrous fraction and further 50 to 90 wt.% Portland cement. H & flame / o soft 2. A cementitious element according to claim 1, characterized ⁱⁿ that it comprises up to 5 wt. % of treated waste from the production of this element.