CS222944B1 - Non-combustible asbestos-board - Google Patents

Abstract

Non-combustible asbestos-cement board Intended for use in building interiors · The purpose of the invention is to reduce the asbestos content, in particular to eliminate econonium-intensive long-fiber asbestos and the use of varietal pulp while maintaining good resistance to fire and machinability and achieving a new and best-performance board. These plates contain from 38 to 78% by weight of Portland cement, from 15 to 35% by weight of ohrysotile asbestos chalk 5, 6 or many mixtures thereof, from 5 to 12% by weight of expanded perlite and from 2 to 15% by weight of waste pulp with containing from 70 to 99% by weight of fiber content;

Description

The invention relates to non-combustible asbestos-cement boards intended for use in building interiors.

It is known that conventional asbestos-cement boards and elements have, besides a number of positive properties, also some drawbacks, which include poor mechanical machinability and brittleness, relatively high bulk density and low fire resistance. These disadvantages prevent the wider use of asbestos-cement boards in some building applications. There is therefore a general need for non-combustible panels with good mechanical workability, suitable for extensive application in building structures not exposed to direct weathering. Due to the urgent requirements of fire protection, a fire-resistant, stable asbestos-cement element with increased porosity has been developed, allowing the escape of the bound water present at high temperatures without breaking the material and with good workability. These. fire protection elements produced using siliceous additives have very good fire protection properties; however, due to the lack of suitable interior panels, they are also used for other construction applications where their advantage is not fully utilized. Their disadvantage is the relatively high content of asbestos and the content of a certain proportion of economically demanding long-fiber asbestos. Hardly flammable, flexible asbestos-cement boards have also been developed, showing high flexibility in addition to good mechanical machinability, suitable as sheath material for sandwich panels and lightweight partition walls, for interior cladding and cladding of peripheral walls and the like. Their disadvantage is the lack of kraft pulp content as well as the lower class in terms of fire resistance.

The above-mentioned drawbacks eliminate and the desired properties have a non-combustible asbestos-cement board for interior use according to the invention, which consists in that the board contains from 38 to 78 wt. % Portland cement, from 15 to 35 wt. % of chrysotile asbestos of class 5, 6, or mixtures thereof, from 5 to

222 944 wt.% Expanded perlite and from 2 to 15 wt. % biowaste containing 70 - 99 wt. % fiber content.

An advantage of the non-combustible asbestos-cement sheet according to the invention is that it does not contain either long-fiber, economically demanding asbestos of high grade grades or scarce kraft grade requiring separate fiberizing while maintaining good fire resistance and mechanical workability. Another advantage of the board according to the invention is that it utilizes functionally, in terms of the technological process of forming the sheet, waste pulp, namely paper pulp, waste paper, cloth, or mixtures thereof, which are often hardly reusable products for papermaking. The advantage of use over the addition of pure kraft pulp, as in the aforementioned, low flammable, flexible asbestos-cement elements, is due to the economic impact and the fact that the pulp is generally a scarce material. The presence of highly fibrillated fibers in waste pulp, such as paper pulp or waste paper, allows energy savings for the grinding of fresh pulp. The highly fibrillated fiber fraction in the pulp waste, as well as the swollen, partially gelatinized fibers, improve the formation and cohesiveness of the wet carpet and promote the retention effects of other fiber components or additives and contribute to providing the necessary physico-mechanical properties of the product. The presence of inorganic non-fibrous constituents, such as, for example, kaolin, present in the papermaking sediment is not a problem. The use of expanded perlite as a non-fibrous component ensures good thermal engineering properties and mechanical machinability of the resulting board. The fire-resistant asbestos-cement slab according to the invention has the advantage of a reduced total amount of asbestos compared to fire-resistant, stable asbestos-cement slabs intended primarily for fire protection, which is desirable in view of the possibility of import restrictions and unfavorable health effects and from the beasts. Appropriate choice and balance of the individual components resulted in good workability of the starting mixtures on asbestos-cement machines and yield, as well as the required quality parameters, which besides the already mentioned include relatively low bulk density at very good strengths, thermal insulating properties etc.

222 944

The three production of a non-combustible asbestos-cement slab according to the invention is carried out, for example, by first preparing a pulp and asbestos slurry in a pulping plant, to which appropriate amounts of cement, expanded perlite and, if necessary, are introduced. additives including returned waste. The suspension obtained is dewatered in a conventional manner on a Hatsch molding machine. After curing for 28 days, the slabs are preferably dried in a double-sided oven. Surface protection can be carried out with both classical coatings, dispersion spraying and wallpapering, cutting and drilling can be done with conventional tools with reinforced tips. Products are resistant to mold and classified according to ČSN 73 0862 in category A - non-combustible ·

The properties of the material produced according to the invention are illustrated by the following examples.

Example 1

2.0 kg chrysotile asbestos # 6

4.9 kg of cement

0.8 kg of expanded perlite

0.25 kg waste pulp a.s.

The ingredients were mixed in water to a suspension of about 10%. The products drained on the laboratory filter device were pressed at a pressure of 1.0 MPa. After 28 days of wet deposition, the products exhibited a bulk density of 820 kg / m @ 2 and a flexural tensile strength of 10 MPa.

Example 2

112 kg chrysotile asbestos # 5

200 kg cement 57 kg expanded perlite 26 kg waste pulp a.s ·

The above components were mixed in water to a slurry of a final concentration of about 5% and formed on a Hatsch molding machine. After 28 days of wet deposition, the products exhibited a bulk density of 850 kg.m-2, a flexural strength in the direction perpendicular to the fibers of 10.7 MPa, in a direction parallel to the fibers 9MPa ·

Example 5 kg of chrysotile asbestos # 6

200 kg of cement 42 kg of expanded perlite 56 kg of waste pulp a.s.

222 944

The bulk density of the products obtained as in Example 2 was 800 kg.m ^, the flexural strength in the direction perpendicular to the fibers

11.5 ^and in the direction parallel to the fibers 9.7 IuPa.

The use of only less valuable asbestos and waste products from the paper industry without the addition of other expensive or scarce components, while maintaining flame retardancy, insulating properties and mechanical machinability, including the possibility of nailing or fastening with screws, prerequisites for mass production and wide application in all types of buildings wood of melts, single-family houses and cottages, for example as a honeycomb material of sandwich panels and lightweight partition walls, for the inner cladding of peripheral walls, soffits and interior wall claddings, for wind protection and the like.

Claims (1)

A non-combustible asbestos-cement panel for interior use, characterized in that it contains from 58 to 78 wt. % Portland cement, from 15 to 55 wt. % chrysotile asbestos of class 5, 6 or mixtures thereof, from 5 to 12 wt. % of expanded perlite and from 2 to 15% by weight of pulp waste containing 70-99% by weight of fiber portion.