Asbestos Cement Products and Structural Components
Asbestos Cement Products and Structural Components
According to the method used in forming them, asbestos cement products are divided into sheet products (corrugated, flat, or special-design) and pipe products.
Before the 1930’s the basic type of sheet products manufactured in the USSR were pressed roofing shingles (asbestos slate), 40 x 40 cm in size and 4 mm thick. During these years the mass production of corrugated roofing sheets (wavy and semiwavy) in larger sizes was also begun. By the mid-1960’s in the USSR approximately 90 percent of the total output of sheet asbestos cement consisted of ordinary wavy sheets; the production of more economical large-scale sheets has also been expanded (see Table 1).
Semiwavy sheets, in which wave-like parts alternate with flat parts, also have the same sizes, but because of technical difficulties their output is insignificant.
Flat facing-sheets are classed as pressed sheets (possessing
|Table 1. Characteristics of corrugated wavy sheets produced in the USSR, 1968|
|Type of sheet||Length (cm)||Width (cm)||Thickness (mm)||Span (to be covered (cm)||Class of sheets||Basic purpose|
|VO ......||120||67.8||5.5||to 55||Small-scale||Top-story roofing of apartment houses and public buildings|
|Medium-scale Medium-scale||Same uses as VO Walls of factories and apartment houses|
|UV-6 ......||175–250||112.5||6.0||to 150 (walls—240)||Roofs and walls of apartment houses, public buildings, and factories|
|UV-7.5 ......||175||112.5||7.5||to 150 (walls—240)|
increased strength) and nonpressed sheets. They are produced in their natural gray color; they may also be dyed or textured. Sheet length ranges up to 2.8 m, width to 1.6 m, and thickness from 4 to 10 mm. These sheets are used for the interior finishing of auxiliary areas in apartment houses and public buildings, for coating panels, for installations in bathrooms and other sanitary facilities, and as safety enclosures for balconies, stairways, and so on.
Among the special-design products are the following: ventilation ducts, with either rectangular or round cross sections, with a socket at one end or without sockets; semicylinders for protecting the thermal insulating layer of pipes from mechanical damage; double-curved sheets for conveyor galleries; arched elements for building summer pavilions at tourist areas, Pioneer camps, and so on; and water-protective covers, used in underground subway installations to ensure the waterproofing capacity of the load-bearing structural components of roofs.
Pipe products are as follows: pressure pipes (water pipelines), nonpressure pipes, gas pipelines, and casing pipes (see Table 2). Pressure pipes and couplings are designed for an operational hydraulic pressure of 0.3, 0.6, 0.9, and 1.2 meganewtons (MN) per m2 (1 MN/m2 ≈ 10 kilograms-force per cm2).
|Table 2. Dimensions of the asbestos cement pipe produced in the USSR, 1968|
|Use||Internal diameter (mm)||Length (mm)||Thickness of walls (mm)|
|Pressure pipes (water conduit)||50–456||2,950–6,000||12–56|
Pressure pipes (water pipelines) designed for 0.3 and 0.6 MN/m2 are joined by asbestos cement couplings. For pressure pipes designed for 0.9 and 1.2 MN/m2, cast-iron couplings are used. The joints are sealed by rubber packing rings.
Asbestos cement structural components are manufactured from sheet asbestos cement, thermal-insulating materials, and asbestos cement, using wooden or metallic elements for the framework. In flooring structural components asbestos cement sheets are bonded together by screws, rivets, or by glue-type adhesives. Among such structural components are heated slabs (usually made with mineral felt) of the AP type (asbestos cement flooring), used for insulated covering of industrial buildings; the width of such slabs is 50 cm, and the covering span ranges up to 3 m. In slabs of the AS type (asbestos cement composite) the sheets are bonded together by a cement-asbestos mastic in a damp, unhardened state.
Monolithic structural components (slabs and panels) are manufactured from two flat sheets, bonded together by a layer of heating material (usually a foam layer). The thickness of the slabs and panels ranges from 60 to 80 mm, which allows them to be used in covering 3-meter spans. The most widespread structural components of the framework type are slabs and panels of flat asbestos cement sheets, bonded to the framework by adhesives or by screws. For the framework, asbestos cement bars are used as well as molded elements made of asbestos cement, wood, or metal. The width of the slabs ranges from 1.2 to 1.5 m, and the covered spans extend from 3 to 6 m.
REFERENCESPitskel’, L. N. Asbestotsementnye lotkovye plity. Moscow-Leningrad, 1952.
Sherman, L. N., V. I. Ovsiankin, and P. M. Frenkel’. Ograzhdaiushchie konstruktsii iz asbestotsementnykh listov dlia promyshlennykh zdanii. Moscow, 1952.
Blokh, G. S., and A. N. Litvinov. Asbestotsementnye materialy i konstruktsii i ikh ekspluatatsionnye kachestva. Moscow, 1964.
L. N. PITSKEL’