Transite originated as a

brand A brand is a name, term, design, symbol or any other feature that distinguishes one seller's good or service from those of other sellers. Brands are used in business, marketing, and advertising for recognition and, importantly, to create an ...

that

Johns Manville Johns Manville is an American company based in Denver, Colorado, that manufactures insulation, roofing materials and engineered products. For much of the 20th century, the then-titled Johns-Manville Corporation was the global leader in the ...

, an American company, created in 1929 for a line of

asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixe ...

products, including boards and pipes. In time it became a generic term for other companies' similar asbestos-cement products, and later an even more generic term for a hard, fireproof

composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...

, fibre cement boards, typically used in wall construction. It can also be found in insulation, siding, roof gutters, and cement wallboard. The more prevalent transite found in wall construction and roofing tiles for example, will last anywhere from 50 years to over 100 years. The use of asbestos, a proven carcinogen, to manufacture transite was phased out in the 1980s. It was replaced by crystalline silica, which the

International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...

has classified as being carcinogenic to humans (Class 1). Crystalline silica is also known to cause

silicosis Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. It is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis. Silic ...

, a non-cancerous lung disease.

Historic

Originally, transite had between 12-50% of asbestos fiber added to a cement base to provide

tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials ...

(similar to the

rebar Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. ...

reinforced concrete Reinforced concrete (RC), also called reinforced cement concrete (RCC) and ferroconcrete, is a composite material in which concrete's relatively low ultimate tensile strength, tensile strength and ductility are compensated for by the inclusion ...

), and other materials. It was frequently used for such purposes as furnace flues, roof shingles, siding,

soffit A soffit is an exterior or interior architectural feature, generally the horizontal, aloft underside of any construction element. Its archetypal form, sometimes incorporating or implying the projection of beams, is the underside of eaves (t ...

and

fascia A fascia (; plural fasciae or fascias; adjective fascial; from Latin: "band") is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches to, stabilizes, encloses, and separates muscles and other internal organs ...

panels, and wallboard for areas where fire retardancy is particularly important. It was also used in walk-in coolers made in large supermarkets in the 1960s, 1970s and even the 1980s. Other uses included roof drain piping, water piping, sanitary sewer drain piping, laboratory fume hood panels, ceiling tiles, landscape edging, and HVAC ducts. Because cutting, breaking, and machining asbestos-containing transite releases

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...

ic asbestos fibers into the air, its use has fallen out of favor. Despite asbestos-containing transite being phased out, it is still not banned in the United States; some 230,000 deaths have been attributed to it. Demolition of older buildings containing transite materials, particularly siding made from transite, requires special precautions and disposal techniques to protect workers and the public.

Today

The transite that is produced today is made without asbestos. Transite HT and Transite 1000 are currently available fiber cement boards that contain crystalline silica, which the

has classified as being carcinogenic to humans (Class 1). Crystalline silica is also known to cause

, a non-cancerous lung disease.

References

{{reflist Composite materials

Historic

Today

See also

References