Transite

The Transite, that is produced today, is a completely fireproof composite material and a non-asbestos product. [http://www.bnzmaterials.com/trans.html Transite HT] , and [http://www.bnzmaterials.com/trans1000.html Transite 1000] , are currently available fiber cement boards that contain no asbestos. Instead it contains crystalline silica which has been classified by The International Agency for Research on Cancer (IARC) as being carcinogenic to humans (Class 1). Crystalline silica is also known to cause Silicosis, a non-cancerous lung disease.

The use of asbestos to manufacture Transite was phased out in the 1980s. However prior Transite was made of 12-50% asbestos and cement, leading to its frequent use for such purposes as furnace flues, shingles, siding, 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, sanitary sewer drain piping, and HVAC ducts. Because cutting, breaking, and machining transite releases carcinogenic asbestos fibers into the air, its use has fallen out of favor.

Demolition of older buildings containing transite materials, particularly siding made from transite requires special precautions and disposal techniques to protect workers and the public.

Transite was available as early as 1929, as it was used for the skin of the 1929 Hollywood Bowl shell, which stood until the fall of 2003. As an acoustic material, however, transite has the additional problem that its cement binder continues to harden over an indefinite period of time, which can introduce harsh echoes.