Small introduction to bitumen

logo_smallGLAPOR cellular glass boards on flat roofs are generally installed with hot melt bitumen 85/25. At 200°C, it is enough liquid to poor on concrete or to allow dipping a cellular glass block in the liquid. In this way, cellular glass boards can be very well adhered on concrete or on a steel deck roof. The joints between the boards can be filled with the liquid bitumen to guarantee a vapour tight roof. On top of that, it is cheap and as a consequence hot melt bitumen will remain in the cellular glass world for a long time. Nevertheless, it has an IARC classification, “probably cancerogenic for humans” like cited hereunder.

imagesA- Occupational exposures to oxidized bitumens and their emissions during roofing The body of available data from cancer studies in humans points to an association between exposures to oxidized bitumens during roofing and lung cancer and tumours in the upper aerodigestive tract. In support of these findings, extracts and fume condensates of oxidized bitumens, which are used primarily in roofing applications, showed sufficient evidence of carcinogenicity in experimental animals. Taking these data together, the Working Group evaluated occupational exposures to oxidized bitumens and their emissions during roofing as “probably carcinogenic to humans” (Group 2A).

We are not surprised that the bitumen roofing world is represented by an organization Bitubel to defend its necessity for roofing. Belgium water proofing membranes based on bitumen are applied all over the world.

bitumenHindustan Petroleum has written a nice handbook about bitumen as an introduction. It is a residue of the fractional distillation of crude petroleum. Oxidized bitumen is obtained by blowing hot air into hot bitumen (180°C). This operation increases the softening point and lowers the penetration. This type of bitumen is used for the installation of GLAPOR cellular glass boards. Bitumen 85/25  (softening point 85°C/ 2.5mm penetration) and bitumen 110/30 (softening 110°C / 3 mm penetration) are the favorite types to be used with GLAPOR cellular glass boards.

Besides the health issues, bitumen is a combustible material which becomes dangerous at 250°C. For that reason, modified flame retardant bitumen can be produced by using fire retardant magnesium hydroxide delivered for example by Europiren. Magnesium hydroxide decomposes at 300 °C-330°C close above the ignition point of bitumen.  GLAPOR cellular glass roofs installed with this type of bitumen are a candidate for a FM approval.

Another way to avoid the fire and health risks during installation is to work with “cold bitumen” or bitumen emulsionBitumen emulsion is a free flowing liquid at ambient temperatures. Bitumen emulsion is a stable dispersion of fine globules of bitumen in continuous water phase. Dispersion is obtained by processing bitumen and water under controlled conditions through a colloidal mill together with selected additives.

PCI PECIMOR DK is a typical example of a cold emulsion and is advised for the  installation of GLAPOR cellular glass boards like previously posted. Nevertheless, we are interested in harmless alternatives.

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