What is pyrite?
Pyrite has been here for thousands of years. It is a common mineral found in the crushed stones used for backfill. Therefore, there is pyrite underneath the concrete slabs of basements and garages.
If the backfill is composed of friable stones, the pyrite inside could damage the concrete slab and the foundation.
The problem
The crushed stones that builders put underneath the concrete slabs are normally of good quality. Therefore, pyrite will not cause damages for the majority of the buildings. The gravel coming from certain quarries of the South-Shore and East of Montreal is sometimes of poor quality and has a swelling potential. Many properties in these areas (and elsewhere in the Montreal area) are or will be damaged. For more information, see Swelling due to pyrite.
Normal basement
Damaged basement due to pyrite
Vermiculite (zonolite) and Asbestos |
What is vermiculite (zonolite)? (source Health Canada)
In its natural states, vermiculite (zonolite) looks like mica. At high temperature, it expands to about eight or twelve times its initial volume, and becomes a lightweight material ideal for, among other things, insulation in attics.
The dangerous mineral containing asbestos was extracted from the Libby Mine in Montana (USA) between 1920 and 1990 and sold commercially in Canada under several trademarks, including Zonolite. Products from the Libby Mine were less frequently used beginning in the mid-eighties, and have not been available in Canada since about 1995.
The Problem
Health Canada published a notice in the spring of 2004 concerning vermiculite insulation, frequently found in residential attics. Some vermiculite insulation contains small quantities of asbestos fibres that can be harmful to health if disturbed by maintenance, renovation or demolition.
For more information, see Vermiculite (zonolite) and asbestos.
Going on..................................... |
