What is pyrite contamination?
Pyrite is a mineral found in various rock formations such as concrete. It is particularly sensitive to environmental changes. When in contact with humidity and oxygen, it can become oxidized, leading to a swelling in the landfill and pressing against concrete structures. This problem is inconveniently hard to predict.
How to identify pyrite contamination?
The first sign of pyrite contamination is the appearance of star or cross-shaped cracks in the ground and the foundation walls, as well as concrete slab swelling leading to “big bumps”. Cracks may also release a white powder commonly called efflorescence. The great pressure on concrete slabs can lead to cracks in the wall of a garage, or even floor unevenness in some cases. When contamination is addressed promptly, severe damage to foundation walls can be avoided.
Decontamination with FABexcavation
To ensure a proper decontamination, the concrete slab must be removed to replace the landfill rocks and debris with DB-certified crushed stone, conform to interior foundation standards. Foundation walls are then strengthened with steel plates, and cracks are repaired by epoxy or polyurethane injections. For additional security, it is recommended, whenever possible, to add a waterproof geotextile membrane between the landfill and the concrete slab. The decontamination repairs are completed by casting a new reinforced concrete slab on swell-proof landfill.
