Pyrite removal / contaminated backfill

Symptoms and causes

Cracking or fractured garage and basement foundations walls, bulging floors and whitish particles often indicate a pyrite problem. Lab tests can show if any (and how much) pyrite-bearing rock is actually present.

If pyrite is present in rock that is used as fill beneath a concrete floor or even occasionally in the concrete of the foundation itself, it will oxidize on contact with moisture and oxygen. This oxidation generates sulphuric acid, a substance that causes rock to burst and fill to swell. The process of expansion places enormous pressure on overlying concrete and will eventually damage it.

The same pyrite removal technique is also employed to remove fill contaminated with such substances as heating oil.

The solution

Any existing damaged concrete must be crushed in such and the stone removed from the contaminated fill.

Bisson Expert uses miniature excavation equipment to maximize the effectiveness of our operations and to ensure total safety.

New fill using quality-controlled stones is spread and compacted and then a new floor is poured.