pyritic sulfur content in backfill material 2

[PSUengineer1]

I am looking for opinions on what can happen to a concrete slab-on-grade foundation if back-fill material (sedimentary rock) contains high percentages of pyritic sulfur. Pointing to any reference material that I can read on the topic would be a great help.
Thanks.

 

[tolchijb]

Pyritic sulfur is extremely susceptible to oxidation and will break down into sulfuric acid and secondary sulfate crystals. As long as it is not exposed and there is no oxygen present it remains stable. However, if allowed to oxidize it will increase in volume and can cause so serious heaving and foundation problems. See below for a link.

Link

 

[Ron]

In addition, it can cause deterioration of concrete if in direct contact.

 

[dik]

A really bad material...

Dik