What is the maximum amount of pyrite that can be tolerated in a concrete aggregate? is there another acceptance test for aggregate containing pyrite than ASTM C 294? Do you know of any case in which pyrite was clearly identified as responsible for deterioration of concrete?
The Standard Specification for Concrete Aggregate, ASTM C 33 sets no limits on the amount of pyrite that can be allowed. We do not know of any standard acceptance test for aggregate other than ASTM C 294. Pyrites themselves, when near the surface of concrete, often deteriorate to cause minor popping of the surface and staining. Other than the staining and localized popping, however, there is ordinarily no deterioration of the concrete, and we are unaware of any instances of it ascribable to pyrites. There could, of course, be reason to set one's own limitation on the quantity of pyrite where it is important to minimize staining.