Rationale

The effects of oxidation of iron sulfides in aggregates on concrete durability are well known. At present, ASTM C294 does not properly warn of the risks of concrete expansion caused by oxidation of the iron sulfide minerals. Pyrrhotite, (Fe1-x S), is the second most abundant of the iron sulfides and is probably the least stable of the iron sulfides. The intent of this Work Item is to give appropriate consideration to differentiating between the different iron sulfides, to provide guidance for distinguishing the forms of iron sulfide and to warn of the possible harmful consequences of using such materials in concrete.