Deterioration of residential concrete foundations: The role of pyrrhotite-bearing aggregate

The results showed that pyrrhotite and its oxidation products, such as ferrihydrite, goethite and sulfur, were present in or at the surface of the aggregates of the deteriorated concrete, suggesting the occurrence of pyrrhotite oxidation. Expansive secondary mineral formations (SMF) such as ettringite and thaumasite were also identified. The abundance of these SMFs, their spatial distribution in the open spaces together with their close association with matrix cracking suggest the cause of premature deterioration.