Widespread failures of concrete basement foundations in Connecticut appear to be the result of oxidation of a particular mineral found in the aggregate from a Connecticut quarry, according to a 101-page report by University of Connecticut experts to the state Attorney General.

The report's conclusion is expressed in carefully hedged academic language: "A hypothesis is established: pyrrhotite in the aggregate oxidizes at the presence of water and oxidant (oxygen or ferric ions) which lead to the formation of expansive secondary mineral product such as ferrihydrite and the release of sulfate. The released sulfate promotes the reaction with aluminum containing phases in the cement (tricalcium aluminate (3CaO∙Al2O3)) and results in the formation of expansive and thus deleterious secondary minerals such as ettringite.

Read more >