- A large parking lot was constructed on a crushed concrete base overlying a lime-stabilized subgrade. Despite adequate thickness of the subgrade and base, and having followed the construction codes and engineering specifications, within a very short period of time the base developed severe distress in the form of massive heaving and rutting. Microstructural investigation revealed intense sulfate attack, resulting from contamination of the crushed concrete stockpile with acalcium sulfate industrial waste. Gypsum, ettringite, and thaumasite were identified as the principal deterioration products. 1998 Elsevier Science Ltd.