MICROSTRUCTURAL INVESTIGATION OF SEVERE DISTRESS IN A CRUSHED CONCRETE BASE

A parking lot was constructed on a crushed concrete base overlying a l ime-stabilized subgrade. Despite adequate thickness of the subgrade an d base, and having followed the construction codes and engineering spe cifications, within a very short period of time the base developed sev ere distress in the form of massive heaving and rutting. Microstructur al investigation revealed intense sulfate attack, resulting from conta mination of the crushed concrete stockpile with a calcium sulfate indu strial waste. Gypsum, ettringite, and thaumasite were identified as th e principal deterioration products. (C) 1998 Elsevier Science Ltd.