Premature deterioration of concrete on Trunk Highway 169 near Hibbing, Minnesota, triggered an investigation to determine the potential cause of the distress. The deterioration manifested in the form of severe cracking and spalling in the top 75 mm (3 in.) of the pavement near the transverse joints. Investigation of cores obtained from locations near joints and midpanel indicated that the air void system in the top portion of the pavement was compromised initially (during construction) by nonuniform vibration across the depth of the concrete pavement and later by in-filling of the marginal air void system with secondary products. Absence of any evidence indicating the structural failure of the pavement or of the loadtransfer devices suggested that inferior concrete and poor construction practices were primarily responsible for the pavement failure.