Cores from this sampling site were extracted from US 20, west bound. This pavement was placed using IDOT concrete Mix 1 containing a class C fly ash. Cores from mile 124 (Core 18) were extracted from a short segment that was closed to traffic and not salted for at least the first year. This pavement exhibits no evidence of distress and led to speculation that deicing salts may be significant in the degradation . In contrast, specimens from Mile 125.55 (Core 19) are severely damaged, showing longitudinal cracking along vibrator paths, cracks paralleling transverse joints, and map cracking. The distress was first noted in 1990, about four years after placement, and the crack density appears to decrease with distance from edges and joints.