Wheaton Center Apartments is a complex of six buildings and three parking garages built in the mid 1970’s. Due to severe deterioration and structural issues, the owner undertook a major $19 million rehabilitation to revitalize the complex. The three garages include: The Commuter Garage, Garage No. 1, and Garage No. 2. All three garages are two-level, conventionally reinforced cast-in-place flat slab construction supported by cast-in-place perimeter foundation walls and interior columns. A recreational deck with tennis courts and community areas are located on the roof level of Garage No. 1. The Commuter Garage provides parking for daily commuters serving the nearby Metra station. All three garages provide 700 parking spaces over approximately 265,000 square feet.

All elevated parking decks were badly deteriorated, especially on the bottom surfaces. Extensive repairs were performed to these decks, many of which had failed. We estimated that the extent of deterioration on bottom side to be over 24,000 square feet. The previous major repair work involved a completely new overlay with epoxy coated top bars; therefore, the topside concrete delamination was limited. In addition, the waterproofing membranes and expansion joints were passed their useful life and required replacement. The commuter garage had significant deterioration at the columns at expansion joints and thermal movement-induced damage at the stairwells.

Though petrographic analysis it was determined that carbonation from car exhaust had extended into the bottom steel reinforcing layers which may have caused the significant quantity of bottom side deterioration along with the “halo effect” or anodic ring effect around the perimeter of previous patches. The ICRI definition of anodic ring effect is a “corrosion process in which the steel reinforcement in concrete surrounding a repair area begins to corrode preferentially to reinforcement in the newly repaired area.” Other factors contributing to the deterioration were insufficient bar coverage at various locations, extremely high chloride levels and buried electrical conduits.