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.
2 Wheaton Center
08/2014 - 11/2015
Terry McDonald, Associate Principal
Zelina Johnson, Senior Associate I
Mike Naponelli, Senior Associate I