Geologist, State of Wisconsin Department of Transportation, Madison, WI
Popouts in concrete bridge decks prompted an investigation into the reasons for such performance in relatively new construction projects. Certain stones usually reddish in color and belonging to a lithologic unit referred to as the superior group appeared to be responsible for the popout action. Conventional tests had not revealed any excessive values or unusual properties. Several area pits were examined, sampled, and tested by different methods. There were no specific series of tests that indicated the durability of aggregates used in this study, but an indication of high absorption to greater loss in soundness tests was detected. From testing results and past performance records, a recommendation was made to require individual stone counts to isolate the amount of the suspect aggregate. It was further recommended that a soundness loss of not more than 5% of the total specimen be allowed to conform with the “deleterious substances” section 501.3.6.4.3 of the current specification.
Paper ID: CCA10254J