two single-span composite steel girder bridge, 208 x 40 roadway (structure numbers 52-435-289 and 52-435-288) as part of project IM90-2(134)59 PCN 4259, I-90 over East North Street in Pennington County;
two three-span composite prestressed concrete girder bridges, both 173.35 x 40 roadway, (structure numbers 08-230-130 and 08-230-131) as part of IM-90-6(37)281 PCN 1245, I-90 over a county road in Brule County.
The intent is to use low alkali Type I/II Portland cement with lower cement content and dense graded aggregate to achieve a compressive strength equal to conventional bridge deck concrete with fly ash and higher cement content. Bridge decks on both steel and prestressed concrete girders will be included in the research. This will be in conjunction with optimized gradation concrete for the decks.
It may be necessary to mitigate for ASR susceptible aggregates as some aggregates in South Dakota are known to be alkali-silica reactive (ASR). The reduced cement content mixes should have less shrinkage which should result in fewer cracks and increased protection for reinforcing steel from deicing chemicals. All the recommended procedures in the draft specifications for controlling concrete temperatures, slump, protection from evaporation and rapid water loss and curing will be adhered to. Surface texture will be cut into the hardened concrete on all decks after the curing period is over. Appropriate data will be collected to support Pooled Fund TPF-5(051) Construction of Crack-Free Concrete Bridge Decks.