Working to improve Pennsylvania's bridges
In September of 2008, Industry engaged the Pennsylvania Department of Transportation in a conversation regarding consideration of a bridge deck concrete that would be an improvement to the current AAA specification. Two primary focus areas were targeted to improve performance–reduce shrinkage potentional and ehanced permeability characteristics. To accomplish these objectives, Industry undertook the AAAP initiative. AAAP concrete will utilize a reduced cement paste content and require the use of supplementary cementitious materials (SCM). In addition to enhancing performance, a secondary objective was to design a concrete mix that could be readily produced by ready mixed concrete firms across the Commonwealth.
Following the intitial discussions with PennDOT, Industry conducted extensive research into the current practice for High Performance Bridge Deck concrete (HPC). A mix design evaluation program was outlined and research conducted to investigate the performance of AAAP made with representative materials (cement, SCM, aggregates, and admixtures) available across Pennsylvania. Base upon those results, a special provision specification was developed with the assistance of PennDOT. The results of the mix design program were shared with all the PennDOT Engineering Districts and trial field projects were selected. Ten projects were placed from September 2009 thru October 2010. Comparison testing between AAAP and AAA was conducted on each of these projects. Shrinkage potential was evaluated based upon the field test results.