This project included a very innovative design that is not used on a regular basis within the aviation industry. The existing runway pavement section, prior to the new reconstruction work, consisted of the following pavement section: seven-inch Thick ACC Overlay/six-inch Thick PCC Concrete/nine-inch Thick P-154 (Sand) Aggregate Base.
During the design, Benesch completed a preliminary design phase in which seven different pavement section alternatives were evaluated, ranging from a new minimal four-inch mill with new asphalt overlay to complete reconstructions starting from the subgrade up. The new pavement structure options costs were evaluated not only on initial cost, but also on a 20-year life cycle costs accounting for the routine maintenance needed on asphalt and concrete surfaced pavements. The final selected option was an economical, and ‘green’, solution formulated by Benesch which reutilized the majority of the existing pavement structure materials.
From the pavement section selected, Benesch ultimately designed the project to first mill off the top eight-inches of the existing pavement structure. The millings were then screened (to a required gradation) and stockpiled on-site for re-use during the project. Then, the remaining existing PCC concrete was rubblized and seated in order to create a granular base course out of the existing PCC pavement. A test section was performed during the rubblization process to ensure the size of the rubblized material met the project specifications. After the existing concrete was rubblized and seated, a two-inch thick leveling course of the screened millings was added on top of the rubblized base course. The millings leveling course was added as a layer that could be trimmed to grade by the contractor during preparation operations for concrete paving. The “trim-able” layer was designed and added since it is difficult to trim a rubblized concrete aggregate layer without pulling out larger pieces of the rubblized material. Last, following the completion of the two-inch screened milling layer, a new six-inch thick P-501 concrete surface layer was constructed.