As part of a redevelopment project in downtown Tampa, Florida, a large grain milling facility was moving operations from the downtown port to a new facility further down Tampa Bay.
To address the possibility of coastal flooding, the entire structure needed to be constructed above grade, including the 8′ tall unloading conveyor tunnels. The structure was designed to bear on a mat slab cast over thousands of auger cast piles. The unloading tunnels were only about 10% of each silos footprint, so the areas long side of the tunnels needed to be filled.
Due to the slipform construction, there was very limited access, so the backfill material around the tunnels needed to be pumpable. Flowable fill was an option, but is very heavy. The design build contractor identified cellular concrete as a potential backfill material, which could save nearly 1ksf of dead load off of the mat foundation.
CJGeo worked with the design builder to create a mix design that would minimize the amount of dead load on the foundation, while providing adequate support for the bin floor when fully loaded with grain. Over the course of a few weeks, CJGeo crews placed nearly 7200CY of cellular concrete to fill the silo bases up to flush with the top of the unloading tunnel walls. Rodbusters were able to start setting steel the day after completion of the final lift in each of the silos.