126' tall silos under construction
Post-tensioning tendons prior to stressing and cutting

Ethanol Plant Silos

Project Description 

As part of an ethanol plant in Texas, there were two silos constructed, 126 feet tall and 76 feet in diameter to hold corn prior to grinding and fermentation for the production of ethanol. The silos are fed by a grain elevator from a rail unloading depot dispensed to an adjacent grinding mill. Only 20 feet apart, the silos were simultaneously built using the slip-form method of construction.

STRUCTURAL TECHNOLOGIES/VSL provided assistance to the structural engineer, furnished post-tensioning materials, labor for strand installation, stressing and grouting, and technical support during the design phase and 24-hour, on-site technical assistance during the slip to assist in the placement of the tendons. The use of post-tensioning in the walls reduced the amount of concrete and rebar that was required and allowed the slip to proceed more efficiently since with a post-tensioned design less reinforcement is installed during the slip compared to a conventional rebar design. The reinforcement included horizontal post-tensioning in the walls, provided by 190 tendons using the VSL ECI 6-7 anchorage system and galvanized duct with 3 to 7-0.6” strands per tendon. The slip was completed in seven days with technical support on-site continuously during the duct and anchorage placement. Once the slip was completed, access to the tendons was gained using swing-stages supported off the top of the silos. The strand was installed into the ducts using a special suspended version of the strand pusher.