Expanded polystyrene is used for concrete block-outs of all shapes and sizes. Commonly used to block out bolt pockets in concrete slabs, footings for awnings and canopy posts and openings in concrete structures. TEP is lightweight but very strong making it well suited for the task.
For this precast concrete project in King George, VA the manufacturer needed to block out an irregular channel concrete corner posts for a sound wall being constructed along I-66 in Virginia. For the rectangular slots, they used steel tube just like they always have but for irregular slots they used nominal 2 pound density EPS, cut to shape in four foot sections. They wrapped the EPS block-outs in duct tape and greased them before use which allowed for a clean release from the concrete and multiple uses for each of the block-outs.