Concrete block-outs made of expanded polystyrene are common in the construction industry. They are lightweight, economical, and relatively easy to remove after the concrete is set. Whether being used to create a bolt pocket or anchors to secure an awning or canopy EPS is the material of choice among contractors.
These block-outs, used on a project in Memphis, TN, were made from
nominal 1 lb density EPS. They were set in place and anchored prior to
the concrete being installed. After the concrete set up, the steel plate
and 2x4s were disconnected and the EPS was removed.