Patent attributes
An assembly creates annular voids in concrete around the distal end of cylindrical tubes. A cap has a flat top and a cylindrical, depending skirt. An annular, foam plug extends between the inside of the skirt and the outer diameter of the tube. The plug has an undeformed inner diameter smaller than an outer diameter of the tube to create an interference fit around the tube and keep concrete out when the cap is on the end of the tube. The plug has a radial thickness of 0.3 to 1 inch, and has an axial length of 1 to 3 inches, with a bottom of the plug located at a bottom of the skirt. The cap is glued to the end of the tube for pressure testing. After the tube is entrained in concrete, the cap and plug are removed to leave a void in the concrete surface.
