Abstract: The present invention generally relates to methods and apparatus for protecting a coupling that is disposable within a concrete structure. In one aspect, a cap for engaging a coupling of a cement coupler bar is provided. The cap includes a body having an engagement portion and a back portion, wherein the engagement portion is configured to engage the coupling of the cement coupler bar. Additionally, the cap includes a flexible tail having a first end and a second end, wherein the first end is attached to the back portion of the body. In another aspect, a method of using a protective cap with a coupling of a cement coupler bar is provided. In a further aspect, a coupler bar assembly for use in reinforcing a cement structure is provided.