A polystyrene cap with a removable top. When placed over asphalt impregnated expansion joint, the top section can be separated from the bottom section creating a 1/2″ x 1/2″ void on the surface of the concrete. Polysulfide rubber of Thiokol can be poured into the void on top of the remaining cap. The cap act as a barrier eliminating migration of chemical seepage to the surface of the concrete.
