Abstract: A non-absorbent, compressible joint forming device fabricated from closed cell, low density polyethylene foam material and used in expansion or contraction joints and isolation joints of sidewalks, driveways, highways, runways, parking decks an other applications where concrete slabs are used, comprising: a retained base for allowing expansion, contraction, and isolation of said joints wherein said non-absorbent, compressible base material is retained in said construction application and a tear-off strip wherein frangible bridges across said material thickness spaced in a predetermined manner along the length of said joint forming system are the means whereby said retained base and said tear-off strip are held together during a construction application, and a non-absorbent reservoir for sealant deposition when said tear-off strip is removed.