Joint Movement between Face of Abutment and Slab End 1

Deck Slab seats on the top of prestressed girders. Slab is connected to the girders with some projected bars from the girders (R bars in TX girders). Girders are placed over Elastomeric Bearing. Now, my concern is how the movement (expansion or shrinkage) occur in the joint? Only the slab moves over girder or whole slab and girder moves together at the joint during expansion or shrinkage?