Expansion joint system of a concrete slab arrangement, comprising an expansion joint reinforcement to be arranged between a first and a second concrete slab (1, 2), the expansion joint reinforcement comprising at least two local dowels (3)transferring loads perpendicular to the slab plane. The dowels comprise a dowel plate (4) and a casing part (5). The dowel plate (4) and the casing part (5) are attached to the concrete slabs on different sides of the joint. The casing part (5) prevents the dowel plate from adhering to the concrete slab and allows the dowel plate (4) to move inside the casing part and thus allows the movements of the slabs (1, 2) in the horizontal direction. The dowels (3) are installed alternately relative to the joint so that the casing parts (5) of the adjacent dowels (3) are always installed on different sides of the joint.