Concrete expansion joint

A concrete expansion and contraction joint is provided comprising a hollow single piece longitudinal extruded member having a cross sectional configuration which resembles an arrow head with a relatively narrow upper stem portion. When the expansion joint is inserted into the fluid concrete aggregate, the V-shaped bottom of the arrow head structure moves aside any stones encountered in the concrete by the top of the arrow thereby facilitating installation. The top edges of the sides of the V-shape upon immersion in the concrete form locking anchors. Horizontal portions extending laterally on each side from the upper central stem portion of the joint to a point near the top of the V sides form flanges that provide channels which block downward water seepage at the joint.