Abstract: The sections of concrete tubes or rings are connected end to end by means of a joint, and, in order to prevent aggregates and other undesirable materials to penetrate into the joint when a space is formed in the latter following climate modifications or other disturbances, there is disposed at the level of the joint, a ring of flexible material, which includes a flange made to remain pressed against the joint and to cover the latter permanently even if a space is produced in the joint. This ring is preferably fixed at one of the sections of tube and this ring may even be made of two interconnecting members.