Abstract: A device for joining two concrete members together, such as concrete tunnel or shaft lining segments (1, 2) includes at least one elastic female member (6) anchored in one of the segments and at least one elastic male member (7) anchored in the other of the segment to be joined. The female members (6) are provided with recesses (6A) to receive heads (7A) of the male members (7), each female member (6) being slotted at 6B to receive a respective web (7B) of the male members (7) and is undercut at 6C to receive the head (7A). At least one of the male and female members has a sloping engagement face (8, 9) to provide wedging action by acting to draw the head of the male member further into the female member as the web of the male member is moved along the slot.