Abstract: Joints having utility in connecting together concrete reinforcing bars are improved by adding teeth to preselected interior side walls of the joint to increase the frictional engagement between the rebars and the joint. In a first embodiment, the joint is of oblong construction and includes a pair of flat, parallel walls and a pair of transversely spaced, opposing curved walls that interconnect the flat walls. Plural, parallel rows of elongate teeth are formed in the interior surfaces of the curved walls, and the teeth are normal to the plane of the flat walls. Each flat wall is apertured and receives a wedge that drives the rebars in the joint away from one another and into the teeth. In a second embodiment, the joint has an elongate "U" shape including a pair of transversely spaced flat walls interconnected by a curved wall and plural parallel rows of elongate teeth are formed in the interior surface of the curved wall.

Abstract: In joint for connecting reinforcing bars (5 and 5) in such a manner that the connecting end portions of the reinforcing bars are respectively inserted into the respective curved portions of a hollow metallic pipe (sleeeve 1) from the opposite sides thereof, and a wedge 6 is press-fitted into the area between the reinforcing bars from one of the wedge bores 4 and 4' to the other, a joint having a concave portions 8 and 8' on the inner surface of the curved wall 3 and 3' at the inner surface of the arc center of the pair of curved walls of the sleeve.