a reinforcing bar connection for concrete construction utilizes a sleeve supporting internal spring washers having flexible inner edges which engage a bar inserted in the sleeve . the reinforced inner edges of the washers bite into the bar and grip the bar preventing withdrawal . the washers have openings which permit the sleeve to be filled with a hardenable matrix such as grout or resin . in a preferred form , shoulder forming wedge grooves are formed in ends of the sleeve . the connection may be used as a dowel socket , a continuity set , or as butt end - to - end bar splice for axially aligned bar of the same or different size . the connection provides not only high compressive and tensile strengths but also will provide the dynamic and / or fatigue characteristics to qualify as type 2 coupler approved for use in all united states earthquake zones .