A duct system for profiled post-tendon construction has a first duct, a second duct and a third duct joined together in end-to-end relationship. The first and third ducts are of one type of polymeric material. The second duct is of a different type of polymeric material. The second duct has a parabolic curvature while the first and third ducts are generally straight. The second duct has a cross-sectional configuration that is identical to the cross-sectional configuration of the first and third ducts.