Material characterization of components and assembled behavior of a composite liner for rehabilitation of cast iron pressure pipes

Work is underway to determine the stability limit states for a cast in place composite liner system used to repair cast iron pressure water pipes. To establish its performance in bridging ring fractures, perforations, and other failures in the cast iron “host” pipe, it is important that the material characteristics of this composite liner be determined. This study characterizes the mechanical properties of this liner in both the longitudinal and circumferential directions, and develops a method to achieve this goal. A technique is developed to form the liner from its individual components and prepare coupons with end tabs. Test results for coupons oriented parallel to the axis of the pipe (i.e., in the longitudinal direction) agree well with those obtained from coupons cut from a liner exhumed from an actual field installation. Since the coupons formed in the laboratory are flat, the same technique is used to test the liner in the hoop (or circumferential) direction. Tensile strength and stiffness in the hoop direction are 45% higher than that in the longitudinal direction. Tests performed on the individual components of the liner are also reported, and these explain the bilinear stress–strain response. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers