Abstract: In a concrete-wrapped pipe having an inner water-impermeable resinous coating, the concrete wrapping is formed with a continuous inner portion covering the resinous coating and a helically slotted outer portion, the helical slot extending at least to the depth of a mesh reinforcement embedded in the concrete. The structure is characterized by the fact that the inner portion of the concrete wrapping is formed with one or more helically extending zones of reduced compressive strength, radially aligned with the helical slot or slots in the outer portion. The helical configuration breaks the continuityof the concrete wrapping in the longitudinal direction of the pipe and, even with pipe of relatively large diameter, enables the wrapping to accommodate limited bending of the pipe.

Abstract: In a concrete-wrapped pipe having an inner water-impermeable resinous coating, the concrete wrapping is formed with a continuous inner portion covering the resinous coating and a helically slotted outer portion, the helical slot extending at least to the depth of a mesh reinforcement embedded in the concrete. The structure is characterized by the fact that the inner portion of the concrete wrapping is formed with one or more helically extending zones of reduced compressive strength, radially aligned with the helical slot or slots in the outer portion. The helical configuration breaks the continuity of the concrete wrapping in the longitudinal direction of the pipe and, even with pipe of relatively large diameter, enables the wrapping to accommodate limited bending of the pipe.