Patent ID: 8066931

Claim:
A method for manufacturing a lined concrete pipe comprised of an outer concrete layer and an inner liner layer containing a further material which forms a greater density inner surface liner, said method comprising: providing an outer mould part and a core, a space formed between the outer mould part and the core having a shape of the lined concrete pipe, the core being movable upwardly through the outer mould part; providing a vibrator within the core, feeding concrete to the space formed between the outer mould part and the core as the core moves upwardly within the outer mould part for filling the space with concrete, providing the core with an applicator comprising one or more supply openings positioned for delivering the further material below the concrete supplied to the space, vibrating the concrete filling the space between the outer mould part and the core for maintaining the concrete in a fluid phase as the concrete is filling the space while simultaneously supplying the further material through the supply openings of the applicator for merging and diffusing the further material into the adjacent fluidized concrete, and at least partially rotating the applicator and the core during delivery of the concrete and further material for merging and diffusing the further material into the concrete adjacent the applicator to provide a sliding transition from the concrete and out to the further material, forming a mutually denser structural liner with a tight bond, the liner integrating together the concrete and further material, thereby forming an integral liner with the concrete pipe, providing a greater density surface on at least a portion of an inner surface of the concrete pipe; and, delivering the further material for applying an inner layer to a bottom ring and/or a top ring and then applying said ring or rings to the core and the outer mould part.