Patents Examined by Karen Aflergut
  • Patent number: 5051223
    Abstract: A concrete pipe is produced by introducing a wet concrete mass into a pipe form to produce a cylindrical mass having an inner wall, compacting the cylindrical concrete mass by applying pressing rollers to the inner wall, smoothing the inner wall of the compacted cylindrical concrete mass, and applying a liquid impregnation medium to the inner wall under pressure after the concrete mass has been compacted, the inner wall has been partially smoothed and the concrete mass is still damp. The pressure is sufficient to cause the impregnation medium to permeate the damp concrete mass to a depth of at least 10 mm.
    Type: Grant
    Filed: September 11, 1989
    Date of Patent: September 24, 1991
    Inventor: Gregor Kern