In the late 1980’s, managers and inventors associated with Protective Liner Systems developed and patented a cure-in-place glass-fiber bag which was manufactured to match the internal dimensions of the manhole or host structure to be rehabilitated. The glass-fiber bags were impregnated with epoxy resin, inserted in the structure, inflated and expanded with an internal bladder, then heat cured. The bladder was then removed and lateral and invert openings were cleared. That process formed a cured-in-place composite liner which bonded to the host structure. Drawbacks to the process were that it required extensive specialized equipment and presented potential for error in measurement of the host structure and in the manufacturing and installation of the bag. Also problems with the bag completely adhering to the manhole caused complications.
In 1989, a hand-applied composite process was developed which requires only minimal equipment for installation and eliminates the need for tedious measurement and precision bag manufacturing. All structures, regardless of size or shape, can be lined by the same process. We are still using this process today to rehabilitate hundreds of brick and concrete structures. We have named our process the PerpetuWall Composite Liner System.