Bubbling during the curing process of spray-on epoxy products can be observed in the photo of Manhole Station 30. This type of bubbling of spray-on epoxy products can damage the concrete structure of the manhole when the expansion of the spray-on epoxy causes concrete swelling. Further examples of major bubbling and failure can be seen in Manholes 32, 33, 34 and 36.
This is just a representative sample of the visible failures of spray-on epoxy products. Another Denver manhole, designated MH 41, is located in a residential backyard and has major failures of spray-on epoxy. Each photo shows substantial failure of spray-on epoxy products, necessitating repeated applications for proper rehabilitation. Each additional application runs the risk of failure, and further deterioration of the manhole. Furthermore, failed rehabilitation through the use of spray-on epoxies adds to the expenditure of greater resources such as time, money and water.