What Is Necessary For Manhole Rehabilitation Success? Correct Application, Use Of Manhole Rehab Technologies

By Gerhard “Gerry” P. Muenchmeyer, P.E., NASSCO Technical Director | October 2011, Vol. 66 No. 10

Haessig: Because our product is a mechanical compression type seal, it does not bond to the manhole at all and also does not provide any structural strength. The purpose of the chimney seal is to provide a flexible, watertight seal between the manhole frame casting and the top of the manhole cone or corbel to prevent inflow.

Kiest: Because our liner is thermo-set resin based, we have options for various resin systems, i.e. epoxy, polyester, vinylester and silicate. Polyester is the most user friendly resin and is the most economical. Although polyester resin may mechanically lock into cracks and voids, it does not chemically bond to the host structure. However, our epoxy system is designed to mechanically and chemically bond to the host structure and our inflation bladder provides constant pressure forcing the liquid resin against and into the structure walls providing a superior bond.

Johnson: All the Sprayroq products bond to properly-prepared substrate. In structural applications of SprayWall, we know we are getting adhesion but the ASTM 1216-07 design guide does not assume an adhesive bond to the substrate for its thickness calculation for either partial or full deterioration. Our adhesion capability gives further conservativeness to the design.

Warren: Our product forms a tenacious bond to both porous and non-porous substrates, usually resulting in the breaking of the concrete/brick, or glue on the dolly before the test is complete. We can apply to damp surfaces as well as dry.

One of the most important aspects of manhole rehabilitation is the testing and inspection performed during all phases of the application process. A performance based specification will typically contain specific language about quality assurance and testing of the installed product. Quality assurance requirements are usually expressed in measureable terms, and therefore should be measured by applying industry standard test procedures before the product is accepted by the customer. The specifications will define the end product or deliverable that is required by the contract documents based on inspection and test results. Testing during and after product installation may include dry and wet film thickness testing, holiday or spark testing, adhesion testing, pre-installation substrate testing as well as visual inspection of the structure before and after coating or lining application.

Have product failures occurred and, if so, what were the cause and remedies?

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