EPP Grade Rings Provide Durable Solution on Stormwater Inlets

The Champaign-Urbana Mass Transit District boasts over 12 million riders annually. The University Avenue Terminal sees a constant flow of coach buses. Its concrete pavement is approximately five years old and had developed a problem with premature failure around stormwater inlets. The pavement surrounding three inlets had deteriorated and was replaced three years ago under warranty by the original contractor.

It was discovered that the repaired areas had sunk and new repairs were needed. During excavation of one inlet, the contractor found that the top two concrete grade adjustment rings were broken and only held together by the steel reinforcing wire. The extruded butyl rope typically used under the casting and between the concrete grade rings had been pushed out of the joints into the inlet. This was likely the primary cause of the failure. Similar findings were reported at the other two reconstructed inlets.

PRO-RING is manufactured from expanded poly­propylene (EPP), a lightweight, high-strength plastic that has an energy-­dissipating property.

Another method of construction had to be found: PRO-RING™ by Cretex Specialty Products. PRO-RING is manufactured from expanded polypropylene (EPP), a lightweight, high-strength plastic with an energy-dissipating property. It weighs 95% less than typical concrete grade rings, yet meets or exceeds AASHTO HS-25 loading and has excellent chemical resistance. Because it is installed using a construction adhesive/sealant, the use of the butyl rope was eliminated. All three of the inlets were adjusted with the Cretex PRO-RING and as of 2017, there have been no signs of pavement failure or settlement around the reconstructed inlets. WW

Cretex Specialty Products develops products for all your manhole sealing solutions. To learn more, visit www.cretexseals.com.