Only a year after installing a triple 60-inch-diameter reinforced concrete equalizer pipe under 30-feet of cover at Mitchell Interchange on I-94, the Wisconsin Department of Transportation found that the pipe already needed to be relined due to structural cracks.
After considering their options, the Wisconsin DOT chose HEL-COR® pipe by Contech Engineered Solutions. This product was significantly more economical than that of two alternative products considered. HEL-COR offers a wide range of wall thicknesses, corrugations, diameters and pipe section lengths to meet any specific job requirement.
For this project, the Wisconsin DOT specified 54-inch diameter, Aluminized Steel Type 2 (ALT2), 5-inch x 1-inch HEL-COR pipe instead of solid-wall HDPE.
Benefits of HEL-COR® pipe include a proven service life that can exceed 100 years with proper specification, sustainability from recycled material, strength, flexibility, versatility and lightweight material. By using homogenous material, HEL-COR eliminates failures due to stress cracks, shrinkage cracks and air voids.
In this project, 10 c internal expanding bands were used with flat gaskets. During install, the pipe was stagegrouted in three lifts, and had two grout plugs in each piece of 20-feet pipe length.
The Wisconsin DOT also chose to further protect the pipe by adding zinc chromate paint to the pipe exterior (the yellow coating on the pipe in the top photo). The purpose of this extra protection was to protect the aluminized coating from the flowable fill during the curing process.
The Contractor was able to perform this reline project in just seven days without disruption to traffic.