Narragansett Bay Commission Rehabilitation of Large Diameter Brick Sewer with Geopolymer Mortar

The summer of 2018, the Narraganset Bay Commission (NBC) undertook their first large scale geopolymer mortar pipe rehab project as part of the Route 6 and 10 Interchange reconstruction in Providence, RI. This is part of a Rhode Island Department of Transportation (RI DOT) project to fully reconstruct the Route 6 and 10 approach ramps and elevated superstructure by 2020. The trenchless subcontractor rehabilitated 2,430 linear feet (LF) of brick pipe up to 60” diameter round and including vertical ellipses ranging 30”×45” to 38”×57”. This was done using spin cast geopolymer lining (SCGL) utilizing GeoSpray geopolymer mortar. SCGL provides a structurally independent, corrosion resistant new pipe in a pipe. Because many of the manholes were located in the middle of a 4-lane highway, maintenance and protection of traffic (MPT) played a critical part in the success of this project. Fortunately, SCGL requires a very small construction footprint, beneficial in dense traffic areas, and it does not require excavated insertion pits. The contractor completed all the rehabilitation in August 2018. This presentation will focus on the trenchless options considered, why NBC selected geopolymer mortar, construction challenges in the middle of a highway, and lessons learned.