Project Summary/Scope:
The Route 6/10 Interchange Reconstruction project is the largest design-build project in Rhode Island Department of Transportation (RIDOT) history. The total scope of the work involves the reconstruction of the entire Route 6 and 10 interchange within the existing highway right of way while replacing or removing the seven structurally deficient bridges within the project area.
Two of the flyover ramps have an existing 100-year-old brick sewer underlying the alignment of the ramp. The relocation and/or realignment of the existing utilities was determined to be not feasible. Ground improvement was determined to be a very costly and time-consuming solution.
Thus, the flyovers utilize a U-Wall system with polymer straps and polyester geogrid and ultra-lightweight foamed glass aggregate (UL-FGA) backfill. Exposed abutment heights are approximately 23 and 33 feet high. The adoption of UL-FGA lightweight fill solution protects the buried utilities against the weight of the embankment, satisfies the constraint of zero settlement of the sewer imposed by the utility owner, and provided cost and time savings to RIDOT.
Complementary Technologies Used: U-Wall MSE System
Alternate Technologies: Soil-mixed rigid inclusions, expanded polystyrene (geofoam), foamed concrete and expanded shale aggregate were considered. Alternate options were either not feasible or more costly and time-consuming than the UL-FGA option.
Performance Monitoring: N/A
Cost Information: $3M estimated cost savings over ground improvement option.
Case History Author/Submitter:
Theresa Andrejack Loux, Ph.D., P.E.
Chief Technical Officer
Aero Aggregates of North America LLC
717-574-5614
RIDOT Project Contact:
Deirdre Paiva, PMP
Rhode Island Department of Transportation
Providence, RI
Project Technical Paper: Loux, T.A., and Filshill, A. (2021). “Ultra-Lightweight Foamed Glass Aggregate as MSE Wall Backfill: Properties and Case Studies.” Geosynthetics 2021, Industrial Fabrics Association International, 22-25 February 2021, Virtual Event.
Also, white paper written by Deirdre Paiva and Anthony Palombo.
Date Case History Prepared: 11 March 2022
Case History Prepared By: Theresa Andrejack Loux, Ph.D., P.E.