Interstate 40 Western Loop Retaining Wall
Project Details
Location
Greensboro, North Carolina
Owner
North Carolina Department of Transportation (NCDOT)
General Contractor
Wall Designer
Lightweight Aggregate Supplier
Stalite Lightweight Aggregate
Description
The Interstate 40 Western Loop retaining wall was constructed as part of the NCDOT Greensboro Western Loop project. Located just north of West Vandalia Road near the intersection of West Vandalia and Groometown Road, the site presented geotechnical challenges including compressible soils and limited room for over-excavation.
Stalite expanded slate lightweight aggregate was specified as structural backfill behind the retaining wall to reduce lateral earth pressures and control settlement over weak subgrade soils. Its lower unit weight minimized loads on the wall while maintaining high shear strength for stability.
Material shipped from Stalite’s Aquadale, North Carolina plant met ASTM C330 (¾” to #4) gradation requirements and averaged approximately 53 lb/ft³ damp loose density at delivery. A total of 4,200 tons of lightweight aggregate was used on the project.
Compared to ordinary fill ranging from 100 to 130 lb/ft³, the lightweight aggregate provided a maximum compacted in-place density of approximately 62 lb/ft³ wet (59 lb/ft³ dry) with an internal angle of friction between 40° and 46°, delivering reduced wall loads and improved performance over compressible soils.
