Secured Entrance to the Pentagon
Project Details
Location
Arlington, Virginia
Owner
U.S. Department of Defense
Designer
Geotechnical Engineer
MACTEC
Contractor
Facchina Construction
Lightweight Aggregate Supplier
Stalite Lightweight Aggregate
Description
The Secured Entrance to the Pentagon was constructed as part of the Pentagon Secure Bypass (PSB), a $25-million design-build project within the broader Pentagon Renovation Program. The work included relocation of a major highway, new site roads, parking areas, retaining walls, and three bridges to improve traffic flow and strengthen perimeter security.
The entrance alignment crossed compressible clay soils up to 15 feet thick. Testing indicated that using conventional 110 pcf fill would result in approximately 15 inches of total consolidation with an estimated consolidation period exceeding 180 days, well beyond the project’s fast-track schedule.
To address this challenge, the geotechnical engineer recommended replacing normal weight fill with rotary kiln–produced lightweight aggregate conforming to ASTM C330. By incorporating Stalite Lightweight Aggregate, the team reduced total estimated consolidation from 15 inches to approximately 6 inches and shortened the consolidation period to roughly 60 days.
The specified material provided a maximum dry density of 65 lb/ft³, delivered moist density of approximately 52 lb/ft³, and an internal angle of friction exceeding 40 degrees. Approximately 10,000 tons of Stalite lightweight aggregate were supplied through a Virginia terminal, with placement rates often exceeding 500 tons per day.
The project demonstrates how lightweight aggregate can significantly reduce settlement, accelerate schedules, and enhance long-term performance in critical transportation and security infrastructure applications.
