SYMPOSIA PAPER Published: 01 January 1998

Use of Controlled Density Fill to Fill Underslab Void


During the removal of a portion of a warehouse slab for the United States Navy, a large void that was caused by water erosion was discovered. The void was created behind a concrete seawall by years of tidal and current action. Conventional granular backfill material was considered but was dismissed as being nearly impossible to install and compact. Controlled density fill (CDF) was proposed and accepted as an acceptable backfill method.

Access holes were drilled along the exterior of the warehouse to allow easy placement of the CDF. A bulkhead made from sandbags was installed in the void to prevent the CDF from flowing past the limit of approved work. The CDF was installed over a period of two days to lessen lateral pressure on the sand bag bulkhead and vertical pressure on the bottom of the void adjacent to the concrete seawall.

By using controlled density fill, the project was successfully completed quickly and at a fraction of the original estimated cost using conventional granular backfill materials and methods.

Author Information

Mason, TF
Lone Star Northwest, Inc., Seattle, WA
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Developed by Committee: D18
Pages: 210–212
DOI: 10.1520/STP13074S
ISBN-EB: 978-0-8031-5383-7
ISBN-13: 978-0-8031-2477-6