Foamed glass aggregates (FGAs) are an emerging material in the US for use as a lightweight structural backfill. Manufactured from recycled glass powder mixed with a foaming agent, FGAs are considered a sustainable solution with advantageous engineering properties noted
throughout the literature. For load-bearing applications, their long-term deformation behavior under typical, in-service static design loads is not as well understood, nor is its impact on shear strength. To address this gap in knowledge, the Federal Highway Administration conducted
long-term (28-day) compression and direct shear tests on two different FGAs: one manufactured through a wet foaming process (FGA-1) and the other through a dry process (FGA-2). The compression tests were performed on both compacted and uncompacted specimens under 82.7 kPa of applied pressure in a large-scale direct shear (LSDS) device used as a consolidometer; both dry and submerged conditions were evaluated for the compacted specimens. LSDS tests were then conducted immediately after the 28-day compression, as well as after a short consolidation phase. The experimental program also included sieve analysis, relative density, absorption, and aggregate imaging.