A Study of the Use of Ultra-Lightweight Foamed Glass Aggregate for Retaining and MSE Wall Backfill

Ultra-lightweight foamed glass aggregate (UL-FGA) is a sustainable choice lightweight fill and is manufactured across the United States. The manufacturing process uses curbside-collected (post-consumer) recycled glass as feedstock. The low density and high permeability of UL-FGA may be especially beneficial when used as retaining wall or mechanically stabilized earth (MSE) retaining wall backfill if there are soft soils, sensitive structures, or utilities present in the subsurface. Additionally, the use of UL-FGA as a lightweight backfill allows for the structural optimization of the wall itself including seismic loads. Details and considerations for using UL-FGA in traditional and MSE wall design are presented in this paper. Additionally, the implication of using a low density and highly frictional retaining wall backfill on lateral pressures is quantified for static and seismic conditions.