Recycled Materials as Backfill for Mechanically Stabilized Earth (MSE) Walls

Granular materials are often the product of construction operations, industrial operations, or dredging operations in rivers, ports, and harbors. Traditional sources of reinforced granular backfill in Mechanically Stabilized Earth (MSE) wall construction (e.g., from crushed rock quarries and gravel pits) can be costly and environmentally not desirable. The use of recycled materials sourced from construction, industrial, or dredging operations could be a potentially more economical and environmentally beneficial source of backfill material than traditional sources. The overall goal of this project was to facilitate use of RAP and RCA in reinforced backfills for MSE retaining wall construction.

In this study mechanical and hydraulic properties of RCA and RAP for use in Mechanically Stabilized Earth (MSE) walls were evaluated. Results show that compacted RAP and RCA provide competitive pull-out resistance for woven geotextiles and uniaxial geogrids compared to compacted natural granular materials. Construction of a structural fill containing RAP is recommended to be undertaken during summer to reduce the creep strain and creep rupture potential and improve performance of the fill.