Large-Scale Testing to Evaluate Lightweight Cellular Concrete Backfill behind MSE and Cantilever Walls

Lightweight Cellular Concrete (LCC), with a unit weight of 4.7 kN/m3, induces significantly less vertical and active earth pressures than conventional soil backfill. Unfortunately, there is relatively little information to guide engineers in designing retaining walls using LCC backfills. To provide basic information on failure mechanisms and pullout resistance for these structures, a series of large-scale tests has been performed. Surcharge pressure was applied to the surface of the LCC behind walls that were 3 m tall and 3 m. Tests were performed with both cantilever walls with unreinforced LCC and MSE wall panels with LCC reinforced with steel reinforcing. Comparison tests were conducted with and without a retaining wall. Without a wall, brittle failure was induced. But with reinforcement, surcharge pressures increased, and failure was ductile. Surcharge pressures at failure were consistent with Rankine theory using a back-calculated friction angle of 348 and cohesion of about 72 kPa. Pullout tests defined F* vs. vertical stress for LCC.