Cyclically Induced Deformations in Lightweight Cellular Concrete Backfilled Retaining Structures

Application of lightweight cellular concrete (LCC) materials are increasingly popular in major projects due to their multiple benefits including significantly low surcharge loads. While implementing agencies have shown their interest in using such materials in backfills of mechanically stabilized earth (MSE) retaining walls, the investigation is limited to the determination of the static properties. However, with the increased use of LCC retaining walls in seismically active regions, it is necessary to understand the seismic performance of these structures. In this study, a 1.8 × 1.2 × 1.2 m block of LCC retaining wall with unit weight of approximately 4 kN/m³, reinforced at the mid-height with a geo-grid layer, was subjected to seismic loading of different amplitudes and frequencies on a shake table to evaluate the response of the wall and geo-grid to seismic loading. Numerous accelerometers and strain gauges were installed at different heights to evaluate the deformation of the LCC block at different depths and relative to the geo-grid. To evaluate the effect of surcharge load and simulate different layers, the blocks were separately loaded seismically at the surcharge stresses equivalent to the surcharge load of 3 and 3.7 m, i.e., a total retaining wall height of 4.2 and 4.9 m, respectively. Specifically, the LCC retaining wall was subjected to a series of sinusoidal cyclic loads with amplitudes ranging from 0.1 to 0.2 g and frequencies of 2 and 3 Hz. Additionally, the ground motions recorded from the 1994 Northridge Earthquake were also applied to the model. Observations of the model during the shake table testing did not indicate the formation of any fractures within the LCC retaining wall. The results obtained from accelerometers and strain gauges indicated that the LCC retaining wall moved monolithically, meaning no observable differences were noted in the displacements of the LCC material relative to the geo-grid.