Dynamic Characteristics of Lightweight Cellular Concrete

Lightweight cellular concrete has been utilized in many geotechnical applications including as the backfill in retaining walls, lightweight pavements, land slip repairs, bridge approach fills and to provide shock absorption in earthquake zones. The use of this material in seismic regions requires an understanding of its dynamic properties. In this study, five different mixes of lightweight cellular concrete, with varying unit weights were tested in a cyclic simple shear apparatus. The samples were subjected to four different consolidation pressures followed by a series of fifteen strain-controlled undrained sinusoidal cyclic loads. The cyclic strains were varied from 0.08% to 1.0% double amplitude shear strains. From the results obtained, the maximum shear modulus was found to increase as the dry unit weight of the material decreased and as the consolidation pressure increased. The damping ratio was found to decrease with increasing shear strain until a threshold shear strain was reached beyond which the damping ratio increased with an increase in the shear strain. This threshold shear strain ranged from 0.25% to 0.35% for the specimens tested.