Compression Index and Small Strain Stiffness of Six Coal Bottom Ashes in South Korea

Abstract

This study investigates the small strain stiffness (Gmax) of six coal bottom ashes in South Korea. One-dimensional compression tests using an instrumented oedometer cell were performed to measure the shear wave velocity (Vs), and the compression indices (Cc) of the six different bottom ashes were also explored in this study. The results demonstrate that, at low confinement, the Cc of bottom ashes are comparable to that of sand under a similar void ratio. However, at high confinement, the bottom ash shows very high Cc compared to sand due to the crushability of the weak and porous bottom ash particles upon confinement. The variations of α and β, which are Vs parameters (i.e., Vs = α (σ′m/1 kPa)β), with different Cc values of the tested bottom ashes are consistent with the existing empirical relationship. The Gmax of tested bottom ashes can be adequately captured by the existing Gmax estimating formula for angular sand, indicating that the Gmax of bottom ash is highly comparable to that of sand with a similar void ratio and confining stress.