Effect of the bottom ash content on the liquefaction resistance and cyclic degradation of pond ash under different dynamic loading conditions

Abstract

Pond ash has been used in many geotechnical applications, such as fill material in embankments, retaining walls and ash dyke raising. Pond ash is a mixture of unutilized fly ash and bottom ash transported to an ash disposal site with a large quantity of water. The deposition process of ash results in the settling of coarser bottom ash particles near the inflow point and finer fly ash particles away from the inflow point. This deposition process results in particle size variations throughout the same ash disposal site. Therefore, collecting pond ash from different locations of the same ash disposal site results in variations in its geotechnical properties. Thus, it is necessary to evaluate the liquefaction resistance and cyclic degradation response of pond ash with varying bottom ash content for using it to raise the ash dyke or as a fill material for any project in earthquake-prone areas. The present study is focused on the evaluation of liquefaction resistance (cyclic strength) and cyclic degradation response of pond ash with varying bottom ash content in its compacted state. A series of stress-controlled cyclic simple shear tests was performed on pond ash with the bottom ash content of 0 %, 20 %, 40 %, 50 %, 60 %, 70 %, 80 %, 90 % and 100 % at different dynamic loading conditions (cyclic stress ratio; CSR). This experimental research exhibited that the cyclic strength (cyclic resistance ratio; CRR) of pond ash increased with an increase in bottom ash content. It also reported that the cyclic degradation index of pond ash increased with an increase in the bottom ash content.