The impacts of raw, apatite-synthesized and organic-treated coal fly ash amendment on soil/sand water retention capacity

Abstract

Coal fly ash (FA) utilization to increase soil moisture retention was motivated to solve soil productivity reduction via desertification and FA recycle problem in arid and semi-arid areas. This study investigated the effect of raw and treated FA amendment on water retention capacity (WRC) of soils (decomposed granite soil and akatama soil) and sands (silica sand and river sand) at room temperature and 40°C. The effects of treated FA amendment has complicated dependency on treatment methods, soil/sand type and temperature. This study found that water repellency, surface area, particle size distribution of FA, capillary water content and pF were insufficient to explain FA amendment effect. However, multi regression analysis suggests that relative changes of WRC after FA amendment can be statistically explained by variations of specific surface area and water repellency with unknown constant. Organics-added thermal treatment suggests appropriate modification of FA surface properties at once is effective to change WRC.