Liquid limit determination of class F coal ash

Abstract

Large production of coal ash, a waste material, demands its bulk utilization. Bulk utilization of these ashes is possible only through geotechnical applications such as embankment construction, as a back-fill material, a subbase material, and the like. Hence their physical and engineering properties need to be determined for effective utilization. Liquid limit is one of the important physical properties. The existing popular methods of liquid limit de termination of soils, namely Casagrande's percussion method and the falling cone method, have limitations for their use in nonplastic materials like coal ash. In this paper, a new method has been proposed to determine the liquid limit of coal ash. The proposed method is based on the premise that at its liquid limit water content, soil/coal ash does not imbibe or give out any water under a particular vertical stress under the Ko condition. This vertical stress is found to be 0.9 kPa. Experimental results are presented to substantiate the proposed method.