Critical Evaluation of the Drying Water Retention Characteristics of a Class F Indian Fly Ash

The utility of waste fly ash, especially class F, in agriculture, geotechnical, and geoenvironmental applications have increased manifold. In most of these cases, precise determination of water retention characteristics (WRCs) of fly ash is mandatory. The WRC is generally expressed in terms of graphical relationship between water content and suction. There are not many studies that deal with the critical evaluation of fly ash WRC and its uniqueness. With this in mind, experiments were conducted on a Class F Indian fly ash using different measurement procedures. A tensiometer has been used for measuring matric suction in fly ash. This is primarily because of the fact that a cohesionless material like fly ash with its silt dominated particle size will not exhibit a very high range of suction. The results obtained in this study clearly indicate that the near saturation and desaturation portion of WRC could be determined using tensiometer measurements. On the basis of the results, the parameters of commonly used WRC equations have been reported for the fly ash. Analysis has been done to understand the influence of compaction conditions on fly ash WRC. It has been demonstrated that the WRC of fly ash established by using different procedures may not be unique, and initial compaction state influences the fly ash WRC.