Agricultural Engineering Today

The control of seepage through either the body or the foundation or both of a hydraulic structure is of great significance from engineering point of view. In case of earthen and rock fill dams, this is achieved by providing core in the body and cut-off in the foundation of the dam. Sometimes, the foundation seepage is controlled by providing upstream blanket. This is controlled by using relatively impermeable materials for the core, cut-off and upstream blanket. Fly ash, though permeable, can be made relatively impermeable by adding cement to it. To achieve this goal an attempt was made to study the effect of cement on the permeability of fly ash. The material was collected from NALCO thermal power station, Anugul, Odisha. It was observed that the permeability of fly ash reduced with increase in cement percentage. The result of present investigation suggests that mixing of 15% of cement to the fly ash gives practically the same value of permeability which is found to be in the initial range of the permeability of clay. In order to check the strength of these mixtures for use in hydraulic structures, a comparison of compressive strength of cubes of fly ash mixed with cement at various percentages was made which showed that fly ash mixed with cement can be used safely in earthen embankments for effective seepage control.