Angle of internal friction for pond ashes

Abstract

Thermal power stations use pulverized coal as fuel, producing enormous quantities of ash as a waste product of combustion. Nearly 800 million metric tons of ash is produced each year all over the world. In India, presently 97 million metric tons of ash is produced annually by power stations. The problem of ash disposal is a difficult one due to the limited availability of vacant space around the power plants. In view of the large quantities of ash, its bulk utilization is essential, which is possible only through geotechnical applications such as embankments, back-fill material, subbase material, and the like. For the above applications, one of the important engineering properties is the angle of internal friction, which is determined either by box shear or triaxial shear tests. This paper examines the angle of repose of pond ashes and its relation with the angle of internal friction, using direct shear tests. Determination of the angle of repose is an easy and quick procedure for cohesionless materials. The angles of repose of sand and of quarry dust also are examined for comparison purposes. A relationship between angle of internal friction for materials in the loose, dry condition and the angle of repose is established. Further, a simpler method of measurement of the angle of repose is proposed.