Characterization and classification of some local fly ashes

Abstract

Excavation of soil to use the top soil for road construction, earth dam construction, soil stabilization, backfill material, is a great matter of concern as it takes thousands of years to form the natural top soil. Due to soil excavation, deforestation occurs, which affects the bio-diversity. Industrial waste such as fly-ash, slag etc can be effectively used as alternate soil material. Utilization of fly ash is also a major challenge to the sustainability of thermal power stations and large scale utilization of fly ash in geotechnical constructions will reduce the problems of its disposal. As the properties of fly ashes vary from place to place; there is a need to check the variability of properties to for its effective utilization. Hence, before the utilization of fly ash as a construction material, it is necessary to study properties of fly ash from different sources, so that it can be used beneficially. In this present study, four fly ashes form local thermal power plants are considered. Several Geo engineering laboratory experiments were performed on these fly ashes to determine its properties. The experimental results of present fly ashes were compared with that available in the literature. The optimum lime content is found out in terms of unconfined compressive strength and is found to depend upon the source of fly ash. Using the classification scheme available in literature it was observed that all the four fly ashes considered here belong to the same class, but a wide variation in their properties is observed. Experimental results also showed strength, cohesion and friction are increased by stabilizing fly ash with lime. But the strength value and increase in stabilized value are also distinctly different for these four fly ashes. Hence, there is a need to consider an alternate classification scheme for fly ash for its effective utilization as a fill and embankment material.