Study on the Characterization and Classification of Fly Ash Samples Obtained Locally

Abstract

The excavation of soil for various construction purposes, such as road construction, earth dam construction, soil stabilization, and backfill material, raises significant concerns as it takes thousands of years for natural topsoil to form. This excavation often leads to deforestation, which negatively impacts biodiversity. To address these issues, industrial waste materials like fly ash and slag can be effectively utilized as alternatives to natural soil. The sustainable utilization of fly ash is particularly important for thermal power stations, as large-scale usage in geotechnical construction projects can reduce the challenges associated with its disposal.

However, since the properties of fly ash can vary depending on its source, it is crucial to assess the variability of these properties before using fly ash as a construction material. In this study, four different fly ashes from local thermal power plants were examined through various geotechnical laboratory experiments to determine their properties. The results obtained from these experiments were then compared with existing literature on fly ash properties.

The study identified the optimum lime content required for achieving a desirable unconfined compressive strength, which was found to depend on the specific source of fly ash. Using an existing classification scheme for fly ash, it was observed that all four fly ashes belonged to the same class. However, significant variations in their properties were noted. The experimental results also indicated that the strength, cohesion, and friction of fly ash could be improved by stabilizing it with lime. Nevertheless, the strength values and the degree of improvement differed noticeably among the four fly ashes. Therefore, it is necessary to consider an alternative classification scheme for fly ash when utilizing it as a fill and embankment material in order to ensure its effective utilization.