Investigation on geomechanical behaviour and microstructure of cement-stabilized fly ash

Abstract

Present laboratory study investigated the geomechanical behaviour of cement-stabilised fly ash. Class F fly ash collected from two different power plants in India was used in the study. Fly ash was stabilised with varying proportions of cement up to 10%, added in the ratio of dry weight of fly ash. Effects of addition of cement were evaluated on compacted fly ash–cement mix at optimum moisture content for rest period of 7, 14, 21 and 28 days. Results showed that the hydraulic conductivity of both the fly ash samples decreased by an order in magnitude when added with 10% cement. Effects of rest periods on hydraulic conductivity of cement-stabilised fly ash were found to be insignificant. Unconfined compressive strength of the cement-stabilised fly ash samples increased with increase in the cement content and rest periods, while the compression index of the stabilised samples decreased with increase in cement content. Different geomechanical behaviour was correlated with the microstructural changes in cement-stabilised fly ash, obtained through Field Emission Scanning Electron Microscope (FMSEM). Test results showed that cement stabilisation improved the engineering behaviour of both the fly ash, which may aid in their application as resource geomaterial.