Geotechnical characterization of some Indian fly ashes

This paper reports the findings of experimental studies with regard to some common engineering properties (e.g., grain size, specific gravity, compaction characteristics, and unconfined compression strength) of both low and high calcium fly ashes, to evaluate their suitability as embankment materials and reclamation fills. In addition, morphology, chemistry, and mineralogy of fly ashes are studied using scanning electron microscope, electron dispersive x-ray analyzer, x-ray diffractometer, and infrared absorption spectroscopy. In high calcium fly ash, mineralogical and chemical differences are observed for particles, >75 mu m and the particles of <45 mu m size. The mode and duration of curing significantly affect the strength and stress-strain behavior of fly ashes. The geotechnical properties of fly ash are governed by factors like lime content (CaO), iron content (Fe2O3) and loss on ignition. The distinct difference between self-hardening and pozzolanic reactivity has been emphasized.