Characteristics of fly ashes in India for use in cement and concrete

Fly ash is the most widely used supplementary cementitious material in the world. In India, although the widespread use of fly ash started only two decades ago, fly ash cement already makes up almost 70% of the market and still more fly ash is mixed in concrete. Yet, over a 100 Mt of fly ash produced in India every year is not utilised. This study presents a study of the characteristics of ten different fly ashes collected in India and the correlation between their chemical and physical properties. An understanding of the characteristics of the fly ashes is not only important to increase their consumption, but also to evaluate the potential of exporting fly ashes to other countries. It was found that, while most of the fly ashes had lower amorphous contents, they generally were finer than most cements. The results also indicate that the commonly used acid dissolution tests are not reliable to evaluate the reactivity of the fly ashes.