Characterization of Canadian fly ashes and their relative performance in concrete

Abstract

Eleven Canadian fly ashes were characterized and evaluated for their relative performance in concrete. Characterization included the determination of mineralogical composition, chemical composition, physical characteristics, and pozzolanic properties. The relative performance of each fly ash in concrete was evaluated through determination of the following properties of fresh and hardened concrete: slump, air content, bleeding, setting time, strength, modulus of elasticity, drying shrinkage, creep, and freezing-and-thawing resistance.The results indicate a wide range of chemical, physical, and pozzolanic properties for the fly ashes investigated. In spite of this, all the fly ashes studied are shown to be suitable for use in concrete. They affect, however, the properties of fresh and hardened concrete in different ways, and this should be taken into account when proportioning concrete containing these fly ashes. Key words: fly ash, concrete, pozzolanic activity index, bleeding, setting time, air-entrainment, strength, creep, shrinkage, freezing and thawing.