Effect of Curing Temperature and Free Lime Content in Fly Ash on Basic Properties and Autoclave Expansion of Fly Ash Mixtures

Abstract

This study incorporates a detailed experimental program executed to determine the degree up to which the autoclave expansion of fly ash mixtures is sensitive to curing temperature. Three types of fly ashes were used and free lime was applied to increase the free lime contents in different fly ashes up to 10%. The influence of curing temperature on autoclave expansion of the mixtures was evaluated by curing under two temperatures, i.e., 23°C and 29°C for 24 hours after mixing. Experimental results exhibited that a higher free lime percentage resulted in a higher magnitude of autoclave expansion. It was observed that at a curing temperature of 23°C, the autoclave expansion was higher than the expansion of samples cured at a temperature of 29°C. Most of the mixtures, except the mixtures containing 40% fly ashes with the free lime amount of 10% and cured at a lower curing temperature, showed autoclave expansion values below the allowable limit recommended by ASTM C618.