HEAT OF HYDRATION OF FLY-ASH AS A PREDICTIVE TOOL

A test procedure based on heat of hydration was developed to assess mo re accurately the reactivity and behaviour of fly ash for utilization. The technique uses a Dewar flask or a modified oxygen bomb calorimete r to determine the temperature change and rate of change after the add ition of water to fly ash. X-ray diffraction is performed on the hydra ted material after the hydration test to follow mineralogical changes due to the hydration process. A study of coal ash samples is under way to determine whether correlations exist between the temperature chang e and results from empirical tests, such as those of the ASTM, used to determine properties of ash for engineering applications. A protocol has been developed for an improved classification scheme for coal ash.