Heat of hydration for fly ash as a predictive test
Coal combustion residues are commonly used in construction and for other engineering applications. These materials are complex and exhibit highly variable characteristics. Coal combustion fly ash, the most utilized of these materials, is commonly classified by its pozzolanic or cementitious properties. These properties are generally determined and monitored by empirical physical test procedures required for certification of these materials for use as a mineral admixture in cement. The current classification system does not provide a continuous scale rating for pozzolanic/cementitious behavior for these materials, or adequate information to assess the reactivity of these materials outside of their limited use in cement and concrete products. A test procedure, based on the heat of hydration, has been developed at the Energy and Environmental Research Center to more accurately assess the reactivity and behavior of these materials for utilization. The technique employs either a Dewar flask or a modified oxygen bomb calorimeter to determine the temperature change and rate of change after the addition of water to fly ash. X-ray diffraction is performed on the hydrated material following the hydration test to follow mineralogical changes as a result of the hydration process. A study of coal fly ash samples is underway to determine whether correlations exist between the temperature change and empirical test results. A protocol has been developed to assist in an improved classification scheme for coal fly ash.
- OSTI ID:
- 257018
- Report Number(s):
- CONF-950952--
- Country of Publication:
- United States
- Language:
- English
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