A Study of Alteration Phases on Glass-bonded Zeolite and Sodalite using the Vapor Hydration Test


This paper focuses on the reaction of glass-bonded zeolite and sodalite ceramic waste forms, naturally occurring sodalite, and their respective alteration phases that formed after reaction in a Vapor Hydration Test (VHT). Scanning electron microscope (SEM) analysis of the glass-bonded zeolite and sodalite samples indicate that NaCl is the major alteration phase present, along with KC1, Na-Al-Si, and Na-K-Ca-Al-Si phases. The order of precipitation of salt crystals from ceramic waste form occurred in the sequence NaCl => KC1 => CaCb and MgCb. We also found aluminum silicate phases containing Ca, Mg, K-Na-Ca, K-Mg, Na-K-Mg, K-CaNa-Mg, as well as CaCOj, SiC"2. The ratio of Si/Al in the alteration phases was noted to increase from approximately 1.5 to 5 during the progressive alteration of the samples. This trend indicates a relative increase in the contribution of silicon from the relatively Si-rich glass regions of the samples over time. Phases enriched in Cs, Ba and rare earth elements (RE) were also observed on the altered samples. Alteration phases initially appeared along the micro-fractures during the early stages of alteration. The number of micro-fractures, density of alteration phase cover, and grain size of alteration phases increased with reaction time and temperature. © 1959 Materials Research Society.


Geosciences and Geological and Petroleum Engineering

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Publication Date

01 Dec 1999

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