Effect of temperature on the durability of class C fly ash belite cement in simulated radioactive liquid waste: synergy of chloride and sulphate ions.
نویسندگان
چکیده
The durability of class C fly ash belite cement (FABC-2-W) in simulated radioactive liquid waste (SRLW) rich in a mixed sodium chloride and sulphate solution is presented here. The effect of the temperature and potential synergic effect of chloride and sulfate ions are discussed. This study has been carried out according to the Koch-Steinegger test, at the temperature of 20 degrees C and 40 degrees C during a period of 180 days. The durability has been evaluated by the changes of the flexural strength of mortar, fabricated with this cement, immersed in a simulated radioactive liquid waste rich in sulfate (0.5M), chloride (0.5M) and sodium (1.5M) ions--catalogued like severely aggressive for the traditional Portland cement--and demineralised water, which was used as reference. The reaction mechanism of sulphate, chloride and sodium ions with the mortar was evaluated by scanning electron microscopy (SEM), porosity and pore-size distribution, and X-ray diffraction (XRD). The results showed that the chloride binding and formation of Friedel's salt was inhibited by the presence of sulphate. Sulphate ion reacts preferentially with the calcium aluminate hydrates forming non-expansive ettringite which precipitated inside the pores; the microstructure was refined and the mechanical properties enhanced. This process was faster and more marked at 40 degrees C.
منابع مشابه
Durability of class C fly ash belite cement in simulated sodium chloride radioactive liquid waste: influence of temperature.
This work is a continuation of a previous durability study of class C fly ash belite cement (FABC-2-W) in simulated radioactive liquid waste (SRLW) that is very rich in sulphate salts. The same experimental methodology was applied in the present case, but with a SRLW rich in sodium chloride. The study was carried out by testing the flexural strength of mortars immersed in simulated radioactive ...
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ورودعنوان ژورنال:
- Journal of hazardous materials
دوره 165 1-3 شماره
صفحات -
تاریخ انتشار 2009