Mineralogy and microstructure of hydrated phases during the pozzolanic reaction in the sanitary ware waste/Ca(OH)2 system

摘要

Despite technological improvements in its production process,udthe sanitary ware industry inevitably generates a certain volumeudof discards, products whose quality is not up to standard.udThe present paper is the first to scientifically explore claybasedudsanitary ware waste (SW) with a view to its valorizationudas an addition in the design of new, more environmentallyudfriendly cements. The focus is on characterization of the wasteudand its pozzolanicity, as well as the structural and microstructuraludchanges taking place in the pozzolan/Ca(OH)2 system inudthe first 90 d of reaction. The findings show that pozzolanicityudin clay-based waste is comparable to the activity observed inudsilica fume (SF) and higher than that found in other clay-basedudmaterials and fly ash (FA). The microstructural study of theudclay-based waste/Ca(OH)2 system, in turn, reveals that theudproportion of C–S–H gels rises with hydration time. These gelsudare characterized by long mean chain lengths (MCL) and lowudCa/Si ratios. The intrinsic characteristics of this thermallyudactivated clay-based waste qualify it as a type Q pozzolans asuddefined in the European cement standards, making it apt foruduse in the manufacture of CEM II, IV, and V cements.