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The Influence of Slate Waste Activation Conditions on Mineralogical Changes and Pozzolanic Behavior
Author(s) -
Frías Moisés,
Vigil de la Villa Raquel,
García Rosario,
Sánchez de Rojas M. Isabel,
Juan Valdés Andrés
Publication year - 2013
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12387
Subject(s) - pozzolan , pozzolanic reaction , pozzolanic activity , chlorite , chemistry , calcium silicate hydrate , chemical engineering , mineralogy , clay minerals , cement , metallurgy , materials science , portland cement , engineering , quartz
The transformation process of clay minerals into pozzolanic products for use as active additives in cement matrixes has been closely studied by both the scientific community and the cement industry. Sourcing these additions from recycled waste products is widely prioritized in environmental policies, because of their associated environmental benefits. This article reports an exhaustive analysis of slate waste in Spain, for its eventual use as an alternative source of pozzolans, based on activated phyllosilicates. The analysis examines the effect of activation conditions on mineralogy and the formation and evolution of the hydrated phases that form during the pozzolanic reaction at 28 days. The results show good pozzolanic activity in the starting slate wastes activated between 800°C and 1100°C of temperature for 2 h of retention, on which basis 1000°C and 2 h were recommended as the more suitable activation conditions for these activated slate wastes ( ASW ), as total destruction of all phyllosilicates is ensured under those conditions. The hydrated phases formed during the pozzolanic reaction in the ASW / Ca (\ OH ) 2 system were calcium silicate hydrate gels (CSH), randomly interstratified chlorite ( Cl ) /smectite with variables containing chlorite/smectite ratios 30% chlorite, 40% chlorite, 50% chlorite, 60% chlorite, respectively, and monosulfoaluminate ( C 3 A · SO 4 Ca ·12 H 2 O ) directly related to the activation process used in this article. All of these findings support the viability of slate waste for use as a pozzolanic addition.