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On-line version ISSN 1678-4553
OLIVEIRA, I. R.; GARCIA, J. R. and PANDOLFELLI, V. C.. Influence of dispersant and accelerator additives on hydration of calcium aluminate cement and cement-matrix. Cerâmica [online]. 2006, vol.52, n.323, pp. 184-193. ISSN 1678-4553. http://dx.doi.org/10.1590/S0366-69132006000300012.
A growing demand for refractory castables with specific behaviors has been promoting a continuous technological evolution, in which, one of the most important aspects concerns in a deep knowledge of hydraulic binders. These materials present a great influence on the rheological properties and mechanical strength development of castables, defining their workability periods and demoulding times, respectively. The hydration process of calcium aluminate cement is influenced by the presence of additives, which affects the setting and demoulding time of the shaped body. Besides that, the alumina addition to cement also influences the hydration behaviour, as well as, the length of the induction period, the composition of the phases and of the hydration products. Therefore, in this work it was studied the influence of the dispersant and/or accelerator additives on the hydration process of calcium aluminate cement and cement-matrix. Independent of the system, the dispersant additives acted as retarders on hydration process, mainly the citric acid and diammonium citrate. These additives were the most efficient to combine with the accelerator (Li2CO3) resulting an intermediate setting time, good workability and a short demolding time.
Keywords : hydration; calcium aluminate cement; dispersants; matrix; accelerator.