Early Hydration of Tricalcium Silicate |
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Authors: | M. E. TADROS JAN SKALNY R. S. KALYONCU |
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Affiliation: | Martin Marietta Laboratories, Baltimore, Maryland 21227 |
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Abstract: | The hydration of tricalcium silicate (C3S) in the preacceleration stages was studied. The C3S particles carry a positive charge during the early stages of hydration. Following a rapid hydrolysis of C3S, calcium ions adsorbed on the Si-rich surface of C3S particles, greatly reducing their further dissolution, thus initiating the induction period. The [Ca2+] and [OH-] continue to increase at lower rates and, because Ca(OH)2 crystal growth is inhibited by silicate ions, become supersaturated with respect to Ca(OH)2. When the supersaturation reaches a value of ∼1.5 to 2.0 times the saturation concentration, nuclei are formed, and rapid growth of Ca(OH)2 and C-S-H is initiated. These products act as sinks for the ions in solution, thus enhancing the further dissolution of C3S. |
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