Abstract
We reconsider a number of measurements for the overall hydration kinetics of tricalcium silicate pastes having an initial water to cement weight ratio close to 0.5. We find that the time dependent ratio of hydrated and unhydrated silica mole numbers can be well characterized by two power laws in time, x/(1-x) approximately (t/t(x))(psi). For early times t<t(x) we find an "accelerated" hydration (psi=5/2) and for later times t>t(x) a parabolic behavior (psi=1/2). The crossover time is estimated as t(x) approximately 16 h. We interpret these results in terms of a global second-order rate equation indicating that (a) hydrates catalyze the hydration process for t<t(x), (b) they inhibit further hydration for t>t(x), and (c) the value of the associated rate constant is of magnitude 6 x 10(-7) - 7 x 10(-6) l mol(-1) s(-1). We argue, by considering that the hydration process actually occurs via diffusion limited precipitation, that the exponents psi=5/2 and psi=1/2 directly indicate a preferentially plate-like hydrate microstructure. This is essentially in agreement with experimental observations of cellular hydrate microstructures for this class of materials.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Physical review. E, Statistical, nonlinear, and soft matter physics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
