Influence of Water-to-Cement Ratio on Hydration Kinetics: Simple Models Based on Spatial Considerations.
Influence of Water-to-Cement Ratio on Hydration
Kinetics: Simple Models Based on Spatial
Bentz, D. P.
Cement and Concrete Research, Vol. 36, No. 2, 238-244,
cements; kinetics; hydration; water; experiments
Based on simple spatial considerations, models to
describe the hydration kinetics of portland cement are
developed and compared to existing experimental data,
particularly in terms of the influence of the starting
water-to-cement ratio (w/c) on hydration rates. The
conceptual basis for the models is to relate the
instantaneous hydration rate to local probabilities for
the dissolution and precipitation of the cement phases.
In the simplest model, hydration kinetics are strictly a
function of the volume fraction of local (global)
water-filled porosity, as computed based on Power's
model for cement hydration. While this simplest model is
inadequate to quantitatively describe the observed
hydration behavior in real cement pastes with various
w/c, a more complicated version of the model that
considers both the water-filled porosity and the
unhydrated cement volume fractions appears to provide an
adequate description. Finally, the models are extended
to consider the influence of the replacement of a
portion of the cement by an inert filler on the
resulting hydration kinetics.