The simulation results are used here to investigate the influences of the simultaneous rate processes on the
net rate of hydration (i.e., the overall rate as would be measured by
isothermal calorimetry or chemical shrinkage measurements).
We also examine howmathematical models based on boundary nucleation
and growth (BNG) [5,6] are influenced by solution composition.
These latter models arewidely used to fit the kinetics of hydration [7–9]
and typically assume that the growth rate of the transformed (product)
phase is constant. This assumption has important consequences for the
results of those models. Here, however, we extend the standard BNG
model for cement hydration to incorporate time-dependence of the
driving force for (and, therefore, rate of) C–S–H growth indicated by
HydratiCA. The generalized BNGmodel still provides good fits to hydration
rate data, albeit with different values of the fitting parameters; this
indicates that the usual assumption of constant nucleation and growth
rates is likely to result in erroneous values and interpretation of fitting
parameters.
Finally, both HydratiCA and the generalized BNG model are used to
draw conclusions about microstructure development in hydrating C3S
pastes, and to assess the relative likelihood of several hypotheses
proposed in the literature to explain (1) the origin of the period of
slow reaction shortly after mixing C3S with water, (2) the observed
peak in hydration rate that separates the acceleration period from the
deceleration period and (3) the insensitivity of hydration kinetics to
water/cement mass ratio (w/c).
The simulation results are used here to investigate the influences of the simultaneous rate processes on thenet rate of hydration (i.e., the overall rate as would be measured byisothermal calorimetry or chemical shrinkage measurements).We also examine howmathematical models based on boundary nucleationand growth (BNG) [5,6] are influenced by solution composition.These latter models arewidely used to fit the kinetics of hydration [7–9]and typically assume that the growth rate of the transformed (product)phase is constant. This assumption has important consequences for theresults of those models. Here, however, we extend the standard BNGmodel for cement hydration to incorporate time-dependence of thedriving force for (and, therefore, rate of) C–S–H growth indicated byHydratiCA. The generalized BNGmodel still provides good fits to hydrationrate data, albeit with different values of the fitting parameters; thisindicates that the usual assumption of constant nucleation and growthrates is likely to result in erroneous values and interpretation of fittingparameters.Finally, both HydratiCA and the generalized BNG model are used todraw conclusions about microstructure development in hydrating C3Spastes, and to assess the relative likelihood of several hypothesesproposed in the literature to explain (1) the origin of the period ofslow reaction shortly after mixing C3S with water, (2) the observedช่วงราคาไล่น้ำที่แยกระยะเร่งความเร็วจากการรอบระยะเวลาของการชะลอตัวลงและ (3) insensitivity ของจลนพลศาสตร์ไล่น้ำให้น้ำ/ซีเมนต์อัตราส่วนมวล (w/c)
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