The following points can be highlighted from this comparison of hydration and capillary porosity percolation as measured experimentally and predicted by CEMHYD3D:
Figure 16. Comparison of LTC-estimated and CEMHYD3D predicted percolated capillary porosity volume fractions vs. time for w/c = 0.45 cement paste hydrated under saturated conditions at 40 ºC.
Figure 17. ltc-estimated percolated (damaged) capillary porosity volume fractions vs. time for various cement pastes cured under sealed conditions.
1) in agreement with previous results,5 loss-on-ignition measurements were found in this study to be a reliable indication of degree of hydration for w/c ≥ 0.35 cement pastes. However, for w/c = 0.25 cement pastes and particularly for 40 ºC curing, the non-evaporable water content per unit hydration appears to increase with time.19, 20 Under higher temperature curing conditions, LOI-interpreted degrees of hydration should not be used for cement pastes with w/c ≤ 0.25.
2) Sealed curing can result in a repercolation of the capillary porosity that was initially depercolated by hydration, due to chemical shrinkage and its accompanying self-desiccation inducing autogenous stresses and strains on the cementitious gel-like hydrated microstructure.
3) While an increase in curing temperature from 20 ºC to 40 ºC significantly accelerates cement hydration, it also produces a coarser capillary porosity system that takes longer to achieve complete depercolation in w/c = 0.35 cement pastes (both in terms of required time and degree of hydration).
4) In general, reasonable agreement was observed between the experimental measurements and CEMHYD3D predictions both for achieved degrees of hydration and for the volume fractions of connected capillary porosity.
5) The volume fraction of connected capillary porosity created by autogenous damage under sealed curing could be effectively estimated, using the LTC measured peak height at −15 ºC, as was first "validated" for saturated curing conditions by comparison to the volumetric predictions of the CEMHYD3D model. Based on the limited experimental data obtained to date, the damage appears to increase with either a decrease in w/c or an increase in curing temperature.