Dimensional Analysis of Ionic Transport Problems in Hydrated Cement Systems. Part 1. Theoretical Considerations.
Dimensional Analysis of Ionic Transport Problems in
Hydrated Cement Systems. Part 1. Theoretical
Barbarulo, R.; Marchand, J.; Snyder, K. A.; Prene, S.
Cement and Concrete Research, Vol. 30, No. 12,
1955-1960, December 2000.
cements; dimensional analysis; transport properties;
ionic transport; leaching; reaction
The validity of the local equilibrium assumption in
hydrated cement systems, that a particular chemical
reaction is instantaneous with respect to transport, is
examined using a dimensional analysis of electrochemical
transport in cementitious materials. The transport
equation parameters are scaled, resulting in a
dimensionless equation. The dimensionless coefficient
for each reaction/transport term determines its relative
contribution to the overall process. The diffusion of
ions in a reacting porous medium can be fully described
on the basis of six independent dimensionless numbers.
The analysis demonstrates that the kinetics of the
reaction determines the appropriate time constant for
the analysis. The formalism is applied to the
dissolution of calcium hydroxide under an
electrochemical potential gradient. The results are in
agreement with previous observations and demonstrate
quantitatively the local equilibrium hypothesis is valid
in most practical cases where ions are transported by
diffusion through a saturated material.