Modeling Ion and Fluid Transport in Unsaturated Cement Systems in Isothermal Conditions.
Modeling Ion and Fluid Transport in Unsaturated Cement
Systems in Isothermal Conditions.
Samson, E.; Marchand, J.; Snyder, K. A.; Beaudoin, J. J.
Cement and Concrete Research, Vol. 45, No. 1, 141-153,
cements; diffusion; transport properties; degradation;
A description of ionic transport in unsaturated porous
materials due to gradients in the electro-chemical
potential and the moisture content is developed by
averaging the relevant microscopic transport equations
over a representative volume element. The complete set
of equations consists of time-dependent equations for
both the concentration of ionic species within the pore
solution and the moisture content within the pore space.
The electrostatic interactions are assumed to occur
instantaneously, and the resulting electrical potential
satisfies Poisson's equation. Using the homogenization
technique, moisture transport due to both the liquid and
vapor phases is shown to obey Richards' equation, and a
precise definition of the moisture content is found. The
final transport equations contain transport coefficients
that can be unambiguously related to experimental
quantities. The approach has the advantage of making the
distinction between microscopic and bulk quantities