Although empirical expressions have been suggested for
Qh [15], time-dependent nonlinear finite element solution
of the governing equation given by Eq. (18) allows one
to utilize the basic principles of chemistry to determine
these values at each time increment of the iterative solution
as long as the amount of CO2 transported into the
concrete and the amount of Ca(OH)2 in the hydrated
cement paste are known. The calculated Qh value can be
modeled as a source term in the finite element formulation
and Eq. (25) can be solved by using a non-linear
solution scheme.