  We study the kinetics of absorption of water in portland cement mortars added
with 60, 70 and 80% of granulated blast furnace slag (GGBS or Slag) cured in
water and at open air and preheating at 50 and 100 C.A mathematical model is
presented that allows describing the process not only in early ages where the
capillary sorption is predominant but also for later and long times where the
diffusive processes through the finer and gel pores are considered. The fitting
of the model by computerized methods enables us to determine the parameters
that characterize the process: i. e. the sorptivity coefficient (S) and
diffusion coefficient (D). This allows the description of the process for all
times and offers the possibility to know the contributions of both, the
diffusive and capillary processes. The results show the influence of the curing
regime and the preheating temperature on the behavior of GGBS mortars.
