Prediction of cement paste pore water pressure variations during setting period

Results from tests,using 1–10 m formworks, conducted to examine the evolution of pore water pressure in a fresh cement paste during setting are presented. Experiments reveal that, from the initial state up to cancellation, profiles of both pore water pressure and total lateral pressure are hydrostatic. Simultaneously, the evolution kinetics of both pressures are identical. Consequently, the variation of the lateral pressure envelope during setting is modelled using the Richards equation. Modelling requires the identification of two parameters (permeability of the fresh cement paste and a source term) that describe water requirements during setting. The permeability coefficient is examined through a drainage experiment, coupled to the inverse analysis for identification of the coefficients resulting from the solution of the Richard's equation. Using the parameters identified, the results of the numerical simulation of the pressure variations into the formwork, are in good agreement with the experiment.