Determination of Moisture Diffusivity during Drying of Mortar Cement: Experimental and Modeling Study

The aim of this study is the experimental characterization of the behaviour of a mortar during convective drying. We focalise on mortar that has a rate water-cement of 0.5. The drying tests are developed in a micro-convective dryer that can use samples weighing from 0 to 8g. The advantage of these experiments is to reproduce the natural conditions that can be found during the treatment of the mortar-atmosphere problems. The response of the drying curve or the drying kinetic depends on the applied drying conditions. So, the temperature of the air varies from 60℃ to 130℃, the velocity of the air is changed from 2 m.s-1 to 5 m. s-1 and the relative humidity is kept less than 1.7%. The comparison between the experimental results and the proposed analytical solutions of the equation of diffusion represented by Fick’s law, applied for a finite shape, allows determination of the values of the diffusion coefficient. It has a value of 1.71×10-10 m2.s-1 at 60℃, 13.69×10-10 m2.s-1 at 90℃ and 16.27×10-10 m2.s-1 at 130℃. Calculation of the activation energy and the D0 constant are also possible.