13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- specific zones. 1- This zone corresponds to the loading of the wet sample with a displacement speed of 0,5mm/min. The overall stiffness is equal to 260N/mm. According to a finale displacement of 1mm, the corresponding force is 355N. 2- During ten minutes, the force is kept constant. The sample mechanical state is in a creep configuration. We can observe the displacement evolution versus time. At this state, the relative humidity is maintained at 85%. 3- At this time, the phase of drying starts. According to diffusion process, the specimen begins to dry from the outside surface. The creep response results on the combination of mechano-sorptive and shrinkage effects. We can observe a displacement blocking characterizing of mechano-sorptive effects and, more particularly, its hygro-lock properties [3], [4], [5]. 4- The last phenomenon is characterized by a continuum increase of displacements. According to a non linear behavior, this phase can be assimilated at a secondary creep state accentuated by the 3D diffusion process. The total collapse can be observed after a total time of 2h40. he th Figure 10. Experimental results 5. Conclusion and outlook This present thermodynamic approach allows studding the crack growth process by taking into account the global dissipation process induced by the new crack surfaces formations and a process zone development. The generalization of this approach for climatic variations request introducing mechano-sorptive behavior in the energetic balance. In the same time, the global behavior needs the uncoupling of shrinkage-swelling effect. In this last case, a finite element modeling allows the prediction of the free displacement induced by moisture content level taking into account orthotropic properties in the specimen thickness and diffusion process in the transverse section.
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