Hydration hardening mechanical stresses

Mechanical stresses are necessary for the crystallization contacts to be established in hydration structures in the course of hydration hardening. These stresses are either applied externally or originate from the directional growth of the crystals inside the already formed network. Mechanical stresses may also be caused by the weight of powders or result from the action of capillary forces acting in the drying menisci. 

Another possible way to substantially modify the nature of contacts is to use hydration hardening of the magnesium oxide followed by dehydration instead of mechanical pellet pressing (Figure 7.63e) [120,149,160]. This allowed one to establish stronger phase contacts while simultaneously removing the residual internal stresses. 

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