Moisture effects and the mechanical response of granite beams

The load-displacement response (stiffness) of Charcoal granite beams is shown to increase by as much as 15% with drying of the rock. This behavior may be associated with the expansion of granite upon wetting. Because the modulus of Charcoal granite is about 20% larger in compression than in tension, it is claimed that the tensile prestrain due to moisture softens the response of the beams.