Effects of the Relative Humidity on the Crack Growth in Rocks

It is important to know the effect of the humidity on the fracturing in rock. However, none has reported the effect of only the relative humidity on the crack propagation under a constant temperature. In this study, the fracture toughness and subcritical crack growth in sandstone and granite were investigated in air. Especially, the effect of the relative humidity on the fracture toughness and the relation between the crack velocity and the stress intensity factor were investigated under a constant temperature. The fracture toughness decreased and the crack velocity remarkably increased in both rocks when the relative humidity was higher. The effect of the relative humidity was stronger than expected before. It is concluded that the change of the relative humidity in air has strong effects on the crack growth in rocks.