Hydroxyl concentrations on crack surfaces from measurements by Tomozawa, Han and Lanford

The effect of stress-enhanced hydroxyl concentration in silica penetrated by water could be proved by using hydrogen measurements from literature (Tomozawa, Han and Lanford 1991). The concentration of water penetrated into silica during a subcritical crack growth test is strongly larger than the water diffused into unstressed silica surfaces. From this result it could be concluded that the equilibrium constant of the water-silica reaction is strongly enhanced due to the near-tip tensile stresses of cracks and that the reaction volume change is positive.