Swelling strains from density measurements

Water in contact with silica glass surfaces diffuses into the glass, and reacts
with the silica network under hydroxyl generation. Clear evidence has been
reported in the literature for a volume swelling due to the water uptake and
reaction in silica. In the past, the authors showed in a couple of papers the
principle effects of volume swelling by hydroxyl generation on mechanics
and fracture mechanics properties.
From literature data on density as a function of water content a linear
dependence of the volume swelling strain with water concentration was
established. This dependency will be discussed in the present report
including data scatter.