Influence of SO₄² on volumetric deformation of cement motar under environment of invariable temperature and variational humidity

In the multi-purpose environment simulation system, cement mortars that had dipped in Na₂SO₄ solution of different concentration carry on mass losing, volumetric deformation tests and SEM analysis under invariable temperature and variational humidity. The result indicated that under invariable temperature and variational humidity, its mass losing and linear shrinkage increased along with the relative humidity reducing, but the growth speed obviously of humidity (↙50%)→(↗50%) section slowed down; and its mass losing rate reduced along with the increasing concentration of Na₂SO₄ solution, but linear shrinkage then otherwise; after dryness-wet circulation ended, the mass losing and the linear shrinkage of mortars were lower than the starting value, also the intervention of salted solute increased the starting to end interpolation.