Experimental and theoretical investigation of slow reversible deformation of concrete in surface-active media and physical model of processes

Many-year investigations of the nature of damping creep of rigid bodies and materials led to the discovery of the fundamental character of this phenomenon. It occurs only when a rigid body comes in contact with a surface-active medium (liquid or gaseous), which brings about a decrease of free surface energy of a rigid body as a result of adsorption, chemosorption or wetting. The reversibility of the process consists in a gradual disappearance of creep deformation when the action of the surface-active medium stops. To clarify the essence of processes, physical model is constructed by using Griffith's scheme and the well-known representation formulas of deformation origination and failure processes. The total creep deformation is caused by the formation and opening of microcracks throughout the material volume under the action of load. This supposedly happens in macroscopically homogeneous silicate and organic glasses, while in polycrystals (tuff, gypsum, steel) contacting with a surface-active medium the microcracks are formed mainly on the grain boundaries. (author)