Abstract

Based on the experimental and theoretical studies from the standpoint of the adsorption theory of creep, the authors show the peculiarities of the concrete behavior in time and propose a universal graph of the limit characteristics of concrete, including: the limits of strength, elastic deformation, linear creep, endurance. It is established that the limit strength value R changes in time and depends on the velocity of load application, while the elastic deformation limit is a constant value and does not depend on the age of concrete and the load application velocity. The maximal limit deformation of concrete of any composition is a constant value under repeated loads as well as under the constant load. The breaking of concrete in time occurs due to the combined action of external forces, which is expressed in terms of the trapezoid area, and due to an additional effect of the wedging action of water which is equal to the triangle area. According to the theory on the nature of concrete creep, the cause of the creep in the region of elastic deformation is the influence of water adsorption, which shows itself in its wedging action on the reversible micro cracks of concrete, i.e. the creep in the elastic deformation region is completely reversible, and the wedging action of water can be regarded as an additional stress to the stress due to load.