Deformation parameters of high-strength steel fiber concrete under long-term load application

Abstract

This article contain an experimental study of the rheological characteristics of high-strength steel fiber concrete (SFRC) that is used for the manufacture of permanent formwork. Permanent SFRC formwork is used in the construction of reinforced concrete structures of new generation nuclear power plants (NPP), where due to improved physical and mechanical characteristics it is used as a load bearing element. As a result, a structure with combined reinforcement is obtained, requiring improvement of existing calculation methods, including continuously acting load. The use of existing models of concrete behavior under conditions of continuous loading using SFRC is limited and requires experimental refinement. Studies in the field of nonlinear creep, where, according to a number of studies, the use of steel fibers is most effective are of a particular interest. The high labor intensity and duration of creep tests limited the research to two compositions of SFRC recommended for the manufacture of formwork and fine-grained matrix. Based on the established rheological characteristics at loading levels 0.3, 0.8, 0.85 and 0.9, analytical dependences that allow predicting the values of creep strain at different loading levels are obtained. The presented dependences are recommended for the calculation of reinforced concrete structures with non-removable formwork made of SFRC under a long-term load.