High-strength steel fiber concrete, made on the basis of fine-grained high-strength concrete, is a quite promising building material, in particular, for the construction of high-rise buildings and structures of increased massiveness. The introduction of steel fiber into the concrete matrix can significantly reduce the influence of such shortcomings of fine-grained concrete as increased fragility and explosive nature of fracture, and also positively affects the tensile properties of concrete. However, the widespread use of high-strength steel fiber concrete is currently limited, among other things, by the lack of an experimentally relied normative framework for this material. The proposed article aims to bridge this gap. Modern engineering trends are aimed at introducing into practice diagram methods of calculation based on real diagrams of material deformation under load. This article describes the technique of constructing isochron diagrams for fine-grained high-strength concrete and steel fiber concrete with disperse reinforcement in the amount of 1.5% by weight, made from Russian-made components. Isochron diagrams allow you to calculate the deformation of the material depending on the level of load at any time, including during prolonged loading. There have been made changes to the existing methodology, allowing to take into account the nonlinearity of both current and ultimate creep characteristics depending on the level of loading. The proposed theoretical dependences give good convergence with the experimental data.