Structural polypropylene and steel fibers were included in the alkali-activated mix at 1.5% and 5% of the total binder weight, respectively. Breaking strength increased significantly by 19.28% and 26.80% due to the inclusion of structural polypropylene and steel fibers, respectively. The study of the influence of the morphology of the coarse aggregate on the properties of self-compacting high-performance fiber-reinforced concrete (SCHPFRC) was carried out in [9]. The results obtained showed that the morphology of the coarse aggregate grains significantly affects the strength, deformation, and rheological properties of SCHPFRC. In [10], an experimental analysis of the bending behavior of reinforced concrete beams reinforced with fibrous polymer materials using surface mounting and external bonding methods is presented. Six double-span beams with a total length of 3200 mm and a 120/200 mm cross-section were tested under short-term and monotonically increasing loads. The authors obtained the results of an increase in the maximum carrying capacity of reinforced beams by 22-82% compared to an unreinforced control beam. A significant result is information that the ductility of the beams reinforced with CFRP rods was satisfactory, while the ductility of the beams reinforced with CFRP rods was very low; therefore, the nature of the destruction of these beams was fragile. The assortment of fibers used is very extensive, and, according to the accepted classification, they are divided:  
* By the modulus of elasticity of the fiber--into high-modulus (steel, carbon, glass, etc.) and low-modulus (polyppropylene, viscose, etc. );
* By origin--into natural (asbestos, basalt, wool, etc.) and artificial (viscose, polyamide, etc. );For the main material--into metal (most often steel) and non-metal (synthetic, mineral). In dispersed reinforcement, concrete hardening with fiber is based on the hypothesis that the composite matrix transfers the applied load to the fibers uniformly distributed in it due to the tangential forces that act on the interface. If the fiber elastic modulus exceeds the modulus of elasticity of the concrete matrix, the main part of the stresses is absorbed by the fibers, and the total strength of the composite is directly proportional to the fiber volume fraction. It is known that the main feature of composites, including fiber-reinforced concretes, is the heterogeneity, which determines the complexity of the structure of such materials [11; 12]. Fiber-reinforced concrete is a structure-in-structure type material with a very complex poly-structural organization, in which at least two scale levels can be distinguished:  
* Microscopic (the level of cement stone), which establishes the phase composition of the neoplasms, the type, nature of porosity, etc. * Macroscopic (concrete level), which establishes the type and properties of aggregate, cement stone, fiber and the ratio between them, and the uniformity of distribution of these components in the volume of fiber-reinforced concrete. The structural-technological model of fiber-reinforced concrete was proposed in [13], a component of which is a macrostructural cell, the dimensions of which depend on the degree of saturation with the reinforcing fiber and are commensurate with the geometric characteristics of the fibers and the dimensions of the filler. All components that make the macrostructural cell are interconnected by contacts, the strength of which determines the basic properties of dispersion-reinforced concrete. Depending on the place of formation, contacts can be divided into three types: between cement grains; between cement stone and aggregate; between fine-grained concrete and fiber. Cement stone, aggregate and fiber do not occupy the entire volume, since various pores remain, which may contain capillary and free water, as well as air [14; 15; 16].