The paper presents an analysis of the dispersed reinforcement effect by polypropylene fiber on the claydite-concrete cube strength. The investigation objective is to determine the reinforcement ratio of claydite-concrete by polypropylene fiber. As a result of investigations, special attention must be paid to the correct preparation technology at the time of a concrete mixture preparing. Otherwise, the polymer fiber introduction will have a negative effect. In this case, the coarse aggregate use is a significant condition. The particle size influence of expanded clay gravel on the elastic modulus of claydite-concrete was also shown. It is recommended to use expanded clay gravel with smaller fractions in accordance with investigations. The maximum and minimum allowable content of polypropylene fiber was determined. The cube strength increase of claydite-concrete by polypropylene fiber is achieved by this allowable content in comparison with unreinforced claydite-concrete with a similar concrete mixture. The most effective reinforcement ratio was empirically determined, and the maximum strength increase was also recorded. The polypropylene fiber should be added in a percentage ratio depending on the cement mass with constant cement content in accordance with investigations. The fiber introduction instead of cement mass negatively affects on the strength characteristics. In general form, the prospects for further investigations are described.