The paper considers the influence of fiberglass on the rheological and stress-strain properties of self-compacting concretes. The use of fiberglass in self-compacting concrete compositions makes it possible to achieve a sufficient coefficient of grain separation in coarse and fine fillers, which significantly influences the mobility and technological effectiveness of self-compacting mixes. Optimum compositions of self-compacting concretes are obtained, rational volumes of the hyper-plasticizing additive and of fiberglass are determined. The components were selected experimentally, in order to optimize the composition according to rheological characteristics. It is established that the use of fiberglass positively influences the stress-strain characteristics of concrete: it raises the compressive strength, as well as the bending tensile strength without deteriorating the workability and spreadabilityof the self-compacting concrete mix.