The article presents the results of a study of a modifying additive based on activated rubber crumb. Its effect on the rheological properties of bitumen binder was studied at concentrations of 4%, 7%, and 10% of the bitumen mass. It was established that the optimal content of the additive, which ensures the optimal combination of viscosity and homogeneity of the system, is 7%. The obtained results confirm the need for further study of the mechanisms of interaction between rubber crumb and the bitumen matrix, as well as for optimizing the compositions and technological regimes for the preparation of modified binders, which will ensure more intensive use of rubber‑containing additives in road construction.