Operative consistence determination of the self-compacting concrete mix at plant or in construction conditions is important problem in building practice. Solving this problem the Abram’s cone, the Vebe’s device, the U-box siphon, L-box or funnel tests are used. However, these field methods are targeted on some indirect parameters determination of such very complicated paste-like material like concrete mix. They aren’t physical characteristics suitable for the rheological calculations of the coherence between the stress and strains, flow characteristics and the reaction of the concrete mix in different technological processes. In the Concrete mechanics laboratory of RTU were elaborated a conical plastometer having higher precision and less sensitive to the inaccuracy of the tests in construction condition. Also a new methodic were elaborated for the plasticity limit τ_0 calculation taking in the attention the buoyancy force of the liquid or non-liquid concrete mix. In the present investigation rheological test of the concrete mix by use the plastometer and mentioned earlier methodic was used for different self-compacting and not self-compacting concrete mixes.