This article presents the results related to the concentration of radionuclides and radioactivity index in the case of various mixing formulae of dry mortars.

The determinations have been carried out for 10 mixing formulae of plastering mortar (cement-lime and cement), where the Portland cement CEM I 42.5R, calcium hydrated lime EN 459/1 CL80-S and river aggregates originating from various areas of the Alba county are used.

The results reached indicate the influence of the origin of the river aggregates, differences between the concentrations of radionuclides being noticed in the case of mortars under test.