The aim of this research is to investigate how cement affects the properties of lime mortars. The usage of pure aerial lime binders reduces the water resistance and mechanic durability of the material. It determines that pozzolan additives or cement have to be used in lime mortar. Mixed cement lime mortar (with increasing amount of cement) were synthesized and their properties tested: density, chemical composition, water absorption rate, compressive strength, resistance to soluble salts and frost resistance. Portland cement can be used as a suitable additive to mortars, to improve their compatibility with the hydraulic and historic mortars.