Our goal was to verify the manufacturing availability of local Korean natural hydraulic lime (K-NHL) using local Korean low-grade limestone and to test the basic physical properties on the basis of EU standards (BS EN 459-1:2015). We also sought to improve the physical properties of natural hydraulic lime by adding inorganic by-products such as blast furnace slag and silica fume. Where the inorganic by-products were not incorporated, properties such as soundness, air content, particle size, and water absorption (excluding compressive strength and setting time) did not show significant differences with the physical properties evaluated based on EU standards. Also, in terms of the composition of hydraulic phase, local Korean NHL A5 and A8 were similar to NHL 2 of EU standards, whereas local Korean NHL HL correlated with NHL 3.5 or NHL 5. When inorganic by-products were added, the compressive strength and setting time were improved.