The physical properties of natural hydraulic lime were improved through mixing biodegradable organic admixtures withnatural hydraulic lime manufactured by using low grade limestone produced in Korea in order to extend the scope ofapplication. The experiment was conducted according to the EU standards. A total of four organic admixtures (potato starch,corn starch, cellulose, and gelatin) were used to investigate the properties depending on the kind of organic admixture and thechanges in the properties depending on the amount of mixed organic admixtures. The results of the study showed that theinitial compressive strength on 7 days was increased and the setting time was shortened by the mixing of the organicadmixtures. Considering the physical properties such as compression strength, setting, air content, and soundness accordingto the EU standards, the best physical properties were obtained when corn starch, one of the four organic mixtures, was mixedat a mixing ratio of 1.0%.

Keywords: Natural hydraulic lime (NHL), Biodegradable organic admixture, Low-grade limestone, Physical property, Compressive strength