The scarcity of good aggregate in Japan led to an investigation of the use of a corrosion inhibitor for reinforced concrete. Corrosion current measured on small test specimens soaked in limewater for one day with an impressed voltage of + 400 mV with respect to the saturated calomel electrode shows that the introduction of calcium nitrite diminishes the corrosion of reinforcing steel in the presence of admixed sodium chloride. Long-term tests on larger specimens partially immersed in saturated sodium chloride solution indicate that admixed calcium nitrite can prevent the open circuit potential of reinforcing steel from entering the active region. Calcium nitrite was found to enhance the strength of concrete. Calcium nitrite complies with the requirements of ASTM Specification for Chemical Admixtures for Concrete (C 494-71). The use of a calcium-based admixture is expected to sidestep the issue of alkali-aggregate reactions and subsequent deterioration of concrete.