The Concentration of Radioactivities in Concrete Materials in Japan

To determine the concentration of radioactivity in materials constituting concrete in Japan, we carried out measurements of the components of concrete: steel, coarse aggregate, fine aggregate, cement, cement admixture, and water. Because the concentrations of radioactivity of steel, cement admixture, and water are far less than those of the other components, we measured only coarse aggregate, fine aggregate, and cement. The results of the measurements are found to lie in a wide range from 6.8-912.5 (average 516.9) Bq/kg for K-40, 2.93-86.7 (average 38.8) Bq/kg for U-238, and 1.59-61.6 (average 23.9) Bq/kg for Th-232. The results proved that the concentrations of radioactivity of components in concrete in Japan are lower than those in other countries. The radioactivity concentration in concrete according to geographic region showed nearly the same distribution pattern as the intensity of gamma rays from soil.