[en] Tests were conducted on concretes from Hanford Waste Tank Farms, and on concrete cast by the Portland Cement Association using Hanford mix designs and materials. Elastic modulus (static method), Poisson's ratio, and compressive and splitting tensile strengths were determined at room temperature, and for specimens maintained at 250F for varying lengths of time. Variables examined were temperature, length of exposure to elevated temperature, and geometry of test specimens. Compressive strength generally decreased after specimens were exposed to heat. Maximum losses were 20 to 33 percent of room temperature strength. Initially stronger concretes lost a proportionately larger percentage of their strength after exposure than did weaker concrete. In some series, concrete appeared to gain strength after exposure. In other series, concrete initially lost strength, then recovered strength after prolonged heating. Splitting tensile strength of heated specimens followed trends similar to those obtained for compressive strength. Highest strength losses were about 40 percent. However, in most cases, considerably less strength deterioration resulted from exposure to heat. Modulus of elasticity and Poisson's ratio also decreasd after exposure to heat. Greatest losses were about 40 percent of room temperature values, but amounts differed widely among test series