Abstract The behavior of ordinary concrete and high strength concrete under a combinative effect of stress and chemical corrosion was studied in the present work. The concrete specimens were immersed in a variety of chemical solutions including 10%, 5%, 1% and 0.1% ammonium nitrate and simultaneously subjected to different flexural loads with load levels of 30%, 40% and 50% of their initial flexure strengths. The influences of the concentration of solutions, quality class of the concretes and load level of applied flexural stress on the strength of concretes were investigated. The relationships between life-time of the concrete and concentration of the solution, relative strength of the concrete and penetration depth of the ammonium nitrate solutions were determined. The mechanisms of stress corrosion of concrete exposed to ammonium nitrate solution and superimposed to a flexural stress was also discussed.