Although the mechanical performance just after the production of short fiber reinforced concrete has been clarified, the evaluation of the mechanical performance after being exposed for a long time in view of the influence of water has not been made. Therefore, in this study, the bending strength and bending toughness of aramid short fiber reinforced concrete after exposure in water and air at different temperatures were evaluated. As a result, 1) The mechanical performance after exposure in water decreases with time as the exposure temperature is higher, while the mechanical performance after exposure in air is kept. 2) The mechanical performance after exposure for 100 years in water at 20°C was estimated by exposure for 1 month to 3 years in a high temperature water environment. 3) When bundled-type short fibers were mixed, it is expected to retain mechanical performance of 90% or more of the initial value even if exposed to water at 20°C for 100 years.
