One of the primary concerns regarding the operation of reinforced concrete (RC) road bridge decks is the deterioration of concrete at the upper layer due to cyclic water pressure from vehicle loads, known as disintegration. This study aims to replicate disintegration deterioration via water-submerged fatigue tests using lab-scale RC specimens and to develop a method for quantitatively evaluating disintegration progression within the concrete. Reinforced concrete specimens of varying dimensions were fabricated, and three-point bending fatigue tests were conducted under dry and water-submerged conditions. The results revealed that concrete fracture at loading points occurred under water-submerged conditions, leading to shortened fatigue lives. Some specimens underwent a freezing-thawing cycle (FTC) process prior to fatigue testing to examine the combined effect, which was found to be insignificant due to limited FTC damage to matured concrete in this study. Surface hardness tests were performed during fatigue loading to assess surface deterioration, revealing a decreasing trend and increasing variances with an increase in the number of load cycles. This suggests the potential of hardness tests to evaluate disintegration progression.