To enhance the sustainability of the construction sector, the use of alternative materials in concrete production is increasingly encouraged. One promising solution is the replacement of natural aggregates with artificial or recycled materials. Among these alternatives, Recycled Asphalt Pavement (RAP)—classified as construction and demolition waste—shows potential for concrete production due to its comparable properties to natural aggregates. To confirm the sustainability of RAP for the production of structural concrete, it is essential to assess the service life it can guarantee under various environmental exposure conditions, which is a key aspect of life cycle assessment. As part of the RAPCON project, funded by Fondazione Cariplo, the durability design of reinforced concrete (RC) elements made with RAP was evaluated using a probabilistic approach. The study focused on urban exposure conditions, specifically unsheltered environments (XC4 classification according to EN 206). This paper presents service life predictions for concrete incorporating two types of cement (CEM II/A-LL 42.5R and CEM IV/A(P-V) 42.5N-SR), two water/cement ratios (0.45 and 0.65), and varying RAP contents (20% to 100%). Reference concretes with only natural aggregates were also analyzed. The input parameters for the service life model were derived from experimental results and literature data. Findings indicate that, with a properly designed concrete mix, including an appropriate cement selection, a service life of approximately 50 years can be ensured—even with significant replacement of natural aggregates by RAP.