“Durability Assessment-based Design" approach for structural applications of advanced cement-based materials

The prescriptive method, recommended by international codes for the durability design of concrete structures, provides limits on the mix composition and steel cover. The early loss of performance of several concrete structures clearly shows the inefficiency of this method especially for structures ex-posed to challenging service scenarios. For this reason, this approach must be replaced by a durability performance-based design approach that allows to define of the evolution of the structural performance over time and schedule, consequently, ordinary maintenance campaigns. This is especially true for ad-vanced cement-based materials, whose advantages, while automatically fulfilling the composition re-quirements above, can only be appreciated in an extended maintenance-free service life. To demonstrate the differences among the aforesaid approaches, a case study is herein presented dealing with a tank containing harsh water, rich in chlorides and sulphates, for which the degradation phenom-ena have been evaluated for both ordinary reinforced concrete and ultra-high durability concrete, both considered in the design. All results found for both materials have been evaluated and compared to show the difference in safety and reliability between these two methods.