Modeling of time depended changes of chloride diffusion coefficient

Today engineers have to consider durability of structures in the design process which is realized through the choice of materials and material's performance. Chloride diffusion coefficient is main parameter of durability properties of concrete, like compressive strength is of mechanical properties. In this paper chloride diffusion coefficient was determined for the structure of Krk bridge, which is located in aggressive marine environment, exposed to direct influence of chlorides for the period of more than 25 years. Chloride diffusion coefficient was calculated from chloride profiles measured on specimens taken from different testing places on bridge within inspection and maintenance works on the bridge. In this research results from 1989, 1994, 2000 and 2003 are taken into account and analysed. In order to evaluate change of chloride diffusion in time, results of on site testing were compared with chloride penetration testing in laboratory. Specimens for these testing were prepared from the same concrete mixture that was used during construction of this bridge. All results obtained during the research were compared with calculated chloride coefficient from existing durability models (DuraCrete, Life-365 and Chlodif) for given mixture and exposure time.