Durability assessment of hybrid FRP composite shell and its application to prestressed concrete girders

This paper presents the results of an experimental-analytical research program aimed at assessing the durability of a hybrid fiber-reinforced polymer (FRP) composite shell, incorporated as a protective barrier during construction to impede the ingress of deleterious elements into the lower flange of a prestressed concrete girder. A series of tests were performed on the FRP composite shell and FRP-concrete specimens to examine the effectiveness of the FRP shell as a barrier against ingress of aggressive elements, such as moisture and chlorides in controlled environments. In addition, scanning electron microscopy (SEM) was used to determine the effects of aging, temperature variation and chloride diffusion in the FRP-concrete specimens. These experimental results were used to model the ingress of chlorides and moisture into the FRP-concrete system to predict the service life of prestressed concrete bridge girders reinforced with FRP composite shells. The results showed that the FRP composite shell can provide significant resistance against chloride ingress by impeding the rate of its ingress and the total amount of chloride ions, thus considerably help in retarding the resulting deterioration reactions and significantly enhancing their service life.