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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. [ABSTRACT FROM AUTHOR]

This paper presents a practice-oriented method for design of flexural concrete members for a given service life in an aggressive environment. A time-dependent correlation between rebar corrosion level in terms of mass loss and its bond strength degradation at the steel–concrete interface, and the ultimate flexural and shear resistances of the reinforced concrete elements is evaluated using basic electrochemistry and empirical relationships. The design development length is determined based on the mass loss prediction and the equation depicting loss of bond strength with mass loss due to corrosion. The results show that the mass loss of rebars depends on several factors, such as the surface chloride concentration, cover thickness to rebar and concrete permeability, rebar size and ratio of the concrete cover thickness to the rebar diameter ( c/d b ratio). The model results predict the required development length at the end of the service life of 70 years to be more than twice that obtained from conventional reinforced concrete design. The proposed durability design procedure is illustrated with the help of a detailed design example. Analysis results show that because of corrosion the flexural and shear strengths decrease by about 80% and 52%, respectively, after the service life of 70 years. [ABSTRACT FROM AUTHOR]