Durability assessment of hybrid FRP composite shell and its application to prestressed concrete girders M. Shafqat Ali a,⇑ , M. Saeed Mirza a , Larry Lessard b a Macdonald Engineering Building, Room 492, Department of Civil Engineering and Applied Mechanics, McGill University, 817 Sherbrooke Street West, Montreal H3A0C3, Canada b Macdonald Engineering Building, Room 362, Department of Mechanical Engineering, McGill University, 817 Sherbrooke Street West, Montreal H3A0C3, Canada highlights  Durability of a hybrid FRP composite shell is assessed.  Effectiveness of FRP shell as a protective barrier for concrete girder is examined.  FRP shell did not allow ingress of chlorides into the concrete.  Higher temperature (70 °C) caused degradation due to depolymerization of the matrix.  FRP shell on the lower girder ﬂange can be effective for enhancing their service life. article info Article history: Received 24 August 2016 Received in revised form 23 May 2017 Accepted 28 May 2017 Keywords: FRP composite shell Deterioration Durability Aggressive environment Chloride ingress FRP shell-concrete girder system Bridge girder Service life abstract 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 ser- vice life. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction In cold climate regions, prestressed concrete bridge girders can deteriorate principally from a variety of deterioration modes, including moisture variations in the concrete (wetting and drying cycles), freezing and thawing cycles, corrosion of the embedded reinforcing and prestressing steel, alkali-aggregate reactivity, sul- phate attack and other physical, mechanical, and chemical causes [1–4]. Based on the inspection results from several bridges operat- ing in aggressive environments, the concrete surface around the lower ﬂange of the girders was observed to suffer from the signif- icant deterioration, which ultimately led to corrosion of the prestressing steel [5]. This problem can be alleviated, or at worst slowed down considerably by incorporating a protective FRP com- posite shell around the lower girder ﬂange during construction [6– 8]. Over the past two decades, FRP composites have been used suc- cessfully used for the construction of new, and strengthening, rehabilitation and retroﬁtting of existing severely deteriorated infrastructure facilities [9–14]. Several applications of FRP compos- ite materials to new concrete construction, such as integrated FRP stay-in-place forms, act as external reinforcement. Concrete-ﬁlled FRP tubes have been used as piles in corrosive marine environ- ments and as bridge girders, piers, or columns [13,15–27]. These composite tubes ﬁlled with the concrete can be used for columns and composite bridge decks, beams and girders with varying geometry [10,17,19,20,22,26–30]. http://dx.doi.org/10.1016/j.conbuildmat.2017.05.214 0950-0618/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: muhammad.ali2@mail.mcgill.ca (M.S. Ali). Construction and Building Materials 150 (2017) 114–122 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat